tag:blogger.com,1999:blog-77544759970618440692024-03-13T05:44:26.032-07:00Article'sUn-Published collection of article's virtually on all topics.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.comBlogger132125tag:blogger.com,1999:blog-7754475997061844069.post-29403959910592944302009-07-09T20:24:00.000-07:002009-07-09T20:31:06.680-07:00Dissecting a Computer Virus - Protecting Your Home Computer Plus Tips and ToolsProtecting Your Home Computer<br /><br />Your home computer is a popular target for intruders. Why? Because intruders (the bad guys) want what is stored there. They look for, passwords, credit card numbers, bank account information, social security numbers, identity information and anything else they can find. But it's not just money-related information they're after. Intruders also want your computer's resources, meaning your hard disk space, your fast processor, and your Internet connection. They use these resources to attack other computers on the Internet, or, they can disrupt your home computer's ability to perform as intended.<br /><br />Don't assume that your Internet Service Provider (ISP) will offer all the protections you need against home computer invasion. There are many security tools such as Antivirus and Antispyware, and Web filters that are completely free for home use.<br /><br />8 Tips to Protect Your Home Computer<br /><br />1. Patching – patch the operating system and applications monthly<br />a. Microsoft - Windows Update / Automatic Updates<br />b. Java, Adobe, iTunes – use a tool such as Secunia to scan monthly<br /><br />2. Antivirus – current version with daily/weekly updates, real-time scanning<br />3. Personal Firewall – Windows or third party such as Zone Alarm<br />4. Antispyware – scan weekly<br />5. Internet Safety<br />a. Web Filter– blocks spyware, virus infected and other unwanted sites that can damage your computer and steal your data or identity information. Blocks inappropriate sites.<br />b. MySpace/Facebook – (Social Networking) – Use caution and become educated. Children must be 14 years old to legally have their own MySpace/Facebook account. Parental permission required. Many viruses and worms come in through Social Networking “invites”. Be careful with URLs, attachments. Also see “Family Meeting” below.<br />c. Instant Messaging – AOL, Yahoo Messenger, MSN/Windows Live Messenger. Avoid attachments and URL links. “Check out this new screensaver” … or “Pic of Beyonce….” Don’t fall for it.<br />d. Skype – keep it patched.<br />e. Have a Family Meeting – Talk to kids/teens about Internet safety. Do not give out personal information of any kind without parental approval! (Address, birthday, phone number, school, age etc.) Predators are out there and pose as children/teens in chat rooms, game rooms, blogs etc. <br />f. Online Gaming -Xbox / Wii. They support web cams. Form of Social Networking. Who are they playing games with?<br />6. Email - Attachments: don’t click unless you are sure! Spam – Never click “unsubscribe” unless you know you actually preciously subscribed.<br />7. Mobile Devices – Smart phones/PDA/iPhone threats increasing slowly. 400 threats. <br />8. Wireless – secure the connection, WPA. Change default passwords.<br /><br />Tools & Tips<br /><br />The below information is presented as a courtesy to conference attendees. The presenters do not recommend, sanction, or promote specific computer security applications and/or tools. Most of the tools noted below are free for home and/or non-commercial use on personal devices.<br /><br />Home User Computer Security Tips<br />http://www.cert.org/tech_tips/home_networks.html<br /><br />Antivirus<br />Avast! (http://www.avast.com/eng/download-avast-home.html)<br />AVG (http://free.avg.com)<br />ClamWin (http://www.clamwin.com)<br /><br />Antispyware<br />Spybot Search & Destroy (http://www.safer-networking.org/en/index.html)<br />SuperAntispyware<br />Malwarebytes<br /><br />Internet Filtering<br />K-9 (Blue Coat, Free)<br />Bsafe (purchase)<br />Sandboxie (virtualized browser)<br /><br />Microsoft Patching<br />Windows Update – Automatic Updates<br /><br />Application Patching<br />Java, Adobe Reader, Adobe Flash, Quicktime, iTunes – update monthly<br />Secunia – very nice free web tool<br /><br />Malware Removal Tools<br />Malwarebytes<br />HijackThis<br />OTview<br />Process Explorer<br />Autoruns<br />WhatsRunning?<br />Msconfig<br />AV vendor specific removal tools: Symantec, McAfee, F-secure etc.<br /><br />Password Database<br />Encrypt passwords and important information. Use a password database tool.<br />KeePass Password Safe (http://keepass.info)<br />AnyPassword<br /><br />Browser Sandbox/Virtualization<br />Sandboxie (http://sandboxie.com)<br />VMWare Player<br />Microsoft VirtualPC<br /><br />Common Malware Load Points:<br /><br />Symantec tutorial: http://community.norton.com/norton/board/message?board.id=Announcements&thread.id=11<br /><br />C:\Documents and Settings\All Users\Start Menu\Programs\Startup<br />C:\Documents and Settings\[user name]\Start Menu\Programs\Startup<br />C:\Documents and Settings\Administrator\Start Menu\Programs\Startup<br />C:\Documents and Settings\Default User\Start Menu\Programs\Startup<br />C:\WinNT\Profiles\All Users\Start Menu\Programs\Startup<br />C:\WinNT\Profiles\[user name]\Start Menu\Programs\Startup<br />C:\WinNT\Profiles\Administrator\Start Menu\Programs\Startup<br />C:\WinNT\Profiles\Default User\Start Menu\Programs\Startup<br />C:\Windows\Start Menu\Programs\Startup<br />C:\Windows\All Users\Start Menu\Programs\Startup<br /><br />HKEY_CURRENT_USER\Software\Microsoft\Windows\currentversion\Run<br />HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\currentversion\runonce<br />HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\currentversion\runservices<br />HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\currentversion\runservicesonce<br />HKEY_CURRENT_USER\Software\Microsoft\Windows\currentversion\Policies\Explorer\Run<br />HKEY_CURRENT_USER\Software\Microsoft\windowsnt\currentversion\Windows<br />HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\currentversion\Run<br />HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\currentversion\runonce<br />HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\currentversion\runonceex<br />HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\currentversion\runservices<br />HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\currentversion\runservicesonce<br />HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\currentversion\Policies\Explorer\Run<br />HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\windowsnt\currentversion\Windows<br />HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\windowsnt\currentversion\Winlogon<br />HKEY_LOCAL_MACHINE\Software\Microsoft\windowsnt\currentversion\Windows\appinit_dlls<br />HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\currentversion\Explorer\sharedtaskscheduler<br />HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify<br />HKEY_LOCAL_MACHINE\Software\Microsoft\SharedTools\MSConfig\startupfolder<br />HKEY_LOCAL_MACHINE\Software\Microsoft\SharedTools\MSConfig\startupreg<br /><br />Task Scheduler<br />System.ini<br />Win.ini<br />BHO – Browser Helper Objects<br /><br />Infected file Submission<br />http://www.virustotal.com/<br />http://www.cwsandbox.org/<br />https://submit.symantec.com/websubmit/retail.cgi<br /><br /><br />Tools for dissecting a computer virus:<br />• Vtrap (Virus Trap) – Virus honey pot<br />• ClamWin – Antivirus<br />• Avast! – Antivirus<br />• AVG – Antivirus<br />• Sysinternal’s Process Explorer – Locating the virus, looking at the threads tree and reading strings in DLL (dynamic link library) files<br />• Anywhere PE Viewer – Viewing strings compiled into the virus and finding registry (Windows’ configuration database) keys<br />• Sysinternal’s Autoruns – Locating/disabling the virus at system auto load points<br />• Windows Scheduled Tasks, Services.msc, appwizard.cpl and msconfig.exe – Locating/disabling the virus<br />• Regedit – Exploring registry keys to identify virus activity<br />• IDA Pro Free Edition – Decompiling to assembly code, strings and function calls; running the virus in debug mode<br />• Boomerang – Decompiling to assembly code, exporting functions and decompiling to C code<br />• GNU C Compiler (gcc) – Compiling a custom version of the virus<br /><br /><br />Process for dissecting a computer virus:<br /> Look for signs of viral infection (sluggish, popup ads, home page or default search page changed, strange error messages)<br /> Update anti-virus signatures<br /> Run anti-virus and look at the report. If anything was found, was it deleted successfully?<br /> Look for unusual system activity and strange programs/tasks/services that are running<br />o Two factors can facilitate and speed up this process: experience (quickly recognizing what an unusual activity or program would look like), and a baseline of the system (knowing with certainty what the standard programs and services are, so that anything above the baseline can be considered unusual)<br /> Look at user and system auto load points for anything unusual<br />o User auto load points include Explorer/Internet Explorer browser helper objects, ActiveX controls, registry run and runonce keys, Start Up folder in the Start Menu, etc.<br />o System auto load points include scheduled tasks, registry run and runonce keys, services, drivers, environment variables, system startup files, etc.<br />o Again, both previous experience and baselines can increase the rate of success and speed of this process<br /> Once the virus is located, attempt to identify it through virus databases, virus reports, help forums and similar sites on the Internet<br /> Search the virus files for strings, import libraries (DLLs it uses) and registry keys to determine what it could possibly be doing to the system and where it could be doing it<br /> Decompile the virus to assembly code to identify:<br />o Function calls and the sequence in which they occur<br />o Possible information about the author (user ID, language spoken, programming language used, geographic location, computer configuration such as logical drives, OS, etc.)<br />o Intended users (based on the language and grammar in user messages, if any)<br />o Files touched, read, updated and/or created, as well as DLLs used for gaining the appropriate file permissions<br />o Registry keys used and information stored in the registry (load points, timestamps for last time the virus ran or the next time it should run, icons, URLs, IP addresses, etc.)<br />o Network DLLs, IP addresses, URLs used to upload or download data, port numbers (important for worms), and any functions to support incoming connections (which would be the case for a Trojan horse or botnet)<br />o User information accessed (cookies, profile paths, user ID, user name, password databases)<br />o Antivirus, firewall and anti-spyware signatures (common in resident viruses that avoid detection)<br />o Run mode (if a virus can run in MS-DOS mode, chances are it will load before the system boots, infect a Master Boot Record, or load as fake hardware driver)<br />o Images and icons (used by spyware, logic bombs and Trojan horses to disguise themselves as innocent files or valid system or antivirus software)<br />o Use this information to identify what the virus is doing, how to stop it and how to catch the bad guy who created it.<br /> Reverse engineer the virus to C, C++ or another high-level language if needed to customize it (be careful -- this may not be ethical nor legal!) or to create a removal tool. Compile back to object code with the compiler appropriate for that language (e.g., GCC)Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-25541046338307809552009-07-08T04:43:00.000-07:002009-07-08T04:44:51.680-07:00INFO : Taxation and New Budget (2009-2010)<div class=Section1> <p class=MsoNormal><o:p> </o:p></p> <div> <div> <p><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>The finance Minister, in his budget speech, announced marginal tax benefits for individual tax payers. He increased the basic exemption limit for male taxpayers and female taxpayers by Rs 10,000 and that of senior citizens by Rs 15,000. There is no change in the Corporate Tax rates while there has been a modest hike in the exemption limit on personal Income Tax. The exemption limit for Senior Citizens has been increased from Rs. 2.25 lakh to Rs. 2.40 lakh. For Women tax payers the exemption limit has been increased by Rs.10,000 to from Rs.1.80 lakh to Rs. 1.90 lakh and from Rs. 1.50 lakh to Rs.1.60 lakh for all other categories of individual taxpayers. He abolished the surcharge of 10% on income over Rs 10 lakh. <o:p></o:p></span></p> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p> </div> <div> <p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"; color:#00B050'>The new tax slabs now stand as follows:</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><br> <br> <b><span style='color:#C00000'>Male taxpayers</span></b><o:p></o:p></span></p> </div> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 style='border-collapse:collapse'> <tr> <td width=319 valign=top style='width:239.4pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Income Level<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Tax Rate<o:p></o:p></span></b></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Upto 1,60,000<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Nil<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1,60,001 to 3,00,000<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>10%<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>3,00,001 to 5,00,000<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>20%<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Above 5,00,000<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>30%<o:p></o:p></span></p> </td> </tr> </table> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p> </div> <div> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"; color:#C00000'>Female taxpayers<o:p></o:p></span></b></p> </div> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 style='border-collapse:collapse'> <tr> <td width=319 valign=top style='width:239.4pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Income Level<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Tax Rate<o:p></o:p></span></b></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Upto 1,90,000 <o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Nil<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1,90,001 to 3,00,000<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>10%<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>3,00,001 to 5,00,000<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>20%<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Above 5,00,000<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>30%<o:p></o:p></span></p> </td> </tr> </table> <div> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"; color:#1F497D'><br> </span></b><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"; color:#C00000'> Senior citizens<o:p></o:p></span></b></p> </div> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 style='border-collapse:collapse'> <tr> <td width=319 valign=top style='width:239.4pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Income Level<o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Tax Rate<o:p></o:p></span></b></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Upto 240000 <o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Nil<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>240000 to 300000 <o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>10%<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>300001 to 500000 <o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>20%<o:p></o:p></span></p> </td> </tr> <tr> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Above 500000 <o:p></o:p></span></b></p> </td> <td width=319 valign=top style='width:239.4pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>30%<o:p></o:p></span></p> </td> </tr> </table> <div> <div style='border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 1.0pt 0in'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>In addition to this, an education cess of 3% on the tax amount continues. But a 10% surcharge on income over Rs 10 lakh has been abolished.<o:p></o:p></span></p> </div> </div> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p> </div> <div> <p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"; color:#00B050'>Saving from revised Tax rates<o:p></o:p></span></b></p> </div> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>With the help of below given Table you can understand, what will be your saving from the revision <o:p></o:p></span></p> </div> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p> </div> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> For men and women <o:p></o:p></span></p> </div> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 style='border-collapse:collapse'> <tr> <td width=91 valign=top style='width:.95in;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Taxable income (Rs)<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Tax - before budget<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Tax -after budget<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Difference<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></b></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Male<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Female<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Male<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Female<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Male<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Female<o:p></o:p></span></b></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>2,00,000<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>5150<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>2060<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>4120<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1029<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1030<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1031<o:p></o:p></span></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>5,00,000<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>56650<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>53560<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>55620<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>52529<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1030<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1031<o:p></o:p></span></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>10,00,000<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>211150<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>208060<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>210120<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>207029<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1030<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1031<o:p></o:p></span></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>12,00,000<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>300245<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>296845<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>271919<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>268829<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>28326<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>28016<o:p></o:p></span></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>15,00,000<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>402215<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>398815<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>364619<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>361529<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>37596<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>37286<o:p></o:p></span></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>20,00,000<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>572165<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>568765<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>519119<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>516029<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>53046<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>52736<o:p></o:p></span></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>25,00,000<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>742115<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>738715<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>673619<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>670529<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>68496<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F8EDED;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>68186<o:p></o:p></span></p> </td> </tr> <tr> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>40,00,000<o:p></o:p></span></b></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1251965<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1248565<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1137119<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1134029<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>114846<o:p></o:p></span></p> </td> <td width=91 valign=top style='width:.95in;background:#F2DBDB;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>114536<o:p></o:p></span></p> </td> </tr> </table> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>For senior citizens<o:p></o:p></span></p> </div> <table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 style='border-collapse:collapse'> <tr> <td width=160 valign=top style='width:119.7pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Taxable income (Rs)<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Tax before budget<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Tax after budget<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;border:none;border-bottom:solid white 1.5pt; background:#9E3A38;padding:0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Difference<o:p></o:p></span></b></p> </td> </tr> <tr> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>2,00,000<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Nil<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Nil<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Nil<o:p></o:p></span></p> </td> </tr> <tr> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>5,00,000<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>49875<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>47379<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>2496<o:p></o:p></span></p> </td> </tr> <tr> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>10,00,000<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>203424<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>201879<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1545<o:p></o:p></span></p> </td> </tr> <tr> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>12,00,000<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>291746<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>263679<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>28067<o:p></o:p></span></p> </td> </tr> <tr> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>15,00,000<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>393716<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>356379<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>37337<o:p></o:p></span></p> </td> </tr> <tr> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>20,00,000<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>563667<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>510879<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>52788<o:p></o:p></span></p> </td> </tr> <tr> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>25,00,000<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>733617<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>665379<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F2DBDB;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>68238<o:p></o:p></span></p> </td> </tr> <tr> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>40,00,000<o:p></o:p></span></b></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1243467<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>1128879<o:p></o:p></span></p> </td> <td width=160 valign=top style='width:119.7pt;background:#F8EDED;padding: 0in 5.4pt 0in 5.4pt'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>114588<o:p></o:p></span></p> </td> </tr> </table> <div> <div style='border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 1.0pt 0in'> <p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"; color:#1F497D'><o:p> </o:p></span></b></p> </div> <p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"; color:#1F497D'><br> </span></b><b><span style='font-family:"Calibri","sans-serif";color:#00B050'>Below given are the changes announced in Budget 2009 - 2010 that will have some impact on your personal taxation. <o:p></o:p></span></b></p> </div> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p> </div> <div> <p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><b><span style='font-size:11.0pt;font-family: "Calibri","sans-serif"'>Marginal Increase in Tax Exemption</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>: Personal income tax exemption limit raised for senior citizens by Rs 15,000 and for all others by Rs 10,000.<o:p></o:p></span></p> <p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><b><span style='font-size:11.0pt;font-family: "Calibri","sans-serif"'>Higher Deduction under Section 80DD</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>: Annual deduction relating to maintenance, including medical treatment, for a dependent with severe disability (more than 80%) has been raised to Rs 1 lakh from the current Rs 75,000.<o:p></o:p></span></p> <p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><span style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><b><span style='font-size:11.0pt;font-family: "Calibri","sans-serif"'>Expanded Scope of Section 80E</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>: Annual deduction in respect of interest on loans taken for higher education purposes has been expanded from the current limited list of courses to cover all fields of studies, including vocational studies, pursued after completion of schooling.<o:p></o:p></span></p> <p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><span style='mso-list:Ignore'>4.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><b><span style='font-size:11.0pt;font-family: "Calibri","sans-serif"'>Elimination of Surcharge</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>: The 10% surcharge on taxes for those earning annual income above Rs 10 lakhs will no longer exist. This will lead to a tax saving for higher income earners<o:p></o:p></span></p> <p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><span style='mso-list:Ignore'>5.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><b><span style='font-size:11.0pt;font-family: "Calibri","sans-serif"'>Abolishment of Fringe Benefit Tax (FBT)</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>: FBT on the value of fringe benefits provided by employers to employees has been abolished. Reimbursements will be taxed as perquisites at the marginal tax rate. This might increase the tax burden on employees.<o:p></o:p></span></p> <p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><span style='mso-list:Ignore'>6.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><b><span style='font-size:11.0pt;font-family: "Calibri","sans-serif"'>Increase in Wealth Tax Exemption</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>: The exemption limit for wealth tax has been increased from Rs 15 lakhs to Rs 30 lakhs.<o:p></o:p></span></p> <p class=MsoListParagraph style='text-indent:-.25in;mso-list:l2 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><span style='mso-list:Ignore'>7.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><b><span style='font-size:11.0pt;font-family: "Calibri","sans-serif"'>Automation of Tax Filing Procedure</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>: Reiteration of the re-engineering of the key business processes around the filing of direct taxes. Expect simplified tax filing in the near future, with the prospect of quicker refunds.<o:p></o:p></span></p> <div style='border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 1.0pt 0in'> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <span style='color:#1F497D'><o:p></o:p></span></span></p> </div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"; color:#1F497D'><o:p> </o:p></span></p> </div> <div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Corporate Tax rates<o:p></o:p></span></p> </div> <ul style='margin-top:0in' type=disc> <li class=MsoNormal style='mso-list:l1 level1 lfo5'><span style='font-size: 11.0pt;font-family:"Calibri","sans-serif"'>Corporate Tax rates - No Changes in corporate Tax, it continues to stand at 30% plus surcharge of 10% of the corporate tax (for companies with profits above Rs 10 million) along with an education cess that amounts to 3% of corporate tax, totalling to 33.9%.<o:p></o:p></span></li> <li class=MsoNormal style='mso-list:l1 level1 lfo5'><span style='font-size: 11.0pt;font-family:"Calibri","sans-serif"'>Fringe Benefit Tax (FBT) - Fringe Benefit Tax is abolished<o:p></o:p></span></li> <li class=MsoNormal style='mso-list:l1 level1 lfo5'><span style='font-size: 11.0pt;font-family:"Calibri","sans-serif"'>Minimum Alternate Tax (MAT) - Increased to 15% of book profit <o:p></o:p></span></li> <li class=MsoNormal style='mso-list:l1 level1 lfo5'><span style='font-size: 11.0pt;font-family:"Calibri","sans-serif"'>Commodity transaction tax (CTT) – CTT is cancelled<o:p></o:p></span></li> <li class=MsoNormal style='mso-list:l1 level1 lfo5'><span style='font-size: 11.0pt;font-family:"Calibri","sans-serif"'>Goods and Services Tax (GST) – GST is to be implemented by April 2010, cumulative incidence of GST expected to be around 18%<o:p></o:p></span></li> </ul> <p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt; font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p> </div> </div> <p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p> </div> Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-73870037020541237492008-12-21T20:20:00.001-08:002008-12-23T01:17:25.193-08:00A useful bit of info .. PNR status in mobile ... no premium charges (SAVE THIS NO.)<div class=Section1> <div> <p class=MsoNormal><span lang=EN-GB style='font-size:13.5pt;font-family:"Bookman Old Style","serif"; color:#824200'>Indian Railway in collaboration with Google is now providing a 10 digit <br> Mobile number. Just SMS your PNR number on this mobile number and <br> instantaneously you will get your ticket's current status along with all <br> other journey related details. <br> <br> The number is <b>9773300000 </b>. NO need to prefix 0 or +91. <br> <br> </span><span lang=EN-GB style='font-size:13.5pt;font-family:"Bookman Old Style","serif"; color:blue'><br> Best of all, you don't pay a premium charge for any of this, <br> just the price of a standard SMS </span><span lang=EN-GB style='font-size:13.5pt; font-family:"Bookman Old Style","serif";color:#824200'>. <br> <br> For more details: <b><a href="http://www.google.co.in/mobile/default/sms/" target="_blank">http://www.google.co.in/mobile/default/sms/# </a></b><br> <br> DON FORGET TO STORE THE NBR IN MOBILE. </span><span style='font-size:11.0pt; font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p> </div> </div> Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-86452707187973892942008-12-14T23:44:00.001-08:002008-12-23T01:17:25.194-08:00FTP File Compression<center><br /><br /></center> Own a personal computer for any amount of time, and you will quickly realize that the amount of storage space on your computer is limited. One way to deal with this problem is to use a compression software package that "squishes" unused programs into small "boxes", thus freeing up a little more of your disk space for other programs. <p> It turns out that storage space problems are not limited solely to personal computers. As the numbers of files that are available through ftp increases daily, ftp sites are actively looking for ways to squeeze more files into a limited amount of space. </p><p> The ftp sites accomplish this by using file compression. </p><p> The good news is that a compressed file takes up a lot less space on the ftp site's computer. The bad news is that a compressed file is absolutely useless until you uncompress it. </p><p> Wait ... it gets worse. Before you can uncompress a file, you have to know what compression method was used to compress the file in the first place. Unfortunately, there is no one standard ftp file compression method -- there are HUNDREDS of different file compression methods in use today :( </p><p> If you have to know what compression method was used before you can uncompress a file, how are you ever going to figure out which method was used? Well, it is actually pretty easy: </p><ol><li>Most ftp directories have a <tt>READ.ME</tt> file that shows an index of all the files that are in that directory. Some really nice ftp sites have expanded <tt>READ.ME</tt> files that include a mention about what compression method was used and where you can get a free copy of the software needed to uncompress the files.<br /><br /></li><li>Look at the files' extensions. By looking at the extensions and comparing them to the chart below, you will be able to determine what compression method was used and what particular software is needed to uncompress the file. </li></ol> Fortunately, most uncompression software is either public domain (meaning that it is completely free) or shareware (meaning that you can get a copy of it for free, but the author expects you to send him some money for the program if you decide to keep it and use it). Best of all, most uncompression software is available through ftp! :) <p> The list below shows some of the most popular extensions that you are bound to encounter during your visits to ftp sites around the world. It also shows transfer modes needed to retrieve files with these extensions, what uncompress software package you need to to uncompress the files after you retrieve them, and it even gives some additional comments about each of the extensions. </p><p> Paraphrasing something I said in <a href="http://www.ewp.rpi.edu/hartford/tis//Roadmap/MAP01.html">MAP01: Welcome</a>, I want you to be aware that the one compression method that isn't listed below is going to be the one compression package that you ADORE. Please do not take this personally. There are literally HUNDREDS of compression methods in use today, and there is no way that I can list all of them. </p><p> <b>Suggestion:</b> Save the following list, and use it as a reference tool for when you encounter an extension that you have never seen before :) Also, please notice that the following list talks about "archie". Archie is an FTP search tool that we will discuss in the next lesson. </p><hr /> (the following list was adapted from "The EFF's Guide to the Internet" by Patrick Crispen) <pre>FILE TRANSFER UNCOMPRESS<br />EXTENSION MODE PACKAGE ADDITIONAL COMMENTS<br />------------ ------ ---------- -----------------------------------<br /><br />.txt or .TXT ASCII By itself, this means the file is<br /> a document rather than a program,<br /> and does not need to be uncompressed<br /><br />.ps or .PS ASCII A PostScript document (in Adobe's<br /> page description language). You can<br /> print this file on any PostScript<br /> capable printer or use a previewer,<br /> like GNU project's GhostScript.<br /><br />.doc or .DOC ASCII Another common extension for text<br /> documents. (Be careful, though: .doc<br /> and .DOC extensions are also used for<br /> Microsoft Word documents (which are<br /> Binary files). The duck theory will<br /> help you determine the difference)<br /> No decompression is needed, unless it<br /> is followed by:<br /><br />.Z Binary uncompress This indicates a Unix compression<br /> method. To uncompress type<br /><br /> uncompress filename.Z<br /><br /> and hit enter at your host system's<br /> command line.<br /><br /> u16.zip is an MS-DOS program that<br /> will let you download .Z files and<br /> uncompress them on your own computer.<br /> The Macintosh equivalent program is<br /> called MacCompress (use archie to<br /> find these).<br /><br />.zip or .ZIP Binary PKZip or This indicates the file has been<br /> Zip/Unzip compressed with a common MS-DOS<br /> compression program, known as PKZIP<br /> (use archie to find PKZIP204.EXE).<br /> Many Unix systems will let you un-ZIP<br /> a file with a program called unzip.<br /><br />.gz Binary gunzip A Unix version of ZIP. To uncompress,<br /> type<br /><br /> gunzip filename.gz<br /><br /> at your host system's command line.<br /><br />.zoo or .ZOO Binary zoo A Unix and MS-DOS compression<br /> format. Use a program called zoo<br /> to uncompress.<br /><br />.shar or .Shar Binary unshar Another Unix format. Use unshar<br /> to uncompress.<br /><br />.tar Binary tar Another Unix format, often used<br /> to compress several related files<br /> into one large file. All Unix<br /> systems will have a program called<br /> tar for "un-tarring" such files.<br /> Often, a "tarred" file will also be<br /> be compressed with the gz method,<br /> so you first have to use uncompress<br /> and then tar.<br /><br />.sit or .Sit Binary StuffIt A Macintosh format that requires<br /> the StuffIt program.<br /><br />.ARC Binary ARC or Another MS-DOS format, which<br /> ARCE requires the use of the ARC<br /> or ARCE programs.<br /><br />.LHZ Binary LHARC Another MS-DOS format; requires<br /> the use of LHARC.<br /></pre> <a name="FewWords"> "A few last words of caution: </a> check the size of a file before you get it. The Net moves data at phenomenal rates of speed. But that 500,000-byte file that gets transferred to your host system in a few seconds could take more than an hour or two to download to your computer if you're using a 2400-baud modem. Your host system may also have limits on the amount of bytes you can store online at any one time. Also, although it is really extremely unlikely you will ever get a file infected with a virus, if you plan to do much downloading over the Net, you'd be wise to invest in a good anti-viral program, just in case." <a href="http://www.ewp.rpi.edu/hartford/tis//Roadmap/MAP16.html#Sources">(1)</a> <p> </p><h3>FTPMAIL AND BINARY FILES</h3> Yesterday, I showed you that it is possible to get ftp files using e-mail by sending an e-mail letter to one of the following addresses <pre> Australia ftpmail@cs.uow.edu.au<br /> France ftpmail@grasp.insa-lyon.fr<br /> Germany ftpmail@ftp.uni-stuttgart.de<br /> Great Britain ftpmail@doc.ic.ac.uk<br /> Ireland ftpmail@ieunet.ie<br /> Sweden ftpmail@lth.se<br /> USA ftpmail@sunsite.unc.edu<br /> USA ftpmail@ftp.uu.net<br /> USA ftpmail@decwrl.dec.com<br /></pre> with the following commands in the body of your e-mail letter <pre> reply <your><br /> connect <ftp><br /> <transfer><br /> chdir <directory><br /> get <filename><br /> quit<br /></pre> Before I introduce you to the new stuff, there are a couple of things that I want to review with you. <p> First, the </p><ul><tt>reply <your></tt></ul> command tells the FTPmail address where you want the file sent. If you use the example that I gave you yesterday <pre> reply pcrispe1@ua1vm.ua.edu<br /> connect ftp.sura.net<br /> ascii<br /> chdir /pub/articles<br /> get fall91.issue<br /> quit<br /></pre> without changing the reply address, FTPmail is going to send the file to <b>me</b>, not to you :) <p> Please remember to change the reply line to include <b>your</b> Internet e-mail address. </p><p> Also, I did not mention this in the last lesson, but FTPmail limits you to only one CHDIR command per letter. </p><p> Finally, in the last lesson I asked you to contact you local Internet service provider to see if they placed any size limits on file transfers. If they do, there is an additional command that you need to add to your list of commands </p><ul><tt>chunksize <size></tt></ul> This command will break the files into chunks that your system can handle. If your system has a 50,000 character limit on messages from the Internet, your chunksize command should be <ul><tt>chunksize 49000</tt></ul> (you want to make sure that you set your chunksize below what your system's limits are). This command will break your file into 49,000 character chunks, and will then send the chunks to you :) <p> You already now how to retrieve ASCII text files using FTPmail. In this lesson I am going to show you how to retrieve Binary files using FTPmail. </p><p> Binary file transfers using FTPmail aren't difficult ... they just require a few additional steps. Because all e-mail has to be in ASCII form, FTPmail has to encode your Binary file in ASCII before it can e-mail the file to you. Once you get the file, you can then decode the file back into Binary :) </p><p> Fortunately, there are two ways that FTPmail can encode Binary files into ASCII. The first way it can do this is through something called "uuencode." As long as you have a uudecode program -- and uudecode programs are all over the place (chances are your site has uudecode stored on its system) -- the whole process is simple. </p><p> The second encoding type that you can use is called "btoa" (binary to ascii). Your local Internet service provider will be able to tell you a little more about btoa. </p><p> So, to get ASCII files using FTPmail, you would use the following commands in the body of your letter to the FTPmail address: </p><pre> reply <your><br /> connect <ftp><br /> ascii<br /> chdir <directory><br /> chunksize <size><br /> get <filename><br /></pre> and to get Binary files using FTPmail, you would use the following commands in the body of your letter to the FTPmail address: <pre> reply <your><br /> connect <ftp><br /> <uuencode><br /> chdir <directory><br /> <encoding><br /> chunksize <size><br /> get <filename><br /></pre>Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-58547079671038374382008-12-11T03:09:00.000-08:002008-12-23T01:17:25.194-08:00Google - Tips 'n' tricks, submission, listing and ranking<h1><br /> <!-- #EndEditable --></h1><!-- #BeginEditable "content" --> <p><img src="http://www.entheosweb.com/images/search_engines/google_big.gif" alt="Google" align="right" width="139" height="46" />Google seems to be rapidly becoming the most popular search engine. Submitting, getting listed and getting a high ranking in Google can get you a lot of traffic, usually even more than Yahoo. Google uses link popularity while ranking web sites which results in quality search results therefore making it a favorite among most web searchers.</p> <ul class="bullet2"><li> <p> </p> <span class="subtitle">Submitting to Google</span><br /> You need to only submit your homepage o Google. It will automatically index the entire site. <b>Don't</b> submit individual pages of your site.<br /> <span class="subtitledk"><img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> Tip: </span>Google's crawler Googlebot will follow all the links in your site. So make sure all your pages are linked otherwise some of your pages will not get indexed.<br /> <img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.google.com/addurl.html">Submit to Google here</a><br /> <br /> </li><li><span class="subtitle">Getting Listed in Google<br /> </span>Getting listed in Google is usually very fast. We got listed within 2 weeks and all our new pages are usually listed within a month. The time frame depends on their crawl schedule and how many other web sites are in queue to be indexed before ours. In our experience, Google usually lists a site within a month.<br /> <br /> <span class="subtitledk"><img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> Tip:</span> Make sure your web site is ready before you submit it to be listed. Google will index your entire site, <span class="subtitlered">content</span><b> </b>and all. It takes keywords from the metatags as well as the content. You'll find that Google will send you the maximum amount of traffic (in our case it is triple of what Yahoo send us - and Yahoo is supposed to be the #1 Search Engine), so time well spent on your web site will pay off in the long run.<br /> <br /> <img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <span class="subtitledk">Tip:</span> Google usually indexes sites during the 2nd week and lists new content during the first few days of the next month. We usually see our new content added on the 2nd or 3rd of the month. A safe bet is to wait for a month to see new pages listed.<br /> <br /> </li><li> <span class="subtitle">Ranking in Google</span><br /> Getting listed in Google is pretty easy but what really matters is your ranking. The best way to get a high ranking in Google is to have many sites linking to your site. As Google uses link popularity as its most important factor in ranking web sites, getting many sites to link to you is your best bet in getting a high ranking. Get quality links and increased visitor traffic with only minutes of submission efforts!<br /> <br /> <span class="subtitledk"><img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> Tip:</span> Try to develop quality content which is different from what other sites are offering and you're guaranteed to get a high ranking in Google. Think of specialized <a href="http://www.entheosweb.com/website_promotion/metatags.asp#keywords">keywords</a> instead of using generic terms. Using generic keywords would usually land you in the 30th or 40th page whereas using specialized, or a combination of keywords would get you in the 1st or 2nd page of search results. Think of writing articles that others have not written and you're sure to come up in the first 10 search results. E.g If we were to write an article on web design we would probably come up in the 100th page of search results, whereas if we were to write on 'Creating Swap Images in Fireworks' we would probably come up in the first 10 search results. </li></ul> <p> <span class="subtitle">Google Tips 'n Tricks</span><br /> </p><ol class="bullet"><li>Make sure all your important keywords should appear in your title, description, content and alt tags of your web page. This increases your keyword density and helps in boosting your ranking. <br /> <br /> </li><li>Write articles, give away freebies and make your site a quality site with fresh content. Sites will automatically link to you thus increasing your link popularity.<br /> <br /> </li><li>Here's a cool trick to find out if you are <span class="subtitle">listed in Google</span>. Type this URL in your browser<br /> <span class="subtitlered">http://www.google.com/search?</span><b><br /> </b><span class="subtitlered">q=YOURDOMAIN+site:WWW.YOURDOMAIN.COM</span><b> </b><br /> Google will return to you a complete list of all pages that lie on yourdomain.com that exist within the Google catalog.<br /> Example<br /> http://www.google.com/search?q=entheosweb+site:www.entheosweb.com<br /> <br /> </li><li>You can also find out how many sites that are listed in Google are linking to your site. Here's the trick. Type this URL in the browser and watch the results.<br /> <span class="subtitlered">http://www.google.com/search?as_lq=YOURDOMAIN.COM</span><b> </b><br /> Google will return to you the number of pages which link to your web site in addition to a listing of each URL.<br /> Example:<br /> http://www.google.com/search?as_lq=entheosweb.com</li></ol>Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-45688006728922969572008-12-11T03:08:00.002-08:002008-12-23T01:17:25.194-08:0010 Tips To Effective Search Engine Submission And Promotion<h1><br /> <!-- #EndEditable --></h1><!-- #BeginEditable "content" --> <ol class="bullet2"><li> <p> </p><table align="right" border="0" cellpadding="0" cellspacing="1"> <tbody><tr> <td><script type="text/javascript"><!-- google_ad_client = "pub-1148387067248465"; /* 300x250, created 11/19/08 */ google_ad_slot = "5692836953"; google_ad_width = 300; google_ad_height = 250; //--> </script> <script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script><script>window.google_render_ad();</script><iframe name="google_ads_frame" src="http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-1148387067248465&dt=1228993721852&lmt=1228993721&prev_slotnames=0607187128&output=html&slotname=5692836953&correlator=1228993721755&url=http%3A%2F%2Fwww.entheosweb.com%2Fwebsite_promotion%2Ften_tips_effective_submission.asp&ea=0&ref=http%3A%2F%2Fwww.entheosweb.com%2Fwebsite_promotion%2Fdefault.asp&frm=0&ga_vid=1639725682.1228993374&ga_sid=1228993374&ga_hid=1948793409&ga_fc=true&flash=10.0.12&u_h=1024&u_w=1280&u_ah=994&u_aw=1280&u_cd=32&u_tz=330&u_his=2&u_java=true&u_nplug=14&u_nmime=61&dtd=3" marginwidth="0" marginheight="0" vspace="0" hspace="0" allowtransparency="true" scrolling="no" width="300" frameborder="0" height="250"></iframe></td> </tr> </tbody></table> <span class="subtitle">Meta tags</span><br /> The first and most important step is to <a href="http://www.entheosweb.com/website_promotion/metatags.asp">create relevant meta tags</a> after studying your competition and coming up with the most important keywords for you site. All the pages in your web site must have the relevant keywords, title and description.<br /> <br /> </li><li><span class="subtitle">Keywords in your Content</span><br /> The <a href="http://www.entheosweb.com/website_promotion/metatags.asp#keywords">keywords</a> used in your meta tags should be repeated in your content - specially in the heading and the first paragraph.<br /> <br /> </li><li class="text"><span class="subtitle">Alt Tags</span><br /> Put your keywords in the image alt tags. Some search engines index the alt tags.<br /> The <b>golden rule</b> for effective search engine submission is that all your important keywords should appear in your title, description, content and alt tags of your web page. This increases your keyword density and helps in boosting your ranking with the search engines.<br /> <br /> </li><li><span class="subtitle">Create Doorway Pages</span><br /> Create doorway pages for your most important keywords. These keyword specific pages will rank higher in the search engines and can be used as a doorway to your site.<br /> <br /> </li><li><span class="subtitle">Site Readiness</span><br /> Directory submissions are reviewed by people, so make sure your site is 100% complete before submitting it.<br /> <br /> </li><li><span class="subtitle">No special Symbols in your URL</span><br /> Don't put any special symbols in your URL (e.g. &, %,=, $ ,? ). Search engines cannot recognize these symbols.<br /> <br /> </li><li><span class="subtitle">Don't Spam</span><br /> Try to stay in the search engines' good books by not spamming. Spamming includes excessive keyword repetition, machine generated doorway pages with little or no content and pages that contain invisible text.<br /> <br /> </li><li><span class="subtitle">Submit to the Major Search Engines and Directories</span><br /> Make sure you have submitted your web site to the 10 big <a href="http://www.entheosweb.com/website_promotion/search_engine_submission.asp">search engines</a> and <a href="http://www.entheosweb.com/website_promotion/directory_submission.asp">directories</a>. Most of your traffic will be generated from these search engines. Keep checking to see if your web site is indexed. Dmoz, Direct Hit and Inktomi seem to be gaining a lot of importance so make sure that you are listed in these sites. Their results are used by a number of other important search engines.<br /> <br /> </li><li><span class="subtitle">Don't change the URL of your pages after submission</span><br /> Never change the path of any of your web pages after submitting your web site. Don't rename a file or change the file extension. This can really hurt your promotion efforts because it will show up as a dead link in the search results page.<br /> <br /> </li><li><span class="subtitle">Be Patient</span><br /> Don't expect miracles overnight. It may take anywhere from 2 weeks to 5 months to be indexed in the big search engines and directories. Keep checking every week and be patient. Continue to add quality content to your site. That will be a sure winner.</li></ol>Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-90996042336054306622008-12-11T03:08:00.001-08:002008-12-23T01:17:25.194-08:00Search Engine Submission Tips<h1><br /><!-- #EndEditable --></h1><!-- #BeginEditable "content" --> <p> </p><table align="right" border="0" cellpadding="0" cellspacing="1"> <tbody><tr> <td><script type="text/javascript"><!-- google_ad_client = "pub-1148387067248465"; /* 300x250, created 11/19/08 */ google_ad_slot = "5692836953"; google_ad_width = 300; google_ad_height = 250; //--> </script> <script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script><script>window.google_render_ad();</script><iframe name="google_ads_frame" src="http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-1148387067248465&dt=1228993673998&lmt=1228993672&prev_slotnames=0607187128&output=html&slotname=5692836953&correlator=1228993673929&url=http%3A%2F%2Fwww.entheosweb.com%2Fwebsite_promotion%2Fsearch_engine_submission.asp&ea=0&ref=http%3A%2F%2Fwww.entheosweb.com%2Fwebsite_promotion%2Fdefault.asp&frm=0&ga_vid=1639725682.1228993374&ga_sid=1228993374&ga_hid=1649568987&ga_fc=true&flash=10.0.12&u_h=1024&u_w=1280&u_ah=994&u_aw=1280&u_cd=32&u_tz=330&u_his=2&u_java=true&u_nplug=14&u_nmime=61&dtd=2" marginwidth="0" marginheight="0" vspace="0" hspace="0" allowtransparency="true" scrolling="no" width="300" frameborder="0" height="250"></iframe></td> </tr> </tbody></table> Search Engine submission is an important factor that could help make your business succeed online. In order to get the best results from search engines, Entheos offers you the following web site submission tips. <p>Before you start the process of submitting your web site to all the major search engines, make sure that you have optimized your web pages and checked your site thoroughly. If you would like to learn more about this, read our article on <a href="http://www.entheosweb.com/website_promotion/metatags.asp">Preparing your web pages for effective web site promotion leading to high search engine ranking</a></p> <p> <span class="subtitle">It's easy! Just read our tips, click on our links and submit your site</span></p> <p>In this section we have made a list of all the major search engines which will drive approximately 80% of visitor traffic to your site. These are the search engines that you need to focus on getting listed in. We have given tips on submitting to these search engines and have provided links to their 'Add URL' pages. All you have to do is read our tips, click on our links and submit your site to the top search engines. It's that simple. You'll be finished in just an hour or two.</p> <p>Are you ready? Have fun. Work hard. Get ready for a lot of traffic! </p> <p><a name="search_engines"></a><img src="http://www.entheosweb.com/images/search_engines/altavista.gif" alt="Altavista Search Engine" width="89" height="29" /><br /> AltaVista usually adds a page within a few days. It's best to submit only a few URLs per day to them, even though they appear to accept as many as you try to feed them. For whatever reason, they just don't seem to index them as quickly if you give them a lot at once. All you need to do is submit your URL.</p> <p><img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://addurl.altavista.com/addurl/new" target="_blank">Submit to Altavista here</a></p> <p><img src="http://www.entheosweb.com/images/search_engines/google.gif" alt="Google Search Engine" width="74" height="28" /><br /> Google is one of our personal favorites. It makes heavy use of link popularity as a primary way to rank web sites. This can be especially helpful in finding good sites in response to general searches such as "cars" and "travel," because users across the web have in essence voted for good sites by linking to them. The system works so well that Google has gained widespread praise for its high relevancy. Google also provides some results to Yahoo and Netscape Search. Submit only your homepage URL. It will automatically index the entire site.</p> <p><img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.google.com/addurl.html" target="_blank">Submit to Google here</a></p> <p><img src="http://www.entheosweb.com/images/search_engines/excite.gif" alt="Excite Search Engine" width="54" height="21" /><br /> Excite claims it takes about two weeks to add a submitted URL to its index. Sometimes, but not always. You'll need to be very persistent with them. But take the time to do it, Excite is the primary search service for the new giant AOL/Netscape. </p> <p><img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.excite.com/info/add_url_form" target="_blank">Submit to Excite here</a></p> <p><img src="http://www.entheosweb.com/images/search_engines/lycos.jpg" alt="Lycos Search Engine" width="90" height="28" /><br /> Its main listings come from the Open Directory project, and then secondary results come from either Direct Hit or Lycos' own spider. Just follow their simple instructions and don't expect immediate results from your submission. Again, your best bet is to get indexed in the Open Directory project.</p> <p><img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://searchservices.lycos.com/searchservices/select_overview.asp" target="_blank">Submit to Lycos here</a></p> <p><img src="http://www.entheosweb.com/images/search_engines/msn_logo.gif" alt="MSN Search Engine" width="75" height="32" /><br /> Enter your URL, e-mail, site name and site description to submit your site.</p> <p><img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.submit-it.com/msnsubmit.htm" target="_blank">Submit to MSN here</a></p> <p><img src="http://www.entheosweb.com/images/search_engines/fast.gif" alt="Fast Search Engine" width="90" height="31" /><br /> Enter your URL, category and e-mail address to submit your site. The Norwegian company behind FAST Search also powers some of the results that appear at Lycos </p>Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-87317595100397140792008-12-11T03:07:00.001-08:002008-12-23T01:17:25.194-08:00Website Promotion Tips and Advice<h1><br /> <!-- #EndEditable --></h1><!-- #BeginEditable "content" --> <p> </p><table align="right" border="0" cellpadding="0" cellspacing="1"> <tbody><tr> <td><script type="text/javascript"><!-- google_ad_client = "pub-1148387067248465"; /* 300x250, created 11/19/08 */ google_ad_slot = "5692836953"; google_ad_width = 300; google_ad_height = 250; //--> </script> <script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script><script>window.google_render_ad();</script><iframe name="google_ads_frame" src="http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-1148387067248465&dt=1228993635866&lmt=1228993635&prev_slotnames=0607187128&output=html&slotname=5692836953&correlator=1228993635792&url=http%3A%2F%2Fwww.entheosweb.com%2Fwebsite_promotion%2Fpromotion_tips.asp&ea=0&ref=http%3A%2F%2Fwww.entheosweb.com%2Fwebsite_promotion%2Fdefault.asp&frm=0&ga_vid=1639725682.1228993374&ga_sid=1228993374&ga_hid=551790059&ga_fc=true&flash=10.0.12&u_h=1024&u_w=1280&u_ah=994&u_aw=1280&u_cd=32&u_tz=330&u_his=2&u_java=true&u_nplug=14&u_nmime=61&dtd=2" marginwidth="0" marginheight="0" vspace="0" hspace="0" allowtransparency="true" scrolling="no" width="300" frameborder="0" height="250"></iframe></td> </tr> </tbody></table> After trying out various strategies, tips and tricks given in many promotion sites we've come up with a few important tips and advice that have worked well for us. These tips would help you get a better listing, position and ranking in the popular search engines. They are simple to follow and are guaranteed to give you good results. Lets go through them right now! <ol class="bullet2"><li><span class="subtitle">Quality Site with Quality Content</span><br /> The first and most important rule is to promote quality sites. Don't waste your time promoting junk sites. It won't pay off in the long run. This is honest talking here. You must be willing to spend time developing a quality website, if you want your promotion efforts to pay off. The first month you won't do too well but as you keep adding new pages, getting new links and updating your site you will see your hits increasing over the months. Your site will get more traffic as time goes by. Also don't underestimate the importance of small websites. Once they come to your website and they like what they see they will usually link to you with a good review. I can't emphasize enough on building a quality website. If you have a good website you will definitely get a lot of traffic over time.<br /> <span class="redtext"><br /> Important Tip:</span> While we are on the subject of content here's a very important tip - Try to come out with something <b>original</b> or slightly different from what your competitors are coming out with. Write articles related to your field of experience and focus it on specific topics. For e.g. If we were to write on 'website promotion', we would have thousands of sites competing with us in the search engines. Whereas if we were to write on 'website Promotion Tips and Advice' we would have a better chance of ranking high in the search engines. Now visitors would come to this page and through this page they may go to our website promotion page or services page. The idea is to write something a little different from the norm to draw visitors to your site. There's no use writing a great article on what others have already written about. It will only be lost in the search engines.<br /> <br /> I'd like to share a personal experience here. When we first launched Entheos I wrote this entire website promotion guide on very generic and common keywords. I made these great pages on search engine submission, meta tags, link popularity etc. - keywords I was sure people would search for. What I didn't realize was that there were thousands of sites offering what I had written about, as a result of which my pages never came up in the first few pages of search engines. Though they were good pages they failed to bring traffic to Entheos. I then changed my strategy and wrote articles on slightly different topics - like <a href="http://www.entheosweb.com/website_promotion/google.asp">Google Tips 'n' Tricks</a>, <a href="http://www.entheosweb.com/website_promotion/altavista.asp">Altavista Tips</a> and boy did we do well in the search engines. They got the 1st position in the search engines and resulted in an increase of traffic. I wrote these articles because I just learnt of some new tips after a lot of experimentation and research and I was just dying to share them - the rest is history!<br /> <br /> </li><li><span class="subtitle">Meta Tags </span><br /> While <a href="http://www.entheosweb.com/website_promotion/metatags.asp">preparing your meta tags</a> don't use generic or common keywords, try to use a combination of keywords and see if you can make them different from your competition. This would give you a better chance with the search engines. Try to come out with something different and you'll probably do pretty well. <span class="redsubtitle"><br /> Tip:</span> The golden rule for effective search engine submission is that all your important keywords should appear in your title, description, content and alt tags of your web page. This increases your keyword density and helps in boosting your ranking with the search engines.<br /> <br /> </li><li><span class="subtitle">Concentrate on the Big Search Engines</span><br /> Google is my favorite search engine so I've really been concentrating on our listing, ranking and links here. Its brought us the most amount of traffic (more than 40 times the other search engines - no kidding!). Google brings in a lot of traffic because it takes keywords from the content as well as the meta tags resulting in a good chance of getting ranked high when searching for unique keywords. Also it gives a lot of importance to link popularity so getting many quality sites to link to yours can get rid of a lot of unwanted competition. Focus on the search engines that are sending you the most amount of traffic - understand their strategies, study their sites, visit forums and get as much of information as you can to tackle them. Contrary to popular belief Excite, Lycos, HotBot, Direct Hit don't send much traffic. Google by far is the Best.<br /> <br /> </li><li><span class="subtitle">Get Like-minded Sites to Link to You</span><br /> This is the key to high search engine ranking and placement. <a href="http://www.entheosweb.com/website_promotion/link_popularity.asp">Link Popularity</a> means how many sites link to you. The idea behind link popularity is that other sites will link to you only if you are a quality site offering quality resources. Google uses this concept while ranking websites. Get quality sites to link to you and you will get a good ranking in Google. This is also a great way to bring traffic to your site. Usually sites that link to us send us more traffic than the popular search engines.<br /> <br /> </li><li><span class="subtitle">Be Patient - Traffic increases over time</span><br /> Be patient. Don't expect miracles to happen overnight. Promotion is a continuous process. You need to continue to update your site, add new articles and resubmit to search engines. Over time you will see your site coming up in search engines, getting better placement and sending you more visitors. Check your ranking every month. Be involved in the promotion process. Check your <a href="http://www.entheosweb.com/website_promotion/web_site_statistics.asp">website statistics</a> to see which sites are sending you the most traffic. Work on getting new sites to link to you. Tweak the pages that are not sending you any visitors. </li></ol>Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-17159552821777515712008-12-11T03:06:00.000-08:002008-12-23T01:17:25.194-08:00Search Engine Submission, Ranking, Link Popularity and More<h2><br /></h2> <p>Web site promotion is the most important step in making your business succeed online. To help you promote and maintain your web site, we have dedicated a whole section of our web site to site promotion. We hope that you will find these articles, guidelines and tips useful. </p> <p>Some people mistakenly believe that as soon as a site is on the Internet, the search engines will automatically index their site and people will start visiting their site from Day 1. This is not true. Once your site is live (i.e. uploaded and accessed through the Internet) you need to concentrate on web site promotion. This is the step that will really give you a powerful Net presence. It's easy and it's fun so let's jump right into it.</p> <h2>Let's start with the basics </h2> <p>There are many methods that you can use to promote your web site. But one rule remains the same. Make sure that your web site is <b>100% ready</b> to be submitted before you begin with promotion. You don't want to give anyone a chance of rejecting your web site and you don't want to disappoint visitors who come to your site.</p> <ol class="bullet2"><li><span class="subtitle">Submitting to Search Engines</span><br /> <br /> The first and most important method of promotion is submitting your web site to search engines and directories. The webmaster fills out a form that tells the search engine or editor (in case of a directory or site) to visit and index the suggested site. <br /> <br /> <ol class="bullet2"><li><a href="http://www.entheosweb.com/website_promotion/metatags.asp" class="subtitleorg">Preparing your web pages - Meta tags</a><br /> You must submit your web site only after you have prepared your web pages for the search engines. This means you have to insert appropriate meta tags on all your web pages (keywords, description and title).<br /> <img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.entheosweb.com/website_promotion/metatags.asp">Preparing your web pages for effective web site promotion leading to high search engine ranking</a><br /> <br /> </li><li><b><a href="http://www.entheosweb.com/website_promotion/web_site_optimization.asp" class="subtitle">Web site Optimization</a></b><br /> For your site to score high with search engines, you will need to optimize your web site (improve your HTML, load time, browser compatibility and other factors to cater to search engines). Only after optimization should you submit your site.<br /> <img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.entheosweb.com/website_promotion/web_site_optimization.asp">Web Site Optimization - Using Free Web Site Analysis Software to improve your site </a><br /> <br /> </li><li><b><a href="http://www.entheosweb.com/website_promotion/search_engine_submission.asp" class="subtitle">Finally, it's time to submit!</a></b><br /> After optimization, it's time to submit your site. We recommend submitting to all the major search engines, since search engines generate approximately 90% of web site traffic. Top search engines have a form for site suggestions. A link to this form can usually be found from the home page; it may say "Add a site" or "Suggest a URL." You can jump to our article which has links to all submission forms and tips on submission, so you don't have to spend hours looking for them.<br /> <img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.entheosweb.com/website_promotion/search_engine_submission.asp">Click here to see a list of major search engines and their submission pages</a><br /> <br /> </li></ol> </li><li><span class="subtitle">Submitting to Directories</span><br /> Once you have submitted your web site to all the top search engines, it is time to submit your site to the important directories, like Yahoo, Looksmart, AOL etc. Submitting to Directories is different from submitting to Search Engines as human editors review your site and accept or reject your site according to its quality. Before submitting to Directories, you need to make sure that your site is 100% ready. You also need to carefully follow their guidelines while you submit your site.<br /> <img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.entheosweb.com/website_promotion/directory_submission.asp">Click here to read more about submitting your web site to directories.</a><br /> <br /> <span class="subtitleorg">Note:</span> There are a number of <a href="http://www.entheosweb.com/website_promotion/free_promotion_software.asp">free search engine submission tools</a> available but I suggest that the first time you submit your web site, do it manually. And <b>never use these free tools while submitting to Directories</b>. This must be done manually. Don't worry, submitting to search engines is very easy. It's only preparing your web pages with the appropriate meta tags that takes time.<br /> <br /> </li><li><span class="subtitle">Other Internet Marketing Techniques</span><br /> You need to know that web site promotion is an ongoing process, as there are thousands of web sites being added every day and the competition is getting tougher by the minute! Most of the sites listed on the search engines are getting lost as there may be 100 -10,000 other web sites in the same field. We all know that <b>most people don't look at more than 2-3 search result page</b>s. The web sites that are not found in these pages are lost in the competition. New promotion techniques are coming out every day to get around this problem. We will discuss these new promotion techniques soon. Some of them are as follows:<br /> <br /> <ol><li><a href="http://www.entheosweb.com/website_promotion/link_popularity.asp" class="subtitle">Link Popularity</a><br /> This is a very important Internet marketing technique which is rapidly gaining importance. The term "link popularity" refers to the number of sites that are linked to your site. Search engines check your link popularity and based on how popular your site is, give you a higher ranking. Try getting as many quality links as possible to <b>boost your search engine position. </b><br /> <img src="http://www.entheosweb.com/images/icons/arrow.gif" width="8" height="8" /> <a href="http://www.entheosweb.com/website_promotion/directory_submission.asp">Read more about link popularity and ranking high in the search engines.</a><br /> <br /> </li><li><span class="subtitle">Writing Quality Articles</span><span class="subtitleorg"><br /> </span>Get visitors flocking to your site by writing quality articles. Write articles that are related to the content of your site. Most people come to the Internet for quality information. Articles build your credibility and reputation and your visitors may use your services in the long run. You also get more links to your sites through this method.<br /> <br /> </li><li><span class="subtitle">Publish your own ezine or newsletter</span><span class="subtitleorg"><br /> </span>Ezines (or e-mail newsletters) are the latest buzz for marketing on the Internet. Everyone is talking about how you should publish your own ezine to increase traffic, hits and sales. Popular ezines usually give current information and resources that will keep subscribers informed and updated. Ezines are also a great way to keep in touch with your visitors. <br /> <br /> </li></ol> </li><li><span class="subtitle">More Internet Marketing Tips Coming Soon!</span> We will continue to update this page so don't forget to bookmark it for your future web promotion endeavors.</li></ol>Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-78056501485697218402008-11-22T06:24:00.001-08:002008-12-23T01:17:25.194-08:00PIPING DESIGN QUESTIONSimple<br />1. What is the ASME code followed for design of piping systems in Process<br />pipings (Refineries & Chemical Industries)?<br />(i) B31.1<br />(ii) B31.3<br />(iii) B31.5<br />(iv) B31.9<br />Answer (III)<br />2. What do you mean by following items?<br />i. )ISLB-400 ii) ISMB-600 iii) ISHB-350 iv) ISMC-300 v) ISJB-150 vi) ISLB-200<br />vii)ISMB-450 viii)ISWB-400 ix) ISJC-200 x) ISLC-350 xii) ISMC-250<br />Answer:<br />i. Indian STD light weight beam, Web size – 400<br />ii. Indian STD medium weight beam, Web size – 600<br />iii. Indian STD ‘H’ beam, Web size – 350<br />iv. I ndian STD medium weight channel, Web size –300<br />v. I ndian STD junior beam, Web size – 150<br />vi. Indian STD light weight beam, Web size – 200<br />vii. Indian STD medium weight beam, Web size – 450<br />viii. Indian STD wide flange beam, Web size – 400<br />ix. Indian STD junior channel, Web size – 200<br />x. I ndian STD light weight channel, Web size – 350<br />xi. I ndian STD medium weight channel, Web size – 250<br />3. What is this item?<br />i. ISA-100X100X12 ii) ISA-80X50X10 iii)ISLT-100X100<br />Answer:<br />i. Equal angle size 100x12 THK<br />ii. Unequal angle size 80x50x10 THK<br />iii. Indian STD light weight tee bar size 100x100<br />4. What is the difference between stub in and stub on branches? Describe with<br />sketch.<br />Which one is preferred?<br />For branching of one size lesser of run pipe, Stub On is preferred. For other branching<br />less than one size of run pipe stub in is preferred. The Design is based on ANSI B 31.3<br />5. What is the difference between Pipe and Tube?<br />Ans: Pipe is identified by NB and thickness is defined by Schedule whereas Tube is<br />identified by OD.<br />6. From which size onwards NB of pipe is equal to OD of Pipe?<br />Ans: From the size 14” and onwards NB = OD of pipe.<br />7. Write down the outside diameter of following pipe?<br />i. 3 inch ii) 6 inch iii) 10 inch iv) 14 inch<br />Answer:<br />i. 3 inch = 88.9mm ii)6 inch = 168.28mm<br />iii) 10 inch = 273.06mm iv) 14 inch = 355 mm(OD= Size X 25.4)<br />8. What is the difference between machine bolt and stud bolt?<br />Answer:<br />Machine bolt has a head on one side and nut on other side but stud bolt have nuts on<br />both sides.<br />9. What is soluble dam?<br />Answer:<br />Soluble dam is a water-soluble material used for restricting the purging gas within the<br />pipe.<br />10. While welding of pipe trunion to pipe/reinforcement pad you have to put a hole<br />or leave some portion of welding why?<br />Answer:<br />For venting of hot gas which may get generated due to welding<br />11. What do you mean by following type of welding<br />i. SMAW ii)TIG<br />Answer:<br />ii. SMAW = SHIELDED METAL ARC WELDING<br />iii. TIG = TUNGSTEN INTER GAS WELDING<br />12. Find out the elevation of marked point ‘A’<br />Answer:<br />Elevation of marked point ‘A’ is 100.050<br />13. What should be the radius of long radius elbow?<br />Answer:<br />1.5D (Where “D” is the diameter of the pipe)<br />14. Normally where do we use the following?<br />i. Eccentric reducers ii)Concentric reducers<br />Answer:<br />i. Eccentric reducers = Pump suction to avoid Cavitation, To maintain elevation (BOP) in<br />rack.<br />ii. Concentric reducers = Pump discharge, vertical pipeline etc.<br />15.Concentric reducer is used in pump suction. (Yes / No). Explain.<br />Answer:<br />No. Air pockets may form if concentric reducer is used at pump suction, which results in<br />Cavitation, and cause damage to Pump. To avoid this problem, Eccentric Reducer with<br />Flat Side Up (FSU)is used in Pump Suction.<br />16. What do you mean by Cavitation in Pump?<br />A pump is designed to handle liquid, not vapour. Vapour forms if the pressure in the<br />pump falls below the liquid’s vapour pressure . The vapour pressure occurs right at the<br />impeller inlet where a sharp pressure drop occurs. The impeller rapidly builds up the<br />pressure which collapses vapour bubbles causing cavitation and damage . This is<br />avoided by maintaining sufficient NPSH.<br />(Cavitation implies cavities or holes in the fluid we are pumping. These holes can also<br />be described as bubbles, so cavitation is really about the formation of bubbles and their<br />collapse. Bubbles form when ever liquid boils. It can be avoided by providing sufficient<br />NPSH.)<br />17. What do you mean by NPSH? How do you calculate it?<br />W.P EL. “A”<br />W.P.EL –100.050<br />3 ∅Pipe<br />5000<br />50<br />Slope 1:100<br />NPSH: Net Positive Suction Head. NPSH is the pressure available at the pump suction<br />after vapour pressure is substarcted.<br />It is calculated as : Static head + surface pressure head - the vapor pressure of your<br />product - the friction losses in the piping, valves and fittings.<br />It thus reflects the amount of head loss that the pump can sustain internally before<br />vapour pressure is reached.<br />18. What is the ASTM code for the following?<br />i. CS pipe ii) CS fittings iii)CS flanges iv)AS pipe P5/P11 v)Cast CS Valves<br />Answer:<br />i. CS pipe = A106 Gr.B<br />ii. CS fittings = A234 Gr.WPB/WPBW<br />iii. CS flanges = A105<br />iv. AS pipe = A335 Gr P1/P11<br />v. Cast CS Valves = A216 Gr.WCB<br />19. What is the thumb rule to calculate spanner size for given bolt?<br />Answer:<br />1.5 x diameter of Bolt<br />20. What is the thumb rule to calculate Current required for Welding?<br />Answer:<br />Current (Amp) = [ Diameter of Electrode (mm) X 40] + 20<br />21. What is steam tracing? How do we decide the location of SSM & CRM.<br />Answer:<br />Steam Tracing is a process which is used to prevent the fluid passing through a<br />process line from freezing by keeping the temperature high enough for free flow of fluid<br />and thus maintaining pumpability.<br />SSM and CRM are generally located 38M max for open system and 24 M max for<br />closed system when we use LP Steam up to 3.5 kg/sq cm. as a heating media.<br />22. Which piping items will you drop down before conducting Flushing and<br />Hydrotest?<br />Ans: Items like Control Valve, Orifice plates, Rotameters, safety valves , Thermowells<br />are dropped or replaced with temporary spools before hydro test.<br />23. Why do we provide a Dampner in the Piping of Reciprocating Pump?<br />Ans: To take care of Pulsation.<br />24.Why do we provide Full Bore Valve in connecting pipeline of Launcher /<br />Receiver?<br />Ans: For Pigging.<br />25. Which parameters will u check during checking Piping Isometrics?<br />Ans: Bill of Material, Pipe Routing wrt GAD, Supporting arrangement , details of<br />insulation, hydrotest pressure, painting specs and provision of Vent and Drains at<br />appropriate locations.<br />26. What is the ANSI/ASME dimensional standard for steel flanges & fittings?<br />(i) B16.3<br />(ii) B16.5<br />(iii) B16.9<br />(iv) B16.10<br />Answer (II)<br />27. How can flanges be classified based on facing?<br />a. Flat Face b. Raised Face c. Tongue and groove d. Ring type joint<br />28. What do you mean by AARH (Flange Finish)?<br />Ans: Arithmetic Average Roughness Height.<br />29. Which are the different types of Gaskets?<br />Ans: Full Face, Spiral Wound, Octagonal Ring Type, Metal Jacketed and Inside Bolt<br />Circle.<br />30. What should be the relative hardness between the RTJ gasket and flange<br />groove<br />Ans: For a RTJ flange , the joint ring should have a 30-40 Vickers hardness less than<br />that of the mating face of flange.( Brinnel hardness for RTJ groove shall be 20-50 BHN<br />more than the corresponding gasket hardness)<br />31. From which side of pipe will you take a branch connection?<br />Ans: When Fluid is Gas, Air or Steam and Cryogenic Service – Topside.<br />When Fluid is Liquid – Bottom Side.<br />32. Why don’t we take a branch for Cryogenic Service from bottom side though the<br />fluid is in liquid state?<br />Ans: There is the chance of Ice formation during normal operation and since ice flows<br />from the bottom of the pipe it will block the branch pipe connection.<br />33. Why do we provide Drip Leg in Steam Line?<br />Ans: To remove Condensate when there is a rise in the pipe along the flow direction. If<br />we do not provide the drip leg in steam line, the condensate which forms inside the pipe<br />will result in Water Hammer effect causing damage to piping system.<br />34. How do you support any small size HDPE/PVC (Plastic) pipe?<br />Ans: It should be supported continuously by using channel or Angle so that line should<br />not Sag or fall from the sleeper/rack due to uneven expansion because of Hot Temp.<br />35. Why do we provide High Point Vent (HPV) and Low Point Drain (LPD) in piping?<br />Ans: HPV – for removing Air during Hydro-test.<br />LPD – for draining water after conducting Hydro-test.<br />36. Which standard and codes will you refer while designing the piping?<br />Ans: Following are the codes and standards –<br />ASME SEC I : Rules for construction of Power Boilers.<br />ASME SEC VIII : Rules for construction of Pressure Vessels.<br />ASME B 31.1 : Power Piping<br />ASME B 31.3 : Process Piping<br />ASME B 31.4 : Pipeline Transportation system for liquid hydrocarbon and<br />other liquids.<br />API RP 520 : Sizing selection and installation of Pressure Relieving<br />Devices in refineries<br />API Std 610 : Centrifugal Pumps for Petroleum, Heavy Duty Chemical and<br />Gas Industry Services.<br />ANSI/NEMA SM 23 : Steam Turbines for Mechanical Drive Services.<br />API Std 617 : Centrifugal Compressor for Petroleum, Chemical and Gas<br />Industry Service.<br />EJMA : Expansion Joints Manufacturer’s Association.<br />OISD – 118 : Layout for Oil and Gas Installations.<br />IBR : Indian Boiler Regulations.<br />NACE MR – 0175 : Sulfide Stress Cracking Resistant Metallic Materials for Oilfield<br />Equipment.<br />NACE MR – 0284 : Evaluation of Pipeline and Pressure Vessel Steel for<br />Resistance to Hydrogen Induced Cracking.<br />NACE TM – 0177 : Laboratory Testing of Metals for Resistance to Sulfide Stress<br />Cracking in H2S Environment.<br />37. What do you mean by IBR and Which lines comes under IBR purview?<br />Ans: IBR: Indian Boiler Regulation Act.<br />Steam lines with conditions listed bellow comes under IBR purview –<br />Lines for which design pressure is 3.5 kg/sq cm and above.<br />Line size above 10” having design pressure 1.0 kg/sq cm and above.<br />Boiler feed water lines to steam generator, condensate lines to steam generator and<br />flash drum.<br />38. What are Weldolet and Sockolet? And where they are used?<br />Ans: Weldolet and Sockolet are basically self reinforced fittings.<br />Weldolet is used for Butt weld branch connection where standard tee is not<br />available due to size restrictions and the piping is of critical / high pressure service.<br />Sockolet is used for socket welding branch connection, which require reinforcing<br />pad.<br />39. What is the MOC for Superheated high pressure Steam Lines?<br />Ans: A 335 Gr P I / P II<br />Composition : 0.5 Mo(P1) /1.25 % Cr-.5 Mo(P11)<br />40. What is the normal upstream and downstream straight length of orifice flow<br />meter?<br />Answer : Upstream - 15D Downstream - 5D<br />41. What are the essential data required for the preparation of equipment layout?<br />Ans : 1)PFD and P&ID 2. Project Design data 3. Equipment Sizes & Buildings<br />42. What are the various statutory requirements to be considered during layout?<br />State Industrial Development Corporation (SIDC)<br />Central / State Enviromental Pollution Control Boards (PCBS)<br />Factory Inspectorate<br />State Electricity Boards<br />Chief Controller of Explosives (CCOE)<br />Static & Pressure Vessel Rules (SMPV)<br />Tariff Advisory Committee<br />Aviation Laws<br />Chief Inspector of Boilers (CIB)<br />Oil Industry Directorate (OISD)<br />Food and Drug Administartion (FDA)<br />Ministry of Environment and Forest (MoEF)<br />43. What do you mean by Composite Flange?<br />The flange that is made up of more than one MOC is called a Composite flange.<br />a. Lap Joint Flanges<br />Insert Flanges are a specialty in the arena of pipe size flanges and consist of two parts<br />- the insert and the flange ring. The flange ring is the outer part of the insert flange<br />assembly, containing the bolt holes.<br />The two piece construction of the insert flange also offers the economy of matching the<br />insert material to the process pipe (usually some corrosion resistant alloy) while the<br />outer flange ring may be manufactured from steel. When the environment req uires the<br />flange ring to be made of some alloy the rotating feature is still maintained.<br />b. RF flanges with Raised of one MOC and rest of the flange with different MOC<br />c. RF blind flange with an overlay of 90/10 Cuni for Sea water service.<br />44. What do you mean by Insulated Joint?<br />Ans: Insulating Joints are a prefabricated, non<br />separable union used to isolate specific sections of<br />Pipelines to prevent corrosion caused by stray<br />electrical currents or interference from other<br />pipelines and power transmission cables.<br />45. What are Insulating Gasket Kits?<br />Ans: Insulation gasket kits are designed to combat the effects of corrosion often found<br />in flanged pipe systems. Galvanic corrosion between dissimilar metal flanges (flow of<br />currents) , flange insulation associated with cathodic protection of underground piping<br />are also the places where Insulating gasket kits are used. It consists of<br />Gasket Neoprene faced Phenolic /Glass Reinforced<br />Epoxy(G10)<br />Insulation sleeve Reinforced Phenolic/Nylon/Polyethylene/(G10)<br />Insulation washer Reinforced Phenolic/Nylon/Polyethylene/(G10)<br />Plated Washer Electro plated steel washer<br />46. What do you mean by Jacketed Piping?<br />Ans:<br />47. What is the min. distance to be maintained between two welds in a pipe<br />The rule of thumb is that the minimum distance between adjacent butt welds is 1D. If<br />not, it is never closer than 1-1/2". This is supposedly to prevent the overlap of HAZ s.<br />Minimum spacing of circumferential welds between centrelines shall not be less than 4<br />times the pipe wall thickness or 25 mm whichever is greater.<br />48. What are the different hardness tests carried out?<br />Ans:<br />Brinell Hardness Test<br />Rockwell Hardness test<br />Vicker Hardness Test<br />49. What is the relation between Brinell Hardness No and Rockwell Hardness<br />No?<br />Ans:<br />22 HRC (Rockwell Hardness) = 238 BHN (Brinell Hardness No)<br />Harder<br />Piping which is recognized as providing the most<br />uniform application of heat to the process, as well<br />as maintaining the most uniform processing<br />temperatures where steam tracing is not capable of<br />maintaining the temperature of fluid constant.<br />Usually used for molten sulphur, Polymers service.<br />1.During fabrication you observed that one small crack has appeared on a fresh<br />plate, what type of measure you will take to obtain desired quality with minimum<br />wastage?<br />Answer:<br />First identify the exact length of crack by DP test. Drill on the end point to resist further<br />crack. Remove the crack portion by cutting the strip.<br />2. ISOMETRIC :-<br />i. What are the fittings required for fabrication of the isometric.<br />ii. Find out the length of pipe required.<br />iii. Do joint numbering and show the following things in the isometric.<br />a) Shop joint<br />b) Field joint<br />c) Spool no<br />674<br />2000<br />Drilling Point<br />Crack<br />N 173884<br />EL +104280<br />EL +103530<br />EL +102630<br />N 1736500<br />E 3182000<br />2”<br />Field Joint<br />Shop Joint<br />750<br />Answer:<br />2 INCH ELBOW – 4NOS<br />2 INCH WNRF FLANGE – 2NOS<br />2 INCH GATE VALVE – 1NO<br />2 x 1 INCH CONC. REDUCER – 1NO<br />1 INCH ELBOW 90 DEG – 1 NO<br />2 INCH PIPE - 4.210 MTRS<br />1 INCH PIPE – 1.424 MTRS<br />3. Describe different types of destructive and non-destructive tests?<br />Answer:<br />DESTRUCTIVE TEST: Bend test, Tensile test, Impact test, and Hardness test.<br />NON-DESTRUCTIVE TEST: DPT, MPT, Radiography and ultrasonic test<br />4. What is mean by ‘PWHT’? Why it is required?<br />Answer:<br />“POST WELD HEAT TREATMENT” This is done to remove residual stress left in the<br />joint which may cause brittle fracture.<br />5. What is the minimum thickness of pipe that requires stress relieving to be<br />done as per B31.3?<br />Ans: 19 mm thk.<br />6. What is the difference between Thermostatic and Thermodynamic Steam Trap?<br />Ans: Thermostatic Trap is actuated by Temp differential and is economic at steam<br />pressure less than 6 PSI. It is operated by the movement of liquid filled bellows or by<br />bimetal element which may get damaged by Water Hammer.<br />Thermodynamic traps are most suited to applications where the pressure downstream<br />of trap is always less than about ½ the upstream pressure. These are suitable for<br />pressure higher than 8 PSI. Water hammer doesn’t affect it.<br />7. What is the Code for Sour Service?<br />Ans: Code for Sour Service is NACE (NACE MR – 0175)<br />NACE: National Association of Corrosion Engineers.<br />8. How much should be the pressure for Hydro-Test?<br />Ans: Hydrotest pressure should be calculated as follow excecpt as provided against<br />point no-4.<br />1. 1.5 Times of Design Pressure.<br />E 3180600<br />E 3181400<br />1” line<br />2. For a design temperature above the test temperature, minimum test pressure can<br />be calculated as:<br />Pt = ( 1.5 X P X St ) / S<br />Where:-<br />Pt: Minimum Test Pressure.<br />P : Internal design pressure.<br />St: Allowable stress at test temperature.<br />S : Allowable stress as design temperature.<br />( see SE in table A-1 or S in table B-1/2/3).<br />3. If a test pressure as per above would produce a stress in excess of the yield<br />strength at test temp. the test pressure may be reduced to maximum pressure that will<br />not exceed the yield strength at test temp.<br />4. If the test pressure of piping exceeds the vessel pressure and it is not considered<br />practicable to isolate piping from vessel, the piping and vessel may be tested together<br />at test pressure of the vessel when approved by owner and provided the test pressure<br />for vessel is not less than 115% of piping design pressure adjusted for temperature as<br />per point no 2.<br />9. How do you calculate the pipe spacing?<br />Ans: Pipe Spacing (mm) = ( Do + Dt ) / 2 + 25mm + Thickness of Insulation (mm).<br />Where: D0 : OD of Small size Pipe (mm).<br />Dt : OD of Flange of Large size Pipe (mm).<br />10. How do you calculate the width of Pipe rack?<br />Ans: W = ( f X n X s ) + A + B.<br />Where: s=<br />f : Safety Factor<br />= 1.5 if pipes are counted from PFD.<br />= 1.2 if pipes are counted from P&Id.<br />n : number of lines in the densest area up to size 450<br />NB<br />= 300 mm ( estimated average spacing )<br />= 225 mm ( if lines are smaller than 250 NB )<br />A : Additional Width for –<br />Lines larger than 450 NB.<br />For instrument cable tray / duct.<br />For Electrical cable tray.<br />s : 300 mm (estimated average spacing)<br />: 225 mm (if lines are smaller than 250 NB)<br />B : future provision<br />= 20% of (f X n X s) + A<br />11. Which fluid is used in Heat Exchanger in shell side and tube side?<br />Ans: Generally corrosive fluid is used from the tube side (as tube can be easily<br />replaced) and cleaner fluid is used from shell side. Sometimes Hot fluid is also used<br />from the shell side.<br />12. What is Reynold’s number and what is the value of Reynold’s number upto<br />which the flow is laminar?<br />Ans: It’s a dimensionless number to classify the nature of flow.<br />Re=_vd/_<br />Where: Re : Raynold’s no.<br />___ass Density of fluid.<br />d : diameter of Pipe.<br />V : average velocity of fluid.<br />__Viscocity of fluid.<br />Flow is laminar upto Re=2100<br />13. What are Glandless Piston Valves. Where these are used?<br />Ans:Glandless piston valves are maintenance free valves used in the steam service.<br />14. How do you carry out Estimation?<br />Ans:<br />1. Input from Bid:-<br />P&Id, Line list, Temperature, Pressure.<br />Overall Plant Layout and Piping corridor plan.<br />Scope of work and the Specifications for the Job.<br />Specifications for materials like PMS and VMS.<br />2. Value Addition:-<br />Items like Valves, Flanges, Speciality items, Reducers can be estimated from P&Id.<br />Length of Pipes, Elbows, Width of Pipe Rack can be estimated by referring P&Id<br />and Overall Plot Plan.<br />No of Tires (on rack) can be estimated by referring the spacing required for pipes<br />and also the space available.<br />MTO for Steam Traps, Valves (for Vent and drain) can be calculated by using<br />Thumb Rules.<br />3. Loads:-<br />Hydro Test Loads: Can be estimated by assuming all the Pipes (on a grid) empty<br />except some bigger size lines filled with Water.<br />Actual Operating Loads: Gas lines to be considered as empty and rest of the lines<br />to be considered as filled with the Fluid (which they are suppose to carry in<br />operating condition).<br />The loads which ever is higher from above two cases should be referred for<br />structural loading.<br />Stress<br />1. What is the objective of stress analysis?<br />Answer :<br />1. To ensure that the stresses in piping components in the system are within<br />allowable limits<br />2. To solve dynamic problems developed due to mechanical vibration, fluid<br />hammer, pulsation, relief valves, etc<br />3. To solve problems associated due to higher or lower operating temperature such<br />as a) Displacement stress range b) Nozzle loading on connected equipments c) Pipe<br />displacements d) Loads & moments on supporting structure<br />2. What are the steps involved in stress analysis (or any stress package carries<br />out)?<br />Answer :<br />1. Identify the potential loads that the piping system would encounter during the life<br />of the plant<br />2. Relate each of these loads to the stresses and strains developed<br />3. Get the cumulative effect of the potential loads in the system<br />4. Decide the allowable limits the system can withstand without failure as per code<br />5. After the system is designed to ensure that the stresses are within safe limits<br />3. What are the different types of stresses that may get generated within pipe<br />during normal operation?<br />Ans: Axial Stresses (Tensile / Compressive), Shear Stresses, Radial Stresses, Hoopes<br />Stresses.<br />4. How are the loads classified in stress analysis package?<br />Ans : a. Sustained Loads 2. Occasional Loads 3. Displacement Loads (Self limiting<br />stresses due to thermal effects)<br />What are the Inputs for stress analysis of a piping system<br />i) Pipe Size ii) Fluid Temperature iii) Pipe Material<br />iv)Design pressure v)Insulation Thickness<br />vi)Specific gravity vii)Friction coeff. viii) Model<br />5. What are the sources of sustained loads generated in piping system?<br />Ans a. Pressure b. Dead weight of Pipe and attachments<br />Sustained load is calculated as<br />Weight of Pipe with Fluid + Pressure load + Load due to springs<br />W+P1<br />6. How do you calculate the operating load?<br />W+P1+T1<br />T1 – Load due to thermal expansion<br />7. Give some Examples for occasional Loads.<br />Wind, wave & earthquake<br />8. Mention some of Primary Loads (Have their origin in force)<br />Dead Weight, Pressure, forces due to relief or blowdown, force due to water hammer<br />effects<br />9. Mention some of secondary Loads (Have origin in displacement)<br />Force on piping due to tank settlement<br />Vessel nozzle moving up due to expansion of vessel<br />Pipe expansion or contraction<br />Vibration due to rotational equipments<br />10. What is the failure theory subscribed under ASME B31.3?<br />(i) Maximum principal stress theory (Rankines Theory)<br />(ii) Maximum Shear Theory<br />(iii) Tresca Thory<br />Answer : (I)<br />11. What are the types of failures encountered in Piping?<br />Answer : 1. Catastrophic Failure 2. Fatigue Failure<br />12. Select the failure stress range for fatigue failure due to thermal expansion as<br />per B31.3<br />(i) (1.6Sc+1.6Sh)f<br />(ii) 0.78 Sh<br />(iii) (1.25 Sc+0.25Sh)f<br />(iv) Sc+Sh<br />Answer : (III)<br />Sc and Sh –Basic Allowable material stress in cold & hot condtions respectively.<br />f ---- is the stress range reduction factor(1 for 7000 cycles<br />13. What is desired life cycle for Piping in operation?<br />Ans: Desired life cycle for Piping in operation is 20 Years (7000 Cycles).<br />The normal no. of cycles for which the displacement or thermal stresses are<br />designed is<br />7000 cycles<br />14. How do you calculate the stress developed due to thermal expansion?<br />Stress developed = E x e/L<br />E – Young’s Modulus<br />e- Increase in length due to thermal expansion<br />L – Original Length of the pipe<br />15. How do you calculate the thermal expansion in a pipe?<br />e= _ x L x Rise in Temperature<br />_ – Co.efficeint of expansion<br />L- Length of pipe<br />16. What do you mean by Stress Intensity Factor (SIF)? Give some examples.<br />Stress Intensity Factor (SIF) is the ratio of maximum stress intensity to normal stress. It<br />is used as safe factor to account for the effect of localised stress on piping under<br />respective loading. In piping it is applied to welds, fittings, branch connections etc<br />where stress concentration and possible fatigue failure may occur.<br />Eg: SIF for Reducer and Weldneck Flange : 1.0<br />SIF for socket weld flange : 1.3<br />17. Which is the Criteria for Pipe Supporting?<br />Ans: Following are the points which should be taken into account for proper supporting<br />–<br />Load of bare pipe + fluid + insulation ( if any ).<br />Load of bare pipe + waterfill.<br />Load of valves and online equipment and instrument.<br />Thermal loads during operation.<br />Steam out condition, if applicable.<br />Wind loads for piping at higher elevation, if required.<br />Forced vibration due to pulsating flow.<br />Bare pipe with size above 12” shall be supported with Pad or Shoe<br />18. What is the basic span of supports for 2”/6”/10”/24” pipe.<br />Answer:<br />Basic Span is 5.5m / 9m / 11.5m / 15m respectively.<br />19. How do we decide the anchor / cross guide and guide for offsite rack piping<br />Answer:<br />Anchor is provided to restrict all the axial and rotational movements of Pipe, whereas<br />Cross Guide is provided to restrict displacements of Pipe along with the axis<br />perpendicular to it’s centreline and Guide is provided to restrict the longitudinal<br />movements of pipes along with it’s axis.<br />20. Define a typical 6D loop supporting details (Anchor/Guide)<br />21. Provision of anchor / cross guide for control valve.<br />22. What are the things to be taken care of while doing pump piping?<br />Answer:<br />Pipe strain may distort equipment alignment, so welding should be done in such a way<br />that the tension in the equipment flange is minimised<br />23. What is the Steam out condition?<br />Ans: Hydrocarbon lines are usually subjected to Steam Out condition and designed<br />and anlysed at low pressure steam design temperature (should be minimum 180<br />degree C) or design temp. whichever is more . Lines having negative design temp. is<br />analysed for both conditions seperately.<br />24. Where do you provide Anchor and Slotted Support of Heat Exchanger?<br />Ans: Anchor support of Heat exchanger is provided on the side from which Tube<br />Bundle will be pulled out for the purpose of Maintenance work also it is based on the<br />growth of the connecting piping as exchanger should grow with the piping.<br />25. What do you mean by Hoop Stresses and how do you calculate it?<br />Ans: Stresses which are generated circumferancially due to the action of Internal<br />pressure of pipe are called as Hoop Stress. It is calculated by<br />Hoop Stress (Sh) = Pdo / 4t<br />Where P = Force Acting from Inside.<br />Do = OD of Pipe.<br />t= Pipe Thickness.<br />26. How does Hoop Stress affect the system?<br />Ans: As per membrane theory for pressure design of cylinder, as long as hoop stress<br />is less than yield stress of Moc, the design is safe. Hoop stress induced by thermal<br />pressure is twice the axial stress (SL). This is widely used for pressure thickness<br />calculation for pressure vessel.<br />27. What is the design standard followed for the calculation of allowable forces /<br />Moments in nozzles of centrifugal compressor & Steam turbines nozzle?<br />For strain sensitive equipment piping to be routed and supported to limit nozzle<br />loadings and moments in equipment within allowable limits furnished by respective<br />vendors or in absence of vendor data API 560/610/615/621/661 & NEMA SM23.<br />NEMA – SM 23 (Referred by API 617) is used for compressor & steam turbine nozzle.<br />28. What is the mill tolerence to be considered for the thickness of pipe during<br />stress analysis as per ASME B31?<br />(i) 1%<br />(ii) 2.5%<br />(iii) 7.5%<br />(iv) 12.5%<br />Answer : iv<br />29. What is the purpose of providing Graphite Pads in supports below shoes?<br />Answer : To reduce the friction factor. The co-efficient of friction for Graphite Pads is<br />0.1<br />30. How is piping to Tank inlet nozzle is supported and why?<br />Ans: Piping to Tank Nozzle is supported with Spring type support (first support from<br />Nozzle) in order to make the Nozzle safe from the loads which occurs due to the<br />displacement of pipe (thermal expansion of pipe / tank material, tank settlement etc).<br />31. What are the two types of flexible spring hangers?<br />1. Constant Spring and 2. Variable Spring<br />32. What is the difference between Variable Spring Hanger and Constant Spring<br />Hanger?<br />Ans: Variables use coiled springs to support a load and allow movement. The<br />resistance of the coil to a load changes during compression, which is why these devices<br />are called "variables". Constant Spring Hanger provides constant support force for<br />pipes and equipment subjected to vertical movement due to thermal expansion at<br />locations where maintaining a constant stress is critical. This constant resistance is<br />achieved by having two moment arms pivoted about a common point. The load is<br />suspended from one of these arms, and a spring is attached to the other. With an<br />appropriate choice of moment arms and spring properties, a resisting force can be<br />provided that is nearly independent of position.<br />Constant support hangers are principally used to support pipes and equipment<br />subjected to vertical movement due to thermal expansion at locations where transfer of<br />stress to other supports or equipment can be critical. The maximum recommended<br />variation according to MSS standard from the operating load is 25% for variable spring<br />hangers. If the variation exceeds 25%, a constant support hanger should be used.<br />The constant resistance to a load is achieved by combining a spring coil with a cam<br />which rotates about a main pivot point. The cam is designed such that the distances<br />from the main pivot changes to compensate for the variable resistance during<br />compression of the coil. The MSS standard provides for a tolerance of 6% in the<br />constant load through the travel range. Constant support hangers are designed per<br />MSS, ANSI, and ASME standards.<br />The sizing of constants primarily depends on the total travel and load.<br />33. How much should be the difference between the load which will be taken by<br />Variable Spring Hanger during Cold and Hot condition of Pipe?<br />Ans: It should be Maximum 25% of Load for which Spring is designed.<br />34. Differentiate between static load and dynamic load.<br />Ans: A piping system may respond far differently to a dynamic load than it would to a<br />static<br />load of the same magnitude. Static loads are those which are applied slowly enough<br />that the system has time to react and internally distribute the loads, thus remaining in<br />equilibrium. In equilibrium, all forces and moments are resolved (i.e., the sum of the<br />forces and moments are zero), and the pipe does not move.<br />With a dynamic load—a load which changes quickly with time—the piping system may<br />not have time to internally distribute the loads, so forces and moments are not always<br />resolved—resulting in unbalanced loads, and therefore pipe movement. Since the sum<br />of forces and moments are not necessarily equal to zero, the internally induced loads<br />can be different—either higher or lower—than the applied loads.<br />35. Give different types of dynamic loads with example<br />Ans:<br />1. Random – Wind, Earthquake<br />2. Harmonic – Equipment Vibration, Pulsation, Acoustic Vibration<br />Impulse – Fluid Hammer, relief valve opening, slug flow<br />76. What is Dynamic Analysis and why it is used?<br />Ans: Dynamic analysis is performed for all two phase lines in order to ensure that the<br />line supported is safe from vibrations loads which may occur during normal operation as<br />well as in start up or any upset condition.(Diesel mixed with hydrogen in DHDT process)<br />36. What is WRC 107 / WRC 297?<br />Ans: Localised stresses at Nozzle to Shell is calculated by WRC 107 / 297 and these<br />computed stress values shall be limited in accordance with ASME Sec VIII for Pressure<br />Vessels.<br />37. How to get the Foundation Loads?<br />Ans: Foundation Loads for pipe rack should include the loads of Pipes, Cable Trays<br />and Instrumentation duct at that location and also the design load for future tier shall be<br />full load of the most heavily loaded tier in addition to all other wind/seismic/fraction and<br />piping thermal loads for future pipes.<br />Load of pipes filled with water( Largest of 1st case – During hydrotesting dead<br />weight(wt/m X piperack spacing) of pipes + 2 –3 maximum size pipes filled with water<br />2nd case – Actual commissioned condition except the gas lines ) + Proportionate wt of<br />extra space required by client (normal 30%) + Load of 1 heavily loaded tier + Electrical<br />cables + Instrument duct + Guide load for 50% of lines<br />Guide Load = 0.3X(Dead wt of pipes at including water)<br />The maximum induced thermal loads on the Anchor at the battery limit shall be limited<br />to<br />F in kg <= 150 X NB of pipe in inches (It should be <2 tonnes)<br />M in Kgm <=75 X NB of pipe in inches.<br />Horizontal Load = 0.3 X (Dead wt of pipes including water)<br />This load is used for designing of foundation bolts.<br />Foundation loads for any vessel having agitator mounted on top should contain weight<br />of tank at operating or design condition (whichever is more) plus 20% of it for dynamic<br />loading.<br />38. What is the maximum expansion absorbed in loops in normal design?<br />Ans:10 Inches<br />39. What is the limiting factor in deciding the length of the spool in Jacketed<br />piping?<br />Ans: Force exerted by dissimilar expansion of inner pipe = Force exerted by dissimilar<br />expansion of jacket pipe<br />The stress developed due to this should be within limits as per ANSI B31.3<br />(Also fabrication constraints)<br />40. What is the factor to be checked concerning the expansion of header attached<br />to air cooler piping?<br />Ans: Vendor drawing to be checked to see how much movement is permitted to<br />compensate line expansion. To accommodate the diff. Expansion between inlet and<br />outlet (The inlet temperature >The outlet temperature) offset can be built in to outlet<br />piping to compensate for diff.expansion.<br />Since the tubes are of floating design the nozzle flange is of 150# and loads transferred<br />are to be kept minimum.<br />Since the tubes are of floating design, the nozzle flange is 150#. Load of the nozzle to<br />be kept minimum.<br />41. What is the maximum no. of cell nozzles connected to a single header of air<br />cooler piping header in normal practice?<br />Ans: Six nos.<br />42. What is fluid hammer and how it is generated?<br />Ans: When the flow of fluid through a system is suddenly halted at one point, through<br />valve closure or a pump trip, the fluid in the remainder of the system cannot be stopped<br />instantaneously as well. As fluid continues to flow into the area of stoppage (upstream<br />of the valve or pump), the fluid compresses, causing a high pressure situation at that<br />point. Likewise, on the other side of the restriction, the fluid moves away from the<br />stoppage point, creating a low pressure (vacuum) situation at that location. Fluid at the<br />next elbow or closure along the pipeline is still at the original operating pressure,<br />resulting in an unbalanced pressure force acting on the valve seat or the elbow.<br />The fluid continues to flow, compressing (or decompressing) fluid further away from<br />the point of flow stoppage, thus causing the leading edge of the pressure pulse to move<br />through the line. As the pulse moves past the first elbow, the pressure is now equalized<br />at each end of the pipe run, leading to a balanced (i.e., zero) pressure load on the first<br />pipe leg. However the unbalanced pressure, by passing the elbow, has now shifted to<br />the second leg. The unbalanced pressure load will continue to rise and fall in sequential<br />legs as the pressure pulse travels back to the source (or forward to the sink). The ramp<br />up time of the profile roughly coincides with the elapsed time from full flow<br />to low flow, such as the closing time of the valve or trip time of the pump. Since the<br />leading edge of the pressure pulse is not expected to change as the pulse travels<br />through the system, the ramp down time is the same. The duration of the load from<br />initiation through the beginning of the down ramp is equal to the time required for the<br />pressure pulse to travel the length of the pipe leg.<br />43. What is the purpose of expansion bellows?<br />Ans: Expansion bellows are used absorb axial compression or extension, lateral shear<br />or angular torsion developed in the pipes (specially near nozzles)<br />44. You have to connect a 20” pipe to a manhole of existing tank , how will you<br />go about in carrying out the suitability of the manhole flange.<br />45. What should be the material of shoes for supporting AS pipes & why?<br />Ans: If CS shoes are used Pad in contact with the pipe to be of Alloy steel to avoid<br />dissimilar welding at pipe. To avoid alloy steel welding and dissimilar welding fabricated<br />clamps either of CS or SS can be used.<br />46. What is the allowable stress range for CS pipes.<br />Ans: 2070 kg/cm2<br />47. What are sway braces?<br />Ans: Sway Braces are essentially a double-acting spring, housed in a canister. Unlike<br />variable effort supports, Sway Braces are not intended to carry the weight of pipework;<br />their purpose is to limit undesirable movement. Sway Braces act like a rigid strut until a<br />small preload is reached, whereafter the restraining force increases in proportion to the<br />applied deflection. Fig. 1<br />Undesirable movement can occur due to many phenomena, such as wind loading,<br />sympathetic vibration, rapid valve closure, relief valves opening, two phase flow or<br />earthquake. It may be necessary to limit this type of deflection to prevent the<br />generation of unacceptable stresses and equipment loadings.<br />The Sway Brace is a cost-effective means of limiting pipework deflection. It should be<br />noted however that it does provide some resistance to the thermal movement of the<br />pipework and care should be taken when specifying to ensure that this is acceptable.<br />Installation of Sway Braces will have the effect of raising the fundamental frequency of<br />vibration of a pipework system; this is likely to reduce undesirable deflections. Sway<br />Braces are often used to solve unforeseen problems of resonant vibration. For<br />situations where the resistance to thermal movement provided by Sway Braces is<br />unacceptable, you are referred to Pipe Supports Limited’s range of hydraulic snubbers<br />and dampers.<br />48. Give a typical stress report including input and output and what is interpreted<br />form the output.<br />49. For offshore structures what analysis is performed by Caesar.<br />50. In an offsite pipe rack change in direction during analysis it is found two<br />adjacent pipes are having unequal expansion with the inner pipe having 50 cm<br />thermal expansion. What can be done to eliminate collision during hot condition.<br />Ans: Use Cold Pull technique. Calculate the thermal expansion of the inside pipe, cut an<br />equal length form the elbow joint and then reweld with a shorter length to take care of<br />expansion in hot condition.<br />51. What are the Insulation material used for piping systems.<br />Ans:<br />1. Fibrous – Rock & Glass Wool<br />2. Rigid - Calcium silicate, Polyisocyanurate, cellular GlassSumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-65187000944438387902008-11-22T06:19:00.000-08:002008-12-23T01:17:25.195-08:00Controlling Vessel's And TanksINTRODUCTION.<br /><br />It would seem that controlling a vessel should be a very simple matter -- They don't really do anything! But then, if they didn't do anything why are there so many of them? And why do they have so many different names? Going through a typical set of Piping and Instrumentation Diagrams (P&IDs) I see the following vessels:<br />• Degassing Drum • Gas Separator • Storage Tank<br />• Feed Flash Drum • Reflux Accumulator • Day Tank<br />• Surge Drum • Suction Scrubber • Slug Catcher<br />• Lube Oil Separator • Head Tank • Deaerator<br />Although each of these is essentially a simple vessel or tank without any special internal structure, each serves a different purpose. Once it is clear what the purpose of a piece of equipment is, and how it functions, it will also be clear how to control and protect it. Different purposes require different controls.<br />SURGE TANKS. The most common function of a vessel or tank is to match two flows that are not identical in time but are expected to average out over the long run. Take a feed surge drum, for example. Flow into the unit is more or less steady but is subject to interruption. The flow to the processing unit should be as constant as possible, avoiding sudden change. Nevertheless, it, too, may be subject to interruption due to downstream conditions.<br />The purpose of the surge drum is to maintain sufficient inventory to feed the process and to maintain sufficient void capacity to continue receiving feed as it arrives. Clearly the tank must be large enough to accommodate any normal discrepancies between input and output over a reasonable period of time. Between the upper and lower bound, the exact value of the level does not matter.<br />Two separate control parameters are implied: Level and flow. Level control is no problem. Greg Shinskey1 refers to "The easy element -- capacity". A high gain, level controller connected to a valve at either the inlet or the outlet will maintain the level very accurately at its setpoint. The only problem with this approach is that it absolutely defeats the purpose of the vessel. The same effect would be achieved by blocking in the vessel and bypassing the inlet directly to the outlet.<br />To control flow alone is also quite simple. A flow controller at the outlet, properly tuned, will maintain a steady flow to the process. Unfortunately, there is nothing to make this flow equal to inflow. It will not even equal the average inflow unless there is something to make it do so.<br />What we need is an instrument that measures the accumulated error between inflow and outflow. The tank itself is that instrument!<br />Level = Starting Level + ∫ (Inflow - Outflow) dt / Tank Area<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-1<br />(To a process controls engineer, every piece of equipment is just a big, non-tuneable instrument!) The level transmitter only transmits the process value to the control system. If we now cascade the output of the level controller to the flow controller, we have a system that has one process variable: Accumulated flow imbalance. It has only one point of control: Outflow to the process.<br />Surge Drum Control<br />To start this simple process:<br />• Fill the tank about half full.<br />• Give the level controller the current level as its set point. (PV tracking does this automatically.)<br />• Switch the flow controller to automatic with an estimated average flow as its setpoint.<br />• Switch the flow controller to cascade.<br />• Switch the level controller to automatic.<br />The control system will keep the flow "constant" but that constant varies in response to the imbalance between outflow and inflow. It is not important that the initial estimate of average flow be exact. A low guess will result in the tank level rising a little. A new, higher, estimate will result and the outflow will be adjusted accordingly. In the long term the average flow out is not an independent variable at all. It will be exactly equal to the average flow in. This can be accomplished at any arbitrary tank level. The level setpoint is based on the operator's estimate of the nature of the flow interruptions and whether the most probable upset will require additional flow or void capacity.<br />Should a pump be necessary to transfer the liquid from the vessel to its destination it should be placed between the vessel and the flow measurement. Further information on the control of pumps is found in Controlling Centrifugal Pumps2. This article also includes a section titled "On/off Control" for less critical level applications.<br />There is a long discussion on the special requirements for level control of steam heat exchangers and condensate receivers in Controlling Steam Heaters3.<br />Surge drums are sometimes used for gas. The abrupt flow variations of a Pressure Swing Absorption (PSA) unit, for example, often need to be smoothed out before the tail gas can be introduced into a down-stream process. In these cases, pressure takes the role that level has in a liquid process. That is, a pressure/flow cascade is the appropriate solution.<br />TUNING SURGE TANK CONTROLLERS. Since the exact level of a surge drum is not important, the controller can be tuned very loosely allowing the level to rise and fall in response to any short term imbalances. This exactly serves the purpose of the surge tank; tight tuning defeats it. There is a non-linear control algorithm which specializes in the type of loose control required by surge tanks. One common name is the "gain on error squared" controller. Figure 6-2 shows its characteristic. The controller responds to small errors with a small gain; it responds to large errors with a large gain. This means that in the vicinity of the setpoint, the controller allows the level to drift freely and<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-2<br />the flow to remain almost constant. With luck, the level will average out again before the deviation from setpoint is too great. If the level changes far from the setpoint so that the danger of running out of capacity exists, the controller responds with a strong signal and rapidly brings the level back to near setpoint.<br /><br />Another form of non-linear controller is also available: The notch or gap controller. This algorithm has the gain divided into three segments by two break points. The middle segment, on either side of the setpoint, has a low gain to avoid excessive action while the outer segments have a higher gain for a rapid return. It has the advantage of allowing the user to set the breakpoints and gains below the setpoint differently from those above. Its disadvantage is that it has four tuning constants instead of only the one found in the gain-on-error-squared controller. Some gap controllers have a zero gain in the centre segment. This is totally useless as the controller will never bring the level back to the setpoint. (No gain, no action.) Instead it will tend to use either the upper or lower breakpoint as its effective setpoint and return the level with a high gain. It should be noted that for a controller using a velocity algorithm an abrupt change in gain does not imply an abrupt change in valve position, only a change in the rate of movement. This function is more difficult to implement with controllers using the position algorithm as the controller has to be re-initialized with every gain change.<br />A simple proportional mode controller is sufficient for many surge drum applications. A slow integral may be used to bring the level back to the setpoint during a prolonged change in flow rate, but it should be turned off if cycling results. Do not use the derivative mode! Besides amplifying noise, derivative provides tight control by cancelling out the integrating capacity of the tank and thus defeating its purpose. A tuning rule I have heard of, but have not tested myself is<br />K = ΔF/F * ΔL/L<br />Where K = controller proportional gain<br />ΔF/F = the proportion of flow variations in the uncontrolled flow<br />ΔL/L = the proportion of level available for surge. This is the distance between the level setpoint and the nearest alarm.<br />This formula attempts to put the loosest level control consistent with keeping the level away from the alarms. There is a catch, however: It is necessary to predict the amount of flow variation to be expected in the future. Of course it is also necessary to do this to a certain extent when the vessel is sized.<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-3<br />SUCTION SCRUBBERS. A compressor suction scrubber is an example of a vessel whose purpose is to separate, collect, and dump relatively small quantities of liquid from a gas stream. The following conditions generally apply:<br />• Precise level control is of no value.<br />• The liquid flows to some form of drain.<br />• Smoothness of liquid flow is of no value.<br />• The average liquid flow is quite small.<br />• The pressure differential across the valve is high.<br />• Relatively large slugs of liquid occur occasionally.<br />The last three conditions would result in a valve that is usually operating near its seat with a high ΔP. It would experience severe erosion resulting in a short, unhappy life. The solution is to control the valve in on/off or "snap acting" mode. There are several ways to accomplish this. The simplest is to tune the controller to a very high gain. This would cause the valve to spend almost all its time in the full open or closed position. Unfortunately the high-gain controller would also try to maintain accurate level control by rapidly switching the valve between these extreme positions. Any saving in seat erosion would be cancelled by a high rate of stem and packing wear. The same response can be achieved by using a simple level switch connected to the control valve via a solenoid. (Pneumatic level switches tubed directly to the valve actuator diaphragm are also available.) A level switch can be viewed as a controller with an extremely narrow proportional band (0%!) and consequently an extremely high gain (100% / 0% = ∞!).<br />Selecting a switch with a broad deadband results in a great improvement. The valve now remains fully open until a significant reduction in level is achieved. It then remains fully closed until the level substantially rises. With this arrangement it is possible for the valve to have both long life and peak capacity. Recent experience indicates that transmitters are more reliable instruments than switches and also demand less maintenance4. If a transmitter is used the deadband function is accomplished through logic in the control system. This would have the added advantage of allowing the operator access to the high and low setpoints. In some ways the suction scrubber acts as the exact opposite of a surge drum -- it collects slow dribbles of flow and releases them as intermittent surges.<br />Sometimes there is a third option -- specialized liquid dump valves. These behave somewhat like steam traps in their ability to pop open in the presence of liquid and snap shut in the presence of vapour. Since they are not general purpose instruments, it is best to use them only when there is an opportunity to test their performance; the vendor should be consulted. These devices might be very cost effective in packaged equipment such as on the discharge receiver of an instrument air compressor.<br />STEAM DRUMS. The purpose of a boiler steam drum is to provide space in which the water and steam may disengage. Since the drum serves at high pressures and temperatures, perhaps up to 3600 psi and 1000ºF (25 MPa and 540ºC), it is expensive to manufacture and there is considerable economic incentive to keep it as small as possible. The techniques of boiler feed water (BFW) control can be applied whenever extremely tight level control is a requirement.<br />The level of the feedwater in the steam drum must be kept above the bottom of the drum or a<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-4<br />catastrophic explosion may result. It must also be kept below the steam outlet or liquid water will be carried over. Water droplets will damage superheater tubes, turbine blades, and other equipment. The diameter of the steam drum, and hence its cost, is determined largely by the ability of the control system to keep the water level within bounds.<br /><br />LTLVRiser Tubes~~~~BFW In~~~Steam Drum1Steam Out1V1VLIC<br />Fig. 6-3. Single-Element BFW Control<br />Thus level control of a steam drum has exactly the opposite purpose of that of a surge drum: The water level must be kept within an extremely narrow band and tight control is of essence. It is a simple matter to maintain tight level control... use both the proportional and integral modes and turn up the gain! Figure 6-3, Single-Element BFW Control, shows this very simple arrangement. As always, there are problems. Firstly, high gain means extremely rapid swings in flow rate. The BFW pumps suffer under that type of abuse. There is a second problem, peculiar to boilers, called "swell". Swell is the phenomenon in which a rise in steam demand causes a drop in pressure. This in turn results in a rapid boilup within the tubes which causes the water level to rise. Paradoxically, an increased steam removal rate causes a rise in level due to the swelling of the steam bubbles. The level controller responds by reducing BFW flow at the very moment it is needed most. The swelling water soon collapses as the steam rises to the surface. Now the controller reverses its response and adds a large amount of essentially cold BFW into the system. This causes the water temperature to fall. The cooler water shrinks, lowering the level further. The use of single-element control is not very highly recommended for boilers!<br /><br />http://www.drLTLVRiser Tubes~~~~~~~Steam Drum1LYBFW In1VV1TTSteam OutFT1VLICV++2VVFY2VPT22<br />Controlling Vessels and Tanks Fig. 6-4. Two-Element BFW Control<br />The disturbance to the level is caused by a change in steam withdrawal rate. Since this is a measurable quantity, feed forward can be applied to the level controller output. Figure 6-4 shows how this is accomplished. The compensated steam flow is added to the output of the level controller. Thus a rise in steam withdrawal and the swelling of the water is accompanied simultaneously with a surge of cold<br /> iedger.ca/ce6_v&t/CE6_V&T.html Page 6-5<br />BFW. Ideally the two cancel out exactly and the controller sees no change in level at all. They will not cancel out exactly for two reasons: Firstly, there is no reason why they should. One effect or the other will predominate. They won't even be simultaneous. Secondly, the BFW flow can only equal the steam withdrawal if the range of the valve is exactly equal to the range of the compensated steam flow. Since these two functions must be exactly equal over the entire operating range, it means that the valve must be perfectly linear and that its ΔP is absolutely constant. Not likely! So the level controller still has some work to do to keep the accumulated error at zero.<br />The rather farcical suggestion in the previous section, piping the inlet to outlet and bypassing the vessel, suggests a solution to the valve linearity problem: Use the measurement of the steam leaving the boiler as the setpoint to a BFW flow control loop. The level should remain constant once the shrinking and swelling have reached the new equilibrium. This simplistic solution overlooks a basic principle of process control: No two measured quantities are ever identical. In other words, the two flows will never be the same and the level will rise or fall at a rate proportional to the difference. Since level is a measure of the accumulated difference, a level controller is used to correct the BFW flow. What I have just described is the classic three-element boiler level control arrangement as shown in Figure 6-5.<br />The diagram also illustrates a few other features. Compensation has been applied to account for the effect of pressure on the steam density and its effect on the level transmitter. BFW flow is sometimes temperature compensated since it is most probably preheated and its temperature may vary. For a temperature change from 0ºC to 300ºC (32ºF to 572ºF) the specific gravity changes from 1.000 to 0.712 and a measurement error of 15% will result.<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-6<br />This detailed exposition of boiler level control is presented only to provide an example of how extremely tight level control can be accomplished when necessary. Boiler control is a rather broad subject and many articles and textbooks have already been published concerning it.<br />CONTROLLING LIQUID INTERFACES. It is generally assumed that level control refers to the control of a gas/liquid or vapour/liquid interface. It ain't necessarily so. An interface can occur between any two immiscible fluids. Since all gases are miscible with each other in all proportions, interface level control is always taken to mean the interface between two liquids such as oil and water.<br /><br />Figure 6-6 shows an example of a boot on a crude oil separator. This vessel serves three purposes: It is a gas/oil separator, a feed surge drum and a water separator. A real vessel in this service probably contains inlet baffles and demister pads. Each of the three phases must be individually controlled. But it is possible for the gas phase to discharge to an externally pressure controlled system or even to atmosphere. (Possible yes, acceptable no.) The key to understanding the function of any separator is to think in terms of a constant inventory of each component. To repeat: each component must be controlled individually. The amount of gas flowing in must be balanced by gas flowing out. Changing pressure is a measure of the gas imbalance, therefore pressure control is the appropriate way of controlling the gas outlet. Similarly, oil level is an indication of oil imbalance and water level indicates water imbalance. None of the three streams may be controlled on flow, although a level / flow cascade is often used to smooth out flow variations to the downstream equipment. Pressure / flow cascade is unlikely to be used unless the volume of the vessel is large enough to serve as a gas surge drum. Level / flow cascade on the water is unlikely since the water probably drains to a collection system that itself serves as a surge drum to a number of separators.<br />Sometimes the ratio of water to oil is too great for a boot separator. In such cases a weir may be used to divide the vessel as shown in Figure 6-7.<br />Certain precautions must be taken to make sure that the level transmitter actually gives a true indication of the interface. There are basically two varieties of level indicating devices: The first measures the distance of an actual interface from some fixed point. Ultrasonic and radar devices belong to this group. These would be ideal for the purpose except that they are often not suited for installation in pressurized vessels. Furthermore they have difficulty "seeing" anything other than the<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-7<br />very top interface. Even surface foam and condensation on the instrument “window” can confuse them.<br /><br />The second, and more traditional, variety integrates some particular property, such as density or dielectric constant, over a span. Displacers, differential pressure transmitters, bubbler tubes, nuclear densitometers, capacitance probes, and even gauge glasses all belong to this variety. The key to successful measurement is that the level sensing device must sense only the two fluids bounding the interface. For a gauge glass this means that the lower tap must be in the lower of the two fluids and the upper tap must be in the fluid immediately above it. There may be NO intervening phases.<br />Figure 6-8 shows what happens when a gauge glass is connected to a vessel containing a vapour and two liquid phases. Assume that equal amounts of a liquid with Sg = 1.0, e.g. water, and a liquid with Sg = 0.5, perhaps propane, gradually flow into the vessel. Assume further that the span of the gauge glass is four feet, beginning one foot from the bottom of the vessel.<br /><br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-8<br />As the level of the propane rises, it flows into the glass. As both liquids rise further, water begins to enter the bottom of the glass. This is the state shown in vessel A. Up to this point, the glass shows a true indication of the level of propane in the vessel. Once water enters the glass, the propane is cut off. A constant plug, one foot thick, floats on top of the water. Its level no longer bears any obvious relationship to the actual level in the vessel. This is state shown in vessel B. The only relationship between the vessel and the glass is that the hydrostatic pressure is the same for both at the point where the glass taps into the vessel. A gauge glass is really nothing more than a manometer.<br />Once the level of the propane rises above the upper tap, it flows into the glass and the two interface levels adjust to the same elevation, as shown in vessel C. The gauge will continue to read correctly as long as its lower tap is in the water and the upper tap is in propane. If either fluid is withdrawn so that the upper tap is in the vapour space, the glass will once again read falsely.<br />This same analysis applies to any type of level indication based on density. Remember that a ΔP transmitter only gives a single reading, i.e. differential pressure. Therefore only a single quantity can be inferred. If the instrument is affected by only two fluids, it can yield the correct interface level between the two. If there are more than two distinct phases within the span of the two taps, it will give a reading based on the average densities of all the fluids within its span.<br />Capacitance or nuclear level transmitters will give similar results in multiphase situations, based on the average dielectric or nuclear absorption constants, respectively.<br />So... how can the process controls engineer be assured that the level readings are meaningful if even a gauge glass can't be trusted? Plan "A": Make the entire vessel out of glass. This isn't usually practical so we must fall back upon Plan "B": Every section of a gauge glass must have separate taps into the vessel so that each pair of taps has no "hidden" phase floating in between. Either that, or accept the fact that until the interface reaches its "normal" range, gauge glasses and transmitters will read falsely.<br />SLUG CATCHERS. Slug catchers are a special instance of three-phase separators frequently found in oilfield service. In addition to the usual separation functions, they are required to serve as surge tanks that can smooth out intermittent flow and also handle occasional very large surges in inlet flow. This is done by having two controllers connected to the oil-side transmitter. The oil overflow controller has its setpoint slightly below the top of the weir. In this manner, any surges can be accommodated by the large volume above the weir. This is in fact a non-linear, adaptive gain transmitter since transmitter gain = Δ output / Δ volume.<br />The inlet controller responds to the same level but has its setpoint just below the top of the vessel. It takes action only when the level rises to its set-point. This would happen if an unusually large slug of liquid arrived or if an upset in the downstream process caused the system to back up into the slug catcher. The facility would then be operating under "capacity control". Facilities lacking the capacity control feature are likely to experience a high level shutdown precisely when they are attempting to operate at maximum throughput. Not a very desirable occurrence.<br />It is common for level controllers to be tuned using both the proportional and integral modes. Since the inlet controller is normally functioning with the level well below its setpoint, reset windup will<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-9<br />occur. This is a phenomena in which the controller attempts to raise the level to the setpoint by forcing an ever higher signal to the valve. This does not work, of course, since the valve is already wide open. If a sudden surge arrives that abruptly raises the level to the setpoint and beyond, the controller will be slow to close the valve since it has "wound up" in the opposite direction. Some form of anti-reset windup is required to prevent an unwarranted high level shutdown under these circumstances. It is probably a bad idea to use an equal percent valve in this application since it, also, is likely to respond slowly to a sudden demand.<br /><br />It is possible to control the outlet and inlet valves with a single, split-range controller. This method accomplishes the required function of preventing high level shutdowns but has a serious disadvantage. If the setpoint of the combined inlet/outlet controller is set below the top of the weir, it will not take full advantage of the surge capacity of the vessel since the inlet will begin to close well before the top of the vessel is reached. If the setpoint is above the weir, it defeats its purpose by allowing mixed feed to flow directly to the oil outlet before it has time to separate. Thus a split-range controller will sacrifice either separation quality or surge capacity.<br />PRESSURIZATION SYSTEMS. A tank, vessel, or drum may require a pressurization system for any of a variety of reasons:<br />• The surface of the liquid in a reflux drum consists of a liquid at equilibrium with its vapour. There may not be sufficient gravity head to provide the net-positive-suction-head required to operate the reflux pump without cavitation. Raising the vessel high in the air above the pump is one way of providing this. Unfortunately the condenser providing the liquid, drains by gravity so it must be raised even higher. The entire arrangement can become extremely expensive. An-other method is to use a canned pump which is sunk deep into the ground. This can also get<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-10<br />pricey. A blanket gas pad may be a relatively inexpensive way of providing the necessary pressure.<br />• The liquid in a storage tank is subject to oxidation, e.g. the surge tank of a glycol-based heat exchange system. A blanket of fuel gas will prevent the tank from breathing air as it cycles from empty to full and back again.<br />• The liquid in a storage tank forms an explosive mixture with air. (A rather extreme form of oxidation!) A continuous gas purge may be required to prevent this.<br />• The storage tank vents to a flare or other vapour collection system. A gas supply must be provided to make up any volume withdrawn when the withdrawal rate exceeds the fill rate. In other words, the pressurization system serves as a vacuum breaker.<br />A simple way of providing pressurization is to have a regulator connected to a source of pad gas and a second, back pressure regulator, connected to the vent. Care must be taken to set the back pressure regulator setpoint slightly higher than that of the inlet regulator. If there is no gap between the two settings, the pad gas will blow straight through to the vent. Remember that setting them to the "same" pressure is meaningless.<br /><br />Often it is necessary to install a complete control loop including a pressure transmitter, a controller, and two valves. This has the advantage of allowing the panel operator to monitor and adjust a single setpoint. It also allows over- or under-pressure alarms to be easily provided. Figure 6-10 shows how the complete pressure control loop is arranged. For the most part it is pretty simple but there are two things to watch for: Firstly, there must be a gap between the action of the two valves. That is the reason for the split range values not meeting at 50%. Secondly, the failure mode of the valves must be taken into account. Since the two valves have the opposite effect, they must have opposite failure modes if they are to be operated by the same control signal. A DCS allows the output of the controller to drive two separate output modules, each characterized in its own way. This means that it is possible for the first 45% of the controller output to produce a 100 to 0% signal for the fill valve, and the last 45% of the output to produce a 0 to 100% signal for the vent valve. In this way both failure modes are accommodated and overlap of valve openings is impossible. The gap in the middle does not cause a problem for the controller. Integral windup will move the output quickly through the gap whenever there is a deviation from the setpoint. The reader should note that the split range control described in this paragraph is not at all the same as that described in the section on Slug Catchers.<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-11<br />It is possible to achieve the same effect by using a specialized, three-way valve that provides a gap in the middle. Most three-way valves are designed to have full overlap as they are intended for use in diverging/converging service. (If anyone knows of a centre-gap, non-overlapping valve, let me know.)<br /><br />A number of vendors sell specialized gas blanketing systems capable of self-contained action. They consist of regulators with the very large diaphragms required to drive valves with pressures as low as 0.5" WC (125 Pa, 0.3 oz/in2). Such systems are especially useful now that ever more stringent regulations concerning the emission of volatile organic compounds (VOCs) are being enforced. Figure 6-11 shows one typical arrangement.<br />Many factors enter into the correct specification of the setpoints and sizes for the various regulator and relief valves. These include:<br />• The maximum allowable pressure of the tank.<br />• The maximum allowable vacuum of the tank.<br />• The vapour pressure of the stored liquid.<br />• Inbreathing rate dependent on pump-out rate.<br />• Outbreathing rate dependent on pump-in rate.<br />• Vapour thermal expansion and contraction rate.<br />• Tank surface area and insulation.<br />Table 6-1 provides setpoints applied in a specific case. It must be remembered that actual values differ widely. API 2000, Venting Atmospheric and Low-Pressure Storage Tanks5 and tank vendors provide much information, however it may be advisable to consult a specialist in the field.<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-12<br />oz/in2 "WC kPa<br />Maximum Allowable Pressure 4.0 6.9 1.7<br />Manway Setting 3.5 6.1 1.5<br />Relief Valve Pressure Setting 3.0 5.2 1.3<br />Vent Regulator Setting 2.0 3.5 0.9<br />Fill Regulator Setting 0.5 0.9 0.2<br />Relief Valve Vacuum Setting -.05 -.09 -.02<br />Maximum Allowable Vacuum -1.0 -1.7 -0.4<br /><br />Table 6-1. Typical Tank Blanket Pressure Settings<br />A brief sermon on tagging: According to ISA 5.1, Instrumentation Symbols and Identification6, all forms of relief valves including pressure, vacuum, spring- or weight-loaded, with or without a pilot are tagged "PSV". Common abbreviations such as "PVSV", "PVRV" or "PRV" have absolutely no official status and therefore are not acceptable as tags on P&IDs.<br />LEVEL MEASUREMENT. Level measurement is deceptively easy, yet it seems that more time is spent specifying level instruments than any other. The reason is that the correct installation of level instrument is an interdisciplinary effort involving Process, who set the basic functional requirements; Mechanical, who have various constraints such distance of taps from seams; Piping, who have accessibility and orientation requirements; and Instrumentation, who must select from a finite catalogue of available instruments.<br />Actually this task has become considerably easier in recent years due to the increased use of ΔP transmitters and other instruments such as ultrasonic and radar which do not have a predetermined span. There is no longer any significant penalty in either cost or accuracy if the instrument is specified to cover a broad span. For horizontal vessels the top connection should be vertical at the top of the vessel. The bottom connection should be horizontal a few inches from the bottom. This is necessary to prevent the accumulation of sediment. These connections no longer need to be in the same vertical plane nor do they require the same orientation.<br />Vertical vessels may still require a bit more attention. While a top-to-bottom span would be ideal, there may be trays, packing, or other internals that would cause a differential pressure in response to flow. It is also necessary for the level connections to remain clear of welding seams. This requirement may cause problems if alarms or other setpoints need to be near the bottom or top of the vessel.<br />The design process begins with the basic information on a P&ID in a form similar to that shown in Figure 6-12. A brief outline of the vessel including the bridle, if any, holding a gauge glass and a transmitter are shown. The desired values for the level alarms and the setpoint of the controller are also shown.<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-13<br />The Control Systems engineer must first decide if a ΔP transmitter is the appropriate choice. Let us assume it is. He/she must then try to find an appropriate span for the transmitter. A good rule of thumb is that alarms should not be set any lower than 10% or higher than 90% of the transmitter span. (Shutdown trip settings should not be closer than 5% from either end of span.) Since the two alarms are 42" - 6" = 36" apart, the span should be 36" x 1.25 = 45" thus allowing the alarms to be at 10% and 90% of span. This seems fine, but there is a problem. The first thing to determine is whether the vessel measurements are from the tangent line, from the seams or from some other reference point. In this particular case the vessel title block indicates that measurements are tan-to-tan. Since seams are generally 2" inside the tan lines, the lower tap of the transmitter is ½" above the seam. That is not acceptable. Mechanical considerations often dictate that nozzles may not be welded within 6" of a seam. This means that the lowest transmitter tap cannot be lower than 8" above the bottom tan line. The highest tap cannot be higher then 8" below the top tan line. This implies that the maximum transmitter span on a 48" T/T (tan-to-tan) vessel is 32". Alarms at 10% and 90% must be placed at 11.2" and 36.8". At this point, the Instrument Engineer becomes a broker between Process and Mechanical to help them find a compromise. Alarms at 11" and 37" are agreed upon. Don't forget to transfer this new information back to the P&ID!<br /><br />LTVVV24"V-21624" ID x 48" T/TV-216LAL6"NLLLAH42"LGLAHLALLIC<br />Fig. 6-12. Level Setpoints<br />It is a great convenience to the maintenance staff if the span of the transmitter is exactly equal to the span of the gauge glass. This is not always possible with displacers since both the gauge glasses and the transmitters come in fixed spans. However, it can easily be done for ΔP transmitters. The centre line of the sensing taps must be located at the tops and bottoms of the visible glass. Unfortunately, the associated valves bring the centre line of the gauge glass tap 4½" below the bottom of the glass. Fortunately, in extreme cases, it is possible to place the lower gauge glass tap below the lower bridle tap. There can be no meaningful readings below the lower bridle tap of course, since the bottom of the glass can never drain back into the vessel. As long as the glass itself does not go below the lower tap, it's OK. Since gauge glasses come in fixed lengths, it may not be possible for the upper tap of the transmitter to match the top of the visible glass. Remember that transmitter calibration will be more difficult if the upper tap does not fall within the range of the visible glass.<br />Occasionally it is necessary to connect either the top or the bottom taps to interconnecting pipe instead of to the vessel itself. If the taps are attached to inlet or outlet lines, the level signal will be affected by flow rate. This effect can be seen in coffee percolators: The level in the gauge glass bobs up and down as coffee is drawn into a cup.<br />SEALS. Diaphragm seals have become a very popular accessory to ΔP-based level transmitters. A very thin metal diaphragm isolates the transmitter from the process. The space between the<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-14<br />diaphragm and the sensor itself is filled with a fluid such as silicone. The pressure changes are communicated through the diaphragm to the transmitter via an armoured capillary tube. The volume change between minimum and maximum pressure is extremely small in a modern transmitter; the amount of flex in the diaphragm is correspondingly small. The net effect of this is that the introduction of a diaphragm into a measurement system introduces an error of only several centimetres or less. This is seldom significant in level applications. A second effect is that only an extremely small amount of liquid movement actually occurs in the capillary tubes. This, together with modern low temperature fill fluids, means that the instrument response does not slow down too much on cold days. Figure 6-13 is an example from one vendor's catalogue.<br />Fig. 6-13. A Typical Differential Pressure Transmitter with Diaphragm Seals<br />Seals should be considered whenever one or more of the following conditions apply:<br />• Dirty service - Whenever the process fluid is liable to plug the impulse lines, a diaphragm seal may be installed. It should be isolated from the vessel by a full-ported valve, NPS 2 or 3. Note that two NPS ½ taps are provided on the diaphragm housing for calibration and flushing connections. Seals are especially useful in sanitary service where all hardware in contact with process fluid must frequently be thoroughly washed. It is a good idea to use seals and capillaries of equal length on both the upper and the lower leg in order to maintain a balanced response to errors.<br />• Corrosive service -- Diaphragm seals made of corrosion resistant materials originated in corrosive service where they were referred to as 'chemical seals'. While the use of full-ported<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-15<br />connections is not required in corrosive service, it is a good practice to maintain even if it might look strange to have 'such a big valve' for 'only' an instrument.<br />• Freeze protection -- Diaphragm seals may eliminate the problem of freezing impulse lines. However, in extremely cold weather it may still be necessary to heat trace the capillaries to prevent measurement response from being excessively slow. Self-limiting electrical heat trace is the only way to go! Any heat trace system involving a thermostat will introduce spikes into the measurement system as the heat is switched on and off.<br />• Uncertain phase -- This is the most frequent of all seal justifications. A warm vapour in equilibrium with its liquid will undergo condensation in the upper impulse line. Cold equilibrium liquid may experience boiling in the lower impulse line. Thus the measurement will slowly drift as the tube fills. Depending upon service and ambient temperatures, condensation and boiling may even alternate throughout the day. If this situation exists, the measurement becomes worthless. The traditional solution is to fill the upper line with a non-volatile, process compatible fluid. Depending on process and ambient conditions this might be water, glycol, oil or something else. The use of fill fluids introduces maintenance problems because any attempt to 'null' the transmitter by opening the equalization valve will drain the upper fluid into the process. It can only be replaced by climbing to the top of the vessel and filling the tube again. Bubbles are also a source of error. Seals provide a captive fill fluid that cannot be lost, does not form bubbles and cannot contaminate the process. (Did I say foolproof?)<br />UNDERGROUND TANKS. A special requirement concerns underground (UG) tanks. Modern steel UG tanks have a double wall construction. Requirements are outlined in CAN/ULC-S603, Standard for Steel Underground Tanks for Flammable and Combustible Liquids7. The two walls of the tank are approximately an inch (2 cm) apart. A vacuum of 51 kPa (7.5 psi) is drawn on the interstitial space so that the two surfaces are, in many places, actually in contact with each other. A vacuum gauge is connected to the interstice. It must read at least 42 kPa (6.1 psi) of vacuum before the tank may installed. If the reading is ever less than 34 kPa (4.9 psi) the tank should be removed from service and steps taken to determine the cause of the leak. These values are summarized in Table 6-2, below. If a facility has many UG tanks, it may be desirable to connect the tanks to the central control system by means of vacuum transmitters. Low vacuum alarms can then be configured to alert the operators of any cases of leakage.<br />Interstitial Vacuum psi kPa<br />Required at manufacturing 7.5 51<br />Minimum acceptable for delivery 6.1 42<br />Minimum allowable in service 4.9 34<br /><br />Table 6-2 Interstitial Vacuum Requirements for Underground Tanks<br />VOLUME MEASUREMENT. Most vessel and tank content measurements are made in the form of level. When true volume is required for such purposes as custody transfer, the tank volumes are calculated taking into account all details of their geometry as well as dimensional changes resulting<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-16<br />from the pressure exerted by the density of the liquid. The results of these calculations and calibrations are tabulated by the manufacturer in a form known as “strapping tables”.<br />True volume measurement is seldom relevant for control purposes since setpoints for controllers and alarms are usually related to specific geometric features of the vessels. The level must often be kept below the vapour outlet or a weir. A frequent requirement is that a specific head be maintained to prevent pump cavitation. Sometimes the requirement is simply to maintain the level near midpoint in order to provide surge capacity. None of these applications benefit from true volume compensation. Figure 6-14, Volume vs. Height for Cylinders and Spheres, provides the correct mathematical relationship between level and volume for these two vessel styles if true volume measurement is actually required. It can be seen that between 10% and 90% little is gained by applying the rather complex calculations required for volume control.<br /><br />0% Actual Volume 100%0% Transmitter Reading 100%0% Actual Volume 100%CylinderSphereRR-hohLh0% Transmitter Reading 100%RR-hhR<br />Volume = (R2L/2)(2θ - sin 2θ) Volume = -(π/3)h2 (3R - h)<br />Where h = height of liquid in vessel<br />R = radius of vessel<br />L = length of cylinder<br />θ is radians and cos θ = (R-h)/R<br />Note: The volume contained by elliptical vessel heads is ½ that of a sphere of equal radius.<br />Fig. 6-14. Volume vs. Height for Cylinders and Spheres<br />SAFETY. Vessels and tanks are probably the most hazardous pieces of equipment in any plant. Duguid’s database20 shows that 22% of all safety incidents are related to storage and blending. This<br /> Controlling Vessels and Tanks http://www.driedger.ca/ce6_v&t/CE6_V&T.html Page 6-17<br />may seem a little surprising until one considers that they store energy as well as material. For example:<br />• A vessel holding a compressed gas can cause a tremendous explosion if it ruptures. That is why "hydrotesting" with air or nitrogen is far more dangerous than with water.<br /><br />Torrent Kills Nine<br />The Associated Press<br />MELILLA, Spain November 19, 1997<br />A water tank burst and sent a river of water surging through a busy market area in a Spanish enclave on the northwestern African coast, a city official said Tuesday.<br />Nine people, including two children, died and 30 were injured.<br />The accident unleashed 24,600 litres of water which dragged cars and market talls through Melilla's streets.<br />s<br />• Storage tanks can hold a considerable amount of gravitational energy. The most notorious example of this energy being released is the infamous "Boston Molasses Disaster" which occurred January 15, 1919. A tank located at the top of a hill ruptured and released two million gallons of molasses down a narrow street. Twenty-one people were killed and 150 were injured.<br />• The contents of the tank or vessel can be flammable. While a line rupture external to the tank may be the cause of a fire, it is the reservoir of flammable fluid inside a tank that turns a minor fire into a major one. API RP 750, Management of Process Hazards, specifically addresses this point, however, it does not offer much in the way of solutions.<br />• The contents of a tank can be lethal. The February 1984 release of methyl isocyanate in Bhopal, India was the worst non-nuclear industrial accident in human history. Over 2000 people were killed by the toxic vapour.<br />The single, most comprehensive guide to the design of vessels is the ASME (American Society of Mechanical Engineers) Boiler and Pressure Vessel Code8. This rather large document deals with all aspects of vessel design, construction and operation. Section VIII, Parts UG-125 to 136, in particular, deal with the requirements for pressure relief.<br />The pressure relieving requirements for non-pressure vessels, i.e. tanks, are covered in detail in API Standard 2000, Venting Atmospheric and Low-Pressure Tanks5.<br />Most safety related design practices applying to vessels and tanks are beyond the scope of the instrumentation and controls engineer; relief valves are an exception. Their correct sizing and selection is too broad a subject to be covered in this article especially since there is already a lot of material in print concerning them. Items 9 through 14 of the references below deal extensively with this subject. The earlier section, Pressurization Systems, gives a typical example of pressure protection for an atmospheric tank.<br />REFERENCESSumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-88082877197652944042008-11-22T06:15:00.001-08:002008-12-23T01:17:25.195-08:00Manufacturing Process EncyclopaediaWater jet cutting<br />Other names / variants: Hydrodynamic machining, Abrasive jet cutting<br /><br />Overview<br />• Jet cutting (or hydrodynamic machining) has been widely used in the food industry for a long time, but more recently it being taken up by general engineering manufacturers.<br />• The basic process is very simple – a concentrated jet of fluid at almost supersonic velocity is directed at the workpiece which literally ‘blasts’ the material out of the cut.<br />• In the food industry, oil is used which provides a hygienic means of cutting.<br />• In metal cutting, fine abrasives in water are used – steel up to 100mm thick can be cut<br />this way.<br />• All though the process is quite slow, sheets can often be stacked up and several cut at once.<br />• The primary advantage for metal cutting is that the process generates very little heat, so the material is not affected in any way.<br /><br />Process details<br /><br />Abrasive jet machining<br />An abrasive jet uses water that is pressurized up to 40,000 pounds per square inch (psi) and then forced through a small sapphire orifice at 2500 feet per second, or about two and half times the speed of sound. Abrasive (often garnet) is then pulled into this high-speed stream of water and mixed with the water in a long ceramic mixing tube. A stream of abrasive laden water moving at 1000 feet per second exits the ceramic tube. This jet of water and abrasive is then directed at the material to be machined. The jet drags the abrasive through the material in a curved path and the resulting centrifugal forces on the<br />particles press them against the work piece. The cutting action is a grinding process where the forces and motions are provided by water, rather than a solid grinding wheel.<br /><br />Materials and shapes<br />• Abrasive waterjets can machine a wide range of thicknesses and materials, including metals, plastics, glass, and ceramics.<br />• Materials cut by the abrasive jet have a smooth, satin-like cut edge, similar to a fine sandblasted finish.<br />• Little heat in machining process.<br /><br />Vacuum forming<br />Other names / variants: Thermoforming<br /><br />Overview<br />Almost the opposite of blow moulding - with sucking instead of blowing! As a result, the two processes are useful for different types of shape, although both can only produce parts with thin walls. This process is more properly called thermoforming and relies on the sudden drop in strength and stiffness of thermoplastics above a certain temperature.<br /><br />Materials and shapes<br />Only suitable for thermoplastics and some polymer foams. Shapes should have constant section thickness and not 'curve-back' on themselves. Parts cannot have holes or openings. Surface texture good, but fine detail in mould cannot be copied. Suction holes in mould need to be small to avoid leaving a mark on the product. Near-net-shape, but often leaves some waste material that needs trimming (and is difficult to recycle).<br /><br />Economics<br />Cycle time is limited by heating and cooling of the sheet. Normally cycle times of 5+ units a minute can be achieved. Production rate can be increased by multi-part moulds, although extra trimming will be required. Manual equipment is cheap enough to use in a school workshop. Fully automated equipment can cost over £250,000. Moulds are usually aluminium (although wood can be used for small-scale production) and so relatively inexpensive. Manual systems viable from 1 - 1000 parts. With fully automated systems, only becomes economically viable for batches over 10,000.<br /><br />Typical products<br />Advertising signs, bath panels, washing-up bowls, packaging.<br />___________________________________________________________________________________<br />Turning<br />Overview<br />Turning is unusual amongst the machining processes in that it is usually the workpiece that moves, whilst the cutting tool remains stationary. Lathes in metalwork shops usually have single point cutting tools. Lathes in woodwork shops often have tools with simple shapes to make turning of complicated shapes more simple. Lathes in industrial woodworking have large, intricate cutting tools, capable of shaping a complicated piece with only a few inserts of the tool.<br /><br />Materials and shapes<br />• Woods and metals are the most commonly turned materials, although difficulties arise with the high-strength metals.<br />• It is possible, but unusual, to turn polymers. Rigid polymer foams are sometimes turned when producing models for prototypes.<br />• Turning is usually used to produce parts with radial symmetry (i.e. based on a cylinder).<br />• It is possible to produce other shapes, e.g. a helix or screw thread, by turning the part slowly and moving the cutting head at a constant rate.<br />• Wood is the most commonly turned material, as it is easy to produce a wide variety of aesthetic<br />shapes.<br />Economics<br />• The use of dedicated lathes for metal turning is rare on an industrial scale, except for<br />prototyping.<br />• Where metal turning is required industrially, it is usually done as part of the function of a<br />machining centre.<br />• Wood turning for mass production uses dedicated tooling to dramatically increase production<br />rates and hence reduce costs.<br />Typical products<br />• Chair legs<br />• bowls<br />• candlesticks<br />• large threaded shafts<br />___________________________________________________________________________________<br />Transformation hardening<br />Other names / variants: Laser hardening, Induction hardening, Flame hardening<br />Overview<br />Transformation hardening is often used in addition to carburising or nitriding, and is primarily used to<br />improve the mechanical properties of the surfaces of steel components. There are many ways to<br />"transform" the surface microstructure, but all of them involve heating of the surface followed by a<br />rapid quench (either in oil or water, or by a "self-quench" because the bulk of the component will still<br />be cold).<br />• Flame hardening uses a flame gun to provide the heating. It is inexpensive and flexible;<br />however it is quite slow, difficult to control accurately and not easily automated. Only external<br />surfaces can be treated.<br />• Induction hardening works by placing the component in a high-frequency magnetic field. This<br />"induces" a current in the surface and so heats it rapidly. It can be used to uniformly treat large<br />components such as the rolls for a rolling mill. Although this process is expensive and requires<br />some dedicated tooling, it is easily automated and can be applied accurately – e.g. to just the<br />teeth on a gear cog.<br />• Laser hardening works by focusing a laser beam on to the surface to provide very rapid<br />heating. As a result, a self-quench is usually sufficient. The equipment is very expensive and not<br />economic for large surfaces, but automation is straightforward and very precise control can be<br />achieved.<br />___________________________________________________________________________________<br />Surface treatment (generic)<br />Related processes in this database include: Case hardening, Transformation hardening, Surface<br />coating Peening<br />Overview<br />Surface treatment processes apply primarily, but not exclusively to metals. After a component has been<br />formed and finished (e.g. by grinding), it may still not have acceptable surface properties. There are 4<br />main reasons why the surface properties may need altering:<br />1. Improve wear resistance.<br />2. Improve corrosion resistance.<br />3. Improve fatigue resistance.<br />4. Change the aesthetic appearance.<br />There are various ways these aims can be achieved:<br />• Coating the surface in a new material - e.g. painting, electroplating<br />• Altering the surface chemistry/microstructure – e.g. carburising, transformation hardening<br />• Changing the mechanical properties of the surface – e.g. shot peening, planishing.<br />___________________________________________________________________________________<br />Surface coating (generic)<br />Other names / variants: Chemical vapour deposition (CVD), Physical vapour deposition (PVD),<br />Painting, Varnishing, Electroplating<br />Overview<br />By applying a surface coat of a different material, dramatic changes in the surface properties are<br />possible. Normally the materials used for the coats are too expensive, or have the wrong bulk properties<br />to use for the whole components. There are several ways to coat the surface of a component:<br />• Painting / varnishing. Commonly used to provide corrosion resistance for woods, but also<br />widely used for metals. Relatively inexpensive and flexible.<br />• Electroplating is a relatively inexpensive way of providing a surface coat, although it relies on<br />the component being a good conductor and only certain coats are possible.<br />• Physical vapour deposition (PVD) or sputtering works by "shooting" a fine spray of droplets<br />at the component. It is mainly used for metals and ceramics. Although very expensive, it can<br />provide excellent surface properties for high-performance drill bits etc.<br />• Chemical vapour deposition (CVD) is similar to PVD, but the surface is formed by a chemical<br />reaction with a special gas rather than using a spray.<br />___________________________________________________________________________________<br />Soldering and brazing<br />Overview<br />Soldering and brazing differ from welding because only the filler melts, not the materials that are<br />joined. Soldering differs from brazing by the melting temperature of the filler alloy - this is usually<br />below 450oC for soldering and above 450oC for brazing. Soldering using lead-tin alloys was the first<br />hot joining process, used as far back as 4000BC.<br />Materials and shapes<br />Brazing is usually used for joining metals, and especially where the parts are not of the same material.<br />Most geometries are possible; however, good join alignment is essential to achieving a strong joint.<br />Mechanical cleaning or the use of flux is needed to give good joint strength. The strength of the joint is<br />also dependent on good design. Because of the low melting point of the filler, soldered joints have<br />limited use at high temperatures. Also, the joints are usually not strong and therefore not used in loadbearing<br />situations. Soldering aluminium and stainless steel is difficult because of their strong oxide<br />layers.<br />Economics<br />Equipment is generally low cost, except where automation is used. The need for good joint alignment<br />usually means fixtures are required, adding to the cost. Wave soldering is the most economic means of<br />soldering large batches of printed circuit boards.<br />Typical products<br />Plumbing, electrical circuits<br />Sintering and HIPing<br />Overview<br />There are 2 main types of sintering: with pressure (hot pressing or pressure sintering) and without<br />pressure (pressureless sintering). A variant used for 3D shapes is called hot isostatic pressing (HIPing)<br />Much of the research in powder processing is to obtain good quality powder, as this helps to achieve a<br />good quality component.<br />Materials and shapes<br />Mostly used for small (<2kg) components. Dominant method of producing ceramic components. For<br />non-HIPing, sides must be parallel to allow ejection of part. HIPing can work with complex 3D shapes.<br />Very good dimensional accuracy (near net-shape process) with 100% material utilisation.<br />Economics<br />The machinery is expensive, and can cost well over £100,000 for HIPing. The dies are dedicated,<br />expensive (£5,000+) and need to be replaced after about ten thousand uses. They can take several<br />weeks to manufacture, so prototype testing is slow. The production rate is dominated by the sintering<br />stage and is therefore quite slow (2-20 per hour). Because there is little competition, can be economic<br />for small batches (1,000+) - although still not cheap!<br />Typical products<br />cutting tool tips, spark plugs, electrical insulators<br />___________________________________________________________________________________<br />Sheet forming<br />Overview<br />Sheet metal forming (also called pressworking) is among the most important metalworking processes.<br />It is used in the manufacture of a wide range products as there are many different forming operations<br />including blanking, drawing, pressing and bending. Sheet metal is produced by rolling and is generally<br />coiled prior to forming. Parts made this way and subsequently mechanically fastened are said to be<br />fabricated.<br />Materials and shapes<br />Sheets are usually less than 6 mm thick. Dominant material used is mild steel. Blanking (shearing) is<br />used to cut parts for subsequent processing, sheet is shaped with bending (1-D) and drawing (2-D),<br />pressing contains elements of all three. Surface finish is usually good, but this is dependent on good die<br />design and quality. A wide variety of shapes can be made, but die design must account for the elastic<br />'springback' of the sheet after forming. Some scrap is always produced and cannot be directly recycled.<br />Economics<br />Primarily used when near-net-shape processes are impractical in terms of time or materials e.g. for car<br />body panels. Simple manual equipment can cost only a few thousand pounds, but is only used for<br />prototyping and small batches as the production rates are low. Automated tooling (which can be<br />expensive) is usually dedicated to individual components, so is normally only used for long production<br />runs in order to be cost-effective. Production rates with automated equipment can be very high (drinks<br />cans can be produced at almost a 1000 a minute).<br />Typical products<br />Cans, washing machine cases, car body panels, kitchen utensils, hubcaps, metal desks.<br />___________________________________________________________________________________<br />Sand casting<br />Other names / variants: green sand casting<br />Overview<br />• Sand casting is the oldest form of casting and has been used for millennia.<br />• It is still widely used today and in the US alone about 15,000,000 tonnes of metal are cast every<br />year.<br />• Although almost any sand can be used, a mixture of synthetic sand, clay and water, called green<br />sand, is preferred by most foundries.<br />Materials and shapes<br />• Most metals can be cast, the limit is the melting temperature - the higher it is, the greater the<br />cost.<br />• There is almost no limit to the size of a sand casting - casings over 5m wide are routinely made<br />(e.g. ship propellers).<br />• Most shapes can be made, but the surface often has a characteristic rough finish which may<br />need machining.<br />• Removing the extra material left from risers/gates etc. can also greatly add to the cost of the<br />finished product.<br />• Porosity can be a problem leaving parts that are prone to cracking.<br />Economics<br />• The basic equipment cost is low - from £500 to £3,000; automation and higher temperature<br />furnaces can increase this a lot. Dies can be cheap, but take some time to make.<br />• The limit on the production rate is usually the cooling. Small parts can be produced at several an<br />hour - large parts can take hours or even days to cool fully.<br />• The labour intensive nature of the process mean it is usually only economic for small batches,<br />although dedicated automation can increase this to 10,000+.<br />Typical products<br />• Engine blocks<br />• cylinder heads<br />• pump housings<br />• machine tool bases<br />• ship propellers<br />___________________________________________________________________________________<br />Rotational moulding<br />Other names / variants: Rotomolding<br />Overview<br />• Think of a large polymer product, and the chances are it is made by rotational moulding.<br />• This versatile process is surprisingly inexpensive and is used to make a wide range of everyday<br />products.<br />• The main disadvantage is the low production rate which usually limits it to smaller batches.<br />Process details<br />Stage 1: Plastic is introduced to a mould in powder form up to the mass required for the required<br />product.<br />Stage 2: The mould is then closed and passed into an oven chamber. The mould is then heated<br />externally to a temperature typically between 220°C and 400°C and is rotated around both vertical and<br />horizontal axes.<br />Stage 3: As the mould rotates, the inner surface passes through the mass of powder at the bottom of the<br />mould. As the mould heats up, the powder begins to melt and adhere to the inner surface of the mould.<br />The mould continues to rotate in the presence of heat and more plastic melts and builds up to produce<br />an even layer over the surface of the mould. The mould is then withdrawn from the oven whilst still<br />rotating and moved into a cooling chamber.<br />Stage 4: Cool air is directed at the mould and in some cases water jets are used to cool the mould.<br />When the plastic inside the mould has become solid, the mould can be removed from the cooling<br />chamber. The plastic component is then removed from the mould and allowed to finish the cooling<br />process unrestricted by the mould.<br />Materials and shapes<br />• Mainly for thermoplastics (especially polyethylene), but some thermosets can be used.<br />• Used to produce containers and similar hollow products with uniform thin sections.<br />• Tanks up to 4m across can be made this way; wall thicknesses as low as 0.4 mm are possible.<br />• Products are near-net-shape and rarely need further finishing.<br />• Parts do not have to have circular cross-section.<br />• The surface finish depends on the quality of the die surface; it is possible to include surface<br />detail such as logos.<br />• Metal or polymer inserts can be moulded-in during processing.<br />• All material is used in the product so there is no scrap.<br />• Parts with large openings may be produced in pairs in a single mould and separated after<br />removal, or through use of insulation in mould.<br />• The plastic is formed without pressure or centrifugal force and as such has no moulded in<br />stresses.<br />Economics<br />• Cycle time is limited by heat conduction out of the mould, so increases dramatically for larger<br />wall thicknesses.<br />• Thin walled products can be produced at almost 1 a minute, whereas thick walled products<br />might be as few as 3 per hour.<br />• Although the tooling is dedicated, the moulds are usually quite cheap.<br />• Equipment is relatively cheap - between 1 & 10 thousand pounds.<br />• The long cycle times usually limit economic batch sizes to between 500 and 10,000.<br />Typical products<br />• buckets<br />• plastic footballs<br />• dustbins<br />• oil drums<br />• storage tanks<br />• traffic cones<br />___________________________________________________________________________________<br />Rolling<br />Other names / variants: tandem mill, reversing mill<br />Overview<br />Rolling was first used in the 1500s. The basic operation is a bit like flattening dough with a rolling pin.<br />Rolling is unusual in that it is primarily used for making stock items rather than making finished<br />components. Over 90% of worked metals are processed at some point by rolling.<br />Process details<br />Reversing mill<br />• In a reversing mill, a hot ingot in moved back and forth through a set of connected die rolls.<br />• Each roll gets closer the final shape, the last pass will finish the rolled shape.<br />• Reversing mills are used for making thick sections such as slabs or large I-beams. In practice,<br />there do not need to be many separate ‘dies’ (as is shown here) if the operator can move the<br />rolls closer together between passes.<br />Tandem mill<br />• In a tandem mill, a hot slab is passed through a series of flat rolls.<br />• Each of the rolls reduces the thickness slightly, until the desired thickness is reached. If the final<br />sheet is not too thick it can be ‘coiled-up’ while it is still hot.<br />• Tandem mills are mainly used for producing plate and sheet. In practice, 5 or more rolls in<br />series can be used – in which case the material coming out the end can be going very fast!<br />Materials and shapes<br />• For flat sections, ingots over 1m wide are reduced to plates (usually 6mm-300mm), sheet<br />(0.1mm - 6mm) or foil (about 0.008mm).<br />• Shaped sections (such as rails and I beams) up to 300 mm across are made using a series of<br />shaped rolls.<br />• Specialised forms of rolling can be used to make large rings.<br />• Hot rolling has poor dimensional tolerance and leaves a poor surface finish.<br />• Cold rolling can improve these and also improve mechanical properties, but only for small<br />reductions in thickness.<br />Economics<br />• For making stock items, rolling has few competitors.For this reason, it is usually performed by<br />the foundries before passing on to customers for further processing.<br />• For long shaped sections, rolling is the only viable option for larger cross sections - for smaller<br />cross section extrusion may be more economic.<br />• Machines can cost millions of pounds.<br />Typical products<br />I-beams, rails, sheets, plates, foil<br />Rapid prototyping (generic)<br />Other names / variants: Stereo-lithography, Selective laser sintering (SLS)<br />Overview<br />Prototyping is the making of a test component before full manufacture begins. These prototypes<br />provide an important means of assessing a design in a "hands-on" way. Conventionally, prototyping<br />was performed by machining the component from a solid block. With the advent of CAD/CAM and<br />CNC machining, this approach has greatly speeded up – but "rapid" prototyping techniques are even<br />faster. They all work by building-up thin layers in sequence to produce the whole component.<br />Recent trends in rapid prototyping include:<br />• The techniques are now being used with scanning techniques to produce exact replicas of<br />delicate objects such as antique carvings.<br />• Rapid mould development (rapid tooling), where prototypes produced by one of these<br />techniques is coated and can be used directly for injection moulding dies etc.<br />• Making shapes not possible any other way – e.g. custom jewellery, ‘sculptures’ etc.<br />___________________________________________________________________________________<br />Powder metal forming<br />Other names / variants: Sintering, HIPping, Reaction bonding<br />Overview<br />• One of the first uses for powder metal forming was the manufacture of tungsten filaments for<br />light bulbs. Advances in the technology mean even structural parts for aircraft (e.g. landing<br />gear) can be made this way.<br />• Much of the research in powder forming is to obtain good quality powder, as this helps to<br />achieve a good quality component.<br />Variants<br />• Pressureless sintering involves only heat. It can be used for any shape.<br />• Pressure sintering involves heat and axial pressure, but can only be used for 2D components.<br />• HIPping (hot isostatic pressing) is a variant used for 3D shapes; it uses a foil bag and a<br />hydrostatic pressure chamber.<br />• Reaction bonding involves using a binder (so it can be moulded like plasticine) which is later<br />burnt off; it can used for most shapes.<br />Materials and shapes<br />• Possible sizes range from balls in ball point pens up to 25kg.<br />• Mostly used for small (<2kg) complex components that are difficult to make from solid stock or<br />where uniform properties are desired.<br />• All metals can be processed this way, though extra care is required for some which burn or<br />oxidise easily.<br />• Sides must be parallel to allow ejection of part.<br />• Very good dimensional accuracy (near net-shape process) with 100% material utilisation.<br />• There can be problems with porosity – although sometimes this can be beneficial (e.g. filter,<br />bearings).<br />Economics<br />• The machinery is expensive, and can cost well over £100,000.<br />• The dies are dedicated, expensive (£5,000+) and need to be replaced after about ten thousand<br />uses. They can take several weeks to manufacture, mean prototype testing is slow.<br />• The production rate is dominated by the sintering stage and is therefore quite slow (2-20 per<br />hour).<br />• Tends only to be economic for large batches (50,000+) or processing high-strength alloys.<br />Typical products<br />• small gears<br />• magnets<br />• cutting tool tips<br />• light bulb filaments<br />• aircraft landing gear<br />• bearings (porous)<br />• filters<br />_________________________________________________________________________________<br />Polymer shaping (generic)<br />Related processes in this database include: Injection moulding, vacuum forming, blow moulding,<br />rotational moulding,, extrusion (polymers), compression moulding<br />Overview<br />• The biggest mistake with forming polymers is to design the products the same way as metal<br />products - it took 20-30 years from the introduction of polymer forming for many manufacturers<br />to use them well. For instance, because of the comparatively low strength and stiffness of most<br />polymers, "ribbing" is often incorporated into the design – this will have an effect on which<br />processes can be used.<br />• Generally, polymer products are formed near-net-shape and do not require further finishing.<br />This "one-stop" processing gives polymer processing a cost advantage over metal processing.<br />• Polymer processing basically splits into those suitable for thermosets and those suitable for<br />thermoplastics, although care must be taken over toxic fumes for both.<br />Polymer extrusion<br />Overview<br />Unlike metal extrusion, polymer extrusion is a continuous process. A useful variation of the process<br />called co-extrusion can be used (for example, to coat wires in-line for electrical cables). Polymer<br />extrusion is sometimes used as a 'melter' for feeding other shaping processes such as injection<br />moulding or blow moulding.<br />Materials and shapes<br />Mainly used for thermoplastics, but can be used with rubbers and some thermosets. Complex shapes<br />with constant cross-section can be easily formed. Because of shrinkage, die design can be difficult (and<br />hence expensive) if good dimensional accuracy is required. Near-net-shape process, only the ends of<br />the extrusion are wasted.<br />Economics<br />The cost of the machines is high - well over £50,000. Die design can be expensive; the actual dies<br />usually cost a few thousand pounds to produce and need replacing after 10-100km of extrusion.<br />Depending on size, parts can be extruded at rates from 1-60m/minute. Because of the high costs, it is<br />usually only economic to produce lengths over 10km - although there is little competition for many of<br />the possible shapes.<br />Typical products<br />Channels, pipes, sheet, architectural mouldings, cables, coated wires.<br />___________________________________________________________________________________<br />Peening<br />Other names / variants: Shot peening<br />Overview<br />• Peening is only used for metals.<br />• All metals can have their strength improved by ‘working’ them – i.e. deforming them past the<br />elastic limit. Peening only does this to the surface, by firing ‘shot’ (like small ball-bearings) at<br />it. This can result in greatly improved fatigue resistance (useful for components which undergo<br />cyclic loading such as turbine blades).<br />• Peening is flexible and relatively inexpensive unless significant automation is used.<br />• Peening can also be used for shaping thin sheets – but this isn’t a surface treatment!<br />___________________________________________________________________________________<br />Milling<br />Overview<br />Milling will be familiar to anyone with experience of a metal workshop. The machines used<br />industrially can be extremely sophisticated - the cutting head is often able to twist and turn in many<br />directions! As well as being used for many small products suitable for school workshops, milling has<br />been used for large scale items such as aeroplane wings and tanks!<br />Materials and shapes<br />Almost any material can be milled, although difficulties arise with very brittle materials (e.g. ceramics)<br />and very hard materials (e.g. tool steel). Milling is used in metals primarily to shape parts by cutting<br />edges, slots or grooves. It is often used to complete parts that have been formed by a near-net-shape<br />process (e.g. casting or forging). Milling is unusual for wooden products, although variants such as<br />routing can be used to form grooves and mouldings.<br />Economics<br />Milling machines vary in price from £1,000 to £1,000,000. Milling is generally a very slow way to<br />produce a component - but it can be economic for prototyping or small batches. High speed machining<br />centres are used where the accuracy of milling is required to finish a component. The cost of milling on<br />a commercial scale is often a balance between higher speed and longer tool-life.<br />Typical products<br />Finishing surfaces (e.g. top of engine block), wooden furniture, architectural mouldings<br />___________________________________________________________________________________<br />Metal shaping (generic)<br />Related processes in this database include: Forging, Die Casting, Lost Wax Casting, Sand Casting,<br />Extrusion (metal), Rolling, Sheet forming<br />Overview<br />Bulk metal shaping is generally done near-net-shape by forging or casting although further finishing<br />work is usually required. However, it does reduce the material wasted by machining and is usually<br />much faster. For many components, casting and forging are in direct competition and there is often no<br />easy way to decide which is the better choice; both are usually undertaken by specialist companies<br />(foundries and forges respectively).<br />There are a variety of sheet forming processes suitable for metals less than 6mm thick, and in general<br />all products based on sheet will be made using one of these processes. Sheet is made by rolling, which<br />is also used to produce most large stock items held by material suppliers and a few final products such<br />as I-beams.<br />Extrusion is also used to produce some stock items with constant cross-section, such as tubes, and<br />some finished items, such as window frames.<br />___________________________________________________________________________________<br />Metal extrusion<br />Overview<br />• Metal extrusion was developed in the late 18th century for making lead pipe. The basic process<br />of forcing a round billet through a shaped die is still used today.<br />• Modern variants can produce clad products in one go - e.g. copper clad with silver.<br />• Wire drawing is related to extrusion but is used for smaller (round) sections and the metal is<br />pulled through the die rather than pushed.<br />Materials and shapes<br />• Mainly used with the softer metals, e.g. aluminium, copper, zinc.<br />• Generally speaking, the softer the metal, the more intricate the shapes that can be made.<br />• Useful for long thin parts with constant cross-section.<br />• Possible cross-sections are usually less than 100mm across.<br />• Dimensional tolerance and surface finish may be poor with hot extrusion.<br />• Cold extrusion is possible for some metals giving better properties.<br />Economics<br />• Although extrusion appears to be a continuous process, it is really a batch process as it needs to<br />be interrupted to load new billets.<br />• Typical machine prices are in excess of £50,000.<br />• Dies can cost upwards of £1000 to make (depending on size), but a lot more to design well.<br />• More frequent die replacement is needed for higher strength metals.<br />• Production rates from 5-10metres/minute are possible.<br />• Usually only economic for several thousand metres +<br />Typical products<br />• Tubing<br />• aluminium window frames<br />• railings<br />• trims<br />• wires<br />___________________________________________________________________________________<br />Mechanical fastening<br />Other names / variants: rivets, snap-fits, screws, bolts, nuts<br />Related processes in this database include: Joining (generic)<br />Overview<br />Mechanical joining falls into two distinct groups: fasteners and integral joints. Examples of fasteners<br />include: nuts and bolts, screws, pins and rivets; examples of integral joints include: seams, crimps,<br />snap-fits and shrink-fits.<br />Some form of mechanical joining needs to be used where products need to be taken apart during their<br />normal life, e.g. where repair or maintenance is likely.<br />With the move towards efficient recycling, there is likely to be increased use of mechanical fastening.<br />Materials and shapes<br />• Virtually any material in any shape can be joined by mechanical fastening - given enough<br />ingenuity!<br />• Practical limitations come from being able to form holes - this limits the options for ceramics<br />and composites. Snap-fit joints are especially suitable for low stiffness materials like polymers.<br />• Especially good for joining different materials (e.g. composite to metal).<br />• Joint quality is reliable and readily determined, given sufficient operator skill. However,<br />mechanical joining usually reduces fatigue life.<br />• Essential where two parts will move relative to each other (e.g. hinges for doors).<br />• The non-permanence of many fasteners is useful for products that may need repair/maintenance<br />or need access to the interior.<br />Economics<br />• Can be economic for any batch size from one-offs to mass production (with or without<br />automation).<br />• Ease of mechanical joining (especially with snap fits) means low skilled workers can be used.<br />• For fasteners, there can be a significant stock cost in ordering and keeping track of so many<br />components!<br />• By far the dominant means of joining parts.<br />• Competes with welding for thick metallic sections where a permanent joint is needed.<br />• Competes with adhesives for polymers and woods where a permanent joint is needed.<br />___________________________________________________________________________________<br />Mechanical cutting<br />Other names / variants: Sawing, hacksaws, bandsaws, circular saws<br />Overview<br />One way of splitting a workpiece in two is to plastically press a shape out of it, such as with blanking.<br />This entry deals with splitting a workpiece in two by removing a thin slice of material by mechanical<br />means (the other main approach is removal by intense heat). These processes are usually called<br />"sawing" and include: hacksaws, bandsaws, circular saws and friction saws.<br />Other specialist cutting processes include gear cutters.<br />Materials and shapes<br />• Generally speaking, sawing is only for straight line cuts all the way through a workpiece.<br />• Some sawing processes are capable of producing curves, and some can be used for cutting<br />"slots".<br />• In general, wood and metals are easily cut - although the higher the strength of the metal the<br />greater the rate of wear on the cutting teeth.<br />• Polymers can be cut, but care must be taken to avoid any melting.<br />• Glass can be cut by "score-and-snap" techniques.<br />• Composites are not usually cut (other than edge trimming) after forming as it can have a serious<br />impact on the mechanical properties.<br />Economics<br />• If possible, avoid cutting! A surprising number of designs involve a cutting process followed by<br />a joining process. Although this can be more economical than making in one-piece, it is not<br />usually the case.<br />• The main use for cutting is to reduce stock items (usually from rolling or extrusion) to the<br />correct length.<br />• For thin workpieces (up to 6mm), mechanical cutting competes with sheet process such as<br />blanking.<br />• For thicker workpieces, new processes such as plasma-arc, water jet and lasers are becoming<br />competitive because of their greater flexibility.<br />Typical products<br />• I-beams<br />• window frames<br />• joists<br />• architectural mouldings<br />___________________________________________________________________________________<br />Machining (generic)<br />Related processes in this database include: drilling, milling, turning, mechanical cutting, grinding,<br />polishing<br />Overview<br />Machining is one of the most widely used types of process found in industry, particularly for metals.<br />There are many variants including milling, grinding and drilling — all share the common feature of<br />removing material with some form of cutting tool.<br />As it can be expensive, extensive machining of a product is limited to trials or low volume products. It<br />should be kept to a minimum for high volume products and so is not used for most consumer items.<br />Industrially, milling, turning and drilling are often combined in CNC machining centres which can<br />produce a wide variety of shapes at high speeds. These machines can contain over 200 different cutting<br />tools, which are automatically replaced as they wear out.<br />It is possible (but unusual) to machine polymers – care must be taken as they can melt. In addition,<br />machining polymers usually leaves a rough finish (they are normally smooth after moulding).<br />Mechanical cutting is a type of "machining" used to separate parts – the most commonly know<br />processes are saws.<br />___________________________________________________________________________________<br />Lost wax casting<br />Other names / variants: Investment casting<br />Overview<br />• Some form of lost wax casting has been used since 4000BC.<br />• It is now mainly used for medium size batches where good quality is required.<br />• The fine dust and harmful fumes require careful control of the workplace to avoid health<br />problems for operators.<br />Materials and shapes<br />• Suitable for most metals, leaving a good surface finish which usually does not require further<br />finishing steps.<br />• Best for small complex-shape parts, but can be used for parts from 5g to 100kg.<br />• Not much metal scrap, and it can be easily recycled. Wax can be re-used but ceramic coating<br />must be disposed of carefully.<br />Economics<br />• The production cycle is slow: usually only 1-5 castings can be made an hour, depending on the<br />size. Assembling lots of patterns on one tree can help in achieving a reasonable production rate.<br />• The basic cost of the equipment can be as little as £1,000, although automated kit can be a lot<br />more. The cost of the patterns is usually only a few hundred pounds, but they can take several<br />weeks to make.<br />• Although the setup costs are low, the low manual production rate means that only batch sizes of<br />up to 50 are economic; this can rise to a few thousand if automated.<br />Typical products<br />• Jewellery<br />• dental implants<br />• hip replacements<br />• valves<br />• wind instrument keys<br />___________________________________________________________________________________<br />Laser processing (generic)<br />Overview<br />Although lasers are often thought of as "sci-fi", they are a surprisingly versatile tool in manufacturing<br />and can be used for:<br />• Cutting of most metals (up to 30mm thick) and woods. Over 75% of lasers are currently used<br />for sheet metal cutting as they can provide accurate cuts at high speeds. Because there is no<br />contact, it doesn’t matter how hard the material is and there is no tool wear.<br />• Welding of most metals up to 20mm thick without the need for a filler. They can also be used<br />for high speed spot welding (used for Gillette razors).<br />• Drilling of burr-free precision holes with no further finishing required. A common application<br />is the cooling holes in turbine blades – it can be over 20x faster than competing techniques.<br />• Surface hardening of steel component - see transformation hardening for further details.<br />Other applications include paint removal and rapid prototyping. Industrial lasers start at about<br />£100,000, but because they are very flexible and easily automated they can often prove cost-effective<br />___________________________________________________________________________________<br />Joining (generic)<br />Related processes in this database include: Welding, Brazing, Adhesive bonding, Mechanical<br />fastening<br />Overview<br />• It is unusual for a product to be made in one-piece – almost all products consist of components<br />which must be joined in some way.<br />• The most familiar joining processes are probably mechanical fasteners and adhesives and, as a<br />result, designers often think they understand these the best. However, mechanical fastenings<br />such as snap-fits are often over looked and modern adhesives are greatly under-rated because<br />they are thought of as "just glue".<br />• In addition to these processes, there are a variety of "hot processes" such as welding and<br />brazing which can often provide stronger and more economic joints for metal parts.<br />• The one thing which is key for all the processes is to design the joint for the process, and not to<br />design the joint before deciding on the process – a good joint for welding can be disastrous for<br />adhesive bonding, and vice-versa.<br />• Joints are often a source of weakness in failure – they are very important in design.<br />Injection moulding<br />Overview<br />Essentially, injection moulding is die-casting for polymers. It is normally automated and used for high<br />speed, high volume production where component quality does not need to be high - over 50% of<br />polymer parts are produced this way.<br />The mark left by the ejector pin can often be seen on cheap mouldings. To increase the shapes possible,<br />sophisticated dies with moving and unscrewing inserts are used.<br />Injection moulding machine<br />[Pictures courtesy of Withersdale Plastics Ltd.]<br />Materials and shapes<br />• Thermoplastics dominate, but can also be used for thermosets, rubbers, polymer foams and<br />short-fibre composites.<br />• Can make intricate shapes, though not suitable for thick sections.<br />• Typical part sizes are 100-600g, although parts up to 25kg can be made at great expense.<br />• Parts generally do not require finishing, although parts for feeders etc. may require removal.<br />• A wide variety of surface finishes and embosses can easily be incorporated into the die design.<br />• Thermoplastic scrap is easily recycled, but other materials must be disposed of carefully.<br />Economics<br />• To reduce costs, several parts are often moulded together on a "tree-like" structure; parts can<br />then be separated after moulding.<br />• The cycle time is limited by solidification time and time to open and close the mould.<br />Production rates from 1-20 parts/minute are readily achievable.<br />• Capital cost for machines are from £10,000 - £100,000 and dies can cost between £1,000 and<br />£10,000.<br />• Injection moulding is only economic for batches of 10,000 - 100,000 or more and so is usually<br />automated.<br />Typical products<br />• toys,<br />• model-making kits,<br />• handles,<br />• food containers,<br />• cups,<br />• electrical and plumbing fittings<br />___________________________________________________________________________________<br />Grinding / Polishing<br />Overview<br />The basic principle of grinding is similar to that of using sand paper to smooth wood. Where it is used<br />it will be the final finishing operation, with the possible exception of painting. Although grinding<br />wheels (which can be up to 2m!) are commonly found in industry, they are being replaced by abrasive<br />belts. Unusually for a mechanical process, grinding usually works best with harder materials, rather<br />than softer materials.<br />Materials and shapes<br />Grinding and polishing are finishing operations used where great dimensional accuracy or a good<br />surface finish are required. Polishing often produces a lustrous surface finish - this is due to softening<br />and smearing of the surface from the frictional heating. Primarily used with metals and ceramics.<br />Although grinding does remove material, almost none of this can be recycled.<br />Economics<br />On an industrial scale, the wear on grinding equipment is significant and this adds greatly to the cost.<br />The variable wear on a grinding wheel makes control of automated equipment more difficult and hence<br />expensive. The production rate depends on the level of finish required - the limiting factor is usually<br />the overall cost. As with the other machining processes, grinding and polishing should be avoided if at<br />all possible<br />Glass forming<br />Overview<br />Sheet glass is produced by drawing, rolling, and floating. Drawing is also used to produce fibres, rods<br />and tubes.<br />Discrete glass products (e.g. bottles) are made by blowing, pressing and casting.<br />All these processes begin with molten glass (which looks like red-hot thick syrup). A further process,<br />called sagging, is useful for products with shallow curves (e.g. plates) or light embossings.<br />Materials and shapes<br />• There are over 750 types of glass, but they can all basically be formed in the same ways.<br />• Drawing and rolling give a rough finish which normally needs grinding and polishing. Float<br />glass has a smooth surface.<br />• A variant of drawing is used to make rods and tubes.<br />• Blowing is used to produce hollow thin-walled items; it is similar to blow moulding of<br />thermoplastics. The surface finish is acceptable for most applications.<br />• Pressing produces parts with greater dimensional accuracy, but cannot be used for items with<br />thin walls or inward curves.<br />Economics<br />• Production rates and costs strongly depend on the type of process and the size of component.<br />• The different processes are generally suited to different shapes, so there tends to be little<br />competition.<br />• Blowing of light bulbs takes place on expensive fully automated equipment, but over 1000<br />bulbs per minute can be formed.<br />• Fibre optics can be drawn at speeds of up to 500m/s.<br />Typical products<br />• table tops<br />• bottles<br />• vases<br />• television tubes<br />• windows<br />• headlights<br />• light bulbs<br />• mirrors<br />• dishes<br />• optical fibres<br />Friction welding<br />Overview<br />Welding is commonly thought of as a process where material is melted - this type of process is more<br />properly called fusion welding. However, there is another type of welding process, called hot welding,<br />where the material is heated until it softens but does not melt. Friction welding falls into the latter<br />category - the heating is provided by the rubbing of the parts to be joined (at speeds which can be up to<br />15m/s).<br />Materials and shapes<br />• Usually, at least one of the parts to be joined must be circular - this can be solid or hollow.<br />• One of the materials to be joined must soften before melting.<br />• Used to join different materials to each other (e.g. polymers to metals).<br />• Solid bars up to 100mm can be joined and pipes up to 250mm.<br />• Good joint quality depends on good alignment of parts and timing of the final forging together.<br />Economics<br />• Basic equipment costs around £10,000, but automation can increase this significantly.<br />• Most suited economically to joining pipes and attaching studs.<br />• For similar metals, competitive with arc welding for the geometries it can do. But because of the<br />capital cost, it is not competitive where only a small number of joints are required.<br />• Competitive with adhesives for polymers for the geometries it can do, especially for a large<br />number of joints.<br />• Removal of flash (if required) adds to the cost.<br />Typical products<br />• pipes<br />• studs<br />___________________________________________________________________________________<br />Forging<br />Other names / variants: ring-rolling, open-die forging, closed-die forging, drop forging<br />Related processes in this database include: metal extrusion<br />Overview<br />• Forging is probably the oldest metalworking process - dating back to at least 5000BC.<br />• It has advanced a long way from its "blacksmith" image and today there are many hi-tech<br />variants that compete mainly with the casting processes.<br />• Although forging can take place "cold", the component is usually heated to reduce the forces<br />required.<br />• The forging action can be extremely noisy!<br />Variants<br />• Impression Die Forging - also called closed die forging, presses metal between 2 dies that<br />contain a precut profile of the desired part.<br />• Cold Forging - includes bending, cold drawing, cold heading, coining, extrusions and more, to<br />yield a diverse range of part shapes. The temperature of metals being cold forged may range<br />from room temperature to several hundred degrees.<br />• Open Die Forging is performed between flat dies with no precut profiles is the dies. Movement<br />of the work piece is the key to this method. Larger parts over 20 tonnes and 10 metres in length<br />can be hammered or pressed into shape this way.<br />• Seamless Rolled Ring Forging is typically performed by punching a hole in a thick, round<br />piece of metal (creating a donut shape), and then rolling and squeezing (or in some cases,<br />pounding) the donut into a thin ring. Ring diameters can be anywhere from a few inches to 30<br />feet.<br />Process details<br />Closed-die forging<br />A heated blank is placed between 2 halves of a die<br />A single compressive stroke squeezes the blank into the die to form the part. In hammer or drop forging this happens<br />by dropping the top of the mould from a height. An alternative is to squeeze the moulds together using hydraulic<br />pressure.<br />Once the die halves have separated, the part can be ejected immediately using an ejector pin.<br />The waste material, flash, is removed later.<br />Materials and shapes<br />• Any metal can be forged, provided the blank is hot enough (( 60% of the melting temperature).<br />• Typical possible sizes for closed dies range from 10g to 10kg, depending on complexity.<br />• The part is left with good surface and mechanical properties, although cold-forging can perform<br />even better.<br />• Complex parts can be formed using a series of forging dies with increasing levels of detail.<br />• A draft (taper) angle has to be incorporated to allow easy removal of the part.<br />• Any waste material squeezed between the die halves, called flash, is readily recycled.<br />Economics<br />• Production rate is limited by the insertion and removal of the blank, so some form of<br />automation is often used.<br />• As a result, machines can cost £100,000+, but can produce many parts a minute (if small).<br />• As both the machines and the dedicated dies are costly, production runs in excess of 50,000 are<br />often needed to produce small parts economically.<br />• Large parts can be produced economically at smaller batch sizes, because there is less<br />competition.<br />Typical products<br />• Spanners<br />• pedal cranks<br />• gear blanks<br />• valve bodies<br />• hand tools<br />• crankshafts<br />• coins<br />___________________________________________________________________________________<br />Drilling<br />Other names / variants: Trepanning<br />Overview<br />One of the most common of the machining processes - as there are few other ways to produce a deep<br />circular hole. One of the biggest challenges to the drill designer is how to remove the waste material<br />out of the hole at the same time as getting the cutting fluid into the hole. Large shallow holes are made<br />by trepanning, where a disc is removed rather than all the material.<br />Materials and shapes<br />• Almost any material can be drilled, although difficulties arise with very brittle materials (e.g.<br />ceramics) and very hard materials (e.g. tool steel).<br />• Drilling is used for making circular holes, dimensional accuracy can be improved by subsequent<br />reaming or boring.<br />• Holes from 0.5 mm to 50mm are commonly drilled - although the design of the drill bit will<br />vary quite a lot!<br />• Drilling is often used to complete parts that have been formed by a near-net-shape process (e.g.<br />casting or forging) as precision holes are difficult to form with these processes.<br />• Threaded holes are made by first drilling a cylindrical hole and then "tapping" with a threaded<br />cutting tool.<br />Economics<br />• It is normal to try to reduce the amount of drilling required in a component by careful design -<br />but when an accurate hole is required, drilling has little competition.<br />• Where drilling is required industrially, it is usually done either as part of the function of a<br />machining centre, or in a dedicated drill set with multiple heads so that all the holes can be<br />made simultaneously<br />___________________________________________________________________________________<br />Die casting<br />Other names / variants: ferro-die casting<br />Overview<br />• Developed in the early 1900s, this is the most common of the casting processes that use a<br />permanent mould.<br />• It is used for high volume products, of which small zinc die-cast toys (e.g. "Matchbox" cars) are<br />probably the most widely known.<br />• Very small components like zipper teeth can be made at over 20,000 an hour!<br />Variants:<br />Ferro-die is used for high melting point materials such as steels. It uses higher melting point ferrous<br />alloys for the die materials and is more expensive.<br />Materials and shapes<br />• Mostly used for low melting point alloys such as aluminium, zinc and copper. In general only<br />small parts are made, but it can be used for components up to 25kg.<br />• Complex parts can be made with good dimensional accuracy and surface detail.<br />• A draft (taper) angle has to be incorporated to alloy easy ejection of the part.<br />• Parts are left with good mechanical surface properties.<br />• Ejector pin marks are often visible.<br />Economics<br />• The machinery is expensive, and can cost well over £100,000.<br />• Dies cost many thousand pounds and need to be replaced after a few hundred thousand uses.<br />They can take several weeks to manufacture, mean prototype testing is slow.<br />• The production rate depends on how long the part takes to cool before it can be ejected. This<br />can give rates of 500+ parts per hour in normal conditions.<br />• Because of the high capital cost, the process is only economic for batches of 100,000+<br />Typical products<br />• Small toys e.g. cars/soldiers<br />• hand tools<br />• disc drive chassis<br />• motor casings<br />• carburettors<br />Compression moulding<br />Overview<br />Essentially, this process is forging for polymers - although only one 'hit' is possible. Mainly used for<br />thermosets and rubbers in mid-size batches as injection moulding is cheaper for thermoplastics. With<br />thermosets, the chemical reaction provides most of the heat, so little extra energy is required.<br />Materials and shapes<br />Mainly used for thermosets, although rubbers, some thermoplastics and chopped-fibre composites can<br />be formed this way. Limited to simple shapes, although a wider variety is possible with rubbers as they<br />can be more easily removed from the mould. Possible part size range from 10mm up to 1m. Waste<br />material, called flash, needs to be removed after moulding and is not readily recycled.<br />Economics<br />Cycle time is limited by heat transfer, or curing time and is usually over 1 minute. Production rate can<br />be increased by using multiple cavity moulds. Equipment cost is low compared to similar processes -<br />about £10,000 - £50,000. Die cost a few thousand pounds, and need replacing after 10-50,000 uses. The<br />low production rate means that it is only usually economic for batch sizes in the tens of thousands.<br />Typical products<br />Dishes, handles, caps, electrical components.<br />___________________________________________________________________________________<br />Composite shaping (generic)<br />Overview<br />The unique structure of reinforced plastics requires special processes to shape them into useful<br />products. Although some of the polymer forming processes can be used (when the fibres are chopped<br />and mixed in a polymer), there are special processes which are specific to composites containing long,<br />continuous fibres (such as CFRP) – it is these that are discussed here. Many of the polymer resins used<br />can give off toxic fumes, so precautions have to be taken to protect operators from the adverse effects.<br />Design issues include:<br />• Avoiding sharp changes in section<br />• Orienting fibres where possible to improve mechanical properties<br />• Forming as close as possible to finished shape; drilling holes can dramatically reduce strength<br />A few years ago, fibreglass Formula 1 car bodies needed to be replaced after every race. New carbon<br />fibre and precision forming techniques mean that these bodies can now last all season.<br />___________________________________________________________________________________<br />Composite forming<br />Other names / variants: Hand lay-up, Resin transfer moulding (RTM), Spray-up, Pultrusion<br />Overview<br />The basic aim of all composite forming techniques is to mix a resin with a reinforcement (which may<br />be as woven mat, long fibres or chopped fibres) to produce the desired shape. This may be done by<br />using prepregs or performed in-situ. A variety of processes exist for various shapes and scales of<br />production.<br />Materials and shapes<br />• Hand lay-up is perhaps the most familiar process. It can be used for components of virtually<br />any size, but usually simple shapes. Similar shapes can be made by spray-up, which is faster<br />but more expensive. Both process can suffer from quality problems - these can be reduced by<br />using vacuum bagging.<br />• A variant of compression moulding, called resin transfer moulding (RTM), can be used to<br />make complex parts or where greater dimensional accuracy is required.<br />• Hollow parts can be made by filament winding which can produce parts with optimised<br />mechanical properties.<br />• Fibres, tapes and mats are produced by processes called pultrusion and continuous laminating;<br />these can also be used to produce prepregs (composite tapes and mats with resin that has not yet<br />cured).<br />Economics<br />• There are few composite forming processes, and the decision of which to use is normally<br />determined first by shape and type of fibre (chopped or continuous), and then by volume of<br />production.<br />• In general, composite forming is more expensive than in other material classes. This is primarily<br />because of the slow production rate due to the curing time of the resins.<br />• Hand lay-up equipment can cost under £100, but good quality moulds can cost significantly<br />more and have a lead time of several weeks. It is useful for prototyping or where only a few<br />parts are required.<br />• Spray-up, RTM and filament winding can be automated, so are usually used for mass<br />production.<br />• The wear on the dies from the fibres is significant in RTM, and they may need to be replaced<br />after every few thousand injections.<br />Typical products<br />Boat hulls, propeller blades, baths, water tanks, structural cables, rocket noses, turbine blades, golf<br />clubs, tennis racquets, bicycle frames<br />___________________________________________________________________________________<br />Ceramic shaping (generic)<br />Related processes in this database include: glass moulding, sintering, HIPping<br />Overview<br />There are several ceramic forming processes, although most of them are specific to individual materials<br />such as throwing for pottery, casting for concrete and slip casting for porcelain.<br />Because ceramics only melt at very high temperatures, most forming of “engineering ceramics” (like<br />alumina) is based on using dry powder or "bound" powder which can be moulded; at the dominant<br />method of forming engineering ceramics is sintering. An exception to this general rule is glass<br />forming, since glass softens sufficiently for it to be moulded.<br />Case hardening<br />Other names / variants: Carburising, Nitriding<br />Overview<br />Carburising and nitriding are both forms of case hardening and are primarily used to improve the<br />mechanical properties of the surfaces of steel components. The component to be treated is put into a<br />special gas atmosphere (gas carburising) at a high temperature. The process works by altering the<br />surface chemistry because of the diffusion of gas into the solid.<br />The process is quite slow because it depends on diffusion, so it is normally automated by using a<br />conveyor belt. It is also possible to use certain liquids (liquid carburising) which speed up the diffusion<br />so cycle times are shorter.<br />The main advantages of these processes are:<br />• only simple equipment is required and no dedicated tooling,<br />• and any shape can be treated, as long as the gas has a passage to the surface,<br />• large components can be treated in one go<br />the main disadvantages are:<br />• relatively slow,<br />• not easy to transform only parts of the surface<br />Blow moulding<br />Overview<br />Blow moulding is most commonly a batch process used to produce simple drinks bottles. Clever design<br />of the blank allows the screw top and base of bottles to be thicker than the walls.<br />Materials and shapes<br />• Used for simple, thin-walled, hollow products - mainly bottles<br />• Used with thermoplastics, mainly PET.<br />• Good, smooth surface finish can be readily achieved.<br />• Depending on how the hollow blank (parison) is made, scrap can be negligible.<br />• There is a variant which is continuous and used to produce thin-walled tubes which can be slit<br />to make cling-film or plastic bags.<br />Economics<br />• The production speed is limited by opening and closing the mould, so automation is normally<br />used.<br />• Production rates from a few hundred to a few thousand per hour can be achieved.<br />• The tooling and machines are moderately expensive (£10,000 - £100,000).<br />• Moulds may need to be replaced after about 100,000 uses.<br />• Only used for high volume products with batch sizes of 100,000+.<br />Typical products<br />Bottles and containers up to 0.5 litre<br />Arc welding<br />Other names / variants: MMA, TIG, MIG, spot welding, seam welding<br />Overview<br />• There are several types of arc welding - MMA (Manual Metal Arc) is probably the most well<br />known. Automated arc processes include TIG (Tungsten Inert Gas) and MIG (Metal Inert Gas).<br />All arc processes use a filler to join the two pieces - in MMA and MIG the filler also serves as<br />the electrode which makes the electric arc.<br />• There are other more specialist arc welding processes such as spot welding or seam welding<br />which work without a filler.<br />• Safety precautions must be taken to protect the welder from the bright arc and the noxious<br />fumes.<br />• Good welding requires a lot of skill, and in industry a welder must have special qualifications.<br />Materials and shapes<br />• Although many metals can be joined with MMA, it is most commonly used for steel. Other<br />materials, such as aluminium, are usually joined by more sophisticated arc welding processes<br />(e.g. MIG, TIG).<br />• MMA is portable and so suitable for repair or on-site work.<br />• Thin plates may require only one pass for a successful join. For thicker plates, multiple passes<br />may be required to fill the gap.<br />• For thin plates, the edges may be square. For greater thicknesses, the edges need to be bevelled<br />to allow the gap to be filled more easily.<br />• In the area that has been affected by heat, the properties of the material may change greatly.<br />Economics<br />• The cost of MMA equipment can be less than £100. However, the production rate is slow so it<br />is only economic for one-off jobs, repair work and difficult access situations.<br />• MIG and TIG are available as manual processes, but they are often automated to improve<br />quality and production rate.<br />• For joining thick metals, arc welding has few serious competitors.<br />• Where reliable joints are essential (e.g. aeroplane wings) mechanical fasteners such as rivets are<br />used instead of welding.<br />• Joining of sheet (e.g. car body panels) is usually more economic by other welding processes<br />such as spot welding.<br />Typical products<br />• Car bodies<br />• ships<br />• oil rigs<br />• pipelines<br />• pressure vessels<br />Adhesive bonding<br />Overview<br />Adhesive bonding was first used for load-bearing joints for aircraft in World War II. Significant<br />advances have been made in the technology since then, but it has still to be widely used industrially for<br />metals. Adhesives are available in many forms including: liquids, pastes, powders, tapes and films.<br />Adhesive bonding is often combined with mechanical joining - 'super glue' was first used to prevent<br />nuts on machinery shaking loose.<br />Materials and shapes<br />Any materials can be joined, although some may require special surface preparation. Especially useful<br />for joining different materials or very thin materials. The mechanical properties of adhesive joints can<br />be very good, but they usually have poor resistance to 'peeling'. The strength also deteriorates with<br />temperature and is rarely useful above 100-2500C. Adhesive joints can provide additional benefits as<br />well as joining, including: sealing, insulation, corrosion protection and vibration damping. Correct<br />design of the joint is essential for it to be strong. One method is to increase the area, so lap joints are<br />better than butt joints; another solution is to design interlocking joints and combine with another form<br />of mechanical joining.<br />Economics<br />Equipment costs (unless automation is required) can be low, although the cost of the adhesives<br />themselves can be significant. Where good joint quality is essential, special equipment such as fixtures,<br />presses and ovens are required which can significantly add to the cost. The production rate is often<br />limited by the curing time, which can range from a few seconds to many hours (think of 'super glue'<br />and 'araldite' as common household examples).<br />Typical products<br />car mirrors, brake linings, helicopter blades, laminated glass, packaging.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-74452234781564055002008-11-22T06:08:00.000-08:002008-12-23T01:17:25.195-08:00Piping ProblemsSummary:<br />There are several acoustic conditions that directly result in mechanical problems. The<br />reciprocating compressor problem is well known, and analysis techniques are long<br />established. Steamhammer and waterhammer problems and solutions are also readily<br />recognizable and solvable. More recently however, the prevention of dynamic problems<br />due to acoustic resonances has also received attention. The following case history<br />describes a typical example, where analysis beforehand would have tipped the designer<br />off to a condition that eventually led to failure. FE/Pipe finite element analysis was used<br />to verify that CAESAR II elbow loading conditions would produce the type of cracking<br />observed. A CAESAR II dynamic model of the piping system showed natural<br />frequencies at 5.06, 5.55 and 7.2 Hz. The fundamental acoustic natural frequency was<br />shown by BOS Fluids to be at 5.0 Hz. Leaving a gas relief system with mechanical and<br />acoustic natural frequencies that were identical resulted in the ultimate failure of this<br />system.<br />Discussion:<br />Fluid conditions known to cause resonance-type problems in piping systems are outlined<br />below:<br />1) Two phase flow. (Any volumetric percentage of liquid entrained in a gas<br />flow.)<br />2) Misty Flow. (A subset of two-phase flow.)<br />3) Gas flows in a boiling or flashing (furnace) environment.<br />4) Relief Valve Firing<br />5) Valve Cycling<br />6) Tube Rupture<br />7) Slugging (Typically not associated with acoustic resonance however.)<br />8) Pressure Regulated Flows (A subset of Valve Cycling)<br />9) Furnace Burner Gas Flows<br />10) Choked Flow<br />11) Flashing<br />Unexpected mechanical vibration problems can occur due to one or more of the<br />following events:<br />1) The piping system has low mechanical natural frequencies. (In the 5 Hz and<br />lower range, although sometimes “low” can be in the 20 Hz and lower range.<br />Low depends on the level of excitation present.) Low natural frequencies<br />commonly occur in hot piping systems that are excessively spring supported,<br />or in other piping systems that are inadequately supported.<br />2) Any of the above fluid events act on the system flow and produce a white<br />noise that will respond at the system acoustic natural frequency.<br />3) The acoustic natural frequency (determined by BOS Fluids) corresponds to a<br />mechanical natural frequency (calculated by CAESAR II).<br />Copyright 1999 by Paulin Research Group Page 2 of 2<br />Gas flows can be more troublesome than liquid flows because gas flows tend to have<br />lower acoustic natural frequencies. “Misty” flows usually have an even lower natural<br />frequency than a pure gas flow. Unexpected problems arise when low acoustic<br />resonances amplify the effect of the unbalanced pressure and low mechanical resonances<br />amplify the effect of the unbalanced displacement.<br />The following system experienced just such a problem.<br />When the relief valve failed the system vibrated, moving approximately 1.5” peak-topeak<br />in the vertical direction at the long riser section. Failure occurred at the first 45-<br />degree elbow.<br />Several pictures of the cracked geometry are shown below.<br />Copyright 1999 by Paulin Research Group Page 3 of 3<br />There were parallel cracks on each side of the bend shifted closer to the inside (or<br />intrados) of the elbow. A finite element plot of the high stresses in a 45-degree elbow<br />loaded via an out-of-plane moment is shown below.<br />The finite element runs were made to verify that external loads would produce the type of<br />stress pattern needed to cause the cracking observed. The plots of the elbow shown<br />above do just that. The plot on the right shows the high stress zones exactly where the<br />parallel cracking in the actual 45-degree elbow occurred. Stress Intensification Factors<br />from the FE/Pipe finite element calculation for the 45-degree elbows matched the B31.3<br />Code values as shown below:<br />Code FE<br />Outplane 1.948 1.60<br />Inplane 2.338 1.912<br />Plots of several of the system natural frequencies as calculated by CAESAR II are shown<br />in the figures below:<br />Copyright 1999 by Paulin Research Group Page 4 of 4<br />The CAESAR II model of the piping system was imported into BOS Fluids and the<br />following acoustic natural frequencies were generated from BOS Fluids.<br />The strongest acoustic mode exists at almost exactly 5 Hz. This system is clearly prone<br />to suffer acoustically excited mechanical resonance when the relief valve opens sending a<br />pressure wave back through the system. Pressure waves of this type require only 5 backand-<br />forth trips in the piping system to fully excite the mechanical natural frequency.<br />With a wavespeed of 600 ft./sec. the mechanical resonant multiplication of the response<br />is seen quickly.<br />Additional supports were added to remove the mechanical dynamic modes as best as<br />possible. A harmonic simulation using CAESAR was employed to simulate the required<br />dynamic excitation to cause the observed displacement. Markl’s equation to failure, and<br />an FE/Pipe validation of the piping stress intensification factors, were used to show that<br />thru-wall cracking at the observed displacements could occur in less than 10 minutes.<br />Copyright 1999 by Paulin Research Group Page 5 of 5<br />Markl’s equation to failure, which can be used with CAESAR II or B31.3 expansion<br />stresses, or FE/Pipe and ASME Section VIII Division 2, Pl+Pb+Q+F stresses is:<br />Sfail = 490,000 N-0.2 psi.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-11293066480733095322008-11-22T06:03:00.000-08:002008-12-23T01:17:25.195-08:00Kinematics of Gears• Gears are toothed, cylindrical wheels used for transmitting motion and power from one rotating shaft to another.<br />• The teeth of a driving gear mesh accurately in the spaces between teeth on the driven gear.<br /><br /><br />Speed Reduction Ratio<br />• Often gears are employed to produce a change in the speed of rotation of the driven gear relative to the driving gear.<br />• If the smaller top gear (pinion) is driving the larger, lower gear (gear), the larger gear will rotate more slowly.<br />• The amount of speed reduction is dependent on the ratio of the number of teeth in the pinion to the number of teeth in the gear according to: – np / ng = NG / NP<br /><br />Kinds of Gears<br />• The major types of gears are:<br />– Spur gears<br />– Helical gears<br />– Bevel gears<br />– Worm/wormgear sets<br /><br />Kinds of Gears con’t<br />• Spur gears have teeth that are straight and arranged parallel to the axis of the shaft that<br />carries the gear.<br />• The curved shape of the faces of the spur gear teeth have a special geometry called an<br />involute curve.<br />• This shape makes it possible for two gears to operate together with smooth, positive<br />transmission of power.<br /><br />Kinds of Gears con’t<br />• The teeth of helical gears are arranged so that they lie at an angle with respect to the axis of the shaft.<br />• The angle, called the helix angle, can be virtually any angle.<br />• Typical helix angles range from approximately 10o to 30o, but angles up to 45o are practical.<br />• The helical teeth operate more smoothly than equivalent spur gear teeth, and stresses are lower.<br /><br />Kinds of Gears con’t<br />• Bevel gears have teeth that are arranged as elements on the surface of a cone.<br />• The teeth of straight bevel gears appear to be similar to spur gear teeth, but they are tapered, becoming<br />wider at the outside and narrower at the top of the cone.<br />• Bevel gears typically operate on shafts that are 90o to each other.<br />• Specially designed bevel gears can operate on shafts that are at some angle other than 90o.<br /><br />Kinds of Gears con’t<br />• When both bevel gears in a pair have the same number of teeth, they are called miter gears and are used only to change the axes of the shafts to 90 degrees.<br />• No speed change occurs.<br />• A rack is a straight gear that moves linearly instead of rotating.<br />• When a circular gear is mated with a rack, the combination is called a rack and pinion drive.<br /><br />Kinds of Gears con’t<br />• A worm and its mating wormgear operate on shafts that are at 90o to each other.<br />• They typically accomplish a rather large speed reduction ratio compared to other types of gears.<br />• The worm is the driver, and the wormgear is the driven gear.<br />• The teeth on the worm appear similar to screw threads, and are called threads rather than teeth.<br /><br />Spur Gear Styles<br />• When gears are large, the spoked design in part (a) is often used to save weight.<br />• The gear teeth are machined into a relatively thin rim that is held by a set of spokes connecting<br />to the hub.<br />Mott, Machine Elements in Mechanical Design, 2003<br /><br />Spur Gear Styles con’t<br />• A keyway is usually machined into the bore to allow a key to be inserted for positive transmission of torque <br />• The solid hub design is typical of smaller spur gears.<br />• When spur gear teeth are machined into a straight, flat bar, the assembly is called a rack.<br />• The rack is essentially a spur gear with an infinite radius.<br /><br />Spur Gear Geometry Involute-<br />Tooth Form<br />• The most widely used spur gear tooth form is the full-depth involute form.<br />• When two such gear teeth are in mesh and rotating, there is a constant angular velocity ratio between them: From the moment of initial contact to the moment of disengagement, the speed of the driving gear is in a constant proportion to the speed of the driven gear.<br />• The resulting action of the two gears is very smooth.<br /><br />Spur Gear Nomenclature<br />• One of the most important observations that can be made is that throughout the<br />engagement cycle there are two circles, one from each gear, that remain tangent.<br />• These are called the pitch circles.<br />• The diameter of the pitch circle of a gear is its pitch diameter; the point of tangency is<br />the pitch point.<br /><br />Spur Gear Nomenclature con’t<br />• When two gears mesh, the smaller gear is called the pinion, and the larger is the gear.<br />• The symbol DP indicates the pitch diameter of the pinion.<br />• The symbol DG indicates the pitch diameter of the gear.<br />• When referring to the number of teeth, use<br />NP for the pinion and NG for the gear.<br />Pitch<br />• The spacing between adjacent teeth and<br />the size of the teeth are controlled by the<br />pitch of the teeth.<br />• Three types of pitch designation systems<br />are in common use for gears:<br />1. Circular pitch<br />2. Diametral pitch<br />3. The metric module<br />Pitch con’t<br />• Circular pitch, p, is the distance from a<br />point on a tooth of a gear at the pitch circle<br />to a corresponding point on the next<br />adjacent tooth, measured along the pitch<br />circle.<br />• To compute the value of the circular pitch,<br />take the circumference of the pitch circle<br />and divide it into a number of equal parts<br />corresponding to the number of teeth in the<br />gear.<br />Pitch con’t<br />• The pitch of two gears must be identical.<br />• P = πDG / NG = πDP / NP<br />• The diametral pitch system, Pd, is the most<br />common pitch system used today in the US<br />(the number of teeth per inch of pitch<br />diameter).<br />• Pd = NG /DG = NP / DP<br />Gear-tooth Size as Function of<br />Diametral Pitch<br />Mott, Machine Elements in Mechanical Design, 2003<br /><br />Metric Module System<br />• The pitch of gears in the metric system is<br />based on this unit and is designated the<br />module, m.<br />• To find the module of a gear, divide the<br />pitch diameter of the gear in millimeters by<br />the number of teeth.<br />• m = DG / NG = DP / NP<br />Backlash<br />• If the tooth thickness were made identical in<br />value to the tooth space, as it theoretically<br />is, the tooth geometry would have to be<br />absolutely precise for the gears to operate,<br />and there would be no space available for<br />lubrication of the tooth surfaces.<br />• To alleviate these problems, practical gears<br />are made with the tooth space slightly larger<br />than the tooth thickness, the difference<br />being called the backlash.<br />Backlash<br />• To provide backlash, the cutter generating<br />the gear teeth can be fed more deeply into<br />the gear bank than the theoretical value on<br />either or both of the mating gears.<br />• The magnitude of backlash depends on the<br />desired position of the gear pair and on the<br />size and the pitch of the gears.<br /><br />Pressure Angle<br />• The pressure angle is the angle between the<br />tangent to the pitch circles and the line drawn<br />normal (perpendicular) to the surface of the gear<br />teeth.<br />Mott, Machine Elements in Mechanical Design, 2003<br />Pressure Angle con’t<br />• The normal line is sometimes referred to as<br />the line of action.<br />• When two gear teeth are in mesh and are<br />transmitting power, the force transferred<br />from the driver to the driven gear tooth acts<br />in a direction along the line of action.<br />Full-Depth, Involute-Tooth Form<br />Φ is the pressure angle.<br />Mott, Machine Elements in Mechanical Design, 2003<br /><br />Contact Ratio<br />• When two gears mesh,it is essential for<br />smooth operation that a second tooth begin<br />to make contact before a given tooth<br />disengages.<br />• The term contact ratio is used to indicate the<br />average number of teeth in contact during<br />the transmission of power.<br />• A recommended minimum contact ratio is<br />1.2 and typical spur gear combinations often<br />have values of 1.5 or higher.<br />Contact Ratio con’t<br />• The contact ratio is defined as the ratio of<br />the length of the line-of-action to the base<br />pitch for the gear.<br />• The line-of-action is the straight-line path of<br />a tooth from where it encounters the outside<br />diameter of the mating gear to the point<br />where it leaves engagement.<br />Contact Ratio con’t<br />• A convenient formula for computing the contact<br />ratio is:<br />• Where ϕ = pressure angle<br />• RoP = outside radius of the pinion<br />– DoP / 2 = (NP + 2) / (2Pd)<br />• RbP = radius of the base circle for pinion<br />– DbP / 2 = (DP / 2) cos ϕ = (NP / 2Pd) cos ϕ<br />φ<br />− + − − φ<br />=<br />cos<br />2 2 2 2 sin<br />p<br />m R R R R C oP bP oG bG<br />f φ<br />− + − − φ<br />=<br />cos<br />2 2 2 2 sin<br />p<br /><br />Interference Between Mating<br />Spur Teeth<br />• For certain combinations of numbers of teeth in a<br />gear pair, there is interference between the tip of<br />the teeth on the pinion and the fillet or root of the<br />teeth on the gear.<br />• The probability that interference will occur is<br />greatest when a small pinion drives a larger gear,<br />with the worst case being a small pinion driving a<br />rack.<br />• The surest way to prevent this is to control the<br />minimum number of teeth in the pinion to the<br />limiting values shown on the next slide.<br />Mott, Machine Elements in Mechanical Design, 2003<br />Velocity Ratio<br />• Without slipping there is no relative motion<br />between the two pitch circles at the pitch<br />point, and therefore the linear velocity of a<br />point on either pitch circle is the same.<br />• Use the symbol vt for this velocity.<br />• The linear velocity of a point that is in<br />rotation at a distance R from its center of<br />rotation and rotating with an angular<br />velocity, w, is found from vt = Rw.<br />11<br />Mott, Machine Elements in Mechanical Design, 2003<br />Velocity Ratio con’t<br />• Using the subscript P for the pinion and G<br />for the gear for two gears in mesh:<br />– vt = RPwP<br />– vt = RGwG<br />• Velocity ratio is defined as:<br />– VR = wP / wG = RG / RP<br />Train Value<br />• When more than two gears are in mesh, the<br />term train value (TV) refers to the ratio of<br />the input speed (for the first gear in the<br />train) to the output speed (for the last gear<br />in the train). By definition the train value is<br />the product of the values of VR for each<br />gear pair in the train.<br />• A gear pair is any set of two gears with a<br /><br />Double-Reduction Gear Train<br />Mott, Machine Elements in Mechanical Design, 2003<br />Train Value<br />• TV = (NB / NA)*(ND / NC)<br />• TV = product of number of teeth in the driven gears<br />product of number of teeth in the driving gears<br />• This is the form for train value that is used most often<br />Train Value con’t<br />• The velocity ratios are:<br />– VR1 = nA / nB<br />– VR2 = nC / nD<br />• The train value is:<br />– TV = (VR1)(VR2) = (nA / nB)(nC / nD)<br />• But because they are on the same shaft, nB =<br />nC, and the preceding equation reduces to:<br />– TV = nA / nD<br /><br />Idler Gear<br />• Any gear in a gear train that performs as<br />both a driving gear and a driven gear is<br />called an idler gear, or simply an idler.<br />• The main features of an idler are:<br />– An idler does not affect the train value of a gear<br />train because, since it is both a driver and a<br />driven gear, its number of teeth appears in both<br />the numerator and the denominator of the train<br />value equation.<br />Idler Gear con’t<br />– Placing an idler in a gear train causes a<br />directional reversal of the output gear.<br />– An idler gear may be used to fill a space<br />between two gears in a gear train when the<br />desired distance between their centers is greater<br />than the center distance for the two gears alone.<br />Internal Gear<br />• An internal gear is one for which the teeth<br />are machined on the inside of a ring instead<br />of on the outside of a gear blank.<br />14<br />Internal Gear Driven By an<br />External Pinion<br />Mott, Machine Elements in Mechanical Design, 2003<br />Velocity of a Rack<br />• The function of a rack-and-pinion drive is to<br />produce a linear motion of the rack from the<br />rotational motion of the driving pinion.<br />• The linear velocity of a rack, vR, must be<br />the same as the pitch line velocity of the<br />pinion, vt.<br />– vR = vt = RPwP = (DP / 2)wP<br />Rack Driven by a Pinion<br />Mott, Machine Elements in Mechanical Design, 2003<br /><br />Helical Gear Geometry<br />• Helical and spur gears are distinguished by<br />the orientation of their teeth.<br />• On spur gears, the teeth are straight and are<br />aligned with the axis of the gear.<br />• On helical gears, the teeth are inclined at an<br />angle with the axis, that angle being called<br />the helix angle.<br />Helix Angle<br />• The helix for a given gear can be either left-hand<br />or right-hand.<br />• The teeth of a right-hand helical gear would appear<br />to lean to the right when the gear is lying on a flat<br />surface and vice versa for the left-hand gear.<br />• In normal installation, helical gears would be<br />mounted on parallel shafts.<br />• To achieve this arrangement, it is required that one<br />gear be of the right-hand design and that the other<br />be of the left-hand with an equal helix angle.<br />Helix Angle<br />• If both gears in mesh are of the same hand,<br />the shafts will be at 90o to each other.<br />– Such gears are called crossed helical gears.<br />• The parallel shaft arrangement for helical<br />gears is preferred because it results in a<br />much higher power-transmitting capacity<br />for a given size of gear than the crossed<br />helical arrangement.<br /><br />Helical Gears<br />Mott, Machine Elements in Mechanical Design, 2003<br />Bevel Gear Geometry<br />• Bevel gears are used to transfer motion between<br />nonparallel shafts, usually at 90o to one another.<br />• The 4 primary styles of bevel gears are straight<br />bevel, spiral bevel, zero spiral bevel, and hypoid.<br />• The surface on which bevel gear teeth are<br />machined is inherently a part of a cone.<br />• The differences occur in the specific shape of the<br />teeth and in the orientation of the pinion relative to<br />the gear.<br />Straight Bevel Gears<br />• The teeth of a straight bevel gear are straight and<br />lie along an element of the conical surface.<br />• Lines along the face of the teeth through the pitch<br />circle meet at the apex of the pitch cone.<br />• The centerlines of both the pinion and the gear<br />also meet at this apex.<br />• In the standard configuration, the teeth are tapered<br />toward the center of the cone.<br /><br />Types of Bevels<br />Mott, Machine Elements in Mechanical Design, 2003<br />Spiral Bevel Gears<br />• The teeth of a spiral bevel gear are curved<br />and sloped with respect to the surface of the<br />pitch cone.<br />• Spiral angles, ψ, of 20o to 45o are used, with<br />35o being typical.<br />Zero Spiral Bevel Gears<br />• The teeth of a zero spiral bevel gear are<br />curved somewhat as in a spiral bevel gear,<br />but the spiral angle is zero.<br />• These gears can be used in the same<br />mounting as straight bevel gears, but they<br />operate more smoothly.<br />Hypoid Gears<br />• The major difference between hypoid gears and<br />the others is offset either above or below the<br />centerline of the gear.<br />• The teeth are designed specially for each<br />combination of offset distance and spiral angle of<br />the teeth.<br />• A major advantage is the more compact design<br />that results, particularly when applied to vehicle<br />drive trains and machine tools.<br />Types of Wormgearing<br />• Wormgearing is used to transmit motion<br />and power between nonintersecting shafts,<br />usually at 90o to each other.<br />• The drive consists of a worm on the highspeed<br />shaft which has the general<br />appearance of a power screw thread: a<br />cylindrical, helical thread.<br />• The worm drives a wormgear, which has an<br />appearance similar to that of a helical gear.<br />Types of Wormgearing con’t<br />• Worms and wormgears can be provided with<br />either right-hand or left-hand threads on the<br />worm.<br />• Several variations of the geometry of wormgear<br />drives are also available.<br />• The most common one employs a cylindrical<br />worm mating with a wormgear having teeth that<br />are throated, wrapping partially around the<br />worm.<br />– This is called a single-enveloping type of<br />wormgear.<br />Mott, Machine Elements in Mechanical Design, 2003Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-54424683412564272072008-11-19T08:22:00.001-08:002008-12-23T01:17:25.195-08:00Generalizing Pythagoras and CarnotConsider a circle of radius r centered on the point Pc, and an arbitrary point P0 at a distance R from Pc. We then draw a line through P0 intersecting the circle in the points P1 and P2 as shown below.<br /><br /><br /><br />The angles with which the circular locus cuts across the line at the points P1 and P2 are equal and opposite (i.e., complementary), so if we rotate the line incrementally about the point P0, the lengths of the segments P0P1 and P0P2 will change at a rate always proportional to their current lengths, and these rates of change will have opposite signs. Letting L1 and L2 denote these two distances, we have dL1/L1 = dL2/L2, which implies L1dL2 + L2dL1 = d(L1L2) = 0. Therefore, the product of these two distances is constant. To determine the value of this constant, we need only rotate the line so that is passes through Pc as shown below, and then note that the distances from P0 to the points of intersection are Rr and R+r, so their constant product is R2 – r2.<br /><br /><br /><br />On the other hand, if we rotate the line so that it’s tangent to the circle, the points P1 and P2 coincide, both at a distance L from P0, and the line from Pc to the point of tangency is perpendicular to the tangent line, as shown below. In this case our proposition gives the relation L2 = R2 – r2, which is Pythagoras’ theorem.<br /><br /><br /><br />Thus the Pythagorean theorem L2 = R2 – r2 can be seen as just a special case of the more general proposition L1L2 = R2 – r2. Incidentally, the same relation applies even if P0 is inside the circle, provided we treat the lengths L1 and L2 as signed quantities depending on their direction from P0. Since the product of the two distances from a point to the circle along any given line is constant, we can immediately infer the “hyperbolic” form of Pythagoras’ theorem, L1L2 = h2, from the figure below, where the line along L1 and L2 is a diagonal of the circle. (By completing the rectangle, we can see that the upper vertex is a right angle.)<br /><br /><br /><br />In Propositions 35 and 36 of Book III of Euclid’s Elements the proposition L1L2 = R2 – r2 is proved by mean of Pythagoras’ theorem, as shown in the figure below.<br /><br /><br /><br />We drop the perpendicular h from Pc to the line P1 P2, and then note that the product of the segments P0P1 and P0P2 is (st)(s+t) = s2 – t2. Also, the Pythagorean theorem gives s2 = r2 – h2 and t2 = R2 – h2, so the product of our two line segments is r2 R2. This is a nice proof, but it’s reliance on the Pythaogrean theorem prevented Euclid from placing it in Book I. Compare this with our previous proof, which consisted of the observation that as the line P1P2 rotates about P0 the segments P0P1 and P0P2 vary at rates always proportional to their lengths, one increasing and the other decreasing, so their product is constant. Admittely this is essentially a calculus argument, which Euclid would probably not have considered acceptable, but it bears a strong resemblence to some of the arguments used by Archimedes several centuries later. If Euclid had found a way to prove this proposition with invoking his I.47, he could then have immediately proved I.47 based on this result.<br /><br />The proposition L1L2 = R2 – r2 represents an algebraic relation between a set of distances r, R, L1, and L2 defined in terms of orthogonal coordinate differences by the basic function<br /><br /><br /><br />The distance between the points Pi and Pj is defined as f(xixj, yiyj). Assigning the point P0 to the origin of our coordinate system, we can express the proposition as<br /><br /><br /><br />where P1 and P2 are the intersections of any line through the origin with the locus defined by f(xxc,yyc) = r. Letting n denote the degree of the base polynomial (so n = 2 in this case), we can write this in the form<br /><br /><br /><br />It turns out (as shown in the article on A Quadrilateral in a Circle) that this proposition is true for any arbitrary homogeneous polynomial f of any degree n in any number of variables. Also, we can convert any polynomial to a homogeneous one in a higher dimension. To illustrate, consider a simple cubic curve<br /><br /><br /><br />This locus is not expressed in homogeneous form, but if we define X = x/z and Y = y/z we can substitute into this equation to give the homogeneous surface in three dimensions<br /><br /><br /><br />We now define the function<br /><br /><br /><br />On the plane w = 1 with u = X and v = Y this is our original cubic curve, so we choose the “center” point xc = yc = 0, zc = 1, and consider the locus of points such that<br /><br /><br /><br />On the plane z = 0 this locus is our original cubic. We choose to evaluate the intersections of this curve with the line through the origin with the slopes ky = 0 and kz = 0, so we know the intersection points are at x1 = 2, x2 = 3, and x3 = 5. Noting that r = 0, the theorem gives us the relation<br /><br /><br /><br />Both sides evaluate to 30, confirming the equality. It follows that if we tilt the line through the origin by setting ky to some non-zero value, the product of the f-functions of the coordinates of the three new points of intersection with our original cubic is always 30. Morevoer, we can tilt the line in the z direction by setting kz to some non-zero value, and still the product of the f-function of the coordinates of the three points of insection with the cubic surface is 30, even if we tilt the line to such an extent that the points of intersection have complex coordinates.<br /><br />In a sense, the “f-function” serves as a kind of “distance” function, but of course it isn’t the literal distance, unless f happens to be the metric function<br /><br /><br /><br />However, our proposition can still give us information about the relations between the literal distances. Consider the locus of points satisfying f(xxc,yyc,zzc) = r where f is an arbitrary homogeneous polynomial of degree n. Letting P1, P2,… Pn denote the points of intersection of the line given by y = kyx, z = zyx, we can write our basic proposition in the form<br /><br /><br /><br />In general the left-hand side is not the product of the literal distances, but we can form the product of the literal distances if we simply divide by f(1,ky,kz) and then multiply by the metric function g(1,ky,kz). Thus we have<br /><br /><br /><br />where L1, L2, … Ln are the literal distances from the origin to the points of intersection P1, P2, …, Pn. Obviously this product is not invariant because it depends on the slopes of the line, but the quantity in the square brackets is invariant for any given focal point in relation to the “center” of the locus. Thus the product of distances from a given focal point P0 to a locus along a line with the slopes , can be factored as F(P0)G(,) where the function F depends only on the focal point and the function G depends only on the slopes of the line.<br /><br />Now consider a set of m arbitrary points, denoted by Q1, Q2, …, Qm, and the cycle of m lines Q1Q2, Q2Q3, …, QmQ1. Let the slopes of the line from Qj to Qj+1 be denoted by j and j, and let j,k denote the product of the literal distances from Qj to the locus along the line from Qj to Qk. Then we have<br /><br /><br /><br />Each of the points has another set of distances to the curve, taken along the other line passing through that point, and we can evaluate the product of those products as<br /><br /><br /><br />Both of the above products consist of the same factors, so we have the relation for the products of the literal distances<br /><br /><br /><br />This corresponds to Carnot’s theorem on transversals, generalized to cycles of arbitrary length. We can immediately generalize it still further, because the relation applies not just to the products of the literal distances, but to the products of any homogeneous function of the coordinate differences. To see this, simply replace the metric function g with any other function. It also follows that the ratio of any function of the coordinate differences from any two given points to a curve along parallel lines (with arbitrary slopes) is invariant. So, for example, in the figure below, the product of the distances from A to S divided by the product of the distances from B to S is the same, regardless of whether the distances are evaluated along the two solid lines or the two dashed lines (or any other pair of parallel lines through the points A and B).Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-15676942305339787282008-11-19T08:21:00.001-08:002008-12-23T01:17:25.195-08:00Constructing the HeptadecagonThe ancient Greek geometers devoted considerable thought to the<br />question of which regular n-gons could be constructed by straightedge<br />and compass. They knew how to construct an equilateral triangle<br />(3-gon), a square (4-gon), and a regular pentagon (5-gon), and of<br />course they could double the number of sides of any polygon simply<br />by bisecting the angles, and they could construct the 15-gon by<br />combining a triangle and a pentagon. For over 2000 years no other<br />constructible n-gons were known.<br /><br />Then, on 30 March 1796, the 19 year old Gauss discovered that it<br />was possible to construct the regular heptadecagon (17-gon). (This<br />discovery apparently convinced him to pursue a career in mathematics<br />rather than philology.) The result was announced in the "New<br />Discoveries" column of the journal "Intellegenzblatt der allgemeinen<br />Litteraturzeitung" on 1 June 1796 by A. W. Zimmermann, a professor<br />at the Collegium Carolinum and an early mentor of the young Gauss.<br /><br />Subsequently Gauss presented this result at the end of Disquistiones<br />Arithmeticae, in which he proves the constructibility of the n-gon<br />for any n that is a prime of the form 2^(2^k) + 1, also known as<br />Fermat primes. Gauss's Disquisitiones gives only the algebraic<br />expression for the cosine of 2pi/17 in terms of nested square<br />roots, i.e.,<br /><br /> cos(2pi/17) = -1/16 + 1/16 sqrt(17) + 1/16 sqrt[34 - 2sqrt(17)]<br /><br /> + 1/8 sqrt[17 + 3sqrt(17) - sqrt(34-2sqrt(17)) - 2sqrt(34+2sqrt(17)]<br /><br />which is just the solution of three nested quadratic equations. <br />Interestingly, although Gauss states in the strongest terms (all<br />caps) that his criteria for constructibility (based on Fermat<br />primes) is necessary as well as sufficient, he never published a<br />proof of the necessity, nor has any evidence of one ever been<br />found in his papers (according to Buhler's biography).<br /><br />One of the nicest actual constructions of the 17-gon is Richmond's<br />(1893), as reproduced in Stewart's "Galois Theory". Draw a circle<br />centered at O, and choose one vertex V on the circle. Then locate<br />the point A on the circle such that OA is perpindicular to OV, and<br />locate point B on OA such that OB is 1/4 of OA. Then locate the<br />point C on OV such that angle OBC is 1/4 the angle OBV. Then find<br />the point D on OV (extended) such that DBC is half of a right angle.<br /><br />Let E denote the point where the circle on DV cuts OA. Now draw a<br />circle centered at C through the point E, and let F and G denote<br />the two points where this circle strikes OV. Then, if perpindiculars<br />to OV are drawn at F and G they strike the main circle (the one<br />centered at O through V) at points V3 and V5, as shown below:<br /><br /><br /><br />The points V, V3, and V5 are the zeroth, third, and fifth vertices<br />of a regular heptadecagon, from which the remaining vertices are<br />easily found (i.e., bisect angle V3 O V5 to locate V4, etc.).<br /><br />Gauss was clearly fond of this discovery, and there's a story that<br />he asked to have a heptadecagon carved on his tombstone, like the<br />sphere incribed in a cylinder on Archimedes' tombstone. The story<br />is probably apochryphal, because if Gauss had seriously wanted such<br />a monument located in the proximity of his actual remains, it would<br />have to be placed, not at his grave site, but above the jar in the<br />anatomical collection of the University of Gottingen where his brain<br />has been preserved (rather goulishly, in my opinion). On the other<br />hand, if proximity to the actual remains is not important, then the<br />heptadecagon on the monument to Gauss in his native town of Brunswick,<br />or even the figure above, may suffice.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-11247365565207490052008-11-19T08:20:00.002-08:002008-12-23T01:17:25.196-08:00Five Squarable LunesConsidering that it's impossible to "square the circle" by Euclidean<br />methods, it's interesting that some regions whose boundaries are<br />circular arcs CAN be "squared" by Euclidean methods - meaning that we<br />can construct a square with the same area using just straightedge and<br />compass - whereas most such regions cannot. Hippocrates of Chios was<br />the first to demonstrate such "quadratures" (around 440 BC) for lunes.<br />It turns out that only five particular lunes can be "squared". Three<br />of these were described by Hippocrates himself, and two more were<br />discovered in the mid 1700's. These last two are often credited to<br />Euler in 1771, but according to Heath all five squarable lunes were<br />given in a dissertation by Martin Johan Wallenius in 1766. It's now<br />known (Tschebatorew and Dorodnow) that these five cases are the ONLY<br />lunes that are squarable by Euclidean methods.<br /><br />It's not too difficult to discover these five squarable lunes,<br />especially with the help of modern trigonometric methods. In general,<br />consider the lune described by arc segments of two offset circles,<br />one of radius r and the other of radius R, as shown below.<br /><br /> <br /><br />Under what conditions can we solve for the area of the lune (the<br />shaded region) by Euclidean methods? This is equivalent to asked<br />for the conditions in which we can solve for the shaded area by<br />means of nothing more complex than quadratic equations and square<br />roots. The area of the lune can be expressed as the difference<br />between the two part-circular regions to the right of the vertical<br />line, i.e., we have<br /><br /> Area of Lune = [Area of CFD] - [Area of CED]<br /><br />We can express the area of the region CFD as follows<br /><br /> Area of CFD = [Area of sector BCFD] - [Area of triangle BCD]<br /><br />Now, since the area of a cmplete circle of radius r is pi r^2, the<br />area of the circular sector BCFD is simply<br /><br /> 2b<br /> --- [pi r^2] = b r^2<br /> 2pi<br /><br />Also, the area of the triangle BCD is<br /><br /> 1<br /> [r sin(b)][r cos(b)] = --- r^2 sin(2b)<br /> 2<br /><br />where we have used the trigonometric identity 2sin(x)cos(x) = sin(2x).<br />Therefore, the area of the region CFD is<br /><br /> 1<br /> Area of CFD = b r^2 - --- r^2 sin(2b)<br /> 2<br /><br />Similarly we have<br /><br /> 1<br /> Area of CED = a R^2 - --- R^2 sin(2a)<br /> 2<br /><br />Now, the trick that Hippocrates saw was that we could eliminate the<br />transcendental terms b r^2 and a R^2 from the expression for the area<br />of the lune if we set those terms equal to each other. Thus, we<br />restrict ourselves to only those cases where<br /><br /> b r^2 = a R^2<br /><br />In these cases the area of the lune is simply<br /><br /> 1 1<br /> Area of lune = --- R^2 sin(2a) - --- r^2 sin(2b)<br /> 2 2<br /><br />Now, since we want to be able to construct this area from a unit<br />length (such as taking r=1) using only quadratic operations, the<br />length of R must be constructible, so we will require it to be of<br />the form<br /> R^2 = u r^2<br /><br />so that R = sqrt(u) r for some rational number u. If then follows<br />from the relation br^2 = aR^2 that<br /><br /> b = ua<br /><br />so we can make these substitutions into the expression for the lune<br />area to give<br /><br /> r^2 / \<br /> Area of lune = --- ( u sin(2a) - sin(2ua) )<br /> 2 \ /<br /><br />Of course, from the original diagram we can equate the vertical heights<br />to give the relation<br /><br /> r sin(b) = R sin(a)<br /><br />which implies<br /> __<br /> sin(ua) = /u sin(a) (1)<br /><br />Recalling the identities <br /><br /> sin(2x) = 2sin(x)cos(x) and cos(x)^2 = 1 - sin(x)^2<br /><br />we can rewrite the equation for the area of the lune entirely in terms<br />of sin(a), which we will abbreviate as "s".<br /><br /> / _______ _ ________ \<br /> Area of lune = s r^2 ( u /1 - s^2 - /u /1 - us^2 ) (2)<br /> \ /<br /><br />Therefore, we can "square the lune" (apologies to Debussey) by<br />Euclidean methods if we can determine s = sin(a) by solving nothing<br />more complicated than quadratics. It's not hard to see that equation<br />(1) can be solved for sin(a) by means of quadratics and square roots<br />only for certain values of the rational number u. To see this, recall<br />the well-known trigonometric identities for multiple angles<br /><br /> sin(2x) = 2sin(x)cos(x)<br /><br /> sin(3x) = 3sin(x) - 4sin(x)^3<br /><br /> sin(4x) = cos(x)[4sin(x) - 8sin(x)^3]<br /><br /> sin(5x) = 5sin(x) - 20sin(x)^3 + 16sin(x)^5<br /><br /> sin(6x) = cos(x)[6sin(x) - 32sin(x)^3 + 32sin(x)^5]<br /><br /> sin(7x) = 7sin(x) - 56sin(x)^3 + 112sin(x)^5 - 64sin(x)^7<br /><br />and so on. If we set u=2 in equation (1) (and again denote sin(a)<br />as simply "s") we have<br /> _______ _<br /> /1 - s^2 = /2<br /><br />and so s^2 = 1/2 and s = 1/sqrt(2). Substituting this into (2), and<br />setting r=1, gives the area A = 1. This was the first case found by<br />Hippocrates, and is shown below.<br /><br /> <br /><br />Notice that the area of the lune equals the area of the major triangle<br />to the left of the vertical line.<br /><br />Now consider what happens if we set u=3. In this case equation (1)<br />becomes<br /> _<br /> 3 - 4s^2 = /3<br /><br />and so we have s^2 = (3-sqrt(3))/4 and s = sqrt[3-sqrt(3)]/2.<br />Substituting into equation (2) gives the area of the lune<br /><br /> _ ______ _____________ _<br /> 1 | / _ / _ |<br /> A = --- | / 18 /3 - / 42 /3 - 72 |<br /> 4 |_ / / _|<br /><br /><br /> = 1.179959679570986...<br /><br />This lune is shown in the figure below.<br /><br /> <br /><br />For the third squarable lune, consider what happens if we set u=3/2.<br />In this case we can define the half-angle w = a/2 so we have a=2w and<br />ua = 3w. Equation (1) then becomes<br /> ___<br /> sin(3w) = /3/2 sin(2w)<br /><br />We can now use the trig multiple angle formulas to expand this into<br />an equation in terms of S = sin(w) as follows<br /> ____ _________<br /> 3 - 4S^2 = 2 / 3/2 / 1 - S^2<br /><br />Squaring both sides and simplifying gives a quadratic in S^2<br /><br /> 16 S^4 - 18 S^2 + 3 = 0<br /><br />which gives S^2 = [9 - sqrt(33)]/16. (The other root leads to a<br />complex result.) This is sin(w)^2, which equals sin(2a)^2, so we<br />need to convert this to an expression for sin(a) using the half-angle<br />formula, which gives sin(a) = sqrt[30 + 2sqrt(33)] / 8, and so we<br />have the angle a = 0.935929456... On this basis the area of the<br />lune is<br /> <br /> / _________ ___________ \<br /> 1 / / __ _ / __ \<br /> A = --- ( 3 / 111 + /33 - /3 / 93 - 13 /33 )<br /> 32 \ / --------- / ----------- /<br /> \ / 2 / 2 /<br /><br /><br /> = 0.552446605462519...<br /><br />This lune is illustrated below.<br /><br /> <br /><br />Apparently the above cases were the only ones known in antiquity. The<br />next case for which equation (1) reduces to a quadratic is with u=5,<br />which leads to<br /><br /> 16s^4 - 20s^2 + [5 - sqrt(5)] = 0<br /><br />where "s" again denotes sin(a). Solving this for s^2 gives<br /> __________<br /> / _<br /> 5 +- / 5 + 4 /5<br /> s^2 = ------------------<br /> 8<br /><br />The root with the "+" sign leads to a complex angle, but with the "-"<br />sign we get a = 0.409090011..., which produces the squareable lune<br />shown below<br /><br /> <br /><br />The only other value of u for which equation (1) reduces to a<br />quadratic equation is u = 5/3. In this case we write the equation<br />in terms of w = a/3, so letting S denote sin(w) we have<br /><br /> 5 - 30S^2 + 16S^4 = sqrt(5/3) [ 3 - 4S^2]<br /><br />This is a quadratic in S^2, so we can solve it to give<br /> _______________<br /> __ / ____<br /> 15 - /15 +- / 60 + 6/ 15<br /> S^2 = --------------------------------<br /> 24<br /><br />Taking 3 times the inverse sine of the square root of these quantities<br />gives the two possible values of the angle, of which only the first<br />is relavant, so we have the angle<br /><br /> a = 0.87932759...<br /><br />This last squarable lune is illustrated below.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-88111766356713127442008-11-19T08:20:00.001-08:002008-12-23T01:17:25.196-08:00Heron's Formula and Brahmagupta's GeneralizationLet a,b,c be the sides of a triangle, and let A be the area of the<br />triangle. Heron's formula states that A^2 = s(s-a)(s-b)(s-c), <br />where s = (a+b+c)/2. The actual origin of this formula is somewhat<br />obscure historically, and it may well have been known for centuries<br />prior to Heron. For example, some people think it was known to<br />Archimedes. However, the first definite reference we have to this<br />formula is Heron's. His proof of this result is extremely circuitious,<br />and it seems clear that it must have been found by an entirely different<br />thought process, and then "dressed up" in the usual synthetic form<br />that the classical Greeks preferred for their presentations.<br /><br />Here's a much more straightforward derivation. Consider the general<br />triangle with edge lengths a,b,c shown below<br /><br /> <br /><br />We have a = u+v, b^2 = h^2+u^2, c^2 = h^2+v^2. Subtracting the<br />second from the third gives u^2-v^2 = b^2-c^2. Dividing both sides<br />by a = u+v, we have u-v = (b^2-c^2)/a. Adding u+v = a to both<br />sides and solving for u gives<br /><br /> a^2 + b^2 - c^2<br /> u = -----------------<br /> 2a<br /><br />Taking h = sqrt(b^2-u^2) we have<br /><br /> __________________________________<br /> 1 | / \ 2 / a^2 + b^2 - c^2 \ 2<br /> A = ah/2 = --- | ( ab ) - ( ----------------- ) (1)<br /> 2 \| \ / \ 2 /<br /><br />which is equivalent to Heron's formula. Factoring out 1/4, this gives<br />three different ways of expressing (2ab)^2 - (a^2+b^2-c^2)^2 as a<br />difference of two squares. Equivalently, it gives three different<br />factorizations of 16A^2, each of the form<br /><br /> 16A^2 = [(a+b)^2 - c^2] [c^2 - (a-b)^2] (2)<br /><br />Factoring each of these terms gives the explicitly symmetrical form<br /><br /> 16A^2 = (a+b+c)(a+b-c)(c-a+b)(c+a-b) (3)<br /><br />so if we define s=(a+b+c)/2 we can write equation (1) as<br /> ________________<br /> A = /s(s-a)(s-b)(s-c) (4)<br /><br />which is the area formula as given by Heron.<br /><br />For an alternative derivation see Heron's Formula For Tetrahedrons.<br /><br />Incidentally, if we factor ab out of the radical in equation (1) we<br />get<br /> ____________________________<br /> ab | / a^2 + b^2 - c^2 \ 2<br /> A = ah/2 = --- | 1 - ( ----------------- ) (5)<br /> 2 \| \ 2ab /<br /><br />Notice that if we take either the edge "a" or "b" as the base of the<br />triangle, then the height is sin(q) where q is the angle between "a"<br />and "b", and of course the area of half the altitude times the base<br />(which is easily seen by considering the parallelogram), so we have<br />A = (ab/2) sin(q), which implies that the radical in (5) equals the<br />sine of the angle between "a" and "b". Furthermore, it implies that<br />the cosine is given by the well-known formula<br /> <br /> / a^2 + b^2 - c^2 \<br /> cos(q) = ( ----------------- )<br /> \ 2ab /<br /><br />[By the way, permutations of {a,b,c} = {3,5,7} in equation (2) give<br />the three factorizations 675 = (15)(45) = (9)(75) = (5)(135), which<br />leaves out (1)(675), (3)(225), and (25)(27). Is there an expression<br />in a,b,c that gives these three factorizations under permutation?]<br /><br />One of the most beautiful things about Heron's formula is the<br />generalization discovered by the Hindu mathematician Brahmagupta<br />around 620 AD. He noted that we have a symmetrical product of four<br />factors inside the square root of equation (4), consisting of twice<br />the quantities<br /><br /> a+b+c a+b-c a-b+c -a+b+c<br /><br />In a sense we can "full out" the symmetry, making each of the four<br />factors symmetrical with the others, by imagining a fourth "side"<br />of length d=0 being subtracted from the first factor and added to<br />the remaining three, so we have<br /><br /> a+b+c-d a+b-c+d a-b+c+d -a+b+c+d<br /><br />Obviously with d=0 this is identical to the previous set of factors,<br />but it has greater formal symmetry, so it seems as if the quantity<br /><br /> 1 _____________________________________<br /> --- /(a+b+c-d)(a+b-c+d)(a-b+c+d)(-a+b+c+d)<br /> 4<br /><br />MUST represent... something meaningful. Indeed it does. This is the<br />area of a quadrilateral with sides a,b,c,d inscribed in a circle, i.e.,<br />a cyclic quadrilateral. Naturally every triangle is cyclic, meaning<br />that it can be inscribed in a circle, and a triangle can be regarded<br />as a quadrilateral with one of its four edge lengths set equal to zero.<br />Brahmagupta didn't actually give a formal proof of this result, and<br />in fact the surviving copies of his statement of this proposition<br />don't mention the fact that it applies only to cyclic quadrilaterals.<br />It's tempting to think that Brahmagupta might have just imagined the<br />equation based on its formal symmetry.<br /><br />Incidentally, the formula for the area of an arbitrary quadrilateral<br />is<br /><br /> 1 ________________________________________________________<br /> --- /(a+b+c-d)(a+b-c+d)(a-b+c+d)(-a+b+c+d) - 16 abcd cos(q)^2<br /> 4<br /><br />where q is half the sum of two opposite angles. For a cyclic<br />quadrilateral the each pair of opposite angles sums to pi, so it<br />reduces to Brahmagupta's formula.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-61800412393806050522008-11-19T08:19:00.001-08:002008-12-23T01:17:25.196-08:00Heron's Formula For TetrahedronsThe article Heron's Formula For Triangle Area gives a very direct<br />derivation of Heron's formula based on Pythagoras's Theorem for right<br />triangles. However, we might also observe that Heron's formula is<br />essentially equivalent to Pythagoras' Theorem for right tetrahedrons.<br />If B,C,D denote the areas of the three orthogonal faces of a right<br />tetrahedron, and A denotes the area of the "hypotenuse face", then<br />it's easy to show that<br /><br /> A^2 = B^2 + C^2 + D^2 (1)<br /><br />This is essentially Heron's formula. Note that if a,b,c denote the<br />three orthogonal edges of the tetrahedron, then the areas B,C,D are<br />simply ab/2, ac/2, and bc/2. Furthermore, the edges of the hypotenuse<br />face d,e,f are directly related to a,b,c according to<br /><br /> d^2 = a^2 + b^2<br /> e^2 = a^2 + c^2 (2)<br /> f^2 = b^2 + c^2<br /><br />so we can express the areas B,C,D in equation (1) in terms of d^2,<br />e^2, and f^2 to give Heron's formula explicitly.<br /><br />Incidentally, it might be argued that this derivation does not<br />apply to obtuse triangles, because the "hypotenuse face" of a right<br />tetrahedron is necessarily acute (i.e., each of its angles must<br />be less than 90 degrees). However, the truth is that ANY triangle<br />can be the hypotenuse face of a right tetrahedron, provided the<br />orthogonal edge lengths and areas are allowed to be imaginary.<br /><br />For ANY values of d,e,f we can solve equations (2) for the orthogonal<br />edges of the right tetrahedron whose hypotenuse is the triangle with<br />the edges lengths d, e, f. This gives<br /><br /> a^2 = (d^2 - e^2 + f^2)/2<br /> b^2 = (d^2 + e^2 - f^2)/2<br /> c^2 = (-d^2 + e^2 + f^2)/2<br /><br />For example, suppose we want the area of a triangle with edge lengths<br />8, 5, and 5, which is an obtuse triangle. Substituting these into<br />the above equations gives<br /><br /> a = sqrt(32) b = sqrt(32) c = sqrt(-7)<br /><br />so the "c" leg has imaginary length. Consequently, two of the three<br />orthogonal faces (those given by ac/2 and bc/2) are also imaginary.<br />However, these areas only appear _squared_ in the Pythagorean formula<br />for right tetrahedrons, so we're guaranteed to get a real area for<br />the hypotenuse face. As Hadamard said, "The shortest path to any<br />truth involving real quantities often passes through the complex<br />plane".<br /><br />I honestly wouldn't be surprised if the ancient Greeks were aware of<br />the connection between the generalized Pythagorean theorem and Heron's<br />formula, but refrained from presenting it in that form because of<br />difficulties with interpreting the obtuse case. Recall that Descartes,<br />for one, believed the ancient Greeks had discovered most of their<br />theorems analytically by means of coordinate geometry and algebra, but<br />then concealed their methods, presenting them in synthetic form, so as<br />to make the results seem more daunting and impressive to the uninitiated.<br />It has always been doubtful that Heron's formula was discovered via<br />the throught process of Heron's proof, which is absurdly circuitous.<br />In any case, this is a nice example of how imaginary numbers can arise<br />naturally in dealing with questions of purely real quantities.<br /><br />As for higher dimensional simplexes, there is no complete generalization<br />of Heron's formula giving the volume of a general tetrahedron in terms<br />of the areas of its faces, because the face areas don't uniquely determine<br />the volume (in contrast to the case of triangles, where the three<br />edge lengths determine the area). However, it IS possible to derive<br />a "Heron's formula" for tetrahedrons if we restrict ourselves to just<br />those that would fit as the "hypotenuse face" of a right 4D solid.<br />(Notice that EVERY triangle is the face of a right tetrahedron, which<br />explains why Heron's formula is complete for triangles).<br /><br />To review, remember that Heron's formula for triangles is essentially<br />equivalent to Pythagoras' Theorem for right tetrahedrons. Let's let<br />A_xyo, A_xoz, and A_oyz denote the areas of the three orthogonal faces<br />of a right tetrahedron, and A_xyz denote the area of the "hypotenuse<br />face", so we have<br /><br /> (A_xyz)^2 = (A_xyo)^2 + (A_xoz)^2 + (A_oyz)^2 (3)<br /><br />Now if we let L_x, L_y, L_z denote the three orthogonal edge lengths<br />of the tetrahedron, then the areas of its orthogonal faces are simply<br /><br /> A_xyo = (L_x)(L_y)/2<br /> A_xoz = (L_x)(L_z)/2<br /> A_oyz = (L_y)(L_z)/2<br /><br />and so equation (3) can be re-written in the form<br /><br />4(A_xyz)^2 = ((L_x)(L_y))^2 + ((L_x)(L_z))^2 + ((L_y)(L_z))^2 (4)<br /><br />Furthermore, the three edges L1, L2, L3 of the hypotenuse face are<br />directly related to L_x, L_y, L_z by the 2D Pythagorean theorem<br /><br /> L1^2 = (L_x)^2 + (L_y)^2<br /> L2^2 = (L_x)^2 + (L_z)^2 (5)<br /> L3^2 = (L_y)^2 + (L_z)^2<br /><br />Equations (5) are three linear equations in the three squared edge<br />lengths, so we can solve for these squared lengths in terms of L1,<br />L2, and L3, and then substitute these into equation (4) to give<br />the ordinary Heron's formula for triangles, as before.<br /><br />Now, we can do the same thing for tetrahedrons based on the<br />generalized Pythagorean theorem for volumes of *right* 4D solids<br /><br />(V_wxyz)^2 = (V_wxyo)^2 + (V_wxoz)^2 + (V_woyz)^2 + (V_oxyz)^2 (3')<br /><br />If we let L_w, L_x, L_y, L_z, denote the orthogonal edge lengths of the<br />4D solid, then the volumes of the four orthogonal "faces" are simply<br /><br /> V_wxyo = (L_w)(L_x)(L_y)/6<br /> V_wxoz = (L_w)(L_x)(L_z)/6<br /> V_woyz = (L_w)(L_y)(L_z)/6<br /> V_oxyz = (L_x)(L_y)(L_z)/6<br /><br />so equation (3') can be rewritten as<br /><br />36(V_wxyz)^2 = ((L_w)(L_x)(L_y))^2 + ((L_w)(L_x)(L_z))^2<br /><br /> + ((L_w)(L_y)(L_z))^2 + ((L_x)(L_y)(L_z))^2 (4')<br /><br />Furthermore, the four areas A1, A2, A3, A4 of the hypotenuse "face" are<br />directly related to L_x, L_y, L_z by the 3D Pythagorean theorem (4)<br /><br />4(A1)^2 = ((L_w)(L_x))^2 + ((L_w)(L_y))^2 + ((L_x)(L_y))^2<br />4(A2)^2 = ((L_w)(L_x))^2 + ((L_w)(L_z))^2 + ((L_x)(L_z))^2 (5')<br />4(A3)^2 = ((L_w)(L_y))^2 + ((L_w)(L_z))^2 + ((L_y)(L_z))^2<br />4(A4)^2 = ((L_x)(L_y))^2 + ((L_x)(L_z))^2 + ((L_y)(L_z))^2<br /><br />Thus, given the four face areas A1, A2, A3, A4, we have four equations<br />in the four unknowns L_2, L_x, L_y, L_z, so we can solve for these<br />values and then compute the volume of the tetrahedron using (4').<br /><br />At this point people usually turn away from this approach, for two<br />reasons. First, everything we're doing is restricted to the "special"<br />tetrahedrons that can serve as the hypotenuse of a "right" 4D simplex,<br />so we're certainly not going to end up with a general formula<br />applicable to every tetrahedron (as is clear from the fact that we<br />have only four independent edge lengths here, whereas the general<br />tetrahedron has six). General formulas giving the volume in terms of<br />the edge lengths ARE available such as the one give by the Italian<br />painter Piero della Francesca. Of course, all such formulae can<br />be traced back to the well-known determinant expression for volumes.<br /><br />The second reason that people usually give up on equations (5') is<br />that they are somewhat messy to solve, since they are non-linear in<br />the lengths. Still, we might decide to press on anyway. It turns<br />out (after extensive algebraic manipulation) that we can reduce (5')<br />to a single quartic in the square of any of the four edge lengths L_w,<br />L_x, L_y, or L_z. Arbitrarily selecting L_y, and letting A,B,C,D<br />denote 4 times the squares of the face areas (i.e., the left hand<br />sides of equations (5')), we can express the quartic in x = (L_y)^2<br />with coefficients that are functions of B and the elementary symmetric<br />polynomials of A,C,D<br /><br /> r = A+C+D s = AC+AD+CD t = ACD<br /><br />In these terms the quartic for x = (L_y)^2 is<br /><br /> [12B] x^4<br /> + [3r^2 - 12s + 14Br - B^2] x^3<br /> + [2B(r^2 + 6s) - rB^2 - r^3 + 4rs - 36t] x^2<br /> + [2B(rs + 6t) - sB^2 + 4s^2 - sr^2 - 12rt] x<br /> - [t(r-B)^2] = 0<br /><br />Of course, the analagous quartics can be given for (L_w)^2, (L_x)^2,<br />and (L_z)^2, but once we have any one of them we can more easily compute<br />the others. For example, given L_y we can compute L_x from the relation<br /> ___________________________<br /> / ((L_y)^2 + A)((L_y)^2 + D)<br /> L_x = -L_y +- / ---------------------------<br /> \/ ((L_y)^2 + C)<br /><br />and the values of L_w and L_z follow easily, allowing us to compute<br />the volume using equation (4'). It would be nice if we could express<br />the volume as an explicit function of the face areas, but I don't<br />know if such a formula exists.<br /><br />In the preceding discussion we developed a tetrahedral version of<br />Heron's formula for a restricted class of tetrahedra, namely those<br />that can serve as the hypotenuse of a "right" 4D simplex, but there<br />are other special classes of tetrahedra that possess interesting<br />volume formulas. The one that gives the closest analogue to Heron's<br />formula is the class of tetrahedra whose opposite edges lengths<br />are equal. Thus there are only three independent edge lengths, and<br />each face of the tetrahedron is identical. Letting (a,f), (b,e), and<br />(c,d) denote the pairs of opposite edge lengths, we can set a=f, b=e,<br />and c=d in the basic determinant expression for the volume, or<br />equivalently in Piero della Francesca's formula, and we find that<br />the resulting expression for the squared volume factors as<br /><br /> 72 V^2 = (-a^2 + b^2 + c^2)(a^2 - b^2 + c^2)(a^2 + b^2 - c^2)<br /><br />which is certainly reminiscent of Heron's formula for the area of<br />each face<br /><br /> 16 A^2 = (a+b+c)(-a+b+c)(a-b+c)(a+b-c)<br /><br />This also shows that if each face is an identical right triangle, the<br />volume is zero, as it must be, since four such triangles connected<br />by their edges to give a tetrahedron necessarily all lie flat in the<br />same plane:<br /> ________<br /> |\ /|<br /> | \ / |<br /> | \ / |<br /> | \/ |<br /> | /\ |<br /> | / \ |<br /> | / \ |<br /> |/______\|<br /><br />Obviously we can construct a regular tetrahedron with equilateral<br />triangles of the same area as these right triangles, and the volume<br />is V = a^3 / sqrt(72), which illustrates the fact that the face<br />areas of a tetrahedron do not in general determine it's volume.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-61390291957180948412008-11-19T08:18:00.001-08:002008-12-23T01:17:25.196-08:00TriangleGiven an arbitrary triangle ABC, let D be the foot of the perpendicular<br />from A to BC, let E be the foot of the perpendicular from D to AC, and<br />let F be a point on the line DE, as illustrated below<br /><br /> <br /><br />Florin Pirvanescu challenged the readers of Mathematics Magazine in<br />June 1991 to prove that AF is perpendicular to BE if and only if<br />FE/FD = BD/DC. Several proofs have appeared, based on synthetic,<br />projective, and vector methods. These proofs are all fairly elaborate,<br />but there is actually a very simple elementary proof, which is a nice<br />example of "thinking outside the box".<br /><br />Let G be the foot of the perpendicular from B to DE, as shown below.<br /><br /> <br /><br />Clearly BDG ~ DAE and DGE ~ DBC, so we have BG/DG = DE/AE and<br />EG/DG = CB/DB. Also, AEF ~ EGB, giving EG/BG = AE/FE, if and only<br />if AF is perpendicular to BE. Thus we have<br /><br /> /BG\ /EG\ /DE\ /AE\<br /> ( -- )( -- ) = ( -- )( -- )<br /> \DG/ \BG/ \AE/ \FE/<br /><br />which implies DE/FE = EG/DG = CB/DB and so FED ~ DBC if and only if<br />AF is perpendicular to BE.<br /><br />Double Equations from Triangles in Squares<br />Given the square [1234] in the figure below, is it possible for both<br />of the inscribed right triangles [125] and [345] to have integer<br />(or rational) edge lengths?<br /><br /> <br /><br />If we let "a" denote the length of the edge [12] and "b" denote the<br />intermediate length [25], then obviously the condition for both<br />triangles to be Pythagorean is that both of the equations<br /><br /> a^2 + b^2 = f^2 a^2 + (a-b)^2 = h^2 (*)<br /><br />are satisfied, where f and h are integers representing the lengths<br />of the "hypotenuses" [15] and [45] respectively.<br /><br />Now suppose that instead of drawing the line from [5] to [4], we<br />draw a line from [5] to [6] so that the angle (156) is a right angle,<br />and then we draw the line [6,1]. Thus the original square [1234] is<br />partitioned into four right triangles. Is it possible for all four of<br />these to be Pythagorean triangles? Interestingly, the necessary and<br />sufficient condition for this is the same as for the previous case,<br />i.e., a (non-trivial) integer solution to the double equation (*).<br /><br />To show this, let's assign letters to the segment lengths as follows:<br /><br /> [12] = a [25] = b [53] = c<br /> [36] = d [46] = e [15] = f<br /> [16] = g [45] = h [56] = j<br /><br />By similar triangles we have a/c = b/d = f/j. Also, we can immediately<br />express c,d,e in terms of a,b as follows<br /><br /> c = a-b<br /> d = bc/a = b(a-b)/a<br /> e = a-d = a - b(a-b)/a<br /><br />Now, in order for all four of the right triangles partitioning the<br />square to be rational (which can easily be converted to integers),<br />we must have in addition to a^2 + b^2 = f^2 the equations<br /><br /> j^2 = c^2 + d^2 g^2 = a^2 + e^2<br /><br />However, the triangle with edge lengths "cdj" is similar to "abf",<br />so if the "abf" triangle is rational, then it follows that the "cdj"<br />triangle is also rational. Specifically we have j^2 = (cf/a)^2.<br />Hence the only real requirement beyond the "abf" triangle being<br />rational is that the "aeg" triangle be rational, which is true if<br />and only if<br /><br /> / b(a-b) \ 2 a^4 + (a^2 - ab + b^2)^2<br /> a^2 + e^2 = a^2 + ( a - ------ ) = ------------------------<br /> \ a / a^2<br /><br />is a rational square. Obviously the denominator is a square, so we<br />need only consider the numerator, which factors as<br /><br /> a^4 + (a^2 - ab + b^2)^2 = [a^2 + b^2][a^2 + (a-b)^2]<br /><br />The first factor on the right side is already known to be a rational<br />square, since we have required that "abf" is a rational triangle.<br />Therefore, the other factor must also be a rational square, and so<br />we arrive at the same double equation as (*) above.<br /><br />Of course, the equivalence of the rationality conditions for triangles<br />[345] and [156] was to be expected, because these two triangles are<br />obviously similar (noting that f/j=a/c) and have at least one rational<br />edge assuming that [125] is rational. As a result, we can construct<br />a new square [1587] and we find that point 7 lies along the line<br />{364}. Needless to say we have [678] similar to [512], and [679] is<br />similar to [345] and [516].<br /><br />But none of this answers the original question, which is whether<br />such constructions are actually possible, i.e., whether there is<br />an integer solution of the double equation<br /><br /> x^2 + y^2 = m^2 x^2 + (x-y)^2 = n^2<br /><br />The question of whether two quadratic forms in two variables has<br />solutions, and if so, whether it has infinitely many, has been studied<br />for many years, going back to Diophantus, Bachet, Fermat, Euler, and<br />so on. Notice that the right-hand equation can also be written in<br />the form 2x^2 - 2xy + y^2 = n^2. Many different techniques have<br />been developed to tackle this kind of problem, but it still is not<br />completely solved for arbitrary pairs of quadratic forms.<br /><br />To tackle this particular pair of equations, we first note that any<br />common factor in x and y can be divided out of both equations, so we<br />can assume that both are primitive Pythagorean triples. From this it<br />follows that x and y have opposite parity, as do x and x-y, which<br />implies that x must be even and y must be odd. Consequently we have<br />coprime integers A,B with opposite parity, and coprime integers C,D<br />with opposite parity, such that<br /><br /> x = 2AB x = 2CD<br /> y = A^2 - B^2 (x-y) = C^2 - D^2<br /> m = A^2 + B^2 n = C^2 + D^2<br /><br />This shows that AB = CD, so this product must have four pairwise<br />coprime factors r,s,R,S (precisely one of which is even) such that<br /><br /> A=rs B=RS C=rR D=sS<br /><br />Adding the previous expressions for y and x-y gives<br /><br /> x = A^2 - B^2 + C^2 - D^2<br /><br /> = (rs)^2 - (RS)^2 + (rR)^2 - (sS)^2<br /><br /> = (r^2 - S^2)(s^2 + R^2)<br /><br />Also, since x = 2AB = 2CD = 2rsRS, we have<br /><br /> (r^2 - S^2)(s^2 + R^2) = 2rsRS (1)<br /><br />Since r,s,R,S are pairwise coprime, we know that both r and S are<br />coprime to the first factor on the left, and both s and R are<br />coprime to the second factor. Hence, depending on which of the<br />two left hand factors is even (recalling that precisely one of<br />r,s,R,S is even) we have one of two cases:<br /><br />Case 1: Either r or S is even, and we have<br /><br /> r^2 - S^2 = Rs s^2 + R^2 = 2rS (2a,b)<br /><br />In this case we can factor the left hand equation to give<br /><br /> (r+S)(r-S) = Rs<br /><br />and since r,s,R,S are pairwise coprime we have pairwise coprime<br />integers u,v,U,V such that<br /><br /> uv = r+S UV = r-S uV = R vU = s<br /><br />Hence we have r = (uv+UV)/2 and S = (uv-UV)/2, and we can insert<br />these expressions into (2b) to give<br /><br /> (vU)^2 + (uV)^2 = 2(uv+UV)(uv-UV)<br /><br />Expanding the righthand product and re-arranging, we have<br /><br /> U^2 (v^2 + 2V^2) = u^2 (2v^2 - V^2) (3)<br /><br />and re-arranging differently gives the alternate form<br /><br /> V^2 (u^2 + 2U^2) = v^2 (2u^2 - U^2) (4)<br /><br />Since gcd(U,u)=1 we know that u^2 divides v^2 + 2V^2, and so on.<br />Hence equation (3) can be written as<br /><br /> (v^2 + 2V^2) (2v^2 - V^2)<br /> ------------ = ------------ = M<br /> u^2 U^2<br /><br />for some positive integer M. Likewise equation (4) can be written<br />in the form<br /><br /> (u^2 + 2U^2) (2u^2 - U^2)<br /> ------------ = ------------ = N<br /> v^2 V^2<br /><br />for some positive integer N. Consequently we have the equivalent<br />pairs of equations<br /><br /> v^2 + 2V^2 = Mu^2 2v^2 - V^2 = MU^2 (5a,b)<br /><br /> u^2 + 2U^2 = Nv^2 2u^2 - U^2 = NV^2 (6a,b)<br /><br />Multiplying (5a) by N and making the substitutions for Nv^2 and<br />NV^2 from equations (6) gives<br /><br /> MNu^2 = Nv^2 + 2(NV^2) = (u^2 + 2U^2) + 2(2u^2 - U^2) = 5u^2<br /><br />This shows that MN = 5 for positive integers M,N, so either M=1,N=5<br />or else M=5,N=1. Both of these lead to the same reciprocal pair of<br />quadratic forms (up to some permutation of the variables)<br /><br /> v^2 + 2V^2 = u^2 2v^2 - V^2 = U^2<br /><br /><br />Case 2: Either R or s is even, and we have<br /><br /> r^2 - S^2 = 2Rs s^2 + R^2 = rS (7a,b)<br /><br />In this case the left hand side is even, as is Rs, so we can write<br /><br /> r+S r-S R<br /> --- --- = - s<br /> 2 2 2<br /><br />assuming R is even. These factors are all coprime, so there are<br />pairwise coprime integers u,v,U,V such that<br /><br /> uv = (r+S)/2 UV = (r-S)/2 uV = R/2 Uv = s<br /><br />This implies r = uv+UV and S = uv-UV. Inserting these into (7b)<br />gives<br /> (Uv)^2 + 4(uV)^2 = (uv+UV)(uv-UV)<br /><br />Expanding and re-arranging gives<br /><br /> U^2 (v^2 + V^2) = u^2 (v^2 - 4V^2)<br /><br />and<br /> V^2 (4u^2 + U^2) = v^2 (u^2 - U^2)<br /><br />Proceding in the same way as in Case 1, we find that this leads to<br />a pair of equations of the form<br /><br /> v^2 + V^2 = u^2 v^2 - 4V^2 = U^2<br /><br />In this case we see the question is equivalent to asking whether -4<br />is a "concordant number", defined as an integer N such that x^2 + y^2<br />and x^2 + Ny^2 can both be squares simultaneously. This is discussed<br />at length in the note Concordant Forms, where a proof is<br />given that a large class of positive prime values of N are not<br />concordant.<br /><br />A different approach is to cast the problem in the form of an elliptic<br />curve. Returning to equation (1)<br /><br /> (r^2 - S^2)(s^2 + R^2) = 2rsRS<br /><br />we see that the first factor on the left can be divided by rS and the<br />second factor by Rs to give<br /><br /> [r/S - S/r][s/R + R/s] = 2<br /><br />Thus we have rational numbers X=r/S and Y=R/s such that<br /><br /> / 1 \ / 1 \<br /> ( X - --- )( Y + --- ) = 2<br /> \ X / \ Y /<br /><br />Multiplying through by XY gives<br /><br /> (X^2 - 1)(Y^2 + 1) - 2XY = 0<br /><br />If we define the new variable Z such that X = (Z+Y)/(Z-Y), then Z<br />is rational if X and Y are rational (and of course X is rational if<br />Z and Y are rational). Notice that if Y=0 then X=1 for ANY value of<br />Z, and this is a solution of the equation. Substituting for X gives<br /><br /> 2Y(2ZY^2 + 2Z - Z^2 + Y^2)<br /> -------------------------- = 0<br /> (Z-Y)^2<br /><br />Setting aside the trivial solution at Y=0, and assuming Y is not equal<br />to Z (which corresponds to infinite X) we are left with<br /><br /> 2ZY^2 + 2Z - Z^2 + Y^2 = 0<br /><br />which we can solve for Y^2 to give<br /><br /> Z(Z-2)<br /> Y^2 = ------<br /> (2Z+1)<br /><br />If we now define the variable W by the bi-rational form Y = W/(2Z+1)<br />and substitute for Y into the above expression, we get the elliptic<br />curve<br /> W^2 = Z(Z-2)(2Z+1)<br /><br />This is nearly identical to the elliptic curve that arises when<br />proving that there cannot exist four squares in arithmetic progression.<br />Only the sign in the second factor is different. As discussed in<br />Weil's historical review of "Number Theory", essentially this same<br />problem was treated by both Euler and Fermat.<br /><br />A plot of the real part of the elliptic curve y^2 = x(x-2)(2x+1) is<br />shown below.<br /><br /> <br /><br />There are obviously at least three rational points on this curve,<br />given by (x,y) = (0,0), (2,0), and (-1/2,0). Notice that these three<br />rational points lie along the "horizontal" axis of symmetry of the<br />curve. Any straight line passing through the closed loop on the<br />left and striking the open branch of the curve on the right has<br />three real points of intersection, and obviously if two of those<br />points are rational then the third must be also. This shows how,<br />if we are given any two rational points, we can generally construct<br />a third, simply by drawing a line through the two given points and<br />locating the remaining intersection point.<br /><br />For example, suppose the point (x1,y1) on the curve above is a rational<br />point. In that case we could draw the line through the two points<br />(-1/2,0) and (x1,y1) as shown, and then we would have a new rational<br />solution at the point (x2,y2). The equation of the line is<br /><br /> y1 y1<br /> y = -------- x + -------<br /> x1 + 1/2 2x1 + 1<br /><br />Squaring this and equating it with y^2 = x(x-2)(2x+1) gives a cubic<br />equation in x whose three roots are the x values of the three points<br />of intersection between the line and the elliptic curve. We already<br />know that two of these roots are x=-1/2 and x=x1, so we can easily<br />determine the third root and the corresponding value of y:<br /><br /> (y1)^2 2x2 + 1<br /> x2 = - ------------- y2 = y1 -------<br /> x1(2x1 + 1)^2 2x1 + 1<br /><br />Hence if x1 and y2 are both rational, then so are x2 and y2. Once we<br />have found this new rational point we can draw lines through it and<br />any previously found rational points to generate still more rational<br />solutions. Of course, in order to accomplish this we need first to<br />have one rational point off the axis of symmetry.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-64374191572172964642008-11-19T08:11:00.000-08:002008-12-23T01:17:25.196-08:00Mahatma GandhiGandhi emerged as a political leader in 1919. In 1893, he went to South Africa as the lawyer of a firm of Porbander Muslims and was deeply shocked by the disabilities of the Indians there. It is here that he first used his political weapon Satyagraha with which he achieved success. It may be useful to mention that the doctrine of passive resistance and Non-cooperation was preached by Sri Aurobindo in 1907. As Gandhi popularized the principle and technique of Satyagraha in Indian politics and its dominant role in the struggle for freedom, it is useful to know the general ideas and philosophy underlying it.<br /><br />1. The word Satyagraha consists of two words ie satya or truth and agraha or adherence. The word was originally coined in South Africa and was originally described by him as Passive Resistance. Later on he distinguished between the two i.e. satyagraha and passive resistance by saying “ The latter has been conceived as a weapon of the weak and does not exclude the use of physical force or violence for the purpose of gaining one’s end, whereas the former has been conceived as a weapon of the strongest and excludes the use of violence in any shape and form”.<br /><br />2. Satyagraha is the law of love, the way of love for all.<br /><br />3. Non-violence as expounded by Gandhi “When a person claims to be non-violent, he is expected not to be angry with one who has injured him. He will not wish him harm, he will not cause him physical hurt. He will put up with all injury to which he is subjected to by the wrong doer. Complete non-violence is complete absence of ill-will against all that lives”. Was Gandhi a saint!<br /><br />4. “Satyagraha eschews violence absolutely as a matter of principle, at all stages and forms. The idea is not to destroy or harass the opponent, but to convert him or win him over by sympathy, self-suffering and patience. It approaches the evildoer with love. The Satyagrahi has infinite trust in human nature and its inherent goodness”.<br /><br />5. “Non-violence, in its dynamic condition, means conscious suffering. It does not mean meek submission to the will of the evildoer, but it means the pitting one one’s whole soul against the will of the tyrant. Working under this law of our being, it is possible for a single individual to defy the whole might of an unjust empire, to save his honor and lay the foundation for that empire’s fall or regeneration.<br /><br />6. “I do not advice that where there is a choice between cowardice and violence, I would advice violence”.<br /><br />7. “The religion of non-violence is not merely meant for the rishis and saints. It is meant for the common people as well. Non-violence is the law of the brute. The rishis, who discovered the law of non-violence in the midst of violence, were greater geniuses than Newton”.<br /><br />8. “As a moral-not a physical weapon, it raises political warfare to a higher plane. Groups powerless in a political and military sense, can fall back upon it as their only weapon. It involves self-chosen suffering and humiliation for the resisters and thus demands in them unusual resources of self-mastery and strength of will”.<br /><br />Gandhi’s satyagraha did produce results e.g. the Champaran Agrarian Bill of 1917, two was with the millowners of Ahmedabad who lead a fast for higher pay to workers. Then there was the Satyagraha by the farmers of Kheda. While the Non-cooperation was called off and some gains lost, the mostly non-violent movement had two important gains. One was the willingness and ability of people to endure a remarkable degree of hardships inflicted by the govt. Two is that Non-Cooperation became a mass movement and the Congress a revolutionary organization.<br /><br />Did India get its independence because of Ahimsa? <br /><br />1. Quoting from the book Defending India “The British withdrawal from India was not, as if often asserted, an act of high statesmanship. A war-ravaged Britain was no longer in a position to hold India is bondage, its intelligent network had in any case been warning of a great disorder and public upheaval to follow if India did not gain independence, because British economic conditions in 1944-46 could not simply have permitted any continued occupation of India”.<br /><br />2. Throughout her rule, the Brits had used Indian soldiers to put down the protesting Indians. The formation of Netaji Bose’s Indian National Army proved beyond doubt to the Brits that they could no longer rely upon the Indian sepoys to maintain their hold over India. The universal sympathy when they were tried in the Red Fort gave a rude shock to the British, in as much as it proved that Indians of all shades put a premium on the disloyalty of Indian troops to their foreign masters and looked upon it as a sign of nationalism.<br /><br />3. A revolt took place in the section of the Royal Indian Navy in Bombay. It was later withdrawn due to the efforts of Patel. The Army and AirForce were affected but not of a serious nature. On 19/2/1946 PM Attlee announced that the govt of England would be sending three cabinet ministers to reach an agreement with the leaders of the Constitutional issue. What was the reason for the decision to despatch the Cabinet Mission is difficult to say but it may be noted that it came 3 days after the fall of Rangoon to the Japanese. Said Attlee on 15/3/1946 “that the time of nationalism was running very fast in India and that it was time for clear and definite action".<br /><br />4. The Japanese occupation of Burma brought the War to the door of India. Their warships seized the Andaman islands. Calcutta had air raids on December 1942. It created panic all over.<br /><br />Will Ahimsa succeeded every where?<br /><br />Quoting K Subrahmanyan from the book Defending India “It has been assumed that Gandhian prescriptions of non-violent mass action would be applicable, irrespective of context. Recently, after Attenborough’s film Gandhi, was released, questions have been raised whether Gandhian methods would have succeeded against Hitler, Stalin and the like. In strategic parlance, offense and defence are different. While the former aims at changing status quo, the latter attempts at to preserve it. In India, the Brits were on the defensive, while the freedom movement was on the offensive. While in the offensive mode the leader had the choice of strategy, including use of massive non-violent mobilization of people. If the state were to go on the offensive, the populace would not have been allowed non-violent mass mobilization. That is why non-violence could not have succeeded against Hitler, Stalin and Mao Zedong”.<br /><br />Was Gandhi’s policy of Ahimsa followed by all?<br /><br />1. Gandhi’s policy of non-violence was meant for the digestion of Hindus alone. For e.g. at the time of the Moplah Rebellion in Kerala that followed soon after the Khilfat Movement in 1920, Gandhi was nowhere close to the scene of action.<br /><br />2. Swami Shraddhananada, an important Arya Samaj leader, leading propagator of the Shuddhi Movement i.e. reconversion of Muslims to Hindus was murdered by a Muslim Abdul Rashid. Instead of criticizing that violent act , quoting Pattabhi Sitaramayya at the Gauhati Congress session of 1926 “Gandhi expounded what true religion was and explained the causes that led to the murder. Now you will perhaps understand why I have called Abdul Rashid a brother and I repeat it. I do not regard him as guilty of Swami’s murder. Guilty indeed are those who excited feelings of hatred against one another”.<br /><br />3. Jinnah’s Direct Action Day in 1946 saw Hindus being massacred in Bengal, in active connivance with Chief Minister Suhrawardy and the Brits. Yet during the partition riots in Bengal, Gandhi was sharing roof with the same Suhrawardy in one of Calcutta’s riot prone localities. Sardar Patel even rebuked him for living in a ruffians company.<br /><br />To be fair to Gandhi, when Hindus were killed in Noakali he went there to instill courage amongst the Hindus and tolerance amongst the Muslims. The point I am making is that non-violence was, is practiced more by Hindus than anyone else. On the other hand, the Muslims rarely follow this path. The Hindu was and is asked to be tolerant, forgive and forget.<br /><br />But it appears that Gandhi did not understand Muslim psyche. Quoting from Rajmohan Gandhi’s book on Sardar Patel, Gandhi to Patel, “You should try to learn Urdu. Patel replied, Sixty-seven years are over and this earthen vessel is near to cracking. It is very late to learn Urdu but I will try. All the same, your learning Urdu does not seem to have helped. The more you try to get close to them, the more they flee from you”.<br /><br />Appeasement, tolerance was the cornerstone of Gandhi’s Muslim policy. Starting with the Khilafat Movement, he made the Muslims realize that they were a different, Muslims first and then Indians. By not criticizing them when they took to violence he encouraged them further. Intransigent Muslim attitude lead to the Partition of India, thereby weakening it considerably. I must add that neither do I hold Gandhi or the Muslims wholly responsible for partition. There were others factors at play, which are beyond the scope of this article.<br /><br />Today, large sections of the English media churn out articles on the non-violent nature of Islam, how it preaches universal brotherhood. May be Islam does say so but when you recall the dastardly acts of its followers worldwide or the respect given to their women it makes you wonder what is the truth. After all every man is remembered by the legacy that he leaves behind.<br /><br />Comments - It would be incorrect to deride the role of Gandhi’s Satyagraha in India’s freedom movement but to say that it got India independence would be a travesty of truth. However, Gandhi’s one-sided Ahimsa has increased the Hindu-Muslim divide and lead to the weakening of pre and post-independent India.<br /><br />Impact of Ahimsa on independent India <br /><br />Somehow the Gandhian concept of Non-Violence i.e. do not get angry, wish him no harm or cause him no physical hurt to someone who has injured you has got so embedded into our minds that we either do not respond or do so inadequately inspite of grave provocation’s. In today’s world it is perceived to be weakness.<br /><br />Inadequate response even in the face of grave provocation does not appear to be because of people great respect for Gandhi or his definition of Ahimsa. It is pure selfishness. Trying to protect ones self interest in various circumstances. This is due to absence of true knowledge of Dharma. Such tendencies are because of weakness & insecurity. Can the average Indian learn about Dharma? He is taught The Merchant of Venice, Shakespeare, Romeo and Juliet in school. Kalidasa, Aryabhatta, who! The Holy Geeta, I am too young to read it.<br /><br />I share with you some examples on how Gandhi has influenced our thinking.<br /><br />1. Quoting Nehru from the book Defending India “Gandhi found himself unable to give up his fundamental principle of non-violence ever in regard to external war. He could not give up the faith of a lifetime. He wanted Congress to declare its adherence to the principle of non-violence even in free India. He realized that a government of free India was not likely to discard violence when questions of defence were concerned and to build up military, naval and air power. But he wanted if possible, for Congress at least to hold the banner of non-violence aloft and thus train the minds of the people and make them think increasingly in terms of a peaceful solution”.<br /><br />2. Quoting K. Subrahmanyam from Defending India “In order to develop an understanding of our policy in post-independence India, it is essential to look at the roots of that policy during the freedom struggle, since Gandhi was a fervent advocate of non-violence, Indian defence preparedness was not given the attention it deserved. There is also the view that Nehru was anti-militarist in his orientation and as, as an advocate of peace and non-alignment, neglected the role of military power in international relations”.<br /><br />3. Another issue was the Moral aspect. Quoting Nehru’s speech to the Constituent Assembly on 7/0/1948 from the book Defending India “When the question of Jammu and Kashmir invasion came up, I sought guidance from Gandhi, the apostle of non-violence who was not a suitable guide in military matters and he said so – but he undoubtedly always was a guide on moral issues. I nevertheless mention this matter merely to show how the moral aspect of this question has always troubled me”.<br /><br />4. Quoting from the book Defending India “ If Nehru bent backwards in accommodating China it was not out of fear of what it would do but of the common belief among gentlemen that human nature being essentially good, one sided favors done to our neighbors would fill them with gratitude and would cause them to reciprocate. This is a direct outcome of Nehru’s idealistic romanticism”.<br /><br />5. To be fair to Nehru he did make some references on the necessity of defence expenditure. Quoting Nehru’s speech in Lok Sabha in November 1962 he said “defence and development were two sides of the same coin”.<br /><br />6. Inspite of being warned by Patel, Nehru continued to ignore Chinese movements in Tibet and after its conquest he warned of potential troubles between India and China. Nehru however, chose to ignore these warnings and made Chinese appeasement the cornerstone of his policy ably followed by Atalji in his earlier dealings with Pakistan.<br /><br />7. Nehru believed that with India’s spiritualism and history of non-violence it could play a leading role in world’s affairs. He was a founder member of the Non-Aligned movement, introduced the mantra of peaceful coexistence. Yet what came out of it was the blunder of 1962.<br /><br />8. We ignored defence expenditure continuously in the 1950’s. Said noted Gandhian Acharya Kriplani speaking on the Defence Budget in the Lok Sabha in 1957 “The mounting expenses on the Army must be cut down. The followers of Gandhi and adherents of universal peace should not increase military expenditure”. These are idealistic words. Defence Minsiter Krishna Menon was a pacifists and not cut out for the role of a world leader. In 1947 there was plenty of equipment, which had deteriorated by 1962. He did not prepare or provide for the warfare at high altitude resulting in unnecessary lives being lost and the humiliation of 1962.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-53776330072307353882008-11-19T08:09:00.002-08:002008-12-23T01:17:25.196-08:00Samrat AshokaThe first major foreign invasion was by Alexander in 326 BC. The nature and extent of his raid on India are sometimes overstated. The adventure was brilliant but he never fought any of the great armies of Bharat. Neither was there a test between Greek and Indian military skills nor was his campaign a military success as it did not result in a permanent occupation of Punjab or leave an impact on the life of the people. What remained of the Greek occupation was wiped out by Chandragupta Maurya. But Alexander’s invasion promoted the political unification of India, smaller states got merged into bigger ones, paving the way for Chandragupta. The only permanent result of Alexander’s campaign was that it opened up communication between India and Greece. This was achieved at the cost of untold suffering inflicted upon India – massacre, rape, plunder on a scale without a precedent till then but repeated later by Timur, Nadir Shah.<br /><br />Chandragupta was succeeded by his son Bindusara (300 to 273 BC) followed by Ashoka (273 to 236 BC). A unique features of Ashoka’s rule that left a permanent record of his history in inscriptions engraved on natural rocks and pillars which continue to stand today as proof of India’s architectural / engineering skills.<br /><br />An able soldier he carried on a policy of conquest and aggression. He conquered Kalinga in the eight year after his coronation but the severity of the resistance put up and the resulting horrors are described in Rock Edict XIII. 1,50,000 captured, 1,00,000 slain and many times more died. Instead of gloating over his conquest, the war brought about a complete change in Ashoka.<br /><br />According to Buddhist tradition, Asoka was converted to Buddhism after the Kalinga war. In Rock Edict XIII, Asoka expresses genuine remorse for the sufferings caused by the war, he felt remorse on having conquered Kalinga. It is probably the only instance in world history where a victorious monarch is known to have given such expressions. He made two resolutions. One was to eschew all war in the future. “If anyone does him wrong the Beloved of the gods must bear all that can be borne”. Henceforth his policy would be one of conciliation towards all. The exhortation of good deeds was the foundation for his second resolution i.e. the inculcation of his Dharma (Dharma or law of Piety) not only among the people of his own dominions but all over the world. Asoka has up conquest through arms and replaced with conquest through Dharma.<br /><br />Asoka was attracted more by the ethical than the philosophical aspects of Buddhism and laid stress on the practical benevolent activities and thoughts inculcated by it. Then he entered and or lived in the Buddhist Sangha or monastery, took up missionary activities, the task of propagating Dharma, which is of such universal equality as to appeal to humanity at large. He set up a network of missions within India and abroad. To his credit, he did not ignore governance, in fact the new outlook made him very compassionate towards his subjects.<br /><br />Dharma – Asoka worked for the moral upliftment of people, insisted on family as the basis of morality, respect to be shown to elders and teachers. Thus the starting point of religious and moral life was purification of home, family and domestic life by the cultivation of relations with all concerned. Character, conduct and behavior counted more than ceremonies to him. Next religion was to extend from family to communities. The 12th Rock is an appeal for the toleration of all religious sects but also delivering a spirit of reverence for them. Above all, Asoka stood for Ahimsa to men and animals, which he preaches in all his edicts. Further he purified his national policy by proclaiming war as an unmitigated and absolute evil. He preached tolerance of all sects, schools of thought. Thus Asoka stood out as an apostle of Peace.<br /><br />A consequence of this passion for peace was that, unlike his illustrious grandfather’s scheme of establishing authority all over India, Asoka left unsubdued smaller and weaker people, states of India and established all states big or small on equal sovereignty.<br /><br />Asoka’s great innovation was the substitution of stone with wood and brick. He decorated the country with structures and artistic monuments. The Royal Palace of Pataliputra was recognized as the work of superhuman minds. He also improved upon the irrigation work started by Chandragupta Maurya.<br /><br />Post Ashoka – The history of his successors is shrouded in mystery. The reason being the empire was too large to be kept as one by unworthy successors. Asoka had too many sons, is likely that fought amongst themselves. It is however agreed that Brihadratha was the last king of the Maurya dynasty i.e. up to 187 BC. The progressive disintegration that followed Asoka’s rule is marked by several facts. According to Rajatarangini, Asoka’s son Jalauka became an independent ruler in Kashmir and conquered territory up to Kannauj. Another son Virasena set up at Gandhara. The disintegration of the Mauryan Empire was speeded up by the Yavana invasions, the final blow struck by the revolt of Pushyamitra, the commander-in-chief of Brihadratha.<br /><br />What are the reasons for the downfall of the Mauryan Empire? One view is that the humiliation of Brahmans led to a backlash and a revolution by a Brahman Pushyamitra. This logic seems slightly far-fetched. Another reason is the doctrine of Ahimsa. Since Ashoka eschewed all wars, naturally this reduced the military efficiency of his empire. However, considering the circumstances of those days, such a large empire was bound to break. There were other causes too, the spirit of local autonomy, oppressive rule and rebellious disposition of governors, palace intrigues and official treachery. Foreign invasion too. The repeated revolt by the province of Taxila, due to the opposition of local officials is one e.g. It is likely that weaknesses caused by internal dissension invited foreign aggression.<br /><br />There is no doubt that the moral ascendancy of Indian culture over parts of the world was thanks to Ashoka. As a country it has made many proud. It came albeit at a heavy price, a weak Central authority for which Bharat has had to pay a heavy price during the last two thousand years. All depends what you cherish. High moral values with massacre, rape, loot or political stability with protection of Dharma.<br /><br />Impact - Quote freedom fighter K M Munshi “But welfare states, which eschew armed coercion of recalcitrant elements are not known to survive. As soon as Asoka died, his Buddhist leanings and pacific policy evoked open resistance. Due to a lack of a vigorous military policy, the outlying provinces rose in revolt. The Greeks invaded India and advanced up to Ayodhya and Chitor. Further disintegration was halted when Pushyamitra (187 to 151 BC), took over what was left of the Empire. Dharma Vijaya was no longer to be achieved by abjuring war but by building military strength, politics became real. The Sungas vanished Greek invaders, were respected by foreign kings. They fostered a revival of art, literature and architecture. In Madhyadea, among the wise and intellectual, the ascetic look lost its attraction. Dharma was strengthened. The new wave of collective enthusiasm found its expression in a combative attitude against Buddhism in search of a fuller and richer life, in the cult of Karttikeya, the god of war, in the resurgence of the Bhagwata Cult, in the unchallenged supremacy of Vasudeva Krishna in the Hindu Pantheon”.<br /><br />Three main teachings of Asoka were “we must bear all that can be borne, policy of conciliation towards all and tolerate all religions”. These thoughts are divine but are they practical. For the last two thousand years Indians have borne more misery than any other nation in the world. Yet we have no respite. The rule today is that a person who suffers quietly should suffer more e.g. the Pandits of Jammu and Kashmir. Religious tolerance is amongst the best quality of Indian religions. It has allowed foreigners, Parsis, Jews to come and get absorbed in our country. Yet, this goodness is being misused by the Muslims and Christians to indulge in conversions and criticize our religion, culture in harsh terms.<br /><br />Has the policy of Conciliation brought peace in the Indian sub-continent? Our ex Prime Minster followed this policy in the form of Gujral Doctrine. Inspite of unilateral concessions to our neighbors Pakistan reason for existence is the destruction of India. Nepal has become a beehive of anti-India activities; a mere rumor is enough to start anti-India protests. The less said about the Bangladesh the better. We fought for their freedom, tolerate over 2 crore Bangladeshis in India, yet the recent killing of 16 Border Security Force soldiers in Meghalaya!<br /><br />I believe that in every experience there is learning. Asoka left an unparalleled example of the chaos that would reign in India when there was a weak central authority. Sardar Patel understood this and insisted on a strong center during his discussions with the British. But thereafter! Over 2,000 years have past, we continue to be influenced by Asoka’s concept of a welfare state.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-67003872558491359942008-11-19T08:09:00.001-08:002008-12-23T01:17:25.196-08:00JainismJain tradition speaks of 24 Tirthankaras of which, the first 22 seem to be mythical and have no historical foundation. The last two were Parsva and Mahavira. Parsva is believed to have lived some 250 yrs before Mahavir and is always referred as “beloved of men”. He believed in the eternity of matter as Mahavir did. The followers of Parsva preached that self-control results in the cessation of Karma and penance leads to annihilation. With this Mahavir agreed, as with the four vows enunciated by Parsva i.e. life should not be taken, no falsehood spoken, nothing should be received which is not freely given and non-attachment should be practiced. But there was a difference between the two sects, that Parsva followed allowed the use of a white garment by the monks while Mahavir forbade this. Hence the two sects titled Svetambara (white-clad) and Digambara (naked).<br /><br />Thus unlike Buddha, Mahavir was more of a reformer than a founder of a new religion. He became a monk at the age of 30, left home in the beginning of winter, 13 months later he abandoned his clothing and began to wander in the nude. He attributed life not only to plants and animals but also to earth and water, assumed the real cause of worldly misery to be Karma, engineered by indulgence by sensual pleasure, and the essential misery of life to be due to the endless cycle of life and birth. Mahavir added a few doctrines to this of Parsva; he taught five vows as against four referred to above, in all probability being chastity. He is credited with the systematic arrangement of its philosophical texts.<br /><br />Jainism showed a close affinity with the Samkhya system. It also developed a kind of logic, which cut at the root of all stable knowledge. It was called Syadvada or the theory of May Be. Jains had a theory of reality. Their logic was a subtle and disguised protest against the dogmatism of the Vedas, and not intended to deny reality. The world according to them was not altogether unknowable, only one must not be cocksure about one’s assertions. The world consisted of two categories the conscious (jiva) and the unconscious (ajiva).<br /><br />Jiva corresponds to what we call the soul. It suffers by its contact with matter and is born repeatedly and its highest endeavor is to free itself from bondage. And this salvation can be achieved by higher knowledge and meditation upon the great truth. According to some, jiva should be taken to mean life. Ajiva was equivalent to mean the universe minus the jivas. There is no God or Creator and man is the architect of his own destiny. By living an austere life of purity and virtue, he can escape the ills of life. The best life was the life of renunciation. It was the shortest way to salvation.<br /><br />Jainism is thus a moral code rather than a religion in the western sense of the term. It recognized no Supreme Being but there were a number of deified men who had been spiritually great. It did not encourage dogmatism. When all knowledge is only probable and relative, your opponent’s view as is as true as mine. The result of this spirit of accommodation was that Jainism has survived today while Buddhism vanished from India. The custom of idol worship may be traced back to the Mauryan-Sunga period. Mahavir in 468 BC.<br /><br />Impact - Buddhism and Jainism emphasized non-injury, compassion for others, suffering, austerity and non-violence. The most important teaching was that of non-violence. Not only had it influenced the minds of people of those times but even today, Indians of all hue and cry reiterate their love for non-violence inspite of the gravest of provocation by our enemies.<br /><br />Buddha introduced a unique institution of monasteries whereby young men and women gave up ordinary lives and moved into monasteries to achieve higher spiritual goals. Thus the services of these people were permanently lost to society and not available for protection of Dharma. These movements made asceticism popular across the country. These influences increased man’s ability to suffer oppression, made our hearts soft, weakened society and reduced the will to fight for the protection of Dharma. Since Buddha and Mahavir were divine souls and not rulers, it did not lead to an immediate loss of political control by the ruling class. <br /><br />After the second nuclear test i.e. Pokaran II, influenced by the principle of Ahimsa, a number of Indians were unhappy. What was the need? We are the land of Ahimsa. Amongst our neighbors China conducted its first test in 1964 and Pakistan is known to have achieved nuclear capability in 1987. Many believe that Operation Topac in Jammu and Kashmir was launched in 1989 i.e. after they had achieved nuclear deterrenceSumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-25987991786319819712008-11-19T08:08:00.001-08:002008-12-23T01:17:25.197-08:00BuddhismPre-Buddha - The Vedic Culture had, for its Central Idea, Rita, the Cosmic Order. The fundamentals flowing from it were Satya, accord between thought, word & deed, Yajna, the complete dedication of one’s cherished things to the Higher powers to fulfill Rita and Tapas, the sublimation of passions and instincts through discipline which brought self-mastery. Sage Kanada says “Dharma is that which gives prosperity in this life and liberation in the next”. There is no higher Dharma than truth. Action without Yajna is bondage says the Bhagwad Gita. Tapas came to comprise, as the Bhagwad Geeta has it, truth and non-violence.<br /><br />Long before the coming of Buddha, a central idea was becoming clear from the mass of incoherent urges, which went under the generic name of Dharma. Dharma is a way of life based on the eternal truths of life. Man was not a struggling worm but a self with a supraphysical destiny, which can be attained only by the mastery over the misery. This is possible by man being self-disciplined so as to raise the self above the flux of passing sense experience. Simply put, the mind must not be affected the joys and sorrows of life but carry on unaffected. The discipline implied relinquishment of the greed for life and broadening of the personal self into a universal self. The end of this discipline was variously aimed at self-realization (Siddhi), emancipation (Mukti), and freedom (Nirvana), enlightenment (Jnana), and bliss (Ananda) In short it meant absolute integration of the human personality freed from the limitations of attachment and fear.<br /><br />For such a planned social life stability was essential. It implied protection without slavery. Power was therefore conceived as moving and having its being within the framework of Dharma. Kingship was to be a religious trust. Rajadharma, Smriti and tradition were to be interpreted from the time to time to regulate life. The ambition of kings was controlled by a fundamental law, the basis of which were Smriti, Parishad, the Assembly of the learned. And as the country grew bigger a military overlord was necessary, Rajadhiraja or Chakravartin as the Protector of Dharma.<br /><br />The Mahabharata (about 1200 BC) that happened centuries before Buddha is all about the victory of Dharma over Adharma. Indian kings, all of whom accepted, the law of the Dharmasastras as unalienable, waged wars according to human rules. Whatever the provocation, the shrine, the Brahman, the cow were sacrosanct to them. Harassment of the civilian population was considered a serious lapse in the code of honor. The Kshatriyas had high regard for women ruled out their abduction as an incident of war.<br /><br />Essential Features of Buddhism - Gautama alias Siddharta was born at Lumbinivana in 563 BC. His father was the chief of the Sakya clan. Gautama lived a life of easy and luxury, got married, had a son called Rahula. After seeing four persons in four different stages, the idea of renunciation entered his mind. Some say that Siddharta believed that home life was full of hindrances and impurities so he decided to retire from the world. At the age of 29 he left home.<br /><br />At Vaisali he met Arada Kalama who espoused the Sankhya school of philosophy. Not satisfied with the teachings of this school he moved on to teacher Rudraka Ramaputra’s heritage. He went to Uruvela where he became Buddha, the Enlightened One. After this Buddha traveled to Kosala, Vaisali, Kapilavastu, Kausambhi, Veranja. (these areas are mainly in modern day Bihar and Uttar Pradesh).<br /><br />Very briefly his teachings are. Buddha’s repeated instructions were to pursue practical methods to arrive at the truth and not to distract themselves with academic speculations about the Beyond and the Ultimate. He propounded four Noble Truths – 1). That worldly existence is full of misery.2) that thirst, attachment are its causes. 3) that worldly misery can be ended with destruction of thirst. 4) there is a Path for destruction of thirst, it is known as the Eight fold way i.e. right speech, action, means of livelihood, exertion, right-mindedness, meditation, resolution and point of view. The first three lead to physical control, the next three to mental control and the last two to intellectual development.<br /><br />Nirvana is the final result of extinction of desires or thirst for rebirth. The Eightfold Path is said to be Buddha’s first discourse. The second discourse is that the five constituents, which make a being, are without a self, impermanent and are not desirable. There is nothing in this world to make one happy or sad and he, who is free, is perfect. There are reasons to believe that Buddhism like Jainism, was originally a moral code rather than a metaphysical or religious system in the western sense of the term. But a philosophical background became necessary for its propagation and existence. The first sign of this development was the sects of Hinayana and Mahayana. The first school looked at salvation of the individual as the goal whereas the other took the salvation of all beings as its goal. The first took to Prakrit while the second took to Sanskrit.<br /><br />Without admitting the existence of the soul, the early Buddhists accepted the theory of Karma i.e. the inevitability of the effects of deeds in regulating future births. Sankya, Yoga and the Upanishads were the sources of his inspiration. He was a product of the Aryan order and represented the ascetic orders against the social ideals of those who took life as a whole. He proclaimed the supremacy of Dharma but stressed on universal compassion. It was a Protestant movement within the fold of Dharma with its empathy for the suffering as its biggest attraction.<br /><br />Sangha – In the earlier stages, Buddha’s disciples led a wandering life, residing in caves and forests, living on alms. They assumed the tile of bhikkhu or beggar. Buddha was not in favor of extreme austerity, he permitted his disciples to live in monasteries esp. built for them, accept food/clothes from the faithful. He framed a set of rules for residents of these monasteries. Monastic institutions were the most remarkable contribution of Buddhism to Indian culture. Their original purpose was give suitable accommodation to the monks for studies and mediation. Later on they developed into academic centers for producing the right types of men, well grounded in religion and philosophy, to propagate the teachings of Buddhism.<br /><br />Buddha, inspite of his heterodoxy, left a lasting influence on Dharma. First he was revered as an ascetic reformer, in the process of a general acceptance by the masses he became a divinity. On the other hand, Krishna was ‘Sasavata Dharmagopta’, the Protector of Eternal Dharma, Buddha also proclaimed Dharma and asked people to surrender themselves to it. Buddha died in 486 BC.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0tag:blogger.com,1999:blog-7754475997061844069.post-82409349340257246352008-11-19T08:05:00.000-08:002008-12-23T01:17:25.197-08:00CHANAKYA - KautilyaWhen ever I have spoken to friends about Kautilya (K) or his master piece Arthashastra (A), they looked at me sheepishly, as if saying, why I wanted to talk about that smarty, teacher of unethical practices and advocate of the theory that the end justifies the means. Both K (known as Chanakya(C)) and his masterpiece are misunderstood. He is compared to Machiavellain. He laid great emphasis in the welfare of the people. As a teacher of practical statecraft, he advocated unethical methods to pursue national interests. It was the victory of Dharama over Adharama. Is that not what the Mahabharat is all about ? Do not read his thoughts with a India centric perspective. The teachings of the great preceptor of statecraft have global applications.<br /><br />Nearly hundred years ago, Swami Vivekananda said, what India brings to the world is intellectual capital and spirituality. While the world has accepted India as a fountainhead of spirituality, it has taken the success of the Indians American community for the world to sit up and take notice. The community has used its intellect to make correct decisions, taken risks, worked hard. Fortunately, they continue to retain and espouse Indian values. Humility is what one associates with them. Making Profit, earning money was considered healthy in ancient Bharat provided it was distributed for the benefit of others. Some of them have donated big monies to the I.I.T’s. This essay is dedicated to the Indian American community. They have used their clout to change the way the American Government views India. Coming after Pokran II and the sanctions that followed it was no mean task. I would urge all Indians to shed their inhibitions of the Nehru/Indira era & move out of country to share their intellectual power with the world.<br /><br />This essay is based on inputs from Kautilya, the Arthashashtra by Shri L N Rangarajan and The History & Culture of Indian People by the Bhartiya Vidya Bhavan..<br /><br />Artha - From ancient times, the aim of all human endeavor was dharma, artha, kama and moksha meaning moral behavior, wealth, worldly pleasures and salvation. Of these dharma is the most important. It signifies the concept of righteousness and ones duty to family, society and universal order. Artha follows dharma but it has a much wider significance than merely “ wealth”.<br /><br />The material well being of human beings is closely linked to it. The government plays an important role in helping its inhabitants to generate wealth. The aim of pursuing successful economic policies is to increase the revenues of the state and its people. A depleted treasury cannot serve its citizens but if a full treasury is achieved by high taxes it does not serve any purpose either. This assumes two things – maintenance of law & order and administrative machinery. Thus A, attaches importance to economics, dandaniti (use of a rod to maintain law & order) and the welfare of people (success of administrative system).<br /><br />A is thus, the art of governance in its widest sense. The subjects covered include administration, law & order, taxation, revenue, foreign policy, defence, war. K was not the originator of the science. He acknowledges that it is based on similar treatise of the past. There are believed to be thirteen individual teachers of A before K.<br /><br />Who was Kautilya ? His name was Vishnugupta. He is believed to be from Kerala or a North Indian who was born & educated in the university town of Taxila. A knowledgeable person he landed up in the court of the Magadha (in Bihar) king Dhana-Nanda to display his knowledge. Humiliated by the King, he vowed not to tie his forelock knot again until he had destroyed the Nanda dynasty. While searching for a person who would help him achieve his objective, he came upon Chandragupta, took to him to Takshila and gave him education fit for a future king. Whether K existed in 320 bc or 150 ad in no way undermines the greatness of his thoughts and writings.<br /><br />Strategy - They started attacking the Nanda empire but failed. Legend has it that they understood the reasons for their failure when they heard a women scold her child “ You are just like Chandragupta (CG)! Because her son had got his fingers burnt by starting to eat from the center of a hot dish.” They changed their tactics and began to attack from the frontiers. What CG was doing earlier was to try and capture the interior areas. After capturing one area he would go for another but would face in a revolt in the area previously captured. So when you have to capture, go step by step, take the outer areas first, establish physical control, that way your opponents have to keep on moving inland, keep up the pressure and they have to succumb.<br /><br />You cannot stand in the center and win a war. Remember the fate of Abhimanyu, he entered the Chakravuyaha, got right in the centre, could not withstand the attack from all sides. Lets look at the fate of the Indian Army in Jammu and Kashmir. It is perceived that they do not attack but always respond. They have not cordoned off areas pushing their opponents into a corner and then go for the kill. What I would do is to clean up each district in Jammu first, establish complete control, cover my back side, force the terrorists into the Valley, block their exit into Kargil by manning Zojila Pass and then go for the kill in Kashmir Valley. But as a nation we have rarely been proactive, let the person attack and then defend is our motto.<br /><br />K and CGupta changed their strategy and began attacking from the frontiers till they converged on Pataliputra, defeated the Nanda king and installed CG as king.<br /><br />History - Alexander invaded India in 326 bc. The nature and effect of his raid on India are highly overstated. He never crossed the Beas and thus never fought any of the brave kings of Bharat. His conquest of Punjab had no permanent impact, politically, administratively or in a cultural sense. But his invasion affected Indian politics to the extent that it promoted the political unification of India. Smaller states merged into big ones, paving the way for the growth of the Indian empire founded by Chandragupta, guided by Kautilya. It however, opened up communication between India and Greece at a great cost though. His visit inflicted untold sufferings upon India, rape, massacre, plunder on a scale that was unknown to us Indians. He prepared us by similar actions by the Muslim invaders. CG began the war of liberation around 321 bc and became king about 324 bc. In 305 bc, he defeated the Greek king, Seleucus, who had succeeded Alexander in the eastern part of the empire. His empire extended up to Mysore in the South, Persia in the North-West, Gujarat in the West and probably Bengal in the East.<br /><br />Arthashastra broadly covers fourteen areas. One deals with the King – his training, appts of minister etc. Two describes the duties of various officers of the state and gives a complete picture of the states activities. Three is concerned with law and administration of justice. Four is on suppression of crimes. Five is a sundry collection of topics including salaries of officials. Six is on foreign policy and constituent elements of state. Seven is an exhaustive discussion on the way in which each of the six methods of foreign policy may be used in various situations. Eight relates to calamities. Nine is on preparations of war. Ten is concerned with fighting and types of battle arrays. Eleven is on how must a conqueror deal with a number of chiefs rather than one king. Twelve shows how a weak king when threatened by a stronger one must overpower him. Thirteen is concerned with the conquest of the enemy’s fort by fighting. Fourteen deals with occult practices.<br /><br />It is not possible to cover the entire treatise in one short, so will take individual topics.Sumedhhttp://www.blogger.com/profile/11533458660230230361noreply@blogger.com0