On-Line Calculators

Most of the time when we visit a web site for engineering or other technical information we simply read words or view pictures and drawings. However, the use of interactive web sites allows sites to provide calculators without having to load programs on our computers.

The largest category of interactive technical tools is unit conversion calculators. These differ from the static pages listing unit conversions; the static conversion tables only list the constant, while most of the interactive calculators allow you to enter a value and the web site software does the conversion for you.

One particularly useful site is the unit conversion calculator provided by CRM Engineering Services and it's principal, Charles R. McCreary, P.E (www.texramp.net/~mccreary/Units/Units.html). At this site you choose a type of measurement (e.g. area, temperature, etc.). A form appears with many S.I. and English units (e.g. acres, square miles, square feet, sq. kilometers, etc.). You enter a value into the space for the known units, and the table will then be filled in with the others.

One of the most comprehensive conversion programs is a Java based web site by Digital Generation, www.webcom.com/~legacysy/convert2/convert2.html. This is one of the only conversion calculators I have found that had such units as barns and darcys. If your browser does not support Java, there is a link on the page to a form based converter that should be compatible with some of the older browsers.

There are several sites that provide interesting and useful technical calculations. "The Integrator", www.integrals.com, is provided by Wolfram Research, the creator of a PC based mathematical tools program called "Mathematica". This site provides a demo of the Mathematica package by solving an integral entered by the user.

Several calculation programs are available at Connel Internet Marketing’s site, www.connel.com. One is a fluid flow calculator by Michael J. Rocchetti, PE, that calculates pipe friction losses for straight piping handling water (or water - ethylene glycol mixtures) using the Darcy-Weisbach equation, the Colebrook equation, and the Moody equation.

Another site that features programs by Michael Rocchetti is the University of Connecticut Architectural & Engineering Services at www.sp.uconn.edu/~wwwfmo/tools/tools.html. It’s collection of tools include the Fluid Flow Calculator, an Engineering Units Conversion Calculator, an Engineering Economics Calculator, a Psychometric Calculator, Saturated Steam Tables, and an Air Duct Calculator.

A rather interesting site is the calculator-in-the-URL page $urlcalc(help).x42.com. At this site you can perform certain (rather limited) calculations by including the calculation in the URL you type to go to a page. For example, if you go to http://$sqrt(16).x42.com you will be taken to a page that correctly gives the answer as 4.

David Sumner of the Department of Mathematics of the University of South Carolina

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