The Writers background My career and working life since 1972 have been in the area of membrane filtration. Mostly in industrial application development, and mostly using plate-and-frame systems and spiral wound elements. I will add material to the homepage if I feel like it of if I am requested to do it. The Background for EXE-programs and Spreadsheets In the early days of membrane filtration (before 1974) computers as we know them today did not exist. Slide-rulers were the only "calculators" available for engineers. In 1972 even a hand held calculator did not exist. To solve a problem it was necessary first to develop differential equations (often quite complex) and then to solve the equations. In this way the number of calculations was limited and precise. Nevertheless, it was still hard work to calculated a complete system and it could take days. And the danger of mistakes was always present. Today, problems are solved by applying the computing power of modern computers in numerous iterations. You may ask: "Do we really need to apply the complex formulas resulting from solving differential equations?". My answer is YES. A formula will not only provide an answer, but a result. Although iterations may provide an answer, it is very difficult to gauge the accuracy of this answer. My experience is, that the result of an iterative calculation may be significantly different from the result produced by the appropriate formula. The Background for the Papers Some information is considered so simple or common knowledge or proprietary, that it is never written down in an easy-to-understand language. The papers presented here has usually been started with an innocent question like: "Can you please write a few pages about .... ". The papers are not theoretical considerations. They are practial answers to practical questions / problems / challenges. |
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