Paper with lots of Greek letters I developed a system, and wrote a paper about it.  It includes formulas and pseudo-code.  During the course of development I used Roman letters in the formulas.  I eventually ran out of meaningful letters (letters that I could associate to some extent with what they represented), and started using Greek letters.  The development went on until somehow I ended up having about 8 Greek letters and 2 Roman letters used in the final formulas and pseudo-code.

Now that the paper is written, I wonder if having all of these Greek letters is unusual.  Would it be better to replace them with Roman letters?  Would it be better to use Roman letters with subscripts, such as t for time, and t_scaled for scaled time, instead of using Greek letters for that?

EDIT: To clear things up a little, my general question is: is it preferable to use Roman letters or Greek letters in a technical (engineering) publication, and is it acceptable or even preferable to use letters with word subscripts instead of entirely new symbols to label related variables or constants?
This depends entirely on your field, and specifically, what the norm is in your field. In mathematical fields like statistics, economics, physics, and math itself, and to a slightly lesser extent in chemistry and computer science, using Greek letters as variables is exceedingly common - in fact, it's unusual to see a paper that doesn't use a few, and there are many quantities for which the well-established standard notation involves a Greek letter. In other fields, perhaps that's not the case.

If you're still not sure after examining the norms in your field, I'd just go ahead and do it. Given that mathematicians use Greek letters all the time, it stands to reason that when you are doing math in another field, you should be able to do so as well.

However, I would caution you about one thing: try to make your variable names descriptive. That is, it should be easy for the reader to make the association between the variable name and what it represents. So when there is a standard notation for some quantity, use that; when there isn't, subscripted symbols like "t_scaled" are one good way to do it. They do take up more space on the page, though, and can make formulas look unwieldy, so you have to strike a balance between aesthetics and clarity of meaning.