Cleaning Up Some Old Work

I was going through some old work and thought I would update some of my programs in a recent version of Microsoft Visual Studio. Old dogs and new tricks so to speak, but Visual C# is sufficiently similar to Visual C++ so it wasn't too bad. One of those was a program to fit curve parameters. The routine and the results are shown below the break. I will be making the executable file available on the Google Drive in the Downloads area in the very near future.

Much of my professional career was associated with energetic materials, specifically performance of explosives. One of the tools needed for that work was a fairly accurate description of the reaction products. This is known as the reaction product equation of state. There are a number of types of equations of state used but one of the more common ones is the Jones-Wilkins-Lee, or JWL, equation of state for the isentrope. The curve describes the relationship between pressure and specific volume which goes to the primary ability of an explosive material to do work.

The curve fit is not really that fancy, in fact it's a somewhat standard routine that I modified for my purposes. The rest of the program is an attempt to efficiently take in a simple P-v file produced in Excel and then create a fit, and subsequent plot routines for reporting the data in a timely manner. The P-v data is determined by the Cylex test, and its data reduction is another program that I am also updating. Two of the plots are shown below. The first is the data versus the fit and the pressure residuals. Then a close-up view of the bend in the curve (the more difficult part to fit), and a close-up of the tail of the isentrope where a significant amount of work is available.