Finding local minima and maxima of DSC curves using islocalmin and islocalmax
26 visualizzazioni (ultimi 30 giorni)
DSC (Differential Scanning Calorimetry) is a thermal analysis method used in material science and chemistry to understand the thermal behavior of polymers or other organic/inorganic materials. The test is usually performed by a first heating cycle (to melt all the microcrystalline regions), followed by a cooling phase and a second heating. It is during the cooling and second heating that the crystallization and melting temperatures of a material are measured in the form of the temperature at which the heating has a local minimum or maximum.
The issue here: it is highly desirable to have a process for finding the crystallization and melting temperatures automatically, and I tried to use the islocalmin and islocalmax functions of matlab to find these values. As can be seen, multiple local minima and maxima are detected (symbols: red for minima and blue for maxima) but a lot of junk is also detected. In addition, there is an overlap in the minima and maxima, which means that, for some reason that I cannot understand, the program considers these both as minima and maxima. This is especially problematic in the section where a large naumber of points are detected nect to each other.
What I am interested in is only the local mainima/maxima pointed to by arrows. Is there a way to make the detection more specific to avoid the multiplicity seen here and reliably detect the most crucial points?