Automatic and manual evaluation Screenshot TK04 evaluation software The measuring software automatically evaluates each single measurement immediately after finishing the temperature registration, using the evaluation parameters chosen by the user in the measuring configuration. For scientific purposes, additional evaluations with different parameters can be generated, viewed, export or printed after finishing a measuring series. Results can be transferred directly to the graphics program for plotting and quality analysis. For beginners, the software provides standard parameters valid for a wide range of sample materials and measuring conditions, while advanced users can choose individual parameters matching their particular measuring tasks.

Determining the optimal evaluation interval The beginning of a transient thermal conductivity measurement is influenced by the contact between probe and sample and by the individual properties of the probe, while later parts of the measuring curve are affected by reflections of the propagating heat wave at the probe ends and the sample boundaries. In-between is an undisturbed interval suitable for evaluation whose size and position can vary between measurements depending on sample material, sample size, probe type, contact, ambient conditions and similar factors. The TK04 software ensures optimal results by automatically determining the part of the registered temperature rise that best corresponds to the theoretical curve.

This is achieved by scanning the measured temperature curve with evaluation intervals whose length and start time are increased in steps of 0.5 seconds. To check the suitability of an interval for thermal conductivity determination, its temperature data are compared to the shape of the theoretical curve. The similarity of both curves is measured by the so-called LET value, which is calculated from the coefficients obtained by fitting the theoretical curve to the measuring data: the higher LET, the more similar are the shapes of the measured and the theoretical curve and the more accurate is the thermal conductivity value determined from the interval in question.

After determining the interval with the highest LET value, thermal conductivity is calculated and saved to the results file of the measuring series, along with the length and position of the evaluation interval. In addition, thermal conductivity values are calculated from all intervals having a minimum LET value. These additional thermal conductivities are stored in separate files for each single measurement to be used for quality analysis.

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