In this paper, the thermodynamic parameters such as Grüneisen parameters and anharmonicity are investigated utilizing pressure- and temperature-dependent Raman spectroscopy of monolayer transition-metal dichalcogenides MX2 (M = Mo, W; X = S, Se). The result indicates a good stability of these compounds in the pressure range of 0–9.0 GPa and the temperature range of 175–575 K. It is a general trend that Raman mode varies with temperature and pressure linearly for monolayer MX2, and the thermodynamic Grüneisen parameters can be determined from the temperature- and pressure-dependencies of Raman spectra. Based on these measurable parameters, anharmonic parameters are extracted for each active Raman mode. The result shows that the temperature dependencies of the phonon frequencies are well described by considering the contributions from thermal expansion and lattice anharmonicity.

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Train wheel sets must be periodically inspected for possible or actual premature failures and it is very significant to record the wear history for the full life of utilization of wheel sets. This means that an online measuring system could be of great benefit to overall process control. An online non-contact method for measuring a wheel set’s geometric parameters based on the opto-electronic measuring technique is presented in this paper. A charge coupled device (CCD) camera with a selected optical lens and a frame grabber was used to capture the image of the light profile of the wheel set illuminated by a linear laser. The analogue signals of the image were transformed into corresponding digital grey level values. The ‘mapping function method’ is used to transform an image pixel coordinate to a space coordinate. The images of wheel sets were captured when the train passed through the measuring system. The rim inside thickness and flange thickness were measured and analyzed. The spatial resolution of the whole image capturing system is about 0.33 mm. Theoretic and experimental results show that the online measurement system based on computer vision can meet wheel set measurement requirements.