Based on the theory of hydro-mechanical transmission system, a new kind of gear shifting control scheme to improve work efficiency of hydro-mechanical transmission system was designed. By describing the work principles of crucial components mathematically, the dynamic model of hydro-mechanical transmission was constructed according to modular modeling method. The proposed efficient type shifting strategy was embedded in aforementioned model to predict its performance. The simulation results indicated the proposed strategy could improve hydro-mechanical transmission efficiency.

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Scientific supporting design is of great significance to ensure coal roadway stability. The three-step supporting design method is put forward for coal roadway support: The first step is preliminary design, determine the range of each supporting parameter according to the theoretical calculation and supporting experiences; the second step is numerical simulation calculation, choose the reasonable one through the comparison of schemes; the third step is field monitoring, verify the scheme applicability. After applying the three-step supporting design method to study 3# coal seam roadway in Guandi mine, the optimal supporting scheme is obtained, and good results of underground roadway are achieved, which ensure the stability of roadway surrounding rock. Meanwhile, some rules are summarized which provide references for future roadway supporting design.

Concerning the critical issue that how to measure the gain of AC open-loop of operational amplifier accurately, in the field of electronic measuring. The measure system design of the AC open-loop gain of amplifier is designed in the paper based on labVIEW. The system consists of two parts of hardware and software. The hardware is composed by the multifunctional signal source, the low noise preamplifier, the awaiting measured amplifier, the data acquisition card and the computer; the software is composed by the human-computer interface program, measurement program and data post-processing. Using the virtual instrument cross-correlation detection technology, it can measure the gain of amplifier AC open-loop accurately, with the function of acquisition, measurement, real-time display and playback, constituting a programming flexibility, concise and efficient, accurate measurement, higher resolution, steady performance personalized automatic measurement system.