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Land subsidence and ecological deterioration will be caused by underground coal mining, and a series of geological and environmental would occur frequently. The main mining areas in northwest of China are located in the arid loess mountain area, itself belongs to susceptible area of natural geologic hazard, and often happens mining subsidence. Fast large scale mapping of mine is crucial for disaster relief when the mine geological environment and disasters. The traditional photogrammetry cannot be responded the condition of real-time for high cost and long cycle. In recent years, low altitude remote sensing system develops rapidly based on sensor of UAV, trike, multi rotor aircraft by their low cost, miniaturization, customization, speed and other advantages. This paper used delta wing to survey the Ningtiaota Coal Mine in northern shaanxi. The research got DSM and DTM of mine by image control point and aerotriangulation, which comply with the requirements of the measurement accuracy, In this study, a fast mapping method of large area and large scale topographic map was developed to improve the monitoring, prediction and evaluation of land and environmental damage in mining area.

Publisher Summary This chapter illustrates an experiment, with detailed analysis of mixture properties and cycle configuration, to reach about 65 to 70 K temperature range by using a mixed-gases Joule-Thomson system. A special cycle configuration is disclosed utilizing a newly developed fractional phase-separator with inner heat and mass transfer. This separator avoids cold clogging essentially. An optimal mixture is used to improve the system performance. A stable lowest temperature at 66 K and 1.06 W cooling capacities at 70 K are achieved with an input power of 0.5 kW, driven by a commercial single-stage hermetic compressor with a nominal input power of 500 W. The results obtained in this investigation show that with optimal mixed-refrigerant and cycle configuration, the mixed-refrigerant J-T cryocooler can provide refrigeration at 70 K temperature properly. This provides a low cost, high reliability refrigerator for 70 K temperature range application, especially for cooling high temperature superconductivity devices.

Publisher Summary This chapter presents thermodynamic models to analyze the thermodynamic performances of those throttle refrigeration cycles, especially the recuperative mixed-refrigerant cycles for low temperature refrigeration applications. Numerous cycle configurations have been presented based on the Joule-Thomson effect of real gases for different refrigeration applications from cryogenic temperature to room temperature. Using throttle device to produce refrigeration is the general feature among those refrigeration cycles, such as the vapor-compression cycle, the cascade cycle, the single-stage recuperative cycle with mixed-refrigerants, and the dual mixed-refrigerant cascade recuperative cycle. The Carnot efficiency is used as a comparison criterion in the comparisons of all those throttle cycles at different refrigeration temperature ranges. The results show that with optimal mixture and cycle configuration, the low-temperature recuperative refrigeration cycle can achieve a high performance as good as the commercial vapor compression cycle. The optimized results at ideal compressing-process conditions show that all the throttle cycles can provide near equivalent values even providing refrigeration from cryogenic temperature to near room temperature ranges.

The HT-7 Superconducting Tokamak is being built in Hefei, China. It is a device reconstructed and upgraded from T-7 Tokamak of Russia. This project is a co-operating item of fusion research between Russia and China. The Research and Manufacturing Center (RMC), ASIPP is responsible for the fabrication and assembly of HT-7. The design of HT-7 was carried out by both of Russian and Chinese engineers in 1991, and the main parts of the machine were fabricated in 1992. The preassembly of HT-7 was completed in April, 1993. This paper emphasizes on the manufacturing steps necessary to produce the HT-7 and a series of technological methods to overcome the key techniques.

The paper presents technical schemes and technological methods on the reconstruction of HT-7 current leads unit to satisfy physics requirements. At first, structure characteristics and design parameters on the current leads are described. The comparison between the former leads and the new ones is made. Secondly, fabricating steps necessary to reconstruct the leads and a series of technological methods to solve the techniques are reported. Then, based on the stress analysis and mechanical properties at low temperature on some kinds of materials used in LHe system, the stress weak links and improvement methods are discussed. Finally, the vacuum test and status of LHe system including the current leads after rebuilding are given.