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In this paper,a recognition method of coal and gangue based on x-ray is studied. With the different density , the coal and gangue on a belt can be detected by x-ray. After penetrated by x-ray, with the acquisition of ray signal and image analysis, the gangue can be accurately distinguished from the coal. As a result, the quality of coal is improved. Proved by experiment, this method is more efficient and accurate than other methods.

Increasing number of refrigeration units has led to an increase of CO2 emissions and the destruction of the ozone layer. Using low global warming potential (GWP) refrigerants, improving the efficiency of vapour compression refrigeration (VCR) units, and minimising refrigerant leakages can reduce the global warming effect. Investigating the refrigerant distribution under varied operating conditions can provide a deeper understanding of refrigerant charge optimization. This study proposed a model of refrigerant mass distribution in a prototype oil-free VCR system using a linear compressor with variable strokes and R134a. The absence of the oil lubricant allows the adoption of compact heat exchangers, such as micro-channels, so that the total refrigerant charge can be reduced significantly. The predicted total refrigerant charge has a Mean Absolute Percentage Error (MAPE) of 3.7%. The simulation results indicate that refrigerant distributed in the condenser is most sensitive to operating conditions and total refrigerant charges. The refrigerant accumulated in the condenser is 6.8% higher at a total refrigerant charge of 0.33 kg than that of 0.22 kg. For a total refrigerant charge of 0.33 kg, 72.1% of the total refrigerant can accumulate in the condenser. At a fixed pressure ratio, the refrigerant as a two-phase form in the condenser decreases slightly with the increase of compressor strokes, resulting in a larger mass flow rate, thus cooling capacity. The present model can be adapted for optimization of a refrigeration unit and its components.

In this paper, an image processing and recognition system of the coal and gangue has been studied. We adopt digital video processing technology of high performance---DaVinci technology to design the system, which is made up by the chip DM6437 and some peripheral auxiliary equipment. The system takes advantage of the high performance of the chip to process the real-time image collected by the CCD camera. The system uses optimized image processing and recognition algorithms, and makes the recognition of coal and gangue by the different characteristic of their histograms. In the system, the histogram and processing image of coal and gangue can be displayed on the monitor.

A method based on infrared thermal wave to distinguish coal and waste rock is introduced. Infrared thermal wave detection technology, a fast and effective detection method, can detect different characteristics of coal and gangue on the surface or subsurface. Test showed that coal and waste rock can be distinguished effectively by processing their infrared thermal wave image.