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According to the requirements in real-time, accuracy and convenience characteristics of pre-warning technology in coal and gas outburst, the characteristics and regularity of electromagnetic radiation in coal and rock fracture, and regularity and relativity of electromagnetic radiation and conventional indexes during coal and gas outburst evolution were analyzed. The coal and gas outburst electromagnetic radiation warning equipment and software were developed. The pre-warning criteria of coal and gas outburst forecasting with electromagnetic radiation was built. The automatic analysis and pre-warning of electromagnetic radiation in coal and gas outburst forecasting was realized. The results showed that there was high positive correlation between electromagnetic radiation and conventional indexes of coal and gas outburst, which could reflect coal and gas outburst risk. The field application of coal and gas outburst pre-warning results showed that electromagnetic radiation had high pre-warning accuracy, and could predict outburst hazard ahead 13 meters or ahead two days. [ABSTRACT FROM AUTHOR]

Cocrystallizationof a versatile organic tecton, 3,3′,5,5′-tetramethyl-4,4′-bipyrazole(tmbpz), with aliphatic dicarboxylic acid suberic acid (H2sub) and sebacic acid (H2seb) generates two supramolecularsolids [(tmbpz)2·(H2sub)] (1) and [(tmbpz)2·(H2seb)] (2). In the present case, both cocrystals could be obtained from eithersolution evaporation or mechanochemical solid-state reaction. Single-crystalstructural analyses reveal that the 1and 2are 4-fold and 5-fold 2D → 2D parallel interpenetrated 63-hcb networks, respectively. The substantial dissimilaritiesin the degree of interpenetration are modulated by the different lengthsof dicarboxylic acids. The thermal stabilities and photoluminescencebehaviors of them were also discussed. [ABSTRACT FROM AUTHOR]

In order to study the surface electric potential signals during the coal adsorbing gas, designed the experiment system of the coal adsorbing gas and tested the electric potential signal generated during the coal adsorbing gas under different gas pressure. Experiment results show that surface potential signals can be generated in the process of adsorbing gas, and they increases gradually along with the growth of adsorption time. For the same coal samples, different gas pressure from the coal surface potential signal to the first adsorption gas pressure of coal potential signal has a memory effect in the process of absorption. When the adsorption gas pressure is higher than the first adsorption gas pressure, the coal induces stronger surface potential signals. And when the adsorption gas pressure is lower than the first adsorption gas pressure, the coal induce weaker surface potential signals. The main reasons why surface potential signals can be generated from coal adsorbing gas are that the gas seepage in coal pores produces flow potential and free charge is generated when the gas damages micro cracks and crack of coal. [ABSTRACT FROM AUTHOR]

An investigation was conducted on the characteristics of surface current induced by coal under uniaxial compression. An interpretation of the mechanisms governing the electrical behavior of the coal structures under uniaxial stress tests was presented in this paper. The experimental results show that the current signal is generated during the deformation and fracture process of coal samples. When the load is applied, the electric current makes its initial appearance and increases rapidly after a considerable time lag at 8C, until after the stress reaches a value δc ≈0.75δmax where δmax is the maximum applied stress before sample fracture. There is a good correlativity between the current and the load, and the correlation coefficient between them can reach up to 0.8 to 0.9. The current peaks occur under sudden loading and unloading. It suggests that the current is closely related to the loading. The status of coal loading level may be determined by the current signal. The intensive study on coal surface current can provide a way for monitoring the stability of coal and rock. [ABSTRACT FROM AUTHOR]

The experiment was made on the rules of surface potential of coal or rock during friction process. The mechanism producing surface potential of coal or rock friction was discussed initially. The results show that surface potential can be produced during coal or rock friction process, and it has a better corresponding relationship with load. The coal or rock friction process can be divided into two stages: static friction stage and kinetic friction stage. The surface potential signal in kinetic friction stage was stronger than that in static friction stage. During rock friction process, the polarity of surface potential signal was basically bidirectional mutation, and the polarity of surface potential on both sides of friction surface had obvious symmetry. While the polarity of surface potential signal was basically unidirectional mutation in coal friction process, and the polarity of surface potential on both sides of friction surface was not in significant symmetry. The changes of surface potential during coal or rock friction process can be explained by mechanism of electricity produced by friction, thermionic emission and field electron emission. [ABSTRACT FROM AUTHOR]

In order to study the relationship between surface potential distribution and destruction localization of the coal sample, the distribution law of strain field and surface potential of coal samples were tested under load. The relationship between surface potential field and strain localization & fracture of coal samples was studied and analyzed. Results show that the coal samples show obvious strain localization characteristics in deformation and failure process, the strain localization concentrated area is the severe damage and fracture part of coal samples, and the strain localization zones is usually the fracture location of coal samples. The distribution character of surface potential field of coal samples during deformation and fracture is similar to the strain field, the potential field will be centralized in the damage localization area, the connection between the points of high potential and low potential reflects the rupture section of coal samples. [ABSTRACT FROM AUTHOR]

The controllable key factors in magnetorheological finishing device were studied to determine their influence on efficiency of magnetorheological finishing ( MRF ) and surface of MRF, as well as interaction between efficiency and surface. Based on theoretical and experimental research, the law of material removal was explored and a new process variable based material removal model (PVMR) was proposed. The experimental findings demonstrate that PVMR reveals the law of the material removal with introduction of three concepts and makes a material removal function z (y i) where the magnetorheological finishing process parameters are considered since they are easy to control and adjust. So the material function of this model is quadratic curve function which is readily suitable for stability and online control magnetorheological finishing. [ABSTRACT FROM AUTHOR]