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Wave propagation in a magneto-electro- elastic plate

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Science China(Physics,Mechanics & Astronomy) 2008年第6期51卷 651-666页

作者： wei jianping SU XianYue State Key Laboratory for Turbulence and Complex System and Department of Mechanics and Aerospace Engineering Peking UniversityBeijing 100871China

The wave propagation in a magneto-electro-elastic plate was studied. Some new characteristics were discovered: the guided waves are classified in the forms of the Quasi-P, Quasi-SV and Quasi-SH waves and arranged by the standing wavenumber; there are many patterns for the physical property of the magneto-electro-elastic dielectric medium influencing the stress wave propagation. We proposed a self-adjoint method, by which the guided-wave restriction condition was derived. After the corresponding orthogonal sets were found, the analytic dispersion equa-tion was obtained. In the end, an example was presented. The dispersive spectrum, the group velocity curved face and the steady-state response curve of a mag-neto-electro-elastic plate were plotted. Then the wave propagations affected by the induced electric and magnetic fields were analyzed.

关键词： magneto-electro-elastic plate guided-wave restriction condition dispersive equation dispersive spectrum group velocity curved face steady-state response curve

3D numerical simulation of boreholes for gas drainage based on the pore–fracture dual media

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International Journal of Mining Science and Technology 2016年第4期26卷 739-744页

作者： wei jianping Li Bo Wang Kai Sun Donghui State Key Laboratory Cultivation Base Henan Province Key Laboratory of Gas Geology and Gas Control Henan Polytechnic University Jiaozuo 454003 China Collaborative Innovation Center of Coal Safety Production of Henan Province Jiaozuo 454003 China Henan Province Key Laboratory of Biogenic Traces and Sedimentary Minerals Henan Polytechnic University Jiaozuo 454003 China School of Resources and Safety Engineering China University of Mining and Technology Beijing 100083 China

A gas migration controlling equation was formulated based on the characteristics of the dual pore–fracture media of coal mass and in consideration of the matrix exchange between pores and fractures.A model of permeability dynamic evolution was established by analyzing the variation in effective stress during gas drainage and the action mechanism of the effect of coal matrix desorption on porosity and fracture in the coal body.A coupling model can then be obtained to characterize gas compressibility and coal deformability under the gas–solid coupling of loading *** addition,a 3D model of boreholes was established and solved for gas drainage based on the relevant physical parameters of real *** comparison and analysis results for the law of gas migration and the evolution of coal body permeability around the boreholes before and after gas extraction between the dual media and the single-seepage field models can provide a theoretical basis for further research on the action mechanism of gas drainage.

关键词： Pore-fracture Matrix exchange Coupling model Numerical simulation Gas drainage

Research on Distributed Coordination Control Method for Microgrid System Based on Finite-time Event-triggered Consensus Algorithm

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Chinese Journal of Electrical Engineering 2024年第2期10卷 103-115页

作者： Lizhen Wu Heng Yang jianping wei Wendong Jiang College of Electrical and Information Engineering Lanzhou University of TechnologyLanzhou 730050China National Active Distribution Network Technology Research Center Beijing Jiaotong UniversityBeijing 100044China

Microgrids are networked control systems with multiple distributed generators(DGs).Microgrids are associated with many problems,such as communication delays,high sampling rates,and frequent controller updates,which make it challenging to realize coordination control among the ***,finite-time consensus algorithms and event-triggered control methods are combined to propose a distributed coordination control method for microgrid *** DG in the microgrid system serves as an agent node in the control network,and a distributed secondary controller is designed using finite-time consensus algorithm,such that the frequency and voltage restoration control has a faster convergence time and better anti-interference *** event-triggered function was designed based on the state information of the *** controller exchanges the state information at the trigger *** stability is analyzed using the Lyapunov stability theory,and it is verified that the controller cannot exhibit the Zeno phenomenon in the event-triggered process.A simulation platform was developed in Matlab/Simulink to verify that the proposed control method can effectively reduce the frequency of controller updates during communication delays and the burden on the communication network.

关键词： Microgrid event-triggered control distributed secondary control finite-time consensus algorithm coordination control

Combined control of fluid adsorption capacity and initial permeability on coal permeability

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International Journal of Coal Science & Technology 2022年第6期9卷 127-137页

作者： Xiaolei Liu jianping wei Guoying wei Caifang Wu Cao Liu Xiaoming Ni State Key Laboratory Cultivation Base for Gas Geology and Gas Control Henan Polytechnic University454000 JiaozuoHenanChina College of Safety Science and Engineering Henan Polytechnic University454000 JiaozuoHenanChina State Collaborative Innovation Center of Coal Work Safety and Clean-efficiency Utilization 454000 JiaozuoHenanChina Key Laboratory of Coalbed Methane Resource and Reservoir Formation Process Ministry of EducationSouth Jiefang Road221008 XuzhouJiangsuChina Collaborative Innovation Center of Coalbed Methane(Shale Gas)in Central Plains Economic Zone 454000 JiaozuoChina

The variations of strain and permeability of coal were systematically studied through the physical simulation of N2 and water *** effects of fluid adsorption capacity and initial permeability on strain,permeability and the dominant effect of pore pressure were *** adsorption strain and strain rate of coal during water injection are significantly higher than those during N2 *** edge of free adsorption exists in the early phase of N2 and water injection,which is related to fluid *** this boundary,the strain rate and pore pressure are ***,the injec-tion time of initial stage accounts for about 20%of the total injection time,but the strain accounts for 70%of the total *** water injection,this boundary is about half of water saturation of ***,the influence of pore pressure on permeability is complex,which is controlled by adsorption capacity and initial permeability of *** the initial permeability is large enough,the effect of adsorption strain on permeability is relatively weak,and the promoting effect of pore pressure on fluid migration is ***,the permeability increases with increasing pore *** the initial permeability is relatively low,the pore pressure may have a dominant role in promoting fluid migration for the fluid with weak adsorption ***,for the fluid with strong adsorption capacity,the adsorption strain caused by pore pressure may play a leading role,and the permeability reduces first and then ascends with increasing pore pressure.

关键词： Initial permeability Adsorption capacity Free adsorption Pore pressure Coal strain

Inverse Modeling of Nonlinear Systems and Application

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 302-305页

作者： jianping wei Huade Li Datai Yu(Information Engineering school, University’ of Science and Technology’ Beijng, Beijing 1 00083, China) Information Engineering School University of Science and Technology Beijing Beijing 100083 China

Inverse modeling is discussed based on neural networks. U-D factorization Kalman filter learning algorithm is introduced totrain a feed forward multilayer neural network, which is used as inverse models. A scheme of D... 详细信息

关键词： neural network modeling control DC EAF

Effect of protective coal seam mining and gas extraction on gas transport in a coal seam

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International Journal of Mining Science and Technology 2016年第4期26卷 637-643页

作者： Yao Banghua Ma Qingqing wei jianping Ma Jianhong Cai Donglin State Key Laboratory Cultivation Base for Gas Geology and Gas Control Henan Polytechnic University Jiaozuo 454000 China School of Safety Science and Engineering Henan Polytechnic University Jiaozuo 454000 China Collaborative Innovation Center of Coal Work Safety of Henan Province Jiaozuo 454000 China

A gas–solid coupling model involving coal seam deformation,gas diffusion and seepage,gas adsorption and desorption was built to study the gas transport rule under the effect of protective coal seam *** research results indicate:(1) The depressurization effect changes the stress state of an overlying coal seam and causes its permeability to increase,thus gas in the protected coal seam will be desorbed and transported under the effect of a gas pressure gradient,which will cause a decrease in gas pressure.(2) Gas pressure can be further decreased by setting out gas extraction boreholes in the overlying coal seam,which can effectively reduce the coal and gas outburst *** research is of important engineering significance for studying the gas transport rule in protected coal seam and providing important reference for controlling coal and gas outbursts in deep mining in China.

关键词： Protective coal seam mining Seepage characteristic Coal and gas outburst Numerical simulation

A rapid and accurate direct measurement method of underground coal seam gas content based on dynamic diffusion theory

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International Journal of Mining Science and Technology 2020年第6期30卷 799-810页

作者： Yanwei Liu Yang Du Zhiqiang Li Fajun Zhao weiqin Zuo jianping wei Hani Mitri School of Safety Science and Engineering Henan Polytechnic UniversityJiaozuo 454000China The Collaborative Innovation Center of Coal Safety Production of Henan Province Jiaozuo 454000China Department of Mining and Materials Engineering McGill UniversityMontreal H3A0E8Canada School of Civil Engineering Henan Polytechnic UniversityJiaozuo 454000China

Coal seam gas content is frequently measured in quantity during underground coal mining operation and coalbed methane(CBM)exploration as a significant basic *** to the calculation error of lost gas and residual gas in the direct method,the efficiency and accuracy of the current methods are not inadequate to the large area multi-point measurement of coal seam gas *** paper firstly deduces a simplified theoretical dynamic model for calculating lost gas based on gas dynamic diffusion ***,the effects of various factors on gas dynamic diffusion from coal particle are experimentally *** sampling procedure of representative coal particle is ***,a new estimation method of residual gas content based on excess adsorption and competitive adsorption theory is *** results showed that the maximum error of calculating the losing gas content by using the new simplified model is only 4%.Considering the influence of particle size on gas diffusion law,the particle size of the collected coal sample is below 0.25 mm,which improves the measurement speed and reflects the safety representativeness of the *** determination time of gas content reduced from 36 to 3 h/***,the absolute error is 0.15–0.50 m^3/t,and the relative error is within 5%.A new engineering method for determining the coal seam gas content is developed according to the above research.

关键词： Coal seam gas content Dynamic diffusion model Determination method Lost gas content Desorption characteristics

Determination of indices and critical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine

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International Journal of Mining Science and Technology 2012年第1期22卷 89-93页

作者： Ou Jianchun Liu Mingju Zhang Chunru Liu Yanwei wei jianping School of Safety Engineering Chino University of Mining&TechnologyXuzhou 221008China Science and Engineering Henan Polytechnic UniversityJiaozuo 454003China Xieqiao Mine of Huainan Mining Industry Group Huainan 232001Chino

Based on the important role in mine safety played by parameters of the first gas outburst, we propose a method of combining historic data, theoretical analysis and experimental research for the purpose of crit- ical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine. According to a characteristic analysis and a summary of the rules of coal and gas outbursts in the No.8 coal seam of a Hua- inan mine, we have investigated their effect on coal and gas outbursts in terms such as ground stress, gas, and coal structure. We have selected gas parameters and determined the critical values of each of the fol- lowing indices： gas content as 7.7 m^3/t, tectonic coal as 0.8 m thick, the absolute gas emission as 2 m3/min, the rate of change as 0.7 m3/min, the gas desorption index of a drilling chip KI as 0.26 mL/（g min^1/2） and the values of desorption indexes Ah2 as 200 Pa. From a verification of the production, the results indicate that application of each index and their critical values significantly improve the level of safety in the pro- duction process, relieve the burden upon the mine, save much labor and bring clear economic benefits.

关键词： Parameters of first gas outburst Gas content Thickness of tectonic coal Critical value Coal and gas outbursts

A method of determining the permeability coefficient of coal seam based on the permeability of loaded coal

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International Journal of Mining Science and Technology 2014年第5期24卷 637-641页

作者： Li Bo wei jianping Wang Kai Li Peng Wang Ke State Key Lab Cultivation Base Henan Province Key Lab of Gas Geology & Gas Control Henan Polytechnic University School of Materials Science and Engineering Henan Polytechnic University School of Resources & Safety Engineering China University of Mining & Technology

This study developed the equipment for thermo-fluid–solid coupling of methane-containing coal, and investigated the seepage character of loaded coal under different working conditions. Regarding the effective pressure as a variable, the variation characteristics of the gas permeability of loaded methane-containing coal has been studied under the conditions of different confining pressures and pore pressures. The qualitative and quantitative relationship between effective stress and permeability of loaded methane-containing coal has been established, considering the adsorption of deformation, amount of pore gas compression and temperature variation. The results show that the permeability of coal samples decreases along with the increasing effective stress. Based on the Darcy law, the correlation equation between the effective stress and permeability coefficient of coal seam has been established by combining the permeability coefficient of loaded coal and effective stress. On the basis of experimental data, this equation is used for calculation, and the results are in accordance with the measured gas permeability coefficient of coal seam. In conclusion, this method can be accurate and convenient to determine the gas permeability coefficient of coal seam, and provide evidence for forecasting that of the deep coal seam.

关键词： Permeability coefficient Coal seam Effective pressure Loaded coal Pore pressure