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Drawing mechanisms for top coal in longwall top coal caving(LTCC):A review of two decades of literature

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International Journal of Coal Science & technology 2021年第6期8卷 1171-1196页

作者： Jiachen Wang Shengli Yang Weijie Wei Jinwang Zhang Zhengyang Song School of Energy and mining engineering China University of Mining and Technology-BeijingBeijing 100083China department of Civil engineering School of Civil and Resource EngineeringUniversity of Science and Technology BeijingBeijing 100083China Coal Industry engineering Research center of Top-coal Caving mining Beijing 100083China

This review details the state of the art in research on top coal drawing mechanisms in Longwall top coal caving(LTCC)by examining the relevant literature over the last two *** startswith an introduction of the brief history and basic procedures of *** framework of research on the drawing mechanism,basic concepts,and some theoretical models of LTCC are detailed in *** framework of top coal *** authors note that theTop coal drawbody(TCD),Top coal boundary(TCB)and Top coal recovery ratio(TCRR)are key factors in the ***-boundary-ratio(BBR)research system has been the classic framework for research over the last 20 *** modified Bergmark-Roos model,which considers the effects of the supporting rear canopy,flowing velocity of top coal,and its shape factor,is optimal for characterizing the TCD.A 3Dmodel to describe the TCB that considers the thicknesses of the coal seam and roof strata is *** *** testing and numerical simulation,the physical tests and numerical simulations in the literature are classified for ease of bibliographical review,and classic conclusions regarding the drawing mechanism of top coal are presented and discussedwith elaborate illustrations and *** deflection of the TCDis noted,and is caused by the shape of the rear *** inclined coal seam always induces a largerTCD,and a deflection in theTCDhas also been observed in *** effects of the drawing sequence and drawing interval on the TCRR are reviewed,where a long drawing interval is found to lead to significant loss of top *** flowing behavior and velocity distribution are also *** applications of drawingmechanisms forLTCCmines 4 summarizes over 10 cases where the TCRRof LTCCmines improved due to the guidance of the drawing *** final section provides a summary of the work here and some open *** investigations are highlighted to give researchers guid

关键词： Longwall top coal caving(LTCC) Top coal drawing Top coal drawbody(TCD) Top coal boundary(TCB) Top coal recovery ratio(TCRR)

End-on x-ray backlighting experiments for axial diagnostics of wire-array Z-pinch plasma on PPG-1

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Chinese Physics B 2017年第1期26卷 326-332页

作者： Shen Zhao Xinlei Zhu Huantong Shi Xiaobing Zou Xinxin Wang department of electrical engineering Tsinghua University Beijing 100084 China Shenzhen Institutes of advanced technology Chinese Academy of Sciences Shenzhen 518055 China

An X-pinch axial backlighting system has been designed to quantitatively measure the density distribution of wirearray Z-pinch plasmas. End-on backlighting experiments were carried out on a 200 kA, 100 ns pulsed-power generator（PPG-1） at the Tsinghua University. Compared with side-on backlighting, end-on measurements provide an axial view of the evolution of Z-pinch plasmas. Early stages of 2-, 4-, and 8-wire Z-pinch plasmas were observed via point-projection backlighting radiography with a relatively high success rate. The density distribution of Z-pinch plasma on the r–θ plane was obtained directly from the images with the help of step wedges, and the inward radial velocity was calculated. The ablation rates obtained by X-pinch backlighting experiments are compared in detail with those calculated by the rocket model and the results show consistency.

关键词： X-pinches axial backlighting wire-array Z-pinches

Data mining to effect of key alloying elements on corrosion resistance of low alloy steels in Sanya seawater environmentAlloying Elements

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Journal of Materials Science & technology 2021年第5期64卷 222-232页

作者： Xin Wei Dongmei Fu Mindong Chen Wei Wu Dequan Wu Chao Liu School of Automation and electrical engineering University of Science and Technology BeijingBeijing100083China Beijing engineering Research center of Industrial Spectrum Imaging University of Science and Technology BeijingBeijing 100083China SINOPEC Research Institute of Safety engineering Qingdao266100China Beijing advanced Innovation center for Materials Genome engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083China

In this paper,the relationship model between seawater environment,chemical composition and corrosion potential of low alloy steel is established and the distribution of corrosion potential of low alloy steel with changes in key alloying elements is *** research was carried out with the following steps:Firstly,the relationship model between corrosion potential of low alloy steel and its influencing factors was established by data dimension reduction and artificial neural network(ANN).Secondly,key alloying elements of experimental steels were selected out by Pearson correlation analysis,then the corrosion resistance element model was visualized to show the effect of key alloying elements on corrosion potential of low alloy ***,corrosion potential of low alloy steel with the change of key alloying elements was classified and visualized by classification *** mining results can reflect the validity of the proposed mining methods to a certain extent and provide an intuitive data basis for the development of high-quality and low-cost low alloy steels.

关键词： Low alloy steel Corrosion potential Key alloying elements Corrosion-resistant alloy Artificial neural network Data-driven model

Conical tank level control using fractional order PID controllers： a simulated and experimental study

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Control Theory and technology 2016年第4期14卷 369-384页

作者： Cristian JAUREGUI Manuel A. DUARTE-MERMOUD Rodrigo OROSTICA Juan Carlos TRAVIESO-TORRES Orlando BEYTIA electrical engineering department and advanced mining technology center Universidad de Chile Av. Tupper 2007 Casilla 412-3 Santiago Chile Industrial Technologies department Technological Faculty Universidad de Santiago de Chile Av. El Belloto 3735 Santiago Chile

In this paper, simulated and experimental results on the conical tank level control are presented. PI/PID controllers of integer order （IO） as well as of fractional order （FO） are studied and compared. The tuning parameters are obtained first by using root locus （RL） and Ziegler and Nichols methods, for comparison purposes. Next, particle swarm optimization （PSO） is employed to determine the optimal controllers＇ parameters using as fitness function the integral of the absolute value of tracking error （IAE）. From the experimental results it is concluded that PI/FOPI are the controllers presenting the lowest IAE indexes, whereas PID/FOPID controllers present the lowest energy consumption by the control signal.

关键词： Level control conical tank PID control fractional PID control experimental control

A Combinational Perspective in Stimulating Cooperation in Mobile Ad Hoc Networks

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Journal of Computer Science & technology 2011年第2期26卷 256-268页

作者： Mahshid Rahnamay-Naeini Masoud Sabaei department of Computer engineering and Information technology Amirkabir University of Technology department of electrical and Computer engineering University of New Mexico

In wireless ad hoc networks cooperation among nodes cannot always be assumed since nodes with limited resources and different owners are capable of making independent decisions. Cooperation problems in topology control and packet forwarding tasks have been mostly studied separately but these two tasks are not independent. Considering a joint cooperation problem by taking into account dependencies between tasks will result in more reliable and efficient networks. In this paper topology control definition is extended to cover cooperation problem in both packet forwarding and topology control in a single problem. In this definition nodes have to adjust their transmission power and decide on their relay role. This paper models the interactions of nodes as a potential game with two-dimensional utility function. The presented model, named TCFORCE （Topology Control packet FORwarding Cooperation Enforcement）, preserves the network connectivity and reduces the energy consumption by providing cooperative paths between all pairs of nodes in the network.

关键词： game theory non-cooperative packet forwarding topology control wireless ad hoc networks

Dynamic failure risk of coal pillar formed by irregular shape longwall face:A case study

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International Journal of mining Science and technology 2018年第5期28卷 775-781页

作者： Yixin Zhao Hao Wang Shimin Liu Zonglong Mu Zhiguo Lu Beijing Key Laboratory for Precise mining of Intergrown Energy and Resources School of Resources and Safety Engineering China University of Mining & Technology department of Energy and Mineral engineering G3 Center and EMS Energy Institute Pennsylvania State University University Park School of Mines China University of Mining & Technology

Irregular shape workface would result in the presence of coal pillar, which leads to high stress concentration and possibly induces coal bumps. In order to study the coal bump mechanism of pillars, static and dynamic stress overlapping(SDSO) method was proposed to explain the impacts of static stress concentration and tremors induced by mining activities. The stress and deformation in surrounding rock of mining face were analyzed based on the field case study at 1303 workface in Zhaolou Coal Mine in *** results illustrate that the surrounding rock of a workface could be divided into four different zones,i.e., residual stress zone, stress decrease zone, stress increase zone and original stress zone. The stress increase zone is prone to failure under the SDSO impact loading conditions and will provide elastic energy for inducing coal bump. Based on the numerical modelling results, the evolution of static stress in coal pillar as the size of gob increasing was studied, and the impact of dynamic stress was investigated through analyzing the characteristics of tremor activities. The numerical results demonstrate the peak value of vertical stress in coal pillar rises from about 30 MPa with mining distance 10 m to 52.6 MPa with mining distance 120 m, and the location of peak stress transfers to the inner zone of coal pillars as the workface moves forward. For the daily tremor activities, tremors with high energy released indicate high dynamic stress disturbance on the surrounding rock, therefore, the impact of dynamic stressing is more serious during workface extension period because the tremor frequency and average energy after workface extension are higher than those before the workface extension.

关键词： Coal bump Coal pillar Tremor Irregular shape longwall face Static and dynamic stress overlapping

A review of offshore wind farm layout optimization and electrical system design methods

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Journal of Modern Power Systems and Clean Energy 2019年第5期7卷 975-986页

作者： Peng HOU Jiangsheng ZHU Kuichao MA Guangya YANG Weihao HU Zhe CHEN center of electrical engineering Technical University of DenmarkLyngbyDenmark department of Energy technology Aalborg UniversityAalborgDenmark School of Mechanical and electrical engineering University of Electronic Science and Technology of ChinaChengduChina

There is more wind with less turbulence offshore compared with an onshore case,which drives the development of the offshore wind farm *** a huge amount of money is required for constructing an offshore wind farm,many types of research have been done on the optimization of the offshore wind farm with the purpose of either minimizing the cost of energy or maximizing the total energy *** are several factors that have an impact on the performance of the wind farm,mainly the energy production of wind farm which is highly decided bythe wind condition of construction area and micro-siting of wind turbines(WTs),as well as the initial investment which is influenced by both the placement of WTs and the electrical system design,especially the scheme of cable connection *** this paper,a review of the state-of-the-art researches related to the wind farm layout optimization as well as electrical system design including cable connection scheme optimization is *** most significant factors that should be considered in the optimization work of the offshore wind farm is highlighted after reviewing the latest works,and the future needs are specified.

关键词： Energy production Wake modelling Wind farm layout optimization Cable connection scheme optimization Offshore wind farm

Surface engineering for high stable lithium-rich manganese-based cathode materials

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Chinese Chemical Letters 2023年第6期34卷 588-593页

作者： Miaomiao Zhou Jianjun Zhao Xiaodong Wang Ji Shen Wenhao Tang Yirui Deng Ruiping Liu School of Chemical&Environmental engineering China University of Mining and Technology(Beijing)Beijing 100083China State Key Laboratory of Chemical Resources engineering Beijing Advanced Innovation Center for Soft Matter Science and EngineeringCollege of ChemistryBeijing University of Chemical TechnologyBeijing 100029China department of Materials Science and engineering China University of Mining&Technology(Beijing)Beijing 100083China

Lithium-rich manganese-based material shows great potential as the high specific cathode materials due to its low cost,environmental friendliness,high operating voltage and simple preparation ***,the poor capacity retention and cycling performance caused by its unstable structure during cycling restrict the *** this work,Li_(1.2)Ni_(0.16)Mn_(0.56)Co_(0.08)O_(2)was synthesized utilizing a Coprecipitation method and different amount of La(PO_(3))_(3)(La(PO_(3))_(3)=2 wt%,4 wt%and 6 wt%)was selected as the coating layer to resolve the above *** the calcination process,La(PO_(3))_(3)reacts with impurities such as Li OH and Li_(2)CO_(3)on the lithium-rich surface to reduce the residual lithium on the surface,thus improving the interfacial stability,slowing down the corrosion of the electrolyte,and finally enhancing its electrochemical *** cathode materials coated with 4%of La(PO_(3))_(3)showed the best electrochemical performance in terms of capacity retention and cycling performance compared to the pristine *** high initial discharge capacity of 214.21 m Ah/g and capacity retention of 94.2%after 100 cycles at 0.1 C can be *** work provides an effective strategy to protect the cathode from corrosion and will promote its further practical applications in high specific Li-ion batteries.

关键词： Li-rich layered oxide Li-ion batteries La(PO_(3))_(3)coating Electrochemical performance Structure stability

Cell-protecting regeneration from anode carbon deposition using in situ produced oxygen and steam:A combined experimental and theoretical study

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Journal of Materials Science & technology 2018年第12期34卷 2375-2383页

作者： Zongying Han Zhibin Yang Minfang Han Union Research center of Fuel Cell School of Chemical and Environmental EngineeringChina University of Mining and Technology department of Energy and Power engineering Tsinghua University College of Chemical and Environmental engineering Shandong University of Science and Technology

Carbon deposition is a primary concern during the operation of solid oxide fuel cells（SOFCs） fueled with hydrocarbon fuels, leading to cell degradation and even cell damage. Carbon elimination is expected to be a promising approach to prolong cell life. This work reports on a combined experimental and theoretical investigation of cell regeneration from anode carbon deposition of tubular SOFCs fabricated by phase-inversion and co-sintering techniques. The as-prepared cell exhibits a maximum power density of 0.20 W cm;at 800 ℃ fueling with wet CH;, but fails to stable operation due to severe carbon *** on thermodynamic predictions, a successive cell-protecting regeneration process is proposed to eliminate deposited carbon without oxidizing Ni catalysts, during which CH;and H;fuels are provided in circulation. Through a total of 35 cycling tests, cell performance can always successfully restore to the initial *** possible carbon elimination mechanism is investigated in detail based on thermodynamic and first-principle calculations. The feasibility of carbon elimination using in situ produced oxygen or steam through electrochemical reaction has been revealed, providing a novel continuous operation mode for hydrocarbon-based SOFCs.

关键词： Solid oxide fuel cells Carbon deposition Cell regeneration Carbon elimination First-principle