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Research on the Mining Effect of Floor Strata in Deep Coal Seam Mining: A Case Study of #7 Coal Seam at Chazhuang Coal Mine

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IOP Conference Series: Earth and Environmental science 2020年第5期570卷

作者： Wenquan Zhang Xintao Wu Jianli Shao Yanghui Ren Zaiyong Wang College of Energy and Mining Engineering Shandong University of Science and Technology Qingdao 266590 China. State Key Laboratory of Mining Disaster Prevention and Control Shandong University of Science and Technology Qingdao 266590 China. Mining Engineering National Experimental Teaching Demonstration Center Shandong University of Science and Technology Qingdao 266590 China. Central Research Institute China Coal Industry Group Beijing 100020 China

Studying the mining effect of floor strata in deep coal seam mining is beneficial for evaluating and relieving the risk of water inrush from the floor. In addition, such research forms the basis for ensuring the support and stability of roadways and chambers in the lower part of the coal seam. By considering the mining of #7 coal seam in the 7600 deep mining area of the Chazhuang coal mine in Feicheng coalfield as the engineering background, this study analyzes the distribution law of mining abutment pressure and the range of failure depth affected by mining using elastic theory. In addition, the stress, strain, and failure states of the floor rock mass affected by mining are comprehensively simulated and studied using the FLAC3D finite difference software combined with field measurement results of rock movement in the lower roadway of the #7 coal seam. The mining effect of the floor is further compared and studied, providing a scientific reference basis for realizing the safe mining of coal in confined water in the deep lower group of the Feicheng coalfield.

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Optimal Relay Coordination and Communication based Protection for Microgrid

Optimal Relay Coordination and Communication based Protectio...

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IEEE Region 10 Symposium on Technologies for Smart Cities (TENSYMP)

作者： Srinivas, S. T. P. Swarup, K. Shanti National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China Sichuan China Science and Technology on Electronic Information Control Laboratory 29th Research Institute of China Electronics Technology Group Corporation Sichuan China

ISBN: (纸本)9781509062553

Microgrids can be Distributed Generation (DG) supported distribution systems which are operated either intact with the main grid or operated independently. The flexibility in microgrid operation makes its protection more complex. Advanced protection methods involving communication can provide intelligent and smart ways of protection by which digital relays can be made predictive. One of the profound challenges faced by the power engineers in designing a working microgrid system is relay coordination. In a meshed distribution system relay coordination becomes complicated due to bi-directional current flows and inadequate fault currents when microgrid is islanded. This paper takes up the traditional relay coordination problem in microgrid scenario and investigates the performance of conventional and dual setting directional overcurrent relays (CDOCRs and DS-DOCRs) and proposes a communication based protection algorithm to tackle the problems associated with both CDOCRs and DS-DOCRs. Simulation tests are conducted on IEEE 30 bus system. The relay coordination problem is defined as nonlinear optimization problem and solved using Matlab optimization tool box.

关键词： Protection Relay Coordination Directional Over current relays dual setting Microgrids

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Study on the Arsenic Content of Ophiocordyceps sinensis in Sichuan Province

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Medicinal Plant 2018年第1期9卷 47-49页

作者： Yulong CHEN Zhu JIANG Jintao LI Zhiyu SUN Sichuan Academy of Forestry Sciences Beijing Key Laboratory of Environmental and Viral Oncology College of Life Science and BioengineeringBeijing University of Technology State Key Laboratory for Infectious Disease Prevention and Control National Institute for Viral Disease Control and PreventionChinese Center for Disease Control and Prevention

[Objectives] To investigate the characteristics of arsenic content of Ophiocordyceps sinensis in Sichuan Province. [Methods]Using ICP-MS( Inductively Coupled Plasma-Mass Spectrometry),we studied the 30 samples of O. sinensis from 25 places of production in Sichuan Province as well as the arsenic content in the habitat soil. [Results] The arsenic content of O. sinensis in Sichuan Province was0. 62-9. 16 mg/kg; the arsenic content in habitat soil was 3. 93-59. 90 mg/kg. [Conclusions]90% of O. sinensis products from Sichuan Province exceeded the arsenic content limit of 1 mg/kg in the health food,and as a comparison,the arsenic content of samples from Qinghai,Tibet,Gansu was over the limit.

关键词： Ophiocordyceps sinensis Arsenic Sichuan Province

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Correction to: Complete genome analysis of a virulent Vibrio scophthalmi strain VSc190401 isolated from diseased marine fish half-smooth tongue sole, Cynoglossus semilaevis

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BMC microbiology 2020年第1期20卷 375页

作者： Zheng Zhang Yong-Xiang Yu Yin-Geng Wang Xiao Liu Li-Fang Wang Hao Zhang Mei-Jie Liao Bin Li Key Laboratory of Maricultural Organism Disease Control Ministry of Agriculture and Rural Affairs Yellow Sea Fisheries Research Institute Chinese Academic of Fishery Sciences Qingdao Shandong 266071 PR China. zhangzheng@***. Laboratory for Marine Fisheries Science and Food Production Processes Pilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao Shandong 266237 PR China. zhangzheng@***. Key Laboratory of Maricultural Organism Disease Control Ministry of Agriculture and Rural Affairs Yellow Sea Fisheries Research Institute Chinese Academic of Fishery Sciences Qingdao Shandong 266071 PR China. Key Laboratory of Maricultural Organism Disease Control Ministry of Agriculture and Rural Affairs Yellow Sea Fisheries Research Institute Chinese Academic of Fishery Sciences Qingdao Shandong 266071 PR China. wangyg@***. Laboratory for Marine Fisheries Science and Food Production Processes Pilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao Shandong 266237 PR China. wangyg@***. Laboratory for Marine Fisheries Science and Food Production Processes Pilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao Shandong 266237 PR China.

An amendment to this paper has been published and can be accessed via the original article.

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Corrigendum to: Lianhuaqingwen exerts anti-viral and anti-inflammatory activity against novel coronavirus (SARS-CoV-2) [Pharmacol. Res. 156 (2020) 104761]

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Pharmacological research 2021年 174卷 105907页

作者： Li Runfeng Hou Yunlong Huang Jicheng Pan Weiqi Ma Qinhai Shi Yongxia Li Chufang Zhao Jin Jia Zhenhua Jiang Haiming Zheng Kui Huang Shuxiang Dai Jun Li Xiaobo Hou Xiaotao Wang Lin Zhong Nanshan Yang Zifeng State Key Laboratory of Respiratory Disease National Clinical Research Center for Respiratory Disease Guangzhou Institute of Respiratory Health the First Affiliated Hospital of Guangzhou Medical University Guangzhou Guangdong PR China. Hebei University of Chinese Medicine College of Integrated Chinese and Western Medicine China. Technology Centre Guangzhou Customs China. KingMed Virology Diagnostic & Translational Center China. State Key Laboratory of Respiratory Disease National Clinical Research Center for Respiratory Disease Guangzhou Institute of Respiratory Health the First Affiliated Hospital of Guangzhou Medical University Guangzhou Guangdong PR China State Key Laboratory of Quality Research in Chinese Medicine Macau Institute for Applied Research in Medicine and Health Macau University of Science and Technology Taipa Macau China KingMed Virology Diagnostic & Translational Center China. Electronic address: jeffyah@***.

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Fog-assisted multi-user swipt networks: Local computing or offloading

arXiv

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arXiv 2019年

作者： Zheng, Haina Xiong, Ke Fan, Pingyi Zhong, Zhangdui Letaief, Khaled Ben School of Computer and Information Technology Beijing Key Lab of Traffic Data Analysis and Mining Beijing Jiaotong University Beijing China Beijing Key Laboratory of Security and Privacy in Intelligent Transportation Beijing Jiaotong University Beijing100044 China National Laboratory for Information Science and Technology Department of Electronic Engineering Tsinghua University Beijing100084 China State Key Lab of Rail Traffic Control and Safety Beijing Engineering Research Center of High-speed Railway Broadband Mobile Communications Beijing Jiaotong University Beijing100044 China Clear Water Bay Hong Kong

This paper investigates a fog computing-assisted multi-user simultaneous wireless information and power transfer (SWIPT) network, where multiple sensors with power splitting (PS) receiver architectures receive information and harvest energy from a hybrid access point (HAP), and then process the received data by using local computing mode or fog offloading mode. For such a system, an optimization problem is formulated to minimize the sensors' required energy while guaranteeing their required information transmissions and processing rates by jointly optimizing the multi-user scheduling, the time assignment, the sensors' transmit powers and the PS ratios. Since the problem is a mixed integer programming (MIP) problem and cannot be solved with existing solution methods, we solve it by applying problem decomposition, variable substitutions and theoretical analysis. For a scheduled sensor, the closed-form and semi-closedform solutions to achieve its minimal required energy are derived, and then an efficient multi-user scheduling scheme is presented, which can achieve the suboptimal user scheduling with low computational complexity. Numerical results demonstrate our obtained theoretical results, which show that for each sensor, when it is located close to the HAP or the fog server (FS), the fog offloading mode is the better choice;otherwise, the local computing mode should be selected. The system performances in a frame-by-frame manner are also simulated, which show that using the energy stored in the batteries and that harvested from the signals transmitted by previous scheduled sensors can further decrease the total required energy of the sensors. Copyright © 2019, The Authors. All rights reserved.

关键词： Energy harvesting

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Observation of Fano resonance in photoluminescence of a two-dimensional magnetic semiconductor

arXiv

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arXiv 2019年

作者： Gu, Pingfan Tan, Qinghai Wan, Yi Li, Ziling Peng, Yuxuan Lai, Jiawei Ma, Junchao Yao, Xiaohan Yuan, Kai Sun, Dong Peng, Bo Zhang, Jun Ye, Yu State Key Laboratory for Artificial Microstructure & Mesoscopic Physics Nanooptoelectronics Frontier Center of the Ministry of Education School of Physics Peking University Beijing100871 China State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors & Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing100049 China International Center of Quantum Matter Beijing100871 China Collaborative Innovation Center of Quantum Matter Beijing100871 China National Engineering Research Center of Electromagnetic Radiation Control Materials State Key Laboratory of Electronic Thin Films and Integrated Devices School of Microelectronics and Solid State Electronics University of Electronic Science and Technology of China Chengdu610054 China Beiing Academy of Quantum Information Science Beijing100193 China

Quantum interference gives rise to the asymmetric Fano resonance line shape when the final states of an electronic transition follows within a continuum of states and a discrete state, which has significant applications in optical switching and sensing. The resonant optical phenomena associated with Fano resonance have been observed by absorption spectra, Raman spectra, transmission spectra, etc., but have rarely been reported in photoluminescence (PL) spectroscopy. In this work, we performed spectroscopic studies on layered chromium thiophosphate (CrPS4), a promising ternary antiferromagnetic semiconductor with PL in near-infrared wavelength region and observed Fano resonance when CrPS4 experiences phase transition into the antiferromagnetic state below Néel temperature (38 K). The photoluminescence of the continuum states results from the d band transitions localized at Cr3+ ions, while the discrete state reaches saturation at high excitation power and can be enhanced by the external magnetic field, suggesting it is formed by an impurity level from extra atomic phosphorus. Our findings provide insights into the electronic transitions of CrPS4 and their connection to its intrinsic magnetic properties. Copyright © 2019, The Authors. All rights reserved.

关键词： Chromium compounds

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Recent progress in covalent organic framework thin films: fabrications, applications and perspectives

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Chemical Society reviews 2019年第2期48卷 488-516页

作者： Han Wang Zhuotong Zeng Piao Xu Lianshan Li Guangming Zeng Rong Xiao Zhiyong Tang Danlian Huang Lin Tang Cui Lai Danni Jiang Yang Liu Huan Yi Lei Qin Shujing Ye Xiaoya Ren Wangwang Tang College of Environmental Science and Engineering Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University) Ministry of Education Changsha 410082 P. R. China. zgming@***. Department of Dermatology Second Xiangya Hospital Central South University Changsha 410011 P. R. China. xiaorong65@***. CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellent in Nanoscience National Center for Nanoscience and Technology Beijing 100190 P. R. China. zytang@***.

As a newly emerging class of porous materials, covalent organic frameworks (COFs) have attracted much attention due to their intriguing structural merits (e.g., total organic backbone, tunable porosity and predictable structure). However, the insoluble and unprocessable features of bulk COF powder limit their applications. To overcome these limitations, considerable efforts have been devoted to exploring the fabrication of COF thin films with controllable architectures, which open the door for their novel applications. In this critical review, we aim to provide the recent advances in the fabrication of COF thin films not only supported on substrates but also as free-standing nanosheets via both bottom-up and top-down strategies. The bottom-up strategy involves solvothermal synthesis, interfacial polymerization, room temperature vapor-assisted conversion, and synthesis under continuous flow conditions; whereas, the top-down strategy involves solvent-assisted exfoliation, self-exfoliation, mechanical delamination, and chemical exfoliation. In addition, the applications of COF thin films including energy storage, semiconductor devices, membrane-separation, sensors, and drug delivery are summarized. Finally, to accelerate further research, a personal perspective covering their synthetic strategies, mechanisms and applications is presented.

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Research on Topology and Modulation control Method of a Novel Three-Level Current-Fed DCDC Converter

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IOP Conference Series: Materials science and Engineering 2019年第4期612卷

作者： Kai Ji Tingyang Chen Wenfeng Long Jinping He National Key Laboratory of Science and Technology on Vessel Integrated Power System Wuhan Institute of Marine Electric Propulsion Wuhan China

Multilevel current source converter has the benefits of high output capacity, low current switching stress and low harmonic or ripple content. This paper presents a new topology of three-level current-fed DC/DC converter for superconducting magnetic energy storage application. In this topology, a superconducting inductance acting as a constant current source and a shunt inductance acts as current divider ensure current flows through the power switch components equally to generate immediate level of current. A novel kind of pulse width modulation (PWM) switching strategy for the current instantaneous control of the current source converter was proposed. The modulation switching strategy proposed is able to effectively control the DC current output of the converter. Also, due to the both of proposed topology and control method are quite a simple, it can be easily realized in the practice. Simulation results prove the feasibility and validity of the proposed topology and modulation strategy

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Influence of installation error on roundness error measurement

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IOP Conference Series: Materials science and Engineering 2019年第3期612卷

作者： Xuelei Chen Yifan Dai Hao Hu Guipeng Tie Chaoliang Guan Laboratory of Science and Technology on Integrated Logistics Support National University of Defense Technology Changsha 410073 China College of Intelligence Science National University of Defense Technology Changsha 410073 China Hu'nan Key Laboratory of Ultra-precision Machining Technology Changsha 410073 China

The installation tilt causes the actual measured circular contour to be an elliptical contour [1], and the installation eccentricity causes the sampled points uneven [2], which can both affect the measurement accuracy of the roundness error [3, 4]. The tilt and eccentricity error must be separate from the measured data when measuring the cylindrical workpiece roundness error with a cylindricity measuring instrument to obtain the true contour information of the cylindrical workpiece itself. In this paper, the mathematical models of the workpiece installation tilt and eccentricity are established based on the least square roundness error evaluation algorithm. The influence of the workpiece installation tilt and eccentricity on the roundness error measurement are simulated by MATLAB, and an actual measurement is analysed. The results show that after leveling and centering the workpiece, the influence of the tilt and eccentricity error of the workpiece installation on roundness error measurement can be neglected when the Taylor565H type cylindricity measuring instrument is used for micron order roundness error measurement.

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