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Microgrid Fault Detection Method Coordinated with a Sequence Component Current-Based Fault Control Strategy

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Protection and Control of Modern Power Systems 2024年第1期9卷 81-93页

作者： Zihao Wang Longhua mu Tongji University ShanghaiChina College of Electronics and Information Engineering Tongji UniversityShanghai 201804China

The fault characteristics of microgrids are affected by the penetration of inverter-interfaced distributed generators(IIDGs).It makes conventional protection schemes no longer *** different grid codes in different countries,IIDGs need to adopt different positive-sequence low-voltage ride-through(LVRT)control strategies during ***,conventional protection schemes have to be modified according to the specific microgrid structure and the IIDGs’LVRT *** order to adapt to different grid codes,a sequence component current-based fault control strategy and a coordinated microgrid fault detection method are proposed in this *** fault control strategy of IIDGs comprehensively considers the coordination between voltage support and fault characteristics generation,where the sequence currents are controlled *** positive-sequence current control strategy aims at supporting the microgrid voltage,whereas the negative-sequence current control strategy aims at generating or enhancing specific fault *** on the proposed fault control strategy,the grid-feeding IIDGs can be equivalent to current sources and generate or enhance the negative-sequence fault characteristics in the equivalent additional networks of negative-sequence *** fault feeder can then be accurately located by analyzing the phase relationship between the negative-sequence fault components of voltage and current phasors.A coor-dinated microgrid fault detection method based on the fault control strategy of IIDGs is *** proposed fault control method makes the fault component protection principle applicable to all types of faults under any operational modes of ***,the correctness and effectiveness of the proposed coordinated fault control and protection strategy are verified in PSCAD/EMTDC.

关键词： fault applicable generating

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关于加快我国科技型中小企业上市融资的思考

特区经济 2010年第12期 120-122页

作者：苏宗睦浙江财经学院数学与统计学院浙江杭州310018

企业是自主创新的主体,只有建立起一大批优质的科技型企业才能推动我国产业结构调整和升级的顺利实施。本文首先分析了国内科技型中小企业的发展状况,并着重指出融资难问题已成为制约科技企业做大做强的瓶颈因素,之后运用SWOT分析模型... 详细信息

企业是自主创新的主体,只有建立起一大批优质的科技型企业才能推动我国产业结构调整和升级的顺利实施。本文首先分析了国内科技型中小企业的发展状况,并着重指出融资难问题已成为制约科技企业做大做强的瓶颈因素,之后运用SWOT分析模型详细研究了科技型中小企业在国内上市融资的优势、劣势,以及面临的机遇和威胁,论文最后提出了改革我国新股发行审核制度、完善上市公司监管体系和拓宽融资渠道三条针对性的建议。

关键词：科技型中小企业创业板直接融资自主创新

High-Order Two-Scale Asymptotic Paradigm for the Elastodynamic Homogenization of Periodic Composites

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Acta Mechanica Solida Sinica 2024年第1期37卷 124-138页

作者： Wei-Zhi Luo mu He Liang Xia Qi-Chang He State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China Laboratoire Modélisation et Simulation multi-Echelle MSME UMR 8208 CNRSUniversite Gustave Eiffel77454 Marne-la-ValléeFrance

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable,which offers an approximate framework for the asymptotic homogenization analysis of the motion ***,in this framework,the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order *** such a context,a compact,fast,and accurate asymptotic paradigm is *** work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be ***,the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor,which is demonstrated by representative one-and two-dimensional *** numerical results show that(1)the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites,(2)the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation,and(3)the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results.

关键词： Composites Homogenization Asymptotic analysis Dynamics Dispersion

Stochastic and Distributed Optimal Energy Management of Active Distribution Networks Within Integrated Office Buildings

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 504-517页

作者： Zening Li su su Xiaolong Jin Mingchao Xia Qifang Chen Koji Yamashita National Active Distribution Network Technology Research Center Beijing Jiaotong UniversityBeijing 100044China Key Laboratory of Smart Grid of Ministry of Education Tianjin UniversityTianjin 300072China Electrical and Computer Engineering University of California RiversideCA92521USA.

This paper proposes a stochastic and distributed optimal energy management approach for active distribution networks(ADNs)within office *** proposed approach aims at scheduling office buildings fitted with heating ventilation and air conditioning(HVAC)systems,and electric vehicle(EV)charging piles,to participate in the ADN ***,an energy management approach for the ADN with aggregated office buildings is *** the ADN optimization model is formulated considering the detailed building thermal dynamics and the mobile behaviors of ***,to consider un-certainties of photovoltaic(PV)power,scenario-based stochastic programming is integrated into the ADN optimization *** further realize the stochastic energy management of the ADN within office buildings in a distributed manner,the alternating direction method of multipliers(ADMM)is used to solve the ADN optimization *** original ADN optimization problem is divided into the network-side and the building-side sub-problems to effectively protect the privacy of the ADN and the office ***,the ADN optimization model incorporating office buildings is validated in the winter by numerical *** addition,the impacts of comfort temperature range and expected state of charge(SOC)at departure are *** Terms—ADN,EV,HVAC system,Office building,Stochastic and distributed energy management.

关键词： ADN EV HVAC system Office building Stochastic and distributed energy management

Vermicompost:In situ retardant of antibiotic resistome accumulation in cropland soils

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Journal of Environmental Sciences 2024年第7期141卷 277-286页

作者： Meirui mu Fengxia Yang Bingjun Han Guisheng Tian Keqiang Zhang Agro-Environmental Protection Institute Ministry of Agriculture and Rural AffairsTianjin 300191China Key Laboratory of Low-carbon Green Agriculture in North China Ministry of Agriculture and Rural Affairs P.R.ChinaBeijing 10083China Wuxue City Agriculture and Rural Bureau Wuhan 435400China

The dissemination of antibiotic resistance genes(ARGs)in soil has become a global environmental *** is gaining prominence in agricultural practices as a soil amendment to improve soil ***,its impact on soil ARGs remains unclear when it occurs in *** comprehensively explored the evolution and fate of ARGs and their hosts in the field soil profiles under vermicompost application for more than *** application increased several ARG loads in soil environment but decreased the high-risk bla-ARGs(bla_(ampC),bla_(NDM),and bla_(GES-1))by log(0.04-0.43).ARGs in soil amended with vermicompost primarily occurred in topsoil(approximately 1.04-fold of unfertilized soil),but it is worth noting that their levels in the 40-60 cm soil layer were the same or even less than in the unfertilized *** microbial community structure changed in soil profiles after vermicompost *** application altered the microbial community structure in soil profiles,showing that the dominant bacteria(i.e.,Proteobacteria,Actinobacteriota,Firmicutes)were decreased 2.62%-5.48%with the increase of soil depth.A network analysis further revealed that most of ARG dominant host bacteria did not migrate from surface soil to deep *** particular,those host bacteria harboring high-risk bla-ARGs were primarily concentrated in the surface *** study highlights a lower risk of the propagation of ARGs caused by vermicompost application and provides a novel approach to reduce and relieve the dissemination of ARGs derived from animals in agricultural production.

关键词： Vermicompost application Antibiotic resistance genes Vertical migration Soil profile Agricultural soils

Numerical simulation of microwave-induced cracking and melting of granite based on mineral microscopic models

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1512-1524页

作者： Xiaoli su Diyuan Li Junjie Zhao Mimi Wang Xing su Aohui Zhou School of Resources and Safety Engineering Central South UniversityChangsha 410083China

This study introduces a coupled electromagnetic–thermal–mechanical model to reveal the mechanisms of microcracking and mineral melting of polymineralic rocks under microwave *** tests validate the rationality of the proposed *** microscopic mineral sections into the granite model for simulation shows that uneven temperature gradients create distinct molten,porous,and nonmolten zones on the fracture ***,the varying thermal expansion coefficients and Young's moduli among the minerals induce significant thermal stress at the mineral *** and biotite with higher thermal expansion coefficients are subjected to compression,whereas plagioclase with smaller coefficients experiences tensile *** the molten zone,quartz undergoes transgranular cracking due to theα–βphase *** local high temperatures also induce melting phase transitions in biotite and *** numerical study provides new insights into the distribution of thermal stress and mineral phase changes in rocks under microwave irradiation.

关键词： microwave numerical modeling microcracking phase change granite

Measurement of acceleration and angular velocity of particles during a 3D silo discharge

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Particuology 2024年第9期92卷 61-71页

作者： Tongtong mu Yiming Li Quan Chen Ran Li Hui Yang College of Medical Instrument Shanghai University of Medicine and Health SciencesShanghai201318China School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai200093China

Accurate measurement of the three-dimensional(3D)movement of discrete particles is crucial for comprehending complex granular rheology in *** this paper,the acceleration and angular velocity of particles in 3D silos are measured by using a spherical detector based on inertial technology and magnetic positioning *** acceleration of particles is the largest in the center of silos,which suggest that the resistance generated by friction and extrusion is the ***,the angular velocity distribution follows lognormal function except for particles near the *** correlation between acceleration and angular velocity is opposite in different flow *** reveals for the first time that the extent to which the resultant force on the particles affects their rotational motion is related to the flow *** results have practical significance for regulating the granular flow pattern and optimizing the structural design of silos.

关键词： Granularflow Silo Angular velocity Acceleration

UNIFORM ERROR BOUNDS OF A CONSERVATIVE COMPACT FINITE DIFFERENCE METHOD FOR THE QUANTUM ZAKHAROV SYSTEM IN THE suBSONIC LIMIT REGIME

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Journal of Computational Mathematics 2024年第1期42卷 289-312页

作者： Gengen Zhang Chunmei su School of Mathematics and Statistics Yunnan UniversityKunming 650504China Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084China

In this paper,we consider a uniformly accurate compact finite difference method to solve the quantum Zakharov system(QZS)with a dimensionless parameter 0<ε≤1,which is inversely proportional to the acoustic *** the s... 详细信息

In this paper,we consider a uniformly accurate compact finite difference method to solve the quantum Zakharov system(QZS)with a dimensionless parameter 0subsonic limit regime,i.e.,when 0sults are reported to verify the error behavior.

关键词： Quantum Zakharov system subsonic limit Compact finite difference method Uniformly accurate Error estimate

Hybrid Block Diagonalization Precoding for multi-User Weighted sum-Rate Maximization

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China Communications 2024年第8期21卷 127-141页

作者： su Xiaofeng Jiang Yi Key Laboratory for Information Science of Electromagnetic Waves(MoE) Department of Communication Science and EngineeringFudan UniversityShanghai 200433China

This paper studies large-scale multi-input multi-output(MIMO)orthogonal frequency division multiplexing(OFDM)communications in a broadband frequency-selective channel,where a massive MIMO base station(BS)communicates with multiple users equipped with *** develop a hybrid precoding design to maximize the weighted sum-rate(WSR)of the users by optimizing the digital and the analog precoders *** the digital part,we employ block-diagonalization to eliminate inter-user interference and apply water-filling power allocation to maximize the *** the analog part,the optimization of the PSN is formulated as an unconstrained problem,which can be efficiently solved by a gradient descent *** results show that the proposed block-diagonal hybrid precoding algorithm can outperform the existing works.

关键词： block-diagonal gradient descent hybrid precoding iterative optimization MIMO-OFDM multi-user water-filling power allocation weighted sum-rate maximization