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Active splitting strategy searching approach based on MISOCP with consideration of power island stability

Journal of Modern Power Systems and Clean Energy 2019年第3期7卷 475-490页

作者： yifan zhou Wei HU Yong MIN Le ZHENG Department of Electrical Engineering Tsinghua UniversityBeijing100084China Department of Cardiothoracic Surgery Stanford UniversityStanfordUSA

Active splitting control utilizes real-time decision and system-level splitting to prevent cascading blackouts and to maintain power supply under severe disturbances. Splitting strategy searching(SSS) is one of the most crucial issues in active splitting control for deciding‘‘where to split’’. SSS determines the splitting surface in real time to properly divide the asynchronous generators into isolated islands with an optimal control effect. In this paper, an SSS approach that focuses on island stability is presented. The proposed SSS approach is designed to ensure a rational stability margin and regulation ability on each island during and after the transient process of system splitting. This method includes the active/reactive power flow feasibility constraints and voltage/angle stability constraints in the steady state as well as the frequencyresponse capability constraints in the transient process. By considering the island stability constraints in the SSS, the proposed approach can avoid the splitting strategies with poor stability performance. Therefore, the major advantage of the proposed approach is that it can ensure better island static and transient stability during and after the splitting control. In addition, the entire model is formulated as a mixed-integer second-order cone programming(MISOCP)model. Thus, it can be rapidly solved by using commercial optimization solvers. Numerical simulations of a realistic provincial power system in central China demonstrate thevalidity of the proposed approach and the necessity of considering the island stability issues.

关键词： Splitting strategy searching(SSS) Mixed-integer second-order cone programming(MISOCP) Controlled islanding Static stability margin Transient stability Power system

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Wind power forecasting errors modelling approach considering temporal and spatial dependence

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Journal of Modern Power Systems and Clean Energy 2017年第3期5卷 489-498页

作者： Wei HU Yong MIN yifan zhou Qiuyu LU The State Key Lab of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijingChina Power Dispatch Control Centre of Guangdong Power Grid Corporation GuangzhouChina

The uncertainty of wind power forecasting significantly influences power systems with high percentage of wind power generation. Despite the wind power forecasting error causation, the temporal and spatial dependence of prediction errors has done great influence in specific applications, such as multistage scheduling and aggregated wind power integration. In this paper, Pair-Copula theory has been introduced to construct a multivariate model which can fully considers the margin distribution and stochastic dependence characteristics of wind power forecasting errors. The characteristics of temporal and spatial dependence have been modelled, and their influences on wind power integrations have been *** comparisons indicate that the proposed model can reveal the essential relationships of wind power forecasting uncertainty, and describe the various dependences more accurately.

关键词： Pair-Copula Wind power forecasting Temporal dependence Spatial dependence Wind power integrations

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Epidemiology,pathogenesis,and management of coronavirus disease 2019-associated stroke

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Frontiers of Medicine 2023年第6期17卷 1047-1067页

作者： Lu Liu Chenxia zhou Huimin Jiang Huimin Wei yifan zhou Chen zhou Xunming Ji Department of Neurology Xuanwu HospitalCapital Medical UniversityBeijing 100032China Neurology and Intracranial Hypertension and Cerebral Venous Disease Center National Health Commission of ChinaXuanwu HospitalCapital Medical UniversityBeijing 100032China Beijing Institute of Brain Disorders Capital Medical UniversityBeijing 100069China Beijing Advanced Innovation Center for Big Data-Based Precision Medicine School of Biological Science and Medical EngineeringBeihang UniversityBeijing 100191China Department of Neurology Beijing Shjitan HospitalCapital Medical UniversityBeijing 100038China Department of Neurosurgery Xuanwu HospitalCapital Medical UniversityBeijing 100032China

The coronavirus disease 2019(COVID-19)epidemic has triggered a huge impact on healthcare,socioeconomics,and other aspects of the world over the past three *** increasing number of studies have identified a complex relationship between COVID-19 and stroke,although active measures are being implemented to prevent disease *** COVID-19 may be associated with an increased risk of stroke and increase the rates of disability and mortality,posing a serious challenge to acute stroke diagnosis,treatment,and *** review aims to provide an update on the influence of COVID-19 itself or vaccines on stroke,including arterial stroke(ischemic stroke and hemorrhagic stroke)and venous stroke(cerebral venous thrombosis).Additionally,the neurovascular mechanisms involved in SARS-CoV-2 infection and the clinical characteristics of stroke in the COVID-19 setting are *** on vaccinations,potential therapeutic approaches,and effective strategies for stroke management has been highlighted.

关键词： SARS-CoV-2 ischemic stroke stroke hemorrhagic stroke cerebral venous thrombosis vaccination

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Gravity compensation method via magnetic quasi-zero stiffness combined with a quasi-zero deformation control strategy

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Science China(Technological Sciences) 2022年第8期65卷 1738-1748页

作者： zhou Rui zhou yifan CHEN XueDong HOU WeiJie WANG Chang WANG Hao JIANG Wei State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin Institute of Aerospace Mechanical and Electrical EquipmentTianjin 300301China Institute of Artificial Intelligence Huazhong University of Science and TechnologyWuhan 430074China

Gravity compensation refers to the creation of a constant supporting force to fully or partly counteract the gravitational force for ground verification to simulate the spacecraft dynamics in outer space with zero-or micro-gravity. Gravity compensation is usually implemented via a very low stiffness suspension/supporting unit, and a servo system in series is adopted to extend the simulation range to hundreds of millimeters. The error of suspension force can be up to tens of Newton due to the contact/friction in the suspension/supporting unit and the error of the force/pressure sensor. It has become a bottleneck for the ground verification of spacecraft guidance, navigation, and control systems with extreme requirements, such as tons of payload and fine thrust in sub-Newtons. In this article, a novel gravity compensation method characterized by quasi-zero stiffness plus quasi-zero deformation(QZS-QZD) is proposed. A magnetic negative stiffness spring in parallel with positive springs and aerostatic bearing is adopted to form a QZS supporting unit, and disturbance forces, such as contact or friction, can be eliminated. The deformation of the QZS supporting unit is measured via a displacement sensor, and the QZD control strategy is applied to guarantee the force error of gravity compensation to be less than sub-newtons and irrelevant to the payload. The principle of gravity compensation with QZS-QZD is analyzed, and performance tests on a prototype are carried out. The results show that when the spacecraft moves smoothly, the absolute force error is less than 0.5 N, the relative error of gravity compensation is less than 0.1%, and when collisions with other objects occur, the relative errors are 0.32% and 0.65%. The proposed method can significantly improve the gravity compensation accuracy in comparison with conventional approaches.

关键词： gravity compensation zero-gravity ground verification quasi-zero stiffness quasi-zero deformation

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GhATL68b regulates cotton fiber cell development by ubiquitinating the enzyme required for β-oxidation of polyunsaturated fatty acids

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Plant Communications 2024年第10期5卷 139-153页

作者： Xin Li Gai Huang yifan zhou Kun Wang Yuxian Zhu College of Life Sciences Wuhan UniversityWuhan 430072China Institute for Advanced Studies Wuhan UniversityWuhan 430072China Hubei Hongshan Laboratory Wuhan 430072China TaiKang Center for Life and Medical Sciences Wuhan UniversityWuhan 430072China State Key Laboratory of Plant Genomics and National Center for Plant Gene Research Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing 100101China

E3 ligases are key enzymes required for protein ***,we identified a C3H2C3 RING domaincontaining E3 ubiquitin ligase gene named *** is preferentially and highly expressed in developing cotton fiber cells and shows greater conservation in plants than in animals or *** four orthologous copies of this gene in various diploid cottons and eight in the allotetraploid *** were found to have originated from a single common ancestor that can be traced back to Chlamydomonas reinhardtii at about 992 million years *** variations in the GhATL68b promoter regions of ***,***,***,and *** are correlated with significantly different methylation *** CRISPR-Cas9 knockout cotton lines exhibit significant reductions in fiber quality traits,including upper-half mean length,elongation at break,uniformity,and mature fiber *** vitro ubiquitination and cell-free protein degradation assays revealed that GhATL68b modulates the homeostasis of 2,4-dienoyl-CoA reductase,a rate-limiting enzyme for theβ-oxidation of polyunsaturated fatty acids(PUFAs),via the ubiquitin proteasome *** cells harvested from these knockout mutants contain significantly lower levels of PUFAs important for production of glycerophospholipids and regulation of plasma membrane *** fiber growth defects of the mutant can be fully rescued by the addition of linolenic acid(C18:3),the most abundant type of PUFA,to the ovule culture *** experimentally characterized C3H2C3 type E3 ubiquitin ligase involved in regulating fiber cell elongation may provide us with a new genetic target for improved cotton lint production.

关键词： Gossypium hirsutum E3 ligases polyunsaturated fatty acids β-oxidation fiber development

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Noisy-intermediate-scale quantum power system state estimation

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iEnergy 2024年第3期3卷 135-141页

作者： Fei Feng Peng Zhang yifan zhou Yacov A.Shamash Department of Engineering SUNY Maritime CollegeBronxNY 10465USA Department of Electrical and Computer Engineering Stony Brook UniversityStony BrookNY 11794-2350USA

Quantum power system state estimation(QPSSE)offers an inspiring direction for tackling the challenge of state estimation through quantum ***,the current bottlenecks originate from the scarcity of practical and scalable QPSSE methodologies in the noisy intermediate-scale quantum(NISQ)*** paper devises a NISQ−QPSSE algorithm that facilitates state estimation on real NISQ *** new contributions include:(1)A variational quantum circuit(VQC)-based QPSSE formulation that empowers QPSSE analysis utilizing shallow-depth quantum circuits;(2)A variational quantum linear solver(VQLS)-based QPSSE solver integrating QPSSE iterations with VQC optimization;(3)An advanced NISQ-compatible QPSSE methodology for tackling the measurement and coefficient matrix issues on real quantum computers;(4)A noise-resilient method to alleviate the detrimental effects of noise *** encouraging test results on the simulator and real-scale systems affirm the precision,universal-ity,and scalability of our QPSSE algorithm and demonstrate the vast potential of QPSSE in the thriving NISQ era.

关键词： Quantum computing state estimation variational quantum linear solver noisy-intermediate-scale quantum(NISQ)era

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Dynamic Comprehensive Assessment of Power Development Based on Provincial Data

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CSEE Journal of Power and Energy Systems 2020年第3期6卷 672-680页

作者： Wei Hu Qiuting Guo yifan zhou Yi Kang Huanshuai Bing Dan Bao State Key Lab of Power Systems the Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Central Southern China Electric Power Design Institute China Power Engineering Consulting Group CorporationWuhan 430071China Northeast Branch State Grid Corporation of ChinaShenyang 110180China

Dynamic comprehensive assessment of regional power industry development levels is of paramount importance for understanding the development characteristics and potential of the local power industry.A tri-level evaluation index system is established,describing five aspects of the local power industry development level,specifically,the coordination degree between the power industry and economy/energy,power generation,power consumption,power supply and development potential.A combination of information entropy and the analytic hierarchy process(AHP)is used to establish a static evaluation model,and a blend of subjective opinions and objective data information is then *** aggregating the static evaluation model for each time period based on a time-ordered weighting vector calculated using time-ordered information entropy,a dynamic comprehensive evaluation model of power industry development level is *** considering provincial data from China recorded during 2007 to 2016 as the sample set,through synchronic and diachronic comparisons of the evaluation results,the differences,characteristics and potential of local power industry development in China are explored.

关键词： Analytic hierarchy process development level of power electric industry dynamic comprehensive assessment information entropy

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High entropy materials based electrocatalysts for water splitting:Synthesis strategies,catalytic mechanisms,and prospects

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Nano Research 2023年第4期16卷 4411-4437页

作者： Xiumin Li yifan zhou Changrui Feng Ran Wei Xiaogang Hao Keyong Tang Guoqing Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Graduate School of Sustainable Community Studies Hirosaki University1-BunkyochoHirosaki 036-8560Japan Graduate School of Science and Technology Hirosaki University3-BunkyochoHirosaki 036-8561Japan Department of Chemical Engineering Taiyuan University of TechnologyTaiyuan 030024China Energy Conversion Engineering Laboratory Institute of Regional InnovationHirosaki University3-BunkyochoHirosaki 036-8561Japan

Among various electrocatalysts,high entropy materials(HEMs)have attracted great attention due to the distinctive designing concept and unique properties with captivating electrocatalytic activity and *** date,HEMs have been a new family of advanced electrocatalysts in the research field of water *** this work,the structural features and synthesis strategies of high entropy catalysts are reviewed,especially,their performances for catalyzing hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in water electrolysis are presented,in which the crucial roles of structure,composition,multisites synergy,and“four core effects”for enhancing catalytic activity,stability,and resistance of electrochemical corrosion are ***,the design tactics,main challenges,and future prospects of HEM-based electrocatalysts for HER and OER are *** is expected to provide valuable information for the development of low-cost efficient HEM-based electrocatalysts in the field of water electrolysis.

关键词： water electrolysis high entropy electrocatalysts synthesis strategies catalytic mechanisms prospects

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In vitro corrosion properties of HTHEed Mg-Zn-Y-Nd alloy microtubes for stent applications:Influence of second phase particles and crystal orientation

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Journal of Magnesium and Alloys 2022年第5期10卷 1286-1295页

作者： Peihua Du Di Mei Tsuyoshi Furushima Shijie Zhu Liguo Wang yifan zhou Shaokang Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Henan Key Laboratory of Advanced magnesium Alloys Zhengzhou 450002China Key Laboratory of Advanced Materials Processing and Mold Ministry of Education Zhengzhou 450002China Department of Mechanical and Biofunctional Systems Institute of Industrial ScienceThe University of Tokyo4-6-1KomabaMeguroTokyo 153-8505Japan Magnesium Innovation Centre-MagIC Institute of Materials ResearchHelmholtz-Zentrum GeesthachtGeesthacht 21502Germany

Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and ***,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer from a rapid corrosion rate and severe localized corrosion,which is limiting their widespread *** solve the problem of uneven degradation of stents,a HTHE(long-time and high-temperature heat treatment,large-reduction-ratio hot extrusion)process is used to manufacture Mg-Zn-Y-Nd alloy microtubes in this *** heat treatment is to dissolve alloying elements and reduce the size of SPPs,and the hot extrusion is to acquire fine-grained and strongly textured *** microstructural characterization shows that coarse second phases in as-cast alloy are refined and uniformly distributed in matrix of *** hot extrusion,microtubes show strong texture with basal plain oriented parallel to the longitudinal section(LS).The corrosion testing indicates that severe localized corrosion occurs on the cross section(CS)while localized corrosion is alleviated on the *** on the different corrosion properties of the LS and CS,HTHEed microtubes are promising for solving the problems of rapid corrosion rate and severe localized corrosion of Mg alloy stents.

关键词： Mg-Zn-Y-Nd alloy Microtubes Heat treatment Hot extrusion Corrosion properties Cardiovascular stent

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Microstructural evolution and its influence on mechanical and corrosion behaviors in a high-Al/Zn containing duplex Mg-Li alloy after friction stir processing

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Journal of Materials Science & Technology 2024年第17期184卷 245-255页

作者： Yixing Zhu Mengran zhou Yingxin Geng Shun Zhang Tongzheng Xin Gaoqiang Chen yifan zhou Xiaoyu zhou Ruizhi Wu Qingyu Shi State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084China Key Laboratory of Superlight Materials&Surface Technology(Ministry of Education) Harbin Engineering UniversityHarbin 150001China Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China Beijing North Vehicle Group Corporation Beijing 100072China

Ultralight Mg-Li alloys offer promising applications across various ***-Li alloys enriched with Al and Zn hold theoretical potential for achieving excellent mechanical strength and corrosion ***,the structural and performance characteristics of such Mg-Li alloys,particularly after thermo-mechanical processing,remain inadequately explored and *** study investigated the mi-crostructural evolution of a Mg-9Li-5Al-4Zn alloy after friction stir processing and its consequent effects on the mechanical and corrosion *** grain size of the alloy was effectively refined and sta-bilized during friction stir processing at various heat *** yield strength of the alloy increased by 86.4%after friction stir processing under the highest heat input condition,which was attributed to fine grain strengthening,solid solution strengthening and dispersion ***,the alloy ex-perienced a slight decrease in elongation after the friction stir *** alloy subjected to friction stir processing with the highest heat input exhibited a minimal corrosion current density of 6.10×10^(−6) A/cm^(2),which was only 25%of the base *** enhanced anti-corrosion properties can be attributed to the dispersion and distribution of precipitated particles induced by friction stir processing,which hin-dered the micro-galvanic corrosion and promoted the generation of a compact surface film,leading to minimal and uniform *** investigation can be significant for understanding the metallurgical mechanisms and performance evolution of Mg-Li alloys during thermomechanical processes.

关键词： Mg-Li-Al-Zn alloy Friction stir processing Microstructure evolution Thermal-mechanical stability Corrosion behavior

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