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Transient Stability Analysis and Design of VSGs with Different DC-Link Voltage Controllers

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 593-604页

作者： Chao Shen wei Gu Wanxing sheng Keyan Liu School of Electrical Engineering Southeast UniversityNanjingChina Power Distribution Research Department China Electric Power Research InstituteBeijing 100192China

Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.

关键词： DC-link voltage dynamics equal area criterion(eac) transient synchronization stability virtual synchronous generator(VSG)

Streamflow abrupt change and the driving factors in glacierized basins of Tarim Basin,Northwest China

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Advances in Climate Change Research 2024年第1期15卷 75-89页

作者： Cheng-De YANG Min XU Shi-Chang KANG Cong-sheng FU wei zhang Di-Di HU State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Watershed Geographic Sciences Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210000China

A climate transition towards warm-wet conditions in Northwest China has drawn much *** continuous climate change and universal glacier degradation,increasing water-related hazards and vulnerability have become one of the important problems facing the Tarim ***,the impacts of the climate transition on streamflow abrupt change and extreme hydrological events were less discussed,especially in glacial *** the present study,the discharge datasets in four glacial basins of Tarim Basin from 1979 to 2018 were constructed using the GRU-GSWAT+model *** differences in streamflow characteristics,the shift of hydrological extreme pattern,and potential changes of the controlling factors before and after the abrupt changes were *** results indicated that the abrupt change point(ACP)in streamflow occurred in 2000 in the Qarqan River Basin,2002 in the weigan River Basin,and 1994 in the Aksu River Basin and the Yarkant River Basin.A general decrease in streamflow before the ACP has shifted to a notable upward trend in the Qarqan River Basin and the Aksu River Basin,while minor upward fluctuations were observed in other ***,the hydrological characteristics in extreme events vary dramatically before and after the ACPs,characterized by a pronouncing shift from drought-dominant pattern to wet events dominated *** driven climate factors have been altered after the ACPs with notable spatial heterogeneity,in which temperature remained as the dominant role in meltwater-dominated basins while the influence of precipitation has increased after the ACPs,whereas the sensitivity of temperature on streamflow change has been enhanced in basins dominated by precipitation such as the Qarqan River *** to the evident warming-wetting trend and glacier compensation effect,both the inter-annual and intra-annual streamflow fluctuations can be efficiently smoothed in basins with a high glacier area ratio(GAR).These findings provide a

关键词： Abrupt change Streamflow Hybrid model Tarim Basin Glacier

Detection of SARS-CoV-2 based on artificial intelligence-assisted smartphone:A review

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Chinese Chemical Letters 2024年第7期35卷 25-34页

作者： Yunxin Li Jinghui zhang Jisen Chen Feng Zhu Zhiqiang Liu Peng Bao wei Shen sheng Tang School of Environmental and Chemical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China Programme in Emerging Infectious Diseases Duke-NUS Medical SchoolSingapore 169857Singapore

In recent years,the application of smartphone in various fields has received great attention,and it has become a promising tool in virus detection,data processing and data *** the rapid spread of COVID-19 around the world,many traditional detection methods have been combined with smartphone to assist in the analysis and detection of the novel coronavirus(SARS-CoV-2),including electrochemistry,fluorescence and *** the gradual development of artificial intelligence(AI),the combination of AI and smartphone to analyze SARS-CoV-2 was also the focus of *** on the summary of the traditional methods combined with smartphone to detect SARS-CoV-2 virus,in addition to AI-based data processing,AI algorithms are also employed for SARS-CoV-2 detection *** review discussed both strategies and focused on the application of the *** combination of AI algorithm and smartphone to detect SARS-CoV-2 has high accuracy,which is more conducive to meeting the needs of portable *** addition,the classification of SARS-CoV-2 virus samples in biological fluids such as blood and saliva was also ***,this paper briefly discussed the limitations of using smartphone analysis to detect SARS-CoV-2,as well as the prospect and future development of virus *** conclusion,the detection methods based on smartphone and AI algorithms show great potential in the detection of SARS-CoV-2 and can be a valuable complement to traditional analysis methods.

关键词： COVID-19 SARS-CoV-2 virus Detection method Smartphone analysis Artificial intelligence

Robust adaptive radar beamforming based on iterative training sample selection using kurtosis of generalized inner product statistics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 24-30页

作者： TIAN Jing zhang wei School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Electromagnetic Space Security Chengdu 610036China

In engineering application,there is only one adaptive weights estimated by most of traditional early warning radars for adaptive interference suppression in a pulse reputation interval(PRI).Therefore,if the training samples used to calculate the weight vector does not contain the jamming,then the jamming cannot be removed by adaptive spatial *** the weight vector is constantly updated in the range dimension,the training data may contain target echo signals,resulting in signal cancellation *** cope with the situation that the training samples are contaminated by target signal,an iterative training sample selection method based on non-homogeneous detector(NHD)is proposed in this paper for updating the weight vector in entire range *** principle is presented,and the validity is proven by simulation results.

关键词： adaptive radar beamforming training sample selection non-homogeneous detector electronic jamming jamming suppression

Elite Dung Beetle Optimization Algorithm for Multi-UAV Cooperative Search in Mountainous Environments

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Journal of Bionic Engineering 2024年第4期21卷 1677-1694页

作者： Xiaoyong zhang wei Yue The College of Marine Electrical Engineering Dalian Maritime UniversityDalian116026China

This paper aims to address the problem of multi-UAV cooperative search for multiple targets in a mountainous environment,considering the constraints of UAV dynamics and prior environmental ***,using the target probability distribution map,two strategies of information fusion and information diffusion are employed to solve the problem of environmental information inconsistency caused by different UAVs searching different areas,thereby improving the coordination of UAV ***,the task region is decomposed into several high-value sub-regions by using data clustering *** on this,a hierarchical search strategy is proposed,which allows precise or rough search in different probability areas by adjusting the altitude of the aircraft,thereby improving the search ***,the Elite Dung Beetle Optimization Algorithm(EDBOA)is proposed based on bionics by accurately simulating the social behavior of dung beetles to plan paths that satisfy the UAV dynamics constraints and adapt to the mountainous terrain,where the mountain is considered as an obstacle to be ***,the objective function for path optimization is formulated by considering factors such as coverage within the task region,smoothness of the search path,and path *** effectiveness and superiority of the proposed schemes are verified by the simulation.

关键词： Mountainous environment Multi-UAV cooperative search Environment information consistency Elite dung beetle optimization algorithm(EDBOA) Path planning

Evolutionary mechanism and frequency response of graphite electrode at extreme temperatures

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Nano Research 2024年第8期17卷 7283-7289页

作者： Shanpeng Pei Zhiyong zhang Xiuli zhang Yan Liu Xiang Han Linshan Luo Pengfei Su Chaofei Lan wei Huang Ziqi zhang Ming-sheng Wang Songyan Chen Department of Physics Xiamen UniversityXiamen 361005China Shandong Electric Power Engineering Consulting Institute Corporation Jinan 250031China State Key Lab of Physical Chemistry of Solid Surfaces College of MaterialsXiamen UniversityXiamen 361005China School of Semiconductor Science and Technology South China Normal UniversityFoshan 528225China College of Materials Science and Engineering Nanjing Forestry UniversityNanjing 210037China National Key Laboratory of Integrated Circuits and Microsystems Chongqing 400000China

The battery management system is employed to monitor the external temperature of the lithium-ion battery in order to detect any potential ***,this outside–in detection method often suffers from a lag and is therefore unable to accurately predict the battery’s real-time ***,an inside–out frequency response approach is used to accurately monitor the battery’s state at various temperatures in real-time and correlate it with the solid electrolyte interphase(SEI)evolution of the graphite *** SEI evolution at temperatures of−15,25,60,and 90℃exhibits certain regular characteristics with temperature *** a temperature of−15℃,the Li^(+)-solvent interaction of lithium-ion slowed down,resulting in a significant reduction in *** 25℃,a LiF-rich inorganic SEI was identified as forming,which facilitated lithium-ion ***,high temperatures would induce decomposition of lithium hexafluorophosphate(LiPF_(6))and lithium-ion *** the extreme temperature of 90℃,the SEI would be organic-rich,and Li_(x)P_(y)F_(z),a decomposition product of lithium salts,was further oxidized to Li_(x)PO_(y)F_(z),which led to a surge in the charge-transfer resistance at SEI(R_(sei))and a reduction in Coulombic efficiency(CE).This changing relationship can be recorded in real time from the inside out by electrochemical impedance spectroscopy(EIS)*** provides a new theoretical basis for the structural evolution of lithium-ion batteries and the regular characterization of EIS.

关键词： graphite electrode solid electrolyte interphase(SEI)film extreme temperatures frequency response evolutionary mechanism

基于立方星辐射计直接检波系统的毫米波零偏置肖特基二极管检波器设计

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红外与毫米波学报 2022年第1期41卷 285-293页

作者：陈峣张升伟中国科学院国家空间科学中心中国科学院微波遥感技术重点实验室北京100190 中国科学院大学北京100049

基于立方星辐射计直接检波系统,设计并实现了中心频率分别为89 GHz和150 GHz的两款毫米波零偏置肖特基检波器。检波器设计基于ACST的零偏置肖特基二极管。为了获得稳定、优越的性能以及较好的宽带特性,并易于与前级系统集成,更适于立方... 详细信息

基于立方星辐射计直接检波系统,设计并实现了中心频率分别为89 GHz和150 GHz的两款毫米波零偏置肖特基检波器。检波器设计基于ACST的零偏置肖特基二极管。为了获得稳定、优越的性能以及较好的宽带特性,并易于与前级系统集成,更适于立方星辐射计小型化,在直流接地电路与输出电路处采用扇形线结构,并通过一段可调传输线对其端口阻抗进行优化。本文对肖特基二极管及检波器电路结构进行了分析、建模和优化。测试结果表明,W波段检波器在85~95 GHz范围内具有2500 V/W的典型灵敏度,在89 GHz测试的线性度为0.9994。D波段检波器在145~155 GHz范围内的典型灵敏度约为1600 V/W,在150 GHz测试的线性度为0.9992。这些结果验证了改进电路结构在检波器设计上的优越性和在直接检波系统中应用的可行性。

关键词：毫米波检波器零偏置肖特基二极管阻抗匹配

Inter-well internal resonance analysis of rectangular asymmetric cross-ply bistable composite laminated cantilever shell under transverse foundation excitation

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Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1353-1370页

作者： Lele REN wei zhang Yufei zhang State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Department of Mechanics Guangxi UniversityNanning 530004China Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures College of Mechanical EngineeringBeijing University of TechnologyBeijing 100124China

The chaotic dynamic snap-through and complex nonlinear vibrations are investigated in a rectangular asymmetric cross-ply bistable composite laminated cantilever shell,in cases of 1:2 inter-well internal resonance and primary *** transverse foundation excitation is applied to the fixed end of the structure,and the other end is in a free *** first-order approximate multiple scales method is employed to perform the perturbation analysis on the dimensionless two-degree-of-freedom ordinary differential motion control *** four-dimensional averaged equations are derived in both polar and rectangular coordinate *** from the obtained frequency-amplitude and force-amplitude response curves,a detailed analysis is conducted to examine the impacts of excitation amplitude,damping coefficient,and tuning parameter on the nonlinear internal resonance characteristics of the *** nonlinear softening characteristic is exhibited in the upper stable-state,while the lower stable-state demonstrates the softening and linearity *** simulation is carried out using the fourth-order Runge-Kutta method,and a series of nonlinear response curves are *** the excitation amplitude further elucidates the global bifurcation and chaotic dynamic snap-through characteristics of the bistable cantilever shell.

关键词： bistable composite laminated cantilever shell inter-well internal resonance primary resonance chaotic dynamic snap-through complex nonlinear vibration

Proximal Femur Bionic Nail (PFBN): A Panacea for Unstable Intertrochanteric Femur Fracture

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Engineering 2024年第6期37卷 152-158页

作者： Kaixuan zhang wei Chen Yingze zhang School of Medicine Nankai UniversityTianjin 300071China Department of Orthopedic Surgery of Hebei Province The Third Hospital of Hebei Medical UniversityShijiazhuang 050051China Key Laboratory of Biomechanics of Hebei Province Orthopaedic Research Institute of Hebei ProvinceShijiazhuang 050051China National Health Commission(NHC)Key Laboratory of Intelligent Orthopeadic Equipment The Third Hospital of Hebei Medical UniversityShijiazhuang 050051China Chinese Academy of Engineering Beijing 100088China

With the aging population,intertrochanteric femur fracture in the elderly has become one of the most serious public health issues and a hot topic of research in trauma *** to the limitations of internal fixation techniques and the insufficient mechanical design of nails,the occurrence of complications delays patient recovery after surgical *** of a proximal femur bionic nail(PFBN)based on zhang’s N triangle theory provides triangular supporting fixation,which dramatically decreases the occurrence of complications and has been widely used for clinical treatment of unstable intertrochanteric femur fracture *** this work,we developed an equivalent biomechanical model to analyze improvement in bone remodeling of unstable intertrochanteric femur fracture through PFBN *** results show that compared with proximal femoral nail antirotation(PFNA)and InterTan,PFBN can dramatically decrease the maximum strain in the proximal *** on Frost’s mechanostat theory,the local mechanical environment in the proximal femur can be regulated into the medium overload region by using a PFBN,which may render the proximal femur in a state of physiological overload,favoring post-operative recovery of intertrochanteric femur fracture in the *** work shows that PFBN may constitute a panacea for unstable intertrochanteric femur fracture and provides insights into improving methods of internal fixation.

关键词： Intertrochanteric femur fracture Internal fixation Proximal femur bionic nail(PFBN) Biomechanics Bone remodeling