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Small-signal Stability Criteria in Power Electronics-dominated Power Systems:A Comparative Review

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1003-1018页

作者： Qifan chen Siqi Bu Chi yung Chung Department of Electrical and Electronic Engineer The Hong Kong Polytechnic UniversityHong KongChina Department of Electrical and Electronic Engineering Shenzhen Research InstituteCentre for Grid ModernisationInternational Centre of Urban Energy NexusCentre for Advances in Reliability and SafetyResearch Institute for Smart Energyand Policy Research Centre for Innovation and TechnologyThe Hong Kong Polytechnic UniversityHong KongChina

To tackle emerging power system small-signal stability problems such as wideband oscillations induced by the large-scale integration of renewable energy and power electronics,it is crucial to review and compare existing small-signal stability analysis *** this basis,guidance can be provided on determining suitable analysis methods to solve relevant small-signal stability problems in power electronics-dominated power systems(PEDPSs).Various mature methods have been developed to analyze the small-signal stability of PEDPSs,including eigenvalue-based methods,Routh stability criterion,Nyquist/Bode plot based methods,passivity-based methods,positive-net-damping method,lumped impedance-based methods,bifurcation-based methods,*** this paper,the application conditions,advantages,and limitations of these criteria in identifying oscillation frequencies and stability margins are reviewed and compared to reveal and explain connections and discrepancies among ***,efforts are devoted to mathematically proving the equivalence between these small-signal stability ***,the performance of these criteria is demonstrated and compared in a 4-machine 2-area power system with a wind farm and an IEEE 39-bus power system with 3 wind farms.

关键词： Impedance-based method oscillation analysis power electronic converter power electronics-dominated power system renewable power generation small-signal stability

A Blade Altering Toolbox for Automating Rotor Design Optimization

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Communications on Applied Mathematics and Computation 2024年第1期6卷 688-704页

作者： Akiva Wernick jen-Ping chen Mechanical and Aerospace Engineering The Ohio State University201 W.19th Ave.ColumbusOH43210USA

The Blade Altering Toolbox(BAT)described in this paper is a tool designed for fast reconstruction of an altered blade geometry for design optimization *** BAT algorithm is capable of twisting a given rotor’s angle of attack and stretching the chord length along the span of the *** test cases were run using the BAT’s *** BAT code’s twisting,stretching,and mesh reconstruction capabilities proved to be able to handle reasonably large geometric alterations to a provided input rotor *** test examples showed that the toolbox’s algorithm could handle any stretching of the blade’s chord as long as the blade remained within the original bounds of the unaltered *** algorithm appears to fail when the net twist angle applied the geometry exceeds approximately 30 degrees,however this limitation is dependent on the initial geometry and other input ***,the algorithm is a very powerful tool for automating a design optimization procedure.

关键词： Mesh reconstruction Mesh alteration Rotor alteration Design optimization

Regulation of PM_(2.5)on mitochondrial damage in H9c2 cells through miR-421/SIRT3 pathway and protective effect of miR-421 inhibitor and resveratrol

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Journal of Environmental Sciences 2024年第4期138卷 288-300页

作者： Shanshan chen Wenqi chen Zhiping Li Jianwei Yue Ken Kin Lam yung Ruijin Li Institute of Environmental Science Shanxi UniversityTaiyuan 030006China Institute of Judicial Identification Techniques for Environmental Damage Shanxi University and Shanxi Unisdom Testing Technology Co.Ltd.Taiyuan 030006China Department of Biology Hong Kong Baptist UniversityHong KongChina Shanxi Yellow River Laboratory Taiyuan 030006China

Fine particulate matter(PM_(2.5))exposure is associated with cardiovascular disease(CVD)morbidity and *** are sensitive targets of PM_(2.5),and mitochondrial dysfunction is closely related to the occurrence of *** epigenetic mechanism of PM_(2.5)-triggered mitochondrial injury of cardiomyocytes is *** study focused on the mi R-421/SIRT3 signaling pathway to investigate the regulatory mechanism in cardiac mitochondrial dynamics imbalance in rat H9c2 cells induced by PM_(2.5).Results illustrated that PM_(2.5)impaired mitochondrial function and caused dynamics homeostasis ***,PM_(2.5)up-regulated mi R-421 and down-regulated SIRT3 gene expression,along with decreasing p-FOXO3a(SIRT3 downstream target gene)and p-Parkin expression and triggering abnormal expression of fusion gene OPA1 and fission gene ***,mi R-421 inhibitor(mi R-421i)and resveratrol significantly elevated the SIRT3 levels in H9c2 cells after PM_(2.5)exposure and mediated the expression of SOD2,OPA1 and Drp1,restoring the mitochondrial morphology and *** suggests that mi R-421/SIRT3 pathway plays an epigenetic regulatory role in mitochondrial damage induced by PM_(2.5)and that mi R-421i and resveratrol exert protective effects against PM_(2.5)-incurred cardiotoxicity.

关键词： Fine particulate matter Rat H9c2 cells Mitochondrial damage MiR-421 SIRT3 Resveratrol

Sampling-efficient path planning and improved actor-critic-based obstacle avoidance for autonomous robots

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Science China(Information Sciences) 2024年第5期67卷 197-214页

作者： Yefeng YANG Tao HUANG Tianqi WANG Wenyu YANG Han chen Boyang LI Chih-yung WEN Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic University Center for Control Theory and Guidance Technology Harbin Institute of Technology School of Engineering The University of Newcastle Research Center for Unmanned Autonomous Systems The Hong Kong Polytechnic University

Autonomous robots have garnered extensive utilization in diverse fields. Among the critical concerns for autonomous systems, path planning holds paramount importance. Notwithstanding considerable efforts in its development over the years, path planning for autonomous systems continues to grapple with challenges related to low planning efficiency and inadequate obstacle avoidance response in a timely *** study proposes a novel and systematic solution to the path planning problem within intricate office buildings. The solution consists of a global planner and a local planner. To handle the global planning aspect, an adaptive clustering-based dynamic programming rapidly exploring random tree(ACDP-RRT) algorithm is proposed. ACDP-RRT effectively identifies obstacles on the map by leveraging geometric *** obstacles are then represented as a collection of sequentially arranged convex polygons, optimizing the sampling region and significantly enhancing sampling efficiency. For local planning, a network decoupling actor-critic(ND-AC) algorithm is employed. The proposed ND-AC simplifies the local planner design process by integrating planning and control loops into a neural network(NN) trained via an end-to-end model-free deep reinforcement learning(DRL) framework. Moreover, the adoption of network decoupling(ND) techniques leads to an improved obstacle avoidance success rate when compared to conventional actor-critic(AC)-based methods. Extensive simulations and experiments are conducted to demonstrate the effectiveness and robustness of the proposed approach.

关键词： rapidly exploring random tree (RRT) adaptive clustering network decoupling actor critic (AC) path planning

Highly Accurate Golden Section Search Algorithms and Fictitious Time Integration Method for Solving Nonlinear Eigenvalue Problems

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1317-1335页

作者： Chein-Shan Liu Jian-Hung Shen Chung-Lun Kuo yung-Wei chen Center of Excellence for Ocean Engineering Taiwan Ocean UniversityKeelung202301TaiwanChina Department of Marine Engineering Taiwan Ocean UniversityKeelung202301TaiwanChina

This study sets up two new merit functions,which are minimized for the detection of real eigenvalue and complex eigenvalue to address nonlinear eigenvalue *** each eigen-parameter the vector variable is solved from a nonhomogeneous linear system obtained by reducing the number of eigen-equation one less,where one of the nonzero components of the eigenvector is normalized to the unit and moves the column containing that component to the right-hand side as a nonzero input vector.1D and 2D golden section search algorithms are employed to minimize the merit functions to locate real and complex ***,the real and complex eigenvectors can be computed very accurately.A simpler approach to the nonlinear eigenvalue problems is proposed,which implements a normalization condition for the uniqueness of the eigenvector into the eigenequation *** real eigenvalues can be computed by the fictitious time integration method(FTIM),which saves computational costs compared to the one-dimensional golden section search algorithm(1D GSSA).The simpler method is also combined with the Newton iterationmethod,which is convergent very *** the proposed methods are easily programmed to compute the eigenvalue and eigenvector with high accuracy and efficiency.

关键词： Nonlinear eigenvalue problem quadratic eigenvalue problem two new merit functions golden section search algorithm fictitious time integration method

Automatic fovea detection and choroid segmentation for choroidal thickness assessment in optical coherence tomography

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International Journal of Ophthalmology(English edition) 2024年第10期17卷 1763-1771页

作者： chen Yu Lin Hung Ju chen Yi Kit Chan Wei Ping Hsia Yu Len Huang Chia jen Chang Department of Ophthalmology Taichung Veterans General HospitalTaichung 407TaiwanChina Department of Computer Science Tunghai UniversityTaichung 407TaiwanChina

AIM:To develop an automated model for subfoveal choroidal thickness(SFCT)detection in optical coherence tomography(OCT)images,addressing manual fovea location and choroidal contour ***:Two procedures were proposed:defining the fovea and segmenting the *** localization from B-scan OCT image sequence with three-dimensional reconstruction(LocBscan-3D)predicted fovea location using central foveal depression features,and fovea localization from two-dimensional en-face OCT(LocEN-2D)used a mask region-based convolutional neural network(Mask R-CNN)model for optic disc detection,and determined the fovea location based on optic disc relative *** segmentation also employed Mask ***:For 53 eyes in 28 healthy subjects,LocBscan-3D’s mean difference between manual and predicted fovea locations was 170.0μm,LocEN-2D yielded 675.9μ***-2D performed better in non-high myopia group(P=0.02).SFCT measurements from Mask R-CNN aligned with manual ***:Our models accurately predict SFCT in OCT ***-3D excels in precise fovea localization even with high ***-2D shows high detection rates but lower accuracy especially in the high myopia *** both models offers a robust SFCT assessment approach,promising efficiency and accuracy for large-scale studies and clinical use.

关键词： subfoveal choroidal thickness optical coherence tomography automatic foveal detection automatic choroid segmentation

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Profile of *** chen

Science China(Life Sciences) 2024年第10期67卷 2062-2063页

作者： chen, Songlin Yellow Sea Fisheries Res Inst Qingdao Peoples R China

For decades,*** has been engaged in fish germplasm preservation,sex control and research focusing on molecular breeding for disease *** discovered the first sex-specific molecular marker of fish(chen et al.,2007),deciphered the first fish genome(Chinese tongue sole)in China,revealed the sex determination mechanism in fish(chen et al.,2014),and created molecular sex control *** also discovered the molecular mechanism of metamorphosis in flatfish(Shao et al.,2017)and developed China's first fish disease-resistant breeding gene chip,“YUXIN No.1”.

关键词： technology breeding

Effect of Reclamation on the Groundwater-Lake Water Interaction in chen Lake

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Journal of Earth Science 2024年第3期35卷 1083-1086页

作者： Kun Lei Teng Ma Liuzhu chen Zhenxing Li Yu chen School of Environmental Studies State Key Laboratory of Biogeology and Environmental GeologyChina University of GeosciencesWuhan 430078China

0 INTRODUCTION To relieve the short supply of suitable land for residing,cultivating,and commerce,it is accepted to reclaim land from lakes,river estuaries,and coastal regions in many countries(Mancini et al.,2020).The large-scale reclamation activities have an irreversible effect on the mico-geomorphology and hydrodynamic system of seasonally flooded areas(Zhang et al.,2019;Yu et al.,2018).For example,coastal regions reclaimed extended the groundwater flow paths,as well as created groundwater level rise,resulting in water-logging in the reclaimed area(Hu et al.,2008).Similar changes in groundwater flow systems may alter groundwater-lake water interactions,and it can ultimately affect the water cycle in the lake ***,such detailed studies are presently *** addition,natural exchanges between the lake and groundwater systems can be strongly affected by physical hydrological processes(Javadzadeh et al.,2020),chemical properties(Kamtchueng et al.,2015),and bioto behavior(Hancock et al.,2005).

关键词： groundwater coastal logging

Meridional deflection of global eddy propagation derived from tandem altimetry: Mechanism and implication

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Science China Earth Sciences 2024年第3期67卷 811-825页

作者： Ge chen Xiaoyan chen Frontiers Science Center for Deep Ocean Multispheres and Earth System School of Marine TechnologyOcean University of ChinaQindao 266100China Laboratory for Regional Oceanography and Numerical Modeling Laoshan LaboratoryQindao 266237China

A common view on meridional deflection of eddy propagation is poleward for cyclones and equatorward for anticyclones. This widely accepted polarity-sensitive pattern has been increasingly undermined given that it is systematically violated on both zonal and regional scales as recently reported. Here, we approach the problem by exploring these violations in terms of eddy effects of spatiotemporal geostrophy, thermal fading, and flow dragging, yielding the following main conclusions.(1) The polarity-dependent deflection discrepancy is a pseudo feature resulting from a biased fit to the normalized eddy tracks which are spatially asymmetric(though azimuthally symmetric) between the two signs;Instead, the primary pattern of eddy deflection appears to be geographically correlated and polarity independent.(2) Geostrophic adjustment plays a critical role in defining the meridional movement of an eddy. Specifically, a consistent poleward(equatorward) trajectory bending of spatially(temporally) ageostrophic eddies is observed irrespective of their polarity.(3) The mechanism of eddy deflection is also determined by its zonal propagation direction. Westward propagating eddies are substantially affected by thermal fading, while opposite ones by flow dragging. A realistic and comprehensive understanding of eddy deflection mechanisms serves as a significant contribution to the prediction of eddy trajectory, and the protection of ocean environment.

关键词： Mesoscale eddies Eddy propagation Eddy meridional deflection Satellite observation Geostrophic adjustment