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High Impedance Fault Detection Based on Attention Mechanism and Object Identification

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 197-207页

作者： Yongjie zhang Xiaojun Wang Yiping Luo Dahai zhang Sohrab Mirsaeidi Jinghan he School of Electrical Engineering Beijing Jiaotong UniversityBeijing 100044China

Detection of high impedance faults(HIFs)has been traditionally a main challenge in the protection of distribution systems,since they do not generate enough current to be reliably detected by conventional over-current ***-based methods are alternative HIF detection methods which avoid threshold settings by training a classification or regression ***,most of them lack interpretability and are not compatible with various distribution *** paper proposes an object detection-based HIF detection method,which has higher visualization and can be easily applied to different ***,based on the analysis of HIFs,a Butterworth band-pass filter is designed for HIF harmonic feature ***,based on the synchronized data provided by distribution-level phasor measurement units,global HIF feature gray-scale images are formed through combining the topology information of the distribution *** further enhance the feature information,a locally excitatory globally inhibitory oscillator region attention mechanism(LEGIO-RAM)is proposed to highlight the critical feature regions and inhibit useless and fake ***,an object detection network based You Only Look Once(YOLO)v2 is established to achieve fast HIF detection and section *** obtained results from the simulation of the proposed approach on three different distribution networks and one realistic distribution network verify that the proposed method is highly effective in terms of reliability and generalization.

关键词： Attention mechanism distribution-level phasor measurement units high impedance faults object detection

3D-Printed Flat-Bone-Mimetic Bioceramic Scaffolds for Cranial Restoration

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Research 2024年第3期6卷 259-272页

作者： Yihang zhang Fupo he Qiang zhang Haotian Lu Shengtao Yan Xuetao Shi School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006P.R.China School of Materials Science and Engineering South China University of TechnologyGuangzhou 510641P.R.China Peking Union Medical College Graduate School Bejing 100730P.R.China Department of Emergency China-Japan Friendship HospitalBeijing 100029P.R.China.

The limitations of autologous bone grafts necessitate the development of advanced biomimetic biomaterials for efficient cranial defect *** cranial bones are typical flat bones with sandwich structures,consisting of a diploe in the middle region and 2 outer compact *** this study,we originally developed 2 types of flat-bone-mimeticβ-tricalcium phosphate bioceramic scaffolds(Gyr-Comp and Gyr-Tub)by high-precision vat-photopolymerization-based 3-dimensional *** scaffolds had 2 outer layers and an inner layer with gyroid pores mimicking the diploe *** outer layers of Gyr-Comp scaffolds simulated the low porosity of outer tables,while those of Gyr-Tub scaffolds mimicked the tubular pore structure in the tables of flat *** Gyr-Comp and Gyr-Tub scaffolds possessed higher compressive strength and noticeably promoted in vitro cell proliferation,osteogenic differentiation,and angiogenic activities compared with conventional scaffolds with cross-hatch *** implantation into rabbit cranial defects for 12 weeks,Gyr-Tub achieved the best repairing effects by accelerating the generation of bone tissues and blood *** work provides an advanced strategy to prepare biomimetic biomaterials that fit the structural and functional needs of efficacious bone regeneration.

关键词： rabbit tables outer

Obituary:*** zhang(1963-2023)-A scientist focused on toxins and their underlying mechanisms to decipher human diseases

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Zoological Research 2024年第1期45卷 230-232页

作者： Wenhui Lee ren Lai the Key Laboratory of Bioactive Peptides of Yunnan Province Engineering Laboratory of Peptides of Chinese Academy of SciencesKIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common DiseasesNational Resource Centre for Non-Human PrimatesKunming Primate Research CentreNational Research Facility for Phenotypic&Genetic Analysis of Model Animals(Primate Facility)Sino-African Joint Research CentreNew Cornerstone Science InstituteKunming Institute of ZoologyChinese Academy of SciencesKunmingYunnan 650107China

*** zhang was born on 9 July 1963 in Kunming,Yunnan,China,during a tumultuous period which he often *** his life,he harbored a steadfast belief in using knowledge to unravel the mysteries of human *** educational journey was marked by frequent changes in schools due to his parents’occupational ***,despite these challenges,he consistently displayed diligence and was admitted to the East China University of Science and Technology,Shanghai,after completing high school in *** remained an active and loyal member of the School of Biotechnology at the university.

关键词： admitted harbor mechanisms

Single Ti atoms coupled with Ti-O clusters enable low temperature hydrogen cycling by sodium alanate

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Rare Metals 2024年第6期43卷 2671-2681页

作者： Zhuang-he ren Xin zhang Wen-Xuan zhang Zhen-Guo Huang Li-Mei Yang Ya-Xiong Yang Zheng-Long Li Juan Li Wen-Ping Sun Ming-Xia Gao Hong-Ge Pan Yong-Feng Liu State Key Laboratory of Silicon and Advanced Semiconductor Materials Zhejiang UniversityHangzhou 310027China School of Materials Science and Engineering Zhejiang UniversityHangzhou 310058China School of Civil&Environmental Engineering.University of Technology Sydney Sydney2007 NSWAustralia Institute of Science and Technology for New Energy Xi'an Technological UniversityXi'an 710021China College of Materials Science and Engineering Zhejiang University of TechnologyHangzhou 310014China

Ti-based catalysts are known to improve the hydrogen storage performance of NaAlH4by facilitating the dissociation/recombination of H-H and Al-H *** catalytic activity of metallic Ti species strongly depends on its particle size and *** clusters and even single atoms are therefore highly desirable,but their controllable fabrication has been highly *** rein,we demonstrate a novel facile sonochemical synthesis of a Ti-O clusters featuring single Ti atom catalyst at room *** reducing TiCl_(4)by MgBu_(2)with ultrasound instead of heating as driving force,numerous single Ti atoms coupled with Ti-O clusters with Ti loading on graphene(Ti_(1)/Ti-O@G)up to 22.6 wt%have been successfully *** prepared Ti_(1)/Ti-O@G contributes high reactivity and superior catalytic activity,therefore enabling full dehydrogenation of NaAlH_(4)at 80℃in thermogravimetric mode and re-hydrogenation at 30℃and 10 MPa with 4.9 wt% H_(2).This fact indicates for the first time that single Ti atom catalyst with high loading is highly effective in catalyzing hydrogen cycling of NaAlH4at remarkably reduced temperatures.

关键词： Hydrogen storage Nanocatalysis Transition metals Single Ti atoms NaAlH_(4)

Effects of projectile parameters on the momentum transfer and projectile melting during hypervelocity impact

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Defence Technology（防务技术） 2024年第2期32卷 89-103页

作者： Wenjin Liu Qingming zhang renrong Long Zizheng Gong ren Jiankang Xin Hu Siyuan ren Qiang Wu Guangming Song State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China Beijing Institute of Spacecraft Environment Engineering China Academy of Space TechnologyBeijing100094China

The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical *** comparing the computation results with the experimental results,the correctness of the calculation and the statistical method of momentum transfer coefficient is *** shapes of aluminum,copper and heavy tungsten alloy projectiles striking aluminum,basalt,and pumice target for impacts up to 10 km/s are *** influence mechanism of the shape of the projectile and projectile/target density on the momentum transfer was *** an increase in projectile density and length-diameter ratio,the energy transfer time between the projectile and targets is *** projectile decelerates slowly,resulting in a larger cratering *** energy consumed by the projectile in the excavation stage increased,resulting in lower mass-velocity of ejecta and momentum transfer *** numerical simulation results demonstrated that for different projectile/target combinations,the higher the wave impedance of the projectile,the higher the initial phase transition velocity and the smaller the mass of phase *** results can provide theoretical guidance for kinetic impactor design and material selection.

关键词： Hypervelocity impact Energy partitioning Impact melting Momentum transfer

A sponge-based iron-tannic-acid hydrogel interface evaporator designed for clean water production

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Science China(Technological Sciences) 2024年第5期67卷 1579-1591页

作者： zhang ZeKun LI ChengLong TAO HuaYu GE Bo zhang YongLe ZHAO LiMin LIU JunChang ren GuiNa zhang ZhaoZhu School of Materials Science and Engineering Liaocheng UniversityLiaocheng252059China School of Environmental and Material Engineering Yantai UniversityYantai264405China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China

Due to the rapid advancement of technologies,there has been a significant increase in the discharge of industrial wastewater,and freshwater is becoming a scarce ***,research on solar evaporators is mainly focused on the efficient production of clean water,with less emphasis on the removal of residual pollutants remaining in the original *** this study,problems,including the difficult recovery of catalyst powder and the difficult removal of floating organic matter are solved by co-depositing low-surface-tension zirconia particles and bismuth tungstate onto the floating *** and melamine sponges were combined to solve the problem that traditional hydrogels lack mechanical *** excellent water-repellent effect can be seen from the contact angle between the liquid globule and canvas/felt,which is greater than 155°.The steam generation rate of the assembled evaporation system is 1.78 kg m^(-2)h^(-1),and its purification efficiency for methyl orange and rhodamine B exceeds 99%.This study presents a novel strategy for treating wastewater contaminated with organic dyes,aiming to solve problems including environmental damage,water pollution,and water scarcity.

关键词： oil removal non-wetting interface

Design,Testing and Control of a Magnetorheological Damper for Knee Prostheses

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Journal of Bionic Engineering 2024年第4期21卷 1788-1800页

作者： Hounan Song Yu Cao Wei Chen Lei ren Yongxin Ma Kunyang Wang Xu Wang Yao zhang Luquan ren Key Laboratory of Bionic Engineering Ministry of EducationJilin UniversityChangchun130022People’s Republic of China Department of Mechanical Aerospace and Civil EngineeringThe University of ManchesterManchesterM139PLUK

This study aims to develop a magnetorheological(MR)damper for semi-active knee prostheses to restore the walking ability of transfemoral *** core dimensions of the MR damper were determined via theoretical magnetic field calculations,and the theoretical relationship between current and joint torque was derived through electromagnetic ***,a physical prototype of the semi-active prosthetic knee equipped with the MR damper was *** on the data obtained from angle sensor,pressure sensor(loadcell),and inertial measurement unit(IMU)on the prosthesis,a matching control algorithm is *** joint torque of the MR damper can be adaptively adjusted according to the walking speed of the amputee,allowing the amputee to realize a natural *** effectiveness of the control program was verified by the ADAMS and MATLAB *** results of the test and simulation show that the MR damper can provide sufficient torque needed for normal human activities.

关键词： Semi-active knee prosthesis Magnetorheological damper Theoretical analysis ADAMS and MATLAB co-simulation

Economic analysis of rooftop photovoltaics system under different shadowing conditions for 20 cities in China

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Building Simulation 2024年第2期17卷 235-252页

作者： Zhiyi ren Yixing Chen Chengcheng Song Mengyue Liu Anni XuQilin zhang College of Civil Engineering Hunan UniversityChangsha410082China Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education Hunan UniversityChangsha410082China

Installing photovoltaic(PV)systems is an essential step for low-carbon *** economics of PV systems are strongly impacted by the electricity price and the shadowing effect from neighboring *** study evaluates the PV generation potential and economics of 20 cities in China under three shadowing ***,the building geometry models under three shadowing conditions for the 20 cities were constructed using ***,60 building models with PV systems and shadows from surrounding buildings were generated by City Buildings,Energy,and Sustainability(CityBES),an open platform,to simulate the PV power ***,the study presented one economic analysis model to evaluate the profitability by combining the market cost of rooftop PV systems and electricity prices in *** economic model included four indicators:payback period(static and dynamic),net present value(NPV),and internal rate of return(IRR).The results show that the reduction of PV power generation ranges from 8.29%to 16.01%under medium shadowing,and experiences a maximum decrease of up to 39.71%under high *** economic analysis shows that almost all the regions show reliable potential,obtaining an IRR higher than the reference value(5%).Nenjiang has the highest economic profit,with the highest NPV(86,181.15 RMB)and IRR(30.14%)under no shadowing among 20 *** also should be mentioned that the alignment between electricity price distribution and the solar power generation curve will directly impact the economic potential of PV systems.

关键词： rooftop photovoltaic system EnergyPlus economic analysis shadowing buildings electric price

Influence of Anteroposterior Symmetrical Aero-Wings on the Aerodynamic Performance of High-Speed Train

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 937-953页

作者： Peiheng he Jiye zhang Lan zhang Jiaqi Wang Yuzhe Ma State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu610031China

The running stability of high-speed train is largely constrained by the wheel-rail coupling relationship,and the continuous wear between the wheel and rail surfaces will profoundly affect the dynamic performance of the *** recent years,under the background of increasing train speed,some scientific researchers have proposed a new idea of using the lift force generated by the aerodynamic wings(aero-wing)installed on the roof to reduce the sprung load of the carriage in order to alleviate the wear and tear of the wheel and *** on the bidirectional running characteristics of high-speed train,this paper proposes a scheme to apply aero-wings with anteroposterior symmetrical cross-sections on the roof of the *** the verification of the wind tunnel experimental data,the relatively better airfoil section and extension formof anteroposterior symmetrical aero-wing is selected respectively in this paper,and the aero-wings are fixedly connected to the roof of the train through the mounting column to conduct aerodynamic simulation *** research shows that:compared with the circular-arc and oval crosssections,this paper believes that the crescent cross-section can form greater aerodynamic lift force in a limited *** factors such as aerodynamic parameters,ground effect,and manufacturing process,this paper proposes to adopt aero-wings with arc type extension form and connect them to the roof of the train through mounting columns with shuttle *** the roof of the train is covered with aero-wings and runs at high speed,the sprung load of the carriages can be effectively ***,there are certain hidden dangers in the tail carriage due to the large amount of lift force,so,the intervention of the aero-wing lifting mechanism is *** the same time,it is necessary to optimize the overall aerodynamic drag force reduction in the followup work.

关键词： Anteroposterior symmetrical aero-wing wheel-rail wear aerodynamic lift force ground effect numerical simulation