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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

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

Performance Prediction Based Workload Scheduling in Co-Located Cluster

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 2043-2067页

作者： Dongyang Ou Yongjian ren Congfeng Jiang School of Computer Science and Technology Hangzhou Dianzi UniversityHangzhou310018China

Cloud service providers generally co-locate online services and batch jobs onto the same computer cluster,where the resources can be pooled in order to maximize data center resource *** to resource competition between batch jobs and online services,co-location frequently impairs the performance of online *** study presents a quality of service(QoS)prediction-based schedulingmodel(QPSM)for *** performance prediction of QPSM consists of two parts:the prediction of an online service’s QoS anomaly based on XGBoost and the prediction of the completion time of an offline batch job based on ***-line service QoS anomaly prediction is used to evaluate the influence of batch jobmix on on-line service performance,and batch job completion time prediction is utilized to reduce the total waiting time of batch *** the same number of batch jobs are scheduled in experiments using typical test sets such as CloudSuite,the scheduling time required by QPSM is reduced by about 6 h on average compared with the first-come,first-served strategy and by about 11 h compared with the random scheduling *** with the non-co-located situation,QPSM can improve CPU resource utilization by 12.15% and memory resource utilization by 5.7% on *** show that the QPSM scheduling strategy proposed in this study can effectively guarantee the quality of online services and further improve cluster resource utilization.

关键词： Co-located cluster workload scheduling online service batch jobs data center

A Comprehensive Overview of the neural Mechanisms of Light Therapy

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neuroscience Bulletin 2024年第3期40卷 350-362页

作者： Xiaodan Huang Qian Tao Chaoran ren Guangdong-Hongkong-Macao Institute of CnS Regeneration Ministry of Education CNS Regeneration Collaborative Joint LaboratoryJinan UniversityGuangzhou 510632China Psychology Department School of MedicineJinan UniversityGuangzhou 510632China

Light is a powerful environmental factor influencing diverse brain *** evidence supports the beneficial effect of light therapy on several diseases,including depression,cognitive dysfunction,chronic pain,and sleep ***,the precise mechanisms underlying the effects of light therapy are still not well *** this review,we critically evaluate current clinical evidence showing the beneficial effects of light therapy on *** addition,we introduce the research progress regarding the neural circuit mechanisms underlying the modulatory effects of light on brain functions,including mood,memory,pain perception,sleep,circadian rhythm,brain development,and metabolism.

关键词： Light therapy neural circuit Mood Cognition Pain Sleep Development Metabolism

A Hybrid Feature Fusion Traffic Sign Detection Algorithm Based on YOLOv7

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Computers, Materials & Continua 2024年第7期80卷 1425-1440页

作者： Bingyi ren Juwei Zhang Tong Wang School of Mechanical Engineering Henan University of Science and TechnologyLuoyang471000China School of Information Engineering Henan University of Science and TechnologyLuoyang471000China School of Electronic Information Zhengzhou Institute of Aeronautical Industry ManagementZhengzhou450046China Henan Province new Energy Vehicle Power Electronics and Power Transmission Engineering Research Center Luoyang471000China

Autonomous driving technology has entered a period of rapid development,and traffic sign detection is one of the important *** target detection networks are difficult to adapt to scenarios where target sizes are seriously imbalanced,and traffic sign targets are small and have unclear features,which makes detection more ***,we propose aHybrid Feature Fusion Traffic Sign detection algorithmbased onYOLOv7(HFFTYOLO).First,a self-attention mechanism is incorporated at the end of the backbone network to calculate feature interactions within scales;Secondly,the cross-scale fusion part of the neck introduces a bottom-up multi-path fusion *** reuse paths at the end of the neck,paying particular attention to cross-scale fusion of highlevel *** addition,we found the appropriate channel width through a lot of experiments and reduced the superfluous *** terms of training,a newregression lossCMPDIoUis proposed,which not only considers the problem of loss degradation when the aspect ratio is the same but the width and height are different,but also enables the penalty term to dynamically change at different ***,our proposed improved method shows excellent results on the TT100K *** with the baseline model,without increasing the number of parameters and computational complexity,AP0.5 and AP increased by 2.2%and 2.7%,respectively,reaching 92.9%and 58.1%.

关键词： Small target detection YOLOv7 traffic sign detection regression loss

Experiment and Analysis of Compatibility between new Phase Change Mixed Molten Salt and 316L Stainless Steel

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Journal of Thermal Science 2024年第6期33卷 2259-2273页

作者： ren Chenxing ZHEnG Chenghang GAO Xiang State Key Laboratory of Clean Energy Utilization Zhejiang University Institute of Carbon neutrality Zhejiang University Baima Lake Laboratory Zhejiang University

Molten salt is considered as a promising heat storage and heat transfer medium due to its efficient thermophysical *** order to study the compatibility of five new mixed molten salts obtained with KnO3,nanO3,K2CO3,Ca（nO3）2·4H2O,ZnCl2,naF,na2CO3,naCl and MgO as materials and 316L stainless steel,corrosion weight loss,scanning electron microscopy,elemental analysis and XRD were used to analyze the compatibility of 316L stainless steel in the new mixed molten salt at different time and *** corrosion behavior under the conditions was studied and *** compatibility data was obtained,and the corrosion mechanism of 316L stainless steel in mixed molten salts was *** results show that the corrosion weight of 316L stainless steel increases,and the corrosion degree of grain,crystal crack depth and oxidation degree increase gradually with the increase of temperature and *** corrosion of molten salt on alloy is mainly caused by the selective diffusion loss and corrosion of Cr,Fe and other elements,and is accompanied by the formation of different metal *** formation of metal oxides can slow down metal corrosion and loss to a certain *** corrosion results under different working conditions show that 316L stainless steel has good compatibility with the new mixed molten salt,and has certain application value in the field of heat transfer and energy storage.

关键词： 316L stainless steel corrosion resistance heat treatment molten salt

Spontaneous Infection and Periodic Evolving of Domain in a Diffusive SIS Epidemic Model

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 164-191页

作者： Qiang Wen Guo-qiang ren Bin Liu School of Mathematics and Statistics Huazhong University of Science and TechnologyWuhan430074China Hubei Key Laboratory of Engineering Modeling and Scientific Computing Huazhong University of Science and TechnologyWuhan430074China

In this paper, we consider a susceptible-infective-susceptible(SIS) reaction-diffusion epidemic model with spontaneous infection and logistic source in a periodically evolving domain. Using the iterative technique,the uniform boundedness of solution is established. In addition, the spatial-temporal risk index R0(ρ) depending on the domain evolution rate ρ(t) as well as its analytical properties are discussed. The monotonicity of R0(ρ)with respect to the diffusion coefficients of the infected dI, the spontaneous infection rate η(ρ(t)y) and interval length L is investigated under appropriate conditions. Further, the existence and asymptotic behavior of periodic endemic equilibria are explored by upper and lower solution method. Finally, some numerical simulations are presented to illustrate our analytical results. Our results provide valuable information for disease control and prevention.

关键词： diffusive SIS model spontaneous infection periodically evolving domain periodic endemic equilibrium

Empirical model of concrete block fragment behavior under explosion loads

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Science China(Technological Sciences) 2024年第8期67卷 2515-2529页

作者： YAnG Shuai nInG JianGuo ren HuiLan XU XiangZhao State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of TechnologyBeijing 100081China

Concrete structures undergo integral fragmentation under explosion loads. The fragmentation degree and particle-size distribution of concrete blocks under explosion loads must be considered during mining to ensure safety. In this study, the impulse is calculated based on the relationship between overpressure and time, and the impact energy of the explosion wave is obtained based on blast theory. Subsequently, the Mohr-Coulomb shear strength fracture criterion is introduced to determine the ultimate shear stress of the concrete materials, and an empirical model that can effectively calculate the energy consumption of concrete blocks under explosion loads is established. Furthermore, concrete fragments with different particle sizes under explosion scenarios are quantitatively predicted with the principle of energy conservation. Finally, explosion tests with different top standoff distances are conducted, and the concrete fragments after the explosion tests are recovered, sieved, weighed, and counted to obtain experimental data. The effectiveness of the fragment empirical model is verified by comparing the model calculation results with the experimental data. The proposed model can be used as a reference for civil blasting, protective engineering design, and explosion-damage assessment.

关键词： concrete structures explosion loads fragment behavior empirical model

Energy and exergy analyses and optimizations for two-stage TEC driven by two-stage TEG with Thomson effect

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Science China(Technological Sciences) 2024年第4期67卷 1077-1093页

作者： CHEn LinGen GE YanLin FEnG HuiJun ren TingTing Institute of Thermal Science and Power Engineering Wuhan Institute of TechnologyWuhan 430205China Hubei Provincial Engineering Technology Research Center of Green Chemical Equipment Wuhan 430205China School of Mechanical&Electrical Engineering Wuhan Institute of TechnologyWuhan 430205China

Based on the non-equilibrium thermodynamics and energy and exergy analyses,a thermodynamic model of two-stage thermoelectric(TE)cooler(TTEC)driven by two-stage TE generator(TTEG)(TTEG-TTEC)combined TE device is established with involving Thomson effect by fitting method of variable physical parameters of TE *** total number of TE elements as constraint,influences of number distributions of TE elements on three device performance indictors,that is,cooling load,maximum COP and maximum exergetic efficiency,are *** number distributions of TE elements are optimized with three maximum performance indictors as the objectives,*** of hot-junction temperature of TTEG and coldjunction temperature of TTEC on optimization results are analyzed,and difference between optimization results corresponding to three performance indicators are *** performance intervals and optimal variable intervals are *** of Thomson effect on three general performance indicators,three optimal performance indicators and optimal variables are comparatively *** effect reduces three general performance indicators and three optimal performance indicators of *** hot-and cold-junction temperatures of TTEG and TTEC are 450,305,325 and 295 K,respectively,Thomson effect reduced maximum cooling load,maximum COP and maximum exergetic efficiency from 9.528 W,9.043×10^(-2)and2.552%to 6.651 W,6.286×10^(-2)and 1.752%,respectively.

关键词： non-equilibrium thermodynamics cooling load COP exergetic efficiency combined thermoelectric device performance optimization