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拇外翻足三维有限元模型构建及其第1、2跖列生物力学分析

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医用生物力学 2024年第2期39卷 272-277页

作者：耿艳利苑智文宣伯凯徐敏河北工业大学人工智能与数据科学学院天津300401 智能康复装置与检测技术教育部工程研究中心天津300401 天津医科大学朱宪彝纪念医院天津300134

目的建立拇外翻足有限元模型,研究不同拉力下第1、2跖列的应力及位移变化情况。方法将采集的拇外翻病人足部CT图像导入Mimics软件,重建足部三维骨骼模型;利用3-matic软件对重建模型进行网格划分与体网格生成;将优化处理过的模型导入ANSY... 详细信息

目的建立拇外翻足有限元模型,研究不同拉力下第1、2跖列的应力及位移变化情况。方法将采集的拇外翻病人足部CT图像导入Mimics软件,重建足部三维骨骼模型;利用3-matic软件对重建模型进行网格划分与体网格生成;将优化处理过的模型导入ANSYS中进行有限元分析,通过改变拉力大小、方向验证拉力与第1、2跖列的应力、位移之间的关系。结果对第1近节趾骨施加不同大小、方向的拉力,当力小于12 N时,随着拉力的增加,第1趾骨位移变化较为明显,拉力每增大2 N,位移约增加1 mm;当力大于12 N时,随着拉力的增加,第1趾骨应力不断增加,而位移只发生微小变化;而当力保持12 N不变,以15°间隔改变力的方向时,第1、2跖列的应力大小及其分布随方向的变化而改变,同时位移也会产生相应的变化,且当力的方向与第2趾骨方向越趋于垂直时,第1趾骨产生的位移越大。结论有限元分析技术可以形象、准确地分析第1、2跖列在不同拉力下的应力及位移变化情况,为拇外翻矫形器的设计奠定基础。

关键词：拇外翻拉力应力位移矫形器

The Active Above-Knee Prosthesis Gait Control Based on the EMPC

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The Active Above-Knee Prosthesis Gait Control Based on the E...

2015年中国智能自动化学术会议

作者： Yan Zhang Yongchang Zhang Lingling Chen bokai xuan School of Control Science and Engineering Hebei University of Technology

On-line optimization control has been recognized as a superior algorithm for constrained systems. To deal with various disturbances and serious nonlinearity,active above-knee prosthesis(AKP) is treated as constrained switching system in this paper. The kinetic characters of AKP were analyzed when an amputee was walking on level-ground. A piecewise affine model can be built, and the AKP system was divided into 15 subsystems. Explicit model predictive control algorithm was applied to switch between subsystems. State-space partitions and explicit control laws are calculated off-line. On-line control signal can be obtained by looking up table. This algorithm can make the prosthesis to track the flexion curve of health limb accurately. Finally, results are shown that this method can tune the control impedance for powered knee prostheses with less energy consumption and high operation speed.

关键词： Active above-knee prosthesis Piecewise affine model Explicit model predictive control Prosthesis control

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膝上型假肢的运动意图识别与控制

东南大学学报（自然科学版） 2017年第6期47卷 1107-1116页

作者：宣伯凯刘作军陈玲玲杨鹏河北工业大学控制科学与工程学院天津300130 河北工业大学智能康复装置与检测技术教育部工程研究中心天津300130

根据不同路况条件和典型步速的笛卡尔积组合,利用装配在残肢侧的陀螺仪、加速度计和足底前后的压力传感器的信息,通过相关性系数分析、传感器融合、隐马尔可夫模型的方法,判断假肢使用者的运动意图.以健肢运动状态为参考值,利用迭代学... 详细信息

根据不同路况条件和典型步速的笛卡尔积组合,利用装配在残肢侧的陀螺仪、加速度计和足底前后的压力传感器的信息,通过相关性系数分析、传感器融合、隐马尔可夫模型的方法,判断假肢使用者的运动意图.以健肢运动状态为参考值,利用迭代学习控制分别建立不同路况和步速情况下的控制知识数据库.通过传感器的关键状态变化信号驱动有限状态机状态转换,输出控制知识库中的控制量,实现假肢膝关节在不同路况、步速条件下对步态相位的控制.针对控制过程中出现的输出量实时偏差,采取了在线校正措施.对于有限状态机输出控制数据序列在时间同步上的超前和滞后问题,采取了相应的保持和补偿措施.结果表明,经隐马尔可夫模型处理后路况判断准确率可提升到91.7%,基于数据驱动的无模型控制方法能够实现对不同路况、步速下假肢步态的有效控制.

关键词：假肢运动意图迭代学习控制有限状态机

Time-Aware LSTM Neural Networks for Dynamic Personalized Recommendation on Business Intelligence

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Tsinghua Science and Technology 2024年第1期29卷 185-196页

作者： xuan Yang James A.Esquivel Graduate School Angeles University FoundationAngeles City 2009Philippines Shandong Provincial University Laboratory for Protected Horticulture Weifang University of Science and TechnologyWeifang 262700China

Personalized recommendation plays a critical role in providing decision-making support for product and service analysis in the field of business ***,deep neural network-based sequential recommendation models gained considerable ***,existing approaches pay litle attention to users'dynamically evolving interests,which are influenced by product attributes,especially product *** overcome these challenges,we propose a dynamic personalized recommendation model:***,we first embed product information and attribute information into a unified data ***,we exploit long short-term memory(LsTM)networks to characterize sequential behavior over multiple time periods and seize evolving interests by hierarchical LSTM ***,similarity values between users are measured through pairwise interest features,and personalized recommendation lists are generated.A series of experiments reveal the superiority of the proposed method compared withotheradvanced methods.

关键词： personalized recommendations evolving interests embedding LsTM networks

LSTM Network-Based Adaptation Approach for Dynamic Integration in Intelligent End-Edge-Cloud Systems

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Tsinghua Science and Technology 2024年第4期29卷 1219-1231页

作者： xuan Yang James A.Esquivel Graduate School Angeles University FoundationAngeles City 2009Philippinesand also with Shandong Provincial University Laboratory for Protected HorticultureWeifang University of Science and TechnologyWeifang 262700China Graduate School Angeles University FoundationAngeles City 2009Philippines

Edge computing, which migrates compute-intensive tasks to run on the storage resources of edge devices, efficiently reduces data transmission loss and protects data privacy. However, due to limited computing resources and storage capacity, edge devices fail to support real-time streaming data query and processing. To address this challenge, first, we propose a Long Short-Term Memory (LSTM) network-based adaptive approach in the intelligent end-edge-cloud system. Specifically, we maximize the Quality of Experience (QoE) of users by automatically adapting their resource requirements to the storage capacity of edge devices through an event mechanism. Second, to reduce the uncertainty and non-complete adaption of the edge device towards the user’s requirements, we use the LSTM network to analyze the storage capacity of the edge device in real time. Finally, the storage features of the edge devices are aggregated to the cloud to re-evaluate the comprehensive capability of the edge devices and ensure the fast response of the user devices during the dynamic adaptation matching process. A series of experimental results show that the proposed approach has superior performance compared with traditional centralized and matrix decomposition based approaches.

关键词： quality of experience data query end-edge-cloud Long Short-Term Memory(LSTM)networks

Synthesis and characterization of three new solid polyoxometalates based on Wells-Dawson-derived sandwich-type polyanions [Co_(4)(H_(2)O)_(2)(P_(2)W_(15)O_(56))_(2)]^(16-)

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第3期25卷 268-274页

作者： Jjijie YE xuan XU Chuande WU Department of Chemistry Zhejiang UniversityHangzhou 310058China

Three polyoxometalate-based hybrid coordination materials,[Co_(8)(H_(2)O)_(34)(pz)_(2){Co_(4)(H_(2)O)_(2)P_(4)W_(30)O_(112)}]·16H_(2)O(compound 1),[H_(3)O]_(4)[Co_(6)(H_(2)O)_(22)(pz)_(2){Co_(4)(H_(2)O)_(2)P_(4)W_(30)O_(112)}]·21H_(2)(compound 2),and[H_(3)O]_(4)[Co_(6)(H_(2)O)_(22){Co_(4)(H_(2)O)_(2)P_(4)W_(30)O_(112)}]·29H_(2)O(compound 3)(pz-pyrazine),were built from the linkage of[Co_(4)(H_(2)O)_(2)(P_(2)W_(15)O_(56)_(2)]^(16-)-(abbreviated as{Co_(4)P_(4)W_(30})polyanions and pz and/or cobalt(II)*** compounds 1 and 2 consisted of the same components,their lamellar networks were quite *** inorganic lamellar network in compound 3 was constructed by connecting{Co_(4)P_(4)W_(30)}units with cobalt(I)*** work demonstrates that the coordination modes of{Co_(4)P_(4)W_(30)}are very sensitive to synthesis conditions,while the ring-belt tetrametals are easily substituted by different transition metal cations under mild reaction conditions.

关键词： Cobalt Crystal structure Cyclic voltammetry Hybrid Polyoxometalate

Modified constitutive models for Inconel 718 considering current density and temperature in electrically assisted forming process

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Chinese Journal of Aeronautics 2024年第2期37卷 524-540页

作者： xuan CUI Rui ZHAO Min WAN School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Jiangxi 330000China

Electrically Assisted Forming(EAF)technology has obvious advantages in material *** develop an effective constitutive model considering electrical effects,room temperature and electrically assisted quasi-static uniaxial tensile tests were conducted using ultrathin nickelbased superalloy plates with a thickness of 0.25 *** research focused on the two most widely recognized effects:the Joule thermal and the electric athermal *** mechanism of current action can be divided into two scenarios:one considering the Joule thermal effect only,and the other considering both effects *** basic constitutive models,namely the Modified-Hollomon model and the Johnson-Cook(J-C)model,were selected to be optimized through the classification of two different situations,and four optimized constitutive models were *** was found that the J-C model with simultaneous consideration of the Joule thermal effect and electric athermal effect had the best prediction effect by comparing the results of these four ***,the accuracy of the optimization model was verified by finite element simulation of the electrically assisted stretching optimization *** results show that the constitutive model can effectively predict the temperature effect caused by the Joule heat effect and the athermal effect of current on the material.

关键词： Joule heating Elastoplasticity Plastic deformation Superalloys Constitutive models

A Review on Vibration Control of Multiple Cylinders Subjected to FlowInduced Vibrations

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China Ocean Engineering 2024年第2期38卷 183-197页

作者： XU Wan-hai MA Ye-xuan State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300350China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China

The fatigue damage caused by flow-induced vibration(FIV)is one of the major concerns for multiple cylindrical structures in many engineering *** FIV suppression is of great importance for the security of many cylindrical *** active and passive control methods have been employed for the vibration suppression of an isolated cylinder undergoing vortex-induced vibrations(VIV).The FIV suppression methods are mainly extended to the multiple cylinders from the vibration control of the isolated *** to the mutual interference between the multiple cylinders,the FIV mechanism is more complex than the VIV mechanism,which makes a great challenge for the FIV *** efforts have been devoted to vibration suppression of multiple cylinder systems undergoing FIV over the past two *** control methods,such as helical strakes,splitter plates,control rods and flexible sheets,are not always effective,depending on many influence factors,such as the spacing ratio,the arrangement geometrical shape,the flow velocity and the parameters of the vibration control *** FIV response,hydrodynamic features and wake patterns of the multiple cylinders equipped with vibration control devices are reviewed and *** FIV suppression efficiency of the vibration control methods are analyzed and compared considering different influence *** research on the FIV suppression of multiple cylinders is suggested to provide insight for the development of FIV control methods and promote engineering applications of FIV control methods.

关键词： flow-induced vibration vibration control multiple cylinders tandem side-by-side staggered

Recent progress in carbene-catalyzed fluoroalkylation

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Science China Chemistry 2024年第8期67卷 2448-2460页

作者： Bei Zhang xuan Zhang Jian Wang Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science and TechnologyNanjing 210044China School of Pharmaceutical Sciences Tsinghua UniversityBeijing 100084China

The fluoroalkyl fragment plays a vital role in various fields such as pharmaceuticals and materials science, and has a significant impact on human life not only on the present but also in the future. The insertion of fluoroalkyl groups into the chemical skeletons can cause considerable alternations in the chemical, physical and biological properties of molecules, which has attracted numerous scientists from different fields. This review focuses on N-heterocyclic carbene(NHC)-catalyzed fluoroalkylation reactions, providing a detailed analysis and summary of the achievements in the past two decades. Many successful examples clearly indicate that NHCs can catalyze the tranformation of fluoroalkylation reagents with various electronic characteristics, whether electrophilic, nucleophilic, or radical precursors. Herein, the fluoroalkylation reactions are classified based on different catalytic modes of NHCs: Lewis base catalysis, Umploung catalysis, radical catalysis and others. Meanwhile, by refining and systematically studying the contribution of NHC catalysis in fluoroalkylation reactions, this review is expected to provide valuable insights and enlightenment for related fields.

关键词： N-heterocyclic carbene fluoroalkylation radical catalysis