检索结果-南通市图书馆

第十三届全国体育科学大会

作者：高立栋叶靖怡 kovács bálint Zsolt Radak Zhuqing Mao 顾耀东

研究目的:弓步是下肢肌肉力量训练和康复计划的一个重要部分。这项训练通常是为了加强下肢肌肉产生更高的力量的能力,特别是股四头肌,并尽量减少关节损伤的风险,以及发展功能性姿势平衡。与更常用的深蹲相比,弓步具有更多的平衡,因此它... 详细信息

研究目的:弓步是下肢肌肉力量训练和康复计划的一个重要部分。这项训练通常是为了加强下肢肌肉产生更高的力量的能力,特别是股四头肌,并尽量减少关节损伤的风险,以及发展功能性姿势平衡。与更常用的深蹲相比,弓步具有更多的平衡,因此它可以更安全地用于加强股四头肌和腘绳肌,这对于步态和日常生活活动的适当康复是必要的。在比赛和训练时涉及到弓步的运动可能贯穿整个运动过程。而肌肉疲劳的特点是长时间暴露在活动中后肌肉效率和产力能力下降,已多次被证明对运动表现有负面影响。疲劳是运动中一个主要的伤害危险因素,但疲劳前后弓步变化的研究却较为稀少。目前缺乏关注疲劳是如何诱发前弓步中运动学和动力学的变化的研究。尽管在不同方向上的弓步和疲劳后的下肢闭合链练习的运动学表现相关研究较为丰富,但缺乏关于疲劳前后相关肌肉群在弓步中的运动学、动力学和力量产生的变化的信息。本研究的目的是研究在完成疲劳方案之前和之后,疲劳对前弓步期间下肢生物力学的影响。疲劳是造成损伤风险的一个主要因素,通过我们的客观数据来理解疲劳具体影响到下肢的哪些方面,并根据以往的研究了解疲劳带来的损伤机制和预防相应的损伤,了解损伤的原因并提供所需的认识,并有助于改善损伤预防方案。研究方法:15名健康年轻男性参与本实验,在进行疲劳协议之前和之后,我们测试了向前弓步,以获得疲劳期间的运动学和动力学变化,并观察髋关节、膝关节和踝关节以及相应肌肉的力量变化。使用borg Scale RPE 6-20量表,该量表与心率检测器一起使用以记录在疲劳方案过程中的主观疲劳和心率(HR)变化。一组疲劳协议包括在固定跑步机上以自选速度进行跑步400m和20次重复向前弓步(优势腿与非优势腿交替向前弓步然后回到起始位置),此疲劳方案皆在模仿在运动或娱乐环境中可能经历的下肢运动模式。一组疲劳协议完成后若未疲劳则进入下一组协议,如此重复进行。疲劳是通过HR和RPE的值来确定的。除参与者自身无法继续进行外,还包括参与者的心率超过为其年龄计算的最大心率的90%和borg量表评分超过RPE> 17(非常困难)。使用八相机Vicon运动捕捉系统来捕捉运动轨迹。嵌入式Kistler三维测力板用于同步记录地面反作用力。本实验运用的该模型是基于原始OpenSim模型进行了调整,并更新了膝关节冠状面和水平面的额外运动范围。使用OpenSim软件来进行IK(逆运动学)、ID(逆动力学)和SO(静态优化)的处理。通过Delsys EMG测试系统同步采集股直肌、股二头肌长肌、胫骨前肌、腓肠肌的EMG信号与OpenSim静态优化算法输出的肌肉激活程度进行比较,对该模型进行了验证。在这之前使用CON-TRE-MJ等速肌力测试系统采集它们的最大自主收缩。本研究采用SPSS 26用来分析髋、膝和踝关节在矢状面和髋关节和膝关节在水平面的ROM,峰值角度,峰值力矩和疲劳前后下的峰值vGRF和两个峰值A和b,分别用配对样本T检验来分析是否具有显著性。分析前对数据先进行了Shapiro-Wilk正态性检验。研究结果:疲劳协议后,在髋关节的矢状面和水平面中,两者的峰值角度和关节活动范围(ROM)都有所增加,同时矢状面峰值力矩显著增大,躯干和骨盆运动幅度增大。膝关节矢状面的峰值角度和ROM也有所增加,同时在水平面上均有变化,然而在矢状面力矩减小,水平面有所增加。对踝关节来说,虽然ROM并没有明显变化,但峰值角度却明显降低,力矩显著下降。踝关节有更多的跖屈趋势。对于疲劳前后的vGRF,仅在初始接触峰值(A)减小。平均峰值和蹬离期峰值(b)并没有统计学意义,但平均峰值却略有增加而蹬离期峰值在减小,疲劳后踝关节的更多跖屈使得相应的反作用力减小。疲劳前后,股二头肌与腓肠肌的平均肌力和最大肌力均减小。股四头肌与胫骨前肌的平均肌力和最大肌力均增大。在这些肌肉中,股四头肌的平均肌力和最大肌力增加的最明显。研究结论:我们认为前弓步易受到疲劳的影响。即在疲劳后,髋关节和膝关节在矢状面有向前倾斜的趋势,以及在水平面的偏移增加,此外,踝关节的跖屈肌肉活动量增加,身体姿势表现不稳定,这表明膝关节、脚和踝关节可能有潜在的受伤风险。此外,股四头肌在疲劳后受到的影响最大。为了避免疲劳后不稳定造成的伤害,训练者应更注重髋关节和膝关节肌肉的力量训练和协调训练,以更有意识地控制躯干的稳定性。

关键词：前弓步运动学动力学疲劳

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Transient transport processes in deformable porous media

引用

Chinese Physics b 2011年第11期20卷 167-175页

作者： cs.Mészáros A.bálint Szent István University Department of Physics and Process Control Szent István University Department of Chemistry and Biochemistry

The basic partial differential equations relevant for convection-diffusion and convection-diffusion-wave phenomena arc presented and solved analytically by using the MAPLE symbolic computer algebra system. The possible general nonlinear character of the constitutive equation of the convection-discussion process is replaced by a direct posteriori stochastic refinement of its solution represented for Dirichlet-type boundary conditions. A thermodynamic analysis is performed for connecting the relaxation time constants and Jacobi-determinants of deformations at transient transport processes. Finally, a new procedure for general description of coupled transport processes on the basis of the formalism originally developed for convection-free phenomena is presented by matrix analysis methods in the Fourier space.

关键词： convection binary mixtures relaxation time matrix polynomials

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation Part III: Influence on the Torque-speed Characteristic

引用

CES Transactions on Electrical Machines and Systems 2024年第1期8卷 86-102页

作者： G.kovács the Ganz Electric Works BudapestHungary

The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the ***, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.

关键词： Asynchronous parasitic torques Induction motor Squirrel cage rotor Space harmonics Synchronous parasitic torques

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation-Part Ⅰ: Differential Leakage, Attenuation, Asynchronous Parasitic Torques

引用

CES Transactions on Electrical Machines and Systems 2023年第4期7卷 320-329页

作者： G.kovács Ganz Electric Works 1095 BudapestHungary

The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.

关键词： Asynchronous parasitic torque Attenuation Differential leakage Squirrel cage induction motor Winding harmonics

来源：

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Tie-line Power Flow Control Method for Gridconnected Microgrids with SMES based on Optimization and Fuzzy Logic

引用

Journal of Modern Power Systems and Clean Energy 2020年第5期8卷 941-950页

作者： Sayed M.Said Abdelfatah Ali bálint Hartmann Department of Electrical Engineering Aswan University81542 AswanEgypt Department of Electric Power Engineering Budapest University of Technology and Economics1111 BudapestHungary Department of Electrical Engineering South Valley University83523 QenaEgypt

In an active distribution grid,renewable energy sources(RESs)such as photovoltaic(PV)and energy storage systems(e.g.,superconducting magnetic energy storage(SMES))can be combined with consumers to compose a microgrid(MG).The high penetration of PV causes high fluctuations of tie-line power flow and highly affects power system *** can lead to several technical problems such as voltage fluctuations and excessive power *** this paper,a fuzzy logic control based SMES method(FSM)and an optimized fuzzy logic control based SMES method(OFSM)are proposed for minimizing the tie-line power ***,the fluctuations and transmission power losses are *** FSM,SMES is used with a robust fuzzy logic controller(FLC)for controlling the tie-line power *** optimization model is employed in OFSM to simultaneously optimize the input parameters of the FLC and the reactive power of the voltage source converter(VSC)of *** objective function of minimizing the tieline power flow is incorporated into the optimization *** swarm optimization(PSO)algorithm is utilized to solve the optimization problem while the constraints of the utility power grid,VSC,and SMES are *** simulation results demonstrate the effectiveness and robustness of the proposed methods.

关键词： Utility power grid microgrid photovoltaic(PV) superconducting magnetic energy storage(SMES) tie-line power fuzzy logic control(FLC)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

On Non-normal Arc-Transitive 4-Valent Dihedrants

引用

Acta Mathematica Sinica,English Series 2010年第8期26卷 1485-1498页

作者： István kovcs botjan KUZMAN Aleksander MALNI FAMNIT University of Primorska PeF University of Ljubljana IMFM University of Ljubljana

Let X be a connected non-normal 4-valent arc-transitive Cayley graph on a dihedral group Dn such that X is bipartite, with the two bipartition sets being the two orbits of the cyclic subgroup within Dn. It is shown that X is isomorphic either to the lexicographic product Cn[2K1] with n 〉 4 even, or to one of the five sporadic graphs on 10, 14, 26, 28 and 30 vertices, respectively.

关键词： Cayley graph arc transitivity dihedral group

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Complications in children with percutaneous endoscopic gastrostomy (PEG) placement

引用

World Journal of Pediatrics 2019年第1期15卷 12-16页

作者： brigitta balogh Tamás kovács Amulya Kumar Saxena Division of Pediatric Surgery Department of PediatricsUniversity of SzegedKorányi fasor 14-15Szeged 6725Hungary Department of Pediatric Surgery Chelsea Children's HospitalChelsea and Westminster NHS Fdn TrustImperial College LondonLondonUK

Introduction The aim of this study was to analyze the complication rates and mortality in association with different operative techniques of percutaneous endoscopic gastrostomy (PEG),age,underlying diseases and other risk ***,analysis of the indications of PEG insertion and the underlying comorbidities was also *** This study performs a literature analysis of PEG-related complications in *** was searched on PubMed(R) (1994-2017) using terms 'percutaneous endoscopic gastrostomy','complications','mortality' and 'children'.Results Eighteen articles with 4631 patients were *** mean age was 3 years (0-26 years).Operative techniques were:pull technique in 3507 (75.7%),1 stage PEG insertion in 449 (9.7%),introducer technique in 435 (9.4%),image-guided technique in 195 (4.2%) and laparoscopic-assisted PEG in 45 (1.6%).Most frequent indications for PEG insertion were dysphagia (n =859,32.6%),failure to thrive (n =723,27.5%) and feeding difficulties (n =459,17.4%).Minor complications developed in n 1518 patients (33%),including granulation (n =478,10.3%),local infection (n =384,8.3%) and leakage (n =279,6%).In 464 (10%) patients,major complications occurred;the most common were systemic infection (n =163,3.5%)and cellulitis (n =47,1%).Severe complication like perforation occurred in less than 0.3%.Patients with lethal outcomes (n =7,0.15%) had severe comorbidities;and the cause of mortality was sepsis in all *** or young age did not affect complication *** with ventriculoperitoneal (VP) shunt had higher risk of major *** high-risk patients,laparoscopic-assisted PEG insertion had less major and severe complication than traditional pull *** PEG is a safe operative technique;although minor complications are relatively common and occur in up to 1/3 of patients,there is a fairly low rate of severe ***-thirds of PEG patients have at least one ***

关键词： Children Complications Percutaneous endoscopic gastrostomy

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Isomorphisms of Cubic Cayley Graphs on Dihedral Groups and Sparse Circulant Matrices

引用

Acta Mathematica Sinica,English Series 2023年第4期39卷 618-632页

作者： Istvan kovAcs UP IAM&FAMNIT University of PrimorskaMuzejski trg 26000 KoperSlovenia

We show that,up to isomorphism,there is a unique non-CI connected cubic Cayley graph on the dihedral group of order 2n for each even number n≥*** answers in the negative the question of Li whether all connected cubic Cayley graphs are CI-graphs(Discrete Math.,256,301-334(2002)).As an application,a formula is derived for the number of isomorphism classes of connected cubic Cayley graphs on dihedral groups,which generalises the earlier formula of Huang et *** with the particular case when n is a prime(Acta ***.,***.,33,996-1011(2017)).As another application,a short proof is also given for a result on sparse circulant matrices obtained by Wiedemann and Zieve(arXiv preprint,(2007)).

关键词： Cayley graph graph isomorphism dihedral group circulant matrix

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Hyperactive learning for data-driven interatomic potentials

引用

npj Computational Materials 2023年第1期9卷 599-612页

作者： Cas van der Oord Matthias Sachs Dávid Péter kovács Christoph Ortner Gábor csányi University of Cambridge Cambridge CB21PZUK University of birmingham Birmingham B152TTUK University of british Columbia VancouverBC V6T 1Z2Canada

Data-driven interatomic potentials have emerged as a powerful tool for approximating ab initio potential energy *** most time-consuming step in creating these interatomic potentials is typically the generation of a suitable training *** aid this process hyperactive learning(HAL),an accelerated active learning scheme,is presented as a method for rapid automated training database *** adds a biasing term to a physically motivated sampler(*** dynamics)driving atomic structures towards uncertainty in turn generating unseen or valuable training *** proposed HAL framework is used to develop atomic cluster expansion(ACE)interatomic potentials for the AlSi10 alloy and polyethylene glycol(PEG)polymer starting from roughly a dozen initial *** HAL generated ACE potentials are shown to be able to determine macroscopic properties,such as melting temperature and density,with close to experimental accuracy.

关键词： starting generating consuming

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

On the neutrality of two symmetric TSP solvers toward instance specification

引用

Science China(Information Sciences) 2019年第11期62卷 198-200页

作者： Gloria Cerasela CRI?AN László barna IANTOVIcs László kovács Faculty of Sciences Vasile Alecsandri University Faculty of Sciences and Letters University of MedicinePharmacy Sciences and Technology Faculty of Mechanical Engineering and Informatics University of Miskolc

Dear editor,Currently, many computationally difficult problems can be solved using very efficient *** of these state-of-the-art methods have online implementations. The research question addressed herein is how sensit... 详细信息

关键词： On the neutrality of two symmetric TSP solvers toward instance specification

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：