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研究目的:基于找形分析建立的细胞骨架力学模型研究微丝束对细胞骨架刚度的影响。创新要点:目前存在的细胞模型很少考虑微丝束对细胞力学特性的重要作用。本文基于细胞找形模型模拟了同时包含微丝和微丝束的细胞骨架网络结构,并且分析了细胞中微丝束的排列方向、微丝束的含量以及微丝波动对细胞刚度的影响。研究方法:基于找形模型,随机生成由微丝、微丝束(梁单元)以及交联蛋白(索单元)形成的细胞骨架网络结构,依靠非线性有限元计算和样本统计,计算出模型的弹性模量。通过分别改变模型中微丝束的排列方向、微丝束的含量以及模型初始最大位移等参数,得出细胞骨架模型的弹性模量随这些参数的变化趋势,以此来研究微丝束对细胞刚度的影响。重要结论:细胞骨架网络中微丝的波动会导致细胞刚度降低;与拉伸方向平行排列的微丝束可以显著地提高细胞的刚度,相比之下随机分布的微丝束对细胞刚度没有贡献;在微丝材料总量固定的情况下,细胞刚度随着平行排列微丝束含量的增加呈现出先升高后降低的趋势。 相似文献
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魏瑞演 《福建工程学院学报》2002,(2)
在高温 (火灾 )条件下钢结构材料力学性能试验研究的基础上 ,建立高温下钢材的屈服强度 ,极限强度、弹性模量和极限应变等力学性能随温度变化的力学模型 ,利用广义clough模型 ,对平面钢框架进行分析 ,建立高温 (火灾 )条件下框架梁、柱杆件的单元刚度方程。 相似文献
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基于线弹性力学理论,建立门式起重机力学模型;采用有限单元法对该模型进行数值求解,并提出以20节点空间单元作为网格划分的基本单元.运用CATIA软件进行其三维建模,在ANSYS Workbench软件中,对该三维立体模型进行数值模拟,分析了载荷因素对起重机桥架结构的影响.结果显示,设计的门式起重机结构参数满足强度和刚度要求. 相似文献
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输送机线性系统的假设是在胶带力学特性和弹性模量不变的情况下近似提出的. 这种假设会使大型输送机产生理论误差和不正确的动力学仿真结果. 本文分析了基于胶带悬垂度的非线性特性, 推导了等效弹性模量的表达式, 研究了胶带等效弹性模量和弹性模量之间的关系, 并发现两者的比值在0. 1～1. 0之间变化. 提出了输送机有限单元模型的非线性运动方程及其增量方程和数值解法. 通过对一输送机动态特性的仿真分析, 发现用线性和非线性2种模型, 它们动态参数(如带速, 胶带加速度, 张力以及重锤位移和张力波速)的计算误差介于6%～50% 之间. 相似文献
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目的：探讨SD大鼠阴茎海绵体平滑肌细胞体外培养方法的可行性.方法：分离并消化大鼠阴茎海绵体平滑肌细胞,采用胶原酶消化组织块方法,并进行免疫组化鉴定.结果：大鼠阴茎海绵体平滑肌细胞为梭形,呈长轴平行排列,易体外贴壁,经消化酶消化后,24h内贴壁的细胞α-平滑肌肌动蛋白（α-SMA）表达较其它时段贴壁的细胞高.结论：大鼠阴茎海绵体平滑肌细胞原代培养可行,对研究ED病治疗机制有重要意义. 相似文献
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本文采用三维杆系力学分析模型对钢结构框架进行分析,避免了传统的有限元方法要对构件大量划分网格进行计算而导致的计算自由度巨大,计算耗时的缺点。对于杆件单元,本文采用了一种变刚度的杆单元模型,建立了考虑塑性铰分布长度影响的构件单元刚度矩阵。在此基础上对经典的算例模型进行了静力全过程分析。 相似文献
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近年来认知心理学家不断尝试将平行分布处理模式应用于语篇分析,在认知模型理论基础上探讨平行分布处理模式能否模拟语篇认知模型,二者结合的好处之一在于可以将语篇理解过程的心理表征外显化,另外还可以确定信息网络结构中各个输入单元相互作用的运动路径。本文运用这种模拟研究,以《寂静的春天》为例,解读其语篇主题。 相似文献
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孙济洲 《天津大学学报(英文版)》2002,8(3):178-182
对利用网络资源解决复杂且耗时的计算问题做了尝试 .选择典型的粒子跟踪整体光照计算问题作为研究对象 ,提出一种改进的且充分发掘其内在相关特性的密度估计算法 .在以太网连接的多台微机上 ,以PVM (并行虚拟机 )机制实现了该算法的并行计算 .通过对各项运算性能指标的测试与分析 ,结果显示可获得良好的加速比 ,并且PVM在分布式网络并行计算上将有很好的应用前景 相似文献
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韩锦华 《西安文理学院学报》2014,(3):45-49
现实当中的许多复杂网络都无法避免地受到来自自然灾害或人为的攻击,从而导致网络破碎成很多大大小小的子集团.计算随机网络和BA无标度网络在随机删除节点与蓄意删除节点两种情况下产生的除最大连通图外其他子集团数量的情况.在产生的子集团中,结果发现它们特点是当节点删除比例f从0增大到1过程中,子集团的数量先增大后减小.包含节点数量较小的子集团数量占子集团总数量的大多数.子集团尺寸与相应数量在尺寸较小时近似成幂律关系.随机与蓄意删除节点时,随机网络与BA无标度网络产生子集团数量的最大值存在差异. 相似文献
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Actin can be found in all kinds ofeukaryotic cells, maintaining their shapes and motilities, while its dynamics in sperm cells is understood less than their nonmuscle somatic cell counterparts. Spermatogenesis is a complicated process, resulting in the production of mature sperm from primordial germ cell. Significant structural and biochemical changes take place in the seminiferous epithelium of the adult testis during spermatogenesis. It was proved that all mammalian sperm contain actin, and that F-actin may play an important role during spermatogenesis, especially in nuclear shaping. Recently a new model for sperm head elongation based on the acrosome-acroplaxome-manchette complex has been proposed. In Drosophila, F-actin assembly is supposed to be very crucial during individualization. In this mini-review, we provide an overview of the structure, function, and regulation characteristics of actin cytoskeleton, and a summary of the current status of research of actin-based structure and movement is also provided, with emphasis on the role of actins in sperm head shaping during spermiogenesis and the cell junction dynamics in the testis. Research of the Sertoli ectoplasmic specialization is in the spotlight, which is a testis-specific actin-based junction very important for the movement of germ cells across the epithelium. Study of the molecular architecture and the regulating mechanism of the Sertoli ectoplasmic specialization has become an intriguing field. All this may lead to a new strategy for male infertility and,at the same time, a novel idea may result in devising much safer contraception with high efficiency. It is hoped that the advances listed in this review would give developmental and morphological researchers a favorable investigating outline and could help to enlarge the view of new strategies and models for actin dynamics during spermatogenesis. 相似文献
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Actin can be found in all kinds of eukaryotic cells, maintaining their shapes and motilities, while its dynamics in sperm cells is understood less than their nonmuscle somatic cell counterparts. Spermatogenesis is a complicated process, resulting in the production of mature sperm from primordial germ cell. Significant structural and biochemical changes take place in the seminif-erous epithelium of the adult testis during spermatogenesis. It was proved that all mammalian sperm contain actin, and that F-actin may play an important role during spermatogenesis, especially in nuclear shaping. Recently a new model for sperm head elonga-tion based on the acrosome-acroplaxome-manchette complex has been proposed. In Drosophila, F-actin assembly is supposed to be very crucial during individualization. In this mini-review, we provide an overview of the structure, function, and regulation characteristics of actin cytoskeleton, and a summary of the current status of research of actin-based structure and movement is also provided, with emphasis on the role of actins in sperm head shaping during spermiogenesis and the cell junction dynamics in the testis. Research of the Sertoli ectoplasmic specialization is in the spotlight, which is a testis-specific actin-based junction very important for the movement of germ cells across the epithelium. Study of the molecular architecture and the regulating mechanism of the Sertoli ectoplasmic specialization has become an intriguing field. All this may lead to a new strategy for male infertility and, at the same time, a novel idea may result in devising much safer contraception with high efficiency. It is hoped that the advances listed in this review would give developmental and morphological researchers a favorable investigating outline and could help to enlarge the view of new strategies and models for actin dynamics during spermatogenesis. 相似文献
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采用一种神经网络算法——径向基函数来选择无线传感器网络的节点簇首,它具有并行处理能力、分布式存储以及快速学习等优点.通过分析得出与节点作为簇首相关的4个因素:节点的剩余能量,周围分布的节点的数目,中心度和距离基站的位置.把这4个因素作为神经网络的输入变量,输出变量就是该节点作为簇首的适应度值.根据网络规模的大小,基站选出一组作为簇首的节点,然后广播作为簇首的节点号的消息.如果一个节点被选为簇首,就向周围广播自己的身份并成立一个新簇,周围的非簇首节点要求加入该簇并成为它的成员.每簇中由簇首负责管理它的成员并执行数据融合等功能.实验结果表明,与其他算法相比,该算法能显著地延长传感器网络的生命. 相似文献
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Xiao-pei LU Da-wei YAO Yi CHEN Li-tian WANG An-ping DONG Liang MENG Jia-bin LIU 《浙江大学学报(A卷英文版)》2014,15(2):149-156
Cu-12% Fe （in weight） composite was prepared by casting, pretreating, and cold drawing. The microstructure was observed and Vickers hardness was measured for the composite at various drawing strains. Cu and Fe grains could evolve into aligned filaments during the drawing process. X-ray diffraction （XRD） was used to analyze the orientation evolution during the drawing process. The axial direction of the filamentary structure has different preferred orientations from the radial directions. The strain of Fe grains linearly increases with an increase in the drawing strain up to 6.0, and deviates from the linear relation when the drawing strain is higher than 6.0. With an increase in the drawing strain, the microstructure scales of Fe filaments exponentially decrease. The density of the interface between Cu and Fe phases exponentially increases with an increase in the aspect ratio of Fe filaments. There is a similar Hall-Perch relationship between the hardness and Fe filament spacing. The refined microstructure from drawing deformation at drawing strains lower than 3.0 can induce a more significant hardening effect than that at drawing strains higher than 3.0. 相似文献
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Application of honey-bee mating optimization on state estimation of a power distribution system including distributed generators 总被引：1，自引：0，他引：1
Taher Niknam 《浙江大学学报(A卷英文版)》2008,9(12):1753-1764
We present a new approach based on honey-bee mating optimization to estimate the state variables in distribution networks including distributed generators. The proposed method considers practical models of electrical equipments such as static var compensators, voltage regulators, and under-load tap changer transformers, which have usually nonlinear and discrete characteristics. The feasibility of the proposed approach is demonstrated by comparison with the methods based on neural networks, ant colony optimization, and genetic algorithms for two test systems, a network with 34-bus radial test feeders and a realistic 80-bus 20 kV network. 相似文献
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陈东 《武汉职业技术学院学报》2005,4(5):85-88
提出将分布式网络系统中的嵌入式单元设计成含双单片机并行通信的主从式结构的设想，认为将嵌入式单元与Internet结合，形成具有远程访问能力的分布式网络系统，最大限度的实现了嵌入式系统“轻、薄、短小、多功能、低成本”的发展目标，因而特别适用于低端嵌入式现场应用。 相似文献
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Swarm intelligence inspired by the social behavior of ants boasts a number of attractive features,including adaptation,robustness and distributed,decentralized nature,which are well suited for routing in modern communication networks.This paper describes an adaptive swarm-based routing algorithm that increases convergence speed,reduces routing instabilities and oscillations by using a novel variation of reinforcement learning and a technique called momentum.Experiment on the dynamic network showed that adaptive swarm-based routing learns the optimum routing in terms of convergence speed and average packet latency. 相似文献