高温超导电缆研究进展综述

人们对电能需求的持续增长,促使电网输电密度和输电容量逐渐增大,传统的输电技术将遇到越来越多的问题。高温超导电缆具有传输容量大和功率密度高等优势,是解决这些问题和满足未来大容量电力传输的重要技术之一。在综合分析国内外大量文献资料的基础上,介绍高温超导电缆的基本结构、发展现状和关键技术,总结制约其工业化应用过程当中面对的主要问题,并提出了高温超导电缆的发展建议。     

一种基于双目视觉技术的运动线缆空间位姿测量方法

为了测量柔性运动线缆的空间位姿,提出了一种基于双目视觉的中心线匹配法,可以对长径比较大的柔性线缆类零件的空间位姿进行光学测量。通过运动估计方法提取ROI(感兴趣区域),对ROI进行二值化处理,再通过细化算法提取区域的骨架作为中心线,结合极线约束寻找中心线上的匹配点对,重建中心线上点列并拟合空间中心线。建立了实验系统,通过实验测试表明,该方法平均测量误差为0.09mm,证明了实验方法的正确性和可行性。     

面向工业环境开发的数据通信电缆的研究与设计

在工业生产中对稳定可靠的实时自动化控制的需求日益增高的情况下,工业以太网作为解决方案迅速成为关注的焦点.工业环境有其特殊性,因此相应的工业以太网线的设计也必须要考虑到对极限温度、湿度、震动等的特殊要求.这种要求往往很大程度地超出了一般用于带有中央空调的办公环境中普通网线的应用范围.因此工业网线的种种设计都值得研究探讨.介绍了工业网线设计的基本概念并对工业网线设计的特殊考虑进行了探讨.     

维生素D缺乏诱导小儿呆小病与血液微量元素的关系研究

目的探讨维生素D缺乏诱导呆小病新生儿血液中微量元素含量的变化。方法采用微分电位溶出法测定维生素D缺乏诱导呆小病的新生儿与健康新生儿血液中微量元素的含量。结果呆小病组血清锌、镁、铁、钙均低于正常,全血铅、血清铜均高于正常。结论小儿维生素D缺乏诱导呆小病新生儿血液微量元素存在一定的失衡,与感染所造成的机体伤害有一定的关系,因此需要及时补充和调理微量元素,对疾病的治疗和恢复有重要意义。     

Determining distributed parameters in a neuronal cable model on a tree graph

For graph domains without cycles, we show how unknown coefficients and source terms for a parabolic equation can be recovered from the dynamical Neumann‐to‐Dirichlet map associated with the boundary vertices. Through use of a companion wave equation problem, the topology of the tree graph, degree of the vertices, and edge lengths can also be recovered. The motivation for this work comes from a neuronal cable equation defined on the neuron's dendritic tree, and the inverse problem concerns parameter identification of k unknown distributed conductance parameters. Copyright © 2017 John Wiley & Sons, Ltd.     

大柔性Stewart平台的刚度研究

大型射电望远镜舱索系统通过六根索长的协调变化驱动馈源舱作跟踪射电源的六自由度运动,其工作特点类似于Stewart平台,因此被看作大柔性Stewart平台。基于大型射电望远镜舱索系统50m缩比模型,首先分析了悬索的垂跨比与悬索张力、系统基频之间的关系;其次,研究了大柔性Stewart平台零位时的竖向刚度;最后,对舱体在不同位姿处的扭转刚度进行分析。研究工作为变结构悬索系统的振动分析与运动控制奠定了基础。     

Large Amplitude Three-Dimensional Free Vibrations of Inclined Sagged Elastic Cables

The nonlinear characteristics in the large amplitude three-dimensionalfree vibrations of inclined sagged elastic cables are investigated. Amodel formulation which is not limited to cables having smallsag-to-span ratios and takes into account the axial deformation effectis considered. Based on a multi-degree-of-freedom cable model, a finitedifference discretization is employed within a numerical solution of thegoverning equations of three-dimensional coupled motion. Variousnumerical examples of arbitrarily inclined sagged cables with initialout-of-plane or in-plane motions are carried out for the case of aspecified end tension. The major findings consist of highlighting theextent of two-and three-dimensional nonlinear couplings, the occurrenceof nonlinear dynamic tensions, and the meaningfulness of modaltransition phenomena ensuing from the activation of various internalresonance conditions. The influence of cable inclination on thenonlinear dynamic behavior is also evaluated. Comprehensive discussionand comparison of large amplitude free vibrations of horizontal andinclined sagged cables are presented.     

Numerical simulations of chaotic dynamics in a model of an elastic cable

The finite motions of a suspended elastic cable subjected to a planar harmonic excitation can be studied accurately enough through a single ordinary-differential equation with quadratic and cubic nonlinearities.The possible onset of chaotic motion for the cable in the region between the one-half subharmonic resonance condition and the primary one is analysed via numerical simulations. Chaotic charts in the parameter space of the excitation are obtained and the transition from periodic to chaotic regimes is analysed in detail by using phase-plane portraits, Poincaré maps, frequency-power spectra, Lyapunov exponents and fractal dimensions as chaotic measures. Period-doubling, sudden changes and intermittency bifurcations are observed.Part of this work was presented at the XVIIth Int. Congr. of Theor. and Appl. Mech., Grenoble, August 1988.     

STATIC ANALYSIS OF CABLE STRUCTURE

Based on the nonlinear geometric relation between strain and displacement for flexible cable, the equilibrium equation under self-weight and influence of temperature was established and an analytical solution of displacement and tension distribution defined in Eulerian coordinate system was accurately obtained. The nonlinear algebraic equations caused by cable structure were solved directly using the modified Powell hybrid algorithm with high precision routine DNEQNE of Fortran. For example, a cable structure consisting of three cables jointly supported by a vertical spring and all the other ends fixed was calculated and compared with various methods by other scholars.     

非线性梁索单元理论在轻型桅杆设计中的应用

导出了轻型桅杆设计计算的非线性梁与索单元理论和方法，求出的桅杆截面内力考虑了索单元的非线性影响，计入了桅杆杆身在轴压下弯曲失稳的效应。在计算桅杆时采用了增量Ｎｅｗｔｏｎ－Ｒａｐｈｓｏｎ迭代法，如果在设计荷载作用下的迭代过程收敛，则桅杆不会发生绕两个主轴的整体弯曲失稳。本文方法解决了轻型桅杆设计中的强度、整体和层间稳定及刚度计算的难题。