Comparison of the Activation Energies as Determined by DSC and by Conventional Methods

The results of determination of activation energies (E_A) of polymeric cable insulations obtained by conventional methods (usually based on the evaluation of changes of mechanical properties of insulations after their ageing in thermal chamber at different temperatures) have been compared with results obtained by methods employing the differential scanning calorimetry (DSC). Three DSC methods have been tested: the method according the ASTM E 698; measuring of DSC characteristics in the isothermal mode at several different temperatures; and the method based on evaluation of DSC characteristics of insulations after their thermal ageing in thermal chamber. The last method — which can be called as a modified conventional method, because instead of mechanical properties, the DSC characteristics are determined — has been found as most acceptable and giving similar values of E_A as the other conventional methods. This revised version was published online in August 2006 with corrections to the Cover Date.     

冷绝缘超导电缆绝缘材料测试综述

绝缘材料在液氮中的各种性能将直接影响到冷绝缘高温超导(HTS)超导电缆的质量。对四种绝缘材料:电缆纸、聚丙烯层压纸、聚酰亚胺薄膜和低密度聚乙烯薄膜在常温和低温下的电阻率、介电常数、介质损耗角正切、低温介电强度和局部放电进行实验研究和对比,得到了有价值的数据。     

改进RCF算法的电缆绝缘层边缘检测

目前电缆绝缘层厚度检测算法主要采用图像处理技术提取出绝缘层的边缘轮廓,此类算法存在绝缘层边缘过宽和边缘不连续等问题,影响了后续的检测精度.为提高绝缘层测量精度,新算法基于RCF算法进行改进,在模型的4、5阶段采用空洞卷积,增大模型的感受野;并在侧输出网络加入尺度增强模块(SEM模块)和由浅到深的级联网络,增加侧输出图像...     

用于柔性结构动力特性研究的非接触式激振系统

提出用于杆、梁、板、弦、索等大柔性结构或系统的动力特性和／或振动控制实验研究的非接触激振方法,推导了对称单Ｅ－型电磁系统的激振力公式,介绍了自行研制的以计算机为核心的非接触式激振系统的原理、结构、特性,给出了应用实例     

Simulation and experiments for the Qext of a cavity beam position monitor

The external Q （Qext） of the dipole mode is a key parameter of the Cavity Beam Position Monitor （CBPM）. It determines the amplitude and length of the dipole mode signal. In this paper, Qext of a CBPM whose waveguides were open to the air was simulated and measured, and the results agreed with each other. Then four waveguide-to-coaxial cable adpaters were adjusted and assembled to the CBPM, and Qext remained unchanged. This progress provides a reliable method to evaluate Qext in the physics design without simulating the structurally complex adapters.     

Modeling and testing of static pressure within an optical fiber cable spool using distributed fiber Bragg gratings

Based on the force analysis, we establish a theoretical model to study the static pressure distribution of the fiber cable spool for the fiber optic guided missile (FOG-M). Simulations indicate that for each fiber layer in the fiber cable spool, the applied static pressure on it asymptotically converges as the number of fiber layers increases. Using the distributed fiber Bragg grating (FBG) sensing technique, the static pressure of fiber cable layers in the spool on the cable winding device was measured. Experiments show that the Bragg wavelength of FBG in every layer varies very quickly at the beginning and then becomes gently as the subsequent fiber cable was twisted onto the spool layer by layer. Theoretical simulations agree qualitatively with experimental results. This technology provides us a real-time method to monitor the pressure within the fiber cable layer during the cable winding process.     

交联聚乙烯电缆绝缘材料中电树枝的导电特性研究

利用光学显微观察、局部放电测量和共聚焦Raman光谱分析相结合的方法, 研究了交联聚乙烯(XLPE)电缆绝缘材料中两种典型电树枝的导电特性.尽管具有相似的培养条件, 两种电树枝却呈现出完全不同的形态,其中9 kV下典型电树枝为枝-松枝状, 11 kV下为枝状, 而且电树枝生长及局部放电规律呈现出明显的差异.枝-松枝状电树枝主干通道内存在无序石墨碳的沉积, 根据石墨碳G带与D带的相对强度,估算碳层厚度约为8 nm,树枝通道单位长度电阻小于 10 Ω· μm^-1,足以抑制电树枝内局部放电的发展,电树枝呈现出导电型电树枝特征. 枝状电树枝通道内观察到荧光背景,存在材料劣化的产物,但不存在无序石墨碳的聚集, 通道具有明显的非导电特性而不足以抑制电树枝内局部放电的连续作用. 最后提出了XLPE电缆绝缘材料中导电型和非导电型电树枝的单通道生长模型, 利用等效电路理论对XLPE电缆绝缘材料中两种不同导电特性电树枝的生长机理进行了探讨.     

Simulation and experiments for the Q_ext of a cavity beam position monitor

The external Q (Qext) of the dipole mode is a key parameter of the Cavity Beam Position Monitor (CBPM). It determines the amplitude and length of the dipole mode signal. In this paper, Qext of a CBPM whose waveguides were open to the air was simulated and measured, and the results agreed with each other. Then four waveguide-to-coaxial cable adpaters were adjusted and assembled to the CBPM, and Qext remained unchanged. This progress provides a reliable method to evaluate Qext in the physics design without si...     

Modelling of inextensible cable dynamics with experiments

The recognition of very stiff axial elastic motion compared to the motion in the transverse direction for cable dynamics motivates separation of the axial and transversal dynamics. For certain applications, e.g. real-time model-based control, fast calculation of the transverse motion may be of high importance, motivating the development of numerically efficient software code. Separation of axial dynamics renders possible neglection or simplification of the axial dynamics if appropriate for the system studied. A model is proposed with the assumption of axial inextensible material and negligible bending, torsion and shear stiffness in the cable. Experiments are carried out to verify the model, and the results are compared with simulations. The comparison between the experiments and numerical simulations showed good agreement up to the second frequency range with resonant behavior and the corresponding motion amplitudes.     

斜拉桥架设分析的新算法

斜拉桥各架设几何形态与内力的确定是施行工程控制的重要前提。目前普遍采用的倒拆法数据量大，计算周期长、对大跨度斜拉桥更是如此。本文提出一种斜拉桥架设分析的新算法－－状态比较法。