同轴电缆的时域反射技术及其在工程中的应用

通过研究阶跃电压信号因电缆的阻抗变化而引起的反射规律,推导出了在多个强间断变化阻抗的情况下,阻抗的相对变化量与反射电压的关系,以及同轴电缆几何尺寸变化与电缆传输阻抗之间的关系。指出在小变形的假设下,它们之间存在着理想的线性关系。同时,举例说明了同轴电缆的时域反射技术在交通工程中的应用。     

A STRUCTURAL ANALYSIS OF THREE-DIMENSIONAL BRAIDS

This paper describes a study of three-dimensional braids produced by a four-step 1 × 1 method. An analytical approach is employed in conjunction with experimental investigations to establish the relationship between the braid structure and braiding parameters. Based on microscopic observations, we divide a three-dimensional braid structure into three representative regions, i.e., the interior, surface and corner, and treat the three regions, respectively. Three types of microstructural unit-cell models are then established. The surface characteristics and the relationship between the interior and surface unit-cells have been derived. Good agreement has been obtained between the calculated and measured values of fiber volume fraction of the braided composite samples.     

低扭矩环锭纱的结构分析

从纤维在空间上的三维形态以及在纱线横截面上的分布分析了低扭矩环锭纱中纤维的三维结构特征.研究结果表明,低扭矩环锭纱中大量的纤维轨迹呈非同轴异形螺旋线,其螺旋轴线与纱线轴线不一致,且螺旋半径不断显著变化,同时,很多纤维片段的螺旋线方向与纱线正常捻度方向相反.此外,低扭矩纱线中纤维在纱线横截面上的分布较为集中,有利于拉伸变形时纤维同时受力.低扭矩环锭纱的这些结构特征揭示了其独特的物理性能,即低残余扭矩、低捻度、高强力.     

Data Analytical Techniques for Surface Texture Characterization of Knitted Fabrics Based on Laser Triangulation Scanner

The paper presents a study of surface texture character-ization of knitted fabrics during simulated wear based onlaser-scanned profiles.The three-dimensional profilewas obtained by scanning the fabric surface using the la-ser trlangulation technique.The analytical techniquesused to derive quantitative parameters Included statisticalanalysis,fractal analysis,and Fourler analysis.     

ANISOTROPY OF THE KERATIN FIBRE COMPOSITE

This paper presents a composite model of the natural keratin fibres (wool and hair) whichconsists essentially of isotropic viscoelastic filaments, oriented parallel to each other in the fibreaxial direction, embedded in an isotropic viscoelastic matrix. The model accurately fits the exper-imental data on the fibre axial stress relaxation moduli and provides upper and lower bounds forthe initial/final values for the fibre transverse tensile and shear stress relaxation moduli andtransverse Poisson's ratio. The partially water penertrable filament phase of the composite modelis identified as the microfibrils in the fine structure of keratin. The strong anisotropy of keratinsin mechanical properties and hygral/thermal expansion is analyzed in terms of composite struc-ture and mechanical as well as the thermal/hygral properties of the two constituent phases.     

织物应变传感器的性能指标及评价方法

基于相关的国家标准,类似工业产品以及其用途对织物应变传感器的性能指标进行评价,采用松弛时间和反应时间作为评价大应变型传感器的指标.并给出关键性能的评价方法,这些评价方法也适用于其它类型的织物应变传感器.基于这些评价方法,对新开发的织物应变传感器进行了测试,结果表明,该传感器能在20%的应变范围内稳定工作,同时具有高灵敏度(应变系数约43),低滞后(6.25%),相对短的松弛时间和反应时间,以及良好的重复性和线性度.该传感器有望在医用、运动服装以及康复治疗等方向得到应用.     

MODELING OF LIGHT SPECULAR REFLECTION FROM PLAIN-KNITTED FABRICS: A THREE-DIMENSIONAL ANALYSIS

The paper applies a mathematical model[1] for specular reflection to plain-knitted fabrics by using a three-dimensional analysis. Computer simulation of goniophotometric curves is generated based oa the model. Correction factors are introduced by taking into consideration of geometry of the instrument used. Comparison between the simulated and the measured curves of a straight monofilament yarn with various orientation angles is carried out and reasonable agreement has been obtained.     

Improvement of Linen Fabric Wickability by Low Temperature Plasma Treatment

Low temperature plasma treatments were applied to linen with oxygen and argon, various level of discharge power and exposure time. Tbe fabric weight loss increased with the exposure time. Their effects on surface chemical properties and morphology of flax fiber, and fabric wickability were investigated. X - ray photoelec-tron spectroscopy discovered that the surface oxygen content of the plasma treated sample was increased. Formation of voids and cracks on the fiber surface was revealed by the scanning electron microscopy. Fabric wickability first was increased and then decreased with the prolonged exposure.     

织物电子器件及系统的发展现状、科学问题、核心技术和应用展望

织物电子学研究对象是具有产生、传输、调制或测量等电子功能的纤维或纤维集合体.织物电子系统通常由织物电子器件和微电子器件混合互补集成而成.它们作为可穿戴系统的一个重要分支,可为人类提供多种功能,如感知、驱动、自适应、交流、自我修复、记忆、学习等,而不影响系统本身的服用性.本文从织物电子器件和系统的定义出发,阐述了不同类别...     

Research and Application of Polymer Nanofibers

Nanometer materials include roughly nanoparticle,nanotube, nanowire, nanofiber, nanofilm andnanoblock, among which nanofiber is defined asmaterial with nanometer-sized diameter and longerthan 1 micron in length. The research development of