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。     

从文本语言看张爱玲的艺术感觉

引言作家的艺术感觉，是与作家的天赋、才清、个性等主体因素密切联系的。一个作家具有什么样的艺术感觉，将直接影响他（她）的叙述风格，并最终奠定他（她）的作品灼基本风貌。因为，艺术感觉几乎贯穿于艺术创造的全过程，作家主观世界与客观世界的碰撞与融合，都有赖于艺术感觉进行整理、凝聚、提炼和加工，然后以“外显”的形式呈现出来。张爱玲具有超凡的艺术感觉，那是毫无异议的。作为一名才华横溢的女作家，她在青春年华即已写出了空前绝后的凄艳的传世佳作。她的名字虽不见于目前的中国现代文学史，但她“在文学上的功过得失，是客…     

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.     

热致相分离法制备丙烯腈-丙烯酸甲酯/纳米TiO_2复合膜及膜性能研究

以自制的可熔融丙烯腈(AN)-丙烯酸甲酯(MA)共聚物为基体,以碳酸乙烯酯(EC)与柠檬酸三乙酯(TEC)为复配稀释剂,采用热致相分离法(TIPS)制备丙烯腈-丙烯酸甲酯(AN-MA)/纳米二氧化钛(TiO2)复合膜。借助场发射扫描电子显微镜(FESEM)、X-射线衍射仪(XRD)和万能试验机,从微孔膜的力学性能、水通量、孔隙率、晶型等方面对膜的结构与性能进行表征。结果表明,添加TiO2纳米粒子可以显著提高AN-MA微孔膜的机械强度和水通量。随着TiO2含量的增加,微孔膜的机械强度先增加后降低,TiO2质量分数为0.1%时,断裂强度最高可达8.0 MPa,比未添加TiO2的样品高36%。纳米TiO2的加入一定程度上抑制了大孔的产生,微孔膜结构更加均一。随着凝固浴温度的升高,微孔膜的力学性能逐渐提高,通量出现下降趋势。     

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.     

Thermal Stability of Poly （acrylonitrile-methyl acrylate） Copolymers

Poly （ acrylonitrile-methyl acrylate） copolymer was synthesized by water depositing polymerization and has a typical feed ratio of 85/15. And then 1 - 3 wt% lauryl alcohol maleic anhydride （LAM） was adopted as stabilizer to mix with the acrylonitrile based copolymer. The mixtures were characterized by using Fourier Transform Infrared Spectroscopy （FTIR）, Nuclear Magnetic Resonance （1 H NMR ）, Gel Permeation Chromatography （ GPC ）, Differential Scanning Calorimetry （DSC）, optic microscope and Ubbelohde viscosimetryr etc. The melting point （Tm） and glass transition temperature （Tg） of the 85/15 AN/MA copolymer mixed with LAM all decrease with the increase of stabilizer content. The lowest Tg and Tm were 116.1℃ and 209. 1℃ respectively at the heating rate of 100℃/min when the content of LAM is 2 wt%. The 85/15 AN/MA copolymer mixed with 1 - 3 w t% LAM possess good thermal stability up to 30 min at 220 ℃.     

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.     

耐高温相变材料微胶囊及熔纺高储热量储热调温纤维

介绍了一种在15～45℃范围内具有高储热量的纤维——储热调温纤维(俗称空调纤维)和一种耐高温相变材料微胶囊(MicroPCMs)的制备技术及应用推广情况。该纤维可显著改善服装的舒适性,对实现"低碳"经济和"低碳"消费、提升服装和建材产品国际市场竞争力具有重大的意义。