An Investigation of Electrical Contacts for HigherManganese Silicide

Five metals with large work functions including Co, Ni, Cr, Ti, and Mo and two silicides including MnSi and TiSi₂ were examined to determine the best contact material for the thermoelectric material higher manganese silicide (HMS). Three-layer structures of HMS/contact/HMS were prepared in a sintering process. The contact resistance was measured versus temperature. The structures were subjected to x-ray diffraction and energy-dispersive x-ray spectroscopy examination. Thermal stability of the structures was determined by heating the samples to 700°C for different time intervals. The pure metals failed to make reliable contacts due to poor mechanical and chemical stability at high temperatures. In contrast, the metal silicides (MnSi and TiSi₂) showed superior chemical and mechanical stability after the thermal stability test. The observed contact resistance of MnSi and TiSi₂ was within the range of practical interest (10^?5????cm² to 10^?4????cm²) over the entire range of investigated temperatures (20°C to 700°C). The best properties were found for the nanograined MnSi, for which the resistance of the contact was as low as 10^?6????cm².     

电连接器接触件优化设计研究

电连接器的接触件（插针、插孔）是航天电子元器件的关键零件,是电子设备信号传输的直接载体,起着把信号从电连接器的输入端传送到输出端的作用,其接触性能的可靠与否,直接影响着信号的传输。以提高航天电子元器件电连接器的接触可靠性为研究目标,通过基于MSC系列软件,用该软件自带的PCL语言开发的仿真系统,对接触件的性能参数进行计算机仿真分析,并通过实例验证,最终达到优化接触件设计的目的。     

Quantitative Gait Evaluation of Hemiplegic Patients Using Electrical Stimulation Orthoses

Although the functional electrical stimulation orthosis is one of the most recent approaches to the rehabilitation of hemiplegic patients, the quantitative estimate of its influence on the patients walking is not satisfactorily solved. In this communication the variables necessary for gait evaluation are defined and two quantitative methods for their interpretation are given. The second method was tested on eight hemiplegic patients. The results show the applicability of the described techniques of evaluation.     

便携式通讯终端中电触点磨损的研究

分析了便携式通讯终端中PCB镀金电触点的表面磨损情况。连接器簧片与PCB触点之间相对运动造成的磨损加剧了污染,是造成接触失效的主要原因之一。磨损过程为先粘结再擦伤,最后镀金层被磨穿。磨损碎屑被逐渐推到磨损区端部与尘土、摩擦聚合物混合聚集在一起。触点表面磨损的主要方向和磨损区尺寸取决于触点的配合结构。研究结果为建立便携式通讯终端中镀金电触点失效模拟奠定了基础。     

Electrical Characteristics of Metal Contacts to Laser-Irradiated N-Polar n-Type GaN

Electrical characteristics of metal contacts to a laser-irradiated thin-film N-polar n-type GaN surface are investigated. It is shown that the laser irradiation of the N-polar n-GaN results in a significant increase (as high as $hbox{3.0} times hbox{10}^{20} hbox{cm}^{-3}$) in the electron concentration and a decrease in the Schottky barrier height by 0.05 eV (0.28 eV), as estimated using Pt-based Schottky diodes (X-ray photoemission spectroscopy). Ti/Al contacts to the laser-irradiated N-polar sample exhibit an excellent Ohmic behavior with thermal stability up to 600 $^{circ} hbox{C}$, indicating that the laser irradiation treatment can be a very promising technology in practical applications.      

基于层次分析法的软件缺陷评估方法设计

随着计算机技术不断发展,软件已经深入到各行各业.软件缺陷是影响软件运行的重要因素,会对软件的正常运行产生不同程度的影响.不同等级的软件缺陷将会导致软件异常、崩溃,甚至危害系统安全.因此,对软件缺陷的评估非常重要.基于此,提出一种评估软件缺陷的方法,结合软件缺陷特征构建一个评判指标体系,并集合层次分析法,设置软件指标权重...     

An Alternative Method for SU-8 Removal Using PDMS Technique

An alternative method for SU-8 removal is proposed.Instead of directly using SU-8 microstructure as the electroplating mold,a polydimethysiloxane (PDMS) replica is employed.The metallic micromold insert obtained through this method can be easily peeled off from the PDMS replica,meanwhile with high resolution and smooth surfaces.     

触点镀金材料的自然腐蚀和电接触特性研究

由于国内环境污染严重,镀金表面经过长期室内自然暴露后生成了大量呈岛状离散分布的腐蚀物。腐蚀物由处于中心的腐蚀核及环绕的腐蚀晕圈组成,腐蚀核下是微孔。在镀金表面的腐蚀物上进行微动试验,发现较薄的腐蚀晕圈同样会造成高且波动的接触电阻,随微动周期增加,腐蚀物被推开后电阻降低。加大接触正压力,初始接触电阻降低,波动减弱,较少微动周期后电阻降为正常值。由于腐蚀晕圈远大于腐蚀核在表面覆盖的面积,因此腐蚀晕圈上的高电阻及其不稳定性造成电接触失效概率大大提高。     

球面镜像法的讨论

镜像法是静电场边值问题中的重要方法,是电磁场教学中的重点之一.本文对球面的镜像法展开讨论,通过教学中得到的反馈和总结,以唯一性定理为基础,使用待定系数法,重新推导了球面镜像法的镜像电荷及其摆放位置.本文推导使用更一般的假设,推导过程更详细,可以作为"电磁场与电磁波"课程的教师和学习者有益的参考.     

Evaluation of the Schottky Barrier Parameters in the Micron-Size Metal-Semiconductor Contacts

We show that under certain conditions the submillimeter wave detector response of a Schottky barrier diode is a linear function of applied bias and allows evaluation of the barrier height and the near-surface doping level of semiconductor in the micron-size Schottky barrier contacts.     

用博奇编码的方法制作缺陷结构和复式结构的二维光子晶体

提出了一种利用计算机产生和再现具有缺陷结构和复式结构的二维光子晶体的菲涅尔全息图的数字方法。采用博奇编码方法，应用C语言和Matlab语言的混合编程下实现全息图的制作，并直接应用数字滤波技术消除了虚象和零级象，模拟再现出实象。     

Two-Dimensional Metallic Photonic Crystal with Point Defect Analysis Using Modified Finite-Difference Frequency-Domain Method

We have derived a modified finite-difference frequency-domain (FDFD) algorithm for two-dimensional (2-D) metallic photonic crystal (MPC) analysis. Using this method, the numerical results for the transverse-electric (TE) and transverse-magnetic (TM) modes in square and triangular lattices are in excellent agreements with those from other method. Then the correspondence of the band gaps between a unit cell and a supercell is demonstrated. Furthermore, by comparing the field distributions of the defect modes in a point defected MPC and a point defected dielectric photonic crystal (DPC), it is found that the defect MPC has a higher degree of localization, which means that MPC is preponderant for resonator and waveguide applications in millimeter wave and sub-millimeter wave bands.      

Modeling Electrical Properties of Gold Films at Infrared Frequency Using FDTD Method

The finite-difference time-domain (FDTD) algorithm is applied to analyze the electrical properties of gold films, whose relative permittivity is described by the Lorentz-Drude model in infrared and optical frequencies. The skin depth and reflectivity are calculated using the frequency-dependent FDTD method. The results are compared to analytical solutions and an excellent agreement is reported.     

电子浆料用球形银粉的制备

介绍了化学沉淀法生产球形银粉的工艺技术,采用该工艺制备的球形银粉具有良好分散性、合适的粒径、适当的比表面积,可以广泛应用于电子浆料.     

Performance Evaluation of Trellis Code Modulated oDQPSK Using the KLSE Method

A direct detection optical differential quadrature phase-shift keying (oDQPSK) system with trellis coded modulation (TCM) is proposed and analyzed. From the results obtained for the symbol-error rate, it is observed that the proposed oDQPSK-TCM system can perform about 5 dB better than the uncoded oDQPSK system. Optical signal-to-noise ratio penalty due to first-order polarization-mode dispersion of the proposed oDQPSK-TCM system is evaluated and compared with that of unequalized as well as electrically equalized oDQPSK systems.     

Arrhenius 程应用新方法研究

提出了一种快速评价电子元器件的新方法,该方法具有快速、准确、成本低、效率高等优点.利用Arrhenius方程,能快速准确地确定元器件退化的失效敏感参数和退化机理;可对单样品求出与失效机理相关的失效激活能和寿命;通过多样品试验,可得到寿命分布、寿命加速特性和失效率等可靠性参数.以DC/DC电源变换器和高频小功率管3DG130为例,通过实验与现场数据的对比,证明了新方法的正确性和有效性.该方法适用于失效率优于10-7/h(λ＜10-7/h)的高可靠性产品的定量评价.     

Radiation Field Limitation of Spherical Reflectors Using Gregorian Correctors

Use is made of the Fourier integral to derive an expression for the radiation field of spherical reflectors which are corrected for spherical aberration with the use of a subreflector. Calculations for some cases of interest show the sidelobe radiation to be 5.6 dB higher than in a uniformly illuminated aperture.     

无模糊球面天线阵设计方法

基于测向天线阵列阵列流形上方向向量的空间距离,以球面天线阵为例,提出了一种用于无模糊阵列信号处理测向的有向天线元阵列设计方法。该方法不需要根据不同阵列的阵列流形上方向向量的空间距离的解析式进行复杂的推倒,而是从计算机模拟的角度对其进行探讨。该方法具有简单、灵活、稳健、可移植性强等特点。     

利用多维球形星座映射技术降低终端功耗

未来无线通信最富挑战和最重要的问题之一是无线和移动手持设备的功率消耗问题.为了解决终端能量消耗过快增长的问题,同时保证系统信噪比不变,提出利用多维球形星座设计来代替立方平面的星座映射.仿真结果证明,多维球形星座设计在提高系统抗干扰的同时也降低了能耗.