Schottky barrier heights of contact metals to p-type ZnSe

Schottky barrier heights (SBHs) of a variety of metals (In, Cd, Nb, Ti, W, Cu, Ag, Au, Ni, Pt, and Se) contacting to p-ZnSe grown by a molecular beam epitaxy method were determined by analyzing capacitance-voltage (C-V) and/or current density-voltage (J-V) curves. The SBH values of the Au and Ni contacts were determined from intersections of straight lines of the C⁻²-V curves to be 1.23 and 1.13 eV, respectively. The J-V calculations provided a large SBH value of 1.2 ± 0.1 eV for a variety of metals, indicating that the Fermi-level could be pinned at the contact interface. Reduction of the SBH values to a level lower than 0.4 eV and/or increase of doping concentrations to a level higher than 10²⁰ cm⁻³ are essential to obtain an ohmic contact with contact resistivity of around 10⁻³ Ω·cm².     

A theoretical and photoelastic contact stress analysis relevant to orthopaedic knee prostheses

This study is based on a theoretical and photoelastic static contact stress analysis, relevant to the design of the plastic tibial plateau in an orthopaedic knee prosthesis. It involves the review of existing theoretical analyses concerned with the contact mechanics of layered elastic systems and, where possible, the validation of any relevant findings using two dimensional photoelasticity. Significant findings include the identification of a general minimum recommendable design thickness for the plastic tibial plateau, the endorsement of using the Hertzian contact theory to predict contact stress levels in the tibial plateau of certain knee implants and the slight improvement in contact conditions in the plastic when the plateau is perfectly bonded to its supporting metal tray.     

On an invariance principle for unilateral contact at a bimaterial elastic interface

This paper examines the axisymmetric elastostatic problem related to the unilateral receding contact at a pre-compressed smooth bimaterial elastic interface. The separation at the interface is caused by the action of axisymmetric stress fields of unequal magnitude, which are applied at any location of the separate halfspace regions. The analysis of the problem focuses on the determination of the zone of separation as a function of the pre-compression, the magnitudes and locations of the axisymmetric stress fields inducing the separation, and the elasticity characteristics of the halfspace regions. It is found that the radius of the separation zone can be evaluated in explicit form. In the particular instance when the loadings applied at the surface of the halfspace regions are equal in magnitude and distribution, the analysis reveals that the radius of the separation zone is independent of the elasticity properties of the halfspace regions and can be evaluated in exact closed form.     

离子色谱技术在钻井现场的应用研究

将离子色谱技术(IC)应用于钻井现场的钻井液滤液分析,从而获取所钻井钻遇地层的可溶性矿物的性质、地层水的类型等资料信息。离子色谱技术在这一领域的应用尚属探索阶段,但通过现场两口井的试用已见到较好的应用效果,文章简介了该技术的应用前景及价值,如:确定油水界面的位置及指导钻井液的调配、确保井下安全等。这方面的论述,对分析化验仪器向井场转移实现多手段综合分析具有一定的促进作用。     

X射线聚束透镜原理及其应用

本文阐述了一种新型的Ｘ射线聚束装置─—Ｘ射线透镜的聚束原理。给出了透镜的基本设计方法，并对它应用于Ｘ射线光刻研究领域的前景作了展望。     

同轴型光电器件的研究开发

本文简要地介绍了武汉电信器件公司正在研究开发的同轴型光电器件，新的器件的工艺与结构特点以及主要技术指标、使用前景。     

梯度折射率棒中传播的高斯光束轨迹解析解及其存在条件的讨论

本文提出光束轨迹方程的一般解，导出解析解的存在条件，推广了文献［１］的光线传播理论，文中以一特定梯度折射率棒为例，讨论了高斯光束在棒中的传播特性。     

Resilient metal spring network silicone-matrix composite for separable interconnections

Resilient metal spring silicone-matrix conducting composites for separable interconnections in electronics were fabricated by the impregnation of silicone into a preform comprising randomly oriented C-shaped Cu-Be springs and a small proportion of Sn-Pb solder, which served to connect the springs at some of their intersections. Composites containing 6.1-9.8 vol.% total filler exhibited volume electrical resistivity 0.5-1.0 mΩ.cm and contact resistivity (with copper) 11-17 mΩ.cm². A compressive stress of about 30 kPa was needed for the low contact resistivity to be reached. The volume 17-26% and the contact resistivity increased by 5% after heating in air at 130-150°C for seven days. Composites containing <9 vol.% total filler showed no stress relaxation for seven days at 6.0% strain.     

Thermal Diffusivity in Supercritical Fluids Measured by Thermal Lensing

Thermal diffusivities of supercritical CO₂ and C₂H₆ were determined over a wide density range with a photothermal technique. The thermal lens, formed by the degradation of the absorbed light energy as heat by the sample, allows the employment of a nonequilibrium method in the critical region. Controlling the refractive-index gradient, i.e., a density gradient, perturbations can be maintained at levels where convection is negligible. An easy-to-operate setup allowed us to measure thermal diffusivities in the density ranges 5 to 20 mol·dm^–3 for CO₂ at 308 and 313 K and 2 to 12 mol·dm^–3 for C₂H₆ at 308 K with a standard precision of 15%.     

Thermography of aged contacts of high voltage equipment

New developments in diagnostic tools and systems are necessary for a reliable and economic evaluation of the condition of equipment in power systems. In a research project a tool for the condition of contacts of centre break disconnector, which is used under normal operation by the aid of a thermography measurement system, has been developed. In this paper, an overview about the laboratory investigation of the temperature load behaviour and the environmental influence on-site for new and aged disconnector contacts are given. A condition evaluation tool for contacts, which was the aim of the project, has been created. The basic method for the evaluation is presented, and also two additional easements for a fast identification of suspect contacts are presented. With this evaluation tool and the usage of a thermography based measuring system, a condition based maintenance strategy can be applied, whereby an early detection of damages is possible and so power quality and reliability increase.