High resistivity measurement of SiC wafers using different techniques

To establish fast, nondestructive, and inexpensive methods for resistivity measurements of SiC wafers, different resistivity-measurement techniques were tested for characterization of semi-insulating SiC wafers, namely, the four-point probe method with removable graphite contacts, the van der Pauw method with annealed metal and diffused contacts, the current-voltage (I-V) technique, and the contactless resistivity-measurement method. Comparison of different techniques is presented. The resistivity values of the semi-insulating SiC wafer measured using different techniques agree fairly well. As a result, application of removable graphite contacts is proposed for fast and nondestructive resistivity measurement of SiC wafers using the four-point probe method. High-temperature van der Pauw and room-temperature Hall characterization for the tested semi-insulating SiC wafer was also obtained and reported in this work.     

针梁台车在大花水水电站引水隧洞混凝土衬砌施工中的改进

大花水水电站引水隧洞由于前期开挖工期略有滞后，为加快施工进度，结合全圆断面的施工特点，大部分引水隧洞采用了全圆针梁穿行式钢模台车进行混凝土衬砌。通过各参建单位对针梁台车的运用和改进，有效地提高了引水隧洞混凝土的衬砌速度，并确保了工程质量。     

Many-Body Terms in van der Waals Cohesion Energy of Nanotubes

We have developed a model for the calculation of van der Waals force for layered systems with axial symmetry. Our result can be applied to compute the cohesion of a carbon nanotube to a substrate, the cohesion between nanotubes, and between shells of multiwall nanotubes. We have obtained unusal power laws for the distance dependence of the many-body van der Waals potential.     

免振捣自密实混凝土技术在多层住宅中的应用

介绍了免振捣自密实混凝土的特点和质量控制措施，结合某小区自密实混凝土工程应用实例，阐述了该项施工技术，其经济和社会效益良好，提出了进一步发展该技术的若干设想。     

Φ76mm自动轧管机组穿孔机顶杆小车的改进

通过校核Φ７６ｍｍ自动轧管机组穿孔机顶杆小车的轴承寿命，提出了顶杆小车的改进措施，如重新选配合适的轴承型号，修改有关装配尺寸等。改进后，顶杆小车的使用效果良好。     

连铸转炉钢包电力牵引车的研制

论述研制连铸转炉钢包牵引车的目的、意义、方案的选择及设计计算校核,对技术要点作出了明确阐述.     

Crystalline complex between poly(γ-methyl l-glutamate) and dimethyl phthalate

The crystalline complex between poly(γ-methyl l-glutamate) (PMLG) and dimethyl phthalate (DMP) has been formed in films cast from a solution in dichloroethane. It has the stoichiometry of 1 mol of DMP to three or four residues of PMLG and shows two definite characteristics in X-ray diffraction patterns; one is the large hexagonal unit cell with the edge of around 28 Å and another the ‘extra’ 5.07 Å meridional reflection which can not be interpreted by a PMLG α-helical conformation. The structural examination for the films with various DMP contents is carried out by X-ray, viscoelastic, and d.s.c. measurements and the following structure is proposed for the crystalline complex. Four PMLG are associated to form a group which is hexagonally packed and DMP molecules, located in the gaps between groups, form a specific favourable helical structure along PMLG chains in which the van der Waals stacking of benzene rings of DMP is significant.     

一种通信指挥车的总体设计

从通信指挥车的使用特点出发,讨论了车厢结构设计和通信指挥系统的设计.在车厢设计中,重点对扩展方舱、功能区模块、机架标准化和人性化设计进行了阐述.在通信系统设计中,重点对系统集成、综合布线、电磁兼容设计等方面进行了讨论.     

试论建筑理论研究的目的与方法——以范·德·拉恩的比例理论为例

以范·德·拉恩的比例理论为例,对建筑理论研究的目的和方法进行了探讨,结论是：建筑理论研究的根本目的,是从自然规律中提取若干可以指导实践的基本原则或者＂法则＂;为了获得这些法则,人们通常采用的是隐喻和分类,类比和还原等基本策略;在最指实的地方,往往可以得到一种禅宗所说的＂顿悟＂,从这个意义上说,任何真正的建筑理论都不是以神秘主义为直接目标的.     

谈现代汽车车身塑料件及其涂装

本文详细阐述了现代汽车车身塑料件涂装的功用；并介绍了汽车塑料件涂装的常用涂料与配套、塑料件修补涂装前的准备工作；硬、软质塑料部件修补面漆的喷涂；车用聚丙烯塑料件的喷涂及车内乙烯基塑料件和乙烯树脂顶棚表面的喷涂。