具有任意形状单元离散模型的界面元法

文［１］推出了求解不连续介质体的界面应力元法，并在理论和实例验算两方面论证了该法具有精度好、效率高、适用范围广等优点。通过进一步研究，该法还可适应任意网络离散模型的计算。本文引用自然坐标，实施了任意形状单元的界面元算法，并给出了算例，成果表明，本文的算法可行，其精度也是令人满意的。     

坐标测量机及其应用

随着技术的发展，工业中采用了越来越多的特殊曲线或曲面，采用坐标测量技术的坐标测量机就可以比较好地产生这些曲线或曲面。利用坐标机可以对各种复杂形状的三维零件进行手动、机动或自动测量，通过人机对话，在计算机控制下完成全部测量的数据采集和处理工作。使用坐标测量技术的仪器还有其它形式。例如，使用经纬仪进行探测点瞄准的光学坐标测量系统，可以用非接触的方法对大型设备进行测量；原子力显微镜和隧道显微镜是微观尺寸的坐标机，可以在原子量级上进行测量。坐标机可以测量各种形状工件的几何参数。对任何一个被测对象，测量方…     

智能坐标测量系统的研究

为提高数控坐标测量机的柔性和自动化程度，本文研究了一种利用计算机视觉和图象处理技术与ＣＮＣ－ＣＭＭ相结合而形成的智能坐标自动测量系统，提出了测量机器人的概念。文中给出了该系统使用的工作识别方法、定位定向方法及测量路径自动生成方法，并给出了详细的测量路径生成模式。     

坐标测量机的溯源方法

由于坐标测量机的通用性,不同的测量任务有不同的测量不确定度,长度测量不确定度可以作为坐标测量机溯源的近似方法,但面向任务的校准则是最终的解决方案。文中还介绍了中国计量科学研究院提出的目前条件下的坐标测量机溯源方案。     

多关节坐标测量机的坐标转换和参数标定

对多关节测量机的参数标定方法进行了研究,研究方法主要包括:根据Denavit-Hartenberg方法,在空间坐标转换的基础上建立了六自由度多关节坐标测量机的数学模型,进而讨论杆件间相对位置关系,研究了模型中系统参数及运动参数的标定问题,并设计一种全新的标定球,在此基础上又结合最小二乘法和迭代法的标定方法实现了参数的标定.实验证明运用该标定球能成功地进行系统参数的标定,精度可达到0.05 mm,并通过计算和实验验证了该标定方法的可行性.     

利用4参数法进行北京54坐标至西安80坐标的换算

在分析北京54坐标系统和西安80坐标系统特点的基础上，论述了利用4参数法将54坐标转换至80坐标的方法。     

简介CORDAX坐标测量系统

IntroductionCORDAXCoordinateMeasuringSystemZhuWenboORDAX坐标测量系统是由美国的吉丁斯·路易斯（G&L）公司自动测量与控制集团的谢菲尔德（SHEFFIEID）工厂生产的，它是当今世界上机床与工厂生产自动化系统的第一流生产制造厂商和成套设备供应商。其产品已在美、英、法、德、日、意等国得到大量的应用。目前CORDAX坐标测量系统已在北京、沈阳、丹东、上海、咸阳、成都、昆明、深圳等地的中外合资企业和国有大企业被广泛使用，效果很好。至1993年底销售量已超过1万台。·SUMMIT起精密坐标测量机（CMM）系列SUMMIT系…     

简易双坐标测量仪

工程技术人员在测绘零件时常常遇到这样的问题:有的零件表面或内部有许多孔,测绘非常不便,如汽车发动机的汽缸盖;有的零件结构的外形很复杂,如汽车发动机的化油器等。为此本文介绍一种简易双坐标测量仪。一、测量仪结构如图所示,测量仪结构比较简单,由底座1、角尺2、紧固?..     

有限元新型自然坐标方法研究进展

网格畸变敏感问题一直是当前有限元法难以解决的问题,而新型自然坐标方法的诞生可以在一定程度上对解决这个难题有所帮助。该文介绍了有限元新型自然坐标方法研究的新近进展。包括第一类四边形面积坐标及其应用(单元构造,解析刚度矩阵的建立,以及在几何非线性问题中的应用等);第二类四边形面积坐标及其应用;六面体体积坐标及其应用。数值算例表明:无论网格如何扭曲畸变,这些基于新型自然坐标方法的有限元模型仍然保持高精度,对网格畸变不敏感。这显示了新型自然坐标方法是构造高性能单元模型的有效工具。     

Reminiscence of a teacher and a researcher

Abstract

The names of previous after-dinner speakers at this conference read like a Who is Who of Quantum Optics and Photonics research. When the organizers of this conference asked me to present an after-dinner talk I felt honored by the invitation, but also humbled by joining such a distinguished company. This fact gives me a “Leitmotiv” for my present talk, because being humbled by, and feeling inferior to, all the brilliant minds one encounters in one's career is a necessary occurrence, which most of the younger listeners in this audience have either experienced or will experience. I have witnessed these feelings as advisor to students at MIT. Many of them fear that everything worth doing has already been done. There is a simple answer to this. Do not get discouraged, work harder and you will also make a respectable contribution to science or engineering.     

Ceramesh — a company and a membrane

Claimed as a major advance in microfiltration technology, Ceramesh is an inorganic composite ceramic membrane that can be produced in a flat sheet suitable for use in process-scale crossflow filtration systems. The membrane combines a metal mesh and a ceramic to give strength, formability and both chemical and heat resistance The Ceramesh membrane technology has its origins in work carried out at Alcan Separations in Banbury and has been under development since 1988. Some of the original team had also worked on the development of the Anopore membrane, since commercialised by Anotec, and these close personal links have been maintained. Ceramesh Ltd was formed in 1990 by Alcan and a venture capital company with the aim of speeding the development of the membrane and ensuring its early introduction to the commercial filtration market. These objectives have now been achieved and by the middle of 1992 the Ceramesh membrane has been evaluated for a number of specific applications, been incorporated into a range of commercial filtration equipment, and formally launched into the chemical-process industries at the Eurochem exhibition held in Birmingham in June.     

Separation and slip between a layer and a substrate caused by a tensile load

The paper treats the elastic layer that is pressed uniformly against a half space and is subsequently subjected to a concentrated force tending to induce slip and separation between the bodies. The formulation, based on known results for discrete dislocations, reduces the problem to a coupled system of integral equations which is solved numerically. Various results of interest are given graphically.     

Aberrations from a prism and a grating

Formulas for the wave aberrations introduced into a beam by a prism or a plane grating are derived from the theory of plane symmetric systems. Emphasis is made on the field-dependent aberrations.     

Diffraction of a finite-radius plane wave and a Gaussian beam by a helical axicon and a spiral phase plate

We derive what we believe to be new analytical relations to describe the Fraunhofer diffraction of the finite-radius plane wave by a helical axicon (HA) and a spiral phase plate (SPP). The solutions are deduced in the form of a series of the Bessel functions for the HA and a finite sum of the Bessel functions for the SPP. The solution for the HA changes to that for the SPP if the axicon parameter is set equal to zero. We also derive what we believe to be new analytical relations to describe the Fresnel and Fraunhofer diffraction of the Gaussian beam by a HA are derived. The solutions are deduced in the form of a series of the hypergeometric functions. We have fabricated by photolithography a binary diffractive optical element (a HA with number n=10) able to produce in the focal plane of a spherical lens an optical vortex, which was then used to perform rotation of several polystyrene beads of diameter 5 microm.     

Stress analysis of a strip with a step and a crack

Stress analysis for a strip of which widths are different at the right and left handsides is carried out for before and after occurrence of a crack at a corner of a step. The strip is analyzed as a thin plate bending problem subject to transverse bending and torsion, and as a plane eleastic problem subject to bending in the plane and uniaxial tension. The rational mapping function of a sum of fractional expressions and complex variable method are used. Stress distribution and stress intensity factors are obtained.     

Interaction between a liquid and a cylindrical body touching a wall

An exact solution is obtained for the problem of interaction between the ideal liquid homogeneously moving at infinity and streamlining a round cylinder touching a solid wall.     

MHD flow and heat transfer in a channel bounded by a shrinking sheet and a plate with a porous substrate

This research is concerned with heat transfer and an MHD flow of a viscous incompressible electrically conducting fluid in a channel bounded by a shrinking sheet and an impermeable plate. A fluid-saturated porous substrate of a very low permeability is attached to the impermeable plate. The flow in the channel is induced by the upper shrinking sheet, where a constant suction is imposed. By introducing the similarity transformations, the governing partial differential equations for the flow and heat transfer are transformed to ordinary differential equations which are solved analytically by using the perturbation series method for a small shrinking parameter. Expressions for the velocity distribution, temperature field, skin friction, and heat transfer rate are obtained, and numerical computations are carried out for various parameters. The results are displayed graphically and discussed.     

The interaction between a dislocation and a crack

The solution is given in closed form to the problem. of the elastic field round a dislocatiop ,and a,; crack in any relative position when the field is independent of one of the three cartesian co-ordinates,, The, analysis holds for the most general anisotropy.

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Zusammenfassung Die Lösung wird dem Problem des elastischen Feldes rund um eine Verschiebung und einen Riss in irgendeiner relativen Stellung in geschlossener Form gegeben, wenn das Feld von den drei kartesischen Koordinaten unabhängig ist. Die Analyse gilt fiir die generalste Anisotropie.

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Résumé Le pròbleme du champ de tension élastique autour d' une dislocation et d' une fissure en positions relatives quelconques est résolu sous une forme générale dans le cas d' une champ élastique indépendant d' une des trois coordonnees cartésiennes.L' analyse effectuée couvre le cas de 1' anisotropie la plus générale.

     

Interaction between a cylindrical shell in a fluid and a pulsating bubble

The dynamic behavior of a cylindrical fluid-immersed shell in a pressure wave initiated by a pulsating vapor-gas bubble that develops as a result of the action of laser radiation on the absorbing medium (metal) is examined experimentally and theoretically. The results of the experiments suggest that the amplitude of the shock wave that develops as a result of complete or partial vaporization of the absorbing medium is appreciably smaller than the amplitude of the waves due to pulsations of the bubble that is formed. Experimental data on the pattern of structural deformation are confirmed by calculations. The effect of load simulation on the behavior of the shell is established according to computational data.Translated from Problemy Prochnosti, No. 6, pp. 116–120, June, 1990.