Microscopic fatigue processes in a plain-weave glass-fibre composite

This paper focuses on the microscopic damage and progressive failure of a composite reinforced by plain-weave glass cloth under tensile fatigue loading. The fatigue process was divided into three stages like that of multi-directional laminates. It was found that the internal damage at each stage (matrix cracks, debonds in the weft, successive debonds in the warp and ‘metadelaminations’ between warps and wefts) occurred near the cross-over point of the fabric. The modulus decay mechanism was explained by considering the progression of this internal damage. From the end of the first stage to the beginning of the middle stage, a characteristic damage state (CDS) (called a ‘meta-CDS’) was observed. It was found that woven composites have a unit area of damage accumulation (called a ‘unit cell’) and the damage of each unit cell and its distribution control the total fatigue damage of the material.     

Optimal task allocation in hypercube multiprocessor ensembles

Criteria are established to determine the optimal policy for allocating a set of uniform tasks onto a multiprocessor hypercube ensemble. It is shown that the optimal policy depends on the ratio of computation to intertask communication required by the distributed program, and that based on this ratio, tasks should be placed either all on one processor or uniformly distributed over the largest possible hypercube.     

Expectation of LET∞ for a tritium beta particle

The expectation of LET_∞ (unrestricted linear energy transfer) for a tritium beta particle around its parent nucleus in water has been calculated by the use of the energy-range relation of electrons. The amount of energy deposited by a beta particle with a certain initial energy over the interval of one micron at a definite position is obtained from the relation by the calculus of difference, and the probability that the event takes place per decay of tritium is estimated from the energy spectrum of tritium beta particles. The calculated values of expectations of LET_∞ are higher at positions close to the parent nucleus.     

The forward muon detector of the DELPHI experiment at LEP

The layout and construction of the muon drift chambers equipping the end caps of the DELPHI detector are described. The performance of this forward muon detection system, determined from cosmic ray tests and data collected during the first year of LEP operation, is presented.     

全方位为顾客服务

介绍了Dohmen公司的发展过程，目前的状况及公司的宗旨。     

智能化多业务网络

首先从不同角度分析了通信服务商目前面临的环境,包括通信服务业的投资趋势、业务发展趋势、服务提供商的业务收入情况以及用户的需求;接着介绍了朗讯的智能化多业务网络的整体架构和解决方案;其中重点描述了智能化多业务网络在网络传输层、业务控制层和应用层上的智能化以及包括核心网络、城域网络在内的六大解决方案。     

Low-cost modular system of machine-to-computer communication for a flexible machining cell

Cranfield Robotics and Automation Group (CRAG) in collaboration with Texas Instruments (UK) manufacturing systems research group has built a flexible machining cell and established computer integrated manufacturing support facilities to demonstrate a low-cost, modular system of machine-to-computer communication.     

Effects of design parameters on geared two-link mechanisms

The design of a specialized agricultural harvesting machine required the use of a path generation mechanism that was compact, accurate, inexpensive to manufacture and difficult attempts involved the use of a cam and follower, but they were expensive to manufacture and difficult to operate. This paper discusses an alternative method of using a coupled, open loop, two-link mechanism to generate a polygon-like closed path (pseudo-polygon) with an integer number of curved sides and apexes. A complete development of the path and path curvaturei equations are presented. The influence of the design variables on the coupler shape (flatness of each side) is shown in equation and design chart form. An example of a successful application of this design method applied to a plant cutting mechanism is presented.     

二阶系统变阻尼技术研究

本文基于测速反馈原理，针对二阶系统提出了两种改变系统阻尼的方法。通过适当改变测速反馈系数，可使闭环系统的阻尼比按期望的规律变化（阻尼比可以为负），从而可显著地加快系统的输出响应，使系统的动态性能大为改善。文中提供了仿真算例。