Optimization — a tool in advanced materials technology

This paper demonstrates the use of simple optimization techniques in the production of two advanced materials - a fibre-reinforced composite laminate and a transformation toughened ceramic - having enhanced mechanical properties. Both example materials are based on a brittle matrix prone to cracking at very low applied stresses. The optimization process aims at altering the microstructure so that the materials have enhanced resistance to crack propagation without any undesirable side effects.     

A probabilistic method for the design of power grounding systems

An improved multivariable, probabilistic method for the safety analysis of power grounding systems is presented. The application of this method is demonstrated in four examples. The first three examples illustrate the practical evaluation of one new and two existing substation grounding grids when the substation is connected to an overhead distribution system. The fourth example ascertains the relative impact of a difference between the S curve of IEC Publication 479 and Dalziel's equation for the allowable body current used in ANSI/IEEE Std 80-1986 on the validity of an exposure model based on the requirements of Std 80. In this example, the statistical data on ground faults have been taken from actual system records. Further possible refinements of the exposure model are discussed     

一种三叉树的存储结构及其基本操作的实现

本文在文献［１］所给出的有关三叉树有其相关概念的基础上，提出了一种新的三叉树存储结构，即“儿子－兄弟链表”方法，并在这种结构下，对三叉树的基本操作的实现算法进行了较详细的讨论。     

JETS,PLUMES AND BUOYANT JETS IN STATIC ENVIRONMENT

Turbulence represents an essential aspect in atmospheric and oceanic circulations.In particu-lar,it is a preponderant factor in the dispersion of pollutants of artificial or natural origin.Thevertical turbulent jets,plumes and buoyant jets discharging into static environment is one of themost important and basic flow patterns related with the environment pollution.These flows havenumerous important applications,for example,thrust augmentors,waste disposal plumes fromstacks and combustion systems,and significant problems of turbulent diffusion.     

EXPERIMENTAL STUDIES AND NUMERICAL CALCULATION ON TURBULENT BOUNDARY LAYER OF WATER FLOW ALONG CURVED SURFACE

This paper will introduce experimental studies and numerical calculation onturbulent boundary layer of water flow along curved surface in our country in recent years.Onthe basis of the experimental studies,the effects of curvature and roughness on velocitydistribution and pressure distribution and the change of turbulent flow boundary layer onoverflow bucket concave surface is discussed.We proposed the empirical formula of velocity,pressure and the change of turbulent flow boundary layer on outlet bucket concave.According tothe momentum principle,we have deduced the momentum integral equation full water depthboundary layer and using the element as control unit inside the boundary layer on concavesurface of bucket.Combining with continuity equation,we have computed the boundary layerdevelopment on the bucket of a spillway.Compared with the field experimental data,thecalculation results are available.Under polar coordinates,a mathematical model for simulatingtime-averaged flow characteristics in concave surface of bucket is established.The turbulent flowfield on concave surface of bucket is calculated by SIMPLE method and this mathematicalmodel.The flow velocity field,pressure field,distribution of turbulent kinetic energy,distribution of turbulent energy dissipating rate and distribution of shear stress are available.Thecalculation value is consistent with measured test data.     

Cardiorespiratory effects of conventional and high frequency ventilation in rabbits with bilateral pneumothoraces and surfactant depleted lungs

We compared high frequency ventilation (HFV) to conventional mechanical ventilation (CMV) under normoxic and normocapnic condition in surfactant depleted rabbits with bilateral pneumothoraces. We hypothesized that lower airway pressures would be required with HFV under these conditions. We applied CMV and HFV in 8 anaesthetized rabbits with a prototype ventilator at frequencies of 30, 100, 200, and 300 cycles/min. A positive end-expiratory pressure (PEEP) just below the pressure sufficient to open the air leak from the pneumothoraces was applied at all frequencies. Airway pressures, gas exchange, heart rate, and mean arterial pressure were recorded. Peak airway pressure decreased significantly from 2.50 to 2.10 kPa when the frequency of ventilation was increased from 30 to 300 cycles/min. There were no significant changes in mean airway pressure, PaO2, arterial pH, heart rate, and mean arterial pressure when HFV was compared to CMV. In conclusion, during HFV peak airway pressures measured at the mouth were decreased. Our ability to maintain adequate gas exchange in the face of ongoing pulmonary air leaks may reflect lower alveolar pressures.     

智能工作站主机的MMPIS实验模型研究──一个全互连式结构MMPIS硬件环境的设计与实现

本文介绍中日国际合作开发研究的Ａ１型智能网（Ａ１型ＩＮ）智能工作站（ＩＷ）主机的并行推理硬件结构的实验模型设计与实现，给出了一种并行推理硬件支持环境实现方案和该方案在实现中若干问题的解决方法。     

旋风分离器减阻杆对流场的影响

在研究发现旋风分离器减阻杆的基础上，研究了减阻杆对流场的影响，发现了减阻杆使切向速度分布趋于平缓、轴向速度上升峰值内移、径向上压力梯度减小、轴向上中心区从逆压梯度变为顺压梯度等重要规律，从而为分析旋风分离器减阻杆的减阻机理提供了依据。同时本文还首次发现旋风分离器入口附近有近２４％的短路流量，提出设法减小这部分短路流量是提高分离效率的一个研究方向。     

Study and design of step-index channel waveguide bends withlarge-angle and low-loss characteristics

By using micro-prisms, improved three-dimensional (3-D) bends of the embedded and buried waveguides of step-index profile are proposed. A simple phase compensation rule for the optimal design of the micro-prism is also presented. Through the simulation of 3-D semivectorial finite-difference beam propagation method, the transmission characteristics of the improved bends are shown to have been enhanced dramatically as compared with those of the conventional ones. Even for a bend angle of as large as 10°, the normalized transmitted power can still be greater than 95%. These results of 3-D bends are then compared with those of the two-dimensional (2-D) ones which are simplified from 3-D structures by the effective index method, and physical explanation of the discrepancy between the 3-D and 2-D results is introduced. The influences of waveguide structures and prism parameters on the transmission characteristics are discussed in detail. Some criteria for the design of large-angle low-loss 3-D improved bends are also accessed     

冠心病患者循环血中内皮细胞、内皮素和6－酮－前列环素F_（1a）的动态变化及意义

以循环内皮细胞（ＣＥＣ）作为血管内皮细胞（ＶＥＣ）损伤的指示物，以血浆内皮素（ＥＴ）和前列环素（ＰＧＩ２）反映ＶＥＣ的功能变化，对８５例冠心病患者与３０例正常人进行对比研究，并对５０例不稳定型心绞痛及２０例急性心肌梗塞进行了动态观察．结果表明：冠心病外周血中ＣＥＣ、ＥＴ明显升高（Ｐ＜０．００１），ＰＧＩ２明显下降（Ｐ＜０．００１），尤以不稳定型心绞痛和急性心肌梗塞更显著，与病情的严重程度相一致．提示冠心病ＶＥＣ损伤，以及它所分泌的内皮源性舒缩因子失平衡参与了冠心病的病理过程。