关于无限棒束间流动和传热特性的数值研究

应用非线性ｋε湍流模式，采用非正交曲线坐标系下求解三维ＮＳ方程的非交错网格有限体积方法，数值模拟了充分发展条件下，三角形排列无限棒束间通道内，不同的几何参数（Ｐ／Ｄ），雷诺数（Ｒｅ）下的流动和传热问题。给出了不同参数下的速度和温度分布以及湍流二次流动，分析了几何参数、雷诺数及二次流对棒束内流动和传热特性的影响，得到了不同参数下通道的摩擦系数和Ｎｕｓｅｌｔ数，并与经验关系式作了比较     

面向对象的管理信息系统分析与设计

本文对面向对象方法（ＯＯ）应用于ＭＩＳ系统开发中的诸多问题进行了较详尽的讨论，提出了ＯＯ对象在管理应用领域存在管理生命周期（ＭＬＣ）的新思想，并将该思想应用到面向对象的ＭＩＳ系统分析与设计中，取得了较好的效果。     

功能确定的离散并发系统的Petri网规范设计方法

本文提出概念模型的概念，作为实际问题到Ｐｅｔｒｉ网模型的桥梁，也就是系统的规格说明，概念模型包括功能图，资源图和约束集三部分，由此将系统设计中的功能与环境严格区分开，给出实际问题到概念模型，以及概念模型到Ｐｅｔｒｉ网模型的转换算法，从而构成一个面向功能的系统的Ｐｅｔｒｉ网规范设计方法，通过一制造系统的建模，说明了该方法的规范性和有效性。     

双光子Jaynes－Cummings模型的亚泊松光子统计特性研究

本文利用量子电动力学理论和缀饰原于方法，对双光子Ｊａｍｅｓ－Ｃｕｍｍｉｎｇｓ模型中单模激光场的稳态亚泊松光子统计性质进行了系统研究。结果表明：激光上能级相对泵浦参量Ｘａ具有一个确定的阈值Ｘａｔ；当Ｘａ＞Ｘａｔ时，光场呈现亚泊松光子统计；而当Ｘａ＞＞Ｘａｔ时，光场将呈现出深度且完全恒定的亚泊松光子统计。     

A variable rate multipulse speech coder for CDMA cellular systems

Variable Rate (VR) speech coders are classified into: source-controlled VR coders where the rate is selected depending on the local character of the speech, and network-controlled VR coders where an external control signal selects the coding rate. The first category benefits from the variable rate channels used by Code Division Multiple Access (CDMA) mobile communications. The second category is indispensable for the right behaviour of the CDMA systems under conditions as high traffic levels. The VR speech coder presented in this communication exhibits both types of control. The source control is achieved by means of a Voice Activity Detector (VAD) and a phonetic classifier. The network control acts on the selection procedure of the multipulse excitation sequence to the synthesis filter. This is the main advantage of our VR MultiPulse speech coder because by means of an external signal the bit rate can be changed only every 4 msec, without transitions or distortions. Considering one-way communication, six different operating rates can be externally selected ranging from 4.8 to 9.1 kbps for the active frames; an average bit rate of 380 bps is required for the noise frames.This work has been partly funded by the Spanish Research National Plan under grant no. TIC92-0800-C05-02 and by Northern Telecom.     

服务器个数随机可变的轮询系统分析

前人关于轮询系统的大量研究均以服务器无故障为前提。本文提出了一种容许服务器个数随机可变的多服务器轮询模型。同时考虑排队延迟与服务器故障／修复的影响，获得了顾客等待时间的平均值公式。     

Three-Dimensional Solution and Experimental Confirmation for the Electric Resistivity Testing of Surface-Breaking Defects in Green-State Powder Metallurgy Compacts

This paper investigates electrostatic voltage distributions around a surface-breaking flaw due to an injected current of known strength. The direct 3-D solution of the voltage behavior over the flawed surface is obtained numerically by the use of a boundary integral formulation. A novel iteration method is applied to solve the resulting electrostatic integral equation for the unknown surface voltage distribution. In addition to investigating the sensitivity of different flaw sizes to the observed surface voltage distribution, important issues such as suitable probe spacing and current flow orientation are studied. For sufficiently small surface-breaking flaws, a simple image source model is developed to evaluate the voltage response of hairline cracks. The model is tested by comparing it with the developed numerical solution. Experiments aimed at establishing the validity of the modeling approach show remarkable agreement with the theoretical model.     

浅成热液金矿成因研究现状与讨论

浅成热液金矿业已成为最重要的金矿类型之一本文探讨了浅成热液金矿成因研究方面若干基本问题:浅成热液金矿的概念和特征、矿床的分类、矿床成因模式。重新厘定了浅成热液金矿的概念.尝试性地按成矿深度和成矿作用方式—斌矿地质环境(容矿岩系)—成矿物理化学条件的分类原则, 将浅成热液金矿分成两大类四种类型:热水沉积岩型、热水火山岩型、浅成热液型和卡林型。前两者为热水沉积型,后两者为热液交代型。在透视现有各种成矿模式的建模依据和存在问题的基础上,指出了今后浅成热液金矿成因研究的发展方向。     

一种低损耗声表面波滤波器

本文从声表面波滤波器的基本原理出发，介绍了我们研制的低损耗声表面波滤波器，给出了实验结果，经实验证实有较好的频率特性。     

单电子晶体管电导振荡及其解释

文中概述了单电子晶体管电导振荡的特点并进行了理论解释，进而讨论了介观电容及电容谱的概念。