2,3-二氢苯并〔b〕呋喃衍生物的合成

本文对二氢苯并呋喃类杂环化合物的合成方法及其反应机理进行了研究和探讨．在醋酸锰（Ⅲ）存在下，通过分子间氧化自由基环化反应，由亚甲基双乙酰丙酮与１，１－二芳基乙烯合成出２，３－二氢苯并〔ｂ〕呋喃衍生物．     

影响滚子链疲劳寿命的主要因素

对链板材料的疲劳强度、链板孔表面加工质量、链板应力集中、整链预拉强化、链板喷丸强化等影响滚子链疲劳寿命的规律进行了深入的研究，给出了提高滚子链疲劳寿命的工艺参数。     

ATM网络安全通信的研究

文中讨论了ＡＴＭ网络安全通信中的若干重要问题，包括数据加密，加密系统中信元丢失引起的重要同步以及密这理等若干方面。     

Chain Vibration and Dynamic Stress in Three-Dimensional Multibody Tracked Vehicles

A three-dimensional computational finite element procedure for the vibration and dynamic stress analysis of the track link chains of off-road vehicles is presented in this paper. The numerical procedure developed in this investigation integrates classical constrained multibody dynamics methods with finite element capabilities. The nonlinear equations of motion of the three-dimensional tracked vehicle model in which the track link s are considered flexible bodies, are obtained using the floating frame of reference formulation. Three-dimensional contact force models are used to describe the interaction of the track chain links with the vehicle components and the ground. The dynamic equations of motion are first presented in terms of a coupled set of reference and elastic coordinates of the track links. Assuming that the structural flexibility of the track links does not have a significant effect on their overall rigid body motion as well as the vehicle dynamics, a partially linearized set of differential equations of motion of the track links is obtained. The equations associated with the rigid body motion are used to predict the generalized contact, inertia, and constraint forces associated with the deformation degrees of freedom of the track links. These forces are introduced to the track link flexibility equations which are used to calculate the deformations of the links resulting from the vehicle motion. A detailed three-dimensional finite element model of the track link is developed and utilized to predict the natural frequencies and mode shapes. The terms that represent the rigid body inertia, centrifugal and Coriolis forces in the equations of motion associated with the elastic coordinates of the track link are described in detail. A computational procedure for determining the generalized constraint forces associated with the elastic coordinates of the deformable chain links is presented. The finite element model is then used to determine the deformations of the track links resulting from the contact, inertia, and constraint forces. The results of the dynamic stress analysis of the track links are presented and the differences between these results and the results obtained by using the static stress analysis are demonstrated.     

Automated Meta-Control for Adaptable Real-Time Software

The software meta-controller is an online agent responsible for dynamically adapting an application's software configuration, e.g. altering operational modes and migrating tasks, to best accommodate varying runtime circumstances. In distributed real-time applications such adaptations must be carried out in a manner which maintains the schedulability of all critical tasks while maximizing some notion of system value for all other tasks. For large-scale real-time applications, considering all possible adaptations at the task-level is computationally intractable. This paper presents an automated aggregate approach to software meta-control, appropriate for large-scale distributed real-time systems. The aggregate automated meta-control problem is still NP-hard, but it has very practical approximate solutions. Introduced, here, are two very-effective approximation algorithms, QDP and GG, with very reasonable polynomial time complexity. Both algorithms also provide us with upper bounds for optimum system values, useful for deriving absolute, albeit somewhat pessimistic, measures of actual performance. Extensive Monte Carlo analysis is used to illustrate that expected performance for both algorithms is generally suboptimal by no more than a few percent. Our flexible software meta-control model is also shown to be readily applied to a wide range of time-sensitive applications.     

HEDRA: Heterogeneous Distributed Real-Time Architecture

HEDRA, ESPRIT project (nr. 6768), aims to develop a heterogeneous distributed real-time architecture for robot and machine control. This paper describes an open and flexible programming system, as a part of this architecture, that is based on an existing system called VIRTUOSO. The programming system is an evolution of Virtuoso towards the aimed architecture. The work concentrates on the achievement of guaranteed real-time behavior, minimum interrupt latency and transparency of interprocessor data communication.     

珠海发电厂生产数字化管理系统

介绍珠海发电厂生产数字化管理系统(E-PLANT)的结构特点和功能。该系统通过建立OpenPlant实时数据库,在分散控制系统(DCS)和实时数据库之间建立接口,将DCS中约40 000个数字量和模拟量采集至实时数据库,再对实时数据库中的数字量和模拟量进行二次开发利用。已形成涵盖发电厂生产运行、设备管理和生产经营等各管理部门需求的八大系统、20多个功能模块。系统自建成以来运行稳定,在电厂生产管理等方面发挥了很大作用,该系统的成功应用对现代化发电厂的信息化和数字化建设提供了有益的借鉴。     

我国功率型LED产业化关键技术

本文介绍了我国功率型LED产业链三个阶段的关键技术。     

基于GPRS的机车实时监测系统

GPRS(通用分组无线电业务)由于其流量计费、高速传输等特点,正越来越广泛地用于车载监控、电力抄表、气象监测等行业的远程数据传输.本文介绍一种基于GPRS无线通信网络的机车实时监测系统,给出该系统的总体结构以及各单元的主要功能,阐述GPRS在机车无线监测系统中的优势.通过GPRS网络实现车载子系统与地面监测中心之间的通信.该系统已投入实际运行,并取得了良好的效果.     

Fe3(PO4)2固相法合成及其影响因素的研究

锂离子电池正极材料LiFePO4具有良好的发展前景。介绍了采用固相法合成Fe3P(O4)2的方法,并对实验现象进行了理论分析,用扫描电镜表征了实验产物的形貌。结果表明:Fe3P(O4)2的生成温度为200℃,但如果使反应进行完全,则需300℃以上;Fe3(PO4)2共有三种反应机理;温度和原始反应物的晶粒尺寸都会影响生成Fe3P(O42)晶粒的尺寸,温度越高,生成的Fe3P(O42)晶粒就越大,原始反应物的晶粒尺寸越小,生成的Fe3P(O4)2晶粒就越小。