发动机CAD的工程数据库管理系统

论述了发动机ＣＡＤ的工程数据库管理系统（ＧＣＡＤ－ＥＤＢＭＳ）的功能以及在集成ＣＡＤ系统中的核心作用和实现方法，结合具体的工作站联网使用环境，使得ＧＣＡＤ－ＥＤＢＭＳ具有统一管理图形数据和非图形数据的能力，在网络环境下具有分布处理的能力。     

实时通信系统的网络存取协议

本文提出一种基于ＣＳＭＡ／ＣＤ方法新型网络存取协议,为了评价本协议的性能做了大量的仿真实验,并将传统的ＣＳＭＡ／ＣＤ,ＶＴＣＳＭＡ／ＣＤ－Ｌ和ＰＢＣＳＭＡ／ＣＤ三种协议的性能进行了比较。结果表明,ＰＢＣＳＭＡ／ＣＤ协议性能良好。     

1845D，独领风骚

今天你 用 什 么ＣＰＵ 了？Ｐｅｎ－ ｔｉｕｍ３？Ａｔｈｌｏｎ ＸＰ还 是 Ｐｅｎｔｉｕｍ４？ 今天你用什么 内存了？ＳＤＲＡＭ？ ＲＡＭＢＵＳ还是 ＤＤＲ ＳＤＲＡＭ？ 目前搭配Ｐｅｎ－ ｔｉｕｍ４ 的内存有ＳＤＢＡＭ、ＤＤＢＡＭ以及ＲＤＲＡＭ三种，一些玩家会产生这样的疑问：哪种内存才能让 Ｐｅｎｔｉｕｍ ４具有狂飙的速度呢？从理论上来说，ＣＰＵ进行内部数据处理时本身存在着数据传输的带宽，当ＣＰＵ和内存进行外部数据交换时也存在着内存带宽，如果内存带宽可以尽可能地满足ＣＰＵ的数据传输带宽的要求，那么ＣＰＵ性能就…     

一个超文本,面向对象和关系三者统一的数据模型

本文论述了ＥＤＢＭＳ的一个超文本、面向对象和关系三者统一的数据模型－Ｈｙｐｅｒ－ＯＲ，用以全面支持ＣＡＤ／ＣＡＭ和ＣＩＭＳ应用领域整个产品开发周期全过程的数据管理和工具集成任务。     

分布式工程数据库管理系统dEDBMS

随着ＣＡＤ／ＣＡＭ等工程应用的逐步深入，对具有分布式管理功能的工程数据库管理系统的需求日益迫切。为此，在我室自行研制的单用户工程数据为核心管理系统ＥＤＢＭＳ／２的基础上，欠设计并实现了一个分布式工程数据库管理系统－－－ｄＥＤＢＭＳ。ｄＥＤＢＭＳ运行在ＳＵＮ ＴＣＰ／ＩＰ网络环境，基于作者提出的扩展客户／服务器体系结构。针对工程应用之特点，提供远程数据库访问和检出／检入两种操作模式，支持多服务器的自     

CDMA核心网络构成

ＣＤＭＡ核心网络主要由以下几部分组 成： ＨＬＲ／ＡＣ／ＳＣＰ：合一设置的归属位置寄存器／鉴权中心／业务控制点 ＭＳＣ／ＳＳＰ：合一设置的移动交换中心／业务交换点 ＭＣ／ＶＭＳ：合一设置的短消息中心／语音信箱 ＶＬＲ：拜访位置寄存器 ＢＳＳ：基站子系统 ＳＣＰ：独立的业务控制点 ＯＭＣ：操作维护中心 ＩＷＦ：网络互联单元 ＳＴＰ;信令转接点 ＣＤＭＡ网络遵循的空中接口标准协议是ＩＳ－９５,该标准可以分为两个阶段即ＩＳ－９５Ａ和ＩＳ－９６Ｂ,ＩＳ－９５Ａ支持的最高速率为９.６ｋｂｐｓ,ＩＳ－９６Ｂ支持的最高速…     

GHCAD: A Feature-based Design System

ＧＨＣＡＤ：ＡＦＥＡＴＵＲＥ－ＢＡＳＥＤＤＥＳＩＧＮＳＹＳＴＥＭＱｉａｎＸｉａｏｐｉｎｇ；ＸｉａｎｇＷｅｎ；ＺｈａｎｇＸｉｎｇｆａｎｇ；ＺｈｏｕＪｉ；ＹｕＪｕｎＧＨＣＡＤ：ＡＦＥＡＴＵＲＥ－ＢＡＳＥＤＤＥＳＩＧＮＳＹＳＴＥＭ￥ＱｉａｎＸｉａｏｐｉｎｇ...     

CAD中模型库管理系统

ＣＡＤ中机械设计模型的不断扩展，特别是大型装备包含众多零部件的设计模型，为使这些模型能有序调用，模型库管理系统（ＭＢＭＳ）成为ＣＡＤ系统中的关键问题。本文介绍了ＣＡＤ中ＭＢＭＳ的目标和任务，ＭＢＭＳ应具有的功能和结构，ＭＢＭＳ中的几项关键技术以及今后的展望。     

ESTIMATING THE CUTTER＇S MAXIMUM DIAMETER IN 5－AXIS NC FACE MILLING OF TURBINE BLADES

ＥＳＴＩＭＡＴＩＮＧＴＨＥＣＵＴＴＥＲ＇ＳＭＡＸＩＭＵＭＤＩＡＭＥＴＥＲＩＮ５－ＡＸＩＳＮＣＦＡＣＥＭＩＬＬＩＮＧＯＦＴＵＲＢＩＮＥＢＬＡＤＥＳ￥ＬｉＭｉｎｇ；ＺｈｕＸｉｎｘｉｏｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｎｕｆａｃｔｕｒｉｎｇＥｎｇｉｎｅｅｒ...     

矩形板动力响应计算的迁移子结构法

矩形板动力响应计算的迁移子结构法杜国君，陈继荣（东北重型机械学院，齐齐哈尔）ＴＨＥＴＲＡＮＳＦＥＲＳＵＢＳＴＲＵＣＴＵＲＥＭＥＴＨＯＤＡＢＯＵＴＤＹＮＡＭＩＣＲＥＳＰＯＮＳＥＣＡＬＣＵＬＡＴＩＯＮＯＦＲＥＣＴＡＮＧＵＬＡＲＰＬＡＴＥＳ￥ＤｕＧｕｏ－ｊ...     

控制系统计算机辅助设计的研究进展

本文综述了控制系统计算机辅助设计ＣＡＣＳＤ的形成以及研究进展情况,介绍了控制领域具有影响的一些ＣＡＣＳＤ软件和当前ＣＡＣＳＤ的发展趋势。     

控制系统计算机辅助设计专家系统的开发

本文讨论了一个控制系统计算机辅助设计(英文缩写为 CACSD)软件包的智能用户接口——专家系统的设计.设计该专家系统的主要目的就是尽可能减少用户运行 CACSD 软件包所需的各种知识,帮助和指导他们获得满意的设计结果.本文着重阐述了第三代 CACSD 软件包(即具有专家系统支持的 CACSD软件包)的必要性和重要性,给出了第三代 CACSD 软件包的总体框图和其中专家系统的结构,并对框图和结构中各模块的功能进行了详细的讨论。我们在本文中论述的一些概念.思想和想法在第三代CACSD 软件包的开发中将具有一定的价值.     

Performance-based control system design automation via evolutionary computing

This paper develops an evolutionary algorithm (EA) based methodology for computer-aided control system design (CACSD) automation in both the time and frequency domains under performance satisfactions. The approach is automated by efficient evolution from plant step response data, bypassing the system identification or linearization stage as required by conventional designs. Intelligently guided by the evolutionary optimization, control engineers are able to obtain a near-optimal “off-the-computer” controller by feeding the developed CACSD system with plant I/O data and customer specifications without the need of a differentiable performance index. A speedup of near-linear pipelineability is also observed for the EA parallelism implemented on a network of transputers of Parsytec SuperCluster. Validation results against linear and nonlinear physical plants are convincing, with good closed-loop performance and robustness in the presence of practical constraints and perturbations.     

An efficient representation for linear constraints

An efficient representation for the linear constraints generated by a recent CACSD (computer-aided control system design) method has been developed. The linear constraints arise from engineering constraints on the time- and frequency-domain responses of the closed-loop system. The representation reduces the storage requirements and improves the efficiency of the quadratic programming algorithm used by the design method. The algorithm performs two distinct operations on the individual constraints. The first determines if a constraint has been satisfied and the second is the computation of the distance in a specified search direction     

Formalization and practical implementation of a conceptual model for PID controller tuning

This document describes the process of implementation and formalization of a rule‐based conceptual model oriented to PID tuning, developed by an expert in the domain of control engineering. The quality of the formal model is critical to carry out an implementation process oriented to get a CACSD (Computer Aided Control System Design) software application, where a non‐expert user can perform a tuning process aided by the application, and where the expert in control can update rules in the formal model to improve the tuning process, without the necessity of editing the source code of the software application. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Robust stability evaluation of sampled-data control systems with a sector nonlinearity in a gain-phase plane

This paper describes a graphical evaluation of the robust stability in a frequency domain based on the results from our previous paper in which the extension of Popov's criterion to discrete-time systems was expressed in an explicit form. The control system described herein is a sampled-data control system with one time-invariant nonlinear element (sector nonlinearity) in the forward path. For the purpose of application to a computer-aided control system design (CACSD), we will present an evaluation method of the robust stability in connection with the size of sector nonlinearity and the gain margin on a gain-phase diagram (i.e. a modified Nichols chart). We will show two results as numerical examples: one where Aizerman's conjecture was approved, and one where it was not. Copyright © 1999 John Wiley & Sons Ltd.     

On-line evolution of robust control systems: an industrial active magnetic bearing application

An electrical pump running on active magnetic bearings (AMBs) is described.To overcome the difficulty of obtaining an accurate model of the system, the control system is designed on-line. An optimiser modifies controller parameters running on the controller (a digital signal processor) in real time and the resulting sensor data is recorded and processed. On-line optimisation of the controller is achieved from within a commercial CACSD software package using H₂ and H_∞ measures of tracking as design objectives. A multiobjective genetic algorithm is used to drive the optimisation for the AMB system. The resulting controller is compared with that of a manually tuned controller and significant improvements in performance and robustness are observed.     

CAutoCSD – Evolutionary Search and Optimisation Enabled Computer Automated Control System Design

This paper attempts to set a unified scene for various linear time-invariant (LTI) control system design schemes, by transforming the existing concept of "computer-aided control system design" (CACSD) to novel "computer-automated control system design" (CAutoCSD). The first step towards this goal is to accommodate, under practical constraints, various design objectives that are desirable in both time and frequency domains. Such performance-prioritised unification is aimed at relieving practising engineers from having to select a particular control scheme and from sacrificing certain performance goals resulting from pre-commitment to such schemes. With recent progress in evolutionary computing based extra-numeric, multi-criterion search and optimisation techniques, such unification of LTI control schemes becomes feasible, analytical and practical, and the resultant designs can be creative. The techniques developed are applied to, and illustrated by, three design problems. The unified approach automatically provides an integrator for zero-steady state error in velocity control of a DC motor, and meets multiple objectives in the design of an LTI controller for a non-minimum phase plant and offers a high-performance LTI controller network for a non-linear chemical process.     

基于小波变换的无驱动结构微机械陀螺信号自旋频率的提取

针对一种新型陀螺,它能敏感旋转载体的俯仰、偏航和滚转角速度,敏感信号是一种调幅波信号,载波频率是自旋频率,包络是横向角速度。实际应用中,需要精确提取自旋频率。基于此,提出了一种提取载波频率的新的方法——小波变换构造解析函数法,对自旋频率解算算法进行了理论推导,并通过MATLAB软件对噪声比为30 dB的模拟陀螺调幅波信号进行了自旋频率的提取和误差分析,其中Hilbert变换相对误差为0.033 6,小波变换相对误差为0.017 8。对三轴精密转台实时测试的横向角速度为180°/s的陀螺信号进行了自旋频率的提取和误差分析,其中Hilbert变换相对误差为0.035 9,均方差MSE为7.915 9;小波变换相对误差为0.001 8,均方差MSE为0.293 7。小波变换较Hilbert变换求解自旋频率精度提高二十倍,降噪性能和频率稳定性更好。