系统构造技术的研究及其在CAI软件开发平台研制中的应用

本文首先比较了目前的几种系统构造技术，对它们的优缺点进行了深入的评析，然后结合我们的科研体会，重点讨论了基于对象构件的系统构造技术并给出了部分实例。本文的中心思想是基于构件的系统构造技术是未来软件系统开发的必由之路。     

喷洒有效微生物群对玉米抗旱性的影响

采用孕穗期干旱处理前喷施有效微生物群（ＥＭ）研究干旱对玉米叶片膜脂过氧化和抗性酶及产量的影响。结果表明：ＥＭ能明显降低ＭＤＡ含量，提高ＳＯＤ和ＣＡＴ活性，增强玉米的抗旱性并提高产量。     

基于反攻击的数字图像水印方法

在实际应用中 ,加有水印的数字图像不可避免会遭到一些有意或无意的攻击 .针对一些常用的攻击方法 ,提出了一种反攻击方法和相应的水印算法 ;算法自适应地选择水印嵌入位置和确定水印序列长度 ;水印嵌入在 DWT域进行 ;根据人眼视觉掩蔽特性确定水印嵌入强度 .实验结果表明该方法具有较好的图像自适应性和水印不可见性 ;对JPEG压缩、图像加噪声和图像滤波等常见的攻击方法具有极强的鲁棒性     

多总线混合分布式网络控制系统研究

测控仪表的数字化和通信技术的发展，使孤岛式的局域自动化正向网络式全局自动化转变，但现场设备接口标准和控制网络协议的多样化，从最初的通用串行通讯发展到今天的现场总线和工业以太网，导致了多总线协议在工业现场普遍并存．鉴于此。本文研究了这种多总线混合分布式网络控制系统。对其实现的关键技术进行了探讨．重点研究了底层可靠实时数据通讯和整个系统的信息集成问题．同时，对正在发展的具有Ethernet接口的新型测控设备与这种网络之间的集成问题进行了分析．本文探讨的问题，在企业提高自动化水平过程中具有普遍性，有重大的实用背景．     

首钢板坯连铸机改造工程设计及投产

介绍了首钢第二炼钢厂双流大板坯连铸机高效化改造工程项目的设计及投产情况。重点介绍了连铸机改造机型的确定、为提高生产能力和产品质量而采取的主要技术措施、工艺设备改造主要内容、改造前后铸机主要技术参数对比以及工程项目施工投产情况等。     

Modeling two-windows TCP behavior in differentiated services networks

Two important issues in assured services within differentiated services architecture are bandwidth guarantee and fair sharing of unsubscribed bandwidth among TCP flows with and without bandwidth reservations. Although the subscribed bandwidth can be guaranteed by increasing network capacity or deploying strict admission control mechanisms, the costs of such solutions are very high. The issue of fair sharing of excess bandwidth is also not well solved. To address those issues, a modified TCP, named two-windows TCP, has been proposed. The performance of the protocol is evaluated by simulations. But its effectiveness is not validated theoretically under general network conditions, which is important for understanding the benefits and costs of using the protocol. In this paper, an analytical model is developed for the purpose. The model characterizes throughput of individual two-windows TCP flow as a function of contract rate, round trip time, loss rates of In and Out packets. Extensive simulations validate the analytical model. It's shown two-windows TCP is effective not only on solving the issues of bandwidth guarantee and fair sharing of unsubscribed bandwidth, but also on increasing the utilization of bottleneck link bandwidth. Moreover, its performance is robust to network conditions, which is important for wide deployment over Internet.     

A combined backstepping and small-gain approach to robust adaptive fuzzy control for strict-feedback nonlinear systems

In this paper, a robust adaptive tracking control problem is discussed for a general class of strict-feedback uncertain nonlinear systems. The systems may possess a wide class of uncertainties referred to as unstructured uncertainties, which are not linearly parameterized and do not have any prior knowledge of the bounding functions. The Takagi-Sugeno type fuzzy logic systems are used to approximate the uncertainties. A unified and systematic procedure is employed to derive two kinds of novel robust adaptive tracking controllers by use of the input-to-state stability (ISS) and by combining the backstepping technique and generalized small gain approach. One is the robust adaptive fuzzy tracking controller (RAFTC) for the system without input gain uncertainty. The other is the robust adaptive fuzzy sliding tracking controller (RAFSTC) for the system with input gain uncertainty. Both algorithms have two advantages, those are, semi-global uniform ultimate boundedness of adaptive control system in the presence of unstructured uncertainties and the adaptive mechanism with minimal learning parameterizations. Four application examples, including a pendulum system with motor, a one-link robot, a ship roll stabilization with actuator and a single-link manipulator with flexible joint, are used to demonstrate the effectiveness and performance of proposed schemes.     

Analysis,simulation and verification of a bipolar current source power resonant inverter

A high‐frequency bipolar current source resonant inverter introduced in this paper has dramatic zero‐voltage‐switching (ZVS) characteristic. The analytic expressions of the resonant voltage and current are given. It indicates that the resonant waveform is composed of two parts, i.e. the oscillatory component and the stationary component. In special cases, the resonant waveform degenerates into the mono‐frequency component, as presents the graceful sinusoidal wave with very low total harmonic distortion (THD) value. Based on the closed‐form voltage and current, the component stresses on reactive elements are obtained. The impact of different component values and operating frequencies on ZVS feature is also discussed. It should be noted that the ZVS merit may be lost if the components are carelessly selected. The validity of the theoretical analysis has been proven with Pspice simulations and experimental results. Copyright © 2004 John Wiley Sons, Ltd.     

基于DSPs DMA和McBSP接口的信号采集

本文针对测控技术及自动化仪器仪表对实时数据采集和处理技术的发展要求,设计了基于DSP的DMA和McBSP技术的数据采集系统.文中分析了TMS320VC5409 DSP的DMA和McBSP的技术性能、接口方式和初始化编程,以及系统的设计过程.当CPU时钟频率为100MHz时,DMA单通道能达到的16位最高传输率为25M/s.实践证明该系统不仅提高了DSP的运行效率,而且有利于数字系统性能的全面提升.     

直流辉光和磁控增强放电等离子体的空间分辨发射光谱技术

光学发射光谱(OES)方法是等离子体诊断的有力工具之一,可以定量地给出等离子体的多种重要参数,如等离子体中的物种成分、粒子能态分布、激发温度、粒子相对密度等.本文介绍了一种用于电子回旋共振(ECR)微波等离子体磁控溅射靶附近的增强放电和直流辉光放电等离子体空间分辨诊断的发射光谱装置.其特点是光学收集系统的位置可以水平精细移动,因而可以对放电区域进行空间分辨发射光谱测量.作者利用这套装置对氩气的ECR微波等离子体和直流辉光放电等离子体进行诊断.在ECR微波等离子体的下游区内氩离子谱线的发射强度很弱,主要是高激发态原子的辐射.在磁共振增强放电区,离子谱线强度有所增加但仍比原子谱线弱,类似于直流辉光放电正柱区的光发射特性.