PLC在钢坯温度自动监控系统中的应用

提出了一种以PC＋PLC结构组成的钢坯温度自动监控系统,并对该系统的构成、功能作了介绍。较详细地讨论了系统中PLC的程序设计,包括对AD模块的编程技术;给出了相应的PLC梯形图程序。     

图像集的离散度矩阵及其在人脸图像识别中的应用

本文提出了图像集离散度矩阵的基本概念及用于人脸图像识别的方法。该方法把同一类图像集中的各幅图像的信息矩阵的奇异值向量作为矩阵中的一列构成图像集特征矩阵。把这些矩阵组成一图像库,并找出图像集离散度矩阵和图像库离散度矩阵,从而计算出它们的最佳投影系数。然后,把测试样本的图像集特征矩阵与图像集库中的训练样本图像集的特征按投影系数相比较找出它的相似程度,从而进行人脸图像识别。     

过程建模的Petri网模型

工作流管理的问题由于广泛存在于计算机应用的许多方面而迅速得到发展。本文介绍了一个以扩展的Petri网作为建模工具、以消息队列作为执行机制实现的过程管理的原型系统。该模型描述了活动的并发执行和依赖关系、活动激发的条件、事件顺序及文档管理等信息。执行该模型,在分布、异构、自治的环境中可自动监视、管理和调度工作任务,为业务过程重组、业务过程自动化提供了有力的支持。     

MPEG-7及其应用

MPEG－7是国际MPEG组织正在制订定的第4个MPEG标准,旨在实现多媒体内容描述的标准化。简要介绍了MPEG－7的应用背景、目标、内容及常用术语,并探讨了MPEG－7可能的应用领域。     

Dynamic view selection for time-varying volumes

Animation is an effective way to show how time-varying phenomena evolve over time. A key issue of generating a good animation is to select ideal views through which the user can perceive the maximum amount of information from the time-varying dataset. In this paper, we first propose an improved view selection method for static data. The method measures the quality of a static view by analyzing the opacity, color and curvature distributions of the corresponding volume rendering images from the given view. Our view selection metric prefers an even opacity distribution with a larger projection area, a larger area of salient features' colors with an even distribution among the salient features, and more perceived curvatures. We use this static view selection method and a dynamic programming approach to select time-varying views. The time-varying view selection maximizes the information perceived from the time-varying dataset based on the constraints that the time-varying view should show smooth changes of direction and near-constant speed. We also introduce a method that allows the user to generate a smooth transition between any two views in a given time step, with the perceived information maximized as well. By combining the static and dynamic view selection methods, the users are able to generate a time-varying view that shows the maximum amount of information from a time-varying data set.     

一个支持OO协同式设计的CASE工具

这篇文件介绍一个计算机辅助协同面向对象设计系统的设计与实现技术。文中所述的系统全面支持ＯＯＤ辅助设计,它实现了对象式系统中的要素表示及可视化设计,并支持多用户的协同开发。     

Pseudoelastic behavior in Y1−xPrxBa2Cu3Oy compounds

Tensile tests show that ferroelastic loops always occur at 100–150 K, 200–250 K and room temperature in the Y_1–xPr_xBa₂Cu₃O_y samples withx=0 and 0.1 for whichT _c is 92 K and 82.5 K respectively, and the shape memory effect is always observed in the compact sample near 130 K, just similar to that of thermal elastic martensitic alloys. The loss fraction (W/W) which is proportional to the area of ferroelastic loop as a function of temperature shows that there always exist static hysteresis (W/W) peaks at 130 K and 110 K which are attributed to the phaselike transition (PLT) characterized by the jump of lattice parameters. No ferroelastic loops and shape memory effect are observed in the range of 100 K to 150 K for the lowerT _c samples withx=0.3, 0.4 and 0.6.     

NEW TUNING METHOD FOR PID CONTROL OF A PLANT WITH UNDER‐DAMPED RESPONSE

In this paper, a tuning formula is derived for PID control of plants with under‐damped step responses. The under‐damped systems are modeled by second‐order plus dead time transfer functions. To derive the tuning rule, the dominant pole assignment method was applied to design the PID controllers for a variety of plant models. Then, the correlation between the controller parameters and the parameters of the models was found and the tuning formula derived. Several simulation examples are given to demonstrate the effectiveness and robustness of this formula.     

国内外高性能水泥浆体自收缩研究近况

综述了高性能水泥浆体自收缩机理、影响因素及减少自收缩的途径,略述了目前国内外研究现状。