A hybrid PC/PLC architecture for manufacturing-system control—theory and implementation

This paper presents a novel and generic PC/PLC-based software/hardware architecture for the control of flexible manufacturing workcells. The proposed implementation methodology is based on the utilization of any one of the available formal discrete-event-system control theories in conjunction with state-of-the-art industrial programmable-logic controllers (PLCs). The methodology has been illustrated to be a viable technique through its actual implementation in our laboratory using a robotic-workcell testbed. The specific control theory used is a combination of Extended Moore Automata and Ramadge-Wonham Automata that has been developed by our research group. The modular control software architecture has been developed for MS-Windows environments (running on one PC interfaced to the PLCs) and allows the use of different formal control theories as well as different commercial PLC hardware. The effective graphical user interface provides a transparent programming environment, where users are not expected to have a full knowledge of the formal control theory used.     

一种用于版权保护的音频数字水印算法

研究了一种基于小波变换的音频数字水印算法，水印为一幅二值图像，仿真实验表明该算法具有较强的稳健性，可用于数字音产品的版权保护。     

Stable redesign of predictive control

The paper deals with I/O versions of receding horizon controllers based on the minimization of multistep quadratic costs with the constraint that the terminal state goes to zero. The resulting control law yields stable closed-loop systems under sharp conditions. Simulation results are presented to both verify the theoretical analysis and relate the new control law with GPC     

Hiding iris data for authentication of digital images using wavelet theory

This paper introduces an efficient approach to protect the ownership by hiding an iris data into digital image for an authentication purpose. It is based on the theory of wavelets. The idea is to secretly embed biometric data (iris print) in the content of the image identifying the owner. The system is based on an empirical analysis of biometric and watermarking technologies, and it is split into several processes. The first process is based on iris image analysis, which aids the generation of the iris code (watermark); the second and the third processes deal with embedding and detecting a watermark; and the last process deals with the authentication. A new metric that measures the objective quality of the image based on the detected watermark bit is introduced, which does not require the original unmarked image for watermark detection. Simulation results show the effectiveness and efficiency of the proposed approach. The text was submitted by the author in English.     

关于离散Kirchhoff薄板单元的研究

本文对离散Kirchhoff薄板单元进行了深入的分析。文中将用于建立离散Kirchhoff单元的泛函分为三部分,分别用应变第一不变量、绕Z轴的转动偶和有关的单元边界上的积分来表达,并阐明了各部分的作用。其中单元的收敛性质完全由第一、三部分所决定,而第二部分则控制了单元的计算精度。在此基础上,文中建议了一种提高离散Kirchhoff单元精度的新方法,并由此推导了一个任意四边形离散Kirchhoff单元。计算表明,本文的改进单元与原来的离散Kirchhoff单元及其改进型相比,计算精度有了显著提高。     

Recursive solution of inverse natural convection problems by means of mode reduction

 A recursive method based on the Kalman filtering is developed to solve inverse natural convection problems of estimating the unsteady nonuniform wall heat flux from temperature measurements in the flow. By employing the Karhunen–Loève Galerkin procedure that reduces the Boussinesq equation to a small set of ordinary differential equations, the computational difficulties associated with the Kalman filtering for the partial differential equations are overcome. The present method is assessed through several numerical experiments, and is found to yield satisfactory results. Received 20 January 2001 / Accepted 31 May 2001     

建设工程质量事故与工程质量管理

针对建设工程中质量事故的严重性，分析了事故发生的原因，介绍了建设工程质量控制的管理对策，指出建设工程中的各个环节都应以安全性要求为中心，以保证工程整体质量，满足安全的要求。     

我国抽水蓄能电站发展问题探讨

抽水蓄能电站在电力系统中担负着调峰填谷、调频、调相、事故备用等重要任务，是电网经济而有效的调控手段。但以电量为唯一评价指标，其动态效益不能转化为财务效益，严重影响抽水蓄能电站的财务生存能力。建议借鉴国外经验，结合中国国情，加强对这一课题的研究，以充分发挥抽水蓄能电站的作用和效益。     

On finding optimal and near-optimal lineal spanning trees

The search for good lineal, or depth-first, spanning trees is an important aspect in the implementation of a wide assortment of graph algorithms. We consider the complexity of findingoptimal lineal spanning trees under various notions of optimality. In particular, we show that several natural problems, such as constructing a shortest or a tallest lineal tree, are NP-hard. We also address the issue of polynomial-time, near-optimization strategies for these difficult problems, showing that efficient absolute approximation algorithms cannot exist unlessP = NP.This author's research was supported in part by the Sandia University Research Program and by the National Science Foundation under Grant M IP-8603879.This author's research was supported in part by the National Science Foundation under Grants ECS-8403859 and MIP-8603879.