ATM网络基于队列长度阀值的传输调度

本文提出了ATM网络的一种实时传输调度和信元丢失控制的综合方案.这种方案是基于队列长度阀值而设计的,它适应于ATM网络面向连接的特性.本文给出了这种方案的随机Petri网性能模型,并给出模型分解和迭代的近似求解方法.     

Adaptive polygonization of geometrically constrained surfaces

n -dimensional space, where n>3. This definition can be used for given surfaces that are implicit or parametric. This paper presents a robust, adaptive polygonization algorithm for evaluating and visualizing geometrically constrained surfaces. Let be the constrained surface, a 2-surface in n-space, and let π() be its projection into the subspace spanned by the first three coordinates. Our polygonization algorithm computes π(). The method works directly with the n-space representation, but performs all major computations in 3-space. Techniques for triangulation, polygon decimation, and local refinement are also presented.     

Control of Discrete Fuzzy Systems: Uncertainty and Guaranteed Performance

Robust control designs for a discrete Takagi and Sugeno (T-S) fuzzy model are proposed. The T-S fuzzy model contains (possibly fast) time-varying uncertainty. First, a switching-type robust control is shown to stabilize the T-S fuzzy model asymptotically. Second, a saturation-type robust control is shown to render the T-S model practically stable. In both designs, only the bound of uncertainty is needed. The effectiveness of proposed designs is analyzed rigorously and illustrated by simulations.     

湖南有色金属工业发展战略评述

概述了湖南有色金属工业发展的基本现状和所存在的主要问题，分析了其面临的战略形势。指出湖南有色金属工业必须走产业结构总体优化、产业全面升级和大集团层面资本运营发展之路，并详细提出了相应的战略措施。     

钢铁精炼晶粒细化一步法初探

将自我研发从粉煤灰中分离提取微珠为主的新型钢铁用精炼晶粒细化复合材料，加入熔融钢铁液中，辅以惰性气体或机械搅动使之在数分钟内与钢液迅速反应，取样、铸坯、检测．精炼脱碳效果明显，晶粒细化等级提高，一步法实现了钢铁精炼脱碳、晶粒细化．在国内外尚属首次用此材料与方法试验研究．     

β brass bicrystal stress-strain relations

The stress-strain relations of three isoaxial and one nonisoaxial bicrystal whose grain boundaries are parallel to the stress axis have been studied. From one set of isoaxial bicrystals it has been possible, for a given strain, to determine the average stress in the grain boundary deformation zone from the relationship where σ _T is the applied stress, σ _b is the single crystal flow stress for the given strain, andV _gb is the volume fraction of grain boundary deformation zone. was determined from measured values of σ _T , σ _b , andV _gb . From these data and it was possible to extrapolate to the grain boundary to obtain σ _gb , the grain boundary stress. From the nonisoaxial bicrystal series containing a hard and a soft component, it was possible to determine at a given strain the stresses in each component and therefore the stress-strain relations from the relationship where and are the average stress in the hard and soft components respectively, andV _H andV _S are the corresponding volume fractions. The remaining two isoaxial bicrystal series were used to evaluate strengthening effects of bicrystal boundaries. YII-DER CHUANG, formerly Graduate Student, Department of Metallurgy and Materials Sciences, School of Engineering, New York University, Bronx, N. Y. 10453 This paper is based on a thesis submitted by Yii-der Chuang in partial fulfillment of the requirements for the Ph.D. degree in metallurgy at New York University, New York, N. Y.     

强流脉冲电子束轰击作用下的扩散模型及其数值计算

在温度场和应力场计算的基础上建立了强流脉冲电子束轰击作用下的扩散模型,并给出了数值方法及其数值解。该模型与方法同样适用于其它高能束流作用下的扩散过程。计算表明,浓度扩散流仍然是影响扩散的主要因素;而轰击超过一定次数后,扩散的作用将减弱;当边界条件为表面扩散时,扩散进行较快,这是表面涂覆加脉冲电子束后处理快速表面合金化工艺的理论基础。对实验结果和理论结果的对比分析表明,在脉冲轰击下,扩散激活能随空位浓度的增加而下降,从而加速扩散过程;在表面有熔化的情况下,则液态时的对流混合作用是主导因素。     

Development of an objective mental workload assessment tool based on Rasmussen's skill–rule–knowledge framework

It is important to monitor operators’ mental workload during the operation phase. Physiological measurement approaches could record the operator's mental data continuously, and might be less interruptive on the work activities. However, these methods often require the attachment of physical sensors, which are not unobtrusive in the physical sense. Furthermore, the individual difference makes calibrating to each individual tedious and requires trained persons to use. Often high noise-to-signal ratio data are hard to analyze. Due to these factors, physiological workload measurements are hardly widely applied in practical fields. In this study, an objective, non-intrusive and performance-based mental workload predictive model was proposed with high validity (R² = 0.51), which can be applied during the operation phrase. This model, developed based on the Rasmussen's skill–rule–knowledge framework, is comprised of two novel cognitive indices, the attention required index and uncertainty index. It can be used as the basis for establishing an early online warning system automatically. Furthermore, this model also predicts the types of error-prone tasks. This kind of information is expected to provide managers and supervisors with opportunities to intervene and improve tasks before error occurred. Finally, the predictive model proposed in this paper requires more practical application in fields to be completed.     

基于瞬态动力分析的装配式板桥铰缝损伤识别

根据铰缝在装配式板桥传递荷载的作用,通过数值计算方法模拟了装配式板桥在铰缝损伤后的瞬态动力学响应,比较分析了不同损伤程度、不同动荷载加载位置下各板跨中加速度幅值,提出利用多次冲击实验下各板加速度幅值比之差值作为铰缝损伤的评定依据的识别方法,并分析了这种方法的可行性.