Computing distance transformations in convex and non-convex domains

It is shown that the well known two-pass sequential local transformation algorithm for computing a distance transformation in rectangular domains may fail in some convex integer domains, but that a four-pass algorithm is sufficient in all two-dimensional convex domains. For non-convex domains the number of passes necessary is shown to be generally greater. Two propagation algorithms for computing the distance transformation are described and shown theoretically and experimentally to be computationally more efficient than the sequential local transformation algorithm in non-convex domains of complex shape. The relationship of the distance transformation in non-convex domains to some more general transformations is explored.     

强化技改决策促进技术进步和企业发展

以有效的技改投资决策理念指导企业技改投资，加快了企业技术进步，促进了企业跨越式发展，使三钢的产能从1996年年产钢50万t钢规模发展到目前的200万t钢水平，且优化了产业结构，技术经济指标从全国同行业的中下游上升到领先水平，增强了企业实力。但是，在取得显著成绩的同时，周边民营钢铁企业异军突起，面对严峻的挑战，三钢力争两年内依靠技改使产能达到300万t钢规模，并筹谋更远大的发展。     

Use of a neural network to link AFM etch patterns to plasma parameters

Plasmas play a critical role in depositing thin films or etching fine patterns while manufacturing integrated circuits. A new model for plasma diagnosis is presented. This was accomplished by linking atomic force microscopy (AFM) to plasma parameters using a neural network. Experimental AFM data were collected during the etching of silicon oxynitride films in C₂F₆ inductively coupled plasma. Surface roughness of etched patterns was characterized by means of discrete wavelet transformation. This led to the construction of three vertical (type I), diagonal (type II), and horizontal (type III) wavelet coefficient-based models. The performance of diagnosis models was evaluated in terms of the prediction and recognition accuracies. Both accuracies were optimized as a function of the number of hidden neurons. Comparisons revealed that the type I model yielded the largest recognition and the smallest prediction error. This was demonstrated even under stricter monitoring conditions. More improved diagnosis is expected by enhancing AFM resolution.     

Economic Model to Optimize Underground Utility Protection

The need for better protecting our vital infrastructure from being damaged or destroyed has received increased attention since the terrorist attacks on September 11, 2001. The tragedy of having thousands of innocent people die before the eyes of an entire nation awakened people to the reality of “managed” attacks of unthinkable magnitudes. However, tragedies of a smaller scale are a daily occurrence but accepted as “collateral damage” of work in an unsafe environment. This paper presents a cost-benefit analysis to address the question of how much money should be spent in protecting underground utilities from damage. During the study of an actual incident it was found that the total costs of such accidents are vastly underreported because only costs for emergency responses and repair are tallied up. This paper makes the case that a comprehensive approach for assessing the total economic impact of such incidents on the public, business, and government is the critical stepping stone to a mathematical optimization of expenditure for damage prevention. In addition, the reader will quickly realize that the use of the presented optimization model provides theoretical underpinning for the engineering profession in its effort to better protect our critical infrastructure from terrorist attacks.     

Energy efficiency, carbon emissions and economic development in Venezuela

Venezuela's vast natural resource base has largely shaped the nation's economic and energy-use patterns. Major opportunities exist for improving the efficiency of energy use in Venezuela and, consequently, restraining the growth of energy-related carbon emissions. This paper presents a detailed report of one potential development path for Venezuela and estimates the ensuing levels of energy demand and CO₂ emissions associated with pursuing this path through the year 2025. The results indicate that by adopting a development strategy that incorporates structural changes in the economy, fuel-switching measures and improved end-use efficiencies, Venezuela can introduce energy efficiency and carbon restraints as part of its economic development process.     

激光冲击诱发相变的实验研究

本对激光冲击是否可以诱发相变进行了试验研究。用功率密度为１．０６×１０＾８Ｗ／ｃｍ＾２的激光器冲击Ｔ８钢表面。实验结果表明激光冲击处理使Ｔ８钢的表面显微硬度有所提高并可以发生马氏体相变。冲击处理后材料表面硬度提高了两倍，认为相变是Ｔ８钢表面硬度提高的原因之一。     

轴端沟槽底部激光强化工艺参数优化研究

分析了选用不同激光能量密度对HT300进行表面强化处理时，材料表面呈现的四种状况；未相变硬化、相变硬化、表面微熔与表面熔凝的金相组织。根据工艺要求，选取相变硬化方法对轴端沟槽底表面进行处理。分析了工件激光处理方法并通过试验研究，寻找轴端沟槽底部激光强化工艺参数；激光功率（P）、光斑直径（D）及扫描速度（V）的优化组合。硬度测试及耐磨性能试验表明：激光相变处理和激光熔凝处理后轴端沟槽底部表面较表面感应淬火硬度分别提高7%和34%，绝对磨损体积分别下降了13%和25%。实践证实，对轴端沟槽底部激光相变硬化处理方法较其他表面处理方法工艺简单，加工工件符合技术要求，试验结果对零件表面处理提供了可靠依据。     

高炉鼓风机就地扩容改造方案及经济效益

介绍了利用高炉鼓风机基础实施不易地扩容改造的设计工艺方法，该方法不仅降低了设计、施工、安装费用，而且缩短了施工周期，降低了固定资产投资。     

提高综合勘测实力开拓岩土工程市场

随着西北勘测设计研究院（以下简称西北院）勘测总队所承担的黄河龙￣青段、白龙江流域等河段前期综合勘测工作的相继结束，拥有２０００多名职工的勘测队伍面临着何去何从的重大选择。在此转折关头，勘测总队面对现实，审时度势，抓住机遇，开拓前进，及时转轨变型，制定了本单位发展的战略和方向，使勘测总队由单一勘测业务转变为集勘测与岩土工程施工为一身的新型综合队伍。几年来，经过全体职工的奋发努力，缍获得了１９９５年￣     

A Method of Combined SHPB Technique and BP Neural Network to Study Impact Response of Materials

Abstract:  A new method combining the split Hopkinson pressure bar (SHPB) technique with the back-propagation (BP) neural network program is proposed. By this method, the treated strain wave signals become smooth with less noises induced by the transverse inertia. Moreover, the dynamic rate-dependent constitutive behaviour of materials can be identified, without any pre-assumption of a constitutive model. It is found that by taking the experimentally measured data of strain, strain rate and time as 'input' and the corresponding data of stress as 'output' of the BP neural network, the dynamic constitutive behaviour with internal damage or phase transformation evolution is easy to be identified, where the time could represent either the internal damage evolution or phase transformation process accompanied with the deformation process. It is emphasised that the data learnt by the BP neural network must include both loading and unloading processes, if the whole loading and unloading response is to be correctly predicted. The comparisons between the predictions and experimental results are in good agreement for both polyamide (PA) polymer (as an example of nonlinear viscoelastic materials) and Ti–Ni alloy (as an example of superelastic materials with stress-induced phase transformation).