现代电子工业Cpk评价中的特殊问题

现代电子工业生产具有许多新的特点，如果不针对具体情况，均采用传统工业生产中广泛使用的常规方法计算其工序能力指数，评价生产工艺水平，将可能导致错误的结论。总结了电子工业生产中工艺参数的典型特点，并讨论了工序能力指数的正确计算方法。     

掺气减蚀保护作用的新概念

利用针式掺气流速仪测量原型和模型掺气浓度场、流速场，气泡尺寸及其概率分布的研究成果表明，原型水流韦伯数高，形成微小气泡的能力比模型强，气泡上浮慢，接近底部的小尺寸气泡概率及掺气浓度比模型大。初步研究认为：0.2mm或0.5mm以下的微小气泡在掺气减蚀中起着主要作用，可能只要很小掺气浓度即可达到掺气减蚀的效果。因此以小尺寸气泡的掺气浓度，作为判断掺气减蚀保护作用的指标将更为准确。     

Modeling of Material Deformation Kinetics in the Prefracture Zone

Based on the concept of complete stress–strain diagrams, we propose a new model describing the law of stress distribution in the prefracture zone in plastic materials in view of the type of the stressed state.     

Analysis of spontaneous electrochemical oscillations by energy distribution technique

Analysis of non-stationary electrochemical oscillations emerges utilization of the techniques allowing an observation of time evolution of their parameters such as instantaneous frequency, amplitude or frequency band. An algorithm of extraction of these parameters can be based on one of linear or quadratic time-frequency representations of oscillations record. In this paper, the authors present representatives of such transformations (Choi-Williams and Cone-shaped) originating from one of the most popular joint time-frequency energy distribution—Wigner-Ville distribution. Short introduction to the mathematics of the topic discussed is provided, then the authors present an example of application in the analysis of current oscillations of copper dissolution process.     

高压对气井套管接头螺纹接触应力的影响研究

高温高压气井对螺纹密封性的要求要比油井更为严格。对于高压气井中的整个管柱,每一段处于不同的力学环境中,发生泄漏的可能性也不同,因此研究压力对气井套管接头螺纹接触应力的影响,对高压气井套管的合理使用尤为重要。利用弹塑性有限元分析方法,建立了API偏梯型螺纹套管接头的有限元模型,分析了气井压力对套管接头接触应力的影响,提供了研究压力对套管接头螺纹接触应力影响的方法。对于井口压力或井底压力超过34MPa的高压气井,应选用气密性良好的特殊螺纹接头,建议采用金属对金属的螺纹接头套管,以加强螺纹部位的连接强度和密封性能。     

Characterization of the Residence Time Distribution in Spray Dryers

In this work it is presented a study on the residence time distribution (RTD) of particles in a co-current pilot-plant spray dryer operated with a rotary atomization system. A nuclear technique is applied to investigate the RTD responses of spray dryers. The methodology is based on the injection of a radioisotope tracer in the feed stream followed by the monitoring of its concentration at the outlet stream. The experiments were performed during the drying of aqueous suspensions of gadolinium oxide. The RTD responses obtained experimentally presented good reproducibility, indicating that the technique applied is well suited to investigating fluid-dynamics of spray dryers. In addition to the experimental investigation, a mathematical model was used to describe the RTD experimental curves.     

Sociotechnical systems, risk management, and public health: comparing the North Battleford and Walkerton outbreaks

Accidents in different complex sociotechnical systems are rarely compared using the same theoretical framework for risk management. We conducted a comparative analysis of two Canadian public health disasters involving drinking water distribution systems, the North Battleford Cryptosporidium parvum outbreak in April 2001 and the Walkerton E. coli outbreak in May 2000. Both accidents resulted from a complex interaction between all levels of a complex sociotechnical system. However, the low-level physical and individual factors differed in the two cases, whereas, the high-level governmental and regulatory factors tended to be the same. These findings may have implications for the design of public policies to minimize risk in complex sociotechnical systems.     

覆盖层厚度对巷道周围应力分布的影响及巷道间相互作用的仿真

给出了覆盖层厚度对巷道周围应力分布的影响及巷道间相互作用的计算机仿真，用三维有限元法分析了在不同覆盖层厚度下巷道周围的应力分布和两个巷道之间不同距离下的相互作用。数值模拟表明了巷道周围应力分布和应力集中系数随覆盖层厚度增加的变化规律，找到了两巷道之间的距离的临界值，当两巷道间距离大于该临界值时，它们之间的相互作用消失。     

NSA-500-1型氩弧焊机VD9不同接法对引弧和稳弧的影响

从一起NSA－500－1型氩弧焊机故障，分析其高压脉冲旁路二极管VD9不同接法对引弧、稳弧及设备安全的影响。     

THE STATISTICAL DISTRIBUTION OF EXTREME VALUES OF WAVE-CURRENT FORCES ACTING ON SLENDER CIRCULAR CYLINDER IN IRREGULAR WAVES

Based on model test,the statistical distribution of extreme values of wave-current in-line forces acting on vertical circular cylinder is analyzed in this paper.It is shownthat the results calculated by the simplified method,proposed by authors,agree well with the testdata;Weibull distribution is also adoptable in the region of high KC number, and the shapeparameter a and scale parameter β are related well with KC number respectively.