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81.
Some approximate solutions for predicting the stress intensity factor of a short crack penetrating an inclusion of arbitrary shape have been developed under mode I and mode II loading conditions. The derivation of the fundamental formula is based on the transformation toughening theory. The transformation strains in the inclusion are induced by the crack-tip field and remotely applied stresses, and approximately evaluated by the Eshelby equivalent inclusion theory. As validated by detailed finite element (FE) analyses, the developed solutions have good accuracy for different inclusion shape and for a wide range of modulus ratio between inclusion and matrix material.  相似文献   
82.
We propose a general modeling framework to evaluate the performance of cache consistency algorithms. In addition to the usual hit rate, we introduce the hit* rate as a consistency measure, which captures the fraction of non-stale downloads from the cache. We apply these ideas to the analysis of the fixed TTL consistency algorithm in the presence of network delays. The hit and hit* rates are evaluated when requests and updates are modeled by renewal processes. Classical results on the renewal function lead to various bounds.  相似文献   
83.
Three applications of sampling-based sensitivity analysis in conjunction with evidence theory representations for epistemic uncertainty in model inputs are described: (i) an initial exploratory analysis to assess model behavior and provide insights for additional analysis; (ii) a stepwise analysis showing the incremental effects of uncertain variables on complementary cumulative belief functions and complementary cumulative plausibility functions; and (iii) a summary analysis showing a spectrum of variance-based sensitivity analysis results that derive from probability spaces that are consistent with the evidence space under consideration.  相似文献   
84.
提出了一种考虑分布电容的故障测距新算法。该算法基于微分方程描述的线路数学模型,利用单端信息对高压输电线路进行故障测距,保留了解微分方程算法的简单可靠、现实可行、不必考虑衰减直流分量和谐波及电网频率波动影响的特点,同时考虑过渡电阻和分布电容的影响,克服了传统解微分方程法中在经高阻接地故障时测距误差过大和忽略分布电容引起的故障定位不准确的缺点。为了检验算法的精度,进行了大量的动模实验。结果表明,算法原理正确并具有较高的测距精度。  相似文献   
85.
Provides the biography of David W. Johnson and announces that he has won the Award for Distinguished Contributions of Applications of Psychology to Education and Training for programmatic research, comprehensive research reviews, and revision of theory over four decades of persistence that have provided the knowledge foundation for cooperative learning, constructive controversy, conflict resolution, and peer mediation training. A selected bibliography is also provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
86.
A model for preventive maintenance operations and forecasting   总被引:2,自引:1,他引:1  
Equipment costs constitute the greatest majority of overall costs for semiconductor manufacturing. Therefore, maintaining high equipment availability has been regarded as one of the major goals in the industry. The ability to forecast correctly equipment preventive maintenance (PM) timing requirements not only can help optimizing equipment uptime but also minimizing negative impacts on manufacturing production efficiency. This research used grey theory and evaluation diagnosis to construct a PM forecasting model for prediction of PM timing of various machines. The results showed significant improvements of PM timing predictions compared to the existing method based on experience and an alternative method proposed by Li and Chang (Semiconductor Manufacturing Technology Workshop 2002: 10–11, pp. 275–277) for the same fab cases. Received: June 2005 / Accepted: December 2005  相似文献   
87.
88.
基于湍流两相流理论建立了高炉喷煤两相流动及传质三维数学模型。采用该模型指导高炉生产 ,高炉利用系数由2 .7t/(m3.d)提高到 3 .0 t/(m3.d)以上 ,焦比由 460 kg/t降到 40 0 kg/t,煤比达到 10 0 kg/t,提高了高炉的各项经济技术指标。  相似文献   
89.
ABSTRACT Postmortem structural changes in titin and nebulin filaments were investigated by incubating isolated myofibrils in a solution containing 0.1 mM calcium ions and various concentrations of a protease inhibitor. The inhibition curves showed 2 abnormal steps with increases in the concentration of leupeptin or calpastatin domain I. While the amounts of unchanged titin and nebulin were constant in the 1st step, the 2nd occurred at higher protease inhibitor concentrations. These facts indicated that excess amounts of leupeptin and calpastatin domain I caused deterioration in titin and nebulin properties, thus interfering with the binding of calcium ions. We concluded that the severance of titin and nebulin filaments in the 1st step were induced by calcium ions at 0.1 mM.  相似文献   
90.
无源性理论在永磁同步电动机混沌控制中的应用   总被引:2,自引:0,他引:2  
永磁同步电动机在一定的工作条件下呈现出混沌运动,根据无源性网络理论,设计电动机混沌动力学模型的控制器,将混沌系统等效为无源系统,消除系统中的混沌运动,降低系统自激振动的危害,实现混沌系统的快速稳定。  相似文献   
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