Web缓存优化模型研究

缓存模型研究的核心是替换策略的优化。分析并比较传统缓存模型IRM和MRM的思想,基于相对流行度以及字节代价的概念,提出满足命中率、字节命中率和延迟时间等不同性能指标要求的Web缓存优化模型,并给出相应算法。实验及分析表明,Web缓存优化模型替换算法的性能表现较传统算法有所提高。     

智能低压配变监测与无功率补偿箱设计探索

针对现有的配变监测与无功补偿箱使用中存在的诸多问题,通过在结构上找原因,从性能上找差距的方式,进行了多层面的分析、对比和研究,提出了智能化、模块化的全新设计理念,科学地实现了低压配电监测与智能无功补偿装置的有机组织。     

离散变结构控制系统的广义变速趋近律

为了研究离散变速趋近律的稳定参数区域,依据离散变速趋近律滑模的特点,得出了离散变速趋近律渐近稳定的充分条件,依照此条件获得了变速趋近律各个参数的具体范围,进而提出了广义离散变速趋近律的概念,同时也给出了其保证系统稳定的参数范围,设计了两个离散系统的广义变速趋近律的控制方案。仿真结果表明,得出的参数范围能保证系统渐近稳定。     

The Pay As You Save program in rural Arkansas: An opportunity for rural distribution cooperative profits

This case study highlights the success of the Ouachita Electric Cooperative’s Pay As You Save program in Camden, Ark., in bringing both electricity bill savings to customers and benefits to implementing utilities, especially in rural areas. It is not specifically a low-income energy assistance program, but does benefit customers with high energy burdens. Through its on-bill tariff design, PAYS overcomes many barriers, such as the split incentive challenge and the need for upfront outlays.     

混凝土结构钢筋脱钝的随机可靠度分析

根据混凝土临界氯离子浓度和氯离子扩散系数与水灰比、环境温度等的关系式,计算出不同条件下受氯盐侵蚀混凝土结构50年内钢筋表面的氯离子浓度。在分析钢筋混凝土结构钢筋表面氯离子浓度随服役年限关系的基础上,用Monte Carlo方法对钢筋脱钝的随机可靠度进行分析。对保护层厚度、水灰比和环境温度等随机变量对海工混凝土结构钢筋脱钝概率的影响进行探讨。     

Cutter mark cross method for improvement of contact stiffness by controlling distribution of real contact area

Contact surfaces do not make contact perfectly because such surfaces have a lot of asperities. The real contact area is much smaller than the nominal contact area, and the real contact areas has a non-uniform distribution because of the waviness in the contact surface. The contact stiffness is influenced not only by the deformation of the asperities, but also by the distribution of the real contact areas. In general, a contact surface with a uniform distribution of the real contact areas has greater contact stiffness. However, this requires a grinding finish and costs more than the cutting finish. In this study, a method for uniformly distributing the real contact areas easily, is proposed to improve the contact stiffness of a contact surface finished by cutting. The method is called the cutter mark cross (CMC) method. The allowable waviness in the CMC method is shown. In addition, the effect of the CMC method is investigated by experimentation. The results show that the real contact areas can be distributed uniformly using the CMC method. The horizontal and vertical contact stiffness can also be improved.     

High Temperature Oxidation of FGH96 P/M Superalloy

High temperature oxidation behaviors of FGH96 P/M superalloy have been studied in air at temperatures ranging from 600 to 1000℃. By means of isothermal oxidation testing,X-ray diffraction,SEM(scanning electron microscopy),and EDS(energy dispersive X-ray spectroscopy) analyses,the oxidation kinetics as well as the composition and morphology of scales were investigated. Thermodynamic calculations were used to explain the oxidation mechanism. The results showed that as the oxidation temperature increased,the oxidation rate,the scale thickness,and scale spallation increased. FGH96 P/M superalloy exhibits good oxidation resistance at temperature below 800℃. The oxidation kinetics follows an approximately parabolic rate law,and the oxide layer was mainly composed of Cr2O3,TiO2,and a little amount of NiCr2O4. The oxidation is controlled by the transmission of chromium,titanium,and oxygen through the oxide scale.     

航空制导炸弹制导控制律设计

根据命中精度和射程的要求,设计了某型制导炸弹的方案弹道。在滑翔段采用给定俯仰角飞行的方法,以降低马赫数,使炸弹尽快脱离跨音速飞行状态;在俯冲段采用比例导引法,导引炸弹命中目标。给出了俯仰、偏航和滚转三通道控制律,提出了控制参数的选择方法。仿真结果表明：所设计的弹道具有射程远、精度高、易实现的特点,具有较高的实用价值。     

THE MINIMUM ENTROPY PRINCIPLE IS NOT THE PRINCIPLE OF MINIMUM CROSS-ENTROPY

In this current paper the following problems are addressed: (1) extending the knowledge of a partially known probability distribution function to any point of a continuous sample space, (2) constructing an imprecise probability distribution based on the knowledge of a set of credible or confidence intervals, and (3) computing the lower and upper expected values of a random continuous variable. An example is provided.     

交流电机绕组分布系数推导方法的研究

对交流电机绕组分布系数推导的代数法进行了详尽描述,并对代数法与几何法进行了比较。