改进的对称分布期望估计量的性质

本文证明了改进后的对称分布期望估计量W_p在一定条件下具有无偏性和强相合性,并给出了方差的上界,其中:W_p.=1/n-2[np] sum from a-[ap] to i=[ap]+1 X_(j),0≤p<1/2     

关于双条件期望的几乎处处收敛性

引进了B值随机变量及可测集Γ的双条件期望的概念,对双条件期望的几乎处处收敛性给出一个较为一般的定理,使原来的结果更为简洁,使用起来更方便.     

2014年我国生猪生产形势分析及2015年走势研判

对于生猪养殖户来说,2014年是困难重重和极具考验的一年。猪价任性,不按常理出牌,旺季不旺,淡季反升,养殖亏损程度之深历史罕见。本轮猪周期规律反常,最根本的原因是生猪出栏量整体处于高位,市场长期处在供大于求的状态。而随着居民肉食品消费多元化,对猪肉制品需求量也在逐年减少,供大于求的局面早在2011年底就已形成。2013年夏季南方洪灾导致生猪价格上涨,很多养猪户却将这次涨价当作新一轮周期上涨阶段的开始,盲目扩大规模导致生猪供大于求的局面进一步扩大。而2014年下半年能繁母猪存栏量持续下降,将直接影响到2015年生猪出栏量,在需求不变的情况下,供应量减少势必造成价格上涨。     

湖南水电今后的发展和特点

本文介绍了湖南水电概况、发展过程及今后展望,论述按综合利用原则规划,水资源开带来的效益,及在１９９８年特大洪水发生后取得的成绩。说明水资源开发应轵快步伐。湖南水电已初具规模,不仅为省网提供了大量的电力,也为防洪、治水、减灾和经济发展作了贡献,今后要健全防洪系统,兴建必要的水库,发展水电。     

美国太阳能工业的发展与中国太阳能工业的展望

世界将日益依赖于清洁、高效和可持续的能源,因此,太阳能工业将以史无前例的速度发展,文章概述了美国太阳能工业的特点及其发展现状并对可供中国原子能工业借鉴的美国经验和信息作了归纳性的阐述。     

ROBUSTNESS OPTIMIZATION FOR CONSTRAINED NONLINEAR PROGRAMMING PROBLEMS∗

In realistic situations engineering designs should take into consideration random aberrations from the stipulated design variables arising from manufacturing variability. Moreover, many environmental parameters are often stochastic in nature. Traditional nonlinear optimization attempts to find a deterministic optimum of a cost function and does not take into account the effect of these random variations on the objective. This paper attempts to devise a technique for finding optima of constrained nonlinear functions that are robust with respect to such variations. The expectation of the function over a domain of aberrations in the parameters is taken as a measure of ‘robustness’ of the function value at a point. It is pointed out that robustness optimization is ideally an attempt to trade off between ‘optimality’ and ‘robustness’. A newly-developed multi-criteria optimization technique known as Normal-Boundary Intersection is used to find evenly-spaced points on the Pareto curve for the ‘optimality’ and ‘robustness’ criteria. This Pareto curve enables the user to make the trade-off decision explicitly, free of arbitrary ‘weighting’ parameters.

This paper also formulates a derivative-based approximation for evaluating the expected value of the objective function on the nonlinear manifold defined by the state equations for the system. Existing procedures for evaluating the expectation usually involve numerical integration techniques requiring many solutions of the state equations for one evaluation of the expectation. The procedure presented here bypasses the need for multiple solutions of the state equations and hence provides a cheaper and more easily optimizable approximation to the expectation. Finally, this paper discusses how nonlinear inequality constraints should be treated in the presence of random parameters in the design. Computational results are presented for finding a robust optimum of a nonlinear structural optimization problem.     

解舒率的分布及其特征数

本文利用一粒茧的中途落绪数服从卜里耶·埃肯别尔根(Polya Eggenbergen)分布的结论,直接从解舒率的定义出发导出了解舒率的理论分布,求出其期望和方差的表达式,并证明了当n→∞时解舒率渐近地服从正态分布N(1/(1 λ),λ(1 ρ)/(n(1 λ)~4)))。最后对理论结果进行了随机模拟和检验,并讨论了分布参数的变化对解舒率的方差的影响,还讨论了应用中的一些问题。     

某舰炮弹头飞行过程的可靠性评价

要评价舰炮系统的可靠性,就要做各种可靠性试验和复杂计算,这对造价昂贵而又复杂的舰炮要付出较高的代价。因此,需要找出一种准确、实用,而试验和计算又尽可能简单的方法。本文利用弹头飞离炮口后,飞行弹头成功率的数学期望来评价弹头飞行过程的可靠度,以此来作为评价舰炮可靠性的一种方法。     

超硬材料及制品现状与展望

作者欲通过了解的基本情况,分析行业总体形势,掌握行业发展动态,为企业经营者的决策提供参考依据。文章介绍了超硬材料单晶、复合片、细料、微米级（含纳米级）料等设备及产品的行业最新情况,并提供了产量和质量的数据。还简述了金刚石工具已形成的两个方向,并列举了部分石材精加工用的金刚石工具及其发展。