On-Line Scheduling of Two-Machine Open Shops Where Jobs Arrive Over Time

We investigate the problem of on-line scheduling two-machine open shops with the objective of minimizing the makespan.Jobs arrive independently over time, and the existence of a job is not known until its arrival. In the clairvoyant on-line model, the processing requirement of every job becomes fully known at the arrival of the job, while inthe non-clairvoyant on-line model, this processing requirement is notknown until the job is processed and completed.In both models, scheduling of a job is irrevocable.We study the two-machine open shop problem for both models in the preemptive and in the non-preemptive version. For each of the four variants, we provide an algorithm that is best possible with respect to the worst-case performance. In the clairvoyant on-line model, the best worst-case performance ratios are 5/4 (preemptive) and 3/2 (non-preemptive), and in the non-clairvoyant on-line model, they are 3/2 (preemptive and non-preemptive).     

技术创新中的不确定性

本文从信息不确定性角度运用数理经济学方法,研究中国技术创新近10年发展的规律。首先构造了一个准三方模型,来探讨技术交易买卖双方关于卖方技术质量和买方企业生产开发能力的相对信息不对称对技术交易成交可能性和卖方期望收益的影响。其次,提出了技术交易隐含价格的概念,对技术市场作供需平衡分析,揭示出技术市场失效为“柠檬市场”的悲观前景。最后,探讨了科技实业创业三部曲,指出在科技实业事业社会发展阶段,国家或主管机构与件技实业的关系可作为一种主从关系问题来研究,其垓心是信号当且仅当有信息才有价值,最优利益分享规则要求充分利用可以获取的受托方行为信息,以解决激励和风险分担的双重要求。     

中国农业普查与农村统计的改善

中国实行改革开放政策以来,极大地解放和发展了农村生产力,使中国农村社会经济发生了深刻的历史性变化,农村统计也不断面临着挑战,急需改革和完善。１９９７年首次中国农业普查的成功,为进一步改善中国农村统计工作提供了一个良好的机遇。一、传统农村统计的形成和现...     

中国摩托车行业’98分析报告

中国摩托车行业自５０年代初开始迈步,经过２０年（６０、７０年代）的摸索、１０年（１９８０—１９９０年）的进步、５年（１９９１—１９９５年）的快速发展,开始走向成熟。１９９６、１９９７年产量增幅放慢,分别比上年增长１８．５７％与７．９６％,较之“八五”...     

资源环境价值货币化核算的理论分析

如何将资源环境因素纳入国民经济核算体系,正确地评估发展的“真谛”,实现“持续发展”目标导向下绿色国民经济核算体系是当今人类社会发展进程中一个重要命题,亦是当前世界各国及学术领域普遍关注的焦点问题。８０年代以来,欧美等国和国际组织开展了相关研究。在资源...     

Assessing Effects on Long-term Survival after Early Termination of Randomized Trials

In this paper we present an approach to using historical control data to augment information from a randomized controlled clinical trial, when it is not possible to continue the control regimen to obtain the most reliable and valid assessment of long term treatment effects. Using an adjustment procedure to the historical control data, we investigate a method of estimating the long term survival function for the clinical trial control group and for evaluating the long term treatment effect. The suggested method is simple to interpret, and particularly motivated in clinical trial settings when ethical considerations preclude the long term follow-up of placebo controls. A simulation study reveals that the bias in parameter estimates that arises in the setting of group sequential monitoring will be attenuated when long term historical control information is used in the proposed manner. Data from the first and second National Wilms' Tumor studies are used to illustrate the method.     

Beta-Bernstein Smoothing for Regression Curves with Compact Support

ABSTRACT. The problem of boundary bias is associated with kernel estimation for regression curves with compact support. This paper proposes a simple and uni(r)ed approach for remedying boundary bias in non-parametric regression, without dividing the compact support into interior and boundary areas and without applying explicitly different smoothing treatments separately. The approach uses the beta family of density functions as kernels. The shapes of the kernels vary according to the position where the curve estimate is made. Theyare symmetric at the middle of the support interval, and become more and more asymmetric nearer the boundary points. The kernels never put any weight outside the data support interval, and thus avoid boundary bias. The method is a generalization of classical Bernstein polynomials, one of the earliest methods of statistical smoothing. The proposed estimator has optimal mean integrated squared error at an order of magnitude n ^−4/5, equivalent to that of standard kernel estimators when the curve has an unbounded support.     

离心式叶轮机任意旋成面栅后区长度处理

文章揭示了叶轮栅后区长度L_3太长时,会使栅后区出气角β_2无法选择而造成无解的事实;表明在β_2变化的适当范围内,叶型后缘两侧速度差△Λ与β_2之间呈线性关系,而且该线性变化范围随L_3的增长而缩小;获得了随L_3作线性变化的规律。文章最后提出了离心式叶轮机任意旋成面叶栅流场的简单求解方法。     

英语俚语汉译初探

英语俚语难以辨认和理解,因而在翻译中其意义和风格难以得以充分传达。为了保证其意义和风格在译文中充分再现,译者必须准确理解原文,再现原文特色以及说话者的个性     

一类有理分式的积分

本文介绍了一类有理分式的积分,并得到了一组织分公式。