排除系统启动时"自动运行"程序的干扰

在校园网信息端点设备的维护中，常有用户抱怨，他们的机器一打开就“自动运行”一些乱七八槽的网页，并且有的根本无法关闭，给用户正常使用设备造成了一定的干扰。本文将全面分析这类干扰用户的程序并给出相应的解决办法，供广大校园网用户参考。     

谈谈多媒体网络教学的特性

本文通过对多媒体特性的论述 ,提出了多媒体网络教学中学生的主体性和教师的主导性在多媒体网络教学中的新角色定位     

The Luxembourg Wealth Study – A cross-country comparable database for household wealth research

The paper describes the Luxembourg Wealth Study (LWS), an international project launched in 2003 by the Luxembourg Income Study and by institutions from Canada, Cyprus, Finland, Germany, Italy, Norway, Sweden, the United Kingdom, and the United States. The aim of the project is to assemble and to harmonise existing micro-data on household wealth, in order to provide a sounder basis for comparative research on household net worth, portfolio composition, and wealth distributions.Eva Sierminska is the LWS project co-ordinator, Andrea Brandolini and Timothy Smeeding are the LWS project leaders. Further information on the LWS project is available at .     

我国黄金期货价格波动率预测研究：来自模型缩减方法的新证据

黄金作为重要的避险资产,对其价格波动的定量描述和预测对于各类投资者的风险管理决策意义重大。基于标准回归预测模型,采用主成分分析、组合预测和两种主流的模型缩减方法(Elastic net 和Lasso)构建新的波动率预测模型,探究哪种方法能够更有效地利用多个预测因子信息。进一步,运用模型信度集合(model confidence set,MCS)、样本外R2和方向测试(Direction-of-Change,DoC)三种评价方法检验新模型的样本外预测精度。实证结果显示：不论是基于哪一种评价方法,相比其它竞争模型,两种缩减模型的样本外预测精度均为最优,可以为我国黄金期货价格的波动率预测提供可靠保障。     

考虑成本和收益净现值的确定性存储决策模型研究

净现值是企业决策中需要考虑的重要宏观经济因素.本文建立了考虑成本和收益净现值的连续时间有限时段确定性库存系统的最优存储和定价决策模型,证明了给定价格下最优策略中任意两个相邻订货周期之间的递推关系,分析了该关系的解析性质,并得出订货周期长度的上下限.在此基础上提出求解最优存储策略和最优价格的两步优化算法.最后通过数值算例对本文模型及结果做出说明.     

网络文化的冷思考

网络文化作为网络时代产生的新兴文化范式,以其交互、共享、虚拟现实性等特点迎合了信息时代快节奏的工作方式和生活方式,给人们的工作和生活带来了极大的方便,还对传统文化带来了深刻的影响,但同时也为社会环境、文化建设带来了诸多不容忽视的负面影响。     

The Relationship Between Private Safety Nets and Economic Outcomes Among Single Mothers

This article examines the relationship between private safety nets and economic outcomes among 2,818 low‐income single mothers in three U.S. counties in the 1990s. I define private safety nets as the potential to draw upon family and friends for material or emotional support if needed. Using a combination of survey and administrative records data collected for the National Evaluation of Welfare‐to‐Work Strategies, I find that human capital deficits, depressive symptoms, and low self‐efficacy are associated with having less private safety net support, suggesting that social network disadvantages compound individual‐level disadvantages. I also find that mothers with strong private safety nets worked more, earned more, and were less reliant on welfare compared with mothers with more meager private safety nets.     

Reliability Analysis Based on the Losses from Failures

The conventional reliability analysis is based on the premise that increasing the reliability of a system will decrease the losses from failures. On the basis of counterexamples, it is demonstrated that this is valid only if all failures are associated with the same losses. In case of failures associated with different losses, a system with larger reliability is not necessarily characterized by smaller losses from failures. Consequently, a theoretical framework and models are proposed for a reliability analysis, linking reliability and the losses from failures. Equations related to the distributions of the potential losses from failure have been derived. It is argued that the classical risk equation only estimates the average value of the potential losses from failure and does not provide insight into the variability associated with the potential losses. Equations have also been derived for determining the potential and the expected losses from failures for nonrepairable and repairable systems with components arranged in series, with arbitrary life distributions. The equations are also valid for systems/components with multiple mutually exclusive failure modes. The expected losses given failure is a linear combination of the expected losses from failure associated with the separate failure modes scaled by the conditional probabilities with which the failure modes initiate failure. On this basis, an efficient method for simplifying complex reliability block diagrams has been developed. Branches of components arranged in series whose failures are mutually exclusive can be reduced to single components with equivalent hazard rate, downtime, and expected costs associated with intervention and repair. A model for estimating the expected losses from early-life failures has also been developed. For a specified time interval, the expected losses from early-life failures are a sum of the products of the expected number of failures in the specified time intervals covering the early-life failures region and the expected losses given failure characterizing the corresponding time intervals. For complex systems whose components are not logically arranged in series, discrete simulation algorithms and software have been created for determining the losses from failures in terms of expected lost production time, cost of intervention, and cost of replacement. Different system topologies are assessed to determine the effect of modifications of the system topology on the expected losses from failures. It is argued that the reliability allocation in a production system should be done to maximize the profit/value associated with the system. Consequently, a method for setting reliability requirements and reliability allocation maximizing the profit by minimizing the total cost has been developed. Reliability allocation that maximizes the profit in case of a system consisting of blocks arranged in series is achieved by determining for each block individually the reliabilities of the components in the block that minimize the sum of the capital, operation costs, and the expected losses from failures. A Monte Carlo simulation based net present value (NPV) cash-flow model has also been proposed, which has significant advantages to cash-flow models based on the expected value of the losses from failures per time interval. Unlike these models, the proposed model has the capability to reveal the variation of the NPV due to different number of failures occurring during a specified time interval (e.g., during one year). The model also permits tracking the impact of the distribution pattern of failure occurrences and the time dependence of the losses from failures.     

网收敛的非标准特征在微积分中的应用

在非标准分析的扩大模型下,利用网收敛的非标准特征来刻画微积分中数列、函数的极限以及定积分的定义,并给出了若干结论及其证明。     

社会对建立保障制度的双重要求

我国社会保障制度严重滞后,建构完善的社会保障制度是体制改革成功的重要保证。本文从西方各国历史中社会保障制度的得失出发,探讨了社会对安全网的客观要求和社会保障可能导致的社会风险;在分析各国保障模式的基础上,提出我国建立社会保障制度的模式目标。