Interactive analysis of high-dimensional association structures with graphical models

Graphical chain models are a powerful tool for analyzing multivariate data. Their practical use may still be cumbersome in some respects, since fitting the model requires a lengthy selection strategy based on the calculation of an enormous number of different regressions. In this paper, we present a computer system especially designed for the calculation of graphical chain models, which will not only automatically carry out the model search but also visualize the corresponding graph at each stage of the model fit. In addition, it allows the user to modify the graph and to fit the model interactively.     

Efficiency aggregation with enhanced Russell measures in data envelopment analysis

In aggregation for data envelopment analysis (DEA), a jointly determined aggregate measure of output and input efficiency is desired that is consistent with the individual decision making unit measures. An impasse has been reached in the current state of the literature, however, where only separate measures of input and output efficiency have resulted from attempts to aggregate technical efficiency with the radial measure models commonly employed in DEA. The latter measures are “incomplete” in that they omit the non-zero input and output slacks, and thus fail to account for all inefficiencies that the model can identify. The Russell measure eliminates the latter deficiency but is difficult to solve in standard formulations. A new approach has become available, however, which utilizes a ratio measure in place of the standard formulations. Referred to as an enhanced Russell graph measure (ERM), the resulting model is in the form of a fractional program. Hence, it can be transformed into an ordinary linear programming structure that can generate an optimal solution for the corresponding ERM model. As shown in this paper, an aggregate ERM can then be formed with all the properties considered to be desirable in an aggregate measure—including jointly determined input and output efficiency measures that represent separate estimates of input and output efficiency. Much of this paper is concerned with technical efficiency in both individual and system-wide efficiency measures. Weighting systems are introduced that extend to efficiency-based measures of cost, revenue, and profit, as well as derivatives such as rates of return over cost. The penultimate section shows how the solution to one model also generates optimal solutions to models with other objectives that include rates of return over cost and total profit. This is accomplished in the form of efficiency-adjusted versions of these commonly used measures of performance.     

电力变压器抽检质量问题分析及管控措施分析

电力变压器是电网系统中重要的配件,其质量直接关系到电力系统运行的安全性能。文章就电力变压器的抽检方法做出了简要的分析,并以此为例,对电网电力系统的35 k V电力变压器进行了质量抽检,详细分析了抽检情况,立足于用户,提出了几点加强变压器质量管理的举措。     

国外乡村建设的路径分析及启示

很多发达的资本主义国家和地区也曾有过乡村建设的历史。立足国情,它们各自采取了不同的反哺切入点、发展路径和战略模式。其中,政府的巨大推动作用、民众的广泛参与、体制的保障与革新以及中介组织的培育等在各国的乡村建设中都发挥了关键性作用。借鉴国外乡村建设经验,提出当前我国的新农村建设应赋予农村领导机构以明确主权、开展以县域单元为核心的乡村系统研究、最大化地发挥农民主体性作用。     

Implementation with partial verification

This paper examines the implementability of social choice functions when only partial verification of private information is possible. Green and Laffont (1986) used this framework to derive a necessary and sufficient condition for the revelation principle to continue to hold with partial verification. We provide economically interesting characterizations of this condition, which suggest that it may be too restrictive. This leads us to consider implementation (not necessarily truthful) in general, when there is partial verification. We consider the case where compensatory transfers are allowed, giving the mechanism designer further leeway. We show how partial verification may allow efficient implementation of bilateral trade, where it would otherwise not be possible. Received: 1 August 1998 / Accepted: 5 September 2000     

扣件式钢管高支模坍塌事故分析及防范措施

文章通过云南省近些年高支模坍塌典型事故案例的介绍,从管理和技术的角度对其进行了分析,总结了扣件式钢管高支模失稳坍塌的原因,并提出了防范措施。     

The effects of sampling on measures of association between variables based on sample means

Many studies that involve people's perceptions or behaviors focus on aggregate rather than individual responses. For example, variables describing public perceptions for some set of events may be represented as mean scores for each event. Event mean scores then become the unit of analysis for each variable. The variance of these mean scores for a variable is not only a function of the variation among the events themselves, but is also due to the variation among respondents and their possible responses. This is also the case for the covariances between variables based on event mean scores. In many contexts the variance and covariance components attributable to the sampling of respondents and their responses may be large; these components can be described as measurement error. In this paper we show how to estimate variances and covariances of aggregate variables that are free of these sources of measurement error. We also present a measure of reliability for the event means and examine the effect of the number of respondents on these spurious components. To illustrate how these estimates are computed, forty-two respondents were asked to rate forty events on seven risk perception variables. Computing the variances and covariances for these variables based on event means resulted in relatively large components attributable to measurement error. A demonstration is given of how this error is removed and the resulting effect on our estimates.     

A comparative analysis of measures of social homogeneity

Social homogeneity refers to the degree to which the preferences of individuals in a society tend to be alike. A number of studies have been conducted to determine whether or not a relationship exists between various measures of social homogeneity and the probability that a Condorcet winner exists. In this study, it is shown that a strong general relationship of this type does not exist for measures of social homogeneity which account only for the proportions of individuals with various preference rankings. That is, for measures which account for these proportions but not for the preference rankings to which they are assigned. Profile specific measures of homogeneity do account for the preference rankings to which the proportions of voters are assigned. A much stronger relationship exists between profile specific measures of homogeneity and the probability that a Condorcet winner exists than for non-profile specific measures. In particular, Kendall's Coefficient of Condordance is shown to dominate twenty other measures of social homogeneity in terms of the strength of its relationship to the probability that a Condorcet winner exists.     

全地形车后轴断裂分析与改进措施

文章通过对江苏林海集团全地形车断裂的后轴进行了分析,指出了后轴断裂的原因,并给出改进措施。结果表明,采取了改进措施后,后轴断裂事件再未发生。     

地下商场的火灾危险性分析与预防对策

对地下商场的火灾危险性进行了分析,为使地下商场安全运营,提出了预防地下商场火灾的基本措施及相应对策。     

Interregional trade and economic integration: A partial equilibrium analysis

The classical comparative static analysis of economic integration is extended to a spatial world by the theory of partial spatial price equilibrium. It is made operational by gravity-like specifications of the demand functions and is applied to a quantitative study of regional effects of the EEC and EFTA formation in Scandinavia and the FRG. Aggregated effects of integration on regional output are presented, based on a hypothetical pre-integration versus post-integration comparison for 1970. It is shown that, contrary to the common views, European economic integration has not been generally detrimental to geographically peripheral areas.     

Classification and benchmark of City Logistics measures: an empirical analysis

Urban freight distribution accounts for a significant share of pollution and congestion in urban areas. To reduce these negative impacts, municipalities have implemented several City Logistics (CL) measures. This paper presents the empirical analysis of a dataset of 70 European cities that have been piloting or rolling out a CL measure, to provide an updated indication of the status of CL initiatives and analyse the diffusion of CL internationally. The research objective is also to help understand the contextual factors might explain their introduction. To this end, a set of City Logistics Indices (CLI) is used as indicators of the breadth and number of CL measures implemented in a city. A statistical correlation of these CLIs with respect to a set of independent variables, namely the contextual factors, is also performed. Results reveal that the level of pollution, the diffusion of e-commerce and GDP are important drivers of CL deployment.     

三项举措应对物业服务价格松绑

<正>通过各方的努力,放开物业服务收费价格一定会让物业管理迎来新的发展,更有利于促进社区和谐建设。非保障性住房物业服务价格的放开,一时间成为业界议论的热点。许多业主担心物业服务企业会任性涨价,这也为政府管理部门提出了课题。笔者以为,政府监管部门应从以下几个方面入手应对物业服务价格的放开。     

Multi-objective linear programming with partial ranking of objectives

This paper is concerned with multi-objective linear programming problems in which the objective functions can be partially ranked. We represent the set of admissible weight vectors by a system of linear constraints and solve for the policy most likely to be optimum. If each admissible weight vector has the same probability of being correct, the optimum policy maximizes the hypervolume of the polytope of weight vectors having this policy as a solution. The proposed algorithm requires the enumeration of the subset of admissible efficient solutions of a multi-objective linear program. For each admissible solution, we estimate the ratio of the volumes of the corresponding polytope of weight vectors and the polytope of all admissible weight vectors. An algorithm is outlined for numerical integration using the Monte Carlo method. The model is extended to the case where several objectives are expressed as linear constraints with multiple parameter vectors and there is uncertainty about the weighting of these parameters. A numerical example is provided.     

The Kornai effect with partial bailouts and taxes

The model examines Kornai's observation that in the presence of bailouts, firms' demand for inputs will be greater than would otherwise be the case. This conjecture is examined in a model in which both revenue and cost uncertainty are present and in which firms making losses are partially subsidized and firms making positive profits are partially taxed. The Kornai effect is more prevalent the greater the subsidy rate, the smaller the tax rate and the greater the variance of the random variables through which uncertainty manifests itself. In the case of strongly positively correlated cost and revenue uncertainty, the absolute incidence of the Kornai effect is small.     

混凝土泵堵管故障分析及预防措施

泵送混凝土因作业速度快、生产效率高、劳动强度低而被施工单位广泛使用,但泵送过程中的堵管是经常出现的难以处理的问题。文章对泵送混凝土堵管的原因进行了分析,提出了解决办法和预防措施。     

关于300MW发电机的不对称运行性能分析及措施

文章以某火力发电厂的300 MW发电机组为研究对象,分析了其不对称运行产生的原因、危害,并从理论上有针对性地提出了发电机组网侧和转子侧控制策略,以期为相关实际应用提供参考。