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21.
Motivated by the metricsstress problem in multidimensional scaling, the authors consider the more general problem of minimizing a strictly convex function on a particular subset ofR
n × n
. The subset in question is the intersection of a linear subspace with the symmetric positive-semidefinite matrices of rank p. Because of the rank restriction, this subset is not convex. Several equivalent formulations of this problem are derived, and the advantages and disadvantages of each formulation are discussed.Part of this research was conducted while the authors were visitors at the Center for Research on Parallel Computation, Rice University, Houston, Texas. The first author was partially supported by National Science Foundation Grant RII-89-05080. 相似文献
22.
This paper provides computationally efficient approaches for determining to which returns to scale (RTS) class a unit belongs in weight-restricted Data Envelopment Analysis (DEA) models. A non-traditional computational algorithm is introduced. The suggested approach is based on the calculation of certain ratios within the data set and offers obvious computational advantages over the traditional approaches involving the solution of standard DEA models. Some theorems and algorithms are given. Computational advantages of the provided results are discussed and one of the algorithms is illustrated using real world data. 相似文献
23.
This Letter presents an analysis method for a delay-independent absolute stability of time-delay Lur'e systems with sector and slope restrictions. The proposed method is based on the Lyapunov functions with quadratic form of states and nonlinear functions of the systems. Several criteria are derived in terms of linear matrix inequalities (LMIs). A numerical example is illustrated to show the effectiveness of the proposed method. 相似文献
24.
M. Khalili A.S. Camanho M.C.A.S. Portela M.R. Alirezaee 《European Journal of Operational Research》2010
The most popular weight restrictions are assurance regions (ARs), which impose ratios between weights to be within certain ranges. ARs can be categorized into two types: ARs type I (ARI) and ARs type II (ARII). ARI specify bounds on ratios between input weights or between output weights, whilst ARII specify bounds on ratios that link input to output weights. DEA models with ARI successfully maximize relative efficiency, but in the presence of ARII the DEA models may under-estimate relative efficiency or may become infeasible. In this paper we discuss the problems that can occur in the presence of ARII and propose a new nonlinear model that overcomes the limitations discussed. Also, the dual model is described, which enables the assessment of relative efficiency when trade-offs between inputs and outputs are specified. The application of the model developed is illustrated in the efficiency assessment of Portuguese secondary schools. 相似文献
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This paper presents a framework where data envelopment analysis (DEA) is used to measure overall efficiency and show how to apply this framework to assess effectiveness for more general behavioral goals. The relationships between various cone-ratio DEA models and models to measure overall efficiency are clarified. Specifically it is shown that as multiplier cones tighten, the cone-ratio DEA models converge to measures of overall efficiency. Furthermore, it is argued that multiplier cone and cone-ratio model selection must be consistent with the behavioral goals assigned or assumed for purposes of analysis. Consistent with this reasoning, two new models are introduced to measure effectiveness when value measures are represented by separable or linked cones, where the latter can be used to analyze profit-maximizing effectiveness. 相似文献
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对光反馈自混合干涉信号波形转折点的智能识别进行了理论分析和实验研究。首先经对光反馈自混合干涉信号特点的分析,发现其波形转折点可以作为外部物体运动位移实时测量的依据。通过对信号波形的逐步处理可以获得波形转折点的位置,以此为基准点可以实现位移的精测。实验测试结果同理论分析吻合较好。若系统进入较复杂状态,识别出的位置与其实际位置出现偏差,不再是单一值,可以对转折点位置的所有值取平均,从而得到其对应的精确位置。 相似文献
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The law of one price in data envelopment analysis: Restricting weight flexibility across firms 总被引:4,自引:0,他引:4
Timo Kuosmanen Laurens Cherchye Timo Sipilinen 《European Journal of Operational Research》2006,170(3):735-757
The Law of One Price (LoOP) states that all firms face the same prices for their inputs and outputs under market equilibrium. Taken here as a normative condition for ‘efficiency prices’, this law has powerful implications for productive efficiency analysis, which have remained unexploited thus far. This paper shows how LoOP-based weight restrictions can be incorporated in Data Envelopment Analysis (DEA). Utilizing the relation between industry-level and firm-level cost efficiency measures, we propose to apply a set of input prices that is common for all firms and that maximizes the cost efficiency of the industry. Our framework allows for firm-specific output weights and for variable returns-to-scale, and preserves the linear programming structure of the standard DEA. We apply the proposed methodology to the evaluation of the research efficiency of economics departments of Dutch Universities. This application shows that the methodology is computationally tractable for practical efficiency analysis, and that it helps in deepening the DEA analysis. 相似文献