固-流结构矩形掺杂声子晶体的滤波特性

利用一维固-流结构矩形掺杂声子晶体中弹性波横向受限的条件,推导出弹性波在一维固-流结构矩形掺杂声子晶体中各个模式满足的关系式.研究弹性波各模式的缺陷模随模式量子数和杂质厚度的变化规律.利用缺陷模随模式量子数的变化规律可以实现多通道滤波,利用缺陷模随杂质厚度的变化规律可以实现调谐滤波.     

固-液结构圆柱声子晶体中弹性波的模式和带隙

利用一维固-液结构圆柱声子晶体中弹性波横向受限的条件,推导弹性波在一维固-液结构圆柱声子晶体中各个模式满足的关系式,研究各个模式弹性波的特征.并用色散函数计算各模式弹性波的带隙随模式量子数和圆柱半径的变化规律.得出一维固-液结构圆柱声子晶体的带隙由模式量子数和圆柱半径确定.     

Multiperiod Mean-Variance Optimization with Intertemporal Restrictions

We investigate mean-variance optimization problems that arise in portfolio selection. Restrictions on intermediate expected values or variances of the portfolio are considered. Some explicit procedures for obtaining the solution are presented. The main advantage of this technique is that it is possible to control the intermediate behavior of a portfolio’s return or variance. Some examples illustrating these situations are presented. The first author received financial support from CNPq (Brazilian National Research Council) Grants 472920/03-0 and 304866/03-2, FAPESP (Research Council of the State of S?o Paulo) Grant 03/06736-7, PRONEX Grant 015/98, and IM-AGIMB.     

应用DGPS和平台罗经建立对地速度基准的方法研究

给出了一种海上试验时建立速度基准的方法，它是利用试验舰上已有的DGPS和平台罗经。这种方法在一定的海域和RBN／DGPS基准站几何尺度内可以满足测试对速度基准精度的要求。中对各种对精度影响因素进行了定量分析，并给出了应用时的约束条件。     

An optimization problem on subsets of the symmetric positive-semidefinite matrices

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.     

Ratio-based RTS determination in weight-restricted DEA models

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.     

Delay-independent absolute stability for time-delay Lur''e systems with sector and slope restricted nonlinearities

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.     

The measurement of relative efficiency using data envelopment analysis with assurance regions that link inputs and outputs

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.     

研发外包中考虑服务商道德风险与资金限制的支付契约

针对研发外包中服务商道德风险防范与激励问题,在考虑服务商自有资金限制下,设计了研发外包支付契约,分析了契约的特性。研究表明,服务商自有资金的多少会影响支付契约的激励效果。当服务商自有资金很少时,支付契约对道德风险的防范与激励效果较差。当服务商自有资金达到一定量时,随着自有资金的增多,支付契约的激励效果越来越强,特别的当服务商自有资金超过很大一个量时,支付契约能激励服务商实现系统最优的工作努力程度。     

Measuring overall efficiency and effectiveness using DEA

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.