不同环保意识视角下的DEA效率模型

DEA在效率分析领域具有良好的应用,随着全球气候的不断恶劣和环境的逐渐破坏,公众环保意识不断增强,在进行相关效率研究时,非期望产出越来越受到重视。以非期望产出为主要研究点,根据社会对非期望产出指标的认识规律将环保意识分为五个不同阶段,并综合考虑每个意识阶段的特征,将环境指标变动能力,环境承载能力、环境负外部性参与度、外部环境政策管理及企业生产要求纳入DEA效率分析过程中,通过对目标函数和约束条件进行不同的改进和约束,构建了不同意识阶段的DEA效率分析模型,并探讨了各阶段模型的使用范围和相互关系。最后,选取一个实例进行试算,证明各DEA模型的可行性和有效性。     

Comparison of adjoint‐based and feature‐based grid adaptation for functional outputs

Adjoint‐based and feature‐based grid adaptive strategies are compared for their robustness and effectiveness in improving the accuracy of functional outputs such as lift and drag coefficients. The output‐based adjoint approach strives to improve the adjoint error estimates that relate the local residual errors to the global error in an output function via adjoint variables as weight functions. A conservative adaptive indicator that takes into account the residual errors in both the primal (flow) and dual (adjoint) solutions is implemented for the adjoint approach. The physics‐based feature approach strives to identify and resolve significant features of the flow to improve functional accuracy. Adaptive indicators that represent expansions and compressions in the flow direction and gradients normal to the flow direction are implemented for the feature approach. The adaptive approaches are compared for functional outputs of three‐dimensional arbitrary Mach number flow simulations on mixed‐element unstructured meshes. Grid adaptation is performed with h‐refinement and results are presented for inviscid, laminar and turbulent flows. Copyright © 2006 John Wiley & Sons, Ltd.     

多投入多产出效率测量与影响因素判断

多投入多产出效率的测量是极为重要的,而更为重要的是判断究竟是什么因素影响了效率,因为后者能为科学决策提供有力依据。本文提出按效率与影响因素相关系数最大化来确定投入与产出的权重,从而计算效率的方法,并同时识别了影响因素。本文还用该方法给出了一个算例,其结论颇有启发。结果表明,该方法对于多投入、多产出的效率问题的测量与多影响因素的判断相当有效。     

Network DEA approach to airports performance assessment considering undesirable outputs

In this paper, a directional distance approach is proposed to deal with network DEA problems in which the processes may generate not only desirable final outputs but also undesirable outputs. The proposed approach is applied to the problem of modelling and benchmarking airport operations. The corresponding network DEA model considers two process (Aircraft Movement and Aircraft Loading) with two final outputs (Annual Passenger Movement and Annual Cargo handled), one intermediate product (Aircraft Traffic Movements) and two undesirable outputs (Number of Delayed Flights and Accumulated Flight Delays). The proposed approach has been applied to Spanish airports data for year 2008 comparing the computed directional distance efficiency scores with those obtained using a conventional, single-process directional distance function approach. From this comparison, it can be concluded that the proposed network DEA approach has more discriminatory power than its single-process counterpart, uncovering more inefficiencies and providing more valid results.     

Estimating the technical efficiency of health care systems: A cross-country comparison using the directional distance function

Economic activity produces not only desirable outputs but also undesirable outputs. Undesirable outputs are usually omitted from efficiency assessments (i.e., applications of Data Envelopment Analysis) which fail to express the true production process. The directional distance function model has been used for handling asymmetrically both desirable and undesirable outputs in the assessment process. In the present paper, we apply a generalized directional distance function to measure the efficiency of the health systems of 171 countries. We incorporate both desirable and undesirable outputs into the efficiency assessment without transforming the latter type of outputs into inputs or into their inverse form, as is done in most of the extant studies that deal with the measurement of health efficiency. The methodology that we apply introduces a modified definition of the efficiency score which yields results consistent with those obtained from radial DEA models. In addition, our results are independent of the length of the direction vector.     

Measurement of simultaneous scale and mix changes in inputs and outputs using DEA facets and RTS

We show a new use of the efficient facets in DEA. Specifically, once we have identified all facets of the DEA technology, we are able to estimate the potential changes in some inputs and outputs, while fixing other inputs and outputs, ranges of simultaneous scale and mix changes in inputs and outputs, while proportionally increasing or decreasing other inputs and outputs, and, finally, the RTS. The proposed algorithms are applied to corporate planning processes of chemical companies.     

考虑非合意产出的全要素能源效率研究

本文运用1995-2008年中国省域面板数据,选择基于DEA前沿面方法的Malmquist指数模型,测算了不同非合意产出组合的全要素能源效率(TFEE),并对TFEE构成进行分解,检验TFEE收敛性。研究发现,考虑环境因素的不同产出组合的TFEE具有显著差异性;中国1995 2008年TFEE呈现U型演变特征;TFEE的提高主要来源于技术进步的贡献;区域TFEE差异大,节能潜力大;TFEE具有周期性波动演化的复杂特征。     

考虑服务水平的商业银行综合效率评价研究

商业银行是我国银行体系的主体,提高银行的经营效率和服务水平是当前金融改革的重点。已有的研究较多关注于银行的收益,对银行的非期望产出如呆坏账及服务水平等关注较少。本文运用多个处理非期望产出的DEA模型,对2008年中国商业银行的效率进行了评价分析。文章在改进熵DEA方法的基础上,利用指标体系对商业银行的综合效率进行了测度并对比了处于多模型条件下模型的区分度问题。研究结果显示,呆坏账、服务水平(等待时间)等非期望产出对商业银行的效率意义重大;股份制商业银行的效率普遍高于国有商业银行,因此国有商业银行的股份制改造是一个积极的方向。最后,根据实证分析的结果提出的效率改进建议对商业银行的自身发展和管理当局的改革规划都具有重要的指导意义。     

具有非期望产出的混联网络DEA模型

数据包络分析(DEA)是评价系统相对有效性的分析方法,网络DEA模型在评价企业的经济效益、管理效益等实际问题中有着广泛的应用.在网络DEA模型的基础上考虑非期望产出要素,提出了具有非期望产出的混联网络DEA模型.研究了新模型的系统弱DEA有效与各子阶段弱DEA有效之间的关系,找到了无效决策单元的无效阶段,通过有针对性的改进能够提高系统的整体效率.最后通过数值算例验证了模型的可行性.     

基于SBM-NS模型的环境效率评价

给出一种处理非期望产出的环境效率评价模型,一方面解决了投入松弛性的问题,另一方面也解决了非期望产出存在下的效率评价问题,且模型能够避免量纲不同和角度选择的差异带来的偏差和影响.最后通过实证说明模型的有效性.