Measurement error and panel data1

The underidentification of linear models with measurement error does not necessarily extend to panel data models, as has been shown by GAiliches and Hausman (1986). We discuss and extend some of their results for a simple case and address particular issues concerning identification and asymptotic variances.     

Restricted maximum likelihood estimation under Eisenhart model Ill

For a balanced two-way mixed model, the maximum likelihood (ML) and restricted ML (REML) estimators of the variance components were obtained and compared under the non-negativity requirements of the variance components by L ee and K apadia (1984). In this note, for a mixed (random blocks) incomplete block model, explicit forms for the REML estimators of variance components are obtained. They are always non-negative and have smaller mean squared error (MSE) than the analysis of variance (AOV) estimators. The asymptotic sampling variances of the maximum likelihood (ML) estimators and the REML estimators are compared and the balanced incomplete block design (BIBD) is considered as a special case. The ML estimators are shown to have smaller asymptotic variances than the REML estimators, but a numerical result in the randomized complete block design (RCBD) demonstrated that the performances of the REML and ML estimators are not much different in the MSE sense.     

基于遗传算法的多目标集装箱多式联运运输优化模型

基于集装箱多式联运在进行门到门的运输过程中可以选择多种运输方式和路径的组合进行优化运输这个特点，本文将多式联运的运输优化问题转化成为一个最短路径问题，以成本和时间为优化目标建立了选择最优路径的模型，并选择遗传算法作为求解算法对实例问题进行了求解验证。     

物流企业开展TIR运输业务研究

针对TIR运输,通过分析其具有的可简化通关程序、提高运输时效等优势,结合当前我国全面开放跨境道路运输的利好政策,提出了我国物流企业开展TIR运输业务的建议,以推动我国物流企业TIR运输业务的发展。     

Optimal distribution of the injured in a multi-type transportation network with damage-dependent travel times: Two metaheuristic approaches

We study a location-allocation-routing problem for distribution of the injured in a disaster response scenario, considering a three-type transportation network with separate links. A circle-based approach to estimate the impacts of the disaster is presented. After formulating relations for computing the percentage of the injured, the destruction percentage and the damage-dependent travel times, the problem is formulated as an integer nonlinear program. We utilize a genetic algorithm and a discrete version of the imperialist competitive algorithm for solving large problems. An empirical study focused on earthquakes in Tabriz, Iran, illustrates applicability of the proposed model and performance of the proposed algorithms.     

基于灰色关联分析的汽车运输分队保障效能评估研究

将基于层次分析法的灰色关联分析引入军事物流运输环节的汽车运输分队保障效能评估中,通过确定评估对象、构造评估因素集等步骤,建立汽车运输分队保障效能评估模型,并通过实例,证明了该方法的正确性和实用性。     

航运联盟下的集装箱运输路径选择研究

首先分析了班轮运输的变化现状,然后运用系统分析的方法,研究运输网络的整体最优。结合集装箱运输具体的特性,构造了一整体最优情况下,各集装箱路径选择的模型。对班轮公司的日常经营调度、航线规划等有较大的参考意义。     

浅谈有线数字电视系统的调试与维护

文章介绍了有线数字电视的基本特点、系统指标、应用以及有线数字电视传输系统的维护,阐明了有线数字电视系统常见故障处理方法。     

八面台油田翻斗计量影响因素研究

八面台油田是一个特低渗透率热水掺输集油流程的低产油田,投入开发以后单井采用的计量方式主要有：单井罐检尺计量、远传示功图折产、玻璃管量油、计量车井口量油、翻斗量油．其中翻斗计量方式应用最为广泛。重点对影响翻斗计量准确性的各种因素进行了研究,针对存在的问题,提出了相应的改进意见。     

Numerical and analytical results for the transportation problem of Monge-Kantorovich

The Monge-Kantorovich transportation problem has a long and interesting history and has found a great variety of applications (see Rachev and Rüschendorf (1998a,b)). Some interesting characterizations of optimal solutions to the transportation problem (resp. coupling problems) have been found recently. For the squared distance and discrete distributions they relate optimal solutions to generalized Voronoi diagrams. Numerically we investigate the dependence of optimal couplings on variations of the coupling function. Numerical results confirm also a conjecture on optimal couplings in the one-dimensional case for nonconvex coupling functions. A proof of this conjecture is given under some technical conditions. Received: November 1999