DEA-Nash约束均衡的城市竞争力评价模型研究——基于投入产出有效性的角度

建立了一类新的DEA模型,即DEA-Nash模型,并引入了超效率的DEA-NashSUP模型.该模型通过引入Nash约束参数,构造了Nash均衡约束,体现了完全竞争因素,克服了经典的CCR模型没有考虑竞争因素和有效单元过多时无法进行排序的的缺陷,得到了更具有现实意义的效率评价结果,并通过算例进行了演示.该模型适用于具有较强竞争性的评价对象体系进行效率评价,比如城市竞争力评价.     

基于DEA的城市客运换乘枢纽服务水平评价研究

为了对城市客运换乘枢纽服务水平进行有效的评价,找出其在运行过程中存在的问题并予以解决,建立了城市客运枢纽换乘服务水平评价体系,并利用数据包络分析(DEA)方法进行了有效分析;选取西安市地铁2号线北大街、小寨、钟楼等三个典型枢纽进行了实例分析。结果表明:DEA方法可以有效地应用于城市客运枢纽换乘服务水平评价中,并且为提升换乘枢纽服务水平提供了参考依据。     

稳健设计方法用于车门系统设计

将Taguch i稳健设计方法应用于车门系统设计。通过将试验设计与计算分析结合获取产品设计质量特性信息;通过实例说明将结构参数优化组合,提高车门铰接系统稳健性的方法。此方法的优点是可以从许多试验条件中选择出最有代表性的少数几项试验,获得可靠的试验结果,且分析计算简单,适用于多参数的产品优化设计。     

基于DEA的辽宁省公路网评价

在深入研究辽宁省公路网供类指标与需类指标的基础上,建立了科学实用的评价指标体系,设计了DEA评价模型,并通过2008年辽宁省各市公路网基础数据验证了模型的客观合理性,结果表明,该方法用于公路网方案综合评价是可行有效的。     

Improving recovery-to-optimality robustness through efficiency-balanced design of timetable structure

To improve the service quality of the railway system (e.g., punctuality and travel times) and to enhance the robust timetabling methods further, this paper proposes an integrated two-stage approach to consider the recovery-to-optimality robustness into the optimized timetable design without predefined structure information (defined as flexible structure) such as initial departure times, overtaking stations, train order and buffer time. The first-stage timetabling model performs an iterative adjustment of all departure and arrival times to generate an optimal timetable with balanced efficiency and recovery-to-optimality robustness. The second-stage dispatching model evaluates the recovery-to-optimality robustness by simulating how each timetable generated from the first-stage could recover under a set of restricted scenarios of disturbances using the proposed dispatching algorithm. The concept of recovery-to-optimality is examined carefully for each timetable by selecting a set of optimally refined dispatching schedules with minimum recovery cost under each scenario of disturbance. The robustness evaluation process enables an updating of the timetable by using the generated dispatching schedules. Case studies were conducted in a railway corridor as a special case of a simple railway network to verify the effectiveness of the proposed approach. The results show that the proposed approach can effectively attain a good trade-off between the timetable efficiency and obtainable robustness for practical applications.     

Railway transportation and environmental efficiency in China

Railway is one of the most efficient and environmental-friendly ways to transport people and goods. High-speed railway has been developing rapidly and the railway mileage has increased by 21.18% in China during the period of 2006–2011 and thus it is interesting to evaluate whether the railway transportation has reduced the environmental impact of transport in China. In this paper, we first use a non-radial DEA under managerial disposability to measure the environmental efficiency of 30 regions in China; then we propose a panel beta regression with fixed effects to model the impact of railway transportation on environmental efficiency. The results indicate that the environmental efficiency slowly increased during 2006–2011 and it exhibits regional disparities with the eastern area having the highest environmental efficiency and the western area being the lowest one; Moreover, we also find a significant positive impact of railway transportation on higher environmental efficiency.     

Robust supply vessel routing and scheduling

We solve the problem of tactical supply vessel planning arising in the upstream offshore petroleum logistics. Supply vessels deliver all the necessary materials and equipment to offshore installations from an onshore supply base according to a delivery schedule. The planning of supply vessels should be done so that their number is minimized and at the same time provide a reliable flow of supplies from the base. The execution of a weekly sailing plan is affected by weather conditions, especially in winter time. Harsh weather conditions increase the number of vessels required to perform the operations as well as the service times at the installations, and thus disrupt the schedule, leading to additional costs and reduced service level. We present a methodology for robust supply vessel planning enabling a trade-off analysis to be made between the schedules’ service level and vessels’ cost. The methodology involves the generation of multiple vessel schedules with different level of robustness using an adaptive large neighbourhood search metaheuristic and a subsequent discrete event simulation procedure for the assessment of the service level. To control the level of robustness we developed a concept of slacks and incorporated it into the metaheuristic algorithm.     

Robust transit network design with stochastic demand considering development density

This paper analyzes the influence of urban development density on transit network design with stochastic demand by considering two types of services, rapid transit services, such as rail, and flexible services, such as dial-a-ride shuttles. Rapid transit services operate on fixed routes and dedicated lanes, and with fixed schedules, whereas dial-a-ride services can make use of the existing road network, hence are much more economical to implement. It is obvious that the urban development densities to financially sustain these two service types are different. This study integrates these two service networks into one multi-modal network and then determines the optimal combination of these two service types under user equilibrium (UE) flows for a given urban density. Then we investigate the minimum or critical urban density required to financially sustain the rapid transit line(s). The approach of robust optimization is used to address the stochastic demands as captured in a polyhedral uncertainty set, which is then reformulated by its dual problem and incorporated accordingly. The UE principle is represented by a set of variational inequality (VI) constraints. Eventually, the whole problem is linearized and formulated as a mixed-integer linear program. A cutting constraint algorithm is adopted to address the computational difficulty arising from the VI constraints. The paper studies the implications of three different population distribution patterns, two CBD locations, and produces the resultant sequences of adding more rapid transit services as the population density increases.     

基于 DEA 的区域物流系统协同发展评价

区域物流系统协同发展状况直接影响区域内物流产业结构调整、空间布局和政策制定。以区域物流系统为研究对象,分析区域物流系统协同发展内涵和评价内容,综合利用数据包络分析（DEA ）和复合系统可持续发展评价方法,建立区域物流系统中子系统内部、子系统之间及系统整体协同发展效度模型,对其协同效度、发展效度和综合效度进行评价,并选取多个区域进行实证分析,得到各区域物流系统协同发展状况以及主要成因。结果表明集成利用数据包络分析法C2 R模型和C2 GS2在区域物流系统协同发展的有效性评价中具有很好的效果,结果更为客观。     

H∞ control design to include nonlinearities. Second report: nonlinearities in equations of motion

In our first report, a method to deal with the nonlinearity of saturation was proposed. A method of dealing with nonlinearity in equations of motion is proposed in this paper. The nonlinear equations of motion are expressed as variations of linear equations of motion. The nonlinear equations can be linearized around a specific point with a tangential plane or line. Accordingly, nonlinear equations effective in a certain domain can be obtained by variations in this tangential line. A control system with varying elements can be designed using the general H _∞ control theory. As an example, we present a speed and heading changing system for large vessels at low speeds during berthing maneuvers, where the equation will vary during motion. The nonlinearity of the equations is caused by the speeds. The control system is essentially designed to be robust in disturbance and noise. In this example, the saturation in the propeller is also considered using the method proposed in the first report. The results show that the method proposed in this paper is effective. Received: February 20, 2001 / Accepted: December 11, 2001