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61.
Robust optimization for emergency logistics planning: Risk mitigation in humanitarian relief supply chains 总被引:1,自引:0,他引:1
Aharon Ben-Tal Byung Do Chung Supreet Reddy Mandala Tao Yao 《Transportation Research Part B: Methodological》2011,45(8):1177-1189
This paper proposes a methodology to generate a robust logistics plan that can mitigate demand uncertainty in humanitarian relief supply chains. More specifically, we apply robust optimization (RO) for dynamically assigning emergency response and evacuation traffic flow problems with time dependent demand uncertainty. This paper studies a Cell Transmission Model (CTM) based system optimum dynamic traffic assignment model. We adopt a min–max criterion and apply an extension of the RO method adjusted to dynamic optimization problems, an affinely adjustable robust counterpart (AARC) approach. Simulation experiments show that the AARC solution provides excellent results when compared to deterministic solution and sampling based stochastic programming solution. General insights of RO and transportation that may have wider applicability in humanitarian relief supply chains are provided. 相似文献
62.
Chao ZhangXiaojun Chen Agachai Sumalee 《Transportation Research Part B: Methodological》2011,45(3):534-552
Various models of traffic assignment under stochastic environment have been proposed recently, mainly by assuming different travelers’ behavior against uncertainties. This paper focuses on the expected residual minimization (ERM) model to provide a robust traffic assignment with an emphasis on the planner’s perspective. The model is further extended to obtain a stochastic prediction of the traffic volumes by the technique of path choice approach. We show theoretically the existence and the robustness of the ERM solution. In addition, we employ an improved solution algorithm for solving the ERM model. Numerical experiments are carried out to illustrate the characteristics of the proposed model, by comparing with other existing models. 相似文献
63.
In this paper, we reformulate conventional data envelopment analysis (DEA) models and propose a novel method for evaluating sustainability of suppliers in the presence of interval volume discount offers, fuzzy data, and ordinal data. To this end, we convert all data into interval data. To convert fuzzy data into interval data, we use nearest weighted interval approximation by applying weighting function and we convert each ordinal data into interval one. Then, using enhanced Russell model, interval efficiencies are obtained. After that, using preference degree approach, we rank suppliers. Finally, a case study is presented to illustrate our proposed approach. 相似文献
64.
65.
Pole location control design of an active suspension system with uncertain parameters 总被引:3,自引:0,他引:3
Valter J. S. Leite Pedro L. D. Peres 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2005,43(8):561-579
This paper addresses the problem of robust control design for an active suspension quarter-car model by means of state feedback gains. Specifically, the design of controllers that assure robust pole location of the closed-loop system inside a circular region on the left-hand side of complex plane is investigated. Three sufficient conditions for the existence of a robust stabilizing state feedback gain are presented as linear matrix inequalities: (i) the quadratic stability based gain; (ii) a recently published condition that uses an augmented space and has been here modified to cope with the pole location specification; (iii) a condition that uses an extended number of equations and yields a parameter-dependent state feedback gain. Unlike other parameter-dependent strategies, neither extensive gridding nor approximations are needed. In the suspension model, the sprung mass, the damper coefficient and the spring constant are considered as uncertain parameters belonging to a known interval (polytope type uncertainty). It is shown that the parameter-dependent gain proposed allows one to impose the closed-loop system pole locations that in some situations cannot be obtained with constant feedback gains. 相似文献
66.
M. M. Chatillon L. Jezequel P. Coutant P. Baggio 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(11):817-839
This paper presents a design methodology for the mechanical systems entitled First Design. It is based on a hierarchical organisation of the design, taking into account the notion of robustness at an early phase of the project. The aim is to improve the quality of the system in order to make it robust, less sensitive to the variability of the external parameters and design parameters. We distinguish two main stages of the design cycle: one concerning functional parameters and another concerning physical parameters. The methodology is based on simplified models, on sensitivity analysis and on robust multi-objective optimisation. As an example, the methodology will be applied to the optimisation of vehicle suspension system design parameters. For each stage of the hierarchical design, adapted simplified models, sensitivity analyses and optimisation processes will be studied and applied to our vehicle suspension system. 相似文献
67.
Efficiency in the operation of the Swedish motor-vehicle inspection monopoly was examined by analyzing data on all decision-making units related to production of inspection services during 1993. In addition, theoretically based arguments concerning some regulation problems are discussed. The results imply a fairly high level of technical efficiency, which might be explained by the extensive practice of yardstick-competition in the industry. The findings, based on a best-practice approach, do not indicate strong empirical evidence in support of a deregulation of the industry. However, the regulation problems discussed may provide motives for deregulation. 相似文献
68.
调速系统是船舶主机遥控系统的核心组成部分,目前国内外先进的船舶主机调速系统大多采用了数字式调速器,使主机遥控向“智能化”方向发展.常规的PID控制最主要的问题是参数整定问题,一旦整定完毕,在整个控制过程中将是固定不变的,而在实际系统中,由于过程中会出现状态和参数的不确定,系统很难达到最佳的控制效果,严重的话可能导致系统的不稳定.该文介绍了鲁棒PID控制在船舶主机转速系统中的应用,由仿真结果可知,该控制方法有良好的控制性能和鲁棒性. 相似文献
69.
基于闭环增益成形的鲁棒PID算法及在液位控制中的应用 总被引:7,自引:1,他引:6
基于闭环增益成形算法给出鲁棒 PID算法 ,并将之应用于水箱液位的控制中。比较本文鲁棒 PID算法和文献 [1 ]模糊控制算法的仿真结果 ,得出前者的控制性能优于后者 ,同时具有良好的鲁棒稳定性。本文提出的鲁棒 PID算法简单、实用。 相似文献
70.
Ports currently face increasing demands to address a variety of environmental issues and achieve sustainability objectives. Using insights from the resource-based view of firms, this study examines the link between economic performance (EP) and environmental performance (ENP) of the top 10 U.S. seaports. Geospatial modeling is used to capture pollution incidents that can be geographically dispersed; in addition, both a bootstrap data envelopment analysis (DEA) approach and an undesirable DEA model are used to measure port ENP and EP. Our findings are in general consistent with assertions that positive EP can be attained in conjunction with good environmental practices. Ports’ capabilities of strategic capital investment in physical assets, collaborative interorganizational processes, and performance monitoring are essential, while they pursue both economic and environmental goals simultaneously. 相似文献