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排序方式: 共有88条查询结果,搜索用时 234 毫秒
51.
M. John Hodgson 《European Journal of Operational Research》1981,6(2):199-204
Location—allocation models typically locate facilities with respect to points to be served, for example to the homes of potential patrons. Certain types of facility, however, are employed by persons who travel to the facility from their homes and continue their journey to another location. Child care facilities are an example of this pattern of patronage, with parents dropping children off at a centre en route to work. The paper presents a discrete-space location—allocation model minimizing the diversion of patrons' journeys to work. The problem reduces to the structure and combinatorial dimensions of the simple P-median problem. The model is applied to the transit worktrip patterns of single parents in Edmonton, Canada. The facilities generated by the model tend to central locations in the city where workplaces are concentrated and transit connections are efficient. The model provides a compromise between ones minimizing home-facility travel times and facility-workplace travel times. 相似文献
52.
P. A. Baxa 《Il Nuovo Cimento C》1982,5(6):649-671
Summary We study in this paper the position and the characteristics of the equilibrium points of a planet gravitational potential
as functions of theJ
22 parameter under the assumption that the potential is truncated to the first tesseral harmonicV=V
o+J22V22. The variational equations are solved analytically in the neighbourhood of these points to determine the possible periodic
orbits of a stationary satellite in the equatorial plane. A numerical investigation of the problem is reported with the presentation
of some periodic orbits of different families of stable and unstable type.
Riassunto Nel presente articolo si studiano i punti di equilibrio del potenziale gravitazionale di un pianeta in funzione del parametroJ 22 e nell'ipotesi che detto potenziale sia troncato alla prima armonica tesserale. Si risolvono inoltre le equazioni variazionali nell'intorno di detti punti al fine di determinare le possibili orbite periodiche di un satellite stazionario nel piano equatoriale. è riportata pure un'indagine numerica del problema con la presentazione di alcune orbite periodiche stabili ed instabili appartenenti a diverse famiglie.相似文献
53.
发展电动公交能减少燃油消耗和城市污染物排放,对改善城市环境具有十分重要的意义.提出一种能显著减少电动公交运营成本的直流快速充电方式及相应的充电设施的建设模式.对公交枢纽直流快速充电模式下电动公交充电服务排队模型、高峰和平峰期充电设施最优配置模型进行了研究,并通过算例验证了这些模型的有效性.研究成果对我国电动公交的充电设施建设具有借鉴意义. 相似文献
54.
55.
了对短周期风洞实验中,实验段建立起周期性稳定流动的时间进行估算,以便在实验中把握测量时间,保证测量数据的有效性和推确性,本文采用显式时间推进方法求解二维Euler方程对短周期风洞中二维涡轮叶栅的非定常流动进行了模拟。除预测建立起周期性稳定流动过程中的流场特征和达到周期性稳定流动所需的时间外,对叶片的升力等冲击载荷在建立起周期性稳定流动过程中的变化也进行了估算,为三维涡轮部件瞬态实验方案的规划和实验设备的研制提供帮助 相似文献
56.
57.
P. Hungerländer 《Optimization》2017,66(10):1699-1712
We suggest a new variant of a row layout problem: Find an ordering of n departments with given lengths such that the total weighted sum of their distances to a given checkpoint is minimized. The Checkpoint Ordering Problem (COP) is both of theoretical and practical interest. It has several applications and is conceptually related to some well-studied combinatorial optimization problems, namely the Single-Row Facility Layout Problem, the Linear Ordering Problem and a variant of parallel machine scheduling. In this paper we study the complexity of the (COP) and its special cases. The general version of the (COP) with an arbitrary but fixed number of checkpoints is NP-hard in the weak sense. We propose both a dynamic programming algorithm and an integer linear programming approach for the (COP) . Our computational experiments indicate that the (COP) is hard to solve in practice. While the run time of the dynamic programming algorithm strongly depends on the length of the departments, the integer linear programming approach is able to solve instances with up to 25 departments to optimality. 相似文献
58.
João C. Teixeira João F. Bigotte Hugo M. Repolho António P. Antunes 《European Journal of Operational Research》2019,272(2):608-620
Location modeling techniques have been applied to an extremely wide variety of public facilities. However, their application to one of the most ubiquitous public facilities – courts of justice – has been very rare. In this paper, we describe a study promoted by the Ministry of Justice of Portugal to define a proposal for the country's new judiciary map – that is, the spatial organization of the judicial system. The new map aims to promote the efficiency and specialization of the justice system (leading to better and faster court decisions) and to provide a good level of accessibility to courts. We developed two optimization models addressing those goals – a districting model, to determine the borders of new, large judicial districts; and a court location model, to determine the location, type, size, and coverage area of the courts included in each new district. Both models are discrete facility location models and consider hierarchical facilities – generic courts and specialized courts of multiple types. Our study was publicly acknowledged by the Portuguese government as having contributed to the new judiciary map that has since been approved and implemented. 相似文献
59.
Let a connected undirected graph G = (V, E) be given. In the classical p-median problem we want to find a set X containing p points in G such that the sum of weighted distances from X to all vertices in V is minimized. We consider the semi-obnoxious case where every vertex has either a positive or negative weight. In this case
we have two different objective functions: the sum of the minimum weighted distances from X to all vertices and the sum of the weighted minimum distances. In this paper we show that for the case p = 3 an optimal solution for the second model in a tree can be found in O(n
5) time. If the 3-median is restricted to vertices or if the tree is a path then the complexity can be reduced to O(n
3).
This research has partially been supported by the Spezialforschungsbereich F 003 “Optimierung und Kontrolle”, Projektbereich
Diskrete Optimierung. 相似文献
60.
J.J. Saameño Rodríguez C. Guerrero García E. Mérida Casermeiro 《Operations Research Letters》2006,34(4):427-436
In this paper, a finite set in which an optimal solution for a general Euclidean problem of locating an undesirable facility in a polygonal region, is determined and can be found in polynomial time. The general problem we propose leads us, among others, to several well-known problems such as the maxisum, maximin, anticentdian or r-anticentrum problem. 相似文献