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1.
This study was prompted by a recently published article in this journal on facility location by D. R. Sule. We show that the claim made by Sule of a novel and extremely simple algorithm yielding optimum solutions is not true. Otherwise, the algorithm would represent a breakthrough in decision-making for which a number of notoriously hard problems could be efficiently recast as location problems and easily solved.In addition, several variants of common location problems addressed by Sule are reviewed. In the last twenty years, many methods of accurately solving these problems have been proposed. In spite of their increased sophistication and efficiency, none of them claims to be a panacea. Therefore, researchers have concurrently developed a battery of fast but approximate solution techniques. Sule's method was essentially proposed by Kuehn and Hamburger in 1963, and has been adapted many times since.We exhibit several examples (including the one employed by Sule) in which Sule's algorithms lead to nonoptimal solutions. We present computational results on problems of size even greater than those utilized by Sule, and show that a method devised by Erlenkotter is both faster and yields better results.In a cost-benefit analysis of exact and approximate methods, we conclude that planning consists of generating an array of corporate scenarios, submitting them to the “optimizing black box,” and evaluating their respective merits. Therefore, much is to be gained by eliminating the vagaries of the black box—that is, by using an exact method—even if the data collection and the model representation introduce sizable inaccuracies. Ironically, large problems (those that typically require most attention) cannot be solved exactly in acceptable computational times. Pending the imminent design of a new generation of exact algorithms, the best heuristics are those that guarantee a certain degree of accuracy of their solutions.  相似文献   

2.
The planar minisam (‘median’) and minimax (‘center’) facility location problems are examined under the assumptions that: demand is continuously and uniformly distributed: the L1 (right-angle) metric is in use; and the planar region is traversed by a high-speed corridor (highway) running parallel to one of the directions of travel. For the minisum problem in a rectangular region, it is shown that, for any combination of problem parameters, there are only two candidate points in the region for the optimum location of the facility. This is also shown to be true for any convex and symmetric planar region. For the minimax problem in a rectangular region, there are only three candidate points for the optimal location. Some extensions and conjectures for the minisum problem involving more than one highway are also discussed.  相似文献   

3.
A.R. Banai-Kashani 《Socio》1984,18(3):159-166
Several theories, concepts, methods, or alternatively, “paradigms” have been suggested for the explanation and prediction of the location behavior of urban households. Increasingly, hwoever, “behavioral” approaches to the explanation of the dimensions of “choice” and/or exploration of alternative hypotheses have been cumbersome in the “mechanistic” paradigms of the social system and its related subsystems.An alternative paradigm of Analytic Hierarchy Process (AHP) is proposed to explore alternative structural specification hypotheses (sequential versus simultaneous) on the grouping and changing relative importance of “instrumental” and “non-instrumental” factors affecting location decision-making. AHP estimates of the “locational shares” of an urban (corridor) zonal population provide a paradigmatic basis for behavioral, vis-a-vis environmental, explanation of location decision-processes in a methodologically efficient, robust and theoretically inclusive framework of hierarchy systems.This paradigm is proposed for locational analysis requiring an effective integration of multilevel, environmental (contextual) and behavioral measures of relative importance, with limited data, and, for multidimensional problems in planning and policy-making, formidably requiring the integration of positive with normative analysis of systems.  相似文献   

4.
西方城市公共服务设施区位研究进展   总被引:7,自引:0,他引:7  
通过梳理国外公共服务设施区位理论的发展以及近年来研究的新动向,提出了对我国城市公共服务设施区位研究的展望。  相似文献   

5.
声发射源定位是声发射检测技术的主要目标之一,其准确程度反映了声源的检测位置和实际活动缺陷源位置的符合程度。文章系统阐述了目前声发射定位的各种方法及其优缺点,并展望了声发射源定位技术的发展趋势。  相似文献   

6.
In a proportional representation system, apportionment methods are used to round the vote proportion of a party to an integer number of seats in parliament. Assuming uniformly distributed vote proportions, we derive the seat allocation distributions for stationary divisor methods. An important characteristic of apportionment methods are seat biases, that is, expected differences between actual seat numbers and ideal shares of seats, when the parties are ordered from largest to smallest. We obtain seat bias formulas for the stationary divisor methods and for the quota method of greatest remainders.Acknowledgement. We thank Friedrich Pukelsheim for many fruitful discussions.Received March 2004  相似文献   

7.
Daskin's MEXCLP model [Daskin M. A maximum expected covering location model: formulation, properties, and heuristic solution. Transportation Science 1983;17:48-70] was one of the first efforts to capture the stochastic nature of emergency medical services (EMS) location problems within a mixed-integer formulation. With their subsequent introduction of MALP, ReVelle and Hogan [The maximum availability location problem. Transportation Science 1989;23:192-200] offered two key advances, local vehicle busyness estimates and the α-reliability objective. While these constructs have influenced many subsequent EMS location models, they have been subjected to relatively little empirical analysis. To address this, we introduce the LR-MEXCLP, a hybrid model combining the local busyness estimates of MALP with the maximum coverage objective of MEXCLP. We then solve a series of problems with all three models and employ simulation to estimate aggregate service levels. We find that LR-MEXCLP leads to modest but consistent service gains over both MALP and MEXCLP. These results support the merits of local busyness estimates, but they also suggest that the α-reliability objective may be inappropriate when seeking to maximize aggregate system response capabilities. More generally, our research underscores the utility of (a) linking modeling assumptions and goals with real-world application contexts, and (b) employing simulation or other techniques to validate theoretical results.  相似文献   

8.
I. Thomsen 《Metrika》1976,23(1):15-25
Summary In this article, we shall present an approximately optimal method for constructing stratum boundary points when the sample is allocated proportionally. The method is based on an equal partitioning of the cumulative off 1/3, wheref is the distribution of the stratification variable. We show that in many practical situations this technique compares favourably with approximately optimal stratification and allocation methods previously suggested.
Zusammenfassung In diesem Artikel stellen wir eine annähernd optimale Methode zur Festlegung von Stratabegrenzungspunkten dar, die für proportional angeordnete Samples gilt. Die Methode basiert auf einer gleichen Einteilung derf 1/3-Kummulation, wobeif die Verteilung der Stratifikations-variablen darstellt. Wir zeigen, daß diese Technik in vielen praktischen Fällen gegenüber den bisher vorgeschlagenen Methoden zur optimalen Stratifikation und Zuordnung nicht schlecht abschneidet.
  相似文献   

9.
This paper is a commentary on the work of Butt and Cavalier (Socio-Econ. Plann. Sci. 31(2) (1997) 103), a paper that was published in an earlier issue of this journal. With the aid of an example problem, we demonstrate that the set of gridlines proposed by them to find the rectilinear least cost path between two points in the presence of convex polygonal congested regions is inadequate. We proceed to prove its adequacy for the case of rectangular congested regions in which the edges of the rectangles are parallel to the travel directions. In wake of the difficulties of the general problem, we consider a specific example of a convex quadrilateral congestion region and a pair of external origin and destination points. Finally, we revisit the example shown in Butt and Cavalier's paper and present a mixed integer linear programming formulation that determines the optimal locations of the entry and exit points for this example.  相似文献   

10.
This note considers the equilibrium outcomes of the preference revelation games in the general model of indivisible good allocation introduced by [Sönmez, T., 1999. Strategy-proofness and essentially single-valued cores. Econometrica 67, 677–689]. We adopt the concepts of coalitional equilibria and cores which are both defined in terms of the weak deviation or blocking by a prescribed class of admissible coalitions. We prove that if the solution which induces preference revelation games is individually rational and Pareto optimal and the class of admissible coalitions is “monotonic,” then the set of coalitional equilibrium outcomes coincides with the core. And we point out that the preceding analysis in the context of marriage problems [Gale, D., Shapley, L., 1962. College admissions and the stability of marriage. American Mathematical Monthly 69, 9–15] is hardly extended to the general model.  相似文献   

11.
在实际生产中,立体仓库不停地进行出入库作业,同时还要求入库货物必须满足"上轻下重"原则,这对货位分配方案的实时性和可靠性以及动态优化提出较高要求.  相似文献   

12.
采用货运配送中心最新分拣系统使系统的维护更加容易,处理货物范围更广,适用于集装箱自动搬运。  相似文献   

13.
In this paper we present the problem of locating a facility when competition from another facility is taken into consideration. Two problems are addressed here. One is the location of a new facility that will attract the most buying power from an existing facility. The other is the location of a facility that will secure the most buying power againts the best location of competing facility to be set up in the future.  相似文献   

14.
Many cities are considering introducing or expanding rail service in an effort to diversify their modal splits. Park-and-rides are integral to this strategy because they represent private auto users’ access points to the system. Proper placement of such facilities is a strategic location decision, as it can conceivably decrease vehicular traffic on congested roadways while benefiting users. This paper models the decision to locate park-and-ride facilities in a network flow-based framework. From this perspective, optimal placement occurs at locations where vehicles will encounter facilities early during their journeys to a centralized area or major activity center. Locating park-and-rides in this fashion maximizes the chances of removing users from the network. These elements are demonstrated in three hypothetical placement scenarios that make use of synthetic network and traffic flow data. Results illustrate the functionality of our approach for identifying park-and-ride candidate locations. Lastly, implications of our work are discussed in light of broader planning concerns and practical demands on rail facility location.  相似文献   

15.
李萍 《企业技术开发》2006,25(8):89-90,112
会计电算化对我国企业的发展起到了极大的推动作用,但是随着会计电算化的飞速发展,实践工作中也出现了一些新的问题,阻碍了会计电算化向更深层次的发展,文章针对这些问题进行了阐述并提出相应的对策。  相似文献   

16.
Most models of resource allocation activity usually assume either a black box or a simple pyramidal hierarchy of black boxes as the organizational context for decision making. However, there are a number of resource allocation activities that take place in more complex hierarchies. These cases have been slighted by researchers, in part, because of a lack of practicable models. This paper presents a multiple-criterion resource allocation model specifically directed towards non-pyramidal hierarchies and other more complex organizational structures. A number of examples are discussed and a numerical example is presented.  相似文献   

17.
Summary Recently, Bischoff and Fieger (1992) considered the classical problem of estimating a bounded normal mean when the loss is thep-th power of the error. They proved that forp>-2 a two point prior is least favourable in case the parameter interval is small enough. In the present paper it is shown that this result remains valid forp>1. Moreover, the normal family is generalized to location parameter families. Finally, it is proved that no two point prior is least favourable for absolute error loss, i.e., forp=1.  相似文献   

18.
The flow-refueling location problem for alternative-fuel vehicles   总被引:3,自引:0,他引:3  
Beginning with Hodgson (Geogr.Anal.22(1990) 270), several researchers have been developing a new kind of location-allocation model for “flow capturing.” Instead of locating central facilities to serve demand at fixed points in space, their models aim to serve demand consisting of origin-destination flows along their shortest paths. This paper extends flow-capturing models to optimal location of refueling facilities for alternative-fuel (alt-fuel) vehicles, such as hydrogen fuel cells or natural gas. Existing flow-capturing models assume that if a flow passes just one facility along its path, it is covered. This assumption does not carry over to vehicle refueling because of the limited range of vehicles. For refueling, it may be necessary to stop at more than one facility in order to successfully refuel the entire path, depending on the vehicle range, the path length, and the node spacing. The Flow Refueling Location Model (FRLM) optimally locates p refueling stations on a network so as to maximize the total flow volume refueled. This paper presents a mixed-integer programming formulation for the nodes-only version of the problem, as well as an algorithm for determining all combinations of nodes that can refuel a given path. A greedy-adding approach is demonstrated to be suboptimal, and the tradeoff curve between number of facilities and flow volume refueled is shown to be nonconvex.  相似文献   

19.
项坚煜  王静 《价值工程》2011,30(28):138-139
目的:实现简略寿命表的快速计算。方法:利用Excel2000,输入、编辑、存储数据;利用VC++6.0设计用户操作界面及算法。结果:通过用户界面,实现对人员结构表的快速读入、死亡信息表的快速统计和简略寿命表的快速计算。结论:极大地提高了简略寿命表的编制速度,特别是当死亡信息表数据量巨大或数据频繁变动时,提速效果逾发显著。  相似文献   

20.
This article analyzes some of the major factors affecting the content and process of training paraprofessionals in state-run psychiatric hospitals. It reflects on the challenge of providing the relevant knowledge and skills for staff members with limited or no clinical experience yet who are expected to provide the highest quality of care in a rapidly changing field. The author uses her own experience at the only state-run psychiatric hospital in Delaware to present ideas of how to create a learning environment for paraprofessionals that could be transferred to similar facilities.  相似文献   

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