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Facility location on a tree with maximum distance constraints
Abstracts in Location Analysis
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Facility location on a tree with maximum distance constraints I. Douglas Moon and Lee Papayanopoulos Computers and Operations Research Vol.22, No. 9, 1995, pp. 905-914 The problem is to find the minimum number of feasible locations for identical facilities in a tree network when each demand point requires a facility within a specified distance limit and each facility itself requires another facility within a certain proximity. We initially develop a tree-reducing procedure that eliminates some demand points on the basis of their facility requirements. Our location procedure then identifies the minimum number of facility sites in the reduced tree. The computational complexity of either procedure is linear in the number of demand points. Facility location in the presence of congested regions with the rectilinear distance metric Steven E. Butt and Tom M. Cavalier Socio-Economic Planning Science Vol. 31, No. 2, 1997, pp. 103-l 13 This paper considers the planar P-median problem in the presence of congested regions, where distances are measured with the rectilinear distance metric. We define a congested region as a convex polygonal area of the plane in which a new facility cannot be located but through which travel is permitted at an additional cost per unit distance. Based on these assumptions, we show that this constrained form of the planar P-median problem can be transformed into an equivalent unconstrained P-median problem on a network. Hence, this constrained form of the P-median problem is reduced to a combinatorial search where an optimal set of new facilities is chosen from a finite set of candidate points. Accommodating the rainy season in Third World location-allocation Joseph R. Oppong Socio-Economic Planning Science Vol. 30, No. 2, 1996, pp. 121-137
applications
While data limitations do not preclude the application of location-allocation (LA) models in the Third World, the socio-spatial circumstances in such locations are sufficiently different to warrant additional caution in applications. For example, the rainy season disrupts transportation and travel for long periods in many countries; yet, typical LA applications fail to consider it. Using the simple pmedian and coverage models, this study examines the effect of the rainy season on Third World LA applications. The results indicate that ignoring the rainy season can produce potentially disastrous results, while accommodating it, perhaps by simply editing the data, is likely to produce better results. Moreover, embedded values in these models influence locational outcomes. The results thus call for considerable caution in Third World LA applications.
A model for locating automatic external defibrillators Marvin B. Mandell and Les R. Becker Socio-Economic Planning Science Vol. 30, No. 1, 1996, pp. 51-66 Automatic external defibrillators (AEDs) enable basic life support (BLS) companies to resuscitate victims of out-of-hospital cardiac arrests (“heart attacks”) by automatically or semi-automatically providing an electrical countershock. Due to the cost of such devices, decision-makers in emergency medical service (EMS) systems often face the task of selecting those BLS units in the EMS system on which an AED should be placed. We thus present a multiobjective integer programming model, incorporating both equity and overall survival rates, to help decision-makers select BLS companies in a jurisdiction to equip with AEDs. The model can also accommodate restrictions that decision-makers might wish to impose in terms of specifying BLS units on which an AED must, or must not, be placed. In addition to the model itself, a heuristic solution procedure is presented. A case study in which the model was applied successfully is also described.
65
Facility location on a tree with maximum distance constraints I. Douglas Moon and Lee Papayanopoulos Computers and Operations Research Vol.22, No. 9, 1995, pp. 905-914 The problem is to find the minimum number of feasible locations for identical facilities in a tree network when each demand point requires a facility within a specified distance limit and each facility itself requires another facility within a certain proximity. We initially develop a tree-reducing procedure that eliminates some demand points on the basis of their facility requirements. Our location procedure then identifies the minimum number of facility sites in the reduced tree. The computational complexity of either procedure is linear in the number of demand points. Facility location in the presence of congested regions with the rectilinear distance metric Steven E. Butt and Tom M. Cavalier Socio-Economic Planning Science Vol. 31, No. 2, 1997, pp. 103-l 13 This paper considers the planar P-median problem in the presence of congested regions, where distances are measured with the rectilinear distance metric. We define a congested region as a convex polygonal area of the plane in which a new facility cannot be located but through which travel is permitted at an additional cost per unit distance. Based on these assumptions, we show that this constrained form of the planar P-median problem can be transformed into an equivalent unconstrained P-median problem on a network. Hence, this constrained form of the P-median problem is reduced to a combinatorial search where an optimal set of new facilities is chosen from a finite set of candidate points. Accommodating the rainy season in Third World location-allocation Joseph R. Oppong Socio-Economic Planning Science Vol. 30, No. 2, 1996, pp. 121-137
applications
While data limitations do not preclude the application of location-allocation (LA) models in the Third World, the socio-spatial circumstances in such locations are sufficiently different to warrant additional caution in applications. For example, the rainy season disrupts transportation and travel for long periods in many countries; yet, typical LA applications fail to consider it. Using the simple pmedian and coverage models, this study examines the effect of the rainy season on Third World LA applications. The results indicate that ignoring the rainy season can produce potentially disastrous results, while accommodating it, perhaps by simply editing the data, is likely to produce better results. Moreover, embedded values in these models influence locational outcomes. The results thus call for considerable caution in Third World LA applications.
A model for locating automatic external defibrillators Marvin B. Mandell and Les R. Becker Socio-Economic Planning Science Vol. 30, No. 1, 1996, pp. 51-66 Automatic external defibrillators (AEDs) enable basic life support (BLS) companies to resuscitate victims of out-of-hospital cardiac arrests (“heart attacks”) by automatically or semi-automatically providing an electrical countershock. Due to the cost of such devices, decision-makers in emergency medical service (EMS) systems often face the task of selecting those BLS units in the EMS system on which an AED should be placed. We thus present a multiobjective integer programming model, incorporating both equity and overall survival rates, to help decision-makers select BLS companies in a jurisdiction to equip with AEDs. The model can also accommodate restrictions that decision-makers might wish to impose in terms of specifying BLS units on which an AED must, or must not, be placed. In addition to the model itself, a heuristic solution procedure is presented. A case study in which the model was applied successfully is also described.