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Single Facility (single + facility)
Selected AbstractsExact optimal solutions of the minisum facility and transfer points location problems on a networkINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 3 2008Mihiro Sasaki Abstract We consider hierarchical facility location problems on a network called Multiple Location of Transfer Points (MLTP) and Facility and Transfer Points Location Problem (FTPLP), where q facilities and p transfer points are located and each customer goes to one of the facilities directly or via one of the transfer points. In FTPLP, we need to find an optimal location of both the facilities and the transfer points while the location of facilities is given in MLTP. Although good heuristics have been proposed for the minisum MLTP and FTPLP, no exact optimal solution has been tested due to the size of the problems. We show that the minisum MLTP can be formulated as a p -median problem, which leads to obtaining an optimal solution. We also present a new formulation of FTPLP and an enumeration-based approach to solve the problems with a single facility. [source] Nursing Time Devoted to Medication Administration in Long-Term Care: Clinical, Safety, and Resource ImplicationsJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2 2009Mary S. Thomson PhD OBJECTIVES: To quantify the time required for nurses to complete the medication administration process in long-term care (LTC). DESIGN: Time-motion methods were used to time all steps in the medication administration process. SETTING: LTC units that differed according to case mix (physical support, behavioral care, dementia care, and continuing care) in a single facility in Ontario, Canada. PARTICIPANTS: Regular and temporary nurses who agreed to be observed. MEASUREMENTS: Seven predefined steps, interruptions, and total time required for the medication administration process were timed using a personal digital assistant. RESULTS: One hundred forty-one medication rounds were observed. Total time estimates were standardized to 20 beds to facilitate comparisons. For a single medication administration process, the average total time was 62.0±4.9 minutes per 20 residents on physical support units, 84.0±4.5 minutes per 20 residents on behavioral care units, and 70.0±4.9 minutes per 20 residents on dementia care units. Regular nurses took an average of 68.0±4.9 minutes per 20 residents to complete the medication administration process, and temporary nurses took an average of 90.0±5.4 minutes per 20 residents. On continuing care units, which are organized differently because of the greater severity of residents' needs, the medication administration process took 9.6±3.2 minutes per resident. Interruptions occurred in 79% of observations and accounted for 11.5% of the medication administration process. CONCLUSION: Time requirements for the medication administration process are substantial in LTC and are compounded when nurses are unfamiliar with residents. Interruptions are a major problem, potentially affecting the efficiency, quality, and safety of this process. [source] An asymptotically optimal greedy heuristic for the multiperiod single-sourcing problem: The cyclic caseNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 5 2003H. Edwin Romeijn The dynamics of the environment in which supply chains evolve requires that companies frequently redesign their logistics distribution networks. In this paper we address a multiperiod single-sourcing problem that can be used as a strategic tool for evaluating the costs of logistics network designs in a dynamic environment. The distribution networks that we consider consist of a set of production and storage facilities, and a set of customers who do not hold inventories. The facilities face production capacities, and each customer's demand needs to be delivered by a single facility in each period. We deal with the assignment of customers to facilities, as well as the location, timing, and size of inventories. In addition, to mitigate start and end-of-study effects, we view the planning period as a typical future one, which will repeat itself. This leads to a cyclic model, in which starting and ending inventories are equal. Based on an assignment formulation of the problem, we propose a greedy heuristic, and prove that this greedy heuristic is asymptotically feasible and optimal in a probabilistic sense. We illustrate the behavior of the greedy heuristic, as well as some improvements where the greedy heuristic is used as the starting point of a local interchange procedure, on a set of randomly generated test problems. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 412,437, 2003 [source] The ,-reliable minimax and maximin location problems on a network with probabilistic weightsNETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2010Jiamin Wang Abstract We study the ,-reliable minimax and maximin location problems on a network when the weights associated with the nodal points are random variables. In the ,-reliable minimax (maximin) problem, we locate a single facility so as to minimize (maximize) the upper (lower) bound on the maximum (minimum) weighted distance from the nodes to the facility with a probability greater than or equal to a pre-specified level ,. It is shown that under some conditions the two probabilistic models are equivalent to their deterministic counterparts. Solution procedures are developed to solve the problems with weights of continuous and discrete probability distributions. © 2009 Wiley Periodicals, Inc. NETWORKS, 2010 [source] | ||||||||||