The differential evolution algorithm is an evolutionary algorithm for global optimization and the un-capacitated facility location problem (UFL) is one of the classic NP-Hard problems. In this paper, combined with the...The differential evolution algorithm is an evolutionary algorithm for global optimization and the un-capacitated facility location problem (UFL) is one of the classic NP-Hard problems. In this paper, combined with the specific characteristics of the UFL problem, we introduce the activation function to the algorithm for solving UFL problem and name it improved adaptive differential evolution algorithm (IADEA). Next, to improve the efficiency of the algorithm and to alleviate the problem of being stuck in a local optimum, an adaptive operator was added. To test the improvement of our algorithm, we compare the IADEA with the basic differential evolution algorithm by solving typical instances of UFL problem respectively. Moreover, to compare with other heuristic algorithm, we use the hybrid ant colony algorithm to solve the same instances. The computational results show that IADEA improves the performance of the basic DE and it outperforms the hybrid ant colony algorithm.展开更多
First a remanufactming logistics network is con- structed, in which the structure of both the forward logistics and the reverse logistics are of two levels and all the logistics facilities are capacitated. Both the re...First a remanufactming logistics network is con- structed, in which the structure of both the forward logistics and the reverse logistics are of two levels and all the logistics facilities are capacitated. Both the remanufactming products and the new products can be used to meet the demands of customers. Moreover, it is assumed that homogeneous facilities can be designed together into integrated ones, based on which a mixed integer nonlinear programming （MINLP） facility location model of the remanufacturing logistics network with six types of facilities to be sited is built. Then an algorithm based on enumeration for the model is given. The feasible combinations of binary variables are searched by enumeration, and the remaining sub-problems are solved by the LP solver. Finally, the validities of the model and the algorithm are illustrated by means of an example. The result of the sensitivity analysis of parameters indicates that the integration of homogeneous facilities may influence the optimal solution of the problem to a certain degree.展开更多
To smooth the correlation process from bio-virus diffusion to emergency relief response,the Gaussian plume model is used to describe the diffusion of dangerous sources,where the bio-virus concentration at any given po...To smooth the correlation process from bio-virus diffusion to emergency relief response,the Gaussian plume model is used to describe the diffusion of dangerous sources,where the bio-virus concentration at any given point in affected areas can be calculated.And the toxic load rule is introduced to define the borderline of the dangerous area at different levels.Combined with this,different emergency levels of different demand points in dangerous areas are confirmed using fuzzy clustering,which allows demand points at the same emergency level to cluster in a group.Some effective emergency relief centers are chosen from the candidate hospitals which are located in different emergency level affected areas by set covering.Bioterrorism experiments which were conducted in Nanjing,Jiangsu province are simulated,and the results indicate that the novel method can be used efficiently by decision makers during an actual anti-bioterrorism relief.展开更多
develop a mentation This paper considers the priority facility primal-dual 3-approximation algorithm for procedure, the authors further improve the location problem with penalties： The authors this problem. Combining...develop a mentation This paper considers the priority facility primal-dual 3-approximation algorithm for procedure, the authors further improve the location problem with penalties： The authors this problem. Combining with the greedy aug- previous ratio 3 to 1.8526.展开更多
Facility location problem is a kind of NP-Hard combinational problem.Considering ever-changing demand sites,demand quantity and releasing cost,we formulate a model combining tabu search and FCM(fuzzy clustering method...Facility location problem is a kind of NP-Hard combinational problem.Considering ever-changing demand sites,demand quantity and releasing cost,we formulate a model combining tabu search and FCM(fuzzy clustering method) to solve the capacitated dynamic facility location problem.Some results are achieved and they show that the proposed method is effective.展开更多
We study the mechanism design of facility location problems.The problem is to design mechanisms to select a set of locations on which to build a set of facilities,aiming to optimize some system objective and achieve d...We study the mechanism design of facility location problems.The problem is to design mechanisms to select a set of locations on which to build a set of facilities,aiming to optimize some system objective and achieve desirable properties based on the strategic agents'locations.The agents might have incentives to misreport their private locations,in order to minimize the costs(i.e.,the distance from the closest facility).We study the setting with limited locations,that is,the facilities can only be built on a given finite set of candidate locations,rather than the whole space.For locating a single facility and two facilities on a real line,we propose strategyproof mechanisms with tight approximation ratios,under the objectives of minimizing the total cost and the maximum cost.Further,we consider the problem of locating an obnoxious facility from which the agents want to stay as far away as possible,and derive tight bounds on the approximation ratio of strategyproof mechanisms.展开更多
Emergency response activity relies on transportation networks. Emergency facility location interacts with transportation networks clearly. This review is aimed to provide a combined framework for emergency facility lo...Emergency response activity relies on transportation networks. Emergency facility location interacts with transportation networks clearly. This review is aimed to provide a combined framework for emergency facility location in transportation networks. The article reveals emergency response activities research clusters, issues, and objectives according to keywords co-occurrence analysis. Four classes of spatial separation models in transportation networks, including distance, routing, accessibility, and travel time are introduced. The stochastic and time-dependent characteristics of travel time are described. Travel time estimation and prediction method, travel time under emergency vehicle preemption,transportation network equilibrium method, and travel time in degradable networks are demonstrated. The emergency facilities location models interact with transportation networks, involving location-routing model, location models embedded with accessibility,location models embedded with travel time, and location models employing mathematical program with equilibrium constraints are reviewed. We then point out the-state-of-art challenges: ilities-oriented, evolution landscape and sequential decision modelling, datadriven optimization approach, and machine learning-based algorithms.展开更多
In this paper,we consider the metric uncapacitated facility location game with service installation costs. Our main result is an 11-approximate cross-monotonic cost-sharing method under the assumption that the install...In this paper,we consider the metric uncapacitated facility location game with service installation costs. Our main result is an 11-approximate cross-monotonic cost-sharing method under the assumption that the installation cost depends only on the service type.展开更多
This paper considers a variant of the classical facility location game called the uncapacitared facility location game with penalties （UFLGWP）. Unlike the standard UFLG, each client in the UFLGWP is either assigned ...This paper considers a variant of the classical facility location game called the uncapacitared facility location game with penalties （UFLGWP）. Unlike the standard UFLG, each client in the UFLGWP is either assigned to an open facility or rejected by paying a penalty. The authors propose a 3-approximate cross-monotonic cost-sharing method for the UFLGWP.展开更多
We study the soft-capacitated facility location game which is an extension of the facility location game of Pa1 and Tardos. We propose a 6-approximate cross-monotonic cost-sharing method. Numerical tests indicate that...We study the soft-capacitated facility location game which is an extension of the facility location game of Pa1 and Tardos. We propose a 6-approximate cross-monotonic cost-sharing method. Numerical tests indicate that the method is effective.展开更多
Given m facilities each with an opening cost, n demands, and distance between every demand and facility, the Facility Location problem finds a solution which opens some facilities to connect every demand to an opened ...Given m facilities each with an opening cost, n demands, and distance between every demand and facility, the Facility Location problem finds a solution which opens some facilities to connect every demand to an opened facility such that the total cost of the solution is minimized. The κ-Facility Location problem further requires that the number of opened facilities is at most κ, where κ is a parameter given in the instance of the problem. We consider the Facility Location problems satisfying that for every demand the ratio of the longest distance to facilities and the shortest distance to facilities is at most ω, where ω is a predefined constant. Using the local search approach with scaling technique and error control technique, for any arbitrarily small constant ε 〉 0, we give a polynomial-time approximation algorithm for the ω-constrained Facility Location problem with approximation ratio 1 ＋ √ω ＋ ε, which significantly improves the previous best known ratio （ω ＋ 1）/α for some 1 ≤ α ≤2, and a polynomial-time approximation algorithm for the ω-constrained κ- Facility Location problem with approximation ratio ω ＋ 1 ＋ ε. On the aspect of approximation hardness, we prove that unless NP C DTIME（n^O（log log n））, the ω-constrained Facility Location problem cannot be approximated within 1 ＋ln √ω 1, which slightly improves the previous best known hardness result 1.243 ＋ 0.316 ln（ω - 1）. The experimental results on the standard test instances of Facility Location problem show that our algorithm also has good performance in practice.展开更多
In the k-level facility location problem with penalties,each client will be either serviced or rejected completely.And if the client is planned to be serviced,then it must be connected to a sequence of k different kin...In the k-level facility location problem with penalties,each client will be either serviced or rejected completely.And if the client is planned to be serviced,then it must be connected to a sequence of k different kinds of facilities located in k levels of hierarchy.The total cost including the facility cost,connection cost and penalty cost will be jointly paid by all the clients.In the corresponding game of the k-level facility location problem with penalties,called the k-level facility location game with penalties,the total cost should be allocated to different clients.This work set out a cost-sharing scheme for the k-level facility location game with penalties that is cross-monotonic,competitive,and the approximate cost recovery is 6.展开更多
We study the two-stage stochastic facility location problem(2-SFLP)by proposing an LP(location problem)-rounding approximation algorithm with 2.3613 per-scenario bound for this problem,improving the previously best pe...We study the two-stage stochastic facility location problem(2-SFLP)by proposing an LP(location problem)-rounding approximation algorithm with 2.3613 per-scenario bound for this problem,improving the previously best per-scenario bound of 2.4957.展开更多
We consider the k-level facility location problem with soft capacities （k-LFLPSC）. In the k- LFLPSC, each facility i has a soft capacity ui along with an initial opening cost fi ≥O, i.e., the capacity of facility i...We consider the k-level facility location problem with soft capacities （k-LFLPSC）. In the k- LFLPSC, each facility i has a soft capacity ui along with an initial opening cost fi ≥O, i.e., the capacity of facility i is an integer multiple of ui incurring a cost equals to the corresponding multiple of fi. We firstly propose a new bifactor （ln（1/β）/（1 -β）, 1 ＋ 2/（1 - β））-approximation algorithm for the k-level facility location problem （k-LFLP）, where β∈（0, 1） is a fixed constant. Then, we give a reduction from the k-LFLPSC to the k-LFLP. The reduction together with the above bifactor approximation algorithm for the k-LFLP imply a 5.5053-approximation algorithm for the k-LFLPSC which improves the previous 6-approximation.展开更多
In this paper, we study the dynamic facility location problem with submodular penalties （DFLPSP）. We present a combinatorial primal-dual 3-approximation algorithm for the DFLPSP.
In this paper,we consider the risk-adjusted two-stage stochastic facility location problem with penalties(RSFLPP).Using the monotonicity and positive homogeneity of the risk measure function,we present an LP-roundin...In this paper,we consider the risk-adjusted two-stage stochastic facility location problem with penalties(RSFLPP).Using the monotonicity and positive homogeneity of the risk measure function,we present an LP-rounding-based 6-approximation algorithm.展开更多
In this paper, we consider the fault-tolerant concave facility location problem （FTCFL） with uniform requirements. By investigating the structure of the FTCFL, we obtain a modified dual-fitting bifactor approximatio...In this paper, we consider the fault-tolerant concave facility location problem （FTCFL） with uniform requirements. By investigating the structure of the FTCFL, we obtain a modified dual-fitting bifactor approximation algorithm. Combining the scaling and greedy argumentation technique, the approximation factor is proved to be 1.52.展开更多
In this paper,we study a stochastic version of the fault-tolerant facility location problem.By exploiting the stochastic structure,we propose a 5-approximation algorithm which uses the LP-rounding technique based on t...In this paper,we study a stochastic version of the fault-tolerant facility location problem.By exploiting the stochastic structure,we propose a 5-approximation algorithm which uses the LP-rounding technique based on the revised optimal solution to the linear programming relaxation of the stochastic fault-tolerant facility location problem.展开更多
Determining the optimum location of facilities is critical in many fields,particularly in healthcare.This study proposes the application of a suitable location model for field hospitals during the novel coronavirus 20...Determining the optimum location of facilities is critical in many fields,particularly in healthcare.This study proposes the application of a suitable location model for field hospitals during the novel coronavirus 2019(COVID-19)pandemic.The used model is the most appropriate among the three most common location models utilized to solve healthcare problems(the set covering model,the maximal covering model,and the P-median model).The proposed nonlinear binary constrained model is a slight modification of the maximal covering model with a set of nonlinear constraints.The model is used to determine the optimum location of field hospitals for COVID-19 risk reduction.The designed mathematical model and the solution method are used to deploy field hospitals in eight governorates in Upper Egypt.In this case study,a discrete binary gaining–sharing knowledge-based optimization(DBGSK)algorithm is proposed.The DBGSK algorithm is based on how humans acquire and share knowledge throughout their life.The DBGSK algorithm mainly depends on two junior and senior binary stages.These two stages enable DBGSK to explore and exploit the search space efficiently and effectively,and thus it can solve problems in binary space.展开更多
The present study developed and tested a method to evaluate the location of aged care facilities from the viewpoint of whether they are equitably located for users,using the improved Median Share Ratio(MSR).By evaluat...The present study developed and tested a method to evaluate the location of aged care facilities from the viewpoint of whether they are equitably located for users,using the improved Median Share Ratio(MSR).By evaluating the current location of aged care facilities,it is possible to extract the districts which are short of facilities.The evaluation method was applied to Chofu and Kiyose Cities in Tokyo Metropolis,Japan,and the evaluation result of weighting and that of not weighting by elderly population were compared and discussed.Consequently,adopting the evaluation method with weighting by elderly population,it is possible to adequately examine the districts where new aged care facilities should be constructed.From this evidence,it is significant to evaluate the location of aged care facilities,using the improved MSR with weighting by elderly population in the study.展开更多
文摘The differential evolution algorithm is an evolutionary algorithm for global optimization and the un-capacitated facility location problem (UFL) is one of the classic NP-Hard problems. In this paper, combined with the specific characteristics of the UFL problem, we introduce the activation function to the algorithm for solving UFL problem and name it improved adaptive differential evolution algorithm (IADEA). Next, to improve the efficiency of the algorithm and to alleviate the problem of being stuck in a local optimum, an adaptive operator was added. To test the improvement of our algorithm, we compare the IADEA with the basic differential evolution algorithm by solving typical instances of UFL problem respectively. Moreover, to compare with other heuristic algorithm, we use the hybrid ant colony algorithm to solve the same instances. The computational results show that IADEA improves the performance of the basic DE and it outperforms the hybrid ant colony algorithm.
基金The National Natural Science Foundation of China(No.70472033).
文摘First a remanufactming logistics network is con- structed, in which the structure of both the forward logistics and the reverse logistics are of two levels and all the logistics facilities are capacitated. Both the remanufactming products and the new products can be used to meet the demands of customers. Moreover, it is assumed that homogeneous facilities can be designed together into integrated ones, based on which a mixed integer nonlinear programming （MINLP） facility location model of the remanufacturing logistics network with six types of facilities to be sited is built. Then an algorithm based on enumeration for the model is given. The feasible combinations of binary variables are searched by enumeration, and the remaining sub-problems are solved by the LP solver. Finally, the validities of the model and the algorithm are illustrated by means of an example. The result of the sensitivity analysis of parameters indicates that the integration of homogeneous facilities may influence the optimal solution of the problem to a certain degree.
基金The National Natural Science Foundation of China(No.70671021)the National Key Technology R&D Program of China during the 11th Five-Year Plan Period(No.2006BAH02A06)
文摘To smooth the correlation process from bio-virus diffusion to emergency relief response,the Gaussian plume model is used to describe the diffusion of dangerous sources,where the bio-virus concentration at any given point in affected areas can be calculated.And the toxic load rule is introduced to define the borderline of the dangerous area at different levels.Combined with this,different emergency levels of different demand points in dangerous areas are confirmed using fuzzy clustering,which allows demand points at the same emergency level to cluster in a group.Some effective emergency relief centers are chosen from the candidate hospitals which are located in different emergency level affected areas by set covering.Bioterrorism experiments which were conducted in Nanjing,Jiangsu province are simulated,and the results indicate that the novel method can be used efficiently by decision makers during an actual anti-bioterrorism relief.
基金supported by the National Natural Science Foundation of China under Grant No.11371001
文摘develop a mentation This paper considers the priority facility primal-dual 3-approximation algorithm for procedure, the authors further improve the location problem with penalties： The authors this problem. Combining with the greedy aug- previous ratio 3 to 1.8526.
文摘Facility location problem is a kind of NP-Hard combinational problem.Considering ever-changing demand sites,demand quantity and releasing cost,we formulate a model combining tabu search and FCM(fuzzy clustering method) to solve the capacitated dynamic facility location problem.Some results are achieved and they show that the proposed method is effective.
基金the National Natural Science Foundation of China(No.12101069)Innovation Foundation of BUPT for Youth(No.500421358)Ying-Chao Zhao was partially supported by the Research Grants Council of the HKSAR,China(No.UGC/FDS11/E03/21).
文摘We study the mechanism design of facility location problems.The problem is to design mechanisms to select a set of locations on which to build a set of facilities,aiming to optimize some system objective and achieve desirable properties based on the strategic agents'locations.The agents might have incentives to misreport their private locations,in order to minimize the costs(i.e.,the distance from the closest facility).We study the setting with limited locations,that is,the facilities can only be built on a given finite set of candidate locations,rather than the whole space.For locating a single facility and two facilities on a real line,we propose strategyproof mechanisms with tight approximation ratios,under the objectives of minimizing the total cost and the maximum cost.Further,we consider the problem of locating an obnoxious facility from which the agents want to stay as far away as possible,and derive tight bounds on the approximation ratio of strategyproof mechanisms.
基金partly supported by the National Science Foundation of China under Grants 51008160China Postdoctoral Science Foundation (20080430686)+1 种基金Fundamental Research Funds for the Central Universities of China (NJAU: SKZK2015005)Talent Startup Fund of College of Engineering in NJAU of China (RCQD16-01)。
文摘Emergency response activity relies on transportation networks. Emergency facility location interacts with transportation networks clearly. This review is aimed to provide a combined framework for emergency facility location in transportation networks. The article reveals emergency response activities research clusters, issues, and objectives according to keywords co-occurrence analysis. Four classes of spatial separation models in transportation networks, including distance, routing, accessibility, and travel time are introduced. The stochastic and time-dependent characteristics of travel time are described. Travel time estimation and prediction method, travel time under emergency vehicle preemption,transportation network equilibrium method, and travel time in degradable networks are demonstrated. The emergency facilities location models interact with transportation networks, involving location-routing model, location models embedded with accessibility,location models embedded with travel time, and location models employing mathematical program with equilibrium constraints are reviewed. We then point out the-state-of-art challenges: ilities-oriented, evolution landscape and sequential decision modelling, datadriven optimization approach, and machine learning-based algorithms.
基金supported by National Natural Science Foundation of China (Grant Nos. 60773185, 10401038)Program for Beijing Excellent Talents (Grant No. 20071D050150020S)
文摘In this paper,we consider the metric uncapacitated facility location game with service installation costs. Our main result is an 11-approximate cross-monotonic cost-sharing method under the assumption that the installation cost depends only on the service type.
基金supported by the National Natural Science Foundation of China under Grant Nos.60773185 and 11071268Program for Beijing Excellent Talents
文摘This paper considers a variant of the classical facility location game called the uncapacitared facility location game with penalties （UFLGWP）. Unlike the standard UFLG, each client in the UFLGWP is either assigned to an open facility or rejected by paying a penalty. The authors propose a 3-approximate cross-monotonic cost-sharing method for the UFLGWP.
基金Supported by the National Natural Science Foundation of China(No.60773185,10401038) and Program for Beijing Excellent Talents
文摘We study the soft-capacitated facility location game which is an extension of the facility location game of Pa1 and Tardos. We propose a 6-approximate cross-monotonic cost-sharing method. Numerical tests indicate that the method is effective.
基金Supported by the National Natural Science Foundation of China for Distinguished Young Scholars under Grant No. 60325206the National Natural Science Foundation of China for Major International (Regional) Joint Research Project under Grant No. 60310213the National Natural Science Foundation of China under Grant No. 60573024.
文摘Given m facilities each with an opening cost, n demands, and distance between every demand and facility, the Facility Location problem finds a solution which opens some facilities to connect every demand to an opened facility such that the total cost of the solution is minimized. The κ-Facility Location problem further requires that the number of opened facilities is at most κ, where κ is a parameter given in the instance of the problem. We consider the Facility Location problems satisfying that for every demand the ratio of the longest distance to facilities and the shortest distance to facilities is at most ω, where ω is a predefined constant. Using the local search approach with scaling technique and error control technique, for any arbitrarily small constant ε 〉 0, we give a polynomial-time approximation algorithm for the ω-constrained Facility Location problem with approximation ratio 1 ＋ √ω ＋ ε, which significantly improves the previous best known ratio （ω ＋ 1）/α for some 1 ≤ α ≤2, and a polynomial-time approximation algorithm for the ω-constrained κ- Facility Location problem with approximation ratio ω ＋ 1 ＋ ε. On the aspect of approximation hardness, we prove that unless NP C DTIME（n^O（log log n））, the ω-constrained Facility Location problem cannot be approximated within 1 ＋ln √ω 1, which slightly improves the previous best known hardness result 1.243 ＋ 0.316 ln（ω - 1）. The experimental results on the standard test instances of Facility Location problem show that our algorithm also has good performance in practice.
基金This research was supported by the National Natural Science Foundation of China(Nos.11901544 and 11801251).
文摘In the k-level facility location problem with penalties,each client will be either serviced or rejected completely.And if the client is planned to be serviced,then it must be connected to a sequence of k different kinds of facilities located in k levels of hierarchy.The total cost including the facility cost,connection cost and penalty cost will be jointly paid by all the clients.In the corresponding game of the k-level facility location problem with penalties,called the k-level facility location game with penalties,the total cost should be allocated to different clients.This work set out a cost-sharing scheme for the k-level facility location game with penalties that is cross-monotonic,competitive,and the approximate cost recovery is 6.
基金supported by National Natural Science Foundation of China (Grant No. 11371001)the Natural Sciences and Engineering Research Council of Canada (Grant No. 283106)China Scholarship Council
文摘We study the two-stage stochastic facility location problem(2-SFLP)by proposing an LP(location problem)-rounding approximation algorithm with 2.3613 per-scenario bound for this problem,improving the previously best per-scenario bound of 2.4957.
基金supported in part by Natural Science Foundation of China under Grant No.11501412supported by Natural Science Foundation of China under Grant No.11531014
文摘We consider the k-level facility location problem with soft capacities （k-LFLPSC）. In the k- LFLPSC, each facility i has a soft capacity ui along with an initial opening cost fi ≥O, i.e., the capacity of facility i is an integer multiple of ui incurring a cost equals to the corresponding multiple of fi. We firstly propose a new bifactor （ln（1/β）/（1 -β）, 1 ＋ 2/（1 - β））-approximation algorithm for the k-level facility location problem （k-LFLP）, where β∈（0, 1） is a fixed constant. Then, we give a reduction from the k-LFLPSC to the k-LFLP. The reduction together with the above bifactor approximation algorithm for the k-LFLP imply a 5.5053-approximation algorithm for the k-LFLPSC which improves the previous 6-approximation.
基金Supported in part by Hebei Province Department of Education Fund under Grant No.Z2012017the National Natural Science Foundation of China under Grant No.11371001 and 11201013
文摘In this paper, we study the dynamic facility location problem with submodular penalties （DFLPSP）. We present a combinatorial primal-dual 3-approximation algorithm for the DFLPSP.
基金This work was supported by Scientific Research Common Program of Beijing Municipal Commission of Education(No.KM201210005033)and China Scholarship CouncilThe authors would like to thank the two anonymous referees for many helpful suggestions.
文摘In this paper,we consider the risk-adjusted two-stage stochastic facility location problem with penalties(RSFLPP).Using the monotonicity and positive homogeneity of the risk measure function,we present an LP-rounding-based 6-approximation algorithm.
基金Supported by the National Natural Science Foundation of China (No. 60773185, 11071268, 10871144)Beijing Natural Science Foundation (No. 1102001)
文摘In this paper, we consider the fault-tolerant concave facility location problem （FTCFL） with uniform requirements. By investigating the structure of the FTCFL, we obtain a modified dual-fitting bifactor approximation algorithm. Combining the scaling and greedy argumentation technique, the approximation factor is proved to be 1.52.
基金C.Wu was supported by National Natural Science Foundation of China(Grant No.11071268)D.Xu was supported by National Natural Science Foundation of China(Grant No.11371001)+2 种基金Scientific Research Common Program of Beijing Municipal Commission of Education(Grant No.KM201210005033)China Scholarship Council.J.Shu was supported by National Natural Science Foundation of China(Grant Nos.70801014,71171047,and 71222103)The authors would like to thank the two anonymous referees for many helpful suggestions.
文摘In this paper,we study a stochastic version of the fault-tolerant facility location problem.By exploiting the stochastic structure,we propose a 5-approximation algorithm which uses the LP-rounding technique based on the revised optimal solution to the linear programming relaxation of the stochastic fault-tolerant facility location problem.
基金funded by Deanship of Scientific Research,King Saud University,through the Vice Deanship of Scientific Research.
文摘Determining the optimum location of facilities is critical in many fields,particularly in healthcare.This study proposes the application of a suitable location model for field hospitals during the novel coronavirus 2019(COVID-19)pandemic.The used model is the most appropriate among the three most common location models utilized to solve healthcare problems(the set covering model,the maximal covering model,and the P-median model).The proposed nonlinear binary constrained model is a slight modification of the maximal covering model with a set of nonlinear constraints.The model is used to determine the optimum location of field hospitals for COVID-19 risk reduction.The designed mathematical model and the solution method are used to deploy field hospitals in eight governorates in Upper Egypt.In this case study,a discrete binary gaining–sharing knowledge-based optimization(DBGSK)algorithm is proposed.The DBGSK algorithm is based on how humans acquire and share knowledge throughout their life.The DBGSK algorithm mainly depends on two junior and senior binary stages.These two stages enable DBGSK to explore and exploit the search space efficiently and effectively,and thus it can solve problems in binary space.
文摘The present study developed and tested a method to evaluate the location of aged care facilities from the viewpoint of whether they are equitably located for users,using the improved Median Share Ratio(MSR).By evaluating the current location of aged care facilities,it is possible to extract the districts which are short of facilities.The evaluation method was applied to Chofu and Kiyose Cities in Tokyo Metropolis,Japan,and the evaluation result of weighting and that of not weighting by elderly population were compared and discussed.Consequently,adopting the evaluation method with weighting by elderly population,it is possible to adequately examine the districts where new aged care facilities should be constructed.From this evidence,it is significant to evaluate the location of aged care facilities,using the improved MSR with weighting by elderly population in the study.
