Based on the characteristics of the air alliance environment saving transport mileage,the hub location problem of the air cargo network was studied.First,the air alliance selection probability model was introduced to ...Based on the characteristics of the air alliance environment saving transport mileage,the hub location problem of the air cargo network was studied.First,the air alliance selection probability model was introduced to determine the alliance self-operation or outsourcing probability in different segments.Then,according to the location center rule,with the goal of minimizing the total cost,the hub location model was built.The improved immune chaos genetic algorithm was used to solve this model.The results show that the improved algorithm has stronger convergence and better effect than the immune genetic algorithm.When the number of hubs increases,the fixed cost increases,but the transportation cost decreases.The greater the discount factor,the fixed cost,and the self operating cost sharing coefficient,the higher the total network cost.The airline which joins the air alliance can greatly reduce the operating cost of airlines.Therefore,airlines should consider joining the alliance.展开更多
The key factors for designing a successful hub-and-spoke network are to determine the optimal number of hubs, to properly locate hubs, and to allocate the non-hubs to the hubs. This paper proposed a hybrid heuristic b...The key factors for designing a successful hub-and-spoke network are to determine the optimal number of hubs, to properly locate hubs, and to allocate the non-hubs to the hubs. This paper proposed a hybrid heuristic based on genetic algorithm （GA） to resolve the uncapacitated single allocation hub location problem with fixed cost （ USAHLPFC）, according to the upper bound of the ratio of the number of hubs to the number of nodes. Computational experiments were conducted using the Civil Aeronautics Board （CAB） data set. Results indicate that, applying the proposed heuristic, one can obtain the optimal solutions for all small-scaled problems very efficiently. A comparison between the proposed hybrid heuristic method and the GA presented by Topcuoglu et al. shows that the former outperforms the latter when the discount factor α is less.展开更多
An optimization model for the regional comprehensive freight hub location problem was built up from the viewpoint of the minimum cost of freight system. The construction method for regional comprehensive intermodal fr...An optimization model for the regional comprehensive freight hub location problem was built up from the viewpoint of the minimum cost of freight system. The construction method for regional comprehensive intermodal freight network was put forward, and three constraints of the reasonable and feasible path of the intermodal transport, i. e. , reasonable sequence, reasonable freight distance, and reasonable conversion times, were proposed according to the general concepts of the intermodal freight. Then the method for solving the model was given based on the super network and genetic algorithm. Finally, the model and the solution were verified by case study.展开更多
As global air transportation as well as supply chains face unprecedented challenges,optimizing hub locations is crucial for enhancing efficiency,reducing costs,and mitigating environmental impacts.This paper reviews t...As global air transportation as well as supply chains face unprecedented challenges,optimizing hub locations is crucial for enhancing efficiency,reducing costs,and mitigating environmental impacts.This paper reviews the state-of-the-art in hub location problems,with a particular focus on air transportation,driven by the increasing complexity and importance of networks in today’s interconnected world.Our review offers two major contributions:a meta-review of existing surveys to synthesize current knowledge and identify gaps,and the proposal of ten critical research challenges encapsulated in the acronym DISRUPTIVE.These challenges include the need for high-quality datasets,deeper analytical insights,sustainability considerations,robustness against disruptions,addressing uncertainty,leveraging parallelization techniques,incorporating temporal dynamics,embracing interdisciplinary approaches,designing versatile hubs,and exploring emerging transportation modes.By addressing these challenges,researchers can drive innovation in hub location problems,paving the way for more resilient and efficient logistical networks that meet the demands of a rapidly evolving global landscape.展开更多
This paper discusses the fixed-hub single allocation problem(FHSAP).In this problem,a network consists of hub nodes and terminal nodes.Hubs are fixed and fully connected;each terminal node is assigned to a single hub ...This paper discusses the fixed-hub single allocation problem(FHSAP).In this problem,a network consists of hub nodes and terminal nodes.Hubs are fixed and fully connected;each terminal node is assigned to a single hub which routes all its traffic.The goal is to minimize the cost of routing the traffic in the network.In this paper,we propose a new linear programming(LP)relaxation for this problem by incorporating a set of validity constraints into the classical formulations by Ernst and Krishnamoorthy(Locat Sci 4:139–154,Ann Op Res 86:141–159).A geometric rounding algorithm is then used to obtain an integral solution from the fractional solution.We show that by incorporating the validity constraints,the strengthened LP often provides much tighter upper bounds than the previous methods with a little more computational effort and the solution obtained often has a much smaller gap with the optimal solution.We also formulate a robust version of the FHSAP and show that it can guard against data uncertainty with little costs.展开更多
Urban air mobility(UAM)extends urban transportation to low-altitude airspace using electric vertical take-off and landing(eVTOL)vehicle to reduce traffic congestion.The vertical take-off and landing(VTOL)site connecti...Urban air mobility(UAM)extends urban transportation to low-altitude airspace using electric vertical take-off and landing(eVTOL)vehicle to reduce traffic congestion.The vertical take-off and landing(VTOL)site connecting ground and air transport is the critical infrastructure of the UAM.Determining its locations is essential for the design and operation of the air route.This study focuses on the problem of the location of the VTOL site,using Shenzhen as the study area,and establishes an integer programming model with the objective of maximizing travel cost savings to identify the optimal locations of the VTOL sites.This study is different from existing ones in that it explicitly considers the three-dimensional spatial availability of VTOL sites.Geographic information system(GIS)tools are used to identify locations that satisfy two-dimensional(2D)planar availability,and an obstacle assessment model of the approach/departure and transitional surfaces of the VTOL site is built to further screen the locations.The selected potential sites are used as input to the integer programming model,ensuring that the locations identified to establish the VTOL site are optimal.The impact of the number of VTOL sites,the user's transfer time at the VTOL sites,and the eVTOL pricing on the model solution is also discussed.Although this study uses Shenzhen as a research object,the proposed methodology is generalized and applicable to any other city or region,providing recommendations and references for initial planning and related operations of the UAM in selected areas.展开更多
Beijing Global Trade Center(GTC)enjoys a privileged location on the southeast of Anzhen Bridge,which is surrounded by business areas around CBD,Lufthansa Center,Financial Street,Zhongguancun(China’s Silicone Valley)a...Beijing Global Trade Center(GTC)enjoys a privileged location on the southeast of Anzhen Bridge,which is surrounded by business areas around CBD,Lufthansa Center,Financial Street,Zhongguancun(China’s Silicone Valley)and the Asian Games Center.It brings together many resource advantages and carries unlimited business opportunities.As an integration of six grade-A intelligent office buildings,one international five-star hotel and serviced apartment buildings,GTC bears multiple business functions and its international standards are devoted to the service of international business elites.The six- office buildings are finely divided and majestically designed.All the six buildings are covered by exterior glass,which is Pilkington Arctic Blue imported from展开更多
基金The National Social Science Foundation of China(No.17XGL013)。
文摘Based on the characteristics of the air alliance environment saving transport mileage,the hub location problem of the air cargo network was studied.First,the air alliance selection probability model was introduced to determine the alliance self-operation or outsourcing probability in different segments.Then,according to the location center rule,with the goal of minimizing the total cost,the hub location model was built.The improved immune chaos genetic algorithm was used to solve this model.The results show that the improved algorithm has stronger convergence and better effect than the immune genetic algorithm.When the number of hubs increases,the fixed cost increases,but the transportation cost decreases.The greater the discount factor,the fixed cost,and the self operating cost sharing coefficient,the higher the total network cost.The airline which joins the air alliance can greatly reduce the operating cost of airlines.Therefore,airlines should consider joining the alliance.
文摘The key factors for designing a successful hub-and-spoke network are to determine the optimal number of hubs, to properly locate hubs, and to allocate the non-hubs to the hubs. This paper proposed a hybrid heuristic based on genetic algorithm （GA） to resolve the uncapacitated single allocation hub location problem with fixed cost （ USAHLPFC）, according to the upper bound of the ratio of the number of hubs to the number of nodes. Computational experiments were conducted using the Civil Aeronautics Board （CAB） data set. Results indicate that, applying the proposed heuristic, one can obtain the optimal solutions for all small-scaled problems very efficiently. A comparison between the proposed hybrid heuristic method and the GA presented by Topcuoglu et al. shows that the former outperforms the latter when the discount factor α is less.
基金The National Natural Science Foundation of China (No.50708020)Provincial Natural Science Fund of Jiangsu (BK2007566)
文摘An optimization model for the regional comprehensive freight hub location problem was built up from the viewpoint of the minimum cost of freight system. The construction method for regional comprehensive intermodal freight network was put forward, and three constraints of the reasonable and feasible path of the intermodal transport, i. e. , reasonable sequence, reasonable freight distance, and reasonable conversion times, were proposed according to the general concepts of the intermodal freight. Then the method for solving the model was given based on the super network and genetic algorithm. Finally, the model and the solution were verified by case study.
基金supported by the National Natural Science Foundation of China(Grant No.U2233214).
文摘As global air transportation as well as supply chains face unprecedented challenges,optimizing hub locations is crucial for enhancing efficiency,reducing costs,and mitigating environmental impacts.This paper reviews the state-of-the-art in hub location problems,with a particular focus on air transportation,driven by the increasing complexity and importance of networks in today’s interconnected world.Our review offers two major contributions:a meta-review of existing surveys to synthesize current knowledge and identify gaps,and the proposal of ten critical research challenges encapsulated in the acronym DISRUPTIVE.These challenges include the need for high-quality datasets,deeper analytical insights,sustainability considerations,robustness against disruptions,addressing uncertainty,leveraging parallelization techniques,incorporating temporal dynamics,embracing interdisciplinary approaches,designing versatile hubs,and exploring emerging transportation modes.By addressing these challenges,researchers can drive innovation in hub location problems,paving the way for more resilient and efficient logistical networks that meet the demands of a rapidly evolving global landscape.
基金the National Natural Science Foundation of China(No.11471205).
文摘This paper discusses the fixed-hub single allocation problem(FHSAP).In this problem,a network consists of hub nodes and terminal nodes.Hubs are fixed and fully connected;each terminal node is assigned to a single hub which routes all its traffic.The goal is to minimize the cost of routing the traffic in the network.In this paper,we propose a new linear programming(LP)relaxation for this problem by incorporating a set of validity constraints into the classical formulations by Ernst and Krishnamoorthy(Locat Sci 4:139–154,Ann Op Res 86:141–159).A geometric rounding algorithm is then used to obtain an integral solution from the fractional solution.We show that by incorporating the validity constraints,the strengthened LP often provides much tighter upper bounds than the previous methods with a little more computational effort and the solution obtained often has a much smaller gap with the optimal solution.We also formulate a robust version of the FHSAP and show that it can guard against data uncertainty with little costs.
基金National Natural Science Foundation of China(Grant Nos.U2033203 and 52272333)Fundamental Research Funds for Central Universities of Nanjing University of Aeronautics and Astronautics(Grant No.3082022NS2022067).
文摘Urban air mobility(UAM)extends urban transportation to low-altitude airspace using electric vertical take-off and landing(eVTOL)vehicle to reduce traffic congestion.The vertical take-off and landing(VTOL)site connecting ground and air transport is the critical infrastructure of the UAM.Determining its locations is essential for the design and operation of the air route.This study focuses on the problem of the location of the VTOL site,using Shenzhen as the study area,and establishes an integer programming model with the objective of maximizing travel cost savings to identify the optimal locations of the VTOL sites.This study is different from existing ones in that it explicitly considers the three-dimensional spatial availability of VTOL sites.Geographic information system(GIS)tools are used to identify locations that satisfy two-dimensional(2D)planar availability,and an obstacle assessment model of the approach/departure and transitional surfaces of the VTOL site is built to further screen the locations.The selected potential sites are used as input to the integer programming model,ensuring that the locations identified to establish the VTOL site are optimal.The impact of the number of VTOL sites,the user's transfer time at the VTOL sites,and the eVTOL pricing on the model solution is also discussed.Although this study uses Shenzhen as a research object,the proposed methodology is generalized and applicable to any other city or region,providing recommendations and references for initial planning and related operations of the UAM in selected areas.
文摘Beijing Global Trade Center(GTC)enjoys a privileged location on the southeast of Anzhen Bridge,which is surrounded by business areas around CBD,Lufthansa Center,Financial Street,Zhongguancun(China’s Silicone Valley)and the Asian Games Center.It brings together many resource advantages and carries unlimited business opportunities.As an integration of six grade-A intelligent office buildings,one international five-star hotel and serviced apartment buildings,GTC bears multiple business functions and its international standards are devoted to the service of international business elites.The six- office buildings are finely divided and majestically designed.All the six buildings are covered by exterior glass,which is Pilkington Arctic Blue imported from
