Transportation
Sarow Saeedi; Omid Poursabzi; Zaniar Ardalan; Sajad Karimi
Abstract
Hub location problems (HLP) have multiple applications in logistic systems, the airways industry, supply chain network design, and telecommunication. In the HLP, the selected nodes as hubs perform the principal role in processing the inflow arising from other nodes. So, congestion would be inevitable ...
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Hub location problems (HLP) have multiple applications in logistic systems, the airways industry, supply chain network design, and telecommunication. In the HLP, the selected nodes as hubs perform the principal role in processing the inflow arising from other nodes. So, congestion would be inevitable at hub nodes. This paper considers a p-hub median problem with multiple hub node servers delivering service at variable rates. Since the service rates are limited and variable, a queue is formed at each hub server. To tackle this problem, we developed a mixed-integer linear programming model that optimizes the selected hub nodes to reduce congestion under an allowable defined queue length at each server and minimize the total costs of the model, including transportation and hub establishment costs. We utilized the Civil Aeronautics Board (CAB) dataset containing 25 USA cities, which is a valuable source for designing numerical examples in the HLP, to prove the model's efficiency. The results obtained from the designed sample problems show that strategic decisions on defining the number of hubs and maximum acceptable queue length at each hub server will significantly impact the hub location network design.
Transportation
Vasilis Apostolopoulos; George Kasselouris
Abstract
One of the main topics with increasing interest in freight transport and logistics is developing efficient and sustainable supply chain strategies that best cover customer demands and expectations as well as identify considerable cost savings and emission reductions. This study focuses on the evaluation ...
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One of the main topics with increasing interest in freight transport and logistics is developing efficient and sustainable supply chain strategies that best cover customer demands and expectations as well as identify considerable cost savings and emission reductions. This study focuses on the evaluation of the potential of a logistics centre for consolidating and delivering goods at urban level, based on economic, social and environmental aspects, by performing both GIS simulation and SWOT analysis, while considering key criteria of transport management, infrastructure and fleet attributes as well as logistics and market features in the Attica region of Greece. The case refers to the largest Logistics Centre of Greece, located at Thriasio, offering door-to door services to the main industrial areas of the region. The approach followed, consists of two core elements: a) a specific model of a last-mile delivery network in GIS environment, towards simulating and solving the Vehicle Routing Problem (VRP) as well as b) a strategic assessment of the foreseen logistics activities through the SWOT business tool. For a transport operator with 5 vehicles, an operational distance-related cost of €1.8-1.9 per pallet was estimated. Results also show the lower environmental impact of larger vehicles due to transport pooling.
Transportation
Mohamad Ebrahim Tayebi Araghi; Fariborz Jolai; Reza Tavakkoli-Moghaddam; Mohammad Molana
Abstract
The Location Routing Problem (LRP), Automatic Guided Vehicle (AGV), and Uncertainty Planner Facility (UPF) in Facility Location Problems (FLP) have been critical. This research proposed the role of LRP in Intelligence AGV Location–Routing Problem (IALRP) and energy-consuming impact in CMS. The ...
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The Location Routing Problem (LRP), Automatic Guided Vehicle (AGV), and Uncertainty Planner Facility (UPF) in Facility Location Problems (FLP) have been critical. This research proposed the role of LRP in Intelligence AGV Location–Routing Problem (IALRP) and energy-consuming impact in CMS. The goal of problem minimization dispatching opening cost and the cost of AGV trucking. We set up multi-objective programming. To solve the model, we utilized and investigate the Imperialist Competitor Algorithm (ICA) with Variable Neighborhood Search (VNS). It is shown that the ICAVNS algorithm is high quality effects for the integrated LRP in AGVs and comparison, with the last researches, the sensitivity analysis, and numerical examples imply the validity and good convexity of the purposed model according to the cost minimization.
Transportation
Azra Ghobadi; Reza Tavakkoli Moghadam; Mohammad Fallah; Hamed Kazemipoor
Abstract
The use of an Electric Vehicle (EV), particularly in different operations of goods distribution is a solution for salvaging the crowded cities of the world from air and noise pollutions as well as Green House Gas (GHG) emission. This paper presents a Multi-Depot Electric Vehicle Routing Problem (MD-EVRP) ...
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The use of an Electric Vehicle (EV), particularly in different operations of goods distribution is a solution for salvaging the crowded cities of the world from air and noise pollutions as well as Green House Gas (GHG) emission. This paper presents a Multi-Depot Electric Vehicle Routing Problem (MD-EVRP) with recharging stations by considering the expected penalty of fuzzy time windows in pickup/delivery. Since the MD-EVRP with Fuzzy Time Windows and Pickup/Delivery (MD-EVRP-FTW-PD) constraints is an NP-hard problem, three meta-heuristics (i.e., Simulated Annealing (SA), Variable Neighborhood Search (VNS) and a hybrid of SA and VNS (VNS-SA)) are used to solve such a hard problem. The parameters of these algorithms are measured by the Taguchi experimental design method. The proposed hybrid VNS-SA algorithm is more efficient in comparison with other algorithms.
Transportation
kolsoom Ahmadi
Abstract
We present a modification of three existing methods for finding a basic feasible solution for capacitated transportation problem. To obtain an optimal solution, the simplex algorithm for bounded variables is applied. Special properties of transportation problem help us to operate ...
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We present a modification of three existing methods for finding a basic feasible solution for capacitated transportation problem. To obtain an optimal solution, the simplex algorithm for bounded variables is applied. Special properties of transportation problem help us to operate each step of simplex algorithm directly on the transportation tableau. At last, numerical examples are represented to illustrate our method.
Transportation
Adetayo Olaniyi Adeniran; Sidiq Okwudili Ben
Abstract
For planning process, this study examined the econometric model of domestic air travel in Nigeria vis-à-vis some selected economic variables. Furthermore, quantitative (inferential) statistics has used which relies on data obtained from relevant government institutions in Nigeria. Also the model ...
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For planning process, this study examined the econometric model of domestic air travel in Nigeria vis-à-vis some selected economic variables. Furthermore, quantitative (inferential) statistics has used which relies on data obtained from relevant government institutions in Nigeria. Also the model was estimated using Ordinary Least Square (OLS) regression. From the estimate; the predictor variables constant revealed that Domestic Passenger demand is a negative value which signifies that the predictors (economic variables) cannot give true estimate of the domestic airline forecast regardless of the positive regression coefficient for the predictors. On the other side, Domestic Passenger demand positively contributes to economic indicators. When validating the model estimate, test of significance revealed that there is no statistically significant relationship between the variables. Based on the insignificance, the model estimate cannot give a good forecast. Test for multicollinearity revealed that the coefficient of determination (R2) is 0.805 which is greater than 0.8. This signifies that there is a problem of multicollinearity. Based on this problem, the model estimate cannot give a good forecast. Goodness of fit test revealed that 80.5% of the dependent variable (Domestic Passenger demand) can be explained by the independent variables. The regression value signifies that the model can give a true forecast. Finally, based on the issues of validation, it is therefore concluded that the model cannot give a true forecast, hence economic indicators contributes little or no to air transport demand but rather air transport demand contributes significantly to economic indicators.