scholarly journals Multimodal Capacitated Hub Location Problems with Multi-Commodities: An Application in Freight Transport

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Alan Osorio-Mora ◽  
Francisco Núñez-Cerda ◽  
Gustavo Gatica ◽  
Rodrigo Linfati
Keyword(s):  
Latin American ◽  
Location Problems ◽  
Transport Cost ◽  
Mixed Integer ◽  
Hub Location ◽  
Proposed Model ◽  
Multimodal Transport ◽  
Two Factors ◽  
Commercial Solver

Hub location problems (HLPs) support decision making on multimodal transport strategic planning. It is related to the location of hubs and the allocation of origin/destination (O/D) flow in a system. Classical formulations assume that these flows are predefined paths and direct delivery is not available. This applied research presents a mixed integer linear programming (MILP) model for a capacitated multimodal, multi-commodity HLP. Furthermore, an application on the export process in a Latin American country is detailed. The new proposed model, unlike the traditional HLP, allows direct shipment, and its O/D flows are part of the decision model. Situations with up to 100 nodes, six products, and two transport modes are used, working with initial and projected flows. All instances can be solved optimally using the commercial solver, Gurobi 7.5.0, in computational times less than a minute. Results indicate that only one hub is profitable for the case study, both for the initial and projected scenarios. The installation of a hub generates transport savings over 1% per year. Two factors affect the location decision: low concentration and distance between the hubs and destinations. Long distances involve an exhaustive use of trains instead of trucks, which leads to lower transport cost per unit.

An Assessment of the Belt and Road Performance

2019 ◽  
pp. 108-127
Author(s):  
Sedat Baştuğ ◽  
Turgay Battal
Keyword(s):  
Cost Model ◽  
Volume Ratio ◽  
Transport Cost ◽  
Primary Methods ◽  
Original Analysis ◽  
Multimodal Transport ◽  
Belt And Road ◽  
The Cost ◽  
The Belt And Road

The aim of the chapter is to propose a methodology to illustrate the cost and time components of door-to-door movement by One Belt and One Road (OBOR) and traditional routes alongside with modes. The study is concentrated on a case study and uses established multimodal transport cost model as a research framework. Interviews with industry practitioners and observation from primary methods of data collection. The use of multimodal transport cost model is common in the containerized cargoes. Hence, this study provides an original analysis for OBOR initiative. The volumes of OBOR shipments are large, with a high value-to-volume ratio. The research initially confirms that multimodal transport alternatives and modal combinations may successfully be applied and assess the performance of OBOR initiative.

scholarly journals OPTIMIZING THE CONTAINER TRUCK PATHS WITH UNCERTAIN TRAVEL TIME IN CONTAINER PORTS

Transport ◽  
2021 ◽  
Vol 36 (6) ◽  
pp. 444-462
Author(s):  
Jiaming Liu ◽  
Bin Yu ◽  
Wenxuan Shan ◽  
Baozhen Yao ◽  
Yao Sun
Keyword(s):  
Travel Time ◽  
Shortest Path ◽  
Programming Model ◽  
Mixed Integer ◽  
A Algorithm ◽  
Shuffled Complex Evolution ◽  
Proposed Model ◽  
Container Ports ◽  
Yard Template

The yard template problem in container ports determines the assignment of space to store containers for the vessels, which could impact container truck paths. Actually, the travel time of container truck paths is uncertain. This paper considers the uncertainty from two perspectives: (1) the yard congestion in the context of yard truck interruptions, (2) the correlation among adjacent road sections (links). A mixed-integer programming model is proposed to minimize the travel time of container trucks. The reliable shortest path, which takes the correlation among links into account is firstly discussed. To settle the problem, a Shuffled Complex Evolution Approach (SCE-UA) algorithm is designed to work out the assignment of yard template, and the A* algorithm is presented to find the reliable shortest path according to the port operator’s attitude. In our case study, one yard in Dalian (China) container port is chosen to test the applicability of the model. The result shows the proposed model can save 9% of the travel time of container trucks, compared with the model without considering the correlation among adjacent links.

scholarly journals Transfer Coordination for Metro Networks during the Start- or End-of-Service Period

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Liqiao Ning ◽  
Peng Zhao ◽  
Wenkai Xu ◽  
Ke Qiao
Keyword(s):  
Integer Programming ◽  
Adverse Effects ◽  
Waiting Time ◽  
Programming Model ◽  
Mixed Integer ◽  
Service Period ◽  
Proposed Model ◽  
Transfer Success ◽  
Metro Networks

When travelling via metro networks during the start- or end-of-service period, transferring passengers may suffer a transfer failure. Accordingly, the synchronization timetabling problem necessitates consideration of transfer waiting time and transfer availability with respect to the first or last train. Hence, transfer train index (TTI) is formulated to identify the transfer train and calculate the transfer waiting time. Furthermore, two types of connection indexes, the last connection train index (LCTI) and the first connection train index (FCTI), are devised to distinguish transfer failure from transfer success, and the penalty constraints are implemented together to reflect the adverse effects of transfer failure. Then, a mixed integer programming model is developed to concurrently reduce transfer waiting time and improve transfer availability, which can be solved by CPLEX. Finally, a case study on Beijing metro network is made to verify the method. Experimental results show that our proposed model can yield synchronization solutions with significant reductions in both the average transfer waiting time and the proportion of transfer failure passengers.

scholarly journals A Bilevel Multiobjective Optimisation Approach for Solving the Evacuation Location Assignment Problem

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Ahmed W. A. Hammad
Keyword(s):  
Assignment Problem ◽  
Programming Model ◽  
Decision Makers ◽  
Mixed Integer ◽  
Multiobjective Optimisation ◽  
Proposed Model ◽  
Level Problem ◽  
Location Assignment ◽  
Optimisation Model

In this paper, a bilevel multiobjective optimisation model is proposed to solve the evacuation location assignment problem. The model incorporates the two decision-makers’ spaces, namely, urban planners and evacuees. In order to solve the proposed problem, it is first reformulated into a single-level problem using the Karush–Kuhn–Tucker conditions. Next, the problem is linearised into a mixed-integer linear programming model and solved using an off-the-shelf solver. A case study is examined to showcase the applicability of the proposed model, which is solved using single-objective and multiobjective lexicographic optimisation approaches. The model provides planners with an ability to determine the best locations for placement of shelters in such a way that the evacuees’ traffic assignment on the existing network is optimised.

scholarly journals Impact of Wind Power Generation on System Operation and Costs

2014 ◽  
Vol 8 (1) ◽  
pp. 580-588
Author(s):  
Wang Fei ◽  
Pan Wenxia ◽  
Quan Rui
Keyword(s):  
Wind Power ◽  
Power Plants ◽  
Unit Commitment ◽  
Mixed Integer ◽  
System Operation ◽  
Spinning Reserve ◽  
Proposed Model ◽  
Integer Problem ◽  
The Impact

In this paper, a deterministic security-constrained unit commitment (SCUC) model is deployed in order to optimize generation output and allocation for spinning reserve considering different wind power dispatch modes. In this model, the scheduling of power plants takes into account a simultaneous clearing of power, reserve capacity requirement and CO2 emission and so on. Spinning reserve is modelled as an exogenous parameter which represents load uncertainty and wind power uncertainty. Special attention in the study is given to determine the impact of different dispatch modes with wind power and different levels of spinning reserve requirement on system operation and costs. The proposed model can be formulated as a mixed-integer problem (MIP) and solved in GAMS by using the CPLEX optimizer. The model is applied to a wind-fired intensive power system for three case studies. The results include the optimal spinning reserve and generator output of each generator, CO2 emission cost and cost of wind power for each case study. The results show that taking wind power as a control option can improves system operation and costs if wind generation and traditional sources generation are coordinated properly.

scholarly journals OPTIMISING THE ANALYSIS STAGE IN THE INTERNATIONALISATION OF MANUFACTURING OPERATIONS

2021 ◽  
Vol 32 (2) ◽  
Author(s):  
Fabio Comer ◽  
Josefa Mula ◽  
Manuel Díaz-Madroñero ◽  
Hanzel Grillo
Keyword(s):  
Decision Making ◽  
Programming Model ◽  
Mixed Integer ◽  
Strategic Decisions ◽  
Manufacturing Operations ◽  
Proposed Model ◽  
Production And Distribution ◽  
Global Supplier ◽  
Near Future

The internationalisation of the manufacturing operations process includes decision-making about new facility implementation (NFI) and global supplier network development (GSND), whose first step is to analyse the situation of a company and its environment. The purpose of this paper is to investigate the optimal design of a manufacturing production and distribution network for global small- and medium-sized enterprises (SMEs). This research uses a mixed-integer linear programming (MILP) model to support decision-making in the analysis stage of the internationalisation of manufacturing operations for global SMEs. A real- world case study is presented to illustrate the application of the proposed model. Different scenarios were evaluated not only to identify the strengths and limitations of the mathematical programming model, but to also provide support for the next strategic decisions that the examined company has to make in the near future.

scholarly journals A Multi-objective MILP Model Proposed to Optimize a Supply Chain Network for Microalgae-based Biofuels and Co-products: A Case Study in Iran

2021 ◽  
Author(s):  
Mohammad Ehsan Zerafati ◽  
Ali Bozorgi-Amiri ◽  
Amir-Mohammad Golmohammadi ◽  
Fariborz Jolai
Keyword(s):  
Supply Chain ◽  
Objective Function ◽  
Environmental Impacts ◽  
Deterministic Model ◽  
Mixed Integer ◽  
Supply Chain Network ◽  
Multi Objective ◽  
Proposed Model ◽  
Milp Model

Abstract Recently, due to the efficiency of cultivating microalgae, researchers and investors have paid considerable attention to the production of different biofuel products that are environmentally friendly. In this study, a two-stage deterministic model is proposed to design a microalgae-based biofuels and co-products supply chain network (MBCSCN). In the first stage, the appropriate locations for the cultivation of microalgae are identified through the analytical hierarchy process (AHP). In the second stage, a deterministic mathematical mixed integer linear programing (MILP) model is developed for a period of five years based on the criteria of economic and environmental impacts. The economic objective function maximizes the overall profit, while the environmental impacts objective function seeks to minimize the consumed fossil fuel throughout the supply chain. Then, a multi-objective MILP optimization problem is solved using the ε-constraint method. The proposed model is evaluated through a case study in Iran. It has helped to identify appropriate locations for the cultivation of microalgae and to specify the required quantity of feedstock, the species of microalgae, the required technology, and the transportation modes in each step of the supply chain.

scholarly journals A Practical Traffic Assignment Model for Multimodal Transport System Considering Low-Mobility Groups

Mathematics ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 351 ◽  
Author(s):  
Tao Zhang ◽  
Yang Yang ◽  
Gang Cheng ◽  
Minjie Jin
Keyword(s):  
Transport System ◽  
Traffic Assignment ◽  
Transportation Network ◽  
Travel Costs ◽  
Assignment Model ◽  
Proposed Model ◽  
Multimodal Transport ◽  
Logit Function ◽  
Private Car

In this study, we created a practical traffic assignment model for a multimodal transport system considering low-mobility groups with the aim of providing the foundation of transportation network design for low-mobility individuals. First, the route choice equilibrium for walking, non-vehicle, and private car modes is described using the logit function, which is formulated as a variational inequality problem considering different low-mobility groups. Then, the practicalities related to travel times at intersections, traffic barricades between different lanes, and fuel fees of private cars are integrated to design a generalized travel cost function. Last, the method of successive weight averages is used to solve the proposed model. The model and its solution are verified based on a real case study of the city of Wenling in China. The sensitivity of adjustment parameters related to travel costs are analyzed, the practicality of the proposed model is explored, and the results of traffic assignment for different low-mobility groups are discussed.

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