The Experts below are selected from a list of 14793 Experts worldwide ranked by ideXlab platform
Teodor Gabriel Crainic - One of the best experts on this subject based on the ideXlab platform.
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Designing the master schedule for demand-adaptive transit systems
2020Co-Authors: Teodor Gabriel Crainic, Fausto Errico, Federico Malucelli, Maddalena NonatoAbstract:Abstract Demand-Adaptive Systems (DAS) display features of both traditional fixed-line bus services and purely on-demand systems such as dial-a-ride, that is they offer demand-responsive services within the framework of traditional scheduled bus transportation. A DAS bus line serves, on one hand, a given set of compulsory stops according to a predefined schedule specifying the time windows associated with each, providing the traditional use of the transit line, without requiring any reservation. On the other hand, passengers may also issue requests for transportation between two desired, optional, stops, which induces detours in the vehicle routes. The design of a DAS line is a complex Planning operation that requires to determine not only its design in terms of selecting the compulsory stops, but also its master schedule in terms of the time windows associated with the compulsory stops. Designing a DAS thus combines elements of strategic and Tactical Planning. In this paper we focus on determining a master-schedule for a single DAS line. We propose a mathematical description and a solution framework based on the estimation of a number of statistical parameters of the demand and the DAS line service. Results of numerical experiments are also given and analyzed
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service network design in freight transportation
European Journal of Operational Research, 2000Co-Authors: Teodor Gabriel CrainicAbstract:Abstract Tactical Planning of operations is comprised of a set of interrelated decisions that aim to ensure an optimal allocation and utilization of resources to achieve the economic and customer service goals of the company. Tactical Planning is particularly vital for intercity freight carriers that make intensive use of consolidation operations. Railways and less-than-truckload motor carriers are typical examples of such systems. Service Network Design is increasingly used to designate the main Tactical issues for this type of carriers: selection and scheduling of services, specification of terminal operations, routing of freight. The corresponding models usually take the form of network design formulations that are difficult to solve, except in the simplest of cases. The paper presents a state-of-the-art review of service network design modelling efforts and mathematical programming developments for network design. A new classification of service network design problems and formulations is also introduced.
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dual ascent procedures for multicommodity location allocation problems with balancing requirements
Transportation Science, 1993Co-Authors: Teodor Gabriel Crainic, Louis DelormeAbstract:The multicommodity location-allocation problem with balancing requirements is related to one of the major logistics issues faced by distribution and transportation firms: the management of the fleet of vehicles over a medium to long-term Planning horizon. We present a dual-ascent approach for this formulation which may be used either to obtain a good heuristic solution, or to compare sharp bounds in a branch-and-bound scheme. We present and compare two variants of this approach, and analyze their performances both on a large number of randomly generated problems and on a large-scale application to the strategic/Tactical Planning of the land operations of an international maritime container shipping firm. Our results demonstrate that a dual-ascent approach is highly effective in this context.
Daniele Vigo - One of the best experts on this subject based on the ideXlab platform.
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a service network design model for multimodal municipal solid waste transport
European Journal of Operational Research, 2016Co-Authors: Dirk Inghels, Wout Dullaert, Daniele VigoAbstract:A modal shift from road transport towards inland water or rail transport could reduce the total Green House Gas emissions and societal impact associated with Municipal Solid Waste management. However, this shift will take place only if demonstrated to be at least cost-neutral for the decision makers. In this paper we examine the feasibility of using multimodal truck and inland water transport, instead of truck transport, for shipping separated household waste in bulk from collection centres to waste treatment facilities. We present a dynamic Tactical Planning model that minimises the sum of transportation costs, external environmental and societal costs. The Municipal Solid Waste Service Network Design Problem allocates Municipal Solid Waste volumes to transport modes and determines transportation frequencies over a Planning horizon. This generic model is applied to a real-life case in Flanders, the northern region of Belgium. Computational results show that multimodal truck and inland water transportation can compete with truck transport by avoiding or reducing transhipments and using barge convoys.
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intermediate facilities in freight transportation Planning a survey
Transportation Science, 2016Co-Authors: Gianfranco Guastaroba, Maria Grazia Speranza, Daniele VigoAbstract:Consolidation of freight and merging operations are essential for transportation companies to reduce costs and improve the level of service provided to customers. Such operations take place in intermediate facilities or terminals located between the origins and the destinations of freight. This survey reviews the main contributions from the operations research literature on freight transportation Planning problems where the presence of intermediate facilities has a strong impact on the cost of the system and on how goods are delivered. In particular, we focus on the Tactical Planning issues arising in this context. We have identified three classes of problems with intermediate facilities: vehicle routing problems, transshipment problems, and service network design problems. For each class of problems we provide an overview of the main problem variants, survey the methods used for their solution, and indicate open research directions.
Ali Eshragh - One of the best experts on this subject based on the ideXlab platform.
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Tactical supply chain Planning under a carbon tax policy scheme: A case study
International Journal of Production Economics, 2015Co-Authors: Behnam Fahimnia, Alok Choudhary, Joseph Sarkis, Ali EshraghAbstract:Greenhouse gas emissions are receiving greater scrutiny in many countries due to international forces to reduce anthropogenic global climate change. Industry and their supply chains represent a major source of these emissions. This paper presents a Tactical supply chain Planning model that integrates economic and carbon emission objectives under a carbon tax policy scheme. A modified Cross-Entropy solution method is adopted to solve the proposed nonlinear supply chain Planning model. Numerical experiments are completed utilizing data from an actual organization in Australia where a carbon tax is in operation. The analyses of the numerical results provide important organizational and policy insights on (1) the financial and emissions reduction impacts of a carbon tax at the Tactical Planning level, (2) the use of cost/emission tradeoff analysis for making informed decisions on investments, (3) the way to price carbon for maximum environmental returns per dollar increase in supply chain cost.
Ana Paula Barbosapovoa - One of the best experts on this subject based on the ideXlab platform.
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stochastic programming approach for the optimal Tactical Planning of the downstream oil supply chain
Computers & Chemical Engineering, 2018Co-Authors: Camilo Lima, Susana Relvas, Ana Paula BarbosapovoaAbstract:Abstract This paper develops a multistage stochastic programming to optimally solve the distribution problem of refined products. The stochastic model relies on a time series analysis, as well as on a scenario tree analysis, in order to effectively deal and represent uncertainty in oil price and demand. The ARIMA methodology is explored to study the time series of the random parameters aiming to provide their future outcomes, which are then used in the scenario-based approach. As the designed methodology leads to a large scale optimization problem, a scenario reduction approach is employed to compress the problem size and improve its computational performance. A real-world example motivates the case study, based on the downstream oil supply chain of mainland Portugal, which is used to validate the applicability of the stochastic model. The results explicitly indicate the performance of the designed approach in tackling large and complex problems, where uncertainty is present.
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an application of a multi agent auction based protocol to the Tactical Planning of oil product transport in the brazilian multimodal network
Computers & Chemical Engineering, 2013Co-Authors: Roni F Banaszewski, Ana Paula Barbosapovoa, Lucia Valeria Ramos De Arruda, Jean Marcelo Simao, Cesar Augusto Tacla, Susana RelvasAbstract:Abstract The transportation Planning of oil products in Brazil's multimodal network is a complex problem that involves various negotiations between decentralized entities in order to agree on which products to transfer, their amounts, and the allocation of shared resources. Due to such complexity, there is a clear need for a decision support tool. This paper presents a model for solving this problem based on a new multi-agent auction protocol. The developed model is used to solve a real scenario of the Brazilian oil supply chain in a multi-level topological approach.
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simultaneous design and Planning of supply chains with reverse flows a generic modelling framework
European Journal of Operational Research, 2010Co-Authors: Maria Isabel Gomes Salema, Ana Paula Barbosapovoa, Augusto Q NovaisAbstract:The increase in societal awareness towards environmental issues has accrued the responsibility of goods producers, which at present came to encompass the entire product life cycle. Recently, the efficient design and operation of supply chains with return flows have, in particular, become a major challenge for many companies, given the high number of factors involved and their intricate interactions. In this paper, a multi-period and multi-product network model for the simultaneous design and Planning of supply chains with reverse flows is proposed. A graph approach based on the conventional concepts of nodes and arcs is employed to model the network, where it is assumed that any network node is a transformation point of inbound into outbound flows, which in the limit may not differ, and that related arcs describe products flows along the chain. In here the formulation of time adopts a management perspective, i.e., the strategic design of the supply chain is dealt simultaneously with the Tactical Planning of its operation, which covers supply, production, storage and distribution. An example based on a Portuguese industry case is studied in order to validate both the applicability and adequacy of the model to real world problems.
Behnam Fahimnia - One of the best experts on this subject based on the ideXlab platform.
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Tactical supply chain Planning under a carbon tax policy scheme: A case study
International Journal of Production Economics, 2015Co-Authors: Behnam Fahimnia, Alok Choudhary, Joseph Sarkis, Ali EshraghAbstract:Greenhouse gas emissions are receiving greater scrutiny in many countries due to international forces to reduce anthropogenic global climate change. Industry and their supply chains represent a major source of these emissions. This paper presents a Tactical supply chain Planning model that integrates economic and carbon emission objectives under a carbon tax policy scheme. A modified Cross-Entropy solution method is adopted to solve the proposed nonlinear supply chain Planning model. Numerical experiments are completed utilizing data from an actual organization in Australia where a carbon tax is in operation. The analyses of the numerical results provide important organizational and policy insights on (1) the financial and emissions reduction impacts of a carbon tax at the Tactical Planning level, (2) the use of cost/emission tradeoff analysis for making informed decisions on investments, (3) the way to price carbon for maximum environmental returns per dollar increase in supply chain cost.