Teodor Gabriel CrainicSchool of Management, Université du Québec à Montréal · Management and Technology
Teodor Gabriel Crainic
PhD
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Publications (391)
It is with the sadness of the loss of a dear friend interwoven with the pleasure of sharing the tribute to his memory that we announce the publication by Springer of the book Combinatorial Optimization and Applications - A Tribute to Bernard Gendron https://link.springer.com/book/10.1007/978-3-031-57603-4
Starting from the exceptional contribution...
This book aims to honour the memory and scientific legacy of Professor Bernard Gendron, who left this world in July 2022, by providing a state-of-the-art reference for researchers and graduate students in Operations Research, Combinatorial Optimization, and related fields, through a combination of surveys, expository articles, and focused methodolo...
Capacity planning may be defined as the process of determining the appropriate mix and quantity of resources to meet demand. We focus on Consolidation-based Freight Transportation and Logistics in this chapter, particularly on the planning of the supply capacity required to satisfy known or predicted, customer or internally-generated demand. It is...
Multilayered networks are used to model systems with multiple interacting components, each being represented by a network layer. More than two layers may be involved. The Operations Research multi-layer network term is generally associated with complex multilayered problem settings, frequently encountered in planning transportation and telecommunic...
Future city logistics systems focus on multi-tier and multimodal transportation, an integration of freight movements into mobility and minimal spatial requirements.
The presented planning approach is based on two-tier service network design, where transportation services with routes, departure time windows and capacities are given, and waiting time...
Scheduled Service Network Design supports consolidation-based freight carriers in setting up a transportation network by selecting the transportation services to operate, with their schedules, and the itineraries of the commodities to move. We propose a new formulation to the problem that represents time in its continuous nature, directly over the...
Purpose
This study aims to deepen the understanding of the challenges and implications entailed by deploying mobile clinics in conflict zones to reach populations affected by violence and cut off from health-care services.
Design/methodology/approach
This research combines an integrated literature review and an instrumental case study. The literat...
We address the Multicommodity Capacitated Fixed-charge Network Design problem with uncertain demands, which we formulate as a two-stage stochastic program. We rely on the progressive hedging (PH) algorithm of Rockafellar and Wets where the subproblems are defined using scenario groups. To address the problem, we propose an efficient matheuristic ap...
The synchronized multi-commodity multi-service Transshipment-Hub Location Problem is a hub location problem variant faced by a logistics service provider operating in the context of synchromodal logistics.
The provider must decide where and when to locate transshipment facilities in order to manage many customers' origin-destination shipments with...
This study focuses on investigating the tactical planning of an integrated multi-stakeholder system in which revenue management concepts including shipper categories, demand classification, penalty costs for demand satisfaction outside of prescribed time-windows, and offering services with bundles are addressed. The aim of the tactical planning in...
Multilayer network design represents an important problem class when interwoven design decisions must be simultaneously considered. Examples of such cases are the selection of trains and blocks in freight rail transportation and the selection of physical and logical paths in telecommunications. Each set of those design variables are then defined on...
When demand for transportation is low or sparse, traditional transit cannot provide efficient and good-quality service, because of its fixed structure. For this reason, mass transit is evolving toward some degree of flexibility. Although the extension of Dial-a-Ride systems to general public meets such need of adaptability, it presents several draw...
The objective of the paper is to study the integration of revenue management considerations into service network design models targeting the tactical planning of intermodal consolidation-based freight transportation carriers. Revenue management strategies and mechanisms are broadly used within passenger transportation. Although identified as a desi...
We propose a solution approach for stochastic network design problems with uncertain demands. We investigate how to efficiently use reduced cost information as a means of guiding variable fixing to define a restriction that reduces the complexity of solving the stochastic model without sacrificing the quality of the solution obtained. We then propo...
This paper studies the multi-commodity two-echelon capacitated vehicle routing problem with time windows. Specifically, we take customer-specific origin to destination, non-substitutable demands into account. The main components are: (i) first echelon tours, (ii) second echelon tours and (iii) movement of commodities from first echelon to second ec...
The bin packing problem is one of the most studied combinatorial optimization problem. This paper proposes two novel bin packing problem settings with many practical applications, in particular in logistics capacity planning. Both problems explicitly consider, besides the classical bin-selection costs, the item and bin-specific item-to-bin assignme...
We address the tactical-planning problem for an extended two-tiered City Logistics system. This more realistic problem setting, compared to the literature, integrates inbound and outbound demands, different transportation modes combining traditional, road-based, carriers with modes and vehicles of mass transport, such as light and regular rail. Asi...
Classical Lagrangian relaxations for the multicommodity capacitated fixed-charge network design problem are the so-called flow and knapsack relaxations, where the resulting Lagrangian subproblems decompose by commodities and by arcs, respectively. We introduce node-based Lagrangian relaxations, where the resulting Lagrangian subproblem decomposes b...
To improve efficiency and sustainability in synchromodal logistics, it becomes crucial to mitigate the disruptive effects caused by non-synchronized operations. In this work, we study the Synchronized Location-Transshipment Problem in which the decisions on the facilities to select are fundamental to ensure the synchronization of flows and the corr...
This work focuses on a particular node of the intermodal chain of transportation, i.e. the maritime port area that represents the link between rail and sea transportation modes. Since this exchange node of the chain has not been addressed much yet, the aim of the present study is to provide a description of the process of rail operations in port ar...
Railroads provide economically priced, environmental-friendly, and timely freight transport services, implementing a double consolidation policy, which groups cars into blocks and blocks into trains. Tactical operation plans are built to select the train services and schedules to operate, the blocks to build at each terminal, the routes of blocks a...
Service Network Design designates issues, decisions, and network-design models aimed to plan the activities and resources of the supply side of a transportation system, aiming to satisfy demand efficiently, profitably, and within the quality standards agreed upon with the customers generating this demand. Service Network Design is particularly rele...
Network design problems arise whenever optimal choices have to be made that can be represented conceptually as the selection of a subset of links in a graph. Typically, these optimal choices are the result of complex tradeoffs between various types of costs and constraints. In particular, most network design problems involve fixed costs associated...
This chapter is dedicated to exact algorithms for single-commodity and multicommodity fixed-charge network design. These problems are notoriously difficult, since they are in general strongly NP-hard. In addition, their objective function includes both fixed design costs and variable transportation costs, which results in complex tradeoffs that com...
City Logistics aims to reduce the nuisances, e.g., congestion and the environmental footprint, associated to the transportation of freight within urban areas, while sustaining the social and economic development of the organizations and cities involved. City Logistics achieves its goals through integrated planning of operations. Yet, it also displa...
Benders decomposition is a broadly used exact solution method for stochastic programs, which has been increasingly applied to solve transportation and logistics planning problems under uncertainty. However, this strategy comes with important drawbacks, such as a weak master problem following the relaxation step that confines the dual cuts to the sc...
This chapter introduces problems and models that involve design decisions captured with arc-based binary variables that typically model fixed costs. We distinguish whether the demand can be represented as a single commodity or as multiple commodities, whether or not there are capacities, and whether or not there are variable transportation costs in...
Heuristics and metaheuristics are widely used to tackle difficult network design problems. We first present fundamental concepts for the development of heuristic approaches, such as search spaces, neighborhoods, and populations of solutions. The main heuristic and metaheuristic solution methods are then introduced: constructive and Local Search heu...
Rail transportation provides economically-priced, environmentally-friendly, and timely freight transportation services at the regional, national, and international levels. To achieve this performance, railroads operate mostly according to a double consolidation policy, as cars are grouped into blocks, which are grouped into trains, and set up tacti...
This paper proposes a solution approach for the multicommodity capacitated fixed-charge network design problem with uncertain demand modeled as a two-stage stochastic program. The proposed learning-based matheuristic combines heuristic search techniques with mathematical programming. It provides a systematic approach to identifying structures of go...
Station-based bike-sharing systems rely on bike redistribution to provide users with an adequate service level. We propose a novel formulation of service network design that coordinates redistribution decisions in space and time to plan regular master tours. This formulation explicitly integrates resource-management decisions by considering a limit...
We address the stochastic scheduled service network design problem with quality targets and uncertainty on travel times. This important problem, raising in the tactical planning process of consolidation-based freight carriers, has been little studied up to now. We define the problem considering quality targets for on-time operation of services and...
Many methods that have been proposed to solve large-scale MILP problems rely on the use of decomposition strategies. These methods exploit either the primal or dual structures of the problems by applying the Benders decomposition or Lagrangian dual decomposition strategy, respectively. In “The Benders Dual Decomposition Method,” Rahmaniani, Ahmed,...
Blocking constitutes an important rail freight transport operation, by which cars with potentially different origins and destinations are grouped to be moved and handled as a single unit, yielding economies of scale. We address the tactical block-planning problem for intermodal railroads, which has been little studied so far. We propose a new block...
We examine an innovative system for organizing deliveries in a collaborative fashion for an n-tier hyperconnected city logistics system. We focus on the tactical planning of services within the first tier of the system, i.e., from external zones generally located on the outskirts of the city (logistics platforms, urban/city distribution/consolidati...
The shipment of hazardous materials is important and many of these products are flammable, explosive or radioactive. Despite high security standards, accidents still happen and the transportation of hazmat causes fear among the population. Therefore, the society expects authorities to distribute the risk fairly. To support such a fair distribution,...
We propose a scheduled service network design model that simultaneously addresses strategic decisions regarding fleet sizing and allocation, including acquisition and outsourcing, as well as tactical decisions regarding a repeatable transportation plan and schedule. Moreover, as a well-sized fleet and a well-designed transportation plan should be a...
Motivated by an actual problem of a national postal service company, we introduce and define a new two-echelon location-routing problem (2E-LRP). The 2E-LRP is defined in a two-echelon distribution system where products are transported from origins to destinations through intermediate facilities. A major question that arises in a two-echelon distri...
We present a multi-ob’jective two-echelon vehicle routing problem with vehicle synchronization and ‘grey zone’ customers arising in the context of urban freight deliveries. Inner-city center deliveries are performed by small vehicles due to access restrictions, while deliveries outside this area are carried out by conventional vehicles for economic...
It is well known that the bin packing problem is one of the most studied
combinatorial optimization problems. This paper proposes two novel variants of this problem
that have practical applications in logistics planning. These two new models are aimed at
minimizing, not only the cost of selecting the bins, but also the costs of assigning the items...
We study the Multi-trip Separate Pickup and Delivery Problem with Time Windows at Customers and Facilities (MT-PDTWCF), arising in two-tiered city logistics systems. The first tier refers to the transportation between the city distribution centers, in the outskirts of the city, and intermediate facilities, while the second tier refers to the transp...
We study the value of deterministic solutions, in particular their quality and upgradability, in addressing stochastic network design problems, by analyzing their time-dependent formulations known as scheduled service network design problems in freight transportation planning. We study several problem variants and models and investigate, for each c...
This paper studies the two-echelon capacitated vehicle routing problem with time windows. The first echelon consists of transferring freight from depots to intermediate facilities (i.e., satellites), whereas the second echelon consists of transferring freight from these facilities to the final customers, within their time windows. We propose two pa...
The scope of this paper is to advance the investigation into the importance of introducing uncertainty in service network design (SND) formulations by examining the uncertainty of travel times, a phenomenon that has been little studied up to now. The topic of our research thus is the stochastic scheduled service network design problem with service-...
The chapter presents a general picture of parallel meta-heuristic search for optimization. It recalls the main concepts and strategies in designing parallel meta-heuristics, pointing to a number of contributions that instantiated them for neighborhood- and population-based meta-heuristics, and identifies trends and promising research directions. Th...
The explicit consideration of uncertainty is essential in addressing most planning and
operation issues encountered in the management of complex systems. Unfortunately,
the resulting stochastic programming formulations, integer ones in particular, are
generally hard to solve when applied to realistically-sized instances. A common
approach is to con...
City logistics solutions have been implemented in many cities in a number of countries around the world. This chapter presents the simulation of an urban logistics solution in a North American city. It also presents the different types of models used in urban areas for goods movement simulations. The chapter evaluates the efficiency of using an urb...
This paper describes a Benders decomposition algorithm capable of efficiently solving large-scale instances of the well-known multicommodity capacitated network design problem with demand uncertainty. The problem is important because it models many applications, including telecommunications, transportation, and logistics. This problem has been tack...
Intermodal transportation refers to multimodal chains or networks involving at least two transportation modes, freight being packed into a "container" and not being handled at intermodal-transfer terminals on its trip from its origin to its destination. This characterization makes intermodal transportation a multi-actor complex system involving a b...
This paper presents a general methodology that addresses the load planning problem for intermodal trains. We propose a model that can deal with single- or double-stack railcars as well as arbitrary containers-to-cars matching rules. Moreover, we model weight and center of gravity constraints, stacking rules and technical loading restrictions associ...
Contracting with carriers or third-party logistics firms is a way to secure transportation or warehousing capacity for the next planning period. However, contracts are concluded under uncertainty regarding the demand of loads to be transported, the availability of contracted capacity and of the extra one if needed. The question is how much to contr...
Research on the location-routing problem (LRP) is very active, producing a good number of effective exact and approximated solution approaches. It is noteworthy that most of the contributions present in the literature address the single-commodity LRP, whereas the multi-commodity case has been scarcely investigated. Yet, this issue assumes an import...
The Benders decomposition algorithm has been successfully applied to a wide range of difficult optimization problems. This paper presents a state-of-the-art survey of this algorithm, with an emphasis on its use in combinatorial optimization. We discuss the classical algorithm, the impact of the problem formulation on its convergence, and the relati...
In this paper, we consider two-tiered city logistics systems accounting for both the inbound and outbound traffic, that have not been taken into account in models and algorithms for vehicle routing research. The problem under study, called the Multi-trip Pickup and Delivery Problem with Time Windows and Synchronization, has two sets of intertwined...
We present a new planning model for freight consolidation carriers, one that links strategic, resource-acquisition and allocation decisions with tactical, service network design-related decisions. Specifically, like service network design models that recognize resource constraints, the model selects services and routes both commodities and the reso...