Publications by Michel Bierlaire

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The aim of this paper is to analyze and to improve the current planning process of the passenger railway service in light of the recent railway market changes. In order to do so, we introduce the Passenger Centric Train Timetabling Problem. The originality of our approach is that we account for the passenger satisfaction in the design of the timetable. We consider both types of timetable(s): cyclic and non-cyclic. The problem is modeled as a Mixed Integer Linear Programming (MILP) problem with an objective

In this study, we integrate a schedule design and fleet assignment model and a demand model into an optimization problem to maximize the revenue of an airline. The model considers spill and recapture effects to cope with capacity restrictions. For the demand modeling, fares, fare classes, departure times and number of stops are modeled by linear and nonlinear specifications. A heuristic method is proposed to deal with the high complexity of the resulting mixed integer nonlinear problem.

We propose a novel approach to pedestrian flow characterization. The definitions of density, flow and velocity existing in the literature are extended through a data-driven spatio-temporal discretization framework. The framework is based on three-dimensional Voronoi diagrams. The new definitions are (i) independent from an arbitrarily chosen discretization; (ii) appropriate for the multi-directional composition of pedestrian traffic; (iii) able to reflect the heterogeneity of the pedestrian population; and

Although different vehicle sharing systems (VSSs) use different vehicle types, the management challenges and optimization problems to be solved are similar or even the same. This observation led us to create a generalized and holistic VSS management framew ...

Automatic facial expression recognition finds applications in various fields where human-machine interactions are involved. We propose a framework based on discrete choice models, where we try to forecast how a human person would evaluate the facial expression, choosing the most appropriate label among a given list. After having applied the framework successfully on static images, we investigate the possibility to apply it on video sequences.

We consider the problem of assigning gates to a large airline at its hub airport in both planning and operations mode. The first objective in planning mode assigns airport gates for a given passenger flow data and pedestrian distances between the gates, such that maximum connection revenue is realized. The second objective aims to schedule flights to gates in as few manpower zones as possible to minimize operating costs. The third objective ensures that the time between a departure and next arrival at the s

The integration of choice models in mixed integer linear programming (MILP) is appealing to operators because it provides a better understanding of the preferences of customers while planning for their systems. However, the complexity of choice models leads to mathematical formulations that are highly nonlinear and non convex in the variables of interest, and therefore difficult to be included in MILP. In this research, we present a general framework that overcomes these limitations by relying on simulation

This review discusses some issues related to the use of simulation in transportation analysis. Potential pitfalls are identified and discussed. An overview of some methods relevant to the use of an advanced simulation tool in an optimization context is also provided.

On 5 September 2015, the German government suspended the EU’s Dublin III regulations, allowing all asylum seekers to apply for asylum in Germany. This policy change motivated more than one million people, especially Syrians, Afghans, and Iraqis, to enter the country. This study examines the impact of this policy change on migration aspirations and actions in 11 Arab countries, assessing whether it increased migration pressure toward Germany. We find that while the policy raised migration aspirations, it did

Mutual information is a widely used similarity measure for aligning multimodal medical images. At its core it relies on the computation of a discrete joint histogram, which itself requires image samples for its estimation. In this paper we study the influe ...

Airline schedules are rarely performed as planned because of irregularities such as delays, unpredicted maintenances or bad weather conditions. Recover from a disrupted schedule as quickly as possible is a hard and high priority problem for practitioners: given a disrupted situation they have to take decisions in order to minimize the number of canceled flights and the average delay respecting all technical requirements. We present a column generation based algorithm to solve the airplane recovery problem i

A macroscopic loading model for multi-directional, time-varying and congested pedestrian flows is proposed in this paper. Walkable space is represented by a network of streams that are each associated with an area in which they interact. To describe this interaction, a stream-based pedestrian fundamental diagram is used that relates density and walking speed in multi-directional flow. The proposed model is applied to two different case studies. The explicit modeling of anisotropy in walking speed is shown t

Over the last years, international sea-freight container transportation has grown dramatically and container terminals play nowadays a key-role in the global shipping network. The increased competitiveness among terminals requires more and more efficiency in container operations, in order to minimize ships turnaround time. In this work, we focus on the optimization of yard operations, which are critical for the terminal efficiency, because of their impact on all the other operations (most operations origina

Interconnected logistics system can play an important role towards having a more sustainable green freight transport. Recently, after introducing the concept of Physical Internet (PI), researchers have started to explore the opportunities and challenges th ...

In this paper, we formulate a mixed integer linear program (MILP) for the simulated maximum likelihood estimation (MLSE) problem and devise a Benders decomposition approach to speed up the solution process. This framework can be applied to any advanced dis ...

Pedestrian modeling is emerging as a tool for designing new infrastructures and optimizing the use of current ones. Given sensor traces, we are interested in developing a dynamic model that can predict the destination chain of an individual in pedestrian facilities. As a first step, we developed a methodology to collect activity-episodes sequences from scarce data, directly modeling the imprecision in the measure. It generates several candidate lists of activity-episodes sequences associated with a correspo

Microsimulation of urban systems evolution requires synthetic population as a key input. Currently, the focus is on treating synthesis as a fitting problem and thus various techniques have been developed, including Iterative Proportional Fitting (IPF) and ...

We propose a new type of timetable that would combine both the regularity of the cyclic timetables and the flexibility of the non-cyclic ones. In order to do so, several combinations of the two timetables are considered. The regularity is incorporated in their design and the flexibility is evaluated using the passenger satisfaction (in monetary units). Each of the tested timetables is constructed using the Passenger Centric Train Timetabling Problem, that is solved using a simulated annealing heuristic. The

In this paper, we propose a methodology to use the communication network infrastructure, in particular WiFi traces, to detect the sequence of activity episodes visited by pedestrians. Due to the poor quality of WiFi localization, a probabilistic method is ...

We apply the Metropolis-Hastings algorithm to efficiently sample from arbitrary paths distributions in a general network. Paths can be generalized into all-day travel plans through, e.g., an appropriate network expansion. The Metropolis-Hastings algorithm creates a Markov chain of paths, which resembles DTA simulations that can also be phrased as Markov chains. A combination of both chains could lead to better understood DTA simulations that avoid the arbitrariness of current choice set generation procedure

Michel Bierlaire

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Passenger Centric Train Timetabling Problem

Integrated airline schedule planning with supply-demand interactions

Data-driven characterization of pedestrian flows

Vehicle sharing systems: A review and a holistic management framework

Automatic facial expression recognition: a discrete choice approach

Generalized Airport Gate Assignment

Integrating advanced discrete choice models in mixed integer linear optimization

Simulation and optimization in transportation: a short review

From Aspiration to Action? The Impact of Germany's 2015 Dublin III Suspension on Migration Intentions in Arab Countries

Halton Sampling for Image Registration Based on Mutual Information

Airline Disruptions: Aircraft Recovery with Maintenance Constraints

A dynamic network loading model for anisotropic and congested pedestrian flows

Yard Optimization at Sea Container Terminals

The Impact of Collaborative Scheduling and Routing for Interconnected Logistics: A European Case Study

A Benders decomposition for maximum simulated likelihood estimation of advanced discrete choice models

A Pedestrian Destination-Chain Choice Model from Bayesian Estimation of Pedestrian Activities using Sensors Data

Simulation based population synthesis

Hybrid Cyclicity: Combining The Benefits Of Cyclic And Non-Cyclic Timetables

A Bayesian Approach to Detect Pedestrian Destination-Sequences from WiFi Signatures

Choice set generation for iterated DTA simulations