This special issue of the Journal of Scheduling contains ten papers presented at the Twelfth Workshop on Models and Algorithms for Planning and Scheduling Problems (MAPSP 2015), held from June 8 to June 12, 2015, in La Roche-en-Ardenne, Belgium.

This text/reference examines classic algorithms, geometric diagrams, and mechanical principles for enhanced visualization of statistical estimation procedurs and mathematical concepts in physics, engineering, and computer programming - stressing the role of geometric and mechanical representations in the design and generation of numericl models for applications in physical science. Visualizing Statistical Models and Concepts provides methods to determine the position of a multivariate location parameter ... offers techniques to fit a plane or curved surface to multivariate data ... considers geomechanical dynamics for linear and non linear programming ... discusses mathematical approaches to estimate and predict potential energy, force, and strain of system components...and analyzes data sets generated by transitive and nontransitive pairwise preference orderings.

La complexité, l'imprévisibilité croissantes de l'environnement et de la structure interne des entreprises contraignent le gestionnaire à tendre vers une description probabiliste de l'univers. Le passage de la théorie classique, paramétrique, incluant la variabilité des données dans un contexte déterministe et discret, à la théorie stochastique continue, se fait progressivement. Chaque étape est illustrée au moyen d'exemples concrets. Un logiciel (sur CD-ROM) permet la résolution immédiate des problèmes propres à l'utilisateur.

Cette recherche se concentre sur la création d'un environnement de réalité virtuelle visant à améliorer les compétences en prise de parole en public. L'objectif initial est la conception d'une audience virtuelle réaliste à l'aide de techniques de réalité virtuelle et de photoréalisme. Ensuite, l'attention s'est portée sur l'analyse de la voix et du discours, en particulier la détection des émotions dans la voix des orateurs. Une base de données émotionnelle de haute qualité a été en cours de développement, ainsi que des recherches sur des algorithmes d'apprentissage automatique et profond pour cette analyse. Enfin, des avatars animés par l'intelligence artificielle sont en cours de création pour offrir une expérience d'apprentissage immersive aux orateurs. Cette recherche vise à améliorer la formation à la prise de parole en public en explorant les synergies entre la réalité virtuelle, l'analyse émotionnelle vocale et l'intelligence artificielle.

I have been invited by Prof. Dr. Catherine Cleophas as an external guest to the "Revenue Management Colloquium" in Aix-la-Chapelle from March 25 to March 26. The aim is to present my own doctoral project and discuss the presentations of other PhD students

The airline industry changed dramatically in 1978 when it became deregulated. Operations research analysts played a critical role after deregulation by developing algorithms and decision-support systems designed to help airlines to maximize their revenue. More than thirty-five years after deregulation, the airline industry is faced with new challenges. The increased use of the Internet as the major distribution channel and the increased market penetration of low cost carriers have led to an increasing interest in using discrete choice models to model air travel demand as the collection of individual's decisions.

This research focuses on enhancing public speaking training through the integration of an emotional speech dataset and Virtual Reality (VR) technology. The study recognizes the significance of emotions in effective communication and highlights the potential of AI techniques for emotion detection. To address the limitations of existing datasets, a high-quality emotional speech dataset is developed in French and English, incorporating professional actor recordings and Text-to-Speech software-generated samples. The dataset is then validated through subjective evaluation experiments. By leveraging VR technology, the research aims to create an immersive and interactive training environment where participants can practice speaking in front of virtual avatars that react authentically based on their emotional states. This research contributes to the advancement of public speaking training and establishes a valuable resource for emotional speech analysis in various applications, including VR, robots, and virtual assistants.

Demand forecasting, price optimization and capacity controls form three major tools of revenue management. Over the past few decades, each discipline has generated a great deal of research but has typically been studied separately from the others. Yet, better understanding their relationship gives an airline the opportunity to increase its profitability. In prior work, Tim Jacobs and colleagues introduced a macro-level metric known as the ‘Price Balance Statistic (PBS)’ for evaluating the quality of a given pricing strategy and guiding a search algorithm to identify an optimal alignment between pricing structure, scheduled capacity and RM controls using marginal revenue principles. The aim of our work is to incorporate additional modeling improvements to the PBS. The current model formulation uses price elasticity as input parameters and assumes perfect independency between the different fare classes. However, in reality, a passenger demand fluctuates between classes based on differences in prices. We propose to use instrumented variable linear regression methods to obtain parameter estimates for price elasticities and cross-elasticities. This modification incorporates accurate price elasticities but also the impact of a change in one fare class on another through the cross-elasticities.

This study formulates an itinerary choice model that is consistent with those used by industry and corrects for price endogeneity using a control function that uses several types of instrumental variables. We estimate our models using database of more than 3 million tickets provided by the Airlines Reporting Corporation. Results based on Continental U.S. markets for May 2013 departures show that models that fail to account for price endogeneity overestimate customers’ value of time and result in biased price estimates and incorrect pricing recommendations. Extensions to advanced discrete choice models show the importance of accounting for inter-alternative substitution for products that share similar departure times.

Airline itinerary choice models support many multi-million dollar decisions, i.e., they are used to evaluate potential route schedules. Classic models suffer from major limitations, most notably they use average fare information but to not correct for price endogeneity. We use a novel database of airline tickets to estimate itinerary choice models using detailed fare data and compare these to classic itinerary choice models that use aggregate fare information but correct for price endogeneity.

The aim of this work is to propose a Relax-And-Fix heuristic to build a good initial solution to the 3D BPP. First, a mathematical formulation has been developed taking into account several types of constraints such as the stability and fragility of the boxes to pack, their possibility to rotate, the weight distribution inside the bins and their special shapes. Since this model contains a lot of integer variables, we have decided to apply the Relax-and-Fix method. We have selected several sets of variables to be the branching variables and carried out some tests.

This project has been initiated by a main European freight airport. The goal is to optimize the aircraft refueling process which relies on a given set of trucks. The underlying process can be defined as a vehicle routing problem with capacity and time windows. We resort to a branch and price approach for which we first analyze the impact of different parameters on the performance of the algorithm. Due to the stochastic nature of the demand and time windows in this context, we are also working on a priori (split delivery) and a posteriori (efficient re-optimization) measures.

This research aims to develop a new mixed integer linear program to solve the containers assignment problem when pickup and deliveries are considered. Given a pool of ULDs and an aircraft with multiple destinations, we want to obtain a loading plan determining at which positions the ULDs must be assigned in order to minimize simultaneous the quantity of fuel consumed and the number of re-handles. The loading plan should also ensure a number of structural, safety and manoeuvrability constraints. The model has been tested on real instances and provides encouraging results.

Présentation du projet Teaching with VR, qui associe des enseignants-chercheurs de 4 facultés pour développer des environnements en réalité virtuelle au service de l'enseignement en sciences humaines. Trois environnements sont montrés, qui peuvent être déclinés pour différentes disciplines (psychologie, architecture, marketing, etc.), en fonction de dispositifs ajoutés aux environnements.

Despite its importance, the specific issue of performance and reading of sketches in augmented reality does not seem to have been analyzed recently. Indeed, even if many articles have been published in connection with VR or RA in architecture, the questions studied are very varied and often related to specific applications. Recent literature, based on new technologies available since 2016, is also very limited. The research presented here was carried out within the pedagogical framework offered by the construction course taught to first-year students in the Faculty of Architecture of ULiège. The general objective of this course is to introduce students to a graphic approach framework that links construction technologies to the development of an architectural project. Students explore different construction techniques through the drawing of technical details. A first exploratory approach was carried out last year during the development of a prototype. It shows us the feasibility of the project and some pitfalls to avoid. The main objective of the project is to study the impact of augmented reality on the performance and skills acquisition of architecture students. It focuses on reading plans and sketches of technical construction drawings in order to identify the contributions of 3D spatialization.

Nous présentons un projet visant à créer une base de données émotionnelle (audio & vidéo, en français & en anglais) de haute qualité, équilibrée phonétiquement, contenant les six émotions de base d'Ekman et d'autres émotions communes lors de la prise de parole en public. Le but de cette base de données sera de détecter automatiquement les émotions chez un individu grâce à l'intelligence artificielle. Pour chaque langue, nous avons conçu deux études. La première consiste à enregistrer des phrases phonétiquement équilibrées avec les 10 émotions (et 2 niveaux d'intensité différents) produites par 12 acteurs. La deuxième implique la validation de chaque enregistrement par 25 juges différents. Nous pensons que notre projet sera notamment utile pour la formation à la prise de parole en public et pour la création d'environnements de formation en réalité virtuelle. En outre, notre base de données sera publique et ouverte à la communauté scientifique et pourra être utilisée à des fins de formation.

Demand forecasting, price optimization and capacity controls form three major tools of revenue management. Over the past few decades, each discipline has generated a great deal of research but has typically been studied separately from the others. Yet, better understanding their relationship gives an airline the opportunity to increase its profitability. In prior work, Tim Jacobs and colleagues introduced a macro-level metric known as the ‘Price Balance Statistic (PBS)’ for evaluating the quality of a given pricing strategy and guiding a search algorithm to identify an optimal alignment between pricing structure, scheduled capacity and RM controls using marginal revenue principles. The aim of our work is to incorporate additional modeling improvements to the PBS. The current model formulation uses price elasticity as input parameters and assumes perfect independency between the different fare classes. However, in reality, a passenger demand fluctuates between classes based on differences in prices. We propose to use instrumented variable linear regression methods to obtain parameter estimates for price elasticities and cross-elasticities. This modification incorporates accurate price elasticities but also the impact of a change in one fare class on another through the cross-elasticities.

We address the problem of allocating containers into predefined positions of a carrier, in this case aircraft, under several realistic structural and safety constraints. The originality of our approach is to allow multi-trips with pickup and delivery at some intermediate locations. The objective is to minimize the economic and environmental costs including the impact of the intermediate operations. We resort to an integer linear model. Numerical experiments have been performed using a standard B\&C library. Heuristics are developed to speed up the process.

We address the problem of allocating containers into predefined positions of a carrier, in this case aircraft, under several realistic structural and safety constraints, including the management of several doors. The originality of our approach is to allow multi-trips with pickup and delivery at some intermediate locations. The objective is to minimize the economic and environmental costs including the impact of the intermediate operations. We resort to an integer linear model. Numerical experiments have been performed using a standard B&C library. The cost impact is measured. The Airline Group of the International Federation of Operational Research Societies, composed of professionals and academics, has awarded us the price of the "Best technical presentation" for this work.

Speaking out in public is one of the most important skills a person should develop. It is especially true regarding business, law, and education. To efficiently teach students practical skills in their learning journey, we need to prepare and train them. In this paper, we focus on mooting, also known as a mock trial, which is often used in universities to achieve this goal. Like every training module, it can be logistically challenging to implement. In the past years, Virtual Reality (VR) has shown to be particularly useful when it comes to learning by doing. In VR, participants are immersed in a controlled virtual environment. This paper aims to validate the implementation of a comprehensive, automated, artificial intelligence-based VR application for mooting to improve participant performance. Semi-structured interviews will be conducted at UK, and Belgian universities and an experiment with 125 participants will be conducted within the same institutions to determine the characteristics of such an environment. We will also know if there are significant differences between Belgium and the United Kingdom that must be considered when designing it. Of course, the results will not be limited to mooting and can be easily adapted to other areas where speaking in public is a competency important to learn. For example, in business processes: the sales representative who presents a product to customers, the tourist guide visiting a city with a group, and the manager who defends his project in front of stakeholders... In future work, we will use our environment during the training of the students to confront them in various situations in response to their speech.

Introduction/Context: Nowadays public speaking is a vital skill in many circumstances and in very different fields: the sales representative who presents a product to customers, the manager who defends his project in front of stakeholders, the candidate during a job interview, the professor in front of students, etc. However, social anxiety may impede oral presentation performances . Repeated training in front of an audience can help to better control the speaker’s emotions and skills, and improve speaking performances (Wallach et al., 2009). Given that training in front of a real audience can be logistically difficult to organize, virtual reality (VR) can be the solution. Nevertheless, the emotional impact of the virtual audience on the speaker will depend on the emotional valence and arousal they attribute to the audience’s avatars. Aim: The goal of the present study is to assess the emotional valence and arousal attributed to the avatars of a new virtual audience, depending on the avatars’ attitude. Method and material: Based on the methods from Chollet & Scherer (2017), 125 adults participated in this study. They rated the emotional valence and arousal of 8 avatars depending on their body posture, their face’s expressions, or their head movements. Results and conclusions: Results show that head movements were more readily linked to the emotional valence attributed to the avatars by the participants than were body postures and facial expressions. Furthermore, arousal seems to be directly linked with head movements and facial expressions. Full results from each parameter will be discussed.

Anatomy and histology are cornerstones of preclinical education for health professionals. However, students may not fully perceive the importance of these disciplines and therefore may not develop a sufficient level of competence. To facilitate learning and increase efficiency, 3D environments using augmented reality (AR) recently emerge as educational strategies. They seem to improve knowledge and create an environment conducive to learning. Therefore, we have developed an AR application that integrate anatomy and histology, based on anatomical reality, able to scalable and usable in hybrid teaching. Reference patient DICOM data were transformed into .obj formats using the 3D slicer software and imported into the blender, while zbrush, autodesk maya and substance software were used to optimize the skeleton, urinary cavities, and vascular structures. Bone images obtained by photogrammetry were superimposed on this reconstruction. To this basic structure, relevant anatomical and histological structures with a high degree of scientific fidelity have been integrated. A feasibility study was carried out to assess the technical aspects, the ways to introduce the app to the students and the potential for its implementation in educational strategies. First, a technical test was performed with 500 first-year medical students. From 202 respondents, 31% of them encountered technical difficulties mostly related to functionalities. We are nevertheless optimistic about the tool potential because almost half of the students (47% of respondents) have found it very useful to better visualize the 3D aspects and the relationships between organs. A second feasibility study investigated the tool handling. 41 second-year medical students were randomly assigned to three protocols: one totally autonomous, one autonomous after watching an explanatory video and another supervised by a teacher. The handling was evaluated by questions requiring the use of all the app functionalities. The most successful group is the one that used the explanatory video, followed by the accompanied group and then the working independently group. The survey showed that the students experienced technical difficulties to display the model (20%) and the observation levels (11%), to perform rotations (40%) and zooms (17%). The tool potential was underlined as 91% find the app useful. Aspects relating to anatomy and histology integration (34%), 3D visualization (28%) and topography (17%) are mentioned in the free answers. Several anatomical visualizations in the same tool, displaying areas of interest and superimposing histological images are estimated useful by all of the involved students (100%). Finally, 97% of students have a general positive opinion qualifying the app as promising, useful, fun, integrative, congruent with morphology courses. This view is tempered by difficulties related to technical stability. In conclusion, the difficulties encountered are explained by the fact that the tool is still in the optimization phase. The app potential was undeniably highlighted. The integration of anatomy and histology in the same learning tool is a real opportunity. Indeed, while most students approach anatomy as a compartmentalized memorization task, those who combine it with understanding, integration with other disciplines and visualization at different levels seems to have a better acquisition of knowledge. This aspect will be investigated in the future.

L'anatomie et l’histologie sont des pierres angulaires de l’enseignement préclinique au sein des institutions universitaires formant des professionnels de la santé. Cependant, les étudiants peuvent ne pas percevoir pleinement l’importance de ces disciplines en tant que composantes essentielles de leur formation et ne pas développer un niveau de compétence suffisant. Les séances de laboratoire sont souvent limitées et l’intégration des notions reste compliquée pour la majorité des étudiants. Pour faciliter leur apprentissage et gagner en efficacité, des environnements 3D utilisant la réalité augmentée apparaissent dans les stratégies éducatives émergentes. Dès lors, nous avons développé, ARanatomy, une application de réalité augmentée répondant aux exigences suivantes : intégré des notions d’anatomie et d’histologie, basé sur la réalité anatomique, capable d’évoluer et utilisable dans un enseignement hybride. ARanatomy associe des notions anatomiques du rétropéritoine et histologiques du système néphro-urinaire, de même que le squelette reconstitué en photogrammétrie et les données d’imagerie médicale correspondantes. Le potentiel de l’intégration de cette application a été évalué dans différentes scénarisations pédagogiques.

Dans ce rapport, les échanges d'information d'un donneur d'ordre, d'un transporteur et d'un fournisseur au sein d'une chaîne de distribution sont analysés. Les possibilités de tracking et de tracing de TransLogisTIC sont utilisés pour générer des KPI de performance et un modèle d'optimisation de quais de chargement est décrit dans une version Off-line et On-line.

Dans ce rapport confidentiel, un algorithme d'optimisation du chargement de véhicules a été mis au point dans le cadre d'une application avec un partenaire industriel.

Dans cette revue de la littérature scientifique, on peut trouver une synthèse des thématiques liées aux modèles et aux techniques d'optimisation utilés pour la gestion de ressources réutilisables dans un réseau tels que les containers entre des ports de mers ou des wagons dans un réseau ferroviaire. Les textes fondateurs sont mentionnés dans un ordre historique et un commentaire est fait soit sur le modèle investiqué et ses particularités ou la technique de résolution.