Scientific Publications of the University of Toulouse II Le Mirail
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Data-driven queueing modelling: a simulation case study of emergency department crowding
No full textInternational audienceObjectives Emergency department crowding refers to a complex state of congestion associated with a set of performance indicators such as occupation levels, waiting times and specific scores. Among current methods to model it, an objective gap exists between forecasting machine learning methods, focusing on prediction precision and queueing and simulation methods, focusing on capturing correctly the effect of decision variables for evaluation and optimisation purposes. The objective of the present analysis is to implement and numerically validate a novel data-driven queueing methodology that can bridge this gap and to show its applicability in a simulation case study. Methods A statistical modelling of the queueing processes, particularly patient departure rates and probabilities, is developed to cross the gap defined above. Using the data from a major emergency department of eastern France, the resultant data-driven queueing network model is validated and applied through a synchronous simulation algorithm. Results The model obtained considers the complex effects of patient arrivals and doctor and nurse allocations while offering an unbiased and accurate measure of long-term crowding. Its application with the case study quantifies the impact of the opening of new Unscheduled Care Services on emergency department crowding. Discussion The new data-driven queueing methodology is able to model and quantify complex crowding effects at a detailed level in an emergency department. Conclusions This study shows an alternative approach successfully bridging the modelling gap by establishing a model that can effectively predict system crowding dynamics under the influence of multiple key variables
Analyse didactique de la pertinence d’un dispositif de formation visant à développer une démarche réflexive chez les professeurs des écoles stagiaires
No full textInternational audienceThe main aim of this research article is to demonstrate the relevance and appropriateness of a classroom visit by a trainee primary school teacher in France. The visit is structured around three phases: observation by a trainer of the implementation of a situation by a trainee primary school teacher, post-observation interview, production of a post-interview reflective piece of writing. The methodology is based, on the one hand, on the analysis of the interview that follows the classroom observation and, on the other, on the study of the professional writing drafted by the trainee. Throughout the analysis of the system, the aim is to detect changes in the trainee teacher's posture, and thus to highlight the trainee's ability to adopt a reflective posture in terms of how he or she brings his or her pupils to experience a mathematical situation.Cet article de recherche a pour principale finalité de montrer la pertinence et la cohérence d’un dispositif spécifique de visite en classe d’un enseignant stagiaire au primaire. Ce dispositif s’articule en trois temps : observation par un formateur de la mise en œuvre d’une situation mathématique par un professeur des écoles stagiaire, entretien post-observation, production d’un écrit réflexif post-entretien. La méthodologie repose d’une part sur l’analyse de l’entretien qui fait suite à l’observation de classe, d’autre part sur l’étude de l’écrit professionnel rédigé par le stagiaire. Il s’agit tout au long de l’analyse du dispositif de déceler les changements d’attitude de l’enseignant stagiaire et ainsi de mettre en lumière sa capacité à adopter une démarche réflexive quant à sa manière de faire vivre une situation mathématique à ses élèves
Contact-Robust Trajectory Planning via Parametric Sensitivity Analysis for Hybrid Robotic Systems
No full textInternational audienceIn this paper, we combine first-order approximations of hybrid systems (i.e., the so-called saltation matrix) with previous works on parametric sensitivity for continuous systems to propose a general framework for robust trajectory optimization of hybrid systems subject to parametric uncertainties. A method for computing parametric sensitivities of both continuous dynamics and hybrid events is presented. The obtained "hybrid parametric sensitivity" is then combined with sensitivity-based tubes that encapsulate all possible perturbed states and control trajectories given a known bounded range for the uncertain parameters. The proposed method is then applied to the problem of planning robust trajectories for legged robot systems, which allows obtaining trajectories that remain feasible w.r.t. the contact constraints even in presence of uncertainties in the dynamics, guard conditions, and reset maps. We also illustrate one of the fundamental limitations of first-order approximations, that is, the fact that the sensitivity reset time is fixed, and propose an extension to the sensitivity analysis that can form the basis for future developments
Predictors of brain death after hanging-induced cardiac arrest
No full textInternational audienceBrain death after hanging-induced cardiac arrest is a fatal complication about which few data are available. We aimed at identifying the early predictors of progression to brain death in patients with hanging-induced cardiac arrest
From the block to the blade: The contribution of lithic technology of the Villazette site (Creysse, Dordogne) to understanding the early stages of blade production in the Middle Magdalenian
No full textInternational audienceIn southwestern France, blades attributed to the Late Middle Magdalenian are occasionally found in the form of batches of finished objects in particular contexts such as painting cave like Labastide or Enlène in the Pyrenees. The lack of first stages of production, absent or poorly documented in “consumption” sites, represent a key obstacle to fully understand the chaîne opératoire. As such, investigating a lithic assemblage from “production” sites through refitting and technological analysis raises questions about technological segmentation of blade production.Located in the Aquitaine Basin, the site of Villazette (Creysse, Dordogne) is situated on the low terraces of the Dordogne River, in an area rich in high-quality ‘Bergeracois’ flint. Excavations have revealed a series of open-air occupations, including one layer related to the Late Middle Magdalenian phase showing evidence of blade production.The analysis of cores and other products confirms the presence of blades exceeding twenty centimeters, along with the production of smaller blades for toolmaking. Refitting studies provide insight into the early stages of blade production: raw blocks were collected on-site and shaped through the preparation of anterior and posterior crests, ensuring an efficient reduction sequence.Furthermore, the spatial distribution analysis reveals two concentrations with distinct functions, raising questions about the organization of the occupation. The discovery of this site underscores the archaeological potential of the Dordogne’s riverbanks for exploring the organization of Magdalenian groups
Bilevel gradient methods and the Morse parametric qualification condition
No full textInternational audienceWe introduce the Morse parametric qualification condition for bilevel programming. Generic semi-algebraic functions are Morse parametric in a piecewise sense. Thus, bilevel programs with a Morse parametric lower level constitute a relevant intermediate class between strongly convex and fully generic lower levels. In this framework, we study bilevel gradient algorithms with two strategies: the single-step multi-step strategy, which involves a sequence of steps on the lower-level problems followed by one step on the upper-level problem, and a differentiable programming strategy that optimizes a smooth approximation of the bilevel problem. While the first is shown to be a biased gradient method on the problem with rich properties, the second, inspired by meta-learning applications, is less stable but offers simplicity and ease of implementation
An iterative CP approach for handling min/max worload constraints in preemptive JSP
No full textInternational audienceAn iterative CP approach for handling min/max worload constraints in preemptive JS
The evolution of the cave's entrance of Bruniquel and consequences for its accessibility by early Homo neanderthalensis
No full textInternational audienceThe cave of Bruniquel, discovered by cavers in 1990, contains the oldest evidence of deep cave use by early Homo neanderthalensis. The discovery and dating of speleothem-based structures and fireplaces demonstrated their ability to investigate the deep subterranean environment in a structured way (Jaubert et al., 2016). The cave has been closed by a succession of rockfalls, flowstone layers and scree cone deposits, which led to the preservation of multiple traces of human and animal activity inside the cave. We studied the cave entrance evolution through a multidisciplinary integrated geomorphological approach, combining 3D surveys inside and outside the cave system, high-resolution geomorphological mapping, Electrical Resistivity Tomography (ERT), and U-series dating. The combination of stratigraphic surveys and U-series dating allowed us to date the closure of the cave to before 142.9 ± 1.3 ka, before the Last Interglacial, thus independently confirming the age of the speleothem structures and of the other traces observed on the cave floor. The proposed virtual 3D reconstruction of the palaeo-cave entrance at the beginning of MIS 6, suggests an entrance less than 2 m high, implying that the space behind the entrance was rapidly dark. This work highlights the central importance of understanding the evolution of cave entrances for constraining the timing and the modalities of use of cave systems and provides a new palaeogeographic framework for future studies of the cave's occupation by early Homo neanderthalensis
Exact Functional ANOVA Decomposition for Categorical Inputs Models
No full textFunctional ANOVA offers a principled framework for interpretability by decomposing a model’s prediction into main effects and higher-order interactions. For independent features, this decomposition is well-defined, strongly linked with SHAP values, and serves as a cornerstone of additive explainability. However, the lack of an explicit closed-form expression for general dependent distributions has forced practitioners to rely on costly sampling-based approximations. We completely resolve this limitation for categorical inputs. By bridging functional analysis with the extension of discrete Fourier analysis, we derive a closed-form decomposition without any assumption. Our formulation is computationally very efficient. It seamlessly recovers the classical independent case and extends to arbitrary dependence structures, including distributions with non-rectangular support. Furthermore, leveraging the intrinsic link between SHAP and ANOVA under independence, our framework yields a natural generalization of SHAP values for the general categorical setting
Electro-Thermo-Optical Modulation of Silicon Nitride Integrated Photonic Filters for Analog Applications
No full textInternational audienceHigh-quality spectral filters with versatile tuning mechanisms are essential for applications in photonic integrated circuits, including sensing, laser stabilization, and spectral signal processing. We report the implementation of thermo-optic (TO) and electro-optic (EO) spectral tuning in silicon nitride Mach–Zehnder interferometers (MZIs) and micro-ring resonators (MRRs) by functionalizing the devices with a PMMA:JRD1 polymer cladding and integrating titanium tracks as heaters and electrodes. The fabricated MZIs and MRRs exhibit narrow linewidths of 25–30 pm and achieved TO tuning efficiencies of 1.7 and 13 pm/mW and EO tuning efficiencies of 0.33 and 1.6 pm/V, respectively. Closed-loop regulation using TO and EO effects enables stable half-fringe locking under environmental perturbations. This simple, broadly compatible hybrid platform demonstrates a practical approach to dual-mode spectral tuning and modulation in integrated photonic filters, providing a flexible route toward compact, reconfigurable, and environmentally robust photonic circuits