Plates-formes et mises à jour dynamiques configurables

Dynamic software updating allows applications to be modified without interrupting the services it provides. Because today's systems rely heavily on software and its availability, such a possibility is an important issue. Many mechanisms with diverse needs and properties enable dynamic updates. They are used by platforms targeting specific types of applications and/or updates. While the specialization of these platforms make the development of dynamic updates easier, it can cause the platform to be ill suited in the case of unforeseen updates. A solution is to select and combine best-suited mechanisms for each update in order to guarantee a best compatibility of platforms with the different kinds of applications and updates. The three contributions detailed in this thesis follow this objective: - Studying platforms and identify generic models for platforms and updates - Studying the needs and properties of mechanisms as well as their capacity to be combined - Develop configurable platforms allowing the selection of best-suited mechanisms for each update. Theses contributions open leads towards a new generation of platforms and towards new uses of dynamic updates. The third contribution lead to the development of Pymoult, a configurable platform for Python programs. Pymoult provides several mechanisms through a high-level API suited to the conception of dynamic updates.La mise à jour dynamique des logiciels permet de modifier ces derniers sans interrompre les services qu'ils fournissent. C'est un enjeu important à une époque où les logiciels sont omniprésents et où leur indisponibilité peut être coûteuse (service commercial) ou même dangereuse (système de sécurité). De nombreux mécanismes aux propriétés et besoins variés permettent d'atteindre cet objectif. Ces mécanismes sont employés par des plates-formes dédiées à des types de logiciel et/ou de mises à jour spécifiques. En se spécialisant, ces plates-formes facilitent l'écriture de mises à jour dynamiques mais peuvent être mal adaptées à l'application de certaines modifications imprévues. Il convient alors de sélectionner et combiner les mécanismes les mieux adaptés à chaque mise à jour afin d'assurer une meilleure compatibilité des plates-formes avec les différents logiciels et mises à jour. C'est autour de cet objectif que s'organisent les contributions de ce manuscrit: - Étudier les plates-formes et identifier des modèles génériques de plate-forme et de mise à jour - Étudier les besoins et les propriétés des mécanismes de mise à jour ainsi que leurs capacités à être combinés. - Développer des plates-formes configurables permettant de sélectionner les mécanismes les mieux adaptés pour chaque mise à jour. Les résultats obtenus ouvrent des pistes vers une nouvelle génération de plates-formes ainsi que vers de nouvelles utilisations de la mise à jour dynamique. Le troisième axe a mené au développement de Pymoult, plate-forme configurable pour programmes Python. Cette plate-forme fournit de nombreux mécanismes au travers d'une API de haut niveau adaptée à la conception de mises à jour dynamiques

Robust fault detection for Uncertain Unknown Inputs LPV system

International audienceThis paper focuses on robust fault residual generation for Uncertain Unknown Inputs Linear Parameter Varying (U-LPV) systems. Firstly, the problem is addressed in standard LPV systems based on the adaptation of the parity-space approach. The main objective of this approach is to design a scheduled parity matrix according to the scheduling parameters. It results a perfectly decoupled parity matrix face to the system states. Then, the major contribution of this paper relies on the extension to U-LPV systems. Since most of models which represent practical/real systems are subject to parameters variation, unmodeled dynamics and unknown inputs, the approach is clearly justified. The residual synthesis is rewritten in terms of a new optimization problem and solved using Linear Matrix Inequalities (LMIs) techniques. An applicative illustration is proposed and rests on a vehicle lateral dynamic system

Attentional filtering of visual information by neuronal ensembles in the primate lateral prefrontal cortex.

The activity of neurons in the primate lateral prefrontal cortex (LPFC) is strongly modulated by visual attention. Such a modulation has mostly been documented by averaging the activity of independently recorded neurons over repeated experimental trials. However, in realistic settings, ensembles of simultaneously active LPFC neurons must generate attentional signals on a single-trial basis, despite the individual and correlated variability of neuronal responses. Whether, under these circumstances, the LPFC can reliably generate attentional signals is unclear. Here, we show that the simultaneous activity of neuronal ensembles in the primate LPFC can be reliably decoded to predict the allocation of attention on a single-trial basis. Decoding was sensitive to the noise correlation structure of the ensembles. Additionally, it was resilient to distractors, predictive of behavior, and stable over weeks. Thus, LPFC neuronal ensemble activity can reliably encode attention within behavioral time frames, despite the noisy and correlated nature of neuronal activity

Fault Tolerant Strategy for Semi-Active Suspensions with LPV Accommodation

International audienceAbstract--A novel fault tolerant strategy to compensate multiplicative actuator faults (damper oil leakages) in a semiactive suspension system is proposed. The compensation of the lack of damping force caused by a faulty damper is carried on by the remainder three healthy semi-active dampers. Once a faulty damper is detected and isolated by a Fault Detection and Isolation strategy based on parity-space, an estimator is activated to compute the missing damping force to compensate. In order to fulfill the semi-active damper constraints, the fault accommodation is based on the Linear-Parameter Varying (LPV) control strategy. Thus, each corner has a fault estimator and an LPV controller oriented to comfort and road holding. Simulation results show that the proposed fault tolerant semiactive suspension improves the vehicle comfort up to 60% with respect to a controlled suspension without fault-tolerant strategy and 82% with respect to a passive suspension

IVOA Recommendation: An IVOA Standard for Unified Content Descriptors Version 1.1

This document describes the current understanding of the IVOA controlled vocabulary for describing astronomical data quantities, called Unified Content Descriptors (UCDs). The present document defines a new standard (named UCD1+) improving the first generation of UCDs (hereafter UCD1). The basic idea is to adopt a new syntax and vocabulary requiring little effort for people to adapt softwares already using UCD1. This document also addresses the questions of maintenance and evolution of the UCD1+. Examples of use cases within the VO, and tools for using UCD1+ are also described

The effects of methylphenidate (Ritalin) on the neurophysiology of the monkey caudal prefrontal cortex

© 2019 Tremblay et al. Methylphenidate (MPH), commonly known as Ritalin, is the most widely prescribed drug worldwide to treat patients with attention deficit disorders. Although MPH is thought to modulate catecholamine neurotransmission in the brain, it remains unclear how these neurochemical effects influence neuronal activity and lead to attentional enhancements. Studies in rodents overwhelmingly point to the lateral prefrontal cortex (LPFC) as a main site of action of MPH. To understand the mechanism of action of MPH in a primate brain, we recorded the responses of neuronal populations using chronic multielectrode arrays implanted in the caudal LPFC of two macaque monkeys while the animals performed an attention task (N 2811 neuronal recordings). Over different recording sessions (N 55), we orally administered either various doses of MPH or a placebo to the animals. Behavioral analyses revealed positive effects of MPH on task performance at specific doses. However, analyses of individual neurons activity, noise correlations, and neuronal ensemble activity using machine learning algorithms revealed no effects of MPH. Our results suggest that the positive behavioral effects of MPH observed in primates (including humans) may not be mediated by changes in the activity of caudal LPFC neurons. MPH may enhance cognitive performance by modulating neuronal activity in other regions of the attentional network in the primate brain

Fault Tolerant Control with Additive Compensation for Faults in an Automotive Damper

International audienceAbstract--A novel Fault-Tolerant Controller is proposed for an automotive suspension system based on a Quarter of Vehicle (QoV) model. The design is divided in a robust Linear Parameter-Varying controller used to isolate vibrations from external disturbances and in a compensation mechanism used to accommodate actuator faults. The compensation mechanism is based on a robust fault detection and estimation scheme that reconstructs a fault on the semi-active damper; this information is used to reduce the failure effect into the vertical dynamics to achieve good control performances. Validations have been made over a QoV model in CarSimTM. Results show the effectiveness of the faulttolerant semi-active damper versus an uncontrolled damper; the improvement is 50.4% in comfort and 42.4% in road holding, by avoiding biases in the damper deflection

Software assembly and open standards for driving simulation

International audienceDriving simulation systems involve a combination of different computation codes. Although some of these modules are application-specific, their majority is reusable and state-of-the-art implementations are readily available in the open source community. This study investigates whether these open source libraries can combine to build a driving simulation application with reasonable performance. To this end, a component-oriented architecture is proposed, in which modules encapsulate relevant libraries behind a standard interface and exchange simulation data through a message passing interface. By integrating a render engine, a physics library and a simple vehicle dynamics model, we were able to rapidly build a functional minimal simulation application supporting distributed execution over a cluster of computers. As this architecture allows the transparent modification of module code and simplifies the addition of new modules, this kernel represents the foundations of an extensible and reconfigurable open source system dedicated to driving simulation. Details on this kernel application and ongoing development of this platform can found at http://open-s.sourceforge.net.Les logiciels de simulation de conduite reposent sur une combinaison de différents codes de calculs. Bien qu’une partie de ces modules soit extrêmement dépendante d’un usage particulier, leur majorité est réutilisable et certaines implémentations de pointe sont disponibles dans la communauté du logiciel libre. Cette étude vise à déterminer s’il est possible de combiner ces bibliothèques libres afin de construire une application de simulation de conduite atteignant de raisonnables performances. A cette fin, nous proposons une architecture orientée composant, selon laquelle ces bibliothèques sont encapsulées dans des modules s’échangeant des données relatives à la simulation au travers d’une interface d’échange de messages. En intégrant à cette architecture un moteur graphique, une bibliothèque de simulation de physique et un simple modèle de dynamique de véhicule, nous avons pu rapidement mettre en place une application de simulation minimale, pouvant s’exécuter de manière distribuée sur un cluster d’ordinateurs. Cette architecture permettant de modifier le code d’un module de manière transparente et simplifiant l’ajout de nouveaux modules, ce noyau constitue la base d’un logiciel libre extensible et polymorphique dédié à la simulation de conduite dont les détails peuvent être consultés sur le site : http://open-s.sourceforge.net

Software assembly and open standards for driving simulation

Driving simulation systems involve a combination of different computation codes. Although some of these modules are application-specific, their majority is reusable and state-of-the-art implementations are readily available in the open source community. This study investigates whether these open source libraries can combine to build a driving simulation application with reasonable performance. To this end, a component-oriented architecture is proposed, in which modules encapsulate relevant libraries behind a standard interface and exchange simulation data through a message passing interface. By integrating a render engine, a physics library and a simple vehicle dynamics model, we were able to rapidly build a functional minimal simulation application supporting distributed execution over a cluster of computers. As this architecture allows the transparent modification of module code and simplifies the addition of new modules, this kernel represents the foundations of an extensible and reconfigurable open source system dedicated to driving simulation. Details on this kernel application and ongoing development of this platform can found at http://open-s.sourceforge.net.Les logiciels de simulation de conduite reposent sur une combinaison de différents codes de calculs. Bien qu’une partie de ces modules soit extrêmement dépendante d’un usage particulier, leur majorité est réutilisable et certaines implémentations de pointe sont disponibles dans la communauté du logiciel libre. Cette étude vise à déterminer s’il est possible de combiner ces bibliothèques libres afin de construire une application de simulation de conduite atteignant de raisonnables performances. A cette fin, nous proposons une architecture orientée composant, selon laquelle ces bibliothèques sont encapsulées dans des modules s’échangeant des données relatives à la simulation au travers d’une interface d’échange de messages. En intégrant à cette architecture un moteur graphique, une bibliothèque de simulation de physique et un simple modèle de dynamique de véhicule, nous avons pu rapidement mettre en place une application de simulation minimale, pouvant s’exécuter de manière distribuée sur un cluster d’ordinateurs. Cette architecture permettant de modifier le code d’un module de manière transparente et simplifiant l’ajout de nouveaux modules, ce noyau constitue la base d’un logiciel libre extensible et polymorphique dédié à la simulation de conduite dont les détails peuvent être consultés sur le site : http://open-s.sourceforge.net