Contribution à l'optimisation globale pour le dimensionnement et la gestion d'énergie de véhicules hybrides électriques basée sur une approche combinatoire

Hybridization of power sources for embedded applications becomes an interesting solution to respect environmental legislation and achieve a higher energy efficiency. However, the choice for components sizing and the energy management strategy need to meet specifications while reducing costs. To solve this optimization problems including several types of variables can be complex because of non linearities included in the formulated problem. Therefore the use of effective solving tools, able to provide a reliable solution, is required. In this thesis, a global optimization method is proposed for the design and the optimal control of hybrid vehicles based on combinatorial optimization, particularly on integer linear programming. From a non-linear optimization problem, the initial problem is reformulated into a multitude of integer linear sub-problems for which a parallel Branch & Bound algorithm is executed. In order to solve large-scale problems, a second algorithm based on the Branch & Cut is developed. This method is used for the study of a hybrid power supply system of a mini-excavator electric. The optimization problem, where energy constraints and aging constraints are implemented, is evaluated according to several parameters and specifications. Finally, this approach is also applied for the optimization of trajectories for a synchronized multi-actuators system.L'hybridation des sources de puissance dans le domaine des applications embarquées s'est imposée comme une solution adéquate pour répondre aux législations environnementales et atteindre une meilleure efficacité énergétique. Toutefois, le choix dans le dimensionnement des composants et la stratégie de commande doivent répondre à un cahier des charges, souvent complexe et hétérogène, tout en limitant les coûts du système. La résolution de ce problème d'optimisation incluant de nombreuses variables peut s'avérer complexe à cause des non-linéarités présentes dans le problème formulé. Il faut donc disposer d'outils de résolution efficaces et capables de fournir une solution fiable. Dans cette thèse, nous proposons une méthode d'optimisation globale pour le dimensionnement et la commande optimale de véhicules hybrides basée sur l'optimisation combinatoire, et en particulier sur la programmation linéaire en nombres entiers (PLNE). A partir d'un problème d'optimisation non linéaire, le problème initial est reformulé en une multitude de sous-problèmes linéaires en nombres entiers sur lesquels un algorithme de Branch & Bound parallèle est exécuté. Afin de résoudre des problèmes de grande taille, un second algorithme basé sur le Branch & Cut est développé. Cette méthode est déployée pour l'étude d'un système d'alimentation hybride d'une mini-excavatrice électrique. Le problème d'optimisation, dans lequel des contraintes énergétiques et des contraintes de vieillissement sont implantées, est évalué suivant différents paramètres du cahier des charges. Enfin, cette approche est également appliquée pour l'optimisation de trajectoires d'un système multi-actionneur synchronisés

CortExTool: a toolbox for processing motor cortical excitability measurements by transcranial magnetic stimulation

Assessing motor cortical excitability (CE) is essential in transcranial magnetic stimulation (TMS) in order to ensure both safe and normalised stimulation power across subjects or patients. However, there is still a lack of automatic and easy-to-use tools for analysing the electromyographic (EMG) signal features that are relevant for CE assessment, such as the amplitude of motor evoked potentials (MEPs) or the duration of cortical silent periods (CSPs). Here, we describe CortExTool, a signal processing toolbox we developed to fulfil these needs. The toolbox, developed in the Matlab programming language, is open-source and freely accessible to the TMS community. CortExTool provides all the standard functionalities required to automatically process EMG signals recorded during a CE experiment, on both individual and group levels. Its use should allow to standardize and to facilitate the processing of CE measurements by TMS

Mapping dynamical properties of cortical microcircuits using robotized TMS and EEG: Towards functional cytoarchitectonics

International audienceBrain dynamics at rest depend on the large-scale interactions between oscillating cortical microcircuits arranged into macrocolumns. Cytoarchitectonic studies have shown that the structure of those microcircuits differs between cortical regions, but very little is known about interregional differences of their intrinsic dynamics at a macro-scale in human. We developed here a new method aiming at mapping the dynamical properties of cortical microcircuits non-invasively using the coupling between robotized transcranial magnetic stimulation and elec-troencephalography. We recorded the responses evoked by the stimulation of 18 cortical targets largely covering the accessible neocortex in 22 healthy volunteers. Specific data processing methods were developed to map the local source activity of each cortical target, which showed interregional differences with very good interhemi-spheric reproducibility. Functional signatures of cortical microcircuits were further studied using spatio-temporal decomposition of local source activities in order to highlight principal brain modes. The identified brain modes revealed that cortical areas with similar intrinsic dynamical properties could be distributed either locally or not, with a spatial signature that was somewhat reminiscent of resting state networks. Our results provide the proof of concept of " functional cytoarchitectonics " , that would guide the parcellation of the human cortex using not only its cytoarchitecture but also its intrinsic responses to local perturbations. This opens new avenues for brain modelling and physiopathology readouts

Brain Processing of Emotional Scenes in Aging: Effect of Arousal and Affective Context

International audienceResearch on emotion showed an increase, with age, in prevalence of positive information relative to negative ones. This effect is called positivity effect. From the cerebral analysis of the Late Positive Potential (LPP), sensitive to attention, our study investigated to which extent the arousal level of negative scenes is differently processed between young and older adults and, to which extent the arousal level of negative scenes, depending on its value, may contextually modulate the cerebral processing of positive (and neutral) scenes and favor the observation of a positivity effect with age. With this aim, two negative scene groups characterized by two distinct arousal levels (high and low) were displayed into two separate experimental blocks in which were included positive and neutral pictures. The two blocks only differed by their negative pictures across participants, as to create two negative global contexts for the processing of the positive and neutral pictures. The results show that the relative processing of different arousal levels of negative stimuli, reflected by LPP, appears similar between the two age groups. However, a lower activity for negative stimuli is observed with the older group for both tested arousal levels. The processing of positive information seems to be preserved with age and is also not contextually impacted by negative stimuli in both younger and older adults. For neutral stimuli, a significantly reduced activity is observed for older adults in the contextual block of low-arousal negative stimuli. Globally, our study reveals that the positivity effect is mainly due to a modulation, with age, in processing of negative stimuli, regardless of their arousal level. It also suggests that processing of neutral stimuli may be modulated with age, depending on negative context in which they are presented to. These age-related effects could contribute to justify the differences in emotional preference with age

Does face inversion change spatial frequency tuning?

International audienceThe authors examined spatial frequency (SF) tuning of upright and inverted face identification using an SF variant of the Bubbles technique (F. Gosselin & P. G. Schyns, 2001). In Experiment 1, they validated the SF Bubbles technique in a plaid detection task. In Experiments 2a-c, the SFs used for identifying upright and inverted inner facial features were investigated. Although a clear inversion effect was present (mean accuracy was 24% higher and response times 455 ms shorter for upright faces), SF tunings were remarkably similar in both orientation conditions (mean r = .98; an SF band of 1.9 octaves centered at 9.8 cycles per face width for faces of about 6 degrees ). In Experiments 3a and b, the authors demonstrated that their technique is sensitive to both subtle bottom-up and top-down induced changes in SF tuning, suggesting that the null results of Experiments 2a-c are real. The most parsimonious explanation of the findings is provided by the quantitative account of the face inversion effect: The same information is used for identifying upright and inverted inner facial features, but processing has greater sensitivity with the former

Multi-scale and cross-dimensional TMS mapping: A proof of principle in patients with Parkinson’s disease and deep brain stimulation

IntroductionTranscranial magnetic stimulation (TMS) mapping has become a critical tool for exploratory studies of the human corticomotor (M1) organization. Here, we propose to gather existing cutting-edge TMS-EMG and TMS-EEG approaches into a combined multi-dimensional TMS mapping that considers local and whole-brain excitability changes as well as state and time-specific changes in cortical activity. We applied this multi-dimensional TMS mapping approach to patients with Parkinson’s disease (PD) with Deep brain stimulation (DBS) of the sub-thalamic nucleus (STN) ON and OFF. Our goal was to identifying one or several TMS mapping-derived markers that could provide unprecedent new insights onto the mechanisms of DBS in movement disorders.MethodsSix PD patients (1 female, mean age: 62.5 yo [59–65]) implanted with DBS-STN for 1 year, underwent a robotized sulcus-shaped TMS motor mapping to measure changes in muscle-specific corticomotor representations and a movement initiation task to probe state-dependent modulations of corticospinal excitability in the ON (using clinically relevant DBS parameters) and OFF DBS states. Cortical excitability and evoked dynamics of three cortical areas involved in the neural control of voluntary movements (M1, pre-supplementary motor area – preSMA and inferior frontal gyrus – IFG) were then mapped using TMS-EEG coupling in the ON and OFF state. Lastly, we investigated the timing and nature of the STN-to-M1 inputs using a paired pulse DBS-TMS-EEG protocol.ResultsIn our sample of patients, DBS appeared to induce fast within-area somatotopic re-arrangements of motor finger representations in M1, as revealed by mediolateral shifts of corticomuscle representations. STN-DBS improved reaction times while up-regulating corticospinal excitability, especially during endogenous motor preparation. Evoked dynamics revealed marked increases in inhibitory circuits in the IFG and M1 with DBS ON. Finally, inhibitory conditioning effects of STN single pulses on corticomotor activity were found at timings relevant for the activation of inhibitory GABAergic receptors (4 and 20 ms).ConclusionTaken together, these results suggest a predominant role of some markers in explaining beneficial DBS effects, such as a context-dependent modulation of corticospinal excitability and the recruitment of distinct inhibitory circuits, involving long-range projections from higher level motor centers and local GABAergic neuronal populations. These combined measures might help to identify discriminative features of DBS mechanisms towards deep clinical phenotyping of DBS effects in Parkinson’s Disease and in other pathological conditions

Microsaccades are modulated by both attentional demands of a visual discrimination task and background noise

Microsaccades are miniature saccades occurring once or twice per second during visual fixation. While microsaccades and saccades share similarities at the oculomotor level, the functional roles of microsaccades are still debated. In this study, we examined the hypothesis that the microsaccadic activity is affected by the type of noisy background during the execution of a particular discrimination task. Human subjects had to judge the orientation of a tilted stimulus embedded in static or dynamic backgrounds in a forced choice-task paradigm, as adapted from Rucci, Iovin, Poletti, and Santini (2007). Static backgrounds induced more microsaccades than dynamic ones only during the execution of the discrimination task. A directional bias of microsaccades, dictated by the stimulus orientation, was temporally coupled with this period of increased activity. Both microsaccade rates and orientations were comparable across background types after the response time although subjects maintained fixation until the end of the trial. This represents a background-specific modulation of the microsaccadic activity driven by attentional demands. The visual influence of microsaccades on discrimination performances was modeled at the retinal level for both types of backgrounds. A higher simulated microsaccadic activity was necessary for static backgrounds in order to achieve discrimination performance scores comparable to that of dynamic ones. Taken together, our experimental and theoretical findings further support the idea that microsaccades are under attentional control and represent an efficient sampling strategy allowing spatial information acquisition

Contribution to global optimization for the sizing and energy management of hybrid electric vehicles based on a combinatorial approach

L'hybridation des sources de puissance dans le domaine des applications embarquées s'est imposée comme une solution adéquate pour répondre aux législations environnementales et atteindre une meilleure efficacité énergétique. Toutefois, le choix dans le dimensionnement des composants et la stratégie de commande doivent répondre à un cahier des charges, souvent complexe et hétérogène, tout en limitant les coûts du système. La résolution de ce problème d'optimisation incluant de nombreuses variables peut s'avérer complexe à cause des non-linéarités présentes dans le problème formulé. Il faut donc disposer d'outils de résolution efficaces et capables de fournir une solution fiable. Dans cette thèse, nous proposons une méthode d'optimisation globale pour le dimensionnement et la commande optimale de véhicules hybrides basée sur l'optimisation combinatoire, et en particulier sur la programmation linéaire en nombres entiers (PLNE). A partir d'un problème d'optimisation non linéaire, le problème initial est reformulé en une multitude de sous-problèmes linéaires en nombres entiers sur lesquels un algorithme de Branch & Bound parallèle est exécuté. Afin de résoudre des problèmes de grande taille, un second algorithme basé sur le Branch & Cut est développé. Cette méthode est déployée pour l'étude d'un système d'alimentation hybride d'une mini-excavatrice électrique. Le problème d'optimisation, dans lequel des contraintes énergétiques et des contraintes de vieillissement sont implantées, est évalué suivant différents paramètres du cahier des charges. Enfin, cette approche est également appliquée pour l'optimisation de trajectoires d'un système multi-actionneur synchronisés.Hybridization of power sources for embedded applications becomes an interesting solution to respect environmental legislation and achieve a higher energy efficiency. However, the choice for components sizing and the energy management strategy need to meet specifications while reducing costs. To solve this optimization problems including several types of variables can be complex because of non linearities included in the formulated problem. Therefore the use of effective solving tools, able to provide a reliable solution, is required. In this thesis, a global optimization method is proposed for the design and the optimal control of hybrid vehicles based on combinatorial optimization, particularly on integer linear programming. From a non-linear optimization problem, the initial problem is reformulated into a multitude of integer linear sub-problems for which a parallel Branch & Bound algorithm is executed. In order to solve large-scale problems, a second algorithm based on the Branch & Cut is developed. This method is used for the study of a hybrid power supply system of a mini-excavator electric. The optimization problem, where energy constraints and aging constraints are implemented, is evaluated according to several parameters and specifications. Finally, this approach is also applied for the optimization of trajectories for a synchronized multi-actuators system

Perception des scènes naturelles (étude et simulation du rôle de l'amplitude, de la phase et de la saillance dans la catégorisation et l'exploration de scènes naturelles)

GRENOBLE1-BU Sciences (384212103) / SudocVILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceF

Lecture et exploration oculaire : intégration du texte et de l’image

a nécessité contemporaine d interagir avec l information numérique sous toutes ses formes rend prégnant tout questionnement lié à la visualisation d information. Information & Visualisation rassemble des approches disciplinaires différentes autour de la visualisation de données interactives afin d entrevoir les perspectives dont elle est porteuse. Cet ouvrage fait non seulement appel à un ensemble de courants de recherche actuels mais aussi aux applications professionnelles et industrielles de la visualisation d information. Les éléments complémentaires de bibliographie proposés permettront de prolonger la réflexion. Dans le contexte de la visualisation des informations, la pluridisciplinarité permet d envisager une ergonomie informationnelle qui amplifie la perception, la compréhension et l usage de l information interactive en des formes visuelles signifiantes. C est dans cette perspective que cet ouvrage fait converger des éclairages venus de la psychophysique, des technologies de l information et de leurs processus d apprentissage, des mathématiques statistiques et algorithmiques, de l évaluation de l activité de recherche d information, de la sémiologie graphique, de la cartographie, et des expérimentations d art numérique. Les problématiques de visualisation ici traitées s appliquent sur des situations d usages diversifiées qui vont de pratiques artistiques, à la recherche d information, aux échanges dans le cadre de réseaux sociaux, à la cartographie de connaissances. Le lecteur trouvera ici des approches complémentaires. Celles-ci tendent à favoriser les échanges interdisciplinaires qui visent à rendre plus efficients les outils de médiation et de cognition que génère la pratique de visualisation d information