Thèses sur le sujet « Body localisation »

People are generally quite good at adapting to changes in body shape and size because of the flexibility of the body representation. By means of bodily illusions, it is possible to experimentally induce updating of body representation and, thus, manipulate the sense of self. The main aim of this thesis is to investigate the sense of self through bodily illusions. Firstly, we investigated the relationship between the sense of ownership and self-localisation (Study 1). The results from this study are taken to suggest that the proprioceptive drift (i.e. a bias in the localisation of a given body part) is more likely triggered by and related to the visual capture of touch than it is a reliable measure of a shift in the sense of body ownership. In fact, our data show that the proprioceptive drift occurs not only in the absence of a shift in the sense of ownership, but even in the absence of a body-like object. Secondly, we investigated self-localisation of body parts by means of a novel illusion, the Disappearing Hand Trick. In particular, we explored the role of vision and proprioception (Study 2), as well as the role of attention and motor acts (Study 3), in locating one’s own hands when visual and proprioceptive information regarding the body are incongruent. Our data (Study 2) are in line with previous research, confirming a predominant role of vision over proprioception. In addition, they show that, after a certain amount of time, proprioception is weighted more heavily than vision. That is, our results demonstrate that the cortical proprioceptive representations can be updated even when there is no real need to do it (i.e. no movement is required). This might be seen as an evolutionarily convenient response to keep the body ready for a possible quick reaction. In Study 3, we ruled out the possibility that this effect was only driven by spatial attention being directed towards the side of the space where the hand was actually located. In fact, no difference in the localisation accuracy was found when the direction of spatial attention was manipulated. Finally, by asking the participants to reach across for their hidden right hand (Study 3), we confirmed that a motor act accelerates the reliance on proprioception, most likely by aligning the motor and perceptual coordinates in order to plan the movement. In the first three studies, a modification of the body representation was intentionally induced – namely, the purpose of the illusions was to change how the participants perceived their body. However, we wondered whether this same change might also occur at a more implicit level and how rapidly this may occur. We designed two different studies in which we tried to manipulate the participants’ perceived body size by providing incongruent information about the position of their limb (Study 4) or by showing the participants images of unrealistic bodies (Study 5). In Study 4 we showed that incongruent proprioceptive information coming from the same joint does not affect the perceived size of that body part, but does lead to a more accurate estimation of its position. On the other hand, the results of Study 5 would seem to suggest that body perception is more vulnerable to change in women than in men after exposure to same-sex ideal bodies. Taken together, these results suggest that, by manipulating the body representation, both explicitly, by means of a variety of bodily illusion, and even implicitly, by generating subtle incongruence between one’s own real body and how the body ‘should’ be, we were able to shed some light on the mechanisms behind the computation of body position and size, both of which are important elements for the definition of the self.

Engineering advancement over the last decade has significantly benefited the medical field, facilitating personalised and accessible healthcare. Various portable systems have been developed to obtain diagnostic parameters without the necessity for sedation or immobilisation of the patient, and even their presence at the medical facility. This can be especially important for populations that are at greater medical risk and are unable to undergo sedation, as well as for overall screening of the underlying conditions by continuous monitoring. This thesis provides engineering solutions aimed at improving the reliability of one of the modern medical diagnostic techniques – Wireless Capsule Endoscopy (WCE). It is a non-invasive approach for gastrointestinal (GI) tract examination that involves the natural propagation of a capsule through the entire tract of the patient while recording images of the lining. The video data are transmitted to a receiving unit outside the body, which is then accessed by medical practitioners for appropriate diagnostics. The Wireless Body Area Network (WBAN) technology describes the acquisition and transmission of the signal. One of the major challenges associated with WCE is the accurate localisation of the capsule due to the transit time being different for each individual. Localisation methods based on various physical principles are still under investigation by researchers. In this study, radiofrequency (RF) signal propagation analysis was used to provide accurate received signal strength (RSSI)-based localisation of the wireless endoscopy capsule. RSSI-based methods are widely used in indoor and outdoor positioning systems, allowing the estimation of the radial distance between reference sensors and an unknown transmitter position. Due to the significantly different electromagnetic (EM) properties of the human body as a propagation medium compared to air, one of the main objectives of this work was to develop an appropriate path loss propagation model. The advantage of the proposed solution is that it is based on an analytical approach and includes the attenuation constant defined by the EM properties of the soft tissues in the abdominal area. The theoretical basis of the developed attenuation path loss model (APLM) can be used to generalise and implement it for various In-to-On-Body communication systems at different operational frequencies. The APLM was numerically validated using CST Studio Software©, as well as by experiments on ex-vivo porcine tissues and in-vivo measurements on anesthetised living pigs. The experiments also served as the iii performance validation of a receiving inward cavity-backed slot antenna designed specifically for In-to-On-Body communications at 2.45 GHz, ISM band. In-vivo trials included implanting a wireless transmitter at several abdominal positions, which were then used for the 2-D and 3-D localisation accuracy assessment. Two trials were conducted separately at the medical facilities of The University of Southern Denmark (Odense, Denmark) and at the Herston Medical Research Centre, The University of Queensland (Brisbane, QLD, Australia). The research presents new knowledge for WBAN channel modelling for propagation media similar to the human body; confirms the reliability of the slot antenna performance for surface field measurements in WCE applications at 2.45 GHz; validates the application of the attenuation path loss model for In-to-On-Body communication channels; and it demonstrates high localisation accuracy when the proposed attenuation path loss model is used as an inverse solution for finding radial distances between the reference sensor and the unknown implant position.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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Au sein de physique des systèmes quantiques désordonnés, le domaine des atomes ultra-froids est en pleine croissance. En l’occurrence, l'étude de la relation entre la localisation et les interactions a permis de découvrir la richesse de la physique de la localisation à N-corps. Ce phénomène remarquable fournit un mécanisme pour la brisure de l'ergodicité dans les systèmes quantiques isolés et désordonnés. Plusieurs questions ont été évoquées après cette découverte, comme la possibilité d'une transition fluide-isolant à température finie. Dans cette thèse, j'étudie la localisation à N-corps dans le contexte de bosons désordonnés à deux dimensions. Dans la première partie, je présente l'étude d'un gaz interactif de Bose bidimensionnel dans un potentiel aléatoire à température finie. Le système présente deux transitions à température finie: la transition de localisation à N-corps entre fluide et isolant, et la transition de Berezinskii-Kosterlitz-Thouless entre superfluide algébrique et fluide. J'examine ensuite l'influence de la troncature de la distribution d'énergie dû au piégeage, un phénomène générique dans le cadre du refroidissement d'atomes ultra-froids. Finalement, je conclus en discutant la stabilité de la phase isolante dans des systèmes définis sur un continuum
The study of the interplay between localization and interactions in disordered quantum systems led to the discovery of the interesting physics of many-body localization (MBL). This remarkable phenomenon provides a generic mechanism for the breaking of ergodicity in quantum isolated systems, and has stimulated several questions such as the possibility of a finite-temperature fluid-insulator transition. At the same time, the domain of ultracold interacting atoms is a rapidly growing field in the physics of disordered quantum systems. In this thesis, we study many-body localization in the context of two-dimensional disordered ultracold bosons. After reviewing some importance concepts, we present a study of the phase diagram of a two-dimensional weakly interacting Bose gas in a random potential at finite temperatures. The system undergoes two finite-temperature transitions: the MBL transition from normal fluid to insulator and the Berezinskii-Kosterlitz-Thouless transition from algebraic superfluid to normal fluid. At T=0, we show the existence of a tricritical point where the three phases coexist. We also discuss the influence of the truncation of the energy distribution function at the trap barrier, a generic phenomenon for ultracold atoms. The truncation limits the growth of the localization length with energy and, in contrast to the thermodynamic limit, the insulator phase is present at any temperature. Finally, we conclude by discussing the stability of the insulating phase with respect to highly energetic particles in systems defined on a continuum

Dans le cadre de cette thèse, on se proposait de développer de nouveaux mécanismes de radiolocalisation, permettant de positionner les nœuds de réseaux corporels sans-fil (WBAN) mobiles, en exploitant de manière opportuniste des liens radio coopératifs bas débit à l'échelle d'un même corps (i.e. coopération intra-WBAN), entre réseaux distincts (i.e. coopération inter-WBAN), et/ou vis-à-vis de l'infrastructure environnante. Ces nouvelles fonctions coopératives présentent un intérêt pour des applications telles que la navigation de groupe ou la capture de mouvement à large échelle. Ce sujet d'étude, par essence multidisciplinaire, a permis d'aborder des questions de recherche variées, humine-biomécanique et de ayant trait à la modélisation physique (e.g. modélisation spatio-temporelle des métriques de radiolocalisation en situation de mobilité, modélisation de la mobilité groupe...), au développement d'algorithmes adaptés aux observables disponibles (e.g. algorithmes de positionnement coopératifs et distribués, sélection et ordonnancement des liens/mesures entre les nœuds...), aux mécanismes d'accès et de mise en réseau (i.e. en support aux mesures coopératives et au positionnement itératif). Les bénéfices et les limites de certaines de ces fonctions ont été en partie éprouvés expérimentalement, au moyen de plateformes radio réelles. Les différents développements réalisés tenaient compte, autant que possible, des contraintes liées aux standards de communication WBAN émergeants (e.g. Impulse Radio - Ultra Wideband (IR-UWB) IEEE 802.15.6), par exemple en termes de bande fréquentielle ou de taux d'erreur.

How are neuromodulatory networks organised to adapt sensory discrimination for different contexts? I hypothesised that neurons within a sensory circuit express different neuromodulatory receptors for differential modulation. Here I aimed to use the simple and genetically amenable Drosophila larval Mushroom Body (MB) calyx, a higher order processing area involved in learned odour discrimination, as a model to map octopamine (OA) neuromodulatory circuitry. I first identified olfactory projection neurons (PNs), a GABAergic feedback neuron and cholinergic extrinsic neurons as putative postsynaptic partners to OA neurons in the MB calyx using GFP reconstitution across synaptic partners. Next, I used novel EGFP-tagged OA receptors generated from recombination-mediated cassette exchange with MiMIC insertions in receptor genes to visualise endogenous expression patterns of OA receptors. Most notably, this is the first report of α2-adrenergic-like OA receptor localisation in any insect. For the first time, I showed that the α1-adrenergic-like OAMB localised to PN presynaptic terminals in the calyx; while Octβ1R localised diffusely in the calyx, resembling the innervation pattern of MB neuron dendrites. I detected EGFP-tagged Octα2R and Octβ2R in some PN cell bodies but not in neuron terminals - suggesting that Octα2R and Octβ2R may be expressed in some PNs, provided the misfolded fusion proteins are retained in the cell bodies of the neurons they are normally expressed in. Furthermore, I found that Octα2R and GABAAR fusion proteins localised to OA cell bodies but not to neuronal terminals, suggesting that OA neurons are subjected to inhibition, again given that these are not artefacts of the fusion proteins. To obtain tools to study OA modulation in the larval calyx, I then confirmed the expression patterns of driver lines that more specifically labelled calyx-innervating OA and extrinsic neurons, and tested the efficacy of three OAMB receptor knockdown lines. This initial attempt of mapping OA receptors, while subjected to further verification and development, is consistent with my hypothesis that a single neuromodulatory source can regulate multiple neuronal types in the same circuit through the distribution of different types of neuromodulatory receptors. This provides a new perspective in how the anatomical organisation of neuromodulation within a sensory network may translate to flexible outputs.

This thesis, divided into two parts, is concerned with the analysis of spectral and dynamical characteristics of certain quantum spin systems in the presence of either I) quenched disorder, or II) dynamical noise. In the first part, the quantum random energy model (QREM), a mean-field spin glass model with a many-body localisation transition, is studied. In Chapter 2, we attempt a diagrammatic perturbative analysis of the QREM from the ergodic side, proceeding by analogy to the single-particle theory of weak localisation. Whilst we are able to describe diffusion, the analogy breaks down and a description of the onset of localisation in terms of quantum corrections quickly becomes intractable. Some progress is possible by deriving a quantum kinetic equation, namely the relaxation of the one-spin reduced density matrix is determined, but this affords little insight and extension to two-spin quantities is difficult. We change our approach in Chapter 3, studying instead a stroboscopic version of the model using the formalism of quantum graphs. Here, an analytic evaluation of the form factor in the diagonal approximation is possible, which we find to be consistent with the universal random matrix theory (RMT) result in the ergodic regime. In Chapter 4, we replace the QREM's transverse field with a random kinetic term and present a diagrammatic calculation of the average density of states, exact in the large-N limit, and interpret the result in terms of the addition of freely independent random variables. In the second part, we turn our attention to noisy quantum spins. Chapter 5 is concerned with noninteracting spins coupled to a common stochastic field; correlations arising from the common noise relax only due to the spins' differing precession frequencies. Our key result is a mapping of the equation of motion of n-spin correlators onto the (integrable) non-Hermitian Richardson-Gaudin model, enabling exact calculation of the relaxation rate of correlations. The second problem, addressed in Chapter 6, is that of the dynamics of operator moments in a noisy Heisenberg model; qualitatively different behaviour is found depending on whether or not the noise conserves a component of spin. In the case of nonconserving noise, we report that the evolution of the second moment maps onto the Fredrickson-Andersen model - a kinetically constrained model originally introduced to describe the glass transition. This facilitates a rigorous study of operator spreading in a continuous-time model, providing a complementary viewpoint to recent investigations of random unitary circuits.

Domestic robots developed to support human beings by performing daily tasks such as cleaning should also be able to help in emergencies by finding, analysing, and assisting persons in need of first aid. Here such a robot capable of performing some useful task related to first aid is referred to as a First Aid Mobile Robot (FAMR). One challenge which to the author's knowledge has not been solved is how such a FAMR can find a fallen person's pose within an environment, recognising locations of points of interest for first aid such as the mouth, nose, chin, chest and hands on a map. To overcome the challenge, a new approach is introduced based on leveraging a robot's capabilities (multiple sensors and mobility), called AHBL. AHBL comprises four steps: Anomaly detection, Human detection, Body part recognition, and Localisation on a map. It was broken down into four steps for modularity (e.g., a different way of detecting anomalies can be slipped in without changing the other modules) and because it was not clear which step is hardest to implement. As a result of evaluating AHBL, a FAMR developed for this work was able to find the pose of a fallen person (a mannequin) in a known environment with an average success rate of 83%, and an average localisation discrepancy of 1.47cm between estimated body part locations and ground truth. The presented approach can be adapted for use in other robots and contexts, and can act as a starting point toward designing systems for autonomous robotic first aid.

Le cerveau construit la sensation d'être dans son corps grâce aux entrées sensorielles. Des atteintes neurologiques et des manipulations expérimentales modifient la localisation du soi, dévoilant ses bases multisensorielles. Les signaux vestibulaires, proprioceptifs et intéroceptifs sont maintenant reconnus comme aussi importants pour le soi que les signaux visuels ou tactiles. Cette thèse approfondit l'étude des bases vestibulaires et multisensorielles de la localisation du soi, qui restent encore à élucider. Une première étude concerne l'influence des signaux sensorimoteurs liés à la locomotion sur la localisation du soi. Notre adaptation de l'illusion du corps entier en réalité virtuelle montre que les signaux de mouvement ancrent le soi au corps. Une tâche de locomotion impliquait un plus fort ancrage du soi au corps qu'une tâche d'imagerie mentale chez les mêmes participants immobiles. Une deuxième étude chez des patients avec une perte vestibulaire bilatérale ancienne ne révéla pas de changement d'intéroception cardiaque ni d’ancrage du soi au corps, malgré une atténuation des sensations corporelles liées aux émotions chez les patients. La représentation du soi ne serait donc pas maintenue par une compensation intéroceptive après une perte vestibulaire. Une troisième étude combinant électrophysiologie vestibulaire et neurosciences sociales montre que l'observation de soi ou d'autrui inhibe le traitement des informations vestibulaires. Le soi corporel dépendrait donc de l'intégration de signaux multisensoriels eux-mêmes influencés par les contraintes cognitives des représentations du soi et d'autrui
The brain creates the feeling of being located in the body thanks to sensory inputs. Neurological disorders and experimental manipulations can alter self-location. Although self-location is difficult to study, its multisensory underpinnings are progressively being revealed. It is now acknowledged that vestibular, proprioceptive et interoceptive information are as important to body self-awareness as visual or tactile information. This PhD thesis aims to advance the study of the vestibular et multisensory bases of self-location, the underlying multisensory mechanisms still needing to be elucidated. A first study measured the influence of sensorimotor signals generated by locomotion on self-location. By adapting the full-body illusion paradigm to virtual reality, we showed that a locomotion task involved a stronger anchoring of the self to the body than a mental imaging task in immobile participants. A second study in patients with a bilateral vestibular loss did not reveal any change in cardiac interoception nor self-body closeness, although patients showed decrease in emotion-related body sensations. Consistent body representations after long-term vestibular loss would therefore not depend on cardiac interoceptive compensation. A third study merged vestibular electrophysiology with social neuroscience to show that observing the self et others inhibits vestibular information processing. The bodily self would therefore depend on the integration of multisensory signals that are themselves influenced by the cognitive constraints of representations of the self and others

La production endogène ou la prise exogène d’hormones sexuelles chez la femme génère un climat hormonal qui lui est propre. Ces particularités endocriniennes influent sur la composition corporelle et modifient les sécrétions et/ou la sensibilité de certaines hormones clés du métabolisme énergétique pouvant conduire à une utilisation spécifique des substrats énergétiques à l’exercice. L’objectif de ce travail était d’étudier l’influence d’une contraception orale (CO : mini dosée monophasique), de la prise alimentaire pré-exercice et de la localisation des graisses sur les réponses métaboliques et hormonales de la femme préménopausée et normo-pondérée à l’exercice (45 min à 65% de O2max). Nos résultats ont montré que la prise d’une CO ne modifiait pas les réponses métaboliques et hormonales et l’utilisation des substrats énergétiques à l’exercice quel que soit le statut nutritionnel des sujets (exercice à jeun ou en situation postprandiale). Cependant, à l’exercice, une situation de jeûne a favorisé une augmentation de l’oxydation lipidique et cela quel que soit le statut hormonal des sujets (CO+ ou CO-). En situation postprandiale, l’exercice physique a stimulé l’activité lipolytique chez des femmes CO+ et CO- sans distinction entre les deux groupes. Enfin, quand l’utilisation des substrats énergétiques à l’exercice est appréhendée en fonction du rapport de la masse grasse abdominale/masse grasse des membres inférieurs (A/MI), nos travaux ont montré une augmentation de la mobilisation et de l’oxydation des lipides chez les femmes présentant un plus faible rapport A/MI (malgré des masses corporelles et des tours de taille normaux). Ainsi, au sein d’une population féminine normo-pondérée, les CO minidosées monophasiques ne semblent pas influer sur l’utilisation des substrats énergétiques à l’exercice, alors que la prise alimentaire pré-exercice et la localisation des graisses semblent avoir un impact plus important sur le métabolisme énergétique à l’exercice
In the female population, sexual hormones (endogen production or exogenous consumption) induce particular hormonal status leading to specific body composition and metabolic and hormonal responses at rest and during exercise. The aim of this work was to determine the influence of oral contraception (low dose monophasic combined OC), pre-exercise food intake and body fat mass localization on metabolic and hormonal responses during exercise (45 min at 65% of O2max) in normal weight premenopausal women. Our results showed that OC did not alter substrate mobilization and oxidation during exercise (in fast and postprandial conditions). However, during exercise performed in fast condition, women exhibited greater lipid oxidation rates whatever their hormonal status (OC+ vs OC-). In postprandial condition, exercise increased lipolytic activity in OC+ and OC- women without differences between both groups. Finally, it has been observed that abdominal to lower body (A/LB) fat mass ratio influenced substrate mobilization and oxidation in premenopausal women with normal weights and waist circumferences. Subjects with a lower ratio exhibited greater lipid mobilization and oxidation than those with a higher ratio. Therefore, in normal weight women, low dose monophasic combined OC do not appear to influence substrate oxidation whereas pre-exercise food intake and body fat mass localization may have an important impact on substrate metabolism during exercise

Many problems in applied mathematics and physics are formulated most naturally in terms of matrices, and can be solved by computing functions of these matrices. For example, in quantum mechanics, the coherent dynamics of physical systems is described by the matrix exponential of their Hamiltonian. In state of the art experiments, one can now observe such unitary evolution of many-body systems, which is of fundamental interest in the study of many-body quantum phenomena. On the other hand the theoretical simulation of such non-equilibrium many-body dynamics is very challenging. In this thesis, we develop a symbolic approach to matrix functions and quantum dynamics based on a novel algebraic structure we identify for sets of walks on graphs. We begin by establishing the graph theoretic equivalent to the fundamental theorem of arithmetic: all the walks on any finite digraph uniquely factorise into products of prime elements. These are the simple paths and simple cycles, walks forbidden from visiting any vertex more than once. We give an algorithm that efficiently factorises individual walks and obtain a recursive formula to factorise sets of walks. This yields a universal continued fraction representation for the formal series of all walks on digraphs. It only involves simple paths and simple cycles and is thus called a path-sum. In the second part, we recast matrix functions into path-sums. We present explicit results for a matrix raised to a complex power, the matrix exponential, matrix inverse, and matrix logarithm. We introduce generalised matrix powers which extend desirable properties of the Drazin inverse to all powers of a matrix. In the third part, we derive an intermediary form of path-sum, called walk-sum, relying solely on physical considerations. Walk-sum describes the dynamics of a quantum system as resulting from the coherent superposition of its histories, a discrete analogue to the Feynman path-integrals. Using walk-sum we simulate the dynamics of quantum random walks and of Rydberg-excited Mott insulators. Using path-sum, we demonstrate many-body Anderson localisation in an interacting disordered spin system. We give two observable signatures of this phenomenon: localisation of the system magnetisation and of the linear magnetic response function. Lastly we return to the study of sets of walks. We show that one can construct as many representations of series of walks as there are ways to define a walk product such that the factorisation of a walk always exist and is unique. Illustrating this result we briefly present three further methods to evaluate functions of matrices. Regardless of the method used, we show that graphs are uniquely characterised, up to an isomorphism, by the prime walks they sustain.

Ce mémoire présente une étude théorique des propriétés de localisation collective dans les superfluides de Bose désordonnés ou quasipériodiques. S'il est connu depuis Anderson que le désordre peut localiser les particules libres, comprendre ses effets dans les systèmes quantiques en interaction, où il est à l'origine de transitions de phase et d'effets de localisation non-Triviaux, représente aujourd'hui un défi majeur. En nous focalisant sur le cas d'un gaz de Bose dans le régime de faibles interactions, bien décrit par la théorie de Bogoliubov, nous étudions les transitions de localisation de ses excitations collectives dans différents contextes. Dans le cas d'un vrai désordre dans l'espace continu tout d'abord, nous développons un formalisme de désordre fort allant au-Delà des études antérieures, aboutissant à une description complète des propriétés de localisation des excitations en dimension arbitraire. Nous présentons un diagramme de localisation générique, et une interprétation microscopique de la propagation des excitations dans le désordre. Dans un second temps, nous considérons le cas d'un potentiel quasipériodique unidimensionel, aux propriétés intermédiaires entre un vrai désordre et un potentiel périodique. Notre traitement analytique et numérique du problème révèle une transition de localisation collective, que nous caractérisons et interprétons en termes de localisation dans un potentiel effectif multiharmonique. Pour finir, nous considérons le cas d'un gaz de Bose à deux composants. Nous développons le formalisme général pour étudier ces questions et décrivons la physique de base de ces systèmes qui présentent leurs propres spécificités
In this thesis, we theoretically investigate the collective localization properties of weakly-Interacting Bose superfluids subjected to disordered or quasiperiodic potentials. While disorder has been recognized since Anderson to induce single-Particle localization, the interplay between disorder and interactions in quantum systems is today among the most challenging questions in the field, and underlies fascinating phase transitions and non-Trivial localization effetcs. Focusing on Bose gases in the weakly-Interacting regime for which the Bogoliubov theory proves a successful tool, we study the localization transitions of collective excitations in several contexts. First, in the case of a continuous true disorder, we develop a strong-Disorder formalism going beyond previous studies, providing us with a complete description of the localization behaviour of collective excitations in arbitrary dimension. A generic localization diagram is obtained and the transport of excitations in the disorder is microscopically interpreted. Secondly, we consider the case of one-Dimensional quasiperiodic potentials, which are known to display intermediate properties between periodic and disordered ones. We perform a numerical and analytical treatment of the localization problem of collective excitations, allowing us to quantitatively characterize and interpret the localization transition in terms of an effective multiharmonic problem. Finally, we set up the general inhomogeneous formalism to address such issues in multicomponent Bose gases, and enlighten the basic physic of such systems, which are known to exhibit their own specific features

This diploma thesis deals with the problem of mobile robot localisation in the environment based on current 2D and 3D sensor data and previous records. Work is focused on detecting previously visited places by robot. The implemented system is suitable for loop detection, using the Gestalt 3D descriptors. The output of the system provides corresponding positions on which the robot was already located. The functionality of the system has been tested and evaluated on LiDAR data.

Les réseaux corporels (WBAN) se réfère aux réseaux de capteurs (WSN) "portables" utilisés pour collecter des données personnelles, telles que la fréquence cardiaque ou l'activité humaine. Cette thèse a pour objectif de proposer des algorithmes coopératifs (PHY/MAC) pour effectuer des applications de localisation, tels que la capture de mouvement et la navigation de groupe. Pour cela, nous exploitons les avantages du WBAN avec différentes topologies et différents types de liens: on-body à l'échelle du corps, body-to-body entre les utilisateurs et off-body par rapport à l'infrastructure. La transmission repose sur une radio impulsionnelle (IR-UWB), afin d'obtenir des mesures de distance précises, basées sur l’estimation du temps d'arrivée (TOA). Ainsi, on s’intéresse au problème du positionnement à travers de la conception de stratégies coopératives et en considérant la mobilité du corps et les variations canal. Notre première contribution consiste en la création d'une base de données obtenue avec de scénarios réalistes pour la modélisation de la mobilité et du canal. Ensuite, nous introduisons un simulateur capable d'exploiter nos mesures pour la conception de protocoles. Grâce à ces outils, nous étudions d’abord l'impact de la mobilité et des variations de canal sur l'estimation de la distance avec le protocole "three way-ranging" (3-WR). Ainsi, nous quantifions et comparons l'erreur avec des modèles statistiques. Dans un second temps, nous analysons différentes algorithmes de gestion de ressources pour réduire l'impact de la mobilité sur l'estimation de position. Ensuite, nous proposons une optimisation avec un filtre de Kalman étendu (EKF) pour réduire l'erreur. Enfin, nous proposons un algorithme coopératif basé sur l'analyse d’estimateurs de qualité de lien (LQEs) pour améliorer la fiabilité. Pour cela, nous évaluons le taux de succès de positionnement en utilisant trois modèles de canaux (empirique, simulé et expérimental) avec un algorithme (basé sur la théorie des jeux) pour le choix des ancres virtuelles
Wireless Body Area Networks (WBAN) refers to the family of “wearable” wireless sensor networks (WSN) used to collect personal data, such as human activity, heart rate, sleep sequences or geographical position. This thesis aims at proposing cooperative algorithms and cross-layer mechanisms with WBAN to perform large-scale individual motion capture and coordinated group navigation applications. For this purpose, we exploit the advantages of jointly cooperative and heterogeneous WBAN under full/half-mesh topologies for localization purposes, from on-body links at the body scale, body-to-body links between mobile users of a group and off-body links with respect to the environment and the infrastructure. The wireless transmission relies on an impulse radio Ultra-Wideband (IR-UWB) radio (based on the IEEE 802.15.6 standard), in order to obtain accurate peer-to-peer ranging measurements based on Time of Arrival (ToA) estimates. Thus, we address the problem of positioning and ranging estimation through the design of cross-layer strategies by considering realistic body mobility and channel variations. Our first contribution consists in the creation of an unprecedented WBAN measurement database obtained with real experimental scenarios for mobility and channel modelling. Then, we introduce a discrete-event (WSNet) and deterministic (PyLayers) co-simulator tool able to exploit our measurement database to help us on the design and validation of cooperative algorithms. Using these tools, we investigate the impact of nodes mobility and channel variations on the ranging estimation. In particular, we study the “three-way ranging” (3-WR) protocol and we observed that the delays of 3-WR packets have an impact on the distances estimated in function of the speed of nodes. Then, we quantify and compare the error with statistical models and we show that the error generated by the channel is bigger than the mobility error. In a second time, we extend our study for the position estimation. Thus, we analyze different strategies at MAC layer through scheduling and slot allocation algorithms to reduce the impact of mobility. Then, we propose to optimize our positioning algorithm with an extended Kalman filter (EKF), by using our scheduling strategies and the statistical models of mobility and channel errors. Finally, we propose a distributed-cooperative algorithm based on the analysis of long-term and short-term link quality estimators (LQEs) to improve the reliability of positioning. To do so, we evaluate the positioning success rate under three different channel models (empirical, simulated and experimental) along with a conditional algorithm (based on game theory) for virtual anchor choice. We show that our algorithm improve the number of positions estimated for the nodes with the worst localization performance

This paper addresses the problem of mobile robot localization based on current 2D and 3D data and previous records. Focusing on practical loop detection in the trajectory of a robot. The objective of this work was to evaluate current methods of image processing and depth data for issues of localization in environment. This work uses Bag of Words for 2D data and environment of point cloud with Viewpoint Feature Histogram for 3D data. Designed system was implemented and evaluated.

The recent advances in trapping, cooling, and manipulation of alkali atoms have opened the possibility to create and study novel states of matter. The quantum nature of matter becomes relevant at ultracold temperatures and emergent phenomena, such as Bose-Einstein condensation (BEC), are strongly affected by the interaction between atoms and their statistics. In this thesis we will address some of the physics in ultracold quantum gases, with Bose (Chapter 2 and Chapter 3) and Fermi statistics (Chapter 4), as well as ultracold Bose-Fermi mixtures (Chapter 3). We will discuss phenomena driven by nonlinear interactions, such as, localisation, macroscopic quantum self-trapping, intrinsic decoherence, Mott insulating symmetry states, formation of bro-ken symmetry states and the BCS-BEC crossover. In this thesis new major results can be summarised as follows: {u2022} The establishment of the relation between stationary states and decoherence origi-nated from many-body interactions in double well bosonic systems, Chapter 2. {u2022} The suppression or enhancement of localisation related phenomena (Superfluid and Mott-Insulator states or Macroscopic Quantum Self-trapping) in Bose-Fermi mixtures due to the presence of fermions and the interplay with many-body interactions in few site systems, Chapter 3. {u2022} The mapping of the BCS-BEC crossover problem to a magnetic impurity problem in the BCSside of a Feshbach resonance, and the possible origin of the pseudo gap in strongly interacting ultracold fermion systems, Chapter 4.