L’environnement maritime du littoral implique de nombreux processus complexes, mais le manque de données en haute résolution couvrant une large zone sur une longue période est souvent l’obstacle principal à des recherches plus approfondies. Le radar haute-fréquence (HF) est un moyen de faire de la télédétection afin d’obtenir pratiquement en temps réel de l’information sur la surface de la mer et sur une large zone. Ainsi l’étude de l’inversion des paramètres marins à partir de données issues de radars HF est réellement porteuse de sens. Cette thèse fait l’usage d’un jeu de données collectées durant 13 mois par deux réseaux de radar HF à commande de phase pour étudier les caractéristiques de signaux d’échos de la mer, étudier les données à traiter et les méthodes d’inversion, calculer les paramètres de la surface de la mer et évaluer la précision de l’inversion radar des paramètres de la houle.Cette thèse se réfère à l’onde de sol radar HF, dont les ondes radio interagissent avec l’océan du fait de la diffraction de résonance de Bragg. Nous passons en revue l’historique et les applications du radar HF. Nous rappelons les bases de la théorie des ondes électromagnétiques. Nous décrivons les principes d’inversion des courants de surface de la mer, direction du vent et paramètres de houles. La faisabilité de l’inversion de paramètres de houle est examinée. A partir de l’analyse théorique et des études statistiques de nombreux échantillons de données, cette thèse propose une série de méthodes sur le traitement du signal brut et le contrôle de qualité, ce qui inclut la détermination du niveau de bruit, le moyennage des données dans l’espace et le temps, l’identification correcte des pics spectraux, le seuil de largeur de pic, etc. Respectant les caractéristiques de différents processus physiques, les inversions de courant et de vent utilisent des spectres collectés toutes les 20 minutes ; l’inversion des paramètres de houle utilise des spectres moyennés sur 1 heure. Les statistiques des spectres utilisés pour le calcul des paramètres de houle sont présentées pour chacune des stations. Un ensemble de programme efficaces de calculs automatiques avec une complexité algorithme réduite sont développés pour réaliser le traitement et en tirer les paramètres marins.Les vitesses de courants radiales sont obtenues à partir d’une unique station radar. Les champs de vecteurs de courants sont obtenus en combinant chaque station. On montre une année de débit moyen dans la mer d’Iroise, ainsi que le calcul de la vorticité et de la divergence. On étudie un ensemble de données d’un mois du radar SeaSonde de Qingdao. Les schémas de débit moyen, ainsi que la vorticité et la divergence sur un mois sont présentés.La direction relative du vent par rapport à la direction de visée du radar est mesurée à travers le ratio des amplitudes des pics de Bragg. Différents modèles empiriques sont employés pour obtenir la vitesse relative du vent par inversion radar. Les résultats présentés sont en accord avec les estimations prédites par le modèle. Différents modèles de distribution directionnelle sont utilisés pour mesurer le facteur de diffusion pour la mer d’Iroise.Cette thèse se concentre sur l’étude des paramètres de houle. Les résultats sont validés à l’aide de bouées et de données du modèle de vagues (Wavewatch III). L’estimation montre que la précision de la fréquence de houle est très bonne, la précision sur la hauteur significative de houle est très raisonnable et la précision sur la direction absolue de la houle est faible. La cohérence des mesures par chacune des stations radars est vérifiée par comparaison entre les deux. L’utilisation conjointe des échantillons est également prise en charge pour réaliser l’inversion. L’utilisation de deux radars n’améliore pas seulement la précision, mais résout aussi l’ambiguïté de direction relative de houle à partir d’une unique station et donne la direction absolue de vague avec une certaine précision. / Nearshore marine environment contains many complex processes, but the lack of high-resolution data over a large area during a long time is often the primary obstacle to further research. High-frequency (HF) radar is a mean of remote sensing which obtains continuous near-real time sea surface information over a large area. Thus the study of inversion of marine parameters from HF radar data is very meaningful. Thisthesis makes use of a 13-month-long dataset collected by two phased array HF radar to investigate the characteristics of the sea echo signals, study the data processing and inversion methods, compute sea surface parameters and evaluate the accuracy of radarinversion of swell parameters.The thesis refers to the ground wave HF radar, whose radio waves interact with ocean by Bragg resonance scattering. The development history and applications of HF radar is introduced. The basic theory of electromagnetic wave is reviewed. The principles of inversion of sea surface current, wind direction and swell parameters are described. The feasibility of the swell parameter inversion is investigated. Based on theoretical analysis and statistical studies of a large number of samples, the thesis proposes a series of methods on raw signal processing and quality control, including the determination of the noise level, data averaging in space and time, the proper identification of spectral peaks, the peak width threshold, etc. Respecting the characteristics of different physical processes, inversions of current and wind use spectra collected every 20 min; inversion of swell parameters uses one-hour averaged spectra. The statistics of qualified spectra for swell parameter calculations are presented for both stations. A set of efficient, with a reduced computational cost, automatic computing programs are developed to do the processing and derive marine parameters. Radial current velocities are derived from single radar station. Current vector fields are obtained by combination of both stations. One-year mean flow field in the Iroise Sea is shown, together with the computation of vorticity and divergence. A one-month SeaSonde radar dataset off Qingdao is studied. One-month mean flow pattern together with vorticity and divergence are presented.Relative wind direction with respect to radar look direction is measured through ratio of Bragg peaks amplitudes. Different empirical models are employed to derive radar-inverted relative wind direction. Results show reasonable agreement with model estimations. Different directional distribution models are used to measure the spreading factor for the Iroise Sea. The thesis focuses on the study of swell parameters. Results are validated by buoy and wave model (WAVEWATCH III) data. The assessments show that the accuracy of swell frequency is very good, the accuracy of swell significant waveheight is reasonable, and the accuracy of relative swell direction is low.Consistency of measurements by both radar stations is verified by comparison between the two. This also supports the use of double samples to do the inversion. Use of two radars not only further improves the accuracy but also solves the ambiguity of relative swell direction from single station and gives the absolute wave direction to a certain precision. The thesis proposes a constant relative directionmethod to derive swell significant waveheight, based on the studies of radar integral equation and the inverted results of relative swell direction. This proposal is demonstrated to improve the agreement of radar inversion and buoy/model provided significant waveheight and increases significantly the number of samples. The thesis investigates the accuracy of swell parameters obtained by HF radar. Contributions of random errors in radar observations are quantified. Comparing the differences between radar and buoy/model estimations gives assessments of the contribution of radar intrinsic uncertainty and contribution of other factors.

Different studies have shown that faces seen with a direct gaze (creating eye contact) are more likely to be recognized than faces seen with a laterally deviated gaze. The present work was aimed at determining underlying processes of this gaze direction effect. More precisely, whether this effect was due to a more elaborated encoding of faces with direct gaze because of the social importance of the eye contact was tested. Results obtained showed that the gaze direction effect is a highly sensitive effect which influence on memory for faces is probably more incidental than previously hypothesized./ Différentes études ont montré que les visages vus avec un regard direct (créant un contact visuel) ont plus de chance dêtre reconnus que les visages vus avec un regard dévié latéralement. Ce travail avait pour but de déterminer la nature des processus sous-jacents à cet effet de la direction du regard. Plus précisément, nous avons testé lhypothèse dun encodage plus élaboré des visages avec un regard direct dû à la signification sociale du contact visuel. Les résultats obtenus ont montré que leffet de la direction du regard est un effet très sensible dont linfluence sur la mémoire pourrait être plus incidente que ce qui avait été proposé dans la littérature.

Titanium based alloys reinforced uniaxially with silicon carbide fibres (Ti/SiC) are advanced and innovative materials for aerospace vehicles. To avoid potential problems, these new materials should be extensively tested and analyzed before application. This research focuses on experimental fracture toughness study on 0.5 mm thick Ti/SiC composite materials for aerospace applications. The fracture toughness tests are mainly based on BS 7448 with some modifications for transversely isotropic behaviour of the composite materials. By loading on specimens in the direction perpendicular to the fibre axis, three critical values of fracture toughness parameters characterizing fracture resistance of material, plane strain fracture toughness [Plane strain fracture toughness }, critical crack tip opening displacement [Critical crack tip opening displacement ] and critical J-integral [Critical at the onset of brittle crack extension or pop-in when Δa is less than 0.2 mm. ]are measured for two kinds of titanium alloy specimens and three kinds of Ti/SiC composites specimens. The values of [Provisional value of Plane strain fracture toughness ] obtained from the fracture toughness tests are not valid [Plane strain fracture toughness ] for these materials, since the thickness of specimens is insufficient to satisfy the minimum thickness criterion; however, the results could be used as particular critical fracture toughness parameter for 0.5 mm thick structures of the materials. The valid values of [Critical J at the onset of brittle crack extension or pop-in when Δa is less than 0.2 mm. ] and [Critical crack tip opening displacement ] could be used as fracture toughness parameters for all thickness of structures of the materials. The results also show that: fracture toughness of the titanium alloys decreases dramatically after being unidirectional reinforced with SiC fibre, which is mainly triggered by poor fibre/matrix bonding condition. Moreover, Ti-Al3-V2.5 reinforced with 25% volume fraction SiC fibre performs better than the other two composites in fracture resistance.

The aim of this paper is to study whether the way directioners (One Direction fans) on Twitter express self-understandings denote fandom as a sacred experience. For this purpose, the data was analyzed in relation to Nicholas Jay Demerath III typology of the varieties of the sacred experience. The method used was discursive psychology. The data was analyzed by how the fans draw the line between “us” and “them”, when expressing their self-understandings and their position in relation to others.   Five themes were identified: (1) positioning and demarcation for membership, (2) group identity, (3) conflict, (4) the norms for behavior, opinions and language and (5) the group’s role and function. The directioners were using three interpretative repertoires; the One Direction fandom as identity, lifestyle and therapy.   The conclusion when analyzing the data in relation to Demeraths typology was that directioners expressed notions of the One Direction fandom as a sacred experience in an integrative manner, that is, being a “directioner” was described as marginal and confirmatory.  This suggests that the One Direction fandom consists of people that are outside the mainstream who are brought in to a social unit by joining the fandom. The data also contradicts this; the high demands for directioners to be active on Twitter can create an unsafe community.   Being in the One Direction fandom can be a possible source for a sacred experience as experienced consequences since it has given the fans identity, improved their lives and helped them escape reality. The experience of the sacred varies depending on the devotion of the fans.

We derive a technique for scaling the search directions of feasible direction methods when applied to optimization problems over Cartesian product sets. It is proved that when the scaling is included in a convergent feasible direction method, also the new method will be convergent. The scaling technique is applied to the Frank-Wolfe method, the partanized Frank-Wolfe method and a heuristic Frank-Wolfe method. The performance of  these algorithms with and without scaling is evaluated on the stochastic transportation problem. It is found that the scaling technique has the ability to improve the performance of some methods. In particular we observed a huge improvement in the performance of the partanized Frank-Wolfe method, especially when the scaling is used together with an exact line search and when the number of sets in the Cartesian product is large.

L’orientation spatiale et la fonction de navigation sont des processus contrôlés par des circuits et éléments neuronaux bien précis. Le présubiculum, aire cortical de transition de la région parahippocampique, est situé entre l’hippocampe et le cortex entorhinal. Le présubiculum est impliqué dans la navigation spatiale à la fois chez l’animal et l’Homme. Plus de la moitié des neurones du présubiculum sont des cellules de direction de la tête qui déchargent en fonction de la direction prise par la tête de l’animal. Le présubiculum est un carrefour majeur pour le transfert d’information de direction de la tête et de l’information visuelle aux régions de la formation hippocampique et parahippocampique et sous-corticale. Malgré son importance fonctionnelle, le traitement de l’information au sein du circuit présubiculaire à 6 couches reste encore peu connu. Au cours de ma thèse, j’ai étudié les éléments inhibiteurs qui composent le microcircuit présubiculaire à partir de tranches aigües de cerveau de souris en utilisant la technique du patch-clamp. J’ai caractérisé les propriétés anatomique et électriques des interneurones ainsi que leur connectivité locale et à distances avec d’autres régions corticales.Dans un premier temps, j’ai étudié la diversité des interneurones exprimant la parvalbumine et la somatostatine à partir de lignées de souris transgéniques exprimant une protéine fluorescente dans les interneurones. J’ai montré l’existence des cellules en panier à décharge rapide exprimant la parvalbumine et des cellules de Martinotti à bas seuil d’activation exprimant la somatostatine. J’ai également décrit un troisième groupe atypique avec des propriétés électriques intermédiaires et des morphologies hétérogènes. L’existence de ce groupe transitionnel pourrait s’expliquer par la présence d’interneurones exprimant à la fois la parvalbumine et la somatostatine. Ainsi, le microcircuit inhibiteur du présubiculum semble partager toute la complexité des autres aires corticales. Dans un second temps, je me suis intéressée à l’intégration des entrées thalamiques par les neurones excitateurs et inhibiteurs dans les couches superficielles du présubiculum à l’aide de la technique du double patch-clamp. J’ai montré que les axones thalamiques innervent sélectivement les couches superficielles et plus particulièrement, contactent directement les cellules de projection vers le cortex entorhinal ainsi que les interneurons exprimant la parvalbumine dans la couche 3 du présubiculum. En revanche, les interneurons exprimant la somatostatine sont indirectement recrutés par les cellules pyramidales du microcircuit. Ces interneurones joueraient un double rôle à la fois dans l’inhibition latérale et le maintien d’une décharge soutenue des cellules principales. Du fait de la forte probabilité de connexion entre les cellules principales et les interneurones exprimant la parvalbumine, ces derniers seraient impliqués dans l’inhibition de type feed-forward. Mon travail de thèse a permis d’apporter des connaissances fondamentales concernant l’inhibition au sein du présubiculum. Il a permis de dévoiler une diversité d’interneurones GABAergiques et de montrer l’existence de circuits neuronaux canoniques de type « feedforward » et « feedback » qui seraient recrutés à différents moments de la signalisation de la direction de la tête. / Spatial orientation and navigation are controlled by specific neuronal circuits and elements. The presubiculum, a transitional cortical area of the parahippocampal formation, is located between the hippocampus and the entorhinal cortex, and it participates in spatial navigation in animals and humans. More than half of presubicular neurons are head direction cells that fire as a function of the directional heading. The presubiculum is thought to be a crucial node for transferring directional heading information to the entorhinal-hippocampal network, and feeding back visual landmark information to upstream regions of the head directional circuit. Despite its functional importance, information processing within the 6-layered presubicular microcircuit remains not completely understood. During my PhD, I studied inhibitory neurons of the presubicular microcircuit in the slice preparation using patch-clamp recordings. I characterized their anatomo-physiological properties as well as their functional connectivity with local principal neurons. In the first part, I examined the diversity of two major populations of GABAergic neurons, the parvalbumin (PV) and somatostatin (SOM) expressing interneurons in mouse presubiculum. Using transgenic mouse strains Pvalb-Cre, Sst-Cre and X98, where interneurons were fluorescently labeled, I showed the existence of typical PV fast-spiking basket-like interneurons mainly in the Pvalb-Cre line and SOM low-threshold spiking Martinotti cell-like interneurons in the X98 and Sst-Cre line. Unsupervised cluster analysis based on electrophysiological parameters further revealed a transitional group containing interneurons from either Pvalb-Cre or Sst-cre lines with quasi-fast-spiking properties and heterogeneous morphologies. A small subpopulation of ~6% of interneurons co-expressed PV and SOM in mouse presubiculum. The presubiculum appears to share the whole complexity of other cortical areas in term of inhibition. In the second part, I investigated the integration of thalamic inputs by principal neurons as well as PV and SST interneurons in the presubiculum using double patch-clamp recordings. I found that thalamic axons selectively innervated superficial layers and made direct synaptic contacts with pyramidal neurons that project to medial entorhinal cortex and also with PV interneurons in superficial layer 3. In contrast, SST interneurons were indirectly recruited by presubicular pyramidal cells in a facilitating and frequency dependent manner. They may mediate lateral inhibition onto nearby principal cells, and at the same time, preserve sustained firing of principal neurons. In paired recording experiments, I found that PV cells inhibit neighboring pyramidal neurons with a high connection probability. PV interneurons are rapidly recruited by thalamic excitation and mediate feed-forward inhibition in presubicular pyramidal neurons. My PhD work brought fundamental knowledge about the presubicular inhibitory microcircuit. It has unraveled different populations of GABAergic interneurons and revealed canonical feedforward and feedback inhibitory motifs that are likely to be recruited at different times during head direction signaling.

Change of direction speed (CODS) is an important determinant of performance in many sports. Greater stiffness of the lower limb should be beneficial to CODS, but this had not been well investigated. The purpose of this thesis was to establish the relationship between vertical stiffness, vertical stiffness asymmetries and CODS, with a view to augmenting CODS performance. The pilot study and studies 1-2 sought to determine the most reliable and ecologically valid method to assess stiffness in athletes required to perform changes of direction. The pilot study reported that the use of ultrasonography to determine Achilles tendon stiffness did not demonstrate appropriate reliability for inclusion in subsequent studies. Coefficients of variation (CVs) in excess of 27% were reported during an isometric plantar flexion task. Study 1 reported that CVs for vertical stiffness were lower when assessed during unilateral drop jumping (~7%) than during bilateral drop jumping (~12%) or bilateral hopping (~14%). Study 2 reported that the expression of vertical stiffness (P = 0.033) and vertical stiffness symmetry angle (P = 0.006) was significantly different across three performance tasks: unilateral drop jumping, bilateral drop jumping and bilateral hopping. Asymmetry percentages between compliant and stiff limbs were 5.6% (P < 0.001; d: 0.22), 23.3% (P = 0.001; d = 0.86) and 12.4% (P = 0.001; d = 0.39), respectively. Given the findings of studies 1 and 2, this thesis demonstrated the reliability and validity of a novel method by which to assess vertical stiffness - the unilateral drop jump. This task was used in subsequent studies to measure vertical stiffness. Study 3 sought to determine if vertical stiffness and vertical stiffness asymmetries influenced CODS performance determined during a 90o cutting task. Multiple regression analyses reported that mean vertical stiffness and asymmetry in jump height explained 63% (r2 = 0.63; P = 0.001) of CODS performance. Study 3 was the first investigation to demonstrate the importance of vertical stiffness to CODS performance. Study 4 sought to determine if acute exercise interventions designed to augment vertical stiffness would improve CODS. Unilateral and bilateral ‘stiffness’ interventions were evaluated against a control condition. CODS performances following the unilateral intervention were significantly faster than control (1.7%; P= 0.011; d = -1.08), but not significantly faster than the bilateral intervention (1.0% faster; P = 0.14; d = -0.59). Versus control, vertical stiffness was 14% greater (P = 0.049; d = 0.39) following the unilateral intervention. Study 4 demonstrated that a novel unilateral ‘stiffness’ intervention improved vertical stiffness and CODS performance. This highlights that the potential applicability of unilateral stiffness interventions in the pre-performance preparation of athletes.

No description available.

This thesis project is about a television engineer in the Department of Radio, Television and Film at the University of North Texas. This project records the engineer's activities in the Department and interviews him about his career path. An accompanying written production report describes the pre-production, production and post-production processes of this project.

Les femtocellules sont déployées par des FAPs dans la couverture des macrocellules afin d'offrir aux utilisateurs un service continu aussi bien à l'intérieur qu'à l'extérieur.Elles sont caractérisées par une courte portée,faible puissance et ne peuvent couvrir qu'un nombre limité des utilisateurs.Ces caractéristiques rendent la gestion de la mobilité l'un des plus importants défis à résoudre.Dans cette thèse,nous proposons des nouveaux algorithmes de handover.En premier lieu,nous considérons la direction du mobile comme un paramètre clé pour la prise de décision de Handover.Nous proposons un algorithme de handover nommé OHMF basé sur l'optimisation de la liste de FAPs candidats tout en considérant la qualité de signal ainsi que la direction de mouvement de mobile.Ensuite,nous proposons un processus de prédiction de direction basé sur la régression linéaire.L'idée est de prédire la position future du mobile tout en tenant compte des positions actuelle et précédente.Cet algorithme est intitulé OHDP. En deuxième lieu,nous nous intéressons au problème de prédiction de mobilité pour être plus rigoureux lors de prise de décision de handover.Pour cela,nous utilisons les chaînes de markov cachées comme prédicteur du prochain FAP et nous proposons un algorithme de handover nommé OHMP. Afin d'adapter notre solution à toutes les contraintes du réseau femtocellules,nous proposons un algorithme de handover intitulé OHMP-CAC qui intègre un CAC approprié au réseau étudié et une différenciation de service avec et sans contraintes de QoS.Des études de performances basées sur des simulations et des traces de mobilité réelles ont été réalisées pour évaluer l'efficacité de nos propositions. / Femtocell network are deployed in the macrocell’s coverage to provide extended services with better performances. Femtocells have a short-range and low power transmissions.Each FAP supports a few number of connected users.Owing to these inherent features, one of the most challenging issues for the femtocellular network deployment remains the mobility management.In this thesis, we propose new handovers algorithms adapted to the characteristics of femtocells network.As a first part,we consider the direction of mobile user as a key parameter for the handover decision.To do so,we propose a new handover algorithm called OHMF. Its main purpose is the optimization of the list of FAPs candidates based on signal quality as well as the mobile direction to better choose the FAP target.After that, we propose an algorithm called OHDP based on the direction prediction using the linear regression.The idea behind this is to predict the future position of mobile based on its current and previous position. As a second part, we focus on mobility prediction problem to make an efficient handover decision.We propose a novel handoff decision algorithm called OHMP that uses HMM as a predictor to accurately estimate the next FAP that a mobile UE would visit,given its current and historical movement information.In order to adapt our solution to the characteristics of femtocells network,we propose a handover algorithm called OHMP-CAC based on HMM tool as a predictor, a proposed CAC and the availability of resources of the predicted FAP,SINR and the traffic type.In order to assess the efficiency of our proposals,all underlying algorithms are evaluated through simulations and real mobility traces.