Détection de structures cohérentes dans des écoulements fluides et interfaces homme-machine pour l'exploration et la visualisation interactive de données scientifiques

Depuis l'identification par Brown \& Roshko, en 1974, de structures jouant un rôle majeur dans le mélange d'un écoulement turbulent, la recherche de structures cohérentes a été un des principaux axes d'étude en mécanique des fluides.Les travaux présentés dans ce manuscrit s'inscrivent dans cette voie.La première partie du manuscrit traite ainsi de l'identification de structures cohérentes. Elle se compose de trois chapitres abordant deux techniques d identification. La Décomposition en mode dynamique (DMD), ainsi que des variantes généralisant son champ applicatif est présenté dans le premier chapitre. Cette méthode propose une représentation par modes spatiaux et temporels d'un ensemble de données. Une méthode pour la sélection de composantes particulièrement représentatives de la dynamique, i.e. présentant de bonnes qualités d'observabilité, se basant sur cette décomposition est également décrite dans ce chapitre.Le deuxième chapitre traite de la détection de structures cohérentes lagrangienne, par suivi de particules. Ces structures permettent d'identifier les frontières matérielles et apportent des éclaircissements sur les mécanismes du mélange au sein de l'écoulement considéré.Ces méthodes sont appliquées, dans le chapitre trois, au cas d un écoulement incompressible affleurant une cavité ouverte.La seconde partie du manuscrit traite des questions de représentation et discrimination de données scientifiques.Une réponse à la question de la représentation de structures cohérentes a été la mise en place d'outils permettant la visualisation interactive de jeux de données scientifiques, qui dont la présentation fait l'objet du chapitre quatre. En particulier, l'utilisation d'objets tangibles, représentant les données dans le monde réel, permet une exploration plus efficace des ensembles de volumétriques de données scientifiques. La question d'une perception et discrimination efficace de données représentées, e.g. la différentiation entre deux valeurs proches, est abordée dans le cinquième chapitre.Brown \& Roshko identify the key role, as soon as 1974, of coherent structures in the mixing of a turbulenet jet. Since, the seek for coherent structures has been a major field in fluid mechanics. This manuscript follows this path, and aims at describing algorithm to compute and explore coherent structures from fluid mechanics dataset.The first part of this manuscript is dedicated to present algorithms for the computations of coherent structures from dataset. The first chapter exposes the Dynamical Modes Decomposition, and presents improvements of the method. A criterion to estimate the observability properties of components of the state vector is also presented.The second chapter aims at describing an efficient algorithm to compute Lagrangian Coherent Structures, which are somewhat equivalent to material frontiers in fluid flows, and highlight mixing dynamics.This methods are applied, in a third chapter, to caracterize the dynamics of an open cavity flow.The second parti of this manuscript is dedicated to the representation and discrimination of scientific dataset.The fourth chapter presents metaphors for the interactive exploration of scientific and volumetric dataset. The use of tangible interfaces is investigated. The last chapter deals with the differenciation between represented data, by proposing an algorithm for the differenciation between close but different signals.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Impact of a telenursing service on satisfaction and health outcomes of children with inflammatory rheumatic diseases and their families: a crossover randomized trial study protocol.

BACKGROUND: Pediatric rheumatic diseases have a significant impact on children's quality of life and family functioning. Disease control and management of the symptoms are important to minimize disability and pain. Specialist clinical nurses play a key role in supporting medical teams, recognizing poor disease control and the need for treatment changes, providing a resource to patients on treatment options and access to additional support and advice, and identifying best practices to achieve optimal outcomes for patients and their families. This highlights the importance of investigating follow-up telenursing (TN) consultations with experienced, specialist clinical nurses in rheumatology to provide this support to children and their families. METHODS/DESIGN: This randomized crossover, experimental longitudinal study will compare the effects of standard care against a novel telenursing consultation on children's and family outcomes. It will examine children below 16 years old, recently diagnosed with inflammatory rheumatic diseases, who attend the pediatric rheumatology outpatient clinic of a tertiary referral hospital in western Switzerland, and one of their parents. The telenursing consultation, at least once a month, by a qualified, experienced, specialist nurse in pediatric rheumatology will consist of providing affective support, health information, and aid to decision-making. Cox's Interaction Model of Client Health Behavior serves as the theoretical framework for this study. The primary outcome measure is satisfaction and this will be assessed using mixed methods (quantitative and qualitative data). Secondary outcome measures include disease activity, quality of life, adherence to treatment, use of the telenursing service, and cost. We plan to enroll 56 children. DISCUSSION: The telenursing consultation is designed to support parents and children/adolescents during the course of the disease with regular follow-up. This project is novel because it is based on a theoretical standardized intervention, yet it allows for individualized care. We expect this trial to confirm the importance of support by a clinical specialist nurse in improving outcomes for children and adolescents with inflammatory rheumatisms. TRIAL REGISTRATION: ClinicalTrial.gov identifier: NCT01511341 (December 1st, 2012)

Impact of a nurse led telephone intervention on satisfaction and health outcomes of children with inflammatory rheumatic diseases and their families: a crossover randomized clinical trial.

Children suffering from rheumatic disease are faced with multidimensional challenges that affect their quality of life and family dynamics. Symptom management and monitoring of the course of the disease over time are important to minimize disability and pain. Poor disease control and anticipation of the need for treatment changes may be prompted by specialist medical follow-up and regular nurse-led consultations with the patient and families, in which information and support is provided. The purpose of this study was to evaluate the impact of a nurse-led telephone intervention or Telenursing (TN) compared to standard care (SC) on satisfaction and health outcomes of children with inflammatory rheumatic diseases and their parents. A multicentered, randomized, longitudinal, crossover trial was conducted with pediatrics outpatients newly diagnosed with inflammatory rheumatic diseases. Participants were randomly assigned to two groups TN and SC for 12 months and crossed-over for the following 12 months. TN consisted of providing individualized affective support, health information and aid to decision making. Satisfaction (primary outcome) and health outcomes were assessed with the Client Satisfaction Questionnaire-8 and the Juvenile Arthritis Multidimensional Assessment Report, respectively. A mixed effect model, including a group x time interaction, was performed for each outcome. Satisfaction was significantly higher when receiving TN (OR = 7.7, 95% CI: 1.8-33.6). Morning stiffness (OR = 3.2, 95% CI: 0.97-7.15) and pain (OR = 2.64, 95% CI: 0.97-7.15) were lower in the TN group. For both outcomes a carry-over effect was observed with a higher impact of TN during the 12 first months of the study. The other outcomes did not show any significant improvements between groups. TN had a positive impact on satisfaction and on morning stiffness and pain of children with inflammatory rheumatic diseases and their families. This highlights the importance of support by specialist nurses in improving satisfaction and symptom management for children with inflammatory rheumatisms and their families. ClinicalTrial.gov identifier: NCT01511341 (December 1st, 2012)

Signature fréquentielle des structures cohérentes-décomposition en modes dynamiques : application à un écoulement en cavité ouverte

La dimension de la dynamique effective d'un écoulement impactant peut-être considérablement réduite par les conditions aux limites et les oscillations auto induites qu'elles engendrent, la signature spectrale étant associée à des structures spatiales remarquables. Une méthode de décomposition (DMD) utilisant l'opérateur de Koopman, permet d'extraire directement les propriétés de la dynamique de l'écoulement non-linéairement saturée. Nous appliquons la DMD pour mettre en évidence la contribution spectrale des structures longitudinales et transversales de l'écoulement de cavité

Fundamental aspects to localize self-catalyzed III-V nanowires on silicon

III-V semiconductor nanowires deterministically placed on top of silicon electronic platform would open many avenues in silicon-based photonics, quantum technologies and energy harvesting. For this to become a reality, gold-free site-selected growth is necessary. Here, we propose a mechanism which gives a clear route for maximizing the nanowire yield in the self-catalyzed growth fashion. It is widely accepted that growth of nanowires occurs on a layerby-layer basis, starting at the triple-phase line. Contrary to common understanding, we find that vertical growth of nanowires starts at the oxide-substrate line interface, forming a ring-like structure several layers thick. This is granted by optimizing the diameter/height aspect ratio and cylindrical symmetry of holes, which impacts the diffusion flux of the group V element through the well-positioned group III droplet. This work provides clear grounds for realistic integration of III-Vs on silicon and for the organized growth of nanowires in other material systems