2,142 research outputs found

    Contrail microphysics in the near wake of a realistic wing through RANS simulations

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    This paper focuses on Steady Reynolds Average Navier Stokes simulations (RANS) of ice particles growth in the near field of a wing-injector configuration. The multiphysics multiphase flow solver CEDRE, enriched with a microphysical model, has been developed in order to simulate the impact of a more real aircraft geometry in contrail formation studies. As a first evaluation case, a simplified aircraft description, i.e. a NACA0012 2D wing with two injectors, has been used. Ice formation has been simulated by assuming water condensation and instantaneous freezing on activated soot particles, initially emitted by aircraft engines. Our investigation focuses on the near field, extending from the nozzle exit until eight wing spans. Although the main goal is to address the question of ice formation, the aerodynamic flow field has been investigated and numerical results compared with existing experimental data. The first results indicate that the exhaust jet is correctly wrapped around the vortex and that the pattern of dilution qualitatively matches observations in the near field. Sensitivity studies to humidity and to the initial soot particle radius have also been performed

    Origin and diversification of dung beetles in Madagascar

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    Madagascar has a rich fauna of dung beetles (Scarabaeinae and Aphodiinae) with almost 300 species described to date. Like most other taxa in Madagascar, dung beetles exhibit an exceptionally high level of endemism (96% of the species). Here,we review the current knowledge of the origin and diversification of Malagasy dung beetles. Based on molecular phylogenies, the extant dung beetles originate from eight colonizations, of which four have given rise to extensive radiations. These radiations have occurred in wet forests, while the few extant species in the less successfu lradiations occur in open and semi-open habitats. We discuss the likely mechanisms of speciation and the ecological characteristics of the extant communities, emphasizing the role of adaptation along environmental gradients and allopatric speciation in generating the exceptionally high beta diversity in Malagasy dung beetles. Phylogeographic analyses of selected species reveal complex patterns with evidence for genetic introgression between old taxa. The introduction of cattle to Madagascar 1500 years ago created a new abundant resource, onto which a few species have shifted and thereby been able to greatly expand their geographical ranges.Peer reviewe

    Social cognition and anxiety following a first-episode of psychosis : markers of clinical remission in schizoprenia and the development of a manualized cognitive-behavioral group intervention for social anxiety

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    Évaluation des prédicteurs de la rémission en schizophrénie en lien avec le développement d'une intervention cognitivo-comportementale de groupe pour le traitement de l'anxiété sociale chez les personnes présentant un premier épisode psychotique. Depuis les dernières années, il existe un intérêt croissant pour la notion de comorbidité en psychiatrie. Malgré cette évolution dans la compréhension des problématiques psychiatriques, la relation entre l'anxiété et la schizophrénie demeure toutefois négligée. Cependant, la problématique de la schizophrénie et d'un trouble comorbide à l'axe I du DSM-IV demeure toujours peu explorée dans les écrits scientifiques disponibles. Parmi la recherche existante, portant plus particulièrement sur la comorbidité d'un trouble relié à l'anxiété chez les personnes qui sont atteints de schizophrénie, un très petit nombre d'études ont exploré les liens qui existent entre les symptômes de l'anxiété et la schizophrénie. Le champ des études portant sur la comorbidité chez les personnes présentant plus particulièrement un premier épisode psychotique, demeure davantage inexploré. L'anxiété sociale est le trouble le plus fréquemment diagnostiqué parmi les troubles qui se retrouvent sur le continuum de l'anxiété. Cette problématique représente aussi l'une des pathologies les plus répandues en ce qui a trait à la comorbidité en schizophrénie. Malgré un intérêt croissant pour l'application de la thérapie cognitivo-comportementale dans le traitement des symptômes reliés à la schizophrénie, très peu d'études ont à ce jour proposé une intervention d'approche cognitivo-comportementale pour l'anxiété sociale spécifiquement adaptée pour les personnes atteintes de schizophrénie. Sur cette base, la présente recherche porte sur une intervention de ce type avec cette population. Nous avons formulé l'hypothèse que les participants qui prendraient part à une thérapie de groupe d'approche cognitivo-comportementale pour l'anxiété sociale qui aurait été adaptée plus particulièrement pour les personnes atteintes de schizophrénie, manifesteraient une réduction significative des symptômes reliés à l'anxiété sociale ainsi que des symptômes psychotiques à la suite de l'intervention. Cette étude portant principalement sur l'efficacité d'un programme d'intervention pour le traitement de l'anxiété sociale en tant que comorbidité en premier épisode de psychose fut développée selon un devis non contrôlé. Dans le cadre de cette étude, 29 participants ont été recrutés et ont donné leur consentement à participer à l'étude. De ce nombre, 26 personnes ont complété avec succès le programme d'intervention. Les participants ont pris part à la thérapie de groupe d'approche cognitivo-comportementale qui s'est déroulée en 14 séances hebdomadaires de 90 minutes chacune. L'effet thérapeutique de l'intervention a été évalué à l'aide de tests « t » d'échantillons appariés (T1 pré-test - T2 post-test) pour toutes les mesures de résultats thérapeutiques qui comprennent l'anxiété sociale, les symptômes positifs et négatifs de la psychose et les symptômes de la psychopathologie générale (dépression, insight, stigma). Le chapitre I de la thèse consiste en une introduction générale qui présente une recension des écrits scientifiques, et plus précisément sur les marqueurs de la rémission clinique en schizophrénie et sur la nature des comorbidités, plus particulièrement l'anxiété sociale chez les personnes présentant un premier épisode psychotique. Les chapitres II et III présentent deux études empiriques indépendantes qui ont examiné l'impact de la cognition sociale pour l'une des études, et, pour l'autre étude, la fonction de la sévérité des symptômes reliés à l'anxiété sur la rémission clinique chez les personnes présentant un premier épisode psychotique. Les résultats de ces recherches ont révélé que les déficits au chapitre de la cognition sociale et la sévérité des symptômes reliés à l'anxiété sont des marqueurs importants de la rémission clinique chez les personnes présentant un premier épisode psychotique. Le chapitre IV comprend un troisième article empirique qui vise à évaluer l'efficacité d'une intervention de groupe d'approche cognitivo-comportementale manualisée pour le traitement des symptômes reliés à l'anxiété sociale chez les personnes présentant un premier épisode psychotique. Les résultats de cette étude révèlent que l'intervention semble contribuer à une réduction significative des symptômes d'anxiété sociale, des symptômes négatifs de la psychose, des symptômes dépressifs et du stigma. Finalement, le chapitre V présente une discussion générale des résultats de la thèse ainsi que des implications cliniques, des considérations méthodologiques et des pistes de recherche future. Les marqueurs de la rémission clinique chez les personnes présentant un premier épisode psychotique sont présentés. Un modèle de l'anxiété sociale en premier épisode psychotique, selon l'intervention de groupe d'approche TCC manualisée, est proposé. Dans l'ensemble, les résultats thérapeutiques de ce programme de recherche suggèrent que l'intervention de groupe d'approche cognitivo-comportementale manualisée doit être soumis à un essai contrôlé randomisé (ECR).\ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : Anxiété sociale, premier épisode psychotique, schizophrénie, thérapie cognitivo-comportementale, intervention psychologique, résultats thérapeutiques, rémission, fonctionnement social, stigma, insigh

    Outsourced Storage and Fulfillment Facility to Enhance the Service Capabilities of Shopping Mall Tenants

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    This paper proposes development of an Inventory and Fulfillment Center (IFC) that will provide a new range of outsourced, centralized storage and services for shopping mall tenants. The paper describes the competitive issues faced by shopping mall tenants, the requirements and features of a centralized, outsourced storage and fulfillment facility, and development of an agent-based model in AnyLogic® to demonstrate the concept. The range of research and business challenges introduced by this new concept are also presented

    Introducing the Concept of Hyperconnected Mobile Production

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    Many globalized businesses are trying to cope with growing competition by strategically expanding their dedicated network of production facilities so as to be able to offer and to deliver time and price competitive offers to their clients across the world. In this paper, exploiting Physical Internet principles, we introduce the concept of hyperconnected mobile production that can alternatively enable businesses to dynamically expand and contract as necessary their production capacity in regions worldwide. First, hyperconnected mobile production exploits open fabs from multiple parties readily available in those regions. Second, these fabs are to rely on plug-and-play production modules. These modules are to be flowed in and out of open fabs worldwide by the fab operators or their business clients so as to absorb dynamic production requirements from customers. Third, the production modules are to be dynamically re-configurable through adding and removing plug-and-play modular resources. We first show that hyperconnected mobile production builds on eight innovation threads: distributed, outsourced, on-demand, modular, additive, mobile, containerized and hyperconnected production. We then provide an overall description of key facets of the hyperconnected mobile production concept and finally elicit a number of promising research avenues

    Aeolian dune development and evolution on a macro-tidal coast with a complex wind regime, Lincolnshire coast, UK

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    Coastal foredunes are natural aeolian bedforms located landward of the backshore and which interact continuously with the beach. Traditionally, coastal dunes have been associated with onshore winds, however they can be found under more complex wind regimes where offshore winds are common such as the UK East coast, Northern Ireland and New Zealand. This research investigates the ways in which foredune-beach interactions occur under a complex wind regime at a range of overlapping temporal and spatial scales and is innovative in that it explicitly links small-scale processes and morphodynamic behaviour to large scale and long-term dynamics. The study area is the north Lincolnshire coast, East England. Detailed observations of airflow at three locations under varying wind regimes revealed considerable spatial variations in wind velocity and direction, however it was possible to determine a general model of how foredune topography deflected and modified airflow and the resultant geomorphological implications (i.e. erosion and deposition). During direct offshore and onshore winds, airflow remained attached and undeflected; and distinct zones of flow deceleration and acceleration could be identified. During oblique winds airflow was deflected to become more parallel to the dune crest. The field sites used are characterized by a seasonal erosion/accretion cycle and a series of increasingly complex models was developed and tested to determine whether it was possible to predict sand volume changes in the foredune-beach system based on a limited number of variables. The model predictions were tested against detailed digital terrain models at a seasonal timescale. The model prediction that best matched the observed (surveyed) sand volume changes included wind speed, direction, grain size, fetch effect controlled by beach inundation and angle of wind approach was accurate to within ±10% for 18 out of 48 tests at the seasonal scale and 6 out of 12 tests over periods of >5 years. A key variable influencing foredune-beach sand volume is the magnitude and frequency of storm surge events and this was not factored in to the model, but may explain the model-observation mismatch over the medium-term on two occasions. Over the past 120 years historical maps and aerial photographs indicate long-term foredune accretion of approximately 2 m year-1 at the three study sites (1891-2010). At this timescale, rates of coastal foredune accretion reflect the low occurrence of severe storm surges and suggest rapid post-storm recovery. The morphological response of the foredune-beach morphology is considered to be a combination of controlling and forcing factors. Process-responses within the system, associated with nearshore interactions and sediment transfer from the littoral drift, are compiled into a multi-scale morphodynamic model. Important to match appropriate dataset to scale of research question or management plan being explored. In the case of management, long-term records of past activity are necessary to predict the future but also to understand natural responses of system to short-term impact such as storm surge

    Transport Items and Physical Internet Handling Boxes: a Comparison Framework Across Supply Chains

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    Pallets, cardboard boxes, and plastic crates are widely used tools to operate supply chains. As such they have many impacts on handling effort, shipment protection, transport mean utilization as well as repositioning and recycling efforts and they represent billions of assets spread all over the world. The historical and local origins of the designs and the sharing among many stakeholders do not ensure at all any kind of global optimization. The purpose of this paper is to define and explain a research effort to better measure and evaluate the efficiencies and inefficiencies for supply chain stakeholders for themselves and globally. When validated the framework will be sued to evaluate new designs on a global scale especially for the design of the handling box related to the Physical Internet concept

    Mapping Client Expectations for Better Business Design Innovation

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    This paper looks at the impacts of customer centricity (business models focused on understanding customer needs) and pull orientation (value chains whose output is dictated by end-user demand rather than producer capacity) on business design innovation in a new economy context. The key concepts are represented as client expectations. These are mapped over a business design framework, showing how they impact all aspects of the business in various ways. The result is a rich yet simple semantic network yielding relations, dependencies and synergies at a glance, based on the co-authors’ Tetrahedral Business Design Framework
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