Validation of the computational fluid–structure interaction simulation at real-scale tests of a flexible 29 m umbrella in natural wind flow

The sensitivity of membrane structures to wind loads due to their flexibility and small inertial masses raises the question of their behavior under natural wind conditions. Particularly transient wind loads could lead to dynamic amplification of the structural response. The assessment of the dynamic response of membrane structures is complex due to their special load carrying behavior, their material properties, and their distinct structural interaction with flow induced effects. Computationally intensive fluid–structure interaction simulation could overcome simplifications and limitations of existing approaches, especially small scale wind tunnel tests, and allow the assessment of all relevant structural and fluid phenomena. This paper outlines a virtual design methodology for lightweight flexible membrane structures under the impact of fluctuating wind loads and provides results on the unique validation of the method at real-scale tests of a highly flexible 29 m umbrella

Ecological Modeling of Aedes aegypti (L.) Pupal Production in Rural Kamphaeng Phet, Thailand

Background - Aedes aegypti (L.) is the primary vector of dengue, the most important arboviral infection globally. Until an effective vaccine is licensed and rigorously administered, Ae. aegypti control remains the principal tool in preventing and curtailing dengue transmission. Accurate predictions of vector populations are required to assess control methods and develop effective population reduction strategies. Ae. aegypti develops primarily in artificial water holding containers. Release recapture studies indicate that most adult Ae. aegypti do not disperse over long distances. We expect, therefore, that containers in an area of high development site density are more likely to be oviposition sites and to be more frequently used as oviposition sites than containers that are relatively isolated from other development sites. After accounting for individual container characteristics, containers more frequently used as oviposition sites are likely to produce adult mosquitoes consistently and at a higher rate. To this point, most studies of Ae. aegypti populations ignore the spatial density of larval development sites. Methodology - Pupal surveys were carried out from 2004 to 2007 in rural Kamphaeng Phet, Thailand. In total, 84,840 samples of water holding containers were used to estimate model parameters. Regression modeling was used to assess the effect of larval development site density, access to piped water, and seasonal variation on container productivity. A varying-coefficients model was employed to account for the large differences in productivity between container types. A two-part modeling structure, called a hurdle model, accounts for the large number of zeroes and overdispersion present in pupal population counts. Findings - The number of suitable larval development sites and their density in the environment were the primary determinants of the distribution and abundance of Ae. aegypti pupae. The productivity of most container types increased significantly as habitat density increased. An ecological approach, accounting for development site density, is appropriate for predicting Ae. aegypti population levels and developing efficient vector control program

Mutations de l'agriculture en Asie du Sud-Est

L'histoire économique de la Thaïlande au cours des dernières décennies présente de fortes articulations entre les secteurs agricole et industriel. Si celles-ci se sont renforcées à partir du milieu des années 1980, il semble que le point de rupture soit aujourd'hui atteint. La poursuite du modèle de développement industriel se heurte à l'augmentation rapide des coûts du travail, aux dynamiques spécifiques du secteur agricole, ou à la mobilité d'une force de travail d'origine rurale peu éduquée. Ces contraintes structurelles conduisent à s'interroger sur la capacité des familles rurales à perpétuer leur fonction de filet social et celle du secteur agricole à réguler les fluctuations du marché du travail dans un contexte de crise conjoncturelle d'importance comme celle qu'a récemment connue la Thaïlande. (Résumé d'auteur

L'industrialisation thaïlandaise confrontée à la mobilité de la main-d'oeuvre

Cet article examine, à la lumière de résultats d'enquêtes réalisées dans les régions périphériques de Thaïlande en cours d'industrialisation rapide, les contraintes à la pérennité du modèle actuel de la croissance thaïlandaise. La capacité de l'agriculture à retenir la main-d'oeuvre est un des freins à son intégration dans le processus d'industrialisation. Deux facteurs expliquent le maintien de près de 60% de la population active dans l'agriculture : les mobilités sectorielles et spatiales (dont la pluri-activité) et les ajustements des systèmes agraires (par intensification et diversification des productions). A l'insuffisante disponibilité d'une main-d'oeuvre qualifiée, s'ajoutent aujourd'hui pour le secteur industriel des difficultés à satisfaire ses besoins en force de travail peu qualifiée, malgré l'appui des politiques publiques visant à favoriser l'accès à des réservoirs supposés importants de main-d'oeuvre rurale. La réponse entrepreneuriale au manque de main-d'oeuvre industrielle et à sa forte instabilité évite les augmentations des salaires de base mais n'aborde pas les facteurs qui permettraient une augmentation de la production du travail comme celle de la valeur ajoutée industrielle à l'heure où la Thaïlande est confrontée à l'érosion de sa compétitivité sur les marchés mondiaux. (Résumé d'auteur

Croissance industrielle et redéploiement spatial en Thaïlande

Les mesures publiques dirigées vers le secteur industriel en Thaïlande ont pour objectif affiché de redresser les déséquilibres intérieurs sociaux et spatiaux et de maintenir la présence des entreprises thaïlandaises sur les marchés mondiaux. C'est dans un contexte original de montée en puissance des entrepreneurs dans l'élaboration des politiques que se situe l'appréciation des effets des interventions publiques d'appui au secteur privé. La conciliation des impératifs du déséquilibrage de l'espace national et de la politique industrielle, jointe à l'alliance privé/public, a contribué à dupliquer le modèle de déséquilibre spatial que l'intervention étatique était supposée réduire. L'analyse de l'impact des mesures publiques dans deux régions périphériques met en exergue leur limitations et l'importance de facteurs complémentaires. L'évolution des relations privé/public dans l'élaboration des politiques industrielles et de leur conception du territoire, de même que la transformation de l'économie régionale et mondiale expliquent les tendances aujourd'hui observables dans le processus d'industrialisation des régions périphériques. (résumé d'auteur

Assessing an evidence-based intervention for spouse caregivers of persons with Alzheimer’s disease: results of a community implementation of the NYUCI in Israel

Objectives: Alzheimer’s disease (AD) affects not only the person with the illness, but family caregivers as well. The NYU Caregiver Intervention (NYUCI), a psychosocial intervention which has demonstrated both short and long-term benefits for caregivers, has been used widely in the United States and in Australia and England. The Israeli study was a hybrid between a community implementation study and a randomized controlled trial (RCT) of the NYUCI in a non-English speaking country. Method: A sample of 100 spouse caregivers participated in trial comparing the NYUCI provided by ten Israeli clinicians (enhanced care), to support group participation (usual care). The major outcome of interest was caregiver depressive symptoms, measured with the Geriatric Depression Scale. A linear random effects regression model controlling for factors associated with depressive symptoms was used to plot the longitudinal trajectories of depressive symptoms over the two-year study period and compare outcomes for the enhanced care and control groups. Results: One hundred spouse caregivers enrolled, of whom 81 provided data at baseline and at one or more post intervention assessments. The Israeli adaptation of the NYUCI was effective in reducing depressive symptoms reported by caregivers compared to their counterparts in the control group, b= −1.29 [95%CI (−2.43, −0.15)], p= .0265. Conclusion: While implementing a randomized controlled trial of an intervention developed and tested in traditional research settings using community providers in Israel, posed unique challenges, the study demonstrated benefits to caregivers. As a result, 30 municipalities in Israel are currently implementing an ongoing adaptation of the NYUCI

Thermal modeling and optimization of a thermally matched energy harvester

International audienceThe interest in energy harvesting devices has grown with the development of wireless sensors requiring small amounts of energy to function. The present article addresses the thermal investigation of a coupled piezoelectric and bimetal-based heat engine. The thermal energy harvester in question converts low-grade heat flows into electrical charges by achieving a two-step conversion mechanism for which the key point is the ability to maintain a significant thermal gradient without any heat sink. Many studies have previously focused on the electrical properties of this innovative device for energy harvesting but until now, no thermal modeling has been able to describe the device specificities or improve its thermal performances. The research reported in this paper focuses on the modeling of the harvester using an equivalent electrical circuit approach. It is shown that the knowledge of the thermal properties inside the device and a good comprehension of its heat exchange with the surrounding play a key role in the optimization procedure. To validate the thermal modeling, finite element analyses as well as experimental measurements on a hot plate were carried out and the techniques were compared. The proposed model provided a practical guideline for improving the generator design to obtain a thermally matched energy harvester that can function over a wide range of hot source temperatures for the same bimetal. A direct application of this study has been implemented on scaled structures to maintain an important temperature difference between the cold surface and the hot reservoir. Using the equations of the thermal model, predictions of the thermal properties were evaluated depending on the scaling factor and solutions for future thermal improvements are presented