225 research outputs found

    High resolution modelling of aerosol dispersion regimes during the CAPITOUL field experiment: from regional to local scale interactions

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    High resolution simulation of complex aerosol particle evolution and gaseous chemistry over an atmospheric urban area is of great interest for understanding air quality and processes. In this context, the CAPITOUL (Canopy and Aerosol Particle Interactions in the Toulouse Urban Layer) field experiment aims at a better understanding of the interactions between the urban dynamics and the aerosol plumes. During a two-day Intensive Observational Period, a numerical model experiment was set up to reproduce the spatial distribution of specific particle pollutants, from the regional scales and the interactions between different cities, to the local scales with specific turbulent structures. Observations show that local dynamics depends on the day-regime, and may lead to different mesoscale dynamical structures. This study focuses on reproducing these fine scale dynamical structures, and investigate the impact on the aerosol plume dispersion. The 500-m resolution simulation manages to reproduce convective rolls at local scale, which concentrate most of the aerosol particles and can locally affect the pollutant dispersion and air quality

    Towards a pivotal-based approach for business process alignment.

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    This article focuses on business process engineering, especially on alignment between business analysis and implementation. Through a business process management approach, different transformations interfere with process models in order to make them executable. To keep the consistency of process model from business model to IT model, we propose a pivotal metamodel-centric methodology. It aims at keeping or giving all requisite structural and semantic data needed to perform such transformations without loss of information. Through this we can ensure the alignment between business and IT. This article describes the concept of pivotal metamodel and proposes a methodology using such an approach. In addition, we present an example and the resulting benefits

    Comparison of energy consumption and costs of different HEVs and PHEVs in European and American context

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    This paper will analyse on the one hand the potential of Plug in Hybrid electric Vehicles to significantly reduce fuel consumption and displace it torward various primary energies thanks to the electricity sector. On the other hand the total cost of ownership of two different PHEV architectures will be compared to a conventional cehicle and a HEV without external charging

    Conception de systèmes par applications de modèles paramétrés

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    National audienceNous présentons nos travaux sur les composants de modèle et leur opérateur associé "apply" qui permet la conception de systèmes par assemblage de composants de modèles (rangés dans des bibliothèques). Nous illustrons ces travaux à l'aide d'un outil démonstrateur "CocoaModeler". Cet atelier UML 2 étendu aux composants de modèles supporte des chaînes de production flexibles selon différentes stratégies de ciblage et différentes plates-formes technologiques

    What is the smallest physically acceptable scale for 1D turbulence schemes?

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    In numerical weather prediction (NWP) models, at mesoscale, the subgrid convective boundary-layer turbulence is dominated by the uni-directional (1D) vertical thermal production. In Large-Eddy Simulations (LES), the thermal plumes are resolved and the residual subgrid turbulent motions are homogeneous and isotropic, thus three-dimensional (3D), resulting from the dynamical production.This article sets the critical horizontal resolution for which the usually 1D turbulence schemes of NWP models must be replaced by 3D turbulence schemes. LES from five dry and cumulus-topped free convective boundary layers and one forced convective boundary layer are performed. From these LES data, the thermal production and vertical and horizontal dynamicalproductions are calculated at several resolutions from LES to mesoscale. It appears that the production terms of both dry and cumulus-topped free convective boundary layers have the same behavior. A pattern emerges whenever data are ranked by the resolution scaled by the size of thermal plumes, (h + hc , where h is the boundary-layer height and hc is the depth of the cloud layer). In free onvective boundary layers, the critical horizontal resolution for which the horizontal motions must be represented is 0.5(h + hc ). However, the critical horizontal resolution in the forced convective boundary layer case is 3(h + hc )

    The use of the scintillation technique for monitoring seasonal water consumption of olive orchards in a semi-arid region

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    To monitor seasonal water consumption of agricultural fields at large scale, spatially averaged surface fluxes of sensible heat (H) and latent heat (LvE) are required. The scintillation method is shown to be a promising device for obtaining the area-averaged sensible heat fluxes, on a scale of up to 10 km. These fluxes, when combined with a simple available energy model, can be used to derive area-averaged latent heat fluxes. For this purpose, a Large Aperture Scintillometer (LAS) was operated continuously for more than one year over a tall and sparse irrigated oliveyard located in south-central Marrakesh (Morocco). Due to the flood irrigation method used in the site, which induces irregular pattern of soil moisture both in space and time, the comparison between scintillometer-based estimates of daily sensible heat flux (HLAS) and those measured by the classical eddy covariance (EC) method (HEC) showed a large scatter during the irrigation events, while a good correspondence was found during homogenous conditions (dry conditions and days following the rain events). We found, that combining a simple available energy model and the LAS measurements, the latent heat can be reliably predicted at large scale in spite of the large scatter (R2 = 0.72 and RMSE = 18.25Wm2) that is obtained when comparing the LAS against the EC. This scatter is explained by different factors: the difference in terms of the source areas of the LAS and EC, the closure failure of the energy balance of the EC, and the error in available energy estimates. Additionally, the irrigation efficiency was investigated by comparing measured seasonal evapotranspiration values to those recommended by the FAO. It was found that the visual observation of the physical conditions of the plant is not sufficient to efficiently manage the irrigation, a large quantity of water is lost (37% of total irrigation). Consequently, the LAS can be considered as a potentially useful tool to monitor the water consumption in complex conditions

    Global variations in pubertal growth spurts in adolescents living with perinatal HIV

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    Objective: To describe pubertal growth spurts among adolescents living with perinatally acquired HIV (ALWPHIV) on antiretroviral therapy (ART).Design: Observational data collected from 1994 to 2015 in the CIPHER global cohort collaboration.Methods: ALWPHIV who initiated ART age less than 10 years with at least four height measurements age at least 8 years were included. Super Imposition by Translation And Rotation (SITAR) models, with parameters representing timing and intensity of the growth spurt, were used to describe growth, separately by sex. Associations between region, ART regimen, age, height-for-age (HAZ), and BMI-for-age z-scores (BMIz) at ART initiation (baseline) and age 10 years, and SITAR parameters were explored.Results: Four thousand seven hundred and twenty-three ALWPHIV were included: 51% from East and Southern Africa (excluding Botswana and South Africa), 17% Botswana and South Africa, 6% West and Central Africa, 11% Europe and North America, 11% Asia-Pacific, and 4% Central, South America, and Caribbean. Growth spurts were later and least intense in sub-Saharan regions. In females, older baseline age and lower BMIz at baseline were associated with later and more intense growth spurts; lower HAZ was associated with later growth spurts. In males, older baseline age and lower HAZ were associated with later and less intense growth spurts; however, associations between baseline HAZ and timing varied by age. Lower HAZ and BMIz at 10 years were associated with later and less intense growth spurts in both sexes.Conclusion: ALWPHIV who started ART at older ages or already stunted were more likely to have delayed pubertal growth spurts. Longer-term follow-up is important to understand the impact of delayed growth

    Global variations in pubertal growth spurts in adolescents living with perinatal HIV

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    Objective: To describe pubertal growth spurts among adolescents living with perinatally acquired HIV (ALWPHIV) on antiretroviral therapy (ART).Design: Observational data collected from 1994 to 2015 in the CIPHER global cohort collaboration.Methods: ALWPHIV who initiated ART age less than 10 years with at least four height measurements age at least 8 years were included. Super Imposition by Translation And Rotation (SITAR) models, with parameters representing timing and intensity of the growth spurt, were used to describe growth, separately by sex. Associations between region, ART regimen, age, height-for-age (HAZ), and BMI-for-age z-scores (BMIz) at ART initiation (baseline) and age 10 years, and SITAR parameters were explored.Results: Four thousand seven hundred and twenty-three ALWPHIV were included: 51% from East and Southern Africa (excluding Botswana and South Africa), 17% Botswana and South Africa, 6% West and Central Africa, 11% Europe and North America, 11% Asia-Pacific, and 4% Central, South America, and Caribbean. Growth spurts were later and least intense in sub-Saharan regions. In females, older baseline age and lower BMIz at baseline were associated with later and more intense growth spurts; lower HAZ was associated with later growth spurts. In males, older baseline age and lower HAZ were associated with later and less intense growth spurts; however, associations between baseline HAZ and timing varied by age. Lower HAZ and BMIz at 10 years were associated with later and less intense growth spurts in both sexes.Conclusion: ALWPHIV who started ART at older ages or already stunted were more likely to have delayed pubertal growth spurts. Longer-term follow-up is important to understand the impact of delayed growth
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