314 research outputs found
Educing coherent eddy structures in air curtain systems
The work reported here comes within a broader research program dealing with ambiance
separation or confining by means of air curtains (plane air jets). The process is studied
experimentally by Particle Image Velocimetry (PIV). In this paper, the emphasis is put on the
flow structure in the impingement region of such jet systems insofar as it is where transfers
occur preferentially. More precisely, a vortex eduction method was implemented under the
Matlab environment enabling both the automatic detection of 2D coherent patterns embedded
in PIV velocity vector maps, and a statistical analysis of the topological and energy features
of these structures. First, the approach is explained in detail. The second part of this paper is
devoted to its application in the case of plane turbulent impinging simple- and twin-jets for
various jet exit velocities. Results about the size, the shape, the spatial distribution and the
energy content of the detected vortices are provided. Although many questions still remain
open, new insights into the fashion these structures might form, organize and evolve are
given providing an original picture of the plane turbulent impinging jet
Accounting for changes in biodiversity and ecosystem services from a business perspective
Biodiversity refers to the dynamics of interactions between organisms in changing environments. Within the context of accelerating biodiversity loss worldwide, firms are under increasing pressures from stakeholders to develop appropriate tools to account for the nature and consequences of their actions, inclusive of their influences on ecosystem services used by other agents. This paper presents a two-pronged approach towards accounting for changes in biodiversity and ecosystem services from a business perspective. First, we seek to analyze how Environmental Management Accounting (EMA) may be used by firms to identify and account for the interactions between their activities and biodiversity and ecosystem services (BES). To that end, we use dairy farming as a case study and propose general recommendations regarding accounting for changes in biodiversity and ecosystem services from a management accounting perspective. Secondly, after discussing the corporate reporting implications of the main environmental accounting approaches, we propose the underlying principles and structural components of a Biodiversity Accountability Framework (BAF) which would combine both financial and BES data sets; hence, suggesting the need for changes in business accounting and reporting standards. Because this would imply significant changes in business information systems and corporate rating practices, we also underline the importance of making the associated technological, organizational and institutional innovations financially viable. The BAF should be designed as an information base, coconstructed with stakeholders, for setting up and managing new modes of regulation combining tools for mitigating BES loss and remunerating BES supply.Accounting, business, biodiversity, ecosystem services, indicators, management accounting, financial accounting, reporting, corporate social responsibility, standards, biodiversity accountability framework.
Adaptation et Atténuation en Guinée équatoriale, Acteurs et Processus Politiques
The authors analyse the actors and the political process related to the adaptation and the attenuation in Equatorial Guinea
Comparative study of rans turbulence models for impinging jet simulations
Impinging plane jets are flow configurations with applications in many fields. The ability of several turbulence models to simulate this kind of flow was assessed. The numerical results were compared with the data of Cooper et al. (1993) for Re=7.0 104 and a jet nozzle aspect ratio H/D=6, and Re=2.3 104 and H/D=2. The SST, RSM-Δ and RSM-BSL turbulence models were chosen because of their capability to predict flows with high streamline curvature and their expected good accuracy on near wall flow. The results show that the SST and RSM- Δ perform better than the RSM-BSL in the prediction of the mean velocity profiles in the wall-jet and impact zone. The profiles of turbulent energy were particularly difficult to reproduce. All the turbulence models considered here exhibit a similar behavior with respect to the profiles of turbulent energy. The paper shows again the complexity of turbulent impinging jets and the relevant open challenges in CF
Comparative study of rans turbulence models for impinging jet simulations
Impinging plane jets are flow configurations with applications in many fields. The ability of several turbulence models to simulate this kind of flow was assessed. The numerical results were compared with the data of Cooper et al. (1993) for Re=7.0 104 and a jet nozzle aspect ratio H/D=6, and Re=2.3 104 and H/D=2. The SST, RSM-Δ and RSM-BSL turbulence models were chosen because of their capability to predict flows with high streamline curvature and their expected good accuracy on near wall flow. The results show that the SST and RSM- Δ perform better than the RSM-BSL in the prediction of the mean velocity profiles in the wall-jet and impact zone. The profiles of turbulent energy were particularly difficult to reproduce. All the turbulence models considered here exhibit a similar behavior with respect to the profiles of turbulent energy. The paper shows again the complexity of turbulent impinging jets and the relevant open challenges in CF
Accounting for changes in biodiversity and ecosystem services from a business perspective: Preliminary guidelines towards a biodiversity accountability framework
Biodiversity refers to the dynamics of interactions between organisms in changing environments. Within the context of accelerating biodiversity loss worldwide, firms are under increasing pressures from stakeholders to develop appropriate tools to account for the nature and consequences of their actions, inclusive of their influences on ecosystem services used by other agents. This paper presents a two-pronged approach towards accounting for changes in biodiversity and ecosystem services from a business perspective. First, we seek to analyze how Environmental Management Accounting (EMA) may be used by firms to identify and account for the interactions between their activities and biodiversity and ecosystem services (BES). To that end, we use dairy farming as a case study and propose general recommendations regarding accounting for changes in biodiversity and ecosystem services from a management accounting perspective. Secondly, after discussing the corporate reporting implications of the main environmental accounting approaches, we propose the underlying principles and structural components of a Biodiversity Accountability Framework (BAF) which would combine both financial and BES data sets; hence, suggesting the need for changes in business accounting and reporting standards. Because this would imply significant changes in business information systems and corporate rating practices, we also underline the importance of making the associated technological, organizational and institutional innovations financially viable. The BAF should be designed as an information base, coconstructed with stakeholders, for setting up and managing new modes of regulation combining tools for mitigating BES loss and remunerating BES supply
La recherche en sciences humaines et la gestion des aires protégées
Through the case of the southern island of La RĂ©union, we mean to bring a contribution
to the general analysis based on the evolution of population behaviour and the valuation of
actions conducted by the various âresponsiblesâ in order to protect fragilized areas. The
âpracticesâ of coastal territory have evolved during the past generation. The evolution of these
practices in the coast, as a global space and entity, and the increasing feeling of harmful
effects, can be explained in a large part by the evolution of the reunionan sensitiveness
towards environment in general and the sea world in particular; we note a growing and urging
requirement in environmental protection issues, such a demand being sustained by a certain
consciousness about the evolution of marine patrimony. The relative knowledge about coral
and coral reefs value increased, but it has not always been followed by a knowledge of the
role of the lagoon. An anthropological approach is needful; tourism itself must not be analysed
only in terms of socio-economical development, but has to be also considered as a factor
of transformation of the relation to space and territory and the transformation of the âsocial
linkâ; it is through the symbolic exchange operated in the context of tourism in La Reunion
that these evolutions can be achievedAvec l'exemple de La Réunion, nous nous proposons d'apporter une contribution à l'analyse de l'évolution des comportements des populations et à l'évaluation des actions menées par les différents « responsables » pour protéger les
aires fragiles. Les pratiques de l'espace cÎtier ont évolué depuis une génération. L'évolution des pratiques de l'espace cÎtier et du sentiment de nuisance peut s'expliquer en grande partie par l'évolution de la sensibilité des réunionnais quant à l'environnement en général et au milieu
marin en particulier; on constate une exigence de plus en plus affirmée quant à la place de la protection de l'environnement, exigence qui s'appuie sur une certaine conscience de l'évolution du patrimoine marin. Une relative connaissance du corail s'est affirmée, mais elle ne s'accompagne
pas nĂ©cessairement d'une connaissance du rĂŽle du lagon. Une approche anthropologique est nĂ©cessaire; le tourisme lui-mĂȘme ne doit pas ĂȘtre apprĂ©hendĂ© uniquement en termes de dĂ©veloppement socio-Ă©conomique, il est Ă considĂ©rer Ă©galement comme facteur de transformation des rapports Ă l'espace
et au territoire en mĂȘme temps qu'il est facteur de transformation du lien social; c'est Ă travers l'Ă©change symbolique opĂ©rĂ© dans l'espace touristique Ă La RĂ©union que se rĂ©alisent ces Ă©volutions
Les effets conjoints du travail et des horaires alternants sur la santé des agents de surveillance des établissements pénitentiaires
Les prĂ©occupations en santĂ© publique rĂ©vĂšlent le peu Notre Ă©tude vise Ă comparer les effets sur la santĂ© de trois formes dâorganisation temporelle (horaires traditionnels, factions de 6 heures et de 12 heures) au sein dâĂ©tablissements pĂ©nitentiaires français, et plus particuliĂšrement auprĂšs des personnels de surveillance. Des moyens dâinvestigation complĂ©mentaires (questionnaire, observations du travail, traitement statistique) ont Ă©tĂ© mis en Ćuvre pour tenter de faire la part entre le poids des horaires et le poids du travail sur lâĂ©tat de santĂ© des agents. Si les personnels en factions de 12 heures prĂ©sentent des rĂ©sultats meilleurs que les personnels en 6 heures, câest en particulier dĂ» Ă des avantages dans la vie extra-professionnelle, bien que des signes certains de fatigue ne permettent pas de conclure significativement en faveur de telles modalitĂ©s. Au-delĂ de lâalternance des horaires, le contenu du travail pĂšse de maniĂšre importante sur la santĂ© des agents.The aim of our study is to compare the effects of three different forms of time organization (traditional 9 to 5 schedule, 6-hour shifts, and 12-hour shifts) inside French prisons, and particularly on prison guard staff. Complementary means of investigation (questionnaire, work observations, statistical treatment) were used to attempt to evaluate the difference between the effect of working hours and of the actual work on the guardsâ health. Staff who worked 12-hour shifts had more positive results than staff who worked 6-hour shifts. This was mainly due to the advantages in their private lives. At the same time, some signs of fatigue prevent us from conclusively favouring this type of working rhythm. Beyond the alternation of schedules, the actual work content also has an important impact on the workersâ health.Nuestro estudio pretende comparar los efectos sobre la salud de tres formas de organizaciĂłn temporal (horarios tradicionales, turnos de seis horas y de doce horas) en establecimientos penitenciarios franceses, y particularmente en el personal de guardia. Se emplearon mĂ©todos de investigaciĂłn complementarios (cuestionarios, observaciones del trabajo, anĂĄlisis estadĂstico) para intentar diferenciar quĂ© peso tienen respectivamente los horarios y el trabajo propiamente dicho, sobre el estado de salud de los guardianes de cĂĄrceles. El personal que trabaja en turnos de 12 horas presenta mejores resultados que el personal que trabaja en turnos de 6 horas. Este resultado se debe particularmente a las ventajas de este horario en la vida extra-profesional. Sin embargo, los signos claros de fatiga nos impiden estar a favor de tal modalidad. MĂĄs allĂĄ de la alternancia de turnos, el contenido del trabajo pesa de manera significativa sobre la salud de los guardianes de cĂĄrceles
Molécules et NanosystÚmes Multi-émissifs et Photocommutables
The synthesis of photoswitchable emissive molecular system still represents a challenge, in order to develop fluorescence-based devices for nanotechnologies. In the last decade, excitation energy transfer processes (EET) have been advantageously employed to design photoswitchable fluorescent molecular systems between a photochromic dye and an appropriate fluorescent molecule. More recently, photochromic dyes of particular interest, showing no emission in the open-form (P-OF) but a strong emission signal in the closed-form (P-CF), have been developed. Such molecules allow a multi-emission switch when combined with a fluorescent moiety. In this project, we will design and synthesize fluorescent photochromic diarylethene covalently linked to different fluorophores, such as benzothiadiazole (BTD) and BODIPY derivatives. By choosing a fluorophore moiety with blue/green emission (F) and a photochromic moiety with orange/red emission in closed-form (P-CF), EET can occur between F and P-CF leading to photoswitchable multi-emission properties. Photophysical characteristics of dyads will be studied by spectroscopy with the aim of presenting their light-controllable optical properties and the intramolecular EET processes between fluorescent and photochromic moieties.Ce projet de thĂšse consiste dans un premier temps Ă synthĂ©tiser des systĂšmes molĂ©culaires multifonctionnels possĂ©dants un grand nombre dâentitĂ©s fluorescentes et photochromes. De telles architectures nĂ©cessitent ensuite une Ă©tude photophysique poussĂ©e pour caractĂ©riser leurs propriĂ©tĂ©s dâĂ©mission photo-activĂ©e pour jouer le rĂŽle de sondes molĂ©culaires fluorescentes super-rĂ©solutives en imagerie de fluorescence. En effet, lâaccĂšs aux observations nanomĂ©triques par microscopie optique est actuellement un domaine de recherche extrĂȘmement actif et prometteur. Ici, la combinaison astucieuse de molĂ©cules photochromes (de type diarylĂ©thĂšne) et fluorescentes (de type dicyanomĂ©thylĂšne pyranes ou benzophĂ©noxazines) Ă lâĂ©chelle nanomĂ©trique, grĂące Ă des plateformes molĂ©culaires telles que des oligosaccharides et des peptides fonctionnalisĂ©s par âchimie clickâ, doit permettre dâobtenir des structures aux gĂ©omĂ©tries variĂ©es avec des distances et orientations inter-chromophores diverses, dont lâoptimisation doit conduire Ă des interactions efficaces menant Ă lâĂ©mergence dâeffets collectifs coopĂ©ratifs. Pour ces assemblages molĂ©culaires mixtes, il est attendu que la prĂ©sence dâune unitĂ© photochrome puisse engendrer lâextinction de fluorescence de plusieurs fluorophores lorsque ces entitĂ©s sont situĂ©es Ă une distance appropriĂ©e pour que le transfert dâĂ©nergie ait lieu de maniĂšre amplifiĂ©e. Par ailleurs, mĂȘme une faible conversion des photochromes doit permettre dâatteindre un contraste de fluorescence extrĂȘmement efficace avoisinant 100% et ainsi obtenir des super-molĂ©cules dont la photo-commutation serait rapide et Ă©conome en photons. Il sâagira enfin de dĂ©montrer que les systĂšmes molĂ©culaires multichromophoriques ainsi optimisĂ©s prĂ©sentent le comportement souhaitĂ© Ă lâĂ©chelle de la molĂ©cule unique pour lâimagerie de fluorescence super-rĂ©solution
Cartographier la vulnérabilité aux variations climatiques : une méta-analyse en Afrique
CIFOR, Bogor, IndonesiaLa variabilitĂ© climatique a toujours affectĂ© la sociĂ©tĂ© et le changement climatique anthropique constitue un dĂ©fi supplĂ©mentaire pour les populations et leurs activitĂ©s, en particulier en Afrique. Parmi les diffĂ©rents outils disponibles pour l'Ă©valuation de la vulnĂ©rabilitĂ© de la sociĂ©tĂ© aux variations climatiques, l'utilisation d'indices quantifiĂ©s de vulnĂ©rabilitĂ© et leur cartographie se sont particuliĂšrement dĂ©veloppĂ©es ces derniĂšres annĂ©es. L'objectif de ce document est de passer en revue des cartes de vulnĂ©rabilitĂ© Ă l'Ă©chelle du continent africain afin de rĂ©pondre aux questions suivantes : parmi la diversitĂ© des indices et des cartes de vulnĂ©rabilitĂ©, est-il possible de distinguer des groupes prĂ©sentant des traits communs, par exemple identifiant les mĂȘmes zones fortement vulnĂ©rables ? Comment expliquer les diffĂ©rences entre les cartes ? OĂč se trouvent les zones les plus vulnĂ©rables en Afrique selon chaque groupe de cartes ? Ă partir de l'analyse de 23 indices, nous avons dĂ©gagĂ© quatre groupes d'indices corrĂ©lĂ©s. Chaque groupe fournit une image diffĂ©rente de la vulnĂ©rabilitĂ©, orientĂ©e vers la pauvretĂ© et la dĂ©pendance Ă l'agriculture, vers la densitĂ© de la population, vers la richesse et les capitaux non agricoles ou vers les failles de gouvernance. Les zones les plus vulnĂ©rables varient selon les groupes, qui vĂ©hiculent des messages contrastĂ©s sur les prioritĂ©s d'adaptation. Les contrastes entre ces groupes s'expliquent par les diffĂ©rentes conceptualisations de la vulnĂ©rabilitĂ© et les diffĂ©rentes mĂ©thodes d'Ă©valuation, y compris le choix des indicateurs. Les divergences sur la localisation des zones fortement vulnĂ©rables montrent les difficultĂ©s dans l'utilisation des cartes pour les dĂ©cisions politiques. Il est important que les dĂ©cideurs identifient clairement les prĂ©supposĂ©s de chaque indice et apprĂ©hendent la diversitĂ© des indices et leurs rĂ©sultats
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