195 research outputs found

    Mitigation of Extreme Heat and Sustainable Cooling

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    The last 5 years have seen the hottest weather on record with many countries experiencing exceptionally warm spells. Extreme heat impacts on health, productivity and economics and the impact is greatest in cities and it dis-proportionally affects the urban poor. This paper initially gives data on global temperature change, as well as the prevalence and impact of extreme heat in cities. To help cities mitigate the impacts of extreme heat the Adrienne Arsht-Rockefeller Foundation Resilience Center and the Extreme Heat Resilience Alliance in collaboration with the UN Environment Programme, the Cool Coalition, RMI, the Global Covenant of Mayors for Climate and Energy, Mission Innovation and the World Economic Forum’s Global Commission on BiodiverCities by 2030 are developing a toolkit for city officials. This paper describes the toolkit called the Heat Action Platform. The Heat Action Platform is a living, engagement-oriented tool for city officials, practitioners, and financial institutions to find guidance, both existing resources and tailor-made solutions, on reducing the human and economic impacts of extreme heat at the regional or municipal level. The platform offers opportunities to engage with world-leading experts across a diversity of disciplines to plan, fund, implement, and measure heat resilience actions. The paper describes the rationale behind the heat action platform, its development and how it is being used to mitigate the impacts of extreme heat. Future opportunities to collaborate are identified

    Effet magnéto-optique et optique des couches minces à base de ferrite de cobalt

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    Cette étude a pour but la mesure des effets magnéto-optiques (rotation Faraday) en fonction du champ magnétique appliqué et en fonction de la longueur d’onde, ainsi que la mesure de la transmittance (effet optique) des couches minces à base de ferrite de cobalt. Les résultats montrent une forte rotation Faraday spécifique avec des cycles d'hystérésis et des spectres de transmittance d'une bonne transparence dans la gamme Télécom (≈1550 nm).Mots-clés: ferrite de cobalt, sol-gel, couches minces, rotation Faraday, transmittance. Magneto-optical effect and optical thin films cobalt ferriteThis study was designed to measure the magneto-optical effect (Faraday rotation) according to the applied magnetic field and a function of the wavelength and the transmittance measurement (optical effect) thin film based on cobalt ferrite. The results show a high specific Faraday rotation with hysteresis cycles and transmittance spectra of a good transparency in the range Telecom (≈1550 nm).Keywords: cobalt ferrite, sol-gel thin films, Faraday rotation, transmittance

    Etude des propriétés magnéto-optiques des couches minces à base de ferrite de cobalt obtenues par voie sol-gel

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    Ce travail est consacré à l'étude des propriétés magnéto-optiques (rotation Faraday) de couches minces à base de ferrite de cobalt obtenues par voie sol-gel. La contribution de la méthode sol-gel utilisée est très importante et cela permet d’obtenir des couches minces ayant une bonne qualité optique. Cette démarche nécessite juste l’utilisation de liquides magnétiques ou ferro fluides, de précurseurs de silice (pas cher) et d’un substrat de verre. Le but est d’obtenir des couches minces et étudier leurs propriétés magnéto-optiques. Les courbes obtenues à la longueur d’onde de 820 nm présentent des cycles d’hystérésis avec des rotations rémanentes de 40, 60 et 81°/cm. Ces résultats présentent une excellente rotation Faraday de 212, 318 et 340°/cm à la longueur d’onde de 820 nm. Ceci montre la forte potentialité de la matrice sol-gel dopée.Mots-clés: nanoparticules magnétiques, ferrite de cobalt, sol-gel, couches minces, rotation Faraday. Study of themagneto-optical properties of thin films cobalt ferrite obtainedby the sol-gel This work is devoted to the study of magneto-optical (Faraday rotation) of thin cobalt ferrite layers obtained by sol-gel. The contribution of the sol-gel method is very important and it allows obtaining thin film shaving a good optical quality. This requires only the use of magnetic fluids or ferro fluids, silica precursors (cheap) and a glass substrate. The goal is to obtain thin layers and study their magneto-optical properties. The curves obtained for the wave length of 820 nm have hysteresis loops with retentive rotations of 40, 60 and 81°/ cm. These results show excellentFaradayrotation 212, 318 and 340°/cm ata wave length of 820 nm. This shows the high potential of the doped sol-gel matrix.Keywords: agnetic nanoparticles, cobalt ferrite, sol-gel, thin films, Faraday rotation

    Conception, réalisation et caractérisation d'inductances planaires à couches magnétiques

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    Ce travail de thèse concerne la miniaturisation et l intégration de composants magnétiques comme les inductances utilisées dans les convertisseurs DC-DC et les circuits haute fréquence. Cette thèse a pour objectifs : - de développer une méthodologie d étude des inductances à couches magnétiques - de montrer la faisabilité de tels composants utilisant des couches épaisses de ferrite (50 à 500 m). Le contenu de notre document s articule ainsi autour de trois axes : la simulation, la réalisation et la caractérisation. En simulation, le logiciel HFSS, nous a permis de concevoir, de prédire le comportement du composant et d'étudier l influence des différents entrefers et épaisseurs du matériau magnétique. La réalisation fait appel aux différentes et nombreuses étapes micro technologiques qui sont décrites en détail. Ces étapes concernent les techniques de dépôt sous vide, les procédés de photolithographie, les techniques de dépôt électrolytique, les techniques de sciage et de collage. Enfin, la caractérisation des inductances réalisées a été effectuée en basses, moyennes et hautes fréquences respectivement au LCR mètre (20Hz à 1MHz), à l impédance mètre (40Hz à 110MHz) et à l analyseur vectoriel de réseaux (10MHz à 67GHz)This thesis concerns the miniaturization and integration of magnetic components such as inductors used in DC-DC converters and high frequency circuits. This thesis aims to: - to develop a methodology for the study of magnetic layers inductors; - to show the feasibility of such components using thick layers of ferrite (50 to 500 m). The content of our document is structured around three axes: simulation, realization and characterization. In simulation, HFSS software allowed us to design, predict the behavior of the component and to study the influence of different air gaps and layers of magnetic material. The realization involves numerous and different micro technology steps which are described in detail. These steps are technical of vacuum deposition, photolithography processes, electroplating deposition techniques, techniques of sawing and sticking. Finally, the characterization of inductors achieved was done in low, medium and high frequencies respectively with a LCR meter (20Hz to 1MHz), an impedance meter (40Hz to 110MHz) and a vector network analyzer (10MHz to 67GHz)ST ETIENNE-Bib. électronique (422189901) / SudocSudocFranceF

    On a bi-layer shallow-water problem

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    Abstract In this paper, we prove an existence and uniqueness result for a bi-layer shallow water model in depth-mean velocity formulation. Some smoothness results for the solution are also obtained. In a previous work we proved the same results for a one-layer problem. Now the di culty arises from the terms coupling the two layers. In order to obtain the energy estimate, we use a special basis which allows us to bound these terms.

    Structural Characterization of Magnetic Nano-particles Suspensions, Using Magnetic Measurements

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    P curves, Magnetic fluids, Ferrofluids, Nanostructural characterization, Magnetic powders, Hysteresis curve, Magnetic nanocomposite materialsThe paper describes some characteristics of the “P” curves for structural characterization of magnetic nano-particles suspensions (complex fluids, complex powders, complex composite materials, or living biological materials having magnetic properties). In the case of these materials, the magnetic properties are conferred to various carrier liquids by artificially integrating in their structure ferromagnetic particles of different sizes. The magnetic properties are usually shown by the hysteresis curve. The structure can be seen on (electronic) micrography. The P curves offer another possibility to determine the structure of the magnetic component of a complex fluid by numerical analysis of the magnetization curve experimentally obtained. The paper presents a detailed approach of the P curves and some limitations in their use

    Sn1-xBixO2 and Sn1-xTaxO2 (0 \leq x \leq 0.75): A first-principles study

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    The structural, elastic, electronic and optical (x = 0) properties of doped Sn1-xBixO2 and Sn1-xTaxO2 (0 \leq x \leq 0.75) are studied by using the first-principles pseudopotential plane-wave method within the local density approximation. The independent elastic constants Cij and other elastic parameters of these compounds have been calculated for the first time. The mechanical stability of the compounds with different doping concentrations has also been studied. The electronic band structure and density of states are calculated and the effect of doping on these properties is also analyzed. It is seen that the band gap of the undoped compound narrowed with dopant concentration which disappeared for x = 0.26 for Bi doping and 0.36 for Ta doping. The materials thus become conductive oxides through the change in the electronic properties of the compound for x \leq 0.75 which may be useful for potential application. The calculated optical properties, e.g. dielectric function, refractive index, absorption spectrum, loss-function, reflectivity and conductivity of the undoped SnO2 in two polarization directions are compared with both previous calculations and measurements. Keywords: Doped SnO2; First-principles; Mechanical properties; Electronic band structure; Optical properties.Comment: 10 pages, 5 figures, added 10 more references, comparison with mearements mad

    A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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    Atmospheric Pressure Chemical Vapour Deposition of Fluorine-doped Tin(IV) Oxide from Fluoroalkyltin Precursors

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    Perfluoroalkytin compounds R(4-n)Sn(Rf)n (R = Me, Et, Bu, Rf = C4F9, n = 1; R = Bu, Rf = C4F9, n = 2, 3; R = Bu, Rf = C6F13, n = 1) have been synthesised, characterised by 1H, 13C, 19F and 119Sn NMR and evaluated a precursors for the atmospheric pressure CVD (APCVD) of F-doped SnO2 thin films. All precursors were sufficiently volatile at in the range 84 – 136oC and glass substrate temperatures of ca. 550oC to yield high quality films with ca. 0.79 – 2.02% fluorine incorporation, save for Bu3SnC6F13 which incorporated < 0.05% fluorine. Films were characterised by XRD, SEM, thickness, haze, emissivity, sheet resistance. The fastest growth rates and highest quality films were obtained from Et3SnC4F9. An electron diffraction study of Me3SnC4F9 revealed four conformations of which only the two of lowest abundance showed close F…Sn contacts which could plausibly be associated with halogen transfer to tin and in each case it was fluorine attached to either the γ- or δ-carbon atoms of the Rf chain

    Définition d'une solution de photogrammétrie par drone aérien : cahier des charges et protocoles de validation

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    Photogrammetry is a methodology which uses the characteristics of reproducing the parallax for the relief, so the third dimension. UAVs allow boarding instrumentation via an air carrier. The coupling of these two concepts gives the idea of photogrammetry by drone. In this thesis, will be presented the arguments leading to the achievement of an effective drone vector, and all the methodology needed for the performance of the solution. From protocols choice of instrumentation to the validation of the solution, through all procedures for individual validation, implementation and control. All leading to dronistique operatively photogrammetry solution, dispensing with the use of ground control point and control their behavior using a dedicated protocol. This internship was made in the context of entrepreneurship.La photogrammétrie est une méthodologie qui utilise les caractéristiques de la parallaxe pour reproduire le relief, donc la 3e dimension. Les drones permettent l'embarquement d'instrumentation via un vecteur aérien. L'accouplement de ces 2 concepts donne l'idée de la photogrammétrie par drone. Au cours de ce mémoire, seront présentés les raisonnements conduisant à la réalisation d'un vecteur drone efficace, et toute la méthodologie nécessaire aux fonctions de photogrammétrie, allant des protocoles de choix de l'instrumentation à la validation de la solution en passant par toutes les procédures de validation individuelles, de mise en œuvre et de contrôle. Le tout conduisant à une solution dronistique de photogrammétrie opérationnelle, s'affranchissant de l'utilisation de point d'appui et s'autocontrôlant grâce à un protocole dédié. Ce TFE a été effectué dans le contexte d'une création d'entreprise
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