• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 57
  • 41
  • 38
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 169
  • 169
  • 37
  • 24
  • 23
  • 22
  • 16
  • 16
  • 15
  • 14
  • 13
  • 13
  • 12
  • 11
  • 11
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Sentenças absolutas no português brasileiro infantil: um estudo experimental / Absolutive sentences in child Brazilian Portuguese: an experimental study

Camilla de Rezende 31 August 2016 (has links)
Esta dissertação é resultado de uma pesquisa que investigou o comportamento linguístico de crianças falantes nativas de português brasileiro com relação a sentenças absolutas, que consistem em uma alternância na valência de verbos transitivos encontrada especificamente no PB, tal como Eu aperto esse botão [do videogame] e, olha lá, a bola chutou. Segundo Negrão & Viotti (2010), nas absolutas o argumento que representaria a energia responsável pela causa do evento não está presente e nem chega a ser conceitualizado. Não há, portanto, a presença de uma força indutora (Negrão & Viotti, 2010). Desenvolvemos dois experimentos: um de tarefa de produção eliciada e outro de julgamento de aceitabilidade. Nossas previsões são: (a) as absolutas serão mais produzidas com a ausência da força indutora, que seria o argumento agente; (b) alguns verbos proporcionarão mais a produção de absolutas que outros, por estarem mais propensos à supressão da força indutora; e (c) crianças produzirão mais absolutas do que passivas visto que as absolutas são menos complexas estruturalmente. As condições testadas foram: presença/ausência de um agente e tipo de verbo (mais ou menos propenso à supressão do agente). Os resultados sugerem que ambas as condições influenciaram nas respostas dos participantes, de modo que os contextos sem agente e os contextos com verbos mais propensos à supressão do agente se mostraram mais propícios às sentenças absolutas. Por fim, as crianças mais novas testadas produziram mais absolutas do que passivas, o que indica que a absoluta, por ser menos complexa, é uma estrutura mais acessível às crianças. / This dissertation is the result of a research that has investigated the linguistic behavior of Brazilian Portuguese speaking children in relation to absolutive sentences, which consist of a verb valency alternation found specifically in BP, such as Eu aperto esse botão [do videogame] e, olha lá, a bola chutou (I press this button [in the videogame] and, look, the ball kicked [in the sense that the ball was kicked]). According to Negrão & Viotti (2010), in the absolutive constructions, the argument that would represent the energy responsible for the cause of the event is not present. Actually, it is not even conceptualized. Therefore, there is no driving force (Negrão & Viotti, 2010). We developed two experiments: an elicited production task and an acceptability judgment task. Our predictions are: (a) the absolutive sentences will be produced more often in contexts without a driving force, which would be, in this case, the agent; (b) more absolutive sentences will be produced with some verbs than others, because they are more likely to suppress the driving force; and (c) children will produce more absolutive constructions than passives since the absolutive construction is structurally simpler. The tested conditions were: presence/absence of an agent and verb type (more or less likely to suppress the agent). The results suggest that both conditions influenced participants answers, so that the contexts without an agent and the contexts with verbs more likely to suppress the agent were more supportive environments for the absolutive constructions. Finally, the younger children we tested produced more absolutive constructions than passives, which indicates that, as a less complex structure, the absolutive is more accessible to children.
112

Efeitos de inibidor de protease sobre os epitélios de revestimento e glandular do rato / Effects of protease inhibitors on epithelial tissues and salivar glands of rats

Fabiano Misael Cavenaghi 26 November 2009 (has links)
O tratamento anti-HIV conhecido como HAART (Highly Active Antiretroviral Therapy) se tornou comum por volta de 1996, e utiliza 3 ou 4 diferentes medicamentos em combinação - geralmente dois inibidores de transcriptase reversa + 1 ou 2 inibidores de protease. A introdução desse tipo de tratamento trouxe um grande impacto na morbidade e mortalidade de indivíduos infectados pelo HIV. Os inibidores de protease (PIs) são uma boa alternativa às falhas terapêuticas observadas com o uso dos inibidores de transcriptase reversa, no entanto também são associados a vários efeitos tóxicos, como desconforto abdominal, vômito, diarréia, dor de cabeça, tontura, lipodistrofia, hipercolesterolemia, hipertrigliceridemia e hiperglicemia. Em função da existência de efeitos adversos e da condição do ritonavir como protótipo desse tipo de medicação, nosso objetivo é avaliar o efeito desse medicamento sobre os epitélios de revestimento e glandular relacionados à cavidade bucal, de forma a identificar a possibilidade da existência de complicações bucais relacionadas ao uso de inibidores de protease. Ratos albinos (Wistar) foram tratados com Ritonavir (10mg/Kg) por períodos de 4 e 8 semanas. Foram avaliadas as taxas séricas de triglicérides e colesterol (total, HDL, LDL, VLDL). Ao final dos períodos de tratamentos propostos, os animais foram sacrificados, e as peças utilizadas no estudo foram colhidas, (sangue, pele, língua, palatos e glândulas salivares). O sangue coletado foi imediatamente centrifugado sendo o plasma foi utilizado para avaliação das lipoproteínas. Os tecidos colhidos foram fixados, descalcificados quando necessário, processados para inclusão em parafina, cortados com 6µm de espessura, montados em slides e corados com hematoxilina e eosina, para avaliação histopatológica, morfométrica e estereológica. Os dados colhidos foram apresentados em valores médios, e as diferenças analisadas por testes estatísticos adequados para a comparação entre as amostras. Nossos resultados mostram pequenas variações nas características morfológicas de epitélios de revestimento e glandulares, variações essas que poderiam deixar esses tecidos mais propensos a sofrer alterações significativas com traumas ou injúrias, comuns nos tecidos bucais. Embora observadas com pequeno grau de expressão, essas variações, parecem ser progressivas, ou seja, mais expressivas com o uso continuado do medicamento. Mais estudos devem ser realizados, principalmente voltados para avaliações histoquímicas, bioquímicas e moleculares, no entanto nosso estudo é um alerta inicial para a avaliação dos tecidos bucais de pacientes que utilizam inibidores de protease. / HAART had a dramatic impact on the HIV infection, however, protease inhibitor exhibit significant drug-drug interactions, and side effects. There are only few data on effects of protease inhibitors on oral tissues. We propose to observe experimental effects of ritonavir on oral epithelial tissues, covering and glandular. Wistar rats received Ritonavir twice a week for 4-8 weeks. Controls received no treatment. At the time for sacrifice, plasma were collected for evaluation of triglycerides, total cholesterol, HDL, LDL and VLDL. Were also collected skin, tongue, palate and glandular tissues Lipoproteins were evaluated and histological examination of skin, mucosal epithelium on tongue, palate and salivar submandibular glandula were made under light microscope. Morphometric methods (cariometry and stereology) were used. Data were statistically analysed by Kruskal Wallis test for multiple samples, since our data were considered not-normal. P[U] 0.05 were considered statistically significant. Our results show that protease inhibitor may be associated with small alterations in epithelial tissues, significant mostly when on longer times using the medication. The complete significance of this data has to be better understood, and other studies has to be done to define these points.
113

Etude expérimentale de l'effondrement d'une colonne fluide-grains / Experimental study of the granular-fluid column collapse

Bougouin, Alexis 20 December 2017 (has links)
Autour de nous, les systèmes granulaires sont omniprésents et rarement dissociés d'une phase liquide ou gazeuse. L'interaction entre les deux phases (solide et fluide) implique une dynamique d'écoulement complexe de ces systèmes couplés. Cette thèse expérimentale a pour but de caractériser la dynamique d'effondrement gravitaire instationnaire d'une colonne fluide-grains dans différentes configurations de mélange diphasique. Considérant uniquement l'effet des grains au sein du fluide, la dynamique d'écoulement d'une suspension isodense dans l'air est d'abord abordée avec une description macroscopique. En particulier, La rhéologie du fluide apparent est extraite à partir de l'évolution temporelle du front en utilisant des solutions auto-similaires, modèles de la dynamique de propagation aux temps longs. Sur la gamme du nombre de Reynolds étudiée, la dynamique d'écoulement de la suspension est décrite comme celle d'un fluide apparent Newtonien ou non-Newtonien (rhéofluidifiant, rhéoépaississant, viscoplastique) dépendant des paramètres considérés (fraction volumique, viscosité du fluide interstitiel, diamètre des grains, protocole de préparation). Afin de décrire la configuration opposée d'un massif sédimentaire pour lequel les interactions entre particules solides deviennent dominantes, la configuration d'une colonne granulaire dense saturée en fluide, i.e. où les grains sont plus lourds que le fluide porteur, est ensuite étudiée. Un travail préliminaire est consacré à la caractérisation de l'effondrement d'une colonne granulaire totalement immergée dans un fluide. Le rôle dissipatif de ce dernier sur le milieu granulaire est mis en évidence par une analyse de la dynamique d'effondrement et des caractéristiques du dépôt final. Cette caractérisation permet de classifier les régimes d'effondrement en fonction de la viscosité et de la masse volumique du fluide environnant, i.e. du nombre de Stokes et du rapport de masse volumique entre le fluide et les grains. Dans le cas triphasique, i.e. lorsque la colonne fluide-grains s'effondre dans l'air, la dynamique peut être fortement affectée par les effets capillaires à travers le nombre de Bond qui contrôle alors la mise en mouvement de la colonne initiale. Quand ces effets deviennent négligeables à l'échelle de la colonne et à celle du grain, le fluide interstitiel peut jouer un rôle moteur ou dissipatif vis-à-vis dumilieu granulaire conduisant à une longueur d'étalement plus ou moins importante en comparaison au cas sec. Le rôle du fluide interstitiel dépend essentiellement de sa viscosité modifiant, par la même occasion, la dynamique d'effondrement. Enfin, une étude préliminaire sur la dynamique d'écoulement d'une suspension non-isodense, initialement homogène, est réalisée. Cette configuration, à la transition des situations décrites précédemment, permet d'aborder le couplage de la dynamique de sédimentation des grains et celle du courant. En particulier, nous observons que la vitesse de sédimentation décroît avec l'augmentation de la fraction volumiqueinitiale en particules. / On the Earth's surface, granular medias are ubiquitous and they are rarely dissociated from a liquid or a gas. The fluid-solid interaction leads to a complex flow dynamics of these coupled systems. This experimental work aims at characterizing the dynamics of the unsteady gravitydrivencollapse of a granular-fluid column within different configurations of the diphasic mixture. First, the flow dynamics of a neutrally buoyant suspension in air are characterized based on a macroscopic description of the flow. In particular, the rheological parameters of the apparent fluid have been extracted using the temporal evolution of the propagating front and self-similar solutions, models of the propagating dynamics at long times. In the considered range of the Reynolds number, the flow dynamics are described as an apparent Newtonian or non-Newtonian (shear-thinning/-thickening, viscoplastic) fluid depending on the various parameters (volume fraction, viscosity of the interstitial fluid, particle diameter, mixing protocol). In order to describe the opposite case of a sedimentary environment where particle-particle interaction becomes dominant, a second part of this work investigates the case of a fluid-saturated granular collapse, i.e. for which particles are heavier than the carrier fluid, in a dense packing configuration. For this purpose, a first part of the study is dedicated to characterize the collapse of an immersed granular column. The dissipative role of the fluid on the granular media is highlighted by an analysis of the collapse dynamics and the characteristics of the final deposit. This characterization allows to classify the regimes of the collapse depending on the viscosity and the density of the surrounding fluid, i.e. the Stokes number and the fluid-grain density ratio. In the triphasic case, i.e. when the granular-fluid column collapses in air, the dynamics may be strongly affected by capillary effects through the Bond number which controls the initial dynamics of the column. When these effects can be neglected (large Bond number) at the column and grain scales, the interstitial fluid can have a driven or a dissipative role on the granular media leading to a runout length more or less extended in comparison to the dry case. The role of the interstitial fluid depends mainly on its viscosity which also modifies the collapse dynamics. Finally, a preliminary study is realized on the flow dynamics of an initially homogeneous negative buoyant suspension column. This case, which makes the transition between the above mentioned configurations, allows to study the coupling between the settling dynamics of particles and this of the current. In particular, we observe that the settling velocity decreases with the increase of the initial volume fraction of particles.
114

Analyse expérimentale des paliers et des butées aérodynamiques à feuilles / Experimental analysis of aerodynamic foil journal and foil thrust bearings

Balducchi, Franck 12 December 2013 (has links)
Ce document présente les analyses expérimentales de deux types de composants aérodynamiques, lubrifiés en air : les butées à feuilles et les paliers à feuilles. Ces éléments constituent une nouvelle génération d'organes de guidages, et gagnent à être implémentés dans des machines tournantes dont les performances sont critiques. En effet, ils permettent d'atteindre des vitesses élevées, sans usure en régime établit, et diminuent la puissance dissipée en comparaison à des solutions fonctionnant avec de l'huile. Ce mémoire est une contribution à l'étude de chacun de ces éléments, dont les niveaux respectifs de maturité technologique ne sont pas similaires. Le palier à feuilles possède une littérature plus riche que la butée, dont aucune analyse expérimentale dynamique n'a été menée jusqu'à présent. Un banc d'essai, destiné à l'étude de butées à feuilles, sous des charges statiques et dynamiques, est conçu. Les caractéristiques de démarrage montrent une augmentation linéaire du couple de démarrage avec la charge statique, une augmentation linéaire du couple en fonctionnement aussi bien avec la charge statique qu'avec la vitesse de rotation, et enfin, une augmentation globale de la vitesse de décollage avec la charge statique. Les essais dynamiques montrent, pour la raideur dynamique, une augmentation non linéaire avec la fréquence d'excitation (entre 150 Hz et 750 Hz) ainsi qu'avec la charge statique appliquée. L'amortissement visqueux équivalent diminue avec la fréquence d'excitation, mais augmente avec la charge statique. Les essais montrent, à charge équivalente, une diminution de la raideur et de l'amortissement avec l'augmentation de la vitesse de rotation. Les facteurs d'amortissements structurels diminuent avec l'augmentation de la fréquence d'excitation, et augmentent avec la charge statique. Afin de se rapprocher d'une architecture de turbomachine, un banc d'essai existant est adapté à l'utilisation de paliers à feuilles. L'étude du comportement de deux rotors rigides (un léger et un lourd) est menée. Celle-ci s'effectue de deux façons : par l'analyse de spectrogrammes enregistrés suivant deux directions du plan de chaque palier, ou bien en étudiant la réponse synchrone à différents balourds. Une confrontation avec deux modèles théoriques est effectuée, en comparant soit la réponse synchrone au balourd dans chaque palier, soit les spectrogrammes. Les balourds sont comparés avec un modèle de rotor rigide linéaire (analyse en petites perturbations) à 4 degrés de libertés, dans lequel les coefficients dynamiques des paliers obtenus grâce au code Foil sont utilisés. les spectrogrammes montrent des vibrations sous-synchrones, qui sont reproduites dans ce mémoire au moyen d'un modèle simplifié de force dynamique. Les résultats expérimentaux actuels montrent les limites des modélisations des paliers à feuilles existantes. Afin d'améliorer la connaissance et la prédiction de ces composants, il est dorénavant nécessaire d'établir un nouveau modèle dynamique, non linéaire, permettant de prédire les réponses synchrones aux balourds ainsi que la richesse sous-synchrone de la signature dynamique d'un rotor supporté par ces paliers. / This document deals with the experimental analyses of two types of air lubricated aerodynamic components: foil journal bearings and foil thrust bearings. These components belong to a new generation of bearings, and are well worth integrating in turbomachinery, which performances are at stakes. Indeed they enable to reach very high speeds without any wear in continuous regime and they diminish energy loss compared to oil bearings. This memoir is a contribution to these two elements, which maturity levels are different.A test rig dedicated to the study of foil thrust bearings under both static and dynamic loads is designed. Start-up characteristics show a linear increase of start-up torque with static load, a linear increase of the fluid film torque with both static load and rotation speed, and an increase of lift-off speed with rotation speed. Dynamical tests show a non linear increase of the stiffness with both excitation frequency (between 150 Hz and 750 Hz) and static load. Equivalent viscous damping decreases with excitation frequency, but increase with static load. Loss factor decreases with excitation frequency and increase with static load.An existing test rig was modified to test foil journal bearings, in a close architecture compared to turbomachines. Two rigid rotors (one light and one heavy) supported by two foil journal bearings were studied. Study is made in two different ways: by the analysis of the displacements spectrograms in two perpendicular directions on each bearing, or the study of the synchronous response at different unbalance masses. A comparison between experimental results and two theoretical models is made. Unbalance responses are compared to a linear rigid rotor model with 4 degrees of freedom, in which the dynamic coefficients of the foil journal bearings are obtained thanks to the Foil algorithm. Spectrograms show sub-synchronous vibrations that are computed thanks to a simplified dynamic force model. Experimental results show the limits in the foil journal bearings theoretical models. In order to improve knowledge and prediction of these components, it is now compulsory to establish a new non-linear dynamical model, enabling to predict both the synchronous unbalance responses and the complexity of the sub-synchronous dynamical signature of a rotor maintained by two foil journal bearings.
115

The responses of ectohydric and endohydric mosses under ambient and enhanced ultraviolet radiation

Lappalainen, N. (Niina) 08 June 2010 (has links)
Abstract Previous reports on the effects of enhanced UV-B radiation on bryophytes have been equivocal. This study shows that mosses not only respond to enhanced UV-B, but they are affected by changes in ambient radiation. The studies were conducted with two model species common in northern environments; red-stemmed feather moss (Pleurozium schreberi) and juniper haircap moss (Polytrichum juniperinum). Both species showed high concentrations of methanol-extractable UV-absorbing compounds (UACs) with high spring-time and early-summer UV, whereas in P. juniperinum, the concentration was affected by early-summer drought. The UACs of P. juniperinum increased again towards autumn suggesting a role in winter hardening. The (spring-time) cell wall-bound UV screen was important to both species. The fundamental adaptation of P. juniperinum to open and exposed environments was reflected in relatively higher concentrations of total UACs compared to P. schreberi. The enhanced UV-B experiments in situ were conducted over two years in Oulu and six years at the FUVIRC site in Sodankylä. Some of the effects of UV-B were seen within the first years of the experiments, or even within hours, while others were observed after several years. Five or six years of enhanced UV-B treatment increased the methanol-extractable UACs of P. schreberi and decreased the green shoot growth of P. juniperinum. The immediate light environment was proposed to have an impact on the varying UAC concentrations. Some mitigating effects of UV-A were observed as well. Off-site measured, reconstructed and modelled UV radiation data was used for comparisons of light environment in situ, or when performing a reconstructive research with historical samples. The environmental sample banks can provide a useful tool to study past environmental conditions, and even reconstruct past radiation levels. It was shown in this study that UACs in P. schreberi and P. juniperinum have fundamental roles as UV-B screens in the cell walls, but there is also a variable response with the soluble fraction that reacts and adapts to the changes in UV radiation. The responses to increasing UV-B radiation vary in magnitude and in time. As P. schreberi and P. juniperinum possess circumboreal and cosmopolitan distributions, the effects of UV-B on these species and consequently on ecosystems has a broad application.
116

Heat transfer characteristics of natural convection within an enclosure using liquid cooling system

Gdhaidh, Farouq Ali S. January 2015 (has links)
In this investigation, a single phase fluid is used to study the coupling between natural convection heat transfer within an enclosure and forced convection through computer covering case to cool the electronic chip. Two working fluids are used (water and air) within a rectangular enclosure and the air flow through the computer case is created by an exhaust fan installed at the back of the computer case. The optimum enclosure size configuration that keeps a maximum temperature of the heat source at a safe temperature level (85°C) is determined. The cooling system is tested for varying values of applied power in the range of 15-40W. The study is based on both numerical models and experimental observations. The numerical work was developed using the commercial software (ANSYS-Icepak) to simulate the flow and temperature fields for the desktop computer and the cooling system. The numerical simulation has the same physical geometry as those used in the experimental investigations. The experimental work was aimed to gather the details for temperature field and use them in the validation of the numerical prediction. The results showed that, the cavity size variations influence both the heat transfer process and the maximum temperature. Furthermore, the experimental results ii compared favourably with those obtained numerically, where the maximum deviation in terms of the maximum system temperature, is within 3.5%. Moreover, it is seen that using water as the working fluid within the enclosure is capable of keeping the maximum temperature under 77°C for a heat source of 40W, which is below the recommended electronic chips temperature of not exceeding 85°C. As a result, the noise and vibration level is reduced. In addition, the proposed cooling system saved about 65% of the CPU fan power.
117

Origine des fractionnements isotopiques de l'azote et des gaz rares dans les météorites et les atmosphères planétaires / Origin of isotopic fractionations of nitrogen and noble gases in meteorites and planetary atmospheres

Kuga, Maïa 27 June 2014 (has links)
L’azote et les gaz rares présents dans les astéroïdes, les comètes et les atmosphères planétaires sont piégés dans de la matière organique et ont des compositions chimiques qui sont différentes de celle du Soleil, représentatif du gaz primordial à partir duquel les différents objets du système solaire se sont formés il y a 4,5 milliards d’années. Au cours de cette thèse, des synthèses de matière carbonée à partir d’un mélange de gaz ont été réalisées dans un plasma appelé le Nébulotron, afin de mieux comprendre les processus à l’origine des compositions de l’azote et des gaz rares présents dans les météorites. Les caractéristiques de la matière organique ainsi que la composition des gaz rares piégés dans les météorites sont relativement bien reproduites dans les expériences, mais pas celle de l’azote. Ces résultats expérimentaux permettent de proposer des mécanismes clé à l’origine des compositions des éléments volatils présents dans les objets du système solaire. / Nitrogen and noble gases present in asteroids, comets or planetary atmospheres are trapped in organic matter and bear a composition that is different from the composition of the Sun, which is representative of the primordial gas from which the different objects in the solar system were formed 4.5 billion years ago. During this thesis, experimental syntheses of organic matter from gas mixtures in a plasma setup called the Nebulotron were performed in order to better understand the processes responsible for this chemical difference between the meteorites and the Sun for nitrogen and noble gases. The characteristics of the organic matter and the signature of the noble gases trapped in meteorites are relatively well reproduced in the experiments, whereas the composition of nitrogen is not. These experimental results give hints about the key mechanisms that are responsible for the variations of the volatile elements composition in the solar system objects.
118

Contribution à l'analyse systémique, à la modélisation de la production et du déplacement des poussières lors de la démolition par foudroyage / Contribution to the systematic analysis, modeling of production and movement of dust during demolition by caving

Andlauer, Arnaud 02 February 2012 (has links)
La démolition de bâtiments par foudroyage est une technique devenue classique. Elle génère des nuisances qui doivent être prises en compte, sous peine de rendre caduc ce type d'activité. Les principales nuisances générées par le foudroyage sont : - les projections générées par l’explosion et la dislocation du bâtiment ; - l’onde de surpression générée par l’explosif ; - la vibration du sol induite par l’effondrement du bâtiment ; - la création et la propagation d’un nuage de poussière. Les deux premiers points sont maitrisés. En ce qui concerne les vibrations, aucune méthode n’existe pour les limiter. Seuls, des fossés creusés permettent de bénéficier d’un effet d’ombre vis-à-vis de certains bâtiments. Les nuisances générées par les poussières et les manières de les limiter commencent à être une question fréquemment posée. Dans le cadre de la destruction d’installation classée pour la protection de l’environnement, cette question devient critique, car ce nuage peut déplacer des particules nocives. Actuellement, aucune information sur les mécanismes de production ou sur les mécanismes de propagation des poussières n’a été élaborée. Cette thèse propose un protocole de mesure pour l'étude des caractéristiques du nuage de particule. Elle présente les premières informations sur la production et la propagation des particules. Et pour finir, elle présente les premières simulations numériques du phénomène. / The demolition of buildings caving is a technique which has become classic. The demolition generates nuisance that must be taken into account, under penalty of rendering this type of demolition. The main nuisance generated by the caving are: - The projections generated by the explosion and the disintegration of the building; - The pressure wave generated by the explosive; - The ground vibration induced by the collapse of the building; - The creation and spread of a cloud of dust. The first two points are controlled. With regard to vibration, no method exists to limit them. Only the ditches can provide access to a shadow effect vis-à-vis some buildings. Nuisances generated by dust and ways to limit them begin to be a common question. As part of the destruction of classified installations for environmental protection, this issue becomes critical because the cloud can move harmful particles. Currently, no information on the mechanisms of production or on the mechanisms of spread of dust has been developed. This thesis proposes a measurement protocol for the study of the characteristics of cloud particles. It prensetes the first information on the production and propagation of the particles. And finally presents the first numerical simulation of the phenomenon.
119

EOPEBEC - Etude et optimisation des performances énergétiques d’une enveloppe en béton de chanvre pour le bâtiment / Study and optimization of energy performance of a hemp concrete building envelope

Costantine, Georges 19 October 2018 (has links)
Dans un contexte de réchauffement climatique et de fin programmée des énergies fossiles, le secteur du bâtiment vise à réduire de 38% sa consommation d’énergie et à atteindre 10% de matériaux bio-sourcés utilisés dans la construction à l’horizon 2020. Ainsi, le béton de chanvre peut jouer un rôle majeur grâce à son bilan environnemental et à ses propriétés hygrothermiques qui lui permettent d’assurer un rôle d’amortisseur thermique et de stabilisateur de confort. Or le comportement hygrothermique du béton de chanvre à l’échelle du bâtiment est peu abordé dans la littérature et jamais pour les bâtiments tertiaires. L’objectif principal de ce projet est de combler ce vide en étudiant et en optimisant les performances énergétiques d’un bâtiment en béton de chanvre destiné à usage de bureaux et/ou de salles d’enseignement. Afin d’assurer le confort thermique intérieur différentes solutions techniques seront couplées au bâtiment et comparées entre elles : - une ventilation double flux thermodynamique associant une pompe à chaleur à une centrale double flux. - Une ventilation simple flux associé à un puits canadien qui récupère la chaleur du sous-sol pour préchauffer l’air de ventilation en hiver ou le rafraîchir en été. - Une ventilation double flux associé à un puits canadien. Par le biais de la simulation numérique et de mesures faites d’abord à l’échelle des composants, il sera ainsi possible d’évaluer le potentiel de chaque composant sur l’énergétique et le confort hygrothermique de bâtiments tertiaires intégrant principalement le périmètre du projet Grand Campus de Reims mais également pouvant être élargi à la spécificité d’autres climats français. / In a context of global warming and planned end of fossil fuels, the construction industry aims to reduce by 38% its energy consumption and to achieve 10% of bio-based materials used in construction in 2020. Thus, the hemp concrete can play a major role thanks to its positive environmental impact and its hygrothermal properties that allow it to ensure a role of heat damper and comfort stabilizer. Or hygrothermal behavior of hemp concrete throughout the building is little discussed in the literature and never for commercial buildings. The main objective of this project is to fill this gap by studying and optimizing the energy performance of a hemp concrete building designed for offices and / or classrooms. To ensure inside thermal comfort, different technical solutions will be coupled to the building and compared with each other: - A double flow thermodynamical ventilation combining a heat pump with a double flow central. - A simple flow ventilation associated to a pipe system which recovers heat from the basement to preheat ventilation air in winter and cool in the summer. - A double flow ventilation associated to a Canadian well. Through computer simulation and measurements made initially at the level of components, it will be possible to evaluate the potential of each component on the energy and hygrothermal comfort of commercial buildings mainly integrating the project boundary Grand Campus Reims but also can be extended to other French specificity climates.
120

Teplotní pole v tuhém palivu / Temperature field in solid fuel

Ptáček, Pavel January 2020 (has links)
The diploma thesis deals with a temperature field in a solid fuel during the combustion process. At the beginning of this thesis, research of available literature was conducted to obtain information about the composition of wood, properties affecting the combustion process, and the basics of heat transfer. Afterward, the temperature profiles of the samples were recorded during the measurement in the observation furnace. The temperature profiles of samples of six different sizes which were made of spruce and beech wood were subsequently evaluated and compared. Based on experimentally obtained data, a mathematical model was created in the OpenModellica software. Finally, the results of the mathematical model were compared with experimentally obtained data and appropriate conclusions were deduced.

Page generated in 0.0374 seconds