Teses / dissertações sobre o tema "Fourmis – Effets de la température"
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Gouttefarde, Rémi. "Aspects fonctionnels et morphogenèse des nids de termites et de fourmis : effets de la température et de l'humidité". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30357/document.
Texto completo da fonteFor many social insects, the nest is a central element for the colony's survival. A presumed function of the nest is to ensure protection against climatic fluctuations of the environment. One has to ask how the nests achieve to regulate such abiotic factors, and whether this factors modulate the construction behavior and thus the architecture of the nests. For all these questions only partial and fragmentary answers exist in the literature. The first aim of this thesis was to investigate the putative thermo regulating property of termite nests. We focused on two termite species found in the Brazilian cerrado: Cornitermes cumulans and Procornitermes araujoi. These two sympatric species both build nests consisting of an hypogeous and of an epigeous part. If these structures might seem similar, the internal architecture and the nest composition are quite different. We first aim to investigate whether these differences between the two structures influence their thermo regulating property. To do so, we monitored the temperatures inside the nests of the two species and we proposed a methodology to study the heat diffusion dynamics inside the structures. We also monitored the relative humidity, a factor that is essential for termite survival but that proved to be more complicated to understand. To complement this field work, we tested the survival of the two termite species in different conditions of temperature and relative humidity to test whether they present some adaptations to resist to such conditions related to their living environment. The second aim of this thesis was to study the effects of abiotic factors and more precisely temperature on the nest construction process. In fact, abiotic factors are known to affect insects' behavior, as much on the individual than on the collective level. Here we used the ant Lasius niger in which the construction behavior had already have modelled. This really common species of the northern hemisphere build a nest also made of an hypogeous and of an epigeous part. In the lab, the workers quickly build pillars that they covered by caps and thereby established the first basis of the structure. We performed an experiment where we constrained ants to build under different temperature conditions to test the effect of this abiotic factor on the emerging architecture. It is then possible to establish a quantitative and qualitative description of the architecture by scanning the structure thanks to a surface scanner or with X-ray tomography. Before studying the construction behavior, we first did an experiment to study the ants thermal preferendum. We found temperature regulation in the nest to follow the common heat equation where architecture only modifies the speed of heat diffusion in the nest. The studied environmental factors had complex effects on termite survival, ant distribution and the emerging ant architectures, the latter in agreement with the predictions of the construction model. However, we are still far from a coherent understanding of the interplay between the regulation of abiotic factors by the nest, their effect on his architecture architecture, and their influence on the animal's life history parameters
Challet, Mélanie. "Influence de la température et des courants d'air sur la morphogénèse des cimetières chez la fourmi Messor sancta". Toulouse 3, 2005. http://www.theses.fr/2005TOU30077.
Texto completo da fonteIn this work, we studied environmental effects on corpses aggregation in the ants Messor sancta. We characterized this phenomenon at both scales : individual and collective one. Results sew that ants have a lower dispersion on corpses piles. Ants sew a thigmotactic behavior around the piles. Our study also sew that pick up and drop behaviors are modulated by temperature. At the collective scale, we have shown that temperature and air flow modified collective aggregation dynamics. This modulation is the results of a complex coupling between individual sensitivity to local corpses density and individual sensitivity to climatic environment
Ponthieu, Raphaël. "Les fourmis et les machines : interfacer systèmes vivants et systèmes artificiels". Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC072/document.
Texto completo da fonteWithin the animal kingdom social insects fascinate humans. Especially ants, which are capable of adapting to various environments and taking advantage of their biotopes. Observing practices that we would have thought to be exclusive to humans – such as farming (of mushrooms) or breeding (of aphids) – spurs the will to understand by which mean ants operate. It turns out that ants achieve certain tasks in different ways than humans. For instance, to find the shortest path to a food source, or the best nest to migrate to; the colony can make a collective decision, decentralized and without the need of direct comparisons by individuals. My work has consisted of the elaboration and use of new methods to study ants. Two complementary objectives have been chosen to drive the work: implementation of a biohybrid system and assessing the means of and limits to controlling the behaviour of ants. The first objective consists of asking ourselves what will happen if we connected an ant colony with a computer For this I have designed apparatus that permit interaction between those two entities. It involved giving sight to the computer into what the colony was doing, then providing ways for the computer to act on the colony. To do so, I designed and tried out tools to monitor the activity of colonies as well as modular environments which ants can inhabit. I designed an embedded system that records and analyses activity of ant colonies on a micro-computer. I designed and 3D printed modules of various sizes that can be assembled together to form a structurally varied environment. For the computer to be able to act upon ant behaviour, I chose to endow it with the capability of modifying environmental conditions, at particular temperatures. Once the system was built, I conducted experiments to assess how local changes of temperature affect ant behaviour. This characterisation of behaviour under temperature changes sheds light on the relation of ants with their environment. This permitted the exploration of questions of control of behaviour of ants by a machine. The use of temperature having proved its capacity to modulate the local occupancy density, I then have been able to show that it was possible to confine an ant in a set location. Finally, I implemented a closed feedback loop system, in which the temperature used to confine the ant is dependent on the ant activity in real time. This last experiment shed light on the complexity of the dynamic relation between ants and their environments and opened new perspectives for future investigations. During this research, many tools were developed. Functional prototypes of moduary environments have demonstrated the relevance of using 3D printers for the study of ants. The various tools for monitoring, recording and processing video data provide new and innovative experimental possibilities and can be used for other studies, especially over long periods of time. Temperature control devices have as well been designed using rapid prototyping tools, making them accessible, scalable and reproducible in an open source approach
Kataya, Zeinab. "Effets de température sur les nanoparticules de CoAg : structure et effets de ségrégation". Phd thesis, Université d'Orléans, 2013. http://tel.archives-ouvertes.fr/tel-01004367.
Texto completo da fonteMieusset, Roger. "Effets de la température sur les fonctions testiculaires et épididymaires". Paris 11, 1992. http://www.theses.fr/1992PA11T022.
Texto completo da fonteManel, Stéphanie. "Modélisation de la durée de développement pré-imaginal chez les poïkilothermes sous régime de températures variables". Lyon 1, 1995. http://www.theses.fr/1995LYO10277.
Texto completo da fonteSalas, Lopez Alex. "Effets de l’anthropisation sur la diversité fonctionnelle des fourmis et leur participation dans des processus écosystémiques". Thesis, Guyane, 2016. http://www.theses.fr/2016YANE0004/document.
Texto completo da fonteLand-use changes have deep consequences on species diversity, community structure and ecosystem functioning. Consequently, many works have tried to understand the effects of such changes on the diversity and functional properties of organisms. It has been demonstrated that species traits are oftenly more important than the identity of species per se in order to account understand the ecological roles of species. Besides, while the majority of assessments about land-use change effects on ecosystem functioning have focused on primary producers, the contribution of other organisms is essential to maintain the functioning and resilience of ecosystems.Ants are interesting organisms to track land-use changes due to their abundance, ubiquity and ecological dominance. Ants are present in most of terrestrial biomes and participate in several ecosystem processes through their consumption of food resources. They are also easy to sample and standard methods exist to provide accurate comparisons between studies. While a number of studies have demonstrated abrupt changes in ant species composition along environmental gradients, only a reduced number of such studies have tried to understand how ant community changes affect ecosystem processes. Moreover, the traits responsible for the stability of ant communities in response to land-use changes are little known. It is therefore necessary to develop a methodology that enables a proper identification of ant participation to different ecosystem processes and their contribution to ecosystems’ resistance and resilience.In this thesis I aim to bring some light about i) how land-use changes affect ant community structure? ii) what traits are responsible of the ecological success of a species or it’s extinction from a given environment? iii) how changes in the species or trait composition affect the participation intensity of ants in different ecosystem processes ?
Roussy, Laurent. "Étude du comportement des matériaux composites aux températures cryogéniques". Besançon, 1994. http://www.theses.fr/1994BESA2050.
Texto completo da fonteDaviller, Guillaume. "Etude numérique des effets de température dans les jets simples et coaxiaux". Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2010. http://tel.archives-ouvertes.fr/tel-00573368.
Texto completo da fonteJean-St-Laurent, Mathilde. "Effets des cycles extrêmes de température sur le comportement des matériaux composites". Master's thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/26398.
Texto completo da fonteThis master dissertation presents the effect of extreme temperature cycles on composite materials of carbon fiber and cyanate-ester resin made of five harness woven fabrics. Three laminates and one sandwich plate were studied. The evaluation of damage present in the laminates showed two different types of damage: vertical microcracks and debonding between the fibers and the matrix. Debonding is only visible on the edges of the laminates. As for the microcracks, they are present both on the edges and inside of the laminates, but in greater quantity on the edges. The damage inside the sandwich plate is present under two forms: vertical microcracks and delamination due to the presence of the adhesive. The effect of thermal cycling on the degradation of the mechanical properties of the laminates was also studied. The mechanical tests performed showed that properties influenced by the matrix behavior were altered by the presence of microcracks.
Ishiguro, Naoko. "L'influence du climat et des affluents sur l'oxygénation et la turbidité des lacs : le cas comparé du Léman, des lacs alpins et japonais". Limoges, 2004. http://www.theses.fr/2004LIMO2002.
Texto completo da fonteBouhanek, Karima. "Oxydation à haute température de superalliages monocristallins". Toulouse, INPT, 1997. http://www.theses.fr/1997INPT016G.
Texto completo da fonteMykytczuk, Nadia, Leo Leduc, Jack T. Trevors e Garry D. Ferroni. "Effets des facteurs environnementaux du drainage minier acide sur les membranes d'Acidithiobacillus ferrooxidans". Acfas-Sudbury, 2007. https://zone.biblio.laurentian.ca/dspace/handle/10219/96.
Texto completo da fonteGhasemzadeh, Hasan. "Couplages dans les géomatériaux multiphasiques : effets de la température et de la chimie". Phd thesis, Ecole des Ponts ParisTech, 2006. http://pastel.archives-ouvertes.fr/pastel-00002077.
Texto completo da fonteKoo, Min. "Effets de température dans les procédés de gravure plasma : Aspects fondamentaux et applications". Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00355029.
Texto completo da fonteHammouda, Tahar. "Mécanismes et cinétique de fusion partielle d'assemblages à Fluor-Phlogopite : modélisation, expérimentation et implications géochimiques". Orléans, 1995. http://www.theses.fr/1995ORLE2015.
Texto completo da fonteReyt, Françoise. "Influence de la température sur la liaison calcium-protéine". Bordeaux 2, 1997. http://www.theses.fr/1997BOR2P017.
Texto completo da fonteBaril, Eugénie. "Quantification de l'influence de l'environnement sur la formation et la thermo-résistance des spores bactériennes". Brest, 2011. http://www.theses.fr/2011BRES2047.
Texto completo da fonteThe aim of this PhD study was to quantify the influence of the sporulation environment (temperature, pH and aw) on the spore formation of Bacillus weihenstephanensis and B. Licheniformis and on their heat resistance. A two-step sporulation methodology was developed to study sporulation in environmental conditions close to growth boundaries. Sporulation boundaries (temperature, pH and aw) were observed inner growth boundaries. A primary model was proposed to quantify the influence of the environment on spore formation. A decrease in sporulation temperature and pH delayed the time to first spore per ml. The maximal spore heat resistance was observed for spores produced at temperature and pH close to the optimal growth values. A secondary model was then proposed and validated to estimate the spore heat resistance as function of the sporulation and heat treatment environments. Finally, this study allows defining control points in foodstuff to prevent spores in food products. A relationship between the influence of environmental temperature and pH on growth and sporulation was pointed out
Desserrey, Franck. "Comportement mécano-chimique du nickel vis à vis de l'oxygène à haute température : aspects expérimentaux et prévisionnels". Dijon, 2002. http://www.theses.fr/2002DIJOS057.
Texto completo da fonteDasriaux, Marion. "Evolutions microstructurales du PEEK au-dessus de sa température de transition vitreuse lors de maintiens sous pression et température". Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2012. https://theses.hal.science/docs/00/78/60/16/PDF/Manuscrit_Dasriaux_Marion.pdf.
Texto completo da fonteAt least one fraction of the amorphous phase of semi-crystalline polymers, confined by the crystalline lamellae, is in out-of-equilibrium state, so that "physical aging" or "secondary crystallization" features can be observed (e. G. , by calorimetry) even above the glass transition temperature. This issue has already been addressed in the literature in several semi-crystalline polymers at atmospheric pressure. But despite the well-known influence of pressure on molecular mobility, the pressure-sensitivity of these microstructure rearrangements has never been tackled. This study focuses on amorphous evolution occurring in highly pressurized Poly-Ether-Ether-Ketone (PEEK), in comparison with atmospheric pressure. The phenomenon is tracked by Differential Scanning Calorimetry (DSC). A significant influence of pressure is evidenced, pressure confining rearrangements within spatially limited domains. The stability and co-existence of reorganization processes upon successive annealings is also investigated. Finally, relationships between constrained and free amorphous phase rearrangements are discussed. The free fraction of the amorphous phase results relaxed after annealing at atmospheric pressure and stabilized into a denser state after high pressure annealing. All these results allow to discuss the phenomena involved in the microstructural evolution of PEEK: a "physical aging" or "secondary crystallization"
Le, Morvan Caroline. "Effets des températures extrêmes sur l'expression des défenses immunes chez la carpe (Cyprinus carpio) : corrélation avec la dynamique membranaire des leucocytes périphériques". Lyon 1, 1995. http://www.theses.fr/1995LYO10055.
Texto completo da fonteAddala, Farida. "Etude du comportement rhéologique des bitumes à moyenne et basse température". Lyon, INSA, 1989. http://www.theses.fr/1989ISAL0066.
Texto completo da fonteThis study, performed in the framework of a collaboration with the Compagnie française de Raffinage Total France, is part of a general study on the rheological behaviour of bitumen. More specifically, our contribution consists of the development of an experimental apparatus allowing mechanical behaviour study of the bituminous material at low and medium temperature. In a first part we present the state of the art in this domain from experimental as well as theoretical point of view. In the the second part we describe the developed apparatus for torsion-compression tests on hollow cylindrical sample and we analyse the experimental results we have obtain. Finally the third part deals with numerical computations by the finite element method of the tests described in the previous part as well as the penetration tests. Different non-linear viscoelastic models have been used for this purpose after calibration of their parameters according to the experimental results
Dardié, Jason. "Étude des effets des rayonnements sur les matériaux et systèmes électroniques". Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS001.
Texto completo da fonteTMI-Orion, a company specialising in systems for acquiring physical parameters (pressure, temperature, humidity, etc.) for harsh environments, wishes to diversify, particularly in the civilian nuclear markets or the new space. These two markets are subject to strong radiative stress. The company, which is at the origin of the thesis, wishes to develop its skills with regard to radiative stress in order to be able to propose applications in these sectors. This thesis was therefore conducted with the main objective of providing as much information as possible on radiative stress to TMI-Orion. We have therefore identified four areas of work to address this issue.In the context of this thesis, we began by describing the radiative environments encountered in the space and civilian nuclear fields. Then the mechanisms of radiation-matter interaction were defined. Finally, the effects of radiation on electronics have been given.The second area of work consists of a study of the degradation mechanisms of elementary electronic components (MOS and bipolar transistors) as a function of the temperature to which they are subjected during irradiation. The effect of low (up to 100 K) and high (up to 400 K) irradiation temperatures on the degradation of elementary components was studied. During this study we were also able to compare the degradation obtained between a cobalt-60 irradiation and an X-ray irradiation.The third area of work consists of a simulation study on shielding against radiative stress. As part of this work, we have developed two calculation codes on GEANT4. The first one allows to study the dose deposited by a cobalt-60 source for different shielding conditions. The second one allows to model the X-ray generator of the IES laboratory and gives its energy spectrum. The effect of different filters on the spectrum is also studied.The last axis of this thesis work consists of a complete reliability study on autonomous data loggers developed by TMI-Orion. One particular recorder, the PicoVACQ, is used as an example. The reliability of this recorder was calculated by an analytical method, studied using the feedback available within the company, measured against thermal stress and measured against radiative stress. Finally, the search for a microcontroller, a central component of a radiation-tolerant data acquisition system, was carried out. One microcontroller in particular appears to have good resistance to dose effect and will probably be used by the company in its future projects
Racinais, Sébastien. "Performance de courte durée en milieu tropical:Influence de la Température environnementale et du moment de la journée". Antilles-Guyane, 2004. http://www.theses.fr/2004AGUY0118.
Texto completo da fonteMuscular power display a significant diurnal increase in a neutral environment only and a 60-minute moderately warm exposure increases muscular power in the morning only when body temperatures are their lowest (Sudy 1). The fact that the passive warm-up effect body temperature can not be combined may be explained by their similar action on muscular contractile properties (study 2). These results point to the existence of a "ceiling" above which an increase in body temperature fails to improve muscular performance. Indeed,our results show that an extremely hot exposure fails to modify short term performance in a moderately warm and humid environment (study 3). Similary to tropical climate,a 30-minute leg immersion in a hot bath in neutral environment may blunt the diurnal variation in muscular power (study 4),whereas active warm-up increases muscular power both in the morning and in the evening(sTUDY 5)
Talby, Riad. "Mesure des fluctuations de température avec des thermocouples fins, par référence à un fil "froid"". Aix-Marseille 2, 1987. http://www.theses.fr/1987AIX22011.
Texto completo da fonteMenou, Abdellah. "Etude du comportement thermomécanique des bétons à haute température. : Approche multi échelles de l'endommagement thermique". Pau, 2004. https://tel.archives-ouvertes.fr/tel-00008986.
Texto completo da fonteThis research work deals within the framework of the study of durability when subjected ti hight temperature in case of fire. The aim of this study is to identify the elementary mechanisms leading the degradation of concretes at hight temperature. Adopted step consists to uncoupling the thermal damage, of mechanical origin (accompanied with deformations) and which takes place in the macrocospic and tiny scale, of the thermal damage of physical and chemical origin (not accompanied with deformations) and which is due mainly to the physical and chemical alterations in material. This approach is based on the exploitation of two different models ; the "Digital Concrete" microscopic model and the macroscopic damage deviatoric model MODEV, both implemented in the F. E. Software SYMPHONIE. Concurrently, an experimental study was achieved in order to feed and to validatez the "Digital Concrete" model. The evolution of mechanical characteristics of concrete was studied using multi-scale approach and three point bending tests were performed on five cementeous materials. Multi-scales approach of the model "Digital Concrete" allowed to find by simulation the experimental warmly behaviour. This approach allowed to put in evidence the existence of the micromechanical deformation and to propose an original approach allowing identification by simulation the laws concretes behaviour at hight temperatures. This approach was also applied successfully to explain the thermoapplication refractory concrete subjected to very hight temperatures was also realized
Raharison, Lucie Hortense. "Exercice maximal, métabolisme musculaire et évolution des températures cutanée et centrale chez les sujets ayant présenté un "syndrome d'hyperthermie d'effort" (HTE)". Aix-Marseille 2, 2001. http://www.theses.fr/2001AIX22093.
Texto completo da fonteLaunay, Jean-Claude. "Les adaptations croisées climatiques chez l’humain : caractérisation, mécanismes et risques thermophysiologiques". Lyon 1, 2008. http://www.theses.fr/2008LYO10062.
Texto completo da fonteIntercontinental travels, but also overseas deployment of troops may submit adapted persons to a given thermal strain to an opposite thermal strain, exposing them to unassessed thermophysiological risks. This problem encompassed the poorly researched concept of thermal cross-adaptation. Using sweating tests (Tdb=45 °C, RH=10 %, 90 min) and standard cold air tests (Tdb=1 °C, 120 min) in humans, before and after heat acclimatization (28 d in French Guyana) or cold acclimatization (55 d in Artic), we characterized heat/cold and cold/heat cross-adaptations. The thermophysiological mechanisms involved in their development were described in 24 subjects submitted to different thermal loads. The resulting thermophysiological risks were evaluated. A methodology for studying, characterizing and assessing the medical risks for other cross-adaptations is proposed in order to optimize the medical prevention
Dasriaux, Marion. "Evolutions microstructurales du PEEK au-dessus de sa température de transition vitreuse lors de maintiens sous pression et température". Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2012. http://tel.archives-ouvertes.fr/tel-00786016.
Texto completo da fonteMnif, Hassène. "Contribution à la modélisation des transistors bipolaires à hétérojonction Si/SiGe en température". Bordeaux 1, 2004. http://www.theses.fr/2004BOR12786.
Texto completo da fonteThe consideration of the temperature and in particular of he self-heating effect in Si/SiGe heterojunction bipolar transistors is a fundamental aspect to predict in a precise way these electric characteristics. The use of these components in microwaves applications exposes to various tempertaures and strong densities of current, accentuates enormously these effects. Consequently, a precie modelling of these phenomena is necessary. A dynamic model describing the self-heatinng, characterized by a rise in the junction temperature, is developed. An electric equivalence close to the analytical model, compatible with SPICE electric models type, is established. A specific test bench is used in order to evaluate the new model and to extracts its parameters. In a second part, the temperature dependence of the various compact model parameters is studied, in particular in the HICUM model
Daniel, Isabelle. "Aluminosilicates à haute pression et haute température : amorphes, verres, liquides et cristaux : étude par spectroscopie Raman". Lyon 1, 1995. http://www.theses.fr/1995LYO10279.
Texto completo da fonteCourtial, Yannick. "Etude du comportement mécanique à haute température de cermets WC-Co : Effets de la microstructure". Lyon, INSA, 1991. http://www.theses.fr/1991ISAL0071.
Texto completo da fonteCharacterization of mechanical properties of WC-(17,5-25 %) Co cemented carbide at high temperatures (600-1000°C) and particularly of their resistance to crack propagation cannot be done by using the laws of behaviour of fragile materials (elastic range) and on the basis of the only criterion of KIc overload breakage. At this level of temperature, the behaviour of these materials is indeed of elastoplastic type. We have therefore used the notion of R CURVE : curve of resistance to crack propagation. We have thus access to the values of stable growth start of crack, of propagation and to the differentiation of elastic and plastic phenomena. Comparison of the different methods (RICE,GARWOOD and SAKAI) which allow to obtain R curves led us to the following conclusions: the RICE method is the most suitable for WC-Co cermets; KIc RICE corresponds to the start of stable growth of cracks;definition of a criterion as a criterion of overload breakage at hight temperature. We have developed at the same time a DOUBLE TORSION device and have applied this measure to the case of cermets. It has been possible to observe a slow growth of under-critical defects at 600°C. The objective of all these measurements is to observe the influence of MICROSTRUCTURE and COBALT CONTENT on the high temperature mechanical properties of cermets developed by the CERAMETAL (Lux) company
Grenier, Benjamin. "Spectroscopie théorique : description des effets de la température sur les paramètres de résonance magnétique nucléaire". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0494/document.
Texto completo da fonte- Our objective is to define a theoretical methodology, which allows to simulate the Nuclear Magnetic Resonance (NMR) spectra taking into account the temperature effects, in order to propose a help to the interpretation of the more relevant experimental results.- To deal with the description of the temperature effects on the NMR parameters, we have studied azacalixarenes, which are cyclic oligomers of phenol units linked together by nitrogen bridges. These molecules have a calyx shape, hence their name azacalixarenes. By this cavity these molecules can capture different types of compounds and are used in the host-guest chemistry field.- A wide variety of substituents can be attached to these azacalixarenes. Experimentally, one can easily follow the structure variations effects, at the level of physicochemical properties by NMR.- For this reason, we first investigated the geometric description of azacalixarenes as a function of different substituents and different isomers using the Density Functional Theory, so without taking into account the temperature. - Then, we simulated the NMR parameters of these systems using the Density Functional Theory. This is to calculate the azacalixarenes NMR spectrum in the ground state.- FInally, by performing molecular dynamics simulations using Molecular Mechanics, we were able to take into account the temperature effects. We were able to simulate the NMR parameters of these systems taking now into account the effects of temperature
Castellano, Aloïs. "Étude des effets de la température sur les combustibles nucléaires par une approche ab initio". Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS062.
Texto completo da fonteTo ensure the security of nuclear electricity production, an understanding of the behavior of nuclear fuel materials is necessary. This work aims at making a contribution to the study of the effects of temperature on nuclear fuels, by using an ab initio approach through density functional theory and ab initio molecular dynamics (AIMD). To explicity take account of the temperature, a non-perturbative lattice dynamics method is formalised, allowing to study the evolution of phonons and thermodynamic properties with temperature. In order to reduce the important computational cost of AIMD, a machine-learning based sampling method is developped, which allows to accelerate the simulation of materials at finite temperature. Those different methods are applied to describe the stabilisation of uranium-molybdenum alloy at high temperature, as well as the lattice dynamics of uranium and plutonium dioxides
Grenier, Benjamin. "Spectroscopie théorique : description des effets de la température sur les paramètres de résonance magnétique nucléaire". Electronic Thesis or Diss., Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0494.
Texto completo da fonte- Our objective is to define a theoretical methodology, which allows to simulate the Nuclear Magnetic Resonance (NMR) spectra taking into account the temperature effects, in order to propose a help to the interpretation of the more relevant experimental results.- To deal with the description of the temperature effects on the NMR parameters, we have studied azacalixarenes, which are cyclic oligomers of phenol units linked together by nitrogen bridges. These molecules have a calyx shape, hence their name azacalixarenes. By this cavity these molecules can capture different types of compounds and are used in the host-guest chemistry field.- A wide variety of substituents can be attached to these azacalixarenes. Experimentally, one can easily follow the structure variations effects, at the level of physicochemical properties by NMR.- For this reason, we first investigated the geometric description of azacalixarenes as a function of different substituents and different isomers using the Density Functional Theory, so without taking into account the temperature. - Then, we simulated the NMR parameters of these systems using the Density Functional Theory. This is to calculate the azacalixarenes NMR spectrum in the ground state.- FInally, by performing molecular dynamics simulations using Molecular Mechanics, we were able to take into account the temperature effects. We were able to simulate the NMR parameters of these systems taking now into account the effects of temperature
Rosen, Michel. "Contribution à l'étude des effets du vent et d'un gradient de température sur l'efficacité des écrans acoustiques". Le Mans, 1986. http://www.theses.fr/1986LEMA1007.
Texto completo da fonteEl, Babili Mohammed. "Métabolisme branchial de la sphingomyéline et transport du sodium chez deux espèces euryhalines : Dicentrarchus labrax et Carcinus maenas : influence de la température et de la salinté". Lyon 1, 1997. http://www.theses.fr/1997LYO10339.
Texto completo da fontePierrot, André. "Contribution a l'étude des transferts de chaleur à haute température dans les milieux alvéolaires". Perpignan, 1987. http://www.theses.fr/1987PERP0032.
Texto completo da fonteTrégon, Bernard. "Evaluation et caractérisation d'une technologie d'assemblage MCM-L pour environnement haute pression forte température (120 MPa, 175°C)". Bordeaux 1, 2002. http://www.theses.fr/2002BOR12580.
Texto completo da fonteThe first part of this study is an analysis of electronics needs for severe environmental conditions, that is pressure/temperature combined stress, and so the different potentials applications domains, The second part establish a liste of degradation modes of assembly materials implied in prototypes manufacture. These protoypes are intend to word under 120Mpa of pressure and 175°C of température. Analytic modelisation of each degradation modes are listed; Then we designed and realised an environmental test bench to study our prototypes. The third part is a theoretical behavioural study of components parts under pressure/temperature combined stress. This study has been completed through an experimental analysis. Finally, the fourth part is an experimental analysis of complete prototypes manufactured for our study. This analysis deals about sturdiness of the electronic funcion, so as about the different assembly options degradations of each protoypes. This analysis has been completed with a simulation study using finite elements method
Neuville, Daniel R. "Propriétés thermodynamiques et rhéologiques des silicates fondus". Paris 7, 1992. http://www.theses.fr/1992PA077141.
Texto completo da fonteGrignon, Christophe. "Un modèle de thermique 2D appliqué aux structures hétérogènes creuses avec source intérieure mobile en régime fortement varié : le cas du tube d'arme en rafale". Poitiers, 1995. http://www.theses.fr/1995POIT2303.
Texto completo da fonteDjezzar, Karina. "Sur l'étirabilité et la biétirabilité de copolymères d'éthylène et d'alcool vinylique". Lille 1, 1995. http://www.theses.fr/1995LIL10087.
Texto completo da fonteBlanco, Éric. "Température et émissivité des matériaux sous choc : étude expérimentale par pyrométrie optique à travers un matériau fenêtre". Paris 10, 1997. http://www.theses.fr/1997PA100203.
Texto completo da fonteThe temperature is an important parameter to determine the equation of state of shock loaded materials. Indeed, to solve the hydrodynamics equations system (where this parameter does not appear explicitly), it is necessary ti use a complete equation of state connecting thermodynamics parameters : pressure, density, specific internal energy and temperature. In order to determine temperature along the isentropic release of studied material, a window material in lithium fluoride is used. Three different samples (bismuth, copper and tin) have been studied in a shock pressure range between 10 GPa and 100 GPa. We have designed and built a multispectral pyrometer having 8 measurement channels and operating in in a specral range between 0. 4 µm and 3. 5 µm. The pyrometer spectral range allows to uncouple the usually associated problems of studied material temperature and emissivity. The short wavelength measurement (visible range) allows to determine the true temperature of shocked material. Dynamic emissivity variation versus the wavelength is obtained in the infrared range and allows us to know the state changes undergo by the shocked material. The experimental results have allowed us to point out : - a temperature and emissivity increasing versus the shock pressure, - a state change (solid-liquid) for bismuth at shock pressure of 32 GPa
Adt, Isabelle. "Influence de facteurs environnementaux sur la physiologie et le métabolisme de SINORHIZOBIUM MELILOTI M5N1". Compiègne, 2002. http://www.theses.fr/2002COMP1421.
Texto completo da fonteSerdechnova, Maria. "Le contrôle de réactivité d'aluminium en peinture anticorrosion résistant à la haute température". Paris 6, 2012. http://www.theses.fr/2012PA066287.
Texto completo da fonteThe aim of this work is to understand Al reactivity at a fundamental level and to use this knowledge for the development of Cr(VI)-free sacrificial paints for high temperature aeronautic applications. Pure Al, Al intermetallics and alloys are studied. The atomic emission spectroelectrochemistry is used to isolate the individual phenomena during paint degradation. A linear relationship between cathodic current and Al dissolution is shown and interpreted with a simple model where OH- generation, Al(OH)3 formation/dissolution and Al(OH)4− diffusion are kinetically coupled. For early formulations significant binder dissolution is measured under cathodic polarization, while Al reactivity is suppressed. Similar Al behavior is observed for Al-Mg intermetallics. In terms of the cathodically generated hydroxide mechanism these results are interpreted as the reaction of either Si or Mg with OH-. These results confirm the cathodic Al reactivity model. The loss of anodic activity is explained by the loss of electrical contact at the metal/oxide/polymer/substrate interfaces and the oxide layer modifications are studied to circumvent this problem. It is found that Mg2+ ions retard Al passivation and improve conductivity due to the formation of semiconducting spinel. Finally, two major factors are found to be critical for the Al reactivity control: solution pH and oxide properties. Using additives to control them, the new coating formulation stable up to 550°C and protective more than 1000H in salt spray test is developed
Bobroff, Julien. "Etude par RMN des corrélations magnétiques dans les supraconducteurs à haute température critique: effets des impuretés". Phd thesis, Université Paris Sud - Paris XI, 1997. http://tel.archives-ouvertes.fr/tel-00001972.
Texto completo da fonteMailly, Sandrine. "Effets de la température et de l'environnement sur la résistance à la fatigue d'alliages de titane". Poitiers, 1999. http://www.theses.fr/1999POIT2262.
Texto completo da fonteMejia, Daniel. "Effets de la température de paroi sur la réponse de la flamme à des oscillations acoustiques". Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0026/document.
Texto completo da fonteCombustion instabilities, induced by the resonant coupling of acoustics and combustion occur in many practical systems such as domestic boilers, gas turbine and rocket engines. They produce pressure and heat release fluctuations that in some extreme cases can provoke mechanical failure or catastrophic damage. These phenomena have been extensively studied in the past, and the basic driving and coupling mechanisms have already been identified. However, it is well known that most systems behave differently at cold start and in the permanent regime and the coupling between the temperature of the solid material and combustion instabilities still remains unclear. The aim of this thesis is to study this mechanism. This work presents an experimental investigation of combustion instabilities for a laminar premixed flame stabilized on a slot burner with controlled wall temperature. For certain operating conditions, the system exhibits a combustion instability locked on the Helmholtz mode of the burner. It is shown that this instability can be controlled and even suppressed by changing solely the temperature of the burner rim. A linear stability analysis is used to identify the parameters playing a role in the resonant coupling and retrieves the features observed experimentally. Detailed experimental studies of the different elementary processes involved in the thermo-acoustic coupling are used to evaluate the sensitivity of these parameters to the wall temperature. Finally a theoretical model of unsteady heat transfer from the flame root to the burner-rim and detailed experimental measurements permit to establish the physical mechanism for the temperature dependance on the flame response
Biolchini, Romain. "Etudes des effets de température sur le bruit de jet subsonique par simulation des grandes échelles". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC064.
Texto completo da fonteIn this PhD thesis, the effects of temperature on aerodynamic development and acoustic radiation of subsonic jets are studied. This is done thanks to 3D compressible Large Eddy Simulations with low dissipative and dispersive numerical schemes that propagate the acoustic waves properly. The far-field noise is then determined with the acoustics analogy proposed by Ffowcs-Williams and Hawkings.First, single round jets are studied. Two operating points are computed: an isothermal jet and a hot jet with an exhaust temperature twice the one of the ambient air (Tj = 2T0). The comparison of both cases is based on a similar exhaust velocity. In both cases, Reynolds number based on the nozzle diameter is above 105. To validate numerical methodology, aerodynamic and acoustic results are successfully compared against experiments. Further analyses are conducted to highlight the new acoustic sources that result from the temperature increase and the effects on the azimuthal mode distribution.Secondly, a more complex geometry representative of a real turbofan engine is considered, including two streams and the plug. The same methodology as the one used for the single jet nozzle is applied. Again, two simulations are computed where the exhaust velocities of both streams are kept constant and only the exhaust primary stream temperature is modified (multiplied by two). Differences on aerodynamic development are less important than the ones observed on single stream jets. However, the upstream acoustic radiation is significantly influenced by the modification of the exhaust temperature. In the colder case, upstream acoustic trapped waves are evidenced in the core jet and interact with the plug. This phenomenon is not reproduced when the primary stream is heated and explains the observed differences on the acoustic radiation
Shi, Xiangjun. "Etude par simulations de dynamique des dislocations des effets d'irradiation sur la ferrite à haute température". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066500/document.
Texto completo da fonteThis study is a contribution to the multi-scale modeling of hardening and embrittlement of the vessel steel in Pressurized Water Reactors (PWR) under irradiation conditions. Dislocation Dynamics simulations (DD) were conducted to describe the plasticity of irradiated iron at grain scale. Quantitative information about the pinning strength of radiation-induced loops was extracted and can be transferred at crystal plasticity scale. Elementary interactions between an edge dislocation and different types of loops were first analyzed. A new model of DD was identified and validated, both qualitatively in terms of interaction mechanisms and quantitatively in terms of critical stress, using Molecular Dynamics results available in the literature. The influence of the size of the loops and of the strain rate was particularly studied. Elementary simulations involving a screw dislocation and the same radiation-induced defects were conducted and carefully compared to available MD results, extending the range of validity of our model. Finally, a set of massive simulations involving an edge dislocation and a large number of loops was performed and allowed a first estimation of the obstacle strength for this type of defects (α≈0.26). This value is in a good agreement with previous experimental and numerical studies, and gives us confidence in future work based on this new DD model