Dissertations / Theses on the topic 'Assemblages'
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Zerrouki, Djamal. "Assemblages colloÏdaux organisés." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://pastel.archives-ouvertes.fr/pastel-00003919.
Full textMlot, Nathaniel J. "Fire ant self-assemblages." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50247.
Full textSnape, S. R. "Mortuary assemblages from Abydos." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375851.
Full textOlive, Maxime. "Démontabilité des assemblages structuraux." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13705/document.
Full textThe INDAR process (INnovative Disassembling Adhesives Research), patented by RESCOLL, is a technological answer for the dismantling on command of structural bonded joints (easier recycling and maintenance). This process is based on the reformulation of primers or adhesives with specific chemical compounds. The works carried out enabled a better understanding of the debonding mechanism, in order to extend it to other configurations of adhesives and activation conditions (different temperature, heating method). The results obtained broadened the scope of possible applications for this technology (aeronautics, defence, automotive) and confirmed the strategical interest ot this topic
Mauroy, Chloé. "Fusion d'auto-assemblages lipidiques." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1039/.
Full textMembrane fusion processes play a key role in biological system. Fusion processes involve destabilization of membrane organization. This is a controlled phenomenon which is not spontaneous because of energetic barriers. To abolish these barriers, it is necessary to provide energy to the system. In a first part, electrofusion between two giant unilamellar vesicles (GUVs) was studied. The fusogenic state was obtained by the application of an exogenous electric field to induce membrane electropermeabilization. External electric field can induce membrane destabilization allowing fusion between these two membrane systems in contact during the electric pulse. We characterized, on the first hand, the role of phase states of the membrane and the critical electric field for electropermeabilization and, on the other hand, the morphological modifications associated to this homofusion. In a second part, spontaneous fusion between catanionic vesicles and GUVs with different compositions and phase states was studied. We underline the fact that the interactions between these two systems depend, on the first hand, on the phase states of the GUVs and, on the other hand, on the electrostatic interactions between them. Fusion is induced when the membrane is destabilized. This destabilization is induced here by the presence of an endogenous electric field revealed by the zeta potential of the catanionic vesicles
Palmer, Denise D. "Late Holocene planktic foraminiferal assemblages from Orca Basin : effects of dissolution on faunal assemblages." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001693.
Full textSchull, Guillaume. "Dynamique d'auto-assemblages moléculaires bidimensionnels." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2006. http://tel.archives-ouvertes.fr/tel-00143236.
Full textSchaeffer, Gaël. "Dynamères multiples et assemblages supramoléculaires." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00764047.
Full textBerry, Christopher Mark. "Devonian plant assemblages from Venezuela." Thesis, Cardiff University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492235.
Full textSellem, Eric. "Caractérisation probabiliste des assemblages hyperstatiques." Châtenay-Malabry, Ecole centrale de Paris, 2000. http://www.theses.fr/2000ECAP0903.
Full textEmmrich, Matthias. "Fish assemblages in European lakes." Doctoral thesis, Humboldt-Universität zu Berlin, Landwirtschaftlich-Gärtnerische Fakultät, 2013. http://dx.doi.org/10.18452/16681.
Full textLake fish assemblages are increasingly exposed to environmental change in their habitats. The investigation of abiotic and biotic factors and their effects on the size structure of lake fish is essential for predicting the response of fish assemblages to environmental change. However, sampling of lake fish is challenging because sampling gears are selective. The quality and correspondence of fish catches from angling, gillnetting, trawling and hydroacoustics were analysed. Non-standardised catch data from recreational angling were of limited quality for a comparison of fish stocks. Vertical hydroacoustics is an efficient method to quantify fish biomass in stratified lakes. Sampling effort of multi-mesh gillnets can be reduced when fish abundance estimates are derived from contemporarily operating hydroacoustics. Trawling is useful to sample pelagic fish assemblages in deep lakes. The size structures of fish assemblages differed on a small and a large geographical scale along gradients of abiotic and biotic lake descriptors and differences in fish assemblage composition. At a small geographical scale assemblages in deep and less nutrient-rich lakes with high predator abundances were characterised by a higher proportion of large fish. Shallow nutrient-rich lakes with few predators were characterised by more medium-sized fish. At a large geographical scale thermal optima of fish generated two types of assemblages with different size structures. A high proportion of large salmonids was observed in coldwater lakes at high elevation sites in northern and southern Europe. Lowland lakes with cool- and warmwater fish were dominated by small-sized individuals. The results suggest that lowland lake fish assemblages are relatively robust against environmental change. Coldwater fish assemblages instead may suffer dramatic consequences from global warming as expected species shifts are likely to be accompanied by shifts in the size structure towards smaller individuals.
Robert, Charlotte. "Fiabilité des assemblages de puissance." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLN001/document.
Full textThe reliability of electronic compound, especially in advanced technologies, is becoming very important. This is motivated by the volume reduction asked in highly loaded structures. Moreover, its required lifetime can be about decades. Here, we have an electronic substrate. A power electronic circuit lays on it. In such circuit, compounds like chip are heating up. This rising of temperature from the chip propagates on the substrate. Furthermore others environmental amplitudes of temperature will be imposed like the day/night cycle for satellites or the rock temperature in well bores. The substrate is composed of several ceramic layers with metal conducting tracks inside and in between. When theses materials dilate it induces stress concentrations and gradients. Since theses changes are occuring on important durations, they cans lead the substrate to a fatigue failure. The point of this study is to understand the failure mechanisms leading to break and the means to avoid them. Then we seek to determine simple conception rules such as the size and the gap between different tracks going through the ceramic. Thanks to the use of the fracture mechanics on the substrate and according to the previously described use, we will evaluate the critical failures. Thus, the mechanical modelling of the substrate will generate some rules for the dimensions
Burel, Céline. "Synthèses et assemblages de nanoparticules." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066207/document.
Full textNanoparticles (NPs) assembled into two- or three-dimensional architectures offer new collective optical, magnetic and electronic properties. For instance, closely packed gold (Au) and silver (Ag) NPs absorb light at higher wavelength than when they are far apart. In the first part of this thesis, the technique of microfluidic pervaporation is used to assemble micron size latex particles and Au NPs in bulky materials of controlled dimensions. By reducing the concentration of salts in the particles dispersions, the particles organize in hexagonal crystals. Millimeter-long materials of small well-organized densely packed particles are collected, offering solid groundwork as for the design of new functional microscale optomaterials. In the second part of this thesis, the assembly of NPs on droplets is used to fabricate dispersed materials. By tuning the charges and wettability of Au and Ag NPs, they adsorb at the surface of emulsion droplets. A subsequent polymerization at the interface of the emulsion allows to lock the NPs inside an organic shell. In well-defined conditions, novel Au NP-silica microcapsules responsive to mechanical strains and Au NP-polyacrylate microcapsules responsive to pH variations are engineered. These microcapsules change color during their deformation due to the increase of the distance between the Au NPs. Each one of the microcapsules being one sensor by itself, these results pave the way as for the design of new microscale sensors
Burel, Céline. "Synthèses et assemblages de nanoparticules." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066207.
Full textNanoparticles (NPs) assembled into two- or three-dimensional architectures offer new collective optical, magnetic and electronic properties. For instance, closely packed gold (Au) and silver (Ag) NPs absorb light at higher wavelength than when they are far apart. In the first part of this thesis, the technique of microfluidic pervaporation is used to assemble micron size latex particles and Au NPs in bulky materials of controlled dimensions. By reducing the concentration of salts in the particles dispersions, the particles organize in hexagonal crystals. Millimeter-long materials of small well-organized densely packed particles are collected, offering solid groundwork as for the design of new functional microscale optomaterials. In the second part of this thesis, the assembly of NPs on droplets is used to fabricate dispersed materials. By tuning the charges and wettability of Au and Ag NPs, they adsorb at the surface of emulsion droplets. A subsequent polymerization at the interface of the emulsion allows to lock the NPs inside an organic shell. In well-defined conditions, novel Au NP-silica microcapsules responsive to mechanical strains and Au NP-polyacrylate microcapsules responsive to pH variations are engineered. These microcapsules change color during their deformation due to the increase of the distance between the Au NPs. Each one of the microcapsules being one sensor by itself, these results pave the way as for the design of new microscale sensors
Paroissien, Eric. "Contribution aux assemblages hybrides (boulonnés/collés) - Application aux jonctions aéronautiques." Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00171103.
Full textRevillod, Guillaume. "Diffusion hyper Rayleigh des assemblages moléculaires." Phd thesis, Université Claude Bernard - Lyon I, 2006. http://tel.archives-ouvertes.fr/tel-00106415.
Full textconversion de deux photons à la fréquence fondamentale en un photon à la fréquence
harmonique, permet de sonder la matière à des échelles sub-longueur d'onde. Pour mettre en
évidence cette propriété, la technique de diffusion hyper Rayleigh a été employée pour sonder
l'organisation dans des assemblages moléculaires dispersés en solution liquide. Après une
étude initiale de quelques solvants usuels purs, l'influence de l'environnement sur la réponse
du cristal violet, une sonde moléculaire octupolaire de référence, a été étudiée. Ces études ont
été poursuivies pour des sondes moléculaires amphiphiles afin d'étudier des solutions mixtes
comprenant à la fois des sondes libres et des sondes engagées dans des assemblages
moléculaires appelés micelles. En raison de la centrosymétrie de ces assemblages, la
composante dipolaire de la réponse harmonique diffusée s'affaiblit, laissant la réponse
harmonique totale dominée par une forte contribution quadripolaire clairement mise en
évidence par ces mesures de diffusion hyper Rayleigh résolue en polarisation. Un modèle
complet décrivant les différentes composantes de la réponse harmonique totale est introduit
pour interpréter globalement les observations sur ces solutions mixtes. Enfin, les études
préliminaires d'un système biomimétique reconstitué à l'interface air-eau par doublage de
fréquence sont présentées.
Nyonator, John Paul. "Informal Knowledge and Biomedicine: Ghanaian Assemblages." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28666.
Full textBoyd, Sheree. "Benthic invertebrate assemblages and sediment characteristics." Click here to access this resource online, 2009. http://hdl.handle.net/10292/727.
Full textInward, Daegan J. G. "The evolution of dung beetle assemblages." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405366.
Full textTrentin, Maria Giuseppina. "North-Western Uruk period pottery assemblages." Thesis, University College London (University of London), 1991. http://discovery.ucl.ac.uk/1361003/.
Full textRasmussen, J. "Multispecies effects in larval fish assemblages." Thesis, University of Aberdeen, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590944.
Full textFraser, Sally Elizabeth Mary. "The ecology of woodland parasitoid assemblages." Thesis, University of York, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428501.
Full textFinlay, John. "Picasso's constructions and assemblages : 1912-1935." Thesis, Courtauld Institute of Art (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312831.
Full textAntoni, Nicolas. "Phénomène de microreptation des assemblages mécaniques." Chambéry, 2005. http://www.theses.fr/2005CHAMS043.
Full textCumulative microslip is among the phenomena that have to be taken into account when one deals with the mechanical aspect of an assembly subjected to thermal or mechanical cyclic loading. The accumulation of relative infinitesimal slip in a preferred direction at the contact interface kinematically characterizes this phenomenon and recalls the Ratchetting effects in elasto- plasticity. Ln reality, it leads to significant global displacements of components relatively from each other. Consequently, it is accountable for the failure of some assembly parts of InternaI Combustion Engines and transmissions in the automotive industry. After examining real case situations and positioning our area of study, some properties related to the general attributes of the accumulation, particularly in the case of translation effects, have been established and illustrated with a reference example. Next we investigate the behaviour of some more realistic models in the presence of a dissymmetry which may be just as well of loading type, as geometric or tribological sort. Ln particular one has bought a highly special attention to the one of friction, from theoretical, experimental and numerical points of view, due to its non-classical nature. The existence of a dissymmetry in an assembly represents definitely a necessary condition for the phenomenon to occur. However this is not a sufficient condition and the additional characteristics required to reproduce it, such as initial contact, friction and loading conditions have been identified and systematically analyzed. Rotation effects have been found fairly often for the connecting rod big end associated with its bearing. From a physical analysis of the situation, a predictive criterion, based on the construction of charts and particularly on a straightforward experimental test, bas been proposed to the connecting rod designer
Ali, Mohamad. "Assemblages structuraux des convertisseurs de puissance." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT003H/document.
Full textIncreased performance of railway traction equipment, until now relied primarily on the integration of innovations in the field of electrical and dielectric materials, but the standardization of subassemblies reusable us to reconsider the structural assemblies of the traction cubicles (power converters). These cubicles are assembled now with mechanical fasteners (bolts, rivets), the first goal is to improve knowledge of the mechanical behaviour of these types of joints through an experimental study based on statics and dynamics tests of bolted and riveted joints. These tests have allowed us to validate numerical models of finite elements by using the computer codes ABAQUS® and ANSYS®. The second part of the thesis deals with the structural adhesive joints. We studied the possibility of replacing conventional mechanical assembly structural bonding. The first phase of our work was to identify and select structural adhesives that could meet our specifications. In this section the following work has been made: - Study of thermo-mechanical behaviour of the adhesive with the bulk Adhesive Test Specimens. - Statics and dynamics test in the bonded joint. - Non-linear 3D finite elements models. - Hygrothermal accelerated to study the effect of aging on the adhesive according to the humidity and temperature
Segovia-Brandt, César. "Performances des assemblages par tourillons soudés." Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10040/document.
Full textWood welding with dowel high speed rotation without any adhesives in wood furniture joints has a very important resistance. A wood joint is a method which makes it possible to maintain together two parts according to the consumer’s requirements (esthetic, mechanic resistance, life cycle) and the wood industry politic. This work is framed in the structural solid wood welding by mechanic friction to use in joineries, cabinet makings or constructions. We will show the feasibility of the welding joint design obtained with rotary friction using a traditional drill press and an automatic welding machine, which allows us to find furnishing’s industry applications.This process, which has been studied only for some years (2001), has been discovered in a polymer contribution study in the adhesion of solid wood. It can be carried out by linear alternative frictions or by rotation of a cylindrical part (called dowel) in a drilling of smaller diameter. In both case, the rise of temperature generated by frictions produces the fusion and the mixture of the lignocellulosic matter, which makes it possible for the two pieces to be welded without any matter contribution but only with the fibers’ tangle.The objective of this work is the parallel and perpendicular fibers joints, the most used in the furnishing design, through three kinds of assembly: bevel, half-lap and the groove and tongue joint. About the parallel fibers joints, we made the comparison between the ones welded, the ones nailed and the last ones gluing. For the type T perpendicular joints, comparison has only been made between the welding and those of gluing ones. For the type L perpendicular welding, the study was carried out according to the procedure CTBA L-161 (2000) of French Standard NF P 20-501. Finally, about the panels, we showed the laminated-welded without adhesive joints performance
Revillod, Guillaume Brevet Pierre-François. "Diffusion hyper Rayleigh des assemblages moléculaires." [s.l.] : [s.n.], 2006. http://tel.archives-ouvertes.fr/docs/00/10/64/15/PDF/These_G.Revillod.pdf.
Full textTo, Minh Nhat. "Mastic fonctionnalisé pour l’amélioration de la performance mécanique des assemblages boulonnés." Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0019.
Full textAssembly technique plays a crucial role in the formation of the structure and in transferring loads between components. This research project delves into the idea of bolted-sealed (BS) assembly technologies in the field of structural design, particularly focusing on improving the mechanical performance of bolted joints besides the capability of corrosion protection. On optimizing the strength-to-weight ratio of traditional bolted joints, our research offers a novel methodology to improve these connections through the development and application of functionalized elastomeric sealants.The primary aim of the study involves a comprehensive characterization and modeling of the mechanical fatigue behavior of elastomeric materials used in sealant layers and BS assemblies. Manipulating various simulation techniques from 1D analytical to 2D and 3D finite element methods, this work introduces a methodology to reduce the time and cost involved in experimental testing, while increasing the accuracy of mechanical behavior prediction. The study also aims to determine the appropriate level of modeling complexity, taking into account evolving computation capabilities. Particular attention will be given to simulating double-lap pure bonded and BS assemblies, expanding its application scope to elastomeric materials. Material identification is also a highlight in this research, including analytical and numerical approaches. The efficacy of these simulation methodologies will be validated by comparing simulation outcomes with experimental test results, using technical solutions such as stereo-correlation and infrared thermography.The second aspect of the research targets the formulation of a functionalized sealant, intended to necessarily enhance the fatigue life of bolted assemblies in aerospace applications. Key challenges include increasing mechanical resistance of silicon-carbide-reinforced sealant especially under cyclic loading, decreasing the load transferred by the bolt in BS configuration. The desired outcome is a significant fatigue improvement in BS assembly performance when the sealant layer remains undamaged. This investigation aims to provide a comprehensive understanding of elastomeric materials in BS joints, offering a scientific basis for novel sealant formulations and facilitating advancements in aerospace assembly technologies
Bergara, Tomas. "Réversibilité de l'adhérence dans des assemblages structuraux modèles." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14445.
Full textStructural adhesives are nowadays widely used in numerous industries like automotive, aerospace, avionics or microelectronics … for many reasons such as easy processing or weight and cost savings. A strong effort has been achieved so far to enhance the level of adherence in structural assemblies and in this particular case a new challenge appears: the easy dismantling of structural bonded joints. This innovative concept results from industrial constrains like maintenance or recycling needs.This work studies a process which offers a simple and efficient solution to the disassembling of structural bonds. Based on the use of specific additives activated by heating at a certain temperature, this new technology allows the drastic decrease of the bonding performance and allow the dismantling in a very short time. It fulfills the main characteristics required by this application, like no change in processing (implementation, curing conditions,…) and no or slight modification of the mechanical properties. The results of the influence of adding additive is evaluated.This process is based on the incorporation. of specific chemicals in the adhesive or primer formulations. These additives are selected according to specific properties like decomposition temperature. An innovative aspect of this technology lies in the localization of the dismantling. The first step of the additive action is migration from the bulk of the adhesive to the interface. In a second time, once at the interface, the decomposition gases generated by the additive (mainly steam and nitrogen) induce constrains and stresses. After a certain time, theses stresses are sufficient enough to overcome the adhesion forces and the adhesive debonds from the substrate, adhesive failure occurs. One logical consequence of this interfacial action is the use of a dismantling primer, which enables to improve the efficiency of the technology and allows additive savings.This work proposes mecanisms based on experimental results in order to explain what happens in the adhesive bulk and on the interfaces. Finally, an application of this process is described related to the use of debondable adhesive for structural coupling during ground tests in the frame of GAIA telescope. Its main structure is a multi segments brazed torus in silicon carbide. In order to test each segment, a structural and debondable epoxy adhesive was developed, allowing structural bonding at room temperature and easy dismantling with interfacial failure after thermal activation. After testing and dismantling, segments were reused for final application
McHenry, Patrick John. "Vanguard assemblages new media and the enthymeme /." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010505.
Full textWilkie, Alex. "User assemblages in design : an ethnographic study." Thesis, Goldsmiths College (University of London), 2010. http://research.gold.ac.uk/4710/.
Full textGonzaga, Ruth Goretti. "Garnet-clinopyroxene assemblages in the Earth's mantle." Thesis, Royal Holloway, University of London, 2007. http://repository.royalholloway.ac.uk/items/289f3b02-5a9c-4171-bee4-4e01e8e436bb/1/.
Full textPicardat, Emmanuelle. "Etudes d'auto-assemblages polydiacétylèniques et applications biologiques." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00855285.
Full textPincemaille, Justine. "Interactions et assemblages de prolamines du blé." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG056/document.
Full textThe aim of this thesis is to provide structural and functional knowledge on wheat gluten proteins. For that, we use the physical methods and the concept of soft matter. We optimize an extraction protocol based on a liquid-liquid phase separation. With this protocol, we obtain protein batches with different glutenin/gliadin mass ratios, which we then study in a 50/50 water/ethanol solvent (v/v). We show that proteins behave like polymer chains in θ solvent in dilute and semi-dilute regime, whose characteristic size are extracted by small angle X-ray and neutron scattering. Moreover, two sizes of objects are evidenced in dilute regime by dynamic light scattering: monomeric proteins with a size around 10 nm which can be associated to α/β, and γ-gliadins and polymeric glutenins with low molecular weight and polymeric assemblies with a size around 100 nm composed of ω-gliadins and glutenins polymers with high molecular weight. These assemblies are revealed by a combination of size exclusion chromatography and asymmetric flow field flow fractionation and allow one to rationalize the phase diagrams of the protein mixtures with temperature. The study of the dynamics of the phase separation of these protein mixtures by small angle X-ray scattering shows that the phase separation proceeds through a spinodal decomposition phenomenon. An arrested phase separation is observed for deep quenches but also at all temperature quenches for the most glutenin rich samples, which are gels in the monophasic regime, as confirmed by rheology
Fitzpatrick, Meriel E. J. "Turonian dinoflagellate cyst assemblages from southern England." Thesis, University of Plymouth, 1992. http://hdl.handle.net/10026.1/2029.
Full textMorin-Picardat, Emmanuelle. "Etudes d'auto-assemblages polydiacétylèniques et applications biologiques." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAF063/document.
Full textThe hydrophobic/hydrophilic duality of amphiphilic molecules is at the origin of their selfassembly in solution, into many supramolecular structures such as micelles. This thesis presents the formation, characterization and study of new photopolymerizable diacetylenic micelles. The first part describes the synthesis of new cationic micelles and the study of theiruse as gene transfer agent. In the second part, our work presents the study of polydiacetylene micelles, bearing polar heads octaétylèneglycol as potential drug delivery system. The encapsulation properties of these micelles were first evaluated in the presence of a fluorescent fullerene derivative. Then, the incorporation of a membrane probe in their lipophilic shell has allowed a study of their in vitro delivery properties. Finally a study of their in vivo biodistribution was also carried out by single photon emission tomography through the chelation of a radioactive isotope on micelle surface. Finally the last part presents theanalysis of two new tubularself-assemblies, obtained during our work
Couchaux, Maël. "Comportement des assemblages par brides circulaires boulonnées." Rennes, INSA, 2010. http://www.theses.fr/2010ISAR0030.
Full textThis thesis deals with the elastic and elasto-plastic behaviour of bolted circular flange joints used in steel structures. The aim of the work is to provide practical design methods for determining the static resistance of such flange joints as well as the stress concentration factors for the parts which are fatigue sensitive which are the tube wall at the weld toe and the bolts. In order to be able to cover the range of joint sizes that one finds in construction, three joint configurations were studied: L stubs under an axial load in the stem, flange joints with an axial applied to the connected tube and flange joints submitted to bending moments. The experimental, numerical and theoretical studies carried out on the three joint configurations are the subjects of chapters II, III and IV of the thesis. In chapter I the phenomena of surface contact between the adjacent flanges is clarified by a specially developed beam model whose validity is supported by the results from a finite element model including contact elements. To begin with a programme of tests was carried out for each of the joint configurations so as to obtain knowledge of their elastic and elasto-plastic behaviours and the results obtained are presented and discussed. Particular attention was paid to the study of the influence of bolt preloading and of out-of-plane imperfections of the flange surfaces on the elastic behaviour, in particular in relation to the tube wall stresses ranges at the weld toe and to the loading in the bolts which is essential information required for determining the fatigue life of those components. Since each specimen was loaded to failure, an experimental evaluation of the joint’s static resistance finally obtained. Using the ANSYS code, finite element models with brick elements and contact elements were developed for each of the joints configurations. The results from the finite element analyses were compared favourably with the test results both from the present testing but also from available published work. Thus validated, the finite element models were used to carry out parametric studies with the purpose of not only supplementing the experimental results but also to bring more light on certain aspects of the joint behaviour which could not be examined in sufficient detail during the test programme, such as the evolution of the contact zone with loading. Theoretical models were developed to describe the joint configuration behaviour in the elastic range, both for providing the stress concentration factors for the fatigue sensitive components and for estimating the joint stiffness. In order to determine the static resistances of flange joints, under axial load or under moment, theoretical limit state models are derived. The predictions of the joint behaviour and resistance models provide satisfactory results when compared to results both experimental and by finite element analyses. In all of the latter models the influence of contact is taken into account. Finally, based on the latter theoretical models, practical methods for determining design values of resistances of flange joints, under axial load, moment or a combination of moment and axial load, are proposed
Nagpal, Dua Neerja. "Acétylures métalliques fonctionnels pour des assemblages moléculaires." Rennes 1, 2007. http://www.theses.fr/2007REN1S049.
Full textIn the general framework of the use of organometallic complexes for optoelectronics, this thesis is devoted to the development of supramolecular materials with controlled architecture. Our aim was to synthesize alkynyl ruthenium building blocks, whose packing could be programmed. New monometallic and bimetallic complexes connected by conjugated nitrile bridges were elaborated starting from alkynyl ruthenium complexes. These synthesis were successfully directed towards the formation of either symmetrical or push-pull bimetallic complexes. The conception of functionalized alkynyl ruthenium to be included as building blocks of hydrogen bonded assemblies was considered using thymine and diaminotriazine groups as complementary units. The hydrogen bond driven self-association of these hybrid systems was studied by NMR
Michard, Frédéric. "Contraintes d'origine thermique dans les assemblages électroniques." Bordeaux 1, 1994. http://www.theses.fr/1994BOR10638.
Full textMoustafa, Khalil Ali. "Assemblages Polymétalliques Luminescents de L'ion Cu(I)." Thesis, Rennes, INSA, 2019. http://www.theses.fr/2019ISAR0018.
Full textThis manuscript describes in detail the reactivity of the pre-organized precursor A 1 , whose molecular formula is [Cu 2 (μ 2 -dppm) 2 (CN) 2 ](PF 6 ) 2 , based on Cu(I) ions with different types of ligands in order to synthesize new luminescent polymetallic assemblies. Its reactivity makes full use of the concepts of supramolecular chemistry guided by coordination chemistry (CDS), which makes it possible to obtain a large intricate number and varied polymetallic supramolecular assemblies of the Cu(I) ion. They are obtained from simple syntheses and with a wide variety of structural characteristics. Based on this result, we are interested to see how it is possible to extend the original adaptive coordination driven supramolecular approach developed in our group to the use of precursors bearing cyano fragments, such as K 2 M(CN) 4 (M= Ni, Pd, Pt), K 2 Pt(CN) 6 , K 4 M(CN) 8 (M= Mo and W) and also anionic inorganic precursors that do not have a metal centre, such as KC(CN) 3 , NaN(CN) 2 and NaN 3 .In the last chapter, the A 1 derivative has been reacted with pyridine- terminated polytopic ligands, which has made it possible to characterize novel coordination polymers. The new derivatives are characterized using different techniques such as multinuclear NMR, single-crystal and powder X-ray diffraction studies, UV-Vis and IR spectroscopies. In addition, the photophysical properties (emission spectrum, measurements of quantum yields and life times of the excited states) of the emissive materials obtained have been studied in solution and in the solid state at room temperature and at low temperature
Hamchaoui, Mohamed. "Conception économique des assemblages en construction métallique." Chambéry, 1997. http://www.theses.fr/1997CHAMS030.
Full textRagueb, Fouad. "Etude du comportement mecanique des assemblages brases." Paris, ENSAM, 1990. http://www.theses.fr/1990ENAM0014.
Full textAziz, Hazem. "Etude du dévissage spontané des assemblages boulonnés." Toulouse, INSA, 2003. http://www.theses.fr/2003ISAT0002.
Full textThis study is made with the aim of including how a bolted assembly loosens spontaneously under dynamic loadings. In a first time, we made a bibliographical study covering the various methods of loading, axial, transverse or in rotation, as well on the standards. We then approached an experimental study of spontaneous unscrewing under axial loadings. We defined, calculated and optimised a first experimental assembly working in resonance. We carried out then a second assembly using an inertial mass, which enabled us to observe spontaneous screwings and unscrewings. We also carried out tests under transverse loadings. Precise measures enabled us to determine thresholds of displacement of the clamped part from which unscrewing certainly occurs. We also obtained a threshold of slip of the screw head on its bearing surface, and a slip threshold of the threading, appreciably independent of the preload level. We modelled finally spontaneous unscrewing in first time analytically for a short screw then by finite elements for a long screw, and we proposed a criterion of the spontaneous unscrewing of the short screws
Rosa, Gonçalo Miranda. "Impact of emerging diseases on amphibian assemblages." Thesis, University of Kent, 2015. https://kar.kent.ac.uk/52449/.
Full textLélias, Guillaume. "Assemblages collés : modélisation, simulation et caractérisation expérimentale." Thesis, Toulouse, ISAE, 2016. http://www.theses.fr/2016ESAE0014/document.
Full textIn the frame of an internal research program called JoSAT (Joint Stress Analysis Tool), SogetiHigh Tech has suggested developing since 2008 a simplified tool for the stress analysis ofadhesively bonded joints. This tool allows for the distribution of both the internal forces anddisplacements in the adherends as well as the adhesive stresses along the overlap to beestimated from specified loads and boundary conditions, and has the advantage of beingextremely time saving compared to conventional Finite Element (FE) analyses.In 2011, this tool was extended to support adhesive material nonlinearities in the form ofspecified adhesive stress-strain evolution laws. However the theory developed wasdemonstrated as valid for the Single-Lap Joint (SLJ) configuration only, and limited to smalllevels of adhesive material nonlinearities. In this context, the objective of the thesis is double. First, extend and validate the simplified tool for the analysis of adhesively bonded joints in the case of nonlinear adhesive as well asadherends stress-strain constitutive behaviors. Then, suggest and develop experimentalprotocols for the characterization of the cohesive properties of thin adhesive layers so that thesimplified tool can be sustained with relevant experimental data in terms of adhesive stressstainconstitutive relationships
Zajicek, Petr. "Large rivers’ fish assemblages under multiple pressures." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19885.
Full textEuropean large rivers have been tremendously modified over centuries and transformed into waterways for inland navigation. Extensive river modifications such as river regulation, channel straightening and flood protection have resulted in multiple pressures. However, inland navigation has not been considered as a potential pressure yet. This thesis aimed to assess the role of inland navigation among the most prevailing pressures in large rivers under field conditions. A worldwide unique and complementary dataset, the Large River Fish Database (LRDB) was compiled. The LRDB consists of 2693 fish samples assessed at 358 sampling sites in 16 European large rivers. Sites were characterized by various pressure variables and frequencies of ship traffic. To derive representative samples of large rivers fish assemblages, performance of various fishing gears applied was assessed. Electrofishing samples represented highest densities of fish and highest overall biodiversity. Therefore, electrofishing is suitable for fish-based assessments of large rivers and only electrofishing samples were selected to assess multiple pressures and inland navigation. Commercial cargo navigation appeared as the most influential pressures on large rivers fish assemblages among increased velocities and the loss of floodplains. Starting at already eight passing vessels per day, densities of particularly habitat-sensitive spawners significantly declined. Moreover, recreational navigation such as river cruises and motorized sport boats had distinct ecological consequences to those of cargo vessels. Inland navigation is as detrimental as the hydromorphological degradation of the river channel and requires specific attention in river management and rehabilitation. Pleasure boating (river cruises and sport boats) will counteract river rehabilitation also in smaller waterways and delimit ecological success of the Blue Band initiative in Germany.
Fameau, Anne-Laure. "Assemblages d'acides gras : du volume aux interfaces." Nantes, 2011. http://www.theses.fr/2011NANT2022.
Full textThis work is part of the general understanding of the impact of the structure of a supramolecular assembly in solution on the interfacial and foaming properties. In the current context of sustainable development, we decided to choose as a model system assemblies produced from long fatty acids chain and hydroxylated derivatives, which are biomolecules from plant origin rarely used. First, a study was conducted in bulk, at the air/water interface and in foam, using tubes made of 12-hydroxystearic acid which exhibit a temperature tunable diameter. The tubes properties in bulk vary with the physic-chemical parameters. In addition, they adsorb at the air/water interface, with a similar behavior than for tubes in bulk upon heating. Very stable foams are obtained from this assembly. It is possible to modulate the foam stability by adjusting the temperature by modifying the structure of the assembly in situ in the Plateau border. It has been shown that the structure in bulk governs the interfacial properties and thus the control of the foaming properties was possible. Then, to obtain other information about the link between the structure of assemblies in bulk with the emulsifying and foaming properties, a study involving other assemblies has been initiated. Thus, it has been shown that for a given assembly, the foaming and emulsifying properties depend on the nature of the fatty acid
Pope, Matthew Ian. "The significance of biface-rich assemblages : an examination of behavioural controls on lithic assemblage formation in the lower palaeolithic." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270401.
Full textWASSEF, MAGDY. "Modelisation a la rupture d'un assemblage soude lors de refroidissement du cordon de soudure (application aux assemblages en croix)." Clermont-Ferrand 2, 1998. http://www.theses.fr/1998CLF22050.
Full textGarpe, Kajsa. "Effects of habitat structure on tropical fish assemblages." Doctoral thesis, Stockholm University, Department of Zoology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6767.
Full textRates of habitat alteration and degradation are increasing worldwide due to anthropogenic influence. On coral reefs, the loss of live coral reduces structural complexity while facilitating algal increase. In many coastal lagoons seagrass and corals are cleared to make room for cultivated macroalgae. This thesis deals with reef and lagoon habitat structure and how fish assemblage patterns may be related to physical and biological features of the habitat. It further examines assemblage change following habitat disturbance. Four studies on East African coral reefs concluded that both the abundance and species richness of recruit and adult coral reef fish were largely predicted by the presence of live coral cover and structural complexity (Papers I-III, VI). Typically, recruits were more selective than adults, as manifested by limited distributions to degraded sites. Paper VI compared short- and long-term responses of fish assemblages to the 1997-1998 bleaching event. The short-term response to coral mortality included the loss of coral dwelling species in favour of species which feed on algae or associated detrital resources. Counterintuitively, fish abundance and taxonomic richness increased significantly at one of two sites shortly after the bleaching. However, the initial increase was later reversed and six years after the death of the coral, only a limited number of fish remained. The influence of fleshy algae on fish assemblages was studied in algal farms (Paper IV), and examined experimentally (Paper V). The effects of algal farming in Zanzibar were significant. Meanwhile, manually clearing algal-dominated patch reefs in Belize from macroalgae resulted in short-term increases of abundance, biomass and activity of a few species, including major herbivores. The findings of this thesis demonstrate the significance of habitat as a structuring factor for tropical fish assemblages and predicts that coral death, subsequent erosion and algal overgrowth may have substantial deleterious impacts on fish assemblage composition, abundance and taxonomic richness, with recovery being slow and related to the recovery of the reef framework.