Дисертації з теми "Elasticity"
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1
Bosher, Simon Henry Bruce. "Non-linear elasticity theory." Thesis, Queen Mary, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407883.
2
Guerra, Rodrigo Emigdio. "Elasticity of Compressed Emulsions." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11694.
Анотація:
The interfaces of bubbles and droplets imbue foams and emulsions with extraordinary mechanical and chemical properties. The remarkably large interfacial area of these structures controls their thermodynamics and makes them practical and functional materials. When these interfaces are forced to touch, they can turn a dispersion of one fluid in another into a solid. These solid-like properties are evident in common household products such as shaving foam and mayonnaise, and our ability to control the fluid and solid properties of these materials is essential to their function.Physics
3
Lin, Peixiong. "Topics in nonlinear elasticity." Thesis, Heriot-Watt University, 1990. http://hdl.handle.net/10399/903.
4
Plakhtynska, V. V. "Market demand and elasticity." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/49033.
Анотація:
Demand shows the quantity of product, that people can and want to buy for this price. Demand determined by the solvent needs of buyers. It graphing, that shows such quantity of product, that needs demand at different prices and such quantity that consumers will buy at different prices.
5
Cousins, Christopher Stanley George. "Inner elasticity and the higher-order elasticity of some diamond and graphite allotropes." Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342008.
6
Mlčkovský, Petr. "Estimace determinant poptávky po příměstské vlakové dopravě v České republice." Master's thesis, Vysoká škola ekonomická v Praze, 2011. http://www.nusl.cz/ntk/nusl-124983.
Анотація:
This thesis analyzes railway demand and its determinants in the context of regional railway passenger transport in the Czech Republic and Prague suburban railway system. Special attention is devoted to examining the impact of new trains on the demand for the selected route of Jizerskohorské Railway. In particular models, I utilize as estimation procedure and difference-in-differences estimator. Panel data analysis found, in line with other published studies, short-run inelastic nature of demand. In order to increase revenue to railway operator, one must distinguish between a group of dependent and discretionary riders whose elasticity is different. Effect of buying new trains can be substantial, especially on less frequented routes with a greater proportion of private car holders.
7
Abeysekera, Jeffrey Michael. "Three dimensional ultrasound elasticity imaging." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57462.
Анотація:
Changes in tissue elasticity are correlated with certain pathological changes, such as localized stiffening of malignant tumours or diffuse stiffening of liver fibrosis or placenta dysfunction. Elastography is a field of medical imaging that characterizes the mechanical properties of tissue, such as elasticity and viscosity. The elastography process involves deforming the tissue, measuring the tissue motion using an imaging technique such as ultrasound or magnetic resonance imaging (MRI), and solving the equations of motion. Ultrasound is well suited for elastography, however, it presents challenges such as anisotropic measurement accuracy and providing two dimensional (2D) measurements rather than three dimensional (3D). This thesis focuses on overcoming some of these limitations by improving upon methods of imaging absolute elasticity using 3D ultrasound. In this thesis, techniques are developed for 3D ultrasound acquired from transducers fitted with a motor to sweep the image plane, however many of the techniques can be applied to other forms of 3D acquisition such as matrix arrays. First, a flexible framework for 3D ultrasound elastography system is developed. The system allows for comparison and in depth analysis of errors in current state of the art 3D ultrasound shear wave absolute vibro-elastography (SWAVE). The SWAVE system is then used to measure the viscoelastic properties of placentas, which could be clinically valuable in diagnosing preeclampsia and fetal growth restriction. A novel 3D ultrasound calibration technique is developed which estimates the transducer motor parameters for accurate determination of location and orientation of every data sample, as well as for enabling position tracking of a 3D ultrasound transducer so multiple volumes can be combined. Another calibration technique using assumed motor parameters is developed, and an improvement to an existing N-wire method is presented. The SWAVE research system is extended to measure shear wave motion vectors with a new acquisition scheme to create synchronous volumes of ultrasound data. Regularization based on tissue incompressibility is used to reduce noise in the motion measurements. Lastly, multiple ultrasound volumes from different angles are combined for measurement of the full motion vector, and demonstrating accurate reconstructions of elasticity are feasible using the techniques developed in this thesis.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
8
Maudarbocus, Sara. "Multipole Algorithms in Harmonic Elasticity." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523745.
9
Josefsson, Gabriella. "Elasticity of Cellulose Nanofibril Materials." Doctoral thesis, Uppsala universitet, Tillämpad mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-240250.
Анотація:
The demand for renewable load-carrying materials is increasing with increasing environmental awareness. Alternative sources for materials manufacturing and design have to be investigated in order to replace the non-biodegradable materials. The work presented in this thesis investigates structure-property relations of such renewable materials based on cellulose nanofibrils. Cellulose is the most abundant polymer on earth and exists in both ordered and disordered phases, where the ordered crystalline cellulose shows excellent mechanical properties. The celluloses nanofibril is composed of partly crystalline cellulose where the stiff crystal regions, or crystallites, are orientated in the axial direction of the fibrils. The cellulose nanofibrils have a high aspect ratio, i.e. length to diameter ratio, with a diameter of less than 100 nm and a length of some micrometres. In the presented work, different properties of the cellulose nanofibril were studied, e.g. elastic properties, structure, and its potential as a reinforcement constituent. The properties and behaviour of the fibrils were studied with respect to different length scales, from the internal structure of the cellulose nanofibril, based on molecular dynamic simulations, to the macroscopic properties of cellulose nanofibril based materials. Films and composite materials with in-plane randomly oriented fibrils were produced. Properties of the cellulose nanofibril based materials, such as stiffness, thickness variation, and fibril orientation distribution, were investigated, from which the effective elastic properties of the fibrils were determined. The studies showed that a typical softwood based cellulose nanofibril has an axial stiffness of around 65 GPa. The properties of the cellulose nanofibril based materials are highly affected by the dispersion and orientation of the fibrils. To use the full potential of the stiff fibrils, well dispersed and oriented fibrils are essential. The orientation distribution of fibrils in hydrogels subjected to a strain was therefore investigated. The study showed that the cellulose nanofibrils have high ability to align, where the alignment increased with increased applied strain.
10
Davies, Penny J. "Stability problems in nonlinear elasticity." Thesis, Heriot-Watt University, 1987. http://hdl.handle.net/10399/1020.
11
Duka, E. D. "Bifurcation problems in finite elasticity." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384747.
12
MeneÌndez-Conde, Lara Federico. "Scattering theory for isotropic elasticity." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249105.
13
Becker, Nils B. "Sequence dependent elasticity of DNA." Doctoral thesis, [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1186511923001-71752.
14
Wiesemann, Elizabeth Y. "The Visual Perception of Elasticity." TopSCHOLAR®, 2008. http://digitalcommons.wku.edu/theses/75.
15
Cooke, Tristrom Peter. "Some problems in anisotropic elasticity /." Title page, contents and summary only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phc773.pdf.
16
Jonák, Ondřej. "Odhad cenové elasticity poptávky po ropě." Master's thesis, Vysoká škola ekonomická v Praze, 2009. http://www.nusl.cz/ntk/nusl-15857.
Анотація:
Objective of this diploma thesis is estimation of price elasticity of crude oil demand. In order to calculation of such elasticity crude oil demand is estimated with econometrical methods. The choice of suitable model, which sufficiently and accurately models crude oil demand, is initial position of analysis. Consequently, crude oil demand is estimated from market data obtainable from public sources. This estimated model is verified from economic, statistic and econometric point of view. Consequently, price elasticity of crude oil demand is calculated from such model.
17
Dai, Liyang. "Elasticity in ferromagnetic shape memory alloys." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/2047.
Анотація:
Thesis (Ph.D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Material Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
18
Schwarz, Ulrich. "Forces and elasticity in cell adhesion." [S.l. : s.n.], 2004. http://pub.ub.uni-potsdam.de/2004/0034/schwarz.pdf.
19
Schwarz, Ulrich Sebastian. "Forces and elasticity in cell adhesion." Thesis, Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2005/110/.
Анотація:
Das Verhalten adhärenter Zellen hängt stark von den chemischen, topographischen und mechanischen Eigenschaften ihrer Umgebung ab. Experimentelle Untersuchungen der letzten Jahre haben gezeigt, dass adhärente Zellen aktiv die elastischen Eigenschaften ihrer Umgebung erkunden, indem sie an dieser ziehen. Der resultierende Kraftaufbau hängt von den elastischen Eigenschaften der Umgebung ab und wird an den Adhäsionskontakten in entsprechende biochemische Signale umgewandelt, die zelluläre Programme wie Wachstum, Differenzierung, programmierten Zelltod und Zellbewegung mitbestimmen. Im Allgemeinen sind Kräfte wichtige Einflussgrößen in biologischen Systemen. Weitere Beispiele dafür sind Hör- und Tastsinn, Wundheilung sowie die rollende Adhäsion von weißen Blutkörperchen auf den Wänden der Blutgefäße. In der Habilitationsschrift von Ulrich Schwarz werden mehrere theoretische Projekte vorgestellt, die die Rolle von Kräften und Elastizität in der Zelladhäsion untersuchen.(1) Es wurde eine neue Methode entwickelt, um die Kräfte auszurechnen, die Zellen an den Kontaktpunkten auf mikro-strukturierte elastische Substrate ausüben. Das Hauptergebnis ist, dass Zell-Matrix-Kontakte als Mechanosensoren funktionieren, an denen interne Kräfte in Proteinaggregation umgewandelt werden.
(2) Eine Ein-Schritt-Master-Gleichung, die die stochastische Dynamik von Adhäsionsclustern als Funktion von Clustergröße, Rückbindungsrate und Kraft beschreibt, wurde sowohl analytisch als auch numerisch gelöst. Zudem wurde dieses Modell auf Zell-Matrix-Kontakte, dynamische Kraftspektroskopie sowie die rollende Adhäsion angewandt.
(3) Im Rahmen der linearen Elastizitätstheorie und mit Hilfe des Konzepts der Kraftdipole wurde ein Modell formuliert und gelöst, das die Positionierung und Orientierung von Zellen in weicher Umgebung vorhersagt. Diese Vorhersagen sind in guter Übereinstimmung mit zahlreichen experimentellen Beobachtungen für Fibroblasten auf elastischen Substraten und in Kollagen-Gelen.
The behaviour of an adhering cell is strongly influenced by the chemical, topographical and mechanical properties of the surface it attaches to. During recent years, it has been found experimentally that adhering cells actively sense the elastic properties of their environment by pulling on it through numerous sites of adhesion. The resulting build-up of force at sites of adhesion depends on the elastic properties of the environment and is converted into corresponding biochemical signals, which can trigger cellular programmes like growth, differentiation, apoptosis, and migration. In general, force is an important regulator of biological systems, for example in hearing and touch, in wound healing, and in rolling adhesion of leukocytes on vessel walls. In the habilitation thesis by Ulrich Schwarz, several theoretical projects are presented which address the role of forces and elasticity in cell adhesion.
(1) A new method has been developed for calculating cellular forces exerted at sites of focal adhesion on micro-patterned elastic substrates. The main result is that cell-matrix contacts function as mechanosensors, converting internal force into protein aggregation.
(2) A one-step master equation for the stochastic dynamics of adhesion clusters as a function of cluster size, rebinding rate and force has been solved both analytically and numerically. Moreover this model has been applied to the regulation of cell-matrix contacts, to dynamic force spectroscopy, and to rolling adhesion.
(3) Using linear elasticity theory and the concept of force dipoles, a model has been introduced and solved which predicts the positioning and orientation of mechanically active cells in soft material, in good agreement with experimental observations for fibroblasts on elastic substrates and in collagen gels.
20
Ang, W. T. "Some crack problems in linear elasticity /." Title page, table of contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09pha581.pdf.
21
Green, Ellen Marie. "Mechanisms of elasticity in elastic proteins." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/4058.
Анотація:
This thesis investigates the mechanical properties of the elastic proteins isolated by cyanogen bromide digestion from lamprey cartilages and compares them with the mammalian protein, elastin. Thermomechanical testing and measurements of the effects of hydrophobic solvents on mechanics are used to determine the energetic and entropic contributions to the mechanical properties and the role of solvent interactions. Raman microspectrometry is shown to be a valuable tool in determining the secondary structure of the proteins, their interactions with water and molecular-level effects of mechanical strain. The supramolecular structure of the proteins matrices are investigated using nonlinear microscopy and X-ray diffraction. The mechanical properties of fibrous elastin agreed with those previously reported with elastic moduli in the region of 0.2-0.4 MPa. Elastic moduli decrease by approximately 25% with increased temperature, which was accompanied by a small decrease in hysteresis loss. In agreement with earlier findings, an entropic mechanism of elasticity became dominant only at high temperatures with a major contribution from interactions with solvent water. The lamprey proteins can be divided into two broad groups, the 'soft' branchial and pericardial cartilages resembling elastin, with linear stress-strain behaviour over a range of strains, elastic moduli in the range 0.13 MPa to 0.35 MPa, breaking strains of up to 50% and low hysteresis. Annular and piston proteins showed a very different response having much higher elastic moduli (0.27 MPa to 0.75 MPa), higher breaking strains and large hysteresis. Similarities between elastin and the lamprey matrix proteins extended to their thermomechanical behaviour with a decrease in elastic moduli and a drive towards entropic elasticity at high temperatures, although the annulus and piston were less thermally stable. Raman spectroscopy was able to detect differences between the various proteins and between elastin fibres and fragmentation products. Although no vibrational modes associated with cross-linking of the fibres could be identified, the secondary structure of dehydrated fibrous elastin was significantly different from \alpha -elastin. The former differed from previous experimental measurements, but was close to the theoretical predictions with 36% \beta -structures, 46% unordered and 18% \alpha -helix. \alpha -Elastin contained 29% \beta -structures, 53% unordered and 18% \alpha -helix. Strains of up to 60% in ligament fibre bundles resulted in no significant shifts in peak positions or in secondary structure. Polarization measurements revealed that the peptide bonds and several of the bulky side-chains re-orientated closer to the fibre axis with strain. Heating nuchal elastin fibres to 60^{\circ} C to increase the energetic component of the elasticity was associated with a 30% increase in the proportion of \beta -structures in the amide I band, a 50% increase in the amide III band, and a 50% reduction in the signal from bound water. The Raman spectra of the lamprey matrix proteins are similar both to each other and when compared to fibrous elastin. Only small differences could be detected in side-chain modes consistent with reported biochemical differences. Decomposition of the amide I band indicated that the secondary structures were also very similar to that of elastin, with a preponderance of unordered structures which probably confer the high degree of conformational flexibility necessary for entropy elasticity. Piston and annular proteins, like elastin, showed a strong interaction with water, suggesting a greater role of hydrophobic interactions in their mechanics compared to the branchial and pericardial proteins. Elastin is well known to exhibit autofluorescence. However, only the branchial protein has been reported to autofluoresce. This study shows that all four lamprey matrix proteins investigated exhibit strong autofluorescence which was subsequently exploited to image these tissues using multiphoton microscopy. Microscopic investigations revealed that the architecture of lamprey proteins differ from that of elastin. Nuchal elastin forms bundles of fibres running predominantly parallel to the direction of applied force. The arrangement in lamprey cartilage is very different forming honeycomb structures, which in the case of annular and piston cartilages, is surrounded by a dense sheath of matrix material. Dye injections revealed that the branchial and pericardial form open systems whereas in piston and annular cartilages a closed system exists. These variations in architecture are reflected in their different mechanical properties and in vivo functions.
22
Austin, D. M. "On two problems in linear elasticity." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378026.
23
Lloyd, James G. "The cavitation phenomenon in nonlinear elasticity." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589654.
Анотація:
This thesis studies the phenomenon of cavitation in nonlinear elasticity. In Chapter 2 we study the problem of cavitation in a ball of elastic material which is subjected to a radial dead-load on its boundary. We show that the rotationally symmetric equilibrium solution, in which a spherical cavity forms at the centre of the deformed ball, cannot be a global energy minimiser. This is achieved by proving the existence of a related axisymmetric homogeneous equilibrium with less energy (our arguments are related to the Rivlin instability in incompressible materials). In Chapter 3 we develop new necessary conditions for radially symmetric equilibria to be strong local minimisers of the energy. In Chapters 4 and 5 we study cavitation at, or near, the boundary of an elastic body. In Chapter 4 we consider cavitation occurring near the boundary of an elastic body occupying a half-space in its reference configuration. We show that the energy of such an equilibrium can be further lowered by moving the point of cavitation further away from the boundary. In Chapter 5, we prove existence of energy minimisers in classes of deformations which allow cavitation to occur at a boundary point.
24
Han, Rui. "Investigations into elasticity in cloud computing." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24714.
Анотація:
The pay-as-you-go model supported by existing cloud infrastructure providers is appealing to most application service providers to deliver their applications in the cloud. Within this context, elasticity of applications has become one of the most important features in cloud computing. This elasticity enables real-time acquisition/release of compute resources to meet application performance demands. In this thesis we investigate the problem of delivering cost-effective elasticity services for cloud applications. Traditionally, the application level elasticity addresses the question of how to scale applications up and down to meet their performance requirements, but does not adequately address issues relating to minimising the costs of using the service. With this current limitation in mind, we propose a scaling approach that makes use of cost-aware criteria to detect the bottlenecks within multi-tier cloud applications, and scale these applications only at bottleneck tiers to reduce the costs incurred by consuming cloud infrastructure resources. Our approach is generic for a wide class of multi-tier applications, and we demonstrate its effectiveness by studying the behaviour of an example electronic commerce site application. Furthermore, we consider the characteristics of the algorithm for implementing the business logic of cloud applications, and investigate the elasticity at the algorithm level: when dealing with large-scale data under resource and time constraints, the algorithm's output should be elastic with respect to the resource consumed. We propose a novel framework to guide the development of elastic algorithms that adapt to the available budget while guaranteeing the quality of output result, e.g. prediction accuracy for classification tasks, improves monotonically with the used budget. We demonstrate the application of the framework by developing two elastic data mining algorithms as examples. Experimental evaluations have been performed using prediction accuracy as the quality measure on real datasets. The results show that both algorithms indeed exhibit consistent increase in quality.
25
Дядечко, Алла Миколаївна, Алла Николаевна Дядечко, Alla Mykolaivna Diadechko, and N. V. Bondar. "The application of the elasticity theory." Thesis, Видавництво СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/17882.
26
Orekhov, Viktor Leonidovich. "Series Elasticity in Linearly Actuated Humanoids." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/71788.
Анотація:
Recent advancements in actuator technologies, computation, and control have led to major leaps in capability and have brought humanoids ever closer to being feasible solutions for real-world applications. As the capabilities of humanoids increase, they will be called on to operate in unstructured real world environments. This realization has driven researchers to develop more dynamic, robust, and adaptable robots.
Compared to state-of-the-art robots, biological systems demonstrate remarkably better efficiency, agility, adaptability, and robustness. Many recent studies suggest that a core principle behind these advantages is compliance, yet there are very few compliant humanoids that have demonstrated successful walking.
The work presented in this dissertation is based on several years of developing novel actuators for two full-scale linearly actuated compliant humanoid robots, SAFFiR and THOR. Both are state-of-the-art robots intended to operate in the extremely challenging real world scenarios of shipboard firefighting and disaster response.
The design, modeling, and control of actuators in robotics application is critical because the rest of the robot is often designed around the actuators. This dissertation seeks to address two goals: 1) advancing the design of compliant linear actuators that are well suited for humanoid applications, and 2) developing a better understanding of how to design and model compliant linear actuators for use in humanoids.
Beyond just applications for compliant humanoids, this research tackles many of the same design and application challenges as biomechanics research so it has many potential applications in prosthetics, exoskeletons, and rehabilitation devices.Ph. D.
27
Kessler, Eli Mikael. "One Hundred and Fifty Percent Elasticity." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/649.
Анотація:
The sculptural environments I create immerse the viewer in a decrepit vaudevillian past. The sculptures allude to narratives within Community Theater as well as the Drag Show. Making becomes an act; manipulating materials such as synthetic hair and paint are associated with the guise of the makeup artist. Frantic rehearsal logic prevails as a dress is repurposed into a male giant's costume and window blinds are used to construct a boat's deck. This collusion asks the viewer to transgress the boundary of the stage, becoming a voyeur privileged to the world of exiled props and role reversal.
28
Strack, Florian. "Birefringence and elasticity of overstreched DNA /." [S.l. : s.n.], 1999. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8575309.
29
Strack, Florian. "Birefringence and elasticity of overstretched DNA." [S.l.] : Universität Konstanz , Fakultät für Physik, 1999. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8501020.
30
Sladescu, Matthew. "Proactive Event Aware Cloud Elasticity Control." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14185.
Анотація:
An event that can attract the interest of a large internet populace, can bring about large bursts in demand for event-associated resources. This phenomenon is notorious for degrading the QoS of numerous web-applications overwhelmed with workload bursts that accompany events like online ticket releases, sales events and result announcements. Such reduced QoS can translate to reduced revenue and degraded reputation for application providers. While cloud computing has the potential to alleviate this problem by offering computing resources on an as-needed basis to match event-associated demand, important challenges remain in finding the right resource control strategies to cost-effectively scale resources, and in overcoming the initialisation lag associated with resource acquisition. This thesis recognises an implicit link between events and bursts, and introduces event-aware burst modelling and burst prediction techniques that can forecast the time, shape, magnitude and length of event-associated workload bursts. We show how these techniques can assist application providers in making more informed decisions about when to acquire and release resources to match event-associated demand, in order to maintain application QoS during event-associated bursts.
31
Haldar, Tapati. "On some problems of thermo-elasticity." Thesis, University of North Bengal, 1995. http://hdl.handle.net/123456789/1038.
32
Abidi, Sonia. "Matériaux composites à haute tenue thermique : influence de la micro-nanostructure sur les transferts moléculaires, électroniques et thermiques." Thesis, Toulon, 2014. http://www.theses.fr/2014TOUL0019/document.
Анотація:
Les matériaux de protection incendie sont largement utilisés pour assurer la sécurité des usagers des infrastructures. Les normes de protection incendie évoluant régulièrement, les matériaux doivent être de plus en plus performants. Ceux-ci sont généralement des mortiers constitués d’oxydes réfractaires et isolants. L’objectif de ce travail est de mettre au point un composite coupe-feu 4 h applicable par projection mais également de déterminer ses propriétés thermiques et mécaniques.Dans une première partie, cette étude reprend les différentes étapes de l’élaboration d’un matériau de protection incendie, après la présentation de la démarche qui a guidé l’élaboration de nos matériaux, nous nous sommes intéressés plus particulièrement à la composition chimique de la matrice ainsi que celle du ciment. Leurs propriétés thermiques et mécaniques ont été passées en revue.Les matières premières nécessaires à l’élaboration d’un mortier ont ensuite été sélectionnées. L’évolution, respectivement de la conductivité thermique, de la diffusivité, de la porosité, de la chaleur spécifique et des propriétés mécaniques des mortiers choisis en fonction de la nature et de la quantité de charges incorporées à la matrice a été étudiée. Une description des divers modèles analytiques et numériques permettant la représentation de la conductivité thermique et du module d’Young des matériaux a permis de développer un modèle capable de prédire le comportement thermique et mécanique des composites en fonction de la nature et de quantité de charges ajoutées.Dans une seconde partie, la cinétique de la réaction d’hydratation du plâtre afin de maîtriser les temps de prise et pour faciliter la production des projetés dans la chaîne industrielle a été étudiée. L’influence sur la cinétique d’hydratation, de la composition chimique du plâtre, de sa granulométrie et de l’ajout d’adjuvants couramment utilisés dans l’industrie plâtrière, a également été traitée.10A l’issue de cette étude, deux formulations de composites projetables ont été mises au pointFire protection materials are widely used to ensure the safety of users of the infrastructure. Standards of fire protection regularly operating, the materials must be more efficient. These are generally composed of refractory mortar and insulating oxides. The objective of this work is to develop a firewall composite 4 h applied by projecting but also to determine the thermal and mechanical properties.In the first part, this study describes the various stages of the development of a fire protection material, after the presentation of the approach that has guided the development of our materials, we are interested especially in the chemical composition of the matrix and that of the cement. Their thermal and mechanical properties have been reviewed.The raw materials for the preparation of mortar were selected. The evolution respectively of thermal conductivity, diffusivity, porosity, specific heat and the mechanical properties of mortars chosen according to the nature and amount of the fillers incorporated in the matrix has been studied. A description of the various analytical and numerical models for the representation of the thermal conductivity and Young's modulus of the materials led to the development of a model able to predict the thermal and mechanical behavior of composites based on the nature and amount of charges added.In a second part, the kinetics of the hydration reaction of gypsum to control setting time and to facilitate the production of the composite in the industrial chain was studied. The influence on the kinetics of hydration, of the chemical composition of the gypsum, particle size distribution and the addition of adjuvant commonly used in the plaster industry, has also been treated.At the end of this study, two formulations of composites applied by projection were developed
33
Pimienta, Lucas. "Effet des Fluides et des Fréquences sur les propriétés élastiques des grès et carbonates." Thesis, Paris, Ecole normale supérieure, 2015. http://www.theses.fr/2015ENSU0002/document.
Анотація:
La sismique et la sismologie sont des moyens puissants pour comprendre la croûte terrestre.Ces deux méthodes reposent notamment sur une compréhension approfondie de la propagation des ondes sismiques dans des milieux sédimentaires saturés en fluides.Ce travail a pour but de comprendre les effets statique et dynamique du fluide sur la réponse élastique de roches clastiques saturées.Deux points spécifiques de l'interaction fluide-roche sont étudiées: (i) l'intéraction physico-chimique, le « shear weakening », affectant la réponse élastique de la roche; et (ii) l'interaction mécanique, le « frequency effect », induisant une dépendance des propriétés élastiques à la fréquence de mesure.Deux types de roches sont étudiés: les grès et les calcaires.Ces échantillons de roche sont sélectionnés pour leurs propriétés isotropes et leur forte concentration en un minéral dominant: le quartz pour les grès et la calcite pour les carbonates.Le phénomène de « shear weakening » est d’abord étudié pour de très faibles saturations en eau afin de tester l’effet de l'adsorption.Aucun affaiblissement n’est mesuré dans les carbonates, au contraire un affaiblissement élastique global est observé dans certains grès : Les modules de cisaillement et d’incompressibilité sont également affectés.L'effet ne semble pas provenir d'une différence intrinsèque entre les minéraux de quartz et de calcite, mais d’une différence microstructurale entre roches. Un modèle micromécanique est développé, montrant que les deux paramètres clef sont le caractère granulaire et le degré de cimentation de la roche.Le même résultat est obtenu pour les compressibilités mesurées lors des saturations totales en eau.Ces deux études montrent que l'adsorption est la cause du « shear weakening », et implique un affaiblissement élastique global dans les roches granulaires peu cimentées (gréseuses et probablement carbonatées).L'effet de fréquence est étudié dans des grès de Fontainebleau et de Berea. Deux méthodes sont étudiées, toutes deux basées sur le principe de "stress-strain" (i.e. contrainte-déformation): l'oscillation "isotrope" (de la pression de confinement) et "déviatorique" (de la contrainte déviatorique).Ces deux modes d'oscillations sont tout d’abord calibrés à l’aide de plusieurs standards (e.g. aluminium, verre, gypse, plexiglass).Les échantillons de roche, saturés par des fluides de différentes viscosités, sont ensuite mesurés avec ces deux modes d'oscillation.Pour le premier mode d'oscillation, dit "isotrope", ce travail a permis de (i) mettre en évidence trois régimes élastiques distincts;et (ii) mesurer à la fois la conséquence (i.e. dispersion et atténuation du module d'incompressibilité) et la cause (i.e. écoulement fluide global) de la transition en fréquence entre état drainé et état non-drainé.Pour le second mode d'oscillation, dit "déviatorique", le module de Young et le coefficient de Poisson sont mesurés sur une gamme de fréquence apparente de [10-3;105] Hz.Pour un échantillon de grès de Fontainebleau, les deux transitions élastiques sont observées. Les mesures sont cohérentes avec les théories existantes.Un modèle 1D, prenant en compte les conditions de bord du système, est finalement développé. Ce modèle donne des résultats cohérents, et explique l'effet du volume mort sur les propriétés mesurées dans le cas d'une oscillation « isotrope »Seismics or Seismology are powerful tools to investigate Earth's crust. However, both rely on seismic waves that travelled through fluid-saturated sedimentary layers. This work, mainly experimental, aims at understanding the static and dynamic effects of the saturating fluid on the elastic response of clastic rocks.In this framework, two specific studies are emphasized:(i) the rock-fluid physico-chemical interaction, often addressed as the "shear weakening" effect, thought to affect the rock overall elastic response; and (ii) the rock-fluid mechanical interaction, addressed as "frequency effect", thought to induce a dependence of elastic properties to the measuring frequency.Two main rock types are investigated: Sandstone and Limestone. All rock samples are chosen to be isotropic and composed of a dominant mineral content, i.e. quartz for sandstone and calcite for limestone
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Heussinger, Claus. "On the Elasticity of Stiff Polymer Networks." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-77447.
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O, Makhmudov, I. Niyozov, and Nicolai Tarkhanov. "The cauchy problem of couple-stress elasticity." Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2009/3007/.
Анотація:
We study the Cauchy problem for the oscillation equation of the couple-stress theory of elasticity in a bounded domain in R3. Both the displacement and stress are given on a part S of the boundary of the domain. This problem is densely solvable while data of compact support in the interior of S fail to belong to the range of the problem. Hence the problem is ill-posed which makes the standard calculi of Fourier integral operators inapplicable. If S is real analytic the Cauchy-Kovalevskaya theorem applies to guarantee the existence of a local solution. We invoke the special structure of the oscillation equation to derive explicit conditions of global solvability and an approximation solution.
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Sherif, Feysel Nesru. "MATLAB FEM Code - From Elasticity to Plasticity." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18638.
Анотація:
A MATLAB Finite Element code for plane strain analysis of footings on an Elasto-plastic material using the Mohr Coulomb failure criteria has been developed. The first step is to develop codes for mesh generation and Gaussian numerical integration. Next, the force matrix, the stiffness matrix and the self weight matrix are assembled. After that functions for non linear analysis such as the plastic potential derivatives are formed. Finally plots of the mesh, displacement shadings, stress shadings and stress-strain curves are developed. For the purpose of verification results from the code for biaxial test are compared with the theoretical solution. Additionally comparison is made between the code and prandtl’s bearing capacity solutions for a footing problem. These results show that accuracy depends on two factors: - the type of the element and the number of elements used. The three node triangular element and the four node rectangular element give less accurate results when compared to higher order element types. And for a relatively accurate result the number of elements should be too high.
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Zhu, Yanying. "The development of displacement-based toroidal elasticity." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/9990.
Анотація:
Toroidal Elasticity (TE) is a three-dimensional theory used for the elastostatic analysis of thick-walled curved pipes, elbows, and toroidal shells. A displacement-based approach to TE is used in the present study, and analytical solutions are set up using the method of successive approximations. Three problems are solved analytically for the first time to illustrate the approach. The first problem concerns a 90$\sp\circ$ cantilevered elbow subjected to an out-of-plane couple at the free end. A real form general solution is developed up to the third order approximation, and results obtained are compared with boundary element results. The second problem concerns an axisymmetric sectorial toroidal ring subjected to loads on its radial surfaces. A complex form solution is developed with the aid of homogeneous eigenfunctions. Numerical results obtained are compared with finite element results. The third problem concerns a toroidal shell subjected to band loads of normal pressure. The applied loading is expanded in a Fourier series, and analytical solutions are developed for each term of the series. Numerical results are computed and again are compared with finite element results. The present work demonstrates the use of displacement based TE for the analytical prediction of displacement and stress in toroidal geometries, and the agreement between the displacement based TE solution and numerical results.
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Lee, Chang-Kye. "Gradient smoothing in finite elasticity : near-incompressibility." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/94491/.
Анотація:
This thesis presents the extension of the gradient smoothing technique for finite element approximation (so-called Smoothed Finite Element Method (S-FEM)) and its bubble-enhanced version for non-linear problems involving large deformations in nearly-incompressible and incompressible hyperelastic materials. Finite Element Method (FEM) presents numerous challenges for soft matter applications, such as incompressibility, complex geometries and mesh distortion from large deformation. S-FEM was introduced to overcome the challenges mentioned of FEM. The smoothed strains and the smoothed deformation gradients are evaluated on the smoothing domain selected by either edge information, nodal information or face information. This thesis aims the extension of S-FEM in finite elasticity as a means of alleviating locking and avoiding mesh distortion. S-FEM employs a “cubic” bubble enhancement of the element shape functions with edge-based and face-based S-FEMs, adding a linear displacement field at the centre of the element. Thereby bubble-enhanced S-FEM affords a simple and efficient implementation. This thesis reports the properties and performance of the proposed method for quasi-incompressible hyperelastic materials. Benchmark tests show that the method is well suited to soft matter simulation, overcoming deleterious locking phenomenon and maintaining the accuracy with distorted meshes.
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Meyer, Arnd, and Roman Unger. "Projection methods for contact problems in elasticity." Universitätsbibliothek Chemnitz, 2006. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200601436.
Анотація:
The aim of the paper is showing, how projection methods can be used for computing contact problems in elasticity for different classes of obstacles. Starting with the projection idea for handling hanging nodes in finite element discretizations the extension of the method for handling penetrated nodes in contact problems will be described for some obstacle classes.
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Albonico, Michel. "Controlling Cloud-Based Systems for Elasticity Testing." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0027/document.
Анотація:
Les systèmes déployés dans être testés pendant l’élasticité, ce qui entraîne plusieurs problématiques. D’abord, l’exécution d’un test pendant l’élasticité peut exiger de conduire le CBS dans une succession de comportements élastiques spécifiques, càd., une séquence d’ajout/retrait de ressources, qui nécessite des variations précises de la charge des requêtes envoyées au cloud. Seconde, certaines adaptations du CBS ne sont réalisées qu’à un moment précis, par exemple après un ajout de ressources et, par conséquent, leurs tests doivent être synchronisés avec des états spécifiques du CBS. Troisième, les testeurs doivent rejouer les tests pendant l’élasticité de manière déterministe afin de déboguer et corriger le CBS. Quatrième, la création des tests pendant l’élasticité est complexe et laborieuse dû au large nombre de paramètres, et à la particularité du cloud computing. Enfin, seulement quelques combinaisons de paramètres peuvent causer des problèmes au CBS, que les cas de test créés au hasard peuvent manquer, alors qu’un jeu de tests couvrant toutes les combinaisons possibles serait trop grand et impossible à exécuter. Dans cette thèse, nous abordons toutes ces problématiques en proposant plusieurs approches :1) une approche qui conduit les CBSs dans une suite de comportements élastiques prédéfinis, 2) une approche qui synchronise l’exécution des tests selon les états du CBS, 3) une approche qui permette la reproduction des tests pendant l’élasticité, 4) un langage spécifique à ce domaine (DSL, selon l’acronyme anglais) qui résume la mise en œuvre des tests pendant l’élasticité, 5) une approche qui génère des petits ensembles de tests pendant l’élasticité tout en révélant des problèmes liés à l’élasticitéSystems deployed on elastic infrastructures deal with resource variations by adapting themselves, which may cause errors, or even degrade their performance. Therefore, we must test the Cloud-Based Systems(CBSs) throughout elasticity, which faces problematics. First, executing elasticity tests may require the lead of CBS throughout a specific elastic behavior, i. e.,sequence of resource changes, which depends on an accurate workload generation. Second, CBS adaptations occur at a precise moment, such as after a resource scale out, which requires to test them during a specific CBS states. Third, testers must re-execute elasticity tests in a deterministic manner to debug and fix the CBS. Fourth, implementing elasticity tests is complex and laborious given the wide possibility of parameters, and the peculiarity of cloud computing. Finally, specific combinations of parameters may cause the system issues, where random tests may miss such combinations, while a test set that covers all thecombinations may be large and impractical to execute. In this thesis, we tackle all these five problematics by proposing several approaches: 1) an approach to drive the CBS throughout preset elastic behaviors, 2) an approach to synchronize tests according to the CBS states, 3) an approach to enable reproducing elasticity testing, 4) a Domain Specific Language (DSL)-basedapproach to abstract the elasticity testing implementation, and 5) an approach to generate small sets of tests that reveal relevant elasticity-related issues
41
Shen, Xiaofeng. "Integral equation methods in anti-plane elasticity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq22672.pdf.
42
Khisaeva, Zemfira F. "Scale effects in finite elasticity and thermoelasticity." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102990.
Анотація:
The main focus of this thesis is on investigating the minimum size of the Representative Volume Element (RVE) and finite-size scaling of properties of random linear and nonlinear elastic composites. The RVE is a material volume which accurately describes the overall behavior of a heterogeneous solid, and is the core assumption of continuum mechanics theory. If the composite microstructure admits the assumption of spatial homogeneity and ergodicity, the RVE can be attained within a specific accuracy on a finite length-scale. Determining this scale is the key objective of this thesis.In order to theoretically analyze the scale-dependence of the apparent response of random microstructures, essential and natural boundary conditions which satisfy Hill's averaging theorem in finite deformation elasticity are first considered. It is shown that the application of the partitioning method and variational principles in nonlinear elasticity and thermoelasticity, under the two above-mentioned boundary conditions, leads to the hierarchy of mesoscale bounds on the effective strain- and free-energy functions, respectively. These theoretical derivations lay the ground for the quantitative estimation of the scale-dependence of nonlinear composite responses and their RVE size.
The hierarchies were computed for planar matrix-inclusion composites with the microstructure modeled by a homogeneous Poisson point field. Various nonlinear composites with Ogden-type strain-energy function are considered. The obtained results are compared with those where both matrix and inclusions are described by a neo-Hookean strain-energy function as well as with the results obtained from the linear elasticity theory. The trends toward the RVE are also computed for nonlinear elastic composites subjected to non-isothermal loading. The accuracy of the RVE size estimation is calculated in terms of the discrepancy between responses under essential and natural boundary conditions. Overall, the results show that the trends toward the RVE as well as its minimum size are functions of the deformation, deformation mode, temperature, and the mismatch between material properties of the phases.
The last part of the thesis presents an investigation of the size effect on thermoelastic damping of a micro-/nanobeam resonator. It does not follow the framework described above. The main concern here is the size and the vibration frequency, at which the classical Fourier law of heat conduction is no longer valid, and the finite speed of heat propagation has to be taken into account.
43
Barnett, D. N. "Convection, elasticity and flexure inside terrestrial planets." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596394.
Анотація:
In this dissertation, the large-scale geophysical behaviour of the Earth, Venus and Mars are compared, using data collected by the Magellan spaceprobe (for Venus) and the Viking and Mars Global Surveyor (MGS) probes (for Mars). Neither Venus nor Mars show evidence of plate tectonics operating at the present day. On Venus, the lack of water means the frictional resistance at faults and the viscous drag on the base of the moving lithospheric plates are too high to be overcome by the driving forces for plate tectonics. The high elastic thickness of Mars results in a large frictional resistance to fault motion, although the faults themselves are probably no stronger than those on the Earth, and means large compressive stresses are required to initiate subduction. The likely high viscosity of the martian mantle, a consequence of its probable dryness and low temperature, may also result in large drag forces on the base of the lithosphere. Plate tectonics may have operated in the past on both planets, providing a possible explanation for the rapid resurfacing of Venus required by the crater counts and the linear magnetic anomalies recently discovered on Mars.
44
Buchholz, Simon Hendrik [Verfasser]. "Renormalisation in discrete elasticity / Simon Hendrik Buchholz." Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/1198933607/34.
45
Rajagopalan, Shriram. "System support for elasticity and high availability." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46272.
Анотація:
Elasticity and high availability (HA) are key requirements among modern Internet applications. Elasticity enables applications to dynamically allocate/release physical resources in proportion to request load. High availability enables applications to mask failures in the system from end users. In current practice, every application implements these features as part of its own application logic, resulting in unnecessary design complexity. This thesis argues that facilities for elasticity and HA should be exposed as system-level primitives, in the same way abstractions for files and networks became operating system-level primitives three decades ago. Unfortunately, providing these higher-level services efficiently may require knowledge of application data structures, consistency requirements, and workloads. This thesis describes initial instantiations of such interfaces for two broad (and different) classes of applications: network middleboxes (e.g., load balancers, intrusion prevention systems, etc) and database systems. Elasticity is achieved typically through dynamic partitioning of state and inputs into independent subsets, while HA is achieved through state replication. Guided by this principle, this thesis presents a system-level runtime that partitions the middlebox state along flow boundaries and provides abstractions for elasticity and HA using live migration and replication of flows respectively. For database systems, this thesis presents a hypervisor-level HA system that performs database-aware virtual machine replication, eliminating the need for complex application-level HA mechanisms.
This thesis concludes that while there may not be a one-size-fits-all solution to application elasticity and HA, it is still feasible and beneficial to provide system-level primitives that are applicable across one or more application domains.
46
Jones, Janette Louise. "The elasticity and growth of rigid networks." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359808.
47
Kutter, Samuel. "Elasticity of polymers with internal topological constraints." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619538.
48
Uchida, Nariya. "Elasticity of disordered nematic liquid-crystalline gels." 京都大学 (Kyoto University), 2000. http://hdl.handle.net/2433/86453.
49
Lu, Minhua. "Elasticity and polarizations in ferroelectric liquid crystals." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1060708174.
50
Minami, Akihiko. "Theoretical study of phase transitions with elasticity." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136862.