14 results on '"ELASTICITE"'
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2. Risk-averse estimates of effective properties in heterogeneous elasticity.
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Bleyer, Jeremy
- Subjects
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CONDITIONAL expectations , *DISTRIBUTION (Probability theory) , *ELASTICITY , *RANDOM variables , *OPTIONS (Finance) , *INHOMOGENEOUS materials - Abstract
In this work, we propose a theoretical framework for computing pessimistic and optimistic estimates of effective properties in the case of heterogeneous elastic materials with uncertain microscopic elastic properties. We rely on a risk-averse measure widely used in finance called the conditional-value at risk (CVaR). The CVaR computes the conditional expectation of events occurring above a given risk level, thereby characterizing the extreme tails of the probability distribution of a random variable. In the context of elastic materials, we propose to use the CVaR on the elastic free energy to compute an optimistic estimate of the global stiffness for some confidence level α. Similarly, we also use the CVaR on the complementary elastic energy to compute a pessimistic estimate of the global stiffness. The obtained CVaR estimates benefit from a convex optimization formulation. The resulting material behavior is still elastic but not necessarily linear anymore. We discuss approximate formulations recovering a linear elastic behavior. We apply the proposed formulations to the micromechanical estimates of effective elastic properties of random heterogeneous materials. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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- View/download PDF
3. MODÈLE D’ ÉLASTICITÉ DE PRIX/DEMANDE DU POINT DE VUE BAYÉSIEN : LE CAS D’ UNE ENTREPRISE DE DÉTAIL CHILIENNE.
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GONZÁLEZ, Camilo
- Abstract
Copyright of Revue Internationale des Économistes de Langue Française (RIELF) is the property of Poznan University of Economics & Business and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
- Full Text
- View/download PDF
4. Immediate Effect of Dry Needling on the Viscoelastic Properties of a Trigger Point on the Infraspinatus Muscle Measured with MyotonPRO.
- Author
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Roch, Mélanie, Morin, Mélanie, and Gaudreault, Nathaly
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CHRONIC pain treatment ,SHOULDER pain treatment ,STATISTICS ,ANALYSIS of variance ,ELASTICITY ,ONE-way analysis of variance ,TREATMENT effectiveness ,DESCRIPTIVE statistics ,QUESTIONNAIRES ,RESEARCH funding ,DATA analysis ,DATA analysis software ,MYOFASCIAL pain syndrome treatment ,ROTATOR cuff - Abstract
Copyright of Physiotherapy Canada is the property of University of Toronto Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
5. Fluid-structure interaction problems inspired by the nectar capture in bees
- Author
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Brau, Fabian, Kozyreff, Gregory, Damman, Pascal, Bico, José, Brun, Pierre-Thomas, Domino, Lucie, Terwagne, Denis, Vella, Dominic D.V., Hua, Hoa Ai Béatrice, Brau, Fabian, Kozyreff, Gregory, Damman, Pascal, Bico, José, Brun, Pierre-Thomas, Domino, Lucie, Terwagne, Denis, Vella, Dominic D.V., and Hua, Hoa Ai Béatrice
- Abstract
Capturing viscous fluid efficiently is a challenge that nectarivores overcame through thecourse of evolution to collect this primary source of energy. The understanding of theirdrinking mechanisms are sources of inspiration for biomimetic applications such ascontrolled fluid capture devices. The physical ingredients intervening in those processes areviscosity, capillarity, and elasticity. Viscosity has two antagonistic roles, it can hinder thefluid capture, during suction for example, whereas it can help increase the volume of fluidcaptured in a dipping process through a Landau-Levich-Derjaguin (LLD) mechanism. Formost nectarivores, capillarity dominates over gravity given their typical size. The surfacetension can induce a spontaneous rise of liquids and deformations when a soft solid is at anair-liquid interface. The elasticity of the tongues and of the various elements composing itcan thus also play a role in fluid capture. In this thesis, we aim to study bioinspired fluidcapture through elastocapillary and viscous effects.The various problems studied here are inspired by the nectar capture in bees and similarpollinators. Bees feed by dipping periodically their tongue in nectar at a constant frequency.The amount of fluid collected per unit time (ingestion rate) should thus increase with thenectar viscosity according to the LLD theory. However, a drop of the ingestion rate isobserved experimentally when the nectar viscosity exceed some threshold. This observationleads us to consider the fine structure of the tongue composed of a glossa decorated byslender papillae which open, as the hair of a paintbrush, when immersed in a liquid. Wethus propose to consider the relaxation dynamic of the papillae when they are immersed inthe nectar. To do so, we study the relaxation movement of a bent rod immersed in a viscousfluid. We use the linear beam equation supplemented by a viscous drag term varyingnonlinearly with the rod velocity. Different relaxation dynamics are identif, Doctorat en Sciences, info:eu-repo/semantics/nonPublished
- Published
- 2023
6. Bioinspired shape shifting of liquid-infused ribbed sheets
- Author
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Cappello, Jean, Scheid, Benoît, Brau, Fabian, Siefert, Emmanuel, Cappello, Jean, Scheid, Benoît, Brau, Fabian, and Siefert, Emmanuel
- Abstract
The recent emergence of stimuli-responsive, shape-shifting materials offers promising applications in fields as different as soft robotics, aeronautics, or biomedical engineering. Targeted shapes or movements are achieved from the advantageous coupling between some stimulus and various materials such as liquid crystalline elastomers, magnetically responsive soft materials, swelling hydrogels, etc. However, despite the large variety of strategies, they are strongly material dependent and do not offer the possibility to choose between reversible and irreversible transformations. Here, we introduce a strategy applicable to a wide range of materials yielding systematically reversible or irreversible shape transformations of soft ribbed sheets with precise control over the local curvature. Our approach-inspired by the spore-releasing mechanism of the fern sporangium-relies on the capillary deformation of an architected elastic sheet impregnated by an evaporating liquid. We develop an analytical model combining sheet geometry, material stiffness, and capillary forces to rationalize the onset of such deformations and develop a geometric procedure to inverse program target shapes requiring fine control over the curvature gradient. We finally demonstrate the potential irreversibility of the transformation by UV-curing a photosensitive evaporating solution and show that the obtained shells exhibit enhanced mechanical stiffness., SCOPUS: ar.j, info:eu-repo/semantics/published
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- 2023
7. Elasticity and substitutability of food demand and emerging disease risk on livestock farms
- Author
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Delabouglise, Alexis, Fournié, Guillaume, Peyre, Marie-Isabelle, Antoine-Moussiaux, Nicolas, Boni, Maciej F., Delabouglise, Alexis, Fournié, Guillaume, Peyre, Marie-Isabelle, Antoine-Moussiaux, Nicolas, and Boni, Maciej F.
- Abstract
Disease emergence in livestock is a product of environment, epidemiology and economic forces. The environmental factors contributing to novel pathogen emergence in humans have been studied extensively, but the two-way relationship between farm microeconomics and outbreak risk has received comparably little attention. We introduce a game-theoretic model where farmers produce and sell two goods, one of which (e.g. pigs, poultry) is susceptible to infection by a pathogen. We model market and epidemiological effects at both the individual farm level and the community level. We find that in the case of low demand elasticity for livestock meat, the presence of an animal pathogen causing production losses can lead to a bistable system where two outcomes are possible: (i) successful disease control or (ii) maintained disease circulation, where farmers slaughter their animals at a low rate, face substantial production losses, but maintain large herds because of the appeal of high meat prices. Our observations point to the potentially critical effect of price elasticity of demand for livestock products on the success or failure of livestock disease control policies. We show the potential epidemiological benefits of (i) policies aimed at stabilizing livestock product prices, (ii) subsidies for alternative agricultural activities during epidemics, and (iii) diversifying agricultural production and sources of proteins available to consumers.
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- 2023
8. StreamCloud: An Elastic Parallel-Distributed Stream Processing Engine
- Author
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Gulisano, Vincenzo, Jiménez Peris, Ricardo, Valduriez, Patrick, Distributed Systems Laboratory (DSL), Universidad Politécnica de Madrid (UPM), Scientific Data Management (ZENITH), Laboratoire d'Informatique de Robotique et de Microélectronique de Montpellier (LIRMM), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Inria Sophia Antipolis - Méditerranée (CRISAM), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Universidad Politécnica de Madrid, Ricardo Jiménez Peris, Patrick Valduriez(Patrick.Valduriez@inria.fr), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Inria Sophia Antipolis - Méditerranée (CRISAM)
- Subjects
Informática ,Telecomunicaciones ,Elasticidad ,Scalability ,Fault Tolerance ,Stream Processing Engine ,Data Streaming ,Elasticity ,Load Balancing ,Sistemas de procesamiento de flujos de datos ,Equilibrado de Carga ,Tolerancia a fallos ,[INFO.INFO-DC]Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC] ,Escalabilidad ,Elasticité - Abstract
In recent years, applications in domains such as telecommunications, network security or large scale sensor networks showed the limits of the traditional store-then-process paradigm. In this context, Stream Processing Engines emerged as a candidate solution for all these applications demanding for high processing capacity with low processing latency guarantees. With Stream Processing Engines, data streams are not persisted but rather processed on the fly, producing results continuously. Current Stream Processing Engines, either centralized or distributed, do not scale with the input load due to single-node bottlenecks. Moreover, they are based on static configurations that lead to either under or over-provisioning. This Ph.D. thesis discusses StreamCloud, an elastic paralleldistributed stream processing engine that enables for processing of large data stream volumes. Stream- Cloud minimizes the distribution and parallelization overhead introducing novel techniques that split queries into parallel subqueries and allocate them to independent sets of nodes. Moreover, Stream- Cloud elastic and dynamic load balancing protocols enable for effective adjustment of resources depending on the incoming load. Together with the parallelization and elasticity techniques, Stream- Cloud defines a novel fault tolerance protocol that introduces minimal overhead while providing fast recovery. StreamCloud has been fully implemented and evaluated using several real word applications such as fraud detection applications or network analysis applications. The evaluation, conducted using a cluster with more than 300 cores, demonstrates the large scalability, the elasticity and fault tolerance effectiveness of StreamCloud.; En los útimos años, aplicaciones en dominios tales como telecomunicaciones, seguridad de redes y redes de sensores de gran escala se han encontrado con múltiples limitaciones en el paradigma tradicional de bases de datos. En este contexto, los sistemas de procesamiento de flujos de datos han emergido como solución a estas aplicaciones que demandan una alta capacidad de procesamiento con una baja latencia. En los sistemas de procesamiento de flujos de datos, los datos no se persisten y luego se procesan, en su lugar los datos son procesados al vuelo en memoria produciendo resultados de forma continua. Los actuales sistemas de procesamiento de flujos de datos, tanto los centralizados, como los distribuidos, no escalan respecto a la carga de entrada del sistema debido a un cuello de botella producido por la concentración de flujos de datos completos en nodos individuales. Por otra parte, éstos están basados en configuraciones estáticas lo que conducen a un sobre o bajo aprovisionamiento. Esta tesis doctoral presenta StreamCloud, un sistema elástico paralelo-distribuido para el procesamiento de flujos de datos que es capaz de procesar grandes volúmenes de datos. StreamCloud minimiza el coste de distribución y paralelización por medio de una técnica novedosa la cual particiona las queries en subqueries paralelas repartiéndolas en subconjuntos de nodos independientes. Ademas, Stream- Cloud posee protocolos de elasticidad y equilibrado de carga que permiten una optimización de los recursos dependiendo de la carga del sistema. Unidos a los protocolos de paralelización y elasticidad, StreamCloud define un protocolo de tolerancia a fallos que introduce un coste mínimo mientras que proporciona una rápida recuperación. StreamCloud ha sido implementado y evaluado mediante varias aplicaciones del mundo real tales como aplicaciones de detección de fraude o aplicaciones de análisis del tráfico de red. La evaluación ha sido realizada en un cluster con más de 300 núcleos, demostrando la alta escalabilidad y la efectividad tanto de la elasticidad, como de la tolerancia a fallos de StreamCloud.; In recent years...
- Published
- 2022
9. Analyse des déterminants de la demande des biens de première nécessité dans la ville de Kisangani en RDC
- Author
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AHADI MUTUNZI, Adrien, MATATA MAKALAMBA, Patrick, DHEVE DRAKELE, Espérance, AHADI MUTUNZI, Adrien, MATATA MAKALAMBA, Patrick, and DHEVE DRAKELE, Espérance
- Abstract
Ce papier se penche sur la détermination des facteurs influençant la demande des biens de première nécessité (riz, maïs et manioc) et la sensibilité de leur demande à la variation du prix sur le marché de Kisangani en RDC. Outre, le prix et le revenu qui sont des déterminants classiques de la demande, d’autres déterminants clés ont été identifiés et analysés dans cette étude et influencent significativement la demande des produits étudiés. La sensibilité de la demande pour ces trois produits est négative. Cela se traduit par les élasticités prix de ces produits qui sont respectivement de -0,26 pour le maïs, -0,09 pour le riz et -0,12 pour le manioc. Ceci signifie que lorsque les prix de ces produits augmentent de 1%, la demande diminue respectivement de 0,26%, 0,09% et 0,12%.
- Published
- 2022
10. Trade-off mechanism of honey bee sucking and lapping
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Wei, Jiangkun, Brau, Fabian, Damman, Pascal, Draux, Ayrton, Hua, Hoa Ai Béatrice, Wu, Zhigang, Wu, Jianing, Wei, Jiangkun, Brau, Fabian, Damman, Pascal, Draux, Ayrton, Hua, Hoa Ai Béatrice, Wu, Zhigang, and Wu, Jianing
- Abstract
info:eu-repo/semantics/published
- Published
- 2022
11. Tidal deformability of crystallized white dwarfs in full general relativity
- Author
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Perot, Loïc and Perot, Loïc
- Abstract
info:eu-repo/semantics/published
- Published
- 2022
12. Capillary coalescence of two partially immersed slender structures
- Author
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Siefert, Emmanuel, Hua, Hoa Ai Béatrice, Brau, Fabian, Siefert, Emmanuel, Hua, Hoa Ai Béatrice, and Brau, Fabian
- Abstract
We study the onset of coalescence between two slender structures quasi-statically withdrawn from a liquid bath. When partially immersed, they interact with each other through the capillary force induced by their menisci. As they are removed from the bath, their dry length increases and they become easier to bend until the capillary force is strong enough to trigger contact. Surprisingly, the structures snap to contact from a finite distance at a critical dry length. The transition to coalescence is thus subcritical and exhibits a large hysteresis loop between two stable states. An analytical coalescence criterion is derived and agrees well with experimental data for rods and lamellae. This simple elastocapillary model is a first step to better understand the elastocapillary coalescence of slender structures in fluid capture systems., SCOPUS: ar.j, info:eu-repo/semantics/published
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- 2022
13. Etude de l’effet élastocalorique (eC) dans le Caoutchouc Naturel (NR) pour les systèmes de réfrigération solide
- Author
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Haissoune, Hiba and STAR, ABES
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Thermal exchanges ,Strain induced crystallization ,Kinetics of crystallisation ,Matériaux ,Elastomer ,[SPI.MAT] Engineering Sciences [physics]/Materials ,Waxs ,Echange thermique ,Sollicitation cyclique ,Materials ,Elasticité ,Mechanical straining ,WAXS - Wide Angle X-Ray Scattering ,Sollicitation mécanique ,Réfrigération ,Cinétique de cristallisation ,Refrigeration system ,Elastomère ,Elasticity ,Natural rubber ,Caoutchouc naturel ,Thermography ,Cristallisation induite par la déformation ,Elastocaloric effect ,Cyclic loading ,Effet élastocalorique ,Thermographique - Abstract
Natural rubber (NR) is an elastocaloric (eC) material that displays a significant temperature variation under dynamic mechanical loading at high elongations (λ). Its high elastocaloric response and fatigue resistance make it an ideal candidate for the development of robust refrigeration systems. Two phenomena are responsible for its eC performance: orientation/disorientation of macromolecules and crystallization/melting, induced by loading/unloading. In order to better understand the parameters governing the eC response of NR, it was important to first study its crystallization kinetics under deformation (SIC) via thermal, mechanical, and WAXD in-situ measurements. The coupling of these techniques showed that the heat generated mainly by the crystallization delays its own kinetics. Then, in order to evaluate the impact of this SIC on the thermal and mechanical responses of NR under conditions close to those of an eC system, this material was subjected to two types of cyclic solicitations (rectangular/triangular) at 4≤λ≤6. The main difference between them is that under rectangular loading, crystallization occurs mainly after adiabatic elongation while in the triangular case, it occurs during deformation. For f≤0.01Hz, the mechanical hysteresis is three times higher under rectangular loading than under triangular one for the same amount of heat that can be exchanged (Qtotal), consequently the eC efficiency of the material is significantly reduced. For 0.01Hz≤f≤0.5Hz, this heat is certainly lowered under triangular conditions, however, this type of loading is still more advantageous due to its low mechanical losses. Finally, a comparison of the eC performance (Qtotal and coefficient of performance COP) of different polyisoprene samples under triangular deformation shows that synthetic rubber and non-crosslinked NR are less efficient from an eC point of view. The former because its Qtotal is very low and the latter because of its large plastic deformation. The sulfur-crosslinked NR sample, whose active chain density is close to 1.5x10-4mol/cm3, shows the highest eC effect (Qtotal≈11MJ/m3 and COP≈30)., Le caoutchouc naturel (NR) est un matériau élastocalorique (eC) dont la température peut varier significativement sous l’effet d’une sollicitation mécanique dynamique à des élongations (λ) élevées. Son potentiel élastocalorique important et sa résistance à la fatigue en font un candidat idéal pour développer des systèmes de réfrigération solide. Deux phénomènes sont à l'origine de ses performances eC: l’orientation/désorientation des macromolécules et la cristallisation/fusion, induites par l’élongation/rétraction du matériau. Pour mieux comprendre les paramètres qui régissent cette réponse eC du NR, il était primordial d'étudier d’abord sa cinétique de cristallisation sous déformation (SIC) via des mesures thermiques, mécaniques et par WAXD in-situ. Le couplage de ces techniques a montré que la chaleur générée majoritairement par la cristallisation retarde sa propre cinétique. Ensuite, afin d’évaluer l’impact de cette SIC sur les réponses thermiques et mécaniques du NR dans des conditions proches de celles du fonctionnement d’un système eC, ce matériau a subi deux types de sollicitations cycliques (créneaux/triangulaires) à 4≤λ≤6. La principale différence entre ces dernières est qu’en créneau, la cristallisation a lieu majoritairement après la charge adiabatique tandis qu’en triangulaire, elle se fait pendant la déformation. Pour f≤0.01Hz, cette différence de comportement implique l’apparition d’une hystérèse mécanique trois fois plus importante en créneau qu’en triangulaire pour une même quantité de chaleur pouvant être échangée (Qtotale), réduisant ainsi l’efficacité eC du matériau. Pour 0.01Hz≤f≤0.5Hz, cette chaleur est certes plus faible en triangulaire, cependant, cette sollicitation reste plus avantageuse d’un point de vue énergétique grâce à ses faibles pertes mécaniques. Enfin, une comparaison des performances eC (Qtotale et coefficient de performance COP) de différents échantillons de polyisoprène sous déformation triangulaire montre que le NR non-réticulé et le Caoutchouc Synthétique sont moins performants d’un point de vue eC. Le premier, à cause de sa grande déformation rémanente et le deuxième, car son Qtotale est très faible. L’échantillon NR réticulé au soufre avec une densité de chaînes actives proche de 1.5x10-4mol/cm3 présente quant à lui l’effet eC le plus important (Qtotale≈11MJ/m3 et COP≈30).
- Published
- 2022
14. Elasticity of self assembling bio-materials
- Author
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Le Roy, Hugo, Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay, Martin Lenz, and STAR, ABES
- Subjects
[PHYS.PHYS.PHYS-BIO-PH] Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph] ,Auto-assemblage ,[PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph] ,Biophysics ,Biophysique ,Elasticity ,Rhéologie ,[PHYS.COND.CM-SCM] Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft] ,Self-Assembly ,[PHYS.COND.CM-SM] Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech] ,[PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech] ,Rheology ,[PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft] ,Elasticité - Abstract
Self organization is crucial for the wealth of living systems, both at the molecular and cellular level. To correctly achieve their role, a tight control over the shape and structure of the protein, for instance, is required. Any mistake can lead to various diseases like Alzheimer, where proteins aggregate into fibrous structures. On a larger scale, cells need to probe the mechanical response of their environment -the extra cellular matrix- and to adapt their own rigidity to collectively orientate. In this thesis, we are looking at two different models. In the first part, we study protein aggregation beyond the microscopical details. By considering elastic assembling particles, we are able to derive generic laws and understand the persistent formation of fibers. In the second part, we model the dynamical response of a fashionable class of hydrogels for their biocompatibility. Material engineers are now able to synthesize materials with more and more subtle behavior, although understanding certain emergent properties -such as non-exponential relaxation- can be a major challenge. We design a simple model for the dynamical response of hydrogels connected by large multivalent crosslinkers. We are able to account for experimental results, and rationalize their origin., Les systèmes biologiques sont entièrement auto-assemblés, à la fois à l’échelle moléculaire et cellulaire. Pour réussir la forme et la structure de chaque protéine par exemple, doit être précisément contrôlée. La moindre erreur conduit à des maladies telles qu’Alzheimer où des protéines s’agrègent entre elles pour former des structures fibreuses. À une échelle plus large les cellules ont besoin de sonder la réponse mécanique de leur environnement -la matrice extra cellulaire- et d’adapter leur propre rigidité pour être capable de s’orienter collectivement. Dans cette thèse nous étudions deux modèles différents. Dans la première partie, nous étudions l’agrégation de protéines au-delà des détails microscopiques. En considérant l’assemblage de particules élastiques, nous sommes capables de comprendre la formation générique de structures fibreuses. Dans la seconde partie, nous modélisons la réponse dynamique d’une catégorie d’hydrogel qui suscite beaucoup d’intérêt en raison de leur compatibilité biologique. Les ingénieurs en matériaux sont aujourd’hui capables de synthétiser des matériaux aux propriétés surprenantes, néanmoins comprendre l’origine de ces propriétés émergentes peut s’avérer compliqué. Nous modélisons la réponse dynamique des hydrogels connectés par de gros agents réticulants multivalent. Ceci nous permet de reproduire les résultats expérimentaux et d’en comprendre l’origine.
- Published
- 2021
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