25 results
Search Results
2. Viabilité et développement durable.
- Author
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Durand, Marie-Hélène, Martin, Sophie, and Saint-Pierre, Patrick
- Subjects
SUSTAINABLE development ,MATHEMATICAL models ,A priori ,MATHEMATICAL optimization ,INTERGENERATIONAL equity ,MATHEMATICAL inequalities - Abstract
Copyright of Natures Sciences Sociétés is the property of EDP Sciences 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
- 2012
- Full Text
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3. La valse des ensembles. De la mathématique à la logique.
- Author
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MIEVILLE, Denis
- Subjects
LOGIC ,MATHEMATICAL models - Abstract
This paper presents the results of a pertinent meditation of the author concerning the concept of „set" from the mathematical theory and its consequences in the logical theory of classes. After all, one of these consequences draws our attention: semantical antinomies. The starting point of these analyses originates in the famous work of Bertrand Russell and Alfred North Whitehead Principia Mathematica (1910-1913), authors who developed the well known paradox of „the class of the classes which do not include themselves as element" and proposed as solution the known „theory of types". The focus of our paper is the contribution of the Polish logician Stanislav Lesniewski (1886-1939) to the solutioning of the russellian problem of antinomies by distinguishing between mereology, ontology and protothetic. [ABSTRACT FROM AUTHOR]
- Published
- 2011
4. Choix du modèle fréquentiel le plus adéquat à l'estimation des valeurs extrêmes de crues (cas du nord de L'Algérie).
- Author
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Hebal, Aziz and Remini, Boualem
- Subjects
FLOODS ,BAYESIAN analysis ,WATERSHEDS ,DISTRIBUTION (Probability theory) ,MATHEMATICAL models ,ESTIMATION theory - Abstract
Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing 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
- 2011
- Full Text
- View/download PDF
5. LA CONVERSION DE PARCELLES VITICOLES EN USAGE RÉSIDENTIEL: LE CAS DE L'AIRE URBAINE DE BORDEAUX.
- Author
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Pérès, Stéphanie and Gaussier, Nathalie
- Subjects
SUBURBS ,LAND use ,VINEYARDS ,MATHEMATICAL models ,RURAL development - Abstract
Copyright of Canadian Journal of Regional Science / Revue Canadienne des Sciences Régionales is the property of Canadian Regional Science Association 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
- 2010
6. Programmes agri-environnementaux en présence d'effets de seuils.
- Author
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Dupraz, Pierre, LaTouche, Karine, and Turpin, Nadine
- Subjects
AGRICULTURE ,ECOLOGY ,FARMERS ,COST effectiveness ,INDUSTRIAL costs ,ENVIRONMENTAL policy ,ENVIRONMENTAL economics ,ECONOMIC models ,MATHEMATICAL models ,ECONOMIES of scale - Abstract
Copyright of Cahiers d'Economie et Sociologie Rurales is the property of Institut National de la Recherche Agronomique (INRA) 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
- 2007
7. Characterization and modelling of IR sensors
- Author
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Castelein, Pierre
- Subjects
- *
DETECTORS , *INFRARED detectors , *PHYSICAL measurements , *MATHEMATICAL models of human behavior , *MATHEMATICAL models - Abstract
The objective of this paper is to describe the first behavioural models of cooled (based on HgCdTe photodetectors) infrared sensors which were designed at CEA-LETI/SLIR. In this way, the interest of such an approach in the evaluation and improvement of optronic systems will be shown. The paper first presents the modelling approach (architecture of the models, choice of parameters, tools for modelling and calibration,
… ). Then models are compared to measurements on real components in order to verify the efficiency of the modelling approach. To cite this article: P. Castelein, C. R. Physique 4 (2003). [Copyright &y& Elsevier]- Published
- 2003
- Full Text
- View/download PDF
8. Influence d'un écoulement horizontal sur les propriétés linéaires de la convection de fluides viscoélastiques en milieux poreux
- Author
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Hirata, Sílvia C. and Najib Ouarzazi, Mohamed
- Subjects
- *
VISCOELASTICITY , *CONTINUUM mechanics , *POLYMERIC composites , *POROUS materials , *MATHEMATICAL models , *DIMENSIONLESS numbers , *STABILITY (Mechanics) - Abstract
Abstract: This paper investigates the instability of a viscoelastic fluid in a saturated porous medium heated from below and subjected to an horizontal through-flow. The Oldroyd-B constitutive equation is used to describe the viscoelastic behavior of diluted polymeric solutions. In the absence of the horizontal flow, the onset of convection can be characterized either by stationary or oscillatory instabilities. A temporal stability analysis is carried out in order to study the combined influence of the viscoelastic properties of the fluid and the main flow on the linear characteristics of these two types of instabilities. It is shown that the presence of the through-flow has a destabilizing effect and that it favors the emergence of mobile transverse rolls (R.T.), among an infinity of three-dimensional unstable modes. The thresholds for the appearance of these R.T., as well as their wavelengths and frequencies, are determined as functions of the dimensionless parameters of the problem. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
9. La conception d'un programme motivationnel destiné aux cycles supérieurs en formation à distance.
- Author
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Racette, Nicole
- Subjects
DISTANCE education ,MOTIVATION (Psychology) ,STUDENT attitudes ,LEARNING ,EDUCATION ,MATHEMATICAL models - Abstract
Copyright of Journal of Distance Education is the property of Canadian Network for Innovation in Education 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
- 2009
10. Extension spatiale de la salinisation des ressources en eau et modèle conceptuel des sources salées dans la plaine des Triffa (Maroc nord-oriental)
- Author
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Boughriba, Mimoun, Melloul, Abderrahmane, Zarhloule, Yassine, and Ouardi, Abdelillah
- Subjects
- *
SALINIZATION , *DROUGHTS , *PLAINS , *WATER quality , *GROUNDWATER , *WATER supply , *MATHEMATICAL models , *BRACKISH waters - Abstract
Abstract: The succession of drought years and excessive abstraction in the plain of Triffa caused deterioration in water quality and endangers future exploitation of groundwater resources. A combination of geophysical surveys, including electrical resistivity and hydrochemical data has been used to identify the geographical extension of salinization and identify its origin. Electrical conductivity measurements are used to show the history of salinization in space and time. In this paper, a first conceptual model of the brackish springs has been established. To cite this article: M. Boughriba et al., C. R. Geoscience 338 (2006). [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
11. Effets de la vitesse d'écoulement sur le transport et la cinétique de dépôt de particules en suspension en milieu poreux saturé
- Author
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Benamar, Ahmed, Wang, HuaQing, Ahfir, Nasre-dine, Alem, Abdellah, Masséi, Nicolas, and Dupont, Jean-Paul
- Subjects
- *
POROUS materials , *SEDIMENTATION & deposition , *CHROMATOGRAPHIC analysis , *GEOMORPHOLOGICAL tracers , *MATHEMATICAL models - Abstract
Abstract: We study in this paper the transport and deposition of suspended particles in saturated porous media. Some chromatographic short-pulse tests were performed in a laboratory column with a tracer and two types of suspended particles. A mathematical model was used to determine the hydrodispersive parameters and deposition rates from the breakthrough curves. The results show that the fitted parameters obtained vary with the flow rate and the characteristics of the suspended particles. We also observe, at high flow rates, that particles have a migration velocity higher than that of the conservative tracer. To cite this article: A. Benamar et al., C. R. Geoscience 337 (2005). [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
12. Single Functional Index Model
- Author
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Ferraty, Frédéric, Peuch, Agnès, and Vieu, Philippe
- Subjects
- *
GEOMETRY , *MATHEMATICS , *MATHEMATICAL models - Abstract
This paper concerns a generalization of the “Single Index Model” when the explanatory variable is valued in an infinite dimensional space. Such model will be called the “Single Functional Index Model”. The main contribution of this study is to propose a functional framework which includes the classical vectorial case. Pointwise asymptotic properties are stated under less restrictive conditions on the law of the explanatory variable than what it is usually assumed in the vectorial case. To cite this article: F. Ferraty et al., C. R. Acad. Sci. Paris, Ser. I 336 (2003). [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
13. Lie-admissible operads
- Author
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Remm, Elisabeth
- Subjects
- *
LIE-admissible algebras , *ASSOCIATIVE algebras , *MATHEMATICAL models - Abstract
The aim of this paper is to present remarkable classes of Lie-admissible algebras containing in particular the associative algebras, the Vinberg and pre-Lie algebras. We determine the associated operads and their dual operads. To cite this article: E. Remm, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 1047–1050. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
14. The mathematician, the Surrealist, and the poet are of imagination all compact: Man Ray’s Shakespearean Equations
- Author
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Anne-Kathrin Marquardt
- Subjects
Man Ray ,mathematical models ,painting ,King Lear ,Hamlet ,Shakespeare (William) ,Visual arts ,N1-9211 - Abstract
Man Ray’s series of paintings entitled Shakespearean Equations remains largely unknown even today, despite the artist’s fame. Perhaps that is partly because, like many Surrealist works, it so stubbornly resists interpretation; it is difficult to even grasp what one is looking at. The paintings depict mathematical models and their only Shakespearean characteristics are their titles, taken directly from Shakespeare’s canon. Nevertheless, I argue that a fruitful analysis is possible by understanding the pictures in relation to Shakespeare’s texts, the reception of Shakespeare in the twentieth century, and the reception of non-Euclidean geometry in artistic circles at the time. My study thus hinges on an assessment of the context in which Man Ray produced these works. But it also takes a closer look at two paintings in the series, uncovering the textual and pictorial sources they reference, parsing the layers of meaning which are thus built up. This paper does not set itself the impossible task of producing a definitive interpretation, which would, among other things, be contrary to the Surrealist spirit. I rather hope to explore what this particular act of appropriation uncovers about the reception of Shakespeare and mathematics.
- Published
- 2019
- Full Text
- View/download PDF
15. Matematyka w teologii, teologia w matematyce
- Author
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Stanisław Krajewski
- Subjects
philosophy of mathematics ,God’s point of view ,theological metaphors ,religious inspirations ,mathematical models ,Philosophy (General) ,B1-5802 - Abstract
Mathematicians use theological metaphors when they talk in the kitchen of mathematics. How essential is this talk? Have theological considerations and religious concepts influenced mathematics? Can mathematical models illuminate theology? Some authors have given positive answers to these questions, but they do not seem final. It is unclear how religious views influenced the work of those mathematicians who were also theologians. Religious background of some mathematical concepts could have been inessential. Mathematical models in theology have no predictive value. It is, however, important to continue the recently initiated search for the mutual influences of mathematics and theology. (In addition to the references listed at the end of this paper, one can also consult the volume “Theology in Mathematics?” ed. by Stanisław Krajewski and Kazimierz Trzęsicki, Studies in Logic, Grammar and Rhetoric 44 (57), 2016.)
- Published
- 2016
16. Non-isothermal moisture balance equation in porous media: a review of mathematical formulations in Building Physics
- Author
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Dubois, S., Evrard, A., and Lebeau, F.
- Subjects
HAM modeling ,porous media ,capillarity ,sorption ,diffusivity ,isosteric heat ,mathematical models ,moisture content ,Biotechnology ,TP248.13-248.65 ,Environmental sciences ,GE1-350 - Abstract
Understanding heat and mass transfers in porous materials is crucial in many areas of scientific research. Mathematical models have constantly evolved, their differences lying mainly in the choice of the driving potentials used to describe moisture flows, as well as in the complexity of characterizing the physical phenomena involved. Models developed in the field of Building Physics (HAM models) are used to describe the behavior of envelope parts and assess their impact on user comfort and energy performance. The water balance equation can be described in many ways; it is a function of the boundary conditions considered and the fact they induce high or low water content in the porous materials used. This paper gives an overview of various formulations for this equation that are found in the Building Physics literature. It focuses first on the physically based formulation of moisture balance, drawing on the Representative Elementary Volume (REV) concept, coupled with thermodynamic flow rates description. This is then reformulated in line with various main moisture state variables offering a wide variety of expressions that are compared with available models. This approach provides access to all secondary transport coefficients associated with the process of mathematical transformation. Particular emphasis is placed on the moisture storage function choice and its impact on the final mathematical formulations.
- Published
- 2014
17. Approche experimentale du comportement d'une plaque composite sous effet d'un choc perforant
- Author
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Paris, P, Genin, D, and Hamelin, P
- Subjects
Mathematical models ,Essai de choc ,Impact ,Simulation numérique ,Ship technology ,Collisions ,Composite materials ,Plaque composite ,Réponse dynamique ,Simulation ,Materials testing ,Numerical analysis - Abstract
Our purpose in this paper is to study the behaviour of composite materials reinforced by glass satin weave 8 fabric under the impact of a projectile. The first part of this paper deals with experimental tests carried out using a servo-hydraulic machine. The hydraulic ram can be programmed to impact the specimen at any desired velocity between a few tenths of a millimetre per minute and 20 m/s. In the second part, these experimental results are compared with the numerical results of bidimensional finite difference code AUTODYN. This program allows the numerical simulation of the penetration of composite plates by projectiles., Cette étude est consacrée au comportement au choc de plaques en matériaux composites renforcés par un tissu de verre satin de 8. La première partie traite des résultats expérimentaux effectués en utilisant une machine servo-hydraulique. Le vérin hydraulique peut être programmé pour perforer une éprouvette à une vitesse choisie entre quelques dixièmes de millimètres par minute et 20 m/s. Dans la seconde partie, ces résultats expérimentaux sont comparés avec les résultats numériques d'un code de calcul utilisant les différences finies tridimensionnel AUTODYN. Ce programme permet la simulation numérique de la pénétration de plaques de composite par des projectiles.
- Published
- 1992
18. Un cadre de référence intégrateur pour soutenir la fonction évaluation de l'infirmière pivot en oncologie du Québec.
- Author
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Fournier, Brigitte, Simard, Sébastien, Veillette, Anne-Marie, and Fillion, Lise
- Subjects
ONCOLOGY nursing ,CANCER patients ,CONTINUUM of care ,MATHEMATICAL models ,RESEARCH methodology ,NEEDS assessment ,NURSES ,NURSING assessment ,PATIENT education ,QUALITATIVE research ,THEORY ,OCCUPATIONAL roles ,SOCIAL support ,PATIENT-centered care - Abstract
Copyright of Canadian Oncology Nursing Journal is the property of Pappin Communications 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
- 2015
- Full Text
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19. Intentions de fécondité et obstacles à leur réalisation en France et en Italie.
- Author
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Régnier-Loilier, Arnaud and Vignoli, Daniele
- Subjects
HUMAN fertility ,GENERATIONS ,GENDER ,COUPLES ,SOCIOECONOMIC factors ,INTENTION ,CHILDBIRTH ,MATHEMATICAL models - Abstract
Copyright of Population (00324663) is the property of Institut National d'Etudes Demographiques 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
- 2011
20. Minimisation des surcoûts dans un contexte hors délai : cas des projets de construction dans les pays en développement.
- Author
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Louzolo-Kimbembé, Paul, Pettang, Chrispin, and Tatiétsé, Thomas Tamo
- Subjects
CONSTRUCTION costs ,COST effectiveness ,CONSTRUCTION industry ,INVESTORS ,MATHEMATICAL models ,CONSTRUCTION spending ,DEVELOPING countries - Abstract
Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing 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
- 2007
- Full Text
- View/download PDF
21. Application des modèles mathématiques pour l’optimisation de l’énergie dans un système PV
- Author
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S. Semaoui, Seddik Bacha, Amar Hadj Arab, Centre de Développement des Energies Renouvelables, B.P, 62, Route de l’Observatoire, Bouzaréah, Alger, Laboratoire de Génie Electrique de Grenoble (G2ELab), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])
- Subjects
Physics ,Optimization ,Mathematical Models ,Système PV ,[SPI.NRJ]Engineering Sciences [physics]/Electric power ,Optimisation ,General Medicine ,7. Clean energy ,Humanities ,Modélisation mathématique ,Simulation ,PV system - Abstract
This paper proposes an approach used to optimize the energy for a stand-alone photovoltaic (PV) system in isolated regions. The intended objective is house energy comfort. The aim is to present the impact of flow energy of housing on the system reliability. The operation of stand-alone PV system is represented by a simulation program. This later describes the principle of energy equilibrium among diverse sub-systems, using different mathematical models of different parts of renewable energy system. The recommended models were implemented via Matlab-Simulink software with real input data. The reliability is achieved by reducing the loss power supply probability criteria, with improvement of the battery life cycle during the operating years of the PV system., Cet article propose une approche basée sur des modèles mathématiques validés, pour l’optimisation de l’énergie dans un système photovoltaïque (PV) autonome destiné à l’électrification d’un habitat dans une région isolée. L’objectif attendu est le confort énergétique de l’habitat. Le but du travail est de montrer à travers la modélisation mathématique l’impact du profil dynamique de la consommation énergétique sur la fiabilité du système PV. Le fonctionnement de ce dernier est représenté par un programme de simulation sous Simulink, qui décrit le principe de l'équilibre énergétique entre les sous-systèmes, en utilisant des modèles mathématiques validés avec des données d’entrées réelles. Les résultats obtenus ont montrés une bonne fiabilité des modèles utilisés, pour prévoir le fonctionnement optimal du système photovoltaïque.
- Published
- 2019
22. Size effect in polymers nano-reinforced : multiscale characterization and modelization
- Author
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Blivi, Adoté Sitou and STAR, ABES
- Subjects
Mathematical models ,Propriétés thermiques ,Thermal properties ,Polymers ,Mechanical testing ,Mechanical properties ,Composite materials ,Multi-scale analysis ,Elasticity ,[SPI.MECA.MEMA] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph] ,Nanocomposites ,Effet de taille ,Propriétés mécaniques ,Nanoparticles ,Micromechanics ,Size effect ,Caractérisation multi-échelles ,[SPI.MECA.GEME] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanical engineering [physics.class-ph] ,Microstructure ,Nano-renforts - Abstract
The work presented in this paper aims to highlight and to understand the size effect of nano-reinforcements on nanocomposite properties With an experimental approach. Nanocomposites of PMMA and silica particles With different sizes (15nm, 25nm, 60nm, 150nm and 500nm) and volume fractions (20/0, 4 0/0 and 60/0) were manufactured. Multiscale analysis (MET and DRX-WAXS) have shown that the characteristic parameters of the microstructure of nanocomposites vary With the size of the nanoparticles. Indeed, the decrease in the size of nanoparticles at a given volume fraction implies a decrease of the intermolecular distance. This decrease has induced a densification of the matrix and a decrease of the matrix chain mobility. Mechanical tests (tensile, DMA) have shown that the young (E) and the conservation (E') moduli of the nanocomposites increase With the decrease in the size of the nanoparticles With a constant volume fraction. And the increase of E l is kept when temperature growing. An increase in glass transition (Tg) and degradation temperature (Td) was also observed With the DSC, DMA and ATG tests. Experimental elastic properties of the nanocomposites were used to assess the relevance of size effect micromechanical models, particularly the Hashin-Shtrikman bounds With interface effects proposed by Brisard. The modeling has shown that to reproduce the experimental elastic moduli of nanocomposites, the elastic coefficients of the interface must be dependents on particle sizes. And the state of dispersion of particles must be taken into account., Le travail présenté dans ce document vise à mettre en évidence et à comprendre l'effet de la taille nanométrique des renforts sur les propriétés des nanocomposites avec une approche expérimentale. Des nanocomposites de PMMA et particules de silice (15nm, 25nm, 60nm, 150nm et 500nm) de fractions volumiques 2 0/0, 40/0 et 6 0/0 ont été fabriqués. Des analyses multi-échelles (MET et DRX-WAXS) ont montré que les paramètres caractéristiques de la microstructure des nanocomposites varient avec la taille des nanoparticules. En effet, la diminution de la taille des nanoparticules à fraction volumique constante a entrainé une diminution de la distance intermoléculaire. Cette diminution a induit une densification de la matrice et une réduction de la mobilité des chaînes de la matrice. Des essais mécaniques (traction, DMA) ont montré que les modules de Young (E) et de conservation (E') des nanocomposites augmentent avec la diminution de la taille des nanoparticules à fraction volumique constante. Et que l'augmentation de E' est conservée avec l'augmentation de la température. Une augmentation des températures de transition vitreuse (Tg) et de dégradation (Td) a également été observée avec les essais DSC, DMA et ATG. Le modèle de la borne inférieure d'Hashin-Shtrikman étendue aux nanocomposites à renforts sphériques proposé par Brisard a été utilisé. La modélisation des modules élastiques des nanocomposites a montré que pour reproduire les données expérimentales, il faut que d'une part que les modules surfaciques caractérisant l'interface soient dépendants de la taille des nanoparticules. Et d'autre part, tenir compte de l'état de dispersion des nanoparticules.
- Published
- 2018
23. Une théorie de plaque sandwich
- Author
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Mace, M
- Subjects
Condensed Matter::Soft Condensed Matter ,Physics::Fluid Dynamics ,Mathematical models ,Shear strength ,Cisaillement ,Film mince ,Ship technology ,Composite materials ,Calculs de structures composites ,Théorie de plaque sandwich ,Strain - Abstract
The objective of this paper is to present a new two-dimensional plate theory inside which a very thin layer is sandwiched. Based upon a prescribed displacement field and a shear stress field fulfilling continuity conditions at the interfaces, this model takes into account the shearing strain due to the high rigidity ratio between the thick skins and the thin film. It is also shown how the present theory was assessed when calculating a rectangular sandwich plate for which Pagano proposed an "exact" three-dimensional solution., L'objet de cet article est de présenter une théorie tridimensionnelle de plaque sandwich dans laquelle est inséré un film mince. Cette théorie, valable en statique et en dynamique, est basée sur des hypothèses portant sur les champs de déplacements et de contraintes. Ce modèle prend en compte le phénomène de cisaillement transversal dû au contraste de rigidités entre les peaux épaisses et le film. Le but de cet article est de montrer également comment cette théorie a été validée en statique dans le cas d'un calcul de plaque rectangulaire appuyée, pour laquelle une solution "exacte" tridimensionnelle a été proposée par Pagano.
- Published
- 1992
24. Modelisation numerique du flambage de panneaux sandwich raidis
- Author
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Batoz, J and Quesnel, T
- Subjects
Condensed Matter::Soft Condensed Matter ,Flambage ,Structure sandwich ,Mathematical models ,Plaque coque ,Ship technology ,Composite materials ,Modelling ,Eléments finis ,Numerical analysis ,Matériau composite - Abstract
This paper presents a numerical method for the buckling analysis of stiffened sandwich panels for ship building with composite materials. The formulation of a multi-layered quadrilateral finite element of a plane shell including transverse shear effects is presented. Some classical tests allow the performance of this element to be evaluated for composite plates. Then an explanation is given for a method used for analyzing the buckling of panels., Cet article présente une méthode numérique d'analyse du flambage de panneaux sandwichs raidis pour la construction navale en composites. La formulation d'un élément fini quadrilatère de coque plane prenant en compte le cisaillement transverse est présentée dans une version multicouche. Quelques tests classiques permettent d'évaluer la performance de cet élément pour des plaques composites. La méthode qui sera utilisée pour l'analyse de flambage, est ensuite exposée.
- Published
- 1992
25. Dynamique des populations marines exploitées. Tome 1. Concepts et modèles
- Author
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Laurec, Alain and Le Guen, Jean-claude
- Subjects
Mathematical models ,Fishery resources ,Conservation de la ressource ,Population dynamics ,Dynamique des populations ,Gestion de stock ,Stock assessment ,Pêche ,Resource conservation ,Modèle mathématique - Abstract
This book constitutes the first of a series of three volumes, the purpose of which is to cover the principal methods used in fish population dynamics. It is devoted to the definition of the main concepts, ami the presentation of the usual mathematical models. The second volume will deal with the fitting of the models, and the estimation of parameters. The third will be devoted to sampling problems. These volumes will be recollections of communications presented during ad hoc seminars, hold in Brest (GSG/COB) in 1980 and 1981. The first part deals with the basic concepts related to the two components whose relationship is being described by the population dynamics, namely the fish stock, to its relations with biological populations, and to the partition of catchabtiity into its components (vulnerability, availability...). The second chapter of this part is devoted to the quantification of exploitation. This leads to a discussion of nominal and effective fishing effort and fishing intensity. A brief review of the use of catch per unit of effort as an index of abundance is followed by a discussion of the concept of fishing power. The second part starts with some general remarks on mathematical modelling (chapter III), then comes to the two classical categories of models : global (surplus production) models (chapter IV), and structural models (chapter V). Chapter IV is mainly a review, based upon the SCHAEFER and PELLATOMLINSON models. Some less classical formulas from the recent literature are also introduced. Attention is paid to the underlying hypotheses and to the limitation of such models. The reader is finally referred to papers presenting the developments that could make it possible to overcome some of these limitations. Chapter V is based upon the classical BEVERTON and HOLT and RlCKER models, and the yield per recruit concepts. This field is however inlarged. Other commonly used variants of structural models are presented with an effort being made to clarify the real differences between all these variants. Special attention is also paid to so-called regenerative models and to the use of spawing-biomass or fecundity per recruit, which are likely to become commonly used in the coming years. In all cases, special attention is paid to the presentation of the basic formulas, that the reader might have to use if faced with a practical problem. Finally, a discussion of the underlying hypotheses takes place, before a brief review of the main developments, where the reader is referred to the appropriate literature., Ce livre constitue le premier volet d'un tryptique destiné à effectuer une revue des méthodes essentielles en dynamique des populations marines exploitées. Il est consacré à la définition des concepts de base, à la présentation des modèles courants. Dans la discussion des concepts, ce volume s'attache à clarifier les notions relatives aux deux parties dont les relations font l'objet de la dynamique des populations exploitées : le stock et la flottille de pêche. Ceci amène notamment à préciser la définition d'un stock, sa relation avec la notion de population biologique, à analyser les problèmes de définition de la capturabilité. Les concepts d'intensité, d'effort, de puissance de pêche, une analyse des relations entre abondance et capture par unité d'effort sont ensuite présentés. Après une brève réflexion générale sur la modélisation, la deuxième partie de cet ouvrage présente les modèles eux-mêmes, en abordant successivement les modèles dits globaux et structuraux. Un effort est fait pour couvrir non seulement les versions les plus anciennes, mais aussi les variantes récentes, pour détailler les relations entre ces différentes variantes, offrir un formulaire de base, enfin, discuter les hypothèses majeures et les prolongements souhaitables ou en cours.
- Published
- 1981
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