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Letteratura scientifica selezionata sul tema "Transport nonlocal"

Autore: Grafiati

Pubblicato: 26 ottobre 2024

Ultima modifica: 12 luglio 2025

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Articoli di riviste sul tema "Transport nonlocal"

Shin, Hyeyum Hailey, and Song-You Hong. "Representation of the Subgrid-Scale Turbulent Transport in Convective Boundary Layers at Gray-Zone Resolutions." Monthly Weather Review 143, no. 1 (2015): 250–71. http://dx.doi.org/10.1175/mwr-d-14-00116.1.

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Abstract Parameterization of the unresolved vertical transport in the planetary boundary layer (PBL) is one of the key physics algorithms in atmospheric models. This study attempts to represent the subgrid-scale (SGS) turbulent transport in convective boundary layers (CBLs) at gray-zone resolutions by investigating the effects of grid-size dependency in the vertical heat transport parameterization for CBL simulations. The SGS transport profile is parameterized based on the 2013 conceptual derivation by Shin and Hong. First, nonlocal transport via strong updrafts and local transport via the remaining small-scale eddies are separately calculated. Second, the SGS nonlocal transport is formulated by multiplying a grid-size dependency function with the total nonlocal transport profile fit to the large-eddy simulation (LES) output. Finally, the SGS local transport is formulated by multiplying a grid-size dependency function with the total local transport profile, which is calculated using an eddy-diffusivity formula. The new algorithm is evaluated against the LES output and compared with a conventional nonlocal PBL parameterization. For ideal CBL cases, by considering the scale dependency in the parameterized vertical heat transport, improvements over the conventional nonlocal K-profile model appear in mean profiles, resolved and SGS vertical transport profiles with their grid-size dependency, and the energy spectrum. Real-case simulations for convective rolls show that the simulated roll structures are more robust with stronger intensity when the new algorithm is used.

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Li, Zhipeng, Hongwu Tang, Saiyu Yuan, Huiming Zhang, Lingzhong Kong, and HongGuang Sun. "Modeling Long-Distance Forward and Backward Diffusion Processes in Tracer Transport Using the Fractional Laplacian on Bounded Domains." Fractal and Fractional 7, no. 11 (2023): 823. http://dx.doi.org/10.3390/fractalfract7110823.

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Recent studies have emphasized the importance of the long-distance diffusion model in characterizing tracer transport occurring within both subsurface and surface environments, particularly in heterogeneous systems. Long-distance diffusion, often referred to as nonlocal diffusion, signifies that tracer particles may experience a considerably long distance in either the forward or backward direction along preferential channels during the transport. The classical advection–diffusion (ADE) model has been widely used to describe tracer transport; however, they often fall short in capturing the intricacies of nonlocal diffusion processes. The fractional operator has gained recognition among hydrologists due to its potential to capture distinct mechanisms of transport and storage for tracer particles exhibiting nonlocal dynamics. However, the hypersingularity of the fractional Laplacian operator presents considerable difficulties in its numerical approximation in bounded domains. This study focuses on the development and application of the fractional Laplacian-based model to characterize nonlocal tracer transport behavior, specifically considering both forward and backward diffusion processes on bounded domains. The Riesz fractional Laplacian provides a mathematical framework for describing tracer diffusion processes on a bounded domain, and a novel finite difference method (FDM) is introduced as an effective numerical solver for addressing the fractional Laplacian-based model. Applications reveal that the fractional Laplacian-based model can effectively capture the observed nonlocal tracer transport behavior in a heterogeneous system, and nonlocal tracer transport exhibits dynamic characteristics, influenced by the evolving heterogeneity of the media at various temporal scales.

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Tzou, D. Y. "Nonlocal behavior in phonon transport." International Journal of Heat and Mass Transfer 54, no. 1-3 (2011): 475–81. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2010.09.022.

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Li, Dong, and Jose Rodrigo. "Remarks on a nonlocal transport." Advances in Mathematics 374 (November 2020): 107345. http://dx.doi.org/10.1016/j.aim.2020.107345.

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Del Sorbo, D., J. L. Feugeas, Ph Nicolaï, M. Olazabal-Loumé, B. Dubroca, and V. Tikhonchuk. "Extension of a reduced entropic model of electron transport to magnetized nonlocal regimes of high-energy-density plasmas." Laser and Particle Beams 34, no. 3 (2016): 412–25. http://dx.doi.org/10.1017/s0263034616000252.

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AbstractLaser-produced high-energy-density plasmas may contain strong magnetic fields that affect the energy transport, which can be nonlocal. Models which describe the magnetized nonlocal transport are formally complicated and based on many approximations. This paper presents a more straightforward approach to the description of the electron transport in this regime, based on the extension of a reduced entropic model. The calculated magnetized heat fluxes are compared with the known asymptotic limits and applied for studying of a magnetized nonlocal plasma thermalization.

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Shin, Hyeyum Hailey, and Song-You Hong. "Analysis of Resolved and Parameterized Vertical Transports in Convective Boundary Layers at Gray-Zone Resolutions." Journal of the Atmospheric Sciences 70, no. 10 (2013): 3248–61. http://dx.doi.org/10.1175/jas-d-12-0290.1.

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Abstract The gray zone of a physical process in numerical models is defined as the range of model resolution in which the process is partly resolved by model dynamics and partly parameterized. In this study, the authors examine the grid-size dependencies of resolved and parameterized vertical transports in convective boundary layers (CBLs) for horizontal grid scales including the gray zone. To assess how stability alters the dependencies on grid size, four CBLs with different surface heating and geostrophic winds are considered. For this purpose, reference data for grid-scale (GS) and subgrid-scale (SGS) fields are constructed for 50–4000-m mesh sizes by filtering 25-m large-eddy simulation (LES) data. As relative importance of shear increases, the ratio of resolved turbulent kinetic energy increases for a given grid spacing. Vertical transports of potential temperature, momentum, and a bottom-up diffusion passive scalar behave in a similar fashion. The effects of stability are related to the horizontal scale of coherent large-eddy structures that change in the different stability. The subgrid-scale vertical transport of heat and the bottom-up scalar are divided into a nonlocal mixing owing to the coherent structures and remaining local mixing. The separate treatment of the nonlocal and local transports shows that the grid-size dependency of the SGS nonlocal flux and its sensitivity to stability predominantly determine the dependency of total (nonlocal plus local) SGS transport.

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Silva, S. S. A., J. C. Santos, J. Büchner, and M. V. Alves. "Nonlocal heat flux effects on temperature evolution of the solar atmosphere." Astronomy & Astrophysics 615 (July 2018): A32. http://dx.doi.org/10.1051/0004-6361/201730580.

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Context. Heat flux is one of the main energy transport mechanisms in the weakly collisional plasma of the solar corona. There, rare binary collisions let hot electrons travel over long distances and influence other regions along magnetic field lines. Thus, the fully collisional heat flux models might not describe transport well enough since they consider only the local contribution of electrons. The heat flux in weakly collisional plasmas at high temperatures with large mean free paths has to consider the nonlocality of the energy transport in the frame of nonlocal models in order to treat energy balance in the solar atmosphere properly. Aims. We investigate the impact of nonlocal heat flux on the thermal evolution and dynamics of the solar atmosphere by implementing a nonlocal heat flux model in a 3D magnetohydrodynamic simulation of the solar corona. Methods. We simulate the evolution of solar coronal plasma and magnetic fields considering both a local collision dominated and a nonlocal heat flux model. The initial magnetic field is obtained by a potential extrapolation of the observed line-of-sight magnetic field of AR11226. The system is perturbed by moving the plasma at the photosphere. We compared the simulated evolution of the solar atmosphere in its dependence on the heat flux model. Results. The main differences for the average temperature profiles were found in the upper chromosphere/transition region. In the nonlocal heat transport model case, thermal energy is transported more efficiently to the upper chromosphere and lower transition region and leads to an earlier heating of the lower atmosphere. As a consequence, the structure of the solar atmosphere is affected with the nonlocal simulations producing on average a smoother temperature profile and the transition region placed about 500 km higher. Using a nonlocal heat flux also leads to two times higher temperatures in some of the regions in the lower corona. Conclusions. The results of our 3D MHD simulations considering nonlocal heat transport supports the previous results of simpler 1D two-fluid simulations. They demonstrated that it is important to consider a nonlocal formulation for the heat flux when there is a strong energy deposit, like the one observed during flares, in the solar corona.

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Ghannam, Khaled, Tomer Duman, Gabriel Katul, and Marcelo Chamecki. "GRADIENT-DIFFUSION CLOSURE AND THE EJECTION-SWEEP CYCLE IN CONVECTIVE BOUNDARY LAYERS." Ciência e Natura 38 (July 20, 2016): 552. http://dx.doi.org/10.5902/2179460x21576.

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The inadequacy of conventional gradient-diffusion closure in modeling turbulent heat flux within the convective atmospheric boundary-layer is often alleviated by accounting for nonlocal transport. Such nonlocal effects are a manifestation of the inherent asymmetry in vertical transport in the convective boundary layer, which is in turn associated with third-order moments (skewness and fluxes of fluxes). In this work, the role of these third-order moments in second-order turbulence closure of the sensible heat flux is examined with the goal of reconciling the models to various closure assumptions. Surface layer similarity theory and mixed-layer parametrizations are used here, complemented by LES results when needed. The turbulent heat flux with various closure assumptions of the flux transport term is solved, including both local and nonlocal approaches. We connect to ejection-sweep cycles in the flow field using the GramCharlier cumulant expansion of the joint probability distribution of vertical velocity and potential temperature. In this nonlocal closure, the transport asymmetry models that include the vertical velocity skewness as a correction term to H originate from ejection-sweep events. Vertical inhomogeneity results in a modified-skewness correction to the nonlocal contribution to the heat flux associated with the relative intensity of ejections and sweeps.

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del-Castillo-Negrete, D. "Fractional diffusion models of nonlocal transport." Physics of Plasmas 13, no. 8 (2006): 082308. http://dx.doi.org/10.1063/1.2336114.

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Bychenkov, V. Yu, J. P. Matte, and T. W. Johnston. "Nonlocal electron transport in spherical plasmas." Physics of Plasmas 3, no. 4 (1996): 1280–83. http://dx.doi.org/10.1063/1.871752.

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Più fonti

Tesi sul tema "Transport nonlocal"

Morales-Casique, Eric. "Nonlocal and localized analyses of nonreactive solute transport in bounded randomly heterogeneous porous media." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280728.

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Solute transport in randomly heterogeneous media is described by stochastic transport equations that are typically solved by Monte Carlo simulation. A promising alternative is to solve a corresponding system of statistical moment equations directly. The moment equations are generally integro-differential and include nonlocal parameters depending on more than one point in space-time [Neuman, 1993; Zhang and Neuman, 1996; Guadagnini and Neuman, 2001]. We present recursive approximations, and a numerical algorithm, that allow computing lead ensemble moments of non-reactive solute transport in bounded, randomly heterogeneous media. Our recursive equations are formally valid for mildly heterogeneous aquifers with σ²ᵧ < 1, where σ²ᵧ is a measure of log-hydraulic conductivity variance, or well-conditioned highly heterogeneous aquifers. Our algorithm utilizes a finite element Laplace transform method (FELT) valid for steady state velocity fields. We solved the recursive moment equations up to second order in σᵧ. We also present an iterative improvement of the recursive equations which allows reaching a solution of order higher than two in σᵧ but does not reach third order accuracy because we do not include third order moments in the computations. Computational results in two spatial dimensions conditioned on synthetic measurements of K , hydraulic conductivity, compare well with Monte Carlo results for σ²ᵧ and Peclet number (in terms of the integral scale of K) as high as 0.3 and 100 respectively for the iterative approach. As these parameters increase, the quality of our iterative moment solution deteriorates. Without conditioning the quality of the solution deteriorates more rapidly as dimensionless time increases. The recursive solution without iteration is much less accurate and deteriorates more rapidly as σ²ᵧ , Peclet number, and/or dimensionless time increase. We infer that this loss in accuracy is due to higher order moments which become important as σ²ᵧ , dimensionless time, and/or Pe increase. We also evaluate a space-localized moment equation and show that the quality of its solution is of inferior accuracy than the iterative solution. In terms of computational efficiency, the recursive and iterative methods require less CPU time than Monte Carlo transport simulations using the same numerical solution method (FELT) and without parallelization.

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Toy, Jonathan Andrew. "A Nonlocal Model for the Segregation of Axonal Microtubules and Neurofilaments in Neurodegenerative Diseases." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461080485.

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Del, Sorbo Dario. "An entropic approach to magnetized nonlocal transport and other kinetic phenomena in high-energy-density plasmas." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0336/document.

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Les simulations hydrodynamiques pour la physique de haute densité d'énergie ainsi que pour la fusion par confinement inertiel exigent une description détaillée de flux d'énergie. Le mécanisme principal est le transport électronique, qui peut être un phénoméne non local qui doit être décrit avec des modèles de Fokker-Planck, stationnaires et simplifiés dans les codes hydrodynamiques à grande échelle. Mon travail thèse est consacré au développement d'un nouveau modèle de transport non local basé sur l'utilisation d'une méthode de fermeture entropique pour la résolution des premiers moments de l'équation de Fokker-Planck agrémentée d'un opérateur de collision dédié. Une telle fermeture permet une bonne résolution des fortes anisotropies de la fonction de distribution électronique dans les régimes où le développement d'instabilités électrostatiques à petite échelle le requiert. Ce modèle aux moments (M1) est comparé avec succès au modèle de Schurtz, Nicolaï et Busquet (SNB), référent dans le domaine du transport électronique non local. Ce modèle, basé sur l'hypothèse d'une faible anisotropie de la fonction de distribution sous-jacente induisant une relation de fermeture polynomiale (P1), utilise un opérateur de collision simplifié dont nous avons proposé une amélioration. Après avoir considéré plusieurs configurations typiques de transport de chaleur, nous avons montré que le modèle M1 ultidimensionnel peut prendre naturellement en compte des effets d'un plasmas magnétisés sur le transport électronique. De plus, ce modèle permet de calculer des fonctions de distribution utiles aux études cinétiques comme la stabilité du plasma dans la zone de transport. Nous confirmons avec notre modèle que le transport d'énergie électronique peut fortement modifier l'amortissement des ondes de Langmuir et des ondes acoustiques ; contrairement aux modèles non locaux simplifiés, M1 décrit les modifications de la fonction de distribution et l'amortissement des ondes du plasma. La structure du modèle permet également de prendre en compte naturellement des champs magnétiques autogénérés, qui jouent un rôle crucial dans des simulations multidimensionnelles. Ces champs magnétiques pourraient également être étudiés pour concentrer l'énergie dans les schémas d'ignition. Enfin, nous montrons que le modèle M1 reproduit les résultats de la théorie locale élaborée par Braginskii pour tous les niveau de magnétisation et propose de nouveaux résultats pour le régime non local. Ce travail constitue une première validation de l'utilisation des fermetures entropiques, dans les régimes de faibles anisotropies, qui va s'ajouter aux tests dans les régimes fortement anisotropes Hydrodynamic simulations in high-energy-density physics and inertial con nement fusion require a detailed description of energy uxes. The leading mechanism is the electron transport, which can be a nonlocal phenomenon that needs to be described with quasistationary and simplified Fokker-Planck models in large scale hydrodynamic codes. My thesis is dedicated to the development of a new nonlocal transport model based on a fast-moving-particles collision operator and on a first moment Fokker-Planck equation, simplified with an entropic closure relation. Such a closure enables a better description of the electron distribution function in the limit of high anisotropies, where small scale electrostatic instabilities could be excited. This new model, so called M1, is successfully compared with the well known nonlocal electron transport model proposed by Schurtz, Nicolaï and Busquet, using different collision operators, and with the reduced Fokker-Planck model, based on a small-anisotropies polynomial closure relation (P1). Several typical configurations of heat transport are considered. We show that the M1 entropic model may operate in two and three dimensions and is able to account for electron transport modifications in external magnetic fields. Moreover, our model enables to compute realistic electron distribution functions, which can be used for kinetic studies, as for the plasma stability in the transport zone. It is demonstrated that the electron energy transport may strongly modify damping of Langmuir and ion acoustic waves, while the simplified nonlocal transport models are not able to describe accurately the modifications of the distribution function and plasma wave damping. The structure of the M1 model allows to naturally take into account self-generated magnetic fields, which play a crucial role in multidimensional simulations. Moreover, magnetic fields could also be used for the focusing of energetic particles in alternative ignition schemes. The M1 model reproduces the results of the local transport theory in plasma, developed by Braginskii, in a broad range of degrees of magnetization and predicts new results in the nonlocal regime. This work constitutes a first validation of the entropic closure assumption in the weakly-anisotropic regime. It can be added to the existing tests, in the strongly-anisotropic regimes

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Chrisment, Antoine. "Étude théorique du transport électronique non local dans les plasmas de fusion par confinement inertiel." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0133.

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La fusion inertielle par laser est entrée dans une nouvelle ère depuis que l'allumage a été réalisée. Le développement d'un réacteur commercial nécessite de transformer un tir réussi par an en plusieurs tirs en une seconde. Cela implique d'améliorer significativement la robustesse du contrôle de l'implosion. Pour ce faire, le dialogue entre les progrès expérimentaux et la compréhension théorique doit être renforcé par la création d'outils de simulation précis. Cette thèse aborde le problème de la modélisation du transfert électronique de chaleur dans la région de conduction de l'écoulement ablatif. Compte tenu de la variété des phénomènes à l'origine de la déformation de la fonction de distribution des électrons, il est apparu que pour fermer les équations macroscopiques, l'approche consistant à résoudre exactement des équations cinétiques réduites à l'aide d'une méthode numérique efficace est prometteuse car sa flexibilité constitue le terrain le plus fertile pour des extensions progressives. Dans ce manuscrit, nous approfondissons la compréhension, améliorons et implémentons efficacement un modèle cinétique réduit dont l'objectif est limité au traitement du problème du transport non local quasi-statique dans un plasma isolé, unidimensionnel et non magnétisé Inertial fusion by lasers has entered a new era since ignition has been achieved. The development of a commercial reactor requires to transform one successful shot per year into several ones in a second. This means significantly improving the robustness of the implosion control. To do so the dialogue between experimental progresses and theoretical understanding must be strengthened through the creation of accurate simulation tools. This thesis addresses the problem of modeling electron heat transfer within the conduction region of the ablative flow. Given the variety of phenomena causing the distortion of the electron distribution function, it appeared that to close the macroscopic equations the approach of exactly solving reduced kinetic equations with an efficient numerical method is promising since its flexibility constitutes the most fertile ground for progressive extensions. In this manuscript, we deepen the understanding, improve and efficiently implement a reduced kinetic model whose purpose is restricted to treating the problem of quasi-static nonlocal transport within an isolated, one-dimensional and unmagnetized plasma

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Silva, Suzana de Souza e. Almeida. "On the influence of nonlocal heat flux on energy transport and balance in the solar atmosphere. (Sobre a influência do fluxo de calor não local sobre o transporte e balanço de energia na atmosfera solar)." Instituto Nacional de Pesquisas Espaciais (INPE), 2017. http://urlib.net/sid.inpe.br/mtc-m21b/2016/12.24.01.22.

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In the solar corona, heat flux is one of the key processes of energy transport. Since the coronal plasma can be described as weakly collisional, classical formulation for the heat flux might no longer be the most accurate description. In a medium with fewer collisions, the heat flux will have contributions not only from neighboring particles, but also from particles coming from other regions along the magnetic field line. Hence, a better description of the heat flux in this context might be offered by a nonlocal formulation. We have implemented a non local heat flux in a 3D MHD model and we investigated its effects on the thermal evolution of the system. We simulate the evolution of plasma and magnetic field using this model and considering two different formulations for heat flux: classical (local) and nonlocal one. The initial magnetic field was obtained from a potential extrapolation of the observed line-ofsight component of photospheric magnetic field for AR11226. We evolved the system by imposing a field velocity at the bottom of the simulation box which shifted footpoints of the magnetic field lines. Then we compared the differences in the evolution of plasma obtained using the two different formulations for the heat flux. The inclusion of a nonlocal formulation for heat flux leads to considerable differences in the average temperature profile of the lower atmosphere and transition region compared to classical formulation. There are also remarkable differences concerning the contributions from energy transport and from source terms to the temperature depending on the formulation used. Our results suggest that a different heat flux formulation affects considerably the heating dynamics and temperature evolution of the plasma. Na coroa solar, o fluxo de calor é um dos principais processos de transporte de energia. Uma vez que o plasma coronal pode ser descrito como fracamente colisional, a formulação clássica para o fluxo de calor pode não ser a descrição mais precisa. Em um meio com menos colisões, o fluxo de calor terá contribuições não apenas de partículas vizinhas, mas também de partículas provenientes de outras regiões ao longo da linha de campo magnético. Assim, uma melhor descrição do fluxo de calor neste contexto pode ser oferecida por uma formulação não-local. Implementamos um fluxo de calor não-local em um modelo 3D MHD e investigamos seus efeitos na evolução térmica do sistema. Nós simulamos a evolução do plasma e campo magnético usando esse modelo considerando as seguintes formulações para o fluxo de calor: clássico (local) e não-local. O campo magnético inicial foi obtido a partir de uma extrapolação potencial da componente observada da linha de visada do campo magnético fotosférico para AR11226. Nós evoluímos o sistema impondo deslocamento dos footpoints das linhas de campo magnético. Ao final, comparamos as diferenças na evolução do plasma obtido utilizando as distintas formulações para o fluxo de calor. A inclusão de uma formulação não-local para o fluxo de calor conduz a diferenças consideráveis no perfil de temperatura média da atmosfera inferior e da região de transição em comparação com a formulação clássica. Há também diferenças notáveis quanto às contribuições do transporte de energia e dos termos de origem para a temperatura dependendo da formulação utilizada. Nossos resultados sugerem que uma formulação de fluxo de calor diferente afeta consideravelmente a dinâmica de aquecimento e a evolução da temperatura do plasma.

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Nguyen, Thi Nhu Thao. "Modélisation mathématique et simulation de la dynamique spatiale de populations de campagnols dans l’est de la France." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCD031.

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L'objectif principal de la thèse est de proposer et d'analyser des modèles mathématiques basés sur des équations aux dérivées partielles (EDP) afin de décrire la dynamique spatiale de deux espèces de campagnols (Microtus arvalis et Arvicola terrestris), qui sont particulièrement surveillés dans l'est de la France. Les modèles que nous avons proposés reposent sur des EDP qui décrivent l'évolution de la densité de la population de campagnols en fonction du temps, de l'âge et de la position dans l'espace. Nous avons suivi deux approches complémentaires pour représenter la dynamique. Dans la première approche, nous avons proposé un premier modèle qui consiste en une EDP scalaire en structurée en temps, en âge, et en espace. Elle est complétée par une condition au bord non locale. Le flux est linéaire à coefficient constant dans la direction de l'âge mais contient un terme non local dans les directions de l'espace. De plus, l'équation contient un terme de second ordre par rapport aux variables spatiales. Nous avons démontré l'existence et la stabilité de solutions faibles entropiques pour le modèle en utilisant, la compacité par compensation établie par Panov et un argument du type doublement de variables. Dans la deuxième approche, nous nous sommes inspirés du modèle Multi Agents introduit par Marilleau-Lang-Giraudoux, où la dynamique spatiale des juvéniles est découplée de l'évolution locale dans chaque parcelle. Pour mettre en place ce deuxième modèle, nous avons introduit un graphe orienté dont les nœuds sont les parcelles (ou colonies). Dans chaque nœud, l'évolution de la colonie est décrite par une équation de transport structurée en temps et en âge, et les mouvements de dispersion dans l'espace sont représentés par les passages d'un nœud à un autre. Nous avons proposé une discrétisation du modèle, par des schéma volumes finis, et, grâce à des simulations numériques, nous avons pu illustrer le fait que le modèle est capable de reproduire certaines caractéristiques qualitatives de la dynamique spatiale observée dans la nature. Nous avons ensuite proposé un troisième modèle qui est un système proie-prédateur constitué d'une équation hyperbolique pour les prédateurs et d'une équation parabolique-hyperbolique pour les proies analogue à celle proposée dans le premier modèle. Le terme de force dans l'équation des prédateurs dépend de manière non localement de la densité des proies et les deux équations sont également couplées via des termes sources classiques de type Lotka-Volterra. Nous avons établi l'existence de solutions en appliquant la méthode de la viscosité évanescente, et nous avons établi un résultat de stabilité par un argument de type doublement de variables. Enfin nous avons proposé et validé un schéma de type volumes finis pour le premier modèle.La dernière partie de mes travaux de recherche est dédiée à un projet auquel j'ai participé lors d'une école d'été CEMRACS. Il concerne un sujet de biomathématiques différent du thème principal de la thèse et porte sur un modèle épidémiologique pour la salmonellose. Nous avons proposé un nouveau cadre de modélisation générique multi-échelles de la transmission hétérogène d'agents pathogènes dans une population animale. Au niveau intra-hôte, le modèle décrit l'interaction entre le microbiote commensal, le pathogène et la réponse inflammatoire. Des fluctuations aléatoires de la dynamique écologique du microbiote individuel et de la transmission à l'échelle inter-hôte sont ajoutées pour obtenir un modèle EDP de la distribution des agents pathogènes au niveau de la population. Une extension du modèle a, par ailleurs, été développé pour représenter la transmission entre plusieurs populations. Le comportement asymptotique ainsi que l'impact des stratégies de contrôle, y compris le nettoyage et l'administration d'antimicrobiens, sont étudiés par des simulations numériques The main objective of the thesis is to propose and analyze mathematical models based on partial differential equations (PDE) to describe the spatial dynamics of two species of voles (Microtus arvalis and Arvicola terrestris), which are particularly monitored in Eastern France. The models that we have proposed are based on PDE which describe the evolution of the density of the population of voles as a function of time, age and position in space. We have two complementary approaches to represent the dynamics. In the first approach, we propose a first model that consists of a scalar PDE depending on time, age, and space supplemented with a non-local boundary condition. The flux is linear with constant coefficient in the direction of age but contains a non-local term in the directions of space. Moreover, the equation contains a second order term in the spatial variables only. We have demonstrated the existence and stability of weak entropy solutions for the model by using, respectively, the Panov's theorem of the multidimensional compensated and a doubling of the variables type argument. In the second approach we were inspired by a Multi Agent model proposed by Marilleau-Lang-Giraudoux, where the spatial dynamics of juveniles is decoupled from local evolution in each plot. To apply this model, we have introduced a directed graph whose nodes are the plots. In each node, the evolution of the colony is described by a transport equation with two variables, time and age, and the movements of dispersion, in space, are represented by the passages from one node to the other. We have proposed a discretization of the model, by finite volume methods, and noticed that this approach manages to reproduce the qualitative characteristics of the spatial dynamics observed in nature. We also proposed to consider a predator-prey system consisting of a hyperbolic equation for predators and a parabolic-hyperbolic equation for preys, where the prey's equation is analogous to the first model of the vole populations. The drift term in the predators' equation depends nonlocally on the density of prey and the two equations are also coupled via classical source terms of Lotka-Volterra type. We establish existence of solutions by applying the vanishing viscosity method, and we prove stability by a doubling of variables type argument. Moreover, concerning the numerical simulation of the first model in one-dimensional space, we obtain a finite volume discretization by using the upwind scheme and then validate the numerical scheme.The last part of my thesis work is a project in which I participated during a Summer school CEMRACS. The project was on a subject of biomathematics different from that of the thesis (an epidemiological model for salmonellosis). A new generic multi-scale modeling framework for heterogeneous transmission of pathogens in an animal population is suggested. At the intra-host level, the model describes the interaction between the commensal microbiota, the pathogen and the inflammatory response. Random fluctuations in the ecological dynamics of the individual microbiota and transmission at the inter-host scale are added to obtain a PDE model of drift-diffusion of pathogen distribution at the population level. The model is also extended to represent transmission between several populations. Asymptotic behavior as well as the impact of control strategies, including cleaning and administration of antimicrobials, are studied by numerical simulation

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Bullara, Domenico. "Nonlinear reactive processes in constrained media." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209073.

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In this thesis we show how reactive processes can be affected by the presence of different types of spatial constraints, so much so that their nonlinear dynamics can be qualitatively altered or that new and unexpected behaviors can be produced. To understand how this interplay can occur in general terms, we theoretically investigate four very different examples of this situation. The first system we study is a reversible trimolecular chemical reaction which is taking place in closed one-dimensional lattices. We show that the low dimensionality may or may not prevent the reaction from reaching its equilibrium state, depending on the microscopic properties of the molecular reactive mechanism. The second reactive process we consider is a network of biological interactions between pigment cells on the skin of zebrafish. We show that the combination of short-range and long-range contact-mediated feedbacks can promote a Turing instability which gives rise to stationary patterns in space with intrinsic wavelength, without the need of any kind of motion.Then we investigate the behavior of a typical chemical oscillator (the Brusselator) when it is constrained in a finite space. We show that molecular crowding can in such cases promote new nonlinear dynamical behaviors, affect the usual ones or even destroy them. Finally we look at the situation where the constraint is given by the presence of a solid porous matrix that can react with a perfect gas in an exothermic way. We show on one hand that the interplay between reaction, heat flux and mass transport can give rise to the propagation of adsorption waves, and on the other hand that the coupling between the chemical reaction and the changes in the structural properties of the matrix can produce sustained chemomechanical oscillations. These results show that spatial constraints can affect the kinetics of reactions, and are able to produce otherwise absent nonlinear dynamical behaviors. As a consequence of this, the usual understanding of the nonlinear dynamics of reactive systems can be put into question or even disproved. In order to have a better understanding of these systems we must acknowledge that mechanical and structural feedbacks can be important components of many reactive systems, and that they can be the very source of complex and fascinating phenomena. Doctorat en Sciences info:eu-repo/semantics/nonPublished

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Laborde, Maxime. "Systèmes de particules en interaction, approche par flot de gradient dans l'espace de Wasserstein." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLED014/document.

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Depuis l’article fondateur de Jordan, Kinderlehrer et Otto en 1998, il est bien connu qu’une large classe d’équations paraboliques peuvent être vues comme des flots de gradient dans l’espace de Wasserstein. Le but de cette thèse est d’étendre cette théorie à certaines équations et systèmes qui n’ont pas exactement une structure de flot de gradient. Les interactions étudiées sont de différentes natures. Le premier chapitre traite des systèmes avec des interactions non locales dans la dérive. Nous étudions ensuite des systèmes de diffusions croisées s’appliquant aux modèles de congestion pour plusieurs populations. Un autre modèle étudié est celui où le couplage se trouve dans le terme de réaction comme les systèmes proie-prédateur avec diffusion ou encore les modèles de croissance tumorale. Nous étudierons enfin des systèmes de type nouveau où l’interaction est donnée par un problème de transport multi-marges. Une grande partie de ces problèmes est illustrée de simulations numériques Since 1998 and the seminal work of Jordan, Kinderlehrer and Otto, it is well known that a large class of parabolic equations can be seen as gradient flows in the Wasserstein space. This thesis is devoted to extensions of this theory to equations and systems which do not have exactly a gradient flow structure. We study different kind of couplings. First, we treat the case of nonlocal interactions in the drift. Then, we study cross diffusion systems which model congestion for several species. We are also interested in reaction-diffusion systems as diffusive prey-predator systems or tumor growth models. Finally, we introduce a new class of systems where the interaction is given by a multi-marginal transport problem. In many cases, we give numerical simulations to illustrate our theorical results

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Libri sul tema "Transport nonlocal"

Morawetz, Klaus. Nonlocal Collision Integral. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198797241.003.0013.

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The kinetic equation with the nonlocal shifts is presented as the final result on the way to derive the kinetic equation with nonlocal corrections. The exclusive dependence of the nonlocal and non-instant corrections on the scattering phase shift confirms the results from the theory of gases. With the approximation on the level of the Brueckner reaction matrix, the corresponding non-instant and nonlocal scattering integral in parallel with the classical Enskog’s equation, can be treated with Monte-Carlo simulation techniques. Neglecting the shifts, the Landau theory of quasiparticle transport appears. In this sense the presented kinetic theory unifies both approaches. An intrinsic symmetry is found from the optical theorem which allows for representing the collision integral equivalently either in particle-hole symmetric or space-time symmetric form.

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Atienza, Pablo Burset. Superconductivity in Graphene and Carbon Nanotubes: Proximity Effect and Nonlocal Transport. Springer International Publishing AG, 2016.

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Atienza, Pablo Burset. Superconductivity in Graphene and Carbon Nanotubes: Proximity Effect and Nonlocal Transport. Springer London, Limited, 2013.

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Superconductivity In Graphene And Carbon Nanotubes Proximity Effect And Nonlocal Transport. Springer International Publishing AG, 2013.

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Cardaliaguet, Pierre, François Delarue, Jean-Michel Lasry, and Pierre-Louis Lions. The Master Equation and the Convergence Problem in Mean Field Games. Princeton University Press, 2019. http://dx.doi.org/10.23943/princeton/9780691190716.001.0001.

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This book describes the latest advances in the theory of mean field games, which are optimal control problems with a continuum of players, each of them interacting with the whole statistical distribution of a population. While it originated in economics, this theory now has applications in areas as diverse as mathematical finance, crowd phenomena, epidemiology, and cybersecurity. Because mean field games concern the interactions of infinitely many players in an optimal control framework, one expects them to appear as the limit for Nash equilibria of differential games with finitely many players as the number of players tends to infinity. The book rigorously establishes this convergence, which has been an open problem until now. The limit of the system associated with differential games with finitely many players is described by the so-called master equation, a nonlocal transport equation in the space of measures. After defining a suitable notion of differentiability in the space of measures, the authors provide a complete self-contained analysis of the master equation. Their analysis includes the case of common noise problems in which all the players are affected by a common Brownian motion. They then go on to explain how to use the master equation to prove the mean field limit. The book presents two important new results in mean field games that contribute to a unified theoretical framework for this exciting and fast-developing area of mathematics.

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Capitoli di libri sul tema "Transport nonlocal"

Burset Atienza, Pablo. "Nonlocal Transport in Graphene." In Superconductivity in Graphene and Carbon Nanotubes. Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-01110-3_5.

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Sellitto, Antonio, Vito Antonio Cimmelli, and David Jou. "Weakly Nonlocal and Nonlinear Heat Transport." In Mesoscopic Theories of Heat Transport in Nanosystems. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-27206-1_5.

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O’Malley, Daniel, and John H. Cushman. "Nonlocal Models for Transport in Fractal Media." In Fractals. CRC Press, 2017. http://dx.doi.org/10.1201/9781315152264-6.

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Otani, Yoshichika, Takashi Kimura, Yasuhiro Niimi, and Hiroshi Idzuchi. "Nonlocal Spin Valves in Metallic Nanostructures." In Spintronics Handbook: Spin Transport and Magnetism, Second Edition. CRC Press, 2019. http://dx.doi.org/10.1201/9780429441189-9.

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Lagoutière, Frédéric, and Nicolas Vauchelet. "Analysis and Simulation of Nonlinear and Nonlocal Transport Equations." In Innovative Algorithms and Analysis. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-49262-9_10.

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Alvarez, F. X., D. Jou, and A. Sellitto. "Nonlocal Transport Equations for Small Systems and Fast Processes." In Encyclopedia of Continuum Mechanics. Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53605-6_64-1.

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Alvarez, F. X., D. Jou, and A. Sellitto. "Nonlocal Transport Equations for Small Systems and Fast Processes." In Encyclopedia of Continuum Mechanics. Springer Berlin Heidelberg, 2019. http://dx.doi.org/10.1007/978-3-662-53605-6_64-2.

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Alvarez, Francesc Xavier, David Jou, and Antonio Sellitto. "Nonlocal Transport Equations for Small Systems and Fast Processes." In Encyclopedia of Continuum Mechanics. Springer Berlin Heidelberg, 2020. http://dx.doi.org/10.1007/978-3-662-55771-6_64.

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Hoang, Vu, and Maria Radosz. "A Note on Singularity Formation for a Nonlocal Transport Equation (Research)." In Advances in Mathematical Sciences. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-42687-3_15.

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Tsukagoshi, Kazuhito, Kenichi Oto, Sadao Takaoka, et al. "Spin-Dependent Nonlocal Quantum Transport Influenced by Gate Voltage in GaAs/AlGaAs Wires." In Science and Technology of Mesoscopic Structures. Springer Japan, 1992. http://dx.doi.org/10.1007/978-4-431-66922-7_20.

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Atti di convegni sul tema "Transport nonlocal"

Yu, Xin, Deyin Zheng, Jianyu Du, Chi Zhang, and Wei Wang. "Integrating Nanoscale Dynamics for Enhanced Evaporation: A Theoretical Framework Addressing Nonlocal Transport in Nanopores." In 2024 25th International Conference on Electronic Packaging Technology (ICEPT). IEEE, 2024. http://dx.doi.org/10.1109/icept63120.2024.10668497.

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Mima, K., M. Honda, S. Miyamoto, and S. Kato. "Effects of nonlocal heat transport on laser implosion." In Laser interaction and related plasma phenomena: 12th international conference. AIP, 1996. http://dx.doi.org/10.1063/1.50373.

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Jin, Seonghoon, Sung-min Hong, Jongchol Kim, Young J. Park, and Hong S. Min. "Nonlocal transport and thermal noise of the nanoscale MOSFET." In Second International Symposium on Fluctuations and Noise, edited by Francois Danneville, Fabrizio Bonani, M. Jamal Deen, and Michael E. Levinshtein. SPIE, 2004. http://dx.doi.org/10.1117/12.546941.

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Hamba, Fujihiro. "NONLOCAL TRANSPORT OF PASSIVE SCALAR IN TURBULENT CHANNEL FLOW." In Third Symposium on Turbulence and Shear Flow Phenomena. Begellhouse, 2003. http://dx.doi.org/10.1615/tsfp3.540.

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Hamba, Fujihiro. "NONLOCAL ANALYSIS OF MOMENTUM TRANSPORT IN TURBULENT CHANNEL FLOW." In Fourth International Symposium on Turbulence and Shear Flow Phenomena. Begellhouse, 2005. http://dx.doi.org/10.1615/tsfp4.250.

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Kaganovich, I. D., Y. Raitses, A. V. Khrabrov, V. I. Demidov, and D. Sydorenko. "Nonlocal collisionless and collisional electron transport in low temperature plasmas." In 2010 IEEE 37th International Conference on Plasma Sciences (ICOPS). IEEE, 2010. http://dx.doi.org/10.1109/plasma.2010.5534359.

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Bychenkov, V. Y., S. G. Bochkarev, Wojciech Rozmus, O. V. Batishchev, J. J. Martinell, and T. K. Soboleva. "Nonthermal tails of the electron distribution functions with nonlocal transport." In ECLIM 2002: 27th European conference on Laser Interaction with Matter, edited by Oleg N. Krokhin, Sergey Y. Gus'kov, and Yury A. Merkul'ev. SPIE, 2003. http://dx.doi.org/10.1117/12.536948.

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Klimova, A. V. "The nonlocal electron transport in transistor structures with submicron surface relief." In 2005 15th International Crimean Conference Microwave and Telecommunication Technology. IEEE, 2005. http://dx.doi.org/10.1109/crmico.2005.1565000.

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Lesev, Vadim N., Anna O. Zheldasheva, Oksana I. Bzheumikhova, and Cantemir M. Gukezhev. "On a Nonlocal Model with Operators of Fractional Integro-Differentiation." In 2018 IEEE International Conference "Quality Management, Transport and Information Security, Information Technologies" (IT&QM&IS). IEEE, 2018. http://dx.doi.org/10.1109/itmqis.2018.8525069.

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Sibatov, Renat, Anatoly Erlykin, Vladimir Uchaikin, and Arnold Wolfendale. "A Look at the Cosmic Ray Anisotropy with the Nonlocal Relativistic Transport Approach." In The 34th International Cosmic Ray Conference. Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.236.0463.

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Rapporti di organizzazioni sul tema "Transport nonlocal"

Linn, R. R., T. T. Clark, F. H. Harlow, and L. Turner. Turbulence transport with nonlocal interactions. Office of Scientific and Technical Information (OSTI), 1998. http://dx.doi.org/10.2172/645494.

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Spizzo, G., R. B. White, S. Cappello, and L. Marrelli. Nonlocal Transport in the Reversed Field Pinch. Office of Scientific and Technical Information (OSTI), 2009. http://dx.doi.org/10.2172/965276.

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Rax, J. M., and R. B. White. Nonlocal heat transport in a stochastic magnetic field. Office of Scientific and Technical Information (OSTI), 1991. http://dx.doi.org/10.2172/6255493.

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Brunner, S., E. Valeo, and J. A. Krommes. Linear delta-f simulations of nonlocal electron heat transport. Office of Scientific and Technical Information (OSTI), 2000. http://dx.doi.org/10.2172/750428.

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D'Elia, Marta, Christian Glusa, Xiao Xu, and John Foster. Machine-learning of nonlocal kernels for anomalous subsurface transport from breakthrough curves. Office of Scientific and Technical Information (OSTI), 2022. http://dx.doi.org/10.2172/1842267.

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Cushman, J. H. Nonlocal transport of chemically reactive, degradable species in heterogeneous porous media. Final report. Office of Scientific and Technical Information (OSTI), 1998. http://dx.doi.org/10.2172/303999.

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D'Elia, Marta, and Mamikon Gulian. Analysis of Anisotropic Nonlocal Diffusion Models: Well-posedness of Fractional Problems for Anomalous Transport. Office of Scientific and Technical Information (OSTI), 2021. http://dx.doi.org/10.2172/1763574.

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D'Elia, Marta, Mamikon Gulian, Jorge Suzuki, and Mohsen Zayernouri. Fractional Modeling in Action: A Survey of Nonlocal Models for Subsurface Transport, Turbulent Flows, and Anomalous Materials. Office of Scientific and Technical Information (OSTI), 2021. http://dx.doi.org/10.2172/1820001.

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Kissick, M. W., J. D. Callen, and E. D. Fredrickson. Required conditions for and coincident 1/1-mode activity associated with the nonlocal electron heat transport effect on TFTR. Office of Scientific and Technical Information (OSTI), 1997. http://dx.doi.org/10.2172/532611.

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