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Propagating Terraces And The Dynamics Of Front Like Solutions Of Reaction Diffusion Equations On Mathbbr
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Book Synopsis Propagating Terraces and the Dynamics of Front-Like Solutions of Reaction-Diffusion Equations on Mathbb{R} by : Peter Poláčik
Download or read book Propagating Terraces and the Dynamics of Front-Like Solutions of Reaction-Diffusion Equations on Mathbb{R} written by Peter Poláčik and published by . This book was released on 2020 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: The author considers semilinear parabolic equations of the form u_t=u_xx+f(u),\quad x\in \mathbb R,t>0, where f a C^1 function. Assuming that 0 and \gamma >0 are constant steady states, the author investigates the large-time behavior of the front-like solutions, that is, solutions u whose initial values u(x,0) are near \gamma for x\approx -\infty and near 0 for x\approx \infty . If the steady states 0 and \gamma are both stable, the main theorem shows that at large times, the graph of u(\cdot ,t) is arbitrarily close to a propagating terrace (a system of stacked traveling fonts). The author.
Book Synopsis Traveling Front Solutions in Reaction-Diffusion Equations by : Masaharu Taniguchi
Download or read book Traveling Front Solutions in Reaction-Diffusion Equations written by Masaharu Taniguchi and published by . This book was released on 2021-05-28 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study on traveling fronts in reaction-diffusion equations is the first step to understand various kinds of propagation phenomena in reaction-diffusion models in natural science. One dimensional traveling fronts have been studied from the 1970s, and multidimensional ones have been studied from around 2005. This volume is a text book for graduate students to start their studies on traveling fronts. Using the phase plane analysis, we study the existence of traveling fronts in several kinds of reaction-diffusion equations. For a nonlinear reaction term, a bistable one is a typical one. For a bistable reaction-diffusion equation, we study the existence and stability of two-dimensional V-form fronts, and we also study pyramidal traveling fronts in three or higher space dimensions. The cross section of a pyramidal traveling front forms a convex polygon. It is known that the limit of a pyramidal traveling front gives a new multidimensional traveling front. For the study the multidimensional traveling front, studying properties of pyramidal traveling fronts plays an important role. In this volume, we study the existence, uniqueness and stability of a pyramidal traveling front as clearly as possible for further studies by graduate students. For a help of their studies, we briefly explain and prove the well-posedness of reaction-diffusion equations and the Schauder estimates and the maximum principles of solutions.Published by Mathematical Society of Japan and distributed by World Scientific Publishing Co. for all markets
Book Synopsis Front Propagation for Reaction-diffusion Equations of Bistable Type by : G. Barles
Download or read book Front Propagation for Reaction-diffusion Equations of Bistable Type written by G. Barles and published by . This book was released on 1990 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Propagation in Reaction-diffusion Equations with Fractional Diffusion by : Anne-Charline Coulon
Download or read book Propagation in Reaction-diffusion Equations with Fractional Diffusion written by Anne-Charline Coulon and published by . This book was released on 2014 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the long time behaviour of solutions to Fisher-KPP reaction-diffusion equations involving fractional diffusion. This type of equation arises, for example, in spatial propagation or spreading of biological species (rats, insects,...). In population dynamics, the quantity under study stands for the density of the population. It is well-known that, under some specific assumptions, the solution tends to a stable state of the evolution problem, as time goes to infinity. In other words, the population invades the medium, which corresponds to the survival of the species, and we want to understand at which speed this invasion takes place. To answer this question, we set up a new method to study the speed of propagation when fractional diffusion is at stake and apply it on three different problems. Part I of the thesis is devoted to an analysis of the asymptotic location of the level sets of the solution to two different problems : Fisher-KPP models in periodic media and cooperative systems, both including fractional diffusion. On the first model, we prove that, under some assumptions on the periodic medium, the solution spreads exponentially fast in time and we find the precise exponent that appears in this exponential speed of propagation. We also carry out numerical simulations to investigate the dependence of the speed of propagation on the initial condition. On the second model, we prove that the speed of propagation is once again exponential in time, with an exponent depending on the smallest index of the fractional Laplacians at stake and on the reaction term. Part II of the thesis deals with a two dimensional environment, where reproduction of Fisher-KPP type and usual diffusion occur, except on a line of the plane, on which fractional diffusion takes place. The plane is referred to as 'the field' and the line to 'the road', as a reference to the biological situations we have in mind. Indeed, it has long been known that fast diffusion on roads can have a driving effect on the spread of epidemics. We prove that the speed of propagation is exponential in time on the road, whereas it depends linearly on time in the field. Contrary to the precise asymptotics obtained in Part I, for this model, we are not able to give a sharp location of the level sets on the road and in the field. The expansion shape of the level sets in the field is investigated through numerical simulations.
Book Synopsis Propagation Phenomena in Reaction-advection-diffusion Equations by : Christopher Henderson
Download or read book Propagation Phenomena in Reaction-advection-diffusion Equations written by Christopher Henderson and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Reaction-advection-diffusion (RAD) equations are a class of non-linear parabolic equations which are used to model a diverse range of biological, physical, and chemical phenomena. Originally introduced in the early twentieth century as a model for population dynamics, they have been used in recent years in diverse contexts including climate change, criminal behavior, and combustion. These equations are characterized by the combination of three behaviors: spreading, stirring, and growth/decay. The main focus of mathematical research into RAD equations over the past century has been in characterizing the propagation of solutions. Indeed, these equations are characterized by the invasion of an unstable state by a stable state at a constant rate (for instance, the invasion of empty space by a population until the environmental carrying capacity is reached). In general, this can be characterized by the existence, uniqueness, and stability of traveling wave solutions, or solutions with a fixed profile which move at a constant speed in time. In general, the speed and shape of these traveling waves gives us the speed with which the stable state invades the unstable state. This thesis assumes the following trajectory, investigating two specific RAD equations: the Fisher-KPP equation, used in population dynamics, and a coupled reactive-Boussinesq system, used to model combustion in a fluid. For the former equation, we prove results regarding the precise spreading rate, and for the latter equation, we prove an existence result for a special solution that generalizes the traveling wave. In the first part of this thesis, we prove two results quantifying the precise speed of spreading for solutions to the Cauchy problem of the Fisher-KPP equation. The first of these results, concerning localized initial data, provides intuition for a lower order term obtained non-rigorously in. Specifically, we prove a quantitative convergence-to-equilibrium result in a related model, which has been used as a close approximation of the Fisher-KPP equation. The second of these results, concerning non-localized initial data and building on the work of Hamel and Roques, quantifies the super-linear in time spreading of the population. Here we compute the highest order term in the spreading for a broad class of initial data. In the second part of this thesis, we look at a coupled system that models combustion in a fluid, and we prove a qualitative propagation result. Unlike classical models, this relatively new system accounts for the effect of advection induced by the buoyancy force that results from the evolution of the temperature. Essentially, this means that we take into account the phenomenon that ``hot air rises.'' We exhibit a generalized traveling wave solution of this system, called a pulsating front, in two-dimensional periodic domains. To our knowledge, this is the first result regarding the existence of ``pulsating fronts'' in a coupled system.
Book Synopsis Two Examples of Reaction-diffusion Front Propagation in Heterogeneous Media by : Antoine Pauthier
Download or read book Two Examples of Reaction-diffusion Front Propagation in Heterogeneous Media written by Antoine Pauthier and published by . This book was released on 2016 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this thesis is to study two examples of propagation phenomena in heterogeneous reaction-diffusion equations.The purpose of the first part is to understand the effect of nonlocal exchanges between a line of fast diffusion and a two dimensional environment in which reaction-diffusion of KPP type occurs. The initial model was introduced in 2013 by Berestycki, Roquejoffre, and Rossi. In the first chapter we investigate how the nonlocal coupling between the line and the plane enhances the spreading in the direction of the line; we also investigate how different exchange functions may maximize or not the spreading speed.The second chapter is concerned with the singular limit of nonlocal exchanges that tend to Dirac masses. We show the convergence of the dynamics in a rather strong sense. In the third chapter we study the limit of long range exchanges with constant mass. It gives an infimum for the asymptotic speed of spreading for these models that still could be bigger than the usual KPP spreading speed.The second part of this thesis is concerned with entire solutions for heterogeneous bistable equations.We consider a two dimensional domain infinite in one direction, bounded in the other, that converges to a cylinder as x goes to minus infinity. We prove the existence of an entire solution in such a domain which is the bistable wave for t tends to minus infinity. It also lead us to investigate a one dimensional model with a non-homogeneous reaction term,for which we prove the same property.
Book Synopsis Traveling Wave Solutions of Parabolic Systems by : A. I. Volpert
Download or read book Traveling Wave Solutions of Parabolic Systems written by A. I. Volpert and published by American Mathematical Soc.. This book was released on with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: The theory of travelling waves described by parabolic equations and systems is a rapidly developing branch of modern mathematics. This book presents a general picture of current results about wave solutions of parabolic systems, their existence, stability, and bifurcations. With introductory material accessible to non-mathematicians and a nearly complete bibliography of about 500 references, this book is an excellent resource on the subject.
Book Synopsis Biological Invasions: Theory and Practice by : Nanako Shigesada
Download or read book Biological Invasions: Theory and Practice written by Nanako Shigesada and published by Oxford University Press, UK. This book was released on 1997-02-06 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the ecological effect a species can have when it moves into an environment that it has not previously occupied (commonly referred to as an 'Invasion'). It is unique in presenting a clear and accessible introduction to a highly complex area - the modelling of biological invasions. The book presents the latest theories and models developed from studies into this crucial area. It includes data and examples from biological case studies showing how the models can be applied to the study of invasions, whether dealing with AIDS, the European rabbit, or prickly pear cactuses. - ;In nature, all organisms migrate or disperse to some extent, either by walking, swimming, flying, or being transported by wind or water. When a species succeeds in colonising an area that it has not previously inhabited, this is referred to as an `invasion'. Humans can precipitate biological invasions often spreading disease or pests by their travels around the world. Using the large amount of data that has been collected from studies worldwide, ranging from pest control to epidemiology, it has been possible to construct mathematical models that can predict which species will become an invader, what kind of habitat is susceptible to invasion by a particular species, and how fast an invasion will spread if it occurs. This book presents a clear and accessible introduction to this highly complex area. Included are data and examples from biological case studies showing how these models can be applied to the study of invasions, whether dealing with AIDS, the European rabbit, or prickly pear cactuses. -
Book Synopsis Dynamical Systems in Population Biology by : Xiao-Qiang Zhao
Download or read book Dynamical Systems in Population Biology written by Xiao-Qiang Zhao and published by Springer Science & Business Media. This book was released on 2013-06-05 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: Population dynamics is an important subject in mathematical biology. A cen tral problem is to study the long-term behavior of modeling systems. Most of these systems are governed by various evolutionary equations such as difference, ordinary, functional, and partial differential equations (see, e. g. , [165, 142, 218, 119, 55]). As we know, interactive populations often live in a fluctuating environment. For example, physical environmental conditions such as temperature and humidity and the availability of food, water, and other resources usually vary in time with seasonal or daily variations. Therefore, more realistic models should be nonautonomous systems. In particular, if the data in a model are periodic functions of time with commensurate period, a periodic system arises; if these periodic functions have different (minimal) periods, we get an almost periodic system. The existing reference books, from the dynamical systems point of view, mainly focus on autonomous biological systems. The book of Hess [106J is an excellent reference for periodic parabolic boundary value problems with applications to population dynamics. Since the publication of this book there have been extensive investigations on periodic, asymptotically periodic, almost periodic, and even general nonautonomous biological systems, which in turn have motivated further development of the theory of dynamical systems. In order to explain the dynamical systems approach to periodic population problems, let us consider, as an illustration, two species periodic competitive systems dUI dt = !I(t,Ul,U2), (0.
Book Synopsis Patterns of Dynamics by : Pavel Gurevich
Download or read book Patterns of Dynamics written by Pavel Gurevich and published by Springer. This book was released on 2018-02-07 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical advances in dynamical-systems theory and their applications to pattern-forming processes in the sciences and engineering are discussed in this volume that resulted from the conference Patterns in Dynamics held in honor of Bernold Fiedler, in Berlin, July 25-29, 2016.The contributions build and develop mathematical techniques, and use mathematical approaches for prediction and control of complex systems. The underlying mathematical theories help extract structures from experimental observations and, conversely, shed light on the formation, dynamics, and control of spatio-temporal patterns in applications. Theoretical areas covered include geometric analysis, spatial dynamics, spectral theory, traveling-wave theory, and topological data analysis; also discussed are their applications to chemotaxis, self-organization at interfaces, neuroscience, and transport processes.
Book Synopsis Periodic-parabolic Boundary Value Problems and Positivity by : Peter Hess
Download or read book Periodic-parabolic Boundary Value Problems and Positivity written by Peter Hess and published by Longman. This book was released on 1991 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: In these notes we give a unified treatment of semilinear nonautonomous diffusion equations and systems thereof, which satisfy a comparison principle, and whose coefficient functions depend periodically on time. Such equations arise naturally, e. g. in biomathematics if one admits dependence of the data on daily, monthly, or seasonal variations. Typical examples considered are the logistic equation with diffusion, Fisher's equation of population genetics, and Volterra-Lotka systems (with diffusion) of competition and of the predator-prey type. The existence and qualitative properties of periodic solutions, and the asymptotic behaviour of solutions of the initial-value problem are studied. Basic underlying concepts are strongly order-preserving discrete semigroups and the principal eigenvalue of a periodic-parabolic operator.
Book Synopsis Nonlinear Diffusion Problems by : Odo Diekmann
Download or read book Nonlinear Diffusion Problems written by Odo Diekmann and published by . This book was released on 1976 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Reaction-Diffusion Equations and Propagation Phenomena by : Henri Berestycki
Download or read book Reaction-Diffusion Equations and Propagation Phenomena written by Henri Berestycki and published by Springer Verlag. This book was released on 2007-01-01 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is about reaction-diffusion equations in unbounded domains with a special emphasis on traveling waves and their generalizations as well as on different notions of propagation. It includes a general presentation of all the classical results in this area. Even for some well known results, in some cases, original proofs are included which are simpler and more elegant than the known ones. The book gives a fairly comprehensive and coherent account of the recent developments and current research in this active area. It also contains some of the basic results about elliptic and parabolic partial differential equations and a chapter on the different versions of the maximum principles. Thus, it also serves as an introduction to these topics. Each chapter is made as much autonomous as possible. Each one has a specific introduction as well as brief mentions of extensions or of related subjects. Some outstanding open problems are mentioned along the way. Each introduction states the goals of the chapter, some of its main results, the framework and indicates how the chapter is organized. The book is addressed to researchers and graduate students in mathematics, in particular in analysis, partial differential equations and applied mathematics. It will be of interest as well to researchers and graduate students concerned by mathematical modeling in physics and in biology. It is planed to be a reference book of lasting value with all the important results on a topic which is commonly used in these fields.
Book Synopsis Monotone Dynamical Systems: An Introduction to the Theory of Competitive and Cooperative Systems by : Hal L. Smith
Download or read book Monotone Dynamical Systems: An Introduction to the Theory of Competitive and Cooperative Systems written by Hal L. Smith and published by American Mathematical Soc.. This book was released on 1995 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents comprehensive treatment of a rapidly developing area with many potential applications: the theory of monotone dynamical systems and the theory of competitive and cooperative differential equations. The primary aim is to provide potential users of the theory with techniques, results, and ideas useful in applications, while at the same time providing rigorous proofs. Among the topics discussed in the book are continuous-time monotone dynamical systems, and quasimonotone and nonquasimonotone delay differential equations. The book closes with a discussion of applications to quasimonotone systems of reaction-diffusion type. Throughout the book, applications of the theory to many mathematical models arising in biology are discussed. Requiring a background in dynamical systems at the level of a first graduate course, this book is useful to graduate students and researchers working in the theory of dynamical systems and its applications.
