Ces travaux concernent deux équations paraboliques, dégénérées et non-locales. La première équation est une équation de films minces fractionnaire et la deuxième est une équation des milieux poreux fractionnaire. La présentation des problèmes, les résultats existants dans la littérature, ainsi que le résumé de nos résultats font l'objet de l'introduction. Le deuxième chapitre est consacré à la présentation de la méthode de De Giorgi utilisée pour montrer la régularité Hölder des solutions des équations elliptiques. On présente de plus les résultats utilisant cette approche dans les cas paraboliques local et non-local. Dans le troisième chapitre, on montre l'existence de solutions faibles d'une équation des films minces fractionnaire. C'est une équation parabolique, dégénérée, non-locale d'ordre $alpha+2$ où $0 < alpha < 2$. C'est une généralisation d'une équation étudiée par Imbert et Mellet en 2011 pour $alpha = 1$. Pour construire les solutions, on passe par un problème régularisé. En utilisant les injections de Sobolev, on passe à la limite pour trouver des solutions faibles. Vu la différence des injections de Sobolev, on distingue deux cas $0 <alpha < 1$ et $1 leq alpha < 2$. Dans les deux cas on démontre que la solution est positive si la condition initiale l'est. Le quatrième chapitre concerne une équation des milieux poreux fractionnaire. On montre la régularité Hölder de solutions faibles positives satisfaisant des estimées d'énergie. D'abord, on montre l'existence de solutions faibles qui satisfont des estimées d'énergie. On distingue deux cas $0 <alpha < 1$ et $1 leq alpha < 2$ à cause de problème de divergence. Puis on démontre les lemmes de De Giorgi qui sont des lemmes de réduction de l'oscillation d'en dessus et d'au-dessous. Ces deux lemmes ne suffisent pas pour montrer la régularité Hölder. On a besoin d'améliorer le résultat du lemme de réduction de l'oscillation d'en dessus. Donc, on passe par un lemme des valeurs intermédiaires et on montrer un lemme de réduction de l'oscillation d'en dessus amélioré. Enfin, on montre la régularité Hölder des solutions en utilisant la propriété scaling de ces solutions / In this thesis, we study two degenerate, non-local parabolic equations, a fractional thin film equation and a fractional porous medium equation. The introduction contains a presentation of problems, the previous results in the literature and a brief presentation of our results. In the second chapter, we present a short overview of the De Giorgi method used to prove Hölder regularity of solutions of elliptic equations. Moreover, we present the results using this approach in the local and non-local parabolic cases. In the third chapter we prove existence of weak solutions of a fractional thin film equation. It is a non-local degenerate parabolic equation of order $alpha + 2$ where $0 < alpha < 2$. It is a generalization of an equation studied by Imbert and Mellet in 2011 for $alpha = 1$. To construct these solutions, we consider a regularized problem then we pass to the limit using Sobolev embedding theorem, that's why we distinguish two cases $0 < alpha < 1$ and $1 leq alpha < 2$. We also prove that the solution is positive if the initial condition is so. The fourth chapter is dedicated for a fractional porous medium equation. We prove Hölder regularity of positive weak solutions satisfying energy estimates. First, we prove the existence of weak solutions that satisfy energy estimates. We distiguish two cases $0 < alpha < 1$ and $1 leq alpha < 2$ because of divergence problems. The we prove De Giorgi Lemmas about oscillation reduction from above and from below. This is not suffisant. We need to improve the lemma about oscillation reduction from above. So we pass by an intermediate values lemma and we prove an improved oscillation reduction lemma from above. Finally, we prove Hölder regularity of solutions using the scaling property

This thesis uses a method called "parabolic equation approach." This method can treat both the variations of the terrain and the refractive index simultaneously. This method makes it possible to predict the radio propagation more precisely. We can discuss the effects of the variations of the refractive index to radio signal and demo effects by using parabolic equation method. The Effective Earth Radius Factor is 4/3 suggested by CCIR so-called "Standard Atmosphere Model". But we try to find more suitable K in the Southern Taiwan area. We adopt Parabolic Equation Propagation Model to simulate real situation of radio propagation in the Southern Taiwan area and the prediction is compared with the measurement obtained previously. We can get the best K in the Southern Taiwan area is 1.8 and 1.9. The best K is greater than the value of 4/3 suggested by CCIR. Recently the government on Taiwan release more radio broadcasting licenses to the general public. As the number of radio stations increases, the interference between stations becomes more likely. There have been reports about the poor quality of broadcasting from stations. In this paper, we will study the interference using FM radio stations as an example. Given the characteristics of the transmitting antenna including location, frequency, pattern, height and power, the field strength can be computed with the equivalent earth radius factor K as a parameter. The difference in interference level is obtained under the standard atmosphere (K=4/3) and a case of K=1.55 which has been reported to be more suitable in Taiwan. Finally an extreme case that a ducting exists will be studied. Our results can be used to find more suitable separation distances free from interferences between co-channel and adjacent channel stations. By including a realistic tropospheric term, the more accurate field strength predictions can give the Spectrum Authority a better spectrum assignment tool. This has the potential to increase the number of available stations that can be made available or to reduce the interference stations may experience.

An optimal control problem governed by the heat equation with nonlinear boundary conditions is considered. The objective functional consists of a quadratic terminal part and a quadratic regularization term. It is known, that an SQP method converges quadratically to the optimal solution of the problem. To handle the quadratic optimal control subproblems with high precision, very large scale mathematical programming problems have to be treated. The constrained problem is reduced to an unconstrained one by a method due to Bertsekas. A multigrid approach developed by Hackbusch is applied to solve the unconstrained problems. Some numerical examples illustrate the behaviour of the method.

This thesis provides an analytical and two numerical methods for solving a parabolic equation of two-dimensional mean curvature flow with some applications. In analytical method, this equation is solved by Lie group analysis method, and in numerical method, two algorithms are implemented in MATLAB for solving this equation. A geometric algorithm and a step-wise algorithm; both are based on a deterministic game theoretic representation for parabolic partial differential equations, originally proposed in the genial work of Kohn-Serfaty [1]. / +46-767165881

Magistriniame darbe tiriama trisluoksnė skirtuminė schema parabolinei lygčiai su integraline sąlyga. Aprašomi metodai skaitiniai diferencialinių kraštinių uţdavinių su nelokaliosiomis sąlygomis. Atlikto magistrinio darbo rezultatas papildo iki šiol kitų mokslininkų gautus rezultatus tiriant trisluoksnę skirtuminę schemą. Magistro darbą sudaro: įvadas, uţdavinio formulavimas, 4 pagrindinės dalys, uždavinio sprendimas bei išvados. Įvadiniame skyriuje aptariamas temos aktualumas ir darbo tikslas, nurodomi naudojamo tyrimo metodai. Antrajame skyriuje suformuluojamas diferencialinis ir skirtuminis uždavinys su nelokaliąja integraline sąlyga. Trečiajame skyriuje užrašoma trisluoksnė schema kanoniniu pavidalu. Ketvirtajame skyriuje suvedame trisluoksnę schemą į dvisluoksnę. Penktajame skyriuje pateikiamas neišreikštinių skirtuminių lygčių algoritmas. Šeštajame nagrinėjama išreikštinė trisluoksnė schema bei jos algoritmas. Septintajame skyriuje tiriame matricos spektro struktūrą. Aštuntajame sprendžiamas konkretus uždavinys. Pateikiamos viso darbo bendrosios išvados. / In this master thesis there was investigated difference scheme for parabolic equation with integral condition. Numerical methods for solution differential boundary value problem nonlocal conditions methods investigated. Results of this completed work supplements by other scientists until now received results of investigation of three- layer difference scheme. Master thesis consists of introduction, problem formulation, four main chapter, numerical experiment and conclusions. Introductory chapter discusses relevance of the topic and the goal of this work, specifies methods that were used for this investigation. The second chapter formulates the differential task with nonlocal integral condition. In the third chapter is written a three- layer scheme in canonical form. In the fourth chapter the three-layer scheme reduce to the two-layers scheme. The fifth chapter presens the algorithm of realization of impicit scheme. The sixth chapter presents explicit three-layer scheme. The seventh chapter studies the structure of the matrix spectrum. There are presented all the general conclusions of the work.

Ocean environments with sloped seafloors can give rise to sound paths that do not remain in a constant plane of propagation. Numerical modelling of sound fields in such environments requires the use of computer models that fully account for out-of-plane sound propagation effects. The inclusion of these three-dimensional effects can be computationally intensive and the effects are often neglected in computer sound propagation codes. The current state-of-the art in sound propagation modelling has seen the development of models that can fully account for out-of-plane sound propagation. Such a model has been implemented in this research to provide acoustic consultants JASCO Applied Sciences with an important tool for environmental noise impact assessment in complicated marine environments. The model is described and validation results are shown for benchmark test cases. The model is also applied to study three-dimensional propagation effects in measured data from a realistic ocean environment. Particular analysis techniques assist in the interpretation of the modelled sound field for this physical test environment providing new insight into the characteristics of the test environment. / Graduate

We consider a class of control problems governed by a linear parabolic initial-boundary value problem with linear-quadratic objective and pointwise constraints on the control. The control system contains different types of perturbations. They appear in the linear part of the objective functional, in the right hand side of the equation, in its boundary condition, and in the initial value. Making use of parabolic regularity in the whole scale of $L^p$ the known Lipschitz stability in the $L^2$-norm is improved to the supremum-norm.

Darbo tikslas - išnagrinėti dvimatės parabolinio tipo lygties su nelokaliąja integraline sąlyga sprendimą baigtinių skirtumų metodu. Išnagrinėtas kintamųjų krypčių metodo algoritmas tokiam uždaviniui spręsti. Išnagrinėtas dvimatės parabolinės lygties su keliomis nelokaliosiomis integralinėmis kraštinėmis sąlygomis sprendimas kintamųjų krypčių metodu. Uždavinio sprendinys randamas papildomai išsprendžiant neaukštos eilės algebrinę tiesinių lygčių sistemą, kuri sudaroma panaudojant nelokaliąsias integralines sąlygas. Išanalizuota skirtuminio operatoriaus su nelokaliosiomis sąlygomis spektro struktūra. Spektro struktūra išanalizuota tuo tikslu, kad galima būtų išnagrinėti dvimačio parabolinio uždavinio su viena nelokaliąja integraline sąlyga sprendžiamo kintamųjų krypčių ar lokaliai vienmačiu metodu, stabilumą. Nustatyta nelokaliosios sąlygos įtaka spektro struktūrai. Sudarytas elipsinio uždavinio su papildoma nelokaliąja sąlyga sprendimo algoritmas. / The aim of the work is to analyze the finite difference method for solving two-dimensional parabolic equation with an integral boundary condition. The alternating direction method for solving the problem of this kind is analyzed. This method is applied the alternating direction method for solving two-dimensional parabolic equation with two nonlocal integral condition is analyzed. Solution of the problem is found by resolving an additional linear system of equations of lower order . Structure of the spectrum for difference operator with nonlocal condition is analyzed. In order to analyze stability of two-dimensional parabolic equation with one integral condition the structure of spectrum is analyzed. Influence of nonlocal condition for structure of the spectrum is determined. The finite difference method for elliptic problem is constructed.

The aim of the work is to analyze the finite difference method for solving two-dimensional parabolic equation with an integral boundary condition. The alternating direction method for solving the problem of this kind is analyzed. This method is applied the alternating direction method for solving two-dimensional parabolic equation with two nonlocal integral condition is analyzed. Solution of the problem is found by resolving an additional linear system of equations of lower order . Structure of the spectrum for difference operator with nonlocal condition is analyzed. In order to analyze stability of two-dimensional parabolic equation with one integral condition the structure of spectrum is analyzed. Influence of nonlocal condition for structure of the spectrum is determined. The finite difference method for elliptic problem is constructed. / Darbo tikslas - išnagrinėti dvimatės parabolinio tipo lygties su nelokaliąja integraline sąlyga sprendimą baigtinių skirtumų metodu. Išnagrinėtas kintamųjų krypčių metodo algoritmas tokiam uždaviniui spręsti. Išnagrinėtas dvimatės parabolinės lygties su keliomis nelokaliosiomis integralinėmis kraštinėmis sąlygomis sprendimas kintamųjų krypčių metodu. Uždavinio sprendinys randamas papildomai išsprendžiant neaukštos eilės algebrinę tiesinių lygčių sistemą, kuri sudaroma panaudojant nelokaliąsias integralines sąlygas. Išanalizuota skirtuminio operatoriaus su nelokaliosiomis sąlygomis spektro struktūra. Spektro struktūra išanalizuota tuo tikslu, kad galima būtų išnagrinėti dvimačio parabolinio uždavinio su viena nelokaliąja integraline sąlyga sprendžiamo kintamųjų krypčių ar lokaliai vienmačiu metodu, stabilumą. Nustatyta nelokaliosios sąlygos įtaka spektro struktūrai. Sudarytas elipsinio uždavinio su papildoma nelokaliąja sąlyga sprendimo algoritmas.

Magistro darbe yra tiriama parabolinės lygties su nelokaliąja integraline Robino sąlyga skirtuminė schema. Skirtuminės schemos stabilumui nagrinėti naudojama skirtuminio operatoriaus su nelokaliąja sąlyga spektro struktūros tyrimo metodika bei Maple programa, skirta kompiuteriniams eksperimentams atlikti. Atlikto magistro darbo rezultatai papildo iki šiol kitų mokslininkų gautus rezultatus tiriant parabolinių lygčių su nelokaliosiomis sąlygomis išreikštinių skirtuminių schemų tyrimus. Magistro darbą sudaro: įvadas, šešios pagrindinės dalys bei išvados. Įvadiniame skyriuje aptariamas temos aktualumas ir darbo tikslas, nurodomi naudojami tyrimo metodai. Antrajame ir trečiajame skyriuose suformuluojama parabolinės lygties su nelokaliąja integraline Robino išreikštinė skirtuminė schema bei jos pakankamoji stabilumo sąlyga. Ketvirtajame, penktajame ir šeštajame skyriuose randamas išreikštinės schemos stabilumas įvairiais atvejais bei pateikiama gautų rezultatų analizė. Septintajame skyriuje atliktas skaitinis eksperimentas. Pateikiamos viso darbo bendrosios išvados. / In the master work, explicit difference scheme for parabolic equation with nonlocal integral Robin condition, is considered. Stability condition of difference scheme is used to examine spectrum structure of differential operator with nonlocal condition and software of Maple, which perform of sacred to the computer experiment. My the master work extends and suplements the results of other scientists in analysis for explicit difference scheme for parabolic equation with nonlocal conditions. The master work consists of the introduction, six chapters and the conclusions. In the introduction the topicality of the problem and object of work are defined, also methods of analysis is presented. In the second and third chapters, explicit difference scheme for parabolic equation with nonlocal integral Robin condition is formulated and also the sufficient stability condition of the difference sheme. In the fourth, fifth and the sixth chapters the stability explicit difference scheme is considered and analysis the results is presented. In the seventh chapter the numerical experiment is used. The conlusions are presented.