Focaliser sur:
Tous les jours
21 mai 2018
22 mai 2018
23 mai 2018
Indico style
Indico style - inline minutes
Indico style - numbered
Indico style - numbered + minutes
Indico Weeks View
Retour à l'affichage de la conférence
Choisissez le fuseau horaire
Utiliser le fuseau horaire de l'événement/catégorie
Veuillez spécifier un fuseau horaire
Africa/Abidjan
Africa/Accra
Africa/Addis_Ababa
Africa/Algiers
Africa/Asmara
Africa/Bamako
Africa/Bangui
Africa/Banjul
Africa/Bissau
Africa/Blantyre
Africa/Brazzaville
Africa/Bujumbura
Africa/Cairo
Africa/Casablanca
Africa/Ceuta
Africa/Conakry
Africa/Dakar
Africa/Dar_es_Salaam
Africa/Djibouti
Africa/Douala
Africa/El_Aaiun
Africa/Freetown
Africa/Gaborone
Africa/Harare
Africa/Johannesburg
Africa/Juba
Africa/Kampala
Africa/Khartoum
Africa/Kigali
Africa/Kinshasa
Africa/Lagos
Africa/Libreville
Africa/Lome
Africa/Luanda
Africa/Lubumbashi
Africa/Lusaka
Africa/Malabo
Africa/Maputo
Africa/Maseru
Africa/Mbabane
Africa/Mogadishu
Africa/Monrovia
Africa/Nairobi
Africa/Ndjamena
Africa/Niamey
Africa/Nouakchott
Africa/Ouagadougou
Africa/Porto-Novo
Africa/Sao_Tome
Africa/Tripoli
Africa/Tunis
Africa/Windhoek
America/Adak
America/Anchorage
America/Anguilla
America/Antigua
America/Araguaina
America/Argentina/Buenos_Aires
America/Argentina/Catamarca
America/Argentina/Cordoba
America/Argentina/Jujuy
America/Argentina/La_Rioja
America/Argentina/Mendoza
America/Argentina/Rio_Gallegos
America/Argentina/Salta
America/Argentina/San_Juan
America/Argentina/San_Luis
America/Argentina/Tucuman
America/Argentina/Ushuaia
America/Aruba
America/Asuncion
America/Atikokan
America/Bahia
America/Bahia_Banderas
America/Barbados
America/Belem
America/Belize
America/Blanc-Sablon
America/Boa_Vista
America/Bogota
America/Boise
America/Cambridge_Bay
America/Campo_Grande
America/Cancun
America/Caracas
America/Cayenne
America/Cayman
America/Chicago
America/Chihuahua
America/Ciudad_Juarez
America/Costa_Rica
America/Creston
America/Cuiaba
America/Curacao
America/Danmarkshavn
America/Dawson
America/Dawson_Creek
America/Denver
America/Detroit
America/Dominica
America/Edmonton
America/Eirunepe
America/El_Salvador
America/Fort_Nelson
America/Fortaleza
America/Glace_Bay
America/Goose_Bay
America/Grand_Turk
America/Grenada
America/Guadeloupe
America/Guatemala
America/Guayaquil
America/Guyana
America/Halifax
America/Havana
America/Hermosillo
America/Indiana/Indianapolis
America/Indiana/Knox
America/Indiana/Marengo
America/Indiana/Petersburg
America/Indiana/Tell_City
America/Indiana/Vevay
America/Indiana/Vincennes
America/Indiana/Winamac
America/Inuvik
America/Iqaluit
America/Jamaica
America/Juneau
America/Kentucky/Louisville
America/Kentucky/Monticello
America/Kralendijk
America/La_Paz
America/Lima
America/Los_Angeles
America/Lower_Princes
America/Maceio
America/Managua
America/Manaus
America/Marigot
America/Martinique
America/Matamoros
America/Mazatlan
America/Menominee
America/Merida
America/Metlakatla
America/Mexico_City
America/Miquelon
America/Moncton
America/Monterrey
America/Montevideo
America/Montserrat
America/Nassau
America/New_York
America/Nome
America/Noronha
America/North_Dakota/Beulah
America/North_Dakota/Center
America/North_Dakota/New_Salem
America/Nuuk
America/Ojinaga
America/Panama
America/Paramaribo
America/Phoenix
America/Port-au-Prince
America/Port_of_Spain
America/Porto_Velho
America/Puerto_Rico
America/Punta_Arenas
America/Rankin_Inlet
America/Recife
America/Regina
America/Resolute
America/Rio_Branco
America/Santarem
America/Santiago
America/Santo_Domingo
America/Sao_Paulo
America/Scoresbysund
America/Sitka
America/St_Barthelemy
America/St_Johns
America/St_Kitts
America/St_Lucia
America/St_Thomas
America/St_Vincent
America/Swift_Current
America/Tegucigalpa
America/Thule
America/Tijuana
America/Toronto
America/Tortola
America/Vancouver
America/Whitehorse
America/Winnipeg
America/Yakutat
Antarctica/Casey
Antarctica/Davis
Antarctica/DumontDUrville
Antarctica/Macquarie
Antarctica/Mawson
Antarctica/McMurdo
Antarctica/Palmer
Antarctica/Rothera
Antarctica/Syowa
Antarctica/Troll
Antarctica/Vostok
Arctic/Longyearbyen
Asia/Aden
Asia/Almaty
Asia/Amman
Asia/Anadyr
Asia/Aqtau
Asia/Aqtobe
Asia/Ashgabat
Asia/Atyrau
Asia/Baghdad
Asia/Bahrain
Asia/Baku
Asia/Bangkok
Asia/Barnaul
Asia/Beirut
Asia/Bishkek
Asia/Brunei
Asia/Chita
Asia/Choibalsan
Asia/Colombo
Asia/Damascus
Asia/Dhaka
Asia/Dili
Asia/Dubai
Asia/Dushanbe
Asia/Famagusta
Asia/Gaza
Asia/Hebron
Asia/Ho_Chi_Minh
Asia/Hong_Kong
Asia/Hovd
Asia/Irkutsk
Asia/Jakarta
Asia/Jayapura
Asia/Jerusalem
Asia/Kabul
Asia/Kamchatka
Asia/Karachi
Asia/Kathmandu
Asia/Khandyga
Asia/Kolkata
Asia/Krasnoyarsk
Asia/Kuala_Lumpur
Asia/Kuching
Asia/Kuwait
Asia/Macau
Asia/Magadan
Asia/Makassar
Asia/Manila
Asia/Muscat
Asia/Nicosia
Asia/Novokuznetsk
Asia/Novosibirsk
Asia/Omsk
Asia/Oral
Asia/Phnom_Penh
Asia/Pontianak
Asia/Pyongyang
Asia/Qatar
Asia/Qostanay
Asia/Qyzylorda
Asia/Riyadh
Asia/Sakhalin
Asia/Samarkand
Asia/Seoul
Asia/Shanghai
Asia/Singapore
Asia/Srednekolymsk
Asia/Taipei
Asia/Tashkent
Asia/Tbilisi
Asia/Tehran
Asia/Thimphu
Asia/Tokyo
Asia/Tomsk
Asia/Ulaanbaatar
Asia/Urumqi
Asia/Ust-Nera
Asia/Vientiane
Asia/Vladivostok
Asia/Yakutsk
Asia/Yangon
Asia/Yekaterinburg
Asia/Yerevan
Atlantic/Azores
Atlantic/Bermuda
Atlantic/Canary
Atlantic/Cape_Verde
Atlantic/Faroe
Atlantic/Madeira
Atlantic/Reykjavik
Atlantic/South_Georgia
Atlantic/St_Helena
Atlantic/Stanley
Australia/Adelaide
Australia/Brisbane
Australia/Broken_Hill
Australia/Darwin
Australia/Eucla
Australia/Hobart
Australia/Lindeman
Australia/Lord_Howe
Australia/Melbourne
Australia/Perth
Australia/Sydney
Canada/Atlantic
Canada/Central
Canada/Eastern
Canada/Mountain
Canada/Newfoundland
Canada/Pacific
Europe/Amsterdam
Europe/Andorra
Europe/Astrakhan
Europe/Athens
Europe/Belgrade
Europe/Berlin
Europe/Bratislava
Europe/Brussels
Europe/Bucharest
Europe/Budapest
Europe/Busingen
Europe/Chisinau
Europe/Copenhagen
Europe/Dublin
Europe/Gibraltar
Europe/Guernsey
Europe/Helsinki
Europe/Isle_of_Man
Europe/Istanbul
Europe/Jersey
Europe/Kaliningrad
Europe/Kirov
Europe/Kyiv
Europe/Lisbon
Europe/Ljubljana
Europe/London
Europe/Luxembourg
Europe/Madrid
Europe/Malta
Europe/Mariehamn
Europe/Minsk
Europe/Monaco
Europe/Moscow
Europe/Oslo
Europe/Paris
Europe/Podgorica
Europe/Prague
Europe/Riga
Europe/Rome
Europe/Samara
Europe/San_Marino
Europe/Sarajevo
Europe/Saratov
Europe/Simferopol
Europe/Skopje
Europe/Sofia
Europe/Stockholm
Europe/Tallinn
Europe/Tirane
Europe/Ulyanovsk
Europe/Vaduz
Europe/Vatican
Europe/Vienna
Europe/Vilnius
Europe/Volgograd
Europe/Warsaw
Europe/Zagreb
Europe/Zurich
GMT
Indian/Antananarivo
Indian/Chagos
Indian/Christmas
Indian/Cocos
Indian/Comoro
Indian/Kerguelen
Indian/Mahe
Indian/Maldives
Indian/Mauritius
Indian/Mayotte
Indian/Reunion
Pacific/Apia
Pacific/Auckland
Pacific/Bougainville
Pacific/Chatham
Pacific/Chuuk
Pacific/Easter
Pacific/Efate
Pacific/Fakaofo
Pacific/Fiji
Pacific/Funafuti
Pacific/Galapagos
Pacific/Gambier
Pacific/Guadalcanal
Pacific/Guam
Pacific/Honolulu
Pacific/Kanton
Pacific/Kiritimati
Pacific/Kosrae
Pacific/Kwajalein
Pacific/Majuro
Pacific/Marquesas
Pacific/Midway
Pacific/Nauru
Pacific/Niue
Pacific/Norfolk
Pacific/Noumea
Pacific/Pago_Pago
Pacific/Palau
Pacific/Pitcairn
Pacific/Pohnpei
Pacific/Port_Moresby
Pacific/Rarotonga
Pacific/Saipan
Pacific/Tahiti
Pacific/Tarawa
Pacific/Tongatapu
Pacific/Wake
Pacific/Wallis
US/Alaska
US/Arizona
US/Central
US/Eastern
US/Hawaii
US/Mountain
US/Pacific
UTC
Sauver
Europe/Bucharest
Français
Deutsch (Deutschland)
English (United Kingdom)
English (United States)
Español (España)
Français (France)
Italiano (Italia)
Polski (Polska)
Português (Brasil)
Türkçe (Türkiye)
Čeština (Česko)
Монгол (Монгол)
Українська (Україна)
中文 (中国)
S'authentifier
Analyse, analyse numérique et contrôle des milieux continus
de
lundi 21 mai 2018 (08:00)
à
mercredi 23 mai 2018 (18:00)
lundi 21 mai 2018
08:45
Ouverture - Discours de bienvenue
Ouverture - Discours de bienvenue
08:45 - 09:00
Room: salle 220
09:00
Equations nonlinéaires stochastiques du type Fokker-Planck
-
Viorel Barbu
(
Académie Roumaine, Iași, Roumanie
)
Equations nonlinéaires stochastiques du type Fokker-Planck
Viorel Barbu
(
Académie Roumaine, Iași, Roumanie
)
09:00 - 10:00
On étudie l'existence et l'unicité d'une équation nonlinéaire Fokker-Planck perturbée par un processus Gaussien multiplicatif. Les résultats présentés ici ont été obtenus en collaboration avec Michael Röckner (Université de Bielefeld).
10:00
Comportement asymptotique des équations de convection-diffusion fractionnaires / Asymptotic behaviour for fractional diffusion-convection equations
-
Liviu Ignat
(
IMAR, Bucarest, Roumanie
)
Comportement asymptotique des équations de convection-diffusion fractionnaires / Asymptotic behaviour for fractional diffusion-convection equations
Liviu Ignat
(
IMAR, Bucarest, Roumanie
)
10:00 - 11:00
In this talk, we analyze the long time behaviour of the solutions of the equation $ u_t(t,x)+(-\Delta) ^{\alpha/2}u(t,x)+(f(u))_x=0,\ t\in (0,\infty),\ x\in\mathbf{R},$ where $\alpha\in (0,2)$ and $f(s)=|s|^{q-1}s/q$ with $q\in (1,\infty)$. We present some prvious results on the asymptotic expansion of the solutions when the time goes to infinity. We prove that in the one-dimensional case, for $q\in (1,\alpha)$ the asymptotic behaviour is given by the entropy solution of the conservation law $u_t(t,x)+(f(u))_x=0$, $u(0)=M\delta_0$ where $M$ is the mass of the initial data. The proof relies on tricky inequalities to guarantee an Oleinik type inequality $(u^{q-1})_x\leq 1/t$. This is a joint work with Diana Stan. This presentation is partially supported by CNCS-UEFISCDI No. PN-III-P4- ID-PCE-2016-0035.
11:00
pause café
pause café
11:00 - 11:30
11:30
Contrôlabilité d’une équation à diffusion anormale/Controllability of an anomalous diffusion equation
-
Sorin Micu
(
U. Craiova, Roumanie
)
Contrôlabilité d’une équation à diffusion anormale/Controllability of an anomalous diffusion equation
Sorin Micu
(
U. Craiova, Roumanie
)
11:30 - 12:30
Many physical phenomena are characterized by an anomalous diffusion when the mean square displacement of a particle will grow at a nonlinear rate in time. Some typical examples are the subdiffusional mobility of the proteic macromolecules in overcrowded cellular cytoplasm [3] and the smoke's superdiffusion in turbulent atmosphere [2]. <br> We consider a simple one dimensional linear model which describes an anomalous diffusive behavior, involving a fractional Laplace operator, and we study its controllability property. If the fractional power of the Laplace operator is less or equal than $\frac{1}{2}$, the system is not spectrally controllable [1]. <br> The aim of the paper is twofold. Firstly, to analyze the possibility of controlling a finite number $N$ of eigenmodes of the solution and to find the behavior of the corresponding controls when $N$ tends to infinity. Secondly, to investigate the null-controllability property of the system when the support of the control moves linearly with respect to time. <br><br> [1] Sorin Micu and Enrique Zuazua, <em> On the controllability of a fractional order parabolic equation</em>, SIAM J. Control Optim. 44 (2006), 1950-1972.<br> [2] Michael F.Shlesinger, Joseph Klafter and Bruce J. West, <em> Levy walks with applications to turbulence and chaos</em>, Physica A: Statistical Mechanics and its Applications 140 (1986), 212-218.<br> [3] Matthias Weiss, Markus Elsner, Fredrik Kartberg and Tommy Nilsson, <em> Anomalous Subdiffusion Is a Measure for Cytoplasmic Crowding in Living Cells</em>, Biophysical Journal 87 (2004), 3518-3524.<br>
12:45
déjeuner
déjeuner
12:45 - 13:45
14:00
Quelques méthodes récentes pour l'étude du système de Navier-Stokes à densité discontinue / Recent approaches for the study of the Navier-Stokes equations with discontinuous density
-
Raphaël Danchin
(
U. Paris-Est , Créteil, France
)
Quelques méthodes récentes pour l'étude du système de Navier-Stokes à densité discontinue / Recent approaches for the study of the Navier-Stokes equations with discontinuous density
Raphaël Danchin
(
U. Paris-Est , Créteil, France
)
14:00 - 15:00
The inhomogeneous incompressible Navier-Stokes equations that govern the evolution of viscous incompressible flows with non-constant density have received a lot of attention lately. In this talk, we shall focus on the singular situation where the density is discontinuous, which is in particular relevant for describing the evolution of a mixture of two incompressible and non reacting fluids with constant density, or of a drop of liquid in vacuum.
15:00
Sur les stabilités localisées de type onde-courte de certains écoulements géophysiques / On the short-wavelength stabilities of some geophysical flows
-
Delia Ionescu-Kruse
(
IMAR, Bucarest, Roumanie
)
Sur les stabilités localisées de type onde-courte de certains écoulements géophysiques / On the short-wavelength stabilities of some geophysical flows
Delia Ionescu-Kruse
(
IMAR, Bucarest, Roumanie
)
15:00 - 16:00
This talk is a survey of the short-wavelength stability method for rotating flows. This method is applied to the specific study of some exact geophysical flows. For Gerstner-like geophysical flows one can identify perturbations in certain directions as a source of instabilities with an exponentially growing amplitude, the growth rate of the instabilities depending on the steepness of the travelling wave profile. On the other hand, for certain physically realistic velocity profiles, steady flows moving only in the azimuthal direction, with no variation in this direction, are locally stable to the short-wavelength perturbations…..
16:00
pause café
pause café
16:00 - 16:30
16:30
Large-amplitude steady gravity water waves with constant vorticity
-
Eugen Vărvăruca
(
U. Alexandru Ioan Cuza, Iași, Roumanie
)
Large-amplitude steady gravity water waves with constant vorticity
Eugen Vărvăruca
(
U. Alexandru Ioan Cuza, Iași, Roumanie
)
16:30 - 17:30
We consider the problem of two-dimensional travelling water waves propagating under the influence of gravity in a flow of constant vorticity over a flat bed. By using a conformal mapping from a strip onto the fluid domain, the governing equations are recasted as a one-dimensional pseudodifferential equation that generalizes Babenko's equation for irrotational waves of infinite depth. We explain how an application of the theory of global bifurcation in the real-analytic setting leads to the existence of families of waves of large amplitude that may have critical layers and/or overhanging profiles. Some new a priori bounds and geometric properties of the solutions on the global bifurcating branches will also be presented. This is joint work with Adrian Constantin (University of Vienna, Austria) and Walter Strauss (Brown University, USA).
19:30
Banquet
Banquet
19:30 - 22:30
Room: Restaurant Zexe - Strada Icoanei 80
mardi 22 mai 2018
09:00
Anneaux tourbillonnaires visqueux
-
Thierry Gallay
(
U. Grenoble-Alpes, France
)
Anneaux tourbillonnaires visqueux
Thierry Gallay
(
U. Grenoble-Alpes, France
)
09:00 - 10:00
Un anneau tourbillonnaire est un écoulement dans lequel les lignes de tourbillon remplissent un tore plein, qui se déplace à vitesse constante le long de son axe de symétrie. Des écoulements de ce genre se rencontrent fréquemment dans la nature, et paraissent remarquablement stables. Pour l'équation d'Euler incompressible à symétrie cylindrique, on peut d'ailleurs en construire par des méthodes variationnelles. Dans cet exposé, on considère le cas d'un fluide visqueux et on montre que les équations de Navier-Stokes incompressibles à symétrie cylindrique sont globalement bien posées lorsque la donnée initiale est un filament tourbillonnaire, c'est-à-dire quand le tourbillon initial est une mesure vectorielle supportée par un cercle. Il s'agit d'un résultat obtenu en collaboration avec Vladimir Sverak (Minneapolis).
10:00
Quelques propriétés des schémas AP (Préservant l'Asymptotique).
-
Claudia Negulescu
(
U. Paul Sabatier, Toulouse, France
)
Quelques propriétés des schémas AP (Préservant l'Asymptotique).
Claudia Negulescu
(
U. Paul Sabatier, Toulouse, France
)
10:00 - 11:00
Les problèmes multi-échelles (contenant des échelles disparates en espace et temps) sont très fréquents dans la nature et difficiles à traiter d'un point de vue théorique ainsi que numérique. Je vais présenter dans cet exposé une nouvelle approche pour une résolution efficace d'un problème d'évolution contenant un terme de transport raid. Il s'agit d'une approche préservant l'asymptotique, quand le paramètre de raideur tend vers zéro, technique désignée "AP-method". Cette méthode sera aussi comparée avec des méthodes plus traditionnelles, implicites-explicites (IMEX-methods). L'application visée vient de la description cinétique (équation de Boltzmann, Fokker-Planck, Vlasov) des plasmas thermonucléaires, confinés par un très fort champ magnétique.
11:00
pause café
pause café
11:00 - 11:30
11:30
Courbure moyenne dans l’espace de Minkowski/Mean curvature in Minkowski space
-
Cristian Bereanu
(
U. de Bucarest, Roumanie
)
Courbure moyenne dans l’espace de Minkowski/Mean curvature in Minkowski space
Cristian Bereanu
(
U. de Bucarest, Roumanie
)
11:30 - 12:30
In this talk I will survey some results about boundary value problems (Dirichlet and Neumann) associated to nonlinear perturbations of the mean curvature in Minkowski space. Nonsmooth critical point theory and Leray -Schauder degree are the main tools in our proofs.
12:45
déjeuner
déjeuner
12:45 - 13:45
14:00
Stabilisation feedback d'un système de transition de phase avec effets de viscosité
-
Gabriela Marinoschi
(
ISMMA, Bucarest, Roumanie
)
Stabilisation feedback d'un système de transition de phase avec effets de viscosité
Gabriela Marinoschi
(
ISMMA, Bucarest, Roumanie
)
14:00 - 15:00
On présente la stabilisation feedback d'un système de transition de phase de type Cahn-Hilliard avec des effets de viscosité dans l'équation pour la phase, en utilisant un contrôle feedback avec support dans un sous-ensemble du domaine. La technique est basée sur la construction du contrôle comme une combinaison linéaire des modes instables du système linéarisé correspondant, suivie par sa représentation sous forme feedback au moyen d'une méthode d'optimisation. Les résultats sont fournis à la fois pour un potentiel régulier dans l'équation de phase (le double potentiel) et pour un potentiel singulier de type logarithmique. Le cas limite lorsque la viscosité tend vers zéro est également présenté.
15:00
Méthodes de contrôle optimal en optimisation de forme / Optimal Control Methods in shape Optimization
-
Dan Tiba
(
IMAR, Bucarest, Roumanie
)
Méthodes de contrôle optimal en optimisation de forme / Optimal Control Methods in shape Optimization
Dan Tiba
(
IMAR, Bucarest, Roumanie
)
15:00 - 16:00
A typical example of shape optimization problems has the form: $ \mathop{\rm Min}\limits_{\Omega \in \mathcal{O}} \int_{\Lambda} j (x, y_{\Omega}(x), \nabla y_{\Omega} (x)) dx, $ $ - \Delta y_{{\Omega}} = f \quad in \; \Omega, $ $ y_{\Omega} = 0 \quad on \; \partial\Omega $ with other supplementary constraints (on $y, \Omega$, etc.), if necessary. Here, $\Omega \subset D$ is an (unknown) domain, $D$ is some given bounded Lipschitzian domain, $f \in L^2(D) $, $j(.,.,.) $ is a Caratheodory mapping and $\Lambda$ is either $\Omega$ or some fixed subdomain $E \subset D$. Let me also mention that many geometric optimization problems arising in mechanics (for plates, beams, arches, curved rods or shells), are expressed, as well, as optimal control problems by the coefficients, due to the special form of their models. This point is not discussed here. The presentation will discuss in detail two cases: optimization of a plate with holes and a penalization approach to a general shape optimization problem. Boundary observation problems will also be presented if time allows. An essential ingredient in these developments is the implicit parametrization method that allows an advantageous description of implicitly defined manifolds via iterated Hamiltonian systems.
16:00
pause café
pause café
16:00 - 16:30
16:30
Zero entropic relaxation time for a ferromagnetic fluid system
-
Stefano Scrobogna
(
Centre Basque de Mathématiques Appliqueées, Bilbao, Espagne
)
Zero entropic relaxation time for a ferromagnetic fluid system
Stefano Scrobogna
(
Centre Basque de Mathématiques Appliqueées, Bilbao, Espagne
)
16:30 - 17:30
In the physical sciences, relaxation usually means the return of a perturbed system to equilibrium. Each relaxation process can be categorized by a relaxation time $\tau$, for a generic commercial grade ferrofluid (a mixture of nanoscale ferromagnetic particles of a compound containing iron suspended in a fluid) the relaxation time is very small, of the order $\tau \approx 10^{-9}$; it makes hence sense to provide an asymptotic approximation when $\tau \to 0$. In this talk I will explain how to construct solutions for the Shliomis model of ferrofluids in a critical space of infinite $L^2$ energy uniformly for $\tau\in \left(0, \tau_0\right)$, such uniform construction will allow us to study the limit regime $\tau \to 0$ and the convergence of the critical solutions.
mercredi 23 mai 2018
09:00
Contrôlabilité de systèmes paraboliques continus et discrets
-
Franck Boyer
(
U. Paul Sabatier, Toulouse, France
)
Contrôlabilité de systèmes paraboliques continus et discrets
Franck Boyer
(
U. Paul Sabatier, Toulouse, France
)
09:00 - 10:00
Dans cet exposé, je présenterai quelques résultats concernant les propriétés de contrôlabilité à zéro de systèmes paraboliques couplés et de leurs discrétisations. Je considérerai en particulier le cas où il y a moins de contrôles que d'équations, ce qui peut engendrer, en fonction de la structure des termes de couplage, des phénomènes inattendus comme des conditions géométriques de contrôle ou des temps minimaux de contrôle.
10:00
Systèmes paraboliques, stabilisation et propriétés d'unique continuation/Parabolic systems, stabilization and unique continuation properties
-
Cătălin-George Lefter
(
U. Alexandru Ioan Cuza, Iași, Roumanie
)
Systèmes paraboliques, stabilisation et propriétés d'unique continuation/Parabolic systems, stabilization and unique continuation properties
Cătălin-George Lefter
(
U. Alexandru Ioan Cuza, Iași, Roumanie
)
10:00 - 11:00
On considère des systèmes paraboliques sémi-linéaires contrôlés et on étudie la stabilisation feedback avec contrôles supportés dans un sous-domaine. On s'intéresse du cas ou on a un seul contrôle qui agit simultanément dans les deux équations. L'approche est basée sur la contrôlabilité approchée du linéarisé et l'utilisation d'une norme issue d'une certaine équation de Lyapunov. On discute des applications aux équations de réaction-diffusion. <br> On s'intéresse aussi à l'étude de la continuation unique en utilisant des estimations de Carleman adéquates et aussi à la continuation unique au moment initial obtenue en termes de rate d'annulation dans un sous-domaine. <br> La première partie de l'exposé est basée sur un travail en collaboration avec Elena-Alexandra Melnig. <br><br> We consider controlled systems of semilinear parabolic equations and we study feedback stabilization with controls supported in a subdomain. We are interested in the situation when only one control acts simultaneously in both equation. The approach is based on approximate controllability for the linearized system and the use of an appropriate norm obtained from a Lyapunov equation. Applications to reaction diffusion systems are discussed. <br> We are also interested to the study of unique continuation by appropriate Carleman estimates and also to unique continuation at initial time obtained in terms of vanishing rate in a subdomain. <br> First part of the talk is based on a joint work with Elena-Alexandra Melnig.
11:00
pause café
pause café
11:00 - 11:30
11:30
Contrôlabilité à zéro de l’équation linéaire de Kuramoto-Sivashinsky sur des arbres étoilés /Null-controllability results for the linear Kuramoto-Sivashinsky equation on star-shaped trees
-
Cristian Cazacu
(
U. de Bucarest/ICUB & IMAR, Roumanie
)
Contrôlabilité à zéro de l’équation linéaire de Kuramoto-Sivashinsky sur des arbres étoilés /Null-controllability results for the linear Kuramoto-Sivashinsky equation on star-shaped trees
Cristian Cazacu
(
U. de Bucarest/ICUB & IMAR, Roumanie
)
11:30 - 12:30
In this talk we discuss null-controllability properties for the linear Kuramoto-Sivashinsky equation on a star-shaped tree with two types of boundary conditions, with boundary controls acting on the external vertices of the tree. Roughly speaking, we show that with few exceptions (when the so-called anti-diffusion parameter belongs to a countable critical set) at any positive time the system is null-controllable when acting with controls on a part of the external vertices. We point out that the critical set for which the null-controllability fails differs from the first model to the second one. <br><br> This is a joint work with Liviu Ignat (``Simion Stoilow" Institute of Mathematics of the Romanian Academy, Romania) and Ademir Pazoto (Universidade Federal do Rio de Janeiro, Brasil). <br><br> Partially supported by a Young Researchers Grant awarded by ICUB (The Research Institute of the University of Bucharest) and CNCS-UEFISCDI Grant No. PN-III-P4-ID-PCE-2016-0035.