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BEGIN:VEVENT
SUMMARY:Fast Kinetic Monte Carlo Methods for Novel Solar Cell Design
DTSTART:20180710T070000Z
DTEND:20180710T073000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1740@indico.math.cnrs.fr
DESCRIPTION:Speakers: Tan Trung NGUYEN (Department of Mathematical Science
s Bath University)\n\nThis is a joint work with A. Walker\, R. Scheichl an
d C.A. Yates\, Bath University\n\nKinetic Monte Carlo (KMC) methods [1] ar
e widely used to simulate the surface adsorption\, diffusion\,\ngrowth\, s
tatistical physics\, radiation damage annealing\, bioglogical systems\, am
ongst other applications\nby evolving systems dynamically from state to st
ate. In our application to solar cells\, KMC are required\nto predict devi
ce behaviour from the material properties at the microscopic scale. Our wo
rk has mainly\nfocussed on atomistic studies of the microscopic processes\
, such as charge and exciton hopping\, recombination rates and light absor
ption. Using the parameters obtained from the atomistic simulations\, we f
ocus on KMC simulations at the mesoscale\, computing current-voltage chara
cteristics\, charge mobilities and parameters for calculating recombinatio
n that subsequently feed into faster device design offered by continuum mo
dels where current-voltage characteristics are obtained.\n\nThe KMC method
is equivalent to the Gillespie algorithm [2] which simulates the trajecto
ries consistent\nwith the “exact” dynamical evolution of a system. The
advantage of KMC method is the probability that\nwe see a given sequence
of states and transition times is the same as the probability for seeing t
hat same trajectory in the molecular dynamics which is much more expensive
since one propagates equations of motion forward in time. However\, the c
omputational cost is still very high in many practical applications such a
s solar cell design\, bioglogical systems.\n\nIn order to accelerate atomi
stic simulations\, we apply the idea of multilevel Monte Carlo (MLMC)\nmet
hods [3] to reduce the computational time significantly but still retain t
he accuracy based on controlling statistical errors. The first results we
have obtained with r-leaping and tau-leaping show the efficiency when skip
ping expensive computations such as the update of the electrostatic potent
ial (the most expensive) and propensity functions in such a way that the s
tatistical errors are still acceptable (less than 10%).\nIn particular for
solar cell designs\, this development will be coupled with fast and massi
vely parallel Poisson solvers for the modelling of long-range interactions
.\n\n[1] U. Neupane\, B. Bahrami\, M. Biesecker\, and Baroughi M.F. Kineti
c monte carlo modeling on organic\nsolar cells: Domain size\, donor-accept
or ratio and thickness. Nano Energy\, 81:128–137\, 2017.\n\n[2] D.T. Gil
lespi. Exact stochastic simulation of coupled chemical reactions. Journal
of Physical Chemistry\, 81(25)\, 1977.\n\n[3] C. Lester\, R.E. Baker\, M.B
. Giles\, and Yates C.A. Extending the multi-level method for the simulati
on\nof stochastic biological systems. Bull Math Biol\, 2016\n\nhttps://ind
ico.math.cnrs.fr/event/3023/contributions/1740/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1740/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Posteriori Error Estimation for Transport Equations
DTSTART:20180710T083000Z
DTEND:20180710T090000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1739@indico.math.cnrs.fr
DESCRIPTION:Speakers: Anh Ha LE (University of science\, VNU-HCMUS)\n\nIn
this paper\, we will consider a posteriori error estimation for the transp
ort equation $\\partial_t u+\\mathbf{a}(x\,t)\\cdot\\nabla u=0$ with the i
nitial data $u_0\\in L^\\infty\\cap BV_{{\\rm loc}}$ and the divergence of
the velocity field $\\mathbf{a}$ is not equal to zero. An a posteriori es
timate for the error between the exact solution and the solution of an upw
ind finite volume scheme is derived in the $L^1$ norm.\n\nhttps://indico.m
ath.cnrs.fr/event/3023/contributions/1739/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1739/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tangential gradient in a sub-gradient diffusion equation
DTSTART:20180710T074500Z
DTEND:20180710T081500Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1746@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Nguyet Nga TA (University of science\, VNU-HCMUS
)\n\nWe study stationary equation governed by the operator $ -\\nabla \\cd
ot A(x\, \\nabla u) =\n\\mu$ in the case where $A(x\, \\xi)$ is a maximal
monotone graph and $\\mu$ is a Radon measure. Our main interest concerns
the typical situation where $A(x\, .)$ is defined only in a bounded region
of $\\mathbf{R}^n$\; so that $A(x\, .)$ does not satisfies the standard p
olynomial growth control condition. The natural energy space in this case
is the space of Lipschitz continuous function and the flux is a vector val
ued measure. We using tangential gradient with respect to a Radon measure
to pass through this difficulty.\n\nhttps://indico.math.cnrs.fr/event/3023
/contributions/1746/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1746/
END:VEVENT
BEGIN:VEVENT
SUMMARY:OASIS: An Active Framework for Set Inversion
DTSTART:20180710T083000Z
DTEND:20180710T090000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1745@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thanh Binh NGUYEN (University of science\, VNU-HCMUS
)\n\nIn this work\, we introduce a novel method for solving the set invers
ion problem by formulating it as a binary classification problem. Aiming t
o develop a fast algorithm that can work effectively with high-dimensional
and computation- ally expensive nonlinear models\, we focus on active lea
rning\, a family of new and powerful techniques which can achieve the same
level of accuracy with fewer data points compared to traditional learning
methods. Specifically\, we propose OASIS\, an active learning framework u
sing Support Vector Machine algorithms for solving the problem of set inve
rsion. Our method works well in high dimensions and its computational cost
is relatively robust to the increase of dimension. We illustrate the perf
ormance of OASIS by several simulation studies and show that our algorithm
outperforms VISIA\, the state-of-the-art method.\n\nhttps://indico.math.c
nrs.fr/event/3023/contributions/1745/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1745/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Likelihood in the Symbolic Context
DTSTART:20180711T020000Z
DTEND:20180711T030000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1749@indico.math.cnrs.fr
DESCRIPTION:Speakers: Richard EMILION (Mathématiques – Analysie\, Proba
bilités\, Modélisation\, Université d’Orléans\, France.)\n\nOur cont
ext is the statistic of a random distribution\, that is a random variable
taking values in a space of probability measures. Such a context is useful
when dealing with classes of raw data of a large dataset or with objects
having a complex behaviour. \nWe present the theoretical framework\, some
examples of models\, the likelihood for finite dimensional estimators and
some recent applications.\n\nhttps://indico.math.cnrs.fr/event/3023/contr
ibutions/1749/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1749/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Some hope for the Buridan’s donkey… and other stories
DTSTART:20180709T020000Z
DTEND:20180709T030000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1753@indico.math.cnrs.fr
DESCRIPTION:Speakers: Marc PEIGNE (Laboratoire de Mathématiques et Physiq
ue Théorique\, Faculté des Sciences et Techniques Université François
Rabelais\, France.)\n\nWe describe the asymptotic behavior of the Buridan
’s wandering using technics developed to study iterated Lipschitz functi
ons systems with possibly place dependent probabilities. Under some genera
l conditions on this family of probabilities and using quasi-compact linea
r operators technics\, we obtain a necessary and sufficient condition for
the uniqueness of the stationary probability measure for this chain and ex
plore the case when it does not hold\n\nhttps://indico.math.cnrs.fr/event/
3023/contributions/1753/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1753/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Choosing Subfields for LUOV and Field Lifting for Rainbow
DTSTART:20180709T074500Z
DTEND:20180709T081500Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1757@indico.math.cnrs.fr
DESCRIPTION:Speakers: Van Luyen LE (University of science\, VNU-HCMUS)
\n\nMultivariate public key cryptography (MPKC) is one of the main candida
tes for post-quantum cryptography. Rainbow\, an improved\n(multi-layer) ve
rsion of Unbalanced Oil and Vinegar (UOV)\, is one of the most famous mult
ivariate signature scheme that is a promising candidate for NIST standardi
zation. At INDOCRYPT 2017\, Beullens and Preneel introduced a new variant
LUOV of UOV. Their idea is to generate a UOV scheme over the binary field
$L= F_2$ and then lift it into a bigger field ${F}_{2^r}$ and hence drama
tically reduces the public key size.\n \nIn this talk\, we extend that
idea to Rainbow and theoretically yield the optimal choice for the subfiel
d $L$ over which a Rainbow is generated before being lifted to $K$. As a r
esult\, we can deduce the public key size to $37.5 \\%$.\n\nhttps://indico
.math.cnrs.fr/event/3023/contributions/1757/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1757/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Domain decomposition-based nonlinear preconditioning for elliptic
PDEs
DTSTART:20180711T030000Z
DTEND:20180711T040000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1751@indico.math.cnrs.fr
DESCRIPTION:Speakers: Felix KWOK (Department of Mathematics\, Hong Kong Ba
ptist University\, Hong Kong felix_kwok@hkbu.edu.hk)\n\nOne way to acceler
ate the numerical solution of a nonlinear elliptic problem is to use nonli
near preconditioning\, which replaces the original discretized problem by
an equivalent but easier one. In this talk\, we discuss how a fixed point
iteration for a nonlinear system can be used in combination of Newton's me
thod to yield highly efficient\, nonlinearly preconditioned methods. Our s
tarting point is the Restricted Additive Schwarz Preconditioned Exact Newt
on (RASPEN) method by Dolean et al.~(2016)\, which is derived from the non
linear Restricted Additive Schwarz method. We then show how to extend this
method to include a coarse component\, as well as how to incorporate opti
mized transmission conditions of the Robin type. Finally\, we will show so
me applications demonstrating the effectiveness of our approach.\n\nhttps:
//indico.math.cnrs.fr/event/3023/contributions/1751/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1751/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Long-time asymptotic expansions for decaying solutions of Navier-S
tokes equations
DTSTART:20180709T070000Z
DTEND:20180709T073000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1759@indico.math.cnrs.fr
DESCRIPTION:Speakers: Tien Dat CAO (Texas Tech University)\n\nWe study the
large time behavior of solutions to the three-dimensional Navier-Stokes e
quations with periodic boundary conditions. It is shown that if the force
has an asymptotic expansion\, as time tends to infinity\, with respect to
certain families of decaying functions in Sobolev-Gevrey space\, then any
weak solution admits an asymptotic expansion of the same type. In particul
ar\, we establish the expansions in terms of power decaying functions and
the $\\log$ or $\\log(\\log)$ decaying ones. This is a joint work with Lua
n Hoang (Texas Tech University).\n\nhttps://indico.math.cnrs.fr/event/3023
/contributions/1759/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1759/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Iterated methods for non-monotone quasi-equilibrium problems
DTSTART:20180709T084500Z
DTEND:20180709T091500Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1764@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Thu Van NGUYEN (University of science\, VNU-HCMU
S)\n\nIn this talk a quasi-equilibrium problem with a nonmonotone bifuncti
on is considered in a finite dimensional space. This is a kind of equilibr
ium problem in sense of Blum and Oettli\, or also called Ky Fan inequality
\, with a constraint set depending on the current point. An extragradient-
type method is presented and analyzed for its solution. The convergence of
the method is proved under the assumption that the solution set of an ass
ociated dual equilibrium problem is nonempty.\n\nhttps://indico.math.cnrs
.fr/event/3023/contributions/1764/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1764/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Conditioned limit theorems for products of positive random matrice
s
DTSTART:20180710T070000Z
DTEND:20180710T073000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1760@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Da Cam PHAM (Institut Denis Poisson\, Faculté d
es sciences\, Tours\, France.)\n\nInspired by a recent paper of I. Grama
\, E. Le Page and M. Peigné\, we consider a\nsequence $(g_n)_{n \\geq 1}$
of i.i.d. random $d \\times d -$ matrices with non negative entries and
study the fluctuations of the process $(\\log | g_n ... g_1 x ) {n \\geq 1
}$ for any non-zero vector $x$ in $R^d$ with non-negative coordinates. \nO
ur method involves approximating this process by a martingale and \nstud
ying harmonic functions for its restriction to the upper half line.\nUnde
r certain conditions\, the probability for this process to stay\nin the up
per half real line up to time $n$ decreases as \n$c \\over \\sqrt n$ for s
ome positive constant $c$.\n\nhttps://indico.math.cnrs.fr/event/3023/contr
ibutions/1760/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1760/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Proximal-type algorithm for structured nonsmooth nonconvex problem
involving linear operator
DTSTART:20180711T050000Z
DTEND:20180711T053000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1761@indico.math.cnrs.fr
DESCRIPTION:Speakers: Dang Khoa NGUYEN (Faculty of Mathematics\, Universit
y of Vienna\, Oskar-Morgenstern-Platz 1\, 1090 Vienna\, Austria)\n\nProxim
al operator\, since introduced by French mathematician Jean-Jacques Moreau
in 1962 [Moreau]\, became a fundamental object used to design algorithms
for nonsmooth optimization. \nWith reference [Attouch-Bolte] as a starting
point\, proximal-type algorithm for nonconvex model attracts huge interes
t due to its increasing applications in real world. However\, until recent
ly such model cannot contain complexly structure such as the composition o
f nonsmooth function with linear operator [Bolte-Sabach-Teboulle]\, otherw
ise\, we have to sacrifice the proximity step [Li-Pong].\n\nWe propose a p
roximal algorithm for minimizing a nonsmooth nonconvex complexly structure
d. Our algorithm relies on the augmented Lagrange [Gabay-Meicer] and is fo
rmulated in a full splitting spirit in the sense of Lions and Mercier \\ci
te{Lions-Mercier}: the nonsmooth functions are processed via their proxima
l operators\, the smooth function via gradient steps\, and the linear oper
ator via matrix times vector multiplication. In the setting of the Kurdyka
-Lojasiewicz property [Kurdyka]\, [Lojasiewicz]\, we show global convergen
ce and derive convergence rates for the iterates regarding the Lojasiewicz
exponent.\nFinally\, we show that the general difference of convex progra
mming can be written in our model. As a theoretical by-product\, we deduce
a scheme for this problem.\nThis talk relies on the joint works with Radu
Ioan Bot and Erno Robert Csetnek. \n\n\n[Attouch-Bolte] H. Attouch\, J. B
olte\, On the convergence of the proximal algorithm for nonsmooth function
s involving analytic features. Mathematical Programming 116(1)\, 5--16 (
2009).\n \n[Bolte-Sabach-Teboulle] J. Bolte\, S. Sabach and M. Teboulle
. Proximal alternating linearized minimization for nonconvex and nonsmooth
problems. Mathematical Programming\, 146(1)\, 459--494 (2014).\n \n[
Bot-Csetnek-Nguyen] R. I. Bot\, E. R. Csetnek and D.-K. Nguyen. A proximal
minimization algorithm for structured nonconvex and nonsmooth problems.\n
\n[Bot-Nguyen] R. I. Bot and D.-K. Nguyen. The proximal alternating di
rection method of multipliers in the nonconvex setting: convergence analys
is and rates.\n\n[Gabay-Meicer] D. Gabay and B. Mercier. A dual algorithm
for the solution of nonlinear variational problems via finite element appr
oximation. Computers and Mathematics with Applications 2(1)\, 17--40
(1976).\n \n[Kurdyka] K. Kurdyka. On gradients of functions definable i
n o-minimal structures. Annales de l’Institut Fourier 48\, 769--783 (1
998).\n \n[Li-Pong] G. Li and T. K. Pong. Global convergence of splitti
ng methods for nonconvex composite optimization. SIAM Journal on Optimizat
ion 25(4)\, 2434--2460 (2015).\n\n[Lions-Mercier] P. L. Lions and B. Mer
cier. Splitting Algorithms for the Sum of Two Nonlinear Operators.\nSIAM J
ournal on Numerical Analysis\, 16(6)\, 964--979 (1979)\n \n[Lojasiewicz
] S. Lojasiewicz. Une proprété topologique des sous-ensembles analytique
s réels\, Les Équations aux Dérivées Partielles. Éditions du Centre N
ational de la Recherche Scientifique\, Paris\, 8--89 (1963).\n\n[Moreau] J
. Moreau. Fonctions convexes duales et points proximaux dans un espace hil
bertien. \nComptes Rendus de l’Académie des Sciences (Paris)\, Série A
255\, 2897--2899 (1962).\n\nhttps://indico.math.cnrs.fr/event/3023/cont
ributions/1761/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1761/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On relaxation Methods for Mathematical Programs with Complementari
ty Constraints
DTSTART:20180709T030000Z
DTEND:20180709T040000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1752@indico.math.cnrs.fr
DESCRIPTION:Speakers: Mounir HADDOU (Centre de mathématiques Institut Nat
ional des Sciences Appliquées de Rennes\, France.)\n\nWe propose a new fa
mily of relaxation schemes for mathematical programs with complementarity\
nconstraints that extends the relaxations converging to an M-stationary p
oint.\nWe discuss the properties of the sequence of relaxed non-linear pro
grams as well as stationarity\nproperties of limiting points. We prove und
er a new and weak constraint qualification\, that\nour relaxation schemes
have the desired property of converging to an M-stationary point.\nUnfortu
nately\, in practice\, relaxed problems are only solved up to approximate
stationary\npoints and the guarantee of convergence to an M-stationary poi
nt is lost. \nWe define a new strong approximate stationarity condition an
d prove that we can maintain\nour guarantee of convergence and attain the
desired goal of computing an M-stationary point.\nA comprehensive numerica
l comparison between existing relaxations methods is performed\nand shows
promising results for our new methods.\nWe also propose di↵erent extensi
ons to tackle MPVC ( vanishing constraints) and MOCC\n(cardinality constra
ints) problems.\n\nhttps://indico.math.cnrs.fr/event/3023/contributions/17
52/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1752/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Numerical solution of a class of delay differential-algebraic equa
tions by half-explicit methods
DTSTART:20180709T040000Z
DTEND:20180709T050000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1758@indico.math.cnrs.fr
DESCRIPTION:Speakers: Hoang Linh VU (Faculty of Mathematics - Mechanics an
d Informatics\, Vietnam National University\, Hanoi\, Vietnam.)\n\nDelay d
ifferential-algebraic equations (DAEs) can be used for modeling real-life
phenomena that involve simultaneously time-delay effect and constraints. I
t is also known that solving delay DAEs is more complicated than solving n
on-delay ones because interpolation errors for the solution in the past ti
me may arise in addition to discretisation errors. Recently\, we have inve
stigated the efficient use of half-explicit methods for strangeness-free D
AEs (without delay). In this talk\, we propose and analyse some efficient
half-explicit methods for a class of structured strangeness-free DAEs with
constant delay. Convergence results for half-explicit linear multistep (H
ELM) methods and half-explicit Runge-Kutta (HERK) methods are obtained. Nu
merical experiments are also given for illustration.\n\nhttps://indico.mat
h.cnrs.fr/event/3023/contributions/1758/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1758/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Optimized Schwarz Waveform Relaxation and Applications to Semiline
ar Equations
DTSTART:20180710T040000Z
DTEND:20180710T050000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-3173@indico.math.cnrs.fr
DESCRIPTION:Speakers: Laurence Halpern\n\nhttps://indico.math.cnrs.fr/even
t/3023/contributions/3173/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/3173/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Multi-criteria Traffic Network Equilibrium Problem with Capacity C
onstraints
DTSTART:20180709T070000Z
DTEND:20180709T073000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1743@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Thanh Phuong TRUONG (Qui Nhon University)\n\nThi
s talk is aimed to present a single-product multi-criteria traffic network
with capacity constraints. We construct an optimization problem\, whose o
ptimal solutions are exactly equilibria of the model. Since the objective
function of this problem is neither continuous nor convex\, we propose a m
ethod to smoothen it and use optimization tools to find optimal solutions
of smooth optimization problems. Then\, we establish conditions\, under w
hich every equilibrium flow can be reached by these optimal solutions via
a limiting process. And we also develop a method based on a modified Frank
-Wolfe's gradient algorithm in order to obtain a subset of vector equilibr
ium flows\, which are located within a given distance from the chosen grid
of initial feasible flows. Numerical examples are reported to illustrate
our algorithms and their applicability.\n\nhttps://indico.math.cnrs.fr/eve
nt/3023/contributions/1743/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1743/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robust controllers for parabolic systems using the Galerkin approx
imation
DTSTART:20180709T074500Z
DTEND:20180709T081500Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1762@indico.math.cnrs.fr
DESCRIPTION:Speakers: Duc Duy PHAN (Tampere University of Technology)\n\nT
his is a joint work with Lassi Paunonen and Petteri Laakkonen\, Tampere Un
iversity of Technology.\n\nWe consider the robust output tracking problem
on state space $H$\n$$ \\dot{x} (t) = A x(t) + B u(t)\,$$\n$$ y(t) = C x(
t) + D u(t)\,$$\nwhere $x$ is the state\, $u$ is the input (control)\, and
$y$ is the output (observation). Our goal is to design a dynamic feedback
controller of the form \n$$\\dot{z}(t) = \\mathcal{G}_1 z(t) + \\mathcal{
G}_2 e(t)\,$$\n$$u(t) = K z(t)\,$$\n\nwhere $e(t) = y(t)- y_{ref}(t)$ is t
he regulation error in such a way that the output $y(t)$ of the system con
verges asymptotically to a given reference signal $y_{ref}(t)$. We propose
a new way of designing finite-dimensional robust controllers based on Gal
erkin approximations of infinite-dimensional controllers presented before
in [Pau16]. For a class of sesquilinear form $A$ and assumptions of approx
imation schemes proposed in [BI88\,BI97\,Mor94]\, we prove that the finite
dimensional controllers solve the Robust Output Regulation Problem. \\\\\
n\n[BI88] H. T. Banks and K. Ito.\nA unified framework for approximation i
n inverse problems for distributed parameter systems.\nControl Theory Adv.
Tech.\, 1988.\n \n[BI97] H. T. Banks and K. Ito. Approximation in LQR
Problems for Infinite Dimensional Systems With Unbounded Input Operators.\
nJ. Math. Systems Estim. Control\, 1997. \n \n[Mor94] K. A. Morris.
Design of finite-dimensional controllers for infinite-dimensional systems
by approximation.\nJ. Math. Systems Estim. Control\, 4(2):30\, 1994.\n
\n[Pau16] L. Paunonen. Controller Design for Robust Output Regulation of R
egular Linear Systems.\nIEEE Transactions on Automatic Control}\, 61(10):2
974--2986\, Oct 2016.\n\nhttps://indico.math.cnrs.fr/event/3023/contrib
utions/1762/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1762/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Limit theorems for random walks in random environment
DTSTART:20180709T084500Z
DTEND:20180709T091500Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1765@indico.math.cnrs.fr
DESCRIPTION:Speakers: Hoang Chuong LAM (Can Tho University)\n\nWe prove th
e quenched central limit theorem and the law of large numbers for reversib
le random walks in a stationary random environment on $Z$. In this model\,
the conductivity of the edge between $[k\; k+1]$ is equal to $\\alpha_{k}
c(T^{k}\\omega)$\, where $\\alpha_{k}$ be a positive number and $c$ be a
positive measurable function on $\\Omega.$\nFix $\\omega \\in \\Omega\,$
we consider the Poisson equation $(P_{\\omega}-I)f=\\psi$\, and then use t
he pointwise ergodic theorem to treat the limit of solutions and then the
limit theorems will be established by the convergence of moments.\n\nDepau
w\, J and Derrien\, J.-M. (2009). Variance limite d'une marche aléatoire
réversible en milieu aléatoire sur ${Z}$. C. R. Acad. Sci. Paris\, Ser.
I. 347 p.401-406.\n\nLam\, H.-C. (2014). Quenched central limit theorem
for reversible random waks in random environment on \n${Z}$. Journal of Ap
plied Probability. 51 1-14.\n\nhttps://indico.math.cnrs.fr/event/3023/cont
ributions/1765/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1765/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On sensitivity analysis in set-valued optimization via second-orde
r composed contingent derivatives
DTSTART:20180709T093000Z
DTEND:20180709T100000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1742@indico.math.cnrs.fr
DESCRIPTION:Speakers: Le Hoang Anh Nguyen (University of science\, VNU-HCM
US)\n\nIn the talk\, we discuss calculus rules of second-order composed co
ntingent\nderivatives for set-valued maps. More precisely\, chain rule and
sum rule are established\, and\ntheir applications to some particular mat
hematical models are obtained. Then\, sensitivity\nanalysis in set-valued
optimization using second-order composed contingent derivatives are\npropo
sed.\n\nhttps://indico.math.cnrs.fr/event/3023/contributions/1742/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1742/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Is early fungicidal activity a surrogate marker for mortality in t
he evaluation of antifungal therapies in HIV-associated cryptococcal menin
gitis ?
DTSTART:20180709T093000Z
DTEND:20180709T100000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1741@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thanh Hoang Nhat LE (Oxford University Clinical Rese
arch Unit\, Wellcome Trust Major Overseas Programme\, Vietnam)\n\n*Backgro
und*: Early fungicidal activity (EFA)\, i.e. the CSF clearance rate of qua
ntitative yeast culture colony counts during the first 14 days of antifung
al therapy\, is often used as the primary endpoint in phase II trials in H
IV-associated cryptococcal meningitis. While associations between EFA and
survival have been reported\, it is unclear whether EFA is a surrogate mar
ker. \n\n*Methods*: Data from eight randomized controlled trials and four
cohort studies from Asia and Africa (23 distinct treatment and study combi
nations) were pooled. EFA was estimated based on a linear mixed effects mo
del of the longitudinal log10-CSF Cryptococcus colony forming unit (CFU) c
ounts treating values below the detection limit as left-censored. Ten-week
risks of death were estimated with the Kaplan-Meier method. \n\n*Results*
: Data from 976 subjects contributing a total of 2851 quantitative culture
measurements were included. Median EFA and 10-week risks of death were ¬
0.13 log10 CFU/ml/day and 55% for fluconazole monotherapy (n=80)\, 0.27
and 43% for fluconazole/flucytosine combinations (n=21)\, 0.35 and 38% f
or amphotericin B monotherapy (n=152)\, 0.35 and 36% for amphotericin B/a
zole combinations (n=441)\, 0.49 and 26% for amphotericin B/flucytosine c
ombinations (n=224)\, and 0.58 and 30% for amphotericin B/flucytosine/int
erferon-gamma combinations (n=58). There was a positive correlation betwee
n faster EFA and 10-week mortality across treatment/study combinations (R2
=0.44\, 95%CI: 0.14-0.71). However\, correlation between observed treatmen
t effects on EFA and 10-week mortality from randomized clinical trials (R2
trial=0.04\, 95%CI: 0.00-0.47\; n=620)\, and average correlations between
an individuals’ EFA and survival time within treatment/study combination
s (average squared Somers’ rank correlation R2indiv=0.07\, 95%CI: 0.04-0
.11) were low.\n\n*Conclusion*: EFA remains a useful marker of antifungal
activity but surrogacy for 10-week mortality could not be established. Lim
itations of this study are that azole and azole combination treatments wer
e more often used in the most resource-limited settings\, and that only on
e of the included antifungal trials was powered for mortality.\n\nhttps://
indico.math.cnrs.fr/event/3023/contributions/1741/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1741/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Asymptotic behavior of the error between two different Euler schem
es for the Lévy driven SDEs
DTSTART:20180711T050000Z
DTEND:20180711T053000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1748@indico.math.cnrs.fr
DESCRIPTION:Speakers: Ahmed KEBAIER (Associate Professor)\, Mohamed BEN AL
AYA (Professor)\, Thi Bao Tram NGO (PhD student)\n\nWe study the Multi-lev
el Monte Carlo method introduced by Giles [3] and its applications to fina
nce which is significantly more efficient than the classical Monte Carlo m
ethod. This method for the stochastic differential equations driven by onl
y Brownian Motion had been studied by Ben Alaya and Kebaier [2]. Here\, we
consider the stochastic differential equation driven by a pure jump Lévy
process. When the Lévy process have a Brownian component\, the speed of
convergence of the multilevel was recently studied by Dereich and Li [4].
\n \nNow\, we prove the stable law convergence theorem in the spirit of
Jacod [1]. More precisely\, we consider the SDE of form \n\\begin{equat
ion} \nX_t=x_0+\\int_0^t f(X_{s-})dY_s\, (1) \n\\end{equation} \nwit
h $f\\in\\mathcal{C}^3$ and $Y$ is a Lévy process with the triplet $(b\,0
\,F)$ and look at the asymptotic behavior of the normalized error process
$u_{n\,m}(X^n-X^{nm})$ where $X^n$ and $X^{nm}$ are two different Euler ap
proximations with step sizes $1/n$ and $1/nm$ respectively. The rate $u_{n
\,m}$ is an appropriate rate going to infinity such that the normalized er
ror converges to non-trivial limit. Under some different assumptions on th
e properties of the Lévy process $Y$ in $(1)$\, we found different suitab
le forms of the rate $u_{n\,m}$. \n \n[1] Jean Jacod. The Euler scheme
for Lévy driven stochastic differential equations: Limit theorems. The An
nals of Probability\, 2004\, Vol.32\, No.3A\, 1830-1872. \n \n[2] Moham
ed Ben Alaya and Ahmed Kebaier. Central limit theorem for the multilevel M
onte Carlo Euler method. Ann.Appl. Probab. 25(1): 211-234\, 2015. \n \n
[3] Michael B.Giles. Multilevel Monte Carlo path simulation\, Oper. Res.\,
56(3): 607-617\, 2008. \n \n[4] Steffen Dereich and Sangmeng Li. Multi
level Monte Carlo for Lévy-driven SDEs: Central limit theorems for adapti
ve Euler schemes. Ann. Appl. Probab.\, 26(1): 136-185\, 2016.\n\nhttps://i
ndico.math.cnrs.fr/event/3023/contributions/1748/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1748/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Optimized wavelet-Gaussian mixed bases for electronic structure ca
lculations in quantum chemistry
DTSTART:20180710T030000Z
DTEND:20180710T040000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1755@indico.math.cnrs.fr
DESCRIPTION:Speakers: Quang Huy TRAN (IFPEN)\n\nMany applications of quant
um chemistry involve ab initio simulations. These are feasible thanks to w
ell-known approximations to the Schrödinger equation\, such as Hartree-Fo
ck’s or Density Functional Theory. More than 70 softwares are available
to chemists in this field\, the most common ones being VASP\, Gaussian and
ABINIT. A key difference between them lies in the basis functions selecte
d to express the molecular orbitals. One of the newcomers\, the massively
parallel program BigDFT\, uses wavelet bases for performance consideration
s.\n \nTo better capture the cusp singularities of the orbitals in the all
-electron calculations without increasing the complexity of BigDFT\, we su
ggest enriching the wavelet basis by Gaussian functions centered at each n
ucleus position. To optimize the construction of additional Gaussian funct
ions\, we rely on a combination of a posteriori error estimates and the gr
eedy algorithm. We adapt the ideas from Maday and his co-authors to establ
ish that the dual norm of the residue can serve as an effective estimate f
or the energy decrease between the pure-wavelet solution and the augmented
-basis solution. Furthermore\, in a similar spirit with reduced-basis tech
niques\, we recommend the greedy algorithm for building an incremental seq
uence of additional Gaussian functions.\n \nAs a proof of concept to this
strategy\, we investigate a one-dimensional model of Schrödinger type wit
h delta potentials\, which represents a system of one electron and several
nuclei of known charges and positions. Due to the small number of additio
nal degrees of freedom\, wavelet-Gaussian mixed bases exhibit a significan
t gain in accuracy while having a low computational cost. This testifies t
o the interest of this approach.\n\nhttps://indico.math.cnrs.fr/event/3023
/contributions/1755/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1755/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The numerical high cycle fatigue damage model of fillet weld joint
under weld-induced residual stresses
DTSTART:20180710T074500Z
DTEND:20180710T081500Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1744@indico.math.cnrs.fr
DESCRIPTION:Speakers: Nguyen Van Vuong DO (Ton Duc Thang University)\n\nIn
this study\, a development of nonlinear continuum damage mechanics (CDM)
model for multiaxial high cycle fatigue is proposed in which the cyclic pl
asticity constitutive model has been incorporated in the finite element (F
E) framework. T-joint FE simulation of fillet welding is implemented to ch
aracterize sequentially coupled three-dimensional (3-D) of thermo-mechanic
al FE formulation and simulate the welding residual stresses. The high cyc
le fatigue damage model is then taken account into the fillet weld joints
under the various cyclic fatigue load types to calculate the fatigue life
considering the residual stresses. The fatigue crack initiation and the pr
opagation in the present model estimated for the total fatigue is compared
with the experimental results. The FE results illustrated that the propos
ed high cycle fatigue damage model in this study could become a powerful t
ool to effectively predict the fatigue life of the welds. Parametric studi
es in this work are also demonstrated that the welding residual stresses c
annot be ignored in the computation of the fatigue life of welded structur
es.\n\nhttps://indico.math.cnrs.fr/event/3023/contributions/1744/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1744/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Coupled Parareal-Optimized Schwarz Waveform relaxation method for
advection reaction diffusion equation
DTSTART:20180711T041500Z
DTEND:20180711T044500Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1747@indico.math.cnrs.fr
DESCRIPTION:Speakers: Caroline japhet (University Paris 13)\, Pascal Omnes
(CEA Saclay and University Paris 13)\, Yvon Maday (UPMC)\, Duc Quang Bui
(University Paris 13)\n\nParareal method is a numerical method to solve ti
me - evolutional problems in parallel\, which uses two propagators: the co
arse - fast and inaccurate - and the fine - slow but more accurate. Instea
d of running the fine propagator on the whole time interval\, we divide th
e time space into small time intervals\, where we can run the fine propaga
tor in parallel to obtain the desired solution\, with the help of the coar
se propagator and through parareal steps. Furthermore\, each local subprob
lem can be solved by an iterative method\, and instead of doing this local
iterative method until convergence\, one may perform only a few iteration
s of it\, during parareal iterations. Propagators then become much cheaper
but sharply lose their accuracy\, and we hope that the convergence will b
e achieved across parareal iterations. \n \nIn this talk\, we propose t
o couple Parareal with a well-known iterative method - Optimized Schwarz W
aveform Relaxation (OSWR) - with only few OSWR iterations in the fine prop
agator and with a simple coarse propagator deduced from Backward Euler met
hod. We present the analysis of this coupled method for 1-dimensional adve
ction reaction diffusion equation\, for this case the convergence is almos
t linear. We also give some numerical illustrations for 1D and 2D equation
s\, which shows that the convergence is much faster in practice.\n\nhttps:
//indico.math.cnrs.fr/event/3023/contributions/1747/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1747/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dissipative hyperbolic systems and their diffusion large-time beha
viors: Linear cases
DTSTART:20180711T041500Z
DTEND:20180711T044500Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-1763@indico.math.cnrs.fr
DESCRIPTION:Speakers: Tien Thinh NGUYEN (Gran Sasso Science Institute\, It
aly)\n\nDissipative hyperbolic systems play a central role in many applica
tions including the kinetic models for gas dynamics and the relaxation num
erical schemes approximating conservation laws. One important feature of t
his kind of systems is the diffusion limit of solution as time tends to in
finity. In this talk\, we will discuss some reasonable dissipative structu
res such that for large time\, the unique solution to the initial value pr
oblem for\n\n$$\\partial_tu+\\sum_{j=1}^dA_j\\partial_{x_j}u+Bu=0$$\n\nis
approximated by a solution to the initial value problem for a parabolic sy
stem\, where $A_j$ and $B$ are $n\\times n$ matrices with real constant en
tries\, and $u=u(x\,t)$ is an $n$-dimensional real vector. The approximati
on is of order $\\mathcal O\\bigl(t^{-\\frac d2(\\frac 1q-\\frac 1p)-\\alp
ha}\\bigr)$ for $\\alpha\\in\\{1/2\,1\\}$ and $1\\le q\\le p\\le \\infty$\
, up to an exponentially decaying error. This optimal result in [masciangu
yen17\,nguyen18] is a generalization of [bianchini07] at the linear level.
The main idea is based on the perturbation theory for linear operators an
d the Fourier analysis.\n\nIn collaboration with Corrado Mascia (Universit
à di Roma 1 - Italy).\n\n[bianchini07] S. Bianchini\, B. Hanouzet and R.
Natalini\, Asymptotic behavior of smooth solutions for partially dissipati
ve hyperbolic systems with a convex entropy\, Comm. Pure Appl. Math.\, 60
(2007)\, 1559 -- 1622.\n\n[mascianguyen17] C. Mascia and T. T. Nguyen\, $L
^p$-$L^q$ decay estimates for dissipative linear hyperbolic systems in 1D\
, J. Differential Equations\, 263 (2017)\, 6189 -- 6230.\n\n[nguyen18] T.
T. Nguyen\, Asymptotic limit and decay estimates for a class of dissipativ
e linear hyperbolic systems in several dimensions\, Discrete Contin. Dyn.
Syst.\, (to appear).\n\nhttps://indico.math.cnrs.fr/event/3023/contributio
ns/1763/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/1763/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Reflections on waves and waves reflections
DTSTART:20180710T020000Z
DTEND:20180710T030000Z
DTSTAMP:20230922T144000Z
UID:indico-contribution-3159@indico.math.cnrs.fr
DESCRIPTION:Speakers: Fabrice PLANCHON\n\nWe will review recent results on
the propagation\nof waves on domains\, with emphasis on two extreme\ncase
s: the exterior or the interior of a stricly convex\ndomain. Understanding
the wave localization\, its\namplitude and how it decays is fundamental f
or\nseveral (unrelated) problems and we will describe an\ninteresting inte
rplay between geometrical aspects and\ndegenerate oscillatory integrals th
at model waves\n\nhttps://indico.math.cnrs.fr/event/3023/contributions/315
9/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/3159/
END:VEVENT
END:VCALENDAR