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BEGIN:VEVENT
SUMMARY:Fast Kinetic Monte Carlo Methods for Novel Solar Cell Design
DTSTART;VALUE=DATE-TIME:20180710T070000Z
DTEND;VALUE=DATE-TIME:20180710T073000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1740@indico.math.cnrs.fr
DESCRIPTION:Speakers: Tan Trung NGUYEN (Department of Mathematical Science
s Bath University)\nThis is a joint work with A. Walker\, R. Scheichl and
C.A. Yates\, Bath University\n\nKinetic Monte Carlo (KMC) methods [1] are
widely used to simulate the surface adsorption\, diffusion\,\ngrowth\, sta
tistical physics\, radiation damage annealing\, bioglogical systems\, amon
gst other applications\nby evolving systems dynamically from state to stat
e. In our application to solar cells\, KMC are required\nto predict device
behaviour from the material properties at the microscopic scale. Our work
has mainly\nfocussed on atomistic studies of the microscopic processes\,
such as charge and exciton hopping\, recombination rates and light absorpt
ion. Using the parameters obtained from the atomistic simulations\, we foc
us on KMC simulations at the mesoscale\, computing current-voltage charact
eristics\, charge mobilities and parameters for calculating recombination
that subsequently feed into faster device design offered by continuum mode
ls where current-voltage characteristics are obtained.\n\nThe KMC method i
s equivalent to the Gillespie algorithm [2] which simulates the trajectori
es consistent\nwith the “exact” dynamical evolution of a system. The a
dvantage 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 tha
t same trajectory in the molecular dynamics which is much more expensive s
ince one propagates equations of motion forward in time. However\, the com
putational cost is still very high in many practical applications such as
solar cell design\, bioglogical systems.\n\nIn order to accelerate atomist
ic simulations\, we apply the idea of multilevel Monte Carlo (MLMC)\nmetho
ds [3] to reduce the computational time significantly but still retain the
accuracy based on controlling statistical errors. The first results we ha
ve obtained with r-leaping and tau-leaping show the efficiency when skippi
ng expensive computations such as the update of the electrostatic potentia
l (the most expensive) and propensity functions in such a way that the sta
tistical errors are still acceptable (less than 10%).\nIn particular for s
olar cell designs\, this development will be coupled with fast and massive
ly parallel Poisson solvers for the modelling of long-range interactions.\
n\n[1] U. Neupane\, B. Bahrami\, M. Biesecker\, and Baroughi M.F. Kinetic
monte carlo modeling on organic\nsolar cells: Domain size\, donor-acceptor
ratio and thickness. Nano Energy\, 81:128–137\, 2017.\n\n[2] D.T. Gille
spi. 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 simulation
\nof stochastic biological systems. Bull Math Biol\, 2016\n\nhttps://indic
o.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;VALUE=DATE-TIME:20180710T083000Z
DTEND;VALUE=DATE-TIME:20180710T090000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1739@indico.math.cnrs.fr
DESCRIPTION:Speakers: Anh Ha LE (University of science\, VNU-HCMUS)\nIn th
is paper\, we will consider a posteriori error estimation for the transpor
t equation $\\partial_t u+\\mathbf{a}(x\,t)\\cdot\\nabla u=0$ with the ini
tial data $u_0\\in L^\\infty\\cap BV_{{\\rm loc}}$ and the divergence of t
he velocity field $\\mathbf{a}$ is not equal to zero. An a posteriori esti
mate for the error between the exact solution and the solution of an upwin
d finite volume scheme is derived in the $L^1$ norm.\n\nhttps://indico.mat
h.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;VALUE=DATE-TIME:20180710T074500Z
DTEND;VALUE=DATE-TIME:20180710T081500Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1746@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Nguyet Nga TA (University of science\, VNU-HCMUS
)\nWe study stationary equation governed by the operator $ -\\nabla \\cdot
A(x\, \\nabla u) =\n\\mu$ in the case where $A(x\, \\xi)$ is a maximal m
onotone graph and $\\mu$ is a Radon measure. Our main interest concerns th
e typical situation where $A(x\, .)$ is defined only in a bounded region o
f $\\mathbf{R}^n$\; so that $A(x\, .)$ does not satisfies the standard pol
ynomial growth control condition. The natural energy space in this case is
the space of Lipschitz continuous function and the flux is a vector value
d measure. We using tangential gradient with respect to a Radon measure to
pass through this difficulty.\n\nhttps://indico.math.cnrs.fr/event/3023/c
ontributions/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;VALUE=DATE-TIME:20180710T083000Z
DTEND;VALUE=DATE-TIME:20180710T090000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1745@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thanh Binh NGUYEN (University of science\, VNU-HCMUS
)\nIn this work\, we introduce a novel method for solving the set inversio
n problem by formulating it as a binary classification problem. Aiming to
develop a fast algorithm that can work effectively with high-dimensional a
nd computation- ally expensive nonlinear models\, we focus on active learn
ing\, a family of new and powerful techniques which can achieve the same l
evel of accuracy with fewer data points compared to traditional learning m
ethods. Specifically\, we propose OASIS\, an active learning framework usi
ng Support Vector Machine algorithms for solving the problem of set invers
ion. Our method works well in high dimensions and its computational cost i
s relatively robust to the increase of dimension. We illustrate the perfor
mance of OASIS by several simulation studies and show that our algorithm o
utperforms VISIA\, the state-of-the-art method.\n\nhttps://indico.math.cnr
s.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;VALUE=DATE-TIME:20180711T020000Z
DTEND;VALUE=DATE-TIME:20180711T030000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1749@indico.math.cnrs.fr
DESCRIPTION:Speakers: Richard EMILION (Mathématiques – Analysie\, Proba
bilités\, Modélisation\, Université d’Orléans\, France.)\nOur contex
t is the statistic of a random distribution\, that is a random variable ta
king values in a space of probability measures. Such a context is useful w
hen dealing with classes of raw data of a large dataset or with objects ha
ving a complex behaviour. \nWe present the theoretical framework\, some e
xamples of models\, the likelihood for finite dimensional estimators and s
ome recent applications.\n\nhttps://indico.math.cnrs.fr/event/3023/contrib
utions/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;VALUE=DATE-TIME:20180709T020000Z
DTEND;VALUE=DATE-TIME:20180709T030000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1753@indico.math.cnrs.fr
DESCRIPTION:Speakers: Marc PEIGNE (Laboratoire de Mathématiques et Physiq
ue Théorique\, Faculté des Sciences et Techniques Université François
Rabelais\, France.)\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;VALUE=DATE-TIME:20180709T074500Z
DTEND;VALUE=DATE-TIME:20180709T081500Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1757@indico.math.cnrs.fr
DESCRIPTION:Speakers: Van Luyen LE (University of science\, VNU-HCMUS)
\nMultivariate public key cryptography (MPKC) is one of the main candidate
s for post-quantum cryptography. Rainbow\, an improved\n(multi-layer) vers
ion of Unbalanced Oil and Vinegar (UOV)\, is one of the most famous multiv
ariate signature scheme that is a promising candidate for NIST standardiza
tion. At INDOCRYPT 2017\, Beullens and Preneel introduced a new variant LU
OV 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 dramati
cally reduces the public key size.\n \nIn this talk\, we extend that id
ea to Rainbow and theoretically yield the optimal choice for the subfield
$L$ over which a Rainbow is generated before being lifted to $K$. As a res
ult\, we can deduce the public key size to $37.5 \\%$.\n\nhttps://indico.m
ath.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;VALUE=DATE-TIME:20180711T030000Z
DTEND;VALUE=DATE-TIME:20180711T040000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1751@indico.math.cnrs.fr
DESCRIPTION:Speakers: Felix KWOK (Department of Mathematics\, Hong Kong Ba
ptist University\, Hong Kong felix_kwok@hkbu.edu.hk)\nOne way to accelerat
e the numerical solution of a nonlinear elliptic problem is to use nonline
ar preconditioning\, which replaces the original discretized problem by an
equivalent but easier one. In this talk\, we discuss how a fixed point it
eration for a nonlinear system can be used in combination of Newton's meth
od to yield highly efficient\, nonlinearly preconditioned methods. Our sta
rting point is the Restricted Additive Schwarz Preconditioned Exact Newton
(RASPEN) method by Dolean et al.~(2016)\, which is derived from the nonli
near Restricted Additive Schwarz method. We then show how to extend this m
ethod to include a coarse component\, as well as how to incorporate optimi
zed transmission conditions of the Robin type. Finally\, we will show some
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;VALUE=DATE-TIME:20180709T070000Z
DTEND;VALUE=DATE-TIME:20180709T073000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1759@indico.math.cnrs.fr
DESCRIPTION:Speakers: Tien Dat CAO (Texas Tech University)\nWe study the l
arge time behavior of solutions to the three-dimensional Navier-Stokes equ
ations with periodic boundary conditions. It is shown that if the force ha
s an asymptotic expansion\, as time tends to infinity\, with respect to ce
rtain families of decaying functions in Sobolev-Gevrey space\, then any we
ak solution admits an asymptotic expansion of the same type. In particular
\, we establish the expansions in terms of power decaying functions and th
e $\\log$ or $\\log(\\log)$ decaying ones. This is a joint work with Luan
Hoang (Texas Tech University).\n\nhttps://indico.math.cnrs.fr/event/3023/c
ontributions/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;VALUE=DATE-TIME:20180709T084500Z
DTEND;VALUE=DATE-TIME:20180709T091500Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1764@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Thu Van NGUYEN (University of science\, VNU-HCMU
S)\nIn this talk a quasi-equilibrium problem with a nonmonotone bifunction
is considered in a finite dimensional space. This is a kind of equilibriu
m problem in sense of Blum and Oettli\, or also called Ky Fan inequality\,
with a constraint set depending on the current point. An extragradient-ty
pe method is presented and analyzed for its solution. The convergence of t
he method is proved under the assumption that the solution set of an assoc
iated dual equilibrium problem is nonempty.\n\nhttps://indico.math.cnrs.f
r/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;VALUE=DATE-TIME:20180710T070000Z
DTEND;VALUE=DATE-TIME:20180710T073000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1760@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Da Cam PHAM (Institut Denis Poisson\, Faculté d
es sciences\, Tours\, France.)\nInspired by a recent paper of I. Grama\,
E. Le Page and M. Peigné\, we consider a\nsequence $(g_n)_{n \\geq 1}$ o
f i.i.d. random $d \\times d -$ matrices with non negative entries and st
udy 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. \nOur
method involves approximating this process by a martingale and \nstudyi
ng harmonic functions for its restriction to the upper half line.\nUnder
certain conditions\, the probability for this process to stay\nin the uppe
r half real line up to time $n$ decreases as \n$c \\over \\sqrt n$ for som
e positive constant $c$.\n\nhttps://indico.math.cnrs.fr/event/3023/contrib
utions/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;VALUE=DATE-TIME:20180711T050000Z
DTEND;VALUE=DATE-TIME:20180711T053000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1761@indico.math.cnrs.fr
DESCRIPTION:Speakers: Dang Khoa NGUYEN (Faculty of Mathematics\, Universit
y of Vienna\, Oskar-Morgenstern-Platz 1\, 1090 Vienna\, Austria)\nProximal
operator\, since introduced by French mathematician Jean-Jacques Moreau i
n 1962 [Moreau]\, became a fundamental object used to design algorithms fo
r nonsmooth optimization. \nWith reference [Attouch-Bolte] as a starting p
oint\, proximal-type algorithm for nonconvex model attracts huge interest
due to its increasing applications in real world. However\, until recently
such model cannot contain complexly structure such as the composition of
nonsmooth function with linear operator [Bolte-Sabach-Teboulle]\, otherwis
e\, we have to sacrifice the proximity step [Li-Pong].\n\nWe propose a pro
ximal algorithm for minimizing a nonsmooth nonconvex complexly structured.
Our algorithm relies on the augmented Lagrange [Gabay-Meicer] and is form
ulated in a full splitting spirit in the sense of Lions and Mercier \\cite
{Lions-Mercier}: the nonsmooth functions are processed via their proximal
operators\, the smooth function via gradient steps\, and the linear operat
or via matrix times vector multiplication. In the setting of the Kurdyka-L
ojasiewicz property [Kurdyka]\, [Lojasiewicz]\, we show global convergence
and derive convergence rates for the iterates regarding the Lojasiewicz e
xponent.\nFinally\, we show that the general difference of convex programm
ing 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 I
oan Bot and Erno Robert Csetnek. \n\n\n[Attouch-Bolte] H. Attouch\, J. Bol
te\, On the convergence of the proximal algorithm for nonsmooth functions
involving analytic features. Mathematical Programming 116(1)\, 5--16 (20
09).\n \n[Bolte-Sabach-Teboulle] J. Bolte\, S. Sabach and M. Teboulle.
Proximal alternating linearized minimization for nonconvex and nonsmooth p
roblems. Mathematical Programming\, 146(1)\, 459--494 (2014).\n \n[Bo
t-Csetnek-Nguyen] R. I. Bot\, E. R. Csetnek and D.-K. Nguyen. A proximal m
inimization algorithm for structured nonconvex and nonsmooth problems.\n
\n[Bot-Nguyen] R. I. Bot and D.-K. Nguyen. The proximal alternating dire
ction method of multipliers in the nonconvex setting: convergence analysis
and rates.\n\n[Gabay-Meicer] D. Gabay and B. Mercier. A dual algorithm fo
r the solution of nonlinear variational problems via finite element approx
imation. Computers and Mathematics with Applications 2(1)\, 17--40 (1
976).\n \n[Kurdyka] K. Kurdyka. On gradients of functions definable in
o-minimal structures. Annales de l’Institut Fourier 48\, 769--783 (199
8).\n \n[Li-Pong] G. Li and T. K. Pong. Global convergence of splitting
methods for nonconvex composite optimization. SIAM Journal on Optimizatio
n 25(4)\, 2434--2460 (2015).\n\n[Lions-Mercier] P. L. Lions and B. Merci
er. Splitting Algorithms for the Sum of Two Nonlinear Operators.\nSIAM Jou
rnal on Numerical Analysis\, 16(6)\, 964--979 (1979)\n \n[Lojasiewicz]
S. Lojasiewicz. Une proprété topologique des sous-ensembles analytiques
réels\, Les Équations aux Dérivées Partielles. Éditions du Centre Nat
ional de la Recherche Scientifique\, Paris\, 8--89 (1963).\n\n[Moreau] J.
Moreau. Fonctions convexes duales et points proximaux dans un espace hilbe
rtien. \nComptes Rendus de l’Académie des Sciences (Paris)\, Série A
255\, 2897--2899 (1962).\n\nhttps://indico.math.cnrs.fr/event/3023/contri
butions/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;VALUE=DATE-TIME:20180709T030000Z
DTEND;VALUE=DATE-TIME:20180709T040000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1752@indico.math.cnrs.fr
DESCRIPTION:Speakers: Mounir HADDOU (Centre de mathématiques Institut Nat
ional des Sciences Appliquées de Rennes\, France.)\nWe propose a new fami
ly of relaxation schemes for mathematical programs with complementarity\nc
onstraints that extends the relaxations converging to an M-stationary poi
nt.\nWe discuss the properties of the sequence of relaxed non-linear progr
ams as well as stationarity\nproperties of limiting points. We prove under
a new and weak constraint qualification\, that\nour relaxation schemes ha
ve the desired property of converging to an M-stationary point.\nUnfortuna
tely\, in practice\, relaxed problems are only solved up to approximate st
ationary\npoints and the guarantee of convergence to an M-stationary point
is lost. \nWe define a new strong approximate stationarity condition and
prove that we can maintain\nour guarantee of convergence and attain the de
sired goal of computing an M-stationary point.\nA comprehensive numerical
comparison between existing relaxations methods is performed\nand shows pr
omising results for our new methods.\nWe also propose di↵erent extension
s to tackle MPVC ( vanishing constraints) and MOCC\n(cardinality constrain
ts) problems.\n\nhttps://indico.math.cnrs.fr/event/3023/contributions/1752
/
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;VALUE=DATE-TIME:20180709T040000Z
DTEND;VALUE=DATE-TIME:20180709T050000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1758@indico.math.cnrs.fr
DESCRIPTION:Speakers: Hoang Linh VU (Faculty of Mathematics - Mechanics an
d Informatics\, Vietnam National University\, Hanoi\, Vietnam.)\nDelay dif
ferential-algebraic equations (DAEs) can be used for modeling real-life ph
enomena that involve simultaneously time-delay effect and constraints. It
is also known that solving delay DAEs is more complicated than solving non
-delay ones because interpolation errors for the solution in the past time
may arise in addition to discretisation errors. Recently\, we have invest
igated the efficient use of half-explicit methods for strangeness-free DAE
s (without delay). In this talk\, we propose and analyse some efficient ha
lf-explicit methods for a class of structured strangeness-free DAEs with c
onstant delay. Convergence results for half-explicit linear multistep (HEL
M) methods and half-explicit Runge-Kutta (HERK) methods are obtained. Nume
rical experiments are also given for illustration.\n\nhttps://indico.math.
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;VALUE=DATE-TIME:20180710T040000Z
DTEND;VALUE=DATE-TIME:20180710T050000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-3173@indico.math.cnrs.fr
DESCRIPTION:Speakers: Laurence Halpern ()\nhttps://indico.math.cnrs.fr/eve
nt/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;VALUE=DATE-TIME:20180709T070000Z
DTEND;VALUE=DATE-TIME:20180709T073000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1743@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Thanh Phuong TRUONG (Qui Nhon University)\nThis
talk is aimed to present a single-product multi-criteria traffic network w
ith capacity constraints. We construct an optimization problem\, whose opt
imal solutions are exactly equilibria of the model. Since the objective fu
nction of this problem is neither continuous nor convex\, we propose a met
hod to smoothen it and use optimization tools to find optimal solutions of
smooth optimization problems. Then\, we establish conditions\, under whi
ch 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-W
olfe's gradient algorithm in order to obtain a subset of vector equilibriu
m flows\, which are located within a given distance from the chosen grid o
f initial feasible flows. Numerical examples are reported to illustrate ou
r algorithms and their applicability.\n\nhttps://indico.math.cnrs.fr/event
/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;VALUE=DATE-TIME:20180709T074500Z
DTEND;VALUE=DATE-TIME:20180709T081500Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1762@indico.math.cnrs.fr
DESCRIPTION:Speakers: Duc Duy PHAN (Tampere University of Technology)\nThi
s is a joint work with Lassi Paunonen and Petteri Laakkonen\, Tampere Univ
ersity 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 c
ontroller 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 the
regulation error in such a way that the output $y(t)$ of the system conve
rges asymptotically to a given reference signal $y_{ref}(t)$. We propose a
new way of designing finite-dimensional robust controllers based on Galer
kin approximations of infinite-dimensional controllers presented before in
[Pau16]. For a class of sesquilinear form $A$ and assumptions of approxim
ation schemes proposed in [BI88\,BI97\,Mor94]\, we prove that the finite d
imensional controllers solve the Robust Output Regulation Problem. \\\\\n\
n[BI88] H. T. Banks and K. Ito.\nA unified framework for approximation in
inverse problems for distributed parameter systems.\nControl Theory Adv. T
ech.\, 1988.\n \n[BI97] H. T. Banks and K. Ito. Approximation in LQR Pr
oblems for Infinite Dimensional Systems With Unbounded Input Operators.\nJ
. Math. Systems Estim. Control\, 1997. \n \n[Mor94] K. A. Morris. De
sign 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 Reg
ular Linear Systems.\nIEEE Transactions on Automatic Control}\, 61(10):297
4--2986\, Oct 2016.\n\nhttps://indico.math.cnrs.fr/event/3023/contribut
ions/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;VALUE=DATE-TIME:20180709T084500Z
DTEND;VALUE=DATE-TIME:20180709T091500Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1765@indico.math.cnrs.fr
DESCRIPTION:Speakers: Hoang Chuong LAM (Can Tho University)\nWe prove the
quenched central limit theorem and the law of large numbers for reversible
random walks in a stationary random environment on $Z$. In this model\, t
he 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 po
sitive measurable function on $\\Omega.$\nFix $\\omega \\in \\Omega\,$ we
consider the Poisson equation $(P_{\\omega}-I)f=\\psi$\, and then use the
pointwise ergodic theorem to treat the limit of solutions and then the li
mit theorems will be established by the convergence of moments.\n\nDepauw\
, J and Derrien\, J.-M. (2009). Variance limite d'une marche aléatoire r
éversible 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 fo
r reversible random waks in random environment on \n${Z}$. Journal of Appl
ied Probability. 51 1-14.\n\nhttps://indico.math.cnrs.fr/event/3023/contri
butions/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;VALUE=DATE-TIME:20180709T093000Z
DTEND;VALUE=DATE-TIME:20180709T100000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1742@indico.math.cnrs.fr
DESCRIPTION:Speakers: Le Hoang Anh Nguyen (University of science\, VNU-HCM
US)\nIn the talk\, we discuss calculus rules of second-order composed cont
ingent\nderivatives for set-valued maps. More precisely\, chain rule and s
um rule are established\, and\ntheir applications to some particular mathe
matical models are obtained. Then\, sensitivity\nanalysis in set-valued op
timization using second-order composed contingent derivatives are\npropose
d.\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;VALUE=DATE-TIME:20180709T093000Z
DTEND;VALUE=DATE-TIME:20180709T100000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1741@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thanh Hoang Nhat LE (Oxford University Clinical Rese
arch Unit\, Wellcome Trust Major Overseas Programme\, Vietnam)\n*Backgroun
d*: Early fungicidal activity (EFA)\, i.e. the CSF clearance rate of quant
itative yeast culture colony counts during the first 14 days of antifungal
therapy\, is often used as the primary endpoint in phase II trials in HIV
-associated cryptococcal meningitis. While associations between EFA and su
rvival have been reported\, it is unclear whether EFA is a surrogate marke
r. \n\n*Methods*: Data from eight randomized controlled trials and four co
hort studies from Asia and Africa (23 distinct treatment and study combina
tions) were pooled. EFA was estimated based on a linear mixed effects mode
l of the longitudinal log10-CSF Cryptococcus colony forming unit (CFU) cou
nts treating values below the detection limit as left-censored. Ten-week r
isks of death were estimated with the Kaplan-Meier method. \n\n*Results*:
Data from 976 subjects contributing a total of 2851 quantitative culture m
easurements 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 a
nd 43% for fluconazole/flucytosine combinations (n=21)\, 0.35 and 38% for
amphotericin B monotherapy (n=152)\, 0.35 and 36% for amphotericin B/azo
le combinations (n=441)\, 0.49 and 26% for amphotericin B/flucytosine com
binations (n=224)\, and 0.58 and 30% for amphotericin B/flucytosine/inter
feron-gamma combinations (n=58). There was a positive correlation between
faster EFA and 10-week mortality across treatment/study combinations (R2=0
.44\, 95%CI: 0.14-0.71). However\, correlation between observed treatment
effects on EFA and 10-week mortality from randomized clinical trials (R2tr
ial=0.04\, 95%CI: 0.00-0.47\; n=620)\, and average correlations between an
individuals’ EFA and survival time within treatment/study combinations
(average squared Somers’ rank correlation R2indiv=0.07\, 95%CI: 0.04-0.1
1) were low.\n\n*Conclusion*: EFA remains a useful marker of antifungal ac
tivity but surrogacy for 10-week mortality could not be established. Limit
ations of this study are that azole and azole combination treatments were
more often used in the most resource-limited settings\, and that only one
of the included antifungal trials was powered for mortality.\n\nhttps://in
dico.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;VALUE=DATE-TIME:20180711T050000Z
DTEND;VALUE=DATE-TIME:20180711T053000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1748@indico.math.cnrs.fr
DESCRIPTION:Speakers: Thi Bao Tram NGO (PhD student)\nWe study the Multi-l
evel Monte Carlo method introduced by Giles [3] and its applications to fi
nance which is significantly more efficient than the classical Monte Carlo
method. This method for the stochastic differential equations driven by o
nly Brownian Motion had been studied by Ben Alaya and Kebaier [2]. Here\,
we consider the stochastic differential equation driven by a pure jump Lé
vy process. When the Lévy process have a Brownian component\, the speed o
f 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{equ
ation} \nX_t=x_0+\\int_0^t f(X_{s-})dY_s\, (1) \n\\end{equation} \nw
ith $f\\in\\mathcal{C}^3$ and $Y$ is a Lévy process with the triplet $(b\
,0\,F)$ and look at the asymptotic behavior of the normalized error proces
s $u_{n\,m}(X^n-X^{nm})$ where $X^n$ and $X^{nm}$ are two different Euler
approximations 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
error converges to non-trivial limit. Under some different assumptions on
the properties of the Lévy process $Y$ in $(1)$\, we found different suit
able forms of the rate $u_{n\,m}$. \n \n[1] Jean Jacod. The Euler schem
e for Lévy driven stochastic differential equations: Limit theorems. The
Annals of Probability\, 2004\, Vol.32\, No.3A\, 1830-1872. \n \n[2] Moh
amed Ben Alaya and Ahmed Kebaier. Central limit theorem for the multilevel
Monte 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. Mul
tilevel Monte Carlo for Lévy-driven SDEs: Central limit theorems for adap
tive Euler schemes. Ann. Appl. Probab.\, 26(1): 136-185\, 2016.\n\nhttps:/
/indico.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;VALUE=DATE-TIME:20180710T030000Z
DTEND;VALUE=DATE-TIME:20180710T040000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1755@indico.math.cnrs.fr
DESCRIPTION:Speakers: Quang Huy TRAN (IFPEN)\nMany applications of quantum
chemistry involve ab initio simulations. These are feasible thanks to wel
l-known approximations to the Schrödinger equation\, such as Hartree-Fock
’s or Density Functional Theory. More than 70 softwares are available to
chemists in this field\, the most common ones being VASP\, Gaussian and A
BINIT. A key difference between them lies in the basis functions selected
to express the molecular orbitals. One of the newcomers\, the massively pa
rallel program BigDFT\, uses wavelet bases for performance considerations.
\n \nTo better capture the cusp singularities of the orbitals in the all-e
lectron calculations without increasing the complexity of BigDFT\, we sugg
est enriching the wavelet basis by Gaussian functions centered at each nuc
leus position. To optimize the construction of additional Gaussian functio
ns\, we rely on a combination of a posteriori error estimates and the gree
dy algorithm. We adapt the ideas from Maday and his co-authors to establis
h that the dual norm of the residue can serve as an effective estimate for
the energy decrease between the pure-wavelet solution and the augmented-b
asis solution. Furthermore\, in a similar spirit with reduced-basis techni
ques\, we recommend the greedy algorithm for building an incremental seque
nce of additional Gaussian functions.\n \nAs a proof of concept to this st
rategy\, we investigate a one-dimensional model of Schrödinger type with
delta potentials\, which represents a system of one electron and several n
uclei of known charges and positions. Due to the small number of additiona
l degrees of freedom\, wavelet-Gaussian mixed bases exhibit a significant
gain in accuracy while having a low computational cost. This testifies to
the interest of this approach.\n\nhttps://indico.math.cnrs.fr/event/3023/c
ontributions/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;VALUE=DATE-TIME:20180710T074500Z
DTEND;VALUE=DATE-TIME:20180710T081500Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1744@indico.math.cnrs.fr
DESCRIPTION:Speakers: Nguyen Van Vuong DO (Ton Duc Thang University)\nIn t
his study\, a development of nonlinear continuum damage mechanics (CDM) mo
del for multiaxial high cycle fatigue is proposed in which the cyclic plas
ticity constitutive model has been incorporated in the finite element (FE)
framework. T-joint FE simulation of fillet welding is implemented to char
acterize sequentially coupled three-dimensional (3-D) of thermo-mechanical
FE formulation and simulate the welding residual stresses. The high cycle
fatigue damage model is then taken account into the fillet weld joints un
der the various cyclic fatigue load types to calculate the fatigue life co
nsidering the residual stresses. The fatigue crack initiation and the prop
agation in the present model estimated for the total fatigue is compared w
ith the experimental results. The FE results illustrated that the proposed
high cycle fatigue damage model in this study could become a powerful too
l to effectively predict the fatigue life of the welds. Parametric studies
in this work are also demonstrated that the welding residual stresses can
not be ignored in the computation of the fatigue life of welded structures
.\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;VALUE=DATE-TIME:20180711T041500Z
DTEND;VALUE=DATE-TIME:20180711T044500Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1747@indico.math.cnrs.fr
DESCRIPTION:Speakers: Duc Quang Bui (University Paris 13)\nParareal method
is a numerical method to solve time - evolutional problems in parallel\,
which uses two propagators: the coarse - fast and inaccurate - and the fin
e - slow but more accurate. Instead of running the fine propagator on the
whole time interval\, we divide the time space into small time intervals\,
where we can run the fine propagator in parallel to obtain the desired so
lution\, with the help of the coarse propagator and through parareal steps
. Furthermore\, each local subproblem can be solved by an iterative method
\, and instead of doing this local iterative method until convergence\, on
e may perform only a few iterations of it\, during parareal iterations. Pr
opagators then become much cheaper but sharply lose their accuracy\, and w
e hope that the convergence will be achieved across parareal iterations.
\n \nIn this talk\, we propose to couple Parareal with a well-known iter
ative method - Optimized Schwarz Waveform Relaxation (OSWR) - with only fe
w OSWR iterations in the fine propagator and with a simple coarse propagat
or deduced from Backward Euler method. We present the analysis of this cou
pled method for 1-dimensional advection reaction diffusion equation\, for
this case the convergence is almost linear. We also give some numerical il
lustrations for 1D and 2D equations\, which shows that the convergence is
much faster in practice.\n\nhttps://indico.math.cnrs.fr/event/3023/contrib
utions/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;VALUE=DATE-TIME:20180711T041500Z
DTEND;VALUE=DATE-TIME:20180711T044500Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-1763@indico.math.cnrs.fr
DESCRIPTION:Speakers: Tien Thinh NGUYEN (Gran Sasso Science Institute\, It
aly)\nDissipative hyperbolic systems play a central role in many applicati
ons including the kinetic models for gas dynamics and the relaxation numer
ical schemes approximating conservation laws. One important feature of thi
s kind of systems is the diffusion limit of solution as time tends to infi
nity. In this talk\, we will discuss some reasonable dissipative structure
s such that for large time\, the unique solution to the initial value prob
lem for\n\n$$\\partial_tu+\\sum_{j=1}^dA_j\\partial_{x_j}u+Bu=0$$\n\nis ap
proximated by a solution to the initial value problem for a parabolic syst
em\, where $A_j$ and $B$ are $n\\times n$ matrices with real constant entr
ies\, and $u=u(x\,t)$ is an $n$-dimensional real vector. The approximation
is of order $\\mathcal O\\bigl(t^{-\\frac d2(\\frac 1q-\\frac 1p)-\\alpha
}\\bigr)$ for $\\alpha\\in\\{1/2\,1\\}$ and $1\\le q\\le p\\le \\infty$\,
up to an exponentially decaying error. This optimal result in [mascianguye
n17\,nguyen18] is a generalization of [bianchini07] at the linear level. T
he main idea is based on the perturbation theory for linear operators and
the Fourier analysis.\n\nIn collaboration with Corrado Mascia (Università
di Roma 1 - Italy).\n\n[bianchini07] S. Bianchini\, B. Hanouzet and R. Na
talini\, Asymptotic behavior of smooth solutions for partially dissipative
hyperbolic systems with a convex entropy\, Comm. Pure Appl. Math.\, 60 (2
007)\, 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 dissipative
linear hyperbolic systems in several dimensions\, Discrete Contin. Dyn. Sy
st.\, (to appear).\n\nhttps://indico.math.cnrs.fr/event/3023/contributions
/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;VALUE=DATE-TIME:20180710T020000Z
DTEND;VALUE=DATE-TIME:20180710T030000Z
DTSTAMP;VALUE=DATE-TIME:20220810T074228Z
UID:indico-contribution-3023-3159@indico.math.cnrs.fr
DESCRIPTION:Speakers: Fabrice PLANCHON ()\nWe will review recent results o
n the propagation\nof waves on domains\, with emphasis on two extreme\ncas
es: the exterior or the interior of a stricly convex\ndomain. Understandin
g the wave localization\, its\namplitude and how it decays is fundamental
for\nseveral (unrelated) problems and we will describe an\ninteresting int
erplay between geometrical aspects and\ndegenerate oscillatory integrals t
hat model waves\n\nhttps://indico.math.cnrs.fr/event/3023/contributions/31
59/
LOCATION:Ho Chi Minh City University of Science
URL:https://indico.math.cnrs.fr/event/3023/contributions/3159/
END:VEVENT
END:VCALENDAR