ترغب بنشر مسار تعليمي؟ اضغط هنا

Determine the source term of a two-dimensional heat equation

115   0   0.0 ( 0 )
 نشر من قبل Alain Pham Ngoc Dinh
 تاريخ النشر 2008
  مجال البحث
والبحث باللغة English
 تأليف Dang Duc Trong




اسأل ChatGPT حول البحث

Let $Omega$ be a two-dimensional heat conduction body. We consider the problem of determining the heat source $F(x,t)=varphi(t)f(x,y)$ with $varphi$ be given inexactly and $f$ be unknown. The problem is nonlinear and ill-posed. By a specific form of Fourier transforms, we shall show that the heat source is determined uniquely by the minimum boundary condition and the temperature distribution in $Omega$ at the initial time $t=0$ and at the final time $t=1$. Using the methods of Tikhonovs regularization and truncated integration, we construct the regularized solutions. Numerical part is given.



قيم البحث

اقرأ أيضاً

In this work, an inverse problem in the fractional diffusion equation with random source is considered. Statistical moments are used of the realizations of single point observation $u(x_0,t,omega).$ We build the representation of the solution $u$ in integral sense, then prove some theoretical results as uniqueness and stability. After that, we establish a numerical algorithm to solve the unknowns, where the mollification method is used.
We consider the nonlinear Schrodinger equation [ u_t = i Delta u + | u |^alpha u quad mbox{on ${mathbb R}^N $, $alpha>0$,} ] for $H^1$-subcritical or critical nonlinearities: $(N-2) alpha le 4$. Under the additional technical assumptions $alphageq 2$ (and thus $Nleq 4$), we construct $H^1$ solutions that blow up in finite time with explicit blow-up profiles and blow-up rates. In particular, blowup can occur at any given finite set of points of ${mathbb R}^N$. The construction involves explicit functions $U$, solutions of the ordinary differential equation $U_t=|U|^alpha U$. In the simplest case, $U(t,x)=(|x|^k-alpha t)^{-frac 1alpha}$ for $t<0$, $xin {mathbb R}^N$. For $k$ sufficiently large, $U$ satisfies $|Delta U|ll U_t$ close to the blow-up point $(t,x)=(0,0)$, so that it is a suitable approximate solution of the problem. To construct an actual solution $u$ close to $U$, we use energy estimates and a compactness argument.
We have shown in a recent collaboration that the Cauchy problem for the multi-dimensional Burgers equation is well-posed when the initial data u(0) is taken in the Lebesgue space L 1 (R n), and more generally in L p (R n). We investigate here the sit uation where u(0) is a bounded measure instead, focusing on the case n = 2. This is motivated by the description of the asymptotic behaviour of solutions with integrable data, as t $rightarrow$ +$infty$. MSC2010: 35F55, 35L65. Notations. We denote $times$ p the norm in Lebesgue L p (R n). The space of bounded measure over R m is M (R m) and its norm is denoted $times$ M. The Dirac mass at X $in$ R n is $delta$ X or $delta$ x=X. If $ u$ $in$ M (R m) and $mu$ $in$ M (R q), then $ u$ $otimes$ $mu$ is the measure over R m+q uniquely defined by $ u$ $otimes$ $mu$, $psi$ = $ u$, f $mu$, g whenever $psi$(x, y) $ otequiv$ f (x)g(y). The closed halves of the real line are denoted R + and R --. * U.M.P.A., UMR CNRS-ENSL # 5669. 46 all{e}e dItalie,
123 - Slim Tayachi , Hatem Zaag 2015
We consider the nonlinear heat equation with a nonlinear gradient term: $partial_t u =Delta u+mu| abla u|^q+|u|^{p-1}u,; mu>0,; q=2p/(p+1),; p>3,; tin (0,T),; xin R^N.$ We construct a solution which blows up in finite time $T>0.$ We also give a sharp description of its blow-up profile and show that it is stable with respect to perturbations in initial data. The proof relies on the reduction of the problem to a finite dimensional one, and uses the index theory to conclude. The blow-up profile does not scale as $(T-t)^{1/2}|log(T-t)|^{1/2},$ like in the standard nonlinear heat equation, i.e. $mu=0,$ but as $(T-t)^{1/2}|log(T-t)|^{beta}$ with $beta=(p+1)/[2(p-1)]>1/2.$ We also show that $u$ and $ abla u$ blow up simultaneously and at a single point, and give the final profile. In particular, the final profile is more singular than the case of the standard nonlinear heat equation.
We prove logarithmic stability in the parabolic inverse problem of determining the space-varying factor in the source, by a single partial boundary measurement of the solution to the heat equation in an infinite closed waveguide, with homogeneous initial and Dirichlet data.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا