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https://kluedo.ub.unikl.de/index/index/
Wed, 21 Jul 2010 14:10:41 +0200
Wed, 21 Jul 2010 14:10:41 +0200

Identification of Temperature Dependent Parameters in Radiative Heat Transfer
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/2216
Laserinduced thermotherapy (LITT) is an established minimally invasive percutaneous technique of tumor ablation. Nevertheless, there is a need to predict the effect of laser applications and optimizing irradiation planning in LITT. Optical attributes (absorption, scattering) change due to thermal denaturation. The work presents the possibility to identify these temperature dependent parameters from given temperature measurements via an optimal control problem. The solvability of the optimal control problem is analyzed and results of successful implementations are shown.
Oliver Tse; RenĂ© Pinnau; Norbert Siedow
preprint
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/2216
Wed, 21 Jul 2010 14:10:41 +0200

Convergent Finite Element Discretizations of the Density Gradient Equation for Quantum Semiconductors
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/1864
We study nonlinear finite element discretizations for the density gradient equation in the quantum drift diffusion model. Especially, we give a finite element description of the socalled nonlinear scheme introduced by {it Ancona}. We prove the existence of discrete solutions and provide a consistency and convergence analysis, which yields the optimal order of convergence for both discretizations. The performance of both schemes is compared numerically, especially with respect to the influence of approximate vacuum boundary conditions.
Rene Pinnau; Jorge Mauricio Ruiz
preprint
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/1864
Fri, 11 May 2007 20:46:05 +0200

The Semiconductor Model Hierarchy in Optimal Dopant Profiling
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/1781
We consider optimal design problems for semiconductor devices which are simulated using the energy transport model. We develop a descent algorithm based on the adjoint calculus and present numerical results for a ballistic diode. Further, we compare the optimal doping profile with results computed on basis of the drift diffusion model. Finally, we exploit the model hierarchy and test the space mapping approach, especially the aggressive space mapping algorithm, for the design problem. This yields a significant reduction of numerical costs and programming effort.
Concetta Drago; Rene Pinnau
preprint
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/1781
Tue, 26 Sep 2006 19:06:17 +0200

Model Reduction Techniques for Frequency Averaging in Radiative Heat
Transfer
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/1738
We study model reduction techniques for frequency averaging in radiative heat transfer. Especially, we employ proper orthogonal decomposition in combination with the method of snapshots to devise an automated a posteriori algorithm, which helps to reduce significantly the dimensionality for further simulations. The reliability of the surrogate models is tested and we compare the results with two other reduced models, which are given by the approximation using the weighted sum of gray gases and by an frequency averaged version of the socalled \(\mathrm{SP}_n\) model. We present several numerical results underlining the feasibility of our approach.
Rene Pinnau; Alexander Schulze
preprint
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/1738
Tue, 16 May 2006 14:12:20 +0200

Initial Temperature Reconstruction for a Nonlinear Heat Equation: Application to Radiative Heat Transfer
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/1607
Consider a cooling process described by a nonlinear heat equation. We are interested to recover the initial temperature from temperature measurements which are available on a part of the boundary for some time. Up to now even for the linear heat equation such a problem has been usually studied as a nonlinear illposed operator equation, and regularization methods involving Frechet derivatives have been applied. We propose a fast derivativefree iterative method. Numerical results are presented for the glass cooling process, where nonlinearity appears due to radiation.
Sergiy Pereverzyev; Rene Pinnau; Norbert Siedow
preprint
https://kluedo.ub.unikl.de/frontdoor/index/index/docId/1607
Fri, 04 Feb 2005 10:33:11 +0100