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1
Content available Identification of thermophysical parameters using an artificial immune system
Dziatkiewicz Jolanta, Poteralski Arkadiusz
Computer Assisted Methods in Engineering and Science
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2023
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Vol. 30, no. 4
521--537
EN
In this paper, the identification of thermophysical parameters using the hyperbolic twotemperature model is made. We investigate the influence of ultra-fast laser pulses on the heating of a thin metal film using this model. Two differential equations coupled with the electron-phonon coupling factor G are used. One of these equations concerns electron temperatures and the other addresses lattice temperatures. Appropriate initial and boundary conditions are imposed for this model. The finite difference method with a staggered grid is used to solve this direct problem. Temperatures for even nodes and heat fluxes for odd nodes are calculated. The results of the direct problem and results of the experiment are compared. In the optimization process, an artificial immune system is used.
2
Content available Analysis of ultrashort laser pulse interactions with metal films using a two-temperature model
Majchrzak E., Dziatkiewicz J.
Journal of Applied Mathematics and Computational Mechanics
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2015
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Vol. 14, nr 2
31--39
EN
In the paper the problem of thin metal film subjected to the action of the high laser fluence and the ultrashort pulse width is considered. The mathematical model consists of the equations describing the electrons and phonons temperatures and the relationships between the heat fluxes and temperature gradients of electrons and phonons. The problem is solved using the explicit scheme of the finite difference method with staggered grid. In the final part the results of computations and conclusions are presented.
3
Content available remote Application of sensitivity analysis in microscale heat transfer
Majchrzak E., Dziatkiewicz J., Kałuża G.
Computer Assisted Methods in Engineering and Science
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2013
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Vol. 20, no. 2
113--121
EN
In the paper, the thin metal film subjected to the ultrashort laser pulse has been analyzed. The heat conduction in the domain considered has been described by two-temperature model consisting of the system of two coupled parabolic equations determining the electron and lattice temperatures. The sensitivity analysis of electron and lattice temperatures with respect to the parameters appearing in mathematical description has been discussed. In particular, the changes of temperatures due to the changes of coupling factor G and the film thickness L have been estimated. At the stage of numerical computations in a case of basic as well as sensitivity problems solutions the explicit scheme of finite difference method has been used. In the final part of the paper the results of computations have been shown.
4
Analiza wrażliwości cienkiej warstwy metalowej poddanej działaniu lasera
Majchrzak E., Dziatkiewicz J., Kałuża G.
Modelowanie Inżynierskie
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2012
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T. 12, nr 43
155-160
PL
Rozpatrywano cienką warstwę metalową poddaną działaniu lasera o ultrakrótkim impulsie. Przewodzenie ciepła w warstwie opisano za pomocą modelu dwutemperaturowego składającego się z układu dwóch sprzężonych równań parabolicznych określających temperaturę gazu elektronowego i sieci krystalicznej. Przeprowadzono analizę wrażliwości pól temperatury ze względu na grubość warstwy. W tym celu wykorzystano podejście bezpośrednie analizy wrażliwości kształtu z zastosowaniem pochodnej materialnej. Pokazano wyniki obliczeń oraz sformułowano wnioski.
EN
The thin metal film subjected to the ultrashort laser pulse has been considered. The heat conduction in thin film has been described by two-temperature model consisting of the system of two coupled parabolic eąuations determining the electron and lattice temperatures. The sensitivity analysis of temperature fields with respect to the film thickness has been done. To this end the direct approach of shape sensitivity analysis using the concept of material derivative has been applied. The results of computations have been shown and the conclusions have been formulated.
5
Content available remote Identification of electron-phonon coupling factor in a thin metal film subjected to an ultrashort laser pulse
Majchrzak E., Dziatkiewicz J.
Computer Assisted Methods in Engineering and Science
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2012
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Vol. 19, no. 4
383--392
EN
A thin metal film subjected to a laser pulse is considered. The problem is described by the system of energy equations describing the electron gas and lattice temperatures. The thermal interactions between electrons and lattice are determined by the parameter G called the electron-phonon coupling factor. To estimate the unknown parameter G the identification problem is formulated. The additional information necessary to solve an inverse problem is the knowledge of transient measurements of the reflectivity or transmissivity variation which is proportional to the variation of the electron temperature. So, at the stage of inverse problem solution, it is possible to assume the knowledge of electrons temperature on the irradiated surface of the system (x = 0). To solve the identification problem the gradient method basing on the least squares criterion and sensitivity coefficients is used. In the final part of the paper the results of computations are shown
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