Quasilinear parabolic problems with nonlinear boundary conditions
Quasilinear parabolic problems with nonlinear boundary conditions
Quasilinear parabolic problems with nonlinear boundary conditions
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we have to show that there exist c > 0 and η ∈ (0, π/2) such that the inequality<br />
�<br />
� � �<br />
�<br />
�<br />
1 � �<br />
� + 2�<br />
� 1<br />
â(z)τ 2 � ≤ c � +<br />
�â(z)τ<br />
2<br />
�<br />
� 1<br />
â(z)τ 2 + 1<br />
4ˆb(z)+ 4<br />
3 â(z)<br />
ˆ 4<br />
b(z)+ 3 â(z)<br />
�<br />
1<br />
â(z)τ 2 + 1 + �<br />
1<br />
( ˆb(z)+ 4<br />
3<br />
�<br />
�<br />
�<br />
�<br />
�<br />
+ 1�<br />
â(z))τ 2 �<br />
, (z, τ) ∈ Σ π<br />
2 +η × Ση<br />
holds true; here Σθ = {λ ∈ C \ {0} : |arg λ| < θ}. This crucial estimate is obtained by a<br />
careful function theoretic analysis.<br />
Finally, in Chapter 6 we study the <strong>nonlinear</strong> problem (1.1) described at the beginning<br />
and prove the last main result of the present thesis, Theorem 6.1.2, by means of the<br />
contraction mapping principle employing the optimal regularity results obtained for the<br />
linear problem (1.19). Section 6.1 deals <strong>with</strong> the fixed point construction and the basic<br />
estimates. It also contains the list of all assumptions needed for our treatment of (1.1).<br />
The proof of the harder estimates concerning in particular the <strong>nonlinear</strong>ities on the<br />
<strong>boundary</strong> is deferred to Section 6.2.<br />
Acknowledgements. In the first place, I would like to express my gratitude to my<br />
supervisor, Prof. Dr. Jan Prüss. He is always open for discussing <strong>problems</strong> and an excellent<br />
teacher to me. I am also indebted to him for the participation in numerous national<br />
and international workshops and conferences. I am grateful to my colleagues, PD Dr.<br />
Roland Schnaubelt and Dipl.-Math. Matthias Kotschote, for many fruitful discussions<br />
and valuable suggestions. I would like to thank the Studienstiftung des deutschen Volkes,<br />
Bonn, for financial and non-material support. The thesis was also partially financially<br />
supported by a grant of the Graduiertenförderung des Landes Sachsen-Anhalt. I am<br />
grateful to Dr. Nina Grosser who critically and carefully read the manuscript of this<br />
work. I cannot forget all my friends who accompanied me during the last years. Finally,<br />
I would like to express my most sincere thanks to my parents for their constant support<br />
in every respect.<br />
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