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研究生: 蔡東佐
論文名稱: 利用Γ收斂法去解決一個變異問題之研究
Γ-convergence Method for Solving a Variational Problem
指導教授: 葉麗琴
口試委員:
學位類別: 碩士
Master
系所名稱: 南大校區系所調整院務中心 - 應用數學系所
應用數學系所(English)
論文出版年: 2009
畢業學年度: 97
語文別: 中文
中文關鍵詞: 變異問題極限解Г收斂法
外文關鍵詞: variational problem, limit solutions, Г-convergence method
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  • 在這篇論文裡,我們使用形式inf∫Ω {(ε/2)k|▽u|^2+(1/4ε)(a-u)^2(b+u)^2}dx對於變異問題建構一個局部低點,這裡ε是一個很小的正參數且Ω⊂R^n是一個平滑有邊界的凸有界定義域。其中k∈C3(Ω)是在定義域Ω的閉包中的嚴格正函數。如果我們在所有函數H^1(Ω)中取最大下界,我們就會得到符合Neumann 邊界條件偏微分方程的正數解。
    我們希望限制最大下界於局部低點,因此我們考慮這Neumann問題的解在Ω上取所有正負號的值且讓它們等於零的值在(n-1)超維度表面Гε⊂Ω。藉由Г收斂法,我們從定義域Ω上的權重測線可以發現當ε→0的極限解的結構。


    In this thesis,we construct local minima of a certain variational problem which we take in the form inf∫Ω {(ε/2)k|▽u|^2+(1/4ε)(a-u)^2(b+u)^2}dx, where ε is a small positive parameter and Ω⊂R^n is a convex bounded domain with smooth boundary. Here k∈C3(Ω) is strictly positive functions in the closure of the domain Ω. If we take the inf over all functions H^1(Ω), we obtain the positive solution of the partial differential equation with Neumann boundary conditions.
    We wish to restrict the inf to local (not global) minima so that we consider solutions of this Neumann problem which take both signs in and which vanish on (n-1) dimensional
    hypersurfaces Гε⊂Ω. By using a Г-convergence method, we nd the structure of the limit solutions as ε→0 in terms of the weighted geodesics of the domain Ω.

    1. Introduction 1 2. Function of Bounded Variation 4 3. Local minimisers of the energy functional 10 4. Proof of Properties 14 5. Bibliography 22 6. Appendix 24

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    [6] Kosaku Yosida, Functional Analysis, Heidelberg, Germany, 1995.
    [7] L.C. Yeh & J. Norbury, Variational problems with singular perturbation, Nonlinearity, 66 (2007) 51-61.
    [8] N.C. Owen and P. Sternberg, Nonconvex variational problems with anisotropic perturbations, Nonlinear Anal. theory Methods & Appl. 16 (1991) 705-719.
    [9] P. Sternberg, The effect of a singular perturbation on nonconvex variational problems, Arch. Rational. Mech. Anal. 101 (1988) 209-240.
    [10] R.V. Kohn and P. Sternberg, Local minimizers and singular perturbations, Proc. Roy. Soc. Edinburgh Sect. A, 111 A (1989) 69-84.
    [11] S.M. Allen & J.W.Cahn, A microscopic theory for antiphase boundary motion and its application to antiphase domain coarsening, Acta Met. 27 (1979) 1085-1095.

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