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研究生: 高昱璋
Kao, Yu-Chang
論文名稱: 從橢圓區域的邊界上的測量去偵測區域內部的橢圓狀未知物之數值實驗—二維情況
Some Numerical Experiments on Detecting an Unknown Elliptical Obstacle from the Boundary Measurements in an Elliptical Region—2D Case
指導教授: 關汝琳
Kuan, Ru-Lin
學位類別: 碩士
Master
系所名稱: 理學院 - 數學系應用數學碩博士班
Department of Mathematics
論文出版年: 2026
畢業學年度: 114
語文別: 英文
論文頁數: 133
中文關鍵詞: 包圍法反問題邊界測量未知物位置電流密度電壓橢圓狄利克雷邊界條件紐曼邊界條件
外文關鍵詞: enclosure method, inverse problem, boundary measurement, the position of unknown obstacle, current density, voltage, ellipse, Dirichlet boundary condition, Neumann boundary condition
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  • 鑒於 Masaru Ikehata 教授的論文 [5] 中所講述的包圍法(enclosure method)和蔡佩旻的論文 [12] 的啟發,本研究旨在探討如何利用在區域邊界測量的資訊來判斷鑲嵌於背景區域中的未知阻礙物之位置。具體來說,我們將背景區域設定為一個橢圓狀區域,並在其中嵌入另一個橢圓形阻礙物。對於該橢圓狀阻礙物,其位置、大小以及旋轉角度皆可自由調整。此外,我們亦考慮不含阻礙物之背景區域作為對照情況。針對上述兩種情況,我們分別在對應的區域上定義拉普拉斯方程(Laplace equation)。在兩個問題中,皆於背景區域的外邊界施加狄利克雷邊界條件(Dirichlet boundary condition);而對於含有阻礙物的情況,則於此阻礙物的邊界設定紐曼邊界條件(Neumann boundary condition)。值得注意的是,所施加的狄利克雷邊界資訊(在物理學上可視為電壓,參考 [8] 第 12 章)會在背景區域邊界產生相對應的法向導數資訊(在物理學上可視為電流,參考 [8] 第 12 章)。透過結合上述兩大偏微分方程問題,我們進行大量數值實驗,以探討出邊界量測資訊與內部橢圓形阻礙物的位置之間的關聯性。藉由分析這些關聯,我們期望在未來能夠根據新給定的邊界量測資料來推測未知阻礙物在區域中的位置,是為反問題(inverse problem)。

    In the light of [12] as well as Masaru Ikehata’s paper [5], the goal of my research is to find out the position of some unknown obstacle embedded in a background region. Particularly, we set up the background region to be an elliptical region containing an elliptical region (obstacle). For the elliptical obstacle, we can adjust its position, size and the angle of rotation. Besides, we also consider the counterpart that has no obstacle in the background region. For the two situations, we define Laplace equation in both domains. For the two problem, we set Dirichlet boundary conditions on the boundary of background region; for the problem associated with the domain containing an obstacle, we specify a Neumann boundary condition on the boundary of the obstacle. It is important that the input Dirichlet data (in physics, voltage, see the chapter 12 of [8]) will generate normal derivative data on the boundary of background (in physics, current density, see the chapter 12 of [8]). Combining the two, we carry out a great amount of numerical experiments to find out some relationship between boundary measurement information and the position of the elliptical obstacle. With the relationship, in the future when we’re given a number of boundary measurement data, we can accordingly deduce the position of the obstacle. This is a kind of inverse problem.

    1 Introduction 1 1.1 Our Background and Goal 1 1.2 Motivations 4 1.2.1 Enclosure Method from [5] and a viewpoint taken reference from chapter 12 of [8] and chapter 7 of [10] 4 1.2.2 A difficulty of implementing enclosure method to practical problems 11 1.2.3 Inspiration from [12] 12 1.2.4 Our Experiments 12 2 Our Goal and Plan 13 3 Our Technique, Numerical Experiments and Observation 20 3.1 Our Techniques — The Idea Behind Our MATLAB Codes and Strategy to Observe Numerical Results 20 3.1.1 The settings and the procedures of our codes 21 3.1.2 The Scheme of Observing Numerical Experiments 24 3.2 Numerical Experiment I : a = 1.5, b = 0.675 46 3.2.1 First Path 46 3.2.2 Second Path 49 3.2.3 Third Path 51 3.2.4 Fourth Path 52 3.2.5 Fifth Path 54 3.2.6 Sixth Path 56 3.2.7 Seventh Path 57 3.2.8 Eighth Path 59 3.2.9 Graph 61 3.3 Numerical Experiment II : a = 1, b = 0.45 61 3.3.1 First Path 61 3.3.2 Second Path 63 3.3.3 Third Path 65 3.3.4 Fourth Path 66 3.3.5 Fifth Path 68 3.3.6 Sixth Path 70 3.3.7 Seventh Path 71 3.3.8 Eighth Path 74 3.3.9 Graph 76 3.4 Numerical Experiment III : a = √1.2, b = √2.7 76 3.4.1 First Path 76 3.4.2 Second Path 78 3.4.3 Third Path 80 3.4.4 Fourth Path 81 3.4.5 Fifth Path 83 3.4.6 Sixth Path 85 3.4.7 Seventh Path 86 3.4.8 Eighth Path 88 3.4.9 Graph 90 3.5 Numerical Experiment IV : a = b = √1.8 91 3.5.1 First Path 91 3.5.2 Second Path 92 3.5.3 Third Path 93 3.5.4 Fourth Path 94 3.5.5 Fifth Path 95 3.5.6 Sixth Path 97 3.5.7 Seventh Path 98 3.5.8 Eighth Path 99 3.5.9 Graph 100 3.6 Numerical Experiment V : a = b = √1.0125 101 3.6.1 First Path 101 3.6.2 Second Path 102 3.6.3 Third Path 103 3.6.4 Fourth Path 104 3.6.5 Fifth Path 105 3.6.6 Sixth Path 107 3.6.7 Seventh Path 108 3.6.8 Eighth Path 109 3.6.9 Graph 110 4 Comparisons, Summary and Conjectures 111 4.1 Comparison between Our Numerical Experiments—Similar Ellipses with Different Sizes 111 4.2 Comparison between Our Numerical Experiments—Ellipses with SameArea 112 4.3 Comparison Between our research with [12] 113 4.3.1 Similarities and differences between our research and [12] 113 4.3.2 View [12] as an analogue of our research 114 4.4 Comparison between our research and partial contents in chapter 12 ∼ 13 of [8] 115 4.5 Summaries and Conjectures 116 4.5.1 Summaries 116 4.5.2 Conjectures 117 5 Future Research 119 Reference 121

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    [12] 蔡佩旻. 從邊界測量去偵測矩形電阻網路中未知孔洞的位置的數值實驗 = numerical experiments on the detection of the unknown cavities in rectangular resistor network from boundary measurement. Master’s thesis, 國立成功大學, 2022.

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