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研究生:林宜芳
研究生(外文):Yi-Fang Lin
論文名稱:電容式電腦斷層掃描成像原理及電極間電場理論研究
論文名稱(外文):A study of the imaging method for electrical capacitance tomography and the soft effects between electrodes.
指導教授:白敏賢
指導教授(外文):Miin-Shyan Bair
學位類別:碩士
校院名稱:義守大學
系所名稱:電子工程學系
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2001
畢業學年度:89
語文別:中文
論文頁數:107
中文關鍵詞:電容式電腦斷層掃描系統電場軟性效應代數重建演算法
外文關鍵詞:Electrical Capacitance TomographySoft effectAlgebraic Reconstruction Technique
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本研究探討電容式電腦斷層掃描系統Electrical Capacitance Tomography (ECT)多電極間感應區內的電場非線性效應及影像重建法則。以電磁場模擬系統Opera-2D模擬分析系統的靈敏度,以及模擬電容值。並以Microsoft Visual C++程式開發環境重建感應區的介電常數分佈,以及顯示重建的影像。
主要有兩項因素會影響ECT系統的解析度,其一是電場效應,由於感應區內物體的形狀、面積大小、以及位置會影響電場效應,對電極間電容量測值產生影響。另一因素是重建演算法,因為演算方式不同,重建後介電常數分佈會受到重建法則的特性影響。
本研究探討異質物質產生的電場交互作用,證實電場軟性效應(softeffcet)確實存在,並以電容值變化量分析電場軟性效應。以可獲得相對介電常數值的SBP二階段非線性轉換演算法,重建初步影像。並以可得到絶對介電常數值的遞迴式影像重建演算法Algebraic Reconstruction Technique (ART)二階段非線性轉換演算法,重建得影像。將電場軟性效應分析得到的softeffect factor加入系統靈敏度中,重建影像,重建的影像品質獲得改善。

This research explores electrical field effect and reconstruction algorithm for the Electrical Capacitance Tomography (ECT) system. The electromagnetic simulation package: Opera-2D is used to analyse the sensitivity of the system and the capacitance measurement. The Microsoft Visual C++ environment is employed to reconstructe the permittivity in the sense area and display the reconstruction image.
There are two major effects will affect the resolution of the reconstructed image. One is the interaction of the electrical field due to the position, shape and the size of objects in the sensing area. The effects will influence the capacitance measurements between electrodes. Another one is the reconstruction algorithm because the distinct algorithms have different characteristic and so as to the reconstructed images.
This research explores the soft effect showing that the shapes, position and existence of the object or objects in the sensing area will affect the capacitance change.
The prototype images for the typical flows have been reconstructed by using Simple Back Projection and Algebraic Reconstruction Technique methods. SBP method generates relative value of permittivity and ART method generates absolute value of permittivity. The soft effects, studied in the research, have been integrated into both the SBP and the ART methods. Better images quality is shown in the images by either reconstruction method.

中文摘要…………………………………………………………………….……...Ⅰ
英文摘要………………………………………………………………………..…..Ⅱ
致謝………………………………………………………………………….….…..Ⅳ
目錄………………………………………………………………………….….…..Ⅴ
圖表目錄……………………………………………………………………………IX
符號表………………………………………………………………………….…XIV
第一章緒論……………………………………………………………………..…1
1.1前言……………………………………………….……………..…...1
1.2歷史沿革…………………………………………….…………..…...1
1.3章節簡介………………………………………….……………….....2
第二章電場原理與模擬系統分析…………………………………….………….3
2.1靜電場內的介電質………………………………………………......3
2.1.1 介電質的極化……………………………….……..…...…3
2.1.2 電通密度與介電常數…………………………….……….5
2.1.3 邊界條件……………………………..………………...….7
2.1.4 極化向量…………………………...…………………….. 8
2.2電磁場模擬系統…………………………….…………………...….10
2.2.1 Opera-2D電磁場模擬系統……….……..….………...….10
2.2.2 Opera-2D電磁場模擬軟體的參數限制……………...….11
第三章電場的軟性效應....……………………………………………………....12
3.1 平行電極……………………………………………….……………12
3.2 平行電場感應區內的軟性效應( Soft Effect )……..……………….13
3.3 非平行電場感應區內的軟性效應( Soft Effect )……………..…….16
第四章ECT系統分析…………………………………………………………...19
4.1 電容式電腦斷層掃描系統…………………….……………………19
4.1.1 ECT架構內容………………………………...……….…20
4.1.2 系統順向分析……………………………………………20
4.1.3 系統回溯分析……………………………………………21
4.2 感應的架構與感應區像素形狀……………………….……………21
4.2.1 電極架構…………………………………………………21
4.2.2 感應區像素的形狀………………………………….…...22
4.3 電容值的分析……………………….………………………………23
4.4 系統的靈敏度……………………………..………………………...26
4.4.1 靈敏度…………..…………………………..……………26
4.4.2 多電極系統靈敏度…..……………………………….….27
4.5 系統電容估測值…………………………………………………….31
4.5.1一階Sensitivity的電容估測值………………………….31
4.5.2二階Sensitivity的電容估測值………………………….33
4.5.3電容估測值與電容模擬值的比較………………………39
第五章影像重建演算法………………..…………………….………………….42
5.1SBP演算法………………………………….………………..…….42
5.1.1 SBP演算法分析………………………………..…...…...42
5.1.2 以SBP演算法則重建,系統靈敏度不含軟性效應…...43
5.1.3 以SBP演算法則重建,系統靈敏度含軟性效應………50
5.2ART演算法…………………………………………………………55
5.2.1 ART演算法分析…………………………………………55
5.2.2 以ART演算法則重建,系統靈敏度不含軟性效應…...58
5.2.3 以ART演算法則重建,系統靈敏度含軟性效應……...66
5.3 重建影像的影像品質分析………………………………………….72
5.3.1 品質分析…………………………………………………72
5.3.2 以SBP演算法重建影像的品質分析…………………...73
5.3.3 以ART演算法重建影像的品質分析…………………..75
5.3.4 綜合分析SBP與ART重建影像的品質……………….76
5.4 感應區像素數量與解析度的關係………………………………….77
5.4.1 以1024個像素為基礎的ECT系統……………………….78
5.4.2 增加像素後重建影像的品質分析…………………………78
第六章結論與討論…………………………………………….…….…………. 81
6.1研究結果討論…………………….……………………..……….…81
6.1.1 電場效應………………………..…………………...…...81
6.1.2 影像重建演算法……………………..…………...….…..82
6.2未來研究方向…………………………………………..….…….…85
參考文獻………………………………………………….………………..….……86
附件一 電容量測值………………………………………………………...…….89
附件二 VC++程式計算電容預測值……………………………………………..91
附件三 VC++程式計算Sensitivity………………………………………..….….93
附件四 VC++程式SBP演算法………………………………………….….…...95
附件五 VC++程式ART演算法……………………………………….……...…96
附件六 Matlab程式顯示3-D重建圖形……………………………………..…..98
附件七 Opera-2D模擬分析ECT系統…………………………..………………99

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