1,721,153 research outputs found
Simulation of Optical Coherence Tomography by Using Finite-Difference Time-Domain Method
No full text摘要學相干層析技術（ OCT ）是一種顯微鏡方法，現在已經獲得了普及。這是一個光學信號採集和處理方法，使一個非常高品質，高分辨率（微米級） ，並有能力生產三維圖像內光散射媒體得到的。華僑城被廣泛應用於醫學領域特別是在觀測的生物組織，但它也可用於光子的高精度測量。一些華僑城優點是高分辨 率和高還深穿透。本華僑城是干涉。我們使用低相干光作為光源。在這裡，我們嘗試診斷鑑於這是來自樣品臂的光從參考臂用的原則，邁克耳孫干涉儀。相結合的反射光從樣品臂和參考臂將產生干涉模式只有輕武器都走過了同樣優秀的光學距離。這意味著雙方將有相同的光學路徑長度。 正的華僑城模擬，但是，有一個限制的條件，地點和材料，目前正在觀察。為了簡化這個問題，我們嘗試以模擬10月利用有限差分時域（ FDTD法）方法。這種模擬方法使我們能夠建立一個範例，我們需要的材料，並提出了假設情況，適合觀測的材料是很難在現實世界中。在此模擬，我們建立了一 個樣本材料，然後嘗試建造一個代表性的形象材料。若干假設是用於這一模擬實現一個更好的結果的目的。Abstractptical Coherence Tomography (OCT) is a kind of microscopy method that has gained popularity nowadays. It is an optical signal acquisition and processing method that allowed an extremely high-quality, high resolution (micrometer scale), and ability to produce a three-dimensional images from within optical scattering media to be obtained. OCT is widely used in medical field especially in observing the biological tissue, although it is also can be used in photonics for a high precision measurement. Some of OCT advantages are high resolution and also deep penetration.he basic of OCT is interferometry. We use a low coherence light as the light source. Here we try to diagnose the light that is coming from the sample arm with the light from reference arm by using the principle of Michelson interferometer. The combination of reflected light from the sample arm and the reference arm will give rise to an interference pattern only if light from both arms have travelled in the same optical distance. It means that both will have the same optical path length. he real OCT simulation, however, has a limitation from the condition of the place and the material that is being observed. To simplify this problem, we try to simulate the OCT by using the Finite-Difference Time-Domain (FDTD) method. This simulation method allow us to construct a sample material that we need and made a scenario that is suitable for observing the material that is difficult in the real world. In this simulation, we build a sample material and then try to construct a representation of image of the material. Several assumptions are used for this simulation to achieve a better result in the end.ontentsContentscknowledgements 2bstract 3ontents 4igure contents 6hapter 1 Introduction 9.1 Introduction of Optical Coherence Tomography 9.2 Working Principles of OCT 10.3 Content 13hapter 2 Basic of Optical Light Interaction and Microscopy Method 15.1 Introduction to Microscopy Method 15.2 Interference Phenomenon 19.3 Introduction of OCT Method 23hapter 3 FDTD Method 34.1 Introduction to FDTD Method 34.2 Courant Limit 44.3 Scattered-Field Total-Field 45.4 Absorbing Boundary Conditions and Perfectly Matched Layer 50hapter 4 Method and Experiment 57.1 Basic Scheme 57.2 Simulation Parameters 60.3 Simulation Scheme and Assumptions 64.4 Validation 66.5 Simulation Results 68.6 Summaries 95hapter 5 Conclusions and Future Works 97.1 Conclusions 97.2 Future Works 98eferences 100igure contentsig. 2-1 Bright-field microscopy……..……………………..………………………….16ig. 2-2 Dark-field Microscopy…………………..……..…………………………..….17ig. 2-3 Mathematical description of wave……………..……………………...……....20ig. 2-4 Diffraction phenomenon………………..……………………..……................21ig. 2-5 Thomas Young’s double-slit experiment...........................................................22ig. 2-6 Linear connection in interference phenomenon………………..…………..….23ig. 2-7 Michelson interferometer……………….…………………………...………...24ig. 2-8 Comparison between fully broadband, fully monochromatic, and low coherence light source….........................................................................................……...25ig. 2-9 Comparison between Confocal Microscopy, OCT, and Ultrasound….…….....26ig. 2-10 OCT system…………………………………..……………..…...…………...27ig. 2-11 Time Domain and Frequency Domain OCT….………….....…...…………...29ig. 2-12 FD-OCT with Spectrometer…………..…………...………..…...…………...31ig. 2-13 Frequency Domain OCT with swept laser.…...………………………….......31 ig. 3-1 Yee Grid…………………………………………………...…………….…….36ig. 3-2 Leapfrog arrangement of FDTD………………………...…………………….37ig. 3-3 Description of the Scattered Field-Total Field…………...…............................46ig. 3-4 MATLAB simulation on SFTF..........................................................................47ig. 3-5 Illustration of PML............................................................................................53ig. 4-1 The system of OCT……………........................................................................57ig. 4-2 Cross sectional imaging & en face imaging......................................................58ig. 4-3 Sample of OCT image........................................................................................60ig. 4-4 Depth and intensity relation ……......................................................................63ig. 4-5 Simplified OCT system…..................................................................................64ig. 4-6 Simulation field for validation...........................................................................66ig. 4-7 Radar Cross Section (RCS) for FDTD code......................................................67ig. 4-8 Radar Cross Section (RCS) for Mie theory........................................................67ig. 4-9 Simulation field..................................................................................................68ig. 4-10 Simulation field for square structure................................................................70ig. 4-11 The detected Ez field as function of time.........................................................70ig. 4-12 The normalized intensity of Ez as function of time.........................................71ig. 4-13 Plot of intensity vs. time in square structure....................................................71ig. 4-14 Simulation field for bar structure.....................................................................72ig. 4-15 The detected Ez field as function of time…....................................................72ig. 4-16 The normalized intensity of Ez as function of time.........................................73ig. 4-17 Plot of intensity vs. time in bar structure.........................................................73ig. 4-18 Simulation field for triangle structure..............................................................74ig. 4-19 The detected Ez field as function of time........................................................74ig. 4-20 The normalized intensity of Ez as function of time.........................................75ig. 4-21 Plot of intensity vs. time in triangle structure..................................................75ig. 4-22 Simulation field for circle structure.................................................................76ig. 4-23 The detected Ez field as function of time........................................................76ig. 4-24 The normalized intensity of Ez as function of time.........................................77ig. 4-25 Plot of intensity vs. time in circle structure.....................................................77ig. 4-26 Material with bar shape in both horizontal and vertical direction...................81ig. 4-27 Normalized intensity on both bar shape material in horizontal and verticalirection............................................................................................................82ig. 4-28 The detected Ez field as function of time for 1st scenario................................84ig. 4-29 The normalized intensity of Ez as function of time for 1st scenario................84ig. 4-30 The detected Ez field as function of time for 2nd scenario...............................85ig. 4-31 The normalized intensity of Ez as function of time for 2nd scenario...............85ig. 4-32 The detected Ez field as function of time for 3rd scenario...............................86ig. 4-33 The normalized intensity of Ez as function of time for 3rd scenario................86ig. 4-34 The detected Ez field as function of time for 4th scenario...............................87ig. 4-35 The normalized intensity of Ez as function of time for 4th scenario................87ig. 4-36 Normalized intensities detected only from the front interface of the material..........................................................................................................89ig. 4-37 Normalized intensities detected from whole of the material...........................90ig. 4-38 Simulation field of 1st irregular structur...........................................................91ig. 4-39 The detected Ez field as function of time for 1st irregular structure................91ig. 4-40 Simulation field of 1st irregular structure.........................................................92ig. 4-41 The detected Ez field as function of time for 2nd irregular structure...............92ig. 4-42 Simulation field of 3rd irregular structure........................................................93ig. 4-43 The detected Ez field as function of time for 3rd irregular structure................93ig. 4-44 Simulation field of 4th irregular structure.........................................................94ig. 4-45 The detected Ez field as function of time for in 4th irregular structure............9
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Rancang Bangun Mesin Perajang Tembakau Dengan Kapasitas 30 Kg/Jam
No full textSebagaimana telah diketahui bahwa teknologi dengan bantuan mesin dapat
mempercepat kinerja manusia dalam melakukan aktifitas. Hal ini memberikan ide
untuk memperbaiki sistem kerja, bahkan membuat alat/mesin guna mendapatkan
kesempurnaan sistem kinerja tersebut.Pembuatan suatu mesin sesungguhnya
didahului dengan perencanaan atau rancangan suatu mesin kemudian dapat
dilanjutkan atau direalisasikan dalam perancanaan, yaitu dalam bentuk
sesungguhnya. Untuk mendapatkan suatu rancang bangun yang baik dan berhasil
tergantung dari berbagai faktor, diantaranya adalah kemampuan mesin untuk
membuat kinerja yang berkualitas, memenuhi kapasitas produk, keserasian dalam
bentuk dan desainnya juga harus menarik, mesin tersebut harus gampang
dioperasikan, mudah dalam pemeliharaan yang meliputi perawatan dan perbaikan,
dan harganya juga harus terjangka. Adapun tujuan rancang bangun ini adalah agar
mampu merancang dan membuat mesin perajang tembakau dengan hasil yang
baik,daya motoryang terpasang adalah 0,25Hp. Dengan kapasitas 30 Kg/ja
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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