Browsing by Issue Date, starting with "2013-06-14"

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A theoretical study on the strong-field ionization of the lithium atom
(2013-06-14)
Jheng, Shih-Da
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Jiang, T. F.
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物理研究所
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Institute of Physics
We apply a recently developed momentum space method (Jiang et al 2012 Phys. Rev. E 86 066702) to investigate the experimental results of strong-field ionization of the lithium atom (Schuricke et al 2011 Phys. Rev. A 83 023413). By splitting the photoelectron into groups of even and odd angular momenta and by using the states' population history, we can analyse the ionization mechanism in further detail. The lower energy double-peak structure, shown experimentally, of the photoelectron is attributed to the three-level Lambda-coupling effect. The spectral difference of 10 and 30 fs pulses at a typical intensity is demonstrated. We explain why the strong-field ionization fluctuates at intensities of 6 and 10 fs, but not for a 30 fs pulse. The change of fan-like photoelectron angular distribution with intensity in direction parallel to polarization is explained. Use of the Keldysh parameter to classify the tunnelling and multiphoton ionization is not meaningful for the lithium atom, because the ground state is mostly depleted before reaching peak intensity.
VBM reveals brain volume differences between Parkinson's disease and essential tremor patients
(2013-06-14)
Lin, Ching-Hung
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Chen, Chun-Ming
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Lu, Ming-Kuei
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Tsai, Chon-Haw
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Chiou, Jin-Chern
Symptoms of essential tremor (ET) are similar to those of Parkinsons disease (PD) during their initial stages. Presently, there are few stable biomarkers available on a neuroanatomical level for distinguishing between these two diseases. However, few investigations have directly compared the changes in brain volume and assessed the compensatory effects of a change in the parts of the brain associated with PD and with ET. To determine the compensatory and/or degenerative anatomical changes in the brains of PD and ET patients, the present study tested, via two voxel-based morphometry (VBM) approaches (Basic vs. DARTEL VBM processing), the anatomical brain images of 10 PD and 10 ET patients, as well as of 13 age-matched normal controls, obtained through a 3T magnetic resonance scanner. These findings indicate that PD and ET caused specific patterns of brain volume alterations in the brains examined. In addition, our observations also revealed compensatory effects, or self-reorganization, occurring in the thalamus and the middle temporal gyrus in the PD and ET patients, due perhaps in part to the enhanced thalamocortical sensorimotor interaction and the head-eye position readjustment, respectively, in these PD and ET patients. Such a distinction may lend itself to use as a biomarker for differentiating between these two diseases.
Ferromagnetic resonance properties of Fe81-xNixGa19/Si(1 0 0) and Fe81-yNiyGa19/glass films
(2013-06-15)
Liu, Chi-Ching
;
Jen, Shien-Uang
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Juang, Jenh-Yih
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Lo, Chi-Kuen
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電子物理學系
Two series of Fe81 xNixGa19/Si(100) and Fe81 yNiyGa19/glass films, where x or y = 0-26, were made by the magnetron sputtering method. The film thickness (t(f)) was fixed at 100 nm. We have performed three kinds of experiments on these films: (i) the saturation magnetostriction (lambda(S)) measurement; (ii) the easy-axis and hard-axis magnetic hysteresis loop measurements; and (iii) the ferromagnetic resonance (FMR) experiment to find the resonance field (H-R) with an X-band cavity tuned at f(R) = 9.6 GHz. The natural resonance frequency, f(FMR), of the Kittel mode at zero external field (H = 0) is defined as f(FMR) (sic) nu[H(K)4-pi M-S](1/2), where gamma = 2 pi nu is the gyromagnetic ratio, H-K and 4 pi M-S are the uniaxial anisotropy field and saturation magnetization, and H-K << 4 pi M-S. The Gilbert damping constant, alpha, is calculated from the formula, alpha = [nu(Delta H)(S)]/(2f(R)), where (Delta H)(exp) = (Delta H)(S) + (Delta H)(A), (Delta H)(exp) is the half-width of the absorption peak around the resonance field H-R, (Delta H)(S) is the symmetric part of (Delta H)(exp), and (Delta H)(A) is the asymmetric part. The degree of asymmetry, (Delta H)(A)/(Delta H)(exp), is associated with the structural and/or magnetic inhomogeneities in the film. The main findings of this study are as follows: (A) f(FMR) tends to decrease, as x or y increases; (B) alpha decreases from 0.052 to 0.020 and then increases from 0.020 to 0.050, as x increases, and a decreases from 0.060 to 0.013 in general, as y increases; and (C) lambda(S) reaches a local maximum when x = 22. We conclude that the Fe59Ni22Ga19/glass film should be the most suitable for application in magneto-electric microwave devices. (C) 2013 Elsevier B.V. All rights reserved.
Computational Investigation of the Adsorption and Reactions of SiHx (x=0-4) on TiO2 Anatase (101) and Rutile (110) Surfaces
(2013-06-15)
Huang, Wen-Fei
;
Chen, Hsin-Tsung
;
Lin, M. C.
;
應用化學系
;
應用化學系分子科學碩博班
The adsorption and reactions of the SiHx (x = 0-4) on Titanium dioxide (TiO2) anatase (101) and rutile (110) surfaces have been studied by using periodic density functional theory in conjunction with the projected augmented wave approach. It is found that SiHx (x = 0-4) can form the monodentate, bidentate, or tridentate adsorbates, depending on the value of x. H coadsorption is found to reduce the stability of SiHx adsorption. Hydrogen migration on the TiO2 surfaces is also discussed for elucidation of the SiHx decomposition mechanism. Comparing adsorption energies, energy barriers, and potential energy profiles on the two TiO2 surfaces, the SiHx decomposition can occur more readily on the rutile (110) surface than on the anatase (101) surface. The results may be used for kinetic simulation of Si thin-film deposition and quantum dot preparation on titania by chemical vapor deposition (CVD), plasma enhanced CVD, or catalytically enhanced CVD. (C) 2013 Wiley Periodicals, Inc.
Switchable tunneling mode for cylindrical photonic quantum well consisting of photonic crystals containing liquid crystal
(2013-06-15)
Hu, C. A.
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Yang, S. L.
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Yang, T. J.
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電子物理學系
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Department of Electrophysics
We propose a cylindrical photonic quantum well made of photonic crystals containing liquid crystals, the properties of which are theoretically calculated and investigated by the transfer matrix method in the cylindrical symmetry system. Liquid crystals are introduced into the photonic quantum well structure as tunable defect layers. When the liquid crystals are pseudo-isotropic state and the azimuthal mode order of incident waves are m=0, there were two pass-bands around certain wavelength. When the liquid crystals are homeotropic state, the reflectance of pass-band at shorter wavelength decreases from 0.75 to 0.05 in the TM mode, but the reflectance does not change in the TE mode. When mode order m=1 and the liquid crystals are pseudo-isotropic state, the reflectance of defect mode stayed the same as m=0. However, the result is reversed while the phase of liquid crystals change from pseudo-isotropic to homeotropic state. The reflectance is the same as in the TM mode, but that in the TE mode decreases substantially from 0.75 to 0.05. The application of our structure to switching device is highly potential. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Performance of Long-Reach Passive Access Networks Using Injection-Locked Fabry-Perot Laser Diodes With Finite Front-Facet Reflectivities
(2013-06-15)
Yeh, Chien-Hung
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Chow, Chi-Wai
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Wu, Yu-Fu
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Huang, Sung-Ping
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Liu, Yen-Liang
In this study, we use the injection-locked Fabry-Perot laser diodes (FP-LDs) with front-facet reflectivities of 10% and 35% respectively, as colorless optical networking unit (ONU) in long-reach passive optical networks (LR-PONs). Here, the injection-locked FP-LD is directly modulated at 2.5 Gbit/s on-off keying (OOK) and 10 Gbit/s orthogonal-frequency-division-multiplexing (OFDM) modulations for upstream traffic transmission over 60 km of single-mode fiber (SMF). Different operating parameters for the injection-locked FP-LD to achieve higher data rate transmission are reported.
Wavelength Tuning by Bending a Flexible Photonic Crystal Laser
(2013-06-15)
Hsu, Kung-Shu
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Chiu, Tzu-Ting
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Lee, Po-Tsung
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Shih, Min-Hsiung
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光電工程學系
This study demonstrated mechanical wavelength fine-tuning of a flexible photonic crystal (PhC) laser. A triangular PhC structure was fabricated in an InGaAsP layer on top of a polydimethylsiloxane substrate. Experiments showed two lasing modes at symmetry points K and M in the first PhC band. The laser structure was bent along the Gamma - M direction and the lasing wavelength was fine-tuned by varying the bending radius. The lasing wavelength shift is attributed to PhC lattice distortion and its tuning behavior corresponds with the simulation results. This ultra-small, wavelength-tunable laser could function as a unique light source for integrated optoelectronic circuits.
Ab Initio Chemical Kinetics for Reactions of H Atoms with SiHx (x=1-3) Radicals and Related Unimolecular Decomposition Processes
(2013-06-15)
Raghunath, Putikam
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Lee, Yun-Min
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Wu, Shang-Ying
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Wu, Jong-Shinn
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Lin, Ming-Chang
Hydrogen atoms and SiHx (x = 1-3) radicals coexist during the chemical vapor deposition (CVD) of hydrogenated amorphous silicon (a-Si: H) thin films for Si-solar cell fabrication, a technology necessitated recently by the need for energy and material conservation. The kinetics and mechanisms for H-atom reactions with SiHx radicals and the thermal decomposition of their intermediates have been investigated by using a high high-level ab initio molecular-orbital CCSD (Coupled Cluster with Single and Double)(T)/CBS (complete basis set extrapolation) method. These reactions occurring primarily by association producing excited intermediates, (SiH2)-Si-1, (SiH2)-Si-3, SiH3, and SiH4, with no intrinsic barriers were computed to have 75.6, 55.0, 68.5, and 90.2 kcal/mol association energies for x = 1-3, respectively, based on the computed heats of formation of these radicals. The excited intermediates can further fragment by H-2 elimination with 62.5, 44.3, 47.5, and 56.7 kcal/mol barriers giving Si-1, Si-3, SiH, and (SiH2)-Si-1 from the above respective intermediates. The predicted heats of reaction and enthalpies of formation of the radicals at 0 K, including the latter evaluated by the isodesmic reactions, SiHx + CH4 SiH4 + CHx, are in good agreement with available experimental data within reported errors. Furthermore, the rate constants for the forward and unimolecular reactions have been predicted with tunneling corrections using transition state theory (for direct abstraction) and variational Rice-Ramsperger-Kassel-Marcus theory (for association/decomposition) by solving the master equation covering the P, T-conditions commonly employed used in industrial CVD processes. The predicted results compare well experimental and/or computational data available in the literature. (C) 2013 Wiley Periodicals, Inc.
Enhanced Luminous Efficiency of WLEDs Using a Dual-Layer Structure of the Remote Phosphor Package
(2013-06-15)
Chen, Kuo-Ju
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Chen, Hsin-Chu
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Shih, Min-Hsiung
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Wang, Chao-Hsun
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Tsai, Hsin-Han
This study demonstrates how the insertion of a thin silicone layer into a dual-layer remote phosphor structure enhances light extraction in white light-emitting diodes (WLEDs). In the experiment, a dual-layer phosphor structure yielded a higher intensity of blue and yellow components than a conventional structure. Moreover, the lumen flux was 5% higher than a conventional remote phosphor package at the same correlated color temperature (CCT). Using a TFCalc32 simulation, the electric field intensity was calculated for different thicknesses of the dual-layer remote phosphor structures, and the enhanced use of blue rays was verified. Additionally, the dual-layer structure reduces chromaticity deviations as the driving current increases.
PQ:DMNA/PMMA photopolymer having amazing volume holographic recording at wavelength of insignificant absorption
(2013-06-15)
Chen, Yu-Fang
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Lin, June-Hua
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Lin, Shiuan Huei
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Hsu, Ken Y.
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Whang, Wha-Tzong
N, N-dimethyl-4-nitroaniline doping enables red-light holographic recording that was originally insensitive in thick phenanthrenequinone/poly(methyl methacrylate)photopolymer to have reasonable sensitivity. A volume hologram was recorded by a 647 nm laser with maximum diffraction efficiency of about 43% in a 2-mm-thick sample. A Bragg selectivity curve and an image hologram reconstruction are also demonstrated. These experimental results support recording material for volume holographic applications in an extended red spectral range. (c) 2013 Optical Society of America
珍貴文化資產　百年鐵道
(2013-06-16)
林慰
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Department of Communication and Technology
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傳播與科技學系
鐵道與國人的生活關係相當密切，台灣累積長達1世紀的鐵道文化有著豐富的內涵，從近年流行的鐵道旅行，收集車站戳章、票卷，以及鐵道攝影等活動，可看出鐵道文化不僅令人喜愛，更是人們的共同記憶。
兒童健康飲食　自主管理
(2013-06-16)
白婞嫈
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Department of Communication and Technology
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傳播與科技學系
「哈啾！」許多人對於這個詞都不陌生，甚至到了夏秋季節交替的時候，更是每天都能聽到。是什麼讓孩子在免疫系統的反應上變得較為敏感，或是缺乏抵抗力而生病呢？小孩的飲食習慣又該怎麼改變？
Clustering documents with labeled and unlabeled documents using fuzzy semi-Kmeans
(2013-06-16)
Liu, Chien-Liang
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Chang, Tao-Hsing
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Li, Hsuan-Hsun
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資訊工程學系
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Department of Computer Science
While focusing on document clustering, this work presents a fuzzy semi-supervised clustering algorithm called fuzzy semi-Kmeans. The fuzzy semi-Kmeans is an extension of K-means clustering model, and it is inspired by an EM algorithm and a Gaussian mixture model. Additionally, the fuzzy semi-Kmeans provides the flexibility to employ different fuzzy membership functions to measure the distance between data. This work employs Gaussian weighting function to conduct experiments, but cosine similarity function can be used as well. This work conducts experiments on three data sets and compares fuzzy semi-Kmeans with several methods. The experimental results indicate that fuzzy semi-Kmeans can generally outperform the other methods. (C) 2013 Elsevier B.V. All rights reserved.
瑜珈　教你如何放輕鬆
(2013-06-16)
蘇品勻
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Department of Communication and Technology
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傳播與科技學系
現代人工作繁忙，身心長時間處於緊繃的狀態，即使入睡也無法徹底放鬆，經年累月下來，使身體產生倦怠、精神不佳的情況，適當的運動能夠有效改善這些問題的產生，除了跑步、有氧，瑜珈更是許多現代人極佳選擇。
我的外食生活
(2013-06-16)
歐士豪
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Department of Communication and Technology
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傳播與科技學系
「老外、老外、老外，人人叫我老外！」說明台灣這幾年來經常在外面吃飯的人數越來越高。外食生活多鹹多油，飯後飲料也影響健康，為了健康著想，我開始改變我的飲食習慣。
命運的相遇　改變一生
(2013-06-16)
朱寶欣
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Department of Communication and Technology
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傳播與科技學系
在《逆轉人生》這部電影裡，一個是下層社會的小混混，一個是上層社會的有錢人，兩個完全沒有交集的人，他們都有著各自的命運。但是一次相遇，卻改變了他們的一生。
遊戲直播的影響
(2013-06-16)
高綮翊
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Department of Communication and Technology
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傳播與科技學系
遊戲直播在這幾年來愈來愈熱門，原本就建構在網路上的遊戲社群，也因直播的關係變得更加緊密，甚至發展出更多的互動。現今遊戲直播已經不再是一個媒介，而是一種休閒、一種練習，甚至是一種連結。
半導體元件及其製作方法
(2013-06-16)
張翼
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林岳欽
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張嘉華
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金海光
本發明提出一種半導體元件及其製作方法。該半導體元件包含:三五族半導體層;一氧化鋁層,形成於該三五族半導體層上;以及一鑭系氧化物層,形成於該氧化鋁層上。該製造半導體元件的方法包含:形成一氧化鋁層於三五族半導體層與一鑭系氧化物層之間,以防止該三五族半導體層與該鑭系氧化物層之間的原子擴散作用。
擴散式光學斷層掃描裝置及擴散式光學斷層掃描方法
(2013-06-16)
方偉騏
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陳殿河
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康適
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吳世揚
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鄭敬儒
一種擴散式光學斷層掃描裝置及擴散式光學斷層掃描方法，該裝置包括具有複數個光源和偵測器之感測電路以及具有控制單元、運算單元和影像重建單元之光學斷層掃描元件。首先，運算單元根據所設定之一待測物的光學參數建立該待測物的影像模型，並對該影像模型進行分解，接著，控制單元令複數個光源分別對該待測物發射光線，以接收該待測物與光線反應所產生之複數個光訊號，最後，令影像重建單元結合該複數個光訊號和該經分解的影像模型，以根據該複數個光訊號和該經分解的影像模型之結合，重建出待測物的影像。
復古流行趨勢報馬仔
(2013-06-16)
姜藍茵
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Department of Communication and Technology
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傳播與科技學系
相信有許多人對「復古」這個名詞並不陌生，而復古又分美式復古、日式復古和韓系復古，而現在在台灣流行的復古風是哪種呢？透過和衣服店業者、專櫃鞋店店員以及兩位復古愛好者的訪談，就能明白復古萬年不敗的魅力！