Browsing by Issue Date, starting with "2007-11-07"

Now showing 1 - 20 of 58709

Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands
(2007-11-07)
Chiu, C. H.
;
Lu, T. C.
;
Huang, H. W.
;
Lai, C. F.
;
Kao, C. C.
We report the fabrication of InGaN/GaN nanorod light-emitting diodes (LEDs) using inductively coupled plasma reactive-ion etching (ICP-RIE) and a photo-enhanced chemical (PEC) wet oxidation process via self-assembled Ni nanomasks. An enhancement by a factor of six times in photoluminescence (PL) intensities of nanorods made with the PEC process was achieved in comparison to that of the as-grown structure. The peak wavelength observed from PL measurement showed a blue shift of 3.8 nm for the nanorods made without the PEC oxidation process and 8.6 nm for the nanorods made with the PEC oxidation process from that of the as-grown LED sample. In addition, we have demonstrated electrically pumped nanorod LEDs with the electroluminescence spectrum showing more efficiency and a 10.5 nm blue-shifted peak with respect to the as-grown LED sample.
Capacity-based compressed mode control method for inter-system handover in universal mobile telecommunication system
(2007-11-08)
Huang, Ching Yao
;
Chang, Cheng Ta
;
Ho, Chieh Yuan
The Inter-System handover is one of the key features in the third generation cellular systems. The compressed mode, with variable transmission gaps and power levels, is standardized to support the inter-frequency system handover. To minimize the use of system resources while maintaining the border-cell handover quality, a capacity-based compressed mode control method of the present invention is proposed. Considering the tradeoff between the capacity and the communication quality, the control method can adaptively manage the compressed mode operation based on the potential impacts on the capacity and the effectiveness of the compressed mode measurement. The present invention will improve the effectiveness and performance of the compressed mode operation.
Method for parameter identification and parameter optimization of microspeakers
(2007-11-08)
Bai, Mingsian R.
;
Chen, Rong Liang
The present invention discloses a method for parameter identification and parameter optimization of microspeakers. Measurement procedures for identifying electromechanical constants of microspeaker and a GUI are developed to facilitate estimation of electroacoustic parameters of the microspeaker under test. In light of the thus identified microspeaker parameters, a parameter optimization procedure is carried out to obtain the design that attains the best acoustic performance with minimum harmonic distortion.
Dual bandpass filter having serial configuration of coupled-line filters
(2007-11-08)
Chung, Shyh-Jong
;
Lin, Ke-Chiang
;
Chang, Chun-Fu
Two second-order bandpass filter are connected serially to obtain a dual bandpass filter. One is inductive and the other is capacitive. One has a low passband and the other has a high passband. Between them, a finite transmission zero is formed to suppress noise. The present invention achieves a passband as wide as 1 gigahertz so that it can be applied to a wireless local network, communication equipments and electronic devices.
Virtual machine support for zero-loss Internet service recovery and upgrade
(2007-11-10)
Chang, Da-Wei
;
Hsieh, Cheng-En
;
Chen, Yan-Pai
;
Chiu, Kwo-Cheng
;
資訊工程學系
Software is critical for Internet service availability since an Internet service may become unavailable due to software faults or software maintenance. In this paper, we propose a framework to allow zeroloss recovery and online maintenance for Internet services. The framework is based on the virtual machine (VM) technology and a connection migration technique called FT-TCP. It can recover transient application/operating system faults and it allows fault recovery and online maintenance on a single host. The framework substantially enhances FT-TCP so that it can be run efficiently in the VM environment. Specifically, we propose techniques to reduce the inter-VM switches and communication. Moreover, we propose service-specific optimizations to reduce the recovery time of FT-TCP. Finally, the framework provides an interface for the service designers to implement more service-specific optimizations. The framework was implemented by modifying an open source VM monitor, Xen, and the Linux kernel running on top of Xen. The effectiveness and efficiency of the framework were evaluated by running two Internet services, WWW proxy and FTP, on the proposed framework and measuring the impact on their performance. According to the experimental results, our approach causes only slight performance overhead (i.e. less than 4%) and memory overhead (i.e. less than 750 KB) for both the services. Copyright (C) 2007 John Wiley & Sons, Ltd.
Polycrystalline silicon thin-film transistors with location-controlled crystal grains fabricated by excimer laser crystallization
(2007-11-12)
Tsai, Chun-Chien
;
Lee, Yao-Jen
;
Chiang, Ko-Yu
;
Wang, Jyh-Liang
;
Lee, I-Che
In this paper, location-controlled silicon crystal grains are fabricated by the excimer laser crystallization method which employs amorphous silicon spacer structure and prepatterned thin films. The amorphous silicon spacer in nanometer-sized width formed using spacer technology is served as seed crystal to artificially control superlateral growth phenomenon during excimer laser irradiation. An array of 1.8-mu m-sized disklike silicon grains is formed, and the n-channel thin-film transistors whose channels located inside the artificially-controlled crystal grains exhibit higher performance of field-effect-mobility reaching 308 cm(2)/V s as compared with the conventional ones. This position-manipulated silicon grains are essential to high-performance and good uniformity devices. (c) 2007 American Institute of Physics.
Water passivation effect on polycrystalline silicon nanowires
(2007-11-12)
Lin, Horng-Chih
;
Su, Chun-Jung
;
Hsiao, Cheng-Yun
;
Yang, Yuh-Shyong
;
Huang, Tiao-Yuan
Defects present in the grain boundaries of polycrystalline materials are known to impede carrier transport inside the materials, and the electronic device performance having such materials as active channels will be adversely affected. In this work, dramatic improvement in device performance was observed as field-effect transistors with polycrystalline silicon nanowire (poly-SiNW) channels were exposed to a wet environment. Passivation of defects in the poly-SiNW by H+ and/or OH- contained in the aqueous solution is proposed to explain the phenomenon. (c) 2007 American Institute of Physics.
Direct visualization of triplex DNA molecular dynamics by fluorescence resonance energy transfer and atomic force microscopy measurements
(2007-11-12)
Chang, Chia-Ching
;
Lin, Po-Yen
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Chen, Yen-Fu
;
Chang, Chia-Seng
;
Kan, Lou-Sing
We have detected the dynamics of 17-mer DNA triplex dissociation mechanism at the molecular level. Fluorescence resonance energy transfer (FRET) was used as an indicator of intermolecular interaction in nanometer range, whereas atomic force microscopy (AFM) was employed to address single molecule with sub-angstrom precision. The maximum rupture force of DNA triplex was found at pH 4.65, consistent with macroscopic observations. These results indicated that the FRET together with an AFM detection system could be used to reveal the DNA triplex interaction in nanometer scale unambiguously. (c) 2007 American Institute of Physics.
Linear relations and their breakdown in high energy massive string scatterings in compact spaces
(2007-11-12)
Lee, Jen-Chi
;
Yang, Yi
;
電子物理學系
;
Department of Electrophysics
We calculate high energy massive scattering amplitudes of closed bosonic string compactified on the torus. For each fixed mass level with given quantized and winding momenta (m/R ,1/2 nR), we obtain infinite R linear relations among high energy scattering amplitudes of different string states. For some kinematic regimes, we discover that linear relations with N-R = N-L break down and, simultaneously, the amplitudes enhance to power-law behavior instead of the usual exponential fall-off behavior at high energies. It is the space-time T-duality symmetry that plays a role here. This result is consistent with the coexistence of the linear relations and the softer exponential fall-off behavior of high energy string scattering amplitudes as we pointed out previously. It is also reminiscent of our previous work on the power-law behavior of high energy string/domain-wall scatterings. (c) 2007 Elsevier B.V. All rights reserved.
Process for manufacturing self-assembled nanoparticles
(2007-11-13)
Chen
;
Wei-Kuo
;
Lee
;
Ming-Chih
;
Chou
Process for fabricating self-assembled nanoparticles on buffer layers without mask making and allowing for any degree of lattice mismatch; that is, binary, ternary or quaternary nanoparticles comprising Groups III-V, II-VI or IV-VI. The process includes a first step of applying a buffer layer, a second step of turning on the purge gas to modulate the first reactant to the lower first flow rate, then the second reactant is supplied to the buffer layer to form a metal-rich island on the buffer layer, and a third step of turning on purge gas again to modulate the first reactant to the higher second flow rate onto the buffer layer. On the metal-rich island is formed the nanoparticles of the binary, ternary or quaternary III-V, II-VI and IV-IV semiconductor material. This is then recrystallized under the first reactant flow at high temperature forming high quality nanoparticles.
Characterizing the Hsincheng active fault in northern Taiwan using airborne LiDAR data: Detailed geomorphic features and their structural implications
(2007-11-15)
Chan, Yu-Chang
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Chen, Yue-Gau
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Shih, Tian-Yuan
;
Huang, Chung
;
土木工程學系
We applied newly acquired high-resolution airborne LiDAR data to study a segment of the Hsincheng fault, a well-known active fault near a large industrial park in northern Taiwan. The Hsincheng fault has received much attention and study in the past; but high spatial resolution digital elevation models have not previously been applied to the study of the fault and its surrounding structures. We processed the acquired LiDAR data and produced I in digital elevation models (DEMs) to investigate the active fault adjacent to the densely populated and important infrastructure in Taiwan. Using the LiDAR DEMs, aerial photographs and topographic maps, we show highly detailed geomorphic characteristics around the study area of the Hsincheng fault. Three major characteristics of the study area are defined that include three very well preserved river terraces at varying levels, the fault/fold scarp of the Hsincheng fault, and meandering river systems. Using the LiDAR DEMs, we were able to detect with precision several fault/fold scarps and very gentle NE-trending folding of the river terraces. In general, the LiDAR DEMs have provided unprecedented clarity of landforms for one segment of the Hsincheng fault, which has helped the characterization of subtle but important geomorphic features. (c) 2007 Elsevier Ltd. All rights reserved.
Growth and characteristics of lead sulfide nanocrystals produced by the porous alumina membrane
(2007-11-15)
Chen, Jung-Hsuan
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Chao, Chuen-Guang
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Ou, Jong-Chyan
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Liu, Tzeng-Feng
;
材料科學與工程學系
Lead sulfide (PbS) nanocrystals were formed by using Pb nanowires reacted with hydrogen sulfide (H2S) gas. The structure and composition of the as-prepared nanocrystals were confirmed by scanning electron microscopy, X-ray diffraction, transmission electron microscope and energy dispersive X-ray spectroscopy. According to the differential scanning calorimeter analysis, the PbS nanocrystals in a cubic structure owned excellent thermal stability. Furthermore, the optical properties including photoluminescence (PL) and Raman scatting spectrum were also measured. The PL emission measurement of the PbS nanocrystal showed that there was an orange-red emission peak located around 655 nm. A significant quantum confinement effect made the energy gap of PbS produce a blue shift from 0.41 eV to 1.9 eV. (C) 2007 Elsevier B.V. All rights reserved.
Anomalous phase behavior and apparent anharmonicity of the pump-probe signal in a two-dimensional harmonic potential system
(2007-11-15)
Taneichi, T.
;
Kobayashi, T.
;
先進超快雷射研究中心
;
Adv Ultrafast Laser Ctr
Discussion on wavelength dependent "anharmonic" effects in a pump-probe signal for a system of wavepacket on one- and two-dimensional harmonic potentials was given. The Fourier power spectrum of the signal, calculated for a model composed of a three-state electronic system coupled to a set of displaced harmonic oscillators, depends on the pulse duration. Condition under which the wavepacket motion in the harmonic potential substantially deviates from that of the classical point mass is derived. The Fourier power spectrum has enhanced components with frequencies of harmonies even in a system composed of ideally harmonic potentials. Utility of the Fourier analysis of the spectrum for clarification of the squeezed molecular vibrational state is discussed. Calculated oscillatory behavior in phase of a pump-probe signal, as a function of probe frequency, was discussed in terms of a two-dimensional effect on a pump-probe signal. (C) 2007 Elsevier B.V. All rights reserved.
Chirped molecular vibration in a stilbene derivative in solution
(2007-11-15)
Colonna, Anne
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Yabushita, Atsushi
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Iwakura, Izumi
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Kobayashi, Takayoshi
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電子物理學系
The wave packet dynamics of 4-methoxy-4 '-nitrostilbene in solution was studied by femtosecond pump-probe spectroscopy. Transient changes in absorbance exhibit oscillations, which reflect vibrational motions on the ground-state potential surface. Modification of this oscillatory feature in three different solvents (benzene, methanol, and acetonitrile) can be explained in term of the strength of hydrogen bonding and the stabilization of charge-transfer state, confirmed by steady-state absorption and fluorescence spectra. (c) 2007 Elsevier B.V. All rights reserved.
串聯電感性及電容性耦合傳輸線濾波器之雙頻帶通濾波器
(2007-11-16)
鍾世忠
;
林克強
;
張鈞富
本發明為串聯電感性及電容性耦合傳輸線濾波器之雙頻帶通濾波器,本發明之雙頻帶通濾波器由低頻二階電感(電容)性帶通濾波器與二階高頻電容(電感)性帶通濾波器串接構成,高頻二階電容性帶通濾波器內傳輸線反接,使其相位與低頻二階電感性帶通濾波器之相位差180度,所以可將兩者串接,又因阻抗串接,使低頻二階電感性帶通濾波器與高頻二階電容性帶通濾波器之通帶區間產生有限傳輸零點,並可有效抑制外來之干擾訊號,而本發明之雙頻帶通濾波器之高頻通帶頻寬可達到1GHz,所以本發明之雙頻帶通濾波器之電路架構可應用於無線區域網路、電信、電機及電子相關領域上。
基於電腦視覺的智慧型夜間車輛即時偵測與辨識系統
(2007-11-16)
吳炳飛
;
陳彥霖
;
陳元馨
;
陳昭榮
本發明係關於一種夜間車輛即時偵測與辨識系統,其包含:光源物件影像切割裝置1,光源物件分類裝置2,車燈物件辨識裝置3,車輛位置判定裝置4以及車輛追蹤裝置5;在各種夜間道路照明狀態下,該系統能有效且正確地標定與辨識來車與前車之車燈,且在當時道路環境狀況下,正確地提供輔助駕駛所需解析車輛前方交通狀況之資訊。
微型揚聲器之參數鑑別及參數最佳化之方法
(2007-11-16)
白明憲
;
陳榮亮
本發明係提供一種微型揚聲器之參數鑑別及參數最佳化之方法,其係針對微型揚聲器所設計,經由機電常數的量測程序,並撰寫GUI軟體介面以求出微型揚聲器的電聲系統參數,並在計算出微型揚聲器之參數値後,以參數設計最佳化之方法,使微型揚聲器可發揮最佳聲學效果及最小諧波失真。
手指指向偵測系統及方法
(2007-11-16)
黃仲陵
;
傅智銘
;
簡敬宇
本發明係提供一種手指指向偵測系統及方法,其係以數台影像擷取裝置擷取使用者之數張手部影像,並以一處理器對擷取之數張手部影像進行影像處理求出數條手指指向線,利用座標轉換程式轉換出手指指向線於指向平面上的投影線,最後計算數條投影線之交點,即為使用者手指指向之目標點。本發明不需使用任何定位手套或標記手套即可偵測出使用者指向一平面上之任意目標點,具有高辨析度及高準確率,且可應用於簡報系統,作為取代雷射筆或滑鼠之人機介面。
泛用行動通訊系統中系統間交遞之容量為主之壓縮模式的控制方法
(2007-11-16)
黃經堯
;
張正達
;
何玠原
第三代手機系統的重要特色之一為系統間交遞,具有可變傳輸間隙及可變位準之壓縮模式,以正規化地支援系統間及頻率間之交遞,為了將系統之使用資源最小化,當須維持邊界單元的交遞品質時,可採用本發明之容量為主之壓縮模式的控制方法,而在容量與通訊品質互相牽制的考量下,本發明之控制方法在基於容量之潛在影響及壓縮模式量測之成效,可適應性地管理壓縮模式之操作,本發明可增加壓縮模式之操作的成效及表現。
一種即時階層式背景重建與前景偵測之方法
(2007-11-16)
陳祝嵩
;
陳昱廷
本發明揭露一種即時階層式背景重建與前景偵測之方法,可於視訊中進行背景重建與前景偵測,其主要特徵係在於整合了以區塊為基礎(Block-Based)之粗階(Coarse-Level)背景模型(Background Modeling)與以像素為基礎(Pixel-Based)之細階(Fine-Level)背景模型方法。首先,本方法將影像劃分成不互相重疊的影像區塊,並針對每一個區塊建立其粗階背景模型,有了此一模型便可進行快速但形狀較粗略的前景物體偵測。在有了粗略前景偵測結果後,再將此結果饋入(Feed)細階背景模型做進一步的判斷分析。其中在粗階背景重建部份係以一個新發展的區塊描述元(Descriptor)來描述區塊內含資訊的特徵,此一描述元稱為差異均値向量(Difference Mean Vector,DMV)。此外,高斯混和(Gaussian Mixture)方法被使用來對差異均値向量特徵進行粗階背景模型的建構。細階部份則可採用現行習知之以像素為基礎的背景重建方法。另外,一前饋架構(Feed-Forward Framework)亦被揭露來整合粗階背景模型與細階背景模型,其將粗階部份所辨認到的資訊饋入至細階部份,以進行粗階前景偵測結果的細緻化與細階背景模型的更新。