Browsing by Issue Date, starting with "2011-10-24"

Now showing 1 - 20 of 40059

Hole transport improvement in InGaN/GaN light-emitting diodes by graded-composition multiple quantum barriers
(2011-10-24)
Wang, C. H.
;
Chang, S. P.
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Ku, P. H.
;
Li, J. C.
;
Lan, Y. P.
Graded-composition multiple quantum barriers (GQB) were designed and incorporated in c-plane InGaN/GaN light-emitting diodes (LEDs) grown on c-plane sapphire substrate to improve hole transport and efficiency droop. The simulation of GQB LED design predicts enhancement of the hole transport in the active region at both low and high current densities. The fabricated LED with GQB structure exhibits lower series resistance and substantially reduced droop behavior of only 6% in comparison with 34% for conventional LED, supporting the improvement of hole transport in our design. (C) 2011 American Institute of Physics. [doi:10.1063/1.3655903]
Effect of graded-temperature arsenic prelayer on quality of GaAs on Ge/Si substrates by metalorganic vapor phase epitaxy
(2011-10-24)
Yu, H. W.
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Chang, E. Y.
;
Yamamoto, Y.
;
Tillack, B.
;
Wang, W. C.
The growth of GaAs epitaxy on Ge/Si substrates with an arsenic prelayer grown with graded temperature ramped from 300 to 420 degrees C is investigated. It is demonstrated that the graded-temperature arsenic prelayer grown on a Ge/Si substrate annealed at 650 degrees C not only improves the surface morphology (roughness: 1.1 nm) but also reduces the anti-phase domains' (APDs) density in GaAs epitaxy (dislocation density: similar to 2 x 10(7) cm(-2)). Moreover, the unwanted interdiffusion between Ge and GaAs epitaxy is suppressed by using the graded-temperature arsenic prelayer due to the low energy of the Ge-As bond and the use of a low V/III ratio of 20. (C) 2011 American Institute of Physics. [doi:10.1063/1.3656737]
Full frequency-domain approach to reciprocal microlasers and nanolasers-perspective from Lorentz reciprocity
(2011-10-24)
Chang, Shu-Wei
;
光電工程學系
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Department of Photonics
We develop a frequency-domain formulation in the form of generalized eigenvalue problems for reciprocal microlasers and nanolasers. While the goal is to explore the resonance properties of dispersive cavities, the starting point of our approach is the mode expansion of arbitrary current sources inside the active regions of lasers. Due to the Lorentz reciprocity, a mode orthogonality relation is present and serves as the basis to distinguish various cavity modes. This scheme can also incorporate the asymmetric Fano lineshape into the emission spectra of cavities. We show how to obtain the important parameters of laser cavities based on this formulation. The proposed approach could be an alternative to other computation schemes such as the finite-difference-time-domain method for reciprocal cavities. (C) 2011 Optical Society of America
Single frequency 1070 nm Nd:GdVO4 laser using a volume Bragg grating
(2011-10-24)
Shie, Nang-Chian
;
Hsieh, Wen-Feng
;
Shy, Jow-Tsong
;
光電工程學系
;
光電工程研究所
We demonstrate a single frequency diode-pumped Nd:GdVO4 laser at 1070 nm using a volume Bragg grating as the output coupler of a short plano-concave cavity. The TEM00 output had a maximum power of 300 mW and a linewidth less than 23 MHz. The beam propagation parameter M-2 and the divergence angle at 200 mW were 1.2 and 0.37 degrees, respectively. The single frequency tuning range was 5.1 GHz at 100 mW. Upon locking the laser frequency to a confocal reference cavity, a relative stability of 7.58 kHz was achieved. If frequency doubled, such as using a periodically-poled lithium niobate (PPLN) crystal, this laser offers an excellent light source for parity non-conservation experiments of atomic thallium.
Single frequency 1070 nm Nd:GdVO(4) laser using a volume Bragg grating
(2011-10-24)
Shie, Nang-Chian
;
Hsieh, Wen-Feng
;
Shy, Jow-Tsong
;
光電工程學系
;
Department of Photonics
We demonstrate a single frequency diode-pumped Nd:GdVO(4) laser at 1070 nm using a volume Bragg grating as the output coupler of a short plano-concave cavity. The TEM(00) output had a maximum power of 300 mW and a linewidth less than 23 MHz. The beam propagation parameter M(2) and the divergence angle at 200 mW were 1.2 and 0.37 degrees, respectively. The single frequency tuning range was 5.1 GHz at 100 mW. Upon locking the laser frequency to a confocal reference cavity, a relative stability of 7.58 kHz was achieved. If frequency doubled, such as using a periodically-poled lithium niobate (PPLN) crystal, this laser offers an excellent light source for parity non-conservation experiments of atomic thallium.
New one-flavor hybrid Monte Carlo simulation method for lattice fermions with gamma(5) hermiticity
(2011-10-25)
Ogawa, Kenji
;
物理研究所
;
Institute of Physics
We propose a new method for Hybrid Monte Carlo (HMC) simulations with odd numbers of dynamical fermions on the lattice. It employs a different approach from polynomial or rational HMC. In this method, gamma(5) hermiticity of the lattice Dirac operators is crucial and it can be applied to Wilson, domain-wall, and overlap fermions. We compare HMC simulations with two degenerate flavors and (1 + 1) degenerate flavors using optimal domain-wall fermions. The ratio of the efficiency, (number of accepted trajectories)/(simulation time), is about 3 : 2. The relation between pseudofermion action of chirally symmetric lattice fermions in four-dimensional (overlap) and five-dimensional (domain-wall) representation are also analyzed. (C) 2011 Elsevier B.V. All rights reserved.
Effects of CF4 plasma treatment on the moisture uptake, diffusion, and WVTR of poly(ethylene terephthalate) flexible films
(2011-10-25)
Wang, Chih
;
Lai, Po-Cheng
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Syu, Shu Hao
;
Leu, Jihperng
;
材料科學與工程學系
We studied the effects of CF4 plasma surface treatment on moisture uptake, diffusion, and the water-vapor-transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF4 plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF4 plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m(2)/day, while a significant reduction (84%) of WVTR to 0.43 g/m(2)/day, is achieved for CF4 plasma-treated PET film (60 W. 15 min), which alters the surface hydrophobicity (similar to 107 degrees) and simultaneously builds a denser, fluorinated top-layer (47 nm). The surface fluorinated layer has a diffusivity of to 8.7 x 10(-12) m(2)/s and a WVTR of similar to 1.0 x 10(-4) g/m(2)/day based on a series resistance model. (C) 2011 Elsevier B.V. All rights reserved.
Effects of CF(4) plasma treatment on the moisture uptake, diffusion, and WVTR of poly(ethylene terephthalate) flexible films
(2011-10-25)
Wang, Chih
;
Lai, Po-Cheng
;
Syu, Shu Hao
;
Leu, Jihperng
;
材料科學與工程學系
We studied the effects of CF(4) plasma surface treatment on moisture uptake, diffusion, and the water-vapor-transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF(4) plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF(4) plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m(2)/day, while a significant reduction (84%) of WVTR to 0.43 g/m(2)/day, is achieved for CF(4) plasma-treated PET film (60 W. 15 min), which alters the surface hydrophobicity (similar to 107 degrees) and simultaneously builds a denser, fluorinated top-layer (47 nm). The surface fluorinated layer has a diffusivity of to 8.7 x 10(-12) m(2)/s and a WVTR of similar to 1.0 x 10(-4) g/m(2)/day based on a series resistance model. (C) 2011 Elsevier B.V. All rights reserved.
人生如戲：高夫曼《日常生活中的自我表演》
(2011-10-26)
曾凡慈
;
開放教育推動中心
;
Open Education Office
課程首頁本課程是由交通大學新文藝復興閱讀計畫提供。 96 年 8 月當各大學紛紛摩拳擦掌準備迎接新生的同時，交通大學校長吳重雨則因為一則來自於七月份泰晤士報，有關於英國首相布朗公布其夏日讀書清單的新聞中，看到了他對知識的尊重。在這同時，吳重雨校長也思考著，要如何為學生準備追求知識的環境和激發他們對知識的尊重與喜愛。台積電張忠謀董事長曾陳述他 18 歲進入哈佛那一年，博覽文史哲理工經典群籍，至此奠定了他求知的基礎，並借海明威名言，將其改為「哈佛這一年為人生可帶走的盛宴。」吳重雨校長以張董事長的學習為借鏡，認為學生固然能藉由自我閱讀的方式學習到豐沛的知識，但透過名人、大師親臨現場地介紹經典書籍，更能加深學子們對於書籍的認識與興趣，這也是「新文藝復興閱讀計劃」 ( 以下簡稱 : 「經典名著選讀」 ) 活動展開籌劃的緣由。於是，吳重雨校長便積極敦請「交大通識教育委員會」，接手籌備本計劃的相關活動，而該中心也成為實際施行本計畫的策動、開課以及認證單位。至此，期許交大學子藉由閱讀、聽講來提昇人文素養、開拓視野的「新文藝復興閱讀計劃」，就此展開。
Effect of Mn substitution on electronic structure of Ca9Y(PO4)(7):Eu2+, Mn2+ phosphor determined by X-ray absorption spectroscopy
(2011-10-27)
Lu, Y. R.
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Huang, C. H.
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Chen, T. M.
;
Lin, J. H.
;
Ma, Y. R.
The single-composition Ca9Y(PO4)(7):Eu2+, Mn2+ phosphors were synthesized by a solid-state reaction. The luminescent properties and electronic structures were investigated by photoluminescence (PL) and X-ray absorption near-edge structure (XANES). The PL demonstrated energy transfer and a red-shift as the Mn doping level was increased. The energy transfer is ascribed to charge transfer between Eu and Mn. The change of the PL intensity is caused by the increased O 2p-Mn 3d hybridization. The narrowing of the band gap, which finding is supported by the red-shift, is responsible for the formation of the Mn-related states close to the conduction band minimum. (C) 2011 Elsevier B.V. All rights reserved.
MEMS GYROSCOPE
(2011-10-27)
CHEN Tsung-Lin
;
Chi Chien-Yu
;
Lee Chia-Wei
An MEMS gyroscope is disclosed, capable of computing the rotating angle of a DUT being attached thereto without the need to execute an off-line calibration process, of precluding the execution of an integration process, and of executing an on-line compensation process for the error introduced by the sensing circuit defect and by the mechanical structure defect of its gyroscope module. The disclosed MEMS gyroscope comprises: a gyroscope module, a sensing module coupled with the gyroscope module, and a control module couple with the gyroscope module and the sensing module, respectively. The control module receives the system dynamic of the gyroscope module sensed by the sensing module, and applies a gyroscope control method for controlling the gyroscope module and computing the rotating angle of the DUT. Moreover, the control module outputs a control signal including two extra frequency signals, to the gyroscope module, for driving the gyroscope module into operation.
A fuzzy pattern-based filtering algorithm for botnet detection
(2011-10-27)
Wang, Kuochen
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Huang, Chun-Ying
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Lin, Shang-Jyh
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Lin, Ying-Dar
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資訊工程學系
Botnet has become a popular technique for deploying Internet crimes. Although signature-based bot detection techniques are accurate, they could be useless when bot variants are encountered. Therefore, behavior-based detection techniques become attractive due to their ability to detect bot variants and even unknown bots. In this paper, we propose a behavior-based botnet detection system based on fuzzy pattern recognition techniques. We intend to identify hot-relevant domain names and IP addresses by inspecting network traces. If domain names and IP addresses used by botnets can be identified, the information can be further used to prevent protected hosts from becoming one member of a botnet. To work with fuzzy pattern recognition techniques, we design several membership functions based on frequently observed bots' behavior including: (1) generate failed DNS queries; (2) have similar DNS query intervals; (3) generate failed network connections; and (4) have similar payload sizes for network connections. Membership functions can be easily altered, removed, or added to enhance the capability of the proposed system. In addition, to improve the overall system performance, we develop a traffic reduction algorithm to reduce the amount of network traffic required to be inspected by the proposed system. Performance evaluation results based on real traces show that the proposed system can reduce more than 70% input raw packet traces and achieve a high detection rate (about 95%) and a low false positive rates (0-3.08%). Furthermore, the proposed FPRF algorithm is resource-efficient and can identify inactive botnets to indicate potential vulnerable hosts. (C) 2011 Elsevier B.V. All rights reserved.
Environment-Dependent Ultrafast Photoisomerization Dynamics in Azo Dye
(2011-10-27)
Hsu, Chun-Chih
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Wang, Yu-Ting
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Yabushita, Atsushi
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Luo, Chih-Wei
;
Hsiao, Yi-Nan
Azoaromatic dyes have been extensively investigated over the past decade due to their potential use in a variety of optical devices that exploit their ultrafast photoisomerization processes. Among the azoaromatic dyes, Disperse Red 19 is a commercially available azobenzene nonlinear optical chromophore with a relatively high ground-state dipole moment. In the present study, we used ultrafast time-resolved spectroscopy to clarify the dynamics of a push-pull substituted azobenzene dye. Solution and film samples exhibited different ultrafast dynamics, indicating that the molecular environment affects the photoisomerization dynamics of the dye.
APPARATUS FOR IDENTIFYING FALLS AND ACTIVITIES OF DAILY LIVING
(2011-10-27)
Yang Bing-Shiang
;
Wang Chih-Chung
;
Liao Sain-Ting
The present invention provides and apparatus for distinguishing falls from activities of daily living (ADLs). First, the human movements and muscle activities would be obtained by an electromyography measuring unit and/or an inertia measuring unit to record ADLs, and falls would be distinguished from ADLs to trigger the protecting devices in time to prevent or decrease injury. In addition, the apparatus would be preset for different operational conditions to adapt different users by a setting unit to increase accuracy. Finally, the moving distance and the direction of the user would be obtained by the electromyography measuring unit and/or the inertia measuring unit to obtain the location thereof in an interior space.
Effect of Mn substitution on electronic structure of Ca(9)Y(PO(4))(7):Eu(2+), Mn(2+) phosphor determined by X-ray absorption spectroscopy
(2011-10-27)
Lu, Y. R.
;
Huang, C. H.
;
Chen, T. M.
;
Lin, J. H.
;
Ma, Y. R.
The single-composition Ca(9)Y(PO(4))(7):Eu(2+), Mn(2+) phosphors were synthesized by a solid-state reaction. The luminescent properties and electronic structures were investigated by photoluminescence (PL) and X-ray absorption near-edge structure (XANES). The PL demonstrated energy transfer and a red-shift as the Mn doping level was increased. The energy transfer is ascribed to charge transfer between Eu and Mn. The change of the PL intensity is caused by the increased O 2p-Mn 3d hybridization. The narrowing of the band gap, which finding is supported by the red-shift, is responsible for the formation of the Mn-related states close to the conduction band minimum. (C) 2011 Elsevier B.V. All rights reserved.
13 Gbit/s WDM-OFDM PON using RSOA-based colourless ONU with seeding light source in local exchange
(2011-10-27)
Chow, C. W.
;
Yeh, C. H.
;
Wu, Y. F.
;
Chen, H. Y.
;
Lin, Y. H.
Optical-carrier-distribution using reflective-semiconductor-optical-amplifier (RSOA)-based colorless optical-networking-unit (ONU) is a promising candidate for the wavelength-division-multiplexed passive-optical-network (WDM-PON). However, commercial available RSOA has a typical modulation-bandwidth of similar to 1 GHz, which is not enough for the future bandwidth demand. Here we demonstrate a WDM-PON using 1 GHz bandwidth RSOA-based ONU, which can be operated up to 13 Gbit/s. Experimental results show that 20 km singlemode-fibre transmission of the 13 Gbit/s orthogonal-frequency-division-multiplexed (OFDM) signal can be achieved with bit-error rate lower than the forward error correction threshold.
低密度パリティ検査（ＬＤＰＣ）デコーダに応用する演算回路
(2011-10-28)
陸志豪
;
廖▲彦▼欽
;
李鎮宜
;
張錫嘉
;
許雅三
Using simplified drum-buffer-rope for re-entrant flow shop scheduling in a random environment
(2011-10-28)
Chang, Yung-Chia
;
Huang, Wen-Tso
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
The traditional simplified drum buffer rope (SDBR) does not consider the application of re-entrant flow shop (RFS) in a random environment which might involve variable processing times and machine breakdowns. This paper proposed a weighted layer production buffer and weighted production buffer to monitor the status of the buffer deviation when applying SDBR in a RFS with non-deterministic parameters. The buffer status deviation used the overall urgency and actual urgency to estimate the influence of overall accumulated machine downtime and the influence of actual machine downtime of capacity-constrained-resource (CCR) at different layers. A dispatching rule, called SDBR_D(Reentry), was applied to decide the priority of all work orders by the buffer status deviation of each CCR machine with the consideration of the re-entry feature. A simulated RFS was designed and four different methods (including ours) were applied in order to demonstrate the effectiveness of our approach. The experimental results show that when compared to six performance indexes related to the due date, our approach has better performance than the other three methods when the product mix with a large proportion of multi-reentrant orders and when the CCR utilization increases from 60 to 90%.
造窯生勢　此造窯非彼造謠
(2011-10-30)
林筱娟
;
Department of Communication and Technology
;
傳播與科技學系
全國第二屆蓋窯大賽「造窯生勢」，10月21日起在亞太創意技術學院舉行為期三天的賽事，十組參賽隊伍必須在55個小時內完成蓋窯、起火燒製陶器及封窯等工作，是一場技術與體力的馬拉松式競賽。
衝線之前　都還沒結束
(2011-10-30)
陳建安
;
Department of Communication and Technology
;
傳播與科技學系
一個國立大學出來的學生，追求夢想勇往直前，不畏大環境的挑戰和艱苦，執意要成為一個車手，這其中的點滴辛酸，值得我們一探究竟。