Browsing by Issue Date, starting with "2010-06-07"

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Transmission of 20-Gb/s OFDM signals occupying 7-GHz license-free band at 60 GHz using a RoF system employing frequency sextupling optical up-conversion
(2010-06-07)
Shih, Po-Tsung
;
Lin, Chun-Ting
;
Jiang, Wen-Jr
;
Huang, Han-Sheng
;
Chen, Jyehong
This work describes a proposed 60-GHz radio-over-fiber (RoF) system employing a frequency sextupling optical up-conversion scheme. Based on the modified single sideband modulation scheme, spectrally efficient vector signals were transmitted with no performance degradation due to dispersion-induced fading. Wavelength-division-multiplexed optical up-conversion can be realized using the proposed system. Since the required transmitter bandwidth is significantly reduced, radio-frequency components with lower bandwidth and higher reliability can be utilized. Both 13.75-Gb/s QPSK-OFDM and 20.625-Gb/s 8QAM-OFDM signals were experimentally demonstrated. After transmission over 25-km of standard single mode fiber, no significant received power penalty was observed. (C) 2010 Optical Society of America
Low efficiency droop in blue-green m-plane InGaN/GaN light emitting diodes
(2010-06-07)
Ling, Shih-Chun
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Lu, Tien-Chang
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Chang, Shih-Pang
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Chen, Jun-Rong
;
Kuo, Hao-Chung
We investigated the electroluminescence and relatively external quantum efficiency (EQE) of m-plane InGaN/GaN light emitting diodes (LEDs) emitting at 480 nm to elucidate the droop behaviors in nitride-based LEDs. With increasing the injection current density to 100 A/cm(2), the m-plane LEDs exhibit only 13% efficiency droop, whereas conventional c-plane LEDs suffer from efficiency droop at very low injection current density and the EQE of c-plane LEDs decrease to as little as 50% of its maximum value. Our simulation models show that in m-plane LEDs the absence of polarization fields manifest not only the hole distribution more uniform among the wells but also the reduction in electron overflow out of electron blocking layer. These results suggest that the nonuniform distribution of holes and electron leakage current due to strong polarization fields are responsible for the relatively significant efficiency droop of conventional c-plane LEDs. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3449557]
交大e-News第072期
(2010-06-07)
Secretariat
;
國立交通大學秘書室
Organic optoelectronic component
(2010-06-09)
Meng, Hsin-Fei
;
Horng, Sheng-Fu
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Tseng, Hsin-Rong
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Li, Guan-Cheng National Chiao Tung University
An organic optoelectronic component is provided, which includes a first electrode, an active layer formed on the first electrode, a second intermediate layer formed on the active layer, and a second electrode formed on the second intermediate layer, wherein the second intermediate layer is formed with a second mixture containing a second polymer and at least a second organic molecule. The second organic molecule is one for forming hole transferring material, electron transferring material, electron blocking material or hole blocking material. The organic optoelectronic component of the present invention is prepared by a solution process, thereby simplifying the process, improving film-formation property, and enhancing component efficiency.
Impact of electric quadrupolar coupling on the optical response of an array of nano-objects
(2010-06-09)
Lin, Chien Y.
;
Wang, Yun H.
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Huang, Jung Y.
;
Liu, Yongjun
;
Zhao, Yiping
Intra- and inter-particle coupling effects are important but have not been properly taken into account in modeling the optical response of an array of nano-objects. In this paper, we present a method to analyze the impact of electric quadrupolar coupling on the optical response of a layer of silver nanorods fabricated with oblique-angle deposition (OAD). Our technique can render the non-locally coupled nano-objects into an array of coarse-grained induced charges. The retrieved polarizability tensor of the silver nanorods exhibits non-zero off-diagonal components, revealing information about the array structure and inter-particle quadrupolar couplings. Thus, a more transparent picture of the correlation between the function and structure of an optical metamaterial can be yielded.
Synthesis for catelysis of bifunctional perovskite compound
(2010-06-10)
Wu, Pu-Wei
;
Chang, Yun-Min
This invention discloses the synthesis of a bifunctional La0.6Ca0.4Co1-xIrxO3 (x=0˜1) perovskite compound with a superb bifunctional catalytic ability for the oxygen reduction and generation in alkaline electrolytes. Synthetic routes demonstrated include solid state reaction, amorphous citrate precursor, and mechanical alloying. The interested compound demonstrates notable enhancements over commercially available La0.6Ca0.4CoO3.
Two Different Charge Transfer States of Photoexcited 9,9 '-Bianthryl in Polar and Nonpolar Solvents Characterized by Nanosecond Time-Resolved Near-IR Spectroscopy in the 4500-10 500 cm(-1) Region
(2010-06-10)
Asami, Nobuyuki
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Takaya, Tomohisa
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Yabumoto, Soshi
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Shigeto, Shinsuke
;
Hamaguchi, Hiro-o
Transient absorption spectra of 9,9'-bianthryl (BA) in heptane, in acetonitrile, and in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmimTf(2)N) are observed with a nanosecond time-resolved near-IR absorption spectrometer for the wavenumber range of 4500-10 500 cm(-1) (2200-950 nm). In nonpolar heptane solution, a broad absorption band is observed at 6700 cm(-1)(1500 urn), in addition to a strong absorption band of the locally excited (LE) state centered at 9800 cm(-1) (1020 nm). The broad band is assigned to a partial charge transfer (PCT) band. The decay time constants of the PCT band and the LE band are both (13 +/- 1) ns. The agreement of the two decay constants strongly suggests that the PCT state is in equilibrium with the LE state in heptane. In acetonitrile, an absorption band of the charge transfer (CT) state is observed at 8000 cm(-1) (1250 nm). This band decays in (41 +/- 2) ns. In bmimTf(2)N, the CT band appears at 8500 cm(-1) (1180 nm) and decays in (34 +/- 1) ns. The difference in peak position for the CT bands in acetonitrile and in bmimTf(2)N, and the PCT bands in heptane, is explained well by the model based on the charge resonance between the two equivalent electronic structures of the CT state.
ELECTROSTATIC DISCHARGE PROTECTION DEVICE AND RELATED CIRCUIT
(2010-06-10)
Ker, Ming-Dou
;
Hsiao, Yuan-Wen
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Wang, Chang-Tzu
An ESD protection device comprises a P-type substrate, a first substrate-triggered silicon controlled rectifiers (STSCR) disposed in the P-type substrate and a second STSCR disposed in the P-type substrate. The first STSCR comprises a first N-well, a first P-well, a first N+ diffusion region, a first P+ diffusion region, and a first trigger node. The second STSCR comprises a second N-well electrically connected to the first N-well, a second P-well electrically connected to the first P-well, a second N+ diffusion region electrically connected to the first P+ diffusion region, a second P+ diffusion region electrically connected to the first N+ diffusion region, and a second trigger node. A layout area of an integrated circuit and a pin-to-pin ESD current path can be reduced.
ORGANIC OPTOELECTRONIC COMPONENT
(2010-06-10)
Meng, Hsin-Fei
;
Horng, Sheng-Fu
;
Tseng, Hsin-Rong
;
Li, Guan-Cheng
An organic optoelectronic component is provided, which includes a first electrode, an active layer formed on the first electrode, a second intermediate layer formed on the active layer, and a second electrode formed on the second intermediate layer, wherein the second intermediate layer is formed with a second mixture containing a second polymer and at least a second organic molecule. The second organic molecule is one for forming hole transferring material, electron transferring material, electron blocking material or hole blocking material. The organic optoelectronic component of the present invention is prepared by a solution process, thereby simplifying the process, improving film-formation property, and enhancing component efficiency.
用於ＩＥＥＥ　８０２．１１無線區域網路之兩段式通話允諾控制演算法
(2010-06-11)
黃經堯
;
施雲懷
本發明係揭示一種用於IEEE 802.11無線區域網路之兩段式通話允諾控制演算法。此兩段式通話允諾控制演算法不僅能提高IEEE802.11無線區域網路系統的整體傳輸流量，更能使每一個在此系統中的使用者，均能得到一定的服務品質。 The present invention discloses a two－tier call admission control algorithm in IEEE 802.11 WLAN. The two－tier call admission control algorithm is given to improve the overall system throughput and guarantee the quality of service of every single user in the WLAN. 【創作特點】本發明之目的在於提供一種用於IEEE 802.11無線區域網路之兩段式通話允諾控制演算法，可用以改善整個系統之傳輸流量及保證每一使用者之服務品質。根據以上目的，將針對IEEE 802.11無線區域網路的實體層及媒介存取層進行分析，並檢視IEEE 802.11無線區域網的每一個模式在不同的頻道下所能達到的最大傳輸流量，且利用馬可夫鍊來導出連線速率自動調節演算法的數學模型。本發明提出一種用於IEEE 802.11無線區域網路之兩段式通話允諾控制演算法，該兩段式通話允諾演算法在IEEE 802.11無線區域網路中係用以允諾提供具有高品質服務要件之服務請求，此演算法包含以下步驟：使單一使用者及整個系統各自對應於一第一層測試及一第二層測試。由於本發明採用兩段式來處理使用者及系統之演算法，因此可改善整個系統之傳輸流量及保證每一使用者之服務品質。為讓本發明之上述和其他目的、特徵及優點能更明顯易懂，下文特舉較佳實施例，並配合所附圖式，作詳細說明如下。
Engineered spin-state transitions of two interacting electrons in semiconductor nanowire quantum dots
(2010-06-11)
Chen, Yan-Ting
;
Cheng, Shun-Jen
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Tang, Chi-Shung
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電子物理學系
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Department of Electrophysics
Spin properties of two interacting electrons in a quantum dot (QD) embedded in a nanowire with controlled aspect ratio and longitudinal magnetic fields are investigated by using a configuration-interaction (CI) method. The developed CI theory based on a three-dimensional parabolic model provides explicit formulations of the Coulomb matrix elements and allows for straightforward and efficient numerical implementation. Our studies reveal fruitful features of spin-singlet-triplet transitions of two electrons confined in a nanowire QD, as a consequence of the competing effects of geometry-controlled kinetic-energy quantization, Coulomb interaction, and spin-Zeeman energy. The developed theory is further employed to study various spin states of two quantum-confined electrons in the regime of "crossover" dimensionality, from quasi-two-dimensional (disklike) QDs to finite one-dimensional (rodlike) QDs.
Mobile-Taiwan experience in voice over IP-worldwide interoperability for microwave access trial
(2010-06-11)
Lin, Y. -B.
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Sung, Y. -C.
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Rashvand, H. F.
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Liu, C. -L.
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Liao, Y. -J.
Considering voice as a dominant telecommunication service, the performance of Voice over IP (VoIP) plays a critical role in deployment of worldwide interoperability for microwave access (WiMAX) technology providing all-IP network services. To that effect, in this study, the authors investigate the performance of a WiMAX-based VoIP established under the mobile Taiwan (M-Taiwan) field-trial funded program. To achieve the objectives of the trial the measurement results expressed in the form of mean opinion score (MOS), packet loss, packet delay and jitters. For the worst-case scenario, the tests were conducted under a stringent condition of both communicating devices, wirelessly connected to the same WiMAX base station under a heavy background traffic and interference, were experiencing simultaneous handovers during the communication. Upon their analysis, the field measurements confirm an excellent performance when both communicating devices kept stationary and show an acceptable quality for the service when both communicating devices are on the move at a speed of 50 km/h.
Cardiorespiratory phase synchronization during normal rest and inward-attention meditation
(2010-06-11)
Wu, Shr-Da
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Lo, Pei-Chen
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電控工程研究所
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Institute of Electrical and Control Engineering
Performance enhancement and analysis for IEEE 802.16e/m sleep mode operations with unsolicited grant service/real-time variable-rate connections
(2010-06-11)
Hsu, C. -H.
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Feng, K. -T.
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電機工程學系
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Department of Electrical and Computer Engineering
The power saving class of type II (PSC II), one of the sleep mode operations in the IEEE 802.16e standard, is designed to reduce power consumption for unsolicited grant service (UGS) and real-time variable-rate (RT-VR) connections. However, the configuration of fixed-length listening windows in the PSC II incurs unnecessary energy consumption or packet loss for these types of connections. In order to enhance the performance of sleep mode operations, an approach with adaptive listening window (ALW) is proposed. The ALW scheme dynamically adjusts the length of each listening window based on the number of both arrival and retransmission packets as well as the delay constraint. Numerical analysis and simulation results show that the proposed ALW approach can effectively reduce the packet loss rate for UGS connections, whereas better energy conservation with reduced packet loss rate is achieved for RT-VR connections.
Effect of scattering on zero-bias anomaly and conductance reduction in quasi-one-dimensional quantum wires
(2010-06-11)
Liu, K. M.
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Umansky, V.
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Hsu, S. Y.
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電子物理學系
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Department of Electrophysics
We present a systematic study on the zero-bias conductance peak and its dependences on the carrier density and structural geometry in quasi-one-dimensional quantum wires (QWs). This zero-bias anomaly (ZBA) is suppressed by either decreasing the carrier density or increasing the QW length. The differential conductance at zero bias decreases with increasing temperature in accordance with a thermal-activation model up to a well-defined cut-off temperature. We demonstrate that the activation energy, cut-off temperature, and width of the ZBA are correlated, and suggest that these features are controlled by electron scattering in QWs.
Photocatalysis by Electron Transfer between Different-sized Anatases
(2010-06-15)
Ke, Tsung-Ying
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Lee, Chi-Young
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Chiu, Hsin-Tien
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應用化學系
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Department of Applied Chemistry
In the solution state, photocatalysis of micro- and nano-sized anatases can be optimized at flat band and in a high pH solution, respectively. Furthermore, a remarkable photocatalyst that can be adopted over a wide range of pH values was produced by mixing commercial micro- and nano-sized anatases. Mixing causes the electron transfer between the identical phase but different-sized TiO(2) particles, subsequently separating the electrons and holes, as well as greatly facilitating photocatalysis. As is well known, the commercially available photocatalyst P25, a mixture of anatase and rutile, achieves a superior photocatalytic performance from pH 3 to 10, owing to the electron transfer between the various phases. This study elucidates these mixed photocatalysts, P25 and mixture of micro and nano-sized anatases. Crown Copyright (C) Published by Elsevier B.V. All rights reserved.
Degradation of carbofuran in aqueous solution by ultrasound and Fenton processes: Effect of system parameters and kinetic study
(2010-06-15)
Ma Ying-Shih
;
Sung Chi-Fanga
;
Lin Jih-Gaw
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環境工程研究所
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Institute of Environmental Engineering
To establish an efficient oxidation process for carbofuran degradation, the effects of some operating parameters such as dosages of H(2)O(2), Fe(2+) and initial carbofuran concentrations were observed during carbofuran degradation by the ultrasound process, Fenton process and a combined ultrasound/Fenton process. The degradation kinetics of carbofuran was also examined based on the experimental data. The results show that more than 99% of the carbofuran was degraded by the ultrasound/Fenton process within short reaction time periods. Increased dosages of H(2)O(2) and Fe(2+) enhanced the degradation of carbofuran in the ultrasound and Fenton oxidation processes, but initial carbofuran concentrations decreased carbofuran degradation in both the Fenton and ultrasound/Fenton processes. The degradation kinetics of carbofuran by the three oxidation processes was found to be in accordance with first-order reaction kinetics. The results provide fundamental information about the treatment of carbofuran wastewater and/or other pesticides by the ultrasound/Fenton oxidation process. (C) 2010 Elsevier B.V. All rights reserved.
Remarkable Photothermal Effect of Interband Excitation on Nanosecond Laser-Induced Reshaping and Size Reduction of Pseudospherical Gold Nanoparticles in Aqueous Solution
(2010-06-15)
Werner, Daniel
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Hashimoto, Shuichi
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Uwada, Takayuki
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應用化學系
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應用化學系分子科學碩博班
An in situ spectroscopic study of the nanosecond laser-induced melting and size reduction of pseudospherical gold nanoparticles with 54 +/- 7 nm diameter allowed the observation of a heating efficiency that was very dependent on the excitation wavelength. A remarkably greater efficiency was observed for the photothermal effect of interband excitation than that of intraband excitation. This noteworthy observation is ascribed to an altered electron heat capacity, c(e), during photoexcitation depending on the excitation energy, which is a phenomenon that has not been realized previously. As a result, a 60% reduction of the specific heat capacity, c(p), compared to that of bulk gold was obtained for interband excitation at 266 nm whereas the c(p) value for the excitation of the intraband transition at 532 nm was unaltered. A semiquantitative explanation was given for this striking phenomenon induced by interband excitation in which excitation relaxation cycles of electrons upon excitation of 5d electrons to the 6sp band lead to a reduced number of electrons contributing to the electron temperature rise in the vicinity of the Fermi level during the nanosecond laser pulse duration. By contrast, electronic-excitation within the 6sp band results in no net reduction in the number of electrons near the Fermi level, giving rise to a value of c(p) similar to that of bulk gold. Our finding that the heat capacity of gold nanoparticles can be changed upon UV laser excitation is important for understanding the fundamental nature of noble metal nanoparticles. Furthermore, this finding might be useful for preparing new metal alloy particles as well as for manipulating the thermodynamic properties of the nanoparticles.
Star Block Copolymers Through Nitroxide-Mediated Radical Polymerization From Polyhedral Oligomeric Silsesquioxane (POSS) Core
(2010-06-15)
Lu, Chu-Hua
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Wang, Jui-Hsu
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Chang, Feng-Chih
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Kuo, Shiao-Wei
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應用化學系
A series of star block copolymers were prepared through nitroxide-mediated radical polymerization (NMRP) from polyhedral oligomeric silsesquioxanes (POSS) nanoparticle by core-first polymerization. Eight N-alkoxyamine groups were incorporated onto the eight corners of a POSS cube through quantitative hydrosilylation through addition of octakis(dimethylsiloxy)silsesquioxane (O(8)M(8)(H) POSS) with 1-(2-(allyloxy)-1-phenylethoxy)-2,2,6,6-tetramethyl-piperidine (allyl-TEMPO) and Karstedt's agent (a platinum divinylsiloxane complex) was used as a catalyst. Octa-N-alkoxyamines POSS (OT-POSS) were used as platform to synthesize star polystyrene-POSS ((PS)(8)-POSS) homopolymer and diblock copolymers of poly(styrene-block-4-vinyl-pyridine)-POSS ((PS-b-P4VP)(8)-POSS) and poly(styrene-block-acetoxystyrene) ((PS-b-PAS)(8)-POSS) through NMRP. In addition, subsequent selective hydrolysis of the acetyl protective group of (PS-b-PAS)(8)-POSS, the poly(styrene-block-vinyl phenol) ((PS-b-PVPh)(8)-POSS) with strong hydrogen bonding group was obtained. The detailed chemical structure and self-assembled structures of these star block copolymers based on POSS were characterized by (1)H NMR, FTIR, SEC, TEM, and SAXS analyses.
Co-existence of anammox and denitrification for simultaneous nitrogen and carbon removal-Strategies and issues
(2010-06-15)
Kumar, Mathava
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Lin, Jih-Gaw
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環境工程研究所
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Institute of Environmental Engineering
The discovery of anaerobic ammonium oxidation (anammox) has greatly improved the understanding of the nitrogen cycle. Anammox provides great promise for the removal of nitrogen from wastewater, containing high concentration of ammonium. However, the presence of organic carbon is considered as unfavorable to this autotrophic process, i.e. anammox. Most of the real wastewaters contain both organic carbon and nitrogen. Under this circumstance, several processes have been established primarily for the complete removal of organic carbon. Subsequently, the wastewater containing no or low organic carbon and nitrogen is treated via a variety of nitrogen removal processes. The co-existence of anammox and denitrification could be useful for the simultaneous removal of nitrogen and organic carbon in a single system rather than a sequential chain of treatment. This review addresses the microbiology, strategies, consequences and the future research challenges in the co-existence of anammox and denitrification. (C) 2010 Elsevier B.V. All rights reserved.