Browsing by Issue Date, starting with "2011-03-28"

Now showing 1 - 20 of 41847

Heterogeneous radio-over-fiber passive access network architecture to mitigate Rayleigh backscattering interferometric beat noise
(2011-03-28)
Yeh, C. H.
;
Chow, C. W.
;
光電工程學系
;
Department of Photonics
We propose and experimentally demonstrate a hybrid radio-over-fiber (ROF) wavelength division multiplexed and time division multiplexed passive optical network (WDM-TDM PON) architecture to mitigate Rayleigh backscattering (RB) interferometric beat noises. Here, only a single wavelength is needed at the central office (CO) to generate the downstream baseband data for optical wired application and optical millimeter-wave (mm-wave) signal for wireless application. The upstream signal is produced by remodulating the downstream signal. No optical filter is required at the optical network unit/remote antenna unit (ONU/RAU) to separate the optical wired and optical mm-wave signals. In the proposed network, 10 Gb/s differential phase shift keying (DPSK) signal is used for the downstream optical wired application and 2.5 Gb/s on-off keying (OOK) signal on 20 GHz carrier is used for the optical mm-wave signal. In each ONU, a reflective optical semiconductor amplifier (RSOA) is used to remodulate and produce a 2.5 Gb/s OOK format for upstream traffic. As the back-refection produced by the downstream DPSK signal and the upstream OOK signal is traveling in different fiber path, RB noise at the CO can be completely mitigated (c) 2011 Optical Society of America
Lasing in metal-coated GaN nanostripe at room temperature
(2011-03-28)
Wang, Yow-Gwo
;
Chen, Cheng-Chang
;
Chiu, Ching-Hsueh
;
Kuo, Ming-Yen
;
Shih, M. H.
This study demonstrated a metal-coated GaN nanostripe laser operable at room temperature. The ultraviolet lasing mode was observed at a wavelength of approximately 370 nm with a low threshold power density of 0.042 kW/cm(2). The lasing mode of the metal-coated nanostripe was characterized using finite-element method simulation. The results showed the significance of metal coatings in this nanocavity structure for lasing at room temperature. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3572023]
Infrared absorption of CH3SO2 observed upon irradiation of a p-H-2 matrix containing CH3I and SO2
(2011-03-28)
Lee, Yu-Fang
;
Lee, Yuan-Pern
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
Irradiation with a mercury lamp at 254 nm of a p-H-2 matrix containing CH3I and SO2 at 3.3 K, followed by annealing of the matrix, produced prominent features at 633.8, 917.5, 1071.1 (1072.2), 1272.5 (1273.0, 1273.6), and 1416.0 cm(-1), attributable to nu(11) (C-S stretching), nu(10) (CH3 wagging), nu(8) (SO2 symmetric stretching), nu(7) (SO2 antisymmetric stretching), and nu(4) (CH2 scissoring) modes of methylsulfonyl radical (CH3SO2), respectively; lines listed in parentheses are weaker lines likely associated with species in a different matrix environment. Further irradiation at 365 nm diminishes these features and produced SO2 and CH3. Additional features at 1150.1 and 1353.1 (1352.7) cm(-1) are tentatively assigned to the SO2 symmetric and antisymmetric stretching modes of ISO2. These assignments are based on comparison of observed vibrational wavenumbers and O-18- and S-34-isotopic shifts with those predicted with the B3P86 method. Our results agree with the previous report of transient IR absorption bands of gaseous CH3SO2 at 1280 and 1076 cm(-1). These results demonstrate that the cage effect of solid p-H-2 is diminished so that CH3 radicals, produced via UV photodissociation of CH3I in situ, might react with SO2 to form CH3SO2 during irradiation and upon annealing. Observation of CH3SO2 but not CH3OSO is consistent with the theoretical predictions that only the former reactions proceed via a barrierless path. (C) 2011 American Institute of Physics. [doi:10.1063/1.3567117]
Infrared absorption of CH(3)SO(2) observed upon irradiation of a p-H(2) matrix containing CH(3)I and SO(2)
(2011-03-28)
Lee, Yu-Fang
;
Lee, Yuan-Pern
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
Irradiation with a mercury lamp at 254 nm of a p-H(2) matrix containing CH(3)I and SO(2) at 3.3 K, followed by annealing of the matrix, produced prominent features at 633.8, 917.5, 1071.1 (1072.2), 1272.5 (1273.0, 1273.6), and 1416.0 cm(-1), attributable to nu(11) (C-S stretching), nu(10) (CH(3) wagging), nu(8) (SO(2) symmetric stretching), nu(7) (SO(2) antisymmetric stretching), and nu(4) (CH(2) scissoring) modes of methylsulfonyl radical (CH(3)SO(2)), respectively; lines listed in parentheses are weaker lines likely associated with species in a different matrix environment. Further irradiation at 365 nm diminishes these features and produced SO(2) and CH(3). Additional features at 1150.1 and 1353.1 (1352.7) cm(-1) are tentatively assigned to the SO(2) symmetric and antisymmetric stretching modes of ISO(2). These assignments are based on comparison of observed vibrational wavenumbers and (18)O- and (34)S-isotopic shifts with those predicted with the B3P86 method. Our results agree with the previous report of transient IR absorption bands of gaseous CH(3)SO(2) at 1280 and 1076 cm(-1). These results demonstrate that the cage effect of solid p-H(2) is diminished so that CH(3) radicals, produced via UV photodissociation of CH(3)I in situ, might react with SO(2) to form CH(3)SO(2) during irradiation and upon annealing. Observation of CH(3)SO(2) but not CH(3)OSO is consistent with the theoretical predictions that only the former reactions proceed via a barrierless path. (C) 2011 American Institute of Physics. [doi:10.1063/1.3567117]
Effect of Si doping and applied pressure upon magnetostructural properties of Tb-5(SixGe1-x)(4) magnetocaloric compounds
(2011-03-28)
Tseng, Yuan-Chieh
;
Ma, Hao-Jhong
;
Yang, Chao-Yao
;
Mudryk, Yaroslav
;
Pecharsky, Vitalij K.
The composition-and pressure-dependent magnetostructural properties of Tb-5(SixGe1-x)(4) (x = 0.4, 0.485, 0.625, and 0.7) were investigated using x-ray powder diffraction and x-ray magnetic circular dichroism in a diamond anvil cell, respectively. Substituting the smaller-size Si for Ge stabilizes a single-phase, ferromagnetic (FM) orthorhombic O(I) structure for x >= 0.7. Similarly, application of external pressure causes a canted antiferromagnetic orthorhombic O(II) sample (x=0.4) to transform into an FMO(I) phase at 4 GPa. The element- and orbital-specific x-ray absorption data indicate that the Tb 4f orbital occupation changes with external pressure, likely through 4f-5d electronic mixing, yet no changes in Tb 4f electronic structure are observed with Si doping. The results point to different mechanisms behind the enhancement of FM exchange interactions in Tb-5(SixGe1-x)(4) with chemical and applied pressure, respectively.
Effect of Si doping and applied pressure upon magnetostructural properties of Tb(5)(Si(x)Ge(1-x))(4) magnetocaloric compounds
(2011-03-28)
Tseng, Yuan-Chieh
;
Ma, Hao-Jhong
;
Yang, Chao-Yao
;
Mudryk, Yaroslav
;
Pecharsky, Vitalij K.
The composition-and pressure-dependent magnetostructural properties of Tb(5)(Si(x)Ge(1-x))(4) (x = 0.4, 0.485, 0.625, and 0.7) were investigated using x-ray powder diffraction and x-ray magnetic circular dichroism in a diamond anvil cell, respectively. Substituting the smaller-size Si for Ge stabilizes a single-phase, ferromagnetic (FM) orthorhombic O(I) structure for x >= 0.7. Similarly, application of external pressure causes a canted antiferromagnetic orthorhombic O(II) sample (x=0.4) to transform into an FMO(I) phase at 4 GPa. The element- and orbital-specific x-ray absorption data indicate that the Tb 4f orbital occupation changes with external pressure, likely through 4f-5d electronic mixing, yet no changes in Tb 4f electronic structure are observed with Si doping. The results point to different mechanisms behind the enhancement of FM exchange interactions in Tb(5)(Si(x)Ge(1-x))(4) with chemical and applied pressure, respectively.
Evolution of the pseudogap in Sr1-xYxAl2Si2 (x=0, 0.05, 0.1, and 0.15) probed via Al-27 nuclear magnetic resonance
(2011-03-28)
Fang, C. P.
;
Lue, C. S.
;
Young, Ben-Li
;
電子物理學系
;
Department of Electrophysics
With the aim of providing microscopic information about the electronic characteristics of SrAl2Si2 and effects of chemical substitution on its pseudogap features, we carried out a study on Sr1-xYxAl2Si2 (x = 0, 0.05, 0.1, and 0.15) by means of Al-27 nuclear magnetic resonance (NMR) spectroscopy. For stoichiometric SrAl2Si2, the temperature-dependent NMR Knight shift and spin-lattice relaxation rate are associated with a sharp feature in the electronic density of state within a pseudogap at around the Fermi level. On the other hand, the NMR observations for Y-substituted compounds exhibit ordinary metallic behavior, suggesting that the Fermi level has moved out of the pseudogap for these materials, resulting in the dominant Korringa process responsible for the observed relaxation rates.
Evolution of the pseudogap in Sr(1-x)Y(x)Al(2)Si(2) (x=0, 0.05, 0.1, and 0.15) probed via (27)Al nuclear magnetic resonance
(2011-03-28)
Fang, C. P.
;
Lue, C. S.
;
Young, Ben-Li
;
電子物理學系
;
Department of Electrophysics
With the aim of providing microscopic information about the electronic characteristics of SrAl(2)Si(2) and effects of chemical substitution on its pseudogap features, we carried out a study on Sr(1-x)Y(x)Al(2)Si(2) (x = 0, 0.05, 0.1, and 0.15) by means of (27)Al nuclear magnetic resonance (NMR) spectroscopy. For stoichiometric SrAl(2)Si(2), the temperature-dependent NMR Knight shift and spin-lattice relaxation rate are associated with a sharp feature in the electronic density of state within a pseudogap at around the Fermi level. On the other hand, the NMR observations for Y-substituted compounds exhibit ordinary metallic behavior, suggesting that the Fermi level has moved out of the pseudogap for these materials, resulting in the dominant Korringa process responsible for the observed relaxation rates.
雙身共存的天使：卡拉馬助夫兄弟們
(2011-03-30)
阮慶岳
;
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。
Mechanistic Aspect of Surface Modification on Glass Substrates Assisted by Single Shot Pulsed Laser-Induced Fragmentation of Gold Nanoparticles
(2011-03-31)
Hashimoto, Shuichi
;
Uwada, Takayuki
;
Hagiri, Masahide
;
Shiraishi, Ryowya
;
應用化學系
This paper describes the mechanistic investigation on the photomodification of a borosilicate glass substrate assembled with 47 +/- 8 nm gold nanoparticles and exposed to a single shot of 532 nm nanosecond pulsed-laser light. The laser fluences ranging from 180 to 430 mJ cm(-2) pulse(-1), the values of which are 2 orders of magnitude lower than the breakdown threshold of quartz of 15-20 J cm(-2) pulse(-1) were used. Upon photomodification, the craters of similar to 20 nm diameter and similar to 10 tun depth were formed on the glass surface simultaneously with the laser-induced splitting of Au nanopartides to generate smaller particles of 15 nm diameter. The number density of the craters increased depending on the laser fluence with a sharp rise, the onset of which occurred at similar to 160-170 mJ cm(-2) pulse(-1), and reached a value of twice the number density of original Au particles (150 +/- 10 particles mu m(-2)) with a weak tendency to level off at high fluences. The onset of the crater formation coincides with splitting of gold nanopartides due to the temperature rise above the boiling point of gold resulting from the absorption of the laser energy. Thus, the explosive evaporation of gold nanoparticles is postulated to play a crucial role for the modification observed here. This assumption gained a solid support from the estimation of laser fluence-dependent thermoacoustic pressures due to the sudden evaporation of gold. This finding may represent a new application of the laser ablation/fragmentation of nanoparticles to material processing.
Influence of hydrogen plasma treatment on charge storage characteristics in high density tungsten nanocrystal nonvolatile memory
(2011-03-31)
Chen, Shih-Cheng
;
Chang, Ting-Chang
;
Chen, Wei-Ren
;
Lo, Yuan-Chun
;
Wu, Kai-Ting
This study focuses on the influence of a hydrogen plasma treatment on electrical properties of tungsten nanocrystal nonvolatile memory. The X-ray photon emission spectra show that, after the hydrogen plasma treatment, a change in binding energy occurs such that Si(x+) and Si(y+) peaks appear at a position that is shifted about 2.3 and 3.3 eV from Si(o+) in Si 2p spectra. This indicates that Si dangling bonds are passivated to form a Si-H bond structure in the SiO(2). Furthermore, the transmission electron microscopy shows cross-sectional and plane-view for the nanocrystal microstructure after the hydrogen plasma treatment. Electrical measurement analyses show improved data retention because the hydrogen plasma treatment enhances the quality of the oxide surrounding the nanocrystals. The endurance and retention properties of the memory device are improved by about 36% and 30%, respectively. (C) 2011 Elsevier By. All rights reserved.
Geometry of classical periodic orbits and quantum coherent states in coupled oscillators with SU(2) transformations
(2011-03-31)
Chen, Y. F.
;
電子物理學系
;
Department of Electrophysics
The geometry of classical dynamics in coupled oscillators with SU(2) transformations is explored and found to be relevant to a family of continuous-transformation orbits between Lissajous and trochoidal curves. The quantum wave-packet coherent states are derived analytically to correspond exactly to the transformation geometry of classical dynamics. By using the quantum wave-packet coherent states derived herein, stationary coherent states are constructed and are shown to possess spatial patterns identical to the transformation geometry between Lissajous and trochoidal orbits.
BIOSENSOR AND ELECTRODE STRUCTURE THEREOF
(2011-03-31)
Liao, Lun-De
;
Chen, Yu-Han
;
Chao, Paul C.-P.
;
Lin, Chin-Teng
;
Sun, Arch
An electrode structure of a biosensor includes a flexible conductive substrate and a plurality of conductive probes protruding from the conductive substrate and configured for contacting a subject and receiving a physiological electric wave signal therefrom. The present invention improves disadvantages of wet electrodes and microstructure electrodes and provides more stable signals that may less decay with time so as to achieve real-time and long-acting measurement for physiological electric wave signal. A biosensor using the electrode structure is also disclosed.
Massive superstring scatterings in the Regge regime
(2011-03-31)
He, Song
;
Lee, Jen-Chi
;
Takahashi, Keijiro
;
Yang, Yi
;
電子物理學系
We calculate four classes of high-energy massive string scattering amplitudes of fermionic string theory at arbitrary mass levels in the Regge regime (RR). We show that all four leading order amplitudes in the RR can be expressed in terms of the Kummer function of the second kind. Based on the summation algorithm of a set of extended signed Stirling number identities, we show that all four ratios calculated previously by the method of decoupling of zero-norm states among scattering amplitudes in the Gross regime can be extracted from this Kummer function in the RR. Finally, we conjecture and give evidence that the existence of these four Gross regime ratios in the RR persists to subleading orders in the Regge expansion of all high-energy fermionic string scattering amplitudes.
資本支出宣告與產業資訊移轉：由知識資本與價值鏈之影響論析
(2011-04-01)
王曉雯
;
李書行
;
吳明政
;
Hsiao-Wen Wang
;
Shu-Hsing Li
企業發生重大事件，或者是宣告相關營運訊息，此項資訊不但會影響公司股價表現，通常亦會影響產業內其它競爭對手的股價報酬。本文以台灣資訊電子業爲樣本，探討高科技公司揭露資本支出產生的資訊內涵與資訊移轉效果是否將會受到宣告公司的知識資本與產業價值鏈階段所影響。實證結果可歸納如下：(1)企業資本支出宣告具有資訊內涵；資本市場將自願性資本支出宣告解讀爲公司向投資人傳遞有利前景之財務報表補充訊息。(2)相較於擁有低知識資本品質企業，投資人對於高知識資本品質公司宣告資本支出，平均而言，將會給予較大股價反應。(3)相較於處在產業價值鏈中；下游企業，投資人對於價值鏈上游公司宣告資本支出，平均而言，將會給予較大股價反應。(4)相較於高知識資本品質（產業價值鏈上游）企業，隨著資本支出宣告窗期逐漸拉長，低知識資本品質（產業價值鏈中；下游）公司宣告資本支出對同產業競爭公司股價異常報酬將會由蔓延效果轉變成爲競爭效果。
Tunable Light Emission from GaN-Based Photonic Crystal with Ultraviolet AlN/AlGaN Distributed Bragg Reflector
(2011-04-01)
Chen, Cheng-Chang
;
Chiu, Ching-Hsueh
;
Yang, Yi-Chun
;
Shih, M. H.
;
Chen, Jun-Rong
In this paper, the characteristics of GaN-based two-dimensional (2D) photonic crystal bandedge coupling operation with an ultraviolet AlN/AlGaN distributed Bragg reflector (DBR) have been investigated and analyzed. The 25-pair AlN/Al(0.2)GaN(0.8) DBR shows a high reflectivity of 85% at 375nm with the stop-band width of 15nm. A strong light emission was observed from GaN photonic crystals within high reflectivity region of DBR. The emission wavelength can be also manipulated by varying the radius to lattice constant ratio. The photonic crystal bandedge mode was also characterized with three-dimensional plane-wave expansion (PWE) and finite-difference time-domain (FDTD) simulation. (C) 2011 The Japan Society of Applied Physics
Phase-Change Kinetics of Bi-Fe-(N) Layer for High-Speed Write-Once Optical Recording
(2011-04-01)
Huang, Sung-Hsiu
;
Huang, Yu-Jen
;
Mai, Hung-Chuan
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
In this work, we present the phase-change kinetics of Bi-Fe-(N) layers for write-once optical recording. In situ reflectivity measurement indicated that the phase-change temperature (T(x)) of the Bi-Fe-(N) layers is strongly related to the heating rate. The T(x)'s were about 170 degrees C at low heating rates and approached the melting point of the Bi phase (i.e., 271.4 degrees C) at high rate of heating provided by laser heating. For a 100-nm-thick Bi-Fe-(N) layer, Kissinger's analysis showed that the activation energy of phase transition (E(a)) = 1.24 eV, while the analysis of isothermal phase transition in terms of the Johnson-Mehl-Avrami (JMA) theory showed that the average Avrami exponent (m) = 2.2 and the appropriate activation energy (Delta H) = 5.15 eV. With the aid of X-ray diffraction (XRD) analysis, a two-dimensional phase transition behavior in the Bi-Fe-(N) layers initiated by the melting of the Bi-rich phase was confirmed. For optical disk samples with optimized disk structure and write strategy, the signal properties far exceeding the write-once disk test specifications were achieved. Satisfactory signal properties indicated that the Bi-Fe-(N) system is a promising alternative for high-speed write-once recording in the Blu-ray era. (C) 2011 The Japan Society of Applied Physics
以單晶氧化物作為基板成長纖鋅礦結構半導體非極性ｍ面磊晶層之方法
(2011-04-01)
張立
;
何焱騰
本發明係有關於一種以單晶氧化物作為基板成長非極性m面磊晶層之方法,包括:提供一具有鈣鈦礦結構之單晶氧化物;選擇該單晶氧化物之一平面作為一基板;以及在該基板上以氣相沉積法生長一具有纖鋅礦結構半導體之非極性m面磊晶層。本發明亦提供一種以前述方法成長之具有非極性m面之磊晶層。
Linear coherent distributed estimation over unknown channels
(2011-04-01)
Wu, Chien-Hsien
;
Lin, Ching-An
;
電控工程研究所
;
Institute of Electrical and Control Engineering
We study linear distributed estimation with coherent multiple access channel model and MMSE fusion rule. The flat fading channels are assumed unknown at the fusion center and need to be estimated. We adopt a two-phase approach, which first estimates channels and then estimates the source signal, to minimize the MSE of the estimated signal. We study optimal power allocation under a total network power constraint. We consider the optimal power allocation scheme in which training power and data power for each sensor are optimized, and the equal power allocation scheme in which training power is optimized while data power for each sensor is set equal. In both schemes, the problem is formulated as a constrained optimization problem and analytical closed-form solution is obtained. Analytic results reveal that (i) with estimated channels, the MSE approaches to a finite nonzero value as the number of sensors increases: (ii) the optimal training powers are the same in both schemes: (iii) the MSE performance compared with the case when channels are known shows the penalty caused by channel estimation becomes worse as the number of sensors increases. Simulation results verify our findings. (C) 2010 Elsevier B.V. All rights reserved.
A CMOS 6-Bit 16-GS/s Time-Interleaved ADC Using Digital Background Calibration Techniques
(2011-04-01)
Huang, Chun-Cheng
;
Wang, Chung-Yi
;
Wu, Jieh-Tsorng
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An 8-channel 6-bit 16-GS/s time-interleaved analog-to-digital converter (TI ADC) was fabricated using a 65 nm CMOS technology. Each analog-to-digital channel is a 6-bit flash ADC. Its comparators are latches without the preamplifiers. The input-referred offsets of the latches are reduced by digital offset calibration. The TI ADC includes a multi-phase clock generator that uses a delay-locked loop to generate 8 sampling clocks from a reference clock of the same frequency. The uniformity of the sampling intervals is ensured by digital timing-skew calibration. Both the offset calibration and the timing-skew calibration run continuously in the background. At 16 GS/s sampling rate, this ADC chip achieves a signal-to-distortion-plus-noise ratio (SNDR) of 30.8 dB. The chip consumes 435 mW from a 1.5 V supply. The ADC active area is 0.93 x 1.58 mm(2).