Browsing by Issue Date, starting with "2012-04-23"

Now showing 1 - 20 of 36682

Effects of edge potential on an armchair-graphene open boundary and nanoribbons
(2012-04-23)
Chiu, Chi-Hsuan
;
Chu, Chon-Saar
;
電子物理學系
;
Department of Electrophysics
Pseudospin flipping is found to be the key process leading to the formation of an edge-potential-induced edge state at an armchair-graphene open boundary and nanoribbons. At an open boundary, the edge potential U-0 is shown to turn on pseudospin-flipped (intravalley) scattering even though U-0 does not post an apparent breaking of the AB site (basis atoms) symmetry. For a valley-polarized incident beam, the interference between the pseudospin-conserving (intervalley) and -nonconserving (intravalley) processes in the scattering state leads to a finite out-of-plane pseudospin density. This two-wave feature in the evanescent regime leads to the formation of the edge state. The physical origin of the edge state is different from that for the Tamm states in semiconductors. For an armchair-graphene nanoribbon with a gapless energy spectrum, applying U-0 to both edges opens up an energy gap. Both edge states and energy gap opening exhibit distinct features in nanoribbon conductance.
Wide-angle polarization independent infrared broadband absorbers based on metallic multi-sized disk arrays
(2012-04-23)
Cheng, Cheng-Wen
;
Abbas, Mohammed Nadhim
;
Chiu, Chao-Wei
;
Lai, Kun-Ting
;
Shih, Min-Hsiung
Two-dimensional metallic broadband absorbers on a SiO2/Ag/Si substrate were experimentally studied. The absorptivity of such structure can be increased by tailoring the ratio of disk size to the unit cell area. The metallic disk exhibits a localized surface plasmon polariton (LSPP) mode for both TE and TM polarizations. A broadband thermal emitter can be realized because the LSPP mode is independent of the periodicities. By manipulating the ratios and disk sizes, a high-performance, wide-angle, polarization-independent dual band absorber was experimentally achieved. The results demonstrated a substantial flexibility in absorber designs for applications in thermal photovoltaics, sensors, and camouflage. (C) 2012 Optical Society of America
Observation of Electron-Antineutrino Disappearance at Daya Bay
(2012-04-23)
An, F. P.
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Bai, J. Z.
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Balantekin, A. B.
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Band, H. R.
;
Beavis, D.
The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle 0(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GW(th) reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43 000 ton-GW(th)-day live-time exposure in 55 days, 10 416 (80 376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R = 0.940 +/- 0.011(stat.) +/- 0.004(syst.). A rate-only analysis finds sin(2)2 theta(13) = 0.092 +/- 0.016(stat.) +/- 0.005(syst.) in a three-neutrino framework.
Electrical and reliability characteristics of polycrystalline silicon thin-film transistors with high-kappa Eu2O3 gate dielectrics
(2012-04-23)
Yen, Li-Chen
;
Hu, Chia-Wei
;
Chiang, Tsung-Yu
;
Chao, Tien-Sheng
;
Pan, Tung-Ming
In this study, we developed a high-performance low-temperature polycrystalline silicon thin-film transistor (LTPS-TFT) incorporating an ultra thin Eu2O3 gate dielectric. High-kappa Eu2O3 LTPS-TFT annealed at 500 degrees C exhibits a low threshold voltage of 0.16 V, a high effective carrier mobility of 44 cm(2)/V-s, a small subthreshold swing of 142 mV/decade, and a high I-on/I-off current ratio of 1.34 x 10(7). These significant improvements are attributed to the high gate-capacitance density due to the adequate quality of Eu2O3 gate dielectric with small interfacial layer of effective oxide thickness of 2.5 nm. Furthermore, the degradation mechanism of positive bias temperature instability was studied for a high-k Eu2O3 LTPS-TFT device. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4705472]
Label-free tetra-modal molecular imaging of living cells with CARS, SHG, THG and TSFG (coherent anti-Stokes Raman scattering, second harmonic generation, third harmonic generation and third-order sum frequency generation)
(2012-04-23)
Segawa, Hiroki
;
Okuno, Masanari
;
Kano, Hideaki
;
Leproux, Philippe
;
Couderc, Vincent
We have developed a new multimodal molecular imaging system that combines CARS (coherent anti-Stokes Raman scattering), SHG (second harmonic generation), THG (third harmonic generation) and multiplex TSFG (third-order sum frequency generation) using a subnanosecond white-light laser source. Molecular composition and their distribution in living cells are clearly visualized with different contrast enhancements through different mechanisms of CARS, SHG, THG and TSFG. A correlation image of CARS and TSF reveals that the TSF signal is generated predominantly from lipid droplets inside a cell as well as the peripheral cell wall. (C) 2012 Optical Society of America
Dithienocarbazole-Based Ladder-Type Heptacyclic Arenes with Silicon, Carbon, and Nitrogen Bridges: Synthesis, Molecular Properties, Field-Effect Transistors, and Photovoltaic Applications
(2012-04-24)
Wu, Jhong-Sian
;
Cheng, Yen-Ju
;
Lin, Tai-Yen
;
Chang, Chih-Yu
;
Shih, Peng-I.
A new class of ladder-type dithienosilolo-carbazole (DTSC), dithienopyrrolo-carbazole (DTPC), and dithienocyclopenta-carbazole (DTCC) units is developed in which two outer thiophene subunits are covalently fastened to the central 2,7-carbazole cores by silicon, nitrogen, and carbon bridges, respectively. The heptacyclic multifused monomers are polymerized with the benzothiadiazole (BT) acceptor by palladium-catalyzed cross-coupling to afford three alternating donor-acceptor copolymers poly(dithienosilolo-carbazole-alt-benzothiadiazole) (PDTSCBT), poly(dithienocyclopenta-carbazole-alt-benzothiadiazole) (PDTCCBT), and poly(dithienopyrrolo-carbazole-alt-benzothiadiazole) (PDTPCBT). The silole units in DTSC possess electron-accepting ability that lowers the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of PDTSCBT, whereas stronger electron-donating ability of the pyrrole moiety in DTPC increases the HOMO and LUMO energy levels of PDTPCBT. The optical bandgaps (Egopt) deduced from the absorption edges of thin film spectra are in the following order: PDTSCBT (1.83 eV) > PDTCCBT (1.64 eV) > PDTPCBT (1.50 eV). This result indicated that the donor strength of the heptacyclic arenes is in the order: DTPC > DTCC > DTSC. The devices based on PDTSCBT and PDTCCBT exhibited high hole mobilities of 0.073 and 0.110 cm2 V-1 s-1, respectively, which are among the highest performance from the OFET devices based on the amorphous donor-acceptor copolymers. The bulk heterojunction photovoltaic device using PDTSCBT as the p-type material delivered a promising efficiency of 5.2% with an enhanced open circuit voltage, Voc, of 0.82 V.
Palm pad device for basketball training and basketball training system
(2012-04-24)
Chen Chung-Chiang
A palm pad device, for use as a training device and to be fastened to the palm of a user, includes a segregate pad having a size-adjustable elastic pad and a fastening member for fastening the segregate pad onto the palm. The palm pad device further includes a sensing recorder disposed on the fastening member for sensing and recording movement data of the palm. The elastic pad includes a thickness pad and a width pad for allowing adjustments in the thickness and width of the segregate pad. A basketball training system using the palm pad device includes a basket sensor for recording the status of successful shots, a sensing recorder disposed on the palm pad device, and a central management apparatus for receiving data transmitted from the sensing recorder and the basket sensor for conducting analysis to thereby generate a corresponding feedback event.
Resource allocation method for multi-users multiple input multiple output orthogonal frequency division multiplexing system and apparaus thereof
(2012-04-24)
Wang Li-Chun
;
Yeh Chu-Jung
The present invention is direct to the resource allocation method for MU-MIMO-OFDM system and the apparatus thereof. The MU-MIMO-OFDM system has a plurality of users and a plurality of sub-channels. The sub-channels are assigned to the users according to the capacity ratio constraints and a scheduling rule, and then the power of the user is determined according to the limit power of the MU-MIMO-OFDM system. Wherein the values of power of the sub-channels assigned to the user are the same, the scheduling rule may be Max-Min or Max Sum-Rate rule, and the allocation of the sub-channels may be user-oriented or sub-channel oriented.
Model of commensurate harmonic oscillators with SU(2) coupling interactions: Analogous observation in laser transverse modes
(2012-04-24)
Lin, Y. C.
;
Lu, T. H.
;
Huang, K. F.
;
Chen, Y. F.
;
電子物理學系
We theoretically explore the eigenstates of a coupled p:q commensurate harmonic oscillator with SU(2) coupling interactions under the canonical transformation. The spatial patterns of the high-order eigenstates are found to be markedly localized on Lissajous figures from single to multiple periodic orbits. Controlling the pumping size in large-Fresnel-number degenerate cavities, we have experimentally observed the laser transverse modes that display the wave patterns to be analogous to the derived eigenstates.
Automotive virtual surround audio system
(2012-04-24)
Bai Ming-Sian
;
Lee Chih-Chung
;
Chen Hui-Wen
An automotive virtual surround audio system is implemented in an automobile to receive left- and right-channel audio sources. A synthesizer receives the left- and right-channel audio sources to extend the sources into temporary rear-left and rear-right audio sources. A weighting device receives the left- and right-channel audio sources to perform a weighting operation and produce temporary front-left and front-right audio sources. A first filter receives the temporary front-left and front-right audio sources to perform a filtering operation and produce virtual front-left and front-right audio sources. A second filter receives the temporary rear-left and rear-right audio sources to perform a filtering operation and produce virtual rear-left and rear-right audio sources. Thus, the virtual audio image position is reproduced.
Roles of Amino Acids in the Escherichia coli Octaprenyl Diphosphate Synthase Active Site Probed by Structure-Guided Site-Directed Mutagenesis
(2012-04-24)
Chang, Keng-Ming
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Chen, Shih-Hsun
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Kuo, Chih-Jung
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Chang, Chi-Kang
;
Guo, Rey-Ting
Octaprenyl diphosphate synthase (OPPS) catalyzes consecutive condensation reactions of farnesyl diphosphate (FPP) with five molecules of isopentenyl diphosphates (IPP) to generate C-40 octaprenyl diphosphate, which constitutes the side chain of ubiquinone or menaquinone. To understand the roles of active site amino acids in substrate binding and catalysis, we conducted site-directed mutagenesis studies with Escherichia coli OPPS. In conclusion, D85 is the most important residue in the first DDXXD motif for both FPP and IPP binding through an H-bond network involving R93 and R94, respectively, whereas R94, K45, R48, and H77 are responsible for IPP binding by providing H-bonds and ionic interactions. K170 and T171 may stabilize the farnesyl carbocation intermediate to facilitate the reaction, whereas R93 and K225 may stabilize the catalytic base (MgPPi) for H-R proton abstraction after IPP condensation. K225 and K235 in a flexible loop may interact with FPP when the enzyme becomes a closed conformation, which is therefore crucial for catalysis. Q208 is near the hydrophobic part of IPP and is important for IPP binding and catalysis.
Design of the current driver for inducing radiating ground edge current in a printed circuit board
(2012-04-24)
Liu, T-I.
;
Wang, Y-S.
;
Chung, S. -J.
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電信工程研究所
;
Institute of Communications Engineering
A new current driver is proposed to effectively excite ground edge current for radiation without additional space reserved for antenna design. Since the current driver functions as a feeding structure as opposed to a radiator, it can be designed as small as possible without deteriorating the antenna radiation properties. A circuit model of the miniaturised balun (balanced to unbalanced transformer) is introduced to explain the current-inducing mechanism and to provide some valuable physical insights into the characteristics of the current driver. The effect of a shielding metal box for the proximity circuitry near the current driver is also investigated. And it is shown that the nearby shielding box has minor effect on the performance of the driver, which demonstrates the feasibility of the current driver as an effective antenna structure in a compact wireless terminal. The current driver operating at 2.45 GHz is printed on an FR4 substrate of 0.4 mm and occupies only a small area of about 4 mm by 4 mm. The simulated and measured results come to a great agreement. Nearly omni-directional radiation patterns with a peak gain of about 1 dBi are obtained. Owing to the design flexibilities and the compactness, the current driver is feasible for wireless applications.
A Vision-Based Collision Warning System by Surrounding Vehicles Detection
(2012-04-25)
Wu, Bing-Fei
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Chen, Ying-Han
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Kao, Chih-Chun
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Li, Yen-Feng
;
Chen, Chao-Jung
To provide active notification and enhance drivers' awareness of their surroundings, a vision-based collision warning system that detects and monitors surrounding vehicles is proposed in this paper. The main objective is to prevent possible vehicle collisions by monitoring the status of surrounding vehicles, including the distance to the other vehicles in front, behind, to the left and to the right sides. In addition, the proposed system collects and integrates this information to provide advisory warnings to drivers. To offer the correct notification, an algorithm based on features of edge and morphology to detect vehicles is also presented. The proposed system has been implemented in embedded systems and evaluated on real roads in various lighting and weather conditions. The experimental results indicate that the vehicle detection ratios were higher than 97% in the daytime, and appropriate for real road applications.
Inhibitory Effects of Chloroform Extracts Derived from Corbicula fluminea on the Release of Pro-inflammatory Cytokines
(2012-04-25)
Lin, Ching-Min
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Lin, Yu-Ling
;
Tsai, Nu-Man
;
Wu, Hsin-Yi
;
Ho, Shu-Yi
Corbicula fluminea, the primary freshwater bivalve cultivated in Taiwan, was formerly used as a remedy for hepatitis. Recent reports indicate that C. fluminea has many bioactivities, but it remains unknown whether C. fluminea affects inflammation. This study explored the anti-inflammatory activity of C.fluminea. C. fluminea was first treated with chloroform to obtain clam chloroform extracts (CCEs). On the basis of the assay for the release of pro-inflammatory cytokines in vitro and in vivo, the results show that the CCEs significantly lowered the release of lipopolysaccharide (LPS)-induced pro-inflammatory cytokines. Additionally, the CCEs reduced LPS-induced organ damage. Real-time polymerase chain reaction analysis suggested that CCEs inhibit the LPS-induced mRNA expression of interleukin-1 beta and tumor necrosis factor-alpha. Western blot analysis indicated that the CCEs increased expression of I kappa B and attenuated the phosphorylation of I kappa B. Gas chromatography mass spectrometry suggests that phytosterols and fatty adds are responsible for the anti-inflammatory properties of CCEs. Taken together, CCEs have the potential to be developed as an anti-inflammatory functional food.
弒母的故事:《杜瓦特家族》的國家寓言
(2012-04-25)
張淑英
;
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。
DEVICE HAVING SERIES-CONNECTED HIGH ELECTRON MOBILITY TRANSISTORS AND MANUFACTURING METHOD THEREOF
(2012-04-26)
CHANG EDWARD YI
;
HSU HENG-TUNG
A manufacturing method of a device having series-connected HEMTs is presented. Transistors are formed on a substrate and integratedly serial-connected as an integrated device by interconnection wires. Therefore, the voltage of the device is the sum of the voltages across each transistors so that the device can have high breakdown voltage.
Electron-Deficient Pyrimidine Adopted in Porphyrin Sensitizers: A Theoretical Interpretation of pi-Spacers Leading to Highly Efficient Photo-to-Electric Conversion Performances in Dye-Sensitized Solar Cells
(2012-04-26)
Guo, Meiyuan
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He, Rongxing
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Dai, Yulan
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Shen, Wei
;
Li, Ming
A mass of porphyrin sensitizers have been designed and synthesized for dye-sensitized solar cells in previous works, and almost all of them incorporated an electron-rich system as the pi-spacer. We here adopted the electron-deficient pyrimidine as an effective pi-spacer and combined a cyanoacrylic acid anchoring group, as such a design yields a more bathochromic shift of the spectral absorption of the dye and results in an improved spectral overlap with the solar spectrum and an enhanced light-harvesting efficiency. The result does tally with the performance of sensitizer adsorbing on a semiconductor. From the electron density difference plots of electron transitions, we found that not all electron transitions could make for the effective electron transfer from donor to acceptor groups, which means the sensitizer performance in dye-sensitized solar cells not only relies on the extrinsic spectral absorption intensity but also depends on the intrinsic character of electron movement related to electron excitation. Moreover, the introduction of electron-deficient pyrimidine could affect the energy levels of excited molecules in solution, further affecting the kinds of electron transfer processes. We presented several novel porphyrin sensitizers for comparison on how the pi-spacer and anchoring group influence the optical absorption, electron transfer processes, and regeneration of the oxidized dyes, thereby gaining potential dye-sensitized solar cells with highly efficient photo-to-electric conversion performances.
MULTILAYER SUBSTRATE HAVING GALLIUM NITRIDE LAYER AND METHOD FOR FORMING THE SAME
(2012-04-26)
Chang Edward Yi
;
Hsiao Yu-Lin
;
Lu Jung-Chi
The present invention provides a method for forming a multilayer substrate having a gallium nitride layer, wherein a mesh layer having a plurality of openings is formed on a substrate, and a buffer layer, three aluminum gallium nitride layers with different aluminum concentrations and a gallium nitride layer are formed in sequence on the substrate in the openings. The three aluminum gallium nitride layers with different aluminum concentrations are capable of releasing stress, decreasing cracks on the surface of the gallium nitride layer and controlling interior defects, such that the present invention provides a gallium nitride layer with larger area, greater thickness, no cracks and high quality for facilitating the formation of high performance electronic components in comparison with the prior art. The present invention further provides a multilayer substrate having a gallium nitride layer.
LOW-LATENCY ARC-TANGENT CALCULATION STRUCTURE AND CALCULATION METHOD THEREOF
(2012-04-26)
HSU TERNG-YIN
;
LAI WEI-CHI
The present invention provides a low-latency arc-tangent calculation structure and a calculation method thereof. The arc-tangent calculation structure comprises two lookup tables, a subtractor, a sign comparator, a numerical comparator and a shift encoder. The present invention divides the coordinate system into a plurality of sectors for simplifying the lookup tables. The first lookup table is used to perform logarithmic transformation so as to replace a divider with a subtractor. The second lookup table integrates an exponentiation table and an angle table to translate the output of the subtractor into arc-tangent value θ. Then, θ is shifted to a correct angle according to the output of the shift encoder.
独立温度制御付き成形構造とその成形方法
(2012-04-27)
陳仁浩
;
劉安誠