Browsing by Issue Date, starting with "2011-05-09"

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Eu2+-activated silicon-oxynitride Ca3Si2O4N2: a green-emitting phosphor for white LEDs
(2011-05-09)
Chiu, Yi-Chen
;
Huang, Chien-Hao
;
Lee, Te-Ju
;
Liu, Wei-Ren
;
Yeh, Yao-Tsung
The green-emitting phosphor Ca3Si2O4N2:Eu2+ was synthesized using a solid-state reaction. The luminescence properties, diffuse reflection spectrum, and thermal quenching were firstly studied, and a white light-emitting diode (wLED) was fabricated using the Eu2+-activated Ca3Si2O4N2 phosphor. Eu2+-doped Ca3Si2O4N2 exhibited a broad green emission band centered between 510 and 550 nm depending on the concentration of Eu2+. The optimal doping concentration of Eu2+ in Ca3Si2O4N2 was 1 mol%. The energy transfer between Eu2+ ions proceeds by an electric multipolar interaction mechanism, with a critical transfer distance of approximately 30.08 angstrom. A wLED with an color-rendering index R-a of 88.25 at a correlated color temperature of 6029 K was obtained by combining a GaN-based n-UV LED (380 nm) with the blue-emitting BaMgAl10O17:Eu2+, green-emitting Ca3Si2O4N2: Eu2+, and red-emitting CaAlSiN3:Eu2+ phosphors. The results present Ca3Si2O4N2:Eu2+ as an attractive candidate for use as a conversion phosphor for wLED applications. (C) 2011 Optical Society of America
Hybrid Q-switched Yb-doped fiber laser
(2011-05-09)
Huang, J. Y.
;
Zhuang, W. Z.
;
Huang, W. C.
;
Su, K. W.
;
Huang, K. F.
We investigate the performance of a hybrid Q-switched (HQS) fiber laser that is constructed with a low RF-power driven acousto-optic (AO) Q-switch and an AlGaInAs semiconductor saturable absorber. Compared to a pure passively Q-switched (PQS) fiber laser, the ratio of timing jitter to pulse period can be significantly reduced from 2% to 0.3% in the regime of far above threshold. On the other hand, the prelasing effect in a pure actively Q-switched fiber laser can be considerably improved. More importantly, the maximum pulse energy of the HQS fiber laser can be increased approximately 25% in comparison with the result of the PQS fiber laser. At a pump power of 24 W, the highest pulse energy is up to 0.56 mJ with the pulse duration of 50 ns at the repetition rate of 23 kHz. (C) 2011 Optical Society of America
Eu(2+)-activated silicon-oxynitride Ca(3)Si(2)O(4)N(2): a green-emitting phosphor for white LEDs
(2011-05-09)
Chiu, Yi-Chen
;
Huang, Chien-Hao
;
Lee, Te-Ju
;
Liu, Wei-Ren
;
Yeh, Yao-Tsung
The green-emitting phosphor Ca(3)Si(2)O(4)N(2):Eu(2+) was synthesized using a solid-state reaction. The luminescence properties, diffuse reflection spectrum, and thermal quenching were firstly studied, and a white light-emitting diode (wLED) was fabricated using the Eu(2+)-activated Ca(3)Si(2)O(4)N(2) phosphor. Eu(2+)-doped Ca(3)Si(2)O(4)N(2) exhibited a broad green emission band centered between 510 and 550 nm depending on the concentration of Eu(2+). The optimal doping concentration of Eu(2+) in Ca(3)Si(2)O(4)N(2) was 1 mol%. The energy transfer between Eu(2+) ions proceeds by an electric multipolar interaction mechanism, with a critical transfer distance of approximately 30.08 angstrom. A wLED with an color-rendering index R(a) of 88.25 at a correlated color temperature of 6029 K was obtained by combining a GaN-based n-UV LED (380 nm) with the blue-emitting BaMgAl(10)O(17):Eu(2+), green-emitting Ca(3)Si(2)O(4)N(2): Eu(2+), and red-emitting CaAlSiN(3):Eu(2+) phosphors. The results present Ca(3)Si(2)O(4)N(2):Eu(2+) as an attractive candidate for use as a conversion phosphor for wLED applications. (C) 2011 Optical Society of America
Enhanced angular characteristics of indium tin oxide nanowhisker-coated silicon solar cells
(2011-05-09)
Chang, Chia-Hua
;
Hsu, Min-Hsiang
;
Tseng, Ping-Chen
;
Yu, Peichen
;
Chang, Wei-Lun
Omnidirectional and broadband light harvesting is critical to photovoltaics due to the sun's movement and its wide spectral range of radiation. In this work, we demonstrate distinctive indium-tin-oxide nanowhiskers that achieve superior angular and spectral characteristics for crystalline silicon solar cells using angle-resolved reflectance spectroscopy. The solar-spectrum weighted reflectance is well below 6% for incident angles of up to 70 and for the wavelength range between 400nm and 1000nm. As a result, the nanowhisker coated solar cell exhibits broadband quantum efficiency characteristics and enhanced short-circuit currents for large angles of incidence. (C) 2011 Optical Society of America
Carbazole-Based Ladder-Type Heptacylic Arene with Aliphatic Side Chains Leading to Enhanced Efficiency of Organic Photovoltaics
(2011-05-10)
Cheng, Yen-Ju
;
Wu, Jhong-Sian
;
Shih, Ping-I
;
Chang, Chih-Yu
;
Jwo, Pei-Chi
By utilizing Friedel-Crafts cyclization, we have successfully designed and synthesized a ladder-type heptacyclic carbazole-dicyclopentathiophene (CDCT-C8) unit in which two outer thiophene subunits are covalently fastened to the central 2,7-carbazole core. The nitrogen-directing effect of the carbazole unit facilitates the intrarnolecular cydization and thereby suppresses the acid-induced dehydration, allowing us to incorporate two octyl side chains on the cyclopentadiene rings in good chemical yield. The distannyl-CDCT-C8 building block was copolymerized with benzothiadiazole (BT), dithienylbenzothiadiazole (DTBT), dithienyldiketopyrrolopyrrole (DTDPP) and quinoxaline (QX) units by Stile polymerization to afford four alternating donor acceptor copolymers, PCDCTBT-C8, PCDCTDTBT-C8, PCDCTDTDPP-C8 and PCDCTQX-C8, respectively. The device based on the PCDCTBT-C8:PG7IBM (1:3 in wt%) blend exhibited a V(oc) of 0.74 V, a J(sc) of 10.3 mA/cm(2), a FF of 60%, delivering an impressive PCE of 4.6%. This value represents one of the best performances among carbazole-based conjugated polymers in the literatures. The corresponding PCDCTBT-C8 :PC(71)BM blend showed a high hole mobility of 1.2 x 10(-3) cm(2) V(-1) s(-1), which is in good agreement with its high current density and fill factor. This improved performance is associated with the modification of the aliphatic side chains on the CDCT structure to optimize the interchain interactions for enhanced charge transporting. The devices based on PCDCTDTBT-C8, PCDCTDTDPP-C8 and PCDCTQX-C8 polymers also displayed promising efficiencies of 3.5%, 2.4%, and 1.8%, respectively.
Femtosecond pulses cleaning by transient-grating process Kerr-optical media
(2011-05-10)
Liu, Jun
;
Okamura, Kotaro
;
Kida, Yuichiro
;
Kobayashi, Talcayoshi
;
電子物理學系
We use a transient-grating (TG) process in a Kerr bulk medium to clean a femtosecond laser pulse. Using the technique, the temporal contrast of the generated TO signal is improved by more than two orders of magnitude in comparison with the incident pulse in a 0.5-mm-thick fused silica plate. The laser spectrum is smoothed and broadened, and the pulse duration is shortened simultaneously. We expect to extend this technique to a clean pulse with broadband spectral bandwidth at a wide spectral range because it is a phase-matched process.
On the Moment-Transfer Approach for Random Variables satisfying a One-Sided Distributional Recurrence
(2011-05-10)
Chen, Che-Hao
;
Fuchs, Michael
;
應用數學系
;
Department of Applied Mathematics
The moment-transfer approach is a standard tool for deriving limit laws of sequences of random variables satisfying a distributional recurrence. However, so far the approach could not be applied to certain "one-sided" recurrences with slowly varying moments and normal limit law. In this paper, we propose a modified version of the moment-transfer approach which can be applied to such recurrences. Moreover, we demonstrate the usefulness of our approach by re-deriving several recent results in an almost automatic fashion.
Generation of optical crystals and quasicrystal beams: Kaleidoscopic patterns and phase singularity
(2011-05-10)
Chen, Y. F.
;
Liang, H. C.
;
Lin, Y. C.
;
Tzeng, Y. S.
;
Su, K. W.
We explore the feasibility of the generation of pseudonondiffracting optical beams related to crystal and quasicrystal structures. It is experimentally confirmed that optical crystal and quasicrystal beams can be remarkably generated with a collimated light to illuminate a high-precision mask with multiple apertures regularly distributed on a ring. We also found that exotic kaleidoscopic patterns can be exhibited with the high-order quasicrystal beams. More importantly, the structures of phase singularities in optical quasicrystal beams are manifested.
Femtosecond pulses cleaning by transient-grating process Kerr-optical media
(2011-05-10)
Liu, Jun
;
Okamura, Kotaro
;
Kida, Yuichiro
;
Kobayashi, Talcayoshi
;
電子物理學系
We use a transient-grating (TG) process in a Kerr bulk medium to clean a femtosecond laser pulse. Using the technique, the temporal contrast of the generated TO signal is improved by more than two orders of magnitude in comparison with the incident pulse in a 0.5-mm-thick fused silica plate. The laser spectrum is smoothed and broadened, and the pulse duration is shortened simultaneously. We expect to extend this technique to a clean pulse with broadband spectral bandwidth at a wide spectral range because it is a phase-matched process.
Nonequilibrium frequency-dependent noise through a quantum dot: A real-time functional renormalization group approach
(2011-05-10)
Moca, C. P.
;
Simon, P.
;
Chung, C. H.
;
Zarand, G.
;
電子物理學系
We construct a real time current-conserving functional renormalization group (RG) scheme on the Keldysh contour to study frequency-dependent transport and noise through a quantum dot in the local moment regime. We find that the current vertex develops a nontrivial nonlocal structure in time that is governed by a new set of RG equations. Solving these RG equations, we compute the complete frequency and temperature dependence of the noise spectrum. For voltages that are large compared to the Kondo temperature (i.e., eV >> k(B)T(K)), two sharp antiresonances are found in the noise spectrum at frequencies h omega = +/- eV and, correspondingly, two Kondo-assisted peaks appear in the ac conductance through the dot.
Microprobe array structure and method for manufacturing the same
(2011-05-10)
Chiou Jin-Chern
;
Hung Chen-Chun
;
Chang Chih-Wei
A microprobe array structure with self-stabilization capability and a method for manufacturing the same are proposed. The microprobe array structure is used to sense various biopotential signals, and is characterized in that the etching parameters are controlled during etching to manufacture a microprobe structure with a reduced bottom cross section so that the microprobe can be firmly stabilized in the skin tissue. Moreover, a conducting layer is formed on the microprobe to sense signals. A design of electric isolation between microprobes is also proposed. The microprobe array can therefore be used for the measurement of various biopotential signals, and can also be used as a stimulus.
Method and apparatus for decoding shortened BCH codes or reed-solomon codes
(2011-05-10)
Chang Hsie-Chia
;
Wu Jau-Yet
;
Liao Yen-Chin
The present invention proposes a method and apparatus for decoding BCH codes and Reed-Solomon codes, in which a modified Berlekamp-Massey algorithm is used to perform the decoding process and the efficiency of the decoder can be improved by re-defining the error locating polynomial as a reverse error locating polynomial, while the operation of the decoding process can be further realized by a common re-configurable module. Furthermore, the architecture of the decoder is consisted of a plurality of sets of re-configurable modules in order to provide parallel operations with different degrees of parallel so that the decoding speed requirement of the decoder in different applications can be satisfied.
Vertical transmission line structure that includes bump elements for flip-chip mounting
(2011-05-10)
Chang Edward Yi
;
Wu Wei-Cheng
;
Hwang Ruey-Bing
;
Hsu Li-Han
A vertical transmission structure for high frequency transmission lines includes a conductive axial core and a conductive structure surrounding the conductive axial core. The vertical transmission structure is applied to a high-frequency flip chip package for reducing the possibility of underfill from coming in contact with the conductive axial core.
Morphological Stabilization by In Situ Polymerization of Fullerene Derivatives Leading to Efficient, Thermally Stable Organic Photovoltaics
(2011-05-10)
Cheng, Yen-Ju
;
Hsieh, Chao-Hsiang
;
Li, Pei-Jung
;
Hsu, Chain-Shu
;
應用化學系
The successful design and synthesis of two styryl-functionalized fullerene derivatives, [6,6]-phenyl-C(61) -butyric acid styryl dendron ester (PCBSD) and [6,6]-phenyl-C 61 -butyric acid styryl ester (PCBS) is presented. The polymerizable PCBS or PCBSD materials are incorporated into a poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) blend to form an active layer of ternary blend. The blending systems are fi rst thermally annealed at 110 C for 10 min to induce optimal morphology, followed by heating at 150 C for 10 min to trigger the in situ polymerization of styrene groups. Through chemical crosslinking of PCBSD, the initial morphology of the blend (P3HT:PCBM:PCBSD = 6:5:1 in weight) can be effectively fi xed and stably preserved. The device based on this blend shows extremely stable device characteristics, delivering an average power conversion effi ciency (PCE) of 3.7% during long-term thermal treatment. By molecular engineering to reduce the insulating portion, PCBS with higher C 60 content (71 wt%) possesses better electron-transport properties than PCBSD (58 wt%). Encouragingly, at a low doping concentration of PCBS in the blend (P3HT:PCBM:PCBS = 6:5:1 in weight), linear-polymerized PCBS can stabilize the morphology against thermal heating. This device exhibits more balanced charge mobility to achieve an average PCE of 3.8% over 25 h heating at 150 degrees C.
Structure of polarizing terahertz wave device
(2011-05-10)
Chao Ru-Pin
;
Pan Ci-Ling
;
Hsieh Cho-Fan
;
Lai Yu-Chien
The Terahertz Polarizer structure of the present invention comprises of: A pair of parallel quartz layers for forming a rectangular cube with internal space, then a birefringent liquid crystal is placed in the internal space and sealed, and a pair of permanent magnets with reverse polarities are placed at both sides of the pair of fused silica layers.
大江健三郎：《死者的傲氣》─生與死的對談
(2011-05-11)
何資宜
;
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。
PRESSURE DETECTOR AND PRESSURE DETECTOR ARRAY
(2011-05-12)
Meng Hsin- Fei
;
Horng Sheng-Fu
;
Chao Yu-Chiang
;
Chen Chun-Yu
;
Lai Wei-Jen
A pressure detector is disclosed having an organic transistor, a pressure-detecting layer and a first electrode. The organic transistor includes an emitter, an organic layer, a grid formed with holes, and a collector, the organic layer being sandwiched between the emitter and the collector. The pressure-detecting layer is formed on the organic transistor such that the collector is sandwiched between the organic layer and the pressure-detecting layer. The first electrode is formed on the pressure-detecting layer such that the pressure-detecting layer is sandwiched between the collector and the first electrode. The area of the active region of the pressure detector is determined by the overlapped area of the electrodes, thereby reducing the pitch of the electrodes and thus the size of the pressure detector.
Identification of SEC61 beta and its autoantibody as biomarkers for colorectal cancer
(2011-05-12)
Fan, Chung-Wei
;
Chan, Chung-Chuan
;
Chen, Kuei-Tien
;
Twu, Jen
;
Huang, Ya-Shu
Background: To identify novel serological biomarkers for human colorectal cancer (CRC). we analyzed CRC tissues using gel-assisted digestion and isobaric tags with related and absolute quantitation (iTRAQ) labeling mass spectrometry (MS). By comparing pairs of tumor tissues and matched normal tissues. we discovered the SEC61 beta with expression changes 3.3-fold and a marginal statistical significance (p=0.052) previously. Methods: SEC61 beta expression in CRC tissues was further analyzed by western blotting and immunohistochemistry. We next assessed the putative diagnostic value of the SEC61 beta autoantibody as a serum marker. Results: Using western blotting analysis. SEC61 beta expression was increased 1.9-fold in tumor tissues. Immunohistochemical analysis of 64 CRC specimens showed that SEC61 beta was positively detected in 64% of the tumors, but weakly or not detected in > 80% of the adjacent nontumor epithelial cells. Western blot analysis with plasma samples showed that the sensitivity and specificity of the SEC61 beta autoantibody from patients with CRC were 79% and 75%. respectively. Importantly, the results of the SEC61 beta autoantibody for early detection of colorectal cancer revealed a higher sensitivity of 77% than the carcinoembryonic antigen (CEA) assay. Conclusions: Measurement of SEC61 beta autoantibody levels may provide an alternative detection indicator for CRC, particularly among early-stage patients. (C) 2011 Elsevier B.V. All rights reserved.
Subwavelength Antireflective Si Nanostructures Fabricated by Using the Self-Assembled Silver Metal-Nanomask
(2011-05-12)
Chang, Yuan-Ming
;
Shieh, Jiann
;
Juang, Jenh-Yih
;
電子物理學系
;
Department of Electrophysics
We report a lithography-free approach for fabricating silicon nanopillars (Si-NPs) and biomimetics porous silicon (P-Si) with excellent antireflective properties. The self-assembled silver nanostructures (nanoislands and disordered nanogrids) were formed via the Volmer-Weber (island growth) mode during the deposition process, which, in turn, serve as a metal-nanomask for the subsequent dry etching process carried out for fabricating the Si-NPs and P-Si on Si substrates. Reflectivity of about 0.65% was obtained over the spectral region ranging from deep-ultraviolet to infrared light (300-1000 nm). The remarkable antireflective characteristics obtained are attributed to the drastic decrease of effective index of refraction and the enhanced matching effect between air and substrate resulting from the Si nanostructures and suggesting an interesting alternative route for producing nanostructures that might be useful for photovoltaic applications.
Constructing independent spanning trees for locally twisted cubes
(2011-05-13)
Liu, Yi-Jiun
;
Lan, James K.
;
Chou, Well Y.
;
Chen, Chiuyuan
;
應用數學系
The independent spanning trees (ISTs) problem attempts to construct a set of pairwise independent spanning trees and it has numerous applications in networks such as data broadcasting, scattering and reliable communication protocols. The well-known ISTs conjecture, Vertex/Edge Conjecture, states that any n-connected/n-edge-connected graph has n vertex-ISTs/edge-ISTs rooted at an arbitrary vertex r. It has been shown that the Vertex Conjecture implies the Edge Conjecture. In this paper, we consider the independent spanning trees problem on the n-dimensional locally twisted cube LTQ(n). The very recent algorithm proposed by Hsieh and Tu (2009) [12] is designed to construct n edge-ISTs rooted at vertex 0 for LTQ(n). However, we find out that LTQ(n) is not vertex-transitive when n >= 4; therefore Hsieh and Tu's result does not solve the Edge Conjecture for LTQ(n),,. In this paper, we propose an algorithm for constructing n vertex-ISTs for LTQ(n); consequently, we confirm the Vertex Conjecture (and hence also the Edge Conjecture) for LTQ(n),. (C) 2011 Elsevier B.V. All rights reserved.