Browsing by Issue Date, starting with "2015-05-04"

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Multicomponent Reactions of Phosphines, Enynedioates and Cinnamaldimines Give gamma-Lactams with a 1,3,5-Hexatriene Moiety for Facile 6 pi Electrocyclization: Access to Oxindoles, Isatins and Isoxazolinones
(2015-05-04)
Deng, Jie-Cheng
;
Chen, Wu-Yin
;
Zhu, Chaoyuan
;
Chuang, Shih-Ching
;
應用化學系
Multicomponent reactions of phosphines, enynedioates and cinnamaldimines generated 3-phosphorus ylide gamma-lactams having a 1,3,5-hexatriene moiety with low activation energy barrier for 6 pi electrocyclization, through initial formation of 1,3-dipoles from the alpha(delta\')-Michael addition of phosphines to enynedioates. The reactive 1,3-dipoles underwent addition to cinnamaldimines, lactamization, 6 pi electrocyclization and oxidation to give 3-phosphorus ylide oxindoles as platform molecules toward isatins and isoxazolinones. The key step, 6 pi electrocyclization, was further examined by a kinetic and a computational study.
GaSb-based mid infrared photonic crystal surface emitting lasers
(2015-05-04)
Pan, Chien Hung
;
Lin, Chien Hung
;
Chang, Ting Yuan
;
Lu, Tien Chang
;
Lee, Chien Ping
We demonstrated for the first time above room temperature (RT) GaSb-based mid-infrared photonic crystal surface emitting lasers (PCSELs). The lasers, under optical pumping, emitted at lambda(lasing) similar to 2.3 mu m, had a temperature insensitive line width of 0.3nm, and a threshold power density (P-th) similar to 0.3KW/cm(2) at RT. Type-I InGaAsSb quantum wells were used as the active region, and the photonic crystal, a square lattice, was fabricated on the surface to provide optical feedback for laser operation and light coupling for surface emission. The PCSELs were operated at temperatures up to 350K with a small wavelength shift rate of 0.21 nm/K. The PCSELs with different air hole depth were studied. The effect of the etched depth on the laser performance was also investigated using numerical simulation based on the coupled-wave theory. Both the laser wavelength and the threshold power decrease as the depth of the PC becomes larger. The calculated results agree well with the experimental findings. (C) 2015 Optical Society of America
I help, therefore, I learn: service learning on Web 2.0 in an EFL speaking class
(2015-05-04)
Sun, Yu-Chih
;
Yang, Fang-Ying
;
英語教學研究所
;
Institute of Teaching English to speakers of other Languages
The present study integrates service learning into English as a Foreign Language (EFL) speaking class using Web 2.0 tools - YouTube and Facebook - as platforms. Fourteen undergraduate students participated in the study. The purpose of the service-learning project was to link service learning with oral communication training in an EFL speaking class by having each student create two YouTube videos in which they made informative presentations about the university (e.g., transportation system) and the city (e.g., sightseeing spots) in English to international students on campus. A Facebook community was established as a forum for students to share their videos with the international students and peers. The results suggest that the project enhanced EFL students\' public speaking-related skills (e.g., idea and content development, and pronunciation), built their confidence in speaking English, and allowed them to develop their own learning process and strategies. Moreover, Web 2.0 tools endow service learning with new possibilities of reaching a greater number of the target audience and provide the members of the community with alternative means of communication.
The multi-server retrial system with Bernoulli feedback and starting failures
(2015-05-04)
Yang, Dong-Yuh
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Ke, Jau-Chuan
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Wu, Chia-Huang
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工業工程與管理學系
;
Department of Industrial Engineering and Management
In this paper, we present a detailed analysis of a multi-server retrial queue with Bernoulli feedback, where the servers are subject to starting failures. Upon completion of a service, a customer would decide either to leave the system with probability p or to join the retrial orbit again for another service with complementary probability 1-p. We analyse this queueing system as a quasi-birth-death process. Specifically, the equilibrium condition of the system is given for the existence of the steady-state analysis. Applying the matrix-geometric method, the formulae for computing the rate matrix and stationary probabilities are obtained. We further develop the matrix-form expressions for various system performance measures. A cost model is constructed to determine the optimal number of servers, the optimal mean service rate and the optimal mean repair rate subject to the stability condition. Finally, we give a practical example to illustrate the potential applicability of this model.
Exploiting the image of the surface reflectivity to measure refractive index profiling for various optical fibers
(2015-05-04)
Weng, Chun-Jen
;
Hsu, Ken-Yuh
;
Chen, Yung-Fu
;
電子物理學系
;
光電工程學系
A direct image method of surface reflectivities on a cleaved fiber end with a filtered halogen lamp and a TE-cooled CCD with high dynamic range is proposed to measure the multi-wavelength refractive index profiling (RIP). A polished black glass is used to be a reference standard for measuring the absolute reflectivity of the fiber end. With the developed calibration procedures, both the spatially dependent sensitivity and spectral responsivity of the CCD pixels can be eliminated to achieve the high spatial accuracy. Tested fiber is connected with a fiber terminator to prevent errors from the backside return light. With the present method, the RIP can be precisely measured for not only multi-mode fibers but also single-mode fibers. (C) 2015 Optical Society of America
60-GHz optical/wireless MIMO system integrated with optical subcarrier multiplexing and 2x2 wireless communication
(2015-05-04)
Lin, Chi-Hsiang
;
Lin, Chun-Ting
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Huang, Hou-Tzu
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Zeng, Wei-Siang
;
Chiang, Shou-Chih
This paper proposes a 2x2 MIMO OFDM Radio-over-Fiber scheme based on optical subcarrier multiplexing and 60-GHz MIMO wireless transmission. We also schematically investigated the principle of optical subcarrier multiplexing, which is based on a dual-parallel Mach-Zehnder modulator (DP-MZM). In our simulation result, combining two MIMO OFDM signals to drive DP-MZM gives rise to the PAPR augmentation of less than 0.4 dB, which mitigates nonlinear distortion. Moreover, we applied a Levin-Campello bit-loading algorithm to compensate for the uneven frequency responses in the V-band. The resulting system achieves OFDM signal rates of 61.5-Gbits/s with BER of 10(-3) over 25-km SMF transmission followed by 3-m wireless transmission. (C) 2015 Optical Society of America
Suppressed ionic effect and low-frequency texture transitions in a cholesteric liquid crystal doped with graphene nanoplatelets
(2015-05-04)
Wu, Po-Chang
;
Lisetski, Longin N.
;
Lee, Wei
;
影像與生醫光電研究所
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Institute of Imaging and Biomedical Photonics
We focus on investigating the dielectric behaviors and the low-frequency texture transitions in a cholesteric liquid crystal (CLC) doped with graphene nanoplatelets (GNPs) by means of dielectric spectroscopy and measurements of electro-optical responses. The experimental results indicate that incorporating GNPs at a content of 0.5 wt% into the CLC leads to significant suppression of ionic behaviors, as manifested by the reduction in ionic density, diffusivity, and relaxation frequency. In addition, the electro-optical properties of the GNP-doped CLC cell show the lowered operation voltage for the switching from the planar to focal conic state and the absence of the low-frequency focal-conic-to-uniform-lying-helix texture transition. Such results are attributable to the effects of GNPs as nuclei in the CLC medium, giving rise to the repression of the ionic and electrohydrodynamic effects. (C) 2015 Optical Society of America
Embedded system using image coding method
(2015-05-05)
Wu Bing-Fei
;
Chen Yen-Lin
;
Huang Hao-Yu
An image coding method including constructing a plurality of edge models with a Forward Discrete Cosine Transform (FDCT) algorithm; creating adjustment equations each matching one of the edge models; capturing an image comprising pixels; selecting the pixels of the image to define image blocks; detecting by block-edge detection (BED) a pattern collectively exhibited by the pixels in the each of the image blocks and then comparing the detected pattern with patterns of the edge models; changing the patterns of the image blocks to the patterns of the edge models and adjusting the dominating coefficient by the adjustment factor after determining that the patterns of the image blocks approximate to the patterns of the edge models; and performing a coding process on the edge models by LLEC to generate a compressed image corresponding to the edge models. An embedded system is applicable to the image coding method.
交大e-News第185期-蘭花屋升級版與台積電共創竹科教育綠園區
(2015-05-05)
國立交通大學秘書室
;
Secretariat
Cosmological birefringence due to CPT-even Chern-Simons-like term with Kalb-Ramond and scalar fields
(2015-05-05)
Ho, Shih-Hao
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Kao, W. F.
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Bamba, Kazuharu
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Geng, C. Q.
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物理研究所
We study the CPT-even dimension-six Chern-Simons-like term by including dynamical Kalb-Ramond and scalar fields to examine the cosmological birefringence. We show that the combined effect of a neutrino current and a Kalb-Ramond field could induce a sizable rotation polarization angle in the cosmic microwave background radiation polarization.
Low Cost Facile Synthesis of Large-Area Cobalt Hydroxide Nanorods with Remarkable Pseudocapacitance
(2015-05-06)
Deng, Ming-Jay
;
Song, Cheng-Zhao
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Wang, Chien-Chia
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Tseng, Yuan-Chieh
;
Chen, Jin-Ming
Large-area Co(OH)(2)-based supercapacitor electrodes composed of nanotube arrays grown on a 3D nickel-foam (CONTA) electrode and sucker-like nanoporous films grown on a 3D nickel-foam (COSNP) electrode were prepared with a facile electrochemical method for applications in energy storage. These nanoporous Co(OH)(2) electrodes were fabricated with the codeposition of Cu/Ni film on the nickel foam, then etching of Cu from the Cu/Ni layer to form Ni nanotube arrays and sucker-like Ni nanoporous layers, and further cathodic deposition of Co(OH)(2) on the prepared nanoporous Ni substrates. The CONTA and COSNP electrodes exhibited specific capacitances of 2500 and 2900 F/g in a voltage range of 0.65 V (capacitance of the substrates deducted from the total) at 1 A/g in a three electrode cell, respectively. The COSNP electrode demonstrated an excellent supercapacitive performance with specific capacitances 1100 F/g at 1 A/g and 850 F/g at 20 A/g in a voltage range of 1.2 V in a two electrode cell. The remarkable performance of COSNP electrodes correlated with a large conversion of the Co oxidation state during the charge/discharge cycling were examined by in situ X-ray absorption near edge structure (XANES).
Size effect on multiferroic TbMn2O5 nanorods
(2015-05-07)
Yang, Chun-Chuen
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Tung, Yung-Hsiang
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Chen, Yi-Jung
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Hsu, Ting-Wei
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You, Pang-Yen
The effect of the size of TbMn2O5 on their magnetoelectric properties is studied using a field emission transmission electron microscope, ac magnetic susceptibility, relative dielectric constant, specific heat capacity, and x-ray diffraction at various temperatures. A bulk sample and nanorods with two axial lengths, < L-C >, are investigated. Nanorods with < L-C > of 216 nm and 64 nm crystallize with orthorhombic Pbam symmetry as the bulk material. The axial direction of the two sizes of nanorod is parallel to the c axis of the crystal. No particular radial direction is observed. The critical size for the magnetic ordering of TbMn2O5 is found to be between < L-C > - 64 nm and 216 nm. Experiments on specific heat capacity verified these results. No similar phenomenon concerning the ferroelectric property is observed. At T = 30K and 35 K, the < L-C > - 216 nm sample yields a charge-ordering-like x-ray diffraction peak, which may be associated with the magnetically induced charge ordering superlattice. (C) 2015 AIP Publishing LLC.
BROADBAND CONNECTION STRUCTURE AND METHOD
(2015-05-07)
Li Chun-Hsing
;
Kuo Chien-Nan
A broadband connection structure is disclosed. The broadband connection structure includes a carrier and a chip. The carrier includes a first resonator. The chip includes a second resonator and configured on the carrier using a flip-chip method. The first resonator is connected to the second resonator via a magnetic field and an electric field existing therebetween to transmit a broadband signal between the carrier and the chip. A broadband connection method is also disclosed.
Magnetic tunnel junction based out-of-plane field sensor with perpendicular magnetic anisotropy in reference layer
(2015-05-07)
Lee, Y. C.
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Chao, C. T.
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Li, L. C.
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Suen, Y. W.
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Horng, Lance
A magnetic tunnel junction (MTJ) with orthogonal magnetic anisotropy and consisting of Ta X/Co40Fe40B20 1.2 (reference)/MgO 2.0/Co20Fe60B20 2.3 (sensing)/Ta 5/Ru 5 (thickness in nanometers), where X ranges from 15 to 30, is proposed and investigated in response to the demand for out-of-plane field sensors. The reference layer with perpendicular magnetic anisotropy (PMA) demonstrates tuneable coercivity ranging from 72 Oe to 175 Oe. The sensing layer exhibits in-plane anisotropy with the avoidance of exchange coupling from the PMA reference layer because of a thick MgO barrier layer. The magnetization reversal behavior of micron scale devices not only corresponds well to the sheet film, but is also independent in terms of shape and size. The magnetoresistance curve exhibits a ratio of similar to 27% in the presence of a perpendicular field and is insensitive to the in-plane field. For perpendicular field sensing, the dynamic range with a sensitivity of similar to 0.3%/Oe can achieve +/- 25 Oe with a coercive field of less than 3 Oe. Additionally, even when bias is applied up to 9.1 mV, magnetic fluctuation still stays below 0.15 mOe. (C) 2015 AIP Publishing LLC.
Characterization and Modeling of Nonfilamentary Ta/TaOx/TiO2/Ti Analog Synaptic Device
(2015-05-08)
Wang, Yu-Fen
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Lin, Yen-Chuan
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Wang, I-Ting
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Lin, Tzu-Ping
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Hou, Tuo-Hung
A two-terminal analog synaptic device that precisely emulates biological synaptic features is expected to be a critical component for future hardware-based neuromorphic computing. Typical synaptic devices based on filamentary resistive switching face severe limitations on the implementation of concurrent inhibitory and excitatory synapses with low conductance and state fluctuation. For overcoming these limitations, we propose a Ta/TaOx/TiO2/Ti device with superior analog synaptic features. A physical simulation based on the homogeneous (nonfilamentary) barrier modulation induced by oxygen ion migration accurately reproduces various DC and AC evolutions of synaptic states, including the spike-timing-dependent plasticity and paired-pulse facilitation. Furthermore, a physics-based compact model for facilitating circuit-level design is proposed on the basis of the general definition of memristor devices. This comprehensive experimental and theoretical study of the promising electronic synapse can facilitate realizing large-scale neuromorphic systems.
剛柔並濟　來自近畿之聲
(2015-05-10)
張婷芳
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Department of Communication and Technology
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傳播與科技學系
近畿小子為傑尼斯旗下雙人演唱組合，曲風為抒情走向，與兩人迥異的聲線搭配，踏出別於主流偶像的音樂道路。
建設纜車　找出核心價值
(2015-05-10)
陳思寧
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Department of Communication and Technology
;
傳播與科技學系
臺灣目前共有兩條營運中及九條規劃中的纜車線道，先前北投纜車確定停止策畫，掀起纜車建設的隱憂。
國片票房　誰來買單
(2015-05-10)
沈祖廷
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Department of Communication and Technology
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傳播與科技學系
分析近九年的國片產量和總票房的關係，並深入電影票房和預算資金比值的探討，尋求國片票房提升的解決之道。
人為的迫害　石虎絕種危機
(2015-05-10)
王彥琪
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Department of Communication and Technology
;
傳播與科技學系
臺灣目前唯一野生貓科動物石虎，數量剩不到五百隻。根據研究，造成石虎滅絕的主要因素為人類所帶來的迫害。
臺灣合唱　邁進與希望　
(2015-05-10)
包金
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Department of Communication and Technology
;
傳播與科技學系
臺灣合唱團，或許在很多方面都遇到瓶頸，但經過許多人努力，往更新的未來展望。