Browsing by Issue Date, starting with "2012-02-25"

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Seismic spectral acceleration assessment of masonry in-filled reinforced concrete buildings by a coefficient-based method
(2012-02-25)
Su, R. K. L.
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Lee, C. L.
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Wang, Y. P.
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土木工程學系
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Department of Civil Engineering
This study explores a coefficient-based seismic capacity assessment method with a special emphasis on low-rise masonry in-filled (MI) reinforced concrete (RC) buildings subjected to earthquake motion. The coefficient-based method without requiring any complicated finite element analysis is a simplified procedure to assess the maximum spectral acceleration capacity of buildings. This paper first compares the fundamental periods of MI RC structures obtained, respectively, from experimental period data and empirical period-height formulas. The coefficient-based method for low-rise masonry buildings is then calibrated by the published experimental results obtained from shaking table tests. The comparison of the experimental and estimated results indicates that the simplified coefficient-based method can provide good approximations of the maximum spectral accelerations at peak loads of the low-rise masonry reinforced concrete buildings if a proper set of drift factors and initial fundamental vibration periods of structures are used.
Annealing Effect on Electrospun Polymer Fibers and Their Transformation into Polymer Microspheres
(2012-02-27)
Fan, Ping-Wen
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Chen, Wan-Ling
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Lee, Ting-Hsien
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Chen, Jiun-Tai
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應用化學系
Electrospinning is a simple and convenient technique to produce polymer fibers with diameters ranging from several nanometers to a few micrometers. Different types of polymer fibers have been prepared by electrospinning for various applications. Among different post-treatment methods of electrospun polymer fibers, the annealing process plays a critical role in controlling the fiber properties. The morphology changes of electrospun polymer fibers under annealing, however, have been little studied. Here we investigate the annealing effect of electrospun poly(methyl methacrylate) (PMMA) fibers and their transformation into PMMA microspheres. PMMA fibers with an average size of 2.39 mu m are first prepared by electrospinning a 35 wt% PMMA solution in dimethylformamide. After the electrospun fibers are thermally annealed in ethylene glycol, a non-solvent for PMMA, the surfaces of the fibers undulate and transform into microspheres driven by the Rayleigh instability. The driving force of the transformation process is the minimization of the interfacial energy between the polymer fibers and ethylene glycol. The sizes of the microspheres fit well with the theoretical predictions. Longer annealing times are found to be required at lower temperatures to obtain the microspheres.
Orthogonally polarized dual-wavelength Nd:LuVO4 laser at 1086 nm and 1089 nm
(2012-02-27)
Huang, Y. P.
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Cho, C. Y.
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Huang, Y. J.
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Chen, Y. F.
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電子物理學系
A comparison between the fluorescence spectra of the Nd-doped vanadate crystals (Nd:YVO4, Nd:GdVO4, Nd:LuVO4) for the F-4(3/2) -> I-4(11/2) transition is studied. We numerically analyze the condition of gain-to-loss balance via an uncoated intracavity etalon to achieve the dual-wavelength operation. We further experimentally demonstrate the orthogonally polarized dual-wavelength laser with a single Nd:LuVO4 crystal. The simultaneous dual-wavelength Nd:LuVO4 laser at 1085.7 nm in sigma polarization and 1088.5 nm in pi polarization is realized. At an incident pump power of 12 W, the average output power obtained at 1085.7 nm and 1088.5 nm is 0.4 W and 1.7 W, respectively. (c) 2012 Optical Society of America
Two-step photoionization of trans-stilbene in acetonitrile via an ion-pair precursor studied with picosecond time-resolved absorption and Raman spectroscopies
(2012-02-27)
Miki, Hiroko
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Yoshida, Kyousuke
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Kawate, Chieko
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Shimada, Rintaro
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Takaya, Tomohisa
Picosecond time-resolved visible absorption and Raman spectra of trans-stilbene in acetonitrile have been measured. A new transient absorption band is observed at 440 nm, whose decay time constant coincides with that of the rise of the radical cation. In addition to the known Raman bands of the radical cation, a new Raman feature showing a fast decay is found at 1599 cm(-1). We assign the 440 nm absorption band and the 1599 cm(-1) Raman band to a precursor of the radical cation. The precursor may well be an ion pair that holds an ejected electron still around the cation. (C) 2012 Elsevier B. V. All rights reserved.
Room temperature polariton lasing vs. photon lasing in a ZnO-based hybrid microcavity
(2012-02-27)
Lu, Tien-Chang
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Lai, Ying-Yu
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Lan, Yu-Pin
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Huang, Si-Wei
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Chen, Jun-Rong
We report on the room temperature polariton lasing and photon lasing in a ZnO-based hybrid microcavity under optical pumping. A series of experimental studies of the polariton lasing (exciton-photon detunings of delta = -119meV) in the strong-coupling regime are discussed and compared to a photon lasing (delta = -45meV) in the weak-coupling regime obtained in the same structure. The measured threshold power density (31.8kW/cm(2)) of polariton lasing is one order of magnitude lower than that of the photon lasing (318.2kW/cm(2)). In addition, the comparison between polariton lasing and photon lasing is done in terms of the linewidth broadening, blue-shift of the emission peak, and polarization. (C) 2012 Optical Society of America
Optimal Te-doping in GaSe for non-linear applications
(2012-02-27)
Ku, Shin An
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Chu, Wei-Chen
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Luo, Chih Wei
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Andreev, Yu. M.
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Lanskii, Grigory
Centimeter-sized Te-doped GaSe ingots were grown from the charge compositions of GaSe with nominals 0.05, 0.1, 0.5, 1, and 3 mass% Te, which were identified as e -GaSe: Te (0.01, 0.07, 0.38, 0.67, and 2.07 mass%) single crystals. The evolution of the absorption peaks of the phonon modes E'((2)) (similar to 0.584 THz) and E"((2)) (1.77 THz) on Te-doping in GaSe: Te crystals was studied by THz time-domain spectroscopy. This study proposes that the evolution of both E'((2)) and E"((2)) absorption peaks correlates well with the optical quality of Te-doped GaSe crystals, which was confirmed by experimental results on the efficiency of THz generation by optical rectification. Maximal intensity of the absorption peak of the rigid layer mode E'((2)) is proposed as a criterion for identification of optimal Te-doping in GaSe crystals. (C) 2012 Optical Society of America
Compact camera module testing equipment with a conversion lens
(2012-02-27)
Pan, Jui-Wen
;
光電系統研究所
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生醫電子轉譯研究中心
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Institute of Photonic System
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Biomedical Electronics Translational Research Center
Modified testing equipment for adjusting the back focal length of a compact camera module (CCM) is proposed. The advantages of this modified testing equipment which includes a conversion lens are that it saves on testing space, offers a smaller sized testing chart, as well as high speed chart changing, and variable object distances. The modified testing equipment can produce a test chart of 38.32 mm compared to an equivalent testing chart of 5000 mm with the conventional testing equipment. At the regular object distance of 2000 mm, both total track and testing chart size for the modified test equipment were 8.3% that of the conventional testing equipment. By using this testing equipment, the testing space can be shrunk significantly. (C) 2012 Optical Society of America
Direct observation of denitrogenation process of 2,3-diazabicyclo[2.2.1]hept-2-ene (DBH) derivatives, using a visible 5-fs pulse laser
(2012-02-27)
Abe, Manabu
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Iwakura, Izumi
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Yabushita, Atushi
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Yagi, Shingo
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Liu, Jun
The mechanism of denitrogenation for 2,3-diazabicyclo[2.2.1]hept-2-ene (DBH) derivatives was investigated using a visible 5-fs pulse laser. The time-dependent wavenumber changes observed in this study revealed that the concerted denitrogenation occurs in the parent DBH. However, a stepwise denitrogenation mechanism was found for the 7,7-diethoxy-substituted DBH derivative. (C) 2012 Elsevier B. V. All rights reserved.
Gate-all-around polycrystalline-silicon thin-film transistors with self-aligned grain-growth nanowire channels
(2012-02-27)
Liao, Ta-Chuan
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Kang, Tsung-Kuei
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Lin, Chia-Min
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Wu, Chun-Yu
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Cheng, Huang-Chung
In this letter, gate-all-around (GAA) polycrystalline silicon thin-film transistors (TFTs) with self-aligned grain-growth channels were fabricated using excimer laser crystallization (ELC) on a recessed-nanowire (RN) structure. Via the RN structure constructed by a simple sidewall-spacer formation, location-controlled nucleation and volume-confined lateral grain growth within the RN body during ELC process have been demonstrated with only one perpendicular grain boundary in each nanowire channel. Because of the high-crystallinity channel together with GAA operation mode, the proposed GAA-RN TFTs show good device integrity of lower threshold voltage, steeper subthreshold slope, and higher field-effect mobility as compared with the conventional planar counterparts. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3691184]
Method of detecting moving object
(2012-02-28)
Lin Daw-Tung
;
Liu Li-Wei
Proposed is a method of detecting a moving object, including: providing an image-set at least including a first image and a second image correlated in a time series, the first image preceding the second image; defining a detecting region and a detecting direction so as to construct a virtual gate in the first image; estimating the motion vector in a time series; comparing, by the virtual gate, the second image with the first image so as to determine a difference therebetween in terms of an object's position and motion vector; and retrieving the object to be an effective moving object upon determination of the object as lying within the detecting region defined in the virtual gate and moving in a direction substantively the same with the detecting direction. This invention presents a moving object detection method without the need to construct a background model a priori.
Charge pump
(2012-02-28)
Wu Chun-Yi
;
Hsieh Wei-Chih
;
Chang Ming-Hung
;
Hwang Wei
A charge pump is disclosed for amplifying an input voltage received at an input end and outputting the amplified voltage at an output end as an output voltage. The charge pump includes a plurality of source/drain coupling transistors for serving as charging capacitors, and a plurality of cascode-connected transistors being symmetrically connected to between the input end and the output end. The charge pump further includes a plurality of diode-connected transistors to protect the source/drain coupling transistors against breakdown during the course of charge transfer and to speed up the charge transfer.
TWO NEW SANDPERCHES (PERCIFORMES: PINGUIPEDIDAE: PARAPERCIS) FROM SOUTH CHINA SEA, BASED ON MORPHOLOGY AND DNA BARCODING
(2012-02-29)
Ho, Hsuan-Ching
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Chang, Chia-Hao
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Shao, Kwang-Tsao
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生物科技學系
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Department of Biological Science and Technology
Two new cryptic sandperch species of the pinguipedid genus Parapercis are described from off southern Taiwan, northern South China Sea. Parapercis kentingensis n. sp., described from 25 specimens, is morphologically similar to P shaoi Randall, 2008. Parapercis rubromaculata n. sp., described from four specimens, is morphologically similar to P randalli Ho & Shao, 2010. The four species have sympatric distributions in southern Taiwan. Both new species differ from their congeners in colouration and a combination of other characters. Morphological evidence for establishing new species status is also supported by DNA barcoding.
Structural and morphological transformations of TiO2 nanotube arrays induced by excimer laser treatment
(2012-02-29)
Hsu, Ming-Yi
;
Nguyen Van Thang
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Wang, Chih
;
Leu, Jihperng
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材料科學與工程學系
The structural and morphological transformations of TiO2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400 degrees C for 1 h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25 ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85 degrees was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs. (c) 2011 Elsevier B.V. All rights reserved.
Core Site-Moiety Maps Reveal Inhibitors and Binding Mechanisms of Orthologous Proteins by Screening Compound Libraries
(2012-02-29)
Hsu, Kai-Cheng
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Cheng, Wen-Chi
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Chen, Yen-Fu
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Wang, Hung-Jung
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Li, Ling-Ting
Members of protein families often share conserved structural subsites for interaction with chemically similar moieties despite low sequence identity. We propose a core site-moiety map of multiple proteins (called CoreSiMMap) to discover inhibitors and mechanisms by profiling subsite-moiety interactions of immense screening compounds. The consensus anchor, the subsite-moiety interactions with statistical significance, of a CoreSiMMap can be regarded as a "hot spot" that represents the conserved binding environments involved in biological functions. Here, we derive the CoreSiMMap with six consensus anchors and identify six inhibitors (IC50 < 8.0 mu M) of shikimate kinases (SKs) of Mycobacterium tuberculosis and Helicobacter pylori from the NCI database (236,962 compounds). Studies of site-directed mutagenesis and analogues reveal that these conserved interacting residues and moieties contribute to pocket-moiety interaction spots and biological functions. These results reveal that our multi-target screening strategy and the CoreSiMMap can increase the accuracy of screening in the identification of novel inhibitors and subsite-moiety environments for elucidating the binding mechanisms of targets.
A junctionless SONOS nonvolatile memory device constructed with in situ-doped polycrystalline silicon nanowires
(2012-02-29)
Su, Chun-Jung
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Su, Tuan-Kai
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Tsai, Tzu-I
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Lin, Horng-Chih
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Huang, Tiao-Yuan
In this paper, a silicon-oxide-nitride-silicon nonvolatile memory constructed on an n(+)-poly-Si nanowire [NW] structure featuring a junctionless [JL] configuration is presented. The JL structure is fulfilled by employing only one in situ heavily phosphorous-doped poly-Si layer to simultaneously serve as source/drain regions and NW channels, thus greatly simplifying the manufacturing process and alleviating the requirement of precise control of the doping profile. Owing to the higher carrier concentration in the channel, the developed JL NW device exhibits significantly enhanced programming speed and larger memory window than its counterpart with conventional undoped-NW-channel. Moreover, it also displays acceptable erase and data retention properties. Hence, the desirable memory characteristics along with the much simplified fabrication process make the JL NW memory structure a promising candidate for future system-on-panel and three-dimensional ultrahigh density memory applications.
Characterizations and thermal stability improvement of phase-change memory device containing Ce-doped GeSbTe films
(2012-02-29)
Huang, Yu-Jen
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Tsai, Min-Chuan
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Wang, Chiung-Hsin
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Hsieh, Tsung-Eong
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材料科學與工程學系
Phase-transition temperature of GeSbTe (GST) chalcogenide film was drastically increased from 159 to 236 degrees C by cerium (Ce) doping (up to 8.6 at.%) without altering the resistivity property of GST. Grain refinement via the solid-solution mechanism and the amplification of p-type semiconducting behavior in Ce-doped GST were observed. They were correlated with the enhancement of thermal stability and data retention property of GST as revealed by exothermal and isothermal analyses. Phase-change memory (PCM) device characterized at various temperatures revealed an effective thermal stability improvement on the threshold voltage of PCM device by Ce doping. (c) 2011 Elsevier B.V. All rights reserved.
Dummy-Based Schemes for Protecting Movement Trajectories
(2012-03-01)
Lei, Po-Ruey
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Peng, Wen-Chih
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Su, Ing-Jiunn
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Chang, Chien-Ping
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資訊工程學系
Dummy-based anonymization techniques for protecting the location privacy of mobile users have appeared in the literature. By generating dummies that move in human-like trajectories, this approach shows that the location privacy of mobile users can be preserved. However, the trajectories of mobile users can still be exposed by monitoring the long-term movement patterns of users. We argue that, once the trajectory of a user is identified, the locations of the user are exposed. Thus, it is critical to protect the movement trajectories of mobile users in order to preserve user location privacy. We propose two schemes that generate consistent movement patterns in the long run. Guided by three parameters in a user specified privacy profile, namely, short-term disclosure, long-term disclosure and distance deviation, the proposed schemes derive movement trajectories for dummies. The experimental results show that our proposed schemes are more effective than existing works in protecting movement trajectories.
Glass biochip fabrication by laser micromachining and glass-molding process
(2012-03-01)
Huang, Chien-Yao
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Kuo, Chao-Hui
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Hsiao, Wen-Tse
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Huang, Kuo-Cheng
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Tseng, Shih-Feng
Due to their low cost, small size, and high-speed performance, biochips are often used in various bio-experiments. Compared with polymer-based biochips, glass-based substrates are less sensitive to heat and organic environments. This study presents a hybrid processing approach that uses laser micromachining (LMM) and precision glass molding (PGM) techniques to mass-produce glass-based biochips. A silicon carbide (SiC) mold with an outside diameter of 20 mm was used to hot emboss biochip channels measuring 200 mu m wide and 185 mu m deep. This study also identifies the optimal conditions for glass molding when processing soda-lime glass for biochip applications, and discusses the influence of the major processing parameters on biochip channel depth. This study uses the Taguchi method to assess the effects of several molding parameters on larger-the-better performance characteristics. The experiments in this study consider the effects of several molding parameters, such as molding temperature, pressing force, moving speed, temperature holding time, and vacuum environment, to achieve optimum characteristics for biochip channels. Orthogonal array analysis indicates that the optimal process parameters includes a 620 degrees C molding temperature, 1 kN pressing force, 5 mm/min moving speed, 60s temperature holding time, and a vacuum-free environment. This study also investigates the surface roughness of glass biochip channels. (C) 2011 Elsevier B.V. All rights reserved.
Managerial efficiency in Taiwan bank branches: A network DEA
(2012-03-01)
Yang, Chyan
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Liu, Hsian-Ming
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經營管理研究所
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Institute of Business and Management
Taiwan's banking industry remains highly fragmented and competitive after a series of financial liberalization and restructuring. With the enforcement of these fiscal policies, domestic banking institutions face a more dynamic, increasingly intense and highly competitive environment even as the banking industry's overall efficiency has gradually been enhanced. This structural change has further forced individual banking institutions, especially state-owned banks, to inspect the performance of their branches and identify improvement directions so as to gain further competitive advantages. To conduct a valid, fair and reliable evaluation on Taiwan's bank branches, we integrate a two-stage series performance model and fuzzy multiobjective model. A new scheme that considers the complementation of production and intermediation activities within a branch and overcomes the shortage of the traditional network DEA methodology about DMUs cannot be assessed on a common base. The results indicate that the overall performances of mixed ownership bank branches are superior to those of state-owned bank branches, representing that the advantages of banking privatization have some remedial effects for improving the managerial inefficiency of state-owned banks. In addition, the sensitivity analysis and decision-making matrix herein help bank management to identify branches' efficiency, weakness, and directions for improvement. (C) 2011 Elsevier B.V. All rights reserved.
Theory of infrared-dressed atomic photoionization by extremely ultraviolet attosecond pulse trains
(2012-03-01)
Lee, Han Chieh
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Da Jheng, Shih
;
Jiang, Tsin Fu
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物理研究所
;
Institute of Physics
We theoretically study the infrared (IR)-dressed photoionization of atoms excited by extreme ultraviolet attosecond pulse trains above ionization threshold. The initial state of atoms is treated perturbatively by the IR field, and the continuum states are considered as Coulomb-Volkov (CV) waves. CV waves can much reduce the gauge difference calculated with Volkov waves, and, in general, the contribution of ground-state perturbation to the photoelectron spectrum is negligible. Our calculations show qualitative agreement with the experimental results [Phys. Rev. Lett. 95, 013001 (2005)]. An evident dependence of the photoelectron spectrum on the delay phase between the IR field and the attosecond pulse train is exhibited in both helium and argon. The angular distribution of photoelectrons with various IR polarizations and the corresponding photoelectron spectra are presented. The linearly polarized IR fields are shown to have a higher controlling capability of the spectrum via IR delay phases than the circularly polarized fields. On the other hand, the circularly polarized IR fields have a fruitful angular dependence of photoelectrons with various IR delay phases. (C) 2012 Optical Society of America