Browsing by Issue Date, starting with "2009-01-22"

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PHOSPHORS AND LIGHTING APPARATUS USING THE SAME
(2009-01-22)
Chen, Teng-Ming
;
Tai, Hsiao-Ping
A phosphor has a chemical formula of: Am(Ba1-xEux)nPyOz, wherein A is at least one of the group consisting of Li, Na and K, while 0
LIGHT-EMITTING DEVICE AND METHOD FOR MAKING THE SAME
(2009-01-22)
CHIU, Ching-Hua
;
HUANG, Hung-Wen
;
KUO, Hao-Chung
;
LU, Tien-Chang
;
WANG, Shing-Chung
A light-emitting device is capable of emitting a light having a wavelength ranging from 300 to 550 nm, and includes: a substrate; a p-type semiconductor layer disposed on the substrate; an active layer disposed on the p-type semiconductor layer; a n-type semiconductor layer disposed on the active layer and having a waveguide-disposing surface; and a waveguide structure formed on the waveguide-disposing surface of the n-type semiconductor layer and having a plurality of spaced apart nanorods extending from the waveguide-disposing surface.
Single-layer triplet white polymer light-emitting diodes incorporating polymer oxides: Effect of charge trapping at phosphorescent dopants
(2009-01-26)
Chen, Fang-Chung
;
Chien, Shang-Chieh
;
Chen, Yung-Shiuan
;
光電工程學系
;
顯示科技研究所
This paper describes the effects of charge trapping on the device performances of triplet polymer light-emitting diodes (PLEDs) after the cathode contact had been improved through the blending of poly(ethylene glycol) (PEG) into the active layer. The external quantum efficiency (EQE) was enhanced when the dopant tended to trap electrons. In contrast, we observed no EQE enhancement for the device featuring a hole-trapping dopant. Because PEG promoted electron injection, more electrons were trapped in the triplet molecules, thereby enhancing the probability of recombination. Finally, after incorporating PEG, we further achieved white PLEDs exhibiting both high EQE and high power efficiency.
Room temperature negative differential resistance in DNA-based molecular devices
(2009-01-26)
Jangjian, Peng-Chung
;
Liu, Tzeng-Feng
;
Li, Mei-Yi
;
Tsai, Ming-Shih
;
Chang, Chia-Ching
A molecular device fabricated from metallic deoxyribonucleic acid (M-DNA) exhibits a negative differential resistance (NDR) behavior. When two gold electrodes were connected by Ni(2+)-chelated DNA, which was converted from lambda-DNA, not only was the conductivity of DNA improved, but a NDR device was formed as a full cyclic voltage sweep was applied to measure its current versus voltage characteristics at room temperature and in an ambient environment. Such electronic characteristics of a M-DNA device may have been caused by the redox reactions of Ni ions. This finding provides a simple way to construct electrical nanodevices from biological molecules.
Bonding anisotropy in multiferroic TbMnO3 probed by polarization dependent x-ray absorption spectroscopy
(2009-01-26)
Chen, J. M.
;
Lee, J. M.
;
Chen, C. K.
;
Chou, T. L.
;
Lu, K. T.
O K- and Mn L-2,L-3-edges x-ray absorption spectra of orthorhombic TbMnO3 single crystals show strong polarization dependence, in contrast with results of previous experiments on orthorhombic LaMnO3 and DyMnO3 thin films that show nearly isotropic spectral structure. First-principles calculations reveal that TbMnO3 exhibits a zigzag e(g) orbital ordering ground state. The highly distorted MnO6 octahedron and orbital ordering in TbMnO3 produce highly anisotropic Mn-O bonding within the ab plane, a frustration of the magnetic ordering, and the formation of complicated incommensurate magnetic structures.
Fabrication and characterization of three-dimensional all metallic photonic crystals for near infrared applications
(2009-01-26)
Yang, Yu-Lin
;
Hou, Fu-Ju
;
Wu, Shich-Chuan
;
Huang, Wen-Hsien
;
Lai, Ming-Chih
Three-dimensional all metallic photonic crystals with a feature size of 0.20 mu m were fabricated using electron-beam lithography with the photoresist of hydrogen silesquioxane. This process method has high compatibility with the fabrication of damascene copper interconnections and also simplifies the whole process flow. The dependence of the complete photonic band gaps on polarization was experimentally observed and compared with the simulation results. The band edge for the four-layer lattice was found at a wavelength of around 0.80 mu m in normal incidence.
Bonding anisotropy in multiferroic TbMnO(3) probed by polarization dependent x-ray absorption spectroscopy
(2009-01-26)
Chen, J. M.
;
Lee, J. M.
;
Chen, C. K.
;
Chou, T. L.
;
Lu, K. T.
O K- and Mn L(2,3)-edges x-ray absorption spectra of orthorhombic TbMnO(3) single crystals show strong polarization dependence, in contrast with results of previous experiments on orthorhombic LaMnO(3) and DyMnO(3) thin films that show nearly isotropic spectral structure. First-principles calculations reveal that TbMnO(3) exhibits a zigzag e(g) orbital ordering ground state. The highly distorted MnO(6) octahedron and orbital ordering in TbMnO(3) produce highly anisotropic Mn-O bonding within the ab plane, a frustration of the magnetic ordering, and the formation of complicated incommensurate magnetic structures.
Non-Condon vibronic coupling of coherent molecular vibration in MEH-PPV induced by a visible few-cycle pulse laser
(2009-01-26)
Kobayashi, Takayoshi
;
Zhang, Jun
;
Wang, Zhuan
;
電子物理學系
;
Department of Electrophysics
Vibrational real-time spectra of poly-[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH- PPV) were measured in a 5 fs pump-probe experiment simultaneously at 128 probe wavelengths with a multi-channel detection system. The spectral dependence of the coherent vibrational amplitudes obtained from the Fourier transform (FT) on the probe wavelength detected was found to be given by the sum of the ground-state absorption spectrum and its first and second derivatives. This indicates that the change of the transition probability caused by a wave packet motion can be explained as induced by both the non-Condon effect (non-Condon (NC) mechanism) and the time-dependent Franck-Condon factor (Frank-Condon (FC) mechanism). The FC mechanism can contribute to the first and second derivatives' dependence. On the other hand, the NC mechanism is dominant in the zeroth-order derivative. This result proves that the 1(1)B(u) exciton is strongly coupled with the excited (1)A(g) state, which is known to be essential in third-order optical nonlinearity. The amounts of shift of the absorption peaks and changes in the bandwidth due to the wave packet motions were determined for the four most prominent modes in the FT power spectra. The shift due to the FC mechanism was about 1.3-1.1% of the peak transition energy and the broadening of the vibronic transition due to the NC mechanism was about 8.0-7.6% of the bandwidth for the four modes. A novel ultrafast optical switch utilizing the modulation of electronic transition probability by molecular vibration through vibronic coupling and the interference of the wave packets is proposed.
Tunable terahertz wavelength selector device using magnetically controlled birefringence of liquid crystals
(2009-01-27)
Chao
;
Ru-Pin
;
Pan
;
Ci-Ling
;
Chen
The present invention provides a tunable terahertz (THz) wavelength selector device, which includes a fixed phase retarder, a tunable phase retarder and a pair of linear polarizers to form a unit. The fixed phase retarder and tunable phase retarder basically utilizes liquid crystals to provide phase retardation, moreover, utilizing birefringence phenomenon possessed by liquid crystals can provide adequate phase retardation. The fixed phase retarder utilizes horizontal orientation of liquid crystal cell to provide fixed phase retardation, while the tunable phase retarder however utilizes homeotropic liquid crystal cell and a rotatable magnet to provide a tunable phase retardation, wherein the tunable phase retarder can provide the positive or negative phase retardation relative to the fixed phase retarder, based on the direction of the magnet's rotating axes and totally use the entire tunable range into adjusting frequencies which can pass through. Besides, the present invention can also serially connect multiple units described above so as to achieve a narrow enough band-pass bandwidth.
Transforming an error-tolerant separable matrix to an error-tolerant disjunct matrix
(2009-01-28)
Chen, Hong-Bin
;
Cheng, Yongxi
;
He, Qian
;
Zhong, Chongchong
;
應用數學系
Recently, Chen and Hwang [H.B. Chen, F.K. Hwang, Exploring the missing link among d-separable, (d) over bar -separable and d-disjunct matrices, Discrete Applied Mathematics 133 (2007) 662-664] provided a method for transforming a separable matrix to a disjunct matrix. In [D.Z. Du, F.K. Hwang, Pooling Designs and Nonadaptive Group Testing - Important Tools for DNA Sequencing, World Scientific, 2006], Du and Hwang attempted to extend this result to its error-tolerant version; unfortunately, they gave an incorrect extension. This note gives a solution to this problem. (C) 2008 Elsevier B.V. All rights reserved.
Symbol time synchronization method for OFDM systems
(2009-01-29)
Chin, Wen-Long
;
Chen, Sau-Gee
A symbol time synchronization method for OFDM systems is disclosed. The invention presents a joint maximum-likelihood (ML) synchronization method for symbol time offset (STO) for OFDM systems. The method is developed in frequency-domain under time-variant multipath channels. By analyzing the received frequency-domain data, a mathematical model for the joint effects of symbol time offset (STO), carrier frequency offset (CFO) and sampling clock frequency offset (SCFO) is derived. The results are used to formulate a log-likelihood function of two consecutive symbols. The joint estimation's method is robust, because it exhibits high performances in high mobility and time-variant multipath fading channels.
NOVEL PHOSPHOR AND FABRICATION OF THE SAME
(2009-01-29)
CHEN, Teng-Ming
;
Chiu, Yi-Chen
;
Huang, Chien Hao
The present invention provides a novel phosphor represent by the following general formula:
NOVEL PHOSPHOR AND FABRICATION OF THE SAME
(2009-01-29)
CHEN, Teng-Ming
;
CHIU, Yi-Chen
The present invention provides a light emitting diode-converted phosphor compound having the following formula:
Tone-Interleaved Coded Modulation Scheme for MIMO OFDM Communication
(2009-01-29)
Wu, Wen-Rong
;
Shen, Shih-Chi
A MIMO OFDM system for TICM is provided. The tone-level interleaver at the transmitter uses a block of NT symbols as its basic unit. This results in different decoding architectures at the receiver. The main advantage of TICM is to merge soft-bit demapping into the Viterbi algorithm. Taking the advantage of the trellis structure inherent in the Viterbi algorithm, TICM can have lower computational complexity and potentially better performance than BICM with the LSD detector and the vector demapper. Although the tone-level interleaving may not have spatial diversity gain, the performance is not affected in 802.11n environments.
Co-evolution positions and rules for antigenic variants of human influenza A/H3N2 viruses
(2009-01-30)
Huang, Jhang-Wei
;
King, Chwan-Chuen
;
Yang, Jinn-Moon
;
生物科技學系
;
生物資訊及系統生物研究所
Background: In pandemic and epidemic forms, avian and human influenza viruses often cause significant damage to human society and economics. Gradually accumulated mutations on hemagglutinin (HA) cause immunologically distinct circulating strains, which lead to the antigenic drift (named as antigenic variants). The "antigenic variants" often requires a new vaccine to be formulated before each annual epidemic. Mapping the genetic evolution to the antigenic drift of influenza viruses is an emergent issue to public health and vaccine development Results: We developed a method for identifying antigenic critical amino acid positions, rules, and co-mutated positions for antigenic variants. The information gain (IG) and the entropy are used to measure the score of an amino acid position on hemagglutinin (HA) for discriminating between antigenic variants and similar viruses. A position with high IG and entropy implied that this position is highly correlated to an antigenic drift. Nineteen positions with high IG and high genetic diversity are identified as antigenic critical positions on the HA proteins. Most of these antigenic critical positions are located on five epitopes or on the surface based on the HA structure. Based on IG values and entropies of these 19 positions on the HA, the decision tree was applied to create a rule-based model and to identify rules for predicting antigenic variants of a given two HA sequences which are often a vaccine strain and a circulating strain. The predicting accuracies of this model on two sets, which consist of a training set (181 hemagglutination inhibition (HI) assays) and an independent test set (31,878 HI assays), are 91.2% and 96.2% respectively. Conclusion: Our method is able to identify critical positions, rules, and co-mutated positions on HA for predicting the antigenic variants. The information gains and the entropies of HA positions provide insight to the antigenic drift and co-evolution positions for influenza seasons. We believe that our method is robust and is potential useful for studying influenza virus evolution and vaccine development.
Enhancement of metal bioleaching from contaminated sediment using silver ion
(2009-01-30)
Chen, Shen-Yi
;
Lin, Jih-Gaw
;
環境工程研究所
;
Institute of Environmental Engineering
A silver-catalyzed bioleaching process was used to remove heavy metals from contaminated sediment in this study. The effects of silver concentration added on the performance of bioleaching process were investigated. High pH reduction rate was observed in the bioleaching process with silver ion. The silver ion added in the bioleaching process was incorporated into the lattice of the initial sulfide through a cationic interchange reaction. This resulted in the short lag phase and high metal solubilization in the bioleaching process. The maximum pH reduction rate and the ideal metal solubilization were obtained in the presence of 30 mg/L of silver ion. When the added silver ion was greater than 30 mg/L, the rates of pH reduction and metal solubilization gradually decreased. The solubilization efficiencies of heavy metals (Cu, Zn, Mn, Ni and Cr) were relatively high in the silver-enhanced bioleaching process, except Pb. No apparent effect of silver ion on the growth of sulfur-oxidizing bacteria was found in the bioleaching. These results indicate that the kinetics of metal solubilization can be enhanced by the addition of silver ion. (C) 2008 Elsevier B.V. All rights reserved
Transiently chaotic neural networks with piecewise linear output functions
(2009-01-30)
Chen, Shyan-Shiou
;
Shih, Chih-Wen
;
應用數學系
;
Department of Applied Mathematics
Admitting both transient chaotic phase and convergent phase, the transiently chaotic neural network (TCNN) provides superior performance than the classical networks in solving combinatorial optimization problems. We derive concrete parameter conditions for these two essential dynamic phases of the TCNN with piecewise linear output function. The confirmation for chaotic dynamics of the system results front a successful application of the Marotto theorem which was recently clarified. Numerical simulation on applying the TCNN with piecewise linear output function is carried out to find the optimal solution of it travelling salesman problem. It is demonstrated that the performance is even better than the previous TCNN model with logistic output function. (C) 2007 Elsevier Ltd. All rights reserved.
Transient Dynamics of Coherent Waves Released from Quantum Billiards and Analogous Observation from Free-Space Propagation of Laser Modes
(2009-01-30)
Chen, C. C.
;
Yu, Y. T.
;
Chen, Ross C. C.
;
Huang, Y. J.
;
Su, K. W.
The transient dynamics of the eigenstates and coherent states released from a square quantum billiard is analytically and numerically investigated. It is experimentally verified that this transient dynamic can be analogously observed with the free-space propagation of the lasing modes emitted from the laterally confined, vertically emitted cavities. Furthermore, we exploit a chaotically shaped cavity to originally demonstrate the diffraction-in-time characteristics of the chaotic wave functions. It is found that the transient patterns of chaotic wave functions exhibit a striking feature of random branching behavior with the appearance of intricate interference fringes.
Stimuli-Responsive Controlled Drug Release from Magnetic-Sensitive Silica Nanospheres
(2009-02-01)
Hu, Shang-Hsiu
;
Liu, Ting-Yu
;
Huang, Hsin-Yang
;
Liu, Dean-Mo
;
Chen, San-Yuan
A novel method for control burst releasing of drug via a high frequency magnetic field (HFMF) from magnetic-sensitive silica nanospheres was developed. The nanospheres were synthesized by a combination of emulsion and sol-gel process with the particles controlled at about 80 nm in diameter. Under repeated exposures to the high frequency magnetic stimulus, the drug release behaviors showed reproducible slow-to-burst profiles while consecutively applying the magnetic stimulus at 10-min switching time and the release profile restored immediately when the stimulus was removed. By taking this non-contact control-burst method, the magnetic silica nanospheres can be designed to treat the cancer therapy and urgent physiological needs.
Expert diagnostic system for moving-coil loudspeakers using nonlinear modeling
(2009-02-01)
Bai, Mingsian R.
;
Huang, Chau-Min
;
機械工程學系
;
Department of Mechanical Engineering
This work aims at the development of an expert diagnostic system for moving-coil loudspeakers. Special emphasis is placed on the defects resulting from loudspeaker nonlinearities. As a loudspeaker operates in the large signal domain, nonlinear distortions may arise and impair sound quality. Analysis of nonlinear responses can shed light on potential design faults of a loudspeaker. By exploiting this fact, this expert diagnostic system enables classification of design faults using a defect database alongside an intelligent fault inference module. Six types of defects are investigated in this paper. A large signal model based on electromechanical analogous circuits is employed for generating the defect database, through which a neural-fuzzy network is utilized for inferring the defect types. Numerical simulations and experimental investigations were undertaken for validating the loudspeaker diagnostic system. (C) 2009 Acoustical Society of America. [DOI: 10.1121/1.3058639]