Browsing by Issue Date, starting with "2009-01-27"

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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]
Effect of connectivity and wettability on the relative permeability of NAPLs
(2009-02-01)
Chang, Liang-Cheng
;
Chen, Hung-Hui
;
Shan, Hsin-Yu
;
Tsai, Jui-Pin
;
土木工程學系
The characteristic relationships among relative permeability (K(r)), saturation (S) and capillary pressure (P) of NAPLs are the important constitutive laws to simulate the NAPLs flow in the subsurface. In this study, a micro model was used to obtain the values of permeability, saturation for the multi-phase flow of five fluid-pairs. The perspective micro model allows one to clearly observe the multiphase flow and allow this study to precisely measure the fluid saturation by digital image analysis. The experimental results showed hysteresis phenomenon of relative permeability versus saturation and that was not interpreted by previous studies. By carefully examining the recorded images, this study found that the degree of the connectivity for the micro channel occupied by wetting phase fluid could influence the relative permeability. Therefore, for the same saturation, the relative permeability in the imbibition is higher than that in the drainage. The results of the K(r)-S experiments for five fluid-pairs also showed that the residual saturation of wetting phase fluid decreased with the wettability increasing but increased with the interfacial tension increasing. Those interpretations and experimental results are valuable references for groundwater remediation and oil reservoir development.
Johnson's rule, composite jobs and the relocation problem
(2009-02-01)
Cheng, T. C. E.
;
Lin, B. M. T.
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Two-machine flowshop scheduling to minimize makespan is one of the most well-known classical scheduling problems. Johnson's rule for solving this problem has been widely cited in the literature. We introduce in this paper the concept of composite job, which is an artificially constructed job with processing times such that it will incur the same amount of idle time oil the second machine as that incurred by a chain of jobs in a given processing sequence. This concept due to Kurisu first appeared in 1976 to deal with the two-machine flowshop scheduling problem involving precedence constraints among the jobs. We show that this concept can be applied to reduce the computational time to solve some related scheduling problems. We also establish a link between solving the two-machine flowshop makespan minimization problem using Johnson's rule and the relocation problem introduced by Kaplan. We present an intuitive interpretation of Johnson's rule in the context of the relocation problem. (c) 2007 Elsevier B.V. All rights reserved.
Performance Improvement of Polycrystalline Silicon Nanowire Thin-Film Transistors by a High-k Capping Layer
(2009-02-01)
Lee, Ko-Hui
;
Hsu, Hsing-Hui
;
Lin, Horng-Chih
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
In this work, a novel polycrystalline silicon (poly-Si) nanowire thin-film transistor (NW-TFT) with side-gated configuration and a high-k material capping was fabricated and characterized. It was found that the gate fringing field effect via the high-k passivation layer can effectively improve the device performance in terms of higher ON current, larger ON/OFF current ratio, and steeper subthreshold slope (SS). The drain-induced barrier lowering (DIBL) effect is also effectively suppressed owing to better gate control. (C) 2009 The Japan Society of Applied Physics
Investigating Importance Weighting of Satisfaction Scores from a Formative Model with Partial Least Squares Analysis
(2009-02-01)
Wu, Chia-Huei
;
Chen, Lung Hung
;
Tsai, Ying-Mei
;
經營管理研究所
;
Institute of Business and Management
This study introduced a formative model to investigate the utility of importance weighting on satisfaction scores with partial least squares analysis. Based on the bottom-up theory of satisfaction evaluations, the measurement structure for weighted/unweighted domain satisfaction scores was modeled as a formative model, whereas the measurement structure for global satisfaction scores was modeled as a reflective model according to top-down theory. The purpose was to see if the predictive effect of importance-weighted domain satisfaction scores is stronger than unweighted domain satisfaction scores in predicting global satisfaction scores. Three datasets in life, self, and job satisfaction were analyzed. In the life satisfaction dataset, 237 undergraduates at Central Taiwan University of Science and Technology voluntarily provided their responses. The mean age of respondents was 20.80 years (SD = 1.05). In the self-satisfaction dataset, 269 undergraduates at National Taiwan University provided their responses. The mean age of respondents was 19.78 years (SD = 1.44). Finally, in the job satisfaction dataset, 557 staff members in seven Taiwan provincial hospitals provided their responses. The mean age of respondents was 35.87 years (range from 21 to 65, SD = 8.60). Three measures of domain satisfaction, domain importance, and global satisfaction were collected in each dataset. Partial least squares analysis was used in model estimation. All the results revealed that unweighted domain satisfaction scores have a stronger predictive effect for global satisfaction measures than importance-weighted domain satisfaction scores, indicating that importance weighting on satisfaction scores did not have an empirical benefit.
I Want Products My Own Way, But Which Way? The Effects of Different Product Categories and Cues on Customer Responses to Web-based Customizations
(2009-02-01)
Chang, Chia-Chi
;
Chen, Hui-Yun
;
管理科學系
;
Department of Management Science
Mass customization is a strategy that has been adopted by companies to tailor their products in order to match customer needs more precisely. Therefore, to fully capture the value of mass customization, it is crucial to explore how customers react to mass customization. In previous studies, an implied premise has been that consumers are keen to embrace customized products, and this assumption has also been treated by firms as a prerequisite for successful mass customization strategies. However, an undesirable complexity may result from difficult configuration processes that may intimidate and confuse some customers. Hence, this study explores strategies that marketers can employ to facilitate the customization process. Specifically, this study investigates how to enhance customer satisfaction and purchase decision toward customized products by providing cues compatible with the product category. It is hypothesized that for search products, customers rely more on intrinsic cues when making configuration decisions. On the other hand, for experience products, customers perceive extrinsic cues to be more valuable in assisting them to make configuration decisions. The results suggest that consumers tend to respond more favorably toward customized search products when intrinsic cues are provided than when extrinsic or irrelevant ones are provided. In contrast, when customizing experience products, customers tend to depend more on extrinsic cues than on intrinsic or irrelevant ones.
Selective Device Structure Scaling and Parasitics Engineering: A Way to Extend the Technology Roadmap
(2009-02-01)
Wei, Lan
;
Deng, Jie
;
Chang, Li-Wen
;
Kim, Keunwoo
;
Chuang, Ching-Te
We propose a path for extending the technology roadmap when currently considered technology boosters (e.g., strain, high-kappa/metal gate) reach their limits and physical gate length can no longer be effectively scaled down. By judiciously engineering the device parasitic resistance and parasitic capacitance, and considering the impact of the interconnect wiring capacitance, we propose scenarios of selective device structure scaling that will enable technology scaling and contacted gate pitch scaling for several generations beyond the currently perceived limits.
An overview of theory and practice on process capability indices for quality assurance
(2009-02-01)
Wu, Chien-Wei
;
Pearn, W. L.
;
Kotz, Samuel
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Process capability indices (PCIS), C(p), C(a), C(pk), C(pm), and C(pmk) have been developed in certain manufacturing industry as capability measures based on various criteria, including process consistency, process departure from a target, process yield, and process loss. It is noted in certain recent quality assurance and capability analysis works that the three indices, C(pk), C(pm), and C(pmk) provide the same lower bounds on the process yield. In this paper, we investigate the behavior of the actual process yield, in terms of the number of non-conformities (in ppm), for processes with fixed index values of C(pk) = C(pm) = C(pmk), possessing different degrees of process centering. We also extend Johnson's [1992. The relationship of C(pm) to squared error loss. journal of Quality Technology 24, 211-215] result formulating the relationship between the expected relative squared loss and PCIs. Also a comparison analysis among PCIs is carried out based on various criteria. The result illustrates some advantages of using the index C(pmk) over the indices C(pk) and C(pm) in measuring process capability (yield and loss), since C(pmk) always provides a better protection for the customers. Additionally, several extensions and applications to real world problem are also discussed. The paper contains some material presented in the Kotz and Johnson [2002. Process capability indices-a review, 1992-2000. journal of Quality Technology 34(1),1-19] survey but from a different perspective. It also discusses the more recent developments during the years 2002-2006. (C) 2009 Elsevier B.V. All rights reserved.
Application of Pd/Ge/Cu alloyed ohmic contact system to n-type GaAs for fully Cu-metallized InGaP/GaAs HBTs
(2009-02-01)
Chen, Ke-Shian
;
Chang, Edward Yi
;
Lin, Chia-Ching
;
Lee, Cheng-Shih
;
材料科學與工程學系
Use of the Pd/Ge/Cu multilayers as the emitter and collector ohmic metal for the fully Cu-metallized InGaP/GaAs heterojunction bipolar transistors is studied. The Pd/Ge/Cu ohmic contact exhibited a very low contact resistance of 5.73 x 10(-7) Omega cm(2) at a low annealing temperature (250 degrees C) and the microstructure evolution of Pd/Ge/Cu ohmic contact was investigated using transmission electron microscopy and energy dispersive spectrometer. We also did some comparisons between the Pd/Ge/Cu, Pd/Ge/Ti/Pt/Cu, and the traditional Au/Ge/Ni/Au ohmic contact structures to n-type GaAs. The common emitter I-V curves and Gummel plot of these Cu-metallized HBTs using Pd/Ge/Cu ohmic contact and Cu interconnects showed similar electrical characteristics as those HBTs with conventional Au-metallization. The cutoff frequency (f(T)) of 3 x 20-mu m-emitter-area devices was about 38 GHz. During both the current-accelerated stress test (110 kA/cm(2) stress for 24 h) and the thermal stability test (annealing at 250 degrees C for 24 h), the fully Cu-metallized HBT with Pd/Ge/Cu ohmic contact and Cu interconnects showed almost no obvious degradation in electrical characteristics. The results show that the Pd/Ge/Cu ohmic contact in combination with the Cu interconnects can be used on HBT devices to achieve the Au-free fully Cu-metallized lnGaP/GaAs HBTs, and the devices exhibit good device performance. (C) 2008 Elsevier Ltd. All rights reserved.