Browsing by Issue Date, starting with "2005-02-01"

Now showing 1 - 20 of 67269

Applications of genetic algorithms in industry
(2005-02-01)
Wu, MC
;
Wortmann, H
;
Szirbik, N
;
交大名義發表
;
National Chiao Tung University
2 V-operated InGaP-AlGaAs-InGaAs enhancement-mode pseudomorphic HEMT
(2005-02-01)
Chu, LH
;
Chang, EY
;
Chen, SH
;
Lien, YC
;
Chang, CY
A low-voltage single power supply enhancement-mode InGaP-AlGaAs-InGaAs pseudomorphic high-electron mobility transistor (PHEMT) is reported for the first time. The fabricated 0.5 x 160 mum(2) device shows low knee voltage of 0.3 V, drain-source current (I-DS) of 375 mA/mm and maximum transconductance of 550 mS/mm when drain-source voltage (V-DS) was 2.5 V. High-frequency performance was also achieved; the cut-off frequency(F-t) is 60 GHz and maximum oscillation frequency(F-max) is 128 GHz. The noise figure of the 160-mum gate width device at 17 GHz was measured to be 1.02 dB with 10.12 dB associated gain. The E-mode InGaP-AlGaAs-InGaAs PHEMT, exhibits a high output power density of 453 mW/mm with a high linear gain of 30.5 dB at 2.4 GHz. The E-mode PHEMT can also achieve a high maximum power added efficiency (PAE) of 70%, when tuned for maximum PAE.
Study of air bearing with grooved disk surface in near-field optical disk drives
(2005-02-01)
Wang, HC
;
Liu, TS
;
Chang, CS
;
機械工程學系
;
Department of Mechanical Engineering
To achieve stable flying height of a pickup head in near-field optical disk drives, the influence of disk grooves on the airflow of an air bearing deserves investigation, since at a very low flying height, groove geometry is comparable to the flying height. This paper aims to compare air bearing airflows between near-field optical disks with grooved surface and conventional disks without grooved surface. Computational results show that grooved disks generate smaller pressure than smooth disks since grooves can accommodate air molecules and tune air pressure. Flying higher makes pressure magnitudes closer between grooved disks and smooth disks in negative pressure area on slider bottoms. Further, track pitches and groove depths essentially do not affect pressure at rails.
Photocatalytic oxidation of gaseous DMF using thin film TiO2 photocatalyst
(2005-02-01)
Chang, CP
;
Chen, JN
;
Lu, MC
;
Yang, HY
;
環境工程研究所
The heterogeneous photocatalytic oxidation of gaseous N,N'-dimethylformamide (DMF) widely used in the manufacture of synthetic leather and synthetic textile was investigated. The experiments were carried out in a plug flow annular photoreactor coated with Degussa P-25 TiO2. The oxidation rate was dependent on DMF concentration, reaction temperature, water vapor, and oxygen content. Photocatalytic deactivation was observed in these reactions. The Levenspiel deactivation kinetic model was used to describe the decay of catalyst activity. Fourier transform infrared (FTIR) was used to characterize the surface and the deactivation mechanism of the photocatalyst. Results revealed that carbonylic acids, aldehydes, amines, carbonate and nitrate were adsorbed on the TiO2 surface during the photocatalytic reaction. The ions, NH4+ and NO3-, causing the deactivation of catalysts were detected on the TiO2 surface. Several treatment processes were applied to find a suitable procedure for the regeneration of catalytic activity. Among these procedures, the best one was found to be the H2O2/UV process. (C) 2004 Elsevier Ltd. All rights reserved.
Experimental realization of breaking diffraction limit by planar negative-index metamaterials in free space
(2005-02-01)
Lih, JS
;
Wang, YS
;
Lu, MC
;
Huang, YC
;
Chen, KH
The sharpness of the image formed by a conventional lens is always limited by the wavelength of light. Recently, Pendry proposed a superlens, with a negative refractive index. such that the resolution is not limited by wavelength. Herein, we report direct experimental evidence of Pendry's superlens breaking the diffraction limit, in the microwave range of the X band (8-12 GHz), with a periodic array of split ring resonators and continuous wires; i.e. a meta-material with negative index of refraction.
濟南路上那棵玉蘭
(2005-02-01)
管管
Day-to-day vehicular flow dynamics in intelligent transportation network
(2005-02-01)
Cho, HJ
;
Hwang, MC
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
In this paper, a flow evolution model is developed by using the dynamical system approach for a vehicular network equipped with predicted travel information. The concerned system variables, path flow, and predicted minimal travel time of an origin-destination (OD) pair, are measured on the peak-hour-average base for each day. The time change rates of these two variables are formulated as a system of ordinary differential equations under the assumption of daily learning and adaptive processes for commuters. By incorporating the total perceived travel time loss (or saving) into the proposed models, time change rates of path flows are generated with a flow-related manner to prevent path flow dynamics from being insensible to traffic congestion which had been formulated in the existing studies. Heterogeneous models with various user adjusting sensitivities and predicted travel information are also presented. Equilibrium solutions of the proposed network dynamics satisfy the Wardrop user equilibria and are proved to be asymptotically stable by using the stability theorem of Lyapunov. The issue of existence and uniqueness of solutions is proved both on the lemma of Lipschitz condition and the fundamental theorem of ordinary differential equations. In addition, some simple examples are demonstrated to show the asymptotic behaviors of the proposed models numerically. (c) 2005 Elsevier Ltd. All rights reserved.
Parameter estimation for leaky aquifers using the extended Kalman filter, and considering model and data measurement uncertainties
(2005-02-01)
Yeh, HD
;
Huang, YC
;
環境工程研究所
;
Institute of Environmental Engineering
A method using the extended Kalman filter (EKF) is proposed to identify the hydraulic parameters in leaky aquifer systems both with and without considering the aquitard storage. In the case without considering the aquitard storage, Hantush and Jacob's model combined with EKF can optimally determine the parameters for the leaky aquifer when analyzing the drawdown data. Coupled with Neuman and Witherspoon's model, the EKF is also employed to estimate the four parameters of aquifers. The observed drawdown data may be either interpolated using the Lagrangian polynomial or recursively used while implementing the EKF. The proposed method can identify the parameters, using part of the interpolated drawdown data or recursively used data, and obtains results with good accuracy. In the field-pumping test, a long pumping time may not be necessary if the proposed method is implemented on a computer, which is connected to pressure transducers and a data logger. In the process of parameter estimation, the leakage coefficient changes marginally for the first few observations. This phenomenon reflects the fact that there is a time lag between the start of pumping and the leakage effect on the drawdown. The analyses of the data uncertainty demonstrate that the EKF approach is applicable for drawdown data even when it contains white noise or temporal correlated noise. Finally, the choice between Hantush and Jacob's model and Neuman and Witherspoon's model depends on the hydrogeological condition of the aquifer system indicated in the analyses of the model uncertainty. Hantush and Jacob's model is shown to be a good choice for representing the leaky aquifer system if, the aquitard storage is comparatively small. (C) 2004 Elsevier B.V. All rights reserved.
Dynamic range improvement of multistage multibit Sigma Delta modulator for low oversampling ratios
(2005-02-01)
Chang, TH
;
Dung, LR
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents an improved architecture of the multistage multibit sigma-delta modulators (EAMs) for wide-band applications. Our approach is based on two resonator topologies, high-Q cascade-of-resonator-with-feedforward (HQCRFF) and low-Q cascade-of-integrator-with-feedforward (LQCEFF). Because of in-band zeros introduced by internal loop filters, the proposed architecture enhances the suppression of the in-band quantization noise at a low OSR. The HQCRFF-based modulator with single-bit quantizer has two modes of operation, modulation and oscillation. When the HQCRFF-based modulator is operating in oscillation mode, the feedback path from the quantizer output to the input summing node is disabled and hence the modulator output is free of the quantization noise terms. Although operating in oscillation mode is not allowed for single-stage SigmaDeltaM, the oscillation of HQCRFF-based modulator can improve dynamic range (DR) of the multistage (MASH) SigmaDeltaM. The key to improving DR is to use HQCRFF-based modulator in the first stage and have the first stage oscillated. When the first stage oscillates, the coarse quantization noise vanishes and hence circuit nonidealities, such as finite op-amp gain and capacitor mismatching, do not cause leakage quantization noise problem. According to theoretical and numerical analysis, the proposed MASH architecture can inherently have wide DR without using additional calibration techniques.
Activated kinetics of room-temperature-deposited SrTiO(3) thin films investigated by reflection-high-energy-electron-diffraction-monitored annealing at different heating rates
(2005-02-01)
Wang, TC
;
Lee, JY
;
Hsieh, CC
;
Juang, JY
;
Wu, KH
A series of reflection-high-energy-electron-diffraction-monitored annealings with different heating rates have been conducted on Strontium Titanate films deposited by laser ablation at room temperature. All the films exhibited a steep RHEED intensity rise above 660 degrees C during annealing with increasing temperature. The peak temperatures of the intensity derivatives were found to shift at different heating rates, suggesting an activated surface state transition. A Kissinger type plot of the peak temperatures showed an effective activation energy of 4 eV.
Activated kinetics of room-temperature-deposited SrTiO3 thin films investigated by reflection-high-energy-electron-diffraction-monitored annealing at different heating rates
(2005-02-01)
Wang, TC
;
Lee, JY
;
Hsieh, CC
;
Juang, JY
;
Wu, KH
A series of reflection-high-energy-electron-diffraction-monitored annealings with different heating rates have been conducted on Strontium Titanate films deposited by laser ablation at room temperature. All the films exhibited a steep RHEED intensity rise above 660 degrees C during annealing with increasing temperature. The peak temperatures of the intensity derivatives were found to shift at different heating rates, suggesting an activated surface state transition. A Kissinger type plot of the peak temperatures showed an effective activation energy of 4 eV.
Conditional diagnosability measures for large multiprocessor systems
(2005-02-01)
Lai, PL
;
Tan, JJM
;
Chang, CP
;
Hsu, LH
;
資訊工程學系
Diagnosability has played an important role in the reliability of an interconnection network. The classical problem of fault diagnosis is discussed widely and the diagnosability of many well-known networks have been explored. In this paper, we introduce a new measure of diagnosability, called conditional diagnosability, by restricting that any faulty set cannot contain all the neighbors of any vertex in the graph. Based on this requirement, the conditional diagnosability of the n-dimensional hypercube is shown to be 4(n - 2) + 1, which is about four times as large as the classical diagnosability. Besides, we propose some useful conditions for verifying if a system is t-diagnosable and introduce a new concept, called a strongly t-diagnosable system, under the PMC model. Applying these concepts and conditions, we investigate some t-diagnosable networks which are also strongly t-diagnosable.
Detecting earth-skimming and mountain-penetrating tau neutrinos
(2005-02-01)
Lin, GL
;
物理研究所
;
Institute of Physics
In this talk, we discuss issues relevant to the detections of Earth-skimming/mountain-penetrating tau neutrinos. We first argue that there are non-negligible astrophysical tau neutrino fluxes due to neutrino flavor oscillations. We then discuss the rationale for detecting Earth-skimming and mountain-penetrating tau neutrinos. The nu(tau) --> tau conversion efficiencies and the tau-lepton event rate are presented.
Protein metal binding residue prediction based on neural networks
(2005-02-01)
Lin, CT
;
Lin, KL
;
Yang, CH
;
Chung, IF
;
Huang, CD
Over one-third of protein structures contain metal ions, which are the necessary elements in life systems. Traditionally, structural biologists were used to investigate properties of metalloproteins (proteins which bind with metal ions) by physical means and interpreting the function formation and reaction mechanism of enzyme by their structures and observations from experiments in vitro. Most of proteins have primary structures (amino acid sequence information) only; however, the 3-dimension structures are not always available. In this paper, a direct analysis method is proposed to predict the protein metal-binding amino acid residues from its sequence information only by neural networks with sliding window-based feature extraction and biological feature encoding techniques. In four major bulk elements (Calcium, Potassium, Magnesium, and Sodium), the metal-binding residues are identified by the proposed method with higher than 90% sensitivity and very good accuracy under 5-fold cross validation. With such promising results, it can be extended and used as a powerful methodology for metal-binding characterization from rapidly increasing protein sequences in the future.
Improved inventory models with service level and lead time
(2005-02-01)
Chu, P
;
Yang, KL
;
Chen, PS
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper explores the mixed inventory backorder and lost sales problem in which both the lead time and order quantity are treated as decision variables. In a recent paper on Computers and Operations Research, Ouyang and Wu considered this problem. However, their algorithms might not find the optimal solution due to flaws in their solution procedure. We develop some lemmas to reveal the parameter effects and then present two complete procedures for finding the optimal solution for the models. The savings are illustrated by solving the same examples from Ouyang and Wu's paper to demonstrate the superiority of our revised algorithms. (C) 2003 Elsevier Ltd. All rights reserved.
Ip connectivity for gateway GPRS support node
(2005-02-01)
Chen, YK
;
Lin, YB
;
交大名義發表
;
National Chiao Tung University
In the Universal Mobile Telecommunications System, the gateway GPRS support node (GGSN) provides IP connection between the mobile telecommunications network and external packet data networks (e.g., the Internet). Specifically, the GGSN exercises session management to transfer user packets between mobile stations and external data networks. In this article we focus on the GGSN functions for IP connection including access point name processing, IP address allocation, tunneling technologies, and QoS management. Based on our experience as a mobile operator, we give several examples to show how these functions can actually be implemented in a commercial mobile network.
A new approach for classification of generic audio data
(2005-02-01)
Lin, RS
;
Chen, LH
;
資訊工程學系
;
Department of Computer Science
The existing audio retrieval systems fall into one of two categories: single-domain systems that can accept data of only a single type (e.g. speech) or multiple-domain systems that offer content-based retrieval for multiple types of audio data. Since a single-domain system has limited applications, a multiple-domain system will be more useful. However, different types of audio data will have different properties, this will make a multiple-domain system harder to be developed. If we can classify audio information in advance, the above problems can be solved. In this paper, we will propose a real-time classification method to classify audio signals into several basic audio types such as pure speech, music, song, speech with music background, and speech with environmental noise background. In order to make the proposed method robust for a variety of audio sources, we use Bayesian decision function for multivariable Gaussian distribution instead of manually adjusting a threshold for each discriminator. The proposed approach can be applied to content-based audio/video retrieval. In the experiment, the efficiency and effectiveness of this method are shown by an accuracy rate of more than 96% for general audio data classification.
Gain-clamping erbium-doped waveguide amplifier module using optical feedback technique
(2005-02-01)
Yeh, CH
;
Chien, HC
;
Lee, CC
;
Chi, S
;
光電工程學系
A forward optical feedback technique for gain-clamping erbium-doped waveguide amplifier has been proposed and experimentally investigated. Three different saturated tones are selected in this proposed structure over the operation range from 1530 to 1550 nm to realize the amplification behaviors. Therefore, a dynamic range of input signal power from -9 to -40 dBm at 1552 nm is obtained when different power level and lasing position of the saturated tone are applied. In addition, the gain clamping performance has also been investigated experimentally under different operation conditions such as the lasing wavelength, the cavity loss and the input signal wavelength. (C) 2004 Elsevier B.V. All rights reserved.
Investigation of different input-matching mechanisms used in wide-band LNA design
(2005-02-01)
Hu, R
;
Yang, MSC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper analyzes different input-matching mechanisms used in designing the wide-band amplifiers in general, and the low noise amplifiers (LNA) in particular, and their corresponding noise impact. Among them, the most promising one is the reactive-feedback circuit configuration, which is a combination of high-frequency inductive feedback and low frequency capacitive feedback. In this paper the simulated result that both matched input impedance and low noise temperature T-n can be achieved simultaneously over a wide bandwidth in the single-ended low noise amplifier is proved mathematically and is well interpreted. This understanding of reactive feedback is crucial for the future development of ultra-wide-band low-noise amplifiers.
Catalytic wheel, Brownian motor, and biological energy transduction
(2005-02-01)
Tsong, TY
;
Chang, CH
;
物理研究所
;
Institute of Physics
An enzyme turns over, or recycles during each catalytic process. It is a catalytic wheel, analogous to a motor, or an engine. The fuel, or the driving force for the wheel, is the free energy of the substrate (S) to product (P) conversion (DeltaG(R)), or a free energy output of a coupled chemical reaction. When DeltaG(R) of the S --> P reaction is negative the reaction is spontaneous and the down-hill wheel motion requires no external input of energy. When DeltaG(R) is positive the wheel must turn uphill against a workload, a reaction that produces energy must be coupled to the wheel. The synthesis of ATP from ADP and P-i in a cell is an uphill reaction and the energy required for the synthesis is derived from the dissipation of a proton gradient, or an electric potential. This article focuses on mechanisms of action of the uphill catalytic wheels. It is shown that the coupling of an external energy source to an uphill catalytic wheel can be done, with nearly 100% efficiency, by mechanisms of the Brownian Motor. Theory of electroconformational coupling (TEC) is used to construct a Brownian motor, and electric activation of an ion pump, Na, K-ATPase is used to demonstrate its basic principles. A TEC Motor has three essential elements: 1) the ability of the protein to interact with an electric field, 2) existence of at least two conformations of protein that oscillate or fluctuate on interaction with the applied field, and 3) a built-in asymmetry in the molecular interactions with substrate and product. It is shown that the TEC Motor is a generic model and applicable to other types of biological energy transducers.