Browsing by Issue Date, starting with "2007-03-01"

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Numerical ranges of companion matrices
(2007-03-01)
Gau, Hwa-Long
;
Wu, Pei Yuan
;
應用數學系
;
Department of Applied Mathematics
We show that an n-by-n companion matrix A can have at most n line segments on the boundary a(A) of its numerical range W(A), and it has exactly n line segments on W(A) if and only if, for n odd, A is unitary, and, for n even, A is unitarily equivalent to the direct sum A(1) circle plus A(2) of two (n/2)-by-(n/2) companion matrices [GRAPHICS] with 1 <= vertical bar u vertical bar < tan(pi/n) + sec(pi/n). (c) 2006 Elsevier Inc. All rights reserved.
Quantum pump driven fermionic Mach-Zehnder interferometer
(2007-03-01)
Chung, S. -W. V.
;
Moskalets, M.
;
Samuelsson, P.
;
電子物理學系
;
電子工程學系及電子研究所
We have investigated the characteristics of the currents in a pump driven fermionic Mach-Zehnder interferometer. The system is implemented in a conductor in the quantum Hall regime, with the two interferometer arms enclosing an Aharonov-Bohm flux Phi. Two quantum point contacts with transparency modulated periodically in time drive the current and act as beam splitters. The current has a flux-dependent part I-(Phi) as well as a flux-independent part I-(0). Both current parts show oscillations as a function of frequency on the two scales determined by the lengths of the interferometer arms. In the nonadiabatic, high-frequency regime I-(Phi) oscillates with a constant amplitude while the amplitude of the oscillations of I-(0) increases linearly with frequency. The flux-independent part I-(0) is insensitive to temperature while the flux-dependent part I-(Phi) is exponentially suppressed with increasing temperature. We also find that for low amplitude, adiabatic pumping rectification effects are absent for semitransparent beam splitters. Inelastic dephasing is introduced by coupling one of the interferometer arms to a voltage probe. For a long charge relaxation time of the voltage probe, giving a constant probe potential, I-(Phi) and the part of I-(0) flowing in the arm connected to the probe are suppressed with increased coupling to the probe. For a short relaxation time, with the potential of the probe adjusting instantaneously to give zero time-dependent current at the probe, only I-(Phi) is suppressed by the coupling to the probe.
Low-temperature CVD growth of carbon nanotubes for field emission application
(2007-03-01)
Chen, Kuang-Chung
;
Chen, Chia-Fu
;
Lee, Jen-Hao
;
Wu, Tai-Lin
;
Hwang, Chian-Liang
For field emission application, carbon nanotube emitters were synthesized on catalyst-mixed thick-film electrode lower than 500 degrees C by chemical vapor deposition (CVD) method. Mixtures of Ni/tetraethyl silicate (TEOS) and conducting Ag powders were applied to fabricate the electrode by screen-printing processes. These processes are simple, low cost and easy to scale up for large sized panels. The field emission properties performed uniform emission image and high brightness (no less than 500 nits). The turn-on electric field was about 3.85 V/mu m with an emission current destiny of 10 mu A/cm(2), and the achieved current density was 1 mA/cm(2) driven by 5 V/mu m. (c) 2006 Elsevier B.V. All rights reserved.
Two-stage biofilter for effective NH3 removal from waste gases containing high concentrations of H2S
(2007-03-01)
Chung, Ying-Chien
;
Ho, Kuo-Ling
;
Tseng, Ching-Ping
;
生物科技學系
;
Department of Biological Science and Technology
A high H2S concentration inhibits nitrification when H2S and NH3 are simultaneously treated'in a single biofilter. To improve NH3 removal from waste gases containing concentrated H2S, a two-stage biofilter was designed to solve the problem. In this study, the first biofilter, inoculated with Thiobacillus thioparus, was intended mainly to remove H2S and to reduce the effect of H2S concentration on nitrification in the second biofilter, and the second biofilter, inoculated with Nitrosomonas europaea, was to remove NH3. Extensive studies, which took into account the characteristics of gas removal, the engineering properties of the two biofilters, and biological parameters, were conducted in a 210-day operation. The results showed that an average 98% removal efficiency for H2S and a 100% removal efficiency for NH3 (empty bed retention time = 23-180 sec) were achieved after 70 days. The maximum degradation rate for NH3 was measured as 2.35 g N day(-1) kg of dry granular activated carbon'. Inhibition of nitrification was not found in the biofilter. This two-stage biofilter also exhibited good adaptability to shock loading and shutdown periods. Analysis of metabolic product and observation of the bacterial community revealed no obvious acidification or alkalinity phenomena. In addition, a lower moisture content (similar to 40%) for microbial survival and low pressure drop (average 24.39 mm H2O m(-1)) for system operation demonstrated that the two-stage biofilter was energy saving and economic. Thus, the two-stage biofilter is a feasible system to enhance NH3 removal in the concentrated coexistence of H2S.
Dormancy-break and germination in seeds of Prunus campanulata (Rosaceae): role of covering layers and changes in concentration of abscisic acid and gibberellins
(2007-03-01)
Chen, Shun-Ying
;
Chien, Ching-Te
;
Chung, Jeng-Der
;
Yang, Yuh-Shyong
;
Kuo, Shing-Rong
Intact seeds (seed + endocarp) from freshly harvested fruits of Prunus campanulata were dormant, and required 4-6 weeks of warm followed by 8 weeks of cold stratification for maximum germination percentage. Removing both endocarp and seed coat, however, promoted germination in a high percentage of non-stratified seeds. Treatment of intact, non-stratified seeds with gibberellic acid (GA(3)) was only partially effective in breaking dormancy. However, GA(3) promoted germination of non-stratified seeds in which the endocarp (but not the seed coat) had been removed. The order of abscisic acid (ABA) concentration in fresh seeds was endocarp > seed coat > embryo, and its concentration in endocarp plus seed coat was about 6.2-fold higher than that in the embryo. Total ABA contents of seeds subjected to warm and/or cold moist stratification were reduced 6- to 12-fold. A higher concentration of GA(4) was detected in embryos of non-dormant than in those of dormant seeds. Fluridone, a carotenoid biosynthesis inhibitor, was efficient in breaking dormancy of Prunus seeds. Paclobutrazol, a GA biosynthesis inhibitor, completely inhibited seed germination, and the inhibitory effect could be partially reversed by GA(4), but not by GA(3) Thus, dormancy in P campanulata seeds is imposed by the covering layers. Dormancy break is accompanied by a decrease in ABA content of the covering layers and germination by an increase of embryonic GA(4) content.
Purification of single qubits by collinear photons
(2007-03-01)
Odate, Satoru
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Takeno, Yuishi
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Kobayashi, Takayoshi
;
電子物理學系
;
Department of Electrophysics
We have demonstrated purification of a single qubit by two collinear photons, one of which was time-delayed. Our method can be applied to a single qubit many times, and the qubit can be purified to an arbitrarily high degree of purity. Thus, by repeating this method we can make the statistical error that single qubits incur along a transmission channel much smaller.
Layout dependence on threshold voltage instability of hydrogenated amorphous silicon thin film transistors
(2007-03-01)
Tseng, Huai-Yuan
;
Chiang, Ko-Yu
;
Lu, Hau-Yan
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Kung, Chen-Pang
;
Chang, Ting-Chang
In this paper, we discuss the threshold voltage instability of two distinct layouts of hydrogenated amorphous silicon thin film transistors (a-Si:H TFTs). By simultaneously applying gate and drain bias stress, we show that the average threshold voltage shift of circular a-Si:H TFTs is 54% less than that of conventional inverted staggered a-Si:H TFTs. This result is primarily due to that the circular layout reduces the channel electron concentration. ISE-DESSIS (Integrated System Engineering DEvice Simulation for Smart Integrated Systems) was used to simulate the parallel electric field and obtain the total channel electron concentration. The simulation results closely correspond to the explanation in this study. These results indicate a significant impact of improving threshold voltage stability by a layout method.
Study of an axial flow cyclone to remove nanoparticles in vacuum
(2007-03-01)
Tsai, Chuen-Jinn
;
Chen, Sheng-Chieh
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Przekop, Rafal
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Moskal, Arkadiusz
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環境工程研究所
An axial flow cyclone for removing nanoparticles was tested for collection efficiency. Data were validated numerically in vacuum conditions of several Torrs, with flow rates of 0.35-0.57 slpm. The experimental cutoff aerodynamic diameter of the cyclone ranged from 21.7 to 49.8 nm. A 3-D numerical simulation was conducted first to calculate detailed flow and pressure fields, then a Brownian Dynamics simulation was done to determine the collection efficiency of nanoparticles. Both centrifugal force and Brownian diffusion were taken into account. The simulated results for both pressure drop and cutoff aerodynamic diameter are in good agreement with the experimental data. In comparison, previous theories using simplified tangential flow field assumption are not able to predict collection efficiencies accurately. The numerical model developed in this study can facilitate cyclone design to classify valuable nanopowders below a certain diameter, or to remove toxic nanoparticles from the vacuum exhaust of process chambers commonly used in high-tech industries.
Forecasting electricity market pricing using artificial neural networks
(2007-03-01)
Pao, Hsiao-Tien
;
管理科學系
;
Department of Management Science
Electricity price forecasting is extremely important for all market players, in particular for generating companies: in the short term, they must set up bids for the spot market; in the medium term, they have to define contract policies; and in the long term, they must define their expansion plans. For forecasting long-term electricity market pricing, in order to avoid excessive round-off and prediction errors, this paper proposes a new artificial neural network (ANN) with single output node structure by using direct forecasting approach. The potentials of ANNs are investigated by employing a rolling cross validation scheme. Out of sample performance evaluated with three criteria across five forecasting horizons shows that the proposed ANNs are a more robust multi-step ahead forecasting method than autoregressive error models. Moreover, ANN predictions are quite accurate even when the length of the forecast horizon is relatively short or long. (c) 2006 Elsevier Ltd. All rights reserved.
編輯室報告
(國立陽明交通大學出版社, 2007-03-01)
朱元鴻
High frequency impedance inverse in MTJ junction
(2007-03-01)
Hsieh, L. C.
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Huang, Y. W.
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Han, X. F.
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Zeng, Z. M.
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Chien, W. C.
The magnetoimpedance effect of magnetic tunnel junction ( MTJ) was investigated at room temperature in the frequency ranged from 100 Hz to 15 MHz. The MR loop with a ratio of 9.49% at 5MHz switches to - 11.51% at 7 MHz, respectively. This indicates the MR loop reverse shape and sign around 6 MHz. This inverse MR effect is explained by the impedance competition among Resistor- Inductor series circuit and Capacitor part. (c) 2006 Elsevier B. V. All rights reserved.
Calibration 90 nm node RF mosfets, including stress degradation
(2007-03-01)
Kao, H. L.
;
Kao, C. H.
;
Chin, A.
;
Liao, C. C.
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電子工程學系及電子研究所
Using a microstrip line layout, a low minimum noise figure (NFmin) of 0.51 dB, at 10 GHZ, was directly measured for 90 nm node NMOSFETs (65 nm physical gate length). The NFmin was located at the peak f(T) of 152 GHz, coinciding with the peak transconductance (g). On the basis of these measurements, a self-consistent model of the DC I-V, S-parameters, and NFmin results was developed, including the changes after hot-carrier stress. (c) 2007 Wiley Periodicals, Inc.
Numerical study on strained InGaAsP/InGaP quantum wells for 850-nm vertical-cavity surface-emitting lasers
(2007-03-01)
Kuo, Y. -K.
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Chen, J. -R.
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Chen, M. -L.
;
Liou, B. -T.
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光電工程學系
The physical and optical properties of compressively strained InGaAsP/InGaP quantum wells for 850-nm vertical-cavity surface-emitting lasers are numerically studied. The simulation results show that the maximum optical gain, transparency carrier densities, transparency radiative current densities, and differential gain of InGaAsP quantum wells can be efficiently improved by employing a compressive strain of approximately 1.24% in the InGaAsP quantum wells. The simulation results suggest that the 850-nm InGaAsP/InGaP vertical-cavity surface-emitting lasers have the best laser performance when the number of quantum wells is one, which is mainly attributed to the non-uniform hole distribution in multiple quantum wells due to high valence band offset.
Tight-binding theory for coupled photonic crystal waveguides
(2007-03-01)
Chien, F. S. -S
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Tu, J. B.
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Hsieh, W. -F.
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Cheng, S. -C.
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光電工程學系
The point-defect coupling under the tight-binding approximation is introduced to describe the behavior of dispersion relations of the guided modes in a single photonic crystal waveguide (PCW) and two coupled identical PCWs. The cross-coupling coefficient beta of a point defect in one PCW to the nearest-neighboring (NN) defect in the other PCW causes the split of the dispersion curves, whereas the cross-coupling coefficient gamma to the next-NN defects causes a sinusoidal modulation to the dispersion curves. Furthermore, the sign of beta determines the parities of the fundamental guided modes, which can be either even or odd, and the inequality parallel to beta parallel to
Comprehensive wave propagation model to improve TDR interpretations for geotechnical applications
(2007-03-01)
Lin, Chin-Ping
;
Tang, Shr-Hong
;
交大名義發表
;
National Chiao Tung University
Time domain reflectometry (TDR) is becoming an important monitoring technique for various geotechnical problems. Better data interpretation and new developments rely on the ability to accurately model the TDR waveform, especially when long cables are used. This study developed an efficient, complete, and general-purpose TDR model that accounts for all wave phenomena including multiple reflection, dielectric dispersion, and cable resistance all together. Inverse analysis based on the TDR wave propagation model is proposed to calibrate the TDR system parameters and determine the TDR parameter that changes with the physical parameter to be monitored. Calibration of TDR cable and data interpretations for various geotechnical applications were demonstrated with laboratory experiments. The excellent match between the simulated and measured waveforms validates the TDR wave propagation model. The results show that the proposed numerical procedure is a relatively simple, efficient and high-resolution tool for probe design, parametric studies, data interpretation, and inverse analyses. This study should provide a sound theoretical foundation for further TDR developments in geotechnical monitoring.
Elastic constants identification of symmetric angle-ply laminates via a two-level optimization approach
(2007-03-01)
Chen, C. M.
;
Kam, T. Y.
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機械工程學系
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Department of Mechanical Engineering
A two-level optimization method for elastic constants identification of symmetric angle-ply laminates is presented. Measured axial and lateral strains of two symmetric angle-ply laminates with different fiber angles are used in the proposed method to identify four elastic constants of the composite laminates. In the first-level optimization process, the theoretically and experimentally predicted axial and lateral strains of a [(45 degrees/-45 degrees)(2)](s) laminate are used to construct the error function which is a measure of the differences between the experimental and theoretical predictions of the axial and lateral strains. The identification of the material constants is then formulated as a constrained minimization problem in which the best estimates of the shear modulus and Poisson's ratio of the laminate are determined by making the error function a global minimum. The problem of this level of optimization is then solved using a multi-start global minimization algorithm. In the second-level optimization process, the shear modulus and Poisson's ratio determined in the previous level of optimization are kept constant while the Young's moduli of the second angle-ply laminate with fiber angles other than 45 degrees are identified using the same minimization technique that has been used in the previous level. The accuracy of the proposed method are studied by means of a number of numerical examples on the material constants identification of symmetric angle-ply laminates made of different composite materials. Finally, static tensile tests of [(45 degrees/-45 degrees)(2)](s) and [(30 degrees/-30 degrees)(2)](s) laminates made of Gr/ep composite material are performed to measure the strains of the laminates. The experimental data are then used to identify the elastic constants of the laminates. The excellent results obtained in the experimental investigation have demonstrated the feasibility and applications of the proposed method. (c) 2006 Elsevier Ltd. All rights reserved.
美麗城的步行者：中國大姐的巴黎街角
(國立陽明交通大學出版社, 2007-03-01)
羅惠珍
BC級戰犯和“法”的暴力
(國立陽明交通大學出版社, 2007-03-01)
高橋哲哉
;
王前
;
孫軍悅
Composites of UHMWPE fiber reinforced PU/epoxy grafted interpenetrating polymer networks
(2007-03-01)
Lin, S. P.
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Han, J. L.
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Yeh, J. T.
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Chang, F. C.
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Hsieh, K. H.
Several polyurethane-modified epoxy resins (PU/DGEBA-g-IPNs) were synthesized and characterized through a series tests, including differential scanning calorimetry and mechanical property measurements, such as tensile, Izod, bending and shear strengths were investigated in the study. The PU/DGEBA-g-IPNs and neat DGEBA as matrices for UHMWPE fiber-reinforced and aramid fiber-reinforced composites were prepared for comparison of their mechanical properties. The degree of plasma treatment, the polyurethane content, and the type of polyol in the polyurethane within the matrix of the composite were investigated through mechanical and bulletproof testing. (c) 2006 Elsevier Ltd. All rights reserved.
Detecting and adjusting ordinal and cardinal inconsistencies through a graphical and optimal approach in AHP models
(2007-03-01)
Li, Han-Lin
;
Ma, Li-Ching
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交大名義發表
;
National Chiao Tung University
An AHP model suffering from significant cardinal or/and ordinal inconsistencies in its preference matrix is difficult to rank rationally the alternatives. This study proposes an iterative method to assist a decision maker to detect/adjust inconsistencies and to represent his/her judgments properly. A Gower plot is first used to detect ordinal and cardinal inconsistencies. Two optimization models are then constructed to provide suggeted adjustments upon the request of the decision maker. By examining the Gower plots and numerical suggestions, the decision maker may revise iteratively the preference ratios to improve inconsistencies until all alternatives are ranked. (c) 2005 Elsevier Ltd. All rights reserved.