Browsing by Issue Date, starting with "1999-04-05"

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Comparison of ammonia and monoethanolamine solvents to reduce CO2 greenhouse gas emissions
(1999-04-05)
Yeh, AC
;
Bai, HL
;
環境工程研究所
;
Institute of Environmental Engineering
This paper presents experimental results on the evaluation of two reagents, ammonia (NH3) and monoethanolamine (MEA) solvents, for scrubbing carbon dioxide (CO2) greenhouse gas emissions. The scrubbing of CO2 by NH3 solvent is a novel study developed by the authors, and the MEA process is a traditional process for gas purification of removing CO2. The performance of these two solvents are compared in terms of CO2 removal efficiency and absorption capacity. Test results show that both the CO2 removal efficiency and absorption capacity of NH3 solvent are better than those of MEA solvent under the operating conditions conducted in this study. The maximum CO2 removal efficiency by NH3 solvent can achieve 99% and the CO2 absorption capacity can approach 1.20 kg CO2/kg NH3. On the other hand, the maximum CO2 removal efficiency and absorption capacity by MEA solvent are 94% and 0.40 kg CO2/kg MEA, respectively, under the same operating conditions tested by NH3 solvent. Besides, the temperature increases due to exothermal reactions in the NH3 scrubbing process are lower than those in the MEA scrubbing process. This indicates that the energy requirement for the regeneration of NH3 reagent should be less than that for the regeneration of MEA reagent. (C) 1999 Elsevier Science B.V. All rights reserved.
Experiment on an aperture-coupled leaky-wave antenna with a pencil beam
(1999-04-05)
Kao, NA
;
Hu, CC
;
Wu, JJ
;
Jou, CF
;
傳播研究所
A frequency-scanning leaky-wave antenna with an aperture-coupled feeding structure is presented. The aperture-fed structure is used to excite the microstrip first higher mode. In order in suppress the dominant mode, we add a sequence of covered wire in the center of this antenna. The measured H-plane main beam is a pencil beam, and is continuously scanned 12 degrees as the frequency varies from 9.85 to 10.27 GHz. This feeding structure is very suitable for active phase antenna array applications. (C) 1999 John Wiley & Sons, Inc.
Analysis of drug dissolution data
(1999-04-15)
Lee, JC
;
Chen, DT
;
Hung, HN
;
Chen, JJ
;
統計學研究所
Drug absorption in the human body depends on the dissolution rate of the drug. Suitable dissolution characteristics are important to ensure that the drug will achieve the desired therapeutic effects. To assess the similarity of dissolution rates of several drug lots, we apply a general growth curve model with different covariance structures. The Box-Cox power transformation and the naive log transformation are applied to a function of the dissolution rate. The predictive sample-reuse, or cross-validation, method is employed in selecting an appropriate model with best predictive accuracy. A testing procedure for examining the similarity among the drug lots is also conducted. A partially Bayesian approach is used for the assessment of dissolution equivalence. Copyright (C) 1999 John Wiley & Sons, Ltd.
Syntheses and characterizations of soft-segment ionic polyurethanes
(1999-04-15)
Wang, XL
;
Li, H
;
Tang, XZ
;
Chang, FC
;
應用化學系
Novel soft-segment ionic polyurethane (linear and crosslinking) have been prepared based up on sodium sulfonate-side chains poly(ethylene oxide) (SPEO). SPEO was synthesized by grafting the sodium sulfonate onto the chain of poly(ethylene oxide) with molecular weights of 400, 600, 800, and 1000. The SPEO and the ionic polyurethane were characterized by elemental analysis, IH;NMR, C-13-NMR, gel permeation chromatography, and impedance analysis. The effect of plasticizer on the ionic conductivity of the polyurethane was also investigated. These solid polymer electrolytes possess a higher ionic conductivity (about 10(-6) S/cm at room temperature) than the corresponding sulfonated hard-segment polyurethane electrolytes. The presence of the hydroxyl group in the electrolyte tends to lower the ionic conductivity. Crosslinking of polyurethane results in the enhancement of the dimensional stability, while maintaining the same level of the ionic conductivity. (C) 1999 John Wiley & Sons, Inc.
Ferromagnetic behavior of a triplet superconductor
(1999-04-15)
Knigavko, A
;
Rosenstein, B
;
Chen, YF
;
Huang, HL
;
Lin, MT
Properties of a type II triplet superconductor with equal spin pairing are investigated using the phenomenological Ginzburg-Landau approach. It is shown that there exist two kinds of fluxons: vortices and magnetic skyrmions. Vector nature of the order parameter allows a direct coupling of the effective spin of the condensate to a magnetic field. This coupling, which is reminiscent to Zeeman interaction in the form, significantly modifies the structure of an isolated vortex, as compared to the usual Abrikosov vortex, and changes the energetics of a vortex lattice. If the coupling is sufficiently strong, then magnetization of the triplet superconductor becomes positive at high magnetic fields. Formation of spontaneous vortex state is also possible. (C) 1999 American Institute of Physics. [S0021-8979(99)55408-X].
One-dimensional self-focusing in photorefractive Bi12SiO20 crystal: theoretical modeling and experimental demonstration
(1999-04-15)
Tsai, J
;
Chiou, A
;
Hsieh, TC
;
Hsu, K
;
電子物理學系
We have experimentally demonstrated one-dimensional self-focusing of a laser beam in a photorefractive Bi12SiO20 (BSO) crystal with an externally applied DC field. Fractional change in focal length larger than 50% was measured when the biased field was varied from 2 kV/cm to 8 kV/cm. Based on the band transport model, thin crystal approximation, and gradient index (GRIN) lens approximation, we derive a mathematical expression that describes the effect quantitatively. (C) 1999 Elsevier Science B.V. All rights reserved.
The construction of production performance prediction system for semiconductor manufacturing with artificial neural networks
(1999-04-15)
Huang, CL
;
Huang, YH
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Chang, TY
;
Chang, SH
;
Chung, CH
The major performance measurements for wafer fabrication system comprise WIP level, throughput and cycle time. These measurements are influenced by various factors, including machine breakdown, operator absence, poor dispatching rules, emergency order and material shortage. Generally, production managers use the WIP level profile of each stage to identify an abnormal situation, and then make corrective actions. However, such a measurement is reactive, not proactive. Proactive actions must effectively predict the future performance, analyze the abnormal situation, and then generate corrective actions to prevent performance from degrading. This work systematically constructs artificial neural network models to predict production performances for a semiconductor manufacturing factory. An application for a local DRAM wafer fabrication has demonstrated the accuracy of neural network models in predicting production performances.
Magnetic domain pinning in patterned magneto-optical material
(1999-04-15)
Wu, TH
;
Wu, JC
;
Huang, YW
;
Chen, BM
;
Schieh, HPD
Pinning magnetic domains with defined shapes have been made for magneto-optical thin film material. The pinning array of holes on the substrate was fabricated using electron beam lithography. The domain pinning behaviors were studied by applying an external magnetic field perpendicular to the film plane and imaged by atomic force microscopy in their remanent state. Magnetic domains were found to be pinned inside the hole arrays and reproduced the shapes of the holes. The coercivity in the patterned region is larger than in the nonpatterned region. Moreover, the coercivity inside the hole sites is larger than the land sites. (C) 1999 American Institute of Physics. [S0021-8979(99)38708-9].
Dispersion compensation and gain flattened for a wavelength division multiplexing system by using chirped fiber gratings in an erbium-doped fiber amplifier
(1999-04-15)
Dung, JC
;
Chi, S
;
光電工程學系
;
Department of Photonics
A new technique, using chirped fiber gratings (CFGs) with different dispersions and center frequencies to reflect the different channel pulses at different positions, is proposed to compensate for the accumulated dispersions and flatten the signal gain of the erbium-doped fiber amplifier (EDFA) in a wavelength division multiplexing (WDM) system. A numerical example of the gain flattened and dispersion compensation for four channel multiplexed signals in the 1544-1556 nm wavelength region is shown. (C) 1999 Elsevier Science B.V. All rights reserved.
Synthesis of calix[4]arenes with four different "lower rim" substituents
(1999-04-16)
Shu, CM
;
Chung, WS
;
Wu, SH
;
Ho, ZC
;
Lin, LG
Calix[4]arenes with four different "lower rim" substituents were synthesized following six-step sequences. The first alkyl group (R-1) was introduced using R1X and CH3ONa, and then reaction with R2X and K2CO3 led to the introduction of a second alkyl group (R-2) at the 3-position. Benzoate was introduced as a protecting group at the 1,3-O-disubstituent stage and was removed under basic conditions after the incorporation of the third alkyl group (R-3) With R3X and NaH, The final alkyl group (R-4) was introduced with R4X and NaH to give the chiral title compounds.
創世紀詩社改版將開辦紀念詩獎
(1999-04-16)
江中明
Efficiency of supercritical fluid extraction for determining 4-nonylphenol in municipal sewage sludge
(1999-04-23)
Lin, JG
;
Arunkumar, R
;
Liu, CH
;
環境工程研究所
;
Institute of Environmental Engineering
When the sewage sludge containing the persistent, lipophilic, metabolite 4-nonylphenol (4-NP) has been disposed of in the environment it's toxic nature can lead to serious health risks to human beings and can also affect plants and aquatic organisms. Supercritical fluid extraction (SFE) is a new and powerful technique for extracting the organic contaminants from the solid phase. The present study was conducted to investigate optimal conditions for the quantitative extraction of 4-NP by SFE and to determine the concentration of 4-NP in municipal sewage sludge. The effect of several parameters such as temperature, pressure, static extraction time, dynamic extraction time, CO2 flow-rate, sample mass and modifier on the extraction were investigated. The optimal conditions for die extraction of the spiked sample were fluid pressure 97 bar, temperature 40 degrees C, flow-rate 3.0 ml/min, static extraction time 2 min, dynamic extraction time 5 min and modifier methanol (0.5 ml). Extracts were analyzed by gas chromatography-mass spectrometry. Concentration of 4-NP in the anaerobically degraded sludge of the De-flaw Sewage Treatment plant in Taiwan was found to be 243.9 mg/kg. The extraction efficiency of the SFE method was compared with the conventional Soxhlet extraction method. The overall recovery of the SFE method was found to be greater and the results indicate that SFE is an efficient method for extracting 4-NP from sewage sludge. (C) 1999 Elsevier Science B.V. All rights reserved.
Toughened interpenetrating polymer network materials based on unsaturated polyester and epoxy
(1999-04-25)
Lin, MS
;
Liu, CC
;
Lee, CT
;
應用化學系
;
Department of Applied Chemistry
Simultaneous interpenetrating polymer networks (IPNs) based on epoxy (diglycidyl ether of bisphenol A) and unsaturated polyester (UP) were prepared by using m-xylenediamine and benzoyl peroxide as curing agents. A single glass transition temperature for each IPN was observed with differential scanning calorimetry, which suggests good compatibility of epoxy and UP. This compatibility was further confirmed by the single damping peak of the rheometric dynamic spectroscopy. Curing behaviors were studied with dynamic differential scanning calorimetry, and the curing rates were measured with a Brookfield RTV viscometer. It was noted that an interlock between the two growing networks did exist and led to a retarded viscosity increase. However, the hydroxyl end groups in UP catalyzed the curing reaction of epoxy; in some IPNs where the hydroxyl concentration was high enough, such catalytic effect predominated the network interlock effect, leading to fast viscosity increases. In addition, the entanglement of the two interlocked networks played an important role in cracking energy absorption and reflected in a toughness improvement. (C) 1999 John Wiley & Sons, Inc.
Electrical properties of Ta2O5 thin films deposited on Ta
(1999-04-26)
Ezhilvalavan, S
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The electrical properties of reactively sputtered Ta2O5 thin films with Ta as the bottom electrodes were investigated. Ta films were deposited onto SiO2/n-Si substrates by sputtering in Ar and in situ annealed at 700 degrees C for 10 min in N-2 at a chamber pressure of 20 mTorr. We compared the effectiveness of both as-deposited and annealed Ta bottom electrodes on the leakage characteristics of Ta2O5 thin films. We also envisaged the influence of the surface roughness and morphology of the Ta bottom electrode in modifying the resultant microstructure of the annealed Ta2O5 films. Present studies demonstrate the use of Ta as a potential bottom electrode material to replace the precious metal electrodes and to simplify the fabrication process of the Ta2O5 storage capacitor. (C) 1999 American Institute of Physics. [S0003-6951(99)03317-3].
Interconnecting highways
(1999-04-29)
Du, DZ
;
Hwang, FK
;
Xue, GL
;
應用數學系
;
Department of Applied Mathematics
We present the problem of constructing roads of minimum total length to interconnect n highways under the constraint that the roads can intersect each highway only at one point in a designated interval which is a line segment. We present a set of optimality conditions for the problem and show how to construct a solution to meet this set of optimality conditions.
Online glint noise identification for tracking manoeuvring targets
(1999-04-29)
Wu, WR
;
Wu, KG
;
資訊工程學系
;
電信工程研究所
;
Department of Computer Science
The glint noise arising from a radar tracking system exhibits non-Gaussian statistics. Pure noise data, usually not available in online applications, are required in conventional glint identification methods. A new algorithm is presented for online glint identification using radar measurement data. Simulations show that the identified results, of the proposed algorithm using measurement data are close to those using pure noise data.
The speed-controlled interpolator for machining parametric curves
(1999-04-30)
Yeh, SS
;
Hsu, PL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Modern CNC systems are designed with the function of machining arbitrary parametric curves to save massive data communication between CAD/CAM and CNC systems and improve their machining quality. Although available CNC interpolators for parametric curves generally achieve contouring position accuracy, the specified feedrate, which dominates the quality of the machining processes, is not guaranteed during motion. Recently, some approximation results concerning motion speed have been reported [Shpitalni M, Koren Y, Lo CC. Computer-Aided Design 1994;26(11):832-838; Bedi S, Ali I, Quan N. Trans ASME J Engng Industry 1993;115:329-336; Chou JJ, Yang DCH. Trans. ASME J Engng Industry 1991;113:305-310; Chou JJ, Yang DCH. Trans ASME J Engng Industry 1992;114:15-22]. In this paper, by deriving a compensatory parameter, the proposed interpolation algorithm has significantly improved curve speed accuracy. In real applications, the proposed algorithm results in: (1) constant speed: and (2) specified acceleration and deceleration (ACC/DEC) to meet the feedrate commands. The motion accuracy and feasibility of the present interpolator have been verified with a provided non-uniform rational B-spline (NURBS) example. (C) 1999 Elsevier Science Ltd. Ail rights reserved.
Promotion of phase transformation and single-phase formation in silver-doped Tl-Ba-Ca-Cu-O superconducting thin films
(1999-05-01)
Koo, HS
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Phase transformation and physical characteristics of the spray-pyrolyzed Tl-Ba-Ca-Cu-O superconducting films with 3 mol% silver dopant have been studied using electrical resistivity, x-ray diffraction, and scanning electron microscopy. The major phase formed in the resultant film, annealed at a temperature of 885 degrees C for 3 min, was found to be the nearly single-phase, high-T-c, Tl2Ba2Ca2Cu3Oy (Tl-2223), The multiple phase of Tl2Ba2Ca2Cu3Oy and TlBa2Ca2Cu3Oy (Tl-1223) appeared at annealing temperatures lower and higher than 885 degrees C. It was also observed that Ag dopant effectively reduces normal resistivity at 300 K and enhances the phase transformation of single-rrl-layer Tl-1223 to double-Tl-layer Tl-2223 phases and further helps to form the nearly single-phase Tl-2223 within a short duration. Critical transition temperature (T-c,T-zero) and current density (J(c), 77 K, 0 Tesla) of the best resultant film were shown to be 123 K and 5.7 X 10(4) A/cm(2), respectively.
Adsorption behavior of iron-cyanide onto gamma-Al2O3 interface: A coagulation approach
(1999-05-01)
Cheng, WP
;
Huang, CP
;
Pan, JRS
;
環境工程研究所
;
Institute of Environmental Engineering
Ferrocyanide and ferricyanide ions have strong coagulation ability in a natural water system due to their high valences. Studies with aluminum oxide turbid waters showed significant differences in coagulation between simple ions (Cl-, SO42-, Fe(CN)(6)Fe3-(CN)(6)(4-)) and other species (H2PO4-) that interact chemically with the oxide surface. The evidence suggested that the adsorption of ferrocyanide and ferricyanide on aluminum oxide surface is an outer-sphere reaction. The linear relationship between the logarithm of the significant coagulation concentration and Schultz-Hardy ratios indicated that the coagulation obeyed the DLVO rule. Therefore, it is concluded that the coagulation of aluminum oxide by ferrocyanide and ferricyanide is essentially caused by compression of the electric double layer rather than by charge neutralization. (C) 1999 Academic Press.
The CVD growth of Cu films using H-2 as carrier gas
(1999-05-01)
Lin, PJ
;
Chen, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Copper chemical vapor deposition from Cu(hexafluoroacetylacetonate)trimethyl-vinylsilane (Cu(hfac)TMVS) was studied using a low pressure chemical vapor deposition system of a cold wall vertical reactor. The Cu films deposited using H-2 as a carrier gas revealed no impurities in the films within the detection limits of Auger electron spectroscopy and x-ray photoelectron spectroscopy. Using hydrogen as a carrier gas, the hydrogen not only acts as a reducing agent, but also reacts with the residual fragment of precursor. As a result, using H-2 as a carrier gas for Cu(hfac)TMVS resulted in Cu films of lower resistivity, denser microstructure and faster deposition rate than using Ar or N-2 as the carrier gas. Moreover, we found that N-2 plasma treatment on the substrate surface prior to Cu deposition increased the deposition rate of Cu films.