Browsing by Issue Date, starting with "1997-11-10"

Now showing 1 - 20 of 83253

Subsonic solutions of hydrodynamic model for semiconductors
(1997-11-10)
Yeh, LM
;
交大名義發表
;
應用數學系
;
National Chiao Tung University
;
Department of Applied Mathematics
This paper is concerned with the existence and uniqueness of the steady-state solution of hydrodynamic model for semiconductor devices. Boundary conditions are prescribed by vorticity on inflow boundary as well as by electron density, temperature, and normal component of electron velocity on whole boundary. If the ambient temperature is large, and if both vorticity on inflow boundary and the variation of density on boundary are small, a unique subsonic solution exists. (C) 1997 by B.G. Teubner Stuttgart-John Wiley & Sons Ltd.
Performances and characteristics of a prototype symmetric hybrid adjustable phase undulator
(1997-11-11)
Hwang, CS
;
Chang, CH
;
Fan, TC
;
Lin, FY
;
Wang, C
In this work, we construct and measure a prototype symmetric Hybrid Adjustable Phase Undulator (HAPU) with nine poles to compare phase change and gap change in terms of their features and performances. HAPU can also provide the different characteristics between the pure and hybrid adjustable phase undulator. The HAPU has been installed in the Synchrotron Radiation Research Center (SRRC) storage ring to test the performance of the beam dynamics and photon flux behavior. A three-orthogonal Hall probe and a long-loop-coil measurement system are also implemented to take the field measurements. The multipole field and electron trajectory correction are made by shimming, the magic finger, and the active end pole coil corrector. After the field measurements, the vertical integral strength of HAPU is markedly smaller than that of the Hybrid Adjustable Gap Undulator (HAGU) and confirm that no obvious distinction arises between HAPU and HAGU in terms of the spectrum flux. The electron beam dynamic performance in the storage ring indicates that the vertical tune shift of HAPU is three times smaller than that of HAGU. Meanwhile, the energy dynamic tuning with the digital global feedback turned on, the photon position and flux in the bending chamber beam line is invariant. In addition, the injection efficiency remains unaffected at any phase position and the electron beam lifetime does not change when HAPU is in the dynamic tuning.
The computational complexity of the reliability problem on distributed systems
(1997-11-14)
Lin, MS
;
Chen, DJ
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
The reliability of a distributed program in a distributed computing system is the probability that a program which runs on multiple processing elements and needs to communicate with other processing elements for remote data files will be executed successfully. This reliability varies according to (1) the topology of the distributed computing system, (2) the reliability of the communication links, (3) the data files and program distribution among processing elements, and (4) the data files required to execute a program. This paper shows that solving this reliability problem is NP-hard even when the distributed computing system is restricted to a series-parallel, a 2-tree, a tree, or a star structure. (C) 1997 Elsevier Science B.V.
The computational complexity of the reliability problem on distributed systems
(1997-11-14)
Lin, MS
;
Chen, DJ
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
The reliability of a distributed program in a distributed computing system is the probability that a program which runs on multiple processing elements and needs to communicate with other processing elements for remote data files will be executed successfully. This reliability varies according to (1) the topology of the distributed computing system, (2) the reliability of the communication links, (3) the data files and program distribution among processing elements, and (4) the data files required to execute a program. This paper shows that solving this reliability problem is NP-hard even when the distributed computing system is restricted to a series-parallel, a 2-tree, a tree, or a star structure. (C) 1997 Elsevier Science B.V.
落日
(1997-11-14)
管管
Resonant optical nonlinearity of conjugated polymers
(1997-11-15)
Chang, MC
;
Meng, HF
;
物理研究所
;
Institute of Physics
When the energy of a pump wave is in resonance with the exciton creation energy, the electric susceptibility of a conjugated polymer in response to the probe wave is altered by the exciton gas. In this paper we calculate the dependence of this change on the exciton populations by the equation of motion (EOM) method. The magnitude of optical nonlinearity is also influenced by ambient temperature, by the extent of exciton wave functions, and by the strength of electron-electron interaction. All of these factors can be easily incorporated in the EOM approach systematically. Using the material parameters for polydiacetylene, the optical Ken coefficient n(2) obtained is about 10(-8) cm(2)/W, which is close to experimental value, and is four orders of magnitude larger than the value in nonresonant pump experiments.
Bayesian analysis of growth curves with AR(1) dependence
(1997-11-15)
Lee, JC
;
Hsu, YL
;
統計學研究所
;
Institute of Statistics
In this paper we consider Bayesian analysis of the generalized growth curve model when the covariance matrix Sigma = sigma(2)C where C=(rho(i-j)), sigma(2) > 0 and -1 < rho < 1 are unknown. We consider both parameter estimation and prediction of future values. Results are illustrated with real and simulated data. (C) 1997 Elsevier Science B.V.
Resonant optical nonlinearity of conjugated polymers
(1997-11-15)
Chang, MC
;
Meng, HF
;
物理研究所
;
Institute of Physics
When the energy of a pump wave is in resonance with the exciton creation energy, the electric susceptibility of a conjugated polymer in response to the probe wave is altered by the exciton gas. In this paper we calculate the dependence of this change on the exciton populations by the equation of motion (EOM) method. The magnitude of optical nonlinearity is also influenced by ambient temperature, by the extent of exciton wave functions, and by the strength of electron-electron interaction. All of these factors can be easily incorporated in the EOM approach systematically. Using the material parameters for polydiacetylene, the optical Ken coefficient n(2) obtained is about 10(-8) cm(2)/W, which is close to experimental value, and is four orders of magnitude larger than the value in nonresonant pump experiments.
Picosecond responses of low-dosage arsenic-ion-implanted GaAs photoconductors
(1997-11-17)
Lin, GR
;
Pan, CL
;
光電工程學系
;
Department of Photonics
Ultrafast optoelectronic characteristics of GaAs implanted with 200 keV arsenic ions at dosage as low as 10(13) ions/cm(2) are reported. Ultrashort photoexcited carrier lifetimes of 0.23+/-0.02, 0.87+/-0.02, and 3+/-0.2 ps were determined for as-implanted, rapid thermal annealing (RTA) (600 degrees C for 30 s) and furnace-annealed (600 degrees C for 30 min) arsenic-ion-implanted GaAs or GaAs:As+, respectively. The switching response of photoconductive switches (PCSs) fabricated on the latter two materials were similar to 3 and 8 ps, respectively. The leakage current of the PCS fabricated on furnace-annealed sample was as low as 30 nA. The breakdown fields exceeded 150 (instrument-limited) and 90 kV/cm for furnace-and RTA-annealed samples, respectively. The optical responsivity of low-dosage arsenic-implanted GaAs photoconductive switch can be as high as 0.01 A/W. This also compared favorably with the same device made on state-of-the-art photoconductor such as molecular-beam epitaxy grown GaAs at low temperatures. (C) 1997 American Institute of Physics.
鏡子
(1997-11-17)
管管
荷案
(1997-11-18)
管管
春藤
(1997-11-20)
管管
Maximal independent sets in graphs with at most one cycle
(1997-11-27)
Jou, MJ
;
Chang, GJ
;
應用數學系
;
Department of Applied Mathematics
In this paper, we determine the largest number of maximal independent sets among all connected graphs of order n, which contain at most one cycle. We also characterize those extremal graphs achieving this maximum value. As a consequence, the corresponding results for graphs with at most one cycle but not necessarily connected are also given.
Resolution studies on counter-current chromatography using supercritical fluid carbon dioxide
(1997-11-28)
Yu, T
;
Chen, YH
;
應用化學系
;
Department of Applied Chemistry
Counter-current chromatography (CCC) is a form of Liquid-liquid partition chromatography. It requires two immiscible solvent phases; the stationary phase is retained in thr separation column, generally by centrifugal force, while the mobile phase is eluted. We recently replaced the mobile phase with supercritical fluid carbon dioxide (SF CO2). Since the solvent strength of SF CO2 can be varied by changing the temperature and pressure of the system, separation adjustments are thus more versatile. We investigated the pressure and temperature effects on resolution using water and low-carbon alcohol mixtures as the stationary phases. It was demonstrated that these special properties of SF CO2 were indeed beneficial to the optimization of separations. In addition, the phase retention ratio was examined in terms of separation resolution. The results appeared very similar to those obtained from conventional traditional CCC. This study should be helpful for the future development of SF applications in CCC. (C) 1997 Elsevier Science B.V.
Resolution studies on counter-current chromatography using supercritical fluid carbon dioxide
(1997-11-28)
Yu, T
;
Chen, YH
;
應用化學系
;
Department of Applied Chemistry
Counter-current chromatography (CCC) is a form of Liquid-liquid partition chromatography. It requires two immiscible solvent phases; the stationary phase is retained in thr separation column, generally by centrifugal force, while the mobile phase is eluted. We recently replaced the mobile phase with supercritical fluid carbon dioxide (SF CO2). Since the solvent strength of SF CO2 can be varied by changing the temperature and pressure of the system, separation adjustments are thus more versatile. We investigated the pressure and temperature effects on resolution using water and low-carbon alcohol mixtures as the stationary phases. It was demonstrated that these special properties of SF CO2 were indeed beneficial to the optimization of separations. In addition, the phase retention ratio was examined in terms of separation resolution. The results appeared very similar to those obtained from conventional traditional CCC. This study should be helpful for the future development of SF applications in CCC. (C) 1997 Elsevier Science B.V.
草
(1997-11-30)
管管
Curing behaviour of compatible interpenetrating polymer networks based on epoxy and methacrylated epoxy
(1997-12-01)
Wang, MW
;
Lee, CT
;
Lin, MS
;
應用化學系
;
Department of Applied Chemistry
Compatible interpenetrating polymer networks (IPNs) based on diglycidyl ether of bisphenol A (DGEBA) and methacrylated diglycidyl ether of bisphenol A (MADGEBA) in weight ratios of 100/0, 75/25, 50/50, 25/75 and 0/100 were blended and cured simultaneously by using dicumyl peroxide (DICUP) and hexahydrophthalic anhydride (HHPA) as curing agents. Fourier transform infrared spectroscopy (FTIR) was employed to investigate the intermolecular interactions and functional group changes. Viscosity increases during crosslinking were examined with a Brookfield viscometer. Curing exothermic peaks were studied with differential scanning calorimetry (DSC). The gel fractions of various IPN compositions were measured with a Soxhlet extractor. Samples thus prepared were checked for their compatibility by measuring glass transitions with DSC and damping peaks with rheometric dynamic spectroscopy (RDS). Experimental results revealed that good compatibility between components induced a network interlock, which subsequently resulted in incomplete cure of the IPN materials.
Enhancement of anaerobic digestion of waste activated sludge by alkaline solubilization
(1997-12-01)
Lin, JG
;
Chang, CN
;
Chang, SC
;
環境工程研究所
;
Institute of Environmental Engineering
The performance of an anaerobic digestion fed with waste activated sludge (WAS) pretreated with NaOH was examined The sludge was periodically collected from a municipal wastewater-treatment plant. The laboratory work was run in four I-I semi-continuous anaerobic digestion reactors. Reactor-A was fed with untreated WAS at 1% total solids (TS). The other three reactors, B, C and D, were respectively fed with WAS (1% TS) pretreated with 20 meq/l NaOH, WAS (1% TS) pretreated with 40 meq/l NaOH, and WAS (2% TS) pretreated with 20 meq/l NaOH. The reactors were operated at 35 degrees C at four hydraulic retention rimes - 20, 13, 10 and 7.5 days. The performances of reactors B, C and D, in terms of chemical oxygen demand (GOD), volatile solids (VS) removal, and gas production, were superior to that of reactor A. At a retention time of 10 days, the COD removals of reactors A, B, C and D were 38, 46, 51 and 52%, respectively. The gas productions of reactors B, C and D were, respectively, increased by 33, 30 and 163% over that of reactor A. The sludge dewaterability was examined by capillary suction rime (CST). The dewaterability of digested sludge was improved in reactors B, C and D. Capillary suction of digested sludges gave times in the range 148-389 s, compared with 309-735 s for undigested sludges. (C) 1997 Elsevier Science Ltd.
Handover management for a PCS network
(1997-12-01)
Noerpel, A
;
Lin, YB
;
交大名義發表
;
National Chiao Tung University
A handover is required in wireless personal communications systems when a portable moves from one base station coverage area to another during the course of a conversation. In general, the handover should be completed while the portable is in the overlap region to be successful. This article considers several issues for handover management, handover detection, channel assignment, and radio link transfer.
Multi-response robust design by principal component analysis
(1997-12-01)
Su, CT
;
Tong, LI
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Most previous Taguchi method applications have only addressed a single-response problem. However, more than one correlated response normally occurs in a manufactured product. The multi-response problem has received only limited attention. In this work, we propose an effective procedure on the basis of principal component analysis (PCA) to optimize the multi-response problems in the Taguchi method. With the PCA, a set of original responses can be transformed into a set of uncorrelated components. Therefore, the conflict for determining the optimal settings of the design parameters for the multi-response problems can be reduced. Two case studies are evaluated, indicating that the proposed procedure yields a satisfactory result.