Browsing by Issue Date, starting with "1997-11-15"

Now showing 1 - 20 of 83248

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.
Integrating order release control with due-date assignment rules
(1997-12-01)
Tsai, CH
;
Chang, GT
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This study integrates order release control methods with due-date assignment rules and assesses its impact on the accuracy of inter-operation time estimation and performance of due-date assignment. The assessment is made by using an experimental design with three due-date assignment rules, three scheduling rules and three order release models. The three order release models are: (1) Basic model, in which three due-date assignment rules consider the order arrival time as the order release time; (2) Control model, in which three due-date assignment rules integrate with the order release control method developed here; and (3) Adjustment model, in which the control model integrates with the order release control adjustment developed here. Simulation results in this study indicate that integrating the order release control method with due-date assignment rules will significantly enhance not only the accuracy of interoperation time estimation, but also the performance of due-date assignment rules.
Broadband service creation and operations
(1997-12-01)
Lin, YD
;
Lin, YT
;
Chen, PN
;
Choy, MM
;
資訊工程學系
Three challenges for deploying broadband services are the time-consuming process of service creation, the interoperability over heterogeneous platforms, and the gap between the needs of service management and the functionalities of network management. In this article we describe a methodology to attack the first two challenges, namely, to simplify the process of service creation and provide a platform-independent framework for service operations. A set of broadband service-independent building blocks (SIBs) are designed and used to create and customize SIB graphs for broadband services. During service running time, the service agent interprets a SIB graph and executes SIB procedures which are all downloaded from the service provider. Web, Java, and CORBA are the technological elements of this methodology. Two examples, video conferencing and video on demand, are given to demonstrate the feasibility of this approach.
Generating fuzzy rules from relational database systems for estimating null values
(1997-12-01)
Chen, SM
;
Yeh, MS
;
資訊工程學系
;
Department of Computer Science
This paper presents a new algorithm for constructing fuzzy decision trees from relational database systems and generating fuzzy rules from the constructed fuzzy decision trees. We also present a method for dealing with the completeness of the constructed fuzzy decision trees. Based on the generated fuzzy rules, we also present a method for estimating null values in relational database systems. The proposed methods provide a useful way to estimate null values in relational database systems.
An exact analysis of an asymmetric polling system with mixed service discipline and general service order
(1997-12-01)
Hwang, LC
;
Chang, CJ
;
電信工程研究所
;
電信研究中心
;
Institute of Communications Engineering
This paper derives the exact mean waiting time fur an asymmetric polling system with general service order and mixed service discipline. The mixed sen ice discipline means that the service discipline of each stage (a turn in the service order sequence) for the same station can be gated or exhaustive. The general service order denotes that each station can be polled more than once in a polling cycle. We use the mean age and the mean excess of a cumulative time to obtain the mean waiting times fur stages and stations, where the cumulative time for a stage is defined as the total arrival time period of all customers that are served at one visit of the server to the stage. The accuracy of our analysis is verified by comparisons with previously published results and simulation results. We also use a genetic algorithm (GA) to search for an optimal pattern of service order and service discipline For the asymmetrical polling system. The results of the paper can be applied to the design of computer communication networks with polling schemes. (C) 1997 Elsevier Science B.V.
Two-phase heat transfer characteristics for R-22/R-407C in a 6.5-mm smooth tube
(1997-12-01)
Wang, CC
;
Chiang, CS
;
機械工程學系
;
Department of Mechanical Engineering
Two-phase friction and heat transfer characteristics for R-22/R-407C inside a 6.5-mm smooth tube are reported in this study, The hear transfer results for G = 100 and 400 kg/m(2) s were reported in the present study, and the adiabatic frictional pressure drop was recorded in the range of 100 to 700 kg/m(2) s, It is found that the development of flow pattern for R-407C Falls behind R-22. This may explain the lower pressure drops for R-407C. The major heat transfer mechanism at low mass flux is nucleate boiling, and virtually becomes the convective evaporation as mass flux increase to G = 400 krg/m(2) s, Meanwhile, the reduction of heat transfer coefficients for R-407C mixtures are especially profound at low mass flux, and The reduction of heat transfer coefficient decreases with the increase of mass flux. (C) 1997 by Elsevier Science Inc.