Browsing by Issue Date, starting with "1999-08-07"

Now showing 1 - 20 of 80379

給小兒管領風聖旨
(1999-08-07)
管管
管領風上奏父皇章
(1999-08-07)
管領風
Phase separation process in poly(epsilon-caprolactone)-epoxy blends
(1999-08-10)
Chen, JL
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
Phase separation process in poly(epsilon-caprolactone)-epoxy blends (PCL-epoxy) cured by 4,4'-diaminodiphenyl sulfone (DDS) was investigated by OM and SEM. The blend compositions higher than the critical point exhibit macrophase separation by the spinodal decomposition (SD) mechanism of the epoxy and results in the epoxy particles being dispersed in the matrix. These epoxy particles grow larger gradually and connect to each other to give macrophase epoxy domains with irregular shape. After that, two more stages of microphase separations bake place via a nucleation and growth (NG) mechanism and result in smaller epoxy particles being dispersed in the matrix. Blend compositions lower than the critical point exhibit the SD or NG mechanisms of PCL, but the microphase separation is observed only within the epoxy matrix. These phase separation mechanisms can be illustrated successfully by the phase diagram constructed by the spinodal and binodal curves. Hydrogen bonding between protons from the epoxy with carbonyls from PCL has been investigated by FTIR. The mixing free energy reduction by the hydrogen bonding can contribute to the LCST behavior rather than the UCST behavior predicted by the Flory-Huggins equation based on only nonpolar interactions.
救救地球,少買幾件衣裳
(1999-08-14)
管管
On the generation of higher order numerical integration methods using lower order Adams-Bashforth and Adams-Moulton methods
(1999-08-15)
Chiou, JC
;
Wu, SD
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, a new explicit numerical integration method is proposed. The proposed method is based on the relationship that m-step Adams-Moulton method is the linear convex, combination of (m - 1)-step Adams-Moulton and m-step Adams-Bashforth methods with a fixed weighting coefficient. By examining the order of accuracy and stability regions, we conclude that the present method is superior to the traditional Adams-Bashforth-Moulton predictor-corrector method. A simple harmonic oscillator problem is used to demonstrate the efficiency of the proposed method. (C) 1999 Elsevier Science B.V. All rights reserved.
Synthesis, characterization, thermal and flame-retardant properties of silicon-based epoxy resins
(1999-08-15)
Hsiue, GH
;
Wang, WJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A new silicon-containing oxirane triglycidyl phenyl silane oxide (TGPSO) and its corresponding silicon-containing epoxy resins are synthesized and characterized. The activation energies of TGPSO curing reaction with various curing agents, including 4,4-diaminodiphenylmethane, 4,4-diaminodiphenylsulfone, and dicyanodiaminde, are found to be 180, 196.5, and 154 kJ/mol. The curing reaction of TGPSO with diamines is determined to be a first-order reaction through means of Arrhenius plots. The introduction of the silicon-containing group results in higher curing reactivity. This silicon-containing resin possesses higher char yield as well as higher limiting oxygen index (LOI = 35) than the commercial epoxy resins, confirming the usefulness of these silicon-containing epoxy resins as flame retardants. Char yields and LOI measurements demonstrate that incorporating silicon into epoxy resins is able to improve their flame retardancy. (C) 1999 John Wiley & Sons, Inc.
Analysis of a general limited scheduling mechanism for a distributed communication system
(1999-08-17)
Hwang, LC
;
Chang, CJ
;
電信工程研究所
;
電信研究中心
;
Institute of Communications Engineering
This paper studies an alternative scheduling mechanism of general limited service discipline for a distributed communication system, where the distributed system has a modular architecture and the module has tasks in the queue. We successfully analyze the system by way of imbedded Markov chains acid use a recursive method to derive the mean waiting time of task. The arrival processes for modules are assumed to be Poisson processes; the service time of a task in queues and the walking time between queues are assumed to be generally distributed. We also presents an optimal-pattern design of the general limited scheduling mechanism for the distributed communication system via a genetic algorithm. A distributed communication system, if designed with the general limited scheduling mechanism and its optimal pattern, can be flexible to meet the system requirements as much as possible. (C) 1999 Elsevier Science B.V. All rights reserved.
Tunable semiconductor laser with liquid crystal pixel mirror in grating-loaded external cavity
(1999-08-19)
Pan, CL
;
Tsai, SH
;
Pan, RP
;
Sheu, CR
;
Wang, SC
The wavelength of a commercial red pointer laser diode has been tuned over 4nm digitally in 0.2nm steps with a folded telescopic gating loaded external cavity incorporating a liquid crystal pixel mirror. The sidemode-suppression ratio of the laser was better than 20dB throughout this range.
PP/PA6 blends compatibilized by poly(oxypropylene)amide-functionalized PP.
(1999-08-22)
Lin, JJ
;
Young, MY
;
Tseng, FP
;
Chang, FC
;
應用化學系
Synthesis of elvirol methyl ether.
(1999-08-22)
Ho, TL
;
Ho, MF
;
應用化學系
;
Department of Applied Chemistry
Preparation and epoxy curing of novel Mannich bases.
(1999-08-22)
Lin, JJ
;
Lin, SF
;
Tseng, FP
;
Chang, FC
;
應用化學系
Observation of abnormal capacitance-frequency behavior in In0.12Ga0.88As/GaAs p-i-n superlattice grown at low temperature
(1999-08-23)
Chen, JF
;
Wang, JS
;
Wang, PY
;
Wong, HZ
;
電子物理學系
Capacitance-frequency measurement is used to study In0.12Ga0.88As/GaAs p-i-n superlattice, with superlattice layer grown at 300 degrees C by molecular-beam epitaxy. Three traps are observed, and their parameters are consistent with those obtained from deep-level transient spectroscopy. Among these three traps, the trap (E-a = 0.45 +/- 0.02 eV, sigma = 6 +/- 4x10(-17) cm(2)) shows an abnormal increase of capacitance with increasing frequency, similar to that observed from the 0.66 eV trap in low-temperature grown GaAs p-i-n structure, suggesting that it is created by the low-temperature growth and is a generation-recombination center. This result also shows that the capacitance-frequency measurement is effective in studying the generation-recombination centers. (C) 1999 American Institute of Physics. [S0003-6951(99)01434-5].
Synthesis and relationships between the nonlinear optical and holographic properties of dual functional azocarbazole chromophores based on photorefractive polymers
(1999-08-24)
Chang, CJ
;
Whang, WT
;
Hsu, CC
;
Ding, ZY
;
Hsu, KY
Two kinds of dual functional carbazole-based chromophores are synthesized to enhance the photorefractive (PR) performance of the polymers by attaching the electron-donating and electron-accepting groups with a diazo bridge on the 3- and 6-positions of the N-ethylcarbazole. The electron-donating group is N,N-diethanol aminophenyl. The electron-accepting group is either p-nitrophenyl or 5-nitrothiazole. The peak maximum of the UV/vis absorption spectra of the 5-nitrothiazole-containing chromophore PANTAC at 535 nm is longer than that of the p-nitrophenyl-containing PANPAC at 477 nm. Both chromophores exhibit a large first hyperpolarizability in the hyper-Rayleigh scattering experiment due to the extended chain length. The first hyperpolarizability of PANTAC is 1100 x 10(-30) esu, almost the double of that of PANPAC (590 x 10(-30) esu). The diffraction efficiencies of both polymers are the function of the film thickness and the laser beam wavelength with a maximum eta(max) at a thickness d(max) between 15 and 23 mu m Surprisingly, the PANPAC-based PR polymer reveals a higher maximum diffraction efficiency (eta(max)) and better fringe of the stored holograms than the PANTAC-based PR polymer does. Both the PR polymers written/read by the green/red laser have greater eta(max) values than those written/read by the green/green laser. These phenomena are related to the balance between absorption and transmission of the laser beam through the PR polymer.
Frame-based priority scheduling in hybrid IP/ATM networks
(1999-08-25)
Chen, YC
;
Hu, SC
;
Chan, CT
;
Lee, CL
;
資訊工程學系
The exploding growth of World Wide Web applications in recent years has overwhelmed the internet with multimedia traffic. A future performance concern is to keep pace with the quickly growing bandwidth requirements. IP over ATM is a way to relax such requirements. It provides a hybrid approach to support both layer 3 software forwarding and layer 2 ATM hardware switching. A switched virtual connection may be suitable for traffic involving large data transfers and QoS provision like Guarantee Service (GS) applications. In the hybrid IP/ATM networks, the packet-level instead of the cell-Level behavior is the relevant measure of performance. In this paper, we propose a so-called Frame-based Priority Scheduling (FBPS) algorithm far GS applications. FBPS focuses on the packet-level performance while transmitting based on cells. The most attractive feature of FBPS is its simplicity. We provide a systematic analysis of FBPS scheduler and derive the bound on its fairness when the how traffic is shaped by a leaky bucket. It shows that FBPS is competitive with certain complex scheduling disciplines such as PGPS. We also verify our analytical bounds by simulation. (C) 1999 Elsevier Science B.V. All rights reserved.
Cantori barriers in the excitation of a diatomic molecule by chirped pulses
(1999-08-28)
Lin, JT
;
Jiang, TF
;
物理研究所
;
Institute of Physics
We present a nonlinear dynamical study of a diatomic molecule under the interaction of chirped pulses. The step-like dissociation probability with respect to the initial vibrational states reflects the cantori barriers during the excitation process. The correspondence between classical and quantum cantori barriers is shown through classical phase trajectory and quantum Husimi distribution function. According to the results, the quantum suppression of classical dissociation in molecular excitation by chirped pulse disappears at some field parameters.
喘月
(1999-08-29)
管不着
三進桃花源所以暗戀
(1999-08-31)
管管
Cost-effective VLSI architectures and buffer size optimization for full-search block matching algorithms
(1999-09-01)
Yeh, YH
;
Lee, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents two efficient very large scale integration (VLSI) architectures and buffer size optimization for full-search block matching algorithms. Starting from an overlapped data how of search area, both systolic- and semisystolic-array architectural solutions are derived. By means of exploiting stream memory banks, not only input/output (I/O) bandwidth can be minimized, but also processor element efficiency can be improved, In addition, the controller structure for both solutions are very straightforward, making them very suitable for VLSI implementation to meet computational requirements. Moreover, by exploring the dependency graph, we focus on the problem of reducing the internal buffer size under minimal I/O bandwidth constraint to derive guidelines on reducing redundant internal buffer as well as to achieve area-efficient VLSI architectures. Simulation results show that, for N = P = 16 (N is the reference block size and P is the search range), I/O bandwidth can be reduced by 2.4 times, while buffer size increases less than 38%. Two prototype chips for N = P = 16 have been designed and fabricated. Test results show that clock rate can be up to 90 MHz, implying that more than 87.9-K motion vectors per second can be achieved to meet real-time requirements specified in MPEG-2 MP@ML coding standard.
Bifurcation of fundamental Gaussian modes in Kerr-lens mode-locked lasers
(1999-09-01)
Wei, MD
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
We propose that more than one spatial fundamental Gaussian mode may occur in concentric and confocal resonators under persisting nonlinear effect. Extensively studying the influence of the resonator's parameters in a Kerr-lens mode-locked resonator, pitchfork bifurcation results in more symmetrical configurations, and saddle-node bifurcation appears as the symmetry being broken. From the properties of bifurcation, we suggest that the equal-arm and near-confocal resonator is suitable for the emergence of bistability in Kerr-lens mode-locked lasers. (C) 1999 Elsevier Science B.V. All rights reserved.
A high-temperature thermodynamic model for metalorganic vapor phase epitaxial growth of InGaN
(1999-09-01)
Ou, J
;
Pan, YC
;
Lee, WH
;
Shu, CK
;
Lin, HC
A thermodynamic analysis tailored with a high-temperature parameter was performed for metalorganic vapor phase epitaxial (MOVPE) growth of InxGa1-xN alloys. Accordingly, a series of InGaN samples were prepared under various input In flow rates and growth temperatures. Theoretical results indicate that the In solid concentration tends to increase with increasing In flow rate and with decreasing temperature, whereas the metal droplets form more easily on the surface at lower growth temperatures and higher In fluxes, which are in good agreement with our experimental data.