Browsing by Issue Date, starting with "1998-05-02"

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管管要結婚新娘卅二
(1998-05-02)
江中明
69歲詩人風采擄獲33歲「幼菁」的心紫竹發青芽娶得小嬌娘
(1998-05-02)
陳文芬
管管 17日迎娶梁幼菁
(1998-05-04)
李蓮珠
Far-field emission narrowing effect of microdisk lasers
(1998-05-04)
Lee, TD
;
Cheng, PH
;
Pan, JS
;
Tsai, RS
;
Lai, Y
Far-field intensity distribution of semiconductor microdisk lasers is experimentally measured and the emission angle is found to be much smaller than that of a planar source with the same near-held width. In fact the emission angle is determined mainly by the disk radius instead of the disk thickness. A scalar diffraction theory in the cylindrical coordinate is developed to explain such an emission-angle-narrowing phenomenon and numerical calculation based on a vectorial diffraction theory is carried out to explain the measured polarization state. (C) 1998 American Institute of Physics.
林文義結了又離離了又合
(1998-05-04)
陳文芬
文藝雅集辦桌
(1998-05-04)
潘罡
五四獎創新文學舞台
(1998-05-04)
江中明
Transient heat-transfer phenomenon of two-dimensional hyperbolic heat conduction problem
(1998-05-08)
Wu, JP
;
Shu, YP
;
Chu, HS
;
機械工程學系
;
Department of Mechanical Engineering
This article presents a numerical analysis of the two-dimensional hyperbolic heat conduction problem in an anisotropic medium under a point heat source with different boundary conditions. A simple model has been developed to solve the anisotropic problem. In this analysis, the second-order total variation diminishing (TVD) scheme is employed to solve this problem. The effects of boundary conditions and anisotropy on the thermal wave induced by different types of heat sources in the medium are examined in detail. The results show that the transient behavior of the propagation of the two-dimensional thermal wave is much more complicated than that of the one-dimensional thermal wave due to a circular wave formed to propagate uniformly in all directions, reflections by boundaries, interaction with each other, and serious discontinuity on the wavefront.
兩岸詩人下月華山論詩
(1998-05-08)
江中明
The hidden algebraic structure of the Kaup-Broer hierarchy
(1998-05-08)
Shaw, JC
;
Tu, MH
;
應用數學系
;
Department of Applied Mathematics
In this paper, we investigate the conformal algebra associated with the coupled Kaup-Broer hierarchy which is obtained from the coupled AKNS hierarchy by gauge transformation. We find that the algebraic structure hidden behind the coupled Kaup-Broer hierarchy can be revealed after mapping the Lax operator of the coupled Kaup-Broer hierarchy to a Yajima-Oikawa-type Lax operator. Furthermore, we show that the second Hamiltonian structure of the coupled Kaup-Broer hierarchy can be simplified by factorizing the Lax operator in multiplicative form and thus obtain the free-field realization of the associated algebras.
Eight-channel bidirectional WDM add/drop multiplexer
(1998-05-14)
Ho, KP
;
Liaw, SK
;
光電工程學系
;
Department of Photonics
The authors propose and demonstrate an eight-channel reconfigurable bidirectional wavelength division multiplexed (WDM) add-drop multiplexer in which all channels can be added/dropped independently in either direction. The performance of the bidirectional WDM add/drop multiplexer is experimentally studied for a data rate of 10Gbit/s per channel, providing an overall capacity of 80Gbit/s. It is found that the performance of the add/drop multiplexer is not degraded by a backward propagating signal.
Design and analysis of delay control for CBR services in ATM networks
(1998-05-15)
Chen, YC
;
Chan, CT
;
Hu, SC
;
資訊工程學系
;
Department of Computer Science
Asynchronous transfer mode (ATM) networks are designed to provide end-to-end transport of user data via virtual connections with specified quality of services (QOS), which is expected to be satisfied through effective traffic control mechanisms. This paper presents an adaptive delay-jitter control (ADJC) method that guarantees the delay bounds of constant bit rate (CBR) services in ATM networks. Our proposed method is based on a node-by-node time-frame scheme. Through both mathematical derivation and simulation, we have demonstrated that ADJC features a significant improvement over existing approaches in jitter delay, which can be reduced to one time-frame from end-to-end for CBR traffic. Simulation results have shown that CBR services receive satisfactory delay performance using our approach. (C) 1998 Elsevier Science B.V.
Scanning tunneling microscopy observation of surface reconstruction of Si(100) during chemical vapor deposition from Si2H6
(1998-05-15)
Lin, DS
;
物理研究所
;
Institute of Physics
This study employs real-time high-temperature scanning tunneling microscopy to examine the evolution of the surface atomic structure of Si(100) during homoepitaxy by chemical vapor deposition at 625 degrees C. At the initial stage, a (2 x n) structure is gradually formed, and the growth mode is pure step flow, followed by double step flow after a single-domain surface is obtained due to faster step advance of S-B than S-A. As growth proceeds, areas with c(4 x 4) symmetry appear, grow, and eventually cover the entire surface. (C) 1998 Elsevier Science B.V. All rights reserved.
Correlation of supercritical fluid extraction with supercritical fluid chromatography in aqueous matrixes
(1998-05-15)
Yu, T
;
Luo, SK
;
Chen, SJ
;
應用化學系
;
Department of Applied Chemistry
A mathematical model is presented for correlating supercritical fluid chromatography (SFC) in aqueous stationary phases with supercritical fluid extraction (SFE) in aqueous matrixes. A solar coaxial countercurrent chromatography apparatus was used for the SFC and SFE experiments. The SFE extraction vessel, i.e., the column for SFC, was mathematically divided into limited layers. During extraction, each layer was considered to undergo a chromatographic process. The plate heights of all the layers were regarded equal throughout the column because pressure drops in the system were negligible. Each layer's chromatographic capacity factor and peak width were calculated using true SFC experimental data, and the sum of all these peak distributions as a function of time gave the extraction efficiency. Accordingly, the SFE analyte recovery curve could be simulated using SFC data and this model. Since SFC operations are more straightforward than SFE operations, SFE optimization may be more easily achieved using this mathematical correlation. The simulated analyte data of large capacity factors matched the experimental results very well. Deviations gradually became greater as analyte capacity factors were decreased. A rationale is proposed that satisfactorily interprets this deviation trend.
Growth mode in Si(100)-(2x1) epitaxy by low-temperature chemical-vapor deposition
(1998-05-15)
Wu, PH
;
Lin, DS
;
物理研究所
;
Institute of Physics
This study investigates the growth processes of Si on Si(100)-(2x1) during ultrahigh vacuum chemical vapor deposition using disilane as the source gas. The evolution of surface morphology and atomic ordering during growth at temperatures between 300 and 600 degrees C is examined in real time by high-temperature scanning tunneling microscopy. Directly imaging various growth kinetic processes, such as pure step-flow growth, double step-flow growth, two-dimensional nucleation growth, and surface passivation at different substrate temperature ranges clearly illustrates the growth mechanisms for the model chemical vapor deposition growth system and provides interesting comparison with results of Monte Carlo simulations and those of solid phase molecular-beam epitaxy. [S0163-1829(98)05619-7].
Resonant ultrafast nonlinear optics of bulk semiconductors under electric-field modulation
(1998-05-15)
Lai, CM
;
Meng, HF
;
電子物理學系
;
物理研究所
;
Department of Electrophysics
In bulk direct-band-gap semiconductors the ground state of a (photoexcited) electron-hole system is normally an exciton gas, instead of an electron-hole plasma, as long as the carrier density is not too large. We demonstrate theoretically that, in the presence of an electric-field modulation, the energy of the plasma is decreased due to the induced charge-density fluctuation. As a results, the plasma becomes the ground state at much lower carrier densities, implying that the critical carrier density for the transition between these two states can be reduced. This transition provides a mechanism of nonlinear optics for bulk direct-band-gap semiconductors with picosecond relaxation time, large nonlinearity, and low pump intensity.
Computer-generated holographic diffuser for color mixing
(1998-05-15)
Chao, W
;
Chi, S
;
Wu, CY
;
Kuo, CJ
;
光電工程學系
An iterative algorithm for multiple incoming wavelengths is proposed to design a computer-generated holographic diffuser with the features of high light utilization efficiency and uniform color mixing. The amplitude transmittance of this computer-generated holographic diffuser is constant, while the phase transmittance consists of multiple phase levels. This diffuser is designed according to the Fraunhofer diffraction theory and can uniformly spread the different input light at the same time. The simulation results show that over 88% average far field amplitude transmission efficiency is achieved for each input light and the output uniformity is within 12.4%. (C) 1998 Elsevier Science B.V. All rights reserved.
Specification, validation, and verification of time-critical systems
(1998-05-15)
Shieh, SP
;
Chen, JN
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a new formalism, named the Timed Communicating Finite State Machine (Timed CFSM), for specifying and verifying time-critical systems. Timed CFSM preserves the advantages of CFSM, such as the ability to express communication, synchronization and concurrency in computer systems. A given time-dependent specification can be formalized as a Timed CFSM, from which the reachability graph is constructed to verify the correctness of the specification. To cope with the space explosion problem from which all reachability analysis methods suffer, we propose a space reduction algorithm to meet the space constraint of the verification environment. (C) 1998 Elsevier Science B.V.
一種想得都得不到的病
(1998-05-17)
管管
管管娶親人生七十又逢春忘年絕配普天同羨
(1998-05-18)
賴素鈴