Browsing by Issue Date, starting with "1998-03-05"

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Multigrid computation for curve fitting in the wavelet domain
(1998-03-05)
Ho, WJ
;
Chang, WT
;
電信工程研究所
;
Institute of Communications Engineering
A multi-layer multigrid algorithm for curve fitting in the wavelet domain is presented. This algorithm is achieved by applying a wavelet transform to each grid of the conventional multigrid structure. Using a wavelet transform, the convergent rate in each grid is improved and the total system can converge more quickly.
Adaptive receiver for DS/CDMA communications over impulsive noise channels
(1998-03-05)
Hwang, HC
;
Wei, CH
;
電子工程學系及電子研究所
;
電信研究中心
;
Department of Electronics Engineering and Institute of Electronics
A new adaptive algorithm is proposed for training soft-limiter based correlation receiver in which the direct sequence code division multiple access signals corrupted by impulsive symmetric a-stable noise are demodulated. The new adaptation algorithm allows simpler implementation and faster convergence speed in comparison with the traditional adaptive stochastic gradient-based algorithms.
Electrical properties and crystal structures of (Ba,Sr)TiO3 films and BaRuO3 bottom electrodes prepared by sputtering
(1998-03-09)
Chu, CM
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba,Sr)TiO3 (BST) films were synthesized on BaRuO3 (BRO) using radio-frequency magnetron sputter deposition. Conductive (similar to 1 m Omega cm) BRO layers of (110) texture were produced at a deposition temperature T-d = 400 degrees C, about 200 degrees C lower than that of SrRuO3. The BST (100 nm) deposited on the BRO showed a (110) preferred orientation and crystallization formation at temperatures as low as 200 degrees C. An interfacial layer and the local epitaxial growth of BST on BRO layers within columnar grains were confirmed by high-resolution transmission-electron microscopy studies. Uniform I-V characteristics (I < 1 x 10(-7) A/cm(2)) for bias voltages in the range 0.0-3.0 V of all the BST films deposited within T-d = 300-500 degrees C were observed. The dielectric constants of the BST films (e.g., epsilon(r) = 300 at T-d = 400 degrees C) are considerably higher than those generally achievable for the same T-d by using Pt bottom electrodes. The dependence of the annealing atmosphere (N-2 and O-2) Of the dielectric constants was studied and attributed to a diffused BST/BRO interfacial layer which is semiconductive in a reduced state and insulating in an oxidized state. (C) 1998 American Institute of Physics. [S0003-6951(98)01910-X].
Persistent currents in toroidal carbon nanotubes
(1998-03-15)
Lin, MF
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
The geometric structure of the toroidal carbon nanotubes (TCN's) determines the electronic structure and thus the characteristics of the persistent current. Such current is caused by the magnetic flux phi through TCN's. The semiconducting TCN's exhibit diamagnetism at small phi, which is in great contrast with paramagnetism of the metallic TCN's. The induced magnetic moment is proportional to the toroid radius, but independent of the toroid width. The magnetic response is weak, while it is much stronger than that of a mesoscopic semiconductor or metal ring. The persistent current is a linearly periodical function of phi, with a period phi(0)(hc/e). Such an oscillation is the manifestation of the Aharonov-Bohm (AB) effect. Temperature (T) does not destroy the periodical AB oscillation, although it would significantly reduce the persistent currents. The Zeeman splitting may lead to the destruction of the periodicity at very large phi. A larger TCN at lower T and phi is relatively suitable for verifying the AB effect.
一句詩
(1998-03-15)
管管
一句詩
(1998-03-15)
管管
一句詩
(1998-03-15)
管管
The Doyen-Wilson theorem for maximum packings of K-n with 4-cycles
(1998-03-15)
Fu, HL
;
Lindner, CC
;
應用數學系
;
Department of Applied Mathematics
Necessary and sufficient conditions are given to embed a maximum packing of K-m with 4-cycles into a maximum packing of K-n with 4-cycles, both when the leave of the given packing is preserved, and when the leave of the given packing is not necessarily preserved.
一句詩
(1998-03-15)
管管
Arsenic precipitate accumulation in alternately Si/Be delta-doped GaAs grown by low-temperature molecular beam epitaxy
(1998-03-15)
Hsieh, LZ
;
Huang, JH
;
Su, ZA
;
Wu, MC
;
電子物理學系
The precipitation of arsenic in alternately [Si]=1.0 x 10(13) cm(-2) and [Be]=1.0 x 10(14) cm(-2) delta-doped GaAs grown at low temperature by molecular beam epitaxy has been studied using transmission electron microscopy. Following annealing at 600, 700 and 800 degrees C, As precipitates were found to form preferentially not only on planes of Si but also on planes of Be. The as-grown and annealed samples were also characterized using secondary ion mass spectroscopy, and the results revealed that the interdiffusion of Si and Be dopants due to annealing was discernible. This is the first observation of As precipitate accumulation on Be delta-doped planes in low-temperature grown GaAs.
Observation of self-starting phase-conjugate oscillation in a planar nematic liquid-crystal cell
(1998-03-16)
Chen, SH
;
Shen, YH
;
光電工程學系
;
Department of Photonics
We report the observation of self-starting optical phase-conjugate oscillation in a nematic liquid-crystal cell. A theoretical model based on the continuum theory of liquid crystals and optical theory of degenerate four-wave mixing is developed to explain the observed phenomena. (C) 1998 American Institute of Physics.
An approximately global optimization method for assortment problems
(1998-03-16)
Li, HL
;
Chang, CT
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Assortment problems occur when we want to cut a number of small rectangular pieces from a large rectangle to get the minimum area within the rectangle. Recently, Chen et al. proposed a useful model for assortment problems. Although Chen et al.'s model is quite promising to find solutions, there are two inadequacies in their model: firstly, the objective function in their model is a polynomial term, which may not lead to a globally optimal solution; secondly, too many 0-1 variables are used to formulate the non-overlapping constraints. We propose a new method to reformulate an assortment model. Our model is not only able to find the approximately global optimal solution, but involves less 0-1 variables for formulating non-overlapping constraints. (C) 1998 Elsvier Science B.V.
Liquid crystal display with wide viewing angle
(1998-03-16)
Liang, BJ
;
Chen, SH
;
Wang, YF
;
光電工程學系
;
Department of Photonics
A conic-cylindrical-cavities liquid crystal (conic CCLC) cell is developed for wide-viewing-angle displays. This conic-CCLC cell has been successfully manufactured and inquired. This display has a superwide viewing angle of over +/- 70 degrees in both the horizontal and vertical directions under the condition of no gray-scale inversion. The enhancement of viewing angle is believed to result from the director symmetric alignment in the conic-CCLC. (C) 1995 American Institute of Physics.
Gain flattening of erbium-doped fibre amplifier using fibre Bragg gratings
(1998-03-19)
Dung, JC
;
Chi, S
;
Wen, SF
;
光電工程學系
;
Department of Photonics
A new technique, using fibre-Bragg gratings with different centre frequencies to reflect the different channel signals at different positions, is proposed for flattening the gain spectrum of an erbium-doped fibre amplifier. A designed gain excursion of <0.1dB can be achieved for 16 channel multiplexed signals with 0.1mW input power in the 1532-1562nm wavelength region.
Secure broadcasting in large networks
(1998-03-25)
Sun, HM
;
Shieh, SP
;
資訊工程學系
;
Department of Computer Science
It is common that users or hosts in a large network are partitioned and organized as a hierarchical tree where children of the same parent form a group. Secure broadcasting intends to provide a secure communication channel from a sending principal to a group of legal receiving principals. Only legal receiving principals can decrypt the message, and illegal receiving principals cannot acquire any information from the broadcasted message. In this paper, we propose a secure broadcasting protocol in which only one packet is transmitted for every broadcast, and the size of the broadcasted packet is small. (C) 1998 Elsevier Science B.V.
Bandwidth assignment paradigms for broadband integrated voice/data networks
(1998-03-25)
Yuang, MC
;
Huang, YR
;
資訊工程學系
;
Department of Computer Science
Broadband Integrated Services Digital Networks (BISDNS)/Asynchronous Transfer Mode (ATM) are expected to support diverse applications demanding different bandwidth and Quality of Services (QoSs). Particularly for integrated voice and data networks, voice traffic results in call losses and data traffic suffers from longer delays should networks have insufficient bandwidth. The main goal of the paper is to analytically determine optimal bandwidth allocated to voice and data by means of a queueing model with heterogeneous arrivals and multiple designated channels. The accuracy of analytical results is confirmed by simulation results. On the basis of the analysis, the paper proposes a bandwidth assignment paradigm for the assignment of network bandwidth to voice and data in an effort to guarantee minimal data delay and voice call blocking probability. The run time complexity of the bandwidth assignment computation and paradigm construction is shown to be polynomial bounded. Consequently, the resulting bandwidth assignment assures QoSs in terms of data delay and voice call blocking probability under various network loads. (C) 1998 Elsevier Science B.V.
Dielectric tunability of barium strontium titanate/silicone-rubber composite
(1998-03-30)
Liou, JW
;
Chiou, BS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The dielectric tunability, which is defined as the percentage change of the permittivity under DC biasing, is over 30% for polycrystalline barium strontium titanate (BST) under a field of 5000 V cm(-1) at around the Curie peak. Various volume fractions (18%, 40%, 52%, and 64%) of BST powder are mixed with silicons rubber to obtain a multi-phase dielectric composite. The effective permittivity of the composite follows the Maxwell-Garnett relation with a shape parameter of about 14 for volume fractions below 52%. The dielectric tunabilities at 5000 V cm(-1) for the samples made with 52% and 64% powder are about 0.7% and 7.4%, respectively. The results are compared to the dielectric tunabilities obtained on the basis of series, parallel, and logarithmic models. It is suggested that the dielectric tunability is enhanced when a sample with a more continuous BST powder phase is obtained. An increase of the permittivity with a small DC field applied to the composite is attributed to the effect of polarization of the interface between the BST and silicone-rubber phases.
【海天遊蹤】托雷多行腳
(國立陽明大學牙醫校友會, 1998-04)
葉光儀
交大登山社的點滴
(交大青年社, 1998-04)
山坳
在交大登山社已經三年半了，很高興藉著交青社徵稿的時候，表達自己參與登山社活動的一些感想。
女之秋
(交大青年社, 1998-04)
粟本亞美
深閨怨，千堆愁，有誰知，有誰憐。等待，一復如是的等待，愛與恨已經變得不重要了。