Browsing by Issue Date, starting with "1998-08-04"

Now showing 1 - 20 of 81931

On multirate rearrangeable Clos networks
(1998-08-04)
Du, DZ
;
Gao, B
;
Hwang, FK
;
Kim, JH
;
應用數學系
In the multirate switching environment each (connection) request is associated with a bandwidth weight. We consider a three-stage Clos network and assume that each link has a capacity of one (after normalization). The network is rearrangeable if for all possible sets of requests such that each input and output link generates a total weight not exceeding one, there always exists a set of paths, one for each request, such that the sum of weights of all paths going through a link does not exceed the link capacity. The question is to determine the minimum number of center switches which guarantees rearrangeability. We obtain a lower bound of 11n/9 and an upper bound of 41n/16. We then extend the result for the three-stage Clos network to the multistage Clos network. Finally, we propose the weighted version of the edge-coloring problem, which somehow has escaped the literature, associated with our switching network problem.
Multichannel add/drop and cross-connect using fibre Bragg gratings and optical switches
(1998-08-06)
Liaw, SK
;
Ho, KP
;
Chi, S
;
光電工程學系
;
Department of Photonics
A dynamically selective wavelength add/drop multiplexer (WADM) and a multiwavelength cross-connect (M-XC) configuration for dense wavelength division multiplexed networks are proposed. Multiple channels add/drop and/or cross-connect can be realised according to the control of the optical switches and fibre Bragg gratings arrangement. The selective WADM and M-XC devices could provide more reconfigurable flexibility and survivability in WDM networks.
作家生日感言
(1998-08-09)
管管
Excimers in light-emitting conjugated polymers
(1998-08-15)
Meng, HF
;
物理研究所
;
Institute of Physics
The electronic structures of the low-lying excited states for two parallel chains of poly (p-phenylene-vinylene) with arbitrary relative positions are studied. The interchain interaction is treated microscopically. The energy and charge transfer fraction of the (light-emitting) lowest singlet state are found to depend sensitively on the horizontal shift of the two chains, which is in turn determined by the packing geometry. Our predictions of the excimer-forming geometry and the relative (dipole-forbidden) photoluminescence lifetimes are in excellent agreement with experiments.
On the time complexity of minimum and maximum global snapshot problems
(1998-08-17)
Chen, LB
;
Wu, IC
;
資訊工程學系
;
Department of Computer Science
Deriving the minimum and maximum global snapshots is very useful for some error detection problems in distributed programs. Several researchers, e.g., Groselj, Chen and Wu, have shown that the minimum and maximum global snapshot problems are linear-time reducible to the maximum constant-ratio network flow (MCNF) problem, here defined as the well-known maximum network flow problem with m = Theta(n), where m is the number of edges and n is the number of vertices in the given flow network. In this paper we show in a reverse way that the MCNF problem is also linear-time reducible to these global snapshot problems. Thus, we can conclude that the global snapshot problems are "as difficult as" the MCNF problem in terms of time complexity. (C) 1998 Elsevier Science B.V. All rights reserved.
A three-intensity technique for polarizer-sample-analyser photometric ellipsometry and polarimetry
(1998-08-21)
Chao, YF
;
Lee, WC
;
Hung, CS
;
Lin, JJ
;
交大名義發表
This work presents a novel three-intensity-measurement technique to determine the ellipsometric parameters psi and Delta in a polarizer-sample-analyser photometric ellipsometer. This technique can be employed to correct the azimuthal misalignment of the analyser with respect to the plane of incidence. By performing two sets of measurements with this technique with the polarizer's azimuth at +45 degrees and -45 degrees, respectively, we can simultaneously determine the azimuthal deviation of the polarizer and further improve the ellipsometric measurements. Applying this technique in the transmission mode allows us to obtain the phase retardation and the optical axis of a waveplate at the same time.
The photolysis and thermolysis of nitrogen-containing sultines in the preparation of heterocyclic-O-quinodimethanes.
(1998-08-23)
Chung, WS
;
Liu, JH
;
應用化學系
;
Department of Applied Chemistry
Synthetic studies towards laurobtusol.
(1998-08-23)
Ho, TL
;
Yeh, ST
;
應用化學系
;
Department of Applied Chemistry
青藤書屋那根青藤
(1998-08-26)
管管
秋瑾先生的擘窠大書
(1998-08-27)
管管
林耀堂繪筆閱讀詩人
(1998-08-27)
黃寶萍
On metric dependence of Vilkovisky-DeWitt effective potential
(1998-08-30)
Kao, WF
;
Lin, SW
;
電子物理學系
;
物理研究所
;
Department of Electrophysics
It is known that the Vilkovisky-DeWitt effective potential for Einstein gravity depends on the choice of the metric of configuration space. We will show that this metric dependence occurs not only in gauge field theories, but also in scalar fields as well as other field theories with "unnatural" initial choices of metric. This means that the problem of metric dependence relates to initial field parametrization but not gauge symmetry.
三昧書屋的小魯迅
(1998-08-31)
管管
On the stability of the hybrid-damped resolved-acceleration control
(1998-09-01)
Lin, SK
;
Wu, SL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper points out that the stability analysis of the hybrid-damped resolved-acceleration control in our earlier work is incomplete, since the stability was concluded directly from the fact that the joint velocities come to rest as time approaches infinity. A similar incomplete technique was also used in the work of Wampler and Leifer to prove the stability of a damped least-squares resolved-acceleration control scheme. In this paper, we use LaSalle's invariance principle rigorously to show that the solution trajectory of the hybrid-damped resolved-acceleration control will eventually come to the target without steady-state error or will stay at a kinematic singular point with some steady-state error. Discussions on the case of staying at a singular point are also given. (C) 1998 John Wiley & Sons, Inc.
Dilation to the unilateral shifts
(1998-09-01)
Takahashi, K
;
Wu, PY
;
應用數學系
;
Department of Applied Mathematics
The classical result of Foias says that an operator power dilates to a unilateral shift if and only if it is a C-.o contraction. In this paper, we consider the corresponding question of dilating to a unilateral shift. We show tht for contractions with, at least one defect index finite, dilation and power dilation to some unilateral shift amount to the same thing. The only difference is on the minimum multiplicity of the unilateral shift to which the contraction can be (power) dilated. We also obtain a characterization of contractions which are finite-rank perturbations of a unilateral shift, generalizing the rank-one perturbation result of Nakamura.
羅漢床上數羅漢
(1998-09-01)
管管
Diatomic molecule under pulsed field: One-dimensional versus full-dimensional studies
(1998-09-01)
Lin, JT
;
Chuu, DS
;
Jiang, TF
;
電子物理學系
;
物理研究所
This work investigates the dissociation dynamics of a diatomic molecule under the chirped pulse with the vibrational and rotational degrees of freedom. Results obtained herein are also compared with those of the conventionally used one-dimensional (ID) model. According to the comparison, the 1D model still provides valuable information such as dissociation dynamics. Meanwhile, predictions such as harmonic generation spectrum from the 1D model are impractical.
On stationarizability for nonstationary 2-D random fields using discrete wavelet transforms
(1998-09-01)
Wu, BF
;
Su, YL
;
電機資訊學士班
;
Undergraduate Honors Program of Electrical Engineering and Computer Science
The emphasis in this correspondence is on the study of nonstationary two-dimensional (2-D) random fields with wide-sense stationary increments, wide-sense stationary jumps, and 2-D fractional Brownian motion (fBm) fields. The effort made in this work is to develop a realizable method of stationarization provided for nonstationary 2-D random fields. We also present the correlation functions of the discrete wavelet transform relating to 2-D fBm fields that will decay hyperbolically fast.
ZK-type dual-lead worm and worm gear drives: Contact teeth, contact ratios and kinematic errors
(1998-09-01)
Bair, BW
;
Tsay, CB
;
機械工程學系
;
Department of Mechanical Engineering
Contact ratio is an important gear design parameter for gear bending and contact stresses. A higher contact ratio may reduce the stresses and kinematic errors of the gear set. In this study, we calculate the kinematic error of the ZK-type dual-lead worm gear set by applying the tooth contact analysis (TCA) method. Two kinds of contact ratios, the instantaneous contact teeth (ICT) and the average contact ratio (ACR), are investigated and calculated by applying TCA method. ICT is an important design parameter for a dual-lead worm gear set when the gear set is used in a machine subjected to large impact forces. ACR is also a useful design factor for assessing gear tooth strength and dynamic load. If gear surface elastic deformation 3 mu m is allowed for the worm gear set, the ICT may have 2, 3 or 4 teeth and the ACR reveals that the ZK-type dual-lead worm gear drive is a high-contact-ratio gear set. It is found that this type of worm gear set with a shorter center distance assembly can increase the value of ACR during the gear meshing. Illustrative examples presented herein demonstrate the effects of gear parameters on contact teeth, contact ratios, average contact ratios and kinematic errors under various conditions.
Improved output ESD protection by dynamic gate floating design
(1998-09-01)
Chang, HH
;
Ker, MD
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A dynamic gate Boating design is proposed to improve ESD robustness of the CMOS output buffers with small drive capability. By using this novel design, the human-body-model (machine-model) ESD failure threshold of a 2-mA CMOS output buffer has been practically improved from 1 KV (100 V) to greater than 8 KV (1500 V) in a 0.35-mu m CMOS process.