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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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Now showing 1 - 10 of 39

Inhomogeneous cellular automata modeling for mixed traffic with cars and motorcycles
(2005-09-01)
Lan, LW
;
Chang, CW
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
This paper develops inhomogeneous cellular automata models to elucidate the interacting movements of cars and motorcycles in mixed traffic contexts. The car and motorcycle are represented by non-identical particle sizes that respectively occupy 6x2 and 2x1 cell units, each of which is 1.25x1.25 meters. Based on the field survey, we establish deterministic cellular automata (CA) rules to govern the particle movements in a two-dimensional space. The instantaneous positions and speeds for all particles are updated in parallel per second accordingly. The deterministic CA models have been validated by another set of field observed data. To account for the deviations of particles' maximum speeds, we further modify the models with stochastic CA rules. The relationships between flow, cell occupancy (a proxy of density) and speed under different traffic mixtures and road (lane) widths are then elaborated.
A video information system for sport motion analysis
(1997-06-01)
Chang, CW
;
Lee, SY
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
In this paper, we present several important methods in a video information system for sport motion analysis. We first describe an efficient method for computing the position of one or more moving objects in a video sequence. We utilize computer vision routines for both target object tracking and feature value extraction. Then, we propose a multiple subsequence matching mechanism for comparing the difference in object motion between two video sequences. A mapping function, penalty table and the overall distance between two video sequences have been defined. We use the prominent feature points as our segmentation positions and separate the sequence into several subsequence groups. After an alignment process, we can find the mapping of the best matching and get an evaluation report between the two video sequences for motion analysis. The video information system described in this paper has successfully analysed several examples of sport motion, and is representative of techniques commonly used in practice. (C) 1997 Academic Press Limited.
Automatic cel painting in computer-assisted cartoon production using similarity recognition
(1997-07-01)
Chang, CW
;
Lee, SY
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
The task of painting each eel of an animated sequence has always been a tedious work using traditional methods. In order to simplify and speed up the process, the development of an automatic eel painting system is desired. This paper presents a method for assisting the production of cartoon animation using computers in order to reduce the production expense and to improve the overall quality. It signals a great improvement in the working environment where 2-D animation Is produced. The basic idea of our automatic eel painting mechanism is to extract both statistical and topological features of regions from input animation drawings, and to search for similar corresponding regions in the previous drawing, If the similarity measures are within the accepted thresholds, the corresponding colour will be inherited. A new integrated labelling algorithm constructing statistical region and topological graph features is proposed. Furthermore, a similarity measure of regions is defined and an algorithm of partial matching of attribute graphs is presented. The experimental result shows the feasibility and practicability of the proposed approach. (C) 1997 by John Wiley & Sons, Ltd.
Determination of dynamic elastic constants of transversely isotropic rocks using a single cylindrical specimen
(1997-10-01)
Liao, JJ
;
Hu, TB
;
Chang, CW
;
土木工程學系
;
Department of Civil Engineering
A new experimental procedure and its associated interpretation theories are proposed to determine the five dynamic elastic constants of a transversely isotropic rock. Using Christoffel's equations, the elastic constants can be uniquely determined based on ultrasonic wave velocity measurements on a single cylindrical specimen. The new method requires that the orientation of planes of elastic symmetry by parallel to its longitudinal axis. The wave velocity measuring devices (i.e. transducers) can be mounted on the sides or ends of the specimen. The new method has been implemented in the laboratory on a transversely isotropic rock, argillite. Wave velocity measurements were taken on specimens with and without a tensile load applied at the ends. Consistent results were obtained in both cases. This paper describes details of the analytical background and the proposed experimental procedure. Available test results are presented to demonstrate the efficacy of the new method. (C) 1997 Elsevier Science Ltd.
Ultrashort pulse generation from mode-locked erbium-doped fibre ring lasers
(1999-07-20)
Chang, CW
;
Chi, S
;
光電工程學系
;
Department of Photonics
A theoretical model of a passively mode-locked erbium-doped fibre ring laser using nonlinear polarization rotation is developed. Numerical simulations are used to study mode-locking and pulse dynamics in a typical ring configuration. The simulations show that stable operation can exist in both isotropic and birefringent fibres, and stable pulses with a FWHM as short as 45 fs can be generated. It is found that there is an optimal regime of ellipticity such that the stable mode-locking can be obtained. In addition, the condition for high birefringence approximation is also found.
Femtosecond fluorescence dynamics of trans-azobenzene in hexane on excitation to the S-1(n,pi*) state
(2002-10-01)
Lu, YC
;
Chang, CW
;
Diau, EWG
;
應用化學系
;
Department of Applied Chemistry
Femtosecond fluorescence dynamics of trans-azobenzene in hexane have been investigated on excitation to the S-1(n,pi*) state at 432 nm using the up-conversion technique. Two transient components were observed to represent the fast and the slow S-1 fluorescence dynamics in the wavelength range of 550-732 nm. Based on the results obtained from recent ab initio calculations (Ishikawa, T.; Noro, T.; Shoda, T., J. Chem. Phys. 2001, 115, 7503), a dynamical picture is given in the following. Upon initial excitation to the S, state, the excited molecule is moving away from the first detection window within the observed 200-300 fs. The structural relaxation from the Franck-Condon region may be responsible for the observed fast S-1 dynamics with the driving force being the CNNC twisting motion along the rotational coordinate. For the rest of the motion on the S-1 global potential surface, the excited molecule may search for the S-0/S-1 conical intersection for an efficient internal conversion to the ground state. The nuclear motions for the observed slow S-1 dynamics not only involve the CNNC torsional coordinate but also the other degrees of freedom such as the CNN bending coordinate on the multidimensional S-1 potential energy surface. The whole electronic relaxation process occurs within the observed 1-2 ps. The slow S-1 dynamics were found to vary with the fluorescence wavelengths due to the influence of the solvent-induced vibrational relaxation in the S-1 state; the vibrational relaxation should occur on a time scale comparable to the time scale of the electronic relaxation (S-1-->S-0 internal conversion).
Fluorescence lifetime and nonradiative relaxation dynamics of DCM in nonpolar solvent
(2003-06-04)
Chang, CW
;
Kao, YT
;
Diau, EWG
;
應用化學系
;
應用化學系分子科學碩博班
The nonradiative dynamics of DCM in hexane have been investigated using femtosecond fluorescence up conversion technique at three excitation wavelengths (400, 445 and 480 nm). The S, lifetime was observed to be 9.8 +/- 0.5 ps, which is independent of the excitation and the fluorescence wavelengths. The observed S, lifetimes of DCJT and DCJTB are slower than those of DCM and DCMB by one order of magnitude, indicating the significance of the twisting motion of the amino group affecting the S, nonradiative dynamics. TDDFT calculations suggest that an intersystem crossing is responsible for the observed S, dynamics of DCM in nonpolar solvent. (C) 2003 Elsevier Science B.V. All rights reserved.
Design of low-loss tapered waveguides using the telescope structure compensation
(2003-10-01)
Chang, CW
;
Wu, ML
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
A low-loss tapered waveguide is achieved by the telescope structure compensation. The configuration of this design is similar to the Galilean telescope based on the bulk geometrical optics. We numerically calculate the transmission efficiency in the use of the beam propagation method (BPM) and the finite-difference time-domain method. The BPM simulation results reveal that the normalized transmission efficiency is more than 95%, even if the tapered angle is as large as 10degrees.
Optical studies of the Holmium-doped InGaAsP epilayers
(2003-12-01)
Lee, YC
;
Shu, GW
;
Cheng, IM
;
Chen, CP
;
Shen, JL
Photoluminescence (PL), contactless electroreflectance (CER), and Raman scattering measurements have been used to study the structural properties of Ho-doped InGaAsP epilayers. Both the full width at half maximum (FWHM) of PL and the broadening parameter of CER are decreased as the doping amount of Ho element increases. This indicates that Ho doping greatly reduces the residual impurities and improve the quality of epilayers. The Raman spectra of Ho-doped InGaAsP epilayers are found to have asymmetric line shapes. Using a spatial correlation model, it is found the asymmetric broadening of the Raman signal is not influenced by the Ho doping. We hence conclude that the introduction of the Ho element can greatly reduce the residual impurities of LPE-grown layers, but no large amounts of Ho element are being incorporated into the epilayers during the purification. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Resolution of the inversion-rotation controversy of azobenzene in solution via femtosecond fluorescence anisotropy on S1 excitation.
(2004-08-22)
Diau, EWG
;
Chang, CW
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry

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