學術出版;;Publications

Permanent URI for this communityhdl:11536/1

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.

Browse

🏛️國立陽明交通大學機構典藏

Search Results

Now showing 1 - 10 of 27

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.
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.
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.
Design and analyses of compact bent-tapered waveguides using guided-wave lens sets
(2004-08-20)
Chang, CW
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
We propose compact bent-tapered waveguides using guided-wave lens sets, which are constructed by disposing lens-shaped waveguide regions in planar tapered waveguides. Two applications of the abruptly bent tapered waveguide and the Z-bend tapered waveguide demonstrate high transmittances of 91% and 86% with bent and tapered angles of 10degrees. (C) 2004 Wiley Periodicals, Inc.
Photoisomerization dynamics of azobenzene in solution with S-1 excitation: A femtosecond fluorescence anisotropy study
(2004-08-18)
Chang, CW
;
Lu, YC
;
Wang, TT
;
Diau, EWG
;
應用化學系
Measurements of anisotropy of femtosecond fluorescence after direct excitation of the S-1(npi(*)) state of azobenzene in hexane and ethylene glycol solutions have been carried out to address the controversy about inversion and rotation in the mechanism of photoisomerization. The observed anisotropies in hexane decay to a nonzero asymptotic level with a relaxation period the same as that for slow decay of the corresponding biexponential transient; this effect is attributed to involvement of the out-of-plane CNNC-torsional motion on approach to a twisted conical intersection along the "rotation channel" that depolarizes the original in-plane transition moment. In contrast, when the rotational channel becomes substantially hindered in ethylene glycol, the anisotropies show no discernible decay feature, but the corresponding transients show prominent decays attributed to involvement of in-plane symmetric motions; the latter approach a planar-sloped conical intersection along a "concerted inversion channel" for efficient internal conversion through vibronic coupling. The proposed mechanism is consistent with theoretical calculations and rationalizes both results on quantum yields and ultrafast observations.
Guided-wave microlens array applications to compact 1x8 planar waveguide splitters
(2004-10-05)
Chang, CW
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
A compact 1 x 8 waveguide splitter using a guided-wave microlens array is presented and analyzed to show low insertion loss and output imbalance of 0.28 and 0.15 dB, respectively. The analysis results show that the proposed equal-power splitter with insensitive wavelength responses and acceptable fabrication tolerances is applicable for compact and wide-bandwidth integrated optical devices. (C) 2004 Wiley Periodicals, Inc.
High-efficiency coupling between external and photonic crystal waveguides by longitudinally shifting waveguide junctions
(2004-12-08)
Chang, CW
;
Cheng, SC
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
Longitudinally shifting waveguide junctions can achieve high efficiency light coupling from external silica waveguides into photonic crystal waveguides (PCWs) without requiring taper PCW structures in the waveguide junctions. Due to the periodic field distribution of PCWs along the propagation direction, maximum and minimum coupling efficiency occur when waveguide junctions are located near the peak and valley of the longitudinal mode profile, and coupling efficiency depends on both the localization of mode fields in PCWs and the group velocities of eigenmodes. Coupling efficiency of 86% between silicon/silica PCWs and external silica waveguides can be achieved without the need for special design in the junction region for the reduced-rod PCW. Due to large Bragg reflection, coupling of the band edge modes at the flat dispersion regions that possess small group velocities is inefficient. (C) 2004 Elsevier B.V. All rights reserved.
Improved near-infrared luminescence of si-rich SiO2 with buried Si nanocrystals grown by PECVD at optimized N2O fluence
(2005)
Chen, CY
;
Lin, CJ
;
Kuo, HC
;
Lin, GR
;
Chueh, YL
The optimized N2O fluence for plasma enhanced chemical vapor deposition (PECVD) growing silicon-rich substoichiometric silicon oxide (SiOx) with buried Si nanocrystals is demonstrated. Strong room-temperature photoluminescence (PL) at 550-870 nm has been observed in SiOx thin films grown by PECVD with N2O fluence varying from 105 to 130 sccm. After annealing from 15 to 180 min, a 22-nm-redshift of the PL has been detected. The maximum PL intensity is observed for the 30-min annealed SiOx growing at N2O fluence at 120 sccm. Larger N2O fluence and longer annealing time causes a PL blueshift by 65 nm and 20 nm, respectively. Such a blueshift is attributed to shrinkage in the size of the Si nanocrystals under the participation of dissolved oxygen atoms from N2O. The (220)-oriented Si nanocrystals with radius ranging from 4.4 to 5.0 nm are determined. The luminescent lifetimes lengthens from 20 mu s to 52 mu s as the nc-Si size extends from 4.0 to 4.2 run. Optimal annealing times for SiOx preparing at different N2O fluences and an optimum N2O fluence of 120 sccm are reported. Serious oxidation effect at larger N2O fluence condition is observed, providing smaller PL intensity at shorter wavelengths. In contrast, the larger size nc-Si will be precipitated when N2O fluence becomes smaller, leading to a weaker PL at longer wavelength. These results provide the optimized growth condition for the Si-rich SiO2 with buried Si nanocrystals.

學術出版;;Publications

Browse

Filters

Settings

Sort By

Results per page

🏛️國立陽明交通大學機構典藏

Search Results