Browsing by Author "Chen, L. C."

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COLLOCATION-AIDED ADJUSTMENT OF HETEROGENEOUS MODELS FOR SATELLITE IMAGES
(2010)
Chang, W. C.
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Chen, L. C.
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Teo, T. A.
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土木工程學系
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Department of Civil Engineering
The geometric correction for satellite images is an important task in remote sensor applications. The geometric correction methods for satellite images include rigorous sensor model (RSM) and rational function model (RFM). RSM describes the relationship between object points and image coordinates through exterior orientation parameters (EOPs). RFM uses the Rational Polynomial Coefficients (RPCs) to transform object coordinates into image space. Thus, treated parameters in the block adjustment for those two models are heterogeneous. In fact, the availability of those parameters is satellite dependent. Thus, the heterogeneous models between RSM and RFM should be combined in the block adjustment when those two types of images are integrated. Considering the global geometry, the block adjustment for all images is to keep the geometrical registration consistent. There might still remain local systematic errors. Thus, this paper proposes a collocation-aided block adjustment for multi-sensor images. The Direct Georeferencing, which is one of RSM, and the RFM are combined a mathematical model for block adjustment. Then the least squares collocation is included to compensate the systematic errors for those heterogeneous models. Besides, to adapt for the weakly convergent geometry, which happens frequently, a digital elevation model is employed as the elevation control in the block adjustment. The test data set includes GeoEye, QuickBird, WorldView-1, Kompsat-2, and Formosat-2 satellite images. The validation includes the checks for absolute accuracy and relative discrepancy among those images. Experimental results indicate that the proposed block adjustment significantly improved both the absolute accuracy and relative discrepancy.
Controlled density growth of carbon nanotubes and its improvement on field emission properties
(2004)
Juan, C. P.
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Tsai, C. C.
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Chen, K. J.
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Hong, W. K.
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Lin, K. C.
The density distribution of the CNTs is one of the crucial parameters for the field emission property of CNTs.We use an inactive thin film layer that was deposited on the catalyst to effectively control the density of the CNTs. The results showed the improved field emission property could be obtained with a thin SiO layer on the catalyst layer as the precursor. For the 3.5 nm Fe and 3.5 nm SiO on 3.5 nm Fe as the catalyst, the turn-on field can be reduced from 3.7 V/ mu m. to 2.2 V/ mu m and the field emission current density increased from 2.6x 10(-8) A/cm(2) to 2.4x 10(-4) A/cm(2) when the applied field was 4 V/mu m. The extremely low turn-on field of 1.3 V/ mu m was also discovered for the CNTs grown with the precursor contained 1.5 nm SiO on 1.5 nm Fe; the extremely high emission current density of 4x 10(-2) A/cm(2) was also achieved under the low electric field of 3.5 V/ mu m.
Crystal symmetry breaking of wurtzite to orthorhombic in nonpolar a-ZnO epi-films
(2009)
Kuo, C. C.
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Liu, W. -R.
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Hsieh, W. F.
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Hsu, C. -H.
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Hsu, H. C.
Crystal symmetry breaking of wurtzite C(6V) to orthorhombic C(2V) due to in-plane anisotropic strain was investigated for nonpolar a-ZnO epi-films grown on R-sapphire.
Crystal symmetry breaking of wurtzite to orthorhombic in nonpolar a-ZnO epifilms
(2009-07-06)
Kuo, C. C.
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Liu, W. -R.
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Hsieh, W. F.
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Hsu, C. -H.
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Hsu, H. C.
Crystal symmetry breaking of wurtzite C-6V to orthorhombic C-2V due to in-plane anisotropic strain was investigated for nonpolar (11 (2) over bar0) ZnO epifilms grown on the R-sapphire. X-ray diffraction results reveal the epilayer is subjected to a compressive strain along the polar c-axis and tensile strains along both a-[11 (2) over bar0] surface normal and in-plane p-[1 (1) over bar 00] axis. The polarized Raman spectra of E-2 modes reveal violation of the C-6V selection rules. Oppositely, the C-2V configuration satisfies the selection rules for the Raman modes. The observed E-1 and E-2 bands in polarized optical reflection and photoluminescence spectra confirm the anisotropic strain causes the structure change to the orthorhombic one. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3159470]
Effects of nitrogen-doping on the microstructure, bonding and electrochemical activity of carbon nanotubes
(2009-02-01)
Lin, Y. G.
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Hsu, Y. K.
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Wu, C. T.
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Chen, S. Y.
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Chen, K. H.
Vertically aligned carbon nanotubes produced with in-situ doping of nitrogen (CN(x) NTs) during chemical vapor deposition exhibit unique structural and electrochemical properties, which are strongly correlated with their nitrogen (N) doping level. In this work, the effects of N-doping on CN(x) NTs have been systematically investigated via microstructure and bonding studies, electron-transfer (ET) behaviors, and subsequent electrochemical deposition of catalyst. The CN(x) NTs doped with an optimal N level, while showing a nearly reversible ET behavior, in fact exhibit uniform and high density of surface defects. These surface defects are desirable for further modification and/or nucleation of catalytic particles on the surface of CN(x) NTs to form a composite electrode for electrochemical energy device applications such as fuel cells and capacitors. (c) 2008 Elsevier B.V. All rights reserved.
Geometrical correlations of quantum dots in InAs/GaAs superlattice structure from electron tomography
(2008-10-13)
Wu, Y. H.
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Chang, L.
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Chen, L. C.
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Chen, H. S.
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Chen, F. R.
In this study, the three-dimensional (3D) information about the structural properties of quantum dots (QDs) in InAs/GaAs superlattice structure has been illustrated using electron tomography in the mode of high-angle angular dark-field scanning transmission electron microscopy. Comparison of this 3D reconstruction with the two-dimensional projection at the same positions is made. The structural properties of embedded quantum dots have been evaluated from electron tomography. The correlation relationship of QDs in superlattice structure has been understood by accurate measurements of 3D geometric positions, which can be free of the overlapping effect from 2D cross section along different crystallographic orientations. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2998693]