2012
2012
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Record 253 of
Title:Sub-pixel image motion measurement of space camera based on JTC-CDMA
Author(s):Yi, Hongwei(1); Li, Yingcai(1); He, Tianbin(1); Li, Xuyang(1); Zhao, Hui(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 6 DOI: Published: June 2012Abstract:The optical joint transform correlator (JTC) is an effective technical means of image motion measurement of the pushbroom space camera. JTC-CDMA is an improved optical joint transform correlator which can reduce the space-bandwidth product and separate the autocorrelation peak and cross correlation peak effectively, and is helpful to miniaturization. The basic principles of JTC-CDMA were analyzed and the problems in image motion measurement by JTC-CDMA were discussed. Aiming at these problems, a new method was proposed. The feasibility of this method was evaluated and analyzed by computer simulation. The simulation results show that the RMS error of image motion measurement can be controlled below 0.1 pixels in two directions, which could meet the requirement of the space camera.Accession Number: 20123715424658 -
Record 254 of
Title:Vector solitons with polarization instability and locked polarization in a fiber laser
Author(s):Tang, Dingkang(1,2); Zhang, Jian-Guo(1,3); Liu, Yuanshan(1)Source: Optical Engineering Volume: 51 Issue: 7 DOI: 10.1117/1.OE.51.7.074202 Published: July 2012Abstract:We investigate the characteristics of vector solitons with and without locked phase velocities of orthogonal polarization components in a specially-designed laser cavity which is formed by a bidirectional fiber loop together with a semiconductor saturable absorber mirror. The characteristics of the two states are compared in the temporal and spectrum domain, respectively. Both of the two states exhibit the characteristic of mode locking while the two orthogonal polarization components are not resolved. However, for the vector soliton with unlocked phase velocities, identical intensity varies after passing through a polarization beam splitter (PBS) outside the laser cavity. Contrary to the polarization rotation locked vector soliton, the intensity does not change periodically. For the polarization-locked vector soliton (PLVS), the identical pulse intensity is still obtained after passing through the PBS and can be observed on the oscilloscope screen after photodetection. A coupler instead of a circulator is integrated in the laser cavity and strong interaction on the polarization resolved spectra of the PLVS is observed. By comparing the two states, we conclude that interaction between the two orthogonal components contributes to the locked phase velocities. ? 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20140217172181 -
Record 255 of
Title:Synthesis of a soluble polythiophene copolymer with thiophene-vinylene conjugated side chain and its applications in photovoltaic devices
Author(s):Qu, Bo(1); Jiang, Zhongliang(2); Chen, Zhijian(1); Xiao, Lixin(1); Tian, Di(2); Gao, Chao(2,3); Wei, Wei(3,4); Gong, Qihuang(1)Source: Journal of Applied Polymer Science Volume: 124 Issue: 2 DOI: 10.1002/app.35078 Published: April 15, 2012Abstract:A new soluble polythiophene copolymer with thiophene-vinylene conjugated side chain poly[3-(5′-octylthienylenevinyl) thiophene]-thiophene (POTVTh-Th) was successfully synthesized and characterized using NMR, UV-visible spectroscopy, etc. To study the photovoltaic property of the copolymer, photovoltaic device of ITO/PEDOT:PSS/POTVTh-Th:[6,6]-phenyl C 61-butyric acid methyl ester (PC61BM) (weight ratio being 1: 1)/LiF/Al was fabricated, in which POTVTh-Th acted as the electron donor in the active layer. Under 100 mW/cm2 AM 1.5G simulated solar emission, the open-circuit voltage and the short-circuit current density of the device were 0.58 V and 2.50 mA/cm2, respectively. The power conversion efficiency and the fill factor of the photovoltaic device were evaluated to be 0.42% and 0.30. ? 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012.Accession Number: 20120214667873 -
Record 256 of
Title:Matrix completion by Truncated Nuclear Norm Regularization
Author(s):Zhang, Debing(1); Hu, Yao(1); Ye, Jieping(2); Li, Xuelong(3); He, Xiaofei(1)Source: Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition Volume: Issue: DOI: 10.1109/CVPR.2012.6247927 Published: 2012Abstract:Estimating missing values in visual data is a challenging problem in computer vision, which can be considered as a low rank matrix approximation problem. Most of the recent studies use the nuclear norm as a convex relaxation of the rank operator. However, by minimizing the nuclear norm, all the singular values are simultaneously minimized, and thus the rank can not be well approximated in practice. In this paper, we propose a novel matrix completion algorithm based on the Truncated Nuclear Norm Regularization (TNNR) by only minimizing the smallest N-r singular values, where N is the number of singular values and r is the rank of the matrix. In this way, the rank of the matrix can be better approximated than the nuclear norm. We further develop an efficient iterative procedure to solve the optimization problem by using the alternating direction method of multipliers and the accelerated proximal gradient line search method. Experimental results in a wide range of applications demonstrate the effectiveness of our proposed approach. ? 2012 IEEE.Accession Number: 20124015484351 -
Record 257 of
Title:Color fractal structure model for reduced-reference colorful image quality assessment
Author(s):He, Lihuo(1); Wang, Dongxue(1); Li, Xuelong(2); Tao, Dacheng(3); Gao, Xinbo(1); Gao, Fei(1)Source: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) Volume: 7664 LNCS Issue: PART 2 DOI: 10.1007/978-3-642-34481-7_49 Published: 2012Abstract:Developing reduced reference image quality assessment (RR-IQA) plays a vital role in dealing with the prediction of the visual quality of distorted images. However, most of existing methods fail to take color information into consideration, although the color distortion is significant for the increasing color images. To solve the aforementioned problem, this paper proposed a novel IQA method which focuses on the color distortion. In particular, we extract color features based on the model of color fractal structure. Then the color and structure features are mapped into visual quality using the support vector regression. Experimental results on the LIVE II database demonstrate that the proposed method has a good consistency with the human perception especially on images with color distortion. ? 2012 Springer-Verlag.Accession Number: 20124715683155 -
Record 258 of
Title:All-fiber 40GHz femtosecond pulse train source
Author(s):Tang, Dingkang(1,2); Zhang, Jianguo(1,3); Liu, Yuanshan(1)Source: Advanced Materials Research Volume: 529 Issue: DOI: 10.4028/www.scientific.net/AMR.529.169 Published: 2012Abstract:We experimentally demonstrate an all-fiber method to generate a high-quality femtosecond pulse train with a repetition rate of 40GHz. A continuous wavelength laser together with an intensity modulator is used to generate an initial pulse train with a repetition rate of 40GHz. Highly nonlinear fiber (HNLF) together with single mode fiber is utilized to compress the initial pulse from 7.8ps to 985fs. The autocorrelation trace has a good sech 2 profile with no pedestal. This pulse source has a potential to be multiplexed to a higher repetition rate for its narrow pulse width. This method is high-quality, cost-effective and can be easily integrated with the fiber system. ? (2012) Trans Tech Publications, Switzerland.Accession Number: 20124415617002 -
Record 259 of
Title:Real-time three-dimensional object capturing and mapping with optical correlators
Author(s):He, Zhengquan(1); Li, Yulin(1); Huang, Xiangsheng(2); Kong, Depong(1); Zhang, Minrui(1); Guo, Xiaoyi(1)Source: Advanced Materials Research Volume: 586 Issue: DOI: 10.4028/www.scientific.net/AMR.586.374 Published: 2012Abstract:In this paper a new strategy for real-time three-dimensional object capturing and mapping is proposed by using optical correlators. A spatial light modulator is applied in the new strategy. Owing to the properties of quickly parallel processing of optical correlation algorithm the technique can also implement real time object capturing and track, and, as for human body recognition the gesture of body parts can also be portrayed. ? (2012) Trans Tech Publications, Switzerland.Accession Number: 20125015787492 -
Record 260 of
Title:Vector solitons with polarization instability and locked polarization in a fiber laser
Author(s):Tang, Dingkang(1,2); Zhang, Jian-Guo(1,3); Liu, Yuanshan(1)Source: Optical Engineering Volume: 51 Issue: 7 DOI: 10.1117/1.OE.51.7.074202 Published: July 2012Abstract:We investigate the characteristics of vector solitons with and without locked phase velocities of orthogonal polarization components in a specially-designed laser cavity which is formed by a bidirectional fiber loop together with a semiconductor saturable absorber mirror. The characteristics of the two states are compared in the temporal and spectrum domain, respectively. Both of the two states exhibit the characteristic of mode locking while the two orthogonal polarization components are not resolved. However, for the vector soliton with unlocked phase velocities, identical intensity varies after passing through a polarization beam splitter (PBS) outside the laser cavity. Contrary to the polarization rotation locked vector soliton, the intensity does not change periodically. For the polarization- locked vector soliton (PLVS), the identical pulse intensity is still obtained after passing through the PBS and can be observed on the oscilloscope screen after photodetection. A coupler instead of a circulator is integrated in the laser cavity and strong interaction on the polarization resolved spectra of the PLVS is observed. By comparing the two states, we conclude that interaction between the two orthogonal components contributes to the locked phase velocities. ? 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20134216858958 -
Record 261 of
Title:Sparse representation for blind image quality assessment
Author(s):He, Lihuo(1); Tao, Dacheng(2); Li, Xuelong(3); Gao, Xinbo(1)Source: Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition Volume: Issue: DOI: 10.1109/CVPR.2012.6247795 Published: 2012Abstract:Blind image quality assessment (BIQA) is an important yet difficult task in image processing related applications. Existing algorithms for universal BIQA learn a mapping from features of an image to the corresponding subjective quality or divide the image into different distortions before mapping. Although these algorithms are promising, they face the following problems: 1) they require a large number of samples (pairs of distorted image and its subjective quality) to train a robust mapping; 2) they are sensitive to different datasets; and 3) they have to be retrained when new training samples are available. In this paper, we introduce a simple yet effective algorithm based upon the sparse representation of natural scene statistics (NSS) feature. It consists of three key steps: extracting NSS features in the wavelet domain, representing features via sparse coding, and weighting differential mean opinion scores by the sparse coding coefficients to obtain the final visual quality values. Thorough experiments on standard databases show that the proposed algorithm outperforms representative BIQA algorithms and some full-reference metrics. ? 2012 IEEE.Accession Number: 20124015484219 -
Record 262 of
Title:Frequency-selective nanostructured plasmonic absorber by highly lossy interface mode
Author(s):Gong, Y.(1,2); Li, K.(1,2); Huang, J.(2); Copner, N.J.(2); Davies, A.(3); Wang, L.(1); Duan, T.(1)Source: Progress in Electromagnetics Research Volume: 124 Issue: DOI: 10.2528/PIER11121903 Published: 2012Abstract:We report on an existence of a highly lossy interface mode (HLIM) in a designed plasmonic nanostructure for perfect absorption of the incident optical waves. Interactions between the single thin- metallic-layer (TML) and slits arrays for excitation of the HLIM in the proposed plasmonic absorber are investigated, and eigenfrequency formula for the HLIM is derived. Analytical and numerical results show that the HLIM is frequency-selective, opens a narrow and steep absorption band in photonic stopband of the slits arrays. Due to the HLIM lossy characteristic, surface plasmon polaritons are significantly trapped at the TML interface with absorption close to 100%.Accession Number: 20121014833788 -
Record 263 of
Title:Joint learning for single-image super-resolution via a coupled constraint
Author(s):Gao, Xinbo(1); Zhang, Kaibing(1); Tao, Dacheng(2); Li, Xuelong(3)Source: IEEE Transactions on Image Processing Volume: 21 Issue: 2 DOI: 10.1109/TIP.2011.2161482 Published: February 2012Abstract:The neighbor-embedding (NE) algorithm for single-image super-resolution (SR) reconstruction assumes that the feature spaces of low-resolution (LR) and high-resolution (HR) patches are locally isometric. However, this is not true for SR because of one-to-many mappings between LR and HR patches. To overcome or at least to reduce the problem for NE-based SR reconstruction, we apply a joint learning technique to train two projection matrices simultaneously and to map the original LR and HR feature spaces onto a unified feature subspace. Subsequently, the k-nearest neighbor selection of the input LR image patches is conducted in the unified feature subspace to estimate the reconstruction weights. To handle a large number of samples, joint learning locally exploits a coupled constraint by linking the LR-HR counterparts together with the K-nearest grouping patch pairs. In order to refine further the initial SR estimate, we impose a global reconstruction constraint on the SR outcome based on the maximum a posteriori framework. Preliminary experiments suggest that the proposed algorithm outperforms NE-related baselines. ? 2011 IEEE.Accession Number: 20120514729691 -
Record 264 of
Title:Image super-resolution with sparse neighbor embedding
Author(s):Gao, Xinbo(1); Zhang, Kaibing(1); Tao, Dacheng(2); Li, Xuelong(3,4)Source: IEEE Transactions on Image Processing Volume: 21 Issue: 7 DOI: 10.1109/TIP.2012.2190080 Published: July 2012Abstract:Until now, neighbor-embedding-based (NE) algorithms for super-resolution (SR) have carried out two independent processes to synthesize high-resolution (HR) image patches. In the first process, neighbor search is performed using the Euclidean distance metric, and in the second process, the optimal weights are determined by solving a constrained least squares problem. However, the separate processes are not optimal. In this paper, we propose a sparse neighbor selection scheme for SR reconstruction. We first predetermine a larger number of neighbors as potential candidates and develop an extended Robust-SL0 algorithm to simultaneously find the neighbors and to solve the reconstruction weights. Recognizing that the k-nearest neighbor (k-NN) for reconstruction should have similar local geometric structures based on clustering, we employ a local statistical feature, namely histograms of oriented gradients (HoG) of low-resolution (LR) image patches, to perform such clustering. By conveying local structural information of HoG in the synthesis stage, the k-NN of each LR input patch is adaptively chosen from their associated subset, which significantly improves the speed of synthesizing the HR image while preserving the quality of reconstruction. Experimental results suggest that the proposed method can achieve competitive SR quality compared with other state-of-the-art baselines. ? 2012 IEEE.Accession Number: 20122615154413