2012
2012
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Record 109 of
Title:Robust lossless data hiding using clustering and statistical quantity histogram
Author(s):An, Lingling(1); Gao, Xinbo(1,2); Yuan, Yuan(3); Tao, Dacheng(4)Source: Neurocomputing Volume: 77 Issue: 1 DOI: 10.1016/j.neucom.2011.06.012 Published: 01 February 2012Abstract:Lossless data hiding methods usually fail to recover the hidden messages completely when the watermarked images are attacked. Therefore, the robust lossless data hiding (RLDH), or the robust reversible watermarking technique, is urgently needed to effectively improve the recovery performance. To date a couple of methods have been developed; however, they have such drawbacks as poor visual quality and low capacity. To solve this problem, we develop a novel statistical quantity histogram shifting and clustering-based RLDH method or SQH-SC for short. The benefits of SQH-SC in comparison with existing typical methods include: (1) strong robustness against lossy compression and random noise due to the usage of k-means clustering; (2) good imperceptibility and reasonable performance tradeoff due to the consideration of the just noticeable distortion of images; (3) high capacity due to the flexible adjustment of the threshold; and (4) wide adaptability and good stability to different kinds of images. Extensive experimental studies based on natural images, medical images, and synthetic aperture radar (SAR) images demonstrate the effectiveness of the proposed SQH-SC. ? 2011.Accession Number: 20114614520924 -
Record 110 of
Title:Defect modes supported by optical lattices in photovoltaic-photorefractive crystals
Author(s):Li, Kehao(1,2); Lu, Keqing(1); Guo, Jianbang(1,2); Chen, Weijun(3); Sun, Tongtong(3); Yao, Fengxue(3); Xu, Jingjun(4)Source: Optics Communications Volume: 285 Issue: 13-14 DOI: 10.1016/j.optcom.2012.03.003 Published: June 15, 2012Abstract:We study defect modes in optically induced one-dimensional lattices in photovoltaic-photorefractive crystals. These defect modes exist in different bandgaps due to the change of defect intensity. For a positive defect, defect mode branches exist not only in the semi-infinite bandgap, but also in the first and second bandgaps. When the defect mode branch is fixed, the confinement of defect modes increases with the defect strength parameter. For a negative defect, defect mode branches exist only in the first and second bandgaps. For a given defect mode branch, the strongest confinement of the defect modes appears when the lattice intensity at the defect site is not the smallest in its branch. On the other hand, when the defect strength parameter is fixed, the most localized defect modes arise in the semi-infinite bandgap for the positive defect and in the first bandgap for the negative defect. ? 2012 Elsevier B.V. All rights reserved.Accession Number: 20121614954753 -
Record 111 of
Title:Proton-implanted optical planar waveguides in Yb3+-doped silicate glasses
Author(s):Liu, Chun-Xiao(1,2); Cheng, Shu(3); Guo, Hai-Tao(2); Li, Wei-Nan(2); Liu, Xiu-Hong(4); Wei, Wei(2); Peng, Bo(2)Source: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms Volume: 289 Issue: DOI: 10.1016/j.nimb.2012.08.004 Published: October 15, 2012Abstract:We report on the characterization of planar waveguides in Yb 3+-doped silicate glasses fabricated by double-energy proton implantation at a total dose of 3 × 1016 ions/cm2. The dark mode spectroscopy and near-field mode profile were evaluated by the prism coupling and end-face coupling methods, respectively. The results indicate that a refractive index enhanced region as well as an optical barrier has been created after the beam process. We propose the ion exchange mechanism between the proton and Na+ ions to illustrate the optical barrier and discuss its influence. ? 2012 Elsevier B.V. All rights reserved.Accession Number: 20124115553563 -
Record 112 of
Title:Unclassical ripple patterns in single-crystal silicon produced by femtosecond laser irradiation
Author(s):Zhang, Wei(1,2); Cheng, Guanghua(2); Feng, Qiang(1,3)Source: Applied Surface Science Volume: 263 Issue: DOI: 10.1016/j.apsusc.2012.09.075 Published: December 15, 2012Abstract:Laser-induced periodic surface structures (LIPSS) in single-crystal silicon upon irradiation with multiple linearly polarized femtosecond (fs) laser pulses (120 fs, 800 nm, 1 kHz) were investigated under different laser fluence and pulse number. Unclassical ripples (U-ripples), which were nearly parallel to the polarization of the laser beam, were observed to form gradually on the top of classical ripples with the effective pulse number. Their periods were significantly longer than the laser wavelength, and increased with increasing both the laser fluence and pulse number in the current study. The relationship between the types of ripple patterns and their parametric dependence was established. The mechanism of U-ripple formation was attributed to the capillary wave, arising from the inhomogeneous temperature gradient combined with the electric field of the pulses in the molten surface layer. ? 2012 Elsevier B.V.Accession Number: 20124815712436 -
Record 113 of
Title:Application of MTF in frame design for optical camera
Author(s):Wu, Mengyuan(1); Li, Yingcai(1); Hu, Yongming(1); Yi, Hongwei(1); Han, Juan(1)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 39 Issue: 8 DOI: 10.3788/CJL201239.0816001 Published: August 2012Abstract:In order to direct the truss design of remote sensing camera, the influence of various modulation transfer function (MTF) on camera system is analyzed to satisfy the requirement of system MTF, thus the main support structure is designed by the limit of optical diffraction MTF. The minimum optical diffraction MTF under the situation of truss structure is calculated from the actual MTF, assembly and electronic factor of on-orbit production. Then the MTF is analyzed only by employing the pupil function under various kinds of obstruction because the optical software cannot evaluate the optical diffraction MTF entirely. It is concluded that the max diameter of tri-truss is 38 mm, the max diameter of four-truss is 26 mm. The truss structure of 26 mm diameter and 4 mm thickness is satisfied the specifications of satellite design by analyzing the static deformation and modal frequency of various wall thickness through finite element analysis (FEA).Accession Number: 20124115547695 -
Record 114 of
Title:Content-adaptive reliable robust lossless data embedding
Author(s):An, Lingling(1); Gao, Xinbo(1,2); Yuan, Yuan(3); Tao, Dacheng(4); Deng, Cheng(1); Ji, Feng(1)Source: Neurocomputing Volume: 79 Issue: DOI: 10.1016/j.neucom.2011.08.019 Published: 01 March 2012Abstract:It is well known that robust lossless data embedding (RLDE) methods can be used to protect copyright of digital images when the intactness of host images is highly demanded and the unintentional attacks may be encountered in data communication. However, the existing RLDE methods cannot be applied satisfactorily to the practical scenarios due to different drawbacks, e.g., serious "salt-and-pepper" noise, low capacity and unreliable reversibility. In this paper, we propose an effective solution to RLDE by improving the histogram rotation (HR)-based embedding model. The proposed method is a content-adaptive reliable RLDE or CAR for short. It eliminates the "salt-and-pepper" noise in HR by the pixel adjustment mechanism. Therefore, reliable regions for embedding can be well constructed. Furthermore, we basically expect the watermark strengths to be adaptive to different image contents, and thus we have a chance to make an effective tradeoff between invisibility and robustness. The luminance masking together with the threshold strategy is duly adopted in the proposed RLDE method, so the just noticeable distortion thresholds of different local regions can be well utilized to control the watermark strengths. Experimental evidence on 300 test images including natural, medical and synthetic aperture radar (SAR) images demonstrates the effectiveness of the proposed data embedding method. ? 2011 Elsevier B.V.Accession Number: 20115114630163 -
Record 115 of
Title:Single-shot parallel four-step phase shifting using on-axis Fizeau interferometry
Author(s):Abdelsalam, D.G.(1,2,3); Yao, Baoli(1); Gao, Peng(1); Min, Junwei(1); Guo, Rongli(1)Source: Applied Optics Volume: 51 Issue: 20 DOI: 10.1364/AO.51.004891 Published: July 10, 2012Abstract:The purposes of the paper are threefold: (1) to show the possibility to perform parallel phase-shifting Fizeau interferometry by using a quarter waveplate with high flatness as a reference, (2) to present a comparative study between the phase-shifting algorithm and the off-axis geometry in surface microtopography measurement, and (3) to show the advantages of using the proposed common path Fizeau interferometry over the quasi-common path Michelson interferometry in terms of accuracy in measurement. The compelling advantage of the proposed parallel phase-shifting Fizeau interferometric technique is the long-term stability that leads to measuring objects with a high degree of accuracy. ? 2012 Optical Society of America.Accession Number: 20122915258664 -
Record 116 of
Title:Design of visible light switch-zoom lens of long effective focal length based on Newton system
Author(s):Li, Gang(1); Zhang, Hengjin(1); Jiang, Kai(1); Yang, Xiaoxu(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 32 Issue: SUPPL.1 DOI: 10.3788/AOS201232.s122004 Published: December 2012Abstract:An example is given to explain the design of swith-zoom lens of the long effective focal length working in visible light waveband based on the Newton system. The derivation of the components' focal power and the calculation of the initial parameters are made. Two times imaging structure is adopted and field lens is used to match the pupil for the sake of making up the focal plane's changes because of object distance's differention. Focusing lens is applied and zoom is realized by switching in or out short effective focal length lens between long effective focal length lens and the detector's focal plane. In order to adjust coplane, a parallel path is set in the short effective focal length lens. The design of optimized aberration is made. The analysis of results at various fields is presented. Within 0.8 field of view, modulation transfer function (MTF) is greater than 0.4. From the results, the conclusion can be drawn that the project is rational and the imaging quality is good.Accession Number: 20131016087854 -
Record 117 of
Title:Initialization independent clustering with actively self-training method
Author(s):Nie, Feiping(1); Xu, Dong(2); Li, Xuelong(3)Source: IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics Volume: 42 Issue: 1 DOI: 10.1109/TSMCB.2011.2161607 Published: February 2012Abstract:The results of traditional clustering methods are usually unreliable as there is not any guidance from the data labels, while the class labels can be predicted more reliable by the semisupervised learning if the labels of partial data are given. In this paper, we propose an actively self-training clustering method, in which the samples are actively selected as training set to minimize an estimated Bayes error, and then explore semisupervised learning to perform clustering. Traditional graph-based semisupervised learning methods are not convenient to estimate the Bayes error; we develop a specific regularization framework on graph to perform semisupervised learning, in which the Bayes error can be effectively estimated. In addition, the proposed clustering algorithm can be readily applied in a semisupervised setting with partial class labels. Experimental results on toy data and real-world data sets demonstrate the effectiveness of the proposed clustering method on the unsupervised and the semisupervised setting. It is worthy noting that the proposed clustering method is free of initialization, while traditional clustering methods are usually dependent on initialization. ? 2011 IEEE.Accession Number: 20120514729751 -
Record 118 of
Title:A slot micro/nano fiber with elliptical low-index core
Author(s):Zhang, Wenfu(1); Mu, Jian-Wei(2); Huang, Wei-Ping(3); Zhao, Wei(1)Source: IEEE Photonics Journal Volume: 4 Issue: 5 DOI: 10.1109/JPHOT.2012.2212241 Published: 2012Abstract:A slot micro/nano optical fiber with elliptical low-index core, referred to as the elliptical-slot micro/nano fiber (ESMNF), is studied systematically in great detail in this paper. It is demonstrated that the ESMNF can confine most of the light in the low-index region and hence lead to large field enhancement. Benefiting from the large low-index power confinement factor and the field enhancement, the ESMNF also yields significant nonlinearity enhancement by the proper selection of materials. In addition, large birefringence between the two fundamental polarized modes is observed, due to the breakage of the circular symmetry for the core. The nonlinearity and low-index confinement properties of a more practical elliptical-slot embedded suspended microstructure fiber are also studied. ? 2012 IEEE.Accession Number: 20123615390752 -
Record 119 of
Title:Amplitude weighting method for beamforming in far-field from uniform array
Author(s):Zhong, Lanxian(1,2); Zhang, Zhiyong(1,2)Source: Lecture Notes in Electrical Engineering Volume: 127 LNEE Issue: VOL. 4 DOI: 10.1007/978-3-642-25769-8-11 Published: 2012Abstract:An amplitude weighting method of forming a specific radiation pattern in far-field was proposed, which is different from the phase-array beamforming. The formula for calculating radiation amplitudes was derived in detail. Numerical results illustrated that radiation pattern with limited distribution can be closed in upon by increasing the number of elements, and it was indicated that the total number of elements can be determined in ratio of the main lobe energy to total radiation energy. ? Springer-Verlag Berlin Heidelberg 2012.Accession Number: 20123815452472 -
Record 120 of
Title:Optical planar waveguides in Yb3+-doped phosphate glasses produced by He+ ion implantation
Author(s):Liu, Chun-Xiao(1,2); Li, Wei-Nan(1); Wei, Wei(1,3); Peng, Bo(1,3)Source: Chinese Physics B Volume: 21 Issue: 7 DOI: 10.1088/1674-1056/21/7/074211 Published: July 2012Abstract:Optical planar waveguides in Yb3+-doped phosphate glasses are fabricated by implanting triple-energy helium ions. The guiding modes and the near-field intensity distribution are measured by using the prism-coupling method and the end-face coupling setup with a He - Ne laser at 633 nm The intensity calculation method (ICM) is used to reconstruct the refractive index profile of the waveguide. The absorption and the fluorescence investigations reveal that the glass bulk features are well preserved in the active volumes of the waveguides, suggesting the fabricated structures for possible applications as waveguide lasers. ? 2012 Chinese Physical Society and IOP Publishing Ltd.Accession Number: 20123115293167