2012
2012
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Record 37 of
Title:Focusing properties of the visible light wave through plasmonic lenses with subwavelength chirped slits
Author(s):Feng, Di(1,2); Zhang, Chunxi(2); Yang, Yuanhong(2)Source: Advanced Materials Research Volume: 586 Issue: DOI: 10.4028/www.scientific.net/AMR.586.356 Published: 2012Abstract:Focusing properties of a new kind of plasmonic lenses are investigated in the visible wavelength range through a subwavelength metallic chirped slit arrays which have the same depth but chirped widths. The chirped widths of slits are like a piece-wise-linear distribution which will be approximated by linearly increasing the width of a subwavelength feature and can build up a required phase front for focusing. We analyzed the focusing characteristics of different metallic lenses (silver and gold, respectively) with chirped widths that are obtained by generalizing the relevant phase delay for TE- and TM-polarized incident waves, for different f-numbers of lenses and for different material thickness, respectively. Meanwhile, the comparison of the metallic and dielectric lenses is also presented. The results of calculations show that, the metallic lenses are more sensitive to the polarization of incidence wave than that of dielectric lenses, and can get narrower full-width half-maximum (FWHM) beam width than that of dielectric lenses for TM-polarized incident waves, respectively. No matter which f-number we choose, the FWHM of dielectric lenses are higher than the plasmonic lenses, and the plasmonic lenses can get a higher focal resolution than dielectric lenses do. This kind of plasmonic lenses should have a good potential for applications in photonic and plasmonic integrated devices, sensing, and nano-optical manipulations, etc. ? (2012) Trans Tech Publications, Switzerland.Accession Number: 20125015787489 -
Record 38 of
Title:Coupled directional level set for MR image segmentation
Author(s):Qin, Xianjing(1); Liu, Yang(2); Lu, Hongbing(2); Li, Xuelong(1); Yan, Pingkun(1)Source: Proceedings - 2012 11th International Conference on Machine Learning and Applications, ICMLA 2012 Volume: 1 Issue: DOI: 10.1109/ICMLA.2012.39 Published: 2012Abstract:Segmenting bladder wall for thickness measuring is a fundamental operation in bladder magnetic resonance (MR) image analysis since thickening of the bladder wall may indicate abnormality. Active contours have been used for bladder wall segmentation, which can be broadly divided into gradient-based and region-based methods, according to the used image features. However, the artifacts in MR images and the complex background outside the bladder lead to significant challenges for segmentation. In this paper, a coupled directional level set model is proposed to segment the outer and inner boundaries simultaneously by exploiting the directional gradient, region information and thickness prior of the bladder wall. With our proposed method, the influence of the artifacts in the bladder lumen and the complicated intensity distribution of soft tissues surrounding the bladder can be appreciably reduced. Promising results on 119 bladder MR images have demonstrated the performance of the presented method. ? 2012 IEEE.Accession Number: 20130716027498 -
Record 39 of
Title:Can fixed time delay signature be concealed in chaotic semiconductor laser with optical feedback?
Author(s):Wu, Yuan(1,2,3); Wang, Yun-Cai(1,2,3); Li, Pu(1,2,3); Wang, An-Bang(1,2,3); Zhang, Ming-Jiang(1,2,3)Source: IEEE Journal of Quantum Electronics Volume: 48 Issue: 11 DOI: 10.1109/JQE.2012.2212001 Published: 2012Abstract:External-cavity lasers are usually used for chaos encryption in optical chaos-based communication systems. The external-cavity round-trip time (the time delay in the laser dynamics) is often regarded as an additional key to encode messages, which is a critical security parameter. The feasibility of identifying the time delay has been a crucial issue in chaotic optical communication. Some researchers propose that the time delay can be hidden by modulating the value of feedback strength or increasing the number of feedback cavities. In this paper, we experimentally and numerically demonstrate that the time delay signatures cannot be concealed in optical feedback semiconductor lasers. Whether single or double optical feedback, the time delay signatures can all be identified by the power spectrum analysis method. Furthermore, adjusting the feedback strength, the pumping current and the time-delay value, we find that the extraction of the time delay signatures still cannot be influenced. ? 1965-2012 IEEE.Accession Number: 20123715421166 -
Record 40 of
Title:Heat conductivity of particle stacking structured SiO2 porous film
Author(s):Xia, Zhilin(1,2); Wu, Yuting(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8206 Issue: DOI: 10.1117/12.910379 Published: 2012Abstract:Particle stacking structured SiO2 porous films were prepared by sol-gel method. A model has been established to analyze the heat conductivity of these films. It is assumed that the heat energy mainly transfers through particles and their contact points. In particle stacking structured materials, a particle contacts with twelve contiguous particles, and forms twelve heat conduction branches. This model is suit to the conditions that: the size of particles in the porous material is uniform; heat conductivity of particle skeleton is much greater than particle clearance; and all contact area between particles approximately equal. The results show that: heat conductivity of particles stacking porous material is anisotropic, material heat conductivity depends on that of the particle skeleton and the ratio between radiuses of particle contact area and particle itself. ? 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20120914804900 -
Record 41 of
Title:The stress relief mechanism in laser irradiating on porous films
Author(s):Xia, Zhilin(1,2); Wang, Hu(1); Xu, Qi(1)Source: Optics Communications Volume: 285 Issue: 1 DOI: 10.1016/j.optcom.2011.09.012 Published: January 1, 2012Abstract:Stress relief effect is believed to be the main reason why the porous structure films have high laser induced damage threshold. But there is little systematic theoretical investigation of this view. This essay adopts spherical coordinate model to calculate the temperature and stress distribution in the film and analyzes the local stress redistribution after phase transformation or crush happens. The influences of porosity and pore radius on stress redistribution have been studied. The results show that: for the case of only local crush occurrence, the changes of porosity and pore radius have little influence on the stress relief effect. For the films with low porosity, the formed thermal stress cannot be alleviated effectively. When local phase transformation happens, the permeation action of high pressure fluid can reduce the local high pressure in the phase transformation zone; on the other hand, it can make the high pressure fluid permeate to film's surface and cause surface tensile stress increase. The final effect is the competitive result of these two mechanisms. Overall, when the permeation action of phase transformation materials happens, the higher porosity or larger pore radius, the higher capability of films to resist laser damage. ? 2011 Elsevier B.V. All rights reserved.Accession Number: 20114514488531 -
Record 42 of
Title:All-fiber all-normal-dispersion passively mode-locked Yb-doped ring laser based on graphene oxide
Author(s):Li, Xiaohui(1,2); Liu, Meng(1); Yan, Zhiyu(1); Wang, Qijie(1); Wang, Yishan(2); Wang, Yonggang(3); Yu, Xia(4)Source: 2012 Photonics Global Conference, PGC 2012 Volume: Issue: DOI: 10.1109/PGC.2012.6458031 Published: 2012Abstract:We demonstrate an all-fiber all-normal-dispersion Yb-doped fiber laser that is passively mode locked by a graphene oxide (GO)-polymer. Because of good solution processing characteristic of the GO to polymer, a GO-polymer saturable absorber (SA) was successfully fabricated. Self-started mode-locking laser performance was investigated comprehensively at different cavity lengths, from 5, 24, to 94 m. The results showed that the pulse duration varies from hundreds of picoseconds to nanoseconds. In addition, the average output power of the mode-locked fiber laser can reach up to 500 mW. Furthermore, it was demonstrated that pulses with large chirps can be more easily amplified to reach high output power. ? 2012 IEEE.Accession Number: 20131016082254 -
Record 43 of
Title:Robust alternative minimization for matrix completion
Author(s):Lu, Xiaoqiang(1); Gong, Tieliang(2); Yan, Pingkun(1); Yuan, Yuan(1); Li, Xuelong(1)Source: IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics Volume: 42 Issue: 3 DOI: 10.1109/TSMCB.2012.2185490 Published: 2012Abstract:Recently, much attention has been drawn to the problem of matrix completion, which arises in a number of fields, including computer vision, pattern recognition, sensor network, and recommendation systems. This paper proposes a novel algorithm, named robust alternative minimization (RAM), which is based on the constraint of low rank to complete an unknown matrix. The proposed RAM algorithm can effectively reduce the relative reconstruction error of the recovered matrix. It is numerically easier to minimize the objective function and more stable for large-scale matrix completion compared with other existing methods. It is robust and efficient for low-rank matrix completion, and the convergence of the RAM algorithm is also established. Numerical results showed that both the recovery accuracy and running time of the RAM algorithm are competitive with other reported methods. Moreover, the applications of the RAM algorithm to low-rank image recovery demonstrated that it achieves satisfactory performance. ? 2012 IEEE.Accession Number: 20122115046892 -
Record 44 of
Title:Segmenting human from photo images based on a coarse-to-fine scheme
Author(s):Lu, Huchuan(1); Fang, Guoliang(1); Shao, Xinqing(1); Li, Xuelong(2)Source: IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics Volume: 42 Issue: 3 DOI: 10.1109/TSMCB.2011.2182048 Published: 2012Abstract:Human segmentation in photo images is a challenging and important problem that finds numerous applications ranging from album making and photo classification to image retrieval. Previous works on human segmentation usually demand a time-consuming training phase for complex shape-matching processes. In this paper, we propose a straightforward framework to automatically recover human bodies from color photos. Employing a coarse-to-fine strategy, we first detect a coarse torso (CT) using the multicue CT detection algorithm and then extract the accurate region of the upper body. Then, an iterative multiple oblique histogram algorithm is presented to accurately recover the lower body based on human kinematics. The performance of our algorithm is evaluated on our own data set (contains 197 images with human body region ground truth data), VOC 2006, and the 2010 data set. Experimental results demonstrate the merits of the proposed method in segmenting a person with various poses. ? 2012 IEEE.Accession Number: 20122115046896 -
Record 45 of
Title:Beyond spatial pyramids: A new feature extraction framework with dense spatial sampling for image classification
Author(s):Yan, Shengye(1); Xu, Xinxing(1); Xu, Dong(1); Lin, Stephen(2); Li, Xuelong(3)Source: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) Volume: 7575 LNCS Issue: PART 4 DOI: 10.1007/978-3-642-33765-9_34 Published: 2012Abstract:We introduce a new framework for image classification that extends beyond the window sampling of fixed spatial pyramids to include a comprehensive set of windows densely sampled over location, size and aspect ratio. To effectively deal with this large set of windows, we derive a concise high-level image feature using a two-level extraction method. At the first level, window-based features are computed from local descriptors (e.g., SIFT, spatial HOG, LBP) in a process similar to standard feature extractors. Then at the second level, the new image feature is determined from the window-based features in a manner analogous to the first level. This higher level of abstraction offers both efficient handling of dense samples and reduced sensitivity to misalignment. More importantly, our simple yet effective framework can readily accommodate a large number of existing pooling/coding methods, allowing them to extract features beyond the spatial pyramid representation. To effectively fuse the second level feature with a standard first level image feature for classification, we additionally propose a new learning algorithm, called Generalized Adaptive p -norm Multiple Kernel Learning (GA-MKL), to learn an adapted robust classifier based on multiple base kernels constructed from image features and multiple sets of pre-learned classifiers of all the classes. Extensive evaluation on the object recognition (Caltech256) and scene recognition (15Scenes) benchmark datasets demonstrates that the proposed method outperforms state-of-the-art image classification algorithms under a broad range of settings. ? 2012 Springer-Verlag.Accession Number: 20124415618870 -
Record 46 of
Title:Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics): Preface
Author(s):Wang, Fei(1); Shen, Dinggang(2); Yan, Pingkun(3); Suzuki, Kenji(4)Source: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) Volume: 7588 LNCS Issue: DOI: Published: 2012Abstract:nullAccession Number: 20124815738591 -
Record 47 of
Title:Parallelized evolutionary learning for detection of biclusters in gene expression data
Author(s):Huang, Qinghua(1); Tao, Dacheng(2); Li, Xuelong(3); Liew, Alan(4)Source: IEEE/ACM Transactions on Computational Biology and Bioinformatics Volume: 9 Issue: 2 DOI: 10.1109/TCBB.2011.53 Published: 2012Abstract:The analysis of gene expression data obtained from microarray experiments is important for discovering the biological process of genes. Biclustering algorithms have been proven to be able to group the genes with similar expression patterns under a number of experimental conditions. In this paper, we propose a new biclustering algorithm based on evolutionary learning. By converting the biclustering problem into a common clustering problem, the algorithm can be applied in a search space constructed by the conditions. To further reduce the size of the search space, we randomly separate the full conditions into a number of condition subsets (subspaces), each of which has a smaller number of conditions. The algorithm is applied to each subspace and is able to discover bicluster seeds within a limited computing time. Finally, an expanding and merging procedure is employed to combine the bicluster seeds into larger biclusters according to a homogeneity criterion. We test the performance of the proposed algorithm using synthetic and real microarray data sets. Compared with several previously developed biclustering algorithms, our algorithm demonstrates a significant improvement in discovering additive biclusters. ? 2012 IEEE.Accession Number: 20120614740197 -
Record 48 of
Title:Multivariate multilinear regression
Author(s):Su, Ya(1); Gao, Xinbo(2); Li, Xuelong(3); Tao, Dacheng(4)Source: IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics Volume: 42 Issue: 6 DOI: 10.1109/TSMCB.2012.2195171 Published: 2012Abstract:Conventional regression methods, such as multivariate linear regression (MLR) and its extension principal component regression (PCR), deal well with the situations that the data are of the form of low-dimensional vector. When the dimension grows higher, it leads to the under sample problem (USP): the dimensionality of the feature space is much higher than the number of training samples. However, little attention has been paid to such a problem. This paper first adopts an in-depth investigation to the USP in PCR, which answers three questions: 1) Why is USP produced? 2) What is the condition for USP, and 3) How is the influence of USP on regression. With the help of the above analysis, the principal components selection problem of PCR is presented. Subsequently, to address the problem of PCR, a multivariate multilinear regression (MMR) model is proposed which gives a substitutive solution to MLR, under the condition of multilinear objects. The basic idea of MMR is to transfer the multilinear structure of objects into the regression coefficients as a constraint. As a result, the regression problem is reduced to find two low-dimensional coefficients so that the principal components selection problem is avoided. Moreover, the sample size needed for solving MMR is greatly reduced so that USP is alleviated. As there is no closed-form solution for MMR, an alternative projection procedure is designed to obtain the regression matrices. For the sake of completeness, the analysis of computational cost and the proof of convergence are studied subsequently. Furthermore, MMR is applied to model the fitting procedure in the active appearance model (AAM). Experiments are conducted on both the carefully designed synthesizing data set and AAM fitting databases verified the theoretical analysis. ? 1996-2012 IEEE.Accession Number: 20124815729237