2014
2014
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Record 97 of
Title:Study on spatial measurement accuracy of standard laser sourcenear-field parameters
Author(s):Duan, Yaxuan(1,2); Chen, Yongquan(1); Li, Kun(1); Zhao, Jianke(1); Long, Jiangbo(1); Gao, Limin(1)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 41 Issue: 3 DOI: 10.3788/CJL201441.0308003 Published: March 2014Abstract:In order to study on the spatial measurement accuracy of standard laser source near-field parameters, the theoretical model of near-field intensity distribution of standard laser source is established. The surface response non-uniformity correction program of the scientific grade CCD and calculation algorithm of laser near field is proposed. Using corrected scientific grade CCD and two-dimensional scanning device, the 50 mm × 50 mm soft-stop images of 1053 nm standard laser source are obtained by S-shaped scanning and capturing. The near-field image of standard laser source is got by the sub-aperture image mosaic. The test results of near-field intensity distribution are accordance with the theoretical results. The main difference between them is the high frequency components mainly caused by the roughness of off-axis parabolic mirror and random noise of the scientific grade CCD. The analysis of near-field parameters test results is that the uncertainty of modulation is 0.08 (k=2), and the uncertainty of contrast is 0.01 (k=2). The near-field measurement confidence of laser measurement system of National Science and Engineering is improved by the study results.Accession Number: 20141517568279 -
Record 98 of
Title:Effect of energy density on the machining character of C/SiC composites by picosecond laser
Author(s):Liu, Yongsheng(1); Wang, Chunhui(1); Li, Weinan(2); Yang, Xiaojun(2); Zhang, Qing(1); Cheng, Laifei(1); Zhang, Litong(1)Source: Applied Physics A: Materials Science and Processing Volume: 116 Issue: 3 DOI: 10.1007/s00339-013-8213-2 Published: September 2014Abstract:The effect of laser energy density on the machining character of C/SiC composites by picosecond laser was investigated using two machining modes: single ring line and helical lines scanning. For single ring line scanning mode, the width and depth of machining grooves increased nonlinearly with the increase of laser energy density. Moreover, periodic surface structures (ripples) were generated at relative low laser energy density and disappeared at high energy density. With the increasing energy density, the oxygen content of machining debris increased dramatically. For helical lines scanning mode, the depth of machining grooves increased nonlinearly with the increasing laser energy density. With the increasing energy density, the oxygen content of machining debris also increased dramatically. The machining character showed as nano-scale laser-induced ripples, pores, strip structures and bubble pits. Finally, micro-holes of high aspect ratio were obtained in the mode of helical lines scanning by removing multiple layers. ? 2013 Springer-Verlag Berlin Heidelberg.Accession Number: 20143518097849 -
Record 99 of
Title:Rejection of time-varying disturbances in inertial platform stabilizing system via unfalsified control
Author(s):Dong, Xiao-Kun(1,2); Cao, Jian-Zhong(1); Liu, Chen(1,2); Fan, Xin-Ming(1,2); Yang, Lei(1)Source: Kongzhi Lilun Yu Yingyong/Control Theory and Applications Volume: 31 Issue: 9 DOI: 10.7641/CTA.2014.31099 Published: September 1, 2014Abstract:The unfalsified control is a control method based on online data. This paper realizes the diversified operations of candidate controllers with the evolution strategy, and combines hysteresis switching algorithm with the switch controllers to achieve the adaptive PID controller. Because of the nonlinear time-varying disturbances in the inertial stabilizing system, we cannot obtain an accurate control model for the controlled object; however, by adopting the unfalsified control algorithm, we can stabilize the inertial stabilizing system with good results such as the azimuth errors less than 3.4 mrad and pitch errors less than 4.36 mrad.Accession Number: 20144600199842 -
Record 100 of
Title:Statistical quantization for similarity search
Author(s):Wang, Qi(1); Zhu, Guokang(2); Yuan, Yuan(2)Source: Computer Vision and Image Understanding Volume: 124 Issue: DOI: 10.1016/j.cviu.2014.03.002 Published: July 2014Abstract:Approximate nearest neighbor search has attracted much attention recently, which allows for fast query with a predictable sacrifice in search quality. Among the related works, k-means quantizers are possibly the most adaptive methods, and have shown the superiority on search accuracy than the others. However, a common problem shared by the traditional quantizers is that during the out-of-sample extension process, the naive strategy considers only the similarities in Euclidean space without taking into account the statistical and geometrical properties of the data. To cope with this problem, in this paper a novel approach is proposed by formulating a generalized likelihood ratio analysis. In particular, the proposed method takes a physically meaningful discrimination on the affiliations of the new samples with respect to the obtained Voronoi cells. This discrimination essentially imposes the measure of statistical consistency on out-of-sample extension. The experimental studies on two large data sets show that the proposed method is more effective than the benchmark algorithms. ? 2014 Elsevier Inc. All rights reserved.Accession Number: 20142417815385 -
Record 101 of
Title:Effect of energy density and feeding speed on micro-hole drilling in C/SiC composites by picosecond laser
Author(s):Liu, Yongsheng(1); Wang, Chunhui(1); Li, Weinan(2); Zhang, Litong(1); Yang, Xiaojun(2); Cheng, Guanghua(2); Zhang, Qing(1)Source: Journal of Materials Processing Technology Volume: 214 Issue: 12 DOI: 10.1016/j.jmatprotec.2014.07.016 Published: December 2014Abstract:The effect of energy density and feeding speed on micro-holes was investigated, which were machined in C/SiC composites by picosecond laser. Morphologies and elemental compositions of the machined holes in 2 mm and 3 mm thickness specimens were analyzed. The results indicated that both energy density and feeding speed had remarkable effect on the quality of micro-holes, especially on the exit side and cross-section of micro-holes. While the circularity of drilling holes on the entry side was affected by the energy density and feeding speed slightly. Additionally, the machining debris also played an important role in the quality of micro-holes. The micro-holes were consisted with three elements C, Si, and O, and those predominantly attributed to CC (sp2), CC (sp3) and SiO bonds. Moreover, the laser machining process was discussed, which was responsible for the formation of the debris. ? 2014 Elsevier B.V.Accession Number: 20143418093672 -
Record 102 of
Title:Improved joint demosaicking-zooming algorithm and its hardware design
Author(s):Li, Hua(1); Zhu, Bo(2,3)Source: Guangdianzi Jiguang/Journal of Optoelectronics Laser Volume: 25 Issue: 1 DOI: Published: January 2014Abstract:In order to obtain higher resolution full color image from Bayer CFA structure image directly, this paper presents a new joint demosaicking and zooming algorithm for digital camera equipped with a single CCD/CMOS sensor. We firstly extract GH and GV components of each pixel from mosaicking image through horizontal and vertical interpolations, respectively, and then we calculate and compare the horizontal chrominance gradient and the vertical one for choosing the missing G from GH and GV. By exploiting the high spectral-spatial correlations between color channels, we compute the two color difference images R-G and B-G to reduce the demosaicking and zooming errors. Next, we obtain the horizontal GzoomH and vertical GzoomV of each pixel, and also choose the missing zoomed Gzoom by calculating and comparing the chrominance gradient. Finally, the enlarged red and blue channels are obtained by adding the corresponding enlarged R-G and B-G color difference images to the enlarged green channel. Experimental results prove that the proposed algorithm outperforms some state-of-the-art demosaicking-zooming methods in both peak signal-to-noise ratio (PSNR) measure and visual quality. Furthermore, computational cost of the algorithm is low and it can be hardware processed in real time. Now, the proposed algorithm is implemented on Xilinx FPGA and used in camera system, and the perfect restoration quality and effectiveness meet the requirement of system design.Accession Number: 20141317523269 -
Record 103 of
Title:Modeling and analysis of ductility of brittle materials using indentation method
Author(s):Sun, Guoyan(1); Lu, Zhe(2); Bai, Jianming(1); Yu, Fangsu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9281 Issue: DOI: 10.1117/12.2069591 Published: 2014Abstract:Nowadays, many optical elements are fabricated by means of glass molding using hard and brittle inserts such as Silicon Carbide (SiC) and Silicon Nitride (Si3N4). However, for those hard-to-machine materials, the most feasible solution is still with ultra-precision grinding and following polishing. Hence, it is necessary and meaningful to study their plastic properties for the development of optical fabrication and ultra-precision manufacturing process. However, the conventional methods including compression test and indentation fracture mechanics are not sufficient to obtain the accurate parameters and still lack of reliable supporting of the machining process. To solve this problem, this paper presents a novel way to correlate the plastic properties to the indentation data using dimensional analysis for the two sorts of hard and brittle materials of SiC and Si3N4. Through integrating the data obtained by the indentation tests and the modeling method presented in this paper, stress-strain behavior, yield stress σy, yield strain Εy and strain hardening exponent n could be determined. The processing performance of these two materials reflected by the above parameters are consistent with the conclusions drawing from the indentation crack development under varying loads during the indentation test, which verifies the effectiveness and feasibility of the presented modeling method. ? 2014 SPIE.Accession Number: 20153101081042 -
Record 104 of
Title:Image super-resolution using multi-layer support vector regression
Author(s):Xu, Jie(1); Deng, Cheng(1); Gao, Xinbo(1); Tao, Dacheng(2); Li, Xuelong(3)Source: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings Volume: Issue: DOI: 10.1109/ICASSP.2014.6854715 Published: 2014Abstract:Existing support vector regression (SVR) based image superresolution (SR) methods always utilize single layer SVR model to reconstruct source image, which are incapable of restoring the details and reduce the reconstruction quality. In this paper, we present a novel image SR approach, where a multi-layer SVR model is adopted to describe the relationship between the low resolution (LR) image patches and the corresponding high resolution (HR) ones. Besides, considering the diverse content in the image, we introduce pixel-wise classification to divide pixels into different classes, such as horizontal edges, vertical edges and smooth areas, which is more conductive to highlight the local characteristics of the image. Moreover, the input elements to each SVR model are weighted respectively according to their corresponding output pixel's space positions in the HR image. Experimental results show that, compared with several other learning-based SR algorithms, our method gains high-quality performance. ? 2014 IEEE.Accession Number: 20143218038346 -
Record 105 of
Title:A Subwavelength Focusing Structure Composite of Nanoscale Metallic Slits Array With Patterned Dielectric Substrate
Author(s):Jia, Sen(1); Wu, Yiming(1); Wang, Xianhua(1); Wang, Ning(2)Source: IEEE Photonics Journal Volume: 6 Issue: 1 DOI: 10.1109/JPHOT.2014.2298406 Published: February 1, 2014Abstract:A novel plasmonic lens consisting of metallic nanoslits with a patterned dielectric substrate is proposed. In the structure, all metallic nanoslits have the same geometrical parameters and interspacing. The phase of incident light is modulated beforehand by the substrate before they bump on the metal slits. The surface plasmon polaritons (SPPs) wave excited by the modulated light will be focused after passing through the slits. Numerical simulation demonstrates that the size of the generated focal spot is very close to half wavelength. The overriding advantage of the proposed structure is that it significantly reduces the difficulty in fabrication while the focusing properties are comparable to the ones with filling materials in the slits. ? 2009-2012 IEEE.Accession Number: 20160902001594 -
Record 106 of
Title:Locality and similarity preserving embedding for feature selection
Author(s):Fang, Xiaozhao(1); Xu, Yong(1,2); Li, Xuelong(3); Fan, Zizhu(1); Liu, Hong(4); Chen, Yan(5)Source: Neurocomputing Volume: 128 Issue: DOI: 10.1016/j.neucom.2013.08.040 Published: March 27, 2014Abstract:Feature selection (FS) methods have commonly been used as a main way to select the relevant features. In this paper, we propose a novel unsupervised FS method, i.e., locality and similarity preserving embedding (LSPE) for feature selection. Specifically, the nearest neighbor graph is firstly constructed to preserve the locality structure of data points, and then this locality structure is mapped to the reconstruction coefficients such that the similarity among these data points is preserved. Moreover, the sparsity derived by the locality is also preserved. Finally, the low dimensional embedding of the sparse reconstruction is evaluated to best preserve the locality and similarity. We impose 2,1-norm on the transformation matrix to achieve row-sparsity, which allows us to select relevant features and learn the embedding simultaneously. The selected features have good stability due to the locality and similarity preserving, and more importantly, they contain natural discriminating information even if no class labels are provided. We present the optimization algorithm and analysis of convergence of the proposed method. The extensive experimental results show the effectiveness of the proposed method. ? 2013 Elsevier B.V.Accession Number: 20140517261353 -
Record 107 of
Title:Light flow model of coded aperture snapshot spectral imager
Author(s):Xie, Peiyue(1,2); Yang, Jianfeng(1); Xue, Bin(1); Wang, Hong(1,2); Song, Yansong(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9298 Issue: DOI: 10.1117/12.2070581 Published: 2014Abstract:Coded aperture snapshot spectral imager (CASSI) based on compressed sensing can capture a three-dimensional (3-D) data cube information in one snapshot without scanning, so it is a kind of novel spectral imaging technique with good prospects. In this paper, the data flow procession of two kind of CASSI were studied, which similarities and differences were depicted. The basic principle of the encoded representation of both spectral information and 2-D spatial information of a scene were presented. The numerical estimation techniques based on the compressive sensing theory were applied to reconstruct 3-D data cube. ? 2014 SPIE.Accession Number: 20150800546076 -
Record 108 of
Title:Integrate the original face image and its mirror image for face recognition
Author(s):Xu, Yong(1,2); Li, Xuelong(3); Yang, Jian(4); Zhang, David(5)Source: Neurocomputing Volume: 131 Issue: DOI: 10.1016/j.neucom.2013.10.025 Published: May 5, 2014Abstract:The face almost always has an axis-symmetrical structure. However, as the face usually does not have an absolutely frontal pose when it is imaged, the majority of face images are not symmetrical images. These facts inspire us that the mirror image of the face image might be viewed as a representation of the face with a possible pose opposite to that of the original face image. In this paper we propose a scheme to produce the mirror image of the face and integrate the original face image and its mirror image for representation-based face recognition. This scheme is simple and computationally efficient. Almost all the representation-based classification methods can be improved by this scheme. The underlying rationales of the scheme are as follows: first, the use of the mirror image can somewhat overcome the misalignment problem of the face image in face recognition. Second, it is able to somewhat eliminate the side-effect of the variation of the pose and illumination of the original face image. The experiments show that the proposed scheme can greatly improve the accuracy of the representation-based classification methods. The proposed scheme might be also helpful for improving other face recognition methods. ? 2013 Elsevier B.V.Accession Number: 20140817363951