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Record 121 of
Title:Application of optical coherence tomography in the detection of the mural
Author(s):Yang, Shanshan(1,2,3); Zhu, Rui(1,3); Mi, Lei(1); Cao, Yihui(1,2,3); Li, Qingyun(3)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 5 DOI: 10.3788/AOS201535.0511005 Published: May 10, 2015
Abstract:Based on the Michelson interferometer, optical coherence tomography (OCT) is a fast, non-contact, coherent optical imaging technology. OCT can image the internal microstructure underneath the surface. Archaeological objects are valuable and thus require nondestructive testing techniques. OCT, as a non-destructive analysis technique, is suitable for testing any part of the mural and other cultural relics. High resolution OCT images can provide the detailed information of the paint layer on the surface and the ground layer underneath the surface, which is elusive for traditional techniques. The technique of OCT is introduced and the verification experiment of the mural of Tang dynasty is carried out. From OCT images, defect information of the paint layer on the mural topside and structure underneath the surface can be seen. The information is of great help to the research and repair of the mural. OCT can be used in the research and repair of murals as a powerful tool for the researchers. ?, 2015, Chinese Optical Society. All right reserved.
Accession Number: 20152600979186
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Record 122 of
Title:The research of the light source for star simulator with automatic calibration and adjustable spectrum
Author(s):Li, Xiao-Ni(1,2); Wu, Cui-Gang(1); Zhao, Xin(3); Lu, Zhen-Hua(1); Xie, Lai-Yun(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 44 Issue: 5 DOI: 10.3788/gzxb20154405.0522003 Published: May 1, 2015
Abstract:In order to obtain the star simulator sources system of the adjustable spectrum with more color temperatures and more magnitudes and it can be calibrated automatically in a wide range of spectral bands. Embarking from the amplitude and colorimetry, This paper realize the automatic calibrating multispectral light star simulator system which the color temperature is continuous adjustable from 3900 K to 6500 K and the magnitudes is 1 MV adjustable in -1 MV~+6 MV with double integrating spheres in 400 nm~900 nm spectral range, The light system is based on the least squares method and the white LED are treated as the main body, a variety of different peak wavelength and narrow-band spectrum LEDs to compensate the objective spectrum. Finally, the source system and star simulator are completed and debugged in the laboratory, and the results are compared with the theoretical simulation values and standard visual magnitudes. The results show that the star simulator spectrum simulation error and magnitude error are within the range of ±10% and ±10% respectively and meet the stage star sensor needs, At the same time, In ensuring the stability of the control circuit, magnitude error can be within the range of ±5%. ?, 2015, Chinese Optical Society. All right reserved.
Accession Number: 20152500946859
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Record 123 of
Title:Fabrication and characterization of carbon/oxygen-implanted waveguides in Nd3+-doped phosphate glasses
Author(s):Liu, Chun-Xiao(1); Xu, Jun(2); Fu, Li-Li(3); Zheng, Rui-Lin(1); Zhou, Zhi-Guang(4); Li, Wei-Nan(4); Guo, Hai-Tao(4); Lin, She-Bao(5); Wei, Wei(1)
Source: Optical Engineering Volume: 54 Issue: 6 DOI: 10.1117/1.OE.54.6.067106 Published: June 1, 2015
Abstract:Optical planar waveguides in Nd3+-doped phosphate glasses are fabricated by a 6.0-MeV carbon ion implantation with a dose of 6.0 × 1014 ions/cm2 and a 6.0-MeV oxygen ion implantation at a fluence of 6.0 × 1014 ions/cm2, respectively. The guided modes and the corresponding effective refractive indices were measured by a modal 2010 prism coupler. The refractive index profiles of the waveguides were analyzed based on the stopping and range of ions in matter and the RCM reflectivity calculation method. The near-field light intensity distributions were measured and simulated by an end-face coupling method and a finite-difference beam propagation method, respectively. The comparison of optical properties between the carbon-implanted waveguide and the oxygen-implanted waveguide was carried out. The microluminescence and Raman spectroscopy investigations reveal that fluorescent properties of Nd3+ ions and glass microstructure are well preserved in the waveguide region, which suggests that the carbon/oxygen-implanted waveguide is a good candidate for integrated photonic devices. ?2015 Society of Photo-Optical Instrumentation Engineers.
Accession Number: 20152600970275
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Record 124 of
Title:A tilt-compensated Fourier transform spectrometer with an image rotator
Author(s):Wei, Ruyi(1,2); Yin, Bangsheng(3)
Source: Optics Communications Volume: 346 Issue: DOI: 10.1016/j.optcom.2015.02.028 Published: July 1, 2015
Abstract:Due to the moving plane mirror, tilt compensation is crucial and challenging in designing high precision Michelson-type interferometers. In this paper, we propose an optical configuration design using an image rotator and plane mirrors, including a movable double-sided mirror (DSM) to balance out the tilt of the mirror. We analysed the optical path differences (OPD) caused by the tilt of the DSM and their effects on interferogram under different tilt cases. Analyses demonstrate that this design is able to cancel out the offset of the OPD introduced by the tilt pitch angle. For different incident rays in parallel, the position of the tilt centre has no relationship with the change of the OPD, implying that the OPD could be self-compensated, and the modulation of the interferogram will not be degraded due to the tilt. This configuration effectively relaxes the requirements on the control of the precision of the postures of the moving mirror and thus may have broad applications. ? 2015 Elsevier B.V. All rights reserved.
Accession Number: 20150900577165
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Record 125 of
Title:Degradation of high power single emitter laser modules using nanosilver paste in continuous pulse conditions
Author(s):Yan, Haidong(1,2); Mei, Yunhui(1,2); Li, Xin(2); Zhang, Pu(3); Lu, Guo-Quan(4)
Source: Microelectronics Reliability Volume: 55 Issue: 12 DOI: 10.1016/j.microrel.2015.07.037 Published: December 1, 2015
Abstract:This paper is mainly reported to a pulse reliability investigation of high power single emitter laser modules with nanosilver paste. Comparative experiments in continuous pulse conditions for the laser modules packaged with nanosilver paste, indium and AuSn solders were conducted. The results indicate that the laser modules attached by nanosilver paste have a longer-term lifetime than those with indium and AuSn solders in continuous pulse conditions. Transient thermal behavior and coupled thermo-mechanical behavior in continuous pulse conditions are simulated by finite element method (FEM). A semi-empirical model based on Arrhenius relationship is established to provide relative reliability assessments for laser modules by combining with the simulating results. ? 2015 Elsevier Ltd. All rights reserved.
Accession Number: 20153001069180
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Record 126 of
Title:Low-rank representation for 3D hyperspectral images analysis from map perspective
Author(s):Yuan, Yuan(1); Fu, Min(1); Lu, Xiaoqiang(1)
Source: Signal Processing Volume: 112 Issue: DOI: 10.1016/j.sigpro.2014.06.018 Published: July 2015
Abstract:Hyperspectral images naturally stand as 3D data, which carry semantic information in remote sending applications. To well utilize 3D hyperspectral images, signal processing and learning techniques have been widely exploited, and the basis is to divide a given hyperspectral data into a set of semantic classes for analysis, i.e.; segmentation. To segment given hyperspectral data is an important and challenging research theme. Recently, to reduce the amount of human labor required to label samples in hyperspectral image segmentation, many approaches have been proposed and achieved good performance with a few labeled samples. However, most of them fail to exploit the high spectral correlation in distinct bands and utilize the spatial information of hyperspectral data. In order to overcome these drawbacks, a novel framework jointing the maximum a posteriori (MAP) model and low-rank representation (LRR) is proposed. In this paper, low-rank representation, conducted as a latent variables, can exploit the high spectral correlation in distinct bands and obtain a more compact and discriminative representation. On the other hand, a novel MAP framework is driven by using low-rank representation coefficient as latent variables, which will improve the probability that the closer pixels can be divided into the same class. The experiment results and quantitative analysis demonstrate that the proposed approach is effective and can obtain high segmentation accuracy compared with state-of-the-art approaches. ? 2014 Elsevier B.V.
Accession Number: 20150900586927
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Record 127 of
Title:Large-scale unsupervised hashing with shared structure learning
Author(s):Liu, Xianglong(1); Mu, Yadong(2); Zhang, Danchen(1); Lang, Bo(1); Li, Xuelong(3)
Source: IEEE Transactions on Cybernetics Volume: 45 Issue: 9 DOI: 10.1109/TCYB.2014.2360856 Published: September 1, 2015
Abstract:Hashing methods are effective in generating compact binary signatures for images and videos. This paper addresses an important open issue in the literature, i.e., how to learn compact hash codes by enhancing the complementarity among different hash functions. Most of prior studies solve this problem either by adopting time-consuming sequential learning algorithms or by generating the hash functions which are subject to some deliberately-designed constraints (e.g., enforcing hash functions orthogonal to one another). We analyze the drawbacks of past works and propose a new solution to this problem. Our idea is to decompose the feature space into a subspace shared by all hash functions and its complementary subspace. On one hand, the shared subspace, corresponding to the common structure across different hash functions, conveys most relevant information for the hashing task. Similar to data de-noising, irrelevant information is explicitly suppressed during hash function generation. On the other hand, in case that the complementary subspace also contains useful information for specific hash functions, the final form of our proposed hashing scheme is a compromise between these two kinds of subspaces. To make hash functions not only preserve the local neighborhood structure but also capture the global cluster distribution of the whole data, an objective function incorporating spectral embedding loss, binary quantization loss, and shared subspace contribution is introduced to guide the hash function learning. We propose an efficient alternating optimization method to simultaneously learn both the shared structure and the hash functions. Experimental results on three well-known benchmarks CIFAR-10, NUS-WIDE, and a-TRECVID demonstrate that our approach significantly outperforms state-of-the-art hashing methods. ? 2013 IEEE.
Accession Number: 20153401206302
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Record 128 of
Title:Annular force based variable curvature mirror aiming to realize non-moving element optical zooming
Author(s):Zhao, Hui(1); Xie, Xiaopeng(1,2); Wei, Jingxuan(3); Ren, Guorui(1); Pang, Zhihai(1); Xu, Liang(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9678 Issue: DOI: 10.1117/12.2197408 Published: 2015
Abstract:Recently, a new kind of optical zooming technique in which no moving elements are involved has been paid much attention. The elimination of moving elements makes optical zooming suitable for applications which has exacting requirements in space, power cost and system stability. The mobile phone and the space-borne camera are two typical examples. The key to realize non-moving elements optical zooming lies in the introduction of variable curvature mirror (VCM) whose radius of curvature could be changed dynamically. When VCM is about to be used to implement optical zoom imaging, two characteristics should be ensured. First, VCM has to provide large enough saggitus variation in order to obtain a big magnification ratio. Second, after the radius of curvature has been changed, the corresponding surface figure accuracy should still be maintained superior to a threshold level to make the high quality imaging possible. In this manuscript, based on the elasticity theory, the physical model of the annular force based variable curvature mirror is established and numerically analyzed. The results demonstrate that when the annular force is applied at the half-the-aperture position, the actuation force is reduced and a smaller actuation force is required to generate the saggitus variation and thus the maintenance of surface figure accuracy becomes easier during the variation of radius of curvature. Besides that, a prototype VCM, whose diameter and thickness are 100mm and 3mm respectively, have been fabricated and the maximum saggitus variation that could be obtained approaches more than 30 wavelengths. At the same time, the degradation of surface figure accuracy is weakly correlated to the curvature radius variation. ? 2015 SPIE.
Accession Number: 20161602271470
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Record 129 of
Title:A level set method with shape priors by using locality preserving projections
Author(s):Wang, Bin(1); Gao, Xinbo(1); Li, Jie(1); Li, Xuelong(2); Tao, Dacheng(3)
Source: Neurocomputing Volume: 170 Issue: DOI: 10.1016/j.neucom.2014.07.086 Published: December 25, 2015
Abstract:A novel level set method (LSM) with the constraint of shape priors is proposed to implement a selective image segmentation. Firstly, the shape priors are aligned by using image moment to deprive the spatial related information. Secondly, the aligned shape priors are projected into the subspace expanded by using locality preserving projection to measure the similarity between the shapes. Finally, a new energy functional is built by combing data-driven and shape-driven energy items to implement a selective image segmentation method. We assess the proposed method and some representative LSMs on the synthetic, medical and natural images, the results suggest that the proposed one is superior to the pure data-driven LSMs and the representative LSMs with shape priors. ? 2015 Elsevier B.V.
Accession Number: 20152701002846
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Record 130 of
Title:Bezier interpolation for 3-D freehand ultrasound
Author(s):Huang, Qinghua(1); Huang, Yanping(2); Hu, Wei(1); Li, Xuelong(3)
Source: IEEE Transactions on Human-Machine Systems Volume: 45 Issue: 3 DOI: 10.1109/THMS.2014.2374551 Published: June 1, 2015
Abstract:Freehand 3-D ultrasound (US) produces 3-D volume data of anatomical objects from a sequence of irregularly located 2-D B-mode US images (B-scans). In 3-D US, the voxel intensities are calculated by interpolating those pixels from raw B-scans. Current interpolation algorithms do not consider sparsity of the raw data and are time consuming in computation. In this paper, we aim to perform the 3-D reconstruction of freehand US with sparse raw data in a more efficient manner. A novel interpolation algorithm takes advantage of Bezier curves. A single sweep of raw B-scans is collected, and the third-order Bezier curves are employed for approximating the voxels located in a control window. In in vitro and in vivo experiments, a fetus phantom and a subject's forearm were scanned using the freehand 3-D US system and reconstructed using the proposed Bezier interpolation algorithm and three popular interpolation algorithms, respectively. The results showed that the proposed algorithm significantly outperformed the other three algorithms when the raw B-scans were relatively sparse and the interpolation error in gray level can be reduced by 0.515.07. The speed for 3-D reconstruction can be improved by 90.697.2 because a single third-order Bezier curve using four control points (i.e., the pixel points) is able to estimate more than four voxels, whereas the estimation of a voxel value often requires a number of pixels in conventional techniques. ? 2015 IEEE.
Accession Number: 20152100864459
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Record 131 of
Title:Effect of geometrical parameters on flow and heat transfer performances in multi-stream spiral-wound heat exchangers
Author(s):Lu, Xing(1); Zhang, Gaopeng(2); Chen, Yi-tung(3); Wang, Qiuwang(1); Zeng, Min(1)
Source: Applied Thermal Engineering Volume: 89 Issue: DOI: 10.1016/j.applthermaleng.2015.04.084 Published: 5 October 2015
Abstract:The influences of the changes in geometrical factors, including the space bar thickness, the tube pitch in the first layer, the tube external diameter, the number of layers and the centre core diameter on flow and heat transfer performances in multi-stream spiral-wound heat exchangers are numerical investigated. The shell-side and tube-side Nusselt number and pressure drop per unit length increase with the increase of number of layers, centre core diameter, and tube external diameter, but decrease with the increase of space bar thickness and tube pitch in the first layer. Quantitatively estimation of the affecting performances of these five geometrical parameters is implemented by using the Taguchi method, and the result shows that the contribution rate of them are more than 5%. Thus, the multivariate correlations with the main geometrical parameters considered are developed for shell-side Nusselt number and friction coefficient. ? 2015 Elsevier Ltd
Accession Number: 20152600979691
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Record 132 of
Title:Accurate normal and reflectance recovery using energy optimization
Author(s):Luo, Tao(1); Shen, Jianbing(1); Li, Xuelong(2)
Source: IEEE Transactions on Circuits and Systems for Video Technology Volume: 25 Issue: 2 DOI: 10.1109/TCSVT.2014.2333991 Published: February 1, 2015
Abstract:In this paper, we propose a novel energy optimization framework to accurately estimate surface normal and reflectance of an object from an input image sequence. Input images are captured from a fixed viewpoint under varying lighting conditions. In the proposed approach we combine photometric stereo and Retinex constraints into our energy function. To formulate inter-image constraints, shading information is added to the Lambertian model to account for shadows. For intra-image constraints, we moderate the strength of shading smoothness according to shadow mask and normal variations. By minimizing this energy function we are able to recover accurate surface normals and reflectance. Experimental results show that our approach yields more realistic normal map and accurate albedo map than the state-of-the-art uncalibrated photometric stereo algorithms. As for intrinsic image decomposition, results on the real and synthetic scenes show that the proposed approach outperforms previous ones. ? 1991-2012 IEEE.
Accession Number: 20151000604993
