2011
2011
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Record 181 of
Title:High-power fiber laser amplifiers based on a new pump-coupling technology
Author(s):Zhao, Baoyin(1,2); Duan, Kailiang(1); Zhao, Wei(1); Zhang, Entao(1); Hui, Xiangyun(1,2)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 38 Issue: 7 DOI: 10.3788/CJL201138.0702014 Published: July 2011Abstract:By constructing the coupled-mode equations, the mode-coupling characteristics between the passive and active cores within a kind of composite structural fiber (CSF) are studied theoretically. By using the steady-state rate equations and the heat conductive equations, the gain characteristics and the temperature distribution of all-fiber laser amplifiers based on CSF are calculated and analyzed numerically. The results show that the mode-coupling characteristics depend on the coupled modes, the radius and the separation of the two cores of the CSF. Compared with the end-pumped fiber laser amplifiers, the amplifiers based on CSF have a slow pump light absorption and conversion, and thus, have low temperature distribution. This kind of new coupling-pump technology by using CSF is of apparent advantages. It can be used to solve the problem of high temperature of end-pumped fiber amplifiers, and thereby provides a new approach to design higher power fiber lasers and fiber amplifiers.Accession Number: 20113114207831 -
Record 182 of
Title:Preparation and properties of novel GeS2-Ga(In) 2S3-CuI chalcohalide glasses
Author(s):Zheng, X.(1); Chen, F.(3); Tao, H.(1); Guo, H.(2); Lin, C.(3); Gu, S.(1); Zhao, X.(1)Source: Journal of Optoelectronics and Advanced Materials Volume: 13 Issue: 1 DOI: Published: January 2011Abstract:Novel GeS2-Ga(In)2S3-CuI chalcohalide glasses were prepared successfully. These glasses have relatively high glass transition temperatures up to 452 °C but narrow glass-forming region, and a wide range of transmission approximately from 0.50 to 12.5μm. The structural evolvement of the glasses was studied by Raman spectroscopy. Finally, third-order optical nonlinearities were investigated utilizing Z-scan technique at the wavelength of 800nm. Both nonlinear refractive index n2 and nonlinear absorption coefficient β show an increasing tendency with increasing CuI content or substituting In for Ga, and structural dependency of n2 has also been discussed. A minimum figure of merit FOM = 2.237 was obtained.Accession Number: 20203409074747 -
Record 183 of
Title:Designing and selecting features for MR image segmentation
Author(s):Yang, Meijuan(1,2); Yuan, Yuan(1,2); Li, Xuelong(1,2); Yan, Pingkun(1,2)Source: 1st Asian Conference on Pattern Recognition, ACPR 2011 Volume: Issue: DOI: 10.1109/ACPR.2011.6166535 Published: 2011Abstract:Deformable models have obtained considerable success in medical image segmentation, due to its ability of capturing the shape variation of the target structure. Boundary feature is used to guide contour deformation, which plays an decisive part in deformable model based segmentation. However, it is still a challenging task to obtain a distinctive image feature to describe the boundaries, since boundaries are not necessarily in accordance with edges or ridges. Another challenge is to infer the shape for the given image appearance. In this paper, the anatomical structures from MR images are aimed to be segmented. First, a new normal vector feature profile (NVFP) is employed to describe the local image appearance of a contour point formed by a series of modified SIFT local descriptors along the normal direction of that point. Second, the shape of the target structure is inferred by matching two image appearances of the test image and learned image appearance. A new match function is designed to incorporate the new NVFP to deformable models. During the optimization procedure of the segmentation algorithm, the nearest neighbor approach is used to compute the displacement of each contour point to guide the global shape deformation. Experimental results on prostate and bladder MR images show that the proposed method has a better performance than the previous method. ? 2011 IEEE.Accession Number: 20122715188482 -
Record 184 of
Title:Optimization for limited angle tomography in medical image processing
Author(s):Lu, Xiaoqiang(1); Sun, Yi(1); Yuan, Yuan(2)Source: Pattern Recognition Volume: 44 Issue: 10-11 DOI: 10.1016/j.patcog.2010.12.016 Published: October-November 2011Abstract:This paper aims to reduce the problems of incomplete data in computed tomography, which happens frequently in medical image process and analysis, e.g., when the high-density region of objects can only be penetrated by X-rays at a limited angular range. As the projection data are available only in an angular range, the incomplete data problem can be attributed to the limited angle problem, which is an ill-posed inverse problem. Image reconstruction based on total variation (TV) reduces the problem and gives better performance on edge-preserving reconstruction; however, the artificial parameter can only be determined through considerable experimentation. In this paper, an effective TV objective function is proposed to reduce the inverse problem in the limited angle tomography. This novel objective function provides a robust and effective reconstruction without any artificial parameter in the iterative processes, using the TV as a multiplicative constraint. The results demonstrate that this reconstruction strategy outperforms some previous ones. ? 2011 Published by Elsevier Ltd.Accession Number: 20112514071849 -
Record 185 of
Title:Travelogue enriching and scenic spot overview based on textual and visual topic models
Author(s):Pang, Yanwei(1); Lu, Xin(1); Yuan, Yuan(2); Li, Xuelong(2)Source: International Journal of Pattern Recognition and Artificial Intelligence Volume: 25 Issue: 3 DOI: 10.1142/S0218001411008671 Published: May 2011Abstract:We consider the problem of enriching the travelogue associated with a small number (even one) of images with more web images. Images associated with the travelogue always consist of the content and the style of textual information. Relying on this assumption, in this paper, we present a framework of travelogue enriching, exploiting both textual and visual information generated by different users. The framework aims to select the most relevant images from automatically collected candidate image set to enrich the given travelogue, and form a comprehensive overview of the scenic spot. To do these, we propose to build two-layer probabilistic models, i.e. a text-layer model and image-layer models, on offline collected travelogues and images. Each topic (e.g. Sea, Mountain, Historical Sites) in the text-layer model is followed by an image-layer model with sub-topics learnt (e.g. the topic of sea is with the sub-topic like beach, tree, sunrise and sunset). Based on the model, we develop strategies to enrich travelogues in the following steps: (1) remove noisy names of scenic spots from travelogues; (2) generate queries to automatically gather candidate image set; (3) select images to enrich the travelogue; and (4) choose images to portray the visual content of a scenic spot. Experimental results on Chinese travelogues demonstrate the potential of the proposed approach on tasks of travelogue enrichment and the corresponding scenic spot illustration. ? 2011 World Scientific Publishing Company.Accession Number: 20112214018839 -
Record 186 of
Title:Poisson noise removal for X-ray pulsar integrated pulse profile
Author(s):Hu, Huijun(1,2); Zhao, Baosheng(1); Sheng, Lizhi(1,2); Yan, Qiurong(1,2); Yang, Hao(1,2); Chen, Baomei(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 31 Issue: 8 DOI: 10.3788/AOS201131.0804002 Published: August 2011Abstract:The photon detection model of X-ray pulsar and the construction of pulsar integrated pulse profile are discussed. The characteristics of pulse profile which is reconstructed by the way of photon counting are analyzed. A de-noising algorithm based on non-normalized Haar wavelet is proposed, and the optimal parameters for wavelet threshold function are derived based on Haar wavelet. The experimental study is done in the ground simulated experimental system for X-ray pulsar navigation. Experimental results show that the peak signal-to-noise ratio can be improved by at least 2 dB, and the accuracy of time-of-arrival (TOA) measurement is also improved, which is proved by Monte Carlo simulation.Accession Number: 20113714332382 -
Record 187 of
Title:Morphology of NaNdF4 nanocrystals from Nd(C3H 7COO)3·Phen and Nd(NO3) 3·Phen (Phen, 1,10-phenanthroline) as neodymium precursors
Author(s):Cui, Kai(1,2); Gao, Chao(3); Cui, Xiaoxia(1); She, Jiangbo(1); Peng, Bo(4); Wei, Wei(4)Source: Journal of Rare Earths Volume: 29 Issue: 1 DOI: 10.1016/S1002-0721(10)60399-7 Published: January 2011Abstract:A series of NaNdF4 nanocrystals was synthesized via a facile hydrothermal route with Nd(C3H7COO)3· Phen and Nd(NO3)3·Phen (Phen, 1,10-phenanthroline) as the Nd precursors. Distinct effect of the neutral donor ligand (Phen) on the morphology of NaNdF4 nanocrystals was demonstrated. When Nd(C 3H7COO)3·Phen was chosen and the hydrothermal reaction temperature was controlled at 220 °C, the NaNdF 4 nanocrystals with uniform short nanorod shape were obtained. The sizes of the as-prepared nanorods could be tuned by changing the hydrothermal temperatures. This method provided a useful way for the preparation of sodium rare-earth fluoride nanocrystals with controlled shapes and sizes. ? 2011 The Chinese Society of Rare Earths.Accession Number: 20110713659110 -
Record 188 of
Title:Optical image operation based on holographic polarization multiplexing of fulgide film
Author(s):Wang, Yingli(1); Yao, Baoli(1); Menke, Neimule(1); Chen, Yi(2); Fan, Meigong(2)Source: Chinese Optics Letters Volume: 9 Issue: SUPPL. 1 DOI: 10.3788/COL201109.S10302 Published: June 2011Abstract:Fulgide, a kind of thermally irreversible photochromic compound, can be used for polarization holographic recording owing to its photoinduced anisotropy and photochromic property under the irradiation of linear polarization light. In this letter, a new technique of optical image operation based on the polarization multiplexing scheme in the fulgide film is demonstrated, which can implement the readout of two individual orthogonal polarized images separately and the subtraction or summation of the two images by simply rotating a polarizer in front of the charge-coupled device (CCD) detector. ? 2011 Chinese Optics Letters.Accession Number: 20113214224372 -
Record 189 of
Title:Self-adaptive threshold tracking algorithm of infrared weak-small targets
Author(s):Xu, Zhaohui(1); Zhang, Yongkang(1); Tian, Yan(1); Tang, Huijun(1); Wei, Junxia(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8003 Issue: DOI: 10.1117/12.901208 Published: 2011Abstract:To detect IWST, foreign and domestic scholars put forward many meaningful detection methods. However, most of the algorithms are too much complex in the calculation to meet real-time and reliability requirements in practical application. A simple self-adaptive threshold algorithm to capture and track the IWST is presented in this paper. Testing results showed that algorithm not only effectively extract IWST and track it through the clouds in the sky background, but also has a strong robustness for the interference of background noises. ? 2011 SPIE.Accession Number: 20115214632143 -
Record 190 of
Title:A novel metric based on MCA for image quality
Author(s):He, Lihuo(1); Lu, Wen(1); Gao, Xinbo(1); Tao, Dacheng(2); Li, Xuelong(2)Source: International Journal of Wavelets, Multiresolution and Information Processing Volume: 9 Issue: 5 DOI: 10.1142/S0219691311004298 Published: September 2011Abstract:Considering that the Human Visual System (HVS) has different perceptual characteristics for different morphological components, a novel image quality metric is proposed by incorporating Morphological Component Analysis (MCA) and HVS, which is capable of assessing the image with different kinds of distortion. Firstly, reference and distorted images are decomposed into linearly combined texture and cartoon components by MCA respectively. Then these components are turned into perceptual features by Just Noticeable Difference (JND) which integrates masking features, luminance adaptation and Contrast Sensitive Function (CSF). Finally, the discrimination between reference and distorted images perceptual features is quantified using a pooling strategy before the final image quality is obtained. Experimental results demonstrate that the performance of the proposed prevails over some existing methods on LIVE database II. ? 2011 World Scientific Publishing Company.Accession Number: 20114414479980 -
Record 191 of
Title:Giant birefringence of periodic dielectric waveguides
Author(s):Zhang, Wenfu(1,2); Liu, Jihong(3); Huang, Wei-Ping(4); Zhao, Wei(1)Source: IEEE Photonics Journal Volume: 3 Issue: 3 DOI: 10.1109/JPHOT.2011.2154319 Published: June 2011Abstract:The giant (Δn > 1.5) and broadband achromatic birefringence is realized by periodic dielectric waveguides (PDWs), which benefit from low loss transmission, compact size, and simple structure. Based on the PDW, ultrabroadband achromatic (> 100 nm), low-order ultracompact (Accession Number: 20112414050317 -
Record 192 of
Title:Estimating patient-specific shape prior for medical image segmentation
Author(s):Zhang, Wuxia(1); Yan, Pingkun(1); Li, Xuelong(1)Source: Proceedings - International Symposium on Biomedical Imaging Volume: Issue: DOI: 10.1109/ISBI.2011.5872673 Published: 2011Abstract:Image segmentation is one of the key problems in medical image analysis. This paper presents a new statistical shape model for automatic image segmentation. In contrast to the previous model based segmentation methods, where shape priors are estimated from a general population-based shape model, our proposed method aims to estimate patient-specific shape priors to achieve more accurate segmentation by using manifold learning techniques. The proposed shape prior estimation method is incorporated into a deformable model based framework for image segmentation. The effectiveness of the proposed method has been demonstrated by the experiments on segmenting the prostate from MR images. ? 2011 IEEE.Accession Number: 20114414477638