2015

• Record 445 of
  
  Title:Scene Recognition by Manifold Regularized Deep Learning Architecture
  
  Author(s):Yuan, Yuan(1); Mou, Lichao(1); Lu, Xiaoqiang(1)
  Source: IEEE Transactions on Neural Networks and Learning Systems  Volume: 26  Issue: 10  DOI: 10.1109/TNNLS.2014.2359471  Published: October 1, 2015  
  Abstract:Scene recognition is an important problem in the field of computer vision, because it helps to narrow the gap between the computer and the human beings on scene understanding. Semantic modeling is a popular technique used to fill the semantic gap in scene recognition. However, most of the semantic modeling approaches learn shallow, one-layer representations for scene recognition, while ignoring the structural information related between images, often resulting in poor performance. Modeled after our own human visual system, as it is intended to inherit humanlike judgment, a manifold regularized deep architecture is proposed for scene recognition. The proposed deep architecture exploits the structural information of the data, making for a mapping between visible layer and hidden layer. By the proposed approach, a deep architecture could be designed to learn the high-level features for scene recognition in an unsupervised fashion. Experiments on standard data sets show that our method outperforms the state-of-the-art used for scene recognition. © 2012 IEEE.
  Accession Number: 20154201393491
• Record 446 of
  
  Title:MR image super-resolution via manifold regularized sparse learning
  
  Author(s):Lu, Xiaoqiang(1); Huang, Zihan(1); Yuan, Yuan(1)
  Source: Neurocomputing  Volume: 162  Issue:   DOI: 10.1016/j.neucom.2015.03.065  Published: August 25, 2015  
  Abstract:Single image super-resolution (SR) has been shown useful in Magnetic Resonance (MR) image based diagnosis, where the image resolution is still limited. The basic goal of single image SR is to produce a high-resolution (HR) image from corresponding low-resolution (LR) image. However, most existing SR algorithms often fail to: (1) reflect the intrinsic structure between MR images and (2) exploit the intra-patient information of MR images. In fact, MR images are more likely to vary along a low dimensional submanifold, which can be embedded in the high dimensional space. It has also been shown that the structure information of MR images and the priors of the MR images of different modality are important for improving the image resolution. To take full advantage of manifold structure information and intra-patient prior of MR images, a novel single image super-resolution algorithm for MR images is proposed in this paper. Compared with the existing works, the proposed algorithm has the following merits: (1) the proposed sparse coding based algorithm integrates manifold constraints to handle the inverse problem in MR image SR; (2) the manifold structure of the intra-patient MR image is considered for image SR; and (3) the topological structure of the intra-patient MR image can be preserved to improve the reconstructed result. Experiments show that the proposed algorithm is more effective than the state-of-the-art algorithms. © 2015 Elsevier B.V.
  Accession Number: 20151700785830
• Record 447 of
  
  Title:Subwavelength beam focusing via multiple-metal slits arranged along a triangle surface
  
  Author(s):Jia, Sen(1,2); Wu, Yiming(2); Si, Jinhai(1); Chen, Feng(1); Hou, Xun(1)
  Source: Optics Communications  Volume: 355  Issue:   DOI: 10.1016/j.optcom.2015.06.024  Published: July 27, 2015  
  Abstract:Abstract A compact plasmonic structure is proposed to actualize the subwavelength beam focusing, through a metal slit array arranged along a triangular or trapezium surface profile. The incident light passes through the metal slits in the form of surface plasmon polaritons (SPPs) and then scattered into radiation fields. The constructive interference of radiation fields from individual slits with different depths and widths gives rise to beam focusing. The advantages of the proposed plasmonic lens are having a much smaller lateral dimension and broad working wavelength range. This is of importance for realizing densely integrated photonic circuits. The finite-difference time-domain (FDTD) method is employed to verify the proposed design. The simulation results indicate that the focal spot is beyond the diffraction limit. © 2015 Elsevier B.V.
  Accession Number: 20153101083336
• Record 448 of
  
  Title:Plasmon-induced transparency in terahertz planar metamaterials
  
  Author(s):Chen, Xu(1,2); Fan, Wen-Hui(1)
  Source: Optics Communications  Volume: 356  Issue:   DOI: 10.1016/j.optcom.2015.07.063  Published: August 3, 2015  
  Abstract:Abstract A planar metamaterial structure with plasmon-induced transparency effect in terahertz region is proposed and systematic numerical study is presented in this paper. The metamaterial structure is comprised of two different spilt-ring resonators in the same plane. With the destructive interference coupling between these two split-ring resonators, the proposed metamaterial structure exhibits a large transparency window within a broad absorption spectra. Moreover, the origin of transparency window with extremely low absorption and strong dispersion is clarified by two coupled Lorentzian resonators analytical model, and verified by accurate simulation of the electromagnetic wave propagation in the metamaterial structure. The proposed metamaterial opens up the avenue to design micro-sized functional devices used in switching, modulation, and slowing down terahertz waves. © 2015 Elsevier B.V.
  Accession Number: 20153101104384
• Record 449 of
  
  Title:Spatiotemporal evolution of a cosine-modulated stationary field and Kerr frequency comb generation in a microresonator
  
  Author(s):Hu, Xiaohong(1,2); Liu, Yuanshan(1); Xu, Xin(1,2); Feng, Ye(1,2); Zhang, Wenfu(1); Wang, Weiqiang(1,2); Song, Jiazheng(1,2); Wang, Yishan(1); Zhao, Wei(1)
  Source: Applied Optics  Volume: 54  Issue: 29  DOI: 10.1364/AO.54.008751  Published: October 10, 2015  
  Abstract:Based on the normalized spatiotemporal Lugiato-Lefever equation, the evolutions of cosine-modulated stationary fields relating to the generation of single-free spectral range (FSR) or multi-FSR Kerr frequency combs in a microresonator with anomalous dispersion are studied numerically. The research results show that a single-FSR comb arises when a dissipative soliton pulse or multiple nonequidistant soliton pulses form in the cavity. Compared with the smooth and regular spectral structure of a single soliton pulse, the comb corresponding to the uneven distribution of multiple soliton pulses exhibits a complex and irregular profile. When the stable intracavity field consists of a "roll" Turing pattern or N(N > 1) evenly distributed soliton pulses separated by 2π/N, multi-FSR combs can be generated. In the case of the "roll" Turing pattern solution, it is found that third-order dispersion could modify the comb mode spacing and decrease the intensity of high-order comb modes. For the situation of multiple soliton pulse generation, the simulation results indicate that both the number and locations of the soliton pulses can be actively controlled through the careful selection of modulation frequency. In addition, for the selected cosine-modulated initial field profile, only those modes with the mode numbers being equal to an integer multiple of N can be greatly amplified by the parametric gain during propagation in the microresonator. This process eventually leads to the formation of a N-FSR frequency comb. © 2015 Optical Society of America.
  Accession Number: 20170603334032
• Record 450 of
  
  Title:Semi-supervised change detection method for multi-temporal hyperspectral images
  
  Author(s):Yuan, Yuan(1); Lv, Haobo(1); Lu, Xiaoqiang(1)
  Source: Neurocomputing  Volume: 148  Issue:   DOI: 10.1016/j.neucom.2014.06.024  Published: January 19, 2015  
  Abstract:Change detection is one of the most important open topics for multi-temporal remote sensing technology to observe the earth. Recently, many methods are proposed to detect the land-cover change information by multi-temporal hyperspectral images. However, many existing traditional change detection methods failed to utilize the spectral information effectively. Hence the models are not robust enough for more widely applications with "noise" bands. In this case, a semi-supervised distance metric learning method is proposed to detect the change areas by abundant spectral information of hyperspectral image under the "noisy" condition. This paper focuses on semi-supervised change detection method, and proposes a new distance metric learning framework for change detection in "noisy" condition with three mainly contributions: (1) Distance metric learning is demonstrated to be an effective method for revealing the change information by high spectral features. (2) An evolution regular framework is utilized to handle change detection under a "noisy" condition without removing any noise bands, which is impacted by atmosphere (or water) and always removed manually in other literatures. (3) A semi-supervised Laplacian Regularized Metric Learning method is exploited to tackle the ill-posed sample problem, and large unlabeled data is exploited in our method. The proposed method is performed on two multi-temporal hyperspectral datasets. Experimental results show that the proposed method outperforms the state-of-the-art change detection methods under both "ideal" and "noisy" conditions. © 2014 Elsevier B.V.
  Accession Number: 20143600016981
• Record 451 of
  
  Title:Trapping of Rayleigh spheroidal particles by highly focused radially polarized beams
  
  Author(s):Li, Manman(1,2); Yan, Shaohui(1); Yao, Baoli(1); Lei, Ming(1); Yang, Yanlong(1); Min, Junwei(1); Dan, Dan(1)
  Source: Journal of the Optical Society of America B: Optical Physics  Volume: 32  Issue: 3  DOI: 10.1364/JOSAB.32.000468  Published: March 1, 2015  
  Abstract:The optical forces and intrinsic optical torque of a highly focused radially polarized beam on a Rayleigh spheroidal particle are calculated with the dipole approximation. Numerical results show that the maximal trapping forces depend strongly on the orientation of the particle, and the torque is always perpendicular to the plane containing the major axis of the spheroid and the optical axis. As a result of optical mechanical and torque equilibrium, the spheroidal particle will stay at the focus with its major axis of the spheroid parallel to the optical axis. © 2015 Optical Society of America.
  Accession Number: 20151100625419
• Record 452 of
  
  Title:Accurate frequency estimator for optical coherent M-PSK system based on FFT and multiple signal classification algorithm
  
  Author(s):Zhang, Kewei(1,2); Wang, Wei(1); Zhao, Wei(1); Xie, Xiaoping(1)
  Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering  Volume: 44  Issue: 5  DOI:   Published: May 25, 2015  
  Abstract:For optical coherent M-ary phase-shift-keying (M-PSK) system, the frequency offset algorithm based on differential phase or FFT maximization which was widely used is difficult to achieve MHz estimation error when the data length is short, which is difficult for the following carrier phase estimation to recover the data. To meet the needs of high accuracy and real-time performance for frequency offset estimation in the M-PSK system, a frequency estimator based on fast Fourier transform and multiple signal classification (MUSIC) was proposed and investigated. For the first time, MUSIC algorithm was used in this area. The proposed algorithm is accurate especially when the data length is short. The principle and flowchart were proposed to illustrate the algorithm. Numerical simulations of 20-Gbaud QPSK coherent systems were carried out to demonstrate this algorithm. ©, 2015, Chinese Society of Astronautics. All right reserved.
  Accession Number: 20153501209545
• Record 453 of
  
  Title:Environmental-adaptability analysis of an all polarization-maintaining fiber-based optical frequency comb
  
  Author(s):Feng, Ye(1,2,3); Xu, Xin(1,2); Hu, Xiaohong(1,2); Liu, Yuanshan(1); Wang, Yishan(1); Zhang, Wei(1); Yang, Zhi(1); Duan, Lina(1); Zhao, Wei(1); Cheng, Zhao(4)
  Source: Optics Express  Volume: 23  Issue: 13  DOI: 10.1364/OE.23.017549  Published: 2015  
  Abstract:We demonstrate an all polarization-maintaining (PM) fiberbased optical frequency comb and provide the detailed environmental stability analysis results. The frequency comb has been built by commercial available PM fiber completely, and its static uncertainty in optical domain is 350 Hz in 1 s when referenced to a low noise oven controlled crystal oscillator. The acoustic resonant frequencies of the system have been measured. It is proved that acoustic-vibration induced phase noise could be eliminated by low pass vibration-isolation structure. Further, the existence of the optimum working temperature is illustrated. At this temperature (289.6 K), the out-loop integrated phase noise of frand the temperature-drift induced instability of fCEOreach the lowest level 31.6 μrad and 0 kHz/(mW·K) respectively. Finally, the system is proved to be stable under different humidity (18% ∼80%) by a 240-day-long record of the fCEO. © 2015 Optical Society of America.
  Accession Number: 20153701273343
• Record 454 of
  
  Title:Influence of laser linewidth and polarization modulator length on polarization shift keying for free space optical communication
  
  Author(s):Han, Biao(1,2); Zhao, Wei(1); Xie, Xiaoping(1); Su, Yulong(1,2); Wang, Wei(1); Hu, Hui(1)
  Source: Optics Express  Volume: 23  Issue: 7  DOI: 10.1364/OE.23.008639  Published: April 6, 2015  
  Abstract:Modulating signal with polarization modulator (PolM) is the simplest method for polarization shift keying (PolSK) in free space optical communication. However, this method has an intrinsic drawback on degree of polarization (DOP) reduction for the existence of polarization mode dispersion (PMD) in PolM. In this work, we analyze this change of DOP and its influence on PolSK using coherency matrix. We demonstrate that the decrease of DOP after PolM will generate extra loss and bit error ratio (BER) for PolSK communication, while this loss and BER will aggravate with the increase of laser linewidth and PolM length. For a practical PolSK system, laser linewidth should be less than 0.008nm. © 2015 Optical Society of America.
  Accession Number: 20151700776126
• Record 455 of
  
  Title:Curved optical tubes in a 4Pi focusing system
  
  Author(s):Yan, Shaohui(1); Yu, Xianghua(1,2); Li, Manman(1,2); Yao, Baoli(1)
  Source: Optics Express  Volume: 23  Issue: 17  DOI: 10.1364/OE.23.022890  Published: August 24, 2015  
  Abstract:We demonstrate the possibility of creating curved optical tubes in a 4Pi focusing system. The focal fields of such optical tubes have interesting properties: the energy is concentered in the neighborhood of a prescribed three-dimensional (3D) curve while the cross section is of hollow shape. The creation of these optical tubes is based on the annular focal spot of a vortex beam, which is employed as a building block. An optical tube is thus obtained by covering the central-axis curve of the tube by various such building blocks. Each building block has a certain orientation and position, realized by a rotation plus a certain translation. The spatial spectrum (the input field as well) of the optical tube is obtained by linearly superposing the spectrum of each transformed building block. The curve is rather arbitrary. Three examples of optical tubes: a torus, a solenoid and a trefoil knot are given, showing a good agreement with the expected results. © 2015 Optical Society of America.
  Accession Number: 20160701921752