Record 1 of 275

Title: SCECam: a spherical compound eye camera for fast location and recognition of objects at a large field of view

Author(s): Shi, CY (Shi, Chengyong); Wang, YY (Wang, Yuanyuan); Liu, CY (Liu, Chenyang); Wang, TS (Wang, Taisheng); Zhang, HX (Zhang, Hongxin); Liao, WX (Liao, Wuxia); Xu, ZJ (Xu, Zhijun); Yu, WX (Yu, Weixing)

Source: OPTICS EXPRESS  Volume: 25  Issue: 26  Pages: 32333-32345  DOI: 10.1364/OE.25.032333  Published: DEC 25 2017  

Abstract: In recent years, the compound eye imaging system has attracted great attention due to its fascinating optical features such as large field of view (FOV), small volume and high acuity to moving objects. However, it is still a big challenge to fabricate such a whole system due to the mismatch between the spherical compound eye imaging element and the planar imaging sensor. In this work, we demonstrate a kind of hemispherical compound eye camera (SCECam) which analogs the eye of the fruit fly. The SCECam consists of three sub-systems, a hemispherical compound eye, an optical relay system and a commercial CMOS imaging sensor. By introducing an intermediate optical relay system, the curved focal plane after the compound eye can be transformed and projected onto the planar focal plane of the imaging sensor. In this way, the SCECam can realize a large FOV (up to 122.4 degrees) with 4400 ommatidia, which makes it possible to detect and locate fast moving objects at a very fast speed. It is calculated that the recognition speed of the SCECam is two to three orders of magnitude higher than those conventional methods such as the Canny and Log edge-detection methods. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Accession Number: WOS:000418893200010

Author Identifiers:

ISSN: 1094-4087

Record 2 of 275

Title: Theoretical research of influence of laser intensity fluctuation on imaging quality degradation of coherent field

Author(s): Cheng, ZY (Cheng Zhi-Yuan); Ma, CW (Ma Cai-Wen); Ma, Q (Ma Qing)

Source: ACTA PHYSICA SINICA  Volume: 66  Issue: 24  Article Number: 244202  DOI: 10.7498/aps.66.244202  Published: DEC 20 2017  

Abstract: The laser coherent field imaging system emits multiple beams of laser from earth to space, and laser scans remote space target by passing through turbulence atmosphere. Multi-beam laser intensity fluctuation caused by atmosphere turbulence is a key factor affecting high-resolution imaging quality of the coherent field imaging system. Aiming at solving the problem of imaging quality degradation caused by laser intensity fluctuation error, we discuss the mechanism of laser intensity fluctuation error influencing the imaging quality of laser coherent field high-resolution imaging system. The theoretical model about the relationship between laser intensity fluctuation factor and imaging quality is proposed for the first time. Firstly, the laser echo field signal error induced by laser intensity amplitude fluctuation factor is deduced according to laser transmitting atmosphere theory. Then adopting multi-beam phase closure arithmetic, the phase closure coefficient error is derived from the laser intensity fluctuation factor and laser echo field signal. The mechanism of disturbed laser echo signal influencing phase closure coefficient is investigated in detail. In the following, based on reconstructed spectrum theory, the model of imaging frequency spectrum error propagation, caused by laser intensity fluctuation factor, is proposed. Finally, we reveal the mechanism of laser intensity amplitude fluctuation factor influencing reconstructed imaging frequency spectrum and imaging quality. The correctness and validity of the theoretical model are verified in simulation experiment. In the three-beam laser coherent field imaging simulation experiment, the imaging quality is evaluated by the Strehl ratio of the image. Experimental result shows that the Strehl ratio is only related to the light intensity fluctuation of one of the three beams of laser, and the greater the fluctuation of laser intensity, the more serious the degradation of imaging quality is. The research draws the conclusion that the reconstructed imaging frequency spectrum and image quality are mainly affected by the laser intensity fluctuation of the second beam in the three-beam phase closure algorithm, regardless of other two laser intensity fluctuations. Thus, in order to restrain the degradation of imaging quality caused by laser intensity fluctuation, we only need to keep stable the laser intensity of the second beam but not all of the laser beams. In this paper, we reveal the mechanism of laser intensity fluctuation affecting high-resolution imaging quality in the three-beam laser coherent field imaging system. The research provides a theoretical basis for analyzing imaging quality degradation from the laser intensity fluctuation caused by atmospheric turbulence, and reasonably assigning the light intensity stability of multi-beam laser emitter to improve the imaging quality in laser coherent field imaging system.

Accession Number: WOS:000425270000007

ISSN: 1000-3290

Record 3 of 275

Title: Target Detection of Quantum Illumination Receiver Based on Photon-subtracted Entanglement State

Author(s): Chi, J (Chi, Jiao); Liu, HJ (Liu, HongJun); Huang, N (Huang, Nan); Wang, ZL (Wang, ZhaoLu)

Source: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN  Volume: 86  Issue: 12  Article Number: 124402  DOI: 10.7566/JPSJ.86.124402  Published: DEC 15 2017  

Abstract: We theoretically propose a quantum illumination receiver based on the ideal photon-subtracted two-mode squeezed state (PSTMSS) to efficiently detect the noise-hidden target. This receiver is generated by applying an optical parametric amplifier (OPA) to the cross correlation detection. With analyzing the output performance, it is found that OPA as a preposition technology of the receiver can contribute to the PSTMSS by significantly reducing the error probability than that of the general two-mode squeezed state (TMSS). Comparing with TMSS, the signal-to-noise ratio of quantum illumination based on ideal PSTMSS and OPA is improved more than 4 dB under an optimal gain of OPA. This work may provide a potential improvement in the application of accurate target detection when two kinds of resource have the identical real squeezing parameter.

Accession Number: WOS:000416919700025

Author Identifiers:

ISSN: 0031-9015

Record 4 of 275

Title: Demonstration of a mid-infrared NO molecular Faraday optical filter

Author(s): Wu, KJ (Wu, Kuijun); Feng, YT (Feng, Yutao); Li, J (Li, Juan); Yu, GB (Yu, Guangbao); Liu, LM (Liu, Linmei); Xiong, YH (Xiong, Yuanhui); Li, FQ (Li, Faquan)

Source: OPTICS EXPRESS  Volume: 25  Issue: 25  Pages: 30916-30930  DOI: 10.1364/OE.25.030916  Published: DEC 11 2017  

Abstract: A molecular Faraday optical filter (MFOF) working in the mid-infrared region is realized for the first time. NO molecule was used as the working material of the MFOF for potential applications in atmospheric remote sensing and combustion diagnosis. We develop a complete theory to describe the performance of MFOF by taking both Zeeman absorption and Faraday rotation into account. We also record the Faraday rotation transmission (FRT) signal using a quantum cascade laser over the range of 1,820 cm(-1) to 1,922 cm(-1) and calibrate it by using a 101.6 mm long solid germanium etalon with a free spectral range of 0.012 cm(-1). Good agreement between the simulation results and experimental data is achieved. The NO-MFOF's transmission characteristics as a function of magnetic field and pressure are studied in detail. Both Comb-like FRT spectrum and single branch transmission spectrum are obtained by changing the magnetic field. The diversity of FRT spectrum expands the range of potential applications in infrared optical remote sensing. This filtering method can also be extended to the lines of other paramagnetic molecules. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Accession Number: WOS:000417591100010

PubMed ID: 29245771

ISSN: 1094-4087

Record 5 of 275

Title: Simultaneous, real-time, chromatic polarimetric imaging technology with full-polarization-state detection

Author(s): Ju, HJ (Ju Hai-Juan); Liang, J (Liang Jian); Zhang, WF (Zhang Wen-Fei); Bai, ZF (Bai Zhao-Feng); Ren, LY (Ren Li-Yong); Qu, ES (Qu En-Shi)

Source: JOURNAL OF INFRARED AND MILLIMETER WAVES  Volume: 36  Issue: 6  Pages: 744-748  DOI: 10.11972/j.issn.1001-9014.2017.06.018  Published: DEC 2017  

Abstract: As a new kind of optical imaging technology, polarimetric imaging can efficiently increase the detection dimension of the information by detecting the polarization properties of the optical wave. This is useful for obtaining the target information comprehensively and accurately. Firstly, the method of polarization imaging detecting was introduced and the typical polarization imaging systems are reviewed in this paper. Then, based on Stokes Vector, a simultaneous, real-time, division of aperture chromatic polarimetric imaging camera with full-polarization-state detection was introduced in detail. Finally, the experimental results of full polarimetric imaging and polarimetric dehazing imaging using this camera were demonstrated. The experimental results indicate that the polarimetric imaging technology of full polarization states simultaneous detecting has obvious advantages on developing the detecting distance and acquiring the detail features, so it can provide important supplement for modern optical imaging system.

Accession Number: WOS:000419930500018

ISSN: 1001-9014

Record 6 of 275

Title: Hundred Micro-Joules Level High Power Chirped Pulse Amplification of Femtosecond Laser Based on Single Crystal Fiber

Author(s): Li, F (Li, Feng); Yang, Z (Yang, Zhi); Lv, ZG (Lv, Zhiguo); Hu, XH (Hu, Xiaohong); Wei, YF (Wei, Yufeng); Li, QL (Li, Qianglong); Tang, SK (Tang, Shukuai); Wang, YS (Wang, Yishan); Yang, XJ (Yang, Xiaojun); Zhao, W (Zhao, Wei)

Source: IEEE PHOTONICS JOURNAL  Volume: 9  Issue: 6  Article Number: 1507307  DOI: 10.1109/JPHOT.2017.2780197  Published: DEC 2017  

Abstract: We demonstrate a hundred micro-Joules level femtosecond laser system based on a compact and simple two-stage Yb:YAG single crystal fiber chirped pulse amplification system which delivers compressed power of 15.57 W, pulse width of 715 fs. The different amplification performance with different input seed power is experimentally studied. A maximum direct amplified power output of 44 W at 100 kHz is obtained for an input seed power of 12 W. To the best of our knowledge, this is the highest average power of femtosecond laser based on single crystal fiber at hundred micro-Joules energy level.

Accession Number: WOS:000418416600001

Author Identifiers:

ISSN: 1943-0655

eISSN: 1943-0647

Record 7 of 275

Title: Constrained Low-Rank Learning Using Least Squares-Based Regularization

Author(s): Li, P (Li, Ping); Yu, J (Yu, Jun); Wang, M (Wang, Meng); Zhang, LM (Zhang, Luming); Cai, D (Cai, Deng); Li, XL (Li, Xuelong)

Source: IEEE TRANSACTIONS ON CYBERNETICS  Volume: 47  Issue: 12  Pages: 4250-4262  DOI: 10.1109/TCYB.2016.2623638  Published: DEC 2017  

Abstract: Low-rank learning has attracted much attention recently due to its efficacy in a rich variety of real-world tasks, e.g., subspace segmentation and image categorization. Most low-rank methods are incapable of capturing low-dimensional subspace for supervised learning tasks, e.g., classification and regression. This paper aims to learn both the discriminant low-rank representation (LRR) and the robust projecting subspace in a supervised manner. To achieve this goal, we cast the problem into a constrained rank minimization framework by adopting the least squares regularization. Naturally, the data label structure tends to resemble that of the corresponding low-dimensional representation, which is derived from the robust subspace projection of clean data by low-rank learning. Moreover, the low-dimensional representation of original data can be paired with some informative structure by imposing an appropriate constraint, e.g., Laplacian regularizer. Therefore, we propose a novel constrained LRR method. The objective function is formulated as a constrained nuclear norm minimization problem, which can be solved by the inexact augmented Lagrange multiplier algorithm. Extensive experiments on image classification, human pose estimation, and robust face recovery have confirmed the superiority of our method.

Accession Number: WOS:000415727200020

PubMed ID: 27849552

Author Identifiers:

ISSN: 2168-2267

eISSN: 2168-2275

Record 8 of 275

Title: Entangled-photons compressive ghost imaging based on spatial correlation of sensing matrix

Author(s): Liu, DW (Liu, Dawei); Li, LF (Li, Lifei); Geng, YX (Geng, Yixing); Kang, Y (Kang, Yan); Zhang, TY (Zhang, Tongyi); Zhao, W (Zhao, Wei); Dong, WB (Dong, Weibin); Shi, KL (Shi, Kunlin)

Source: OPTICAL ENGINEERING  Volume: 56  Issue: 12  Article Number: 123108  DOI: 10.1117/1.OE.56.12.123108  Published: DEC 2017  

Abstract: Using the entangled photons generated by the spontaneous parametric down conversion as a light source, we demonstrate the first quantum ghost imaging system with a modified compressive sensing technique based on the spatial correlation of sensing matrix (SCCS). The ghost image is achieved at 16.27% sampling ratio of raster scanning and 0.65 photons/pixel at each measurement on average. Our results show that image quality and photon-utilization efficiency are remarkably enhanced in comparison with the traditional compressive imaging technique, due to the sensing matrix and noise-free measurement vector rebuilt by SCCS technique. It suggests the great potential of SCCS technique applied in quantum imaging and other quantum optics fields, such as quantum charactering and quantum state tomography to use the information loaded in each photon with high efficiency. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

Accession Number: WOS:000419965800020

ISSN: 0091-3286

eISSN: 1560-2303

Record 9 of 275

Title: Generation of Circular Optical Vortex Array

Author(s): Ma, HX (Ma, Haixiang); Li, XZ (Li, Xinzhong); Tai, YP (Tai, Yuping); Li, HH (Li, Hehe); Wang, JG (Wang, Jingge); Tang, MM (Tang, Miaomiao); Tang, J (Tang, Jie); Wang, YS (Wang, Yishan); Nie, ZG (Nie, Zhaogang)

Source: ANNALEN DER PHYSIK  Volume: 529  Issue: 12  Article Number: 1700285  DOI: 10.1002/andp.201700285  Published: DEC 2017  

Abstract: We report on a novel optical vortex array named circular optical vortex array, which is generated by the superposition of two concentric perfect optical vortices. The circular optical vortex array has a constant topological charge of +1 or -1, the number and sign of which are determined by the topological charges of the two perfect optical vortices. Moreover, the radius of the circular optical vortex array is easily adjusted by using the cone angle of an axicon. Furthermore, the circular optical vortex array and multiple circular optical vortex array can be rotated by changing the initial phase difference of the perfect optical vortices on demand. This work demonstrates a complex structured optical field, which is of significance for applications such as optical tweezers, micro-particle manipulation, and optical imaging.

Accession Number: WOS:000417031900013

Author Identifiers:

ISSN: 0003-3804

eISSN: 1521-3889

Record 10 of 275

Title: Convex Multiview Semi-Supervised Classification

Author(s): Nie, FP (Nie, Feiping); Li, J (Li, Jing); Li, XL (Li, Xuelong)

Source: IEEE TRANSACTIONS ON IMAGE PROCESSING  Volume: 26  Issue: 12  Pages: 5718-5729  DOI: 10.1109/TIP.2017.2746270  Published: DEC 2017  

Abstract: In many practical applications, there are a great number of unlabeled samples available, while labeling them is a costly and tedious process. Therefore, how to utilize unlabeled samples to assist digging out potential information about the problem is very important. In this paper, we study a multiclass semi-supervised classification task in the context of multiview data. First, an optimization method named Parametric multiview semi-supervised classification (PMSSC) is proposed, where the built classifier for each individual view is explicitly combined with a weight factor. By analyzing the weakness of it, a new adapted weight learning strategy is further formulated, and we come to the convex multiview semi-supervised classification (CMSSC) method. Comparing with the PMSSC, this method has two significant properties. First, without too much loss in performance, the newly used weight learning technique achieves eliminating a hyperparameter, and thus it becomes more compact in form and practical to use. Second, as its name implies, the CMSSC models a convex problem, which avoids the local-minimum problem. Experimental results on several multiview data sets demonstrate that the proposed methods achieve better performances than recent representative methods and the CMSSC is preferred due to its good traits.

Accession Number: WOS:000412433000008

PubMed ID: 28866496

Author Identifiers:

ISSN: 1057-7149

eISSN: 1941-0042

Record 11 of 275

Title: Leveraging Spatial Context Disparity for Power Line Detection

Author(s): Pan, CF (Pan, Chaofeng); Shan, HT (Shan, Haotian); Cao, XB (Cao, Xianbin); Li, XL (Li, Xuelong); Wu, DP (Wu, Dapeng)

Source: COGNITIVE COMPUTATION  Volume: 9  Issue: 6  Pages: 766-779  DOI: 10.1007/s12559-017-9488-y  Published: DEC 2017  

Abstract: For the safety of low flying aircraft, it will become increasingly important that an aircraft should have the ability to detect and avoid small obstacles in the low flying environment. In recent years, using context information to assist in detecting power lines has shown great potential to better detect power lines at a remote distance. Therefore, how to adequately use the context information for a better detection is a hot issue of concern. This paper proposes a novel auxiliary assisted power line detection method, in which the spatial context disparity of auxiliaries is quantitatively and uniformly evaluated for the first time. As a cognitive strategy, the spatial context disparity depends on two factors, the spatial context peakedness and the spatial context difference. With this cognitive method, objects that achieve high spatial context disparity scores are more suitable for being the auxiliaries of the power lines. Experimental results show that, owing to the spatial context disparity, the proposed method can acquire proper auxiliaries with abundant context information to support the detection, so that better power line detections are achieved comparing to traditional power line detection methods. The proposed power line detection method, which can automatically choose the optimal auxiliaries, is effective and has the potential for practical use in ensuring the flight safety of unmanned air vehicles (UAVs) in the low flying environment.

Accession Number: WOS:000417682600004

Author Identifiers:

ISSN: 1866-9956

eISSN: 1866-9964

Record 12 of 275

Title: Cascade Learning by Optimally Partitioning

Author(s): Pang, YW (Pang, Yanwei); Cao, JL (Cao, Jiale); Li, XL (Li, Xuelong)

Source: IEEE TRANSACTIONS ON CYBERNETICS  Volume: 47  Issue: 12  Pages: 4148-4161  DOI: 10.1109/TCYB.2016.2601438  Published: DEC 2017  

Abstract: Cascaded AdaBoost classifier is a well-known efficient object detection algorithm. The cascade structure has many parameters to be determined. Most of existing cascade learning algorithms are designed by assigning detection rate and false positive rate to each stage either dynamically or statically. Their objective functions are not directly related to minimum computation cost. These algorithms are not guaranteed to have optimal solution in the sense of minimizing computation cost. On the assumption that a strong classifier is given, in this paper, we propose an optimal cascade learning algorithm (iCascade) which iteratively partitions the strong classifiers into two parts until predefined number of stages are generated. iCascade searches the optimal partition point r(i) of each stage by directly minimizing the computation cost of the cascade. Theorems are provided to guarantee the existence of the unique optimal solution. Theorems are also given for the proposed efficient algorithm of searching optimal parameters ri. Once a new stage is added, the parameter ri for each stage decreases gradually as iteration proceeds, which we call decreasing phenomenon. Moreover, with the goal of minimizing computation cost, we develop an effective algorithm for setting the optimal threshold of each stage. In addition, we prove in theory why more new weak classifiers in the current stage are required compared to that of the previous stage. Experimental results on face detection and pedestrian detection demonstrate the effectiveness and efficiency of the proposed algorithm.

Accession Number: WOS:000415727200012

PubMed ID: 28113530

Author Identifiers:

ISSN: 2168-2267

eISSN: 2168-2275

Record 13 of 275

Title: An Allotype Double H-V Depolarizer for Hyperfine Spectrometer

Author(s): Tang, Q (Tang Qian); Guo, LX (Guo Li-xin); Zhao, BC (Zhao Bao-chang)

Source: SPECTROSCOPY AND SPECTRAL ANALYSIS  Volume: 37  Issue: 12  Pages: 3913-3919  DOI: 10.3964/j.issn.1000-0593(2017)12-3913-07  Published: DEC 2017  

Abstract: High precision atmospheric detection spectrometers are widely used, because the sunlight would be polarized while passing the atmosphere and that could reduce detecting precision of the devices. There are many efforts on removing this influence. An allotype double H-V(Horizontal-Vertical) depolarizer is proposed, and it is equipped on hyperfine spectrometer used for atmosphere detecting in UV. Because the birefringence structure of crystals could eliminate the polarization, they are always chosen for depolarizers. Essentially, the birefringence of depolarizer can induce depolarization and double-imaging at the same time. The difference between traditional structure and the allotype is the inequality of the wedge angles of two sub H-Vs. There are different double-imaging distances in the spectrum dimension and the spatial dimension. So the contradiction between high depolarization and high-imaging quality could be resolved. This paper will describe the design and analyzed the result. Depolarization is better than 98.8% and distance of the double-imaging is just 8.7% in the spatial dimension.

Accession Number: WOS:000418728900047

Author Identifiers:

ISSN: 1000-0593

Record 14 of 275

Title: Single shot, three dimensional fluorescence microscopy with a spatially rotating point spread function

Author(s): Wang, ZJ (Wang, Zhaojun); Cai, YA (Cai, Yanan); Liang, YS (Liang, Yansheng); Zhou, X (Zhou, Xing); Yan, SH (Yan, Shaohui); Dan, D (Dan, Dan); Bianco, PR (Bianco, Piero R.); Lei, M (Lei, Ming); Yao, BL (Yao, Baoli)

Source: BIOMEDICAL OPTICS EXPRESS  Volume: 8  Issue: 12  Pages: 5493-5506  DOI: 10.1364/BOE.8.005493  Published: DEC 1 2017  

Abstract: A wide-field fluorescence microscope with a double-helix point spread function (PSF) is constructed to obtain the specimen's three-dimensional distribution with a single snapshot. Spiral-phase-based computer-generated holograms (CGHs) are adopted to make the depth-of-field of the microscope adjustable. The impact of system aberrations on the double-helix PSF at high numerical aperture is analyzed to reveal the necessity of the aberration correction. A modified cepstrum-based reconstruction scheme is promoted in accordance with properties of the new double-helix PSF. The extended depth-of-field images and the corresponding depth maps for both a simulated sample and a tilted section slice of bovine pulmonary artery endothelial (BPAE) cells are recovered, respectively, verifying that the depth-of-field is properly extended and the depth of the specimen can be estimated at a precision of 23.4mn. This three-dimensional fluorescence microscope with a framerate-rank time resolution is suitable for studying the fast developing process of thin and sparsely distributed micron-scale cells in extended depth-of-field. (C) 2017 Optical Society of America under the terms of the USA Open Access Publishing Agreement

Accession Number: WOS:000417583800012

PubMed ID: 29296483

Author Identifiers:

ISSN: 2156-7085

Record 15 of 275

Title: High power, high efficiency continuous-wave 808 nm laser diode arrays

Author(s): Wang, ZF (Wang, Zhenfu); Li, T (Li, Te); Yang, GW (Yang, Guowen); Song, YF (Song, Yunfei)

Source: OPTICS AND LASER TECHNOLOGY  Volume: 97  Pages: 297-301  DOI: 10.1016/j.optlastec.2017.07.015  Published: DEC 1 2017  

Abstract: The continuous-wave 100 W-class 808 nm laser diode arrays with extremely high power conversion efficiency of 68% were reported at the heatsink temperature of 25 degrees C. To the best of our knowledge, this was the highest power conversion efficiency at continuous-wave 106 W 808 nm laser diode array with 50% fill factor so far. An asymmetric broad waveguide epitaxial structure with very low internal optical loss of 0.5 cm(-1) was presented. In order to improve the efficiency, various fill factor devices were studied. The 50 W laser diode array with 30% fill factoir and 1.0 mm cavity length demonstrated power conversion efficiency of 71% at heatsink temperature of 15 degrees C. (C) 2017 Elsevier Ltd. All rights reserved.

Accession Number: WOS:000409284800039

Author Identifiers:

ISSN: 0030-3992

eISSN: 1879-2545

Record 16 of 275

Title: Influence of Layup and Curing on the Surface Accuracy in the Manufacturing of Carbon Fiber Reinforced Polymer (CFRP) Composite Space Mirrors

Author(s): Yang, ZY (Yang, Zhiyong); Zhang, JB (Zhang, Jianbao); Xie, YJ (Xie, Yongjie); Zhang, BM (Zhang, Boming); Sun, BG (Sun, Baogang); Guo, HJ (Guo, Hongjun)

Source: APPLIED COMPOSITE MATERIALS  Volume: 24  Issue: 6  Pages: 1447-1458  DOI: 10.1007/s10443-017-9595-7  Published: DEC 2017  

Abstract: Carbon fiber reinforced polymer, CFRP, composite materials have been used to fabricate space mirror. Usually the composite space mirror can completely replicate the high-precision surface of mould by replication process, but the actual surface accuracy of replicated space mirror is always reduced, still needed further study. We emphatically studied the error caused by layup and curing on the surface accuracy of space mirror through comparative experiments and analyses, the layup and curing influence factors include curing temperature, cooling rate of curing, method of prepreg lay-up, and area weight of fiber. Focusing on the four factors, we analyzed the error influence rule and put forward corresponding control measures to improve the surface figure of space mirror. For comparative analysis, six CFRP composite mirrors were fabricated and surface profile of mirrors were measured. Four guiding control measures were described here. Curing process of composite space mirror is our next focus.

Accession Number: WOS:000416529500011

Author Identifiers:

ISSN: 0929-189X

eISSN: 1573-4897

Record 17 of 275

Title: Data preprocessing methods for robust Fourier ptychographic microscopy

Author(s): Zhang, Y (Zhang, Yan); Pan, A (Pan, An); Lei, M (Lei, Ming); Yao, BL (Yao, Baoli)

Source: OPTICAL ENGINEERING  Volume: 56  Issue: 12  Article Number: 123107  DOI: 10.1117/1.OE.56.12.123107  Published: DEC 2017  

Abstract: Fourier ptychographic microscopy (FPM) is a recently developed computational imaging technique that achieves gigapixel images with both high resolution and large field-of-view. In the current FPM experimental setup, the dark-field images with high-angle illuminations are easily overwhelmed by stray lights and background noises due to the low signal-to-noise ratio, thus significantly degrading the achievable resolution of the FPM approach. We provide an overall and systematic data preprocessing scheme to enhance the FPM's performance, which involves sampling analysis, underexposed/overexposed treatments, background noises suppression, and stray lights elimination. It is demonstrated experimentally with both US Air Force (USAF) 1951 resolution target and biological samples that the benefit of the noise removal by these methods far outweighs the defect of the accompanying signal loss, as part of the lost signals can be compensated by the improved consistencies among the captured raw images. In addition, the reported nonparametric scheme could be further cooperated with the existing state-of-the-art algorithms with a great flexibility, facilitating a stronger noise-robust capability of the FPM approach in various applications. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

Accession Number: WOS:000419965800019

Author Identifiers:

ISSN: 0091-3286

eISSN: 1560-2303

Record 18 of 275

Title: When Collaboration Hugs Intelligence: Content Delivery over Ultra-Dense Networks

Author(s): Zhou, L (Zhou, Liang); Wu, D (Wu, Dan); Dong, ZJ (Dong, Zhenjiang); Li, XL (Li, Xuelong)

Source: IEEE COMMUNICATIONS MAGAZINE  Volume: 55  Issue: 12  Pages: 91-95  DOI: 10.1109/MCOM.2017.1700481  Published: DEC 2017  

Abstract: With the increasing popularity of traffic-intensive video applications, UDNs are treated as one of the most promising technologies for massive video delivery. However, due to the drastic interference between neighboring cells, how to achieve high energy and spectrum efficiency is still an open and challenging problem. This work proposes a systematic solution for content delivery over UDNs by integrating collaboration with intelligence. In particular, we first design a hybrid video coding scheme that is flexible and robust to the dynamic wireless environment. Then an active and proactive video update strategy is designed by intelligently alleviating the impact of the interference. Finally, a collaborative video scheduling scheme is developed to maximize the video quality as well as the energy and spectrum efficiency. Importantly, we summarize three fundamental design guidelines, and believe that they are useful for improving the transmission capacity of UDNs.

Accession Number: WOS:000418412800016

Author Identifiers:

ISSN: 0163-6804

eISSN: 1558-1896

Record 19 of 275

Title: Speckle-correlation imaging through scattering media with hybrid bispectrum-iteration algorithm

Author(s): Zhou, ML (Zhou, Meiling); Singh, AK (Singh, Alok Kumar); Pedrini, G (Pedrini, Giancarlo); Osten, W (Osten, Wolfgang); Min, JW (Min, Junwei); Yao, BL (Yao, Baoli)

Source: OPTICAL ENGINEERING  Volume: 56  Issue: 12  Article Number: 123102  DOI: 10.1117/1.OE.56.12.123102  Published: DEC 2017  

Abstract: We present an improved iteration algorithm for speckle-correlation imaging through scattering media. We employ an approximate solution obtained from a bispectrum-analysis method as the initial condition of the iterative process. This method avoids several different runs performed with different random initial conditions in the traditional iteration algorithm and reduces the execution time in comparison with the conventional bispectrum-analysis method. Therefore, we obtain a balance between image quality and reconstruction speed. The feasibility of the proposed method is proved by the experimental results. (c) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

Accession Number: WOS:000419965800014

Author Identifiers:

ISSN: 0091-3286

eISSN: 1560-2303

Record 20 of 275

Title: Temporal imaging based on four-wave mixing in slow-light photonic crystal waveguide

Author(s): Zhou, MY (Zhou, Mingyang); Liu, HJ (Liu, Hongjun); Wang, ZL (Wang, Zhaolu); Huang, N (Huang, Nan); Han, J (Han, Jing)

Source: JOURNAL OF OPTICS  Volume: 19  Issue: 12  Article Number: 125502  DOI: 10.1088/2040-8986/aa9138  Published: DEC 2017  

Abstract: We have proposed a temporal imaging system based on four-wave mixing (FWM) in the dispersion engineered slow-light photonic crystal waveguide (PCW). Dispersion relations of the modified PCW are calculated through the 3D plane wave expansion method. Time lens is demonstrated by solving the couple-mode equations describing the FWM process inside the PCW directly. Intensity and phase evolutions of the signal, pump and idler waves during the FWM process are calculated to investigate temporal imaging. Meanwhile, temporal magnifications with different magnification factors are realized by tuning the total dispersion of the input signals. Furthermore, influences of dispersion and free-carrier effects inside PCW on the temporal imaging performance are analyzed. The simulation results show the capability to realize temporal imaging system based on the FWM process in slow-light engineered PCW.

Accession Number: WOS:000425215900001

Author Identifiers:

ISSN: 2040-8978

eISSN: 2040-8986

Record 21 of 275

Title: MoS₂-wrapped microfiber-based multi-wavelength soliton fiber laser

Author(s): Lu, FF (Lu, Feifei)

Source: MODERN PHYSICS LETTERS B  Volume: 31  Issue: 32  Article Number: 1750303  DOI: 10.1142/S0217984917503031  Published: NOV 20 2017  

Abstract: The single-, dual- and triple-wavelength passively mode-locked erbium-doped fiber lasers are demonstrated with MoS2 and polarization-dependent isolator (PD-ISO). The saturable absorber is fabricated by wrapping an MoS2 around a microfiber. The intracavity PD-ISO acts as a wavelength-tunable filter with a polarization controller (PC) by adjusting the linear birefringence. Single-wavelength mode-locked fiber laser can self-start with suitable pump power. With appropriate PC state, dual- and triple-wavelength operations can be observed when gains at different wavelengths reach a balance. It is noteworthy that dual-wavelength pulses exhibiting peak and dip sidebands, respectively, are demonstrated in the experiment. The proposed simple and multi-wavelength all-fiber conventional soliton lasers could possess potential applications in numerous fields, such as sensors, THz generations and optical communications.

Accession Number: WOS:000415767000010

ISSN: 0217-9849

eISSN: 1793-6640

Record 22 of 275

Title: Wavelength-tunable passively mode-locked mid-infrared Er<SUP>3+</SUP>-doped ZBLAN fiber laser

Author(s): Shen, YL (Shen, Yanlong); Wang, YS (Wang, Yishan); Chen, HW (Chen, Hongwei); Luan, KP (Luan, Kunpeng); Tao, MM (Tao, Mengmeng); Si, JH (Si, Jinhai)

Source: SCIENTIFIC REPORTS  Volume: 7  Article Number: 14913  DOI: 10.1038/s41598-017-13089-6  Published: NOV 2 2017  

Abstract: A passively mode-locked Er3+-doped ZBLAN fiber laser around 3 mu m with a wide wavelength tuning range is proposed and demonstrated. The laser cavity was comprised of a semiconductor saturable absorber mirror and a blazed grating to provide a wavelength tunable feedback. The central wavelength of the mode-locked fiber laser can be continuously tuned from 2710 to 2820 nm. The pulse train had a maximum average power of higher than 203 mW, a repetition rate of 28.9 MHz and a pulse duration of 6.4 ps, yielding a peak power of exceeding 1.1 kW. To the best of our knowledge, this is the first demonstration of a wavelength-tunable passively mode-locked mid-infrared fiber laser at 3 mu m.

Accession Number: WOS:000414261500030

PubMed ID: 29097806

Author Identifiers:

ISSN: 2045-2322

Record 23 of 275

Title: Person Re-identification by Multi-hypergraph Fusion

Author(s): An, L (An, Le); Chen, XJ (Chen, Xiaojing); Yang, SF (Yang, Songfan); Li, XL (Li, Xuelong)

Source: IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS  Volume: 28  Issue: 11  Pages: 2763-2774  DOI: 10.1109/TNNLS.2016.2602082  Published: NOV 2017  

Abstract: Matching people across nonoverlapping cameras, also known as person re-identification, is an important and challenging research topic. Despite its great demand in many crucial applications such as surveillance, person re-identification is still far from being solved. Due to drastic view changes, even the same person may look quite dissimilar in different cameras. Illumination and pose variations further aggravate this discrepancy. To this end, various feature descriptors have been designed for improving the matching accuracy. Since different features encode information from different aspects, in this paper, we propose to effectively leverage multiple off-the-shelf features via multi-hypergraph fusion. A hypergraph captures not only pairwise but also high-order relationships among the subjects being matched. In addition, different from conventional approaches in which the matching is achieved by computing the pairwise distance or similarity between a probe and a gallery subject, the similarities between the probe and all gallery subjects are learned jointly via hypergraph optimization. Experiments on popular data sets demonstrate the effectiveness of the proposed method, and a superior performance is achieved as compared with the most recent state-of-the-arts.

Accession Number: WOS:000413403900025

PubMed ID: 28113383

Author Identifiers:

ISSN: 2162-237X

eISSN: 2162-2388

Record 24 of 275

Title: Chemical and spectroscopic investigations of K-H₃O-Na jarosite solid solutions applicable for Mars explorations

Author(s): Cao, FK (Cao, Fengke); Ling, ZC (Ling, Zongcheng); Ni, YH (Ni, Yuheng)

Source: JOURNAL OF RAMAN SPECTROSCOPY  Volume: 48  Issue: 11  Special Issue: SI  Pages: 1544-1553  DOI: 10.1002/jrs.5222  Published: NOV 2017  

Abstract: Jarosite is the first definitely discovered ferric sulfate mineral on Mars, indicating a highly acidic environment in Martian history. K-H3O and Na-H3O jarosite solid solutions were synthesized under hydrothermal conditions. Phase identifications and chemical compositions were determined by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy. Raman spectra of those two series of jarosite solid solutions show systematic spectral changes with varying alkali content. When chemical ratios of K/(K+H3O), in K-H3O jarosite solid solutions, increase from 0% to 88%, their Raman peaks exhibit systematic shifts: (2)(SO4)(2-) (from 424.7 to 434.3cm(-1)), (4)(SO4)(2-) (from 619.6 to 623.8cm(-1)), (1)(SO4)(2-) (from 1,011.8 to 1,006.1cm(-1)) and, (3)(SO4)(2-) (from 1,165.4 to 1,152.9cm(-1)). Near-infrared and mid-infrared spectra were also collected for the spectral library of Mars remote-sensing studies. The detailed chemical and spectroscopic studies of K-H3O-Na jarosite solid solutions would contribute to their potential discoveries on Mars by future Mars missions (e.g., Mars 2020 and ExoMars). Copyright (c) 2017 John Wiley & Sons, Ltd.

Accession Number: WOS:000416235800023

Author Identifiers:

ISSN: 0377-0486

eISSN: 1097-4555

Record 25 of 275

Title: Patch-based topic model for group detection

Author(s): Chen, ML (Chen, Mulin); Wang, Q (Wang, Qi); Li, XL (Li, Xuelong)

Source: SCIENCE CHINA-INFORMATION SCIENCES  Volume: 60  Issue: 11  Article Number: 113101  DOI: 10.1007/s11432-017-9237-1  Published: NOV 2017  

Abstract: Pedestrians in crowd scenes tend to connect with each other and form coherent groups. In order to investigate the collective behaviors in crowds, plenty of studies have been conducted on group detection. However, most of the existing methods are limited to discover the underlying semantic priors of individuals. By segmenting the crowd image into patches, this paper proposes the Patch-based Topic Model (PTM) for group detection. The main contributions of this study are threefold: (1) the crowd dynamics are represented by patch-level descriptor, which provides a macroscopic-level representation; (2) the semantic topic label of each patch are inferred by integrating the Latent Dirichlet Allocation (LDA) model and the Markov Random Fields (MRF); (3) the optimal group number is determined automatically with an intro-class distance evaluation criterion. Experimental results on real-world crowd videos demonstrate the superior performance of the proposed method over the state-of-the-arts.

Accession Number: WOS:000415021600009

Author Identifiers:

ISSN: 1674-733X

eISSN: 1869-1919

Record 26 of 275

Title: 844-fs mode-locked fiber laser by carboxyl-functionalized graphene oxide

Author(s): Duan, L (Duan, Lina); Wang, HS (Wang, Hushan); Bai, J (Bai, Jing); Wang, YG (Wang, Yonggang); Wei, LL (Wei, Lianglei); Chen, ZD (Chen, Zhendong); Yu, J (Yu, Jia); Wen, J (Wen, Jin); Li, Y (Li, Yan)

Source: OPTICAL ENGINEERING  Volume: 56  Issue: 11  Article Number: 116104  DOI: 10.1117/1.OE.56.11.116104  Published: NOV 2017  

Abstract: We had proved that a kind of graphene nanomaterial "carboxyl-functionalized graphene oxide (GO-COOH)" possessed nonlinear saturable absorber (SA) property. The modulation depth of a GO-COOH water solution was measured as similar to 8%. Moreover, a GO-COOH-based SA device was made and applied in an erbium-doped fiber laser. In this fiber laser, Q-switching pulses and mode-locked pulses were both obtained. With an increase in the pump power, the pulse width of Q-switching pulses decreased from 9.05 to 2.49 mu s. The mode-locked pulse width was 844 fs, and the corresponding spectral bandwidth was 3.64 nm. Moreover, polarization adjusting or control was not needed during the whole process of mode locking. It illustrated that the proposed fiber laser incorporating GO-COOH could endure bigger intracavity birefringence. Our results indicated that the GO-COOH nanomaterial was a promising SA for generating high-performance pulse lasers. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

Accession Number: WOS:000418064900049

Author Identifiers:

ISSN: 0091-3286

eISSN: 1560-2303

Record 27 of 275

Title: Graph Regularized Non-Negative Low-Rank Matrix Factorization for Image Clustering

Author(s): Li, XL (Li, Xuelong); Cui, GS (Cui, Guosheng); Dong, YS (Dong, Yongsheng)

Source: IEEE TRANSACTIONS ON CYBERNETICS  Volume: 47  Issue: 11  Pages: 3840-3853  DOI: 10.1109/TCYB.2016.2585355  Published: NOV 2017  

Abstract: Non-negative matrix factorization (NMF) has been one of the most popular methods for feature learning in the field of machine learning and computer vision. Most existing works directly apply NMF on high-dimensional image datasets for computing the effective representation of the raw images. However, in fact, the common essential information of a given class of images is hidden in their low rank parts. For obtaining an effective low-rank data representation, we in this paper propose a non-negative low-rank matrix factorization (NLMF) method for image clustering. For the purpose of improving its robustness for the data in a manifold structure, we further propose a graph regularized NLMF by incorporating the manifold structure information into our proposed objective function. Finally, we develop an efficient alternating iterative algorithm to learn the low-dimensional representation of low-rank parts of images for clustering. Alternatively, we also incorporate robust principal component analysis into our proposed scheme. Experimental results on four image datasets reveal that our proposed methods outperform four representative methods.

Accession Number: WOS:000413003100029

Author Identifiers:

ISSN: 2168-2267

eISSN: 2168-2275

Record 28 of 275

Title: Nuclear Norm-Based 2DLPP for Image Classification

Author(s): Lu, YW (Lu, Yuwu); Yuan, C (Yuan, Chun); Lai, ZH (Lai, Zhihui); Li, XL (Li, Xuelong); Wong, WK (Wong, Wai Keung); Zhang, D (Zhang, David)

Source: IEEE TRANSACTIONS ON MULTIMEDIA  Volume: 19  Issue: 11  Pages: 2391-2403  DOI: 10.1109/TMM.2017.2703130  Published: NOV 2017  

Abstract: Two-dimensional locality preserving projections (2DLPP) that use 2D image representation in preserving projection learning can preserve the intrinsic manifold structure and local information of data. However, 2DLPP is based on the Euclidean distance, which is sensitive to noise and outliers in data. In this paper, we propose a novel locality preserving projection method called nuclear norm-based two-dimensional locality preserving projections (NN-2DLPP). First, NN-2DLPP recovers the noisy data matrix through low-rank learning. Second, noise in data is removed and the learned clean data points are projected on a new subspace. Without the disturbance of noise, data points belonging to the same class are kept as close to each other as possible in the new projective subspace. Experimental results on six public image databases with face recognition, object classification, and handwritten digit recognition tasks demonstrated the effectiveness of the proposed method.

Accession Number: WOS:000413068200003

Author Identifiers:

ISSN: 1520-9210

eISSN: 1941-0077

Record 29 of 275

Title: A generalized power iteration method for solving quadratic problem on the Stiefel manifold

Author(s): Nie, FP (Nie, Feiping); Zhang, R (Zhang, Rui); Li, XL (Li, Xuelong)

Source: SCIENCE CHINA-INFORMATION SCIENCES  Volume: 60  Issue: 11  Article Number: 112101  DOI: 10.1007/s11432-016-9021-9  Published: NOV 2017  

Abstract: In this paper, we first propose a novel generalized power iteration (GPI) method to solve the quadratic problem on the Stiefel manifold (QPSM) as min(W)T(W)=(I) Tr(W(T)AW - 2W(T)B) along with the theoretical analysis. Accordingly, its special case known as the orthogonal least square regression (OLSR) is under further investigation. Based on the aforementioned studies, we then majorly focus on solving the unbalanced orthogonal procrustes problem (UOPP). As a result, not only a general convergent algorithm is derived theoretically but the efficiency of the proposed approach is verified empirically as well.

Accession Number: WOS:000417334600006

Author Identifiers:

ISSN: 1674-733X

eISSN: 1869-1919

Record 30 of 275

Title: Effects of doping SiO₂ on the defect's change in B₂O₃-containing phosphate based laser glasses used for high energy UV lasers

Author(s): Sun, MY (Sun, Mengya); Duan, ZJ (Duan, Zhanjun); Wang, PF (Wang, Pengfei); Lu, M (Lu, Min); Peng, B (Peng, Bo)

Source: OPTICAL MATERIALS EXPRESS  Volume: 7  Issue: 11  Pages: 4111-4122  DOI: 10.1364/OME.7.004111  Published: NOV 1 2017  

Abstract: The introduction of SiO2 affects the glass's micro-structure and micro-defects as well as the corresponding optical and physical properties of the B2O3-containing multicomponent phosphate glasses. The addition of SiO2 increases the transition temperature and causes shifts of the UV cut-off wavelength (lambda(cut-off)). The changes of lambda(cut-off) are closely related to the PO3-EC and PO4-EC defect centers that are associated with the Q(2) tetrahedral in phosphate chains. The corresponding variations of Q(2) units can also be found in the Raman, XPS, and P-31 MAS-NMR spectra. With increasing the content of SiO2, the ratio of nonbridging oxygen (associated with Q(2) units) is gradually decreased down to a critical level when SiO2/B2O3 ratio is 4/1.5, whereas the ratio of non-bridging oxygen increases when SiO2/B2O3 ratio is larger than 4/1.5, which suggests that the doping SiO2 can influence the concentration of PO3-EC and PO4-EC defects. Those results can be better obtained when the sample is exposed to gamma irradiation. As the SiO2 content increased gradually up to 4/1.5, the concentration of the PO3-EC defects declined, while the concentration of PO4-EC and the POHC defects increased when considering the irradiation dose, indicating that the addition of SiO2 can regulate the structure-related defects in phosphate based glasses. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Accession Number: WOS:000414248700030

Author Identifiers:

ISSN: 2159-3930

Record 31 of 275

Title: Roles of palladium particles in enhancing the electrochemical migration resistance of sintered nano-silver paste as a bonding material

Author(s): Wang, D (Wang, Di); Mei, YH (Mei, Yun-Hui); Xie, HN (Xie, Haining); Zhang, K (Zhang, Kun); Siow, KS (Siow, Kim S.); Li, X (Li, Xin); Lu, GQ (Lu, Guo-Quan)

Source: MATERIALS LETTERS  Volume: 206  Pages: 1-4  DOI: 10.1016/j.matlet.2017.06.066  Published: NOV 1 2017  

Abstract: The inhibition effect and mechanism of adding palladium particles to nano-silver paste on the migration of silver in high temperature is reported. The electrochemical migration (ECM) tests showed that silver migration was significantly delayed by the addition of palladium. The roles of different compositions, e.g., PdO, in enhancing the ECM resistance of silver were studied experimentally. We found Ag-Pd alloy < PdO < PdO (the oxidation process of palladium). The oxidation of palladium to palladium (II) oxides (PdO) suppressed the silver oxides to delay the onset of silver dendrites formation resulting in longer failure lifetime than the pure PdO, Ag-Pd alloy or a simple combination of the two. (C) 2017 Elsevier B.V. All rights reserved.

Accession Number: WOS:000407407300001

Author Identifiers:

ISSN: 0167-577X

eISSN: 1873-4979

Record 32 of 275

Title: Wavelength-switchable passively mode-locked fiber laser with mechanically exfoliated molybdenum ditelluride on side-polished fiber

Author(s): Wang, GM (Wang, Guomei)

Source: OPTICS AND LASER TECHNOLOGY  Volume: 96  Pages: 307-312  DOI: 10.1016/j.optlastec.2017.05.030  Published: NOV 1 2017  

Abstract: We experimentally investigated the nonlinear saturable absorption characteristics of molybdenum ditelluride (MoTe2) and demonstrated a wavelength-switchable mode-locked erbium-doped fiber laser (EDFL) by using MoTe2 thin film on side-polished fiber (SPF) as saturable absorber. Here, the MoTe2 thin film was efficiently fabricated via mechanical exfoliation method and transferred onto the SPF with the assistance of polydimethylsiloxane (PDMS). MoTe2-covered SPF (MSPF) exhibits the nonlinear saturable absorption for pulses with different polarization states. Optical solitons with spectral bandwidth of 1.06 (1.31) nm centered at similar to 1559 (similar to 1528) nm and pulse duration of 2.46 (2.04) ps can be obtained from the EDFL by adjusting the polarization controller (PC) properly. The time-bandwidth product (TBP) of the pulses was calculated as 0.322 (0.344). (C) 2017 Elsevier Ltd. All rights reserved.

Accession Number: WOS:000405051800043

ISSN: 0030-3992

eISSN: 1879-2545

Record 33 of 275

Title: Locality Adaptive Discriminant Analysis for Spectral-Spatial Classification of Hyperspectral Images

Author(s): Wang, Q (Wang, Qi); Meng, ZT (Meng, Zhaotie); Li, XL (Li, Xuelong)

Source: IEEE GEOSCIENCE AND REMOTE SENSING LETTERS  Volume: 14  Issue: 11  Pages: 2077-2081  DOI: 10.1109/LGRS.2017.2751559  Published: NOV 2017  

Abstract: Linear discriminant analysis (LDA) is a popular technique for supervised dimensionality reduction, but with less concern about a local data structure. This makes LDA inapplicable to many real-world situations, such as hyperspectral image (HSI) classification. In this letter, we propose a novel dimensionality reduction algorithm, locality adaptive discriminant analysis (LADA) for HSI classification. The proposed algorithm aims to learn a representative subspace of data, and focuses on the data points with close relationship in spectral and spatial domains. An intuitive motivation is that data points of the same class have similar spectral feature and the data points among spatial neighborhood are usually associated with the same class. Compared with traditional LDA and its variants, LADA is able to adaptively exploit the local manifold structure of data. Experiments carried out on several real hyperspectral data sets demonstrate the effectiveness of the proposed method.

Accession Number: WOS:000413955500040

Author Identifiers:

ISSN: 1545-598X

eISSN: 1558-0571

Record 34 of 275

Title: Statistical Hypothesis Detector for Abnormal Event Detection in Crowded Scenes

Author(s): Yuan, Y (Yuan, Yuan); Feng, YC (Feng, Yachuang); Lu, XQ (Lu, Xiaoqiang)

Source: IEEE TRANSACTIONS ON CYBERNETICS  Volume: 47  Issue: 11  Pages: 3597-3608  DOI: 10.1109/TCYB.2016.2572609  Published: NOV 2017  

Abstract: Abnormal event detection is now a challenging task, especially for crowded scenes. Many existing methods learn a normal event model in the training phase, and events which cannot be well represented are treated as abnormalities. However, they fail to make use of abnormal event patterns, which are elements to comprise abnormal events. Moreover, normal patterns in testing videos may be divergent from training ones, due to the existence of abnormalities. To address these problems, in this paper, an abnormality detector is proposed to detect abnormal events based on a statistical hypothesis test. The proposed detector treats each sample as a combination of a set of event patterns. Due to the unavailability of labeled abnormalities for training, abnormal patterns are adaptively extracted from incoming unlabeled testing samples. Contributions of this paper are listed as follows: 1) we introduce the idea of a statistical hypothesis test into the framework of abnormality detection, and abnormal events are identified as ones containing abnormal event patterns while possessing high abnormality detector scores; 2) due to the complexity of video events, noise seldom follows a simple distribution. For this reason, we approximate the complex noise distribution by employing a mixture of Gaussian. This benefits the modeling of video events and improves abnormality detection accuracies; and 3) because of the existence of abnormalities, there are always some unusually occurring normal events in the testing videos, which differ from the training ones. To represent normal events precisely, an online updating strategy is proposed to cover these cases in the normal event patterns. As a result, false detections are eliminated mostly. Extensive experiments and comparisons with state-of-the-art methods verify the effectiveness of the proposed algorithm.

Accession Number: WOS:000413003100010

PubMed ID: 27323389

Author Identifiers:

ISSN: 2168-2267

eISSN: 2168-2275

Record 35 of 275

Title: Regularized Class-Specific Subspace Classifier

Author(s): Zhang, R (Zhang, Rui); Nie, FP (Nie, Feiping); Li, XL (Li, Xuelong)

Source: IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS  Volume: 28  Issue: 11  Pages: 2738-2747  DOI: 10.1109/TNNLS.2016.2598744  Published: NOV 2017  

Abstract: In this paper, we mainly focus on how to achieve the translated subspace representation for each class, which could simultaneously indicate the distribution of the associated class and the differences from its complementary classes. By virtue of the reconstruction problem, the class-specific subspace classifier (CSSC) problem could be represented as a series of biobjective optimization problems, which minimize and maximize the reconstruction errors of the related class and its complementary classes, respectively. Besides, the regularization term is specifically introduced to ensure the whole system's stability. Accordingly, a regularized class-specific subspace classifier (RCSSC) method can be further proposed based on solving a general quadratic ratio problem. The proposed RCSSC method consistently converges to the global optimal subspace and translation under the variations of the regularization parameter. Furthermore, the proposed RCSSC method could be extended to the unregularized case, which is known as unregularized CSSC (UCSSC) method via orthogonal decomposition technique. As a result, the effectiveness and the superiority of both proposed RCSSC and UCSSC methods can be verified analytically and experimentally.

Accession Number: WOS:000413403900023

PubMed ID: 28113607

Author Identifiers:

ISSN: 2162-237X

eISSN: 2162-2388

Record 36 of 275

Title: Multichannel phase-sensitive amplification in a low-loss CMOS-compatible spiral waveguide

Author(s): Zhang, YB (Zhang, Yanbing); Reimer, C (Reimer, Christian); Wu, J (Wu, Jenny); Roztocki, P (Roztocki, Piotr); Wetzel, B (Wetzel, Benjamin); Little, BE (Little, Brent E.); Chu, ST (Chu, Sai T.); Moss, DJ (Moss, David J.); Eggleton, BJ (Eggleton, Benjamin J.); Kues, M (Kues, Michael); Morandotti, R (Morandotti, Roberto)

Source: OPTICS LETTERS  Volume: 42  Issue: 21  Pages: 4391-4394  DOI: 10.1364/OL.42.004391  Published: NOV 1 2017  

Abstract: We investigate single-channel and multichannel phase-sensitive amplification (PSA) in a highly nonlinear, CMOS-compatible spiral waveguide with ultralow linear and negligible nonlinear losses. We achieve a net gain of 10.4 dB and an extinction ratio of 24.6 dB for single-channel operation, as well as a 5 dB gain and a 15 dB extinction ratio spanning over a bandwidth of 24 nm for multiple-channel operation. In addition, we derive a simple analytic solution that enables calculating the maximum phase-sensitive gain in any Kerr medium featuring linear and nonlinear losses. These results not only give a clear guideline for designing PSA-based amplifiers but also show that it is possible to implement both optical regeneration and amplification in a single on-chip device. (C) 2017 Optical Society of America

Accession Number: WOS:000414097200039

PubMed ID: 29088171

Author Identifiers:

ISSN: 0146-9592

eISSN: 1539-4794

Record 37 of 275

Title: Effect of substrate temperature and sputtering pressure on the microstructure and photoluminescence performance of ZnO films by magnetron sputtering

Author(s): Zhu, GF (Zhu, Guanfang); Gao, PP (Gao, Pengpeng); Kang, YF (Kang, Yifan); Jing, L (Jing, Liu); Yao, HB (Yao, Hebao); Wang, C (Wang, Chao)

Source: OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS  Volume: 11  Issue: 11-12  Pages: 709-715  Published: NOV-DEC 2017  

Abstract: The strong ultraviolet stimulated emission and the weak deep energy level emission was obtained at room temperature. The mechanisms of sputtering pressure impact on growth of ZnO films was also discussed. The low energy tail emission of ultraviolet photoluminescence was caused by the emission of bound exciton. The effect of sputtering pressure on the growth of films were observed. The structural property and photoluminescence performance were studied at different pressures. ZnO films by magnetron sputtering on glass substrates were fabricated with XRD FWHM of only 0.12 degrees exhibiting preferred orientation along c-axis growth at the proper substrate temperature and sputtering pressure.

Accession Number: WOS:000423092900020

Author Identifiers:

ISSN: 1842-6573

eISSN: 2065-3824

Record 38 of 275

Title: Sheared-beam imaging of object with depth information

Author(s): Lan, FY (Lan Fu-Yang); Luo, XJ (Luo Xiu-Juan); Chen, ML (Chen Ming-Lai); Zhang, Y (Zhang Yu); Liu, H (Liu Hui)

Source: ACTA PHYSICA SINICA  Volume: 66  Issue: 20  Article Number: 204202  DOI: 10.7498/aps.66.204202  Published: OCT 20 2017  

Abstract: Sheared-beam imaging technique is a non-conventional imaging method which can be used to image remote objects through atmospheric turbulence without needing any adaptive optics. In this imaging technique, the target is coherently illuminated by three laser beams which are laterally sheared at the transmitter plane and arranged into an L shape. In addition, each beam is modulated by a slight frequency shift. The speckle intensity signals scattered from the target are received by a detector array, and then the image of target can be reconstructed by computer algorithm. By far, most of studies in this field have focused on two-dimensional imaging. In real conditions, however, the surface of targets we are concerned about reveals that different depths introduce various phase delays in the scattering signal from target. This delay causes the phase-shift errors to appear between the ideal target Fourier spectrum and the Fourier spectrum received by detector array. Finally, this would result in poor image quality and low resolution. In this study, a three-dimensional target imaging model is established based on the two-dimensional target imaging model. The influence of modulated beat frequency between sheared beam and reference beam is studied on the objects with depth information, and the result shows that large beat frequency may have an adverse effect on reconstructed images. The simulation we have developed for this three-dimensional imaging model uses three targets with different shapes. Each target is divided into several sub-blocks, and we set different depth values (within 10 m) for these blocks. Then beat frequencies are increased from 5 Hz to about 1 MHz, respectively. At each pair of frequencies, the reconstructed image is recorded. Strehl ratio is used as the measure of the imaging quality. Computer simulation results show that the Strehl ratio of reconstructed images descends with the increase of beat frequency, which is fully consistent with the theory of three-dimensional target imaging proposed before. Meanwhile, we find that the depth distribution of target also has an effect on imaging quality. As for actual space targets, the maximum depth is usually not more than 10 m. Compared with the influence caused by beat frequencies, the effect produced by depth distribution is negligible. Therefore when a space target is imaged, beat frequencies play the major role in reconstructing high-quality image. The results presented in this paper indicate that in order to achieve better imaging quality in the practical application, it is necessary to select the smallest beat frequency according to the detector performance and keep the candidate frequencies away from the low-frequency noise of the detector.

Accession Number: WOS:000417417200009

ISSN: 1000-3290

Record 39 of 275

Title: Frequency-degenerate parametric generation through IFWM effect in nanowaveguides

Author(s): Liu, ML (Liu, Mulong); Wang, LR (Wang, Leiran); Sun, QB (Sun, Qibing); Wang, WQ (Wang, Weiqiang); Wang, GX (Wang, Guoxi); Li, SQ (Li, Siqi); Zhang, LX (Zhang, Lingxuan); Zhang, WF (Zhang, Wenfu); Hu, XH (Hu, Xiaohong); Gong, YK (Gong, Yongkang); Zhao, W (Zhao, Wei)

Source: MODERN PHYSICS LETTERS B  Volume: 31  Issue: 29  Article Number: 1750266  DOI: 10.1142/S0217984917502669  Published: OCT 20 2017  

Abstract: We investigate highly efficient frequency-degenerate parametric generation through inverse four-wave-mixing (IFWM) in silicon nanowaveguides, which exhibits distinctly from traditional FWM phenomenon and manifests itself as a unique process producing signal and idler photon pairs with frequencies at the center of two pumps. The influences of dispersion, nonlinear coefficient and frequency detuning on the IFWM process are numerically analyzed in detail. On this basis, the optimal condition for high gain IFWM and the nanowaveguide with high nonlinearity and large normal dispersion are proposed. These results substantiate the feasibility of such frequency-degenerate parametric generation in CMOS-compatible integrated platforms, which could find important potential in signal-processing systems for photonics networks and entangled qubits generation for quantum optics.

Accession Number: WOS:000413152400005

Author Identifiers:

ISSN: 0217-9849

eISSN: 1793-6640

Record 40 of 275

Title: Temperature-calibrated high-precision refractometer using a tilted fiber Bragg grating

Author(s): Jiang, BQ (Jiang, Biqiang); Zhou, KM (Zhou, Kaiming); Wang, CL (Wang, Changle); Zhao, YH (Zhao, Yunhe); Zhao, JL (Zhao, Jianlin); Zhang, L (Zhang, Lin)

Source: OPTICS EXPRESS  Volume: 25  Issue: 21  Pages: 25910-25918  DOI: 10.1364/OE.25.025910  Published: OCT 16 2017  

Abstract: We present a refractometer with main-and vernier-scale to measure the refractive index (RI) of liquids with high precision by using the fine spectrum structure of a tilted fiber Bragg grating (TFBG). The absolute RI values are determined by the accurate wavelength of cut-off mode resonances. The main-and vernier-scale are calibrated by measuring large groups of fine spectra at different cut-off mode resonances in a small RI range, and the use of vernier-scale certainly reduces the RI measurement uncertainty resulted from the discrete cladding mode resonances. The performance of the TFBG-based vernier refractometer is experimentally verified by exploring the temperature dependence of RI of anhydrous ethanol in a near infrared region, showing an enhanced accuracy to the order of 10(-4), high repeatability and temperature self-calibration capability. (c) 2017 Optical Society of America

Accession Number: WOS:000413103300096

PubMed ID: 29041253

Author Identifiers:

ISSN: 1094-4087

Record 41 of 275

Title: Eight-wave mixing parametrical amplification

Author(s): Liu, Y (Liu, Yang); Li, KK (Li, Kangkang); Liu, YZ (Liu, Yize); Yang, GG (Yang, Gaoguo); Wang, K (Wang, Kun); Zhang, YP (Zhang, Yanpeng)

Source: OPTICS EXPRESS  Volume: 25  Issue: 21  Pages: 25212-25221  DOI: 10.1364/OE.25.025212  Published: OCT 16 2017  

Abstract: We investigate parametrically amplified eight-wave mixing (PA-EWM). The double dressed PA-four-wave mixing (PA-FWM) is the superposition of one PA-FWM process, two different PA-six-wave mixing (PA-SWM) processes (PA-SWM1 and PA-SWM2 with external dressing field 776nm and 795nm, respectively) and one PA-EWM process. When the phases among FWM, SWM1, SWM2 and EWM change from 0 to pi, the double dressed PA-FWM could gradually satisfy the pure enhancement (all 0), partial enhancement and suppression (mixture of 0 and pi), or pure suppression condition (all pi). The outcomes of the investigation can potentially contribute to the development of multi-channel quantum information processing and high dimensional stereoscopic imaging. (C) 2017 Optical Society of America

Accession Number: WOS:000413103300034

PubMed ID: 29041191

Author Identifiers:

ISSN: 1094-4087

Record 42 of 275

Title: Graphene oxide-COOH as a new saturable absorber for both Q-switching and mode-locking fiber lasers

Author(s): Zhao, FY (Zhao, Fengyan); Wang, YS (Wang, Yishan); Wang, YG (Wang, Yonggang); Wang, HS (Wang, Hushan); Cai, YJ (Cai, Yajun)

Source: CHINESE OPTICS LETTERS  Volume: 15  Issue: 10  Article Number: 101402  DOI: 10.3788/COL201715.101402  Published: OCT 10 2017  

Abstract: Graphene oxide carboxylic acid (COOH), a novel two-dimensional (2D) layered material with its unique optical and electronic properties, is discovered to exhibit the saturation of optical absorption under laser illumination. Applying the liquid-phase exfoliation method, we prepare graphene oxide-COOH dispersions with deionized water and fabricate graphene oxide-COOH polyvinyl alcohol polymer composite film. We further obtain stable Q-switching pulse and mode-locked laser operation with a 22.7MHz repetition rate and a 1.5 ps pulse duration by incorporating the graphene oxide-COOH-based saturable absorbers into the all-fiber erbium-doped fiber laser cavity. The experimental results show that the proposed graphene oxide-COOH material can act as an effective absorber for pulsed fiber lasers, which demonstrate potential applications in the area of ultrafast optics.

Accession Number: WOS:000412692400017

Author Identifiers:

ISSN: 1671-7694

Record 43 of 275

Title: Method of controlling optical surface roughness based on stray light requirements

Author(s): Song, YS (Song Yan-Song); Yang, JF (Yang Jian-Feng); Li, F (Li Fu); Ma, XL (Ma Xiao-Long); Wang, H (Wang Hong)

Source: ACTA PHYSICA SINICA  Volume: 66  Issue: 19  Article Number: 194201  DOI: 10.7498/aps.66.194201  Published: OCT 5 2017  

Abstract: Scattering introduced by optical surface fabrication errors could degrade optical performance severely. Therefore, the optical designers are required to provide a roughness index for describing the specific surface or even all surfaces to ensure the final imaging performance. The surface root-mean-square (RMS) roughness is a common index to quantify surface topography. And there are also some available methods to acquire the surface RMS roughness based on bidirectional scattering distribution function theory or the angle spread function theory. However, the influence of the optical surface scattering on the optical system cannot be accurately revealed by the surface RMS roughness determined by these methods. On the one hand, the RMS roughness corresponds to an excessively wide spatial frequency range from 0 to 1/lambda, where lambda is the wavelength of the light. Consequently, it is difficult to measure the RMS roughness during manufacture. On the other hand, what really worsens the stray light performance of the system is only the surface profile located within a certain subinterval of the aforementioned frequency range, to put it in another way, the surface RMS roughness identified by the methods above is incompetent to quantify the amount of the energy that is surfacescattered to the detector. To address the issues above, in this paper we propose a novel approach to identifying the surface roughness. This method seeks to deduce the relation between optical surface RMS roughness and the stray light requirement of the system by dint of partial integrated scattering (PIS). In contrast to total integrated scattering, PIS counts the scattering light energy that could reach the detector. Hence, the RMS roughness identified in this way corresponds to the effective spatial frequency range that contributes to the stray light in the system. Firstly, the effective frequency range concerned with the system stray light level is identified through the analysis of the propagation path of the scattered light. Then, the surface RMS roughness would be measured within the established range according to the stray light requirement of the system and used to control the surface roughness as the roughness index during the optical manufacture process. The method not only considers the scattering as the surface characteristic, but also takes into account the influence of scattering on the system. Taking the solar magnetic field telescope (MFT) for example, the validity of the method is verified by comparing with the traditional methods. As manifested in the outcome, the effective frequency range of primary mirror is from 0 to 18 mm(-1), and the surface RMS roughness identified in such a new way can stage the stray light performance of MFT in a more precise manner, which is more reliable to serve as a surface roughness index.

Accession Number: WOS:000419013400009

Author Identifiers:

ISSN: 1000-3290

Record 44 of 275

Title: Remote Sensing Image Scene Classification: Benchmark and State of the Art

Author(s): Cheng, G (Cheng, Gong); Han, JW (Han, Junwei); Lu, XQ (Lu, Xiaoqiang)

Source: PROCEEDINGS OF THE IEEE  Volume: 105  Issue: 10  Special Issue: SI  Pages: 1865-1883  DOI: 10.1109/JPROC.2017.2675998  Published: OCT 2017  

Abstract: Remote sensing image scene classification plays an important role in a wide range of applications and hence has been receiving remarkable attention. During the past years, significant efforts have been made to develop various data sets or present a variety of approaches for scene classification from remote sensing images. However, a systematic review of the literature concerning data sets and methods for scene classification is still lacking. In addition, almost all existing data sets have a number of limitations, including the small scale of scene classes and the image numbers, the lack of image variations and diversity, and the saturation of accuracy. These limitations severely limit the development of new approaches especially deep learning-based methods. This paper first provides a comprehensive review of the recent progress. Then, we propose a large-scale data set, termed "NWPU-RESISC45," which is a publicly available benchmark for REmote Sensing Image Scene Classification (RESISC), created by Northwestern Polytechnical University (NWPU). This data set contains 31 500 images, covering 45 scene classes with 700 images in each class. The proposed NWPU-RESISC45 1) is large-scale on the scene classes and the total image number; 2) holds big variations in translation, spatial resolution, viewpoint, object pose, illumination, background, and occlusion; and 3) has high within-class diversity and between-class similarity. The creation of this data set will enable the community to develop and evaluate various data-driven algorithms. Finally, several representative methods are evaluated using the proposed data set, and the results are reported as a useful baseline for future research.

Accession Number: WOS:000411273300004

Author Identifiers:

ISSN: 0018-9219

eISSN: 1558-2256

Record 45 of 275

Title: Structural evolution study of additions of Sb₂S₃ and CdS into GeS₂ chalcogenide glass by Raman spectroscopy

Author(s): Guo, HT (Guo, Hai-Tao); Zhang, MJ (Zhang, Ming-Jie); Xu, YT (Xu, Yan-Tao); Xiao, XS (Xiao, Xu-Sheng); Yang, ZY (Yang, Zhi-Yong)

Source: CHINESE PHYSICS B  Volume: 26  Issue: 10  Article Number: 104208  DOI: 10.1088/1674-1056/26/10/104208  Published: OCT 2017