2017
2017
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Record 169 of
Title:Speckle-correlation imaging through scattering media with hybrid bispectrum-iteration algorithm
Author(s):Zhou, Meiling(1,2,3); Singh, Alok Kumar(1); Pedrini, Giancarlo(1); Osten, Wolfgang(1); Min, Junwei(2); Yao, Baoli(2)Source: Optical Engineering Volume: 56 Issue: 12 DOI: 10.1117/1.OE.56.12.123102 Published: December 1, 2017Abstract: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. ? 2017 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20181004853707 -
Record 170 of
Title:Penalized Linear Discriminant Analysis of Hyperspectral Imagery for Noise Removal
Author(s):Lu, Ming(1,2,3); Hu, Luojia(3); Yue, Tianxiang(1); Chen, Ziyue(3); Chen, Bin(3); Lu, Xiaoqiang(4); Xu, Bing(3,5)Source: IEEE Geoscience and Remote Sensing Letters Volume: 14 Issue: 3 DOI: 10.1109/LGRS.2016.2643001 Published: March 2017Abstract:The existence of noise in hyperspectral ima-gery (HSI) seriously affects image quality. Noise removal is one of the most important and challenging tasks to complete before hyperspectral information extraction. Though many advances have been made in alleviating the effect of noise, problems, including a high correlation among bands and predefined structure of noise covariance, still prevent us from the effective implementation of hyperspectral denoising. In this letter, a new algorithm named the penalized linear discriminant analysis (PLDA) and noise adjusted principal components transformation (NAPCT) was proposed. PLDA was applied to search for the best noise covariance structure, while the NAPCT was employed to remove the noise. The results of the tests with both HJ-1A HSI and EO-1 Hyperion showed that the proposed PLDA-NAPCT method could remove the noise effectively and that it could preserve the spectral fidelity of the restored hyperspectral images. Specifically, the recovered spectral curves using the proposed method are visually more similar to the original image compared with the control methods; quantitative matrices, including the noise reduction ration and mean relative deviation, also showed that the PLDA-NAPCT produced less bias than the control methods. Furthermore, the PLDA-NAPCT method is sensor-independent, and it could be easily adapted for removing the noise from different sensors. ? 2017 IEEE.Accession Number: 20170403275293 -
Record 171 of
Title:Small-size streak tube for imaging lidar
Author(s):Tian, Jinshou(1); Hui, Dandan(1,2); Luo, Duan(1,2); Wang, Tao(1); Zhang, Jun(3); Chen, Shaorong(3); Jia, Hui(3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10328 Issue: DOI: 10.1117/12.2269063 Published: 2017Abstract:Streak tube imaging lidar, as a novel flash lidar, due to its advantages of higher resolution for low contrast conditions, compact and rugged physical configurations, small image distortions owing to its scannerless design, and higher image update rates, has immense potential to provide 3D single-laser-pulse scannerless imaging, 3D multispectral imaging, 3D multispectral fluorescence imaging, and 3D polarimetry. In order to further reduce the size and enlarge the field of view (FOV) of the lidar system, we designed a super small-size, large photocathode area and meshless streak tube with spherical cathode and screen. With the aid of Computer Simulation Technology Software package (CST), a model of the streak tube was built, and its predominant performances were illustrated via tracking electron trajectories. Spatial resolution of the streak tube reaches 20lp/mm over the entire 028mm photocathode working area, and its temporal resolution is better than 30ps. Most importantly, the external dimensions of the streak tube are only 050mmx100mm. And several prototypes are already manufactured on the basis of the computer design. ? 2017 SPIE.Accession Number: 20171403517382 -
Record 172 of
Title:An estimated method of visibility for a remote sensing system based on LabVIEW and Arduino
Author(s):Chen, Xiaochuan(1,3); Ruan, Chi(2); Zheng, Hairong(3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10256 Issue: DOI: 10.1117/12.2258723 Published: 2017Abstract:Visibility data have long needed to traffic meteorological monitoring and warning system, but visibility data have monitored with expensive special equipment. Visibility degradation in fog is due to the light scattering of fog droplets, which are transit from aerosols via activation. Considering strong correlation between PM2.5 (Particulate matter with diameters less than 2.5μm) mass concentration and visibility, regression models can be useful tools for retrieving visibility data from available PM2.5 data. In this study, PM2.5 is measured by low cost and commercial equipment. The results of experiment indicate that relative humidity is the key factor to impact accuracy correlation between PM2.5 and visibility, the strongest correlation locates in the RH (2.5 mass concentration; however, it has been found the decrease rate tapers off gradually. In order to capture the real-time visibility data, to grasp the process of low visibility events, the design of remote monitoring system is put forward. Using the GPRS network to link to cloud as a server, proposed the Arduino as the controller, design and implements a wireless serial acquisition and control system based LabVIEW and Arduino, this system can achieve the function of real-time synchronization Web publishing. The result of the test indicates that this system has typical characteristics of friendly interface, high levels of reliability and expansibility, moreover it can retrieve visibility data from available PM2.5 data that can easy to access by low-cost sensor along the highway. ? 2017 SPIE.Accession Number: 20171703607577 -
Record 173 of
Title:Recent progress of high-coherence ultrafast electron sources
Author(s):Luo, Duan(1,2,3); Hui, Dan-Dan(1,2,3); Wen, Wen-Long(1); Liu, Rong(4); Wang, Xing(1); Tian, Jin-Shou(1,3)Source: Wuli Xuebao/Acta Physica Sinica Volume: 66 Issue: 15 DOI: 10.7498/aps.66.152901 Published: August 5, 2017Abstract:Microscopic dynamic process of material structure which determines the inherent property of substance takes place on a molecular and atomic scale. Understanding the underlying mechanisms of the various fundamental processes has always been the goal of chemistry, physics, biology and materials science. With Ahmed Zewail's pioneering work in the field of femtoscience, the time-resolved electron diffraction, combining the pump-probe and electron diffraction technique, has become an excellent tool with sufficient temporal precision to directly deliver insights into ultrafast phenomena on an atomic level. Central to this method is the ultrashort electron pulses generated from a metal photocathode. However, up to now, owing to the initial size, effective temperature, energy dispersion and inherent coulomb repulsion of electron source, the state-of-the-art transverse coherence of conventional planar cathode photoemission source is still insufficient to resolve the complex chemical and biological organic molecules. Hence, in recent years, many efforts have focused on developing high-coherence ultrashort electron sources. The main methods include minimizing the initial beam size, weakening the space charge, reducing the effective temperature, and matching the photon energy of laser with the work function of cathode material. In this review, we firstly summarize the history and advantages of the electron probe, secondly sketch out the figure of merit of the electron source. And then taking coherence as the main line, we review recent progress in common planar photoemission sources, and discuss the latest development of tip-based electron sources and cold atom electron sources in terms of their generation mechanisms, unique properties and research progress. Finally, the development and future applications of the diffraction technique are prospected. In general, the high-coherence length of photoelectric surface source is often at the expense of the current. The needle source can obtain the highest coherence length, but it is similar to femtosecond single-electron pulse, which must be less than one electron per pulse to eliminate the electron-electron coulomb interaction. Thus, a diffraction pattern can only be formed by accumulating millions of shots. The cold atom electron source, which has a transverse coherence greater than 15 nm and a peak brightness similar to conventional electron source's, is sufficient for some molecular systems in biochemistry. In short, with the improvement of coherence and the emergence of new electron sources, it is possible to reveal complex organic and inorganic structures, especially the dynamic behaviors of protein, and promote the understanding of nanoscale energy transport, solid-liquid and solid-gas interfacial dynamics and chemical reaction and so on. High-coherence electron sources not only serve in the diffraction experiments, but also play a key role in developing ultrafast electron microscopy, coherent diffraction imaging and ptychography. ? 2017 Chinese Physical Society.Accession Number: 20174204280614 -
Record 174 of
Title:Retrieval of total suspended particulate matter in highly turbid Hangzhou Bay waters based on geostationary ocean color imager
Author(s):Liu, Jia(1); Liu, Jiahang(1); He, Xianqiang(2); Chen, Tieqiao(1); Zhu, Feng(1); Wang, Yihao(1); Hao, Zengzhou(2); Chen, Peng(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10422 Issue: DOI: 10.1117/12.2278047 Published: 2017Abstract:Hangzhou Bay waters are often characterized by extremely high total suspended particulate matter (TSM) concentration due to terrestrial inputs, bottom sediment resuspension and human activities. The spatial-temporal variability of TSM directly contributes to the transport of carbon, nutrients, pollutants, and other materials. Therefore, it is essential to maintain and monitor sedimentary environment in coastal waters. Traditional field sampling methods limit observation capability for insufficient spatial-temporal resolution. Thus, it is difficult to synoptically monitor high diurnal dynamics of TSM. However, the in-orbit operation of the world's first geostationary satellite ocean color sensor, GOCI, thoroughly changes this situation with hourly observations of covered area. Taking advantage of GOCI high spatial-temporal resolution, we generated TSM maps from GOCI Level-1B data after atmospheric correction based on six TSM empirical algorithms. Validation of GOCI-retrieved normalized water-leaving radiances and TSM concentration was presented in comparison with matched-up in-situ measurements. The mean absolute percentage differences of those six TSM regional algorithms were 24.52%, 163.93%, 195.50%, 70.50%, 121.02%, 82.72%, respectively. In addition, the discrepancy reasons were presented, taking more factors such as diversified satellite data, various study area, and different research season into consideration. It is effective and indispensable to monitor and catch the diurnal dynamics of TSM in Hangzhou Bay coastal waters, with hourly GOCI observations data and appropriate inversion algorithm. ? 2017 SPIE.Accession Number: 20175104565896 -
Record 175 of
Title:Anchor-based group detection in crowd scenes
Author(s):Chen, Mulin(1); Wang, Qi(1); Li, Xuelong(2)Source: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings Volume: Issue: DOI: 10.1109/ICASSP.2017.7952382 Published: June 16, 2017Abstract:Group detection aims to classify pedestrians into categories according to their motion dynamics. It's fundamental for analyzing crowd behaviors and involves a wide range of applications. In this paper, we propose a Anchor-based Manifold Ranking (AMR) method to detect groups in crowd scenes. Our main contributions are threefold: (1) the topological relationship of individuals are effectively investigated with a manifold ranking method; (2) global consistency in crowds are accurately recognized by a coherent merging strategy; (3) the number of groups is decided automatically based on the similarity graph of individuals. Experimental results show that the proposed framework is competitive against the state-of-the-art methods. ? 2017 IEEE.Accession Number: 20172903954496 -
Record 176 of
Title:Tunable Narrowband Filter Based on Guided Mode Resonance
Author(s):Hei, Xu-Wei(1,2,3); Zhang, Ling-Xuan(2,3,4); Liu, Ji-Hong(1); Ge, Zhi-Qiang(2,3,4); Li, Si-Qi(2,3,4); Li, Xing-Yi(2,3,4); Wang, Guo-Xi(2,3,4); Wang, Lei-Ran(2,3,4); Zhang, Wen-Fu(2,3,4)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 12 DOI: 10.3788/gzxb20174612.1223001 Published: December 2017Abstract:A separated guided-mode resonance filter was presented, which is consisted of a grating layer and two planar dielectric waveguide layers partitioned by an air gap. The optical responses of the grating under different parameters are analyzed by time domain finite difference method. The research shows that the resonance wavelength of the grating can be tuned by varying the height of air gap when the TM polarization incident wave is applied.Furthermore, the resonance wavelengths almost vary in a linear relation respect to the height of air gap. A narrow linewidth characteristic can be obtained by applying a shallow grating. The simulation results show that the wavelength can be tuned from 1 515 to 1 558 nm with the FWHM less than 0.6 nm. ? 2017, Science Press. All right reserved.Accession Number: 20180404664653 -
Record 177 of
Title:Locality Adaptive Discriminant Analysis for Spectral-Spatial Classification of Hyperspectral Images
Author(s):Wang, Qi(1,2,3); Meng, Zhaotie(1,3); Li, Xuelong(4,5)Source: IEEE Geoscience and Remote Sensing Letters Volume: 14 Issue: 11 DOI: 10.1109/LGRS.2017.2751559 Published: November 2017Abstract: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. ? 2004-2012 IEEE.Accession Number: 20174904499324 -
Record 178 of
Title:Electro-optical design of a long slit streak tube
Author(s):Tian, Liping(1,2,3); Tian, Jinshou(1,3); Wen, Wenlong(1); Chen, Ping(1); Wang, Xing(1); Hui, Dandan(1,2); Wang, Junfeng(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10605 Issue: DOI: 10.1117/12.2295869 Published: 2017Abstract:A small size and long slit streak tube with high spatial resolution was designed and optimized. Curved photocathode and screen were adopted to increase the photocathode working area and spatial resolution. High physical temporal resolution obtained by using a slit accelerating electrode. Deflection sensitivity of the streak tube was improved by adopting two-folded deflection plates. The simulations indicate that the photocathode effective working area can reach 30mm × 5mm. The static spatial resolution is higher than 40lp/mm and 12lp/mm along scanning and slit directions respectively while the physical temporal resolution is higher than 60ps. The magnification is 0.75 and 0.77 in scanning and slit directions. And also, the deflection sensitivity is as high as 37mm/kV. The external dimension of the streak tube are only '.74mm×231mm. Thus, it can be applied to laser imaging radar system for large field of view and high range precision detection. ? 2017 SPIE.Accession Number: 20181705046990 -
Record 179 of
Title:Plasmonic Black Absorbers for Enhanced Photocurrent of Visible-Light Photocatalysis
Author(s):Tan, Furui(1,2); Wang, Ning(1,2); Lei, Dang Yuan(1,2); Yu, Weixing(3); Zhang, Xuming(1,2)Source: Advanced Optical Materials Volume: 5 Issue: 2 DOI: 10.1002/adom.201600399 Published: January 18, 2017Abstract:Plasmonic resonance of noble metal nanoparticles can drastically enhance the visible response of wide-bandgap photocatalysts such as TiO2, but the current technology has two fundamental problems: narrow absorption band and low absorption, which limit the energy efficiency of photocatalysis using sunlight. Here, an original plasmonic black absorber is reported, which sandwiches a 150 nm TiO2 layer between a layer of random Au nanoparticles and a rough Au surface (200 nm thick). The combined plasmonic effect of the Au nanoparticles and the Au rough surface enables a strong absorption (72%–91%) over 400–900 nm and a significantly (20-fold) enhanced photocurrent as compared to the bare TiO2 film. The strong absorption to visible and near infrared light, and the much enhanced photocurrent make the black absorber an ideal material for solar applications such as photocatalytic, photosynthetic, photovoltaic, and photothermal systems. ? 2016 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimAccession Number: 20164202908369 -
Record 180 of
Title:Magneto-optical effects of Ge-Ga-Sb(In)-S chalcogenide glasses with diamagnetic responses
Author(s):Chen, Gang(1,2); Xu, Yantao(1,3); Guo, Haitao(1); Cui, Xiaoxia(1); Wang, Pengfei(1); Lu, Min(1); Xiao, Xusheng(1,3); Guo, Quan(1,3); Peng, Bo(1)Source: Journal of the American Ceramic Society Volume: 100 Issue: 7 DOI: 10.1111/jace.14808 Published: July 1, 2017Abstract:The Faraday effects of Ge-Ga-Sb(In)-S serial chalcogenide glasses were investigated at the wavelengths of 635, 808, 980, and 1319 nm, respectively. The compositional dependences were analyzed and associated influencing factors including the absorption edge, the concentration of Sb3+/In3+ ions, and the wavelength dispersion of refraction index were discussed. 80GeS2·20Sb2S3 composition glass was found to have the largest Verdet constant (V=0.253, 0.219, 0.149, and 0.065 min·G?1·cm?1 for wavelengths 635, 808, 980, and 1319 nm, respectively) in these glasses, which is larger than that of commercial diamagnetic glasses (Schott, SF 6, V=0.069 min·G?1·cm?1@633 nm, for example). Sb3+ ions with high polarizability possessing s2-sp electron jumps involving 1S0→1P1, 3P0,1,2 transitions are responsible for large Verdet constant, and Becquerel rule is proved to be an effective guidance for estimating the Verdet constant and further optimizing the compositions in chalcogenide glasses. ? 2017 The American Ceramic SocietyAccession Number: 20172703897900