2014
2014
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Record 301 of
Title:Infrared emission properties of Dy3 +-doped and Dy 3 +,Tm3 +-codoped chalcohalide glasses
Author(s):Gu, Shaoxuan(1); Pi, Daoxian(1); Tao, Haizheng(1); Zeng, Qi(1); Zhao, Xiujian(1); Guo, Haitao(2); Chen, Hongyan(3)Source: Journal of Non-Crystalline Solids Volume: 383 Issue: DOI: 10.1016/j.jnoncrysol.2013.05.041 Published: January 1, 2014Abstract:Series of 76GeS2·19Ga2S3· 5AgCl (GGA) chalcohalide glasses doped with or codoped with Dy3 +, Tm3 + were prepared in this work. Systematical detection of absorption and emission spectra in the near-infrared and mid-infrared region was conducted. For the Dy3 + sole-doped GGA chalcohalide glasses, mainly due to the relatively low efficiency of pumping absorption and poor radiative transition probabilities of mid-infrared emissions, the mid-infrared emissions were hardly to be detected. Through the codoping of Tm3 + with high concentration, several intrinsical processes including the enhancement of pumping absorptive efficiency at 808 nm, cross relaxation process of Tm 3 +: 3H4 + 3H6 → 3F4 + 3F4 and energy transfer process of Tm3 +: 3F4 → Dy3 +: 6H11/2 are carried out, therefore relatively strong mid-infrared emissions at about 2900 and 4300 nm have been clearly observed. ? 2013 Elsevier B.V. All rights reserved.Accession Number: 20135117098586 -
Record 302 of
Title:In defense of iterated conditional mode for hyperspectral image classification
Author(s):Lin, Jianzhe(1,3); Wang, Qi(2); Yuan, Yuan(1)Source: Proceedings - IEEE International Conference on Multimedia and Expo Volume: 2014-September Issue: Septmber DOI: 10.1109/ICME.2014.6890171 Published: September 3, 2014Abstract:Hyperspectral image classification is one of the most significant topics in remote sensing. A large number of methods have been proposed to improve the classification accuracy. However, the improvement often comes at the cost of higher complexity. In this work, we mainly focus on the Markov Random Fields related paradigm, which involves a demanding energy minimization procedure. Traditional methods are prone to employ the advanced optimization techniques. On the contrary, this paper is in defense of a simple yet efficient method for hyperspectral image classification, Iterated Conditional Mode, which has been generally considered inferior to other state-of-the-art methods. Our purpose is successfully achieved by tackling two inherent drawbacks of ICM, sensitive label initialization and local minimum. We apply our method to three real-world hyperspectral images, and compare the results with those of state-of-the-art methods. The comparisons show that the proposed method outperforms its competitors. ? 2014 IEEE.Accession Number: 20153001066654 -
Record 303 of
Title:A nonlinear adaptive level set for image segmentation
Author(s):Wang, Bin(1); Gao, Xinbo(1); Tao, Dacheng(2); Li, Xuelong(3)Source: IEEE Transactions on Cybernetics Volume: 44 Issue: 3 DOI: 10.1109/TCYB.2013.2256891 Published: March 2014Abstract:In this paper, we present a novel level set method (LSM) for image segmentation. By utilizing the Bayesian rule, we design a nonlinear adaptive velocity and a probability-weighted stopping force to implement a robust segmentation for objects with weak boundaries. The proposed method is featured by the following three properties: 1) it automatically determines the curve to shrink or expand by utilizing the Bayesian rule to involve the regional features of images; 2) it drives the curve evolve with an appropriate speed to avoid the leakage at weak boundaries; and 3) it reduces the influence of false boundaries, i.e., edges far away from objects of interest. We applied the proposed segmentation method to artificial images, medical images and the BSD-300 image dataset for qualitative and quantitative evaluations. The comparison results show the proposed method performs competitively, compared with the LSM and its representative variants. ? 2013 IEEE.Accession Number: 20141017433612 -
Record 304 of
Title:Two different output states from an all-normal dispersion yetterbium-doped fiber laser using graphene-oxide as a saturable absorber
Author(s):Huang, S.S.(1); Wang, Y.G.(2); Yan, P.G.(1); Zhang, G.L.(1); Zhao, J.Q.(1); Li, H.Q.(1); Lin, R.Y.(1)Source: Laser Physics Volume: 24 Issue: 6 DOI: 10.1088/1054-660X/24/6/065108 Published: June 2014Abstract:We have experimentally obtained two different applied output states from an all-normal dispersion yetterbium-doped fiber laser using graphene-oxide as a saturable absorber without additional components (like tunable filter, dispersion compensation), including the wavelength-switched mode-locking operation, and the dissipative soliton resonance (DSR) operation with high energy square pulses. These two experimental phenomena indicate that the graphene-oxide saturable absorber can be successfully used to realize different mode-locking states in a fiber laser by system-parameter management. The yetterbium-doped fiber laser in all-normal dispersion with flexible outputs can meet different application needs. ? 2014 Astro Ltd.Accession Number: 20142617868985 -
Record 305 of
Title:Distributed object detection with linear SVMs
Author(s):Pang, Yanwei(1); Zhang, Kun(1); Yuan, Yuan(2); Wang, Kongqiao(3)Source: IEEE Transactions on Cybernetics Volume: 44 Issue: 11 DOI: 10.1109/TCYB.2014.2301453 Published: November 2014Abstract:In vision and learning, low computational complexity and high generalization are two important goals for video object detection. Low computational complexity here means not only fast speed but also less energy consumption. The sliding window object detection method with linear support vector machines (SVMs) is a general object detection framework. The computational cost is herein mainly paid in complex feature extraction and innerproduct-based classification. This paper first develops a distributed object detection framework (DOD) by making the best use of spatial-temporal correlation, where the process of feature extraction and classification is distributed in the current frame and several previous frames. In each framework, only subfeature vectors are extracted and the response of partial linear classifier (i.e., subdecision value) is computed. To reduce the dimension of traditional block-based histograms of oriented gradients (BHOG) feature vector, this paper proposes a cell-based HOG (CHOG) algorithm, where the features in one cell are not shared with overlapping blocks. Using CHOG as feature descriptor, we develop CHOG-DOD as an instance of DOD framework. Experimental results on detection of hand, face, and pedestrian in video show the superiority of the proposed method. ? 2014 IEEE.Accession Number: 20144500160052 -
Record 306 of
Title:Controlling optical bistability via interacting double dark resonances in linear quantum dot molecules
Author(s):Tian, Si-Cong(1); Wan, Ren-Gang(2); Tong, Cun-Zhu(1); Ning, Yong-Qiang(1)Source: Journal of the Optical Society of America B: Optical Physics Volume: 31 Issue: 11 DOI: 10.1364/JOSAB.31.002681 Published: November 1, 2014Abstract:The behavior of optical bistability (OB) in linear triple quantum dot molecules (QDMs) using double tunneling coupling by means of a unidirectional ring cavity is investigated. The linear and nonlinear susceptibilities of the system are also investigated. The double tunneling between the quantum dots can induce the interaction of double dark resonances, which can enhance the nonlinear response of the system. The type, the hysteresis loop, and the threshold of OB can be controlled by the intensity of the double tunneling and the detuning of the probe field. Our results give insights for future experiments and applications in optics using QDMs. ? 2014 Optical Society of America.Accession Number: 20144700234976 -
Record 307 of
Title:Surface waves at the interface between a metal and a photovoltaic- photorefractive crystal
Author(s):Li, Kehao(1); Lu, Keqing(2,4); Zhang, Yiqi(3); Hui, Juanli(2); Niu, Pingjuan(2); Yu, Liyuan(2); Zhang, Yanpeng(3)Source: Optik Volume: 125 Issue: 12 DOI: 10.1016/j.ijleo.2013.12.033 Published: June 2014Abstract:We investigate surface waves at the interface between a metal and a photovoltaic-photorefractive (PP) crystal. These surface waves appear in several forms: delocalized surface waves, shock surface waves, and localized surface waves. Only localized surface waves have limited energy. We demonstrate that the transverse sizes of localized surface waves decrease with an increase in the propagation constant and the amplitudes of localized surface waves increase with the propagation constant. The stability of localized surface waves is investigated numerically and it is found that they are stable. ? 2014 Elsevier GmbH. All rights reserved.Accession Number: 20142217757281 -
Record 308 of
Title:Enhanced near infrared luminescence efficiency of ligand-free LaF 3:Nd/LaF3 core/shell nanocrystals in solvent dispersion
Author(s):Cui, Xiaoxia(1); Guo, Haitao(1); Hou, Chaoqi(1); Gao, Fei(1); Wei, Wei(1,2); Peng, Bo(1,2)Source: Journal of Luminescence Volume: 154 Issue: DOI: 10.1016/j.jlumin.2014.04.019 Published: October 2014Abstract:A variety of ligand-free LaF3:Nd/LaF3 core/shell nanocrystals with high quantum efficiency, great dispersibility and low quench ratio was prepared by a simple solvothermal method. Their phase and morphologies were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The optical properties of the samples prepared under different times were investigated. The core/shell nanocrystals have great dispersibility concentration (312 mg/mL) in dimethyl sulfoxide (DMSO)/tetrabromoethane solvents. These transparent colloidal solution exhibits enhanced high quantum efficiency (61.2%) at 1057 nm. Therefore, the LaF3:Nd/LaF3 core/shell nanocrystals with excellent near infrared to near infrared (NIR-to-NIR) fluorescence are a promising candidate for luminescence material in liquid media. ? 2014 Elsevier B.V.Accession Number: 20142117750697 -
Record 309 of
Title:Study on writing of double line waveguide in Yb:YAG with ultrafast laser
Author(s):Tang, Wenlong(1,2); Song, Qiongge(1,2); Xu, Qing'an(3); Liu, Xin(1,2); Cheng, Guanghua(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 34 Issue: 12 DOI: 10.3788/AOS201434.1232002 Published: December 10, 2014Abstract:The writing of double line waveguide in Yb3+ doped yttrium aluminum garnet (Yb:YAG) crystal is studied by using titanium sapphire laser with the pulse width of 160 fs, central wavelength of 775 nm and repetition frequency of 50 kHz. The phenomenon of polarization guiding is discovered in the waveguide. The laser with polarization parallel to the direction of double line can be guided, but the laser with polarization perpendicular to the direction of double line cannot be guided. The effects of written parameters, such as double line separation, laser pulse energy and writing speed, on the formation of the waveguide are analyzed. Experimental results show that the waveguide has the good property of guiding under the writing conditions of double line separation of 30 μm, writing speed of 400 μm/s and pulse energy of 5.0 μJ. Bivariate distribution of the waveguide refractive index is reconstructed by near-field mode and the maximum refractive index change is 1.8×10-4. A continuous waveguide laser with a wavelength of 1030.5 nm is obtained and the output power is 4.7 mW. ?, 2014, Chinese Optical Society. All right reserved.Accession Number: 20145300387473 -
Record 310 of
Title:Correct non-uniformity of scientific grade CCD in measuring laser near field distributing
Author(s):Lin, Hui(1); Liu, Lili(1); Tian, Xinfeng(1); Hao, Yun(2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 7 DOI: Published: July 25, 2014Abstract:The reason of photo response non-uniformity (PRNU) of image sensor's photo response was analyzed in this paper at first. It was concluded in two faces, one caused by spatial noise which based on materials, manufacture crafts and offset and another caused by temporal noise which based on its response with time drift, theses two factors influence the PRNU of image sensor's photo response gravely. To describe the affection of spatial noise and temporal noise, the model of sensor based on the hypothesis that linear of image sensor's photo response was made, and the erase non-uniformity of CCD by Least Square Methods based on this model was proposed. Experiment results show that the proposed algorithm is effective to the correction of image sensor's PRNU.Accession Number: 20143600062395 -
Record 311 of
Title:Digital holographic microscopy with phase-shift-free structured illumination
Author(s):Zheng, Juanjuan(1); Gao, Peng(1,2); Yao, Baoli(1); Ye, Tong(3); Lei, Ming(1); Min, Junwei(1); Dan, Dan(1); Yang, Yanlong(1); Yan, Shaohui(1)Source: Photonics Research Volume: 2 Issue: 3 DOI: 10.1364/PRJ.2.000087 Published: 2014Abstract:When structured illumination is used in digital holographic microscopy (DHM), each direction of the illumination fringe is required to be shifted at least three times to perform the phase-shifting reconstruction. In this paper, we propose a scheme for spatial resolution enhancement of DHM by using the structured illumination but without phase shifting. The structured illuminations of different directions, which are generated by a spatial light modu-lator, illuminate the sample sequentially in the object plane. The formed object waves interfere with a reference wave in an off-axis configuration, and a CCD camera records the generated hologram. After the object waves are reconstructed numerically, a synthetic aperture is performed by an iterative algorithm to enhance the spatial resolution. The resolution improvement of the proposed method is proved and demonstrated by both simulation and experiment. ? 2014 Chinese Laser Press.Accession Number: 20182705409378 -
Record 312 of
Title:Grid-controlled emission source for space X-ray communication
Author(s):Ma, Xiao-Fei(1,2); Zhao, Bao-Sheng(1); Sheng, Li-Zhi(1); Liu, Yong-An(1); Liu, Duo(1,2); Deng, Ning-Qin(3)Source: Wuli Xuebao/Acta Physica Sinica Volume: 63 Issue: 16 DOI: 10.7498/aps.63.160701 Published: August 20, 2014Abstract:Using X-ray as carrier signal to realize the high rate information transmission in a distant space is attracting the attention of researchers. The development of this technology has a positive significance for broadening the scope of use of the electromagnetic spectrum. In this paper, the novel grid control X-ray source, which consists of a traditional X-ray tube and a signal control grid, is designed to meet the requirements of X-ray communication in the simulation vacuum experimental system by means of three-dimensional electromagnetic simulation software CST particle studio. The tube potential distribution, electron trajectory, actual focal spot and the number of electrons at the anode are simulated by the computer simulation software. It works by changing the grid voltage to control the X-ray pulse emission. The data of the simulation are as follows. The actual focal spot size is 0.4 mm × 4 mm, the effective gate-on voltage is 0 V, and the gate-off voltage is -10 V. X-ray tube grid-controlled characteristics are tested in experiment. The test results are well consistent with the simulation results. Finally, the digital signal transmission is successfully implemented in the X-ray vacuum experiment system. ? 2014 Chinese Physical SocietyAccession Number: 20143900071436