2016
2016
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Record 349 of
Title:Thermal-structural coupled analysis and verification of 2-D mirror gimbal for lunar-based telescope
Author(s):Shangguan, Ai-Hong(1,2); Wang, Chen-Jie(1,3); Zhang, Hao-Su(1,2); Qin, De-Jin(1); Liu, Zhao-Hui(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 24 Issue: 8 DOI: 10.3788/OPE.20162408.1956 Published: August 1, 2016Abstract:To improve the work performance of a 2-D mirror gimbal for the lunar-based telescope, the thermal-structural coupled analysis was carried out, and the analysis results were verified by thermal and onboard tests. According to the given input conditions, thermal loads and the thermal boundary, the finite element model was established to calculate the temperature fields of the mirror gimbal and main heating components. Through inputting the temperature loads, preloads and the boundary conditions into the finite element model, the thermal deformation and stress of the U-shape structure, precision moving shafting systems and the worm gears were obtained. Then, the expressions of friction moment were derived, and analytical data were used to the expressions to achieve the friction moment of shafting systems. On the basis of the friction moment, a proper moment motor was chosen. After calculation, the results show that the left shafting system has a larger friction moment at the low temperature condition of -25℃, and the maximal one is up to 14.163 N·mm; While the friction moment is smaller under high temperature condition 55℃, and the maximal one is 4.796 N·mm. The results also show friction moment of the azimuth shafting systems at a low temperature condition of -25℃ is 16.45 N·mm. Moreover, the vertical shaft system shows its friction moment to be 16.45 N·mm at the low temperature condition of -25℃, while it is zero at the high temperature condition because of shafting system unloading. The results indicate the reflection mirror gimbal works well between -25℃ to 55℃. Finally, the thermal and onboard tests were carried out to demonstrate the rationality and validity of the analysis results. ? 2016, Science Press. All right reserved.Accession Number: 20163802821852 -
Record 350 of
Title:Scalable Linear Visual Feature Learning via Online Parallel Nonnegative Matrix Factorization
Author(s):Zhao, Xueyi(1); Li, Xi(2,6); Zhang, Zhongfei(1,3); Shen, Chunhua(4); Zhuang, Yueting(2); Gao, Lixin(5); Li, Xuelong(2,6)Source: IEEE Transactions on Neural Networks and Learning Systems Volume: 27 Issue: 12 DOI: 10.1109/TNNLS.2015.2499273 Published: December 2016Abstract:Visual feature learning, which aims to construct an effective feature representation for visual data, has a wide range of applications in computer vision. It is often posed as a problem of nonnegative matrix factorization (NMF), which constructs a linear representation for the data. Although NMF is typically parallelized for efficiency, traditional parallelization methods suffer from either an expensive computation or a high runtime memory usage. To alleviate this problem, we propose a parallel NMF method called alternating least square block decomposition (ALSD), which efficiently solves a set of conditionally independent optimization subproblems based on a highly parallelized fine-grained grid-based blockwise matrix decomposition. By assigning each block optimization subproblem to an individual computing node, ALSD can be effectively implemented in a MapReduce-based Hadoop framework. In order to cope with dynamically varying visual data, we further present an incremental version of ALSD, which is able to incrementally update the NMF solution with a low computational cost. Experimental results demonstrate the efficiency and scalability of the proposed methods as well as their applications to image clustering and image retrieval. ? 2015 IEEE.Accession Number: 20173404066986 -
Record 351 of
Title:Speckle phase retrieval and transmission matrix obtaining of turbid media
Author(s):Zhou, Libin(1,2); Zhuang, Bin(3); Sun, Hao(1,4); He, Zhengquan(3); Hu, Manli(1); Qiao, Xueguang(1)Source: Optik Volume: 127 Issue: 20 DOI: 10.1016/j.ijleo.2016.07.091 Published: October 1, 2016Abstract:Previous research has demonstrated that distorted images caused by turbid media can be reconstructed by turbid lens imaging (TLI) method. In this way, it's critical to accurately obtain the transmission matrix (TM) of turbid media. In this letter, we propose an improved method which is still based on Hilbert transform to get the transmission matrices, but it will use four images for each transmission matrix element to eliminate the influence of speckle intensity variation. In addition, a Hanning window filter is introduced to reduce the white Gaussian noise of original images to improve the result of TLI method. ? 2016 Elsevier GmbHAccession Number: 20163202691345 -
Record 352 of
Title:Image amplification based super-resolution reconstruction procedure designed for wavefront-coded imaging system
Author(s):Zhao, Hui(1); Zong, Caihui(1,2); Wei, Jingxuan(3); Xie, Xiaopeng(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10021 Issue: DOI: 10.1117/12.2245765 Published: 2016Abstract:Wave-front coding, proposed by Dowski and Cathey in 1995, is widely known to be capable of extending the depth of focus (DOF) of incoherent imaging systems. However, benefiting from its very large point spread function (PSF) generated by a suitably designed phase mask that is added to the aperture plane, wave-front coding could also be used to achieve super-resolution without replacing the current sensor with one of smaller pitch size. An image amplification based super-resolution reconstruction procedure has been specifically designed for wave-front coded imaging systems and its effectiveness has been tested by experiment. For instance, for a focal length of 50 mm and f-number 4.5, objects within the range [5 m, a?] are clearly imaged with the help of wave-front coding, which indicates a DOF extension ratio of approximately 20. The proposed super-resolution reconstruction procedure produces at least 3× resolution improvement, with the quality of the reconstructed super-resolution image approaching the diffraction limit. ? 2016 SPIE.Accession Number: 20170603327014 -
Record 353 of
Title:Dynamic properties of a small-size streak tube
Author(s):Hui, Dan-Dan(1,2); Tian, Jin-Shou(1); Wang, Jun-Feng(1); Lu, Yu(1); Wen, Wen-Long(1); Xu, Xiang-Yan(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 65 Issue: 1 DOI: 10.7498/aps.65.018502 Published: January 5, 2016Abstract:Scannerless (flash) lidar system based on streak camera is able to realize three-dimensional (3D) multi-spectral fluorescence imaging and 3D imaging polarimetry. Compared with conventional lidar system, the flash lidar system overcomes image distortions caused by the motion between the target and the sensor platform. Other advantages of the flash lidar system are higher image update rates and the potential for creating a miniaturized lidar system. To meet the requirements for developing this new technology, a super small-sized, large photocathode area and meshless streak tube with spherical cathode and screen is designed with the aid of computer simulation technology (CST) software. The tube with nearly 28 mm wide photocathode work area contains two electrostatic focusing lens, a pair of deflection plates, and a 50 mm diameter output screen. The external dimension of the tube is merely 50 mm×100 mm. And its electromagnetic fields are calculated in the CST Particle Studio based on the finite integration theory. Some dynamic properties of the tube are analyzed via observing different electron trajectories launched from a number of different points on the cathode. The influences of the deflector position on deflection sensitivity and spatial resolution are analyzed. Increasing the distance between the deflector and the anode pin hole leads to a worse deflection sensitivity but a better spatial resolution. As for the temporal resolution, three electron pulses separated by 30 ps can be well resolved by the streak tube in the dynamic mode. Thus, the dynamic temporal resolution of the streak tube is better than 30 ps. And a 10 lp/mm spatial resolution across the 28 mm long slit on the photocathode can be obtained by estimating modulation transfer functions of the electron trajectories. Temporal distortions at the entire photocathode working area are evaluated, and the data reveal that the larger the photocathode working area, the bigger the temporal distortions are. Also, the temporal distortion is present mainly in the photocathode-to-deflection plates region. In addition, the slit image of the streak tube working in the dynamic mode is simulated and presented. The phenomenon that the slit image is curved due to the temporal distortion is analyzed. Two rectangular electron pulses separated by 50 ps are well resolved by the streak tube. Therefore, the temporal resolution of this small-size steak tube is better than 50 ps with a rectangular slit dimension of 30 mm×50 μm on the photocathode, and its electron-optic magnification is 1.2. ? 2016 Chinese Physical Society.Accession Number: 20160601889295 -
Record 354 of
Title:Polarization imaging based on compressed sensing theory
Author(s):Wang, Peng(1,2); Rong, Zhibin(3); He, Junhua(1); Lv, Pei(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 45 Issue: 2 DOI: 10.3788/IRLA201645.0228005 Published: February 25, 2016Abstract:Polarization imaging technology is a method that acquires the object images by collecting the polarization information of the target radiation or reflected signals. In particular, compared with the light intensity detection, it has unique advantages in the artificial target detection and surface recognition. Due to the short range and low quality of the conventional polarization imaging in complex imaging environment, a new kind of polarization imaging technology based on compressed sensing was proposed. The basic principle of compressed sensing theory was elaborated. By constructing reasonable sampling matrix and reconstruction algorithm, the specific imaging system was designed. Besides, the feasibility of this technology was confirmed through the imaging experiment. The study results in the air show the system can reconstruct the polarization images of the pre-positioned target. Additionally, in the existing experimental conditions, some measures are investigated and proposed to improve the system imaging performance. ? 2016, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.Accession Number: 20161602245074 -
Record 355 of
Title:Joint multilabel classification with community-aware label graph learning
Author(s):Li, Xi(1); Zhao, Xueyi(2,3); Zhang, Zhongfei(2,4); Wu, Fei(1); Zhuang, Yueting(1); Wang, Jingdong(5); Li, Xuelong(6)Source: IEEE Transactions on Image Processing Volume: 25 Issue: 1 DOI: 10.1109/TIP.2015.2503700 Published: January 2016Abstract:As an important and challenging problem in machine learning and computer vision, multilabel classification is typically implemented in a max-margin multilabel learning framework, where the inter-label separability is characterized by the sample-specific classification margins between labels. However, the conventional multilabel classification approaches are usually incapable of effectively exploring the intrinsic inter-label correlations as well as jointly modeling the interactions between inter-label correlations and multilabel classification. To address this issue, we propose a multilabel classification framework based on a joint learning approach called label graph learning (LGL) driven weighted Support Vector Machine (SVM). In principle, the joint learning approach explicitly models the inter-label correlations by LGL, which is jointly optimized with multilabel classification in a unified learning scheme. As a result, the learned label correlation graph well fits the multilabel classification task while effectively reflecting the underlying topological structures among labels. Moreover, the inter-label interactions are also influenced by label-specific sample communities (each community for the samples sharing a common label). Namely, if two labels have similar label-specific sample communities, they are likely to be correlated. Based on this observation, LGL is further regularized by the label Hypergraph Laplacian. Experimental results have demonstrated the effectiveness of our approach over several benchmark data sets. ? 2015 IEEE.Accession Number: 20170303261314 -
Record 356 of
Title:Study of fourier transform imaging spectrometer with wide field of view
Author(s):Zhang, Zhinan(1,2); Li, Libo(1,2); Hu, Bingliang(1); Feng, Yutao(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 36 Issue: 1 DOI: 10.3788/AOS201636.0130001 Published: January 10, 2016Abstract:In order to meet the demand of wide field of view (FOV), wide swath width, and high throughput for the ocean spectrum, a new Fourier transform imaging spectrometer with wide FOV based on the image plane interference technologies presented. And the principle and expressions of the image plane interference are studied and educed.The optical system is designed and optimized based on the calculated detailed parameters. Dyson and double Gauss structures are used in the relay lensand fore optics respectively. Under the circumstance of 400~900 nm spectral range, 35.5° FOV, 320 km swath width, F/4, and 100 mm focal length, the average signal noise ratio (SNR) is greater than 100and the modulation transfer function (MTF) of the current design is greater than 0.5 at 32 lp/mm. All the parameters are well satisfied by the present design. ? 2016, Chinese Laser Press. All right reserved.Accession Number: 20161202115118 -
Record 357 of
Title:Numerical simulation study on quantum efficiency characteristics of InP/InGaAs/InP infrared photocathode
Author(s):Xu, Junkai(1,2,3); Xu, Xiangyan(1,3); Tian, Jinshou(1,3); Luo, Duan(1,2,3); Hui, Dandan(1,2,3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10157 Issue: DOI: 10.1117/12.2247394 Published: 2016Abstract:The quantum efficiency characteristics of InP/In0.53Ga0.47As/InP photocathode which is one of the field-assisted negative electron affinity photocathodes with III-V compound semiconductor and works at transmission mode with a wide1 spectral response range from 1.0-1.7 μm were studied in this paper. Under certain field-assisted bias voltage, internal quantum efficiency at different wavelength versus structure parameters and doping concentration of the photocathode was simulated by the APSYS program. Results show that: First, internal quantum efficiency of the photocathode rises with the increasing of the field-assisted bias voltage. Second, the internal quantum efficiency gradually increases to a maximum at thickness=0.2um of P-InGaAs photo-absorbing layer and then reduces with the increasing of thickness. However, doping concentration of P-InGaAs photo-absorbing layer has little influence on it. Third, the internal quantum efficiency reduces with the increasing of thickness and doping concentration of P-InP photoelectron-emitting layer. The optimization results show that when the thickness of the photo-absorbing layer and the photoelectron-emitting layer are both 0.2 μm, and the doping concentration of the photo-absorbing layer and the photoelectron-emitting layer are about 1.5×1015 cm-3 and 1.0×1016 cm-3respectively, under a certain field-assisted bias voltage, the line of the external quantum efficiency versus wavelength is ideal. Besides, the response time of photocathode can be reduced to less than 50 ps. ? 2016 SPIE.Accession Number: 20170503310026 -
Record 358 of
Title:The study of 700mm-diameter primary mirror based on topology optimization and sensitivity analysis
Author(s):Wang, Xin(1); He, Xiaoying(1); Jing, Juanjuan(1); Feng, Lei(1); Zhou, Jinsong(1); Wang, Wei(2); Li, Yacan(1); Wei, Lidong(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10021 Issue: DOI: 10.1117/12.2247143 Published: 2016Abstract:The primary mirror is an important optical component of space camera. Its performance related to the optical image quality, and the weight directly affects the whole camera weight. The traditional design of primary mirror relies on much experience, lacking of precise theory, and many design parameters obtained by empirical formulas, thus the performance of the result is unstable. For this study, a primary mirror made of SiC with the diameter of 700mm was conceptual designed to get the optimized structure. Then sensitivity analysis was carried out to determine the optimum thickness of the back muscles. Finally, the optimum primary mirror fully satisfied the required was completed, with outstanding mechanical performance and light weight. A comparison between the optimum primary and traditional primary was performed and the results showed that the optimum primary has higher lightweight ratio increased by 5%, higher modal frequency increased by 81Hz.The maximum deformation under gravity reduced by 48nm, PV of the mirror surface reduced by 8.1nm and RMS reduced by 3.1nm. All the results indicated that the optimization method in the paper is reasonable and effective, which gives a reference to the primary mirror design in the future. ? 2016 SPIE.Accession Number: 20170603327030 -
Record 359 of
Title:Biomimetic microchannels of planar reactors for optimized photocatalytic efficiency of water purification
Author(s):Liao, Wuxia(1,2); Wang, Ning(3,4); Wang, Taisheng(1); Xu, Jia(1); Han, Xudong(1); Liu, Zhenyu(1); Zhang, Xuming(3,4); Yu, Weixing(5)Source: Biomicrofluidics Volume: 10 Issue: 1 DOI: 10.1063/1.4942947 Published: January 01, 2016Abstract:This paper reports a biomimetic design of microchannels in the planar reactors with the aim to optimize the photocatalytic efficiency of water purification. Inspired from biology, a bifurcated microchannel has been designed based on the Murray's law to connect to the reaction chamber for photocatalytic reaction. The microchannels are designed to have a constant depth of 50 μm but variable aspect ratios ranging from 0.015 to 0.125. To prove its effectiveness for photocatalytic water purification, the biomimetic planar reactors have been tested and compared with the non-biomimetic ones, showing an improvement of the degradation efficiency by 68%. By employing the finite element method, the flow process of the designed microchannel reactors has been simulated and analyzed. It is found that the biomimetic design owns a larger flow velocity fluctuation than that of the non-biomimetic one, which in turn results in a faster photocatalytic reaction speed. Such a biomimetic design paves the way for the design of more efficient planar reactors and may also find applications in other microfluidic systems that involve the use of microchannels. ? 2016 AIP Publishing LLC.Accession Number: 20161002060165 -
Record 360 of
Title:Development of wide field of view technology of synthetic aperture lidar
Author(s):Li, Yi-Zhe(1,2); Xue, Bin(2); Zhao, Yi-Yi(2)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 24 Issue: DOI: 10.3788/OPE.20162413.0300 Published: October 1, 2016Abstract:The development of Synthetic Aperture Ladar (SAL) both at domestic and abroad was reviewed, where the technical difficulties in its application and practice were introduced. Among these problems, the solutions to that of narrow field of view (FOV) were analyzed, demonstrating theoretical restriction in FOV of heterodyne detection in SAL. The endeavor and exploration of wide FOV SAL were summarized at home and abroad. Finally, the future development prospect of SAL was described and analyzed. ? 2016, Science Press. All right reserved.Accession Number: 20165003105774