婷婷激情亚洲,色五月最新网址

2017

Record 445 of

Title:Test Method of Angle Error of Limited Rotation Axis System

Author(s):Tian, Liu-De(1,2); Zhao, Jian-Ke(1); Zhou, Yan(1); Wang, Tao(1); Zhao, Huai-Xue(1); Pan, Liang(1); Liu, Zhao-Hui(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 11 DOI: 10.3788/gzxb20174611.1112005 Published: November 1, 2017
Abstract:In order to improve the measurement accuracy of the angular error in the limited rotation axis system, the principle and method of measuring the angular error by autocollimation theodolite was used to analysis the error sources which affect the measurement result, the simulation results show that the tilt angle of the axis of the measured shaft is the main error source. Based on the accurate error model, the method to identify the misadjustment parameters and separate the introduced error by using the least squares estimation was proposed to realize the high precision measurement of angle error. The experiment was carried out with the accuracy of 2″ single-axis position turntable as tested object. The test results of conventional methods are -309.1″~428.6″, the test error is large, however, the test results of the proposed method are -0.89″~1.01″ and -1.01″~0.93″, the test error is 0.70″ and 0.78″, eliminating the test error introduced by equipment misadjustment. The method has the advantages of simple equipment and simple operation, and can realize the high precision measurement the angle error of the limited rotation axis system, can solve the problem of limited rotation axis systemengineering testing problem. ? 2017, Science Press. All right reserved.
Accession Number: 20175104560103
Record 446 of

Title:Alignment of focus-adjustable off-axis reflective optical system

Author(s):Zhang, Xue-Min(1); Song, Xing(1,2); Hou, Xiao-Hua(1); Li, Hua(1)
Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 25 Issue: 6 DOI: 10.3788/OPE.20172506.1458 Published: June 1, 2017
Abstract:A space interactive measurement and datum transmission system with high accuracy was proposed, aiming at precise alignment problem of off-axis reflective optical system. Therefore the highly accurate angle location of focusing angle and systemic optical axis was realized. The diameter of the system was 450 mm, and focus-adjustable range was from 0.5 km to infinity. After accurate positioning of focusing angles, only wave aberration of off-axis three-mirror optical system in infinite position needed to be adjusted to satisfy requirements, and the wave aberrations of all focus position in the system could be guaranteed to accord with design requirements, thus improving adjustment efficiency greatly. The experimental results show that the wave aberrations of the system in infinite position, 1.5 km, 2.5 km and 0.5 km are 0.1λ, 0.11λ, 0.5km and 0.2λ respectively, which are all better than design requirements. ? 2017, Science Press. All right reserved.
Accession Number: 20173104011338
Record 447 of

Title:Transmit-receive Isolation Analysis and Test of Cassegrain Optical Antenna

Author(s):Xia, Fang-Yuan(1,2,3); Yang, Jian-Feng(1); Yao, Zhou-Shi(3); Li, Shuai(3); Wang, Bo(3); Chen, Xiang(3)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 46 Issue: 10 DOI: 10.3788/gzxb20174610.1023001 Published: October 1, 2017
Abstract:Two schemes such as single pixel signal to noise ratio and extinction ratio are used to evaluate transmit-receive isolation ability based on the practical application of the tracking and communication detector in laser communication system. A method to inhibit the back scattering light was presented which boring a hole in the secondary mirror and increasing light trap. It is derived that when aperture ratio of secondary mirror K is 0.1~0.3, it dose not affect the emission efficiency, the measured results show that the improved Cassegrain optical antenna Transmit-Receive isolation is lower than -40 dB while not affecting the emission efficiency of system, and meet the requirements of laser communication system acquiring, tracking and communication. ? 2017, Science Press. All right reserved.
Accession Number: 20174504368393
Record 448 of

Title:Development of 2.5?THz suspended porous microstructured fiber based on cyclic-olefin copolymer

Author(s):Chen, Qi(1); Zhu, Wenjing(1); Kong, Depeng(2); He, Xiaoyang(1); Li, Bo(1); Miao, Jing(2); Luo, Zhenfei(3); Zhou, Xun(3); Yang, Chun(1); Zhang, Jian(1)
Source: Optik Volume: 145 Issue: DOI: 10.1016/j.ijleo.2017.06.124 Published: September 2017
Abstract:Efficient transmission of terahertz (THz) wave is very important in the development of THz technology. Polymer microstructured fiber is ideal in THz waveguide transmission for its advantages of low loss, low dispersion and good flexibility to bend. Based on the full vector finite element method, a suspended porous microstructured fiber with the operating frequency of 2.5?THz was designed. Fiber samples made of cyclic-olefin copolymer were fabricated, and their transmission performances were measured by using the CO2 pump laser THz source. The measured minimum loss is 0.17?dB/cm and average loss is about 0.5?dB/cm. The fluctuation of transmission loss is less than 5% when the fiber is bent from 0° to 90°, showing good flexibility of bending. The measured mode field distributions of the output tips show that the THz wave propagates with fundamental mode, and the energy is well confined in the core of the fiber. ? 2017 Elsevier GmbH
Accession Number: 20173003968760
Record 449 of

Title:A deep convolution neural network for object detection based

Author(s):Yue, Qi(1,2,3); Ma, Caiwen(1)
Source: Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology Volume: 49 Issue: 5 DOI: 10.11918/j.issn.0367-6234.201603145 Published: May 30, 2017
Abstract:Deep convolutional neural network (CNN) has too many parameters to initialize, and the usual random initialization method is easy to disappear of modified gradient and the problem of premature. The unsupervised PCA learning method is used to obtain oriented initialization parameters. And the gradient descendent method with exponential flexible momentum for updating free parameters of the network is proposed on the basis of analyzing the error propagation of the network. Image detection experiments are respectively carried out on pedestrian detection, and the results show that, compared with other artificial feature detection algorithms, this method can effectively improve target detection accuracy and the detection speed of this method is 20% faster than that of classical CNN; compared with homologous updating mechanism of other momentum, our method has faster convergence and smaller oscillation, and can improve the detection accuracy by 1.6%, 1.8% and 6.19% respectively in different depth models. ? 2017, Editorial Board of Journal of Harbin Institute of Technology. All right reserved.
Accession Number: 20173103998663
Record 450 of

Title:Influence of structural parameters on the laser precision tracking turntable

Author(s):Erfang, Cao(1,2); Wenji, She(2); Liang, Zhou(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10256 Issue: DOI: 10.1117/12.2268731 Published: 2017
Abstract:The laser tracker is composed of a mechanical structure and a servo control system. And the characteristics of them all affect the error and stability of the laser tracker measurement system. In the dynamic characteristics, the mechanical structure has its natural frequency and the servo control system has servo bandwidth. If the natural frequency closes to the servo bandwidth, the noise produced by system will have an influence on the stability and measure precision of the turntable. In order to make a laser tracker take a good performance, the natural frequency has to stay away from the range of the servo bandwidth. Based on this relationship between the natural frequency and servo bandwidth, construct and simplify a 3D model, analyze the influence of material stiffness, friction and rotary inertia on the natural frequency of a self-developed laser tracker turntable. Analysis shows that the natural frequency augments with the increase of material stiffness and reduction of rotary inertia and has nothing to do with friction. And factors of the structure material influence the different orders of natural frequency differently. These conclusions show that the kind of material with low density and high stiffness is more fitted to the turntable and provide references for optimization design of precision laser tracking turntable. ? 2017 SPIE.
Accession Number: 20171703607512
Record 451 of

Title:Modal analysis of collimation frame fabricated by titanium alloy

Author(s):Zhang, Yongqiang(1,2); Liu, Zhaohui(2); Li, Zhiguo(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10256 Issue: DOI: 10.1117/12.2268787 Published: 2017
Abstract:Collimation frame is the key supporting component of Space two-dimensional turntable. Its stiffness characteristics are vital for the performance of turntable. In order to reduce weight and improve rigidity, a lightweight collimation frame is designed. Compared with some commonly used aerospace materials, titanium alloy is chosen as the material of collimation frame for its excellent advantages. Modal analysis of the collimation frame is realized by using finite element analysis software MSC. Patran/Nastran to verify whether the stiffness of frame meet the design requirements. The results of analysis show that the first natural frequency of collimation frame is 169.5Hz, which satisfies the design requirement of stiffness. Then, modal experiment is conducted to verify the correctness of the results obtained from finite element modal analysis. The results of experiment show that simulation and experiment results agree well, which further confirm the correctness of the finite element modal analysis. Therefore, it proves that the selection of material and the design of structure are feasible. ? 2017 SPIE.
Accession Number: 20171703607610
Record 452 of

Title:FPGA implement method for two-dimensional integer wavelet transform in the space-based on-orbit image compression system

Author(s):Jie, Wang(1,2); Yan, Tian(1); Xiangsheng, Meng(1); Tong, Liu(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10256 Issue: DOI: 10.1117/12.2257416 Published: 2017
Abstract:The image obtained from space-based vision system has increasingly high frame frequency and resolution, and field of view is also growing. Due to the dramatic increase of data scale and the restriction of channel bandwidth between satellite and ground, on-orbit data compression becomes the core of on-satellite data processing. The paper analyzes the new generation static image compression standard JPEG2000 and the key two-dimensional (2D) discrete wavelet transform (DWT) technology. Then an FPGA (Field Programmable Gate Array)implement method for 2D integer wavelet transform is designed. It adopts the spatial combinative lifting algorithm (SCLA), which realizes the simultaneous transformation on rows and columns. On this basis, the paper realizes wavelet decomposition for images with a resolution of 6576?4384 (which is divided into 1024?1024) on the FPGA platform. In particular, the test platform is built in ISE14.7 simulation software, and the device model is xc5vfx100t. The design has passed the FPGA verification. In order to verify the correctness of the algorithm, the results are compared with that obtained by running matlab code. The experimental results show that the design is correct and the resource occupancy rate is low. ? 2017 SPIE.
Accession Number: 20171703607654
Record 453 of

Title:Visibility enhancement of hazy images using polarimetric dehazing method based on stokes parameters

Author(s):Liang, Jian(1,2); Zhang, Wenfei(1,2); Ren, Liyong(1); Ju, Haijuan(1,2); Bai, Zhaofeng(1); Qu, Enshi(1)
Source: 2017 Conference on Lasers and Electro-Optics, CLEO 2017 - Proceedings Volume: 2017-January Issue: DOI: 10.1364/CLEO_SI.2017.AM4B.5 Published: October 25, 2017
Abstract:Polarimetric dehazing methods are proven very effective in enhancing the contrast and visibility of images captured in hazy weather. In this paper, we analyze the capability of visibility enhancement in experiments. ? 2017 IEEE.
Accession Number: 20181304938231
Record 454 of

Title:Design and Calibration of Weak-Light Single Star Simulator

Author(s):Liu, Shangkuo(1,2); Xue, Xun(1); Li, Kun(1); Cao, Kun(1); Zhao, Jianke(1); Zhou, Yan(1); Yao, Baoli(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 37 Issue: 10 DOI: 10.3788/AOS201737.1012001 Published: October 10, 2017
Abstract:Aiming at the problem of high magnitude target simulation in the lab, a weak-light single star simulator (WLSSS) consisting of light source, adjustable diaphragm, integrating sphere, photoelectric detector and collimator is developed to measure the magnitude detecting ability of detecting cameras and star sensors. The relationship between the readings of photoelectric detector, the spectral radiance in the outlet of integrating sphere and tunable obscuration ratio is deduced. Combining the magnitude definition formula and the image illuminance equation formula, the operation principle of weak-light single star simulator is introduced, and the calibration challenge of high magnitude target is solved. The magnitude simulation range and precision of WLSSS are theoretically analyzed, and results show that the highest simulating magnitude is 19.5 Mv, and the precision is 11.6%. When the simulation magnitude is lower than 15 Mv, its precision is better than 8%. Experiment results show that in the lab, the maximum relative error between simulated magnitudes and KLL-04 wide-range illuminator tested magnitudes is 7.09%. The relative error of measured magnitude detecting ability between laboratory and astro-observation detecting cameras is 1.9% in 6.5 Mv, and 2.6% in 15.2 Mv. The designed WLSSS can effectively simulate high magnitude targets. ? 2017, Chinese Lasers Press. All right reserved.
Accession Number: 20175004531166
Record 455 of

Title:A new image fusion and monitored control system based on Raspberry Pi and Yeelink platform

Author(s):Gao, Wei(1); Shen, Chao(1); Song, Zongxi(1); Dan, Lijun(1); Wang, Fengtao(1); He, Yuqing(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2284474 Published: 2017
Abstract:Image fusion has been widely used in medical, computer vision and other fields. However, the traditional based on PC, FPGA and DSP image fusion system cannot satisfy requirements of portable, low power consumption and low cost.Raspberry Pi is a new type of microcomputer based on ARM, compared with traditional image fusion system, Raspberry Pi volume, price and power consumption is very low. With Raspberry Pi as core,and special camera of Raspberry Pi, router, PC, mouse, keyboard hardware, C++, OpenCV software, and Yeelink cloud platform build innovative image fusion system is able to meet small volume, low power and price requirements. Yeelink is a new type of Internet of things, providing access to sensor data, storage and display services. The terminal user can observe required information in real time through local area network. NonSubsampledContourlet Transform (NSCT) with multi-scale, multi-direction, multi-resolution and good shift invariance. Because of down sampling, traditional Contourlet transform will cause Gibbs phenomenon, NSCT can overcome the disadvantage, obtaining better fusion image. This paper makes full use of characteristic of Raspberry Pi and Yeelink, construct a new image fusion and scene monitoring system, images is processed by Wavelet, Contourlet and NSCT algorithms, finally analysis the results. The new system has great research and application value. ? 2017 SPIE.
Accession Number: 20180404671136
Record 456 of

Title:Discrete Nonnegative Spectral Clustering

Author(s):Yang, Yang(1); Shen, Fumin(1); Huang, Zi(2); Shen, Heng Tao(1); Li, Xuelong(3)
Source: IEEE Transactions on Knowledge and Data Engineering Volume: 29 Issue: 9 DOI: 10.1109/TKDE.2017.2701825 Published: September 1, 2017
Abstract:Spectral clustering has been playing a vital role in various research areas. Most traditional spectral clustering algorithms comprise two independent stages (e.g., first learning continuous labels and then rounding the learned labels into discrete ones), which may cause unpredictable deviation of resultant cluster labels from genuine ones, thereby leading to severe information loss and performance degradation. In this work, we study how to achieve discrete clustering as well as reliably generalize to unseen data. We propose a novel spectral clustering scheme which deeply explores cluster label properties, including discreteness, nonnegativity, and discrimination, as well as learns robust out-of-sample prediction functions. Specifically, we explicitly enforce a discrete transformation on the intermediate continuous labels, which leads to a tractable optimization problem with a discrete solution. Besides, we preserve the natural nonnegative characteristic of the clustering labels to enhance the interpretability of the results. Moreover, to further compensate the unreliability of the learned clustering labels, we integrate an adaptive robust module with 2,p loss to learn prediction function for grouping unseen data. We also show that the out-of-sample component can inject discriminative knowledge into the learning of cluster labels under certain conditions. Extensive experiments conducted on various data sets have demonstrated the superiority of our proposal as compared to several existing clustering approaches. ? 1989-2012 IEEE.
Accession Number: 20173804172486

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