2021
2021
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Record 133 of
Title:Design of the Active Cooling Focal Plane Component for the Space Astronomy Telescope
Author(s):Liangjie, Feng(1); Chenjie, Wang(1); Gangyi, Zou(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12075 Issue: DOI: 10.1117/12.2605265 Published: 2021Abstract:The detecting CCD of a space astronomical telescope needs to be cooled to -75℃ to suppress the dark current for faint target detecting in the universe, and coplanarly spliced with two fine guidance sensor(FGS) which needs to be cooled to -40℃ for the stability as long time observation. Two one stage thermos-electric cooler(TEC) was connected to actively cool the detector to ensure the working temperature and the temperature control accuracy, the Structural of the actively cooling detector assembly and the focal plane component were presented and the power dissipation of the TEC was calculated. In order to ensure the coplanarity of the focal plane component on the working temperature, the finite element method was used to analyze the thermal distribution on the detector surface and the thermal deformation of the supporting structure of the FGS with different materials. The analysis results showed that the lowest cooling temperature of the detecting CCD is -75℃, the temperature control accuracy was better than 1℃, and the coplanar error of the detection CCD and the fine guidance sensors did not exceed 20μm. The thermal equilibrium test showed that the lowest cooling temperature was -74.9℃~-75.1℃ for the detecting CCD, The temperature control accuracy was 0.1℃. The thermal optical test showed that the defocus of the FGS was 4μm after focusing, which verified the thermal and structural design performance of the focal plane component. ? 2021 SPIEAccession Number: 20220911705522 -
Record 134 of
Title:A new friction compensation method for photoelectric platform
Author(s):Chang, Sansan(1); Gao, Bo(1); Zhang, Gaopeng(1); Bian, He(1)Source: Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) Volume: 52 Issue: 2 DOI: 10.11817/j.issn.1672-7207.2021.02.011 Published: February 26, 2021Abstract:To reduce the negative influence of this disturbance and improve the stability accuracy of photoelectric platform, a new compensation scheme based on friction model was proposed. Firstly, the process of friction rejection by the traditional method was analyzed, and the method of combining the encoder and gyroscope to estimate the speed at low speed was proposed and the friction model was improved by the method. At the same time, an extended state observer(ESO)was introduced to observe and compensate for the error caused by the difference between the system model and the compensation model. The problem of system friction characteristics drift with the environment and other factors in the work was solved. Finally, in order to verify the effectiveness of the method, the speed stability experiment was carried out on the three-axis swing table. The results show that the compensation effect of the near zero speedis is raised by improved friction model. Compared with the traditional method, the speed stability and the isolation degree increase by 67% and 58%, respectively, and the isolation degree can still be maintained when the friction model parameter perturbation is 10%, presentingstrong robustness. This method is easy to be realized in engineering and has a high practical value for compensating for the friction force of photoelectric platform to improve the stability accuracy. ? 2021, Central South University Press. All right reserved.Accession Number: 20211310148440 -
Record 135 of
Title:Modified snapshot spectroscopic ellipsometry based on optical frequency-domain interferometry
Author(s):Li, Siyuan(1,2); Zhang, Chunmin(3); Quan, Naicheng(1,4)Source: Optik Volume: 228 Issue: DOI: 10.1016/j.ijleo.2020.166165 Published: February 2021Abstract:We propose a modified snapshot spectroscopic ellipsometry based on optical frequency-domain interferometry. The proposed system employs only one high-order retarder and a Wollaston prism to analyze the changed state of polarization of the reflected light and can provide the maximum channel bandwidth of the channeled spectroscopic ellipsometry. The spectroscopic ellipsometric parameters of isotropic samples can be accurately measured in a measurement speed of 40 ms without mechanical or active modulation devices. The feasibility of the proposed spectroscopic ellipsometry is demonstrated by experiments. ? 2020Accession Number: 20210209744690 -
Record 136 of
Title:Bio-inspired representation learning for visual attention prediction
Author(s):Yuan, Yuan(1); Ning, Hailong(2,3); Lu, Xiaoqiang(2)Source: arXiv Volume: Issue: DOI: null Published: March 9, 2021Abstract:Visual Attention Prediction (VAP) is a significant and imperative issue in the field of computer vision. Most of existing VAP methods are based on deep learning. However, they do not fully take advantage of the low-level contrast features while generating the visual attention map. In this paper, a novel VAP method is proposed to generate visual attention map via bio-inspired representation learning. The bio-inspired representation learning combines both low-level contrast and high-level semantic features simultaneously, which are developed by the fact that human eye is sensitive to the patches with high contrast and objects with high semantics. The proposed method is composed of three main steps: 1) feature extraction, 2) bio-inspired representation learning and 3) visual attention map generation. Firstly, the high-level semantic feature is extracted from the refined VGG16, while the low-level contrast feature is extracted by the proposed contrast feature extraction block in a deep network. Secondly, during bio-inspired representation learning, both the extracted low-level contrast and high-level semantic features are combined by the designed densely connected block, which is proposed to concatenate various features scale by scale. Finally, the weighted-fusion layer is exploited to generate the ultimate visual attention map based on the obtained representations after bio-inspired representation learning. Extensive experiments are performed to demonstrate the effectiveness of the proposed method. ? 2021, CC BY.Accession Number: 20210073461 -
Record 137 of
Title:Attention-Based Multi-Branch Network for Low-Light Image Enhancement
Author(s):Jiao, Yin(1,2); Zheng, Xiangtao(2); Lu, Xiaoqiang(2)Source: 2021 IEEE 2nd International Conference on Big Data, Artificial Intelligence and Internet of Things Engineering, ICBAIE 2021 Volume: Issue: DOI: 10.1109/ICBAIE52039.2021.9389960 Published: March 26, 2021Abstract:Low-light conditions make the obtained images suffer a series of degradation, such as low contrast, noise interference and color distortion. Many previous learning-based methods have made remarkable progress, but they may still produce unsatisfactory results for ignoring noise in low-light regions. An attention-based multi-branch network is proposed, which can adequately enhance the image and suppress latent noise. The proposed method firstly estimates illumination component and reflectance component through a decomposition process. Then the illumination component is brightened to reconstruct the global lighting distribution, and the reflectance component is restored to remove noise and maintain details. A lightweight but effective attention block is employed to guide the restoration of the reflectance component, so as to concentrate on the distribution of lighting in different regions and effectively suppress noise in the dim environment. Extensive experiments on several datasets show the proposed method can achieve good results compared with classic and state-of-the-art methods. ? 2021 IEEE.Accession Number: 20211710245631 -
Record 138 of
Title:Super-resolution Imaging Lidar based on Fourier Ptychography
Author(s):Wang, Yuming(1,2); Zhao, Hui(1); Yang, Mingyang(1,2); Qu, Youshan(1); Fan, Xuewu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12075 Issue: DOI: 10.1117/12.2604172 Published: 2021Abstract:Traditional imaging lidar exhibits an obvious trade-off between the resolution and the size of its optical system. In order to realize a miniaturized super-resolution (SR) imaging lidar, Fourier ptychography (FP) has been introduced to break through the diffraction limit of the camera lens. FP, derived from synthetic aperture method, is capable of acquiring high resolution and large field-of-view reconstructed images without increasing the aperture size by capturing multiple images with diverse incident angles before computationally combining with phase retrieval algorithm. In this work, a SR imaging lidar system was proposed by using reflective-type FP, which mainly consists of a s-CMOS camera, a Nd:YAG laser, and a 2-D translation stage so as to achieve aperture scanning on the x and y axes. To validate this technique experimentally, a set of images of a positive USAF chrome-on-glass target were obtained for quantitative analysis, and an uneven 1 yuan nickel-on-steel RMB coin was used to simulate the applicability of the SR imaging lidar in practical applications. The observations show that the obtained images based on FP technique have an obvious improvement in resolution, contrast, and clarity. It is worth mentioning that the resolution of these reconstructed images is increased over 3 times in the experiment on the USAF target. Moreover, the images under different apertures were collected, processed and analyzed, which suggest the initial image quality has a non-negligible influence on the reconstructed results. This technique not only improves the performance of the imaging lidar while maintaining low costs, but also bring new vitality in remote image recognition and analysis. ? 2021 SPIEAccession Number: 20220911705515 -
Record 139 of
Title:Integral order photonic RF signal processors based on a soliton crystal micro-comb source
Author(s):Tan, Mengxi(1); Xu, Xingyuan(8); Wu, Jiayang(1); Corcoran, Bill(2); Boes, Andreas(3); Nguyen, Thach G.(3); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6,7); Mitchell, Arnan(3); Moss, David J.(1)Source: Journal of Optics (United Kingdom) Volume: 23 Issue: 12 DOI: 10.1088/2040-8986/ac2eab Published: December 2021Abstract:Soliton crystal micro-combs are powerful tools as sources of multiple wavelength channels for radio frequency (RF) signal processing. They offer a compact device footprint, a large number of wavelengths, very high versatility, and wide Nyquist bandwidths. Here, we demonstrate integral order RF signal processing functions based on a soliton crystal micro-comb, including a Hilbert transformer and first, second and third-order differentiators. We compare and contrast the results and the trade-offs involved with varying the comb spacing, and tap design and shaping methods. ? 2021 IOP Publishing LtdAccession Number: 20214811231833 -
Record 140 of
Title:Design of image-side telecentric off-axis three-mirror anastigmatic systems based on the coaxial parent mirrors
Author(s):Li, Xijie(1); Zou, Chunbo(1); Yang, Jiating(1)Source: Optik Volume: 241 Issue: DOI: 10.1016/j.ijleo.2021.166855 Published: September 2021Abstract:Image-side telecentric unobscured optical systems have significant application values in the field of space optics. However, off-axis astigmatism increases with an increase of field of view (FOV), relative aperture and image-side telecentricity, so it's very difficult to design image-side telecentric anastigmatic systems with an ultrawide FOV. To solve these issues, this paper proposes an effective method that is based on the coaxial parent mirrors. By calculating the off-axis aberration optical path of the primary mirror (PM), secondary mirror (SM) and tertiary mirror (TM), and introducing even aspheric surface and adding boundary constraints, a prospective system with a focal length of 400 mm, a relative aperture of 1/3, an FOV of 18° × 6°, and a telecentricity of greater than 0.5°is designed. The design results show that the modulation transfer function (MTF) of the system is greater than 0.7 at the Nyquist frequency of 34 lp/mm, which is close to the diffraction limitation. It has a high imaging quality, thereby proving the image-side telecentric off-axis three-mirror anastigmatic (TMA) system to be effective. ? 2021 Elsevier GmbHAccession Number: 20211910319136 -
Record 141 of
Title:Effective suppression of mode distortion induced by stimulated Raman scattering in high-power fiber amplifiers
Author(s):Gao, Wei(1,2,3); Fan, Wenhui(1,3,5); Ju, Pei(1,3); Li, Gang(1,3); Zhang, Yanpeng(2); He, Aifeng(4); Gao, Qi(1,3); Li, Zhe(1,3)Source: High Power Laser Science and Engineering Volume: 9 Issue: DOI: 10.1017/hpl.2021.13 Published: 2021Abstract:Mode distortion induced by stimulated Raman scattering (SRS) has become a new obstacle for the further development of high-power fiber lasers with high beam quality. Here, an approach for effective suppression of the SRS-induced mode distortion in high-power fiber amplifiers has been demonstrated experimentally by adjusting the seed power (output power of seed source) and forward feedback coefficient of the rear port in the seed source. It is shown that the threshold power of the SRS-induced mode distortion can be increased significantly by reducing the seed power or the forward feedback coefficient. Moreover, it has also been found that the threshold power is extremely sensitive to the forward feedback power value from the rear port. The influence of the seed power on the threshold power can be attributed to the fact that the seed power plays an important role in the effective length of the gain fiber in the amplifier. The influence of the forward feedback coefficient on the threshold power can be attributed to the enhanced SRS configuration because the end surface of the rear port together with the fiber in the amplifier constitutes a half-opening cavity. This suppression approach will be very helpful to further develop the high-power fiber amplifiers with high beam quality. ? The Author(s), 2021. Published by Cambridge University Press in association with Chinese Laser Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.Accession Number: 20214611156548 -
Record 142 of
Title:FPGA applied in hardware computer aided design of gigabit ethernet data acquisition system
Author(s):Hua, Wang(1); He, Bian(1); Hao, Wang(1); Lei, Yang(1)Source: Journal of Physics: Conference Series Volume: 2033 Issue: 1 DOI: 10.1088/1742-6596/2033/1/012079 Published: October 5, 2021Abstract:With the increasing popularity of the network, Ethernet has been widely used because of its wide distribution and convenient access. At the same time, due to the continuous innovation of Ethernet technology and the continuous development of new functions, it has gradually become the most popular network technology in the world. Gigabit Ethernet is a technology based on the Ethernet standard, and has become the mainstream because of its high efficiency, high speed and high performance Network technology. This paper presents a hardware design scheme of Gigabit Ethernet data acquisition system based on FPGA, including power module, clock module, FPGA main controller module, 88e1111 Ethernet module, which realizes data acquisition and transmission. The system is miniaturized, low-cost and portable. ? 2021 Institute of Physics Publishing. All rights reserved.Accession Number: 20214311059180 -
Record 143 of
Title:Wideband low-profile dual-polarized dielectric patch antenna with metallic pins
Author(s):Cao, Zhi-Xun(1); Zhang, Li(1); Wang, Hao(2); Lu, Hao(1); Liu, Jianfeng(1); Qiu, Yonghui(1)Source: Microwave and Optical Technology Letters Volume: 63 Issue: 12 DOI: 10.1002/mop.33036 Published: December 2021Abstract:In this article, a lowprofile dual-polarized dielectric patch antenna (DPA) using TM101 and TM121 modes is proposed for achieving the impedance bandwidth (BW) enhancement. By introducing four metallic pins in a dielectric patch resonator (DPR), the TM121 mode is shifted to low frequencies while TM101 mode is shifted to high frequencies. Therefore, the two modes can be close to each other for obtaining wide working bandwidth. Moreover, two orthogonal aperture-coupled feeders are employed to excite the proposed DPR to realize the dual polarization. Finally, the proposed antenna is fabricated and measured. The simulated and measured results show that the 10 dB impedance matching bandwidth is 15.2% (5.05–5.87 GHz), while maintaining the low-profile characteristics with the height of 0.07λ0 (λ0 is free space wavelength at the center frequency f0). In addition, the antenna achieved a peak gain of 8.55 dBi in the operating frequency. ? 2021 Wiley Periodicals LLC.Accession Number: 20213610857910 -
Record 144 of
Title:Comprehensive Evaluation Method of Job Satisfaction Based on Improved Analytic Hierarchy Process
Author(s):Dai, Nanru(1); Deng, Ren(1); Tang, Siyi(1); Zhang, Shanshan(1); Li, Xijie(2)Source: ACM International Conference Proceeding Series Volume: Issue: DOI: 10.1145/3474963.3474983 Published: June 25, 2021Abstract:Summer jobs have become an increasingly popular topic among high school students these days. They provide invaluable enrichment opportunities to make money and gain experience and skills. However, due to the outbreak of coronavirus, it is more challenging for high school students to identify the most appropriate summer jobs for them. We first identify related variables and collect data useful to our model. We consider 22 different summer jobs and consider variables including income, company size, risks, comfort, and skills to be gained. For the overall model, we adopt an Analytic Hierarchy Process to evaluate the weights or relative importance of each variable for each individual. Combining the weights we calculate from both models, we then obtain the overall weighting used for each individual. However, considering students usually want to have an array of open options to choose from, we utilize K-Means clustering rather than simply returning the one single "best"job. Then, the best cluster of job options is output to our user. In regards to the fictional characters, we develop 10 different characters that we believe are highly representative of the US high school student population. Application of our developed model onto these fictional characters indicates that our model is fairly effective in identifying the most appropriate summer jobs for students. ? 2021 ACM.Accession Number: 20214411086123