2020
2020
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Record 229 of
Title:A Method for Evaluating Medium and High-earth Orbit Object Telescope's Precision by Beidou's Precise Ephemeris
Author(s):Lu, Chang-Ming(1,2,3); Gao, Xin(2); Li, Xi-Yu(2); Xie, Mei-Lin(1); Li, Zhi-Guo(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 49 Issue: 10 DOI: 10.3788/gzxb20204910.1012001 Published: October 1, 2020Abstract:In order to solve the lacking of calibration means when working in the field, the Beidou Navigation Satellite System(BDS) is used to evaluate telescopes' astronomy and axis orientation precision, which survey the Medium And High Earth Orbit Objects(MHEO). This research is dedicated to deduce the principle of astronomy and axis orientation, and testify the feasibility of evaluating the electro-optical telescope's accuracy with BDS by analysising the satellites' coverage, orbit pricision and brightness, which has big diameter. Firstly, we interpolate the regular BDS precise ephemeris by Lagrange polynomial, whose data interval is 5 minutes. With coordinate conversion, we get the apparent ascension and apparent declination in the agreement celestial coordinate system, azimuth and pitch in the station coordinate system, which are the true value for astronomy and axis orientation precision evaluation. A MHEO telescope's astronomy orientation precision is superior to 2″ and axis orientation precision is superior to 7″ by this method. ? 2020, Science Press. All right reserved.Accession Number: 20204509448075 -
Record 230 of
Title:Broadband Photonic RF Channelizer with 92 Channels Based on a Soliton Crystal Microcomb
Author(s):Xu, Xingyuan(1,2); Tan, Mengxi(1); Wu, Jiayang(1); 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 Lightwave Technology Volume: 38 Issue: 18 DOI: 10.1109/JLT.2020.2997699 Published: September 15, 2020Abstract:We report a broadband radio frequency (RF) channelizer with up to 92 channels using a coherent microcomb source. A soliton crystal microcomb, generated by a 49 GHz micro-ring resonator (MRR), is used as a multi-wavelength source. Due to its ultra-low comb spacing, up to 92 wavelengths are available in the C band, yielding a broad operation bandwidth. Another high-Q MRR is employed as a passive optical periodic filter to slice the RF spectrum with a high resolution of 121.4 MHz. We experimentally achieve an instantaneous RF operation bandwidth of 8.08 GHz and verify RF channelization up to 17.55 GHz via thermal tuning. Our approach is a significant step towards the monolithically integrated photonic RF receivers with reduced complexity, size, and unprecedented performance, which is important for wide RF applications ranging from broadband analog signal processing to digital-compatible signal detection. ? 1983-2012 IEEE.Accession Number: 20203809187327 -
Record 231 of
Title:Using hyperspectral imaging automatic classification of gastric cancer grading with a shallow residual network
Author(s):Liu, Song(1,2); Wang, Quan(1,3); Zhang, Geng(1); Du, Jian(1); Hu, Bingliang(1,3); Zhang, Zhoufeng(1,3)Source: Analytical Methods Volume: 12 Issue: 30 DOI: 10.1039/d0ay01023e Published: August 14, 2020Abstract:The gastric cancer grading of patients determines their clinical treatment plan. We use hyperspectral imaging (HSI) gastric cancer section data to automatically classify the three different cancer grades (low grade, intermediate grade, and high grade) and healthy tissue. This paper proposed the use of HSI data combined with a shallow residual network (SR-Net) as the classifier. We collected hyperspectral data from gastric sections of 30 participants, with the wavelength range of hyperspectral data being 374 nm to 990 nm. We compared the classification results between hyperspectral data and color images. The results show that using hyperspectral data and a SR-Net an average classification accuracy of 91.44% could be achieved, which is 13.87% higher than that of the color image. In addition, we applied a modified SR-Net incorporated direct down-sampling, asymmetric filters, and global average pooling to reduce the parameters and floating-point operations. Compared with the regular residual network with the same number of blocks, the floating-point operations of a SR-Net are one order of magnitude less. The experimental results show that hyperspectral data with a SR-Net can achieve cutting-edge performance with minimum computational cost and therefore have potential in the study of gastric cancer grading. This journal is ? The Royal Society of Chemistry.Accession Number: 20204609491413 -
Record 232 of
Title:Deep discrete hashing with pairwise correlation learning
Author(s):Chen, Yaxiong(1,2); Lu, Xiaoqiang(1)Source: Neurocomputing Volume: 385 Issue: DOI: 10.1016/j.neucom.2019.12.078 Published: 14 April 2020Abstract:Hashing technology plays an important role in large-scale visual search due to its low memory and fast retrieval speed. Most existing deep hashing approaches first leverage the continuous relaxation strategy to learn continuous approximate codes, and then transform them into discrete hash codes by separating quantization operations, which results in the suboptimal problem of hash codes and ultimately affects the performance of image retrieval. To solve this problem, we propose a novel deep discrete hashing approach with pairwise labels, namely Pairwise Correlation Discrete Hashing (PCDH), to leverage the pairwise correlation of deep features and semantic supervised information to directly guide discrete hashing codes learning. Firstly, we integrate discrete hash code learning and deep features learning in a unified network framework, which can utilize the semantic supervision to guide discrete hash codes learning. Secondly, we design a novel pairwise correlation constraint to perform pairwise correlation learning of deep features. Thirdly, we develop a novel pairwise construction module to mine good pairwise samples for discrete hash codes learning. Extensive experimental results show that the proposed PCDH approach achieves superior performance over other recent state-of-the-art hashing approaches. ? 2019 Elsevier B.V.Accession Number: 20200207985490 -
Record 233 of
Title:Restoration of Sparse Multispectral Single Photon Lidar Data
Author(s):Chen, Songmao(1,2); Hao, Wei(1); Su, Xiuqin(1); Zhang, Zhenyang(1,2); Wang, Shuchao(1,2); Zhu, Wenhua(1,2)Source: ICSPCC 2020 - IEEE International Conference on Signal Processing, Communications and Computing, Proceedings Volume: Issue: DOI: 10.1109/ICSPCC50002.2020.9259491 Published: August 21, 2020Abstract:This paper presents a new algorithm to restore the sparse multispectral data acquired by single photon LiDAR. Regarding to its sparsity, the robustness of depth estimation is improved by exploiting the correlations between wavelengths and multi-scale information. Furthermore, the non-local spatial correlations between pixels/patches are learned by the affinity graph and used as prior information to prompt the smoothness for both depth and reflectivity images. To reduce the computational cost, a non-uniform sampling algorithm and clustering strategy are adopted, where flexible sampling points were assigned to reduce the size of the graph while minimizing the loss in details and different spatial clusters can be processed in parallel. Finally, the restoration was achieved by optimizing a cost function which account for both multi-scale information and non-local spatial correlations. The cost function is efficiently solved by ADMM algorithm that present fast convergence. Results on simulated data showed the benefits of the proposed algorithm by comparing with state-of-the-art algorithms, and the fast computation justified the supreme performance. ? 2020 IEEE.Accession Number: 20205209674684 -
Record 234 of
Title:Spectral Clustering by Joint Spectral Embedding and Spectral Rotation
Author(s):Pang, Yanwei(1); Xie, Jin(1); Nie, Feiping(2); Li, Xuelong(3)Source: IEEE Transactions on Cybernetics Volume: 50 Issue: 1 DOI: 10.1109/TCYB.2018.2868742 Published: January 2020Abstract:Spectral clustering is an important clustering method widely used for pattern recognition and image segmentation. Classical spectral clustering algorithms consist of two separate stages: 1) solving a relaxed continuous optimization problem to obtain a real matrix followed by 2) applying K-means or spectral rotation to round the real matrix (i.e., continuous clustering result) into a binary matrix called the cluster indicator matrix. Such a separate scheme is not guaranteed to achieve jointly optimal result because of the loss of useful information. To obtain a better clustering result, in this paper, we propose a joint model to simultaneously compute the optimal real matrix and binary matrix. The existing joint model adopts an orthonormal real matrix to approximate the orthogonal but nonorthonormal cluster indicator matrix. It is noted that only in a very special case (i.e., all clusters have the same number of samples), the cluster indicator matrix is an orthonormal matrix multiplied by a real number. The error of approximating a nonorthonormal matrix is inevitably large. To overcome the drawback, we propose replacing the nonorthonormal cluster indicator matrix with a scaled cluster indicator matrix which is an orthonormal matrix. Our method is capable of obtaining better performance because it is easy to minimize the difference between two orthonormal matrices. Experimental results on benchmark datasets demonstrate the effectiveness of the proposed method (called JSESR). ? 2018 IEEE.Accession Number: 20184105927717 -
Record 235 of
Title:Tuning optical force of dielectric/metal core-shell placed above Au film
Author(s):Zhang, Jia-chen(1); Yu, Wei-xing(2); Xiao, Fa-jun(1); Zhao, Jian-lin(2)Source: Wuli Xuebao/Acta Physica Sinica Volume: 69 Issue: 18 DOI: 10.7498/aps.69.20200214 Published: September 20, 2020Abstract:Manipulating the core-shell structure with the optical force has been extensively studied, giving birth to applications such as particle sorting, biomarkers and drug delivery. Tailoring the optical force exerted on the core-shell above the metallic film remains unexplored, despite the obvious benefits for both fundamental research and applications including strong coupling, surface enhanced spectroscopy, nanolaser, and nanoscale sensing. In this work, we systematically investigate the optical force exerted on a dielectric/metal core-shell above a gold film by utilizing the Maxwell stress tensor formalism. It is found that at the present gold substrate, the optical force on the core-shell can be one order of magnitude larger than that on the individual core-shell due to the strong coupling between the core-shell and the gold film. Interestingly, the direction of the optical force can be reversed from positive to negative by distributing the local field from the upside of core-shell to the structure gap through changing the excitation wavelength. Furthermore, we demonstrate that the magnitude and peak wavelength of the optical force can be well controlled by altering the structure gap, the size and refractive index of the core. More specifically, it is found that the coupling strength between the core-shell and the gold film decreases with the gap size increasing. As a result, we observe the blue shift of bonding mode and the decrease of local field in the gap, which leads the force peak wavelength to be blue-shifted and the force peak magnitude to decrease, respectively. Also, by increasing the radius and refractive index of the core, a red shift of force peak is accompanied with the red shift of the bonding mode. In addition, the force peak magnitude follows the same trend as the total local field enhancement factor when the radius and refractive index of the core change. We hope that our results open the way to control the cavity size of particle on film structure, which would be beneficial for tailoring the light matter interaction even down to single molecular level and promises to have the applications in novel functional photonic devices. ? 2020 Chinese Physical Society.Accession Number: 20204109320029 -
Record 236 of
Title:Improved RT-MDNet for panoramic video target tracking
Author(s):Wang, Dianwei(1); Fang, Haoyu(1); Liu, Ying(1); Wu, Shiqian(2); Xie, Yongjun(3); Song, Haijun(3)Source: Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology Volume: 52 Issue: 10 DOI: 10.11918/201910175 Published: October 30, 2020Abstract:In the process of panoramic video target tracking, the target deformation and scale changes caused by light change, interference of similar background, and object moving may result in target drift or missing, leading to low success rate and poor robustness. To address these issues, a target tracking method based on long short-term memory (LSTM) network and improved Real-Time MDNet (RT-MDNet) network was proposed. First, shallow convolution neural network was utilized to extract features, and adaptive RoIAlign was adopted to reduce pixel loss in the convolution process. Then, the weight of the last layer of the full connection layers was updated online by utilizing the target features to achieve foreground background separation and extract the target area. Lastly, the scale of the target box was selected adaptively by means of LSTM, and the target position information was thus obtained. Experimental results show that monocular vision algorithm could hardly adapt to the scale change and background change when applied in panoramic dataset, while the proposed method that utilizes 3-layer LSTM network to construct scale prediction module could effectively solve these problems. The algorithm can efficiently deal with the situations of small target, target occlusion, and cross motion of multiple targets in target tracking while maintaining accuracy, achieving better visual effect and higher overlap rate score. Copyright ?2020 Journal of Harbin Institute of Technology.All rights reserved.Accession Number: 20204109337590 -
Record 237 of
Title:A data encryption and fast transmission algorithm based on surveillance video
Author(s):Qiu, Shi(1); Cui, Ying(2); Meng, Xianjia(3)Source: Wireless Communications and Mobile Computing Volume: 2020 Issue: DOI: 10.1155/2020/8842412 Published: 2020Abstract:Video surveillance is an effective way to record current events. In view of the difficulty of efficient transmission of massive surveillance video and the risk of leakage in the transmission process, a new data encryption and fast transmission algorithm is proposed in this paper. From the perspective of events, the constraints of time and space dimension is broken. First, a background and moving object extraction model is built based on video composition. Then, a strong correlation data encryption and fast transmission model is constructed to achieve efficient data compression. Finally, a data mapping mechanism is established to realize the decoding of surveillance video. Our experimental results show that the compression ratio of the proposed algorithm is more than 60% under the premise of image confidentiality. ? 2020 Shi Qiu et al.Accession Number: 20203509099830 -
Record 238 of
Title:Reflection grating spectrometer based on AOTF
Author(s):Tang, Qian(1); Zhang, Guo Qing(1); Zhang, Chun Min(1); Zhao, Bao Chang(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11455 Issue: DOI: 10.1117/12.2565203 Published: 2020Abstract:As for detecting the atmosphere, a spectrometer includes five sub-spectrometers (two UV spectrometers, one VIS/IR spectrometer and two SWIR spectrometers) covering 240-2400nm is proposed. The spectrometer will be operated at height of 400km in three viewing modes (Limb, Occultation and Nadir). The spatial resolution is better than 100km2 in the three modes. This article introduces one of the five sub-spectrometers which is based on AOTF (AOTF: Acoustic-Optic Tunable Filter) and working in 1500-2400nm. This scheme utilizes AOTF to select different spectral ranges with 80cm-1 wave number, and then realizes the resolution of 0.1nm (λ/Δλ >105) by a reflection grating. Instead of the parabolic reflector, a transmission light group is selected. The detail design indexes are given and stimulated by Zemax. ? 2020 SPIE.Accession Number: 20203709173586 -
Record 239 of
Title:Research on a Method of Two Aircraft Intersection Measurement Based on INS/ CNS Integrated Navigation
Author(s):Meilin, Xie(1,4); Yu, Cao(1,2,3,4); Wei, Hao(1,4); Wei, Huang(1,4); Xuezheng, Lian(1,4); Kai, Liu(1,4); Feng, Jing(1,3,4); Peng, Liu(1,3,4); Xubin, Feng(1,3,4)Source: 2020 IEEE 3rd International Conference on Electronics Technology, ICET 2020 Volume: Issue: DOI: 10.1109/ICET49382.2020.9119573 Published: May 2020Abstract:The target position accuracy of the two aircraft intersection position system depends heavily on the position and attitude measurement accuracy of the platform. For this reason, this paper proposes the INS/ CNS integrated navigation method based on the stable platform of star seeking for the intersection measurement environment of airborne photoelectric platform, which is used to obtain the attitude and position reference of UAV platform accurately and in real time, finally improve the target position accuracy of the intersection measurement of two UAVs[3]. ? 2020 IEEE.Accession Number: 20202808913774 -
Record 240 of
Title:Non-linear calibration optimisation based on the Levenberg–Marquardt algorithm
Author(s):Hu, Guoliang(1,2); Zhou, Zuofeng(1); Cao, Jianzhong(1); Huang, Huimin(1,2)Source: IET Image Processing Volume: 14 Issue: 7 DOI: 10.1049/iet-ipr.2019.1489 Published: May 29, 2020Abstract:An outstanding calibration algorithm is the most important factor that affects the precision of attitude measurement. This study proposes a non-linear optimisation algorithm to refine the solutions of the initial guess obtained using the Zhang's technique, the Bouget's technique, or the Hartley's algorithm. Large sets of point correspondences were adopted to test the validity of the proposed method. Extensive practical experiments demonstrated that the proposed method can significantly improve the accuracy of calibration and ultimately obtains higher measurement precision. The error of the reprojection in the proposed method was ? The Institution of Engineering and Technology 2020.Accession Number: 20202108697744