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Nano-optoelectronics and Micro/Nano-photonics X 2024

作者： Chen, Ke Li, Dandan Liu, Ziyang Yang, Chenyi Lu, Bingheng Yang, Yadong Wang, Qianqian School of Optics and Photonics Beijing Institute of Technology Beijing100081 China National Key Laboratory on Near-surface Detection Beijing10072 China Key Laboratory of Photonic Information Technology Ministry of Industry and Information Technology Beijing100081 China

ISBN: (纸本)9781510682160

Dielectric laser accelerators (DLAs) can achieve acceleration gradients that are 1 to 2 orders of magnitude higher than traditional radiofrequency (RF) accelerators. Due to the micrometer-scale dimensions of the DLA acceleration structure, on the one hand, high requirements are imposed on the quality of the electron beam and the alignment among the electron beam, driving laser, and DLA in experiments. On the other hand, although the DLA acceleration gradient is very high, the acceleration distance is insufficient, resulting in relatively small absolute energy gain for sub-relativistic electrons after DLA acceleration. These electrons are susceptible to interference from stray electromagnetic fields during propagation, posing significant challenges to the resolution and accuracy of sub-relativistic electron energy spectrum testing. Based on the principle of laser-driven grating-structure DLA for accelerating electron beams, this paper designs a complete test system, constructs electronic dynamics simulation models and magnetic field measurement electron energy spectrum simulation models for verification, designs a double-layer magnetic shunt to shield the interference of leakage magnetic fields on electrons in the simulation, considers factors such as the beam spot radius, divergence angle, and geomagnetic field intensity of the electron beam that conform to experimental conditions, and finally obtains simulated images of electron spots on the fluorescent screen after the electron beam is deflected by the magnetic field. The electron dynamics simulation results show that the electron beam achieves a maximum energy gain of 14.4401 keV over an acceleration length of 36 μm, with an acceleration gradient reaching 401.114 MeV/m. Based on the acceleration effect, a magnetic field of BB = 170 Gs is set, and an electron spot after deflection is obtained. The edges of the spots before and after acceleration are separated by Δd = 4.2889 mm, and the maximum energy gain measurem

关键词： Fluorescent screens

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A Practical Control Strategy for Magnetic Levitation System against Two Probes Failures

A Practical Control Strategy for Magnetic Levitation System ...

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第三十九届中国控制会议

作者： Jinhui Li Kai Ding Jianmei Sun Chi Wang Hongtao Zhao Huijie Zhu Science and Technology on Near-Surface Detection Laboratory Department of Precision Mechanical Engineering Shanghai University

This paper addresses the active control for magnetic levitation system against two probes failures, which degrades the stability of the levitation control, decreases the ride comfort near the rail joint. Firstly, a minimum interaction model containing vertical dynamics of electromagnets, cabin and traditional control scheme is developed. The output characteristics of probes near or under the typical joint are obtained by fitting experimental data. It shows that the maximum of the deviation values is up to11 mm, which should be attenuated effectively. Inspired by the probes' output characteristics and limited response range in the process of crossing the joint, a practical joint recognition method is explored. It shows that the joint can be identified *** a pair of complementary filters acting on acceleration and limited gap signal is developed to reconstruct the levitation gap signals. It shows that the deviations of the synthesized value are reduced substantially. After building the overall dynamic model with details, numerical simulations are carried out, and the results illustrating the improvement of stability and extended low speed range are provided.

关键词： maglev levitation control probes failures joint

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Ship Tracking with Static Electric Field Based on Adaptive Progressive Update Extended Kalman Filter

Ship Tracking with Static Electric Field Based on Adaptive P...

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2018 2nd International Conference on Electronic Information technology and Computer Engineering (EITCE 2018)

作者： Shouwei HU Bing YAN Science and Technology on Near-Surface Detection Laboratory College of Weapon Engineering Naval University of Engineering

An adaptive progressive update extended Kalman filter is introduced for unknown noise in ship tracking using static electric field. The corresponding state space model is established;the algorithm is introduced, and the simulation is designed. The simulation results show that the adaptive algorithm can effectively improve the performance of the algorithm, when the noise covariance deviates from the real value;the finite number of noise covariance estimation is beneficial to the stability of the filter.

关键词： filter Ship Tracking with Static Electric Field Based on Adaptive Progressive Update Extended Kalman Filter Kalman

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3D object tracking with transformer

arXiv

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arXiv 2021年

作者： Cui, Yubo Fang, Zheng Shan, Jiayao Gu, Zuoxu Zhou, Sifan Northeastern University Shenyang China Science and Technology on Near-Surface Detection Laboratory Wuxi China

Feature fusion and similarity computation are two core problems in 3D object tracking, especially for object tracking using sparse and disordered point clouds. Feature fusion could make similarity computing more efficient by including target object information. However, most existing LiDAR-based approaches directly use the extracted point cloud feature to compute similarity while ignoring the attention changes of object regions during tracking. In this paper, we propose a feature fusion network based on transformer architecture. Benefiting from the self-attention mechanism, the transformer encoder captures the inter- and intra- relations among different regions of the point cloud. By using cross-attention, the transformer decoder fuses features and includes more target cues into the current point cloud feature to compute the region attentions, which makes the similarity computing more efficient. Based on this feature fusion network, we propose an end-to-end point cloud object tracking framework, a simple yet effective method for 3D object tracking using point clouds. Comprehensive experimental results on the KITTI dataset show that our method achieves new state-of-the-art performance. Code is available at: https://***/3bobo/lttr. © 2021, CC BY.

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Semantic Segmentation for Evaluation of Defects on Smartphone Screens 5th

Semantic Segmentation for Evaluation of Defects on Smartphon...

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5th International Conference on Cognitive Systems and Signal Processing, ICCSIP 2020

作者： Zhu, Huijie Shen, Zhuohao Yuan, Shenggui Chen, Fuliang Li, Jinhui Science and Technology on Near-Surface Detection Laboratory Wuxi214035 China Department of Automation Shanghai Jiao Tong University Shanghai200240 China School of Software Engineering Shanghai Jiao Tong University Shanghai200240 China

ISBN: (纸本)9789811623356

Smartphone recycling is a heated topic recently because of environmental and economical concerns. However, the limited recognition ability of naked eyes to find defects on phones impedes further growth of the second-hand markets. Related work for this problem focuses on detection and feature extraction, which can be tough because of the thin shapes of the defects and similar characteristics obstructing discrimination between scratches and cracks. In this paper, we propose an algorithm using semantic segmentation based on HRNet to build an effective model to evaluate defects of screens quickly and precisely. We improve the performance of the model by introducing the Lovász-Softmax loss function and data augmentation. Peripheral methods including subdivision and postprocessing are proposed to reduce misprediction on small scratches and enforce reliability in practice. We compare our model with other networks on mIoU and Kappa scores, concluding on an empirical basis. © 2021, Springer Nature Singapore Pte Ltd.

关键词： Semantic Segmentation

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Priority Based Adaptive MAC Protocol for UAV Ad Hoc Networks 7

Priority Based Adaptive MAC Protocol for UAV Ad Hoc Networks

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7th International Conference on Computer and Communications, ICCC 2021

作者： Mou, Xinglin Li, Hao Yan, Feng Ding, Kai Wu, Tao Xia, Weiwei Shen, Lianfeng Southeast University National Mobile Communications Research Laboratory Nanjing210096 China Science and Technology On Near-Surface Detection Laboratory Wuxi214035 China Jiangsu ZhongLi Electronic Information Sci-Tech Co. Ltd Changshu215542 China

ISBN: (纸本)9781665409506

In this paper, a priority based adaptive MAC protocol (PM-MAC) is proposed for UAV ad hoc networks. Firstly, in the protocol, the arriving packets are classified into different queues according to the priority of services. A Markov chain model is proposed to analyze the channel access probabilities of different queues. and it is ensured that packets with high priority can access the channel with high probability. Secondly, the size of contention window is adaptively adjusted based on backoff times and the current packet size. Finally, simulation results show that PM-MAC can guarantee the access requirements of high priority packets, and compared with the traditional backoff method, the backoff mechanism in PM-MAC achieves better performance in access success rate, channel utilization and backoff delay. © 2021 IEEE.

关键词： Unmanned aerial vehicles (UAV)

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UWB SAR image segmentation algorithm based on polynomial analysis of statistical distribution

UWB SAR image segmentation algorithm based on polynomial ana...

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Asian and Pacific Conference on Synthetic Aperture Radar (APSAR)

作者： Wang Yuming Jin Tian Luo Chaopeng College of Information Science and Engineering Hunan Provincial Key Laboratory of Intelligent Computhing and Language Information Processing Science and Technology on Near-Surface Detection Laboratory Hunan Normal University Changsha R.P.China College of Electronic Science and Technology Science and Technology on Near-Surface Detection Laboratory National University of Defense Technology Changsha R.P.China Science and Technology on Near-Surface Detection Laboratory Wuxi China

ISBN: (数字)9781728129129

ISBN: (纸本)9781728129136

Aimed at the segmentation problem of ultrawideband synthetic aperture radar (UWB SAR) image, a novel algorithm based on polynomial analysis of statistical distribution is proposed in this letter. Firstly, we estimate the probability density function (PDF) for each pixel via sparse decomposition of which the dictionary consists of orthogonal polynomials (OP). Secondly, the weighting coefficients of corresponding OP are used to segment image using their maximum value. The experimental results validate the efficiency of this algorithm.

关键词： Image segmentation Probability density function Synthetic aperture radar Radar polarimetry Signal processing algorithms Scattering Statistical distributions

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Generative Adversarial Networks for Exo-atmospheric Infrared Objects Discrimination

Generative Adversarial Networks for Exo-atmospheric Infrared...

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Signal, Information and Data Processing (ICSIDP), IEEE International Conference on

作者： Dongya Wu Huanzhang Lu Huamin Tao Bendong Zhao Ming Zhao National University of Defense Technology Changsha China Science and Technology on Near-Surface Detection Laboratory Wuxi China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

External atmospheric infrared (IR) target recognition is an important research topic of space surveillance systems. The different micromotion states of the target result in respective features in the obtained sequence of IR radiation intensities, and such differences are difficult to visually describe and difficult to extract efficiently. Due to the difficulty of spatial experiments, the target sample data is very limited. In the case of limited labeled samples, there are few methods that can effectively classify time series effectively, resulting in low classification accuracy and difficulty in meeting practical application requirements. We use generative adversarial networks(GAN) for semi-supervised learning, combining neural network classifiers with adversarial generation models for the classification of infrared grayscale time series of spatial targets. The effective classification of the target is achieved with a small number of labeled target samples. The experiment proves the effectiveness of the method and the classification effect is better than other methods.

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Method for Detecting Multi-Modal Vibration Characteristics of Landmines

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Instrumentation 2018年第4期5卷 39-45页

作者： WANG Chi DUAN Naiyuan WU Zhiqiang MA Hui ZHU Jun Dept.of Precision Mechanical Engineering Shanghai UniversityShanghai 200072 Key Science and Technology on Near-surface Detection Laboratory Wuxi 214035

The acoustic vibration characteristics of landmines are investigated by means of modal analysis. According to the mechanical structure of landmines, a certain number of points are marked on the landmine shell to analyze its multi-modal vibration characteristics, based on laser self-mixing interferometer and taking 69 plastic landmine as an example, the vibration detection experiment system is built to show the results of analytical method of multi-modal testing. The first and second order natural frequencies of the bricks are 38 HZ and 106 HZ, 112 HZ and 232 HZ for plastic landmines, and 74 HZ and 290 HZ for metal landmines. The first and second order natural frequencies of the bricks are far smaller than those of plastic landmines and metal landmines. This indicates that landmines show multi-modal vibration characteristics under external excitation, which are significantly different from those of bricks. The findings can be used for further research on acoustic landmines detection technology.

关键词： Multi-Modal Vibration Natural Frequency Vibration Mode Acoustic Landmines detection

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Wavelet Packet Energy Entropy Based Feature Analysis of Seismic Signals from Vehicle Targets 5th

Wavelet Packet Energy Entropy Based Feature Analysis of Seis...

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5th International Conference on Intelligent Computing, Communication and Devices, ICCD 2019

作者： Ding, Kai Li, Xinghua Li, Hao Ma, Huayuan Fan, Lei Qi, Xiaogang Science and Technology on Near-Surface Detection Laboratory The First Scientific Research Institute of Wuxi Wuxi214035 China Army Engineering University of PLA Nanjing210007 China School of Mathematics and Statistics Xidian University Xi’an710071 China

ISBN: (纸本)9789811558863

The seismic signals of two typical types of vehicle targets—wheeled vehicles and tracked ones—were collected in field test, and decomposed at multiple levels using wavelet packet transformation (WPT), which has a multiresolution feature, to obtain detailed energy distribution. A method for computing the energy entropy of the seismic signals from a vehicle target was derived on the concept of information entropy based on probability statistics. The energy entropies of the seismic signals from the two types of vehicles were then analyzed, and the results indicate that the energy entropy reflects the seismic signals of different types of vehicles: the energy entropies of the seismic signals of the wheeled vehicles were greater than that of the tracked vehicles. In conclusion, this paper proposes to use the energy entropy as a new characteristic quantity of seismic signals from vehicle targets for feature extraction, which may pave a new way for identification of seismic signals from different vehicles. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Feature extraction

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