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Multi-path navigation method using solar panel-reflected solar oscillations for Earth satellites

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science China(Information sciences) 2024年第7期67卷 327-328页

作者： Yuqing YANG Haonan YANG Xiaolin NING Weiren WU Jiancheng FANG school of instrument science & opto-electronics engineering Beihang University Lunar Exploration and Space Program Center China National Space Administration

Several autonomous navigation methods have been studied to reduce reliance on the ground stations. Geomagnetic navigation, gravity gradient navigation, and celestial navigation using optical sensors are typical autonomous navigation methods. Geomagnetic and gravity gradient navigation have low navigation accuracy (1301 m [1] and 235 m [2], respectively) due to the poor accuracy of the geomagnetic and gravity gradient maps.

关键词： Solar panels

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Sawtooth-enhanced bend sensor for gesture recognition

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science China(Technological sciences) 2024年第6期67卷 1727-1736页

作者： BAI YanRu ZHANG ZiHang WANG HaoYu GUO Rui LI XiSheng school of Automation and Electrical engineering University of Science and Technology BeijingBeijing100083China school of Advanced engineering University of Science and Technology BeijingBeijing100083China school of Precision instrument and opto-electronics engineering Tianjin UniversityTianjin300072China school of Computer and Communication engineering University of Science and Technology BeijingBeijing100083China

Gesture recognition has diverse application prospects in the field of human-computer ***,gesture recognition devices based on strain sensors have achieved remarkable results,among which liquid metal materials have considerable advantages due to their high tensile strength and *** improve the detection sensitivity of liquid metal strain sensors,a sawtooth-enhanced bending sensor is proposed in this *** with the results from previous studies,the bending sensor shows enhanced resistance *** addition,combined with machine learning algorithms,a gesture recognition glove based on the sawtooth-enhanced bending sensor is also fabricated in this study,and various gestures are accurately *** the fields of human-computer interaction,wearable sensing,and medical health,the sawtooth-enhanced bending sensor shows great potential and can have wide application prospects.

关键词： liquid metal bending sensor gesture recognition machine learning

Picosecond gain-switched polymer fiber random lasers

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Chinese Optics Letters 2024年第4期22卷 20-25页

作者：杜文彧高森张小娟李思祺蒯雁王治强曹志刚徐峰刘宇徐林张俊喜谢康俞本立胡志家 Information Materials and Intelligent Sensing Laboratory of Anhui Province Key Laboratory of Opto-Electronic Information Acquisition and Manipulation of Ministry of EducationSchool of Physics and Opto-electronics EngineeringAnhui UniversityHefei 230601China school of instrument science and opto-electronics engineering Laboratory of Optical Fibers and Micro-nano PhotonicsHefei University of TechnologyHefei 230009China school of opto-electronic engineering Zaozhuang UniversityZaozhuang 277160China

Random lasers are a type of lasers that lack typical resonator structures,offering benefits such as easy integration,low cost,and low spatial *** features make them popular for speckle-free imaging and random number ***,due to their high threshold and phase instability,the production of picosecond random lasers has still been a *** this work,we have developed three dyes incorporating polymer optical fibers doped with various scattering nanoparticles to produce short-pulsed random fiber ***,stable picosecond random laser emission lasting600 ps is observed at a low pump energy of 50μJ,indicating the gain-switching *** inversion and gain undergo an abrupt surge as the intensity of the continuously pumped light nears the threshold *** the intensity of the continuously pumped light reaches a specific value,the number of inversion populations in the“scattering cavity”surpasses the threshold *** results based on a model that considers power-dependent gain saturation confirmed the above *** research helps expand the understanding of the dynamics behind random medium-stimulated emission in random lasers and opens up possibilities for mode locking in these systems.

关键词： random laser polymer optical fiber gain-switched laser picosecond pulse

Grating-free autofocus for single-pixel microscopic imaging

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Photonics Research 2024年第6期12卷 1313-1321页

作者： GUAN WANG HUAXIA DENG YU CAI MENGCHAO MA XIANG ZHONG XINGLONG GONG CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China school of instrument science and opto-electronics engineering Hefei University of TechnologyHefei 230009China

As a computational technology,single-pixel microscopic imaging(SPMI)transfers the target’s spatial information into a temporal *** traditional focusing method of imaging before evaluation is not applicable to the SPMI *** propose a grating-free autofocus strategy derived from the physical mechanism of optical *** the amplitude information of just one high-frequency point in the spectrum is all that is needed to achieve fast autofocus with the SPMI ***,only four patterns need to be cyclically projected,enabling efficient localization of the focal plane based on the measurement *** demonstrate SPMI autofocus experiments at micrometer and even nanometer depths of *** proposed method can be extended to achieve SMPI autofocus with invisible optical pattern illumination.

关键词： optical system. illumination

Polarization-entangled photon pairs with factorable spectra engineered by using an uneven four-stage nonlinear interferometer

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Chinese Optics Letters 2024年第5期22卷 106-110页

作者：崔亮陈浩然李嘉敏李小英 College of Precision instrument and opto-electronics engineering Key Laboratory of Opto-Electronics Information TechnologyMinistry of EducationTianjin UniversityTianjin 300072China school of Physics Taiyuan University of TechnologyTaiyuan 030000China

We report the generation of polarization-entangled photon pairs in the 1550 nm band by pumping an uneven nonlinear interferometer loop with two orthogonally polarized counterpropagating pump *** uneven nonlinear interferometer,providing a more ideal interference pattern due to the elimination of secondary maxima,consists of four pieces of dispersion-shifted fibers sandwiched with three pieces of standard single-mode fibers,and the lengths of the nonlinear fibers follow the binomial *** mode number of the photon pairs deduced from the measured joint spectrum is∼*** collection efficiency of the photon pairs is found to be∼94%(after background noise correction).The directly measured visibility of two-photon interference of the polarization-entangled photon pairs is∼92%,while no interference is observed in the direct detection of either the signal or idler photons.

关键词： polarization-entangled photon pairs nonlinear interferometer quantum state engineering optical fiber

Coherent terahertz wave emission from laser-induced plasma in isotropic transparent solid dielectrics

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Chinese Optics Letters 2024年第7期 126-130页

作者：陈宇轩何宇航戴辰殷喇向宇田震戴建明 Center for Terahertz Waves and school of Precision instrument and opto-electronics engineering Tianjin University

In this Letter, we employ fused silica and two types of optical glass as examples to investigate the coherent terahertz(THz)wave emission from laser-ionized isotropic transparent dielectrics. Based on the laser energy and incident angle dependences, we ascribe the THz emission to the ponderomotive force-induced dipole oscillation. Additionally, our investigation on the dependence of THz amplitude on the laser pulse duration confirms the dominant role of avalanche ionization in solid dielectrics. The THz emission can be utilized to indirectly monitor the ultrafast dynamics of carrier generation and motion during the laser ionization process of solid dielectrics.

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Prediction and Regulation of Delamination at Flexible Film/Finite-Thickness-Substrate Structure Interfaces

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Acta Mechanica Solida Sinica 2024年第2期37卷 238-251页

作者： Yutang Zhou Yunlong Xu Haoran Gong Chenyu Wang Department of engineering Mechanics Northwestern Polytechnical UniversityXi’an710072China school of instrumentation science and opto-electronics engineering Beihang UniversityBeijing100191China

Regulating the surface instability of thin film/substrate structures has been successfully applied to prepare new ductile electronic ***,such electronic devices need to be subjected to external loads during operation,which can easily induce delamination of the thin-film electronic device from the *** study aims to investigate the instability characteristics of hard films on flexible substrate surfaces from theoretical analysis and numerical simulation *** finite-thickness substrates,this paper establishes theoretical models for pure bending,bent wrinkle,partial delamination,and total delamination buckling of film/substrate structures based on the nonlinear Euler–Bernoulli beam theory and the principle of minimum energy;then the effects of material and geometric parameters of the structure,interfacial adhesion strength,and pre-strain on the evolutionary path of the four patterns are *** study results show that:the greater Young’s modulus of the substrate is,the larger the parameter region where partial delamination of the film/substrate structure occurs,and the smaller the parameter region where bent wrinkle *** varying Young’s modulus,thickness of the film and substrate,interfacial adhesion coefficient,and pre-strain,the buckling pattern of the structure can be predicted and *** parametric design intervals for each pattern are summarized in the phase *** results of this paper provide theoretical support for the design and reliability evaluation of flexible electronic devices.

关键词： Thin film/finite-thickness-substrate structure Delamination Surface instability Pattern evolution

A comprehensive analysis of DAC-SDC FPGA low power object detection challenge

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science China(Information sciences) 2024年第8期67卷 300-320页

作者： Jingwei ZHANG Guoqing LI Meng ZHANG Xinye CAO Yu ZHANG Xiang LI Ziyang CHEN Jun YANG school of electronics science and engineering Southeast University

The lower power object detection challenge(LPODC) at the IEEE/ACM Design Automation Conference is a premier contest in low-power object detection and algorithm(software)-hardware co-design for edge artificial intelligence, which has been a success in the past five years. LPODC focused on designing and implementing novel algorithms on the edge platform for object detection in images taken from unmanned aerial vehicles(UAVs), which attracted hundreds of teams from dozens of countries to participate. Our team SEUer has been participating in this competition for three consecutive years from 2020 to 2022 and obtained sixth place respectively in 2020 and 2021. Recently, we achieved the championship in 2022. In this paper, we presented the LPODC for UAV object detection from 2018 to 2022, including the dataset, hardware platform,and evaluation method. In addition, we also introduced and discussed the details of methods proposed by each year's top three teams from 2018 to 2022 in terms of network, accuracy, quantization method, hardware performance, and total score. Additionally, we conducted an in-depth analysis of the selected entries and results, along with summarizing representative methodologies. This analysis serves as a valuable practical resource for researchers and engineers in deploying the UAV application on edge platforms and enhancing its feasibility and reliability. According to the analysis and discussion, it becomes evident that the adoption of a hardware-algorithm co-design approach is paramount in the context of tiny machine learning(TinyML).This approach surpasses the mere optimization of software and hardware as separate entities, proving to be essential for achieving optimal performance and efficiency in TinyML applications.

关键词： algorithm-hardware co-design convolutional neural networks field programmable gate array low power object detection tiny machine learning

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Distributed Multicircular Circumnavigation Control for UAVs with Desired Angular Spacing

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Defence Technology（防务技术） 2024年第1期31卷 429-446页

作者： Shixiong Li Xingling Shao Wendong Zhang Qingzhen Zhang National Key Laboratory for Electronic Measurement Technology School of Instrument and ElectronicsNorth University of ChinaTaiyuan 030051China school of Automation science and Electrical engineering Beihang UniversityBeijing 100086China

This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary *** defining a coordinated error relative to neighboring angular spacing,under the premise that target information is perfectly accessible by all nodes,a centralized circular enclosing control strategy is derived for multiple UAVs connected by an undirected graph to allow for formation behaviors concerning the moving ***,to avoid the requirement of target’s states being accessible for each UAV,fixed-time distributed observers are introduced to acquire the state estimates in a fixed-time sense,and the upper boundary of settling time can be determined offline irrespective of initial properties,greatly releasing the burdensome communication ***,with the aid of fixed-time distributed observers,a distributed circular circumnavigation controller is derived to force all UAVs to collaboratively evolve along the preset circles while keeping a desired angular *** is inferred from Lyapunov stability that all errors are demonstrated to be *** are offered to verify the utility of proposed protocol.

关键词： Angular spacing Distributed observer Multicircular circumnavigation Moving target UAVs