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Gigahertz frequency hopping in an optical phase-locked loop for Raman lasers

Chinese Physics B 2024年第2期33卷 60-65页

作者：毛德凯税鸿冕殷国玲彭鹏王春唯周小计 State Key Laboratory of Advanced Optical Communication System and Network School of ElectronicsPeking UniversityBeijing 100871China Institute of Carbon-based Thin Film Electronics Peking UniversityTaiyuan 030012China State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006China Institute of Advanced Functional Materials and Devices Shanxi UniversityTaiyuan 030031China

Raman lasers are essential in atomic physics,and the development of portable devices has posed requirements for time-division multiplexing of Raman *** demonstrate an innovative gigahertz frequency hopping approach of a slave Raman laser within an optical phase-locked loop(OPLL),which finds practical application in an atomic gravimeter,where the OPLL frequently switches between near-resonance lasers and significantly detuned Raman *** method merges the advantages of rapid and extensive frequency hopping with the OPLL’s inherent low phase noise,and exhibits a versatile range of applications in compact laser systems,promising advancements in portable instruments.

关键词： Raman lasers optical phase-locked loop frequency hopping

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Optical Multipath Interference Noise Resistant Digital RoF Fronthaul Achieving 15-dB SNR Enhancement Based on Uneven Spacing and Bit Interleaving

Optical Multipath Interference Noise Resistant Digital RoF F...

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2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023

作者： Hu, Yimin Zhu, Yixiao Zhang, Yikun Yan, Zijun Lin, Gengming Cheng, Ziyu Hu, Weisheng State Key Laboratory of Advanced Optical Communication System and Networks Shanghai Jiao Tong University Shanghai China

We demonstrate uneven spacing and bit interleaving schemes to suppress MPI impairment in digital radio-over-fiber system without complicated DSP by protecting the significant quantization bits. Both simulation/experim... 详细信息

ISBN: (纸本)9798350312614

关键词： bit interleaving digital radio-over-fiber multipath interference pulse amplitude modulation uneven spacing

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Biodegradation,hemocompatibility and covalent bonding mechanism of electrografting polyethylacrylate coating on Mg alloy for cardiovascular stent

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Journal of Materials Science & Technology 2020年第11期42卷 114-126页

作者： Yong-Xin Yang Zhe Fang Yi-Hao Liu Ya-Chen Hou Li-Guo Wang Yi-Fan Zhou Shi-Jie Zhu Rong-Chang Zeng Yu-Feng Zheng Shao-Kang Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou450001China Henan Key Laboratory of Advanced Magnesium Alloys Zhengzhou450002China Key Laboratory of Advanced Materials Processing&Mold Ministry of Education Zhengzhou450002China Corrosion Laboratory of Light Metals College of Material Science and EngineeringShandong University of Science and TechnologyQingdao266590China State Key Laboratory for Turbulence and Complex System and Department of Materials Science and Engineering College of EngineeringPeking UniversityBeijing100871China

Organic coatings are the most widely employed approach for the promotion of corrosion resistance of magnesium(Mg)***,traditional organic coatings are weakly bonded to Mg substrates due to physical ***,a polyethylacrylate(PEA)coating was fabricated on Mg-Zn-YNd alloy via *** surface structure and chemical composition were characterized by means of scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS),atomic force microscope(AFM)and Fourier transform infrared(FTIR)as well as time of flight-secondary ion mass spectrometer(To F-SIMS).The results showed that the surface roughness of PEA coating was dominated by scan rate;while the coverage and integrity of PEA coating were mainly affected by the monomer concentration and sweep *** F-SIMS results indicated that PEA coating was wholly covered on Mg alloy,and the presence of C2H3Mg-fragment confirmed the covalent bond between PEA coating and Mg *** addition,DFT calculation results of the adsorption of EA molecules with Mg substrate agree well with the experimental phenomena and observation,suggesting that the electrons in 3s orbit of Mg atoms and 2pz orbit of C1 atom participated in the formation of covalent bond between PEA coating and Mg *** polarization curves and immersion test demonstrated that the PEA coatings could effectively enhance the corrosion resistance of Mg *** platelet adhesion results designated that platelets were barely visible on PEA coating,which implied that PEA coating could effectively prevent the thrombosis and coagulation of *** coating might be a promising candidate coating of Mg alloy for cardiovascular stent.

关键词： Magnesium alloy Organic coating Electro-grafting Covalent bond Density functional theory Biomaterial

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Fiber-optic time transfer over a ring network with data transmission

Fiber-optic time transfer over a ring network with data tran...

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2024 Asia Communications and Photonics Conference, ACP 2024 and International Conference on Information Photonics and Optical Communications, IPOC 2024

作者： Yang, Yansong Xie, Kunfeng Ma, Yuzhe Hu, Liang Chen, Jianping Wu, Guiling State Key Laboratory of Advanced Optical Communication System and Networks Shanghai Jiao Tong University Shanghai China

ISBN: (纸本)9798350379266

In this paper, we proposed a point-to-multipoint fiber-optic time transfer scheme over ring networks. The proposed scheme is experimentally demonstrated over a 400 km ring fiber network with the communication data transmission in an adjacent channel. The results show that the clock difference with the mean value of less than 9.4 ps is obtained, and the time stability in terms of time deviation can be better than 15.17 ps@1s, while the bit error rate of the communication data transmission is better than 1.37×10-14 © 2024 IEEE.

关键词： Bit error rate

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Type Synthesis of fully-Decoupled 2T2R Parallel Mechanisms Based on Driven - Chain Principle

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Journal of Harbin Institute of Technology(New Series) 2016年第5期23卷 45-52页

作者： Yi Cao School of Mechanical Engineering Jiangnan University Wuxi Jiangsu 214122 China State Key Laboratory of Robotics and System Harbin 150080 China State Key Laboratory of Mechanical System and Vibration Shanghai 200240 China Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology Wuxi Jiangsu 214122 China

Based on the screw theory and the driven-chain principle,a methodology of structural synthesis for fully-decoupled two-translational(2T) and two-rotational(2R) parallel mechanism is proposed by analyzing the characteristics of the input-output relations for fully-decoupled parallel ***,according to the desired kinematic characteristics of fully-decoupled parallel mechanisms,a method is proposed by virtue of screw theory to synthesize the desired forms for both the direct and the inverse Jacobian ***,according to the feature of the direct and the inverse Jacobian matrices,the effective screws,the actuated screws and the mobile un-actuated screws of each leg are established based on the reciprocal screw theory and all possible topology structures fulfilling the requirements are ***,the desired fully-decoupled parallel mechanisms can be synthesized by using the structural synthesis rule and structural synthesis of fullydecoupled 2T2R parallel mechanisms can be obtained exploiting the abovementioned *** particular,the direct Jacobian matrix of each synthesized fully-decoupled 2T2R parallel mechanism is a non-zero diagonal matrix throughout the entire *** are mounted on each leg and each one of them actuates one degree-of-freedom(Do F) of the fully-decoupled parallel mechanism through a one-to-one velocity relation.

关键词： type synthesis fully-decoupled parallel mechanisms driven-chanin principle screw theory

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A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

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Chinese Journal of Mechanical Engineering 2020年第6期33卷 134-157页

作者： Yongquan Li Yang Zhang Lijie Zhang Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao066004China Key Laboratory of Advanced Forging&Stamping Technology and Science Ministry of Education of ChinaYanshan UniversityQinhuangdao066004China School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen518052China Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan UniversityQinhuangdao066004China

The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms,or using screw theory to perform multiple getting intersection and union to complete type *** number of redundant parallel mechanisms obtained by these two methods is *** this paper,based on Grassmann line geometry and Atlas method,a novel and effective method for type synthesis of redundant actuated parallel mechanisms(PMs)with closed-loop units is ***,the degree of freedom(DOF)and constraint line graph of the moving platform are determined successively,and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph,and a branch constraint allocation scheme is formulated based on the allocation ***,a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop ***,the branch chains that meet the requirements of branch chains configuration criteria and F&C(degree of freedom&constraint)line graph are *** this paper,two types of 2 rotational and 1 translational(2R1T)redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational(2T1R)redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples,and 238,92 and 15 new configurations were *** the mechanisms contain closed-loop units,and the mechanisms and the actuators both have good ***,all the mechanisms have excellent comprehensive performance,in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently *** instantaneous analysis shows that all mechanisms are not instantaneous,which proves the feasibility and practicability of the method.

关键词： Redundant actuated Parallel mechanisms Type synthesis Atlas method Instantaneous analysis

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Recent progress of photodetector based on carbon nanotube film and application in optoelectronic integration

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Nano Research Energy 2023年第2期2卷 182-199页

作者： Xiang Cai Sheng Wang Lian-Mao Peng Key Laboratory for the Physics and Chemistry of Nanodevices and Center for Carbon-Based Electronics School of ElectronicsPeking UniversityBeijing 100871China State Key Laboratory of Advanced Optical Communication System and Networks School of ElectronicsPeking UniversityBeijing 100871China

Due to its remarkable electrical and optical capabilities,optoelectronic devices based on the semiconducting single-walled carbon nanotube(s-SWCNT)have been studied extensively in the last two ***,s-SWCNT is a direct bandgap semiconductor with a high infrared absorption coefficient and high electron/hole *** addition,as a typical one-dimensional material,there is no lattice mismatch between s-SWCNT and any *** advantage is that the optoelectronic devices of s-SWCNT can be processed at low temperatures.s-SWCNT has intriguing potential and applications in solar cells,light-emitting diodes(LEDs),photodetectors,and three-dimensional(3D)optoelectronic *** recent years,along with the advancement of solution purification technology,the high-purity s-SWCNTs film has laid the foundation for constructing large-area,homogenous,and high-performance optoelectronic *** this review,optoelectronic devices based on s-SWCNTs film and related topics are reviewed,including the preparation of high purity s-SWCNTs film,the progress of photodetectors based on the s-SWCNTs film,and challenges of s-SWCNTs film photodetectors.

关键词： carbon nanotube high purity semiconducting single-walled carbon nanotubes(s-SWCNTs)film photodetectors optoelectronic integration

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Design of Mixed Reality Assembly system Based on Improved ORB Algorithm 3

Design of Mixed Reality Assembly System Based on Improved OR...

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3rd International Conference on Computer Vision, Image and Deep Learning and International Conference on Computer Engineering and Applications, CVIDL and ICCEA 2022

作者： Lu, Na Xiao, YongFei Zhao, Jie Shandong Provincial Key Laboratory of Robot and Manufacturing Automation Technology ShanDong China Harbin Institute of Technology Institute of Automation Shandong State Key Laboratory of Robotics and System Harbin China

ISBN: (纸本)9781665459112

This paper studies the natural feature point detection algorithm in a virtual assembly system. To address the problems of unsatisfactory detection effect and poor matching accuracy of the ORB algorithm, a feature uniform distribution algorithm based on pyramidal grid division is proposed, and a strategy of retaining feature points according to Harris response values is formulated to solve the problem of feature point aggregation while ensuring extraction speed. Hamming distance and the RANSAC algorithm are used to constrain the matching results. The robot assembly system based on this algorithm overlays the 3D model of the spraying robot and virtual information in the mobile device to improve the assembly efficiency of the staff. The experimental results show that the mixed reality(MR) assembly system based on the algorithm of this paper performs well, and the real-time performance and alignment accuracy are improved. © 2022 IEEE.

关键词： Assembly

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Cs 728 nm Laser Spectroscopy and Faraday Atomic Filter

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Chinese Physics Letters 2014年第12期31卷 27-30页

作者：刘忠征陶智明蒋招杰陈景标 State Key Laboratory of Advanced Optical Communication System and Network Institute of Quantum Electronics School of Electronics Engineering ~ Computer Science Peking University Beijing 100871 College of Science Guizhou University of Engineering Science Bijie 551700

The laser spectroscopy of alkali-metal vapor is widely used in a number of applications, such as the Faraday anomalous dispersion optical fil- ter （FADOF）, the active optical clock, and wavelength ***＇ The Cs electrodeless dis- charge vapor lamp has rich spectra, including 455 nm, 459 nm, 728 nm, 852 nm, 1359 nm, and 1470 nm. The 852 nm laser pumping atoms from 6S1/2 to 6P3/2 have been used in *** 1359nm wave- length transited from 7S1/2 to 6P1/2 of Cs atoms can be used in the field of active optical clocks. The concept of active optical clocks has been proposed since 2005. Due to its good performance in sta- bility, the active optical clock has been extensively in- vestigated theoretically and experimentally in recent years, such as the two-level active optical clock, and three-level active optical clock. When considering the performance of the active optical clock, we hope to reduce the second-order Doppler shift in thermal atomic beam and the light shift induced by the pump- ing laser. To solve this issue, our group has recently proposed a four-level active optical clock, such as K 1252.2nm, Cs 1469nm, Rb 1366.9nm and Rb 728 nm. Moreover, the Rb 728 nm four-level quantum system has potentially a better performance than three long wavelength ones of Rb.

关键词： LASER spectroscopy CESIUM FARADAY effect INDUCTION lamps PHASE transformations (Physics) LIGHT filters

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Hierarchical Trajectory Optimization for Humanoid robot Jumping Motion 16th

Hierarchical Trajectory Optimization for Humanoid Robot Jump...

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16th International Conference on Intelligent robotics and Applications, ICIRA 2023

作者： Sun, Junbao Liu, Haopeng Li, Xu Feng, Haibo Fu, Yili Zhang, Songyuan Intelligent Robot Research Center Zhejiang Laboratory Hangzhou311100 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China

ISBN: (纸本)9789819964796

In order to make the robot have high dynamic motion ability, this paper uses the trajectory optimization method to plan the jumping motion trajectory of the humanoid robot quickly and effectively, and carries out the jumping motion experiment on the HIT-HU humanoid robot platform. In order to improve the solving speed of trajectory optimization problem, simplified centroid dynamics model and single rigid body model are established. Differential dynamic programming (DDP) based on the combination of the centroid dynamic model and the whole body joint kinematic model is used to solve the hopping trajectory optimization problem with high accuracy, and the external penalty function method is used to deal with the relevant constraints. In order to overcome the problem that the solver is sensitive to the initial point selection, a hierarchical trajectory optimization framework is proposed. The framework uses the direct collocation method based on the single rigid body model. The trajectory of the simplified model is used as the initial trajectory guess, and the differential dynamic programming method is introduced to solve the optimal trajectory of the whole joint. The differential dynamic programming algorithm using the direct method of warm start is about twice as fast as the method of manually given initial trajectory. The simulation and experimental verification of the vertical jump trajectories generated by the algorithm on the humanoid robot HIT-HU show that the jump trajectories generated by the algorithm can be effectively transformed into the motion trajectories of humanoid robots, and can be effectively executed on the physical prototype. This further verifies the effectiveness of the algorithm and plays an important role in practical application. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

关键词： Anthropomorphic robots

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