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Long-term ultrastable frequency dissemination via a 50-km spooled fiber link using a two-section DFB laser

Chinese Optics Letters 2024年第1期22卷 164-169页

作者：尹知谦张川博管世健周昕王亚光王磊磊郑满航刘奕彤张云山朱兴邦方涛陈向飞 Engineering research Center of precision Photonics integration and system Application Ministry of Education&Key Laboratory of Intelligent Optical Sensing and ManipulationMinistry of Education&National Laboratory of Solid State Microstructures&College of Engineering and Applied Sciences&Institute of Optical Communication Engineering&Nanjing University-Tongding Joint Lab for Large-Scale Photonic Integrated CircuitsNanjing UniversityNanjing 210023China College of Electronics and Optical Engineering and College of Flexible Electronics Nanjing University of Posts and TelecommunicationsNanjing 210023China The 41st research Institute of China Electronics Technology Group Corp Qingdao 266000China

The stable long-distance transmission of radio-frequency(RF)signals holds significant importance from various aspects,including the comparison of optical frequency standards,remote monitoring and control,scientific research and experiments,and RF spectrum *** demonstrate a scheme where an ultrastable frequency signal was transmitted over a 50 km coiled *** optical RF signal is generated using a two-section distributed feedback(DFB)laser for direct modulation based on the reconstruction equivalent chirp(REC)*** 3-dB modulation bandwidth of the two-section DFB laser is 18 GHz and the residual phase noise of-122.87 dBc/Hz is achieved at 10-Hz offset *** report a short-term stability of 1.62×10^(-14)at an average time of 1 s and a long-term stability of 6.55×10^(-18)at the measurement time of 62,000 s when applying current to the front section of the DFB *** applying power to both sections,the stability of the system improves to 4.42×10^(-18)within a testing period of 56,737 *** applying temperature variations to the transmission link,long-term stability of 8.63×10^(-18)at 23.9 h can still be achieved.

关键词： frequency dissemination two-section DFB laser phase stability

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Stability-enhanced RF signal transmission over long fiber-optic links

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Chinese Optics Letters 2024年第5期22卷 131-136页

作者：尹知谦郑满航张川博管世健周昕刘奕彤刚泽宇聂佳强张云山朱兴邦方涛陈向飞 Engineering research Center of precision Photonics integration and system Application Ministry of Education&Key Laboratory of Intelligent Optical Sensing and ManipulationMinistry of Education&National Laboratory of Solid State Microstructures&College of Engineering and Applied Sciences&Institute of Optical Communication Engineering&Nanjing University-Tongding Joint Lab for Large-scale Photonic Integrated CircuitsNanjing UniversityNanjing 210023China College of Electronics and Optical Engineering and College of Flexible Electronics(Future Technology) Nanjing University of Posts and TelecommunicationsNanjing 210023China The 41st research Institute of China Electronics Technology Group Corp Qingdao 266000China

We propose a method for optimizing the phase stability of microwave signal transmission over long ***,the design of the photon link was modified to reduce the radio frequency(RF)signal’s baseline noise and increase ***,a low-noise driver circuit was developed for a two-section distributed feedback(DFB)laser designed using reconstruction equivalent chirp(REC)technology to create an ultra-stable laser,and its performance was characterized through linewidth *** results indicate that the DFB laser achieved narrower linewidth,improving system phase *** an injection current(30 mA)is applied to the reflection section of the two-section DFB laser,the laser linewidth will be narrower(1.38 MHz),further enhancing the system’s phase transmission *** a 1 Hz offset frequency,a residual phase noise of-88.65 dBc/Hz is *** short-term stability with an averaging time of 1 s is 1.60×10^(-14),and the long-term stability over a testing time of 60,000 s is 3.41×10^(-18).Even after incorporating temperature variations,the long-term stability reaches 8.37×10^(-18) at 22 h.

关键词： frequency dissemination two-section distributed feedback laser phase stability

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A real-time performance improvement method for composite time scale

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Chinese Physics B 2024年第09期 354-361页

作者：王芳敏李汶林戴鸿飞李春怡周建华薛申辉王波 State key laboratory of precision Space–time Information Sensing Technology Department of Precision InstrumentTsinghua University key laboratory of Photonic Control TechnologyTsinghua University Ministry of Education Beijing Satellite Navigation Center

The composite time scale(CTS) provides a stable, accurate, and reliable time scale for modern society. The improvement of CTS's real-time performance will improve its stability, which strengths related applications' *** at this goal, a method achieved by determining the optimal calculation interval and accelerating adjustment stage is proposed in this paper. The determinants of the CTS's calculation interval(characteristics of the clock ensemble, the measurement noise, the time and frequency synchronization system's noise and the auxiliary output generator noise floor)are studied and the optimal calculation interval is obtained. We also investigate the effect of ensemble algorithm's initial parameters on the CTS's adjustment stage. A strategy to get the reasonable initial parameters of ensemble algorithm is designed. The results show that the adjustment stage can be finished rapidly or even can be shorten to zero with reasonable initial parameters. On this basis, we experimentally generate a distributed CTS with a calculation interval of 500 s and its stability outperforms those of the member clocks when the averaging time is longer than ～ 1700 s. The experimental result proves that the CTS's real-time performance is significantly improved.

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Comprehensive study of the ultrafast photoexcited carrier dynamics in Sb_(2)Te_(3)–GeTe superlattices

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Chinese Physics B 2024年第7期33卷 381-387页

作者：叶之江金钻明蒋叶昕卢琦贾梦辉钱冬黄夏敏李舟彭滟朱亦鸣 Terahertz Technology Innovation research Institute Terahertz Spectrum and Imaging Technology Cooperative Innovation CenterShanghai Key Laboratory of Modern Optical SystemUniversity of Shanghai for Science and TechnologyShanghai 200093China Shanghai Institute of Intelligent Science and Technology Tongji UniversityShanghai 200092China key laboratory of Artificial Structures and Quantum Control(ministry of education) Shenyang National Laboratory for Materials ScienceSchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China State key laboratory of precision Spectroscopy East China Normal UniversityShanghai 200062China GBA Branch of Aerospace Information research Institute Chinese Academy of SciencesGuangzhou 510700China Guangdong Provincial key laboratory of Terahertz Quantum Electromagnetics Guangzhou 510700China University of Chinese Academy of Sciences Beijing 100039China

Chalcogenide superlattices Sb_(2)Te_(3)-GeTe is a candidate for interfacial phase-change memory(iPCM) data storage *** employing terahertz emission spectroscopy and the transient reflectance spectroscopy together,we investigate the ultrafast photoexcited carrier dynamics and current transients in Sb_(2)Te_(3)-GeTe *** orientation and excitation polarization dependences of the THz emission confirm that ultrafast thermo-electric,shift and injection currents contribute to the THz generation in Sb_(2)Te_(3)-GeTe *** decreasing the thickness and increasing the number of GeTe and Sb_(2)Te_(3) layer,the interlayer coupling can be enhanced,which significantly reduces the contribution from circular photo-galvanic effect(CPGE).A photo-induced bleaching in the transient reflectance spectroscopy probed in the range of~1100 nm to~1400 nm further demonstrates a gapped state resulting from the interlayer *** demonstrates play an important role in the development of iPCM-based high-speed optoelectronic devices.

关键词： Sb_(2)Te_(3)/GeTe superlattices ultrafast carrier dynamics interfacial phase change memory THz emission spectroscopy transient reflectance spectroscopy

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Development of a Vehicle-Mounted Crop Detection system

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Journal of Integrative agriculture 2014年第6期13卷 1284-1292页

作者： ZHONG Zhen-jiang SUN Hong LI Min-zan ZHANG Feng LI Xiu-hua key laboratory of modern precision agriculture system integration research Ministry of Education/China Agricultural University

In order to monitor plant chlorophyll content in real-time, a new vehicle-mounted detection system was developed to measure crop canopy spectral characteristics. It was designed to work as a wireless sensor network with one control unit and one measuring unit. The control unit included a personal digital assistant （PDA） device with a ZigBee wireless network coordinator. As the coordinator of the whole wireless network, the control unit was used to receive, display and store all the data sent from sensor nodes. The measuring unit consisted of several optical sensor nodes. All the sensor nodes were mounted on an on-board mechanical structure so that the measuring unit could collect the canopy spectral data while moving. Each sensor node contained four optical channels to measure the light radiation at the wavebands of 550, 650, 766, and 850 nm. The calibration tests veriifed a good performance in terms of the wireless transmission ability and the sensor measurement precision. Both stationary and moving ifeld experiments were also conducted in a winter wheat experimental ifeld. There was a high correlation between chlorophyll content and vegetation index, and several estimation models of the chlorophyll content were established. The highest R2 of the estimation models was 0.718. The results showed that the vehicle-mounted crop detection system has potential for ifeld application.

关键词： optical sensor vegetation index chlorophyll content ZigBee wireless sensor network (WSN)

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Multi-source information fusion:Progress and future

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Chinese Journal of Aeronautics 2024年第7期37卷 24-58页

作者： Xinde LI Fir DUNKIN Jean DEZERT School of Automation Southeast UniversityNanjing 210008China Nanjing Center for Applied Mathematics Nanjing 211135China key laboratory of Measurement and Control of CSE Ministry of EducationNanjing 210096China Southeast University Shenzhen research Institute Shenzhen 518063China Information Modeling and Processing Department ONERAPalaiseau 92320France

Multi-Source Information Fusion(MSIF),as a comprehensive interdisciplinary field based on modern information technology,has gained significant research value and extensive application prospects in various domains,attracting high attention and interest from scholars,engineering experts,and practitioners *** achieving fruitful results in both theoretical and applied aspects over the past five decades,there remains a lack of comprehensive and systematic review articles that provide an overview of recent development in *** light of this,this paper aims to assist researchers and individuals interested in gaining a quick understanding of the relevant theoretical techniques and development trends in MSIF,which conducts a statistical analysis of academic reports and related application achievements in the field of MSIF over the past two decades,and provides a brief overview of the relevant theories,methodologies,and application domains,as well as key issues and challenges currently ***,an analysis and outlook on the future development directions of MSIF are presented.

关键词： Multi-sensor system Information fusion Artificial intelligence Pattern recognition Human-machine integration

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Enhancing Autonomy Capability in Regional Power Grids:A Strategic Planning Approach with Multiple Autonomous Evaluation Indexes

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Energy Engineering 2024年第9期121卷 2449-2477页

作者： Jie Ma Tong Zhao Yuanzhao Hao Wenwen Qin Haozheng Yu Mingxuan Du Yuanhong Liu Liang Zhang Shixia Mu Cuiping Li Junhui Li Planning and Assessment Center Department State Grid Henan Economic Research InstituteZhengzhou450000China key laboratory of modern Power system Simulation and Control&Renewable Energy Technology Ministry of EducationNortheast Electric Power UniversityJilin132012China Development Planning Department State Grid Henan Electric Power CompanyZhengzhou450000China Innovation Development research Center State Grid Shanghai Energy Internet Research Institute Co.Ltd.Shanghai201210China State Grid Simulation Center China Electric Power Research Institute Co.Ltd.Beijing100192China

After the integration of large-scale DistributedGeneration(DG)into the distribution network,the randomness and volatility of its output result in a reduction of spatiotemporal alignment between power generation and demand in the distribution network,exacerbating the phenomenon of wind and solar power *** a novel power system model,the fundamental concept of Regional Autonomous Power Grids(RAPGs)is to achieve localized management and energy autonomy,thereby facilitating the effective consumption of ***,this paper proposes a distributed resource planning strategy that enhances the autonomy capabilities of regional power grids by considering multiple evaluation indexes for ***,a regional Energy Storage(ES)configuration strategy is *** strategy can select a suitable reference value for the upper limit of ES configuration based on the regional load andDGoutput to maximize the elimination of source load deviations in the region as the upper limit constraint of ES ***,a control strategy for regional ES is proposed,the charging and discharging reference line of ES is set,and multiple autonomy and economic indexes are used as objective functions to select different proportions of ES to control the distributed resources of the regional power grid and establish evaluation indexes of the internal regional generation and load power ratio,the proportion of power supply matching hours,new energy consumption rate and tie line power imbalance outside the region to evaluate changes in the regional autonomy *** final simulation results showthat in the real regional grid example,the planning method in the planning year in the region of the overall power supply matching hour ratio and new energy consumption rate increased by 3.9%and 4.8%on average,and the power imbalance of the tie line decreased by 7.8%on *** proposed planning approach enables the maximization of regional autonomy while effectively smoothing the fluct

关键词： Regional autonomous power grid distributed generation distributed energy storage regional planning strategy evaluation index

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Development and application of crop monitoring system for detecting chlorophyll content of tomato seedlings

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International Journal of Agricultural and Biological Engineering 2014年第2期7卷 138-145页

作者： Wu Qian Sun Hong Li Minzan Yang Wei key laboratory of modern precision agriculture system integration research Ministry of EducationChina Agricultural UniversityBeijing 100083China

A crop monitoring system was developed to nondestructively monitor the crop growth status in the *** a two channel multispectral camera with one lens,controlling platform,wireless remote control module and control software,the system was able to synchronously acquire visible image(red(R),green(G),blue(B):400-700 nm)and near-infrared(NIR)image(760-1000 nm).The tomato seedlings multi-spectral images collection experiment in the greenhouse was conducted by using the developed system from the seeding stage to fruiting *** than 240 couples of tomato seedlings pictures were acquired with the Soil and Plant Analyzer Development(SPAD)value measured at the same *** obtained images were available to process,and some vegetation indexes,such as normalized difference vegetation index(NDVI),ratio vegetation index(RVI)and normalized difference green index(NDGI),were *** the SPAD value and the correlation coefficient between SPAD and other parameters in different fertilization treatments,the multiple linear regressions(MLR)model for estimating tomato seedlings chlorophyll content was built based on the average gray value in red,green,blue and NIR,vegetable indexes,NDVI,RVI and NDGI in the 33.3%(N1),66.6%(N2),and 100%(N3)nutrient levels during seeding stage and blossom and fruit *** R2 of the model is *** results revealed that the developed crop monitoring system provided a feasible tool to detect the growth status of *** filed experiments and multi-spectral image analysis will be investigated to evaluate the crop growth status in the near future.

关键词： multi-spectral image crop growth status image acquisition 2-CCD sensor precision agriculture

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Intelligent data acquisition and cloud services for apple orchard

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International Journal of Agricultural and Biological Engineering 2014年第2期7卷 146-153,I0004页

作者： Guo Xiang Zheng Lihua Li Minzan Zhang Yao key laboratory of modern precision agriculture system integration research ministry of education China Agricultural UniversityBeijing 100083China

An intelligent data acquisition and service system for apple orchard was developed for acquiring apple tree growth information in time and managing orchard production *** data of fruit tree growth environment were collected by Portable Digital Assistant(PDA)through the ZigBee Wireless Sensors Network(WSN)deployed in the apple *** collected data were packaged and uploaded following the transportation protocol through the web service interface provided by the orchard *** that the orchard data were parsed and stored using distributed ***,the data could be processed,analyzed and visualized by the cloud orchard server,and the orchard production decisions based on WebGIS technology could be made as *** the users could access the services provided by the network platform via remote mobile or fixed *** system operation test showed that the whole process was stable and reliable,during which intelligent data collection,storage,and cloud data processing and publishing services were achieved.

关键词： orchard PDA WSN WebGIS distributed storage web service

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Evaluation of Multi-Temporal-Spatial Scale Adjustment Capability and Cluster Optimization Operation Method for Distribution Networks with Distributed Photovoltaics

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Energy Engineering 2024年第9期121卷 2655-2680页

作者： Jiaxin Qiao Yuchen Hao Yingqi Liao Fang Liang Jing Bian Northeast Electric Power University Key Laboratory of Modern Power System Simulation and Control&Renewable Energy TechnologyMinistry of EducationJilin132011China State Grid Jiangsu Electric Power Co. Ltd.Power Dispatch Control CenterNanjing210017China State Grid Jiangsu Electric Power Co. Ltd.Nanjing Power Supply BranchPower Dispatch Control CenterNanjing210019China

Themassive integration of high-proportioned distributed photovoltaics into distribution networks poses significant challenges to the flexible regulation capabilities of distribution *** accurately assess the flexible regulation capabilities of distribution stations,amulti-temporal and spatial scale regulation capability assessment technique is proposed for distribution station areas with distributed photovoltaics,considering different geographical locations,coverage areas,and response ***,the multi-temporal scale regulation characteristics and response capabilities of different regulation resources in distribution station areas are analyzed,and a resource regulation capability model is established to quantify the adjustable range of different regulation *** this basis,considering the limitations of line transmission capacity,a regulation capability assessment index for distribution stations is proposed to evaluate their regulation ***,considering different geographical locations and coverage areas,a comprehensive performance index based on electrical distance modularity and active power balance is established,and a cluster division method based on genetic algorithms is proposed to fully leverage the coordination and complementarity among nodes and improve the active power matching degree within ***,an economic optimization model with the objective of minimizing the economic cost of the distribution station is established,comprehensively considering the safety constraints of the distribution network and the regulation constraints of *** model can provide scientific guidance for the economic dispatch of the distribution station ***,case studies demonstrate that the proposed assessment and optimization methods effectively evaluate the regulation capabilities of distribution stations,facilitate the consumption of distributed photovoltaics,and enhance the economic efficiency of th

关键词： Distributed photovoltaic distribution station area assessment of adjustment capacity line transmission capacity economic optimization

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