A distributed online fiber sensing system based on the phase-sensitive optical time domain reflectometer(Φ-OTDR)enhanced by the drawing tower fiber Bragg grating(FBG)array is presented and investigated experimentally...A distributed online fiber sensing system based on the phase-sensitive optical time domain reflectometer(Φ-OTDR)enhanced by the drawing tower fiber Bragg grating(FBG)array is presented and investigated experimentally for monitoring the galloping of overhead transmission lines.The chirped FBG array enhanced Φ-OTDR sensing system can be used to measure the galloping behavior of the overhead transmission lines(optical phase conductor or optical power ground wire),which are helpful for monitoring the frequency response characteristics of the ice-induced galloping,evaluating the motion tendencies of these cables,and avoiding the risk of flashover during galloping.The feasibility of the proposed online monitoring system is demonstrated through a series of experiments at the Special Optical Fiber Cable Laboratory of State Grid Corporation of China(Beijing,China).Results show that the proposed system is effective and reliable for the monitoring of galloping shape and characteristic frequency,which can predict the trend of destructive vibration behavior and avoid the occurrence of cable breaking and tower toppling accidents,and these features are essential for the safety operation in smart grids.展开更多
Due to the limited scenes that synthetic aperture radar(SAR)satellites can detect,the full-track utilization rate is not high.Because of the computing and storage limitation of one satellite,it is difficult to process...Due to the limited scenes that synthetic aperture radar(SAR)satellites can detect,the full-track utilization rate is not high.Because of the computing and storage limitation of one satellite,it is difficult to process large amounts of data of spaceborne synthetic aperture radars.It is proposed to use a new method of networked satellite data processing for improving the efficiency of data processing.A multi-satellite distributed SAR real-time processing method based on Chirp Scaling(CS)imaging algorithm is studied in this paper,and a distributed data processing system is built with field programmable gate array(FPGA)chips as the kernel.Different from the traditional CS algorithm processing,the system divides data processing into three stages.The computing tasks are reasonably allocated to different data processing units(i.e.,satellites)in each stage.The method effectively saves computing and storage resources of satellites,improves the utilization rate of a single satellite,and shortens the data processing time.Gaofen-3(GF-3)satellite SAR raw data is processed by the system,with the performance of the method verified.展开更多
A wideband wavelength-tunable 4×5 distributed feedback(DFB)semiconductor laser array based on the reconstructionequivalent-chirp(REC)technique using a simple tuning scheme is demonstrated.It consists of 20 DFB la...A wideband wavelength-tunable 4×5 distributed feedback(DFB)semiconductor laser array based on the reconstructionequivalent-chirp(REC)technique using a simple tuning scheme is demonstrated.It consists of 20 DFB lasers with 4×5matrix interleaving distributions,two-level cascaded Y-branch optical combiners,and one active semiconductor opticalamplifier(SOA),all in-series integrated on one chip.Unlike the traditional thermal-electric cooler(TEC)-based wavelength-tuning scheme,the tunable 4×5 REC-DFB laser array achieves a faster and broader continuous wavelength-tuningrange using TaN thin-film heaters integrated on the AlN submount.By changing the injection current of the TaN resistorfrom 0 to 190 mA,the proposed tunable laser achieves a wavelength-tuning range of∼2.5 nm per channel and a total tuningof over 50 nm.This study opens up new avenues for realizing cost-effective and wide-tuning-range semiconductor lasers.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61775173,61975157,and 52071245)the Science and Technology Project of State Grid Corporation of China(Research on the basic technology of the next generation intelligent optical cable based on grating array fiber sensor,Grant No.5442XX190009).
文摘A distributed online fiber sensing system based on the phase-sensitive optical time domain reflectometer(Φ-OTDR)enhanced by the drawing tower fiber Bragg grating(FBG)array is presented and investigated experimentally for monitoring the galloping of overhead transmission lines.The chirped FBG array enhanced Φ-OTDR sensing system can be used to measure the galloping behavior of the overhead transmission lines(optical phase conductor or optical power ground wire),which are helpful for monitoring the frequency response characteristics of the ice-induced galloping,evaluating the motion tendencies of these cables,and avoiding the risk of flashover during galloping.The feasibility of the proposed online monitoring system is demonstrated through a series of experiments at the Special Optical Fiber Cable Laboratory of State Grid Corporation of China(Beijing,China).Results show that the proposed system is effective and reliable for the monitoring of galloping shape and characteristic frequency,which can predict the trend of destructive vibration behavior and avoid the occurrence of cable breaking and tower toppling accidents,and these features are essential for the safety operation in smart grids.
基金Project(2017YFC1405600)supported by the National Key R&D Program of ChinaProject(18JK05032)supported by the Scientific Research Project of Education Department of Shaanxi Province,China。
文摘Due to the limited scenes that synthetic aperture radar(SAR)satellites can detect,the full-track utilization rate is not high.Because of the computing and storage limitation of one satellite,it is difficult to process large amounts of data of spaceborne synthetic aperture radars.It is proposed to use a new method of networked satellite data processing for improving the efficiency of data processing.A multi-satellite distributed SAR real-time processing method based on Chirp Scaling(CS)imaging algorithm is studied in this paper,and a distributed data processing system is built with field programmable gate array(FPGA)chips as the kernel.Different from the traditional CS algorithm processing,the system divides data processing into three stages.The computing tasks are reasonably allocated to different data processing units(i.e.,satellites)in each stage.The method effectively saves computing and storage resources of satellites,improves the utilization rate of a single satellite,and shortens the data processing time.Gaofen-3(GF-3)satellite SAR raw data is processed by the system,with the performance of the method verified.
基金supported by the Chinese National Key Basic Research Special Fund(Nos.2017YFA0206401,2018YFA0704402,2018YFB2201801,and 2018YFE0201200)National Key Research and Development Program of China(No.2020YFB2205800)+2 种基金National Natural Science Foundation of China(Nos.61975075,61975076,and 62004094)Natural Science Foundation of Jiangsu Province(No.BK20200334)Jiangsu Science and Technology Project(No.BE2017003-2).
文摘A wideband wavelength-tunable 4×5 distributed feedback(DFB)semiconductor laser array based on the reconstructionequivalent-chirp(REC)technique using a simple tuning scheme is demonstrated.It consists of 20 DFB lasers with 4×5matrix interleaving distributions,two-level cascaded Y-branch optical combiners,and one active semiconductor opticalamplifier(SOA),all in-series integrated on one chip.Unlike the traditional thermal-electric cooler(TEC)-based wavelength-tuning scheme,the tunable 4×5 REC-DFB laser array achieves a faster and broader continuous wavelength-tuningrange using TaN thin-film heaters integrated on the AlN submount.By changing the injection current of the TaN resistorfrom 0 to 190 mA,the proposed tunable laser achieves a wavelength-tuning range of∼2.5 nm per channel and a total tuningof over 50 nm.This study opens up new avenues for realizing cost-effective and wide-tuning-range semiconductor lasers.
