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| 1 | Semi-tightly coupled integration of multi-GNSS PPP and S-VINS for precise positioning in GNSS-challenged environments显示文摘Because of its high-precision,low-cost and easy-operation,Precise Point Positioning(PPP)becomes a potential and attractive positioning technique that can be applied to self-driving cars and drones.However,the reliability and availability of PPP will be significantly degraded in the extremely difficult conditions where Global Navigation Satellite System(GNSS)signals are blocked frequently.Inertial Navigation System(INS)has been integrated with GNSS to ameliorate such situations in the last decades.Recently,the Visual-Inertial Navigation Systems(VINS)with favorable complementary characteristics is demonstrated to realize a more stable and accurate local position estimation than the INS-only.Nevertheless,the system still must rely on the global positions to eliminate the accumulated errors.In this contribution,we present a semi-tight coupling framework of multi-GNSS PPP and Stereo VINS(S-VINS),which achieves the bidirectional location transfer and sharing in two separate navigation systems.In our approach,the local positions,produced by S-VINS are integrated with multi-GNSS PPP through a graph-optimization based method.Furthermore,the accurate forecast positions with S-VINS are fed back to assist PPP in GNSS-challenged environments.The statistical analysis of a GNSS outage simulation test shows that the S-VINS mode can effectively suppress the degradation of positioning accuracy compared with the INS-only mode.We also carried out a vehicle-borne experiment collecting multi-sensor data in a GNSS-challenged environment.For the complex driving environment,the PPP positioning capability is significantly improved with the aiding of S-VINS.The 3D positioning accuracy is improved by 49.0%for Global Positioning System(GPS),40.3%for GPS+GLOANSS(Global Navigation Satellite System),45.6%for GPS+BDS(BeiDou navigation satellite System),and 51.2%for GPS+GLONASS+BDS.On this basis,the solution with the semi-tight coupling scheme of multi-GNSS PPP/S-VINS achieves the improvements of 41.8-60.6%in 3D position-ing accuracy compared with the multi-GNSS PPP/INS solutions. | Xingxing Li Xuanbin Wang Jianchi Liao Xin Li Shengyu Li Hongbo Lyu | 2021 | Satellite Navigation2021，2，1： | 10 |
| 2 | Non-suicidal self-harm is linked to suicidal thoughts in Chinese adolescents with mood disorders:a cross-sectional report显示文摘Non-suicidal self-injury (NS SI) refers to any intentional,self-inflicted behavior that causes direct damage to body tissues (Kerr et al.,2010),and has emerged as a challenging public health issue worldwide,especially among adolescents.The most common presentations of NSSI include skin-cutting,severe scratching,and burning (Whitlock et al,2006). | Yixin WANG Jianbo LAI Chanchan HU Hongbo MENG Duo LYU Shaohua HU | 2021 | Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)2021，22，3： | 5 |
| 3 | MATRIEX imaging:multiarea two-photon real-time in vivo explorer显示文摘Two-photon laser scanning microscopy has been extensively applied to study in vivo neuronal activity at cellular and subcellular resolutions in mammalian brains.However,the extent of such studies is typically confined to a single functional region of the brain.Here,we demonstrate a novel technique,termed the multiarea two-photon real-time in vivo explorer(MATRIEX),that allows the user to target multiple functional brain regions distributed within a zone of up to 12mm in diameter,each with a field of view(FOV)of ~200μm in diameter,thus performing two-photon Ca2+imaging with single-cell resolution in all of the regions simultaneously.For example,we demonstrate real-time functional imaging of single-neuron activities in the primary visual cortex,primary motor cortex and hippocampal CA1 region of mice in both anesthetized and awake states.A unique advantage of the MATRIEX technique is the configuration of multiple microscopic FOVs that are distributed in three-dimensional space over macroscopic distances(>1 mm)both laterally and axially but that are imaged by a single conventional laser scanning device.In particular,the MATRIEX technique can be effectively implemented as an add-on optical module for an existing conventional single-beam-scanning two-photon microscope without requiring any modification to the microscope itself.Thus,the MATRIEX technique can be readily applied to substantially facilitate the exploration of multiarea neuronal activity in vivo for studies of brain-wide neural circuit function with single-cell resolution. | Mengke Yang Zhenqiao Zhou Jianxiong Zhang Shanshan Jia Tong Li Jiangheng Guan Xiang Liao Bing Leng Jing Lyu Kuan Zhang Min Li Yan Gong Zhiming Zhu Junan Yan Yi Zhou Jian K Liu Zsuzsanna Varga Arthur Konnerth Yuguo Tang Jinsong Gao Xiaowei Chen Hongbo Jia | 2019 | Light(Science & Applications)2019，8，1： | 4 |
| 4 | Principle and performance of multi-frequency and multi-GNSS PPP-RTK显示文摘PPP-RTK which takes full advantages of both Real-Time Kinematic(RTK)and Precise Point Positioning(PPP),is able to provide centimeter-level positioning accuracy with rapid integer Ambiguity Resolution(AR).In recent years,with the development of BeiDou Navigation Satellite System(BDS)and Galileo navigation satellite system(Galileo)as well as the modernization of Global Positioning System(GPS)and GLObal NAvigation Satellite System(GLONASS),more than 140 Global Navigation Satellite System(GNSS)satellites are available.Particularly,the new-generation GNSS satellites are capable of transmitting signals on three or more frequencies.Multi-GNSS and multi-frequency observations become available and can be used to enhance the performance of PPP-RTK.In this contribution,we develop a multi-GNSS and multi-frequency PPP-RTK model,which uses all the available GNSS observations,and comprehensively evaluate its performance in urban environments from the perspectives of positioning accuracy,convergence and fxing percentage.In this method,the precise atmospheric corrections are derived from the multi-frequency and multi-GNSS observations of a regional network,and then disseminated to users to achieve PPP rapid AR.Furthermore,a cascade ambiguity fxing strategy using Extra‐Wide‐Lane(EWL),Wide-Lane(WL)and L1 ambiguities is employed to improve the performance of ambiguity fxing in the urban environments.Vehicle experiments in diferent scenarios such as suburbs,overpasses,and tunnels are conducted to validate the proposed method.In suburbs,an accuracy of within 2 cm in the horizontal direction and 4 cm in the vertical direction,with the fxing percentage of 93.7%can be achieved.Compared to the GPS-only solution,the positioning accuracy is improved by 87.6%.In urban environments where signals are interrupted frequently,a fast ambiguity re-fxing can be achieved within 5 s.Moreover,multifrequency GNSS signals can further improve the positioning performance of PPP-RTK,particularly in the case of small amount of observations.These results demonstrate that the multi-frequency and multi-GNSS PPP-RTK is a promising tool for supporting precise vehicle navigation. | Xingxing Li Bo Wang Xin Li Jiaxin Huang Hongbo Lyu Xinjuan Han | 2022 | Satellite Navigation2022，3，1： | 3 |
| 5 | Lipidomic and transcriptomic analysis reveals reallocation of carbon flux from cuticular wax into plastid membrane lipids in a glossy“Newhall”navel orange mutant显示文摘Both cuticle and membrane lipids play essential roles in quality maintenance and disease resistance in fresh fruits.Many reports have indicated the modification of alternative branch pathways in epicuticular wax mutants;however,the specific alterations concerning lipids have not been clarified thus far.Here,we conducted a comprehensive,timeresolved lipidomic,and transcriptomic analysis on the“Newhall”navel orange(WT)and its glossy mutant(MT)“Gannan No.1”.The results revealed severely suppressed wax formation accompanied by significantly elevated production of 36-carbon plastid lipids with increasing fruit maturation in MT.Transcriptomics analysis further identified a series of key functional enzymes and transcription factors putatively involved in the biosynthesis pathways of wax and membrane lipids.Moreover,the high accumulation of jasmonic acid(JA)in MT was possibly due to the need to maintain plastid lipid homeostasis,as the expression levels of two significantly upregulated lipases(CsDAD1 and CsDALL2)were positively correlated with plastid lipids and characterized to hydrolyze plastid lipids to increase the JA content.Our results will provide new insights into the molecular mechanisms underlying the natural variation of plant lipids to lay a foundation for the quality improvement of citrus fruit. | Haoliang Wan Hongbo Liu Jingyu Zhang Yi Lyu Zhuoran Li Yizhong He Xiaoliang Zhang Xiuxin Deng Yariv Brotman Alisdair RFernie Yunjiang Cheng Weiwei Wen | 2020 | Horticulture Research2020，7，1： | 2 |
| 6 | Study of the characteristics of rocket-triggered lightning energetic radiation and its relationships with the discharge parameters显示文摘Through the use of the independently developed Thunderstorm Energetic Radiation Observation System(TEROS),observation experiments of rocket-triggered lightning energetic radiation(RLER)were conducted for the first time at the Field Experiment Base on Lightning Sciences,China Meteorological Administration from May 2021 to July 2021.A total of 17 X-ray bursts were detected during all of the 22 leader/return strokes.In this study,the energy,time,and direction characteristics of Xray burst and its relationships with the corresponding discharge parameters,such as the return stroke peak current,half-peak width,rise time,and interstroke time interval,as well as the associated physical processes,are analyzed and discussed.Results showed that energetic radiation is ubiquitous in triggered lightning and is closely related to the last downward leader phase before the return stroke.The photon energies were concentrated in tens to hundreds of ke V,and the average duration of RLER was approximately 27μs.Moreover,RLER exhibited directional property inconsistent with a vertical downward beam,which may be related to the development orientation of the lightning leader.The intensity of RLER was positively correlated with the return stroke peak current,indicating that it directly depends on the lightning intensity,but it would be modulated by the lightning channel conditions.The 17 RLER events showed 3 different time distribution patterns,namely,discrete,continuous,and discrete/continuous pulses,of which the discharge parameters were also different.The discrete pulse event had the longest duration,a small half-peak width,and a long interstroke time interval.Furthermore,all of these events occurred during the last several leader/return strokes.The continuous pulse event had a short duration and a small peak current.The discrete/continuous pulse event had a moderate duration and a large half-peak width and peak current.These three distinct time distribution patterns may be determined by different development types of lightning leaders.Our observations support the leader high-field runaway mechanism. | Xiong ZHANG Xiaoqiang LI Yang ZHANG Baofeng CAO Yi ZHENG Rubin JIANG Peng LI Hongbo ZHANG Weitao LYU | 2023 | Science China Earth Sciences2023，66，3： | 1 |
| 7 | Performance analysis of frequency‑mixed PPP‑RTK using low‑cost GNSS chipset with different antenna configurations显示文摘Low-cost Global Navigation Satellite System(GNSS)devices offer a cost-effective alternative to traditional GNSS systems,making GNSS technology accessible to a wider range of applications.Nevertheless,low-cost GNSS devices often face the challenges in effectively capturing and tracking satellite signals,which leads to losing the observations at certain frequencies.Moreover,the observation peculiarities of low-cost devices are in contradistinction to those of traditional geodetic GNSS receivers.In this contribution,a low-cost PPP-RTK model that considers the unique characteristics of different types of measurements is developed and its performance is fully evaluated with u-blox F9P receivers equipped with three distinctive antenna configurations:vertical dipole,microstrip patch,and helix antennas.Several static and kinematic experiments in different scenarios are conducted to verify the effectiveness of the proposed method.The results indicate that the mixed-frequency PPP-RTK model outperforms the traditional dual-frequency one with higher positioning accuracy and fixing percentage.Among the three low-cost antennas tested,the vertical dipole antenna demonstrates the best performance under static conditions and shows a comparable performance as geodetic antennas with a positioning accuracy of 0.02 m,0.01 m and 0.07 m in the east,north,and up components,respectively.Under low-speed kinematic scenarios,the helix antenna outperforms the other two with a positioning accuracy of(0.07 m,0.07 m,0.34 m).Furthermore,the helix antenna is also proved to be the best choice for vehicle navigation with an ambiguity fixing rate of over 95%and a positioning accuracy of(0.13 m,0.14 m,0.36 m). | Xingxing Li Hailong Gou Xin Li Zhiheng Shen Hongbo Lyu Yuxuan Zhou Hao Wang Qian Zhang | 2023 | Satellite Navigation2023，4，3： | 0 |
| 8 | Development of a low-frequency magnetic lightning mapping system(LFM-LMS)in North China:validation and preliminary results显示文摘A low-frequency magnetic lightning mapping system(LFM-LMS)was built during the SHAndong Triggered Lightning Experiment(SHATLE),based on continuous measurements of magnetic field radiation from lightning.The hardware and source-mapping techniques used by the LFM-LMS were introduced;both Monte Carlo simulations and the observation of rocket-triggered lightning examples were employed to examine the location accuracy and detection effectiveness of the LFM-LMS.We estimated that the system’s location accuracy about 100−200 m horizontally and~200 m vertically.A natural intra-cloud lightning flash and a rocket-triggered lightning flash,both with intricate structures and discharging processes,were examined using the three-dimensional mapping results.The progressing path of negative lightning leaders is usually well-defined,and its propagation speed is estimated to be(0.5−1.4)×10^(6)m/s.In summary,the LFM-LMS can reconstruct the three-dimensional morphology of lightning flashes;this technology provides a efficient method for investigating the characteristics of lightning development,as well as the overall electrical strucuture of thunderstorms. | Xiao Li GaoPeng Lu FanChao Lyu HongBo Zhang Kainat Qamar RuBin Jiang | 2023 | Earth and Planetary Physics2023，7，4： | 0 |
| 9 | Recent observations and research progresses of terrestrial gamma-ray flashes during thunderstorms显示文摘Terrestrial gamma-ray flashes(TGFs)are high-energy emissions in thunderstorms that were discovered first by satellite-based and then by ground-based gamma-ray detectors with photon energy up to tens of Me V.TGFs are a natural highenergy phenomenon associated with lightning discharges that frequently occur during thunderstorms.However,their production mechanisms and associated processes are still unclear.TGF studies have already been a research spotlight in the atmospheric electricity and high-energy atmosphere research areas.In this paper,we review recent research progresses on TGF studies in the past decade,including TGF detection,the relationship between TGFs and lightning processes,and thunderstorm activities.Several unsolved important scientific questions are discussed.Results suggest that upward TGFs observed by satellite-based detectors are closely connected with the development of in-cloud upward negative leaders.They are usually generated in milliseconds of the initiation of upward negative leaders and may produce a kind of distinct radio emissions because of the generation and propagation of huge amounts of high-energy electrons.By contrast,its counterpart,i.e.,downward TGFs observed by ground-based gamma-ray detectors,is associated with different types of lightning processes,such as downward negative or upward positive leaders,the initial continuing current stage of rocket-triggered lightning flashes return stroke processes.Because of limited observations,how these downward TGFs are generated is still unclear.Benefiting from the development of state-of-the-art instruments with high temporal and spatial resolutions,new insights into the processes and mechanisms of TGFs will be achieved with coordinated observations from satellite-based and ground-based measurements. | Fanchao LYU Yijun ZHANG Gaopeng LU Baoyou ZHU Hongbo ZHANG Wei XU Shaolin XIONG Weitao LYU | 2023 | Science China Earth Sciences2023，66，3： | 0 |
| 10 | Establishment and verification of prediction models for evaluating the physical and chemical properties of soilless substrates显示文摘In soilless culture,a suitable mixed substrate that provides a balanced and stable rhizosphere environment is vital for promoting plant growth.The present study was undertaken to establish seven prediction models of physical and chemical properties,including bulk density(DB),total porosity(TP),water-holding porosity(WHP),air porosity(AP),WHP/AP,electrical conductivity(EC)and cation exchange capacity(CEC)of mixed substrate based on regression equations of measured values from 76 substrate combinations.These seven models were verified using the measured values of 12 mixed substrates,and the average relative prediction errors(REs)were all less than 10%.A comprehensive property prediction model was established by weighted summation of the seven models of physical and chemical properties.According to the set values of DB,TP,WHP,AP,WHP/AP,EC and CEC,the comprehensive property model predicted the six mixture proportions of mixed-substrate,as verified using the measured values.This study is the first to establish prediction models for the physical and chemical properties of mixed substrates.The comprehensive property model could be used to evaluate the physical and chemical properties of commercial mixed substrates,and to provide the optimal mixture substrate formulations according to the setting property value of production requirement. | Binbin Gong Ning Wang Tiejun Zhang Shao Li Xiaolei Wu Jing Tian Jingrui Li Guiyun Lyu Hongbo Gao | 2021 | International Journal of Agricultural and Biological Engineering2021，14，2： | 0 |
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