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Enhanced baseline determination for formation flying LEOs by relative corrections of phase center and code residual variations

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Chinese Journal of Aeronautics 2022年第2期35卷 185-194页

作者： Bin YI Defeng GU bing ju Kai SHAO Houzhe ZHANG College of Liberal Arts and Sciences National University of Defense TechnologyChangsha 410073China TianQin Research Center for Gravitational Physics and School of Physics and Astronomy Sun Yat-sen University(Zhuhai Campus)Zhuhai 519082China National Key Laboratory of Science and Technology on Aerospace Flight Dynamics Beijing Aerospace Control CenterBeijing 100094China

Formation flying Low Earth Orbiters(LEOs)are important for implementing new and advanced concepts in Earth observation *** Baseline Determination(PBD)is a prerequisite for LEOs to complete specified mission *** is usually performed based on space-borne GNSS data,the relative corrections of phase center and code residual variations play crucial roles in achieving the best relative orbit ***,the influences of antenna Relative Phase Centre Variations(RPCVs)and Single-Difference(SD)Melbourne-Wu¨bbena(MW)Combination Residuals Variations(SD MWVs)on PBD are *** methods were tested using flight data from Gravity Recovery And Climate Experiment(GRACE)and GRACE Follow-On(GRACE-FO).Results showed that the maximum values for RPCVs and SD MWVs were 14 mm and 0.32 cycles,***,the RPCVs correction significantly enhanced the baseline accuracy;the K-Band Ranging(KBR)measurement consistency improved by 30.1%and 37.5%for GRACE and GRACE-FO,*** application of SD MWVs further improved the accuracy and reliability of PBD *** GRACE,the ambiguities fixing success rate increased from 85.1%to 97.9%and a baseline consistency of 0.57 mm was achieved for the KBR *** was found that the correction of both RPCVs and SD MWVs reduced the carrier phase observation minus computation residuals from double-difference ionosphere-free *** addition,in-flight data processing demonstrated that RPCVs and SD MWVs estimations for the current period could be used for the previous and subsequent periods.

关键词： Ambiguity resolution Formation flying Precise baseline determination(PBD) Relative phase centre variations(RPCVs)estimation SD MW combination residuals variations(SD MWVs)estimation

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Spaceborne GPS receiver antenna phase center offset and variation estimation for the Shiyan 3 satellite

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Chinese Journal of Aeronautics 2016年第5期29卷 1335-1344页

作者： Gu Defeng Lai Yuwang Liu junhong ju bing Tu Jia College of Sciences National University of Defense Technology

In determining the orbits of low Earth orbit （LEO） satellites using spaceborne GPS, the errors caused by receiver antenna phase center offset （PCO） and phase center variations （PCVs） are gradually becoming a major limiting factor for continued improvements to accuracy. Shiyan 3, a small satellite mission for space technology experimentation and climate exploration, was developed by China and launched on November 5, 2008. The dual-frequency GPS receiver payload delivers 1 Hz data and provides the basis for precise orbit determination within the range of a few centimeters. The antenna PCO and PCV error characteristics and the principles influencing orbit determination are analyzed. The feasibility of PCO and PCV estimation and compensation in different directions is demonstrated through simulation and in-flight tests. The values of receiver antenna PCO and PCVs for Gravity Recovery and Climate Experiment （GRACE） and Shiyan 3 satellites are estimated from one month of data. A large and stable antenna PCO error, reaching up to 10.34 cm in the z-direction, is found with the Shiyan 3 satellite. The PCVs on the Shiyan 3 satellite are estimated and reach up to 3.0 cm, which is slightly larger than that of GRACE satellites. Orbit validation clearly improved with independent k-band ranging （KBR） and satellite laser ranging （SLR） measurements. For GRACE satellites, the average root mean square （RMS） of KBR residuals improved from 1.01 cm to 0.88 cm. For the Shiyan 3 satellite, the average RMS of SLR residuals improved from 4.95 cm to 4.06 cm.

关键词： GRACE Phase center offset Phase center variations Shiyan 3 Spaceborne GPS

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Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination

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Chinese Journal of Aeronautics 2014年第5期27卷 1251-1258页

作者： Liu junhong Gu Defeng ju bing Yao Jing Duan Xiaojun Yi Dongyun College of Science National University of Defense Technology

The visibility for low earth orbit（LEO） satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system（GPS）. In addition, the spaceborne receivers＇ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satellites orbits. The precise orbit determination（POD） results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional（3D） accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about30 cm. As for the precise relative orbit determination（PROD）, the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demonstrates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit（GEO） satellites is illustrated for POD.

关键词： BeiDou-2 Geostationary earth orbit satellites Global positioning system Low earth orbit satellites Precise orbit determination Precise relative orbit determination

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Precise orbit determination for TH02-02 satellites based on BDS3 and GPS observations

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Chinese Journal of Aeronautics 2023年第5期36卷 475-485页

作者： Houzhe ZHANG bing ju Defeng GU Ying LIU Kai SHAO Xiaojun DUAN Zhiyong HUANG College of Science National University of Defense TechnologyChangsha 410073China National Key Laboratory of Science and Technology on Aerospace Flight Dynamics Beijing Aerospace Control CenterBeijing 100094China MOE Key Laboratory of TianQin Mission TianQin Research Center for Gravitational PhysicsFrontiers Science Center for TianQinCNSA Research Center for Gravitational WavesSun Yat-sen University(Zhuhai Campus)Zhuhai 519082China School of Artificial Intelligence Sun Yat-sen University(Zhuhai Campus)Zhuhai 519082China School of Physics and Astronomy Sun Yat-sen University(Zhuhai Campus)Zhuhai 519082China Information Engineering University Zhengzhou 450001China

The Tianhui-202(TH02-02)satellite formation,as a supplement to the microwave mapping satellite system Tianhui-201(TH02-01),is the first Interferometric Synthetic Aperture Radar(InSAR)satellite formation-flying system that supports the tracking of BeiDou global navigation Satellite system(BDS3)new B1C and B2a ***,the twin TH02-02 satellites also support the tracking of Global Positioning System(GPS)L1&L2 and BDS B1I&B3I *** the spaceborne receiver employs two independent boards to track the Global Navigation Satellite System(GNSS)satellites,we design an orbit determination strategy by estimating independent receiver clock offsets epoch by epoch for each GNSS to realize the multi-GNSS data fusion from different *** performance of the spaceborne receiver is evaluated and the contribution of BDS3 to the kinematic and reduced-dynamic Precise Orbit Determination(POD)of TH02-02 satellites is *** tracking data onboard shows that the average number of available BDS3 and GPS satellites are 8.7 and 9.1,*** carrier-to-noise ratio and carrier phase noise of BDS3 B1C and B2a signals are comparable to those of ***,strong azimuth-related systematic biases are recognized in the pseudorange multipath errors of B1C and *** pseudorange noise of BDS3 signals is better than that of GPS after eliminating the multipath errors from specific *** the GPS-based reduced-dynamic orbit with single-receiver ambiguity fixing technique as a reference,the results of BDS3-only and BDS3+GPS combined POD are *** Root Mean Square(RMS)of orbit comparison of BDS3-based kinematic and reduced-dynamic POD with reference orbit are better than 7 cm and 3 cm in three-Dimensional direction(3D).The POD performance based on B1C&B2a data is comparable to that based on B1I&*** precision of BDS3+GPS combined kinematic orbit can reach up to 3 cm(3D RMS),which has a more than 25%improvement relative to the GPS-only *** addi

关键词： BDS3 Multi-GNSS Precise orbit determination Spaceborne GNSS receiver TH02-02

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CO Clouds around SNR G21.8-0.6 and G32.8-0.1

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Chinese Journal of Astronomy and Astrophysics 2007年第5期7卷 705-711页

作者： Jian-jun Zhou Xi-Zheng Zhang Hong-Bo Zhang Jarken Esimbek ju-Yong Zhang bing-Gang ju National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 National Astronomical Observatories / Urumqi Observatory Chinese Academy of Sciences Urumqi 830011 Graduate School of Chinese Academy of Sciences Beijing 100049 Qinghai Station of Purple Mountain Observatory Chinese Academy of Sciences Delingha 817000

We made the first CO（1-0） mapping to SNR G21.8-0.6 and SNR G32.8-0.1, both associated with OH 1720MHz maser. Based on the morphological correspondence and velocity and position agreement between the radio remnant an... 详细信息

关键词： ISM clouds -- ISM individual (G21.8-0.6, G32.8-0.1 ) -- ISM molecules -- masers -- supernova remnants

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Characterization of Some Calcareous Soils from Henan and Their Proposed Classification in Chinese Soil Taxonomy

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Pedosphere 2017年第4期27卷 758-768页

作者： ju bing WU Kening ZHANG Ganlin David G. ROSSITER LI Ling School of Land Science and Technology China University of GeosciencesBeijing 100083China State Key Laboratory of Soil and Sustainable Agriculture.institute of Soil Science Chinese Academy of SciencesNanjing 210008China Section of Soil and Crop Sciences Cornell UniversityIthacaNY 14850USA College of Resources and Environmental Sciences Henan Agricultural UniversityZhengzhou 450000China

Calcareous soils are those soils containing layers of carbonate accumulation formed by either secondary accumulation or inheritance of CaCO_3 from calcareous parent *** soils are widely distributed in arid,semi-arid and even some humid climate ***,in the Chinese Soil Taxonomy(CST,3rd version),the soils that contain large amounts of CaCO_3 but do not meet requirements of Aridosols are classified as Hapli-Ustic *** group also includes many non-calcareous soils and those soils strongly affected by secondary carbonate accumulation together with quite dissimilar soils in terms of their morphology and *** study was conducted to determine calcification patterns and calcic processes occurring in representative pedons of calcareous soils in northwestern Henan Province,China and to classify these soils in CST.A Calcic subgroup was proposed to add within the Hapli-Ustic Cambosols.A diagnostic key was also provided to separate this subgroup from the Typic *** this way the different calcification degrees of soils were better reflected in the classification,which should lead to more uniform interpretive groups for better soil management.

关键词： calcic evidence, Calcic Hapli-Ustic Cambosols, calcic horizon, calcification, hypercalcic horizon, parent material

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Evidence of Evolution in the Dense Cores in Massive Star Forming Regions

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Chinese Journal of Astronomy and Astrophysics 2005年第4期5卷 363-370页

作者： Jian-jun Zhou Jarken Esimbek Ji-Xian Sun bing-Gang ju Jing-Jiang Sun National Astronomical Observatories/Urumqi observatory Chinese Academy of SciencesUrumqi 830011 Graduate School of the Chinese Academy of Science Beijing 100080 Qinghai Station of Purple mountain Observatory Chinese Academy of Science DelinghaQinghai 817000

The excitation of H2O masers usually needs very high density gas,hence it can serve as a marker of dense gas in HⅡ region. We selected a sample of H2O maser sources from Plume et al. （four with, and four without detected CS（J = 7 - 6） emission）, and observed them in ^13CO（J=1-0） and C^18O （J=1-0）. C^18O （J=1-0） emission was detected only in three of the sources with detected CS（J=7-6） emission. An analysis combined with some data in the literature suggests that these dense cores may be located at different evolutionary stages. Multi-line observation study may provide us clues on the evolution of massive star forming regions and the massive stars themselves.

关键词： ISM: molecules - masers - radio lines: ISM-stars: formation

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Mapping Soil Organic Carbon Stocks of Northeastern China Using Expert Knowledge and GIS-based Methods

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Chinese Geographical Science 2017年第4期27卷 516-528页

作者： SONG Xiaodong LIU Feng ju bing ZHI junjun LI Decheng ZHAO Yuguo ZHANG Ganlin State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

The main aim of this paper was to calculate soil organic carbon stock(SOCS) with consideration of the pedogenetic horizons using expert knowledge and GIS-based methods in northeastern China.A novel prediction process was presented and was referred to as model-then-calculate with respect to the variable thicknesses of soil horizons(MCV).The model-then-calculate with fixed-thickness(MCF),soil profile statistics(SPS),pedological professional knowledge-based(PKB) and vegetation type-based(Veg) methods were carried out for *** respect to the similar pedological information,nine common layers from topsoil to bedrock were grouped in the *** results suggested that the MCV method generated better performance than the other methods *** the comparison of polygon based approaches,the Veg method generated better accuracy than both SPS and PKB,as limited soil data were *** prediction of the pedogenetic horizons within MCV benefitted the regional SOCS estimation and provided information for future soil classification and understanding of soil *** intermediate product,that is,horizon thickness maps were fluctuant enough and reflected many details in *** linear mixed model indicated that mean annual air temperature(MAAT) was the most important predictor for the SOCS *** minimal residual of the linear mixed models was achieved in the vegetation type-based model,whereas the maximal residual was fitted in the soil type-based *** 95% of SOCS could be found in Argosols,Cambosols and *** largest SOCS was found in the croplands with vegetation of Triticum aestivum L.,Sorghum bicolor(L.) Moench,Glycine max(L.) Merr.,Zea mays *** Setaria italica(L.) ***.

关键词： soil organic carbon stock model-then-calculate random forest linear mixed model northeastern China

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Changes in starch quality of mid-season indica rice varieties in the lower reaches of the Yangtze River in last 80 years

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Journal of Integrative Agriculture 2020年第12期19卷 2983-2996页

作者： ZHANG Hao JING Wen-jiang XU Jing-ju MA bing-ju WANG Wei-lu ZHANG Wei-yang GU jun-fei LIU Li-jun WANG Zhi-qin YANG Jian-chang Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops Yangzhou UniversityYangzhou 225009P.R.China

Rice (Oryza sativa L.) quality depends mainly on the characteristics of starch stored in kernels. Understanding the changes in starch characteristics in kernels during variety improvement would have great significance to improve rice quality. This study was designed to investigate the starch characteristics in the kernels and associated physiological traits of indica rice varieties in the lower reaches of the Yangtze River in China in last 80 years. Eight representative mid-season indica rice varieties were grown in the field. The results showed that the grain yield was significantly increased with the improvement of varieties and such an increase was mainly attributed to the increase in total number of spikelets. The tall varieties applied in the 1940s–1950s had higher protein content, relative crystallinity and infrared (IR) ratio of 1 045/1 022 cm^–1. The semi-dwarf varieties applied in the 1980s–1990s had higher gel consistency, amylopectin content, IR ratio of 1 022/995 cm^–1, and breakdown value. With the improvement of varieties, the amylose content, large-sized starch granule number and volume distribution, onset and peak of gelatinization temperature, gelatinization and retrogradation enthalpy, setback value, pasting temperature, viscosity of peak, hot and final, and 1-aminocycopropane-1-carboxylic acid (ACC) concentrations in panicles and root bleeding were gradually decreased, whereas the medium-sized starch granule number and volume distribution, activities of key enzymes in grains, and zeatin (Z)+zeatin riboside (ZR) contents in panicles and root bleeding at grain filling stage were gradually increased. Correlation analysis showed that starch thermodynamic characteristics were closely related to starch structure and components, key enzymes and hormones. The results suggest that starch quality was enhanced through the optimization of starch components, structure, thermodynamics, and the regulation of key enzymes in grains and hormones in panicles and roo

关键词： rice starch thermodynamics hormone variety improvement

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Single-center report of 5-year follow-up on 94 patients underwent transmyocardial laser revascularization

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Chinese Medical Journal 2007年第22期120卷 1982-1985页

作者： QU Zheng ZHENG ju-bing ZHANG Zhao-guang Department of Cardiac Surgery Beijing Anzhen Hospital Capital Medical University Beijing 100029 China

Background Transmyocardial laser revascularization （TMLR） has been used in the treatment of patients with end-stage coronary artery disease （CAD） since 1990. The aim of this study was to evaluate the long-term effectiveness of TMLR in patients with diffuse CAD.Methods Ninety-four consecutive patients underwent TMLR in one center from july 1997 to December 2000. The follow-up data of these patients were obtained through face-to-face, mail questionnaires, or telephone interviews in july 2004 and December 2004. Four cases failed to respond. Mean follow-up time was （5.5±1.0） years. Results Mean Canadian Cardiovascular Society （CCS） angina scores of TMLR patients were 3.1±0.8 at baseline, 1.7±0.9 at 1 year （P〈0.05）, 1.7±0.9 at 3 years （P〈0.05）, and 1.9±0.9 at 5 years （P〈0.05）. At an average of 5 years, 69% of the patients had 〉 1 angina class reduction, mean NYHA class level （1.9±0.9） ameliorated compared to the baseline （2.5±0.7, P〈0.001）, the rate of re-hospitalization was 2.7 times/person. Kaplan-Meier survival rate was 87% at 1 year, 69% at 3 years and 64% at 5 years. The causes of death were attributed more to heart failure （58.9%） and myocardial infraction （14.7%） after TMLR. The patients with no angina relief, or who died after TMLR, had a higher percentage of preoperative unstable anginas or prior myocardial infraction compared to the survivors. The assorted shapes of myocardial laser channels were detected in some patients by the color Doppler velocity technique. Conclusions TMLR provided a long-term improvement in the quality of life, including CCS angina class or NYHA heart functional class for about 70% of Chinese patients with severely disabling angina pectoris. The various myocardial laser channels would always be visible after TMLR. 5-years after TMLR as a sole therapy, the survival rate of the patients was 64%.

关键词： transmyocardial laser revascularization angina coronary artery disease

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