检索结果-南通市图书馆

Inter-satellite link augmented BeiDou-3 orbit determination for precise point positioning

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第4期35卷 332-343页

作者： Liqian ZHAO Xiaogong HU Chengpan TANG Shanshi ZHOU yueling cao Qianxin WANG Ranran SU Space Star Technology Co. Ltd.Beijing 100095China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Environment Science and Spatial Informatics China University of Mining and TechnologyXuzhou 221116China Beijing Satellite Navigation Center Beijing 100094China

Precise Point Positioning(PPP) requires precise products, including high-accuracy satellite orbit and clock parameters. It is impossible to obtain an orbit solution that is sufficiently accurate for PPP services with a regional tracking network;therefore, satellite orbits are usually estimated by a global tracking network with a large number of ground stations. However, it is expensive to build globally distributed stations. Fortunately, BeiDou-3 satellites carry an InterSatellite Link(ISL) payload, which can track the whole arc of the BeiDou-3 satellites and enhance the orbit determination accuracy with regional ground stations. In this contribution, a novel orbit determination strategy for BeiDou-3 PPP is proposed, in which the BeiDou-3 satellite orbits are enhanced by the ISL. First, the generation of precise satellite products is demonstrated in *** addition, the products are assessed by Satellite Laser Ranging(SLR) residuals and overlap comparisons. Moreover, the products are used for receivers in China's Mainland to carry out the static and kinematic modes to research the PPP performance of Bei Dou-3’s 3IGSO/24MEO *** SLR validations of the satellite orbits demonstrate an accuracy better than 0.1 m in the radial component, and the orbit overlap comparisons show accuracies of 0.016 m in the radial component,0.088 m in the along-track component and 0.087 m in the cross-track component. The Standard Deviation(STD) in the differences in overlapping arcs for the estimated satellite clocks is approximately 0.10 ns. The static PPP results demonstrate that the error in both the horizontal and vertical components is smaller than 10 cm after 30 minutes of convergence. After 24 hours of convergence,the errors are 0.70 cm, 0.63 cm and 1.99 cm for the north, east and up components, *** kinematic PPP experiment illustrates that the Root Mean Square(RMS) position errors in the north, east and up components are approximately 3.23 cm, 5.27 cm a

关键词： BeiDou-3 Clock offsets Convergence Inter-satellite link Precise Point Positioning Regional ground stations Satellite orbits

Multipath error detection and correction for GEO/IGSO satellites

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2012年第7期55卷 1297-1306页

作者： WU XiaoLi ZHOU JianHua WANG Gang HU XiaoGong cao yueling Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030China Beijing Global Information Application and Development Center Beijing 100094China

Constellations of regional satellite navigation systems are usually constituted of geostationary satellites (GEO) and inclined geostationary satellites (IGSO) for better service availability. Analysis of real data shows that the pseudorange measurements of these two types of satellites contain significant multipath errors and code noise, and the multipath for GEO is extremely serious, which is harmful to system services. In contrast, multipath error of carrier phase measurements is less than 3 cm, which is smaller than the multipath of pseudorange measurements by two orders of magnitude. Using a particular combination of pseudorange and dual-frequency carrier phase measurements, the pseudorange multipath errors are detected, and their time varying features are analyzed. A real-time multipath correction algorithm is proposed in this paper, which is called CNMC (Code Noise and Multipath Correction). The algorithm decreases the influence of the multipath error and therefore ensures the performance of the system. Data processing experiments show that the multipath error level may be reduced from 0.5 m to 0.15 m by using this algorithm, and 60% of GEO multipath errors and 42% of IGSO multipath errors are successfully corrected with CNMC. Positioning experiments are performed with a constellation of 3 GEO plus 3 IGSO satellites. For dual-frequency users the East-West position accuracy is improved from 1.31 m to 0.94 m by using the CNMC algorithm, the South-North position accuracy is improved from 2.62 m to 2.29 m, and the vertical position accuracy is improved from 4.25 m to 3.05 m. After correcting multipath errors, the three-dimensional position accuracy is improved from 5.16 m to 3.94 m.

关键词： multipath error carrier smoothing pseudorange GEO satellite position error

Insight into Ce Doping Induced Oxygen Vacancies over Ce-Doped MnO2 Catalysts for Imine Synthesis

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2020年第11期38卷 1353-1359页

作者： Haidong Shen Jun Bu Wenbin Wang Chen Wu yueling cao Baoliang Zhang Qiuyu Zhang Hepeng Zhang Laboratory of Special Functional&Smart Polymer Materials School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi'anShaanxi 710129China

of main observation and conclusion The pursuit of modern sustainable chemistry has stimulated the development of innovative catalytic processes that enable chemical transformations to be performed under mild and clean conditions with high ***,an amorphous sheet-like MnO2(Ce-doped MnO2:CMBO)was obtained after Ce doping,which exhibits excellent catalytic performance for the oxidation coupling of alcohol and *** of 99%and a selectivity of 99%could be achieved within 6 h at 60℃under air atmosphere,and the formation rate of target product was up to 30.2 nmol h^-1·m^-*** on a series of characterizations,it was found that the doping of Ce into the MnO2 could increase the concentration of the oxygen vacancies,thus forming abundant active surface oxygen species and favoring the mobility of lattice oxygen,which are the main reasons for the greatly enhanced catalytic performance of *** work indicates that increasing oxygen vacancy by element doping may serve as a facile and effcient way to enhance catalytic performance of transition metal oxide.

关键词： doping Oxygen aniline

Identifying the roles of Ce^(3+)-OH and Ce-H in the reverse water-gas shift reaction over highly active Ni-doped CeO_(2) catalyst

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第7期15卷 5831-5841页

作者： Haidong Shen Yujuan Dong Shaowei Yang Yuan He Qimeng Wang yueling cao Wenbin Wang Tianshuai Wang Qiuyu Zhang Hepeng Zhang Xi’an Key Laboratory of Functional Organic Porous Materials School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710129China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China

Nickel-CeO_(2)-based materials are commonly used for the thermal catalytic hydrogenation of CO_(2).However,high Ni loadings and low CO selectivity restrict their use in the reverse water–gas shift(RWGS)***,we demonstrate a highly active,robust,and low-Ni-doped(1.1 wt.%)CeO_(2) catalyst(1.0-Ni-CeO_(2)).The Ni-based-mass-specific CO formation rate reaches up to 1,542 mmol·gNi^(−1)·h^(−1) with 100%CO selectivity at 300°C for 100 h,among the best values reported in the *** functional theory(DFT)and diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)results reveal that the enhanced catalytic activity is attributed to the abundant Ce–H species,while the high selectivity results from low CO *** importantly,a new reaction mechanism is proposed,which involves the reduction of bicarbonate to generate formate intermediate and CO by the H−released from Ce–H *** new findings in this work will benefit the design of economic,efficient,and robust catalysts for low-temperature RWGS reactions.

关键词： CO_(2)hydrogenation Ni-doped CeO_(2) reverse water-gas shift(RWGS)reaction cerium hydride mechanism investigation

Forecast of equivalent clock correction and its application

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Forecast of equivalent clock correction and its application

Positioning accuracy assessment for the 4GEO/5IGSO/2MEO constellation of COMPASS

第五届中国卫星导航学术年会

作者： XING Nan HU Xiaogong cao yueling SU Ranran WU Xiaoli Beijing Research Institute of Telemetry Shanghai Astronomical Observatory Chinese Academy of Sciences Beijing Global Information Center of Application and Exploitation

ISBN: (纸本)9783642547393

Beidou Navigation Satellite System provides two kinds of services: basic navigation service and wide area differential service. To enhance the positioning accuracy, both services are challenged by orbit error reduction problem, especially during yaw‐steering mode. Besides basic information, additional parameters, such as satellite pseudorange differential correction, could efficiently correct satellite orbit error and clock error. However, since it needs to be calculated in real‐time, differential correction is only broadcast to authorized users. Through investigation of the historical record, we find that shortly （an hour） forecasting for differential correction is doable. We proposed two forecasting methods in this work, and tested them with real observation data. We find that positioning precision of basic navigation service could be efficiently improved with the forecasted differential correction, in some cases could even reach the level of wide area differential service.

关键词： Beidou Navigation Satellite System satellite pseudorange differential correction positioning accuracy

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2012年第12期55卷 2290-2299页

作者： ZHOU ShanShi cao yueling ZHOU JianHua HU XiaoGong TANG ChengPan LIU Li GUO Rui HE Feng CHEN JunPing WU Bin Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Beijing Global lnformation Application and Development Center Beijing 100094China

Determined to become a new member of the well-established GNSS family,COMPASS(or BeiDou-2) is developing its capabilities to provide high accuracy positioning *** positioning modes are investigated in this study to assess the positioning accuracy of COMPASS' 4GEO/5IGSO/2MEO *** Point Positioning(PPP) for geodetic users and real-time positioning for common navigation users are *** evaluate PPP accuracy,coordinate time series repeatability and discrepancies with GPS' precise positioning are *** show that COMPASS PPP repeatability for the east,north and up components of a receiver within China's Mainland is better than 2 cm,2 cm and 5 cm,*** systematic offsets of several centimeters exist between COMPASS precise positioning and GPS precise positioning,indicating errors remaining in the treatments of COMPASS measurement and dynamic models and reference frame differences existing between two *** common positioning users,COMPASS provides both open and authorized services with rapid differential corrections and integrity information available to authorized *** assessment shows that in open service positioning accuracy of dual-frequency and single-frequency users is about 5 m and 6 m(RMS),respectively,which may be improved to about 3 m and 4 m(RMS) with the addition of differential *** accurate Signal In Space User Ranging Error(SIS URE) and Geometric Dilution of Precision(GDOP) contribute to the relatively inferior accuracy of COMPASS as compared to *** the deployment of the remaining 1 GEO and 2 MEO is not able to significantly improve GDOP,the performance gap could only be overcome either by the use of differential corrections or improvement of the SIS URE,or both.

关键词： PPP real-time positioning authorized services orbit determination

The wide-area difference system for the regional satellite navigation system of COMPASS

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2012年第7期55卷 1307-1315页

作者： cao yueling HU XiaoGong WU Bin ZHOU ShanShi LIU Li SU RanRan CHANG ZhiQiao HE Feng ZHOU JianHua Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Graduate University of Chinese Academy of Seiences Beijing 100049 China Beijing Global Information Application and Development Center Beijing 100094 China

The regional satellite navigation system of COMPASS (Phase I) provides both open services and authorized services. Authorized services offer differential corrections and integrity information to users to support higher positioning, navigation and timing precision. Experimenting with real data, positioning accuracy is estimated with a 3GEO/4IGSO COMPASS constellation. The results show that with dual-frequency and single-frequency pseudo-range measurements, the positioning errors are respectively 8 and 10 m (RMS) for open service users, while for authorized users, the errors are 4 and 5 m (RMS), respectively. The COMPASS constellation geometry may cause large error to occur in the height component by 7-9 m for dualor single-frequency users, which can be effectively reduced with the differential corrections supplied by the authorized services. Multipath errors are identified and corrected for COMPASS, resulting in 25% positioning accuracy improvement for dual-frequency users and 10% improvement for single-frequency users.

关键词： COMPASS equivalent satellite clock error ionospheric grid multipath error positioning error

Orbit determination and time synchronization for a GEO/IGSO satellite navigation constellation with regional tracking network

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2011年第6期54卷 1089-1097页

作者： ZHOU ShanShi HU XiaoGong WU Bin LIU Li QU WeiJing GUO Rui HE Feng cao yueling Wu XiaoLi ZHU LingFeng SHI Xin TAN HongLi Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Graduate University of Chinese Academy of Sciences Beijing 100049China Beijing Global Information Application and Development Center Beijing 100094China

Aiming at regional services,the space segment of COMPASS (Phase I) satellite navigation system is a constellation of Geostationary Earth Orbit (GEO),Inclined Geostationary Earth Orbit (IGSO) and Medium Earth Orbit (MEO) *** orbit determination (POD) for the satellites is limited by the geographic distribution of regional tracking *** time synchronization (TS) system is developed to supplement the regional tracking network,and satellite clock errors and orbit data may be obtained by simultaneously processing both tracking data and TS ***,inconsistency between tracking system and TS system caused by remaining instrumental errors not calibrated may decrease navigation *** the other hand,POD for the mixed constellation of GEO/IGSO/MEO with the regional tracking network leads to parameter estimations that are highly *** example of correlation is found between GEO's orbital elements and its clock *** estimate orbital elements and clock errors for a 3GEO+2IGSO constellation in this study using a multi-satellite precise orbit determination (MPOD) strategy,with which clock error elimination algorithm is applied to separate orbital and clock estimates to improve numerical *** Laser Ranging (SLR) data are used to evaluate User Ranging Error (URE),which is the orbital error projected on a receiver's line-of-sight ***-way radio-wave time transfer measurements are used to evaluate clock *** with data from the regional tracking network,we conclude that the fitting of code data is better than 1 m in terms of Root-Mean-Square (RMS),and fitting of carrier phase is better than 1 *** orbital evaluation,difference between computed receiver-satellite ranging based on estimated orbits and SLR measurements is better than 1 m (RMS).For clock estimates evaluation,2-hour linear-fitting shows that the satellite clock rates are about 1.E-10 s/s,while receiver clock rates a

关键词： POD time synchronization clock errors elimination SLR evaluation

Kinematic Wide Area Differential Corrections for BeiDou Regional System basing on two-way Time Synchronization

在线全文

学校读者我要写书评

暂无评论

Kinematic Wide Area Differential Corrections for BeiDou Regi...