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| 1 | Orbit determination and time synchronization for a GEO/IGSO satellite navigation constellation with regional tracking network显示文摘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) satellites.Precise orbit determination (POD) for the satellites is limited by the geographic distribution of regional tracking stations.Independent 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 data.Consequently,inconsistency between tracking system and TS system caused by remaining instrumental errors not calibrated may decrease navigation accuracy.On the other hand,POD for the mixed constellation of GEO/IGSO/MEO with the regional tracking network leads to parameter estimations that are highly correlated.Notorious example of correlation is found between GEO's orbital elements and its clock errors.We 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 efficiency.Satellite 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 direction.Two-way radio-wave time transfer measurements are used to evaluate clock errors.Experimenting 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 cm.For 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 are about 1×10 13-1×10 12 s/s.For the 72-hour POD experiment,the average differences between POD satellite clock rates estimates and clock measurements based on TS system are about 1×10 13 s/s,and for receiver clock rates,the differences are about 1×10 15 s/s. | ZHOU ShanShi HU XiaoGong WU Bin LIU Li QU WeiJing GUO Rui HE Feng CAO YueLing Wu XiaoLi ZHU LingFeng SHI Xin TAN HongLi | 2011 | Science China(Physics,Mechanics & Astronomy)2011，54，6： | 44 |
| 2 | Multipath error detection and correction for GEO/IGSO satellites显示文摘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. | WU XiaoLi ZHOU JianHua WANG Gang HU XiaoGong CAO YueLing | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，7： | 31 |
| 3 | Positioning accuracy assessment for the 4GEO/5IGSO/2MEO constellation of COMPASS显示文摘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 services.Two positioning modes are investigated in this study to assess the positioning accuracy of COMPASS' 4GEO/5IGSO/2MEO constellation.Precise Point Positioning(PPP) for geodetic users and real-time positioning for common navigation users are utilized.To evaluate PPP accuracy,coordinate time series repeatability and discrepancies with GPS' precise positioning are computed.Experiments 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,respectively.Apparent 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 systems.For common positioning users,COMPASS provides both open and authorized services with rapid differential corrections and integrity information available to authorized users.Our 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 corrections.Less 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 GPS.Since 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. | ZHOU ShanShi CAO YueLing ZHOU JianHua HU XiaoGong TANG ChengPan LIU Li GUO Rui HE Feng CHEN JunPing WU Bin | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，12： | 31 |
| 4 | The wide-area difference system for the regional satellite navigation system of COMPASS显示文摘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. | CAO YueLing HU XiaoGong WU Bin ZHOU ShanShi LIU Li SU RanRan CHANG ZhiQiao HE Feng ZHOU JianHua | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，7： | 21 |
| 5 | Species-dependent neuropathology in transgenic SOD' aigs显示文摘 | Huaqiang Yang Guohao Wang Haitao Sun Runzhe Shu Tao Liu Chuan-En Wang Zhaoming Liu Yu Zhao Bentian Zhao Zhen Ouyang Dongshan Yang Jiao Huang Yueling Zhou Shihua Li Xiaodan Jiang Zhicheng Xiao Xiao-Jiang Li Liangxue Lai | 2014 | Cell Research2014，24，4： | 13 |
| 6 | Geological Structure and Quaternary Activity of the Zhangjiakou Fault, Northern China显示文摘Based on detailed field investigations,this paper describes the geometrical characteristics and tectonic activities of the Zhangjiakou fault at the northwest of Beijing. This fault strikes mainly northwest to west,short parts of which strike near east to west,dipping north,and extends over a length of 70km. It is a major geological and geomorphological margin,controlling the neotectonic movement in this region. On the south side of the Zhangjiakou fault are the Late Quaternary unconsolidated deposits,forming basins; while on the other side are Mesozoic volcano debris and Pre-Mesozoic metamorphic rocks, forming lower mountains and hills. The Zhangjiakou fault consists mainly of high-angle inverse strike-slip fault and partially of normal strike-slip fault. Among these,the north-dipping NW-NWW-trending secondary faults,constituting the main fracture of the fault,have inverse characteristics; those near the EW-trending secondary faults are links of the former faults,with a smaller length and normal faulting characteristics. Thus,the Zhangjiakou fault is a north-dipping inverse and partially south-dipping normal strike-slip fault. The Zhangjiakou fault has been continuously active since the Quaternary. With the exception of the western end extension,which has been active since the late Pleistocene, the main part of the fault has been active since the Holocene. The central main segment of the Zhangjiakou fault is more active. Since the mid-late period of the late Pleistocene,the average vertical slip rate of a single fault has been over 0. 07mm /a ~ 0. 30mm /a. The Zhangjiakou fault has multi-slip surfaces,and the total vertical slip rate reaches 1. 33mm /a,estimated from the Qingshuihe river terraces and the relevant drilling data. | Zhou Yueling You Huichuan Zhou Jianglin Shao Cuiru Zhang Zhengyu | 2011 | Earthquake Research in China2011，25，1： | 0 |
| 7 | Signal-in-space accuracy for BeiDou navigation satellite system:Challenges and solutions显示文摘Service accuracy of global navigation satellite system(GNSS)is determined by satellite constellation,signal-in-space(SIS)accuracy and signal transmission errors.The State Council Information Office of the People's Republic of China issued China's BeiDou Navigation Satellite System(BDS)White Paper(www.beidou.gov.cn/fbh2016.html)on Jun.16th 2016,which notes that,BDS takes a three-step development strategy,from domestic service,through Asia-Pacific regional service,to global service,and features mixed constellation of Geostationary Earth Orbit(GEO),Inclined Geostationary Earth Orbit(IGSO)and | ShanShi Zhou Bin Wu XiaoGong Hu YueLing Cao Yang Yu | 2017 | Science China(Physics,Mechanics & Astronomy)2017，60，1： | 0 |
| 8 | Geometric Structure and Tectonic Activities of Wanquan Fault,Hebei Province显示文摘Based on detailed investigations and prospecting,this paper describes the geometrical characteristics and tectonic activities of Wanquan fault in northwest of Beijing. This fault strikes mainly northeast or northeast to north,dipping southeast,and extends over a length of 15km. It is a major geological and geomorphological margin,controlling the neotectonic movement in this region. On the southeast side of Wanquan fault are the Late Quaternary unconsolidated deposits,forming a basin or deposition; but on the other side is Mesozoic volcano debris,forming lower-mountains and hills. Wanquan fault is a mid- to-high-angle normal fault dipping southeast. This fault was more active in the Quaternary. Since the middle-late part of the alate Pleistocene,the average rate with vertical slip of a single fault is over 0. 03 ~ 0. 3mm /a,but the fault has multiple slipping surfaces,and a total rate with vertical slip will be estimated. | Zhou Jianglin You Huichuan Zhou Yueling Shao Cuiru Yang Qiyan Li Jinjin Zhang Zhengyu | 2013 | Earthquake Research in China2013，27，2： | 0 |
| 9 | Solving multiple travelling salesman problem through deep convolutional neural network显示文摘The multiple travelling salesman problem(mTSP)is a classical optimisation problem that is widely applied in various fields.Although the mTSP was solved using both classical algorithms and artificial neural networks,reiteration is inevitable for these methods when presented with new samples.To meet the online and high-speed logistics requirements deploying new information technology,the iterative algorithm may not be reliable and timely.In this study,a deep convolutional neural network(DCNN)-based solution method for mTSP is proposed,which can establish the mapping between the parameters and the optimal solutions directly and avoid the use of iterations.To facilitate the DCNN in establishing a mapping,an image representation that can transfer the mTSP from an optimisation problem into a computer vision problem is presented.While maintaining the excellent quality of the results,the efficiency of the solution achieved by the proposed method is much higher than that of the traditional optimisation method after training.Meanwhile,the method can be applied to solve the mTSP under different constraints after transfer learning. | Zhengxuan Ling Yueling Zhou Yu Zhang | 2023 | IET Cyber-Systems and Robotics2023，5，1： | 0 |
| 10 | Unraveling the reaction reversibility and structure stability of nickel sulfide anodes for lithium ion batteries显示文摘The electrochemical performance of lithium-ion batteries,i.e.specific capacity and cyclability,is primarily determined by chemical reversibility and structural stability of the electrodes in cycling.Here we have investigated the fundamental reaction behaviors of nickel sulfide(NixSy)as lithium-ion battery anodes by in-situ TEM.We find that Ni_(3)S_(2)is the electrochemically stable phase,which appears in the first cycle of the NixSyanode.From the second cycle,conversion between Ni_(3)S_(2)and Li_(2)S/Ni is the dominant electrochemical reaction.In lithiation,the NixSynanoparticles evolve into a mixture of Ni nanocrystals embedded in Li_(2)S matrix,which form a porous structure upon full lithiation,and with the recrystallization of the Ni_(3)S_(2)phase in delithiation,a compact and interconnected network is built.Structural stability in cycles is susceptible to particle size and substrate restraint.Carbon substrate can certainly improve the tolerance for size-dependent pulverization of NixSynanoparticles.When NixSynanoparticle exceeds the critical size value,the morphology of the particle is no longer well maintained even under the constraints of the carbon substrate.This work deepens the understanding of electrochemical reaction behavior of conversiontype materials and helps to rational design of high-energy density battery anodes. | Yu Huang Chunyuan Liang Yueling Cai Yi Zhou Bingkun Guo Jipeng Cheng Heguang Liu Peng Wang Qianqian Li Anmin Nie Hongtao Wang Jinsong Wu Tongyi Zhang | 2023 | Journal of Energy Chemistry2023，，5： | 0 |
| 11 | Inter-satellite link augmented BeiDou-3 orbit determination for precise point positioning显示文摘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 detail.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 constellation.The 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, respectively.The 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 and 8.64 cm, respectively,after convergence. The obtainable positioning and convergence performances are comparable to those using products generated by global tracking networks. | Liqian ZHAO Xiaogong HU Chengpan TANG Shanshi ZHOU Yueling CAO Qianxin WANG Ranran SU | 2022 | Chinese Journal of Aeronautics2022，35，4： | 0 |
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