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A virtual reference satellite differential method for relative correction of satellite ephemeris errors

Science china(Physics,Mechanics & Astronomy) 2010年第12期53卷 2300-2306页

作者： CAI ChengLin 1.3 , LI XiaoHui 2,3 & WU HaiTao 2,3 1.Gulin University of Electronic Technology, 541.04, china 2 National {1. service center, chinese academy of sciences, lintong 71.600, china 3 Key Laboratory of Precision Navigation and Timing Technology, National {1. service center, chinese academy of sciences, lintong 71.600, china 1. Gulin University of Electronic Technology Gulin 541004 China3. Key Laboratory of Precision Navigation and Timing Technology National Time Service Center Chinese Academy of Sciences Lintong 710600 China2. National Time Service Center Chinese Academy of Sciences Lintong 710600 China

In order to solve the problems that the novel wide area differential method on the satellite clock and ephemeris relative correction (CERC) in the non-geostationary orbit satellite constellation, a virtual reference satellite (VRS) differential principle using relative correction of satellite ephemeris errors is proposed. It is referred to be as the VRS differential principle, and the elaboration is focused on the construction of pseudo-range errors of VRS. Through qualitative analysis, it can be found that the impact of the satellite’s clock and ephemeris errors on positioning can basically be removed and the users’ positioning errors are near zero. Through simulation analysis of the differential performance, it is verified that the differential method is universal in all kinds of satellite navigation systems with geostationary orbit (GEO) constellation, Medium orbit (MEO) constellation or hybrid orbit constellation, and it has insensitivity to abnormal aspects of a satellite ephemeris and clock. Moreover, the real time positioning accuracy of differential users can be maintained within several decimeters after the pseudo-range measurement noise is effectively weakened or eliminated.

关键词： wide area differential method virtual reference satellite (VRS) satellite ephemeris errors satellite clock errors constellation

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Performance and Application of Double-layered Microcapsule Corrosion Inhibitors

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Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 845-853页

作者：余海燕 WANG Yingxiang WANG Ruizhi HU lintong WANG Tianlei School of Materials Science and Engineering Tianjin Chengjian UniversityTianjin 300384China Tianjin Key Laboratory of Building Green Functional Materials Tianjin Chengjian UniversityTianjin 300384China

Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying *** protection by the outer capsule wall was used to prolong the service life of the corrosion *** dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate *** microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were *** experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely *** microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1.day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely *** mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 *** incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.

关键词： corrosion inhibitors microcapsule double-layer structure potentiodynamic polarization curve

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An analysis of the wide area differential method of geostationary orbit satellites

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Science china(Physics,Mechanics & Astronomy) 2009年第2期52卷 310-314页

作者： CAI ChengLin1.2,3?, LI XiaoHui1.& WU HaiTao1.1.National time {1. center, chinese academy of sciences, lintong 71.600, china 2 Hunan Institute of Humanities, Science and Technology, Loudi 41.000, china 3 Graduate University of chinese academy of sciences, Beijing 1.0049, china 1. National time {1. center Chinese Academy of Sciences Lintong 710600 China 2. Hunan Institute of Humanities Science and Technology Loudi 417000 China 3. Graduate University of chinese academy of sciences Beijing 100049 China

This work aims to obtain a wide area differential method for geostationary orbit (GEO) constellation. A comparison between the dilution of precision (DOP) of four-dimensional (4D) calculation including sa- tellite clock errors and ephemeris errors and that of three-dimensional (3D) calculation only including ephemeris errors with the inverse positioning theory of GPS shows the conclusion that all the 3D PDOPs are greatly reduced. Based on this, a basic idea of correcting satellite clock errors and ephem- eris errors apart is put forward, and moreover, a specific method of separation is proposed. Satellite clock errors are separated in a master station with time synchronization, and all the remaining pseu- do-range errors after the satellite clock errors have been deducted are used to work out ephemeris corrections of all GEO satellites. By a comparative analysis of user positioning accuracy before and after differential, the wide area differential method is verified to be quite valid for GEO constellation.

关键词： geostationary orbitsatellite dilution of precision satellite ephemeris errors satellite clock errors wide area differential method

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Astronomical function and date of the Taosi observatory

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Science china(Physics,Mechanics & Astronomy) 2009年第1期52卷 151-158页

作者： WU JiaBi1. CHEN MeiDong2 & LIU CiYuan3 1.National Astronomical Observatories, chinese academy of sciences, Beijing 1.001.,{1. 2 Institute for the History of Natural Science, chinese academy of sciences, Beijing 1.001.,{1. 3 National time service center, chinese academy of sciences, Xi’an 71.600,{1. 1. National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China 2. Institute for the History of Natural Science Chinese Academy of Sciences Beijing 100010 China 3. National time {1. center Chinese Academy of Sciences Xi’an 710600 China

The Taosi site in Xiangfen County,Shanxi Province,may be the capital of the King Yao. Archeologists recently discovered a large semi-circular stamped-earth platform, II FJT1.which has a clear and definite pounded-earth central core together with a curved wall perforated by twelve gaps. The platform is said to be an ancient observatory used to determine the seasons by watching the sunrise. Each feature of II FJT1.was precisely measured and the data are reproduced in this paper. An astronomical analysis of slots E2 and E1. was carried out using the azimuths of the slots' centerlines and the vertical angle of the mountain ridge opposite, above which the sun rises. The results show that at present the sun is close to the two slots but does not exactly enter them at summer and winter solstice sunrise. Using 1.C analysis archeologists dated the site to about 21.0 BC. Because of the secular change in the obliquity of the ecliptic,at that date on the summer solstice the half-risen sun would have appeared inside slot E1. just to the right of the centerline,and on the winter solstice the sun would have been exactly on the centerline of slot E2. This result provides compelling proof that II FJT1.is an ancient observatory.

关键词： astro-archeology astro-chronology Taosi culture ancient observatory time service

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A study on volunteer augmentation navigation technology

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Science china(Physics,Mechanics & Astronomy) 2011年第6期54卷 1029-1034页

作者： WU HaiTao 1.2,LU XiaoChun 1.2,ZOU DeCai 1.2 & HAN Tao 1.2 1.National time {1. center,chinese academy of sciences,Xi’an 71.600,china 2 Key Laboratory of Precision Navigation and Timing Technology,chinese academy of sciences,Xi’an 71.600,china 1. National time {1. center Chinese Academy of Sciences Xi’an 710600 China2. Key Laboratory of Precision Navigation and Timing Technology Chinese Academy of Sciences Xi’an 710600 China

Navigation augmentation technology is one of the most common methods to increase the continuity,reliability and integrity of the global satellite navigation *** concept of volunteer augmentation navigation (VNA) is proposed and the elements and topological structure of VNA are also analyzed in this *** study focuses on the neural network model that volunteers and ordinary users use modern communication information network to exchange self-organizing *** neural cell model of Volunteer Augmentation Navigation using shared information is *** interactive general relative positioning is *** basic theories and methods of volunteer augmentation navigation are formed on the basis of the above-mentioned *** study of realization mechanism of volunteer augmentation technology helps to form a relatively integral architecture of volunteer augmentation navigation.A user self-service satellite navigation augmentation which combines information exchange and navigation services may strengthen the continuity,reliability and integrity of the navigation *** volunteer augmentation navigation theory proposed in this paper improves the traditional satellite navigation application model and expands the connotation and denotation of satellite navigation augmentation methods.

关键词： volunteer augmentation navigation self-organizing information exchange interactive general relative positioning

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Analysis and application of automatic deformation monitoring data for buildings and structures of mining area

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中国有色金属学会会刊：英文版 2011年第S3期21卷 516-522页

作者： XIAO Jie1. 2, 3, ZHANG Jin4 1. Institute of Geodesy and Geophysics, chinese academy of sciences, Wuhan 430077,{1. 2. Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, chinese academy of sciences, Wuhan 430077,{1. 3. Graduate School of chinese academy of sciences, Beijing 1.0049,{1. 4. Department of Surveying and Mapping, Taiyuan University of Technology, Taiyuan 030024,{1. Taiyuan Univ Technol Dept Surveying & Mapping Taiyuan 030024 Peoples R China chinese Acad Sci Inst Geodesy & Geophys Key Lab Dynam Geodesy Wuhan 430077 Peoples R China chinese Acad Sci Grad Sch Beijing 100049 Peoples R China

The buildings and structures of mines were monitored automatically using modern surveying technology. Through the analysis of the monitoring data, the deformation characteristics were found out from three aspects containing points, lines and regions, which play an important role in understanding the stable state of buildings and structures. The stability and deformation of monitoring points were analysed, and time-series data of monitoring points were denoised with wavelet analysis and Kalman filtering, and exponent function and periodic function were used to get the ideal deformation trend model of monitoring points. Through calculating the monitoring data obtained, analyzing the deformation trend, and cognizing the deformation regularity, it can better {1. mine safety production and decision-making.

关键词： wavelet analysis Kalman filtering deformation monitoring data analysis mine

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Identifying heavy hitters in high-speed network monitoring

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Science china(Information {1.) 2010年第3期53卷 659-676页

作者： ZHANG Yu1. FANG BinXing1.2 & ZHANG YongZheng2 1.esearch center of Computer Network and Information Security Technology, Harbin Institute of Technology, Harbin 1.0001.{1. 2Research center of Information Security, Institute of Computing Technology, chinese academy of sciences, Beijing 1.01.0,{1. 1. Research center of Computer Network and Information Security Technology Harbin Institute of Technology Harbin 150001 China2. Research Center of Information Security Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China

Identifying heavy hitters in a network traffic stream is important for a variety of network applications ranging from traffic engineering to anomaly detection such as detection of denial-of-service attacks. Existing methods generally examine newly arriving items in the stream, perform a small number of operations using a small amount of memory, and still provide guarantees on the identifying accuracy. In high-speed network monitoring, the update speed per item is extremely critical. However, so far as we know, there are no identifying algorithms which can provide constant update {1. (O(1.) in a weighted data stream. In this paper, we present an algorithm named Weighted Lossy Counting (WLC) which is able to identify heavy hitters in a high-speed weighted data stream with constant update {1.. WLC employs a novel efficient partially ordered data structure which is able to provide a fast per-item update speed while keeping the memory cost relatively low. We compare WLC with state-of-the-art algorithms for finding heavy hitters in real traffic traces. The experimental results show that WLC performs well in accuracy (recall, precision and average relative error) as other algorithms; moreover it has a much higher update speed at the cost of relatively larger memory space used. A theoretical worst-case memory bound of WLC is also derived in this paper; however, experiments with long real traffic traces show that WLC requires much less space than the theoretical bound in practice.

关键词： network traffic monitoring heavy hitter weighted data streams

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Optical results of the black hole microquasar SS 433

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 153-156页

作者： LI Hui1.2 & YAN JingZhi1.3 1.Purple Mountain Observatory,chinese {1. of sciences,Nanjing 21.008,china 2 Graduate University of chinese academy of sciences,Beijing 1.0049,china 3 service d’Astrophysique,CEA Saclay and University Paris Diderot,91.91.Gif-sur-Yvette,France 1. Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Service d’Astrophysique CEA Saclay and University Paris Diderot 91191 Gif-sur-Yvette France

We present optical spectroscopic observations of SS 433 during different precessional and orbital *** 2004,2007 and 2008 data provide us a good chance to study the variability of the Hα line at different orbital phases for nearly the same disk *** data show that the Hα of SS 433 usually had a symmetric profile between orbital phases 0.25-0.75,while an asymmetric structure with a strong red peak was observed for other orbital *** suggest that the orbital variability of Hα emission is connected with accretion flow from the donor star to the accretion *** addition,we attribute the dramatic increase of Hα emission during our 2007 observational run,which had a time scale of one day,to the emergence of strong jets.

关键词： high-mass X-ray binary black hole spectroscopy outflow wind relativistic jet

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Precise time Measurement System Based on GPIB

Precise Time Measurement System Based on GPIB

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ICEMI'2005第七届国际电子测量与仪器学术会议

作者： Dong Shaowu1.2 Qi Yi1.1.ational time {1. center chinese academy of sciences 3 Shuyuan Dong lu lintong Xi’an 71.600 Shaanxi china 2Graduate School of the chinese academy of sciences Beijing 1.0039

In this paper, a precise time measurement system based on GPIB interface was introduced. Personal computer combined with GPIB card is acts as the controller in the precise time comparison system, its

关键词： time Measurement GPIB.

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GPS Differential Calibration at NTSC

GPS Differential Calibration at NTSC

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ICEMI'2005第七届国际电子测量与仪器学术会议

作者： Dong Shaowu1 2 Wang Zhengming1 (1National time service center chinese academy of sciences 3 Shuyuan Dong lu lintong Xi’an 71.600 Shaanxi china) (2the Graduate School of the chinese academy of sciences Beijing 100039 china)

During August 2002 to November 2002 and July 2004 to November 2004, BIPM (Bureau International des Poids et Mesures) has organized two times GPS round trip calibration in Asia and Pacific region, in o

关键词： GPS calibration measurement.

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