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Astronomical function and date of the Taosi observatory

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 100012, china 2 Institute for the History of Natural Science, chinese academy of sciences, Beijing 100010, china 3 national time service center, chinese academy of sciences, xi’an 710600, china national Astronomical Observatories Chinese Academy of Sciences Beijing China Institute for the History of Natural Science Chinese Academy of Sciences Beijing China national time service center Chinese Academy of Sciences Xi’an 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 E12 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 14C analysis archeologists dated the site to about 2100 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 E12 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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System time offset based RAIM in combined GPS/Beidou navigation system

System time offset based RAIM in combined GPS/Beidou navigat...

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第三届中国卫星导航学术年会

作者： XU Longxia1,2,3*1, LI xiaoHui1,2, XUE YanRong1,2,3, CAI ChengLin4& GUO MeiJun1,3 1national time service center, chinese academy of sciences, xi’an 710600, china 2Key Laboratory of Precision Navigation and Timing Technology, chinese academy of sciences, xi’an 710600, china 3Graduate University of chinese academy of sciences, Beijing 100039, china 4Guilin University of Electronic Technology, Guilin, 541004, china

Compatibility and interoperability of GNSS （Global Navigation Satellite System） are becoming the main trend of future navigation. However, each navigation system has a time scale. When users positioning with not only one system, the time offset between them must be considered. There are several ways to acquire system time offsets. By adding unknown variables in the combined position equation to solve this variable is the commonly used way. For positioning with multi-constellations, system time offsets are some kind of burden which must be taken into account. This paper takes full use of the obtained offsets and proposes a new fault detection method for RAIM （Receiver Autonomous Integrity Monitoring）. Simulations are made to estimate the ability of this new method. This new method takes the high stability of system time offsets of GPS/Beidou system and applies it to assistant fault detection. This method has no additional requirements for navigation system and is fit for applied in receivers. It can be expected this method will be one means of RAIM for Beidou navigation system when integrated with other GNSS in future.

关键词： Compatibility and Interoperability time Offset Receiver Autonomous Integrity Monitoring Fault Detection.

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

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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, 541004, china 2 national time service center, chinese academy of sciences, Lintong 710600, china 3 Key Laboratory of Precision Navigation and Timing Technology, national time service center, chinese academy of sciences, Lintong 710600, china Gulin University of Electronic Technology Gulin China chinese academy of sciences Key Laboratory of Precision Navigation and Timing Technology National Time Service Center Lintong China (GRID:grid.9227.e) (ISNI:***) chinese academy of sciences National Time Service Center Lintong China (GRID:grid.9227.e) (ISNI:***) chinese academy of sciences Key Laboratory of Precision Navigation and Timing Technology National Time Service Center Lintong China (GRID:grid.9227.e) (ISNI:***)

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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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 service center,chinese academy of sciences,xi’an 710600,china 2 Key Laboratory of Precision Navigation and Timing Technology,chinese academy of sciences,xi’an 710600,china chinese academy of sciences National Time Service Center Xi’an China (GRID:grid.9227.e) (ISNI:***) chinese academy of sciences Key Laboratory of Precision Navigation and Timing Technology Xi’an China (GRID:grid.9227.e) (ISNI:***)

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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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 service 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 national time service center Chinese Academy of Sciences Lintong China Hunan Institute of Humanities Science and Technology Loudi China Graduate University of chinese academy of sciences Beijing 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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Improving the accuracy of image-based forest fire recognition and spatial positioning

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Science china(Technological sciences) 2010年第S1期53卷 184-190页

作者： JIANG LiLi 1,QI QingWen 1,ZHANG An 1,GUO ChaoHui 2 & CHENG xi 1,3 1 Institute of Geographical sciences and Natural Resources Research,chinese academy of sciences,Beijing 100101,china 2 china center for Resources Satellite Data and Applications,Beijing 100094,china 3Graduate University of chinese academy of sciences,Beijing 100049,china Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing China china center for Resources Satellite Data and Applications Beijing China Graduate University of chinese academy of sciences Beijing China

Forest fires are frequent natural *** is necessary to explore advanced means to monitor,recognize and locate forest fires so as to establish a scientific system for the early detection,real-time positioning and quick fighting of forest *** paper mainly expounds methods and algorithms for improving accuracy and removing uncertainty in image-based forest fire recognition and spatial ***,we discuss a method of forest fire recognition in visible-light *** are four aspects to improve accuracy and remove uncertainty in fire recognition:(1)eliminating factors of interference such as road and sky with high brightness,red leaves,other colored objects and objects that are lit up at night,(2)excluding imaging for specific periods and azimuth angles for which interference phenomena repeatedly occur,(3)improving the thresholding method for determining the flame border in image processing by adjusting the threshold to the season,weather and region,and (4)integrating the visible-light image method with infrared image ***,we examine infrared-image-based methods and approaches of improving the accuracy of forest fire recognition by combining the spectrum threshold with an object feature value such as the normalized difference vegetation index and excluding factors of disturbance such as interference signals,extreme weather and high-temperature ***,a method of visible analysis to enhance the accuracy of forest fire positioning is examined and realized;the method includes decreasing the visual angle,selecting central points,selecting the largest spots,and judging the selection of fire spots according to the central *** studies are examined and the results are found to be satisfactory.

关键词： forest fire monitoring spatial positioning accuracy improvement

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守时工作进展

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天文学进展 2004年第2期22卷 104-114页

作者：王正明中国科学院国家授时中心西安710600

随着近5年时间传递技术(多通道GPS/GLONASS CV、TWSTFT、GPS P3 CV)和原子时算法的发展,国际原子时TAI和各国的守时工作有了较大的进展,中国科学院国家授时中心(NTSC)和国内其他时间实验室的工作也不例外。介绍国际权度局(BIPM)时间部有... 详细信息

随着近5年时间传递技术(多通道GPS/GLONASS CV、TWSTFT、GPS P3 CV)和原子时算法的发展,国际原子时TAI和各国的守时工作有了较大的进展,中国科学院国家授时中心(NTSC)和国内其他时间实验室的工作也不例外。介绍国际权度局(BIPM)时间部有关2000～2003年TAI的研究进展,以及NTSC和国际、国内某些时间实验室守时工作简况。另外,自2000年以来国际上对UTC之未来的争论很激烈,因此就2003年5月28～30日在意大利都灵市举行的“UTC的未来”研讨会的情况也作一些介绍,以便国内天体测量相关学术领域的同行们对这些发展有一个基本的了解。

关键词：天体测量学守时综述国际原子时协调世界时

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An extended numerical model of the first exothermic peak for three dimensional printed cement-based materials

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Frontiers of Structural and Civil Engineering 2024年第1期18卷 80-88页

作者： Wei JIANG Wenqian LI xi CHEN School of Materials Science and Engineering Tongji UniversityShanghai 200092China School of Civil Engineering Tongji UniversityShanghai 200092China

The first exothermic peak of cement-based material occurs a few minutes after mixing,and the properties of three dimensional(3D)printed concrete,such as setting time,are very sensitive to *** this background,based on the classical Park cement exothermic model of hydration,we propose and construct a numerical model of the first exothermic peak,taking into account the proportions of C_(3)S,C_(3)A and quicklime in *** calculated parameters are calibrated by means of relevant published exothermic test *** is found that this developed model offers a good simulation of the first exothermic peak of hydration for C_(3)S and C_(3)A proportions from 0 to 100% of cement clinker and reflects the effect of quicklime content at 8%-10%.The unique value of this research is provision of an important computational tool for applications that are sensitive to the first exothermic peak of hydration,such as 3D printing.

关键词： 3D printed cement-based materials cement hydration the first exothermic peak liquid quick-setting agent numerical model

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IGS产品在GPS时间比对中的应用

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天文学报 2004年第4期45卷 428-436页

作者：高玉平中国科学院国家授时中心西安710600

在利用GPS CV(GPS Common View)技术进行高精度时间比对时,电离层和卫星位置误差对观测到的卫星信号的影响是不容忽视的,需要对它进行精确的估计和改正.讨论IGS精密星历和CODE全球总电子含量图(TEC MAPs)在GPS时间传递中的应用.计算结... 详细信息

在利用GPS CV(GPS Common View)技术进行高精度时间比对时,电离层和卫星位置误差对观测到的卫星信号的影响是不容忽视的,需要对它进行精确的估计和改正.讨论IGS精密星历和CODE全球总电子含量图(TEC MAPs)在GPS时间传递中的应用.计算结果表明,采用IGS产品可有效提高单站定时和远距离时间传递的精度.

关键词： IGS GPS 时间比对总电子含量电离层改正观测卫星信号单站星历

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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, china 2. Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, chinese academy of sciences, Wuhan 430077, china 3. Graduate School of chinese academy of sciences, Beijing 100049, china 4. Department of Surveying and Mapping, Taiyuan University of Technology, Taiyuan 030024, china Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Key Laboratory of Dynamic Geodesy Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Graduate School of chinese academy of sciences Beijing 100049 China Department of Surveying and Mapping Taiyuan University of Technology Taiyuan 030024 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 service mine safety production and decision-making.

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

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