The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
Jingnan Liu - One of the best experts on this subject based on the ideXlab platform.
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empirically derived model of solar radiation pressure for beidou geo satellites
Journal of Geodesy, 2019Co-Authors: Chen Wang, Jing Guo, Qile Zhao, Jingnan LiuAbstract:A key limitation in the precise orbit determination (POD) of BeiDou geostationary Earth orbit (GEO) satellites is the relatively static observation geometry, which results in strong correlations between orbital elements, solar radiation pressure (SRP) parameters, and ambiguities. Satellite laser ranging (SLR) residuals of BeiDou G01 satellite orbits display a clear dependence on the Sun elongation angle e, as well as a bias of approximately − 40 cm. These indicate the low performance of BeiDou GEO orbits. In this study, we confirmed that the perturbation caused by the communication antenna generates the e-angle-dependent variation and the bias of approximately − 14.9 cm in BeiDou G01 SLR residuals. Besides, the orbit-normal (ON) attitude mode used by BeiDou GEO satellites as well as an orbital inclination of nearly 0° results in strong linear correlations between the POD estimated parameters, i.e., satellite’s initial position on the Z-axis and the constant Y-bias along the cross-track direction. Hence, the solar pressure models, such as Extended Code Orbit Model (ECOM) in ON mode, with the Y-axis along the cross-track direction are deficient for SRP estimation of BeiDou GEO satellites. In this study, an empirical a priori SRP model was established for BeiDou GEO satellites to enhance the ECOM using an empirical fitting approach. This proposed model is expressed in DYB frame using eight parameters. With this model, precise BeiDou GEO orbits in 2016 were determined. SLR validation indicated that the systematic e-angle-dependent error was reduced and the large negative bias almost vanished. In general, better than 10-cm root-mean-square of SLR validation was achieved, and also an improvement of 4–5 times over the five-parameter ECOM model was obtained.
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solar radiation pressure models for beidou 3 i2 s satellite comparison and augmentation
Remote Sensing, 2018Co-Authors: Chen Wang, Jing Guo, Qile Zhao, Jingnan LiuAbstract:As one of the most essential modeling aspects for precise orbit determination, solar radiation pressure (SRP) is the largest non-gravitational force acting on a navigation satellite. This study focuses on SRP modeling of the BeiDou-3 experimental satellite I2-S (PRN C32), for which an obvious modeling deficiency that is related to SRP was formerly identified. The satellite laser ranging (SLR) validation demonstrated that the orbit of BeiDou-3 I2-S determined with empirical 5-parameter Extended Code (Center for Orbit Determination in Europe) Orbit Model (ECOM1) has the sun elongation angle (e angle) dependent systematic error, as well as a bias of approximately −16.9 cm. Similar performance has been identified for European Galileo and Japanese QZSS Michibiki satellite as well, and can be reduced with the Extended ECOM model (ECOM2), or by using the a priori SRP model to augment ECOM1. In this study, the performances of the widely used SRP models for GNSS (Global Navigation Satellite System) satellites, i.e., ECOM1, ECOM2, and adjustable box-wing model have been compared and analyzed for BeiDou-3 I2-S satellite. In addition, the a priori SRP models are derived based on analytical cuboid box model and empirically spectra analysis, respectively. Use of the a priori model combined with ECOM1 was finally demonstrated to reduce the e-angle-dependent systematic error, and thus improved the radial orbit accuracy by nearly 35 per cent when compared to the solution with standalone ECOM1, as revealed by the one way SLR residuals.
Jing Guo - One of the best experts on this subject based on the ideXlab platform.
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empirically derived model of solar radiation pressure for beidou geo satellites
Journal of Geodesy, 2019Co-Authors: Chen Wang, Jing Guo, Qile Zhao, Jingnan LiuAbstract:A key limitation in the precise orbit determination (POD) of BeiDou geostationary Earth orbit (GEO) satellites is the relatively static observation geometry, which results in strong correlations between orbital elements, solar radiation pressure (SRP) parameters, and ambiguities. Satellite laser ranging (SLR) residuals of BeiDou G01 satellite orbits display a clear dependence on the Sun elongation angle e, as well as a bias of approximately − 40 cm. These indicate the low performance of BeiDou GEO orbits. In this study, we confirmed that the perturbation caused by the communication antenna generates the e-angle-dependent variation and the bias of approximately − 14.9 cm in BeiDou G01 SLR residuals. Besides, the orbit-normal (ON) attitude mode used by BeiDou GEO satellites as well as an orbital inclination of nearly 0° results in strong linear correlations between the POD estimated parameters, i.e., satellite’s initial position on the Z-axis and the constant Y-bias along the cross-track direction. Hence, the solar pressure models, such as Extended Code Orbit Model (ECOM) in ON mode, with the Y-axis along the cross-track direction are deficient for SRP estimation of BeiDou GEO satellites. In this study, an empirical a priori SRP model was established for BeiDou GEO satellites to enhance the ECOM using an empirical fitting approach. This proposed model is expressed in DYB frame using eight parameters. With this model, precise BeiDou GEO orbits in 2016 were determined. SLR validation indicated that the systematic e-angle-dependent error was reduced and the large negative bias almost vanished. In general, better than 10-cm root-mean-square of SLR validation was achieved, and also an improvement of 4–5 times over the five-parameter ECOM model was obtained.
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solar radiation pressure models for beidou 3 i2 s satellite comparison and augmentation
Remote Sensing, 2018Co-Authors: Chen Wang, Jing Guo, Qile Zhao, Jingnan LiuAbstract:As one of the most essential modeling aspects for precise orbit determination, solar radiation pressure (SRP) is the largest non-gravitational force acting on a navigation satellite. This study focuses on SRP modeling of the BeiDou-3 experimental satellite I2-S (PRN C32), for which an obvious modeling deficiency that is related to SRP was formerly identified. The satellite laser ranging (SLR) validation demonstrated that the orbit of BeiDou-3 I2-S determined with empirical 5-parameter Extended Code (Center for Orbit Determination in Europe) Orbit Model (ECOM1) has the sun elongation angle (e angle) dependent systematic error, as well as a bias of approximately −16.9 cm. Similar performance has been identified for European Galileo and Japanese QZSS Michibiki satellite as well, and can be reduced with the Extended ECOM model (ECOM2), or by using the a priori SRP model to augment ECOM1. In this study, the performances of the widely used SRP models for GNSS (Global Navigation Satellite System) satellites, i.e., ECOM1, ECOM2, and adjustable box-wing model have been compared and analyzed for BeiDou-3 I2-S satellite. In addition, the a priori SRP models are derived based on analytical cuboid box model and empirically spectra analysis, respectively. Use of the a priori model combined with ECOM1 was finally demonstrated to reduce the e-angle-dependent systematic error, and thus improved the radial orbit accuracy by nearly 35 per cent when compared to the solution with standalone ECOM1, as revealed by the one way SLR residuals.
Chen Wang - One of the best experts on this subject based on the ideXlab platform.
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empirically derived model of solar radiation pressure for beidou geo satellites
Journal of Geodesy, 2019Co-Authors: Chen Wang, Jing Guo, Qile Zhao, Jingnan LiuAbstract:A key limitation in the precise orbit determination (POD) of BeiDou geostationary Earth orbit (GEO) satellites is the relatively static observation geometry, which results in strong correlations between orbital elements, solar radiation pressure (SRP) parameters, and ambiguities. Satellite laser ranging (SLR) residuals of BeiDou G01 satellite orbits display a clear dependence on the Sun elongation angle e, as well as a bias of approximately − 40 cm. These indicate the low performance of BeiDou GEO orbits. In this study, we confirmed that the perturbation caused by the communication antenna generates the e-angle-dependent variation and the bias of approximately − 14.9 cm in BeiDou G01 SLR residuals. Besides, the orbit-normal (ON) attitude mode used by BeiDou GEO satellites as well as an orbital inclination of nearly 0° results in strong linear correlations between the POD estimated parameters, i.e., satellite’s initial position on the Z-axis and the constant Y-bias along the cross-track direction. Hence, the solar pressure models, such as Extended Code Orbit Model (ECOM) in ON mode, with the Y-axis along the cross-track direction are deficient for SRP estimation of BeiDou GEO satellites. In this study, an empirical a priori SRP model was established for BeiDou GEO satellites to enhance the ECOM using an empirical fitting approach. This proposed model is expressed in DYB frame using eight parameters. With this model, precise BeiDou GEO orbits in 2016 were determined. SLR validation indicated that the systematic e-angle-dependent error was reduced and the large negative bias almost vanished. In general, better than 10-cm root-mean-square of SLR validation was achieved, and also an improvement of 4–5 times over the five-parameter ECOM model was obtained.
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solar radiation pressure models for beidou 3 i2 s satellite comparison and augmentation
Remote Sensing, 2018Co-Authors: Chen Wang, Jing Guo, Qile Zhao, Jingnan LiuAbstract:As one of the most essential modeling aspects for precise orbit determination, solar radiation pressure (SRP) is the largest non-gravitational force acting on a navigation satellite. This study focuses on SRP modeling of the BeiDou-3 experimental satellite I2-S (PRN C32), for which an obvious modeling deficiency that is related to SRP was formerly identified. The satellite laser ranging (SLR) validation demonstrated that the orbit of BeiDou-3 I2-S determined with empirical 5-parameter Extended Code (Center for Orbit Determination in Europe) Orbit Model (ECOM1) has the sun elongation angle (e angle) dependent systematic error, as well as a bias of approximately −16.9 cm. Similar performance has been identified for European Galileo and Japanese QZSS Michibiki satellite as well, and can be reduced with the Extended ECOM model (ECOM2), or by using the a priori SRP model to augment ECOM1. In this study, the performances of the widely used SRP models for GNSS (Global Navigation Satellite System) satellites, i.e., ECOM1, ECOM2, and adjustable box-wing model have been compared and analyzed for BeiDou-3 I2-S satellite. In addition, the a priori SRP models are derived based on analytical cuboid box model and empirically spectra analysis, respectively. Use of the a priori model combined with ECOM1 was finally demonstrated to reduce the e-angle-dependent systematic error, and thus improved the radial orbit accuracy by nearly 35 per cent when compared to the solution with standalone ECOM1, as revealed by the one way SLR residuals.
Marcel J. M. Groenen - One of the best experts on this subject based on the ideXlab platform.
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Gastrointestinal Endoscopic Terminology Coding (GET-C): A WHO-Approved Extension of the ICD-10
Digestive Diseases and Sciences, 2007Co-Authors: Marcel J. M. Groenen, Willem Hirs, Henk Becker, Ernst J. Kuipers, Gerard P. Berge Henegouwen, Paul Fockens, Rob J. Th. OuwendijkAbstract:Technological developments have greatly promoted interest in the use of computer systems for recording findings and images at endoscopy and creating databases. The aim of this study was to develop a comprehensive WHO-approved Code system for gastrointestinal endoscopic terminology. The International Classification of Diseases, 10th edition (ICD-10), and the ICD-10 clinical modification (ICD-10-CM) were expanded to allow description of every possible gastrointestinal endoscopic term under conditions defined by the WHO. Classifications of specific gastrointestinal disorders and endoscopic locations were added. A new chapter was developed for frequently used terminology that could not be classified in the existing ICD-10, such as descriptions of therapeutic procedures. The new Extended Code system was named Gastrointestinal Endoscopic Terminology Coding (GET-C). The GET-C is a complete ICD-10-related Code system that can be used within every endoscopic database program for all specific endoscopic terms. The GET-C is available for free at http://www.trans-it.org/.
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3431 Gastrointestinal endoscopic terminology coding; GET-C. An Extended coding system based on the internal classification of diseases-10th edition.
Gastrointestinal Endoscopy, 2000Co-Authors: Marcel J. M. Groenen, Rob J. Ouwendijk, Gerard P. Van Berge HenegouwenAbstract:Endoscopic report systems are becoming more and more available in the current endoscopic practice. The way reports are composed and data is stored differ considerable between the systems. They all use different kinds of databases and it is only possible to evaluate the endoscopic data of their own system. One problem is that there is no specific Code system for endoscopic terminology and findings that is widely used. To be able to compare different ways of report writing we developed a comprehensive Code-system suitable to Code every used term during gastrointestinal endoscopy. This new Extended Code system was based on a Code-system, already in use throughout the world. The International Classification of Diseases 10thedition (ICD-10) is a comprehensive and widely used Codesystem, published by the World Health Organization (WHO) and translated into many different languages. The ICD-10 was originally composed for mortality statistics. However on conditions defined by the WHO this ICD- 10 can be Extended for local purposes. Terms that are used during gastrointestinal endoscopy were based on Minimal Standard Terminology (MST). However MST only includes terms that are commonly used. So this list was expanded to be able to describe every possible gastrointestinal endoscopic term. By extending the ICD-10 a complete coding system for endoscopic terminology was created on conditions of the WHO. It is possible to Code every indication. In this way, it is also possible to Code severity and classification of certain endoscopic findings into generally used grading scores. Abnormalities that can only be endoscopically diagnosed and precise locations were added. The medication given during the examination, the proceeding of the examination, any therapeutic interventions but also complications can be given a specific Code. A project was started to evaluate endoscopic examinations in the Netherlands. In this TRANS.IT project, different ways of report writing are used in Endobase III® and a central database is build by collecting the GET-C Codes that are linked to these reports. Yet, this new Code-system can be implemented in every endoscopic database system. Conclusions Gastrointestinal Endoscopic Terminology Coding (GET-C) is a complete Code system that can be used in every endoscopic database program. Each endoscopic term has its own specific Code. Using this Code-system it is possible to compare different endoscopic databases even internationally.
Qile Zhao - One of the best experts on this subject based on the ideXlab platform.
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empirically derived model of solar radiation pressure for beidou geo satellites
Journal of Geodesy, 2019Co-Authors: Chen Wang, Jing Guo, Qile Zhao, Jingnan LiuAbstract:A key limitation in the precise orbit determination (POD) of BeiDou geostationary Earth orbit (GEO) satellites is the relatively static observation geometry, which results in strong correlations between orbital elements, solar radiation pressure (SRP) parameters, and ambiguities. Satellite laser ranging (SLR) residuals of BeiDou G01 satellite orbits display a clear dependence on the Sun elongation angle e, as well as a bias of approximately − 40 cm. These indicate the low performance of BeiDou GEO orbits. In this study, we confirmed that the perturbation caused by the communication antenna generates the e-angle-dependent variation and the bias of approximately − 14.9 cm in BeiDou G01 SLR residuals. Besides, the orbit-normal (ON) attitude mode used by BeiDou GEO satellites as well as an orbital inclination of nearly 0° results in strong linear correlations between the POD estimated parameters, i.e., satellite’s initial position on the Z-axis and the constant Y-bias along the cross-track direction. Hence, the solar pressure models, such as Extended Code Orbit Model (ECOM) in ON mode, with the Y-axis along the cross-track direction are deficient for SRP estimation of BeiDou GEO satellites. In this study, an empirical a priori SRP model was established for BeiDou GEO satellites to enhance the ECOM using an empirical fitting approach. This proposed model is expressed in DYB frame using eight parameters. With this model, precise BeiDou GEO orbits in 2016 were determined. SLR validation indicated that the systematic e-angle-dependent error was reduced and the large negative bias almost vanished. In general, better than 10-cm root-mean-square of SLR validation was achieved, and also an improvement of 4–5 times over the five-parameter ECOM model was obtained.
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solar radiation pressure models for beidou 3 i2 s satellite comparison and augmentation
Remote Sensing, 2018Co-Authors: Chen Wang, Jing Guo, Qile Zhao, Jingnan LiuAbstract:As one of the most essential modeling aspects for precise orbit determination, solar radiation pressure (SRP) is the largest non-gravitational force acting on a navigation satellite. This study focuses on SRP modeling of the BeiDou-3 experimental satellite I2-S (PRN C32), for which an obvious modeling deficiency that is related to SRP was formerly identified. The satellite laser ranging (SLR) validation demonstrated that the orbit of BeiDou-3 I2-S determined with empirical 5-parameter Extended Code (Center for Orbit Determination in Europe) Orbit Model (ECOM1) has the sun elongation angle (e angle) dependent systematic error, as well as a bias of approximately −16.9 cm. Similar performance has been identified for European Galileo and Japanese QZSS Michibiki satellite as well, and can be reduced with the Extended ECOM model (ECOM2), or by using the a priori SRP model to augment ECOM1. In this study, the performances of the widely used SRP models for GNSS (Global Navigation Satellite System) satellites, i.e., ECOM1, ECOM2, and adjustable box-wing model have been compared and analyzed for BeiDou-3 I2-S satellite. In addition, the a priori SRP models are derived based on analytical cuboid box model and empirically spectra analysis, respectively. Use of the a priori model combined with ECOM1 was finally demonstrated to reduce the e-angle-dependent systematic error, and thus improved the radial orbit accuracy by nearly 35 per cent when compared to the solution with standalone ECOM1, as revealed by the one way SLR residuals.
