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Document Type |
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Article In Journal |
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Document Title |
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Fitting Gravimetric Local and Global Quasi-Geoids to GPS/Levelling Data: The Role of Geoid/Quasi-Geoid Variations توافق نماذج الجيويد وشبيه الجيويد المحلية والعالمية مع قياسات النظام العالمي لتحديد المواقع والميزانيات: دور التغيرات بين الجيويد وشبيه الجيويد |
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Subject |
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Civil Engineering |
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Document Language |
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English |
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Abstract |
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The Global Positioning System (GPS) has been extensively utilized in surveying and mapping applications worldwide and in Egypt, which results in a crucial need for precise geoid models. Traditionally, global and local gravimetric quasi-geoid models are determined and, then, fitted to GPS/leveling data. In the context of precise geoid determination, a quasi-geoid determination has to be converted to a geoid model prior to fitting process. Neglecting such a transforming process leads to the absorption of these effects in the fitting residuals that, hence, may produce misleading results and interpretations. The geoid/quasi-geoid separations in Egypt have been computed and found to range from –0.074 m to 0.367 m, with an average of 0.060 m. Additionally, when the quasi-geoid to geoid conversion is performed, it has been found that the undulation of the EIGEN-CG01C global quasi-geoid model when compared to true undulations of HARN stations, have been decreased, in the mean sense, from 0.52 m to 0.46 m. That means an average improvement of accuracy of about 11%. Based on the obtained results, it can be concluded that the conversion of the quasi-geoid to the geoid is quite significant and it should be a regular step in precise geoid determination in Egypt. |
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ISSN |
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1319-1047 |
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Journal Name |
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Engineering Sciences Journal |
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Volume |
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20 |
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Issue Number |
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1 |
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Publishing Year |
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1430 AH
2009 AD |
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Number Of Pages |
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12 |
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Article Type |
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Article |
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Added Date |
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Sunday, October 11, 2009 |
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Researchers
| جمعة محمد داود | Gomaa M. Dawod | Researcher | | |
| هدى فيصل محمد | Hoda F. Mohamed | Researcher | | |
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