Results 51 to 60 of about 1,485 (143)

A Statistical Study on Force-Freeness of Solar Magnetic Fields in the Photosphere

, 2012
It is an indisputable fact that solar magnetic fields are force-free in the corona, where force free fields means that current and magnetic fields are parallel and there is no Lorentz force in the fields.
Ai, Ai, Aly, Amari, Bao, Chandrasekhar, Demoulin, Gary, H. Q. Zhang, He, J. T. Su, Krall, Liu, Liu, Low, Metcalf, Mikic, Molodensky, Priest, S. Liu, Sakurai, Stenflo, Su, Wang, Wang, Wang, Wang, Wiegelmann, Wiegelmann, X. J. Mao, X. Yang, Y. Gao, Y. Y. Deng, Yan, Zhang   +34 more
core   +1 more source

A New Application of the Lunar Laser Retroreflectors: Searching for the "Local" Hubble Expansion [PDF]

, 2003
Precise measurements of the Earth-Moon distance by the lunar laser ranging (LLR), which begun in the early 1970's, contributed significantly to geodesy, geophysics, and lunar planetology, as well as enabled astrophysicists to perform several fine tests ...
Bec-Borsenberger, Bender, Chernin, Dickey, Domínguez, Dumin, Dumin, Ekholm, Horellou, Kaula, Misner, Nordtvedt, Pertsev, Samain, Sidorenkov, Yu.V. Dumin   +15 more
core   +3 more sources

Challenges and Harmonization of Local Datum Transformations within the Coordinate Reference Systems of North Macedonia [PDF]

Micro, Macro & Mezzo Geoinformation
Accurate, reliable, and interoperable coordinate reference systems (CRS) form the basis of all modern geospatial, surveying, engineering, and cadastral activities.
Zoran Cvetkovski, Nikola Ribaroski
doaj   +1 more source

First Stereoscopic Coronal Loop Reconstructions from Stereo Secchi Images

, 2007
We present the first reconstruction of the three-dimensional shape of magnetic loops in an active region from two different vantage points based on simultaneously recorded images.
Feng, L., Howard, R. A., Inhester, B., Podlipnik, B., Solanki, S. K., Wiegelmann, T., Wuelser, J. -P.   +6 more
core   +1 more source

Modeling Magnetic Field Structure of a Solar Active Region Corona using Nonlinear Force-Free Fields in Spherical Geometry [PDF]

, 2012
We test a nonlinear force-free field (NLFFF) optimization code in spherical geometry using an analytical solution from Low and Lou. Several tests are run, ranging from idealized cases where exact vector field data are provided on all boundaries, to cases
DeRosa, M. L., Ding, M. D., Guo, Y., Liu, Y., Sun, X. D., Wiegelmann, T.   +5 more
core   +1 more source

GEOID-QUASIGEOID CORRECTION IN FORMULATION OF THE FUNDAMENTAL FORMULA OF PHYSICAL GEODESY

Revista Brasileira de Cartografia, 2006
To formulate the fundamental formula of physical geodesy at the physical surface of the Earth, the gravity anomalies are used instead of the gravity disturbances, because the geodetic heights above the geocentric reference ellipsoid are not usually ...
Robert Tenzer, Petr Vaníček
doaj  

Determination of the Quasi-Geoid of Xinjiang and Tibet Areas and the Normal Height of Mt. Everest Based on EGM2008

Terrestrial, Atmospheric and Oceanic Sciences, 2011
The normal height H* is the height above the quasi-geoid, which coincides with the geoid in the ocean but slightly deviates from the geoid in terrestrial areas. In Mainland China, the height datum system is based on the quasi-geoid.
WenBin Shen, Jin Li, Bin Tian, Jiancheng Han   +3 more
doaj   +1 more source

Transformaciones de Datum.

Uniciencia, 2004
Con el uso generalizado de las técnicas satelitales aplicadas en topografía y geodesia, se ha generado la necesidad de transformar entre marcos coordenados de referencia globales y locales.
Manuel Ramírez, Juan G. Serpas
doaj  

A methodology for transformation between geodetic datums used in Syria

Journal of King Saud University: Engineering Sciences
The Global Navigation Satellite System (GNSS) provides geodetic coordinates referenced to the world ellipsoid WGS84, whereas positions are computed on the local ellipsoid adopted for geodetic computation in various countries.
Al-Kasem Shaza, Ramadan A. Al-Razzak, Jibrini Hasan   +2 more
doaj   +1 more source

On the topographic bias by harmonic continuation of the geopotential for a spherical sea-level approximation

Journal of Geodetic Science
Topography is a problem in geoid determination by the Stokes formula, a high degree Earth Gravitational Model (EGM), or for a combination thereof. Herein, we consider this problem in analytical/harmonic downward continuation of the external potential at ...
Sjöberg Lars E.
doaj   +1 more source