Rigorous transformation of variance–covariance matrices of GPS-derived coordinates and velocities     

Tomás Soler  John Marshall 《GPS Solutions》2002,6(1-2):76-90

With the advances in the field of GPS positioning and the global densification of permanent GPS tracking stations, it is now possible to determine at the highest level of accuracy the transformation parameters connecting various international terrestrial reference frame (ITRF) realizations. As a by-product of these refinements, not only the seven usual parameters of the similarity transformations between frames are available, but also their rates, all given at some epoch t _k . This paper introduces rigorous matrix equations to estimate variance–covariance matrices for transformed coordinates at any epoch t based on a stochastic model that takes into consideration all a priori information of the parameters involved at epoch t _k , and the coordinates and velocities at the reference frame initial epoch t ₀. The results of this investigation suggest that in order to attain maximum accuracy, the agencies determining the 14-parameter transformations between reference frames should also publish their full variance–covariance matrix. Electronic Publication  相似文献   

Phase relations governing the derivation of alkaline basaltic magmas from primary magmas at high pressures     

Sven Maaløe  Tom Svane Petersen 《Lithos》1976,9(3):243-252

A comparison between the variation trend of alkaline basaltic magmas within the CaO-MgO-Al₂O₃-SiO₂ system and experimentally estimated phase relations for this system at high pressures, suggests an olivine reaction relationship, which may explain the transition from primary magmas in equilibrium with olivine to alkaline basaltic magmas in which olivine does not form at high pressures. This reaction relationship is considered to be due to a transition from positive to negative crystallization with respect to olivine along the four phase curve where olivine, diopside, pyrope garnet and liquid are initially in equilibrium. The bimineralic, eclogitic character of alkaline basaltic compositions at high pressures is interpreted as being due to the presence of a thermal minimum on the three phase surface, where dioside and pyrope garnet are in equilibrium with liquid.  相似文献   

Sphalerite composition in relation to the stress distribution of a boudinage     

Sandor Berglund  Tom K. Ekström 《Lithos》1974,7(1):1-6

The content of FeS in sphalerites from different parts of a boudinage is compared with the theoretical stress pattern. The calculated differences in stress correspond to less than one mole percent FeS and are often masked by the small variations in the fugacity of sulfur.  相似文献   

Tracking and orbit determination performance of the GRAS instrument on MetOp-A   总被引：8，自引：3，他引：5  

Oliver Montenbruck  Yago Andres  Heike Bock  Tom van Helleputte  Jose van den Ijssel  Marc Loiselet  Christian Marquardt  Pierluigi Silvestrin  Pieter Visser  Yoke Yoon 《GPS Solutions》2008,12(4):289-299

The global navigation satellite system receiver for atmospheric sounding (GRAS) on MetOp-A is the first European GPS receiver providing dual-frequency navigation and occultation measurements from a spaceborne platform on a routine basis. The receiver is based on ESA’s AGGA-2 correlator chip, which implements a high-quality tracking scheme for semi-codeless P(Y) code tracking on the L1 and L2 frequency. Data collected with the zenith antenna on MetOp-A have been used to perform an in-flight characterization of the GRAS instrument with focus on the tracking and navigation performance. Besides an assessment of the receiver noise and systematic measurement errors, the study addresses the precise orbit determination accuracy achievable with the GRAS receiver. A consistency on the 5 cm level is demonstrated for reduced dynamics orbit solutions computed independently by four different agencies and software packages. With purely kinematic solutions, 10 cm accuracy is obtained. As a part of the analysis, an empirical antenna offset correction and preliminary phase center correction map are derived, which notably reduce the carrier phase residuals and improve the consistency of kinematic orbit determination results.

Oliver MontenbruckEmail:

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A method for predicting swelling pressure of compacted bentonites   总被引：1，自引：0，他引：1  

Setianto Samingan Agus  Tom Schanz 《Acta Geotechnica》2008,3(2):125-137

An approach for predicting swelling pressure of bentonites based on thermodynamic relationships between swelling pressure and suction is presented in this paper. The proposed method requires sorption isotherm data of the bentonites. A series of swelling pressure tests were performed on compacted specimens of bentonite-sand mixtures with different bentonite contents, water contents, and dry densities. The sorption isotherm of the pure bentonite was measured using a chilled-mirror hygrometer. It is found that the method works well for the bentonite-sand mixtures tested. Several published data on bentonites that have been proposed to be used as buffer and sealing material for nuclear waste repository were collected and used to verify the method. The proposed method is found to be also applicable for other bentonites of different types and therefore, can be used to predict swelling pressure of bentonites.  相似文献   

Droughts,Floods and Cyclones. El Ninos that Shaped Our Colonial Past – By Don Garden     

Tom Brooking 《New Zealand geographer》2010,66(2):170-171

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Geomorphological signature and flow dynamics of The Minch palaeo‐ice stream,northwest Scotland     

Tom Bradwell  Martyn Stoker  Rob Larter 《第四纪科学杂志》2007,22(6):609-617

Large‐scale streamlined glacial landforms are identified in 11 areas of northwest Scotland, from the Isle of Skye in the south to the Butt of Lewis in the north. These ice‐directional features occur in bedrock and superficial deposits, generally below 350 m above sea level, and where best developed have elongation ratios of >20:1. Sidescan sonar and multibeam echo‐sounding data from The Minch show elongate streamlined ridges and grooves on the seabed, with elongation ratios of up to 70:1. These bedforms are interpreted as mega‐scale glacial lineations. All the features identified formed beneath The Minch palaeo‐ice stream which was ca. 200 km long, up to 50 km wide and drained ca. 15 000 km² of the northwest sector of the last British‐Irish Ice Sheet (Late Devensian Glaciation). Nine ice‐stream tributaries and palaeo‐onset zones are also identified, on the basis of geomorphological evidence. The spatial distribution and pattern of streamlined bedforms around The Minch has enabled the catchment, flow paths and basal shear stresses of the palaeo‐ice stream and its tributaries to be tentatively reconstructed. © British Geological Survey/Natural Environment Research Council copyright 2007. Reproduced with the permission of BGS/NERC. Published by John Wiley & Sons, Ltd.  相似文献   

Taking the pulse of hydrology education     

Thorsten Wagener  Markus Weiler  Brian McGlynn  Mike Gooseff  Tom Meixner  Lucy Marshall  Kevin McGuire  Mike McHale 《水文研究》2007,21(13):1789-1792

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Observation of wind-waves from a moored buoy in the Southern Ocean   总被引：1，自引：1，他引：0  

Henrique Rapizo  Alexander V. Babanin  Eric Schulz  Mark A. Hemer  Tom H. Durrant 《Ocean Dynamics》2015,65(9-10):1275-1288

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Complexity Phenomena and ROMA of the Earth’s Magnetospheric Cusp,Hydrodynamic Turbulence,and the Cosmic Web     

Tom Chang  Cheng-chin Wu  Marius Echim  Hervé Lamy  Mark Vogelsberger  Lars Hernquist  Debora Sijacki 《Pure and Applied Geophysics》2015,172(7):2025-2043

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