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Schrama, Ernst (author), Visser, P.N.A.M. (author)
In this paper we review the precision orbit determination (POD) performance of the CryoSat-2 mission where we used all tracking data between June-2010 and Jan-2023; with station and beacon coordinates provided in the ITRF2020 reference system, we use a mean gravity model, and we use spacecraft specific models for modeling drag and radiation...
journal article 2023
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Schrama, F.N.H. (author), Beunder, Elisabeth M. (author), Panda, Sourav K. (author), Visser, Hessel Jan (author), Moosavi-Khoonsari, Elmira (author), Sietsma, J. (author), Boom, R. (author), Yang, Y. (author)
In hot metal desulphurisation (HMD) the slag will hold the removed sulphur. However, the iron that is lost when the slag is skimmed off, accounts for the highest costs of the HMD process. These iron losses are lower when the slag has a lower viscosity, which can be achieved by changing the slag composition. A lower slag basicity decreases the...
journal article 2021
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Schrama, F.N.H. (author), Beunder, Elisabeth M. (author), Panda, Sourav K. (author), Visser, Hessel Jan (author), Moosavi-Khoonsari, Elmira (author), Hunt, Adam (author), Sietsma, J. (author), Boom, R. (author), Yang, Y. (author)
The optimal hot metal desulphurisation (HMD) slag is defined as a slag with a sufficient sulphur removal capacity and a low apparent viscosity (η<sub>slag</sub>) which leads to low iron losses. In part I of this study, the fundamentals behind the optimal slag were discussed. In this part these fundamentals are explored by a Monte Carlo...
journal article 2021
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Schrama, F.N.H. (author), Beunder, Elisabeth M. (author), Visser, H. (author), Boom, R. (author), Sietsma, J. (author), Yang, Y. (author)
During the magnesium-lime co-injection process for hot metal desulphurisation, graphite can precipitate as a result of carbon oversaturation. The formed graphite is known to form a layer between the slag and the hot metal. This potentially blocks the sulphides, that are formed during the desulphurisation process, to reach the slag phase thus...
conference paper 2019
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Schrama, F.N.H. (author), Beunder, Elisabeth M. (author), Visser, H. (author), Sietsma, J. (author), Boom, R. (author), Yang, Y. (author)
Carbon may precipitate during the hot metal desulfurization (HMD) process as a result of carbon oversaturation because of temperature decrease. The precipitated carbon flakes form a layer between hot metal and slag. It is postulated that this carbon layer hampers desulfurization with magnesium by preventing MgS particles from reaching the...
journal article 2019
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Bouman, J. (author), Fuchs, M. (author), Ivins, E. (author), Van der Wal, W. (author), Schrama, E.J.O. (author), Visser, P.N.A.M. (author), Horwath, M. (author)
The orbit and instrumental measurement of the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) satellite mission offer the highest ever resolution capabilities for mapping Earth's gravity field from space. However, past analysis predicted that GOCE would not detect changes in ice sheet mass. Here we demonstrate that GOCE gravity...
journal article 2014
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Bouman, J. (author), Fiorot, S. (author), Fuchs, M. (author), Gruber, T. (author), Schrama, E.J.O. (author), Tscherning, C.C. (author), Veicherts, M. (author), Visser, P.N.A.M. (author)
Two of the GOCE Level 2 products are the gravity gradients (GGs) in the Gradiometer Reference Frame (GRF) and the GGs in the Local North-Oriented Frame (LNOF). The GRF is an instrument frame and the GGs are derived from the L1b GGs. The L1b to L2 GG processing involves corrections for temporal gravity variations, outlier detection and data gap...
conference paper 2011
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Bouman, J. (author), Fiorot, S. (author), Fuchs, M. (author), Gruber, T. (author), Schrama, E.J.O. (author), Tscherning, C. (author), Veicherts, M. (author), Visser, P.N.A.M. (author)
GOCE is ESA’s gravity field mission and the first satellite ever that measures gravitational gradients in space, that is, the second spatial derivatives of the Earth’s gravitational potential. The goal is to determine the Earth’s mean gravitational field with unprecedented accuracy at spatial resolutions down to 100 km. GOCE carries a gravity...
journal article 2011
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Visser, P.N.A.M. (author), Schrama, E.J.O. (author), Sneeuw, N. (author), Weigelt, M. (author)
The so-called Colombo-Nyquist (Colombo, The global mapping of gravity with two satellites, 1984) rule in satellite geodesy has been revisited. This rule predicts that for a gravimetric satellite flying in a (near-)polar circular repeat orbit, the maximum resolvable geopotential spherical harmonic degree (lmax) is equal to half the number of...
conference paper 2009
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Bouman, J. (author), Rispens, S. (author), Gruber, T. (author), Koop, R. (author), Schrama, E. (author), Visser, P. (author), Tscherning, C.C. (author), Veicherts, M. (author)
One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in...
journal article 2008
document
Schrama, E.J.O. (author), Visser, P.N.A.M. (author)
journal article 2007
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