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Moek, G. (author), Traas, C.R. (author)In practical applications of Kalman filtering theory often inconsistencies between real estimation errors and computed error variances occur due to modelling errors. An adaptive filtering technique has been developed at NLR to deal with this filter divergence problem. Special attention is paid to divergence detection. When divergence is detected...report 1981
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Traas, C.R. (author)The present issue is the second and final part of a report describing the results of a study about digital filtering. The first part is available as the report NLR TR 760U8 U. The report considers a number of digital filtering methods and gives examples of their application. The methods include batch processing methods and recursive methods....report 1979
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Traas, C.R. (author), Moek, G. (author)The attitude measurement data of the ESA geosynchronous spacecraft METEOSAT have been analyzed using an adaptive recursive filtering technique developed at NLR. The mathematical models of spacecraft dynamics and sensors have been kept very simple. Modelling errors are such that, without adaptive feed-back, strong divergence of the filtering...report 1978
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van Woerkom, P.T.L.M. (author), Traas, C.R. (author)The ESA starmapper is an optical-electronic instrument with an array of photo-sensitive slits, to "be strapped down to spinning spacecraft. Recorded times of passage of known stars over these slits, together with mathematical models for spacecraft dynamics and starmapper instrument, provide the basis for recursive estimation of the spacecraft...report 1978
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- Traas, C.R. (author) report 1977
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Traas, C.R. (author)Paper presented at the 27th Congress of the I.A.F., October 10-I6, 1976, Anaheim, USA.report 1976
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Traas, C.R. (author)The report reviews a number of digital filtering methods and gives examples of their application. The methods include batch processing methods and rec\irsive methods, not only in the classical formulations but also in square-root formulations. The latter formulations have the purpose to prevent certain numerical inconveniences. Much attention is...report 1976
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Traas, C.R. (author)The simulation of a class of three-dimensional, stationary, supersonic gas flows by construction of an approximate solution to the governing system of partial differential equations, is analysed. The investigated method is a hybrid one: it involves finite difference calculations on a regular, orthogonal grid, and characteristics calculations,...report 1975
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- Traas, C.R. (author) report 1973
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Lindhout, J.P.F. (author), Traas, C.R. (author)In this report a program in ALGOL (CDC-3300, MBOS (3,2) operating system) is described for the computation of the supersonic flow of a thermally and calorically perfect gas around axisymnetric bodies. Computational details are given and some numerical results are presented. Emphasis is placed on the organization of the program. For a specific...report 1973
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- Traas, C.R. (author), van Woerkom, P.T.L.M. (author) report 1972
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Traas, C.R. (author)An investigation has been performed to obtain a reliable and economical method for the numerical integration of second order ordinary differential equations of considerable complexity over a long interval. A Nordsieck process of 10th order has been selected for this purpose, A derivation of the process is given in this report. Stability and...report 1969
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Traas, C.R. (author)An accurate inverse method for the numerical calculation of the supersonic flow around an axisymmetric blunt body is presented. By a suitable transformation the field under connideration is mapped on a rectangular strip. Integration of the equations of motion in the transformed domain is performed by simultaneous application of a third order...report 1968
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Traas, C.R. (author)An accurate inverse method for the numerical computation of the supersonic flow around a blunt body, on the presupposition of ideal gas properties, is presented. By a suitable transformation the field under consideration is mapped on a rectangular strip. Integration of the equations of motion in the transformed domain is performed by...report 1967