document

Flow estimation for the Persian Gulf using a Kelvin wave expansion

Badri, M.A. (author), Wilders, P. (author), Azimian, A.R. (author)

Hydrodynamic simulations of tidal currents in the Persian Gulf are presented. Water surface level and velocity have been determined by a Kelvin wave expansion as a new hydrodynamic calibration tool for estimating the dynamical field and flow patterns. In the procedure, leading to the Kelvin wave expansion, data of tidal constituents from co...

report 2010

document

Goal-Oriented A-Posteriori Error Estimation and Adaptivity for Fluid-Structure Interaction

Fick, P.W. (author), Van der Zee, K.G. (author), Van Brummelen, E.H. (author)

Numerical simulation of fluid-structure interaction generally requires vast computational resources. Paradoxically, the computational work is dominated by the complexity of the subsystem that is of least practical interest, viz. the fluid. The resolution of each of the many small-scale features in the fluid is prohibitively expensive. However,...

report 2008

document

Attitude estimation for low-cost spacecraft equipped with GPS

Chu, Q.P. (author), Zwartbol, T. (author), van Woerkom, P.T.L.M. (author)

The objective of the present paper is to give an overview of spacecraft attitude determination with GPS. GPS receivers with single or multiple antennas nowadays are low-cost sensors that constitute a valuable complement to existing sensor suites. GPS has been widely used for positioning and vehicle navigation. However, using GPS as an attitude...

report 1995

document

Werk in Uitvoering: Een handreiking met suggesties en ideeen

Anonymus, A. (author)

Werkmap bij de PRI systematiek (Project Ramingen Infrastructuur) van Rijkswaterstaat. Het beslaat de onderdelen (1) Goed omgaan met ramen,(2) Rekenen aan projecten en (3) Begrippenkader. Zo behelzen de bijdragen in hoofdstuk 1 vooral onderwerpen die met de organisatie hebben te maken. Deze zijn daarom vooral interessant voor projectleiders en...

report 1995

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Some aerospace applications of estimation theory

Moek, G. (author)

In this report, the application of estimation theory to three problems from aerospace research is described. The applications considered deal with spacecraft attitude estimation, software reliability modelling and estimation, and with a satellite-based navigation algorithm. Maximum likelihood estimation is used in the software reliability case...

report 1991

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Bayesian estimation for decision-directed stochastic control

Blom, H.A.P. (author)

Stochastic processes with a decision-directed control are considered as controlled Markov processes, the state space of which is hybrid; i.e. a product of a discrete set and a Euclidean space. This approach yields a mathematical model for many problems of decision-directed stochastic control. In general, the observations made from the "past" and...

report 1990

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Estimating the probability of vertical overlap from the paired aircraft data obtained in the european vertical data collection using the program DGLDiF

Moek, G. (author)

The problem of estimating the probability of vertical overlap in possible future airway systems with a vertical separation standard of 1000 ft above Flight Level 290 is addressed. It forms part of an overall safety assessment of such potential systems. The problem is solved by developing a mathematical probability model of the vertical distance...

report 1988

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Approximate confidence regions for the parameters of three software reliability models

Moek, G. (author)

Expressions are derived from which confidence regions for the parameters of three specific software reliability models can be computed. These expressions are based on the asymptotic probability distribution of the maximum likelihood estimator. Some numerical results of point estimates as well as confidence regions are given, based on simulated...

report 1987

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A positioning system based on NAVSAT

de Reus, N.M. (author), Moek, G. (author), Olsder, G.J. (author)

A worldwide navigation system called NAVSAT is discussed. This positioning system is based on satellites which broadcast information which can be used by receivers of this Information to estimate their position. The motion of the users is modelled by splines. The estimation procedure is based on the extended Kalman filter approach.

report 1987

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Study of NAVSAT control segment characteristics: part III: executive summary

Joosten, L.J.M. (author), Wakker, K.F. (author)

On the proposed satellite-based navigation system NAVSAT, a study has been performed concerning the characteristics of the control segment. Starting from the outcome of earlier preliminary studies of ESA, this study shows that the concept is feasible.

report 1985

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In-flight attitude estimations and control experiments with Iras based on modern control theory

Terpstra, A.P. (author), Zwartbol, T. (author), Slippens, C.P.R.C. (author)

One of the research activities of the Space Division of the National Aerospace Laboratory NLR is the application of modern estimation and control theory to spacecraft attitude control problems. Algorithms for spacecraft state estimation and attitude control, as well as for inertial-optical attitude determination have been developed previously...

report 1984

document

Reliability of nondestructive inspection

Heida, J.H. (author)

This report describes the concept of reliability of nondestructive inspection (NDI) and reviews the different aspects involved. First, the probability of detection (POD) of flaws in flawed specimens is discussed. To provide a measure of confidence in an estimated POD, lower botind values of this probability at a given confidence level are...

report 1984

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Application of model following control and estimation techniques to attitude control of manoeuvring spacecraft Part I: Theory and simulation results

Zwartbol, T. (author), Terpstra, A.P. (author), van Woerkom, P.T.L.M. (author), van den Dam, R.F. (author)

This document presents an approach to sampled data, on-board estimation and control of the attitude motion of manoeuvring spacecraft. Algorithms which are developed include: a - model following control of attitude manoeuvres b - estimation of spacecraft state (attitude, angular velocity, disturbance torque) c - optical-inertial attitude...

report 1982

document

Two-dimensional flight-path reconstruction by means of spline approximation

Beste, M.R. (author)

In this report, a method is developed to reconstruct the flight-path of an aircraft in symmetric, non-steady flight by representing this path by a set of splines. That set of splines is chosen, for which the flighttest data are best explained in some weighted least squares sense. This leads to a large, sparse, nonlinear, overdetermined system,...

report 1982

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Functional requirements for a software cost database

Dekker, G.J. (author), van der Wilt, M. (author), van den Bosch, F.J. (author)

Cost estimation of software development and control of the cost during the development, are difficult due to the lack of useful cost figures from previous projects, and consequently due to the lack of an accurate cost estimation and management method. This report describes the results of the first phase of a study to develop a software cost...

report 1981

document

On martingales and recursive optimal state estimation

Moek, G. (author)

This report constitutes the deposit of a study of literature on martingales and estimation theory. Some experimental work concerning the efficiency of an estimation algorithm based on martingales is also described. The investigation has been guided by the intent to investigate martingales in relation to the Kalman and Kalman-Bucy filters and to...

report 1980

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Study of an attitude acquisition measurement technique using the ESA starmapper: Part I: Executive summary

van Woerkom, P.Th.L.M. (author), Sonnenschein, F.J. (author)

The study deals with the rotational motion of a spin-stabilized spacecraft equipped with a V-slit sun sensor and the X-slit ESA starmapper. Assuming complete absence of an a priori attitude estimate, it is required to produce a rough estimate of the spacecraft attitude motion. It was assumed that sensor misalignments, external torques and...

report 1979

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Study of an attitude acquisition measurement technique using the ESA starmapper: Part two: final report

van Woerkom, P.Th.L.M. (author), Sonnenschein, F.J. (author)

The study deals with the rotational motion of a spin-stabilized spacecraft equipped with a V-slit sun sensor and the X-slit ESA starmapper. Assuming complete absence of an a priori attitude estimate, it is required to produce a rough estimate of the spacecraft attitude motion. It was assumed that sensor misalignments, external torques and...

report 1979

document

Digital filtering methods, with applications to spacecraft attitude determination in the presence of modelling errors. Part II: Extension of theory, and applications

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

document

Processing of Meteosat attitude measurement flight data and evaluation of the performance of an adaptive filtering technique

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