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ten Dam, A.A. (author), van den Berg, J.I. (author)
The mathematical modelling and numerical simulation of a condenser is discussed. This mathematical model is part of the NLR approach to model and scale two-phase heat transport systems (for space). During a previous study the condensation length required for various gravity conditions, and working fluids has been investigated by means of...
report 1993
document
Noback, R. (author)
Aspects of the requirements for and the calculation of design loads due to atmospheric disturbances are discussed. Special attention has been paid to the relation between discrete gusts and continuous turbulence. It is recommended that a worst case gust model, as described in this report, be further developed.
report 1993
document
Noback, R. (author)
A worst case gust shape has been derived for turbulence or gust patches, assuming only that the average spectrum of such patches is known. The maximum value of the response can be calculated quite easily. The result differs from the PSD-method. Some examples of worst case inputs and outputs are given, also for nonlinear systems.
report 1993
document
Groothuizen, R.J.P. (author)
An inverse robot kinematics method is being developed that is to be applicable to any sequential rigid robot. In this report, first requirements are identified and a survey of existing methods is given. An. evaluation of these methods with respect to the requirements then shows that a method based on optimization is the best candidate. It...
report 1990
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van der Wees, A.J. (author), van den Berg, J.I. (author)
NLR mainly performs applied scientific research for use in the aerospace industry. In many cases the product has the form of an information system for the design, production and usage of aerospace vehicles. Within this context, the mathematician contributes, in cooperation with specialists from other disciplines such as aerodynamics, structures,...
report 1990
document
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
document
van Woerkom, P.T.L.M. (author), Steenman, G.J.J. (author)
The objective of the study is the synthesis of an algorithm for the automatic control of an electromechanical actuator in the rotational joint of a multi-link, robotic manipulator. Control performance is assessed in terms of ability of the controlled joint to follow a commanded joint angle, or a commanded joint angular rate. Part One of the...
report 1988
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de Koning, A.U. (author), Liefting, G. (author)
The crack opening behaviour of a fatigue crack in a centrally cracked panel was studied using a discretised version of the Dugdale and Barenblatt model. The effect of crack growth was also included. Results obtain ed for constant amplitude loading were in agreement with data reported in the open literature. The effect of application of single...
report 1986
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van den Dam, R.F. (author)
The central issue discussed in this paper is how a designer may profit from the use of mathematical simulation and optimization techniques. These techniques can be useful tools to support the designer in solving his design problem. The place and the potential of these techniques in the design process, as well as their use by the designer, are...
report 1985
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van Woerkom, P.T.L.M. (author)
Mathematical models of the dynamics of spacecraft are needed to carry out numerical simulations, to gain insight into the characteristics of the spacecraft dynamics, and to synthesize control algorithms suitable for online system Identification, estimation, and control. Increases in size and mechanical complexity of spacecraft result in...
report 1985
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Milgram, P. (author), van de Graaff, R.C. (author), Wewerinke, P.H. (author)
This report is a tutorial overview for the European Space Agency (ESA) of human engineering approaches and methodologies which are applicable for analysis of performance of human-machine systems, with specific emphasis on space teleoperator applications. Motivated by the presumed active role of the human operator in future space teleoperation...
report 1985
document
Moek, G. (author)
A probabilistic model is described for the lateral displacement of an aircraft after the occurrence of an engine failure during take-off. With the model, a lateral boundary is calculated, for any point of time after the engine failure, such that the probability of being within the (two sided) lateral boundary meets a specified value. Various...
report 1985
document
van den Dam, R.F. (author)
The use of numerical simulation and optimization techniques is rapidly expanding in all fields of engineering design. The place and the potential of these techniques in the design process, as well as their use by the designer, are discussed. The principles underlying these techniques are outlined and an overall view is given of the various...
report 1985
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Vogels, M.E.S. (author)
One of the experiments performed on board Spacelab, involves a partially filled annular cylinder which is subjected to prescribed motions (Ref. 1). The interest in this configuration arises from its practical use; for instance, the coolant in IRAS was stored in an annulus-like tank. In this report, a mathematical model for the transient liquid...
report 1984
document
van de Graaff, R.C. (author), Wewerinke, P.H. (author)
This report deals with an investigation of pilots' failure detection performance in a realistic moving-base flight simulator. The task considered was the monitoring of stabilized automatic approaches. Abnormal conditions (excessive windshears or system failures) were to be detected on the basis of unacceptable deviations of displayed variables...
report 1984
document
Noback, R. (author)
In this report various methods to describe a landing gear with nonlinear properties and excitated by random runway unevenness during taxying have been investigated. The results of calculations have been compared to measured results from an analog computer simulation. The mean behaviour, standard deviations and power spectra, can be described...
report 1984
document
van der Linden, H.H. (author)
The GARTEUR Group of Responsables for Structures and Materials identified the need for an evaluation of fatigue crack propagation models. This resulted in a collaborative GARTEUR activity in which 13 variations of the F-27 transport spectrum were evaluated by 7 institutes and companies using in total 13 crack propagation prediction methods and...
report 1983
document
van Woerkom, P.T.L.M. (author)
Software design for digital computer simulation of the dynamics of flexible spacecraft equipped with actuators and sensors, should take into account two properties of the overall system: (i) s.ampled-data control of the spacecraft leads to discontinuous inputs (forcing functions) in the differential equations of motion, thereby requiring...
report 1983
document
Pool, A. (author)
This lecture reviews the model studies that were made with the object to reduce en-route separation standards. It also describes the basic principles of the Reich model used in most of these studies and of the Minimum Navigation Performance Specification (MNPS). Paper presented at the Princeton University Conference 155, "Safety Issues in Air...
report 1983
document
Loeve, W. (author), van den Dam, R.F. (author)
The NLR in the Netherlands renders scientific support and technical assistance for the design and operation of aircraft and spacecraft. The approach of NLR can be characterized by integration of experimental and theoretical investigations. For this an integrated computer and terminal network has been developed that links both NLR laboratory...
report 1983
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