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Laan, J.N. (author), Schulten, J.B.H.M. (author)The present status of a method to calculate the generation, transmission and radiation of fan noise is described. A steady uniform flow is assumed in the whole field. A hard-walled circular duct is considered which is terminated at the open end by an infinite baffle. The source mechanism is the impingement of wakes from an upstream blade row...report 1978
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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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van Woerkom, P.T.L.M. (author)If one wishes to simulate the djmamics of a structurally flexible, mechanical system with the aid of rigid body software, one may be tempted to use the "fictitious joints" modelling technique recently advocated In literature. The technique is believed to be promising in the case of flexible, slender beams, such as some of the links of a space...report 1987
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Guelman, M. (author)The mathematical model of a space based manipulator arm with a rate controlled end effector is defined and the recursive algorithms for the computation of the basic djmamic functions are formulated. A digital simulation of this system is implemented and preliminary results are presented. Actual running times for the simulation In a VAX 750...report 1986
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van Rijn, J.F.C.N. (author)A number of experiments were done to investigate the influence of plasticity on the strain distribution in the vicinity of a notch and the occurrence of local failure for ARALL3 plate specimens. Analysis of the results led to the development of a model for the blunt notch behaviour of fibre metal laminates. A preliminary implementation was...report 1994
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Delil, A.A.M. (author)A uniaxial model for the transient performance of gas-loaded variable conductance heat pipes is being developed, partly under contract with the Netherlands Agency for Aerospace Programs NIVR. The model has to be easily implementable in existing spacecraft thermal analyzer computer programs. So far, a steady-state version of the model is...report 1984
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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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Wewerinke, P.H. (author)The study described in this report was aimed at assessing the potentials of the optimal control model structure to predict the important characteristics of realistic operational helicopter missions. The theoretical and experimental results indicate that the optimal control model succesfully predicts the best attainable (rather than the average)...report 1977
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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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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
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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
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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 der Wilt, M. (author)The capacity of runways in use for landing aircraft may become the chief bottleneck of the capacity of airports. This runway capacity may result in long queues of aircraft waiting for landing, which in its turn results in unacceptable delays. Two analytic methods to determine these delays are described and the results are compared. The two...report 1977
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van der Vooren, J. (author), Delil, A.A.M. (author), Sanderse, A. (author)A new uniaxial model for a gas loaded variable conductance heat pipe (VCHP) is developed. This model takes into account the diffusion at the vapour-gas interface as well as the inertial effects of the moving vapour. Only steady-state conditions are considered. The generally accepted Edwards /Marcus model will be shown to be a first order...report 1980
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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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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
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Wewerinke, P.H. (author)In this report a model of the human observer and decision maker is described. A submodel of the human observer is formulated in linear estimation theoretical terms including the perception of the displayed information of a linear process and the central information processing stage. The subsequent decision process is described in terms of...report 1981
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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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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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van Woerkom, P.T.L.M. (author)The report deals with the equations of motion of spacecraft with rigid main body, flexible appendages, and rotors and jets on the main body. The hybrid coordinate modelling method is applied. The resulting equations describe the translational motion of the spacecraft, the rotational motion, and the coupling between these two types of motion. The...report 1981