Accuracy of modal frequency set with fictitious joints modelling

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...

Modelling and simulation of a rate controlled manipulator ARM

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...

Preliminary model for the blunt notch behaviour of fibre metal laminates

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...

A model of the human decision maker observing a dynamic system

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...

Hybrid equations for translational and rotational motion of flexible spacecraft

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...

The acoustics of a lined duct with flow

The present report describes a theory to calculate the sound propagation (including attenuation, reflection, radiation) through a three-sectioned cylindrical flow duct, modelling an aero-engine inlet. The flow is uniform apart from a thin boundary layer; two of the three sections are hardwalled, with an impedance-walled section in between. The...

Approximate confidence regions for the parameters of three software reliability models

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...

The effect of visual information on the manual approach and landing

The visual scene is an important source of information for the manual approach and landing task. This study deals with the effect of this information in combination with basic display information on the manual approach performance. In this context, a pre-experimental theoretical analysis has been performed in terms of the optimal control model....

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

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....

Theoretical investigation of the basic thermal performance of multilayer insulation blankets

The thermal performance of evacuated multilayer insulation blankets depends on three modes of energy transfer: radiation between the radiation shields, gas conduction m the residual interstitial gas and solid conduction via the contacting interfaces. The importance of the contributions of the three heat transfer modes depends on many parameters...

Numerical simulation of a condenser in two-phase heat transport systems a feasibility study

In this report the numerical simulation of a mathematical model of a condenser is discussed. This mathematical model of the NLR approach to model and scale two-phase heat transport systems. In this report the model of the condenser is reformulated to a model that is suitable for a numerical discussion. The results is a model that is represented...

An improved flat front model for a gas loaded variable conductance heat pipe

A uniaxial flat front--"theory is presented for a gas loaded variable conductance heat pipe. The theory takes into account the inertial effects of the moving vapour, which can grow large under certain circumstances, but neglects the axial heat conduction of the wall and wick. A limited number of numerical examples indicates excellent agreement...

A method for applying linear optimal control theory to the design of a regulator for a flexible- aircraft

This report deals with determining a hypothetic control system which provides improved rigid body and structural mode damping of a flexible aircraft in order to improve the riding qualities and to minimize the wing bending moment during flights in turbulence. The equations of motion used in the computations are related to a high' performance...

An ALGOL-program for the calculation of incompressible three-dimensional turbulent boundary layers

A computer program has been prepared for the calculation of turbulent boundary layer development, based on a 3-D version of the turbulent energy method. The method is briefly discussed. The computer program is described in detail. The present program is restricted to developable surfaces.

Experimental pressure wave research at NLR for high-speed rail tunnels

Pressure waves, that are generated when a high speed train enters a tiinnel, can cause annoyance to train passengers (rapid pressure fluctuations acting on the train) and for people living near the tunnel (micro-pressure wave). To improve train passenger comfort the effect of various pressure relieving measures (i.e. shafts and porous walls)...

Axisymmetric liquid sloshing under low-g conditions: numerical simulations method (-reference manual-)

A mathematical model is presented for the description of axisymmetric three-dimensional transient flow of a viscous liquid in a partially filled cylindrical container under low gravity conditions. The mathematical model consists of the Navier-Stokes equations with either no-slip condition at the solid boundaries, and with the continuity of...

PROCRU simulation results compared with Metro II in-flight ILS approach data

The PROCRU (Procedure Oriented Crew) model has been developed for the analysis and modeling of flight crew procedures during an ILS approach. The model's specific capability concerns the generation of "timelines" of the necessary actions to be carried out by each crew member during the approach. Besides, also the corresponding timelines for...

The response of aircraft to two-dimensional vertical turbulence

Equations for the response of an aircraft to two-dimensional vertical atmospheric turbulence have been derived, both for an aircraft regarded as a continuous system and for an aircraft split up into a number of panels. These equations have been applied to an aircraft model with two degrees of freedom of the size of the Fokker 100, respectively....