Peiling nationale kennisbehoefte straling en nucleaire veiligheid

In a report issued in 2008, the Health Council of the Netherlands noted that the scientific knowledge on radiation protection was seriously in decline. This statement is still valid nowadays. It is therefore important to collate existing radiation knowledge, to make state-of-the-art expertise available to government and society and to acquire...

Some numerical aspects for solving sparse large linear systems derived from the Helmholtz equation

In this report, several numerical aspects and diculties for solving a linear system derived from the time-harmonic wave equations are overviewed. The presentation begins with the derivation of the governing equation for waves propagating in general inhomogeneous media. Due to the need of numerical solutions, various discretizations based on...

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...

Test loops for two-phase thermal management system components

Two mechanically pumped two-phase test rigs were built at NLR in order to experimentally study critical issues of spacecraft two-phase thermal management systems: - a 5 kW, 31 mm ID, freon loop, focusing on the critical components of the ESA Two-Phase Heat Transport System. - a 30000 W, 4.93 mm ID, ammonia loop, to support the development of the...

Feasibility demonstration of a sensor for High-Quality two-phase flow

Two-phase flow heat transport systems for the Columbus Space Platform and the Space Station are expected to incorporate systems to control the liquid flow rates into evaporative cold plates. Candidate components for such a control system are sensors monitoring the (very high) mixture quality at the cold plate exit lines, control algorithms and...

Considerations concerning a thermal joint for a deployable or steerable battery radiator for the Columbus Polar Platform

Different concepts for a moveable thermal joint are described and discussed with respect to the applicability in a dedicated deployable or steerable heat pipe radiator system to handle the waste heat of the NiH batteries of the Polar Platform. Concepts which are identified as possible candidates for near-term deployable radiator development are:...

A mathematical model of uniform longshore currents and the comparison with laboratory data

This report describes a mathematical model for uniform longshore currents and laboratory experiments on these currents, as also the comparison of theory and experiment. The longshore driving force is modeled taking into account the physical fact that dissipation of wave energy takes place shoreward of the plunge instead of in the whole surf zone...

Theoretical and computational aspects of adaptively controlled Navstar antennas

Wave Heights and Set-up in a Surf Zone

A theoretical model is developed for wave heights and set-up in a surf zone. In the time averaged equations of energy and momentum the energy flux, radiation stress and energy dissipation are determined by simple approximations which include the surface roller in the breaker. Comparison with measurements shows good agreement. Also the...

Analysis of possible interference in radio altimeters induced by a position marker system called RASP

An analysis is given of possible interference induced by a position marker system, called RASP, into aircraft radio altimeters. The RASP system is used as a marker beacon in flight tests for trajectory measurements, and operates on 4.3 GHz. It is concluded that radio altimeters will not experience any harmful interference from a RASP transmitter.

Movable-Bed Laboratory Experiments Comparing Radiation Stress and Energy Flux Factor as Predictors of Longshore Transport Rate

Three-dimensional movable-bed laboratory tests were conducted to compare radiaton stress and energy flux factor as predictors of the longshore sediment transport rate. The tests were performed in the U.S. Army Coastal Engineering Research Center's (CERC) Shore Processes Test Basin (SPTB). This report presents derivations of the radiaton stress...

Measurement of radiation patterns of aircraft antennas in non-steady flight

Instationary methods in measuring radiation patterns of aircraft antennas are described.

Multiple attitude maneuvers for a spinning spacecraft disturbed by solar radiation

The attitude motion of interplanetary, spinning spacecraft under the influence of solar radiation and optimal thrusting, is investigated. A general model is formulated to describe the forces and torques exerted on the spacecraft due to solar radiation. The model is compared with model! available in the large body of literature on the subject. It...

Het meten van lichtreflecties van gewassen

Measurement of an object's reflectance spectrum can provide information on its nature and qualities. However, one should thoroughly take into account the fact that in general the reflectance spectrum does not only depend on the object itself, but also on the parameters defining the measurement conditions, like the spectral and spatial...

Sound transmission in and radiation from hard-walled annular ducts related to fan engine inlets

In this report the sound propagation in a hard-walled annular duct of finite length is investigated. The individual modal solutions so found are described. The main properties which are calculated in the present report, are the modal intensity and the modal far field directivity pattern. The modal intensity is determined by the rate of mode...

Littoral drift computations on mutual wave and current influence

11th Conference on Coastal Engineering in London 1968, the author presented a method for computing the littoral drift starting from the longshore current velocity as this is generated by the waves and with the assumption that the material is stirred up by the waves. In this paper measurements in a model basin are described by which the procedure...

Increase of bottom shearstress of a current due to wave motion

Due to the increased velocity vector in the case of current combined with waves the bottom shear stress in the direction of the current will increase. This increase has been derived and the derivation has been checked by measurements.