On-line superposition of geographical data to tiros-N type meteorological satellite images

A method is described, by which geographical data are superposed in real time to the high resolution HRPT imagery, received from the TIROS-N series satellites. The superposition of additional geographical data is important for an accurate position determination of the image data. Computations necessary for the transformation, conversion and...

Application of model following control and estimation techniques to attitude control of manoeuvring spacecraft Part II: Simulation software description

This document describes two computer programs developed during a study of the application of modern control techniques in the area of spacecraft attitude control. Theory and simulation results are described in part I of this report. In part II a general overview of the tasks of the simulation program is presented, and program design aspects are...

Experimentele vortex analysator

A measuring system is described for detection and analyses of aircraft wake vortices in the approach zone of a runway. This system consists of propeller anemometers, a data-acquisition unit, a quick-look monitor and a NOVA minicomputer with a real-time vortex detection program. A short description of aircraft wake vortices is also given. Some...

Aspects of second- and third-order panel methods demonstrated for the two-dimensional flat plate problem

Characteristics of three second-order and two third-order panel method formulations for the incompressible flow about a flat plate at incidence are investigated. The second order methods employ quadratic representations for the doublet distribution, either based on quadratic B-splines or on a combination of a Taylor series expansion and finite...

A finite difference method for the calculation of transonic flow about a wing, based on a small perturbation theory

A calculation method, based upon transonic small perturbation theory, is presented for the transonic flow about a semi-wing. The influence of a body can be simulated by prescribing appropriate transverse velocities in a vertical plane through the wing root. Due to the small perturbation assumption the wing should be thin and have little dihedral...

Dissemination of ERS-a low bitrate data and the use od L-band receiving stations

The dissemination of ERS-1 real-time thematic products via the Global Telecommunication System, the ECS satellite telecom system or the Eiuronet packet switching network is analysed and evaluated against the use of direct-receive L-band stations as used for NOAA weather image reception.

Gyro noise measurement and analysis

Noise measurements were performed on two identical space qualified gyroscopes of the floated rate integrating type (Perranti Type I25) in an analog rehalance loop configuration of selectable loop bandwidth, running under space representative conditions. The noise frequency range of interest was O.OO5 Hz to 50 Hz. The noise results were processed...

Influence of ambient air pressure on impact pressure caused by breaking waves

Engineers are interested in the dynamics of the interface waterstructure. In case of breaking of water waves on a structure high positive and sometimes negative pressures of very short duration occur. Not only the maxima and minima of the pressures on the structure are important to a designing engineer, but also the pressure-time history:...

Heat treatment studies of aluminium alloy forgings of the AZ 74.61 type. Interim report no. 3: Fatigue crack propagation performance under manoeuvre spectrum loading

The fatigue crack propagation performance of the alloy AZ 74.61 under manoeuvre spectrum loading was studied. The crack propagation behaviour was also compared with that of the American forging alloy AA 7050, not only for simulated manoeuvre loading but also for simulated gust loading and programme loading. It was found that, at comparable...

Image data security in the concept of the agricultural real time imaging satellite system (artiss)

The study on image data security is directed to the requirement for exclusive access to satellite imagery in the concept of the Agricultiiral Real Time Imaging Satellite System (ARTISS). The security assessment indicates that user survey requests are handled confidentially and it shows the access vulnerability of the transmission of image data...

Survey of modern control and observation theory for disturbed, target following aerospace systems. Part one: Basic theory

The document contains a general theory towards the observation and optimal control of disturbed, target following aerospace systems. Disturbed, target following aerospace systems eire defined as aerospace systems that are designed to track a moving target system, while they are subjected to external, time-varying disturbances. The first five...

An hierarchic multi-suppliers computer network of a research laboratory with two settlements

For the aerospace laboratory NLR in the Netherlands the considerations are discussed that formed the basis of along-term plan to realize an optimal computer network. In the optimization process up to now the laboratory switched from a situation in which in each of both settlements one central close shop computer centre was available to a...

Multiband OFDM for Covert Acoustic Communications

A multiband OFDM transmitter and receiver are presented for underwater communications at low SNR. Compared with a single-band OFDMscheme, the multiband approach leads to a considerable reduction in the receiver complexity. The proposed system has been tested at sea with 16 subbands covering a total bandwidth of 3.6 kHz, at user data rates of 4.2...

Configurbanist: Urban Configuration Analysis for Walking and Cycling via Easiest Paths

In a quest for promoting sustainable modes of mobility, we have revisited how feasible and suitable is it for people to walk or cycle to their destinations in a neighbourhood. We propose a few accessibility measures based on an 'Easiest Path' algorithm that provides also actual temporal distance between locations. This algorithm finds paths that...

The online chemical analysis of single particles using aerosol beams and time of flight mass spectroscopy

This paper describes an on-line instrument, capable of measuring the size and chemical composition of single aerosol particles. Possible applications include monitoring aerosol reactors and studying atmospheric chemistry. The main conclusion is that a working prototype has been built and tested. It uses a three stage vacuum system to generate an...

Factors influencing the residence time of catchment waters: A virtual experiment approach

Estimates of mean residence time (MRT) are increasingly used as simple summary descriptors of the hydrological processes involving storage and mixing of water within catchment systems. Current understanding of the physical controls on MRT remains limited, and various hypotheses have been proposed to explain its variability between catchments. We...