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The ecosystems of the rivers Rhine and Meuse have suffered drastic environmental changes, for example because of the regulation of the stream bed and the construction of weirs and dams. Furthermore, discharges of industrial and municipal waste water have caused the water quality of these rivers to deteriorate; this problem became acute in the sixties and(More)
This paper describes a class of multibeam synthesis algorithms that are useful for large arrays when simultaneous nulling of interference is required. In these algorithms, the computational cost is kept small by using fast Fourier transform (FFT) beamforming, while at the same time interference is nulled using spatial projections. Once the interference(More)
Some properties of five bream populations and their habitats have been studied. A number of preliminary results are discussed. 1. Bream population densities stabilize at a certain level, depending on habitat properties. 2. The growth rate of bream is to a large extent conditioned by the relative availability of zoobenthos. 3. Poorly grown bream can raise(More)
We discuss the use of a sparse fractal phased array antenna to be used in an aperture synthesis array with over forty of such antenna stations. The multi-beam phased array approach offers a solution that potentially allows effective suppression of man-made signals from the received sky noise as to detect astronomical objects that are even 70 dB weaker. Key(More)
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