Abstract: A method detects a bird or an object flying level with a single wind turbine, using a device for radio wave detection of at least one bird or another flying object, in the form of at least one radar. The analog image from each radar is transformed into a digital image and an outer safety area and an inner safety area is defined for the image. A safety space for each radar is defined and an action is performed in the event of a detection within the safety areas.

Abstract: A method detects a bird or an object flying level with a single wind turbine, using a device for radio wave detection of at least one bird or another flying object, in the form of at least one radar. The analog image from each radar is transformed into a digital image and an outer safety area and an inner safety area is defined for the image. A safety space for each radar is defined and an action is performed in the event of a detection within the safety areas.

Abstract: Porous particles of MgCl.sub.2 which have essentially the shape of two truncated right cones connected by their larger bases, which truncated cones are incurved towards the axis of symmetry perpendicular to the bases, at the intersection of the envelope of the truncated cones with two orthogonal planes passing through the said axis of symmetry. These particles are impregnated with a transition metal compound and employed as a catalytic component in the polymerization of olefins. The resultant polyolefins, especially polyethylene, polypropylene and their copolymers, are comprised of particles with a distinctive structure.

Abstract: Porous particles of MgCl.sub.2 which have essentially the shape of two truncated right cones connected by their larger bases, which truncated cones are incurved towards the axis of symmetry perpendicular to the bases, at the intersection of the envelope of the truncated cones with two orthogonal planes passing through the said axis of symmetry. These particles are impregnated with a transition metal compound and employed as a catalytic component in the polymerization of olefins. The resultant polyolefins, especially polyethylene, polypropylene and their copolymers, are comprised of particles with a distinctive structure.

Abstract: A process and apparatus for the automatic correction of the focusing of a microscope in an image plane utilizes two microscope outputs forming two images of the same object in two different planes surrounding the image plane and two matrices with at least one line of N photodetectors receiving the two images. A contrast measuring circuit of each image is associated with each matrix and a comparator of the signals is used for the two contrast measuring circuits. Connected to the output of the comparator is a circuit for the formation of a correction signal and the microscope is focused by the correction signal.

Abstract: The method consists in generating an electrical signal B which is representative of the time-dependent variations in transparency, in generating a pulse at the initial instant of measurement, in carrying out an initial measurement of the slope of the curve at the beginning of the portion which has a steep slope, in comparing at predetermined instants the measured value of the initial slope with the slope of the curve which is representative of the signal B at these instants, in generating a second pulse when the measured slope becomes significantly different from the initial slope, and in measuring the time interval which elapses between the first and second pulses.