Abstract: The present patent application describes an approach to the protection of voltage sensitive instruments using a protection circuit that may be easily integrated in a three-terminal device, and which overcomes the drawbacks of previous approaches. The protection circuit of the invention performs very fast against overvoltages (in a few nanoseconds), automatically switching to a low impedance conduction state as soon as the overvoltage situation ends. It also minimizes insertion losses, shows a very low level of thermal noise and allows for obtaining broad bandwidths due to its low serial impedance in the conduction state. Furthermore, it does not require any power source or control signal.

Abstract: The invention relates to a beam former which performs coherent composition of signals originating from a given propagation direction, which are received by an array of <I>N </I> receiving transducers. The inventive methodology and devices are suitable for use in the following fields: radar, sonar, acoustic, seismology, ultrasound imaging (echography and non-destructive testing) and others. According to the invention, the beam former employs arrays having elements which can be distributed randomly. In particular, the invention can be used for dynamic focusing with deflection of the beam in azimuth and elevation, using two-dimensional arrays.

Abstract: An installation for the automatic evaluation of the condition of the rolling band on wheels of moving trains. It comprises a rail beam (1) for each railway line (8), a guard-rail to assure wheel guidance, feelers (P1, P2, P3, P4) intended to come into contact with the wheels passing over them, feeler holders fitted on the rail beam, to ensure wheel-feeler contact, ultrasonics equipment (12) to transmit ultrasonic pulses towards the wheels and to generate the corresponding ultrasonic plots, a local processor (13) to control the ultrasonics equipment and to receive the ultrasonic plot signals generated, a computer (14) connected to the local processor to manage the ultrasonics equipment, and an antenna (15) connected to the computer to identify the compositions of train measurements. The invention is useful to detect cracks in the rolling band of railway vehicle wheels.