Abstract: A quality value for a carbon ceramic brake disc (2) in a vehicle is measured by means of a measuring device (3) installed in the vehicle. The measuring device (3) with a coil (10) is located at a distance (d) from the brake disc (2) in order avoid direct physical contact with the brake disc. The impedance of the coil (10) is measured for at least two frequencies. The resulting measurement values that correlate to impedance values are introduced into a mathematical model in order to eliminate the dependence of the unknown distance (d) and to obtain a quality value dependent on the conductivity of the brake disc (2).

Abstract: The device for the impedance-based probing of materials described herein comprises a two-dimensional array of coils (1) and a measurement unit (4) adapted to determine, for each coil (1), a parameter indicative of its impedance. A pulse generator (3) is able to generate current pulses in each coil (1). The circuitry drives and senses the coil array through row and column lines (rp1 . . . rpN1, cp1 . . . cpN2, c21 . . . csN2) in order to minimize the number of required components. The device can, in particular, be used for probing concrete.

Abstract: The device for the impedance-based probing of materials described herein comprises a two-dimensional array of coils (1) and a measurement unit (4) adapted to determine, for each coil (1), a parameter indicative of its impedance. A pulse generator (3) is able to generate current pulses in each coil (1). The circuitry drives and senses the coil array through row and column lines (rp1 . . . rpN1, cp1 . . . cpN2, c21 . . . csN2) in order to minimize the number of required components. The device can, in particular, be used for probing concrete.

Abstract: Device for determining wear in a carbon ceramic brake disk. The device includes a coil arrangement having at least one coil structured and arranged to generate a magnetic field in the brake disk and to detect an eddy current in the brake disk, and an arcuate measuring area.

Abstract: Device for determining wear in a carbon ceramic brake disk. The device includes a coil arrangement having at least one coil structured and arranged to generate a magnetic field in the brake disk and to detect an eddy current in the brake disk, and an arcuate measuring area.

Abstract: An apparatus and a method are described that determine the compressive strength of a solid by rebound. The method and apparatus have a reduced sensitivity to error sources, i.e. gravity, internal friction and operator interference (unsteady holding of the instrument). The improvements are achieved by contactless measuring of the quotient of rebound to inbound velocity recorded immediately before and after the impact. Matching the mass of the mallet (3) to the plunger (5) yields higher efficiency, less angular variation of the impact energy and lighter weight. Added benefits of the invention are: Extended range of measurement and simplified mechanical adjustments, calibration and maintenance.

Abstract: A method of, and apparatus for, testing the hardness of a material by means of an impact device wherein an impact body having a test tip or point which is either integrated, e.g., connected with, or separate from, the impact body is brought to impact against the material to be tested. There is determined the velocity of the impact body and/or the test tip both directly before and after impact, and there is then formed a characteristic value from both velocities which is utilized as criterion for the hardness of the material.