Abstract: Method of measurement of knee strength characteristics is carried out in a manner that measured person in upright position leans against dynamometers with bearing surfaces (3) and movable arm (2) and starts transition to the sitting position, thus acting on the movable arm (2), which through connected sensor (21) of angular position monitors speed of change in angular position of the movable arm (2) and acts on dynamometers with bearing surfaces (3), which measure strength generated by measured person for each lower extremity individually, whereas sensor (21) of angular position and dynamometers transmit collected data to control unit, which evaluates speed of change in angular position of movable arm (2) and visualization equipment (4) shows to measured person actual and requested speed of change in angular position of movable arm (2) in a manner that measured person adjusts speed of transition from upright to sitting position to requested speed.

Abstract: A circuit for performing a method melting vitreous materials in an electric furnace wherein the electrodes are supplied with an alternating current of optimal frequency lower than 60 or 50 Hz, respectively, the corrosion of electrodes being minimized. The circuit comprises a cycloconverter which changes a three-phase current supply into a single-phase current with a simultaneous changing of the input mains frequency into an optimal output frequency. The circuit also comprises a device for measuring and/or controlling the direct current component of the low frequency feeding alternating current, in order to stabilize the favorable anticorrosion effect of the low optimal frequency. Further, it comprises a device for the control of the power input of the cycloconverter with respect to the melting temperature in the furnace.