Abstract: The invention puts forward a bidirectional DC-DC converter for high voltages that is as simple as possible and that entails as few losses as possible. The bidirectional DC-DC converter (1) converter comprises an input stage (2) to convert a DC input voltage into first AC voltage, a transformer (3) to transform the first AC voltage into a second AC voltage, and an output stage (4) to convert the second AC voltage into a DC output voltage, whereby, in order to provide the first and/or second AC voltage, at least one of the input stages (2) and/or output stages (4) comprises a branch of a multi-level converter (5) with a first number of active first semiconductor switches (61).

Abstract: There is provided a method for the activation of a fuel cell. An exemplary method comprises operating the fuel cell entirely or partially at least briefly in an electrolysis regimen during galvanic operation.

Abstract: The invention relates to a device for determining the mechanical leg axis of a femur. Said device is provided with a shaft (3) that comprises, on one of its ends, a securing device (5) that is connected to the shaft and that can be blocked at various angles, in order to obtain a fastening that can be blocked in an angle stable manner and that fastens the shaft (3) to the knee joint of a femur, and comprises a gripping element (10) on its other end. A force-torque measuring device (14) is arranged between the gripping element (10) and the shaft (3), said device enabling the longitudinal and/or transversal force components of force (Fz) exerted via the shaft (3) upon the knee joint to be measured by means of the gripping element (10) and/or torque produced thereby. The invention also relates to a method for determining the mechanical leg axis of a femur by means of the above mentioned device.

Abstract: The invention relates to a device for determining the mechanical leg axis of a femur. Said device is provided with a shaft (3) that comprises, on one of its ends, a securing device (5) that is connected to the shaft and that can be blocked at various angles, in order to obtain a fastening that can be blocked in an angle stable manner and that fastens the shaft (3) to the knee joint of a femur, and comprises a gripping element (10) on its other end. A force-torque measuring device (14) is arranged between the gripping element (10) and the shaft (3), said device enabling the longitudinal and/or transversal force components of force (Fz) exerted via the shaft (3) upon the knee joint to be measured by means of the gripping element (10) and/or torque produced thereby. The invention also relates to a method for determining the mechanical leg axis of a femur by means of the above mentioned device.

Abstract: A device (10) for acquiring data in the mouth of a patient, wherein the device (10) comprises an ultrasound sensor (20) and a support structure. The ultrasound sensor (20) is stored by means of the support structure when not in use and contains ultrasound deflection means (12) which are movable. A coupling body (21) is provided, which is arranged between the ultrasound deflection means (12) and a tooth area (1, 2, 3) or remaining tooth area to be swept over Excitation signals (14) are sent to the ultrasound sensor (20) and the ultrasound deflection means (12) are moved in order to thus produce an ultrasonic wave which sweeps over at least part of the tooth area (1, 2, 3) or remaining tooth area.