Abstract: The invention relates to a device for recovering heat from the environment, for use in underground and underwater construction, wherein in a sheet piling wall (2) anchored in a subgrade and made of sheet piling wall elements (4) that can be locked to each other, the sheet piling wall elements (4) comprise at least one closed hollow space (6) designed as a heat tube (8), wherein the heat tube (8) transfers heat energy drawn from the water or the ground via the sheet piling wall elements (4) to a heat pump (16) via a heat exchanger (12) at the one end (14) of the heat tube (8).

Abstract: The invention relates to a device for speed measurement with two sensors arranged at a predetermined distance from each other in a direction of movement of an object and arranged at a distance from the surface of the object, which emit signals to an evaluation device with two input channels, the evaluation device being a delay correlator which digitizes the signals occurring at its input channels and forms a closed control loop for determining the time shift of the signals emitted by the sensors, the control loop having a phase detector for a comparison of the time shift of input signals, a controller and an adjusting circuit for the controlled variable or parameter to be controlled by the controller, the delay correlator having a shift register of a constant length and variable clock frequency, wherein a phase comparison of the instantaneous values of the digitized signals of the two sensors, one of which is delayed by the controller, can be performed by the phase detector, the clock frequency of the shift r