Abstract: The invention relates to a heat exchanger for motor vehicles, especially for utility vehicles. The heat exchanger can include a heat exchanger unit that includes tubes having tube ends and ribs disposed between the tubes, and collecting tanks disposed on both ends and produced by internal high pressure forming for introducing and discharging a medium. The collecting tanks can include bottoms with openings for receiving the tube ends, covers, and inlet and outlet tubes.

Abstract: The invention relates to a heat exchanger for motor vehicles, especially for utility vehicles. Said heat exchanger comprises a heat exchanger unit (2), constituted of tubes (5) having tube ends and ribs (6) disposed between said tubes (5), and collecting tanks (3, 4), disposed on both ends and produced by internal high pressure forming for introducing and discharging a medium. Said collecting tanks (3, 4) comprise bottoms with openings for receiving the tube ends, covers and inlet and outlet tubes (7, 11).

Abstract: A method is described for examining a solidifying and/or hardening material such as cement, concrete or the like, using ultrasound waves emitted by an ultrasound transmitter, which penetrate the solidifying and/or hardening material, are continuously measured and analyzed. During solidification and/or hardening of the material, the signal shapes of the ultrasound waves penetrating the material, are recorded. The change with time of the compression wave velocity and/or the relative energy of the ultrasound waves and/or the frequency spectra of the ultrasound waves is extracted from the ultrasound wave shapes during the entire course of solidification and/or hardening of the material. This change with time of the compression wave velocity and/or the relative energy of the ultrasound waves and/or the frequency spectra of the ultrasound waves is approximated through a compensating function, preferably the Boltzmann function.