Abstract: The circuit arrangement has a key for the serial feeding in of the code signals and is equipped with electronic arrangements for the storage of the code and for the processing of the signals. In the beginning or at the end of each sampling, a signal is produced and the temporal intervals between these signals are identified as "long", "medium" or "short." The sequence of these signal intervals, that is, the signal pauses, is compared with the stored code.Such a code may be remembered with particular ease as the rhythm of a song or as a melody and is accordingly very personal code. The feeding-in of the code and especially the decoding is acomplished "blindly", that is without return communication.In order to carry out the individual functions, separate construction stages or a microcomputer can be used.

Abstract: To measure the heat flow and the mass flow in a conveying system for fluids, a device is used which consists of (i) two fluid-carrying tubes, one mounted in the feed line and one in the return line, (ii) a heat-conducting section between these two tubes and (iii) temperature sensors. The heat-conducting section is made of material of low thermal conductivity, e.g., glass or a composite such as enamel or plastic-coated steel. It is designed such that the heat transmission through the heat-conducting section is lower than the heat transfer at the two interfaces between the fluid and heat-conducting section. At or close to the ends of the two heat transfer zones in the feed and return lines the temperatures or temperature differences of the fluid are measured and the heat flow or mass flow is derived from the results of these measurements.