Abstract: To ensure that a camouflage structure will not lose its effectiveness even in changing temperatures (day/night, sunshine/clouds) when protecting against reconnaissance in the IR range, the camouflage structure features varying emissivity tendencies in the atmospheric windows II (3-5 um) and III (8-14 um). In other words, the emissivity in the IR range is not constant and at a certain level, but it has an increasing or decreasing tendency in at least one selected spectral range.

Abstract: The material exchange column contains a packing which can be installed in the horizontal position of the column. The column has a ring gap between the packing and the column wall in which collars are arranged. The latter each comprise a band-shaped region (30) which lies in contact with the packing. At the upper edge of the band-shaped collar regions there adjoin spring-elastically connected surface pieces which produce a bridge to the wall and which are provided for a return conduction of the liquid from the wall to the packing during the operation of the column. It applies at least for some of the collars that the latter have elevations in their band-shaped regions which hold the ring gap open in a form-stable manner under the load of the packing when the column lies horizontally.