Abstract: A piezo actuator in a monolithic multilayer design, has at least one piezoelectrically active stack element, wherein the stack element has stacked piezoceramic layers made of piezoceramic material and electrode layers arranged between the piezoceramic layers, at least one piezoelectrically inactive terminating region arranged above the stack element, and at least one junction region arranged between the stack element and the terminating region, wherein the stack element, the terminating region and the junction region are connected to one another to form a monolithic total stack. The junction region has stacked piezoceramic layers and electrode layers arranged between the piezoceramic layers, and the piezoceramic layers and the electrode layers are in a form and are arranged on one another such that in the stack direction of the junction region one piezoelectrically active area per junction piezoceramic layer is successively changed from piezoceramic layer to piezoceramic layer.

Abstract: The generation of dust in a longwall mining operation is suppressed by covering the hanging wall of the mine with a plastic sheeting, the sheeting being pinned against the hanging wall by the support units used in the mine and being held in association the support units in the form of a flat package formed by folding the sheeting in a zigzag fashion along its entire length.