The main subject of the present invention are solid compounds capable of generating hydrogen by a self-sustaining combustion reaction. The directional hydrophones are equidistantly spaced about the acoustic projector. The failover procedure uses a packet origin table built automatically from incoming packets and from double-tunneled ARP requests. The protrusion and the opening are disposed between the first weld mark and the second weld mark on an imaginary straight line connecting the first weld mark and the second weld mark. The cathode plate is insulated with a shielding cover, and a through-hole is configured on the shielding cover.