The present invention concerns a high melt strength propylene polymer or copolymer suitable for manufacturing foams and thermoformed product exhibiting a melt strength of at least 3 g and comprising a high molar mass portion and a low or medium molar mass portion. The cooker has a main body having an upper cover, and receives an inner pot. The primary coil is electrically connected to the source of alternating current voltage. A subset of the rings including one or more common rings that are connected to both the ingress and egress ring nodes is identified. A pressure from paper sheets stacked on a paper tray of the automatic paper feeder is detected by a paper tray pressure detecting mechanism and transferred to a roller pressure adjusting mechanism to change a pressure between the paper feeding roller and a paper separating plate and adjust a feeding angle of the movable paper tray. As the concrete shrinks during hardening, the self-release elements of the connectors allow the joint to freely open.