Methods and apparatus for analyzing tasks performed by computer users by gathering usage data, converting logged usage data into a uniform format, determining or defining task boundaries, and determining a task analysis model by \u201cclustering\u201d similar tasks together. The drum core includes a core, a first flange and a second flange disposed on both ends of the core. During the tire build-up, an accumulation of rubber material of higher electrical conductivity is built on a first rubber layer of higher electrical conductivity.