A process for removing a modulation sinusoidal error from signals of a rotating load cell measuring forces andor moments with respect to a non-rotating orthogonal coordinate system includes mounting the load cell to the rotating object and obtaining a first set of signals from the load cell, wherein at least one signal of the first set of signals is indicative of a load as the object rotates. According to a preferred embodiment of the method of the invention, a determination function of speed and temperature is provided. According to the present invention, an air filter sheet comprising fibrils of polytetrafluoroethylene resin with a functional agent carried thereon, possessing excellent formability, and being free from a lubricant, a process for manufacturing the air filter sheet, and an air filter free from contamination of outgas with a lubricant are provided. Physical properties may be used to model the physical quantities of each system. An associated method is also provided.