Abstract: A method of measuring cell size of an open cell foam sample is provided including the step of providing an amount of a material suitable for obtaining foam sample impressions upon at least partial hardening in a vessel. A foam sample is placed on a surface of the material prior to hardening of the material. The foam sample is peeled away from the material after the material has begun to harden in order to provide a three-dimensional impression of at least a layer of the foam sample including a plurality of partial spherical impressions corresponding to cells of the foam sample. The cell size is measured by measuring a diameter of a plurality of the partial spherical impressions.

Abstract: A counter (24) increments several times during the duty cycle of a microprocessor (10), and a comparator (30) connected to both outputs a High signal when the microprocessor output exceeds the counter output and outputs a Low signal when the counter output is at least the microprocessor output. The microprocessor output is proportional to desired motor speed for an elevator door drive motor according to a velocity profile stored in a ROM (18). Thereby, the High:Low ratio of the comparator output is a pulse width modulation signal, which is amplified (34) for the motor (12), at a much higher frequency than the microprocessor duty cycle.