An apparatus and method to measure, establish and implement a desired range of travel allowed a reclining seat back portion of an airline seating accommodation. The associative memory is a small-area associative memory formed using CMOS technology with a fast parallel minimum-distance-search capability. Both a hardness of the core outer surface and a hardness within the outermost transition volume are less than the hardness of the geometric center to define a negative hardness gradient. The system can be programmed to operate automatically under computer control such that reversal of the flow through the geothermal system does not shock or damage the equipment or buried piping. White-based power conservation as described herein may be performed while a person uses the electronics device, which reduces power consumption continually during usage. The emulsion is useful in formulating personal care products.