Abstract: The present invention relates to pulse jet engines. More specifically, the present invention concerns a pulse jet engine which uses fluidic valving rather than unreliable mechanical valves, incorporates two combustion chambers with approximately the same but approximately 180 degree out-of-phase resonance frequencies to reduce noise through destructive interference of sound waves, and controls fuel injection and ignition within the two combustion chambers to increase efficiency by achieving more rapid and complete combustion.

Abstract: A system and method for reducing interaction between surfaces (10,12) moving relative to each other. The system includes a first surface (10) having a first number of repetitive surface-asperities (14), e.g., 11, per unit length of surface, and a second surface (12) having a second number of repetitive surface asperities (16), e.g., 13, per unit length of surface, with the first and second numbers being in relative prime ratio, i.e., having no common divisor other than 1. The ratio of repetitive surface asperities may be controlled as a function of component particle size, grain size; groove size; or relative angular orientation of the surfaces (110,112).