42 Technical consultation in the field of engineering; analysis, research, design engineering, and product development for others in the field of free-piston machines, free piston machines coupled with other machines, stirling heat engines, mechanical cooling and cryocooling devices, linear compressors, biomass fired electric generators, solar and wind conversion apparatus, fuel-fired compressors coupled to and driven by stirling engines, free-piston stirling coolers driven by free-piston stirling engines, turbines driven by free-piston stirling engine, burners for external combustion engines; linear motors; and linear alternators