About a 'Dual-double helix'Mode and Evolution Mechanism of Engineering

In this essay,the process of evolution of engineering is taked as dual-double helix mode,which is made of technology chain and non-technology chain(economic-social chain).The process includes three steps(invention,innovation and diffusion).The dual-double helix evolution of technology chain means the hardware(machine) evolution and software(knowledge and institution) evolution.One important mechanism of engineering evolution is choosing and construction.Through the choosing mechanism,the good results of technology invention come into market and promote the evolution of engineering and marketing activities.Through construction mechanism,technology chain and economic-social chain transform new style.