During the last decade, others have extended the nanofactory concept, including an analysis of nanofactory convergent assembly by Ralph Merkle, a systems design of a replicating nanofactory architecture by J . Storrs Hall, Forrest Bishop's " Universal Assembler ", the patented exponential assembly process by Zyvex, and a top-level systems design for a'primitive nanofactory'by Chris Phoenix ( Director of Research at the Center for Responsible Nanotechnology ).