As many Americans despair over disappearing factory jobs and fear being replaced by a machine, Natan Linder has set out to arm assembly-line workers with cutting-edge technology and help preserve the U.S. manufacturing market. He's launched Tulip, an app that connects every element of a production line to a data collection program where it can be analyzed so crews can smarten and streamline their operation. New Balance and Merck have signed on. A byproduct, Linder hopes, is attracting a qualified younger generation to help fill 3.5 million jobs the Manufacturing Institute, a Washington-based think tank, has predicted will become available over the next decade. Linder, who arrived at the Massachusetts Institute of Technology's Media Lab from Israel in 2008, cofounded 3D printing company Formlabs in Somerville before launching Tulip, the result of almost a decade of research.