Resilience Capital Partners, a private equity firm that invests in middle-market companies, announced it has acquired Concord, California-headquartered Systron Donner Inertial. As the world's leading supplier of quartz microelectromechanical systems (QMEMS) used in inertial sensing products that provide precision guidance, navigation and locational solutions, Systron Donner develops products that have been used in everything from business aircraft to fighter jets to the MARS Rover.