Engineers at the University of Florida, Gainesville, have built a machine that can crank out Hurricane Katrina-like conditions to test the sturdiness of structures and materials. The trailer-mounted apparatus sports eight five-foot fans powered by four 700-horsepower marine engines. A duct and rudders allow precise control of wind speed and direction; a water-injection system simulates wind-driven rain. Forrest Masters, a civil engineer at the university and a leader of the hurricane-simulator project, plans to use the machine to blast state-donated homes, building products, and trees. The data will be used to help Florida update its statewide building codes.