Three distinct but brief signals from the Indian Ocean revived hope for investigators in the search for missing Malaysia Airlines Flight 370 on Sunday, as authorities rush to determine the origin of the signals before the batteries of the plane’s black box run out. Australian authorities confirmed on Sunday that a Chinese patrol vessel, the Haixun 01, had picked up a fleeting “ping” signal twice on Friday and Saturday in waters west of Perth, near where investigators believe Malaysia Airlines Flight MH370 went down on March 8. As a consequence, more planes and ships were being sent to assist in that area. Meanwhile, on Sunday, an Australian ship carrying sophisticated deep-sea sound equipment picked up a third signal in a different part of the massive search area, some 300 nautical miles away. More