“…Combining the power of crowd, the ubiquitously available smart devices, and the high speed Internet, participatory sensor networks have raised more and more attention nowadays [1][2][3]. Participants use their personal smart devices, which have embedded sensors such as camera, microphone, GPS, accelerometer, digital compass, and gyroscope, to gather data and make them available for large-scale applications [4][5][6]. The performance and the efficiency of participatory sensing applications heavily depend on the quality of data contributed by the sensing participants [7,8].…”