中文摘要：

Najam Nazar received his BS degree in computer science from University of the Punjab, Lahore, Pakistan in 2005 and MS degree in Software Engineering from Chalmers University of Technology, Swe- den in 2010. He is currently working to- wards his PhD degree in software engi- neering at Dalian University of Technol-ogy, China. His current research interest includes mining software repositories, data mining, natural language processing, machine learning, software product lines, and agile methodologies. E-mail： jianghe@dlut.edu.cn,He Jiang received the PhD degree in com- puter science from the University of Sci- ence and Technology of China, China. He is currently a professor in Dalian Univer- sity of Technology, China. His current re- search interests include computational in- telligence and its applications in software engineering and data mining. He is also a member of the ACM and the CCF. Guojun Gao received his Bachelor＇s De- gree in software engineering from School of Software, Dalian University of Technol- ogy, China in 2014. Currently, he is pur- suing MS degree in software engineering from the same university. His research in- terests include the defects prediction, de- tection in software engineering. Tao Zhang received the BE, ME degrees in automation and software engineering from Northeastern University, China in 2005 and 2008, respectively. He received the PhD de- gree in computer science from University of Seoul, South Korea in 2013. He was a re- search professor at the University of Seoul, South Korea from 2013 to 2014. Currently,he is a postdoctoral fellow at the Hong Kong Polytechnic University, China. His research interest includes mining software maintenance, security and privacy for mobile apps, and recommendation systems. Xiaochen Li received the BS degree in soft- ware engineering from the Dalian Univer- sity of Technology, China in 2015. He is currently a PhD candidate in Dalian Uni- versity of Technology. His current research interest is mining software repositories in software engineer