I basically applied for a PhD in systems engineering in Boston University and many other universities. The department of Systems Engineering at BU was extremely fast, responsive and supportive. Two months later I was invited for an open house graduation. They booked my flight and hotel. I attended a three day graduate open house. It started with a dinner in a Japanese restaurant with a small group of friendly professors, the program director and other candidates. The day after we took a tour to see different labs and also we had 1:1 interviews with some potential advisers of our choice.

Individual faculty interviews with principal investigators where they ask you questions based on your experience and their own background. They try to match based on which program you want to join. Current students facilitate getting you to and from each interview.