Thank you very much for your replies, RICe have an very good offer when they confirm to me three year of financial support.
the field I prefer to work on is dynamics and control field ( focus on Robotics). During my application process, I have some contacts with professor in the RPI, and professor help me to admit and also provide me financial support for it. Professor assigned me to work on some interesting projects however just one year financial support confirmed. At RIce, I did not have any contact with professors, They just assigned for me 2 temporary professors work on one field. My professors are not working on robotics field. They work on theoretical control theories, chaotic theories and Nanotech.
RIce graduate mechanical engineering school is very small, I wish to receive some advices on which is the advantage of a big department like RPI or small department like RICE.