Here friend. The explanation for ambient occlusion http://www.geforce.com/whats-new/guides/ambient-occlusion#1. And for triple buffering In computer graphics, triple buffering is similar to double buffering but provides a speed improvement. In double buffering the program must wait until the finished drawing is copied or swapped before starting the next drawing. This waiting period could be several milliseconds during which neither buffer can be touched.
In triple buffering the program has two back buffers and can immediately start drawing in the one that is not involved in such copying. The third buffer, the front buffer, is read by the graphics card to display the image on the monitor. More information here http://www.tweakguides.com/Graphics_10.html.
Hope it helped