Jiang Hanpeng (3rd R) and Lei Qingyang (2nd R), both from Middle School Attached to Northern Jiaotong University, demonstrate Quad Motor Helicopter Tracking System on the 41st International Exhibition of Inventions of Geneva, in Palexpo of Geneva, Switzerland, April 10, 2013. Some 50 Chinese participants came to the exhibition to display their 23 objects of invention. (Xinhua/Wang Siwei)