We show that there is a C∞ open and dense set of positively curved metrics on S2 whose geodesic flow has positive topological entropy, and thus exhibits chaotic behavior. The geodesic flow for each of these metrics possesses a horseshoe and it follows that these metrics have an exponential growth rate of hyperbolic closed geodesics. The positive curvature hypothesis is required to ensure the ex...

it is several decades that the application of membrane processes for gas separation has become a great concern within industries. among them, the polymeric membranes of different structures have played the most important role. such application has been widely extended to gas separation and due to the necessity of both; prediction of the behavior of these processes and recognition of the effecti...

Vertical silos are large cylinders used for material storage in agriculture and mineral industries. One of the silo problems is its obstruction due to dome and dense packing. Depend on the material properties and silo dimensions several techniques are used to solve this problem. In the present work, possibility of obstruction solution of a laboratory silo by ball impact is investigated. Test ma...