The rainbow is due to extrema of the angular deflection function of light impinging on water drops. Generically, extrema of suitably defined deflection functions lead to rainbows. These include angular and rotational rainbows in surface scattering and more. Here we introduce the concept of an "energy-loss deflection function" for scattering of particles from a periodic surface whose extrema lea...

Waste fibers produced from manufacturing processes are a byproduct commonly deposited in storing yards and/or landfills and thus results in many serious environmental problems in Iran. If these waste materials could be advantageously put to practical use in any application, it would reduce the burden on the environment and landfills. This paper compares the performance of the stone matrix aspha...

ribology is the science and technology of contacting solid surfaces in relative motion, including the study of lubricants, lubrication, friction, wear, and bearings. It is estimated that friction and wear cost the U.S. economy 6% of the gross national product [1]. For example, 5% of the total energy generated in an automobile engine is lost to frictional resistance. The study of nanoscale frict...

The performance of a wide variety of ultra-sensitive devices employing nanoelectromechanical resonators is determined by their mechanical quality factor, yet energy dissipation in these systems remains poorly understood. Here we develop a comprehensive theory of friction in high frequency resonators caused by the radiation of elastic energy into the support substrate, referred to as clamping lo...

Triacetone triperoxide (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexoxonane; TATP) is one of the most frequently used improvised explosives, often misused worldwide. In our previous studies, we had observed that the kind of acid used to catalyse its formation has a significant influence on TATP’s properties. TATP was prepared using five different acids that are often used in improvised conditions. Al...

Recent developments in nanostructured products draw considerable attention to ultrafine grained materials. These materials are normally manufactured by different severe plastic deformation (SPD) methods. In the present study, analytical models and finite element method (FEM) are used to calculate strain imposed to a specimen that was deformed by equal channel angular pressing (ECAP). In additio...

In this study electrical discharge process was used to increase surface wear resistance of pure aluminum. Pulse-on-time and pulse current were considered as input parameters of the electrical discharge process. Experimental results reveal that the electrical discharge process is a successful method for improving the surface wear resistance of aluminum, so that this method has greatly increased ...

This computational fluid dynamic analysis attempts to simulate the incompressible steady fluid flow and heat transfer in a solar air channel with wall-mounted baffles. Two ꞌSꞌ-shaped baffles, having different orientations, i.e., ꞌSꞌ-upstream and ꞌSꞌ-downstream, were inserted into the channel and fixed to the top and bottom walls of the channel in a periodically staggered manner to develop vorti...