The non-Markovian nature of polymer motions is accounted for in folding kinetics, using frequencydependent friction. Folding, like many other problems in the physics of disordered systems, involves barrier crossing on a correlated energy landscape. A variational transition state theory that reduces to the usual Bryngelson-Wolynes Kramers approach when the non-Markovian aspects are neglected is ...

We calculate the van der Waals friction between two semi-infinite solids in normal relative motion and find a drastic difference in comparison with the parallel relative motion. The case of good conductors is investigated in detail both within the local optic approximation and using a nonlocal optic dielectric approach. We show that the friction may increase by many orders of magnitude when the...

Flat plate skin friction calculations over a range of Mach numbers from 0.4 to 3.5 at Reynolds numbers from 16 million to 492 million using a Navier Stokes method with advanced turbulence modeling are compared with incompressible skin friction coefficient correlations. The semi-empirical correlation theories of van Driest; Cope; Winkler and Cha; and Sommer and Short T’ are used to transform the...

Internally Architectured Materials (IAMs) that exhibit different friction forces for sliding in the opposite directions are proposed. This is achieved by translating deformation normal to the sliding plane into a tangential force in a manner that is akin to a toothbrush with inclined bristles. Friction asymmetry is attained by employing a layered material or a structure with parallel 'ribs' inc...

In ultra-precision positioning equipment, the accuracy is affected by friction characteristics, especially pre-slip stage. At present, research on mainly includes contact theory and dynamic process. There no time variable in models, so they only apply to stage of static contact, while establishment a dynamics model depends parameter identification cannot reflect influence rough morphology load....