We consider some typical optimal control problems for a nonlinear model of longitudinal vibrations in a viscoelastic rod. In trying to follow the usual pattern of showing that every innmizing sequence of controls contains a subsequence suitably converging to an optimal control, we confront the severe technical diiculty that the constitutive function cannot be uniformly Lipschitzian in its argum...

We use picosecond x-ray diffuse scattering to image the nonequilibrium vibrations in the lattice following ultrafast laser excitation. We present images of nonequilibrium phonons in InP and InSb throughout the Brillouin zone which remain out of equilibrium up to nanoseconds. The results are analyzed using a Born model that helps identify the phonon branches contributing to the observed features...

The complete phononic band gap (PnBG) of a phononic crystal (PnC) slab is used to efficiently and simultaneously confine both flexural and extensional (longitudinal) elastic vibrations in a resonator. The PnC structure is fabricated by etching a hexagonal (honeycomb) array of air holes in a silicon (Si) slab. Flexural and extensional acoustic modes in the structure are directly excited by a pie...

It is shown that a nanosecond unipolar soliton-like pulse of the type localized shear deformation autowave propagating perpendicular to magnetic field can be formed in cubic paramagnetic crystal subjected longitudinal static direction external field. The influx energy stored ions into due nonequilibrium initial population their stationary quantum states compensated by irreversible losses caused...