The paper deal with two key problems for delta (or singular) shock solutions to systems of conservation laws: entropy admissibility conditions for them (which is connected to the notorious uniqueness problem) and their interaction. A way we chose is to represent them by nets of piecewise constant (or constant with respect only to the space variable) functions, here called shadow waves. All the ...

We study the evolution of the universe which contains a multiple number of nonrelativistic scalar fields decaying into both radiation and pressureless matter. We present a powerful analytic formalism to calculate the matter and radiation curvature perturbations, and find that our analytic estimates agree with full numerical results within an error of less than one percent. Also we discuss the i...

A closed universe containing pressureless dust, more generally perfect fluid matter with pressure-to-density ratio w in the range ( 3 ,− 3 ), violates holographic principle applied according to the Fischler-Susskind proposal. We show, first for a class of two-fluid solutions and then for the general multifluid case, that the closed universe will obey the holographic principle if it also contain...

The application of an electric field over a ceramic powder compact at elevated temperatures gives rise to “flash sintering”. phenomenon occurs critical combination and temperature, which leads rapid increase in the power dissipated within sample. This results sample densification far shorter timescales than those required with conventional sintering. paper reports first successful pressureless ...

We establish the equivalence of free piston and delta shock, for one-space-dimensional pressureless compressible Euler equations. The shock appearing in singular Riemann problem is exactly that may move freely forward or backward a straight tube, driven by flows on two sides it tube. This result not only helps to understand physics somewhat mysterious shocks, but also provides way reduce fluid-...

flood spreading stations were constructed in iran with different objectives such as groundwater recharge and vegetation recovery. accumulation of sediment can be a major problem in flood spreading stations. according to generally accepted theories, floods and salt pollution can reduce gradually the infiltration rate. in order to investigate this issue, 13 flood spreading stations were selected ...

lymphocytic infiltration of jessner-kanof is a chronic, benign t cell infiltration disorder of exposed skin with unknown etiology. in some instances, these lesions are induced or aggravated by light exposure. in this case report, we are going to describe an interesting occupationally related skin disease, jessner's disease, after several years working with computer. on the basis of literature r...