inverse problem is one of the most important problems in geophysics as model parameters can be estimated from the measured data directly using inverse techniques. in this paper, applying different inverse methods on integration of s-wave and gpr velocities are investigated for estimation of porosity and water saturation. a combination of linear and nonlinear inverse problems are solved. linear ...

We have measured the radon di!usion, solubility and permeability coe$cients of various foils being of interest for the Borexino experiment. The applied methods and instrumentation are described and the mathematical model for di!usion of Rn, including its decay, is outlined. A very strong in#uence of water on the Rn di!usion through nylon foils was found. The rather low Rn permeability for dry n...

The prior estimate and decay property of positive solutions are derived for a system of quasilinear elliptic 9 di$erential equations 3rst. Then, the nonexistence result for radially nonincreasing positive solutions of the system is implied. By using this nonexistence result, blow-up estimates for a class of quasilinear reaction–di$usion 11 systems (non-Newtonian 3ltration systems) are establish...

We compared the behavior of the Hodgkin}Huxley (HH) model subjected to two input regimes: "rstly, discrete pulses from a Poisson process, and then to a di!usion approximation, constructed to share statistical properties with the discrete pulse input. The results show that under a wide range of physiologically plausible input conditions the di!usion process is equivalent to the pulse process, in...

Metastable dynamics, which qualitatively refers to physical processes that involve an extremely slow approach to their nal equilibrium states, is often associated with singularly perturbed convection-di usion-reaction equations. A problem exhibits metastable behavior when the approach to equilibrium occurs on a time-scale of order O(eC" ), where C > 0 and " is the singular perturbation paramete...

The di usion orientation distribution function (ODF) can be reconstructed from q-ball imaging (QBI) to map the complex intravoxel structure of water di usion. As acquisition time is particularly large for high angular resolution di usion imaging (HARDI), fast estimation algorithms have recently been proposed, as an on-line feedback on the reconstruction accuracy. Thus the acquisition could be s...

In the present paper we consider the transition semigroup Pt related to some stochastic reaction-di€usion equations with the nonlinear term f having polynomial growth and satisfying some dissipativity conditions. We are proving that it has a regularizing e€ect in the Banach space of continuous functions C…O†, where O R is a bounded open set. In L2…O† the only result proved is the strong Feller ...

We simulate and analyze the behavior of stationary and moving spatially periodic patterns in a simple cross-#ow reactor with a "rst-order exothermic reactor and realistically high Pe and ̧e. Novel nonTuring stationary patterns emerge due to reactor}di!usion}convection interaction in the simple model that incorporates only concentration and temperature as its variables. We extend our previous an...

Phytoplankton requires light for photosynthesis, but most phytoplankton species are heavier than water and sink. How can these sinking species persist? Here we show, by means of an advection-di usion-reaction equation of light-limited phytoplankton, that the answer lies in the turbulent motion of water that re-disperses phytoplankton over the vertical water column. More speci cally, we show tha...

when a direct voltage is applied under low injection conditions. In Equation (1) o is the angular frequency o= 2pf, where f is the frequency, R0=(dI/ dV)ÿ1, tp is the lifetime of the hole minority carriers, w is the length of the lower doped n bulk region, Lp is the minority carrier di€usion length for holes, with tp=Lp /Dp, where Dp is the di€usion coecient, and ®nally tw=w /Dp is a character...