The geomorphic behavior of a soil-mantled hillslope undergoing diffusive creep involves a coupling between changes in land surface elevation, soil transport rates, soil production, and soil thickness. A linear stability analysis suggests that the coupled response of the soil mantle to small perturbations in soil thickness or surface topography is influenced by two factors. The diffusive-like be...

The response to perturbations of a simplified transport model is studied. The model is used as a paradigmatic example of transport controlled by a critical gradient. Long-time system behaviour is diffusive when most of the system is sub-critical. However, when the critical mechanism becomes significant, it is observed to dominate the system behaviour at both short and long time scales. While th...

We study by direct numerical simulations the effects of Schmidt number ~Sc! on passive scalars mixed by forced isotropic and homogeneous turbulence. The scalar field is maintained statistically stationary by a uniform mean gradient. We consider the scaling of spectra, structure functions, local isotropy and intermittency. For moderately diffusive scalars with Sc51/8 and 1, the Taylor-scale Reyn...

The diffusive (or semiconvection) regime of double-diffusive convection (DDC) is widespread in the polar oceans, generating ‘‘staircases’’ consisting of high-gradient interfaces of temperature and salinity separated by convectively mixed layers. Using two-dimensional direct numerical simulations, support is provided for a previous theory that rotation can influence DDC heat fluxes when the thic...

We investigate the time evolution of a model system of interacting particles moving in a d-dimensional torus. The microscopic dynamics is first order in time with velocities set equal to the negative gradient of a potential energy term 9 plus independent Brownian motions: 9 is the sum of pair potentials, V(r)+#J(#r); the second term has the form of a Kac potential with inverse range #. Using di...

The objective of this study was to develop a method for measuring the mobility of persistent organic pollutants in the solid phase of soils within the context of environmental pollution risk assessment. A new diffusive probe, purposely designed by adapting the diffusive gradient technique method, measures labile organic species by immobilizing them after diffusion through a thin deionized water...

although there are many methods for image denoising, but partial differential equation (pde) based denoising attracted much attention in the field of medical image processing such as magnetic resonance imaging (mri). the main advantage of pde-based denoising approach is laid in its ability to smooth image in a nonlinear way, which effectively removes the noise, as well as preserving edge throug...