Underwater acoustic communications constitute a very difficult issue since the transmission channel is severely doubly dispersive. Indeed, radio waves suffer from strong attenuation so that the only solution is to use acoustical modems. Thus, achievable bandpass is very reduced (typically less than 20kHz) and narrowband signal approximation cannot be assumed since sound velocity is around 1500 ...

The use of Catechin as an antibacterial agent is becoming ever-more common, whereas unstable and easy oxidation, have limited its application. A simple and low-energy-consuming approach to synthesize highly stable and dispersive Catechin-Cu nanoparticles(NPs) has been developed, in which the stability and dispersivity of the NPs are varied greatly with the pH value and temperature of the reacti...

A two-well forced-gradient experiment involving virus and microsphere transport was carried out in a sandy aquifer in Borden, Ontario, Canada. Virus traveled at least a few meters in the experiment, but virus concentrations at observation points 1 and 2.54 m away from the injection well were a small fraction of those injected. A simplified planar radial advection-dispersion equation with consta...

Dispersion in porous media has been postulated as a mechanism that can increase particle transport, but the magnitude of increased transport predicted using analytical models of column experiments is a function of the boundary conditions chosen for the models. To date, insufficient attention has been paid to the implications of these boundary conditions for column or field simulations of partic...

In modeling transport within naturally heterogeneous aquifers, it is usually assumed that the transport equations valid at local scales can also be applied at larger scales. At larger scales, the heterogeneous domain is represented by an equivalent homogeneous medium. Convergent-flow tracer tests constitute one of the most frequently used field tests to estimate effective input parameters of eq...

Effective use of colloid transport models for heterogeneous subsurface porous media requires the development of methodologies to identify the key model parameters. The inverse problem of a two-dimensional model for colloid transport in geochemically heterogeneous porous media is systematically investigated in this paper. Sensitivity analysis prior to the parameter identification provided valuab...

We study mixing and spreading in a very simple heterogeneous system: a numerical flow cell comprised of two homogeneous porous media separated by a sharp angled interface. The two media have identical porosity, but differing permeability and dispersivity characteristics representing a fine and a coarse medium. We focus on transport in advection-dominated systems as the primary role of the angle...

Abstract Dynamic hydrologic exchange flows in river beds and banks are important for many ecosystem functions throughout corridors. Here we test whether the exchanges associated mixing between a flooding groundwater within river’s bank can be effectively traced by Radon‐222 ( 222 Rn), naturally occurring, inert, radiogenic, radioactive gas that analyzed monitored situ. The assessment was done s...

In this study, we synthesized core/shell structures comprising monodisperse 3-μm SiO(2) microspheres and gold nanoparticles (AuNPs, ca. 6.7 nm) as the core and shell components, respectively. Using a layer-by-layer cross-linking process with a dithiol cross-linking agent, we prepared low-permittivity AuNP-encapsulated high-permittivity SiO(2) core/shell microspheres with variable AuNP shell thi...