Search results for "Deposition process"

Locally Frozen Defects in Random Sequential Adsorption with Diffusional Relaxation

1993

Random sequential adsorption with diffusional relaxation, of two by two square objects on the two-dimensional square lattice is studied by Monte Carlo computer simulation. Asymptotically for large lattice sizes, diffusional relaxation allows the deposition process to reach full coverage. The coverage approaches the full occupation value, 1, as a power-law with convergence exponent near 1/2. For a periodic lattice of finite (even) size $L$, the final state is a frozen random rectangular grid of domain walls connecting single-site defects. The domain sizes saturate at L**0.8. Prior to saturation, i.e., asymptotically for infinite lattice, the domain growth is power-law with growth exponent ne…

Quality assessment of protein NMR structures.

2013

Biomolecular NMR structures are now routinely used in biology, chemistry, and bioinformatics. Methods and metrics for assessing the accuracy and precision of protein NMR structures are beginning to be standardized across the biological NMR community. These include both knowledge-based assessment metrics, parameterized from the database of protein structures, and model versus data assessment metrics. On line servers are available that provide comprehensive protein structure quality assessment reports, and efforts are in progress by the world-wide Protein Data Bank (wwPDB) to develop a biomolecular NMR structure quality assessment pipeline as part of the structure deposition process. These qu…

Experimental data collection and modelling of dry deposition velocities for urban surfaces

2018

Dry deposition process is recognized as an important pathway among the removal processes of radioactive pollutants in atmosphere. There is not a unique and accepted theoretical description of involved dry deposition phenomena due to the complexity of the fluid-dynamic processes that influence the deposition flux, but also because there is a lack of experimental data covering all scenarios of interest. In this paper, that is the result of a National Research Program a research activity conducted by DEIM Department of the University of Palermo and ENEA and funded by the Italian Minister of Economic Development, a new schema for parameterization of particle dry deposition velocity on urban are…

Atmospheric dry deposition processes of particles on urban and suburban surfaces: Modelling and validation works

2019

Abstract Dry deposition process is one of the important pathways for the removal of particles from atmosphere. It is the result of a combination of different environmental and physical factors as atmospheric conditions, particle properties, characteristics of the canopy. For this latter factor, urban canopy represents unevenly combinations of different types of surface elements that increases the complexity of deposition process phenomena. Therefore, particle dry deposition on urban surfaces is not easy to configure and, although empirical or semi-empirical models in literature have been developed to address this aspect, there is not standardized and commonly accepted criteria, especially f…

Aeolian Remobilisation of the 2011-Cordón Caulle Tephra-Fallout Deposit: Example of an Important Process in the Life Cycle of Volcanic Ash

2020

Collective Effects in Random Sequential Adsorption of Diffusing Hard Squares

1992

We study by Monte Carlo computer simulations random sequential adsorption (RSA) with diffusional relaxation, of lattice hard squares in two dimensions. While for RSA without diffusion the coverage approaches its maximum jamming value (large-time fractional coverage) exponentially, added diffusion allows the deposition process to proceed to the full coverage. The approach to the full coverage is consistent with the t**(-1/2) power law reminiscent of the equilibrium cluster coarsening in models with nonconserved order-parameter dynamics.

Aeolian Remobilisation of the 2011-Cordón Caulle Tephra-Fallout Deposit: Example of an Important Process in the Life Cycle of Volcanic Ash

2020

Although volcanic eruptions represent short periods in the whole history of a volcano, the large amount of loose pyroclastic material produced, combined with aeolian processes, can lead to continuous, long-lasting reworking of volcanic products. Driven by wind, these processes significantly influence the geomorphology and prolong the impacts of eruptions on exposed communities and ecosystems. Since such phenomena are of interest to scientists from a range of disciplines (e.g., volcanology, atmospheric and soil sciences), a well-defined, common nomenclature is necessary to optimise the multidisciplinary characterisation of both processes and deposits. We, therefore, first describe ash wind-r…