Search results for "DF"

H2 hitting on graphene supported palladium cluster: molecular dynamics simulations

2016

Dissociative adsorption of impinging gas-phase molecular hydrogen (H2) on a palladium cluster (Pd4) supported on defective graphene (C47) was studied by periodic density functional theory molecular dynamics simulations. The H2 on Pd4/C47 collision dynamics were investigated without any particular constraint, except for the Born–Oppenheimer approximation. The study, which had mostly method-testing aims, provided, anyway, valuable information about the collision kinetics of gas-phase molecular hydrogen. This was treated as an impacting projectile having different kinetic energy values. At lower kinetic energies, sticking was ruled by steering effects imputable to the Pd cluster that easily re…

Effects of climate, land cover and topography on soil erosion risk in a semiarid basin of the Andes

2016

Understanding soil erosion processes in the Ecuadorian Andes with a tropical wet-dry climate and a variable topography, is fundamental for research on agriculture sustainable, environmental management, as well as for a stable water supply for the local populations. This work proposes method to estimate soil erosion risk in the semiarid Catamayo basin with limited data. The results show that the rainfall distribution and the erosivity along with the rugged topography, followed by the land cover (C-factor), are the most important factors to estimate soil erosion risk. The soil erodibility is the most important factor in the dry season for agricultural areas and where the ground cover is spars…

Vegetation as a tool in the interpretation of fluvial geomorphic processes and landforms

2016

Soil erosion susceptibility assessment and validation using a geostatistical multivariate approach: a test in southern Sicily

2008

A certain number of studies have been carried out in recent years that aim at developing and applying a model capable of assessing water erosion of soil. Some of these have tried to quantitatively evaluate the volumes of soil loss, while others have focused their efforts on the recognition of the areas most prone to water erosion processes. This article presents the results of a research whose objective was that of evaluating water erosion susceptibility in a Sicilian watershed: the Naro river basin. A geomorphological study was carried out to recognize the water erosion landforms and define a set of parameters expressing both the intensity of hydraulic forces and the resistance of rocks/so…

Rainfall energy harvester

2015

This chapter provides a detailed study on the harvest of the energy contained in raindrops by means of piezoelectric transducers. The energy harvester has the role of an electric source, able to recharge storage devices of small electronic components, such wireless sensors, by using the vibrational energy released by the drops hitting the transducer, reducing in such a way the chemical waste of conventional batteries. In technical literature, diverse studies agree on the level of suitable generated voltage on the electrodes of a piezoelectric transducer subjected to rainfall, but a complete characterization on the supplied power is still missing. This work, also to limit optimistic forecast…

STOP 9: Upper Daugava spillway valley and associated gully network at Vasargelišķi

2014

Water erosion susceptibility mapping by applying Stochastic Gradient Treeboost to the Imera Meridionale River Basin (Sicily, Italy)

2016

Abstract Soil erosion by water constitutes a serious problem affecting various countries. In the last few years, a number of studies have adopted statistical approaches for erosion susceptibility zonation. In this study, the Stochastic Gradient Treeboost (SGT) was tested as a multivariate statistical tool for exploring, analyzing and predicting the spatial occurrence of rill–interrill erosion and gully erosion. This technique implements the stochastic gradient boosting algorithm with a tree-based method. The study area is a 9.5 km 2 river catchment located in central-northern Sicily (Italy), where water erosion processes are prevalent, and affect the agricultural productivity of local commu…

1-D numerical simulation of sediment transport in alluvial channel beds: study cases

2011

ABSTRACT Quantitative estimate of sediment transport processes is important especially in river-control engineering and for water management projects. In this paper the sediment routing of a 1-D model is presented and applied to some study cases. The procedure simulates the variations of bed roughness conditions due to natural sorting and to generation and migration of bed forms. The suspended-load and the bed-load are treated separately.

The role of inorganic and organic nutrients on the development of phytoplankton along a transect from the Daugava River mouth to the Open Baltic, in …

2003

Abstract The importance of dissolved silicate (DSi), dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), phosphate and dissolved organic phosphorus (DOP) on algal growth is analysed for the Gulf of Riga and the adjacent open Baltic Sea. The results of three cruises (May, June, and July, 1999) along a transect across the Gulf of Riga from the entrance to the Daugava River to the open Baltic are presented. Nutrient-limitation was identified on the basis of available nutrient concentrations and stoichiometric analysis. In spring, phosphate appeared to be the algal-growth-potential-limiting nutrient at the entrance of the Daugava River, DSi in the central Gulf, and DIN at the …

From Slope Morphometry to Morphogenetic Processes: An Integrated Approach of Field Survey, Geographic Information System Morphometric Analysis and St…

2015

Calanchi (singular: calanco) represent a typical example of badlands in the Italian peninsula, which rapidly evolve on clayey terrains such as the widespread Pliocene–Pleistocene marine clays. The present study aimed at investigating the role of the slope morphometry on the typology and distribution of morphogenetic processes in a calanchi area located in southern Italy. The research included detailed geomorphological surveying as well as morphometric and statistical analyses. The study area was first subdivided into individual hydrographic units (HUs), for which field survey allowed to identify the dominant denudation processes, their intensity and the distribution of the associated landfo…