Search results for "Flow"

Rill flow velocity and resistance law: A review

2022

Rills caused by runoff concentration on erodible hillslopes generally have very irregular longitudinal profiles and cross-section shapes. Rill erosion directly depends on the hydraulics of flow within the rills which may differ greatly from that in larger and regular channels like streams or rivers. At first, in this paper, a review of the two different approaches to estimate rill flow velocity, based on flow regime and flow resistance laws, is presented. Recent advances in measurements of rill geometry by the three-dimensional photo-reconstruction (3D-PR) technique, which allows one to obtain a Digital Terrain Model (DTM) by low-altitude aerial and terrestrial photogrammetry, are also disc…

A simple field method to measure the hydrodynamic properties of soil surface crust

2013

The hydraulic resistance of the surface crust was determined by a combination of two infiltrometric techniques: first, a surface measurement of steady-state infiltration rate is conducted by a mini-disk tension infiltrometer (MDI); then, the surface crust is removed, its thickness is measured, and a ponded infiltration test is performed at the same site. The Beerkan Estimation of Soil Transfer parameters (BEST) method is applied to estimate the hydraulic properties of the underlying soil provided the particlesize distribution and the bulk density are known. Under the assumption of a unit gradient of hydraulic head below the soil crust, the pressure head at the interface crust-soil is derive…

Modelling flow and heat transfer in spacer-filled membrane distillation channels using open source CFD code

2013

Abstract A good understanding of the details of hydrodynamic and heat transport conditions and their impact on temperature polarisation and pressure drops is essential for optimum design of membrane distillation (MD) modules. To this end, the present work reports on initial progress in the development of a tool for 3D simulation of spacer-filled MD channels based on the open source CFD code library OpenFOAM. The paper discusses a number of modelling and implementation aspects including model geometry and computational domain, choice of boundary conditions, and discretisation schemes. The results pertaining to the effect of three different spacer types on the fluid dynamics and heat transfer…

Editorial: From Meristems to Floral Diversity: Developmental Options and Constraints

2021

L'approche cartographique de la représentation du mouvement spatial. L'exemple des flux commerciaux maritimes euro- méditerranéens

2016

Mapping spatial movement implies to rethink cartographic modelling in addition to digital data issues. This opens research pathways about the representation of spatio-temporal interactions and interrelations. Existing approaches focus either on the map background itself (data analysis issues, to answer thematic questions) or on its “shape”, i.e. on the pure graphical aspects of visualization (edge bundling) and on the semiology rules behind it. This paper aims to further examine the role of the map background in the cartography of maritime flows. This essentially geographic approach differs from existing ones in that it approximates the representation of movement by modelling the mesh of th…

TP53 mutations and S-phase fraction but not DNA-ploidy are independent prognostic indicators in laryngeal squamous cell carcinoma

2005

To prospectively evaluate the prognostic significance of TP53, H-, K-, and N-Ras mutations, DNA-ploidy and S-phase fraction (SPF) in patients affected by locally advanced laryngeal squamous cell carcinoma (LSCC). Eight-one patients (median follow-up was 71 months) who underwent resective surgery for primary operable locally advanced LSCC were analyzed. Tumor DNA was screened for mutational analysis by PCR/SSCP and sequencing. DNA-ploidy and SPF were performed by flow cytometric analyses. Thirty-six patients (44%) had, at least, a mutation in the TP53 gene. Of them, 22% (8/36) had double mutations and 3% (1/36) had triple mutations. In total, 46 TP53 mutations were observed. The majority (41…

High Energy Emission and its Variability in Young Stellar Objects

2019

Young stars show a variety of highly energetic phenomena, from accretion and outflow processes to hot coronal plasmas confined in their outer atmosphere, all regulated by the intense stellar magnetic fields. Many aspects on each of these phenomena are debated, but, most notably, their complex mutual interaction remains obscure. In this work I report how these phenomena are simultaneously responsible for the high-energy emission from young stars, with a special focus on the expected and observed variability in the X-ray band. Investigating variations in the X-ray emission from young stars allows us to pose constraints on flare and coronal plasma properties, coronal heating, accretion stream …

Effect of network pressure on apparent losses due to meters under-registration

2010

The management of migrants' emergency in Sicily (Italy), between suspension of rights and controversies of planning

2015

The attention of the media and international news is addressed to the migration issues, just during the landings of illegal migrants, and especially when these landings are linked to the deaths of migrants. However, for nearly thirty years, Sicily, among the Southern European regions most affected by the phenomenon of migration flows, has assumed the role of “gate” which introduces to Europe from Africa, making a bridge among nearest worlds, but often extremely different. This condition is, in fact, a historical value, given that Sicily has always been the crossroads of migration flows among Mediterranean Europe, Asia and Africa which allowed the exchange among cultures, ethnicities and rel…

A regional GIS-based model for reconstructing natural monthly streamflow series at ungauged sites

2016

Several hydrologic applications require reliable estimates of monthly runoff in river basins to face the widespread lack of data, both in time and in space. The main aim of this work is to propose a regional model for the estimation of monthly natural runoff series at ungauged sites, analyzing its applicability, reliability and limitations. A GIS (Geographic Information System) based model is here developed and applied to the entire region of Sicily (Italy). The core of this tool is a regional model for the estimation of monthly natural runoff series, based on a simple modelling structure, consisting of a regression based rainfall-runoff model with only four parameters. The monthly runoff i…