Search results for " Flow"

Respiratory support in patients with severe COVID-19 in the International Severe Acute Respiratory and Emerging Infection (ISARIC) COVID-19 study: a …

2022

Invasive mechanical ventilation; COVID-19; Critical care Ventilación mecánica invasiva; COVID-19; Cuidado crítico Ventilació mecànica invasiva; COVID-19; Atenció crítica Background Up to 30% of hospitalised patients with COVID-19 require advanced respiratory support, including high-flow nasal cannulas (HFNC), non-invasive mechanical ventilation (NIV), or invasive mechanical ventilation (IMV). We aimed to describe the clinical characteristics, outcomes and risk factors for failing non-invasive respiratory support in patients treated with severe COVID-19 during the first two years of the pandemic in high-income countries (HICs) and low middle-income countries (LMICs). Methods This is a multin…

MAST-RT0 SOLUTION OF 3D NAVIER STOKES EQUATIONS ON UNSTRUCTURED MESHS. PRELIMINARY RESULTS IN THE LAMINAR CASE

2021

MAST-RT0 solution of 3D Navier Stokes equations in very irregular domains. Preliminary results in the laminar case

2021

A new numerical methodology to solve the 3D Navier-Stokes equations for incompressible fluids within complex boundaries and unstructured body-fitted tetrahedral mesh is presented and validated with three literature and one real-case tests. We apply a fractional time step procedure where a predictor and a corrector problem are sequentially solved. The predictor step is solved applying the MAST (Marching in Space and Time) procedure, which explicitly handles the non-linear terms in the momentum equations, allowing numerical stability for Courant number greater than one. Correction steps are solved by a Mixed Hybrid Finite Elements discretization that assumes positive distances among tetrahedr…

Genetic structure in the paleoendemic and endangered Petagnaea gussonei (Spreng.) Rauschert (Saniculoideae, Apiaceae) and implications for its conser…

2012

Our investigation aims to understand the genetic structure and evolutionary history of Petagnaea gussonei, an ancient and endangered species belonging to the Saniculoideae subfamily (Apiaceae). It is paleoendemic to Sicily, with a small number of populations in the Nebrodi Mountains. A total of seven chloroplast microsatellite repeat loci and 12 AFLP primer combinations were used to screen 115 individuals corresponding to 17 populations. The ratio of seed to pollen flow was also calculated using the modified Ennos equation. A relatively high level of genetic diversity was detected with AFLPs (e.g., 0.045 < H < 0.278), and a moderate variation was also found using cpSSRs (0 < Hk < 0.667). Tw…

An alternative conception of PM10 concentration changes after short-term precipitation in urban environment

2018

Abstract In the article, a linear model is presented which describes a reduction of PM10 mass concentration in relation to the type of precipitation and water vapour content in the air. The model was built using covariance analysis. In studies of PM10 concentration changes, the results of 247 observations were used, which were carried out in the urban area. Concentration changes were archived during short-term (30 min) convection and large-scale rainfalls. For the determination of PM10 mass concentration, the reference method was used. To describe changes in PM10 concentration in the air after precipitation, a series of linear models were created, in which the explanatory variables were: th…

Landfill gas upgrading with pilot-scale water scrubber: Performance assessment with absorption water recycling

2012

Abstract A pilot-scale counter current absorption process for upgrading municipal solid waste (MSW) landfill gas to produce vehicle fuel was studied using absorption, desorption and drying units and water as an absorbent. Continuous water recycling was used without adding new water to the system. The process parameters were defined by a previous study made with this pilot system. The effect of pressure (20–25 bar), temperature (10–25 °C) and water flow speed (5.5–11 l/min) on the upgrading performance, trace compounds (siloxanes, halogenated compounds) and water quality were investigated. Raw landfill gas flow was kept constant at 7.41 Nm3/h. Methane (CH4) and carbon dioxide (CO2) contents …

An experimental investigation on ionic shortcut currents reduction in Acid-Base Flow Battery systems

2022

A Bi-objective Optimization Study of an Acid-Base Flow Battery for High Efficiency and Improved Power Density

2022

Electrical energy storage is critical for a broader penetration of renewable energies with intermittent nature, such as solar and wind energy. The Acid/Base Flow Battery (AB-FB) is a unique, sustainable, and environmental-friendly storage technology with high electrolyte solution energy density. The method relies on reversible electrodialytic technologies using bipolar membranes to transform electrical energy into chemical energy related to pH gradients and vice versa. The charge phase is accomplished by using bipolar membrane electrodialysis, whereas the discharge phase is performed via bipolar membrane reverse electrodialysis. In a previous work, we developed an advanced multi-scale proce…

Acoustic doppler velocity profiler for velocity and turbulence measurements in a large amplitude meandering flume

2008

Flow over deformed bed of a meandering laboratory channel is experimentally investigated. The velocity components have been obtained using an Ultrasonic Doppler Profiler (DOP2000) that measures the instantaneous flow velocity profile along the probe direction. In this work, some results obtained in peculiar sections along the channel are reported. A refined mesh of the measurement points has been used for each considered cross-section. The analysis of the collected data essentially confirms that when the aspect ratio is small the secondary circulation assumes great importance and, in accordance with previous findings, a second counter-rotating secondary circulation cell appears near the fre…

Transpiration and Water Use of an Irrigated Traditional Olive Grove with Sap-Flow Observations and the FAO56 Dual Crop Coefficient Approach

2021

The SIMDualKc model was applied to evaluate the crop water use and the crop coefficient (Kc) of an irrigated olive grove (Olea europaea L.) located in Sicily, Italy, using experimental data collected from two crop seasons. The model applies the FAO56 dual Kc approach to compute the actual crop evapotranspiration (ETc act) and its components, i.e., the actual tree transpiration (Tc act), obtained through the basal crop coefficient (Kcb), and soil evaporation according to an evaporation coefficient (Ke). Model calibration was performed by minimizing the difference between the predicted Tc act and the observed daily tree transpiration measured with sap flow instrumentation (TSF field) acquired…