Search results for "Concentration."

CFD modelling of profiled membranes channels for reverse electrodialysis

2014

Reverse electrodialysis (RE) is a promising technology for electric power generation from controlled mixing of two differently concentrated salt solutions, where ion-exchange membranes are adopted for the generation of ionic currents within the system. Channel geometry strongly influences fluid flow and thus crucial phenomena such as pressure drop and concentration polarization. Profiled membranes are an alternative to the more commonly adopted net spacers and offer a number of advantages: avoiding the use of non-conductive and relatively expensive materials, reducing hydraulic losses and increasing the active membrane area. In this work, Computational Fluid Dynamic simulations were perform…

Computational Fluid Dynamics of Reverse Electrodialysis Systems

CFD simulation of Electrodialysis channels equipped with profiled membranes

Electrodialysis (ED) is a membrane-based electrochemical process that remove ions from a solution. The main use of ED is for the production of drinking water by brackish water desalination, but there are several other applications. ED is characterized by the coexistence and the interaction of different physical phenomena that affect the stack performance. Among them, fluid dynamics and mass transport are crucial: concentration polarization affects the limiting current density and the non-Ohmic voltage drop due to the chemical potential difference between the two solutions; pressure drop affects the pumping power consumption. Moreover, the total energy consumption depends also on the Ohmic v…

Flow and mass transfer in spacer-filled channels for reverse electrodialysis: a CFD parametrical study

2016

Abstract In reverse electrodialysis (RED) concentration polarization phenomena and pressure drop affect strongly the power output obtainable; therefore the channel geometry has a crucial impact on the system optimization. Both overlapped and woven spacers are commonly commercialised and adopted for RED experiments; the latter exhibit some potential advantages, such as better mixing and lower shadow effect, but they have been poorly investigated in the literature so far. In this work, computational fluid dynamics was used to predict fluid flow and mass transfer in spacer-filled channels for RED applications. A parametric analysis for different spacer geometries was carried out: woven (w) and…

CFD prediction of scalar transport in thin channels for reverse electrodialysis

2014

Reverse ElectroDialysis (RED) is a very promising technology allowing the electrochemical potential difference of a salinity gradient to be directly converted into electric energy. The fluid dynamics optimization of the thin channels used in RED is still an open problem. The present preliminary work focuses on the Computational Fluid Dynamics (CFD) simulation of the flow and concentration fields in these channels. In particular three different configurations were investigated: a channel unprovided with a spacer (empty channel) and two channels filled with spacers, one made of overlapped filaments the other of woven filaments. The transport of two passive scalars, representative of the ions …

A Novel Expert System for Non-Invasive Liver Iron Overload Estimation in Thalassemic Patients

2014

Expert Systems can integrate logic based often on computational intelligence methods and they are used in complex problem solving. In this work an Expert System for classifying liver iron concentration in thalassemic patients is presented. In this work, an ANN is used to validate the output of the L.I.O.MO.T (Liver Iron Overload Monitoring in Thalassemia) method against the output of the state-of-the-art method based on MRI T2 assessment for liver iron concentration. The model has been validated with a dataset of 200 samples. The experimental Mean Squared Error results and Correlation show interesting performances. The proposed algorithm has been developed as a plug in for OsiriX Dicom View…

Gli spettri, il conforto della letteratura e l’autenticità del reale nell’esperienza concentrazionaria di Charlotte Delbo

2020

The Holocaust literature transforms many narrative categories in an attempt to find forms capable of conveying the historical experience of extermination. As an alternative to the impossible mimetic reproduction of reality, many authors resort to the imaginary and its rhetorical and narrative devices to reconstruct the concentrationary experience. The essay aims to trace the forms and functions of phantasmagoria in some texts by Charlotte Delbo where the transfiguration of reality makes the process of remembrance possible and, at the same time, the recomposition of the subject.

Helicobacter pylori and Barrett’s esophagus: a protective factor or a real cause?

2017

Nothwithstanding the definite aethiopathogenetic path of certain diseases, the relationship between Helicobacter Pylori (H. Pylori) and barrett's esophagus (BE), a condition that increases the risk for dysplasia and consequently adenocarcinoma of the distal esophagus and esophagogastric junction, remains uncertain. this paper reviews the current scientific literature with emphasis on the protective correlation between H. Pylori infection and BE, and demonstrates that a causal relathionship has not been disproved with certainty. Furthermore, H. Pylori infection could pose a risk for the onset of gastroesophageal reflux disease (GERD), which could in turn trigger BE, a precancerous lesion and…

SEDENTARINESS AND EDUCATION CONTRIBUTE SIGNIFICANTLY TO SOCIOECONOMIC INEQUALITIES IN NON-COMMUNICABLE DISEASES

2018

In Europe, the main non-communicable diseases (NCDs), including diabetes, cardiovascular diseases, cancer, chronic respiratory diseases and mental disorders, all together account for an estimated 86% of the deaths and 77% of the disease burden. Of the six WHO regions, Europe is the most affected by NCDs [1]. The detection and control of physiological and behavioral risk factors (BRFs) remain the essential preventive strategy to counteract not only the average population’s exposure to the main NCDs, but also socioeconomic inequalities, which are related to chronic diseases. The scope of this work is to investigate socioeconomic inequalities among the European elderly in NCDs and BRFs for NCD…

Improving the Traditional Measures of Agglomeration with Neighbouring Effects

2009

The traditional measures of concentration are based on the hypothesis that agglomeration forces among plants appear only inside of a single area and they do not have any effect outside of it. Instead, it is reasonable thinking to the existence of factors exerting their effects not only within the territory where they were originated but, in the meantime, producing spillovers into neighbouring areas. Building on this assumption, this paper contributes to the agglomeration literature by proposing an extension of the traditional agglomeration measures that account for externalities that cross the barriers of the geographical units under analysis. So, we want to examine the spatial dependence a…