348 research outputs found
Studio del trasporto e diffusione di inquinanti radioattivi nel suolo e sottosuolo
No full textNel presente lavoro è stato affrontato lo studio del trasporto e della destinazione degli inquinanti radioattivi nel suolo e sottosuolo tramite l’utilizzo della piattaforma software FRAMES ed in particolare del modulo MEPAS.
La prima parte dell’opera è stata dedicata alla trattazione della radioattività, analizzandone gli aspetti generali e soffermandosi sul concetto di rifiuto radioattivo e sulla gestione e sullo smaltimento dello stesso.
Si sono poi analizzati i principali modelli di trasporto per la valutazione del destino dei contaminanti nell’ambiente, fase complessa nella valutazione del rischio o in qualsiasi altra valutazione di impatto ambientale. Lo studio complessivo del problema ha richiesto la suddivisioni in tre momenti distinti, che si riferiscono al modello concettuale di analisi di rischio:
le sorgenti di contaminazione;
le vie di migrazione;
i bersagli di contaminazione
INTEGRATED APPROACH COMBINING DIRECT SURVEY AND OBSERVATION IN DAMAGE ANALYSIS IN CASE OF SOIL SETTLEMENT
No full textNowadays, different methods are used to study historical masonry buildings. Among these, for the study of architectures with complex geometry, the effectiveness of an integrated approach, that is a method of analysis combining different disciplines, is increasingly evident.The aim of this paper is to show the importance of combining direct observation with structural analysis in order to understand the level of safety in buildings with composite geometries.This paper describes the analysis executed in the XX century parish church of San Bernardino in Sesto Calende (Va), which displays serious cracks and damage caused by soil settlements.The integrated approach starts with historical analysis, by consulting all available documents and drawings. To understand the geometry of the structure a new survey has been made and a three-dimensional digital representation was modeled, by which better deriving the weight of all the elements in the construction, and to find the correct actions and thrust on arches, columns, bases and foundation. All this data was used in the structural analysis based on the static method of limit analysis. For the material behavior the model proposed by J. Heyman (1966) is used, considering the “no tension” failure criterion. The static theorem of minimum reactions for settled states enunciated by M. Como (2010) is employed for the analysis of soil settlement effects on the building’s response.The work shows how direct survey of geometry and damage of a complex building has an effective importance in the structural analysis to ensure Cultural Heritage preservation and safety.</p
The Outsourcing Wage Gap: Exploring the Interplay of Gender and Tasks Along the Job Distribution
No full textStructural and optical investigation of plasma deposited silicon carbon alloys: Insights on Si-C bond configuration using spectroscopic ellipsometry
No full textStatic analysis of masonry polygonal domes with membrane forces
No full textMasonry polygonal domes are parts of several historic monuments and masonry buildings. The analysis of
polygonal domes with a static approach is here presented, considering the structure made of vault cells and ribs.
The vaults are portions of a cylindrical surface with single curvature in the meridian direction, and translation of
the generatrix curve in the direction of the cylinder axis. The system is divided into rigid elements with interfaces.
The first part of the work regards the geometry of the rigid elements, in particular the angles that
characterize the shape of these. Then the equilibrium equations applied to every element are presented, with a
procedure to calculate the membrane response for the self-weight in a non-redundant system, under symmetry
conditions. The sum of the solution for the vaults is combined with effects of the weight of ribs and radial walls.
The use of the equilibrium solution for pointed domes, domes with a lantern and oculus or additional load to the
dome self-weight is shown. A limit analysis static approach is formulated calculating the maximum load relative
to the equilibrium of the rigid elements considering the interfaces tensile strength and limited cohesion and
friction for the shear resistanc
An optical study of the correlation between growth kinetics and microstructure of mu c-Si grown by SiH(4)-H(2)PECVD
No full textSynthesis and characterization of plasmon resonant gold nanoparticles and graphene for photovoltaics
No full textHere we discuss the use in solar cells of graphene grown by chemical vapor deposition (CVD) and of plasmonic gold nanoparticles (Au NPs) deposited by sputtering. The Au NPs have been coupled with a-Si heterojunction solar cells, with an organic active layer used in organic photovoltaics, and with graphene. Extensive characterization of those three systems by the optical technique of spectroscopic ellipsometry, which is suitable to monitor and analyze the plasmon resonance of the Au NPs, by the microstructural technique of Raman spectroscopy, which is suitable to analyze graphene properties and doping, and by atomic force microscopy has been carried out. Those techniques highlighted interactions between Au NPs and silicon, polymer and graphene, which lead to variation in the plasmon resonance of Au NPs and consequently in the characteristics of the Au NPs/Si, Au NPs/polymer and Au NPs/graphene hybrids. Specifically, we found that an optimal size and density of Au NPs are able to enhance the efficiency of c-Si/a-Si heterojunction solar cells and that exceeding with Au NPs size and density causes device shortcut because of interface interdiffusion between silicon and gold. To discuss organic photovoltaics, Au NPs have been combined with an electro-donating conjugated polymer, the poly[1,4bis(2-thienyl)-2,5-bis-(2-ethyl-hexyloxyphenylenes)]. We found that there is a strong correlation between the thickness and morphology of the organic active layer, which affects the energy and amplitude of the Au NPs plasmon resonance. Finally, Au NPs have been deposited on graphene. We found that Au NPs show the plasmon resonance in the region where graphene is transparent and also yield p-type doping of graphene decreasing its sheet resistance. © 2012 Elsevier B.V. All rights reserved
PHEMA-based thin hydrogel films for biomedical applications
No full textPoly(2-hydroxyethyl methacrylate) based thin coatings were electro-synthesized by cyclic voltammetry on Au-coated quartz crystal surfaces to study different solid–liquid interfacial processes. By varying the electrochemical parameters and the presence or not of a crosslinking agent, films were obtained with thicknesses ranging from 5 to 90 nm. Surface characterization was performed by X-ray photoelectron spectroscopy, atomic force microscopy, and static contact angle measurements. Using quartz crystal microbalance with dissipation monitoring to investigate the relationship between the film thickness and the swelling behavior, it was found that these characteristics can be modulated by varying either the number of voltammetric cycles or the presence of the crosslinker. Cell adhesion and biocompatibility tests indicate that these film coatings were suitable for biomedical applications
The hyperchromatic supranuclear stria corresponds to the golgi apparatus in nasal ciliated cells
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