1,721,012 research outputs found
Characterization of hourly NOx atmospheric concentrations near the Venice International Airport with additive semi-parametric statistical models
No full textAn additive modeling approach is employed to provide a statistical description of hourly variation in concentrations of NOx measured in proximity of the Venice “Marco Polo” International Airport, Italy. Differently from several previous studies on airport emissions based on daily time series, the paper analyzes hourly data because variations of NOx concentrations during the day are informative about the prevailing emission source. The statistical analysis is carried out using a one-year time series. Confounder effects due to seasonality, meteorology and airport traffic volume are accounted for by suitable covariates. Four different model specifications of increasing complexity are considered. The model with the aircraft source expressed as the NOx emitted near the airport is found to have the best predictive quality. Although the aircraft source is statistically significant, the comparison of model-based predictions suggests that the relative impact of aircraft emissions to ambient NOx concentrations is limited and the road traffic is the likely dominant source near the sampling point
Tecniche fisiche di indagine e loro potenziale applicazione in tematiche attinenti alle scienze della Terra
Full text linkThe main objective of this PhD thesis is to use, exploring their potential, some physical techniques of investigation not covered in the usual experimental research in Earth Sciences (XPS, EXAFS, IBIL). Some samples of road dust were characterized, collected inside the ventilation air shaft of Traforo del San Bernardo tunnel, which is an ideal sampling site to study particulate from motor vehicles. These samples were also analyzed with the techniques ICP-OES, ICP-MS, as well as with a standard sedigraphic technique.L’obiettivo principale di questa tesi di dottorato è di utilizzare, esplorandone le potenzialità, alcune tecniche fisiche di indagine che non rientrano nella prassi sperimentale della ricerca in Scienze della Terra (XPS, EXAFS, IBIL), caratterizzando alcuni campioni di road dust raccolti all’interno dell’impianto di aerazione forzata del traforo del San Bernardo che è un sito di campionamento ideale per lo studio del particolato emesso dai veicoli a motore. Questi campioni sono stati inoltre analizzati con le tecniche ICP-OES, ICP-MS e una tecnica sedigrafica standard
Multi-edge X-ray absorption spectroscopy study of road dust samples from a traffic area of Venice using stoichiometric and environmental references
No full textThe appropriate selection of representative pure compounds to be used as reference is a crucial step for successful analysis of X-ray absorption near edge spectroscopy (XANES) data, and it is often not a trivial task. This is particularly true when complex environmental matrices are investigated, being their elemental speciation a priori unknown. In this paper, an investigation on the speciation of Cu, Zn, and Sb based on the use of conventional (stoichiometric compounds) and non-conventional (environmental samples or relevant certified materials) references is explored. This method can be useful in when the effectiveness of XANES analysis is limited because of the difficulty in obtaining a set of references sufficiently representative of the investigated samples. Road dust samples collected along the bridge connecting Venice to the mainland were used to show the potentialities and the limits of this approach
Ion beam induced luminescence analysis of defect evolution in lithium fluoride under proton irradiation
No full textIon beam induced luminescence (IBIL) spectra of pure LiF under irradiation by a 2 MeV proton beam were analyzed as a function of the dose in order to deepen the kinetic mechanisms underlying the formation of luminescent point defects. The intensity evolution with dose at several emission wavelengths has been studied within a wide spectral interval, from ultraviolet (UV) to near infrared (NIR), and their different change rates have been correlated to the electronic defect formation processes. The intensity at few selected wavelengths was analyzed with a multiple linear regression (MLR) method in order to demonstrate that a linear calibration curve can be obtained and that an on-line optical dose monitor for ion beams can be realized.Ion beam induced luminescence (IBIL) spectra of pure LiF under irradiation by a 2 MeV proton beam were analyzed as a function of the dose in order to deepen the kinetic mechanisms underlying the formation of luminescent point defects. The intensity evolution with dose at several emission wavelengths has been studied within a wide spectral interval, from ultraviolet (UV) to near infrared (NIR), and their different change rates have been correlated to the electronic defect formation processes. The intensity at few selected wavelengths was analyzed with a multiple linear regression (MLR) method in order to demonstrate that a linear calibration curve can be obtained and that an on-line optical dose monitor for ion beams can be realized
Sources and distribution of tracer elements in road dust: The Venice mainland case of study
No full textRoad dust is an important non-exhaust traffic source of atmospheric particulate matter, from re-suspension of finer particles carried out by wind and traffic flow. Particles of road dust have both natural and anthropogenic origin; the latter is characterized by higher concentrations of several pollutants and are significantly emitted by other non-exhaust traffic source such as the brake and road wear process. Therefore the discrimination between atmospheric particles directly emitted from abrasion process and those related to re-suspension is currently an open issue.
Unlike the exhaust sources related to the fuel combustion, the non-exhaust emissions are not regulated by Communitarian Directives, although their percentage contribution is becoming more relevant due to the recent technological upgrades in the automotive field, focused on the reduction of exhaust emissions.
In this work we studied the morphology and the chemical composition of road dust particles collected on urban, sub-urban and rural roads of Venice mainland (Northern Italy) in August 2013. Results of SEM-EDS and ICP-OES were processed with statistical tools (i.e., enrichment factors and principal components analysis) in order to identify the main pollutant sources affecting the monitored areas. Peculiar associations among Cr, Mn, Zn, Cu, Fe suggested brake pads and tires wear as the dominant source of these elements, whereas the presence of Pb, Co, Ba, Ti was attributed to the tear of the painted horizontal signals. Moreover, the presence of particles originated from the latter source was also confirmed by the presence of glass beads with diameters ranging from 20 μm to 250 μm
Yttrium silicate and oxonitridosilicate luminescent materials from a silicone resin and nano-sized fillers
No full textYttrium silicate and oxonitridosilicate ceramic powders have been successfully prepared by heat treatment, at 1300-1400 °C, of a silicone resin embedding Y2O3 nano-sized particles as reactive fillers. Nano-sized RE-oxides (Eu2O3, CeO2), used as secondary additives, promoted the development of apatite phase, in both air and N2 atmosphere. For treatments in nitrogen, the only crystal phase consisted of yttrium nitrogen apatite, mixed with amorphous silicon oxycarbide (SiOC). Eu-doped and Ce-doped yttrium silicates were characterized by means of UV-visible luminescence and ion beam induced luminescence (IBIL). Strong luminescence features were observed, depending on the conditions of thermal treatment.Yttrium silicate and oxonitridosilicate ceramic powders have been successfully prepared by heat treatment, at 1300–1400 °C, of a silicone resin embedding Y2O3 nano-sized particles as reactive fillers. Nano-sized RE-oxides (Eu2O3, CeO2), used as secondary additives, promoted the development of apatite phase, in both air and N2 atmosphere. For treatments in nitrogen, the only crystal phase consisted of yttrium nitrogen apatite, mixed with amorphous silicon oxycarbide (SiOC). Eu-doped and Ce-doped yttrium silicates were characterized by means of UV–visible luminescence and ion beam induced luminescence (IBIL). Strong luminescence features were observed, depending on the conditions of thermal treatment
Improving the Analysis of Ion Beam Induced Luminescence Spectra of Samples with High Radiation Resistance
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