Search results for "Dispersion"
showing 10 items of 1101 documents
Temperature effect on phase state and reactivity controls atmospheric multiphase chemistry and transport of PAHs
2017
Atmospheric refrigerator increases the global transport and health risks of carcinogenic PAHs.
Two-days ahead prediction of daily maximum concentrations of SO2, O3, PM10, NO2, CO in the urban area of Palermo, Italy
2007
Abstract Artificial neural networks are functional alternative techniques in modelling the intricate vehicular exhaust emission dispersion phenomenon. Pollutant predictions are notoriously complex when using either deterministic or stochastic models, which explains why this model was developed using a neural network. Neural networks have the ability to learn about non-linear relationships between the used variables. In this paper a recurrent neural network (Elman model) based forecaster for the prediction of daily maximum concentrations of SO2, O3, PM10, NO2, CO in the city of Palermo is proposed. The effectiveness of the presented forecaster was tested using a time series recorded between …
Volcanic plume monitoring at Mount Etna by diffusive (passive) sampling
2004
[1] This paper reports the use of diffusive tubes in determining HF, HCl, and SO2 in the volcanic plume of Mount Etna in an attempt to highlight the potential of this method in studying volcanoes. In a first application a network of 18 diffusive tubes was installed on Etna's flanks, aimed at evaluating the atmospheric dispersion of the volcanic plume on a local scale. Results showed a monotonic decrease in volatile air concentrations with distance from the craters (HF from 0.15 to <0.003 μmol m−3, HCl from 2 to <0.01 μmol m−3, and SO2 from 11 to 0.04 μmol m−3), revealing the prevalently volcanic contribution. Matching of SO2/HCl and HCl/HF volatile ratios with contemporaneous measurements a…
MACC regional multi-model ensemble simulations of birch pollen dispersion in Europe
2015
Abstract. This paper presents the first ensemble modelling experiment in relation to birch pollen in Europe. The seven-model European ensemble of MACC-ENS, tested in trial simulations over the flowering season of 2010, was run through the flowering season of 2013. The simulations have been compared with observations in 11 countries, all members of the European Aeroallergen Network, for both individual models and the ensemble mean and median. It is shown that the models successfully reproduced the timing of the very late season of 2013, generally within a couple of days from the observed start of the season. The end of the season was generally predicted later than observed, by 5 days or more…
An evaluation of the estimation of road traffic emission factors from tracer studies
2010
Road traffic emission factors (EFs) are one of the main sources of uncertainties in emission inventories; it is necessary to develop methods to reduce these uncertainties to manage air quality more efficiently. Recently an alternative method has been proposed to estimate the EFs. In that work the emission factors were estimated from a long term tracer study developed in Ho Chi Minh City (HCMC) Vietnam. A passive tracer was continuously emitted from a finite line source placed in one side of an urban street canyon. Simultaneously, the resulting tracer concentrations were monitored at the other side of the street. The results of this experiment were used to calculate the dispersion factors an…
Análisis de las publicaciones españolas sobre Documentación e Informática Médica
1994
Se estudia la producción española de documentación e información médicas, en sus distintas áreas de especialización, hasta el año 1991. Se analiza el crecimiento de la producción de los diferentes tipos de documentos sobre la disciplina, así como las materias, instituciones de procedencia y distribución geográfica . Los resultados muestran la gran dispersión de los trabajos sobre el tema y el predominio de los estudios dedicados a la documentación clínica, producidos en instituciones hospitalarias.
A hydrodynamic water quality model for propagation of pollutants in rivers.
2010
Numerical modelling can be a useful tool to assess a receiving water body's quality state. Indeed, the use of mathematical models in river water quality management has become a common practice to show the cause-effect relationship between emissions and water body quality and to design as well as assess the effectiveness of mitigation measures. In the present study, a hydrodynamic river water quality model is presented. The model consists of a quantity and a quality sub-model. The quantity sub-model is based on the Saint Venant equations. The solution of the Saint Venant equations is obtained by means of an explicit scheme based on space-time conservation. The method considers the unificatio…
A miniaturized method for estimating di(2-ethylhexyl) phthalate in bivalves as bioindicators.
2012
This work has developed a miniaturized method based on matrix solid phase dispersion (MSPD), using C18 as dispersant and acetonitrile-water as eluting solvent, for the analysis of di(2-ethylhexyl) phthalate (DEHP) in biota samples by capillary liquid chromatography coupled to in-tube solid phase microextraction and diode array detection. Recovery studies showed that the combination of C18-Florisil® was optimal using low amount of samples (0.1 g) and with low volumes of acetonitrile-water (2.6 mL 1:3.25, v/v). The sample is processed in less than 30 min, no evaporation step is required. The proposed method was applied to the analysis of DEHP in mussels and of the coastal waters in which they…
Colloidal stability of halloysite clay nanotubes
2019
Abstract The colloidal stability of halloysite clay nanotubes dispersion is reviewed showing the strategy and the mechanism to obtain stable systems in water and apolar solvents. The selective modification of halloysite inner/outer surfaces can be achieved by exploiting electrostatic interactions. The adsorption of anionic surfactants onto the halloysite cavity allows generating inorganic cylindrical micelles that can be separated from the solvent. On the other hand, the functionalization of halloysite shell by positively charged surfactants drives to obtain stable water-in-oil emulsions. The interactions with ionic and nonionic polymers alters the dispersability of halloysite due to electr…
Single-Polarization Double Refraction in Plasmonic Crystals: Considerations on Energy Flow
2014
We examined the optical properties of nanolayered metal-dielectric lattices. At subwavelength regimes, the periodic array of metallic nanofilms demonstrates nonlocality-induced double refraction, conventional positive and as well as negative. In particular, we report on energy-flow considerations concerning both refractive behaviors concurrently. Numerical simulations provide transmittance of individual beams in Ag-TiO2 metamaterials under different configurations. In regimes of the effective-medium theory predicting elliptic dispersion, negative refraction may be stronger than the expected positive refraction. This research was funded by the Spanish Ministry of Economy and Competitiveness …