In Situ Samplings and Remote Sensing Measurements to Characterize Aerosol Properties over Southeast Italy

Abstract Ground-based particulate matter (PM) samplers, an XeF Raman lidar operating in the framework of the European Aerosol Research Lidar Network (EARLINET), and a sun/sky radiometer operating in the framework of the Aerosol Robotic Network (AERONET) have been used to characterize vertical profiles, optical and microphysical properties, and chemical composition of aerosols during the 29 June–1 July 2005 dust outbreak that occurred over the central-eastern Mediterranean. Aerosol backscatter coefficient, total depolarization, and lidar ratio vertical profiles revealed that a well-mixed dust layer extending from ∼0.5 to 6 km was present over southeastern Italy on 30 June. Sun/sky radiometer measurements revealed a bimodal lognormal size distribution during all measurement days. The particle volume distribution was found to be well correlated either to the PM mass distribution measured at ground by a seven-stage cascade impactor and to the fine to total suspended PM mass ratio measured by ground-based PM samplers. Scanning electron microscopy and ion chromatography analyses on PM samples revealed that coarse-mode aerosols were mainly made of carbonate, aluminum-silicate, and sea salt particles. Carbon, sulfate, and nitrate particles were the main components of fine-mode aerosols representing more than 50% of the total aerosol load; the significant role of fine-mode anthropogenic particles during a dust event is highlighted. Finally, the potential capabilities of complementary measurements by passive and active remote sensing techniques and in situ observations to retrieve the vertical distribution of the particle number and mass concentration are analyzed and discussed

Modification of creep and low cycle fatigue behaviour induced by welding

In this work, the mechanical properties of Waspaloy superalloy have been evaluated in case of welded repaired material and compared to base material. Test program considered flat specimens on base and TIG welded material subjected to static, low-cycle fatigue and creep test at different temperatures. Results of uniaxial tensile tests showed that the presence of welded material in the gage length specimen does not have a relevant influence on yield strength and UTS. However, elongation at failure of TIG material was reduced with respect to the base material. Moreover, low-cycle fatigue properties have been determined carrying out tests at different temperature (room temperature RT and 538°C) in both base and TIG welded material. Welded material showed an increase of the data scatter and lower fatigue strength, which was anyway not excessive in comparison with base material. During test, all the hysteresis cycles were recorded in order to evaluate the trend of elastic modulus and hysteresis area against the number of cycles. A clear correlation between hysteresis and fatigue life was found. Finally, creep test carried out on a limited number of specimens allowed establishing some changes about the creep rate and time to failure of base and welded material. TIG welded specimen showed a lower time to reach a fixed strain or failure when a low stress level is applied. In all cases, creep behaviour of welded material is characterized by the absence of the tertiary creep

Relation of air mass source regions to PM10 mass concentrations using back trajectories

Abstract T06A195

Influenza del trasporto transfrontaliero nella composizione di campioni di TSP e PM2.5 : casi studio

Total Suspended Particulate (TSP) and PM2.5 samples simultaneously collected at a coastal site (40.4\ub0N; 18.1\ub0E) in the central Mediterranean are analyzed to investigate the relative role of ions (Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, Ca2+) and carbonaceous species in the fine (PM2.5) and coarse (TSP-PM2.5) sampled mass and contribute to the characterization of the Central Mediterranean particulate. A methodology is described to determine carbonate carbon (CC), organic carbon (OC), and elemental carbon (EC) levels from Thermal Optical Transmittance (TOT) measurements since carbonate particles may significantly contribute to the Mediterranean particulate. We have found that CC levels vary up to 1.7 \ub5g/m3 and 0.8 \ub5g/m3 in the coarse and fine fraction, respectively. OC and EC levels vary up to 3.0 \ub5g/m3 and 1.5 \ub5g/m3, respectively in the coarse fraction, and vary within the 2.2-10 \ub5g/m3 and 0.5-5 \ub5g/m3 range, respectively in the fine fraction. It is shown that OC levels may be quite overestimated mainly in the coarse fraction, if the CC contribution is not accounted for. CO32- levels (calculated by the CC concentrations) account on average for 6% and 13% of the fine (PM2.5) and coarse (TSP-PM2.5) sampled mass, respectively and allow balancing the anion deficit resulting from the ionic balance of ions detected by ion-chromatography (IC). Total carbon TC = (OC+EC) accounts on average for 31% and 5% of the fine and coarse mass, respectively. IC ions account for 37% and 17% of the fine and coarse mass, respectively. OC, EC, SO42-, NH4+, and K+ are the major components in the fine fraction, accounting on average for 84% of the analyzed PM2.5 mass. Marine- and crust-originated ions (Cl-, Mg2+, Na+, Ca2+, CO32-) and NO3- are mainly in the coarse fraction and represent on average 83% of the analyzed coarse mass . A discussion on the main reactions leading to the loss of ammonium particulate in the coarse fraction is provided. It is also shown that the Cl-/Na+ ratio varies within the 0.1-0.8 and 0.0-1.0 range in the fine and coarse particle fraction, respectively for the occurrence of Cl depletion processes

Geometric modelling of metallic foams

Purpose - The aim of this work is the development of a procedure able to model the highly irregular cellular structure of metallic foams on the basis of information obtained by X-ray tomographic analysis. Design/methodology/approach - The geometric modelling is based on the feature "pore" characterized by an ellipsoidal shape. The data for the geometric parameters of the instances are obtained with a methodology which is driven by the pore volume distribution curve. This curve shows how much the cells, whose diameter belongs to a given dimensional range, contribute to the reduction of the total volume. Findings - The presented methodology has been implemented into a CAD tool consisting of a Matlab routine identifying the instances of the feature "pore" and a CATIA's macro modelling the closed cells foam. Originality/value - The presented methodology allows to obtain in an automatic way the CAD model of the complex structure of closed cell aluminium foam approximating by considerable accuracy both the density and the volume distribution of the real foams

Studio del comportamento a trazione di giunti di testa in schiuma metallica

Questo lavoro descrive lo studio sperimentale svolto per valutare la resistenza a trazione di alcuni giunti in schiuma di alluminio ottenuti mediante diverse tipologie di collegamento, sia mediante bulloni che adesivi a base di resina epossidica. Sono state considerate diverse tipologie di disposizione dei bulloni e per ogni prova è stato ricavato il valore della forza massima necessaria per la rottura del collegamento. Le migliori prestazioni meccaniche si ottengono con il collegamento realizzato mediante due piastre coprigiunto e resina epossidica. Nel caso di collegamenti mediante bulloni, il carico trasmesso aumenta al crescere del numero di bulloni

Advection patterns and composition of TSP and PM2.5 samples over south-east Italy

24-hour Total Suspended Particulate (TSP) matter and PM2.5 samples have simultaneously been collected at a subrban site of South-East Italy to investigate the dependence of TSP and PM2.5 mass concentrations on long-range transported air masses

Aluminium foams structural modelling

The aim of this work is the development of microstructural numerical models of metallic foams. In particular, attention is focused on closed cell foam made of aluminium alloy. By means of a finite elements code, the material cellular structure was shaped in different ways: firstly the Kelvin cell, with both plane and curved walls; finally an ellipsoidal cell defined by random dimensions, position and orientation has been adopted as base unit. In order to validate the foam numerical models, static tests were performed to obtain the typical stress–strain curves and then compared with the numerical analysis results

Composition of Fine and Coarse Particles in a coastal site of the Central Mediterranean: carbonaceous specie contributions

Total Suspended Particulate (TSP) and PM2.5 samples simultaneously collected at a coastal site (40.4°N; 18.1°E) in the central Mediterranean are analyzed to investigate the relative role of ions (Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, Ca2+) and carbonaceous species in the fine (PM2.5) and coarse (TSP-PM2.5) sampled mass and contribute to the characterization of the Central Mediterranean particulate. A methodology is described to determine carbonate carbon (CC), organic carbon (OC), and elemental carbon (EC) levels from Thermal Optical Transmittance (TOT) measurements since carbonate particles may significantly contribute to the Mediterranean particulate. We have found that CC levels vary up to 1.7 $\mu$g/m3 and 0.8 $\mu$g/m3 in the coarse and fine fraction, respectively. OC and EC levels vary up to 3.0 $\mu$g/m3 and 1.5 $\mu$g/m3, respectively in the coarse fraction, and vary within the 2.2-10 $\mu$g/m3 and 0.5-5 $\mu$g/m3 range, respectively in the fine fraction. Hence, it is shown that OC levels may be quite overestimated mainly in the coarse fraction, if the CC contribution is not accounted for. CO32- levels (calculated from CC concentrations) account on average for 6% and 10% of the fine (PM2.5) and coarse (TSP-PM2.5) sampled mass, respectively and allow balancing the anion deficit resulting from the ionic balance of ions detected by ion-chromatography (IC). Total carbon TC = (OC+EC) accounts on average for 29% and 6% of the fine and coarse mass, respectively. IC ions account for 38% and 17% of the fine and coarse mass, respectively. OC, EC, SO42-, NH4+, and K+ are the major components in the fine fraction, accounting on average for 84% of the analyzed PM2.5mass. Marine- and crust-originated ions (Cl-, Mg2+, Na+, Ca2+, CO32-) and NO3- are mainly in the coarse fraction and represent on average 83% of the analyzed coarse mass. A discussion on the main reactions leading to the loss of ammonium particulate in the coarse fraction is provided. It is also shown that the Cl-/Na+ ratio varies within the 0.1-0.8 and 0.0-1.0 range in the fine and coarse particle fraction, respectively for the occurrence of Cl depletion processes

Modellazione strutturale di schiume di alluminio a celle aperte

Nel presente lavoro si espone uno studio numerico circa la modellazione di una schiuma di alluminio a celle aperte. In particolare, si esamina una schiuma M-pore di densità 10ppi soggetta ad una prova di compressione. Il modello numerico realizzato si basa sulla generazione casuale di nodi corrispondenti ai vertici di celle Kelvin e sulla unione di ognuno di tali vertici con i quattro punti più vicini. L’obiettivo è quello di riprodurre la struttura irregolare di una schiuma a celle aperte. Il confronto con i dati sperimentali a disposizione ha permesso di individuare il modello ottimale dopo aver analizzato una serie di parametri quali: il numero delle celle all’interno di un volume di riferimento, il raggio dei legamenti, la dimensione della cella elementare