Source apportionment of PM_2.5 in Cork Harbour, Ireland using a combination of single particle mass spectrometry and quantitative semi-continuous measurements

An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed for the measurement of the size resolved chemical composition of single particles at a site in Cork Harbour, Ireland for three weeks in August 2008. The ATOFMS was co-located with a suite of semi-continuous instrumentation for the measurement of particle number, elemental carbon (EC), organic carbon (OC), sulfate and particulate matter smaller than 2.5 μm in diameter (PM_2.5). The temporality of the ambient ATOFMS particle classes was subsequently used in conjunction with the semi-continuous measurements to apportion PM_2.5 mass using positive matrix factorisation. The synergy of the single particle classification procedure and positive matrix factorisation allowed for the identification of six factors, corresponding to vehicular traffic, marine, long-range transport, various combustion, domestic solid fuel combustion and shipping traffic with estimated contributions to the measured PM_2.5 mass of 23%, 14%, 13%, 11%, 5% and 1.5% respectively. Shipping traffic was found to contribute 18% of the measured particle number (20–600 nm mobility diameter), and thus may have important implications for human health considering the size and composition of ship exhaust particles. The positive matrix factorisation procedure enabled a more refined interpretation of the single particle results by providing source contributions to PM_2.5 mass, while the single particle data enabled the identification of additional factors not possible with typical semi-continuous measurements, including local shipping traffic

Source apportionment of PM2.5 in Cork Harbour, Ireland using a combination of single particle mass spectrometry and quantitative semi-continuous measurements

An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed for the measurement of the size resolved chemical composition of single particles at a site in Cork Harbour, Ireland for three weeks in August 2008. The ATOFMS was co-located with a suite of semi-continuous instrumentation for the measurement of particle number, elemental carbon (EC), organic carbon (OC), sulfate and particulate matter smaller than 2.5 μm in diameter (PM2.5). The temporality of the ambient ATOFMS particle classes was subsequently used in conjunction with the semi-continuous measurements to apportion PM2.5 mass using positive matrix factorisation. The synergy of the single particle classification procedure and positive matrix factorisation allowed for the identification of six factors, corresponding to vehicular traffic, marine, long-range transport, various combustion, domestic solid fuel combustion and shipping traffic with estimated contributions to the measured PM2.5 mass of 23%, 14%, 13%, 11%, 5% and 1.5% respectively. Shipping traffic was found to contribute 18% of the measured particle number (20–600 nm mobility diameter), and thus may have important implications for human health considering the size and composition of ship exhaust particles. The positive matrix factorisation procedure enabled a more refined interpretation of the single particle results by providing source contributions to PM2.5 mass, while the single particle data enabled the identification of additional factors not possible with typical semi-continuous measurements, including local shipping traffic

On-chip circularly polarized circular loop antennas utilizing 4H-SiC and GaAs substrates in the Q/V band

This paper presents a comprehensive assessment of the performance of on-chip circularly polarized (CP) circular loop antennas that have been designed and fabricated to operate in the Q/V frequency band. The proposed antenna design incorporates two concentric loops, with the outer loop as the active element and the inner loop enhancing the CP bandwidth. The study utilizes gallium arsenide (GaAs) and silicon carbide (4H-SiC) semiconductor wafer substrates. The measured results highlight the successful achievement of impedance matching at 40 GHz and 44 GHz for the 4H-SiC and GaAs substrates, respectively. Furthermore, both cases yield an axial ratio (AR) of less than 3 dB, with variations in bandwidths and frequency bands contingent upon the dielectric constant of the respective substrate material. Moreover, the outcomes confirm that utilizing 4H-SiC substrates results in a significantly higher radiation efficiency of 95%, owing to lower substrate losses. In pursuit of these findings, a 4-element circularly polarized loop array antenna has been fabricated for operation at 40 GHz, employing a 4H-SiC wafer as a low-loss substrate. The results underscore the antenna’s remarkable performance, exemplified by a broadside gain of approximately 9.7 dBic and a total efficiency of circa 92%. A close agreement has been achieved between simulated and measured results

Geomorphologic clues on the kinematics of fault-related folds: example of the Southern Tunisian Atlas. In Theory and Application of Fault-Related Folding in Foreland Basins

International audienc

Geomorphologic clues on the kinematics of fault-related folds: example of the Southern Tunisian Atlas. In Theory and Application of Fault-Related Folding in Foreland Basins

International audienc

Scorch arisen prediction through elastomer flow in extrusion die

International audienc

The Heterogeneous Kinetics of the Reactions ClONO

The kinetics and mechanism of the title heterogeneous halogen exchange reactions of potential atmospheric importance have been studied under molecular flow conditions in a FEP Teflon-coated Knudsen flow reactor on HX (X = Cl, Br, I) - doped ice condensed from the vapor phase under conditions of several formal monolayers of HX coverage at approximately 200 K. In addition, the halogen exchange reactions involving the expected primary reaction products BrCl, ICl and IBr of the above mixed anhydrides with HX-doped ice have been studied at 200 K as well. The uptake coefficient γ for the heterogeneous reaction ClONO2 + HBr on ice is 0.56±0.11 and Cl2 and Br2 are formed in yields of 100% and 66 to 80%, respectively, in the range 180 to 200 K. The γ value for the reaction ClONO2 + HI on ice is 0.30±0.02 at 200 K with Cl2 being the main product appearing after an induction time. The primary product ICl is formed at the same time as Cl2 whereas HOCl appears at a later time under conditions of waning HI supply. The γ value for the reaction BrONO2 + HI on ice is 0.40±0.02 at 200 K with Br2 being the main product observed after a short delay. The primary product IBr is observed without delay, whereas HOBr is observed at a later time once HBr has reacted. The mechanism of the reactions of the interhalogens BrCl, ICl and IBr with HX on ice at 200 K involves the formation of trihalide ions at the ice interface which is consistent with the observed significant negative temperature dependence for the reaction ICl + HBr on ice in the range 180 to 205 K as well as for the reaction BrCl + HBr between 190 and 200 K. The uptake coefficient γ for each of the interhalogens increases from ice to HI-doped ice in the order of increasing molecular weight of HX with the exception of ICl, whose g attains a limiting value of γ = 0.32±0.05. A halogen exchange reaction on ice has been observed in cases where the most stable hydrohalic acid could be formed: HCl > HBr > HI. A propensity for the formation of the homonuclear halogen molecule in the reactions of halogen nitrates with HX-doped ice has been explained by the occurrence of fast secondary reactions of the primary interhalogen product at the HX/ice interface

Résonateur reconfigurable à base de lignes couplées à éléments d'accord intégrés sur substrat silicium

International audienceThis paper presents a particular technique of reconfiguration of coupled line resonators. The reconfigurability is obtained by doping one or more parts of the silicon substrate located at the level of the coupled lines, thus creating one or more distributed diodes. The entire circuit goes through a co-design offering great flexibility and a considerable reduction in losses linked to the interconnection between the passive and active element. A first two-state resonator is presented, it has a resonance frequency close to 2.5 GHz in the OFF state and a frequency of 1.5 GHz in the ON state; the latter being adjustable as a function of the position of the doped zone. A second three-state resonator is also presented, its resonant frequency switches from 2.5 GHz in the OFF state, to 1.62 GHz in the ON1 state then to 2.13 GHz in the ON2 state.-Ce papier présente une technique particulière de reconfiguration de résonateurs à lignes couplées. La reconfigurabilité est obtenue par le dopage d'une ou plusieurs parties du substrat silicium situées au niveau des lignes couplées, créant ainsi une ou plusieurs diodes distribuées. L'intégralité du circuit passe par une coconception offrant une grande flexibilité et une réduction considérable des pertes liées à l'interconnexion entre l'élément passif et actif. Un premier résonateur deux états est présenté, il possède une fréquence de résonance proche de 2,5 GHz à l'état OFF et une fréquence de 1,5GHz à l'état ON ; cette dernière étant ajustable en fonction de la position de la zone dopée. Un deuxième résonateur trois états est également présenté, sa fréquence de résonance commute de 2,5 GHz à l'état OFF, à 1,62 GHz à l'état ON1 puis à 2,13 GHz à l'état ON2