Factors determining the most efficient spray distribution for marine cloud brightening Connolly, P. J.; McFiggans, G. B.; Wood, R. ...
Philosophical transactions - Royal Society. Mathematical, Physical and engineering sciences/Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences,
12/2014, Letnik:
372, Številka:
2031
Journal Article
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We investigate the sensitivity of marine cloud brightening to the properties of the added salt particle distribution using a cloud parcel model, with an aim to address the question of, what is the ...most efficient particle size distribution that will produce a desired cooling effect? We examine the effect that altering the aerosol particle size distribution has on the activation and growth of drops, i.e.the Twomey effect alone, and do not consider macrophysical cloud responses that may enhance or mitigate the Twomey effect. For all four spray generation methods considered, Rayleigh jet; Taylor cone jet; supercritical fluid; and effervescent spray, salt particles within the median dry diameter range Dm30100nm are the most effective range of sizes. The Rayleigh jet method is also the most energy efficient overall. We also find that care needs to be taken when using droplet activation parametrizations: for the concentrations considered, Aitken particles do not result in a decrease in the total albedo, as was found in a recent study, and such findings are likely to be a result of the parametrizations' inability to simulate the effect of swollen aerosol particles. Our findings suggest that interstitial aerosol particles play a role in controlling the albedo rather than just the activated cloud drops, which is an effect that the parametrization methods do not consider.
Timing performance of a multi-pad PICOSEC-Micromegas detector prototype Aune, S.; Bortfeldt, J.; Brunbauer, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2021, Letnik:
993, Številka:
C
Journal Article
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The multi-pad PICOSEC-Micromegas is an improved detector prototype with a segmented anode, consisting of 19 hexagonal pads. Detailed studies are performed with data collected in a muon beam over four ...representative pads. We demonstrate that such a device, scalable to a larger area, provides excellent time resolution and detection efficiency. As expected from earlier single-cell device studies, we measure a time resolution of approximately 25 picoseconds for charged particles hitting near the anode pad centres, and up to 30 picoseconds at the pad edges. Here, we study in detail the effect of drift gap thickness non-uniformity on the timing performance and evaluate impact position based corrections to obtain a uniform timing response over the full detector coverage.
With their capacity for real time monitoring and spatial mapping, implantable sensors are becoming an increasingly important aspect of next generation precision healthcare. Microfabricated sensor ...systems are a popular choice, owing to their capacity for miniaturisation, repeatable mass manufacture, and numerous pre-existing sensor archetypes. Despite the drive for development, packaging these sensors for the environment within the body, as well as the implantation process itself, presents a significant challenge. This paper presents microelectronic test structures, which can be used to assess, compare, and optimise implantable packaging solutions in a standardised manner. The proposed structures are used to investigate: (i) the capacity of the material to be patterned, (ii) the permeability of the insulation material, (iii) adhesion of the encapsulant to the die, and (iv) the physical robustness of the package to implantation through a needle. They are used to characterise an example packaging strategy, using biocompatible epoxy-resin. In addition, a method of optimising the packaging performance using the test structures is presented.
•Plastics introduction into the economy has led to decoupling of MSW generation growth and PCE.•The decoupling has been quantitatively identified to begin in the late 1990s (i.e. 1997–2000).•If ...plastics were not used the MSW generation rate rises equally with PCE.
Analysis of data from the US Environmental Protection Agency (EPA) on municipal solid waste (MSW) generation rates correlated to personal consumption expenditure (PCE) uncovers a decoupling event occurring between 1997 and 2000. A comparison of waste generation rates for each material category found in MSW reveals that plastics increased by nearly 84 times from 1960 to 2013 while total MSW increased only 2.9 times. The increase in plastic waste generation coincides with a decrease in glass and metal found in the MSW stream. In addition, calculating the material substitution rates for glass, metal and other materials with plastics in packaging and containers demonstrates an overall reduction by weight and by volume in MSW generation of approximately 58% over the same time period. A quantitative calculation of a scenario where plastics were not used in packaging and containers to replace glass, metal, and other materials demonstrates that MSW generation rate rises equally with PCE. Therefore, this study has determined that the increase of plastic use is a contributing factor to the decoupling of MSW generation from PCE.
Because subintimal angioplasty (SA) is a technique that can achieve recanalization of long arterial occlusions, it is considered an alternative to lower limb bypass operations. The aim of this ...prospective study was to identify the risk factors that affect patency of SA in patients suffering from critical limb ischemia (CLI).
51 consecutive infrainguinal SA were done in 46 patients suffered from CLI. The patients were followed-up with regular duplex scans up to 12 months post-intervention. Sex, atherosclerosis risk factors, and some technical details of the procedure (number of patent run-off vessels after the procedure, length and re-entry point of angioplasty) were examined as potential risk factors of patency, using survival analysis statistical techniques.
The overall patency rate at 12 months post-intervention was 50%. According to Cox-regression analysis, the factors that affect patency were the number of run-off vessels and the length of occlusion. Patients with two or three run-off vessels had a hazard of occlusion of 0.30 (
P
=
.027) compared to those who had one run-off vessel. The 12-months patency in patients with more than one run-off vessels was 81% vs. 25% in patients with one run-off vessel. Regarding the length of angioplasty, the hazard of reocclusion was 1.02 for every centimeter of occlusion (
P
=
.049).
The number of patent run-off crural vessels after the angioplasty and the length of occlusion are significant risk factors for reocclusion of infrainguinal SA in patients with CLI. Trying to recanalize more than one run-off vessels could raise the SA patency.
We investigate the sensitivity of marine cloud brightening to the properties of the added salt particle distribution using a cloud parcel model, with an aim to address the question of, 'what is the ...most efficient particle size distribution that will produce a desired cooling effect?' We examine the effect that altering the aerosol particle size distribution has on the activation and growth of drops, i.e. the Twomey effect alone, and do not consider macrophysical cloud responses that may enhance or mitigate the Twomey effect. For all four spray generation methods considered, Rayleigh jet; Taylor cone jet; supercritical fluid; and effervescent spray, salt particles within the median dry diameter range Dm = 30–100 nm are the most effective range of sizes. The Rayleigh jet method is also the most energy efficient overall. We also find that care needs to be taken when using droplet activation parametrizations: for the concentrations considered, Aitken particles do not result in a decrease in the total albedo, as was found in a recent study, and such findings are likely to be a result of the parametrizations' inability to simulate the effect of swollen aerosol particles. Our findings suggest that interstitial aerosol particles play a role in controlling the albedo rather than just the activated cloud drops, which is an effect that the parametrization methods do not consider.
This paper compares electrical, optical, and atomic force microscope (AFM) measurements of critical dimension (CD) made on a chrome on quartz photomask. Test structures suitable for direct, on-mask ...electrical probing have been measured using the above three techniques. These include cross-bridge linewidth structures and pairs of Kelvin bridge resistors designed to investigate dimensional mismatch. Overall, the results show very good agreement between the electrical measurements and those made with a calibrated CD-AFM system, while the optical metrology system overestimates the measured width. The uncertainty in each of the measurements has been considered, and for the first time an attempt has been made to describe the levels and sources of uncertainty in the electrical measurement of CD on advanced binary photomasks.
This paper presents a comparison of optical and electrical techniques for critical dimension (CD) metrology on binary and alternating aperture phase-shifting masks. Measurements obtained from on-mask ...electrical CD structures are compared with optical measurements made using a deep ultraviolet mask metrology system. The results show that the presence of alternating phase-shifting trenches between the chrome blocking features has a detrimental effect on the optical measurements and that this effect strongly depends on the depth of the trenches. In addition, the optical metrology system appears to have problems with the measurement of the narrowest isolated features due to calibration related issues. Electrical CD measurements are seen as a way of probing the limits of optical tool calibration and for highlighting and managing the need to extend the complexity of the calibration schedule.
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