lnstitut für Sensorik und Elektronik
Dauerhafte URI für die Sammlunghttps://irf.fhnw.ch/handle/11654/28068
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Ergebnisse nach Hochschule und Institut
Publikation Technology in motion(UKIP Media & Events Ltd., 2018) Simons, Gerd; Pospisek, Tomas01B - Beitrag in Magazin oder ZeitungPublikation Method of mounting a weigh-in-motion sensor in a roadway(Kistler Holding AG, 01.03.2019) Simons, Gerd; Pfluger, Kim12 - PatentPublikation Evidence for the role of organics in aerosol particle formation under atmospheric conditions(National Academy of Sciences, 19.01.2010) Metzger, Axel; Verheggen, Bart; Dommen, Josef; Duplissy, Jonathan; Prévôt, André S.H.; Weingartner, Ernest; Riipinen, Ilona; Kulmala, Markku; Spracklen, Dominick V.; Carslaw, Kenneth S.; Baltensperger, UrsNew particle formation in the atmosphere is an important parameter in governing the radiative forcing of atmospheric aerosols. However, detailed nucleation mechanisms remain ambiguous, as laboratory data have so far not been successful in explaining atmospheric nucleation. We investigated the formation of new particles in a smog chamber simulating the photochemical formation of H2SO4 and organic condensable species. Nucleation occurs at H2SO4 concentrations similar to those found in the ambient atmosphere during nucleation events. The measured particle formation rates are proportional to the product of the concentrations of H2SO4 and an organic molecule. This suggests that only one H2SO4 molecule and one organic molecule are involved in the rate-limiting step of the observed nucleation process. Parameterizing this process in a global aerosol model results in substantially better agreement with ambient observations compared to control runs.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Aerosol nucleation and growth in a mixture of sulfuric acid/alpha-pinene oxidation products at the CERN CLOUD chamber(AIP Publishing, 2013) Tröstl, Jasmin; Bianchi, Federico; Kürten, Andreas; Rondo, Linda; Simon, Mario; Sarnela, Nina; Jokinen, Tuija; Heinritzi, Martin; Dommen, Josef; Kirkby, Jasper; Weingartner, Ernest; Baltensperger, Urs; DeMott, Paul J.; O'Dowd, Colin D.The role of α-pinene in aerosol nucleation and growth was investigated using the CERN CLOUD chamber, a nano scanning mobility particle sizer (nanoSMPS) and several condensation particle counters (CPCs) with different diameter cut-offs. Different oxidation conditions for α-pinene - OH⋅ vs. ozone oxidation - were considered to investigate their contributions to particle nucleation and growth. Results from the latest CERN experiment from fall 2012 (CLOUD 7) are presented.04B - Beitrag KonferenzschriftPublikation Air cleaners and respiratory infections in schools. A modeling study using epidemiological, environmental, and molecular data(Oxford University Press, 30.12.2023) Banholzer, Nicolas; Jent, Philipp; Bittel, Pascal; Zürcher, Kathrin; Furrer, Lavinia; Bertschinger, Simon; Weingartner, Ernest; Ramette, Alban; Egger, Matthias; Hascher, Tina; Fenner, LukasAbstractBackgroundUsing a multiple-measurement approach, we examined the real-world effectiveness of portable HEPA-air filtration devices (air cleaners) in a school setting.MethodsWe collected environmental (CO2, particle concentrations), epidemiological (absences related to respiratory infections), audio (coughing), and molecular data (bioaerosol and saliva samples) over seven weeks during winter 2022/2023 in two Swiss secondary school classes. Using a cross-over study design, we compared particle concentrations, coughing, and the risk of infection with vs without air cleaners.ResultsAll 38 students (age 13−15 years) participated. With air cleaners, mean particle con-centration decreased by 77% (95% credible interval 63%−86%). There were no differences in CO2levels. Absences related to respiratory infections were 22 without vs 13 with air cleaners. Bayesian modeling suggested a reduced risk of infection, with a posterior probability of 91% and a relative risk of 0.73 (95% credible interval 0.44−1.18). Coughing also tended to be less frequent (posterior probability 93%). Molecular analysis detected mainly non-SARS-CoV-2 viruses in saliva (50/448 positive), but not in bioaerosols (2/105 positive) or HEPA-filters (4/160). The detection rate was similar with vs without air cleaners. Spatiotemporal analysis of positive saliva samples identified several likely transmissions.ConclusionsAir cleaners improved air quality, showed a potential benefit in reducing respiratory infections, and were associated with less coughing. Airborne detection of non-SARS-CoV-2 viruses was rare, suggesting that these viruses may be more difficult to detect in the air. Future studies should examine the importance of close contact and long-range transmission, and the cost-effectiveness of using air cleaners.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Development of an airborne sensor for reliable detection of volcanic ash(IEEE, 2016) Weingartner, Ernest; Jurányi, Zsofia; Egli, Daniel; Steigmeier, Peter; Burtscher, HeinzThis sensor detects volcanic ash particles and distinguishes them from cloud droplets. Operated on an airplane, this detector can quantify the exposure to hazardous refractory ash and the in-situ measurement is not biased by the presence of cloud particles. A volcanic eruption emits a significant amount of hazardous ash particles into the air. If the event is strong enough, the volcanic ash plume can reach high altitudes and can be a serious security risk for airplanes. We have developed a new prototype aerosol sensor for the reliable detection of volcanic ash. The envisaged application is the employment of this new technique on board of passenger aircraft. It allows in-situ monitoring of the airplane's exposure to volcanic ash. The challenge of this development is the requirement that the sensor can distinguish cloud droplets (or ice crystals) from the hazardous refractory ash particles. At aviation altitudes, water droplets and ice crystals are often present in the particle size region of the ash (1-20 micrometer) and their concentrations can reach the levels that are considered as the limits of the different volcanic ash contamination zones. Therefore, it is crucial that the sensor can differentiate between volcanic ash and water or ice particles. The sensor measures the scattered light intensities from individual particles outside of the airplane cabin through a glass window. The desired discrimination is achieved with two lasers operating at different wavelengths. Ash concentrations (in terms of number and mass) are derived, and the exposure of the airplane is recorded and transmitted in real time to the pilot. The volcanic ash detector was tested in the laboratory with various test aerosols and micrometer-sized water droplets. Then, ground-based outdoor measurements were conducted and the instrument response to mineral dust (a surrogate for volcanic ash) and natural cloud droplets (and ice crystals) was investigated. In a next step, this new technique will be tested in summer 2016 on-board of a research aircraft.04B - Beitrag KonferenzschriftPublikation Light scattering enhancement factors in the marine boundary layer (Mace Head, Ireland)(Wiley, 20.10.2010) Fierz‐Schmidhauser, Rahel; Zieger, Paul; Vaishya, Aditya; Monahan, Ciarán; Bialek, Jakub; O'Dowd, Collin D.; Jennings, Stephen G.; Baltensperger, Urs; Weingartner, ErnestDirect climate aerosol radiative forcing is influenced by the light scattering of atmospheric aerosols. The chemical composition, the size distribution, and the ambient relative humidity (RH) determine the amount of visible light scattered by aerosols. We measured the aerosol light scattering coefficients at RH varying from 30% to 90% of the marine atmosphere at the Mace Head Atmospheric Research Station on the west coast of Ireland. At this site, two major air mass types can be distinguished: clean marine and polluted air. In this paper, we present measurements of light scattering enhancement factors f(RH) = σsp(RH)/σsp(dry) from a 1 month field campaign (January–February 2009). At this site in winter, the mean f(RH = 85%) (standard deviation) for marine air masses at the wavelength of 550 nm was 2.22 (±0.17) and 1.77 (±0.31) for polluted air. Measured σsp(RH) and f(RH) agreed well with calculations from Mie theory using measurements of the size distribution and hygroscopic diameter growth factors as input. In addition, we investigated the RH influence on additional intensive optical properties: the backscatter fraction and the single scattering albedo. The backscatter fraction decreased by about 20%, and the single scattering albedo increased on average by 1%–5% at 85% RH compared to dry conditions.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Physical properties, chemical composition, and cloud forming potential of particulate emissions from a marine diesel engine at various load conditions(American Chemical Society, 19.04.2010) Petzold, Andreas; Weingartner, Ernest; Hasselbach, Jan; Lauer, Peter; Kurok, C.; Fleischer, Fritz01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Subarctic atmospheric aerosol composition. 3. Measured and modeled properties of cloud condensation nuclei(Wiley, 19.02.2010) Kammermann, Lukas; Gysel, Martin; Weingartner, Ernest; Herich, Hanna; Cziczo, Daniel J.; Holst, Thomas; Svenningsson, Birgitta; Arneth, Almut; Baltensperger, UrsAerosol particles can modify cloud properties by acting as cloud condensation nuclei (CCN). Predicting CCN properties is still a challenge and not properly incorporated in current climate models. Atmospheric particle number size distributions, hygroscopic growth factors, and polydisperse CCN number concentrations were measured at the remote subarctic Stordalen mire, 200 km north of the Arctic Circle in northern Sweden. The CCN number concentration was highly variable, largely driven by variations in the total number of sufficiently large particles, though the variability of chemical composition was increasingly important for decreasing supersaturation. The hygroscopicity of particles measured by a hygroscopicity tandem differential mobility analyzer (HTDMA) was in agreement with large critical diameters observed for CCN activation (κ ≈ 0.07–0.21 for D = 50–200 nm). Size distribution and time‐ and size‐resolved HTDMA data were used to predict CCN number concentrations. Agreement of predictions with measured CCN within ±11% was achieved using parameterized Köhler theory and assuming a surface tension of pure water. The sensitivity of CCN predictions to various simplifying assumptions was further explored: We found that (1) ignoring particle mixing state did not affect CCN predictions, (2) averaging the HTDMA data in time with retaining the size dependence did not introduce a substantial bias, while individual predictions became more uncertain, and (3) predictions involving the hygroscopicity parameter recommended in literature for continental sites (κ ≈ 0.3 ± 0.1) resulted in a significant prediction bias. Future modeling studies should therefore at least aim at using averaged, size‐resolved, site‐specific hygroscopicity or chemical composition data for predictions of CCN number concentrations.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation(Springer, 24.08.2011) Kirkby, Jasper; Curtius, Joachim; Almeida, João; Dunne, Eimear; Duplissy, Jonathan; Ehrhart, Sebastian; Franchin, Alessandro; Gagné, Stéphanie; Ickes, Luisa; Kürten, Andreas; Kupc, Agnieszka; Metzger, Axel; Riccobono, Francesco; Rondo, Linda; Schobesberger, Siegfried; Tsagkogeorgas, Georgios; Wimmer, Daniela; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; David, André; Dommen, Josef; Downard, Andrew; Ehn, Mikael; Flagan, Richard C.; Haider, Stefan; Hansel, Armin; Hauser, Daniel; Jud, Werner; Junninen, Heikki; Kreissl, Fabian; Kvashin, Alexander; Laaksonen, Ari; Lehtipalo, Katrianne; Lima, Jorge; Lovejoy, Edward R.; Makhmutov, Vladimir; Mathot, Serge; Mikkilä, Jyri; Minginette, Pierre; Mogo, Sandra; Nieminen, Tuomo; Onnela, Antti; Pereira, Paulo; Petäjä, Tuukka; Schnitzhofer, Ralf; Seinfeld, John H.; Sipilä, Mikko; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Vanhanen, Joonas; Viisanen, Yrjo; Vrtala, Aron; Wagner, Paul E.; Walther, Hansueli; Weingartner, Ernest; Wex, Heike; Winkler, Paul M.; Carslaw, Kenneth S.; Worsnop, Douglas R.; Baltensperger, Urs; Kulmala, MarkkuAtmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H2SO4–H2O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.01A - Beitrag in wissenschaftlicher Zeitschrift