Hochschule für Technik und Umwelt FHNW
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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 High order dynamic mode decomposition for mechanical vibrations and modal analysis(HAL, 2023) Tuor, Andreas; Canzani, Nico; Rüggeberg, Tobias; Gorenflo, Stefan; Simons, Gerd; Bättig, Bruno; Iseli, Daniel05 - Forschungs- oder ArbeitsberichtPublikation Development of a waveguide-based interferometer for the measurement of trace substances(Zenodo, 07.11.2023) Weingartner, Ernest; Bilal, Jonas; Steigmeier, Peter; Jundt, Gregor; Häusler, Samuel; Lenner, Miklós; Flöry, Nikolaus; Bittner, Matthias; Betschon, FelixPhotonic integration on a chip has the potential to develop new low-cost, high-performance sensing devices. A proof of concept of the sensing capabilities of a waveguide-based photothermal interferometer for the measurement of traces of light-absorbing substances (soot particles, gases) has been achieved. The measurement principle can also be extended to a wide range of other applications such as refractive index measurements, or vibration/distance sensors. A unique feature is that the waveguide technology allows for a passive operation of the interferometer, i.e., no quadrature point control is required.04B - Beitrag KonferenzschriftPublikation 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 Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation(Copernicus, 26.05.2010) Spracklen, Dominick V.; Carslaw, Kenneth S.; Merikanto, Joonas; Mann, Graham W.; Reddington, Carly L.; Pickering, S.; Ogren, John A.; Andrews, Elisabeth; Baltensperger, Urs; Weingartner, Ernest; Boy, Michael; Kulmala, Markku; Laakso, Lauri; Lihavainen, Heikki; Kivekäs, Niku; Komppula, Mika; Mihalopoulos, Ninolaos; Kouvarakis, Giorgos; Jennings, Stephen G.; O'Dowd, Collin D.; Birmili, Wolfram; Wiedensohler, Alfred; Weller, Rolf; Gras, John; Laj, Paolo; Sellegri, Karine; Bonn, Boris; Krejci, Radovan; Laaksonen, Ari; Hamed, Amar; Minikin, Andreas; Harrison, Roy Michael; Talbot, Robert; Sun, JunyingWe synthesised observations of total particle number (CN) concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300–2000 cm−3 in the marine boundary layer and free troposphere (FT) and 1000–10 000 cm−3 in the continental boundary layer (BL). Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2–10 greater than wintertime concentrations. We used these CN observations to evaluate primary and secondary sources of particle number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R2=0.46) but fail to explain the observed seasonal cycle (R2=0.1). The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=−88%) unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=−25%). Simulated CN concentrations in the continental BL were also biased low (NMB=−74%) unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J, proportional to gas-phase sulfuric acid concentration to the power one) or kinetic-type mechanism (J proportional to sulfuric acid to the power two) with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R2=0.3) than by increasing the number emission from primary anthropogenic sources (R2=0.18). The nucleation constants that resulted in best overall match between model and observed CN concentrations were consistent with values derived in previous studies from detailed case studies at individual sites. In our model, kinetic and activation-type nucleation parameterizations gave similar agreement with observed monthly mean CN concentrations.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation EUCAARI ion spectrometer measurements at 12 European sites – analysis of new particle formation events(Copernicus, 25.08.2010) Manninen, Hanna E.; Nieminen, Tuomo; Asmi, Eija; Gagné, Stéphanie; Häkkinen, Silja; Lehtipalo, Katrianne; Aalto, Pasi Pekka; Vana, Marko; Mirme, Aadu; Mirme, Sander; Hõrrak, Urmas; Plass-Dülmer, Christian; Stange, Gert; Kiss, Gyula; Hoffer, András; Törő, N.; Moerman, Marcel; Henzing, Bas; de Leeuw, Gerrit; Brinkenberg, Marcel; Kouvarakis, Giorgos N.; Bougiatioti, Aikaterini; Mihalopoulos, Nikolaos; O'Dowd, Colin D.; Ceburnis, Darius; Arneth, Almut; Svenningsson, Brigitta; Swietlicki, Erik; Tarozzi, Leone; Decesari, Stefano; Facchini, Maria Cristina; Birmili, Wolfram; Sonntag, André; Wiedensohler, Alfred; Boulon, Julien; Sellegri, Karine; Laj, Paolo; Gysel, Martin; Bukowiecki, Nicolas; Weingartner, Ernest; Wehrle, Günther; Laaksonen, Ari; Hamed, Amar; Joutsensaari, Jorma; Petäjä, Tuukka; Kerminen, Veli-Matti; Kulmala, MarkkuWe present comprehensive results on continuous atmospheric cluster and particle measurements in the size range ~1–42 nm within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) project. We focused on characterizing the spatial and temporal variation of new particle formation events and relevant particle formation parameters across Europe. Different types of air ion and cluster mobility spectrometers were deployed at 12 field sites across Europe from March 2008 to May 2009. The measurements were conducted in a wide variety of environments, including coastal and continental locations as well as sites at different altitudes (both in the boundary layer and the free troposphere). New particle formation events were detected at all of the 12 field sites during the year-long measurement period. From the data, nucleation and growth rates of newly formed particles were determined for each environment. In a case of parallel ion and neutral cluster measurements, we could also estimate the relative contribution of ion-induced and neutral nucleation to the total particle formation. The formation rates of charged particles at 2 nm accounted for 1–30% of the corresponding total particle formation rates. As a significant new result, we found out that the total particle formation rate varied much more between the different sites than the formation rate of charged particles. This work presents, so far, the most comprehensive effort to experimentally characterize nucleation and growth of atmospheric molecular clusters and nanoparticles at ground-based observation sites on a continental scale.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 Konferenzschrift