Auflistung nach Autor:in "Müller, Thomas"

Gerade angezeigt 1 - 9 von 9

A dual-wavelength photothermal aerosol absorption monitor. Design, calibration and performance
(Copernicus, 2022) Drinovec, Luka; Jagodič, Uroš; Pirker, Luka; Škarabot, Miha; Kurtjak, Mario; Vidović, Kristijan; Ferrero, Luca; Visser, Bradley; Röhrbein, Jannis; Weingartner, Ernest; Kalbermatter, Daniel M.; Vasilatou, Konstantina; Bühlmann, Tobias; Pascale, Celine; Müller, Thomas; Wiedensohler, Alfred; Močnik, Griša
There exists a lack of aerosol absorption measurement techniques with low uncertainties and without artefacts. We have developed the two-wavelength Photothermal Aerosol Absorption Monitor (PTAAM-2λ), which measures the aerosol absorption coefficient at 532 and 1064 nm. Here we describe its design, calibration and mode of operation and evaluate its applicability, limits and uncertainties. The 532 nm channel was calibrated with ∼ 1 µmol mol−1 NO2, whereas the 1064 nm channel was calibrated using measured size distribution spectra of nigrosin particles and a Mie calculation. Since the aerosolized nigrosin used for calibration was dry, we determined the imaginary part of the refractive index of nigrosin from the absorbance measurements on solid thin film samples. The obtained refractive index differed considerably from the one determined using aqueous nigrosin solution. PTAAM-2λ has no scattering artefact and features very low uncertainties: 4 % and 6 % for the absorption coefficient at 532 and 1064 nm, respectively, and 9 % for the absorption Ångström exponent. The artefact-free nature of the measurement method allowed us to investigate the artefacts of filter photometers. Both the Aethalometer AE33 and CLAP suffer from cross sensitivity to scattering – this scattering artefact is most pronounced for particles smaller than 70 nm. We observed a strong dependence of the filter multiple scattering parameter on the particle size in the 100–500 nm range. The results from the winter ambient campaign in Ljubljana showed similar multiple scattering parameter values for ambient aerosols and laboratory experiments. The spectral dependence of this parameter resulted in AE33 reporting the absorption Ångström exponent for different soot samples with values biased 0.23–0.35 higher than the PTAAM-2λ measurement. Photothermal interferometry is a promising method for reference aerosol absorption measurements.
01A - Beitrag in wissenschaftlicher Zeitschrift
A European aerosol phenomenology-5. Climatology of black carbon optical properties at 9 regional background sites across Europe
(Elsevier, 2016) Zanatta, Marco; Gysel, Martin; Bukowiecki, Nicolas; Müller, Thomas; Weingartner, Ernest; Areskoug, Hans; Fiebig, Markus; Yttri, Karl Espen; Mihalopoulos, Nikolaos; Kouvarakis, Giorgos; Beddows, David; Harrison, Roy; Cavalli, Fabrizia; Putaud, Jean; Spindler, Gerald; Wiedensohler, Alfred; Alastuey, Andrés; Pandolfi, Marco; Sellegri, Karine; Swietlicki, Erik; Jaffrezo, Jean-Luc; Baltensperger, Urs; Laj, Paolo
01A - Beitrag in wissenschaftlicher Zeitschrift
Characterization and intercomparison of aerosol absorption photometers. result of two intercomparison workshops
(Copernicus, 2011) Müller, Thomas; Henzing, Bas; de Leeuw, Gerrit; Wiedensohler, Alfred; Alastuey, Andrés; Angelov, H.; Bizjak, Milan; Collaud Coen, Martine; Engström, J. E.; Gruening, Carsten; Hillamo, Risto; Hoffer, András; Imre, Kornélia; Ivanow, Petko; Jennings, Stephen G.; Sun, Junying; Kalivitis, Nikos; Karlsson, Hanna; Komppula, Mikka; Laj, Paolo; Li, S.-M.; Lunder, Chris; Marinoni, Angela; Martins dos Santos, Sebastiao; Moerman, Marcel; Nowak, Andreas; Ogren, John A.; Petzold, Andreas; Pichon, Jean Marc; Rodriquez, Sergio; Sharma, Sangeeta; Sheridan, Patrick J.; Teinilä, Kimmo; Tuch, Thomas; Viana, Mar; Virkkula, Aki; Weingartner, Ernest; Wilhelm, R.; Wang, Yaqiang
Absorption photometers for real time application have been available since the 1980s, but the use of filter-based instruments to derive information on aerosol properties (absorption coefficient and black carbon, BC) is still a matter of debate. Several workshops have been conducted to investigate the performance of individual instruments over the intervening years. Two workshops with large sets of aerosol absorption photometers were conducted in 2005 and 2007. The data from these instruments were corrected using existing methods before further analysis. The inter-comparison shows a large variation between the responses to absorbing aerosol particles for different types of instruments. The unit to unit variability between instruments can be up to 30% for Particle Soot Absorption Photometers (PSAPs) and Aethalometers. Multi Angle Absorption Photometers (MAAPs) showed a variability of less than 5%. Reasons for the high variability were identified to be variations in sample flow and spot size. It was observed that different flow rates influence system performance with respect to response to absorption and instrumental noise. Measurements with non absorbing particles showed that the current corrections of a cross sensitivity to particle scattering are not sufficient. Remaining cross sensitivities were found to be a function of the total particle load on the filter. The large variation between the response to absorbing aerosol particles for different types of instruments indicates that current correction functions for absorption photometers are not adequate.
01A - Beitrag in wissenschaftlicher Zeitschrift
Framing. Wer das grosse Ganze sieht, trifft bessere Entscheidungen
(Verlag Vertieftes Lernen, 2019) Müller, Thomas; Mühlhäuser, Andreas; Hugentobler, Walter; Köhle, Ivan; Legena, Valeria
Framing ist grundsätzlich eine nützliche Denkstrategie. Es hilft uns dabei, Informationen zu verorten und rasche Urteile und Entscheidungen zu fällen. In welchem Rahmen (Frame) uns diese Informationen aber präsentiert werden, hat Auswirkungen auf unsere Entscheidungen. Konkret können Frames dazu führen, dass wir uns von nicht rationalen Kriterien in unserer Entscheidungsfindung leiten lassen. Ein wirksames Gegenmittel gegen irrationale Frames ist, den Entscheidungsrahmen grösser zu machen.
04A - Beitrag Sammelband
Influence of water uptake on the aerosol particle light scattering coefficients of the Central European aerosol
(Stockholm University Press, 2014) Zieger, Paul; Fierz-Schmidhauser, Rahel; Poulain, Laurent; Müller, Thomas; Birmili, Wolfram; Spindler, Gerald; Wiedensohler, Alfred; Baltensperger, Urs; Weingartner, Ernest
01A - Beitrag in wissenschaftlicher Zeitschrift
Optimizing Internal Financial Reporting
(2018) Krings, Ulrich; Müller, Thomas; Kustner, Clemens; Baumann, Michael
Corporate reporting undoubtedly plays a major part in supporting decision-making by company management. In addition to contents of the reports, the way the reports are distributed and pre-sented are also of great importance. Based on the results of a survey done with the 50 CFOs of mid-sized are Swiss companies, this paper will identify five steps for optimizing the presentation of information in such reports. This not only involves increasing the effectiveness of the content, but also increasing of the reporting processes.
04B - Beitrag Konferenzschrift
Reinigungseffektivität und Kavitationsrauschpegel bei Ultraschall-unterstützter wässriger Reinigung von Medizinprodukten
(2012) Jung, Christiane; Budesa, Boris; Fässler, Fabian; Uehlinger, Robert; Müller, Thomas; Schaffner, Patrik; Bläsi, Simon; de Wild, Michael
04B - Beitrag Konferenzschrift
Welche sozialen Faktoren beeinflussen den Konsum?
(Pabst Science Publishers, 2020) Krebs, Marcel; Schmid, Otto; Müller, Thomas
04A - Beitrag Sammelband
Welches Modell steht hinter dem bio-psycho-sozialen Ansatz?
(Pabst Science Publishers, 2020) Krebs, Marcel; Schmid, Otto; Müller, Thomas
04A - Beitrag Sammelband