National Repository of Grey Literature 28 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Study of size-resolved atmospheric aerosol using cascade impactors
Kozáková, Jana ; Schwarz, Jaroslav (advisor) ; Vojtíšek, Michal (referee) ; Krejci, Radovan (referee)
This dissertation includes two main research projects: 1) the investigation of the intermodal fraction and 2) the influence of regional air pollution transport on Ostrava. Introduction and aim of the first project. Fine and coarse particulate matter (PM) of atmospheric aerosol are considered as separate pollutants and overlap in the particle size range of about 1 - 2.5 μm (aerodynamic diameter dae; PM1-2.5) which represents the intermodal fraction. Sources of both fine and coarse fractions contribute to PM1-2.5 to different extents due to changing meteorological and spatial conditions. Therefore, there is an ongoing discussion as to whether PM1 should be included for monitoring as an additional fine particulate pollutant by the ambient air quality standard. The intrusion of the one fraction to the other one can lead to some inaccuracies in the source apportionment, epidemiological and exposure studies. The aim of the first project was to examine the associations between PM1-2.5 and the coarse (PM2.5-10 or PM>2.5)/fine (PM1) fraction under different meteorological conditions at various sites in the Czech Republic during winter and summer seasons. Introduction and aim of the second project. The EU air quality standards have been frequently exceeded in one of the European air pollution hot spots:...
Study of aerosol properties with high time resolution
Kubelová, Lucie ; Ždímal, Vladimír (advisor) ; Hovorka, Jan (referee) ; Vojtíšek, Michal (referee)
This thesis focuses on physical and chemical characteristics of atmospheric aerosol measured with high time resolution. Size distribution, chemical composition, and volatility of submicron particles were studied in relation to meteorological conditions and other factors. To reach higher variability in ambient conditions, we considered atmospheric aerosol during two seasons of the year (summer and winter) and at two different locations (suburban site Prague Suchdol and rural site Košetice). Measurement during two different seasons enabled us to better distinguish the influence of seasonal sources such as domestic heating in winter and increased biogenic emissions in summer. Also, seasonal differences in meteorological conditions mainly in case of temperature, humidity, and solar radiation were shown to play a role in aerosol characteristics. A comparison of aerosol properties at two different measurement sites, namely a rural and suburban, enabled us to better characterize the role of background aerosol and the influence of the city. Furthermore, a transformation of aerosol particles entering indoors from outdoors was also studied within this thesis. The influence of indoor/outdoor temperature and humidity gradient as well as presence of new particle formation events on the indoor/outdoor ratio was...
Contactless Measurement of Combustion Engine Emissions: First Experience with the Detection of High Particle Emitters.
Vojtíšek, M. ; Pechout, M. ; Skácel, J. ; Beránek, V. ; Ondráček, Jakub
A roadside measurement of particulate matter concentrations with two fast-response instruments, an electric mobility particle sizer and a photoacoustic sensor, with parallel CO2 measurement used to calculate emissions per kg of fuel, was conducted as a preliminary assessment of suitability of the method to identify high particle emitters.
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Characterization of Aerosol Generated by Laser Ablation for Inductively Coupled Plasma Mass Spectroscopy.
Holá, M. ; Ondráček, Jakub ; Nováková, H. ; Vojtíšek, M. ; Šperka, J. ; Havlíček, M. ; Kanický, V.
Laser ablation (LA), together with inductively coupled plasma mass spectrometry (ICP-MS) as a detection system, has become a routine method for the direct analysis of various solid samples. The product of laser ablation contains a mixture of vapour, droplets and solid particles. All components are finally transported to a plasma by a carrier gas in form of dry aerosol that includes mainly agglomerates of primary nanoparticles. Dry aerosol can be studied by different offline or online techniques. In general, characterisation of aerosols by their particle size distribution (PSD) represents indispensable tool for fundamental studies of the interaction of laser radiation with various materials. Many works have studied PSD of dry aerosol for different samples, and different ablation conditions (Hola et al., 2010).The laser ablation was performed with nanosecond laser (193 nm) on glass and steel samples using various ablation conditions (spot size, ablation mode, repetition rate, fluence). The aerosol characterization was made first by online PSD monitoring using Engine Exhaust Particle Sizer (EEPS) simultaneously with laser ablation - ICP-MS analysis. Second, the structure of the laser-generated particles was studied off-line using scanning electron microscopy (SEM) and atomic force microscopy (AFM).
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A detailed study on aerosol particle size distribution in indoor and outdoor environments with attention to ammonium nitrate transormations
Talbot, Nicholas Philip ; Ždímal, Vladimír (advisor) ; Hovorka, Jan (referee) ; Vojtíšek, Michal (referee)
Due to its prevalence over large, densely populated areas, ammonium nitrate is an important chemical species in aerosol research. However, due to its volatility at ambient temperatures and over low temperature gradients, ammonium nitrate can be a difficult species to accurately measure. The volatility of ammonium nitrate is known to be dependent on temperature, relative humidity, the internal mixing state of the particle, and availability of the precursor gas constituents. The particle's physical state affects the equilibrium constant value of the ammonium nitrate - nitric acid / ammonia exchange and helps determine the dissociation rate. For indoor aerosol research, the outdoor originating aerosol particles' exposure to the new physical conditions indoors, such as changes in temperature, humidity, and particle-surface reactions within the microenvironment all accelerate ammonium nitrate dissociation. This increased rate of partitioning can generate artifacts on datasets, increase indoor particle formation, and accelerate the corrosion of cultural antiquities through acidification. The magnitude of these impacts is uncertain due to the current lack of knowledge on particle transformation processes when outdoor originating particles migrate indoors. To address this gap in knowledge, this thesis...

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See also: similar author names
3 Vojtíšek, Martin
3 Vojtíšek, Maximilian
2 Vojtíšek, Miloš
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