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Transition metal oxides for chemical sensors
Volfová, Lenka ; Tyrpekl, Václav (advisor) ; Zelinger, Zdeněk (referee) ; Myslík, Vladimír (referee)
Outdoor air pollution is one of the main environmental problems today. Its monitoring is, among other things, given by the European Union directive (2008/50/EC) on air quality and places high demands on the quantity and reliability of sensors deployed in our immediate surroundings. In order to continuously monitor large number of habitats, it is necessary to develop simple and inexpensive types of sensors. Figure 1 shows an example of such a sensor. The topic of the dissertation is the preparation by physical methods and the study of the surfaces of thin oxide layers as an active medium for the above-mentioned applications. The thesis investigates the possibility of materials preparation by pulsed laser deposition, discharge in a hollow cathode and magnetron sputtering thin film materials for chemiresistor sensors based on copper and tungsten oxides, luminescent Eu doped ZnO layers and resonant so-called QCM, where a quartz resonator was covered with a layer of black aluminium showing a large specific surface in order to increase the sensitivity of these types of sensors. Since the state and properties of the surface are crucial for the function of these types of sensors, an integral and important part of the work is the characterization of the structural properties of the prepared layers,...
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Sudden release of toxic gas in built-up environment
Chaloupecká, Hana ; Jaňour, Zbyněk (advisor) ; Zelinger, Zdeněk (referee) ; Efthimiou, George (referee)
The dissertation thesis deals with short-term gas releases (puffs) in an urban canopy studied utilizing wind-tunnel modelling. The urban canopy was composed of buildings with pitched roofs organised into closed courtyards. Into it, a ground-level point gas source was placed. The first part of the thesis is focused on specific definitions of puff characteristics. New definitions of puff arrival and departure times are presented. Various definitions of puff arrival time were applied on the same datasets and the results were compared. Moreover, it was studied how slight changes in determination of puff departure time can affect its values and other derived puff characteristics. The second part of the thesis is focused on modelling of probability density functions of puff characteristics with knowledge of sampling positions towards the gas source and mean values of concentrations valid for long-term gas sources. The found equations will be utilized in an operational model. The outputs in the form of the probability density functions of puff characteristics distinguish my model from the usually utilized operational models, in which only the ensemble-averaged puff outline and concentration field can be predicted.
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Estimation of the distribution of groundconcentrations from point sources in complex terrain-by simulation in the wind-tunnel
Plášilová, Eva ; Zelinger, Zdeněk (advisor) ; Keder, Josef (referee)
Estimation of the distribution of ground concentrations from point sources in complex terrain - by simulation in the wind-tunnel Eva Plasilova 2009 - Charles University in Prague Faculty of Mathematics and Physics Department of Meteorology and Environment Protection V Holesovickach 2 18000 PrahaS Academy of Sciences of the Czech Republic Institute of thermomechanics, v. v. i. Dolejskova 5 18200 PrahaS Abstract of rigorousthesis Task of this work has been to monitor the behaviour and to estimate the concentration of pollutants in atmosphere. To-this purpose was selected as a model town Jablonne nad Orlici and as a technical solution to the problem was physical modeling in the wind-tunnel (in scale 1:1000). First of all, I define important terms (mainly turbulence, atmospheric boundary layer), equations: that describe atmospheric motions, and give account of wind-tunnel and methods of measurement. I estimated the concentrations above the ground qualitatively (vissually - using laser knife) and quantitatively (using the infrared analyzer IREX and the flame ionization detector FID). . High imission load in a densely settled part of the town Jablonne nad Orlici was demonstrated. From the theoretical point of view I tested the influence of the complex terrain and of the source-parameters on the dispersion of...
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Sudden release of toxic gas in built-up environment
Chaloupecká, Hana ; Jaňour, Zbyněk (advisor) ; Zelinger, Zdeněk (referee) ; Efthimiou, George (referee)
The dissertation thesis deals with short-term gas releases (puffs) in an urban canopy studied utilizing wind-tunnel modelling. The urban canopy was composed of buildings with pitched roofs organised into closed courtyards. Into it, a ground-level point gas source was placed. The first part of the thesis is focused on specific definitions of puff characteristics. New definitions of puff arrival and departure times are presented. Various definitions of puff arrival time were applied on the same datasets and the results were compared. Moreover, it was studied how slight changes in determination of puff departure time can affect its values and other derived puff characteristics. The second part of the thesis is focused on modelling of probability density functions of puff characteristics with knowledge of sampling positions towards the gas source and mean values of concentrations valid for long-term gas sources. The found equations will be utilized in an operational model. The outputs in the form of the probability density functions of puff characteristics distinguish my model from the usually utilized operational models, in which only the ensemble-averaged puff outline and concentration field can be predicted.
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