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Wind tunnel study of dispersion in different urban area configurations
Chaloupecká, Hana ; Jurčáková, Klára ; Kellnerová, Radka ; Kukačka, Libor ; Jaňour, Zbyněk
The object of this study is modelling of pollution dispersion in a wind tunnel. We’ve used the inverse method of modelling to this.That means a given location of detector of pollution and a net of points where we placed one by one a point source. We’ve studied this probem for different set-ups of buildings and approach flow directions. A sensitivity of concentration diffusion upon on the type of set-up of buildings and approach flow direction has been demonstrated from the results of experiment. The best se-up of buildings due to the measurement of concentration in two fixed points has been found.
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Ecology of Veliidae and Mesoveliidae (Heteroptera: Gerromorpha)in Central Europe
DITRICH, Tomáš
Ecology of Veliidae and Mesoveliidae (Hemiptera: Heteroptera: Gerromorpha) was studied in selected European species. The research of these non-gerrid semiaquatic bugs was especially focused on voltinism, overwintering with physiological consequences and wing polymorphism with dispersal pattern. Hypotheses based on data from field surveys were tested by laboratory, mesocosm and field experiments. New data on life history traits and their ecophysiological consequences are discussed in seven original research papers (four published journal papers, two submitted papers and one communication in conference proceedings), creating core of this thesis.
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Individual marking of small insects and its usage in describing societies and migration of semiaquatic bugs (Heteroptera: Gerromorpha) in lentic and lotic habitats of Novohradské Mountains.
VOJÍŘOVÁ, Eva
Experiments based on the method of mark-recapture can be used for estimation of the abundance of natural populations, for monitoring dispersion of groups or individual specimens within a population using group or individual marking. Semiaquatic bugs (Heteroptera: Gerromorpha) were marked and recaptured many times in the field during research, individual marking was much less used since marking of small insects is difficult. The aim of this work is to develop a method of individual marking of semiaquatic bugs so that it would meet conditions such as durability, legibility and non affecting health of the marked specimen. Semiaquatic bugs of Aquarius paludum, Gerris lacustris, Limnoporus rufoscutellatus (Gerridae) and Velia caprai (Veliidae) species were selected as experimental organisms. Partial aims of this thesis were to try using this method to describe the abundance of the monitored population and to monitor dispersion of the selected species, both at lotic (V. caprai) and lentic habitats (water striders, family Gerridae). A new method of individual marking of semiaquatic bugs was developed on the basis of modifications of the commonly used methods. After a series of tests and in-field research, this method proved to be suitable as it met the essential conditions for marking insects. The abundance of the monitored population was estimated and dispersion of the selected species (V. caprai) in running water was described by using this method. The partial aims of this thesis were met, too. It was confirmed that individuals of the V. caprai species move between the monitored areas along the water course. This inclination to move is greater than tendency to remain in the place of release. The gained data also show conclusively higher rate of movement of V. caprai specimens in the upstream direction, compared to the downstream. The tendency of V. caprai to travel larger distance upstream than downstream, is significant too. No statistically relevant difference in either direction of the water course (up or down) in the surpassed altitude difference was confirmed. The differences in the monitored phenomena between the sexes and generations were compared as well. The differences, however, were not significant. A movement of the adults of the water cricket Velia caprai thus can be characterized as an upstream migration, common in insects of lotic habtitats. A part of the study taking place in still waters showed, that G. lacustris specimens move on the surface of the pond, but not to a larger degree than they remain in place. On the other hand, A. paludum specimens were proved to move away from the place of release rather than remaining in that place. These also overcome greater distance than G. lacustris specimens.
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Analysis of classical and spectral finite element spatial discretization in one-dimensional elastic wave propagation
Kolman, Radek ; Plešek, Jiří ; Okrouhlík, Miloslav ; Gabriel, Dušan
The spatial discretization of continuum by finite element method introduces the dispersion error to numerical solutions of stress wave propagation. For higher order finite elements there are the optical modes in the spectrum resulting in spurious oscillations of stress and velocity distributions near the sharp wavefront. Spectral finite elements are of h-type finite element, where nodes have special positions along the elements corresponding to the numerical quadrature schemes, but the displacements along element are approximated by Lagrangian interpolation polynomials. In this paper, the classical and Legendre and Chebyshev spectral finite elements are tested in the one-dimensional wave propagation in an elastic bar.
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Modelling of toxic gases substituents on the model of the Old Town Square in Prague
Bezpalcová, Klára
The model of the place and its vicinity was manufactured, an atmospheric boundary layer in the appropriate scale (i.e. in scale 1:270, in which the model was manufactured) was created in the wind tunnel, and the climatology of the location was study in order to select prevailing wind directions in the frame of the experiment preparation. Also a flow visualization using a smoke generator and laser sheet was conducted. The concentration of the toxic gas substituents (propan and pentyl acetate) were measured in the location of the Old Town Square in Pargue for 4 different source locations (corner of the Pařížské street, Hus monument, City Hall tower a passage by U Prince) and for 5 prevailing wind directions (NW, WNW, W, WSW, SW).
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