National Repository of Grey Literature 54 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Biomechanical aspects of the reconstruction of the acetabulum
Slávik, Ondrej ; Marcián, Petr (referee) ; Florian, Zdeněk (advisor)
The research part of bacelor’s thesis Biomechanical aspects of the reconstruction of the acetabulum is dealing with historical development and current methods of solving the issue of pathological hip joints in case when use of total endoprosthesis is not suitable, for example in children. Also the anatomical view, related to the given problem situation, is outlined and the most significant disorders of the hip joint, which are connected with these cases, are characterized. In the practical part of this work, there are results of the analysis model between pathological and physiological hips analyzed and qualitatively compared, followed by the solution of the concact forces in these two situations.
Mutual interaction of multiple cracks growing in the particulate composite with brittle matrix under conditions of sub-critical crack growth
Slávik, Ondrej ; Ševeček, Oldřich (referee) ; Majer, Zdeněk (advisor)
In the first part of the submitted diploma thesis, the knowledge in the sphere of the fracture mechanics, related to the practice part of this thesis are summarized. In that the 2D parametrical numerical model of the particle composite with multiple cracks was created, using the finite elements method. Thanks to this model it is possible to find specific configurations which are showing the existance of multiple mutual interactions between these cracks, just by simple manipulation of the input data. In the calculations the influence of the residual stresses was considered which are formed during production of the material. The effect of the subcritical crack growth was taken into account as well in this thesis.
Fatigue Crack Propagation under Combined Load in Selected Polymer and Metal Materials
Slávik, Ondrej ; Klusák, Jan (referee) ; Padovec,, Zdeněk (referee) ; Náhlík, Luboš (advisor)
Material fatigue plays key role in terms of lifetimes of many service parts. Study of fatigue behavior of materials is ongoing from the previous century. To a large degree, the focus is put on studies of fatigue crack growth under uniaxial loading, or the so-called opening mode crack growth. However, in practice there are multiple cases of multiaxially loaded service parts, in which cracks loaded under mixed-mode loading conditions may be present. There is currently not enough knowledge with regards to this topic. This thesis is focused on some of the aspects of fatigue crack growth under combined loading. The aim is to find appropriate experimental specimens for studies regarding these issues and with their help to acquire necessary experimental data. Obtained results were used for simplification of residual fatigue lifetime estimation of parts made of polymer and metal materials. In the thesis it is also noticed about the differences in fatigue fractures between polymer and metal materials loaded by combination of tension and shear loading. These results contribute to better understanding of the processes of fatigue fractures of parts loaded by combined loading. Therefore, the submitted thesis is focused on the studies of fatigue behavior of metal and polymer materials under multiaxial loading.
Trophic structure of fish communities in anthropogenically impacted rivers
Dostál, David ; Horká, Petra (advisor) ; Slavík, Ondřej (referee)
The aim of this work was to describe trophic relationships in fish communities in an anthropogenically influenced environment. In them, non-specialized, so-called eurytopic fish species predominate over rheophilic fish, which have a more complex life cycle, greater demands on habitat, food resources, or spawning substrate. They are less able to adapt to human-induced changes. On the other hand, eurytopic species have very little requirements, so they are able to adapt to environmental changes without major problems. With this work, I wanted to verify the assumption that eurytopic fish species will have a wider trophic niche and a better trophic position in such an environment than rheophilic species. All this using the analysis of stable isotopes 15 N and 13 C with the contribution of the SIBER and tRophic position computing program. Key words: stable isotopes, trophic niche and position, riverine systems, freshwater fish
Seasonal variation of activity and pathogen prevalence in populations of the spiny-cheek crayfish
Matasová, Klára ; Petrusek, Adam (advisor) ; Slavík, Ondřej (referee)
The most widespread of invasive crayfish in the Czech Republic is the spiny-cheek crayfish (Orconectes limosus). It is a major disease carrier of crayfish plague, caused by the pathogen Aphanomyces astaci. The infection is lethal to European native species of crayfish. Transmission of this disease is usually associated with the spread of crayfish, which is dependent on their movement. The main aim of this work was to evaluate the differences in crayfish migratory activity in the Pšovka brook among seasons, and assess the factors that may affect it, by the use of radiotelemetry and trapping. We tested the hypothesis that crayfish use brook in the period from spring to autumn and then return back into a pond to overwinter. Furthermore, we evaluated how far from the pond crayfish migrate, and whether there is any relationship between migration and the season or water temperature. The results demonstrate that the activity varies among seasons (being strongly affected by breeding season) but in most studied periods did not significantly depend on water temperature. According to our monitoring, the spiny-cheek crayfish does not spread substantially to upstream parts of the Pšovka. Seasonal migration between the pond and the brook was monitored using two-way flow-through traps installed at the mouth of...
Spatial distribution of the European catfish Silurus glanis influenced by familiarity
Fořt, Martin ; Slavík, Ondřej (advisor) ; Kozák, Pavel (referee)
One of the key elements of animal social behaviour is the recognition of individuals on the basis of previous experience. This relationship is called familiarity and affects individual's behaviour. We know many examples of familiarity-based behaviour among fish. Many results show that familiarity is advantageous. Familiar individuals are less aggressive, forage more, make more cohesive shoals and grow faster. We tested the influence of the familiarity on the spatial distribution of juvenile wels catfish Silurus glanis from two unfamiliar groups, which were held in separate tanks. In a laboratory experiment was the spatial distribution of individuals monitored in the artificial stream by using passive integrated transponders. Shelters, which were occupied by individuals, were placed in the stream. Two groups of fish were subsequently added into the experiment under conditions of limited or unlimited shelters. These groups came from the same tank (so they were familiar) or from different tanks (so they were unfamiliar). 1080 individuals were used in this experiment and over three million individual fish positions were recorded. We discovered changing levels of activity under different conditions. When we compared activity of original and additional individuals, we measured higher level of activity in...
Within-group fish behaviour: effect of common experience
Fořt, Martin ; Slavík, Ondřej (advisor) ; Frouzová, Jaroslava (referee)
Recently, behavioral studies focusing on social relationships of fish in groups became popular. Fish are able individually recognize conspecifics or even heterospecifics. This ability allows distinguishing among individuals in and between groups and shows that fish prefer associating with familiar or kin individuals. An interaction with kin individuals is called condition-dependent recognition, whilst relationship based on previous experience is called condition independent recognition or familiarity. Both of these interactions can bring the participants some advantages, such as better protection from predators, foraging benefits, lower aggression levels, etc.
Age structure and growth of wild brown trout in relation to population density and habitat quality
Závorka, Libor ; Slavík, Ondřej (advisor) ; Matěna, Josef (referee) ; Reichard, Martin (referee)
Brown trout Salmo trutta L. is a fish species with high socio-economic value, which is favourable among anglers and a successful invader worldwide. The aim of this thesis is to explore environmental factors affecting body growth and survival of brown trout with emphasis on density dependent selection in juvenile life stages. This thesis is specifically focused on: (1) effect of population density on growth and survival with respect to a dynamic of a local group of individuals (papers I and II); (2) effect of inter-individual differences in behaviour on the relationship between individuals life-history traits and available resources (papers III and IV); (3) link between demo-genetic structure of population and growth and mortality rates of individuals (papers V, VI and VII). Datasets for this thesis were collected during a long-term mark-recapture study on wild brown trout population (2005-2011) in the catchment of the Otava River in Šumava National Park (Czech Republic) and a set of field and laboratory studies conducted on wild populations in streams on west coast of Sweden. In accordance with some previous studies, this thesis showed that growth of juvenile brown trout is negatively affected by population density. Nonetheless, this thesis reveals that the negative effect of density dependent...

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31 Slavík, Ondřej
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