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Thermoacoustic measurement of ultrasonic power
Kučera, Václav ; Čížek, Martin (referee) ; Rozman, Jiří (advisor)
The thesis deals with ultrasound intensity and power measuring methods of the medical diagnostic systems, especially with thermoacoustic method. Then the concept of thermoacoustic sensor is processed and it is checked by comparison with the power of ultrasound system measured by the hydrophone in ultrasonic measuring tank. In the leading chapter basic parameters of general ultrasonic field are described. Next part deals with particular ultrasound intensity and power measuring methods. The last part deals with projecting of the thermoacoustic sensor, measuring with this sensor, measuring with hydrophone and comparison of this measurements.
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The study of the influence of process parameters on the roughness of the cut for flame laser cutting of stainless steel
Kučera, Václav ; Hála, Michal (referee) ; Mrňa, Libor (advisor)
Thesis presents a study of the influence of process parameters on the roughness of the cut surface. The test material is 1.4301, namely austenitic stainless steel. When a parameter is the surface roughness not change too much. In some samples there were defects in the form of cutting burrs. The graphs below show the estimated minimum change one parameter (the lowest point of the curve). As the most important parameter from a technological point of view, cutting speed, constitutes a major cost item compared to the auxiliary gas and power. For samples with a thickness of 2 mm and 3 mm has been achieved good results with decrease in the cutting rate of 30% percent, although when cutting the samples with a default rate was almost identical results. For samples with a thickness of 3 mm the best results were achieved by increasing the speed by 30 %, decrease the rate should be compared with the economy of the process to reduce surface roughness. For changes in the gas pressure was achieved the best values at a pressure increase of 30 %. When you change the performance of the best results are achieved by setting 100–90 % capacity.
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Deep learning for the solution of differential equations
Vais, Matěj ; Congreve, Scott (advisor) ; Kučera, Václav (referee)
Neural networks are becoming an ever more prominent method in the field of differen- tial equations. Their use is embodied in the concept of physics-informed neural network (PINN), which combines a traditional deep neural network with the underlying laws of physics described by PDEs. We investigate the abilities of this relatively novel approach on thee diverse examples in order to give a good overview of its advantages and issues. Every problem is also solved via the finite element method, which serves as a reference. In addition to that, we propose the usage of pre-training, which is already present in other scientific areas. If we initialize the process of solving of one equation with a solution to a similar problem, in some settings, we were able to significantly reduce computation time, which is major drawback of PINNs. 1
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Comparison of direct regularization methods based on least squares for problems corrupted by noise
Cepko, Tomáš ; Hnětynková, Iveta (advisor) ; Kučera, Václav (referee)
In this thesis we are going to deal with the inverse linear approximation problem Ax ≈ b, where our goal is to find the best approximation x of the unknown exact solution. We are going to especially focus on the so-called rank-deficient and ill-posed problems, which are very ill-conditioned and sensitive to possible random noise present in b. To solve these problems, we must use regularization methods, which suppress this sensitivity. The main goal of this thesis is to get a comprehensive overview of direct methods T-SVD, T- TLS and Tikhonov regularization, and analyse their close connection with classical least squares methods. One possible approach is to formulate these regularization methods as so-called filtering. In this way we implement them for numerical experiments. This thesis will also include a numerical comparision of these methods for selected problems from the Regularization Toolbox and in the application problem of image reconstruction. 1
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Parallel time integration for ordinary differential equations
Záboj, Petr ; Kučera, Václav (advisor) ; Dolejší, Vít (referee)
This thesis is about the problem of parallel-in-time integration methods. The main bulk of this thesis consists of the Parareal algorithm, which is one of the most widely used and studied parallel-in-time integration methods. We focus on the derivation of the Parareal algorithm using single-step integration methods and the multiple shoot- ing method. Finally, the properties of this algorithm are demonstrated with numerical experiments. 1
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Influence of feeding management on intensive breeding of pikeperch (Sander lucoperca)
KUČERA, Václav
This thesis is aimed on problematics of intensive pikeperch aquaculture and the influence of the feeding by different types of pellets and also different frequencies of feeding during the day. Whole thesis consists of two separate experiments. In the first experiment I tried to evaluate the influence of sinking and floating type of pellets on the growth abilities and production markers of juvenile pikeperch. First experiment was stocked with 8000 pcs of juvenile pikeperch (average weight 21,38g). These fish were kept in controlled conditions for 16 weeks (average temperature of 21,37 ? 0,66 °C (7:00) and 20,77 ? 0,55 °C (15:00), average dissolved oxygen levels of 127,43 ? 2,37 % (7:00) and 117,03 ? 1,14% (15:00) °C, 120 % and initial biomass of 13,42 kg/m?). These fish were fed by belt feeders two types of pellets (floating Skretting Europa and sinking Biomar Effico Sigma) with the same nutrient composition. After 16 weeks all the production markers (SGR, FCR, WG, TL, CF and survival) were examined. Almost all the parameters showed the statistically significant difference in favor of the sinking pellets. Although growth heterogenity turned out to be lower in the group fed by floating pellets. In the second experiment 600 individuals of juvenile pikeperch with average weight of 37,49 g were stocked in tanks. These fish were kept in controlled conditions for 6 weeks (average temperature of 21,37 ? 0,66 °C (7:00) and 20,96 ? 0,66 °C (15:00), average dissolved oxygen levels of 127,43 ? 2,37 % (7:00) and 117,03 ? 1,14 % (15:00) with initial biomass of 13,35 kg/m?). These fish were fed by automatic feeder Imetronic Self Feeder in 3 different frequencies a day (3,6 or 12 batches). Pellets Skretting Europa- 15F were used in this experiment. After 6 weeks of rearing production markers were examined. Growth heterogenity, somatic indexes, and fin erosion were also examined. Also, blood samples were taken. After data analysis no statistically significant difference was found among the production markers in all three groups. Growth heterogenity was proven to be the lowest in the group fed 3x a day and highest in the group fed 12x a day. Organosomatic indexes showed statistically significant difference of HSI (hepatosomatic index). Highest index was observed in group fed 3x a day. During the analysis of the data from biochemical analysis increased levels of albumins and tryglicerids were observed especially in the group fed 12x a day. Simultaneously, statistically significant differences among the amonia levels (lowest concentration in the group fed 3x a day and highest in group fed 12x a day) and glucose (lowest concentration in the group fed 3x a day, two other groups had almost the same level of glucose) levels in plasma were found. As a group with the best results was determined a group fed 6x a day. This group reached satisfying results in production markers (better than group fed 3x a day but slightly worse than group fed 12x a day). Also, lower growth heterogenity than in group fed 12x a day was observed. Group fed 6x a day also displayed the best working lipid metabolism in contrary to the group fed 12x a day which displayed the disorder of the lipid metabolism. Also, the fin erosion was slightly lower than in a group fed 12x a day.
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The conception of the transcendent in the workings of Shihab al-Din Yahya Suhrawardi
KUČERA, Václav
This work deals with the transcendent in the cosmogonal conception of persian mystic and philosopher Shihab al-Din al-Suhrawardi. In short it discusses his life, works and historicla-cultural context of the arab world in the 12th century. More broadly it deals with the genesis in the philosophy of illumination, the school of ideas of al-Suhrawardi. It analyses the hierarchy of creation from the transcendent creator through the celestial spheres and angelic beings down to the elemental world of matter. It clarifies that the whole process is a continuum and that the Light of lights has even despite his transcendency a direct relationship with everything it creates. Further it contains a few rules given by al-Suhrawardi as a guide to the successful life. At the end of the work is a short treatise about the history of the philosophy of illumination in between the death of al-Suhrawardi and present days.
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Histologické vyšetření raků - zpracování a vyhodnocení vzorků
KUČERA, Václav
The given bachelor thesis focuses on the processing and the examination of the histological samples of crayfish exposed to thiacloprid pesticide. The first part describes methods leading towards processing of the samples. The second part pointed out anatomical, histological and physiological structure of selected tissues - gills and hepatopancreas. The third part classifies histopathological changes induced by selected organic xenobiotics especially hebicides and insecticides. The experimental part discusses histopathological changes of the insecticide thiacloprid.
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Comparison of impact force values amongst improvised and traditional rope fixed instalations
Kučera, Václav ; Michalička, Vladimír (advisor) ; Gajdošík, Jan (referee)
Title: Comparison of impact force values amongst improvised and traditional rope fixed instalations. Objectives: The aim of this work is to measure the resultant impact forces acting on a climber during a fall from an improvised fixed installation, using an improvised ferrata set, by means of an experiment. Furthermore, to compare the measured impact force values with those already measured for traditional fixed installation using ferrata fall arresters. Methods: This paper describes an experiment in which the actual impact force acting on a climber during a fall from an improvised fixed installation using an improvised ferrata set was determined. The aim of the first experiment was to determine the values of the impact forces for a given length of fall. At the same time, to determine the maximum value of the impact force at which the reep cord forming the improvised ferrata set will not break. The second test aimed to determine the resultant values acting on the load when falling into the sag from the dynamic rope, which were then used to compare with the results of the first test. The purpose of the last test was to compare the resultant values of improvised and traditional fixed installations. Each fall length was tested for ten trials whereby after each fall the textile material was replaced...
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Shadowing property of numerical methods for partial differential equations
Brichta, Ondřej ; Kučera, Václav (advisor) ; Knobloch, Petr (referee)
This thesis is focused on the shadowing property of numerical methods for partial differential equations. The goals of this thesis are the application of shadowing theory to the case of linear maps, modification of standard techniques for the purpose of this application and the application of the adapted theory to multistep schemes. In the in- troductory overview, we first focus on a study of the standard shadowing theory, then we formulate basic statements and prove a relationship between a conctractivity and shadowing. Afterwards we find the characterization of the shadowing property for linear maps. In the next sections, we adapt definitions of the shadowing theory to requirements of multistep methods. As an example, we apply the adapted theory to the Dufort-Frankel scheme in the third chapter. At the end of this thesis, remarks on shadowing in general multistep methods and remarks on a relationship between the shadowing property and stability are presented. 1
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