National Repository of Grey Literature 157 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Zootechnické aspekty inseminace prasnic
Hájek, Petr
The aim of the bachelor thesis is to provide a comprehensive view on the issue of sow insemination and to summarize the current state of knowledge in this area of agricultural production. The bachelor thesis focuses on the description of insemination and on the zootechnical aspects that influence the insemination of sows. As insemination is the most used method of reproduction nowadays, emphasis is placed on the anatomy and physiology of the reproductive apparatus of the sow. Also described are the zootechnical aspects that affect insemination and how these factors influence it. In the last part of the thesis, the insemination itself and its methods of performance are described, discussing the advantages and disadvantages of insemination, including new options such as the semen capsule and its gradual release or a product to influence ovulation.
Finite element modal analysis of a silicone vocal fold filled with fluid
Hájek, P. ; Radolf, Vojtěch ; Horáček, Jaromír ; Švec, J. G.
A three dimensional (3D) finite element (FE) model of a silicone vocal fold (VF) filled with fluid is presented here. The silicone part of the model is based on partial differential equations of the continuum mechanics and consider large deformations. The fluid domain encapsulated in the silicone VF is defined semianalytically as a lumped-element model describing the fluid in hydrostatic conditions. The elongated and pressurized silicone VF was subjected to perturbed modal analysis. Results showed that the choice of the fluid inside the VF substantially influences the natural frequencies. Namely, the water-filling lowers the natural frequencies approximately by half over the air-filling. Besides, the procedure of reverse engineering for obtaining the geometry of the VF from already 3D-printed mold is introduced.
Modelling of blood flow in a carotid artery with stenoses
Štefek, Martin ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This bachelor's thesis deals with the analysis of blood flow in a carotid artery with stenoses in the area of the bifurcation. The current state of knowledge is presented in the theoretical part. As part of the practical part of the work, several 2D models of the artery with stenoses of dif-ferent sizes and distances were created. An ideal mesh of finite volumes was created and select-ed. Using the ANSYS Fluent program, basic hemodynamic parameters such as flow velocity, wall shear stress, pressure and fractional flow reserve (FFR) were evaluated for stationary flow. A time step was determined for the transient flow, and then the flow speed and shear stress on the walls at points were evaluated as a function of time.
Design of the heating system for an office building
Hájek, Pavel ; Horká, Lucie (referee) ; Vyhlídalová, Karolína (advisor)
The aim of the bachelor thesis is to design the heating and hot water supply system for an administrative building in the town Pelhřimov. The building consists of four above-ground floors and one underground floor, which is not heated. The heating is provided by panel radiators, pipe radiators, and underfloor convectors. The heat source consists of a cascade of two gas boilers. The hot water preparation is ensured by an indirect storage water heater. The system operates as a two-pipe system with forced water circulation. The pipes are made of insulated copper.
Computational modelling of the influence of stenoses on blood flow in the carotid artery
Lukáš, Petr ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This diploma thesis deals with blood flow in carotid artery with tandem double stenosis. In the first part there is described cardiovascular system with emphasis on blood and arteries. In the practical part, geometric models of the carotid artery with 30% and 70% stenosis, as well as a model without stenosis, are created. The second stenosis is not included in the model of geometry but modeled using Windkessel effect. Blood is modeled as a non-Newtonian fluid using the Carreau model. After the calculations, the blood flow and arterial wall stress are evaluated, and the results are compared among the different geometry models. Critical values of shear stress, TAWSS, OSI, and FFR, as well as the mass flow rate in the internal carotid artery, are assessed.
Analysis of a Voice Propagation around the Human Body
Zelinka, Martin ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
The main objective of this thesis is to create a suitable realistic 3D model of the human body using photogrammetry and then to perform harmonic acoustic analysis in order to determine the reflection surfaces on the human body and the values of acoustic pressure with its level in the production of the human voice. The result of this work is supported by a search of anatomy and physiology of the vocal tract including models describing the propagation of the human voice in the vocal tract and, last but not least, by comparing the obtained results with previous works.
The impact of freezing of arterial tissue on its stress-strain response
Horák, František ; Hájek, Petr (referee) ; Hrubanová, Anna (advisor)
This bachelor thesis deals with freezing of the arterial tissue at -20 °C and its impact on mechanical properties of artery. The introductory part focuses on basic medical terms related to the issue followed by presentation of scientific publications dealing with artery tissue freezing. The attention is mainly paid to measurements and evaluation of results. The main part of the thesis contains description of the methodology of biaxial tensile test of porcine artery tissue with process of measuring the artery’s Young's modulus. Statistical analysis is used to determine the impact of freezing on mechanical properties of the artery. Description of limitations of this experiment is also included.
Inverse modelling of stresses in deformed configuration of left ventricle
Zajac, Radim ; Hájek, Petr (referee) ; Vaverka, Jiří (advisor)
The bachelor thesis deals with the development of a FEM model of the left ventricle from a freely available stl model obtained from magnetic resonance images and the modification of this model to make it usable for calculation in Ansys MAPDL. The model was defined with isotropic hyperelastic mechanical properties obtained from the actual myocardial properties obtained from tensile tests described in the accompanying literature. A FEM model corresponding to the stress-free state of the left ventricle was obtained and the stress field of the loaded geometry was reconstructed after loading this null geometry. The reconstructed stress field cannot be considered as real due to the idealization of the material and the neglect of the application of pressures on the epicardium of the left ventricle.
Modal Analysis of the Flute
Vojtovič, Adam ; Votava, Tomáš (referee) ; Hájek, Petr (advisor)
The presented bachelor thesis deals with an influence of a fundamental shape and partial sections of flute on frequency of tones. A simple flute is designed and made according to the given formulas. The functionality of the flute is verified by measuring frequencies of each tone. These frequencies are compared with values given analytically and also with values of natural frequencies calculated by finite element method. General information about wind instruments is included in the thesis, too. Besides the clarification of fundamental principles of function of wind instruments, there are also derived fundamental formulas for calculation of natural frequencies of tubes.

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