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Concentration of grease constituents in the EHD contact and its surroundings
Palán, Miroslav ; Čermák, Jan (referee) ; Košťál, David (advisor)
The thesis focused on the study of the effect of thickener particle size and speed on the concentration of grease particles (thickener and base oil) in the contact and its close surroundings. The calibration images were taken on a sandwich module and the experiments were carried out in a ball-on-disk configuration. The distribution of particles in the grease was investigated by fluorescence microscopy, which allows separate observation of the individual particles. The results showed that the particle size of the thickener fundamentally affects its concentration in and around the contact. The larger particle size is found in the lubricant, the higher is it concentration in the contact. The work also shows the effect of changing the velocity on the change in concentration of the individual components and the connection of the transition velocity with the distribution of the components. The work gives a new perspective on the behavior of greases and provide useful knowledge for the development and optimization of greases for different applications.
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Dispersion of particulate matter pollution from electric vehicles in urban areas using CFD
Lipka, Jakub ; Pospíšil, Jiří (referee) ; Linda, Jakub (advisor)
There is an opinion across the society, that electric vehicles (EV) are emission-free alternative to vehicles using internal combustion engines (ICEV). This is not true. Although electric vehicles do not produce emissions connected to internal combustion, they still produce non-combustion emissions that are emitted into surrounding air. Non-combustion emissions in question are brake wear particles (BWP), tire wear particles (TWP) and road wear particles (RWP). These emissions, due to EV’s greater mass, tend to be higher compared to ICEVs. Therefore, in this thesis, model of dispersion of non-combustion emissions generated by EVs was created using CFD consisting of two models – airflow model around EV and particle dispersion model. It was found that those emissions are captured and distributed by airflow, mainly thanks to vortices generated in the wake zone behind the vehicle. Those particles can be suspended up to 1,9 m into the air and up to 2,5 m laterally away from the vehicle. Thanks to that there is a risk of pedestrian inhaling air with high concentration of those particles in places near roads like pavements.
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Analysis of mechanical loads of selected structural parts of the excavator during operation
Busta, Michal ; Maňas, Pavel (referee) ; Vosynek, Petr (advisor)
This thesis is focused on the issue of computational modeling of soil harvesting while using the compact excavator from the company DOOSAN BOBCAT EMEA s.r.o.. The solution consists in creating two computational models in Rocky DEM and Ansys Mechanical. Rocky DEM software is used to solve the disconnection of soil by excavator components using the discrete element method. The outcome includes courses of forces and moments during the particular time of the individual joints of the model that was used. The obtained courses are then applied as an external load to the joint of a selected structural part of the analyzed model using a kinematic model in ANSYS Mechanical. The kinematic model consists of simplified geometry models of individual parts of the excavator arm, and a more detailed geometry model of the analyzed part of the arm. All the parts are connected to each other by rotational bonds representing joints. A static structural analysis of the mechanical stress is performed in ANSYS Mechanical for the prepared model during the simulated process. Finally, the selected structural part is assessed with respect to the elastic limit and fatigue strength.
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Atmospheric particles and their measurement
Kantor, Radek ; Elcner, Jakub (referee) ; Bělka, Miloslav (advisor)
The aim of this work is to find out what aerosols are, what properties they possess and how they can be measured. In today’s age, the term particles in the atmosphere, is highly talked about because it is known, that particles in the air can be inhaled and cause health problems. By measuring properties of particles from different sources, we can find out the danger level of such particles. One sample was measured by several different techniques and analyzed. Thanks to this analysis we can determine size distribution of particles and then their possible danger.
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Acceleration of Particle Swarm Optimization Using GPUs
Krézek, Vladimír ; Schwarz, Josef (referee) ; Jaroš, Jiří (advisor)
This work deals with the PSO technique (Particle Swarm Optimization), which is capable to solve complex problems. This technique can be used for solving complex combinatorial problems (the traveling salesman problem, the tasks of knapsack), design of integrated circuits and antennas, in fields such as biomedicine, robotics, artificial intelligence or finance. Although the PSO algorithm is very efficient, the time required to seek out appropriate solutions for real problems often makes the task intractable. The goal of this work is to accelerate the execution time of this algorithm by the usage of Graphics processors (GPU), which offers higher computing potential while preserving the favorable price and size. The boolean satisfiability problem (SAT) was chosen to verify and benchmark the implementation. As the SAT problem belongs to the class of the NP-complete problems, any reduction of the solution time may broaden the class of tractable problems and bring us new interesting knowledge.
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Particle Systems
Bedecs, Jakub ; Maršík, Lukáš (referee) ; Kajan, Rudolf (advisor)
This bachelor's thesis deals with the implementation of particle systems with the usage of calculation power of GPU. The purpose of this work is to describe all important facts about the particle systems construction and to show up various possibilities of its usage. It analysis the abilities of modern shaders and their usage for calculation of particles movement. The basis of this work is the analysis of the implemented application, which is able to dynamically change all parameters of the system.
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Preparation and application particles from copolymer of P(3HB-co-4HB)
Ostanina, Kseniia ; Sedláček, Petr (referee) ; Obruča, Stanislav (advisor)
This bachelor thesis deals with preparation of particles from poly(3-hydroxybutyráte-co-4-hydroxybutyráte). Copolymer was dissolved in acetone and then the solution had been dosed into the anti-solvents. Acetone and anti-solvent are perfectly miscible. Theoretical part focuses on the properties of the copolymer, its production and potential use in medical applications. In the experimental part the copolymer was dripped into selected anti-solvents by syringe and pipette above and below the surface of anti-solvent. The following anti-solvent were chosen: water, methanol, dimethylsulfoxid (DMSO), 50 % acetone-water, 75% acetone-water, 50 % methanol-water, 75 % methanol-water mixtures. There were three copolymers used with different compositions of 4HB units (63 %, 87 % a 33 %). Copolymer composition was analyzed by gas chromatography. Copolymers were prepared by bacterial strain Aneurinibacillus sp. H1. Due to the results particles of size approximately 100-500 nm can be prepared by methods described in this work. The produced particles can be successfully used in medical applications.
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Advanced laser diagnostic systems to measure flow field
Loutocký, Petr ; Lízal, František (referee) ; Jedelský, Jan (advisor)
The aim of this work is to give readers a comprehensive view of the present laser methods for measuring the velocity of fluid flow. The methods are classified and compared according to various criteria. Individual techniques are briefly outlined their principles of measurement, options and range of applications. Furthermore, this work discusses the advantages and disadvantages, appropriate areas of application and the basic parameters. At the end we can find a sample analysis of data measured by one method.
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Possibilities of encapsulation of particular types of macromolecules and bacteria
Kapar, Jiří ; Obruča, Stanislav (referee) ; Márová, Ivana (advisor)
Presented diploma thesis is focused on testing encapsulation methods of enzymes and probiotic bacteria. In the theoretical part a summary of different encapsulation techniques used in food industry is given. Further, materials for encapsulation, above all polysaccharides are presented. Next, some procedures of encapsulation of biopolymers and microorganisms – mainly enzymes and probiotic cultures are discussed. In the experimental part methods for preparation of several types of particles based on polysaccharides and liposomes are introduced. Particles were used for encapsulation of selected hydrolytic enzymes and probiotic strains Bifidobacterium breve a Lactobacillus acidophilus. The encapsulation effectiveness was evaluated by analysis of total proteins and enzyme activities. Particles sizes and their stability in water, in selected model foods and model body fluids were observed, too. According to results obtained in this work it was found that encapsulation of enzymes into polysaccharide particles were succesfull in all types of particles (encapsulation effectivness was more than 50 %). Polysaccharide particles showed a very good stability in body fluids as well as in model foods. As the most suitable materials for enzymes encapsulation chitosan and liposomes were found. Polysaccharide particles were used also for the encapsulation of microorganisms. The stability of particles with lactic acid bacteria was similar to particles containig enzymes, very good stability was verified aslo in model foods and model body fluids. Encapsulation enables long-term stabilization of biologically active compounds as well as posibility of their transport and controlled releasing in gastrointestinal tract. Encapsulation of probiotic bacteria could preserve their viability and long-term survival until the product expiration date. Thus, encapsulation is one of the most promissing procedures for production of foods and food suplements of great quality and high additional value.
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