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Structural design of fuselage and tail for racing model
Skála, Adam ; Hájek, Tomáš (referee) ; Pejchar, Jan (advisor)
This bachelor’s thesis surveys fuselage and empennage improvement of an already existing competition aircraft FabricK. Firstly, the introductory part explains the Air Cargo Challenge contest and describes the model. A research then presents possible empennage designs, which is followed by a brief overview of production F3B aircraft. The practical part of thesis introduces construction project of the empennage and the fuselage as well as a weight distribution analysis. Finally, the concluding part will evaluate the imporvement.
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Tilt sensors
Hájek, Tomáš ; Caha, Luděk (referee) ; Beneš, Petr (advisor)
The topic of the Bachelor's thesis are MEMS sensors of inclination, which find their use inside integrated circuits, equipment of aerospace and automobile industry, but also in ordinary electrical appliance. The work serves the reader to build a grasp over production, usage, basic principles. Finally, it offers an overview of sensors to ease the orientation on the market. The design of the physical model, which can be used to prevent the sensor from apperance of mathematical errors, is tested in the practical part.
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Passive Safety Features Implementation into Recovery Systems for General Aviation Airplanes
Hájek, Tomáš ; Slavík,, Svatomír (referee) ; Návrat, Tomáš (referee) ; Jebáček, Ivo (advisor)
The thesis is developed in the context of the continuous improvement of safety in personal aviation. The work focuses mainly on small aircrafts, collectively referred to as General Aviation. This thesis aims to evaluate the feasibility of implementing a passive safety feature in the form of an under-fuselage airbag in the rescue systems of small aircraft. The implementation of such a feature will help to reduce the loads transferred to the crew during a rescue parachute landing and effectively reduce the minimum altitude of the ballistic rescue system. This is a new state-of-the-art solution that is unparalleled in its category. The thesis presents a theoretical framework for solving the problem of shock absorption by airbags in the form of a mathematical model. Subsequently, the thesis presents the validation of the mathematical model based on a set of experimental data obtained for this purpose. The theoretical and practical part of the thesis then deals with the elements that influence the airbag performance, namely actively controlled air vent. The last part of the thesis performs a practical design of the implementation of the under-fuselage airbag in the rescue system of a given aircraft in terms of size, location, activation and filling of the airbag. The proposed system is capable of attenuating the impact of the aircraft from a speed of 15 ms-1, thus reducing the application altitude by 10 %. The weight of the newly designed system is equal to 5 % of the total take-off weight. The contribution of the work lies in the combination of two fields of safety that have not been addressed in this category so far, with the distinct result of improving the safety of small aircraft equipped with a ballistic rescue system.
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The role of phosphoinositides in macropinocytosis
Hájek, Tomáš ; Doubravská, Lenka (advisor) ; Španielová, Hana (referee)
Macropinocytosis is non-selective actin-dependent type of endocytosis. It is important for the normal physiology of some cell types. However, it is used by intracellular parasites which internalise themselves into host cells in this way and also play a role in the nutritional supply in some type of cancer cells. During macropinocytosis a self-organized subdomain of plasma membrane is separated by a diffusion barrier named macropinocytic cup. RAC1-driven actin polymerization is required for membrane protrusion at the cup periphery, where a narrow ring of the actin nucleating factors is present. In contrast, actin dissociation occurs at the base of the cup due to RAS-controlled formation of phosphatidylinositol trisphosphates (PIP3). During cup closure sequential breakdown of PIP3 to phosphatidylinositol and acquisition of the endosomal identity of the newly formed vesicle is necessary. As a result of tubulation in the early stages of macropinocytosome maturation the vesicle decreases in diameter and stabilizes. At late stages the macropinocytic vesicle may fuse with the lysosome, allowing internalized material to enter this degradative organelle. Throughout the process specific types of phosphatidylinositols are part of the membrane providing signal transduction and membrane identity. These phospholipids...
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By-Laws of a Joint-Stock Company
Hájek, Tomáš ; Liška, Petr (advisor) ; Hurychová, Klára (referee)
By-Laws of a Joint-Stock Company Abstract The diploma thesis on the topic of By-Laws of a Joint-Stock Company aims to summarize and analyze in detail all the existing theoretical knowledge and legislation relating to the by-laws of the joint stock company and then apply this knowledge in practice in the analysis of specific by-laws. The work is divided into five chapters. The first chapter deals with the legal nature of the by-laws, their interpretation, their form including issues of non-compliance, issues of conflict with the law and its consequences, and obligations regarding the publication of by-laws and obligations arising from special acts. The second chapter deals with issues of amendments to the by-laws. All possibilities of amending the by-laws are discussed, whether they result from the will of the shareholders or are the result of some other legal facts. Attention is also paid to the effectiveness of the amendments to the by-laws and a one-time breakthrough into them. The third chapter discusses the requirements of the company's by-laws. The individual mandatory requirements arising from the Civil Code and the Business Corporations Act are described in separate subsections. There is also a treatise on optional requirements. Some specific optional requirements are discussed in the by-laws of the...
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Design of the propulsion unit of the competition model airplane with vertical take-off and landing
Pilát, Adam ; Navrátil, Jan (referee) ; Hájek, Tomáš (advisor)
This bachelor’s thesis was written in order to design the propulsion system for a vertical takeoff and landing competition model airplane intended to participate in the New Flying Competition 2022. The task of the thesis was to analyze the rules of the competition and design the propulsion system. The research section includes an analysis on the competition’s rules followed by a review of the propulsion system components. In the next section, a basic analysis of the parameters of the airplane is performed for the purpose of the airplane fulfilling the competition requirements. In the last part of the thesis, a propulsion system components selection method is proposed and carried out. The output of the thesis is a propulsion system suitable for use in the designed airplane.
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Conceptual design of competition model with vertical take-off and landing
Monková, Paulína ; Grim, Robert (referee) ; Hájek, Tomáš (advisor)
The bachelor thesis deals with the conceptual design of the competitive model of the aircraft for the international design student competition held in 2022. The introduction of the work focuses on the analysis of the rules of competition. The research section focuses on possible aircraft configurations and existing commercially available models of the same category as the competition rules. The practical part of the work processes the selection and closer characteristics of the individual parts of the aircraft, the mass analysis process and the determination of the aerodynamic centre of the model. The output of the work is a conceptual design and system model.
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Unmanned aerial vehicle for aerological measurement
Knoth, Adam ; Balážová, Renáta (referee) ; Hájek, Tomáš (advisor)
The main output of this bachelor thesis is the design of aerological measurement, which will allow more frequent measurements. The first part of thesis - a search - mentions the types of radio probes and related legislation for their discharge. The second part proposes a method of aerological measurement, which is compared with classical measurement.
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Ecophysiology of peat bog ericoid subshrubs - freezing resistance and water relations
Daněk, Michal ; Sklenář, Petr (advisor) ; Hájek, Tomáš (referee)
The seasonal changes in freezing resistance and water relations in four dwarf shrub species of Ericaceae family: Vaccinium vitis-idaea, V. myrtillus, V. uliginosum and Oxycoccus palustris in two study areas differing in altitude were studied in this work. To establish the freezing resistance, the plants were sampled eight times, to determine parameters of the water relations, the plants were sampled six times during the growing season of 2009. For the freezing resistance examination, ice nucleation temperature (exotherm) and 50 per cent lethal temperature (LT50) were found. The water relations were described using the parameters derived from the pressure-volume curves: osmotic potential at full turgor, osmotic potential at zero turgor, cytoplasmic water fraction, relative water content at turgor loss and bulk modulus of elasticity. An important seasonal variability in the freezing resistance was found. The highest levels of the freezing resistance were reached in the spring and in the autumn, the lowest levels were found in the summer. There were also changes in the used mechanisms of the freezing resistance - for most of the year, the plants were tolerant, they showed the avoidance mechanism only in the summer. The seasonal changes in the water relation parameter were less unambiguous. The most of...
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Improving the diagnosis of first-episode schizophrenia from magnetic resonance imaging using machine learning
Mikoláš, Pavol ; Hájek, Tomáš (advisor) ; Syka, Josef (referee) ; Hájek, Milan (referee)
Background: Early diagnosis of schizophrenia could improve the outcomes and limit the negative effects of untreated illness. Although participants with schizophrenia show structural/functional alterations on the group level, these findings have a limited diagnostic utility. Novel methods of MRI analyses, such as machine learning (ML), may help bring neuroimaging from bench to the bedside. Here, we used ML to differentiate participants with a first episode of schizophrenia-spectrum disorder (FES) from healthy controls (HC) based on neuroimaging data and compared the diagnostic utility of such approach with the utility of between group comparisons using classical statistical methods. Method: Firstly, we performed a classical fMRI experiment in FES using a self/other- agency task (SA/OA) and compared FES (N=35) versus controls (N=35) using conventional statistics. We than classified FES and healthy controls (HC) using linear kernel support vector machine (SVM) from the resting-state functional connectivity (rsFC) and fractional anisotropy (FA) in 63/63 and 77/77 age- and sex-matched FES and HC participants. We also investigated the between-group differences in rsFC and FA using classical between-group comparisons. Results: FES group exhibited a decreased activation during the emergent SA experience...
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