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Design of mobile stand for suspending of electrodynamic exciter for aeroelastic phenomena testing in aviation
Vojáček, Jan ; Löffelmann, František (referee) ; Navrátil, Jan (advisor)
This Bachelor thesis deals with the design of mobile stand for carrying out ground vibration tests in aviation applications. These tests mainly judge the tolerance of aircraft against flutter. The start of the thesis deals with the teoretical background of aeroelasticity together with the historical events that led to the origins of research of such phenomenons. The second part of the tesis clarifies the motivation for designing the stand through overview of simmilar equipment avaiable on the market and through introducing the equipment used at the aircraft testing laboratory at the Institute of Aerospace Engineering. Third part of the thesis states possible approaches to the overal design of the stand and then crosses over to the chapter that discusses the chosen solution of the design. At the end there are introduced the results of modal analysis. These results state the natural frequencies occuring in the range of frequencies that normally occur while testing.
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Effect of initiation on bulk polymerization of styrene
Vojáček, Jakub ; Běťák, Lukáš (referee) ; Kučera, František (advisor)
Bachelor thesis summarizes in the literature part findings on field of the radical initiation of styrene bulk polymerization. Especially polymerization using mono- and bifunctional initiators, further fotoinitiation and thermal initiation of styrene polymerization. The practical part is focused on monitoring the effects of polymerization conditions on monomer conversion, molecular weight, density and viscosity of the prepolymers. Experiments were performed with monofunctional initiator (dibenzoylperoxide), at atmospheric pressure, with polymerization temperature 91 °C, and various concentrations of initiator. Determination of monomer conversion was carried out gravimetrically, the density was determined by titration method and viscosity using the Stokes equation. Molecular weights were then calculated using Kuhn-Mark-Houwink-Sakurad equation.
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Influnce of chemical composition on mechanical properties of LLDPE stretch film
Vojáček, Jakub ; Tocháček, Jiří (referee) ; Poláček, Petr (advisor)
Thesis summarizes the problems of production and use of stretch film. The change of strength, ductility and relative relaxation effect in different times of drawing from role in three weeks was observed. Further, change of strength and ductility due to changes in the rate of deformation, exposure to accelerated aging in a UV chamber and changes in the loading direction were observed. Mechanical tests were realized on a tensile tester, relaxation tests on DMA and crystallinity changes were observed on the DSC. Relationship between chemical composition of stretch film and mechanical and thermomechanical properties were studied. It was found that chemical composition essential for stretch film properties. However, due to the impossibility to distinguish effects of chemical composition and process parameters was impossible to find clear relation describing this relationship.
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Mobile Open Source application development for OS Android in Kotlin
VOJÁČEK, Jakub
The aim of my bachelor's thesis will be to analyze the creation of Open Source applications for mobile devices with Android OS in the programming language Kotlin. Kotlin is a statically typed programming language running on top of a Java Virtual Machine, with the option of compiling into JavaScript. It is designed for interoperability with Java libraries, it even depends on some kernel libraries. In 2017 Google designated Kotlin as the official language for Android development instead of the originally used Java language. The bachelor's thesis will elaborate the development of the application in the language of Kotlin, the output of the work will be a set of practical examples, smaller applications, and the main, larger, application Department of Informatics PF JU. The application will be tested on available platforms (phone, tablet) and on several versions of the Android OS, part of the work will be publishing the finished application on Google Play.
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Design of mobile stand for suspending of electrodynamic exciter for aeroelastic phenomena testing in aviation
Vojáček, Jan ; Löffelmann, František (referee) ; Navrátil, Jan (advisor)
This Bachelor thesis deals with the design of mobile stand for carrying out ground vibration tests in aviation applications. These tests mainly judge the tolerance of aircraft against flutter. The start of the thesis deals with the teoretical background of aeroelasticity together with the historical events that led to the origins of research of such phenomenons. The second part of the tesis clarifies the motivation for designing the stand through overview of simmilar equipment avaiable on the market and through introducing the equipment used at the aircraft testing laboratory at the Institute of Aerospace Engineering. Third part of the thesis states possible approaches to the overal design of the stand and then crosses over to the chapter that discusses the chosen solution of the design. At the end there are introduced the results of modal analysis. These results state the natural frequencies occuring in the range of frequencies that normally occur while testing.
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The metabolic response to acute coronary syndrome focusing on tissue factor, metalloproteinases and soluble CD40 ligand
Bis, Josef ; Vojáček, Jan (advisor) ; Mates, Martin (referee) ; Vítovec, Jiří (referee)
The metabolic response to acute coronary syndrome focusing on tissue factor,, metalloproteinases and soluble CD40 ligand Introduction: The cause of acute coronary syndrome is unstable plaque and its rupture. Pathogenesis is complex and requires various mechanisms and depends both on the composition of plaque and thrombotic activity of blood. Objectives: The main goal of this work was to assess local levels of plasma tissue factor (TF), tissue factor inhibitor (TFPI), tissue metalloproteinases (MMP-2, 3 and 9) and inhibitor of metalloproteinases-2 (TIMP-2), a highly selective C-reactive protein (CRP) and soluble CD40 ligand (sCD40L) in patients with acute coronary syndrome and with stable angina pectoris in the systemic circulation, the coronary sinus and to determine the time course of blood levels in patients with acute coronary syndrome. Methods and results: Study population include patients with coronary artery disease (CAD). In 24 patients with stable CAD (SCAD) at time of diagnostic coronary angiography, we withdrew samples from the coronary sinus (CS), femoral vein (VF) and left coronary artery (LMCA). In 29 patients with acute coronary syndrome (ACS) we took samples of venous blood also 24 hours and 7 days from the start. The samples were fixed levels of TF, TFPI, MMP-2, 3 and 9, TIMP-2, CRP, and...
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Radial approach to coronary catheterizations and interventions
Bernat, Ivo ; Rokyta, Richard (advisor) ; Vojáček, Jan (referee) ; Ošťádal, Petr (referee)
Radial approach in coronary catheterizations and interventions has been only an alternative of the femoral approach. But due to some important advantages radial approach has a chance to become the first choice in majority of catheterized patients. The most important advantage is the reduction of vascular access site bleeding complications. Additonal benefits are patient satisfaction, cost reduction, shorter hospital stay and possibility of the same-day discharge catheterizations and interventions. The aim of our work was to try to answer three open questions: 1. is it possible to catheterize majority of our patients from the left radial artery when 90% of them are right-handed ? 2. what is the optimal care for the radial artery after the procedure in prevention and treatment of radial artery occlusion? 3. is it effective to implement radial approach in primary PCI as a first approach for STEMI patients? The first part relates the left radial approach. After construction of our special variable support for the left arm and forearm we succesfully used this approach in our studies in almost 90% of patients. The second part of this work contains our randomized trial comparing two different doses of unfractionated heparin in prevention of radial artery occlusion after diagnostic cardiac catheterizations....
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Diagnosing vascular prosthesis infection by means of the FDG-PET/CT
Špaček, Miroslav ; Bělohlávek, Otakar (advisor) ; Vojáček, Jan (referee) ; Gregor, Zdeněk (referee)
Introduction: Vascular prosthesis infection (VPI) is a life-threatening complication in 0.5- 5% of cases. Early and reliable diagnosis is a necessity for adequate treatment. Computed tomography (CT) is the gold standard diagnostic method used world-wide with excellent results, but in cases of advanced graft infection. Low grade infections in non-acute patients are a diagnostic challenge requiring a new method with good diagnostic accuracy. The aim of this work is to define the accuracy of 18 F-FDG PET/CT in these settings and to identify essential parameters of its evaluation. Material and Methods: Seventy-six consecutive patients with total of 96 vascular prosthetic grafts in which infection was suspected underwent PET/CT examination prospectively. PET/CT scans were analysed in terms of presence and intensity of focal and diffuse FDG uptake, presence of anastomotic pseudoaneurysm, irregular boundary of infiltration, combination of these, and uptake ratio between graft and blood background. Also, other parameters like white blood cell count, C-reactive protein, and microbiological cultures were tested. The final diagnosis (gold standard) was based on operative/histopathological finding or >6 months clinical follow up. Results: In our series the prevalence of VPI was 57.3 % (55/96 prostheses). Among various...
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Implantation of cryopreserved mitral allograft into tricuspidal position in an experiment with sheep: Technical aspects of implantation and immediate results evaluated with the aid of epicardial echocardiography
Vojáček, Jan ; Špatenka, Jaroslav (advisor) ; Dominik, Jan (referee) ; Třeška, Vladislav (referee) ; Černý, Štěpán (referee)
Aortic, mitral and pulmonary valve replacement is routinely performed with reasonable clinical results. But the optimal substitute for the tricuspid valve remains controversial. Contemporary prostheses either mechanical or bioprosthetic are associated with a high risk of thrombosis and/or structural failure. Mitral allografts could have advantages over existing prostheses, especially in patients with infectious endocarditis. We describe our first experience with cryopreserved mitral allograft processing and implantation into the tricuspid position in a sheep experimental model. Material and Methods: We subjected 20 sheep (age 1 year, weight 23 - 36 kilograms) to general anesthesia and a left thoracotomy. An epicardial echocardiographic study was performed and the mitral valve was harvested. Donor animals were put to death by intravenous anesthetics injection. Allografts were immersed into cultivation medium E 199 with an antibiotic cocktail. After 24 hours storage at the temperature of 37.0oC the valves were kept at + 5 to + 7 oC over a period of 3-5 days. Then they were transferred into the cryoprotective solution (E 199 with 10% dimethylsulfoxide) and sealed into plastic bags using a double-layer technique. Finally, they were programmed cooled and stored in the liquid stage of liquid nitrogen (- 196 oC)...
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The Prevention of the organ damage after out of hospital cardiac arrest
Karásek, Jiří ; Widimský, Petr (advisor) ; Vojáček, Jan (referee) ; Moťovská, Zuzana (referee) ; Bonaventura, Jiří (referee)
The publication summarises in four original papers the authors' results in out-of-hospital cardiac arrest (OHCA). The first paper presents a prospective observational study comparing the effect of mechanical chest compression (LUCAS) and manual chest compression (non-LUCAS) on the 30-day and 180-day survival rate of the patients affected by OHCA. The study included 278 patients (144 underwent mechanical chest compression - LUCAS, and 134 manual chest compression - non-LUCAS). There were no significant differences in restoration of spontaneous circulation (ROSC): (25% in LUCAS vs 30.6% in non-LUCAS, p = 0,35). However, we observed significantly more conversions to shock rhythm in the LUCAS group (20.7% vs 10.10%, p = 0,04). The 30-day survival rate was significantly worse in the LUCAS group (5.07% vs 16.31% in non-LUCAS, p = 0,044). In the case of 180-day survival, no significant differences were detected (9.42% in LUCAS vs 5.45% in non-LUCAS, p = 0,25). The second study examined mechanical chest compression-related injuries as a possible explanation for the mechanical compression failure in survival rates. This retrospective observational study relied on 630 patients who died during CPR that involved mechanical or manual chest compressions. The data were drawn from autopsy reports of all patients....
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