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On the Effective Machining of New Ceramic Materials
Sámelová, Vendula ; Sedlák, Josef (referee) ; Vrba, Vladimír (referee) ; Humár, Anton (advisor)
Advanced ceramics have long held the front of the list of promising materials for high-tech applications. The most common problem is the high cost of design, production and machining of advanced ceramics parts. The main sense of advanced ceramics processing techniques development is affordable, high-volume production. The dissertation is focused on SiC silicon carbide grinding. SiC is used in the design of machine parts due to its excellent properties The deep knowledge of the diamond wheel grinding process is important because it is one of the finishing methods and therefore has a direct impact on the quality and strength of the SiC parts. The key issue here is the overall surface quality of the parts after diamond wheel grinding and the knowledge of the factors that influence the surface quality. These include, in particular, grinding vibrations. The main purpose of the thesis is to create a system of specific scientific and technical information, which will allow applying optimal technological procedures in the processing of ceramic components. The theoretical part of the thesis contains an analysis of the current state of the art in the advanced ceramics machining area, detailed analysis of the ceramics grinding with diamond grinding wheels, signal analysis theory and analysis of surface quality assessment methods. The experimental part contains analysis and discussion of the results obtained during the monitoring of the silicon carbide grinding process with a diamond grinding wheel. Various diagnostic methods have confirmed the presence of vibrations at a frequency close to the speed frequency of the grinding wheel, which had a significant, negative effect on the samples surface quality. Vibration diagnostics has identified a specific source of vibration (clamping of the workpiece) and it has been removed subsequently.
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Effective Machining Of Fiber Reinforced Composite Materials
Sedláček, Jan ; Janáč, Alexander (referee) ; Vrba, Vladimír (referee) ; Klement, Josef (referee) ; Humár, Anton (advisor)
The objectives for this dissertation are to push forward the current state of knowledge in the area of machining fiber-reinforced plastic (FRP). The most common machining operation performed on these materials is drilling owing to the need for component assembly in mechanical pieces and structures. Among the defects caused by drilling, delamination appears as to be of the most critical and may occur at both the entrance and exit plane. A number of theoretical and experimental studies have been made to create an analytical model of delamination in composite laminates. In this dissertation, the critical thrust force (force which initiates the delamination) is predicted using linear elastic fracture mechanics - assuming Mode I. Delamination is investigated by studying the evolution of feed force and torque applied by the tool on the workpiece. A four components piezoelectric dynamometer KISTLER 9272 with special PC-software is used for measuring and evaluating of torque and cutting forces, when drilling two different composite materials: carbon/epoxy laminate fabricated by hand lay-up technique and glass/polyester composite made by pultrusion. Wear mechanisms and location of the wear on the tool are also investigated (with respect to cutting material). The tool wear is measured with help of a common workshop microscope and recorded with scanning electron microscope PHILIPS XL30. Drilling experiments are performed to give complex technical information (i.e. cutting conditions, tool geometry, tool wear and so on) which enables efficient machining of composite materials. Delamination-free drilling is given special emphasis in the experiments. Methods of statistical analysis (DOE) are used to determine which factors have the most influence on delamination.
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Influence of Grinding Tool Vibration on the Ground Surface Texture
Lukovics, Petr ; Vrba, Vladimír (referee) ; Tykal, Miroslav (referee) ; Pernikář, Jiří (advisor)
Thesis solves the problem of influence of variable process conditions during grinding on surface texture parameters, provides precision of measurement methods, assessed by laser interferometry measurement methods and piezoelectric measurement of vibration of technological equipment and processes using statistical methods the correlation between the amplitude of oscillation and on surface texture parameters. Further it provides the prediction of the impact of input parameters to the output parameters of the technological process for a long-term perspective.
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Application of molecular and cellular biology methods in research of protozoa Eimeria
Vrba, Vladimír
Eimerie jsou jednobuněční prvoci z kmene Apicomplexa způsobující nemoc kokcidiózu, která je příčinou velkých ekonomických ztrát především v drůbežářském průmyslu. Cílem této práce bylo vyvinout nové molekulární metody a vyřešit některé problémy, což by bylo cenným příspěvkem v oboru, využitelným jak ve výzkumu tak i v praxi. Protože imunita proti eimeriím je druhově přísně specifická, je důležité znát jednotlivé druhy a dokázat je rozpoznávat. Tradiční diagnostické postupy spoléhají na klasické metody jako je určování morfologie oocyst pod mikroskopem, stanovování prepatentní periody nebo hodnocení lézí způsobených parazitem. Určování druhů těmito způsoby je však časově velice náročné a často nespolehlivé, hlavně v případech, kdy analyzujeme směs více druhů, jejichž parametry se překrývají. I když metody určování druhů využívající klasickou PCR již existují, tyto metody postrádají výhody nabízené real-time kvantitativní PCR (qPCR). Prvním cílem této práce bylo vyvinout qPCR metody pro detekci a kvantifikaci sedmi druhů kuřecích eimerií. Cílem byla vysoká specifita a maximální pokrytí všech různých kmenů každého druhu, proto byly jako cílové sekvence hledány jednokopiové nepolymorfní oblasti. Užitečnost metody byla demonstrována analýzou vzorků z terénu. Dalším cílem práce bylo vyřešení postavení...
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On the Effective Machining of New Ceramic Materials
Sámelová, Vendula ; Sedlák, Josef (referee) ; Vrba, Vladimír (referee) ; Humár, Anton (advisor)
Advanced ceramics have long held the front of the list of promising materials for high-tech applications. The most common problem is the high cost of design, production and machining of advanced ceramics parts. The main sense of advanced ceramics processing techniques development is affordable, high-volume production. The dissertation is focused on SiC silicon carbide grinding. SiC is used in the design of machine parts due to its excellent properties The deep knowledge of the diamond wheel grinding process is important because it is one of the finishing methods and therefore has a direct impact on the quality and strength of the SiC parts. The key issue here is the overall surface quality of the parts after diamond wheel grinding and the knowledge of the factors that influence the surface quality. These include, in particular, grinding vibrations. The main purpose of the thesis is to create a system of specific scientific and technical information, which will allow applying optimal technological procedures in the processing of ceramic components. The theoretical part of the thesis contains an analysis of the current state of the art in the advanced ceramics machining area, detailed analysis of the ceramics grinding with diamond grinding wheels, signal analysis theory and analysis of surface quality assessment methods. The experimental part contains analysis and discussion of the results obtained during the monitoring of the silicon carbide grinding process with a diamond grinding wheel. Various diagnostic methods have confirmed the presence of vibrations at a frequency close to the speed frequency of the grinding wheel, which had a significant, negative effect on the samples surface quality. Vibration diagnostics has identified a specific source of vibration (clamping of the workpiece) and it has been removed subsequently.
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Application of molecular and cellular biology methods in research of protozoa Eimeria
Vrba, Vladimír ; Škvor, Jiří (advisor) ; Čepička, Ivan (referee) ; Hampl, Vladimír (referee)
Eimeria is an apicomplexan parasite causing disease coccidiosis that is most prominent in poultry farming industry. This thesis is aimed to develop new molecular tools and resolve issues that would be a valuable contribution in the field from both research and industry perspective. Because immunity to Eimeria is strictly species- specific, it is important to know and recognize correctly all species that parasitize the host. Traditional diagnostic approaches rely on classical methods such as oocyst morphology determination under the microscope, measurement of prepatent period or in-vivo assessment of lesions caused by this parasite. However, diagnostics of individual species using these methods is very time-consuming and it is often unreliable, especially when mixture of multiple species whose parameters overlap is analyzed. Methods utilizing conventional PCR to distinguish species already exist, however, they lack advantages offered by quantitative real-time PCR (qPCR). The first aim of this thesis was to develop qPCR assays for detection and quantification of seven Eimeria species which infect chicken utilizing single-copy non-polymorphic targets in order to ensure maximal specifity and coverage of all strains of each species. Usefulness of this method was demonstrated by analysis of field...
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Application of molecular and cellular biology methods in research of protozoa Eimeria
Vrba, Vladimír
Eimerie jsou jednobuněční prvoci z kmene Apicomplexa způsobující nemoc kokcidiózu, která je příčinou velkých ekonomických ztrát především v drůbežářském průmyslu. Cílem této práce bylo vyvinout nové molekulární metody a vyřešit některé problémy, což by bylo cenným příspěvkem v oboru, využitelným jak ve výzkumu tak i v praxi. Protože imunita proti eimeriím je druhově přísně specifická, je důležité znát jednotlivé druhy a dokázat je rozpoznávat. Tradiční diagnostické postupy spoléhají na klasické metody jako je určování morfologie oocyst pod mikroskopem, stanovování prepatentní periody nebo hodnocení lézí způsobených parazitem. Určování druhů těmito způsoby je však časově velice náročné a často nespolehlivé, hlavně v případech, kdy analyzujeme směs více druhů, jejichž parametry se překrývají. I když metody určování druhů využívající klasickou PCR již existují, tyto metody postrádají výhody nabízené real-time kvantitativní PCR (qPCR). Prvním cílem této práce bylo vyvinout qPCR metody pro detekci a kvantifikaci sedmi druhů kuřecích eimerií. Cílem byla vysoká specifita a maximální pokrytí všech různých kmenů každého druhu, proto byly jako cílové sekvence hledány jednokopiové nepolymorfní oblasti. Užitečnost metody byla demonstrována analýzou vzorků z terénu. Dalším cílem práce bylo vyřešení postavení...
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Influence of Grinding Tool Vibration on the Ground Surface Texture
Lukovics, Petr ; Vrba, Vladimír (referee) ; Tykal, Miroslav (referee) ; Pernikář, Jiří (advisor)
Thesis solves the problem of influence of variable process conditions during grinding on surface texture parameters, provides precision of measurement methods, assessed by laser interferometry measurement methods and piezoelectric measurement of vibration of technological equipment and processes using statistical methods the correlation between the amplitude of oscillation and on surface texture parameters. Further it provides the prediction of the impact of input parameters to the output parameters of the technological process for a long-term perspective.
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Effective Machining Of Fiber Reinforced Composite Materials
Sedláček, Jan ; Janáč, Alexander (referee) ; Vrba, Vladimír (referee) ; Klement, Josef (referee) ; Humár, Anton (advisor)
The objectives for this dissertation are to push forward the current state of knowledge in the area of machining fiber-reinforced plastic (FRP). The most common machining operation performed on these materials is drilling owing to the need for component assembly in mechanical pieces and structures. Among the defects caused by drilling, delamination appears as to be of the most critical and may occur at both the entrance and exit plane. A number of theoretical and experimental studies have been made to create an analytical model of delamination in composite laminates. In this dissertation, the critical thrust force (force which initiates the delamination) is predicted using linear elastic fracture mechanics - assuming Mode I. Delamination is investigated by studying the evolution of feed force and torque applied by the tool on the workpiece. A four components piezoelectric dynamometer KISTLER 9272 with special PC-software is used for measuring and evaluating of torque and cutting forces, when drilling two different composite materials: carbon/epoxy laminate fabricated by hand lay-up technique and glass/polyester composite made by pultrusion. Wear mechanisms and location of the wear on the tool are also investigated (with respect to cutting material). The tool wear is measured with help of a common workshop microscope and recorded with scanning electron microscope PHILIPS XL30. Drilling experiments are performed to give complex technical information (i.e. cutting conditions, tool geometry, tool wear and so on) which enables efficient machining of composite materials. Delamination-free drilling is given special emphasis in the experiments. Methods of statistical analysis (DOE) are used to determine which factors have the most influence on delamination.
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Rozšíření stávající ornitologické bibliotéky a vytvoření bibliotéky savců
TKV, Praha ; Vrba, Vladimír
Cílem projektu je vypracovat a zavést do užívání vzdělávací programové vybavení zajišťující postupné vedení bibliotéky ptáků, savců, plazů, obojživelníků, ryb a hmyzu obsahující seznam prací souvisejících s uzemím ČR a nebo vydané českými občany.Byla rozšířena stávající ornitologická bibliotéka a vytvořena bibliotéka savců, doplněny citace z odborných časopisů o ptácích a savcích. CD-ROM obsahuje instalační program umožňující práci s bibliotékou.
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