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Lifetime measurement of current carriers in silicon solar cells structures
Macháček, Martin ; Hégr, Ondřej (referee) ; Boušek, Jaroslav (advisor)
This thesis deals with a lifetime measurement of current carriers in silicon solar cell structures. In the first chapter there is a description of several recombination models and their participation at a final effective lifetime value. By using these recombination models in a computer simulation it is possible to receive approximate evaluation of some important silicon solar cell structure parameters. The PC1D simulation program was used for this thesis. For the lifetime measurement of real test-wafers two methods were used: QSSPC (quasi-steady-state photoconductance) and MW-PCD (microwave photoconductance decay). There is a detail description of these methods, used measurements machines and differences between both of them in the chapter four. The main objective of the thesis is mentioned in the last chapter, which is mainly focused on a chemical passivation of silicon wafers and deals with a problem of post-passivation wafer cleaning. There are three passivation techniques mentioned: the iodine in ethanol solution, the iodine and polymer in ethanol solution and the quinhydron in methanol solution. In two cases a results, that are adequate to return the tested wafers in the manufacture process, were achieved.
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Implementation of laser technology
Urban, Jan ; Mouralová, Kateřina (referee) ; Osička, Karel (advisor)
The aim of this thesis is to describe the replacement of wire cutting laser cutting for cutting inserts made of hard material. Description of current situation in the company Vydona, tender and choice of laser and the need for post-laser workshop. The next section deals with the cutting of a particular sample. The last part of the technical economic assessment are calculated hourly rates of machines and the time and cost loads of different cutting inserts.
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Creating a knowledge base for the diagnosing of diseases
Macháček, Daniel ; Steinerová, Kateřina (referee) ; Jirsík, Václav (advisor)
This bachelor thesis is focused on problematic of creation knowledge base. It is describing basics of expert systems, their function and possible usage in modern world. In result of this thesis is knowlenge base in web aplication NPS able to diagnose diseases of hematology-oncology and that is proving possibility for use in real life. Knowledge base was created in cooperation with experts in the medical field and contains real data.
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Design of the PKD cutting edge cutter
Křehlík, Luboš ; Trčka, Tomáš (referee) ; Polzer, Aleš (advisor)
The thesis deals with the design, construction, production and testing of cutters with polycrystalline diamond cutting edges. Polycrystalline diamond is a suitable cutting material for machining very abrasive materials such as aluminum alloys or composite materials. The design of the tool is focused on the application of the chip breaker on the front of the tool. The aim of the solution is to reduce the cutting force in the machining of the aluminum alloy used in the aerospace industry. The first part of the thesis deals with problems related to milling technology. The practical part describes the design and construction of prototype cutting tools. Three tools were designed for experimental measurement. The technology of cutting tools made from super hardened cutting materials with laser technology is presented. The experimental part of the thesis is a measurement of the cutting force according to cutting parameters and machined material.
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Analysis of the force loading of the end mills with PCD considering their sharpening
Trčka, Tomáš ; Kalivoda, Milan (referee) ; Polzer, Aleš (advisor)
Measurement of the force loading is a significant type of measurement in mechanical engineering applied to analyse important aspects in the machining process. In addition to the determination of specific material constants, it is possible to analyse, for example, various machining strategies, geometries of tools or the degree of wear of the cutting edges of cutting tools. This master’s thesis deals especially with the last two mentioned aspects which are subjects of an experiment on end mills with PCD inserts sharpened by a different technology. In the introductory part the cutting forces are theoretically analysed along with their measurement possibilities and the technology of the production of the mills including their sharpening – WEDM and EDM-G. One chapter is concerned with the milling of plastic materials, as PVC was the material used for the workpiece during the experiment. The first experimental part is devoted to the analysis of sharpened tools followed by the measurement of forces using the piezoelectric dynamometer and the subsequent analysis of the influence of the different tool geometry. The last conducted experiment monitors how the overall cutting forces of individual end mills sharpened by different technology changed over specific milling time slots.
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Research of a Cutting Tool with a Diamond Active Part
Trčka, Tomáš ; Mrkvica, Ivan (referee) ; Chladil, Josef (referee) ; Polzer, Aleš (advisor)
The submitted dissertation is focused on research in the field of milling tools with a diamond active part when machining one of the difficult-to-machine materials (Ti-6Al-4V). The first chapters are dealing with a theoretical analysis of a given workpiece material and polycrystalline diamond (PCD) as a super-cutting material. One of the theoretical chapters is also focused on tool sharpening technologies, for which the hardness of a diamond is no longer a crucial factor. The main part of the dissertation is the design, construction and production of tools taking into account the technological design, along with the application of modern trends and technologies enabling innovation and progressive design – from the perspective of macro/micro tool geometry and insert sharpening technology. The research was focused on the application of own inserts on the insert rake face and specific sharpening technologies EDMG, WEDM and LASER. One modification of the face of the PCD insert with a laser was subsequently applied to prototype circle segment end mill. Detailed analysis of manufactured tools and workpiece material was performed by electron, optical and digital microscopy. The measured parameters in the subsequent analysis of the machining process were force loading, tool wear, temperature measurement using a thermal imaging camera and analysis of the machined surface in the form of microhardness and roughness measurements.
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Creating a knowledge base for the diagnosing of diseases
Macháček, Daniel ; Steinerová, Kateřina (referee) ; Jirsík, Václav (advisor)
This bachelor thesis is focused on problematic of creation knowledge base. It is describing basics of expert systems, their function and possible usage in modern world. In result of this thesis is knowlenge base in web aplication NPS able to diagnose diseases of hematology-oncology and that is proving possibility for use in real life. Knowledge base was created in cooperation with experts in the medical field and contains real data.
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Design of the PKD cutting edge cutter
Křehlík, Luboš ; Trčka, Tomáš (referee) ; Polzer, Aleš (advisor)
The thesis deals with the design, construction, production and testing of cutters with polycrystalline diamond cutting edges. Polycrystalline diamond is a suitable cutting material for machining very abrasive materials such as aluminum alloys or composite materials. The design of the tool is focused on the application of the chip breaker on the front of the tool. The aim of the solution is to reduce the cutting force in the machining of the aluminum alloy used in the aerospace industry. The first part of the thesis deals with problems related to milling technology. The practical part describes the design and construction of prototype cutting tools. Three tools were designed for experimental measurement. The technology of cutting tools made from super hardened cutting materials with laser technology is presented. The experimental part of the thesis is a measurement of the cutting force according to cutting parameters and machined material.
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Changes motor functions in mouse model of cerebellar degeneration in the course of the ontogenesis
Šalomová, Martina ; Jelínková, Dana (advisor) ; Kubik-Zahorodna, Agnieszka (referee)
The cerebellum affects a number of important and complex processes in the organism. It ensures coordination, motor learning and plays an important role in cognitive and affective functions. In the case of cerebellar degeneration, we find not only the movement disorders but also behavioral abnormalities, collectively referred to as cognitive-affective syndrome. The aim of this work was to investigate motor functions during ontogenesis in animal models of hereditary cerebellar degeneration - mutant mice Lurcher and Purkinje cell degeneration using the device for quantitative gait analysis and rotarod. In addition, the effect of physical activity on the extent of ataxia and manifestations in classical behavioral tests was monitored. The results confirmed significant differences in motor skills between mutant and healthy mice; differences were also observed in some gait parameters, especially in walking speed and parameters that correlate with it. The motor functions of most groups of mice did not change during ontogenesis, pcd mice deteriorated their performance on the rotarod. The effect of physical activity was not found, with the exception of Forced swimming test. Physical activity of set intensity did not have any beneficial effect on the motoric manifestations of the mice.
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Analysis of the force loading of the end mills with PCD considering their sharpening
Trčka, Tomáš ; Kalivoda, Milan (referee) ; Polzer, Aleš (advisor)
Measurement of the force loading is a significant type of measurement in mechanical engineering applied to analyse important aspects in the machining process. In addition to the determination of specific material constants, it is possible to analyse, for example, various machining strategies, geometries of tools or the degree of wear of the cutting edges of cutting tools. This master’s thesis deals especially with the last two mentioned aspects which are subjects of an experiment on end mills with PCD inserts sharpened by a different technology. In the introductory part the cutting forces are theoretically analysed along with their measurement possibilities and the technology of the production of the mills including their sharpening – WEDM and EDM-G. One chapter is concerned with the milling of plastic materials, as PVC was the material used for the workpiece during the experiment. The first experimental part is devoted to the analysis of sharpened tools followed by the measurement of forces using the piezoelectric dynamometer and the subsequent analysis of the influence of the different tool geometry. The last conducted experiment monitors how the overall cutting forces of individual end mills sharpened by different technology changed over specific milling time slots.
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