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Application of Electromagnetic and Acoustic Emission for the Diagnostics of Advanced Composite Materials
Trčka, Tomáš ; Chobola, Zdeněk (referee) ; Lokajíček,, Tomáš (referee) ; Koktavý, Pavel (advisor)
The subject of this dissertation is a theoretical and experimental study of electromagnetic and acoustic emission generated in the course of crack formation in solid dielectric materials. Theoretical part of this work is focused on the electromagnetic emission method, because it is related to a number of unsolved problems in the field of generated emission signals measurement, as well as in the field of the correct interpretation of obtained experimental data. Consequently, issues of emission signals detection by capacitance sensors and the transformation of crack primary parameters on the measured variables within the proposed transfer system have been dealt with. The results in this area were an extension of application range of the electromagnetic emission method on composite materials (especially on fiber reinforced polymer composites), identification and evaluation of the most significant emission sources in investigated composites and developing a methodology for evaluating of the crack primary parameters based on the measured emission signals waveforms in time and frequency domain. The experimental part of this dissertation was focused on a complex methodology for emission signals (including data from additional sensors) continual recording, processing and evaluation and for monitoring the response of stressed material to an applied mechanical load in real-time. Partial results from different research areas were also implemented into this methodology. This included the detection of emission signals, design and implementation of the appropriate measuring apparatus, analysis of measured signals in the time and frequency domain and advanced methods for processing and evaluation of measured data.
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Design and set up of a laboratory sample of a laser deflectometer for measurement of mechanical stress within thin films
Šustek, Štěpán ; Klapetek,, Petr (referee) ; Ohlídal, Miloslav (advisor)
This diploma thesis describes the design of a device for measuring stress in thin films – laser deflectometer, realization of its design and its experimental testing. The thesis is divided into five chapters. The first chapter deals with the stress in thin films and its influence on substrate – thin film system. The second chapter provides an overview of devices widely used for measuring stress in thin films and describes some their advantages and disadvantages. In the third chapter some design possibilities of the device are presented. The final solution of device called deflectometr is introduced in the fourth chapter. The last chapter includes the functional testing the device.
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Modern methods for Chip Attach
Nešpor, Dušan ; Novotný, Marek (referee) ; Szendiuch, Ivan (advisor)
The work deals with packaging and die attach issues. The general aim of this investigation is thermomechanical stress between package and substrate depending on different thermal and mechanical properties of used materials. Work contains modeling with program ANSYS and practical tests with testing packages. Determining a place in the solder with the maximal and the minimal stress values and determining of the stress distribution for all materials are the results of this research.
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Mechanical durability of waterproofing membranes against elements of waterproofing membrane construction protection
Remeš, Josef ; Oláh,, Jozef (referee) ; Novotný,, Marek (referee) ; Novotný, Miloslav (advisor)
Waterproofing membranes are one of the most commonly used waterproofing insulation materials. These can be found both in assemblies of roof constructions and substructures and are a key component for waterproofing systems. During design process it is necessary to select materials, elements and accessories so that mutual compatibility, waterproof effectiveness and reliability is ensured. In order to protect the main waterproofing layer a composition is therefore completed with construction protection elements, which are meant to prevent from a mechanical damage of waterproofing membrane. Mechanical stress and damage may become evident in variety of situations, which can be caused externally not only as an inappropriate ground bashing procedure but also as a consequence of improper waterproofing construction protection. In practice there are many cases of waterproofing system failures due to stress of elements with higher mechanical durability which affect elements with lower mechanical durability. The dissertation deals with an application of dimpled membranes protected by the layer of waterproofing membranes, which may due to stress and mutual compatibility result in waterproofing system failure and waterproofing reliability decrease. The dissertation is focused on mechanical durability of waterproofing membranes made of folio and modified bitumen membrane against damage from dimple membrane depending on stress category. First, possible waterproofing membrane damage from dimple extrusion is calculated and evaluated. The next part deals with verifying by experiment based on an effect of long-term static stress and short-term dynamic stress caused by ground bashing, where a measurement of ground bashing stress is performed. Experiment interpretation and an acquired knowledge provided the dissertation with an information what combination and order of particular layers results in higher risk of waterproofing system failure and waterproofing reliability decrease
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Mechanical and Electrical Properties of Microcrystalline Silicon Thin Films
Vetushka, Aliaksei ; Fejfar, Antonín (advisor) ; Čech, Vladimír (referee) ; Sládek, Petr (referee)
Amorphous and nano- or micro- crystalline silicon thin films are intensively studied materials for photovoltaic applications. The films are used as intrinsic layer (absorber) in p-i-n solar cells. As opposed to crystalline silicon solar cells, the thin films contain about hundred times less silicon and can be deposited at much lower temperatures (typically around 200 0 C) which saves energy needed for production and makes it possible to use various low cost (even flexible) substrates. However, these films have a complex microstructure, which makes it difficult to measure and describe the electronic transport of the photogenerated carriers. Yet, the understanding of the structure and electronic properties of the material at nanoscale is essential on the way to improve the efficiency solar cells. One of the main aims of this work is the study of the structure and mechanical properties of the mixed phase silicon thin films of various thicknesses and structures. The key parameter of microcrystalline silicon is the crystallinity, i.e., the microcrys- talline volume fraction. It determines internal structure of the films which, in turn, decides about many other properties, including charge transport and mechanical sta- bility. Raman microspectroscopy is a fast and non-destructive method for probing the...
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The role of p130CAS in mechanosensing
Braniš, Jaroslav ; Brábek, Jan (advisor) ; Gregor, Martin (referee)
Sensing mechanical stimuli by proteins and their conversion into biochemical signals in a mechanotransduction is the recently discussed topic in cell biology. The main molecules that cells use to sense mechanical stimuli, are membrane proteins that transmit the mechanical stimulus into the cell. In the cell are found protein complexes, which transmit the signal further. One of the most important protein that has the ability to change the mechanical stimuli to biochemical signals and transmit them to other protein is p130Cas. This work deals with the ability of p130Cas to sense mechanical stimuli and transmit them to other proteins and signaling pathways that regulate cellular response depending on the mechanical stress. Key words: p130Cas, p130Cas/Crk komplex, mechanical stress
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Mechanical durability of waterproofing membranes against elements of waterproofing membrane construction protection
Remeš, Josef ; Oláh,, Jozef (referee) ; Novotný,, Marek (referee) ; Novotný, Miloslav (advisor)
Waterproofing membranes are one of the most commonly used waterproofing insulation materials. These can be found both in assemblies of roof constructions and substructures and are a key component for waterproofing systems. During design process it is necessary to select materials, elements and accessories so that mutual compatibility, waterproof effectiveness and reliability is ensured. In order to protect the main waterproofing layer a composition is therefore completed with construction protection elements, which are meant to prevent from a mechanical damage of waterproofing membrane. Mechanical stress and damage may become evident in variety of situations, which can be caused externally not only as an inappropriate ground bashing procedure but also as a consequence of improper waterproofing construction protection. In practice there are many cases of waterproofing system failures due to stress of elements with higher mechanical durability which affect elements with lower mechanical durability. The dissertation deals with an application of dimpled membranes protected by the layer of waterproofing membranes, which may due to stress and mutual compatibility result in waterproofing system failure and waterproofing reliability decrease. The dissertation is focused on mechanical durability of waterproofing membranes made of folio and modified bitumen membrane against damage from dimple membrane depending on stress category. First, possible waterproofing membrane damage from dimple extrusion is calculated and evaluated. The next part deals with verifying by experiment based on an effect of long-term static stress and short-term dynamic stress caused by ground bashing, where a measurement of ground bashing stress is performed. Experiment interpretation and an acquired knowledge provided the dissertation with an information what combination and order of particular layers results in higher risk of waterproofing system failure and waterproofing reliability decrease
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The role of p130CAS in mechanosensing
Braniš, Jaroslav ; Brábek, Jan (advisor) ; Gregor, Martin (referee)
Sensing mechanical stimuli by proteins and their conversion into biochemical signals in a mechanotransduction is the recently discussed topic in cell biology. The main molecules that cells use to sense mechanical stimuli, are membrane proteins that transmit the mechanical stimulus into the cell. In the cell are found protein complexes, which transmit the signal further. One of the most important protein that has the ability to change the mechanical stimuli to biochemical signals and transmit them to other protein is p130Cas. This work deals with the ability of p130Cas to sense mechanical stimuli and transmit them to other proteins and signaling pathways that regulate cellular response depending on the mechanical stress. Key words: p130Cas, p130Cas/Crk komplex, mechanical stress
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Mechanical and Electrical Properties of Microcrystalline Silicon Thin Films
Vetushka, Aliaksei ; Fejfar, Antonín (advisor) ; Čech, Vladimír (referee) ; Sládek, Petr (referee)
Amorphous and nano- or micro- crystalline silicon thin films are intensively studied materials for photovoltaic applications. The films are used as intrinsic layer (absorber) in p-i-n solar cells. As opposed to crystalline silicon solar cells, the thin films contain about hundred times less silicon and can be deposited at much lower temperatures (typically around 200 0 C) which saves energy needed for production and makes it possible to use various low cost (even flexible) substrates. However, these films have a complex microstructure, which makes it difficult to measure and describe the electronic transport of the photogenerated carriers. Yet, the understanding of the structure and electronic properties of the material at nanoscale is essential on the way to improve the efficiency solar cells. One of the main aims of this work is the study of the structure and mechanical properties of the mixed phase silicon thin films of various thicknesses and structures. The key parameter of microcrystalline silicon is the crystallinity, i.e., the microcrys- talline volume fraction. It determines internal structure of the films which, in turn, decides about many other properties, including charge transport and mechanical sta- bility. Raman microspectroscopy is a fast and non-destructive method for probing the...
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