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Assessment of defects and faults of ETICS Systems
David, Jan ; Láník, Jaromír (referee) ; Schmid, Pavel (advisor)
This diploma thesis discusses the problems of defects and faults of external thermal insulation composite systems. The first part describes the correct procedures for application systems, the next part describes defects, faults and their causes and the end of the thesis describes the contactless diagnostic methods used for the survey of ETICS. This part is mainly focus on detection of anchors. The example shows the calculation of anchoring.
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Improving friction of lubricated contacts by modifying thermal conductivity
Šnevajs, Matěj ; Hartl, Martin (referee) ; Šperka, Petr (advisor)
This thesis deals with an experimental study regarding the effects of the thermal conductivity of contact bodies on the friction, lubricant film thickness and temperature distribution in EHL contact. The thesis focuses on the configuration of the ball on disc contact. The contact body materials are characterized by a wide range of thermal properties. New contact pairs are proposed and used in the study in order to make the contact bodies’ thermal properties dependent on the behaviour of EHL contact. The colorimetric interferometry method is used to measure the lubricant film thickness and the infrared thermography method is used to observe the temperature distribution in EHL contact. The author presents the assumed mechanism of heat transfer within EHL contact on the basis of different heat transfer mechanisms. The same conditions – such as the Hertz pressure, mean entrainment speed, sliding speed and ambient temperature – are induced for all the contact pair combinations. That is why the differences in the results are attributed to the different thermal phenomena in the contact, caused by the thermal properties of the contact bodies. In the case of contact bodies with a reduced heat dissipation capability, a reduction of the friction coefficient of up to 50 % is observed, which is attributed to an increase in the lubricant temperature, resulting in a decrease in its viscosity. This is confirmed by the infrared thermography method, whereby a significantly higher lubricant temperature is observed in the case of a combination of contact materials with a lower heat dissipation capability.
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Contactless temperature measurement in sliding contacts
Knoth, Tomáš ; Hajžman, Michal (referee) ; Omasta, Milan (advisor)
This work deals with the implementation of infrared thermography for detailed temperature mapping in conformal sliding contacts in a pin-on-disc configuration. The implemented method is then applied for study of textured sliding contacts. This method can bring unique insights into the temperature distribution in contacts with textured surfaces, where thermal phenomena play a crucial role. The current state of knowledge in this area relies mainly on numerical simulations, which is why the absence of experimental knowledge is a fundamental gap in knowledge. The research questions are devoted to the temperature distribution in contact and the demonstration of the occurrence of the so-called viscosity wedge effect. Hypotheses are built on the basis of works that study the issue using numerical simulations. The implementation of the method is based on the calibration and measurement procedure from the area of point contacts, where the ball-on-disc configuration is used. This method of calibration was confronted with applications on conformal textured surfaces and subsequently modified according to identified needs. In the second part of the work, contacts with textured surfaces are analyzed using the implemented method. The subject of interest here is parallel and near-parallel contacts. On the correction of the Stribeck curve according to the actual temperature of the lubricant, it is demonstrated that knowledge of the actual temperature of the lubricant in contact is essential for its study. However, the occurrence of thermal phenomena could not be proven in the range of experimental conditions.
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Application of thermography in the diagnostics of transport infrastructure objects
Janků, Michal ; Stryk, Josef
In order to maintain the proper condition of buildings, bridges, roads and other structures, their regular maintenance is essential. Often, if the distress is detected at the beginning of the disorder, the cost of removing it is far lower than after months of uncontrolled degradation. Locating a distress in time, often means detecting it before it is visible to the naked eye. A key means of detecting hidden distresses is non-destructive diagnostic methods (NDT), including thermographic testing. The purpose of the presented methodology is to provide an efficient tool that will allow a rapid assessment of the state of the transport infrastructure objects and help with the identification of the locations where visual inspection or detailed diagnosis is required. The thermographic measurement is non-contact and can be carried out without the need to exclude traffic on the road. The methodology describes possible ways of using infrared thermography, especially in diagnosis of bridges, roads and tunnels. The presented methodology was prepared within project TE01020168 - Centre for Effective and Sustainable Transport Infrastructure (CESTI), with financial support of the Czech Technology Agency within the Centre of Competence Program. This methodology is intended for road managers at all levels (state, county, city), designers, construction companies and other entities that can use data and processed outputs from thermographic measurements.
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Improving friction of lubricated contacts by modifying thermal conductivity
Šnevajs, Matěj ; Hartl, Martin (referee) ; Šperka, Petr (advisor)
This thesis deals with an experimental study regarding the effects of the thermal conductivity of contact bodies on the friction, lubricant film thickness and temperature distribution in EHL contact. The thesis focuses on the configuration of the ball on disc contact. The contact body materials are characterized by a wide range of thermal properties. New contact pairs are proposed and used in the study in order to make the contact bodies’ thermal properties dependent on the behaviour of EHL contact. The colorimetric interferometry method is used to measure the lubricant film thickness and the infrared thermography method is used to observe the temperature distribution in EHL contact. The author presents the assumed mechanism of heat transfer within EHL contact on the basis of different heat transfer mechanisms. The same conditions – such as the Hertz pressure, mean entrainment speed, sliding speed and ambient temperature – are induced for all the contact pair combinations. That is why the differences in the results are attributed to the different thermal phenomena in the contact, caused by the thermal properties of the contact bodies. In the case of contact bodies with a reduced heat dissipation capability, a reduction of the friction coefficient of up to 50 % is observed, which is attributed to an increase in the lubricant temperature, resulting in a decrease in its viscosity. This is confirmed by the infrared thermography method, whereby a significantly higher lubricant temperature is observed in the case of a combination of contact materials with a lower heat dissipation capability.
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Plasma Heat Flux to Solid Structures in Tokamaks
Vondráček, Petr ; Horáček, Jan (advisor) ; Gunn, James P. (referee) ; Svoboda, Vojtěch (referee)
Plasma Heat Flux to Solid Structures in Tokamaks Petr Vondráček Energy and particle exhaust is the key issue for future fusion reactors based on magnetic plasma confinement, namely for tokamaks. Good understanding of processes controlling plasma heat fluxes impinging the first wall of tokamaks is of a main concern for fusion research. This doctoral thesis is focused on experimental investigation of plasma heat fluxes in different locations of the COMPASS tokamak. A new infrared thermography system was built for this purpose as a part of this PhD research. There are four main topics studied using the system. First of all, a narrow near-SOL heat flux channel with a very steep radial profile is characterised in HFS limited discharges. It is shown that the near-SOL heat flux decay length is consistent with the drift-based model of the SOL heat transport. Secondly, heat loading of leading edges of misaligned limiters is broadly studied. The optical approximation of the heat flux distribution around a poloidal leading edge is confirmed as a valid approach. Heat loading of a magnetically shadowed side of a toroidal limiter gap is observed experimentally for the first time confirming predictions of particle-in-cell code simulations. Thirdly, localised hot-spots caused by the impact of runaway electrons as well as...
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Methods of detection of fungal diseases applicable in plant phenotyping and remote sensing
Klem, Karel ; Veselá, Barbora ; Holub, Petr ; Urban, Otmar ; Mezera, J.
This methodology summarises findings from a comparison of three perspective methods of fungal disease detection applicable for remote sensing and plant phenotyping of fungal disease resistance. These methods are spectral reflectance, infrared thermal imaging, and blue-green fluorescence imaging. On the example of winter wheat infection with powdery mildew, stripe rust and brown rust the strengths and weaknesses of individual methods were demonstrated. From these results it is evident that all three methods are potentially applicable for non-destructive fungal disease detection, but their practical use may vary. Testing of spectral reflectance indices for the detection of fungal diseases showed particularly the high detection reliability of the red-edge and green band based spectral vegetation indices. Infrared thermal imaging has shown high detection accuracy for powdery mildew and brown rust, but lower for stripe rust. Blue-green fluorescence and thermal imaging seems to be also a very promising tools for evaluating the intensity and spatial distribution of infection on a leaf level.
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Assessment of defects and faults of ETICS Systems
David, Jan ; Láník, Jaromír (referee) ; Schmid, Pavel (advisor)
This diploma thesis discusses the problems of defects and faults of external thermal insulation composite systems. The first part describes the correct procedures for application systems, the next part describes defects, faults and their causes and the end of the thesis describes the contactless diagnostic methods used for the survey of ETICS. This part is mainly focus on detection of anchors. The example shows the calculation of anchoring.
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Possibilities of nondestructive diagnostics of ETICS
Zvěřina, Aleš
Article deals with possibilities of nondestructive diagnostics of exthernal thermal inulation systems (ETICS) and compares possibilities of 3 used and researched methods. Infrared thermography, which is one of most used method, impedance defectoscopy, a method, which has been used for investigating of flat roof for 3 years and radar diagnostics, using for reverse reconstruction of anchor plans of ETICS. A special focus is dedicate to impedance defectoscopy, becouse the results of this method is possible to display clearly as results on thermograms from infrared thermography.
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