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Determination of thermal conductivity anisotropy of polymeric heatsinks for electronics
Brachna, Róbert ; Kůdelová, Tereza (oponent) ; Komínek, Jan (vedoucí práce)
The master's thesis focuses on creating a numerical model of a polymeric heat sink with emphasis on its significant thermal conductivity anisotropy. This anisotropy is caused by highly thermally conductive graphite filler. Its final orientation is given by the melt flow inside the mould cavity during injection molding. The numerical model is created on the basis of a heat sink prototype subjected to experimental measurements, whose physical conditions are reliably replicated by the model. The determination of anisotropy is divided into two parts. The qualitative part is based on the fracture analysis of the heat sink prototype and determines the principal directions of the conductivity tensor in individual sections of the geometry. The computation of principal conductivities falls into the quantitative part, in which this task is formulated as an inverse heat conduction problem. The input data for the proposed task are experimentally obtained temperatures at different places of the geometry. The values of principal conductivities are optimized to minimize the difference between the measured and simulated temperatures.
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Processing of temperature data for inverse heat conduction tasks
Brachna, Róbert ; Komínek, Jan (oponent) ; Luks, Tomáš (vedoucí práce)
This bachelor's thesis deals with digital filters and noise removal from temperature measurements. The basic concept for the proper understanding of properties of filters is the discrete Fourier transform, which is illustrated on a given example. Next, the thesis considers linear filters and the design of basic types for noise reduction. An adaptive filter is designed by analyzing experimental data. This filter is subjected to further analysis using a simulated cooling process disrupted with artificially added noise and will be compared to other conventional filters. One criterion is to compare the curve of the filtered temperature to the simulated one. The second criterion is the reconstructed boundary condition, which is the output of the inverse heat conduction task.
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Determination of thermal conductivity anisotropy of polymeric heatsinks for electronics
Brachna, Róbert ; Kůdelová, Tereza (oponent) ; Komínek, Jan (vedoucí práce)
The master's thesis focuses on creating a numerical model of a polymeric heat sink with emphasis on its significant thermal conductivity anisotropy. This anisotropy is caused by highly thermally conductive graphite filler. Its final orientation is given by the melt flow inside the mould cavity during injection molding. The numerical model is created on the basis of a heat sink prototype subjected to experimental measurements, whose physical conditions are reliably replicated by the model. The determination of anisotropy is divided into two parts. The qualitative part is based on the fracture analysis of the heat sink prototype and determines the principal directions of the conductivity tensor in individual sections of the geometry. The computation of principal conductivities falls into the quantitative part, in which this task is formulated as an inverse heat conduction problem. The input data for the proposed task are experimentally obtained temperatures at different places of the geometry. The values of principal conductivities are optimized to minimize the difference between the measured and simulated temperatures.
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Processing of temperature data for inverse heat conduction tasks
Brachna, Róbert ; Komínek, Jan (oponent) ; Luks, Tomáš (vedoucí práce)
This bachelor's thesis deals with digital filters and noise removal from temperature measurements. The basic concept for the proper understanding of properties of filters is the discrete Fourier transform, which is illustrated on a given example. Next, the thesis considers linear filters and the design of basic types for noise reduction. An adaptive filter is designed by analyzing experimental data. This filter is subjected to further analysis using a simulated cooling process disrupted with artificially added noise and will be compared to other conventional filters. One criterion is to compare the curve of the filtered temperature to the simulated one. The second criterion is the reconstructed boundary condition, which is the output of the inverse heat conduction task.
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