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Measuring magnetic properties of environmental samples
Zárubová, Alžběta ; Petrovský, Eduard (advisor) ; Kapička, Aleš (referee)
A. Zárubová: Měření magnetických vlastností environmentálních vzorků 1 ENGLISH ABSTRACT This bachelor's thesis presents briefly principles and examples of applications of magnetic measurements in environmental studies. Environmental magnetism is based on determination of iron oxides, their content, concentration and grain size. This information can be interpreted in terms of particle origin, transport or diagenesis. The results can provide information on, e.g., climatic changes in the past, short-term events influencing our environment (e.g., volcanic eruptions) or about contemporary problems associated with human activity (environmental pollution). In the last case, environmental magnetism does not intend to replace geochemical methods, but the main aim is to provide fast and easily available additional information, which helps us to be more effective in mapping contaminated areas, monitoring progression of pollution or modeling transport processes of contaminants. Magnetometry is currently intensively used for mapping contamination of atmosphere, soils and sediments; it can be used in defining long-term levels of contamination, individual pollution sources and their contribution to the overall pollution. This thesis provides a brief overview of the physical basics of environmental magnetism and examples...
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Ferroelectrics in an electric field
Pavelka, Petr ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The submitted thesis describes characteristics and use of ferroelectric materials which find their utilization in electrotechnical and electronics industry. The thesis is mainly aimed at their behaviour in the electrical field at various intensity. The method using an osciloscope is selected for measuring. For the main measuring in part of this thesis was produced experimental wafer with five samples which were subsequently mesuared. The VEE PRO program was used for creating of collecting datas for histeresis loop and it’s functionality was checked on wafer with five examples in measuring. During this measuring was also measured electric tension dependence of components of complex permittivity.
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Fluxmeter with graphical display of B-H curve
Ježek, Jaroslav ; Mačák, Jaromír (referee) ; Hanák, Pavel (advisor)
This work deals with simple fluxmeter which is able, together with other device, to show hysteresis loop. Hysteresis loop is a graphic expression of dependence of magnetic induction on intensity of magnetic field. Oscilloscope is used to display the hysteresis loop. This device is fully sufficient for the display. The measured objects are solenoids from various kinds of materials with the same shape. The main aim of this work is the design, realization and description of the fluxmeter. The fluxmeter consists of several partial blocks. The first one, on which this work is focused, is signal generator which is able to generace different kinds of signal. The generated signal comes on primary winding of solenoid where a magnetic field on a given intensity rises. An amplifier is used to obtain the sufficient intensity. Next thing this work is focused on is the design of the integrator which is necessary for the correct function of the fluxmeter. As suggested, there is shown the block diagram of linking of individual parts. There are described the measured results at the end of this work.
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Assesment of stress strain response during cyclic loading
Lehnert, Ondřej ; Slámečka, Karel (referee) ; Horníková, Jana (advisor)
This bachelor´s thesis is focused on assessment of data extracted from testing machine and establishment of cyclic stress-strain curve using peaks of saturated hysteresis loops. In this thesis before data analysis itself, is written down research study about general fatigue of material, then the study is focused on change of mechanical attributes, description of hysteresis loops and cyclic curve. After that follows the procedure of data analysis extracted from testing machine aimed to compare cyclic curve with tensile curve and its mathematical description.
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