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New approaches in higt-resolution shallow seismic prospection
Valenta, Jan ; Dohnal, Jiří (advisor) ; Rudajev, Vladimír (referee) ; Bárta, Jaroslav (referee)
This work deals with the application of seismic methods in high-resolution near-surface prospection. Two topics are covered in this text. The first one describes processing and application of 3D shallow seismic refraction, while the second one deals with possible methods of identification and filtration of S-waves. The processing of the 3D seismic refraction data is currently carried out mainly by means of the seismic tomography. Because the tomography method usually works with the gradient model of the subsurface, an approach to the layer-based model was sought. The solution was found in a modification of the time-term method. The time- term method was modified to handle also the lateral variations of velocity in highly heterogeneous media. REFRACT3D computer program for data processing using the time-term method was developed. The modified time-term method was successfully tested during the archaeological prospection of the Děvin Castle and during the pro- spection of the shallow subsurface of the Ostaš seismic station. The results from the time-term method were compared with the results obtained by the first arrival travel time tomography. In the case of the Děvin Castle the time-term results surpass the tomography one, while at the locality of Ostaš the tomography results are better. The imaging...
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Advanced spectroscopic characterization of quantum dot ensembles
Greben, Michael ; Valenta, Jan (advisor) ; Linnros, Jan (referee) ; Vácha, Martin (referee)
Title: Advanced spectroscopic characterization of quantum dot ensembles Author: Michael Greben Department: Department of Chemical Physics and Optics Supervisor of the doctoral thesis: Prof. Jan Valenta, Ph.D. Abstract: Semiconductor quantum dots (QDs) are small crystallites whose sizes (of the order of nm) cause spatial confinement of carriers in all 3 dimensions. As result, QDs often reveal very different physical properties in comparison with their bulk counterparts. From the optical point of view, the broadening of bandgap with QD-size shrinking is particularly interesting. It is a purely quantum mechanical effect that results from quantum confinement (QC), i.e. dimensional limitations of excitons. A strong spatial confinement leads to a relaxation of momentum (Heisenberg uncertainty principle), consequently, larger overlap of the wave-functions of carriers results in significant increase of probability of radiative recombination. Therefore ensembles of QDs are promising candidates for new generations of photonic and photovoltaic devices. This PhD thesis is primary focused on detailed spectroscopic characterization of ensembles of direct (PbS) and indirect (Si) semiconductor QDs in both colloidal (toluene) and matrix-embedded (oxide or oxinitrides multilayers) forms. The oleic- acid capped PbS QDs were...
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4D Characteristics of Electric Resistivities and Elastic Parameters of Crystalline Rock Massif
Jirků, Jaroslav ; Vilhelm, Jan (advisor) ; Hartvich, Filip (referee) ; Valenta, Jan (referee)
6 Abstract (ENG) The thesis deals with the use of geophysical methods for non-invasive monitoring of geological processes occurring in crystalline massifs. Such a methodology can be used, for example, in monitoring the processes in future and existing deep geological repositories. The main geophysical methods monitoring changes in the rock mass are multielectrode electrical resistivity tomography (ERT) and high-frequency seismics. Monitored parameters that change over time are the apparent electrical resistivity and parameters of excited elastic waves. Based on long-term measurements at the field bases, changes in the rock mass are described. Interpretations of such changes are made using our own laboratory measurements quantifying the effect of groundwater saturation of samples and the effect of sample disruption (mechanical / thermal) on their electrical resistivity. With respect to modelling and interpretation of the apparent resistivity cross-sections the sensitivity function calculation was proposed and carried out in the geometry of used field layout. It was proven that seismic transmission may be carried out in an underground work reliably for long time. Seismic measurement shows that in the environment of underground works excavated decades ago, we practically do not observe any changes in the...
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Separation of induced and remanent sources of magnetic anomalies on the Moon
Vávra, Ondřej ; Kletetschka, Günther (advisor) ; Valenta, Jan (referee)
During every full Moon our natural satellite passes through the Earth's magnetotail. For about 6 days the moon is exposed to a much stronger magnetic field, which induces magnetization in the paramagnetic and ferromagnetic minerals.. I'm trying to find a trace of these minerals in orbital magnetometric data and suggest a new way of analysing the magnetometer data suited for finding iron deposits. In the theoretical part of this work, I presented basic concepts of magnetism, described the magnetosphere, focusing on the dynamic nature of the magnetotail, which is directly influenced by the interaction of the magnetosphere with the fast moving particles of the solar wind. In the computational part, I plotted maps of the magnetometric data from the satellite Kaguya (SELENE) for times in which the Moon is in the Earth's magnetotail and reference maps from times in which the Moon is in the interplanetary magnetic field. I subtracted the data thus making a plot of the induced anomalies. I managed to confirm the occurrence of one of the anomalies in two separate magnetotail events. The induced anomaly located on the northern rim of the South Pole - Aitken Basin likely shows a signature of significant iron deposits.
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Advanced spectroscopic characterization of quantum dot ensembles
Greben, Michael ; Valenta, Jan (advisor)
Title: Advanced spectroscopic characterization of quantum dot ensembles Author: Michael Greben Department: Department of Chemical Physics and Optics Supervisor of the doctoral thesis: Prof. Jan Valenta, Ph.D. Abstract: Semiconductor quantum dots (QDs) are small crystallites whose sizes (of the order of nm) cause spatial confinement of carriers in all 3 dimensions. As result, QDs often reveal very different physical properties in comparison with their bulk counterparts. From the optical point of view, the broadening of bandgap with QD-size shrinking is particularly interesting. It is a purely quantum mechanical effect that results from quantum confinement (QC), i.e. dimensional limitations of excitons. A strong spatial confinement leads to a relaxation of momentum (Heisenberg uncertainty principle), consequently, larger overlap of the wave-functions of carriers results in significant increase of probability of radiative recombination. Therefore ensembles of QDs are promising candidates for new generations of photonic and photovoltaic devices. This PhD thesis is primary focused on detailed spectroscopic characterization of ensembles of direct (PbS) and indirect (Si) semiconductor QDs in both colloidal (toluene) and matrix-embedded (oxide or oxinitrides multilayers) forms. The oleic- acid capped PbS QDs were...
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Sociological aspects of translation norms in legal environments
Valenta, Jan ; Králová, Jana (advisor) ; Ježková, Slavomíra (referee)
This thesis paper attempts to discover the processes used to set up and negotiate translation norms in legal environments. It is based on the existing theoretical knowledge of legal translation and on the theoretical works on translation norms, especially the works by Gideon Toury, Theo Hermans, Andrew Chesterman and other authors. The aim of this thesis paper is to confront these theories with the every-day experiences of translating in legal environments. The research method used for this purpose is qualitative sociological research - a combination of the analytical procedures of grounded theory first drafted by Strauss and Glaser and data collection procedures based on "problem-centered interviews" and on the investigation of documents. The total of 10 respondents - translators who work or have worked in law firms - have participated in the survey. Legal translation is very specific in terms of the processes whereby translation norms are set up and negotiated. The key issue is the issue of liability. Translators employed in law firms are not liable for the final wording of the translation - it is the lawyer who is held liable for the translation that forms a part of his or her legal service or advice. This influences the mutual relations between the translator and the lawyer who plays the role of the...
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Geophysical exploration of supposed maar volcanoes in Western Bohemia
Turjaková, Veronika ; Valenta, Jan (advisor) ; Skácelová, Zuzana (referee)
We were investigating two localities of supposed maar volcanoes, Ztracený rybník and Bažina, which can be found at the western margin of the Eger rift on the presumed line of the Tachov fault. The Eger rift was abundant in volcanic activity during Tertiary and still is a seismoactive zone with distinct post- volcanic features. The examined structures are distinct morphological depressions (ca. 30 m deep and several hundreds meters wide) with a circular shape which is characteristic for maar structures. We studied the locality using a complex of geophysical methods: a ground magnetometry, electric resistivity tomography and a time-domain electromagnetic sounding. The results showed a circular rim of high resistivities around the depressions and approximately 100 m of sediments filling the depression. Moreover, we have mapped a negative magnetic anomaly in the lesser of these two structures (Bažina) indicating a basic intrusion that got close to the surface. Moreover, we have observed the intrusion on the resistivity data as well. Therefore, we can suggest that these two structures are diatremes created during the phreatomagmatic eruption. The lesser maar (Bažina) erupted during the reversed geomagnetic field.
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Nanoscopy, spectroscopy and modication of individual nanoobjects in liquid environment
Smísitel, Petr ; Valenta, Jan (advisor) ; Galář, Pavel (referee)
In this diploma thesis we will study the luminescence properties of nanocrystals. We will summarize the basic division according to size and standard method of theoretical description of semiconductor and metal nanocrystals. We will describe the luminescence properties of nanocrystals and the influence of the surrounding environment. In the se- cond part of the thesis we will follow up the construction of an apparatus for imaging luminescence spectroscopy intended for the measurement of individual nanoobjects in a liquid environment. Finally, we will study luminescence properties of organixally passi- vated metal clusters in a liquid environment with changes in temperature and excitation intensity. We compare the luminescence of gold nanocrystals with and without long po- lyethylene glycol chains bound on the surface. 1
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Time-domain electromagnetics and its applications for prospection of maar volcanoes
Fait, Václav ; Valenta, Jan (advisor) ; Klanica, Radek (referee)
In this work I study the advanced geophysical method - the time domain electromagnetics. In the theoretical part I summarize principles of the method, describe several measuring systems and guide the reader through the software for data processing. I further prove reliability of the applied methodology by forward and inverse computations for a simplified model of supposed target structures. The results show that for the selected configuration of field measurements with a depth range of 100-200 m the influence of 3D structures is significant when placed in a distance smaller than approximately 100 m. In the practical part I test the method in the sedimentary environment and find that results of the method are in accordance with the vertical electrical sounding method. Subsequently, I show that the artificial highly conductive object placed inside the current loop significantly affects the outcomes of the method. Artificial conductive object has only minute effect if placed in a close distance but outside of the current circuit. Besides the theoretical and experimental findings about the reliability of the method I have applied the method for research of maar volcanoes. I have confirmed with high probability the presence of maar volcano near the Jablonná village. The results measured close to the...
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Robotized workplace for palletizing parts
Valenta, Jan ; Bražina, Jakub (referee) ; Vetiška, Jan (advisor)
The subject of this thesis are robotic palletizing workplaces, which are theoretically analyzed ind the research part. In practical part of this thesis, these findings are used to design a specific robotic workplace. Thereafter, this design is developed in order to acquint the reader with each part of workplace. Subsequently the workplace is digitally commissioned. The result of this thesis is fully functional CAD model of the workplace with program ready to be uploaded to the robot.
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