National Repository of Grey Literature 33 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Influence of temperature on the rock stress distribution and slope stability
Racek, Jonáš ; Blahůt, Jan (advisor) ; Kycl, Petr (referee)
This thesis deals with the influence of cyclic temperature changes on the surface of a rock mass on temperature and stress fields inside the rock slope and their influence on local and overall slope stability. The review part deals with the evolution and stability of rock slopes with a focus on temperature oscillations. Furthermore, thermal parameters of rock masses, rocks and minerals are discussed. In the practical part a 2D numerical linear-elastic model of the response of the rock slope Pastýřská stěna in Děčín to cyclic temperature changes during different periods was developed. It was used to determine the depth of penetration of temperature cycles and the associated changes and redistribution of stresses within the mass and the zones susceptible to mechanical failure of the rock. iii
Theoretical investigation of 27Al chemical shifts dependence on water amount and temperature in zeolite MFI
Willimetz, Daniel ; Grajciar, Lukáš (advisor) ; Blahut, Jan (referee)
Title: Theoretical investigation of 27 Al chemical shifts dependence on water amount and temperature in zeolite MFI Abstract: This bachelor thesis explores 27 Al NMR spectra in zeolite MFI and investigates the impact of several factors on the chemical shielding values, including water loading, temperature, and the relative positions of aluminum pairs. Various machine learning-based methods for calculating chemical shift are evaluated. Molecular dynamics simulations with neural network potentials are used to simulate experimental conditions. Neural network potentials offer a highly efficient means of calculating energy with a significant speed-up of approximately 1000 times faster than density functional theory, while maintaining a high level of accuracy. This study is the first to examine 27 Al NMR under operando conditions, with a focus on the experimentally relevant amount of water. Keywords: 27 Al NMR, machine learning, zeolites, MFI, operando conditions, neural network potentials
Study of optical properties of perovskites and their precursors thin films
Blahut, Jan ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
The thesis is focused on the study of the optical properties of thin films of perovskites and their precursors. The first two chapters of the theoretical part are theoretical introduction to the studied problems, they discuss the basics of electromagnetic radiation and its interaction with matter and basic informations about perovskite materials, especially their semiconductor structure. The remaining two chapters deal with specific principles and practical uses of methods and procedures for the preparation of thin films, as well as the instrumentál characteristics of thin films in terms of their optical properties. The experimental part is focused on the preparation of solutions of perovskites and their precursors, where the replication and optimization of published procedures took place, the preparation of thin layers of these solutions by the spin coating method and their ellipsometric characterization using the Tauc plot method, modeling and fitting of the experimentally determined data, which led to the determination of the index refraction, absorption coefficient and band gap width of individual materials.
Development and validation of a hypoplastic model for soft clays incorporating rate effects and strength anisotropy
Jerman, Jan ; Mašín, David (advisor) ; Blahůt, Jan (referee) ; Hrubešová, Eva (referee)
The thesis presents modelling framework for soft clays. Soft clays typically occur in marine environment, coastal areas and along rivers, soft clay deposits are also associated with the periglacial conditions. Soft clay seabeds are also prevalent in locations used as foundations of various energy sources (renewable and hydrocarbon). Growing world population increased demand for land, and this, consequently, leads to seaward land reclamation for urban development in coastal areas. Thus, construction on soft soil deposits has become increasingly important as soft clays occur in locations of construction projects for city infrastructure. The stress-strain behaviour of soils, especially clayey soils, is well-known to be rate- dependent. This fact is relevant for specific engineering projects, where the long-term performance of constructions is of interest. This is particularly important for soft clays as the very high degree of compressibility in primary compression and during creep makes rate-dependent soil behaviour an important factor for geotechnical problems. Moreover, the slow slope movements of slow-moving landslides and creeping slopes are controlled mostly by shear creep properties of the shear-zone soil and the effective stress state. Thus, for the case of creeping landslide modelling, a...
ANALYSIS OF A SLOPE DEFORMATION OF THE D11 MOTORWAY CUT
Rotová, Petra ; Tábořík, Petr (advisor) ; Blahůt, Jan (referee)
This diploma thesis consists of a research and a practical part. The research part summarises the problem of slopes movements. The practical part deals with the determination of the slope deformation causes, at the 76th km of the D11 motorway. Causes determination was based on laboratory tests of soil samples taken from the disrupted motorway cut, made at PřF UK soil mechanics lab. Tests of grain size composition were done, plasticity of the L 26 sample was determined and critical strength of the reconstituted L26 and L27 samples was found out in the Translational apparatus box. Soils were categorized due to the according standards and the acquired data were evaluated. In the BricsCAD software, a well arranged locality situation and the slope deformation crosscut underlayed with the geophysical ERT cut were illustrated. In the GEO5 software, slope stability models were created using the Spencer Method of Slices. The slip surface and the groundwater level during the disruption were determined. The practical part also covers a proposal of a remediation appropriate for this deformation and it's modelling in GEO5. For the remediation, the slope stability level is determined. The work is based on the specialized literature, articles, research reports and standards. Powered by TCPDF (www.tcpdf.org)
Slope deformations in the Bohemian Paradise - research, typology and conditions of origin
Merlíčková, Soňa ; Hartvich, Filip (advisor) ; Blahůt, Jan (referee)
This thesis deals with occurrence, conditions and character of slope deformations in the Protected landscape area (CHKO) Český ráj. This area is typically formed by sandstones, marls and claystones. Together with tectonic structures and lateral erosion of the Jizera River, they form suitable conditions for slope movements such as rockfall, sliding etc. With help extensive use of the scientific literature, character of study area as well as general conditions for the development of slope movements were described, and their typological classification was established. Next part of the thesis includes the chapters on the methods of research, and a description of the preliminary field research of the model localities. Furthermore, an analysis of causes of the slope movements using the data on climate from the stations of Czech hydro-meteorological institute was performed. Finally, the results are discussed with the referenced sources and conclusions to the topic are formulated. Keywords: CHKO Český ráj, slope movements, slope deformations, tectonics, lateral erosion, land-slide, rockfall, Lužický fault
Regiospecific cyclam derivatives for radiomedical and MRI utilizations
Blahut, Jan ; Kotek, Jan (advisor) ; Drahoňovský, Dušan (referee)
Cyclam (1,4,8,11-tetraazacyclotetradecane) derivatives are widely used for various purposes. In a medicine they are applied as ligands for radiometals applied as diagnostic or therapeutic agents against tumours, hypoxic brain tissues etc. In this thesis a new method for asymmetric cyclam derivati- ves preparation was developed. New cyclam derivatives with trifluoroethyl groups were prepared too. Paramagnetic metal complexes with these fluori- nated ligands can be used as contrast agents for 19 F-MRI. Keywords: Cyclam; Non-symmetric protection; Contrast agents; Trifluoroethylamines; Paramagnetic relaxation; 19 F-MRI.
Dynamics of paramagnetic complexes observed by Nuclear Magnetic Resonance
Blahut, Jan ; Hermann, Petr (advisor) ; Botta, Mauro (referee) ; Dračínský, Martin (referee)
In this Thesis, structure and dynamics of paramagnetic complexes for medical application are studied by Nuclear Magnetic Resonance (NMR). It focuses mainly on development of contrast agents (CA) for Magnetic Resonance Imaging (MRI) which is one of the most effective radiodiagnostic method nowadays. Most of the MRI CAs contains paramagnetic complexes of d- and f-metal ions. The presence of unpaired electron in proximity of NMR active nuclei has two main effects: paramagnetically induced shift and paramagnetically induced relaxa- tion. Both processes can dramatically change the NMR spectrum and often make it unobservable at all. Nevertheless, in many cases, acquisition of such spectra is possible and sometimes even less time-consuming than observation of diamag- netic molecules. Enhanced T1 relaxation allows faster pulse sequence repetition and increased chemical shift dispersion may lead to resolution of originally over- lapped signals. Moreover, the analysis of paramagnetic effects can provide useful information about the structure and dynamics of the studied system. Theoretical background of these effects is described in the Introduction of the Thesis. In the first part of Discussion in the Thesis, a new class of contrast agents for 19F-MRI based on nickel(II) and cobalt(II/III) ions is introduced...
Bifunctional ligands for copper(II) complexation
Blahut, Jan ; Kotek, Jan (advisor) ; Svoboda, Jan (referee)
Because of an indisputable pharmacological advatages of radiometal-labeled compounds, a purpose of this work it to design and synthesize a new chelatation system for copper(II) complexation. The solution properties of the ligand and copper complex are also studied, as well as its ability for binding a targeting molecule.
Use of rock mass classifications for rock fall susceptibility analysis in the conditions of the Bohemian Massif
Racek, Jonáš ; Blahůt, Jan (advisor) ; Petružálek, Matěj (referee)
This thesis deals with rock mass classification systems. The aim of the thesis is to describe and compare selected systems and evaluate their possible use in the Bohemian Massif for assessing the stability of the rock slopes in relation to their susceptibility to rock falls. A part of the thesis deals with rock falls and basic mechanical characteristics of a rock mass. Further on, the thesis describes selected classification systems, specifically RQD, RSR, RMR, SMR, Q-system, Q-slope, GSI, RSR-PR and QTS. These systems were then used for evaluation of stability of rock slopes on three geologically different locations of the Bohemian Massif. information from measurement in field and processing of measured data was used for assessing for possible use of each classification system.

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2 Blahút, Jozef
12 Blahůt, Jan
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