National Repository of Grey Literature 15 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
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.
3D reconstruction of abandonned ponds using UAV photogrammetry
Stanovský, Tomáš ; Langhammer, Jakub (advisor) ; Blahůt, Jan (referee)
The main focus of the thesis is the reconstruction of 3D models and digital elevation models of five abandoned splash dams in Roklanský brook catchment using UAV photogrammetry methods. The aim of this work is to compare accuracy of the models with available conventional data sources and historical sources. Parallel topic is the research of accuracy of the models created through UAV methods and application of retention potential of small water reservoirs, in headwater areas. The images were taken with a drone-mounted camera. Modelling was done by processing images in software Agisoft PhotoScan through a workflow process, dense point cloud classification and subsequent DEM interpolation. Subsequent delineation of reservoirs retention space, altimetry correction and bathymetric analysis was performed in ArcMap over the interpolated DEM. The results and discussion point to the benefits and limitations of UAV methods, especially to altimetric accuracy of the resulting models relative to conventional DMR5G data and bathymetric characteristics derived from the models. Keywords: UAV; DEM; retention; GIS; model; pond
Dynamics of paramagnetic complexes observed by Nuclear Magnetic Resonance
Blahut, Jan
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...
Landslide susceptibility analysis of Czechia
Racek, Ondřej ; Blahůt, Jan (advisor) ; Klimeš, Jan (referee)
In geosciences modelling is rather quickly developing discipline. Statistical modelling of landslide susceptibility is relatively more traditional approach. Nevertheless, more complicated statistical methods are being developed and applied on larger areas. This development is caused especially by increasing computational capacity and software. This diploma thesis summarises existing statistical landslide susceptibility modelling approaches. In the following part, several landslide susceptibility models were created for the area of Czechia. These models were created using logistic regression, naive Bayes and artificial neural network (ANN). Additionally, two more models were created using expert driven approach. All models were made using thirteen conditioning factors, i.e.elevation, slope, engineering geological regions, climatic areas, mean annual precipitation, topographic wetness index (TWI), aspect, orogenetic class, distance from confirmed fault, distance from watercourse, internal relief, land cover and slope shape. Models driven by statistical approach were created using Orange software. Landslide inventories that were used for construction of all models are based on two databases: "Registr svahových nestabilit" and "Registr sesuvů-Geofond". Using validation by SRC, PRC and ROC curves...
Stability of volcanic islands in relation to giant landslides on the example of El Hierro island, Canary Islands
Olejár, Filip ; Blahůt, Jan (advisor) ; Novotná, Ivona (referee)
Title: Stability of volcanic islands in relation to giant landslides on the example of El Hierro Island, Canary Islands Volcanic islands are known by common occurrence of volcano collapses usually connected with their early stage of formation. When this type of slope deformation occurs, large masses of material, often exceeding hundreds of thousands of cubic meters of rocks, are moving downslope. The development of this kind of movements is firmly linked with the period of volcanic islands growth. Nowadays, slope movements of such dimensions could have catastrophic consequences on inhabited islands. Additionally, in several cases there has been proved emergence of tsunami waves with far-reaching impacts because of these movements. Tsunami hazards have been one of the impulses to examine the probability of these slope movements' developments in today's conditions. In this work, the author tries to prove the impact of seismic activity and rapid changes of ocean water level on the slope stability model of San Andrés giant landslide on the El Hierro Island, Canary Islands archipelago. The geotechnical model parameters were obtained from laboratory analysis of rock material from the island. Then, slope stability models on San Andrés giant landslide were prepared using different combinations of input...
Giant landslides on volcanic islands on the example of the Hawaii archipelago
Kalina, Jan ; Blahůt, Jan (advisor) ; Novotný, Jan (referee)
The bachelor thesis deals with the largest slope movements on Earth - landslides on volcanic islands, with focus on the Hawaii archipelago. It summarizes the knowledge of their classification and evaluates their possible causes with respect to the specifics of the volcanic islands. After introduction, it focuses on a specific area of interest that is the Hawaiian Islands and describes landslides that have occurred during the geological history of these islands. A database of all known the 19 largest landslides is also made, where their location, classification, age and morphometric data such as volume, perimeter, area, length, width and height are recorded. This database will become a part of the database of the giant landslides on volcanic islands on Earth, which is being created at the Institute of Rock Structure and Mechanics of the Czech Academy of Sciences. The database is further explored in the statistical chapter, where the mathematical procedure for calculating the relative runout of the slope movement and the potential energy of the landslide is explained. Additionally, the box plots comparing the selected morphometric parameters are created. For illustrative nature, a map of the giant landslides is also included.
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...
Slope movement analysis in the northwestern part of the Příhrazská plošina platform and evaluation of sandstone properties relative to the stability situation
Vorlíček, Petr ; Blahůt, Jan (advisor) ; Vařilová, Zuzana (referee)
The Northwestern part of the Příhrazská platform is known for its processes, the first scientifically studied movement occurred here in 1926 and had catastrophic consequences. This work deals with the evaluation of the selected continuous slope movements in the north- western part of Příhrazská platform and builds on previous measurements. The measured movements are compared with meteorological data, with the surrounding hydrogeological borehole data, and compared with other monitoring site in the vicinity. In the second part, the work focuses on clarifying the problem of the increased susceptibility of the monitored rock tower for weathering and comparison of the properties of sandstone material from this tower with surrounding sandstones from the vicinity and other localities. Attention is especially paid to the influence of the biological crusts, whose significant influence is confirmed. For the investigation field and laboratory methods were used in combination with the use of computer programs.
Analysis of slope deformation from the Mužský hill, Příhrazská plošina plateau
Pantůčková, Klára ; Blahůt, Jan (advisor) ; Lešner, Jeroným (referee)
This thesis is dealing with analysis of landslide on the eastern hillside of the Mužský hill, which lies on the Příhrazská plošina Plateau in Český ráj. Příhrazská plošina Plateau belongs to areas, where landslides occur very often and it is well known for a destructive landslide at Dneboh village in 1926. Landslide under the Mužský hill originated on hillside of a Tertiary volcano, which penetrated Cretaceous sandstones and claystones. That distinguishes it from other landslides in the area. Geophysical method of electrical resistivity tomography was used for finding landslides slip surface. Due to small resistivity contrast between landslide mass and underlying claystones, it was not able to identify slip surface with high certainty. The results show only some indications of it. The geophysical exploration however, proved that the landslide mass is overlaying originally exposed sandstone blocks in the accumulation part of the landslide. The whole area of the landslide was mapped into engineering geology map of slope stability at 1:2000 scale with the help of GPS. Slope map on the basis of digital model terrain acquired from LiDAR measurements was used, as a basis of new map. This slope map provided more information about older landslides around examined landslide. From results of the mapping was...

National Repository of Grey Literature : 15 records found   1 - 10next  jump to record:
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5 Blahut, Jan
2 Blahút, Jozef
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