No (257)
Yes (87)
Number of found documents:
344
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Community area risk assessment for flash flood
Kolejka, Jaromír; Rapant, P.; Krejčí, Tomáš
2017 - English
The flash floods forecasting is struggling mainly with extraordinary irregularities in origin of causal precipitations. They only in conjunction with the territory water saturation caused by antecedent precipitations start effect of other local factors that can consequences of short-term extreme precipitation either worsen or mitigate vice versa. Other community area features represent a permanent potential for an adequate territory response after heavy rains. According to current knowledge, it is possible to assess the flash floods hazard of a particular territory in case of extreme precipitation in advance. If such precipitations are already on the ground, or if they are just coming up in the atmosphere, the local flood control headquarters has at least time enough to call alarm and issue a flood warning. In the ideal case, it is possible to incorporate such area assessment into the concept of decision-making of the disaster staff and to insert it into the master plan documentation. The aim of this text is to present above mentioned original method, which can be used in authomatic GIS environment by public administration as well as other users. Suggested procedure is based on automatic hydrologic modelling in ArcGIS platform in combination with advanced digital terrain model. Delimitation of partial catchment basins is also part of our proces, which enables to decide about the risk value of the area in more detail using weighted arithmetic mean. These methods result to detailed imagination about probably threatened localities - and it is essential tool for local authorities and their decision making process in case of early warning.
Keywords:
flash flood; local development; risk assessment; planning documentation
Available at various institutes of the ASCR
Community area risk assessment for flash flood
The flash floods forecasting is struggling mainly with extraordinary irregularities in origin of causal precipitations. They only in conjunction with the territory water saturation caused by ...
Bifurcations in contact problems with Coulomb friction
Ligurský, Tomáš; Renard, Y.
2017 - English
To explore the bifurcation in this contact problem, we have taken uniform meshes with 4096, 16384, 65536 and 262144 triangles. We shall show that the bifurcation behaviour is more complex here. Branches 1 and 4 approach one another for finer meshes, and they disappear both for the finest mesh. Nevertheless, regarding the branching of the corresponding contact problem with forces h = (h1,h2) over the plane h1-h2, one can find it stable and convergent, again. \n
Keywords:
bifurcation; contact problem; Coulomb friction
Fulltext is available at external website.
Bifurcations in contact problems with Coulomb friction
To explore the bifurcation in this contact problem, we have taken uniform meshes with 4096, 16384, 65536 and 262144 triangles. We shall show that the bifurcation behaviour is more complex here. ...
Large-scale geosimulations using GEM and trilions
Blaheta, Radim; Jakl, Ondřej; Hrtus, Rostislav; Kolcun, Alexej; Kohut, Roman; Starý, Jiří; Turan, E.
2017 - English
The project deals with efficient solution of singular symmetric positive semidefinite problems. Our motivation arises from the \nneed to solve special problems of geotechnics, e.g. to perform upscaling analysis of geocomposites. In that and other applications we have to solve boundary problems with pure Neumann boundary conditions. We show that the stabilised PCG method with various preconditioners is a good choice for systems resulting from the numerical solution of Neumann problems, or more generally problems with a known small dimensional null space. The work was also taken as an opportunity to compare parallel implementations of the orresponding solvers, namely implementations in the in-house finite element software GEM and implementations employing components of the general Trilinos library. The studies show that the solvers based on GEM are highly competitive with its recognised counterpart.
Keywords:
singular symmetric positive semidefinite problems; special problems of geotechnics; PCG method
Fulltext is available at external website.
Large-scale geosimulations using GEM and trilions
The project deals with efficient solution of singular symmetric positive semidefinite problems. Our motivation arises from the \nneed to solve special problems of geotechnics, e.g. to ...
Perception of wind power plants construction on the local level: Case studies in East Bohemia
Janová, M.; Kunc, J.; Frantál, Bohumil
2017 - English
The paper aims to evaluate selected findings of a research regarding the attitudes of the inhabitants of East Bohemian municipalities (Anenska Studanka and Vitezna) towards the construction of wind power plants and the perception thereof. A survey was carried out among the inhabitants of the two municipalities, as well as nearby municipalities and guided interviews were conducted with their mayors. The two selected sites differ in population numbers, time of power plant construction, number and size of the turbines and form of financial settlement. In the case of Vitezna, the power plant in question was community-funded, meaning that a portion of the shares was offered to the inhabitants (a unique case in the Czech Republic). The results indicated that, over time, the attitudes and opinions of the respondents from all the municipalities concerned have shifted towards a more positive perception of wind power plants. They have, however, also become more polarized. Citizens' movements against further construction have been created, even though it is currently not possible in the Czech Republic, especially given that the government has cancelled funding for the support of clean power. Respondents who were found to have the fewest issues with the wind power plants were younger than 30 years, graduates of secondary education and resided at a greater distance from the stations without having direct visual contact with them from their home.
Keywords:
wind power plants; perception; local level; Eastern Bohemia
Available at various institutes of the ASCR
Perception of wind power plants construction on the local level: Case studies in East Bohemia
The paper aims to evaluate selected findings of a research regarding the attitudes of the inhabitants of East Bohemian municipalities (Anenska Studanka and Vitezna) towards the construction of wind ...
SNA´17 - Seminar on Numerical Analysis
Blaheta, Radim; Starý, Jiří; Sysalová, Dagmar
2017 - English
Seminar on Numerical Analysis 2017 (SNA'17) is a continuation in a series of SNA events held in different places in the Czech Republic and organized alternatively by Ostrava and Prague institutions. TheSNA'17isorganizedbytheInstituteofGeonicsoftheCASincollaborationwith VŠB - Technical University of Ostrava and IT4Innovations National Supercomputing Centre. Conference location is one of the lecture rooms in New Aula of the VŠB-TU Ostrava. Let us note that SNA 2016 was reshaped to EMS School in Applied Mathematics (ESSAM) devoted to mathematical modelling, numerical analysis and scientific computing. The SNA'17 is turning back to more traditional winter event. It provides opportunity for meeting and mutual information of the community working in computational mathematics and computer science, but an important part of SNA is devoted to the Winter School with tutorial lectures focused on selected important topics within the scope of numerical methods and modelling.
Keywords:
mathematics; numerical analysis; modelling
Fulltext is available at external website.
SNA´17 - Seminar on Numerical Analysis
Seminar on Numerical Analysis 2017 (SNA'17) is a continuation in a series of SNA events held in different places in the Czech Republic and organized alternatively by Ostrava and Prague institutions. ...
The Flow of Mixture Vapors in the Vacuum Column K101, Nominal and Reduced Capacity
Říha, Zdeněk
2017 - English
The report contains CFD results and description of the gas mixture flow in the bottom part of the vacuum column K101. There were solved two cases. Both cases had the same geometry. The difference between ones was in quantity of vapors on the inputs. The first case was calculated for the nominal quantity of vapors. The second case was calculated for reduced quantity (60% of nominal quantity) of vapors. Calculated results of above mentioned cases are placed in report´s enclosures 1 and 2.
Keywords:
CFD results; vacuum column; gas mixture flow
Available at various institutes of the ASCR
The Flow of Mixture Vapors in the Vacuum Column K101, Nominal and Reduced Capacity
The report contains CFD results and description of the gas mixture flow in the bottom part of the vacuum column K101. There were solved two cases. Both cases had the same geometry. The difference ...
Application of high speed water jet technology for concrete repair
Bodnárová, L.; Sitek, Libor; Foldyna, Josef; Jarolím, T.
2017 - English
This article brings selected knowledge from the long-term cooperation between\nthe Brno University of Technology, the Faculty of Civil Engineering, the Institute of\nTechnology of Building Materials and Components, and the Academy of Sciences of\nthe Czech Republic, v.v.i., Institute of Geonics, Ostrava – Poruba in the field of\nthe interaction of high-speed water jets and concrete, especially with regard to\nthe use of high-speed water jet technology for the removal of surface layers of\nconcrete during repair of concrete.
Keywords:
high speed water jet (HSWJ); concrete; concrete repair; X-ray CT; carbon nanotubes (CNTs)
Available on request at various institutes of the ASCR
Application of high speed water jet technology for concrete repair
This article brings selected knowledge from the long-term cooperation between\nthe Brno University of Technology, the Faculty of Civil Engineering, the Institute of\nTechnology of Building Materials ...
Evaluation of selected surface characteristics of CW004A copper disintegrated by PWJ
Lehocká, D.; Klich, Jiří
2017 - English
Paper deals with copper CW004A surface characteristics evaluation after\ndisintegration by enhanced pulsating water jet. The main aim was identify and\ndescribe areas of pulsating water jet disintegration effects on material with using\ncircular nozzle diameter. 25 samples were disintegrated at change traverse speed\nv = 0.1 – 20 mm·s-1, for assessment of individual areas formation. Surface\ncharacteristics were evaluated based on surface roughness parameters Ra [μm],\nRz [μm], Rp [μm], Rv [μm], mass material removal Δm [mg.mm-1] and volume\nmaterial removal Vm [mm3]. Based on experimental investigation, three areas of\npulsating water jet effects on material were determined.
Keywords:
pulsating water jet; copper; roughness; topography
Available on request at various institutes of the ASCR
Evaluation of selected surface characteristics of CW004A copper disintegrated by PWJ
Paper deals with copper CW004A surface characteristics evaluation after\ndisintegration by enhanced pulsating water jet. The main aim was identify and\ndescribe areas of pulsating water jet ...
Flow Field Analysis in Abrasive Head as Tool for High-Speed Abrasive Jet Cutting
Říha, Zdeněk; Zeleňák, Michal
2017 - English
The article presents an analysis of the calculated flow field of water, vapor and\nabrasive particles in the inner geometry of a tool called the abrasive head using\na multiphase numerical flow model. The results of the above-mentioned analysis\nare compared with measured values of abrasive particle velocities at the outlet of\nthe abrasive head. For measuring of abrasive particle velocities, the PIV method\nwas used.
Keywords:
abrasive head; high-speed water jet; abrasive particle velocity
Available on request at various institutes of the ASCR
Flow Field Analysis in Abrasive Head as Tool for High-Speed Abrasive Jet Cutting
The article presents an analysis of the calculated flow field of water, vapor and\nabrasive particles in the inner geometry of a tool called the abrasive head using\na multiphase numerical flow model. ...
Professor Ivo Marek (1933-2017)
Blaheta, Radim; Tůma, Miroslav
2017 - English
Ivo Marek, Professor at Charles University and the Czech Tec\nhnical University in Prague, was for many decades one of the best-known Czech ma\nthematicians, who contributed significantly to the development of computa\ntional methods and numerical analysis. At the same time, he was a teacher and a le\nading personality that integrated and influenced the Czech mathematical commu\nnity.
Fulltext is available at external website.
Professor Ivo Marek (1933-2017)
Ivo Marek, Professor at Charles University and the Czech Tec\nhnical University in Prague, was for many decades one of the best-known Czech ma\nthematicians, who contributed significantly to the ...
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