No (257)
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257
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A Comparison of Preconditioning Methods for Saddle Point Problems with an Application to Porous Media Flow Problems
Axelsson, Owe; Blaheta, Radim; Hasal, Martin
2016 - English
The paper overviews and compares some block preconditioners for the solution of saddle point systems, especially systems arising from the Brinkman model of porous media flow. The considered preconditioners involve different Schur complements as inverse free Schur complement in HSS (Hermitian - Skew Hermitian Splitting preconditioner), Schur complement to the velocity matrix and finally Schur complement to a regularization block in the augmented matrix preconditioner. The inverses appearing in most of the considered Schur complements are approximated by simple sparse approximation techniques as element-by-element and Frobenius norm minimization approaches. A special interest is devoted to problems involving various Darcy, Stokes and Brinkman flow regions, the efficiency of preconditioners in this case is demonstrated by some numerical experiments.
Keywords:
schur complements; linear-systems; high performance computing
Available at various institutes of the ASCR
A Comparison of Preconditioning Methods for Saddle Point Problems with an Application to Porous Media Flow Problems
The paper overviews and compares some block preconditioners for the solution of saddle point systems, especially systems arising from the Brinkman model of porous media flow. The considered ...
Composition and microstructure of plasters in convent of the Želiv Monastery (Czech Republic)
Rezek, P.; Martinec, Petr; Ščučka, Jiří; Majstríková, T.
2016 - English
The paper deals with analyses of composition and structure of historic plasters from the convent building of the Želiv Monastery (Czech Republic). Composition and microstructure of plaster samples taken from the historic object have been assessed using both traditional and advanced analytical methods. The following techniques have been used for the assessment of binders and fine aggregates in plasters: optical microscopy of thin sections, mineralogical and petrographic analysis of separated components, infrared spectroscopy, and thermal analysis. Presented results show significant differences in character of the studied materials of varying age and demonstrate the effectiveness of the taken analytical approach.
Keywords:
aggregate; thermal analysis; historic plaster; infrared spectroscopy; optical microscopy
Available at various institutes of the ASCR
Composition and microstructure of plasters in convent of the Želiv Monastery (Czech Republic)
The paper deals with analyses of composition and structure of historic plasters from the convent building of the Želiv Monastery (Czech Republic). Composition and microstructure of plaster samples ...
Stress state rock mass monitoring ahead of longwall No. 371 202 at 2ndA block, Mine Plant 2, OKD, a.s
Waclawik, Petr; Ptáček, Jiří; Koníček, Petr; Vavro, Martin; Staš, Lubomír; Souček, Kamil; Kukutsch, Radovan; Kajzar, Vlastimil
2015 - English
Generally, the accurate knowledge of the stress strain state of the rock mass in the neighbourhood of the mining galleries and underground openings is absolutely critical for their precise support designing, not only in the vicinity of them, but also at a greater distance from them if the phenomenon affecting the rock mass stress fields occurs. Measurement (investigation) of the rock stress is usually carried out by interpretation of the rock mass deformation processes, which can be relatively precisely observed and measured. The roadways are loaded not only by rock pressures in the front of the coalfaces but also by destress blasting realised in the overburden rock seam in the scope of the rockburst prevention. In addition, the rock stress distribution is influenced by old mining activities too, for example by abandoned coal pillars in the seams in overburden, respectively by goaf in the excavated seam. All of these factors can significantly affect the stress-strain behaviour of the rock mass around the mining works.
Keywords:
stress state; monitoring; rock mass
Available at various institutes of the ASCR
Stress state rock mass monitoring ahead of longwall No. 371 202 at 2ndA block, Mine Plant 2, OKD, a.s
Generally, the accurate knowledge of the stress strain state of the rock mass in the neighbourhood of the mining galleries and underground openings is absolutely critical for their precise support ...
CFD model of mixture gas flow in the vacuum column 12T-70102, existing state of internals
Říha, Zdeněk
2015 - English
The report contains description of fluid flow for case with existing state of the column 12T -70102. Vapor flow was mainly calculated in the above mentioned geometry. In last iteration the liquid droplet (diameter 0,3mm) were injected into the geometry through the nozzle 12, see enclosure in the report. Introductory section of the enclosuere contains pictures with geometry and boundary conditions description, See figure G1. Then, slice plan follows, see figure G2. Next pictures show distribution of pressure and velocity on given slices. Pictures at the end of the enclosure show path-lines distribution and droplets particle traces distribution in the solved geometry.
Keywords:
CFD model; vacuum column; gas flow
Available on request at various institutes of the ASCR
CFD model of mixture gas flow in the vacuum column 12T-70102, existing state of internals
The report contains description of fluid flow for case with existing state of the column 12T -70102. Vapor flow was mainly calculated in the above mentioned geometry. In last iteration the liquid ...
CDF model of mixture gas flow in the vacuum column 12T-70102, revamp tower
Říha, Zdeněk
2015 - English
The report contains description of fluid flow for case with revamp tower of the column 12T -70102. Vapor flow was mainly calculated in the above mentioned geometry. In last iteration the liquid droplet (diameter 0,3mm) were injected into the geometry through the nozzle 12, see enclosure in the report. Introductory section of the enclosuere contains pictures with geometry and boundary conditions description, See figure G1. Then, slice plan follows, see figure G2. Next pictures show distribution of pressure and velocity on given slices. Pictures at the end of the enclosure show path-lines distribution and droplets particle traces distribution in the solved geometry.
Keywords:
CDF model; vacuum column; gas flow
Available on request at various institutes of the ASCR
CDF model of mixture gas flow in the vacuum column 12T-70102, revamp tower
The report contains description of fluid flow for case with revamp tower of the column 12T -70102. Vapor flow was mainly calculated in the above mentioned geometry. In last iteration the liquid ...
Regional and flash flood as a limiting factor for development
Kolejka, Jaromír; Krejčí, Tomáš; Rapant, P.; Inspektor, T.
2015 - English
Locating and developing factors are generally well known, studied and taken into account in the accepting of the solution. In contrast, the limiting factors of development usually stands in the background. Current data sources, knowledge and modelling technologies allow greatly anticipate the extent of the flood situation. Evaluation of the risk of regional or flash floods is not discouraging information for investors, but rather to guide their activities to a safe area. Knowledge of risk locations in the Czech Republic in terms of these types of floods also help for the safety of visitors and the local population. Appropriately incorporated findings into the development plans of all dimensions support the initiatives of local and external investors. The paper illustrates the unconventional use of public available geodata in the form of an offer vital information into regional development plans.
Keywords:
flood; regional development; limiting factors; natural hazard
Available at various institutes of the ASCR
Regional and flash flood as a limiting factor for development
Locating and developing factors are generally well known, studied and taken into account in the accepting of the solution. In contrast, the limiting factors of development usually stands in the ...
CFD model of mixture gas flow in the vacuum column D-6501
Říha, Zdeněk
2015 - English
The report contains CFD results and description of the gas mixture flow in the vacuum column D-6501. Two rotationally opposite (swirl) input nozzles S1 and S2 (ID 0,835m) create main input of vapour into the vacuum column. There are two enhanced vapour horn (EVH) distributor, for given input nozzle (S1, S2) separately. Enhanced vapour horn makes redistribution of vapour leaded from above mentioned nozzles. There also is next input of vapor given by bottom striping section. The inner diameter of the column is 7,464m and solved domain has height c. 15m. Aim of the calculation is to show distribution of calculated variables (velocity, pressure, density, etc.) on given slices. Mainly, we would like to know if the distribution of velocity is sufficiently uniform at the input into the packing bed SECTION “B”.
Keywords:
CDF model; gas flow; vacuum column
Available on request at various institutes of the ASCR
CFD model of mixture gas flow in the vacuum column D-6501
The report contains CFD results and description of the gas mixture flow in the vacuum column D-6501. Two rotationally opposite (swirl) input nozzles S1 and S2 (ID 0,835m) create main input of vapour ...
CFD model of mixture gas flow in the vacuum column D-6501, adjusted EVH and tray
Říha, Zdeněk
2015 - English
The report contains CFD results and description of the gas mixture flow in the vacuum column D-6501 with adjusted internals against last calculated case, see [1]. Two rotationally opposite (swirl) input nozzles S1 and S2 (ID 0,835m) create main input of vapour into the vacuum column. There are two enhanced vapour horn (EVH) distributor, for given input nozzle (S1, S2) separately. Enhanced vapour horn makes redistribution of vapour leaded from above mentioned nozzles. There also is next input of vapor given by bottom striping section. The inner diameter of the column is 7,464m and solved domain has height c. 15m. Aim of the calculation is to show distribution of calculated variables (velocity, pressure, density, etc.) on given slices. Mainly, we would like to know if the distribution of velocity is sufficiently uniform at the input into the packing bed SECTION “B”
Keywords:
CFD model; vacuum column; gas flow
Available on request at various institutes of the ASCR
CFD model of mixture gas flow in the vacuum column D-6501, adjusted EVH and tray
The report contains CFD results and description of the gas mixture flow in the vacuum column D-6501 with adjusted internals against last calculated case, see [1]. Two rotationally opposite (swirl) ...
GEOSITE AND GEOMORPHOSITE ASSESSMENT FOR GEOTOURISM PURPOSE: A CASE STUDY FROM THE VIZOVICKA VRCHOVINA HIGHLAND, EASTERN MORAVIA
Kirchner, Karel; Kubalíková, Lucie
2014 - English
Geotourism can be understood at a broader sense as geographical tourism sustaining environment, culture, aesthetics, heritage and the well-being of residents of a place or in a more restricted sense as a form of nature tourism that specifically focuses on landscape and geology. Geological, geomorphological and pedological sites are the most important resource for the geotourism activities. It is evident that not every site can be used for geotourism purposes. To find out which site can be used, it is necessary to identify, describe and assess various sites using a suitable assessment methodology. Based on the definition and conceptsof geotourism and the assessment methods already used for geomorphosite assessment, authors propose five groups of assessment criteria. The method was used for assessing selected sites in the Vizovickavrchovina Highland (Eastern Moravia, Outer Western Carpathians). Thanks to the assessment of the sites in this region, some potential geotourism resources were identified. Although the proposed method is numerical which should reduce the subjectivity, there is always a degree of subjectivity due to the fact that the real value of some criteria cannot be measured and it depends on assessor's experience, knowledge and preferences.
Keywords:
geodiversity; geoheritage; numerical assessment; Outer Western Carpathians
Available at various institutes of the ASCR
GEOSITE AND GEOMORPHOSITE ASSESSMENT FOR GEOTOURISM PURPOSE: A CASE STUDY FROM THE VIZOVICKA VRCHOVINA HIGHLAND, EASTERN MORAVIA
Geotourism can be understood at a broader sense as geographical tourism sustaining environment, culture, aesthetics, heritage and the well-being of residents of a place or in a more restricted sense ...
Factors of revitalization of brownfields in the Czech Republic
Osman, Robert; Frantál, Bohumil; Kunc, Josef; Klusáček, Petr; Martinát, Stanislav
2014 - English
The paper deals with reuse of brownfields in the Czech Republic. Based on the analysis of information about re-use of residual spaces are shown major changes in the current management space. The paper is based on a comparison of two data files - specifically, the existing brownfields database managed by the CzechInvest and own database of brownfields that have already been revitalized. The paper is divided into three parts, the first part of the paper analyzes the structure of a revitalized brownfields, in the second part of the paper, the structure of this file is compared with the structure of existing brownfields and the third part analyzes the factors revitalization of brownfields. The paper aims to answer the question what functions take the brownfields after revitalization and what factors determine their reuse.
Keywords:
space management; revitalization; brownfield
Available at various institutes of the ASCR
Factors of revitalization of brownfields in the Czech Republic
The paper deals with reuse of brownfields in the Czech Republic. Based on the analysis of information about re-use of residual spaces are shown major changes in the current management space. The paper ...
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