Ano (87)
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Optimization methods for inverse problems with energy norm
Hrtus, Rostislav; Haslinger, Jaroslav; Blaheta, Radim
2014 - anglický
The paper deals with the application of the energy norm in the inverse problem which is based on a minimization of a nonlinear least squares function. Three different parameter distribution examples are solved by the steepest descent, nonlinear conjugate gradient and Newton methods. Efficiency comparison is also presented.
Klíčová slova:
optimization methods; parameter distribution; Newton methods
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Optimization methods for inverse problems with energy norm
The paper deals with the application of the energy norm in the inverse problem which is based on a minimization of a nonlinear least squares function. Three different parameter distribution examples ...
Slightly generalized regular space decompositions
Kolcun, Alexej
2014 - anglický
Space decomposition methods represent an important part of numerical modelling process. In many applications it is suitable to use the simplest case of decomposition { regular rectangular grid: the whole raster graphic concept can be seen from this point of view. Dierent raster concept, based on regular hexagonal mesh, is analyzed e.g. in [18]. Generalized task { decomposition of the space to the set of the identical elements have been presented in various research areas since a long time, and it is connected with Hilbert's 18th problem [9], [10].
Klíčová slova:
space decomposition methods; numerical modelling; discretization
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Slightly generalized regular space decompositions
Space decomposition methods represent an important part of numerical modelling process. In many applications it is suitable to use the simplest case of decomposition { regular rectangular grid: the ...
Geo-oriented mathematical modelling: multiphysics and multiscale
Blaheta, Radim
2014 - anglický
This contribution is aimed at a brief introduction to two important aspects of nowadays geo-oriented mathematical modelling: multiphysics and multiscale. Moreover, these types of modelling are illustrated on problems currently solved at the Institute of Geonics AS CR.The multiphysics means modelling of coupled physical phenomena. In the case of the geotechnical engineering, it is typically modelling of coupled thermo-hydro-mechanical (THM) processes, in other engineering branches, we can consider similar models, e.g. coupling of electric and mechanical phenomena. The modelling of coupled processes is particularly involved in modelling of sealing and plugging effects of bentonite barriers used in the design of underground repository of spent nuclear fuel. At present, the team at the Institute of Geonics is involved in the solution of Task A of the Decovalex 2015 project aimed at modelling in-situ SEALEX experiments, which were performed in Tournemire underground laboratory in France.
Klíčová slova:
cyclic loading; thermal loading; dynamic loading; creep; underground opening; cyklické zatěžování; tečení
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Geo-oriented mathematical modelling: multiphysics and multiscale
This contribution is aimed at a brief introduction to two important aspects of nowadays geo-oriented mathematical modelling: multiphysics and multiscale. Moreover, these types of modelling are ...
The history of measurement of rock mechanical properties at the Institute of Geonics AS CR
Konečný, Pavel; Blaheta, Radim
2014 - anglický
The rock testing and evaluation of parameters for description of rock behaviour is an important part of the research at the Institute of Geonics AS CR since its foundation as an independent institute of the Czechoslovak Academy of Sciences in 1982. Focusing on mechanical testing, the first testing device, the hydraulic press EDZ 100H made in GDR with maximum force 1000 kN, was acquired in 1980, when only a branch of the Mining Institute existed in Ostrava. This equipment was substantially extended in the eighties by two „small“ mechanical presses FPZ 100 (max. force 100kN) and FPZ 10 (max. force 10kN) purchased in 1987 from GDR. But a really great progress came with the mechanical press ZWICK 1494 (500 kN) controlled by computer with a possibility of recording and processing the data. This press was bought from ZWICK Ulm (FRG) in 1985. The deformation measurement was realized by the dial test indicators. The described equipment was used for rock testing with focus on elastic behaviour and uniaxial strength limits, which were required for solving engineering problems mostly related to the coal mining.
Klíčová slova:
rock testing; measurement under uniaxial and triaxial loading; permeability tests; zkoušení; mechanické lisy
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
The history of measurement of rock mechanical properties at the Institute of Geonics AS CR
The rock testing and evaluation of parameters for description of rock behaviour is an important part of the research at the Institute of Geonics AS CR since its foundation as an independent institute ...
High performance computing in micromechanics
Blaheta, Radim; Hrtus, Rostislav; Jakl, Ondřej; Starý, Jiří
2014 - anglický
By micromechanics we understand analysis of the macroscale response of materials through investigation of processes in their microstructure. Here by the macroscale, we mean the scale of applications, where we solve engineering problems involving materials like different metals and composites in aircraft design or rocks and concrete in a dam construction. Different applications are characterized by different characteristic size. At macroscale the materials mostly look as homogeneous or they are idealized as homogeneous or piecewise homogeneous. A substantial heterogeneity is hidden and appears only after more detailed zooming view into the material.
Klíčová slova:
analysis on CT scans; high resolution finite element solution; boundary value problems; solution of inverse problems
Plné texty jsou dostupné v digitálním repozitáři NUŠL
High performance computing in micromechanics
By micromechanics we understand analysis of the macroscale response of materials through investigation of processes in their microstructure. Here by the macroscale, we mean the scale of ...
Inner Structure of Functionala Region: Theoretical Aspects
Erlebach, M.; Klapka, Pavel; Halás, M.; Tonev, P.
2014 - anglický
The contribution addresses theoretically the inner structure of functional region. It defines types of functional regions on the basis of selected criteria regarding their inner structure. As classification criteria a number of cores in a region, their hierarchical importance and ch aracter of interaction relationships between them and within a region have been employed. A study of functional regions is not important only for geography, but also for regional and spatial science and for planning practise.
Klíčová slova:
functional region; inner structure; types of regions
Dokument je dostupný na externích webových stránkách.
Inner Structure of Functionala Region: Theoretical Aspects
The contribution addresses theoretically the inner structure of functional region. It defines types of functional regions on the basis of selected criteria regarding their inner structure. As ...
Texture of cokes in relation to parameters of coal and coke
Pěgřimočová, J.; Kožušníková, Alena
2013 - anglický
The article presents a proposal of the simplified classification of textures of coke and the relationship between the texture parameters of coke both coal, from which the coke was made, and properties of the coke.
Klíčová slova:
texture of cokes; coal; phase carbon forms
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Texture of cokes in relation to parameters of coal and coke
The article presents a proposal of the simplified classification of textures of coke and the relationship between the texture parameters of coke both coal, from which the coke was made, and ...
Pulsed liquid jet generated by pulse multiplication technique
Dvorský, R.; Sitek, Libor; Sochor, T.
2013 - anglický
First theoretical papers summarizing the high mechanical energy cumulation when high-speed drops impacting the solid surface as a result of the water hammer effect have been known since 1960’s. Heymann has demonstrated that pressure maximum in the impact of a spherical drop of a liquid is several times higher than the presupposed maximum for the classical water hammer effect. The latter maximum pressure itself exceeds the mere stagnation pressure of the continuous jet many times hereat. When developing devices for pulse jet generation a new generalization of the classical water hammer theory for high pressures has been implemented. Based on this the new patented principle of “pulse multiplication” has been formulated. The pulse multiplier is the source of high-pressure pulses with 100% depth of modulation of liquid jet discharge velocity that allows increasing the jet disintegration effect significantly without the abrasive material application.
Klíčová slova:
pulse liquid jet; water hammer effect; pulse intensifier; high-pressure pulses
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Pulsed liquid jet generated by pulse multiplication technique
First theoretical papers summarizing the high mechanical energy cumulation when high-speed drops impacting the solid surface as a result of the water hammer effect have been known since 1960’s. ...
Preliminary analysis of volume material removal at bone cement disintegration by pulsating water jet
Lehocká, D.; Hloch, S.; Foldyna, Josef; Monka, P.; Monková, K.; Brezíková, K.
2013 - anglický
The article deals with preliminary analysis of material removal during disintegration of bone cement. This article was created to show possibilities of pulsating water jet utilization in medicine. Experiments with pulsating water jet were done using two types of nozzles - flat and round. Traces in bone cement were measured by optical profilemeter MicroProf FRT. Results show that pulsating water jet will be possible focuses as a tool for medical purposes, but further detailed research is needed.
Klíčová slova:
pulsating water jet; PMMA - bone cement; volume removal
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Preliminary analysis of volume material removal at bone cement disintegration by pulsating water jet
The article deals with preliminary analysis of material removal during disintegration of bone cement. This article was created to show possibilities of pulsating water jet utilization in medicine. ...
Research on effects of pulsating water jets on concrete
Sitek, Libor; Bodnárová, L.
2013 - anglický
An article briefly presents results achieved during laboratory and in-situ tests of removing surface layers of concrete exposed to various environments using several types of high-velocity water jets commonly used in the rehabilitation praxis or advanced water jets the use of which is expected in the near future. The effects of pulsating jets were always compared with classical continuous jets under identical or similar working conditions.
Klíčová slova:
degraded concrete; structure rehabilitation; concrete surface; pulsating water jet
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Research on effects of pulsating water jets on concrete
An article briefly presents results achieved during laboratory and in-situ tests of removing surface layers of concrete exposed to various environments using several types of high-velocity water jets ...
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