|
|
Selected Extensions of the Albegraic System Octave
Salač, Radek ; Smrčka, Aleš (referee) ; Vojnar, Tomáš (advisor)
This work deals with issues linked to solving system of linear equations in the environment of numerical computer. It describes the fundamental algorithms emphasizing their positive as well as negative sides. The work is devoted to general issues such as time complexity and memory demandingness of given algorithms. In the last part, the process of implementation of selected procedures into the algebraic system Octave is described.
|
|
|
Optimation of inoculation process of ductile iron
Ulm, Daniel ; Pecina, Vladimír (referee) ; Roučka, Jaromír (advisor)
The master‘s thesis deals in theoretical part with the casting classification, ductile iron casting, its inoculation and modification and quality evaluation using thermal analysis, image analysis and testing of mechanical properties. The aim of the practical part was to test the effects of preconditioning on the properties of ductile iron and to find out whether it is able to replace the current method of inoculation or to increase the mechanical properties of ductile iron castings. The state of the ductile iron was under control by spectral and thermal analysis. The mechanical properties and image analysis were checked on finished casting.
|
|
|
Effect of morphine on the resistance of the heart to ischemia
Mošovská, Linda ; Neckář, Jan (advisor) ; Žurmanová, Jitka (referee)
2. Abstract Opioids are considered as dangerous and addictive substances, mainly due to synthetic opioids such as heroin. It was discovered, that these substances can play an important role in myocardial ischemia because they can limit the damage of the heart tissue that occurs during a heart attack. Since that heart attack is the most common cardiovascular disease, the protective effect is significant. Cardioprotective effect is mainly mediated through δ opioid receptors, but the few studies have shown cardioprotective effect mediated through κ opioid receptors. The protective effect occurs by activation of opioid receptors by their agonists (eg. morphine or TAN-67), either before ischemia (opioid preconditioning) or before reperfusion (opioid postconditioning). The signaling pathway of cardioprotection include mitochondrial KATP channel, Gi/o proteins, protein kinase C, tyrosine kinases and reactive oxygen species.
|
|
|
Cardiac ischemic tolerance of hypertensive rats
Jelínek, Jan ; Neckář, Jan (advisor) ; Sotáková, Dita (referee)
The aim of this thesis is to summarize current knowledge about the influence of the ischemic- reperfusion injury at the myocard of hypertensive subjects. First part of this thesis is focused on the description of ischemia, reperfusion and changes in the myocardial metabolism during these processes. These changes in the myocardial metabolism are for example necrosis or apoptosis of the myocardial cells. The second part describes the currently known cardioprotective phenomena. This part also compares their effects. The signalization of preconditioning, the second window of preconditioning and the postconditioning are described here in more details. Third part is focused on the description of the risk factors connected to the ICHS and hypertension. It describes also classes of hypertension, clinical and experimental methods of hypertension treatment, description of the laboratory breeds of hypertensive rats. In the last part of this thesis I describe the influence of hypertension on the I-R injury in current laboratory studies. In the most studies spontaneously hypertensive rats (SHR) were used. As a normotensive controls Wistar-Kyoto rats were mostly used. For some other experiments transgenic genetic rats (TGR) were used. Powered by TCPDF (www.tcpdf.org)
|
|
|
Numerical methods for vortex dynamics
Outrata, Ondřej ; Hron, Jaroslav (advisor) ; Šístek, Jakub (referee)
Two aspects of solving the incompressible Navier-Stokes equations are described in the thesis. The preconditioning of the algebraic systems arising from the Finite Element Method discretization of the Navier-Stokes equations is complex due to the saddle point structure of the resulting algebraic problems. The Pressure Convection Diffusion Reaction and the Least Squares Commutator preconditioners constitute two possible choices studied in the thesis. Solving the flow problems in time-dependent domains requires special numerical methods, such as the Fictitious Boundary method and the Arbitrary Lagrangian Eulerian formulation of Navier-Stokes equations which are used in the thesis. The problems examined in the thesis are simulations of experiments conducted in liquid Helium at low temperatures. These simulations can be used to establish a relationship between vorticity and new quantity pseudovorticity in an experiment-like setting.
|
|
|
Krylov Subspace Methods - Analysis and Application
Gergelits, Tomáš ; Strakoš, Zdeněk (advisor) ; Farrell, Patrick (referee) ; Herzog, Roland (referee)
Title: Krylov Subspace Methods - Analysis and Application Author: Tomáš Gergelits Department: Department of Numerical Mathematics Supervisor: prof. Ing. Zdeněk Strakoš, DrSc., Department of Numerical Mathematics Abstract: Convergence behavior of Krylov subspace methods is often studied for linear algebraic systems with symmetric positive definite matrices in terms of the condition number of the system matrix. As recalled in the first part of this thesis, their actual convergence behavior (that can be in practice also substantially affected by rounding errors) is however determined by the whole spectrum of the system matrix, and by the projections of the initial residual to the associated invariant subspaces. The core part of this thesis investigates the spectra of infinite dimensional operators −∇ · (k(x)∇) and −∇ · (K(x)∇), where k(x) is a scalar coefficient function and K(x) is a symmetric tensor function, preconditioned by the Laplace operator. Subsequently, the focus is on the eigenvalues of the matrices that arise from the discretization using conforming finite elements. Assuming continuity of K(x), it is proved that the spectrum of the preconditi- oned infinite dimensional operator is equal to the convex hull of the ranges of the diagonal function entries of Λ(x) from the spectral decomposition K(x) =...
|
|
|
Incomplete Cholesky factorization
Hoang, Phuong Thao ; Tůma, Miroslav (advisor) ; Tichý, Petr (referee)
The thesis is about the incomplete Cholesky factorization and its va- riants, which are important for preconditioning a system with symmetric and positive definite matrix. Our main focus is on solving these systems, which arise in many technical applications and natural sciences, using preconditioned Con- jugate Gradients. Besides many other ways we can apply Cholesky factorization approximately, incompletely. In this thesis we study existence of the incomplete Cholesky factorization and we evaluate behaviour and potential of different vari- ants of the generic algorithm. 1
|
|
|
Towards efficient numerical computation of flows of non-Newtonian fluids
Blechta, Jan ; Málek, Josef (advisor) ; Herzog, Roland (referee) ; Süli, Endré (referee)
In the first part of this thesis we are concerned with the constitutive the- ory for incompressible fluids characterized by a continuous monotone rela- tion between the velocity gradient and the Cauchy stress. We, in particular, investigate a class of activated fluids that behave as the Euler fluid prior activation, and as the Navier-Stokes or power-law fluid once the activation takes place. We develop a large-data existence analysis for both steady and unsteady three-dimensional flows of such fluids subject either to the no-slip boundary condition or to a range of slip-type boundary conditions, including free-slip, Navier's slip, and stick-slip. In the second part we show that the W−1,q norm is localizable provided that the functional in question vanishes on locally supported functions which constitute a partition of unity. This represents a key tool for establishing local a posteriori efficiency for partial differential equations in divergence form with residuals in W−1,q . In the third part we provide a novel analysis for the pressure convection- diffusion (PCD) preconditioner. We first develop a theory for the precon- ditioner considered as an operator in infinite-dimensional spaces. We then provide a methodology for constructing discrete PCD operators for a broad class of pressure discretizations. The...
|
|
|
The role of mitochondria in cardioprotective effect induced by hypoxia in rat
Lomnický, Matouš ; Žurmanová, Jitka (advisor) ; Hlaváčková, Markéta (referee)
Aerobic organisms need sufficient oxygen supply to maintain homeostasis. These organisms are frequently exposed in hypoxic environments naturally, and also occur in hypoxic states in various pathological conditions. Cardioprotective effect of hypoxia had been recognised more than 30 years ago; and later on, cardioprotective effects of ischemic preconditioning were discovered. Long term exposure to hypobaric hypoxia activates cardioprotective mechanisms, which lower the aftermathes of short term ischemia of myocardia and the effects of further health complications. The core of protective mechanisms has not yet been fully clarified. This work deals with the significance of mitochondria on cardioprotection during hypobaric hypoxia adaptation. This work describes physiological adaptive processes on selected animals on natural hypoxic conditions and also molecular mechanisms, examined on experimental models. Molecular mechanisms of the origins of cardioprotective effects discovered so far, mainly indicate PKC signal pathways through thyrosine kinase and mitogenes of activated kinase and also indicate an activation of sarcKATP-channels and mitoKATP-channels. Opening of these channels can protect mitochondria against a Ca2+ overload, or can lead to an increase in mitochondrial capacity which is possibly connected...
|
|
|
Krylov Subspace Methods - Analysis and Application
Gergelits, Tomáš ; Strakoš, Zdeněk (advisor) ; Farrell, Patrick (referee) ; Herzog, Roland (referee)
Title: Krylov Subspace Methods - Analysis and Application Author: Tomáš Gergelits Department: Department of Numerical Mathematics Supervisor: prof. Ing. Zdeněk Strakoš, DrSc., Department of Numerical Mathematics Abstract: Convergence behavior of Krylov subspace methods is often studied for linear algebraic systems with symmetric positive definite matrices in terms of the condition number of the system matrix. As recalled in the first part of this thesis, their actual convergence behavior (that can be in practice also substantially affected by rounding errors) is however determined by the whole spectrum of the system matrix, and by the projections of the initial residual to the associated invariant subspaces. The core part of this thesis investigates the spectra of infinite dimensional operators −∇ · (k(x)∇) and −∇ · (K(x)∇), where k(x) is a scalar coefficient function and K(x) is a symmetric tensor function, preconditioned by the Laplace operator. Subsequently, the focus is on the eigenvalues of the matrices that arise from the discretization using conforming finite elements. Assuming continuity of K(x), it is proved that the spectrum of the preconditi- oned infinite dimensional operator is equal to the convex hull of the ranges of the diagonal function entries of Λ(x) from the spectral decomposition K(x) =...
|
guest ::
