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Development and implementation of 3D geometry extraction method for topological optimization
Šotola, M. ; Rybanský, D. ; Maršálek, P. ; Halama, R. ; Kopačka, Ján ; Ježek, Ondřej ; Gabriel, Dušan ; Tejc, J. ; Pašek, M. ; Kovář, L.
This research report TN01000024/08-V012 is an output of the subtask of the project TN1000024/08 Automation and production system optimization, one of the objectives of which is to develop methods of post-processing of topological optimization (TO) results in cooperation with MECAS ESI Ltd. Three different smoothing approaches are discussed: the Taubin method, volume representation using radial basis functions and smoothing by remeshing using the Netgen library.
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Review of methods for the post-processing of topological optimization results
Kopačka, Ján ; Ježek, Ondřej ; Gabriel, Dušan ; Šotola, Martin ; Rybanský, David ; Maršálek, Pavel ; Halama, R. ; Tejc, J. ; Pašek, M. ; Kovář, L.
The research report is an output of the sub-project TN1000024/08: Automation and production system optimization in cooperation with MECAS ESI Ltd on the development of methods for post-processing of topological optimization (TO) results. In this report a detailed survey of these methods is introduced as necessary tool for seamless integration of the results TO with subsequent numerical simulations and additive manufacturing. The selected method for post-processing based on a level-set approach using radial basis functions has been implemented and successfully tested on a well-known 2D Messerschmitt-Bölkow-Blohm (MBB) beam test problem.
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A MODIFIED MATHEMATICAL MODEL OF HUMAN VENTRICULAR CARDIOMYOCYTE INCORPORATING SEPARATE T-TUBULAR AND SURFACE DYADS AND SUBMEMBRANE SPACES
Pásek, Michal ; Bébarová, M. ; Christé, G.
Intracellular Ca2+ load and Ca2+ transient are considerably dependent on distribution of sarcolemmal Ca2+ pump and Na+-Ca2+ exchanger between the t-tubular and surface membranes in the presence of separate dyadic and subsarcolemmal spaces in rat ventricular cell model. To explore analogical phenomenon in human, we modified our previously published model of human ventricular myocyte. When the t-tubular fractions of Na+-Ca2+ exchanger and of sarcolemmal Ca2+ pump were increased to the newly proposed value of 0.95 in the modified model, the following changes were observed at 1 Hz steady-state stimulation: a shortening of the action potential duration at 90% repolarisation by 6% and an increase of the cytosolic Ca2+ transient by 22%. Further analysis revealed a critical role of Ca2+ concentration changes in the subsarcolemmal spaces and consequent change in cellular Ca2+ cycling in this effect.
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Sensitivity of action potential to changes of inward rectifier potassium current IK1 is different in recent models of human ventricular cardiomyocytes
Pásek, Michal ; Šimurda, J. ; Christé, G.
The inwardly rectifying potassium current IK1 is one of the principle ionic currents responsible for repolarization phase of mammalian action potentials (APs). To estimate the impact of individual ionic currents on AP configuration, mathematical models have been widely used. In this study, we compared the effects of alcohol-induced changes of IK1 on AP duration (APD) as simulated in four recently published computer models of human ventricular cells. As expected, increasing or decreasing IK1 conductance by 20% respectively caused a shortening or a lengthening of APD. However, the effect was largely model-dependent, ranging from 1% to about 15% change of APD. Given the conflicting available experimental data on the features of IK1 in human ventricular myocytes there is a need for a set of well-established end-point constraints for a reliable human ventricular myocyte model to be generated.
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Physiological consequences of ion concentration changes in transverse-axial tubular system in a model of human ventricular cardiomyocyte
Ohlidalova, D. ; Pásek, Michal ; Šimurda, J. ; Christé, G.
A mathematical model of human ventricular cell incorporating the transverse axial tubular system (TATS) was designed and used to explore the role of TATS in human ventricular cell electrophysiological activity. The model is based on the latest quantitative description of guinea pig ventricular cell electrophysiology and modified to respect the published data obtained from human cardiac preparations. Computer simulations suggest that significant transient depletions of Ca2+ ions and accumulation of K+ ions may occur in the human TATS. The preliminary analysis of the effects of tubular Ca2+depletions on the activity of the model cell indicates their role in limitation of intracellular Ca2+ overload at higher frequencies of stimulation.
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Inženýrská mechanika
Fuis, Vladimír ; Pásek, Michal
The objective of the 14 th conference is to provide a forum for researchers to discuss the state-of-the-art in Mechanics of Solids, Fluids and Thermomechanics, this particularly in connection with problems under investigation in the Czech Republic.
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Blokáda sodíkového a přechodného draslíkového proudu perfenazinem: experimentální a simulační studie
Bébarová, M. ; Matejovič, P. ; Pásek, Michal ; Jansová, D. ; Šimurdová, M. ; Nováková, M. ; Šimurda, J.
The effect of a neuroleptic drug perphenazine on sodium current INa and transient outward potassium current Ito was studied in rat ventricular myocytes at room temperature. Perphenazine reversibly blocked INa (reducing its amplitude; IC50 = 1.24 +/- 0.10 μmol/l, nH =0.99 +/- 0.08) and Ito (accelerating its apparent inactivation with a slight decrease of its amplitude; IC50 = 38.2 +/- 3.5 μmol/l, nH = 0.75 +/- 0.07, evaluated from the changes of time integral). Both INa- and Ito-block was use- and frequency-dependent (20%-increase of INablock and 10%-increase of Ito-block under 0.3 and 10 μmol/l perphenazine, respectively, at the stimulation frequency of 3.3 Hz applied after a 15-s rest). The results of quantitative modelling suggest that perphenazine interacts with INa-channels in inactivated states, and with Ito-channels in both open and open-inactivated states.
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Využití MKP pro analýzu netradičního chlazení servo pohu
Vlach, Radek ; Pásek, Michal ; Grepl, Robert ; Krejčí, Petr
This project is concerned with non-convectional servo machine cooling using heat pipe. The aim was created computational model using finite elements method. The thermal model was built in software ANSYS 11. The thermal model using finite elements method was used for the check of such cooling. The aim was to examine the possibilities of using heat pipe for cooling of servo. The servo is possible overloaded using heat pipe, because heat pipe effectively reduces heating of machine.
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