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Multiple Indoor Robot Localization Using Infrared Beacons
Krejsa, Jiří ; Věchet, Stanislav ; Chen, K.-S.
Mobile robot localization based on active artificial landmarks is well established robust technique in indoor mobile robotics. This paper explores the extension of the method to multiple robot localization, with the key idea of using the robots themselves as the artificial landmarks, supplying other robots in the group with its estimate of position. The method uses nonlinear version of Kalman filter for determination of position estimate in 2D space, x-y coordinates and angle with respect to global coordinate system, with the estimate represented by mean values and corresponding covariances. Simulation results based on model well verified with the real system suggest that while only small reduction of number of fixed active landmarks can be achieved, the main advantage of the method is in increased robustness of localization technique with respect to obscured landmarks fields of view.
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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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Concentration distribution of coarse-grained particle-water mixture in horizontal pipe
Vlasák, Pavel ; Chára, Zdeněk ; Konfršt, Jiří ; Krupička, Jan
The paper describes the results of coarse-grained particle-water mixture measurements in an experimental pipeline loop of inner diameter 100 mm. Graded basalt pebbles of mean diameter 11 mm, conveyed by water, were investigated. The concentration distribution measurements were carried out with application of gamma-ray based device. Presented results refer to the effect of mixture velocity and overall concentration on chord-averaged concentration and local concentration distribution in the horizontal pipe. The study revealed that the coarse-grained particle-water mixtures were significantly stratified, solid particles moved principally close to the pipe invert, for higher and moderate flow velocities saltation becomes dominant mode of the sediment transport.
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Simulation of motion of multiple particles in a closed conduit using the LBM based approach
Dolanský, Jindřich
The two-dimensional numerical model of motion of multiple circular particles in fluid flow based on the lattice Boltzmann method (LBM) is presented. The flow is driven by the power-law velocity profile at the inlet in a closed horizontal conduit. Motion of particles consists of free motion in the flow, particle-bed and particle-particle collisions. The simulation for both movements of particles and velocity field of the flow is developed. Stability issues of the simulation are considered and a resolution using the entropic LBM and extension of computational resources is proposed. Finally, an enhancement of the simulation for more complex processes is suggested
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