Ústav výkonové elektrotechniky a elektroniky
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- ItemMathematical modeling of the effect of stent construction during endoluminal IRE for recanalization of an occluded metal stent(Taylor & Francis, 2025-07-02) Matkulčík, Peter; Hemzal, Martin; Rohan, Tomáš; Červinka, Dalibor; Novotná, Veronika; Nahum Goldberg, Shraga; Andrašina, TomášBackground: Intraluminal irreversible electroporation (IRE) can be used for recanalizing occluded metalstents. However, optimal IRE parameters for consistent effects across different stent designs remainunclear. The aim of this study was to simulate the process of stent recanalization in silico by employingfinite element analysis. Methods: A virtual model of an occluded biliary stent with an experimental 3-electrode IRE catheter was developed. Electric field distribution, temperature changes, and potential ablation volumes weresimulated across various parameters: IRE voltage (300 1300 V), stent wire width (0.1 0.5 mm) and stentmesh size (0.7 5.58 mm). Simulations incorporated five representative stent types commonly used inclinical practice. 685 unique simulations were conducted, analyzing 1162 unique values. Results: Higher voltages generally led to larger ablation zones and increased temperatures. Thinnerstent wires and larger mesh sizes also increased the extent of ablation zone. While in-stent ablation waslargely independent of stent design, out-of-stent ablation was significantly impacted by mesh size andtissue thickness between the stent and irreversible electroporation electrodes. Voltages above 1000 Vproduced significant thermal effects, with substantial volumes of tissue heated above 50 °C. Specificstent designs exhibited variations in maximum temperature (72.1 83.1 °C) and ablation volume(8.7 14.7 mm3). Conclusion: Tailored IRE protocols for different stent designs are required due to differences in in- andout-stent ablation volumes. High voltages (>1000 V) induce both thermal and nonthermal ablation mechanisms.
- ItemThree-Phase AC/DC Quasi-Single-Stage Isolated Resonant PFC Converter With Integrated Transformer(IEEE, 2024-05-30) Martiš, Jan; Vorel, Pavel; Tománek, Radek; Bauer, PavolConverters that produce an isolated dc output from a three-phase mains supply are often required. Moreover, input power factor correction (PFC) functionality is essential. A standard two-stage conception with ac/dc and dc/dc converters may be used. However, a single-stage or quasi-single-stage solution can simplify the circuitry and increase efficiency; therefore, many variants of single-stage converters have been researched and published. This paper introduces a novel quasi-single-stage resonant topology with an integrated transformer. Additionally, an original control structure is proposed. This converter enables full control over the output dc voltage and current. Another benefit of the proposed converter is a relatively low complexity of its power circuit and control compared to other single-stage converters. The operation principle of the power circuit is explained and the control strategy is also analyzed in detail. A description of the integrated transformer together with aspects of the resonant circuit design are presented. A simulation of the entire converter was performed and evaluated. Furthermore, a test-bench prototype was designed and constructed and is outlined in this paper. The test-bench measurement results are provided and compared to the simulation results. Power factor and efficiency measurements in terms of their dependence on the output voltage and current are included.
- ItemPower Curve Determination and Electrification of Powertrain System of Harvester Crane Swinging(University of Zagreb, Faculty of Forestry and Wood Technology, 2024-08-18) Mergl, Václav; Procházka, Petr; Nagy, Miroslav; Zeizinger, Lukáš; Vítek, Ondřej; Gulan, LadislavThe work deals with the determination of the power curve for driving the swinging of the hydraulic crane of the harvester and the subsequent replacement of the hydraulic motor with an electric motor for the possibility of recuperating braking energy. For this purpose, the hydraulic circuit of the crane slewing gear was measured with flowmeters during its rotation between the angles –105° to +105°, –90° to +90° and –36° to +22°. The power was calculated from the measured values. The maximum power needed to swing the harvester crane was 9720 W. With this power, the torque reached 187.98 Nm. The average value of the power needed to swing the hydraulic crane was only 2472 W at a torque of 47.81 Nm. From these values, a synchronous electric motor with permanent magnets with a nominal speed of 2000 rpm (rotation per minute) and a power of 3246 W emerged as suitable for replacing the hydraulic motor. The use of an electric motor would, however, require a planetary gearbox with fast input speeds that would then be reduced to slow output speeds. The research results demonstrated the possibility of using an electric motor to swing the hydraulic crane during the work cycle of the harvester for the use of energy recovery from crane braking and thus the possibility of reducing fuel consumption and emissions.
- ItemOPTICAL EMISSION SPECTROSCOPY OF BREAKING ARC PLASMA BETWEEN CONSUMABLE ELECTRODES(Department of Physics, FEE CTU in Prague, 2024-12-03) Murmantsev, Aleksandr; Bartlová, Milada; Šimek, David; Valenta, Jiří; Kloc, Petr; Apanasenko, V.The investigation focuses on the optical emission spectroscopy of plasma generated by breaking arc between single-component Cu and composite Cu-W electrodes manufactured using shock sintering technology at temperature of 750°C. The electrodes were subjected to arc currents of 4, 50, and 104A. Optical emission spectroscopy with high spectral and temporal resolution was employed to investigate the plasma with copper and tungsten vapour admixtures. The temporal evolution of temperature in the plasma was determined by the Boltzmann plot technique based on the emission intensities of CuI spectral lines. Temporal evolution of electron densities were determined from the full width at half maximum of CuI 515.3nm spectral line. These initial plasma parameters integrated over the volume of breaking arc were utilized to calculate the temporal evolution of plasma compositions and contents of metal vapours admixtures in discharge gap.
- ItemSample Thickness and Edge Proximity Influence Spatial Behavior of Filaments and Treatment Uniformity of RF Cold Atmospheric Pressure Plasma Jet(SPRINGER, 2025-01-01) Polášková, Kateřina; Nečas, David; Dostál, Lukáš; Klíma, Miloš; Zajíčková, LenkaThe ability of atmospheric pressure plasma jets to treat complex non-planar surfaces is often cited as their advantage over other atmospheric plasmas. However, the effect of complex surfaces on plasma parameters and treatment efficiency has seldom been studied. Herein, we investigate the interaction of the atmospheric pressure plasma slit jet (PSJ) with block polypropylene samples of different thicknesses (5 and 30 mm) moving at two different speeds. Even though the distance between the slit outlet and the sample surface was kept constant, the treatment efficiency of PSJ ignited in the Ar and Ar/O2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {Ar/O}_2$$\end{document} gas feeds varied with the sample thickness due to the plasma parameters such as filament count and speed being affected by the different distances of the ground (the closer the ground is, the higher the discharge electric field). On the other hand, the Ar/N2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {Ar/N}_2$$\end{document} PSJ diffuse plasma plumes were less affected by the changes in the electric field, and the treatment efficiency was the same for both sample thicknesses. Additionally, we observed a difference in the efficiency and uniformity of the PSJ treatment of the edges and the central areas in some working conditions. The treatment efficiency near the edges depended on the duration of the filament contact, i. e., how long the local electric field trapped the filaments. Conversely, the treatment uniformity near the edges and in the central areas was different if the number of filaments changed rapidly as the discharge moved on and off the sample (the 5 mm samples treated by easily sustained Ar PSJ).