DSpace Community: Elektronikos fakultetas / Faculty of Electronics
http://dspace.vgtu.lt:80/handle/1/5
Elektronikos fakultetas / Faculty of Electronics2021-05-03T13:02:44ZThe Application of a CMR-B-Scalar Sensor for the Investigation of the Electromagnetic Acceleration of Type II Superconductors
http://dspace.vgtu.lt:80/handle/1/4251
Title: The Application of a CMR-B-Scalar Sensor for the Investigation of the Electromagnetic Acceleration of Type II Superconductors
Authors: Vilius, Vertelis; Saulius, Balevičius; Voitech, Stankevič; Nerija, Žurauskienė; Markus, Schneider
Abstract: In this paper, we investigated the behavior of a type II superconducting armature when accelerated by a pulsed magnetic field generated by a single-stage pancake coil. While conducting this investigation, we performed a numerical finite element simulation and an experimental study of the magnetic field dynamics at the edge of the pancake coil when the payload was a superconducting disc made from YBa2Cu3O7−x, cooled down to 77 K. The magnetic field measurements were performed using a CMR-B-scalar sensor, which was able to measure the absolute magnitude of the magnetic field and was specifically manufactured in order to increase the sensor’s sensitivity up to 500 mT. It was obtained that type II superconducting armatures can outperform normal metals when the launch conditions are tailored to their electromagnetic properties.
Description: This article belongs to the Special Issue Magnetic Sensors and Systems for Scientific and Industrial Applications2020-12-31T22:00:00ZHexapod Robot Gait Switching for Energy Consumption and Cost of Transport Management Using Heuristic Algorithms
http://dspace.vgtu.lt:80/handle/1/4194
Title: Hexapod Robot Gait Switching for Energy Consumption and Cost of Transport Management Using Heuristic Algorithms
Authors: Luneckas, Mindaugas; Luneckas, Tomas; Kriaučiūnas, Jonas; Udris, Dainius; Plonis, Darius; Damaševičius, Robertas; Maskeliūnas, Rytis
Abstract: Due to the prospect of using walking robots in an impassable environment for tracked or wheeled vehicles, walking locomotion is one of the most remarkable accomplishments in robotic history. Walking robots, however, are still being deeply researched and created. Locomotion over irregular terrain and energy consumption are among the major problems. Walking robots require many actuators to cross different terrains, leading to substantial consumption of energy. A robot must be carefully designed to solve this problem, and movement parameters must be correctly chosen. We present a minimization of the hexapod robot’s energy consumption in this paper. Secondly, we investigate the reliance on power consumption in robot movement speed and gaits along with the Cost of Transport (CoT). To perform optimization of the hexapod robot energy consumption, we propose two algorithms. The heuristic algorithm performs gait switching based on the current speed of the robot to ensure minimum energy consumption. The Red Fox Optimization (RFO) algorithm performs a nature-inspired search of robot gait variable space to minimize CoT as a target function. The algorithms are tested to assess the efficiency of the hexapod robot walking through real-life experiments. We show that it is possible to save approximately 7.7–21% by choosing proper gaits at certain speeds. Finally, we demonstrate that our hexapod robot is one of the most energy-efficient hexapods by comparing the CoT values of various walking robots.
Description: This article belongs to the Special Issue Modelling and Control of Mechatronic and Robotic Systems2020-12-31T22:00:00ZOxidative Effects during Irreversible Electroporation of Melanoma Cells—In Vitro Study
http://dspace.vgtu.lt:80/handle/1/4175
Title: Oxidative Effects during Irreversible Electroporation of Melanoma Cells—In Vitro Study
Authors: Szlasa, Wojciech; Kielbik, Aleksander; Szewczyk, Anna; Rembialkowska, Nina; Novickij, Vitalij; Tarek, Mournir; Saczko, Jolanta; Kulbacka, Julita
Abstract: Irreversible electroporation (IRE) is today used as an alternative to surgery for the excision of cancer lesions. This study aimed to investigate the oxidative and cytotoxic effects the cells undergo during irreversible electroporation using IRE protocols. To do so, we used IRE-inducing pulsed electric fields (PEFs) (eight pulses of 0.1 ms duration and 2–4 kV/cm intensity) and compared their effects to those of PEFs of intensities below the electroporation threshold (eight pulses, 0.1 ms, 0.2–0.4 kV/cm) and the PEFs involving elongated pulses (eight pulses, 10 ms, 0.2–0.4 kV/cm). Next, to follow the morphology of the melanoma cell membranes after treatment with the PEFs, we analyzed the permeability and integrity of their membranes and analyzed the radical oxygen species (ROS) bursts and the membrane lipids’ oxidation. Our data showed that IRE-induced high cytotoxic effect is associated both with irreversible cell membrane disruption and ROS-associated oxidation, which is occurrent also in the low electric field range. It was shown that the viability of melanoma cells characterized by similar ROS content and lipid membrane oxidation after PEF treatment depends on the integrity of the membrane system. Namely, when the effects of the PEF on the membrane are reversible, aside from the high level of ROS and membrane oxidation, the cell does not undergo cell death.
Description: This article belongs to the Special Issue Novel Physical and Chemical Methods for Facilitated Drug Delivery2020-12-31T22:00:00ZMethod of Singular Integral Equations for Analysis of Strip Structures and Experimental Confirmation
http://dspace.vgtu.lt:80/handle/1/4173
Title: Method of Singular Integral Equations for Analysis of Strip Structures and Experimental Confirmation
Authors: Nickelson, Liudmila; Pomarnacki, Raimondas; Sledevič, Tomyslav; Plonis, Darius
Abstract: This paper presents a rigorous solution of the Helmholtz equation for regular waveguide structures with the finite sizes of all cross-section elements that may have an arbitrary shape. The solution is based on the theory of Singular Integral Equations (SIE). The SIE method proposed here is used to find a solution to differential equations with a point source. This fundamental solution of the equations is then applied in an integral representation of the general solution for our boundary problem. The integral representation always satisfies the differential equations derived from the Maxwell’s ones and has unknown functions μe and μh that are determined by the implementation of appropriate boundary conditions. The waveguide structures under consideration may contain homogeneous isotropic materials such as dielectrics, semiconductors, metals, and so forth. The proposed algorithm based on the SIE method also allows us to compute waveguide structures containing materials with high losses. The proposed solution allows us to satisfy all boundary conditions on the contour separating materials with different constitutive parameters and the condition at infinity for open structures as well as the wave equation. In our solution, the longitudinal components of the electric and magnetic fields are expressed in the integral form with the kernel consisting of an unknown function μe or μh and the Hankel function of the second kind. It is important to note that the above-mentioned integral representation is transformed into the Cauchy type integrals with the density function μe or μh at certain singular points of the contour of integration. The properties and values of these integrals are known under certain conditions. Contours that limit different materials of waveguide elements are divided into small segments. The number of segments can determine the accuracy of the solution of a problem. We assume for simplicity that the unknown functions μe and μh, which we are looking for, are located in the middle of each segment. After writing down the boundary conditions for the central point of every segment of all contours, we receive a well-conditioned algebraic system of linear equations, by solving which we will define functions μe and μh that correspond to these central points. Knowing the densities μe, μh, it is easy to calculate the dispersion characteristics of the structure as well as the electromagnetic (EM) field distributions inside and outside the structure. The comparison of our calculations by the SIE method with experimental data is also presented in this paper.
Description: This article belongs to the Section Mathematical Physics2020-12-31T22:00:00Z