Ústav teoretické a experimentální elektrotechniky

Browse

Now showing 1 - 5 of 65

Polymerization mechanisms of hexamethyldisiloxane in low-pressure plasmas involving complex geometries
(ELSEVIER, 2024-02-01) Navascues, Paula; Janůšová, Martina; Zajíčková, Lenka; Rupper, Patrick; Hegemann, Dirk
Hexamethyldisiloxane (HMDSO) low-pressure plasmas are known for their versatility in the deposition of plasma polymer films (PPFs) with different properties and applications. Although they have been studied for decades, the reaction mechanisms of plasma polymer formation leave open questions, particularly when deposition on 3D materials with complex geometries such as cavities and undercuts is considered. In the present study, two configurations named "cavity" and "undercut" have been selected to study the influence of diffusion of film forming species and surface reactivity in HMDSO plasmas without and with O2 admixture. A varying spatial chemical composition of the plasma polymer deposit along the penetration depth of the studied configurations indicates different sticking probabilities of the film-forming species. Furthermore, although ion-induced effects are usually only considered for direct plasma exposure, the obtained results and additional etching experiments reveal that the contribution of high-energy particles might still be considered underneath small openings. Finally, the relevance of oxidizing chemical reactions at the surface inside the configurations is clarified when O2 is added to the plasma.
Wireless Multi-Coil Transmission With a Rotating Part of the Internal Winding
(IEEE, 2024-10-24) Pokorný, Josef; Dohnal, Přemysl; Marcoň, Petr
This article discusses the basic principles of concentrating the radiated near non-radiant magnetic field by changing the angle of the winding sector of the spiral coils designed on a substrate for a standard PCB (printed circuit board). The relevant principles include: 1) Changing the shape and design of the movable inner part of the coil winding; together with the static part, the moving item can form a concentrated magnetic field in space, thus creating a magnetic vector. 2) The 2x2 matrix of these coils comprises individual resonators changing the shape of the magnetic field according to the shape, distance, and position of the receiver. Thus, the concentrated individual vectors of the field are formed by the current amplitude, azimuth, and elevation of the individual coils. Using a spare electrical circuit, we implemented the entire concept relying on the shape of the coils. This method is materialized on a hardware prototype.
Measurement and Evaluation of Insulating Properties of a Modified Dielectric Surface using Plasma Discharge
(Sciendo, 2024-12-01) Pernica, Roman; Klíma, Miloš; Fiala, Pavel
Plasma discharges under atmospheric pressure can be used to modify the electrical properties of metallic and dielectric surfaces. The aim of such a modification is to achieve an improvement in the characteristic parameters of the surface, for example in the area of the electrical strength of the surface, in order to achieve a higher ultimate level of electrical breakdown Eb when tested with pulsed or alternating electrical voltages. So far, research has focused on a set of functional experiments carried out using plasma on samples of two types of dielectric materials (thermoset, thermoplastic) with an impact on the final effect of the level of electrical breakdown voltage, electrical intensity and Eb. surface conductivity. The treatment technology requires repeatability and consideration of the industrial deployment conditions of plasma technology. The surface structure was modified in a defined and repeatable way by plasma discharge under atmospheric pressure without the presence of precursors. Methods to evaluate these modifications assessed the change in parameters related to sample type, repeatability and prediction of treatment stability. Subsequently, the surface strength of both the modified samples and the samples not affected by the plasma discharge was measured.
Alternative Energy Sources Usable in Automotive Transport
(MDPI, 2024-12-18) Zukal, Jiří; Szabó, Zoltán; Klíma, Miloš; Fiala, Pavel
The research focuses on the methodology of preparing a concept and application scenarios for al-ternative sources of energy in transportation. The ideas and interpretations are not strictly limited to automobile transport but also reach into other areas of using and processing energy. The conceptual approach to the choice of sources, with the aim of securing the efficient use of energy conversion, is illustrated on the model embodiment embedded in a passenger car; the relevant presentation is centered on an experiment focusing on the linear arrangement of a driven elec-tromagnetic generator. This involves generating and collecting energy for not only the accumula-tion of electrical energy using relatively independent systems, but also for direct use within driv-ing needs. In the modeled example, the supplied energy is assumed to be in a range of constant power from P = 10 W to 50 kW (200 kW). The given example of the design of the choice of energy conversion sources and the use of generators in a passenger car shows the possibilities, limitations, and variants for demonstrating the requirements relating to a simple driving mode. The application of a linear or cylindrical internal combustion engine is considered for a specific set mode of the car. Variants of suitable uses of the accumulated energy in compressed air are pro-posed. The use of light and thermal forms of energy is considered for additional forms. As an ex-perimental example, the use of generators derived from vibration harvesters is shown. The pro-posed energy generation arrangement can be controlled and optimized for specific transport tasks. The generation and accumulation of energy can be employed in the form of electrical ener-gy, as kinetic energy for direct use in driving , or to accumulate in compressed air for later use. Solar energy can be used directly or can be accumulated. The combustion unit can serve as a source of kinetic energy or also to store energy for further use. The concept of alternative sources is based on known methods of use in other industries. The model combination of resources and its simple analysis in the concept of resource selection is demonstrated on an example of an application in passenger cars.
Enhanced Image Reconstruction in Electrical Impedance Tomography using Radial Basis Function Neural Networks
(Sciendo, 2024-12-16) Kouakouo Nomvussi, Serge Ayme; Mikulka, Jan
This paper presents a novel cascade algorithm for image reconstruction in electrical impedance tomography (EIT) using radial basis function neural networks. The first subnetwork applies a density-based algorithm and k-nearest neighbors (KNN) to determine the center and width of the radial basis function neural networks, with the aim of preventing ill-conditioned connection weights between the hidden and output layers. The second subnetwork is a generalized regression neural network dedicated to functional approximation. The combined subnetworks result in a reduced mean square error and achieve an accuracy of 89.54 % without noise and an accuracy between 82.90 % and 89.53 % with noise levels ranging from 30 to 60 dB. In comparison, the original radial basis function neural networks (RBFNN) method achieves an accuracy of 85.44 % without noise and between 80.90 % and 85.31 % under similar noise conditions. The total variation (TV) method achieves 83.13 % without noise, with noise-influenced accuracy ranging from 34.28 % to 45.15 %. The Gauss-Newton method achieves 82.35 % accuracy without noise, with accuracy ranging from 33.21 % to 46.15 % in the presence of noise. The proposed method proves to be resilient to various types of noise, including white Gaussian noise, impulsive noise, and contact noise, and consistently delivers superior performance. It also outperforms the other methods in noise-free conditions. The reliability of the method in noisy environments supports its potential application in the development of new modular systems for electrical impedance tomography.

Browse

Recent Submissions