@article{MTMT:34496311, title = {Dead-Time Effect in Inverters on Wireless Power Transfer}, url = {https://m2.mtmt.hu/api/publication/34496311}, author = {Rajs, Vladimir and Herceg, Dejana and Despotović, Živadin and Bogdanović, Miroslav and Šiljegović, Mirjana and Popadić, Bane and Kiraly, Zoltan and Vizvári, Zoltán Ákos and Sári, Zoltán and Klincsik, Mihály and Felde, Imre and Odry, Péter and Tadity, Vladimir}, doi = {10.3390/electronics13020304}, journal = {ELECTRONICS (SWITZ)}, volume = {13}, unique-id = {34496311}, abstract = {This paper presents a comprehensive analysis of the dead-time effects in wireless power transfer systems based on LCC-S topology. In these systems operating at high frequencies, the ratio of dead-time versus the operating period becomes critical, and the dead-time issue can cause certain problems regarding power quality, efficiency, and output voltage ripple. The impact of input quantities such as voltage and switching frequency on the efficiency and output power of the LCC-S-tuned WPT system was also investigated. The optimal combination of these parameters used to achieve the maximum efficiency for a target output power and to set the appropriate value of the dead time were determined by running multiple simulations using the MATLAB R2023b software platform. It was also shown that the output voltage remained unchanged with and without a load and up to 1200 ns of dead-time, which provides a simple implementation of the corresponding mathematical model. In the recommended interval of 600–1500 ns, the influence of the dead-time on the value of the output voltage amplitude is less than 10%. The validity of the proposed method was confirmed through the implementation of the experimental prototype, a 5 kW wireless power transmission system, and the obtained results were in accordance with the simulation results.}, year = {2024}, eissn = {2079-9292}, orcid-numbers = {Rajs, Vladimir/0000-0003-4357-770X; Despotović, Živadin/0000-0001-7277-9453; Kiraly, Zoltan/0000-0002-6808-3856} } @article{MTMT:34448557, title = {Continuous Electrode Models and Application of Exact Schemes in Modeling of Electrical Impedance Measurements}, url = {https://m2.mtmt.hu/api/publication/34448557}, author = {Vizvári, Zoltán Ákos and Klincsik, Mihály and Odry, Péter and Tadity, Vladimir and Győrfi, Nina Rubina and Tóth, Attila and Sári, Zoltán}, doi = {10.3390/electronics13010066}, journal = {ELECTRONICS (SWITZ)}, volume = {13}, unique-id = {34448557}, abstract = {The crucial issue in electrical impedance (EI) measurements lies in the galvanic interaction between the electrodes and the investigated material. This paper brings together the basic and applied research experience and combines their results with excellent properties. Consequently, innovative precise methodologies have emerged, enabling the direct modeling of EI measurements, free from the inaccuracies often associated with numerical approaches. As an outcome of the efficiency and robustness of the applied method, the conductivity of the material and the electrodes are represented by a common piecewise function, which is used to solve the differential equation modeling of the EI measurement. Moreover, this allows the possibility for modeling the conductivity of electrodes with continuous functions, providing an important generalization of the Complete Electrode Model (CEM), which has been widely used so far. The effectiveness of the novel approach was showcased through two distinct case studies. In the first case study, potential functions within both the material and the electrodes were computed using the CEM. In the second case study, calculations were performed utilizing the newly introduced continuous electrode model. The simulation results suggest that the new method is a powerful tool for biological research, from in vitro experiments to animal studies and human applications.}, year = {2024}, eissn = {2079-9292} } @article{MTMT:34124226, title = {Novel Noninvasive Paraclinical Study Method for Investigation of Liver Diseases}, url = {https://m2.mtmt.hu/api/publication/34124226}, author = {Győrfi, Nina Rubina and Gál, Adrián Róbert and Fincsur, András and Kalmar-Nagy, Karoly and Mintál, Kitti and Hormay, Edina and Miseta, Attila János and Tornóczky, Tamás and Nemeth, Anita K. and Bogner, Péter and Kiss, Tamas and Helyes, Zsuzsanna and Sári, Zoltán and Klincsik, Mihály and Tadity, Vladimir and Lénárd, László and Vereczkei, András and Karádi, Zoltán György and Vizvári, Zoltán Ákos and Tóth, Attila}, doi = {10.3390/biomedicines11092449}, journal-iso = {BIOMEDICINES}, journal = {BIOMEDICINES}, volume = {11}, unique-id = {34124226}, abstract = {Based on a prior university patent, the authors developed a novel type of bioimpedance-based test method to noninvasively detect nonalcoholic fatty liver disease (NAFLD). The development of a new potential NAFLD diagnostic procedure may help to understand the underlying mechanisms between NAFLD and severe liver diseases with a painless and easy-to-use paraclinical examination method, including the additional function to detect even the earlier stages of liver disease. The aim of this study is to present new results and the experiences gathered in relation to NAFLD progress during animal model and human clinical trials.}, keywords = {VALIDATION; clinical study; hepatic steatosis; Wistar; Bioelectrical impedance spectroscopy; NAFLD; noninvasive measurement; low-frequency measurement}, year = {2023}, eissn = {2227-9059}, orcid-numbers = {Mintál, Kitti/0009-0003-4739-2902; Hormay, Edina/0009-0004-0598-5061; Miseta, Attila János/0000-0002-7984-3347} } @article{MTMT:34037447, title = {General Exact Schemes for Second-Order Linear Differential Equations Using the Concept of Local Green Functions}, url = {https://m2.mtmt.hu/api/publication/34037447}, author = {Vizvári, Zoltán Ákos and Klincsik, Mihály and Odry, Péter and Tadity, Vladimir and Sári, Zoltán}, doi = {10.3390/axioms12070633}, journal-iso = {AXIOMS}, journal = {AXIOMS}, volume = {12}, unique-id = {34037447}, abstract = {In this paper, we introduce a special system of linear equations with a symmetric, tridiagonal matrix, whose solution vector contains the values of the analytical solution of the original ordinary differential equation (ODE) in grid points. Further, we present the derivation of an exact scheme for an arbitrary mesh grid and prove that its application can completely avoid other errors in discretization and numerical methods. The presented method is constructed on the basis of special local green functions, whose special properties provide the possibility to invert the differential operator of the ODE. Thus, the newly obtained results provide a general, exact solution method for the second-order ODE, which is also effective for obtaining the arbitrary grid, Dirichlet, and/or Neumann boundary conditions. Both the results obtained and the short case study confirm that the use of the exact scheme is efficient and straightforward even for ODEs with discontinuity functions.}, year = {2023}, eissn = {2075-1680} } @article{MTMT:33787514, title = {Lumped Element Method Based Conductivity Reconstruction Algorithm for Localization Using Symmetric Discrete Operators on Coarse Meshes}, url = {https://m2.mtmt.hu/api/publication/33787514}, author = {Sári, Zoltán and Klincsik, Mihály and Odry, Péter and Tadity, Vladimir and Tóth, Attila and Vizvári, Zoltán Ákos}, doi = {10.3390/sym15051008}, journal-iso = {SYMMETRY-BASEL}, journal = {SYMMETRY (BASEL)}, volume = {15}, unique-id = {33787514}, abstract = {The inverse conductivity problem in electrical impedance tomography involves the solving of a nonlinear and under-determined system of equations. This paper presents a new approach, which leads to a quadratic and overdetermined system of equations. The aim of the paper is to establish new research directions in handling of the inverse conductivity problem. The basis of the proposed method is that the material, which can be considered as an isotropic continuum, is modeled as a linear network with concentrated parameters. The weights of the obtained graph represent the properties of the discretized continuum. Further, the application of the developed procedure allows for the dielectric constant to be used in the multi-frequency approach, as a result of which the optimized system of equations always remains overdetermined. Through case studies, the efficacy of the reconstruction method by changing the mesh resolution applied for discretizing is presented and evaluated. The presented results show, that, due to the application of discrete, symmetric mathematical structures, the new approach even at coarse mesh resolution is capable of localizing the inhomogeneities of the material.}, year = {2023}, eissn = {2073-8994} } @article{MTMT:33236539, title = {A competition system with nonlinear cross-diffusion: exact periodic patterns}, url = {https://m2.mtmt.hu/api/publication/33236539}, author = {Kersner, Róbert and Klincsik, Mihály and Zhanuzakova, Dinara}, doi = {10.1007/s13398-022-01299-1}, journal-iso = {RACSAM REV R ACAD A}, journal = {REVISTA DE LA REAL ACADEMIA DE CIENCIAS EXACTAS FISICAS Y NATURALES SERIE A-MATEMATICAS}, volume = {116}, unique-id = {33236539}, issn = {1578-7303}, abstract = {Our concern in this paper is to shed some additional light on the mechanism and the effect caused by the so called cross-diffusion. We consider a two-species reaction-diffusion (RD) system. Both "fluxes" contain the gradients of both unknown solutions. We show that-for some parameter range- there exist two different type of periodic stationary solutions. Using them, we are able to divide into parts the (eight-dimensional) parameter space and indicate the so called Turing domains where our solutions exist. The boundaries of these domains, in analogy with "bifurcation point", called "bifurcation surfaces". As it is commonly believed, these solutions are limits as t goes to infinity of the solutions of corresponding evolution system. In a forthcoming paper we shall give a detailed account about our numerical results concerning different kind of stability. Here we also show some numerical calculations making plausible that our solutions are in fact attractors with a large domain of attraction in the space of initial functions.}, keywords = {pattern formation; Periodic stationary solutions; Stability of patterns; Cross-diffusion; Reaction-diffusion (RD )systems}, year = {2022}, eissn = {1579-1505} } @inproceedings{MTMT:32732764, title = {Heurisztikus optimalizálás alkalmazása a bioimpedancia spektroszkópiás kiértékelésben}, url = {https://m2.mtmt.hu/api/publication/32732764}, author = {Odry, Ákos and Vizvári, Zoltán Ákos and Győrfi, Nina Rubina and Kovács, Levente and Eigner, György and Klincsik, Mihály and Sári, Zoltán and Odry, Péter and Tóth, Attila}, booktitle = {Orvosbiológiai kérdések - multidiszciplináris, bioimpedancia alapú válaszok}, unique-id = {32732764}, year = {2022}, pages = {21-34}, orcid-numbers = {Kovács, Levente/0000-0002-3188-0800} } @article{MTMT:32718606, title = {Perspectives of RealSense and ZED Depth Sensors for Robotic Vision Applications}, url = {https://m2.mtmt.hu/api/publication/32718606}, author = {Tadity, Vladimir and Tóth, Attila and Vizvári, Zoltán Ákos and Klincsik, Mihály and Sári, Zoltán and Sarcevic, Péter and Sárosi, József and Bíró, István}, doi = {10.3390/machines10030183}, journal-iso = {MACHINES}, journal = {MACHINES}, volume = {10}, unique-id = {32718606}, abstract = {This review paper presents an overview of depth cameras. Our goal is to describe the features and capabilities of the introduced depth sensors in order to determine their possibilities in robotic applications, focusing on objects that might appear in applications with high accuracy requirements. A series of experiments was conducted, and various depth measuring conditions were examined in order to compare the measurement results of all the depth cameras. Based on the results, all the examined depth sensors were appropriate for applications where obstacle avoidance and robot spatial orientation were required in coexistence with image vision algorithms. In robotic vision applications where high accuracy and precision were obligatory, the ZED depth sensors achieved better measurement results.}, keywords = {Depth Map; Robotics applications; Depth sensors; RealSense}, year = {2022}, eissn = {2075-1702}, orcid-numbers = {Sarcevic, Péter/0000-0003-4050-8231; Sárosi, József/0000-0002-6303-5011; Bíró, István/0000-0002-3223-6558} } @article{MTMT:32149186, title = {Lumped Element Method. A Discrete Calculus Approach for Solving Elliptic and Parabolic PDEs}, url = {https://m2.mtmt.hu/api/publication/32149186}, author = {Vizvári, Zoltán Ákos and Klincsik, Mihály and Sári, Zoltán and Odry, Péter}, doi = {10.12700/APH.18.7.2021.7.11}, journal-iso = {ACTA POLYTECH HUNG}, journal = {ACTA POLYTECHNICA HUNGARICA}, volume = {18}, unique-id = {32149186}, issn = {1785-8860}, year = {2021}, eissn = {1785-8860}, pages = {201-223} } @inproceedings{MTMT:32092177, title = {Application of Heuristic Optimization in Bioimpedance Spectroscopy Evaluation}, url = {https://m2.mtmt.hu/api/publication/32092177}, author = {Odry, Ákos and Vizvári, Zoltán Ákos and Győrfi, Nina Rubina and Kovács, Levente and Eigner, György and Klincsik, Mihály and Sari, Zoltan and Odry, Péter and Tóth, Attila}, booktitle = {15th IEEE International Symposium on Applied Computational Intelligence and Informatics SACI 2021}, doi = {10.1109/SACI51354.2021.9465617}, unique-id = {32092177}, abstract = {As material analysis method, the bioimpedance spectroscopy (BIS) is an effective technique to obtain material characteristics in many biological applications. Among the BIS models, the single-dispersion RC model and the Cole-Cole model constitute the fundamental mathematical descriptions for BIS measurements. These models enable both the evaluation of impedance spectrum and derivation of core parameters that describe biological processes. This paper presents the application of the particle swarm optimization (PSO), as a flexible heuristic optimization approach, to both derive the model parameters and characterize biological media based on BIS measurements. First, the fundamental modeling approaches are addressed and the core parameters arc discussed. Moreover, the employed electrical impedance measuring instrument and conducted experiments are presented. Then, a multi-objective fitness function is established for the usage of the PSO algorithm for model parameter optimization. The paper demonstrates two case studies, namely, BIS measurements are performed to monitor i) liver fat and characterize its state with an optimized Cole-Cole model and ii) cell culture growth and characterize its state with an optimized single-dispersion RC model. It is shown with experimental results that PSO is an effective and robust tool to fit these biological models to BIS measurements. Additionally, the experimental results also highlight that the cell culture growth process cannot be modeled properly with the single-dispersion RC model in high frequency ranges. This experimental observation establishes the demand for the derivation of a more sophisticated mathematical model for the comprehensive characterization of cell culture growth in wide frequency spectrum.}, year = {2021}, pages = {000105-000112}, orcid-numbers = {Kovács, Levente/0000-0002-3188-0800} }