1. Procedure for the determination of the appropriate protective foil size to reduce step voltage using a FEM model and evolutionary methodsMarko Jesenik, Peter Kitak, Robert Maruša, Janez Ribič, 2025, original scientific article Abstract: When a fault occurs in a power transmission system, voltages that are dangerous to people may occur. The aim of this work is to present the following method of protection: the use of protective foil installed at the appropriate depth around the transmission pole. Moreover, a procedure is presented for determining the optimal size of the protective film using a minimum number of finite element method calculations. In addition to the finite element method, evolutionary methods are used to determine the appropriate coefficients. Real earthing system data, earth data, and the fault current are obtained from the Slovenian system operator (ELES, d.o.o.) and used exclusively in the presented analyses. The results of determining the appropriate size of the protective foil for two transmission poles are presented, and the determination of the required breakthrough strength of the materials used is shown. The suitability of the proposed method is confirmed. This method is practical and useful when protection with protective foil is required, ensuring only as much as necessary is applied.
Keywords: transmission system, touch voltage, touch voltage, step voltage, grounding system, differential evolution, artificial bee colony, teaching–learning-based optimization
Published in DKUM: 23.04.2025; Views: 0; Downloads: 0
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2. Contactless determination of a permanent magnet’s stable position within ferrofluidMislav Trbušić, Anton Hamler, Viktor Goričan, Marko Jesenik, 2022, original scientific article Abstract: The paper deals with the contactless detection of a rod permanent magnet’s position within
a ferrofluid. The working principle of the proposed approach is grounded on the solenoidal nature of
the field lines. For the line detection technique analyzed in this article, where the magnetic field is
scanned along the line parallel to the magnet’s axial direction, the center of the magnet corresponds
to the point on the line where the radial component of the magnetic field vanished. The concept
introduced here was evaluated numerically, where the results showed a promising perspective for
the technique to be employed in practice. In contrast to the X-ray or Vernier-caliper-based technique,
the one proposed here is somewhat more suitable for employment in applications where simplicity
and robustness are of vital importance.
Keywords: permanent magnet, levitation, ferrofluid, magnetic sensor, magnetic field, finite element method, FEM
Published in DKUM: 28.03.2025; Views: 0; Downloads: 3
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3. The approach of using a horizontally layered soil model for inhomogeneous soil, by taking into account the deeper layers of the soil, and determining the model’s parameters using evolutionary methodsMarko Jesenik, Mislav Trbušić, 2025, original scientific article Abstract: A new approach using a horizontally layered analytical soil model for inhomogeneous soil is presented. The presented approach also considers deeper soil layers, which is not the case when simply dividing the area of interest into smaller subareas. The finite element method model was used to prepare test data because, in such a case, the soil parameters are known. Six lines simulating Wenner’s method were used, and their results were combined appropriately to determine the soil parameters of nine subareas. To determine the soil parameters in the scope of each subarea, different optimization methods were used and compared to each other. The results were analyzed, and Artificial Bee Colony was selected as the most appropriate method among those tested. Additionally, the convergence of the methods was analyzed, and Memory Assistance is presented, with the aim of shortening the calculation time. In this study, three-, four-, five-, and six-layered soil models were tested, and it is concluded that the three-layered model is most appropriate. A finite element method model based on the soil determination results was constructed to verify the results. The results of the Wenner’s method simulation in the cases of the test data and final model were compared to confirm the accuracy of the presented method
Keywords: grounding system, soil model, finite element method, differential evolution, artificial bee colony, teaching–learning-based optimization
Published in DKUM: 21.02.2025; Views: 0; Downloads: 3
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4. Tradicionalni in družbeni mediji v času pandemije CovidaAja Jesenik, 2024, undergraduate thesis Abstract: Diplomsko delo je teoretična in empirična raziskava o tradicionalnih in družbenih medijih v času pandemije covid. Diplomsko delo predstavlja vpliv pandemije covid na delovanje tradicionalnih in družbenih medijev. Teoretični del temelji na predstavitvi razumevanja družbenih in tradicionalnih medijev, virusa in pandemije covid. Pričakovano je bilo, da je pandemija covid močno vplivala na način delovanja medijev, zato je bilo raziskano, kako so se morali mediji prilagoditi, da so lahko ostali na trgu. Predstavljene so spremembe, ki so jih morebiti uvedli, če so jih uvedli. V praktičnem delu je predstavljen intervju s petimi predstavniki slovenskih medijskih hiš. Ugotovljeno je bilo, da so se medijske hiše prilagodile glede na pogoje, ki jih je uvedla Vlada Republike Slovenije. Po zaključeni pandemiji se je delovanje medijev vrnilo v prvotno stanje. Mediji se prilagajajo in razvijajo glede na trg. Pandemija covid ni imela tako velikega vpliva na medije, kot je bilo predvidevano, je pa pripomogla k hitrejšemu razvoju medijev.
Keywords: tradicionalni mediji, družbeni mediji, pandemija covid, vpliv pandemije, spremembe
Published in DKUM: 08.08.2024; Views: 196; Downloads: 40
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5. Izračun elektromagnetnega polja v okolici ozemljitvenega sistema ob udaru strele : magistrsko deloDanilo Osojnik, 2024, master's thesis Abstract: V magistrskem delu smo analizirali električni potencial in napetost koraka na površini zemlje v prisotnosti ozemljitvene mreže. To smo storili tako, da smo najprej določili enoplastni in triplastni model zemlje. Podatke za določitev modelov smo pridobili iz meritev, pri čemer smo uporabili Wennerjevo metodo. Enoplastni model smo določili iz povprečja izmerjenih vrednosti specifične upornosti, medtem ko smo triplastni model določili s pomočjo optimizacijskih metod. Nato smo v programu Flux 3D izdelali različne modele zemlje z ozemljitveno mrežo. Ta je imela različno gostoto in se je nahajala na treh različnih globinah. Na opisanih modelih smo simulirali udar strele in analizirali potencial na površini in v globini zemlje. Iz potencialov smo izračunali napetost koraka in jo za obravnavane scenarije med seboj primerjali.
Keywords: Prenapetosti, ozemljitvena mreža, potencial, napetost koraka
Published in DKUM: 02.07.2024; Views: 145; Downloads: 99
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6. REKONSTRUKCIJA VALJČNE PROGE 800 V ŠTORE STEEL : diplomsko deloGregor Pusar, 2024, undergraduate thesis Abstract: Diplomsko delo obravnava rekonstrukcijo valjčne proge 800 v podjetju Štore Steel, ki jo je izvedlo podjetje ETRA, d. o. o. V osnovi gre za krmiljenje asinhronskih motorjev, ki so ostali nespremenjeni od začetka delovanja proge. Proga 800 uporablja 16 asinhronskih motorjev, pri čemer je prvotno en pretvornik krmilil osem asinhronskih motorjev (pretvornik ASEA tip »YRYB«), tj. pretvornik ASEA tip »YRYB«, ki je bil v uporabi ob zagonu stroja. Pretvornik ASEA tip »YRYB« je bil sprva najustreznejša rešitev, nato pa se je pojavila težava z vzdrževanjem, saj je bila elektronika draga in težavna za pridobiti, predvsem zaradi pomanjkanja rezervnih delov. Prva faza prenove je vključevala postopno demontažo obstoječih pretvornikov ASEA in namestitev pretvornikov SIMOVERT MASTERDRIVES Vector Control. Ta izvedba je težavna za vzdrževanje, saj če odpove samo en segment (DC-link), so štirje motorji v napaki. Kljub temu da je ta izvedba težavna za vzdrževanje, je bila v tistem času najboljša možna rešitev. Prav zaradi tega je sledila nadaljnja zamenjava za Sinamics S120, ki krmili štiri asinhronske motorje. Ta izvedba je prav tako predstavljala izzive za vzdrževanje, saj je odpoved enega segmenta (DC-link) povzročila napako pri štirih asinhronskih motorjev, podobno kot pri SIMOVERT MASTERDRIVES Vector Control. Končna faza prenove je vključevala uporabo pretvornikov Sinamics G120C. Vsak asinhronski motor je dobil svoj pretvornik, kar je omogočilo izboljšano vzdrževanje in boljšo diagnostiko. Morebitna okvara enega pretvornika ni več vplivala na celotno proizvodnjo in proizvodni proces. Delo prav tako podrobno opisuje postopek optimizacije pretvornika Sinamics G120C z uporabo programskega orodja STARTER.
Keywords: asinhronski motor, optimizacija, regulacija, Siemens Sinamics G120C, Štore Steel
Published in DKUM: 01.07.2024; Views: 265; Downloads: 92
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7. Numerično določanje karakteristik sinhronskega motorja z različnimi velikostmi trajnih magnetov : magistrsko deloDavor Car, 2024, master's thesis Abstract: Magistrsko delo obravnava osnovni pristopa k modeliranju in konstruiranju sinhronskega motorja s trajnimi magneti s pomočjo računalniškega programa Flux. Izvedena je numerična analiza konstrukcijskih parametrov trajnih magnetov na navorno karakteristiko motorja. Analiza zajema vpliv različnih dimenzij in postavitev magnetov na vrednost valovitosti navora in razmerje navora proti volumnu trajnih magnetov. Rezultati nakazujejo, da je s predstavljenim računalniško podprtim pristopom, moči že v fazi načrtovanja motorja izbrati najustreznejše dimenzije za doseganje čim boljšega izkoristka z želeno navorno karakteristiko.
Keywords: Elektromotor, sinhronski stroj, sinhronski motor s trajnimi magneti, STSM, modeliranje, Flux, MKE, metoda končnih elementov, navitje, trajni magneti, valovitost navora, razmerje navora na volumen
Published in DKUM: 01.07.2024; Views: 136; Downloads: 54
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8. Design and optimization of a spherical magnetorheological actuatorJakob Vizjak, Anton Hamler, Marko Jesenik, 2023, original scientific article Abstract: Recently, an increasing number of electromagnetic devices have been using smart fluids. These include ferrofluids, electrorheological fluids, and magnetorheological (MR) fluids. In the paper, magnetorheological fluids are considered for use in a spherical actuator for haptic applications. An approach is presented to the design and optimization of such a device, using finite element method modelling linked with differential evolution (DE). Much consideration was given to the construction of the objective function to be minimized. A novel approach to objective function assembly was used, using reference values based on the model design and created with parameters set to the midpoint values of the selected range. It was found to be a useful strategy when the reference values are unknown. There were four parameters to be optimized. Three of them gravitated towards the boundary value, and the fourth (actuator radius) was somewhere in between. The value of the objective function reached a minimum in the range of actuator radius between 42.9880 mm and 45.0831 mm, which is about a 5% difference in regard to the actuator radius. Three passes of optimization were performed with similar results, proving the robustness of the algorithm.
Keywords: magnetorheological fluid, finite element method, FEM, optimization, differntial evolution, DE, actuator
Published in DKUM: 22.05.2024; Views: 173; Downloads: 22
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9. Innovative approach for the determination of a DC motor’s and drive’s parameters using evolutionary methods and different measured current and angular speed responsesMarko Jesenik, Miha Ravber, Mislav Trbušić, 2024, original scientific article Abstract: The determination is presented of seven parameters of a DC motor’s drive. The determination was based on a comparison between the measured and simulated current and speed responses. For the parameters’ determination, different evolutionary methods were used and compared to each other. The mathematical model presenting the DC drives model was written using two coupled differential equations, which were solved using the Runge–Kutta first-, second-, third- and fourth-order methods. The approach allows determining the parameters of controlled drives in such a way that the controller is taken into account with the measured voltage. Between the tested evolutionary methods, which were Differential Evolution with three strategies, Teaching-Learning Based Optimization and Artificial Bee Colony, the Differential Evolution (DE/rand/1/exp) can be suggested as the most appropriate for the presented problem. Measurements with different sampling times were used, and it was found out that at least some measuring points should be at the speed-up interval. Different lengths of the measured signal were tested, and it is sufficient to use a signal consisting of the drive’s acceleration and a short part of the stationary operation. The analysis showed that the procedure has good repeatability. The biggest deviation of calculated parameters considering 10 repeated measurements was 6% in case of the La calculation. The deviations of all the other parameters’ calculations were less than 2%.
Keywords: differential evolution, artificial bee colony, teaching-learning based optimization, DC motors, electric drive
Published in DKUM: 26.01.2024; Views: 230; Downloads: 26
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10. Sensitivity Analysis of Hybrid Powertrain Pre-calibration Algorithms : magistrsko deloSimon Šegula, 2023, master's thesis Abstract: Currently, meeting the new fuel consumption and emissions standards is the biggest challenge in the automotive industry. One of the solutions is hybridization of the vehicle’s powertrain. This brings with it larger complexity of the vehicle control unit and its pre-calibration. This thesis explores gear shift map and load point shift map, which are two pre-calibration maps included in the vehicle control unit. More specifically it delves in to how the pre-calibration maps are created and how changing their parameters impacts the fuel consumption of the vehicle. Algorithms and optimization simulations were created and performed using AVL’s tool called the Powertrain system optimizer (PSO) which was created within the MATLAB software.
Keywords: Hybrid electric vehicle, Hybrid powertrain, Gear shift map, Load point shift map, Pre-calibration.
Published in DKUM: 23.11.2023; Views: 393; Downloads: 0 |
