1. Magnetic flux density measurement platform for an inductive wireless power transmitter coil designNataša Prosen, Miro Milanovič, Jure Domajnko, 2022, izvirni znanstveni članek Opis: This paper presents a platform developed for automated magnetic flux density measurement. The platform was designed to be used to measure the magnetic flux density of the
transmitter/receiver coil of an inductive wireless power transfer system. The magnetic flux density
of a transmitter was measured using a small, 3-axis search coil. The search coil was positioned in
the 3D space above the transmitter coil using a 3D positioning mechanism and used to measure
the magnetic flux density at a specific point. The data was then sent to a computer application to
visualize the magnetic flux density. The measured magnetic field could be used in combination with
electromagnetic field solvers to design and optimize transmitter coils for inductive wireless power
transfer systems.
Ključne besede: magnetic field, magnetic flux density, IPT, transmitter coil design, EM solver
Objavljeno v DKUM: 01.04.2025; Ogledov: 0; Prenosov: 7
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2. Contactless determination of a permanent magnet’s stable position within ferrofluidMislav Trbušić, Anton Hamler, Viktor Goričan, Marko Jesenik, 2022, izvirni znanstveni članek Opis: 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.
Ključne besede: permanent magnet, levitation, ferrofluid, magnetic sensor, magnetic field, finite element method, FEM
Objavljeno v DKUM: 28.03.2025; Ogledov: 0; Prenosov: 9
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3. Transforming and comparing data between standard SQUID and OPM-MEG systemsUrban Marhl, Anna Jodko-Wladzinska, Rüdiger Brühl, Tilmann Sander, Vojko Jazbinšek, 2022, izvirni znanstveni članek Opis: Optically pumped magnetometers (OPMs) have recently become so sensitive that they are suitable for use in magnetoencephalography (MEG). These sensors solve operational problems of the current standard MEG, where superconducting quantum interference device (SQUID) gradiometers and magnetometers are being used. The main advantage of OPMs is that they do not require cryogenics for cooling. Therefore, they can be placed closer to the scalp and are much easier to use. Here, we measured auditory evoked fields (AEFs) with both SQUID- and OPM-based MEG systems for a group of subjects to better understand the usage of a limited sensor count OPM-MEG. We present a theoretical framework that transforms the within subject data and equivalent simulation data from one MEG system to the other. This approach works on the principle of solving the inverse problem with one system, and then using the forward model to calculate the magnetic fields expected for the other system. For the source reconstruction, we used a minimum norm estimate (MNE) of the current distribution. Two different volume conductor models were compared: the homogeneous conducting sphere and the three-shell model of the head. The transformation results are characterized by a relative error and cross-correlation between the measured and the estimated magnetic field maps of the AEFs. The results for both models are encouraging. Since some commercial OPMs measure multiple components of the magnetic field simultaneously, we additionally analyzed the effect of tangential field components. Overall, our dual-axis OPM-MEG with 15 sensors yields similar information to a 62-channel SQUID-MEG with its field of view restricted to the right hemisphere.
Ključne besede: optically pumped magnetometer, magnetoencephalography, superconducting quantum interference device, magnetic field map
Objavljeno v DKUM: 26.06.2024; Ogledov: 153; Prenosov: 16
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4. Power line magnetic field deviations for three different definitions of current unbalanceDanka Antic, Anamarija Juhas, Miodrag Milutinov, 2019, strokovni članek Opis: An estimation procedure of the public's exposure to the low-frequency magnetic field generated by overhead power lines, according to the international standards, implies measurement and an extrapolation. It is necessary to measure both the magnetic field around the lines and the current in the lines simultaneously. The extrapolation procedure implies the calculation of the maximum magnetic field that will occur when the line current achieves its maximum. The calculation relies on a proportion between the current in the power line and the magnetic field around the power line, which is valid only when the currents are balanced. Unfortunately, the standards do not cover the unbalanced cases. The relation between the current unbalance and magnetic field could improve the estimation procedure. In the literature, several different definitions of the current unbalance could be found. In this paper, a comparison of three different definitions of current unbalance and their relation to the deviation of a magnetic field are considered. The magnetic field is calculated in the vicinity of the bus bar. The same procedure could also be applied around overhead power lines. The definitions for the current unbalance used in this paper are derived from the existing definitions of the voltage unbalance. Only one of these three definitions considers phase unbalance. The relationships between current unbalance and the maximum deviation of the magnetic field are found to be proportional.
Ključne besede: magnetic field, power delivery, measurement, public exposure assessment
Objavljeno v DKUM: 22.12.2023; Ogledov: 506; Prenosov: 143
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5. Electric and magnetic field measurements for high voltage transmission lines : the case of TurkeyMehmet Zeki Çelik, Mehmet Murat Ispirli, Yusuf Öner, Bülent Oral, 2019, strokovni članek Opis: A power system is a facility that creates low-frequency electromagnetic fields (EMF) with its highvoltage level and high electric current capacity. In this respect, these electromagnetic fields need to be significantly evaluated from the aspects of both those who are exposed to the fields due to the structure of the facility during their daily lives and those who are exposed to the fields due to their occupation. In this study, the transmission lines and substations in the power system of Turkey are evaluated on account of electric and magnetic field measurements. Firstly, the people living in general public zones near the transmission line or substation were examined. In another part of the study, measurements were made in the occupational exposure of the staff in the energy zone. The results obtained from measurements are compared with the limit values provided by the International Commission on Non%Ionizing Radiation Protection (ICNIRP). The measurements were performed by NARDA EFA-300 electromagnetic field measurement. The closest point to the ground was determined as the reference point for the measurements performed on transmission lines. The results for different distances were obtained by performing measurements following those reference points with fixed distances.
Ključne besede: electric field, ELF, electromagnetic filed, ICNIRP, magnetic field
Objavljeno v DKUM: 05.12.2023; Ogledov: 424; Prenosov: 7
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6. The properties of the material gadolinium and the working agent used in the installation of magnetic refrigeration devicesDorin Botoc, Jurij Avsec, Adrian Plesca, Georgel Gabor, Rusu Ionut, 2020, strokovni članek Opis: Much remains to be done to understand better and thus achieve better control over magnetic materials to maximize their magnetocaloric properties and performance, specifically for gadolinium. A clear path forward is highlighted by thorough experiments coupled with theory, in which the latter is tested and re%ned against the former, thus resulting in discoveries of new and improved materials and bringing near-room-temperature magnetic refrigeration technology to fruition in the near future.
Ključne besede: Gadolinium, heat transfer, magneto-calorific, magnetic field
Objavljeno v DKUM: 01.12.2023; Ogledov: 425; Prenosov: 321
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7. Assessment of human exposure to electric and magnetic fields near transmission lines using FEMMBojan Glushica, Blagoja Markovski, Andrijana Kuhar, Vesna Arnautovski Toseva, 2023, izvirni znanstveni članek Opis: The intensity of ELF electric and magnetic fields near transmission lines is of particular interest in environmental and equipment protection studies. The use of numerical tools is the most efficient method for their assessment. In this paper, we numerically compute the electric and magnetic fields near different configurations of high-voltage transmission lines using the open- source software FEMM 4.2. Computed fields are compared with reference levels related to human exposure to electromagnetic fields. The accuracy of the applied method is validated with published, numerically computed and measured results.
Ključne besede: finite elements method, transmission lines, electric field, magnetic field, electromagnetic computation
Objavljeno v DKUM: 11.10.2023; Ogledov: 525; Prenosov: 353
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8. Assessment of magnetic fluid losses out of magnetic properties measurementMiloš Beković, Irena Ban, Anton Hamler, 2010, objavljeni znanstveni prispevek na konferenci Opis: In this paper an improved measurement system for experimental assessment of magnetic fluid losses is presented. When fluid is exposed to AC magnetic field, three different losses mechanisms are active; relaxation, hysteresis and resonance mechanism. In this paper not individual contributions where studied but combine acting which can be determine as specific power losses (SPL). SPL of the sample is obtained for a variety of amplitudes and frequencies of magnetic field with presented method of measurement of field parameters where results revealed f H2 dependence for fixed temperature of the sample. Temperature dependence of SPL is examined with calorimetrical measurements, where heating of magnetic fluid at fixed value of applied field and various frequencies is examined and results revealed linearly decreasing temperature dependence.
Ključne besede: magnetic fluid loss, magentic field, hysteresis loop
Objavljeno v DKUM: 30.06.2017; Ogledov: 1465; Prenosov: 432
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9. Ecological alternatives to the reduction and oxidation processes in dyeing with vat and sulphur dyesMojca Božič, Vanja Kokol, 2008, pregledni znanstveni članek Opis: This article gives a summary of the most commonly used ecologically unfriendly processes for the reduction and oxidation of vat and sulphur dyes. It also describes the new alternatives that are in the development stage and could be important in the near future. Sodium dithionite as the dominant reducing agent produces large amounts of sodium sulphate, and also toxic sulphite and thiosulphate as by-products. Consequently, high amounts of hydrogen peroxide and alkali are required for the treatment of effluents, which add to the cost of the process. Attempts have been made to use organic biodegradable reducing agents, enzymes, catalytic hydrogenation, and also indirect or direct, electrochemical reductive methods that employ a redox mediator (electron-carrier). The reduction has also been carried out via the dye radical molecule or, in the case of indigo, by direct electrochemical reduction using graphite as the electrode material. Physical techniques, for example using ultrasound, magnetic fields or UV have been shown to be effective only when used to accelerate methods using classical reduction and oxidation processes. However, although these methods offer some environmental benefits, there is still no satisfactory alternative reducing and/or oxidising agent available today.
Ključne besede: textile dyeing, vat dyes, sulphur dyes, reduction, oxidation, catalysis, ecology, organic agents, electrochemistry, ultrasound, magnetic field, UV application, biotechnology
Objavljeno v DKUM: 01.06.2012; Ogledov: 3143; Prenosov: 124
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