1,721,206 research outputs found
Ear temperature increase produced by cellular phones under extreme exposure conditions
No full textThis paper deals with the numerical prediction of temperature increase in the inner ear of subjects exposed to the electromagnetic (EM) radiation of conventional cellular phones. Attention has focused on the geometrical model of the internal ear organs and on including the intrinsic heating of the phone in the numerical thermal analysis. To this aim, infrared (IR) thermographic data have been used as time-variant Dirichlet boundary conditions (BCs) on the touching ear-phone boundary, while new convective BCs are applied on the cells not in contact. Numerical results, obtained by a finite difference (FD) procedure, showed a maximum temperature increase of about 4 °C on the external ear, although significant thermal elevations were not observed in the most sensitive internal organs. These temperature rises are obtained under extreme exposure conditions, i.e., when forcing the phone at the maximum power of 250 mW for 30 min. © 2012 IEEE
Special Issue: Advances in Computational Electromagnetics
Full text linkRecent advances in computational electromagnetics (CEMs) have made the full characterization of complex magnetic materials possible, such as superconducting materials, composite or nanomaterials, rare-earth free permanent magnets, etc [...
Comparison of Transcranial Magnetic Stimulation Dosimetry between Structured and Unstructured Grids Using Different Solvers
Full text linkIn recent years, the interest in transcranial magnetic stimulation (TMS) has surged, necessitating deeper understanding, development, and use of low-frequency (LF) numerical dosimetry for TMS studies. While various ad hoc dosimetric models exist, commercial software tools like SimNIBS v4.0 and Sim4Life v7.2.4 are preferred for their user-friendliness and versatility. SimNIBS utilizes unstructured tetrahedral mesh models, while Sim4Life employs voxel-based models on a structured grid, both evaluating induced electric fields using the finite element method (FEM) with different numerical solvers. Past studies primarily focused on uniform exposures and voxelized models, lacking realism. Our study compares these LF solvers across simplified and realistic anatomical models to assess their accuracy in evaluating induced electric fields. We examined three scenarios: a single-shell sphere, a sphere with an orthogonal slab, and a MRI-derived head model. The comparison revealed small discrepancies in induced electric fields, mainly in regions of low field intensity. Overall, the differences were contained (below 2% for spherical models and below 12% for the head model), showcasing the potential of computational tools in advancing exposure assessment required for TMS protocols in different bio-medical applications
Chassis influence on the exposure assessment of a compact ev during wpt recharging operations
Full text linkIn this study, the external magnetic field emitted by a wireless power transfer (WPT) system and the internal electric field induced in human body models during recharging operations of a compact electric vehicle (EV) are evaluated. The magneticfield is calculated with a hybrid scheme coupling the boundary element method with the surface impedance boundary conditions in order to fit the multiscale open-boundary characteristics of the problem. A commercial software is then used to perform numerical dosimetry. Specifically, two realistic anatomical models, both in a driving position and in a standing posture, are considered, and the chassis of the EV is modeled either as a currently employed aluminum alloy and as a futuristic carbon fiber composite panel. Aligned and misaligned coil configurations of the WPT system are considered as well. The analysis of the obtained results shows that the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels are exceeded in the driving position, especially for the carbon fiber chassis, whereas the system is compliant with the basic restrictions, at least for the considered scenarios
Influence of posture and coil position on the safety of a WPT system while recharging a compact EV
Full text linkIn this study, the human exposure to the magnetic field emitted by a wireless power transfer (WPT) system during the static recharging operations of a compact electric vehicle (EV) is evaluated. Specifically, the influence of the posture of realistic anatomical models, both in standing and lying positions, either inside or outside the EV, is considered. Aligned and misaligned coil configurations of the WPT system placed both in the rear and front position of the car floor are considered as well. Compliance with safety standards and guidelines has proven that reference levels are exceeded in the extreme case of a person lying on the floor with a hand close to the WPT coils, whereas the system is always compliant with the basic restrictions, at least for the considered scenarios
Driving Range of Electric Vehicles Charged by Wireless Power Transfer
No full textElectric vehicles (EVs) are limited by the on-board batteries in terms of driving range and charging duration. In this paper, the driving range of electric vehicles (EVs) charged by wireless power transfer (WPT) systems is investigated. Specifically, a force-based vehicle model is coupled with a simple extended battery model to simulate the impact of wireless charging on the state of charge of the accumulator sub-system. In total, three different scenarios, i.e., urban, highway and combined driving are presented. The trade-off between having a standalone charging option versus combined dynamic and quasi-dynamic wireless charging is outlined and minimum system requirements, such as charging power levels and road coverage, for unlimited range are established. Furthermore, the effect of external factors such as ambient temperature, battery age and wireless transfer efficiency is investigated. It is shown that employing combined charging at medium power levels is sufficient to achieve unlimited range compared to high power requirements for standalone charging. Finally, safety concerns regarding human exposure are addressed with lower charging powers
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