A numerical model of a human body with an intramedullary nail in the femur was built to evaluate the effects of the implant on the current density distribution in low frequency electric and magnetic fields. The intramedullary nail was chosen because it is one of the longest conductive implants used in medicine. The results show that the implant significantly increases the current density in locations where it is in contact with soft tissue. This implies that the existing safety limits do not necessarily protect implanted persons to the same extent as they protect people without implants.
COBISS.SI-ID: 25907161
We investigated occupational exposure to EMF of a multi-band base station antenna at 900, 1800, and 2100 MHz. Special attention was given to simultaneous exposure to several frequencies, their interaction and the additivity of resulting SAR. The 2100 MHz exposure results in highest spatial-peak SAR averaged over 10 g of tissue, while whole-body SAR is similar at all three frequencies. At distances above 200 mm from the antenna, whole-body SAR is a more limiting factor for compliance to exposure guidelines, while at shorter distances spatial-peak SAR is more limiting. For evaluation of combined exposure, a simple summation of spatial-peak SAR maxima at each frequency gives a good conservative estimate, but it was found to depend on the distribution of transmitting power between the different frequency bands.
COBISS.SI-ID: 8222804
Induction cookers use an intermediate frequency magnetic field to heat the cooking vessel. The magnetic flux density produced by an induction cooker during operation was measured according to the standards, and the measured values were below the limits set there. Measurements were used to validate a numerical model of a cooker consisting of three vertically displaced coaxial current loops at 35 kHz. The results show that the magnetic fields produced by induction cookers do not cause the basic restriction for the internal electric field to be exceeded in children or foetuses, even when the field is increased by a factor of 5, which can happen when the cookware is inappropriate and/or miss-aligned. The induced current density, however, is relatively close to its basic restriction and could potentially exceed it even for induction cookers in compliance with the currently valid standard (EN 62233).
COBISS.SI-ID: 8589652
Induction heating equipment is a source of strong and nonhomogeneous magnetic fields, which can exceed occupational reference levels. We investigated a case of an induction tempering tunnel furnace. Measurements of the emitted magnetic flux density (B) were performed during its operation and used to validate a numerical model of the furnace. This model was used to compute the values of B and the induced in situ electric field (E) for 15 different body positions relative to the source. For each body position, the computed B values were used to determine their maximum and average values, which were then compared to the ICNIRP reference level, and E values to the ICNIRP basic restriction. Our results show that in nonhomogeneous fields, the maximum B is an overly conservative predictor of overexposure, as it yields many false positives. The average B yielded fewer false positives, but as the number of averaging points increased, false negatives emerged. The most reliable averaging schemes were obtained for averaging over the torso with quadratic averaging, with no false negatives even for the maximum number of averaging points investigated.
COBISS.SI-ID: 9356372