Thermal Analysis of Human Tissues Exposed to Focused Beam THz Radiations

The thermal response of human tissues exposed to a focused beam terahertz electromagnetic radiation is evaluated through a combined analytical electromagnetic wave solution and a step-by-step finite element numerical model, which solves Pennes’ bioheat equation. The computational procedure is applied to a three-layer model of the human tissues for wave frequencies ranging from 0.025 THz to 1 THz and compared with a more detailed five-layer model. The effects of the Gaussian beam parameters of the electromagnetic radiation on the temperature elevation are finally evaluated

Accuracy Assessment of Numerical Dosimetry for the Evaluation of Human Exposure to Electric Vehicle Inductive Charging Systems

In this article, we discuss numerical aspects related to the accuracy and the computational efficiency of numerical dosimetric simulations, performed in the context of human exposure to static inductive charging systems of electric vehicles. Two alternative numerical methods based on electric vector potential and electric scalar potential formulations, respectively, are here considered for the electric field computation in highly detailed anatomical human models. The results obtained by the numerical implementation of both approaches are discussed in terms of compliance assessment with ICNIRP guidelines limits for human exposure to electromagnetic fields. In particular, different strategies for smoothing localized unphysical outliers are compared, including novel techniques based on statistical considerations. The outlier removal is particularly relevant when comparison with basic restrictions is required to define the safety of electromagnetic fields exposure. The analysis demonstrates that it is not possible to derive general conclusions about the most robust method for dosimetric solutions. Nevertheless, the combined use of both formulations, together with the use of an algorithm for outliers removal based on a statistical approach, allows to determine final results to be compared with reference limits with a significant level of reliability

Safety Checkpoints

partially_open9sìopenKazemipour, Alireza; Kleine-Ostmann, Thomas; Schrader, Thorsten; Allal, Djamel; Charles, Michael; Zilberti, Luca; Borsero, Michele; Bottauscio, Oriano; Chiampi, MarioKazemipour, Alireza; Kleine Ostmann, Thomas; Schrader, Thorsten; Allal, Djamel; Charles, Michael; Zilberti, Luca; Borsero, Michele; Bottauscio, Oriano; Chiampi, Mari

Power losses in thick steel laminations with hysteresis

Magnetic power losses have been experimentally investigated and theoretically predicted over a range of frequencies (direct current—1.5 kHz) and peak inductions (0.5-1.5 T) in 1‐mm‐thick FeSi 2 wt. % laminations. The direct current hysteresis properties of the system are described by the Preisach model, with the Preisach distribution function reconstructed from the measurement of the recoil magnetization curve (Bp=1.7 T). On this basis, the time behavior of the magnetic induction vs frequency at different lamination depths is calculated by a finite element method numerical solution of Maxwell equations, which takes explicitly into account the Preisach model hysteretic B(H) relationship. The computed loop shapes are, in general, in good agreement with the measured ones. The power loss dependence on frequency is predicted and experimentally found to change from a ∼f3/2 to a ∼f2 law with increasing peak induction

A numerical survey of motion-induced electric fields experienced by MRI operators

This paper deals with the electric field generated inside the bodies of people moving in proximity to magnetic resonance scanners. Different types of scanners (tubular and open) and various kinds of movements (translation, rotation, and revolution) are analyzed, considering the homogeneous human model proposed in some technical Standards. The computations are performed through the Boundary Element Method, adopting a reference frame attached to the body, which significantly reduces the computational burden. The induced electric fields are evaluated in terms of both spatial distributions and local time evolutions. The possibility of limiting the study to the head without affecting the accuracy of the results is also investigated. Finally, a first attempt to quantify the transient effect of charge separation is proposed