The paper deals with an analytical assessment of a whole-body averaged specific absorption rate ( $SAR_{WB}$ ) when human body is illuminated by a short dipole antenna. The body is represented by a simple parallelepiped whose electric properties correspond to relative electric permittivity and electric conductivity of muscle tissue. The antenna-body distance and frequency are changed while the antenna parameters and body geometry are constant. In the computation of transmitted field into the body used for $SAR_{WB}$ calculation, the air-body interface is taken into account by means of transmission coefficient stemming from Modified Image Theory (MIT). First, the theoretical background is outlined and then the results depicting the behaviour of $SAR_{WB}$ with respect to antenna-body distance and frequency are presented. The resulting $SAR_{WB}$ values do not exceed the basic restriction nor for occupational nor for general population.
Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n = 2 RMP maintaining good confinement . Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes.
This paper presents a stochastic approach to the assessment of the temperature elevation in human head tissues due to the exposure to high frequency electromagnetic field. The novelty in this work is based on the coupling of the heterogeneous human head model with the stochastic method. Namely, the thermal parameters of three head tissues are modeled as random variables in order to capture the influence of the input uncertainty on the temperature elevation. The volumetric perfusion blood rate and tissue thermal conductivity of scalp, skull and brain are modelled as random variables with uniform distributions. The chosen thermal parameters are selected according to the findings in the previous work of the authors for a simpler homogeneous human brain model. The chosen parameters are shown to be the most influential ones regarding the temperature elevation. The propagation of uncertainties from the input random parameters to the output of interest, i.e. temperature elevation is carried out by using the non-intrusive Lagrange stochastic collocation method. A sparse grid interpolation in the multidimensional random space is used which speeds up the calculation compared to traditional Monte Carlo sampling methods or full tensor stochastic collocation approach. The presented results provide an insight into the behavior of the model output with respect to parameter variations and allows the ranking of the input parameters from the most to the least influential ones.
This paper investigates the differences in dipole current and input impedance due to different source models in the framework of boundary element formalism. The half-wavelength and full-wavelength dipole antennas are placed in free space and above a lossy medium. Antenna current and input impedance are obtained by numerically solving the Pocklington's integro-differential equation via Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM). Two different feeding structures are used as excitation sources, a delta gap source model usually used under GB-IBEM formalism and a magnetic frill source model. Different segment numbers are also used. The results indicate that the current magnitude in case of half-wavelength dipole antenna varies to a relatively great extent depending on the applied voltage generator model. Input impedance does not vary due to different source models, however, its value changes greatly with segment number.
The paper deals with the deterministic-stochastic model of the human body represented as cylindrical antenna illuminated by a low frequency electric field. Both analytical and numerical (Galerkin-Bubnov scheme of Boundary Element Method) deterministic solutions of the problem are outlined. This contribution introduces the new perspective of the problem: the variability inherent to input parameters, such as the height of the body, the shape of the body, and the conductivity of body tissue, is propagated to the output of interest (induced axial current). The stochastic approach is based on the stochastic collocation (SC) method. Computational examples show the mean trend of both analytically and numerically computed axial current with the confidence margins for different set of input random variables. The results point out the possibility of improving the efficiency in calculation of basic restriction parameter values in electromagnetic dosimetry.
This chapter first deals with derivation of continuity equation and Lorentz force, and a derivation of Maxwell's equations from the electromagnetic field is carried out. Finally, a variational basis of numerical solution methods in electromagnetics is discussed. The chapter deals with Hamilton's variational principle in mechanics, Newton's equation of motion, and Noether's theorem. There are physical quantities that do not change throughout the time development of physical systems. These quantities are stated to be conserved under certain conditions which are governed by conservation laws. The chapter exploits the approach that goes the other way around by exploiting the symmetry properties of the Lagrangian, similar to the approach presented in. It can be concluded that electric and magnetic fields are obtained from the equations of motion for charge particles and they are gauge invariant.
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