Assessment of Transmitted Power Density in the Planar Multilayer Tissue Model due to Radiation from Dipole Antenna

Recent relevant safety guidelines IEEE-Std C95.1- 2019 and ICNIRP-RF Guidelines 2020 have converged towards 6 GHz as a transition frequency from specific absorption rate (SAR), as basic restriction quantity, to absorbed power density (APD). Namely, the penetration of electromagnetic waves into the human tissue rapidly decreases as frequency increases, therefore, tissue heating can be considered as superficial above 6 GHz. However, besides the APD, an alternative internal dosimetric quantity transmitted power density or TPD is sometimes computed since its relation to SAR is more obvious and is easier to obtain. This paper deals with an analytical/numerical approach to determine TPD in planar multi-layered model of the human tissue exposed to the dipole antenna radiation. Analytical approach deals with assumed sinusoidal current distribution, while numerical approach pertains to the determination of current by solving the corresponding Pocklington integro-differential equation via Galerkin-Bubnov Indirect Boundary Element Method. The novelty presented in this paper with respect to previous work is a multilayer geometry whose effects are considered via the corresponding Fresnel plane wave reflection/transmission approximation. Some illustrative results for current distribution, transmitted field, volume power density (VPD) and TPD at various frequencies and distances of the antenna from the interface are given

EUROfusion Integrated Modelling (EU-IM) capabilities and selected physics applications

International audienceRecent developments and achievements of the EUROfusion Code Development for Integrated Modelling project (WPCD), which aim is to provide a validated integrated modelling suite for the simulation and prediction of complete plasma discharges in any tokamak, are presented. WPCD develops generic complex integrated simulations, workflows, for physics applications, using the standardized European Integrated Modelling (EU-IM) framework. Selected physics applications of EU-IM workflows are illustrated in this paper

Primjena metode stohastičke kolokacije i analize osjetljivosti na modele u biolektromagnetizmu

The thesis includes four contributed journal papers each providing an example of an efficient application of Stochastic Collocation Method (SCM) to models in bioelectromagnetism. Examples from the first two papers feature the coupling of SCM and Galerkin-Bubnov Indirect Boundary Element Method for canonical geometry of the human body. The body is represented by cylindrical antenna whose geometry parameters and electric conductivity are random variables (RV) while the output of interest is the induced electric current/field. The first example features the low frequency exposure scenario, while the second one deals with the transient exposures. The 3rd research journal paper presents stochastic dosimetry of anatomically realistic head model consisting of skin, skull and brain tissues whose permittivity and conductivity are chosen to be RVs. The output of interest is induced electric field and the SCM is coupled with the Hybrid Finite Element/Boundary Element method. In the 4th research paper SC method is combined with the boundary element method (BEM) for stochastic analysis of scalar electric potential generated in the human brain in the process of transcranial electric stimulation with brain, skin and skull conductivities modelled as RVs. In these papers SCM is used to compute stochastic moments and confidence intervals which give information about the dispersion of the expected output. Additionally, ANalysis Of VAriance (ANOVA) concept is used for sensitivity analysis to estimate the impact of the input parameter variability on total output variance. The 5th paper included in the thesis is a review paper that outlines some examples of SC applied to other areas of computational electromagnetics (CEM) by the author and her co-workers.Ova teza sastoji se od četiri istraživačka rada od kojih svaki donosi primjer uspješne primjene metode stohastičke kolokacije na modele u bioelektromagnetizmu. U primjerima iz prva dva rada metoda stohastičke kolokacije spregnuta je s Galerkin-Bubnovljevom inačicom metode rubnih elemenata na primjeru kanonskog modela ljudskog tijela. Tijelo je modelirano kao cilindrična antenna čija su vodljivost i geometrijski parametri slučajne varijable, a izlazna veličina je inducirana struja/polje. U prvom primjeru tijelo je izloženo polju niske frekvencije, dok se u drugom primjeru radi o izloženosti tranzijentnom polju. U trećem istraživačkom radu stohastička kolokacija spregnuta je s hibridnom metodom konačnih/ rubnih elemenata i to za anatomski realističnu ljudsku glavu. Glava je sastavljena od tkiva kože, lubanje i mozga čije su električne permitivnosti i vodljivosti slučajne varijable, a veličina od interesa je inducirano električno polje. U četvrtom istraživačkom radu troslojni model glave korišten je za simulaciju transkranijalne električne stimulacije mozga. Vodljivosti lubanje, kože i mozga modelirane su kao slučajne varijable, a kombinacija stohastičke kolokacije i metode rubnih elemenata korištena je za proračun stohastičkog odziva skalarnog električnog potencijala. U ovim radovima primjenom metode stohastičke kolokacije izračunati su stohastički momenti i intervali pouzdanosti izlaznih veličina od interesa u svrhu određivanja njihovog raspona. Uz to, obavljena je i analiza osjetljivosti prema principu analize varijance ANOVA kako bi se uspostavio odnos varijacije ulaznih parametara i totalne varijance izlaza. Peti rad naveden u ovoj tezi preglednog je karaktera te donosi primjere primjene stohastičke kolokacije na druga područja računalnog elektromagnetizma, također od strane autorice i njenih kolega

Primjena metode stohastičke kolokacije i analize osjetljivosti na modele u biolektromagnetizmu

The thesis includes four contributed journal papers each providing an example of an efficient application of Stochastic Collocation Method (SCM) to models in bioelectromagnetism. Examples from the first two papers feature the coupling of SCM and Galerkin-Bubnov Indirect Boundary Element Method for canonical geometry of the human body. The body is represented by cylindrical antenna whose geometry parameters and electric conductivity are random variables (RV) while the output of interest is the induced electric current/field. The first example features the low frequency exposure scenario, while the second one deals with the transient exposures. The 3rd research journal paper presents stochastic dosimetry of anatomically realistic head model consisting of skin, skull and brain tissues whose permittivity and conductivity are chosen to be RVs. The output of interest is induced electric field and the SCM is coupled with the Hybrid Finite Element/Boundary Element method. In the 4th research paper SC method is combined with the boundary element method (BEM) for stochastic analysis of scalar electric potential generated in the human brain in the process of transcranial electric stimulation with brain, skin and skull conductivities modelled as RVs. In these papers SCM is used to compute stochastic moments and confidence intervals which give information about the dispersion of the expected output. Additionally, ANalysis Of VAriance (ANOVA) concept is used for sensitivity analysis to estimate the impact of the input parameter variability on total output variance. The 5th paper included in the thesis is a review paper that outlines some examples of SC applied to other areas of computational electromagnetics (CEM) by the author and her co-workers.Ova teza sastoji se od četiri istraživačka rada od kojih svaki donosi primjer uspješne primjene metode stohastičke kolokacije na modele u bioelektromagnetizmu. U primjerima iz prva dva rada metoda stohastičke kolokacije spregnuta je s Galerkin-Bubnovljevom inačicom metode rubnih elemenata na primjeru kanonskog modela ljudskog tijela. Tijelo je modelirano kao cilindrična antenna čija su vodljivost i geometrijski parametri slučajne varijable, a izlazna veličina je inducirana struja/polje. U prvom primjeru tijelo je izloženo polju niske frekvencije, dok se u drugom primjeru radi o izloženosti tranzijentnom polju. U trećem istraživačkom radu stohastička kolokacija spregnuta je s hibridnom metodom konačnih/ rubnih elemenata i to za anatomski realističnu ljudsku glavu. Glava je sastavljena od tkiva kože, lubanje i mozga čije su električne permitivnosti i vodljivosti slučajne varijable, a veličina od interesa je inducirano električno polje. U četvrtom istraživačkom radu troslojni model glave korišten je za simulaciju transkranijalne električne stimulacije mozga. Vodljivosti lubanje, kože i mozga modelirane su kao slučajne varijable, a kombinacija stohastičke kolokacije i metode rubnih elemenata korištena je za proračun stohastičkog odziva skalarnog električnog potencijala. U ovim radovima primjenom metode stohastičke kolokacije izračunati su stohastički momenti i intervali pouzdanosti izlaznih veličina od interesa u svrhu određivanja njihovog raspona. Uz to, obavljena je i analiza osjetljivosti prema principu analize varijance ANOVA kako bi se uspostavio odnos varijacije ulaznih parametara i totalne varijance izlaza. Peti rad naveden u ovoj tezi preglednog je karaktera te donosi primjere primjene stohastičke kolokacije na druga područja računalnog elektromagnetizma, također od strane autorice i njenih kolega

An Efficient Deterministic-Stochastic Model of the Human Body Exposed to ELF Electric Field

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

Sensitivity analysis of the direct time domain analytical solution for transient impedance of the horizontal grounding electrode using ANOVA approach

International audienc

Stochastic-deterministic and sensitivity analysis of the transient field generated by GPR dipole antenna and transmitted into a lossy ground

International audienc

Advanced analysis of the transient impedance of the horizontal grounding electrode: From statistics to sensitivity indices

International audienc

Stochastic Collocation Applications in Computational Electromagnetics

The paper reviews the application of deterministic-stochastic models in some areas of computational electromagnetics. Namely, in certain problems there is an uncertainty in the input data set as some properties of a system are partly or entirely unknown. Thus, a simple stochastic collocation (SC) method is used to determine relevant statistics about given responses. The SC approach also provides the assessment of related confidence intervals in the set of calculated numerical results. The expansion of statistical output in terms of mean and variance over a polynomial basis, via SC method, is shown to be robust and efficient approach providing a satisfactory convergence rate. This review paper provides certain computational examples from the previous work by the authors illustrating successful application of SC technique in the areas of ground penetrating radar (GPR), human exposure to electromagnetic fields, and buried lines and grounding systems