Oriano Bottauscio | INRIM - Academia.edu (original) (raw)

Papers by Oriano Bottauscio

Research paper thumbnail of Contactless Electromagnetic Temperature Sensors for Spinning Devices

IEEE Transactions on Magnetics, 2000

Contactless electromagnetic temperature sensors are analyzed and compared, under a number of conf... more Contactless electromagnetic temperature sensors are analyzed and compared, under a number of configurations, for applications in spinning devices. Their working principle is based on the variation of electrical or magnetic properties with temperature. By a preliminary study, carried out through finite element modeling, a number of effective solutions have been identified and a few of them have then been selected for testing in the laboratory. Two significant experimental examples are here discussed.

Research paper thumbnail of Soft Magnets for Passive Attitude Stabilization of Small Satellites

IEEE Transactions on Magnetics, 2010

The spinning and oscillatory motions of small orbiting satellites can be damped exploiting the ma... more The spinning and oscillatory motions of small orbiting satellites can be damped exploiting the magnetic energy dissipation occurring in onboard soft magnetic strips, cyclically excited by the oscillation of the earth field component along their axis. In this paper we investigate the role played by the intrinsic magnetic properties of the material, the aspect ratio of the strips, and their mutual arrangement in achieving maximum energy dissipation under typical spacecraft working conditions. Grain-oriented Fe-Si, mumetal, and Fe-based amorphous alloys, all endowed with near-rectangular hysteresis loops, are considered. Their energy loss behaviour is calculated when, either as single strip samples or arranged into an array of strips, they are subjected to a slowly oscillating magnetic field of defined peak value, emulating the action of the earth magnetic field on the travelling satellite. The strip size and array layout leading to maximum energy loss are predicted. Amorphous alloys, combining high saturation magnetization with flexible hysteresis loop properties, are shown to lead to the best damping behaviour under both oscillating and spinning satellite motions. In the latter case the Fe-Si strips appear to provide comparably high damping effects, while inferior behaviour is always predicted with mumetal samples.

Research paper thumbnail of Modeling High-Frequency Magnetic Losses in Transverse Anisotropy Amorphous Ribbons

IEEE Transactions on Magnetics, 2015

The superior high-frequency magnetic behavior of transverse anisotropy amorphous ribbons can be q... more The superior high-frequency magnetic behavior of transverse anisotropy amorphous ribbons can be qualitatively interpreted in terms of rotation dominated magnetization process and quantitatively predicted describing the spin dynamics by the Landau-Lifshitz-Gilbert (LLG) equation in association with the electromagnetic diffusion equation. The theory is applied to comprehensive measurements performed on Co-based alloys, tested as field-annealed tapewound rings from dc to 1 GHz with combination of fluxmetric and transmission line methods. The LLG equation is numerically solved considering the role of magnetostatic, exchange, anisotropy, eddy current, and applied fields. It accurately describes the high-frequency energy losses, ensuing from eddy currents, and spin damping. By further considering the low-frequency domain wall contribution, a full scenario for the broadband losses is achieved.

Research paper thumbnail of A Multiscale Approach to Predict Classical<newline/> Losses in Soft Magnetic Composites

IEEE Transactions on Magnetics, 2000

This paper presents the application of a finite element multiscale method, based on the homogeniz... more This paper presents the application of a finite element multiscale method, based on the homogenization technique, to the prediction of classical losses in soft magnetic composite materials. The experimental results, obtained for a wide range of frequencies and for various toroidal samples with different cross sections, are explained by using the considered model. It has been found that the classical losses are influenced by the dimensions of the sample, as well as by the conductivity and the length of the random contacts between the grains.

Research paper thumbnail of An Experimental-Computational Technique for Evaluating Magnetic Field Distributions Around Unknown Sources

IEEE Transactions on Magnetics, 2000

ABSTRACT This paper proposes a hybrid experimental-numerical technique, based on the boundary ele... more ABSTRACT This paper proposes a hybrid experimental-numerical technique, based on the boundary element method, able to reconstruct the magnetic field distribution in the free space outside the unknown field sources, without requiring the onerous process of source identification. The approach is validated by comparison with experimental data considering a Helmholtz coil system, where the connections of the coils and the supply currents can be controlled to generate different spatial distributions of the magnetic field. The presence of materials with high magnetic permeability, also involving eddy currents, is considered as well. An analysis on the reachable accuracy and on the related parameters is developed, with the final aim of obtaining a satisfactory compromise between result accuracy and experimental burden. Finally, the field values reconstructed by the proposed experimental-numerical technique are compared with the measured ones, showing a good agreement.

Research paper thumbnail of A GPU Computational Code for Eddy-Current Problems in Voxel-Based Anatomy

IEEE Transactions on Magnetics, 2015

ABSTRACT A hybrid finite element–boundary element method, developed to solve eddy-current problem... more ABSTRACT A hybrid finite element–boundary element method, developed to solve eddy-current problems in the frequency domain, is applied to the electromagnetic analysis of voxel-based human models. A specific procedure employs a massively parallelized algorithm implemented on a multiple Graphic Processing Units (GPU) code to speed up the solution of large systems whose matrix exceeds the RAM capability. The database structure used for the electromagnetic problem is also suitable for a successive thermal analysis to evaluate the distribution of the temperature elevation due to the energy deposited by the waves in the tissues. Finally, some examples of application are presented.

Research paper thumbnail of Thermal Analysis of Human Tissues Exposed to Focused Beam THz Radiations

IEEE Transactions on Magnetics, 2015

ABSTRACT The thermal response of human tissues exposed to a focused beam terahertz electromagneti... more ABSTRACT 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.

Research paper thumbnail of Effect of Tissue Parameters on Skin Heating Due to Millimeter EM Waves

IEEE Transactions on Magnetics, 2015

ABSTRACT This paper investigates the influence of electrical and thermal human tissue parameters ... more ABSTRACT This paper investigates the influence of electrical and thermal human tissue parameters on the heating of a body illuminated by a millimeter plane electromagnetic wave. A stochastic approach is considered with a three-layer model of the body: it is found that the parameters of skin play a major role.

Research paper thumbnail of On the use of TEM cells for the calibration of power frequency electric field meters

Measurement, 2010

ABSTRACT This paper focuses on the performances of TEM cells when used in the calibration of powe... more ABSTRACT This paper focuses on the performances of TEM cells when used in the calibration of power frequency environmental electric field meters. The spatial non-uniformity of the electric field inside a TEM cell is analyzed through experimental investigations and three-dimensional Boundary Element modeling to evaluate the field experienced by the sensing elements of actual 3D meter probes. The perturbation caused by the probe support is also taken into account. The uncertainty component associated with the spatial non-uniformity in the volume taken up by typical power and low frequency field probes is estimated. The field non-uniformity is also evaluated in relation to the use of TEM cells of reduced size. Finally, the field non-uniformity is exploited to predict the performance of an actual field meter operating in significant field gradients.

Research paper thumbnail of Evaluation of Electromagnetic Phenomena Induced by Transcranial Magnetic Stimulation

IEEE Transactions on Magnetics, 2000

ABSTRACT The electric current densities induced inside a human head by transcranial magnetic stim... more ABSTRACT The electric current densities induced inside a human head by transcranial magnetic stimulations are evaluated through a hybrid finite-element–boundary-element method applied to an anatomical model based on voxel data set. The results of the computational procedure are first validated considering two model problems. Then, the induced E-field within the head of Duke model of the Virtual Family are simulated for two different transcranial magnetic stimulation coils, evaluating the impact of tissue properties variability and model resolution.

Research paper thumbnail of A boundary element estimate of radiated emissions produced by unknown sources

International Symposium on Electromagnetic Compatibility - EMC EUROPE, 2012

ABSTRACT The paper presents a Boundary Element procedure able to predict the emission radiated by... more ABSTRACT The paper presents a Boundary Element procedure able to predict the emission radiated by unknown sources, starting from the knowledge of the electromagnetic field in a limited number of points placed on a surface surrounding the sources. The proposed approach is tested by analyzing the field distribution obtained as a superposition of the emissions produced by four different radiating elements. The influence of the number of points on the accuracy and the possibility of simplifying the measurement procedure are finally investigated.

Research paper thumbnail of Valutazione di emissioni elettromagnetiche prodotte da impianti in alta tensione continua

Research paper thumbnail of Uncertainty Estimate Associated With the Electric Field Induced Inside Human Bodies by Unknown LF Sources

IEEE Transactions on Instrumentation and Measurement, 2000

ABSTRACT This paper is focused on the uncertainty estimate of a hybrid experimental-numerical pro... more ABSTRACT This paper is focused on the uncertainty estimate of a hybrid experimental-numerical procedure for the evaluation of the electric field induced in a human model radiated by a low-frequency magnetic field produced by unknown sources. The procedure is based on magnetic field measurements in a limited number of points around the field source and makes use of the boundary element method. The uncertainty contribution due to the measurement operations is taken into account by evaluating its propagation through the computational process using a Monte Carlo approach coupled to a discrete numerical technique. The procedure is then applied to the case of a body exposed to the field generated by a Helmholtz coil system. The results show that the relative standard uncertainty of the estimated induced electric field is within a few percent.

Research paper thumbnail of Massively Parallelized Boundary Element Simulation of Voxel-Based Human Models Exposed to MRI Fields

IEEE Transactions on Magnetics, 2000

ABSTRACT Boundary element and hybrid boundary element—finite element approaches are applied to th... more ABSTRACT Boundary element and hybrid boundary element—finite element approaches are applied to the computation of induced electric field and specific absorption rate in voxel-based human models undergoing magnetic resonance imaging. Due to the very large size of the algebraic system, the procedure uses an iterative GMRES solver recalculating the element matrix at each iteration. A suitable processing of the Green integrals and a massively parallelized algorithm, based on the use of graphical processing units, leads to a strong reduction of the computational time.

Research paper thumbnail of Metrology to support therapeutic and diagnostic techniques based on electromagnetics and nanomagnetics

Rendiconti Lincei, 2015

ABSTRACT This paper presents an overview of the recent research activities carried on at INRIM in... more ABSTRACT This paper presents an overview of the recent research activities carried on at INRIM in the field of metrology for healthcare, aiming at supporting therapeutic and diagnostic techniques based on electromagnetics and nanomagnetics. Attention is here specifically focused on three research topics, respectively related to electromagnetic dosimetry for MR-safety, production and characterization of magnetic Ni80Fe20 nanodisks for biomedical applications and development of modeling tools to support the design of novel biosensors.

Research paper thumbnail of Motion-Induced Fields in Magnetic Resonance Imaging: Are the Dielectric Currents Really Negligible?

IEEE Magnetics Letters, 2015

ABSTRACT This paper deals with the exposure of humans moving through the stray stationary magneti... more ABSTRACT This paper deals with the exposure of humans moving through the stray stationary magnetic field produced by magnetic resonance imaging scanners. In particular, the work evaluates the influence of the dielectric currents, whose effects have been disregarded up to now, despite the very high permittivity values obtained by extrapolation based on the most common dispersion models of tissue properties. The analysis is carried out by considering a high-resolution anatomical model through an original numerical procedure that includes the dielectric phenomena. The results prove that the high values of the dielectric permittivity produce limited, but nonnegligible variations on the induced current density, while weakly influencing the electric field. Finally, the stability of the results with respect to variations of the dielectric permittivity practically removes the need for an accurate measurement of such a parameter that is affected by high uncertainties at very low frequencies.

Research paper thumbnail of Solution of Large Complex BEM Systems Derived From High-Resolution Human Models

IEEE Transactions on Magnetics, 2000

ABSTRACT The aim of this paper is the investigation of the numerical properties of the boundary e... more ABSTRACT The aim of this paper is the investigation of the numerical properties of the boundary element method (BEM) when applied to dosimetric analysis of human exposure to electromagnetic fields adopting high resolution voxel-based data sets. Some test problems are analyzed considering the neck region of the human body radiated by a loop antenna. Different strategies in the development of the problem equations are proposed and their effects on the conditioning of the BEM matrix are discussed. Several direct and iterative solvers are applied to the model problems and their efficiency is compared.

Research paper thumbnail of Collateral Thermal Effect of MRI-LINAC Gradient Coils on Metallic Hip Prostheses

IEEE Transactions on Magnetics, 2014

ABSTRACT This paper aims at evaluating the thermal effects produced by the gradient coils on pati... more ABSTRACT This paper aims at evaluating the thermal effects produced by the gradient coils on patients carrying metallic hip prostheses when undergoing check-up in combined magnetic resonance imaging with a linear accelerator systems. The computations are performed by two noncommercial codes specifically developed by the authors for voxel based human models. The electromagnetic field problem is solved by a hybrid finite element-boundary element technique implemented in a massively parallelized GPU system. The temperature elevation due to the electromagnetic exposure is then evaluated through a finite element code. The computations are performed for a large number of situations, considering both radial and axial arrangements of the patient.

Research paper thumbnail of A model to relate SAR to surface field measurements in human phantoms

Research paper thumbnail of A Potential-based Formulation for Motion-Induced Electric Fields in MRI

IEEE Transactions on Magnetics, 2015

Research paper thumbnail of Contactless Electromagnetic Temperature Sensors for Spinning Devices

IEEE Transactions on Magnetics, 2000

Contactless electromagnetic temperature sensors are analyzed and compared, under a number of conf... more Contactless electromagnetic temperature sensors are analyzed and compared, under a number of configurations, for applications in spinning devices. Their working principle is based on the variation of electrical or magnetic properties with temperature. By a preliminary study, carried out through finite element modeling, a number of effective solutions have been identified and a few of them have then been selected for testing in the laboratory. Two significant experimental examples are here discussed.

Research paper thumbnail of Soft Magnets for Passive Attitude Stabilization of Small Satellites

IEEE Transactions on Magnetics, 2010

The spinning and oscillatory motions of small orbiting satellites can be damped exploiting the ma... more The spinning and oscillatory motions of small orbiting satellites can be damped exploiting the magnetic energy dissipation occurring in onboard soft magnetic strips, cyclically excited by the oscillation of the earth field component along their axis. In this paper we investigate the role played by the intrinsic magnetic properties of the material, the aspect ratio of the strips, and their mutual arrangement in achieving maximum energy dissipation under typical spacecraft working conditions. Grain-oriented Fe-Si, mumetal, and Fe-based amorphous alloys, all endowed with near-rectangular hysteresis loops, are considered. Their energy loss behaviour is calculated when, either as single strip samples or arranged into an array of strips, they are subjected to a slowly oscillating magnetic field of defined peak value, emulating the action of the earth magnetic field on the travelling satellite. The strip size and array layout leading to maximum energy loss are predicted. Amorphous alloys, combining high saturation magnetization with flexible hysteresis loop properties, are shown to lead to the best damping behaviour under both oscillating and spinning satellite motions. In the latter case the Fe-Si strips appear to provide comparably high damping effects, while inferior behaviour is always predicted with mumetal samples.

Research paper thumbnail of Modeling High-Frequency Magnetic Losses in Transverse Anisotropy Amorphous Ribbons

IEEE Transactions on Magnetics, 2015

The superior high-frequency magnetic behavior of transverse anisotropy amorphous ribbons can be q... more The superior high-frequency magnetic behavior of transverse anisotropy amorphous ribbons can be qualitatively interpreted in terms of rotation dominated magnetization process and quantitatively predicted describing the spin dynamics by the Landau-Lifshitz-Gilbert (LLG) equation in association with the electromagnetic diffusion equation. The theory is applied to comprehensive measurements performed on Co-based alloys, tested as field-annealed tapewound rings from dc to 1 GHz with combination of fluxmetric and transmission line methods. The LLG equation is numerically solved considering the role of magnetostatic, exchange, anisotropy, eddy current, and applied fields. It accurately describes the high-frequency energy losses, ensuing from eddy currents, and spin damping. By further considering the low-frequency domain wall contribution, a full scenario for the broadband losses is achieved.

Research paper thumbnail of A Multiscale Approach to Predict Classical<newline/> Losses in Soft Magnetic Composites

IEEE Transactions on Magnetics, 2000

This paper presents the application of a finite element multiscale method, based on the homogeniz... more This paper presents the application of a finite element multiscale method, based on the homogenization technique, to the prediction of classical losses in soft magnetic composite materials. The experimental results, obtained for a wide range of frequencies and for various toroidal samples with different cross sections, are explained by using the considered model. It has been found that the classical losses are influenced by the dimensions of the sample, as well as by the conductivity and the length of the random contacts between the grains.

Research paper thumbnail of An Experimental-Computational Technique for Evaluating Magnetic Field Distributions Around Unknown Sources

IEEE Transactions on Magnetics, 2000

ABSTRACT This paper proposes a hybrid experimental-numerical technique, based on the boundary ele... more ABSTRACT This paper proposes a hybrid experimental-numerical technique, based on the boundary element method, able to reconstruct the magnetic field distribution in the free space outside the unknown field sources, without requiring the onerous process of source identification. The approach is validated by comparison with experimental data considering a Helmholtz coil system, where the connections of the coils and the supply currents can be controlled to generate different spatial distributions of the magnetic field. The presence of materials with high magnetic permeability, also involving eddy currents, is considered as well. An analysis on the reachable accuracy and on the related parameters is developed, with the final aim of obtaining a satisfactory compromise between result accuracy and experimental burden. Finally, the field values reconstructed by the proposed experimental-numerical technique are compared with the measured ones, showing a good agreement.

Research paper thumbnail of A GPU Computational Code for Eddy-Current Problems in Voxel-Based Anatomy

IEEE Transactions on Magnetics, 2015

ABSTRACT A hybrid finite element–boundary element method, developed to solve eddy-current problem... more ABSTRACT A hybrid finite element–boundary element method, developed to solve eddy-current problems in the frequency domain, is applied to the electromagnetic analysis of voxel-based human models. A specific procedure employs a massively parallelized algorithm implemented on a multiple Graphic Processing Units (GPU) code to speed up the solution of large systems whose matrix exceeds the RAM capability. The database structure used for the electromagnetic problem is also suitable for a successive thermal analysis to evaluate the distribution of the temperature elevation due to the energy deposited by the waves in the tissues. Finally, some examples of application are presented.

Research paper thumbnail of Thermal Analysis of Human Tissues Exposed to Focused Beam THz Radiations

IEEE Transactions on Magnetics, 2015

ABSTRACT The thermal response of human tissues exposed to a focused beam terahertz electromagneti... more ABSTRACT 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.

Research paper thumbnail of Effect of Tissue Parameters on Skin Heating Due to Millimeter EM Waves

IEEE Transactions on Magnetics, 2015

ABSTRACT This paper investigates the influence of electrical and thermal human tissue parameters ... more ABSTRACT This paper investigates the influence of electrical and thermal human tissue parameters on the heating of a body illuminated by a millimeter plane electromagnetic wave. A stochastic approach is considered with a three-layer model of the body: it is found that the parameters of skin play a major role.

Research paper thumbnail of On the use of TEM cells for the calibration of power frequency electric field meters

Measurement, 2010

ABSTRACT This paper focuses on the performances of TEM cells when used in the calibration of powe... more ABSTRACT This paper focuses on the performances of TEM cells when used in the calibration of power frequency environmental electric field meters. The spatial non-uniformity of the electric field inside a TEM cell is analyzed through experimental investigations and three-dimensional Boundary Element modeling to evaluate the field experienced by the sensing elements of actual 3D meter probes. The perturbation caused by the probe support is also taken into account. The uncertainty component associated with the spatial non-uniformity in the volume taken up by typical power and low frequency field probes is estimated. The field non-uniformity is also evaluated in relation to the use of TEM cells of reduced size. Finally, the field non-uniformity is exploited to predict the performance of an actual field meter operating in significant field gradients.

Research paper thumbnail of Evaluation of Electromagnetic Phenomena Induced by Transcranial Magnetic Stimulation

IEEE Transactions on Magnetics, 2000

ABSTRACT The electric current densities induced inside a human head by transcranial magnetic stim... more ABSTRACT The electric current densities induced inside a human head by transcranial magnetic stimulations are evaluated through a hybrid finite-element–boundary-element method applied to an anatomical model based on voxel data set. The results of the computational procedure are first validated considering two model problems. Then, the induced E-field within the head of Duke model of the Virtual Family are simulated for two different transcranial magnetic stimulation coils, evaluating the impact of tissue properties variability and model resolution.

Research paper thumbnail of A boundary element estimate of radiated emissions produced by unknown sources

International Symposium on Electromagnetic Compatibility - EMC EUROPE, 2012

ABSTRACT The paper presents a Boundary Element procedure able to predict the emission radiated by... more ABSTRACT The paper presents a Boundary Element procedure able to predict the emission radiated by unknown sources, starting from the knowledge of the electromagnetic field in a limited number of points placed on a surface surrounding the sources. The proposed approach is tested by analyzing the field distribution obtained as a superposition of the emissions produced by four different radiating elements. The influence of the number of points on the accuracy and the possibility of simplifying the measurement procedure are finally investigated.

Research paper thumbnail of Valutazione di emissioni elettromagnetiche prodotte da impianti in alta tensione continua

Research paper thumbnail of Uncertainty Estimate Associated With the Electric Field Induced Inside Human Bodies by Unknown LF Sources

IEEE Transactions on Instrumentation and Measurement, 2000

ABSTRACT This paper is focused on the uncertainty estimate of a hybrid experimental-numerical pro... more ABSTRACT This paper is focused on the uncertainty estimate of a hybrid experimental-numerical procedure for the evaluation of the electric field induced in a human model radiated by a low-frequency magnetic field produced by unknown sources. The procedure is based on magnetic field measurements in a limited number of points around the field source and makes use of the boundary element method. The uncertainty contribution due to the measurement operations is taken into account by evaluating its propagation through the computational process using a Monte Carlo approach coupled to a discrete numerical technique. The procedure is then applied to the case of a body exposed to the field generated by a Helmholtz coil system. The results show that the relative standard uncertainty of the estimated induced electric field is within a few percent.

Research paper thumbnail of Massively Parallelized Boundary Element Simulation of Voxel-Based Human Models Exposed to MRI Fields

IEEE Transactions on Magnetics, 2000

ABSTRACT Boundary element and hybrid boundary element—finite element approaches are applied to th... more ABSTRACT Boundary element and hybrid boundary element—finite element approaches are applied to the computation of induced electric field and specific absorption rate in voxel-based human models undergoing magnetic resonance imaging. Due to the very large size of the algebraic system, the procedure uses an iterative GMRES solver recalculating the element matrix at each iteration. A suitable processing of the Green integrals and a massively parallelized algorithm, based on the use of graphical processing units, leads to a strong reduction of the computational time.

Research paper thumbnail of Metrology to support therapeutic and diagnostic techniques based on electromagnetics and nanomagnetics

Rendiconti Lincei, 2015

ABSTRACT This paper presents an overview of the recent research activities carried on at INRIM in... more ABSTRACT This paper presents an overview of the recent research activities carried on at INRIM in the field of metrology for healthcare, aiming at supporting therapeutic and diagnostic techniques based on electromagnetics and nanomagnetics. Attention is here specifically focused on three research topics, respectively related to electromagnetic dosimetry for MR-safety, production and characterization of magnetic Ni80Fe20 nanodisks for biomedical applications and development of modeling tools to support the design of novel biosensors.

Research paper thumbnail of Motion-Induced Fields in Magnetic Resonance Imaging: Are the Dielectric Currents Really Negligible?

IEEE Magnetics Letters, 2015

ABSTRACT This paper deals with the exposure of humans moving through the stray stationary magneti... more ABSTRACT This paper deals with the exposure of humans moving through the stray stationary magnetic field produced by magnetic resonance imaging scanners. In particular, the work evaluates the influence of the dielectric currents, whose effects have been disregarded up to now, despite the very high permittivity values obtained by extrapolation based on the most common dispersion models of tissue properties. The analysis is carried out by considering a high-resolution anatomical model through an original numerical procedure that includes the dielectric phenomena. The results prove that the high values of the dielectric permittivity produce limited, but nonnegligible variations on the induced current density, while weakly influencing the electric field. Finally, the stability of the results with respect to variations of the dielectric permittivity practically removes the need for an accurate measurement of such a parameter that is affected by high uncertainties at very low frequencies.

Research paper thumbnail of Solution of Large Complex BEM Systems Derived From High-Resolution Human Models

IEEE Transactions on Magnetics, 2000

ABSTRACT The aim of this paper is the investigation of the numerical properties of the boundary e... more ABSTRACT The aim of this paper is the investigation of the numerical properties of the boundary element method (BEM) when applied to dosimetric analysis of human exposure to electromagnetic fields adopting high resolution voxel-based data sets. Some test problems are analyzed considering the neck region of the human body radiated by a loop antenna. Different strategies in the development of the problem equations are proposed and their effects on the conditioning of the BEM matrix are discussed. Several direct and iterative solvers are applied to the model problems and their efficiency is compared.

Research paper thumbnail of Collateral Thermal Effect of MRI-LINAC Gradient Coils on Metallic Hip Prostheses

IEEE Transactions on Magnetics, 2014

ABSTRACT This paper aims at evaluating the thermal effects produced by the gradient coils on pati... more ABSTRACT This paper aims at evaluating the thermal effects produced by the gradient coils on patients carrying metallic hip prostheses when undergoing check-up in combined magnetic resonance imaging with a linear accelerator systems. The computations are performed by two noncommercial codes specifically developed by the authors for voxel based human models. The electromagnetic field problem is solved by a hybrid finite element-boundary element technique implemented in a massively parallelized GPU system. The temperature elevation due to the electromagnetic exposure is then evaluated through a finite element code. The computations are performed for a large number of situations, considering both radial and axial arrangements of the patient.

Research paper thumbnail of A model to relate SAR to surface field measurements in human phantoms

Research paper thumbnail of A Potential-based Formulation for Motion-Induced Electric Fields in MRI

IEEE Transactions on Magnetics, 2015