Motor responses evoked by transcranial magnetic stimulation (TMS) using posterior-anterior (PA) and anterior-posterior (AP) current directions have distinct latencies thresholds. However, the underlying reasons for these differences remain unclear. To quantify in activation sites between PA- AP-TMS. potentials (MEPs) were recorded from five hand arm muscles nine healthy participants both Active motor thresholds determined at 11 coil positions on scalp. Probabilistic modelling was used to...

A fast method for computing the action of shape-differentiated electric field integral equation (EFIE) system matrix to a vector is derived exploiting multilevel multipole algorithm (MLFMA). The proposed used in conjunction with adjoint-variable (AVM) compute shape gradient arbitrary objective functions depending on metallic scatterer. demonstrated numerically by optimizing parabolic reflector illuminated half-wave dipole.

In the case of rotating electrical machines, magnetic forces acting on stator teeth are principal electromagnetic cause vibrations. Based this fact, paper presents a method to compute vibrations an induction motor with aid nodal forces. An accurate computation local or is essential in problems pertaining vibration and noise analysis machines. Virtual work utilized here as derivative energy from Finite Element (FE) solution field problem. The problem then coupled elasticity solver calculate...

. Normal function of the vestibular system can be disturbed using a noninvasive technique called electrical stimulation (EVS), which alters person's sense balance and causes false sensations movement. EVS has been widely used to study system, it recently gained interest as therapeutic tool improve postural stability help those suffering from dysfunction. Yet, understanding how stimulates current intensity needed produce an effect frequencies at occurs have remained unclear.

The purpose of this work is two-fold: first, we successfully validate our open-source tool EOF-Library, which efficiently couples Elmer FEM and OpenFOAM, against COMSOL Multiphysics, a commercial simulation package; second, inform about significant discrepancies between results the experimental data found in series research papers. We reproduce previously published numerical simulations wherein microwaves are supplied to water domain through rectangular waveguide, inducing convective flow....

Abstract Objective. Transcranial magnetic stimulation (TMS) can be used to safely and noninvasively activate brain tissue. However, the characteristic parameters of neuronal activation have been largely unclear. In this work, we propose a novel model develop method infer its from measured motor evoked potential signals. Approach. The connection between due an induced electric field threshold is modeled. posterior distribution are inferred measurement data using Bayes’ formula. measurements...

Abstract Objective. To investigate the reliability and accuracy of manual three-point co-registration in neuronavigated transcranial magnetic stimulation (TMS). The effect error landmark pointing on coil placement induced electric fields was examined. Approach. position TMS head recorded by neuronavigation system 3D scanning for ten healthy participants. differences locations orientations theoretical values between scanned positions were calculated. In addition, sensitivity location Main...

In this article, a novel multigrid-based method is developed for modeling of electric fields and currents in electrically anisotropic heterogeneous media. The useful numerical assessment human exposure to low-frequency electromagnetic fields, which has been typically performed using isotropic models the body. matrix-free based on structured voxelized grids. Numerical tests indicate that all typical benefits multigrid methods, i.e., convergence constant number iterations linear complexity...

The shape representation of planar wire dipole antennas fixed radius is discussed. Away from the feed point can be always represented as a arc-length parametrizable Lipschitz-continuously differentiable curve. applied to classical directivity optimization design problems well impedance problems. By such an optimization, it shown that directive dipoles length (3/2)λ tuned by and real part input λ/2 bounded above if imaginary must small.

An analytical formula for the shape derivative of magnetic field integral equation (MFIE) method moments (MoM) system matrix (or impedance matrix) is derived and validated against finite difference formulas. The motivation computing derivatives stems from adjoint variable methods (AVM). Galerkin constructed by means Rao-Wilton-Glisson (RWG) basis testing functions. yields an representation which same singularity order as integrals appearing in traditional MFIE matrix.

This paper presents the vibration analysis and results of an induction motor through two kinds magneto-mechanical coupling methods. The computation are validated by comparing them with measurements motor. role both magnetic forces magnetostriction examined distinguished based on their contribution to behavior machine. It was found that pole pair number machine can affect way vibrations caused either add up or oppose each other.

This paper presents an efficient method to calculate the magnetic forces on bodies in contact. The are computed through local application of virtual work principle degenerated air-gap elements. results from this compared with those other software and validated measurements a permanent magnet setup. Not only is technique very accurate, but it also reduces computational burden related problematic meshing thin layers. implementation open source finite element having facilities for higher order...

Abstract Microwave devices are widely used in the industry and specialized laboratory analyses. Development of such requires possibility modeling microwave energy distribution specific resonant chambers. Until now, was possible only with use commercial software or limited to cases. The paper presents an open-source module for ELMER solving timeharmonic Maxwell’s equations, allowing waveguide lines. Three test cases different chambers investigated at 2.45 GHz frequency. Modeling results...

For reduction of vibrations and noise electrical machines, the computation magnetic force distributions ensuing deformations are needed. Here we utilize nodalforce method in open-source Finite Element software Elmer to compute an induction motor during start-up.

We derive analytical shape derivative formulas of the system matrix representing electric field integral equation discretized with Raviart-Thomas basis functions. The arising integrals are easy to compute similar methods as entries original matrix. results compared derivatives computed automatic differentiation technique and finite differences, found be in excellent agreement.

This paper presents a novel experimental set up to measure the deformation in an iron sheet under influence of electromagnetic field, and results Finite Element Analysis used for segregating magnetic forces magnetostriction induced mechanical deformation. The are calculated using virtual work principle is modeled by means energy-based model. 3D computations performed open source finite element software Elmer. numerical simulations were analyzed due identified.

Objective.To investigate whether the motor threshold (MT) and location of hotspot in transcranial magnetic stimulation (TMS) can be predicted with computational models induced electric field.Approach.Individualized were constructed from structural resonance images ten healthy participants, fields determined finite element method. The used to optimize direction TMS coil on scalp produce largest field at a predetermined cortical target location. also predict how MT changes as is moved various...

This paper presents an efficient method to calculate the magnetic forces on bodies in contact. The are computed through local application of virtual work principle degenerated airgap elements. These results compared with those from different models and validated measurements a permanent magnet setup. Not only is this technique very accurate, but also reduces computational burden related problematic meshing thin layers.

A flnite element method based on the flrst order system LL ⁄ (FOSLL ) approach is derived for time harmonic Maxwell's equations in three dimensional domains. The solution a potential original fleld sense that U given by = L u. Maxwellian boundary data appears as natural condition. Homogeneous Dirichlet conditions must be imposed, and they are circumvented with weak enforcement of it proved sesquilinear form elliptic space where satisfled weakly.

Ideally sharp edges can be computationally some-what difficult, but the model is theoretically reasonable except for certain ranges of negative material parameters. In quasistatic limit, permittivity wedges appear to support unphysical edge modes with infinite energy, and this theoretical anomaly show up as nonsensical numerical results in both static dynamic simulations.