Jacek Starzynski

Simulation of magnetic stimulation of the brain

The paper presents a computer simulation of the transcranial magnetic stimulation of the brain with a low-frequency magnetic field, a technique which is proposed to replace the electroconvulsive treatment in psychiatry. The field model is based on the T-/spl Omega/ formulation, that, by the low electric conductivity and constant magnetic permeability of the human tissue, allows us to build a finite-element model of the head only.

Optimal design of the coils of an electromagnetic flow meter

A new method of optimal design of the excitation coil for an electromagnetic flow meter is presented, The main goal is to form an algorithm which will be able to deal with natural channels of any shape with conductive beds/banks. The presented method allows an engineer to design an optimal coil to obtain homogeneity of the special weight vector W. This homogeneity provides that the voltage measured between the electrodes of the flow meter will be proportional to the mean velocity of the liquid in the channel. The optimization of the coil shape is carried out through minimization of an objective function defined on the basis of a finite element method 2D model of the cross-section of the channel.

3-D approach to designing the excitation coil of an electromagnetic flowmeter

This paper presents 3D hybrid numerical model of electromagnetic flowmeter. Compared to the 2D model used before it is advantageous for the quality of computer simulation, but at the cost of computational burden. Our aim was to compare characteristics of the flowmeter obtained from 2D and 3D simulations to check if faster 2D models can be used for computer aided design of the device. The results of research show that 3D model must be used for optimal design of some parameters of the coil.

Electromagnetic flowmeters for open channels - two-dimensional approach to design procedures

In this paper, we present a two-dimensional (2-D) ap- proach to electromagnetic flowmeters design. Several design pro- cedures that have been prepared and tested for designing electro- magnetic flowmeters for open channels are presented. The authors present a simplified 2-D mathematical model of a flowmeter for de- termining the cross-sectional shape and length of an excitation coil. We analyze two groups of flow channels: rectangular nonconduc- tive flow channels, and conductive flow channel with any shape of a cross section. Finally a dry calibration procedure determines the transfer function of a flowmeter.

A comparison of two models of electrodes for ECT simulations

This paper discusses some numerical aspects of the simulation of electroconvulsive therapy (ECT). A realistic finite-element model of the human head is used to discuss two approaches to modeling the electrodes applied to human head skin. The first approach models the electrode by a mixed-boundary condition, while the second one uses additional subdomain imitating electrode-to-skin contact for that purpose [three-dimensional (3-D) model]. An algorithm of grid modification used to add an external subdomain modeling the electrode contact resistance is presented. The authors examine the influence of the electrode model on the convergence speed of the iterative solver. The authors state that the 3-D model is better conditioned, and, thus, it converges faster

Numerical model of magnetic stimulation with metal implants

The paper presents numerical model of the magnetic stimulation of the human body. The proposed model allows one to calculate eddy current distribution inside the body with a metal implant, which can be ferromagnetic or diamagnetic. A hybrid Toarr-Omega, Aoarr finite-element method formulation is used, where Omega is calculated by semi-analytical integration over a boundary of the conducting region. The three-step algorithm is presented, with discussion about implementation and computational problems

Internet application concept to trivialize EMF biomedical computing

Purpose – The purpose of this paper is to describe a new concept of a computer system devoted to simulations of electromagnetic fields inside the human body. The main idea is based on application of the cloud computing approach to the electromagnetic simulator for inexperienced operators.Design/methodology/approach – Modular design of the system is based on web technologies. The logic of simulation processes is stored in the form of scenarios consisting of several simple steps.Findings – The authors found that a system based on a predefined, precise scenario will help an inexperienced user to solve realistic EMF simulations using state‐of‐the‐art technology. Highly modular application could be easily extended to the new functionality provided by independent programs (Processors) utilizing any type of a dedicated hardware platform.Practical implications – The remote computing is known by computer science for its early beginning, but extraordinary growth of the internet network is renewing this term for the...

Eliminating short ending effects in the primary transducer of electromagnetic flow meters

This paper describes a new method of primary transducer length optimization for electromagnetic flow meters. The method is based on eliminating a short ending effect that appears in the area where the magnetic field rapidly vanishes. The method uses numerical tools compatible with the cross section of the excitation coil design. It is based on a simple two-dimensional mathematical model of the primary transducer. The paper presents results of calculations for two water-to-ground conductivity ratios and for a rectangular flow channel.

A novel approach to eliminating short ending effects in the primary transducer of electromagnetic flow meter

This paper describes a new method of primary transducer length optimization for electromagnetic flow meters. The method presented is based on eliminating a short ending effect which appears in the area where the magnetic field rapidly vanishes. The authors focused on the method which uses similar numerical tools as the shape design of the cross-section of the excitation coil. The method is based on a simple 2D mathematical model of the primary transducer. Some results of calculations for two water to ground conductivities ratio and for the rectangular flow channel are discussed.

Benchmark problems for optimal shape design for 2D eddy currents

Two new benchmark inverse problems for eddy currents are proposed. The first originates in the optimal design of the tubular inductive heater. The authors’ goal is to offer a simple problem which will check whether new software is able to minimize a multimodal objective function. The second benchmark is a simplified model of a hardening device. The purpose of this problem is to test the ability of the software to deal with different design parameters. This benchmark can be easily extended for more complicated, coupled fields problems. For both benchmarks reference standard solutions are presented. They were obtained using a finite element package for electromagnetics, developed by the authors.