Robert Szmurlo

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

Teaching software modeling in a simulated project environment

Teaching software engineering in the academia always faces the problem of inability to show problems of real life development projects. The courses seem to be unable to properly show the need of using software modeling as important means of coping with complexity and handling communication within the project. The paper presents format of a course that tries to overcome this. It focuses on application of modeling tools in a realistic software engineering environment. The objective is to teach best practices of software design and implementation with the use of UML. The students can practice design and communication techniques based around CASE tools in teams of 12 to 14 people. The paper summarizes 5 years of experience in teaching modeling with CASE tools. Authors present a concept of how to simulate the roles of architects, designers and programmers as close to reality as possible. The paper also discusses the problems of organizing laboratory work for a large group of students. Authors present the tasks and their arrangement during the course.

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...

Design of AC-DC Grid Connected Converter using Multi-Objective Optimization

Abstract Power electronic circuits, in particular AC-DC converters are complex systems, many different parameters and objectives have to be taken into account during the design process. Implementation of Multi-Objective Optimization (MOO) seems to be attractive idea, which used as designer supporting tool gives possibility for better analysis of the designed system. This paper presents a short introduction to the MOO applied in the field of power electronics. Short introduction to the subject is given in section I. Then, optimization process and its elements are briefly described in section II. Design procedure with proposed optimization parameters and performance indices for AC-DC Grid Connected Converter (GCC) interfacing distributed systems is introduced in section III. Some preliminary optimization results, achieved on the basis of analytical and simulation study, are shown at each stage of designing process. Described optimization parameters and performance indices are part of developed global optimization method dedicated for ACDC GCC introduced in section IV. Described optimization method is under development and only short introduction and basic assumptions are presented. In section V laboratory prototype of high efficient and compact 14 kVA AC-DC converter is introduced. The converter is elaborated based on performed designing and optimization procedure with the use of silicon carbide (SiC) power semiconductors. Finally, the paper is summarized and concluded in section VI. In presented work theoretical research are conducted in parallel with laboratory prototyping e.g. all theoretical ideas are verified in laboratory using modern DSP microcontrollers and prototypes of the ACDC GCC.

Numerical model of vagus nerve electrical stimulation

Purpose – The electric stimulation of the vagus nerve is used to obtain therapeutic results in epilepsy, depression and Alzheimer diseases. The purpose of this paper is to show numerical model of stimulation, focusing on the mathematical approach to modeling a phenomenon of neural cells activation and its propagation in the nerve.Design/methodology/approach – The paper presents a model based on the bidomain theory. It uses two continuous, averaged domains which depict the intra‐ and extra‐cellular domains and are connected with the membrane ionic currents. The numerical model uses 3D cylindrical model approximating the anatomical shape of the neck. The simulator is based on a time domain finite element method.Findings – The presented approach allows to model the discrete behaviour of the membrane potential in the macroscopic, realistic model of the nerve. The validation of the parameters with the velocity of activation propagations suggests the strong disscussion on physical interpretation to the bidomain...

Multiscale Finite Element Model of the Electrically Active Neural Tissue

The paper presents a mathematical approach to modeling of continuous, spatial and active neural tissue. It combines a nonlinear discrete cell membrane model with spatial bidomain model into one multiscale problem. The bidomain allows us to simulate the action potential (AP) propagation in the selected human brain neural tissues. The evoked potentials are stimulated by applying artificial stimulation current in the nonlinear cell model which is equivalent to direct injection of current by the internal electrode. Such approach can be used to model electrical stimulation of the neural tissue during the surgical operations or stimulation by surgically implanted devices. The model can be extended to deal with external electric or magnetic stimulus. The main focus of the paper is put on numerical adaptation of the bidomain commonly used for modeling human heart activity to new area of interest: human neural system. The authors present two formulations of the bidomain model. The first uses a pair of intra and extracellular potentials, and the second uses a pair of extracellular potential and membrane voltage. Both formulations are compared with respect to results and numerical efficiency.

Bidomain formulation for modeling brain activity propagation

The paper presents a mathematical approach to the modeling of continuous active neural tissue together with a nonlinear discrete cell model. The main focus is put on the numerical formulation adapted from the bidomain model for the human heart. The bidomain model uses two scalar electrical potentials: intra- and extracellular to simulate propagation of the action potential from the spiking neurons in the white and gray matter tissues. The evoked potentials are forced by applying artificial stimulation current through the neuron membrane. The authors introduced new values of material parameters and neuron models to adequately simulate the brain activity

Distributed evolutionary algorithm for optimization in electromagnetics

This paper presents a distributed universal evolutionary optimization environment designed for optimal design in electromagnetics. The optimizer can be tuned to act as a genetic algorithm or as an evolutionary strategy. Basic principles of optimizer design are discussed. The system is coded in Java and uses a remote method invocation technique to distribute computational tasks between local and/or remote servers. T.E.A.M Workshop problem 25 was used to estimate parallel performance of the system. An example of application is the optimal location of electrodes for electroconvulsive stimulation is presented

Morphing algorithm for building individualized 3D skeleton model from CT data

There are constant efforts to improve speed and automation of the segmentation process of CT data. We propose a semi-automatic, atlas-based method of building 3D individualized skeletons. The intervention of human operator is minimal and is limited to selection of one voxel for each bone to be segmented, measuring a few distances for a successful reconstruction and approving the final result of an alignment. As a proof of the concept, an example of creating a patient-specific model of a left femur bone is presented. The results are discussed in order to chart the route to an automatic solution. It is believed that the areas like orthopedic operation planning and patient positioning systems could benefit from our method.

Bioelectromagnetic simulation for everyone

Cloud computation technologies open a new perspective for scientific computing. Sophisticated software can now be made available as an on-demand service, reducing costs of maintenance and improving availability of the software to end-users. The paper presents a web based service system for electromagnetic computations. The back-end of the system is built of open-source scientific code. The service is targeted on medical staff and electromagnetic safety engineers which usually are not familiar with electromagnetic field simulation methods but its design allows it to be extended for more demanding, scientific-oriented users. The primary goal of the system is user friendliness for medical and engineering staff combined with flexibility, scalability and extendibility for scientists developing simulation software. These goals were achieved with help of carefully designed concept of configurable usage-scenarios (workflows). The purpose of this paper is to present in detail the concept and implementation of scientific scenarios.