Pavel Karban

University of West Bohemia ·  Department of Theory of Electrical Engineering

Contemporary beam-forming antenna arrays often use a large number of individual elements, sometimes hundreds or more, to achieve high gain for advanced applications like radar, space communication, and next-gen cellular networks. These arrays are complex and costly due to the need for precise amplitude and phase adjustments across the elements. The...

There is a great potential in small satellite technology for testing new sensors, processes, and technologies for space applications. Antennas need careful design when developing a small satellite to establish stable communication between the ground station and the satellite. This work is motivated by the design of an antenna array for a future rot...

Method of optimizing the distance between individual elements in the antenna array is presented. Based on the verification of the analytical model for one defined rectangular patch antenna and subsequently for the antenna array, the sweep analysis was performed for variant voltage and phase values on each element of the array. The results were used...

Benchmarking is essential for testing new numerical analysis codes. Their solution is crucial both for testing the partial differential equation solvers and both for the optimization methods. Especially, nature-inspired optimization algorithm-based solvers, where is an important study is to use benchmark functions to test how the new algorithm may...

Cost optimization of power transformers is a complex engineering task. The design engineers have to solve this multidisciplinary, non-linear optimization problem in a very short-time. Due to the importance of the topic, numerous optimization methods have been developed in the industry to solve this problem. These methods generally use different, si...

The bio-inspired algorithms are novel, modern, and efficient tools for the design of electrical machines. However, from the mathematical point of view, these problems belong to the most general branch of non-linear optimization problems, where these tools cannot guarantee that a global minimum is found. The numerical cost and the accuracy of these...

Benchmarking is essential for testing new numerical analysis codes. Their solution is crucial both for testing the partial differential equation solvers and both for the optimization methods. Especially, nature-inspired optimization algorithm-based solvers, where is an important study is to use benchmark functions to test how the new algorithm may...

Two powerful and versatile code packages (Agros Suite and Ārtap) are presented for design and optimization of technical devices and systems. Agros Suite represents an environment for numerical solution of systems consisting of partial differential equations (PDEs) of the second order by a higher-order finite element method with a lot of further adv...

Since large power transformers are custom-made, and their design process is a labor-intensive task, their design process is split into different parts. In tendering, the price calculation is based on the preliminary design of the transformer. Due to the complexity of this task, it belongs to the most general branch of discrete, non-linear mathemati...

Nowadays, there is a huge interest in the design of medium frequency transformers. Due to their high power density and relatively good efficiency. These transformers are still used in wind farms and traction, where not only the efficiency, but the overall size and weight of the transformer are important design criteria. However, the determination o...

Purpose The purpose of this paper is to compare different reduced-order models for models of control of induction brazing process. In the presented application, the problem is to reconstruct temperature at the points of interests (hot spots) from information measured at accessible places. Design/methodology/approach The paper describes the process...

A novel technique of optimizing selected models of electroheat processes (laser or induction-assisted laser welding, cladding, and so on) is presented, based on the calibration of temperature-dependent material properties. These properties often exhibit uncertainties that negatively influence the quality of the results. Their calibration starts fro...

Since large power transformers are custom-made, and their design process is a labor-intensive task, their design process is split into different parts. In tendering, the price calculation is based on the preliminary design of the transformer. Due to the complexity of this task, it belongs to the most general branch of discrete, non-linear mathemati...

The main goal of the Artap project is to provide an extensive infrastructure for robust design optimization, where usually many different numerical solvers have to be used together and the impact of the manufacturing uncertainties have to be minimized. Artap is an open-source software platform, developed jointly with the coupled numerical field sol...

Purpose The purpose of this paper is to present the calibration of a laser welding model suitable for solving problems with input data that are either unknown or known only approximately. Design/methodology/approach The calibration starts from the measured temperature profile of the weld, and the aim is to get a similar profile by the solution of...

The main goal of the Artap project is to provide an extensive infrastructure for robust design optimization, where usually many different numerical solvers have to be used together and the impact of the manufacturing uncertainties have to be minimized. Artap is an open-source software platform, developed jointly with the coupled numerical field sol...

Design of electrical machines with low carbon footprint is an actual topic in the industry. Total cost of ownership is the standardized methodology to consider the lifetime costs of a power transformer already in the pre-concept design stage. There still does not exist a widely accepted method to calculate the carbon footprint of power transformers...

Design of electrical machines with low carbon footprint is an actual topic in the industry. Total cost of ownership is the standardized methodology to consider the lifetime costs of a power transformer already in the pre-concept design stage. There still does not exist a widely accepted method to calculate the carbon footprint of power transformers...

Accurate temperature control is an important part of an induction brazing process, because of a small difference between melting points of aluminum and soldering material. However, direct measurement of the local temperature at the spot of brazing is not possible in a production line. This temperature can be calculated from the results of indirect...

A method of finding the temperature dependences of physical parameters of metals is proposed and discussed. The method is based on the combination of measurement of the surface temperature of the material and subsequent solution of the inverse problem using the multi-parametric optimization. Particular steps and algorithms are illustrated with an e...

Purpose A novel technique for control of complex physical processes based on the solution of their sufficiently accurate models is presented. The technique works with the model order reduction (MOR), which significantly accelerates the solution at a still acceptable uncertainty. Its advantages are illustrated with an example of induction brazing....

Long-range in-body biomedical telemetry enables monitoring of physiological parameters while maintaining mobility and freedom of movement. This emerging technology creates new applications in medicine, clinical research, wellness, and defense. Current in-body biotelemetry devices operate within about a meter around a user that limits their applicab...

Autonomous wireless body-implanted devices for biotelemetry, telemedicine, and neural interfacing constitute an emerging technology providing powerful capabilities for medicine and clinical research. We study the through-tissue electromagnetic propagation mechanisms, derive the optimal frequency range, and obtain the maximum achievable efficiency f...

An alternative fully adaptive finite element approach is used for modeling fast transient phenomena on overhead lines. The methodology is based on rewriting the hyperbolic transmission equation for voltage to two specific equations where one unknown is the voltage itself and another unknown is its partial derivative with respect to time. The system...

In-body devices for wireless biotelemetry and neural interfacing could empower many breakthroughs in medicine and clinical research. Despite significant progress in antenna design, improving the radiation performance of miniature in-body devices remains a major challenge because, for the time being, they are able to operate at distances of only up...

Progress in implantable and ingestible wireless biotelemetry requires versatile and efficient antennas to communicate reliably from a body. We propose an ultra-miniature 434 MHz antenna immune to impedance detuning caused by varying electromagnetic properties of the surrounding biological environment. It is designed for a standard input impedance o...

A new approach to estimation of unknown material parameters and boundary conditions of physical models was developed. The approach is based on processing measured data by advanced optimization techniques connected with penalization. The data are supposed to be in the form of random variables with normal probability distributions. Several examples w...

The Bayes approach is used for solution of benchmark problems 22 and 25. The main purpose of the paper is to evaluate its applicability for solving complex technical problems (up to now, this technique was only very rarely used in the domain of such tasks). The parameters of this approach are compared with characteristics of several other heuristic...

We propose a versatile 434 MHz in-body capsule antenna suitable for ingestible and variety of implantable applications. The low profile conformal antenna is synthesized using a hybrid analytical–numerical approach and optimized for robust operation at 434 MHz inside a 17 mm long biocompatible encapsulation (7 mm diameter). The antenna remains match...

The paper deals with calculation of critical intensity of the radiant component, which is important for setting fire-dangerous area in surroundings fire open area. The algorithm is based on numerical continuation method.

A novel way of calibration (estimation of unknown material parameters and boundary conditions) of physical models is presented, based on measured data and advanced optimization and penalization techniques. The methodology is illustrated with an example whose results are discussed.

When designing a TEM transmission line cell for electromagnetic compatibility susceptibility or immunity tests, its input impedance must be properly defined in order to deliver the maximum power to the device under test. The closed-form solution, relating the cell geometry with the characteristic impedance Zc, is possible only for the simplest “can...

Optimization of the process of induction clamping is presented, consisting in finding the optimum shape of the field coil. The objective function takes into account the required expansion of the bore of the clamping head. While the forward problem is, as a coupled task with nonlinear and nonstationary interaction of three physical fields (magnetic...

Body-centric wireless networking and communications is an emerging 4G technology for short (1-5 m) and very short (below 1 m) range communications systems, used to connect devices worn on (or in) the body, or between two people in close proximity. It has a great potential for applications in healthcare delivery, entertainment, surveillance, and eme...

The electronic implants for biomedical applications came out in mid-50s with the invention of the first pacemakers. This healthcare innovation exposed the potential and revealed the vast opportunities in the field of implantable electronic devices, enabling new ways of diagnostics and treatments maintaining the patient mobility. So, the idea of wir...

The utilization of the cross-correlation technique in pulsed eddy current testing is described and illustrated with an example of an artificial defect in an electrically conductive steel plate. The investigated eddy current probe is of a differential type, consisting of one excitation and two sensing coils with a ferrite magnetic circuit. The numer...

Comparison of open-source libraries for solving systems of algebraic equations is carried out. Attention is paid mainly to solvers (or preconditioners) using the method called algebraic multigrid. For comparison, several direct and iterative solvers were chosen, such as MUMPS, UMFPACK, TRILINOS, PARALUTION and PETSc. Utilization of these packages i...

The goal of this paper is to present a methodology for numerical analysis of 3D numerical model of a transformer for reducing negative noise impact on the environment. The task is to map structural dynamics and vibrations of its selected parts. The main aim of this paper is to describe the numerical analysis of natural frequencies and demonstrate t...

Electrostatic separation of triboelectrically charged plastic particles is investigated and verified on an experimental device. After presenting the fundamentals of the process in the introductory part, attention is paid to the stucture of the device and functions of its particular elements. The last part of the paper discusses the results of exper...

A fast and efficient algorithm is presented allowing a firefighter dressed in a smart firefighter protective suit continuously informing him about the time that he can still safely spend in a burning bulding, which is characterized by an dynamic environment of time-variable temperature. The algorithm starts from precalculated time evolution of temp...

Adaptive techniques for modeling fast transients on high-voltage lines are proposed and evaluated. These techniques seem to be a powerful tool for their higher-order finite element analysis, bringing considerable savings both in memory and time of computation. A typical example is presented showing the advantage of this approach.

We propose an approach to increase the operating range and matching stability of in-body ingestible or implantable capsule antennas. It involves using high permittivity biocompatible superstrate on a high-Q narrowband microstrip antenna. In this way, the antenna–body coupling can be significantly reduced, resulting in improved detuning immunity, in...

This study deals with innovated eddy current testing-swept frequency eddy current technique, which allows non-destructive evaluation of materials with non-zero conductivity. The basis of this novel method is a change of frequency of exciting signal in a wide range while the testing probe is in a fixed position. The swept frequency technique enables...

A new way of induction heating of cylindrical nonmagnetic billets is modelled and experimentally verified. This technology, among others, makes it possible to obtain a required temperature profile of the heated billet along its length. The billet is heated by rotation in a stationary magnetic field produced by high-parameter permanent magnets. The...

An alternative way of determining the temperature-dependent characteristics of metals is presented. The method that is relatively simple and cheap is suitable mainly for metals with lower melting points. The paper starts with the experimental investigation of the melting process of the Field metal in an induction furnace, which provides all necessa...

A device for electrostatic separation of triboelectrically charged plastic particles is modeled and optimized. Electric field in the system is solved numerically by a fully adaptive higher-order finite element method. The movement of particles in the device is determined by an adaptive Runge–Kutta–Fehlberg algorithm. The shape optimization of the e...

A magneto-thermal inverse problem, dealing with the optimal design of an induction heating device, is proposed as a benchmark. The coupled-field problem is analysed by means of a higher order finite element method. Then the optimal design problem is solved in terms of the Pareto front trading off two conflicting objective functions.

An alternative way of induction heating of nonmagnetic cylindrical billets is modeled. The billet rotates in static magnetic field generated by permanent magnets. The mathematical model of the process consisting of two second-order partial differential equations describing the distributions of magnetic and temperature fields is solved numerically i...

Two important parameters of triboelectric separation of plastic particles are analyzed: the distribution of their electric charges and their critical velocity (velocity, at which the trajectories of falling particles are not longer significantly influenced by the applied electric field). The analysis is performed by a combination of experimental an...

Shape optimization of the plunger of an electromagnetic actuator is carried out in order to obtain linear static characteristic of the device. The distribution of magnetic field in the system is modelled by a higher-order finite element technique using an effective implementation of the Newton method. The static characteristic of the device is dete...

The pulsed eddy current defectoscopy belongs to powerful methods of nondestructive testing of metal bodies aimed at revealing various changes of their material parameters, defects, cracks, and other undesirable imperfections. The quality of their identification strongly depends on the tools for evaluation of signals monitored by the measuring syste...

An advanced way of induction heating of nonmagnetic billets is discussed and modeled. The billet rotates in a stationary magnetic field produced by unmoving high-parameter permanent magnets fixed on magnetic circuit of an appropriate shape. The mathematical model of the problem consisting of two coupled partial differential equations is solved nume...

The design optimization of an induction heating device is considered. The non-linear multi-physics analysis is carried out by means of finite-element method, while the optimal design problem is solved by NSGA-II genetic algorithm. A comparison with the results obtained by a simplified linear analysis is shown. The original contribution of this pape...

Induction heating of non-magnetic cylindrical billets is modeled. The billet rotates in static magnetic field generated by appropriately distributed permanent magnets. The mathematical model of the process consists of two second-order partial differential equations describing the distributions of magnetic and temperature fields. Its solution is sol...

An alternative higher-order Eggshell method is proposed for determining forces acting on a ferromagnetic body in magnetic field. The strongly nonlinear problem is solved by the Newton method effectively implemented in our codes Agros2D and Hermes. The computation exhibits substantially higher parameters (accuracy, time of solution) than the algorit...

Shape optimization of electrodes for the device for electrostatic separation of triboelectrically charged plastic particles is carried out. The objective function maximizes the efficiency of separation consisting in the highest possible number of particles falling down to the prescribed bins. Electric field in the system is solved numerically, usin...

Parallel plate antennas (or improved TEM-cell, strip line antenna, etc.) are used in electromagnetic compatibility for a susceptibility testing. The well-designed antenna represents transmission line with transverse electromagnetic (TEM) wave propagation and the electromagnetic field between plates is uniform. In the area with the uniform field are...

New code Agros2D for 2D numerical solution of coupled problems is presented. This code is based on the fully adaptive higher-order finite element method and works with library Hermes2D containing the most advanced numerical algorithms for the numerical processing of systems of second-order partial differential equations. It is characterized by seve...

The process of induction heating of cylindrical nonmagnetic billets is modeled and optimized. An unmovable billet is placed in rotating magnetic field generated by permanent magnets fixed in an external rotor driven by an asynchronous motor by means of a teeth gear. The coupled model of the problem consisting of two partial differential equations d...

Numerical modeling of harmonic acoustic field produced by a common commercial loudspeaker is carried out. The goal is to obtain the directional characteristic of the device. So far, these characteristics could only be obtained by measurements, which was very complicated and also expensive. Another benefit of the model consists in obtaining a refere...