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Collection's Items (Sorted by Submit Date in Descending order): 1 to 20 of 43
Juřík, Martin , Šmídl, Václav , Mach, František
Trade-off between resolution and frame rate of visual tracking of mini-robots on an experimental planar platform

Accurate and fast visual localization is required in many applications of mini-robotics. Obtaining the best possible result fora given platform requires a balanced combination of camera settings and efficient image processing of the acquired image. Inthis paper, we study the trade-off betwee...

Petrášová, Iveta , Kotlan, Václav , Šroubová, Lenka , Karban, Pavel , Doležel, Ivo
Calibration of laser welding model based on optimization techniques

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&#...

Smolyanov, Ivan Alexandrovich , Kotlan, Václav , Doležel, Ivo
Optimal heat induction treatment of titanium alloys

Purpose – This paper aims to propose a number of approaches to reduce the temperature gradient of titanium billets in the heat treatment process. Design/methodology/approach – Modeling physical processes in the induction unit is calculated by the finite element method. Required pow...

Sodomka, Ondřej , Skřivan, Vojtěch , Mach, František
Magnetic forces behind hyperelastic behavior of magnetorheological elastomers

A magnetic and nonlinear structural mechanic coupled problem is discussed concerning the behaviour of a magnetorheological elastomer. Material properties and hyperelastic character of the material were found by measurements. Based on the measurements and computations, a coupled mathematical model is&#...

Petrášová, Iveta , Karban, Pavel , Kotlan, Václav , Doležel, Ivo
Optimization of selected electroheat models based on calibration of material properties

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&#...

Orosz, Tamás , Pánek, David , Karban, Pavel
FEM based preliminary design optimization in case of large power transformers

Pánek, David , Karban, Pavel , Orosz, Tamás , Doležel, Ivo
Comparison of simplified techniques for solving selected coupled electroheat problems

Kotlan, Václav , Hamar, Roman , Smolyanov, Ivan Alexandrovich , Doležel, Ivo
Induction-assisted laser welding taking into account phase changes

Purpose – The paper aims to describe the modeling of the induction-assisted laser welding process taking into account the keyhole effect and phase changes in the material. Design/methodology/approach – A sophisticated mathematical model of the above heat treatment process is presented,&...

Pavlíček, Karel , Kotlan, Václav , Doležel, Ivo
Applicability and comparison of surrogate techniques for modeling of selected heating problems

Possibilities of using surrogate techniques for modeling selected strongly nonlinear coupled problems of heating are evaluated. The main purpose is to significantly reduce the computing time in the case of computations of many variants of a given task by the finite element method o...

Štork, Milan , Mayer, Daniel
Modified Tellegen Principle Used for Power and Energy Systems Modeling

The paper deals with a problem of modeling of dynamic systems. The proposed approach to the problem solution is based on modified Tellegen’s theorem well known from electrical engineering. The novelty of this approach is that it is based on the instantaneous power calculation ...

Štork, Milan , Mayer, Daniel
RLC Ladder Oscillators Controlled by Energy Approach

The following topics are dealt with: artificial satellites; CMOS integrated circuits; switching convertors; reliability; DC-DC power convertors; failure analysis; oscillators; capacitors; solar power satellites; network topology.

Štork, Milan , Mayer, Daniel , Hrušák, Josef
Generalized tellegen principle used for energy method for systems modeling

This paper deals with dissipativity, stability, chaotic behavior and related structural properties of a relatively broad class of finite dimensional strictly causal systems. The class of nonlinear systems under consideration is described in the state-space representation form. System properties are&#x...

Pánek, David , Karban, Pavel , Doležel, Ivo
Calibration of numerical model of magnetic induction brazing

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 optimiza...

Štork, Milan , Mayer, Daniel
Direct currents in power transformers

The article is devoted to the physical nature of geomagnetism, magnetic storms and methods of predicting their origin and deals with geomagnetic induced currents called GIC (Geomagnetically Induced Currents) and their effect on power transformers. A simplified, single-phase transmission system is...

Kotlan, Václav , Hamar, Roman , Pánek, David , Doležel, Ivo
Model of depositing layer on cylindrical surface produced by induction-assisted laser cladding process

A model of hybrid cladding on a cylindrical surface is built and numerically solved. Heating of both substrate and the powder material to be deposited on its surface is realized by laser beam and preheating inductor. The task represents a hard-coupled electromagnetic-thermal problem...

Behúň, Lukáš , Slobodník, Karel
Harmonic and pulsed eddy current testing methods as tools for surface and subsurface defect evaluation

In most publications eddy current testing (ECT) methods are said to be suitable for surface defects up to several millimeters. This paper aims to evaluate the detection capabilities of eddy current testing based on two examples of modern approach. One of them is a harmonic...

Doležel, Ivo , Kotlan, Václav , Hamar, Roman , Pánek, David
Numerical solution of electroheat problems with time-varying geometries

Novel approach to modeling of 3D coupled electroheat problems with time-varying geometries is presented. Instead of time-expensive remeshing of the whole system in every time step it is used the initial mesh that takes into account the expected geometric changes. In the course of&#...

Nikolayev, Denys , Zhadobov, Maxim , Karban, Pavel , Sauleau, Ronan
Electromagnetic radiation efficiency of body-implanted devices

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 th...

Kotlan, Václav , Hamar, Roman , Šroubová, Lenka , Doležel, Ivo
Hybrid realization of fillet weld

Purpose: A model of hybrid fillet welding is built and solved. No additional material (welding rod, etc.) is used. Heating of the welded parts is realized by laser beam with induction preheating and/or postheating. The purpose of these operations is to reduce the temperature&#...

Karban, Pavel , Pánek, David , Doležel, Ivo
Model of induction brazing of nonmagnetic metals using model order reduction approach

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 advanta...

Collection's Items (Sorted by Submit Date in Descending order): 1 to 20 of 43