Amalia Ivanyi

Isotropic vector Preisach particle

Abstract A Preisach-type pseudoparticle is proposed, to describe macroscopic vector magnetic behaviour of isotropic materials. The magnitude of magnetization is computed by means of the classical Preisach model with the projection of field strength on its direction as input. The orientation of the magnetization vector is governed by the equilibrium between its vector product with the field strength and a friction-like opposing torque proportional to the square of its magnitude. The behaviour of the model is studied in various conditions and the results compared to experiments reported in literature.

Hysteresis in rotation magnetic field

The different properties of the vector Jiles–Atherton hysteresis operator is proved under forced H- and B-field supply. Feeding the magnetic material with alternating and circular polarised rotational excitation, the different properties of the model under the input field intensity and the flux density are investigated and the results are proved in figures.

Hysteresis in column systems

In this paper one column of a telescopic construction of a bell tower is investigated. The hinges at the support of the column and at the connecting joint between the upper and lower columns are modelled with rotational springs. The characteristics of the springs are assumed to be non-linear and the hysteresis property of them is represented with the Preisach hysteresis model. The mass of the columns and the bell with the fly are concentrated to the top of the column. The tolling process is simulated with a cycling load. The elements of the column are considered completely rigid. The time iteration of the non-linear equations of the motion is evaluated by the Crank-Nicolson schema and the implemented non-linear hysteresis is handled by the fix-point technique. The numerical simulation of the dynamic system is carried out under different combination of soft, medium and hard hysteresis properties of hinges.

Estimation of error propagation in multiprocessor systems

In high performance computation where the processors evaluate their required algorithm in serial or parallel action the estimation of the error and the error propagation during the computation is important. In the paper the system of the grid-connected processors is considered as a system. To determine the error of the processor a data is sent through on it under its operation and the output data has some error. Taking into account the error of the output data, it can be decomposed into system error and input error. In the paper determination of the error for different processor configurations are evaluated and applied to some grid-connected processor system. Numerical examples represent the developed theory.

A Periodical Loaded Dynamical System

In the paper a Preisach hysteresis model is applied to determine the dynamic behavior of a steel column with a mass on the top and loaded by periodically alternating force. The column is considered as a completely rigid element, while the fixed end of the column is modeled with a rotational spring with hysteresis characteristic. In the solution of the non-linear dynamical equation of the motion the fix-point technique is inserted to the time marching iteration. The cycling time of the force is changing. The results are plotted in figures.

Measuring of rotating magnetic flux in an integrated environment

The paper describes a measuring method and the establishment of a measuring environment for two-dimensional rotating magnetic fluxes and fields. The measuring method relies on measuring currents and voltages in coils attached to the magnetic specimen. For the processing and generating of measuring signals, a PC-based system running Lab View is applied extended with a NI ELVIS II board, and two high performance KIKUSUI bipolar power supplies. The measurement results are satisfactory and show that the measuring environment established is capable of non-destructively capture the two-dimensional magnetic characteristics of the specimen investigated.

Stability of nonlinear iteration in diffusion problems

In this paper, a one dimensional electromagnetic diffusion problem is considered in a half space filled with nonlinear hysteretic media. The material is fed with sinusoidal alternating magnetic field. For the numerical solution of the resulting second order nonlinear partial differential equation, a Finite Difference Time Domain (FDTD) method (the Yee-algorithm) combined with the material Limiting Loop Proximity Hysteresis (LLPH) characteristic is introduced. Stability problems of the numerical method is examined on the basis of the resulted attractor of the iterative map, which exhibits period-doubling bifurcations and chaotic behavior under certain parameter values. The stability analysis based on this attractor is focusing on the reasons behind the instability of the implicit inner iteration.

Application of hysteresis in FEM modeling of vapor-liquid phase transitions

In this paper a new, phenomenological, temperature dependent hysteresis model of the vapor-liquid first-order phase transitions is introduced. For the modeling of the vapor-liquid phase transition a versatile ODE-based hysteresis model is implemented under the assumption of a local non-equilibrium condition that enables a certain level of supersaturation without phase change. The proposed modeling approach improves the existing equation-of-state type diffuse interface methods involved in homogeneous two phase flow models.