Improving the Quality of Magnetic Signature Reproduction by Increasing Flexibility of Multi-Dipole Model Structure and Enriching Measurement Information

J. Tarnawski , A. Cichocki, T. Rutkowski , K. Buszman, M. Wołoszyn IEEE Access – 2020
The paper presents the construction of a multi-dipole model that allows reproducing magneticsignatures of ferromagnetic objects. The virtual object used in the paper is an ellipsoid, which is the sourceof synthetic data. To make the situation more realistic, noise is added to the synthetic data. Two significantimprovements compared to previous work are presented. Three-axial magnetometers are introduced insteadof uniaxial magnetometers. However, a more important change is the modification of the model structurethat allows placing dipoles on the entire plane, e.g. object’s deck. The multi-dipole model consists of ana priori assumed number of permanent and induced single-dipole models. Each single dipole is described bythree magnetic moments and, depending on the applied approach, one or two dipole position parameters. Thenon-linear least-squares optimization method is used to determine model parameters. To assess the qualityof magnetic signature reproduction, qualitative and quantitative forms are used. The final quality assessmentis based on differences between the reference fields and the fields determined from the multi-dipole model.The applied modifications bring significant improvement, however, only their combined application allowsto restore magnetic signatures with good quality for directions other than for which the data were available.

Modelowanie bezpiecznika rozłącznikowego w układach formowania impulsów wielkiej mocy

Problem modelowania bezpieczników o dużej dynamice wyłączania prądu jest zagadnieniem szeroko opisywanym w literaturze. Układy takie mogą być wykorzystane w szczególności do formowania impulsów wysokiego napięcia o wartościach rzędu setek kV, charakteryzujących się czasem trwania rzędu ułamka μs. W niniejszej pracy przedstawiono empiryczny model bezpiecznika wielotopikowego, rozszerzony w oparciu o wyniki badań eksperymentalnych.

Analiza rezonansowego układu emisji impulsów pola elektromagnetycznego

W literaturze przedmiotu są opisane właściwości emiterów impulsów pola elektromagnetycznego w postaci układów bazujących na antenach wysokonapięciowych HVR (ang. High Voltage Radiator) [2, 5]. W celu podniesienia skuteczności emisji poprzez wydłużenie czasu trwania impulsu oraz zwiększenie jego amplitudy możliwe jest zastosowanie systemów rezonansowych dostrojonych do parametrów sygnału kształtowanego w układzie formowania impulsu wysokiego napięcia [2, 3]. W pracy dokonano syntezy modelu symulacyjnego systemu emisji impulsów pola elektromagnetycznego dużej mocy oraz zweryfikowano jego skuteczność w ramach badań eksperymentalnych przeprowadzonych na układzie fizycznym.

Application of method of differential magnetometric system for detection of sunken objects

This paper presents a magnetometric system with scalar sensors mounted on two independent platforms, which is used to detect sunken shipwrecks. Increasing the distance between the sensors allows for more precise measurement of the difference in the magnetic induction module than in the case of sensors mounted e.g. on the aeroplane’s wings. This type of system makes it possible to enlarge detection range of the sunken wrecks.

Comparison of properties of the new electro-mechanical model and circumferential model of the inductive-dynamic drive

The article presents a new electromechanical model of inductive-dynamic drive. The model is implemented in two environments: Maxwell for analyzing electrodynamic phenomena including moving of the disc and Ansys which allows for stress analysis on the basis of the volume forces imported from Maxwell. Additionally, a model validation by comparing with the existing circumferential model was carried out.

Optymalizacja parametrów obciążenia generatora magnetokumulacyjnego

W pracy przedstawiono wyniki symulacji komputerowej generatora magnetokumulacyjnego (GM) obciążonego cewką indukcyjną. Badania symulacyjne przeprowadzono w celu optymalizacji parametrów cewki obciążenia generatora dla wybranej konstrukcji modelu GM. Badano wpływ indukcyjność i rezystancji obciążenia na współczynnik wzmocnienia prądu w układzie oraz na energię pola magnetycznego zgromadzoną w obciążeniu.

Ship’s de-perming process using coils lying on seabed

A ship built from ferromagnetic steel disturbs the uniformity of the Earth’s magnetic field. Changes of ship’s signature are due to the magneto-mechanical interaction of the hull with the Earth’s magnetic field. The ship’s magnetic field can be detected by a magnetic naval mine. For this reason, the vessel has to be demagnetized. There are several methods of ship’s de-perming. The results of experimental and computer simulations of the ship’s de-perming process using coils lying on the seabed are presented in this paper. The simulation of the de-perming process with a hysteresis model of ship’s steel was carried out in Opera3d 18R2. The laboratory experiments were carried out using a physical ship’s model, several Helmholtz coils, magneto-resistive sensors, etc. The experiments and computer simulations have shown that ship’s de-perming with coils lying on the seabed is possi

Study of the effect of adiabatic heating on the operation of the electrodynamic actuator

Electrodynamic actuators are used in hybrid switching systems where a very quick contact separation as well as operation repeatability and long-term reliability are required. The article presents selected results of thermal studies in the electrodynamic drive system. Study was carried out on the basis of the 3D electromagneto-thermal model implemented in the Ansys_Maxwell environment. The present model allows to determine the critical parameters related to the heating and to guarantee the correct and repeatable operation of the actuator.

The flux compression generator load parameters selection

Computer simulation results of the flux compression generator (FCG) loaded with an inductor has been presented in this paper. Simulation research has been performed in order to select the parameters of FCG load coil properly. The influence of the load inductance and resistance on the current gain factor and the magnetic field energy accumulated in a load coil has been investigated.

Time domain model of the resonance-based electromagnetic pulses emission system

In the literature, the emission properties of the electromagnetic field pulse systems based on high voltage antennas (HVR) have been widely described. In order to increase the emission efficiency by extending duration and increasing amplitude of the impulse it is possible to use a resonance system tuned to the parameters of the signal shaped in the pulse forming circuit. The synthesis of a time-domain simulation model of a complex electromagnetic pulses emission system and its verification by experimental research has been presented in this paper.