M. Cap

Comparison of methods for detecting the signal arrival time in TDOA localization method

This article presents a part of radiofrequency method, known as ultra-high frequency (UHF) method for detection and localization of partial discharges in high-voltage transformers. The UHF method is the most advancing method for this type of transformer diagnostic. The state of the art in instrument technology allows real-time acquisition and processing of pulsed broad band signals together with 3D localization of PD occurrence. The UHF method is based on measurements of electromagnetic waves in UHF spectrum produced by PD. Typical spectrum of the PD UHF signal ranges from hundreds of MHz to units of GHz. Spatial localization of the signal origin is based on Time Difference of Arrival (TDOA) algorithm. Accuracy of the TDOA is determined by accuracy of detecting of the signal arrival time on each measured channel. Verification of the detection algorithms function is done on real measured data from 500 MVA high-voltage transformer.

Analysis of magnetic properties measurement in closed samples

This paper contains an analysis of magnetic properties of a coil core material. Methods of demagnetizing the sample before measurement are discussed. Static and dynamic hysteresis loops, initial magnetization curve, and normal magnetization curve are measured. The authors show the corrections of systematic errors for all measurements and indicate the specific conditions under which the measurement of the characteristics is realized.

Electromagnetic waves and mental synchronization of humans in a large crowd

At present, the increasing number of terrorist activities has brought a focus on the problem of how to effectively maintain public order. A major challenge in this connection consists in analyzing and possibly innovating the set of existing crowd control procedures or instruments, which prominently includes non-lethal weapons (NLW) as a support tool to regulate human behavior during mass gatherings. The paper discusses the basic research into the impact of low-frequency electromagnetic fields on individuals interacting within a social group, and it proposes certain basic ideas and principles related to brain synchronization as the central precondition of crowd behavior. By extension, it was previously demonstrated in this context that changes of the above-specified electromagnetic fields can affect the physical and mental capabilities of a human being, and the related conclusions are reconsidered and further developed herein.

Diagnosing brain tumors with MRI

The present paper discusses the improvement of accuracy in overall diagnostics related to brain tumors. The proposed measures include, for example, maximizing the use of image modifications and decreasing the radiation doses received by a patients body. The wider project is centered on the diagnostics of pathological tissues in the brain; it describes and compares the classification and identification of particular brain tumors.

RF magnetic field enhancement in MRI by metamaterial structures

The paper is focused on the design, numerical simulation and properties measurement of planar resonant structures. The potential of the structure consists in its utilization in magnetic resonance imaging since it allows significantly increase the magnitude of radiofrequency magnetic field. The developed four-conductive-layer structure is termed as Grid Quasi Periodic Resonant structure. Measured results have shown the GQPR structure provides homogeneous magnetic field in its vicinity.

The statistical evaluation of MRI data of a plant tissue

The authors present a statistical evaluation of the MRI images of a plant tissue. Therefore, we compare the commonly used MRI contrast and looking for the best contrast to evaluation of MRI data of a plant tissue. The acquired images are classified in terms of the signal-to-noise ratio, intensity difference and steepness of the edges. We focused on the manual evaluation of the statistical data in the area of the plant tissue.

Numerical analysis of metallic periodic structures in THz region

The article presents results of numerical modelling of planar resonators arrays deigned for THz frequencies. The increase in the resonant frequency of each arrays element is achieved by down-scalling its dimensions. Accompanying effects, as the rise of resistive metal losses are examined also. The presented results have shown the possibilities of down-scalling the geometry of basic planar resonators in order to achieve the resonance phenomena at THz frequencies, eventually in the infrared band.