Eva Kadlecova

Measurement of weakly magnetic material using new MR technique

Materials with different magnetic susceptibility can cause deformation of magnetic field in MR tomograph, resulting in errors in obtained image. Using simulation and experimental verification we can solve the effect of changes in homogeneity of static magnetic fields caused by specimen made from magnetic material in MR tomograph. This paper describes theoretical base and experimental measurement of new magnetic resonance imaging method for susceptibility measurement. This technique is suitable for substances with no signal in MR tomography. The method uses deformation of magnetic induction field in specimen vicinity. For MR purposes it is necessary to immerse specimen into reference medium with measurable MR signal (water is suitable).

Numerical Modeling of the Special Light Source with Novel R-FEM Method

This paper presents information about new directions in the modelling of lighting systems, and an overview of methods for the modelling of lighting systems. The novel R-FEM method is described, which is a combination of the Radiosity method and the Finite Elements Method (FEM). The paper contains modelling results and their verification by experimental measurements and by the Matlab simulation for this R-FEM method.

Numerical Model of Optimization of the Lead-acid Accumulator Grids

This article deals with chemical processes during charging and discharging of the lead-acid accumulator. There is presented one shape of electrode grids in this work, but we researched more variants. We prepared numerical models based on the combined flnite element method (FEM) and flnite volume method (FVM) of those variants and computed current density distribution on the surface of electrodes. The model joins magnetic, electric and current flelds, ∞ow fleld and chemical nonlinear ion model. Results were obtained by means of the FEM/FVM as a main application in ANSYS software.

Numerical Modeling of Accuracy of Air Ion Field Measurement

An analysis of the electric state of air shows the presence of various ion sorts. The therapeutic effect of negative high-mobility ions of proper concentration is known. This positive effect was observed in caves that are used for speleotherapy. This article presents the capability of gerdien tube measurement methods for measuring ion concentration and present results obtained by the design of new type of gerdien tube.

The source of light with high power LED diodes

This paper presents information about design of light sources. The special light source was designed and constructed for the research activity on the lichen structure in the Antarctica. This research is made by the Institute of Experimental Biology, Masaryk University, Faculty of Science. Required properties were continuous spectral characteristic with respect to photosynthetically active wavelength area, possibility of luminous flux regulation and practically zero thermal effect to illuminated object. Owing to new high-performance LED this type of light source was selected. Design of light source consisting of high efficient white LEDs, as well as experimental results, are presented.

The Optimal Design of the LVDS Bus with High EMS

The article deals with results which were obtained during the process of designing the LVDS (low voltage difierential signal) bus. This bus is very resistant to interference from the environment and to spurious emission of electromagnetic waves. According to the concrete requirements we prepared a design of the LVDS by means of numerical methods. The design was realized and its parameters verifled experimentally. The basic parameter of bus is its impedance Z = 100›, up to frequency f1 = 100MHz of the flrst harmonic of rectangle signal. DOI: 10.2529/PIERS060901103255