Eva Kroutilova

Inversion Reconstruction of Signals Measured by the NMR Techniques

The paper describes the magnetic resonance imaging method applicable mainly in MRI and MRS in vivo studies. There is discussed and solved the efiect of changes of magnetic flelds in MR tomography. This article deals with the reverse reconstruction results obtained from the numerical simulation of MR signals by various techniques, which will be usable for the experimental results veriflcation. Nuclear Magnet Resonance (NMR) is well known diagnostic non-destructive and non-invasive method (2{6). It is used to investigation of the materials properties. One of the often use of NMR is medical application (8,11). The magnetic resonance imaging (MRI) is used to the propel a ferromagnetic core. The concept was studied for future development of microdevices designed to perform minimally invasive interventions in remote sites accessible through the human cardiovascu- lar system. A mathematical model is described (3) taking into account various parameters such as the size of blood vessels, the velocities and viscous properties of blood, the magnetic properties of the materials, the characteristics of MRI gradient coils, as well as the ratio between the diameter of a spherical core and the diameter of the blood vessels. Other paper (4) present a MRI-compatible micromanipulator, which can be employed to provide medical and biological scientists with the ability to concurrently manipulate and observe micron-scale objects inside an MRI gantry. The micromanipulator formed a two-flnger micro hand, and it could handle a micron-scale object using a chopstick motion. The material engineering use the NMR too. For example NMR logging is an advanced method in formation evaluation and oil fleld production. It can provide the porosity, permeability, bound water volume, free ∞uid volume and oil viscosity. NMR logging is playing more and more important roles in oil and gas exploitation.

The Design of LVDS Bus with High EMC Compliance

The article deals with results which were obtained during the design of LVDS (low voltage differential signaling) bus. This bus is very resistant to interference from the environment and to spurious emission of electromagnetic fields. According to requirements we prepared designs of LVDS by means of numerical methods. The design was realized and its parameters verified experimentally. The basic parameter of bus impedance Z = 100 Omega, frequency f1 = 100 MHz of the first harmonic of rectangle signal.

Numerical Model of Optimization Lead-Acid Accumulator Grids

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

Experiments of Accuracy Air Ion Field Measurement

This article presents the capability of methods for measuring of the air ion concentration and principles of ion spectral analysis methods. The 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.

The Back Reconstruction of Signals by the NMR Techniques

This article deals with the reverse reconstruction results obtained from the numerical simulation of MR signals by various techniques, which will be usable for the experimental results verification. We solved the effect of changes of magnetic fields in MR tomography. The paper will describe the magnetic resonance imaging method applicable mainly in MRI and MRS in vivo studies.

The Effect of Non-homogeneous Parts into Materials

This article deals with the verification of experimental results obtained by numerical simulation. We solved the effect of changes in the homogeneity of magnetic fields evoked by different samples from conductive and/or magnetic materials and the different types of inhomogeneity in the MR tomograph. Moreover, the paper will describe the suitable magnetic resonance techniques. 1. ANALYSIS OF THE TASK The numerical modelling was realized using the finite element method together with the Ansys system. As the boundary condition, there was set the scalar magnetic potential φm by solving Laplace’s equation ∆φm = divμ (−gradφm) = 0 (1) together with the Dirichlet boundary condition φm = konst. on the areas Γ1 a Γ2 (2) and the Neumann boundary condition un · gradφm = 0 on the areas Γ3 a Γ4. (3) The continuity of tangential elements of the magnetic field intensity on the interface of the sample region is formulated by the expression un × gradφm = 0 (4) The description of the quasi-stationary model MKP is based on the reduced Maxwell’s equations rotH = J (5) divB = 0 (6) where H is the magnetic field intensity vector, B is the magnetic field induction vector, J is the current density vector. For the case of the static magnetic irrotational field, the Equation (5) is reduced to the Expression (7). rotH = 0 (7) Material relations are represented by the equation B = μ0μrH (8) where μ0 is the permeability of vacuum, μr(B) is the relative permeability of ferromagnetic material. The closed area Ω, which will be applied for solving the Equations (6) and (7), is divided into the region of the sample Ω1 and the region of the medium Ω2. For these, there holds Ω = Ω1 ∪Ω2. For the magnetic field intensity H in area there holds the relation (7). The magnetic field distribution from the winding is expressed with the help of the Biot-Savart law, which is formulated as