Results 1 - 10 of 16
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[en] In this paper the possibility for geothermal energy use for electricity production is presented. The electric power is the most economical and ecological pure energy, which doesn't make any pollution of the environment. There are plenty of mineral thermal springs on the territory of Bulgaria. There are mineral waters with high temperature and under big pressure at the definite depth. (authors)
[en] According to their activity level, the radioactive wastes are categorized as high-, intermediate- and low-level waste. This report is mostly concentrated on high-level waste, which includes liquid waste from the first cycle of spent fuel reprocessing and solids into which such liquid waste has been converted. The disposal of the high-level radioactive waste consists of placing radioactive waste in a storage facility or repository, so that it is safe from unintentional disturbance in a manner which also prevents escape of any of the waste material for extremely long time periods. However it has shown to be the weakest point of the nuclear power. In this report, an overview is given of the most used materials for nuclear waste immobilization: glasses and ceramics, their properties, different types and a comparison between them. The radioactive waste is immobilized when it has reduced its potential for dispersion of contaminants in the environment and conversion of a waste into a wasteform by solidification (vitrification, cementation, bituminization) and embedding. Different types of glasses and ceramics are under development and further research. Keywords: disposal, radioactive waste, vitrification, cementation
[en] Results of investigation of the magnetic field effect on the resonance frequencies of structures, containing an YIG component and HTS Y1Ba2Cu3O7 electrodes of several configurations at 77 K and in the DC magnetic field up to 50 mT are presented. Some peculiarities of the obtained dependences are discussed
[en] Male rats Wistar breed were treated with insecticide Agria-1050 which contains methylnitrophos or thionphosphate (TP). The animals received treatment 5 days weekly during 4 months per os in a dose of 1/40 LD50 (15 mg/kg b.w.). On the 20th day Ce144 was introduced as CeCl2. The control group was composed of rats untreated with insecticide. On the 1st, 3rd, 8th and 15th day after application of Ce144 the activities or cytochrom P-450 (P-450), amino-pyrine-N-demethylase (APD) and aniline liver microsome fraction. As a result of the chronic treatment with Agria 1050 a decrease chronic treatment with Agria 1050 a decrease is found in the content of P-450, ADP and AH. The study of the restoration of the liver monooxigenase system after a low activity of compensatory mechanisms. Ce144 applied intratracheally caused changes, corresponding to a post-stress situation with their biphasic character, as well as with their amplitude: increased activity of P-450 and ADP on the first day, followed by a prolonged 144 and TP the radionuclide caused the character of the changes, whereas the insecticide only increased 4-5 times the amplitudes of these changes. The most pronounced was the increase of AH after the combined action of Ce144 and TP. (authors)
[en] In this work, we report investigations on the adding of K2CO3 in a wide concentration range in the initial batch of YBCO system and the influence on the electrical and magnetic properties and microstructure. (orig.)
[en] The attractive idea to create artificial superconductor/ferromagnet heterostructures (SC/FM) for easy control of the superconductor properties by magnetic field is widely considered last decade. Of a special interest for applications are the HTSC/FM heterostructures, particularly the YBCO/LSMO, where the magnetization value of LSMO could be adjusted by doping, by variation of oxygen content, and magnetic domain structure could be controlled by reasonable magnetic field. We concentrate on the in-plane field penetration into the YBCO/LSMO hybrid film, which is of practical interest as the in-plane field easier saturates the magnetic film. The study is performed by the magneto-optic visualization technique at T down to 7 K. We found a striking transformation of the in-plane external field into a wave of alternating perpendicular flux, the particular features of which depended on the temperature and magnetic prehistory at temperature above superconducting transition. To shed light on the mechanism of the effect, we have investigated the magnetic domain pattern of manganite film and it's transformations due to variation of temperature and the field. The results are discussed taking into account the finite size of the hybrid structure and the magnetostatic field distribution.
[en] This paper deals with a theoretical treatment of the problem of the interaction between the magnetic field of a small dimension coil and the superconducting film, which has become partly resistive after the induced current density had exceeded the critical value Jc. (orig.)
[en] Formulae for calculating the resonance frequency and the microwave (MW) losses in HTS thin film coplanar waveguide resonators containing a tangentially magnetized ferrite layer were obtained using the perturbation method. The problem of achievement of a maximum sensitivity of the resonance frequency to the field intensity and the problem of reducing the MW losses contributed to the resonator by the magnetostatic waves were analysed. (author)
[en] The influence of Rb2Co3 additive on the properties of YBCO was investigated. The impurity was added to the usual stoichiometry of Y1Ba2Cu3Oy to produce an initial batch with general formula Y1Ba2Cu3(Rb)xOy where x = 0 to 0.60. Only traces of (2.21 x 10-2 wt.%) Rb were found in all samples after final baking. Adding Rb shifted the temperature Ton of the ''magnetic transition'' towards lower temperatures without affecting the electrical HTSC characteristics and improved the grain size homogeneity
[en] Kinetics of magnetization reversal and dynamics of domain walls in thin La0:7Sr0:3MnO3 manganite films are studied by magnetooptic visualization technique. Two types of magnetic domain structure are revealed in 20 nm thin film, namely, the small-scale patched domains with perpendicular magnetization, which are formed after zero field cooling, and wide macro-domains with an in-plane magnetization, which appear as a remnant state after saturation by the field of any orientation. The following magnetization reversal is found to occur via the nucleation and thermoactivated motion of the 1800 domain walls. Strong temperature dependence of dynamic parameters is established near the room temperature. A heating of 10 K above 294 K results in 1.5 reduction of coercivity, in alteration of magnetic permeability, magnetic viscosity and activation volume by order of magnitude. The obtained results could be explained taking into account magnetic after-effects specific for materials with the magnetic ions of transient valence.