[en] The role of the sterile neutrinos to the r-process nucleosynthesis in supernova explosion is studied. Previously it has been argued that a large part of neutrino mixing can be excluded if the supernovae are the origin of the heavy elements. It is shown that a conversion to sterile neutrinos may evade those limits. the possibility that such conversions can enhance the nucleosynthesis is investigated. The desired mass spectrum is consistent with neutrino masses suggested by other observed phenomena, like the solar neutrino problem, the atmospheric neutrino problem, dark matter and the LSND signals. (author). 8 refs

[en] The low-temperature ashes bound approximately twice as much SO₂ as the high-temperature cyclone ash. It confirmed the advantage of circulated fluidized bed technology, compared to pulverised firing technology in binding sulfur compounds. Considering the high SO₂ binding ability of low-temperature ash and the absence of sulfide sulfur in it, the circulated fluidized bed combustion technique might prove to be one of the most environmentally harmless techniques applicable in the future energy production in Estonia

[en] At present, much attention has been paid to the environmental protection in the world. In this work, the characteristics of NO_x emission in fluidized bed oil shale combustion were investigated experimentally and theoretically. The results obtained from this study will provide important information for controlling NO_x emission during the fluidized bed combustion of oil shale

[en] This research focuses on the dependence of laser deposited YBa₂Cu₃O₇, film properties on the depth of ablated target layers. The results demonstrate that the critical temperature T_c , the second phase, and the morphology of the films are sensitive to the conditions of the target. The effect of laser glazing of the target is considered. In the case of thin films, T_c enhancement of the films deposited from the glazed target were observed. (author)

[en] The mine able oil shale bed is located in horizontally lying Ordovician limestones at a depth of 10-60 meters from the ground surface. Limestones are covered with Quaternary sediments, mainly till and loam, sporadically seams of clay occur. The overburden rocks of oil shale bed are jointed limestones with weak contacts between layers. The upper part of limestones is weakened additionally due to weathering to depths of 10-20 metres. Ground movements caused by mining reach the ground surface easily due to the shallow location of workings. The size and nature of these movements depend on mining and roof control methods used. In this study the impact of geotechnical processes on the ground surface caused by four different mining methods is analysed. A new, artificial micro relief is formed on undermined areas, where the ground surface depressions are alternating with rising grounds. When the Quaternary cover contains loamy sediments, the surface (rain) water will accumulate in the depressions. The response of usable lands on undermined areas depends on the degree of changes in the relief and water regime. There exists a maximum degree (limit) of changes of ground movements in case of which the changes in land use are not yet considerable. The factor of land deterioration was developed for arable and forest lands taking into account the character and degree of negative impacts. When no one deterioration factor exceeds the limit, the value of arable land will be 1.0 (100%). When some factor exceeds the limit, then water logging in subsidence troughs will diminish the value to 0.7, slopes to 0.8 and the area of weathered basic rocks to 0.9. In case of a combined effect of all these factors the value of arable land will fall to 0.5. As the long-term character of ground movement after room and pillar mining is not yet established, the factor for quasi stable areas is taken preliminarily as 0.9. Using detailed plans of mined out areas and the proposed factors, it is possible to assess the value of usable lands there, and also to locate various objects on an undermined territory. (author)

[en] Oil shale mining production, inflation in Estonia, and oil and fuel market prices represent a series of interconnected links. Unfortunately, the last economic parameters could not be exactly predicted. In the present work stochastic methods of mathematical modelling are used to forecast Estonian oil shale economy in the future. (author)

[en] New algorithms are derived and the software composed for fast computing of the one-dimensional wave functions in the range of a continuous energy spectrum. The method can be applied to calculate the quantum-mechanical Franck-Condon factors and the fine structure of the optical spectra of simple quantum systems. This enables to improve the real potential energy curves of such systems, which is demonstrated for diatomic xenon molecules. (author)

[en] The symposium 'Environmental Impact and Water Management in a catchment area perspective' reviews the results of research conducted in the past period, based on the principle of complex use and protection of the water body. In addition to Finnish specialists, Swedish, Russian, Latvian, and Lithuanian specialists have participated in the studies

[en] Trichloroethylene (TCE) and vinyl chloride removal by pulsed corona discharge was investigated with attention to energy efficiency and byproduct identification. Approximately, 50 to 95 percent removal of TCE and vinyl chloride was observed depending on the energy density applied to the gas. Water vapor had no significant effect on TCE removal. Evidence was found for post-corona reactions leading to removal of vinyl chloride downstream of the plasma discharge. Energy efficiencies of 100-900 g/kw-hr in the case of 1000 ppm feed of TCE and efficiencies of 2-24 g/kw-hr for a 100 ppm feed of vinyl chloride were found. In TCE experiments, the formation of dichloroacetyl chloride was observed, while chloro-ethane formation was found for vinyl chloride. In both cases, Cl- was measured downstream of the pulsed corona reactor in a water trap using an ion-selective electrode, although measured amounts varied widely due to condensation in the gas lines between the reactor and the water trap. The addition of a platinum-rhodium coated electrode was found only to reduce the downstream removal of vinyl chloride at low energy density. (author)

[en] Kinetics of oxidation of oil shales of Goeynuek (kerogen type I) and Beypazari (kerogen type II) deposits was investigated under isothermal conditions using a fixed-bed reactor in various temperature modes. Combustion profiles were obtained using a continuous gas analyzer. Rate data were analyzed basing on the assumption that oxidation takes place on the surface of solid oil-shale particles and decomposition of kerogen is not significant. Oxidation rates were determined and constant overall-orders of reaction from the kinetic analysis within investigated heating rates were found. Effect of heating rates on reaching final isothermal temperatures was investigated, and kinetic parameters of the overall oxidation reaction for each heating rate determined. (author)