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Search Results: 1 - 10 of 332290 matches for " Slavomír Horák "
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AFGHANISTAN TEN YEARS AFTER...
Slavomír Horák
Obrana a Strategie , 2011,
Abstract: The article focuses on the analysis of the internal politics of Afghanistan after 2001 and evaluates the results of state- and nation-building. The emphasis on internal politics is the only possible way to understand the processes in the country and work out the strategy for the country after the planned withdrawal (or limitation) of foreign troops from the country. In this context, the fragmentation and deepening cleavages among various social strata in the country (ethnic, sub-ethnic) is considered to be a crucial determinant of the development in the country. Several power groups define diverse attitudes towards the character of the future Afghan state. These circumstances could lead to the new round of the military conflict after the removal of foreign troops which are considered as a negative factor by a large part of the Afghan elite, albeit they serve as one of the stabilization factors in the country. However, the international community has (and will have) limited tools and influence to prevent any prospective conflict in the country.
Selected results of the slovak coal research
Turèániová ?udmila,Hredzák Slavomír
Acta Montanistica Slovaca , 1997,
Abstract: The contribution gives the review of Slovak brown coal research in the last 10 years. The state and development trends of the coal research in Slovakia from the point of view of the clean coal technologies application are described. Some selected results which have been obtained at the Institute of Geotechnics of the Slovak Academy of Sciences are also introduced.
New separators based on the action of centrifugal force fields and possibilities of their utilisation in coal preparation
Hredzák Slavomír,Jakabsky ?tefan,Lovás Michal
Acta Montanistica Slovaca , 2000,
Abstract: The contribution gives an attention to a new generation of equipment operating under action of high centrifugal forces. Their development was caused by a low efficiency of conventional mineral processing facilities as well as by the losses of valuable components in tailings at preparation of fine-grained raw materials. The first pilot plant experiments and tests under operating conditions confirmed the suitability of their design and enabled their introduction to the mineral processing and coal preparation plants as well as to the waste disposal.
Overview of the World′s Exploitation, Consumption and Resources of Coal
Hredzák Slavomír,Lovás Michal,Jakabsky ?tefan
Acta Montanistica Slovaca , 1998,
Abstract: The contribution gives attention to the general trends in the coal economy in the 90s. The most significant world′s coal producers are presented with regard to the total coal production as well as to the hard and brown coal production. The article also deals with the topical conditions in coal exploitation, consumption and resources in the world′s regions and countries. Some new trends in coal combustion and metallurgy are introduced.
Possibilities of power coal desulphurization from upper nitra basin by means of magnetic separation
Hredzák Slavomír,Lovás Michal,Jakabsky ?tefan
Acta Montanistica Slovaca , 1997,
Abstract: The paper deals with the application of magnetic separation in coal desulphurization. Specimens of power coal from Upper Nitra basin were subjected to breaking, grinding and wet high gradient magnetic separation under magnetic field induction of 1,7 T. Sulphidic sulphur contents and recoveries into separation products have been observed.
Application of the Matrix Model of Hydrocyclone in Coal Preparation
Hredzák Slavomír,Jakabsky ?tefan,Le?ko Michal
Acta Montanistica Slovaca , 1998,
Abstract: The paper describes mathematical model of the water only cyclone function on the basis Of experimental data. The experiments have been realized in a pilot plant cyclone. The model was verified in the case of steam coal preparation from the Cíge , Handlová and Nováky localities. The obtained results confirmed that the applied model is suitable for the design of cyclones parameters under the operating condition.
Influence of hydrocyclone underflow jet diameter on washing efficiency of steam coal from the Cige Colliery
Hredzák Slavomír,Jakabsky ?tefan,Lovás Michal
Acta Montanistica Slovaca , 2000,
Abstract: The contribution describes results of steam coal washing in water-only (WO) cyclone at various diameter of underflow jets. The overflow jet with the diameter of 68 mm was used. In the case of underflow the following jet were applied: 18 mm, 15.6 mm and 14.5 mm.Washing products were subjected to chemical, grain size and float-sink analyses. Mass yields of these products were also determined to compute the material balance of coal components. Conclusively, the partition curves have been constructed and cut points as well as errors probable and imperfections were determined. The Grumbrecht′s efficiency of preparation was also computed.Ash and total sulphur in dry matter were observed in washing products. The overflow product with the lowest content of ash i.e. 11.62 % was won at the underflow jet diameter of 18 mm, but also at the lowest yield and combustible matter recovery. The highest recovery of combustible matter was achieved at the diameter of 15.6 mm, however at the highest ash content..The grain size analysis resided in the sieving of overflow and underflow products into following classes: 0.5 mm, 0.5 1 mm, 1 2 mm, 2 3 mm and +3 mm. On the basis of mass yields the partition curves were constructed with the aim to determine a classifying effect. Only in the case of jet ratio 68/18 it was possible to determine basic characteristics: d50 = 2.2 mm, Ep = 1.74. It has to be mentioned that the coarser grain went to overflow and finer concentrated in underflow in all three cases. Hence, it is reverse situation as at a classical classifying hydrocyclone.The float-sink analyses were conducted at the following densities: 1.3, 1.4, 1.5, 1.7 and 1.8 gcm-3. According to obtained results, i.e. mass yields into density classes, the comparison of separation efficiency with regard to the grain size as well as to the ratio of overflow and underflow jets diameters has been also carried out.The best sharpness of separation was achieved at the underflow jet diameter of 18 mm. Summary parameters are as follows: Ep = 0.255 and W = 68.58 %. The both values are almost twice higher as in the case of other jet diameters. Also in this case the errors probable for all grain sizes are the lowest and the Grumbrecht′s efficiencies attain the highest values. As to grain size the best results were obtained for the class of 1-2 mm and 2-3 mm, respectively, at all tested diameters of underflow jet.The reduction of underflow jet diameter results in a low enhancement of mass yield into overflow as well as in the increasing of ash content and combustible matter recovery in this product.
The application of magnetic carriers in wastewater treatment
Jakabsky ?tefan,Lovás Michal,Hredzák Slavomír
Acta Montanistica Slovaca , 2000,
Abstract: Ferromagnetic fluid is a kind of polyphase liquid, which is a stable colloid system of sufficiently small mono-domain magnetic particles covered by a film of surfactant and dispersed in a base liquid. Ferrofluids can be prepared in various base liquids such as water, hydrocarbons, mercury, etc., according to them utilisation. The basic properties of ferrofluids, i.e. the high magnetic polarisation of saturation and zero remanence predestine their application in various industrial branches including mineral processing and wastewater treatment.Wastewater treatment by the application of ferrofluids under magnetic field resides in the action of the field on the ferrofluid added to the oil substance. Strongly magnetically polarisable fluids enable to increase the magnetic susceptibility of oil substances to suitable level for their removal from water by a magnetic way. It was observed that the oil drop with the weight of 3.10 -3g and the ferrofluid concentration of 3% starts to move in the direction of the magnetic intensity growth at the minimal value of 105 A.m-1. It means that ordinary permanent magnet with the magnetic induction of 0.1 T causes the movement of the oil drops with a relatively small admixture of ferrofluid on the water level. This knowledge is very important for the design of magnetic filtration device which will be able to separate oil substances from water.Modification of magnetic properties of weakly magnetic materials by ferrofluids was also carried out in the case of magnetic filtration of water contaminated by fine grains of copper concentrate created by chalcopyrite. After admixing the ferrofluid into the suspension the recovery of mineral to the magnetic filter product ranges from 75 % to 98 % depending on the kind of ferrofluid and pH values. It was observed that in the case of water-based ferrofluid the recovery decreases with the increasing of pH value. But, on the other hand the increasing of pH value under the application of kerosene-based ferrofluid results in the increasing recovery. According to the obtained recovery values, ferrofluids can be consider a good agent for the magnetic susceptibility modification.The magnetic sorbents consisting of magnetite seed covered by the film of K4Fe(CN)6 were applied in the treatment of water polluted by copper ions. The magnetic sorbent was added in the solution during intensive mixing in the amount of 25g per Litre of contaminated water. The Cu concentration of 48.2 μg.ml-1 decreased to the value of 3.7 μg.ml-1 after magnetic filtration.Generally, a method for separating particles of a
A combination of bioleaching and electromagnetic separation in the treatment of quartz sands
?tyriaková Iveta,Hredzák Slavomír,Lovás Michal
Acta Montanistica Slovaca , 2006,
Abstract: This contribution deals with the treatment of Slovakian eolic quartz sands by bioleaching and magnetic separation with the aim to remove iron. The X-ray study of sand patterns confirms that quartz occurs as a dominant mineral. Accompanying minerals are represented by smectite and feldspars. As to the sample of unground sand, bacterial leaching resulted in a Fe2O3 reduction to the content of 0.13 %. Similarly, in case of ground sample, the Fe2O3 content was decreased to the value of 0.19 %. Thus, biological leaching removed 60 % of Fe and by following leaching by oxalic acid total the iron removal was 70.5 %. Finally, the application of magnetic separation resulted in the total iron removal of 93 % and, in such combined way, the prepared product contained 0.024 % of Fe2O3. Achieved results on the iron removal points to the fact that the combination of leaching and magnetic separation enables to obtain a product usable in glass industry.
Communication model of emuStudio emulation platform
Peter Jakub?o,Slavomír ?imoňák,Norbert ádám
Computer Science , 2010,
Abstract: Within the paper a description of communication model of plug-in based emuStudio emulation platform is given. The platform mentioned above allows the emulation of whole computer systems, configurable to the level of its components, represented by the plug-in modules of the platform. Development tasks still are in progress at the home institution of the authors. Currently the platform is exploited for teaching purposes within subjects aimed at machine-oriented languages and computer architectures. Versatility of the platform, given by its plug-in based architecture is a big advantage, when used as a teaching support tool. The paper briefly describes the emuStudio platform at its introductory part and then the mechanisms of inter-module communication are described.
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