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Abstract

The purpose of the paper was the description of classification of chernozems applied in agriculture, the agricultural suitability of these soils, as well as processes contributing to their degradation. The study showed that the principles of chernozems classification into subtypes and varieties have not changed significantly since the introduction of the bonitation classification and legend of the soil-agricultural map. Lower-order units in chernozems type include typical and degraded chernozems considering deluvial varieties for both units. Chernozems are one of the most fertile soils in Poland, mostly classified from I to III bonitation classes and 1, 2 and 8 of the soil suitability complex. They constitute only 0.8% of the total area of the country, and their largest areas are located in : Opolskie, Świętokrzyskie and Lubelskie Voivodeships. Intensive agricultural use causes that chernozems are subject to progressive degradation mainly due to plaugh and water erosion as well as acidification of the crop layer.

Abstract

With the rapid development of the marine economy and continuous improvement of the industry, the scale of the offshore engineering is increasing. This raises interest in studying, theoretically and experimentally, gripping and bearing mechanisms for large-scale holding and lifting tools used in foundation pile installations. In this paper, the embedded gripping mechanism is studied based on the theory of elastic-plastic mechanics. The embedded and bearing performance of the tooth is simulated and the influence factors are studied. In addition, the device used in the simplified embedded experiment on the tooth of the embedded block is designed. The relationship between embedded depth, load, and tooth profile angle is identified and validated. Meanwhile, the embedded performance of linear and ring type teeth is compared experimentally in order to select the suitable type of tooth for various situations. This comparison makes the basis for designing an upending gripper for the marine pile foundation, which can realize the operation of holding the pile to prevent its falling.

Abstract

Full-film hydrodynamic lubrication of marine propulsion shafting journal bearings in running condition is discussed. Considerable computational difficulties in non-linear determining the quasi-static equilibrium of the shafting are highlighted. To overcome this problem the approach using two optimization methods (the particle swarm method and the interior point method) in combination with the specially developed relaxation technique is proposed. The developed algorithm allows to calculate marine propulsion shafting bending with taking into account lubrication in all journal bearings and exact form of journal inside bearings, compared to results of most of the publications which consider lubrication only in the aft most stern tube bearing and assume rest of bearings to be represented by points. The calculation results of typical shafting design with four bearings are provided. The significance of taking into account lubrication in all bearings is shown, specifically more exact values of bearings’ reactions, shafting deflections, minimum film thickness and maximum hydrodynamic pressure in the stern tube bearing in case of considering lubrication in all bearings.

Abstract

The paper considers the issue of thermo-chemical recovery of engine’s waste heat and its further use for steam conversion of the associated gas for oil and gas floating units. The characteristics of the associated gas are presented, and problems of its application in dual-fuel medium-speed internal combustion engines are discussed. Various variants of combined diesel-gas turbine power plant with thermo-chemical heat recovery are analyzed. The heat of the gas turbine engine exhaust gas is utilized in a thermo-chemical reactor and a steam generator. The engines operate on synthesis gas, which is obtained as a result of steam conversion of the associated gas. Criteria for evaluating the effectiveness of the developed schemes are proposed. The results of mathematical modeling of processes in a 14.1 MW diesel-gas turbine power plant with waste heat recovery are presented. The effect of the steam/associated gas ratio on the efficiency criteria is analyzed. The obtained results indicate relatively high effectiveness of the scheme with separate high and low pressure thermo-chemical reactors for producing fuel gas for both gas turbine and internal combustion engines. The calculated efficiency of such a power plant for considered input parameters is 45.6%.

Abstract

The possibilities of using concrete piles in a polymer composite reinforced with glass fibres in offshore facilities were shown. Laboratory tests of CFGFRPT type piles compressed axially and in eccentric compression for the analysis of CFGFRPT piles were used. Methods of analysis of dynamic systems for mathematical modelling of the displacement of the hammer in the pile driving process were applied. The possibilities of combining CFGFRPT piles, including the creation of hybrid piles were also presented. For example, concrete piles can be combined with concrete piles in a polymer composite reinforced with glass fibres with different fibre beam angles. The possibilities of using such hybrid piles in offshore facilities were indicated.

Abstract

The Soil Science Society of Poland has elected chernozem to be the Soil of the Year 2019. Although chernozems cover less than 2% of Poland, they have high importance for agriculture due to their productivity and play a specific scientific role for understanding of soil development and functioning in an environment. Chernozems are also crucial for the reconstruction of Neolithic agriculture development and human impacts on soil and landscape. This introductory paper presents (a) a specific definition of chernozem in Poland, connected with a separate distinction of black earths and colluvial chernozemic soils; (b) a review of the present and former classification schemes for chernozems in Poland and their correlation with international soil classification systems (WRB and Soil Taxonomy); (c) the spatial distribution of chernozems in Poland, their agricultural evaluation and threats for chernozems’ quality and future existence related to intense land use.

Abstract

The purpose of the work was to characterize the variously used humus in the south-eastern part of the Lublin region. The basic research material were data taken from the literature on the subject. Standard soil science methods were used in the study. The humus level of humus varieties ranged from 30 to 80 cm. The researched molds were formed from loess deposits, which most often showed graining of clay dust. Organic carbon content in humus levels did not exceed 2.9%. The surface levels of the analyzed molds showed clear decalcification. The CaCO3 content in the loess mother rock was a maximum of 15.5%. These are soils with high saturation of the sorption complex with basic cations. The content of available phosphorus and potassium in humus levels was low and medium. According to Systematics of Poland’s soils (2019), the analyzed molds mainly represented leached molds and typical molds, while according to the international soil classification WRB (IUSS Working Group WRB 2015) they are primarily Phaeozems. All the analyzed humus plants belong to soils with the highest utility value. Phenomena lowering the quality of molds in the Lublin region related to human activity are the use of improper agrotechnics, and above all water surface erosion. The unfavorable processes are favored by the undulating terrain and the grain size of the soils studied, characteristic for this area.

Abstract

The aim of the paper was to show the significance of chernozems for the Ukrainian economy, science and culture. The spatial distribution as well as variation of features of chernozems in Ukraine (including the uniqueness of these soils) was described. Also a brief history of investigation of Ukrainian chernozems was outlined. Particular emphasis was placed on the problems of degradation and protection of chernozems.