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Abstract

In the shipbuilding industry, it is difficult to create CAD models of existing or prototype parts, especially with many freeform surfaces. The paper presents the creation of the CAD 3D model of a shipbuilding component with the application of the reverse engineering technology. Based on the data obtained from the digitization process, the component is reconstructed in point cloud processing programs and the CAD model is created. Finally, the accuracy of the digital model is estimated.

Abstract

In the paper, a back swept impeller of centrifugal compressor is experimentally studied and numerically validated and modified to increase its pressure ratio and improve efficiency, as well as to analyse the effect of splitter blade location between two main blades. The back swept multi splitter blade impeller was designed with a big splitter positioned close to the main blade suction surface and a smaller splitter close to the pressure surface. Adding this multi splitter improves the overall performance of the modified impeller due to less intensive flow separation and smaller pressure loss. In particular, the total pressure ratio was observed to increase from 4.1 to 4.4, with one percent increase in efficiency.

Abstract

This article examines in detail the characteristics of Dien Bien earthquake on 19 February 2001 and its aftershocks. On the basis of the temporal development of aftershocks and the spatial distribution of tectonic faults, five aftershock series have been determined. The analysis of spatial distribution and temporal evolution of these five aftershock series has clarified the development in the source zone of Dien Bien earthquake, which is closely related to the active and recent activities of tectonic faults in the area, especially Lai Chau Dien Bien fault. The comparison between characteristics of aftershock activities of Dien Bien earthquake and geomorphological features as well as tectonic activities in the area has indicated that the magnitude of these aftershocks and their temporal evolution (early or late) depend not only on the closer or further distance compared to the mainshock and the active faults that cause them but also on terrain elevation, slope index, lineament density and their positions relative to other tectonic faults in the studied area.

Abstract

The aim of the study was to test the suitability of the 6th edition of Polish Soil Classification (SGP6) in reflecting the typical features of subalpine Bieszczady Mts. soils in comparison with the 5th edition of Polish Soil Classification (SGP5) and the newest version of World Reference Base for Soil Resources (WRB). Five soil profiles located in differentiated in terms of the parent material, topography and vegetation conditions of the natural environment were investigated. On the basis of described morphology and determined properties soils were classified according to different soil classifications. All soils under study were featured by presence of thick A horizons and high content of soil organic carbon accumulated even very deep in the profiles. Some of the mineral topsoil layers were classified as umbric/umbrik horizons. Moreover cambic/kambik horizons were present and in some cases also weak redoximorphic features occurred. The SGP6 enabled to distinguish soils with a thick, organic carbon-rich A horizons as umbrisols, a newly created subtype of grey soils. Furthermore, the soil taxonomic position according to SGP6 was more detailed in relation to the soil trophic status (in case of brown soils) and occurrence of weak redoximorphic features. That was reflected in number of subtypes to which analyzed soils were classified – 4 in SGP6 vs 2 in SGP5.

Abstract

Land use changes are local phenomena with global impact. They have an impact in a cumulative sense on biodiversity or soil degradation. This study aimed to examine the effects of different land-uses (arable land, permanent grasslands, abandoned grasslands, forest land) on the selected biotic and abiotic soil parameters in the Slovak mountain study sites Liptovská Teplička and Tajov. Biotic (microbial community structure, earthworm number and fresh body biomass, arthropod number and fresh body biomass), and abiotic chemical soil parameters (pH, total organic carbon, total nitrogen, nutrients) were measured. According to MALDI-TOF (Matrix Assisted Laser Desorption Ionization-Time of Flight), several bacterial strains were identified. Mutual relations between soil microorganisms and soil biotic and abiotic properties determined by different land uses were analysed. Microbial response expressed as average well-colour development (AWCD) values indicated relations between higher microbial diversity and higher nutrient availability at both study sites. In the comparison of land use types, permanent grasslands (PG) showed the lowest microbial activity in the depth of 0–0.1 m. But in the depth of 0.2-0.3 m in PG of both study sites, the higher microbial activity was recorded compared to the depth of 0-0.1 m. In addition, lower AWCD values in PG were in line with the lower available P and K content but higher earthworm density and biomass.

Abstract

In this study, we compare the pathological mitosis rates, chromosomal abnormalities and nucleolar organizer activity in Pinus pallasiana D. Don seedlings from natural population in the Crimean Mountains and from the urban plantations in the steppe of Ukraine. On the stages of anaphase and telophase of mitosis, such chromosomal abnormalities as bridges were most often found in the seeds of plantations exposed to air pollutants, whereas lead and agglutination of chromosomes were found in seeds from iron ore dump stands. Our studies have shown that P. pallasiana can be used for genotoxic monitoring of technogenic polluted lands.

Abstract

It is clear that the advantages of fibre glass-reinforced plastics surpass those of steel, but the failure analysis of composite structures is much more complex than that of isotropic materials as composite materials may fail in a variety of ways. In order to simulate the damage and fracture of bolted joints of fibre reinforced composite, the bond-based peridynamic method suitable for elastic, brittle and anisotropic characteristics of composite material is used. The peridynamic model for composite laminate is validated by the finite element method. Then a peridynamic program of composite damage is applied to calculating the damage of bolted joint structure and the damage propagation process and failure mode of the structure is obtained.

Abstract

The article presents the results of the research conducted within the framework of the project entitled WIND-TU-PLA (ERA-NET, MARTEC II), the general aim of which was to design and analyse supporting structures for wind turbines intended for operation on the South Baltic area. The research part described in the article aimed at developing a preliminary design for a jack-up platform which can operate on water areas with depth of 40 m. The main task was to determine optimal dimensions of platform legs and the radius of their spacing. Two jack-up platform concepts differing by spacing radius and hull dimensions were designed with the intention to be used as a supporting structure for a 6-MW offshore wind turbine. For each concept, the parametric analysis was performed to determine optimal dimensions of platform legs (diameter Dleg and plating thickness tleg). Relevant calculations were performed to assess the movements of the platform with parameters given in Table 1 in conditions simulating the action of the most violent storm in recent 50 years. The obtained results, having the form of amplitudes of selected physical quantities, are shown in comprehensive charts in Fig. 6 and 7. Based on the critical stress values (corresponding to the yield stress), the area was defined in which the impact strength conditions are satisfied (Fig. 14).

Then, the fatigue strength analysis was performed for two selected critical leg nodes (Fig. 12). Its results were used for defining the acceptable area with respect to structure’s fatigue (Fig. 14). Geometric parameters were determined which meet the adopted criteria, Table 6. The decisive criterion turned out to be the fatigue strength criterion, while the yield point criterion appeared to be an inactive constraint.

Abstract

Soil quality (SQ) dynamics assessment vis-à-vis land use/land cover (LULC) and elevation variations in Ethiopia is desirable as elevation impact on land use is highly pronounced. This study examined SQ indicators dynamics across LULC and elevation variations. For this, surface soil samples (0−20 cm) were collected from the recognized LULC categories of different elevations in Wanka watershed, northwestern Ethiopian highlands. Both disturbed and undisturbed soil samples that were taken from three adjacent LULC (natural forest, grazing and cultivated lands) and elevation (2238–2300, 2400–2600, and 2700–2800) classes analysed for the selected physico-chemical SQ indicators. Two-way ANOVA, Tukey’s multiple comparison test and SQ deterioration index were computed. The impact of LULC and elevation was found significant on key SQ indicators. In cultivated and grazing lands, soil organic matter (SOM) and soil nutrients like total nitrogen declined significantly (p < 0.01). Conversely, bulk density increased significantly (p < 0.01). The divalent basic cations (Ca2+ and Mg2+), cation exchange capacity and pH significantly (p < 0.01) decreased in upper elevation. Synergetic effect of LULC and elevation variations was found significant (p < 0.01) on SOM, total nitrogen, available phosphorus, water content at field capacity and soil particle distribution (silt and clay). Thus, elevation specific land management strategies that improve these SQ indicators need to be emphasized.

Abstract

In recent years, there has been a significant development in “green” and energy efficient propulsion systems, which fits into the general trend of environmentally friendly “green shipping”.

The pursued goal is to construct a safe passenger ship that is low in energy demand and equipped with a highly energy efficient, emission-free propulsion system.

The paper presents main problems encountered by designers of a small, hybrid-powered ferry powered lithium batteries. The conducted research allowed to create a design of an energy efficient hull shape, which decreases the demand for energy. Completed remote control model tests resulted in a proposal of an energy efficient and safe propulsion system with good manoeuvring capabilities. Measurements completed on an existing ferry permitted completing energy balance and forming an energy management policy.

The paper contains the emission calculations computed for the existing ferry that are necessary for the environmental impact analysis.

The soon to be constructed, newly designed vessel will provide a valuable contribution to hybrid-propulsion, energy management and unmanned technologies research.