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65 Scientific Journals of the Maritime University of Szczecin, no. 65 / 2021



 

Recent Submissions

  • Ghadimi, Parviz; Nazemian, Amin; Karam, Saeid (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    The hydrodynamic performance of trimaran hulls has been previously investigated for optimum performance in calm water, but there is still a limited understanding of its motion response; therefore, a CFD-based numerical approach was developed and applied on a trimaran hull in the presence of regular and irregular waves. To validate the CFD method, a comparison was conducted using both experimental and 3D panel method data. In this study, two different turbulence models were surveyed, and the SST Menter k-Omega (k-ω) turbulence model was shown to be a more accurate model than the realizable k-Epsilon (k-ε) model. The different features of the proposed numerical model include the implementation of an overset mesh method, unique mesh plan refinement, and wave-damping region. The discrepancy between the experimental data and the results of other seakeeping calculation methods have always been problematic, especially for low-speed strip theory and 3D panel methods, but good consistency was observed between the proposed CFD model and experimental data. Unlike potential-based or conformal mapping seakeeping analysis methods, the effect of nonlinear waves, hull shape above the waterline, and other ship dynamic phenomena were considered in this CFD application. The proposed CFD method reduces the simulation time and computational efforts for ship motion calculations.
  • Dounar, Stanislau; Iakimovitch, Alexandre; Jakubowski, Andrzej (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    In this paper, a special configuration for the huge multipurpose machine tool of “travelling column” type was investigated by the finite element analysis. Internal degrees of freedom of a bulky system consisting of the ram, stock, column, sledge and bed, were implemented by the hydrostatic guides. A simulation of coupling two assembled columns into the portal structure was completed. The results of this work showed that temporal joining raises the spindle static rigidity by 1.39–1.91 times depending on the direction (mostly longitudinal – along the X-axis). The simulation also revealed the robustness of a whole-machine resonance pattern (11.7–39.0 Hz) to “column–to–portal coupling”. Eight types of eigenmodes were analyzed for frequency intervals from 0 to 80 Hz. A decrease by 2.9 times of the resonance peaks of a frequency response function was observed in the case of a portal structure creation. In case of columns-to-portal transition, stable cutting just at resonance frequencies (resonance overriding) becomes allowable. Overall, the “Portal” structure is recommended for intermittent cutting machining by raised high spindle unit at frequencies below 40 Hz.
  • Stępień, Julianna; Pilarska, Malwina (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    Presented are regulations concerning the operation of passenger ships (with particular emphasis on Polish ferries) designed to increase maritime safety the SOLAS Convention, established in 1974 and codified in 2002, codifies these regulations, and the International Maritime Organization mandates additional regulations, created in response to a rapidly increasing number of maritime disasters. The analyses described herein were based on restrictions established for the “Jan Śniadecki” and “Mikołaj Kopernik” ferries. Safety of ro-ro units, which also typically have a significant number of people on board, was also analyzed. Also included in the study were ship operational- limitation characteristics with respect to structure, unsinkability, and stability of machinery and electrical equipment, fire protection, operational requirements, and rescue measures and devices, along with their purpuroses. Safety management consists of taking appropriate actions to prevent or minimize the effects of an accident or a disaster and is assessed on the basis of calculations and experience gleaned from analogous cases. Safety management can proceed if a problem has been thoroughly assessed. The potential risk of negative consequences with respect to the safety of the transport process as a whole must be considered, and the safety of the whole must not be risked for that of a particular part of it. A safety management decision can be made when its necessity is not in doubt. A problem is assumed to have only one solution. The effectiveness of the previously used method should be carefully assessed before proceeding to the next method. Security management is not easy and requires much professional knowledge and experience.
  • Marcjan, Krzysztof; Kotkowska, Diana (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    Abstract This paper examines the factors affecting the performance of VTS operators. A general review of the human factor as a determinant of navigational safety is presented. The elementary nature of the system and its structure are defined, and the ability of a VTS operator to perform planned tasks within a specified timeframe and in a specific manner is analyzed. A reliability assessment scheme is proposed, which is based on the interpretation of factors affecting the VTS operator’s efficiency. The effective performance of VTS operators, along with the specific nature of the maritime environment and reliability of the vessel traffic management support, are key determinants in the process of ensuring the reliability and security of the entire system.
  • Boljat, Helena Ukić; Vilke, Siniša; Grubišić, Neven; Maglić, Livia (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    In Europe, at the end of the 20th century, the growth of marinas followed the rapid development of recreational marine activities. This trend has now slowed and today the creation of new marinas or the extension of existing marinas is less common, mainly due to the enforcement of protective environmental regulations. As the port sector is facing some major sustainability challenges, like tackling the pollution generated from port activities, the “green port”, or “green marina”, concept has now become a requirement. Both types of nautical ports, public ports and private marinas, share the same responsibility to achieve management standards. The term “green port” in practice describes the responsible behavior of all stakeholders in the port’s business, with a focus on the long-term vision towards the sustainable and climate-friendly development of the port’s infrastructure. This paper aims to confirm the adequacy of multi-criteria analysis (MCA) for the evaluation and introduction of energy efficient mobility options in nautical ports. Within the paper, a multi-criteria based model for energy- efficient mobility selection is presented. This model is tested on two Croatian private marinas and obtained results indicating the most suitable action for both. The output of the model showed that by far the best energy- efficient solution was the installation of electric charging stations (ECS) for cars. The presented model can assist decision-makers in port authorities and marina administrations in planning and finding the best scenario for the development of energy efficient systems and services.
  • Kuznetsov, Valerii; Gogorenko, Oleksiy; Kuznetsova, Svetlana (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    Charge air cooling is essential for the efficient operation of marine diesel engines. This work presents the results of research on the characteristics of long-range heat transfer surfaces for marine diesel engines. Elliptical and flat-oval tubes were considered. This study was carried out using mathematical models that consisted of the equations for energy conservation, motion, continuity, and state. The RSM turbulence model was used to close the system of equations. To solve the resulting system of equations, the RANS approach was used, which was implemented in the software package Code Saturne with a free license and the SimScale cloud service. The mathematical model was verified by comparing the model results with the experimental results obtained using a prototype heat-exchange surface of a charge air cooler at a test bench. The discrepancy between the theoretical and experimental heat transfer coefficient α was ≤ 8.3%. An estimate of the compactness of smooth elliptical and flat-oval tube banks compared with round ones was carried out. A 19.6% increase in compactness was obtained for elliptical tubes and 17.5% for flat-oval tubes. Based on the profiled finning surfaces, it is possible to improve their thermohydraulic characteristics by up to 40% when using them together with elliptical tubes compared with round ones and up to 26% when using them with flat-oval tubes.
  • Kacprzak, Paweł (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    This article presents an analysis of internal forces and roll motion during a nodule loading simulation for a ship at sea. The study carried out a full assessment of ship behavior during loading, which took into account wave height and period occurrence around the Clarion–Clipperton Zone by the use of an operational efficiency index. One of the aims was to verify whether waves have an influence on excessive ship motion and internal forces during nodule loading. Two alternative loading sequences were developed and compared by taking loading time, shear forces, bending moments, roll motion and waving into account. The research shows that loading is only possible during specific sea weather conditions for the selected bulk carrier.

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