English Polish
Akademia Morska w Szczecinie

DSpace Home

DSpace/Manakin Repository

Browsing by Title:

  • Ganjgani, Arman Aghaei; Ghassemi, Hassan; Ghiasi, Mahmoud (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    This paper investigates the effect of buoys and a clump weight on the mooring lines and the dynamic response of the floating platform. The full-scale of the OC4-DeepCwind semisubmersible FOWT platform is analyzed using the boundary element method (BEM) with ANSYS-AQWA software, when considering regular wave conditions. Platform motions and mooring line tension in the surge, heave, and pitch are presented and discussed in the time domain analyses (TDA) and frequency domain analyses (FDA). Validation is performed by compression of the platform motion RAO and the fairlead tension RAO magnitudes in the surge, heave, and pitch (for both numerical and experimental data) under seven sea states’ regular waves. The results show that increasing the number of buoys at a constant volume decreases the surge and pitch motion amplitude, while the heave motion increases slightly. Adding the buoy and clump weight (type 1) to the mooring line reduces the oscillation amplitude tension. In addition, raising the number of buoys increases the oscillation tension.
  • Falkowski-Gilski, Przemysław; Uhl, Tadeus (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    Thanks to the availability of mobile devices and the spread of broadband access around the world, the number of network users continues to grow. This has raised user awareness when it comes to the quality of content they consume. Many service providers and operators focus on monitoring QoN (Quality of Network) and QoS (Quality of Service) parameters, particularly those influenced by bandwidth and latency. However, for most end-users, quality is understood as the subjective QoE (Quality of Experience), a mixture of several individual factors. This paper presents a QoN evaluation, carried out under real-time operating conditions at a university campus, considering the overall performance of the cellular network. The study involved 50 mobile devices, i.e., smartphones, used by students during their typical activity throughout a week. The results were gathered on the eve of 5G, using a custom-built Android application. This application enabled the acquisition of valuable data about the wireless link, including download and upload speed, latency (pink), the ID of the serving base station, and type of cellular connection. This approach can be used to detect the strengths and weaknesses of back-end networks.
  • Kasyk, Lech; Pleskacz, Krzysztof; Kapuściński, Tomasz (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    The definition of dynamic areas of searching for shipwrecks, and/or the movement of pollution across waters of Szczecin Lagoon first requires the knowledge and specification of hydro-meteorological conditions across the area. This article compares wind parameters from various sources of meteorological stations located close to Szczecin Lagoon. The wind speed and direction were obtained from Ueckermuende, I Brama Torowa (Urząd Morski Szczecin), and Kopice (wind meter of Szczecin Maritime Academy). Wind direction data analysis was based on directional statistics methods and tools.
  • Dembińska, Izabela (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    As the year 2022 has come, people expect much and are looking to achieve new goals and face challenges. We are happy to offer to you another issue of the Scientific Journals of the Maritime University of Szczecin. In this issue, we present views, opinions and research findings from different areas of research. Articles have been grouped into the following thematic sections: Civil Engineering and Transport, Material and Mechanical Engineering, Economics, Management and Quality Science and Information and Communication Technology. In Civil Engineering and Transport, there are two articles. The authors of the first study believe that the shoreline is an important geographical zone, and a better understanding of it could have key importance for shore management and creating maps. An analysis of methods for delineating the shoreline was made, where the focus of attention was accuracy. The second paper describes the mathematical formulas for the boundary element method (BEM) governing the dynamics of mooring with buoy equipment. The paper dealt with the semi-submersible FOWT OC4-DeepCwind platform. It was found that by properly selecting the volume and the position of a buoy on the rope the rope’s stress can be reduced by up to 45%. Material and Mechanical Engineering consists of two articles. In the first study, a functional diagram for an automatic sliding mode control system for a three-phase bridge buck current converter was developed. To achieve this, a simulation program was created in MATLAB/Simulink which analysed the dynamic performance of the developed automatic control system, operating in the active rectifier and network current inverter modes. The second article analyses the impact of gas turbine contamination on a drop in airflow, pressure ratio and compressor efficiency. The analysis was based on the assumption that the turbine contamination results in a decreased rated power of the gas turbine and an increased fuel consumption. The case of a shipborne MT30 gas turbine with a nominal power of 36 MW is used in the study. In Economics, Management and Quality Science, we present three articles. Authors of the first study have set out to determine the main conditions for cost-effective production of motor boats in Poland taking into account the implementation of an R&D project. A descriptive analysis was carried out to describe the market conditions for the operation of manufacturers of motor boats, including electric boats. The results obtained allowed defining changes in the business model based on the R&D project. The subject of consideration in the second paper of this section is the concept of a green port. The authors have analysed various initiatives and strategies for ports that are already called “green”. Recommendations based on the analysis are profiled specifically for the Port of Gdynia. The authors of the third study focused on the relationship marketing aspects of container transport. They believe that the strategic competitive advantage in this area of transport is no longer entirely dependent on the basic characteristics of the service provided, and that customer relationships are becoming more important. Authors conclude that container shipping lines must develop effective customer-oriented relationship marketing strategies. Guided by this view, the authors examined selected relationship marketing strategies that are practised in the container shipping industry. Information and Communication Technology presents a study, in which the authors explore the use of ontology for semi-automatic marine vessel navigation and ship-to-ship communication to mitigate collision risk. Examples of how such communication can be used are discussed, based on a comprehensive analysis of selected marine collisions, with particular attention to the communication conducted on ships. The effectiveness of such communication was assessed and compared. I am hoping that the studies presented will meet with wide interest implying discussions and research not only in the discussed research areas, but also going beyond them, giving a stimulus to interdisciplinary and heuristic analyses.
  • Idzior, Marek (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    In recent years, there has been an intensification of work on the autonomy of means of transport, which also applies to ships. Modern ships are already equipped with crew decision support systems and numerous diagnostic systems. Increasingly more systems are installed on ships that can operate without human integration. This situation leads to the development and use of fully autonomous ships. This overview publication briefly describes the main features of the construction and operation of autonomous ships, including some examples of structures already demonstrated in recent years. In summary, the author presents comments that provide a contribution to the discussion on the autonomy of means of maritime transport.
  • Nazemian, Amin; Ghadimi, Parviz; Ghadimi, Aliakbar (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    Hydrofoils are utilized as instruments to improve the hydrodynamic performance of marine equipment. In this paper, the motion of a 2D NACA0012 hydrofoil advancing in water near the free surface was simulated, and a mesh morphing-adjoint based optimizer was used to maximize its lift-to-drag ratio. Ansys-Fluent was used as a CFD solver, and a mesh-morphing tool was used as a geometry reconstruction tool. Furthermore, the Adjoint solver was applied to evaluate the sensitivities of the objective function to all solution variables. Defined control points around the geometry are design variables that move in an appropriate direction through shape sensitivity. The computational results were validated against available experimental data and published numerical findings. Subsequently, different hydrodynamic characteristics of the optimized hydrofoil were compared to those of the original model at different angles of attack of 3, 3.5, 4, 4.5, 5, 5.5, 6, and 6.5°, and optimized shapes were determined. It was observed that the shape of the optimized hydrofoil was totally dependent on the angle of attack, which produced different lift-to-drag ratios. It is also seen that among higher angles of attack at which improvement in the L/D ratio became steady, the drag coefficient was the lowest at 5°. Therefore, it can be concluded that the appropriate angle of attack for a hydrofoil installation on the ship hull is 5°. Further investigation was conducted concerning the evolution of shape optimization, sensitivity analysis, free surface elevation, flow characteristics, and hydrodynamic performance of the hydrofoil at a 5° angle of attack.
  • Pawelski, Jan (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    The grounding of a 400-meter long container vessel, called Ever Given, in the Suez Canal blocked the busiest shipping lane, which is responsible for 12% of seaborne trade, for 6 days. Some shipping companies had to divert their vessels and they had to take a much longer route around Africa to reach European ports. The concerned shipping industry started to look for alternative sea route to the Suez Canal with lesser risk of blockage, without a need to go around Africa. Such routes, which connect the Pacific and Atlantic Oceans, exist in the Arctic and the warming of the global climate makes them more accessible over time but the assessment of their viability requires a multifaceted analysis based on available professional navigational publications, scientific papers, and knowledge of polar shipping realities. Several nautical aspects are taken into account with the purpose of choosing a polar route that is most suitable as an alternative to the Suez Canal. Three routes are under consideration. One of them is the Northern Sea Route in the eastern part of the Arctic Ocean, along the coast of the Russian Federation. The second route is the Northwest Passage through the western part of the Arctic, passing waters belonging to Greenland, Canada, and the United States. The third one passes near the North Pole, a prospective route that may become available for commercial shipping in the future due to Arctic ice shrinkage, and it is known as the Transpolar Route. Analysis of these routes unambiguously point to the Northern Sea Route as the only viable option. Most prospective alternatives to the Suez Canal are technically feasible with the new generation of cargo vessels and they are experiencing a growth in maritime traffic together with a steady development of associated infrastructure. The existing simplified analyses of the transit costs, assuming strait passage in polar waters without any course deviation and the additional fuel that is burnt to overcome increased friction during passage in ice, shows that under present conditions that the Suez Canal Route is still cheaper than any polar transit and, moreover, offers year-round availability. It cannot be ruled out that the upcoming warming of the Arctic climate, and a lowering of the transit tariffs by the Russian Federation may tip the balance in favor of the Northern Sea Route. Presented here is an analysis of the competitiveness of the Arctic Routes in comparison to the Suez Canal from the perspective of the mariner.
  • Gucma, Stanisław; Gralak, Rafał (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    This article indicates the development trends in the construction of offshore wind turbines worldwide, and the characteristics of existing and planned ships for wind turbine installation and maintenance; it presents an approach to design ports with their future operations in mind. Problem: The safety of navigation in port waterways is the basic restrictions for the construction of harbors (terminals) to handle ships used for the construction of OWT and for increasing their size. Navigational risk is a criterion of navigational safety assessment that allows its accurate estimation in port waterways. Method: The article presents the method for dimensioning port waterways for ships serving offshore sea wind turbine transport and construction. Furthermore, a method for determining the navigational risk of jack-up vessels navigating in port waterway areas is presented. Results: The authors have determined conditions for safe operation of these ships in restricted areas and defined the basic condition of navigational safety. The presented method of navigational risk analysis refers to the departure of a loaded ship carrying offshore wind turbine components in the presently designed port terminal in Świnoujście for handling offshore wind farm projects. Conclusion: These are universal methods that can be applied to the design of ports serving vessels that install offshore wind turbines in various types of waters.
  • Bayraktar, Murat; Nuran, Mustafa (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    New systems are produced and developed to meet specific needs, and their reliability is the most important issue. In the maritime industry, evaluating failures in a ship’s propulsion system results in high costs and the loss of prestige for the company. Land/sea fleet employees need to detect and minimize the failures that may occur in ship propulsion systems in advance to ensure the continuity of the ships’ operations. In this study, the recorded failure data of four different ships belonging to a fleet in the last 10 years are used. Failures were examined as a whole since the ships have similar propulsion systems. The obtained failure data were grouped, and the average time to fix the failures was determined by the chief engineer and made suitable for reliability, availability, and maintainability (RAM) analysis. A suitable model was created for grouped failures by Isograph’s RWB software. As a result of the analysis of the propulsion system and its subsystems, the main engine of the ship was shown to have the best reliability. Furthermore, the most important components were the cylinders of the main engine as subsystems. This study highlights the components that are important to the reliability of a propulsion system. Thanks to the RAM analysis, improvements can be pinpointed on a ship’s propulsion system, which will increase the operations of the maritime industry. Reducing failures will further increase the confidence in maritime transport and strengthen its place among the modes of transportation. This study provides a valuable resource for academicians, experts, as well as companies working on reliability, availability, and maintainability in the future.
  • Zhao, Jingzhou (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    This study examines the volatility of the forward freight agreement (FFA) time series in the dry bulk shipping market. Series pattern analysis is first performed to determine the volatility and the characteristics of the unique FFA price time series. It then applies the ARIMA-GJRGARCH model to the Capesize FFA time charter (C5TC) and specific voyage charter one-month contracts (C3, C5 and C7), creating long or short signals, which helps market participants with FFA trading or hedging. In this study, these signals are collected and used to calculate the profit and loss for a specific period. Finally, the model-based return results are compared with the common buy-and-hold strategy. The empirical result suggests that this methodology is effective in generating trading signals, especially in the volatile periods, providing traders with prompt warnings about imminent market shocks. The purpose of the study is to examine whether this volatility-focused method is efficient in modelling FFA time series, and it also provides a handy method that may help market players make more accurate predictions when volatile days arrive.
  • Tepe, Resul; Arabelen, Gamze (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    Recently, technological advancements, globalization, ongoing mergers and acquisitions, and intense competition have dominated the container shipping industry. This situation has led to the formation of major container shipping lines with similar technologies, offering the same service. In such an environment, a strategic competitive advantage is no longer entirely dependent on the basic features of the service provided and customer relationships, which is more difficult to replicate, has gained importance. Container shipping lines must develop customer-centric relationship marketing strategies that cover the whole organization and marketing activities to survive, and maintain their profitability, in the current competitive environment of the industry. However, these strategies and their implementation are not precisely defined in the container shipping industry. Therefore, this study explores the relationship marketing strategies that are practiced in the container shipping industry. Data is collected via 22 semi-structured interviews with container shipping partners (i.e. container shipping lines and freight forwarders). Loyalty programs and relationship pricing are the most often mentioned relationship marketing strategies that foster customer loyalty in these interviews.
  • Motallebi, Mohammad; Ghassemi, Hassan; Shokouhian, Mehdi (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    In this paper, to improve the mechanical behavior of DeepCwind semi-submersible floating offshore wind turbine (FOWT) platform mooring lines, the nonlinear catenary cables of the platform were divided into multi-segment and intermediate buoys. Mathematical formulations of the boundary element method (BEM) governing the dynamics of mooring line systems with buoy devices were described. This study was applied to the OC4-DeepCwind semi-submersible FOWT platform, which is designed for a 200-meter water depth with mooring lines consisting of three catenary steel chain cables at 120° angles to each other. The dynamic response of the multi-segment catenary mooring lines with different buoy radiuses and different positions along the cables was investigated. The full-scale platform was modeled in ANSYS-AQWA software, and the simulations were performed under harsh offshore conditions. The mooring line’s general arrangement, tension, strain and uplift force for different buoy radiuses and their position along the cable are presented and discussed. Moreover, platform motions in three directions (surge, heave, and pitch) were also analyzed. It was concluded that by correctly selecting the buoy volume and position along the cable, the tension of the cable may be reduced by up to 45%. By incorrectly selecting the buoy, the results caused adverse effects.
  • Jarmusz, Jan; Marzantowicz, Łukasz (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    The purpose of this article is to determine the main conditions for the profitable production of motorboats in Poland by taking into account the implementation of an R&D project. Theoretical considerations were made for the analysis of the main considerations based on the VT Sport case study. A descriptive analysis was carried out, indicating the market conditions for the functioning of enterprises producing motorboats, including electric boats. The effects of the implementation of the R&D project for the production of electric motorboats were indicated. Results were obtained for defining changes in the business model through the use of the R&D project, and a critical discourse on the effectiveness of electric propulsion of motorboats was carried out.
  • Herdzik, Jerzy (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    Deterioration in the performance of gas turbines is a well-known phenomenon occurring during their operation. The most important form is a decrease in the internal efficiency of the compressor and turbine due to fouling, which is the most significant deterioration problem for an operator. This article presents the effect of gas turbine fouling as a drop in airflow, pressure ratio, and compressor efficiency resulting in a reduction in power output and thermal efficiency. This resulted in a decrease in the nominal power of a gas turbine and an increase in the fuel consumption (heat rate). The fouling effects were described using the example of the MT30 marine gas turbine with a nominal power of 36 MW. The estimated profit loss during the operation of the gas turbine was within the range of 1–10% of the total fuel consumption cost. A 2% deterioration in the output of a gas turbine accounted for US$ 10,000–20,000 per year and 1 MW of gas turbine nominal power (according to marine fuel prices in 2019–2020) – this means at least US$ 300,000 annually for an MT30. Due to the low accuracy of fuel consumption measurements, another possibility was provided. The correlation between the gas turbine power deterioration and thermal efficiency was presented, which made it possible to estimate the increase in the specific and total fuel consumption when the nominal power deterioration is known. Two linear approximations were proposed to calculate increases in the annual operating costs for an MT30 due to fouling.
  • Hatłas-Sowińska, Paulina; Wielgosz, Mirosław (Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie, )
    This article explores the use of ontology for semi-automatic marine vessel navigation and ship-to-ship communication to mitigate collision risk. Semi-automatic vessel communication is a step towards automatic communication for autonomous ships. Examples of how such communication can be used is discussed, based on a comprehensive analysis of selected marine collisions, with particular attention to the communication conducted on ships. The effectiveness of such communication was assessed and compared. The suggested solutions are based on the review of official reports from accident investigations. The novelties of this work include original ontologies and interfaces. Through this work, it could be possible to fully automate communication processes between ships. In future work, the research results in this work will be used to create a system of automatic communications for manned and autonomous vessels.

Search repository

Advanced Search


My Account

RSS Feeds