This article aims to compile, describe and compare three different models taken from the literature describing the causes of explosions in the crankcases of marine engines. Each of the models has a different level of detail and was prepared with a different purpose. However, the same process, explosions in crankcases, was analyzed in all cases. A statistical evaluation of the frequency of events leading to explosions, a model built using failure mode and effects analysis (FMEA) and a model based on fault tree analysis (FTA) are described in turn. The FTA model drawn from the literature formed the basis for further analysis. Values of important measures of all elementary events of the fault tree were calculated using the Birnbaum reliability measure, Vesely-Fussell measure, Birnbaum structural measure, criticality measure and improvement potential. The percentage importance values of all events determined using these importance measures were compared. The results obtained from the application of each model were evaluated. The results of the models were compared with each other, and an approach using all three models supplemented with diversion analysis was proposed.

Stainless steels are widely used for various automotive components. Some of them (e.g., parts of the exhaust system) are exposed to the external environment. In winter conditions, they are affected by chloride containing road salt solutions, which can lead to the local corrosion of these stainless steel parts. The presented paper is focused on the pitting corrosion resistance of two austenitic stainless steels (AISI 304 and AISI 316L) in 5 wt% and 10 wt% road salt solutions. The evaluation and comparison are based on the potentiodynamic polarization test method carried out at the temperature of 20 ± 2°C. The pitting potentials were determined from the polarization curves. Local corrosion damage of exposed surfaces caused by potentiodynamic polarization in the used solutions was observed by optical microscope. Experimental results confirmed a worse pitting corrosion resistance case, especially for AISI 304 stainless steel in 10 wt% road salt solution.

A digital twin is a digital replica, a mathematical model of a given object, product, process, system, or service. A digital twin enables the attainment of a significant amount of data and it can be used to gain comprehensive knowledge about a given object, its behaviors, and reactions. The constant ability to monitor the product and its reactions contribute to its improvement and the exclusion of errors, as well as its optimization, which in turn allows for a more perfect product. This article presents a model of a digital twin for the analysis of the operation of a slewing bearing in the structure of a wind turbine. The quality of the bearing is directly related to the quality of the materials from which they were made, the process of thermo-chemical treatment, and the accuracy of all its elements, as well as its proper assembly. The bearings are characterized by very narrow tolerances. Errors in the shape of cylindricity cause distortion of the bearing raceway, stress accumulation, and jamming of rolling parts. This leads to rapid bearing wear as a result. The condition for the approval of bearings for sale is the successful passing of all tests, both geometric and strength. This is to develop quality standards that bearing suppliers must meet. The article presents an analysis of the load distribution that prevail in rotor blade bearings at the limit loads of a wind turbine. The basic types of the most commonly used coronary bearings for wind turbine applications were considered. A methodology for constructing computational models of slewing bearings, using the finite element method, was developed. An original way of simulating rolling parts with rod elements – for rollers and superelements – for the support balls was proposed. A numerical FEM model of a slewing bearing with a wind turbine rotor hub is presented. The calculations accounted for the susceptibility of the bearing rings and hub, as well as the stiffness of the mounting screws. Areas of bearing raceways, where rolling parts achieve the greatest loads, have been identified. Demonstrated by diagrams are the deformations of the rotor hub seats and bearing rings.

This paper presents the effect of the addition of steel and propylene fibers on the mechanical properties of floor concretes (compressive and tensile strengths in the bending test). The polypropylene fibers used in the tests (fibrillated and single fibers) are dosed in the amount of 0.5 kg/m3 to 2 kg/m3 , and the straight and hooked steel is dosed from 10 kg/m3 to 25 kg/m3 . It is shown that, after 28 days of maturation, the highest compressive strength is achieved by concretes containing the addition of 25 kg/m3 of hook-like steel fiber. In addition, the influence of the fiber content on the consistency of the concrete mix and workability is investigated. It was shown that the amount of steel fibers dosed in the tests, regardless of their shape, did not adversely affect the consistency and workability of the concrete mix. On the other hand, the addition of polypropylene fibers has a significant impact on the characteristics of the concrete mix. The addition of 2 kg/m3 of polypropylene fibers caused the change of consistency from S4 to S1/S2 and worsened the workability of the mixture. All of the tested series of the concrete are created using the same technology. The concrete production technology reflects the concrete production technology for flooring concretes.

Seaports and cities are internally linked, and the port can have a strong influence on the city, especially in the environmental aspect. Port authorities around the world are striving for greener forms of port management to adapt to state policy and to increase their economic and environmental competitiveness. The introduction of the concept of sustainable development in the port can stimulate the creation of green cities. This paper uses a case study to analyze the sustainable development in the Twin Port of Bremen. The aim is to distinguish the green port’s impacts that can stimulate the development of the green city concept. It is shown that the port development stimulates GDP growth, increases employment, urban infrastructure development, and the overall enrichment of port cities. Using the presented analysis of the green port, the most important affecting factors are proposed.

This study characterizes the distribution chain of liquefied natural gas (LNG) in Poland, using the terminal in Świnoujście as the “source of LNG”. The focus is primarily on the possibility of LNG distribution for road transport, taking into account the effective use of its energy potential. During the transport and storage of LNG it was found that the evaporation of LNG, the so-called boil-off gas (BOG), is a significant problem that leads to an increased pressure in the tank. Therefore, the possibility of using BOG in individual links of the LNG supply chain is indicated. One prospect is its compression to high pressure, which produces compressed natural gas (CNG) fuels. Thus, this paper specifies the influence of the initial BOG gas pressure on the unit compression work and analyses the change in the compression unit work, which depends on the final CNG fuel pressure, with a specific assumption for the BOG pressure.

Dear Readers, We are living faster and more intense these days. This dictatorship of time is also visible in the world of science. The lifetime of research results shortens progressively. Research problems are quickly becoming out of date. It is not a destructive factor for researchers but a challenge they need to face. The only thing to comprehend here is that research needs to be carried out quickly and flexibly. Obviously, it is not an easy task as new trends and, consequently, new research problems appear more often as well. We are glad to present to you a new issue of our journal, the Scientific Journals of the Maritime University of Szczecin. This issue presents views, opinions and research results grounded in various research fields. We grouped the submitted papers into the following themed sections: Civil Engineering and Transport, Material and Mechanical Engineering, Information and Communication Technology, Sustainability Management. The Civil Engineering and Transport section holds five articles. In the first one, the authors present trends in building offshore wind turbines and characterise ships used for installation and maintenance of wind turbines. The analysis is based on the assumption that safety of sailing on port waterways is the basic limitation in building ports and terminals for handling ships used to build OWT and expanding their size. The goal is to present a method of measuring port waterways for ships used for transporting and building offshore wind turbines. The author of the second article claims that recent years brought about more intense works on autonomous means of transportation, including sea ships. This review presents key features of the construction and exploitation of autonomous ships. The analysis presented in the third article of this section views hydrofoils as instruments to improve the hydrodynamic aspects of maritime equipment. The authors simulated the movements of a 2D NACA0012 hydrofoil moving in the water close to its free surface, with the optimiser based on the coupling with the net’s morphing used to maximise the lift-to-pull ratio. It was observed that the shape of the optimised hydrofoil depends on the angle of attack, which triggered various lift-to-resistance coefficients. This served as a basis for a general conclusion that the optimal angle of attack for installing a hydrofoil on the ship’s hull is 5°. The next paper was inspired by the 400 m container ship called Ever Given was grounded on the Suez Canal, blocking the busiest shipping lane – handling 12% of global sea trade – for 6 days. That event enforced finding an alternative waterway for the Suez Canal, with a smaller risk of being blocked and without the necessity of going around the entire African continent. Such routes joining the Pacific and the Atlantic are found in the Arctic and the global warming make them increasingly accessible. However, assessing their longevity requires a multifaceted analysis based on available professional navigation publications, academic works and knowledge regarding polar sailing conditions. The paper discusses three alternative lanes: the Northern Sea Route in the eastern part of the Arctic Ocean along the coast of the 6 Scientific Journals of the Maritime University of Szczecin 70 (142) Russian Federation, the Northwest Passage through the western part of the Arctic, avoiding waters belonging Greenland, Canada and the USA, and a route near the North Pole, known as the Transpolar Sea Route. The analysis of those lanes clearly points to the Northern Sea Route as the only option currently viable. The last paper in this section discusses the changeability of time series in Forward Freight Agreements on the market of dry bulk cargo. Firstly, it determines the changeability and characteristics of unique time series for prices in FFA. Next, it applies the ARIMA-GJRGARCH model for time-based charter within Capesize FFA and particular one-month charter contracts for cruises, which creates long or short signals that help market users in FFA-based trade or hedging. The aim of the research is to determine whether this method focused on changeability is efficient in modelling FFA time series and whether it helps the market players in more precise estimates regarding unstable days. The Material and Mechanical Engineering section features one article. It proves that the assessment of propulsion system failure in a ship triggers excessive costs and a decrease in the company’s prestige in the maritime business. The employees of land/ship crew have to detect and minimise failures in ship propulsion systems in advance to ensure the continuity of ship operation. The paper uses registered data on the failures in four different ships. The failures were examined thoroughly as the ships have similar propulsion systems. The investigation into the propulsion system and its subsystems shows that the ship’s main engine is the most reliable. Furthermore, the most crucial elements were the main engine’s cylinders as subsystems. The research is a valuable source of information not only for scientists, but also for experts and companies working on the reliability, accessibility and maintenance of ships. The Information and Communication Technology section features one paper. It notices that as a result of the accessibility of mobile devices and common broadband access worldwide, the number of Internet users is constantly growing and their awareness when it comes to the absorbed content is increasing with it. Many service providers and operators focus on monitoring Quality of Network and Quality of Service parameters, especially those affected by throughput and delays. However, for most end users, quality is viewed as subjective Quality of Experience which is a mixture of several individual factors. The article presents QoN assessment carried out under working conditions in real time on the university campus, with particular focus on general efficiency of the mobile networks. The Sustainability Management section presents a paper stating that the determination of dynamic areas of searching for wreckage and/or movement of pollutions through the waters of the Szczecin Lagoon requires most of all the knowledge and identification of hydrometeorological conditions in that area. For this reason, the authors compared wind parameters from various sources at the meteorological stations located near the Szczecin Lagoon. Wind speed and direction were obtained from Ueckermuende, I Brama Torowa (Szczecin Maritime Office) and Kopice (anemometer of the Maritime University in Szczecinie). Analysing data on wind direction was based on methods and tools of directional statistics. I hope that the papers included in this issue will trigger broad interest and stimulate further reflections, discussions and research.

Concrete is currently the most widely used man-made composite material and second only to water in the entire range of materials used. It is a material with a high potential to adapt to specific operating conditions and can be made from local raw materials (aggregate, cement, water, and mineral additives), which can be selected to minimize the carbon footprint. The use of fly ash from the thermal conversion of sewage sludge in concrete is in accord with the advice on waste management proposed in the European Union. This paper presents the results of research on the effect of the partial replacement of Portland cement with this material on the strength parameters, frost resistance, and carbonation of concrete compared to reference concrete and to concrete containing a conventional additive – siliceous fly ash. In addition, the potential environmental impact of the use of sewage sludge ash was investigated by determining the leachability of heavy metals. Concrete mixtures of C20/25 ordinary concrete, based on CEM I 42.5R Portland cement, with varying ash contents comprising 0–20% of the cement mass, were produced for the experimental work. The obtained test results confirmed the possibility of producing plain concrete modified with fly ash from the thermal treatment of sewage sludge and the concrete’s compliance with the environmental requirements relating to the leaching of heavy metals.

This paper seeks to highlight the impact of the increasing container throughput in northern Adriatic ports on air quality. A comparative analysis of air quality is given, which consist of certain environmental parameters at selected measuring stations near the container terminals of the northern Adriatic ports Rijeka, Trieste, Koper, and Venice. The parameters were analyzed based on a limited amount of air quality monitoring data for the port areas. As the port transport sector increases pollutant emissions, the results of these analyzes can also be used to take appropriate measures to reduce these particulate matter emissions. The aim of this paper is to determine the impact of increasing the container throughput within the ports of the northern Adriatic Sea on air quality, based on certain environmental parameters related to the shipping or delivery of containers by road. The results of the research, based on available data, have shown that the increase in container throughput of the northern Adriatic ports has not decreased the air quality of urban areas of the respective port cities. The air quality value of the northern Adriatic ports is substantially below the limits set by the EU Air Quality Directive (2008/50), thus it does not affect the health of the inhabitants of the analyzed cities.

The current article describes the basics and prospects of the ultrasound-assisted cleaning of shell and tube heat exchangers that are used, e.g., on ships. A main issue of seawater heat exchangers is their clogging. After a certain operating time, the fouling process (barnacles, algae, etc.) starts, which results in a decreased performance that produces a noticeably reduced flow rate and a declining transmission of heat energy. Based on the current state of the art, heat exchangers are cleaned by mechanical or chemical (CIP, cleaning in place) methods. Especially on ship-based systems, a mechanical cleaning in very narrow spaces can be difficult and the usage of chemicals for CIP may generally be prohibited. An ultrasound-assisted cleaning would significantly save time and manning. Based on previous experiments, a test reactor represented by a shell and tube heat exchanger with ultrasound-assisted cleaning has been designed. A FEM (finite element method) simulation is performed to provide information about the ultrasound power distribution inside the reactor. Further, the assembly and commissioning of the test reactor with associated comparative measurements were carried out, which are also reported here.

This paper discusses the use of satellite tracking during an environmental disaster at sea, and it assesses the possibility of using remote sensing imagery captured by satellites using multispectral cameras and synthetic-aperture radar (SAR). This study is based on scientific literature and satellite tracking of the X-Press Pearl container ship disaster, which involved the EO-Browser platform. The purpose of this paper is to assess selected remote sensing methods for detecting and tracking marine pollution. The first part of the paper discusses satellite tracking of the X-Press Pearl disaster. The second part focuses on evaluation of the quality of remote sensing imagery from satellites and aircraft, when taking weather conditions into consideration. It should be noted that the research was conducted in real time when the incident occurred. News about the accident was also tracked in real time, allowing for a thorough analysis of the incident and, thus, an assessment of the different sensing systems. Although research on such disasters is crucial for the protection of the marine environment, scientific literature on this topic remains limited. This research area is very important for the protection of the marine environment, in the context of looking for solutions to these issues.

The Automatic Identification System (AIS) device is mandatory for ships that comply with the International Convention for the Safety of Life at Sea (SOLAS). AIS is intended for vessel traffic monitoring to improve shipping safety. In the examined area, the base station received 22 128 345 messages in April 2019. Approximately 80% of these messages included position reports, which were subjected to geospatial analysis. One possible utilization of AIS messages is used in an intelligent maritime transport statistics production system called TranStat in the Gospostrateg project. This specific study compares the speed of executing geospatial queries in a relational PostgreSQL database engine and a non-relational MongoDB database engine. For the purpose of this research, we have defined four AIS datasets, four test polygons of varied number of vertices, and a reference point on a fairway. The tests were used to assess the execution of the queries in a database that returns the number of ships located in a predefined area and the number of ships located at a preset distance from the defined point. It has been determined from the test results that test queries are performed faster and data stored in the database occupy less disk space in MongoDB than in PostgreSQL. Faster geospatial analysis of AIS messages may improve the navigation safety by earlier detection of dangerous situations.

The purpose of this paper is to present the results of a query aimed at assessing the validity of the topic of crankcase explosions prevention in the main marine engines. The study takes into account the engine type, engine manufacturer, ship’s age, accident severity, ship’s location at the time of the incident, and the share of fatal accidents in the analyzed population of crankcase explosions. One of the primary hazards associated with offshore and deep-sea ship operations – and primarily ship power plants – are fires and explosions that result in accidents and incidents with an average frequency of 60 days. This paper discusses the actuality of crankcase explosion hazards in the main propulsion engines of various types of sea vessels. The assessment was made based on the results of a statistical analysis of historical data from 1972 to 2018. The methodology consisted of three stages: (1) a selection query to obtain the source data, (2) analysis of the obtained results (data separation, extraction of additional information, and statistical analysis), (3) synthesis of the obtained information, and drawing conclusions about the numerical indicators describing the statistical distribution of individual events for the given evaluation criteria. The analysis showed that the risk of crankcase explosions affects ships of all ages – both in crosshead (31%) and trunk piston engines (61%) – and that the number of serious incidents (67%) remained constant over the investigated period. Half of all incidents occurred on vessels younger than 15 years old. 58% of explosions took place in engines of the most popular prime movers manufacturers. The probability that a main engine crankcase explosion will result in injury or death is 17.34%.

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.

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.