Dear Readers, We are pleased to present you the next issue of our journal, Scientific Journals of the Maritime University of Szczecin. Fourteen articles are presented in this issue, the problems of which fall under the following subject areas: Civil Engineering and Transport, Material and Mechanical Engineering, Environmental Engineering, Mining and Power Engineering, Information and Communication Technology, Economics, Management and Quality Science, Sustainability Management. We are pleased that the manuscripts submitted to us cover a wide field of research, thus giving our readers the opportunity to analyze and give their opinion on a variety of research problems. In the Civil Engineering and Transport section, we present two studies. The first study investigated the effects of buoys and solid mass on mooring lines and the dynamic response of the floating platform. The results of the analysis show that increasing the number of buoys at constant volume contributes to a decrease in the amplitude of wave and tilt motion, while lifting motion increases slightly. On the other hand, adding a buoy and clump weight to the mooring line reduces the tension of the vibration amplitude. The second study characterizes the distribution chain of liquefied natural gas in Poland, paying particular attention to the possibilities of road transport. It has been noted that during transportation and storage, LNG vaporization, known as boil-off gas, is a significant problem leading to an increase in tank pressure. Hence, one solution to this problem is to compress it to high pressure, which produces compressed gaseous fuels. In the Material and Mechanical Engineering Section, we have six manuscripts. As the authors write in the first study, one of the primary hazards associated with the operation of marine and deep-sea vessels-particularly ship power plants-are fires and explosions, which cause accidents and incidents with an average frequency of up to every 60 days. The article discusses the explosion hazard status of the crankcase of main propulsion engines of various types of vessels. The evaluation was based on the results of statistical analysis of historical data from 1972–2018. Based on the analysis, it was generally shown that the risk of a crankcase explosion affects ships of all ages and that the number of serious incidents remains constant over the period studied. It is interesting to note that half of all incidents occurred on vessels younger than 15 years. The second article describes the prospects for ultrasonic cleaning of shell-and-tube heat exchangers used, among others, on ships. This is because the main problem of seawater heat exchangers is their clogging – as a result of the operation, over time a process of overgrowth begins (e.g., algae), leading to reduced efficiency. In order to obtain information about the distribution of ultrasonic power inside the reactor, the authors conducted a finite element simulation using a designed test reactor represented by a shell-and-tube heat exchanger with ultrasonic-assisted cleaning. The simulation results are presented in the article. The authors 6 Scientific Journals of the Maritime University of Szczecin 71 (143) of the next article in this section point out that concrete is currently the most widely used man-made composite material and is second only to water across the range of materials used. This paper presents the results of a study of the effect of partial replacement of Portland cement with fly ash on the strength parameters, frost resistance and carbonation of concrete in comparison with a reference concrete and concrete containing a conventional additive – silica fly ash. The results obtained confirmed the feasibility of producing plain concrete modified with fly ash from thermal treatment of sewage sludge, while demonstrating the compliance of concrete parameters with environmental requirements for the leaching of heavy metals. Concrete was also analyzed in the following article. It presents the effects of the addition of steel and propylene fibres on the mechanical properties of floor concretes, such as compressive and tensile strengths in the flexural test. It was shown that the amount of steel fibres dosed in the study, regardless of their shape, does not adversely affect the consistency and workability of the concrete mixture. On the other hand, the addition of polypropylene fibres has a significant impact on the properties of the concrete mix. In the introduction of the following article, the authors explain that a digital twin is a digital replica, a mathematical model of a given object, product, process, system or service. It enables the acquisition of a significant amount of data and can be used to obtain comprehensive knowledge about a given object, its behaviour and reactions. The authors analyzed the operation of a rotating bearing in a wind turbine structure using a digital twin model, and more specifically, analyzed the distribution of loads prevailing in the rotor blade bearings at wind turbine limit loads. The basic types of the most commonly used rim bearings for wind turbine applications are analyzed. In doing so, a methodology for building computational models of rim bearings using the finite element method was developed, as well as an original method of simulating rolling elements with rod elements (for rollers and super elements) for load-bearing balls was proposed. The subject of research in the last article of this section is stainless steels widely used in various automotive parts. Knowing that some of them are exposed to the external environment, the pitting corrosion resistance of two austenitic stainless steels was analyzed, i.e., AISI 304 and AISI 316L in road salt solutions of 5% wt. and 10% wt. Experimental results confirmed the lower pitting corrosion resistance of AISI 304 stainless steel in a 10% wt. road salt solution. We present one article in the Environmental Engineering, Mining and Power Engineering section. It notes that the biggest problem of creating a numerical model of a coal seam is the insertion of discontinuity lines: faults, seam connection lines, wedging, etc. Therefore, proprietary methods were developed to determine the spatial location of faults, implemented in Geolisp in CAD. A method is presented for calculating the spatial position of a fault based on existing contours reaching it from both sides, a method based on the assumption that the slope of the deck upstream and downstream of the fault is constant, a method based on making independent surfaces of the updip and downdip sides with kriging extrapolation, a method based on transferring the fault from the deck above it or the Carboniferous roof. It was assumed that the correct introduction of the fault course is important for the accuracy of forecasting the impact of mining operations on the rock mass and surface. Two studies make up the Information and Communication Technology section. The Automatic Identification System (AIS) device is mandatory on ships that comply with the International Convention for the Safety of Life at Sea (SOLAS), the first study reads. AIS is designed to monitor vessel traffic in order to improve shipping safety. In their study, the authors compare the execution speed of geospatial queries in the relational database engine PostgreSQL and the non-relational database engine MongoDB. Four AIS datasets, four test polygons with different numbers of vertices, and a reference point on the fairway were defined for the study. The tests were used to evaluate the execution of queries in the database, which shows the number of ships in a given area and the number of ships within a given distance from a defined point. Test results say that test queries are executed faster, and data stored in the database takes up less disk space in MongoDB compared to PostgreSQL. Justifying the need for the research, the authors say that faster geospatial analysis of AIS messages can improve navigation safety by detecting dangerous situations earlier. The second article in this section highlights the use of satellite tracking during an environmental disaster at sea and evaluates the feasibility of using remote sensing images captured by satellites using multispectral cameras and Synthetic Aperture Radar (SAR). The purpose of the analysis is to evaluate selected remote sensing methods for detecting and tracking marine debris. The research value of the analysis is determined by the fact that the study was conducted in real-time at the time of the incident. The Economics, Management and Quality Science section is filled with one article. The object of research inquiry in this case was the pallet. The purpose of the article was to present the issues of pallet pool players’ Zeszyty Naukowe Akademii Morskiej w Szczecinie 71 (143) 7 strategies and the organizational, operational and market challenges they face in such a way that they are better understood by all supply chain players. The author proposes adopting a value-added synergy perspective as an alternative, understood as different and complementary, rather than excluding opportunities for other approaches to supply chain value. The final section, Sustainability Management, begins with a study highlighting the impact of increasing container throughput in the northern Adriatic ports on air quality. A comparative analysis of air quality consisting of certain environmental parameters taken from selected measuring stations near the container terminals of the northern Adriatic ports of Rijeka, Trieste, Koper and Venice was carried out. The study showed that the increase in container throughput in the ports of the northern Adriatic did not affect the deterioration of air quality in the urban areas of the various port cities. Air quality values in the ports of the northern Adriatic are well below the limits set by the EU Directive in the area of air quality (2008/50), i.e., they do not negatively affect the health of the residents of the analyzed cities. The subject of the next article was the relationship between the seaport and the city in the aspect of sustainable development, particularly in environmental terms. The consideration was based on the thesis that the introduction of the concept of sustainable development in the port can stimulate the creation of green cities. A case study of the sustainable development of the Twin Port of Bremen was used in the deliberations. Port development has been shown to stimulate GDP growth, increase employment, develop urban infrastructure and contribute to the enrichment of port cities. And the development of ports on an environmental basis also becomes a stimulus for green city development. I hope that the presented studies will meet with wide interest, and at the same time inspire various interdisciplinary thoughts, discussions and research. dr hab. Izabela Dembińska, Associate Professor Editor-In-Chief Szczecin, 30.09.2022

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.

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.

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%.

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.

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 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.

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.

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.

The largest problem that we encounter when creating a numerical model of a hard coal deposit is to insert discontinuity lines representing faults, seams junction lines, wedging, etc. The faults introduced on the map of the seam are mostly flat polylines, while we do not know the altitude ordinate. In order to determine the spatial position of the faults, authoring methods have been developed and implemented in the Geolisp software and in the CAD system. This article presents the method based on calculating the spatial position of the fault with respect to the existing contours, which arrive at it from both sides, the method based on the assumption that the inclination of the seam in front of and behind the fault is constant, the procedure involving the performing of independent surfaces of the upthrow and downthrow side with extrapolation by the Kriging method, and the procedure requiring the transfer of the fault from the above-lying seam or a Carboniferous roof. The solutions given in the article are successfully used in most mines in Poland. The correct introduction of the fault course is important for the accuracy of forecasting the impact of the mining operations on the rock mass and the surface area.

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.

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.

A flat wooden pallet, being a simple logistics carrier in terms of its structure, can nonetheless be treated as a highly specialized logistical and marketing object applied in complex supply chains. Rigorous measures taken to standardize pallets are predominantly aimed at ensuring the highest possible safety level for the transported products and people handling the freight units during the complex logistical processes that involve pallets along supply chains. The goal of this article was to increase understanding of the operating strategies employed by entities using pallet pools, as well as the organizational, operational, and market challenges faced by them. It was hoped to achieve this goal via both theoretical and empirical studies. To this end, the research study applied theoretical synthesis and empirical evidence derived from primary research based on the industrial, transport, forwarding, and logistics markets. At the same time, the theoretical context was based on the literature on the subject, related to wooden pallet issues and their special role in logistical processes. Challenges connected with decisions made to enable effective and efficient management of pallet pools were addressed at legal and regulatory, as well as organizational and operational, levels. Diverse courses of action identified in several stakeholder groups were reflected in the adopted philosophy of managing the main feeding streams of pallet pools. Though limited to just the Polish market, the research study was sufficiently representative due to the strategic share of the European and global market of standard flat wooden pallets. The author proposes taking a perspective of value-added synergy as an alternative (to be understood as different and complementary rather than excluding possibilities) to other ways of approaching the value of supply chains. The undertaken considerations may contribute to increasing the awareness of the importance of taking a pallet, so common from the technical and technological point of view, as a value-added carrier in scientific considerations, due to its paradoxically low individual economic vulnerability.

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.

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.