Dear Readers, I am pleased to present the fourth 2020 issue (No. 64) of the Scientific Journals of the Maritime University of Szczecin. This issue contains the research results and views of the authors of seven articles that are compiled into three subject groups: Civil Engineering and Transport; Mechanical Engineering; and Economics, Management and Quality Science. The Civil Engineering and Transport section begins with an article that examines the relationship between the occurrence of failures in selected types of buses and the time of their occurrence using the public transport of Lublin as an example. The second article presents the current state of research on the technical, legal and administrative problems that need to be solved in order for unmanned ships to be used widely by society. There are four papers in the Mechanical Engineering section. The first paper presents a numerical study of the hydrodynamic parameters of a modified hourglass-type FPSO (Floating Production, Storage and Offloading) ship with different geometric parameters. The second paper evaluates the atmospheric composition after degassing and ventilating a ship’s cargo tank after a washing process with reference to the entrance and its visual inspection The author of the third article presented methods of joining (welding and sealing) single-polymer composite materials in a hot air stream. The last study in this section determined the vibration- activity parameters of a hermetic harmonic drive to evaluate a gearbox in terms of its manufacturing quality and wear-related deterioration. The third section, Economics, Management and Quality Science, contains one article. The article synthetically presents the process of financing investments related to the construction and purchase of ships, presenting, among other things, the concept of shipbuilding cycles and the relationship between the shipbuilding industry and the shipping market. The articles presented demonstrate the authors’ continuing practical inspiration and contribute to interesting scientific inquiry. I am aware that the presented articles are only a modest expression of these ideas, but believe that they will provide a basis for reflection, discussion, and broader research. dr

This paper discusses the problem of atmosphere composition assessment related to entrance and inspection of a vessel cargo tank after washing, gas-freeing and ventilation. A correct assessment of the atmosphere before an entrance into the cargo tank or other enclosed spaces is a basic condition for the possibility of safe crew working. An assessment of the flammability hazard, presence of toxic or dangerous gases for human, and the oxygen concentration should be completed. In this regard, the ship-owner should prepare adequate procedures before an entrance, during work, and in emergency situations. The officers responsible should perform an assessment onboard the vessel their decisions are crucial for the safety of successive operations. A proper assessment of oxygen concentration in the air into the cargo tank or an enclosed space after the measurement is one of the primary problems which should be properly interpreted. This concerns such situations when the measured oxygen concentration into the tank reaches the value over 22% and below 20.6% of volume (mole) contribution (v/v). Air temperature in the 5–25°C range may create additional threats. This manuscript clarifies the controversial information included in manuals concerning the safety of entrance into enclosed spaces on vessels and the ship-owners procedures concerning the safety precautions for preparing, entrance, protection, and work inside the cargo tanks.

The aim of this study was to examine the relationship between the occurrence of selected types of failures and the time and season of their occurrence in public transport buses in the city of Lublin. The analysis was carried out for buses operated in the Municipal Transport Company within the past 3 years. The chi-squared analysis showed that during operation, there are significant differences between the failures and the annual season, but there are no differences between the frequency of failures and the time of day.

This paper presents a numerical investigation of the hydrodynamic performance of a modified sandglass-type FPSO (Floating Production, Storage and Offloading) with different geometrical parameters. The influence of the roll damping plate on heave and pitch motions of the FPSO was studied in regular waves. To estimate the hydrodynamic performance and utilize the results on the design stage of the FPSO, the boundary element method (BEM) was used. Furthermore, the hydrodynamic performance of two cylindrical and sandglass-type FPSOs under the same conditions was compared in different waves. Five sandglass-type FPSOs with dissimilar inclination angles were utilized with the constant draft. The effects of different inclination angles, including various radii of water-plane part of the floating object on hydrodynamic responses and wave forces applied to the FPSO, were investigated, and presented here. Numerical results were compared against published experimental data of a sandglass-type model, and good agreement was achieved. Based on the simulation results, a conclusion that a sandglass-type FPSO with the inclination angle of 35 degrees proposes proper hydrodynamic performance in both heave and pitch motions for all ranges of wave frequencies was reached. In addition, as it was predicted, the effect of heading sea on a sandglass-type FPSO was significant compared to other wave directions. Finally, by adding a damper plate to the floor of the platform, its hydrodynamic performance is improved. For numerical analysis of the modified FPSO, three different damper sizes are used to investigate its effect on the reduction of the pitch motion amplitude in waves.

Unmanned, remotely or autonomously ships are the fastest growing new technology in maritime transport in recent years. The design of unmanned vessels envisions clean, emission-free electric propulsion. The costs of building physical models and target vessels are high, but the expected benefits are generating increasing interest in such vessels. This article presents the current state of research in the field of unmanned ships and the technical, legal and administrative problems that need to be solved in order for these ships to be used by the general public.

The aim of the article is a synthetic presentation of the complex process of financing investments related to shipbuilding and purchase. The first part presents the concept of shipbuilding cycles and the relationship between the shipbuilding industry and the shipping market. The paper then reviews the concepts and literature related to the shipbuilding industry, shipbuilding financing, and ship purchase. Lastly, the current state of the shipbuilding market is described. The results of the analysis indicates possibilities of financing the purchase of new vessels including mortgage bonds.

Dear Readers, I am pleased to announce the publication of the third edition (63(135)) of the Scientific Journals of the Maritime University of Szczecin in 2020. This edition contains the findings and opinions of the authors within thirteen articles, which are grouped into six fields: Civil Engineering and Transport, Environmental Engineering, Mining and Energy, Electrical Engineering, Mechanical Engineering, Economics, Management and Quality Science, and Information and Communication Technology. The Civil Engineering and Transport section begins with an article in which the authors provide an FMECA for a thermal deburring machine of a Slovak company to develop an efficient maintenance policy. The second article also covers maintenance issues by addressing freight cars used in railway transport. The authors used railroad car operation, maintenance, and failure data to establish a methodology to calculate the probability of failure and thereby determine the risk levels in the rolling stock maintenance policy. The author of the third article noted that the continued growth of transport systems and the extensive activities related to the system user safety require the development of methods to assess how the extension or upgrading of road infrastructure impacts road safety. The author aimed to develop an assessment concept that will form part of a comprehensive methodology for analyzing the operational reliability of transport systems. Conceptualized in the article is an assessment of the impact of road infrastructure on road safety that refers to the GAMAB and Road Safety Impact Assessment methods reported in the literature. The concept is based on a comparative analysis of the state of road infrastructure before and after expansion or upgrades, based on publicly-available data. The last article in this section deals with digitization, one of the most urgent modern determinants of economic activity. The authors consider the digitization of transport as a tool for achieving the European Union’s policy objectives set out in the Digital Single Market Strategy for Europe. For railway transport, digital innovation is necessary to increase its competitiveness, and one of the tools for the digital transformation of the railway is the fifth-generation of wireless communication systems (5G). The purpose of this article is to show the advantages of 5G deployment for railway operators. It describes unique flexibility in the allocation of 5G network resources, depending on the existing needs of rail traffic. The Environmental Engineering, Mining and Energy section contains study, that elaborates on the modern technologies used for the production and utilization of methanol. Particular attention was paid to technology for energy storage in the form of “renewable” methanol generated from hydrogen produced using renewable surplus energy or from captured CO2. The paper presents a methanol production and treatment plant and a methodology for assessing the plant efficiency. The Electrical Engineering section contains two studies. The first article demonstrates that an electricity- and-power system is affected by various types of power quality disturbances, which have a detrimental effect on generators, transformers and electrical appliances. At the same time, the authors noted that some 6 Scientific Journals of the Maritime University of Szczecin 63 (135) of the most harmful disturbances in power quality are voltage subharmonics, and the study describes the effect of voltage subharmonics on power losses and the heating-up of an induction motor. The second article presents methods for analyzing the power characteristics of generator sets with vector control of an asynchronous squirrel-cage machine. These methods facilitate analyses of the power characteristics of generator sets with field-oriented control (FOC) and direct torque control (DTC). The Mechanical Engineering section also contains two studies. The authors of the first article presented an analysis of possible variants of a handling terminal system by considering the factors of the current development of the Russian transport system. Their considerations were directed at identifying the rationale and possible issues related to the lack of human presence in the technological process of an inland container terminal. The control system of a mini crane is reported in the second study of this section, which analyses a system employing a programmable logic-controlled exoskeleton. The Economics, Management and Quality Science section presents three articles. The first examines the impact of exchange rate movements on international trade. The authors point out that various studies prove that the impact may vary between different sectors and countries. In the fishing industry, this relationship was not widely studied; therefore, an analysis was undertaken in this respect. Using the Emirmahmutoğlu and Köse causality test, the authors examined whether exchange rate fluctuations in certain countries affected fish production. The authors of the next study considered the most important problem in recent months, COVID-19. As we have already seen, the pandemic is a strong determinant, not only of social life, but the economy as well. Recognizing the strong impact of COVID-19 on different spheres of our lives, the authors analyzed the impact of the coronavirus pandemic on the oil market. The authors of the third study in this section, assuming that the management process analysis allows the detection of weaknesses and strengths, analyzed the production line management processes. To this end, they created a queuing model for a production line and analyzed its performance and reliability. The attempted modelling was used to determine whether queuing theory can be used to mod-el processes in production lines. In the last section, Information and Communication Technology, the authors evaluated the tracking performance of the GOOSE platform and compared it to a reference receiver. The quality and performance were analyzed using raw measurements of three signals, GPS L1CA, L2CM and L5. The data were processed with the “zeroEdit” module of the TUB-NavSolutions software. In conclusion, the presented articles address a wide range of contemporary problems that can initiate theoretical and empirical scientific research. We are aware that the problems are described only to a modest extent, yet we hope that the articles will inspire further research and considerations.

This study was designed to determine the vibroactivity parameters of a hermetic harmonic drive. A specially-prepared test bench was used to measure the normal velocity of vibrations and acoustic pressure generated by the unit. Piezoelectric sensors were applied to measure the characteristic values on the body of the prototype. In selected sections of drive, we determined the effective values of acceleration ae and frequency f. For the same points, the effective values of vibration velocity Vc were determined for the corresponding frequencies. The findings presented in this paper enable the assessment of a toothed gear in terms of the quality of its workmanship and wear-related deterioration, which are very important due to the characteristic work of this special drive

This article presents joining methods (welding and sealing) of single-polymer composite materials in a hot air stream. The research material was created using the film-stacking method, which involves pressing successive fractions of polyethylene terephthalate-modified with glycol (PET-G) at defined technological conditions, such as pressure, temperature, and time. Joining method analysis was carried out based on the tensile test results. Analysis of the obtained results showed that the properties of the overlapped weld joint were the best because they were closest to the original materials. In contrast, PET-G welded joint properties were the worst because the PET-G welded joint does not contain fibers, which enhanced the weld; therefore, the fastest breakage of the material was observed at the welding location. For the overlapped weld, the weld itself is more resistant because the joint surface is influenced by friction forces between joined materials.

The GOOSE (GNSS Receiver with open software interface) Software-Defined Receiver has been developed at the Fraunhofer Institute for Integrated Circuits (IIS) in Nürnberg, Germany. The main motivation for the development of this platform was to control the receiver at all stages, from digital signal processing to the PVT domain, and to enable controlled feedback to the hardware. Besides having access to all raw data including correlation values, the GOOSE receiver also enables for example tight- or ultra-tight integration with an inertial navigation system or other dead reckoning systems, as these kinds of architectures require access to the acquisition and tracking loops. In this paper, the tracking performance of the GOOSE platform was evaluated and compared to a reference receiver (Septentrio PolaRx5S). Several long data sessions were recorded on a “zero baseline” in which both receivers used the same precise geodetic antenna that was also developed at Fraunhofer IIS. The measurements were performed in a harsh environment (obstructions, multipath, possible interferences), as well as on a site with an unobstructed sky view. Quality and performance analyses were performed using raw measurements (in the domain of primary observables) of three civil GPS signals: L1CA, L2CM, and L5. The data were processed using the “zeroEdit” module of the TUB-NavSolutions academic software for education and research. The quality of the raw observables and tracking performance were described by the following parameters: number of cycle slips detected, number of un-correctable cycle slips, number of loss of locks of the signals, number of single epoch data gaps, and the length of carrier phase arcs. The presentation is illustrated with some numerical examples.

The article presents the analysis of options for a transshipment terminal system with consideration of Russian transport system development. The aim is to determine the premises and possible problems, considering human absence, in the technological process at an inland container terminal. Statistical methods are used to analyze the market of robotic automation and the perspective for unmanned technology introduction. Simulation modeling of inland container terminal operation with various types of equipment, to study the applicability of robotic automation. The choice of modeling equipment results from the impossibility of completing an experiment on the real object, difficulties of analytical modeling (the system contains casual relations, nonlinear logic, stochastic variables), and the necessity to analyze the system’s time behavior. Consideration of robotic automation in a terminal warehouse complex is of particular importance due to technological progress followed by the freight terminal to be an area with highly organized technological processes and the need for highly paid specialists.

This paper deals with the effect of voltage subharmonics on power losses and heating of an induction motor. An increase in power losses in stator and rotor windings and their impact on windings temperature is presented for subharmonics of various frequencies. The results of this study’s investigations are provided for subharmonics occurring as a single power quality disturbance and combined with voltage deviation. The appropriate electromagnetic computations were performed with the finite element method, and thermal ones – with an analytical method.

The paper presents technologies currently being developed for methanol production and its applications. Particular attention was paid to energy storage technology in the form of “renewable” methanol, which is produced from hydrogen generated from surplus energy from renewable energy sources and from captured CO2. The global methanol market was characterized, i.e. global demand, major producers and global demand for products made from methanol. The installation of methanol production and purification with stoichiometry as well as the methodology for assessing the efficiency of such an installation are also presented. The results of the analysis of such an installation were discussed in accordance with the methodology given.

At the beginning of the COVID-19 coronavirus global pandemic, the oil market was crushed. In this period, the oil market was correlated with COVID-19 coronavirus world infection cases: more infected cases resulted in low oil prices, and the negative correlation between these two indices was very strong. Different factors determined the increase in both crude oil price and the number of oil futures contracts after April 20. Firstly, oil prices were driven by the coronavirus mortality rate, rather than by the absolute number of infection cases. The decisive driver for oil prices in the medium-term became pandemic development trends, instead of the actual epidemiological situation. This statement is proven by the statistical regression model of the interdependence between oil prices and COVID-19 coronavirus world mortality rate. Secondly, a gradual stable decrease in the coronavirus world mortality rate created an environment for the gradual restart of the world economy. Thirdly, the coronavirus mortality rate analysis provides investors with tangible guidelines to assess the medium-term sustainability of futures markets and, therefore, to elaborate investment strategies. Fourthly, after April 20, the oil market gradually achieved equilibrium, which is proven by a restored correlation between oil prices and the Euro-to-U.S. Dollar exchange rate. Three-month tendencies provide tangible guidelines for an optimistic forecast of the oil the market and maritime tanker business for the end of 2020 and all of 2021. So long as a new wave of COVID-19 does not dramatically increase mortality rates, the oil and maritime tanker trade market will regain the equilibrium it lost at the end of January.

This study proposes a new methodology for the accurate risk assessment of railway freight wagons that has real-world applications in the operation and maintenance of freight vehicles. The paper specifically focuses on the analysis of posterior reliability calculation methods using Weibull’s reliability model to calculate reliability indicators by which the probability of occurrence of individual failures can be estimated. The consequences of failure are calculated through an existing system from the General contract used for freight wagons (AVV). The formula for calculating the risk value is based on a classical risk theory, where the risk is defined as a combination of the occurrence of a negative phenomenon and the severity of its consequence. The reasoning for this approach was in an effort to maintain simplicity and clarity for potential users in practice. This is based on the information gathered in examining the current state of risk management in the sector of railway vehicles in Slovakia. The data used for risk calculations were taken from a maintenance workshop in Slovakia to provide a realistic picture of the failure rates of freight wagons. The proposed methodology uses historical data for prediction of reliability for the next years. Based on the reliability being a function of time, the risk associated with it is variable, increasing with time. These findings have broader implications for the maintenance systems taken appropriate maintenance actions necessary with respect to increased risk.