The results of finite element analysis of large machined rotor fastened into heavy precise lathe are reported. Many design changes are simulated to improve the dynamic rigidity of the machining. Three radial eigenmodes detrimental to the accuracy were revealed: rotor-stock bending at 17.7 Hz (“half-wave”), rotor-lathe bending at 36.1 Hz (“full-wave”), and “support rocking” at 68.1 Hz. The frequency response functions and dynamic rigidities were evaluated. Three compliance issues were revealed: angular flexibility of the spindle console, low stiffness of the lathe bed (with boots), and an excessively slender tailstock. It is proposed to transform the spindle chuck into a table with additional hydrostatic backing, fill the bed cavities with concrete, and redesign the tailstock as a counter-spindle unit. This will decrease the amplitude of the main rotor resonance by 6.3 times and upshift the frequency near two-fold from 17.7 to 35 Hz. The renovated lathe should be able to machine a rotor without a lunette system or overriding the main resonant frequency.

Dear Readers, We are pleased to present this year’s first issue (No. 65) of the Scientific Journals of the Maritime University of Szczecin. This year will bring many new challenges, also for the journal, where we continually focus on improved quality. We would like to thank the authors, reviewers and readers for their contribution to our journal. I hope that we will continue to develop this path together. This issue presents the research results and authors’ views in seven articles organized into three thematic sections: Civil Engineering and Transport, Mechanical Engineering, and Economics, Management and Quality Science. The Civil Engineering and Transport section features two articles. The first article presents an analysis of internal forces and roll motion during a nodule loading simulation for a ship at sea. The study carried out a full assessment of a ship’s behaviour during loading, which took into account wave height and period around the Clarion–Clipperton Zone by the use of an operational efficiency index. The second article addresses the International Convention for the Safety of Life at Sea (SOLAS). The Convention aims to improve the safety of life at sea by laying down rules and regulations for the construction of ships and providing models for the documents created. The Mechanical Engineering section consists of three articles. In the first article, the authors analysed the special configuration of a multi-role moving-column machining centre by the finite element method. In the second article, a CFD-based numerical approach was developed and applied to a trimaran hull in the presence of regular and irregular waves. According to the authors, the proposed CFD method reduces the simulation time and calculation resources needed to determine a ship’s motion. The third article presents the results of the testing of long-distance heat transfer surfaces in marine diesel engines, including elliptical and flat-oval tubes. The study used mathematical models that involved equations from conservation of energy, equations of motion, continuity and state, where the RSM of turbulence was also used to complete the equation system. The Economics, Management and Quality Science section includes two articles. The first article analyses the factors affecting the performance of VTS operators. Its general conclusion is that the effective work of VTS operators, combined with a specific maritime environment and vessel traffic management support system, are the key determinants for ensuring the reliability and safety of the entire system. The second article’s authors wanted to see if a multi-criteria analysis was appropriate for the evaluation and implementation of energy-efficient mobility in seaports. The multi-criteria model for the selection of the most appropriate energy-efficient mobility solution was tested for two Croatian private marinas. The articles featured in this issue reflect the authors’ theoretical and practical inspirations, contributing to important and state-of-the-art scientific research. We believe that these findings will become the basis for further reflection, discussion, and broader research.

A holistic approach and stakeholder consultation are necessary before implementing a particular city logistics measure. The need to implement sustainable urban logistics solutions is particularly important in seaports located in cities. Such cities, particularly Gdynia, have a high intensity of cargo flows resulting from transport connected with their port facilities. The purpose of this article was to identify the level of acceptance of sustainable and innovative urban logistics solutions by entities that use the services of the seaport in Gdynia. We investigated whether the proposed solutions found sufficient acceptance among the respondents, and which of the proposed solutions were the most preferred by stakeholders. We hypothesized that urban logistics solutions were not sufficiently accepted by the stakeholders of the seaport of Gdynia. In order to analyze the awareness of the involved parties, we surveyed parties at the Port of Gdynia as part of the Interreg project called TENTacle. Our findings did not support this hypothesis with respect to such measures as FQP, the use of interactive city maps, night deliveries, and the use of ITS, as these are the solutions most preferred by the stakeholders of Gdynia. The results of this study can therefore serve as an important tool for the city of Gdynia, and similar cities, when preparing sustainable urban logistics plans.

Transport is integral to every city, having a crucial impact on its functioning and development. As road infrastructure does not up to keep up to speed with the constantly growing numbers of vehicles on roads, new solutions are required. Fast urban railway systems are a solution that can reduce transport congestion, with environmental protection issues also taken into account. Following these reasons, the decision was made to build the Szczecin Metropolitan Railway (Szczecińska Kolej Metropolitalna, or SKM), consisting of four lines constructed using existing railway infrastructure, within the Szczecin Metropolitan Area (SMA). The construction works on the linear and point assets of the SKM are ongoing and will be concluded in 2022. Therefore, given the large impact of this project on the affected communities, the purpose of the present study was to analyze the expectations of the SMA population concerning the launch of the SKM via a large-scale questionnaire. For the purposes of the study, the following research hypothesis was defined: from the assessment of the affected residents, the introduction of the SKM will considerably improve the travel experience and greatly facilitate transit within the fast railway system’s area of impact. From the analysis of the questionnaire, it could be concluded that the introduction of the SKM will have a positive impact on the improvement of transport within the Szczecin area and shorten travel times significantly.

This article presents an analysis of internal forces and roll motion during a nodule loading simulation for a ship at sea. The study carried out a full assessment of ship behavior during loading, which took into account wave height and period occurrence around the Clarion–Clipperton Zone by the use of an operational efficiency index. One of the aims was to verify whether waves have an influence on excessive ship motion and internal forces during nodule loading. Two alternative loading sequences were developed and compared by taking loading time, shear forces, bending moments, roll motion and waving into account. The research shows that loading is only possible during specific sea weather conditions for the selected bulk carrier.

Charge air cooling is essential for the efficient operation of marine diesel engines. This work presents the results of research on the characteristics of long-range heat transfer surfaces for marine diesel engines. Elliptical and flat-oval tubes were considered. This study was carried out using mathematical models that consisted of the equations for energy conservation, motion, continuity, and state. The RSM turbulence model was used to close the system of equations. To solve the resulting system of equations, the RANS approach was used, which was implemented in the software package Code Saturne with a free license and the SimScale cloud service. The mathematical model was verified by comparing the model results with the experimental results obtained using a prototype heat-exchange surface of a charge air cooler at a test bench. The discrepancy between the theoretical and experimental heat transfer coefficient α was ≤ 8.3%. An estimate of the compactness of smooth elliptical and flat-oval tube banks compared with round ones was carried out. A 19.6% increase in compactness was obtained for elliptical tubes and 17.5% for flat-oval tubes. Based on the profiled finning surfaces, it is possible to improve their thermohydraulic characteristics by up to 40% when using them together with elliptical tubes compared with round ones and up to 26% when using them with flat-oval tubes.

In Europe, at the end of the 20th century, the growth of marinas followed the rapid development of recreational marine activities. This trend has now slowed and today the creation of new marinas or the extension of existing marinas is less common, mainly due to the enforcement of protective environmental regulations. As the port sector is facing some major sustainability challenges, like tackling the pollution generated from port activities, the “green port”, or “green marina”, concept has now become a requirement. Both types of nautical ports, public ports and private marinas, share the same responsibility to achieve management standards. The term “green port” in practice describes the responsible behavior of all stakeholders in the port’s business, with a focus on the long-term vision towards the sustainable and climate-friendly development of the port’s infrastructure. This paper aims to confirm the adequacy of multi-criteria analysis (MCA) for the evaluation and introduction of energy efficient mobility options in nautical ports. Within the paper, a multi-criteria based model for energy- efficient mobility selection is presented. This model is tested on two Croatian private marinas and obtained results indicating the most suitable action for both. The output of the model showed that by far the best energy- efficient solution was the installation of electric charging stations (ECS) for cars. The presented model can assist decision-makers in port authorities and marina administrations in planning and finding the best scenario for the development of energy efficient systems and services.

Abstract This paper examines the factors affecting the performance of VTS operators. A general review of the human factor as a determinant of navigational safety is presented. The elementary nature of the system and its structure are defined, and the ability of a VTS operator to perform planned tasks within a specified timeframe and in a specific manner is analyzed. A reliability assessment scheme is proposed, which is based on the interpretation of factors affecting the VTS operator’s efficiency. The effective performance of VTS operators, along with the specific nature of the maritime environment and reliability of the vessel traffic management support, are key determinants in the process of ensuring the reliability and security of the entire system.

Presented are regulations concerning the operation of passenger ships (with particular emphasis on Polish ferries) designed to increase maritime safety the SOLAS Convention, established in 1974 and codified in 2002, codifies these regulations, and the International Maritime Organization mandates additional regulations, created in response to a rapidly increasing number of maritime disasters. The analyses described herein were based on restrictions established for the “Jan Śniadecki” and “Mikołaj Kopernik” ferries. Safety of ro-ro units, which also typically have a significant number of people on board, was also analyzed. Also included in the study were ship operational- limitation characteristics with respect to structure, unsinkability, and stability of machinery and electrical equipment, fire protection, operational requirements, and rescue measures and devices, along with their purpuroses. Safety management consists of taking appropriate actions to prevent or minimize the effects of an accident or a disaster and is assessed on the basis of calculations and experience gleaned from analogous cases. Safety management can proceed if a problem has been thoroughly assessed. The potential risk of negative consequences with respect to the safety of the transport process as a whole must be considered, and the safety of the whole must not be risked for that of a particular part of it. A safety management decision can be made when its necessity is not in doubt. A problem is assumed to have only one solution. The effectiveness of the previously used method should be carefully assessed before proceeding to the next method. Security management is not easy and requires much professional knowledge and experience.

In this paper, a special configuration for the huge multipurpose machine tool of “travelling column” type was investigated by the finite element analysis. Internal degrees of freedom of a bulky system consisting of the ram, stock, column, sledge and bed, were implemented by the hydrostatic guides. A simulation of coupling two assembled columns into the portal structure was completed. The results of this work showed that temporal joining raises the spindle static rigidity by 1.39–1.91 times depending on the direction (mostly longitudinal – along the X-axis). The simulation also revealed the robustness of a whole-machine resonance pattern (11.7–39.0 Hz) to “column–to–portal coupling”. Eight types of eigenmodes were analyzed for frequency intervals from 0 to 80 Hz. A decrease by 2.9 times of the resonance peaks of a frequency response function was observed in the case of a portal structure creation. In case of columns-to-portal transition, stable cutting just at resonance frequencies (resonance overriding) becomes allowable. Overall, the “Portal” structure is recommended for intermittent cutting machining by raised high spindle unit at frequencies below 40 Hz.

The hydrodynamic performance of trimaran hulls has been previously investigated for optimum performance in calm water, but there is still a limited understanding of its motion response; therefore, a CFD-based numerical approach was developed and applied on a trimaran hull in the presence of regular and irregular waves. To validate the CFD method, a comparison was conducted using both experimental and 3D panel method data. In this study, two different turbulence models were surveyed, and the SST Menter k-Omega (k-ω) turbulence model was shown to be a more accurate model than the realizable k-Epsilon (k-ε) model. The different features of the proposed numerical model include the implementation of an overset mesh method, unique mesh plan refinement, and wave-damping region. The discrepancy between the experimental data and the results of other seakeeping calculation methods have always been problematic, especially for low-speed strip theory and 3D panel methods, but good consistency was observed between the proposed CFD model and experimental data. Unlike potential-based or conformal mapping seakeeping analysis methods, the effect of nonlinear waves, hull shape above the waterline, and other ship dynamic phenomena were considered in this CFD application. The proposed CFD method reduces the simulation time and computational efforts for ship motion calculations.

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.