This study evaluates the quantitative effects of laser cladding technology on the refurbishment of valve cages and exhaust valves in a Deutz TBD645 internal combustion engine. Laser powder cladding with Inconel 625 alloy is applied to GGG40 cast iron, and process parameters are optimized to minimize Fe dilution. The method enables low dilution, a homogeneous crack-free microstructure, reproducible valve seat geometry, and stable surface roughness after machining. Quantitative results indicate that laser cladding reduces unit repair costs by 70–80%, while total overhaul expenses decrease by 40–60%. For exhaust valve refurbishment, yearly savings of EUR 125,000–200,000 are achievable for fleets repairing 50–80 components per year. Despite process costs of EUR 250–383/kg, economic benefits remain strongly positive due to reduced downtime and extended component lifetime. The results confirm that laser cladding is an effective method for marine engine overhauls, delivering measurable economic benefits and supporting circular economy objectives in line with IMO 2030 and EU Green Deal targets.

This article presents simulation scenarios that enable a reduction in the rolling surface wear of independently rotating wheels of a four-axle traction vehicle on a curved track with a small radius of curvature. Based on current knowledge, a simulation model of a light four-axle traction vehicle with independently rotating wheels driven by asynchronous AC traction motors is constructed. Kalker’s nonlinear theory is used to describe the contact between the wheels and the rails. The operation of the electric traction motors is controlled using the PWM method. The influence of the stiffness of the first-stage suspension in the vehicle on the wear of individual wheels of the vehicle model is analyzed. It is shown that it is possible to simulate the magnitude of the driving torques acting on individual wheels of the vehicle model, ensuring the reduction of the wear process of the rolling surface of the vehicle wheels on a curved track. Information on the magnitude of these torques could be used to control the movement of the real vehicle

Dear Readers, you hold in your hands the last issue of the quarterly in 2025 (No. 84), concluding another year of our publishing activity. The articles collected in it address contemporary and diverse research issues, reflecting contemporary technological, organisational, legal and environmental challenges, and demonstrating the interdisciplinary nature of the research carried out, relevant to both science and business practices. The current issue features papers on safety and reliability, including risk analyses of hydrogen infrastructure, state-of-the-art radiation monitoring systems using machine learning methods and human reliability issues in industrial maintenance. Articles in the field of mechanical and materials engineering are also an important part of the issue, presenting tests on structural components and the evaluation of the properties of aluminium alloys for marine applications. Transport, logistics and legal issues are also prominently featured, including paid parking zones, pedestrian safety, the reliability of supply chains operating under uncertainty and the transport of dangerous goods in light of international maritime law regulations. Additionally, this issue discusses studies on offshore wind energy development in Poland and modern control algorithms for ship generators. As we close the year 2025, I would like to wish you a splendid 2026, prosperity in your research and professional plans, satisfaction with the challenges you face and further scientific success in the coming year. I hope that this issue will inspire further research and scholarly discussion. I would like to thank the authors and reviewers for their contribution to the high level of the publication. With regards, Editor-in-Chief dr inż. Paweł Prajzendanc

Analyzing available literature, both scientific and commercial, the lack of a simple and quick methodology for determining the dimensions of sailing yachts might be noticed. This method could be used to accelerate the optimal design of modern sailing yachts. When a sailing yacht is designed, many factors need to be taken into consideration, e.g., autonomy, number of crew members, limitations of road transportation, construction and operating costs, yacht speed, and safety of navigation (stability and seaworthiness). Based on the analysis of these criteria, the main dimensions of the yacht need to be determined. In order to quickly select the most optimal type of yacht that will meet the expectations of the customer, several or a dozen variants of the yacht size should be made. Approximate functions are necessary to quickly determine the calculated coefficients depending on the length of the waterline of the hull. The dimensions of the sailing yacht and its coefficients have a decisive influence on the speed of the yacht. The methodological approach used in this article is to use a quick and easy-to-use regression method to present an analysis of the design dimensions and coefficients of a classic sailing yacht. Sailing yachts’ data of 35 similar yachts built between 2010 and 2019 were collected. The overall length range from 6.93 to 21.8 m and the obtained results, without loss of accuracy, are interpolated within the range. The main contribution of this article is to develop simple regression equations to calculate the main dimensions and coefficients of a sailing yacht in many variants without unnecessary delay. These can be used by yacht designers and other people interested in yacht design.

This paper presents a numerical approach to evaluating ship waterplane hydrostatic parameters. The analysis focuses mainly on determining the longitudinal moment of inertia, computed relative to both the aft perpendicular and the midship section. This study is performed for a 9000 DWT general cargo ship with a design draught of 7.5 m. The results show small differences in the longitudinal moment of inertia (IL), which subsequently affect the moment-to-change trim (MTC). However, the study demonstrates that these differences, resulting from the selected point of origin, have a negligible impact on trim calculations. Despite minor mathematical discrepancies, their overall effect is insignificant, with IL deviations within ±0.1%, confirming that these variations do not influence practical trim calculations.

The subject of this paper is to discuss and analyze the noise-induced hazards on ships. For this purpose, factors such as noise levels in different accommodations during various engine operations, methods of protecting crews from the harmful effects of noise, and the impact of noise on health and work are examined. Noise level tests are conducted at different locations on the vessel using a sound meter. Subsequently, a statistical analysis of the obtained results is carried out and the main statistical characteristics are determined and interpreted. The conducted research demonstrates in which rooms the standards are met, where they are exceeded, and in which areas hearing protection should be used. The results could be utilized in future research on occupational health and safety

One of the main operational tasks of fire investigation units is to extinguish fires, which is most often achieved by applying various types of extinguishing agents to the burning material. For firefighting to be effective, it is essential to use appropriate equipment, including fire hoses through which water or water-based solutions are transported. Fire hoses must be resistant to mechanical, thermal, and chemical exposures. In particular, they must withstand abrasion, which can compromise tightness and result in leakage or uncontrolled water jets. Hose webbing typically has a multilayer structure. The outer (surface) layer is exposed to abrasion from sliding friction in contact with rough surfaces, sometimes containing abrasive particles. Abrasion against sharp edges occurs less frequently due to safety features such as fire hose saddles. Pilot laboratory tests were carried out on the hose webbing of four fire hose models to determine the coefficient of friction and linear wear. Additionally, observations were made on the wear mechanisms affecting the hose webbing surfaces.

The success of a search and rescue operation at sea depends on accurately determining the location and search area of a drifting pneumatic life raft, with particular emphasis on drift. This article examines the leeway of pneumatic life rafts and provides a summary of the available types used as life-saving appliances on ships. Based on experimental and numerical studies, the technical characteristics of the life rafts were compared, and the relationship between their shape and leeway components was analyzed. The research demonstrated the degree of dependence between the life raft’s shape and its aerodynamic and hydrodynamic drag. The results obtained are significant and will inform further numerical studies on leeway and search area estimation. The authors’ previous experimental and numerical work, as well as findings from earlier publications, form the basis for the calculations presented in this paper.

Intermodal transport is a key element of the Trans-European Transport Network (TEN-T), and containers are among the most commonly used cargo units in this system. This study aims to examine the development trends in container handling at intermodal terminals in Poland. The results of the study indicate continued dynamic growth in this sector, supported by European Union policy, infrastructure investments, and the expansion and construction of new container terminals, as well as the activities of logistics companies and intermodal carriers. Projects co-financed by EU funds also play an important role, providing an additional stimulus for development.

Abstract This article addresses the problem of sensorless control of a squirrel-cage induction generator (SCIG) used as a shaft generator in shipboard DC power systems. The work is motivated by the growing adoption of DC ship- board microgrids, where robust and cost-effective generators without mechanical sensors are desirable. A math- ematical model of the SCIG in α-β and d-q reference frames is derived and discretized, enabling efficient re- al-time implementation on a DSP–FPGA control platform. Building on this model, the paper proposes a hybrid current–voltage observer that combines a current-model estimator (effective at low speed) with a voltage-model estimator (accurate at medium and high speed). PI-based compensating voltages are introduced to suppress numerical integration drift and reduce sensitivity to stator resistance variation, ensuring accurate estimation of rotor flux, flux angle, and rotational speed. The excitation process of the generator is analysed with respect to initial DC-link voltage, shaft speed, and loss currents, and criteria for successful self-excitation are identified. The proposed algorithm is validated through time-domain simulations and laboratory experiments on a 3 kW SCIG system. Results show close agreement between simulation and measurements, stable DC-link voltage regulation under varying load and speed, and reliable sensorless operation that is comparable to, or more robust than, encoder-based systems in the presence of EMI. The study confirms the practical suitability of the hybrid observer for shipboard SCIG applications over a wide rotational speed operating range.

Faced with the European Union’s growing expectations regarding the intensification of energy generation from renewable sources, Poland, like many other European countries, has encountered the enormous challenge of introducing energy produced by offshore wind farms (OWFs) into the energy market. This article aims to present the current state of development of offshore wind farms (OWFs) in Poland and to identify the main opportunities and threats associated with the further development of this sector in the domestic and international context. The direction of the current rapid investment growth in this area stems from decisions of the European Parliament and the European Council, which require intensified efforts to increase the share of energy obtained from renewable sources in the energy mix. At the same time, the creation of an energy base in the form of offshore wind farms in Poland contributes to energy diversification and improves the country’s energy security. Several projects are currently underway in the Polish Baltic Economic Zone, the largest of which include Baltica 2 and Baltica 3, led by PGE Polska Grupa Energetyczna and the Danish company Ørsted. The construction of offshore wind farms encounters several barriers that hinder project implementation; however, long-term energy production can bring numerous benefits to Poland. This paper highlights the key advantages of offshore wind farm development, including Poland’s energy sovereignty, job creation, and strengthened efforts to reduce greenhouse gas emissions. The greatest threats, however, include an underdeveloped local supply chain, unpredictable legislative changes, and the risk of delays due to environmental requirements. Considering the limitations associated with the lack of production continuity and the ability to fully utilize the electricity generated by offshore wind farms, solutions for industrial-scale electricity storage are presented, including conversion to compressed air using compressed air energy storage (CAES) technology, and the conversion of electricity into chemical energy in the form of hydrogen (H2).

The main objective of this article is to demonstrate the impact of uncertainty on the resilience of supply chains. To achieve this task, a theoretical discourse is presented on both uncertainty and supply chain resilience. A survey is conducted among 160 supply chain managers and directors from around the world. The survey utilized the computer-assisted web interview (CAWI) method, and the results are analyzed using the Ward agglomeration method. The findings enabled a determination of the strength of uncertainty’s impact on supply chain resilience, understood through the so-called 4A formula, which combines flexibility, adaptability, resilience, and alignment. Additionally, the article discusses whether these considerations can contribute to supply chain management, particularly in supporting decision-making processes, such as the supply chain’s response to uncertainty. This study is the author’s original work and represents their contribution to the ongoing scientific discussion on the resilience (including response) of supply chains under conditions of uncertainty.

In Poland, the introduction of absolute priority for pedestrians at crosswalks in traffic regulations may increase the number of accidents. Improved traffic control of intersecting routes may be a more effective solution. The recent amendment to the law overlooks the fact that a moving vehicle cannot stop immediately. The dynamics of vehicle stopping, especially before a pedestrian crossing, must be taken into account. This article analyzes possible road scenarios encountered when approaching a pedestrian crossing. Pedestrians at crosswalks should be safe and protected. While granting pedestrians the right of way is an ideal scenario, certain situations may still pose risks to their safety. Proposed solutions to reduce the risk of accidents for pedestrians entering the crossing are also included. The introduction of appropriate signaling, along with a selected algorithm and sensors, can help alleviate the danger to pedestrians. Additionally, the system should identify when a bus is approaching the pedestrian crossing and monitor adverse weather conditions that reduce a vehicle’s ability to stop abruptly

This study aims to determine the effect of loading on stress distribution in components of the scissor lift during the pushing up or down of the car being analyzed. The FEM models of the lead screw and the lift arms are elaborated and implemented using both Autodesk Inventor and the Solid Edge software. The mathematical model for the lead screw is also developed. The models allowed for the obtaining of the von Mises stress values in the lead screw and in the lift arms. Such stress values in the middle of the FEM screw model coincided with those determined analytically. The obtained values are very sensitive to the level of refinement applied for the size of finite elements. The values of the von Mises stresses in both lower and upper arms varied depending on the lift. For a small value of the lift, they can be up to 35% higher than those in the lead screw. However, for the higher lift, the von Mises stress values in the arms may be equal to or smaller than those in the lead screw.

In an era of constantly changing needs and challenges posed by urban stakeholders and an increasing number of vehicles in the area, transport accessibility has started to play a key role. Shaping transport infrastructure in cities is one of the greatest challenges city managers have. In recent years, the introduction of paid parking zones (PPZs) has become an increasingly common solution. This paper aims to assess the impact of parking fees on the mode choice of users of urban spaces. As part of the research process, a systematic review of literature in the area outlined above and an analysis of transport accessibility in the selected area are carried out. This paper presents the results of a survey on the determinants of transport mode choices in the city of Szczecin. The results show that, despite high rates imposed by city authorities, users of urban spaces still choose to travel by car to their destinations and that parking fees do not have a real impact on modal shift. These results offer valuable insights for both drivers and local authorities in terms of creating transport accessibility for the final stage of this journey ‒ i.e., parking accessibility.