Scientific Journal of Gdynia Maritime University

The problems related to advancements in signal processing, mathematical tools and new analysis methods applied in investigations into different industrial fields have been intensively explored over the last few years. This issue of the Scientific Journal of Gdynia Maritime University is addressed to widely treated problems occurring in the newly defined disciplines of science: automation, electronic, electrical engineering and space technology, as well as mechanical engineering, navigational and maritime transport, and management and quality studies. The issue comprises six research papers specifically dedicated to the subject: miniature circuit breaker time-current characteristic (1), analysis of the operation of a type AC RCD (2), thrust characteristics and propulsive efficiency in a biomimetic underwater vehicle (3), preliminary second-hand ship price estimation (4), simulation and stochastic spatial optimization of the sausage resting process (5), and intra-terminal efficiency analysis of container terminals at JNPA (6).

Paper 1 presents the outcome of miniature circuit breaker (MCB) time-current curve measurements for non-sinusoidal current. The outcome of the conducted tests indicate that MCBs show some differences in operation in the case of non-sinusoidal current flow. The achieved results indicate the current waveform impact on circuit breaker operation, specifically on its time-delay overcurrent element.

Paper 2 deals with an analysis of the operation of a type of AC RCD, protecting a circuit in which a nonlinear load is connected. It was concluded that AC type RCDs are sensitive to current deformations in the leakage circuit. The experimental data presented were analyzed, and the final conclusions were drawn.

Paper 3 is devoted to the development and experimental investigation of the Nerpa unmanned underwater vehicle, equipped with a biomimetic propulsion system based on undulating fins. The study highlights the advantages of this solution over conventional propeller-driven systems, particularly reduced hydroacoustic noise, improved maneuverability, and effective depth control. The research contributes to the development of stealthier unmanned underwater systems for marine infrastructure inspection and monitoring.

Paper 4, “Applying Multilayer Perceptron and Data Filtering for Preliminary Second-hand Ship Price Estimation”, presents an analysis of the prediction of prices related second-hand vessels. The analysis focuses on bulk-carries and tankers, and the relationship between deadweight tonnage and sale prices. The author uses a Multilayer Perceptron neural network, applying Z-score outlier filtering to the data processing. This approach, and machine learning methods in general, can be effectively applied to forecasting selling prices, which, as the author notes, helps reduce prediction errors.

Paper 5 focuses on optimizing logistics during the pre-smoking holding stage in sausage production, with particular attention to reducing delays and their impact on product quality and production efficiency. The study develops a simplified model of smoking trolley movement and positioning and proposes a stochastic optimization algorithm to reduce unnecessary operator travel and process delays. The results support improved production planning and automation in meat-processing facilities.

Paper 6, “Intra-Terminal Efficiency Analysis of Container Terminals at JNPA Using Data Envelopment Analysis”, addresses container terminal efficiency and its role in port competitiveness. The authors analyze the number of vessels handled, terminal area and the number of quay cranes as input parameters, and container throughput as output, applying Data Envelopment Analysis (DEA) to five terminals within India's leading container port. The proposed analysis can also be used as a methodological framework by other port authorities to improve operational efficiency and benchmark results.

Janusz Mindykowski

Robert Starosta

Agnieszka Blokus-Dziula

Agnieszka Rybowska