<abstract><title style='display:none'>Abstract</title> The article presents an accelerated method for fatigue limit calculation which makes use of constant temperature increase rate observed in the middle time interval of specimen fatigue loading. The examination was performed on specimens prepared from drawn rods made of corrosion resistant austenitic steel X5CrNi18-10 (1.4301) subjected to rotating bending. For comparison purposes, the fatigue limit was also calculated with the aid of the Staircase method, using 30 specimens and assuming the base number of cycles equal to 10·106. Three specimens were used for accelerated examination during which their temperature was measured with the aid of the thermographic camera CEDIP Silver 420M (FLIR SC 5200). The applied loads were gradually increased until specimen damage took place. Based on the analysis of temperature changes during specimen loading, the average rate of temperature increase at successive loading stages was assessed. The obtained results were then approximated using the 2-nd order curve and its minimal value was assumed as corresponding to the fatigue limit. The performed statistic test has revealed that the fatigue limit calculated in the above way does not differ substantially from that determined using the Staircase method.</abstract>

Thermographic Method Based Accelerated Fatigue Limit Calculation for Steel X5CrNi18-10 Subjected to Rotating Bending

<abstract><title style='display:none'>Abstract</title> The study presents two approaches to plotting an S-N curve based on the experimental results. The first approach is commonly used by researchers and presented in detail in many studies and standard documents. The model uses a linear regression whose parameters are estimated by using the least squares method. A staircase method is used for an unlimited fatigue life criterion. The second model combines the S-N curve defined as a straight line and the record of random occurrence of the fatigue limit. A maximum likelihood method is used to estimate the S-N curve parameters. Fatigue data for C45+C steel obtained in the torsional bending test were used to compare the estimated S-N curves. For pseudo-random numbers generated by using the Mersenne Twister algorithm, the estimated S-N curve for 10 experimental results plotted by using the second model, estimates the fatigue life in the scatter band of the factor 3. The result gives good approximation, especially regarding the time required to plot the S-N curve.</abstract>

PhD, University of Science and Technology in Bydgoszcz Al. Prof. S. Kaliskiego 7 85-796 Bydgoszcz,

University of Science and Technology in Bydgoszcz Al. Prof. S. Kaliskiego 7 85-796 Bydgoszcz,

Experimental Method for Plotting S-N Curve with a Small Number of Specimens

<abstract xml:lang="en"><title style='display:none'>The Added Mass Coefficient computation of sphere, ellipsoid and marine propellers using Boundary Element Method</title>Added mass is an important and effective dynamic coefficient in accelerating, non uniform motion as a result of fluid accelerating around a body. It plays an important role, especially in vessel roll motion, control parameters as well as in analyzing the local and global vibration of a vessel and its parts like propellers and rudders. In this article, calculating the Added Mass Coefficient has been examined for a sphere, ellipsoid, marine propeller and hydrofoil; using numerical Boundary Element Method. Since an Ellipsoid and a sphere have simple geometric shapes and the Analytical values of their added mass coefficients are available, so that the results of added mass matrix are obtained and evaluated, using the boundary element method. Then the added mass matrix is computed in a given geometrical and flow specifications for a specific propeller and its results are studied versus experimental results, which it's current numerical data In comparison with other numerical methods has a good conformity with experimental results. The most important advantage of the method in determining the added mass matrix coefficients for the surface and underwater vessels and the marine propellers is extracting all the added mass coefficients with very good Accuracy, while in other numerical methods it is impossible to extract all the coefficients with the Desired Accuracy.</abstract>

The Added Mass Coefficient computation of sphere, ellipsoid and marine propellers using Boundary Element Method

<abstract xml:lang="en"><title style='display:none'>Design analysis of Tesla micro-turbine operating on a low-boiling medium</title>This paper presents results of the design analysis of a Tesla bladeless turbine intended for a co-generating micro-power plant of heat capacity 20 kW, which operates in an organic Rankine cycle on a low-boiling medium. Numerical calculations of flow in several Tesla turbine models were performed for a range of design parameters. Results of investigations exhibit interesting features in the distribution of flow parameters within the turbine interdisk space. The calculated flow efficiency of the investigated Tesla turbine models show that the best obtained solutions can be competitive as compared with classical small bladed turbines.</abstract>

Design analysis of Tesla micro-turbine operating on a low-boiling medium

<abstract xml:lang="en"><title style='display:none'>Conceptual Design and Performance Analysis of an Exhaust Gas Waste Heat Recovery System for a 10000TEU Container Ship</title>According to operation characteristics of the main engine 9K98ME-C7, a combined turbines-exhaust gas waste heat recovery system is proposed to recover waste heat and increase system energy efficiency. Thermodynamic models based on the first thermodynamic law and the second thermodynamic law are formulated. The superheated steam yield, the total electric power yield, the first thermodynamic law efficiency, the exergy efficiency at different exhaust gas boiler working pressure, and the variation of the exergy efficiency under different feed water temperature and different steam turbine back pressure are analyzed. Thermodynamic results indicate that the most appropriate exhaust gas boiler pressure is 0.8MPa for studied main engine and the total thermal efficiency with combined turbines arrangement has climbed up to 53.8% from 48.5%.</abstract>

Conceptual Design and Performance Analysis of an Exhaust Gas Waste Heat Recovery System for a 10000TEU Container Ship

<abstract><title style='display:none'>ABSTRACT</title>Labyrinth seals are essential components of steam turbine unit constructions. Two types of labyrinth seals can be named, the first of which is the seal without diagnostic steam extraction, and the second - with extraction. The distribution of flow parameters along the packing is affected remarkably by the average seal clearance. The presence of diagnostic extraction leads to the equation system which is determinable and can be inversed to calculate the average seal clearance Si. Analysing the obtained results leads to the conclusion that the information about this parameter provides opportunities to monitor the current state of the packing in real time. The applied calculation procedure bases on the de Saint - Venant equation. The article also includes a brief description of both types of seals.</abstract>

Calculations of labyrinth seals with and without diagnostic extraction in fluid-flow machines

<abstract>
<title style='display:none'>Abstract</title>
The main goal in the design phase is to create a safe ship with a very efficient (and preferably zero-emission) propulsion system. To obtain such ships, new concepts are being developed for both propulsion systems and individual components. The choice of a propulsion system is not straightforward. To optimise the selection of the propulsion system, it is valuable to optimise the energy demand of this unit, which can be done by creating operational movement profiles that indicate the differences in energy demand needed to cover the same route within similar times. Optimisation can be performed based on many different criteria, especially for crowded waterways, and can not only reduce the amount of energy needed to power the propulsion system but also increase navigational safety. In this work, optimisation is carried out by searching the space of all possible solutions, which allows for an in-depth analysis according to various criteria.
</abstract>

Optimisation of the Energy Consumption of a Small Passenger Ferry with Hybrid Propulsion

<abstract>
<title style='display:none'>Abstract</title>
Compass errors can be regarded as a deviation of the vessel from the expected heading. Gyrocompass errors are randomly oscillating in nature, and it is difficult to describe the behaviour of a gyrocompass sufficiently accurately using mathematical relationships. Fibre-optic gyroscopes have no mechanical components, so the variability in their indications has a different nature; the computational processes and inertial sensors used cause certain types of errors. Thus far, compass studies have focused on presenting absolute errors in the time domain. However, compasses exhibit specific characteristics in the frequency domain that affect the amplitude of their deviation. This leads to the issue of identifying the oscillatory spectrum of errors in the operation of such compasses, and how this spectrum is impacted by the dynamic movement of the vessel. We attempt to assess this phenomenon by means of measurements taken on board the training and research vessel M/S NAWIGATOR XXI. The application of a fast Fourier transform allows for calculation of the absolute compass errors in the frequency domain, meaning that the frequency of occurrence of errors can be observed as noise against the background of the useful signal. Our results confirm the value of applying a finite impulse response filter, which is used to filter out noise in the form of absolute compass errors from the useful signal background. The convolution function proposed here considerably extends the possibilities for analysing the signal spectrum in the frequency domain when testing for the accuracy of compass device indications, and enables the elimination of random errors with a low frequency of occurrence..
</abstract>

Spectral Analysis of Compass Errors Based on Fast Fourier Transform and Reduction Absolute Errors Using a Pass-Band Finite Impulse Response Filter

<abstract>
<title style='display:none'>Abstract</title>
With each passing day, maritime organisations are equipped with more technology, and these systems form a structure that creates international networks. Digitalisation will have implications and effects on value creation, business models, horizontal and vertical integration, services and work organisation. While digital technologies in the maritime sector reduce risks owing to transparency, adaptability, traceability, flexibility and scalability, can also give discernible improvements in terms of operational processes, cost reductions, etc.. In the developing maritime sector, there are a variety of digital technology-related challenges that remain to be overcome, but there is no structured overview of the main types of challenges/barriers encountered by specialists. In this study, we explore the challenges/barriers to digitalisation in the maritime sector and how these are perceived by employees in this sector. The aim of our research is to identify these challenges/barriers and understand the relationships between them. To categorise the challenges/barriers, the DEMATEL approach was used. As a result of the analysis, it is seen that the main hindrances to digitalisation in the maritime sector are the problems of complexity, integration and interoperability. In contrast, the difficulties of performance appraisal and scalability emerge as the least important issues affecting the implementation of digital technologies in this area. Our results indicate that economic problems exert a significant causal influence on the other challenges/barriers.
</abstract>

Are We Ready for Digitalisation? A Study of the Challenges and Barriers to Digitalisation and Technology Use in the Turkish Maritime Sector

<abstract>
<title style='display:none'>Abstract</title>
Since the International Maritime Organization has paved the way towards zero emissions, more frequent applications of transition fuels in newly constructed ships have been observed. Fuels such as LNG or methanol are characterised by lower emissions when burned in engines. In order to diminish fuel consumption, and hence the rate of emission, support for the performance of a ship’s engines with energy from renewable sources such as photovoltaic (PV) installations is increasingly common. The efficiency of PV panels decreases with an increase in temperature, and it is therefore important to cool them. However, the cooling systems for PV panels impose additional financial outlays as well as a higher demand for electric power, which is needed to run the circulating pumps. A natural cooling process can occur in some vessels via high sea waves, when the ship’s decks are flooded by outboard water, although such cooling has an accidental and periodic character, as it results from weather conditions. Despite this, its potential demands a closer examination. This paper presents experimental research carried out with an experimental setup that allowed us to simulate the process of flooding of a PV panel with water waves of various frequencies, resulting from choppy periods at sea. Depending on the weather conditions and the character of flooding, our results indicate that an increase in the power of the PV module of about 18% is obtainable. Our research shows that when the intervals between flooding are longer, the periodic character of the temperature changes obtained by flooding the front surface of a PV panel with water is more distinctive.
</abstract>

Effect of Overflowing by Seawater on the Power of a Ship’s Photovoltaic Panels under Extensive Sea Waves

<abstract>
<title style='display:none'>Abstract</title>
Low-power, small-size, unoccupied devices are often used in the ocean. However, the requirements for long-distance operation and long-term, high-power supplies have always been difficult technical problems to solve. Wave energy can be effectively used to meet the requirements of a high power supply. Based on a comprehensive analysis of the shortcomings of existing wave energy converters, we present an innovative design for a novel hydraulic flexible wave energy mobile power system and its internal structure. The dynamic model is then simplified into a double-float system, with a spring force from a flexible liquid bag on the upper and lower floating bodies. Furthermore, a model is developed to assess the energy efficiency of the double floating body, and the energy supply strategy and the posture of the double-float system are investigated. The hydrodynamic parameters of three typical axisymmetric rotary floating bodies are analysed using AQWA software, and it is found that the hemispheric-bottomed cylinder (HBC) exhibits superior energy efficiency under the same conditions of space, mass, and drainage volume. Its energy efficiency is mainly reflected in its ability to capture the wave frequency and wave width. HBC floaters perform optimally in both respects. The stability of our design is analysed, and a mathematical relationship between the centroid G and the centre O of the HBC model is developed. The stability of the model is then studied. This study provides a theoretical basis for the provision of low-power, compact, unmanned maritime equipment.
</abstract>

Optimisation of Double Floating Bodies for Small Unmanned Marine Devices Based on a New Hydraulic Flexible WEMP System

<abstract>
<title style='display:none'>Abstract</title>
In this project, an innovative wind turbine was designed for a floating plant. A large Savonius rotor was replaced with a double-rotor wind turbine implemented as a horizontal-axis turbine. This double rotor was positioned on the tip of a thrust plate and fixed to the deck of a catamaran. Simple 2D numerical simulations were performed to confirm the effectiveness of the concept. An analysis of the floating system configuration was carried out, and the loads and stresses on the system components were verified. Next, floating supports with appropriate sizes were selected to counteract the forces on the wind turbine system. Finally, an anchoring system with full rotational freedom was selected for the floating platform. The present work was conducted as part of a Master’s thesis.
</abstract>

An Innovative Floating System with a Savonius Rotor as a Horizontal-Axis Wind Turbine

<abstract><title style='display:none'>Abstract</title> Ship stowage plan is the management connection of quae crane scheduling and yard crane scheduling. The quality of ship stowage plan affects the productivity greatly. Previous studies mainly focuses on solving stowage planning problem with online searching algorithm, efficiency of which is significantly affected by case size. In this study, a Deep Q-Learning Network (DQN) is proposed to solve ship stowage planning problem. With DQN, massive calculation and training is done in pre-training stage, while in application stage stowage plan can be made in seconds. To formulate network input, decision factors are analyzed to compose feature vector of stowage plan. States subject to constraints, available action and reward function of Q-value are designed. With these information and design, an 8-layer DQN is formulated with an evaluation function of mean square error is composed to learn stowage planning. At the end of this study, several production cases are solved with proposed DQN to validate the effectiveness and generalization ability. Result shows a good availability of DQN to solve ship stowage planning problem.</abstract>

A Deep Q-Learning Network for Ship Stowage Planning Problem

<abstract><title style='display:none'>Abstract</title> The path following control problem of the underactuated unmanned surface vessel (USV) is studied in this paper. An improved line-of-sight (LOS) guidance algorithm is proposed which can adjust adaptively based on the path following error. The global asymptotically stable path following controller is designed based on the nonlinear backstepping method and the Lyapunov stability theory. Firstly, the USV path following error model is established in the Serret-Frenet (SF) coordinate frame. The path following error in the inertial coordinate frame is transformed into the SF coordinate frame, which is used to define the path following control problem. Secondly, inspired by the traditional LOS guidance algorithm, the longitudinal path following error in the SF coordinate frame is introduced into the improved LOS guidance algorithm. This allows the algorithm to adjust adaptively to the desired path. Thirdly, in order to solve the underactuated problem of the USV path following control system, the tangential velocity of the desired path is designed as a virtual input. The underactuated problem is converted to a virtual fully actuated problem by designing the virtual control law for the tangential velocity. Finally, by combining backstepping design principles and the Lyapunov stability theory, the longitudinal thrust control law and the yaw torque control law are designed for the underactuated USV. Meanwhile, the global asymptotic stability of the path following error is proved. Simulation experiments demonstrate the effectiveness and reliability of the improved LOS guidance algorithm and the path following controller.</abstract>

College of Automation, Harbin Engineering University,

Ship Engineering Department, School of Transportation, Wuhan University of Technology, Heping Road, 430000 Wuhan,

Ship Engineering Department, School of Transportation, Wuhan University of Technology,

Path Following Control of the Underactuated USV Based On the Improved Line-of-Sight Guidance Algorithm

<abstract><title style='display:none'>ABSTRACT</title> Reliquefaction technologies are being currently applied on board liquefied natural gas (LNG) carriers on the basis of economic criteria and energy efficiency. A variety of reliquefaction techniques have been developed so far during the last decade. Nevertheless, technology enhancement continues being a research area of interest. In this article the different technologies applied to the reliquefaction of the boil-off gas (BOG) on LNG carriers have been described, analysed and discussed, contributing to highlight the process and operation characteristics as well as selection plant criteria. Finally, a comparison of the different reliquefaction plants, considering their capacities and efficiencies as well as other technical data of interest has been carried out.</abstract>

On board LNG reliquefaction technology: a comparative study

<abstract><title style='display:none'>Abstract</title>The accuracy of bathymetric maps, especially in the coastal zone, is very important from the point of view of safety of navigation and transport. Due to the continuous change in shape of the seabed, these maps are fast becoming outdated for precise navigation. Therefore, it is necessary to perform periodical bathymetric measurements to keep them updated on a current basis. At present, none of the institutions in Poland (maritime offices, Hydrographic Office of the Polish Navy) which are responsible for implementation of this type of measurements has at their disposal a hydrographic vessel capable of carrying out measurements for shallow waters (at depths below 1 m). This results in emergence of large areas for which no measurement data have been obtained and, consequently, the maps in the coastal zones are rather unreliable.The article presents the concept of bathymetric measurements for shallow waters with the use of an autonomous, unmanned survey vessel (ASV/USV). For this purpose, the authors modernized a typical ASV/USV unit with standard radio remote control system to the fully autonomous mode. As part of the modernization, the route planning software was created. The developed software works based on, alternatively, GNSS measurements of the coastline, or satellite images. The system was supplemented by an own autopilot (adapted for flying drones). Moreover, the method of controlling electric motors was changed thanks to the use of own electronic circuit.The modernized ASV/USV measuring system was verified by performing bathymetric measurements of the retention reservoir in Gdansk, Poland. Then, the obtained measurement data were used to create a digital bottom model and a bathymetric map of the reservoir.</abstract>

Application of an Autonomous/Unmanned Survey Vessel (ASV/USV) in Bathymetric Measurements

<abstract><title style='display:none'>Abstract</title> With the substantial rising of international oil price and global warming on the rise, how to reduce operational fuel consumption and decrease air pollution has become one of the pursued goals of green ship. Ship route planning is an indispensible part of the ship navigation process, especially in transoceanic crossing ship routing. The soundness of ship routing not only affects the safety of ship navigation but also the operation economy and environmental protection. This research is based on the platform of Electronic Chart Display and Information System (ECDIS), and founded on Ant Colony Algorithm (ACA) combined with the concept of Genetic Algorithm (GA), to model living organisms optimization behaviour to perform efficient ship route planning in transoceanic crossing. Besides the realization of route planning automation, ship routing will achieve the goal of optimum carbon dioxide reduction and energy conservation, and provide reference for route planning decision.</abstract>

National Kaohsiung Marine University, Kaohsiung, Taiwan, R.O.C.

Kaohsiung Marine University, Kaohsiung, Taiwan, R.O.C.

An Ant Colony Algorithm for efficient ship routing

<abstract><title style='display:none'>Abstract</title>In this paper are characterized problems of high strength steel weldability in underwater wet welding conditions. Water as a welding environment intensifies action of unfavourable factors which influence susceptibility to cold cracking of welded steel joints. The susceptibility to cold cracking of S355J2G3 steel and S500M steel in wet conditions was experimentally estimated (by using Tekken test). It was concluded that the steels in question are characterized by a high susceptibility to formation of cracks in welds. Usefulness of the proposed Temper Bead Welding technique (TBW) was experimentally verified as a method for improving weldability of the steels in the analyzed conditions.</abstract>

Weldability of high strength steels in wet welding conditions

Polish Maritime Research

The Journal of Gdansk University of Technology

 POLISH MARITIME RESEARCH is a scientific journal with a worldwide circulation. This journal is published quarterly (four times a year) by Gdansk University of Technology (GUT). On...

Impact Factor

Five Year Impact Factor

Cite Score

SNIP

MNiSW

Google Scholar h5-index

Google Scholar h5-median

 POLISH MARITIME RESEARCH is a scientific journal with a worldwide circulation. This journal is published quarterly (four times a year) by...

AHEAD OF PRINT

Volume 31 (2024): Issue 2 (June 2024)

Volume 31 (2024): Issue 1 (March 2024)

Volume 30 (2023): Issue 4 (December 2023)

Volume 30 (2023): Issue 3 (September 2023)

Volume 30 (2023): Issue 2 (June 2023)

Volume 30 (2023): Issue 1 (March 2023)

Volume 29 (2022): Issue 4 (December 2022)