E-ISSN: 2148-9386
Journal of ETA Maritime Science - JEMS Maritime Sci: 12 (1)
Volume: 12  Issue: 1 - 2024
1.Full Issue

Page I

Selçuk Nas
doi: 10.4274/jems.2024.21548  Page 1
Abstract |Full Text PDF

3.Optimization of Countermeasures to Stable and Protect Navigation Channels in Dinh An Estuary and Coastal of Tra Vinh Province, Vietnam
Viet Thanh Nguyen, Anh Dan Nguyen, Vinh An Le
doi: 10.4274/jems.2023.70446  Pages 2 - 13
The new navigation channel for large vessels entering the Hau River through the Kenh Tat and Quan Chanh Bo channels was announced in January 2016. The navigation channel route through Dinh An estuary in Soc Trang province to Can Tho port was not deeply concerned by the agency because of the sedimentation phenomenon, which was very serious and complicated. Only small vessels of 1,000-2,000 DWT can pass through the Dinh An estuary navigation channel, whereas large vessels pass through the Kenh Tat and Quan Chanh Bo channels. However, the new navigation channel entering the Hau River is also seriously sedimented, especially in the Cua Dai An area, where the tributary route starts from the Hau River through the Quan Chanh Bo channel and the estuary area in the Duyen Hai harbor basin. These are two important bottlenecks that drastically reduce the throughput capacity of this new navigation channel. This paper proposed five options for the spatial arrangement of works to stabilize and protect the channel through the Dinh An estuary. A MIKE 21 couple mode was used to simulate hydrodynamic and sediment transport in the study area, and the impact of these options on the characteristics, including water level, flow velocity, and bottom topographic change, was analyzed and evaluated. Based on these results, an optimal solution was suggested.

4.Investigation of Scale Effects on Linear Vertical Maneuvering Derivatives of a Submarine
Emre Kahramanoğlu, Savaş Sezen, Ferdi Çakıcı
doi: 10.4274/jems.2023.72325  Pages 14 - 24
This paper aims to show the scale effects of vertical maneuvering derivatives for an underwater vehicle using computational fluid dynamics (CFD). The model scale and full-scale benchmark DARPA suboff hull forms were used in numerical vertical planar motion mechanism simulations to achieve this aim. The heave forces, pitch moments, and Euler coefficients are calculated together with the linear vertical maneuvering derivatives by implementing the Fourier series expansion approach. The results show that the coupled added mass terms are significantly influenced by the scale effects, whereas the impact of scale effects on the decoupled added mass and coupled and decoupled damping terms is negligible. Considering that the effects of the coupled added mass on the vertical maneuvering characteristics are almost negligible, the vertical maneuvering of a submarine is slightly influenced by the scale effects.

5.Hierarchical Management System for Container Vessels Automated Cargo Handling
Luidmyla Leonidovna Nikolaieva, Taras Yurievitch Omelchenko, Oleksandr Viktorovich Haichenia
doi: 10.4274/jems.2023.32858  Pages 25 - 35
Hierarchical management system is the next step for the development of container terminals all over the planet. The existing restrictions in transshipment operations are difficult to predict and invariably lead to a decrease in the terminal's throughput. The authors show that in modern control systems for the operation of a port container terminal, most of the automated processes use imperfect work algorithms and require optimal control based on the development of new approaches. The hierarchical multi-level control system proposed in the work, in comparison with traditional control methods, allows to reach the level of minimum energy consumption with the highest possible speed of containers unloading from the ship. For this control system, the authors formulated a model, an algorithm for implementing the work of control controllers and set optimal levels of control over work processes.

6.Competitiveness Factors of a Shipyard in the Era of New Uses of Oceans
Brais Preto-Fernández, Natalia Paleo-Mosquera, Almudena Filgueira-Vizoso, Ramon Yáñez-Brage, Laura Castro-Santos
doi: 10.4274/jems.2023.91249  Pages 36 - 49
The aim of this paper is to examine the most relevant competitive factors of a shipyard. The method conducted interviews and questionnaires with multiple agents related to the company and analyzed several institutional, business, and academic documents. The case of study considered was the manufacturing center of Navantia, S.A. in the Ferrol estuary (A Coruña, North-West of Spain). The results indicate that the five most important competitive factors are the government and political support, the production organization, the product technology, manpower, and skills and knowledge. Thus, these five competitive factors are critical to analyze the competitiveness of a shipyard with the characteristics of the one studied for new uses of the ocean, such as offshore wind, wave energy, or aquaculture.

7.A Threat to Maritime Trade: Analysis of Piracy Attacks Between 2015 and 2022 and the Period of COVID-19
Nur Jale Ece
doi: 10.4274/jems.2023.00377  Pages 50 - 63
More than 80 percent of world trade is transported by sea. Maritime piracy negatively affects international maritime transport and trade. The aim of the study is to analyze maritime piracy attacks between 2015-2022 and during the coronavirus disease-2019 (COVID-19) period. In the study, a literature review, main reasons and statistics for piracy and armed robbery attacks, international efforts to combat maritime piracy were examined and maritime piracy attacks were analyzed in 2015-2022 and the COVID-19 period. The results of the main findings are as follows; the most piracy attacks occurred in 2015, the most attacks were occurred in March-April-May majority of attacks occurred between the hours 24: 00-04: 00, the most attacks occurred in South East Asia, the most types of attacks against to ships was boarded. Marshall Islands-flagged ships were the most attacked. There is a weak statistical relationship between the piracy attacks by months and regions and between the piracy attacks by years and type of attacks. There is no statistical relationship between other variables.

8.Modelling Using Neural Networks and Dynamic Position Control for Unmanned Underwater Vehicles
Melek Ertogan, Philip A. Wilson
doi: 10.4274/jems.2024.46514  Pages 64 - 73
Underwater construction, maintenance, and mapping use autonomous underwater vehicles (AUVs) for path planning, path following, and target tracking operations. However, dynamic position management and localization of AUVs are critical issues. Correct localization and dynamic position management to prevent drifts can be used to acquire information on energy efficiency, another crucial topic. In this paper, AUV dynamic modeling using experimental data and position control is studied. The experiments were implemented on a Delphin2 scaled AUV model belonging to the Engineering and Environment Faculty, University of Southampton, UK. Hover and flight style motions according to the different speeds of Delphin2 were implemented in the test tank. Nonlinear coupled mathematical models were studied using shallow neural networks. The models are formed into depth-pitch and heading motion black-box models using the shallow neural network (SNN) algorithm. Proportional integral derivative control of heading motions and depth-pitch motion simulation studies were applied to the SNN model.

9.Analysis of the Structure of Marine Propeller Blades for Ice Navigation
Aydın Bozkurt, Melek Ertogan
doi: 10.4274/jems.2024.97769  Pages 74 - 82
This study’s analysis of the maritime propeller blade structure in ice navigation was motivated by an incident that caused the tip of a propeller blade to bend. The aim of this study was to demonstrate how the ice layer’s confined space effect causes propeller blade tips to bend. Using computer-based software, a three-dimensional model of the propeller was created. The geometry of the three-dimensional propeller model was imported using the finite element approach into another piece of software. The propeller model and the environment were constructed after designing the ice environment. Using the computational fluid dynamics method, flux was calculated, and the composed pressure was derived. Following the specification of the alloy material for the propeller, the static structural module applied pressure values acquired to the propeller to measure the total deformation and stress. The data comparing the results of the simulation study are based on full-scale measurements. The maximum deformation in Ansys was 2.7-3.5 cm, whereas in the incident, it was 12 cm, which can be explained by persistent pressure or repeated initial movement steps. Considering these findings, the reason for blade tip bend, preventive measures, and recommendations have been proposed.

10.Model Validation and Hydrodynamic Performance of an Oscillating Buoy Wave Energy Converter
Giri Ram, Mohd Rashdan Saad, Noh Zainal Abidin, Mohd Rosdzimin Abdul Rahman
doi: 10.4274/jems.2024.05025  Pages 83 - 91
An oscillating buoy (OB) could function simultaneously as a wave energy converter and a breakwater. In this work, a numerical study is conducted to assess the ability of the buoy to perform both aforementioned tasks by quantitatively and qualitatively assessing its hydrodynamic performance. The computational fluid dynamics solver used for the numerical study is ANSYS Fluent, which uses Reynolds-averaged Navier-Stokes equations and Volume of Fluid method for the design and simulation of the numerical model, which consists of a rectangular OB that floats on the surface of a numerical wave tank. First, a total of six independent studies, namely the time, meshing, damping, overset geometry, flow viscosity, and spatial studies, were conducted for validation purposes. Second, calculation and analysis of the heave and transmission coefficients and vorticity magnitude were conducted to assess the hydrodynamic performance. Results of independent studies show cases with a high degree of accuracy to the experimental model, whereas results for hydrodynamic performance show a generally increasing heave movement of OB and transmission coefficient across the range of wave periods studied. Meanwhile, the vorticity magnitude flow fields show at least two vortices for all wave periods studied, except for the shortest two wave periods.

11.A TAM-Based Study on the Adoption of Digital Transformation in the Maritime Transportation Logistics Sector
Orçun Gündoğan, Tuba Keçeci
doi: 10.4274/jems.2024.26680  Pages 92 - 105
Digital transformation is a significant global trend of the 21st-century that has substantial ramifications for various companies and sectors. It is inconceivable to envision that the maritime transport logistics industry will remain unaffected by these advancements. Digital transformation has the capacity to fundamentally revolutionize the business processes, services, and strategies of organizations working within this industry. This study examines the process of digital transformation within the maritime sector and identifies the key factors that influence its adoption. The research used structural equation modeling methodology to examine the variables and specific components indicated in the technology acceptance model. The data used in the analysis were collected via a questionnaire administered to individuals engaged in the maritime transport industry. The findings of the study indicate that the degree to which employees in the industry embraced digital transformation technologies was influenced by various factors, including their perception of how easy these technologies were to use and the perceived benefits they offered. The study’s findings offer strategic suggestions for improving the successful implementation of digital transformation in the maritime logistics sector.

12.LNG Shipping as a Diversification Tool for Energy Security: The Impact of the Ukraine-Russia War on LNG Ship Orders
Abdullah Açık
doi: 10.4274/jems.2024.43926  Pages 106 - 114
Natural gas is one of the most important energy sources used in many fields since ancient times. Because it is monopolized by some countries due to its random distribution throughout the world, it can be difficult to supply this energy source in times of crisis with its suppliers. The most recent example of this is the war between Russia and Ukraine. Especially since European countries are mostly dependent on Russia and have problems in gas supply, they have turned to LNG transportation for resource diversification and increased demand. On the other hand, increasing demand caused a backlog in LNG ship orders. In this study, we aimed to determine whether there is a structural break in the order amounts of LNG ships, especially due to the recent war. As a result of the structural break analysis applied to monthly data, it was determined that an increase in orders started months before the war and that the highest orders of all time were placed during the war period. This situation can be explained by the fact that European countries accelerate their LNG infrastructure investments in order not to experience the problems brought by high dependency again, and this situation increases the high demand expectations in the sector and increases ship orders. Thus, the LNG market will continue to be an important sector in ensuring energy supply security in the near future.

13.Reviewer List of Volume 12 Issue 1 (2024)

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