Ship Size Research Articles

Examination of representative manifolds existence in passive sonar dataset

Conventionally, passive sonar classification has been conducted to predict a ship size for given sample. Recent studies have shown high accuracy, far exceeding the performance of early baselines. However, the assumption that manifolds of passive sonar dataset are formed according to the ship size hasn't been studied deeply. In this paper, we investigate the assumption and attempt to analyze the dataset to observe the manifolds. We consider various attributes of passive sonar signals including, which could form the manifold. We employ unsupervised and supervised learning methods with various extracted features. In our analysis, it is difficult to find an attributes dominantly forming the manifolds because passive signals significantly changed by various facts including ocean environment and moving status. Our study wil provide a deeper understanding of the dataset, leading to a realistic and robust passive sonar classifier.

A semi-analytical approach for dynamic responses of monopile-supported offshore wind turbines subjected to accidental loads

Offshore wind energy is leading the way in sustainable energy generation. Offshore wind turbines (OWTs) need to be designed to withstand extreme or accidental loads in Ultimate Limit States (ULS) and Accidental Limit States (ALS), whereby high order eigenmodes may become significant. This paper introduces a semi-analytical approach for efficient and reliable analysis of the dynamic responses of monopile-supported OWTs subjected to accidental loads. A Rayleigh-Ritz solution is initially adopted to determine the high-order natural frequencies and eigenmodes of monopile OWTs, explicitly considering tapered towers and soil-pile interactions. Dynamic responses of OWTs are then calculated depending on the interaction schemes between accidental loads and the structures, e.g. soft contact loads (e.g. slamming, wind) and hard contact loads (e.g. ship collisions, ice impact). For soft contact loading conditions, the loads are considered independent of turbine responses, and the transient dynamic response is computed using the classical modal superposition method. While for hard contact loading conditions, the load actions depend on the contact stiffnesses and responses of the interacting bodies. A numerical contact algorithm is thus developed, and numerical iterations are performed to ensure convergence. The proposed approach is applied to the DTU 10 MW monopile-supported OWT subjected to extreme water slamming and ship collisions, respectively as example applications of soft and hard contact scenarios. The results are verified against nonlinear finite element analysis using USFOS and discussed with respect to the turbine natural frequencies and eigenmodes, contact forces and dynamic responses. A parametric analysis is conducted for ship-OWT collisions, exploring different impact scenarios by varying ship sizes, contact stiffnesses, and initial impact velocities. The proposed approach can serve as a promising tool for accidental load response analysis and the design of monopile OWTs.

Numerical investigation on behaviour of mooring line system for container ship at berth

The constant growth of the world’s maritime industry has led to the need to increase the size of ships as wellas accelerate the trend of moving ports to open sea areas and outside estuaries. Increasing the size of ships,especially container ships, has the potential to cause unsafe ship anchoring in ports. Furthermore, the mooringof ships at the harbor also lacks international guidelines on the layout of the mooring system. Meanwhile, relocating seaports outside estuaries and open seas can create conditions for high winds, high tidal fluctuationsand strong currents to penetrate the port basin. This paper presents a study using the MIKE 21 MA numericalmodel to determine the most optimal mooring layout for a container ship as well as clarify the influence offactors (wind, current, water level and ship’s draft) on the tension force of the mooring lines. The most optimal mooring layout in the study scenarios was uncovered from the simulation results. In addition, wind wasidentified as the factor with the greatest influence on the tension force of the mooring system.

Multi-Domain Joint Synthetic Aperture Radar Ship Detection Method Integrating Complex Information with Deep Learning

With the flourishing development of deep learning, synthetic aperture radar (SAR) ship detection based on this method has been widely applied across various domains. However, most deep-learning-based detection methods currently only use the amplitude information from SAR images. In fact, phase information and time-frequency features can also play a role in ship detection. Additionally, the background noise and the small size of ships also pose challenges to detection. Finally, satellite-based detection requires the model to be lightweight and capable of real-time processing. To address these difficulties, we propose a multi-domain joint SAR ship detection method that integrates complex information with deep learning. Based on the imaging mechanism of line-by-line scanning, we can first confirm the presence of ships within echo returns in the eigen-subspace domain, which can reduce detection time. Benefiting from the complex information of single-look complex (SLC) SAR images, we transform the echo returns containing ships into the time-frequency domain. In the time-frequency domain, ships exhibit distinctive features that are different from noise, without the limitation of size, which is highly advantageous for detection. Therefore, we constructed a time-frequency SAR image dataset (TFSID) using the images in the time-frequency domain, and utilizing the advantages of this dataset, we combined space-to-depth convolution (SPDConv) and Inception depthwise convolution (InceptionDWConv) to propose Efficient SPD-InceptionDWConv (ESIDConv). Using this module as the core, we proposed a lightweight SAR ship detector (LSDet) based on YOLOv5n. The detector achieves a detection accuracy of 99.5 with only 0.3 M parameters and 1.2 G operations on the dataset. Extensive experiments on different datasets demonstrated the superiority and effectiveness of our proposed method.

Ship detection in reefs and deep-sea with medium-high resolution images

ABSTRACT Accurate and efficient ship detection is crucial for ocean monitoring and management, especially in reefs and deep-sea, where fishing and illegal activities threaten sustainability of ecosystems. Obtaining the size of ships in reefs and deep-sea helps to identify ship types and to assess the impact of ships on marine ecosystems quantitatively. Ship detections were mainly applied at coast or river of the inland region using high spatial resolution remote sensing data due to its rich details and frequent coverage. However, the ships located in reefs and deep-sea regions were rarely studied because of price, and availability of high spatial resolution remote sensing data. Global covered medium-high resolution (10–30 m) remote sensing data (such as Sentinel-2) makes it possible to obtain the spatial-temporal distribution of ships, especially small ships. This study developed a deep learning ship detection algorithm – an enhanced Rotated-Ship Detector (RShipDet) to detect ships in reefs and deep-sea regions. RShipDet was applied to Nansha Islands based on two medium-high resolution ship detection datasets (Sentinel2-Ship and SDGSAT-Ship). These two datasets include various backgrounds of reefs and deep-sea, and complex scenarios such as cloud cover and parallel ships, adapting RShipDet to ship detection under complex circumstances in reefs and deep-sea. The results showed that: (1) Small gains: gains of 3.3% and 8.7% Average-Precision (AP) compared to Rotation-equivariant Detector (ReDet) and Faster-RCNN on Sentinel2-Ship dataset; (2) Strong generalization capabilities: 77.4% AP on SDGSAT-Ship dataset; (3) Better performance under complex conditions: RShipDet obtained more accurate ship detection results over regions with cloud cover, islands and reefs, deep-sea, and ports compared to other classical detectors. Our algorithm could be applied for better management of ocean resources and activities in reefs and deep-sea.

The Constraints of Narrow Channels: Implications for Multimodal Logistics

Narrow passages, whether man made, place limitations, on the efficiency of multimodal logistics activities by affecting factors like ship size, cargo capacity, speed of transit and operational effectiveness. This paper delves into the impact of these constraints on logistics and supply chain management emphasizing the importance of developing approaches to overcome these obstacles. Key areas of study include how ships behave in waterways, scheduling and simulating traffic flow establishing passing protocols and reducing risks related to grounding incidents. The study also explores how technological advancements like ships and sophisticated navigation systems can improve safety and operational efficiency. Furthermore, it examines the benefits of integrating water routes into the broader supply chain network to enhance logistics performance and sustainability. Ultimately this research aims to offer insights for optimizing logistics operations in channels with a focus, on enhancing strategies and reducing transit times.

Ship Detection in Synthetic Aperture Radar Images Based on BiLevel Spatial Attention and Deep Poly Kernel Network

Synthetic aperture radar (SAR) is a technique widely used in the field of ship detection. However, due to the high ship density, fore-ground-background imbalance, and varying target sizes, achieving lightweight and high-precision multiscale ship object detection remains a significant challenge. In response to these challenges, this research presents YOLO-MSD, a multiscale SAR ship detection method. Firstly, we propose a Deep Poly Kernel Backbone Network (DPK-Net) that utilizes the Optimized Convolution (OC) Module to reduce data redundancy and the Poly Kernel (PK) Module to improve the feature extraction capability and scale adaptability. Secondly, we design a BiLevel Spatial Attention Module (BSAM), which consists of the BiLevel Routing Attention (BRA) and the Spatial Attention Module. The BRA is first utilized to capture global information. Then, the Spatial Attention Module is used to improve the network’s ability to localize the target and capture high-quality detailed information. Finally, we adopt a Powerful-IoU (P-IoU) loss function, which can adjust to the ship size adaptively, effectively guiding the anchor box to achieve faster and more accurate detection. Using HRSID and SSDD as experimental datasets, mAP of 90.2% and 98.8% are achieved, respectively, outperforming the baseline by 5.9% and 6.2% with a model size of 12.3 M. Furthermore, the network exhibits excellent performance across various ship scales.

Transoceanic pathogen transfer in the age of sail and steam

In the centuries following Christopher Columbus's 1492 voyage to the Americas, transoceanic travel opened unprecedented pathways in global pathogen circulation. Yet no biological transfer is a single, discrete event. We use mathematical modeling to quantify historical risk of shipborne pathogen introduction, exploring the respective contributions of journey time, ship size, population susceptibility, transmission intensity, density dependence, and pathogen biology. We contextualize our results using port arrivals data from San Francisco, 1850 to 1852, and from a selection of historically significant voyages, 1492 to 1918. We offer numerical estimates of introduction risk across historically realistic ranges of journey time and ship population size, and show that both steam travel and shipping regimes that involved frequent, large-scale movement of people substantially increased risk of transoceanic pathogen circulation.

Transportation system models to analyse ports competition and cooperation

Some global drivers of the shipping market, such as the carriers’ alliance consolidation process and the growing ship sizes have determined critical conditions in standalone ports in the XXI century. The traditional attitude of each port during the XX century was to consider other ports, even if they belong to the same territorial system, as competitors following the postulate of the natural monopoly of access to a territory. However, the necessity to respond to the binding requests of port users and of the ship gigantism brought to different experiences between ports belonging to the same territorial system. New forms of cooperation and competition took place at different levels. The paper presents a theoretical equilibrium model to analyse the competition and/or cooperation scenarios of two, or more, ports belonging to a territorial system. The model is based on the consolidated topological-behavioural paradigm of Transportation System Models (TSMs). The proposed equilibrium model allows to simulate the condition inside a port system, which moves from a competition attitude between ports to a cooperation one, within the same modelling framework. The model could provide to the port authorities, managers, planners and researchers a quantitative tool to understand the competition-cooperation scenarios and to define alternative strategies in relation to the decisions taken by other actors of the market.

제미나이 출범에 따른 글로벌 주요 항만의 영향 분석

Purpose : The purpose of this study is to analyze the representative differences between the services implemented by the launch of the Gemini alliance and the existing alliance services. Additionally, it forecasts the impact of the Gemini launch on Busan Port and other top 20 global ports. Research design, data and methodology : An empirical analysis is conducted using data from the Gemini alliance and the top 20 global ports. Specifically, the analysis derives the impact on ports by utilizing the representative differences of the Gemini service, such as the size of the ships and the frequency of regular service calls, including GDP. Results : All three independent variables (ship size, frequency of regular service calls, and GDP) were found to have a significant impact on port throughput. In particular, the size of the ships and the frequency of regular service calls have a relatively greater impact compared to GDP. Conclusions : The frequency of regular service calls by Gemini at Busan Port is expected to decrease significantly, raising concerns about a potential reduction in Busan Port's throughput. However, considering the increase in the size of feeder ships and Gemini's market share of 20%, it is deemed unlikely that Busan Port's throughput will immediately decrease significantly due to the Gemini launch. Therefore, the success of the differentiated services promoted by Gemini is crucial.

Determination of Ship Length and Draft on the Planning Stage of Cruise Ports in Turkiye

The evolution of cruise tourism, despite facing unprecedented challenges from the Covid-19 pandemic, has shown resilience, with a rapid recovery observed in 2022. This manuscript emphasizes the significance of analyzing cruise ship length and draft data for Turkish ports to facilitate effective development planning. Despite data availability challenges, percentiles of ship lengths and drafts have been established, offering insights into port capacity and future infrastructure requirements. The examination of ship length and draft requirements highlights the diverse needs of ports from Alanya to Trabzon. Continuous monitoring and adjustment of development plans are essential to adapt to evolving industry trends, such as the increasing size of cruise ships. Projections indicate a consistent upward trend in ship sizes, emphasizing the need for forward-looking investment strategies. This study provides a foundation for informed decision-making in port development, offering insights to optimize port efficiency and competitiveness. By assessing regional effects and proposing pragmatic investment approaches, the manuscript serves as a valuable resource for guiding future infrastructure investments in Turkey's maritime industry, ensuring its sustainable growth and competitiveness.

Ultimate strength of welded aluminium stiffened panels under combined biaxial and lateral loads: A numerical investigation

The number and size of aluminium non-monohull ships have been steadily increasing over time. This raises growing concerns regarding their structural strength, especially considering the adverse effects of the heat-affected-zone (HAZ) on welding connections in aluminium structures. This paper investigates the ultimate strength of welded aluminium stiffened panels under combined biaxial compressive loads and lateral pressure through the application of numerical simulations. Altogether 360 cases are simulated with varied panel lengths, welding patterns and load combinations. The results are presented and discussed with respect to force end-shortening curves, failure modes and ultimate strength. Influences of the combined loads and HAZ effects are summarized. The numerical results are compared to two commonly used design methods in the marine industry, the International Association of Classification Societies (IACS) rule and the Panel Ultimate Limit States (PULS) approach. Their applicability to welded aluminium stiffened panels is discussed, and modifications are suggested with respect to the transverse loads, lateral pressure, and HAZ effects.

Four-DOF Maneuvering Motion of a Container Ship in Shallow Water Based on CFD Approach

With the continuous increase in ship size combined with the generally slower increase in the sizes of waterways, the need for the prediction of ship maneuvering in shallow waterways continues to attract attention from the international scientific community. Ship behavior in shallow water is relevant in seabed effects that result in changing the hydrodynamic forces acting on a ship. In this study, the maneuvering characteristics of a container ship with four degrees of freedom in shallow water are analyzed. The Reynolds-Averaged Navier Stokes approach in Ansys Fluent code is used to produce the maneuvering coefficients through the simulations of forward running, static drift, static heel, circular motion, the combined motions, and the pure roll motion of the KRISO container ship. The maneuvering characteristics of the ship are estimated for evaluating the ship behaviors in shallow-water conditions. The obtained results show that the roll has a significant decrease and the ship’s turning diameter has a significant increase when the ship operates in a shallow waterway. The predictions of the maneuvering characteristics of the ship are in good agreement with those of free-running model tests, indicating that the numerical simulation based on the Computational Fluid Dynamics method has compromising capability to predict the maneuvering derivatives and the four-DOF ship maneuvering motion in shallow water as well.

Concept Design of Typhoon Power Generation Ship Using System Simulation

A concept of a typhoon power generation ship for utilizing enormous typhoon energy is proposed. This paper developed a system simulator for evaluating and designing the concept of a typhoon power generation ship using typhoon track history. A developed simulator was applied to the case study to design a typhoon power generation ship ship that operated near Japan. The case study showed that the annual power generation of the typhoon power generation ship tends to saturate and become constant earlier when the number of typhoons is small, in contrast to the improvement of power storage capacity. This result indicates that the appropriate size of the typhoon power generation ship exists at the current technology level.

An Improved Artificial Potential Field Method for Ship Path Planning Based on Artificial Potential Field—Mined Customary Navigation Routes

In recent years, the artificial potential field has garnered significant attention in ship route planning and traffic flow simulation. However, the traditional artificial potential field method faces challenges in accurately simulating a ship’s customary route and navigating experience, leading to significant deviations in prediction results. To address these issues, in this study, we propose an innovative method for simulating and predicting ship traffic flow, building upon the artificial potential field approach. We introduce an AIS track heat map based on the kernel density function and enhance the artificial potential field model by incorporating factors, such as ship navigation habits and ship size. Through a comparison of traffic flow changes before and after the construction of a wind farm, the optimized model demonstrates its effectiveness in improving the accuracy of prediction results.

Exploring the ship operation safety indicators of international ports in Taiwan

Port safety plays an important role in port operations. Ship size has become larger and the port environment has rapidly changed in recent years. Ship accidents occur in the port area due to the complex environment in the port area. To improve past decision analysis methods on port operation safety fields and reduce fatalities and financial loss for potential accidents, the novelty of this study is to construct a safety index of ports with the application of the Best Worst Method (BWM). Four dimensions and 14 indicators were summarized based on an intensive literature review. The BWM was implemented to prioritize the weights of dimensions and indicators. Based on 21 expert questionnaires, the results indicate that the ranking of dimensions is ‘human’, ‘ship facilities’, ‘port facilities’, and ‘documentation check’. Regarding the ranking of indicators, the top three are ‘fire-fighting and life-saving equipment’, ‘captain’, and ‘pilot’. Safety improvement strategies (e.g. revising inappropriate operational rules and strengthening human safety education and training) based on these research findings are provided. The merits of this paper are presenting a simpler questionnaire-filling method and overcoming the traditional complicated questionnaire survey process and research limitations (e.g. indicator independence problems in the Analytic Hierarchy Process, and the complexation of filling out a questionnaire in the Analytic Network Process). In addition, the findings can help decision-making for port management authorities, port practitioners, and shipping operators (shipowners) regarding policy implementations of port safety.

The Coastal Landscape of West Samos in the Seventh and Sixth Centuries BCE: Possible landing points and routes

This article uses a combination of archaeological, environmental and historical evidence to consider where the most plausible shipping routes and landing points were around the west part of the Aegean island of Samos during the period 700–500 BCE, a time known for significant maritime activity in the region. Emerging evidence suggests that the west part of Samos, although subject year-round to strong and dangerous winds and lacking in safe anchorages along its coastline, connected itself in antiquity to a range of regional and supra-regional maritime networks. This article provides an important discussion for considering the practicalities of how those networks operated. Taking into account the size and capacity of ships sailing the Aegean in the seventh and sixth centuries BCE, this article considers how small ships would have fared in this region, in light of annual wind forecast, coastal topography and offshore bathymetry. Although there is a dearth of primary historical evidence from this period, comparative written accounts from the early modern period provide an opportunity for reflecting on how this area of the Aegean could have been navigated in small craft. This article closes by presenting a synthesis of possible year-round and seasonal routes usable around the island.

Dominant conditions for strong resonance of an advancing containership under small-amplitude regular waves

ABSTRACT Seakeeping of a ship under waves is vital for safety, with strong resonance occurring when two conditions are met: (1) large wave loads, and (2) wave frequency being close to the natural frequency. Prior research focused on resonant phenomena, nonlinear traits, and failure modes, but the dominant condition for resonance in ocean-going ships is unclear. This study developed a mathematical model using the boundary element method (BEM) for an advancing ship under small-amplitude waves. An open-source solution was proposed, utilizing NEMOH for hydrodynamic coefficients and a Python code for dynamic equation solving. Validated with KRISO Container Ship (KCS) data, the mathematical model accurately predicts ship motions. Findings show that ship heave resonance is influenced by both conditions, but the second condition affects rolling more, and the first condition controls pitch more. This is more evident in high-speed ships and is less affected by ship size variations.

The impact of container call size - evidence from simulation modelling

We present an analysis of the impact of large container ship call sizes on the operational efficiency of container terminals as well as on hinterland modes of transport. We use standard container terminal simulation software, that can represent a realistic terminal operation. We include dynamic crane productivity, arrival time uncertainty, and deepsea vessel prioritisation in our model.Our experiments investigate the impact of introducing larger call sizes of container ships, increasing the uncertainty in arrival times of deepsea ships, and the impact of the phenomenon of split calls that are employed by the largest container ships in certain regions in the world. We differentiate between the impact on terminal operations, land-based hinterland traffic, and hinterland traffic over water, through barges and feeder vessels.Our results show that introducing large ships with large container call sizes comes with benefits and drawbacks. Benefits can be found in planning advantages for both the deepsea ships and barges and feeders handled in the terminal. Drawbacks occur as a result of operational peaks in subsystems such as the quay cranes, the stack and the land side gates. Higher uncertainty deteriorates the performance of the terminal, but the impact on the hinterland modes of transport is greater than on the large deepsea vessels. The impact of the split call is that it brings all the disadvantages of large vessels, but none of the benefits.Our analysis shows the operational impact of large call sizes on terminal operations and hinterland transport operations, based on container terminal simulations with a higher degree of realism than previous work. In addition, we offer, for the first time, insights in the impact of split calls of container ships at container terminals.

The New Requirements for International Seafarers' Comprehensive Quality due to the Large-scale and Intelligent Development of Ships

The global shipping industry is undergoing significant transformations with the large-scale and intelligent evolution of ships, which poses new demands on the skills and responsibilities of seafarers. This article explores how these trends affect the skill requirements of seafarers, including mastery of advanced technology, data analysis capabilities, safety management, emergency response, and communication and collaboration. As ship sizes increase and intelligent technologies are widely applied, the ways of navigational operations and management are undergoing revolutionary changes. Seafarers must enhance their skills to adapt to the new work environment and meet the rapid changes in the shipping industry. This article aims to provide guidance for seafarer training and education, helping them successfully face these new challenges.