Physical model tests are often conducted during the design process of coastal structures. The wave climate in such tests often includes short-crested nonlinear waves. The structural response is related to the incident waves measured in front of the structure. Existing methods for separation of incident and reflected short-crested waves are based on linear wave theory. For analysis of nonlinear waves, the existing methods are limited to separation of nonlinear long-crested waves. For short-crested waves, the only options so far have been to use estimates without the structure in place. The present paper thus presents a novel method for directional analysis of nonlinear short-crested waves: Non-Linear Single-summation Oblique Reflection Separation (NL-SORS). The method is validated on numerical model data, as for such data, the target is well defined as simulations may be performed with fully absorbing boundaries. Second- and third-order wave theory is used to demonstrate that small errors on the celerity of nonlinear components in the mathematical model of the surface elevation can be obtained if a double narrow-banded directional spectrum is assumed, ie the primary frequency and the directional spreading function must be narrow banded. As the increasing nonlinearity of the waves often arise from waves shoaling on a sloping foreshore, the directional spreading of the waves will decrease due to refraction, and a broad directional spreading function will thus not be experienced in highly nonlinear conditions. The new NL-SORS method is shown to successfully decompose nonlinear short-crested wave fields and estimate the directional spectrum thereof.
We consider the Tramp Ship Routing and Scheduling Problem (TSRSP) in which we plan routes for a fleet of tramp shipping vessels operating on a combined contract and spot market. Earlier research has been fragmented due to variations in the side constraints studied. Hence we present the first unified model that can handle speed optimization, chartering costs, bunker planning, and hull cleaning. The model is solved by column generation, where the columns represent the possible routes of a vessel, while the master problem keeps track of the binding constraints. The pricing problem is solved efficiently using a time–space graph and several dominance rules. Real-life instances with up to 40 vessels, 35 geographic regions, and four months planning horizon can be solved to optimality in less than half an hour. The optimized routes increase earnings by 7% compared to historical schedules. Furthermore, policy-makers can use the model as a simulation of a rational agent behavior.
Current practice for maritime search and rescue (MSAR) adheres to predetermined full-coverage patterns for finding targets. These do not account for key success factors for MSAR missions such as the dynamic location of targets, updates on situational awareness during mission execution, and search vehicle kinematics. Consequently, current practice cannot incorporate realistic MSAR operational conditions into path-finding, increasing the likelihood of mission failure. To address this issue, a novel, flexible path-finding framework is proposed for generating a path while dynamically updating the probability of a target based on the path's trajectories. The solution approach implements the A* algorithm, which can accommodate the dynamics of a vehicle and guarantees the optimality of the final path with respect to the target objective function. Experiments show that a more than 50% improvement in the time needed to guarantee a certain probability of finding a target is exhibited compared to the parallel sweep coverage path-finding approach.
Background: Medical evacuations (MEDEVACs) from offshore installations are both costly and disruptive. Enhancing worker well-being may help reduce evacuations due to illness or injury, thereby maintaining the smooth operation of offshore activities and lowering financial burdens.
Objectives: This scoping review aims to identify whether illness or injury is the predominant cause of MEDEVACs from offshore oil and gas installations and to determine the most common types of illnesses or injuries involved. Additionally, the review outlines a future research agenda focusing on offshore worker health and well-being.
Materials and methods: A comprehensive structured search was conducted across the Scopus, PubMed, and Web of Science databases, as well as through reference lists and grey
literature. Studies were included if they addressed MEDEVACs from offshore oil and gas installations. Eleven articles met the inclusion criteria.
Results: Articles indicate that non-occupational illnesses are more frequent causes of MEDEVACs than injuries. Among these, chest pain, cardiovascular issues, and dental problems were disproportionately represented. Contractor personnel were more likely to require evacuation than company employees. Additionally, younger workers were more likely to be evacuated due to injuries. Chronic health conditions were more common reasons for MEDEVACs among older workers. The review highlights the significant role of non-communicable diseases in contributing to MEDEVACs, as opposed to occupational exposures.
Conclusions: Investing in preventive health management, targeted research, and workforce education may substantially reduce the prevalence of non-communicable diseases in the offshore environment, lowering MEDEVAC rates, associated costs, and operational disruptions. Further investigation into the underlying causes of ill health among offshore workers is needed to enhance overall workforce well-being.
Background
The transfer of offshore wind farm workers between transport vessels and wind turbines is a hazardous operation with a disproportionately high occurrence of "high potential" incidents. Motion sickness has been reported to affect offshore wind farm worker well-being, and has been identified as a job demand, especially during crew transfer and ladder-climbing operations.
This scoping review sought to determine the extent to which current research defines, describes, and quantifies MS among offshore wind farm workers and to identify relevant research gaps.
Methods
Using terms related to motion sickness and offshore wind farm operations, searches were conducted of the PubMed, Scopus, and Web of Science databases. Studies published in English between 1990 and 2024 were included.
Results
795 articles were retrieved, of which 11 articles met the inclusion criteria. The included articles describe MS as a job demand but do not clearly define it in the research context. Consequently, it remains unclear which symptoms of MS constitute a job demand and how workers are affected. Additionally, indications of motion sickness prevalence are required, using a clear definition which accounts for the wide range of subjective symptoms other than vomiting.
No research appears to have been carried out where motion sickness among wind farm workers has been studied as a broad occupational health issue within the offshore wind energy sector.
Conclusions
This review identifies significant research gaps concerning motion sickness among offshore wind farm workers. Motion sickness-related issues have either been overlooked, studied in isolation, or insufficiently addressed. These issues constitute empirical, methodological, and knowledge gaps, necessitating a need for systematic studies that address these research gaps in the context of the offshore wind energy sector.
OBJECTIVES: Cardiovascular disease (CVD) is the leading cause of death globally and the second most frequent cause of death in Denmark. Due to their unique occupational environment, seafarers are exposed to numerous risk factors for CVD including lifestyle and work-related factors. This study aims to investigate CVD mortality among Danish seafarers by comparing them to the economically active reference population.
METHODS: This register-based cohort study included data on all Danish seafarers from 1993 to 2016 and compared them with the economically active Danish population not working as seafarers. The seafarers' mortality was calculated using piecewise stratified Cox regression adjusting for potential confounders. Mortality was further analyzed by diagnosis groups, vessel type and employment duration.
RESULTS: Among 52 861 seafarers, 4226 deaths were observed, with 866 (20.5%) of these attributed to CVD. Male seafarers had higher all-cause mortality in age groups 18-44 years (HR 1.46, 95% CI 1.33 to 1.62), 45-64 years (HR 1.43, 95% CI 1.37 to 1.50) and 65+ years (HR 1.32, 95% CI 1.26 to 1.39) compared with the reference population. CVD mortality was increased for male seafarers aged 45-64 years (HR 1.27, 95% CI 1.13 to 1.42) and 65+ years (HR 1.34, 95% CI 1.21 to 1.48). The mortality was higher for male seafarers for ischemic heart diseases, other forms of heart diseases, cerebrovascular diseases and diseases of arteries, arterioles and capillaries. CVD mortality was also observed based on vessel type.
CONCLUSIONS: The study provides evidence of elevated CVD mortality among Danish seafarers. Future research should focus on identifying effective strategies to improve the cardiovascular health of seafarers.
The core function of UNCLOS is to provide a legal order for the oceans and their peaceful uses. This includes providing a legal framework for upholding law and order at sea, as this is a precondition for peaceful use. Part One of this volume deals with different perspectives of upholding law and order at sea; and Chapter 2 creates a backdrop for the following chapters dealing with these various issues. The chapter presents some perspectives on the system of law and order at sea and sets the following chapters in context with themes such as the scope of UNCLOS and its limitations, the adaptability of the convention to new developments, the role of the zonal system created under the convention and the influence of state practice on the system of upholding law and order at sea. By doing so, Chapter 2 also creates a line to the following parts of this volume; and some of the perspectives raised in Chapter 2 will be revisited in the final part (Part Four) of this volume, dealing with UNCLOS as a system of regulation and connected methodologies.
We present computations of cavitating flow over a NACA0015 hydrofoil. The simulations are performed by a finite volume compressible Euler model with dynamic mesh adaptation. The adaptive mesh refinement (AMR) is driven by a generic, simple and efficient error estimator based on the jump in value between cell faces for a given variable. It is shown that AMR based on vapour fraction provide unsatisfactory results both for (quasi-) steady and unsteady cavitation, as the major flow features are not captured. Instead, adaptivity driven by the Q-value proved successful even for resolving the cavity interface.
As ocean space increasingly is used for production purposes, such as for the production of food and feed, renewable energy and resource mining, competition for space becomes a concern. A spatial solution to this is to co-locate activities in a multi-use setting. Next to the direct (financial) costs and benefits of multi-use and the societal cost and benefits, there are other factors, in the realm of legal aspects, insurance, health and safety issues and the overall governance of multi-use, that determine whether multi-use can be implemented successfully. This includes transaction costs that arise when for example non-adequate regulation, governance and insurance schemes are in place. Based on the analysis of five case studies across Europe these combined/collective transaction costs of multi-use are analysed and suggestions how to reduce and/or overcome these transaction costs are presented.
This study examines how the work of the International Law Commission (ILC) has contributed to the ‘progressive development’ of general international law relevant to regulating rescue and disembarkation of refugees and migrants found at sea. It explores the ILC’s texts on interpretation and implementation of international obligations, state responsibility, fragmentation and harmonization of international law, and the status of certain principles of general international law, including jus cogens general principles of law and the principle of good faith, which present legal parameters for regulation of maritime search and rescue operations. In conducting doctrinal examinations of international law and gathering evidence of the practice of States and other relevant actors, the ILC contributes by analysing, clarifying, and systemising important topics of general international law. However, state implementation frequently falls short of the legal interpretations of the ILC, particularly as they relate to respect for and protection of human rights at sea. Therefore, while the ILC needs new strategies to directly connect with States and international organisations, it remains reliant on the mutual following of national and international courts and tribunals, and its mutual contribution in scholarship.