In hydraulic model tests, it is common practice to relate the response of the tested structure to the incident wave parameters at the toe. Estimation of the incident wave parameters at the toe is thus an essential part of the analysis of hydraulic model testing. In many cases, the design conditions at the toe are given by waves that are highly nonlinear or even depth limited. Modelling such conditions requires reproducing the prototype foreshore slope in the model. The present paper provide guidelines on the accuracy of a nonlinear reflection separation algorithm when applied to nonlinear waves over sloping foreshores. A simple methodology has been established to estimate the expected errors on the incident wave parameters.
Simulating the free decay motion and wave radiation from a heaving semi-submerged sphere poses significant computational challenges due to its three-dimensional complexity. By leveraging axisymmetry, we reduce the problem to a two-dimensional simulation, significantly decreasing computational demands while maintaining accuracy. In this paper, we exploit axisymmetry to perform a large ensemble of Computational Fluid Dynamics (CFDs) simulations, aiming to evaluate and maximize both accuracy and efficiency, using the Reynolds Averaged Navier–Stokes (RANS) solver interFOAM, in the opensource finite volume CFD software OpenFOAM. Validated against highly accurate experimental data, extensive parametric studies are conducted, previously limited by computational constraints, which facilitate the refinement of simulation setups. More than 50 iterations of the same heaving sphere simulation are performed, informing efficient trade-offs between computational cost and accuracy across various simulation parameters and mesh configurations. Ultimately, by employing axisymmetry, this research contributes to the development of more accurate and efficient numerical modeling in ocean engineering.
Background: Seafarers are at an increased risk of developing cardiovascular diseases (CVDs), potentially due to a stressful working environment and behavioral risk factors. To develop better prevention strategies, it is important to elucidate the extent of this risk. Therefore, we conducted a systematic literature review on CVD in seafarers. Method: We conducted systematic searches in five databases. All studies investigating CVDs among occupational seafarers, published in articles or conference papers, were eligible for inclusion. The identified records were screened and reviewed by two independent researchers, who also evaluated the methodological quality of the included studies. Results: Three thousand nine hundred and seventeen records qualified for screening, and 55 were eligible for inclusion. Most of the studies were observational, including cohort, frequency, incidence or prevalence studies, and review of case records. Around half were assessed at risk of biased findings. Participants in the studies were primarily from North America or the European continent and work onboard transportation vessels. Many studies investigated CVDs as a cause of death, focusing on conditions such as CVD, ischemic heart disease, and myocardial infarction. Frequency of CVD conditions varied but indicate that seafarers face a greater risk compared to the reference populations or control groups. Environmental factors were mainly investigated as risk factors. Conclusion: Our results indicate a higher risk of CVDs among seafarers compared to reference or control groups. However, due to the variable quality of the evidence, well-designed studies are needed to establish the causes of cardiovascular mortality and morbidity in seafarers and to investigate behavioral aspects of cardiovascular risk.
Harbour vessel emissions are growing concerns in the maritime industry regarding environmental sustainability. Accurate emissions prediction can stand in monitoring and addressing the issue. This study proposes a machine-learning approach using Artificial Neural Network (ANN) for predicting harbour vessel emissions. The approach shows superiority over the bottom-up method introduced by the 4th IMO GHG Study regarding prediction accuracy. Actual emissions data from onboard measurements are used for training ANN models and as references for evaluating the methods. Compared to the bottom-up method, the improvement in error reduction can be up to 30% for predicting nitrogen oxides and 54% for carbon monoxide when only using ship-related factors as input variables. By adding selected meteorological factors in the experiments, the prediction accuracy enhancement can achieve up to 48% for nitrogen oxides and 62% for carbon monoxide. The proposed ANN approach could assist relevant stakeholders in improving emissions prediction and operations optimisation.
Why should we look to the past to understand privacy and the ways we can protect it? Privacy, as a contemporary concept, already seems to be challenging to define and regulate enough. With the ever-speeding technological developments we face today, it is hard to catch up with all the different ways in which our privacy can be breached. In the case of the maritime context, the complexity increases. Issues of jurisdiction, as well as the maritime control of the mobility of goods, information, and people, make tackling ‘privacy at sea’ a difficult task. Regulating forces, such as the European Maritime Safety Agency, need to be clear on their security measures, which must include a balance between surveillance for safety and personal data protection on the one hand and general privacy for people in vessels on the other.1 Looking back to history could, therefore, appear counterproductive, adding intricacies to an already convoluted issue. However, shifting perspectives to understand the historical roots of how such issues developed and to pay heed to what people continuously try to protect when advocating for privacy helps us break those dichotomies that make the balance between public safety and privacy harder to reach.
The agenda of objectual International Relations has shown why object matters, how they arise and with what effects. Far less attention has been paid to how objects are maintained and stabilized over time and how their coherence is achieved. To add this dimension to the debate, we suggest turning to the infrastructures of object maintenance. Infrastructures are social material arrangements that maintain objects and enable their use. We introduce a framework for the study of object infrastructures and illustrate it by drawing on the case of "maritime piracy". Providing a historical reconstruction of the infrastructures that produce piracy as an international object, we show that the growing proliferation of these infrastructures does not lead to an internal coherence of the object over time, but rather objectual fracturing and instability. We reveal how objects are often multiple rather than unitary. The article adds an important new dimension to the study of objects in International Relations.
Offshore wind energy production has seen a significant expansion in recent years. With technologies rapidly improving and prices dropping, it is now one of the key instruments in the green energy transition. The implications of offshore wind farm expansion for maritime security and ocean governance have, so far, received sparse attention in the literature. This article offers one of the first thorough analyses of the security of offshore wind farms and related installations, such as underwater electricity cables, energy islands, and hydrogen plants. The technical vulnerabilities of wind farm systems is reviewed and threats from terrorism, crime and State hostilities, including physical and cyber risk scenarios, are discussed. The expansion of green offshore energy production must keep pace with the changing threat landscape that follows from it. Prospective solutions for the protection of wind farms systems, including surveillance, patrols and self-protection are discussed. The current repertoire of maritime security solutions is in many ways capable of dealing with the threats and risks effectively if adjusted accordingly. The analysis builds important new bridges between debates in energy security and maritime security, as well as the implications of climate change adaption and mitigation for security at sea.
Illicit maritime activities generate significant scholarly and policy attention. While diverse in nature, governance responses share many regulatory features. This introduction advances the notion of maritime justice, a socio‐legal research agenda. Different from broader maritime security studies, it places law at the centre of the inquiry, studying maritime governance practices through the lens of regulation. Empirically, it covers operational, spatial, and structural junctions between illicit maritime activity and regulatory responses deriving from international and domestic law. Analytically, it is heterogeneous but holds a methodological commitment to studying everyday law enforcement practices of maritime security governance to disentangle its meanings and effects. The introduction posits the junction between illicit maritime activities and regulatory responses as a productive space to study the varied norms that shape order‐making at sea, and vice versa.
Using evidence from 25,250 records of vessels entering and clearing the rivers of the Chesapeake Bay, this article demonstrates that intercolonial trading captains and crews significantly reduced the number of days their vessels spent in port in Virginia between 1698 and 1766. This contraction reflected a quantifying ethos in shipping that emerged during the early age of sail as the result of mutually reinforcing legal requirements and management practices. Responding to these productivity pressures, captains embraced practices that limited sailors’ freedom and turned to enslaved sailors to guarantee their maritime labor force. Embracing unfreedom aided captains to realize the dispatch goals that helped guarantee their investors’ returns.
As the world collectively looks to technology to salvage what is left of our world to sustain a habitat that can accommodate our way of life, users are increasingly exposed to technological solutions, rarely developed with an offset in their practice. This also holds for the maritime sector in Denmark, where the way of developing technology is limited to the applicability of technological artifacts and can reduce the potential efficiency gains that technologies can introduce. This paper applies qualitative research to show that there is a disconnect between, on the one hand, funders, technology developers, and decision-makers and, on the other hand, technology users and practitioners in the Danish maritime sector. It argued that if technology is to replace or assist any human practice and solve for example the climate crises, then knowledge of users’ practices must be key to developing the technological solutions.