Background
The aim of the study was to examine occupational accidents reported from non-passenger merchant ships registered in the Danish International Ship Register in 2010-2012, with a focus on analysing nationality differences in the risk of getting injured in an accident.
Methods
Data about notified occupational accidents were collected from notifications sent to the Danish Maritime Authority and from records of contact with Danish Radio Medical. Events were matched by personal identification and accident data to create a unified database. Stratified cumulative time spent on board by seafarers was used to calculate accident rates. Incidence rates of different nationalities were compared by Poisson regression.
Results
Western European seafarers had an overall accident rate of 17.5 per 100000 person-days, which proved to be significantly higher than that of Eastern European, South East Asian and Indian seaman (adjusted incidence rate ratio 0.53, 0.51 and 0.74, respectively), although differences decreased over the investigated period. Smaller but in most cases still significant discrepancies were observed for serious injuries. The back injury rate of Western European employees was found especially high, while eye injuries seem to be more frequent among South East Asian workers.
Conclusions
The study identified substantial differences between nationalities in the rate of various accidents reported from merchant ships sailing under the Danish flag. The differences may be attributed to various factors such as safety behaviour. Investigation of special injury types and characterisation of effective elements of safety culture can contribute to the improvement of workplace safety in the maritime sector
The latest IPCC report on Ocean and Cryosphere in a Changing Climate, which builds upon previous IPCC's reports, established a causal link between anthropogenic impacts and ocean acidification, by noting a significant decrease in the Ocean's uptake of CO2, with consequent damage to Earth's ecosystems, which in turn has traceable repercussions on the Arctic Ocean and then from the Arctic to the Planet Earth. The impact of ocean acidification is not only in the biological ecosystem but also on human activities, such as livelihood, food security, socio-economic security and developing communities. However, who can possibly be held ethically/legally responsible for ocean acidification from a climate justice perspective? Since what happens in the Arctic does not stay there, a more systematic law and policy approach to study options and responses in a multi-level, climate-ethical, global perceptive is needed. This paper sheds light on the legal responses available at global, regional and national levels to ocean acidification in a law of the sea and ocean context, both in the Arctic and from the Arctic. The gaps in legal and policy responses in connection to the ethical climate component will be identified. It will shed light on the planetary limits that humanity needs to stay within in order to maintain the future of the Earth. Since it touches upon questions of legal responsibility, on who is responsible for ocean acidification, it will connect to the “supply side” of fossil fuels production and global extraction projects causing anthropogenic CO2 emissions, one of the major causes of ocean acidification. It will also identify which actors, be they "officials" or "non-officials" (such as international organizations, states, regional institutes, Arctic citizens or even forums) should be held ethically responsible, and who should take action.
The International Energy Agency Technology Collaboration Program for Ocean Energy Systems (OES) initiated the OES Wave Energy Conversion Modeling Task, which focused on the verification and validation of numerical models for simulating wave energy converters (WECs). The long-term goal is to assess the accuracy of and establish confidence in the use of numerical models used in design as well as power performance assessment of WECs. To establish this confidence, the authors used different existing computational modeling tools to simulate given tasks to identify uncertainties related to simulation methodologies: (i) linear potential flow methods; (ii) weakly nonlinear Froude–Krylov methods; and (iii) fully nonlinear methods (fully nonlinear potential flow and Navier–Stokes models). This article summarizes the code-to-code task and code-to-experiment task that have been performed so far in this project, with a focus on investigating the impact of different levels of nonlinearities in the numerical models. Two different WECs were studied and simulated. The first was a heaving semi-submerged sphere, where free-decay tests and both regular and irregular wave cases were investigated in a code-to-code comparison. The second case was a heaving float corresponding to a physical model tested in a wave tank. We considered radiation, diffraction, and regular wave cases and compared quantities, such as the WEC motion, power output and hydrodynamic loading.
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 energy hubs connect large amounts of offshore wind to a hub from where the generation can be transmitted to onshore, potentially linking to multiple surrounding countries. The benefits of such hubs, and the related meshed offshore grid to connect them, have been investigated in the North Sea. The system-wide impacts of offshore energy hubs in the Baltic Sea are less studied; however, the region is seeing increased interest in offshore wind development. This paper uses detailed offshore wind generation simulations and energy system optimisation to investigate the cost-effectiveness of offshore energy hubs in the Baltic Sea in different scenarios towards 2050. The results show that the largest deployment of offshore energy hubs occurs when the energy system is highly electrified. The strongest development of the offshore energy hubs occurs in the southern part of the Baltic Sea.
The power output from many wave energy converters (WECs) is limited by a finite stroke length in the power take-off (PTO) mechanism. As the PTO approaches its maximum stroke length, an end-stop system needs to be engaged to avoid damage to the machinery. Still the on-set of the end-stop is a nonlinear trigger force, a stiff point in the system. In this respect it is similar to how snap loads in the mooring cables affect the system after a period of cable slack. This paper presents a detailed study into the dynamics of end-stop events and snap loads for a WEC. The WEC is a bottom-mounted linear generator connected to a surface buoy via a steel wire. By comparing a linear spring model with three dynamic mooring line models we conclude that large differences are observed in the low-tension and slack regions of the cable during moderate wave loads, while minor differences are seen in the estimated peak tension. By further varying end-stop parameters we observe that the peak tension in the line changes mildly with the axial stiffness for moderate wave heights. The peak tension is surprisingly unaffected by the introduction of a critical damping level to the end-stop system, despite the significant increase in end-stop force which causes the translator to come to a sudden stop. We discuss how the connection between maximum line force and end-stop parameters is highly dependent on the buoy position in the wave at the instant of end-stop onset.
The present paper describes the work carried out in the project ’Mooring Solutions for Large Wave Energy Converters’, which is a Danish research project carried out in a period of three years from September 2014, with the aim of reducing cost of the moorings for four wave energy converters and improving the applied design procedure. The paper presents the initial layouts and costs and illustrates which solutions could potentially reduce cost. Different methods for analysis of the systems were applied, ranging from simple quasi-static analysis to full dynamic analysis and experimental work. The numerical methods were compared to the experimental data, and results showed significant underestimation of tensions in the quasi-static model while reasonable overestimation was found in the dynamic analysis even without major tuning of the model. The dynamic analysis has then been implemented in a meta-model based optimization process with the aim of optimizing the mooring layout for each WEC according to cost of the systems.
Computational fluid dynamics (CFD) is becoming an increasingly popular tool in the wave energy sector, and over the last five years we have seen many studies using CFD. While the focus of the CFD studies have been on the validation phase, comparing numerically obtained results against experimental tests, the uncertainties associated with the numerical solution has so far been more or less overlooked. There is a need to increase the reliability of the numerical solutions in order to perform simulation based optimization at early stages of development. In this paper we introduce a well-established verification and validation (V&V) technique. We focus on the solution verification stage and how to estimate spatial discretization errors for simulations where no exact solutions are available. The technique is applied to the cases of a 2D heaving box and a 3D moored cylinder. The uncertainties are typically acceptable with a few percent for the 2D box, while the 3D cylinder case show double digit uncertainties. The uncertainties are discussed with regard to physical features of the flow and numerical techniques.
A serious ship-bridge collision accident happens about once a year. These accidents cause fatalities and large economic losses due to loss of transportation service and replacement cost of the bridge structure. One of the most recent, widely published, ship-bridge collisions was the collision where the containership Dali in 2024 collided with the Baltimore Key Bridge in the US city of Baltimore. The resulting collapse of the bridge girder caused six fatalities as well as large financial losses. One effect of this event has been that engineers around the world now are being engaged in evaluation of the vulnerability of existing bridges and establishment of rational design criteria for new bridges.
The presentation will outline elements of a rational design procedure for bridge structures against ship collision impacts. A set of risk acceptance criteria will be proposed and a mathematically based procedure for calculation of the probability of ship collision accidents caused by human as well as technical errors will be presented. This first part of the presentation leads to identification of the largest striking ship, “design vessel”, a given bridge element must withstand without structural failure in order for the bridge connection to fulfil the risk acceptance criteria.
The final part of the presentation will be devoted to an analysis of the needed impact capacity for the bridge pylons and piers exposed to ship bow impact loads from design vessels. A procedure will be described for derivation of expressions for ship bow crushing forces, which can be used in design against ship collision impacts. The resulting collision force expressions are verified by comparison with large-scale laboratory experiments and an analysis of a fullscale shipping accident. Finally, the proposed impact force expressions will be compared with existing standards for modelling ship collisions against bridges as published by AASHTO, IABSE and Eurocode.
Recent times have seen a great interest on environmental issues and efficient, sustainable systems. This interest has required the employment of advanced composites for a myriad of industrial machines and innovative equipments. Among these applications, Flywheel Energy Storage Systems – FESS – represent a group of machines that are being re-invented through this process. Modeling composite flywheels has proven to be a complex task, which current Finite Element models fail to fulfill in a number of design contexts. This demand to model complex composite geometries and systems induced the proposition of new methods, aiming to capture the various physical effects existing in the problem. In the present contribution, the authors consider that it is viable to model the dynamic behavior of a Flywheel Energy Storage System via an adapted Carrera Unified Formulation, both in terms of accuracy and computational cost, for practical applications. The present work presents and explores a Carrera Unified Formulation model with extended capabilities dedicated to rotordynamics applications. The differences from standard Finite Elements models are presented, evidencing advantages and drawbacks of the proposed methodology over more traditional approaches. A case study is then presented, modeled, and the results are compared with those stemming from established formulations.