A 3D fully nonlinear potential flow (FNPF) model based on an Eulerian formulation is presented. The model is discretized using high-order prismatic – possibly curvi-linear – elements using a spectral element method (SEM) that has support for adaptive unstructured meshes. The paper presents details of the FNPF-SEM development and the model is illustrated to exhibit exponential convergence. The model is then applied to the case of focused waves impacting on a surface-piecing fixed FPSO-like structure. Good agreement was found between numerical and experimental wave elevations and pressures.
Successful maritime spatial planning processes require stakeholder engagement and participation, thus requiring tools that support collaboration. Communication-driven spatial decision support systems are designed to facilitate decision making processes of complex spatial problems and are therefore suited for this task, but there are unresolved questions about user access control for these systems. In this study, user access control was designed for a spatial decisions support system for collaborative maritime spatial planning based on observation of two user tests. It was found that there were three distinct groups of users with special access needs to collaborative functionality. The level of access to functionality was organized into three groups: passive participants, actively contributing collaborators and managing moderators.
Multi-phase flow meters are of huge importance to the offshore oil and gas industry. Unreliable measurements can lead to many disadvantages and even wrong decision-making. It is especially important for mature reservoirs as the gas volume fraction and water cut is increasing during the lifetime of a well. Hence, it is essential to accurately monitor the multi-phase flow of oil, water and gas inside the transportation pipelines. The objective of this review paper is to present the current trends and technologies within multi-phase flow measurements and to introduce the most promising methods based on parameters such as accuracy, footprint, safety, maintenance and calibration. Typical meters, such as tomography, gamma densitometry and virtual flow meters are described and compared based on their performance with respect to multi-phase flow measurements. Both experimental prototypes and commercial solutions are presented and evaluated. For a non-intrusive, non-invasive and inexpensive meter solution, this review paper predicts a progress for virtual flow meters in the near future. The application of multi-phase flows meters are expected to further expand in the future as fields are maturing, thus, efficient utilization of existing fields are in focus, to decide if a field is still financially profitable.
Maritime security capacity-building is a growing field of international activity. It is an area that requires further study, as a field in its own right, but also as an archetype to develop insights for capacity-building and security sector reform in other arenas. This article is one of the first to analyse this field of activity. Our empirical focus is on the Western Indian Ocean (WIO) region. Here, international actors have launched multiple capacity-building projects, initially in response to Somali piracy. We document the significance, extent and variety of capacity-building activities in this region and examine the ways in which capacity-building at sea has incorporated innovative characteristics that develop and expand the capacity-building agenda as traditionally understood. Our conclusion highlights the need to pay more attention to the maritime domain in international security and development studies and considers ways in which the maritime capacity-building experience may offer important lessons for other fields of international policy.
With international rules of navigation, the IMO COLREGS, describing the regulatory behaviours of marine vessels relative to each other, correct interpretation of situations is instrumental to the successful navigation at sea. This becomes even more crucial when temporal unattended bridge or fully unmanned navigation is aimed at. Based on a breakdown of COLREG rules, this paper presents a framework for representation of manoeuvering behaviours, that are expected when all vessels obey the rules. Our analysis is based on discrete-event systems theory and the proposed framework consists of sets of finite automata, segregating situation assessment from decision making. A intermediate supervisory layer coordinates the communication of these automata modules. The framework is tested in simulation environment using a realistic scenario.
For more than a century, conventional marine vessels spatter the atmosphere with CO2 emissions and detrimental particles when operated by diesel motors/generators. Fuel cells have recently emerged as one of the most promising emission-free technologies for the electrification of ship propulsion systems. In fuel cell-based ship electrification, the entire marine power system is viewed as a direct current (DC) microgrid (MG) with constant power loads (CPLs). A challenge of such settings is how to stabilize the voltages and currents of the ship’s grid. In this paper, we propose a new modified backstepping controller to stabilize the MG voltage and currents. Finally, to study the performance and efficiency of our proposal, we run an experiment simulation using dSPACE real-time emulator.
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.
Rigid fisheries management frameworks often leave fishermen with limited possibilities and incentives to adjust the selectivity of their gears to the specific fishing conditions. Implementation of the landing obligation in European fisheries emphasizes fishermen's need for flexibility in which gear to use to be able to match the selectivity of the gear to the quota available. How fishermen can play an important role in facilitating a more regionalised and flexible technical regulation by actively participating in the development of gears and contributing to the scientific documentation of their selectivity is discussed. Perspectives in the proposed technical regulation for EU fisheries and the regionalization in the 2013 Common Fisheries Policy are discussed based on an analysis of the current EU technical regulation. Then a new pathway to address the problem, currently being trialled in Danish fisheries, is discussed. Throughout the article, three themes are discussed: Identifying gear needs, development and testing of gear with fishermen as central actors; how the selectivity of the gear should be documented; and opportunities for faster evaluation of new gear, following the regionalization of the technical measure regulation. The paper concludes that a more flexible system of gear development and evaluation is possible by a) involvement of fishermen in proposing gear adjustments, self-sampling and documenting results following scientific protocols and evaluation, testing a range of designs before scientific testing, and b) open for faster approval of gear use under a regionalized technical regulation regime with annual adjustments of management plans containing the technical regulation.
The port industry is in a state of flux which is affecting the roles of port authorities. Applying a business model perspective to explore this qualitative shift in competition, this paper argues that port authorities are increasingly managing multiple multilateral business models. This is analyzed through an integrative review of port research which identifies four challenges for port authorities: 1) diversification of port customers; 2) requirements for new value creation; 3) changing possibilities and constraints of value capture; and 4) network effects, clusters and strategic partnerships. The review contributes to literature by exploring how managing port authority business model innovation requires changing the underlying business logic, the activities and resources and the configurational fit with other port actors' business models. This proposition is based on the interplay between the macro level port industry, the meso level rule structures within port systems and the micro level of port authority organisations.
The space occupied by traditional and new human-based marine uses at sea is expanding, creating a need for developing methods to assess interactions between co-located uses in maritime spatial planning (MSP). However, no clear terminology for use-use interactions exists. Thus, an analytical framework for spatial decision support tools (DSTs) to assess use-use interactions is deduced from literature. Four spatial-temporal links are found to either alone or together constitute use-use interactions: location links, environmental links, technical links, and user attraction links. It is found to be important for DSTs to support co-location management in MSP by iteratively through the MSP process 1) spatially-temporally locate spatial-temporal links constituting use-use interactions, 2) list conflicts and synergies of the located use-use interactions, and 3) weight the conflicts and synergies. With this analytical framework, two types of DSTs are analysed for their ability to include co-location; matrix- and ranking-based DSTs to detect conflicts and synergies and space allocating DSTs to avoid/minimise conflicts and optimise synergies. Whereas the first group of tools categorise or rank use-use combinations, the latter group use information about which multi-use combinations are possible as pre-existing knowledge, and thus the two groups of DSTs can advantageously be used together. A discrepancy is found between the co-location framework and the DSTs. It is argued that future tools could work on removing this discrepancy by considering the spatial-temporal links of use-use interactions, strengthen the focus on synergies, as well as prioritize ranking of synergies and conflicts over binary approaches that only evaluate spatial compatibility.