Knowledge

Once known as an example of state collapse, Somali territories today see a number of competing public administrations, which, as this book argues, depend on a dynamic trade sector for revenues. Riffing on Tilly’s idea that ‘war makes states,’ the authors argue instead that ‘trade makes states,’ that the facilitation and capture of commodity flows have been instrumental in making and unmaking state-projects across the Somali territories. The volume draws on multi-sited research of everyday economic life along trade corridors in Somali East Africa, including parts of Kenya and Ethiopia. It examines how government officials, informal traders, militias, local businessmen, international investors, and donors feed into systems of regulatory control in ports, at marketplaces, and along transport corridors. Contributions to the volume draw attention to the ingenuities of transnational Somali trade and the ‘politics of circulation,’ providing important insights into contemporary state formation on the margins of global supply chain capitalism.

The implementation of unmanned vessels will evidently come with its own legal challenges. One of the most crucial of these is the identification of the role and status of the shore-based controller (SBC) for the purposes of determining liability. Different liability regimes apply different legal principles in this regard. This article will explore these issues from the perspective of English law and Scandinavian law.

The energy system needs a range of forecast types for its operation in addition to the narrow wind power forecast that has been the focus of considerable recent attention. Therefore, the group behind the former IEA Wind Task 36 Forecasting for Wind Energy has initiated a new IEA Wind Task with a much broader perspective, which includes prospective interaction with other IEA Technology Collaboration Programmes such as the ones for PV, hydropower, system integration, hydrogen etc. In the new IEA Wind Task 51 (entitled "Foreacsting for the Weather Drive Energy System") the existing Work Packages (WPs) are complemented by work streams in a matrix structure. The Task is divided in three WPs according to the stakeholders: WP1 is mainly aimed at meteorologists, providing the weather forecast basis for the power forecasts. In WP2, the forecast service vendors are the main stakeholders, while the end users populate WP3. The new Task 51 started in January 2022. Planned activities include 4 workshops. The first will focus on the state of the art in forecasting for the energy system plus related research issues and be held during September 2022 in Dublin. The other three workshops will be held later during the 4-year Task period and address (1) seasonal forecasting with emphasis on Dunkelflaute, storage and hydro, (2) minute-scale forecasting, and (3) extreme power system events. The issues and conclusions of each of the workshops will be documented by a published paper. Additionally, the Recommended Practice on Forecast Solution Selection will be updated to reflect the broader perspective.

This work presents a comparative study of two signal processing methods for the estimation of the roll natural frequency towards the real-time transverse stability monitoring of fishing vessels. The first method is based on sequential application of the Fast Fourier Transform (FFT); the second method combines the Empirical Mode Decomposition (EMD) and the Hilbert-Huang Transform (HHT). The performance of the two methods is analysed using roll motion data of a stern trawler. Simulated time series from a one degree-of-freedom nonlinear model, and experimental time series obtained from towing tank tests are utilized for the evaluation. In both cases, beam waves are considered but, while irregular waves are adopted in the simulated data, the towing tank tests are made in regular waves. Based on the available data the performance of both estimation methods is comparable, but the EMD-HHT method turns out slightly better than the sequential FFT. Finally, the use of a statistical change detector, together with the EMD-HHT methodology, is proposed as a possible approach for the practical implementation of an onboard stability monitoring system.

This PhD thesis examines the role of market-based measures (MBMs) in incentivizing international shipping greenhouse gas (GHG) emissions reductions to leverage the decarbonization efforts of the International Maritime Organization (IMO). The research motivation sprang from the Initial IMO Strategy, which, among other climate ambitions, envisages at least a 50% curb of GHG emissions until 2050 vis-a-vis 2008 levels. The regulatory framework involves several candidate measures, including MBMs, i.e., environmental policies like carbon taxes and emissions trading systems (ETS) that enforce the "polluter-pays" principle, and thus provide fiscal incentives to stakeholders to eliminate their carbon footprint.

The assessment of MBMs as means of decarbonizing shipping is based on three main pillars: their economic efficiency, their environmental effectiveness, and their climate policy design. Compliance with carbon pricing regimes can entail the adoption of both operational measures, such as speed reduction, route reconfiguration, or voyage optimization techniques, and technological measures like the uptake of zero-carbon technologies and alternative marine fuels. Due to this wide range of conformity practices, this thesis assesses several short- and long-term responses to MBMs in order to encapsulate their cost effectiveness in relation to their carbon abatement potential.

From a climate policy design perspective, the two most prominent types of MBMs are the carbon taxes, a fixed-price approach that provides carbon price certainty, and the ETSs, a fixedquantity system that secures that GHG emissions levels are met. At first, the study evaluates the prospects of a carbon levy to achieve GHG emissions reductions by analyzing the macroeconomic effects of freight rates and fuel prices in inducing slow steaming as an operational response to the MBM. The results show that market conditions influence the overall effectiveness of a tax and that the attained reductions, although significant, are insufficient to reach the 50% decarbonization targets. Moreover, considering the imminent inclusion of the maritime sector into the EU ETS, the thesis examines the scenario of liner shipping operators opting for route reconfigurations as an operational response to a regional ETS. The outputs reveal that replacing EU ports with nearby non-EU competitor ports becomes cost-effective for minimal EU carbon prices. The action would result in carbon leakage, EU ETS evasion, loss of EU ETS revenue, and penalization of the EU ports.

To the extent that MBMs induce technological changes, this thesis evaluates the level of carbon pricing needed to close the price gap between alternative and conventional marine fuels. The analysis considers the capital and operational costs for implementing and utilizing alternative marine fuels onboard and develops their marginal abatement cost curves (MACCs) to evaluate their cost-competitiveness and carbon abatement spectrum. The analysis indicates that to reach full maritime decarbonization, fuels such as green liquid hydrogen and their supporting technology, as of today’s cost estimations, would require a carbon price of up to 700 USD/MT CO2e to become cost-competitive.

The thesis concludes that accounting for a well-to-wake scope of emissions will create the right
incentives for developing sustainable alternative marine fuel production pathways to facilitate
shipping’s future energy demand. Revenues from MBMs will be substantial and can accelerate
R&D, scale-up the availability of alternative fuels, subsidize "fist-movers" and green ships and
reverse possible detrimental effects of carbon pricing to developing countries such as the Least
Developed Countries (LDCs) and the Small Island Developing States (SIDS).

In a new book, senior researcher Jessica Larsen analyses how relevant anti-piracy legislation was enforced when international ship contributions and regional coastal states cooperated on anti-piracy off the coast of Somalia in 2008-2016.

The book is a socio-legal study based on both clause analyses and ethnographic fieldwork. The book takes the reader on board a warship patrolling the Indian Ocean and into the courtrooms of the island nation of Seychelles, which conducted 17 piracy cases. Through interviews and observations, the book uncovers how anti-piracy legislation works in practice. Existing studies have primarily examined existing law. This book goes out into the field to also uncover applied law.

The analysis shows examples of ambiguity about which legal sources should be applied at sea. It identifies practices in court that show cases of impunity and questions legal certainty. The implications of this should be considered as counter-piracy off Somalia has been used as a model for counter-piracy elsewhere, such as in the Gulf of Guinea.

Offshore jacket foundations for wind turbine generators are in risk of metal fatigue at the weldedjoints due to the highly dynamic wind and wave loading. The complex multiaxial stresses occurringat the welded joints can be non­proportional and lead to increased fatigue damage as compared toproportional stresses. Furthermore, several random effects influence the response of the offshorestructures and the fatigue lives of the welded joints.

In this thesis, the fatigue response of welded joints in offshore jacket structures is assessed. The influence of non­proportional stress states on the fatigue life has been examined using experimental fatigue data from literature by modelling the published experiments using the finite element method (FEM) and assessing the stress states using the notch stress approach. The results show that a nonzero phase­shift between the governing normal and shear stress at the weld toe leads to increased damages at the weld. An approach for determining the non­proportionality penalty factors for obtaining correct fatigue life estimations has been proposed.

To quantify the level of non­proportionality in the stress states at welds a new quantification approach has been developed based on the principal component analysis (PCA). The approach is easy to implement and simple to interpret, which is often difficult for many of the already published methods. The PCA­based approach is furthermore extended to be used with variable amplitude stress states. By implementing the developed quantification approaches in the fatigue life calculation framework, it is possible to determine if non­proportionality occurs and to account for this in the fatigue life estimation automatically using the estimated penalty factors.

The stochastic finite element method (SFEM) has been used to implement approaches for considering the spatial variability occurring in the jacket structures and welds. Closed­form solutions to the stochastic stiffness and stress stiffness matrices have been proposed, making it possible to easily implement the spatial variability of the bending rigidity and other parameters in beam FE models. The matrices have been developed for both classical Euler­Bernoulli and Timoshenko beam theory and are based on the Karhunen­Loéve (KL) expansion for random field discretization. The KL expansion is then further used to formulate a stochastic size effect that takes into account that longer welds tend to fail earlier than shorter welds when considering fatigue. Other approaches for taking into account the size effect are often based on statistical evaluation of fatigue experiments which is used to determine a deterministic calibration factor. The stochastic size effect makes it possible to simulate the randomness in a full weld independently of the highest stressed zones. Using this method, the quality of the welding can be simulated and used to predict more accurate fatigue lives.

In order to design more fatigue resistant welded joints in offshore jacket structures, automatic optimization of the welded joints is required. Already published approaches to do so, often focus on only a few simple fatigue criteria. For an optimization framework to be efficient it has to take into account the complex multiaxial non­proportional fatigue and the stochastic effects of the welds. In the thesis, an optimization framework for fatigue life estimation using the developed PCA­based quantifier and the stochastic size effect has been developed. The framework is easy to use and based on simple formulations, making it possible to implement many types of fatigue criteria without having to reformulate the optimization procedure. The framework has been used to optimize the weld locations in a cast steel jacket insert and shows that considerable mass savings can be achieved by automatic
optimization.

The Gulf of Guinea (GoG) region is a vast maritime area off West and Central Africa, and an area of interest to numerous external actors for a range of different reasons including historical relations, trade, oil and fishery. This maritime space is characterised not only by legitimate actors’ presence at sea but also by various types of maritime criminality, with piracy currently being high on the agenda of external actors. Indeed, in 2020, 95% of all maritime kidnappings globally happened in the GoG. Through the application of a specific theoretical lens, namely the politics of piracy numbers, this chapter offers a regional case study of piracy in the GoG. Through this lens, the chapter for example explores how, though being the most counted type of maritime insecurity, piracy is only one aspect of a much broader complex of maritime insecurities. Attending also to the politics of missing numbers, the chapter also explores how far less attention is devoted to counting various onshore dimension of GoG-piracy.

The first-mile problem, which refers to the design of transport services that connect passengers to their nearby transit station, has attracted growing attention in recent years. In this paper we consider first-mile ride-sharing services and study the problem of optimally determining the fleet size and assigning vehicles to transport requests. We formulate the problem as a mixed-integer program and present a number of numerical experiments based on a small-scale system to analyse different configurations of the service, namely with and without fleet control (FC). Result shows that a configuration with FC is superior in terms of profits while service rates can be higher in a configuration without FC, depending on the revenue-sharing mechanism.

This thesis presents the numerical study of combustion under marine engine like condi- tions. The thesis is divided into two main parts. In the first part, combustion is studied in a large two-stroke marine engine with conventional diesel fuel. In the second part, two different dual-fuel combustion modes of diesel-methane i.e. non-premixed combus- tion and premixed combustion are studied. All numerical models are validated with the experimental data.
First, in a simplified geometry of the marine engine, conjugate heat transfer (CHT) calculations are applied to simultaneously solve the in-cylinder gas phase dynamics and the temperature field within the liner of the engine. The effects of different initial tem- peratures across the liner and the effects of the amount of water vapor in the air on the sulfuric acid formation and condensation in a large two-stroke marine engine are studied. An initial temperature is calculated based on heat transfer modeling and it is observed that the sulfuric acid vapor formation is more sensitive to the variation of the water vapor amount than the sulfuric acid condensation. In the next step, the effects of the turbulence modelling on the simulation of the full cycle of the engine including scavenging process, combustion, and emission formation is studied in a real geometry of a large two-stroke marine research engine. The Unsteady Reynolds Averaged Navier- Stokes (URANS) and Large Eddy Simulation (LES) turbulence models are utilized for modeling of in-cylinder turbulent flow. The accuracy of the tangential velocity and swirl flow in the top of the cylinder where the fuel is injected is crucial to predict the air-fuel mixing correctly. It is found that URANS predicts a solid body rotation for the tangential velocity in this region. However, LES predicts a tangential velocity that is uniformly distributed in the radial direction that is consistent with experimental results. Furthermore, during the scavenging process, LES is able to predict the Burgers vortex upstream of the cylinder near the scavenging ports. Also, LES predicts a higher angu- lar momentum inside the cylinder in comparison with URANS. During the combustion process, the LES model shows a moderately better performance in capturing the experi- mental pressure and heat release rate profiles than URANS. However, the predicted gas temperature at the liner wall is approximately 45 % higher for URANS than LES during the expansion stroke, which is attributed to a higher predicted turbulent viscosity in the URANS case. A higher temperature of gas beside the liner wall may decrease the sulfuric acid formation and increase the heat transfer. The higher predicted swirl by LES than that in URANS leads to an earlier and stronger interaction between the flame and the spray, decreasing the oxidation of the emissions. The second cycle LES simula- tion shows that the solutions after the scavenging process are in-sensitive to the initial conditions and the main governing parameters are boundary conditions and injection characteristics.
Next, two different dual-fuel combustion modes of non-premixed combustion and premixed combustion are studied. The non-premixed combustion is simulated and val- idated with the experimental data of a large two-stroke marine research engine under low and high engine loads. Based on the results, further methane jets penetration in the low load case leads to better air-fuel mixing and a higher combustion intensity than that in the high load. Effects of the pilot diesel fuel injection timing on combustion and emission formation and the governing mechanisms are also investigated in detail. Results indicate that the intense combustion of the accumulated methane expands the methane flame towards the piston when the pilot injection timing is retarded. The NO formation is lower in the high load case due to the lower combustion intensity. Also, retarding the pilot injection timing decreases the NO formation. Furthermore, the effect of the direction of pilot diesel injection is investigated which shows a significant effect on the methane start of combustion and intensity as well as flame propagation direction which leads to different heat transfer trends from the combustion chamber walls.
Premixed combustion is analysed in a constant volume combustion chamber (CVCC) and validated with experimental data. Results show that by simulation of methane-air mixing, the numerical model is able to capture the ignition delay time (IDT) within a maximum relative difference of 7 % to the measurements. A higher relative difference of 38% is obtained when methane gas injection is omitted and the methane-air and temperature are assumed homogeneous. Therefore, it is concluded that the simulation of methane-air mixing process is crucial in this type of combustion due to the presence of inhomogeneities in both methane fuel and temperature distribution after mixing. Creating the idealized inhomogeneities for separately investigation of methane and tem- perature inhomogeneities shows that the inhomogeneity in the temperature has a more profound influence on the IDT than the inhomogeneity in the methane distribution. Furthermore, the effects of the number of pilot fuel nozzle holes on the auto-ignition are studied. The auto-ignition process in two cases with 4 nozzle holes is investigated and compared with the base case with 8 nozzle holes. Considering the same amount of pilot fuel, the injection rate is assumed to be double in one of the cases, while in the other case, the injection duration is doubled. Results show that a reduction of the nozzle hole numbers can improve the pilot diesel ignition in the case with 4 nozzle holes and double injection duration compared to the base case with 8 nozzle holes. However, combustion in the case with 4 nozzle holes and a double injection rate is incomplete due to flame impingement on the walls.