Autonomous unmanned underwater vehicles (UUVs) play a vital role in diverse underwater operations; localization is of great interest for UUVs mirroring the trend seen in self-driving surface and aerial vehicles. Unlike their land and aerial counterparts, underwater environments lack reliable Global Navigation Satellite Systems (GNSS) due to radio wave attenuation in water. Hence, alternative localization methods are imperative for both navigation and operational purposes. This study thoroughly reviews sensor technologies for underwater localization, including sonar, Doppler velocity log, cameras, and more. Different operations necessitate distinct localization accuracies and vehicle and sensor choices. Environmental factors, such as turbidity, waves, and sound disturbances, impact sensor performance. Conclusions are given on the coincidence between operational requirements and sensor specifications, with special attention to the open concerns. These considerations include aspects such as the line of sight for acoustic positioning systems and the requirement for a feature-rich environment for visual sensors. Lastly, a prediction for the future of underwater localization is given, where the tendencies indicate lower costs for sensors, making operation-specific vehicles more attractive, which aligns with an increased demand for cost-efficient autonomous offshore operations.
A major part of the world fleet of more than 47,000 merchant ships operates under conditions that hamper energy efficiency and efforts to cut CO2 emissions. Valid and reliable data sets on ships' energy consumption are often missing in shipping markets and within shipping organizations, leading to the non-implementation of cost-effective energy efficiency measures. Policy makers are aiming to remedy this, e.g., through the EU Monitoring, Verification and Reporting scheme. In this paper, current practices for energy consumption monitoring in ship operations are explored based on interviews with 55 professionals in 34 shipping organizations in Denmark. Best practices, which require several years to implement, are identified, as are common challenges in implementing such practices—related to data collection, incentives for data misreporting, data analysis problems, as well as feedback and communication problems between ship and shore. This study shows how the logic of good energy consumption monitoring practices conflict with common business practices in shipping companies – e.g., through short-term vessel charters and temporary ship organizations – which in turn can explain the slow adoption of energy efficiency measures in the industry. This study demonstrates a role for policy makers or other third parties in mandating or standardizing good energy consumption monitoring practices beyond the present requirements.
This chapter introduces the reader to port State jurisdiction in public international law, linking customary law traditions to its utilization in the International Convention for the Prevention of Pollution from Ships (MARPOL). Its provisions are contextualized within their relationship to the United Nations Convention on the Law of the Sea, both historically as a matter of treaty negotiations, and contemporarily as a matter of defining generally accepted international rules and standards for port States regulating vessel-source pollution. Port States play a key role in promoting and evolving the uniform and universal application of MARPOL standards as, by-and-large, minimum global standards. Complementary principles—such as no more favorable treatment—and mechanisms—such as regional port State control memorandums—are highlighted, as well as several relevant implementation strategies, for example, concentrated inspection campaigns.
Long considered a cultural contact zone, the Mediterranean has become a weaponised border zone keeping refugees from Africa and the MiddleEast away from ‘Fortress Europe’. The Mediterranean has become excessively dangerous to cross, leading many commentators to call this maritime space a ‘massive graveyard’. The widespread indifference and enmity towards migrants in Europe is, amongst other things, countered by documentary and commemorative projects by artists drawing attention to the suffering of drowned refugees. In this paper, I zoom in on documentary and memorial artistic projects by Mimmo Paladino, Jason deCaires Taylor, Christoph Büchel, Ai Weiwei and Đỉnh Q. Lê. In the frequent absence of dead bodies and specific grave sites on the ‘high seas’, they make claims regarding the humanity, singularity and memorability of the human lives of refugees drowned at sea. Based on a description of the artworks and their public, I make two interlinked theoretical arguments. First, the commemorative materialisations by contemporary artists are temporal claims to constitute the cultural heritage of the future. Second, given the sea’s aquatic materiality, the commemorative claims of these art projects require that commemorative materialisations must spatially move from the flux of the sea to the fixity of the land.
Background:
The metabolic syndrome (MS) represents a cluster of risk factors related to insulin resistance. Metabolic syndrome is a strong risk factor for chronic metabolic and cardiovascular diseases and is related to nutritional factors, sleep patterns, work-related stress, fatigue, and physical activity — all of which are critical issues at sea. We have previously demonstrated a MS prevalence of 24.2% in Danish seafarers. This study aimed to follow the trend of MS after 2 years’ intervention.
Materials and methods:
Out of 524 Danish seafarers (mean age 37.7 years) who underwent medical fit-for-duty examination by seamen’s doctors at baseline, 141 seafarers (mean age 41.3 years) were tracked and re-examined after 2 years. At baseline all participants received general advice regarding lifestyle issues. Seafarers with MS were additionally given specific advice regarding treatment. The seafarers provided questionnaire information about their workplace on board, about treatment of hyperlipidaemia, hypertension, and about previously diagnosed type 2-diabetes. In order to define MS, we collected data about waist circumference, blood pressure, triglycerides, HDL-cholesterol, and fasting plasma glucose.
Results:
Out of 35 (26.5%) seafarers who fulfilled the criteria for MS at follow-up, 18 had MS at baseline while 9 were incident cases. Two seafarers with MS at baseline ceased to qualify for this condition at follow-up. The prevalence of seafarers with MS at follow-up represents a minimal estimate because a proportion could not be assessed due to missing fasting blood tests. Smoking and alcohol consumption was not reduced.
Conclusions:
In spite of the intervention, the prevalence of MS increased in this group of seafarers. This study indicates the limitations of individual health promotion and the need for corporate actions.
We consider a variant of the berth allocation problem-i.e., the multi-port berth allocation problem-aimed at assigning berthing times and positions to vessels in container terminals. This variant involves optimizing vessel travel speeds between multiple ports, thereby exploiting the potentials of a collaboration between carriers (shipping lines) and terminal operators. Using a graph representation of the problem, we reformulate an existing mixed-integer problem into a generalized set partitioning problem, in which each variable refers to a sequence of feasible berths in the ports that the vessel visits. By integrating column generation and cut separation in a branch-and-cut-and-price procedure, our proposed method is able to outperform commercial solvers in a set of benchmark instances and adapt better to larger instances. In addition, we apply cooperative game theory methods to efficiently distribute the savings resulting from a potential collaboration and show that both carriers and terminal operators would benefit from collaborating.
This chapter argues that state-owned Chinese integrated maritime logistics enterprises are about to change the power balance vis-à-vis the hitherto dominant, privately owned enterprises based in Europe. This shift, which has been actively supported as part of China’s ambitious Belt and Road Initiative, will directly affect the European Union’s common transport and competition policy. Within the larger Belt and Road Initiative, the Maritime Silk Road project can be seen as the umbrella concept for the comprehensive management of the entire supply chain between China and Europe. We discuss possible policy implications for both China and the European Union when it comes to managing the subtle balance between geopolitical considerations and efficient operations of trade and transport controlled by a few dominant actors. As part of our theoretical framework, we use two extensions of the classical obsolescing bargaining model: the one-tier bargaining model and a bargaining model of reciprocation. By combining the two models, we aspire to explain the changing nature of bargaining relations between, on the one hand, the Chinese government and its state-owned enterprises and, on the other, the private-owned European companies as a function of the goals, resources and constraints of the involved parties.
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.
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.