In this paper speed optimization of an existing liner shipping network is solved by adjusting the port berth times. The objective is to minimize fuel consumption while retaining the customer transit times including the transhipment times. To avoid too many changes to the time table, changes of port berth times are only accepted if they lead to savings above a threshold value. Since the fuel consumption of a vessel is a non-linear convex function of the speed, it is approximated by a piecewise linear function. The developed model is solved using exact methods in less than two minutes for large instances. Computational experiments on real-size liner shipping networks are presented showing that fuels savings in the magnitude 2–10% can be obtained. The work has been carried out in collaboration with Maersk Line and the tests instances are confirmed to be representative of real-life networks.
Major liner shipping companies offer pre- and end-haulage as part of a door-to-door service, but unfortunately pre- and end-haulage is frequently one of the major bottlenecks in efficient liner shipping due to the lack of coordination between customers. In this paper, we apply techniques from vehicle routing problems to schedule pre- and end-haulage of containers, and perform tests on data from a major liner shipping company. The paper considers several versions of the scheduling problem such as having multiple empty container depots, and having to balance the empty container depot levels. The influence of the side constraints on the overall cost is analysed. By exploring the fact that the number of possible routes in the considered case is quite limited, we show that the model can be solved within a minute by use of column enumeration. Alternative constraints and problem formulations, such as balancing empty container storage level at depots, are considered. Computational results are reported on real-life data from a major liner shipping company.
We approach questions of Arctic marine resource economic development from the framework of environmental and resource economics. Shipping, fishing, oil and gas exploration and tourism are discussed as evolving industries for the Arctic. These industries are associated with a number of potential market failures which sustainable Arctic economic development must address. The varying scales of economic activity in the region range from subsistence hunting and fishing to actions by wealthy multinational firms. The ways in which interactions of such varied scales proceed will determine the economic futures of Arctic communities and the natural resources and ecosystems upon which they are based.
In this reported work, multi-dimensional computational fluid dynamics studies of diesel combustion and soot formation processes in a constant volume combustion chamber and a marine diesel engine are carried out. The key interest here is firstly to validate the coupling of a newly developed skeletal n-heptane mechanism and a revised multi-step soot model using laser extinction measurements of diesel soot obtained at different ambient pressure levels in an optical accessible, constant volume chamber experiment. It is revealed that ignition delay times and liftoff lengths generated using the new skeletal model are close to those produced by the larger and more comprehensive chemical mechanisms, apart from those at the low pressure condition. The current study also demonstrates that the variation of averaged soot volume fraction with respect to the change of combustion chamber pressure captured using the revised soot model agrees reasonably well with the measurements in terms of peak values. The numerical model is subsequently applied to investigate the flame development, soot/nitrogen monoxide formation and heat transfer in a two-stroke, low-speed uniflow-scavenged marine diesel engine operating at full load condition, where optical measurements are not available. Comparisons to the experimental data show that the simulated pressure rise starts 1.0 crank angle degree in advance and the calculated peak pressure is 1.7% lower. The associated flame liftoff length is negligible, yielding higher local equivalence ratio and soot volume fraction values as compared to those under similar test condition in the constant volume chamber. With the use of the revised model, the total heat transfer to the walls calculated when soot radiative heat loss is taken into account is approximately 30% higher compared to that when only convective heat loss is considered. The averaged nitrogen monoxide concentration is 7.7% lower when both convective and soot radiative heat losses are accounted for but the net soot mass production is less sensitive to soot radiation. A sensitivity study reveals that neither increasing nor decreasing the soot absorption coefficient by 30% from the baseline setup is influential to nitrogen monoxide formation, soot mass production and heat transfer. The findings here aid to gain insights and provide a better understanding of the combustion and soot processes in large, uniflow-scavenged marine engines. The numerical model developed in this work can also be applied to explore different phenomena in this combustion system.
As of January 2015, the new maximum limit of fuel sulfur content for ships sailing within emission control areas has been reduced to 0.1%. A critical decision for ship owners in advance of the new limits was the selection of an abatement method that complies with the regulations. Two main options exist: investing in scrubber systems that remove sulfur dioxide emissions from the exhaust and switching to low-sulfur fuel when sailing in regulated waters. The first option would involve significant capital costs, while the latter would lead to operating cost increases because of the higher price of the fuel used. This paper presents a literature review of emissions abatement options and relevant research in the field. A cost–benefit methodology to assess emission reduction investments from ship owners is also presented. A study examined the effects of recent drops in bunker fuel price to the payback period of a potential scrubber investment. The results show that lower prices would significantly delay the payback period of such investments, up to two times in some cases. The case studies present the emissions generation through each option for representative short sea shipping routes. The repercussions of low-sulfur policies on large emission reduction investments including cold ironing are examined, along with implications of slow steaming for their respective payback periods. Recommendations are made for research in anticipation of future regulations and technological improvements.
This study compares the details and performance of fisheries management between the EU and a selection of other countries worldwide: Iceland, New Zealand, and Australia, which are considered in many respects to be among the most advanced in the world in fisheries management. Fisheries management in the EU, Iceland, Australia, and New Zealand has developed following different paths, despite being based on similar instruments and principles. Iceland, Australia, and New Zealand have been at the forefront of developing management practices such as stakeholder involvement, legally binding management targets (Australia, New Zealand), individual transferable quotas, and discard bans (Iceland, New Zealand). The EU has since the beginning of the 21st century taken significant steps to better involve stakeholders and establish quantitative targets through management plans, and a landing obligation is gradually being implemented from 2015 onwards. The management of domestic fisheries resources in Australia, New Zealand, and Iceland has, overall, performed better than in the EU, in terms of conservation and economic efficiency. It should, however, be stressed that, compared to Australia, New Zealand, and Iceland, (i) initial over‐capacity was more of an issue in the EU when management measures became legally binding and also that (ii) the EU has been progressive in developing common enforcement standards, on stocks shared by sovereign nations. The situation of EU fisheries has substantially improved over the period 2004–2013 in the northeast Atlantic, with fishery status getting close to that in the other jurisdictions, but the lack of recovery for Mediterranean fish stocks remains a concern.
Due to increasing container traffic and mega-ships, many seaports face challenges of huge amounts of truck arrivals and congestion problem at terminal gates, which affect port efficiency and generate serious air pollution. To solve this congestion problem, we propose a solution of managing truck arrivals with time windows based on the truck-vessel service relationship, specifically trucks delivering containers for the same vessel share one common time window. Time windows can be optimized with different strategies. In this paper, we first propose a framework for installing this solution in a terminal system, and second develop an optimization model for scaling time windows with three alternative strategies: namely fixed ending-point strategy (FEP), variable end-point strategy and greedy algorithm strategy. Third, to compare the strategies in terms of effectiveness, numerical experiments are conducted based on real data. The result shows that (1) good planning coordination is essential for the proposed method; and (2) FEP is found to be a better strategy than the other two.
This article investigates how speakers in maritime technologically mediated interaction utilize pre-scripted interaction. The analysis uses micro-analytical methods that have not been used in the analysis of maritime interactions since the study by Bailey et al. (2006). In contrast to Bailey et al. (2006) who have analysed interactions between co-located speakers on board ships, this article analyses interactions between speakers who are not co-located. Micro-analytical methods can shed light on sense-making practices that speakers display in pre-scripted user-device interaction as pointed out by Arminen (2005). The article advances the observations of Bailey et al. (2006) regarding the ‘confirmatory form’ that they found predominant in co-located bridge team interaction. A ‘confirmatory form’ is a speaker display of the pre-script1 called a ‘readback’ (IMO SMCP, 2001), that speakers show when verifying information. The analysis shows that the structure of the ‘readback’ is used by speakers, is dependent on reflexive user-device interaction and involves a situated rule-following (Wittgenstein, 1958). The article then argues against the findings in The MARCOM Project (1999) that advocates that spoken interaction should be done away with completely as a way of promoting safe navigation, and concurs with studies in aviation research, that show how verbal interaction is an essential part of the situated understanding that takes place when performing institutional tasks (Sanne, 2003; Nevile, 2004a; Falzon, 2008, 2009).
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.