Most of the operational problems in container terminals are strongly interconnected. In this paper, we study the integrated Berth Allocation and Quay Crane Assignment Problem in seaport container terminals. We will extend the current state-of-the-art by proposing novel set partitioning models. To improve the performance of the set partitioning formulations, a number of variable reduction techniques are proposed. Furthermore, we analyze the effects of different discretization schemes and the impact of using a time-variant/invariant quay crane allocation policy. Computational experiments show that the proposed models significantly improve the benchmark solutions of the current state-of-art optimal approaches.
To improve the energy efficiency, the demand for new light-weight solutions has been increased significantly in the last decades. The weight reduction of the current ship structures is possible using thinner plates, that is, plate thickness between 3 and 4 mm. However, at present this is, in normal cases, not possible due to the 5 mm minimum plate thickness requirement given by classification societies. The present paper investigates the fatigue strength of thin-plated ship structures. In the European research project BESST – ‘Breakthrough in European Ship and Shipbuilding Technologies’ – the extensive fatigue test programme was carried out for butt- and fillet-welded specimens, which were manufactured by the arc, laser and laser-hybrid welding methods. The test programme also covered the different production quality and thus a large variation of misalignments was included. Fatigue test results were analysed using the nominal as well as the structural stress approach, where the actual geometry of the specimens was taken into account. The results show that the present design S–N curve with slope value of 3 is applicable to thin plates, but it is slightly non-conservative. The fatigue test results for thin plates show better agreement with the slope value of 5. For thin plates and slender ship structures, the secondary bending stress due to angular misalignment plays an important part and changes in a non-linear way with the applied tension load. Therefore, it is important to consider the plate straightening effect in structural stress analysis.
The optimal (economic) speed of oceangoing vessels has become of increased importance due to the combined effect of low freight rates and volatile bunker prices. We examine the problem for vessels operating in the spot market in a tramp mode. In the case of known freight rates between origin destination combinations, a dynamic programming formulation can be applied to determine both the optimal speed and the optimal voyage sequence. Analogous results are derived for random freight rates of known distributions. In the case of independent rates the economic speed depends on fuel price and the expected freight rate, but is independent of the revenue of the particular voyage. For freight rates that depend on a state of the market Markovian random variable, economic speed depends on the market state as well, with increased speed corresponding to good states of the market. The dynamic programming equations in our models differ from those of Markovian decision processes so we develop modifications of standard solution methods, and apply them to small examples.
Policy emphasis in ship design must be shifted away from global and idealized towards regional based and realistic vessel operating conditions. The present approach to reducing shipping emissions through technical standards tends to neglect how damages and abatement opportunities vary according to location and operational conditions. Since environmental policy originates in damages relating to ecosystems and jurisdictions, a three-layered approach to vessel emissions is intuitive and practical. Here, we suggest associating damages and policies with ports, coastal areas possibly defined as Emission Control Areas (ECA) as in the North Sea and the Baltic, and open seas globally. This approach offers important practical opportunities: in ports, clean fuels or even electrification is possible; in ECAs, cleaner fuels and penalties for damaging fuels are important, but so is vessel handling, such as speeds and utilization. Globally we argue that it may be desirable to allow burning very dirty fuels at high seas, due to the cost advantages, the climate cooling benefits, and the limited ecosystem impacts. We quantify the benefits and cost savings from reforming current IMO and other approaches towards environmental management with a three-layered approach, and argue it is feasible and worth considering.
The multi-commodity network flow problem is an important sub-problem in several heuristics and exact methods for designing route networks for container ships. The sub-problem decides how cargoes should be transported through the network provided by shipping routes. This paper studies the multi-commodity network flow problem with transit time constraints which puts limits on the duration of the transit of the commodities through the network. It is shown that for the particular application it does not increase the solution time to include the transit time constraints and that including the transit time is essential to offer customers a competitive product.
A generic point-absorbing wave energy converter is modeled in CFD as a vertical cylinder, moored with a single catenary chain that is fully coupled through a dynamic mooring code. The method of choice is very complete and takes much of the non-linearities in the highly coupled system of the moored body into account. The paper presents numerical results compared with experimental data for surge, heave and pitch motion in both decay tests and regular waves. Further, the wave motion response of the cylinder is computed using both a viscous and a non-viscous formulation as a first attempt to quantify viscous effects. Results show a good match between numerical and experimental results in heave, while the surge and pitch motion are more difficult to reproduce. The mooring load cycle appearance compares well with the experiments in shape but gives higher peak values. Although made at low Keulegan-Carpenter numbers, the simulations show vortical structures due to the heave motion, and the resulting motions are clearly affected by the inclusion or exclusion of viscosity. More test-cases and detailed experimental results are needed for further quantification of the viscous impact on floating point absorbers.
A number of solutions, with varying efficiency, have been proposed to mitigate discards. In this paper twelve mitigation measures were reviewed by their strengths and weaknesses, along with opportunities and threats, they might entail. How mitigation methods could either support or counteract others was also reviewed. The analyses of the mitigation measures are based on expert knowledge and experience and supported with existing literature. Discarding is highly variable and is influenced by numerous biological, technical and operational factors as well as social and economic drivers. These influences need to be carefully considered when designing management approaches. Finally, all reforms must be carefully considered within the context of a broader management system. The full management system needs to be thought of coherently to create an incentive framework that motivates fishers to avoid unwanted catches. It is only in this setting that discard mitigation methods may be potentially effective.
This article deals with the implementation of ecosystem-based marine management in the Baltic Sea. It explores and documents in particular the preliminary lessons from environmental and fisheries management with reference to the Helsinki Commission Group for implementation of the ecosystem approach and the Baltic Sea Fisheries Forum, both examples of regionalization processes in order to implement ecosystem-based marine management. The Helsinki Commission Group for implementation of the ecosystem approach is a joint management body for the implementation of the Baltic Sea Action Plan and the European Union's Marine Strategy Framework Directive. The Baltic Sea Fisheries Forum is a new governing body to facilitate regional cooperation in fisheries management. The aim of the article is twofold: a) to describe and discuss two different pathways of regionalization in the Baltic Sea and b) to explore how these forms of regionalization could contribute to the implementation of governance structures needed to implement ecosystem-based marine management at the level of a regional sea – efficiently, legitimately and effectively. We conclude that a nested governance structure could be developed by building upon existing institutions while learning from new initiatives to organize stakeholder involvement.
The current offshore oil & gas multi-phase production and transportation installations have big challenges related to the slugging flow: An unstable multi-phase flow regime where the flow rates, pressures and temperatures oscillate in the considered processes. Slug can be caused by different operating conditions and installation structures. The most severe slugs are often induced in long vertical risers or production wells, where liquid blocks gas at the riser/well base and correspondingly it causes the pressure to accumulate and hence originates the oscillating performance. There are many severe consequences to the production processes because of the slugging flow. This paper reviews some observed latest status and key challenges about slug detection, dynamical modeling and elimination of slugging flows. Mathematical modeling of slug has been used to investigate the slug mechanism and anti-slug control. Most of available models are based on mass-balance formulations, which often require sufficient data for reliable parameter tuning/identification. Slug elimination and control have been investigated for many years and there exist many solutions to eliminate the slug, but some of these methods can simultaneously reduce the oil & gas production, which is a very big concern as the production rate is the key evaluation parameter for offshore production. We conclude that the slugging flow is a well-defined phenomenon, even though this subject has been extensively investigated in the past decades, the cost-effective and optimal slug modeling and control are still open topics with many related challenges.
The costs of buying tonnage – whether new built or second hand – are so high that most Owners will need the assistance of Financers in order to be able to make the purchase. This raises several legal questions regarding ship’s finance. This article will provide a discussion of certain aspects of ships’ finance under Danish Law relevant to the charterparty trade.
The factual starting point for the paper is that a vessel is working in or intended to work in the charterparty trade, most particularly under long term time charterparties or Contracts of Affreightment. In such a situation, we find a tri-party relationship between the Financers, the Owners and the Charterers. When things are well, the interests of these three parties are on a par. The Charterers wish to use the vessel in order to make a profit, enabling them to pay the Owners. The Owners, receiving the hire or freight, are able to pay the crew, maintain the vessel and pay the Financers. However, the moment the financial stability of the Owner or the Charterer is threatened, the three parties will tend to have conflicting interests. The Financers, if unpaid, may wish to sell the vessel in order to cover at least some of their losses. The Charterers may wish to continue the use of the vessel, which may be inconsistent with a (forced) sale. Alternatively, the Charterers may wish to be freed of their obligations under the charterparty if the Owner enters into receivership or other types of insolvency proceedings. They may not be comfortable with e.g. having the Owners estate in bankruptcy running the vessel. And ultimately the Owners estate may wish to reconstruct the company in order to stay in business, for which end keeping the vessel as an asset and the income flowing from a (continued) charterparty may be a precondition.
The paper will discuss the problem with the starting point in Danish law on the subject, and investigate whether Danish law is apt to protect the conflicting interests of the three parties. However, the paper will make comparisons to other laws, mainly English law and Norwegian law. Also, the paper will discuss the general problems with the definitions of how a working vessel should generally be considered in the eyes of the law (is it simply any piece of chattels or is it more akin to a whole production facility?) and as well as whether the service provided by both owners and charterers under a charterparty should be considered personal or generic. Thus, although the paper uses Danish law as a starting point, it provides points of discussion of more general interest.
The paper ultimately concludes that Danish law does provide an adequate protection and balancing of the interest of the parties, but that uncertainties and the general inaccessibility of the law must be considered to restrict its use to the full – to the detriment of market interests.