We solve a central problem in the liner shipping industry called the liner shipping fleet repositioning problem (LSFRP). The LSFRP poses a large financial burden on liner shipping firms. During repositioning, vessels are moved between routes in a liner shipping network. Liner carriers wish to reposition vessels as cheaply as possible without disrupting cargo flows. The LSFRP is characterized by chains of interacting activities with a multicommodity flow over paths defined by the activities chosen. Despite its industrial importance, the LSFRP has received little attention in the literature. We introduce a novel mathematical model and a simulated annealing algorithm for the LSFRP with cargo flows that makes use of a carefully constructed graph; we evaluate these approaches using real-world data from our industrial collaborator. Additionally, we compare the performance of our approach against an actual repositioning scenario, one of many undertaken by our industrial collaborator in 2011. Our simulated annealing algorithm is able to increase the profit from $18.1 to $31.8 million using only a few minutes of CPU time. This shows that our algorithm could be used in a decision support system to solve the LSFRP.
This paper evaluates the influence of forecast horizon and observation fit on the robustness and performance of a specific freight rate forecast model used in the liner shipping industry. In the first stage of the research, a forecast model used to predict container freight rate development is presented by exploring the relationship between individual company’s rates and aggregated market rates, and thus assists in dealing with uncertainty and market volatility for a given business situation. In the second stage, a design of experiment approach is applied to highlight the influence of the forecast horizon and observation fit and their interactions on the forecast model’s performance. The results underline the complicated nature of creating a suitable forecast model by balancing business needs, a desire to fit a good model and achieve high accuracy. There is strong empirical evidence from this study; that a robust model is preferable, that overfitting is a true danger, and that a balance must be achieved between forecast horizon and the number of observations used to fit the model. In addition, methodological guidance has also been provided on how to test, design, and choose the superior model for business needs.
This article investigates recent reforms of the Greenland coastal fisheries in order to contribute to the general lessons on reform and policy networks in the context of a changing Arctic stakeholdership. It analyzes participation in fisheries governance decision-making by examining the emergence of discourses and policy networks that come to define the very need for reform. A policy network is identified across state ministries, powerful officials, banks and large scale industry that defined the need for fisheries reform within a 'grand reform' discourse. But inertia characterized the actual decision-making process as reform according to this 'grand reform' discourse was blocked by a combination of small-scale fishermen' informal networks and the power of the parliamentary majority. After a parliamentary shift in power the new government implemented the 'grand reform' gradually whilst new patterns of participation and exclusion emerged. In this process, the identities of the participating participants were reinterpreted to fit the new patterns of influence and participation. The article argues that fishery reform does not necessarily start with the collective recognition of a problem in marine resource use and a power-neutral process of institutional learning. Instead, it argues that fishery reform is likely to be the 'reform of somebody' and that this 'somebody' is itself a changing identity.
Slugging flow in the offshore oil & gas production attracts a lot of attention due to its limitation of production rate, periodic overload on processing facilities, and even direct cause of emergency shutdown. This work aims at two correlated objectives: (i) Preventing slugging flow; and meanwhile, (ii) maximizing the production rate at the riser of an offshore production platform, by manipulating a topside choke valve through a learning switching model-free PID controller. The results show good steady-state performance, although a long settling time due to the unknown reference for no slugging flow.
The legal limbo that defines the maritime space over which the process of delimitation of the outer continental shelf is applied appears today as an eminently practical question that needs to be addressed. The institutional framework provided by UNCLOS, which establishes the existence of an internationalized space on the seabed - the area - seems limited to respond to a debate that confuses Geology with Law. This article focuses on the powers of the International Seabed Authority as an agency authorized to act on behalf of Mankind by exploring its weaknesses in its exercise of this mandate in the context of that process. By analyzing the conflict between the expansionist goals of States and the embodied principle that gives the Authority the assignment to act on behalf of Mankind in securing a space that, according to the text of the Convention, belongs to it, we conclude that there are apparent inconsistencies in the institutional framework created the Montego Bay Convention. In our exegesis of Part XI of the Convention, we work on the cogent force of that principle and raise questions about the legal legitimacy of the entire process, ie in the absence of a clear statement by the above-mentioned Authority. We conclude that the text of the Convention provides the possibility of a direct intervention by the Authority but that there are still no political conditions for such a possibility to be realised.
This paper examines the costs and benefits of reduction measures for the shipping industry to comply with the forthcoming sulphur emission regulations. Sulphur scrubbers and marine gas oil are two promising alternatives for ship owners. However, their economic comparisons are primarily based on a private perspective. This paper provides a wider viewpoint by integrating the private abatement costs of ship owners and the social environmental benefits from emission reduction. The results showed that the price spread between marine gas oil and heavy fuel oil is a determining factor in making this choice. Marine gas oil tends to have higher net present values than scrubbers when the price spread of fuel is less than 231 Euros per tonne. Furthermore, it is more beneficial to install a scrubber on new ships than retrofits. An old ship is not suitable for a scrubber installation when its remaining lifespan is less than 4 years.
This article discusses the development of second ship registers and their interconnections to the policy idea of maritime clusters. Through a narrative of the contemporary history of Danish maritime policy, the article shows how these apparently different policy measures were closely related and together constitute a coherent framework based upon specific values, views of cause–effect relationships, and perceptions of major challenges and their context. Danish maritime policy provides an excellent case for the study of the contemporary history of maritime policy-making. Denmark was among the first of the traditional shipping nations to set up a second register, and the concept of maritime clusters became part of Danish maritime policy before it emerged as a construct in European Union maritime policy. We provide detail on the unfolding of some of the most important recent events in Danish maritime policy and highlight its development as a process of learning that involves the prolonged drafting and fine-tuning of statements and ideas, and the borrowing and adjustment of policy ideas developed elsewhere.
The purpose of this paper is to clarify some important issues as regards ship speed optimization at the operational level and develop models that optimize ship speed for a spectrum of routing scenarios in a single ship setting. The paper’s main contribution is the incorporation of those fundamental parameters and other considerations that weigh heavily in a ship owner’s or charterer’s speed decision and in his routing decision, wherever relevant. Various examples are given so as to illustrate the properties of the optimal solution and the various trade-offs that are involved.
Due to the harsh weather conditions, severe spatial limitations and extremely high safety requirements, the indoor climate control for offshore oil & gas production platforms is much more challenging than any on-shore situations. For instance, the indoor pressure of man-board quarters should be kept all the way above the ambient pressure according to safety regulations. Meanwhile, the indoor air needs to be regularly changed in order to guarantee the indoor air quality. Both requirements could be possibly achieved by automatically manipulating either the throttle valve located at the terminal of the inlet channel in the considered Heating Ventilation and Air-Condition (HVAC) system, or the pressurization system located inside the inlet channel, or both of them in a coordinated way. A Model-Predictive Control (MPC) solution to control the inlet throttle has been proposed in our previous work. This paper proposes a set of control solutions to regulate the variable speed pressurization fan system such that the energy efficiency of the considered HVAC system can be explicitly considered. A combined feed-forward with a PI-based feedback control solution, and an MPC solution are proposed based on derived simple system models. Some preliminary simulation results show that both control solutions can keep the indoor pressure and the air circulation in a very satisfactory and robust manner, even subject to the presence of severe disturbances.
Different port operating policies have the potential to reduce emissions from shipping; however, their efficacy varies for different ports. This article extends existing literature to present a consistent and transferable methodology that examines emissions reduction port policies based on ship-call data. Carbon dioxide (CO2); sulphur dioxide (SO2); nitrogen oxides (NOx); and black carbon (BC) emissions from near-port containership activities are estimated. Two emissions reduction policies are considered for typical container terminals. Participation of all calling vessels with a speed reduction scheme can lead to reductions of 8–20 per cent, 9–40 per cent and 9–17 per cent for CO2, SO2 and NOx, respectively. However, speed reduction policies may increase BC emissions by up to 10 per cent. Provision of Alternative Marine Power (AMP) for all berthing vessels can reduce in-port emissions by 48–70 per cent, 3–60 per cent, 40–60 per cent and 57–70 per cent for CO2, SO2, NOx and BC, respectively. The analysis shows that emissions depend on visiting fleet, berthing durations, baseline operating pattern of calling ships, sulphur reduction policies in force and the emissions intensity of electricity supply. The potential of emissions reduction policies varies considerably across ports making imperative the evaluation and prioritization of such policies based on the unique characteristics of each port and each vessel.