Media: Paper


The time constrained multi-commodity network flow problem and its application to liner shipping network design

Karsten, Christian Vad; Pisinger, David; Ropke, Stefan; Brouer, Berit Dangaard

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.

Transportation Research Part E: Logistics and Transportation Review Volume 76 / 2015
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Danish Rules on Securities and other protective rights in the chartparty trade: an appraisal

Siig, Kristina

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.

MarIus / 2015
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Uncertainty in Fleet Renewal: A Case from Maritime Transportation

Pantuso, Giovanni; Fagerholt, Kjetil; Wallace, Stein W.

This paper addresses the fleet renewal problem and particularly the treatment of uncertainty in the maritime case. A stochastic programming model for the maritime fleet renewal problem is presented. The main contribution is that of assessing whether or not better decisions can be achieved by using stochastic programming rather than employing a deterministic model and using average data. Elements increasing the relevance of uncertainty are also investigated. Tests performed on the case of Wallenius Wilhelmsen Logistics, a major liner shipping company, show that solutions to the model we present perform noticeably better than solutions obtained using average values.

Transportation Science, 50 (2) / 2015
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Collisions damage assessment of ships and jack-up rigs

Zhang, Shengming; Pedersen, Preben Terndrup; Ocakli, Hasan

Ship collision with offshore installations is one of the key concerns in design and assess of platforms performance and safety. This paper presents an analysis on collision energy and structural damage in ship and offshore platform collisions for various collision scenarios. The platform or rig is treated as either rigid or flexible and its sensitivity on collision energy and structural damage is studied. An application example where an ice-strengthened supply vessel collides against a jack-up rig is analysed and the crushing resistance of the involved thin-walled structures is evaluated.

Ships and Offshore Structures, Volume 10 / 2015
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What is maritime security?

Bueger, Christian

Maritime security is one of the latest buzzwords of international relations. Major actors have started to include maritime security in their mandate or reframed their work in such terms. Maritime security is a term that draws attention to new challenges and rallies support for tackling these. Yet, no international consensus over the definition of maritime security has emerged. Buzzwords allow for the international coordination of actions, in the absence of consensus. These, however, also face the constant risk that disagreements and political conflict are camouflaged. Since there are little prospects of defining maritime security once and for all, frameworks by which one can identify commonalities and disagreements are needed. This article proposes three of such frameworks. Maritime security can first be understood in a matrix of its relation to other concepts, such as marine safety, seapower, blue economy and resilience. Second, the securitization framework allows to study how maritime threats are made and which divergent political claims these entail in order to uncover political interests and divergent ideologies. Third, security practice theory enables the study of what actors actually do when they claim to enhance maritime security. Together these frameworks allow for the mapping of maritime security.

Marine Policy, Volume 53 / 2015
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Study on Short-term Variability of Ship Responses in Waves

Nielsen, Ulrik Dam; Iseki, Toshio

Short-term variability of ship responses is investigated by cross-spectrum analysis. In a steady state condition, it is well known that a certain length of sampled data is required for stable results of the spectral analysis. However, the phase lag between responses, in terms of the phase angle of the cross-spectra, has not been discussed in detail. Using long stationary time series, the transition of amplitudes and relative phase angles of the cross-spectra has
been investigated by iterative analyzes with a few seconds of time shifting. In the results, the short-term variability of the relative phase angle was observed. In effect, the variability may compromise the accuracy of the wave buoy analogy.

Nihon Kokai Gakkai Ronbunshu / The Journal of Japan Institute of Navigation, 132 / 2015
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On two speed optimization problems for ships that sail in and out of emission control areas

Fagerholt, Kjetil; Psaraftis, Harilaos N.

This paper deals with two speed optimization problems for ships that sail in and out of Emission Control Areas (ECAs) with strict limits on sulfur emissions. For ships crossing in and out of ECAs, such as deep-sea vessels, one of the common options for complying with these limits is to burn heavy fuel oil (HFO) outside the ECA and switch to low-sulfur fuel such as marine gas oil (MGO) inside the ECA. As the prices of these two fuels are generally very different, so may be the speeds that the ship will sail at outside and inside the ECA. The first optimization problem examined by the paper considers an extension of the model of Ronen (1982) in which ship speeds both inside and outside the ECA are optimized. The second problem is called the ECA refraction problem, due to its conceptual similarity with the refraction problem when light travels across two different media, and also involves optimizing the point at which the ship crosses the ECA boundary. In both cases the objective of the problem is to maximize daily profit. In addition to mathematical formulations, examples and sensitivity analyses are presented for both problems.

Transportation Research Part D: Transport and Environment, Volume 39 / 2015
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A survey on maritime fleet size and mix problems

Pantuso, Giovanni; Fagerholt, Kjetil; Hvattum, Lars Magnus

This paper presents a literature survey on the fleet size and mix problem in maritime transportation. Fluctuations in the shipping market and frequent mismatches between fleet capacities and demands highlight the relevance of the problem and call for more accurate decision support. After analyzing the available scientific literature on the problem and its variants and extensions, we summarize the state of the art and highlight the main contributions of past research. Furthermore, by identifying important real life aspects of the problem which past research has failed to capture, we uncover the main areas where more research will be needed.

European Journal of Operational Research, Volume 235, Issue 2 / 2014
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A branch-and-price algorithm to solve the integrated berth allocation and yard assignment problem in bulk ports

Robenek, Tomáš; Umang, Nitish; Bierlaire, Michel; Ropke, Stefan

In this research, two crucial optimization problems of berth allocation and yard assignment in the context of bulk ports are studied. We discuss how these problems are interrelated and can be combined and solved as a single large scale optimization problem. More importantly we highlight the differences in operations between bulk ports and container terminals which highlights the need to devise specific solutions for bulk ports. The objective is to minimize the total service time of vessels berthing at the port. We propose an exact solution algorithm based on a branch and price framework to solve the integrated problem. In the proposed model, the master problem is formulated as a set-partitioning problem, and subproblems to identify columns with negative reduced costs are solved using mixed integer programming. To obtain sub-optimal solutions quickly, a metaheuristic approach based on critical-shaking neighborhood search is presented. The proposed algorithms are tested and validated through numerical experiments based on instances inspired from real bulk port data. The results indicate that the algorithms can be successfully used to solve instances containing up to 40 vessels within reasonable computational time.

European Journal of Operational Research, Volume 235 / 2014
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Emission inventories for ships in the arctic based on satellite sampled AIS data

Winther, Morten; Christensen, Jesper H.; Plejdrup, Marlene S.; Ravn, Erik S.; Eriksson, Ómar F.; Kristensen, Hans Otto

This paper presents a detailed BC, NOx and SO2 emission inventory for ships in the Arctic in 2012 based on satellite AIS data, ship engine power functions and technology stratified emission factors. Emission projections are presented for the years 2020, 2030 and 2050. Furthermore, the BC, SO2 and O3 concentrations and the deposition of BC are calculated for 2012 and for two arctic shipping scenarios – with or without arctic diversion routes due to a possible polar sea ice extent in the future.

In 2012, the largest shares of Arctic ships emissions are calculated for fishing ships (45% for BC, 38% for NOx, 23% for SO2) followed by passenger ships (20%, 17%, 25%), tankers (9%, 13%, 15%), general cargo (8%, 11%, 12%) and container ships (5%, 7%, 8%). In 2050, without arctic diversion routes, the total emissions of BC, NOx and SO2 are expected to change by +16%, −32% and −63%, respectively, compared to 2012. The results for fishing ships are the least certain, caused by a less precise engine power – sailing speed relation.

The calculated BC, SO2, and O3 surface concentrations and BC deposition contributions from ships are low as a mean for the whole Arctic in 2012, but locally BC additional contributions reach up to 20% around Iceland, and high additional contributions (100–300%) are calculated in some sea areas for SO2. In 2050, the arctic diversion routes highly influence the calculated surface concentrations and the deposition of BC in the Arctic. During summertime navigation contributions become very visible for BC (>80%) and SO2 (>1000%) along the arctic diversion routes, while the O3 (>10%) and BC deposition (>5%) additional contributions, respectively, get highest over the ocean east of Greenland and in the High Arctic.

The geospatial ship type specific emission results presented in this paper have increased the accuracy of the emission inventories for ships in the Arctic. The methodology can be used to estimate shipping emissions in other regions of the world, and hence may serve as an input for other researchers and policy makers working in this field.

Atmospheric Environment Volume 91, July 2014 / 2014
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