The International Energy Agency Technology Collaboration Program for Ocean Energy Systems (OES) initiated the OES Wave Energy Conversion Modeling Task, which focused on the verification and validation of numerical models for simulating wave energy converters (WECs). The long-term goal is to assess the accuracy of and establish confidence in the use of numerical models used in design as well as power performance assessment of WECs. To establish this confidence, the authors used different existing computational modeling tools to simulate given tasks to identify uncertainties related to simulation methodologies: (i) linear potential flow methods; (ii) weakly nonlinear Froude–Krylov methods; and (iii) fully nonlinear methods (fully nonlinear potential flow and Navier–Stokes models). This article summarizes the code-to-code task and code-to-experiment task that have been performed so far in this project, with a focus on investigating the impact of different levels of nonlinearities in the numerical models. Two different WECs were studied and simulated. The first was a heaving semi-submerged sphere, where free-decay tests and both regular and irregular wave cases were investigated in a code-to-code comparison. The second case was a heaving float corresponding to a physical model tested in a wave tank. We considered radiation, diffraction, and regular wave cases and compared quantities, such as the WEC motion, power output and hydrodynamic loading.
Strict limits on the maximum sulphur content in fuel used by ships have recently been imposed in some Emission Control Areas (ECAs). In order to comply with these regulations many ship operators will switch to more expensive low-sulphur fuel when sailing inside ECAs. Since they are concerned about minimizing their costs, it is likely that speed and routing decisions will change because of this. In this paper, we develop an optimization model to be applied by ship operators for determining sailing paths and speeds that minimize operating costs for a ship along a given sequence of ports. We perform a computational study on a number of realistic shipping routes in order to evaluate possible impacts on sailing paths and speeds, and hence fuel consumption and costs, from the ECA regulations. Moreover, the aim is to examine the implications for the society with regards to environmental effects. Comparisons of cases show that a likely effect of the regulations is that ship operators will often choose to sail longer distances to avoid sailing time within ECAs. Another effect is that they will sail at lower speeds within and higher speeds outside the ECAs in order to use less of the more expensive fuel. On some shipping routes, this might give a considerable increase in the total amount of fuel consumed and the CO2 emissions.
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.
In this article, we develop a deep neural network model to estimate the wave added resistance. The required data to train the model is generated using strip theory calculations over a wide range of hull geometries and operational conditions. The model is efficient as it only requires the ship’s main particulars: length, beam, draft, block coefficient, and slenderness ratio. In addition, we present an application of this model in a vessel performance framework. This will be used for predicting propulsion power and analyzing the degree of biofouling on ships from the company Ultrabulk2. The study shows that the developed deep neural network model produces reliable results in predicting the added wave resistance coefficient in comparison to strip theory calculations. Also, the developed ship propulsion and biofouling analysis display satisfactory output for monitoring hull performance under actual ship operational conditions.
Seafarers sail the high seas around the globe. In case of illness, they are protected by international regulations stating that the employers must pay all expenses in relation to repatriation, but very little is known about the cost of these repatriations. The objective of this study was to estimate the financial burden of repatriations in case of illness. We applied a local approach, a micro-costing method, with an employer perspective using four case vignettes: I) Acute myocardial infarction (AMI), II) Malignant hypertension, III) Appendicitis and IV) Malaria. Direct cost data were derived from the Danish Maritime Authority while for indirect costs estimations were applied using the friction cost approach. The average total costs of repatriation varied for the four case vignettes; AMI (98,823 EUR), Malignant hypertension (47,597 EUR), Appendicitis (58,639 EUR) and Malaria (23,792 EUR) mainly due to large variations in the average direct costs which ranged between 9560 euro in the malaria case and 77,255 in the AMI case. Repatriating an ill seafarer is a costly operation and employers have a financial interest in promoting the health of seafarers by introducing or further strengthen cost-effective prevention programs and hereby reducing the number of repatriations.
With the rise of ‘new’ state capitalisms, control over transport infrastructure has returned to the forefront of competition in the global economy. This article investigates how different state capitalisms interact to enable economic developments in ports. It tracks the relationship between state-owned firms in the shipping and ports sectors through a case study of the port of Valencia in Spain and COSCO shipping group. The article identifies state capitalisms as variegated and relational to analyze the ways in which qualitatively different state capitalist dynamics interact at different scales. The article identifies two state capitalist dynamics which have been dominant in determining relations between Spanish and Chinese state capitalisms: 1) A commercial dynamic of maximizing Spanish ports profits by establishing new relationships with Chinese firms; and 2) an expansionary dynamic of increasing market share of Chinese state-owned firms in European shipping markets. These two dynamics are synergistic and have contributed to the competitiveness of Spanish ports and Chinese shipping firms by providing new capital to the port of Valencia and expanding the port's profile as a hub in the eastern Mediterranean, while also further solidifying COSCO's position in European shipping markets and its internalization and vertical integration strateg
Under complex sea conditions, the energy demand for each device of renewable-energy ships presents a random situation, which makes the complex energy demand of the ship integrated energy system (SIES) uncertain during ship navigation. To ensure the economical, stable, and efficient operation of the SIES, this paper proposes a distributed stochastic energy management method to solve the energy management problem (EMP). Firstly, a framework for the SIES including both renewable energy and traditional energy is constructed. Based on the energy efficiency operation index (EEOI) and the operation mode of energy supply devices during navigation, the EMP of the SIES is raised. Then, considering the distributed structure and limited computing resources of the SIES, a distributed stochastic energy management method is proposed. Through this method, the disturbances of load demand can be effectively suppressed, and a stable energy supply is provided for devices such as power propellers. Furthermore, it is analyzed that the proposed method can converge to the O(η) (η is the fixed step size of the proposed method) neighborhood of the optimal energy management decision in the mean-square-error sense. Finally, the simulation results verify that the mean-square-error-optimal energy management decision of the SIES can be obtained by the proposed method in different scenarios, and the proposed method can solve the EMP of SIES under complex sea conditions.
Design
Our data set, collected via surveys from top managers and project managers involved in 86 NPD projects in 85 firms, is analyzed using PLS structural equation modeling.
Purpose
This study examines how technical drivers as well as social drivers influence organic communication and top management involvement (TMI) in new product development (NPD) projects. Technical drivers are strategic importance and product innovativeness and social drivers are intrinsic and extrinsic relevance. Organic communication is defined as continuous, bi-directional, and informal communication between top management and the NPD teams. Further, arguing that TMI must be studied as multi-faceted construct, TMI is conceptualized to occur as guidance, active motivation, providing resources, and creating a tolerant climate. Subsequently, the effect of TMI and organic communication on NPD performance is investigated.
Findings
We show that the strategic importance of the project has a positive influence on TMI through active motivation, providing resources, and creating a tolerant climate for innovation, but does not have an effect on guidance. Results also show that active motivation and organic communication improve budget and schedule adherence, whereas providing guidance and stimulating a tolerant climate have detrimental effects. In summary, our results show that only active motivation enhances all types of performance while stimulating a tolerant climate appears to have the opposite effect. The results revealed that organic communication between top management and the NPD team has a strong positive effect on all elements of TMI (providing guidance, actively motivating the NPD team, providing resources, and creating a tolerant climate). In other words, when top management communicates with the NPD team throughout the project in an informal way and listens to the team in addition to engaging in a one-way communication, they are more likely to be seen by the team as being deeply involved in the project.
This study examines how the work of the International Law Commission (ILC) has contributed to the ‘progressive development’ of general international law relevant to regulating rescue and disembarkation of refugees and migrants found at sea. It explores the ILC’s texts on interpretation and implementation of international obligations, state responsibility, fragmentation and harmonization of international law, and the status of certain principles of general international law, including jus cogens general principles of law and the principle of good faith, which present legal parameters for regulation of maritime search and rescue operations. In conducting doctrinal examinations of international law and gathering evidence of the practice of States and other relevant actors, the ILC contributes by analysing, clarifying, and systemising important topics of general international law. However, state implementation frequently falls short of the legal interpretations of the ILC, particularly as they relate to respect for and protection of human rights at sea. Therefore, while the ILC needs new strategies to directly connect with States and international organisations, it remains reliant on the mutual following of national and international courts and tribunals, and its mutual contribution in scholarship.
Irregular migration by sea leads states such as Italy and Australia to conduct maritime rescue operations involving refugees and other migrants. During these operations, states must deal with the question of where to disembark survivors. The law of the sea regime obliges states to ensure survivors are delivered to a 'place of safety', arguably requiring maritime officers to merely consider the physical safety of survivors immediately on disembarkation. Non-binding International Maritime Organization guidelines state that the need to avoid disembarking refugees and asylum-seekers in the states of departure or origin is also a consideration. The guidelines refer to other 'relevant' international law, including treaties dealing with 'refugee refoulement' or refoulement in connection with a risk of torture. Under the international human rights law regime, including international refugee law, states' obligations in relation to non-refoulement are broader and prohibit the return of refugees and migrants to states where they directly or indirectly face persecution, torture or other serious harm. In interpreting 'place of safety', this work argues that there is insufficient consensus to integrate the two legal regimes. Nevertheless, states can be under co-existing human rights obligations that place limits on the disembarkation of rescued refugees and migrants.