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Reliability-Oriented Control of Battery Energy Storage Systems

Tahir, Muhammad Usman (PI)Blaabjerg, Frede (Supervisor)Sangwongwanich, Ariya (Supervisor)Stroe, Daniel-Ioan (Supervisor)

The importance of reliable battery energy storage systems (BESS) is key to the sustainability of many applications such as renewable power, smart grids, and electric vehicles (EVs). Due to decreasing cost and maturing technology, the Li-ion batteries are now widely used for grid-level storage, grid support for improved power quality, integration with photovoltaic systems, and EV applications. A Li-ion battery pack typically comprises Li-ion cells connected in a suitable combination of series and parallel structure. A battery management system (BMS) is required for charging and discharging, monitoring the current and voltage of each cell or string, battery protection, and temperature control. The system's reliability depends on the BESS reliability and is affected by many factors, including temperature, C-rate, DOD. This research aims to improve BESS reliability by using accurate lifetime modelling for various BMS and converter topologies to identify real-time BESS health and ensure reliability through a suitable control strategy. In particular, the reliability of the BESS for centralized, modularised, distributed, and decentralized topology will be explored along with its cost-reliability trade-off. I will focus on control strategies for optimizing BESS reliability for different applications.

Not yet published / 2025
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The Role of Industry Self-regulation in International Maritime Law

Christian Frier, Kim Østergaard

This chapter examines the role of industry self-regulation in relation to international maritime law. While multilateral intergovernmental agreements are important to encouraging regulatory harmonisation, private actors have an essential role in industry, both in developing norms and in making rules and standards effective to ensure safe and secure shipping on clean oceans. Nonetheless, private actors are often overlooked and yet to be placed in the context of international maritime law and especially the United Nations Convention of Law of the Sea (UNCLOS). This chapter does so by analysing industry self-regulation in relation to UNCLOS, flag states and the International Maritime Organization (IMO) respectively.

Routledge / 2024
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Identifying Key Issues in Integration of Autonomous Ships in Container Ports: A Machine-Learning-Based Systematic Literature Review

Enna Hirata, Annette Skovsted Hansen

Background: Autonomous ships have the potential to increase operational efficiency and reduce carbon footprints through technology and innovation. However, there is no comprehensive literature review of all the different types of papers related to autonomous ships, especially with regard to their integration with ports. This paper takes a systematic review approach to extract and summarize the main topics related to autonomous ships in the fields of container shipping and port management. Methods: A machine learning method is used to extract the main topics from more than 2000 journal publications indexed in WoS and Scopus. Results: The research findings highlight key issues related to technology, cybersecurity, data governance, regulations, and legal frameworks, providing a different perspective compared to human manual reviews of papers. Conclusions: Our search results confirm several recommendations. First, from a technological perspective, it is advised to increase support for the research and development of autonomous underwater vehicles and unmanned aerial vehicles, establish safety standards, mandate testing of wave model evaluation systems, and promote international standardization. Second, from a cyber–physical systems perspective, efforts should be made to strengthen logistics and supply chains for autonomous ships, establish data governance protocols, enforce strict control over IoT device data, and strengthen cybersecurity measures. Third, from an environmental perspective, measures should be implemented to address the environmental impact of autonomous ships. This can be achieved by promoting international agreements from a global societal standpoint and clarifying the legal framework regarding liability in the event of accidents.

MDPI / 2024
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An efficient method for estimating the structural stiffness of flexible floating structures

Baoshun Zhou, Zhixun Yang, Mostafa Amini-Afshar, Yanlin Shao, Harry B. Bingham

In the hydroelastic analysis of large floating structures, the structural and hydrodynamic analyses are coupled, and the structural stiffness plays an important role in the accurate prediction of the response. However, there is usually a large difference between the longitudinal and the cross-sectional scales of modern ships, and the sectional configurations are generally complex, making it difficult to obtain the exact structural stiffness. Using a full finite element model to calculate the structural stiffness is inevitably time-consuming. Since modern ship structures are usually nearly periodic in the longitudinal direction, we treat the hull as a periodic Euler–Bernoulli beam and use a novel implementation of asymptotic homogenization (NIAH) to calculate the effective stiffness. This can greatly improve the computational efficiency compared with a full finite element model. Based on a combination of finite element and finite difference methods, we develop an efficient analysis technique to solve the hydroelastic problem for nearly-periodic floating structures. The finite element method is used to efficiently calculate the structural stiffness, and the finite difference method is used to solve the hydrodynamic problem. This proposed technique is validated through several test cases with both solid and thin-walled sections. A range of representative mid-ship sections for a container ship are then considered to investigate the influence of both transverse and longitudinal stiffeners on the structural deformations. A simple method for including non-periodic end effects is also suggested.

Marine Structures / 2024
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Shared State Responsibility for Land-Based Marine Plastic Pollution

Yoshifumi Tanaka

Plastic litter is introduced into the oceans from land-based sources located in many countries around the world. Marine plastic pollution may therefore be attributable to multiple states, resulting in shared state responsibility. This article discusses the issue of shared state responsibility for land-based marine plastic pollution by examining (i) primary rules of international law concerning the prevention of land-based marine plastic pollution; (ii) secondary rules of international law on this subject; and (iii) possible ways of strengthening the primary rules. It concludes that the barrier for the invocation of state responsibility may become higher in cases of shared state responsibility. Three cumulative solutions to this problem are proposed: elaborating the obligation of due diligence, strengthening compliance procedures, and interlinking regimes governing the marine environment and international watercourses.

Transnational Environmental Law / 2023
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The European Union’s quest to become a global maritime security provider

Christian Bueger, Timothy Edmunds

The European Union (EU) seeks to become a global maritime-security actor, yet strategic challenges influence its maritime-security strategy process. Is there a distinctive and coherent EU approach to global maritime security, and how should the EU address the growing range of maritime challenges, including the intensification of militarized competition in the Indo-Pacific?

Naval War College Review / 2023
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A comparative risk analysis on CyberShip system with STPA-Sec, STRIDE and CORAS

Rishikesh Sahay, D. A. Sepulveda Estay, Weizhi Meng*, Christian D. Jensen, Michael Bruhn Barfod

The widespread use of software-intensive cyber systems in critical infrastructures such as ships (CyberShips) has brought huge benefits, yet it has also opened new avenues for cyber attacks to potentially disrupt operations. Cyber risk assessment plays a vital role in identifying cyber threats and vulnerabilities that can be exploited to compromise cyber systems. Understanding the nature of cyber threats and their potential risks and impact is essential to improve the security and resilience of cyber systems, and to build systems that are secure by design and better prepared to detect and mitigate cyber attacks. A number of methodologies have been proposed to carry out these analyses. This paper evaluates and compares the application of three risk assessment methodologies: system theoretic process analysis (STPA-Sec), STRIDE and CORAS for identifying threats and vulnerabilities in a CyberShip system. We specifically selected these three methodologies because they identify threats not only at the component level, but also threats or hazards caused due to the interaction between components, resulting in sets of threats identified with each methodology and relevant differences. Moreover, STPA-Sec, which is a variant of the STPA, is widely used for safety and security analysis of cyber physical systems (CPS); CORAS offers a framework to perform cyber risk assessment in a top-down approach that aligns with STPA-Sec; and STRIDE (Spoofing, Tampering, Repudiation,Information disclosure, Denial of Service, Elevation of Privilege) considers threat at the component level as well as during the interaction that is similar to STPA-Sec. As a result of this analysis, this paper highlights the pros and cons of these methodologies, illustrates areas of special applicability, and suggests that their complementary use as threats identified through STRIDE can be used as an input to CORAS and STPA-Sec to make these methods more structured.

Computers and Security / 2023
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Closing the loop: Establishing reverse logistics for a circular economy, a systematic review

Pravin Kumar Mallick*, Kim Bang Salling, Daniela C.A. Pigosso, Tim C. McAloone

Reverse Logistics (RL) of end-of-use/end-of-life products has become a vital part of circular economy practices for manufacturers. However, significant quantities of resources are still landfilled instead of being recovered. With mounting pressure on businesses to address the sustainability crises (resources, climate change, waste, toxicity) on account of the take-make-dispose-based linear economy, companies today realise the importance of RL but face several barriers to implementing it, including a lack of knowledge. Although several studies have investigated different aspects of RL in various industries in different country settings, less attention has been devoted to developing a systematic and holistic approach for designing and implementing RL. To address these gaps, this paper reviews 116 scholarly articles published between 2011 and 2021 to identify attributes related to the design and implementation of RL systems. Based on a systematic literature review, a conceptual framework is presented covering the key activities, drivers and barriers, stakeholder engagement and performance management in RL. Such a framework can support companies evaluate different approaches and strategies, as well as the opportunities and challenges of designing and implementing RL and transitioning towards a Circular Economy.

Journal of Environmental Management / 2023
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Innovation Ecosystems in Ports: A Comparative Analysis of Rotterdam and Valencia

Jonas Mendes Constante*, Peter W. de Langen, Salvador Furió Pruñonosa

The term ‘innovation ecosystem’ has become popular among stakeholders involved in innovation. The core idea is that innovation does not thrive through isolated actions of individual companies, but rather depends on a broad array of interrelated actors, institutions and policies. In this paper, we apply the concept of innovation ecosystems to ports by first providing a theoretical overview of its components and then comparing the efforts to build such an ecosystem in the port cities of Rotterdam and Valencia. Our main findings are as follows. First, the importance of innovation for the ability of ports to continue to create ‘value for society’ is widely acknowledged. Second, research and development (R&D) activities in both Rotterdam and Valencia are relatively limited and the dominant innovation challenge is the early application of new technologies developed outside the ports industry. Third, a ‘systemic approach’ is required to understand the innovation ecosystem in ports, given the strong interrelations among companies in the port and the need for broad coalitions to implement new technologies. Fourth and fifth, human capital formation and research cooperation, respectively, play a central role in improving the port innovation ecosystem. Finally, the ecosystem in Rotterdam is ‘distributed and connected’ while Valencia is more centralised.

Journal of Shipping and Trade / 2023
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Investigation of Combustion Characteristics, Physical and Chemical Ignition Delay of Methanol Fuel in a Heavy-duty Turbo-charged Compression Ignition Engine

Chong Cheng*, Rasmus Faurskov Cordtz, Troels Dyhr Pedersen, Kim Winther, Niels Langballe Førby, Jesper Schramm

In previous research, there have been more investigations on methanol blended with other fuels such as diesel, biodiesel, gasoline, etc., but fewer investigations on methanol with ignition additives as a mono-fuel. To better understand the methanol mono-fuel combustion characteristics and to further apply them, a combined experimental and simulation study of methanol in a Scania heavy-duty compression ignition (CI) engine was carried out in this work. The experiments consisted of four groups with variable injection timings, variable fraction of ignition additives, variable charge air temperatures, and variable overall excess air ratios/power sweeps. Heat release rate (HRR), cylinder pressure, ignition delay and indicated efficiency were analyzed for each case. The analysis showed that the combustion type was partially premixed combustion (PPC) in some cases and diesel-like combustion in the rest. By observing all cases, the shortest ignition delay was 14.1°, and the longest was 22.8°. The indicated efficiencies were in the range of 0.35 to 0.43. Simulations and validation analyses were performed for all cases by a multi-packets model. The physical and chemical ignition delays were predicted. The physical ignition delays were in the range of 4.25 to 8.10°, and the chemical ignition delays were in the range of 6.66 to 17.1°. The chemical ignition delay was always longer than the physical one. This indicates that chemical ignition delay has to be prioritized to improve the ignition performance of methanol fuel.

Fuel / 2023
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