Underwater radiated noise (URN) from ship propellers has attracted increasing interest in recent years due to its adverse environmental effects on marine life and their communication channels. The environmental concern to reduce shipping noise and the industrial requirements for faster computational tools are driving factors that promote research in the specialized domain of hydroacoustics. This thesis deals with the development of such a computationally efficient numerical tool, which can be used in the prediction of underwater radiated noise in the early design phase of propellers.
The numerical model is developed with two major objectives – versatility in assessing the relative contributions from the major propeller-noise generating mechanisms, and rapidity in prediction of overall noise behaviour. It uses the Farassat-1A solid-FWH formulation of the Ffowcs-Williams- Hawkings equation by defining equivalent acoustic sources on the propeller blade, sheet cavity and tip vortex cavity surfaces. In particular, the application of the solid-FWH formulation to the tip vortex cavity model is the major novelty in this thesis.
The hydrodynamic flow solution is obtained from a potential flow based solver ESPPRO, which includes analytical models of sheet cavitation and tip vortex cavitation. The hydroacoustic numerical model developed within this thesis, DoLPHiN, is a Python-based code that is primarily designed to accept input from ESPPRO; but during the research, the code has also been adapted to read input from the commercial, finite-volume-based Navier-Stokes solver, STAR-CCM+.
The numerical model implementations are verified through analytical case studies for simple geometrical shapes, such as a pulsating sphere and an oscillating cylindrical cavity. The verification study is further extended for propeller geometries by identifying approximate reference solutions in simplified operating conditions. The numerical tool is validated for industrial application through comparison of its noise prediction with model-scale and full-scale noise measurements. Specific characteristics of the propeller noise spectrum are identified in order to evaluate its noise prediction capabilities. The uncertainty factors involved when validating with experimental measurements are also explored in detail. Furthermore, a design study is presented, which shows potential use of the numerical tool in practical propeller design and optimization applications.
Global climate change, which is largely attributed to human activity, is one of the foremost challenges of the 21st century. In recent times, there have been notable alterations in the Earth's climate, resulting in profound impacts on ecosystems and biodiversity. These alterations are caused by greenhouse gas, such as carbon dioxide, methane, and nitrous oxide. Greenhouse gas emissions are caused by practices such as deforestation, industrial operations, and the combustion of fossil fuels in vehicles, vessels, aircraft, and manufacturing facilities. The maritime and aviation industry is currently responsible for approximately 6% of global greenhouse gas emissions. Due to logistical and economic constraints, these industries are heavily reliant on liquid fuels, making direct electrification options unavailable for large parts of these sectors. As a result, these sectors are considered ‘hard to abate’. Understanding the future climate mitigation challenges associated with the maritime and aviation sectors is crucial in shaping effective policy measures, avoiding stranded assets, and preserving the chance to meet Paris Agreement-compatible emission reduction pathways.
This thesis identifies three main challenges and proposes modelling approaches to address them when modelling decarbonization pathways for the aviation and maritime sectors. From these challenges, research gaps have been identified that this PhD thesis aims to fill. Three models have been developed for the thesis: a maritime optimization model, a maritime demand model, and an aviation demand model. The modelling landscape and methodology vary across models, ranging from econometrics and data science to mathematical optimization.
To overcome the challenges and fill in the research gaps, three corresponding modelling approaches have been successfully applied:
1. Developing a holistic decarbonization modelling landscape. This includes life-cycle representations of technology costs and emissions, the upscaling of bottleneck technologies, the availability of sustainable biomass, and consideration of competing demand from other industries, as well as representations of policy levers such as carbon pricing or improvements to fuel efficiency.
2. Developing demand models that interpret the underlying scenario narrative consistently (SSP framework).
3. Improving the representation of technological learning for low-carbon technologies in energy system models.
The findings acquired by applying these three modelling approaches are valuable for energy modellers, climate scientists, and policymakers and offer unique insights into the inherent system dynamics associated with decarbonization of hard-to-abate sectors. Utilizing this modelling landscape reveals that current decarbonization efforts for hard-to-abate sectors are insufficient.
Maritime transportation is an essential pillar of modern societies, serving as the backbone of global trade. The shipping industry relies heavily on fossil fuels, significantly impacting the environment and contributing to climate change. The International Maritime Organization (IMO) has introduced a strategy to reduce greenhouse gas emissions from international shipping and decarbonize the industry to combat this issue. This strategy aims to accomplish energy efficiency gains, transition to alternative fuels, and implement market-based measures.
Various energy efficiency indicators are in use to monitor the performance of ships, both from technical and operational perspectives. Building upon previous research that identified shortcomings in these indicators, this thesis investigates alternative methods of assessing the energy efficiency of ships. Emphasizing the importance of a benchmarking tool, the primary objective of this thesis is to contribute to the policy debate on reducing emissions in international shipping by developing a comprehensive carbon intensity indicator.
The thesis comprises four articles addressing various approaches to monitoring ship carbon emissions. The first article focuses on the influence of weather conditions on a ship’s energy efficiency, thereby contributing to the ongoing discussion on weather correction factors. Using model-based machine learning techniques, this article illustrates the diverse sea conditions encountered, their impact on energy efficiency, and the necessity of accounting for this diversity through multiple correction factors.
The second and third articles introduce and develop the concept of operational cycles for maritime transportation, drawing inspiration from the driving cycles employed in the automotive industry. The second article describes the process of generating operational cycles for the maritime sector as a novel concept. It validates this concept using real-world data obtained from a fleet of container ships. Building upon this foundation, the third article extends the concept by elaborating more comprehensive cycles that better represent real-world indicators.
The fourth article explores voluntary reporting frameworks in the shipping industry. It focuses on the Clean Cargo case and investigates the needs and interests of its members regarding this private initiative and related reporting framework. The discussion revolves around the role of these voluntary frameworks as complementary approaches to regulatory frameworks towards maritime decarbonization.
Based on the methodology developments and analysis through the thesis, the following key findings and recommendations are presented:
• The weather impact on ships’ fuel consumption prevents an accurate and real assessment of ships’ efficiency. Multiple weather correction factors for energy efficiency indicators introduce a novel approach.
• Inspired by the automotive industry, maritime operational cycles improve the assessment of technical and operational aspects of a ship’s energy efficiency. The cycles reduce the variability inherent to energy
efficiency indicators and are suitable as benchmarking tools.
• Although the IMO regulatory framework remains at the core of the maritime decarbonization strategy, regional regulatory frameworks and private initiatives have demonstrated their capacity to enhance industry
practices and facilitate regulatory developments.
This thesis contributes to enhancing carbon emissions monitoring in the maritime industry by introducing new methodologies and assessments. The resulting proposals are designed to enrich ongoing discussions within the IMO and complement the existing regulatory frameworks.
Containerfartens historiske udvikling bliver i litteraturen beskrevet som en revolution og en transformation af den internationale shippingbranche. De teknologiske og organisatoriske forandringer af livet til søs som fulgte med containerfarten har tilsvarende medført en forandring af maritime kulturer og en udfordring af de søfarendes identiteter.
Denne afhandling handler om danske containersøfolks erindringer, fortidsbrug og identitetskonstruktioner og undersøger, hvordan søfolkene fortæller sig selv i relation til deres levede erfaringer i containerfarten. Jeg analyserer i afhandlingen søfolkenes retrospektive fortidsfortolkninger som en måde at nærme mig en forståelse af de forandrede sømandsidentiteter.
Analytisk anlægger afhandlingen et subjektperspektiv, som anser fortiden for nærværende og åben i de mundtlige fortællingers fortolkninger og meningsforhandlinger af fortidens erfaringer. Jeg anskuer den narrative konstruktion af den personlige, autobiografiske, historie som identitetsdannende fortidsbrug, der udtrykker fortællerens subjektivitet. Med en erindringshistorisk tilgang til søfolkenes mundtlige fortællinger undersøger jeg, hvordan vi mennesker forstår os selv gennem de historier, vi fortæller om os selv.
Afhandlingen bygger empirisk på en række dybdegående oral history interviews med danske søfolk, der alle har erfaring inden for den internationale containerfart.
I afhandlingens analyser, viser jeg, hvordan søfolkene retfærdiggør og legitimerer deres valg om i første omgang at blive søfolk og senere at arbejde ombord på containerskibe. Jeg viser, hvordan søfolkene narrativt forhandler forskellige former for erfaret meningstab og aktivt tilskriver arbejdet og fællesskabet ombord på skibene en ny og brugbar mening. Jeg viser samtidig, hvordan den personlige historie konstrueres i dialog med kulturelt dominerende forestillinger og fortællinger. Sådanne forestillinger og fortællinger tilbyder den enkelte fortæller et tilgængeligt sprog at udtrykke sine personlige erfaringer i, men kan også virke begrænsende, hvis fortællerens erfaringer og forståelser ikke passer ind i de dominerende billeder. I sådanne tilfælde kan der opstå, hvad afhandlingen kalder en form for narrativt ubehag (discomposure), der kommer til udtryk som frustration og brud i fortællingens narrative sammenhæng.
Som en gennemgående metodisk pointe viser afhandlingen, hvordan interviewets intersubjektivitet er med til at forme den historie, som fortælles. Det personlige møde mellem fortæller og historiker og interviewets kulturelle kontekster indvirker på forskellig vis på den konstruerede historie. Fremfor at hævde en neutral og objektiv interviewsituation, tager afhandlingen i stedet konsekvensen af denne intersubjektivitet og skriver det konkrete møde mellem søfolkene som fortællere og mig som interviewer ind som en integreret del af den historiske fremstilling. Dette er både et narrativt greb og et metodisk valg, der skal sikre transparens ved at give læseren indblik i, hvordan historierne og mine tolkninger er blevet til.
Afhandlingen yder med sin tilgang og sine analyser flere bidrag til den eksisterende litteratur. Gennem de personlige fortællinger får vi større indsigt i søfolkenes levede liv og deres erfaringer med containerfartens historiske udvikling. Afhandlingen giver et menneskeligt perspektiv på historien om den internationale containerfart, der bidrager til vores viden om udviklingens identitetsmæssige betydning for de mænd og kvinder, som gennemlevede de historiske forandringer ude ombord på skibene.
Afhandlingen er en virksomhedshistorie, der tager oral history alvorligt både som forskningsfelt, metode og genre. Afhandlingen bidrager med sin erindringshistoriske tilgang til oral history til den fornyede samtale mellem forskningsfelterne oral history og virksomhedshistorie. Afhandlingen bringer metodiske og teoretiske indsigter fra den erindringshistoriske tradition ind i virksomhedshistorie og viser gennem sin egen narrative stil potentialet i en historieformidling, der sætter subjektivitet og erindring i centrum af sin analyse. Dermed bidrager afhandlingen også til den narrative vending inden for virksomhedshistorie ved ikke kun at anlægge et narrativt blik på de danske søfolks fortællinger men ved også at tage sig selv alvorligt som narrativ konstruktion.
This PhD thesis presents a numerical solution of the hydroelastic problems encountered especially by large flexible ships sailing in waves. The solution is implemented by extending an existing seakeeping tool (OceanWave3D-seakeeping) to allow for the efficient and accurate evaluation of the hydroelastic response of ships. OceanWave3D-seakeeping has been developed by the Maritime Group at DTU-Construct based on solving the linearized potential flow theory using high-order finite differences on overlapping curvilinear boundary-fitted grids. Modal superposition is employed to couple the hydrodynamic and structural analysis of ships at both zero and non-zero forward speed. The ship girder is approximated by an Euler-Bernoulli or a Timoshenko beam, and the vertical bending deformation is mainly considered in this work. The shear effects on the hydroelastic response are also investigated in the Timoshenko beam approximation. The solution has been validated against experimental measurements and reference numerical solutions for several test cases. The correct computation of the hydrostatic stiffness, structural stiffness and hydrodynamic forces is the key to the
accurate prediction of the hydroelastic response, and these three terms are discussed deeply in this thesis.
With respect to the hydrostatic stiffness model, some controversy has long existed in the literature about its correct form for elastic motion modes, with Newman [1] and Malenica [2] arriving at different forms which are respectively defined in earthand body-fixed reference systems. In this thesis a complete derivation of both forms including the buoyancy and gravitational terms is provided, and the equivalence of the two models associated with elastic motions is confirmed.
A finite element method (FEM) is a common way to compute the structural stiffness of ship hulls. However, for large modern ships, a FEM calculation based on a full structure is inevitably time-consuming since distinguished differences between the longitudinal and the cross-sectional scales of ship hulls usually exist, and the sectional configurations are generally complex, bringing difficulties to numerical modeling. Considering that the structure of modern ships (for example container ships), is usually nearly periodic in the longitudinal direction, in this thesis the ship hull is approximated as a periodic beam and a new implementation of asymptotic homogenization (NIAH) is introduced to efficiently calculate the structural stiffness. This can greatly improve the computational efficiency compared with a full FEM model. Several test cases with both solid and thin-walled sections are given to validate the proposed technique. A range of representative mid-ship sections for a container ship are also considered to investigate the influence of stiffeners on the hydroelastic response.
In the hydrodynamic part, zero-speed and forward-speed radiation and diffraction problems including the well-known m−terms in the body boundary conditions, have both been solved. For generalized modes, the boundary conditions using the corresponding generalized m−terms are applied in the calculation. Neumann-Kelvin (NK) and double-body (DB) linearization models are applied as the steady base flow, and their performance is investigated by comparison with experimental measurements. In head seas, the influence of increasing forward speed on the resonant response of the flexible modes is also studied.
Through the integration of hydroelastic analysis using potential flow theory, and advanced numerical techniques, this thesis contributes to a deeper understanding of the complex interaction between flexible ship hulls and ocean waves, offering valuable insights for the maritime industry.
The emissions of the maritime sector caused by ship transportation and other fossil fuel sources pose a threat to the environment and human health. It drives an increasing interest in adopting electrification solutions to revolutionize the conventional maritime energy-intensive and highly polluting industry. Accordingly, this thesis is one of the pioneering attempts to implement a seaport microgrid and carbon capture shore power system of cold ironing at a port dedicated to sustainability while remaining competitive.
However, the technological and research gaps of the conventional port scheduling paradigm constitute challenges in a synergy between the two prominent maritime electrification systems of seaport microgrids and cold ironing. The incorporation of cold ironing into seaport operations introduces new challenges to handling workflow and the potential impact of such integration has not yet been quantitatively addressed. Developing strategic management to improve port performance is always an issue for the port operators. This research gap motivated this study to develop an integrated operation and energy management framework by executing forecasting and optimization techniques for coordinating these technologies toward the emission neutrality goal.
This thesis begins with an extensive review of the significant aspects of cold ironing technology and seaport microgrids. A range of factors associated with the varying demand for cold ironing in seaport microgrids, requiring advanced forecasting techniques, are described in Chapter 2. Another challenge is that the integration of cold ironing with limited capacities increases the complexity of the existing seaside operation at port namely the berth allocation problem (BAP) and quay crane allocation problem (QCAP). It prolongs the waiting time for the ships to be served at berth. Thus, a seaside operational optimization model is developed in Chapter 3 to cooperatively schedule BAP, QCAP, and cold ironing assignment problems (CIAP). Chapter 4 integrates bilevel optimization as an energy management system (EMS) framework to coordinate the joint cold ironing with the seaport microgrid concept, providing more flexibility in energy scheduling while remaining cost-effective. Finally, Chapter 5 presents the overall conclusions of the thesis, research contribution, and future recommendations.
Most regulatory tools for low-carbon transition are jurisdiction-specific, respecting the principle of national sovereignty. Although possibly locally successful, they typically capture only scope 1 and scope 2 emissions. Value chains-related (scope 3) emissions remain largely unregulated. This is problematic, as global value chains are commonly organized across multiple jurisdictions with different climate policy ambitions. Products are often produced at different location than where they are consumed, and production-related emissions are transferred with the products. These emissions embedded in imported products amount to large volumes (e.g. in the EU estimated to about 30% of member state’s national emissions). This chapter gathers the scientific evidence on upstream scope 3 emissions and discusses the available regulatory toolbox for reducing those. Both private and public regulatory tools are represented as well as soft and hard regulatory tools, and modifications between those categories. The interactions between the various types of regulation are discussed with the aim to identify possible synergies and conflicts. The chapter takes the EU as its starting point and draws in examples from other jurisdictions where relevant.
As a reaction to an increasing concern with the decreasing of standards in shipping during the 1970s and 1980s the International Maritime Organization adopted the ISM Code, which became mandatory in 1998. This study revisits the ISM Code, firstly exploring the genesis of the code at the international level, and then its operationalization at the national and local level. Based on a three-step case study, the interplay between the essence of the ISM Code and praxis onboard is explored. The study explores the distortion and erosion of the essence of the ISM Code when implemented on the national level in Danish law (step one) and by two Danishbased companies (step two) and finally investigates the local effect of the code as it is displayed onboard (step three).
The study is conducted as an applied socio-legal study; thus, it adopts both an internal (doctrinal) and an external (empirical) approach. It also combines the topdown and bottom-up perspective, consequently applying different methods to fit the content of the different levels examined, while maintaining a qualitative approach.
The research design is inspired by the hermeneutic circle. The first circle (Part I the international level) explores the genesis of the ISM Code, aim to explore the causal explanation for and to determine the essence of the ISM Code. The ‘essence’ is constituted by the ‘principles’ that the regulators intended to be essential to achieve ‘the purpose’. With Santos’s cartographic metaphor as a theoretical analytical framework combined with legal dogmatic method, the first part concentrates on small-scale legality (the international level). The second circle (Part II) is related to medium-scale legality (the national/transnational level). Part II explore the operationalisation of the ISM Code as it is implemented in Danish law, applying legal dogmatic method, combined with analyses of written formal communication to identify the inter-legality that distort the principles when implemented at a national level (step one and two). The third circle (Part III) relates to large-scale legality, applying Goffman’s theoretical framework to analyse the micro level, that constitute the onboard praxis. Praxis is compared with legislation, v revealing a frontstage behaviour that is compliant with regulation and documented by checklists, while in fact praxis deviate, ‘to make it work’ the crew exhibits what Goffman denoted a backstage behaviour.
The ISM Code introduces meta-regulation as a regulatory mechanism. Metaregulation is linked to Santos’s concept of globalization and governance matrix; the study applies Parker’s definition of meta-regulation and the triple loop to study the concept.
The study identifies three principles that constitute the essence of the ISM Code; (1) to establish a genuine link between the company and the flag State; (2) to ensure that the company becomes responsible for the ship’s operation; and (3) to empower the master, ensuring her or his authority. The analyses proved that each of the three principals were distorted at respectively meso and micro level, and that even though the intent was to promote good ship management, in reality it has provided companies the opportunity strut in borrowed plumes.
Capacitors are fundamental electronic passive components and there are nearly everywhere. There are many different capacitors technologies, with different dielectric materials, form factors and terminals and housings available. This short encyclopedic article discuss the main capacitor types which are relevant for power electronic applications. The main types are Aluminum Electrolytic Capacitors, Metallized Film Capacitor, Ceramic Capacitors and Supercapacitors. The principal construction, materials and properties and technological limitations are discussed. Further new upcoming trends of new materials and designs are presented.
Studies have indicated that transportation noise is associated with higher cardiovascular mortality, whereas evidence of noise as a risk factor for respiratory and cancer mortality is scarce and inconclusive. Also, knowledge on effects of low-level noise on mortality is very limited. We aimed to investigate associations between road and railway noise and natural-cause and cause-specific mortality in the Danish population. We estimated address-specific road and railway noise at the most (LdenMax) and least (LdenMin) exposed façades for all residential addresses in Denmark from 1990 to 2017 using high-quality exposure models. Using these data, we calculated 10-year time-weighted mean noise exposure for 2.6 million Danes aged >50 years, of whom 600,492 died from natural causes during a mean follow-up of 11.7 years. We analyzed data using Cox proportional hazards models with adjustment for individual and area-level sociodemographic variables and air pollution (PM2.5 and NO2). We found that a 10-year mean exposure to road LdenMax and road LdenMin per 10 dB were associated with hazard ratios (95% confidence intervals) of, respectively, 1.09 (1.09; 1.10) and 1.10 (1.10; 1.11) for natural-cause mortality, 1.09 (1.08; 1.10) and 1.09 (1.08; 1.10) for cardiovascular mortality, 1.13 (1.12; 1.14) and 1.17 (1.16; 1.19) for respiratory mortality and 1.03 (1.02; 1.03) and 1.06 (1.05; 1.07) for cancer mortality. For LdenMax, the associations followed linear exposure-response relationships from 35 dB to 60–<65 dB, after which the function levelled off. For LdenMin, exposure-response relationships were linear from 35 dB and up, with some levelling off at high noise levels for natural-cause and cardiovascular mortality. Railway noise did not seem associated with higher mortality in an exposure-response dependent manner. In conclusion, road traffic noise was associated with higher mortality and the increase in risk started well below the current World Health Organization guideline limit for road traffic noise of 53 dB.