Lithium metal batteries offer a promising route to higher energy density than conventional lithium-ion batteries, but they suffer from severe lithium dendrite growth and rapid capacity decay. To address these issues, quasi-solid-state composite electrolytes (QSCEs) have emerged as a promising option by bridging the performance and processing gaps between inorganic and polymer solid electrolytes. Utilizing polymer matrices provides essential flexibility, facilitates lithium-ion transport, and ensures compatibility with commercial roll-to-roll manufacturing. Nevertheless, state-of-the-art QSCEs still fail to meet practical demands due to several intertwined challenges: (1) low room-temperature ionic conductivity (< 1 mS/cm) that limits fast charging; (2) a narrow electrochemical stability window (ESW) imposed by the poor high-voltage tolerance of conventional polymers; (3) the chemically and mechanically unstable interface against lithium anodes that triggers parasitic side reactions, increases interfacial impedance, and accelerates dendrite propagation. These combined deficiencies severely shorten cell-cycle longevity, thereby restricting the viability of QSCEs for long-term operations.

To overcome these severe limitations, recent research focus has shifted toward integrating ionic liquids (ILs) via IL-confinement strategies. In the combination of modifying polymers or fillers, these strategies successfully incorporate the unique properties of ILs, such as a wide ESW, inherent non-flammability, and high ionic conductivity, into the solid-like composite matrices. Motivated by these advancements, the overall goal of this thesis is to develop high-performance QSCEs with improved room-temperature ionic conductivity, a widened ESW, and robust interfacial stability with Li metal anodes by combining IL-confined strategies. The key advancements of this research are summarized as follows:

1. The review summarized and explored IL confinement in various quasi-solid-state electrolytes (QSSEs), including polymer/IL, host/IL, and polymer/filler/IL systems, discussing the impact of factors like substrates and confinement methods. It compared IL confinement in QSSEs with general IL confinement in other fields, noting that IL confinement enhanced electrolyte performance and differed significantly in the battery context. The study highlights that the specific influences between confined IL and bulk IL on electrolyte properties and performance remain unclear and require further investigation.

2. The effects of confined IL on electrolyte properties and performance were investigated, together with the Li+ transport mechanism. Confined QSCEs were prepared by confining IL within SiO2 (SiO2@IL-C), combined with LiTFSI and polyethylene oxide (PEO).  Compared to unconfined systems prepared by direct mixing, the confined electrolyte exhibited better properties, including higher ionic conductivity, an improved Li+ transference number, and over 1900 hours of stable stripping/plating cycles. The improved performance is attributed to a novel Li+ transport pathway (Li+ → SiO2@IL-C) in the confined electrolyte, which facilitates faster Li+ transfer and enhances overall electrochemical performance.

3. The impact of IL-confined thickness on Li+ diffusion and overall performance was further investigated. Electrolytes with different IL-confined thickness (SiO2@IL-C, different IL content on SiO2) were prepared.  The results demonstrate that adjusting IL layer thickness on  SiO2 allows the electrolyte to achieve superior ionic conductivity, a high Li+ transference number, and enhanced cycling durability; insufficient IL thickness narrows the effective Li+ migration region due to weak confinement, which impedes ion kinetics; conversely, an excessively thick IL film induces bulk-phase characteristics, thereby reducing ion transport. The electrolytes with optimized IL thickness enhance interfacial stability and electrochemical performance; specifically, LiFePO4//Li coin cells using the optimized electrolyte maintained 77.7% capacity retention after 700 cycles at 0.5 C. Theoretical calculations confirmed that this controllable confinement accelerates ion diffusion by constructing more efficient transport networks.

4. Based on the SiO2@IL filler, a fluorine-grafted gel polymer electrolyte (F–GPE) was developed. The F–GPEs demonstrate desirable properties, including high ionic conductivity (1.21 mS cm‒1 at 25 °C), a wide electrochemical window (5.20 V), and over 4000 hours of cycling stability in the Li//Li cells. When paired with a LiFePO4 cathode, it retains 98.8% capacity after 460 cycles; while with a high-voltage NCM622 cathode, it retains nearly 100% capacity after 350 cycles. The results revealed that fluorine reduces the interaction and coordination number of polymer-Li+ and forms a stable solid electrolyte interphase (SEI), thus enhancing the overall electrolyte performance.

5. The use of SiO2 may be hindered by its tendency to aggregate and its insufficient capability to form a robust SEI. To address these issues, GaN quantum dots (QDs) were introduced into PVDF-based GPEs to regulate overall performance. Due to the inherent properties of the QD materials, GaN QDs induce robust localized electronic states and internal fields an order of magnitude stronger than traditional fillers (e.g., SiO2). Benefiting from this, the GaN QD-based GPE achieves an over two-fold increase in both room-temperature ionic conductivity and Li+ transference number compared to GPEs without GaN QDs.  This regulation enhances electrochemical performance, enabling symmetric cells to cycle for over 5000 h at 1 mA cm–2 and full cells to exceed 2000 cycles in LiNi0.6Co0.2Mn0.2O2//Li.

Industrial systems now often operate in interconnected digital environments, where physical assets, software systems, engineering models, and organizational processes must be kept aligned throughout an industrial plant's lifecycle. Although modern industrial technologies enable data exchange and service integration across systems, connectivity alone does not ensure that the systems connected share an interpretation of what they exchange. That gap remains a significant barrier to interoperability, traceability, and the effective reuse of industrial knowledge.

This thesis investigates how ontologies and Semantic Web technologies can provide an explicit semantic layer for industrial systems of systems. It argues that semantic interoperability should not require replacing the systems, engineering tools, and standards already in use. Instead, independently developed representations can be connected through a shared, standards-grounded reference ontology while retaining the distinctions and purposes of their respective domains.

The work develops and applies this approach to industrial systems composed through a service-oriented architecture, using the Arrowhead framework as the concrete environment.

The Arrowhead Framework Ontology makes the configured structure of a running deployment available as a machine-interpretable knowledge graph, including which systems provide and consume which services. This representation is aligned with plant-design and lifecycle views through the Industrial Data Ontology, enabling relationships to be traced across operational, engineering, and asset-management contexts. The thesis further examines how different formal representations derived from the same running system support different analyses.

The findings show that explicit semantic representations can complement service-oriented architectures and digital-twin approaches by making relationships between systems, services, assets, and lifecycle information queryable, checkable, and open to inference. They support applications such as diagnosis, traceability, maintenance-oriented analysis, and cross-domain information integration.

An ageing population and a transition towards person-centred and integrated care create a growing need for health-promoting interventions that support healthy ageing among older adults. Social participation is an important determinant of health and well-being for older adults, yet social participation remains insufficiently addressed within health-promoting occupational therapy interventions, particularly in web-based formats.

The overall aim of this thesis was to explore and develop an understanding on how older adults’ social participation can be supported from individual, professional, and organizational perspectives. To achieve this, a stepwise research design was applied, informed by the Medical Research Council framework for developing and evaluating complex interventions. Four studies were conducted. Study I is a systematic review with a qualitative meta-synthesis of older adults’ experiences of using strategies to maintain and foster social participation. Study II is an exploratory case study examining older adults’ experiences of participating in the web-based occupational therapy group intervention Health Web, aiming to support older adults’ social participation. Study III is a convergent mixed-methods study evaluating feasibility and exploring preliminary intervention outcomes of Health Web. Study IV is a focus group study exploring organizational opportunities and challenges related to implementing health-promoting interventions for older adults, such as Health Web, within municipal health and social care.

Study I demonstrated that older adults strategically create and sustain routines for social participation through interconnected inward-looking and outward-looking strategies. Studies II and III provided insights into how strategies for social participation can be supported through the web-based occupational therapy intervention Health Web, with study II informing refinements of Health Web. Overall, findings from Studies II and III suggest that the intervention is feasible and acceptable and is perceived as valuable by occupational therapists and participating older adults. The findings further indicate that social participation can be supported by a combination of individual reflection, sharing of experiences within a group and the formulation of personalized goals. However, this potential was dependent on participants’ active engagement in both individual reflections and group dynamics, as well as their ability to participate in a web-based group format. This appeared to be facilitated when participants were fairly resourceful and had expectations aligned with the intervention’s content. Study IV highlighted that occupational therapists operate within organizational contexts that both enable and constrain health-promoting work. Organizational readiness for implementing health-promoting interventions was perceived as insufficient. The findings show that building organizational readiness requires coordinated, long-term efforts across the organization, rather than relying on specific professionals or isolated initiatives. For occupational therapy, these findings underscore the importance of engaging in ongoing dialogue, both within the profession and in interdisciplinary collaborations, on how more proactive and health-promoting approaches can be translated into everyday practice.

The findings of this thesis show how older adults’ social participation unfolds over time as a conscious and active process, in which choices of everyday activities play a central role. Supporting this process calls for a shift towards a more proactive, health-promoting approach in occupational therapy, where professionals facilitate older adults’ reflection and development of strategies for social participation. This, in turn, requires alignment across individual, professional, and organizational levels, supported by conditions that enable the implementation of health-promoting interventions. Taken together, these findings contribute knowledge on how occupational therapy expertise can be more effectively utilized in proactive health-promoting practice and provide a foundation for continued evaluation and future implementation of Health Web.

This thesis explores how architectural knowledge contributes to New Product Development (NPD) in the Swedish timber building industry and how the architect's role is affected as design moves beyond the architectural office and into long-term industrial development processes. The research draws on five applied research projects conducted between 2013 and 2026, focusing on the development process of prefabricated timber façade systems for new construction, renovation, reuse, and adaptation to architectural contexts.

The starting point was a perceived gap between architectural practice and product development in the timber building industry. This gap has become increasingly important as the construction sector faces growing demands for circularity, digitalization, resource efficiency, renovation, and industrialization. While architects are often associated with shaping a building’s form and early design phases, engineers, manufacturers, and production specialists typically drive building-system development. At the same time, growing demands for circularity, digitalization, resource efficiency, and adaptability to architectural context for prefabricated timber building systems suggest new forms of collaboration across the value chain. This raises questions about what architectural knowledge can contribute to NPD processes. To discuss this, the research adopts a Research-through-Design approach, combining co-design, prototyping, workshops, interviews, digital tool development, and full-scale testing. As an architect and researcher embedded in the projects, I tracked how ideas, materials, digital models, prototypes, Design Criteria, and façade systems evolved over time and shaped collaboration among architects, manufacturers, engineers, researchers, property owners, and material suppliers. A central finding is that architectural knowledge contributes to NPD not primarily through form-giving, but through its capacity to connect and negotiate aesthetic, material, technical, contextual, and circular concerns. Architectural knowledge further contributed by framing, visualizing, materializing, and coordinating design intentions across organizational and disciplinary boundaries, enabling the development of prefabricated façade systems capable of accommodating technical requirements, architectural variation, contextual adaptation, and future reuse. Across the five applied research projects, boundary objects became crucial for this process. Boundary objects such as Design Criteria, prototypes, material samples, digital models, workflows, and façade systems enabled different forms of knowledge to meet, be challenged, and gradually stabilize into shared decisions and façade systems. Rather than operating as passive representations, these boundary objects actively shaped discussions, exposed conflicts, supported learning, and enabled collaboration across disciplinary boundaries. Prototyping played a particularly important role by making assumptions visible, allowing architectural intentions to be tested against material, technical, and manufacturing constraints, and supporting negotiation between different actors throughout the development process.

The findings further suggest that digital tools and workflows are not neutral instruments. They influence what knowledge becomes visible, what discussions become possible, and what architectural intentions survive as projects move towards manufacturing and implementation. Similarly, circularity became effective when it was embedded in systems, materials, joints, workflows, and future use scenarios. Architectural knowledge contributed to the development of façade systems designed not only for immediate implementation but also for adaptation, renovation, reuse, and future transformation. Across projects, architectural knowledge informed design criteria, workflows, prototypes, digital tools, and collaborative frameworks by translating architectural intentions into industrial practice. The boundary objects functioned as both development outcomes and vehicles for knowledge generation and exchange. The façade systems and prototypes represent materialized negotiations between architectural intentions, material behavior, manufacturing requirements, digital processes, and circular ambitions. The façade systems, rather than being understood as fixed products, function as boundary objects, an adaptable framework together with the other boundary objects, supporting design variation, contextual adaptation, renovation, and future transformation.

Taken together, the findings suggest a repositioning of architectural agency within NPD in the timber building industry.  The architect's role expands from form-giver to system developer, mediator, facilitator, and curator of socio-material relations, and contributor to long-term industrial innovation. Architectural influence depends not only on what architects know, but on how that knowledge becomes embedded in boundary objects, systems, materials, and collaborative processes. The findings indicate that architects contribute not only by coordinating multiple forms of expertise, but also by envisioning possibilities, framing future use scenarios, and translating abstract architectural knowledge into material and operational realities. The thesis argues that these capacities are increasingly important as the timber building industry moves towards more circular, digitalized, and industrialized forms of development.

This doctoral project is grounded in my own practice as a professional clarinettist and situated within the field of artistic research. The aim is to design electro-acoustic instrumental systems that enable similar complexity, proprioceptive feedback and artistic depth as in the interaction between a performer and an acoustic instrument. Three research questions guide the project: 1) What is required in the design of an electro-acoustic instrumental system to enable the creation of musical works which display complexity, feedback and artistic depth in the interplay between the performer and the system? 2) How can a multimodal understanding of musical gesture contribute to the design of an interactive electro-acoustic instrumental system? 3) How can the affordances of interactive systems for music performance be artistically exploited, explored and analysed through artistic collaborations and reflexive methods?

Three longitudinal artistic laboratories have served as the sites for the exploration of electro-acoustic instrumental systems that I have designed and utilised in my artistic practice: The first focuses on performer-instrument relations in gestural space, and how resistance, affordances, and interaction can be integrated into EAI systems. The second explores artistic approaches for remote distributed interaction among musicians, instruments, and performance environments. The third investigates how expressive musical gestures can be analysed, modelled, and transformed into forms of agency within EAI and AI-augmented musical systems. Together, these laboratories explore different aspects of embodiment, agency, collaboration, and interaction design in EAI systems.

Performing with EAI systems requires a close relationship with, and an intimate understanding of the system, as well as the specific relationship between the performer’s body and the sound-producing techniques and technologies employed. The exploratory nature of the project moves forward in an iterative process in which designing and performing within these systems develop in parallel with observational and reflexive analysis. Stimulated recall analysis has served as the primary reflexive methodology. However, because a significant part of musical performance operates through the body schema and therefore remains inaccessible to conscious reflection, stimulated recall alone cannot account for all the experiential dimensions of performance. For this reason, a series of quantitative methods have complemented the qualitative approaches. As the project developed, the combination of methods became more elaborate, introducing machine learning and Laban Effort analysis in real-time to detect and model expressive gesture. Hereby, a deeper understanding of how gestures carry musical meaning was also transferred to embodied music performance in the EAI systems.

Across all three laboratories, the most successful artistic scenarios were those where the systems remained responsive yet capable of surprise, offering the performer neither full control nor complete unpredictability. The EAI systems became spaces for negotiation, where expressive gestures, listening strategies, instrumental affordances, technological processes, and the actions of both human and non-human actors continuously interacted and influenced each other to shape musical outcomes. Over time, these systems shifted from mere instruments to collaborators, and from design objects to active participants in the creation of music.

The main contribution of this thesis is a framework for understanding EAI systems through the interconnected manifestations of resistance, affordances, expressive gestures, and agency. From this viewpoint, designing EAI systems is not just a technical task but an artistic process of shaping relationships between performers, technologies, and sounds. It is through these relationships and the tensions they create that new forms of musical expression emerge.

Inom gruvindustrin genomförs teknisk utveckling och hållbar omställning genom människors arbete och lärande i arbetets praktik, inte enbart genom nya tekniska system, organisatoriska strategier eller politiska ambitioner. Teknisk utveckling och hållbar omställning förändrar arbetsuppgifter, arbetssätt och kompetenskrav, vilket gör arbetsplatslärande centralt för hur förändringsprocesser genomförs och får genomslag. Trots att gruvindustrin genomgår omfattande förändringar finns det begränsad kunskap om hur dessa förändringar omsätts i gruvarbetets praktik och vilka konsekvenser de får för gruvarbetares arbetsplatslärande och kompetensutveckling. Syftet med denna avhandling är att bidra med fördjupad kunskap om hur arbetsplatslärande och kompetensutveckling formas i gruvarbetets praktik i relation till teknisk utveckling och hållbar omställning.

Avhandlingen bygger på fyra delstudier som tillsammans belyser det övergripande syftet ur olika perspektiv. Delstudierna omfattar en litteraturöversikt och empiriska studier i form av en webbenkät med experter från gruvrelaterade verksamheter samt workshops, intervjuer och fokusgruppsdiskussioner med anställda inom den svenska gruvindustrin. Det kvalitativa empiriska materialet har huvudsakligen analyserats med reflexiv tematisk analys. I den fjärde delstudien samt i kappans analys- och diskussionskapitel har praktikgemenskaper (Lave & Wenger, 1991/2008) och arbetarkollektivet (Lysgaard, 1961) använts som teoretiska perspektiv.

Gruvarbetares arbetsplatslärande och kompetensutveckling formas till stor del i det dagliga arbetet genom erfarenhetsutbyte, gemensam problemlösning och andra kollektiva praktiker där kunskap utvecklas, delas och prövas. Dessa kollektiva lärpraktiker skapar samtidigt förutsättningar för att hantera förändrade arbetsuppgifter, tekniska system och kompetenskrav. När arbetsuppgifter och kompetenskrav förändras omförhandlas kontinuerligt vad som erkänns och värderas som relevant yrkeskompetens. Gruvarbetarnas möjligheter till arbetsplatslärande beror dock även på organisatoriska förutsättningar, exempelvis tid, resurser och utrymme för kunskapsutbyte och gemensam problemlösning.

Det finns en diskrepans mellan gruvrelaterade experters begränsade tilltro till gruvarbetares vilja och förmåga att utveckla sin kompetens och gruvarbetarnas egna beskrivningar av lärande och kompetensutveckling som en självklar del av arbetet. Gruvarbetarna uttrycker en stark vilja att utveckla den kompetens som krävs när arbetet förändras. Denna diskrepans är betydelsefull eftersom föreställningar om gruvarbetares vilja och förmåga att lära kan påverka hur kompetensutveckling organiseras och vilka insatser som prioriteras.

Gruvarbetarna utvecklar kompetens för att möta förändringar men är även aktiva medskapare i hur förändringarna tar form i arbetets praktik. De producerar därmed inte enbart malm utan också den kompetens som krävs för att teknisk utveckling och hållbar omställning ska kunna omsättas i gruvarbetets praktik. Organisationer behöver därför skapa långsiktiga förutsättningar för det arbetsplatslärande och den kompetensutveckling som förändringarna kräver.

Thermal processes can alter both the optical and physical properties of airless planetary surfaces. On Mercury, intense solar irradiation may modify the spectral properties of surface materials, affecting the interpretation of remote-sensing observations. On asteroids, repeated diurnal temperature variations generate thermoelastic stresses that can drive crack growth and contribute to rock breakdown and regolith production. However, the efficiency of these processes depends on the properties of the material being exposed, and it remains uncertain whether damage due to thermal fatigue continues to accumulate under repeated similar thermal cycles.

This thesis investigates the material dependence of thermal space weathering through laboratory experiments on Mercury analogue rocks and meteorites representing asteroid surface materials. Six terrestrial silicate rocks were exposed to high solar irradiance under vacuum, corresponding to the solar flux at Mercury’s perihelion, and their visible and near-infrared reflectance spectra were measured before and after irradiation. Most materials underwent permanent darkening and reddening, although the magnitude of the spectral alteration varied substantially between the samples. Due to their low albedo, boninite, basalt, and diorite experienced the most significant spectral changes.

The mechanical response of asteroid analogue materials was investigated by subjecting five meteorites to 100 thermal cycles of DT = 190 K. The meteorites used were the CM2 Aguas Zarcas, CV3 Allende, H3–5 Oum Dreyga, L3 Aba Panu, and LL5 Chelyabinsk. For the first time, acoustic emission (AE) monitoring was applied to meteorites during thermal cycling to detect fracture activity in real time. Carbonaceous chondrites generally produced greater and more distributed AE activity, whereas ordinary chondrites generated fewer events and showed stronger evidence of damage saturation. RA–AF and Gutenberg–Richter b-value analyses further showed that the character and evolution of fracture activity differed between meteorite materials, while X-ray microtomography revealed structural modification of pre-existing cracks in selected samples.

A central finding is that fracture activity did not accumulate continuously with increasing numbers of identical thermal cycles. Instead, AE activity generally decreased as cycling progressed and the samples approached saturation regimes. Thermal fatigue appears to be controlled by evolving damage state and stress history of the material, and this behaviour is consistent with a threshold-controlled response such as the Kaiser effect, in which previously experienced stress conditions produce progressively less new fracture activity unless new stress thresholds are exceeded.

The results demonstrate that thermal space weathering cannot be described solely by the magnitude of the imposed thermal or radiative environment. The spectral alteration of Mercury analogue materials and the fracture response of meteorites are both strongly controlled by material properties, while thermal-fatigue efficiency also depends on previous stress history. Thermal fatigue on asteroid surfaces may therefore operate most efficiently when fresh material is exposed or when changing environmental or mechanical conditions introduce new stress states. These results provide experimental constraints for interpreting the spectral evolution of Mercury and the mechanical degradation and regolith production of asteroid surfaces.

Industrial providers engaged in digital servitization increasingly face the challenge of leveraging advanced digital technologies while supporting customers in improving their environmental and social sustainability performance. Meeting these objectives requires industrial providers not only to digitalize their own offerings but also to enable sustainability improvements within customer operations. Against this backdrop, many industrial providers are shifting from traditional product-centric models towards digitally enabled solutions that combine operational performance with sustainability outcomes. However, realizing this potential remains difficult. Digital solutions must be integrated with existing equipment, infrastructures, and data environments, while their use may require corresponding changes in organizational routines, skills, responsibilities, and decision-making practices. These interconnected technical and social challenges extend to providers, customers, and ecosystem partners and become more complex as digital solutions are extended across heterogeneous industrial environments. Consequently, supporting industrial sustainability through digital servitization constitutes a socio-technical alignment problem.

Accordingly, this thesis investigates how industrial providers engaged in digital servitization align socio-technical systems – internally, with customers, and across ecosystem partners – to support industrial sustainability. It adopts a socio-technical systems perspective and views digital servitization as a socio-technical alignment process in which technologies evolve in alignment with organizational routines, decision-making practices, and inter-organizational relationships. The thesis is based on four interrelated qualitative studies that draw on semi-structured interviews, publicly available podcast interviews, and complementary materials.

Paper 1 examines the interacting economic, technological, market, and sustainability-related conditions that drive industrial providers’ engagement in digital servitization. Paper 2 examines how industrial providers support customers in aligning digital solutions with customer infrastructures, organizational routines, and operational practices to support industrial sustainability. Paper 3 analyzes how differences in power dynamics and sustainability focus among industrial actors shape ecosystem configurations and the conditions under which sustainability-oriented change unfolds. Paper 4 investigates how industrial providers coordinate intra-organizational, customer, and ecosystem practices to scale digital solutions beyond localized implementations.

Through an integrative synthesis of the four studies, the thesis develops a three-phase framework comprising exploring solution viability, operationalizing solutions, and scaling solution implementation. The framework explains how the socio-technical alignment problem evolves from reducing uncertainty around emerging digital solutions, through embedding workable socio-technical arrangements in customer operations, to making these arrangements sufficiently repeatable and adaptable across heterogeneous contexts. Across this process, socio-technical alignment extends within industrial providers and across customer and ecosystem boundaries. The associated outcomes progress from demonstrated sustainability potential, through realized sustainability value, to scaled sustainability value.

The thesis contributes to digital servitization research by conceptualizing digital servitization for industrial sustainability as an unfolding socio-technical alignment process across organizational boundaries. It further conceptualizes industrial providers as socio-technical change agents that support the technical and organizational changes required to realize sustainability value beyond specific contexts. Finally, it shows that scaling digital servitization requires broader socio-technical configurations surrounding digital solution use to make them sufficiently repeatable and adaptable across heterogeneous contexts. These insights advance understanding of how industrial providers can translate the sustainability potential of digital servitization into realized sustainability value and extend this value across broader industrial contexts.

Additive manufacturing (AM) makes it possible to manufacture complex metallic components. Changes in the manufacturing conditions can result in variations in microstructure, defects, and mechanical properties. Characteristically, AM components are anisotropic and vary locally. Understanding these variations can help control the microstructure and material quality. Therefore, a reliable non-destructive tool for material assessment beyond defect detection is required. Ultrasound is a promising tool for this purpose because it is fast, safe, scalable to component size, and sensitive to changes in mechanical properties of the material. This thesis focuses on how ultrasound can be used to assess and interpret the variations in 316L stainless steel components manufactured using Laser Powder Bed Fusion (LPBF). 

The work starts with establishing a relationship between ultrasound, manufacturing conditions, and material properties. The first studies used power spectral density from the ultrasound signature along with multivariate modelling. The focus is on distinguishing samples based on manufacturing parameters and to predict resulting material properties. The next part of the thesis moves towards physically interpretable quantities obtained from frequency dependent acoustic properties. These are used to observe changes in the material due to post-processing (heat treatments). The last study evaluates the directional differences in the samples manufactured using different layer heights. These directional ultrasound features are used to classify the samples into their respective groups and provide information regarding manufacturing consistency. 

Evaluating the model’s performance and prediction uncertainty is important to establish the consistency of the developed models. Therefore, appropriate validation and uncertainty assessment were applied throughout the thesis. Where required, material characterization was used to support ultrasound-based claims and provide a basis for comparison. The material characterization was aimed at providing information about the microstructural features, porosity content, grain morphology and texture, etc. The results show that the ultrasound response changes with manufacturing conditions, post-processing treatments, and the resulting material properties of LPBF 316L steel. Overall, the thesis develops ultrasound as a non-destructive evaluation tool to identify and interpret material variability. The research can prove vital for analyzing microstructural homogeneity, process optimization, and ensuring the quality of AM components. 

The thesis is divided into two parts. Part I presents the background, methods, research contributions, conclusions, and future work, while Part II contains the publications included in the thesis.

The increasing demand for high-performance materials must be considered within the context of finite resources and growing sustainability challenges. As the availability of raw materials becomes increasingly constrained, it is necessary to consider not only what is consumed, but also how existing materials can be used more efficiently through advances in processing, recycling, and manufacturing. In this context, resource efficiency is no longer limited to reducing consumption; it also involves extending the useful life of materials already extracted from the environment.

One way to achieve this is by recovering and reusing materials at the end of their service life. Rather than being treated as waste, materials can be reintroduced into the value chain through routes that maximize their retained value while minimizing environmental impact. Recycling therefore becomes more than a waste-management strategy; it becomes a means of improving resource efficiency and supporting the transition toward more circular material systems.

Within this framework, recycled carbon fiber (rCF) emerges as a material of growing interest. Recovered from end-of-life composites and manufacturing waste, rCF offers the possibility of retaining much of the value embedded in carbon fibers while avoiding the environmental burden associated with producing virgin carbon fiber (vCF). However, recycling does not reproduce the original material exactly. The recycling process modifies the fibers through thermal exposure, oxidation, and repeated handling, resulting in changes to their structure, surface condition, and performance. Consequently, rCF should not be considered a direct replacement for vCF, but rather a material with its own characteristics, capabilities, and limitations.

The work presented in this thesis demonstrates that carbon fibers can be recovered with high quality through thermal recycling when pyrolysis and oxidation are carefully controlled. The results show that stiffness can be largely preserved, whereas strength is more sensitive to oxidation damage and the accumulation of surface defects. Studies on repeated recycling further reveal that the properties of rCF evolve with recycling history, highlighting the importance of considering recycled fibers as a distinct material system with its own performance window rather than as a degraded version of virgin fibers.

A thorough characterization of recycled fibers is therefore essential. While mechanical properties remain central for structural applications, the performance of rCF cannot be understood solely through stiffness and strength. Surface chemistry, wettability, and fiber–matrix interactions also play a critical role in determining the quality of the composites manufactured from recovered fibers. The findings of this thesis show that recycling affects the fiber surface more significantly than the bulk structure and that these surface modifications strongly influence interfacial behavior. Although re-sizing treatments can improve wettability, they cannot fully compensate for damage introduced during recycling, emphasizing the importance of carefully controlling recycling conditions.

The practical value of rCF ultimately depends on how it is used in new products. Because recycled fibers are typically discontinuous, their most promising applications are found in short-fiber composite systems where the limitations imposed by fiber length are less critical. The manufacturing studies presented in this thesis demonstrate that wet-laid processing provides an effective route for producing homogeneous mats and reproducible laminates from virgin, recycled, and hybrid fiber systems. The resulting composites show that recycled fibers can retain significant stiffness, while hybrid architectures combining virgin and recycled fibers can recover a substantial portion of the strength losses associated with recycling and provide a balance between performance and sustainability.

This thesis lies at the intersection of recycling, characterization, remanufacturing, and environmental assessment. Its overarching objective is to improve the understanding of how recycled carbon fibers can be recovered, characterized, processed, and evaluated to support their integration into more circular and resource-efficient composite systems. The results demonstrate that rCF should not be viewed simply as a lower-performance alternative to virgin carbon fiber, but rather as an emerging material system with its own technical, manufacturing, and sustainability profile. By preserving much of the intrinsic value of carbon fibers while reducing the environmental burden associated with new material production, rCF creates opportunities for new material and product concepts that balance performance, resource efficiency, and sustainability. Ultimately, the findings show that the successful use of recycled carbon fibers depends not only on how closely they replicate virgin materials, but also on understanding and exploiting their own unique capabilities, limitations, and potential contributions to future composite design.

Collaborative writing (CW) is on the rise in primary English as a foreign language (EFL) education, which warrants further research on the opportunities and challenges of CW with young learners. The present thesis aims to contribute with knowledge about pedagogical implications of CW in EFL instruction at primary school. More specifically, affordances of CW are explored in four empirical studies targeting EFL teachers and young learners (aged 11–12) in Swedish school years 4–6. These studies build on qualitative interviews with teachers, audio- and screen recordings of young learners’ computer-mediated CW in pairs, post-task interviews with CW pairs and handwritten narrative learner texts produced individually and collaboratively. The thesis is theoretically informed by affordance theory, while also drawing on teacher beliefs, social deontics and systemic functional linguistics (SFL). Methods employed include reflexive thematic analysis, and transitivity and appraisal frameworks, which are tools situated in SFL. The findings highlight affordances of CW from teachers’ and young learners’ perspectives, operationalised as actions taken that shape EFL learning opportunities. Such affordances encompass (meta)linguistic, social and affective aspects. (Meta)linguistic affordances, such as the potential of CW to enhance vocabulary knowledge, are emphasised by teachers as well as by young learners. The comparative analyses of the narrative texts also reveal linguistic affordances of CW, since texts written collaboratively use evaluative language to a greater extent than individual texts and are therefore potentially more engaging to a reader. When constructing the narrative texts, (meta)linguistic affordances offered by peer/teacher support and Google Translate are frequently enacted by the young learners. The use of this digital tool can, however, encourage or discourage pairs’ joint discussions about language, and their critical awareness of suggestions made by Google Translate varies greatly. In addition, peer support and the CW situation are affected by social relationships formed either prior to or during CW, which fluctuate in interaction and are shown to influence EFL learning opportunities. As an example, the teachers voice concerns about how to pair young learners to stimulate language learning and ensure collaboration, and classroom data confirm this challenge. The teachers further assign CW a motivational role in primary EFL education, which exemplifies a prominent affective factor and positions CW as not merely a (meta)linguistic practice. The results thus indicate that CW is a multifaceted activity and, as such, may require considerable pedagogical efforts on behalf of the teacher.

Reliable localization and mapping in GPS-denied and perceptually degraded environments remain critical challenges for autonomous robotic systems, particularly in subterranean settings characterized by smoke, dust, low visibility, extreme temperatures, and uneven terrain. These challenges are further exacerbated by the difficulty of identifying temporal sensor failures, which are not effectively handled by single Kalman filter implementations or conventional centralized fusion architectures. In such cases, erroneous measurements can propagate through the estimation process and degrade overall fusion performance. Moreover, existing decentralized fusion approaches often fail to fully prevent corrupted measurements from influencing the final state estimates. To address these limitations, this thesis introduces a Fault Resilient Optimal Information Filter (FROIF), integrated with both classical and learning based fault detection mechanisms. The proposed framework adopts a multi-layer decentralized fusion strategy to improve robustness across ground, aerial, and space robotic platforms. A threshold based validation mechanism is applied at each time step to identify faulty sensor measurements. Based on this detection outcome, the FROIF framework eliminates the contribution of corrupted sensor estimates and their associated covariances from the final fusion stage, ensuring that faulty measurements do not influence the global estimate. In contrast, existing methods typically reduce the impact of such measurements rather than fully removing them. Collectively, the proposed frameworks enhance fault resilience and reliability in multi-sensor fusion. Furthermore, an autoencoder based approach is introduced to evaluate and compare classical and learning based fault detection methods within both centralized and decentralized fusion architectures. 

Within multi sensor fusion pipelines, smoke and fog are observed to be the dominant causes of LiDAR failure. Consequently, this thesis focuses on radar inertial odometry as a complementary modality to improve robustness in degraded environments. Initially, cost-effective mmWave radars with a Pixhawk IMU are used, with multi-directional radars mounted on a ground mobile platform. During experiments in Sub-T with these sensors, it was found that the IMUs exhibit dynamical acceleration bias in the presence of extreme cold and tunnel slopes in a ground mobile robot, where the x component of the gravity vector is projected onto the acceleration of the vehicle along the forward axis, thereby introducing a dynamical bias in the measured acceleration. In addition, radar point clouds differ fundamentally from LiDAR data, being inherently sparse, noisy, and prone to flickering effects, which further complicates achieving stable and reliable odometry with prior EKF-RIO frameworks. To address these challenges, this thesis presents a novel two-stage multi-radar inertial odometry (MRIO) framework for resilient localization and mapping in GPS-denied subterranean environments. In the first stage, radar ego-velocity estimation, formulated through a least-squares approach, is incorporated into an Extended Kalman Filter (EKF) for IMU bias correction. The resulting drift free accelerations are then fused in the second stage with measurements from multiple radars and the IMU to refine odometry performance. Beyond odometry, the framework also supports radar based mapping by leveraging the robot's translational and angular displacement. Starting with a range based outlier filter and least-squares ego-velocity reconstruction, the MRIO framework enables robust ego-velocity estimation, localization, and mapping using radar and IMU measurements. The proposed methods are extensively validated through real-world experiments in GPS-denied subterranean tunnels, including smoke-filled environments and long-duration trajectories. Experimental results demonstrate significant improvements in localization accuracy, drift reduction, and robustness compared to prior radar inertial odometry approaches. 

Since LiDAR provides accurate geometric information under nominal conditions but degrades in the presence of smoke, dust, and other airborne obscurants, this thesis investigates LiDAR radar fusion through two complementary formulations. The first employs proactive LiDAR degradation detection for reliability-aware adaptive localization, while the second uses decentralized fault resilient fusion with adaptive residual thresholding to identify and isolate unreliable estimates. In the first formulation, LiDAR-inertial odometry (LIO) serves as the primary localization modality, whereas radar inertial odometry (RIO) provides a more robust alternative under degraded visibility. LiDAR reliability is estimated using a one-class temporal learning framework that combines degradation sensitive spatial, geometric, motion, cross-modal, intensity, and measurement recency features. These features are arranged over sliding temporal windows and processed by an LSTM autoencoder trained exclusively on nominal LiDAR data, enabling degradation to be detected without labelled failure examples. The resulting reconstruction error is used as a reliability indicator: LIO  based localization is considered during nominal operation, while localization switches to RIO when LiDAR degradation or measurement loss is detected. The framework is evaluated on real-world ground-robot datasets collected in GNSS-denied subterranean tunnels under nominal and dense-smoke conditions, demonstrating effective degradation detection, adaptive LIO-RIO switching, and continued localization during severe LiDAR impairment. An ablation study further shows that a reduced feature set can improve performance in dense smoke scenarios, highlighting the importance of feature parsimony in one-class sensor health monitoring.

The deployment of autonomous robots for close-proximity applications involving physical interactions with other robots or external infrastructure has shifted the focus of control design toward safety during interaction. In these applications, safety violations may lead to undesired collisions and catastrophic failure. Ensuring safety becomes particularly challenging in the presence of parametric uncertainties in the system dynamics. Moreover, when an externally planned safe trajectory is unavailable, the controller must generate the required motion toward the target while inherently enforcing the safety requirements. Accordingly, this dissertation proposes two control approaches to address two fundamental challenges: enforcing strict constraints during trajectory tracking under parametric uncertainties, and formulating state constraints that enable safe physical interaction through reactive control.

The first part of this dissertation presents a tracking controller that tracks a preplanned trajectory for physical interaction while accounting for parametric uncertainties without requiring a priori knowledge of the system dynamics or the bounds of the uncertainties. An adaptive controller is formulated using a Barrier Lyapunov function to enforce strict constraints on the position, orientation, and velocities of the system. The stability of the controller is analyzed using a Lyapunov-like method, and its performance is validated using a space-docking hardware.

The second part presents a control barrier function (CBF)-based safety-critical controller that enables safe close-proximity operations without requiring an externally planned trajectory. Task-specific CBF constraints are formulated for aerial physical interaction, space docking, and UAV landing, and imposed over a nominal go-to-goal controller. The validity of the CBFs is analyzed theoretically, and the resulting controllers are demonstrated through simulation and hardware experiments. The UAV landing framework is further extended to multi-robot and large-scale heterogeneous aerial-ground task execution using centralized and edge-based hybrid centralized-decentralized control architectures.

The third part extends the CBF framework toward two real-world deployment scenarios involving perception limitations and implementation uncertainties. The first scenario considers UAV navigation between two surface vehicles and landing in an outdoor environment with limited visual localization. The control framework incorporates perception constraints for navigation and an adaptive controller to compensate for external disturbances and unmodeled uncertainties. The second scenario considers navigation through cluttered environments with unknown obstacle geometry, where a composite CBF formulation is constructed directly from onboard point-cloud measurements for autonomous infrastructure inspection.

Together, the thesis provides control frameworks for safe close-proximity robotic operations by addressing uncertain dynamics, the absence of reliable externally planned trajectories, multi-robot coordination, and real-world deployment challenges.

Total joint replacement is an established treatment for restoring mobility and improving quality of life in patients with severe joint degeneration. Despite its clinical success, long-term implant performance can be compromised by wear, wear-debris generation, and degradation at articulating interfaces. Ultra-high molecular weight polyethylene (UHMWPE) remains the clinical benchmark for polymeric bearing materials; however, increasing demands for implant longevity, particularly for younger and more active patients, continue to motivate the development of alternative biomaterials and manufacturing strategies.

Polyaryletherketones (PAEKs), particularly polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), are promising candidates for orthopaedic applications because of their favourable mechanical properties, chemical stability, radiolucency, and biocompatibility. Additive manufacturing offers further opportunities to fabricate complex and patient-specific components, but introduces processing-dependent variations in material structure and surface characteristics. Understanding how these processing-induced variations translate into bearing performance is therefore essential for the development of additively manufactured PAEK-based materials.

This thesis investigates the relationships between processing, material structure, interface evolution, and functional performance in additively manufactured PAEK-based biomaterials. A systematic review first established the state of knowledge and identified limitations in the processing, mechanical performance, and tribological evaluation of additively manufactured PAEKs for load-bearing biomedical applications. Building on these gaps, the processing–structure relationship of fused filament fabricated pseudo-amorphous PEKK was investigated through controlled thermal post-processing. Annealing produced crystallinity levels of up to 27% and increased the storage modulus by 44%, while also inducing crystallization-related dimensional changes. Annealing at 200 and 260 °C promoted form II crystals, whereas annealing at 300 °C favoured form I crystals. Thermal post-processing therefore enabled control of the structure and thermomechanical response of printed PEKK, although structural development had to be balanced against dimensional stability.

The tribological and tribocorrosion behaviour of additively manufactured PEEK was subsequently investigated against cobalt–chromium (CoCr) alloy under simulated physiological conditions and compared with conventionally processed PEEK and UHMWPE. Differences associated with the PEEK manufacturing routes were minimized when the surfaces were polished to comparable roughness, highlighting the influence of surface condition on tribocorrosion. CoCr nevertheless exhibited at least twice the charge transfer when sliding against PEEK compared with UHMWPE, indicating greater electrochemical degradation and a greater potential for metal-ion release. Serum lubrication reduced charge transfer compared with phosphate-buffered saline, further showing that the interfacial response depended on the lubrication environment.

The potential to modify the articulating interface was investigated using PEEK composites containing hexagonal boron nitride (hBN) and silicon nitride (Si₃N₄), produced by melt compounding and fused filament fabrication. Under simulated joint conditions, hBN reinforcement reduced friction by approximately 20% and wear by approximately 50%, whereas Si₃N₄ increased friction by approximately 40% and caused pronounced damage to the CoCr counterface. Subsequent testing across different counterfaces and lubricant environments showed that hBN promoted lower and more stable friction and reduced electrochemical activity, whereas micro-sized Si₃N₄ increased abrasive interactions and destabilised the tribocorrosion response. Lubricant chemistry also altered the balance between friction and wear: phosphate-buffered saline produced lower friction but greater wear, whereas bovine serum increased friction while reducing wear, particularly against zirconia-toughened alumina. The effectiveness of reinforcement therefore depended on the combined effects of filler characteristics, counterface material, and lubrication environment.

Collectively, these findings show that the performance of additively manufactured PAEK-based biomaterials emerges from coupled processing–structure–interface–performance relationships. Processing determines the initial material state and surface characteristics, while the subsequent evolution of the articulating interface is governed by interactions among the polymer, counterface, reinforcement, and lubrication environment. By connecting material processing with tribological and tribocorrosion behaviour, this thesis provides a mechanistic basis for the design, evaluation, and further development of additively manufactured PAEK-based biomaterials as polymeric bearing materials for total joint replacement.

This thesis investigates the behavior of platinum-group elements (PGE) and the mineralogical evolution of platinum-group minerals (PGM) from hypogene to supergene environments, with particular emphasis on whether PGM can form in-situ during lateritization. The origin of PGM in supergene environments remains debated, with contrasting models involving i) the inheritance and mechanical liberation of hypogene PGM during weathering, versus ii) their in-situ formation following PGE mobilization and reprecipitation. At the Falcondo Ni-laterite deposit (Dominican Republic), Pt-Ir-Fe-Ni grains found in a highly weathered chromitite hosted in limonite and characterized by a positive Pt anomaly in chondrite-normalized PGE patterns have previously been interpreted as possible products of neoformation in the lateritic soil. These grains show complex porous textures and occur as accumulations of Pt-Ir-Fe-Ni nanoparticles within Fe-oxyhydroxides. Their occurrence in the upper part of the lateritic profile and their textural relationships with Fe-oxyhydroxides have been used to support PGE mobilization and in-situ PGM growth during lateritization. However, alternative interpretations involving alteration of pre-existing PGM, dissolution, short-distance remobilization, and reprecipitation have also been proposed. Hence, the origin of the Pt-Ir-Fe-Ni alloys remains unresolved.

To investigate this problem, three case studies representing different stages in the evolution of PGM from hypogene to supergene environments were examined: the PGE-rich chromitites of the Herbeira Massif in the Cabo Ortegal Complex (Spain), the Santa Cruz Ni-laterite deposit in Acoje (Philippines), and the Falcondo Ni-laterite deposit. The Herbeira chromitites provide a hypogene reference for the study of primary magmatic PGE concentration in ultramafic rocks and subsequent PGM modification by hydrothermal-related processes, whereas investigation of the Ni-laterites from Santa Cruz and Falcondo allows the study of the behavior of PGE and PGM during intense tropical weathering of ultramafic rocks.

At Herbeira, the PGE-rich chromitites are characterized by enrichment in Pd-group PGE (PPGE: Rh, Pt, and Pd) relative to Ir-group PGE (IPGE: Os, Ir, and Ru) and abundant PGM dominated by Rh-Ir-Pt-bearing arsenides and sulfarsenides, Pt-Ir-Pd-base-metal-bearing alloys, and Pt-Pd-bearing sulfides, commonly associated with base-metal sulfides. Their formation is related to magmatic processes, whereas subsequent post-magmatic processes related to the circulation of hydrated fluids during amphibolite-facies metamorphism that affected these rocks, promoted local PGE mobilization and the alteration of primary PGM into secondary PGM phases. This modification produced porous Pt-bearing alloys and complex PGM textures composed of PGE- and base-metal-bearing nanoparticles, interpreted to result from the mobilization, precipitation, and reorganization of PGE during interaction with hydrothermal fluids. These observations show that porous and complex PGM textures can also develop through hypogene processes. 

In the Santa Cruz Ni-laterite, the PGE and PGM assemblages found in chromitites record the progressive effects of magmatic, serpentinization-related, and lateritic processes. The primary PGM assemblage reflects a magmatic history broadly comparable to that recorded by the Herbeira chromitites. However, during lateritization, resistant PGM phases were preserved and residually concentrated at the upper part of the lateritic profile. This is accompanied by redistribution of PGE within the lateritic profile, including a positive Pt anomaly in chondrite-normalized PGE patterns observed in a limonite-hosted chromitite, interpreted mainly as the result of residual Pt enrichment rather than direct evidence of supergene PGM neoformation. However, the occurrence of a porous Ir-Fe-Ni-Pt grain enclosed in Fe-oxyhydroxides and characterized by the accumulations of PGE-bearing nanoparticles, show textural similarities to the Pt-Ir-Fe-Ni grains from Falcondo, suggesting that comparable processes, including neoformation (?), may have been involved in the genesis of these grains.

High-resolution observations of the Pt-Ir-Fe-Ni alloys from Falcondo reveal porous textures characterized by aligned nanostructures within a goethite/hematite matrix. These nanostructures occur in bundles with different orientations and form previously undescribed stitching textures, defining parallel and triangular patterns. The alloys exhibit a preferential stoichiometry of (Pt, Ir)_0.26Ni_0.29Fe_0.45 and are absent in pristine chromitites. The grains also contain elongated voids and Pt- and Ir-rich patches. Nanoscale observations show that the grains are compositionally heterogeneous polycrystalline aggregates composed of distinct Fe-Ni-rich, Ir-rich, and Pt-Ir-rich alloy domains, with d-spacings similar to cubic phases. Pt nanoparticles occur within goethite and hematite filling pores, suggesting late-stage Pt mobilization and precipitation in the lateritic environment. To evaluate the different possibilities for their genetic history, these observations were compared with PGM described in the literature from magmatic, hydrothermal-related, and supergene environments. Moreover, the unusual textures of the Pt-Ir-Fe-Ni alloys show textural similarities with Widmannstätten patterns found in Fe-Ni meteorites, without implying any genetic relationship. High-resolution textural and compositional observations of the Pt-Ir-Fe-Ni grains do not provide a definitive conclusion on their genesis but show that they cannot be readily explained by a single genetic process and instead suggest a complex, potentially multistage history involving hypogene precursors and subsequent supergene modification leading to PGM (trans-)formation. High-resolution isotopic and trace-element analyses may provide further constraints on the origin of the Pt-Ir-Fe-Ni alloys and help identify possible biogeochemical fingerprints associated with their formation.

Iron and steel are essential in our day-to-day lives, enabling us to move, interact, work, and play, by being a part of virtually everything that we use on a daily basis. Not only that, the iron and steel industry is also a cornerstone of the Swedish economy and an important player in the export of goods. At the same time, its emission of greenhouse gases and contribution to the enhanced greenhouse effect cannot be overlooked. With a shift towards fossil-free processes and carbon neutrality in the EU as well as globally, ensuring a competitive and future-proof iron and steel industry is more than likely to involve mitigation of harmful emissions from fossil fuels.

A process of particular interest to this thesis is the iron ore pelletizing plant, more specifically a grate-kiln plant. As part of this process, the pellets are indurated inside a large rotating furnace, called a rotary kiln, where they are heated by a coal-fired flame and subjected to temperatures as high as 1200 °C. Secondary process air enters the rotary kiln through two inlet ducts, separated by the so-called back plate. The back plate also houses the fuel nozzle. Inside the rotary kiln, the coal combusts with the secondary air to form a long and stable flame which evenly heats the pellets. To reduce the CO2 emissions formed during the coal combustion, the natural choice is to replace the coal with a sustainable alternative. One such alternative is hydrogen; however the fluid mechanical, combustion, and heat release properties of hydrogen differ greatly from those of coal. A direct replacement of the fuel is difficult, since the mixing of fuel and secondary air dictates the flame properties. The comparatively fast mixing of hydrogen and air gives rise to a flame that is short and intense, negatively affecting the pellet quality. Therefore different means of injecting the hydrogen are needed, to ensure that the resulting flame can imitates the features that characterize the coal flame.

In an attempt to do so, this thesis considers a new way of introducing the hydrogen fuel: using coaxial jets. In this setup, an inner fuel jet is surrounded by an annular outer jet, issuing the same or a different fluid. By adjusting the relative velocities of the inner and outer jets, the shear in the near-jet region is controlled, consequently influencing the mixing of fuel and air. The thesis constitutes examinations of three different models of the rotary kiln: a simplified two-dimensional and a three-dimensional model of the full-scale rotary kiln, as well as a pilot-scale 2D model. The first two models utilize hydrogen as the sole fuel, while the third employs a different methodology which involves the simultaneous use of coal and hydrogen as fuels. All three models are investigated through Computational Fluid Dynamics (CFD) simulations, enabling the otherwise hard-to-measure rotary kiln flow field to be scrutinized. Different configurations of the coaxial jets are compared based mainly on the momentum flow ratio of the outer jet to the inner jet, Mjet.

Non-reacting hot-gas flow simulations of the full-scale 2D model show how the mixing characteristics of the hydrogen jet with the secondary air is affected under a change of the momentum flow ratio. First, hydrogen is issued through both the inner and the outer jet. Lowering Mjet gives longer and narrower jets, thus reducing the mixing rate. This is possible due to the decreased outer jet velocity, reducing the shear with the secondary air. A too value low of Mjet, however, result in recirculation of hydrogen in a wake directly downstream the back plate. Reacting combustion simulations of the same configurations reveal that the jet length is, as expected, correlated to the resulting flame size. Further, the hydrogen recirculation observed in the non-reacting simulations translates to an elevated temperature inside the back plate recirculation zone, likely due to hydrogen combustion in that area. If air is used instead of hydrogen in the outer jet, some different trends are observed. Increasing the momentum flow ratio enables the outer air jet to penetrate further into the rotary kiln, shielding the inner hydrogen jet from the initial mixing with the secondary air. Further downstream, on the other hand, this configuration experiences a higher entrainment rate of the hydrogen jet compared to the case where hydrogen is used in both jets.

The 3D model provides insights into the three-dimensionality of the flow field that cannot be captured by the 2D model. Non-axisymmetric features of the flow field influence how the jet spreads in the vertical and horizontal cross-stream directions. Most importantly, recirculation of hydrogen is observed in the horizontal centreplane, and combustion simulations of this realistic 3D model are needed to determine the effect of this on the flame formation. Additionally, the non-axisymmetric flow field causes the hydrogen jet cross-section to deviate from the circular shape observed in the 2D model, changing the entrainment characteristics of the jet. The principal conclusion from this investigation is that the 3D model is required for reliable predictions of the hydrogen jet evolution. The simplified 2D might, nevertheless, be suitable for initial assessments of the momentum flow ratio's effect on the jet mixing and flame formation.

Lastly, 2D simulations of the pilot-scale rotary kiln uncover some details of the near-jet intricacies of the flow field and mixing. Adjusting the fuel input power ratio of coal to hydrogen—from using only coal to using only hydrogen, to combinations thereof—changes how the different jets interact. A third coaxial jet, providing primary air, seems to outline the fuel jets and dictate their border against the ambient secondary air. The pure coal and pure hydrogen configurations produce the highest and lowest entrainment rates, respectively. Even a small addition of coaxial hydrogen promotes an extended fuel jet, changing how the coal jet mixes with the primary air jet. These results can, together with combustion simulations and experimental measurements of the temperature field and flame shape, be used to determine an appropriate combination of coal and hydrogen that gives the desired heating properties and reduction in CO2 emissions.

This thesis provides results that can be used as a first step in replacing the fossil fuels used in current iron ore pelletizing plants, by showing how hydrogen could be implemented in the rotary kiln induration. It employs simple and effective 2D models, as well as a realistic 3D model, to demonstrate the possibilities of mitigating greenhouse gas emissions from an industry that is, and will likely continue to be, important in the foreseeable future.

Background:Total hip replacement is one of the most successful orthopaedic interventions; however, wearremains a key factor influencing long-term implant performance and survivorship. Additivelymanufactured (AM) PEEK materials have emerged as potential candidates for orthopaedicbearing applications, although their tribological and biological performance under clinically representative conditions remains insufficiently understood.

Aim: The aim of this thesis was to evaluate the tribological and biological performance of AMPEEK materials for orthopaedic bearing applications, focusing on the influence of manufacturing, surface finishing, composite reinforcement, and wear particle isolation and characterisation. In parallel, the thesis investigated the influence of physiologically representative loading profiles on wear behaviour in conventional metal-on-polymer systemsto assess limitations in current preclinical testing approaches.

Methods: This thesis combined a systematic review with experimental evaluation of AM PEEKmaterials and conventional orthopaedic bearing systems. Tribological performance wasassessed using multidirectional pin-on-disc testing under clinically relevant articulationconditions, including evaluation of surface topography, wear behaviour, and wear particlegeneration. A vacuum oven stabilisation approach was developed to improve gravimetric assessment of AM PEEK by reducing the influence of manufacturing-induced porosity onfluid absorption and mass stability.Wear particles were isolated using a phenol-based separation method designed to retain both polyethylene and PEEK particles despite similarities in material and protein density, before characterisation using scanning electron microscopy and in vitro biological assays. Inparallel, physiologically representative loading profiles were applied to conventional metalon-polymer hip systems using full-scale hip simulator testing to investigate their influence on preclinical wear assessment.

Key findings: Surface integrity was identified as a critical determinant of tribological performance in AMPEEK, with manufacturing-induced porosity and surface condition exerting greater influence than surface roughness alone. A vacuum oven stabilisation approach enabled improved gravimetric assessment of AM PEEK by reducing variability associated with fluid uptake and release. A phenol-based isolation method enabled recovery and characterisation of both polyethylene and PEEK wear particles for biological evaluation. AM PEEK demonstrated biological responses comparable to conventional materials, although composite reinforcement did not improve wear or biological performance. Finally, physiologically representative loading increased wear in conventional metal-on-polymer systems relative to standardised conditions, highlighting the importance of clinically representative preclinical evaluation, to prevent underestimation of wear in-situ.

Interpretation: Collectively, the findings indicate that tribological performance of additively manufactured PEEK is governed more strongly by manufacturing- and finish-induced surface integrity thanby surface roughness alone. Physiologically representative loading and multidirection alarticulation substantially influenced wear behaviour, highlighting limitations of simplified preclinical testing approaches and reinforcing the importance of clinically relevant evaluationframeworks. Furthermore, while additively manufactured PEEK demonstrated biological responses comparable to conventional materials, improvements in tribological performance remain important for supporting further biological validation and development of orthopaedic bearing systems.

Conclusions: This thesis demonstrates the importance of clinically relevant tribological evaluation forassessing emerging orthopaedic bearing materials. Physiologically representative loading altered wear behaviour in conventional metal-on-polymer systems, while multidirectional articulation provided greater insight into the tribological performance of additively manufactured PEEK materials.While additively manufactured PEEK demonstrated biological responses comparable toconventional materials, tribological performance remained strongly dependent on manufacturing- and finish-induced surface integrity and was not improved through theintroduction of composite reinforcement. Overall, the findings support continued investigation of additively manufactured PEEK as a candidate orthopaedic bearing material, while highlighting the need for further optimisationof manufacturing processes and more clinically representative evaluation methodologies prior to translation.

Background: Neck pain is one of the most common musculoskeletal disorders worldwide and is frequently associated with impairments in sensorimotor control. Identifying such impairments may be important for guiding targeted rehabilitation and evaluating treatment outcomes. However, objective assessment of cervical sensorimotor functions often requires specialized equipment, highlighting the need for accessible, valid, and reliable assessment methods. Recent advances in virtual reality (VR) provide new opportunities for both assessment and rehabilitation of cervical sensorimotor functions, potentially in remote or home-based settings.

Aim: To evaluate the measurement properties of newly developed VR-based assessments of cervical sensorimotor functions in individuals with and without neck pain, and to investigate the feasibility of a home-based VR sensorimotor intervention for individuals with chronic neck pain.

Methods: This thesis comprises five quantitative studies: four cross-sectional studies of measurement properties and a feasibility randomized controlled trial. Studies I and II evaluated the concurrent validity of VR-based assessments of joint position sense (JPS), cervical reaction acuity (CRA), range of motion (ROM), and fast cervical rotation in 20 participants with and without neck pain. Agreement between the VR-based measures and a reference measurement system was evaluated using Bland–Altman analysis and intraclass correlation coefficients (ICCs). Study III investigated the test–retest reliability and discriminant validity of the CRA test in individuals with chronic traumatic neck pain (CTNP; n = 42) and asymptomatic controls (CON; n = 38). Reliability was assessed using ICCs and the standard error of measurement (SEM), while group differences were examined using analysis of covariance. Study IV used orthogonal projections to latent structures (OPLS) to evaluate the ability of a VR-based test battery comprising assessments of movement sense, JPS, CRA, ROM, and postural sway, to discriminate between participants with CTNP (n = 55) and CON (n = 48). In Studies III and IV, construct validity was assessed by examining associations between VR-based test outcomes and patient-reported outcome measures using correlation analyses and OPLS regression models. Study V evaluated the feasibility of home-based VR sensorimotor training compared with conventional neuromuscular endurance training in individuals with chronic neck pain, and explored physiotherapists’ experiences of delivering the interventions.

Results: The VR-based tests demonstrated acceptable concurrent validity, with generally small measurement biases and moderate to excellent agreement with the reference system for cervical ROM, movement velocity, and the CRA test. Agreement was poorer for JPS and at very high movement velocities. The CRA test demonstrated acceptable test–retest reliability and discriminant validity, except for the variable reaction time which showed weaker measurement properties. From the CRA outcome measures, peak velocity had the strongest ability to discriminate between groups. The multivariate test battery differentiated participants with CTNP from asymptomatic controls and explained approximately 34% of the variation in group membership. Compared with controls, participants with CTNP demonstrated impaired movement sense, reduced movement smoothness and velocity, longer task-completion times, reduced ROM, and greater postural sway. Associations between VR outcomes and patient-reported outcomes were generally low. In Study V, prolonged recruitment was identified. The intervention completion rate was 92% in the VR group and met the predefined feasibility criterion. Adherence and outcome-measure completion rates were high in both groups. Dizziness was reported more frequently in the VR group, whereas neck pain was reported more frequently in the NET group; symptoms of simulator sickness were generally mild. Physiotherapists viewed the delivery of the intervention positively but identified the need for technical support, cost, and required technical skills as potential barriers.

Conclusions: VR-based assessment shows promise as an objective and accessible approach to identifying impairments in cervical sensorimotor function. A future full-scale RCT appears feasible in most respects, provided that challenges related to recruitment and technical support are addressed. Further research should explore patients’ experiences and identify barriers and facilitators to clinical implementation.

Railway infrastructure is a critical component of sustainable transportation systems. However, the linear and rigid nature of railway networks makes them highly vulnerable to climate hazards. Moreover, the growing frequency and intensity of climate hazards driven by climate change increase the risks of climate-related failure modes (CRFMs). Despite this growing concern, understanding of CRFMs, their associated risks, and effective adaptation strategies remains limited. This thesis aims to bridge these gaps by conducting extensive analyses of Swedish railway maintenance dataset, supported by a comprehensive literature review. 

To achieve the thesis objectives, a systematic literature review was first conducted to identify climate hazards and associated CRFMs, irrespective of their intensity, likelihood, or geographical variation. The review provides a comprehensive inventory of climate hazards and CRFMs, offers a structured classification framework, and highlights hazard–failure relationships as well as cascading and compound effects of failures. Furthermore, the proposed adaptation measures were reviewed and categorized into physical, operational, ecological, institutional, and behavioural strategies. Key implementation challenges and potential risks of maladaptation were also discussed. In this context, quantitative risk assessment and the use of predictive models were identified as key institutional and operational strategies, respectively, for effective climate adaptation planning.

Building on these insights, the empirical core of this thesis focuses on assessing the risk of CRFMs and developing predictive tools for the Swedish railway infrastructure. To this end, CRFMs were identified through text mining of historical corrective maintenance data covering all five maintenance regions in Sweden. A probabilistic model was developed to quantify the risk of identified CRFMs, considering both maintenance-related and operational consequences. Risk distributions were subsequently estimated using Monte Carlo simulation. The results enable the prioritization of CRFMs at the national scale and a comparative assessment of regional vulnerability across Sweden. 

Finally, a machine learning framework was developed to distinguish between climate-related and non-climatic failure modes by integrating the failure records with meteorological data. The performance of several machine learning algorithms was evaluated across different time horizons prior to failure events. In addition, the analysis identified key climatic variables that significantly influence model performance and failure classification.

Overall, this thesis provides a fundamental basis and practical evidence to support planning for climate-resilient railway infrastructure. Although the empirical analyses focus on the Swedish railway network, the proposed approaches are transferable and can be applied to other railway systems.

This thesis has two interconnected aims: to develop geophysical modelling and inversion methods, and to apply them to mineral exploration through case studies from Norrbotten, Sweden. Mineral exploration increasingly targets deposits at greater depth, where surface observations alone do not constrain subsurface structure. Integrated geoscientific investigations, and geophysical methods in particular, are then one of the few ways to obtain information on physical properties at depth.

The five case studies comprise magnetotelluric, controlled-source electromagnetic, magnetic, and gravity methods, interpreted together with other geoscientific information, most commonly geological and petrophysical. The methodological work centres on the MR3DMod modelling and inversion framework developed for multi-resolution grids. In this thesis the framework was extensively used for electromagnetic data and further developed for 3-D inversion of potential-field data. Three studies, carried out in collaboration with LKAB, investigate iron mineralisation in active mining districts. The remaining two address regional exploration and an electromagnetic exploration workflow focused on a poorly characterised electrical-conductivity anomaly.

The studies present several 3-D geophysical models at local and regional scales and demonstrate their use in geological interpretation and mineral exploration. A central methodological contribution is a robust inversion scheme based on the Huber loss function and implemented through iteratively reweighted least squares. Applied to all magnetotelluric studies, it reduces the influence of observations that cannot be fitted consistently by standard inversion, providing a more quantitative complement to manual data selection and reducing the need to apply substantial error floors. The thesis also shows the value of integrating multiple geophysical models with petrophysical and geological information and presents a clustering approach to support that integration.

Beyond the individual case studies, the thesis identifies two mineral-prospectivity signatures. First, paired extreme positive and negative magnetic-susceptibility contrasts in 3-D models can form a recognisable signature of magnetic, commonly iron-rich, mineralisation. Although the negative contrasts may reflect inversion artefacts from the limitations of smooth inversion and unmodelled magnetic remanence, the physical volumes that produce such artefacts remain of prospectivity interest. Second, regional crustal-scale conductive anomalies can be refined by local magnetotelluric surveys into testable exploration targets. 

Taken together, the results demonstrate a practical multi-scale workflow: regional geophysical models identify prospective structures, and targeted local surveys resolve their 3-D geometry and exploration relevance. By combining improved inversion methods with geological and petrophysical information, 3-D geophysical models can strengthen geological understanding and support more focused mineral exploration workflows.

This thesis investigates sound perception and sound-quality evaluation in electric trucks, focusing on the relationship between objective acoustic metrics and human perception.

The work addresses two main challenges: understanding the perception of complex tonal sounds and identifying the role of functional sound feedback in electric vehicles. Through listening tests, thematic analyses, simulator studies, and comparisons of established tonality metrics, the research demonstrates that the perception of tonal content depends on interactions between multiple tonal components and auditory processing mechanisms.

The findings further show that functional sound feedback can influence driver experience and physiological responses. Several existing tonality metrics correspond well with subjective evaluations.

This dissertation investigates how linguistic complexity (lexical and grammatical), linguistic accuracy, and cohesive devices relate to the grading of written learner texts in the Swedish National Test of English (NTE), a high-stakes exam in upper secondary school. The NTE is taken in English 5 (B1.2), which is required for an upper secondary degree, and English 6 (B2.1), which is required for university admission. For both courses, the curriculum expects students to write texts characterised by "correctness […] variation and complexity" that are adapted to situation, recipient, and purpose. The NTE is meant to ensure that grades reflect students' knowledge of English in a fair and reliable way, and since the test result strongly influences the course grade, it is important that the test is constructed and applied in a scientifically sound manner.

Teachers assess the written part with instructions that include graded example texts, marked by expert raters on behalf of the Swedish National Agency for Education, which serve as benchmarks for each grade. The instructions point to textual qualities such as spelling, vocabulary, cohesive devices, grammatical structures, and idiomaticity, and indicate that higher-graded texts should be more complex than lower-graded ones. Whether teachers' grading agrees with these benchmarks and instructions has not previously been studied in this context.

The aim of this five-article compilation thesis is therefore to examine the relationships between linguistic complexity (lexical and grammatical), linguistic accuracy, and cohesive devices and grades in the written part of the NTE. A corpus of 142 graded example texts and 175 teacher-graded texts has been compiled and analysed with, for example, TAALED, TAALES, the Lexicogrammatical Tagger, and the UCLouvain Error Editor (version 2). The linguistic analysis is followed by statistical analyses in R, including ordinal regression with interactions, Spearman's correlations, and 95% confidence intervals.

The findings reveal discrepancies between the graded example texts, the teacher-graded texts, and the assessment instructions. For example, lexical complexity has a stronger effect on grade in the graded example texts than in the teacher-graded texts in English 5. Linguistic accuracy affects grades in both sets of texts, although the instructions treat it as less important than other constructs. Grammatical complexity barely affects grades in either set, despite being described as important in the instructions. These results are discussed in relation to curriculum and test construction, communicative language teaching, and teacher education.

Deposit formation — also referred to in this thesis as slagging — remains one of the main operational challenges in grate-kiln iron ore pelletizing. In these systems, process heat is supplied by combusting pulverized fuel — conventionally coal powder — which is injected and burned in the rotary kiln; the resulting hot, ash-laden flue gas then passes through the rotary-kiln inlet and the transfer chute on its way to the grate. It is in these hot, strongly oxidizing regions — chiefly the rotary-kiln inlet and the transfer chute, at approximately 1100–1250 °C and ≈ 16 vol.% O₂ — that the fuel-derived ash species interact with disintegrated iron ore pellet dust and accumulate on the refractory walls; the findings of this thesis are correspondingly restricted to, and valid for, these regions. The resulting deposits disturb the flow of gas and pellets, reduce process stability, and contribute to refractory wear and production losses. Despite their industrial importance, the mechanisms governing these deposits remain insufficiently understood. This thesis addresses that gap by combining pilot-scale and full-scale observations with thermochemical equilibrium calculations and viscosity-based interpretation, with the overarching aim of clarifying the role of pellet dust, establishing a deposit (slag) formation scheme, developing predictive tools, and evaluating alternative fuels. The experimental work is centered on a 0.4 MW pilot-scale Experimental Combustion Furnace (ECF), complemented by observations from a full-scale industrial grate-kiln.

The role of the disintegrated iron ore pellet dust was examined first. Particle sampling and deposit characterization showed that pellet-dust addition shifts the particulate system from bimodal to trimodal, with the strongest interaction in the coarse fraction, where coal ash adheres to hematite-rich particles. Pellet dust alone exhibited a relatively low slagging tendency; however, its interaction with coal ash produced denser, more strongly sintered and harder deposits, most pronounced in the transfer-chute region. Pellet dust, therefore, acts not as an independent slagging agent but as a reactive, Fe-rich component that becomes critical when combined with coal ash.

On this basis, a systematic deposit formation scheme was established from the combined pilot- and full-scale data. The scheme attributes deposit formation (slagging) to a coupled sequence of ash transport, ash chemistry, and pellet-dust interaction, in which hematite dissolves into a Ca-rich aluminosilicate melt. This produces a dual effect — increased melt formation together with reduced melt viscosity — that intensifies at elevated temperatures and is further promoted under locally reducing conditions through the reduction of Fe³⁺ to Fe²⁺.

To enable prediction, theoretical tools were developed to characterize deposit formation (slagging) tendency from ash composition and process conditions. Ash composition was found to strongly govern deposit formation, with coals rich in fluxing agents (CaO, MgO, K₂O, Na₂O, and Fe-bearing species) being more prone to forming low-viscosity melts and sintered deposits. A Qualitative Slagging Indicator (QSI), which captures the effect of ash chemistry alone, and an Absolute Deposition Tendency (ADT), which additionally accounts for the ash flow entering the furnace, were formulated identifying melt viscosity as a key descriptor of deposit formation (slagging) severity.

Finally, the predictive tools (QSI and ADT) were applied together with the pilot-scale co-firing results to evaluate the feasibility of co-firing or replacing coal with renewable biomass. Co-firing coal with woody biomass can promote low-viscosity molten phases through the addition of Ca and K, although under certain conditions, high-melting alkali-bearing solids form and partly alleviate slagging. Fifteen renewable candidates were assessed: five Nordic raw biomasses — stem wood, bark, forest residues, willow and reed canary grass — together with the fast-pyrolysis oil and the biochar produced from each of them. Among these, the pyrolysis oils emerged as the most promising with respect to deposit formation in the transfer chute.

Collectively, the thesis demonstrates that deposit formation (slagging) at the rotary-kiln inlet and in the transfer chute of grate-kiln iron ore pelletizing plants is governed by the coupled effects of ash transport, ash chemistry, pellet-dust interaction, melt formation, and melt viscosity. It establishes a coherent deposit formation (slagging) pathway, identifies melt viscosity as a key descriptor of deposit formation (slagging) severity, and provides a practical framework for fuel screening. These findings advance the mechanistic understanding of deposit formation in industrial pelletizing plants and offer a basis for more informed fuel selection and future slagging-mitigation strategies.

Keywords: Iron ore pelletizing; deposit formation, slagging; ash transformation; pellet dust; coal combustion; biomass co-firing; thermochemical equilibrium calculations; melt viscosity; Qualitative Slagging Indicator (QSI).

Developing students’ conceptual understanding remains a persistent challenge in physics education, where instruction has traditionally emphasized procedural problem-solving and mathematical formalism. Despite extensive evidence from physics education research demonstrating the effectiveness of conceptual instruction for promoting meaningful learning, such approaches remain unevenly implemented in secondary school practice. This thesis investigates how conceptual physics instruction can be understood, enacted, and sustained in Swedish upper secondary education, with particular attention to teacher experience, instructional design, student learning outcomes, and equity.

The thesis comprises four empirical studies conducted between 2022 and 2024, employing a mixed-methods research design that integrates qualitative case studies, quasi-experimental methods, and collaborative action research. Across the studies, data were collected from four physics teachers with varying levels of experience and over 800 students, using interviews, surveys, classroom observations, instructional artefacts, written examinations, and the Gender-Force Concept Inventory (G-FCI). The analytical framework draws on pedagogical content knowledge (PCK), conceptual change theory, variation theory, constructivist learning theory, and equity-oriented perspectives in physics education.

The findings demonstrate that conceptual physics instruction supports deeper conceptual understanding and student engagement, particularly when implemented consistently across courses. Results further indicate that teacher experience and well-developed PCK play a critical role in the successful enactment of conceptual teaching, influencing classroom discourse, diagnostic sensitivity, and the balance between conceptual and procedural learning goals. Importantly, sustained conceptual instruction was found to reduce—and in some cases reverse—gender disparities in students’ conceptual understanding of Newtonian mechanics, highlighting its potential as an equity-oriented pedagogical approach.

Beyond documenting instructional effects, the thesis advances a teacher-centred perspective on implementation. Through collaborative action research, teachers articulated concrete strategies and organizational conditions required to make conceptual instruction manageable and sustainable, including structured lesson formats, diagnostic tools, peer collaboration, and long-term professional learning communities. These insights are synthesized into a teacher-informed didactic proposal that conceptualizes physics instruction as a situated practice shaped by interacting dimensions of teacher conceptions, contextual constraints, instructional goals, classroom strategies, and enabling conditions.

Overall, the thesis contributes to physics education research by bridging the gap between established evidence on conceptual learning and the realities of classroom implementation. It offers empirically grounded insights relevant to teacher education, curriculum development, and educational policy, and positions conceptual physics instruction as both a pedagogical and systemic endeavour essential for fostering meaningful and equitable physics learning.