Multiscale integrated modeling of the Iron Oxide-Apatite Mineral System in Northern Norrbotten, Sweden

The subsurface has long supplied raw materials, yet with most giant surface-exposed deposits already discovered, exploration increasingly focuses on deeply buried mineral systems in frontier terrains. Collaborations across and beyond traditional geoscience disciplines are becoming increasingly important as deeper discoveries require multidisciplinary and integrated exploration tools. These multidisciplinary exploration tools aim to integrate the mineral system paradigm with existing geological and geophysical models and interrogate and characterize the spatial and temporal relationships of its components. This doctoral thesis employs geological modeling and integration with existing geophysical models within a multiscale framework to investigate the expression of the iron oxide-apatite mineral system in northern Norrbotten (Sweden). The region is regarded as a major metallogenic province hosting more than 40 iron oxide-apatite (IOA) deposits, including the giant Kiirunavaara deposit. More than a century of mining, exploration, and geological surveying in the area has led to an outstanding repository of geoscientific data, encompassing geological mapping, large drill core archives, and high resolution geophysical dataset, providing a solid foundation for integrated, multiscale modeling of the mineral system. At the deposit scale within the Kiruna mining district, integration of surface and drill-core structural measurements with geotechnical, structural, and lithological logging results in models that highlight how the interplay between ore-parallel and orthogonal structures controls mineralization. Low rock quality designation (RQD) values and coreorientation data systematically indicate weak rock mass at ore contacts, whereas orthogonal conjugate faults accommodated heterogeneous strain across adjacent blocks. Within the district, petrophysical measurements of major stratigraphic units establish diagnostic contrasts but also reveal pronounced intraformational variability controlled by alteration intensity and fabric development. Although stratigraphic formations can be discriminated geophysically, this heterogeneity complicates direct local-scale interpretations. The dataset provides a calibrated petrophysical reference, linking field-based geological observations and measurements with ground and airborne geophysical surveys. At the province scale, an integrated 3D model synthesizing deposit- and district-scale geological models with province- wide lithological and structural models and inversions of magnetic and gravity surveys constrain the crustal architecture of the northern Norrbotten ore province (NNOP; here defined as the area between Gällivare and Kiruna). Mafic-ultramafic intrusions occur as dense, magnetically heterogeneous domains systematically proximal to vertically extensive conductors imaged by magnetotellurics (MT), interpreted as the upper-crustal expression of transcrustal magmatic-hydrothermal conduits. IOA deposits are typically situated along second-order oblique structures that intersect or splay from major shear zones at the margin of dense and magnetic bodies, rather than within the firstorder shear zones themselves or directly coincident with MT conductors. Across deposits and prospects, diagnostic total magnetic intensity (TMI) responses, characterized by steep gradients with localized highs flanked by negative lobes constitute repeatable proximal indicators of IOA mineralization. The magmatic character of the intrusions is further constrained by petrography, whole-rock geochemistry, petrophysical characterization, and SIMS U-Pb zircon and titanite geochronology of mafic to intermediate intrusions. Two intrusive groups are distinguished, a cumulate set marked by olivine-pyroxene-plagioclase-rich assemblages, positive Eu/Eu*, elevated Sr/Yb, high density (>3.0 g/cm3) and variable magnetic susceptibilities, and another melt-proxy set of non-cumulates further subdivided into calc-alkaline and tholeiitic lineages with lower densities (2.84-3.00 g/cm3) and more uniform susceptibilities. Cumulate intrusions coincide with MT conductors, gravity highs, and concentric magnetic anomalies, supporting their interpretation as upper-crustal expressions of a deeper magmatic feeder zone. Their association with IOA deposits and complementary geochemical signatures indicates that early Svecokarelian intrusions supplied heat and likely magmatic input to the mineral system. Zircon U-Pb data place both cumulate and non-cumulate intrusions within the early Svecokarelian magmatic pulse, while titanite U-Pb results record both near-magmatic crystallization and later tectonothermal resetting events. At multiple scales, the analyses converge to show that IOA mineral systems in northern Norrbotten emerged from a dynamic interplay of magmatism, structural, and subsequent tectonothermal processes, recorded from deposit scale to province-wide crustal architecture. Embedding field-based geological observations and supporting analysis, mineral system concepts, and geophysical inversion results into integrated multiscale modeling, this thesis establishes a systematic link across scales and a coherent basis for interrogating the spatial and temporal organization of mineral system components. While the approach inevitably simplifies the complexity of a long-lived Paleoproterozoic terrain, it underscores the value of integrated geological modeling in reconciling diverse datasets into consistent frameworks. In doing so, the study refines current interpretations of IOA mineralization in northern Norrbotten and contributes to a more rigorous geological understanding of this major metallogenic province

Ash transformation during thermochemical conversion of agricultural biomass in entrained flow conditions with a focus on Si and P

Agricultural biomass is increasingly acknowledged as a versatile renewable feedstock in the energy conversion units. However, the efficient utilization of agricultural biomass in thermochemical processes could be hindered by the relatively high ash content compared to woody biomass. These types of biomasses often contain a relatively high share of silicon (Si) and phosphorus (P). The presence of these elements in the biomass can contribute to ash-related operational challenges such as slagging, fine particle emissions, and deposit formation. Beyond these challenges, the recovery of Si- and P-containing compounds as by-products during thermochemical conversion presents an opportunity to generate additional value, thereby improving the overall resource efficiency and economic viability of using agricultural biomass as a feedstock. Despite the importance of Si and P, the detailed ash transformation processes during entrained flow conversion of such biomass assortments remain inadequately understood. This knowledge is crucial for reducing or eliminating ash-related issues while unlocking pathways for recovering valuable Si- and P-containing compounds during entrained flow conversion of agricultural biomass.  The main objectives of this work were, therefore, to 1) determine the ash transformation pathways of Si during entrained flow combustion of different types of Si- and P-rich agricultural biomass, 2) determine the ash transformation pathways of P during entrained flow combustion of different types of Si- and P-rich agricultural biomass, and 3) investigate the potential of extracting valuable Si- and P- containing compounds from the gas phase and/or residual ashes formed during entrained flow conversion of different agricultural biomass.  The study combines lab-scale experiments in a laminar drop tube furnace (DTF) at 1200 °C and 1450 °C in combustion conditions (using air) and in pyrolysis conditions (using N2), with pilot-scale combustion experiments in a 150-kW powder burner connected to a horizontal ceramic-lined furnace. Three agricultural biomass types were selected to represent a range of Si and P concentrations in the selected fuels: rice husks representing Si-rich husks from certain cereal crops like rice and oat (i.e., Si-rich fuel with minor amounts of K, Ca, Mg, and P), grass representing Si- and K-rich herbaceous energy crops from grasses and residues from certain agricultural crops such as wheat straw and other cereal straws (i.e., K-Si-rich fuels with moderate amounts of Ca, Mg, and P), and brewer’s spent grains (BSG) representing P-rich grain- and seed-based agricultural biomass (i.e., P-rich fuels with a relatively high share of Si with moderate to minor Ca, Mg, and K content). All three fuels were investigated in the lab-scale DTF, whereas rice husks and BSG were examined in a 150-kW powder burner. The produced residual materials, i.e., coarse ash fractions (> 1 µm), fine particle fractions (i.e., PM1, <1 µm), chars, and deposits were morphologically and chemically characterized using SEM-EDS, XRD, ICP-AES, IC, and CHN-analysis. Thermodynamic equilibrium calculations (TECs) were employed to interpret experimental findings and theoretically assess ash transformation pathways. Across all investigated fuels and combustion scales, Si was predominantly retained in the coarse ash fractions (>1 µm), indicating limited volatilization under the studied conditions. During the combustion of rice husks under both scales, Si present in the outer surface of the fuel formed skeleton-like coarse ash particles. Meanwhile, the Si present in the inner part of the fuel interacted with minor ash-forming elements (i.e., K, Ca, Mg, and P) and formed Si-rich molten spheres. Overall, the resulting coarse ash fractions were comprised of amorphous non-molten Si-rich particles, Si-rich melt with moderate to minor amounts of K, Ca, Mg, and P, and crystalline SiO2 (cristobalite). For grass, the results from the combustion experiments conducted under DTF conditions showed that the fuel inherent Si initially reacted with K to form molten K-silicates. The subsequent incorporation of Ca, Mg, and P into molten K-silicates led to the formation of K-Ca-Mg-rich phosphosilicate melt in the residual coarse ash fractions. Si was found in the residual coarse ash fractions mainly as amorphous K-Ca-Mg-rich phosphosilicate melt and crystalline SiO2 (quartz), Ca2MgSi2O7, CaSiO4, KCaSi3O9, Ca7(SiO4)2(PO4)2, and Ca5(SiO4)(PO4)2. For the BSG, the experiments conducted at both scales showed that the fuel inherent Si initially interacted with partially molten Ca-Mg-phosphates, and formed Ca-Mg-rich phosphosilicate melt. Si in the residual coarse ash fractions was identified as amorphous Ca-Mg-phosphosilicate and crystalline SiO2 (i.e., quartz and/or cristobalite).  For all investigated fuels and conditions, P was primarily retained in the coarse ash fractions (> 1 µm) mainly in the form of orthophosphate compounds. A minor to moderate amounts of fuel inherent P identified in the fine particle (i.e., PM1, <1 µm) ash fractions, indicating partial volatilization of P during the investigated conditions. During combustion of rice husks across both scales, P was primarily retained in the residual coarse ash fractions and incorporated into Si-rich molten spheres with moderate to minor amounts of K, Ca, Mg, and P. Additionally, a moderate (≈ 20%)  to high (≈ 40%) share of P was detected in the PM1 fractions under studied combustion conditions. For grass fuel, DTF experiments showed that fuel-inherent P, together with Ca and Mg, interacted with molten K-silicates and formed K-Ca-Mg-rich phosphosilicate melt. P in the residual coarse ash fractions was found as K-Ca-Mg-rich phosphosilicate melt and crystalline Ca7(SiO4)2(PO4)2, Ca5(SiO4)(PO4)2, Ca5(PO4)3(OH), Ca2.89Mg0.1(PO4)2, and Ca9MgKPO4.  Furthermore, a minor (≈ 5%) to moderate (≈ 35%) amount of P was identified in the PM1 fractions at 1200 °C and 1450 °C, respectively. For BSG, the fuel inherent P (i.e., phytates) decomposed to partially molten Ca-Mg-phosphates, which subsequently interacted with Si-rich particles, leading to the formation of a Ca-Mg-rich phosphosilicate melt. In both DTF and powder burner experiments, P in the residual coarse ash fractions was primarily retained as amorphous Ca-Mg-phosphosilicate melt and crystalline Ca3Mg3(PO4)4. A minor (≈8%) to moderate (≈23%) share of P was also detected in the PM1 fractions under the investigated combustion conditions. The combined results from TECs and experimental studies demonstrated the fuel-specific potential for recovering valuable Si- and P-containing compounds from gas and/or residual coarse ashes (>1 µm) during entrained flow conversion of different types of agricultural biomasses. For rice husks, TECs indicated that extracting valuable Si-containing compounds (e.g., SiC (s)) from the gas phase would require very high temperatures inside the flame (i.e., around 2000 °C) to volatilize a moderate amount of fuel inherent Si. Furthermore, it would require an inert cooling atmosphere and elevated surface temperatures around 1500 °C to form potentially valuable Si-containing compounds, which is challenging to achieve in practice. However, both lab- and pilot-scale combustion experiments showed the potential to extract relatively pure silica from the residual coarse ash fractions collected after entrained flow combustion of rice husks. In the case of grass, TECs did not indicate the possibility of forming valuable Si- and/or P-containing compounds from the gas phase. Regarding BSG fuel, TECs suggest that the surplus of P to Si and cations in the fuel can facilitate formation of valuable H3PO4 from the gas phase at lower surface temperatures (i.e.,< 400 °C). Moreover, the coarse ash fractions obtained during the combustion experiments of grass and BSG primarily contained different phosphosilicate melts. Further assessment is required to determine the plant availability of P in such melts

Hydrogen Embrittlement in Rolling Element Bearings

With the global increase of hydrogen applications and industries comes an increase in the demands for the hydrogen infrastructure, where reliability is essential. Compressors are an important part of the hydrogen infrastructure, with rolling element bearings being a key component. However, hydrogen is known to significantly reduce the mechanical properties of rolling element bearings, a phenomenon called hydrogen embrittlement. Studies report that bearings which are subjected to hydrogen can fail up to ten times faster compared to bearings operating in other conditions. This detrimental effect on bearing performance has led to research within the subject of hydrogen embrittlement in bearing steels. While it is well established in research that hydrogen affects bearings negatively, several research challenges remain. This includes both the fundamental level to further understand the interaction of hydrogen with the steel as well on a more applied level when it comes to the quantification of hydrogen damage, as most of the research available in hydrogen embrittlement has a qualitative character.  In this research, rolling sliding tribotesting using a micropitting rig (MPR) as well as full bearing testing were performed to further understand the interaction between hydrogen and bearing steel. These tribotests were combined with electrochemical hydrogen charging, thermal desorption mass spectrometry (TDMS) as well as extended material analysis to connect the wear to the hydrogen concentration as well as hydrogen trapping state in the bearing steel. The hydrogen trapping state in the material is of importance, as a lower hydrogen trapping energy is often correlated with a higher potential of hydrogen embrittlement. The results have shown that the cyclic straining of bearing steel during tribotesting can lower the hydrogen trapping energy, highlighting the increased embrittling effect of hydrogen in bearing applications. Another finding was a quantitative correlation between diffusible hydrogen concentration of bearing steel and surface-initiated damage. The hydrogen concentration of bearing steel was systematically varied by different hydrogen pre-charging conditions, which was then followed by tribotesting and wear quantification. Results revealed that at a hydrogen concentration between 1.4-2 wppm, the wear quantity doubled, while the wear mechanisms remained the same. A novel in situ hydrogen charging full thrust bearing test rig, the Hydrogen Embrittlement in Rolling Element Bearings (HERo) rig, has been developed. This test rig offers several advantages compared to test setups previously described in the literature. As a result of in situ charging, the diffusible hydrogen concentration during tribotesting is not decreasing as in conventional setups where pre-charging is performed prior to tribotesting. This allows for a more precise measurement of the influence of hydrogen on bearing steel. Furthermore, the charging in the HERo rig is performed via the backside of the bearing washer, meaning that the electrolyte is never in contact with the wear track, preventing corrosion or alteration of the surface roughness. The experiments performed with the HERo test rig show a significant decrease in bearing runtime under the influence of hydrogen by a factor of 3. While tests without hydrogen charging failed due to lubricant degradation and surface-initiated wear, hydrogen charged tests failed due to sub-surface initiated macropitting with the presence of white etching cracks. When varying hydrogen pre-charging and in situ charging procedures, it was found that longer pre-charging led to earlier bearing fatigue, while the damage mechanism stayed identical for the different hydrogen concentrations. This indicates that a critical hydrogen concentration exists not only for surface-initiated wear as mentioned above, but also for the initiation of sub-surface crack networks and macropitting. Lastly, it was found that hydrogen promoted not only the formation of white etching cracks and white etching areas, but also martensitic decay and formation of dark etching areas.  In summary, results of the project confirm the detrimental effect of hydrogen on bearing steel, and add quantitative data to the state of knowledge, making it possible to industrially use the research data for more reliable bearings in hydrogen environments.

A Penny for the Environment : Perceptions, Signalling and Bias in Crowdfunding

This doctoral thesis consists of an introductory preface and four independent papers, addressing and examining different aspects of crowdfunding. The papers focus on the role of perceptions, signalling and gender effects in influencing the outcomes for environmentally oriented crowdfunding initiatives. Paper 1 investigates how an average backer's perceptions of a crowdfunding project's environmental characteristics impact funding outcomes. The empirical analysis is based on data from 406 projects, and four individuals' independent assessments of each project's degree of different environmental characteristics. There is partial evidence that projects perceived as environmentally beneficial are more successful than others in securing funding. However, evidence shows that signalling a project as environmentally beneficial negatively affects crowdfunding outcomes, regardless of whether the project is perceived as genuinely environmentally beneficial or as using greenwashing tactics. Thus, project owners ought to be cautious with making environmental claims to market their projects. In Paper 2, voluntary crowdfunding donations are used as a payment vehicle to examine the attitudes for restoring the aurochs, an extinct keystone species. By reintroducing the aurochs, some ecosystem services could be restored. However, de-extinction could be viewed as "unnatural" by the general public, potentially harmful for the legitimacy of conservation policy. The paper investigates whether attitudes towards restoring the aurochs are dependent on the de-extinction technique: breeding or gene editing. The empirical data are based on a split-sample contingent valuation survey of over 2000 individuals, and the findings indicate that while the de-extinction technique does not affect crowdfunding donations on average, women are more reluctant than men to donate to the project if it employs a gene-editing technology. Additionally, the results indicate large heterogeneity in willingness to pay; however, in general, higher willingness to pay is found amongst younger individuals and within members of environmental organisations. Paper 3 focuses on gender effects in donation crowdfunding for an environmentally oriented initiative. Specifically, the study investigates potential gender bias against the project owner, as well as gender differences amongst backers. The results are based on a split-sample contingent valuation survey of over 1600 respondents, where half of the respondents were presented with a male project owner, and the other half was presented with a female project owner. The results suggest there is no gender bias in funding decisions: both project owners were equally likely to secure funding for their initiatives. Additionally, there was little evidence of gender differences between respondents. Instead, other respondent and project characteristics, such as age, latent environmental attitudes and requested donation amount, affect the decision to contribute to the environmental crowdfunding project. Paper 4 also investigates gender biases against the project owner, however, in a lending crowdfunding setting. The study employs a split-sample choice experiment, presenting an energy technology demonstration project. While such projects are generally led by men, the split-sample survey allows for alternating the gender of the project owner. The study investigates whether risk signals and project attributes are interpreted differently based on the gender of the entrepreneur. The results are based on responses from 2000 individuals, and indicate little evidence of gender bias. However, male respondents are more likely to invest in a project in which a female project owner has established a network to collaborate with, but are also more negative towards a project with a female leader who has no such collaboration.Individuellt engagemang och teknologisk utveckling: gräsrotsfinansieringens roll i övergången till ett fossilfritt samhälleAttityder till användande av bioteknik för återställande av artbestån

Modeling and Analysis of Rotorcraft Airfoil Aerodynamics Under Martian Atmospheric Conditions

Throughout history, human curiosity and the desire to explore have driven advancements in engineering capabilities and technologies. These efforts have extended our reach beyond Earth, with Mars emerging as one of the most important targets for planetary exploration. While rovers and landers have traditionally been used to study planetary surfaces, rotorcraft and other aerial vehicles have recently shown great promise for exploring the Red Planet. Such vehicles can access diverse terrains that are difficult or impossible for conventional landers and rovers to reach. However, the unique characteristics of the Martian atmosphere present significant aerodynamic challenges that must be overcome to enable sustained and efficient flight. Successful operation under these conditions requires a deep understanding of low Reynolds number aerodynamics, due to the rarefied atmosphere, and the influence of environmental factors such as pervasive Martian dust. The combination of low Reynolds number flows and suspended dust particles creates unique challenges for rotorcraft aerodynamics on Mars. This thesis investigates these challenges through Computational Fluid Dynamics (CFD) simulations, focusing on the performance of a cambered plate airfoil with 6% camber and 1% thickness, which is well suited to the Martian environment. The research addresses both fundamental aerodynamic phenomena and environmental effects, providing insights into model selection for accurate flow prediction, sensitivity of performance to Reynolds number variations, and the long-term impact of dust accumulation on airfoil behavior. This work presents a comprehensive overview of the evolution of drone designs for planetary exploration, emphasizing the main aerodynamic and control challenges involved. Operating in planetary atmospheres introduces unique difficulties, particularly due to the low chord-based Reynolds numbers and the presence of floating dust particles that can affect both aerodynamics and system reliability. The aerodynamic behavior at Reynolds numbers on the order of 104 is investigated, focusing on the effect of increasing the rotor or chord dimension. Results show that increasing the Reynolds number from 20,000 to 50,000 does not significantly improve performance, as the formation of Laminar Separation Bubbles (LSBs) on the surface still occurs. The transition model used, γ–Reθ, is able to accurately capture bubble formation. However, its limitations are also identified through comparison with other models, among which  γ–Reθ is found to be the most reliable transition RANS model for these flows, since k-kL-ω fails to reproduce the correct post-stall behavior. Unsteady Navier–Stokes (UNS) simulations exhibit the same inability due to the absence of turbulence modeling; however, their lower computational cost makes them suitable for preliminary studies and acceptable for low angles of attack. The accumulation of dust particles on the airfoil surface is also examined, showing that particle deposition alters the airfoil geometry and leads to measurable changes in aerodynamic performance. While the effect is modest in the short term, it could become significant over long exposure times. The results are obtained under simplifying assumptions, such as a smooth surface and no detachment of particles. Further refinement is achieved by simulating particle deposition on an airfoil exposed solely to wind, where the wind velocity is modeled using a simple stochastic approach. The simulations account for both particle accumulation and instantaneous detachment during the run, and additional detachment is evaluated in a post-processing step. The resulting surface modification is then used to study its effect on the aerodynamic performance, providing a more complete understanding of how dust environments influence drone operation in planetary exploration. Overall, the findings contribute to a deeper understanding of low Reynolds number aerodynamics and environmental degradation mechanisms relevant to Martian rotorcraft. The results offer guidance for aerodynamic model selection, design optimization, and long-term operational strategies for future aerial exploration missions on Mars

Water-lubricated high-performance polymers

Polymer-composites are indispensable tribo-materials in a wide range of engineering applications, including gears, bearings, joint implants, and automotive components. In many of these applications the presence of liquid lubricant is unavoidable, requiring a thorough understanding of composite behaviour under lubricated conditions. However, with growing emphasis on environmental safety, the use of petroleum oil-based lubricants, especially near aqueous environments, such as ships, pumps and turbines, has become increasingly dubious. Estimates suggest that of the 30–40 million tonnes of lubricant used annually, around 55% may eventually re-enter the environment, with approximately 95% of these being petroleum-based. These systems contribute to emissions and resource depletion, driving interest in the development of lubricant technologies free from petroleum-derived products. Some potential replacements to them are acceptable alternate lubricants like esters and glycerol, or mere water, which is abundantly available and emission free. The tribological performance of polymer composites often differs between dry and lubricated conditions, as contribution from polymer and fillers are observed to vary across environments. While numerous studies have explored the role of various fillers in water lubricated conditions, limited knowledge is available on other alternate lubricants. More recently, the focus on polymer-composite side has shifted towards multi-filler systems, which, when working synergistically, can provide superior performance compared to having a single filler. However, the existing literature lacks clarity on several key aspects: including the individual roles of filler material and scale; the nature and effect of filler–filler and filler–lubricant interactions to overall performance. This thesis investigates these gaps and provides deeper insights into the mechanisms governing the lubricated tribological behaviour of multi-filler polymer composites

Biokolproduktion i fluidiserad bädd reaktörer

This study explores the production of biocarbon from forest biomass through pyrolysis in fluidized bed reactors, emphasizing the relationship between the operating conditions, ash behavior, and physicochemical properties of the resulting solid biocarbon. Fluidized bed reactors offer distinct advantages for biocarbon production, including efficient heat transfer, isothermal operation, and scalability. These characteristics make them particularly suitable for integration into existing energy infrastructures. A key strategy investigated in this study is the use of a weakly oxidizing atmosphere composed of recycled flue gases from combustion processes as the fluidization medium. This approach enables heat integration with fluidized bed boilers and reduces the need for external inert gases, thereby lowering operational costs and improving the overall energy efficiency and circularity of the system. The impact of this atmosphere on biocarbon yield and composition was studied in detail, particularly regarding its influence on the behavior of ash-forming elements and textural properties. Special attention is given to the transformation and retention of ash-forming elements, such as potassium and phosphorus, which affect the suitability of biocarbon for industrial applications. The experimental and modeling results show that fluidized bed conditions favor the selective removal and distribution of these elements. Analytical techniques, including inductively coupled plasma (ICP), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and thermodynamic equilibrium calculations (TECs), were used to assess the mechanisms of ash transformation. In parallel, the evolution of particle properties, such as size, density, porosity, and surface area, was evaluated under different conversion regimes. Structural degradation owing to attrition and fragmentation was found to play significant roles in carbon retention and fines generation. Preliminary pilot-scale tests conducted with a different woody feedstock showed trends similar to those observed at the laboratory scale when comparable devolatilization severities were applied, reinforcing the transferability of key process–property relationships. Overall, these findings support the development of integrated and sustainable fluidized bed systems for biocarbon production, offering practical pathways to reduce fossil carbon use and improve resource efficiency in biomass valorization processes

Behandling av partiklar och metaller från dagvatten : Laboratoriemetoder och utvärdering i fält

Suspended solids and metals are recognized as key pollutants in stormwater runoff. Thus, stormwater treatment systems have become increasingly vital components of urban infrastructure, playing a key role in reducing pollutant loads entering receiving water bodies. This thesis focuses on evaluating the treatment of solids and metals in stormwater systems, through both controlled laboratory experiments and field-based assessments. Synthetic stormwater is widely used as a substitute for real runoff in both laboratory and field experiments. Its main advantages are the ability to control influent quality and quantity, as well as to improve the repeatability of experiments. However, no standardized formulation currently exists. A critical review which was conducted to evaluate the use of synthetic stormwater in experimental stormwater research revealed substantial variation among studies. Based on these findings, a narrower set of pollutant concentration ranges was suggested to enhance the comparability, repeatability, and reproducibility of future experiments. The experiments evaluating design parameters of a suggested Bottom Grid Structure demonstrated that hydraulic modifications of settling areas in the stormwater treatment systems could enhance sedimentation, though the results were not directly scalable to field conditions. Among the variable factors in the experiment, inclined cell walls of the Bottom Grid Structure had the strongest effect, increasing sedimentation by up to 22% compared to control runs. Column studies showed peat and bark to be the most effective filter materials for dissolved Zn removal, although the use of peat is associated with significant drawbacks regarding other pollutants and uncertainties about its long-term performance. Evaluated zeolite filter system treating copper roof runoff achieved high removal of Cu (49–85%) and Zn (48–94%) but exhibited declining performance over time. A field study examining the performance of two EcoVault facilities revealed relatively low TSS removal (40–46%), substantially below both previous EcoVault studies and manufacturer claims. Dissolved metals were inadequately removed, likely due to elevated hydraulic loading rates and progressive filter clogging. Sedimentation was identified as the dominant treatment mechanism, while the zeolite filter cassettes provided negligible additional metal removal. The field experiments underscored the importance of site-specific design of stormwater treatment systems, especially in cases where the influent is dominated by dissolved metals. Despite their limited performance, underground treatment systems remain a practical solution in densely built urban environments where surface space is constrained. However, targeted design improvements are essential to enhance treatment efficiency. Furthermore, comparisons with commonly used models for the prediction of the performance of stormwater treatment systems revealed that actual removal rates were approximately 50% lower than estimated values, highlighting the need for additional field-based data to improve model calibration and support the development of more reliable and context-sensitive stormwater treatment strategies

Water-Based Lubricants for Electric Vehicle Transmission Applications: Properties, Tribological Performance and Efficiency.

Water-based lubricants (WBLs) are emerging as promising alternatives to conventional oil-based lubricants in electric vehicle (EV) transmission systems, driven by increasing demands for energy efficiency, sustainability, thermal management, and environmental compatibility. OEMs and researchers are striving to minimise frictional, thermal, and power losses in EV gearboxes to maximise driving range and system durability, and WBLs have the potential to meet this demand. Moreover, WBLs offer flexibility in viscosity tuning, higher specific heat capacity, and superior heat transfer capability compared with oil-based lubricants. These characteristics create opportunities to improve cooling performance and support the development of a single e-fluid concept. However, their successful implementation requires a comprehensive understanding of film formation, friction and wear behaviour, system-level efficiency, and material compatibility. This thesis investigates the feasibility of WBLs for EV transmissions through a series of interconnected studies. It begins with the characterisation of elastohydrodynamic (EHL) film formation and pressure–viscosity relationships, revealing the distinctive film-forming behaviour of WBLs. The effects of water content and evaporation sensitivity on the pressure–viscosity coefficient are examined, and the applicability of classical predictive models, including the Hamrock–Dowson equation, is reassessed. Friction and wear analyses demonstrate that fully formulated WBLs can achieve near-superlubricity with minimal shear heating, facilitated by robust surface–additive interactions under rolling/sliding contact. These laboratory findings are validated through full-scale EV gearbox testing, where WBLs reduce power losses and thermal load, improving overall gearbox efficiency by at least 1.5%. Finally, durability is evaluated via tribocorrosion analysis of bearing steel, highlighting the synergistic interaction between mechanical and chemical wear in aqueous environments. Overall, this work positions WBLs as viable high-efficiency e-fluids for future sustainable transport, provided that challenges related to water loss and wear are effectively addressed through advanced formulation and system design

Performance of Lower-Carbon Concretes After High-Temperature Exposure

This research was initiated in response to the urgent need to reduce CO₂ emissions, the ongoing green transition within the building materials sector, and the persistent gap in both knowledge and practice regarding the performance of environmentally friendly concretes under high-temperature exposure. The study investigates the behaviour of concrete and paste mixtures incorporating ground granulated blast furnace slag (GGBFS) and calcium sulfoaluminate (CSA) cement following one hour of exposure to elevated temperatures. Mechanical testing, chemical analysis, including real-time monitoring during heating, and microstructural observations were used to evaluate thermal damage and to understand the materials’ response under those conditions. Various binder types, fillers, fibres, and admixtures were examined to assess their influence and to identify both strengths and limitations. The results demonstrated a beneficial effect of GGBFS in systems based on Portland cement, particularly in enhancing residual strength and thermal stability. In CSA-based systems, the inclusion of eggshell powder (ESP) was found to contribute positively to post-fire performance. On the other hand, certain admixtures caused unexpected disturbances at high temperatures, suggesting the need for careful compatibility and awareness of mix when designing thermally resistant concretes. The experimental programs were designed as an initial step toward broader exploration and formed a key component of an ongoing research effort. The findings are intended to support and complement existing studies in both academia and industry, with the goal of improving the fire resistance and overall durability of sustainable concrete materials