Luleå University of Technology Publications
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Examining the perceptions and permissions of reusing treated wastewater in a region facing water scarcity
No full textThis study aimed to evaluate the public’s perspective on the utilisation of reclaimed water in Al-Kut, Iraq. Accordingly, a survey consisting of multiple-choice questions was designed to gather demographic information and assess the participants’ views and knowledge about water resources and wastewater reuse. The replies of 507 Iraqis, consisting of 326 males and 181 females, were analysed using a T, one-way analysis of variance (ANOVA), and Chi-square tests. The study’s findings indicate that 90.6% of the people are conscious of the issue of water crisis problem, whereas the others 9.4% either deny its existence (6.6%) or are uncertain about it (2.8%). Based on the survey questions, a high percentage (about 41%) of respondents have no idea that there is a water crisis. Nevertheless, the majority (88%) of individuals are implementing strategies to preserve water and are open to incurring additional charges for the installation of centralised wastewater treatment plants in the area. Many individuals support the utilisation of reclaimed water for agricultural and industrial applications. The findings also indicated a statistically significant relationship between sex, income, and acceptance of wastewater reuse. Incentives for reusing treated wastewater and opposition against it were ranked by the respondents.Validerad;2025;Nivå 2;2025-11-20 (u2);Full text: CC BY license;</p
QoE-Aware XR Service Placement in the Edge—Cloud Continuum
No full textExtended Reality applications require low latency and high computation power, often exceeding the capability of end devices like Head Mounted Displays (HMD). To support such requirements, XR workloads are increasingly delegated to edge-cloud systems. This thesis tackles the challenge of XR service placement and provisioning in the edge-cloud continuum with the aim of optimizing Quality of Experience (QoE) while improving system energy and carbon emissions efficiency. The problem is formulated as a Markov Decisions Process and a Deep Q-Learning (DQL) agent is proposed to learn the XR service placement policies in a dynamic environment. A validated QoE model is incorporated into the reward function and the agent utilizes several methods like Double DQN, experience replay, and epsilon-greedy exploration to enhance the stability of the training procedure. Evaluation in a simulation environment reveals that the DQL agent learns the ability to navigate the environment effectively and attain greater reward across the steps of the training procedure. The agent outperforms a round-robin baseline, achieving higher system- wide QoE with superior system energy consumption and carbon emissions per unit of QoE and with moderate rates of service migrations. These findings demonstrate that reinforcement learning provides an effective framework for QoE-aware XR service placement in the edge-cloud continuum
Impact of Mg Doping on Structural, Morphological and Thermoelectric Properties of SnO2 Nanoparticles: A Combined Experimental-Theoretical Investigation
No full textRecent advances in nanotechnology, including the development of nanoparticles, thin films, and superlattices, have revitalized research in thermoelectricity by enabling independent control of thermal and electrical transport, overcoming longstanding efficiency limitations and expanding opportunities for sustainable energy generation and miniaturized device applications. Tin dioxide (SnO2) has recently attracted increasing attention as a thermoelectric material owing to its properties, such as high-temperature chemical and structural stability, non-toxicity, and the abundance of constituent elements. Current research efforts have been directed toward enhancing its thermoelectric performance through strategies such as elemental doping, nanostructuring, strain engineering, and the development of composite systems. In this study, we investigate the effects of Mg substitutional doping on the thermoelectric characteristics of SnO2. We synthesize undoped and Mg-doped SnO2 nanoparticles (0.05%, 0.10%, and 0.15%) using a straightforward hydrothermal technique. The investigation of the undoped and doped materials revealed that SnO2 possesses a tetragonal rutile-type structure, as determined through structural and morphological examination. The crystalline size of all of the samples decreases as the Mg doping concentration is increased. Hall measurement and Seebeck coefficient measurements have been employed for assessing the thermoelectric characteristics. As the Mg content increased, both the Seebeck coefficient and electrical conductivity value increased from −20 μV/K to −91 μV/K and 29.8 S/cm to 112.6 S/cm, confirming the presence of semiconductor behavior. The 0.15% Mg-doped sample demonstrates the highest power factor when evaluated at a temperature of 150 K, yielding a value of 9.4 × 10−5 WK−2m−1.Validerad;2025;Nivå 2;2025-11-21 (u8);Funder: European Union—NextGenerationEU (ECS00000033, PE0000021); FAR 2024 Progetti interdisciplinari—Linea (CUP E93C24001920005); MUR PRIN (2022L4YZS4)Full text license: CC BY</p
High‐Efficiency Semitransparent Solar Cells Based on Magnetron Sputtered Sb2S3 Thin Films
No full textThin-film solar cells based on wide-bandgap antimony sulfide (Sb2S3) offer new possibilities for semitransparent building-integrated photovoltaics. In this report, impurity-free Sb2S3 thin films are prepared by radio frequency magnetron sputtering. The optimized opaque devices obtain a high power conversion efficiency (PCE) of 4.6%. A detailed characterization is conducted to investigate the impact of annealing conditions on the morphology, crystal structure, composition, and optoelectronic properties of Sb2S3 thin films, which are relevant to photovoltaic performance. Moreover, semitransparent solar cells are fabricated using highly compact Sb2S3 films with thicknesses of 40, 60, and 80 nm. Using a superstrate device structure (FTO/TiO2/Sb2S3/P3HT-PEDOT:PSS/Au (≈10 nm)), these solar cells achieve PCEs of 2.0%, 2.6%, and 3.2%, respectively, while maintaining an average visible transmittance (AVT) of 15.5%, 13.5%, and 10.0%. The AVTs of the semitransparent devices are further enhanced by replacing the ultrathin Au top electrode with indium-doped tin oxide and using wide bandgap inorganic CuSCN as the hole transport layer instead of P3HT-PEDOT:PSS. Thus, the AVT improves to 20.5% (PCE: 2.0%) for semitransparent solar cells using 60 nm Sb2S3. This study demonstrates that sputtering is a promising deposition technique for high-quality ultrathin Sb2S3 absorbers for semitransparent photovoltaics. Funder: Ministero dell’Università edella Ricerca (MUR) (CUP D43C22003090001); European Union–NextGenerationEU Award Number (PE0000021); NextGenerationEU (IR0000027, CUP: B33C22000710006)Full text license: CC BY</p
Optimizing maintenance strategies for aircraft repairable units with hidden functions under periodic inspection and imperfect restoration
No full textThe study presents a decision support model for optimizing aircraft maintenance plans, targeting repairable units with hidden functions. The model addresses the complexities of integrating multiple factors, such as aging, the availability of hidden functions during operation, the varying effectiveness of restoration and repair tasks, and the operational and economic consequences of failure.It considers a combination of inspections, restorations, and a discard task at the unit’s predefined renewal age, for the “non-safety effect” failure category. It incorporates the Kijima type II model to account for the effect of imperfect restoration and the concept of mean fractional dead time to identify the optimal intervals for inspections, the number of inspections needed within each restoration cycle, and the frequency of restorations in a renewal cycle. Real-world adapted numerical examples are used to demonstrate the model’s application. Sensitivity analysis further enhances the model’s utility by determining the influence of reliability and cost parameters on maintenance optimization outcomes. The results show that, in the absence of aging, restoration effectiveness has a profound effect on the total cost and optimal set of solutions. With as-bad-as-old restoration effectiveness, the optimal alternative involves maximizing the number of inspections without resorting to restoration. Conversely, with as-good-as-new restoration effectiveness, the optimal alternative should harmonize a moderate number of inspections with a moderate number of restorations. Additionally, the influence of the costs associated with restoration and accidents suggests that frequent inspections at smaller intervals are essential to mitigate the risk of failure. Maintenance managers can utilize the proposed model as a practical tool to optimize maintenance by comparing and selecting strategies based on effectiveness and cost parameters, thereby enhancing the reliability of repairable systems with hidden failures.Full text license: CC BY</p
Accounting for migration: An inquiry into a research conversation in the margins
No full textThis article provides an assessment of previous research on the nexus between accounting and migration. Despite ideas of accounting and migration interlinking in many ways, and with migration as one of the most important global challenges, the research conversation is limited and sprawling. Four different streams are discerned in the nexus between accounting and migration: i) historizing the migrant, ii) controlling migrants at the border, iii) constructing the employable migrant, and iv) listening to the voices of migrants. Based on a cross-stream analysis, five interrelated roles of accounting in the making of migrants and migration are highlighted, roles that also serve as springboards to suggestions for future research. Validerad;2025;Nivå 2;2025-09-09 (u8);Funder: Handelsbanken Research Council;Full text license: CC BY</p
A tribological perspective on friction and performance in Olympic snow and ice sports
No full textWith 62% of medals at the upcoming 2026 Winter Olympics in Milano-Cortina to be awarded in skiing disciplines and the remaining 38% in ice-based events, understanding the determinants of performance is critical. Despite extensive examination of athletes’ physiological, biomechanical, and psychological attributes, the role of tribology—particularly in understanding friction on snow and ice—has received less attention. This is a scientific perspective article outlining key tribological factors and highlighting their importance in Olympic winter sports. In skiing, optimising the ski–snow interaction requires a comprehensive understanding of how friction is influenced by snow crystal morphology, temperature, ski base material and structure, ski stiffness, skier technique, and environmental conditions. For ice-based events, friction is determined by a combination of ice surface roughness, temperature, and sport-specific preparation techniques, as well as equipment design (e.g. blade material and geometry, the running surface finish of curling stones) and athlete technique (e.g. angle of attack in speed skating, sweeping in curling). Ice preparation techniques further influence friction, with specific conditions tailored to each sport. In conclusion, advancements in Olympic winter sports have been significant. However, future breakthroughs in performance may lie in applying tribological insights to optimise the complex interactions between athletes, equipment, and the unique properties of snow and ice. This perspective article aims to guide future research by synthesising current understanding and identifying emerging challenges in winter sports tribology.Validerad;2025;Nivå 1;2025-11-28 (u5);Full text license: CC BY;Funder: Swedish Olympic Committee (SOK)</p
Cognitive bias in perceived concern with rainfall: Implications for climate adaptation
No full textRainfall data usually comprise large sets of complex information, with data points spread across both time and space. To be understood, such environmentally significant data must be integrated—but distribution shapes can bias this integration process. Distribution biases can lead to differing levels of concern with rainfall, and in turn, alter the perceived importance of climate adaptation measures. In three experiments, participants reported greater concern about rainfall and reported stronger climate adaptation intentions when rainfall distributions were negatively skewed compared to positively skewed, even though both distributions contained identical total rainfall. This cognitive bias from skewed distributions persisted in both retrospective judgments of entire stimulus sets, and in evaluations of additional instances of rainfall, and it depended on foreknowledge of stimulus context (i.e., the shape and endpoints of the distribution). The results demonstrate how cognitive bias can influence the formation of environmental attitudes.Validerad;2025;Nivå 2;2025-10-22 (u4);Full text license: CC BY</p
Effect of the spike anchors on the failure mode of a FRCM system applied to a curved masonry substrate
No full textStrengthening existing masonry arch structures with externally bonded composite systems has become a common technique to enhance structural performance while allowing continued use of the infrastructure during retrofitting. Among these systems, textile-reinforced mortar (TRM) solutions applied to the intrados of arches have shown promising results. The effectiveness of mortar-based materials, such as fabric reinforced cementitious matrix (FRCM), TRM, and steel reinforced grout (SRG), relies heavily on the interaction between the matrix, the masonry substrate, and the embedded fibres. However, when applied to concave masonry surfaces, the curvature introduces additional normal stresses that may hinder stress transmission and bond performance. This study investigates how substrate curvature and the use of spike anchors influence the failure mechanisms in FRCM strengthened masonry. Single shear-lap tests were conducted on curved masonry specimens to analyse load transfer behavior and identify failure modes. The results reveal that curvature significantly alters typical failure mechanisms observed on flat substrates, even leading to the emergence of subcategories within standard failure modes. Moreover, the incorporation of spike anchors was found to locally modify failure progression, improving overall bond performance. The paper presents a detailed classification of observed failure modes, supported by histograms that quantify the effect of curvature and the spike anchors. These findings provide valuable insight into the design of strengthening systems for curved masonry elements and highlight the importance of tailored anchorage strategies.Validerad;2025;Nivå 2;2025-08-06 (u4);For funding ingormation see here: https://www.sciencedirect.com/science/article/pii/S2352012425013372?via%3Dihub;Fulltext license: CC BY</p
Experimental investigation of solar radiation effects on Mercury’s surface regolith
No full textThe surface of Mercury is exposed to extreme diurnal thermal variations caused by the high intensity of solar radiation, the radiative loss due to the planet’s lack of atmosphere, its eccentricity and its 3:2 spin - orbit resonance. This work presents an experimental study on terrestrial rocks used as Mercury analogues subjected to hermean conditions. We simulate the power density of a planetary surface at Mercury’s perihelion distance of 0.31 au using the Space and High-Irradiance Near-Sun Simulator (SHINeS) at Luleå University of Technology. The reflectance spectra were acquired in the visible and near-infrared wavelength range for every sample before and after irradiation. Permanent spectral changes are observed in all samples towards the longer wavelengths in the visible spectrum after only one thermal cycle. Darkening is evident in both the visible and near-infrared spectrum ranges, combined with reddening in the visible-to-near-infrared region in most of our samples. We propose that darker samples like boninite, basalt, and diorite are more likely to experience spectral changes due to their low albedo. Validerad;2025;Nivå 2;2025-08-06 (u8);Full text license: CC BY</p