Luleå University of Technology Publications
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Cultivating the Next Generation: How Teacher Leadership Identity Shapes Aspirational Engagement with Students in Compulsory School
No full textA global decline in students’ motivation and academic performance poses a serious threat to future competence supply, particularly in knowledge-driven economies such as Sweden. Despite higher education’s growing importance for economic and social mobility, the number of students pursuing such education continues to fall. This study employs a mixed-methods design using an explanatory sequential approach to explore how teachers’ leadership identity influences their aspirational engagement in shaping students’ beliefs and intentions to pursue higher education and future career opportunities. The results show that teachers who identify strongly with their leadership role exhibit a type of leadership that influences aspirational engagement with students. This, in turn, may promote students’ beliefs in their potential and intentions to pursue higher education through (1) aspirational engagement in individual dialogues with students, (2) aspirational engagement when introducing new subject areas in whole-class communication, and (3) aspirational engagement related to practical work experience (PRAO). This study demonstrates an understanding of the important potential of teachers’ contributions to elevate society’s future competence supply.Fulltext license: CC BY</p
Experimental and theoretical study on ion association in [Hmim][halide] + methanol/dimethyl sulfoxide mixtures
No full textThe electrical conductivities of 1-hexyl-3-methylimidazolium halides ([Hmim][halide], halide = Cl–, Br–, I–) were measured in methanol (MeOH) and dimethyl sulfoxide (DMSO) at dilute concentrations from 293.15 to 313.15 K, alongside liquid density measurements for parametrization. Molar conductivity (Λ) decreased with increasing IL concentration and decreasing temperature, with solvent effects predominating over those of anion size. Λ was higher in MeOH than in DMSO due to lower viscosity and greater ion dissociation of MeOH. Comparison with a previous study involving H2O, MeOH, DMSO, and isopropanol confirmed that solvent viscosity is the dominant factor influencing Λ at infinite dilution. At higher IL concentrations, Λ in MeOH fell below that in H2O, likely due to a reduced number of free ions and the formation of larger solvated ion complexes.To analyze conductivity behavior, the Debye-Huckel-Onsager model was employed to determine the limiting molar conductivity (Λ0), which was subsequently used in the Shedlovsky equation to calculate the association constant (KA). For comparison, simultaneous regression of Λ0 and KA was also performed. The results indicated that, within the same solvent, Λ0 increased with temperature, while KA exhibited irregular trends. Across different solvents, Λ0 correlated with solvent viscosity, and KA was influenced by dielectric constant and polarity. Solvent effects on both Λ0 and KA were more pronounced than those of anion size, suggesting the dominant role of the solvent environment. Positive Eyring activation enthalpies showed the endothermic ion-pairing process. Additionally, the Walden product suggested stronger ion-solvent interactions and larger solvated ions in MeOH compared to DMSO. These findings provide deeper insight into IL conductivity in diverse solvent environments.Validerad;2025;Nivå 2;2025-10-17 (u8);Full text license: CC BY;Funder: State Key Laboratory of Material-Oriented Chemical Engineering; </p
Designwise: Design principles for multimodal interfaces with augmented reality in internet of things-enabled smart regions
No full textTechnological developments, such as mobile augmented reality (MAR) and Internet of Things (IoT) devices, have expanded available data and interaction modalities for mobile applications. This development enables intuitive data presentation and provides real-time insights into the user’s context. Due to the proliferation of available IoT data sources, user interfaces (UIs) have become complex and diversified, while mobile devices have limited screen spaces. This state increases the necessity of design principles that help to secure sufficient user experience (UX). We found that studies of design principles for IoT-enabled MAR applications are limited. Therefore, we conducted a systematic literature review to identify existing design principles applicable to IoT-enabled MAR applications. From the state-of-the-art research, we compiled and categorized 26 existing design principles into seven categories. We analyzed the UIs of three IoT-enabled MAR applications with the identified design principles and user feedback gathered from each application’s evaluation to understand what design principles can be considered in designing these applications. Among the 26 principles, we find eight principles that are commonly identified as possible improvements for the applications based on their purposes. We demonstrate the practical use of the identified principles by redesigning the UIs, and we propose five new design principles derived from the application analysis. As a result, we summarized a total of 31 design principles, including the five new ones. We expect that our findings will give insight into the UX/UI design of IoT-enabled MAR applications for researchers, educators, and practitioners interested in UX/UI development.Validerad;2025;Nivå 2;2025-11-25 (u4);Funder: Korea Ministry of Science; ICT;Fulltext license: CC BY</p
The relation between linguistic accuracy and scoring of Swedish EFL students’ writing during a high-stakes exam
No full textThis paper examines the effect of linguistic accuracy (e.g., the lack of form, grammatical, and lexical errors) on scoring during the high-stakes national test of English in Swedish upper secondary school. Teachers are expected to score their own students’ texts with the help of assessment instructions containing benchmark texts (i.e., texts representing different score bands). The assessment instructions and the score bands provided to guide scoring are not explicit about how accuracy should influence scores. Two research questions were answered: As measured by ordinal regression, to what extent does linguistic accuracy predict rater scores? Do the texts scored by teachers reflect the graded example texts in terms of how linguistic accuracy predicts scores? The results revealed, amongst other things, that overall frequency of errors in texts significantly predicted scores as the model explained approximately 58 % of the variance in the outcome variable according to Nagelkerke’s pseudo R-squared. Accuracy also had a similar effect on scores in texts rated by teachers as in the benchmark texts. In relation to the findings, it was concluded that accuracy may have more of an impact on scores than constructs that are more explicit components of the score bands such as lexical complexity.Full text license: CC BY 4.0;</p
Enabling environmental education – value hierarchies of sustainability objectives for upper-secondary school
No full textAchieving an environmentally sustainable society and meeting international obligations such as the U.N. Paris Agreement, the 2030 Agenda for Sustainable Development, and the EU Green Deal requires all policy sectors to integrate environmental sustainability. Education, as a sector shaping our citizens of tomorrow, has a critical role in this transition. This study explored how sustainability objectives are prioritized within educational policies, using Sweden as a case study to assess the preconditions for effective environmental education in upper-secondary classrooms. Applying Environmental Policy Integration as a theoretical framework, the research employs content analysis and crisp set analysis to examine policies governing classroom practices and identify the value hierarchies embedded regarding sustainability. The analysis focuses on the national curriculum (2011) and the syllabi for the eight common subjects in two versions: the 2011 and 2025 revisions. Findings revealed that Swedish upper secondary policy predominantly favors the social dimension of sustainability. Environmental priorities present in the national curriculum do not consistently trickle down to subject syllabi, and only the subject of science displayed a principled priority of the environment; although this was only evident in earlier versions of the syllabi. This study concludes that for education to meaningfully contribute to a sustainability transition, policies need a stronger environmental emphasis, particularly policies that inform teachers’ everyday work and the exercise of public authority, such as subject grading criteria.Full text license: CC BY-NC;Related dataset: 10.5878/tddg-wm38</p
Quantitative raman thermometry and N2+ detection in a non-transferred plasma torch
No full textQuantitative laser-based diagnostics like Raman spectroscopy are essential for studying high-temperature processes, but their application in intensely luminous and transient environments such as plasma torches is severely limited by overwhelming background emission. This study focuses on the quantitative thermometry of a 7 kW atmospheric air plasma jet, an environment where such measurements are notoriously difficult. To enable these measurements, a Polarization Lock-In Filtering (PLF) Raman technique is used to suppress the intense and fluctuating plasma background. The method successfully yields high-quality N2 ro-vibrational spectra along the jet’s central axis. Model-based fitting of these spectra produces a detailed axial temperature profile, showing a decay from over 3700 K near the nozzle. Furthermore, the high signal quality enabled the detection of singly ionized nitrogen (N2+) in the plasma core, providing direct evidence of its ionized state. These results represent the first application of PLF for thermometry in a plasma torch and provide critical experimental data for validating magnetohydrodynamic simulations. Full text license: CC BY</p
Wearable luminescent solar concentrators based on carbon dots crosslinked hydrogels
No full textWearable luminescent solar concentrators (LSCs) hold significant promise for integrating energy harvesting with flexible textiles. However, most currently reported LSCs are either rigid or liquid-filled, making it challenging to achieve flexible devices with high efficiency and mechanical robustness. Here, we introduced Ca²⁺-capped carbon dots (C-dots) as dual-functional agents, simultaneously crosslinking sodium alginate hydrogels and serving as luminophores, eliminating the need for additional dopants. The resulting hydrogels exhibited tunable mechanical strength (0.25 MPa at 50 % strain), high transparency (64 % visible transmittance), and good stability. As a proof-of-concept, we fabricated wearable LSCs by embedding the hydrogel into flattened polyvinyl chloride tubes and weaving them into textiles. Under natural sunlight illumination (50 mW/cm²), the as-fabricated flexible LSC achieved a power conversion efficiency (ηPCE) of 0.26 % and an optical efficiency (ηopt) of 2.60 % with 64 % average visible transmittance. Remarkably, the device retains 72 % of its initial optical efficiency after 24 h continuous ultraviolet illumination (468 mW/cm2). This work demonstrates the first hydrogel-based LSCs for practical wearable energy harvesting.Full text: CC BY license;For funding information, see: https://doi.org/10.1016/j.nanoen.2025.111674</p
Efficient Pipeline Design for Real-Time RNN-based Anomaly Detection in Embedded Edge AI Systems
No full textThis master's thesis explores and evaluates how to design efficient edge AI pipelines for anomaly detection. The deep learning architecture used was a recurrent neural network (RNN) autoencoder, capable of reconstructing and detecting abnormal data points, suitable for resource-constrained embedded systems. It investigates how such models can be executed on the ESP32-P4 MCU using Zig as the primary programming language. The main goals are to evaluate model accuracy, latency (throughput), and memory footprint for real-time use cases. The proposed solution uses a compact Recurrent Neural Network autoencoder trained on time-series data from the SMAP and MSL datasets to detect anomalies in univariate signals. The system performs inference without any dynamic memory allocation, using compile-time Matrix and Layer types built from scratch, and compiles them into the same trained model used in PyTorch. Benchmarking on the ESP32-P4 showed a latency way below 2 ms per window, with a peak throughput (latency) of approximately 786 predictions per second for the final optimized build. The model generalization achieved an F1-score of 0.6075 and an AUROC of 0.667 on the E-3 channel (dataset), while maintaining a total memory footprint of ≈3.875 KB and an average energy consumption of 0.772 mJ per inference. The result demonstrates that deep learning models can run deterministically on low-powered hardware using Zig's safety-aware programming model. Moreover, this thesis contributes to a reproducible toolchain, a Zig runtime for RNN inference, and a benchmark methodology that links accuracy, latency, and memory usage in edge AI embedded anomaly detection.
Artificial neural networks combined with quotients to preprocess Raman Spectra from different setups
No full textRaman spectroscopy is widely used in chemistry, material science and in biomedical applications such as cancer detection. A Raman spectrum of tissue shows DNA, amino acids, lipids, and proteins simultaneously, which makes the evaluation of the spectral content both complete but also challenging. The impact of the technique can increase substantially by access to big databases, but variations in the setup, e.g. quantum efficiency of Raman detectors, transmission profiles and disturbances of optical filters and components, may hinder direct data comparison. We here introduce a step prior to preprocessing that calculates spectral quotients to address system-dependent multiplicative differences and system-inherent background noise, thereby enabling analysis of Raman spectral data from different setups. Pre-processing was performed using an artificial neural network (ANN) trained on synthetic data to deal with fluorescent background and noise. Validation by multivariate analysis of the spectral quotients combined with ANN was performed on randomized synthetic data and, as a proof of principle, on experimental data from brain tumor biopsies. The results demonstrated clustering and feature extraction that was not possible without the introduction of the quotients. Data exploration revealed that the method enabled spectral feature identification even for weak Raman signals that are not in resonance with the excitation wavelength. Note, some distortions persist due to data dependency and additive errors but a system independent clustering was achieved. ANN-based preprocessing combined with spectral quotients for combined evaluation of Raman spectroscopic data from multiple setups opens the possibility for more robust multivariate studies in biomedical and other applications.Full text license: CC BY 4.0;</p
Cirkulär ekonomi som drivkraft för varumärkeskapital i skogsindustrin : En fallstudie inom träförädlings- och byggmaterialsbranschen
No full textDenna studie syftar till att undersöka hur cirkulära strategier kan användas som en resurs för att stärka företags varumärkeskapital inom skogsindustrin, med särskilt fokus på träförädlings- och byggmaterialsbranschen. Studien har ett explorativt forskningssyfte och genomförs med en kvalitativ metodansats. Datainsamlingen utfördes genom elva semistrukturerade intervjuer. Analysen genomfördes med tematisk analys och utgick från etablerade teorier om varumärkeskapital samt ramverk för cirkulär ekonomi. Resultaten visar att cirkulära strategier som fokuserar på resurseffektivitet och förlängd produktlivslängd uppfattades som mest värdeskapande för skogsindustriföretagen. Dessa strategier visade sig ha en stor potential att stärka företagens ekonomiska resultat, samt bidra till en förändrad samhällssyn på träbaserade produkter. Det visade sig även att cirkulära strategier som fokuserar på återbruk och återanvändning inte hade någon positiv påverkan på företagens varumärkeskapital då certifieringskrav och klassificeringssystem skapar hinder för strategin i dagsläget. Sammanfattningsvis bidrar studien med ökad förståelse för sambandet mellan cirkulär ekonomi och varumärkeskapital i skogsindustrin. Det visade sig att cirkulära strategier inte driver varumärkeskapital trots att det finns en stark diskurs om hållbarhet. I stället visade det sig att cirkulära strategier fungerar som en sorts hygienfaktor/legitimitetskrav för företagen, snarare än en differentierande faktor för varumärkeskapital i denna kontext. Resultaten har både teoretiska och praktisk relevans genom att belysa hur företag inom skogsindustrin bör integrera och behandla cirkulära strategier för att stärka sitt varumärkeskapital. This study aims to investigate how circular strategies can be used as a resource to strengthen companies’ brand equity in the forest industry, with a particular focus on the wood processing and building materials industries. The study has an exploratory research purpose and is conducted using a qualitative methodological approach. Data collection was carried out through eleven semi-structured interviews. The analysis was conducted using thematic analysis and was based on established theories of brand equity and circular economy frameworks. The results show that circular strategies focusing on resource efficiency and extended product life were perceived as most valuable for forest industry companies. These strategies were found to have great potential to strengthen companies’ financial results and contribute to a change in society’s view of wood-based products. It was also found that circular strategies focusing on reuse and recycling had no positive impact on companies’ brand equity, as certification requirements and classification systems currently create obstacles to the strategy. In summary, the study contributes to a greater understanding of the relationship between the circular economy and brand equity in the forest industry. It was found that circular strategies do not drive brand equity, despite the strong discourse on sustainability. Instead, it was found that circular strategies function as a kind of hygiene factor/legitimacy requirement for companies, rather than a differentiating factor for brand equity in this context. The results have both theoretical and practical relevance by highlighting how companies in the forest industry should integrate and treat circular strategies to strengthen their brand equity.