Luleå University of Technology Publications
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ISSUES: Information security and digital services for sustainable designs : Report 2023-2025
No full textCognitive Neuroscience in Alpine Skiing: Introducing Computational Sports Medicine for Performance Optimization
No full textWhile sport psychology has long emphasized mental and cognitive aspects of performance, sports medicine has traditionally focused on musculoskeletal and physiological aspects, largely overlooking the brain's central role in athletic performance. This narrative review aims to bridge this gap by introducing Computational Sports Medicine, a novel framework that integrates cognitive neuroscience with established physiological and biomechanical measures. Using alpine skiing as a primary example, this review examines the critical role of working memory updating in dynamic environments, discusses how neural processes enable adaptation, and proposes Computational Sports Medicine as a unifying predictive framework. This approach moves beyond descriptive analysis to provide objective, quantifiable metrics, testable models, and the ability to simulate “what-if” scenarios for proactive intervention. Practical implications for training include developing sport-specific cognitive tasks, individualizing variability in motor and cognitive learning, and leveraging technologies like virtual reality and wearable sensors. The review primarily targets elite and sub-elite athletes, for whom cognitive and environmental demands are most pronounced. This brain-inclusive framework offers a personalized approach to performance optimization, injury prevention, and safe return-to-play decisions, positioning the brain as the central organ to the future of sports medicine.Full text license: CC BY</p
Optical Frequency Comb Generation and Injection Locking for Photonic Receiver Applications
No full textHeterodyne down-conversion of radio frequencies from an optical carrier can be achieved by mixing the carrier with a frequency offset copy of itself. A stable yet tunable frequency offset allows for wideband down-conversion and is of interest for photonic receiver applications. This thesis investigates a method for creating a stable carrier copy by means of optical injection locking with a secondary semiconductor laser. A setup is used where the carrier field is generated by a laser and is broaden into an optical frequency comb by electro-optic modulation before being injected into the second laser. Depending on the frequency offset and power difference between the lasers, one comb line can be amplified, creating a copy of the carrier at a fixed frequency offset. Optical injection locking is found to successfully amplify only one comb line while suppressing the remaining comb below the noise floor of the detector, resulting in a sideband suppression ratio over 43 dB. The frequency offset stability between the lasers is found to be limiting for the suppression since the low injection ratio needed for near or below the noise floor suppression is accompanied by a narrow locking width
Experimental study on the permeability characteristics of reconsolidated salt: Effects of gas and confining pressure
No full textReconsolidated salt, formed from crushed halite under compaction, is a promising buffer and sealing material for deep geological repositories of high-level radioactive waste (HLW) because of its low permeability and self-healing properties. This study investigated the gas permeability behavior of reconsolidated salt with varying porosities under different confining pressures and inlet gas pressures using nitrogen gas. Based on nuclear magnetic resonance (NMR) technology, the pore structure of reconsolidated salt specimens with different porosities was tested and imaged. The experimental results demonstrate that gas permeability decreases with increasing gas and confining pressures, with gas pressure having a more pronounced effect. The observed permeability‒pressure relationship is attributed primarily to the Klinkenberg effect, with gas slippage along pore walls enhancing the measured permeability under low-pressure conditions. Using the Klinkenberg correction, the absolute permeability values of reconsolidated salt were derived, reaching as low as 10−19 m2 in low-porosity samples. These values are significantly lower than the apparent gas permeability, indicating excellent sealing performance comparable to or superior to that of bentonite. A logarithmic relationship between the absolute permeability and confining pressure was established, providing a quantitative basis for permeability prediction under repository stress conditions. NMR imaging results indicate that with decreasing porosity, the connectivity between pores also gradually diminishes. Additionally, the slip factor was found to increase with increasing confining pressure, underscoring the evolving influence of pore geometry on gas transport mechanisms. Permeability of reconsolidated granular salt decreases with porosity following a power-law relationship, and the healing supports its sealing effectiveness. This study provides essential data and theoretical insights for evaluating the long-term sealing performance of reconsolidated salt in salt-based HLW repositories.Full text license: CC BY 4.0;Funder: Rut and Sten Brand foundation; Chongqing Youth Innovative Talent Project (CSTB2024NSCQ-QCXMX0011); National Natural Science Fund of China (No. 52274073); National Key R&D Program of China (2024YFB4007100); China Postdoctoral Science Foundation (2023M730427); Chongqing Postdoctoral Research Project (2023CQBSHTB3139); Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety (SKLGGES-024006) </p
Experiences of cancer care among people living in rural areas : A qualitative literature study
No full textCancer är vanligt och personer bosatta i glesbygd har ofta begränsad tillgång till specialiserad sjukvård i närområdet. Av denna anledning behöver många personer bosatta i glesbygd resa långa avstånd för att få tillgång till cancervård som vanligtvis är lokaliserad till större sjukhus. Syftet med denna litteraturstudie var att beskriva hur personer bosatta i glesbygd upplever cancervård. Studien genomfördes som en litteraturstudie med ett inifrånperspektiv, där tretton kvalitativa artiklar analyserades genom kvalitativ innehållsanalys. Resultatet visade att personer i glesbygd upplevde oro över vårdens kvalitet och tillgänglighet samt att långa resor i samband med behandling var tidskrävande och påfrestande för vardagen. Vidare framkom att kostnader kopplade till behandling och resor skapade stress. En känsla av ensamhet och isolering kunde uppstå och betydelsen av vård nära hemmet och familjen var framträdande. Det framkom även att det fanns behov av socialt och praktiskt stöd för personerna. Slutsatserna är att personer som bor i glesbygd möter särskilda utmaningar som sträcker sig bortom själva cancerdiagnosen. För att kunna tillgodose dessa personers behov krävs en ökad förståelse för den komplexa livssituationen som uppstår när behandling innebär att under perioder vistas långt från hem och närstående.
Log detection for autonomous forwarding using auto-annotated data from a real-time virtual environment
No full textObject detectors for autonomous forestry operations have previously been developed mainly by training on physical manually annotated data, which is both time-consuming and costly. Since the ground truth in the virtual model is known, the training data can be auto-annotated, enabling the creation of larger training datasets, while also improving time and cost efficiency. In this work, a virtual environment in Unity is used in co-simulation with a real-time digital twin of a physical forestry vehicle, to generate realistic auto-annotated training data, as captured by an onboard stereo camera. First, it is shown that a log detector trained on physical data can detect logs in the virtual environment. Second, new detectors are trained, using different shares of virtual and physical data. It is shown that a detector trained using only virtual data, can learn to detect logs in the physical world. Moreover, virtual pre-training is shown to improve the performance of physically trained and tested detectors, both at low availability of physical training data, and in terms of domain generalization. A detailed detector performance analysis also highlights further potential and opportunities for future improvements. Furthermore, the real-time capable virtual models enable future machine learning tasks utilizing different levels of Hardware-in-the-Loop. Validerad;2025;Nivå 2;2025-09-23 (u8);Funder: Skogstekniska Klustret (The Cluster of Forest Technology);Full text license: CC BYSustainable Autonomous Material Handling (SAMHand)AutoPlant
Status overview of the torrefaction technology, its limitations, and prospective solutions: A reactor design and performance viewpoint
No full textThe goal of torrefaction is to transform lignocellulosic biomass into a solid product with better characteristics than raw biomass. Torrefaction is especially helpful when converting biomass into a final energy carrier via thermochemical processes like gasification and direct combustion. However, even though torrefied biomass has demonstrated advantageous quality, the prevailing torrefaction methods are not yet considered sufficiently advanced to overcome certain operational difficulties such as finding the proper balance between salient independent variables like temperature, reaction time and particle size; hence, much of the torrefied products obtained exhibit inconsistent properties. The technique also lacks the ability to efficiently handle a wide range of biomass feedstocks and exhibits scale-up issues that could be linked to poor temperature control and non-uniform heat distribution. Many of the existing torrefaction systems have been developed and validated for use in the processing of wood-based materials. Studies performed with non-woody materials yielded unsatisfactory results due to their inclination to ignite and carbonize readily during torrefaction. This review, therefore, presents a status overview of torrefaction technology and discusses the limitations of the technique from a reactor design perspective, as well as identifies system-level research that could potentially help to address the technology’s constraints. The basic principles of torrefaction and the mechanisms that affect the quality of torrefied products, including key process variables and kinetics are also discussed. Other expounded aspects include reactor design concepts, process monitoring and control, and specific technological barriers thought to hamper the technology’s attempt to achieve commercial success.Validerad;2025;Nivå 2;2025-12-01 (u2);Full text license: CC BY</p
Knowledge ecosystem emergence: Organizing participation, identity, and actorhood to bridge the governance void
No full textMulti-organizational collaborations involving the industry, academia, and government have become prevalent in developing knowledge to address complex societal problems. These fluid and loosely coupled forms of collaboration, known as knowledge ecosystems, provide the necessary organizing elements for the search and creation of new knowledge. While the literature acknowledges the prevalence of knowledge ecosystems, it remains relatively silent on how their organization develops over time. This lacuna in our understanding is problematic, given the challenge of governance voids for cross-sectoral knowledge collaborations, which lead to difficulties in mobilizing action, securing resources, and ultimately achieving the knowledge-related goals of these collaborations. To address this gap, we theorize knowledge ecosystems as meta-organizations, examining how they gradually develop organizing elements that bridge the initial governance void. Empirically, we draw on an in-depth field case study of the High-Capacity Transport ecosystem in Sweden, demonstrating how three interrelated organizational elements—participation, identity, and actorhood—emerge through an iterative, yet broadly sequential process to resolve governance void challenges in resourcing, belonging, and collective action. Furthermore, we identify discursive and performative meta-organizational practices that enable the actors to collectively enact the aforementioned organizational elements and to engage in knowledge search. We further demonstrate how the organization of knowledge ecosystems is never ‘complete’ and the governance void remains only partially resolved, given the underdefined nature of new knowledge as the ecosystem's shared goal. Overall, our process model contributes to the theory, practice, and policy of knowledge ecosystem emergence and organizing. Validerad;2025;Nivå 2;2025-11-25 (u2);Full text: CC BY license;</p
Friction and wear behaviour of fully formulated water-based lubricants under rolling/sliding contacts
No full textThis study evaluates the tribological performance of fully formulated water-based lubricants (WBLs) under rolling/sliding conditions. The WBLs are composed of water-soluble glycols and glycerol with a functional proportion of water. They exhibited significantly lower friction across all lubrication regimes, with near superlubricity achieved under certain conditions. Unlike conventional oils, WBLs showed minimal shear heating effects and exhibited a low shear response with increasing slide-to-roll ratios. Long-duration tests confirmed consistently lower friction for the WBLs. Post-test analysis showed comparable wear between selected WBLs and the reference oil at 40 °C but greater surface modification for WBLs at higher temperatures. Observed wear mechanisms included abrasive and adhesive wear, with occasional instances of spalling after prolonged tests. X-ray photoelectron spectroscopy (XPS) analysis suggested the presence of chemical species on wear scars, attributed to additive-surface interactions. These findings highlight the potential of fully formulated WBLs in rolling/sliding contacts and their current state in comparison to a conventional gear oil.Full text: CC BY license;For funding information, see: https://doi.org/10.1016/j.triboint.2026.111669</p
Vibration reduction in cross-laminated timber panels using various lamination materials and integrated elastomer layers
No full textCross-laminated timber (CLT) is increasingly used for construction of multi-storey buildings. However, ensuring satisfactory vibro-acoustic performance, particularly in the low-frequency range (typically below 200 Hz), remains a significant challenge, often necessitating add-on solutions such as floating floors. In this study, the aim was to investigate how vibration levels for CLT panels can be reduced by using various lamination materials as well as integrated elastomer layers. Finite element (FE) models were developed, calibrated and validated based on experimental modal analysis of CLT panels with and without elastomer layers. Specifically, elastic moduli of spruce, birch and compressed spruce were calibrated to experimentally obtained eigenfrequencies and mode shapes. Moreover, calibrated FE models of selected panels were used to determine and calibrate a viscoelastic material model for the elastomer layer using frequency-dependent stiffnesses and damping. Using the material model for the numerical simulations, the deviations in accelerance root mean square values were less than 1 dB compared to the experimental data. Finally, it was shown that by using birch or compressed spruce instead of spruce the vibration response could be reduced by 30% and 50%, respectively, for a realistic floor panel size. By integrating a 12 mm elastomer layer into the panels, the vibration response could be reduced by an additional 40%, compared to a panel without an elastomer layer.Full text license: CC BY 4.0;Funder: Södra Foundation for Research, Development and Education;</p