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  • Andersson, Jonna
    et al.
    Luleå University of Technology, Department of Health, Education and Technology.
    Giallousis, Reneé
    Luleå University of Technology, Department of Health, Education and Technology.
    Förskollärarens syn på fysisk aktivitet och lärande: Barns möjligheter till fysisk aktivitet i förskolan2024Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien är att analysera förskollärares uppfattningar om fysisk aktivitet och lärande då svenska forskningsstudier visar att förskolebarnen idag rör på sig för lite. Studien har ge- nomförts med hjälp av en kvalitativ forskningsmetod, där tre förskollärare har intervjuats kring deras uppfattningar, medvetenhet och engagemang, samt hur de ser på möjligheterna att skapa en utbildning med fysisk aktivitet som verktyg. Studien har en teoretisk utgångspunkt i det sociokulturella perspektivet och det insamlade materialet har analyserats ur en fenomenogra- fisk analysansats. Resultatet visade att förskollärarna hade kännedom kring betydelsen av rö- relse och fysisk aktivitet och såg kopplingar mellan rörelse och lärande. De uttryckte samtidigt ett behov av förtydliganden i läroplanen att ta stöd av i arbete med fysisk aktivitet. Resultatet visade även, utöver de fördelar fysisk aktivitet har för inlärningsförmågan och den individuella utvecklingen, positiva effekter som förbättringar av gruppdynamiken, samarbetsförmågor och framför allt hur de såg att rörelse kunde förena barn. Därutöver visade resultatet betydelsen av lek, förskollärarnas synsätt, samt möjligheter och hinder som påverkar barnens möjligheter till fysisk aktivitet.

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  • Pettersson, Ida
    et al.
    Luleå University of Technology, Department of Health, Education and Technology.
    Ölund, Emma
    Luleå University of Technology, Department of Health, Education and Technology.
    Inkluderas alla barn i förskolans utbildning och undervisning?2024Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna studie undersöker hur förskollärare uppfattar anpassningen av förskolan för barn i behov av särskilt stöd i undervisningen och om det främjar inkludering i förskoleutbildningen. Utgångspunkten är en kvalitativ forskningsansats, där datainsamlingsmetoden utgår från semistrukturerade intervjuer och från det sociokulturella perspektivet. Informanterna som medverkar i studien är förskollärare från fem olika förskolor. Deras deltagande ger studien en mångfald av perspektiv och erfarenheter från olika pedagogiska verksamheter. Den kvalitativa datan som har framkommit i studien har transkriberats, reducerats och tematiserats. Denna metod bidrar till en rikedom av insikter som resulterar till en fördjupad diskussion om och hur förskollärare kan skapa en stödjande miljö för alla barn, särskilt till de barn som behöver extra stöd för sin utveckling och inkludering. Resultatet av studien visar på flera betydelsefulla aspekter inom förskolepedagogiken. Resultatet visar att samtliga förskollärare betonar vikten av ett nära samarbete med specialpedagog och vårdnadshavare för att skapa en helhetssyn och integrera olika perspektiv i utformningen av lärmiljöer som stödjer varje barn. En central observation är den varierande användningen av tydliggörande pedagogik, vilket indikerar behovet av variation och flexibilitet för att möta individuella behov och samtidigt främja inkludering. Slutsatsen av detta indikerar på att denna variation speglar det komplexa kravet på att balansera hänsynen till varje barns unika behov samtidigt som en inkluderande lärmiljö skapas. Genom att utgå från det sociokulturella perspektivet som betonar kommunikation och samspel, ger det studien en ram för att förstå hur förskollärare tillämpar tydliggörande pedagogik för att stärka kommunikation och samspel. 

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  • Johansson, Emmy
    et al.
    Luleå University of Technology, Department of Health, Education and Technology.
    Mattsson, Hanna
    Luleå University of Technology, Department of Health, Education and Technology.
    ”Vi behöver släcka bränder”: En kvalitativ intervjustudie om specialpedagogiska resursers påverkan för en likvärdig förskola för alla barn2024Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien är att synliggöra förskollärares uppfattningar gällande hur behovet av specialpedagogiska resurser möts upp i verksamheten. Studien syftar även till att synliggöra och analysera hur förskolans tillgång till specialpedagogiska resurser påverkar likvärdigheten samt vilka konsekvenser uteblivna resurser kan resultera i. Studien utgår från en kvalitativ forskningsansats där semistrukturerade intervjuer använts som datainsamlingsmetod. Intervjuerna har genomförts med totalt fem förskollärare från tre olika kommuner. De teoretiska perspektiv som varit utgångspunkt för studien är fenomenografin och det sociokulturella perspektivet. Det insamlade materialet har bearbetats med utgångspunkt i en fenomenografisk analysmetod där resultatet diskuterats i relation till det sociokulturella perspektivet samt tidigare forskning. Studiens resultat visar att specialpedagogiska resurser är av avgörande betydelse för att skapa en likvärdig förskola för alla barn. Resultatet visar också att det, enligt förskollärarna i studien, råder stor brist på tillgängliga resurser och att detta många gånger grundar sig i bristande gehör från huvudmannen samt ekonomiska förutsättningar. De slutsatser som dragits utifrån studiens resultat är att specialpedagogiska resurser behöver finnas tillgängliga i större utsträckning, att huvudmannen behöver förbättra arbetet med resursfördelningen för att möta upp verksamheternas behov samt att det är av stor vikt att arbeta förebyggande i hela barngruppen för att kompensera för de bristfälliga resurserna.

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  • Somero, Alva
    Luleå University of Technology, Department of Health, Education and Technology.
    Förskolans uppgift att främja barns hälsa: Förskollärarens implementering av, och syn på, det hälsofrämjande arbetet2024Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna studie syftar till att öka kunskap om förskollärares implementering av, och syn på, det hälsofrämjande arbetet i förskolans verksamhet. Studien tar avstamp i det sociokulturella- och salutogena perspektivet. För att besvara studiens syfte och forskningsfrågor har semistrukturerade intervjuer använts, dessa har spelats in, transkriberats och bearbetatsgenom en tematisk analys. Resultatet visar att det hälsofrämjande arbetet innefattar att barnen erbjuds en välavvägd dygnsrytm, i vilket god omsorg, trygghet, relationsskapande, rörelse, lek samt meningsfull aktivitet inryms. Resultatet visar på hur förskollärarna arbetar aktivt med att planera och organisera verksamheten för att kunna möjliggöra detta. Bristen på dialog och olika förhållningssätt anses vara faktorer som försvårar det gemensamma arbetet. Likaså beskrivs personalfrånvaro, stress, socioekonomiska faktorer, barns hemmiljö och antal barn i barngruppen som hinder i det hälsofrämjande arbetet. Studiens resultat indikerar på vikten av att främja en likvärdig förskola och att förskolan ska vara en plats där barns upplevelse av begriplighet, hanterbarhet och meningsfullhet stärks. Slutsatserna riktar sig mot att utforma en förskola som främjar barns upplevelse av detta, där relationsskapande är ett grundfundament. Genom att använda sig av scaffolding och genom att utgå från barns proximala utvecklingszon främjas barns lärande ochutveckling, hälsa och välbefinnande. Genom att förskolläraren bär en medvetenhet för detta, en vilja att utvecklas och söka efter ny kunskap, blir förskolan en plats där barns hälsa och välbefinnande främjas.

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  • Prajapati, Deepak K.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Hansen, Jonny
    Electric Propulsion Development, Scania CV AB, Södertälje, Sweden.
    Björling, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    An assessment of the effect of surface topography on coefficient of friction for lubricated non-conformal contacts2024In: Frontiers in Mechanical Engineering, E-ISSN 2297-3079, Vol. 10, article id 1360023Article in journal (Refereed)
    Abstract [en]

    Determining an accurate state of lubrication is of utmost importance for the precise functionality of machine elements and to achieve elongated life and durability. In this work, a homogenized mixed-lubrication model is developed to study the effect of surface topographies on the coefficient of friction. Various measured real surface topographies are integrated in the model using the roughness homogenization method. The shear-thinning behavior of the lubricant is incorporated by employing the Eyring constitutive relation. Several Stribeck curves are generated to analyze the effect of roughness lays and root mean square (RMS) roughness on the coefficient of friction. The homogenized mixed lubrication model is validated against experimental rolling/sliding ball-on-disc results, and a good agreement between simulated and experimental coefficient of friction is found.

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  • Mahmud, Tanjim
    et al.
    Department of Computer Science and Engineering, Rangamati Science and Technology University, Rangamati, 4500, Bangladesh.
    Barua, Koushick
    Department of Computer Science and Engineering, Rangamati Science and Technology University, Rangamati, 4500, Bangladesh.
    Habiba, Sultana Umme
    Department of Computer Science and Engineering, Khulna University of Engineering & Technology, Khulna, 9203, Bangladesh.
    Sharmen, Nahed
    Department of Obstetrics and Gynecology, Chattogram Maa-O-Shishu Hospital Medical College, Chittagong, 4100, Bangladesh.
    Hossain, Mohammad Shahadat
    Department of Computer Science and Engineering, University of Chittagong, Chittagong 4331, Bangladesh.
    Andersson, Karl
    Pervasive and Mobile Computing Laboratory, Luleå University of Technology, Luleå, 97187, Sweden.
    An Explainable AI Paradigm for Alzheimer’s Diagnosis Using Deep Transfer Learning2024In: Diagnostics, ISSN 2075-4418, Vol. 14, no 3, article id 345Article in journal (Refereed)
    Abstract [en]

    Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that affects millions of individuals worldwide, causing severe cognitive decline and memory impairment. The early and accurate diagnosis of AD is crucial for effective intervention and disease management. In recent years, deep learning techniques have shown promising results in medical image analysis, including AD diagnosis from neuroimaging data. However, the lack of interpretability in deep learning models hinders their adoption in clinical settings, where explainability is essential for gaining trust and acceptance from healthcare professionals. In this study, we propose an explainable AI (XAI)-based approach for the diagnosis of Alzheimer’s disease, leveraging the power of deep transfer learning and ensemble modeling. The proposed framework aims to enhance the interpretability of deep learning models by incorporating XAI techniques, allowing clinicians to understand the decision-making process and providing valuable insights into disease diagnosis. By leveraging popular pre-trained convolutional neural networks (CNNs) such as VGG16, VGG19, DenseNet169, and DenseNet201, we conducted extensive experiments to evaluate their individual performances on a comprehensive dataset. The proposed ensembles, Ensemble-1 (VGG16 and VGG19) and Ensemble-2 (DenseNet169 and DenseNet201), demonstrated superior accuracy, precision, recall, and F1 scores compared to individual models, reaching up to 95%. In order to enhance interpretability and transparency in Alzheimer’s diagnosis, we introduced a novel model achieving an impressive accuracy of 96%. This model incorporates explainable AI techniques, including saliency maps and grad-CAM (gradient-weighted class activation mapping). The integration of these techniques not only contributes to the model’s exceptional accuracy but also provides clinicians and researchers with visual insights into the neural regions influencing the diagnosis. Our findings showcase the potential of combining deep transfer learning with explainable AI in the realm of Alzheimer’s disease diagnosis, paving the way for more interpretable and clinically relevant AI models in healthcare.

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  • Soleimani-Chamkhorami, Khosro
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Department of Mathematics, Faculty of Computer Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran.
    Garmabaki, Amir Soleimani
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kasraei, Ahmad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Department of Civil, Environmental, and Natural Resources Engineering, Division of Operation and Maintenance, Luleå University of Technology, SE-97187 Luleå, Sweden.
    Famurewa, Stephen Mayowa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Swedish Transport Administration, Luleå, Sweden.
    Odelius, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Strandberg, Gustav
    Rossby Centre, Swedish Meteorological and Hydrological Institute, SMHI, Sweden.
    Life cycle cost assessment of railways infrastructure asset under climate change impacts2024In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 127, article id 104072Article in journal (Refereed)
    Abstract [en]

    Climate change impacts such as extreme temperatures, snow and ice, flooding, and sea level rise posed significant threats to railway infrastructure networks. One of the important questions that infrastructure managers need to answer is, “How will maintenance costs be affected due to climate change in different climate change scenarios?” This paper proposes an approach to estimate the implication of climate change on the life cycle cost (LCC) of railways infrastructure assets. The proportional hazard model is employed to capture the dynamic effects of climate change on reliability parameters and LCC of railway assets. A use-case from a railway in North Sweden is analyzed to validate the proposed process using data collected over 18 years. The results have shown that precipitation, temperature, and humidity are significant weather factors in selected use-case. Furthermore, our analyses show that LCC under future climate scenarios will be about 11 % higher than LCC without climate impacts.

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  • Khan, Majid
    et al.
    Civil Engineering Department, COMSATS University Islamabad, Abbottabad Campus, 22060, Pakistan.
    Nassar, Roz-Ud-Din
    Department of Civil and Infrastructure Engineering at American University of Ras Al Khaimah, United Arab Emirates.
    Anwar, Waqar
    Department of Civil and Environmental Engineering, University of New Hampshire, Durham, NH 03824, USA.
    Rasheed, Mazhar
    College of Engineering and Technology, University of Sargodha, 40100, Pakistan.
    Najeh, Taoufik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Gamil, Yaser
    Department of Civil Engineering, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, 47500 Bandar Sunway, Selangor, Malaysia.
    Farooq, Furqan
    NUST Institute of Civil Engineering (NICE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Sector H-12, Islamabad, 44000, Pakistan; Military Engineer Service (MES), Ministry of Defence (MoD), Rawalpindi, 43600, Pakistan.
    Forecasting the strength of graphene nanoparticles-reinforced cementitious composites using ensemble learning algorithms2024In: Results in Engineering (RINENG), ISSN 2590-1230, Vol. 21, article id 101837Article in journal (Refereed)
    Abstract [en]

    Integrating nanomaterials into concrete is a promising solution to improve concrete strength and durability. However, the intricacies of such nanoscale cementitious composites are highly complex. Traditional regression models encounter limitations in capturing these intricate compositions to provide accurate and reliable estimations. This study focuses on developing robust prediction models for the compressive strength (CS) of graphene nanoparticle-reinforced cementitious composites (GrNCC) through machine learning (ML) algorithms. Three ML models, bagging regressor (BR), decision tree (DT), and AdaBoost regressor (AR), were employed to predict CS based on a comprehensive dataset of 172 experimental values. Seven input parameters, including graphite nanoparticle (GrN) diameter, water-to-cement ratio (wc), GrN content (GC), ultrasonication (US), sand content (SC), curing age (CA), and GrN thickness (GT), were considered. The models were trained with 70 % of the data, and the remaining 30 % of the data was used for testing the models. Statistical metrics such as mean absolute error (MAE), root mean square error (RMSE) and correlation coefficient (R) were employed to assess the predictive accuracy of the models. The DT and AR models demonstrated exceptional accuracy, yielding high correlation coefficients of 0.983 and 0.979 for training, and 0.873 and 0.822 for testing, respectively. Shapley Additive exPlanation (SHAP) analysis highlighted the influential role of curing age and GrN thickness (GT), positively impacting CS, while an increased water-to-cement ratio (w/c) negatively affected CS. This study showcases the efficacy of ML techniques in accurately predicting CS of graphene nanoparticle-modified concrete, offering a swift and cost-effective approach for assessing nanomaterial impact on concrete strength and reducing reliance on time-consuming and expensive experiments.

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  • Al-Idani, Mona
    et al.
    Luleå University of Technology, Department of Health, Education and Technology.
    Kudus, Sinit
    Luleå University of Technology, Department of Health, Education and Technology.
    Betydelsen av artificiell intelligens inom mammografiscreening: En litteraturstudie2024Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Inledning: Bröstcancer är den vanligaste cancersjukdomen bland kvinnor i Sverige. I Sverige erbjuds alla kvinnor i åldern 40 och 75 år regelbundna hälsokontroller med mammografiscreening. Dagens screeningverktyg för bröstcancer har en känslighet på 87 procent att upptäcka bröstcancer och de övriga 13 procent upptäcks inte vid mammografiscreening. Artificiell intelligens (AI) inom bröstcancerscreening kan bidra till säkrare bilddiagnostisk och minskar dödlighet i bröstcancer. Genom att röntgensjuksköterskor följer utvecklingen och får ökad förståelse för AI:s effekter inom mammografiscreening så kommer detta att bidra till fortsatt evidensbaserad vård. Syfte: Syftet med denna studie var att belysa AI:s effekter inom mammografiscreening. Metod: Denna studie genomfördes som en allmänlitteraturöversikt enligt Fribergs (2017) tillvägagångssätt och beskrivning. Artikelsökningen gjordes i databaserna PubMed och CINAHL resulterade i 14 artiklar som svarade på studiens syfte. Resultat: Resultatet av studien visar att AI kan minska antalet falska positiva och falska negativa svar. AI kan klassificera bröstvävnaden och urskilja maligna förkalkningar från benigna. Genom att AI används som stödverktyg under dubbelgranskning kan radiologerna upptäcka bröstcancer tidigare hos fler kvinnor. Röntgensjuksköterskornas arbetsbelastning kommer att minska i takt med minskat antal falskt positiva svar. Slutsats: Denna studie visade på flera positiva effekter av AI som ett verktyg inom mammografiscreening. Minskning av falskt positiva svar skapar förutsättningar för färre antal oroliga kvinnor i samband med undersökningarna. Minskning av falskt negativa svar kommer att öka tidig upptäckt av bröstcancer. Tidig upptäckt av bröstcancer minskar därmed dödligheten i sjukdomen, vilket är till patientnytta. AI kommer även bidra till förbättrat arbetsflöde, minskad psykisk påfrestning och därmed minskad utbrändhet för röntgensjuksköterskor. Genom att röntgensjuksköterskan uppdaterar sig kring den utveckling som sker i vården så kan detta medföra förbättrad vård, vilket i sin tur leder till säkrare och effektivare vård i samhället (SFR, 2012). 

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  • Wästerlid, Cecilia
    et al.
    RISE Research Institutes of Sweden, Stockholm and Mölndal, Sweden .
    Rahnama, Hossein
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Humans and Technology.
    Ström, Mikael
    RISE Research Institutes of Sweden, Stockholm and Mölndal, Sweden.
    Abrahamsson, Lena
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Humans and Technology.
    Öhrvall Rönnbäck, Anna
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Humans and Technology.
    Jönsson, Christina
    RISE Research Institutes of Sweden, Stockholm and Mölndal, Sweden.
    The Table & Swirl Method: A Quick Visualization Methodfor Aspects of Circular Material Streams2023Report (Other academic)
    Abstract [en]

    This document describes the Table & Swirl method, which is a quick visualization method for aspects of circular material streams. Use the method to structure and visualize information to understand and share aspects of material streams in a circular economy. It is a time efficient way to start interesting discussions on any topic related to a circular material stream. The method is built around the Table, a tool to in a structured way gather information and the Swirl, which provides quick visualization.

    The feedback from our test workshops and end-users were: • ”An eye opener!” • ”First, I thought the model was too simple, then I realized how quickly we got into interesting discussions.”

    This method was developed in the year 2023 by the Research Institute of Sweden (RISE) and Luleå University of Technology (LTU) in the joint project “Feasibility study: Five circular material streams for batteries“, which was financed by Energimyndigheten, the Swedish Energy Agency.

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  • Bennheden, Daniel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Ärendehantering genom maskininlärning2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates how artificial intelligence can be used to automatically categorize faultreports that are processed in a case management system by using machine learning and techniquessuch as text mining. The study is based on Design Science Research Methodology and Peffer's sixsteps of design methodology, which in addition to design of an artifact concerns requirements andevaluation. The machine learning models that were developed were trained on historical data fromthe case management system Infracontrol Online, using four types of algorithms, Naive Bayes,Support Vector Machine, Neural Network, and Random Forest. A web application was developed todemonstrate how one of the machine learning models trained works and can be used to categorizetext. Regular users of the system have then had the opportunity to test the performance of themodel and evaluate how it works by marking where it categorizes text prompts correctly.The results show that it is possible to solve the task using machine learning. A crucial part of thedevelopment was the selection of data used to train the model. Different customers using thesystem use it in different ways, which made it advantageous to separate them and train models fordifferent customers independently. Another source of inconsistent results is how organizationschange their processes and thus case management over time. This issue was addressed by limitinghow far back in time the model retrieves data for training. The two strategies for solving the issuesmentioned have the disadvantage that the amount of historical data available for training decreases,but the results do not show any clear disadvantage for the machine learning models trained onsmaller data sets. They perform well and tests show an acceptable level of accuracy for theirpredictions

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  • Malmqvist, Rasmus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Virtual Test Cell: a Real-Time digital twin of an internal combustion engine2024Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As the world is evolving faster and technology gets cheaper and more powerful, simulations are proving to be more and more beneficial. Simulations allow for faster development with less lead time between iterations which means that product versions can be released more often and at less cost.

    The automotive industry is heavily affected by emission legislation and environmental politics. The development of more environmentally friendly engines forces the rate of development to speed up. Simulations allow the industry to keep up with the increasing requests for more complex systems.

    For software development, it speeds up the process significantly. Although real-life testing in engine test cells and test cars still sets the foundation for and validates the results of the simulations, simulations can drastically decrease the amount needed. Less unnecessary real-life testing with bugs in the software causing wasted time and cost. In the meantime, more iterations can be tested in a smaller time frame, making the actual real-life testing more valuable and giving.

    The aim of this thesis is to develop a method to convert an accurate but relatively slow simulation model of the airflow through an engine, into a faster-running format preparing it to run in close to Real-Time and with a fixed timestep. Then exporting the converted model as a functional mock-up unit, FMU, a standardised entity, part of the Functional Mock-up Interface standard. The FMU was to be used in Software in Loop, SiL, simulations using it in cooperation with Matlab Simulink and Synopsys Silver. The SiL environment is then to be used to develop and test calibration software for the engine in question. 

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  • Dhakal, Nayan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. Institute of Functional Surfaces, School of Mechanical Engineering, University of Leeds, LS2 9JT Leeds, United Kingdom.
    Espejo, Cayetano
    Institute of Functional Surfaces, School of Mechanical Engineering, University of Leeds, LS2 9JT Leeds, United Kingdom.
    Morina, Ardian
    Institute of Functional Surfaces, School of Mechanical Engineering, University of Leeds, LS2 9JT Leeds, United Kingdom.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tribological performance of 3D printed neat and carbon fiber reinforced PEEK composites2024In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 193, article id 109356Article in journal (Refereed)
    Abstract [en]

    This work investigates the tribological behavior of neat and carbon fiber-reinforced polyether-ether-ketone (PEEK) materials processed using the fused filament fabrication (FFF) technique. The reciprocating sliding behavior of printed polymers against stainless steel (SS) under dry and water-lubricated conditions was studied. The running-in behavior and evolution of friction were dependent on the material combination and sliding conditions. PEEK reinforced with 10 wt% carbon fibers was optimal considering tribological performance. Neat PEEK exhibited a combination of abrasive and adhesive wear mechanisms, while composites primarily showed fiber-matrix debonding and delamination during sliding. The outcome of this work has significance in improving the processing design of PEEK-based materials in extrusion-based 3D printing for tribological applications.

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  • Björk, Oscar
    Luleå University of Technology, Department of Health, Education and Technology, Education, Language, and Teaching.
    Writing and Power: Conceptualising Early School Writing Instruction from a Critical Discourse Analytical Perspective2024In: L1-Educational Studies in Language and Literature, ISSN 1567-6617, E-ISSN 1573-1731, Vol. 24, no 1, p. 1-30Article in journal (Refereed)
    Abstract [en]

    The primary aim of this theoretical and methodological paper is to conceptualise early school writing instruction (with 6 and 7-year-old students) through a critical discourse analytical (CDA; Fairclough, 2003) perspective. By drawing on empirical examples from two L1 classrooms, the paper provides an example of how a CDA analysis may be operationalised, particularly in an educational setting in primary school years. In doing so, the paper unveils how social power permeates the discourse practices of early school writing and how its effects on writing instruction may be understood. The data consists of video-recorded observations of writing instruction in two classrooms and transcribed semi-structured interviews with two teachers. The conceptualisation shows major differences in the effects of power in discourse in the two classrooms, shaping the discourse practice in various ways. It furthermore becomes evident that these classrooms are sites of power struggles with effects on discourse and where discourse practices, in various ways, (re)construe both the social world of the classroom as well as what is being taught. However, rather than reproducing social power structures per se, this paper suggests that the classroom holds potential for contestation and transformation of structural power, not least dependent on the actions of the teacher. 

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  • Swain, Sidhartha Sekhar
    et al.
    Division of Agricultural Engineering, ICAR-Indian Agricultural Research Institute, 110012, New Delhi, India.
    Khura, Tapan Kumar
    Division of Agricultural Engineering, ICAR-Indian Agricultural Research Institute, 110012, New Delhi, India.
    Sahoo, Pramod Kumar
    Division of Agricultural Engineering, ICAR-Indian Agricultural Research Institute, 110012, New Delhi, India.
    Chobhe, Kapil Atmaram
    Division of Soil Science and Agricultural Chemistry, ICAR-Indian Agricultural Research Institute, 110012, New Delhi, India.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kushwaha, Hari Lal
    Division of Agricultural Engineering, ICAR-Indian Agricultural Research Institute, 110012, New Delhi, India.
    Kushwaha, Nand Lal
    Division of Agricultural Engineering, ICAR-Indian Agricultural Research Institute, 110012, New Delhi, India.
    Panda, Kanhu Charan
    Department of Soil Conservation, National PG College (Barhalganj), DDU Gorakhpur University, 273402, Gorakhpur, UP, India.
    Lande, Satish Devram
    Division of Agricultural Engineering, ICAR-Indian Agricultural Research Institute, 110012, New Delhi, India.
    Singh, Chandu
    Division of Genetics, ICAR-Indian Agricultural Research Institute, 110012, New Delhi, India.
    Proportional impact prediction model of coating material on nitrate leaching of slow-release Urea Super Granules (USG) using machine learning and RSM technique2024In: Scientific Reports, E-ISSN 2045-2322, Vol. 14, no 1, article id 3053Article in journal (Refereed)
    Abstract [en]

    An accurate assessment of nitrate leaching is important for efficient fertiliser utilisation and groundwater pollution reduction. However, past studies could not efficiently model nitrate leaching due to utilisation of conventional algorithms. To address the issue, the current research employed advanced machine learning algorithms, viz., Support Vector Machine, Artificial Neural Network, Random Forest, M5 Tree (M5P), Reduced Error Pruning Tree (REPTree) and Response Surface Methodology (RSM) to predict and optimize nitrate leaching. In this study, Urea Super Granules (USG) with three different coatings were used for the experiment in the soil columns, containing 1 kg soil with fertiliser placed in between. Statistical parameters, namely correlation coefficient, Mean Absolute Error, Willmott index, Root Mean Square Error and Nash–Sutcliffe efficiency were used to evaluate the performance of the ML techniques. In addition, a comparison was made in the test set among the machine learning models in which, RSM outperformed the rest of the models irrespective of coating type. Neem oil/ Acacia oil(ml): clay/sulfer (g): age (days) for minimum nitrate leaching was found to be 2.61: 1.67: 2.4 for coating of USG with bentonite clay and neem oil without heating, 2.18: 2: 1 for bentonite clay and neem oil with heating and 1.69: 1.64: 2.18 for coating USG with sulfer and acacia oil. The research would provide guidelines to researchers and policymakers to select the appropriate tool for precise prediction of nitrate leaching, which would optimise the yield and the benefit–cost ratio.

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  • Lundmark, Robert
    et al.
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Social Sciences.
    Wetterlund, Elisabeth
    Olofsson, Elias
    Swedish Agency for Economic and Regional Growth, Box 4044, SE-102 61 Stockholm, Sweden.
    On the green transformation of the iron and steel industry: Market and competition aspects of hydrogen and biomass options2024In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 182, article id 107100Article in journal (Refereed)
    Abstract [en]

    The iron and steel industry is a major emitter of carbon dioxide globally. To reduce their carbon footprint, the iron and steel industry pursue different decarbonization strategies, including deploying bio-based materials and energy carriers for reduction, carburisation and/or energy purposes along their value-chains. In this study two potential roles for biomass were analysed: (a) substituting for fossil fuels in iron-ore pellets induration and (b) carburisation of DRI (direct reduced iron) produced via fully hydrogen-based reduction. The purpose of the study was to analyse the regional demand-driven price and allocative effects of biomass assortments under different biomass demand scenarios for the Swedish iron and steel industry. Economic modelling was used in combination with spatial biomass supply assessments to predict the changes on relevant biomass markets. The results showed that the estimated demand increases for forest biomass will have significant regional price effects. Depending on scenario, the biomass demand will increase up to 25 percent, causing regional prices to more than doubling. In general, the magnitude of the price effects was driven by the volumes and types of biomasses needed in the different scenarios, with larger price effects for harvesting residues and industrial by-products compared to those of roundwood. A small price effect of roundwood means that the incentives for forest-owners to increase their harvests, and thus also the availability of harvest residues, are small. Flexibility in the feedstock sourcing (both regarding quality and geographic origin) will thus be important if forest biomass is to satisfy demands in iron and steel industry.

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  • Strandberg, Anna
    et al.
    Umeå University, Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory, SE 901 87 Umeå, Sweden; Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE 901 83 Umeå, Sweden.
    Thyrel, Mikael
    Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE 901 83 Umeå, Sweden.
    Falk, Joel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Skoglund, Nils
    Umeå University, Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory, SE 901 87 Umeå, Sweden.
    Morphology and phosphate distribution in bottom ash particles from fixed-bed co-combustion of sewage sludge and two agricultural residues2024In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 177, p. 56-65Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to provide detailed knowledge of the morphological properties of ash particles, including the volumetric fractions and 3D distributions of phosphates that lay within them. The ash particles came from digested sewage sludge co-combusted with K- and Si-rich wheat straw or K-rich sunflower husks. X-ray micro-tomography were combined with elemental composition and crystalline phase information to analyse the ash particles in 3D.

    Analyses of differences in the X-ray attenuation enabled calculation of 3D phosphate distributions that showed high heterogeneity in the slag particles. This is underscored by a distinct absence of phosphates in iron-rich and silicon-rich parts. The slag from silicate-based wheat straw mixtures had lower average attenuation than that from sunflower husks mixtures, which contained more calcium. Calculated shares of phosphates between 7 and 17 vol% were obtained, where the highest value for a single assigned phosphate was observed in hard slag from wheat straw with 10 % sewage sludge. The porosity was notably higher for particles from pure wheat straw combustion (62 vol%), compared to the other samples (15–35 vol%). A high open pore volume fraction (60–97 vol%) indicates that a large part of the pores can be accessed by the surroundings. For all samples, more than 60 % of the discrete (closed) pores had an equivalent diameter < 30 μm, while the largest volume fraction consisted of pores with an equivalent diameter > 75 μm. Slag from sunflower husk mixtures had larger pore volumes and a greater relative number of discrete pores >75 µm compared to wheat straw mixtures.

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  • Li, Weihua
    et al.
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Wang, Xiaohan
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Lin, Jishuai
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Meng, Xiangyong
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Wang, Lihua
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Wang, Maorong
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Jing, Qiang
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Song, Yang
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice Via Torino 155, 30172 Venezia Mestre, Italy.
    Zhao, Haiguang
    College of Textiles and Clothes, State Key Laboratory of Bio-Fibers and Eco-Textiles, College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P.R. China.
    Controllable and large-scale synthesis of carbon quantum dots for efficient solid-state optical devices2024In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 122, article id 109289Article in journal (Refereed)
    Abstract [en]

    Carbon quantum dots (C-dots) showed excellent structure-tunable optical properties, mainly composed of carbon, nitrogen and oxygen. They have been used for various types of solid-state optical devices. Due to the photoluminescence quenching caused by aggregation, it is a challenge to produce high quantum yield and large Stokes shift C-dots via controllable and simple approaches. In this work, we demonstrated a microwave assisted heating approach for the high-quality C-dots production with ten grams scale per batch in less than 4 min. The addition of metal cation promoted the formation of the foam-structure by forming carboxyl-metal-amine complex, enabling the spatial confined growth of the C-dots in a solid-state, contributing to the high quantum yield (QY) of 73% with a Stokes shift of 0.65 eV. By tuning the structure of the C-dots, excitation dependent and independent photoluminescent (PL) behavior were achieved because of the formation of the different types of energy states evidenced by transient PL and femtosecond transient absorption spectroscopy. These optical properties enable the C-dots to be successfully integrated in luminescent solar concentrators (LSCs), having an external optical efficiency of 3.0% and a power conversion efficiency of 1.3% (225 cm2) and an excitation-dependent high-level anticounterfeiting fluorescent code, showing a great potential for solid-state optical system.

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  • Fan, Jing
    et al.
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Dai, Zhengxing
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Cao, Jian
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Mu, Liwen
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Lu, Xiaohua
    State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
    Hybrid data-driven and physics-based modeling for viscosity prediction of ionic liquids2024In: Green Energy & Environment, E-ISSN 2468-0257Article in journal (Refereed)
    Abstract [en]

    Viscosity is one of the most important fundamental properties of fluids. However, accurate acquisition of viscosity for ionic liquids (ILs) remains a critical challenge. In this study, an approach integrating prior physical knowledge into the machine learning (ML) model was proposed to predict the viscosity reliably. The method was based on 16 quantum chemical descriptors determined from the first principles calculations and used as the input of the ML models to represent the size, structure, and interactions of the ILs. Three strategies based on the residuals of the COSMO-RS model were created as the output of ML, where the strategy directly using experimental data was also studied for comparison. The performance of six ML algorithms was compared in all strategies, and the CatBoost model was identified as the optimal one. The strategies employing the relative deviations were superior to that using the absolute deviation, and the relative ratio revealed the systematic prediction error of the COSMO-RS model. The CatBoost model based on the relative ratio achieved the highest prediction accuracy on the test set (R2 = 0.9999, MAE = 0.0325), reducing the average absolute relative deviation (AARD) in modeling from 52.45 % to 1.54 %. Features importance analysis indicated the average energy correction, solvation-free energy, and polarity moment were the key influencing the systematic deviation.

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  • Johansson, Kim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Carabante, Ivan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Immobilisation of arsenic in contaminated soil by electrokinetics in an outdoor experiment2024In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 918, article id 170656Article in journal (Refereed)
    Abstract [en]

    Although landfilling is environmentally and economically unsustainable, it is the dominant soil remediation method in EU member states. This paper describes part of a study on mixed contaminants that investigated the stabilisation of arsenic (As) in contaminated soil in an outdoor box experiment with electrokinetic treatment (EK). The experiment was conducted in two 1 m3 boxes, each containing a 20 cm bottom layer of sand, overlaid with 20 cm of peat. In EK, a pulsating, low-voltage current was applied with the intention of corroding the zerovalent iron (Fe) electrodes, migrating ionic Fe species, and forming secondary iron minerals, thereby immobilizing As. Porewater samples were collected over two seasons to determine whether the treatment decreased the concentration of dissolved As. Sequential extraction was performed on the soil samples to determine whether the fraction of Fe-bound As increased. Reed canary grass was planted in one of the boxes during the second season and analysed for As uptake. The results showed that the treatment decreased the porewater As concentration in sand by 50–54 %, while the concentration of Fe increased. The sequential extraction of sand showed that the fraction of As bound to poorly crystalline Fe oxides increased during this time. This treatment effect was less visible in the peat. Moreover, the exchangeable As fraction increased in both peat and sand, most likely because of the decrease in redox potential at the end of the experiment. The plants grown in treated soil accumulated less As than those grown in untreated soil, indicating that the phytoavailable As fraction decreased. This study showed that EK remediation can be a suitable in situ remediation technique, mostly in sand. Future research should focus on redox control to further optimise EK remediation and ensure long-term As stability in treated soils.

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  • Liu, Ye
    et al.
    School of Materials Science and Engineering, Xiangtan University, 411105 Xiangtan, China.
    Lin, Zunmin
    School of Materials Science and Engineering, Xiangtan University, 411105 Xiangtan, China.
    He, Shuang
    School of Materials Science and Engineering, Xiangtan University, 411105 Xiangtan, China.
    Zhang, Lin
    Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, 100083, Beijing, China; Institute of Materials Intelligent Technology, Liaoning Academy of Materials, 110004 Shenyang, China.
    Chen, Xu
    School of Materials Science and Engineering, Xiangtan University, 411105 Xiangtan, China.
    Tan, Qiankun
    School of Materials Science and Engineering, Xiangtan University, 411105 Xiangtan, China.
    Gorbatov, Oleg I.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Peng, Ping
    School of Materials Science and Engineering, Hunan University, 410082 Changsha, China.
    Qu, Xuanhui
    Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, 100083, Beijing, China.
    First-principles investigation on the thermodynamic and mechanical properties of Y4Zr3O12 and Y2Ti2O7 oxides in ferritic alloy under helium environment2024In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 29, p. 1872-1886Article in journal (Refereed)
    Abstract [en]

    This study investigates the thermodynamic and mechanical properties of Y4Zr3O12 and Y2Ti2O7 oxides in ferritic alloys with and without Helium utilizing a systematic first-principles approach. Firstly, the atomic arrangement of Y and Zr atoms at cation 18f sites in δ-(Y–Zr–O) oxide is identified, while it is found that Y4Zr3O12 exhibits a more robust formation tendency than Y2Ti2O7. Furthermore, it is noted that both Y4Zr3O12 and Y2Ti2O7 oxides demonstrate a prior ability to trap Helium compared to the bcc-Fe matrix, which leads to a substantial enhancement on the stiffness of both oxides. The elastic moduli of both Y4Zr3O12 and Y2Ti2O7 oxide exhibit a gradual increase with the growing Helium concentration. As a result, the enhanced shear modulus of oxides and sustained shear modulus of the bcc-Fe matrix collectively contribute to the overall strength of ferritic alloys under Helium environments. The findings in this work propose valuable insights for guiding critical strategies in the design of high-performance oxide-dispersion-strengthened ferritic alloys, particularly for applications in Helium environments.

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  • Hauashdh, Ali
    et al.
    Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein Onn Malaysia, Batu Pahat, Johor, 86400, Malaysia.
    Nagapan, Sasitharan
    Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein Onn Malaysia, Batu Pahat, Johor, 86400, Malaysia; Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, India.
    Jailani, Junaidah
    Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein Onn Malaysia, Batu Pahat, Johor, 86400, Malaysia.
    Gamil, Yaser
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Department of Civil Engineering, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, 47500 Bandar Sunway, Selangor, Malaysia .
    An integrated framework for sustainable and efficient building maintenance operations aligning with climate change, SDGs, and emerging technology2024In: Results in Engineering (RINENG), ISSN 2590-1230, Vol. 21, article id 101822Article in journal (Refereed)
    Abstract [en]

    While existing literature offers various frameworks, they primarily focus on traditional building maintenance procedures and overlook the importance of integrating sustainability, climate change, environmental factors, and emerging technologies. To address this gap, this research has developed a comprehensive framework that caters to current needs, challenges, and future priorities. The integrated framework for building maintenance operations aligns with the Sustainable Development Goals (SDGs), climate change mitigation and adaptation, the adoption of emerging technology, energy conservation, as well as safety, resilience, and effectiveness. The development of the framework encompassed four phases: pre-development phases 1 and 2, development phase 3, and validation phase 4. During this process, current issues and challenges were identified, impacts were assessed, and strategies were developed. The framework serves as a roadmap to address these challenges and requirements in future building maintenance operations, making significant contributions to all three dimensions of sustainability: environmental, social, and economic. In summary, this study offers a comprehensive and in-depth analysis of the current issues, challenges, and potential improvements and benefits in building maintenance operations, providing a practical guide for industry stakeholders and making a significant contribution to the existing body of knowledge.

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  • Abuhussain, Mohammed Awad
    et al.
    Architectural Engineering Department, College of Engineering, Najran University, Najran, Saudi Arabia.
    Ahmad, Ayaz
    Department of Civil Engineering, COMSATS University Islamabad, Abbottabad 22060, Pakistan.
    Amin, Muhammad Nasir
    Department of Civil and Environmental Engineering, College of Engineering, King Faisal University, Al-Ahsa 31982, Saudi Arabia.
    Althoey, Fadi
    Department of Civil Engineering, College of Engineering, Najran University, Najran, Saudi Arabia.
    Gamil, Yaser
    Department of Civil Engineering, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, 47500 Bandar Sunway, Selangor, Malaysia.
    Najeh, Taoufik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Data-driven approaches for strength prediction of alkali-activated composites2024In: Case Studies in Construction Materials, E-ISSN 2214-5095, Vol. 20, article id e02920Article in journal (Refereed)
    Abstract [en]

    Alkali-activated composites (AACs) have attracted considerable interest as a promising alternative to reduce CO2 emissions from Portland cement production and advance the decarbonisation of concrete construction. This study describes the data-driven predictive modelling to anticipate the compressive strength (CS) of AACs. Four different modelling techniques have been chosen to forecast the CS of AACs using the selected data set. The decision tree (DT), multi-layer perceptron (MLP), bagging regressor (BR), and AdaBoost regressor (AR) were employed to investigate the precision level of each model. When it comes to predicting the CS of AACs, the results show that the AR model performs better than the BR model, the MLP model, and the DT model by providing a higher value for the coefficient of determination, which is equal to 0.91, and a lower MAPE value, which is equal to 13.35%. However, the accuracy level of the BR model was very near to that of the AR model, with the R2 value suggesting a value of 0.90 and the MAPE value indicating a value of 14.43%. Moreover, the graphical user interface has also been developed for the strength prediction of alkali-activated composites, making it easy to get the required output from the selected inputs.

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  • Regueiro-Picallo, Manuel
    et al.
    Universidade da Coruña, Water and Environmental Engineering Group (GEAMA), Centro de Innovación Tecnolóxica en Edificación e Enxeñaría Civil (CITEEC), 15071 A Coruña, Spain.
    Langeveld, Jeroen
    Faculty of Civil Engineering and Geosciences, TU Delft, 2628 CN Delft, The Netherlands.
    Wei, Haoyu
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Bertrand-Krajewski, Jean-Luc
    University of Lyon, INSA Lyon, DEEP EA 7429, F-69621 Villeurbanne cedex, France.
    Rieckermann, Jörg
    Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland.
    Combining a daily temperature pattern analysis and a heat-pulse system to estimate sediment depths in sewer systems2024In: Environmental Science: Water Research & Technology, ISSN 2053-1400, E-ISSN 2053-1419Article in journal (Refereed)
    Abstract [en]

    Sediments in urban drainage systems (UDS) significantly impact their operation, so effective strategies are required to reduce their negative effects. Monitoring sediment accumulation provides valuable insights into sediment characteristics, sediment transport dynamics, and system performance. However, the effectiveness of monitoring systems is limited due to cost constraints and installation challenges. This study describes the development and application of a new system based on temperature dynamics to measure sediment depths in sewer systems. The methodology involves the analysis of temperature time series under dry weather flow conditions to identify harmonic patterns between wastewater and sediment-bed temperatures. These patterns are increasingly attenuated by increasing sediment depth. This study combines a system called MONitoring Temperatures in SEdiments (MONTSE), which integrates a dual-probe heat-pulse (DPHP) method to characterize sediment thermal properties, and a surrogate model, which includes temperature pattern analysis, to estimate sediment depths. Likewise, laboratory-scale experiments were performed to validate the temperature monitoring system and the surrogate model performance. The maximum absolute errors in measured sediment depths were less than 22 mm, and the uncertainty of the system was estimated at ±7.3 mm. Groundbreaking measurements of thermal properties of UDS sediments were also reported. Reliable information on sediment depths and properties was provided, so the system could significantly optimize sewer system operation and cleaning strategies.

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  • Nilsson, Kristina L.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Kostenius, Catrine
    Luleå University of Technology, Department of Health Sciences, Health and Rehabilitation.
    Berglund, Lotta
    Luleå University of Technology, Department of Health Sciences, Health and Rehabilitation.
    Tossavainen, Mia
    Luleå University of Technology, Department of Health Sciences, Health and Rehabilitation.
    Rautio, Arja (Contributor)
    Health Science. Arctic climate, Thule institut, Oulu University, Finland.
    Korpelainen, Raija (Contributor)
    Health science, physical activity, Oulu Deaconess Institute, Oulu University, Finland; Department of Sports and Exercise Medicine and Institute of Health Sciences, Oulu University, Finland.
    Tourula, Marjo (Contributor)
    Health science, Thule institute, Oulu University, Finland.
    Ikäheimo, Tiina (Contributor)
    Health science, Center for Environmental and Respiratory Health (CERH) and the Institute of Health Sciences, Oulu University, Finland.
    Rönkkö, Emilia (Contributor)
    Architecture, Oulu University, Finland.
    Rankka, Jenny (Contributor)
    Architecture, Oulu University, Finland.
    Espnes, Geir Arild (Contributor)
    Department of Social Work and Health Science, Norwegian University of Science and Technology, Norway.
    Kittang, Dag (Contributor)
    Architecture and planning, Norwegian University of Science and Technology, Norway.
    Maass, Ruca (Contributor)
    Department of Social Work and Health Science, Norwegian University of Science and Technology, Norway.
    Støa, Eli (Contributor)
    Department of Architectural Design and Management, Norwegian University of Science and Technology, Norway.
    Lepikkö, Tapio (Contributor)
    Metsähallitus, Oulu, Finland.
    Health on thin ice - urban planning for good health in cold climate2014Report (Other academic)
    Abstract [en]

    The purpose of the project was to develop a basis for a joint project application regarding urban planning and health promotion in cold climate with the co-partners at OU and if possible with a partner in Northern Norway. The aim was to establish a research platform and cooperation regarding at least one joint research and development application.Two workshops, one at Oulu University and one at Luleå university of technology, have been organized on the theme “urban planning for good health in cold climate”.In Oulu, the research and planning activities regarding the new suburb Hiukkavaara was the major focus on the workshop. In Luleå the resources and challenges with the cold climate and present winter conditions were the topic. Municipalities (Oulu, Pajala and Luleå), the county administrative board the county council of Norrbotten as well as companies were invited to the workshops. Several meetings with the project partners - both video and IRL (in real life) have been organized with researchers at OU and with NTNU, Trondheim. The planned work regarding investigation of cooperation with Tromsö or Finnmark University showed that our research activities and plans did not fit with any research groups at these places. However there was interest for the project both at UiT and at Asplan Viak (a consulting company).A physical research meeting at Ltu in February with researchers from NTNU, OU, Metsähallitus and Ltu resulted in a joint work with a general application that may be adjusted to calls from NordForsk, Horizon 2020, Interreg Nord and Kolarctic ENPI.All planned activities in the project have been performed and the partnership with OU is deepened and a partnership with NTNU is established. The partnership and coming research cooperation will be confirmed with one or several applications for funding projects regarding urban planning for built environment promoting health and wellbeing in cold climate. 

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  • Kumar, S.
    et al.
    Indian Inst Technol, Dept Mech & Ind Engn, Roorkee 247667, Uttarakhand, India.
    Cervantes, Michel J.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Gandhi, B.K.
    Indian Inst Technol, Dept Mech & Ind Engn, Roorkee 247667, Uttarakhand, India.
    Flow Field Analysis of Francis Turbine Draft Tube using POD at Design and Part Load Operating Conditions2024In: Journal of Applied Fluid Mechanics, ISSN 1735-3572, E-ISSN 1735-3645, Vol. 17, no 4, p. 770-784Article in journal (Refereed)
    Abstract [en]

    The hydraulic turbines, especially Francis turbines, frequently run at part load (PL) conditions to meet the dynamic energy needs. The flow field at the runner exit changes significantly with a change in the operating point. At PL, flow instabilities such as the Rotating Vortex Rope (RVR) form in the draft tube of the Francis turbine. The present paper compares the features of the velocity and vorticity field of the Francis turbine draft tube at the best efficiency point (BEP) and PL operations using the Proper Orthogonal Decomposition (POD) of the 2D-PIV data. The POD analysis decomposes the flow field into coherent and incoherent structures describing the spatiotemporal behavior of the flow field. A visual representation of the coherent structures and the turbulent length scales in the flow field is extracted and analyzed for BEP and PL, respectively. The study highlights the salient features of the draft tube flow field, which differentiate the BEP and PL operation. The fast Fourier transform of the temporal coefficients confirms the presence of RVR frequency (0.29 times the runner frequency) at PL. The phase portraits of different modes elucidate the relationship between different harmonics of the RVR frequency at PL.

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  • Rached Rydberg, Hanna
    Luleå University of Technology, Department of Health, Education and Technology.
    Hur kan lärarrollen förstås och anpassas i relation till samskapande undervisning?: Genom studenternas perspektiv Utvecklingsarbete2024Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When I found out that in 2022 there were about 18 000 students who did not have the qualifications to applay to high school after they finished ninth grade, I became curious about how I, in my future profession as a teacher, will be able to help students achieve passing grades in my subject social studies at the end of ninth grade.

    I have therefore studied what is required of the school´s curriculum Lgr 22 and how I can motivate the students as well as which working methods are presented in theory and previous research as the best working methods to enable the students to reach the right understanding of different subjects.

    It has been shown that co-creative teaching has been shown to provide a good basis for enabling this through, for example group work, which gave me the ideafor this study´s design.

    This development work is based on co-creative teaching in the form of a group project, where the students have answered a questionnaire and described how they experienced the teacher´s work before the task and how the teacher had structured everything around the task.

    The questions to the students have also touched on the subject of how the students experience group work and co-creative working methods and how they prefer to present their assignments in the future.

    The results of the study showed that the students need a lot of support and close cooperation with the teacher. They find it difficult to cooperate and, as research shows, it is difficult to find good group compositions.

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  • Wickström, Emelie
    Luleå University of Technology, Department of Health, Education and Technology.
    En aktiv reception: strategianvändning för att underlätta läsförståelsen i ett främmande språk2024Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien var att belysa en lässtrategis relevans för läsförståelsen i ett främmande språk för en grupp elever i kursen Moderna språk 3 på gymnasiet, genom tre läsförståelsetester. Vid testen fick eleverna samma text att läsa, och fick besvara samma innehållsfrågor. Halva gruppen arbetade enskilt men i övrigt på valfritt sätt, medan andra halvan fick arbeta med en förutbestämd strategi innehållande en gemensam aspekt. Studien grundar sig i en sociokulturell teori, där tanken är att det gemensamma arbetet i grupp B ska stärka elevernas enskilda resultat. I slutändan har kunnat konstateras att grupp B presterade bättre på två av tre test, och att grupp A konsekvent gör fler misstolkningar av textinnehållet. Alla elever har fått reflektera över sin strategianvändning vad gäller läsförståelse och eleverna i grupp B har även fått ta ställning kring vad de tyckte om den utvalda strategin, där en övervägande del var positivt inställd. Sammanfattningsvis kan resultaten användas för att som lärare kunna erbjuda eleverna olika strategier för läsförståelse som de kan använda sig av, för att finna de strategier som passar dem bäst. 

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  • Webiörn, Amelie
    Luleå University of Technology, Department of Health, Education and Technology.
    Samarbetets påverkan vid arbete med problemlösningsuppgifter i högstadiet: En studie av hur det kan påverka elever som uppvisat svårigheter att nå godkänt betyg i matematikämnet att få samarbeta med problemlösningsuppgifter2024Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta utvecklingsarbete har haft som syfte att undersöka hur det påverkar högstadieelever som uppvisat svårigheter att nå upp till godkänt betyg i matematikämnet att få samarbeta när de ska försöka lösa problemlösningsuppgifter inom matematik. En grupp bestående av 15 elever i åk 7 på en skola har fått försöka lösa tre uppgifter enskilt och en uppgift i par samt svarat på en utvärdering och sedan har elevlösningarna och svaren på utvärderingen analyserats.

    Resultatet av dessa analyser har visat att eleverna i högre grad fått bättre resultat på uppgiften de fick försöka lösa i par än uppgifterna de fick försöka lösa enskilt, att eleverna för det mesta visat fler av de matematiska förmågorna när de fått samarbeta än när de jobbat enskilt samt att de flesta elever upplevde att det gick bättre när de fick samarbeta. Det visar även att det verkar ha haft en något positiv påverkan när eleverna först hade fått samarbeta på en uppgift och sedan fick försöka lösa en liknande uppgift enskilt.

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  • Isaksson, William
    Luleå University of Technology, Department of Health, Education and Technology.
    Boogie-woogie-skolan: Pianoelevens väg till lustfylld improvisation2024Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Med anledningen av att jag upptäckt en stor rädsla för improvisation bland elever har syftet med utvecklingsarbetet varit att undersöka hur en lektionsserie i musikstilen boogie-woogie inverkar på pianoelevers relation till improvisation. Undersökningen har genomförts på individuella pianolektioner, på en gymnasieskola, där lektionerna bestått av specifika metodiska tillvägagångsätt för improvisation inom ramen för den givna musikstilen. Innan lektionsseriens start och efter lektionsseriens avslut har eleverna intervjuats i syfte att kunna besvara studiens frågeställningar huruvida elevernas relation till improvisation förändrats. Under den inledande intervjun framkom det att fyra av fem informanter hade väldigt liten erfarenhet av improvisation. Genom undervisning om konkreta improvisationsmetoder i en musikstil som förespråkar lekfullhet har informanternas relation till improvisation stärkts. Informanterna med liten tidigare erfarenheter har uttryckt att de vågar improvisera i högre utsträckning, medan informanten med stor tidigare erfarenhet anser sig ha fått fördjupad förståelse för olika improvisationsmetoder. Samtliga elevers självförtroende som pianister har även stärkts till följd av genrespecifika inslag. Undersökningen visar att begränsningar i musicerandet gör improviserandet mer lustfyllt och avspänt. 

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  • Saeed, Mohazzam
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Otsuki, Akira
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hermes, Michiel
    SUPA and School of Physics and Astronomy, The University of Edinburgh,Edinburgh, UK.
    ul Hassan, Ali Zain
    School of Electrical Engineering and Computer Science, National University of Science and Technology, Islamabad,Pakistan.
    Aziz, Abdullah
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Tracking colloidal silica particles to evaluate their dispersion and interactions in concentrated suspensions under shear force applications2024In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683Article in journal (Refereed)
    Abstract [en]

    This study aimed to characterize interactions within colloidal silica particles in their concentrated suspensions, using rheo-confocal measurements and imaging, followed by image analysis. We studied the effect of shear rate (0-500 s-1) and solution pH (6, 10) on the dispersion degree of colloidal silica particles via the determination and comparison of interparticle distances and their modeling. Images corresponding to different shear rates were analyzed to identify the coordinates of the particles. These coordinates were further analyzed to calculate the distance among the particles and then their surface-to-surface distance normalized by the particle diameter (H/D). It was found that the population of the particles per unit area of the image and H/D varied with increasing shear rate. The comparison between experimentally measured and theoretically calculated H/D identified that for some particles, the former was shorter than the latter, indicating the unexpected attractions among them against the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Then, the modification of previously reported equations for H/D was suggested and confirmed its validity. Assuming pair potential interaction and hydrodynamic interaction were the main non-DLVO interactions, their magnitudes were calculated and confirmed the significance of pH and shear application strength on particle dispersion/coagulation.

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  • Olsson Sjögren, Carl-Otto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    CFD-simulering av värmeöverföring under upptändningsförlopp av krutraketmotor2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    SAAB Dynamics produces and develops several products that use solid-propellant rocket engines. The performance of these rocket engines is heavily dependant upon an efficient ignition. It is desirable to be able to predict this sequence numerically with good accuracy. No established simulation methodology exists as of today however. This master thesis is a first step towards the investigation of how the initial ignition sequence can be modelled using Computational Fluid Dynamics. The commercial software Ansys Fluent has been used as a tool for simulation. The initial heat transfer during ignition is a transient sequence and involves several complex heat transfer mechanisms. Some of the most important ones include convective heat transfer from ignition gases, conduction from ignition particles as well as thermal radiation from both the gases and particles. Three models are presented. They model an approximate geometry from earlier experimental investigations and simulate 2.4 milliseconds of the initial ignition sequence. No chemical reactions are modelled. Model 1 simulates convective heat transfer from hot ignition gases. Model 2 includes thermal radiation from the ignition gases that is modelled using Planck-mean absorption coefficients and the Discrete Ordinates model. Total heat transfer rates and final temperature distributions along the surface of the propellant are reported. The models predict similar total heat transfer rates and final temperature distributions, with somewhat elevated levels for model 2. An experimentally measured pressure is used to validate the simulated pressure levels. Physical validity is also evaluated by comparing the temperature of the ignition gas to the adiabatic flame temperature. Both models perform satisfactorily with regards to these metrics. A third model that attempts to model the ignition particles using the Discrete Phase Model is also presented. The model is deemed unreliable due to numerical problems for the simulated case. Finally sources of error and possible future work is discussed.

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  • Alharmoodi, Ahmed Abdulla
    et al.
    College of Business, Abu Dhabi University, Abu Dhabi, United Arab Emirates.
    Khan, Mehmood
    College of Business, University of Sharjah, Sharjah, United Arab Emirates.
    Mertzanis, Charilaos
    College of Business, Abu Dhabi University, Abu Dhabi, United Arab Emirates.
    Gupta, Shivam
    Department of Information Systems, Supply Chain Management & Decision Support, NEOMA Business School, Reims, France.
    Mikalef, Patrick
    Department of Computer Science, Faculty of Information Technology and Electrical Engineering, Norwegian University of Science and Technology, Norway; Department of Technology Management, SINTEF Digital, Trondheim, Norway; School of Economics and Business, University of Ljubljana, Ljubljana, Slovenia.
    Parida, Vinit
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Business Administration and Industrial Engineering. Department of Management, University of Vaasa, Vaasa, Finland.
    Co-creation and critical factors for the development of an efficient public e-tourism system2024In: Journal of Business Research, ISSN 0148-2963, E-ISSN 1873-7978, Vol. 174, article id 114519Article in journal (Refereed)
    Abstract [en]

    This study identifies the factors that guide the adoption of a public e-tourism system resulting in value co-creation in the UAE. Integrating and comparing factors drawn from the third version of the Technology Acceptance Model (TAM3), the Technology-Task-Fit (TTF) theory, and push-to-use, an Analytic Hierarch Process (AHP) model was implemented with data collected using a structured questionnaire from purposively selected UAE e-tourism experts (N = 15) and analyzed using Microsoft Excel. The findings revealed that usefulness, convenience of use, and push-to-use were the most critical aspects for achieving an efficient public e-tourism system that allows for value co-creation in that order of ranking. The findings also suggest that computer self-efficiency is the most critical factor in effectively establishing an e-tourism system followed by government push-to-use. In conclusion, the findings demonstrate that usefulness and ease-of-use backed by computer self-efficiency, result demonstrability, and output quality are vital for the efficient adoption of a public e-tourism system resulting in value co-creation in the UAE.

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  • Müller, Michael
    et al.
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany; Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Enghardt, Stefan
    Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Kuczyk, Martin
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany; Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Riede, Mirko
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany.
    López, Elena
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany.
    Brueckner, Frank
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany.
    Marquardt, Axel
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany; Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Leyens, Christoph
    Department of Additive Manufacturing and Printing, Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany; Institute of Materials Science, Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 7, 01069 Dresden, Germany.
    Microstructure of NiAl-Ta-Cr in situ alloyed by induction-assisted laser-based directed energy deposition2024In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 238, article id 112667Article in journal (Refereed)
    Abstract [en]

    The development of new high temperature materials for coatings as well as structural components is an important topic to contribute to a higher efficiency and sustainability of e.g. gas turbine engines. One promising new class of high temperature materials are NiAl-based alloys. Within this study, the microstructure and microhardness of NiAl-Ta-Cr alloys with varying Cr and Ta content were investigated. Graded specimens were fabricated by laser-based directed energy deposition utilizing an in situ alloying approach by mixing elemental Ta and Cr as well as pre-alloyed NiAl powder. Thermodynamic calculations were performed to design the alloy compositions beforehand. Inductive preheating of the substrate was used to counter the challenge of cracking due to the high brittleness. The results show that the cracking decreases with increasing preheating temperature. However, even at 700 °C, the cracking cannot be fully eliminated. Scanning electron microscopy, X-ray diffraction and electron backscatter diffraction revealed the formation of the phases B2-NiAl, A2-Cr and C14-NiAlTa within NiAl-Ta and NiAl-Cr alloys. For NiAl-Ta-Cr compositions, deviations regarding the phase formation between calculation and experiment were observed. Maximum hardness values were achieved within the NiAl-Ta and NiAl-Ta-Cr systems for the eutectic compositions at 14 at.-% Ta with maximum values above 900 HV0.1.

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  • Barbera, Mariagnese
    et al.
    Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, Yliopistonranta 1C, 70211, Kuopio, Finland; The Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, Charing Cross Hospital, St Dunstan’s Road, LondonLondon, W6 8RP, UK.
    Lehtisalo, Jenni
    Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, Yliopistonranta 1C, 70211, Kuopio, Finland; Population Health Unit, Finnish Institute for Health and Welfare, Mannerheimintie 166, P.O. Box 30, Helsinki, Finland.
    Perera, Dinithi
    The Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, Charing Cross Hospital, St Dunstan’s Road, London, W6 8RP, UK; FINGERS Brain Health Institute, C/O Stockholms Sjukhem, Box 122 30, SE-102 26, Stockholm, Sweden.
    Aspö, Malin
    Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Karolinska Vägen 37A, 171 64, Solna, Sweden; Theme Inflammation and Aging, Medical Unit Aging, Karolinska University Hospital, Karolinska Vägen 37A, 171 76, Solna, Sweden.
    Cross, Mary
    Imperial Clinical Trials Unit, School of Public Health, Faculty of Medicine, Imperial College London, Imperial College London, Stadium House, 68 Wood Lane, London, W12 7RH, UK.
    De Jager Loots, Celeste A.
    The Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, Charing Cross Hospital, St Dunstan’s Road, LondonLondon, W6 8RP, UK.
    Falaschetti, Emanuela
    Imperial Clinical Trials Unit, School of Public Health, Faculty of Medicine, Imperial College London, Imperial College London, Stadium House, 68 Wood Lane, London, W12 7RH, UK.
    Friel, Naomi
    The Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, Charing Cross Hospital, St Dunstan’s Road, LondonLondon, W6 8RP, UK.
    Luchsinger, José A.
    Departments of Medicine and Epidemiology, Columbia University Irving Medical Center, 622 W 168Th St, New York, NY, USA.
    Gavelin, Hanna Malmberg
    Department of Psychology, Umeå University, 901 87, Umeå, Sweden.
    Peltonen, Markku
    Population Health Unit, Finnish Institute for Health and Welfare, Mannerheimintie 166, P.O. Box 30, Helsinki, Finland; FINGERS Brain Health Institute, C/O Stockholms Sjukhem, Box 122 30, SE-102 26, Stockholm, Sweden.
    Price, Geraint
    The Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, Charing Cross Hospital, St Dunstan’s Road, LondonLondon, W6 8RP, UK.
    Stigsdotter Neely, Anna
    Luleå University of Technology, Department of Health, Education and Technology, Health, Medicine and Rehabilitation. Department of Social and Psychological Studies, Karlstad University, 651 88, Karlstad, Sweden.
    Thunborg, Charlotta
    Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Karolinska Vägen 37A, 171 64, Solna, Sweden; Theme Inflammation and Aging, Medical Unit Aging, Karolinska University Hospital, Karolinska Vägen 37A, 171 76, Solna, Sweden.
    Tuomilehto, Jaakko
    Population Health Unit, Finnish Institute for Health and Welfare, Mannerheimintie 166, P.O. Box 30, Helsinki, Finland; Department of Public Health, University of Helsinki, PO BOX 20, 00014, Helsinki, Finland; Diabetes Research Group, King Abdulaziz University, 21589, Jeddah, Saudi Arabia.
    Mangialasche, Francesca
    FINGERS Brain Health Institute, C/O Stockholms Sjukhem, Box 122 30, SE-102 26, Stockholm, Sweden; Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Karolinska Vägen 37A, 171 64, Solna, Sweden; Theme Inflammation and Aging, Medical Unit Aging, Karolinska University Hospital, Karolinska Vägen 37A, 171 76, Solna, Sweden.
    Middleton, Lefkos
    The Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, Charing Cross Hospital, St Dunstan’s Road, LondonLondon, W6 8RP, UK; Directorate of Public Health, Imperial College NHS Healthcare Trust Hospitals, Praed Street, London, W2 1NY, UK.
    Ngandu, Tiia
    Population Health Unit, Finnish Institute for Health and Welfare, Mannerheimintie 166, P.O. Box 30, Helsinki, Finland; Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Karolinska Vägen 37A, 171 64, Solna, Sweden.
    Solomon, Alina
    Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, Yliopistonranta 1C, 70211, Kuopio, Finland; The Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, Charing Cross Hospital, St Dunstan’s Road, London, W6 8RP, UK; Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Karolinska Vägen 37A, 171 64, Solna, Sweden.
    Kivipelto, Miia
    The Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, Charing Cross Hospital, St Dunstan’s Road, LondonLondon, W6 8RP, UK; Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Karolinska Vägen 37A, 171 64, Solna, Sweden; Theme Inflammation and Aging, Medical Unit Aging, Karolinska University Hospital, Karolinska Vägen 37A, 171 76, Solna, Sweden; Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Yliopistonranta 1C, 70211, Kuopio, Finland.
    A multimodal precision-prevention approach combining lifestyle intervention with metformin repurposing to prevent cognitive impairment and disability: the MET-FINGER randomised controlled trial protocol2024In: Alzheimer's Research & Therapy, E-ISSN 1758-9193, Vol. 16, no 1, article id 23Article in journal (Refereed)
    Abstract [en]

    Background: Combining multimodal lifestyle interventions and disease-modifying drugs (novel or repurposed) could provide novel precision approaches to prevent cognitive impairment. Metformin is a promising candidate in view of the well-established link between type 2 diabetes (T2D) and Alzheimer’s Disease and emerging evidence of its potential neuro-protective effects (e.g. vascular, metabolic, anti-senescence). MET-FINGER aims to test a FINGER 2.0 multimodal intervention, combining an updated FINGER multidomain lifestyle intervention with metformin, where appropriate, in an APOE ε4-enriched population of older adults (60–79 years) at increased risk of dementia. Methods: MET-FINGER is an international randomised, controlled, parallel-group, phase-IIb proof-of-concept clinical trial, where metformin is included through a trial-within-trial design. 600 participants will be recruited at three sites (UK, Finland, Sweden). Participants at increased risk of dementia based on vascular risk factors and cognitive screening, will be first randomised to the FINGER 2.0 intervention (lifestyle + metformin if eligible; active arm) or to receive regular health advice (control arm). Participants allocated to the FINGER 2.0 intervention group at risk indicators of T2D will be additionally randomised to receive metformin (2000 mg/day or 1000 mg/day) or placebo. The study duration is 2 years. The changes in global cognition (primary outcome, using a Neuropsychological Test Battery), memory, executive function, and processing speed cognitive domains; functional status; lifestyle, vascular, metabolic, and other dementia-related risk factors (secondary outcomes), will be compared between the FINGER 2.0 intervention and the control arm. The feasibility, potential interaction (between-groups differences in healthy lifestyle changes), and disease-modifying effects of the lifestyle-metformin combination will be exploratory outcomes. The lifestyle intervention is adapted from the original FINGER trial (diet, physical activity, cognitive training, monitoring of cardiovascular/metabolic risk factors, social interaction) to be consistently delivered in three countries. Metformin is administered as Glucophage®XR/SR 500, (500 mg oral tablets). The metformin/placebo treatment will be double blinded. Conclusion: MET-FINGER is the first trial combining a multimodal lifestyle intervention with a putative repurposed disease-modifying drug for cognitive impairment prevention. Although preliminary, its findings will provide crucial information for innovative precision prevention strategies and form the basis for a larger phase-III trial design and future research in this field. Trial registration: ClinicalTrials.gov (NCT05109169).

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  • Rattan, Avantika
    et al.
    School of Mechanical Engineering (SMEC), Vellore Institute of Technology, Chennai, India.
    Venkatesh S, Naveen
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. School of Mechanical Engineering (SMEC), Vellore Institute of Technology, Chennai, India.
    Sugumaran, V.
    School of Mechanical Engineering (SMEC), Vellore Institute of Technology, Chennai, India.
    Anoop, P. S.
    School of Mechanical Engineering (SMEC), Vellore Institute of Technology, Chennai, India; Sustainable Mobility Automobile Research Technology (SMART) Center, Dept. of Electronics and Communication Engineering, AmritaVishwa Vidyapeetham, Amritapuri, India.
    Monitoring the condition of nitrogen-filled tires using weightless neural networks2024In: Automatika: Journal for Control, Measurement, Electronics, Computing and Communications, ISSN 0005-1144, E-ISSN 1848-3380, Vol. 65, no 2, p. 523-537Article in journal (Refereed)
    Abstract [en]

    The novelty of this paper revolves around monitoring the condition of nitrogen-filled tiresthrough the fusion of features and utilization of weightless neural networks. A tire pressuremonitoring system (TPMS) plays a crucial role in ensuring vehicle safety and comfort. Recklessdriving, poor road conditions, continual operation, higher road friction and excessive load arecertain factors that can degrade the longevity of tires. Such conditions can result in instanta-neous fault attacks in tires raising a concern for safety and comfort. To apply instantaneous andaccurate fault diagnosis, the present study leverages machine learning techniques through theintegration of an adaptive and robust algorithm, namely, the Wilkes, Stonham and AleksanderRecognition Device (WiSARD) classifier. The experiment uses three types of features namely, sta-tistical, histogram and autoregressive moving average (ARMA) features. The J48 decision treealgorithm was used to pinpoint the key attributes crucial for classification. Following this, theidentified attributes were segregated into training and testing datasets, facilitating the evalua-tion of the WiSARD classifier. Hyperparameter tuning was carried out to achieve optimal valuefor maximizing classification accuracy and minimizing computational time. Among the featuresconsidered, ARMA features delivered the best test set accuracy of about 96.18%.

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  • Svensson, Ludvig
    Luleå University of Technology, Department of Social Sciences, Technology and Arts.
    Måluppfyllelse och meningsskapande: En kvalitativ studie av medarbetares meningsskapande för hållbar utveckling2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to investigate sensemaking among employees within large service companies regarding sustainable development. To fulfill the purpose and address the research questions, the study has been conducted through six semi-structured interviews with employees from three major service companies. The collected data has been coded and thematically analyzed using a thematic analysis method, guided by the theoretical framework consisting of new institutional theory (DiMaggio & Powell, 1983; Meyer & Rowan, 1977) and Karl Weick's (1995) sensemaking.

    The findings of the study indicate that the sensemaking process is a significant element in the interviewees' daily work towards achieving sustainability goals. Through an ongoing process of interpretation, employees create meaning for why and how they should work towards sustainable development.

    Furthermore, the results reveal that the primary motive behind organizing for sustainable development is a pursuit of a leading position within the organizational field and credibility within the institutional environment. The organizations and employees align with societal developments and attempt to adapt to prevailing institutional requirements and norms, which strongly influence their sensemaking. Societal developments and the institutional environment also have a strong impact on which dimension of sustainability is most prominent and dominant.

    In conclusion, the results demonstrate that employees' sensemaking plays a central role in the organizations' organizing for sustainable development. The sensemaking process is not an independent factor that solely contributes to organizing, but it is greatly influenced by the institutional environment surrounding the organizational field.

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  • Maghami, Sara
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johansson, Örjan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Structural acoustic design of a sonicator to enhance energy transfer efficiency2024In: Ultrasonics sonochemistry, ISSN 1350-4177, E-ISSN 1873-2828, article id 106804Article in journal (Refereed)
    Abstract [en]

    The study focuses on developing a comprehensive design approach for a flow-through ultrasonic reactor (sonicator) to tackle challenges like low energy transfer efficiency and unstable system performance. The simulation accounts for structural vibrations, structural-fluid interactions, and pressure distributions within the cavitation zone under single-frequency excitation. Different geometrical designs of cylindrical sonicators are analyzed, with input parameters tailored to acquire higher acoustic cavitation intensity. The findings reveal a novel hexagonal ring-shaped excitation structure that reduces coupling losses, ensures uniform acoustic pressure distribution, and generates symmetric vibration mode shapes. The study emphasizes the separation of parasitic modes from the desired resonance frequency response and simulates the influence of bubbly liquid properties through complex wave numbers and harmonic responses. Experimental validation on a manufactured prototype, including mechanical and electrical impedance, sound pressure spectrum, and cavitation intensity, supports the simulated results. Ultimately, the sonicator exhibits three feasible resonance frequencies to be used pairwise at the certain temperature and input power interval for different applications.

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  • Hilmersson, Erik
    Luleå University of Technology, Department of Social Sciences, Technology and Arts.
    Statistisk processtyrning: Multivariat analys med PCA för detektering av processavvikelser på Billerud Karlsborg2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
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  • Shen, Chunguang
    et al.
    State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang, 110819, Liaoning, China; Department of Materials Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44, Stockholm, Sweden; Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology, School of Materials Science and Engineering, Hebei University of Technology, Tianjin, 300401, China.
    Mu, Wangzhong
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Materials Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44, Stockholm, Sweden.
    Wang, Chenchong
    State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang, 110819, Liaoning, China.
    Xu, Wei
    State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang, 110819, Liaoning, China.
    Hedström, Peter
    Department of Materials Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 100 44, Stockholm, Sweden; Ferritico, Valhallavägen 79, 114 28, Stockholm, Sweden.
    Uncovering the generic and alloy-specific governing parameters of deformation-induced martensitic transformation in austenitic steel2024In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803Article in journal (Refereed)
    Abstract [en]

    In this work, a hybrid modeling approach, combining machine learning (ML)and computational thermodynamics, has been applied to predict deformationinduced martensitic transformation (DIMT) and explore the generic and alloyspecifc parameters governing DIMT in austenitic steels. The DIMT model wasestablished based on the ensemble ML algorithms and a comprehensive set ofphysical variables. The developed model is highly generalizable as validated onunseen alloys. The generic governing parameters of DIMT are in good agreementwith previous studies in the literature. However, the evaluated alloy-specifcgoverning parameters reveal large diferences between grades, e.g., 204 series ofaustenitic stainless steels has a quite balanced correlation between strain, stress,temperature, and DIMT, while the 301 series has much stronger correlationbetween stress and DIMT. The fndings in the current study emphasize theimportance that a general DIMT model for steels should include both stress andstrain, as well as other governing parameters, since DIMT can be both stressassisted and strain-induced transformation, and often the effect of appliedmechanical driving force and the formation of new nucleation sites interact.

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  • Gunem, Nabil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Byggplatsuppföljning inom vägprojekt: En fallstudie om samverkan och erfarenhetsåterföring2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Byggplatsuppföljning är ett omfattande arbete bestående av flera arbetsmoment, såsom uppföljning av entreprenadkontraktet och tillhörande bygghandlingar under produktionsskedet och vidare till överlämnande av projekt för förvaltning. Därmed är byggplatsuppföljningen ett väsentligt arbete och kräver kompetens i diverse teknikområden såsom väg, el och brokonstruktioner med flera. I en entreprenad anses byggplatsuppföljningen vara som klar förutsättning för att klara uppdragen på grund av ökad komplexitet och krav som ska följas.

    Denna funktion har inte använts så länge och anses fortfarande vara ett ganska nytt koncept och outforskat område.

    Denna artikel omfattar en multipel fallstudie som undersöker tre olika utförandeentreprenader i olika storlekar.

    Syftet med denna studie är att undersöka byggplatsuppföljarens roll inom valda uppdrag genom att studera hur denna roll påverkar samverkan och erfarenhetsåterföring mellan beställare, entreprenör och konsult i projekten.

    För att genomföra denna studie har en kvalitativ metod använts bestående en kombination av intervjustudie samt dokumentstudie.

    Resultatet belyser hur byggplatsuppföljnings organisationen påverkar samarbetet i dessa uppdrag, vilka aktiviteter som gynnar/missgynnar samverkan, hur parterna arbetar med erfarenhetsåterföring och vilka utmaningar det finns med erfarenhetsåterföring.

    Resultatet diskuterar även samverkan ur tre olika perspektiv kopplat till beställare, entreprenör och konsult och hur dessa aktörer ser på samarbetet och vilka utmaningar de upplever kopplat till samverkan och erfarenhetsåterföring.

    I studien framkom även att de undersökta uppdragen präglades av bristfällig samverkan i samband med bemanning av projekt med stora organisationer.

    Gällande erfarenhetsåterföring finns det även brister kopplat till arbetsprocessen för gemensamt arbete med erfarenhetsåterföring. Studien påvisar även att erfarenheterna från produktionsskedet inte når till projekterande konsulter även i paketerade uppdrag.

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  • Bahaloohoreh, Hassan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Forsberg, Fredrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lycksam, Henrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Casselgren, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Material mapping strategy to identify the density-dependent properties of dry natural snow2024In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 130, no 2, article id 141Article in journal (Refereed)
    Abstract [en]

    The mechanical properties of natural snow play a crucial role in understanding glaciers, avalanches, polar regions, and snow-related constructions. Research has concentrated on how the mechanical properties of snow vary, primarily with its density; the integration of cutting-edge techniques like micro-tomography with traditional loading methods can enhance our comprehension of these properties in natural snow. This study employs CT imaging and uniaxial compression tests, along with the Digital Volume Correlation (DVC) to investigate the density-dependent material properties of natural snow. The data from two snow samples, one initially non-compressed (test 1) and the other initially compressed (test 2), were fed into Burger’s viscoelastic model to estimate the material properties. CT imaging with 801 projections captures the three-dimensional structure of the snow initially and after each loading step at -18C, using a constant deformation rate (0.2 mm/min). The relative density of the snow, ranging from 0.175 to 0.39 (equivalent to 160–360 kg/m), is determined at each load step through binary image segmentation. Modulus and viscosity terms, estimated from Burger’s model, exhibit a density-dependent increase. Maxwell and Kelvin–Voigt moduli range from 0.5 to 14 MPa and 0.1 to 0.8 MPa, respectively. Viscosity values for the Maxwell and Kelvin–Voigt models vary from 0.2 to 2.9 GPa-s and 0.2 to 2.3 GPa-s within the considered density range, showing an exponent between 3 and 4 when represented as power functions. Initial grain characteristics for tests 1 and 2, obtained through image segmentation, reveal an average Specific Surface Area (SSA) of around 55 1/mm and 40 1/mm, respectively. The full-field strain distribution in the specimen at each load step is calculated using the DVC, highlighting strong strain localization indicative of non-homogeneous behavior in natural snow. These findings not only contribute to our understanding of natural snow mechanics but also hold implications for applications in fields such as glacier dynamics and avalanche prediction.

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  • Savolainen, Eva
    et al.
    Luleå University of Technology, Department of Health, Education and Technology, Health, Medicine and Rehabilitation.
    Lindqvist, Anna-Karin
    Luleå University of Technology, Department of Health, Education and Technology, Health, Medicine and Rehabilitation.
    Mikaelsson, Katarina
    Luleå University of Technology, Department of Health, Education and Technology, Health, Medicine and Rehabilitation.
    Nyberg, Lars
    Luleå University of Technology, Department of Health, Education and Technology, Health, Medicine and Rehabilitation.
    Rutberg, Stina
    Luleå University of Technology, Department of Health, Education and Technology, Health, Medicine and Rehabilitation.
    Children’s active school transportation: an international scoping review of psychosocial factors2024In: Systematic Reviews, ISSN 2046-4053, Vol. 13, no 1, article id 47Article in journal (Refereed)
    Abstract [en]

    Background: Over the last decades, the prevalence of AST has decreased significantly. Barriers to active school transport (AST) have been extensively examined in the literature, while psychosocial factors that facilitate AST have received less attention. To our best knowledge, there are currently no reviews on this subject. Therefore, the objective of this review was to scope the literature and identify published research about psychosocial factors related to AST.

    Methods: Systematic searches conducted in PubMed, Web of Science, TRID, Scopus, and ERIC resulted in a total of 1933 publications, and 77 of them were considered eligible for this review.

    Results: The results of the included articles were categorised into four psychosocial factors: confidence in ability, attitudes, social support, and social norms, which were all generally positively related to AST, with a few exceptions.

    Conclusion: The findings of this review indicate that these psychosocial factors may be important to consider when developing interventions and highlight that both children and parents should be involved in the process. This knowledge can serve as a valuable guide for developing interventions to promote AST. However, the evidence base supporting these psychosocial factors requires further investigation to fully understand how and when to incorporate them to maximise AST efficacy.

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  • Olsson, Amanda
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Adapted data collection in field utilizing RMR and the Q-system2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The focus on slope stability has increased rapidly in Norway over the last years due to several unwanted landslides. In Norway, the most used method today to classify the rock mass and to determine the required reinforcement, is the Q-system. In addition to that the RMR method is also a commonly used method. However, since both the RMR and the Q-system is created to be used for underground constructions, their slope adaptations (Q-slope and SMR) has been developed. These adaptations will also be evaluated in this thesis. They will be used to examine if there is a correlation between the classification systems and the installed support on site. This thesis will only focus on slopes and not tunnels, as a limit to the scope investigated.  The joints properties at the investigated sites are taken both from engineering geologist reports and field mapping. The mapped joints will be analyzed in Dips to determine the major joint sets and by using the kinematic analysis tool determine what failure mechanisms these joint sets may create. These joint sets will be further evaluated through numerical analysis (with e.g. RocPlane, Swedge or RocTopple) dependent on their failure mechanism. The rock and joint data for calculation is gathered from three different sites, which are all part of the same project where the traffic capacity of the European route E18 through Porsgrunn, outside of Oslo, is increased. In both Blåfjell and Bjønnås the rock mass is larvikite, but in Grenland the rock mass investigated is sandstone. However, the sandstone in the Grenland has undergone contact metamorphosis, which changes the characteristics of the rock mass and creating a much stronger sandstone.  Generally, the rock mass investigated is classified to be of similar quality which gives them the same strength. Consequently, it is difficult to determine any kind of correlation between the sites. The results do not indicate the expected relationship that a stronger rock mass would need less reinforcement. In addition, it is also observed that the classification systems generally recommend more shotcrete that what is installed on site. When comparing the different classification systems, it can be seen that the Q-system generally categorize the rock mass in a lower category, indicating a weaker rock mass, compared to RMR and SMR. This then results in that the rock masses investigated is classified to be ranging from Poor to Good, dependent on the classification method.  

    Keywords: Rock mass classification, Q-slope, SMR, Slope stability.  

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  • Åström, Johannes
    et al.
    Luleå University of Technology, Department of Social Sciences, Technology and Arts.
    Karlelid, Jakob
    Luleå University of Technology, Department of Social Sciences, Technology and Arts.
    Unraveling Paradoxical Tensions in Digital Servitization Ecosystems: A case study in the mining industry2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Purpose - This study aims to understand what paradoxical tensions arise within an ecosystem when companies collectively pursue digital servitization and how these tensions impact value co-creation.

    Method -  The study is an explorative single-case study based on the mining industry in Sweden and involves respondents from industry-leading organizations. A total of 30 interviews were conducted and analyzed through a thematic analysis.

    Findings – Our study has identified five paradoxical tensions that arise during the process of digital servitization in ecosystems. These tensions are the paradox of competition and cooperation, the tension between IP sharing and control preservation, the tension of skill transition and reluctance to change, the tension between traditional identity and digital identity, and the need to balance data access and data security. The findings also identified the impact that the tensions have on value co-creation.

    Theoretical contributions – Our study demonstrates the intricate nature of tensions within ecosystems, revealing their multifaceted origins stemming from factors such as ecosystem coopetition, organizational identity dynamics, and data utilization practices. Additionally, we highlight that these tensions can manifest at two levels: within organizations and between ecosystem partners. Our research provides a more nuanced understanding of the complex and multi-faceted nature of tensions in ecosystems.

    Managerial contributions – This study provides valuable insights for managers of the impact on value co-creation of paradoxical tensions within a digital servitization ecosystem. We highlight the significance of recognizing and addressing tensions in ecosystem collaborations. By unpacking the complexity of tensions, we contribute to mitigating conflicts and enhancing the effectiveness of business ecosystems in practical settings.

    Limitations – This research is based on a single case study in the mining industry. Therefore, there are opportunities for future research to investigate the applicability of the findings in other industrial contexts.

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  • Nordell, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Söderlund, Monika
    Solar Energy and Heat Storage1991 (ed. 3)Book (Other academic)
    Abstract [en]

    This book was originally published at Luleå University of Technology in 1987 fulfilling a need within Sweden to disseminate the techniques of alternative heating using solar energy in association with energy storage. In the year 2000 it was realised that the book required updating. This second edition contains a number of changes that bring it up to date, and at the same time, it was made accessible to a much wider audience by being translated into English. 

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  • La Hera, Pedro
    et al.
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences Umeå Campus Umeå Sweden.
    Mendoza-Trejo, Omar
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå Campus, Umeå, Sweden.
    Lindroos, Ola
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå Campus, Umeå, Sweden.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindbäck, Torbjörn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Latif, Saira
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Li, Songyu
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Exploring the feasibility of autonomous forestry operations: Results from the first experimental unmanned machine2024In: Journal of Field Robotics, ISSN 1556-4959, E-ISSN 1556-4967Article in journal (Refereed)
    Abstract [en]

    This article presents a study on the world's first unmanned machine designed for autonomous forestry operations. In response to the challenges associated with traditional forestry operations, we developed a platform equipped with essential hardware components necessary for performing autonomous forwarding tasks. Through the use of computer vision, autonomous navigation, and manipulator control algorithms, the machine is able to pick up logs from the ground and manoeuvre through a range of forest terrains without the need for human intervention. Our initial results demonstrate the potential for safe and efficient autonomous extraction of logs in the cut-to-length harvesting process. We achieved a high level of accuracy in our computer vision system, and our autonomous navigation system proved to be highly efficient. This research represents a significant milestone in the field of autonomous outdoor robotics, with far-reaching implications for the future of forestry operations. By reducing the need for human labor, autonomous machines have the potential to increase productivity and reduce labor costs, while also minimizing the environmental impact of timber harvesting. The success of our study highlights the potential for further development and optimization of autonomous machines in the forestry industry.

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  • Berggren, Holger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Ola, Bergstedt
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    FE-Modelling of Composite Girder tests2024Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Many of the existing steel-concrete bridges may need to be strengthened, as heavier vehicles areallowed on the Swedish roads. These bridges could possibly be strengthened by post-installingshear connectors. The shear connectors may enhance the load-bearing capacity through a higherdegree of composite action between the steel and concrete interface.For post-installing of shear connectors, it is advantageous to use a method that allows forinstallation from underneath the bridge as it avoids disrupting the traffic flow. The authors havehence focused on a shear connector called coiled spring pin (CSP); a sheet of metal rolled intoa coil. It’s inserted by hydraulic jacking into a pre-drilled hole and maintained in position dueto radial spring force, avoiding the need for welding.Information and data are collected from beam tests performed at Luleå technical university, theEurocodes and literature.This study investigates and identifies the behaviour and characteristics of a partial compositegirder reinforced with CSPs. The study compares the results obtained from the laboratory testsand the FEM-simulations. Furthermore, this research examines the factors that contribute to theaccuracy of the FEM models and investigates the influence of the CSP placement on the overallload-bearing capacity.Both the FEM simulations and laboratory tests indicate that the girders exhibit strength benefitsfrom applying CSPs. An optimal position for the connectors could not be determined, as theresults presented in the simulations was not proved by the laboratory tests. The simulationsindicate benefits with central placed CSPs, in contrast to the laboratory test where no differencesfrom the placement were shown, although only two test setups were used. 

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  • Osadcha, Natalia
    et al.
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Social Sciences.
    Zaverbnyj, Andrij
    Doctor of Economic Sciences, Professor, Lviv Polytechnic National University, Ukraine.
    Assessment of the Energy System of Ukraine: Ways of Recovery, Cases of Development2024In: European Journal of Sustainable Development, ISSN 2239-5938, E-ISSN 2239-6101, Vol. 13, no 1, article id 185Article in journal (Refereed)
    Abstract [en]

    The economy of Ukraine is partially destroyed and poses an energy threat to European countries. The article analyzes trends in the development of consumption in Ukraine, and assesses the prospects for development. Energy Ukraine's system depends on fossil fuels. The government sought to diversify risks and ensure sustainable development. The energy consumption market is characterized by a decline and an increase in the use of gas.

    The article develops cases for making decisions on the necessary investments in the energy system of Ukraine after the war. We analyze energy consumption trends and justify the need for investment in the nuclear industry, which occupies a large part of the country's energy consumption. A model for assessing and forecasting the energy consumption market has been developed. The model shows an upward trend in oil and gas consumption. Our approach allows us to quantify the net increase in energy consumption in the future. 

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  • Public defence: 2024-03-14 09:00 E632, Luleå
    Higashitani, Yuko
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Prediction of traction in EHL contacts operating in the linear isothermal region2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The vehicle industry plays an important role in moving people and goods all over the world. Unfortunately, the vehicular transportation has a huge (negative) impact on the climate. Improved fuel-efficient vehicle technologies are therefore required to reduce emissions and address environmental concerns. The introduction of alternative fuels and the use of high-pressure fuel injection systems in vehicle engines are some of the approaches that are employed to enhance the fuel efficiency of automobiles. However, in the case of high-pressure fuel injection systems, the tribological interfaces such as those of cam–roller followers are subjected to severe operating conditions (including high contact pressures and sliding motion) and consequently high frictional losses and risk of wear-related failures. 

    This thesis’s objective is to establish a prediction formula for the traction coefficient slope to analyze the motion of the roller follower. This prediction formula is derived based on numerical calculations performed using a fully-coupled finite-element based model of the elliptical elastohydrodynamically lubricated contact specifically designed for operational conditions within the isothermal linear regime.

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