Luleå University of Technology Publications
Not a member yet
39356 research outputs found
Sort by
Constructing Poly(Ionic Liquid)s-Based Solid State Electrolytes and Application in Lithium Metal Batteries
No full textLithium metal batteries (LMBs) are attracting attention for their potential to enhance energy density while offering safety over conventional Li-ion batteries (LIBs) with flammable liquid organic electrolytes. However, realizing LMBs presents a formidable challenge, and developing compatible and effective solid-state electrolytes (SSEs) has been proposed as one effective strategy to address the challenge. SSEs are typically classified into inorganic solid electrolytes (ISEs), solid polymer electrolytes (SPEs), and solid composite electrolytes (SCEs), while each type has inherent limitations that prevent them from forming an ideal SSE. The SSEs using polymer are promising in further development owing to the capabilities of the polymer in facilitating Li+ transport and enabling the operation of LMBs with high-voltage cathodes. However, the current polymers in LMBs suffer from poor high-voltage stability, making it challenging to achieve long cycle life. Poly(ionic liquid)s (polyILs), a new type of polymer that incorporates the properties of ionic liquids (ILs), including wide electrochemical stability window (ESW) and high ionic conductivity, into polymer frameworks, offer a promising alternative to the traditional polymers in SSEs. This thesis aims to develop polyIL-based SSEs with enhanced ionic conductivity, a wide ESW, a high lithium transference number (tLi+), reduced electrodes/electrolyte interface resistance, and suppression of lithium dendrites growth, ultimately enabling LMBs with extended cycle life. These objectives are achieved by tuning the constituents of the polyIL-based SSEs. The specific achievements of this thesis are as follows: 1. The application of ILs in SSEs and their effects on LMB performance were reviewed and summarized. The analysis highlighted that ILs can improve ionic conductivity, broaden the ESW of electrolytes, and enhance interface contact between the electrode and electrolyte. Considering the overall performance of ILs, including high ionic conductivity, a wide ESW, and cost-effectiveness, EMIMTFSI was selected for subsequent experiments. 2. Three F-based Li-salts were selected to prepare SSEs using poly(ethylene oxide) host and polyimide substrate. The investigation focused on the impact of F content and chemical structures (F-connecting bonds) of these Li-salts on the cell performance and uncovering the formation process of LiF in the solid electrolyte interphase (SEI). The results revealed that the F-connecting bond plays a more significant role than the F element content, resulting in slightly better cell performance using LiPFSI than LiTFSI and substantially better performance than LiFSI. The preferential breakage of bonds in LiPFSI was found to be related to its position to the Li anode. Consequently, the LiPFSI reduction mechanism was proposed. 3. Using the template method, a polyIL-based SCE was synthesized with boron nitride (BN) nanosheets as inert inorganic fillers. BN was chosen due to its high specific surface area and porous structure. An optimal BN content of 1.6 wt% was found to increase the amorphous regions of the polyIL, facilitating Li+ migration, and enhancing both tLi+ and ionic conductivity. The Li//LiFePO4 cell assembled with the optimized SCE delivered a stable capacity of up to 152 mA h g−1 after 300 cycles. 4. A concentration gradient poly(ionic liquid) (polyIL)-based SCE (GSCE) was synthesized via natural sedimentation and photopolymerization to simultaneously meet the distinct requirements of both the cathode and the lithium metal anode. The concentration of active inorganic filler was optimized, with 5 wt% as the optimal content. Compared to the uniform SCE, the GSCE demonstrated a higher tLi+ and improved ionic conductivity. As a result, the Li/GCSE-5/LMFP cell operated at a cut-off voltage of 4.3 V and exhibited a long cycle life. 5. A polyIL-based SSE was developed by combining a polyIL material host with a modified cellulose acetate (CA)-polyIL substrate to enrich diverse functional groups. This design effectively mitigated the non-uniform filler distribution within the polymer host while maintaining high mechanical strength and facilitating the Li+ migration. Additionally, the use of the same polyIL-based material as a cathode binder significantly improved their interfacial compatibility. As a result, the developed LMB demonstrated stable operation at a high cut-off voltage of 4.8 V and an extended cycle life
Cloud-based IoT and Collaborative Learning for Cyber-Physical System of Systems
No full textThe growth in cyber-physical systems (CPS), the industrial internet of things (IIoT) and integrations of machine learning (ML) models have enabled Industry 4.0 automation and intelligence in industrial System of Systems (SoS). However, scalable automation frameworks, dynamic interoperability for smooth communication among heterogeneous systems, and the integration of ML models particularly for online collaborative intelligence in distributed architectures, are open challenges that must be addressed. This thesis structures its research as a progressive investigation, with each identified challenge leading to the next. First, local cloud-based automation is explored using the Eclipse Arrowhead framework to propose digitalization frameworks for industrial use cases, such as predictive maintenance in wind energy systems and smart manufacturing. The primary objective is to bridge the digital divide in SoSs environments, ensuring seamless intercommunication between IoT-connected devices. Significant engineering effort is dedicated to developing dynamically scalable automation solutions that integrate heterogeneous CPS, providing real-time adaptability and efficiency. This leads to the second research challenge addressed in this thesis. To investigate the challenge of semantic interoperability among heterogeneous IIoT devices, this research explores ontology alignment techniques through Natural Language Processing (NLP) and deep learning models. Extension of an existing language model (BERT_Intereaction) is proposed for ontology graphs to facilitate seamless communication between heterogeneous IIoT devices. It is designed using a language encoder to develop knowledge of the text to understand the labels or entities and a structural encoder to understand the context or semantics behind the text. This proposed model consistently outperforms cross-lingual tasks over the state-of-theart techniques with an error reduction of 2.1% on benchmark datasets DBP15KZH−EN, DBP15KJA−EN, and DBP15KFR−EN. The third challenge involves scaling collaborative intelligence across distributed IioT systems. To address this, a local cloud-based collaborative learning (CCL) model is designed for the service-oriented architecture (SOA) and a decentralized ML model to digitalize IIoTs while enabling ML-based optimizations for IIoT tasks across cloud and edge nodes. The CCL model integrates machine learning-as-a-service (MLaaS) into the distributed cloud architectures. CCL offers scalable, privacy-driven, self-contained local clouds for every CPS in the system of systems model. The local clouds enable distributed ML deployment across the IIoT SoS, where devices collaborate to share their knowledge representations. The model uses unsupervised dictionary learning, allowing IIoT nodes to share compressed, optimized learning representations. Furthermore, this thesis also highlights a culminating issue for designing decentralized ML-enabled IIoT solutions that is the information overload and redundancy at the edge and cloud. To mitigate this challenge, the CCL+ model is proposed, integrating coherence-based dictionary refinement with Bayesian optimization. The model is tested on the condition monitoring task using data from an automated farm of six wind turbines using the CCL model. Implementing redundancy-aware strategies in the CCL+ optimized bandwidth usage and reduced communication overhead, especially for the resource-constrained IIoT devices. In the simulation experiments, over one year, the propagated learned dictionary size at a single wind turbine exceeded 1 petabyte. In contrast, in comparison, using the CCL+ model, for the same duration, the learned dictionary remained at 18 MB, significantly enhancing communication and computational efficiency without losing essential information. Various potential future research directions accompany the findings presented in this thesis. For instance, to strengthen the ablation study on the semantic interoperability among heterogeneous SoS challenge, a generalized IIoT ontology that is designed for any IoT device (beyond sensors), such as the smart applications reference ontology (SAREF) can be tested for ontology alignment. This work provides a step towards enabling translation between heterogeneous IoT sensor devices. The proposed BERT Intereaction model can be further extended to a translation module using the generalized ontology graphs. Then investigations can be conducted to test if the model can interpret the messages transmitted across ontologically different devices in two scenarios: a) where the ontology graphs of both devices are a subset of the generalized ontology graph, and b) they are overlapping graphs and may contain different nodes and relations but they are semantically the same. Furthermore, exploring the utility of CCL+ model for extended large-scale SoS with multiple parallel tasks to test the collaborative learning concept across the heterogeneous cyber-physical system of systems (CPSoS)
Emerging Role of 2D Materials in Photovoltaics: Efficiency Enhancement and Future Perspectives
No full textThe growing global energy demand and worsening climate change highlight the urgent need for clean, efficient and sustainable energy solutions. Among emerging technologies, atomically thin two-dimensional (2D) materials offer unique advantages in photovoltaics due to their tunable optoelectronic properties, high surface area and efficient charge transport capabilities. This review explores recent progress in photovoltaics incorporating 2D materials, focusing on their application as hole and electron transport layers to optimize bandgap alignment, enhance carrier mobility and improve chemical stability. A comprehensive analysis is presented on perovskite solar cells utilizing 2D materials, with a particular focus on strategies to enhance crystallization, passivate defects and improve overall cell efficiency. Additionally, the application of 2D materials in organic solar cells is examined, particularly for reducing recombination losses and enhancing charge extraction through work function modification. Their impact on dye-sensitized solar cells, including catalytic activity and counter electrode performance, is also explored. Finally, the review outlines key challenges, material limitations and performance metrics, offering insight into the future development of next-generation photovoltaic devices encouraged by 2D materials.Validerad;2025;Nivå 2;2025-10-02 (u5);Full text license: CC BYFor funding information, see: https://link.springer.com/article/10.1007/s40820-025-01869-z#Fun</p
Field Performance of an EcoVault Facility for Stormwater Quality Treatment
No full textAs urbanization accelerates, stormwater management in cities has shifted from focusing strictly on water quantity to addressing water quality. Traditionally implemented systems, such as stormwater ponds, while offering effective solutions, often require large land areas to implement, making them impractical for dense urban environments. Underground stormwater systems, like EcoVault, offer a more compact solution; however, they lack scientific studies under real-world conditions to prove their effectiveness in treating pollutants. This study evaluates the treatment performance of two parallel EcoVault systems with the same design, consisting of a sedimentation step and a filtration step. These facilities were retrofitted into two different stormwater sewer networks draining two urban catchments. The systems were assessed for their ability to treat total suspended solids, metals, nutrients, and organic pollutants from urban runoff. Over 15 rain events, the average total suspended solids (TSS) removal rate was 40% for EcoVault A and 46% for EcoVault B. The removal rates for metals varied, with EcoVault B showing better performance for average metal treatment (53% for Cu and 58% for Zn). However, neither EcoVault system removed dissolved metals, often with an increase of dissolved metal concentration in the effluent. The filtration step did not contribute to pollutant treatment, likely due to clogging and high hydraulic loading rates. The study highlighted the potential of underground stormwater treatment in areas with limited space availability, while identifying challenges such as treatment of dissolved pollutants.Validerad;2025;Nivå 1;2025-11-11 (u2);Full text: CC BY license;This article has previously appeared as a manuscript in a thesis.</p
Varieties of disagreement in transformative policy missions: A Q study on the decarbonization of Swedish industry
No full textGovernments increasingly launch transformative policy missions to address complex societal challenges such as climate change. While the literature on mission-oriented innovation policy highlights the role of stakeholder contestation and emphasizes the need to promote alignment, it often overlooks the nature of underlying disagreements. This paper distinguishes between factual and normative disagreement across problems, solutions, and interventions, and applies Q methodology to identify and analyze four distinct stakeholder narratives in the mission to decarbonize Swedish industry. The narratives reveal different varieties of disagreement, ranging from factual concerns about technological feasibility and policy effectiveness to normative critiques of directionality and legitimacy. Our findings demonstrate that missions involve not only alignment, but also disjointment – persistent divergences of opinion rooted in fundamentally conflicting values and beliefs. Recognizing disjointment underscores the need for mission-oriented policymaking to balance efforts to foster alignment with strategies that address enduring conflict through mediation, recognition, redistribution, and compensation. Validerad;2025;Nivå 2;2025-11-18 (u8);Full text license: CC BY</p
Deformation of surrounding rocks in salt caverns in compressed air energy storage plants: Insights from laboratory experiments and numerical simulations
No full textThe long-term mechanical stability of surrounding rock in compressed air energy storage (CAES) salt caverns is crucial for the safe and efficient operation of underground energy systems. In this study, the deformation behavior of salt rock was investigated through a combined approach that involved long-term laboratory creep–fatigue tests and engineering-scale numerical simulations. Mechanical experiments were carried out at various cyclic stress levels and loading rates to replicate the creep–fatigue loading conditions that are encountered during CAES operations. The results indicate that both the magnitude and the frequency of cyclic loading significantly influence the time-dependent deformation of salt rock: higher stress levels accelerate damage, whereas lower loading rates lead to increased plastic strain. On the basis of the geological conditions of a planned CAES facility, numerical simulations were conducted using FLAC3D. The model incorporates the Norton creep law to simulate the evolution of the surrounding rock with different numbers of operational cycles and gas pressures. The operating pressure and frequency significantly affect the deformation and plastic zone distribution of the surrounding rock in salt cavern reservoirs. Higher operational frequencies and minimum gas pressures result in reduced deformation and improved cavern stability. For the first time, a direct qualitative analysis was conducted to compare the laboratory experiments and numerical simulation results. Comparative analysis reveals that the experimental and simulation results are generally consistent. These findings offer new insights into the mechanical response of salt cavern-surrounding rock and establish a foundation for predicting the long-term performance of CAES systems.Full text license: CC BY 4.0;Funder: Rut and Sten Brand foundation; National Natural Science Fund of China (52274073); Chongqing Youth Innovative Talent Project (CSTB2024NSCQ-QCXMX0022); Chongqing Natural Science Foundation Innovation and Development Joint Fund (CSTB2024NSCQ-LZX0056); Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety (SKLGGES-024006)</p
Pedagogical Tact Insights in Online Learning Communities
No full textThe growing reliance on AI-powered EdTech solutions has prompted educators at all levels to rethink teaching and learning methodologies. This shift has fostered a renewed partnership among teachers, students, and society, repositioning AI from a passive support tool into a proactive agent in the classroom. This transformation calls for teachers to exercise leadership and judgement in guiding students’ use of AI, emphasising both responsible practices and ethical considerations within their broader socio-cultural contexts. To harness this potential, we leveraged AI-based solutions within the AECT academic association to reinterpret UNESCO’s four foundational pillars of learning, thereby impacting the broader educational community. This initiative underscores literacy in educational communities emerging from intra-national and international inequity. Hence, it is imperative to examine the exigency of fundamental rights in relation to ethics and norms to uphold the innovative opportunities of AI in education globally. In this regard, this study connects the Pedagogical AI-Tact concept to bridge the gap between theory and practice, fostering both interest and ethical engagement across diverse educational communities. This study valuably upholds Margaret Mead’s proposal that every child deserves universal educational rights, a principle in harmony with justice and freedom.Full text license: CC BY</p
Regional Three-Dimensional Magnetotelluric Electrical Resistivity Model of the Manica Greenstone Belt, Western Mozambique
No full textMagnetotelluric (MT) survey results from the Late Archean Manica greenstone belt, an extension of the Odzi-Mutare greenstone belt of the Zimbabwe Craton, are presented. A total of 33 MT stations were acquired on an irregular grid with an average station spacing of approximately 5 km. This data set represents the first MT survey in Mozambique. The results from the 3-D modeling indicate a conductive mid-crustal structure in the central part of the surveyed greenstone belt and the presence of narrow sub-vertical conductive structures connecting the mid-crustal conductor with shallow structures. These sub-vertical conductive structures are tentatively interpreted as marking the location of fluid pathways for mineralizing fluids associated with gold occurrences. The modeled mid-crustal conductor mapped in the Manica greenstone belt does not have a western continuation toward the adjacent Odzi-Mutare greenstone belt in Zimbabwe.Full text license: CC BY-NC</p
Klimatoptimering av betongstommar: utmaningar och möjliggörare för hållbart byggande
No full textBygg- och fastighetssektorn står inför stora utmaningar när det gäller att minska klimatpåverkan i enlighet med nationella och globala klimatmål. Tack vare att stommen i flerbostadshus utgör omkring 60% av klimatavtrycket under byggskedet (A1–A5) finns stor potential att reducera utsläppen genom olika former av optimering. Denna studie syftar till att undersöka hur optimering av stomkonstruktioner i flerbostadshus av betong kan bidra till att minska klimatpåverkan i byggskedet, samt att analysera hur olika optimeringsstrategier påverkar projektets kostnader. Studien avser dessutom att undersöka betydelsen av innovation av betongen för fortsatt reduktion av koldioxidutsläpp inom bostadsbyggandet. Studien genomfördes i samarbete med Peab och baseras på tre olika delstudier, inledningsvisen litteraturstudie vilken mynnade ut i studiens tre forskningsfrågor. Därefter gjordes två andra delstudier, benämnt delstudie 1 och 2 bestående av intervjuer och studiebesök samt en klimatkalkyl av koncepthuset NärBo. Totalt genomfördes sju intervjuer med aktörer från olika delar av branschen samt tre studiebesök hos relevanta verksamheter. Klimatkalkylen analyserade olika optimeringsalternativ där materialval och dimensioner varieras.Resultaten visar att det finns en stor outnyttjad potential att reducera klimatpåverkan genom mer nyanserade materialval och anpassade dimensioner, men att traditioner och invanda processer ofta leder till överdimensionering och standardiserade lösningar. Produktionsstrategin har också betydande inverkan, där prefabricering kan bidra till lägre utsläpp men även medföra ekonomiska och logistiska utmaningar. Klimatkalkylen indikerar att kombinerad material- och dimensionsoptimering kan uppnå en betydande reducering av stommens klimatpåverkan, men att vissa åtgärder bland annat kan leda till ökade kostnader,förlängd byggtid. Innovation, både i form av nya produkter och processer, belyses vara en nyckelfaktor för att möjliggöra en fortsatt klimatreduktion, men är beroende av drivkrafteroch möjliggörare såsom kundkrav, regelverk, kapital och samarbete mellan aktörer.Studiens slutsats är att klimatoptimering av betongstommar kräver en balans mellan klimatpåverkan, kostnad och produktionseffektivitet. För att åstadkomma långsiktiga förbättringar behöver branschen utveckla nya arbetssätt där konstruktörer involveras tidigare i processen, materialval görs mer situations anpassat och innovationsarbete ges utrymme och incitament. Vidare forskning föreslås kring fördjupade studier av dimensioneringsoptimeringens praktiska potential. Även geografiska skillnader och möjligheter till en materialoptimering med fokus på cementinnehåll samt vidare studier av optimeringens helhetsperspektiv. AbstractThe construction and real estate sector faces major challenges in reducing climate impact in accordance with national and global climate goals. Since the structural frame of multi-family buildings accounts for about 60% of the climate footprint during the construction phase (A1–A5), there is great potential to reduce emissions through various forms of optimization. This study aims to investigate how material, dimension, and production optimization of concrete frames can contribute to reduced climate impact, as well as analyze how these measures affect project costs. Furthermore, the study examines the challenges and enablers of innovation for continued emission reduction.The study was conducted in collaboration with Peab and is based on three different substudies consisting of a literature review, interviews, site visits, and a climate calculation of the concept building NärBo. A total of seven interviews were conducted with stakeholders from different parts of the industry, as well as three site visits to relevant operations. The climate calculation analyzed various optimization alternatives where material choices and dimensions were varied.The results show that there is significant untapped potential to reduce climate impact through more nuanced material choices and adapted dimensions, but that traditions and established processes often lead to over-dimensioning and standardized solutions. The production strategy also has a significant impact, where prefabrication can contribute to lower emissions but also entail economic and logistical challenges. The climate calculation indicates that combined material and dimension optimization can achieve a significant reduction in the climate impact of the frame, but that certain measures can, among other things, lead to increased costs and extended construction time. Innovation, both in the form of new products and processes, is highlighted as a key factor in enabling continued climate reduction, but is dependent on drivers and enablers such as customer requirements, regulations, capital, and collaboration between stakeholders.The study concludes that climate optimization of concrete frames requires a balance between climate impact, cost, and production efficiency. To achieve long-term improvements, the industry needs to develop new working methods where designers are involved earlier in the process, material choices are made more situationally, and innovation work is given space and incentives. Further research is suggested on in-depth studies of the practical potential of dimension optimization. Also, geographical differences and opportunities for material optimization with a focus on cement content, as well as further studies of the overall perspective of optimizatio
Adult patients’ experiences of healthcare encounters in somatic care when living with mental illness
No full textVuxna personer med psykisk ohälsa har en ökad risk för somatisk samsjuklighet och för tidig död, vilket ställer krav på en jämlik och personcentrerad somatisk vård. I somatisk vård blir dessa personer patienter, och vårdmöten är centrala för möjligheten till adekvat behandling, uppföljning och patientdelaktighet. Syftet med denna litteraturstudie var att beskriva vuxna patienters erfarenheter av vårdmöten inom somatisk vård vid psykisk ohälsa. Studien genomfördes som en kvalitativ litteraturstudie. Systematiska litteratursökningar genomfördes i PubMed och CINAHL. Tolv originalartiklar med kvalitativ ansats inkluderades. Artiklarna kvalitetsgranskades med SBU:s (2022) granskningsmall för kvalitativa studier och analyserades med kvalitativ innehållsanalys enligt Bengtsson (2016). Analysen resulterade i fem kategorier: att inte bli lyssnad på och uppleva begränsad delaktighet i vården, att bristande kommunikation och otydlig information skapar osäkerhet, att uppleva stigma och misstro i mötet med vårdpersonal, att kontinuitet och stabila vårdrelationer skapar långsiktigt förtroende samt att mötas med empati och respekt skapar trygghet och tillit. Resultatet visade att vuxna patienter med psykisk ohälsa ofta upplevde att deras symtom inte togs på allvar i den somatiska vården, vilket kunde bidra till otrygghet, fördröjt vårdsökande och risk för uteblivna adekvata medicinska insatser. Samtidigt framkom att tydlig kommunikation, empatiskt bemötande och kontinuitet i vårdrelationer var avgörande för att stärka delaktighet och tillit. Slutsatsen var att vuxna patienters erfarenheter av vårdmöten inom somatisk vård påverkar både vårdens utfall och benägenhet att söka vård. Sjuksköterskan har en central roll i att främja personcentrerad omvårdnad, motverka stigma och bidra till att både psykiska och somatiska behov uppmärksammas på jämlika villkor. Nyckelord: vårdmöten, erfarenheter, delaktighet, kontinuitet, psykisk ohälsa, somatisk vård, stigm