RISE – Research Institutes of Sweden
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Sustainable repurpose of end-of-life fiber reinforced polymer composites : A new circular pedestrian bridge concept
No full textIn response to global challenges in resource supply, many industries are adopting the principles of the Circular Economy (CE) to improve their resource acquisition strategies. This paper introduces an innovative approach to address the environmental impact of waste Glass Fiber Reinforced-Polymer (GFRP) pipes and panels by repurposing them to manufacture structural components for new bicycle and pedestrian bridges. The study covers the entire process, including conceptualization, analysis, design, and testing of a deck system, with a focus on the manufacturing process for a 7-m-long prototype bridge. The study shows promising results in the concept of a sandwich structure utilizing discarded GFRP pipes and panels, which has the flexibility to account for variabilities in dimensions of incoming products while still meeting mechanical requirements. The LCA analysis shows that the transportation of materials is the governing contributing factor. It was concluded that further development of this concept should be accompanied by a business model that considers the importance of the contributions from the whole value chain. The authors extend their gratitude to the Swedish Energy Agency(Energimyndigheten) for funding the RECINA project (REuse of Composite parts for INfrastructure Applications – Dnr 2019–021576, Projektnr 49763–1). This project has been made possible through asuccessful collaboration with a Swedish Industrial consortium includingComposite Design, Marstrom¨ Composite, Hitachi-ABB Power Grids,Podcomp, GreenPlank, and Eventhotell.</p
Investigating the trajectory of post-COVID impairments : a longitudinal study in Sweden
No full textIntroduction: Individuals recovering from COVID-19 often experience a range of post-recovery symptoms. However, the literature on post-COVID-19 symptoms reveals conflicting results, necessitating a heightened focus on longitudinal studies to comprehend the trajectory of impairments over time. Our study aimed to investigate changes in long-term impairments among individuals infected with COVID-19 and explore potential predictors influencing these changes. Methods: We conducted a web-survey targeting individuals that had been infected with COVID-19 at four time-points: T0 (baseline), T1 (three months), T2 (six months), and T3 (twelve months). The survey included contextual factors, factors related to body functions and structures, and post-COVID impairments. The longitudinal sample included 213 individuals (with a mean age of 48.92 years). Linear mixed models were employed to analyze changes in post-COVID impairments over time and identify impacting factors. Results: Findings revealed a general decline in post-COVID impairments over time, with each symptom exhibiting a dynamic pattern of fluctuations. Factors such as initial infection severity, education level, and work status were significantly associated with the levels of impairments. Discussion: The study emphasizes that post-COVID impairments are not static but exhibit variations over time. Personalized care, especially for vulnerable populations, is crucial. The results underscore the need for long-term monitoring and multidisciplinary treatment approaches. Targeted support and interventions are highlighted for individuals with severe initial infections and those in socioeconomically disadvantaged groups. The study was financed by grants from the Swedish state under the ALF agreement between the Swedish government and the county councils (Grant No. ALFGBG-983604).</p
Mode I fracture energy release rates of European beech wood-adhesive bonds
No full textThis paper presents mode-I fracture energy release rates (GI) of European beech wood (Fagus sylvatica) adhesive bonds for three common types of adhesives pressed with two levels of pressure and glued with three spread rates. Flat double cantilever beam tests with a shear corrected compliance method were used to derive GI. A high pressing pressure of 1.0 versus 0.1 MPa resulted in higher GI-values for phenol resorcinol formaldehyde and melamine urea formaldehyde adhesive systems (not significant), but did not affect the polyvinyl acetate system. A low adhesive spread rate of 50 g m−2 clearly resulted in lower GI-values for all three systems, while no clear differences were found between spread rates of 100–200 g m−2 for the formaldehyde systems. The herein presented GI-values of beech adhesive bonds can be used to further evaluate the suitability of beech in glued load-bearing timber structures and promote optimising beech wood-adhesive systems for high GI
Investigating immune profile by CyTOF in patients with eosinophilic esophagitis after treatment with orodispersible budesonide
No full textEosinophilic esophagitis (EoE) is a chronic Th2-mediated inflammatory disease of the esophagus driven by dietary or inhalant allergens which if left untreated, leads to fibrosis and poor esophageal function. Although the inflammation in the esophagus is dominated by eosinophils, there are also elevated levels of T and B cells. Blood samples from ten patients with EoE before and after treatment with orodispersible budesonide and 10 healthy controls were compared using cytometry by time-of-flight. An antibody panel was designed that covers the major immunological cell populations with a particular focus on eosinophils. The data was analyzed with multivariate methods and cluster analysis. Correlation analysis was done between immune markers and endoscopic, histological, and symptomatologic assessments. Our analysis revealed that patients with EoE had lower levels of effector memory T cells after treatment with orodispersible budesonide to the same level as healthy subjects. In addition, more suppressive eosinophils were present in the circulation of EoE patients before treatment and more immature eosinophils were present after treatment. Furthermore, levels of galectin-10+ eosinophils correlated with histological findings in esophageal tissue from EoE patients. In all patients, the peak eosinophils were decreased after treatment with orodispersible budesonide. Intriguingly, 90% of the patients had remission in the histological assessment and 50% improved in the endoscopic assessment. This study reports a detailed immune profile in patients with EoE before and after treatment with orodispersible budesonide and it is a step toward finding blood-based immune parameters that could be useful to monitor response to treatment. This study was funded by grants from the Fyrbodal Research and Development Council Region Västra Götaland (identifcation numbers VGFOUREG-980803, 968053, 939998, and 9771279).</p
Evaluation of oxygen delignified fibers with high water absorbency, as a greener alternative to fully bleached fibers for tissue paper
No full textThe potential of oxygen delignified fibers to replace fully bleached fibers in tissue products was investigated on softwood pulps. The absorption, mechanical properties and softness of laboratory tissue hand sheets from one commercial fully bleached pulp and five unbleached oxygen delignified lab pulps were compared. The pulps with different lignin content and total fiber charge were evaluated with and without PFI refining. The pulps subjected to oxygen delignification resulted in pulps with much higher total fiber charge content that led to higher swelling and higher wet strength when compared to the commercial fully bleached pulp. Some unbleached oxygen delignified pulps showed great potential in the absorption capacity, while others showed a much higher wet tensile strength when compared to the commercial pulp. Compared to the commercial bleached pulp, a similar softness for a higher wet and dry tensile index in the unbleached fibers was observed for the oxygen delignified pulps. Unbleached pulps subjected to an extended oxygen delignification proved to be a suitable alternative to fully bleached pulps in tissue grades, depending on the desired property (absorption or wet strength). Södra Skogsägarnas Stiftelse för Forskning,Utveckling och Utbildning, 2022–297.</p
Amide groups in 3.7 billion years old liquid inclusions
No full textCarbon with depleted d13C (down to − 25.6‰ VPDB) found in > 3.7 billion year old metamorphic sediments from the Isua Supracrustal Belt, Southwestern Greenland, has been proposed to represent the oldest remains of life on Earth. Graphitic inclusions within garnet porphyroblasts from this locality have been shown to associate with elements consistent with biogenic remains. In this report, we focus on certain liquid inclusions found in the Isua garnets, characterizing their chemical composition using atomic force microscopy, AFM-based infrared spectroscopy, optical photothermal infrared spectroscopy, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry. Our results show that the liquid inclusions contain functional groups consisting of carbon, nitrogen, and oxygen in a configuration similar to amide functional groups. We suspect that the amide groups formed from N, O and C-containing volatile components that were released from the original kerogenous material enclosed in the garnets, as this was graphitized during thermal maturation. This is consistent with the observed inclusion assemblage of solid graphitic and viscous fluid inclusions alike. Our observations are compatible with the inclusions forming from biogenic precursor material, and when considered alongside previous reports on the carbonaceous material in the Isua metamorphic sediments, these and our study collectively indicate that the carbonaceous material in the Isua metasediments represents the oldest traces of life on Earth. This project was made possible through financial support provided by the Novo Nordisk foundation through the NERD program, grant number NNF21OC0068372 given to TH. SS was supported by Swedish National Space Agency (Contracts 137/19 and 2021- 00092).</p
Additive manufacturing of aluminum Al 6061 alloy using metal injection molding granules : green density, surface roughness, and tomography study
No full textIn the present study, a metal injection molding (MIM) feedstock of aluminum Al 6061 was used as the raw material for extrusion 3D printing and sintering-based AM. A design of experiments methodology was used to systematically analyze the individual and interactive effects of various parameters, such as extrusion temperature, extrusion flow rate multiplier, nozzle printing speed on the green density, and surface roughness. MIM feedstock resulted in shear-thinning behavior as required for extrusion printing. The initial findings revealed a decrease in green density with an increase in nozzle speed, whereas a contrasting trend was observed with a reduction in the extrusion flow rate. A similar trend was observed for the surface roughness measured along the printing direction. Through the application of regression equations and a multi-objective optimization technique, the study achieved the dual objectives of maximizing the green density and minimizing the surface roughness. To comprehensively evaluate the manufactured components, microtomography analysis was conducted on specimens produced under optimized parameters and randomly selected conditions. Subsequently, the specimens underwent debinding and sintering processes to obtain the sintered metal parts. However, sintering results in poor densification, which requires further investigation. The investigations provided valuable insights into optimizing the production of green parts endowed with higher density and better surface characteristics by leveraging extrusion 3D printing of aluminum Al 6061 MIM feedstock. The authors thank the Institute Carnot Energies du Futur for their fnancial support in this work (21U12—PRIMALU).</p
Combining Magnetostriction with Variable Reluctance for Energy Harvesting at Low Frequency Vibrations
No full textIn this paper, we explore the benefits of using a magnetostrictive component in a variable reluctance energy harvester. The intrinsic magnetic field bias and the possibility to utilize magnetic force to achieve pre-stress leads to a synergetic combination between this type of energy harvester and magnetostriction. The proposed energy harvester system, to evaluate the concept, consists of a magnetostrictive cantilever beam with a cubic magnet as proof mass. Galfenol, Fe81.6Ga18.4, is used to implement magnetostriction. Variable reluctance is achieved by fixing the beam parallel to an iron core, with some margin to create an air gap between the tip magnet and core. The mechanical forces of the beam and the magnetic forces lead to a displaced equilibrium position of the beam and thus a pre-stress. Two configurations of the energy harvester were evaluated and compared. The initial configuration uses a simple beam of aluminum substrate and a layer of galfenol with an additional magnet fixing the beam to the core. The modified design reduces the magnetic field bias in the galfenol by replacing approximately half of the length of galfenol with aluminum and adds a layer of soft magnetic material above the galfenol to further reduce the magnetic field bias. The initial system was found to magnetically saturate the galfenol at equilibrium. This provided the opportunity to compare two equivalent systems, with and without a significant magnetostrictive effect on the output voltage. The resonance frequency tuning capability, from modifying the initial distance of the air gap, is shown to be maintained for the modified configuration (140 Hz/mm), while achieving RMS open-circuit coil voltages larger by a factor of two (2.4 V compared to 1.1 V). For a theoretically optimal load, the RMS power was simulated to be 5.1 mW. Given the size of the energy harvester (18.5 cm3) and the excitation acceleration (0.5 g), this results in a performance metric of 1.1 mW/cm3g2.This work received funding from Swedish Foundation for Strategic Research in the program for "Research Institute PhD" (grant no. FID16-0055) and from ECSEL Joint Undertaking (JU) project "Energy ECS" (grant no. 101007247). The APC was funded by RISE Research Institutes of Sweden AB.</p
From AI Act to Structured Testing of AI Systems
No full textThe Citcom.AI RISE testing approach is a step towards structured AI system evaluation and testing under the AI Act's regulatory framework. It establishes a definition of context in the scenario of different AI application domains, AI subfields, and use cases. In particular, a systematic evaluation, from defining the context and application to detailed risk assessments, linking each AI application to corresponding testing standards and methodologies, is presented. The approach translates AI Act’s high level regulatory requirements for different AI system risk levels to appropriate technical testing techniques for achieving trustworthiness across different domains and AI subfields, promoting responsible AI deployment and fostering trust in AI applications.
Investigation of Threshold Voltage Instability and Bipolar Degradation in 3.3 kV Conventional Body Diode and Embedded SBD SiC MOSFET
No full textThe 3.3 kV SiC MOSFETs are essential for traction applications, so it is important to investigate the reliability of the recently developed high voltage MOSFETs and power modules as they are believed to be more susceptible to the effects of basal plane dislocations (BPDs). This paper presents measurement results and analysis of bipolar degradation and threshold voltage instability in 3.3 kV SiC MOSFETs having two distinct kinds of integrated diode, conventional body diode and embedded Schottky Barrier Diode (SBD). No bipolar degradation was observed both in MOSFET with conventional body diode and with embedded SBD after accumulated test with 100 hours each of 200%, 400% and 600% rated current stress in the 3rd quadrant of operation. However, the output characteristics show 1% ( 0.2 mΩ) and 2% ( 0.4 mΩ) increase in on resistance (RDS(on)) and 11% (0.23 V) and 5% (0.1 V) increase in threshold voltage (VTH), respectively, after total bipolar degradation test in the case of the MOSFET with conventional body diode and up to 74 hrs of 600% rated current stress in the case of the MOSFET with embedded SBD at 70°C. A rapid large negative VTH shift was obse rved in the MOSFETs with embedded SBD after 74 hrs of 600% rated current stress. After accumulated Bias Temperature Instability (BTI) test at 150°C, the VTH value at 25°C has increased by 9.7% (0.14 V) and 14.5% (0.2 V) for the MOSFET with conventional body diode and with embedded SBD, respectively, while RDS(on) increased by 1mΩ at 25°C and by 5mΩ at 150°C, for both types of MOSFETs.This work is supported by the European Union\u2019s Horizon 2020 research and innovation programme under grant agreement no 101015423 (project Recet4Rail) and by the EU KDT JU under grant agreement no 101096387 (project PowerizeD). The Future Power Electronics project at RISE is also acknowledged for financial support and Mitsubishi Electric for supplying engineering samples used in this investigation.</p