RISE – Research Institutes of Sweden
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Assessment of the in-plane capacity of masonry walls with the Hybrid Discrete-Finite Element Method
No full textThe most widespread numerical simulation method for structural response is undoubtedly the Finite Element Method (FEM). However, despite being powerful for modelling continuous structures, it is not fit for handling strong discontinuities. The Discrete Element Method (DEM) simulates interactions between rigid or deformable elements in contact, hence explicitly capturing the discontinuous nature of the structural response, particularly when subjected to extreme loadings. Nevertheless, it requires a time-stepping algorithm even for solving static or buckling problems. The Hybrid Discrete-Finite Element Method, shortly HybriDFEM, was recently introduced in the context of modelling one-dimensional beam-like members. Those members are divided along their longitudinal axis in a series of rectangular rigid blocks, and the deformation is concentrated at the interfaces between adjacent blocks, modelled as distributed nonlinear multidirectional springs. The method, developed within a FEM-like setting, allows for hybridisation with other finite elements (e.g., beam elements). Next to its ability to explicitly model pre-existing discontinuities along the member (e.g. masonry stereotomy), the method can be used for modelling continuous members with satisfactory accuracy by appropriately scaling the interface springs. As such, the HybriDFEM’s formulation can accommodate hybrid discrete-continuous systems. In this paper, the HybriDFEM formulation is extended to 2D, with rectangular blocks in contact on all four faces. First, the algorithm to detect blocks in contact will be explained. Second, specific characteristics of the HybriDFEM applied to masonry modelling are presented. Then, the method is benchmarked against a two-dimensional problem from the literature where the in-plane capacity of walls made masonry blocks is investigated
Experimental Investigation of Water-Based Fire Suppression Systems on External Facade Fires
No full textThe use of external fire suppression systems can reduce the risk of fire spreading between buildings. This study investigated the effectiveness and efficiency of different externally placed water-based fire suppression systems on façade fire safety. A series of large-scale experiments comprising an SP Fire 105 setup equipped with sprinklers and high-pressure water mist nozzles have been performed. A combustible facade, consisting of 2.5 cm thick oriented strand board (OSB) plates, was installed to provide challenging conditions and allow a visual assessment of the post-fire damage. The temperature profile on the façade surface was measured with 34 thermocouples, while five heat flux gauges and two fast-response plate thermocouples were used to measure the heat flux on the facade surface and emitted to the ambient. The sprinklers and the high-pressure water mist system effectively suppressed the upwards flame migration and reduced the heat flux toward adjacent buildings. It was observed that the sprinklers acted as a water curtain and kept the facade wet during the fire, promoting minor damage (the burnt area is less than 1% of the total area). The temperature and heat flux measurements demonstrated that the sprinkler system was the most effective suppression system. However, the high-pressure water mist systems achieved similar effectiveness but a much higher efficiency concerning water consumption. The sprinkler nozzles used four times as much water as the high-pressure water mist nozzles. Open access funding provided by RISE Research Institutes of Sweden. This research is with the support from the Fire Research and Innovation Centre (FRIC), funded by the Research Council of Norway (No. 294649), and the partners of FRIC.</p
Optimizing Wind Farm Efficiency through Active Yaw Control : A Neural Network-Aided Game Theory Approach
No full textThis research investigates the potential of a game-theoretic-based Active Yaw Control (AYC) strategy to enhance power generation in wind farms. The proposed AYC strategy in this study replaces traditional look-up tables with a trained Artificial Neural Network (ANN) that determines the optimal yaw misalignment for turbines under time-varying atmospheric conditions. The study examines a hypothetical 3x2 rectangular arrangement of NREL 5-MW wind turbines. The FAST.Farm simulation tool, utilizing the dynamic wake meandering (DWM) model, is employed to assess both the power performance and structural load on the wind turbines. When tested with two different inflow directions and ambient turbulence (10%), the AYC strategy demonstrated a maximum increase in total power output of 2.6%, although it affected individual turbines differently. It also exhibits an increase in some structural loads, such as tower-top torque, while some components experience a slight reduction in load. The results underscore the effectiveness of the ANN-guided game-theoretic algorithm in improving wind farm power generation by mitigating the negative impact of wake interference, offering a scalable and efficient method for optimizing large-scale wind farm. However, it is essential to evaluate the overall impact of AYC on wind farm efficiency in terms of both Annual Energy Production (AEP) and structural loading under various atmospheric conditions. This research was conducted within the framework of the VindEl program and received funding from the Swedish Energy Agency (Energimyndigheten) under the grant No. 2021-029520. </p
Mapping the landscape of circular design tools
No full textCircular design tools can help companies to move from linear to circular design practices and an increased uptake of such tools have potential to help realise the circular transition. Despite the existence of numerous circular design tools, companies often find it challenging to identify tools that align with their needs as the tool landscape is difficult to navigate. This paper offers a synthesized overview of 65 circular design tools that uniformly describes the tools’ main attributes. The tools are categorized into five families to make it easier to navigate the tool landscape and identify tools for specific needs. The findings offer a useful resource for the research community as well as companies seeking to e.g. design for value retention and extended product lifetimes. Implications for tool developers and practitioners are highlighted, advocating for more effective utilization of existing tools and the alignment of future tool development with circular design practices.
Influence of Hardwood Lignin Blending on the Electrical and Mechanical Properties of Cellulose Based Carbon Fibers
No full textCarbon fibers (CFs) are fabricated by blending hardwood kraft lignin (HKL) and cellulose. Various compositions of HKL and cellulose in blended solutions are air-gap spun in 1-ethyl-3-methylimidazolium acetate (EMIM OAc), resulting in the production of virtually bead-free quality fibers. The synthesized HKL-cellulose fibers are thermostabilized and carbonized to achieve CFs, and consequently their electrical and mechanical properties are evaluated. Remarkably, fibers with the highest lignin content (65%) exhibited an electrical conductivity of approximately 42 S/cm, surpassing that of cellulose (approximately 15 S/cm). Moreover, the same fibers demonstrated significantly improved tensile strength (∼312 MPa), showcasing a 5-fold increase compared to pure cellulose while maintaining lower stiffness. Comprehensive analyses, including Auger electron spectroscopy and wide-angle X-ray scattering, show a heterogeneous skin-core morphology in the fibers revealing a higher degree of preferred orientation of carbon components in the skin compared to the core. The incorporation of lignin in CFs leads to increased graphitization, enhanced tensile strength, and a unique skin-core structure, where the skin’s graphitized cellulose and lignin contribute stiffness, while the predominantly lignin-rich core enhances carbon content, electrical conductivity, and strength.Project 4.1.4 financially supported by the Knut andAlice Wallenberg Foundation of Sweden and the support of theEuropean Research Council (ERC) under the EuropeanUnion’s Horizon 2020 Program EU Horizon 2020 ProjectGreEnergy for this work.</p
Characterizing Hydrated Sulfates and Altered Phases in Jezero Crater Fan and Floor Geologic Units With SHERLOC on Mars 2020
No full textThe Mars 2020 Perseverance rover has explored fluvio-lacustrine sedimentary rocks within Jezero crater. Prior work showed that igneous crater floor Séítah and Máaz formations have mafic mineralogy with alteration phases that indicate multiple episodes of aqueous alteration. In this work, we extend the analyses of hydration to targets in the Jezero western fan delta, using data from the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) Raman spectrometer. Spectral features, for example, sulfate and hydration peak positions and shapes, vary within, and across the crater floor and western fan. The proportion of targets with hydration associated with sulfates was approximately equal in the crater floor and the western fan. All hydrated targets in the crater floor and upper fan showed bimodal hydration peaks at ∼3,200 and ∼3,400 cm−1. The sulfate symmetric stretch at ∼1,000 cm−1 coupled with a hydration peak at ∼3,400 cm−1 indicate that MgSO4·nH2O (2 < n ≤ 5) is a likely hydration carrier phase in all units, perhaps paired with low-hydration (n ≤ 1) amorphous Mg-sulfates, indicated by the ∼3,200 cm−1 peak. Low-hydration MgSO4·nH2O (n = 1–2) are more prevalent in the fan, and hydrated targets in the fan front only had one peak at ∼3,400 cm−1. While anhydrite co-occurs with hydrated Mg-sulfates in the crater floor and fan front, hydrated Ca-sulfates are observed instead at the top of the upper fan. Collectively, the data imply aqueous deposition of sediments with formation of salts from high ionic strength fluids and subsequent aridity to preserve the observed hydration states. We thank the SHERLOC and Mars 2020 science and engineering teams for the data that enabled this study. This research was supported by funds to the SHERLOC instrument team and the NASA Mars 2020 mission. Y.P. and B.L.E. were supported by a Mars-2020 SHERLOC Co-Investigator grant to B.L.E. S.Si. acknowledges funding from the Swedish National Space Agency (contract 2021-00092 and 137/19). A.D.C. was supported by the Mars 2020 Returned Sample Science Participating Scientist Program (NASA award number 80NSSC20K0237). Support for R.C.W. and S.C. was provided by a SHERLOC Co-Investigator grant to R.C.W. and by NASA contract NNH13ZDA018O. Funding for R.S.J. was provided as an Advanced Curation project run by the NASA Astromaterials Acquisition and Curation Office, Johnson Space Center under the Jacobs, JETSII contract. MPZ was supported by Grant PID2022-140180OB-C21 funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. Research efforts carried out at the Jet Propulsion Laboratory, California Institute of Technology by K.H., S.Sh., K.U. were funded under a contract with the National Aeronautics and Space Administration (80NM0018D0004). L.M. was supported by a Texaco Postdoctoral prize fellowship awarded by the division of Geological and Planetary Sciences of Caltech.</p
Large-scale fire experiments in a cross-laminated timber compartment with an adjacent corridor – Partly and fully protected with a water sprinkler system
No full textTwo fire experiments have been conducted to study sprinkler system extinguishing performance in a compartment (13 m2) with an adjacent corridor (12 m2), both with exposed cross-laminated timber (CLT). Four nozzles were installed in the corridor and two in the compartment. In Experiment 1, the sprinkler system was fully functional and successfully controlled a concealed fire. In Experiment 2, nozzles in the compartment were disconnected, while the corridor nozzles were operative, giving flashover after 5 min with large flames emerging into the corridor, rapidly worsening evacuation conditions. Despite four activated nozzles in the corridor, the temperatures remained high, and flames spread through the corridor along the CLT ceiling and the upper parts of the wall, an area that was not effectively protected by the nozzles. After flashover, the compartment temperatures remained stable at ∼1000 °C until experiment termination at 96 min. This continued fire in the compartment can be explained by water from the corridor sprinklers not reaching this area, extensive radiative feedback by the CLT surfaces and delamination of CLT elements of the 20 mm layers. The charring rate was ≥1.1 mm/min for large parts of the exposed CLT wall and ceiling in the compartment during the fire. The experiments were financed by the owners of the building, the Student Welfare Organisation in Trondheim, Norway. The publishing of the results has been financed by the Fire Research and Innovation Centre (FRIC), which is funded by its partners, by the Research Council of Norway (program BRANNSIKKERHET, project number 294649) and the Gjensidige Foundation.</p
Nog!?
No full textThis magazine is produced as a provotype within the NOG!? project. We have used the magazine as a provotype within the NOG!? project to learn about how households in Sweden reflect on and could practice sufficiency.Enough!? Exploring sufficient and fair energy use through desig
A systematic evaluation of seven different scores representing the EAT–Lancet reference diet and mortality, stroke, and greenhouse gas emissions in three cohorts
No full textDifferent approaches have been used for translation of the EAT–Lancet reference diet into dietary scores that can be used to assess health and environmental impact. Our aim was to compare the different EAT–Lancet diet scores, and to estimate their associations with all-cause mortality, stroke incidence, and greenhouse gas emissions. We did a systematic review (PROSPERO, CRD42021286597) to identify different scores representing adherence to the EAT–Lancet reference diet. We then qualitatively compared the diet adherence scores, including their ability to group individuals according the EAT–Lancet reference diet recommendations, and quantitatively assessed the associations of the diet scores with health and environmental outcome data in three diverse cohorts: the Danish Diet, Cancer and Health Cohort (DCH; n=52 452), the Swedish Malmö Diet and Cancer Cohort (MDC; n=20 973), and the Mexican Teachers’ Cohort (MTC; n=30 151). The DCH and MTC used food frequency questionnaires and the MDC used a modified diet history method to assess dietary intake, which we used to compute EAT–Lancet diet scores and evaluate the associations of scores with hazard of all-cause mortality and stroke. In the MDC, dietary greenhouse gas emission values were summarised for every participant, which we used to predict greenhouse gas emissions associated with varying diet adherence scores on each scoring system. In our review, seven diet scores were identified (Knuppel et al, 2019; Trijsburg et al, 2020; Cacau et al, 2021; Hanley-Cook et al, 2021; Kesse-Guyot et al, 2021; Stubbendorff et al, 2022; and Colizzi et al, 2023). Two of the seven scores (Stubbendorff and Colizzi) were among the most consistent in grouping participants according to the EAT–Lancet reference diet recommendations across cohorts, and higher scores (greater diet adherence) were associated with decreased risk of mortality (in the DCH and MDC), decreased risk of incident stroke (in the DCH and MDC for the Stubbendorff score; and in the DCH for the Colizzi score), and decreased predicted greenhouse gas emissions in the MDC. We conclude that the seven different scores representing the EAT–Lancet reference diet had differences in construction, interpretation, and relation to disease and climate-related outcomes. Two scores generally performed well in our evaluation. Future studies should carefully consider which diet score to use and preferably use multiple scores to assess the robustness of estimations, given that public health and environmental policy rely on these estimates. DBI was supported by a research grant from the Independent Research Fund Denmark (grant number 1057-00016B). AS was supported by research grants from The Swedish Heart Lung Foundation (grant number 20200482), Crafoord Foundation (grant number 20210674), and Agenda 2030 Graduate School, Lund University. NGF is supported by the MRC Epidemiology Unit (grant number MC_UU_00006/3) and the National Institute for Health and Care Research (NIHR) Cambridge Biomedical Research Centre (grant number NIHR203312), and she is an NIHR Senior Investigator.</p