RISE – Research Institutes of Sweden
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3D-printing magnetic susceptor filament for induction welding of thermoplastic composite sandwich panels
No full textA magnetic susceptor in a printable filament form is developed for the induction welding of thermoplastic composites. The susceptor is based on Ni particles embedded in a poly-ether-imide matrix. It is extruded and spooled to form a filament which can then be 3D-printed. The susceptor produces heat by hysteresis losses due to the magnetic properties of the Ni particles. As opposed to other typical electrically conductive heating elements, no percolation threshold needs to be achieved to produce heat as the Ni particles individually heat up when exposed to the induction coil’s magnetic field. The heating efficiency of the susceptor filament and its deposition by the fused filament fabrication technique are demonstrated. The susceptor is used to assemble all thermoplastic composite sandwich panels. The sandwich samples are tested by the flatwise tensile test and a tensile strength of 4.6 MPa is obtained, which is equivalent to or higher than reported strengths for typical aerospace-grade sandwich panels. The printable susceptor opens the way to new induction welding or heating applications as it can be printed on a surface to produce a desired heating pattern.The authors acknowledge financial support from CREPEC (Research Center for High Performance Polymer and Composite Systems), NSERC (Natural Sciences and Engineering Research Council of Canada) (grant number ALLRP 556497-20), PRIMA Québec (Pôle de Recherche et d’Innovation en Matériaux Avancés) (grant number R20-13-004), the Canadian Space Agency (CSA), Ariane Group, NanoXplore inc, Mekanik and Dyze Design.</p
ATOS: An Open-Source Platform for Testing AI-Based Automated Vehicle Systems in Integrated Simulated and Physical Scenarios
No full textThe increasing complexity of automated and AI-based vehicle systems necessitates innovative testing methodologies to ensure safety, reliability, and performance in diverse and dynamic scenarios. This paper introduces AV Test Operating System (ATOS), an open-source platform that seamlessly integrates simulated and physical testing environments for Advanced Driver-Assistance Systems and Automated Driving systems. ATOS supports comprehensive scenario evaluations under varied conditions such as weather, traffic, and connectivity environments by automating and orchestrating tests involving multiple simultaneous virtual and physical objects. Key contributions of this work include: 1) The introduction and design of ATOS, an open-source platform for automating and orchestrating complex vehicle testing scenarios. 2) A method for evaluating the repeatability of automated test orchestration systems. 3) Data analysis of two scenarios where ATOS was used in real-life AV testing. Results demonstrate ATOS’s effectiveness in executing repeatable and reliable tests across diverse configurations, highlighting its utility for research institutions, vehicle manufacturers, and testing facilities. Using ATOS in repeated runs, the time delay when triggering dynamic events was within 1 millisecond with virtual objects and 7 milliseconds when using physical objects. The positional variation between runs using virtual and real-life objects amounted to 6 and 20 cm, respectively. Future enhancements will focus on integrating real-world data and expanding ATOS’s capabilities to support evolving vehicle testing needs, contributing to safer, more robust transportation systems.We thank Sweden’s Innovation Agency, Vinnova, for funding Grant Nos.2021-05042, 2022-01648, and 2023-01704 and 2023-03297 making the work described here possible. </p
Methodology for simulating ship damage stability and liquid cargo outflow for collision-damaged ships
No full textShip collisions and groundings are important due to their severe consequences, including exceedance of ultimate strength, loss of stability, and spillage of hazardous cargo and liquids. To mitigate these effects, cost-efficient simulation tools are needed for studying transient flooding and motions of damaged ships with different damage opening characteristics in a wave environment. The objective of this study is to present a validation of a liquid exchange model implemented in the time-domain-based dynamic ship stability simulation code SIMCAP, using experiments presented in the literature. The validated model was then applied in a parametric study of a fully loaded double-hull oil tanker damaged in the inner and outer hulls. Oil outflow, water inflow, and ship motions were analysed for different damage opening positions, shapes, and wave heights. The results showed that the damage location strongly affected the oil outflow. The oil spill rate increased with wave height but was relatively unaffected by heading and wave realization. In conclusion, SIMCAP was reasonably validated qualitatively and quantitatively and is suitable for investigating key physical mechanisms in parametric studies of damaged ships in waves.This study received financial support from the Swedish Transport Administration SHARC (Structural and Hydro mechanical Assessment of Risk in Collision and grounding) project (Grant No.: TRV 2019/42277). The FE analysis and SIMCAP simulations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at Chalmers Centre for Computational Science and Engineering (C3SE), partially funded by the Swedish Research Council through Grant No 2018–05973</p
Self-assembly induced patterning of biomimetic fatty acid monolayers reveals their protective role on hair
No full textBranched fatty acids, such as those found on the surface of hair and wool, have recently been shown to form novel 3D self-assembly curvature structures at the air–water interface—nanocaps. On the hair surface, the branched fatty acid 18-methyleicosanoic acid (18-MEA) is expressed together with shorter, unbranched, straight chain fatty acids to form a protective palisade layer. The biological function of the chain length differences was hitherto unknown. Using a combination of atomic force microscopy and Langmuir isotherms, a safe, versatile route for tuneable nanopatterning of solid surfaces is demonstrated, via fatty acid interfacial nanocap deposition from biomimetic mixtures. Further, it is shown that chain length dependence of the interaction with the branched chain is exquisitely sensitive, leading to profoundly different morphologies in the self-assembly structures. The vastly enhanced properties of the mixed films compared to the individual components alone reveals the biological origin of the hair surface composition. Swedish Research Council via grants VR 2013–04384, VR2021–04378.</p
Public sector open source software projects - How is development organized?
No full textContext: The adoption of Open Source Software (OSS) in Public Sector Organizations (PSOs) is on the rise, driven by benefits such as enhanced interoperability and transparency. However, PSOs encounter challenges stemming from limited technical capabilities and regulatory constraints in public procurement. Objective: This study, based on a registered report, explores the organizational aspects of development in public sector OSS projects, i.e., projects initiated, developed, and governed by PSOs. We conjecture that the development diverges significantly from the commonly adopted bazaar model, wherein development is carried out collaboratively within a broader community. Method: A purposefully sampled set of six public sector OSS projects was investigated using mixed-methods and compared with previously reported cases of bazaar OSS projects. Results: Among the cases, we note that most (80%) of development efforts typically involve a small group of developers (<15) and rely on formalised processes. Developers are commonly procured from national and local service suppliers. Projects are planned top-down by involved PSOs with funding and contributions to development enabled through centralized or decentralized sponsorship. Projects with a centralized sponsorship have one or a few main PSOs funding the major part of the development. Decentralized sponsorship implies multiple PSOs being mutually dependent on each other to pool the necessary resources for the development. All OSS are reported as being of high quality despite limited size and contributions from their communities. Conclusions: Findings suggest that public sector OSS projects deviate from the typical bazaar model, highlighting the need for tailored approaches to address challenges and solutions specific to their context. e.The research of G.Robles has been funded by the Spanish Ministry of Science, Innovation, and Universities under the Excellence Network AI4Software (Red2022-134647-T) and the Dependentium project (PID2022-139551NB-I00). The work of Francisco Servant was partially funded by the United States National Science Foundation (NSF) under award CCF-2046403, by Virginia Tech under a startup grant, by Universidad Rey Juan Carlos under the International Distinguished Researcher award C01INVESDIST, and by the Spanish Agencia Estatal de Investigación under award PID2022-142964OA-I00.</p
Thermochemical recycling of mixed plastic wastes through pyrolysis and steam cracking – Assessment of centralized vs. Decentralized approaches
No full textThermochemical recycling of medical plastic waste (MPW) was evaluated experimentally and through development of mass & energy balances. Fluidized bed (FB) steam cracking of MPW at a centralized petrochemical site was compared to thermal and catalytic pyrolysis of MPW to intermediate WAX (thermal) and POil (catalytic) feedstocks at a decentralized site, followed by FB steam cracking of WAX and POil at a centralized petrochemical site. Pyrolysis and FB steam cracking experiments were performed in lab-scale reactors. Steam cracking yields of primary products (light olefins, C2-3 alkynes, BTXs) were highest for MPW, followed by WAX, and POil feedstocks. Higher steam cracking temperature increased the primary product yields for the MPW feedstock but showed a less significant effect in WAX and POil cases. For all cases, higher cracking temperature increased chain scission and hydrogen abstraction, resulting in rising yields of ethylene, methane, and hydrogen, and lower yields of longer chain aliphatic hydrocarbons. Material, carbon, and energy balances, developed from experimental results, showed that excess heat from incineration of pyrolysis and steam cracking byproducts can meet the energy demands of the pyrolysis and steam cracking processes. The balances also showed that direct FB steam cracking of MPW can achieve high product yields and high rates of fossil carbon recycling. However, steam cracking of WAX feedstock, the product of pyrolysis pre-treatment, can achieve moderate product yields and fossil carbon recycling while realizing several practical advantages: easier transport, reduced need for feedstock preparation, and removal of ash and heteroatoms for improved steam cracker operability. The work was conducted within the framework Climate-leading Process Industry funded by Vinnova (2022-01445), Västra Götalandsregionen and the Chemicals and Material Cluster of Western Sweden.</p
Hållbara markanvisningar
No full textThe project Sustainable Land Allocation – More Sustainable Construction through Improved Land Allocation Processes was led by RISE Research Institutes of Sweden in collaboration with municipalities, developers, and academic partners. It aimed to support municipalities in setting more consistent, transparent, and effective requirements in land allocation processes, in order to strengthen sustainability outcomes in urban development. The main result is a practical guidance document that helps municipalities formulate and follow up on requirements and criteria related to economic feasibility, social sustainability, and environmental and climate impact. The guidance was developed iteratively and tested in real-life municipal processes by over 20 municipalities. The project identified key challenges such as legal uncertainty around technical requirements, the complexity of addressing social values, and the need for adaptable, place-specific criteria. It also fostered collaboration across sectors and laid the foundation for a long-term structure for continued use and development of the guidance. The guidance is publicly available and intended as a flexible toolbox that municipalities can tailor to their local context and policy goals.Vinnovas (Verket för innovationssystem) utlysning ”Bygg för framtiden! Innovation för en hållbar bygg-och anläggningssektor” under perioden 2023–2025.</p
Users’ perspectives of bi-directional charging in public environments
No full textVehicle users’ adoption of vehicle-to-grid (V2G) is essential for the system's ability to perform V2G grid services. What charging preferences, needs and routines do EV users have and why? What future expectations do EV users have for bi-directional charging? To answer these research questions, a multimethod study is performed (interviews and survey). The following themes were identified as critical for the acceptance of V2G technology in the everyday life of the interviewees: Convenient and resilient home, minimum range for emergencies, fear of battery degradation, trust in system providers, economic and social incentives, user preferences and need for control. Linear regression models identified associations between sociodemographic characteristics and evaluations of V2G in terms of sustainability and efficiency. The interest in creating resilient homes among certain consumers and EV drivers suggests a demand for services that integrate technologies for home energy efficiency and V2G.We want to acknowledge the Swedish Energy Agency for funding the project and all project partners from the PEPP project: Lindholmen Science Park; Johanneberg Science Park; Volvo Cars; Chalmers; RISE Research Institutes of Sweden; CTEK Sweden; Easypark; Göteborgs stads Parkering; Mölndals Parkering; Göteborg Energi Nät; Mölndal Energi; Business Region Göteborg; MölnDala Fastighets AB.</p
Swedish EV users’ routines and behaviors without home charging availability
No full textThis paper presents the results of an online survey addressed to current EV users in Sweden. The aim of the paper is to improve knowledge of a previously overlooked group in the electric vehicle adoption literature – households that lack the possibility to install their own home charger. Of specific interest in this investigation is revealing the charging needs, behaviors, and perceptions of this group. The results of the study are based on an online survey with 250 EV users, the majority of whom were in Gothenburg. EV users were divided into two groups: a group with home charging availability and a group without home charging availability. Linear regression models comparing the two groups showed that users without home charging availability perceive public charging as less convenient, further from their homes, and they have a lower perception of freedom to charge.We thank the Swedish Innovation Agency Vinnova for funding the project and participating project partners for assisting in the survey data gathering process.</p
A bi-level optimization model for project scheduling and traffic flow routing in railway networks
No full textLong-term tactical infrastructure planning for a transportation network consists of deciding on renewals and major maintenance works. Such projects constitute large budget volumes and will impair the available traffic capacity during their execution, especially for railway systems. Quantitative methods that schedule and coordinate infrastructure projects together with traffic flow adaptations is however largely lacking today. This paper addresses the joint planning of temporary capacity restrictions and traffic flow adaptions during track work closures, by proposing a bi-level optimization model which separates the problem into project scheduling (upper level) and traffic assignment (lower level). The latter model uses a novel traffic flow formulation for routing volumes of trains through the transportation network under the capacity restrictions given by the project scheduling. An aggregated network is used together with time discretized into uniform periods, which makes it possible to treat large national planning problems with a planning horizon of up to a year and a period length of a couple hours. The computational properties are evaluated, both for the individual models, and for their joint usage. Furthermore, results from applying the models on two case studies, concerning Northern and South-Western Sweden, are presented. The main conclusion is that the model formulations are capable of solving realistic planning cases and to provide support for capacity planners at an infrastructure manager, even for a large national railway. The results show that a good overview over the collective traffic impact is obtained, but also that details of particular traffic relations or capacity usage over individual network links and their variation over time can be studied. One major deficiency has been identified in the flow-based traffic assignment model, which can lead to incoherent train flows over long traveling distances and many time periods. This research has been funded by Trafikverket, Sweden, via the research program KAJT (Capacity in the Railway Traffic System), and the grant TRV 2021/119827 (work order 179336100).</p