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    Multi-Layered In-Vehicle Communication Architectures
    (2026) El Hage, Ali; Qian, Mattias
    Modern bus platforms contain an increasing number of electronic control units (ECUs) distributed over long physical distances. This creates challenges for the in-vehicle communication architecture, since long cable routes, increasing traffic demands, and stricter timing requirements may reduce communication robustness and increase end-to-end delay. Controller Area Network (CAN) is widely used in vehicle systems due to its robustness, simplicity, and established industrial use. However, in long vehicle platforms, CAN-based communication may approach practical limitations related to cable length, signal integrity, and transmission delay. This thesis investigates how a multi-layered in-vehicle communication architecture can be modeled and optimized by combining different communication technologies in a common bus architecture. The considered technologies include CAN, Ethernet, and AUTBUS. The objective is to determine where different technologies should be used and where converters should be placed in order to balance total system cost and communication delay. A mixed-integer linear optimization model is developed to assign communication technologies to discretized bus segments and to determine the required gateway placements. The model includes cable costs, gateway costs, gateway delays, transmission delays, propagation delays, ECU interface constraints, and a maximum consecutive CAN length constraint. Since cost and delay are conflicting objectives, an epsilon-constraint method is used to generate Pareto-optimal architecture alternatives. A secondary fine-tuning model is also introduced to refine boundary positions after the discrete topology has been selected. In addition to the mathematical model, physical gateway latency measurements are performed using a CANcase, CANalyzer, and CAPL scripts. The measurements show that gateway latency is not constant, but varies depending on transmission interval and network traffic. The measured latency is therefore used as a representative modelling parameter rather than an exact deterministic value. The results show that optimization framework can identify meaningful trade-offs between cost and delay in a long bus communication architecture. The Pareto front provides several feasible design alternatives, ranging from low-cost solutions with higher delay to more expensive architectures with lower delay. The fine-tuning step further reduces cost for selected Pareto points, especially in the higher-cost region of the frontier. Overall, the thesis demonstrates that mixed-technology communication architectures can provide a structured approach for improving timing performance in long vehicle platforms, provided that gateway behavior, protocol constraints, and implementation complexity are carefully considered.
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    Chemical Looping Gasification of Biomass in a 20 kWth pilot plant
    (2026) Landgren, Lina
    The increasing demand for carbon neutral fuels to reduce carbon emissions highlights the need for novel, efficient, and scalable processes for converting low grade biomass into bio fuels. This study investigates the influence of operating conditions on biomass gasification for methanol production using Chemical Looping Gasification (CLG). Experiments were conducted in a 20 kWth pilot plant using ilmenite as the oxygen carrier. The effects of air supply, operating temperature, and gasifying agent composition on process performance were investigated using two different biomass fuels: Waste Wood type B (WWB) and Microalgae (MA). An increased air-to-fuel ratio resulted in a higher degree of combustion, which reduced the concentrations of syngas components (CO and H2) and consequently decreased syn gas production. A decrease in temperature reduced the fuel conversion rate, resulting in a greater fraction of carbon being converted in the Air Reactor rather than the Fuel Reactor. Comparing the achieved gas equilibrium and the theoretical according to the water gas shift equilibrium indicates a temperature dependent catalytic effect the final gas composition. An increased fraction of CO2 in the gasifying agent did not significantly affect fuel reactivity or conversion. However, it increased the amount of carbon introduced into the system and consequently increased the fractions of CO and CO2 in the product gas. Comparison of the two biomass fuels indicates that WWB provides more stable operation and produces lower concentrations of pollutants in the form of NOx than MA. WWB therefore appears to be the more favorable fuel under the investigated conditions.
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    Equilibrium Modeling of a MOX-Iron Corrosion System
    (2026) Backman, Majken
    Anoxic iron corrosion is expected to play a key role in limiting radionuclide release from spent nuclear fuel following a canister breach, making it important to under stand and model the interaction between nuclear fuel and water with increased iron levels. This thesis develops an equilibrium model of the nuclear fuel-water system as a step towards a more predictive model of MOX fuel corrosion under repository con ditions. The experimental system is defined by two main processes: the corrosion of iron and the addition of the MOX pellet containing UO2, PuO2 and trace amounts of AmO2. The developed model, based on this system, focuses on iron corrosion, controlling uranium solubility and potential precipitation of secondary phases. To decide the optimal iron corrosion configuration, equilibration with an unconstrained or a constrained amount of available metallic iron was studied. The MOX pellet was modeled as a solid solution. Different phases containing uranium and ameri cium were equilibrated with the solution to bring their dissolved molalities down to physically reasonable levels; uraninite and Am(OH)3(am) were found to work best. Precipitation of secondary phases was tested by placing them in equilibrium with the solution, first one by one, and then in pairs of two. The simulation showed that the constrained iron model matched the experiment more closely than the uncon strained model, based on pH, pE, and the molalities of Fe(II) and Fe(III). Addition of the MOX pellet further increased the reducing conditions of the system. As the secondary phases were tested, all were thermodynamically possible, but no clear cor relations were found to decide whether they were present or not. The lack of kinetic parameters limited the model, as it was developed as an equilibrium model and thus shows the system’s conditions at a specific point in time rather than its continuous development. The results of the simulation showed reasonable agreement with the experimental system it was based on, though the model’s consistently more reducing conditions suggest that further development would be needed for closer replication or the experimental results.
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    Emergency communication onboard uncrewed ferries - Exploring the Requirements and Challenges of a Passenger Information and Communication System for Emergency Situations on Autonomous Uncrewed Ferries
    (2026) Agneskans Falk, Philip; Toftefors, Anya
    The maritime sector, like many other industries, is seeing a development in automation; with this, RISE and Trafikverket have started the EMERGE project to explore what a transition to uncrewed ferries would entail. This thesis aims to explore the requirements and challenges of a passenger information and communication system for autonomous uncrewed ferries during emergencies, focusing on man overboard (MOB), fire and evacuation scenarios. First, a literature review was conducted to establish the perceived safety today, relevant design theories, existing solutions, and common procedures for emergency scenarios. This was followed by user studies that explored passengers’ expectations for communication and action from crew and ship if an emergency were to occur, as well as their perceptions of autonomous and uncrewed ferries. The findings indicate that passengers require clear, timely, and trustworthy communication during emergencies. Information should be provided through multiple communication channels, combining auditory and visual cues to improve accessibility and situational awareness. Passengers also expressed a strong preference for human communication during emergencies, highlighting the importance of maintaining a connection to remote operators even in highly automated systems. Furthermore, the findings suggest that passengers are generally willing to assist during emergencies if provided with clear instructions, although emergency procedures should be designed around simple and familiar tasks that do not require specialised knowledge. The absence of onboard personnel also increases the importance of intuitive interfaces that inspire trust, reduce uncertainty, and support informed decision-making under stress. With these findings, a list of requirements was created to guide the ideation and evaluation process. Using design methodologies such as brainwriting, the ideation process yielded many different ideas, which were further developed and assessed through a combination of design methods, workshops, user tests, and expert interviews. This culminated in a final concept consisting of several complementary solutions that together meet the requirements to a level sufficient for use without a crew present, though it requires further development and evaluation before being ready for real-world testing.