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Senast publicerade

Studio i mekanik och hållfasthetslära: Praktisk applicering av teoretiska modeller inom balkböjning och hållfasthetslära
(2026) Andersson, Fanny; Andersson, Nellie; Persson, Sebastian; Pramås, David
Studio i mekanik och hållfasthetslära har varit ett återkommande kandidatarbete på institutionen för Mekanik och maritima vetenskapen sedan 2013. Det har under åren tagit många former där fokus har skiftat mellan att rusta upp den nuvarande samlingen med experiment och att skapa nya experiment. Denna rapport beskriver arbetsgången för framtagningen av en ram med infästning- ar där balkar kan lastas och grundläggande balkteori inom hållfasthetslära skall visas. Denna rigg är designad för enkel användning och implementering i grundkur- ser inom hållfasthetslära på Chalmers Tekniska Högskola. Till denna rigg hör ett kodskelett för beräkning av utböjning på dessa balkar enligt grunderna som intro- duceras i kursen Hållfasthetslära (MTM026) på programmet för Maskinteknik och ett laborations-PM. I detta PM finns genomgångar av hur riggen fungerar och en handfull uppgifter/ex- empel ligger med som underlag för en praktisk laboration. I dagsläget finns ingen praktisk laboration i Hållfasthetslära (MTM026), utan de laborationer som finns bygger på att använda programvaror för att illustrera vissa fenomen inom balklära. Detta ville gruppen ändra på och därför ta fram en laboration som skall integreras i denna kurs, där gapet mellan teori och praktik förhoppningsvis minskas. Efter all design, allt byggande och tillhörande testning lämnar gruppen efter sig en rigg där de vanligaste grundfallen inom balklära kan byggas och experimenteras på. Ett komplett ritningspaket från detta arbete finns även för eventuella reparationer eller reproduktion av riggen i framtiden. Gruppen lämnar även efter sig en diskussion med framtida förbättringspotential, dels lärdomar av saker som genomförts, men även saker som inte hunnits med under arbetets gång. Detta hoppas gruppen kan motivera kommande år av Studio i me- kanik och hållfasthetslära att fortsätta utvecklingen av detta projekt och göra det mer applicerbart för att till slut bli en komplett laboration som kan bli en del av kursplanen för Hållfasthetslära (MTM026).
Using LoRA to Improve Retrieval in Structured Document Collections
(2026) Wassenius, Marcus; Junayd, Kader
This thesis explores different roles for Low-Rank Adaptation (LoRA) in a question answering (QA) system over structured document collections, and aims to shed light on benefits and limitations as well as rank requirement interactions with dataset size and confusability. Three roles are investigated on synthetic document collections mimicking company data. First, LoRA as parametric memory to internalize new knowledge directly into the model weights; second, LoRA as a tool for embedding adaptation in a retrieval-augmented generation (RAG) system to improve retrieval performance by improving the vector representations of chunks; third, LoRA as a tool for context routing in a RAG system to improve retrieval by narrowing the search space. The findings suggest that LoRA is a flexible tool that can improve QA performance in all three roles, but that each role comes with its own characteristics and trade-offs between for example performance, flexibility, and robustness. In the specific settings tested, parametric memory is shown to be effective and highly rank sensitive; embedding adaptation is shown to give robust retrieval and generation improvements already at low ranks with gradual benefits of increased rank; context routing is shown to give large retrieval benefits at low rank requirements but introduces certain brittleness in both the retrieval and generation step.
Islanded Operation of Wind Turbine with Solar Power and Battery Storage - A Power-Balance-Oriented Energy Management Approach
(2026) Xu, Tianxing; Zhang, Yichi
This thesis studies the monitoring and control of an islanded hybrid power system composed of a wind turbine, photovoltaic generation, a battery energy storage system, and local load demand. The motivation of the study is that when the system operates without the continuous support of the external power grid, it needs to coordinate local power generation and energy storage. Therefore, the research focuses on the analysis of active power balance, battery dispatch, wind-power curtailment, load shedding and wind turbine response under islanded operating conditions. A layered modelling strategy is used in MATLAB/Simulink. The inherited windturbine model is kept as the wind-side technical basis, and the main work of this thesis is to build and connect an Energy Management System (EMS) around it. The EMS takes the realised wind-turbine output, an equivalent AC-side photovoltaic active-power contribution, load demand, and battery state of charge as inputs. It then calculates the battery-power reference, the constrained battery response, the residual mismatch quantities, the wind-curtailment request, and the load-shedding request. In this work, the available wind-power estimate and the realised simulated wind-turbine output are not treated as the same signal. The available wind-power signal is used as a wind-side availability reference, while the realised wind-turbine output is the simulated power after the turbine dynamics and, when it is active, the wind-spill and blade-pitch action. An important implementation point is that the EMS curtailment request is sent to the inherited wind-spill input as a spilling-power command. Therefore, curtailment is represented through the turbine-side control path, rather than by directly subtracting power from the wind-power signal. In the short-term integrated simulation, the EMS response is analysed together with the simulated blade-pitch response, the wind-spill command, and the realised wind-turbine power. The results show a change from an initial deficit condition to a surplus condition. After this change, the battery charging becomes constrained, residual surplus is formed, the wind-spill request is activated, and the realised simulated wind-turbine output is reduced. A complementary long-term EMS/BESS simulation is performed over an 1800 s horizon using prescribed wind, PV, and load input profiles. The battery-power reference, constrained battery power, SOC evolution, original and residual mismatch quantities, and corrective-action requests are analysed as simulation outputs of the developed supervisory controller. The long-term results show that the battery first absorbs renewable surplus within its implemented charging and SOC constraints, while remaining residual surplus is assigned to wind-power curtailment. An additional deficit-dominated EMS-level case is included to verify the load-shedding branch of the supervisory controller. In this case, an imposed high-load interval produces a power deficit that exceeds the allowable battery discharge response. The battery first supplies power within its implemented limit, after which the remaining residual deficit is converted into a load-shedding request. This case complements the surplus-dominated long-term case and confirms the intended priority order of the EMS under both surplus and deficit conditions. This thesis shows that the developed supervisory structure provides a useful simulation framework for the operation of an islanded wind-solar-battery system. The study clarifies the difference between prescribed operating inputs, inherited windmodel quantities, and simulated EMS/BESS outputs; it also gives a basis for future work on more detailed converter-level implementation, improved battery modelling, and wider islanded microgrid studies.
Designing a Trangia Coffee Brewer
(2026) Östman, Rasmus; Lindh, Agust
This master’s thesis explores the development of a specialised coffee brewing accessory tailored for Trangia AB, a leading Swedish manufacturer of outdoor cooking stoves. The aim of the project was to create a simple, reliable brewing solution that enriches the outdoor experience, uniting contemporary coffee habits with Trangia’s core values of sustainability, simplicity, and backwards compatibility. Through an exploratory design process involving benchmarking, brand analysis, and qualitative user research, the needs of the primary target user groups were identified. By utilising iterative concept generation methods such as brain drawing, rapid physical prototyping, and evaluation matrices, multiple brewing mechanisms were explored. The final selected concept is the ”Auto Drip”, an innovative solution that brings drip coffee to the outdoor segment. Powered by the stove’s heat, the device utilises the principles of a percolator, collecting steam in a pump base to push boiling water through a pipe and into a filter holder. This design provides a highly desirable ”set it and forget it” experience while delivering consistent drip coffee in the field. Prioritising packability and seamless integration, the lightweight metal components pack flat within Trangia’s existing 25 and 27 stove systems. Ultimately, the project resulted in a robust, modular accessory that maintains a visual language that respects Trangia’s heritage while meeting modern campers’ expectations for reliable outdoor functionality
Global Sensitivity Analysis of a Digital-Twin for Battery Electric Vehicles -Data Pipeline Development for Large-scale Simulations
(2026) Claesson, Hugo; Svanbro, Cassandra
Modeling is a central tool in the development of battery electric vehicles, particularly in applications of validation and system optimization. This thesis aims to assist the development of simulation platforms through a large-scale global sensitivity analysis of a digital twin representing a heavy duty battery electric vehicle, using energy consumption as the primary output. The Elementary Effects Test was implemented to screen the model input space, after which a Sobol’ sensitivity analysis was conducted on the most influential input parameters. The sensitivities were further explored through derivative-based measures, linear regression and Monte Carlo filtering. The results consistently identified the gross combination weight as the overwhelmingly most influential parameter. The Sobol’ analysis further indicated that, depending on the drive cycle, this parameter accounted for between 25% and 77% of the total output variance. In addition the initial temperature, the aerodynamic drag area and the rolling resistance coefficient were concluded as influential input parameters but not in the same magnitude. The relative ranking of parameter importance was found to vary with the drive cycle used for the simulations. The linearity of the relation between input parameter and output was also investigated. Gross combination weight, rolling resistance coefficient and the aerodynamic drag area were found to have mostly linear effects on the output, thus suggesting that these relationships can be represented by simplified models in future work.