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Enhancing Operational Excellence A Systematic Analysis of Material Flow in Battery Gigafactory Quality Control
(2024) Abrahamsson, Sofia; Dang, Viviane; Chalmers tekniska högskola / Institutionen för teknikens ekonomi och organisation; Chalmers University of Technology / Department of Technology Management and Economics; Sjöberger, Carl; Sjöberger, Carl
As nations strive to reduce their dependence on fossil fuels, the need for high-performance, durable batteries has increased drastically. One of the areas where this is especially important is the automotive industry, and one of the companies that have taken a part of this is Volvo Cars. They have adopted a new electrification strategy, with a decision to sell only electric cars from the year 2030. To meet the increased demand for batteries and ensure that the batteries are tailored for their cars, Volvo has formed a joint venture with the battery manufacturer Northvolt, called NOVO Energy. Spring of 2024, NOVO is in the design phase for a new battery factory that is being built next to Volvo Cars’ car factory in Gothenburg. They need to make sure that the material flows within the factory are efficient before the factory is finished, and one of the parts of the factory where this is essential is the quality lab. The purpose of this project was to identify bottlenecks in the material flow of samples within NOVO Energy's quality lab and propose solutions for how they can be minimized. This was done by analyzing data from Northvolt’s factory in Skellefteå, and completing it with updated requirements for NOVO. There were several bottlenecks that were discovered and the biggest three were the instruments CMM, Karl Fischer titration and VMZ. The root causes for them were investigated by the Five Whys and Fishbone Diagram methods, and the analysis revealed that they existed due to the sampling frequency being too high, the instruments being too slow and there being too few instruments of each type in the lab. Several ways to reduce the three bottlenecks were proposed. These were based on the priority list - in line tools, new technology, more instruments. The CMM could not be moved to in line or exchanged for a faster technology, so the solution was to invest in more instruments and decrease the sampling frequency. The Karl Fischer titration could not be turned to an in line tool either, but it could be replaced by a faster instrument called NIR. The VMZ could be moved in line and be supplemented with a few instruments in the lab for validation purposes.
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End-of-Life Management for Digital Battery Passports in Electric Vehicles
(2025) Cota, Eleonora; Ingman, Molly; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Despeisse, Mélanie; Persson, Hanna
The use of batteries increases every year, and it is more important now than ever to transition into a sustainable way of handling them in the right way. This requires traceability along the whole battery value chain, including information from mining raw materials until the battery is recycled. The EU has implemented the battery regulation, stating that a digital battery passport (DBP) will be required from February 2027. The DBP enables traceability of the battery and facilitates the recycling process. However, the DBP system is not yet finalized, and research shows that there is a gap in guidelines for how it should be managed during its end-of-life (EoL). Therefore, this project aims to determine how to manage DBP for Li-ion electric vehicle batteries (EVB) in the EoL phase to enhance traceability, enable a circular economy and enforce a sustainable transition. This project investigates the complete battery value chain to understand the EoL. Through a literature review and interviews, this thesis dives deeper into the management of batteries, appropriate solutions of ending its corresponding DBP and loopholes that may occur. The results show that the responsible economic operator (REO) creating the DBP is the owner and the responsible actor during its whole existence and is the only one that has the right to end it. This means further that independent operators never will have REO responsibilities, on the other hand, they are obliged to update DBP when needed for the battery. A DBP can only end after its product has been recycled and when this occurs, the recycling station will automatically inform the REO to end the DBP. A two-step verification process controls each individual product and informs its status to the corresponding REO and reduces the risk that information for some products would not be documented. For the recyclers who receive information about all products, this thesis presents a solution for module identification (MID), enabling modules to carry information, since the DBP only follows the complete battery pack. With the two-step verification process, the proposal with MID and keeping the responsibility by the REO, the loopholes regarding lack of information on products within the system can be significantly reduced. In conclusion, this thesis provides guidance on how to manage the DBP in the EoL phase based on currently available information and decisions on the topic.
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Optimization of coupling interfaces between nanophotonics waveguides and optical fibers
(2025) Haidar Hussein, Ali; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap (MC2); Chalmers University of Technology / Department of Microtechnology and Nanoscience (MC2); Torres Company, Victor; Gao, Yan; Shekhawat, Vijay
The integration of photonic components into compact and efficient circuits necessitates effective coupling mechanisms between optical fibers and on-chip waveguides. This thesis focuses on optimizing the coupling efficiency between silicon nitride (Si3N4) waveguides and optical fibers using linear adiabatic edge tapers. Addressing the significant challenge of minimizing coupling losses, the study explores the interplay between taper geometry, cladding thickness, taper and physical gaps for both standard single-mode fibers (SMFs) and lensed fibers. Utilizing both advanced simulation tools—Finite-Difference Eigenmode (FDE), Eigenmode Expansion (EME), and Finite-Difference Time-Domain (FDTD) methods—and experimental validation, the research systematically investigates the parameters influencing coupling efficiency. FDE simulations provide initial insights into mode mismatch losses due to mode field diameter (MFD) disparities. EME simulations are employed to optimize taper lengths, ensuring adiabatic mode transformation with minimal loss. FDTD simulations offer a comprehensive 3D analysis, capturing detailed electromagnetic interactions at the coupling interface. Experimental prototypes were fabricated and tested to validate the simulation results and assess practical fabrication considerations. The results demonstrate that optimal coupling for SMFs is achieved with a taper length of approximately 1mm, a facet width between 100nm and 150nm (with 125nm yielding the lowest loss), and a cladding thickness of 6µm, resulting in coupling losses around 0.75dB. For lensed fibers, both simulations and experiments indicate that a taper length of 50µm, a facet width between 230nm and 290nm (with 290nm yielding the losses in the simulations around 0.37 dB per facet and an experimental loss of around 1.1dB per facet which is possible to reduce even further), and a cladding thickness of 3µm yield optimal coupling efficiency. The slight discrepancies between simulated and experimental results are attributed to fabrication imperfections, including sidewall roughness and taper dimension deviations. The study underscores the critical impact of physical gaps and beam divergence on coupling efficiency, emphasizing the necessity of precise alignment and minimal separation in practical applications. Experimental results confirm that minimizing the taper and physical gaps is essential for lensed fiber coupling, with coupling losses yielding a constant value for gaps that are larger than 0.5µm. The thesis identifies limitations related to fabrication imperfections and suggests avenues for future research, including broadband performance analysis and the incorporation of fabrication-induced variations into simulations. The findings offer valuable design considerations for enhancing fiber-to-chip coupling in Si3N4 phov tonic integrated circuits, contributing to the advancement of efficient and scalable optical communication technologies.
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ADHD, Mental Health and Smart Devices - Exploring Preferences and Perceptions of Smart Watches and Devices and their Potential Role in Supporting Adults with ADHD
(2024) Salomonsson Stridsberg, Evelina; Chalmers tekniska högskola / Institutionen för data och informationsteknik; Chalmers University of Technology / Department of Computer Science and Engineering; Fjeld, Morten; Mylonopoulou, Vasiliki
This thesis explores the potential of wearable technology, specifically smartwatches, to assist individuals with Attention-Deficit/Hyperactivity Disorder (ADHD) in managing daily challenges. ADHD is characterised by inattention, hyperactivity and impulsivity, which can significantly affect executive functioning and overall well-being. The study investigated how individuals with ADHD currently use wearables and other technologies, their preferences, challenges and perceived benefits. It also explored how smartwatches can be tailored to provide support and how these devices can integrate the strategies that individuals with ADHD use to address their everyday challenges. It concludes that smartwatches can be tailored to address these challenges through features like customisable notifications, alarms, timers and reminders that align with the individuals routines, as well as quick note-taking through voice recording. Additionally, it emphasises the importance of providing education, trial opportunities and personalised setup assistance to enhance the adaption and effective use of wearable technology. The findings highlight the need for further research and integration of these tools within healthcare systems or educational institutions to provide additional support for people with ADHD in their daily lives.
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Evaluating the Strategic Value of Maintenance in Swedish Manufacturing – A Survey Study
(2024) Khatri, Sagar; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Ylipää, Torbjörn; Ylipää, Torbjörn
This Master's thesis examines the strategic importance of maintenance in the manufacturing industry, focusing on how annual investments in maintenance influence operational efficiency and financial performance. The research utilizes a mixed-methods approach, combining literature review and surveys conducted across various Swedish manufacturing firms. It assesses the impact of maintenance strategies on annual investments and the required skills for workers, emphasizing the increasing need for continuous training due to rising labor costs associated with skilled personnel. Key findings indicate that firms adopting advanced maintenance strategies, which integrate predictive and proactive techniques supported by modern technologies, significantly reduce operational costs and minimize downtime. These strategies not only enhance the sustainability of manufacturing processes but also address environmental challenges, making a strong case for their broader adoption. However, the study identifies challenges such as the high initial costs of technology and the continuous need for upskilling workers to keep pace with technological advancements. The thesis supports viewing maintenance as a strategic investment within the manufacturing sector, crucial for improving productivity and achieving a competitive advantage while promoting sustainable practices.