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- An approximation algorithm for Demand Strip Packing with moldable jobs(2026) Bergquist, WilliamIn Strip Packing (SP), the aim is to place a set of rectangles, often called jobs, inside a strip with a bounded width D and infinite height with no overlaps whilst minimizing the height needed to fit all jobs. In Demand Strip Packing (DSP), we relax this problem by allowing jobs to be sliced vertically. DSP can more accurately model certain problems such as electricity allocation whilst also allowing for better optimal solutions than SP. In some applications, it may be the case that a specific job could be scheduled in multiple ways. We say that a job is moldable if there are multiple options for its processing time and energy demand. The goal of the problem now becomes to find both the optimal way of scheduling the jobs but also which processing configuration each job should use. Both SP and DSP are NP-hard problems and thus, obtaining optimal solutions to instances of these problems is not computationally feasible. Instead, research is focused on developing approximation algorithms which can find a solution that is “good enough” whilst running in polynomial time. In this thesis, we present an approximation algorithm for DSP with moldable jobs. The algorithm runs in polynomial time with respect to the number of jobs and returns a packing whose peak demand is at most (3/2 + ε) times the optimal peak demand for some ε > 0. This result is very close to the best possible approximation ratio, proven to be 3/2 for DSP. The algorithm as constructed, as well as the approximation ratio, is dependent on an assumption that will be a focus of further study. Key to the design of this algorithm is our approach of transforming an optimal packing in a particular way such that a strong structural result holds. The algorithm then makes heavy use of guessing and linear programming to find a feasible solution within the approximation ratio.
- Regulation-Directed Cybersecurity Best Practices for Operational Technology Environments(2026) KAICHETTY, PRAHITHA; VUPPALA, SREELEKHAOperational Technology (OT) systems refer to hardware and software used to monitor and control physical processes, devices, and infrastructure in industrial environments. These systems are typically designed for long operational lifecycles and are expected to function reliably over extended periods. In recent years, industrial sectors have increasingly integrated OT systems with Information Technology (IT) networks to enable digital transformation, improve data-driven decision-making, and support remote monitoring and control, thereby enhancing operational efficiency and connectivity. However, this integration also introduces significant cybersecurity risks. The incorporation of legacy OT systems into modern and continuously evolving IT environments makes them more vulnerable to cyberattacks and easier to exploit. Cyber incidents targeting OT systems can result in severe consequences, including physical damage to equipment, production disruptions, financial losses, safety risks to personnel, and loss of operational control. Consequently, OT environments have emerged as critical targets for malicious actors. To address the growing cybersecurity threat landscape, the European Union has introduced the Network and Information Security Directive 2 (NIS2) Directive, which establishes standardized cybersecurity requirements for essential and important entities, including those in the manufacturing sector. Prior to the introduction of NIS2, the National Institute of Standards and Technology (NIST) cybersecurity framework has been widely adopted across industries as a best-practice guideline for managing cybersecurity risks. Most companies are required to meet the NIS2 requirements, however redesigning the security infrastructure from scratch is an expensive and complicated process. One possible approach to address this issue is to map NIS2 requirements to existing cybersecurity frameworks. In this thesis, NIST standards are mapped to the NIS2 Directive to identify compliance gaps and evaluate cybersecurity alignment within IT and OT environments. The associated risks in OT components are analyzed through the development of a Failure Modes and Effects Analysis (FMEA) table. Additionally, an OT and IT component checklist is created to ensure the adequacy mitigation and redundancy measures across systems. This approach helps identify existing gaps, thereby improving overall security and strengthening compliance. Furthermore, it enables organizations to proactively address vulnerabilities and adapt to evolving cybersecurity threats.
- Comparative Analysis of the Dielectric Performance of Insulating Liquids Aged Under Different Conditions(2026) Svalander, Moses; Dahlman Zakrisson, JoelThis thesis investigates the dielectric performance of transformer oils used as high voltage insulation media in membrane-sealed and fully enclosed transformers and compares the impact of the sealing methods. Oil samples were collected from real transformer units, which were operating under different conditions over several years and the insulating oils in them were exposed to combined electrical-thermal stresses of different duration and intensity. It was anticipated that the intake of air through the sealings of the transformer tanks might initiate chemical reactions under such stresses thus causing accelerated ageing of the insulation. To examine this hypothesis, dielectric measurements and breakdown tests were conducted according to the respective standards. The former included measurements of complex capacitances, loss factor and oil resistivity whereas the latter provided the maximum electric field strength the oil could withstand. The obtained results indicate a rapid initial degradation in some of the measured parameters, while the evidence for storagetime- dependent degradation remains inconclusive. Under the applied test conditions, the oil samples taken from fully enclosed transformer tank showed a slightly better performance than those from membrane-sealed tank. To explicate this finding, an attempt to correlate the measured results with the histories of the respective transformer units is undertaken. Ageing factors affecting performance of the insulating oils, including chemical degradation under electro-thermal stresses and possible contaminations, are discussed based on the performed literature study.
- KULTURVERKSTAN I GAMLESTADEN(2026) Friström, Carl