https://www.um.edu.mt/library/oar/handle/123456789/9973 2026-06-18T12:50:33Z https://www.um.edu.mt/library/oar/handle/123456789/147102 Title: The PQ8 architecture : deploying picosatellite constellations from a single launch Abstract: Over the past decade, demand for nano- and pico-class satellites has surged, driving up costs and competition for launch opportunities. CubeSat launches, once easily accessible, have become prohibitively expensive for small institutions, especially when considering constellation deployment. Although the PocketQube standard offers a lower cost alternative, its adoption has been limited and its cost benefits modest, primarily due to launch integration limitations, debris mitigation and trackability concerns. To address these challenges, this work proposes the PQ8 Architecture: a novel deployment model for pico-scale satellite constellations that reduces launch costs by up to 87 %, simplifies integration, and enables the simultaneous deployment of multiple satellites. The research is divided into three key components. First, the structural design is developed to accommodate eight PocketQube-sized satellites within a 1U CubeSat frame, while remaining scalable. The design is evaluated using finite element analysis and mechanical testing, including modal analysis, vibration, shock, and static load tests, all in accordance with ECSS launch qualification guidelines.. Second, constellation dispersal is addressed through tailored differential drag control algorithms. This approach calculates separation velocities and timing to achieve in-plane phasing, accounting for the operational parameters introduced by the PQ8 form factor. Two case studies with orbital simulations validate the method’s effectiveness and scalability. Third, a novel disengagement mechanism is presented, in which magnetorquer coils are reconfigured to act as synchronized electromagnetic actuators. The circuitry is validated through simulation and bench-top testing, and actuator forces are confirmed via finite element analysis. Overall separation dynamics are then demonstrated using a pendulum testbed to emulate near-free-body translational and rotational disengagement behaviour. Together, these contributions, structural innovation, coordinated dispersal, and integrated separation, form a robust and cost-effective platform for small-satellite constellations. The PQ8 Architecture significantly lowers the barriers to entry and enables missions that would otherwise be financially or logistically infeasible. Description: Ph.D.(Melit.) 2025-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/146877 Title: Developing an immersive learning environment for engineering education and re-skilling, using metaverse technologies Abstract: Industry 4.0 and 5.0 demand engineers with higher-order competencies, that can be difficult to cultivate through traditional lecture-based instruction alone. Immersive technologies offer potential solutions, yet existing research has focused on single-user applications, leaving collaborative metaverse affordances relatively underexplored. The absence of structured frameworks for developing metaverse educational environments further hinders adoption. This thesis investigates metaverse-based learning environments for educational outcomes within manufacturing. The research addresses three gaps: the lack of structured frameworks, the limited exploration of how immersive technologies can support learning of complex interdependent concepts, and the underutilisation of multi-user collaborative affordances. The MITE (Metaverse Immersive Training Environment) framework was developed, integrating Design Thinking with educational models including TPACK, Constructive Alignment, and the 5E instructional model. The framework was validated through a proof-of-concept prototype targeting Quality Assurance and Process Layout Optimisation. These topics exemplify the interconnected nature of modern manufacturing yet are typically taught in isolation. The prototype integrates both disciplines within a collaborative virtual manufacturing environment, enabling realtime collaboration with complex scenarios. A comparative evaluation study compared Learning Outcomes (LOs) between those receiving the metaverse experience and traditional instruction alone. Results indicated that the metaverse group outperformed the traditional group across all measures: mean knowledge scores of 44.69 compared to 41.04 out of 60, greater confidence gains, and completion rates of 84% compared to 63%. The effect size of 0.44 exceeds the average effect of educational interventions, representing a practically significant improvement in LOs and engagement. This research contributes a replicable framework for developing metaverse-based learning environments, empirical evidence supporting immersive collaborative learning for complex engineering topics, and demonstrates the value of multi-user metaverse over single-user VR in developing teamwork and systems thinking competencies demanded by Industry 4.0 and 5.0. Description: M.Sc.(Melit.) 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/145633 Title: Surface engineering of wire arc additively manufactured AZ80 magnesium alloy Abstract: This study investigates the surface engineering of wire arc additively manufactured (WAAM) AZ80 magnesium alloy, focusing on the combined effects of process parameters, heat treatment, and shot peening on its microstructure and mechanical performance. WAAM AZ80 was produced using two processing conditions: one producing materials with higher defect content (P1) and the other yielding a densified, near-defect-free condition (P2). Specimens were extracted along both parallel and perpendicular to the build direction to assess anisotropy, and benchmarked against wrought EN AW-6082 aluminium alloy in the T6 condition. The findings showed that process-induced defects strongly influenced tensile anisotropy, whereas T6 heat treatment improved ductility, hardness, and tensile strength, reducing orientation-dependent disparity and bringing the mechanical properties closer to EN AW-6082. Compression strength exhibited limited sensitivity to defect content. Shot peening further enhanced the surface integrity by inducing grain refinement, work hardening, and CRS, though at the expense of increased roughness. The surface hardness increased by up to 45% in WAAM AZ80 and by 14% in EN AW-6082, while peak CRS reached ~110 MPa in WAAM AZ80 and ~280 MPa in EN AW-6082. Fatigue life improvements were most pronounced in WAAM AZ80, with shot peening extending life by up to 160%, depending on the printing and associated defect orientation, and enabling run-outs beyond 106 cycles in P2 samples through delayed crack initiation and reduced surface-connected porosity. Although EN AW-6082 retained higher absolute fatigue strength, the results demonstrate that refined process control, T6 heat treatment, and shot peening can collectively transform WAAM AZ80 into a competitive lightweight alternative for aerospace and satellite applications, particularly under cyclic loading conditions. Attempts to improve electrical performance through gold coatings highlighted the challenges of plating reactive magnesium alloys. While electroplating failed to achieve uniform coverage, sputtered coating produced more continuous films but did not significantly enhance conductivity, underscoring the need for tailored pretreatments and interlayers for functional integration. Description: M.Sc.(Melit.) 2025-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/145392 Title: Development of a PMMA/TiO2/LO nanocomposite for aquatic environments Abstract: Structures and vessels exposed to water are susceptible to corrosion and fouling due to multiple factors such as the complex biology present in these environments. Hence, it is important that new materials are investigated, combining durability and anti-fouling properties. To tackle this, the work in this project investigated a nanocomposite material, that consisted of a polymethyl methacrylate matrix and titanium dioxide nanoparticles encasing linseed oil as the dispersed phase. The development of the material and evaluation of its durability, anti-fouling properties and leaching of ions into the environment were the main objectives of this project. Samples were prepared using the doctor blade technique, applying a film containing 8.6, 14.8 and 28.3 wt% titanium dioxide nanoparticles on to glass substrates. To assess the durability of the material, salt-spray testing was conducted to simulate environmental conditions while leaching testing was carried out in deionised water. Prior to the salt-spray testing, the weight, wettability and surface roughness of the samples were assessed. These properties were also assessed just after the salt-spray testing and after two weeks. Optical microscopy was conducted to assess the self- healing capabilities of the material. The results showed that contact angle as well as the surface roughness of the nanocomposite increased with an increase in wt% of the nanoparticles. After salt-spray testing, the contact angle decreased while the surface roughness increased. This trend continued after the two weeks were allowed to assess any self-healing. It was noted that the nanocomposite was prone to degradation as well as showing significant adherence issues. Trends towards self-healing properties were noted within the 28.3 wt% samples that underwent both salt-spray testing as well as the leaching testing, but this was not conclusive. The liquid from leaching testing was extracted and analysed using inductively coupled plasma mass spectrometry. The leaching testing indicated that the 28.3 wt% samples leached less than 1 ng/mL of titanium ions. The anti-fouling tests conducted involved assessing the growth inhibition of the nanocomposite against both marine and freshwater algae. All the samples exhibited anti-fouling properties that were not significantly different to PMMA. They showed sufficient growth inhibition against the freshwater algae while being less effective against the marine algae, showing differing results for the latter. The material developed was not durable as would be necessary for the aquatic environment. However, the nanocomposite provided good anti-fouling properties while keeping Ti ion leaching into the environment below the threshold. Description: M.Sc.(Melit.) 2026-01-01T00:00:00Z