Engineering & Physical Sciences
Permanent URI for this communityhttps://dspace-upgrade.is.ed.ac.uk/handle/10399/17
Browse
1985 results
Search Results
Item Underwater visual acoustic SLAM with sensor calibration(Heriot-Watt University, 2025-03) Xu, Shida; Wang, Doctor SenUnderwater environments present significant challenges for visual Simultaneous Localization and Mapping (SLAM) systems due to limited visibility, poor illumination, and the sporadic loss of structural features in images. To address these issues, this thesis focuses on underwater SLAM by fusing data from a Doppler Velocity Log (DVL), stereo cameras, and Inertial Measurement Unit (IMU) within a graph optimization framework. Additionally, we propose an extrinsic and DVL transducer calibration algorithm that estimates the extrinsic parameters and DVL transducer orientation without requiring additional setups. Furthermore, a novel observability-aware, entropy-based active calibration method is introduced to actively search for the next optimal poses for reliable calibration. Extensive experimental results demonstrate that our proposed SLAM system surpasses state-of-the-art underwater and visual-inertial SLAM systems in terms of localization accuracy and robustness, and highlight the precision of our calibration algorithm.Item Advancing techno-economic assessment for emission reduction technologies in the cement industry(Heriot-Watt University, 2025-03) Strunge, Till Moritz; Van der Spek, Associate Professor Mijndert; Renforth, Professor PhilThe cement industry, characterised by low profit margins, accounts for approximately 7% of anthropogenic greenhouse gas emissions and has the highest carbon intensity per unit of revenue among all industries. To achieve full decarbonisation of this sector, it is essential to develop economically viable strategies that incentivise CO2 emission reductions. To guide policymakers and decision-makers from industry or academia in search of decarbonisation strategies, ex-ante system analysis tools including techno-economic assessments (TEA) are essential. This thesis advances techno-economic assessments of emission reduction technologies in the cement industry, both by conducting crucial assessments that have been lacking in this field (e.g., investigating potential business cases for CO2 mineralisation technologies) and by providing guidance for modellers on good and maybe bad practices in TEAs of emerging technologies, aiming to provide actionable insights for policymakers, industry decision-makers, and researchers. The research addresses three key questions, each explored in a peer-reviewed article. First, it evaluates the role of CO2 mineralisation in creating economically viable pathways to net-zero emissions. The results indicate that CO2 mineralisation using virgin minerals could reduce emissions by 8-33% at optimal plant sizes, with potential for profitability when supplementary cementitious materials (SCMs) are produced. This suggests CO2 mineralisation could be a transitional technology in the decarbonisation of cement production. Second, it demonstrates the critical role of uncertainty analyses in TEAs, advocating for the use of global sensitivity analysis methods to enhance transparency and reliability in decision-making. Third, it assesses least-cost decarbonisation strategies across different European regions using geospatial modelling, considering plant locations and potential synergies between industrial actors. The results highlight significant regional cost variations and underscore the importance of coordinated efforts among industry stakeholders to minimise decarbonisation costs. Overall, this thesis provides actionable insights into economically viable emission reduction strategies in the cement industry while offering methodological advancements for TEAs . By integrating uncertainty analyses and geospatial considerations, it contributes to the development of robust, evidence-based decarbonisation pathways.Item Bayesian methods for online real-time 3D imaging in challenging environments using single-photon LiDAR data(Heriot-Watt University, 2025-03) Drummond, Kristofer; Altmann, Doctor Yoann; McLaughlin, Professor StephenSingle-photon LiDAR (SPL) continues to gain interest in a variety of different applications. With LiDAR technology being deployed more outside of lab based conditions, it is critical to investigate methods for providing real-time scene reconstruction while reducing, in a principled way, the effects of noise and uncertainties caused by photon scattering environments, which is the aim of this thesis. Traditional 3D ranging methods for SPL usually perform surface detection and range estimation sequentially, alleviating the computational burden of joint detection and estimation. Furthermore, traditional approaches construct and process detected photon time of arrival (ToA) histograms to obtain final target depth estimates. However processing large data volumes over long temporal sequences results in undesirable costs in memory requirement and computational time. Adopting a Bayesian formalism, the initial joint detection/estimation problem is formulated as a single inference problem. Intractable integrals involved with variable marginalization in the Bayesian calculations are avoided by discretising variables, recasting the resulting problem as a model selection/averaging problem. A further approach is then investigated by using online Assumed Density Filtering (ADF) strategies to process SPL data on-chip without the need for histogram data construction. Additional benefits of the proposed methods are demonstrated by providing a conservative approach to uncertainty quantification of the calculated depth estimates, and real time analysis from the results. Statistical approaches can be limited by user defined input parameters and prior information. Finally, an approach is proposed using recursive Bayesian estimation to implement a detect-and-track method to SPL data processing which incorporates the inference information obtained from the previously mentioned joint detection/estimation approach. To avoid intractable calculations when computing the model parameters, a spatio-temporal correlation approach is proposed between individual model parameters to improve the quality of scene reconstruction. The benefits of the proposed methods are illustrated using synthetic, real SPL data for outdoor targets at up to 8.6 km as well as real data of underwater targets at up to 7.5 attenuation lengths from the LiDAR system.Item Continuous and ultra-compact LiDAR mapping and localisation(Heriot-Watt University, 2025-03) Zhang, Kaicheng; Wang, Doctor Sen; Kong, Doctor Xianwen; Petillot, Doctor YvanRecently, Light Detection and Ranging (LiDAR) has gained prominence in robotics and autonomous driving for capturing precise environmental geometry, essential for simultaneous localisation and mapping (SLAM) and navigation. However, storing and updating large-scale high-definition maps presents significant challenges, making the development of memory-efficient, updatable, and localisable map representations crucial for advancing SLAM systems in dynamic environments. In this thesis, we present a series of advancements in LiDAR-based SLAM systems aimed at achieving memory-efficient representation, continuous reconstruction, and global mapping. The term continuous reconstruction refers to a continuous function that allows sampling 3D points at any resolution. We firstly introduce CURL (Continuous, Ultra-compact Representation for LiDAR), which leverages spherical harmonics (SPHARM) basis functions to encode point clouds, achieving effective compression and continuous reconstruction while outperforming contemporary deep learning methods. Building on this foundation, we propose CURL-MAP, an extension of CURL for mapping with pose estimation capabilities, utilising a set of bounding boxes containing SPHARM-encoded patches to construct a global map. To build a globally consistent map, we develop CURL-SLAM, which contains a customised CURL-based bundle adjustment (BA) with pose graph to ensure global consistency, even in large-scale scenarios and further increase the efficiency of the system by replacing quasi-conformal mapping with a mask-based method for identifying valid regions. These modifications reduce computational requirements and storage space, facilitating the integration of all newly observed patches and enhancing system robustness. Overall, CURL, CURL-MAP, and CURL-SLAM collectively offer a memory-efficient, updatable, and localisable 3D dense map representation, supporting continuous reconstruction for robust SLAM applications.Item Computationally-enhanced electro-optical sensing(Heriot-Watt University, 2025-02) Scholes, Stirling; Leach, Professor JonathanAbstract and full text unavailable. Restricted access until 28.02.2035. Please refer to the PDF.Item Co-design of direct radiating array architectures and radio resource management for future broadband satellite communication systems(Heriot-Watt University, 2025-03) Pellet, MargauxOVER the past years, with the transition from broadcast to broadband satellite communications, active direct radiating arrays have been seen as a key solution to guarantee high performance in terms of capacity, flexibility and reconfigurability. Such configuration gives a full flexibility in terms of coverage as beams can be steered along any desired direction within the field-of-view. However, the hardware complexity of such antenna configurations is unaffordable particularly in light of today’s on-board processors. The technological requirements lead to unrealistic architectures, especially for GEO coverages where thousands of radiating elements are needed. The proposed overlapping strategies with hybrid beamforming guarantee very strong performance by mitigating some unwanted interfering lobes which are particularly critical for satellite communications, while reducing the number of control points. While optimizing the antenna architecture is a key for reaching very high throughput, another challenge is the resource allocation. Frequency, time, beams, and power management must be achieved in order to avoid latency during the communication and fulfil the capacity demand. A full methodology is proposed in the thesis, considering a dual optimization of both the antenna architecture and a new resource allocation strategy in terms of throughput and time complexity.Item The effect of in-situ fiberglass reinforcements on the mechanical and tribological properties of 3D printed parts(Heriot-Watt University, 2025-02) Ismail, Khairul Izwan Bin; Chuen, Associate Professor Ir. Doctor Yap Tze; Ahmed, Associate Professor Doctor RehanFused filament fabrication (FFF) has been a widely used manufacturing method in the past decade. It operates through additive manufacturing (AM), where thermoplastic material is melted layer by layer to create a product, competing with traditional methods like injection moulding or subtractive techniques such as milling, drilling, and turning, Nevertheless, thermoplastic products produced through FFF often exhibit inferior mechanical properties when compared to their injection moulded counterparts. This research addresses these limitations by employing fibre-reinforced thermoplastics to enhance the mechanical strength of printed parts, improving interlaminar bonds and reducing voids between layers. A prototype fibre-doser was developed and optimized to deposit in-situ short fibre reinforcement during the FFF process, enabling the fabrication of fibre-reinforced thermoplastic composite parts. The fibre-doser was constructed using high strength materials to ensure precision and durability. It is able to produce composites with varying fibre contents, offering adaptability for diverse applications. Specimens prepared following ASTM standards underwent thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and mechanical tests, including tensile, flexural, impact, and tribological assessment. Results showed that the inclusion of glass fibre enhanced tensile strength by up to 45% and impact resistance by approximately 60%, with a modest 15% improvement in flexural strength. Tribological test revealed a 35% reduction in wear rate due to the reinforcing effect of the fibres. SEM analysis confirmed uniform fibre distribution and improved interlaminar bonding, while TGA indicated enhanced thermal stability. These findings demonstrate that the fibre-doser effectively produces high-strength composite materials using FFF, overcoming the limitations of traditional FFF parts. The advancements achieved in mechanical and tribological properties expand the potential of 3D-printed components for demanding engineering applications such as prostheses, gears, bearings, and linkages, thus extending the capabilities of FFF technology.Item Developing novel 3D bioprinting techniques to create pancreatic cancer models(Heriot-Watt University, 2025-02) Porcza, Laura Melinda; Leslie, Professor Nicholas R.; Melchels, Doctor FerryCancer is a leading cause of death worldwide, with pancreatic ductal adenocarcinoma (PDAC) having the lowest survival rates among all cancers, which have not improved in the past 50 years. PDAC tumours are characterised by a stiff, fibrotic stroma, which contributes to the cancer’s aggressiveness and chemoresistance. Over the past decade, 3D bioprinting techniques have gained popularity for their potential to create complex, biomimetic 3D in vitro models, which recapitulate native tissue responses. However, developing 3D bioprinting techniques requires addressing several challenges, primarily bioink biocompatibility and printability, as well as long-term cell survival and behaviour. In this present study, a novel 3D bioprinting method was developed using droplet-based bioprinting technologies. Optimisation studies of bioprinting parameters demonstrated that using an electromagnetic droplet (EMD) printhead, droplets of cell-laden GelMA bioinks can be extruded with accuracy and precision. Additionally, two different support materials were explored to deposit the droplets into: a gellan gum granular gel suspension medium and pure Matrigel. Both methods showed that by adjusting the printing conditions, such as bath temperature or extrusion pressure, the size and definition of the hydrogel droplets can be controlled. Furthermore, this method enabled multilineage cell patterning, the Matrigel-based constructs demonstrating enhanced cell viability, proliferation and functional activity. Lastly, Matrigel was combined with a low-temperature gelation GelMA formulation to increase its mechanical properties and offer a more robust microenvironment without losing its inherent biocompatibility and support for cellular functions. Despite some remaining limitations, such as achieving high resolution printing and scalability, this novel method offers a unique tool for creating Matrigel rich 3D bioprinted cancer models. Its customisation and reliability make it an appealing approach, which can be adapted to a variety of tissues and pathophysiological conditions. Further development of this method could transform it into a powerful tool in the 3D bioprinting field.Item Investigation of mechanical and structural properties based on bond development under different printing conditions in fused deposition modelling(Heriot-Watt University, 2025-02) Pang, Rayson; Kou, Doctor Lai MunFused Deposition Modelling (FDM) 3D printing presents a compelling alternative to conventional manufacturing methods from a professional research perspective. Its unique attributes address key challenges inherent in traditional manufacturing paradigms. As such, FDM emerges as a catalyst for advancing manufacturing practices, offering researchers avenues for exploration in efficiency, sustainability, and design innovation. One of the main obstacles of FDM technologies is the poor mechanical properties of fabricated parts, resulting in the lack of functionality and its low production rate. The research centred on a systematic exploration of temperature-associated printing parameters within the domain of FDM. Temperature measurement techniques were employed to track temperature changes during printing and cyclic heating based on different printing parameters. Next, the physical dimensions of printed rasters was correlated with bonding mechanisms, and their effect on mechanical properties (e.g. tensile, flexural, impact strengths) was quantified. As an auxiliary study, the research was also supplemented with investigations on other printing parameters such as printing speed, layer height, deposition sequence and raster orientation which also affected the temperature development during the printing process. The research findings provided crucial insights into the ramifications of printing parameters that induced temperature changes. In the present work, the underlying mechanism of physical bonding between printed rasters were investigated and related to the mechanical properties of fabricated parts. Results showed that changes to printing temperature was most significant due to its reheating effect on previously deposited layers. This promotes the spreading of deposited rasters resulting in a reduction of size and percentage of voids was observed when cross section of the fabricated parts were examined. It was ascertained that the mechanical properties improved due to better developed physical bonds when printing temperature increases due to its reduced viscosity. By refining printing parameters in accordance with the findings, users can achieve superior mechanical performance. Thereby, they can enhance the applicability of FDM technology across various industries and driving advancements in additive manufacturing methodologies, fostering innovation and efficiency in production processes.Item Analysis and origin of characteristic aroma of whisky matured in ex-red wine casks(Heriot-Watt University, 2021-03) Katsuki, Yuichiro; Maskel, Doctor Dawn; Hill, Doctor AnnieTraditionally, ex-bourbon and ex-Sherry casks are used for maturation of Scotch whisky. Recently however, maturation in other types of cask such as ex-red wine casks or rum casks has become popular as a method to extend the flavour profile. For example, whisky matured in ex-red wine casks has a characteristic, strawberry-like, sweet and sour aroma. We have investigated the key components of the characteristic sweet aroma imparted during ex-red wine cask maturation using fractionation techniques and mass spectrometry-olfactometry (GC/MS-O). The results of fractionation experiments showed that the sweet aroma was found in the neutral and mid-polar fraction. The results of GC/MS-O analysis of the neutral and mid-polar fraction showed that 2-heptanone, 2-nonanone, 1,1-diethoxyethane, diethyl succinate, γ-nonalactone and trans-oak lactone provided sweet, fruity and green aromas and were present at higher concentrations in ex-red wine cask matured whisky compared to remade hogshead cask matured whisky. In addition, spiking tests revealed that whilst each of these compounds individually contributed to the sweet character, it was the combination of all these compounds that gave more complexity and was closer to the target ex-red wine cask character. Furthermore, whilst acidic compounds such as acetic acid, propionic acid, ethyl lactate and 3-hydroxy-2-butanone did not have a sweet aroma, they did enhance this aroma and the ex-red wine cask maturation character. Therefore, these results suggest that the characteristic aroma of whisky matured in ex-red wine casks is complex and attributable to several different compounds.