Doctoral School

Reading date: 18/06/2025

• LÓPEZ MILLÁN, MARILYN: La reconversión de los espacios portuarios, en el puerto de Balboa en el pacífico de Panamá. Propuesta de mejora de la operativa mediante un modelo de optimización.
  
  Author: LÓPEZ MILLÁN, MARILYN
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MARINE SCIENCES
  Department: Department of Civil and Environmental Engineering (DECA)
  Mode: Normal
  Deposit date: 15/05/2025
  Reading date: 18/06/2025
  Reading time: 14:00
  Reading place: Sala de Juntas de la Facultat de Nautica de BarcelonaPla de Palau, 1808003 Barcelona, Espanya
  Thesis director: MARTINEZ DE OSÉS, FRANCISCO JAVIER
  Thesis abstract: The coexistence of ports in the Panamanian Pacific with their surroundings requires everyone to have access to the ability to move around in an organized and spontaneous manner. The Port of Balboa, one of the most important centers in Panama's logistics chain and international trade, faces a series of operational challenges due to high demand and the complexity of its workflow. Efficient management of wait times and scheduling for carriers is one of the critical areas that directly impacts productivity and user satisfaction.To develop the studies, various surveys and interviews were conducted to understand the movement times outside and inside the terminal, as well as the arrival and approach of vessels to the terminal.Based on this diagnosis, a mathematical optimization formula was developed that took into account various factors, such as cargo volume, type of transport, truck characteristics, and the availability of port resources. The formula sought to reduce carrier wait times by assigning appointments more efficiently and in line with the port's actual capacity. To achieve this, optimization and mathematical programming techniques were used, which allowed for the establishment of a more precise methodology for appointment management.In this context, this research focused on developing a mathematical solution. Based on the results, a custom mathematical model was developed in Python that could be extrapolated to other terminals. This model seeks to generate operational efficiency and minimize long wait times outside the facilities. This model also fosters a positive relationship with the surrounding community.This research demonstrates the feasibility of applying optimization methods and advanced technological tools in ports and logistics terminals, contributing to improved appointment management and optimized wait times. The successful implementation of this formula at the Port of Balboa could be replicated at other ports and logistics points, offering a scalable solution to optimize service to carriers, reduce operating costs, and improve efficiency in international trade.The findings highlight that establishing an adequate flow to serve truck drivers by scheduling appointments to minimize wait times minimizes both the average truck service time and the total service time for all trucks during the day. Furthermore, queques and congestion around port facilities are eliminated.
  

• MARTÍN GIL, KEVIN: Thermal-hydraulic Scaling Distortions in Pressurized Water Reactors
  
  Author: MARTÍN GIL, KEVIN
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN NUCLEAR AND IONISING RADIATION ENGINEERING
  Department: Department of Physics (FIS)
  Mode: Normal
  Deposit date: 10/04/2025
  Reading date: 18/06/2025
  Reading time: 11:00
  Reading place: Aula C3 del Pavelló C, planta 1, ETSEIB
  Thesis director: FREIXA TERRADAS, JORDI | MARTÍNEZ QUIROGA, VÍCTOR MANUEL
  Thesis abstract: Ensuring safety in Nuclear Power Plants (NPPs) requires a deep understanding of their phenomenology, in the context of the deterministic safety assessment. Scaling plays a key role in this understanding, as it is necessary to downscale the complex thermal-hydraulic systems of NPPs to the scale of Integral Test Facilities (ITFs) for research. Constructing a full-scale NPP for experimental purposes is not economically feasible, making downscaling an essential approach. However, achieving a perfect scale model is impossible, as neither engineering nor scientific designs can fully satisfy all scaling requirements to preserve phenomena across different scales.This thesis investigates scaling distortions in several accident scenarios, including the Intermediate Break Loss-of-Coolant Accident (IBLOCA), Steam Generator Tube Rupture (SGTR), and a Main Steam Line Break (MSLB) in a Pressurized Water Reactor (PWR). The research examines the impact of preserving environmental heat losses and the Froude number in horizontal legs, as preserving the latest is essential for stratification, which influences droplet entrainment and reflooding in LOCA scenarios. Additionally, environmental heat losses play a crucial role in replicating plant energy balance, both of which significantly affect coolant discharge through the break. The study also assesses the effects of two different scaling approaches on heat losses and their associated distortions. Furthermore, this research aims to propose methodologies for quantifying, reducing, and mitigating scaling distortions in these scenarios.In this thesis, the Power-to-Volume Scaling Tool (PVST), which is based on the Power-to-Volume scaling methodology, was modified to automate input and output processing, also allowing for downscaling capabilities. Coupled with pre- and post-processing scripts, this modification enabled automated batch generation of validated hybrid and Scaled nodalizations for RELAP5 at any scale. These nodalizations were then used to simulate all the aforementioned scenarios and post-process the results. The hybrid and scaled nodalizations are based on the OECD/NEA ROSA-2 project in the Large-Scale Test Facility (LSTF). These nodalizations employ multiple scaling rationales, varying the treatment of horizontal legs and heat losses, either preserving or not preserving the Froude number and ideal heat losses.Additionally, a first-of-its-kind Best Estimate Plus Uncertainty Plus Scale (BEPU-PS) methodology-built upon the BEPU GRS method with the added incorporation of scaling considerations-was applied to Test 2. This approach preserved ideal heat losses and the Froude number in horizontal legs to quantify scaling distortions in a wide range of scale and compare them to the inherent uncertainties of the ITF and RELAP5.The main phenomenology of the studied scenarios was analyzed across multiple scales and scaling rationales. In IBLOCA scenarios, scaling distortions were observed when the Froude number was not preserved in horizontal legs and when ideal heat losses were not maintained, leading to variations in Peak Cladding Temperature (PCT) and changes in coolant distribution within the primary system of the PWR hybrid-scaled design. Additionally, scaling rationales that preserved ideal heat losses and the Froude number tended to reduce scaling distortions related to PCT, mass distribution, and the timing of emergency core cooling system injections. The BEPU-PS scales bands, along with Spearman's rank correlation coefficients, revealed that the primary contributors to widening the BEPU bands were the discharge coefficient, the scaling number parameter had a significantly lower statistical relevance according to Spearman's rank correlation coefficients.Regarding SGTR-MSLB scenarios, the study highlighted that SGTR scenarios exhibited no significant scaling distortions when the L/Dh ratio was. Additionally, no evidence of scaling distortions was found in MSLB scenario.
  

• WOODWARD RIQUELME, ALEJANDRO BENJAMÍN: Contextual Speech Recognition
  
  Author: WOODWARD RIQUELME, ALEJANDRO BENJAMÍN
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS
  Department: Department of Signal Theory and Communications (TSC)
  Mode: Normal
  Deposit date: 02/04/2025
  Reading date: 18/06/2025
  Reading time: 10:00
  Reading place: Aula de Teleensenyament (Edifici B3 - Ricardo Valle Sala 103 Planta 1, Campus Nord)
  Thesis director: MARQUES ACOSTA, FERNANDO | VARAS GONZÁLEZ, DAVID
  Thesis abstract: Although Automatic Speech Recognition (ASR) technology has achieved remarkable improvements in transcription accuracy in recent years, it still struggles to correctly transcribe certain words. In particular, proper nouns often exhibit lower accuracy due to their unique pronunciations and alternative spellings. To address these challenges, contextualisation is commonly integrated into ASR models to improve the transcription of rare proper nouns and disambiguate between similar-sounding proper nouns.This industrial PhD thesis focuses on the development of contextualisation systems for ASR models. The ASR technology employed in this thesis is used to generate automatic transcripts for podcast content. The objective of the contextualisation system is to improve the accuracy of proper nouns; for example, the names of podcast shows, hosts, and guests.The contextualisation system developed in this thesis is composed of two parts. First, an ingestion pipeline gathers proper nouns relevant to the podcast episode to be transcribed. This pipeline has an automated component that extracts proper nouns from the metadata of each podcast episode, such as the title and description, using tools like a named entity recogniser. Additionally, a module that allows the manual addition of proper nouns to specific podcast shows has been developed. The second part, which represents the most relevant contribution of this thesis, is a novel ASR contextualisation algorithm based on deep neural networks. The contextualized ASR model utilises the gathered proper nouns, resulting in an improvement in accuracy when compared to the same model without contextualization capabilities.The accuracy of the ASR system developed in this thesis is evaluated and analysed using episodes from popular public podcast shows. A human evaluation of the word error rate was employed during this assessment.This evaluation compares the quality of the ASR model system's transcripts to those provided publicly by the podcast content creators. The results show that the system developed in this thesis produces transcripts that contain four times fewer errors than the transcripts offered by podcast hosting providers.The contextualization method is also evaluated on a public dataset and compared to state-of-the-art methods. The results show that the contextualization method proposed in this thesis significantly outperforms the existing systems.
  

Reading date: 19/06/2025

• RIU PERDRIX, GUIOMAR: Dry-electropolishing of WC-Co cemented carbides: Chemical, microstructural and mechanical characterization
  
  Author: RIU PERDRIX, GUIOMAR
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
  Department: Department of Materials Science and Engineering (CEM)
  Mode: Article-based thesis
  Deposit date: 06/05/2025
  Reading date: 19/06/2025
  Reading time: 11:00
  Reading place: ESCOLA D'ENGINYERIA DE BARCELONA EST AV. d'Eduard Maristany, 16 08019 Barcelona 934137400 Sala Polivalent Planta A 0 (A.0.3) https://eebe.upc.edu/es
  Thesis director: ROA ROVIRA, JOAN JOSEP | LLANES PITARCH, LUIS MIGUEL
  Thesis abstract: WC-Co cemented carbides are widely used in industry, particularly for cutting tools, due to its exceptional combination of mechanical properties. They are composites consisting of tungsten carbide (WC) particles embedded within a cobalt (Co) metallic binder. This microstructural assemblage provides a unique combination of hardness, wear resistance, and fracture toughness. However, these properties can degrade at high temperatures (>500 ºC) due to corrosion sensitivity. To address this limitation, protective coatings, such as titanium aluminium nitride (TiAlN) or titanium silicon nitride (TiSiN) are frequently applied, enhancing performance under high-temperature loading.Grinding is the most conventional post-processing technique used to achieve the final geometry and dimensional tolerances of WC-Co components. However, this method impacts surface integrity, inducing defects like voids, cracks, high roughness (0.2 - 0.6 µm), phase transformations in the metallic Co binder, and compressive residual stresses, extending up to 10-20 µm in depth. Accordingly, removal of the damaged layer though polishing is commonly advised.In recent years, a new dry-electropolishing technology has emerged for metallic alloys, allowing precise defect reduction and surface improvement. Unlike conventional electropolishing, which uses liquid electrolytes, dry-electropolishing uses solid porous polymeric particles (ion exchange resins) filled with an electrolytic medium. This method selectively removes material layer-by-layer from surface irregularities, reducing roughness and improving surface quality.This industrial Ph.D. thesis focus on the development of a novel dry-electrolyte specifically tailored for electropolishing WC-Co composites using DryLyte® Technology. The research explores the underlying polishing mechanisms, optimizes electrical parameters, and identifies key chemical reactions involved in the process. Results demonstrate that this process effectively eliminates surface defects, reduces roughness, and preserves the WC-Co microstructure, avoiding Co leaching and WC embrittlement.A comparative microstructural and mechanical analysis was conducted, evaluating various shaping and finishing methods, including grinding, electrical discharge machining (EDM), conventional polishing, and dry-electropolishing. The findings reveal that, while grinding and EDM are widely used, they generate surface defects such as micro-cracks, porosity, and harmful oxides. Conventional polishing improves surface roughness but removes hundreds of microns of material and fails to preserve compressive residual stresses, thereby diminishing the mechanical performance of the system. Conversely, dry-electropolishing precisely eliminates deformed layers, achieves smooth surfaces between phases, and retains beneficial compressive residual stresses.The thesis further explores the industrial applications of this technology, such as cutting edge preparation for WC-Co end-mill tools. Previous studies have demonstrated that an optimal edge preparation increases tool life. The results of this research confirm that dry-electropolishing can fine-tune the cutting edge radius, refine micro-geometric parameters, reduce roughness, and eliminate manufacturing-induced defects. A direct correlation between polishing time and micro-geometric parameters is established, showing rapid changes within the first three minutes, followed by stabilization.Additionally, the research investigates the stripping of worn TiAlN/TiSiN coating on WC-Co substrates to extend their operational lifespan and reduce costs. This process removes the films precisely, leaving an oxide surface layer without compromising the substrate microstructure. The process demonstrates a linear relationship between polishing time and remaining coating thickness, ensuring a controllable, efficient, and homogeneous method.
  

Reading date: 20/06/2025

• CARREÑO MEGIAS, XAVIER: Ground-based GEOSAR system using DVB-S/S2 signals of opportunity and FPGA based correlators
  
  Author: CARREÑO MEGIAS, XAVIER
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS
  Department: Department of Signal Theory and Communications (TSC)
  Mode: Normal
  Deposit date: 06/05/2025
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: BROQUETAS IBARS, ANTONI
  Thesis abstract: The SAR satellite missions from Geostationary Orbits (GEOSAR) offer short revisit times of less than 24 hours, which are essential for monitoring fast-evolving phenomena. A first mission has recently been launched in China, and other missions are being studied or proposed in Europe and the USA, with applications ranging from water cycle monitoring to terrain stability assessment. All of these missions share the need for precise orbit determination at Geostationary Orbits (GEO) to enable the formation of well-focused SAR images.By employing Field-Programmable Gate Array (FPGA) technology, digital correlators have been designed to be used in an interferometric orbit determination system. The system has been validated for obtaining orbital estimates using phase observables from the correlator outputs, which can be used to determine the satellite's trajectory. The implemented system tracks TV broadcasting telecommunication satellites, using the transmissions as signals of opportunity (SoOp). Urban reflectors are utilised to form large interferometric baselines with respect to the developed receiver.Precise orbital determination is crucial for Synthetic Aperture Radar (SAR). Simulation studies were conducted for a monostatic configuration and a ground-based bistatic configuration to assess the impact of orbital parameter estimation errors on SAR image focusing. An autofocusing technique based on entropy minimization optimisation has been studied to improve the focusing of the GEOSAR images affected by residual orbital errors, allowing for the relaxation of orbit precision requirements to the order of hundreds of metres. Using the same transmitters of opportunity as in the interferometric system, a ground-based SAR (GB-GEOSAR) passive system has been designed and implemented. A multichannel coherent receiver is employed to capture echo data from a close by urban scene. A range compression module, based on the design of the interferometric correlators, is employed to process the echo data by correlating it with the main satellite signal, which acts as a reference for the matched filter process. Azimuth compression, based on the orbital data from the interferometric system, is then applied to obtain SAR-focused images. These images can be used to study GEOSAR concepts and serve as proof of concept for the capabilities of a passive system, which could be employed for monitoring local regions with low deployment costs.Interferometric and polarimetric techniques can be applied to GB-GEOSAR images, which could be used in topographic or earth deformation mapping and surface type classification. An experimental evaluation based on images of urban and mountainous areas near the university campus has enabled the identification of the challenges, potentials, and limitations of the developed system.