Theses authorised for defence

DOCTORAL DEGREE IN AEROSPACE SCIENCE AND TECHNOLOGY

• GASPARINO FERREIRA DA SILVA, LUCAS: High-performance low-dissipation algorithms for simulation of turbulent compressible flows
  
  Author: GASPARINO FERREIRA DA SILVA, LUCAS
  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 AEROSPACE SCIENCE AND TECHNOLOGY
  Department: Department of Physics (FIS)
  Mode: Normal
  Deposit date: 03/04/2024
  Reading date: 28/06/2024
  Reading time: 11:00
  Reading place: BSC Auditorium, Planta -1, Plaça Eusebi Güell 1-3, Barcelona
  Thesis director: LEHMKUHL BARBA, ORIOL | MIRA MARTÍNEZ, DANIEL
  Committee:
       PRESIDENT: RUBIO CALZADO, GONZALO
       SECRETARI: JOFRE CRUANYES, LLUÍS
       VOCAL: COLOMBO, ALESSANDRO
  Thesis abstract: Motivated by recent advances in computational technology aiming at exascale capabilities, which implies a need for applicationscapable of taking advantage of these new supercomputing architectures, this work will present two algorithms aimed at implementing an efficient and low-dissipation algorithm focused on LESand DNS of turbulent compressible flows.The basis for the algorithms is the Continuous Galerkin method applied to elements whose nodes and quadrature points areformed from the Gauss-Lobatto-Legendre roots, resulting in a SpectralElements Method. Throughout this work, it will be evidenced that this formulation leads to highly efficient kernels for discretizingthe convective and diffusive terms of the compressible Navier-Stokes equations, with the added benefit that the order of the scheme is coupled with the order of the shape functionpolynomials employed by the elements themselves, significantly simplifying the process of increasing the order of the scheme.To achieve a stable Total Variational Diminishing algorithm, the \acrshort{sem} scheme will be paired with an EntropyViscosity-based stabilization model and a suitable splitting of the nonlinear convective terms will be employed to eliminate aliasing issues that occur in the \acrshort{sem} formulation.This spatial discretization is then coupled with both an explicit and a semi-implicit scheme to account for the temporal nature ofthe flow equations. The explicit version of the algorithm is expected to be simple and efficient per time step, but due to its \acrshort{cfl} condition limitation, the semi-implicit version is alsoproposed to allow for better overall performance incases where the time-step becomes overly limited, such as in wall-bounded flows.Considering the focus on producing a \acrshort{cfd} application towards the exascale future, an important aspect of this work isthat both algorithms are proposed with a full \acrshort{gpu}implementation in mind: the use of accelerators is expected to be a key aspect of future supercomputing architectures, and thus itis important to design these algorithms with this in mind.Examples detailing the performance of both algorithms will be presented both in the case of a single device and when distributedarchitectures using multiple devices are employed.
  
• RADHAKRISHNAN, SARATH: NON-EQUILIBRIUM WALL MODELING IN LES OF HIGH-SPEED TRANSITIONAL FLOWS
  
  Author: RADHAKRISHNAN, SARATH
  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 AEROSPACE SCIENCE AND TECHNOLOGY
  Department: Department of Physics (FIS)
  Mode: Normal
  Deposit date: 05/04/2024
  Reading date: 10/06/2024
  Reading time: 11:00
  Reading place: Sala de Actos Manuel Martí Recober (C/ Jordi Girona 1- 3, Edifici B6, Planta 0, Campus Nord, Barcelona)
  Thesis director: LEHMKUHL BARBA, ORIOL | MIRA MARTÍNEZ, DANIEL
  Committee:
       PRESIDENT: VINUESA MOLTIVA, RICARDO
       SECRETARI: RODRIGUEZ PEREZ, IVETTE MARIA
       VOCAL: ALCÁNTARA ÁVILA, FRANCISCO
  Thesis abstract: Wall-modeled large eddy simulation (WMLES) is a practical tool to perform the wall-bounded large eddy simulation (LES) with less computational cost by avoiding explicit resolution of the region near the wall. However, its use is limited in flows that have high non-equilibrium effects, like separation and/or transition. In this work, three wall modeling strategies are presented, two of them based on high-fidelity data. First, a technique is presented to improve the robustness of the state-of-the-art algebraic wall shear stress model. Second, an equilibrium-data-driven wall shear stress model is developed using the LES of the channel data. The key purpose of this is to estabilish the methodology of model development using high-fidelity data. The model is built using a machine learning technique that uses gradient-boosted regression trees (GBRT). The objective of the model is to learn the boundary layer of a turbulent channel flow so that it can be used in significantly different flows where the equilibrium assumptions are valid. The importance of selecting the appropriate data for training and the importance of choosing the input of the model are described. The model is validated a priori and a posteriori. A posteriori tests are conducted by implementing the model in a multiphysics solver and using it in the turbulent channel flow and in the flow over a wall-mounted hump. The performance of the model is compared with an algebraic wall shear stress model to understand the strengths and shortcomings of the data-based models and further improve the same. In the next step, the model is upgraded to a non-equilibrium wall model by using non-equilibrium data for the training. The high-fidelity data chosen for training include the Direct Numerical Simulation (DNS) of a double diffuser that has strong non-equilibrium flow regions and LES of a channel flow. The ultimate purpose of this model is to distinguish between equilibrium and non-equilibrium regions and to provide the appropriate wall shear stress. The ML system used for this study is also GBRT. The model is tested a priori and a posteriori. A posteriori tests are conducted on the diffuser, channel flows, flow over the hump, and junction flows. These tests showed that the model is very effective for corner flows and flows that involve relaminarization, while it performs rather less effectively in recirculation regions.
  

DOCTORAL DEGREE IN BIOINFORMATICS

• CABRERA PASADAS, MÓNICA: Exploring the impact of p53 activation on spatio-temporal genome topology
  
  Author: CABRERA PASADAS, MÓNICA
  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 BIOINFORMATICS
  Department: Department of Statistics and Operations Research (EIO)
  Mode: Normal
  Deposit date: 27/10/2023
  Reading date: 09/07/2024
  Reading time: 10:00
  Reading place: Sala d'Actes de l'FME, Edifici U, Campus Sud
  Thesis director: JAVIERRE MARTINEZ, BIOLA M | VALENCIA HERRERA, ALFONSO
  Committee:
       PRESIDENT: MARTI-RENOM, MARC A
       SECRETARI: DELICADO USEROS, PEDRO FRANCISCO
       VOCAL: RAMOS RODRIGUEZ, MIREIA
       VOCAL NO PRESENCIAL: STIK, GREGOIRE
       VOCAL NO PRESENCIAL: GÓMEZ MELIS, GUADALUPE
  Thesis abstract: The year I started this Ph.D. (2019) was the 40th anniversary of the discovery of p53 and the 30th anniversary of its characterization as a tumor suppressor. Approximately, half of all human cancers carry mutations or deletions of the p53 gene, while the other half have disruptions to the p53 signaling pathway. Nevertheless, despite decades of extensive research the precise molecular mechanisms underpinning p53-mediated gene regulation and its tumor-suppressive efficacy remain partially elucidated.Under non genotoxic or oncogenic stressed conditions, the MDM2 protein promotes ubiquitination and proteasome-mediated degradation of p53 maintaining low cellular levels. However, upon encountering cellular stress, the p53-MDM2 interaction is disrupted leading to p53 accumulation and activation. Once active, p53 promotes critical cell fate decisions such as cell cycle arrest, apoptosis, or senescence by transactivating an array of target genes, leading to effective tumor regression. Consequently, the loss of p53 functionality is intrinsically linked to cancer susceptibility, rendering p53 an enticing candidate for anti-cancer therapeutic interventions. Cis-regulatory elements master gene expression through the control of transcription in temporal and spatial dimensions. However, the mechanisms by which p53 engages the genome in the context of 3D chromatin to activate transcription are not well understood ¿the interplay between p53 and 3D genome organization has remained unexplored to date.This doctoral thesis investigates p53s ability to reconfigure the genome and govern transcriptional regulation by inducing alterations in the temporal and spatial genome structure. It is the hypothesis of this dissertation that p53 exerts its influence by modulating physical connections between regulatory elements, enhancers, and gene promoters via the manipulation of DNA loops.To rigorously assess this proposition, a comprehensive investigation into the potential ramifications of p53 activation in HCT116 cell lines achieved through pharmacologically inhibiting MDM2 with Nutlin-3a drug has been outlined. This approach synergistically integrates diverse genomic datasets, encompassing Hi-C, Promoter Capture Hi-C, RNA-seq, and ChIP-seq methodologies. The analysis unveils that p53 activation precipitates both direct and indirect modifications in genome architecture, manifesting within minutes of its induction. By deciphering the nexus between 3D genome organization and p53-driven transcriptional regulation, this thesis aspires to help in the unravel avenues for therapeutic intervention in the realm of cancer treatment.
  

DOCTORAL DEGREE IN BIOMEDICAL ENGINEERING

• SAYOLS BAIXERAS, NARCÍS: Cognitive Robot Control Strategies for Complex Surgical Environments
  
  Author: SAYOLS BAIXERAS, NARCÍS
  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 BIOMEDICAL ENGINEERING
  Department: Department of Automatic Control (ESAII)
  Mode: Normal
  Deposit date: 11/04/2024
  Reading date: 04/06/2024
  Reading time: 11:00
  Reading place: Sala d'Actes de la Facultat d'Informàtica de Barcelona (FIB), Edifici B6 del Campus Nord , C/Jordi Girona Salgado,1-3, 08034 BARCELONA Enllaç: https://meet.google.com/gwr-tszj-ham
  Thesis director: CASALS GELPI, ALICIA | HERNANSANZ PRATS, ALBERTO
  Committee:
       PRESIDENT: DALL\'ALBA, DIEGO
       SECRETARI: FRIGOLA BOURLON, MANEL
       VOCAL: AVILÉS RIVERO, ANGÉLICA
  Thesis abstract: This thesis aims to contribute to the development of robotics autonomy in complex tasks based on the cognitive control paradigm. Cognition is a multidisciplinary approach aimed to provide robotic systems with intelligent and autonomous behaviour that should learn and reason about how to respond in front of complex tasks and environments.Cognition involves aspects as perception, awareness, interpretation of human actions, learning, planning, anticipating and dynamic response to changes in the working conditions and in the interaction with humans. Autonomy is intended to partially substitute and/or complement the human faculties at the level of perception, analysis and execution. Increasing the level of autonomy of robots allows focusing the humans cognitive load on high level decisions and actions, in aspects where the human factor is essential: contextualisation of information, specific expertise, medical knowledge and complex decision-making among others. Furthermore, robots improve the properties of humans in certain aspects such as precision, repeatability, absence of fatigue or response efficiency in terms of time and accuracy.This thesis addresses different key aspects of robotic autonomy: perception, planning and dynamic execution of actions and, finally, the control structures required for efficient control and their integration in robotic systems.This thesis combines a global theoretical approach supported by practical applications based on the field of robot-assisted minimally invasive surgery. This field has been chosen for two main reasons: the social impact involved in the improvement of surgery and, secondly, because this field of application is highly demanding from both, human and robotic perspective.The experimental phases have focused on various surgical robotic. First, a teleoperated platform with a single robot has been used aimed at minimally invasive fetal surgery in which a cognitive system offers a certain level of autonomy to generate trajectories in collision-free spaces, increasing patient safety and decreasing the cognitive load of surgeons in navigation and interaction tasks within the intra-uterine region. Second, a multi-robot architecture to execute auxiliary actions in a human-robot cooperative system: the main surgeon performs the surgical actions while the auxiliary robots perform, autonomously, auxiliary surgical tasks. With this configuration the experimentation focuses on minimally invasive radical prostatectomy surgery.Thus, the thesis addresses the perception of the anatomical environment, considering the limitations of data acquisition in terms of quality and quantity, as well as the absence of anatomical markers. The next topic that the thesis addresses is the dynamic planning of actions. Different application paradigms have been studied, such as direct human-robot interaction using haptic guidance, movement planning in pseudo-structured environments and, active planning and control in dynamic environments. These proposed environments respond to different surgical scenarios within minimally invasive techniques.Finally, cognitive control applied to robotic platforms is addressed. The followed approach is based on the multi-level decomposition of complex tasks (e.g. surgical procedure) defining all potential states and transitions. This decomposition translates into the use of deterministic and robust control structures that restrict falling into uncontrollable or unexpected situations that put at risk, in the application case, the patient, the surgeons or the auxiliary personnel.Control structures also consider human-robot interaction, robots coordination and cooperation, interaction with the work environment and restrictions imposed by surgery and patient safety.The integration of all these modules: perception, planning and cognitive control, demonstrates the advances achieved in cognitive robotics and their applicability towards a more autonomous robotic surgery.
  

DOCTORAL DEGREE IN BUSINESS ADMINISTRATION AND MANAGEMENT

• HINOJOSA I RECASENS, JOSEP DOMINGO: Investigación sobre la persistencia, el cambio y la materialidad de la identidad organizacional: entrevistas a expertos y el caso de una empresa centenaria
  
  Author: HINOJOSA I RECASENS, JOSEP DOMINGO
  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 BUSINESS ADMINISTRATION AND MANAGEMENT
  Department: Department of Management (OE)
  Mode: Normal
  Deposit date: 05/03/2024
  Reading date: 30/05/2024
  Reading time: 11:30
  Reading place: Lectura públicaa l' Aula 28.8 de l'Escola Tècnica Superior d'Enginyeria Industrial de Barcelona (ETSEIB)- UPC
  Thesis director: SUNYER TORRENTS, ALBERT
  Committee:
       PRESIDENT: GARCÍA ÁLVAREZ, MARIA ERCILIA
       SECRETARI: PONS PEREGORT, OLGA
       VOCAL: SELVA OLID, CLARA
  Thesis abstract: ContextThis thesis investigates organizational identity, its persistence and change, and the relationship between identity and material objects. Organizational identity is what the members of an organization answer when they ask themselves: Who are we? and what do we do as an organization?. As a field of research, organizational identity has been gaining relevance in recent decades, especially since the authors Albert and Whetten (1985) established the academic foundations to characterize this concept through the attributes that identity must have: centrality, endurance and differentiation. This characterization was generally accepted by the scientific community and was not questioned for years; it is still considered relevant today. Organizational identity is a broad and complex topic that has been explored by various researchers using qualitative methods. Identity can evolve as organizational practices and narratives are reinterpreted. Some authors consider that identity is dynamic and that it can change as the organization evolves. In this thesis we develop an exploratory research on organizational identity, paying special attention to how identity can adapt, change and be instantiated by material objects. Specifically, this thesis has been structured based on two lines of research: The first line of research studies the persistence of organizational identity and its changes over time, the second line explores the possible relationships between the organizational identity and material artifacts.JustificationThere remains an interesting path to follow in research on organizational identity. Currently, organizational identity is part of the strategic debates and communication plans of many organizations, highlighting the relevance of this concept that can be considered the DNA of an organization. The purpose of this research is to deepen the understanding of organizational identity by exploring how it evolves when the environment changes, when new strategies or different events occur in which identity may face internal or external tensions. Finally, a single in-depth case study is developed exploring the relationships between the identity of an organization and some of its material artifacts.ContributionsThis study has shown that physical objects are part of an identity system that, including other intangible elements, such as verbal communication and narratives, support, instantiate and communicate organizational identity over time. This research results extend the literature on identity, and on the influence and use of material identity objects. The in-depth case study has shown that physical objects has been used to support, instantiate and communicate organizational identity. The data induction process has characterized three different categories of physical objects that provide identity meanings: primal artifacts, identity markers and artifacts created ad hoc.LimitationsThis work provides an exciting opportunity for future research to extend these findings by examining the persistence, change, and materiality of identity in other organizational contexts and industries.
  

DOCTORAL DEGREE IN CHEMICAL PROCESS ENGINEERING

• MUÑOZ NAVARRO, JUAN ANTONIO: Assessing the fire hazard of vegetation at the wildland-urban interface
  
  Author: MUÑOZ NAVARRO, JUAN ANTONIO
  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 CHEMICAL PROCESS ENGINEERING
  Department: Department of Chemical Engineering (EQ)
  Mode: Normal
  Deposit date: 03/05/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: PLANAS CUCHI, EULALIA | PASTOR FERRER, ELSA
  Committee:
       PRESIDENT: OLIVERAS MENOR, IMMACULADA
       SECRETARI: ÁGUEDA COSTAFREDA, ALBA
       VOCAL: DE ALMEIDA, MIGUEL ABRANTES DE FIGUEIREDO BERNARDO
  Thesis abstract: Human population is growing worldwide, so are the places where we live, move and work. These places, like neighbourhoods, networks for transportation of people and materials or industries are frequently near, or even immersed, within forested areas. These areas, where human activity meets with forestlands, are known as the wildland-urban interface. Here, we, our properties and our activities get exposed to forest fires, with a high potential for the loss of human lives and assets. The solution to this problem is complex, comprises various aspects and involves reducing the risk at the wildland-urban interface.One of the main features of this problem is the vegetation, that act as a natural fuel for the fire. Here, the ornamental vegetation has an active role driving the fire within the wildland-urban interface, while the wild vegetation drives the fire front from the forest where the fire ignites to the boundaries of our settlements.The goal of this thesis is to assess the fire hazard at the wildland-urban interface, addressing the problem from the perspective of these natural fuels. To meet this goal, the chapters of this thesis characterize and model the burning behaviour of ornamental and wild vegetation and develop documents, methodologies and tools to implement this knowledge.To characterize ornamental vegetation and the way it burns, this thesis shows detailed fuel samplings, real-scale burning experiments and a forensic study of a real fire in the wildland-urban interface. With this information it was possible to develop custom scripts to simulate ornamental vegetation fires in Fire Dynamics Simulator, which is a Computational Fluid Dynamic simulator specially designed to simulate heat and smoke transportation from the fire.To characterize fires burning wild vegetation, this thesis focuses on the boundaries of the wildland-urban interface and develops models able to predict flame geometry from the environmental conditions, which is necessary to forecast fire impact on the people and the structures. Finally, this thesis presents a software ready to be used by fire managers that uses the information obtained from these models to size the preventive infrastructures that surround our settlements.
  
• NASR ESFAHANI, KOUROSH: Mathematical modeling of advanced oxidation processes for the efficient wastewater treatment: Integrated Management of advanced oxidation processes and conventional Bio-Processes for the removal of recalcitrant components
  
  Author: NASR ESFAHANI, KOUROSH
  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 CHEMICAL PROCESS ENGINEERING
  Department: Department of Chemical Engineering (EQ)
  Mode: Normal
  Deposit date: 28/03/2024
  Reading date: 02/07/2024
  Reading time: 11:00
  Reading place: Sala Polivalent de l'Edifici I, Planta baixa, Campus Diagonal-Besòs
  Thesis director: PEREZ MOYA, MONTSERRAT | GRAELLS SOBRE, MOISES
  Committee:
       PRESIDENT: PAIS VILAR, VÍTOR JORGE
       SECRETARI: SOLER TURU, LLUIS
       VOCAL: GARCIA MONTAÑO, JULIA
  Thesis abstract: The objective of this thesis is to contribute to the development of mathematical modeling of Advanced Oxidation Processes (AOPs) aimed at the competent treatment of recalcitrant organic compounds in wastewater. In particular, the Ph.D. thesis first focuses on developing mathematical models of AOPs, implementing these models in software tools, and enabling a deeper understanding of the complex nature of these processes through the detailed simulation of the evolution of chemical species along the reaction time for diverse and unexplored scenarios. Hence, these tools are next used for fitting the models to the experimental data obtained in the laboratory in the course of the thesis or reported in the literature. The fitted models are analyzed and refined through sensitivity analysis techniques, and finally, they are validated and their accuracy assessed. Models are mainly used for addressing operational issues, but also design aspects are considered in regard of the simulation of integrated processes using AOPs and conventional biotreatment processes.The thesis specifically addresses the development of a model for AOPs, above all photo-Fenton processes, including flexible H2O2 supply given as a function of time. The model contributes a practical tool aimed at providing model-based simulation for solving the problem of the management of the H2O2 dosage profile of the photo-Fenton process.The thesis also addresses the problem of the pH dependency of the photo-Fenton by modeling the possibility of performing the photo-Fenton process at near-neutral pH. This is studied by considering the use of iron complexing agents such as ethylenediamine disuccinic acid (EDDS). In a subsequent stage, as a step forward in improving photo-Fenton processes, a reported kinetic model of the Fe(3+)-EDDS mediated photo-Fenton process is extended to include the reactions occurring in the absence of H2O2, when EDDS(¿ 3- )radical generated from the lysis of the Fe(3+)-EDDS complex is responsible for the organic matter degradation. This is achieved by adopting a novel semi-empirical approach based on lumping radical species.Ozonation of wastewater is also studied as a different case of AOPs, focusing in the modeling of ozone decay during the treatment of secondary effluents containing organic matter. This is addressed by proposing a new model, based again in the used of lumped or surrogate concentrations. The ozone model developed is shown to be capable of describing the complex profile of the ozone at different initial concentrations, and has proved accurate to describe the experimental data obtained in the lab, as well as data reported in the literature.The modeling approach adopted in this thesis has also been used to explore integrated processes combining AOPs with other processes, namely conventional biotreatment processes which main acknowledged limitation is the incapacity to remove recalcitrant compounds from wastewaters. The study combined the AOP models developed with standard models such as ASM1 to map the correspondence between the variables employed in each model, and produce the simulation of different scenarios combining these two technologies.As a final remark, the thesis has also addressed the design and development of chemical reactors, particularly prototypes for photo-Fenton processes using 3D-printing. This last study addresses the selection of materials according to different criteria for reactor prototyping and subsequent testing of the chemical suitability of the reactor for carrying out AOPs.
  

DOCTORAL DEGREE IN CIVIL ENGINEERING

• GÓMEZ DUEÑAS, SANTIAGO: Unraveling Hydrological Dynamics: Climate and Human Implications in the Magdalena River Streamflow and its Interaction with Ciénaga Grande de Santa Marta Wetland
  
  Author: GÓMEZ DUEÑAS, SANTIAGO
  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 CIVIL ENGINEERING
  Department: (DECA)
  Mode: Normal
  Deposit date: 16/04/2024
  Reading date: 14/06/2024
  Reading time: 16:00
  Reading place: Sala Actes, edifici Vèrtex, Campus Nord, Gran Capitan S/N 08034 Barcelona, Spain
  Thesis director: BATEMAN PINZON, ALLEN | SANTOS GRANADOS, GERMÁN RICARDO
  Committee:
       PRESIDENT: SOLÉ, AURELIA
       SECRETARI: DE MEDINA IGLESIAS, VICENTE CÉSAR
       VOCAL: LA ROCCA, MICHELE
  Thesis abstract: This study offers a comprehensive understanding of the hydrological dynamics of the Magdalena River (MR) basin, located in Colombia. Multiple elements that affect streamflow were analyzed, such as climate-forcing drivers and human-induced ones, to understand the complex interactions that shape the region's hydrology.Firstly, the influence of many factors on the flow of water downstream of the Magdalena River was studied. The research identified El Niño southern oscillation (ENSO) episodes as crucial climate-forcing drivers and human-induced modifications such as reservoir evaporation. The complex nature of streamflow changes over time was highlighted by showing the variations in the average, volume, and maximum streamflow, as well as oscillations in evaporation and minimum streamflow, especially during positive ENSO episodes. These findings offer important insights into the changing hydrological regime of the MR basin, emphasizing the complex combination of elements that influence its flow patterns throughout time.Moreover, the study explored the hydrological connection between the MR and the Ciénaga Grande de Santa Marta (CGSM) wetland, revealing the interdependence of these two ecosystems. For this, the study explores the vulnerability of downstream habitats, especially wetlands, to changes in streamflow inputs by taking a broad approach that views the entire wetland as a unified unit. It identified crucial threshold ranges where the inflow from the Magdalena River to the CGSM becomes uncertain. This analysis highlights the urgent need to understand the interactions between water flow and wetland ecosystems and their significant impact. Furthermore, the present research utilizes Long Short-Term Memory (LSTM) neural network models to predict streamflow changes at the Calamar gauging station. The goal was to improve the precision of streamflow predictions by combining data from several gauging stations and reservoir evaporation records. Finally, this study can help enhance the comprehension of the intricate hydrological processes in the MR basin, revealing the interconnected effects of climate fluctuations, human actions, and ecosystem dynamics. In this context, this research sets the foundation for creating well-informed water resource management strategies in Colombia that protect wetland ecosystems' ecological health and adaptability in the face of ongoing environmental changes.
  

DOCTORAL DEGREE IN COMPUTER ARCHITECTURE

• ALBUQUERQUE PORTELLA, FELIPE: A paradigm shift of HPC for geosciences: a novel HPC service model for geosciences applications
  
  Author: ALBUQUERQUE PORTELLA, FELIPE
  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 COMPUTER ARCHITECTURE
  Department: (DAC)
  Mode: Normal
  Deposit date: 25/03/2024
  Reading date: 06/06/2024
  Reading time: 11:00
  Reading place: La defensa es realitzarà a la Sala C6-E106 de la Facultat d'Informàtica de Barcelona al Campus Nord (FIB)
  Thesis director: BERRAL GARCÍA, JOSEP LLUÍS | CARRERA PÉREZ, DAVID
  Committee:
       PRESIDENT: FONTOURA DE GUSMAO CERQUEIRA, RENATO
       SECRETARI: TOUS LIESA, RUBÉN
       VOCAL: DE MORAES, RAFAEL JESUS
  Thesis abstract: The Oil and Gas (O&G) industry ranks prominently among the leading commercial users of powerful supercomputers worldwide, as indicated by global High-Performance Computing (HPC) ranking lists, such as TOP500 and Green500. Geoscience applications, particularly flow and geomechanical simulators, pose demanding workloads for HPC in adressing complex engineering challenges in the O&G industry, together with seismic processing. The rise of hybrid on-demand and cloud HPC environments presents new challenges to end users. Beyond expertise in their fields, users must navigate the intricacies of computer architecture to select the optimal hardware and parallelization option. They also need to consider the business model decisions of the cloud providers, such as managing spot instances, selecting different cloud regions, or even different cloud providers.Furthermore, users struggle with the complexities of configuring their own geoscience software due to the multitude of tunable numerical parameters. Default values may not be optimal for specific reservoir models, requiring geoscientists¿ expertise in both the physics and mathematics behind the simulators and in computer science. A deep understanding of application performance is challenging, as it can vary based on input parameters. Many users end up relying on default configurations or decisions by system administrators for geoscience software, missing opportunities to optimize speed and cost-effectiveness.This thesis aims to shift the paradigm in utilizing HPC for geoscience by entrusting computer architecture decisions to domain-aware optimization algorithms. Such an approach not only enhances usability for the end user, but can also translate into substantial reductions in both time and cost. These algorithms could lead to better utilization of on-premises supercomputers and cost optimization of cloud resources. We evaluate the feasibility of this approach through the contributions of three algorithms. The first algorithm of this work was named TunaOil, which is a novel methodology that uses previous reservoir simulation executions to train an oracle that proposes near-optimal numerical parameters for subsequent simulations within a History Matching (HM) workflow. This allows the simulation parameters to be adjusted without additional executions, saving valuable time. Experiments show that the contribution of this algorithm is an improvement of up to 31% in the overall runtime of the HM workflow.The second algorithm, named MScheduler, is a metascheduler framework designed for reservoir simulations in the cloud. It effi-ciently executes SLURM jobs by utilizing spot Virtual Machines (VMs) to minimize costs and ensure job completion even in the event of VM termination. Key contributions include a novel methodology for reservoir simulation checkpointing, a cost-based scheduler, and an analysis of the strategy using real production jobs. MScheduler significantly reduces financial costs with a slight increase in makespan. On average, it reduces monetary costs by up to 32%, with only an 8% increase in the makespan compared on-demand executions. In the best case, the monetary savings reach 66%, with a 19% increase in makespan.The third algorithm utilizes Machine Learning (ML) algorithms in job schedulers to predict execution times of reservoir job, improving cluster resource efficiency. The developed model classifies the duration time interval of SLURM reservoir simulation jobs with an accuracy of more than 70%, exceeding the standard performance described in the job scheduling literature, thus contributing to improved scheduling decisions.Together, these algorithms mark a paradigm shift in HPC utilization for geoscience applications. They liberate end users from complex computer architecture choices, contributing to improved decision-making and significant time and cost benefits.
  
• FERRIOL GALMÉS, MIQUEL: Network modeling using graph neural networks
  
  Author: FERRIOL GALMÉS, MIQUEL
  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 COMPUTER ARCHITECTURE
  Department: (DAC)
  Mode: Normal
  Deposit date: 10/04/2024
  Reading date: 06/06/2024
  Reading time: 10:30
  Reading place: La defensa es realitzarà a la Sala C6-E101 de la Facultat d'Informàtica de Barcelona al Campus Nord (FIB)
  Thesis director: CABELLOS APARICIO, ALBERTO | BARLET ROS, PERE
  Committee:
       PRESIDENT: PESCAPÈ, ANTONIO
       SECRETARI: ARIAS VICENTE, MARTA
       VOCAL: RÉTVÁRI, GÁBOR
  Thesis abstract: Network modeling is central to the field of computer networks. Models are useful in researching new protocols and mechanisms, allowing administrators to estimate their performance before their actual deployment in production networks. Network models also help to find optimal network configurations, without the need to test them in production networks. Arguably, the most prevalent way to build these network models is through the use of discrete event simulation (DES) methodologies which provide excellent accuracy. State-of-the-art network simulators include a wide range of network, transport, and routing protocols, and are able to simulate realistic scenarios. However, this comes at a very high computational cost that depends linearly on the number of packets being simulated. As a result, they are impractical in scenarios with realistic traffic volumes or large topologies. In addition, and because they are computationally expensive, they do not work well in real-time scenarios.Another network modeling alternative is Queuing Theory (QT) where networks are represented as inter-connected queues that are evaluated analytically. While QT solves the main limitation of DES, it imposes strong assumptions on the packet arrival process, which typically do not hold in real networks.In this context, Machine Learning (ML) has recently emerged as a practical solution to achieve data-driven models that can learn complex traffic models while being extremely accurate and fast. More specifically, Graph Neural Networks (GNNs) have emerged as an excellent tool for modeling graph-structured data showing outstanding accuracy when applied to computer networks. However, some challenges still persist:1. Queues and Scheduling Policies: Modeling queues, scheduling policies, and Quality-of-Service (QoS) mappings within GNN architectures poses another challenge, as these elements are fundamental to network behavior.2. Traffic Models: Accurately modeling realistic traffic patterns, which exhibit strong autocorrelation and heavy tails, remains a challenge for GNN-based solutions.3. Training and Generalization: ML models, including GNNs, require representative training data that covers diverse network operational scenarios. Creating such datasets from real production networks is unfeasible, necessitating controlled testbeds. The challenge lies in designing GNNs capable of accurate estimation in unseen networks, encompassing different topologies, traffic, and configurations.4. Generalization to Larger Networks: Real-world networks are often significantly larger than testbeds. Scaling GNNs to handle networks with hundreds or thousands of nodes is a pressing challenge, one that requires leveraging domain-specific network knowledge and novel architectural approaches.This dissertation represents a step forward in harnessing Graph Neural Networks (GNN models) for network modeling, by proposing a new GNN-based architecture with a focus on addressing these critical challenges while being fast and accurate.
  
• JOSEPH, DIYA: Improving memory access efficiency for real-time rendering in tile-based GPU architectures
  
  Author: JOSEPH, DIYA
  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 COMPUTER ARCHITECTURE
  Department: (DAC)
  Mode: Normal
  Deposit date: 30/04/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: GONZÁLEZ COLÁS, ANTONIO MARIA | ARAGÓN ALCARAZ, JUAN LUIS
  Committee:
       PRESIDENT: XEKALAKIS, POLYCHRONIS
       SECRETARI: JIMENEZ GONZALEZ, DANIEL
       VOCAL: DE LUCAS CASAMAYOR, ENRIQUE
  Thesis abstract: Following the growing demands of applications mobile GPUs have greatly evolved in the past decade with expectations for continued advancement. These developments must address the rising performance demands and prioritize energy efficiency to accommodate the energy and temperature constraints of battery-powered, handheld devices. Main memory accesses are one of the main sources of energy consumption and occasionally a source of performance bottleneck in GPUs. The adoption of Tile-Based Rendering (TBR) architecture for many mobile GPUs in the late 1990s, marks a leap towards energy efficiency for mobile GPUs by enhancing locality and minimizing bandwidth-intensive memory accesses.The objective of this thesis is to enhance memory access efficiency in TBR GPU architectures for graphics applications. The strategy involves fine-tuning the structures in the memory hierarchy or altering the memory access patterns directed towards the memory hierarchy. By capitalizing on the unique characteristics of graphics applications, the goal is to boost both performance and energy efficiency with minimal hardware adjustments, thereby avoiding any adverse impact on general-purpose workloads running on GPUs.TBR architectures introduce an overhead through the creation of a specialized data structure for tiling which is stored in memory and cached in L1 and shared L2 caches. The OPT replacement policy, has been formally proven as optimal for minimizing misses but it is near-impossible to implement in hardware. The first proposal in this thesis brings the OPT to life, for this data structure. Along with other improvements in the L2, this proposal called TCOR results in a 13.8% decrease in the memory hierarchy energy consumption and an increased throughput in the Tiling Engine. DTexL, the second proposal in this thesis, increases the aggregated capacity of certain L1 caches by reducing replication of memory blocks. Contemporary GPUs have multiple GPU cores and a scheduler that distributes work (warps) among them, focusing on load balancing. These load balancing techniques are detrimental to texture memory locality in the L1 caches. We propose a new workload scheduler that favours texture locality and to overcome the resulting load imbalance, we propose a minor modification to the GPU architecture. DTexL results in a 46.8% decrease in L2 Accesses, a 19.3% increase in performance and a 6.3% decrease in total GPU energy. All this with a negligible overhead.Literature is plentiful in works exploiting cache locality for GPUs. A majority of them explore replacement or bypassing policies. In our third proposal, we surpass this exploration by fabricating a formal proof for a no-overhead quasi-optimal caching technique in the shared L2 for textures. We exploit the frame-to-frame reuse of textures by traversing frames in a boustrophedonic manner w.r.t. the conventional frame-to-frame tile order. We first approximate the texture access trace to a circular trace and then forge a formal proof for our proposal being optimal for such traces. We call our proposal Boustrophedonic Frames.Hiding memory latency is becoming a problem in contemporary GPUs. To address this challenge, we introduce WaSP as the final work in this thesis, a lightweight warp scheduler tailored for GPUs in graphics applications. WaSP strategically mimics prefetching by initiating a select subset of warps, termed priority warps, early in execution to reduce memory latency for subsequent warps. WaSP reduces average memory latency while maintaining locality for the majority of warps. While maximizing memory parallelism utilization, WaSP prevents saturating the caches with misses to avoid filling up the MSHRs. This approach reduces cache stalls that halt further accesses to the cache. Overall, WaSP yields a 3.9% performance speedup with a negligible overhead.
  

DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING

• JATIVA GUZMAN, ANDRES: APLICABILIDAD DE LA CENIZA VOLCÁNICA DE BAJA ACTIVIDAD COMO NUEVO RECURSO PARA MATERIALES CEMENTICIOS SOSTENIBLES.
  
  Author: JATIVA GUZMAN, ANDRES
  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 CONSTRUCTION ENGINEERING
  Department: (DECA)
  Mode: Normal
  Deposit date: 03/04/2024
  Reading date: 29/05/2024
  Reading time: 11:00
  Reading place: Sala C1002 Edifici C1, Escola de Camins (ETSECCPB)- Campus Nord 08034 Barcelona
  Thesis director: ETXEBERRIA LARRAÑAGA, MIREN
  Committee:
       PRESIDENT: MAURY RAMIREZ, ANIBAL CESAR
       SECRETARI: CASANOVA HORMAECHEA, IGNACIO
       VOCAL: GIRÓ PALOMA, JESSICA
  Thesis abstract: Volcanic ash (VA), abundantly available in various regions globally, serves as an effective supplementary cementitious material (SCM) for partially substituting Portland cement (OPC). However, its inherently low reactivity presents a challenge for its broader utilization. This challenge can be overcome by enhancing VA's reactivity via several approaches: 1) employing mechanical and thermal treatments; 2) adding alkali activators; 3) using corrective additives to balance VA's chemical shortcomings; and 4) applying appropriate curing methods to stimulate pozzolanic reactions.According to ASTM C618 standards, VA falls into the Class N category. The study explored various activation strategies, including VA calcination (CVA) at temperatures ranging from 500 to 900 °C, alkali activation using Na2SiO3 (NSi), CaCl2 (CaCl), Na2SO4 (NS), and Na2CO3 (NC) at 1 to 4% dosages (relative to binder weight), and the strategic inclusion of SCMs like lime (L), fly ash (FA), and slag (EC) in amounts of 10, 20, and 30% (relative to VA weight). The curing process's influence was examined under different conditions: moist and heated environments (40 and 70°C for 3 days). The best mortar mixes underwent evaluations for compressive strength at intervals of 7, 28, and 90 days, alongside assessments of physical characteristics (e.g., porosity, water absorption, density) and microstructural properties. The mortars' durability was further gauged through shrinkage and acid resistance tests (against HCl, H2SO4, HNO3).For mortars comprising 35% VA (VA35) and subjected to moist curing, calcining VA at 700 °C coupled with a 20% lime addition resulted in achieving mortars boasting a peak strength of 49 MPa at 28 days, alongside a 9% reduction in water absorption compared to mortars with unmodified VA (VA35). Similarly, employing alkali activators, particularly NSi and CaCl at 1% and 2% dosages respectively, led to mortars demonstrating superior mechanical and physical properties.In mortars with a 50% VA content, the optimal alkali activator dosages were identified as 2% for NSi and 1% for CaCl. The addition of 20% FA and 10% EC emerged as the most effective corrective additives. Thermal curing (70°C for 3 days) significantly boosted early strength gains, curtailed mortar shrinkage, and enhanced resistance to H2SO4, especially notable in mortars prepared with CVA and 1% CaCl. Notwithstanding, at the 90-day mark, moist chamber curing was found to facilitate greater strength increases. A specific mix utilizing mixed activation (1% CaCl with CVA and 10% EC) notably outperformed, achieving 56 MPa, which is a 32% improvement over mortars with untreated VA (VA50). The presence of hydrated phases (C-S-H/C-S-A-H) and minerals such as portlandite, strätlingite, kuzelite, and Friedel's salt attested to the mortars' commendable performance.For mortars containing 75% VA, the best results were achieved with 2% NSi and 1% CaCl as activators, and the addition of 10% FA and 10% EC as correctives additives. Under moist curing, a mixed-activated mortar (1% CaCl-CVA-10%EC) exhibited the highest compressive strength at 90 days, reaching 44 MPa¿a 29% increase over mortars with untreated VA (VA75). Thermal curing expedited early strength development, minimized shrinkage, and bolstered resistance to H2SO4, along with improving porosity and water absorption rates, with the exception of CaCl-containing mortars. Notably, the VA75 mix showed limited portlandite formation and an absence of strätlingite.This investigation confirms the feasibility of achieving satisfactory compressive strengths in mortars with high VA content. Furthermore, by leveraging the studied activation and curing techniques, it's possible to tailor the mortar mix for specific applications, optimizing for properties such as minimal shrinkage, reduced water absorption, enhanced early-age strength, or heightened resistance to particular acid exposures.
  
• LIPA CUSI, LEONEL: Metodología numérica automatizada para la evaluación de la respuesta dinámica de construcciones prehispánicas de piedra de junta seca en el Perú.
  
  Author: LIPA CUSI, LEONEL
  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 CONSTRUCTION ENGINEERING
  Department: (DECA)
  Mode: Change of supervisor
  Deposit date: 03/04/2024
  Reading date: 20/05/2024
  Reading time: 16:00
  Reading place: Aula N-201, edificio Mac Gregor Pontificia Universidad Católica Perú(PUCP)- 9:00h (Lima). Zoom:https://pucp.zoom.us/j/94161428415?pwd=YzZrSUQza01NQWkwY1R5UEg2MlZIdz09
  Thesis director: PELA, LUCA | TARQUE, SABINO NICOLA
  Committee:
       PRESIDENT: GOICOLEA RUIGÓMEZ, JOSÉ MARÍA
       SECRETARI: ROCA FABREGAT, PEDRO
       VOCAL NO PRESENCIAL: SALOUSTROS, SAVVAS
       VOCAL NO PRESENCIAL: SANTA CRUZ HIDALGO, SANDRA CECILIA
       VOCAL NO PRESENCIAL: SANDOVAL MANDUJANO, CRISTIAN
  Thesis abstract: The study and the conservation of stone heritage is a global concern, mainly when these constructions are in seismic zones. Due to its great cultural and historical diversity, Peru has many stone constructions in different archaeological sites, covering different construction typologies. Unfortunately, many of these constructions have not yet been structurally evaluated, so their structural behaviour is unknown. In addition, there is no classification of the stone structural typologies (taxonomy), so the different characteristics of existing constructions are unknown. One way to study the non-linear dynamic behaviour of these stone structures is to use a rigorous -but fast- numerical methodology to adequately reproduce the different failure mechanisms based on the dynamics of rigid bodies within the finite element method.Then, this work presents a taxonomic classification of prehispanic stone constructions in Peru, derived from a field study, as the first contribution. Based on this taxonomy, several archaeological sites in Puno and Cusco were classified, and the most common typologies of these regions were identified. The research also proposes novel algorithms developed in Python to obtain the geometric model of dry-joint stone structures using images taken by a camera, a mobile phone, or an existing photograph (including identification of stones and joints, named image segmentation). These routines allow the creation of a 3D model of each block (stone), assembling them, and exporting them to a finite element program for further evaluation.Regarding developing a numerical methodology, the dynamic of rigid bodies within the finite element method is proposed here. Each stone block is considered a rigid body interconnected with other blocks through nonlinear interfaces. This methodology was validated using Abaqus, based on the results of experimental tests developed in this thesis. The experimental campaign was carried out on three walls built with concrete blocks, simulating the geometry of the Inca structures. The walls were built on a tilting table and tested by rotating them out of the plane of the wall. Then, numerical models of the tests were developed by considering each stone as a rigid body and calibrating the contact properties to simulate the experimental behaviour correctly. The numerical results in weight, collapse angle, relative displacements at different points of the structure and collapse mechanisms were very similar to those obtained in the experimental campaign.As a case study, a section of an Inca stone wall from Sacsayhuaman, Cusco, was numerically evaluated using various seismic records. The complete geometric model of the stone wall was automatically obtained using the Python routines. Furthermore, discrete element particles represented the soil behind the wall. The properties of the numerical model were obtained from the experimental campaign, and the predominant frequencies of the structure were obtained using the vibration approach. As a result, the structure can adequately support these seismic records scaled up to a peak acceleration of 0.1 g. However, it suffers significant residual displacements for scaled records greater than 0.2 g.The proposed numerical methodology allows the rigorous evaluation of dry-jointed stone structures, knowing if the structure should be intervened to ensure its functionality. Therefore, it is expected that the results of this research will be used to study other stone constructions, opening possibilities for improving the methodology for different structural configurations.
  

DOCTORAL DEGREE IN ELECTRICAL ENGINEERING

• ORELLANA MONTAÑO, LUIS CARLOS: Stability studies of multi-infeed grid-connected VSCs
  
  Author: ORELLANA MONTAÑO, LUIS CARLOS
  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 ELECTRICAL ENGINEERING
  Department: (DEE)
  Mode: Normal
  Deposit date: 03/05/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: SAINZ SAPERA, LUIS | PRIETO ARAUJO, EDUARDO
  Committee:
       PRESIDENT: BONGIORNO, MASSIMO
       SECRETARI: EGEA ÁLVAREZ, AGUSTÍ
       VOCAL: BEERTEN, JEF JAN J.
  Thesis abstract: There is a global effort to reduce the emission of greenhouse gases to mitigate the consequences of climate change. The decarbonisation of the electricty sector is already underway to meet this goal. A new energy mix driven by solar and wind energy resources are set to dominate the global capacity additions. These resources are typically connected to the AC grid by means of power converters, identified as key enablers for the rapid expansion of renewable energies and the transmission system development.Modern power systems are growing in complexity, characterised by the dominance of power electronics such as VSC technology. However, VSCs also bring new challenges due to the oscillatory phenomena caused by the interaction between their control and the grid. These oscillations can lead to instabilities, specially in poorly damped networks as reported in the literature. The knowledge of VSCs control structures is not always known due to the intellectual property protection over the controllers development. Studying their dynamic behaviour and possible impact over the network is becoming a more challenging task.It is desirable to have test facilities closer to reality to study these complex systems; however, it may not be feasible due to the high cost and risks involved. This can be addressed by performing offline computer¿based EMT simulations of white and black¿box models. Nevertheless, this can be a long and arduous task without adequate methods which enable to evaluate the system stability and identify the major players that might affect it. The development of frequency domain methods are currently of great interest as they can use frequency impedance curves obtained from impedance measurements of black¿box models or real equipment. However, this approach alone might not provide all the necessary insights to understand the power system's complexity. This can be complemented with real¿time simulations, where simulation and physical hardware are combined. One advantage is that hardware which cannot be included in a laboratory setup for practical limitations can be simulated instead.This document addresses these problems, making an emphasis on the development of methodologies which adapt to the current context and simplify the study the stability of modern power systems, both for offline and real¿time studies. The methodologies developed are evaluated in the frequency domain and allow to study the oscillatory phenomena in poorly damped systems
  

DOCTORAL DEGREE IN ENVIRONMENTAL ENGINEERING

• KILIÇ, EYLEM: Advancing the use of waste streams in plastic composites
  
  Author: KILIÇ, EYLEM
  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 ENVIRONMENTAL ENGINEERING
  Department: (DECA)
  Mode: Article-based thesis
  Deposit date: 18/03/2024
  Reading date: 30/05/2024
  Reading time: 12:00
  Reading place: Place: ETSECCPB UPC, Campus Nord Building C1. Classroom: 002 C/Jordi Girona, 1-3 08034 Barcelona
  Thesis director: PUIG VIDAL, RITA | FULLANA PALMER, PERE
  Committee:
       PRESIDENT: MÉNDEZ GONZÁLEZ, JOSÉ ALBERTO
       SECRETARI: GASSO DOMINGO, SANTIAGO
       VOCAL NO PRESENCIAL: EL BACHAWATI, MAKRAM
  Thesis abstract: The leather industry faces global challenges related to its sustainability credentials due the significant waste generated throughout the leather production processes. In the context of contemporary environmental policy, which is increasingly focused on sustainable production and consumption, the need to understand and mitigate environmental impacts associated with leather has become a strategic and economic imperative. In this respect, a comprehensive "gate-to-gate" life cycle assessment (LCA) was conducted following the newly released Leather Product Environmental Footprint Category Rules (PEFCR). The analysis aimed to evaluate the environmental impacts of leather production, with a specific focus on New Zealand's leather production industry, mainly due to its agriculturally oriented economy and large size of livestock sector.This thesis builds upon this foundation by addressing the issue of solid waste in the leather industry. Therefore, a waste valorization strategy was investigated to convert unavoidable waste into valuable resources through the production of new, value added composites, which involves incorporating leather waste (BF) into virgin and recycled high-density polyethylene (HDPE). The focus of this thesis is to analyze environmental impact of these novel composites, to improve the implementation of circular economy principles, within the context of their use in automotive bumper production. The environmental impact of these novel composites was compared to conventional polypropylene (PP), bumpers, by performing a cradle-to-gate life cycle assessment (LCA). The thesis also aims to provide a contribution to LCA methodology applied to composite materials, by adopting various functional units, such as mass, volume, and the volume of raw material fulfilling a specific impact strength requirement.The in-depth analysis of mechanical and thermal properties of the BF/HDPE composites highlights the composite¿s potential for industrial applications that require high mechanical strength and low thermal conductivity. The incorporation of leather waste not only enhances material properties, but also contributes to environmental sustainability by converting unavoidable waste into a value added product. The environmental assessment, adopting a cradle-to-gate LCA with various functional units, indicates that composites made from recycled HDPE and leather waste have a lower environmental impact than those from virgin materials. The only exception is when the material's impact strength is a key factor in the functional unit, due to the higher impact strength of HDPE-BF composites. In all cases, increasing the content of recycled materials in the bumpers increases its environmental performance, supporting the advancement of circular economy principles in the automotive sector.The research highlights the significance of choosing an appropriate functional unit, based on specific applications such as automotive bumpers, in comparing the environmental footprint of innovative composite materials with that of traditional materials. Broadening the scope of evaluation to include various functions yields a more realistic scenario, but it leads to higher uncertainties in the results as well.
  

DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING

• BISCARO, CATERINA: 3D FEM meso-level analysis of sulphate attack in concrete: new results and developments using parallel HP computing
  
  Author: BISCARO, CATERINA
  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 GEOTECHNICAL ENGINEERING
  Department: (DECA)
  Mode: Change of supervisor
  Deposit date: 16/04/2024
  Reading date: 07/06/2024
  Reading time: 12:00
  Reading place: Sala Donghi, Dipartimento ICEA, via Marzolo 9, Padova
  Thesis director: CAROL VILARASAU, IGNACIO | XOTTA, GIOVANNA
  Committee:
       PRESIDENT: SALOMONI, VALENTINA
       SECRETARI: PRAT CATALAN, PERE
       VOCAL: LIAUDAT, JOAQUÍN
       VOCAL: CIANCIO, DANIELA
       VOCAL: MAROTTI DE SCIARRA, FRANCESCO
  Thesis abstract: When concrete is subject to an environment characterised by a high humidity index and rich in sulphate ions, a concrete degradation process may be initiated due to External Sulphate Attack (ESA). The sulphate penetrating into the concrete activates a series of chemical reactions that lead to the formation of secondary ettringite, which may cause non-uniform volumetric expansions that may in turn generate cracking and ultimately culminate in the disintegration of the sample. Because the cracking may in turn facilitate sulphate penetration, ESA may be considered a coupled chemical-mechanical problem. In this study, the numerical analysis of ESA is conducted using the Finite Element Method by considering the specimen at the meso-level composed of larger aggregates embedded in a mortar matrix. Standard continuum finite elements are used to discretise the aggregates and the mortar. Zero-thickness interface elements are inserted along all the aggregate-mortar and selected mortar-mortar contacts to represent potential cracks. The diffusion-reaction of sulphate ions (chemical problem) is formulated following Tixier and Mobasher (2003) and Idiart et al. (2011b). Regarding the mechanical problem, the continuum elements are considered linear elastic, while the interface elements behave according to an elasto-plastic law incorporating concepts of fracture mechanics which was initially developed by Carol et al. (1997) and later extended for 3D analysis by Caballero et al. (2006).The first part of this thesis deals with the verification and use of DRAC5, a completely parallelised version of the in-house code developed within the materials mechanics group (MECMAT) of the Universitat Politècnica de Catalunya (UPC) which now incorporates MPI and PETSC libraries as well as HDF5 i/o files. This new version of the code, which is used to solve both the mechanical problem and the chemical problem through a staggered scheme, has allowed the analysis of new and more challenging 3D studies, producing realistic results that reflect the 'onion peeling' cracking pattern, similar to what has been observed in the laboratory and in previously studied 2D cases (Idiart, 2009). The second part of the thesis, deals with the development of new numerical solving techniques applicable to this type of mesh. In particular, a solution technique based on substructuring and the Schur complement is applied to the analysis of specimens comprising elements of the continuum exhibiting linear elastic behaviour and interface elements characterised by non-linear (elasto-plastic) behaviour. This new technique, which reduces substantially the number of degrees of freedom that need to be considered during the iterative process, has been preliminarily implemented in DRAC4, a simpler series version of the code, and is tested showing great advantages in terms of solution time for a range of 2D application examples. The development of a new formulation using rigid-plastic interfaces is also initiated. This formulation uses relative degrees of freedom at each pair of interface nodes, and leads to the resolution of a Linear Complementarity Problem. This development allows a further reduction in the degrees of freedom of the problem by only considering the nodes of the interface elements involved in the fracture process.
  

DOCTORAL DEGREE IN MARINE SCIENCES

• ASTUDILLO GUTIERREZ, CARLOS SALVADOR: Posidonia oceanica: A Perspective From Coastal Protection
  
  Author: ASTUDILLO GUTIERREZ, CARLOS SALVADOR
  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: (DECA)
  Mode: Article-based thesis
  Deposit date: 23/04/2024
  Reading date: 26/06/2024
  Reading time: 11:00
  Reading place: Edifici C1 Aula 002, ETSECCPB, Campus nord, Universitat Politècnica de Catalunya
  Thesis director: GRACIA GARCIA, VICENTE | CACERES RABIONET, IVAN
  Committee:
       PRESIDENT: COLOMER FELIU, JORDI
       SECRETARI: GIRONELLA I COBOS, FRANCESC XAVIER
       VOCAL: FERNÁNDEZ MORA, MARIA DE LOS ANGELES
  Thesis abstract: Over the decades, the global coastlines have been a key indicator of the development of actual societies. However, the cost of this growth has resulted in the depredation of natural environments. The increased frequency of storms, rising temperatures or rising sea levels are clear symptoms that the environment is responding to the increased pressure that the coasts have been subjected to. In recent years, the degradation of coastal habitats has accelerated, indicating that traditional engineering solutions alone will not be able to solve the problem in the long term. IThis approach enables nature to be reintroduced as a potential element capable of confronting and counteracting the adverse changes that the coastal landscape is undergoing. In order to achieve this goal, it is essential to conduct a comprehensive analysis of the natural elements that comprise the coastline, with a particular focus on identifying strategies that enhance environmental stability. This study aims to gain a deeper understanding of the impact of Posidonia oceanica seagrass meadows on the coastline, both in their submerged and emerged states.A novel experiment was conducted in the experimental flume CIEM of the LIM/UPC Barcelona. The objective was to evaluate the protective effect of submerged meadows against irregular erosive waves on a sandy beach with a 1:15 slope. A real meadow model was used with plastic substitutes carefully selected to accurately reflect the dimensions, movements and habitats of a real Posidonia oceanica plant. The submergence ratio and density of the meadow were kept constant. The work has focused on measuring the attenuation of wave height, changes in velocity, involvement in sediment transport and shore erosion. The results showed a persistent decrease in wave height from the area behind the meadow to the breaker zone, which was directly correlated with meadow length and wave energy. Consequently, there was less shoreline erosion as a function of wave height attenuation in cases where meadow was present, and even less when the meadow was longer. Behind the longer meadow, there was a notable change in velocity, resulting in an imbalance of peak velocities. This included a decrease in negative peak velocities and an increase in positive peak velocities. This resulted in an increase in the skewness value of the velocity in this area. The orbital velocities exhibited a decrease only for the long meadow case, which contributed to a decrease in sediment transport volume and the formation of a breaker bar closer to the coast.The emerged part of the meadows was evaluated through field work, analysing the accumulations on the shoreline. Several routes were taken along the southern Catalan coast in order to identify the most frequent accumulation sectors associated with the position of the submerged meadow. Areas with seagrass meadows were identified at depths greater than 5 m, and it was found that these areas exhibited a low frequency of occurrence of banquette events. Information on the management of the accumulations was obtained through interviews with the relevant personnel in each coastal municipality. The aim was to ascertain the manner in which the banquette is dealt with during periods of high tourism demand. Furthermore, this work presents a characterisation of parameters such as penetration resistance and permeability of the accumulations. Additionally, a methodology based on thermal oxidation has been presented to accurately quantify the amount of sediment that can accumulate in the banquettes. The results indicate that the banquettes situated in close proximity to the shoreline accumulated less sediment than those positioned at a greater distance from the coast.
  
• MASDEU NAVARRO, MARTA: Distribution and cycling of volatile organic compounds in a tropical coral reef and the adjacent ocean.
  
  Author: MASDEU NAVARRO, MARTA
  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: (DECA)
  Mode: Article-based thesis
  Deposit date: 24/04/2024
  Reading date: 28/05/2024
  Reading time: 11:00
  Reading place: Sala d'Actes Ramon Margalef de l'Institut de Ciències del Mar (Passeig Marítim de la Barceloneta 37-49, 08003, Barcelona).
  Thesis director: SIMÓ MARTORELL, RAFAEL
  Committee:
       PRESIDENT: RIBES LLORDES, MARTA
       SECRETARI: DEL CAMPO GARCIA-RAMOS, JAVIER
       VOCAL: LLUSIÀ BENET, JOAN
  Thesis abstract: Volatile organic compounds (VOCs) participate in ecologycal interactions and climate. In recent years it has been shown that coral reefs are producers of VOCs, but the entire collection of volatiles and the formation processes of many of these compounds within the reef remain to be described, as well as whether these processes are essentially biological (pelagic and benthic) or abiotic (driven by solar radiation and water temperature). To this aim, in this thesis we have studied the VOCs in the internal and external waters of the Mo'orea coral reef, in French Polynesia. This is a well-preserved reef, which is characterized by a virtual unidirectional flow of water and with strong currents, so that it allows to study the connection between the incoming waters, from the open ocean, and the inland waters, influenced by the components and processes of the reef.We have described the spatial and temporal variability of a series of VOCs with climate interest (COS, CS2, isoprene, iodometans (CH3I and CH2ClI), bromometans (CHBr3 and CH2BR2) and DMS), and non-volatile related compounds, such as dimethillefoniopropidated (DMSP), acrylate and dimethylphoxide (DMSO), within lagoon waters and nearby ocean waters. We also made comparisons with concurrent measurements of sea surface temperature, solar radiation, biogeochemical variables (nutrients, organic matter) and the taxonomic abundances and affiliations of the microbial microbial plankton in order to explain the interconnections between DMSP-derived compounds(DMSPC), VOCs and their environment through day/night cycles.The concentration of all the studied VOCs increased when water crossed the reef crest, with the bromomethans being the compounds that showed a greater increase. Incubation experiments with inner-reef waters around midday indicated that (a) photochemical reactions were the main source of COS and the main sink of DMS;(b) microbial plankton was the main source of DMS, isoprene and CH3I, and a major sink of COS;(c) algae were the main source of the polyhalomethanes CH2ClI, CHBr3 and CH2Br2; (d) carbonate sediments were a major source of CS2 and CH2ClI, DMS and isoprene, and the main COS loss. The dominant coral holobiont (Pocillopora sp.) was a source of only DMS and COS. Another studied coral (Acropora pulchra) was an important source of DMSPC, whose concentration near the polyps was parallel to the intensity of sunlight, with large increases during the day and decreases at night. This variation was probably generated by (i) the role of DMSPC as antioxidants for endosymbiotic Symbiodinoceae and for the coral itself, and (ii) the expulsion of endosymbionts under very high solar radiation intensities, as suggested by the molecular description of the microbial community. The identification and quantification of functional genes by metagenomics indicated that the bacteria near the A. pulchra colony were well prepared for the use and transformation of the DMSPC released by coral holobiont. Furthermore, the detailed study of the short-distance gradients of VOCs concentrations between the branches of A. pulchra illustrated the hydrographic complexity that occurs within a branched coral colony.In the deep, transparent and oligotrophic waters os the adjacent open ocean, VOCs were basically originated in planktonic activity but mainly regulated by light, with great importance of photochemical reactions that produced some compounds and destroyed others.In general, for a month, the reef was a net producer and net emitter of VOCs, compared to the open ocean. Using the most enriched VOCs in the reef, as well as nitrate and terrigenous dissolved organic matter, as tracers of reef waters that leave through the outflow channel, we estimated that 35% of the water that enters the reef across the crest is recirculated water of the same reef. This thesis advances our understanding about the production and cycling of VOCs in a tropical coral reef and its relationship with solar radiation.
  

DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING

• MARTIN SAINT-LAURENCE, PABLO: Constitutive modeling of ultrafine-grained refractory high-entropy alloys obtained by powder metallurgy
  
  Author: MARTIN SAINT-LAURENCE, PABLO
  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: (CEM)
  Mode: Normal
  Deposit date: 17/04/2024
  Reading date: 28/05/2024
  Reading time: 11:30
  Reading place: EEBE (Escola d'Enginyeria Barcelona Est) Sala Polivalent de l'Edifici A, Edifici A, planta baixa, Campus Diagonal-Besòs
  Thesis director: CABRERA MARRERO, JOSE MARIA
  Committee:
       PRESIDENT: TORRALBA CASTELLÓ, JOSE MANUEL
       SECRETARI: LLORCA ISERN, NURIA
       VOCAL: CARREÑO GOROSTIAGA, FERNANDO
  Thesis abstract: Refractory high-entropy alloys (RHEAs) prepared by mechanical alloying followed by spark plasma sintering usually outweigh the high-temperature mechanical behavior of as-cast counterpart alloys. Despite that, few studies have been conducted in order to understand their deformation mechanisms associated with these alloys and their particular microstructures (ultrafine grain size and considerable presence of secondary phases). The present work reports the synthesis, the microstructural characterization, and the constitutive modeling the AlCrxFeMoNbTiV2 (x = 0.15, 0.4, 0.8) RHEAs prepared by powder metallurgy, aiming to contribute to the comprehension of the deformation mechanisms behind the high-temperature mechanical behavior of RHEAs obtained with this fabrication route, as well as of the composition-microstructure-properties of RHEAs.In order to do so, the study was divided into three parts. In the first one, the effect of composition and milling time over themicrostructural and particle evolution of the powder was investigated. In the second part, the effect of Cr content and of a heat treatment over phase formation, microstructure, and grain size was investigated. In the third part, the samples were subjected to compression testing between 950 °C and 1100 °C and between 0.0005 s-1 and 0.01 s-1 to obtain the constitutive equations of the peak stress. Additionally, the microstructure of some of the deformed samples was characterized to find microstructural hints associated with the different potential softening and deformation mechanisms. During the milling study, it was observed that most of the changes occurred during the firsts 50 h, resulting in an average particle size of 7 µm and a nanostructured bcc+hcp microstructure. Except for Mo, none of the constituent elements considerably affected the microstructure or the particle size of the milled powders. The as-sintered samples, fabricated using powder milled for 50 h, successfully presented an ultrafine-grained and multiphase microstructure, constituted by a V,Mo-rich bcc matrix, accompanied by Fe,Nb-rich Laves phases, Al2O3 particles, and Ti,Nb-rich carbides. For reference, a hardness of 1124 HV0.3 was obtained in the as-sintered samples. The average grain size of the matrix phase decreased from 0.40 µm to 0.21 µm with further Cr content; however, the high-temperature mechanical properties were not affected. On the other hand, after the heat treatment, the average grain size increased up to 1.5 µm without affecting the phase equilibrium though. In opposition to the Cr content, the heat treatment enhanced the yield strength in a considerable manner: a specific yield strength of 98 MPa·g-1·cm3 at 1000 °C was obtained in these samples, three times that of the as-sintered sample. Regarding the constitutive modeling, the power law excellently fitted the experimental data, resulting in an exponent of 2.45, indicating that grain boundary sliding governed the high-temperature deformation of the studied alloy, just as it does in ultrafine-grained size traditional alloys. Additionally, an elevated activation energy of 527 kJ·mol-1 was obtained, associated either with a high softening resistance as well as with the considerable presence of secondary phases. In the case of the heat-treated samples, dislocation climbing and glide seemed to govern the deformation (at least at 1000 °C), explaining the enhanced strength, attributed to the hindered grain boundary mobility due to the larger grain size.
  

DOCTORAL DEGREE IN MECHANICAL, FLUIDS AND AEROSPACE ENGINEERING

• CHEN, JIAN: EFFECTS OF CAVITATION ON THE WAKE CHARACTERISTICS BEHIND BLUNT TRAILING EDGE HYDROFOILS
  
  Author: CHEN, JIAN
  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 MECHANICAL, FLUIDS AND AEROSPACE ENGINEERING
  Department: Department of Fluid Mechanics (MF)
  Mode: Normal
  Deposit date: 22/04/2024
  Reading date: 06/06/2024
  Reading time: 10:00
  Reading place: Aula del Laboratori d'Hidràulica del Departament de Mecànica de Fluids, pavelló D de l'ETSEIB (ESCOLA TÈCNICA SUPERIOR D'ENGINYERIA INDUSTRIAL DE BARCELONA) Avda. Diagonal, 647, 08028 Barcelona
  Thesis director: ESCALER PUIGORIOL, FRANCESC XAVIER
  Committee:
       PRESIDENT: HIDALGO DÍAZ, VICTOR HUGO
       SECRETARI: CASTILLA LOPEZ, ROBERTO
       VOCAL: ZHANG, DESHENG
  Thesis abstract: The recent developments in hydraulic machinery will increase the possibility of damage resulting from cavitation and/or vortex-induced vibrations. Yet, many researchers have shed light on the vortex street flow and the associated vortex-induced vibration in cavitating-free regimes, but less attention has been paid to the presence of cavitation. In the present study, the effects of cavitation on the vortex street flow behind a blunt trailing edge hydrofoil and its interaction with the vortex-induced vibration have been investigated. This will help to understand the mechanisms involved and to predict the dynamic of vortex-induced vibration with the presence of cavitation, allowing further control of this complex phenomenon in hydraulic machinery and systems.Thus, numerical solvers have been developed that are capable of accounting for the cavitating vortex street flow behind bluff bodies which have been validated and verified using some benchmark cases. Then, the effects of the fluid compressibility in the vortex street flow behind the wedge have been determined. Moreover, a series of numerical studies on cavitating vortex street flow behind a blunt trailing edge hydrofoil NACA 0009 have been conducted by predicting the boundary layer transition. As a result, the effects of cavitation on flow dynamics and its interaction with vortex-induced vibration have been examined.The impacts of fluid compressibility on the dynamics of the cavitating wake flow have been found to depend on the frequency range. At low frequencies, the effects of fluid compressibility are minimal and can be disregarded. On the other hand, fluid compressibility has been observed to amplify spectral energy at high frequencies. Interestingly, it has been found that almost identical numerical results with and without fluid compressibility are obtained in terms of predicted mean pressure profiles, dominant vortex shedding frequencies, and instantaneous and mean void fraction fields, which suggests that the compressibility effects on cavitating vortex shedding can be neglected. For the cavitating vortex street flow behind a blunt trailing edge hydrofoil NACA 0009, high-fidelity numerical simulations have been established in the current thesis. Based on the results, it has been observed that cavitation has a significant impact on the wake flow dynamics, notably increasing the shedding frequency of the primary vortices. Additionally, cavitation growth leads to increased hydrodynamic loads on the hydrofoil surface. Furthermore, cavitation development enhances the advected velocity of the vortices while decreasing the streamwise inter-vortex spacing. Both factors are believed to contribute to the increase of the vortex shedding frequency while the reduction of streamwise inter-vortex spacing tends to dominate this increase.The numerical results related to cavitating vortex street flow behind a blunt trailing edge hydrofoil NACA 0009 subjected to forced oscillation have shown that the induced dynamic response due to the oscillation is influenced by the presence of cavitation. In the lock-in regime, cavitation appears to widen the upper bound of this regime and cause a decrease in the added moment of inertia and an increase in the added damping. Moreover, the timing of the vortex shedding changes with the presence of cavitation. On the other hand, the oscillation of the hydrofoil affects the dynamics of cavitation in terms of cavitation inception and cavity length. Generally, the cavitation inception number gradually increases with the forced oscillation frequency. Meanwhile, approaching the bounds of the lock-in regime will cause local decreases in cavitation inception numbers. Besides, the length of the cavitating wake is influenced by the variation of the oscillation frequency, and the maximum cavitating wake length occurs under stationary conditions.
  

DOCTORAL DEGREE IN NETWORK ENGINEERING

• CEPEDA PACHECO, JUAN CARLOS: Contribution to the enhancement of IoT-based application development and optimization of underwater communications, by artificial intelligence, edge computing, and 5G networks and beyond, in smart cities/seas
  
  Author: CEPEDA PACHECO, JUAN CARLOS
  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 NETWORK ENGINEERING
  Department: Department of Network Engineering (ENTEL)
  Mode: Normal
  Deposit date: 22/04/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: DOMINGO ALADREN, MARIA DEL CARMEN
  Committee:
       PRESIDENT: LLORET MAURI, JAIME
       SECRETARI: REMONDO BUENO, DAVID
       VOCAL: HUERTA, MÓNICA KAREL
  Thesis abstract: 6G networks have emerged as a revolutionary breakthrough, promising ultra-fast and reliable connectivity that redefines the way we interact with the digital world. This new generation of networks not only drives communication between devices but is also the backbone of the Internet of Things. In addition, the learning and adaptive capabilities of Artificial Intelligence systems are driving process automation and efficiency. Similarly, Edge Computing complements this landscape by decentralizing data processing, bringing computing capacity closer to the sources of information. This allows for reducing latency and improving efficiency byprocessing data in real-time, driving critical applications that require instantaneous responses.This thesis focuses on two important points: 1) Improving the efficiency of applications in smart cities, and 2) Enhancing the efficiency of underwater communications in smart coastal cities by applying artificial intelligence, edge computing, and 5G and beyond. To achieve these objectives, an exhaustive study of the existing literature on 5G and beyond networks, smart cities, and artificial intelligence has been carried out. In addition, technical documentation to obtain an updated view of the different technologies that enable the development of applications based on 5G and beyond has been analyzed. Aiming to generate newand innovative alternatives in the field of tourism, security, improved underwater communications, and marine discovery that drive promote development to meet the needs of citizens in smart cities and ocean/sea. As a result of this study, the first contribution has emerged. It involves the analysis, design, and implementation of a tourist attraction recommendation system employing a deep learning algorithm tailored for smart cities. The primary objective is to improve how tourist attraction recommendations are made so that they are tailored to the requirements of each visitor in a given city and thereby reduce the time it may take a visitor to search for possible places to visit.The second contribution arises in surveillance and security, which consists of a distraction detection system for the prevention of drowning in aquatic places, developed in a 5G and beyond network environment. For this goal, an approach of surveillance cameras capturing images of people in charge of minors in swimming pools or beaches was proposed; and employing an ML algorithm (convolutional neural networks) to classify the type of distraction that a person in charge of a minor may have.Finally, the third contribution is presented, called reinforcement learning and mobile edge computing for 6G-based underwater wireless networks. In this approach, a submerged edge mobile computing architecture is presented in which an AUV is used as a mobile platform (MEC), in addition, several local AUVs equipped with computational resources that collect tasks from sensor nodes and can make the decision to process them locally or partially or fully offload them to the mobile edge computing AUV device. To this end, an algorithm based on deep reinforcement learning (DDPG) is proposed for trajectory control, task offloadingstrategy, and computational resource allocation, combined with mobile edge computing and AUVs to improve underwater communication; aiming to minimize the sum of maximum processing delays and energy consumption during the whole process of executing a task.The contributions presented in this doctoral thesis are of singular importance, since to date they continue to be innovative. The contributions presented not only represent significant advances in their respective areas but also lay the groundwork for future research and developments in smart city construction and underwater communications optimization, thereby reinforcing the transformative potential of artificial intelligence, edge computing, and advanced wireless networks in these domains.
  
• HAASTRUP, ADEBANJO: Enhanced Dynamic Bandwidth Algorithms for Passive Optical Networks
  
  Author: HAASTRUP, ADEBANJO
  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 NETWORK ENGINEERING
  Department: Department of Network Engineering (ENTEL)
  Mode: Normal
  Deposit date: 22/04/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: RINCON RIVERA, DAVID | PINEY DA SILVA, JOSE RAMON
  Committee:
       PRESIDENT: KHALILI, HAMZEH
       SECRETARI: SPADARO, SALVATORE
       VOCAL: PAPAGIANNI, CHRYSA
  Thesis abstract: The telecommunications industry faces rapid changes due to the deployment of ultra-high speed access networks (5G and beyond, fiber-to-the-home), promising unparalleled experiences with high bandwidth and low latency. However, this transition brings challenges. With the surge in smart device numbers and bandwidth demand, optimizing network architecture, management, and resource usage is crucial for cost-efficiency. Passive Optical Networks (PONs) offer efficient broadband access for residential and commercial sectors, with advantages like energy efficiency and robust security and high performance. Leading organizations, such as IEEE and ITU-T, are actively developing standards to increase the capabilities of next-generation PONs. The goal is to meet the demands by implementing innovative mechanisms for efficient management, resource allocation, QoS, energy savings, and low latency.Next-generation PONs have introduced the use of multiple wavelengths based on TWDM techniques. However, managing multiple wavelengths presents challenges, as DBA algorithms need to consider both the time and wavelength dimensions of the network. This follows a Joint Time and Wavelength Scheduling (JTWS) scheme, which requires complex implementation. TWDM-PON also utilizes tunable transceivers in ONUs to switch between wavelengths, but this introduces a delay called Laser Tuning Time (LTT) which is often ignored, but it is an important consideration when designing our DBA algorithms. Additionally, there is a demand to integrate metro and access networks for streamlined telecom infrastructure. Long Reach PON (LRPON) offers a solution by expanding coverage from 20 km to 100 km, enabling high-speed, long-distance data transmission over optical fibers. This reduces the need for central offices, resulting in cost savings. However, the extended reach of LRPONs introduces new challenges, particularly in the area of DBA algorithms. Traditional DBA algorithms like IPACT may not be as efficient for LRPONs due to increased propagation delays and round-trip times (RTT) between the OLT and ONUs. To address these challenges, a novel DBA algorithm called the Distance Weighted DBA (DWDBA) algorithm is proposed.This thesis delves into the limitations of traditional DBA algorithms and proposes novel Enhanced DBA solutions for PONs. Leveraging techniques such as the Longest Processing Time (LPT) scheduling method to minimize queue delays, our DBAs also consider the concept of laser tuning time to bring a practical, real-world approach to our system. The main contributions of this thesis are: - Incorporating the often-overlooked laser tuning time (LTT) concept in our analysis of DBA for TWDM PONs, therefore obtaining more realistic results. - Introducing an innovative algorithm for PONs employing LPT to minimize queue delay and enhance throughput, resulting in a notable reduction (up to 73%) with respect to the queue delay when compared to IPACT. - Developing a Distance Weighted DBA (DWDBA), specifically tailored for LRPONs, aimed at preventing the penalization of ONUs located farther from the OLT. This results in improving up to 30% and 10% the queue delay and throughput, respectively, over IPACT.The effectiveness of these proposed algorithms is rigorously evaluated through comprehensive simulations, demonstrating their potential to meet the demands of future networks.
  

DOCTORAL DEGREE IN OPTICAL ENGINEERING

• BALLESTA GARCIA, MARIA: Propagation of polarized light through turbid media: Application of lidar technology in foggy environments
  
  Author: BALLESTA GARCIA, MARIA
  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 OPTICAL ENGINEERING
  Department: Department of Optics and Optometry (OO)
  Mode: Normal
  Deposit date: 22/04/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: ROYO ROYO, SANTIAGO
  Committee:
       PRESIDENT: ARTEAGA BARRIEL, ORIOL
       SECRETARI: VILASECA RICART, MERITXELL
       VOCAL: BIJELIC, MARIO
  Thesis abstract: In recent times, there has been a growing interest in LiDAR imaging systems for outdoor applications involving computer vision, such as automotive systems, surveillance, and robotics. LiDAR sensors have the ability to capture 3D data, that is, the geometry (volume, distances) of the scenes involved, complementing the 2D projections of scenes available in conventional cameras. However, their limited tolerance to adverse weather conditions, particularly fog, stays as one of the obstacles that hinders their complete settlement. This Thesis aims to evaluate the potential of utilizing the polarization properties of light and the digitization of the signal to improve the system¿s imaging capabilities in such challenging conditions. Additionally, our research offers valuable insights in the domain of imaging through fog. Understanding the interaction of polarized light with turbid media and recognizing the importance of the targets¿ polarimetric properties within the imaged scene is essential for optimizing the performance of polarimetric imaging systems.To achieve our goal, a preliminary investigation to examine the characteristics of polarimetric imaging through fog is undertaken. Our findings indicate that polarimetric imaging modes provide higher contrast compared to intensity-based imaging modes, facilitating the identification and segmentation of different targets. Additionally, experimental characterization of the depolarizing behavior of light through fog is conducted for both reflection and transmission imaging modes. The results suggest that, in this scenario, light behavior falls within the scattering regime of the polarization memory effect, with a significantly reduced depolarization in circularly polarized beams when compared to linearly polarized ones. To the best of our knowledge, this Thesis quantifies for the first time the differences between the performance of both polarization modes in fog conditions. Next, a Monte Carlo-based model is developed to meet the requirements of our LiDAR prototype. Considering the resource-intensive nature of experiments conducted in fog conditions and the dynamic nature of fog, the model¿s ability to accurately simulate the physics of the problem, including a realistic fog environment, helps to guide the definition of the future experimental actions. Subsequently, the model is utilized to simulate and analyze various aspects relevant to the design of the system, including polarization configurations, interactions with targets, and irregularities in the media (in practice, generalizing the scattering media beyond fog to e.g. sand or smog), together with the characteristics of the acquired signal. Finally, this Thesis presents a novel polarized LiDAR imager prototype and evaluates its performance in fog conditions. It conclusively shows that using circularly polarized light and a cross-configuration detection setup significantly improves system performance in such scenarios. This system effectively tackles challenges induced by scattered light, reducing saturation effects from backscattering, mitigating scattering noise in point clouds, and enhancing target detection, especially for highly reflective surfaces like metallic targets. This approach offers an innovative, straightforward, and efficient method for signal stabilization and enhancement of the point cloud quality by relying on the inherent physics of the problem.
  

DOCTORAL DEGREE IN PHOTONICS

• KNAPP, CHRISTIAN: Quantitative Fluorescence Imaging of Spatiotemporal Dynamics of DNA Damage and DNA Replication in Health and Disease
  
  Author: KNAPP, CHRISTIAN
  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 PHOTONICS
  Department: Institute of Photonic Sciences (ICFO)
  Mode: Normal
  Deposit date: 30/04/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: GARCÍA PARAJO, MARÍA | CAMPELO AUBARELL, FELIX
  Committee:
       PRESIDENT: MANZO, CARLO
       SECRETARI: KRIEG, MICHAEL
       VOCAL: SIMÖES DA SILVA CARDOSO, MARIA CRISTINA
  Thesis abstract: Genomic instability, caused by DNA damage, is the main determinant for cancer and aging. To safeguard genomic integrity, cells evolved complex mechanisms to ensure error-free DNA replication and DNA damage repair. However, cells are not always able to repair DNA damage, and have to halt proliferation in a state of senescence, or perform the programmed cell death, apoptosis, to prevent giving rise to tumors and to protect the organism. Yet, this loss of proliferative potential ultimately leads to aging of the organism.The significance of DNA damage repair is underlined by mutations in genes encoding DNA repair proteins, which lead to premature aging diseases associated with a wide spectrum of early-onset age-related diseases. Notably, Hutchinson-Gildford progeria syndrome (HGPS), the most severe premature aging disease, is not caused by mutations in a DNA repair protein, but in the nuclear intermediate filament protein lamin A. Nonetheless, DNA damage is considered a main driver of this disease.The affected protein lamin A is a main component of the nuclear lamina, which is an intermediate filament meshwork and one of the layers of the nuclear envelope which surrounds the nucleus. To date, the pathological mechanism how the mutant form of lamin A leads to DNA damage in HGPS is poorly understood.Here, we propose our hypothesis that this mutations disturbs the interactions between the nuclear lamina and peripheral DNA in a manner that mechanically interferes with the local progression of DNA replication sites. Consequently, our hypothesis predicts that DNA damage predominantly arises during DNA replication of peripheral DNA in close proximity to the nuclear lamina. This creates a spatial correlation between the occurrence of DNA damage and the nuclear periphery, as well as a temporal correlation with DNA replication of peripheral DNA which occurs during late S-phase of the cell cycle.Hence, in Chapter 3, we present our approach to characterize the spatiotemporal dynamics of DNA damage throughout the cell cycle. This approach employs simple reporter cell models of DNA damage and DNA replication, along with long-term multi-color fluorescence live cell imaging microcopy, and a quantitative analysis pipeline. This analysis pipeline monitors and follows cells over multiple days and quantifies DNA damage foci formed by fluorescent DNA damage repair proteins, and employs machine learning-based algorithms to classify distribution patterns of the DNA replication protein PCNA to perform post hoc in silico synchronization of cell cycles. In Chapter 4, we describe how we employed this approach to quantify DNA damage foci and to characterize their distributions throughout the cell cycle in cell models of HGPS. We conducted these experiments under different conditions and with different cell lines, however we could not detect differences between HGPS cell models and healthy controls. Finally, we discuss our findings as well as technical and biological aspects of our approach in the context of literature.In Chapter 5, we present an approach which we developed to study the influence of the mutant form of lamin A on the mobility of DNA replication sites, and thus to test the mechanical aspects of our hypothesis. This approach is based on single molecule tracking of the DNA replication protein PCNA. While we could not detect differences between HGPS cell models and healthy controls with this approach, we revealed two slow mobility states of PCNA within DNA replication sites. These two mobility states are consistent the the PCNA meshwork model proposed by Boehm et al. in 2016 and may represent DNA replication condensates.Finally, in Chapter 6, we summarize the main results of this thesis and discuss future and potential applications of our approaches to advance our understanding of the cell cycle-dependent dynamics of genome maintenance, and the structural organization of DNA replication sites.
  
• LIN, LI CHUN: Deciphering the role of mechanical stress during ageing and in neurodegenerative diseases
  
  Author: LIN, LI CHUN
  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 PHOTONICS
  Department: Institute of Photonic Sciences (ICFO)
  Mode: Normal
  Deposit date: 29/04/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: KRIEG, MICHAEL
  Committee:
       PRESIDENT: MARTÍN BLANCO, ENRIQUE
       SECRETARI: SANDOVAL ÁLVAREZ, ÁNGEL
       VOCAL: PEREZ BROWNE, MARCOS FRANCISCO
  Thesis abstract: The locomotion of Caenorhabditis elegans (C. elegans) offers a unique platform for studying complex postures and motor behaviors. In this study, I investigated locomotor patterns across different ages and genetic backgrounds of C. elegans, utilizing customized tracking systems and advanced analysis techniques. A comprehensive examination of locomotion behaviors was conducted using the eigenworm approach. Eigenworms are the principal components of the animals¿ posture space. I identified specific eigenworms associated with forward movement, turning, and exaggerated bends. Notably, spectrin-mutant animals showed a strong correlation between their bending movements and a specific eigenworm for turning in wild-type animals. These findings suggest that eigenworms offer a universal framework to compare different types of worm movement and assess the effects of mutations. This paves the way for a more informative analysis of worm behavior, especially when combined with studies of neuronal networks.Additionally, I explored the role of proprioception in coordinating motor activities within C. elegans, employing genetic and modeling approaches. The focus of my research was to elucidate the mechanisms underlying proprioceptive feedback, including mechanical stress and neuronal signaling, with a focus on age-related deficits. My findings elucidate that the spectral network associated with a singular proprioceptive DVA interneuron, which modulates tension and compression states, serves as a critical determinant of body posture. Intriguingly, a striking resemblance was observed between animals of early ageing and the mutant animals for ß-spectrin, where both animals crawled with exaggerated body bends. Moreover, I show that proprioceptive neurons are found to encode body posture and exhibit age-dependent structural and functional alterations, including protein aggregation and decreased mechanical tension. Notably, spectrin, a cytoskeletal component, emerges as a key player in maintaining proprioceptive integrity during ageing.Furthermore, I investigated the molecular pathways underlying age-associated proprioceptive defects, more specifically, the role CLP-1 protease in the cleavage of UNC-70/ß-spectrin in ageing animals. Conditional knockout of clp-1 in DVA interneuron revealed altered locomotor behaviors, along with the pan-neuronal knockout of clp-1. Given the role of spectrin in proprioception through DVA interneuron suggests that clp-1 regulates spectrin in age-related neurodegeneration. Lastly, I explored the effect of ectopic expression of human ¿ßcrystalline on ageing. We hypothesized that ¿ß-crystallin (HSPB5), a small heat shock protein (sHsp), will stabilize ß-spectrin and shield it from clp-1 proteolytic degradation during ageing. I ectopically expressed the constitutively active 3E mutant of ¿ß-crystallin pan-neuronally or specifically in DVA. Through locomotion analysis of animals from young adult to adult day 6, I observed a modest rescue in the locomotion behavioral pattern in both DVA specific and pan-neuronally expressed ¿ß-crystallin animals. We speculate that constitutively active ¿ß-crystallin may bind to proteolytically vulnerable domains/residues of the UNC-70 protein, providing protection against proteases such as clp-1. Collectively, these findings contribute to our understanding of proprioceptive mechanisms in ageing and offer insights into potential therapeutic targets for age-related neurodegenerative diseases.
  

DOCTORAL DEGREE IN POLYMERS AND BIOPOLYMERS

• FERRERES CABANES, GUILLEM: Hybrid metal-organic nanoparticles for antimicrobial applications
  
  Author: FERRERES CABANES, GUILLEM
  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 POLYMERS AND BIOPOLYMERS
  Department: Department of Chemical Engineering (EQ)
  Mode: Normal
  Deposit date: 03/04/2024
  Reading date: 21/06/2024
  Reading time: 11:00
  Reading place: Sala de Conferències de l' ESEIAAT (Escola Superior d¿Enginyeries Industrial, Aeroespacial i Audiovisual de Terrassa), C/ Colom, 1-11, 08222 Terrassa.
  Thesis director: TZANOV, TZANKO | TORRENT BURGUES, JUAN
  Committee:
       PRESIDENT: PASHKULEVA, IVA HRISTOVA
       SECRETARI: GARRIGA SOLE, PERE
       VOCAL: VASSILEVA, ELENA
  Thesis abstract: Antimicrobial resistance (AMR) is a global health concern, which leads to increased morbidity and mortality, huge economic burden to the healthcare systems and potentially untreatable infections. Due to the inappropriate use of antibiotics, the natural adaptation has been accelerated and bacteria have developed multiple ways to degrade, alter, or expel drug molecules. Besides these resistance mechanisms, bacteria can adhere to surfaces and grow as biofilms ¿ organised assemblies of surface-bound cells, enclosed in a self-produced extracellular polymer matrix (EPM). The EPM holds the pathogens together, enables adhesion to surfaces, and enhances the tolerance to host immune responses and antibiotics compared to free-floating cells. Metal nanoparticles (NPs) have been suggested as a potential solution to fight resistant bacteria due to their strong antimicrobial activity and versatile mechanisms of action. However, inherent toxicity towards mammalian cells and large variation of physical properties are challenges that preclude the clinical application of such materials. In this thesis, metal NPs have been combined with different biomolecules for enhanced biocompatibility, increased antimicrobial efficacy, and enabling new functionalities to mitigate AMR.The first part of the thesis describes the formation of Ag NPs using bioactive macromolecules to produce multifunctional nanostructures. First, the matrix-degrading enzyme (MDE) ¿-amylase was used to reduce Ag(I), yielding NPs with antimicrobial and biofilm-degrading activity towards both gram-positive and gram-negative bacteria. Then, chitosan-Ag NPs were decorated with the quorum-quenching enzyme (QQE) acylase I, which combination was able to kill Pseudomonas aeruginosa, hinder biofilm formation, and inhibit bacterial quorum sensing (QS) based on acyl homoserine lactones (AHLs). Finally, adipic acid dihydrazide (ADH) was grafted on hyaluronic acid (HA) and used to form Ag NPs. The modified polymer (HA-ADH) played a crucial role in the interaction of the NPs with bacterial membranes, assessed using Langmuir isotherms, and reduced the toxicity of Ag towards human cells. In the second part of the thesis, HA-ADH and epigallocatechin gallate (EGCG) were used to produce nanostructured complexes with a scarcely studied antimicrobial Co(II). On one hand, Co(II) formed a complex with the biopolymer, which complex was transformed to antimicrobial nanogels (NGs) using an ultrasonic approach. On the other hand, incubation of EGCG with Co(II) yielded nanostructured metal-phenolic networks (MPN). These cobalt-containing NPs were active towards both gram-positive and gram-negative bacteria, and were able to inhibit biofilm formation due to the capacity of ECGC to disrupt QS. The last chapter of the thesis validates the use of the novel nanomaterials for antimicrobial functionalisation of medical devices. Coating of contact lenses with NGs hindered bacterial colonisation and unspecific absorption of proteins without affecting the optical properties and comfort of the material. Inclusion of MPN NPs in thiolated hyaluronic acid (THA) hydrogels endowed these materials with properties promoting efficient chronic wound treatment. The antibiotic-free hydrogels were able to control the main factors of wound chronicity by inhibiting the activity of deleterious wound enzymes, scavenging reactive oxidative species, and demonstrating pronounced antimicrobial activity, resulting in similar to commercial products wound management efficacy confirmed in vivo.
  
• MARTÍ BALLESTÉ, DÍDAC: Advanced molecular modelling techniques for immunosensor nanointerfaces
  
  Author: MARTÍ BALLESTÉ, DÍDAC
  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 POLYMERS AND BIOPOLYMERS
  Department: Department of Chemical Engineering (EQ)
  Mode: Normal
  Deposit date: 13/03/2024
  Reading date: 03/06/2024
  Reading time: 11:30
  Reading place: Sala Polivalent de l'Edifici I, Edifici I, planta baixa, Campus Diagonal-Besòs
  Thesis director: TORRAS COSTA, JUAN | ALEMAN LLANSO, CARLOS ENRIQUE
  Committee:
       PRESIDENT: POATER TEIXIDOR, ALBERT
       SECRETARI: SASSELLI RAMOS, IVAN
       VOCAL: CREHUET SIMON, RAMON
  Thesis abstract: Viruses and their infections have always affected human lives throughout history. Globalization contributed positively to the progress of human society in science and medicine which permited to deal with viruses, but the reality is that the number of infections does not decrease over the years. Globalization itself is here agin one of the main factors, as people move in more densely populated areas, which favors the spread of viruses. Another important factor is the viruses themselves, which over the years have shown a constant evolution that allowed them to adapt to new hosts. For these reasons, human-led efforts such as vaccines, antiviral treatments, sensors etc. are critical tools for human survival, and like viruses, humans must continue to innovate. This thesis focused on providing different understandings of a series of biochemical processes at molecular the level to facilitate the design of plasmonic resonance sensors, currently used for detecting diseases such as cancer, to enable a similar detection improvement in other viruses and diseases such as HIV and SARS-Cov-2.This thesis is divided into two parts, with the first focusing on the characterization related to the HIV virus. Several studies have been carried out using a combination of different molecular simulation techniques, classical dynamics, quantum mechanics and hybrid QM/MM-MD methods. These studies characterize the behavior of the antibody chosen in the design of the sensor, IgG1 , as well as its interactions with the silica surface that compounds the sensor and its orientation once functionalized on top of the surface. Additional studies were performedm focusing on the interaction between the immunoglobulin G and the glycoprotein that forms part of the HIV virus spike, and permited to identify the interactions helping the antibody to attach to the virus for the virus inhibition.In the second part, the same molecular simulation techniques have been used to study the virus which completely changed the world in 2020, SARS-CoV-2 known for the disease COVID19. As this virus was new at the time of the thesis, there was a dramatic lack of knowledge. Molecular modelling techniques were used to study the behavior of the virus spike in presence of heat or solvated in water. Similar studies to the case of HIV-IgG1 were performed between SARS-CoV-2 spike and different promising antibodies with the goal to identify the best candidate for sensor functionalization or virus inhibition. In this section, the interaction between the virus spike and the ACE2 enzyme, the target cell that SARS-CoV-2 use to infect human body, was also characterized. Finally, new antibodies were designed combining the previous ones with IgG1 and their behavior was studied in the presence of the sensor¿s silica surface and the nanoparticles gold surface used in the detector
  

DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS

• UDAONDO GUERRERO, CARLOS: Analysis of Q factor degradation mechanisms in BAW resonators
  
  Author: UDAONDO GUERRERO, CARLOS
  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: 22/03/2024
  Reading date: 17/06/2024
  Reading time: 11:00
  Reading place: Edifici C4-028-2, EETAC, Esteve Terradas, 7, Campus UPC, 08860.-Castelldefels (Barcelona)
  Thesis director: COLLADO GOMEZ, JUAN CARLOS | MATEU MATEU, JORDI
  Committee:
       PRESIDENT NO PRESENCIAL: AIGNER, ROBERT
       SECRETARI: VALENZUELA GONZALEZ, JOSE LUIS
       VOCAL NO PRESENCIAL: VILLANUEVA TORRIJO, LUIS GUILLERMO
  Thesis abstract: The emergence of smartphones not only changed the way people uses its phone for, but it also changed the traffic amount that networks need to carry, increasing the demand of higher data rates. The overall result was the appearance of 4G networks, and nowadays, the current development of 5G, implying the need for more frequency bands, and the application of new techniques such as Carrier Aggregation (CA), MIMO antennas, and so on. All these market driven necessities suppose a great challenge for the radiofrequency (RF) industry, which have been facing the necessity of miniaturization and band coexistence on its devices since the beginning of mobile communications.Microwave filters based on Bulk Acoustic Wave (BAW) resonators, have been able to this day to overcome these limitations. These devices consist in a thin piezoelectric layer comprised by two metal electrodes, and an acoustic confinement method, which can be simply made of air or a Bragg reflector. The use of electroacoustic technology enables to reduce the filter size up to five orders of magnitude, allowing the integration of multiple filters in handsets. This thesis focuses on modelling some of different physical phenomena at the resonator level that affect the performance of the filters.The first part of this thesis is the one regarding the spurious response of BAW resonators. This response is originated by acoustic waves traveling in the lateral dimension of the resonator. These waves couple electromechanically, degrading the filter response. BAW filters have been capable of overcoming this limitation suppressing them by the use of different electrode geometries (Apodization), or by surrounding the electrode by a decreased, or increased frame (Border Ring). The nature of these waves is studied through the thesis and several equivalent models are proposed in order to accurately predict them, helping to the design of the correspondent suppression structures. One of this thesis contributions regarding the lateral spurious resonances, consists in making use of a modified Mason model to determine the origin of the additional spurious resonances generated by the Border Ring. These resonances can be attributed to an acoustic mode, different from the fundamental, propagating across the resonator stack. By adding nonlinear sources to that model, the second harmonic (H2) emissions and the impact of the spurious resonances in them, is also studied.Finally, a new equivalent model based in the Transmission Line Matrix (TLM) method is proposed for the acoustic cavity of a BAW resonator. This new approach is able to model resonators with different electrode geometries, in a much faster way than traditionally used methods like the Finite Elements Method (FEM). In addition, by determining different propagation regions, it can be used to model both the apodization and the Border Ring at the same time.The second family of contributions are the ones regarding to the thermoelastic behavior of the BAW resonators. A solid heats up when compressed and vice versa. In a harmonic oscillation, when heat is able to flow through the solid regions, this flow from hotter to colder regions generates a relaxation of the acoustic wave. This is the thermoelastic damping. A thermo-electro-mechanical Mason model is used for quantifying this source of losses on BAW resonators. The model is compared with experimental data taken at cryogenic temperatures and an analysis of losses of the broadband spurious resonances of the Bragg reflector has been performed.
  

DOCTORAL DEGREE IN STRUCTURAL ANALYSIS

• AGUIRRE RUZ, ALEJANDRO: Numerical approximation of thin structures using stabilized mixed formulations for Infinitesimal and Finite Strain theories, including Fluid-Structure Interaction problem applications.
  
  Author: AGUIRRE RUZ, ALEJANDRO
  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 STRUCTURAL ANALYSIS
  Department: (DECA)
  Mode: Normal
  Deposit date: 22/04/2024
  Reading date: 24/05/2024
  Reading time: 12:00
  Reading place: Aula C1002, Edifici C1, Campus Nord ETSECCPB (Escola Tècnica Superior d'Engineria de Camins, Canals i Ports de Barcelona)
  Thesis director: CODINA ROVIRA, RAMON | BAIGES AZNAR, JOAN
  Committee:
       PRESIDENT: ROMERO OLLEROS, IGNACIO
       SECRETARI: ROSSI BERNECOLI, RICCARDO
       VOCAL NO PRESENCIAL: COLOMÉS GENÉ, JOSEP ORIOL
  Thesis abstract: The theories of thin structures can be classified into two main branches depending upon whether shear deformation in the transverse direction is taken into consideration or not. In this context, theories accounting for shear deformations prove suitable for modeling structures with both thin and thick profiles. In the Finite Element context, they are referred to as C0 theories due to the minimum continuity order of shape functions required to pose a discretized approximation. However, there are space incompatibilities in the standard discrete approximation that exhibits spurious solutions, particularly evident in thin structures. These instabilities, known as numerical locking, result in an artificial stiffening of the structure, whose effect becomes more pronounced for thinner structures. Various forms of numerical locking can be triggered, influenced not only by the slenderness of the structure but also by its shape and the nature of the applied loads. In this context, flat structures are prone to shear locking when exposed to transverse loads. Conversely, curved structures may confront different mechanisms leading to various forms of numerical locking, namely membrane, thickness, and trapezoidal locking. The initial part of the study aims to develop a specialized framework to address instabilities in the context of flat structures in the context of Reissner-Mindlin theory. Subsequently, the second part of the study aims to expand the framework to effectively address instabilities arising in of curved structures in the context of Solid-Shell elements. The locking problem is approached by means of a mixed formulation that considers displacements and stress as unknowns in a curvilinear coordinate framework. This approach allows to isolate the components of the stress tensor in order to study the mechanisms in which every type of numerical locking are triggered. The third part of the thesis is dedicated to integrating the previous advancements into Finite Strain analysis by the inclusion of standard hyperelastic constitutive behavior. With this approach, the problem becomes even more difficult to solve because of the non-linearity and the large deformations the shell is subject to. Lastly, the fourth and final part is dedicated to addressing the Fluid-Structure Interaction problem using an embedded mesh approach, which has consistently been a topic of great research interest in the literature, because of its complexity and wide variety of applications. This problem introduces a variety of challenges that have to be properly addressed: the discontinuous pressure field arising for the structure separating the fluid domain, the computation and imposition of transmission conditions between domains, the coupling strategy, and the algorithmic work needed to join all of these ingredients together. This thesis mainly focuses on overcoming challenges associated with thin structures when employing the conventional Galerkin Finite Element approach. It seeks solutions through stabilized methods, specifically within the Variational Multiscale framework. As result, the formulations developed through the investigations have proven to be robust, allowing to model locking-free thin structures efficiently, and to accurately describe the physics of thin shells immersed in fluid flows and being subject to large deformations.
  

DOCTORAL DEGREE IN SUSTAINABILITY

• CAICEDO MAFLA, MARÍA ANGÉLICA: Design of bike networks adaptive to heterogeneous demands and the needs of social groups. Case study: Bike mobility networks for the cities of Quito and Guayaquil, Ecuador.
  
  Author: CAICEDO MAFLA, MARÍA ANGÉLICA
  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 SUSTAINABILITY
  Department: University Research Institute for Sustainability Science and Technology (IS.UPC)
  Mode: Normal
  Deposit date: 11/04/2024
  Reading date: 13/06/2024
  Reading time: 11:00
  Reading place: ETSECCPB, C/Jordi Girona 1-3, edifici C1, sala 002, Campus Nord, Barcelona.
  Thesis director: ESTRADA ROMEU, MIGUEL ANGEL | MAYORGA CÁRDENAS, MIGUEL YURY
  Committee:
       PRESIDENT: MOURA BERODIA, JOSE LUIS
       SECRETARI: MARTÍNEZ DÍAZ, MARGARITA
       VOCAL: DE OÑA, ROCÍO
  Thesis abstract: Bike¿s recognition as a vital form of urban transportation underscores its capacity to enhance mobility, improve quality of life, and address several urban challenges such as air pollution, traffic congestion, and greenhouse gas emissions. This thesis explores bike¿s potential, emphasizing the importance of developing infrastructure, involving the community in mobility planning, and promoting policies to maximize its benefits.The study employs a dual-pronged approach to investigate the complexities of integrating cycling into urban transportation systems. It applies a sociological perspective to identify and assess barriers to bike use and their relationship with urban characteristics. Using ordered probit models, factors such as road insecurity, linked to the lack of adequate bike infrastructure, and topography, are highlighted. Concurrently, an engineering perspective guides the design of cycling networks to cater to varied demand, user types (differentiated by bike ownership and vehicle type), and topographies, reflecting real-world conditions. The optimal bike network results from minimizing the general system costs, including both agency and user costs. For flat terrains, continuous approximation techniques optimize network efficiency and accessibility, considering the heterogeneous demand and various user types, based on bike ownership and travel chains. In contrast, for cities with varied topographies, discrete approaches incorporate topographical elements into the model. Network performance and structure are evaluated based on two route selection criteria based on vehicle type: minimizing energy for traditional bike users and minimizing time for e-bike users. This engineering perspective aims to develop cycling networks that are practical and responsive to the diverse needs of urban dwellers.The methods are empirically validated through case studies in Quito and Guayaquil, Ecuador, showcasing their efficacy in developing adaptive bike networks tailored to diverse urban contexts, thereby significantly enhancing bike mobility across varied settings.The study's findings indicate that the network's layout, including lane spacing and station locations, is primarily influenced by the concentration of trip origins and destinations rather than topography. However, topography does affect route selection, which in turn influences flow distribution and infrastructure utilization. Moreover, the variation in trip distribution across different user types has a minimal impact on the network's lane configuration but significantly affects the number of bike-sharing stations and fleet size. The necessity for a safety stock at each station leads to an oversized fleet, increasing agency costs. Despite being an individual mode of transport, the study highlights that bike-sharing systems benefit from economies of scale. As demand increases and becomes more concentrated, the cost per user decreases, resulting in denser lane networks and improved network efficiency. E-bikes emerge as a viable solution for overcoming topographical barriers, offering a significant advantage in areas with steep slopes. For instance, where users of traditional bikes might need to walk, thereby increasing overall journey times, e-bike users experience reduced travel times and physical exertion, making e-bikes efficient in urban contexts with varied topographies.Future research directions and policy recommendations are proposed, highlighting the importance of a holistic and adaptive approach to bike mobility planning. This includes integrating diverse weather-related variables, exploring other personal mobility vehicles (PMVs), and employing robust datasets to inform sustainable urban transport strategies.
  
• ORNELAS HERRERA, SELENE IVETTE: PREFERENCIAS DE LOS CONSUMIDORES Y AGRICULTORES HACIA UN SISTEMA AGROALIMENTARIO MÁS SOSTENIBLE
  
  Author: ORNELAS HERRERA, SELENE IVETTE
  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 SUSTAINABILITY
  Department: University Research Institute for Sustainability Science and Technology (IS.UPC)
  Mode: Normal
  Deposit date: 17/04/2024
  Reading date: 24/05/2024
  Reading time: 11:00
  Reading place: Sala Polivalente de la Escola d'Enginyeria Agroalimentària i de Biosistemes de Barcelona (Castelldefels)
  Thesis director: KALLAS CALOT, ZEIN
  Committee:
       PRESIDENT: SÁNCHEZ GARCÍA, M. MERCEDES
       SECRETARI: RAHMANI MEDDOUR, DJAMEL
       VOCAL: IGLESIAS MARTÍNEZ, EVA
  Thesis abstract: The adaptation of the agri-food system towards more sustainable models is a pressing need to guarantee food security for current and future generations, in the face of population growth, scarce natural resources and climate change. To meet the challenges of producing more sustainably, new food production systems have been developed, they incorporate the principles of circular economy. Circular production systems reduce the consumption of new external inputs and the generation of waste, reducing adverse environmental effects and allowing the recovery of nutrients. This thesis addresses two of the main links in the shortest value chain of the agri-food system, "the producer and the consumer", and their response towards the incorporation of sustainability approaches, such as circularity. The objective is to analyze whether the circular agriculture practices identified as more sustainable are accepted by agricultural producers and the factors that influence their adoption, as well as the preference of consumers and their willingness to pay for these circular production innovations, in order to try to convert the results obtained into evidence that can serve as a basis for generating adequate and coherent public policies, to support and facilitate the adoption of circular innovations. . In relation to the above, in the first instance a semi-structured questionnaire was applied to agricultural producers from: Spain, Austria, Czech Republic and Italy, in which the hierarchical analysis method (AHP) to measure preferences and the scale of the New Ecological Paradigm NEP were included to measure environmental attitudes. Results showed an adoption readiness of 48.24% and that the acceptance of the proposed circular innovations is closely related to the environmental objectives, level of education, previous adoption experience and environmental attitudes of farmers. We also found that institutional support plays an important role in adoption decisions. With regard to consumers, in a first approach, through a survey of 5,246 consumers in Germany, the Netherlands, Italy, the Czech Republic and Spain, their willingness to pay for beef fillet produced in a circular livestock system was analyzed, using the Discrete Choice Experiments (DCE) method. This study included the analysis of the behaviors that influence their preferences, based on the Theory of Planned Behavior (TPB). The results allowed us to observe that there is a potential market for circular beef fillet. Although preferences are heterogeneous, consumers are generally willing to pay a higher premium for circular beef steak than conventional steak and lower than for organic beef. Of the components of planned behavior theory, social norms and behavioral control perception increased preferences for circular production beef steak, while environmental attitudes increased preferences for organic beef steak, and reduced preference for conventional beef steak. Subsequently, the preferences of 5,591 consumers in Spain, Poland, Italy, Hungary, Croatia and Belgium were analyzed, as well as their willingness to pay for pork, milk and bread labelled as circular and presented as more sustainable, in terms of reducing greenhouse gas emissions and optimizing nutrients. This analysis included sustainable consumption behavior, focused on purchasing, use, and recycling habits. The results showed that about 27% of participating consumers preferred foods from circular systems. As in the previous study, the results highlighted the importance of consumers' environmental attitudes in determining their preferences for environmentally sustainable products. All of the above results on consumers allow us to suggest to governments, policy makers and other sectors involved in sustainable food production, the standardization of food labels obtained through circular agriculture systems and the design of educational programs to increase knowledge about the problems generated by unsustainable consumption habits.
  
• PAZMIÑO FLORES, YADIRA CARMEN: Evaluación de los usos de suelo y valor ecosistémico del páramo de la Subcuenca Chambo (Ecuador)
  
  Author: PAZMIÑO FLORES, YADIRA CARMEN
  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 SUSTAINABILITY
  Department: University Research Institute for Sustainability Science and Technology (IS.UPC)
  Mode: Article-based thesis
  Deposit date: 17/04/2024
  Reading date: 23/07/2024
  Reading time: 11:00
  Reading place: ETSECCPB, Sala Conferències C2-212 (C/Jordi Girona 1-3, mòdul C2, Campus Nord, Barcelona).
  Thesis director: FELIPE BLANCH, JOSE JUAN DE | VALLBE MUMBRU, MARC
  Committee:
       PRESIDENT: AGUILERA BENAVENTE, FRANCISCO
       SECRETARI: ALCARAZ SENDRA, OLGA
       VOCAL: GUAITA PRADAS, INMACULADA
       VOCAL NO PRESENCIAL: HERNÁNDEZ CLEMENTE, ROCÍO
       VOCAL NO PRESENCIAL: GILABERT NAVARRO, M. DESAMPARADOS
  Thesis abstract: The scarcity of information that allows understanding the importance of natural resources from an economic approach is a limitation to establish parameters related to environmental investment in conservation plans. This research proposes a methodology that allows modeling the variability of páramo land uses and the Ecosystem Valuation (EV) of the Chambo-Ecuador sub-basin from a bioeconomic monitoring that links the economic rent of páramo land uses with remote sensing tools and geographic information systems. The main results of the methodology determined that temporal monitoring of land covers is essential to identify areas of greatest vulnerability to EV degradation. The thresholds, functions and interrelationships determined in the Cart Decision Tree (CDT), Multilayer Perception (MLP), Multivariate Adaptive Regression Splines (MARS) and Support Vector Machines (SVM) models for land cover recognition were efficient; the models performed 88%, 85%, 83% and 81% respectively. The hybridization of the models, Markov chains and cellular automata was appropriate for predicting future land cover changes in Andean areas in relation to their VE, the methods achieved acceptable accuracy for recognizing páramo land uses. The variables chosen for land cover classification were adequate to identify land cover particularities.The opportunity cost and benefit transfer methods proposed obtained a good performance in the evaluation of food production trajectories linked to environmental services (ES) of carbon supply and concentration associated with indirect and support ES, so it was determined that the information from the dynamics of environmental services is an important indicator to understand the real state of the resource and consequently allows understanding the necessary strategies to undertake sustainable actions for ecological management.The mapping generated allowed us to determine that the páramo decreased by 13% between 2000-2010 and 19% between 2010-2020. It was estimated that the loss of the ecosystem between 2000 and 2030 will increase to 28%. From the first year of the study to the last year considered in the work, the páramo will go from occupying 92% to 64% of the area studied. The changes in the EV reveal that the categories with anthropogenic activity analyzed maintain a constant growth that has a direct impact on the EV of the páramo. The most affected areas are those up to 3500 meters above sea level. The EV of the Chambo sub-basin from 2000 to 2020 will increase from 2.86×108 USD to 2.59×108 USD and it is estimated that by 2030 the EV will decrease to 2.48×108 USD, which leads us to recognize that, although the loss of the EV of the natural resource is not critical, its degradation is increasing.Through this methodology it will be possible to obtain, in a practical way, data on the conservation status of the resource over time, allowing to solve problems related to the scarcity of data and leading to the understanding of changes in the area from a socioecological approach, i.e., covering the environmental impacts of human activities on natural systems. The basis of the developed method allows replication of the methodology.The information generated by this study will be of vital importance to understand the causes of the changes in the Andean systems in monetary and environmental terms, which will allow the development of management plans and conservation policies aimed at protection and sustainable management from an economic approach.
  
• RAMIREZ GARRIDO, ROSEMBER: Evaluación del Riesgo Ambiental de las Nanopartículas de Plata (AgNPs) en Ecosistemas Acuáticos
  
  Author: RAMIREZ GARRIDO, ROSEMBER
  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 SUSTAINABILITY
  Department: University Research Institute for Sustainability Science and Technology (IS.UPC)
  Mode: Normal
  Deposit date: 18/04/2024
  Reading date: 10/06/2024
  Reading time: 11:00
  Reading place: ETSEIB (Sala de audiovisuales del pavellón G, 2 planta, Campus Sud, Barcelona). Avda. Diagonal, 647
  Thesis director: DARBRA ROMAN, ROSA MARIA | MARTI GREGORIO, VICENÇ
  Committee:
       PRESIDENT: DE PABLO RIBAS, JOAN
       SECRETARI: SANCHÍS SANDOVAL, JOSEP ÀNGEL
       VOCAL: DÍAZ CRUZ, SILVIA
  Thesis abstract: The widespread and increasing use of silver nanoparticles (AgNPs) in various products is leading to their release into different environmental compartments, especially into aquatic environments. These particles can enter these environments through various pathways, for example, gradually via effluents from wastewater treatment plants (WWTPs) or accidentally through spills onto soil or into rivers. This thesis presents a detailed analysis of the transport (advection-dispersion) and dispersion of silver nanoparticles (AgNPs) in both surface and groundwater, considering mass balances, various mathematical models, and factors influencing their mobility and retardation. For surface waters, continuous and point discharges are considered, and an analytical model is used to represent the behavior of AgNPs in the river. For groundwater, point discharges are considered. The interaction of AgNPs with porous media in groundwater (retardation process) is also taken into account, which allows for the calculation of the maximum concentration of AgNPs in groundwater. Initially, a Fuzzy Logic model is developed to assess the environmental risk in aquatic ecosystems based on the concentration and toxicity of AgNPs. The toxicity is determined with great adaptability by including variables such as shape, size, and coating of the nanoparticles, allowing a more accurate risk assessment. This model is applied to a discharge of AgNPs into the river from WWTP effluents or an accident. The results show that in all cases, the risk of AgNPs due to direct accidental discharge into the river poses a higher risk than that from WWTPs. Subsequently, a hybrid model is developed that integrates Monte Carlo simulation (for concentration calculation) with the developed Fuzzy Logic model. This integration provides a tool for assessing the environmental risk of AgNPs due to a spill onto the soil. Two scenarios are proposed after the spill: discharge of AgNP-contaminated aquifer water into the river and use of this aquifer water for wetland recharge. The concentration distribution of AgNPs by river discharge is below the proposed legal limit, while in the wetland use scenario, legal limits are not met in any case, indicating a higher risk associated with this latter use. After conducting a sensitivity analysis, it has been proved that the developed Hybrid model, which combines Fuzzy Logic and Monte Carlo techniques, is a useful and versatile tool for managing uncertainty in risk assessment.
  

DOCTORAL DEGREE IN URBANISM

• KARAMANEA, PANAGIOTA: Diachronic terrains: Three landscape narrations on the west Attic coast
  
  Author: KARAMANEA, PANAGIOTA
  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 URBANISM
  Department: (DUTP)
  Mode: Normal
  Deposit date: 23/04/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: SABATE BEL, JOAQUIN | GOULA, MARIA
  Committee:
       PRESIDENT: SARDÀ FERRAN, JORDI
       SECRETARI: SPANOU, IOANNA
       VOCAL: MORAITIS, KONSSTANTINOS
  Thesis abstract: The thesis researched for a hybrid interdisciplinary system of tools that could help decode coastal landscapes. The west Attic shoreline, a space of contrasts and surprises, stands as a forgotten landscape awaiting rediscovery. Amidst the interplay of urbanity and landscape Attica, unfolds dynamic perspectives as a cultural ecotone. Until now, a comprehensive cartographic study of the western Attic coast, has been absent. The research delves into the cultural formation of perspectives on the coast, examining how both foreign and local intellectuals have shaped these views over time. It investigates the Grand Tour and its contemporary interpretations, the 1930¿s, seeking to understand their influence on the collective imagination regarding Attica. It provides a synthesized overview of the historical aspect, spanning from antiquity to the touristic evolution of today. The research navigated through toponymy and landscape, historical archives and old maps focusing especially on the west Attic coastal terrain. The research also endeavors to adopt the lens of the seventh art, cinema. The research explores the sensorial gaze Attica and the local cinema 1950¿s selection of coastal shots. From a cultural and sensory standpoint, cinema offers a unique lens through which the coast is perceived. It allows to explore the emotional and experiential aspects of coastal life, capturing the essence of the seaside environment. Cinema, with its storytelling capabilities can help us connect with the coast on a personal and emotional level. By dissecting films where the landscape takes on a protagonist role, the research shifts its focus to cinema as a tool for articulating the intricacies of the coastal environment ¿ a novel and imaginative approach to apprehending its essence. In this context, cinema is not merely regarded as a narrative artistic form; rather, it emerges as a potent medium for both representation and comprehension. Finally, the thesis delves into an exploration of the landscape through original mapping and cartography, aiming to uncover dynamics and qualitative attributes. The overarching goal is to dissect the coastal expanse, unravelling its configuration, fundamental traits, and prominent landscape elements. Through cartography, an effort is made to discern the intricate relationships between various entities, navigating scales and offering an interpretive lens grounded in landscape perspective. On the other hand, the morphological and cartographical approach involves an examination of the physical characteristics and spatial layout of the coast. This includes the topography, land use patterns, and geographical features that shape the coastal region. By delving into these aspects, a deeper understanding of how the coast functions is gained and how it can be harnessed for various purposes, from urban landscape planning to environmental conservation. The spatial configuration of the ground, the surface as infrastructure in the sense of landscape armature and ecological aspects seen as a systemic network, could help integrate the natural landscape in the discussion of rejuvenating the city in a resilient way. Landscape architecture as an interface between city and nature is proposing interdisciplinary processes to apply.