Doctoral School

Theses authorised for defence

DOCTORAL DEGREE IN AEROSPACE SCIENCE AND TECHNOLOGY

  • ATHOTA, RATHAN BABU: Numerical Analysis of Thermally-Driven Winds in Mountain-Valley Regions
    Author: ATHOTA, RATHAN BABU
    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: 14/06/2024
    Reading date: 19/09/2024
    Reading time: 10:00
    Reading place: Aula 309/310, Edifici C3, EETAC - Campus Baix Llobregat (Castelldefels) / https://meet.google.com/wwn-ciea-cfz
    Thesis director: DE VILLARDI DE MONTLAUR, ADELINE | ROJAS GREGORIO, JOSE IGNACIO
    Committee:
         PRESIDENT: JIMÉNEZ CORTÉS, MARIA ANTONIA
         SECRETARI: GONZÁLEZ HORCAS, SERGIO
         VOCAL: YANG, LIN
    Thesis abstract: This thesis aims at simulating thermally-driven winds in mountain-valley systems, using the open source computational fluid dynamics (CFD) software OpenFOAM. Thermal-driven winds occur in mountain-valley regions due to temperature gradients induced by the lower atmosphere’s diurnal heating-cooling cycle. The contemporary energy market is particularly interested in thermal-driven winds since they exhibit greater regularity and periodicity than synoptic winds and thus can be more predictable. In the first phase of this research, the Reynolds Averaged Navier-Stokes k–ε turbulence model is validated on a 3D geometry by comparing its results to large-eddy simulations described in the literature. Then, a computational model of an idealised 2D mountain-valley configuration is created to mimic thermally-driven winds. In this work, the most suitable top surface boundary conditions (BC), field temperature, and pressure initial conditions (IC) are examined. A transient solver is used to address the buoyant, turbulent flow of incompressible fluids. In contrast to traditional mechanisms of convection of fluid flows associated with pressure gradients, buoyancy is the driving force of convection of the studied thermally-driven flows. In this work, temperature is linearly dependent on altitude, which is imposed as BC on the mountain slope, resulting in thermally-driven wind generation. The minimal computational domain height required to successfully replicate thermally-driven winds is also explored, as are the effects of altitude-dependent and altitude-independent IC on the results. In particular, slip-wall BC on the fluid domain’s top surface and constant temperature IC were found to be the best options because slip-wall BC has produced results which are in good agreement with LES models, whereas constant temperature IC has simulated neutrally stratified atmospheric boundary layer flows. The proposed numerical setup has accurately recreated the typical flow velocity patterns along the slope. The impact of the valley width on the anabatic (up-slope) and katabatic (down-slope) flow behaviour was also examined. Although increasing the valley width has no substantial effect on the thermally-driven flow velocity (along-slope), it does cause a displacement of the position of the associated convective cell. The influence of the roughness length on the flow behaviour is explored by varying the needed computational domain height. Comparing the effect of different values of roughness lengths as well as comparing uniform and nonuniform sand grain roughness is performed. The effect of the temperature diurnal cycle on the thermally-driven winds is also explored. Then, this research also examines how the mountain slope angle affects the along-slope flow velocity, slope-normal velocity, and turbulent kinetic energy. Finally, a wide range of numerical simulations allow to investigate the influence of various wall functions on modelling thermally-driven flows. To sum up, it is concluded that CFD models can replicate the challenging atmospheric boundary layer flows with sufficient accuracy, which can help in determining the most suitable wind turbines for specific sites in mountainous regions.
  • BUITRAGO LEIVA, JEIMMY NATALY: Contributions to Eco-Friendly Satellite Lean Design for a Sustainable Space Environment
    Author: BUITRAGO LEIVA, JEIMMY NATALY
    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: 10/07/2024
    Reading date: 16/09/2024
    Reading time: 15:00
    Reading place: Sala de juntes. Edifici D4
    Thesis director: CAMPS CARMONA, ADRIANO JOSE
    Committee:
         PRESIDENT: ALIAKBARGOLKAR, ALESSANDRO
         SECRETARI: GUTIERREZ CABELLO, JORGE LUIS
         VOCAL: ULLOA SANDE, CARLOS
    Thesis abstract: Currently, half of the satellites do not reach 20% of their expected lifetime. The possibility of recycling these "zombie satellites" (ZS) with limited capabilities would optimize this on-orbit infrastructure, reducing unnecessary launches and being more cost-effective. A 12U CubeSat costs around €2.5 million to manufacture and launch. In this way, there would be no need to launch new satellites for new missions, resulting in positive environmental and economic impacts. This research proposes an ecological approach to satellite design and operation, integrating space sustainability strategies and green practices within the NewSpace paradigm. For a comprehensive analysis of the satellite lifecycle, eco-friendly and lean manufacturing characteristics need to be integrated. This concept aims to consolidate efforts towards a sustainable space and considers innovative technologies for standard satellites.This doctoral thesis undertakes a research study and practical experiences focused on small satellites, divided into 6 parts with 12 chapters.The first part, with two chapters, introduces space sustainability and the Eco-LeanSat concept, emphasizing a sustainable approach to satellite manufacturing and the reuse of capabilities after failure. It addresses the evolution of smallsat capabilities and institutional efforts to promote sustainability strategies.The second part, comprising two chapters, deals with proposals for reusing satellites that have failed in orbit. Chapter three analyzes the most common failures in smallsats and proposes mission design to reuse these capabilities and prevent them from becoming space debris. Chapter four studies the causes of failures arising from the space environment.The third part proposes agile methodologies, Lean Six Sigma, and Model-Based System Engineering (MBSE) software for satellite manufacturing, applied to NanoSat Lab missions: 3Cat-4 and 3Cat-8, and the Colombian mission 3ColStar. Chapter five applies Lean Six Sigma to the 3Cat-8 mission, identifying bottlenecks and optimizing execution. Chapter six presents the preliminary design of the 3ColStar mission, incorporating MBSE software. Chapter seven develops algorithms for the Attitude Control System in the 3Cat-8 mission. Chapter eight performs thermal analysis of the 3Cat-4 mission.The fourth part, with chapter nine, addresses legal considerations for future sustainable missions, highlighting the lack of specific regulations for satellite reuse in orbit. Chapter ten proposes future studies with a sustainability focus.The fifth part includes appendices of the mentioned chapters, and the sixth part lists publications and other academic activities conducted during the doctoral study

DOCTORAL DEGREE IN ARCHITECTURAL DESIGN

  • GONZÁLEZ TORRADO, CRISTIAN: Aspectos ambientales en la Casa Aversú de Alejandro de la Sota: El proceso del proyecto
    Author: GONZÁLEZ TORRADO, CRISTIAN
    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 ARCHITECTURAL DESIGN
    Department: Department of Architectural Design (PA)
    Mode: Normal
    Deposit date: 01/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: VALOR MONTERO, JAUME
    Committee:
         PRESIDENT: RAVETLLAT MIRA, PEDRO JUAN
         SECRETARI: BLANCO GRANADO, JAIME
         VOCAL: PRIETO GONZALEZ, EDUARDO ANTONIO
         VOCAL: PASCUAL RUBIO, ANA
         VOCAL: DEVESA DEVESA, RICARDO
    Thesis abstract: This research stems from two personal interests: climate awareness and Alejandro de la Sota. Based on this premise, the aim of the research is to find the connection between environmental aspects and architecture, particularly in the project process. Thus, the research will be used to answer the question:At what moments and in what ways do environmental aspects influence architectural form?To achieve this, the present investigation will analyze Sota's Casa Arvesú, structuring its study into four parts.The first part addresses the concept of environmental aspects, establishing the vocabulary to be used. The objective of this first part is to return to the origin of the concept and review current stances regarding the impact of environmental decisions on the project, aiming to move away from clichés and redefine architecture as a medium rather than a mere support for environmental solutions. At the end of this first section, the linkage of environmental aspects with Alejandro de la Sota will also be discussed.The second part pertains to the descriptive study of the house. It involves an exploration of the national and international context at the time of its conception and construction. Additionally, the work is recognized within Alejandro de la Sota’s professional trajectory. The house is then characterized in terms of use, location, and technique throughout the project process, analyzing its various versions—sketches—until reaching its final form.The third part pertains to the analytical study. For this, a “digital twin” of the work—demolished in 1987—has been created, allowing for the quantification of environmental impacts in terms of geometry, light, systems, or energy and fluid dynamics checks of the house. The objective of the digital model is the numerical verification of what Alejandro de la Sota applied empirically. From this starting point, the solutions are initially categorized as systems and then the house is examined through five characteristic actions that relate the work to environmental aspects. The five categories are as follows:- Elevate, densify, and distance [as implantation]- Permeate, settle, and plant [as appropriation of the environment]- Contrast, flow, and culminate [as program]- Shield, project, and extend [as definition of limits]- Shade, ventilate, and retain [as passive strategies]Finally, this third part concludes with the identification and incorporation of environmental objectives in the project, using a graph that transversally relates the design process.The fourth part corresponds to the conclusions of the research. That is, the answer to the question that initiated this research in four phases:- Characterization of the environment, the user, and the problem.- Formulation of objectives.- Establishment of the internal structure of the project.- The “effort to reduce effort.”
  • TERÉS CASTÁN, JUDITH: La repetición en un modelo habitacional urbano: De las terraced houses londinenses tardogeorgianas a los apartment houses neoyorquinos de la Era Metropolitana
    Author: TERÉS CASTÁN, JUDITH
    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 ARCHITECTURAL DESIGN
    Department: Department of Architectural Design (PA)
    Mode: Normal
    Deposit date: 25/06/2024
    Reading date: 26/07/2024
    Reading time: 11:30
    Reading place: ETSAB - Planta Baja - Sala de Grados
    Thesis director: GONZALEZ RAVENTOS, AQUILES | GARCIA ESCUDERO, DANIEL
    Committee:
         PRESIDENT: NAVARRA, MARCO
         SECRETARI: RUBERT DE VENTOS, MARIA
         VOCAL: MORAGAS SPA, ANTONIO
         VOCAL: LLORACH HERRERO, ENRIC
         VOCAL: FREDIANI I SARFATI, ARTURO
    Thesis abstract: Domestic architecture is the backbone of the historic city due to its ambivalent capacity, expressed in urban housing models, of providing the citizens habitat at the same time of contributing to plot the texture, to structure the morphology and to define the urban identity.The research of two a priori disparate models, the that of the late Georgian London terraced houses and that of the New York apartment houses of the "Metropolitan Era", between which, however, a formal parallelism can be detected, had made possible to expose where the essentiality of architectural repetition lies in the definition of an urban housing model. The establishment of a repetitive canon is sine qua non condition for its configuration and prevalence; so that, when the repetition is objectified and applied to practice, it appears implicit in the design codes that govern the model. It is found that the repetition covers three magnitudes: the big scale, which considers the implementation in the city; the intermediate scale, of typological nature, which contains the different typologies which make up the model; and the smaller scale of detail, that focuses the attention on those architectonic elements that, with a similar design, are regularly repeated. The result is an urban landscape in which architectural uniformity prevails, given by the rhythmic sequence that provides the city with the orderly repetition of certain parameters linked to domestic architecture; A precious, although sometimes forgotten, uniformity that allows the urban maelstrom to be calmed down and that architecture that has to be highlighted singularizes.In order to an urban housing model will become established and it persisted along the time, the repetitive canon which configures it must admit a certain degree of transgression, of flexibility in front of the different social and design conditions that may be required in each one of uncountable dwelling units that conform it. An urban housing model, governed by a repetitive canon with capacity of adaptability, could even be extrapolated contextually; as the thesis demonstrates with the translation of the model of the sober and elegant London terraced houses to New York, where after an adaptation process, including a scalar magnification, it was transformed into the model defined by the magnificent apartment houses built around Central Park during the final decades of the nineteenth century and the early twentieth century.

DOCTORAL DEGREE IN ARCHITECTURAL, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY

  • ORTEGA DONOSO, SARA ISABEL: Luz y aprendizaje dentro de los espacios educativos. Aproximaciones desde el color.
    Author: ORTEGA DONOSO, SARA ISABEL
    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 ARCHITECTURAL, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY
    Department: Department of Architectural Technology (TA)
    Mode: Normal
    Deposit date: 01/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: MUROS ALCOJOR, ADRIAN | BAUTISTA PEREZ, GUILLERMO
    Committee:
         PRESIDENT: ESCOFET ROIG, ANNA MARIA
         SECRETARI: DAUMAL DOMENECH, FRANCESC DE PAULA
         VOCAL: HIGUERA TRUJILLO, JUAN LUIS
    Thesis abstract: We live in a visually demanding environment. Most of our cognitive stimuli come from visual perception. In this context of widespread dependence on the sense of sight, studying the link between artificial light and cognitive tasks is key to interacting with our memory and attention, which are increasingly accustomed to dynamic environments.The objective of this research is to analyze the disciplines that can most influence learning: cognitive sciences, architecture, and education, to:First, analyze how some light parameters can affect learning, paying special attention to the impact of light on human perception and attention and how these affect memory.Next, analyze innovative teaching methodologies and how communication and learning technologies have been incorporated into the classroom.Finally, examine the evolution of educational spaces through case studies of schools worldwide over recent decades, delving into the ways lighting and control technologies have been integrated according to the needs of educational methods within the classroom.From the analysis of the implications of light on attention and memory, we will derive the possibilities that working with different light parameters in the classroom offers us; from the analysis of teaching methodologies, we will obtain the real needs of the current classroom; and from the case study analysis, we will gain the capacity for innovation in the classroom with new lighting strategies.The intersection of these three disciplines results in three alternative uses of lighting in educational spaces, which are subjected to an experimental analysis comparing performance on a task in the proposed scenes with performance under traditional lighting conditions to conclude new classroom solutions and future lines of research.A broad narrative review methodology has been used for the case studies, providing an overview of the problem of adapting lighting to usage and users within schools. To this end, sources published in architectural journals and significant examples with educational spaces that develop innovative teaching methodologies have been reviewed, and criteria for analyzing natural and artificial lighting considered throughout these cases have been established.An experimental methodology has been used to analyze the impact of three alternative lighting proposals based on situations not previously considered. In all three cases, a control group and a study group from two public schools in the province of Barcelona are considered. These proposals arise from the observation of a lack of consideration of an important light parameter in the transmission of information in a visual environment: color.Finally, the results reflect the need to adapt and make classrooms more flexible according to the different learning needs within the classroom and the possibility of doing so with proposals not previously considered regarding color and dynamism parameters.
  • PERALTA COELLO, ANGÉLICA BRIGITTE: El hábitat rural y las posibilidades de intervención. Estrategias para la mejora de las viviendas rurales vernáculas en la región Costa de Ecuador.
    Author: PERALTA COELLO, ANGÉLICA BRIGITTE
    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 ARCHITECTURAL, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY
    Department: Department of Architectural Technology (TA)
    Mode: Normal
    Deposit date: 08/05/2024
    Reading date: 05/09/2024
    Reading time: 15:30
    Reading place: Sala Beta". ETSAB. Main floor - Public link for the videoconference: meet.google.com/tyu-ivde-kba
    Thesis director: PALUMBO FERNANDEZ, MARIANA | GIRALDO FORERO, MARIA DEL PILAR
    Committee:
         PRESIDENT: RINCÓN VILLARREAL, LÍDIA
         SECRETARI: BOSCH GONZÁLEZ, MONTSERRAT
         VOCAL NO PRESENCIAL: LOPEZ ANDRADE, JAIME EDUARDO
         VOCAL NO PRESENCIAL: COMPTE GUERRERO, FLORENCIO ANTONIO
    Thesis abstract: Vernacular homes in Ecuador have progressively fallen into disuse despite being affordable constructions, quick to build and perfectly integrated with the environment, due to various social, economic, and cultural factors. It is proposed to analyze the conditions of habitability and materiality of rural homes built with vernacular techniques in the Coastal region of the country. Although 37% of the population resides in rural areas, rural housing has received little attention. The lack of information on housing models suitable for this population is evident, so this study aims to analyze the most relevant characteristics of traditional rural housing in relation to its location and the materials available in the environment. The country's housing conditions are examined, considering both the natural factors that influence architecture and the socioeconomic characteristics of the communities, highlighting the interaction between the natural environment and built structures. Through a detailed survey of ninety homes and the organization of the information collected through files, the aim is to reflect the detailed universe of the homes in their different areas and highlight the diversity of architectural types and construction techniques used in each area, as well as the architectural wealth of the region. In addition, the restrictions and challenges associated with the use of materials of natural origin compared to the predominant adoption of industrialized materials are explored. For the processing of the information obtained, an identification and analysis tool were developed that allows us to propose specific construction and conservation strategies, and based on the results, improve the application techniques and traditional materials that allow us to overcome the negative perception that exists towards them and promote their sustainable use in contemporary architecture.In addition to addressing the national production of the scope of study, cases from other regions of the planet with similar characteristics are also analyzed with the purpose of extracting lessons applicable to the Ecuadorian context through the interpretation of the results obtained, allowing the development of strategies for the preservation and promotion of vernacular architecture in a changing and globalized context. Finally, the implications of the research are discussed, and fundamental conclusions are offered about vernacular architecture in the coastal region of Ecuador, reflecting on the importance of preserving cultural identity and ancestral knowledge in the construction of sustainable and socially integrative homes, promoting construction practices. that respect and celebrate the cultural and environmental diversity of Ecuador. It is not intended to propose a specific housing model, but rather to offer strategies that allow these aspects to be considered in the development of sustainable, functional housing models in accordance with their context.

DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION

  • FLORES VÁZQUEZ, CARLOS ALBERTO: CeCi: Design, Development and Validation of an Affordable Consumer Service Robot as a Social Robot
    Author: FLORES VÁZQUEZ, CARLOS ALBERTO
    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 AUTOMATIC CONTROL, ROBOTICS AND VISION
    Department: Department of Automatic Control (ESAII)
    Mode: Normal
    Deposit date: 02/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: ANGULO BAHON, CECILIO
    Committee:
         PRESIDENT: VALLÈS PERIS, NÚRIA
         SECRETARI: REPISO POLO, ELY
         VOCAL: TREJO RAMÍREZ, KARLA ANDREA
    Thesis abstract: This research discusses elements to be considered for designing, developing, and validating a service robot that performs its task in different social environments. Due to the social focus of the provided services, technical considerations are demanded toaccomplish the task, and the acceptability of use for the people interacting with the robot.The first stage of the research considers previous cases on the implementation of service mobile robots, their analysis, and the motivation of how to solve their acceptability and use by people. The developmental part presents the technical and social considerations for implementing the CeCi (Computer Electronic Communication Interface) social robot. Two main problems of social robots and service robots in social environments currently on the market are addressed, which are the main focus of this research: First, their costs are not affordable for many companies, universities, or individuals in developing countries. The second is that their design is exclusively oriented to the functional part with a viewpoint inherent to the engineers who create them without considering the end users’ views, preferences, or requirements, especially for their social interaction. This last reason ends up causing a certain aversion to the use of this type of robot.In response to the issues raised, an affordable, low-cost prototype is proposed, starting from a commercial platform for research development and using open-source code. The robot design presented here is centered on the criteria and preferences of the end user, prioritizing acceptability for social interaction. This document details the selection process and hardware capabilities of the robot. Moreover, a programming section is provided to introduce the different software packages used and adapted for social interaction, the main functions implemented, as well as the new and original part of the proposal. A list of applications currently developed with the robot and possible applications for future research are discussed.As a final step, the complete implementation of the social robot is explained based on two design elements. The first element is the use of the design thinking methodology for the development and implementation of the robot. The second element, of a technical nature, is a previous taxonomy generated for defining socially-aware robot assistants. Therefore, in the construction process, special emphasis is placed on the realization of prototypes and their adjustment to the users’ preferences. Interviewswith users who were unaware of the robot’s capabilities were used to improve and validate the prototype. These prototypes and their evolution will be presented based on the adjustments performed. Beyond the users’ feedback, previous experiences exposed to the state of the art were considered for the evolution of this robot. The entire methodological process is validated with surveys, and results are presented as a SWOT (strengths, weaknesses, opportunities, and threats) analysis for future improvements.
  • WANG, CHUANSHENG: Research on signal and image denoising techniques
    Author: WANG, CHUANSHENG
    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 AUTOMATIC CONTROL, ROBOTICS AND VISION
    Department: Department of Automatic Control (ESAII)
    Mode: Normal
    Deposit date: 03/07/2024
    Reading date: 30/07/2024
    Reading time: 11:00
    Reading place: Sala de Juntes de la Facultat de Matemàtiques i Estadística (FME), Carrer de Pau Gargallo, 14, 08028 Barcelona
    Thesis director: GRAU SALDES, ANTONI | GUERRA PARADAS, EDMUNDO
    Committee:
         PRESIDENT: PALACÍN ROCA, JORGE
         SECRETARI: SANFELIU CORTES, ALBERTO
         VOCAL: RIBAS XIRGO, LLUÍS
    Thesis abstract: This dissertation aims to investigate two crucial tasks in the field of signal and image processing: signal denoising and image enhancement. Firstly, for signal processing, we propose three innovative denoising algorithms tailored specifically for one-dimensional EEG signals. These algorithms combine the strengths of deep learning and traditional signal processing techniques to effectively adapt to various noise types associated with different cognitive tasks, thereby enhancing the quality and accuracy of the signals. Secondly, in the domain of image processing, we introduce three novel image enhancement algorithms designed to tackle multiple noise types in natural scenes. By integrating deep learning methodologies with prior knowledge, these algorithms enhance image sharpness, contrast, and detail reproduction, demonstrating adaptability and reliability across different lighting, weather conditions, and photographic equipment. Lastly, we conduct a comprehensive analysis of the similarities and differences between image enhancement and signal denoising tasks. Through comparing the methodologies employed by each in handling diverse noise types, we derive meaningful conclusions to guide future research. These contributions are poised to significantly advance technological capabilities and theoretical understanding in both domains.

DOCTORAL DEGREE IN COMPUTER ARCHITECTURE

  • 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: Department of Computer Architecture (DAC)
    Mode: Normal
    Deposit date: 30/04/2024
    Reading date: 26/07/2024
    Reading time: 11:00
    Reading place: Sala d'Actes FIB - Edifici B6 - Campus Nord - Barcelona
    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.
  • KOSTALAMPROS, IOANNIS - VATISTAS: Post-quantum cryptography acceleration for next generation computers
    Author: KOSTALAMPROS, IOANNIS - VATISTAS
    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: Department of Computer Architecture (DAC)
    Mode: Normal
    Deposit date: 14/06/2024
    Reading date: 13/09/2024
    Reading time: 10:30
    Reading place: Sala E101 - Edifici C6 (FIB) - Campus Nord - Barcelona
    Thesis director: MORETÓ PLANAS, MIQUEL | HERNANDEZ LUZ, CARLES
    Committee:
         PRESIDENT: CANO REYES, JOSE
         SECRETARI: MARTORELL BOFILL, XAVIER
         VOCAL: TSOUTSOURAS, VASILIOS
    Thesis abstract: The security of modern cryptographic schemes relies upon mathematical problems that are assumed to be hard to solve, like the Rivest-Shamir-Adleman (RSA) problem or the discrete logarithm problem over elliptic curves. Using the existing “classical” computers, all known algorithms attempting to solve these problems, would require such a big amount of computational time that will actually make the intercepted data useless by the time the attack finishes.Around 1997, Shor and Grover independently developed efficient quantum-computer algorithms that can give unprecedented speedup on certain mathematical problems. It then became evident that the advent of a large scale quantum computer can jeopardize secure communications. Nevertheless, it is still not clear whether there will exist large scale quantum computers able to break the current public key cryptographic standards. As a preemptive act, the National Institute of Standards and Technology (NIST) announced in 2015 its plans for transitioning to Post-Quantum (PQ) cryptographic algorithmic standards. The widespread adoption of the current standards , calls for further research on the efficiency and security of the PQ standards implementation on modern computing systems.This thesis intends to bridge the gap between the PQ cryptosystems’secure specification and their respectively secure and efficient implementation in advanced computing architectures.We specifically choose the PQ cryptosystem of Classic McEliece (CM), merely due to its long-standing security. CM has withstood attacks with minor modifications since its inception in 1978 and is currently a finalist of the NIST contest and has already been integrated in commercial products like VPN networks.This thesis comprises four main contributions. In the first one we present a hardware/software (HW/SW) co-design acceleration of the CM cryptosystem. The second contribution is geared towards the design and integration of custom designed and monolithic CM accelerators in a RISC-V based SoC. The third contribution strives to further optimize the performance of CM in hardware by introducing an advanced design of a monolithic accelerator for the encryption part of the CM cryptosystem. The final contribution of this thesis is moving away from a monolithic hardware accelerator and investigates the impact of vectorization by an SIMD unit on the CM application.With this thesis, we conclude a study conveyed on the CM cryptosystem, concerning its efficient hardware implementation on modern computing infrastructures. Nevertheless, there are numerous future research directions that could build on the knowledge gained as well as the hardware infrastructure designed in the context of this thesis. As such, we consider the secure implementation and side-channel mitigation on the CM hardware accelerators themselves and the performance evaluation of lightweight hardware implementations of CM.
  • LEDOUX, LOUIS EDUARDO YVES: Floating-point arithmetic paradigms for high-performance computing: software algorithms and hardware designs
    Author: LEDOUX, LOUIS EDUARDO YVES
    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: Department of Computer Architecture (DAC)
    Mode: Normal
    Deposit date: 03/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: CASAS GUIX, MARC
    Committee:
         PRESIDENT: PETIT, ERIC
         SECRETARI: MARTORELL BOFILL, XAVIER
         VOCAL: GARCIA, RÉMI
    Thesis abstract: This dissertation explores the challenges and advancements in arithmetic representations and computations within computer architectures, focusing on the limitations of the IEEE 754 standard.Modern computing demands, driven by advancements in AI, HPC, and scientific simulations, make efficient and precise numerical representations crucial. This work investigates these challenges and proposes innovative solutions, evaluating their impact on computational efficiency and accuracy.The core problem is the inefficiencies of the IEEE 754 standard for floating-point arithmetic, which do not meet the needs of modern workloads. These inefficiencies result in higher energy consumption, inadequate precision, and suboptimal performance, especially in energy-constrained environments and high-precision applications.To address these challenges, this thesis explores various facets of arithmetic computation, from algorithmic concepts to metal and silicon structures. It introduces mechanisms to improve the adaptability of numerical representations, allowing precision adjustments according to computational tasks, resulting in more efficient circuits. Focusing on improving arithmetic performance, the thesis addresses energy consumption and highlights the importance of efficient arithmetic logic units. It also shows how these solutions can be integrated into various software frameworks, revealing a correlation between numerical requirements and internal precision, highlighting an underexploited aspect of general-purpose floating-point formats.Firstly, it develops a framework for generating Posit operators in hardware, improving accuracy and performance in tasks like image classification. The Posit Operator Framework, described in SystemVerilog, enables the construction of Multi-Layer Perceptrons for inference engines, applicable in POWER9/CAPI2 environments with FPGA acceleration.Secondly, it presents a generator for Systolic Arrays optimized for Matrix-Matrix Multiplication (MMM), showing the impact of custom hardware configurations on accuracy and energy efficiency. The MMM units are fully parametrizable and adapted to the numerical specifications of the workload, facilitated by a core generator with automated pipelining. These units allow evaluations with CAPI2 on FPGA and POWER9 systems, achieving up to two Tera floating-point operations per second. They have also demonstrated success in ASIC generation.Additionally, it establishes an open-source framework to integrate MMM units into high-level software, offering energy savings and enhanced precision for applications like AI and scientific computations. The methodology involves mapping General Matrix-Matrix Multiplication calls in BLAS libraries to our accelerators via the OpenCAPI coherent link, saturating the 22 GBps bandwidth by tuning computer formats to accommodate more Processing Elements while preserving accuracy.Finally, the resurgence of vector processing leads to a reevaluation of division algorithms, revealing opportunities to use smaller and slower computing units, allowing more units within varied energy and power budgets. This approach shows a broad Design Space Exploration. We developed an open-source EDA ASIC flow, facilitating parallel generation of multiple chip designs, enabling systematic exploration of power, performance, and area across various process design kits to identify optimal configurations.These contributions form an interdisciplinary thesis that advances solutions to computing challenges from an arithmetic perspective, overcoming the "arithmetic wall."
  • SHARMA, ROBIN KUMAR: Parallelizing recurrent neural network and variants
    Author: SHARMA, ROBIN KUMAR
    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: Department of Computer Architecture (DAC)
    Mode: Normal
    Deposit date: 01/07/2024
    Reading date: 05/09/2024
    Reading time: 16:00
    Reading place: Defensa pública a la Sala E101 - Edificio C6 - FIB
    Thesis director: CASAS GUIX, MARC
    Committee:
         PRESIDENT: QUINTANA ORTI, ENRIQUE SALVADOR
         SECRETARI: ARMEJACH SANOSA, ADRIÀ
         VOCAL: VALLEJO GUTIÉRREZ, ENRIQUE
    Thesis abstract: Recurrent neural networks (RNN) have succeeded remarkably in various domains, such as Automatic Speech Recognition, Sentiment Analysis, time-series prediction, and Machine Translation. Despite their versatility, RNN poses significant challenges due to their complex internal structures, which impede the effective use of model parallelism. This often leads to a reliance on data parallelism to accelerate RNN performance. Furthermore, RNN demands extensive computational resources due to their large parameter counts. This doctoral research proposes innovative High-Performance Computing (HPC) strategies to optimize RNN deployment on CPUs, enhancing their efficiency in resource-limited settings. Through algorithmic improvements and memory-efficient techniques, this work seeks to maximize the potential of parallel computing for RNN, thereby transforming AI parallel system landscapes.This thesis introduces "Wavefront-Parallelization" (W-Par), which integrates model parallelism into unidirectional RNN to enhance inference and training on CPUs. W-Par utilizes fine-grained pipeline parallelism through wavefront computations, which are particularly effective for multi-layer RNNs on multi-core CPUs. These techniques allow for efficient workload distribution across parallel tasks while managing the dependencies of each RNN cell. Empirical results show that W-Par significantly outperforms existing implementations, achieving speed-ups of up to 6.6x times on contemporary multi-core CPU architectures, and maintains robust performance across various core and memory configurations without requiring source code modifications.Additionally, the thesis presents "Bidirectional-Parallelization" (B-Par), a novel execution model for Bidirectional Recurrent Neural Networks (BRNN). B-Par leverages inherent data and control dependencies in forward and reverse-order RNN in BRNN, dividing workloads efficiently across parallel tasks without needing layer-specific synchronization barriers. Tests on the TIDIGITS speech database and Wikipedia dataset demonstrate that B-Par significantly exceeds the performance of leading frameworks like TensorFlow-Keras and PyTorch, with speed-ups of up to 2.34x and 9.16x times, respectively, while maintaining accuracy.Finally, this thesis introduces the "Semi-Bidirectional RNN" (SB-RNN), a novel architecture that synergistically integrates the strengths of both unidirectional and bidirectional RNN. SB-RNN maintains the parameter count of unidirectional RNN while incorporating backward connections across layers to enhance the capability for information retention. This architecture enables SB-RNN to match and potentially exceed the accuracy of unidirectional RNN and bidirectional RNN (BRNN) across both CPU and GPU environments. Specifically, on the sentiment analysis task of the Stanford Sentiment Treebank (SST) dataset, SB-RNN demonstrates superior performance with 56.61% fewer parameters than their unidirectional counterparts, leading to a significant reduction in training time by 52.94%.Overall, this thesis introduces three advanced techniques: W-Par, B-Par, and SB-RNN - that significantly improve the efficiency and performance of RNN and BRNN models on multi-core CPUs and GPUs, facilitating enhanced processing across various applications without extensive code alterations.
  • TARANCO SERNA, RAÚL: Architectural strategies to enhance the latency and energy efficiency of mobile continuous visual localization systems
    Author: TARANCO SERNA, RAÚL
    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: Department of Computer Architecture (DAC)
    Mode: Normal
    Deposit date: 05/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: ARNAU MONTAÑES, JOSÉ MARÍA | GONZÁLEZ COLÁS, ANTONIO MARIA
    Committee:
         PRESIDENT: BEIVIDE PALACIO, JULIO RAMON
         SECRETARI: BARRADO MUXI, CRISTINA
         VOCAL NO PRESENCIAL: REDDI, VIJAY JANAPA
    Thesis abstract: The emergence of new applications such as autonomous machines (e.g., robots or self-driving cars) and XR (Extended Reality) promises to revolutionize how society interacts with technology in the rapidly advancing digital era. These technologies, deployed on edge devices, often rely on mobile or embedded SoCs (Systems-on-a-Chip) operating CV (Continuous Vision) pipelines that periodically capture and analyze environmental light.A typical CV SoC comprises two main components: a frontend for image capture and a backend for processing vision algorithms. The frontend usually includes an off-chip camera sensor and an ISP (Image Signal Processor), which processes the pixel stream, converting raw sensor data into high-quality images. The backend—comprising components such as the CPU, GPU, or specialized accelerators—analyzes the images stored in the main memory's framebuffer to extract perception insights and enable advanced decision-making.Existing research identifies visual localization, object detection, and tracking as the primary bottlenecks in these emerging applications. Those algorithms face two principal challenges when deployed in mobile CV systems: latency and energy consumption. For example, an XR headset uses visual localization to track head motion for accurate frame rendering, where latency can cause discomfort. In self-driving cars, localization ensures centimeter-level precision, with delays compromising safety, especially at higher speeds. Additionally, high energy consumption limits the operation of battery-powered mobile systems.This thesis embarks on a strategic journey to elevate mobile CV systems' performance and energy efficiency through several key contributions:We begin by analyzing a state-of-the-art visual localization engine on a CPU. The localization engine processes camera images, extracting and tracking features to estimate camera pose. Our evaluations reveal feature extraction as the primary bottleneck, accounting for 60% to 90% of total localization latency.Next, we investigate highly specialized hardware accelerator designs for image processing. The first contribution is LOCATOR (Low-power ORB Accelerator for Autonomous Cars), a hardware accelerator designed for ORB (Oriented FAST and Rotated BRIEF) feature extraction. LOCATOR processes image tiles with two parallel pipelines for feature detection and description, employing techniques like optimal static bank access patterns, caching mechanisms, and selective port replication. These optimizations yield a 16.8× speedup for ORB feature extraction, 1.9× end-to-end speedup, and 2.1× energy reduction per frame compared to a baseline mobile CPU.Realizing the need for more programmable and versatile solutions, our second contribution, SLIDEX (Sliding Window Extension for Image Processing), introduces a domain-specific vector ISA extension for CPUs. SLIDEX exploits the sliding window processing model, interpreting vector registers as overlapping windows to maximize data-level parallelism. SLIDEX reduces data access and movement, enhancing tasks like 2D convolutions and stencil operations, resulting in a 1.2× speedup and up to 19% energy reduction.The third contribution, δLTA (δon't Look Twice, It's Alright), decouples camera frame sampling from backend processing. δLTA allows the frontend to identify and skip redundant image regions, focusing processing only on significant changes. δLTA reduces unnecessary memory accesses and redundant computations, lowering localization tail and average latency by 7.2% and 15.2%, respectively, and energy consumption by 17%.Finally, IRIS (Image Region ISP-Software Prioritization) repurposes computations performed by the frontend ISP, segmenting and prioritizing image regions based on detail and motion. IRIS allows the backend to process relevant regions first, reducing latency and energy consumption by up to 9% in tail latency, 20% in average latency, and 16% in energy savings without additional overhead.

DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING

  • MAZZATURA, ISABELLA: An integral methodology for the special inspection of concrete bridges with bonded post-tensioned cables.
    Author: MAZZATURA, ISABELLA
    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: Department of Civil and Environmental Engineering (DECA)
    Mode: Change of supervisor
    Deposit date: 20/06/2024
    Reading date: 26/07/2024
    Reading time: 11:00
    Reading place: AULA VILLAGGIO, SCHOOL OF ENGINEERING, Largo Lazzarino, 1 (Pisa, Itàlia) https://meet.google.com/oez-rwer-cry
    Thesis director: CASAS RIUS, JUAN RAMON | CAPRILI, SILVIA | SALVATORE, WALTER
    Committee:
         PRESIDENT: BARTOLI, GIANNI
         SECRETARI: MORELLI, FRANCESCO
         VOCAL: SILVA CARVALHO CAMPOS E MATOS, JOSE ANTONIO
         VOCAL: STRAUSS, ALFRED
         VOCAL: SAS, GABRIEL
    Thesis abstract: The inspection and the consequent assessment of prestressed concrete bridges with post-tensionedcables is a complex issue. The system was conceived in an era in which there were no doubts about thedurability of the concrete. Moreover, avoiding the cracking of the concrete meant the total protection ofthe high-strength steel cables against corrosion. There was also the additional protection grouting layer.Thus, the first designers did not worry about providing inspection methodologies. When the first suddencollapses occurred, engineers questioned the possible damage mechanisms. Nowadays, a consolidatedinspection method is still missing. The research focuses on two major subjects, i.e. how to perform theinspection and how many tests to carry out for a reliable result. Some Non-Destructive Tests (NDTs)were selected and tested both in the laboratory and in situ. The required characteristics must be theeasiness of application, the low effort in terms of time and money, and their reliability. The lab campaignswere executed mainly to calibrate the procedures and collect data. Ground Penetrating Radar (GPR) wasselected for individuating tendons, while Ultrasonic Tomography (UT) for locating void regions. Even ifthe absence of grout is not sufficient for the corrosion trigger, the hypothesis of correspondence of voidand corrosion is conservative. Seven specimens were realised to state the accuracy of the twotechniques. The GPR was reasonably accurate in locating the tendons. It was possible to obtain a Normaldistribution with a good fit to the data, with parameters mean of 0.702 cm and a standard deviation of1.52 cm, describing the error. The UTs’ reliability was assessed by the Probability of Detection model. Itresulted that, stated 95% confidence and 90% probability of detection, the system can detect voidslonger than 30 cm. The remaining prestress estimation allows to state the losses' entity and indirectlyidentify damage. The X-ray diffraction technique was selected for the stress estimation on the tendons.During the first laboratory campaign, only wires were tested. The laboratory results showed that themethodology is accurate if the residual stresses are known and the load level does not influence theresults. Given that outcome, another campaign was performed, and it showed that the variations inresidual stresses within similar sample groups are not negligible (for wires residual stresses from -30 to-190 MPa, and strands from 120 to 240 MPa). If the residual stresses are considered, a constant relativeerror in the order of 20% is obtained. The saw-cut method was chosen for estimating the stresses onthe concrete. The samples tested in the laboratory were very simple, aiming to assess the accuracy ofthe procedure. The results were not satisfactory; out of twelve tests, only in one case did the testcorrectly estimate the actual stress. The in-situ testing campaign was executed on seven similarstructures to assess the applicability of the NDTs in real conditions. The research deals also with the issueof the number of samples at different levels of evaluation, based on the procedure proposed by theFederal Highway Administration (FHWA), adapted to the Italian Standards, and to different levels ofconfidence for more accurate evaluations. Finally, an overall inspection protocol is thus proposed, tryingto summarize the main outcomes of the research, by the definition of a multi-phase methodology for thespecial inspection in the assessment of PT bridges. The proposal follows the same philosophy as theItalian Guidelines, providing more effort (and tests) for the riskiest structures while tryingto optimise resources. The last part of the thesis concerns the accurate assessment, i.e. how to obtainand use inspection results for bridges requiring accurate evaluation because the special inspection didnot provide a conclusive classification of the actual safety of the bridge.

DOCTORAL DEGREE IN EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS

  • LUCAS ROJAS, LUIS JOSE: Análisis de la direccionalidad en la respuesta de suelo
    Author: LUCAS ROJAS, LUIS JOSE
    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 EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS
    Department: Department of Civil and Environmental Engineering (DECA)
    Mode: Normal
    Deposit date: 10/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: CASELLES MAGALLON, JOSE ORIOL | SALINAS NAVAL, VICTOR
    Committee:
         PRESIDENT: LUZÓN MARTÍNEZ, FRANCISCO
         SECRETARI: MUJICA DELGADO, LUIS EDUARDO
         VOCAL: TAPIA JIMÉNEZ, MARÍA DEL MAR
    Thesis abstract: A problem subjected to multiple researches and currently still is focuses on accurately characterizing the dynamic response ofthe soil when an earthquake occurs. When an earthquake occurs, the seismic signal is modified due to the geological (soilresponse) and topographic conditions of the terrain, phenomena known as site effect. The ground response is mainly showedwhen the seismic signal is amplified at some frequencies due to impedance contrasts under the affected area. Environmentalvibration or microtremors have provided decisive information to become an important source in seismology contributing todetermine the predominant frequency of the soil response, allowing more exhaustive analyzes and greater precision on thegeological and geotechnical conditions of subsoils in densely populated urban areas. The use of microtremor records toestimate the ground response have some advantages, among which highlight the ease of recording and the possibility ofdetermining the predominant frequency of the ground seismic response without earthquake occurrence. The main objective ofthis work is analyzing and evaluating, using techniques and procedures typical of circular statistics, the angular behavior ofenvironmental vibration records, examining whether the direction of the soil response is affected by the presence of suddenlateral geological changes. In the first instance, through descriptive circular statistics procedures, it is quantified and graphicallyrepresented the measures of central tendency and dispersion. Secondly, using techniques and methods typical of inferentialcircular statistics, it is analyzed whether the angular samples extracted from in situ measurements show directional changes inthe soil response caused by the presence of lateral geological variations in the subsoil. Finally, using linear and circularstatistical techniques, it is determined the correlation between two of the circular variables, establishing whether a predictivemodel is viable. In addition, it is defined some pattern of directional behavior of environmental vibration in soils with lateralheterogeneity.

DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING

  • AVILES MURCIA, LUIS ANGEL: Numerical modelling of unsaturated soils with the material point method
    Author: AVILES MURCIA, LUIS ANGEL
    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: Department of Civil and Environmental Engineering (DECA)
    Mode: Normal
    Deposit date: 18/06/2024
    Reading date: 26/09/2024
    Reading time: 15:00
    Reading place: ETSECCPB. UPC, Campus Nord Building C2. Classroom: 212 C/Jordi Girona, 1-3 08034 Barcelona
    Thesis director: PINYOL PUIGMARTI, NURIA MERCE
    Committee:
         PRESIDENT: LIZCANO, ARCESIO
         SECRETARI: OLIVELLA PASTALLE, SEBASTIAN
         VOCAL: CUOMO, SABATINO
    Thesis abstract: The Material Point Method (MPM) is presented as an advanced numerical method used to simulate geotechnical problems subjected to large deformations and soil-structure interaction problems, such as landslides, penetration issues, and collapse of geotechnical structures. Its main advantage is the ability to simulate large movements without the mesh-related problems typical of the standard Finite Element Method (FEM).Simulating different material states and external conditions is a challenging aspect in geotechnical engineering. This process requires a detailed analysis of how to address phenomena such as rainfall and water flow through the soil. Additionally, it is crucial to incorporate material constitutive relationships to properly replicate or predict stress-strain behavior.The modelling of unsaturated soils is necessary in various fields, especially in geotechnical works employing compacted materials such as embankments, dams, fills, and natural slopes. The study and analysis of these soils requires modelling the entire process of the work, from its construction, if applicable, to post-failure behavior.Until now, simulating the unsaturated state of materials has mainly relied on FEM, assuming small deformations at a theoretical level. This involves developing coupled mechanical and hydraulic constitutive models and utilizing advanced numerical tools. This Thesis presents advancements in modelling unsaturated soils in large deformation problems through the development of the MPM. The formulation of a single-point, multi-phases has been used, showing its potential for improving the accuracy and reliability of geotechnical simulations involving large deformations.Firstly, the developments for simulating boundary conditions for unsaturated soils (imposed flow and seepage condition) are presented. These conditions are complex, particularly since the boundary where they are applied is not fixed and must be determined during the calculations. Validation of these conditions is consistently performed using a soil column subjected to infiltration flow. The results are compared with those obtained from a widely used finite element code, giving similar results.Next, for the first time, the modelling of wetting collapse in MPM is proposed. A constitutive model is implemented to capture the key characteristics of unsaturated material behavior. This model is based on critical state theory and employs two alternative formulations, depending on whether Bishop's stress or net stress is used, along with suction. Validation is conducted through conventional laboratory tests.The loss of volume due to wetting is analysed, a characteristic associated with unsaturated soils with an open structure. The loss of suction in the material leads to a loss of strength and, consequently, the possibility of failure. This is illustrated by a physical test conducted in a centrifuge on a slope subjected to a rising water table from the base, which results in the evolution of the saturation front, collapse-induced deformations, and ultimately a landslide when critical saturation conditions are reached.Finally, one of the objectives of this Thesis is to model the entire process of a geotechnical project. To achieve this, a numerical scheme was implemented to simulate construction stages, representing a significant advancement in the application of the MPM for analysing material behavior during the pre-failure stage.Modelling of the construction process is crucial because it not only represents the construction process and the displacements occurring during it, but also establishes the initial state of the structure for subsequent analysis stages. The proposed scheme effectively captures deformations and failure processes during construction, unlike conventional methods based on Eulerian formulations, which cannot accommodate large material displacements during construction
  • ZHOU, YUNFENG: Multiphase fluid flow in heterogeneous / anisotropic deformable geomaterials
    Author: ZHOU, YUNFENG
    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: Department of Civil and Environmental Engineering (DECA)
    Mode: Normal
    Deposit date: 21/06/2024
    Reading date: 26/07/2024
    Reading time: 10:00
    Reading place: ETSECCPB. UPC, Campus Nord Building D2. Classroom: 216 C/Jordi Girona, 1-3 08034 Barcelona
    Thesis director: RODRIGUEZ DONO, ALFONSO | OLIVELLA PASTALLE, SEBASTIAN
    Committee:
         PRESIDENT: CARRERA RAMIREZ, JESUS
         SECRETARI: SAALTINK, MAARTEN WILLEM
         VOCAL: DE SIMONE, SILVIA
    Thesis abstract: Deep geological disposal is currently the preferred option for managing long-lived and heat-emitting radioactive waste. This method involves confining the waste for an extremely long period, potentially severa! hundreds of thousands of years, by placing it in a deep geological formation. Therefore, understanding the migration of gases produced by metal corrosion, microbial degradation, and radiolysis of water within a deep geological repository is crucial for assessing the repository's performance and long-term evolution. The primary objective of this study is to enhance the predictive capability of numerical models for understanding the processes and mechanisms of fracture initiation and growth in claystones with inherent heterogeneity and anisotropy, especially under rapid gas overpressure increases. To achieve this, geostatistics were applied into the finite element method software CODE_BRIGHT to generate a spatially correlated heterogeneous field for porosity. In CODE_BRIGHT, properties such as Young's modulus, intrinsic permeability, and thermal conductivity are functions of porosity, making these properties heterogeneous as well. Additionally, the solution of Eshelby's problem was implemented to introduce both heterogeneity and anisotropy in Young's modulus. lt is crucial to select the appropriate constitutive laws to effectively introduce anisotropy in intrinsic permeability. Simulations were conducted to validate the proposed framework, and sensitivity analyses were performed at both laboratory and in-situ experiment scales to assess the model's performance. The results indicate that the proposed model successfully captures the main observed features of heterogeneous anisotropic claystones during gas injection, including the formation of preferential gas pathways.

DOCTORAL DEGREE IN MECHANICAL, FLUIDS AND AEROSPACE ENGINEERING

  • MORAGA GONZÁLEZ, GRECO ALONSO: Contribution to the structural modal behaviour of reaction hydraulic turbines
    Author: MORAGA GONZÁLEZ, GRECO ALONSO
    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: Article-based thesis
    Deposit date: 11/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: PRESAS BATLLÓ, ALEXANDRE
    Committee:
         PRESIDENT: HOUDE, SEBASTIEN
         SECRETARI: VALENTIN RUIZ, DAVID
         VOCAL: ALVAREZ ALVAREZ, EDUARDO
    Thesis abstract: Current environmental challenges have driven the importance of renewable energies worldwide. Consequently, solar and wind generation plants, in particular, have become increasingly popular and integrated into the electrical grid. Although these plants have increased the worldwide generation capacity, their intermittent nature has generated the need for power regulation mechanisms that allow maintaining a constant energy supply to the grid. In this line, hydroelectric plants have played a crucial role not only in the generation of renewable energies but also in the regulation of the total energy supplied to the electrical grid. Thanks to their quick response and their ability to work in an extended operating range, hydraulic turbines have been used to generate and store available energy (as in the case of pump turbines) based on energy demand.To regulate the energy needed by the grid, units operate under off-design conditions and experience frequent start and stop cycles. With this, machines undergo intense pressure pulsations due to hydraulic instabilities, transient conditions and intense periodic excitations such as rotor-stator interactions. This can lead to potential structural problems and resonances in critical turbine structures, such as the runner, which can result in mechanical failures caused by structural fatigue. To avoid these problems, it is of paramount importance to have an accurate knowledge of the modal behaviour of these structures. Nevertheless, this implies to analyze very complex phenomena such as the influence of heavy and viscous fluids, boundary conditions and structural characteristics on the modal parameters of the structure, and overcoming all of the challenges that can arise during the analysis. In this thesis, the structural modal behavior of reaction hydraulic turbines is studied through the analysis of modal parameters of simple structures and real prototype runners. First, the influence of vibration amplitude and confinement on the damping of a runner in resonance is examined. This study includes an experimental and theoretical analysis of the influence of vibration amplitude on the fluid added damping in a submerged disc vibrating in resonance. The effect of a nearby rigid wall on the correlation between the vibration amplitude and the fluid damping is also analyzed. Analytical explanation and formulation for the complex energy dissipation mechanism are given.Secondly, the mode shapes of bladed runners similar to axial flow machines, including Kaplan turbines, are characterized. This study includes a numerical and experimental analysis of the mode shapes of simple disks and bladed disks. Later, the relationship between the characteristics of the global mode shapes and the number of blades of the structure is examined. Finally, the numerical results of the bladed disks are contrasted with experimental results of a real runner. Both the global and local mode shapes are discussed in this section.Lastly, a real case of a real prototype turbine is analyzed. In this case, strong vibrations and noise were detected in the machine during its commissioning. Through this study, the natural frequencies and mode shapes of the machine are analyzed experimentally and numerically. To determine the origin of the vibrations, a transmissibility analysis is also carried out. Finally, operation tests are conducted to identify the point at which the levels of vibration and noise start to increase. The effectiveness of the proposed measurement strategy, along with the importance of the measurement techniques used, such as the transmissibility test, is demonstrated through a real case. The cause of the problem is found and a solution is proposed and implemented.This thesis is based on three papers published during its development period, in scientific journals indexed in first and second quartiles of the JCR. The details of these articles are explained throughout the thesis and are attached at the end of it.
  • TERRONES FERNÁNDEZ, INÉS: Innovative Modular Pour Plating Microbiology Culture Media Technology
    Author: TERRONES FERNÁNDEZ, INÉS
    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: 27/06/2024
    Reading date: 10/09/2024
    Reading time: 11:00
    Reading place: Defensa pública a la Sala de Juntes de l'Escola Superior d'Enginyeries Industrial, Aeroespacial i Audiovisual de Terrassa (ESEIAAT) de la Universitat Politècnica de Catalunya.
    Thesis director: GAMEZ MONTERO, PEDRO JAVIER | CASTILLA LOPEZ, ROBERTO
    Committee:
         PRESIDENT: GRILLO DOLSET, MARIA JESUS
         SECRETARI: ESCALER PUIGORIOL, FRANCESC XAVIER
         VOCAL: VERNET PEÑA, ANTON
    Thesis abstract: The current methods used in microbiological quality analysis rely on the use of traditional and manual methods, such as the pour plate method. The need to perform more analyses of different matrices makes it necessary to improve these methods. Thus, this thesis focuses on the design of systems in which the manual work of laboratory technicians is reduced. In order to meet the main objective, this thesis has been separated into two subjects, i.e., microbiology and mechanical and fluid engineering. The union of these two fields is essential for the achievement of this need.The starting point for microbiology focused on the separation of culture media into their different phases. This separation would allow both easier maintenance of the media and a simpler dosage of the same. In addition, studies and the establishment of a protocol for sterilizing the culture medium in a microwave oven were also carried out.By means of Computational Fluid dynamics (CFD), studies were carried out to design a static homogenizer so that the culture medium would be completely mixed when pouring onto the plates. In addition, a device was designed with which the dosing of the culture medium, once separated into its components, was possible. The favorable results obtained in both microbiological and engineering studies demonstrate that a pour plate method automation system is possible. Hence, the development of this new line of research will continue, as this study is only the starting point for the development of such a system.

DOCTORAL DEGREE IN NATURAL RESOURCES AND THE ENVIRONMENT

  • CUBIDES PAEZ, DAVID FERNANDO: Biological technologies for nitric oxide abatement
    Author: CUBIDES PAEZ, DAVID FERNANDO
    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 NATURAL RESOURCES AND THE ENVIRONMENT
    Department: Department of Mining, Industrial and ICT Engineering (EMIT)
    Mode: Normal
    Deposit date: 01/07/2024
    Reading date: 26/07/2024
    Reading time: 11:00
    Reading place: Defensa pública a la Sala d'Actes EPSEM (Av.Bases de Manresa, 61-73, 08242 Manresa)
    Thesis director: JUBANY GUELL, IRENE | GAMISANS NOGUERA, XAVIER
    Committee:
         PRESIDENT: RAMÍREZ MUÑOZ, MARTÍN
         SECRETARI: DORADO CASTAÑO, ANTONIO DAVID
         VOCAL NO PRESENCIAL: MARTIN SANCHEZ, MARIA JOSE
    Thesis abstract: Tackling the widespread challenge of air pollution, particularly the reduction of nitrogen oxides (NOx), is critical to improving public health and environmental quality in Europe. Annually, air quality-related problems contribute to some premature deaths across Europe, underlining the urgent need for effective pollution control strategies. This PhD thesis explores innovative biotechnological processes for NOx removal, focusing on the potential of biological treatments as sustainable and cost-effective alternatives to conventional methods.Conducted at the Department of Mining, Industrial Engineering and ICT of the Universitat Politècnica de Catalunya (UPC) and the Eurecat Water, Air and Soil Technology Unit, this research is part of a collaborative effort to bridge the gap between academic studies and industrial applications. The thesis investigates the effectiveness of ionic liquids (ILs) and non-aqueous phase liquids (NAPs) as mass transfer vectors to enhance nitrogen oxide (NO) solubility and in turn improve NO bioavailability for microbial degradation. These vectors have the potential to revolutionize the design and operation of biological treatment systems of low water-soluble gases by improving their efficiency and scalability.The thesis systematically reviews existing NO control technologies to lay the groundwork for the introduction of bio-based alternatives. It delves into the selection and optimization of materials and methods, with emphasis on experimental designs that facilitate robust and reliable results. By improving mass transfer from the gas to the liquid phase, the research aims to address one of the main limitations faced by current biological treatments when treating hydrophobic gases such as NO.This research was supported by several academic and government grants, reflecting its importance and potential impact. The results are expected to open a door to the study of a new industrial technology, providing a solid scientific basis for further research into new alternatives for gas treatment.

DOCTORAL DEGREE IN NUCLEAR AND IONISING RADIATION ENGINEERING

  • GARCIA BALCAZA, VICTOR: PyMCGPU-IR, a computational Monte Carlo application for occupational dosimetry in interventional radiology procedures
    Author: GARCIA BALCAZA, VICTOR
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN NUCLEAR AND IONISING RADIATION ENGINEERING
    Department: Institute of Energy Technologies (INTE)
    Mode: Normal
    Deposit date: 10/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: DUCH GUILLEN, MARIA AMOR | GINJAUME EGIDO, MERCE
    Committee:
         PRESIDENT: VERDÚ MARTÍN, GUMERSINDO
         SECRETARI: SEMPAU ROMA, JOSEP
         VOCAL: CARRASCO DE FEZ, PABLO
    Thesis abstract: Interventional radiology procedures expose both patients and operators to radiation. It is crucial to minimise this exposure and comply with dose limits while ensuring the success of the procedure. Personal protective equipment and dosimetry are essential components in achieving these objectives. However, occupational dosimetry presents challenges due to inhomogeneous radiation fields, which imply that operators should wear multiple dosemeters, although typically a single dosemeter is used in a single location to measure personal dose equivalent. Computational methods offer an alternative for occupational dosimetry, allowing for dose calculation at multiple points. In particular, Monte Carlo codes have long been used for simulating the transport of radiation particles.This thesis focuses on the development and validation of PyMCGPU-IR, an application designed to estimate occupational doses in interventional radiology procedures, operating automatically without user intervention and doing so within short time frames. PyMCGPU-IR is based on the Monte Carlo code MCGPU-IR, which leverages the computational power of GPUs to simulate particle trajectories simultaneously. MCGPU-IR can calculate deposited dose values in voxelized geometries of patients and operators in less than two minutes per event. PyMCGPU-IR extracts procedural information from the RDSR file and the main operator’s position from a tracking camera system, automating the execution of the MCGPU-IR code and providing the desired dose values.The first step of this thesis was the validation of the MCGPU-IR code, comparing its occupational dose results with those of the standard Monte Carlo code PENELOPE. Subsequently, its results were compared with occupational dose values measured with dosemeters, revealing a good agreement. However, scenarios involving shielding showed a tendency of MCGPU-IR to underestimate the occupational dose.PyMCGPU-IR has been evaluated in real clinical scenarios, using phantoms that simulate the bodies of patients and operators, with satisfactory results. However, in real medical interventions, certain information required for PyMCGPU-IR, such as the patient table position, the presence of shielding, or the operator's position, was often unavailable and had to be manually entered into the application based on assumptions. As a result, PyMCGPU-IR still has limitations in fully automating the process in real medical interventions. Nevertheless, once these assumptions are considered, PyMCGPU-IR can calculate personal dose equivalent Hp(10) values in operators with differences compared to experimental measurements, within the accepted tolerance in occupational dosimetry.In addition to calculating Hp(10), PyMCGPU-IR can also calculate organ dose values, effective dose for operators, and skin dose values for patients in less than two minutes per irradiation event. Furthermore, it provides deposited dose values in voxels, facilitating graphical visualisation of dose distribution.

DOCTORAL DEGREE IN OPTICAL ENGINEERING

  • ROVIRA GAY, CRISTINA: Objective Evaluation on the Effectiveness of Vergence Vision Training Based on the Analysis of Eye Movements
    Author: ROVIRA GAY, CRISTINA
    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: 01/07/2024
    Reading date: 05/09/2024
    Reading time: 11:30
    Reading place: Auditori Joan Salvadó del Centre Universitari de la Visió
    Thesis director: MESTRE FERRER, CLARA | ARGILÉS SANS, MARC
    Committee:
         PRESIDENT: PIÑERO LLORENS, DAVID PABLO
         SECRETARI: VILASECA RICART, MERITXELL
         VOCAL: JOLLY, JASLEEN K
    Thesis abstract: When an object of interest is detected in the visual field, a saccadic movement is made and the attention and gaze are centred on it. During this visual fixation, optokinetic eye movement occurs to maintain the retinal image position stable and, at the same time, small fixational eye movements take place. Vestibular eye movements also take part in this action to guarantee the accurate stabilization of the eyes during rotations and translations of the head. If the object of interest moves in the frontal plane, smooth pursuit eye movements allow the eyes to follow the object as it is moving. If the object moves in depth, vergence eye movements align the two eyes with the target at different distances. Specifically, the vergence system, which controls binocular alignment, aligns both foveae with the object of interest allowing fusion of the retinal images into a single percept. Vergence eye movements will be described in a greater detail in this Thesis as they are the most relevant types of eye movements for the purpose of this Thesis.Phoropter rotary prisms and prism bars are commonly used to evaluate the amplitude of both the positive (convergence) and the negative (divergence) fusional vergence amplitudes, measuring the blur, break, and recovery of single vision points. The blur point informs about the amount of relative fusional vergence that can be stimulated without the intervention of accommodation. The break point assesses the total amplitude of fusional vergence amplitudes, and the recovery point indicates the patient’s ability to recover single binocular vision after diplopia occurs. These two tests are subjective and depend on the answers of the patients, optometrist’s experience, manual dexterity, and examination criteria, which leads to variability of the results and poor repeatability. One of the purposes of this PhD Thesis is to evaluate objectively the fusional vergence amplitudes and compare the results with the conventional subjective clinical tests. Vision therapy or vision training, also called, orthoptics has been demonstrated to be an effective treatment for convergence (CI), among other binocular dysfunctions. The objective of this treatment is to increase the amplitude, speed, accuracy of accommodative and vergence responses, and the visual comfort. Since 1855, vision therapy has been the primary treatment for CI and there are validated protocols to improve the abilities of the binocular vision system. The objective monitoring of the effectiveness of this treatment for normal binocular vision participants is a novelty of this PhD Thesis. In this PhD Thesis, vergence responses are evaluatep in a subjective and an objective way using conventional procedures and the eye tracker EyeLink 1000 Plus (SR Research Ltd., Ontario, Canada). The main purpose of this PhD Thesis is to assess objectively the effectiveness of a conventional vision therapy protocol for training vergence responses

DOCTORAL DEGREE IN PHOTONICS

  • BALANZÓ JUANDÓ, MARIA: Certification in quantum information theory: key distribution, self-testing and entanglement
    Author: BALANZÓ JUANDÓ, 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 PHOTONICS
    Department: Institute of Photonic Sciences (ICFO)
    Mode: Normal
    Deposit date: 10/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: ACÍN DAL MASCHIO, ANTONIO | FARKAS, MÁTÉ
    Committee:
         PRESIDENT: TURA I BRUGUÉS, JORDI
         SECRETARI: ARGÜELLO LUENGO, JAVIER
         VOCAL: MANCINSKA, LAURA
    Thesis abstract: In the beginning of the last century, we witnessed a change of paradigm in how physics described the world with the formulation of quantum mechanics. This new theory shook the pillars of science by setting fundamental limits on our ability to describe nature. It was able to explain the laws that govern physics at the microscopic level, which could not be explained by means of the existing laws. The behavior at such small scales differs significantly from our daily experience. For instance, exotic phenomena such as entanglement or nonlocality are exclusively observed at the microscale. Entanglement and nonlocal correlations represent two essential resources in quantum information processing, enabling novel tasks that are unattainable within a classical framework.The end of the twentieth century has seen a wave of studies on the fundamental properties of quantum theory. Nowadays, as a consequence of these advances in quantum theory and experiments, various companies are selling devices claimed to perform a quantum information task with no classical analog, such as quantum random number generators, prototypes of quantum computers, or quantum key distribution devices. Since quantum devices cannot be simulated classically, it is hard to verify them using only classical resources, which are the ones available to the average user. Hence, a natural question to ask ourselves is how we can verify the properties and functioning of quantum devices in an efficient way.In this context, device-independent protocols have been developed in quantum information theory over the past decade. The main advantage of such protocols is that users do not have to make any assumption about the inner workings of their devices, considering them as black boxes. The security and success of a device-independent protocol relies on the observation of nonlocal correlations in a Bell experiment. This thesis is dedicated to provide tools to achieve the certification of quantum information devices or tasks in a device-independent way.In the first part of this thesis, we focus on certifying the security of device-independent quantum key distribution. To this end, we first study whether Bell nonlocality is a sufficient condition for security in the most used protocols, proving that there exist nonlocal correlations that are not useful for secure device-independent quantum key distribution using these protocols. Moreover, we study noisy scenarios, that is when experimental imperfections are present, and derive upper bounds on the two-way and one-way key rates for this kind of protocols.In the second part, we study self-testing, which is one of the simplest device-independent protocols. Its goal is to recover quantum states solely from the observed measurement correlations. In the majority of quantum information processing tasks one needs to consider a particular quantum state, making the certification of quantum states of great importance in the device-independent paradigm. We prove that all multipartite states of qubits can be self-tested. Moreover, we study self-testing in higher-dimensional systems.Finally, in the third part of this thesis, we tackle the problem of certification of entanglement. It is well known that certifying the presence of entanglement in a system is a hard task. The key methods for entanglement detection, entanglement witnesses and positive maps, rely on our understanding of the mathematical features of multilinear algebra. By using the fact that any separable state is one to one related to a matrix inequality, we port previously known results on the entanglement of states with positive partial transpose into the domain of matrix inequalities, which also allow us to translate multilinear positive maps back into entanglement witnesses. This approach leads to a unified treatment of a large class of matrix inequalities, allowing us to find new inequalities on the basis of advances in entanglement theory.
  • CIRAUQUI GARCÍA, DAVID: Optimization with spin glass models
    Author: CIRAUQUI GARCÍA, DAVID
    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: 20/06/2024
    Reading date: 27/09/2024
    Reading time: 10:30
    Reading place: ICFO, Mediterranean Technology Park, Avinguda Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona
    Thesis director: LEWENSTEIN, MACIEJ | MARTÍNEZ SAAVEDRA, JOSÉ RAMÓN | RYSZARD GRZYBOWSKI, PRZEMYSLAW
    Committee:
         PRESIDENT: MAZZANTI CASTRILLEJO, FERNANDO PABLO
         SECRETARI: PRUNERI, VALERIO
         VOCAL: DELLANTONIO, LUCA
    Thesis abstract: With applicability on almost every aspect of our lives, optimization problems are ubiquitous to a broad range of fields within both scientific research and industrial environments. As such, these are growing in size and complexity at a fast pace, and are only expected to continue to do so. Accordingly, the urgency for better methods that can yield more optimal solutions in shorter times is increasing and, while the development of quantum computing technologies that are capable of tackling these problems evolves steadily, it does so too slowly for the challenges that nowadays society's demands represent. Consequently, a lot of effort is being invested to further develop classical methods and machines that are specially designed to solve optimization problems of relevant enough sizes. The present thesis is framed within this paradigm: classical optimization techniques are studied from various different perspectives, with the goal of improving their efficiency. To this end, we first dive into basic concerns related to the physical properties of the systems that allow for the convenient formulation of industrially-relevant optimization problems, namely spin glasses with quenched disorders. The understanding of such properties is of utmost importance for the correct designing of the annealing schedules used by thermally-based optimization methods. We then study the impact that the hidden correlations of the pseudo random number streams used in their simulations have in the results by comparing simulations using PRNGs of various qualities and perfectly random QRNGs. To conclude, we investigate novel ways, inspired by quantum-mechanical systems, to efficiently navigate the energy landscapes of spin glasses in classical algorithms, which has the potential of preventing the simulations getting stuck into local energy minima and thus reaching more optimal solutions.
  • LUQUE MERINO, RAFAEL: Optoelectronic studies of strongly correlated 2D materials
    Author: LUQUE MERINO, RAFAEL
    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: 13/06/2024
    Reading date: 02/09/2024
    Reading time: 11:00
    Reading place: ICFO, Mediterranean Technology Park, Avinguda Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona
    Thesis director: EFETOV, DMITRI K.
    Committee:
         PRESIDENT: POCCIA, NICOLA
         SECRETARI: KOPPENS, FRANK
         VOCAL: TÖRMÄ, PÄIVI
    Thesis abstract: The study of strongly-correlated matter in two-dimensional materials has emerged as a exciting prospect for the exploration of condensed matter physics, as well as the design of novel device platforms. Moiré engineering , where the 20 layers feature an interlayer twist angle, has proven to be a powerful tool to engineer electronic correlations . In magic angle twisted bilayer graphene, a twist angle of 1.1° between the graphene layers generates a moiré superlattice potential. A flat electronic band appears at the Fermi level, in which a variety of interaction-driven , many-body quantum phases can emerge . Another avenue to study strong electronic correlations in two dimensions is the exfoliation of intrinsically correlated bulk crystals into the atomic limit.The optoelectronic study of strongly-correlated systems in 20 heterostructures stands out as a powerful probe, as it can provide insight into both the electronic transport properties and the fundamental light-matter interaction in these systems . In this thesis , we study two strongly correlated 20 materials: MATBG and the cuprate superconductor Bi2Sr2CaCu208-delta (BSCC0-2212). We leverage different optoelectronic techniques to study the fundamental properties of the correlated electrons in the MATBG flat bands and the potential of two-dimensional BSCC0-2212 layers for applications in quantum sensing .First, we investigate the electronic spectrum of the MATBG flat bands through the study of their thermoelectric transport . We use an optical excitation to induce a thermal gradient, which in turn generales a charge curren!. We report anomalous thermoelectricity which provides strong evidence for the coexistence of localized and de-localized electronic states in the strongly-interacting flat bands.Next, we study the dynamics of hot carrier cooling in the MATBG flat bands using a frequency-resolved photomixing technique . Strikingly, we find that hot carriers can efficiently relax their energy down to cryogenic temperatures ; in contras! to the case of bilayer graphene samples . We propose a novel Umklapp electron-phonon scattering mechanism for hot carriers in MATBG, enabled by the moiré superlattice potential.Lastly, we explore the development of superconducting photodetectors with high-T_c based on ultrathin BSCC0-2212 flakes . We fabricate high quality samples that exhibit remarkable performance at telecom wavelengths . We observe fast and sensitive bolometric response at T = 77 K in free-space and waveguide-coupled devices , as well as single-photon sensitivity at T = 20 K through a non-bolometric , avalanche detection mechanism .
  • SOUNDARAPANDIAN, KARUPPASAMY: Graphene based photodetectors for on-chip and free-space data communication applications
    Author: SOUNDARAPANDIAN, KARUPPASAMY
    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: 10/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: KOPPENS, FRANK
    Committee:
         PRESIDENT: BOGGILD, PETER
         SECRETARI: PRUNERI, VALERIO
         VOCAL: COLETTI, CAMILLA
    Thesis abstract: Moore's law, a longstanding guide for the semiconductor industry, successfully predicted the exponential growth in computing power by doubling transistor counts every two years. However, recent challenges in maintaining this pace, attributed to physical limitations, energy consumption, and escalating costs, have prompted a shift in focus towards two-dimensional (2D) materials in semiconductor technology. This thesis aims to bridge the gap in understanding the complexities of incorporating 2D materials, such as Graphene (Gr), Transition Metal Dichalcogenides (TMD), and hexagonal boron nitride (hBN), into Complementary Metal-Oxide-Semiconductor CMOS platforms, paving the way for innovative optoelectronic devices with improved functionality to overcome these challenges. High-quality heterostructuresThis thesis investigates the crucial role of encapsulants and substrates in Gr-based heterostructures, highlighting their impact on electronic transport characteristics, such as hysteresis (∆n), carrier mobility (µ), and residual charge carrier concentration (n*). Owing to the quality and integration complexity of scalable large-area thick hBN, this thesis explores the utilization of TMD-like tungsten diselenide (WSe2) and tungsten disulfide (WS2) as substrates and encapsulants, respectively, for Gr. The hybrid heterostructures fabricated with WSe2/Gr/hBN and WS2/Gr/hBN exhibited a high µ of ~170,000 and ~140,000 cm2V-1s-1 with a n^*of ~7 and 8 x 1010 cm-2 respectively. This study underscores the significance of substrate engineering, particularly for WS2. A successful demonstration of the effectiveness of TFSI-treated WS2 in encapsulating Gr and its role as a gate dielectric has been established. The treated devices exhibited remarkable stability and resilience, leading to a low ∆n of ~2 x 109 cm-2 with a µ of ~62,000 cm2V-1s-1 and a n^* of ~1.7 x 1011 cm-2. Waveguide-integrated photodetectorsThe exponential growth of internet users and data traffic necessitates higher bandwidth capabilities in communication systems. Optical transceivers play a pivotal role in meeting this demand, particularly in data centers and broadband access networks. This thesis focuses on the crucial components of optical transceivers, specifically photodetectors (PD), optimized for a wavelength of 1550 nm, a standard for long-distance communication in optical fibers. This thesis explores a photothermoelectric (PTE) WSe2 encapsulated Gr photodetector on a waveguide to address this challenge. Up on a comprehensive analysis of the device's design, the fabricated PD with different widths exhibited a responsivity up to ~12 V/W (long) or 0.1 A/W and ~32 mA/W or 18 V/W (short) with a setup limited bandwidth of 110 GHz. PDs also demonstrated direct detection of NRZ and PAM-4 optical signals up to 120 and 160 Gbps, respectively.Wireless receiversMeanwhile, in wireless telecommunications, efforts must be directed towards boosting data rates to accommodate growing data traffic, as indicated by Edholm's law. The proposed 6G wireless devices are expected to achieve peak data rates of up to 1Tbps. To overcome speed bottlenecks, this thesis proposes exploring the terahertz (THz) range, with a focus on the sub-THz (~200GHz-300GHz) window, exhibiting low-attenuation demands for short-range (<200m) wireless applications. We performed an extensive investigation and optimization of the performance of a PTE-based Gr photodetector using various encapsulants. Among these, the hBN-encapsulated Gr PDs exhibited superior performance compared to their counterparts (PD with CVD Gr), with an elevated responsivity of ~240 (~30) V/W and low noise equivalent power (NEP) of ~1 (~9) x 10-11 W/√Hz. The fabricated PDs exhibited a bandwidth of approximately 1.9 GHz, enabling data rates of 2 Gbps. Finally, we developed a Gr-based receiver, establishing a sub-terahertz wireless communication link that achieved data rates of up to 3 Gbps and efficiently operated over a distance of 2.5 meters.

DOCTORAL DEGREE IN POLYMERS AND BIOPOLYMERS

  • LOZANO HERNÁNDEZ, NEKANE: Microtexturization of liquid silicone rubber surfaces by injection moulding
    Author: LOZANO HERNÁNDEZ, NEKANE
    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: 29/05/2024
    Reading date: 03/09/2024
    Reading time: 11:00
    Reading place: Sala Polivalent de l'Edifici I, Edifici I, planta baixa, Campus Diagonal-Besòs
    Thesis director: PUIGGALI BELLALTA, JORGE | DEL VALLE MENDOZA, LUIS JAVIER
    Committee:
         PRESIDENT: RODRÍGUEZ FERNÁNDEZ, ISABEL
         SECRETARI: CASELLAS PADRO, DANIEL
         VOCAL: TYLKOWSKI, BARTOSZ
    Thesis abstract: Nature is in continuous change and evolution in response to environmental shifts. That is because different micro- and nanotextures have emerged on some plant leaves or insect skins. These surface patterns enable them to possess advanced surface properties. Some examples include the superhydrophobic and self-cleaning leaves of the lotus plant, or the dry adhesion found on gecko feet. There has been a strong trend in recent years to transfer these surface textures to industrial applications to replace various coatings currently in use. The development of transformation technologies and the extensive knowledge of materials developed in recent decades have allowed for the extension of materials onto which these microtextures can be replicated.In the case of Liquid Silicone Rubber (LSR), studies on replication focus on laboratory-scale technologies that allow for high replication but low production throughput. However, these materials possess properties of great interest and can have many synergies with microtexturing: good biocompatibility for use in medical devices, weather resistance for self-cleaning or superhydrophobic surfaces, or good mechanical and chemical resistance that can extend the lifespan of microtextures on the surface. In order to extend studies on replication techniques of microtextures on liquid silicone surfaces, this thesis has been developed focusing on replication through injection of microtexturized inserts. There have been some previous works on replication using this technology; however, they fail to achieve good demolding or uniform textures in height due to the use of textured metallic inserts. Therefore, this thesis proposes the use of textured films to facilitate demolding due to the flexibility of the film.This thesis is divided into two main parts: The first part consists of the development of tools and technology for the replication of liquid silicone parts by injection. Firstly, optimization is carried out on the manufacture of textured films by nanoimprint lithography to withstand the injection conditions of this material. After this initial optimization and with the manufacturing of the necessary tools, a study and optimization of different part geometries for the different studied microtextures (pillars, lines, and holes ranging from 1 to 50 microns) are conducted. The second part of the thesis consists of an extensive study of different advanced surface properties due to microtexturing. This includes properties such as surface wettability or roughness studies, as well as different studies of part durability for the application of different mechanical stresses. Additionally, emphasis is placed on the study of biological properties, of interest in the medical sector. The studies focus on the variation of cellular growth and adhesion due to the presence of microtextures. Based on all the results obtained, a use case of an optogenetic implant is proposed.From the results obtained, it can be concluded that the replication method proposed and developed in this thesis is an optimal method for industrial scaling of these microtextures in liquid silicone. Not only because of its high production throughput but also because of the versatility of part geometries and microtextures it allows. This versatility of microtextures enables the acquisition of a wide range of surface properties of high interest at an industrial level. Particularly in the case of the medical sector, where a use case of a microtexturized implantable device with this technology has been demonstrated, which could be extendable to other applications.

DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS

  • MOLINA ORDÓÑEZ, CARLOS: Ionospheric Scintillation in GNSS Signals: a Tool for Earth Observation
    Author: MOLINA ORDÓÑEZ, 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: 05/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: CAMPS CARMONA, ADRIANO JOSE | PARK, HYUK
    Committee:
         PRESIDENT: WICKERT, JENS
         SECRETARI: SANZ SUBIRANA, JAIME
         VOCAL: GARCÍA RIGO, ALBERTO
    Thesis abstract: This PhD thesis is intended to study ionospheric scintillation and its relationship with some of its sources, in particular the observed correlation between the ionospheric perturbation and the lithosphere. However, before addressing this topic, some simulators and models have been developed.A trans-ionospheric ray tracer has been developed in this thesis in order to simulate the effects of an electromagnetic wave traveling through the Earth's ionosphere. It consists of an updated version of an old algorithm that has been provided with the most recent models of the ionospheric density, geomagnetic field, and atmospheric composition, in addition to a model for equatorial plasma bubbles.Ionospheric scintillation is the term used to describe a phenomenon affecting electromagnetic waves traveling through the ionosphere which suffer from rapid changes in its intensity and phase. It is motivated by the turbulent electron density fluctuations within the ionosphere in different temporal and spatial scales.Ionospheric scintillation is more probable to occur in equatorial regions after the sunset, and in polar regions, but it is highly related to external perturbations from the space weather. Its complex behavior is studied by mathematical models such us the Rino's model, which uses a phase screen to derive the phase and intensity changes of the waves crossing it. This model is capable of estimating the scintillation indices ($S_4$, and $\sigma_\phi$) for any ray geometry, but it needs some inputs characterizing the ionospheric conditions. These inputs refer to the intensity and spectral distribution of the fluctuations ($C_kL$, and $q$), and its shape and velocity.The WBMOD model is one of the climatological models widely utilized to provide the ionospheric scintillation parameters globally as a function of the date, time, location, and geomagnetic/solar conditions. However, this model is not freely available. The work presented in this PhD thesis is the development of an approximated twin model of WBMOD based on neural networks trained with available WBMOD data.Ionospheric scintillation can be estimated from GNSS signals, through different techniques. First, by direct measurement of the GNSS signal in ground stations. Second, by using the GNSS Reflectometry technique, which senses from LEO satellites the wave reflected over the ocean. Third, by employing the GNSS radio occultation technique, which studies the signal coming from GNSS satellites near the horizon, crossing the ionosphere tangentially. These three techniques together allow a wider coverage of the Earth, particularly, over regions where the traditional ground stations do not exist, i.e. oceans.Many studies in the last decades have evidenced a coupling between the lithosphere, the atmosphere, and the ionosphere, the so-called LAIC. These studies report changes in the ionosphere total electron content, perturbation in the magnetic field, or detection of extremely low frequency radiation, among other phenomena, both before and after seismic events. In this thesis, the relationship between the ionospheric scintillation detected by the three methods mentioned before, and seismic events has been studied, focusing on the precursory signatures. For this, a preliminary study to assess the effectiveness of the GNSS Reflectometry to detect ionospheric scintillation has been performed using CYGNSS GNSS-R data.Finally, this PhD thesis presents the statistical study on the relationship between ionospheric scintillation anomalies and earthquakes globally, and in a second step, related to the localized seismic activity produced by a volcanic eruption in La Palma in 2021. The results of these parts found a small signature of the ionospheric scintillation anomalies as earthquake's precursory signals. However, this evidence is so small that it does not allow its straightforward use as an early alarm system for seismic activity.

DOCTORAL DEGREE IN SUSTAINABILITY

  • HEREU MORALES, JOAN: A narrow contribution to quantification for a sustainable society: from interdisciplinary review and policy analysis to a new method for the assessment of climate neutrality
    Author: HEREU MORALES, JOAN
    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: 11/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: VALDERRAMA ANGEL, CESAR ALBERTO
    Committee:
         PRESIDENT: DILLMAN, KEVIN
         SECRETARI: DE PABLO RIBAS, JOAN
         VOCAL: MAYOR PILLADO, ÁLVARO
    Thesis abstract: Humanity faces in the XXI Century the challenge of transformation towards a sustainable society. The ecological crisis, in which climate change plays an important role, threatens to alter the natural cycles of the planet up to a point of no return, seriously compromising both natural ecosystems and human life on the planet. Such natural degradation finds its origins in the industrial revolution, and has been fed by human activities ever since then. Over the last decades, efforts to mitigate the crisis have taken a part on the public ruling of human society at a global scale, but these have so far failed to offer real perspectives of improvement.This doctoral thesis acknowledges this situation and navigates some of the different paths through which sustainability science can contribute to mitigate the crisis. The final goal of the thesis is contributing in the development of quantified parameters of sustainability that enhance effective decision making at a public level. Due to the heterogeneity, interdisciplinarity and broadness of the field of sustainability science, the final goal of the thesis requires a previous process of defining the contextual and conceptual frameworks through literature review on various topics as well as a focus on what, where and how to quantify prior to developing the quantification method. The former involves conceptual clarification on sustainability and a sustainable society, as well as a literature review and analysis on the state of art of current public plans for sustainability at an intergovernmental level, given the global impact of the crisis. Additionally, it involves an approach to economic discussions on growth and to the field of philosophical reflections concerning the historical role of human society. The latter is defined as follows: the what is set on the climate impact of production activities, the where is set on the agricultural sector and the how is set on enhancing holisticness and comprehension of results. The consecutive process to this one is the definition and application of the new sustainability quantification method.Results of the thesis include a conceptual model of a sustainable society, an analysis on the environmental sustainability of the transformational plans within the European Green Deal, the development of a new method for quantifying the climate impact of production systems and assessing their path towards climate neutrality, as well as the application of such method on the GHG emissions from production, transport and agricultural use of N-fertilizers in Spain during the period 1960-2100. Due to the findings on the literature review, as well as throughout the different studies of this doctorate, such results are discussed with the focus set on the influence of the global economic model and precisely of economic growth on the consecution of a sustainable society.Main conclusions of this work highlight that the ecological crisis has deeper roots on human society than currently addressed by its transformational plans. In order to achieve a sustainable society, including climate neutrality, it is necessary to transform the economic model and abandon the industrial-societal axioms including a review of endless economic growth, irrational techno-optimism and dissatisfying materialism. Post-growth economics are encouraged to be further explored as they might offer the key towards human wellbeing in balance with a finite planet.

DOCTORAL DEGREE IN TEXTILE AND PAPER ENGINEERING

  • FERNÁNDEZ SANTOS, JULIA: DESARROLLO DE NUEVAS ESTRUCTURAS LAMINARES DE NANOCELULOSA CON PROPIEDADES AVANZADAS PARA EL PACKAGING
    Author: FERNÁNDEZ SANTOS, JULIA
    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 TEXTILE AND PAPER ENGINEERING
    Department: Department of Engineering Graphics and Design (DEGD)
    Mode: Normal
    Deposit date: 03/07/2024
    Reading date: 31/10/2024
    Reading time: 11:00
    Reading place: Defensa pública a la Sala de juntes del TR5, ESEIAAT (TERRASSA).
    Thesis director: RONCERO VIVERO, MARIA BLANCA | VALLS VIDAL, CRISTINA
    Committee:
         PRESIDENT: CAMINAL SAPERAS, GLÒRIA
         SECRETARI: VIDAL LLUCIA, TERESA
         VOCAL: GRIFOLL RUIZ, MAGDALENA
    Thesis abstract: Changes in the use of raw materials and major lifestyle changes in first world societies have driven the massive use of petroleum-based materials in a wide range of applications. Plastic waste has become pervasive in our surroundings, creating serious problems concerning both the environment (affecting biodiversity) and human health. For this reason, it is essential to develop alternatives to these materials, which are finite, polluting and non-biodegradable. It is upon this context that the present doctoral thesis is framed, wherein from one of the most abundant natural biopolymers on the planet (cellulose), new laminar and transparent biomaterials with barrier and biodegradable properties were created, suitable for use in food packaging. Specifically, nanocellulose was used, combined with natural additives or, chemically or enzymatically functionalised to obtain the required properties: transparency, physico-mechanical properties, acting as a barrier to water and water vapour, grease and oxygen. In order to achieve the objective of this thesis, three work lines have been followed.In the first line of work, films were prepared using crystalline nanocellulose (CNC) and the effects of different natural additives such as sorbitol, glycerol, maltitol, xylitol, mannitol, gellan gum, and ethylene glycol on the CNC matrix at different doses were evaluated. Transparent films with UV protective properties were obtained. Most of the additives showed good results at low doses, both in terms of elongation and tensile strength, as well as to homogeneity, smoothness, and oxygen and water barrier properties (including at high relative humidity conditions). At all the doses tested, biodegradability of films was improved. With the two additives that provided the best properties (maltitol and xylitol), the possibility of a synergistic effect between them was evaluated an improvement in transparency, tensile strength, elongation, as well as an improvement in water vapour and oxygen barrier properties were observed. The second line of work was also based on CNC, but this time it was mixed with fibrillar nanocellulose (CNF) and/or carboxymethylcellulose (CMC) in varying percentages. The obtained films also demonstrated good barrier and mechanical properties. Both the CNF and the CMC increased tensile strength and elasticity (elongation) in the CNC films, as well as providing increased resistance to airflow and UV light. Moreover, both increased hydrophobic, and barrier properties to water vapour as well as oxygen. These effects were confirmed by a food packaging simulation test, in which the CMC films provided the best food preservation. Finally, it was demonstrated that the created films were biodegradable, and this property was enhanced in the presence of either CMC or CNF.Finally, the final line of work began with CNF films and investigated the effects of selective oxidation with sodium periodate upon the creation of aldehyde groups. These groups formed hemiacetal and hemialdal bonds and consequently the resulting films were highly transparent, elastic, and resistant, even under conditions of humidity saturation. In fact, the oxidation treatment with periodate reduced the polarity of the films, thereby significantly improving their water barrier properties. The presence of aldehyde groups allowed the immobilisation of the enzyme laccase, which efficiently captures oxygen and therefore prevents food decomposition. The laccase-containing films oxidised 80% of the methylene blue dye and maintained their enzymatic activity after a month of storage and twelve cycles of reuse, which opens the door to the possible creation of a reusable packaging that could substitute single-use packaging.

DOCTORAL DEGREE IN URBANISM

  • MEDINA ESTRADA, ISAURA: Tijuana, un puzle de fragmentos urbanos. Origen y evolución de una ciudad fronteriza
    Author: MEDINA ESTRADA, ISAURA
    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: Department of Urbanism, Territory and Landscape (DUTP)
    Mode: Normal
    Deposit date: 15/05/2024
    Reading date: 05/09/2024
    Reading time: 15:30
    Reading place: Room CB4 ETSAB. Main floor - Public link for the videoconference: meet.google.com/ggv-noef-nic
    Thesis director: SABATE BEL, JOAQUIN | PEREMIQUEL LLUCH, FRANCISCO
    Committee:
         PRESIDENT: CASTIÑEIRA PALOU, MARIA ISABEL
         SECRETARI: PAGLIUSO DE ANDRADE, ANA CAROLINA
         VOCAL NO PRESENCIAL: IRACHETA CENECORTA, ALFONSO XAVIER
    Thesis abstract: The present research is an urban study about Tijuana, whose purpose is to understand the historical processes that have outlined it from its regional origins, the evolution of urban processes and its built materiality, in perspective, where we come from and where we are going. It proposes to reveal the roots and implications of its materiality, which are reflected in a way of doing things, in its own ways of living, which raise several questions: Why is the city the way it is? What is the origin of these shapes? What makes it different from cities in other latitudes and even from the same region? How has your transformation been? What urban processes have outlined it? What are the implications of this materiality in the way of life of its inhabitants?The research is based on three methods of analysis: historical-regional, urban evolution and morphological. The first refers to the analysis of the regional context, from the colonization processes to the formation of new cities and the origin of some deep-rooted urban practices that reveal the roots of a regional identity. Secondly, the evolution approach studies the transformation of urban practices, ways of living and building, and forms of growth that change in identifiable stages over time. The morphological approach focuses on the urban residential fabric at various scales, revealing the ways of living and building, through the categorization of the different elements of the fabric: the home, the plot and the block.The treatment of these approaches is carried out through the analysis of three factors that constitute transversal axes of the study: territory, society and urban planning. The shape of the territory poses various challenges to urban growth, especially in a city like Tijuana, with a rugged topography. The social sphere has a life of its own, with cultural and lifestyle references that, in the case of Tijuana, is a city of migrants from different regions of the country, a recently created multicultural city. The role of urban planning is as an intermediary between territory-society and material construction, through the application of standards, policies and actions in the public sphere.The methodological structure is made up of desk work and field work. The first consists of documentary, statistical and cartographic analysis, whose main sources of information are urban studies of Tijuana, statistical, cartographic and photographic bases from different local, national and international sources. The field work consists of interviews with key actors, trips to different areas of the city for on-site observation, informal interviews with inhabitants and the creation of a photographic album. It is applied research that generates practical knowledge about specific areas, processes and interventions for urban planning. At the same time, the research is supported by a theoretical body that supports its findings, especially in a characteristic approach of the studies developed in the Department of Urbanism and Territorial Planning of the Barcelona School of Architecture.One of the main contributions of the study is found in its morphological approach that provides a base drawn at different scales of the physical structuring of the city that allows a better understanding of the parts that compose it, and in turn, its materiality as a whole. In general, the study provides interdisciplinary and theoretical-practical knowledge as a starting point for intervention, for the proposal of urban transformation, regeneration and rehabilitation projects, especially of the residential fabric, as well as elements of reflection for the construction of a city model of its own, a thoughtful city.
  • TSIOUTI, ANDRI: Generando patrimonio a partir de los escombros. La recuperación de los paisajes mineros en España
    Author: TSIOUTI, ANDRI
    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: Department of Urbanism, Territory and Landscape (DUTP)
    Mode: Normal
    Deposit date: 10/07/2024
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: SABATE BEL, JOAQUIN | PESOA MARCILLA, MELISA
    Committee:
         PRESIDENT: LLOP TORNE, CARLOS JUAN
         SECRETARI: SALVÀ MATAS, CATALINA
         VOCAL: ARRIBAS NAVARRO, LUIS DIEGO
         VOCAL: ROMÁN LÓPEZ, MARIA EMILIA
         VOCAL: MATIAS RODRIGUEZ, ROBERTO
    Thesis abstract: The purpose of this research is to analyze the processes of reclamation of mining areas in Spain. A systematic review of the literature on this matter shows that, although there are numerous publications addressing different ways to intervene in these places, most explain the interventions in an isolated and generic manner, or as specific cases, without analyzing the entirety of the processes employed as systems of successive stages. These studies also do not pay enough attention to how changes between different stages have occurred, the factors that have influenced the transition from one trend to another, or the shift from rejection to appreciation of the mining landscapes. All of this marks the starting point of this thesis, in which we aim to uncover the processes followed in the reclamation of mining areas and to observe the changes in attitudes that have occurred from one trend to another. This would be its main contribution.By exploring the main ideas and theories that have marked the path towards the reclamation of mining spaces, we highlight how long it has taken to understand them as cultural heritage in Spain. Its recognition dates back only three or four decades, during which, however, significant advances have been achieved and unique projects have taken place.In the thesis, we demonstrate how different dimensions have been incorporated into the reclamation processes, starting from pioneering cases—preceding the more common and legally required interventions—to other reference examples. We analyze the identified processes to reveal how progress has been made, from the initial demands for adequate environmental conditions to the recognition of mining heritage and the appreciation of mining traces. We particularly focus on how the cultural dimension has been integrated into the mining reclamation processes, from the early, relatively small-scale interventions to larger projects that incorporate numerous remnants related to that activity, culminating in the creation of territorial parks. We highlight the moment when the reclamation of mining areas, previously carried out due to legal obligation or the mining companies' initiative, became a social demand aimed at fostering local development. We also consider the valorization of the geological interest of many mining sites and their reclamation as a result of that progress.We defend the representativeness of the case studies, verifying that, although they are exceptional considering the numerous abandoned mines, they end up setting a clear trend while also being representative of the reclamation processes that could be applied in similar contexts. We uncover their components and the patterns that repeat in many of them, establishing guidelines for future projects and offering lessons on the factors that ensure weaknesses do not hinder the reclamation of mining landscapes but instead promote their revaluation and use for the common good.

Last update: 26/07/2024 04:45:23.