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Theses authorised for defence

  • MARTÍNEZ MÉNDEZ, MIGUEL: Relación entre la Cultura Organizacional dominante y los Estilos de Liderazgos en la Policía de Puerto Rico
    Author: MARTÍNEZ MÉNDEZ, MIGUEL
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme:
    Department: Department of Engineering Design (PE)
    Mode: Normal
    Deposit date: 25/06/2014
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: FIGUEROA GONZÁLEZ, JOSE MANUEL
    Committee:
         PRESIDENT: TEJEDOR CALVO, SANTIAGO
         SECRETARI: GONZALEZ BENITEZ, MARIA MARGARITA
         VOCAL: ARZAMENDI SÁEZ DE IBARRA, JESÚS
    Thesis abstract: Historically, theorists have attempted to develop an effective leadership model from the great man theory to present day philosophical leadership concepts. Present day theorists continue to identify and define transformational leadership as an effective leadership style in which leaders motivate subordinates' commitment to organizational goals, vision, and mission by empowerment them to take action in pursuit of organizational effectiveness. This effort to increase organizational effectiveness is also evident in industrial-organizational psychology's history with the work of the Gilbreths (1917) and Henry Ford 1913 on the USA vehicle industry Shenhow (1999).This paper investigates the relationship between organizational culture and the style of leadership in the Puerto Rico Police Department. Organizational culture is often an important factor influencing the competitive strength of any organizational entity. Leadership is also a critical component in the success an organization. It is important to understand how these two powerful determinants of organizational performance, culture and leadership, affect each other. Research determining that specific types of organizational culture favor particular styles of leadership is important as it aids organizational leaders to identify which styles of leadership are more likely to be successful in their culture. Furthermore, organizations wishing to change leadership styles may have to first modify their culture to support different leadership styles. This study uses the Competing Values Framework to define the organizational culture as clan, adhocracy, hierarchy, or market. Leadership style is defined as transformational, transactional, or laissez faire. Organization culture is measured using the Organizational Culture Assessment Instrument and the leadership style is determined by the MLQ 5X survey. Pearson's correlation and regression is used to determine the relationship between the variables. The results of this study indicate there is not a significant relationship between the dominant types of organizational cultures and leadership styles. Transactional, transformational and laisser-faire leadership styles were not significant statistical correlational found in hierarchy cultures.

DOCTORAL DEGREE IN AGRI-FOOD TECHNOLOGY AND BIOTECHNOLOGY

  • MIRAZIMI, FARNAZ SADAT: Personalized meal by using different proteins based on 3D printing
    Author: MIRAZIMI, FARNAZ SADAT
    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 AGRI-FOOD TECHNOLOGY AND BIOTECHNOLOGY
    Department: (DEAB)
    Mode: Normal
    Deposit date: 21/12/2022
    Reading date: 19/04/2023
    Reading time: 11:30
    Reading place: Saló de graur Escola d'Enginyeria Agroalimentària i de Biosistemes de Barcelona.Ed. D4, Campus del Baix Llobregat de la Universitat Politècnica de Catalunya, C. Esteve Terradas 8, 08860 Castelldefels.
    Thesis director: SALDO PERIAGO, JORDI | PUJOLA CUNILL, MONTSERRAT
    Committee:
         PRESIDENT: CAPELLAS PUIG, MARTA
         SECRETARI: MINGUELLA CANELA, JOAQUIM
         VOCAL: SAGUER HOM, MARIA ELENA
    Thesis abstract: Currently, the use of 3D printing technology in the food sector is being considered, which can improve or displace some of the traditional methods of food manufacturing. The 3D printing market has grown significantly and is poised to grow in line with the digitization and robotization of manufacturing. This technology can allow relocation of food preparation and personalize diets adapting them to the personal needs of everyone (malnutrition, swallowing problems, diets for the elderly, athletes, children, pregnant women...). On the other hand, we find ourselves with the problem of the scarcity of resources due to population growth and obtaining food through current production systems that will need to be revised to reduce the carbon footprint and energy consumption. Another factor to consider is also the waste generated during production, transformation and consumption. The use of personalized nutritional formulations from printable ingredients could be a solution, although it is still a challenge.The main objective has been to design different formulations of protein-enriched mashed potatoes for personalized diets. For this, different formulations of mashed potato enriched with soy protein (SPAH) were designed at different concentrations (3%, 5% and 7%) together with 0.2% agar to study their ability to be printable for using by people with dysphagia. In addition, the effect of different proteins (soy, cricket and egg albumin) at concentrations of 3% and 5% in the formulation was evaluated through the evaluation of their rheological characteristics (viscosity, thixotropy, creep and viscoelastic behavior), textural characteristics (TPA (Texture Profile Analysis), force of extrusion and back-extrusion), ability to be printed and sensory characteristics (hedonic and sensory evaluation).Of all the formulations tested, it was obtained that the best capacity to be printed was achieved in the sample with 5% soy protein and 0.2% agar, which presented values of yield stress (1489 Pa) and storage modulus (1352 Pa. s). All the samples of puree enriched with SPAH presented a noticeable increase in viscosity and elastic limit, which favors its impression.According to the IDDSI (International Dysphagia Diet Standardization Initiative) test, all samples (with SPAH and agar) were suitable for use in people with dysphagia problems. On the other hand, it was observed in all the formulations used that not only the rheological properties such as yield stress and viscoelastic behavior, but also the texture test, such as force of extrusion and back-extrusion, can be correlated with printability. The force of extrusion test with firmness and consistency results in a minimum range of (0.03 N) and (0.40 N·s) respectively, allow favorable 3D printing. Of the formulations used, those containing soy and cricket protein with values of firmness and consistency between the range of (0.03 ¿0.04 N) and (0.40¿0.52 N·s), respectively, presented great stability even for complex shapes. while the formulations with egg albumin could not achieve this stability due to the fact that the interlocking networks were very weak, presenting significantly lower rheological and textural values. The puree enriched with cricket protein and SPAH showed good mechanical properties for printing and self-supporting, but SPAH protein was not acceptable due to the taste and odor induced by the acid hydrolysis process, but in most cases the attributes sensory (firmness, thickness, smoothness, rate of breakdown, adhesive, and difficulty swallowing) were positively correlated with instrumental parameters and 3D printing. In conclusion, in this thesis, it has been shown that the enrichment of mashed potatoes with different proteins (soy, cricket) for 3D printing is feasible. This allows the customization of fortified foods for people with special needs.

DOCTORAL DEGREE IN APPLIED MATHEMATICS

  • MIRZA, WALEED AHMAD: A theoretical and computational study of the active self-organization of nematic patterns in thin cytoskeleton layers and their effect on curvature.
    Author: MIRZA, WALEED AHMAD
    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 APPLIED MATHEMATICS
    Department: (DECA)
    Mode: Normal
    Deposit date: 21/12/2022
    Reading date: 16/02/2023
    Reading time: 10:30
    Reading place: Sala d'Actes de l'FME, Edifici U, Campus Sud
    Thesis director: ARROYO BALAGUER, MARINO
    Committee:
         PRESIDENT: TURLIER, HERVÉ
         SECRETARI: ORIOLA SANTANDREU, DAVID
         VOCAL: ERZBERGER, ANNA
    Thesis abstract: The structure and dynamics of important biological systems, ranging from cytoskeletal gels to tissues, are controlled by an interplay between activity, dissipation, nematic order, density, and geometry. In particular, the actin cytoskeleton is remarkably adaptable and versatile and self-organizes into a variety of architectures, notably dense nematic structures. Examples of such structures are contractile rings to accomplish cell division and wound healing, or stress fibers playing an essential role in cell spreading, force generation, and migration. However, the mechanisms leading to dense nematic bundles remain poorly understood and to our knowledge, no prior theory explains their mesoscale self-assembly. Previous hydrodynamic approaches to active nematic systems have focused on incompressible liquid crystals. However, these models are not pertinent to actin gels, which are highly porous and exhibit very large density variations controlling activity gradients and active flows. Furthermore, porous actin networks can exhibit extended isotropic states without defects, and nematic order is presumably induced by flows and active mechanisms rather than by crowding. Finally, little attention has been paid to the formulation of active nematics on deformable surfaces and to a general computational framework to address such complex problems. Finally, we lack a unified understanding of actin network polymorphism, and more specifically of the physical mechanisms that enable a single active material to adopt very different network architectures with distinct cellular functions. To address these challenges, we develop a variety of theoretical and computational models for active nematic gels. In part I of the thesis, we focus on active nematic gels confined to a plane. We develop a transparent modeling framework for density-dependent active nemato-hydrodynamics based on Onsager¿s variational formalism, according to which the dynamics result from a competition between free-energy release, dissipation and activity. We also develop a numerical finite element method based on a time-incremental version of Onsager's formalism, which inherits the nonlinear stability and thermodynamic consistency of the continuum principle. We use this numerical approach to study the assembly of a contractile ring during wound healing and the defect dynamics in a confined colony of contractile cells. We next study the active self-assembly of nematic patterns from a uniform and quiescent gel using linearized theory and nonlinear simulations. We establish the conditions for nematic bundle formation and how active gel parameters control the architecture, connectivity and dynamics of self-organized patterns of nematic bundles. Finally, using discretenetwork simulations, we substantiate the major requirements for active nematic self-organization according to our theory. We thus provide a framework to understand the emergence and dynamics of mesoscale nematic organizations in actin networks. In part II of the thesis, we develop a general model for active nematic gels on deformable surfaces. Again, Onsager's nonlinear formalism provides a simple method to transparently develop complex models. The resulting system tight couples shape dynamics, nematic dynamics, density dynamics, and interfacial hydrodynamics. We exercise this model to understand the self-organization of the cytokinetic ring using an axisymmetric numerical formulation. Finally, we provide a general 3D computational approach and apply it to an inextensible active liquid crystalline deformable surface. We examine the interplay between the motion of nematic defects and shape.

DOCTORAL DEGREE IN ARCHITECTURAL DESIGN

  • CASTILLO FUENTEALBA, CARLOS IGNACIO: Interior-exterior en arquitectura
    Author: CASTILLO FUENTEALBA, CARLOS IGNACIO
    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: 04/11/2022
    Reading date: 13/02/2023
    Reading time: 11:00
    Reading place: Sala de Graus ETSAB - UPC Campus Sud - Av Diagonal 649, 08028 Barcelona
    Thesis director: SOLAGUREN-BEASCOA DE CORRAL, FELIX
    Committee:
         PRESIDENT: FERRER FORES, JAIME JOSE
         SECRETARI: GASTON GUIRAO, CRISTINA
         VOCAL: FERNANDEZ ELORZA, HECTOR DANIEL
         VOCAL: LABARTA AIZPUN, CARLOS
         VOCAL: PALOMARES FIGUERES, MAITE
    Thesis abstract: The purpose of the doctoral thesis is to study interior spaces - built in the old tradition of closed and contrasted architecture ¿ relativized in their interior condition. In the classical opacity and the difference between the inside and the outside, we find a different relationship to the so-called "fluid space" of modernity, between the interior and the exterior condition. The first part approaches a conceptual definition of the topic, understanding the interior-exterior as the construction of an interior and, simultaneously, an exterior experience, of opposite tendency in the intimacy of confinement. Reviewing from the intemperie, that manufactures the intrusion of atmospheric phenomena in the enclosed space, to a more unprejudiced and heterogeneous way of understanding the interior as exterior.The body of the thesis is divided into three maps (or parts) that grasp the interior-exterior from an independent point of view, studying the treatment of its limits, but with the constraint of always beginning the story in Mediterranean interiors, to continue in Germany, and culminate mainly in the architecture of Nordic neoclassicism in Sweden and Denmark. Together, they make up the observatory proposed by the Thesis, overlapping in a single cartography that follows the reverse orientation left by the displacements of Northern European architects to the classical world.Within each map, the interiors are ordered according to two simultaneous criteria: firstly, a thematic perspective. And, secondly, a geographical disposition with a northerly direction. The interiors are progressively linked to explain the proposed argument and each interior space presupposes the explanation of the previous one. Moreover, the three maps follow a sequential order, although each one has enough individual nature for non-linear reading.The first map revisits the maximum exteriority that defines the symbol of contained universal space and the vertical tendency of the enclosure, finding its revelation in the infinite staircase. The second map traces the dome and the tent in the romantic garden, both suspended within traditional roofs, hidden among trees of picturesque outdoor promenades. Finally, the third map explores inductively the things, inventorying elements that, placed inside, relativize the interior and approach the ambiguity of an internal landscape.The winter climate conditions the architecture of Northern Europe and the need for covering establishes a dialectical relationship with the exterior experience and also with the repetition and interpretation of the admired classical interiors, increasing, by contrast, the exterior condition of its interiors.

DOCTORAL DEGREE IN ARCHITECTURAL, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY

  • HABIBI, SAEID: Low-cost intelligent refurbishment of façades. A study of Barcelona public school building façades
    Author: HABIBI, SAEID
    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: Article-based thesis
    Deposit date: 16/12/2022
    Reading date: 01/02/2023
    Reading time: 10:30
    Reading place: Enllaç públic per a la connexió a la videoconferència/Enlace público para la conexión a la videoconferencia/Public link for the videoconference:meet.google.com/snc-qkei-swt
    Thesis director: PONS VALLADARES, ORIOL | PEÑA VILLAMIL, DIANA MARITZA
    Committee:
         PRESIDENT: ARMENGOU ORÚS, JAUME
         SECRETARI: HAURIE IBARRA, LAIA
         VOCAL NO PRESENCIAL: SAELI, MANFREDI
    Thesis abstract: Due to the fact that construction, maintenance, and operation of buildings consume almost 40% of global energy today, architects play a major role in the reduction of world energy consumption. Building¿s façades can have a significant and measurable impact on the economic, environmental, and social performances by edifices, and their retrofit is seen as a key solution to the problem of today¿s aging building stock. Concerning overheating and the potential loss of internal heat, transparent parts of the building façade have a large effect on the building¿s energy consumption. Within this context, the use of intelligent systems on architecture envelopes can fulfill contemporary demands as promising solutions regarding energy efficiency, emissions, or the degree of visual contact in building environments.In Spain, boom periods of construction combined with typical building styles of each period, have resulted in a large stock of aging educational buildings at risk of structural vacancy and obsolescence. Despite their lack of insulation, high air infiltration, and solar gain, many such edifices from the 1970s-1980s are still in use today. Moreover, the majority of today's buildings will still be in use in 2050 based on the Spanish edifices' annual replacement rate of 3% according to the European Commission.The main objective of this Ph.D. thesis is to analyze, develop and promote intelligent services to existing façades to optimize these buildings' economic, environmental, and social sustainability performances through a holistic and innovative sustainability assessment model.To do so, the first phases of this thesis, the author carried out a deep documental investigation on more than 800 research articles regarding intelligent façade systems, advancements in material engineering, user demands, automations, and their sustainability performance following the preferred reporting items for systematic reviews and meta-analyses reporting standards. Based on the results from preliminary investigations, different low-cost and environmental-friendly dynamic façades have been prototyped in the context of the Spanish public schools targeting pupils' academic progress through optimizing the lighting and thermal comfort levels. These prototypes have been developed by employing municipal solid waste materials during participatory workshops with school pupils. This concept is expected to promote awareness and better management of our society's critical waste generation by returning waste to the reusing cycle.From the data collected, researchers found that intelligent façade design and application result from a complex decision-making process. The cost and long-term nature of the investment mean that the façade decision is strategic. Accordingly, the next phase examined the actuality of intelligent façade projects in practice through conducting in-depth exploratory methodologies and tools for analyzing, evaluating, and designing among the incorporation of interdisciplinary experts in the topic. Finally, the last phase experimentally monitored and tested the developed prototypes and other test samples of various waste items.The findings show that the process of façade retrofit that fulfills the school building functioning, energy performance, emissions, costs, and appearance, requires the realm of the profession. The members involved in the retrofitting projects of public primary school buildings mainly had to make initial façade design decisions based on ideas resulting from cognition and drawing on experience. This thesis and its subsequent conceptual framework provide a new overview of waste-based construction materials and their introduction to developing intelligent façade technologies, through scientific indexes that can be useful for occupants, builders, architects, and policymakers to have a good understanding of the potential contributions that intelligent façades provide.
  • MILAN, CAIO CESAR: Estudio numérico y comparativo del comportamiento de columnas tubulares mixtas con un pretensado inicial de uno de los componentes. Aproximación experimental del comportamiento de secciones CFST pretensadas, sometidas a compresión cíclica.
    Author: MILAN, CAIO CESAR
    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: 13/12/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: MARISTANY CARRERAS, JORDI | ALBAREDA VALLS, ALBERT
    Committee:
         PRESIDENT: ROMERO GARCIA, MANUEL LUIS
         SECRETARI: RETAMALES SAAVEDRA, RODRIGO ALFONSO
         VOCAL NO PRESENCIAL: IGLESIAS TOQUERO, GORKA
    Thesis abstract: The use of mixed structures of the most varied types and typologies, mainly in steel and concrete, have been increasingly used in the recent decades. The mechanical advantages of these structures in comparison with conventional reinforced concrete and steel structures working independently, allow to optimize the performance of both components.Within all the possibilities of composite structures, this investigation focuses on the study of composite columns of circular tubular steel profiles filled with concrete (CFST). CFSTs are increasingly used due to improved structural performance, especially under compression. This is basically due to the confinement effect provided by the pipe, which generally improves the ductility and strength of the concrete fill. Mainly, a series of issues derive from the construction process of these sections, such as, for example, the fact of loading the tube before concreting in preliminary construction stages causes a preloading effort that implies a different response from the section than expected. These problems must be considered in the design process and lead to unwanted preload effects in one of the two components derived from the process itself.A limited number of studies treat preloading as a design method in itself before being under service loads (active methods) to improve the capabilities of CFST sections. Therefore, the thesis begins by analyzing and comparing 4 different methodologies (2 passive versus 2 active preload methods) describing the potential benefits and consequences of them throughout the section; while sometimes a prestress ratio in a component can improve the overall mechanical response, sometimes it doesn't and even becomes detrimental. The relation of the confinement effect on the core and especially when activated reveals the degree of real improvement of the compressive response of the section in terms of ductility and resistance.Finally, for the method that has been considered most beneficial, a small experimental campaign was carried out so that there is a first approximation of the behavior of this type of preloaded section.

DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION

  • CHAMORRO HERNANDEZ, WILLIAM OSWALDO: Event based SLAM
    Author: CHAMORRO HERNANDEZ, WILLIAM OSWALDO
    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: Institute of Robotics and Industrial Informatics (IRI)
    Mode: Temporary seizure
    Deposit date: 07/12/2022
    Reading date: 17/02/2023
    Reading time: 16:00
    Reading place: ETSEIB_ Aula Capella de l'Escola Tècnica Superior d'Enginyeria Industrial de Barcelona (ETSEIB), Av. Diagonal, 647. 08028 Barcelona. Enllaç videoconferència: meet.google.com/iki-vfba-aai
    Thesis director: ANDRADE CETTO, JUAN | SOLÀ ORTEGA, JOAN
    Committee:
         PRESIDENT: GALLEGO BONET, GUILLERMO
         SECRETARI: AGUDO MARTÍNEZ, ANTONIO
         VOCAL: CIVERA SANCHO, JAVIER
    Thesis abstract: Event-based cameras are novel sensors with a bio-inspired design that exhibit a high dynamic range and extremely low latency. They sensing principle is different than the one of conventional cameras. These novel sensors generate asynchronous streams of events triggered proportionally to the logarithmic pixel-level change of brightness.Each event is timestamped with a micro-second resolution and transmitted as soon as it is fired. Thus, event cameras convey non-redundant information and capture fast motion. These assets make them suitable for high dynamics and challenging lighting applications without image blurring, over or underexposure problems. The event camera's operational principle requires new algorithms to deal with image intensity's absence and leverage its fast asynchronous response.This thesis explores new event-based monocular solutions to the localization and mapping problem (SLAM) in human-made scenarios. Concerning the event camera's natural edge response, the use of line features was evaluated throughout the chapters of this thesis.A high-speed camera pose tracking approach was proposed that exploits the fast response of an event camera to accurately estimate its 6 degrees of freedom. Lines are efficiently matched to the events with a proposed fast data-association mechanism. In the tracking formulation, event-per-event and window of events representations were analyzed to identify their advantages and real-time implementation feasibility without introducing speed bottlenecks. Additionally, several estimation variants were implemented regarding measurement and motion models.This thesis also analyzes sensor fusion methodologies to combine events with inertial data. The inertial measurements come at a lower rate than events; thus, the objective is to avoid conventional inertial integration and cooperate with the event data to correct state parameters. The sensorial fusion allowed more accurate estimations but slowed down and constrained the motion dynamic and event-data rate to the inertial sensor capabilities.Finally, the proposed mapping approach leverages the natural edge highlighting of events to recover and optimize straight lines in human-made scenarios. Line-based reconstructed maps have better representativeness for some tasks than point clouds since line features provide a notion of connectivity, boundary and a sense of neighborhood. In this work mapping and tracking strategies are executed in parallel threads, that add to the map new detected lines as the camera moves while updating the old ones with incoming observations.All variants tested in this thesis for tracking and sensor fusion are compatible with the mapping thread and can be combined freely as best suited for determined experimental conditions.The main contributions of this work are three-folded: (1) event-based camera pose tracking aiming at high dynamics and challenging lighting conditions, (2) event data and inertial measurements fusion with the primary objective of preserving the event camera's fast response characteristic, and (3) event-based tracking and mapping system with line features in real-time for human-made environments. It is shown that monocular-based event-line SLAM can perform in challenging scenarios with a high level of accuracy and real-time performance, where conventional frame-based methods cannot operate.These thesis' contributions were validated through extensive experimentation with real data in different scenarios and with different degrees of motion aggressiveness. Appropriate comparison against state-of-the-art SLAM approaches were included.
  • PLANA RIUS, FERRAN: Shedding Light on Sewer Pipes: Deep Learning Perception Approaches for Autonomous Sewer Robots
    Author: PLANA RIUS, FERRAN
    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: Temporary seizure
    Deposit date: 11/01/2023
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: MIRATS TUR, JOSEP MARIA | CASAS GUIX, MARC
    Committee:
         PRESIDENT: ANDRÉS DOMÉNECH, IGNACIO
         SECRETARI: CEMBRANO GENNARI, M.GABRIELA ELENA
         VOCAL: LOPEZ PENA, ANTONIO MANUEL
    Thesis abstract: Sewerage is a vital infrastructure for society¿s day-to-day life. Its maintenance is a priority and current European legislation increases the demand of a proper inspection. Being a complex access and dangerous environment, it complicates its inspection. Using teleoperated robots, a video of its interior is obtained. However, the operator report is highly subjective. The company INLOC Robotics SL offers a solution to make an automatic report using CCTV videos called SEWDEF. This thesis focuses on improving this system by focusing efforts on the integrated Convolutional Neural Networks (CNN).In this sense, we explore how CNNs work, putting efforts to understand how information is encoded within them. How they learn, what they learn and how to improve it. In the analysis carried out we realize that CNNs are not used to their full potential. There are several causes for that, from the lack of data to the CNN architecture used. However, in this thesis we aim to optimize the available data and CNN.In order to achieve this goal, the field of Curriculum Learning (CL) is explored. This field proves that by alternating the order in which images are fed to the training loop, results can be improved compared to a standard training regim. Exploring this idea, the Tracking Networks Self-Curriculum (TNSC) method is designed. It consists on training networks called Tracking Networks that help us find out in which order images are learned. This order can be used as a samples¿ difficulty measure and thus design a curriculum to train CNNs. Tested networks results improve, confirming that in the sewer field CL techniques are applicable. However, the method is complex and does not solve the situation for all the tested defects. For this reason the latent space is explored.The latent space is a high dimensional space that belongs to the CNN top layers, before the prediction layer. In this space we find encoded and compressed information about the input image characteristics. The thesis explores this space using Autoencoders (AE), self-supervised neural networks trained to reconstruct an input image after passing through an information bottleneck. Studying the latent space we can see that it contains relevant information, including about specific defects, that can be used in other tasks.Using the knowledge acquired, we develop a method called Supervised Latent Curriculum with SOM tree (SLCS). The method is based on performing a clustering of the latent space using the Self-Organizing Map (SOM) method. Instead of implementing a single SOM model, smaller models are used where at each iteration the clustering becomes more specialized through new models. This division allows us to create a difficulty measure for the samples that belong to the latent space. This measure can then be used to create curriculums that can be used to train CNNs. Results prove that the SLCS method is feasible. In most cases it outperforms the TNSC method and still has a lot of room for improvement.As a main conclusion we can draw that the two designed methods based on CL improve the INLOC Robotics SL SEWDEF system. It is also shown that altering the training order is able to improve the results of CNNs. In addition, a way has been found to use the latent space to design a difficulty measure.

DOCTORAL DEGREE IN CIVIL ENGINEERING

  • CABRERA VELEZ, ESTEBAN: Metodología para estimación del daño sísmico en edificios en base a modelos numéricos avanzados y a monitorizaciones RAR
    Author: CABRERA VELEZ, ESTEBAN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN CIVIL ENGINEERING
    Department: (DECA)
    Mode: Normal
    Deposit date: 03/10/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: GONZALEZ DRIGO, JOSE RAMON | LUZI, GUIDO
    Committee:
         PRESIDENT: ROCA ADROVER, ANTONI
         SECRETARI: PUJADES BENEIT, LUIS GONZAGA
         VOCAL: NAVARRO BERNAL, MANUEL
    Thesis abstract: In post-seismic scenarios, the rapid and safe evaluation of structural damage is essential to develop an effective response during the recovery, rehabilitation and reconstruction stages. The development of new inspection tools based on the use of remote sensors that make access to the interior of damaged buildings unnecessary, thus safeguarding the lives of technicians, is promising. This thesis work investigates the feasibility of using natural vibrations to detect the structural health status of buildings, in order to distinguish structurally unsafe or unstable states from safe configurations. The theoretical basis underlying the research is that the modal properties of buildings change with damage accumulation. Three axes structure the proposal to develop new safe and rapidly applicable inspection tools: i) Advanced numerical modelling of buildings in three dimensions (3D); ii) The application of advanced methodologies for assessing the vulnerability, fragility and seismic damage of structures: iii) The use of original and novel technology based on microwave interferometry and using a real aperture radar (RAR), for the remote measurement of vibrations in structures excited by ambient noise. The object of study has been medium-rise housing constructions belonging to one of the most common construction typologies in Spain, such as reinforced concrete buildings with waffle or unidirectional slabs and with an inner wall system built with hollow ceramic brick masonry. As case studies, two buildings affected by the earthquake (Mw 5.1), which occurred in Lorca on May 11, 2011, and an operational building located in Barcelona have been selected. The methodology used to estimate the vulnerability and damage states observed in these buildings are those considered as standards in advanced seismic risk analysis programs. The necessary calculations to evaluate the modal behaviour, as well as the structural performance against specific seismic demands, are the capacity spectrum method and the incremental dynamic analyses applied using advanced numerical models of the buildings and taking into account the directionality of the seismic action. Based on the structure analysis software used, an original and practical methodology is proposed to obtain the damage index of the structure that can be evaluated at each step of the incremental lateral pushover analysis. This methodology obtains a damage index based on the results stored by the calculation software at each stage of the pushover analysis. The results of this proposal have been satisfactorily compared with the damage indices obtained using other advanced methodologies. Other remarkable results have been obtained studying the variation of the modal parameters with the accumulation of damage. The variations of the fundamental periods have proven to be a good indicator of the accumulation of damage. The variation of mass participation factors with increasing damage has also been explored. Numerical models of the same building having different accumulations of earthquake damage have been generated. This has made it possible to compare the damage configurations with the configuration of the healthy operational building and to identify and quantify the contribution of the non-structural inner walls in the dynamic behaviour and the resistance capacity of the building. A general conclusion is that RAR technology, non-invasive and remote, can contribute to substantially reduce inspection times and mitigate the risk for inspectors and technical teams during the evaluations of buildings in post-seismic scenarios or damaged by other natural or anthropogenic causes.

DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING

  • BALOOCHI, HANI: Use of alternative materials in soil stabilization: mechanical and environmental aspects.
    Author: BALOOCHI, HANI
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING
    Department: (DECA)
    Mode: Article-based thesis
    Deposit date: 17/11/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: BARRA BIZINOTTO, MARILDA | APONTE HERNÁNDEZ, DIEGO FERNANDO
    Committee:
         PRESIDENT: VAZQUEZ RAMONICH, ENRIC
         SECRETARI: LÓPEZ GAYARRE, FERNANDO
         VOCAL: FORMOSA MITJANS, JOAN
    Thesis abstract: Currently, the two most raw material consumer industries are civil engineering and the pulp and paper industry. Meanwhile, these sectors face severe criticism due to their environmental impact. Additionally, by increasing more strict regulations over the disposal of pulp and paper waste into landfills, European unions are looking for the possible use of different applications of paper ash.This doctoral thesis is a part of the European Union project (Paperchain), which has the participation of 20 European partners (Spain, Portugal, Sweden, Slovenia, and France), which include construction companies, paper companies, research centres, and universities. This thesis aims to study the possibility of using waste paper fly (WPFA) and bottom ash (WPBA), which come from a recycled paper plant (energy recovery plant) in Spain. The goal is to use WPFA and WPBA as cementing materials to stabilize soil without incorporating any other traditional binder material. Therefore, an in-depth characterization of the two types of ashes (WPFA and WPBA) is carried out to determine their hydration process and strength gain. Also, when ashes are mixed with soils for stabilization, different amounts of binder, water and delay times for compaction of the samples are studied.Determining the environmental impact of WPA is an essential step to the safe use of WPA as binders. Hence, in the first place, the chemical, mineralogical, and size distribution of WPA during one year of sample collecting from the recycling paper plant was conducted. Then, release of pollutants from stabilised soils with WPFA is also studied by means of leaching test in the laboratory and the trial field.Cement and lime are prone to swell when becoming in contact with a sulfate source. Owing to similarities between the cement and WPA, the stabilized soil was placed in contact with different sulfate concentrations to determine the swelling and to assure its safe use. Finally, as most of the experiments were conducted in the laboratory, field experimental sections were carried out to verify the performance of stabilised soils with ashes.The chemical and mineralogical variation during the one-year sample collection from the paper plant demonstrated little changes in WPFA and WPBA. Hydration in both ashes is similar, when mixed with water, hydrated calcium silicates gel (C¿S¿H), portlandite and, in some cases, Friedel¿s salt are generated. This process is slower in bottom ash (WPBA) and therefore its mechanical performance is lower compared to fly ash (WPFA).The amount of water plays an important role in swelling and the final strength of stabilised soil. To achieve better workability and minimise swelling it is important to add 30-minute delay time after mixing soil, ash and water. In addition, to obtain the greatest workability, reducing the water content by one point of Proctor value improved the strength significantly. In relation to durability results, different sulfate concentrations and temperatures had no effect on the durability of stabilized soil with WPFA. At long ages formation of ettringite is observe, in very low quantities, possibly due to the consumption of all aluminium in the system.The environmental impact assessment of WPA showed stabilized soil can be categorized as inert material. However, it should be mentioned that WPFA solely released a high amount of barium (Ba). Environmental test carried out on the experimental field trial do not show any negative effects in the environment.Finally, from a mechanical, environmental, and durability standpoint it has been successfully demonstrated that the implementation of WPFA as the sole hydraulic binder is possible.

DOCTORAL DEGREE IN ELECTRICAL ENGINEERING

  • LI, MINGSHEN: Power Calculation Algorithm under Nonlinear Loads and Hopf Oscillator-based Synchronization Controller for Grid-forming Inverters in a Microgrid
    Author: LI, MINGSHEN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
    Department: (DEE)
    Mode: Normal
    Deposit date: 05/12/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: MATAS ALCALA, JOSE | GUERRERO ZAPATA, JOSEP MARIA
    Committee:
         PRESIDENT: GUAN, YAJUAN
         SECRETARI: MARTIN CAÑADAS, MARIA ELENA
         VOCAL: AGUNDIS TINAJERO, GIBRAN DAVID
    Thesis abstract: In the grid-forming control of microgrids, the droop control is a widely used for the parallel operation of power inverters, but has some peculiarities as slow dynamic and inaccuracy in the power sharing. In the droop control, the power calculation of the active and reactive powers determines the speed of the controller capability to share linear and nonlinear loads. Therefore, the thesis address first the design of advanced filters to improve the dynamic response for droop-based inverters. And, a fast and accurate power calculation technique is proposed for three-phase inverters by using a two-stage combined Second Order Generalized Integrator (SOGI) approach to overcome this obstacle. The two-stage combined SOGI filter structure achieves the average active and reactive powers, used as the kernel for the droop-method operation. A small-signal model of a paralleled three-phase inverters is developed for determining the dynamic response of the system, which shows that the proposal is faster than the conventional droop method when both methods are designed under the same conditions. The proposal can be used to improve the stability and transient response of droop-operated inverters.After, a novel synchronization method based on Andronov-Hopf oscillators is proposed for driving paralleled single and three-phase power inverters, which show to have lower harmonics, faster dynamic response, and higher synchronization speed than the achieved by previous nonlinear Van der Pol oscillators, used as virtual oscillator controllers (VOC). The coupling strength between Hopf oscillators relies on the local feedback of the output current, which is able to synchronize with the rest of parallel inverters, without using communications. The Hopf equations considering the current feedback generates the voltage reference for the power inverters, and has a dual-loop that is designed in a static reference frame. The Hopf has a pre-synchronization stage that allows a softer connection of additional inverters. A small-signal state-space model for two parallel VSI is built and compared with a standard droop controller. The root locus exhibits a larger stability margin and lower parameter sensitivity. Finally, a grid-forming controller based on the Hopf oscillator is proposed that is able to synchronize and achieve accurate power tracking of the references. The Hopf model is analyzed and the synchronization region is obtained by using the Arnold tongue method. In this controller, the active power can be regulated by phasor, and a PI regulator is introduced in the reactive loop to control the amplitude voltage based on the Q - V relationship achieved by the Hopf.Matlab/PLECS simulation studies and experiments on a single phase and three-phase inverters platform are conducted in a microgrid laboratory to verify the proposed control strategies. The simulations of the proposed power calculation method presents a faster and more accurate performance when sharing nonlinear loads compared with the LPF-droop. In the case of the Hopf oscillator, the simulation and experimental results demonstrate a faster transient response and better robustness compared with the standard droop controller, and a wider operating range compared with the Van der Pol VOC.The Thesis has been organized in five sections: Section 1 introduces the background, state of the art, objectives, methodology, contributions and limitations of the work; Section 2 describes the proposed power calculation method using the combined SOGI filters approach; Section 3 is devoted to the Hopf oscillator control operating in an islanded microgrid; Section 4 describes the desing of the Hopf oscillator to operate with grid forming inverters; Section 5 is devoted to conclusions and forecast future line works.

DOCTORAL DEGREE IN ELECTRONIC ENGINEERING

  • RILLO MORAL, FRANCESC IU: New Autonomous sensor system for the continous monitoring of the composting process from the inside
    Author: RILLO MORAL, FRANCESC IU
    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 ELECTRONIC ENGINEERING
    Department: Department of Electronic Engineering (EEL)
    Mode: Normal
    Deposit date: 11/01/2016
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: CASAS PIEDRAFITA, JAIME OSCAR
    Committee:
         PRESIDENT: BRETTERKLIEBER, THOMAS
         SECRETARI: QUILEZ FIGUEROLA, MARCOS
         VOCAL: CASAS NEBRA, ROBERTO JOSE
    Thesis abstract: The composting process is Nature¿s way of recycling organic wastes with a good quality organic fertilizer as a result. This process, though, needs of a thoroughly monitoring of temperature and humidity for a good resulting material. During this Ph.D thesis we developed a wireless temperature and humidity autonomous system that monitored from the inside of compost. The fact of measuring and transmitting from the inside implies the need of a protection for the circuit and an issue in the measure.Temperature suffers delays when measuring from the inside of a protection and, as such, we developed an algorithm, implementable on microcontrollers, to counteract the effects of first order step responses. The conditioning has been optimized in terms of components and consumption, obtaining a theoretical and experimental comparative between the classic conditioning and the use of direct interfaces.Commercial humidity sensors need to be in direct contact with the environment they are measuring, but that is not possible in compost since they can get damaged. That is why we designed a humidity sensor based on coplanar capacitive electrodes that can measure through a protection layer. Some theoretical models have been obtained for the physical optimization of both the sensor and the influence of the protective layer.Compost has never been characterised as a transmission environment, and as such, communications in compost are innovative. The heterogeneity of the material and its changes in humidity, temperature and density made the transmission complex. We found the proper frequency band to commercially work in compost and the RF transmission model in compost to estimate attenuation vs distance.
  • SALEHI, NAVID: Energy Management in Collaborative Power Electronics-Based Microgrid Integrated With Renewable Energies
    Author: SALEHI, NAVID
    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 ELECTRONIC ENGINEERING
    Department: Department of Electronic Engineering (EEL)
    Mode: Article-based thesis
    Deposit date: 28/11/2022
    Reading date: 08/02/2023
    Reading time: 11:00
    Reading place: EEBE - Campus Diagonal-Besòs. Sala polivalente del edificio A: A0.03. Dirección: Avda. Eduard Maristany, 16. 08019 - Barcelona.
    Thesis director: MARTINEZ GARCIA, HERMINIO | VELASCO QUESADA, GUILLERMO
    Committee:
         PRESIDENT: GUINJOAN GISPERT, FRANCISCO JUAN
         SECRETARI: EL AROUDI, ABDELALI
         VOCAL: ZUMEL VAQUERO, PABLO
    Thesis abstract: This thesis is introduced the research performed on microgrid applications, especially in cooperative operating mode. The research is conducted considering two main challenging aspects of microgrid operation over the last years. The reliable and optimum operation of microgrids is surveyed by focusing on: energy management systems, specifically in collaborative microgridoperation and robust power electronics interfaces.This thesis presents a comprehensive review of optimization methods for individual and community microgrids. In addition, different control strategies applied in microgrid systems are studied. The potential pros and cons of various control strategies are analyzed, and the background studies bring brilliant and smart solutions for optimal control in a networked microgrid.A supervised and unsupervised learning clustering is developed in order to control a networked microgrid consisting of industrial, commercial, and residential microgrids. The clustering algorithms are performed based on the maximum load demand and operating reserve of the microgrid. Furthermore, a component size procedure for dispatchable units in a networked microgrid ispresented. The proposed algorithm evaluates the component size considering the operating reserve of microgrids. To diminish the adverse effect of component size reduction on microgrids¿ reliability, the proposed reduced factor is modified by the peak load and correlation of load profile.Optimal operation, new topology, and new control methods for various power electronics interfaces for microgrid applications are presented in the following. The optimal operation of the LLC resonant converter is investigated considering the load variation and switching frequency. Then, a modified cascaded high step-up Z-source DC-DC converter with high voltage gain and low voltagestress is proposed. Eventually, a novel control method for a single-phase Z-source inverter is presented. A feed-forward neural network predicts the forced response of the generalized predictive control to enhance the transient performance of the inverter.

DOCTORAL DEGREE IN ENVIRONMENTAL ENGINEERING

  • GASPARINI, ANDREA: Experimental and numerical modelling of CO2 behaviour in the soil-atmosphere interface. lmplications far risk assessment of carbon capture storage projects.
    Author: GASPARINI, ANDREA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN ENVIRONMENTAL ENGINEERING
    Department: (DECA)
    Mode: Article-based thesis
    Deposit date: 07/02/2020
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: GRANDIA I BORRÀS, FIDEL | BRUNO I SALGOT, JORGE
    Committee:
         PRESIDENT: VOLTATTORNI, NUNZIA
         SECRETARI: FOLCH DURAN, ARNAU
         VOCAL: MAZADIEGO MARTINEZ, LUIS FELIPE
    Thesis abstract: CO2 geological storage is considered one of the options technologically viable in order to decrease the industrial emissions of this gas species that strongly contribute to the greenhouse effect in the atmosphere (IPCC, 2005). As naturally, oil and gas are stored in porous rocks that have the same key geological features required for CO2 storage, so CCS aim to recreate a natural process to trap carbon dioxide for millions of years into deep saline aquifer or depleted oil and gas fields. Episodic release of CO2 from underground can occur from either natural processes (i.e., mantle degassing, thermal decarbonation, volcanic areas) or industrial (geological storage of CO2, CCS). Because of leakage can occur at every step of a CCS project, monitoring assumes an important role not only during and after injection but also before in order to know the state of the entire site from deep underground (reservoir level) to surface. In this respect, the use of atmospheric dispersion numerical models helps predicting the dispersion of the CO2-enriched gas plume once emitted from underground and allows an accurate map of risk level through time under particular meteorological conditions. The aim of this PhD. project is to give a better understanding of CO2 behaviour in the unsaturated zone and its atmospheric dispersion. The results are obtained from experimental and numerical modelling of CO2 leakage from an artificial leakage site and from natural analogues applied to risk assessment for CCS sites. To reach the above-mentioned targets and to prove results, this research plan combines experimental activity on site and numerical modelling. The first part of the research plan consisted of a contribution in the PISCO2 project at the ES.CO2 facilities placed in Ponferrada (Spain). The objective of this project was to predict how the injected CO2 will move laterally and vertically in the unsaturated zone and to determine the critical parameters that will affect the ecosystems. This part has been published in a peer review journal and presented in an international congress.The second part of the PhD. project has focused on the study of two natural analogues in volcanic areas. Natural analogues provide evidences of the impact of CO2 leakage, for both sites two approaches have been followed: a) direct measurement of air concentration and b) numerical atmospheric modelling with the TWODEE2 code. The study of CO2 emissions in natural systems provides a valuable information on the assessment and quantification of potential risks related to underground carbon storage leakage. Emissions of CO2 are studied in a large variety of geological environments, i.e., sedimentary basins, active andnon-active volcanic areas, seismically-active regions, and geothermal fields. Because of the physics of carbon dioxide gas, e.g., colourless, odourless, higher density compared to air, its accumulation may result hazardous and even lethal for life. The objective of atmospheric dispersion modelling is to predict how will move the plume, generated by a leakage in natural degassing systems and CCS sites.Results obtained from this doctorate provide:¿Coupling experimental and numerical data in order to test new methods and/or numerical codes;¿New elements to the knowledge of CO2 behaviours in the unsaturated zone as seen at PISCO2;¿New clues on non-invasive monitoring techniques for CCS sites and natural analogues;¿The usefulness of studying natural analogues;¿The usefulness of the SAP system, as a good method to evaluate high gas emissions from underground;¿The efficiency of atmospheric modelling as a valuable methodology in the risk assessment;¿The importance of risk assessment maps in active degassing areas;¿The need of production of forecasting maps to evaluate dangerous scenarios.¿Numerical models (multiphase transport and atmospheric gas dispersion) are proved to be useful tools to predict gas behaviour inthe vadose zone and in the near-grou

DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING

  • JAQUÉS ADELL, IRENE: Visco-plasticity of zero-thickness interfaces with softening, and application to the study of fault reactivation.
    Author: JAQUÉS ADELL, IRENE
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING
    Department: (DECA)
    Mode: Temporary seizure
    Deposit date: 18/11/2022
    Reading date: 10/02/2023
    Reading time: 11:30
    Reading place: ETSECCPB - UPC, Campus NordBuilding D2. Classroom: 216
    Thesis director: CAROL VILARASAU, IGNACIO
    Committee:
         PRESIDENT: ALEJANO MONGE, LEANDRO
         SECRETARI: VAUNAT, JEAN
         VOCAL: GONZALEZ MOLANO, NUBIA AURORA
    Thesis abstract: In the current context of both energy and environmental needs, there has been an increase in activities related to extraction and injection of fluids in the underground. It is known that a possible consequence of these activities is the reactivation of faults and, therefore, there has recently been of growing interest to understand under what conditions these events may occur and to try to avoid them or minimize their effects. In this sense, the main aim of this thesis is to develop tools that can contribute to a better understanding of the geomechanical processes that take place during fault reactivation events, either when they occur naturally or are induced by any human activity. In the present thesis a methodology is proposed to identify when an instability may be triggered and, also, quantify the amount of energy released during the unstable process. Moreover, the methodology proposed can be applied in both mechanical and hydro-mechanical cases, which implies that instability may be generated by either mechanical actions or fluid injections/extractions. The numerical model is based on the Finite Element Method in which fractures are represented by zero-thickness interface elements equipped with constitutive laws based on Fracture Mechanics principles. In particular, the constitutive model used consists of the reformulation of an existing fracture-based interface constitutive law (Normal/Shear Cracking Model) in terms of visco-plasticity with Hardening/Softening. Two instability control strategies have also been implemented: (1) a new Indirect Displacement Control method based on the visco-plastic dissipation (IDC-Wvp) and (2) an adaptation of the Visco-plastic Relaxation method (VPR). Regarding the first one, it has been found that the method can only be easily applied in purely mechanical cases, and for this reason VPR has finally been the method used to model unstable cases including mechanical and hydro-mechanical.A procedure has been developed for identifying the occurrence of mechanical instabilities such as snap-back or similar sudden events. This procedure is based on the continuous tracking of the various types of energy dissipation occurring along the discontinuity at the level of the constitutive visco-plastic model. It has been found that when a mechanical instability takes place, a jump is observed in the dissipation diagrams, and a difference emerges between two types of visco-plastic dissipation: total VP dissipation and VP dissipation based on projected stresses. This difference turns out to correspond to the Viscous energy dissipated by the interface during the transit through the instability, and therefore it can be associated to the energy released by the unstable event.Finally, the methodology proposed in this thesis was verified through academic examples which represent different fracture mechanisms that can be produced in a geomechanical scenario. Moreover, some more realistic examples are also presented where instability is induced by the effects of fluid pressure or fluid flow.Overall this thesis tries to contribute to develop numerical tools for the assessment of fault reactivation problems, not only to identify the existence of an instability, but also to quantify the energy released in these processes, energy that then may be eventually linked with the earthquake magnitude.

DOCTORAL DEGREE IN MARINE SCIENCES

  • LATORRE PÉREZ, FRANCISCO: Population dynamics, interactions and evolution of marine microbes using genomic approaches.
    Author: LATORRE PÉREZ, FRANCISCO
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN MARINE SCIENCES
    Department: (DECA)
    Mode: Normal
    Deposit date: 29/09/2022
    Reading date: 03/02/2023
    Reading time: 11:00
    Reading place: ETCECCPB_ Sala d'Actes de l'Institut de Ciències del Mar. Passeig Marítim de la Barceloneta, 37-49 08003 Barcelona
    Thesis director: LOGARES HAURIE, RAMIRO ERNESTO | JAILLON, OLIVIER
    Committee:
         PRESIDENT: GONZÁLEZ HERNÁNDEZ, JOSÉ MANUEL
         SECRETARI: GONZÁLEZ ACINAS, SILVIA
         VOCAL NO PRESENCIAL: DELMONT, TOM
    Thesis abstract: There is a myriad of microorganisms on Earth contributing to global biogeochemical cycles. In the surface ocean, the smallest microbes (picoplankton) are responsible for an important fraction of the total atmospheric carbon and nitrogen fixation. The ocean picoplankton encompasses both prokaryotes (bacteria and archaea) and tiny unicellular eukaryotes (protists). Despite their overall importance for the functioning of the biosphere, many questions remain unanswered on their biogeography, population dynamics, interactions, and evolution. Answering these questions is essential in the context of global change, as alterations of the ocean microbiome could impact the function of multiple ecosystems. In this thesis, we aim at reducing the knowledge gap on the above topics through the application of High-Throughput Sequencing (HTS) and genomic approaches, using data collected during the circumglobal Tara Oceans and Malaspina-2010 expeditions, as well as at the Gulf of Maine (North Atlantic), and two Northwestern Mediterranean coastal microbial observatories (BBMO and SOLA stations). Chapters 1 and 2 are dedicated to a small protistan group of heterotrophic flagellates (HF): the Marine Stramenopiles (MAST)-4, relevant during picoplankton grazing and nutrient remineralization. Due to its widespread distribution and relatively high abundance, MAST-4 has become a target group of microbes to study HF. Unfortunately, MAST-4 remains uncultured. We investigated four evolutionary-related species of MAST-4 (species A, B, C, and E) by reconstructing their genomes with Single-Cell genomics data. In chapter 1, co-occurrence and biogeographic analyses in the surface global ocean indicated contrasting patterns driven by temperature. Although MAST-4 species were similar in terms of broad metabolic functions, they differed in the set of genes related to the food degradation machinery. We proposed that differential niche adaptation to temperature and prey type has promoted the evolutionary diversification in MAST-4. In chapter 2, we explore the intraspecies genomic divergence within each MAST-4 in the surface global ocean using metagenomic data. We found highly-differentiated populations among MAST-4A and C but lowly-differentiated populations in species B and E. Nevertheless, positive selection in specific genes pointed to niche adaptation to different ocean basins driven by fluctuating temperature and salinity conditions.Environmental factors also oscillate over time, but the effect they have over population remains a mystery. In chapter 3, we compared the genomic differentiation of 495 abundant prokaryotic metagenome-assembled genomes (MAGs) over 12 and 7 years in BBMO and SOLA stations, and across the surface global ocean. Our results suggested a stronger population differentiation at large-spatial scales, modulated by temperature and salinity, compared to long-temporal scales. However, underlying population structure was still detected in both time-series, with differential patterns of positive selection within the same genes. Although protists and prokaryotes are very different in terms of cellular structure, feeding, diversity, and reproduction, they are interconnected through biogeochemical and food web networks. In chapter 4, we developed an approach to infer potential interactions between these two groups based on the annotation of functional genes within Single-Amplified Genomes (SAGs). From a collection of over 3,000 SAGs, we corroborated associations (potential interactions) reported in previous works and inferred new ones involving uncultured marine protists that may hold important roles in ecosystem functioning.This thesis not only contributes to a better understanding of the biogeography, population dynamics, interactions, and evolution of marine microorganisms, but it also constitutes an expandable resource to test future hypotheses involving the ocean microbiome.

DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING

  • MONTERDE GASCÓN, MARIA CARMEN: Nuevos interconectores pulvimetalúrgicos para sistemas de óxido sólido de alta temperatura: desarrollo, optimización y prototipado
    Author: MONTERDE GASCÓN, MARIA CARMEN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
    Department: (CEM)
    Mode: Confidentiality
    Deposit date: 13/12/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: JIMENEZ PIQUÉ, EMILIO | CALERO MARTINEZ, JOSÉ ANTONIO | TORRELL FARO, MARC
    Committee:
         PRESIDENT: GARCÍA CANO, IRENE
         SECRETARI: MORALES COMAS, MIGUEL
         VOCAL: ETXEBERRIA URANGA, JON JOSEBA
    Thesis abstract: The transition towards to low carbon energy generation is promoting the installation of renewable energy sources, their successful deployment requires efficient energy storage systems in order to meet demand. Hydrogen generation has emerged as a good alternative for energy storage. High-temperature solid oxide electrolyze (SOEC) systems are the most efficient systems for generating hydrogen from electrolysis of water. These SOEC systems exhibit 80% energy conversion rates in the operating temperature range of 700 - 900ºC.The manufacturing techniques of the components is one of the main drawbacks of SOEC systems, and both performance and durability are under investigation in order to increase their lifetime and market penetration in competition with other electrolysis technologies with lower efficiencies.Metal interconnects are a vital part of high-temperature solid oxide systems as they electrically connect the cells and distribute the flow of gases that feed the final stack. The commercialization of these systems can be boosted by improving the lifetime and lowering the cost of these systems, which is partly driven by the high cost of the interconnect. Research is currently being carried out on ferritic stainless steel (FSS) interconnects, which are cheaper than ceramic materials, but shaw degradation problems at the high working temperatures of 750-800 ºC. Corrosion phenomena and chromium evaporation negatively affect system performance dueto increased electrlcal resistance and oxygen electrode polsoning has been shown to be effective In mitigation. The effectiveness in mitlgating these effects has been preven by the application of chromium barrier coatings such as MnCo2O4. This thesis deals with the design, developrnent, manufacture and optirnizatlon of a flat coated FSS metal lnterconnect manufactured by conventional powder metallurgy. The functionality in a single repeat unit has been validated in a high temperature electrolyze apparatus designed and built also within this study. This thesis can be divided into three blocks: i)design and fabrication by conventional powder metallurgy of a functional FSS interconnector, ii) study of various application techniques of the MnCo2O4 barrier coating such as roll coating, an additive manufacturing technique such as ink jet printing on demand (DOD) and electrophore!lc deposition (EPD), iii) design, construction and validation of a first high temperature electrolyze at national level built and validated with a commercial stack and which has been working directly connected to an industrial station such as the Riu Sec in Spain and iiii) validation of the interconnect and barrier !ayer efficiency with a commercia/ ce// in SOEC mode in tlle e/ectro/yzer for 750h at BOO"C and in SOFC mode after 150h in an /REC measurement station.In summary, this thesis deals with the design, development, manufacture and optimization of a flat coated FSS metal interconnect manufactured by conventional powder metallurgy. The functionality in a single repeat unit has been validated in a high temperature electrolyze apparatus designed and built also within this study. The results obtained show a functional interconnect in high temperature solid oxide systems in both SOFC and SOEC rnodes fabricated by conventional powder metallurgy.The results obtained show a functional interconnect in high temperature solid oxide systems in both SOFC and SOEC modes fabricated by conventional powder metallurgy.Finally, this thesis details a journey through the different maturity levels of high temperature solid oxide technology particularly in SOEC mode. The study has started ata TRL 3 proof of concept of high temperature solid oxide technology and has reached TRL 7 where a high temperature electrolyzer apparatus has been fabricated, validated and connected toan industrial installation, and a flat coated FSS metal interconnector validated on electrolyzer equipment designed and built in this study.

DOCTORAL DEGREE IN OPTICAL ENGINEERING

  • MARTÍNEZ MARIN, POL: ESTUDI I DESENVOLUPAMENT DE SENSORS ÒPTICS ULTRA-RÀPIDS PER A METROLOGIA TRIDIMENSIONAL DE SUPERFÍCIES
    Author: MARTÍNEZ MARIN, POL
    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: 19/12/2022
    Reading date: 10/02/2023
    Reading time: 10:15
    Reading place: Auditori Joan Salvadó (Centre Universitari de la Visió. Passeig del Vint-i-dos de Juliol, 660, 08222 Terrassa)
    Thesis director: ARTIGAS PURSALS, ROGER | BERMUDEZ PORRAS, CARLOS
    Committee:
         PRESIDENT: ROYO ROYO, SANTIAGO
         SECRETARI: BOSCH PUIG, SALVADOR
         VOCAL: MICO SERRANO, VICENTE
    Thesis abstract: Three-dimensional measurement of roughness and shape of a surface provides information about an object properties through surface parameters. These parameters are defined by international standards and can describe the feature behaviour of its surface. The main benefit of using optical measurement techniques is that the sample under inspection does not suffer any damage when measured. With contact-based methods, otherwise, the damages can occur. With the evolution towards industry 4.0, there is a need to measure faster with smaller sensors, in order to have a manufacture-quality control close loop. This leads to the objective of this thesis, which is to develop two ultrafast sensors for 3d surface metrology. The first sensor consists in an evolution of an existing commercial system using conventional techniques. It has to be reduced in dimensions and cost-wise, while increasing its acquisition speed. The second sensor must use a single-shot technique, so that with one single image, the sample's surface's heights can be retrieved. Therefore, the current optical techniques for 3d surface metrology are reviewed. There are classified in three-main categories: classical techniques, single-shot techniques and scanning systems without moving parts. The development of the thesis is divided into two parts, corresponding to each sensor. In the first part, the opto-mechanical design of the sensor is developed, together with its corresponding analysis. One of the most relevant changes is the replacement of the microdisplay with a glass checkerboard pattern. The microdisplay is a critical component for measuring with confocal, so the algorithms have had to be adapted to obtain equivalent results. In addition, sinusoidal movement profiles have been studied to reduce the sensor's downtime and minimize motor wear. In the second part the objective is to demonstrate the feasibility of using CKM (Complementary Kernel Matching) for surface measurement. This technique is based on the image processing after a calibration that analyzes the Point Spread Function (PSF) through the optical axis. In order to demonstrate it, a prototype based on two cameras has been developed, a new calibration method has been designed, which divides the image into smaller regions using a matrix of pinholes. A new algorithm has also been developed to detect the height of the sample from the axial response obtained. Finally, a real sample has been measured with satisfactory results.
  • PEÑA GUTIERREZ, SARA: Development of a snapshot full-stokes polarimetric camera: Application to image in diffusive media
    Author: PEÑA GUTIERREZ, SARA
    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: 13/12/2022
    Reading date: 24/02/2023
    Reading time: 10:30
    Reading place: Auditori Joan Salvadó del Centre Universitari de la Visió. (Passeig del Vint-i-dos de Juliol, 660, 08222 Terrassa)
    Thesis director: ROYO ROYO, SANTIAGO
    Committee:
         PRESIDENT: CAMPOS COLOMA, JUAN
         SECRETARI: VILASECA RICART, MERITXELL
         VOCAL: GARCÍA CAUREL, ENRIQUE
    Thesis abstract: Polarization is one of the properties of light and it is often put aside. Human beings receive light beams and process only the intensity and wavelength information. Our optical system lacks the capability of ¿seeing¿ polarization in comparison to other animals. The vectorial nature of polarization is uncorrelated to the intensity and colour information and this can unveil additional information for improving the current technology.This Thesis aims to develop a camera capable of measuring the full polarization in a 2D scene. In particular, it focuses on the design and construction of a prototype that measures in the visible waveband the full-Stokes vector in a snapshot such that the acquisition time and noise equalization are balanced while reducing movement and registration artefacts.The Thesis starts with the revision of the current state of the art in the polarimetric imaging field. Based on this, the optomechanical design of the polarimetric camera is developed ensuring a faster acquisition of polarization since it integrates optimum states to immunize the system from Gaussian and Poisson noise.Accordingly, this Thesis proposes a general calibration methodology addressed to the radiometry of the sensor, the geometrical aberrations from optics and the polarization elements in the system to transform the intensity measurements into polarization information. Besides, this Thesis studies two imaging modes of polarization, Stokes imaging and Mueller matrix imaging, for different applications. The novelty of this system consists of the use of optimal polarization states in a division of aperture architecture for noise immunization.Finally, this Thesis studies the application of the system to improve detection in the real-world problem of seeing through the fog. Polarization information can improve the range of detection due to the polarization memory effect. This system could be employed inside a multimodal system to ensure detection when others are hampered due to external conditions.

DOCTORAL DEGREE IN PHOTONICS

  • WANG, YONGJIE: Eco-Friendly Solar Cells with Cation-Engineered AgBiS2 Nanocrystals
    Author: WANG, YONGJIE
    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: 11/01/2023
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: KONSTANTATOS, GERASIMOS
    Committee:
         PRESIDENT: VAYNZOF, YANA
         SECRETARI: SAUCEDO SILVA, EDGARDO
         VOCAL: HOYE, ROBERT LIANQI ZHAO
    Thesis abstract: Climate change and global energy demand urge the development of renewable energy sources for worldwide power supply. Photovoltaic devices that convert solar energy directly into electricity are the most promising, if not the only, technique to meet the requirements. Solution-processed solar cells are especially attractive due to their lightweight, low cost, and large-area mass manufacturing features. Among solution-processed materials, nanocrystals are one of the most promising, thanks to their material-property tunabilities, such as size, morphology, composition, electronic and optical properties, just to name a few. In the last decade, nanocrystal solar cells are mainly based on lead chalcogenide nanocrystals, although they face problems related to the toxicity of the element lead. Silver-bismuth sulfide nanocrystals are excellent substitutes for lead chalcogenides, thanks to their adequate bandgaps and extraordinarily high absorption coefficients. However, the energy conversion efficiency has lagged behind their toxic counterparts, mainly due to limited charge-carrier diffusion length and uncontrolled cation-disorder.In this thesis, we pinpoint the detrimental effects of cation inhomogeneity in ternary silver bismuth sulfide nanocrystals and further homogenize the cation-disorder by a facile post-annealing process, leading to absorption coefficients higher than any other commonly used solar materials over a wide range of 400 - 1000 nm. The cation-disorder configuration transition was further confirmed by the combination of ab initio density functional theory calculation and experimental material characterizations. Further optical modelling suggested a 30nm absorber layer possesses the potential for high Jsc up to 30 mA/cm2 and efficiency up to 26%. In addition to optical absorption enhancements, we also found elongated diffusion length up annealing, pointing to an anticipated high performance with ultrathin absorber. Ultrathin solar cells were thus fabricated with specially designed architecture and we achieved a record efficiency up to 9.17%, independently certified as 8.85% by Newport. The ultrathin solar cells also showed excellent stability under ambient conditions.In order to comply with mass manufacturing processes, we developed a solution-phase ligand-exchange procedure based on aqueous nanocrystal inks that enable single-step deposition of the active layer, reducing drastically the number of processing steps. Solar cell devices were built with the nanocrystal inks based on single-step deposition process and they showed a promising efficiency up to 7.3%, much higher than previous ink device record. In sum, we have achieved record-high performance, exceptionally stable AgBiS2 nanocrystal solar cells with both solid-state and solution-phase ligand-exchange procedures. This work sets a landmark for the development of environmentally friendly, low-temperature, solution-processed inorganic solar cells and opens a new field of engineering the atomic configuration of semiconductors as a means to achieve extraordinary optoelectronic properties.

DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS

  • GONZÁLEZ RODRÍGUEZ, MARTA: Nonlinear modeling and characterization of SAW devices for communications systems
    Author: GONZÁLEZ RODRÍGUEZ, MARTA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS
    Department: Department of Signal Theory and Communications (TSC)
    Mode: Confidentiality
    Deposit date: 11/01/2023
    Reading date: 10/02/2023
    Reading time: 11:00
    Reading place: Edifici C4-028-2, EETAC, Esteve Terradas, 7, Campus UPC, 08860.-Castelldefels (Barcelona)
    Thesis director: COLLADO GOMEZ, JUAN CARLOS | GONZALEZ ARBESU, JOSE MARIA
    Committee:
         PRESIDENT: AIGNER, ROBERT
         SECRETARI: GELONCH BOSCH, ANTONIO JOSE
         VOCAL: OLIVARES ROZA, JIMENA
    Thesis abstract: Nowadays, worldwide booming growth in mobile devices puts a lot of pressure on the mobile communications technologies since an enormous amount of requirements, mainly focused on delivering enhanced mobile broadband services to consumers, are needed. The ever-increasing data rate requirements and the support for wireless technologies, like 5th Generation (5G), set a lot of pressure to manufacturers in finding new solutions to face the coexistence and integration of several radio systems operating in the Radio-Frequency (RF) modules.This scenario introduces a variety of challenges that have to be faced when using multi-band operation. One of them is to fight against the desensitization in the RF front-end due to the generation of spurious signals by the nonlinearity of passive components inside the handset. Passive InterModulation (PIM) is becoming a major concern in the design of RF transceivers where the transmitter and receiver share the antenna, since it can cause receiver blocking. PIM might arise from different components such as antennas, mixers, filters, etc. Among the components into the RF chain, the filtering stage is one of the critical components since apart from high selectivity and miniaturization, they also have to meet low PIM specifications and thus, becoming a challenging taskfor RF designers.To face these technological constraints, acoustic wave filters have been giving response to this need because of their outstanding performance, and have become a suitable solution for the emerging communications standards. Bulk Acoustic Wave (BAW) and Surface Acoustic Wave (SAW) are nowadays the main technologies, offering filtering structures with very low insertion losses andgood out-of-band rejection that are in compliance with current system specifications. Despite it seems clear that the acoustic technology shows major advantages, there are some drawbacks too. One of them is that both BAW and SAW resonators exhibit a nonlinear behavior giving place to Intermodulation (IMD) and Harmonic distortion (H). Accordingly, RF front-end high linearization demands may become an issue to be solved in the definition of new advanced services in future standards.There has been a rise in interest in the modeling and simulation of the nonlinearities of SAW devices during the last two decades. Despite different approaches Finite Element Model (FEM), Coupling of Modes (COM) and P-Matrix had been widely used, there is a lack of consensus about the nonlinear generation driven by the difficulty to identify geometry-independent material parameters that could predict the nonlinear behavior of any resonator before manufacturing.To this end, the thesis will be focused on the accurate nonlinear characterization of SAW devices. The modeling and simulation ofnonlinearities on SAW resonators will be the most important milestone of the thesis. Specifically, the development of fundamental circuit models to account for the nonlinear mechanism occurring in SAW resonators and, the implementation of mathematical techniques to synthesize circuital networks based on these models to reduce the computational time to improve the simulation andmodeling of these resonators.The novelty of this thesis lies in the development of a characterization process for SAW resonators allowing to predict the behavior of new devices with other geometries. To be successful in this process, an equivalent nonlinear circuital model is proposed. The developed model is distributed and directly related to the the local constitutive equations of the piezoelectricity. Special efforts areexpended towards developing a new method of analysis for the simulation of both H and IMD generation in SAW resonators and filters. Several experimental verifications have shown that despite of its simplicity, the proposed model is extremely consistent and fast to simulate the linear and nonlinear response of different devices using only a geometry-independent nonlinear parameter.
  • MOSELLA MONTORO, ALBERT: Graph convolutional neural networks for 3D data analysis
    Author: MOSELLA MONTORO, ALBERT
    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: 13/01/2023
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: RUIZ HIDALGO, JAVIER
    Committee:
         PRESIDENT: SMOLIC, ALJOSA
         SECRETARI: MARQUES ACOSTA, FERNANDO
         VOCAL: HARO ORTEGA, GLORIA
    Thesis abstract: Deep Learning allows the extraction of complex features directly from raw input data, eliminating the need for hand-crafted features from the classical Machine Learning pipeline. This new paradigm brought a boost in the performance across several domains, including computer vision, natural language processing and audio processing. However, there are still challenges when dealing with unorganized structures. This thesis addresses this challenge using Graph Convolutional Neural Networks, a new set of techniques capable of managing graph structures that can be used for processing 3D data. The first part of the thesis focuses on the Graph Analysis task, in which we will study the capabilities of Graph Convolutional Neural Networks to capture the intrinsic geometric information of 3D data. We propose the Attention Graph Convolution layer that learns to infer the kernel used during the convolution, taking into account the particularities of each neighbourhood of the graph. We explore two variants of the Attention Graph Convolution layer, one that explores a residual approach and another one that allows the convolution to combine different neighbourhood domains. Furthermore, we propose a set of 3D pooling layers that mimics the behaviour of the pooling layers found in common 2D Convolutional Neural Networks architectures. Finally, we present a 2D-3D Fusion block capable of merging the 3D geometric information that we get from a Graph Convolutional Neural Network with the texture information obtained by a 2D Convolutional Neural Network. We evaluate the presented contributions on the RGB-D Scene Classification task. The second part of this thesis focuses on the Node Analysis task, which consists of extracting features on a node level, taking into account the neighbourhood structure. We present the Multi-Aggregator Graph Convolution layer that uses a multiple aggregator approach to better generalize for unseen topologies and learn better local representations. In addition, it reduces the memory footprint with respect to the Attention Graph Convolution layer. Finally, we analyze the capabilities of our proposed Graph Convolution layers to deal with heterogeneous graphs where the nodes of the graph may belong to different modalities. We evaluate the presented contributions with the Computer Graphics process of skinning a character mesh. Specifically, we propose a Two-Stream Graph Neural Network capable of predicting the skinning weights of a 3D character.

DOCTORAL DEGREE IN TEXTILE AND PAPER ENGINEERING

  • GÜNTHER, KAROLINE: Analysis of the influence of false twist integrated into a high speed drafting system of an air jet spinning machine
    Author: GÜNTHER, KAROLINE
    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 Textile and Paper Engineering (ETP)
    Mode: Normal
    Deposit date: 27/09/2022
    Reading date: 24/02/2023
    Reading time: 11:00
    Reading place: Sla d'actes de l'INTEXTER
    Thesis director: TORNERO GARCÍA, JOSÉ ANTONIO | WEIDE, THOMAS
    Committee:
         PRESIDENT: DIAZ GARCIA, PABLO
         SECRETARI: CANO CASAS, FRANCESC
         VOCAL: TZVETKOVA, MILENA DIMTCHOVA
    Thesis abstract: Air jet spinning is an emerging technology, already well established in the textile market. The commercial success increased over the last decades and intensified the research and innovation approach in the field of air jet spinning machines. The requirements for establishing air spun yarn in the textile market include high yarn quality, high production speeds and high material yield during the process.The concept and the quality of the integrated drafting system of an air jet spinning machine is one of the responsible parts to influence the named requirements. Moreover, the drafting system directly influences the regularity of fibre motion during the transportation to the spinning nozzle. In this case, the fibres need to deal with challenges like highly increasing velocities of the roller pairs and resulting air turbulences which cause misaligned fibres at the main draft zone.False twist is a welt-known principle in the textile process technology. False twist is used to stabilize the spinning stability, to create special effects on yarn structure or to impact the spinning process in general.Based on the principles of false twist, the aim of this work is to use the characteristics of false twist in the drafting system of an air jet spinning machine to improve the fibre motion during drafting. The PhD thesis presents the use of the principles of false twist implementation into the drafting system to influence the fibre control during high speed drafting for air jet spinning machines.Therefore, two prototypes were developed, tested, and evaluated by their impact for the fibre motion through the drafting system. A dynamic false twist device which can insert false twist individually set by torque and velocity into the drafted fibre bundle is used. Moreover, a video analysis tool was developed to measure the fibre motion. In the theoretical part, a control analysis of false twist integration into a fibre assembly was developed, which simplified the prediction of fibre movements. The theoretical analyses led to a better knowledge of the fibre movement within a high speed drafting system with high velocities.

Last update: 28/01/2023 05:45:10.