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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 AEROSPACE SCIENCE AND TECHNOLOGY

  • CAAMAÑO ALBUERNE, MARÍA: Network-based ionospheric gradient monitoring to support ground based augmentation systems
    Author: CAAMAÑO ALBUERNE, MARÍA
    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: 22/04/2022
    Reading date: 12/07/2022
    Reading time: 11:00
    Reading place: FME- Mòdul C3, Sala 204 (Biblioteca Dept. Matemàtiques), Campus Barcelona Nord UPC.
    Thesis director: SANZ SUBIRANA, JAIME | JUAN ZORNOZA, JOSE MIGUEL
    Committee:
         PRESIDENT: PULLEN, SAMUEL PHILLIP
         SECRETARI: ROVIRA GARCIA, ADRIÀ
         VOCAL: SOKOLOVA, NADEZDA
    Thesis abstract: The Ground Based Augmentation System (GBAS) is a local-area, airport-based augmentation of Global Navigation SatelliteSystems (GNSSs) that provides precision approach guidance for aircraft. It enhances GNSS performance in terms of integrity,continuity, accuracy, and availability by providing differential corrections and integrity information to aircraft users. Differentialcorrections enable the aircraft to correct spatially correlated errors, improving its position estimation. Integrity parameters enable it to bound the residual position errors, ensuring safety of the operation. Additionally, a GBAS ground station continuously monitors and excludes the satellites affected by any system failure to guarantee the system integrity and safety.Among the error sources of GNSS positioning, the ionosphere is the largest and most unpredictable. Under abnormalionospheric conditions, large ionospheric gradients may produce a significant difference between the ionospheric delayobserved by the GBAS reference station and the aircraft on approach. Such a spatially decorrelated ionosphere could lead tohazardous unbounded position errors if undetected. Conventional GBAS solutions to mitigate this threat assume that the ¿worstcase" ionospheric gradient ever observed in the relevant region is always present, which is a very conservative assumption. This approach, which relies on the conservative ionospheric threat models derived for GBAS, maximizes integrity, often at the expense of availability and continuity, especially in geographic areas with highly active ionosphere.As opposed to assuming a permanent ¿worst-case¿ gradient, I propose the Network GBAS concept, in which several reference stations collaborate to monitor for actual ionospheric gradients. This concept consists of two main steps. First, the network detects the anomalous ionospheric gradients, estimates the gradient parameters, and transmits this information to the GBAS stations installed in its coverage area. Then, the GBAS stations replace the ¿worst-case¿ gradient used to mitigate the ionospheric threat in current algorithms with the gradient information provided by the network. This approach reducesconservatism and leads to an improvement of the system availability without compromising user integrity.This thesis validated the performance of the detection and estimation algorithms with simulated and real ionospheric gradients from two different locations known for their high levels of ionospheric activity. One location was Alaska, where the analyzed real anomalous gradients were small in size but fast-moving; the other location was Brazil, dominated by large-but-slow anomalous gradients. This analysis led to the adaptation of the algorithms to work in challenging scenarios.The evaluation of the Network-GBAS concept compared in simulations the availability of a Category I (CAT I) GBAS station atthe Brazil location in two cases: assuming the conservative ionospheric threat model, and using the gradient informationprovided by the network. On a selected nominal day (i.e., with no significant ionospheric activity), availability improved from79.5% to 94.6% during the nighttime. On a selected active day, availability improved from 68.7% to 89.5% during the nighttime. During daytime, availability achieved 100% on both days.Results demonstrate that the Network-GBAS concept can significantly enhance CAT I GBAS availability in active ionosphericregions without compromising user integrity. Furthermore, by incorporating the information provided by the network into existing solutions, the Network-GBAS is compatible with existing algorithms and hardware, and thus should be certifiable if adapted to the characteristics of each region where GBAS is fielded.
  • COMA COMPANY, MARTÍ: Optimization on industrial problems focussing on multi-player strategies
    Author: COMA COMPANY, MARTÍ
    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: 30/05/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: BUGEDA CASTELLTORT, GABRIEL | PONS PRATS, JORDI
    Committee:
         PRESIDENT: VALERO, EUSEBIO
         SECRETARI: PRATS MENENDEZ, XAVIER
         VOCAL: GREINER SÁNCHEZ, DAVID
    Thesis abstract: Algorithms (EA) are useful optimization methods for exploration of the search space, but they usually have slowness problems to exploit and converge to the minimum with accuracy. On the other hand, gradient based methods converge faster to local minimums, although are not so robust (e.g., flat areas and discontinuities can cause problems) and they lack exploration capabilities. This thesis presents and analyze four versions of a hybrid optimization method trying to combine the virtues of Evolutionary Algorithms (EA) and gradient based algorithms, and to overcome their corresponding drawbacks. The proposed Hybrid Methods enables working with N optimization algorithms (called players), multiple objective functions and design variables, and define them differently for each player. The performance of the Hybrid Methods are compared against a gradient based method, two Genetic Algorithms (GA) and a Particle Swarm Optimization (PSO). Tests have been conducted with mathematical benchmark problems (synthetic tests designed to specifically test optimization methods) and an engineering application with high demanding computational resources, a Synthetic Jet actuator for Active Flow Control (AFC) over a 2D Selig-Donovan 7003 (SD7003) airfoil at Reynolds number 6 x 10^4 and a 14 degree angle of attack. The Active Flow control problem has been used in a single optimization problem and in a two objective optimization problem

DOCTORAL DEGREE IN ARCHITECTURAL, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY

  • ZOLFAGHARI, SEYYED MOHAMMADREZA: Sustainability Assessment Model of Mass Housing's Interior Rehabilitation. Economic, environmental, and social impacts of interior rehabilitation scenarios in Iranian MHs. The case of Ekbatan, Tehran, Iran
    Author: ZOLFAGHARI, SEYYED MOHAMMADREZA
    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: 08/06/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: PONS VALLADARES, ORIOL | NIKOLIC, JELENA
    Committee:
         PRESIDENT: SIMÓ I SOLSONA, MONTSERRAT
         SECRETARI: CORNADÓ BARDÓN, CÒSSIMA
         VOCAL: HOSSEINI, SEYED MOHAMMAD AMIN
    Thesis abstract: The construction of mass housings (MHs) solved high demands for housing in urban areas in the 1960s and 1970s worldwide. After decades of continuous use and inadequate maintenance, these MHs have been censured due to their several social, economic, and environmental negative impacts. The mentioned MH¿s deficiencies require MH interior rehabilitation. In Iran, this rehabilitation is currently based mainly on traditional and conventional construction technologies and techniques, most of which neither follow sustainability requirements nor contemporary building standards. In this regard, selection of proper MHs¿ interior rehabilitation procedures, from a sustainability point of view, is a crucial issue that faces several challenges since this is a multidisciplinary and multi-criteria process. To overcome this challenge, several studies applied different building sustainability assessment (BSA) methods and tools. Most BSAs have various shortfalls such as (i) lacking a holistic approach, (ii) neglecting the involved stakeholders¿ satisfaction, and (iii) employing some predefined sustainability indicators some of which are not relevant or applicable for all projects. These BSA¿s shortfalls lead numerous researchers to develop individual models based on MCDM methods to fulfill their projects¿ objectives. The present thesis aims to develop a novel MCDM model based on the MIVES and Delphi methods for holistic sustainability assessment of interior rehabilitation of MHs. This MIVES-Delphi model relies on a comprehensive literature review, seminars composed by experts, on-site surveying, LCA, BIM, user- and expert-based questionnaires, bias reduction, and sensitivity analysis. The model was first applied to the Ekbatan MH case study, which is the largest MH in Iran. Moreover, the author has applied this novel model to assess the sustainability of four different interior rehabilitation scenarios, including three common rehabilitation scenarios plus an innovative one. Consequently, the new model has been validated and the most sustainable rehabilitation scenario has been selected. This validation proves that the developed model can objectively quantify the holistic sustainability assessment of interior rehabilitation in MHs in Iran by considering the involved stakeholders¿ preferences. Additionally, this model has flexibility, adaptability, and applicability for any type of interior rehabilitation procedure in MHs in different geographical contexts as well as different construction phases including design, construction, and rehabilitation. The specific results regarding the rehabilitation scenarios¿ evaluation disclosed that none of the studied three common conventional rehabilitation scenarios could either meet the minimum sustainability target value or serve as proper solutions for interior rehabilitation. On the other hand, the fourth scenario, with a global sustainability index of 0.71, could meet the standard minimum target. This proves a possibility for innovative rehabilitation processes to have positive effects on increasing the sustainability performance in MH buildings. This thesis aims to contribute to moving forward to more sustainable rehabilitation techniques for interior rehabilitation in MHs as well as moving towards more sustainable architecture and construction. Moreover, this thesis opens up opportunities for future research perspectives that could be (i) adaptation and implementation of the developed model to other MHs beyond Tehran in order to consolidate and strengthen the proposed model, and (ii) combination of the developed model with Fuzzy logic to reach a superior methodology. Keywords: MHs¿ interior rehabilitation, Common rehabilitation techniques, Advanced rehabilitation techniques, Sustainability assessment, MIVES, Delphi.

DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION

  • CHACÓN ENCALADA, LUIS ALEJANDRO: A socio-technical approach for assistants in human-robot collaboration in industry 4.0
    Author: CHACÓN ENCALADA, LUIS ALEJANDRO
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION
    Department: Department of Automatic Control (ESAII)
    Mode: Normal
    Deposit date: 11/05/2022
    Reading date: 08/07/2022
    Reading time: 11:00
    Reading place: ETSEIB - Aula Capella, Escola Tècnica Superior d'Enginyeria Industrial de Barcelona (ETSEIB), Av. Diagonal, 647, 08028 Barcelona
    Thesis director: ANGULO BAHON, CECILIO | PONSA ASENSIO, PEDRO
    Committee:
         PRESIDENT: RODRÍGUEZ SEDANO, FRANCISCO
         SECRETARI: GARRELL ZULUETA, ANAÍS
         VOCAL: GRANOLLERS SALTIVERI, ANTONI
    Thesis abstract: The introduction of technologies disruptive of Industry 4.0 in the workplace integrated through human cyber-physical systems causes operators to face new challenges. These are reflected in the increased demands presented in theoperator's capabilities physical, sensory, and cognitive demands. In this research, cognitive demands are the most interesting. In this perspective, assistants are presented as a possible solution, not as a tool but as a set of functions that amplify human capabilities, such as exoskeletons, collaborative robots for physical capabilities, virtual and augmented reality for sensory capabilities. Perhaps chatbots and softbots for cognitive capabilities, then the need arises to ask ourselves: How can operator assistance systems 4.0 be developed in the context of industrial manufacturing? In which capacities does the operator need more assistance?From the current paradigm of systematization, different approaches are used within the context of the workspace in industry 4.0. Thus, the functional resonance analysis method (FRAM) is used to model the workspace from thesociotechnical system approach, where the relationships between the components are the most important among the functions to be developed by the human-robot team. With the use of simulators for both robots and robotic systems, the behavior of the variability of the human-robot team is analyzed. Furthermore, from the perspective of cognitive systems engineering, the workspace can be studied as a joint cognitive system, where cognition is understood as distributed, in a symbiotic relationship between the human and technological agents.The implementation of a case study as a human-robot collaborative workspace allows evaluating the performance of the human-robot team, the impact on the operator's cognitive abilities, and the level of collaboration achieved in the human-robot team through a set of metrics and proven methods in other areas, such as cognitive systems engineering, human-machine interaction, and ergonomics. We conclude by discussing the findings and outlook regarding future research questions and possible developments.

DOCTORAL DEGREE IN BIOMEDICAL ENGINEERING

  • CASTILLO ESCARIO, YOLANDA: Biomedical signal interpretation and smartphone sensors for the assessment of trunk function and sleep disorders in patients with spinal cord injury
    Author: CASTILLO ESCARIO, YOLANDA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN BIOMEDICAL ENGINEERING
    Department: Department of Automatic Control (ESAII)
    Mode: Article-based thesis
    Deposit date: 30/05/2022
    Reading date: 27/06/2022
    Reading time: 10:00
    Reading place: Sala Actes de l'Escola d'Enginyeria Barcelona Est (EEBE), Campus Diagonal Besòs, Av. d'Eduard Maristany, 16, 08019 Barcelona
    Thesis director: JANE CAMPOS, RAIMON
    Committee:
         PRESIDENT: REILLY, RICHARD
         SECRETARI: VALLVERDU FERRER, MARIA MONTSERRAT
         VOCAL: CARRAULT, GUY
    Thesis abstract: Spinal cord injury (SCI) is one of the leading causes of disability worldwide. SCI causes motor and sensory impairment but is also associated with many other health problems. Two of these problems are trunk muscle impairment and sleep disorders. Impaired trunk function affects postural control and sitting balance, which are critical for activities of daily living. Disturbed sleep causes fatigue and sleepiness and can lead to serious comorbidities, impacting patient recovery and outcomes. However, due to the multiple health problems secondary to SCI and the limitations in current diagnostic tools, trunk function and sleep are rarely examined after SCI. The non-invasive acquisition and analysis of biomedical signals can help to overcome this issue, providing quantitative measures to assess patient condition. Smartphones can facilitate this task, thanks to their ubiquitous presence and powerful sensors.The aim of this PhD thesis is to propose new smartphone-based tools and biomedical signal analysis techniques for the quantitative assessment of trunk function and sleep-disordered breathing (SDB) in patients with SCI. This dissertation is divided into two parts, including four publications in high-impact journals. The first part addresses the characterization of trunk function in healthy subjects and patients with cervical (cSCI) and thoracic SCI (tSCI). The second part focuses on the development of a mobile health (mHealth) system based on smartphone audio signals for obstructive sleep apnea (OSA) diagnosis, and the detection and monitoring of SDB in SCI patients.The first part of the thesis introduces a novel methodology to quantitatively evaluate trunk function by combining electromyography (EMG) and smartphone accelerometry. In the first study, we characterized the muscle activity and movement patterns of trunk flexion during reaching in healthy humans and investigated if trunk stability was affected by a startling acoustic stimulus (SAS). We found that SAS markedly reduced the response time (RespT) and EMG onset latencies of all muscles (the so-called StartReact effect), either prime movers or stabilizers. In the second study, we evaluated trunk function and the effects of a SAS in patients with cSCI and tSCI. The results revealed deficits in postural control and compensatory strategies employed by SCI patients, such as delayed responses and high lateral deviations, with potential consequences for rehabilitation. This was the first study investigating the StartReact responses in trunk muscles in SCI. The SAS significantly shortened the RespT in tSCI, but not in cSCI, which suggests an increased cortical control in cSCI.In the second part of the thesis, we present mHealth tools for monitoring sleep disorders and investigate the sleep patterns of SCI patients. In the first article of this part, we designed a smartphone system and novel algorithms based on acoustic analysis for OSA screening. This approach demonstrated good agreement with a commercial system for home OSA diagnosis, correctly detecting and stratifying all the OSA patients. In the last article, sleep studies were performed in SCI patients using the smartphone, showing a very high prevalence of moderate-to-severe SDB in SCI patients. This study highlighted the problem of SDB in SCI and provided simple cost-effective tools to improve the detection and management of SDB in SCI patients.Overall, this thesis supports the use of smartphones and biomedical signal analysis for the assessment of trunk function and SDB in SCI patients. These novel approaches provide quantitative and objective measures for the evaluation and follow-up of patients in a simple and non-invasive way. We also give insights into the underlying mechanisms of postural control, respiratory function during sleep, and the changes occurring after SCI. Consequently, our results open the way for improving the management of health complications associated with SCI or other disabling conditions.

DOCTORAL DEGREE IN CHEMICAL PROCESS ENGINEERING

  • ECHEVARRÍA DÍEZ-CANEDO, CARLOS: Integration of advanced wastewater treatment and reclamation technologies for organic micropollutants removal and promote water reuse
    Author: ECHEVARRÍA DÍEZ-CANEDO, 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 CHEMICAL PROCESS ENGINEERING
    Department: Department of Chemical Engineering (EQ)
    Mode: Article-based thesis
    Deposit date: 28/04/2022
    Reading date: 14/07/2022
    Reading time: 11:00
    Reading place: EEBE- Sala Polivalent de l'Edifici I, planta baixa, Campus Diagonal-Besòs
    Thesis director: CORTINA PALLAS, JOSE LUIS | VALDERRAMA ANGEL, CESAR ALBERTO
    Committee:
         PRESIDENT: SASTRE REQUENA, ANA MARIA
         SECRETARI: IBAÑEZ MENDIZABAL, RAQUEL
         VOCAL: TEIXIDO PLANES, MARC
    Thesis abstract: Climate change and overpopulation are responsible for more frequent droughts, and the imbalance in the water resources management leads to a greater competition in the exploitation of freshwater sources. The introduction of alternative water resources such as reclaimed water seems to be one of the most sustainable option from an economic and environmental point of view, compared with other alternatives such as seawater desalination or water transfer. Nevertheless, the wide implementation of water reuse is still far from its whole potential and faces different local barriers related to public awareness and governance.The presence of organic micropollutants (OMP) in the water cycle, specifically in the wastewater effluents intended to be reclaimed and reused, has generated concern in public authorities due to their uncertain effects in human health. During last decades, limited removal efficiencies in conventional wastewater and reclamation schemes were reported by several authors. In this line, innovation must bring suitable solutions to unblock current barriers. Novel advanced water reclamation technologies need to be demonstrated to guarantee the cost-effective removal of OMP, as well as provide solutions in terms of brine management or valorization. Moreover, it is necessary to propose educational and communication initiatives and address innovative governance models to achieve the economic feasibility of water reuse projects. Throughout three published articles (Chapter 3-5), this PhD thesis evaluates and compares from a technical and economic point of view different advanced municipal wastewater reclamation schemes to produce cost-effective reclaimed water to be reused. An industrial pilot-scale demonstration conducted in El Baix Llobregat WRP (Barcelona, Spain), removal efficiencies and costs of different advanced reclamation technologies focused on the removal of OMP were assessed, including PAC-MBR, ozonation-UV, PAC-UF, UF-RO and an innovative high-performance sorbent (CNM). On the other hand, tools to ease decision making in water reuse planning through a rapid estimation in costs need to be proposed. Cost curves for CAPEX and OPEX for different reclamation technologies will be also calculated and applied to estimate implementation costs of reusing urban reclaimed water for industrial uses in three different case studies in the Barcelona (Spain) area.The ultimate goal is to provide knowledge to overcome some of the identified barriers and contribute to a higher implementation of water reuse.

DOCTORAL DEGREE IN CIVIL ENGINEERING

  • NASIKA, CHRISTINA: Model Order Reduction methods for sensor data assimilation to support the monitoring of embankment dams
    Author: NASIKA, CHRISTINA
    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: Change of supervisor
    Deposit date: 02/06/2022
    Reading date: 28/07/2022
    Reading time: 17:00
    Reading place: ETSECPPB, Sala C1-002 Campus Nord Barcelona, enllaç per videconferència estat alarma Covid: https://meet.google.com/myf-qkgs-rza
    Thesis director: DIEZ MEJIA, PEDRO | MASSART, THIERRY JAQUES | ZLOTNIK MARTINEZ, SERGIO
    Committee:
         PRESIDENT: SEVILLA CÁRDENAS, RUBÉN
         SECRETARI: RODRIGUEZ FERRAN, ANTONIO
         VOCAL NO PRESENCIAL: VEROY-GREP, KAREN
    Thesis abstract: The latest monitoring and asset management technologies for large infrastructures involve digital representations that integrate information and physical models, exist in parallel to the real-life structures, and are continuously updated based on assimilated sensor data, in order to accurately represent the actual conditions in the structures. This type of technology is often referred to as Digital Twin. The implementation of such cutting-edge technology in monitoring assets like tailings dams, or embankment dams in general, and other large structures, implies the development of highly efficient numerical tools that, combined with sensor data, may support rapid, informed decision making.For the particular case of embankment dams, enabling this type of technology requires an efficient numerical model that describes the coupled hydro-mechanical phenomena, pertinent to a dam functioning and safety. This may for instance be a Finite Elements (FE) model, describing the groundwater flow through unsaturated porous geomaterials. The process of updating and calibrating a model, such as the above mentioned FE model, based on sensor data is typically referred to as data assimilation. Often, this is achieved via an optimization approach, where a specific problem is solved multiple times for various parametric values, in search for the values that best describe the sensor data. The bottleneck in this type of application is typically the cost of multiple evaluations of the model, that may become prohibitive when the underlying FE model is large. In order to enable such applications, the present work proposes Model Order Reduction (MOR) methods tailored to the hydro-mechanical nonlinear problem at hand. MOR aims at the creation of a surrogate model that seeks an approximation of the FE solution in a reduced-order space. This is achieved by applying an offline-online strategy. In the offline stage, the solution manifold of the full-order problem is sampled, in order to identify a low-order affine subspace, where an accurate approximation of the full-order solution can be captured. To tackle the nonlinearities related to partially saturated conditions in the soil, a similar strategy must be employed in order to define reduced-order spaces where an affine system approximation may be recovered. The resulting Reduced Order Model (ROM) may be used as an efficient surrogate to the FE model in any problem that requires fast and/or repetitive solutions. In this work, MOR techniques are implemented to solve the coupled nonlinear transient problem under consideration. ROMs are created to solve problems that pertain to tailings dams and embankment dams monitoring. The efficiency and the accuracy of these models are demonstrated by solving inverse problems for parametric identification. MOR is found to be a reliable tool, significantly accelerating the inverse identification process while resulting to accurate solutions.

DOCTORAL DEGREE IN COMPUTATIONAL AND APPLIED PHYSICS

  • DE SWART, RINSE LEENDERT: Development and interactions of surfzone morphological patterns
    Author: DE SWART, RINSE LEENDERT
    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 COMPUTATIONAL AND APPLIED PHYSICS
    Department: Department of Physics (FIS)
    Mode: Normal
    Deposit date: 25/05/2022
    Reading date: 19/07/2022
    Reading time: 10:30
    Reading place: fib- Sala de actos de la Facultad de Informática de Barcelona (FIB), Edificio B6, Campus Barcelona Nord. URL videoconferencia: meet.google.com/xgz-nhrk-izz
    Thesis director: RIBAS PRATS, FRANCESCA | CALVETE MANRIQUE, DANIEL
    Committee:
         PRESIDENT: FALQUES SERRA, ALBERTO
         SECRETARI: FERNÁNDEZ MORA, MARIA DE LOS ANGELES
         VOCAL: CASTELLE, BRUNO
    Thesis abstract: A variety of morphodynamic patterns are typically present in the nearshore zone of sandy beaches that develop due to the interactions between waves, currents and the morphology. The most common are one or several nearshore sandbars that vary in configuration from shore-parallel to crescentic, the latter consisting of alongshore-rhythmic (i.e., undulating) bars (also called rip-channel systems). Crescentic bars are often coupled to similar undulations in the shoreline called megacusps. Understanding the evolution of nearshore sandbars and their coupling to the shoreline is important as they significantly affect the nearshore morphology and hydrodynamics. Alongshore sandbar variability has been studied extensively, but mostly at beaches with substantial tidal range and medium-high energetic waves. Furthermore, the dynamics of megacusps and their coupling with crescentic bars are much less understood.This thesis uses nearly 8 years of hourly time-exposure video images to study the development and interactions of crescentic bars and megacusps at the open, low-energetic, tideless beach of Castelldefels (northwestern Mediterranean Sea, Spain). This requires accurate directional wave conditions at shallow water which can be obtained in various ways. Here, the accuracy of two available large-scale wave models and propagating measured wave conditions (integrated wave parameters and 2D frequency-direction spectra) using wave ray theory or the SWAN wave model was assessed. Comparing the results of the different methods to a short-term dataset of in-situ measurements showed that propagating measured 2D frequency-direction spectra using SWAN yielded the most accurate predictions for all wave parameters. The other methods resulted in increased errors in wave direction, particularly for shore-oblique and bimodal wave climates due to underestimation of refraction.The video images together with the hourly wave conditions at shallow water in front of Castelldefels beach (obtained with the optimal propagation method) were subsequently used to investigate the dynamics of crescentic bars and megacusps as well as the corresponding coupling. Crescentic bars were present during 48% of the study period, but only when the bar-shoreline distance exceeded 10 m. They showed a wide range in wavelengths (100¿700 m), alongshore migration speeds (0¿50 m/day) and cross-shore amplitudes (5¿20 m). Low-medium energetic waves with limited obliquity (¿ = 20° at 10-m depth) dominated during crescentic bar formation, whereas medium-high energetic waves with strong obliquity (¿ = 15°) prevailed during their straightening. These observed angle ranges contradict the results of existing models. Megacusps were present during 24% of the study period and crescentic bars were present during 91% of all days with megacusps, whilst megacusps only occurred during 50% of all days with crescentic bars. Megacusp and crescentic bar wavelengths were similar (100-700 m), but the cross-shore amplitudes (3-8 m) and alongshore migration speeds (0-15 m/day) of the former were significantly smaller. Megacusp dynamics were not strongly linked to wave conditions and they mostly developed a few days after the formation of a crescentic bar, confirming that the presence of the latter induces megacusp formation. Significant sandbar-shoreline coupling was observed during 74% of the time when megacusps and crescentic bars occurred simultaneously. The type of coupling pattern was variable and depended on the wave height and angle, as they probably determine the flow pattern over the inner crescentic bar (single or double rip cell circulations versus meandering currents). Overall, this thesis shows that crescentic bar dynamics strongly depend on the wave direction and initial bathymetric configuration, highlights the strong dependence of megacusp development on crescentic bar presence and provides some ideas regarding the underlying coupling mechanisms.

DOCTORAL DEGREE IN COMPUTER ARCHITECTURE

  • KELLER, KAI RASMUS: Resilience for large ensemble computations
    Author: KELLER, KAI RASMUS
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN COMPUTER ARCHITECTURE
    Department: (DAC)
    Mode: Normal
    Deposit date: 02/06/2022
    Reading date: 01/07/2022
    Reading time: 16:00
    Reading place: fib - UPC C6-E106 - FIB
    Thesis director: BAUTISTA GOMEZ, LEONARDO ARTURO
    Committee:
         PRESIDENT: COOPERMAN, GENE
         SECRETARI: MARTORELL BOFILL, XAVIER
         VOCAL NO PRESENCIAL: MENESES, ESTEBAN
    Thesis abstract: With the increasing power of supercomputers, ever more detailed models of physical systems can be simulated, and ever larger problem sizes can be considered for any kind of numerical system. During the last twenty years the performance of the fastest clusters went from the teraFLOPS domain (ASCI RED: 2.3 teraFLOPS) to the pre-exaFLOPS domain (Fugaku: 442 petaFLOPS), and we will soon have the first supercomputer with a peak performance cracking the exaFLOPS (El Capitan: 1.5 exaFLOPS). Ensemble techniques experience a renaissance with the availability of those extreme scales. Especially recent techniques, such as particle filters, will benefit from it. Current ensemble methods in climate science, such as ensemble Kalman filters, exhibit a linear dependency between the problem size and the ensemble size, while particle filters show an exponential dependency. Nevertheless, with the prospect of massive computing power come challenges such as power consumption and fault-tolerance. The mean-time-between-failures shrinks with the number of components in the system, and it is expected to have failures every few hours at exascale. In this thesis, we explore and develop techniques to protect large ensemble computations from failures. We present novel approaches in differential checkpointing, elastic recovery, fully asynchronous checkpointing, and checkpoint compression. Furthermore, we design and implement a fault-tolerant particle filter with pre-emptive particle prefetching and caching. And finally, we design and implement a framework for the automatic validation and application of lossy compression in ensemble data assimilation. Altogether, we present five contributions in this thesis, where the first two improve state-of-the-art checkpointing techniques, and the last three address the resilience of ensemble computations. The contributions represent stand-alone fault-tolerance techniques, however, they can also be used to improve the properties of each other. For instance, we utilize elastic recovery (2nd contribution) for mitigating resiliency in an online ensemble data assimilation framework (3rd contribution), and we built our validation framework (5th contribution) on top of our particle filter implementation (4th contribution). We further demonstrate that our contributions improve resilience and performance with experiments on various architectures such as Intel, IBM, and ARM processors.

DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING

  • SADROLODABAEE, PAYAM: Sustainability, Durability and Mechanical Characterization of a New Recycled Textile-Reinforced Strain-Hardening Cementitious Composite for Building Applications.
    Author: SADROLODABAEE, PAYAM
    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: 27/05/2022
    Reading date: 11/07/2022
    Reading time: 12:00
    Reading place: Sala O.C. Zienkiewicz, Edifici C1, Planta 2a.C - Centre Internacional de Mètodes Numèrics a l'Enginyeria (CIMNE) - Gran Capità s/n, 08034 Barcelona
    Thesis director: DE LA FUENTE ANTEQUERA, ALBERTO | CLARAMUNT BLANES, JOSEP
    Committee:
         PRESIDENT: PLIZZARI, GIOVANNI
         SECRETARI: PUJADAS ÁLVAREZ, PABLO
         VOCAL: FARINA, ILENIA
    Thesis abstract: Cementitious materials have one of the highest compressive strength-to-weight ratios compared to other construction materials. Nonetheless, both tensile strength capacity and toughness result to be an order of magnitude less respect to the former, which thereby leads to cracking under tensile stresses caused by service loads. This lack of tensile strength capacity of the material leads to cracking and fragile failure in case the material is insufficiently reinforced. Within this context, fibers can be used in cementitious matrices aiming at enhancing the toughness, energy absorption capacity, post-cracking behavior as well as flexural and tensile strength.Although during the past decades, various types of fibers such as asbestos, steel, glass, and polymeric have been tested in brittle matrices, there have been some disadvantages such as detrimental health effects, high cost, and specifically, substantial environmental footprint. Likewise, based on the statistics, the construction sector is responsible for about 40% of the European Union's total final energy consumption, 35% of its total CO2 emissions, and 45% of waste generation. That is why significant efforts should be devoted to applying the `3Rs¿ concept of reducing, reusing, and recycling in the building sector and material fabrication.On the other hand, the textile leftover is one of the predominant waste resources worldwide while only less than 20% is being recycled. The textile industry produces textile wastes (TW) from the primary stages of garment production (pre-consumer waste such as fiber, yarn, and fabric) to the end of its useful life (post-consumer waste: discarded clothes). Thus, the reuse of this textile waste in construction is becoming interesting and convenient due to the shortage of natural mineral resources and increasing waste disposal costs.Recently, sustainable fibers produced from renewable, biodegradable, waste, recycled, available, and low-cost resources becoming a focal point. In this sense, vegetable and cellulosic fibers have already been used as reinforcement in cementitious materials for low- to medium-performance structural applications. TW fiber could be another sustainable alternative for reinforcement in cementitious composites.In view of the abovementioned, this research comprehensively verifies, by means of physical, mechanical, and durability-based material characterization tests, the possibility of incorporation of short TW fiber as well as the nonwoven TW fabric in the cementitious composites as internal reinforcement to produce a sustainable, ductile, and durable composite to be used in building applications. In this regard, several experimental tests were carried out on different mix design samples to characterize the mechanical, microstructural, durability, thermal, acoustic, fire, and shrinkage properties.The results have shown that the recycled TW fiber, especially in the form of nonwoven fabric, could be a technically feasible, sustainable, and durable reinforcement to be used in the cementitious mortar for low to medium-performance structural applications (e.g., façade panels, roofing, raised floors, and masonry structures). Further, the sustainability of the optimum composite as a façade cladding panel (as an example of one projected application) was assessed through the MIVES, a new comprehensive and integrated Multi-Criteria Decision-Making method that embraces the three pillars of sustainability: economic, environmental, and social.Future works on this kind of fiber-reinforced cementitious mortar could be to develop a numerical model simulation or produce a 3D concrete printing (3DCP) prototype by employing additive manufacturing technology.

DOCTORAL DEGREE IN ELECTRIC ENERGY SYSTEMS

  • ABDOLLAHI, MOSTAFA: Improving Grid Stability by Integration Renewables using Static Synchronous Generators
    Author: ABDOLLAHI, MOSTAFA
    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 ELECTRIC ENERGY SYSTEMS
    Department: (DEE)
    Mode: Normal
    Deposit date: 27/04/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: CANDELA GARCIA, JOSE IGNACIO | ROCABERT DELGADO, JOAN
    Committee:
         PRESIDENT: FERRAMOLA, JUAN MANUEL MAURICIO
         SECRETARI: LUNA ALLOZA, ALVARO
         VOCAL: BOUCHAKOUR, SALIM
    Thesis abstract: The European Commission has plans to transition from classic power system to a net-zero emission power system, mainly by focusing on renewable sources. The power plants owners and power grid operators have technical challenges to achieve this goal.The used renewables technology is one of key challenges. The active power dynamic stability, generation frequency regulation, voltage stability issues, and reactive power balancing are main technical challenges.This Ph.D. thesis proposes a new technology for operation, control, and grid connection of renewable power plant that suports power system dynamic stability during energy transition. The proposed technology is emulation of classic synchronous machine in control loops of electronic power converters, and it provides a feasible operation of a renewable static synchronous generator (SSG) based on synchronous power controller (SPC).The proposed technology (RSSG-SPC) has flexibility and can comply with grid codes. The SPC technique is the core of RSSGSPC technology. So, there are two main parts in RSSG-SPC. The electromechanical part emulates performance of synchronous power generation. This part provides virtual damping and virtual inertia functionalities and it contributes to active power control and frequency regulation. The second part is virtual admittance which provides the control of a voltage source converter in current mode.So, the converter can be modeled such as Thevenin model of synchronous generator. This part provides reactive power control and voltage regulation. The theory of RSSG-SPC, control layers modeling, and RSSG SPC¿s grid connection modeling are illustrated. The RSSG-SPC¿s operations to overcome technical challenges during grid connection, RSSG-SPC¿s flexibilities to comply with grid codes, and RSSG-SPC¿s capabilities to support dynamic stability have been discussed.The performance of renewable power plant based on RSSG-SPC technology has been evaluated by doing detailed mathematical analysis, dynamic modeling, time domain simulation, and laboratory tests validations. The RSSG-SPC grid connection is analyzed for several network topologies and different RSSG-SPC operations including, i) RSSG-SPC connected to simple bus supported by weak grid either while bus is supported by a stiff grid, ii) RSSG-SPC operates to support a long ac transmission system, iii) RSSGSPC contributes in a unique generation area system (IEEE 14B), iv) RSSG-SPC operates as big generation plant and supports a multi area generation system (Kundur¿s system), and v) RSSG-SPC operates as a small generation unit in Kundur¿s system.An algorithm is developed for implementation and modeling of RSSG-SPC in the noted applications. The algorithm covers RSSGSPC grid connection modeling taking to account the parameters of RSSG-SPC and power grid. The dynamic indices are proposed for tuning of RSSG-SPC¿s dynamic parameters (virtual inertia and virtual damping) aiming to have a stable operation of RSSG-SPC.Also, considering the real situation of power grid, adequate modifications are applied to RSSG-SPC¿s control layers leads to provide adaptable operation of RSSG-SPC in the grid connection mode. Moreover, an active power limiter is proposed to solve the power transfer limitation of renewables and to provide functionalities to follow the grid operators balancing signals.

DOCTORAL DEGREE IN ELECTRICAL ENGINEERING

  • LLEDÓ PONSATI, TOMÀS: Modular platform for research in microgrids
    Author: LLEDÓ PONSATI, TOMÀS
    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: 25/05/2022
    Reading date: 15/07/2022
    Reading time: 09:00
    Reading place: ETSEIB-UPC, Aula Capella
    Thesis director: MONTESINOS MIRACLE, DANIEL | GALCERAN ARELLANO, SAMUEL
    Committee:
         PRESIDENT: ACKVA, ANSGAR
         SECRETARI: SUMPER, ANDREAS
         VOCAL: DIETZ, ARMIN
    Thesis abstract: The present Ph.D. thesis has been developed following an Industrial Ph.D. program and verses on developing a commercial piece of equipment for teknoCEA, a spin-off company from CITCEA-UPC. The thesis is centered on developing power electronics-based emulation systems for research in microgrids. Lately, the use of power electronics-based emulation systems is drawing substantial attention in the field of microgrids because their characteristics substantially facilitate research in laboratory facilities.First, the suitability of different topologies for implementing an emulation platform is analyzed. The focus is set on the topologies adjustability to implement various types of emulation systems. The analysis determines the most appropriate number of legs for the platform. A comparative analysis is done between two-level and multi-level topologies to determine their suitability based on different aspects. Moreover, the analysis confirms the usefulness of wide-bandgap semiconductors for this type of application.Next, a control structure is proposed together with its implementation in a low-cost microcontroller based on a modular software architecture. The control strategy based on fractional proportional resonant controllers for AC emulation systems provides a control system with high control bandwidth while keeping a low computational cost. The control strategy for DC emulation systems is provided to reach a fast transient response and immunity to external disturbances, which is key for good emulation of electric systems.The modular software architecture provides a software framework easily adjustable to the needs of multiple emulation systems. That allows the implementation of the multiple control strategies with minimum changes. Additionally provides a graphical representation of the software architecture from a static and dynamic point of view.Last, the reliability of the proposed platform is assessed based on the reliability curves provided in the literature. The reliability analysis is centered on the semiconductors and capacitors. It provides evidence that emulation systems typical currents and voltages clearly affect their reliability. For the capacitors reliability assessment, a thermal modeling methodology is proposed to overcome the limitations of standard approximations. The methodology is based on anisotropic modeling of the capacitor winding. Finally, the reliability analysis establishes the guidelines to assess the platform reliability if a given mission profile is provided.
  • MARTÍNEZ REYES, JIMMY ARTURO: Remaining useful life and fault detection models for high voltage electrical connectors focused on predictive maintenance
    Author: MARTÍNEZ REYES, JIMMY ARTURO
    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: 31/05/2022
    Reading date: 08/07/2022
    Reading time: 11:30
    Reading place: ESEIAAT-UPC, Edifici TR5, Sala de Juntes- Campus Terrassa
    Thesis director: RIBA RUIZ, JORDI ROGER | MORENO EGUILAZ, JUAN MANUEL
    Committee:
         PRESIDENT: ESTEVE PUJOL, JOAN
         SECRETARI: BOGARRA RODRIGUEZ, SANTIAGO
         VOCAL: CAPELLI, FRANCESCA
    Thesis abstract: In recent years, industries have chosen to invest in technology with the aim of making their processes more efficient and thus offering market products of higher quality. Nowadays it is very common for companies to use special systems to predict failures and avoid unexpected delays, reduction of costs, etc. SBI Connectors, along with the Universitat Politècnica de Catalunya, have beencollaborating to develop research projects for more than 10 years. As a result of the collaboration with the university, patents and international publications have been generated, which have helped to situate and reinforce SBI Connectors leadership in the international market while offering an image of scientific-technical credibility. This research is carried out, with the collaboration of SBI connectors and Universitat Politècnica de Catalunya, in order to develop the Smartconnector project (within the Retos de Colaboración Spanish research frame). The thesis proposed by the author is dedicated to develop and validate RUL (Remaining Useful Life) and fault detection approaches for electrical substation connectors. The RUL approach proposed in this work is basedon a simple and accurate model of the degradation with time of the electrical resistance of the connector (main health indicator),which has two parameters, whose values are identified from on-line acquired data. Next, the fault detection chapter is divided into two parts. The first part presents an on-line condition monitoring method to predict early failures in power connectors from on-line acquired data in conjunction with another parametric degradation model of the resistance of the connector, whose parameters are identified by means of the Markov chain Monte Carlo stochastic method. The second part presents, analyzes and compares theperformance of three simple and effective methods for online determination of the State of Health (SoH) of power connectors with low computational requirements. The proposed approaches are based on monitoring the evolution of the connectors¿ electrical resistance, which determines the degradation trajectory. Furthermore, this work includes an in-depth study of the temperaturedependence of the electrical contact resistance (ECR). To analyze and validate results presented in this work, data is acquired in real time, including main parameters such as the electrical current and voltage drop across the terminals of the connector,conductor and connector temperature, thus estimating the phase shift between voltage drop and electrical current waveforms and the contact resistance by means of accelerated aging tests (ADT).
  • WESTERMAN SPIER, DANIEL: Optimal operation and design of modular multilevel converter for HVDC applications
    Author: WESTERMAN SPIER, DANIEL
    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: 18/05/2022
    Reading date: 30/06/2022
    Reading time: 15:00
    Reading place: ETSEIB-UPC, Aula 28.8 (Sala Conferències)
    Thesis director: GOMIS BELLMUNT, ORIOL | PRIETO ARAUJO, EDUARDO
    Committee:
         PRESIDENT: TEDESCHI, ELISABETTA
         SECRETARI: CEBALLOS RECIO, SALVADOR
         VOCAL: TEIXEIRA PINTO, RODRIGO
    Thesis abstract: Modular Multilevel Converters (MMCs) are a type of Voltage Source Converter (VSC) which have become the preferred topology choice for High Voltage Direct Current (HVDC) applications. Compare to its HVDC converter predecessors, such as the Line Commutated Converter (LCC), the MMC can control active and reactive power independently, requires smaller filter reactors and have blackstart capabilities. Regarding classical two- and three-level VSCs, the MMC has improved efficiency, easier scalability to higher voltage levels and better AC output voltage harmonic content. However, they need more complex regulation strategy due to its increased number of degrees of freedom (DOFs). Nevertheless, when these DOFs are fully exploited, the MMC can provide better responses than classical converters, especially during unbalanced network conditions. First, an in-depth steady-state mathematical analysis of the converter is performed to identify all its DOFs. Based on the DOFs and the currents imposed by them, the equations for the power transfer between the DC/AC networks and internally, between the upper and lower arms and among the phase-legs, are obtained. The resultant expressions indicate potential interactions between distinct DOFs. By taking advantage of those interactions, it is possible to improve existing circulating current reference calculation methods. Thus, enhancing the MMC response under balanced and unbalanced AC network conditions. The performance of the MMC can be further improved when optimization algorithms are used to calculate its references, in which this thesis proposed two different methods. In the initial proposal, an optimization-based current reference calculation in the natural $abc$ reference frame is presented. It considers the Transmission System Operator (TSO) requirements during AC network voltage sags in the form of active/reactive current set-points to provide Fault Ride Through (FRT) capability and the converter limitations. However, due its highly nonlinear characteristics it presents a high computation burden not allowing it to be solved in real-time applications. To cope with this issue, a second method is introduced whereby modifications are performed in the previous optimization formulation and linearization techniques are employed. The resultant linearized optimization-based reference calculation is then integrated with an energy-based control for MMCs and different case studies are analyzed to validate its performance compared to classical approaches.Finally, an optimization-based methodology to design the submodule (SM) capacitors is proposed. The algorithm considers all the DOFs of the MMC in order to size the SM capacitor while meeting the TSO's requirements and the converter's design limitations. The suggested method is compared with classical approaches for different operating points, and it is further exploited by considering AC network voltage sag conditions.

DOCTORAL DEGREE IN ELECTRONIC ENGINEERING

  • ALFARO ARAGÓN, CARLOS ARTURO: Una nueva perspectiva del modelado y control de microrredes eléctricas y convertidores de potencia
    Author: ALFARO ARAGÓN, CARLOS ARTURO
    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: 02/05/2022
    Reading date: 28/06/2022
    Reading time: 12:00
    Reading place: EPSVG - Videoconferència https://meet.google.com/chf-vxcd-enn
    Thesis director: GARCIA DE VICUÑA MUÑOZ DE LA NAVA, JOSE LUIS | GUZMAN SOLA, RAMON
    Committee:
         PRESIDENT: FIGUERES AMORÓS, EMILIO
         SECRETARI: CASTILLA FERNANDEZ, MIGUEL
         VOCAL: GARCERÁ SANFELIU, GABRIEL
    Thesis abstract: This doctoral thesis focuses on the modeling and control of electrical microgrids and triphasic converters. The starting points of this research work are based on previous work on modeling electrical microgrids working in isolated mode, and on the theoretical basis of control based on the slope method, widely studied in electrical microgrids. In addition, this work is basedon previous work on predictive control applied to three-phase converters, and on the theoretical bases of this type of control widely used in Power Electronics. The main contribution of this doctoral thesis is the deduction of a large-signal mathematicalmodel that describes the dynamics of the active and reactive powers that flow through converters connected in the microgrid.This proposal will make it possible to obtain new control techniques for three-phase converters connected in microgrids, suchas model-based predictive control, for example. It should be noted that the use of this model can be used as a tool to deducethe global stability of the microgrid. The systems treated in this thesis are a three-phase rectifier with a unity power factor anda three-phase microgrid composed of five three-phase inverters.
  • CANZIANI AMICO, FRANCO: Design and Implementation of Rural Microgrids ¿ Laguna Grande Case Study
    Author: CANZIANI AMICO, FRANCO
    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: 31/03/2022
    Reading date: 22/07/2022
    Reading time: 11:00
    Reading place: EPSEVG - Aula màster
    Thesis director: CASTILLA FERNANDEZ, MIGUEL | MIRET TOMAS, JAUME
    Committee:
         PRESIDENT: FIGUERES AMORÓS, EMILIO
         SECRETARI: GARCIA DE VICUÑA MUÑOZ DE LA NAVA, JOSE LUIS
         VOCAL: GARCERÁ SANFELIU, GABRIEL
    Thesis abstract: In 2015 the United Nations established the 17 Sustainable Development Goals: a set of interrelated objectives and a guide to reach a more sustainable and higher quality future for all humanity.The goals were set with a timeline for 2030, the seventh goal refers specifically to the universal access to ¿affordable and clean energy¿. Taking account the considerable fraction of world population that do not have access to electricity, especially in rural areas, this goal still requires a great effort and investment.Rural hybrid microgrids, that integrate and manage solar and wind energy resources to provide electricservice to remote locations, are a promising solution to reach this ¿last mile¿ scenario. However, as is reported in the literature, there is still scarce information about the performance of these systems based on measured data obtained in real working field conditions. This work aims to contribute to this aspect mainly by analyzing the data obtained in the 9 kW Laguna Grande community hybrid microgrid, which is cooperative since 2016 in the coast of Perú, and has been equipped with sensors and data acquisitionsystems that measure and register solar radiation, wind speed, temperatures, and all the relevant electric parameters.As a preliminary study, the rural electrification gap and costs are assessed, as well as the availability of solar and wind resources in the area of interest. A literature and state of the art review is undertaken followed by the definition of the microgrid concept and the different ways in which a rural microgrid can be configured. The particular way in which the Laguna Grande microgrid is configured and instrumented is described. Measured meteorological conditions as solar radiation, wind speed and temperature are analyzed and related to the power generated by the photovoltaic arrays and wind turbine. This in turn leads to a balance with respect to the power delivered to the community and consequently to the voltage levels of the battery bank. Battery dynamics concepts are used to determine the depth of discharge (DOD) of the batteries in a real time regime. The statistics of the DOD values allows for the duration of the battery to be estimated which is a key factor to the microgrid economics and reliability.A parametric study is done to assess the effect of varying battery size on the technical andeconomic performance of the microgrid; similarly, with generating capacity in both photovoltaic arraysand wind turbines. Complementarily, a commercial software is used to optimize the microgrid, introducing state of the art components as lithium-ion batteries, power electronics and photovoltaic modules for a future upgrade. Finally, this study would not be complete without emphasizing the importance and adequate consideration of the human factor for the success and long-term sustainability of rural electrification projects.
  • CISNEROS FERNÁNDEZ, JOSE AGUSTÍN: Low-Power High-Channel-Count CMOS ROICs for Multiplexed Arrays of Graphene Transistors in Large-Area µECoG
    Author: CISNEROS FERNÁNDEZ, JOSE AGUSTÍN
    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: 27/04/2022
    Reading date: 07/07/2022
    Reading time: 09:00
    Reading place: ETSETB https://conectaha.csic.es/b/jos-rps-e4e-txl
    Thesis director: SERRA GRAELLS, FRANCESC | GUIMERA BRUNET, ANTON
    Committee:
         PRESIDENT: DELGADO RESTITUTO, MANUEL
         SECRETARI: MOLL ECHETO, FRANCESC DE BORJA
         VOCAL: MORA LOPEZ, CAROLINA
    Thesis abstract: There is an increasing interest on the development of neural interfaces able to decipher the neural activity across multiple regions of the brain. The ultimate goal is understanding how the underlying brain dynamics drive the cognitive activities, such learning and moving or the response towards impairing diseases. Despite the huge advance in neuroscience, there is still a lack of knowledge for a complete conception of the brain, mainly because the neural activity spans over a wide range of temporal and spatial resolutions making it difficult to be recorded with a single technology.The electrical nature of the brain activity makes electrophysiology of paramount importance for the deep study of brain dynamics. Indeed, the current state-of-art invasive electrophysiological techniques include intracortical monolithic CMOS ROICs able to resolve the neural activity from single neurons, and epicortical hybrid MEAs for the recording of µECoG signals. The monolithic solutions have benefited from the scalability of CMOS technologies, with on-chip recording sensors and circuits, while hybrid neural interfaces still suffer from the point-to-point connectivity limitations and they have been mainly focused on exotic materials and discrete electronics.This PhD thesis explores novel multiplexing techniques for graphene active sensing arrays by means of tailored ROIC architectures and mixed-signal CMOS circuits, which extend the state-of-art coverage to larger areas with high-density neural interfaces by solving the current connectivity restrictions of hybrid systems. In this sense, this research presents two 1024-channel ROIC demonstrators in 1.8-V 180-nm CMOS technology representing a substantial increment on the channel count in hybrid systems while keeping the system integration at low cost and low complexity.The first research line, proposes a conservative approach based on a time-domain multiplexing scheme to minimize the connectivity for G-SGFET-only sensor arrays by moving the selection switches to the CMOS ROIC. Apart from solving the connectivity issue, the proposed multiplexing scheme is able to reduce the array technological complexity while preserving the demonstrated DC-coupled neural recording capability of G-SGFET sensors. Moreover, a modular ROIC architecture and accompanying CMOS circuits are introduced to overcome the main design challenges on channel-count scalability, like individual offset current cancellation or the degradation of the AFE noise figures. In addition, electrical tests together with in-vivo experimental results are presented to support the system capabilities of this first complete state-of-art hybrid ROIC specially designed for G-SGFET sensors.The second research line proposes a novel frequency-domain multiplexing technique capable of exploiting the intrinsic mixer capabilities of the graphene transistor to achieve a truly switch-less operation of high-channel-count G-SGFET-only probes. The mixing process allocates in continuous time the desired neural signal from the gate of the sensor into a desired frequency band avoiding both CMOS flicker noise and sampled noise folding. Scalability in this state-of-art advancement is reached by means of a custom modular ROIC architecture and specific CMOS circuit blocks. Indeed, the solutions are presented for the main design challenges in terms of generation of the required harmonic carriers and optimization of the shared full scale occupancy. The resulting neural interface is still DC coupled and capable of infra-slow recording. Finally, electrical test and in-vivo experiments are reported to support the working hypothesis.
  • LUMBRERAS CARRASCO, DAVID: Development of an active power filter based on wide-bandgap semiconductors
    Author: LUMBRERAS CARRASCO, 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 ELECTRONIC ENGINEERING
    Department: Department of Electronic Engineering (EEL)
    Mode: Normal
    Deposit date: 27/05/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: ZARAGOZA BERTOMEU, JORDI | MON GONZÁLEZ, JUAN
    Committee:
         PRESIDENT: ROMERO CADAVAL, ENRIQUE
         SECRETARI: LAMICH AROCAS, MANUEL
         VOCAL: ESPINA MASRAMON, JORGE
    Thesis abstract: Electrical and electronic equipment needs sinusoidal currents and voltages to function properly. Equipment such as computers, household appliances, electric vehicle chargers, and LED lights can distort the grid and worsen grid quality. Distorted electrical grids can cause malfunctions, reduce service life, and decrease the performance of connected equipment. Industry commonly solves these problems using active power filters, which can minimise the harmonics of the grid, eliminate undesirable reactive power, and restore balance to unbalanced power grids.This thesis deals with the design and implementation of an active power filter based on wide-bandgap semiconductors, which have properties that are superior to classical silicon devices. An active power filter¿s design must take advantage of these benefits to build converters that are smaller, more efficient, and consume fewer resources. However, wide-bandgap semiconductors also present design challenges. Because the most commonly used active power filters in the industry are based on two-level voltage source converters, the research for this doctoral thesis focuses on this converter topology. Moreover, its main objective is to contribute new modulation techniques that are specially designed to work with wide-bandgap semiconductors. The proposed modulations consider different aspects, such as the computational cost of the algorithms, converter losses, and the electromagnetic distortion generated.First, this thesis presents a hexagonal sigma-delta (H-S¿) modulation based on sigma-delta (S¿) modulation. The properties of this modulation are studied, and the technique is compared with other widely used modulations. The comparison considers efficiency, harmonic distortion, the electromagnetic compatibility of the converter, and the type of wideband semiconductor used. In addition, a fast algorithm is mathematically developed to simplify the presented modulation and reduce its computational cost.Secondly, this thesis presents a family of sigma-delta modulations specially designed to improve electromagnetic compatibility: the reduced common-mode voltage sigma-delta (RCMV-S¿) modulations. These modulations avoid using the vectors that generate the maximum common-mode voltage, which significantly reduces the generated electromagnetic distortion without affecting the performance of the converter and its harmonic distortion. Finally, the proposed modulations are applied in a wide-bandgap power converter working as an active filter. Thus, it is verified that the techniques presented in this thesis will obtain satisfactory results when implemented in commercial active power filters.
  • 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.

DOCTORAL DEGREE IN ENVIRONMENTAL ENGINEERING

  • BERETTA, MATTIA: Use for Advanced Analytics for Health Estimation and Failure Prediction in Wind Turbines
    Author: BERETTA, MATTIA
    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: 08/06/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: CUSIDO ROURA, JORDI | CARDENAS ARAUJO, JUAN JOSE
    Committee:
         PRESIDENT: SOLE CASALS, JORDI
         SECRETARI: POZO MONTERO, FRANCESC
         VOCAL NO PRESENCIAL: RENGIFO, FABIO ANDRADE
    Thesis abstract: The energy sector has undergone drastic changes and critical revolutions in the last few decades.Renewable energy sources have grown significantly, now representing a sizeable share of the energy production mix. Wind energy has seen increasing rate of adoptions, being one of the moreconvenient and sustainable mean of producing energy. Research and innovation have helpedgreatly in driving down production and operation costs of wind energy, yet important challengesstill remain open. This thesis addresses predictive maintenance and monitoring of wind turbines,aiming to present predictive frameworks designed with the necessities of the industry in mind.More concretely: interpretability, scalability, modularity and reliability of the predictions arethe objectives ¿together with limited data requirements¿ of this project. Of all the availabledata at the disposal of wind turbine operators, SCADA is the principal source of information uti-lized in this research, due to its wide availability and low cost. Ensemble models played an im-portant role in the development of the presented predictive frameworks thanks to their modularnature which allows to combine very diverse algorithms and data types. Important insights gained from these experiments are the beneficial effect of combining multiple and diverse sources of data ¿for example SCADA and alarms logs¿, the easiness of combining different algorithms and in-dicators, and the noticeable gain in predicting performance that it can provide. Finally, given thecentral role that SCADA data plays in this thesis, but also in the wind energy industry, a detailedanalysis of the limitations and shortcomings of SCADA data is presented. In particular, the ef-fect of data aggregation ¿a common practice in the wind industry¿ is determined developing amethodological framework that has been used to study high¿frequency SCADA data. This leadto the conclusion that typical aggregation periods, i.e. 5¿10 minutes that are the standard in windenergy industry are not able to capture and maintain the information content of fast¿changingsignals, such as wind and electrical measurements.
  • 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
  • RUEDA HERNÁNDEZ, ESTEL: Optimization of bioplastics production from cyanobacteria
    Author: RUEDA HERNÁNDEZ, ESTEL
    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: Temporary seizure
    Deposit date: 02/06/2022
    Reading date: 18/07/2022
    Reading time: 11:30
    Reading place: EEBE - Sala polivalent del Edifici A (A0.3)
    Thesis director: GARCIA SERRANO, JOAN
    Committee:
         PRESIDENT: STEYER, JEAN-PHILIPPE
         SECRETARI: DOSTA PARRAS, JOAN
         VOCAL: BELLUCCI, MICOL
    Thesis abstract: Polyhydroxybutyrate (PHB) is one of the most interesting alternatives to conventional plastics, because it has similar properties to polypropylene, it is more biodegradable than other bioplastics, it has really low CO2 and O2 permeability. Cyanobacteria are a promising alternative to produce PHB, as they produce it from CO2 and sunlight. However, cyanobacteria PHB biosynthesis should be optimized in order to achieve a cost-effective and environmentally friendly PHB production process. The present PhD thesis aims to contribute to the creation of new strategies and tools to enhance the PHB accumulated in wastewater borne cyanobacterial. The overall content of this PhD thesis is divided in 4 parts. The first part evaluated the effect of different cultivation conditions. In this section, different cyanobacteria were isolated from microalgae-based wastewater treatment plants. Then, the effect of inorganic carbon, salinity, light availability, initial P content in the biomass and acetate concentration on the PHB production with the isolated strains was evaluated. In the second part, the ability to keep cyanobacterial dominance and produce PHB using agricultural run-off as a source of nutrients was evaluated during 7 months in a demonstrative facility (11 m3). In the third part, a new mathematical model to predict the PHB production with cyanobacteria. Finally, in the forth part, the environmental impacts of this process were evaluated using the life cycle assessment methodology. From the first part of this PhD thesis, it was concluded that the addition of high amounts of inorganic carbon (2 gC L-1 of NaHCO3), stimulated the PHB production with cyanobacteria. However, this stimulation was related to the increase of salinity rather than to the carbon availability. Moreover, it was observed a correlation between the genes related with the glycogen catabolism and the PHB synthesis, indicating that accumulated glycogen is an important source of carbon for the production of PHB with cyanobacteria. On the other hand, high light intensities were seen to increase the PHB productivity. Finally, thepresence of acetate was seen to strongly stimulate the PHB content. After optimization of the cultivation conditions, it was found that for Synechocystis sp. the optimal concentrations were 1.2 g L-1 of acetate, 4 gC L-1 of inorganic carbon, 18 g L-1 of NaCl and 0 days in darkness. Similarly, for Synechococcus sp. 1.2 g L-1 of acetate, 0.05 gC L-1 of inorganic carbon, 9 g L-1 of NaCl and 0 days in darkness were needed. Applying this condition a maximum of a 26.1 %dcw of PHB was obtained by Synechococcus sp.The second part of this thesis shows that cyanobacteria can be successfully maintained in a demonstrative plant using agricultural run-off as a source of nutrients. In these experiments, a maximum content of a 4.5 %dcw was reached. The new developed mathematical model was calibrated for Synechocystis sp. and used to maximize the process productivity. Using first, a reactor with a hydraulic retention time of 4 days to grow cyanobacteria, and secondly a reactor with a hydraulic retention time of 20 days was applied to enhance the PHB accumulation. 50 mgN·L-1 and 10 mgP·L-1 were the optimal nutrients concentrations in the influent.Finally, in the last part of this thesis, the environmental impact results show that the use of wastewater as a source of nutrient could reduce between a 2-65% the environmental impact of this process. On the other hand, an increase in the PHB content could reduce the impact between a 46-71 %. Throughout this thesis, different strategies and tools have been provided to optimize the PHB production with cyanobacteria. However, many research advances are still needed to attain a fully viable industrial PHB production process with cyanobacteria, especially in the further enhancement of the PHB productivity and the improvement of the purification of PHB from cyanobacteria.

DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING

  • OORTHUIS GÓMEZ, RAÜL: Monitoring and analysis of soil-vegetation-atmosphere interactions at slope and catchment scale.
    Author: OORTHUIS GÓMEZ, RAÜL
    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: Normal
    Deposit date: 30/05/2022
    Reading date: 19/07/2022
    Reading time: 11:00
    Reading place: ETSECCPB-UPC, Campus Nord C/Jordi Girona, 1-3 08034 Barcelona Building C2. Classroom: 212
    Thesis director: HURLIMANN ZIEGLER, MARCEL | VAUNAT, JEAN
    Committee:
         PRESIDENT: GRECO, ROBERTO
         SECRETARI: LEDESMA VILLALBA, ALBERTO
         VOCAL NO PRESENCIAL: YILDIZ, ANIL
    Thesis abstract: Slope mass-wasting (SMW) due to shallow landslides or debris flows is one of the most important erosional processes in many mountainous regions together with surficial erosion by rainfall runoff. These erosive processes cause great socioeconomic and environmental impacts. SMW is affected by soil-vegetation-atmosphere (SVA) interactions and is mainly triggered by climatic actions such as rainfall. SVA interactions involve many factors (e.g. soil type, slope topography, slope hydrological conditions and cover (e.g. bare or vegetated)) that are closely linked to slope thermo-hydro-mechanical response, and hence, to slope stability and erosion. The main aim of this work is to improve the knowledge on SVAinteractions through two monitoring systems at slope and catchment scale.At slope scale, an embankment divided in four partitions with North and South orientations and bare/vegetated slopes in each orientation has been monitored. This work has analyzed four years (2017-2020) of soil hydro-thermal and atmosphericparameters related to SVA interactions. The results show that vegetation increases rainfall infiltration, which suggests a decrease in runoff. In addition, vegetation transpiration increases soil drying rates and states, which favors slope stability.Regarding the thermal response, orientation plays an important role with higher temperatures on the South slopes. However, vegetation diminishes the incidence of solar radiation, which reduces soil heat flux up to 75% on the South-facing slopes,and hence, reduces evaporation and daily temperature fluctuations. Nevertheless, the effect of vegetation transpiration is more important than orientation in developing drier soil conditions. This is clearly observed by comparing the drying rates and hydrologic conditions of the North-vegetated slope, which are higher and dryer, with those of the South-bare slope, which are lower and wetter. The results show that vegetation has effects on the hydrologic and thermal response of slopes that may be positive or negative for SMW.At catchment scale, a monitoring system for torrential flows (debris flows and debris floods) detection and characterization has been maintained and further developed in the Rebaixader catchment (Central Pyrenees). 12 years of rainfall andtorrential flows occurrence (2009-2020) and 8 years of soil hydrological parameters (2013-2020) have been analyzed to characterize both hydrological soil conditions and rainfall characteristics necessary for torrential flows triggering. Most torrential flows are triggered by short duration (<3 hours) and high intensity (4-10 mm in 5 minutes) rainfalls. Furthermore, therainfall intensity for torrential flow initiation must be higher when the soil is dryer, and vice versa. First, rainfall thresholds based on rainfall mean intensity (Imean) and maximum intensity (Imax) are defined by means of Receiver OperatingCharacteristics and Precision-Recall curves. The Imean threshold predicted 2 false negatives and 73 false positives for the 2013-2020 dataset, which includes 15 torrential flow events. This results in a low precision of 15%, since only 13 torrentialflow out of 86 issued alarms are correctly predicted. Contrarily, the best Imax threshold reduced the false positives to 11 andpredicted also 2 false negatives, increasing the precision to 54%. Then, the hydro-meteorological thresholds were defined by combining Imax and volumetric water content. The best hydro-meteorological threshold reduced the false positives to 8 and the false negatives to 1, increasing the precision to 63%. This confirms that soil hydrological conditions play an important rolein torrential flows triggering and may improve early warning predictions.This work significantly contributed to improve our understanding on SVA interactions and its coupling with slope thermohydro-mechanical response, which is strongly related to SMW, by means of in-situ monitoring at slope and catchment scale.
  • WANG, YUFEI: Numerical Modeling of Geological Carbon Sequestration: Enhanced Dissolution in Randomly Heterogeneous Media
    Author: WANG, YUFEI
    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: Normal
    Deposit date: 24/05/2022
    Reading date: 11/07/2022
    Reading time: 11:00
    Reading place: Aula 002 Edifici C1 ETSECCPB - UPC CAMPUS NORD - C/Jordi Girona, 1-3 08034 Barcelona
    Thesis director: FERNANDEZ GARCIA, DANIEL
    Committee:
         PRESIDENT: CARRERA RAMIREZ, JESUS
         SECRETARI: SANCHEZ VILA, FRANCISCO JAVIER
         VOCAL: VILARRASA RIAÑO, VÍCTOR
    Thesis abstract: Geological Carbon Sequestration (GCS) plays a major role in mitigating the global warming due to the increasing concentration of CO2 in atmosphere. It is important to understand the GCS process to analyze and predict its influence on the CO2 reservoir site. This work firstly offers three finite difference programs for simulating the GCS process, secondly applies the program to perform quantitative analysis of the GCS, and finally gives several remarks related to the GCS. Firstly, we describe the three finite difference programs, which, to different extents, take into account the role of chemical reaction in the GCS process. The first program is a reactive two-phase flow model that only considers the interplay between brine and gas phases, which can be solved with explicit method. The second program is a simplified reactive three-phase flow model that also considers the heterogeneous reaction between mineral rock and the aqueous species, but all the chemical reactions are treated as equilibrium reactions and expressed with empirical formulas, to avoid performing grid-by-grid calculation of chemical reaction at each time step. The third program is a full reactive three-phase flow model that accounts for partial equilibrium reaction system (i.e., both equilibrium and kinetic reactions are included) as well as the pure equilibrium reaction system. In this third program, the partial equilibrium chemical system is solved with MAL, and chemical reactions and mass transport are alternately solved with Newton-Raphson method. All these programs have been approved through non-ideal benchmark test that only considers the transport issue. Secondly, the first program is employed to perform two qualitative analysis on the dissolution trapping. The first quantitative analysis focuses on the enhanced dissolution efficiency of overlying gaseous CO2 into underlying brine owing to gravity-driven convection (GDC) in the brine phase. The injected light CO2 will override the brine. Studies have shown that the dissolution is not only driven by molecular diffusion, but also enhanced by the GDC in the brine, because the dissolution of CO2 can increase the density of the brine in the upper portion. In literature, the GDC in homogeneous media has been well studied and researchers are attempting to investigate the GDC in realistic heterogeneous media. It is yet to find an efficient formula to predict the dissolution rate in heterogeneous media with anisotropic permeability distribution. This work conducts a large number of numerical simulations in various heterogeneous fields, analyzes the simulation results, and proposes two formulas that efficiently predict the dissolution rate based on geological and fluid parameters. The second quantitative analysis focuses on the enhanced dissolution trapping due to the layered permeability structure during the injection period. Results show that when buoyant forces are important, vertical segregation controls the overall behavior of CO2, diminishing the influence of small-scale heterogeneity on dissolution. However, when buoyant forces are relatively small compared to the degree of heterogeneity, CO2 migrates preferentially through high permeability layers and dissolution efficiency increases with heterogeneity due to the stretching of the CO2 plume that enhances mixing. As a result, in this situation, the upscaling of permeability leads to an underestimation of the dissolution efficiency. Additionally, we give in the appendix a parallel study on how to enhance NAPL removal and mixing with engineering chaotic advection.

DOCTORAL DEGREE IN MARINE SCIENCES

  • QUIRÓS COLLAZOS, LUCÍA: Estudio paleoclimático del afloramiento ecuatorial del Océano Pacífico durante los últimos 160.000 años a partir de biomarcadores moleculares.
    Author: QUIRÓS COLLAZOS, LUCÍA
    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: 22/04/2022
    Reading date: 27/06/2022
    Reading time: 10:00
    Reading place: ETSECCPB - Saló d'Actes Ramon Margalef de l'Institut de Ciències del Mar del CSIC.
    Thesis director: CALVO COSTA, EVA | PELEJERO I BOU, CARLES
    Committee:
         PRESIDENT: FLORES VILLAREJO, JOSE-ABEL
         SECRETARI: CERMEÑO AÍNSA, PEDRO
         VOCAL: VILLANUEVA ALVAREZ, LAURA
    Thesis abstract: The present PhD thesis is focused on the paleoclimatic reconstruction of the Pacific Ocean equatorial upwelling conditions, east of the Galapagos Islands, over the last 160.000 years. This region is of great interest to understand climate dynamics within the context of current global change, as it plays a key role in global biogeochemical cycles, especially the carbon cycle, being one of the areas with largest CO2 fluxes from the ocean to the atmosphere. In addition, studies covering the recent decades have shown that tropical regions play a key role in regulating global climate, since they control the transfer of thermal energy from low to high latitudes.This study is based on the analysis of molecular biomarkers in the marine sediment core ODP 1240, which was obtained during Leg 202 of the Ocean Drilling Program. The main analysed compounds were the long-chain ketones, known as C37 alkenones, the 24-methylcholesta-5,22-dien-3ß-ol, known as brassicasterol, long-chain n-alkanes, glycerol dialkyl glycerol tetraethers (GDGTs) and 1,14-alkyl diols.The UK'37 and TEXH86 indexes were obtained from the analyses of the mentioned biomarkers to assess their suitability as temperature proxies to reconstruct sea surface conditions at the eastern Pacific upwelling on a glacial-interglacial time scale. They reflect variations in the mean annual surface temperature at the study area and track the warming and cooling trends typical of glacial-interglacial variations, although with certain peculiarities associated with each proxy. The UK'37 derived record shows a special sensitivity to periods with La Niña-like seasonal conditions, when the upwelling was more intense and sea surface temperatures in this area were colder. On the other hand, the TEXH86 index shows a tendency to overestimate the cooling of surface waters during glacial periods, as it has been also observed in similar reconstructions in this and other tropical regions. This might be due to the combined influence of changes in surface temperature and in ammonium oxidation rates of the Thaumarchaeotas that synthesize GDGTs and proliferate in the upper water column.Paleoclimatic information provided by other records nearby indicate that changes in oceanic denitrification linked to the supply of oxygen through subsurface and intermediate waters could have a regulating effect on the availability of ammonium in surface water. This, in turn, would have led to changes in the relative abundance of the GDGTs synthesized by Thaumarchaeotas, causing a glacial cooling overestimation through the TEXH86 index.The high resolution that characterizes the ODP 1240 core has allowed gaining a more in-depth knowledge on the millennial-scale climatic variability of this region. In particular, the changes in primary production during the penultimate deglaciation have been studied. This deglaciation, known as Termination II, can be used as a laboratory to understand climate dynamics during periods of rapid global warming. The results show that phytoplankton production was enhanced by an increasing influence of nutrient-rich Southern Ocean-sourced waters and by enhanced atmospheric dust inputs, which would have served as an additional source of iron to the study region. These processes culminated during the development of the Heinrich Event 11 in the North Atlantic, at a time when the highest increase in primary productivity of Termination II was recorded in the eastern equatorial Pacific upwelling. The results of this thesis highlight the relationships between global dynamics of biogeochemical cycles and those of the eastern equatorial Pacific, as well as the role played by high to low latitude teleconnections.

DOCTORAL DEGREE IN NETWORK ENGINEERING

  • OSMAN, MOHAMMED OSMAN: Control Logic Distribution trade-offs in Software-Defined Wireless Networks
    Author: OSMAN, MOHAMMED OSMAN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN NETWORK ENGINEERING
    Department: Department of Network Engineering (ENTEL)
    Mode: Normal
    Deposit date: 18/05/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: MANGUES BAFALLUY, JOSEP
    Committee:
         PRESIDENT: AGÜERO CALVO, RAMÓN
         SECRETARI: ZOLA, ENRICA VALERIA
         VOCAL: BARANDA HORTIGÜELA, JORGE
    Thesis abstract: The SDN (Software-Defined Networks) architecture separates the data and the control planes of the networks. It logically centralizes the control of a network in a central point that is an SDN controller, which acts as a brain of the network and is in charge of telling each network node how to forward incoming packets by installing the appropriate forwarding rules. One of the main advantages it brings is programmability through this single entity (the logical controller) with which network management applications must interact to apply their policies. Through agreed-upon APIs, the network managers can exploit the full potential of SDN.SDN generally assumes ideal control channels between the SDN controller and the network nodes, which may not be the case in challenging environments that are becoming more common due to dense deployment of small cells (SCs) with reduced coverage in 5G and beyond 5G deployments. In 5G and beyond 5G use cases, cost-effective wireless transport networks are required to connect the SCs. In this context, mmWave technology is a good player to connect the SCs as mmWave provides larger radio spectrum chunks that in turn provide larger bandwidth and higher data rate.To manage the dense deployment of SCs in the mobile networks, on the network management/control front, network programmability and virtualization are also an integral part of 5G and beyond 5G networks. In this regard, to provide end-to-end connectivity, management and orchestration of all the segments of the networks ranging from RAN (Radio Access Network), transport network to the core is vital. On the transport networks side (the main focus of the dissertation), SDN plays an important role as SDN enables programmability and virtualization in the network.Though SDN Provides huge flexibility in network management by splitting the control plane from the data plane, it has some limitations in wireless networks context as separation of the control plane from the data plane introduce the extra points of failure in the SDN paradigm (e.g., control communication channel failure, SDN controller failure). In the wide-area networks (WAN) scenarios where in-band channels (e.g., microwave or mmWave links) are responsible to carry control traffic between the forwarding nodes and the SDN controller, the assumption of the availability of a reliable network may not be possible as the performance of the wireless link changes with the environmental conditions, which leads to a high risk of experiencing channel impairments, which might cause centralized SDN operation failure by affecting communication between the transport component of SCs and the SDN controller.To overcome SDN from failure, the dissertation presents a hybrid SDN scheme that explores the benefits of centralized and distributed operations depending on control communication channel conditions. Our hybrid SDN approach combines both centralized and distributed modes in the same node to form a hybrid control plane architecture. We introduce a local agent in the node that is composed of a monitoring framework to detect reliability of the control communication channel and a decision module that conceive a novel control logic switching algorithm to make a decision whether to operate in a centralized or distributed mode. We evaluate the proposed solution under a variety of unreliable network conditions (e.g., link impairments, control packet loss) to investigate the operational performance of the hybrid SDN during high loss conditions. The experimental results show that the proposed hybrid SDN solution substantially improves the aggregated throughput, particularly when control channel packet loss ratios increase, which in turn keeps the network operational in hard conditions where the centralized SDN would result in a non-operational network.
  • VINCENZI, MATTEO: Efficient Sharing Mechanisms for Virtualized Multi-Tenant Heterogeneous Networks
    Author: VINCENZI, MATTEO
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN NETWORK ENGINEERING
    Department: Department of Network Engineering (ENTEL)
    Mode: Normal
    Deposit date: 27/05/2022
    Reading date: 18/07/2022
    Reading time: 10:00
    Reading place: EETAC meet: https://meet.google.com/qsg-uffi-pzm
    Thesis director: LOPEZ AGUILERA, MARIA ELENA | GARCIA VILLEGAS, EDUARD
    Committee:
         PRESIDENT: FIORE, MARCO
         SECRETARI: DEMIRKOL, ILKER SEYFETTIN
         VOCAL: CHOUMAS, KOSTAS
    Thesis abstract: The explosion in data traffic, the physical resource constraints, and the insufficient financial incentives for deploying 5G networks, stress the need for a paradigm shift in network upgrades. Typically, operators are also the service providers, which charge the end users with low and flat tariffs, independently of the service enjoyed. A fine-scale management of the network resources is needed, both for optimizing costs and resource utilization, as well as for enabling new synergies among network owners and third-parties. In particular, operators could open their networks to third parties by means of fine-scale sharing agreements over customized networks for enhanced service provision, in exchange for an adequate return of investment for upgrading their infrastructures. The main objective of this thesis is to study the potential of fine-scale resource management and sharing mechanisms for enhancing service provision and for contributing to a sustainable road to 5G. More precisely, the state-of-the-art architectures and technologies for network programmability and scalability are studied, together with a novel paradigm for supporting service diversity and fine-scale sharing. We review the limits of conventional networks, we extend existing standardization efforts and define an enhanced architecture for enabling 5G networks' features (e.g., network-wide centralization and programmability). The potential of the proposed architecture is assessed in terms of flexible sharing and enhanced service provision, while the advantages of alternative business models are studied in terms of additional profits to the operators. We first study the data rate improvement achievable by means of spectrum and infrastructure sharing among operators and evaluate the profit increase justified by a better service provided. We present a scheme based on coalitional game theory for assessing the capability of accommodating more service requests when a cooperative approach is adopted, and for studying the conditions for beneficial sharing among coalitions of operators. Results show that: i) collaboration can be beneficial also in case of unbalanced cost redistribution within coalitions; ii) coalitions of equal-sized operators provide better profit opportunities and require lower tariffs. The second kind of sharing interaction that we consider is the one between operators and third-party service providers, in the form of fine-scale provision of customized portions of the network resources. We define a policy-based admission control mechanism, whose performance is compared with reference strategies. The proposed mechanism is based on auction theory and computes the optimal admission policy at a reduced complexity for different traffic loads and allocation frequencies. Because next-generation services include delay-critical services, we compare the admission control performances of conventional approaches with the proposed one, which proves to offer near real-time service provision and reduced complexity. Besides, it guarantees high revenues and low expenditures in exchange for negligible losses in terms of fairness towards service providers. To conclude, we study the case where adaptable timescales are adopted for the policy-based admission control, in order to promptly guarantee service requirements over traffic fluctuations. In order to reduce complexity, we consider the offline pre­computation of admission strategies with respect to reference network conditions, then we study the extension to unexplored conditions by means of computationally efficient methodologies. Performance is compared for different admission strategies by means of a proof of concept on real network traces. Results show that the proposed strategy provides a tradeoff in complexity and performance with respect to reference strategies, while reducing resource utilization and requirements on network awareness.

DOCTORAL DEGREE IN PHOTONICS

  • DE ROQUE FERNANDEZ, PABLO MANUEL: Contributions to nanophotonics: linear, nonlinear and quantum phenomena
    Author: DE ROQUE FERNANDEZ, PABLO MANUEL
    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: 06/04/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: VAN HULST, NIEK
    Committee:
         PRESIDENT: QUIDANT, ROMAIN
         SECRETARI: PAPADAKI, GEORGIA
         VOCAL: AIZPURUA IRIAZABAL, JAVIER
    Thesis abstract: Nanophotonics can be defined as the science and technology studying the control optical fields at the nanoscale and their interaction with matter. In order to spatially control such fields we would need structures with characteristic dimensions of the order of the wavelength, bringing us to the nanoscale. A way to control optical fields at this scale is the use of nanoantennas, optical equivalent of radio-antennas. They provide efficient interfaces between near-fields generated by light sources and radiative channels. After a brief Introduction, Chapter 2 describes interaction between single photon emitters and nanoantennas. We start the chapter introducing a method to numerically simulate the interaction. A key concept to solving Maxwell equations is that of the Green function. I show how this function relates to the emission rate of optical emitters in a nanophotonic environment. I then describe an our efforts to build a lifetime-imaging near-field scanning optical microscope. Using this rig we are able to measure changes changes in the emission rate of single emitters that interact with resonant optical antennas. A complementary way to control optical field in the nanoscale is using dielectric confinement. Chapter 3 introduces hybrid structures combining nanoantennas and dielectric waveguides. I generalize the Green function formalism introduced in Chapter 2, and show how this is related to the energy transfer rate between a donor and an acceptor. I use this numerical method to calculate the energy transfer rate in a hybrid structure. An increase of orders of magnitude is found at distances of the order of the wavelengths of the transferred photons. This chapter finishes by discussing the role that the local density of optical states has on the energy transfer efficiency.Nanoantennas increase near-field by orders of magnitude. In these conditions, nonlinear optical effects start to play a role. Chapter 4 is devoted to these nonlinear interactions mediated by nanoantennas. I explore nonlinear interactions in resonant nanoantennas, in particular SHG. First I introduce a method to numerically compute the contributions to SHG generated by the metal in nanoantennas. Both surface and bulk contributions to SHG are considered. I use the numerical method to show that narrowings within the antenna shape are sources of increased SHG. The increase in SHG is attributed to increase of the local field gradients, that increase to the bulk contribution to SHG. We numerically validate our results by performing SHG measurements at the single resonant antenna level.Optical fields are functions of space, but also of time. The development of broadband femtosecond lasers and pulse shaping techniques allows control of optical field down to the femtosecond timescale. Chapter 5 explores the control of optical fields in time. Using phase shaping methods we optimize the two-photon absorption process in single QDs. I introduce a new optimization algorithm, that allows us to perform the optimization using as feedback signal the luminesce from single QDs. We then compare our results with standard phase shaping techniques.Based on their success to effectively control all kinds of optical fields, plasmon supporting nanoantennas are being actively researched in the field of quantum optics. In Chapter 6 I describe a quantum eraser experiment mediated by structures supporting surface plasmon resonances. I first explain the details and subtleties of a quantum eraser experiment. I then detail our efforts to reproduce previously reported results about how to fabricate elliptical bullseye antennas behaving as quarter waveplates. Quarter waveplates are a required part for the quantum eraser effect to take place. An additional key component of our experiment is a bright, state-of-the-art entangle polarization entangle photon source that is described at length. We then perform a quantum eraser experiment mediated by plasmons.
  • HUSSAIN, RUBAIYA: Detection of particles, bacteria and viruses using consumer optoelectronic components
    Author: HUSSAIN, RUBAIYA
    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: 25/05/2022
    Reading date: 01/07/2022
    Reading time: 15:30
    Reading place: ICFO ¿ The Institute of Photonic Sciences - Campus Baix Llobregat - Av.
    Thesis director: PRUNERI, VALERIO
    Committee:
         PRESIDENT: KERSAUDY-KERHOAS, MAÏWENN
         SECRETARI: EBRAHIM-ZADEH, MAJID
         VOCAL: MANNELLI, ILARIA
    Thesis abstract: The focus of this thesis is on the design, development and validation of two novel photonic sensors for the detection and characterisation of industrial and biological samples. The first one is a PSA in a collimated beam configuration using an innovative angular spatial filter, and a consumer electronic camera similar to that used in a smartphone. The small form factor angular spatial filter allows for the collection of diffused light from particles up to predefined discrete angles. By using angularly resolved scattering images acquired by the camera, a machine learning (ML) algorithm predicts the volume median diameter of the particles. Our system has achieved a mean absolute percentage error of only 0.72% for spherical particles in solution with sizes greater than 10 µm and at concentrations up to 40 mg mL-1. Compared to traditional laser diffraction systems, the proposed PSA is an order of magnitude smaller in size, weight and cost, and offers a promising approach to online industrial process monitoring.As light scattering is influenced by factors other than particle size, including shape, refractive index contrast and suspension concentration, the PSA can also be employed in biological applications. To this end, the second part of the thesis aims to optimise the PSA for the measurement of small (< 10 µm) particles such as microorganisms. The results demonstrate that the modified PSA in combination with ML is able to accurately classify different types of bacteria (Escherichia coli and Enterococcus sp.) and distinguish them from silica beads of comparable sizes, with an accuracy of 89%. Moreover, it can detect the concentration of bacteria in water with a limit of detection (LOD) of approximately 105 cells mL-1.The final part of the thesis is dedicated to the development of a low-cost, portable optical biosensor for the specific detection of particles smaller than bacteria, such as viruses (< 1 µm). The proposed system, which we have called flow virometry reader (FVR), is a modification of a flow cytometer and relies on measuring light emissions from fluorescent antibodies that bind to specific viral particles. An LOD of 3,834 copies mL-1 for SARS-CoV-2 in saliva can be achieved with the device. The FVR is clinically validated using 54 saliva samples in a blind test, with high sensitivity and specificity of 91.2% and 90%, respectively. These findings suggest that the FVR has the potential to be a highly viable alternative to current diagnostic methods for pandemic events, as it is faster (< 30 min) and less expensive than PCR tests, while being more sensitive than today¿s COVID-19 rapid antigen tests.The photonic sensing technologies developed in the thesis show significant potential for use in a wide range of applications, including:¿ particulate air pollution, causing cardiovascular and respiratory problems¿ particulate water pollution, which affects the ecosystems of rivers, lakes and oceans¿ total bacterial count in environmental or bathing water¿ viral pandemics The technologies are particularly appealing in countries with limited resources due to their simple design, portability, short time-to-result and affordability, as well as the fact that they do not require a specialised laboratory or trained personnel to operate them.
  • JULIÀ FARRÉ, SERGI: Controlling interactions in quantum materials: from a microscopic description to quantum simulation
    Author: JULIÀ FARRÉ, SERGI
    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: 23/05/2022
    Reading date: 28/06/2022
    Reading time: 10:00
    Reading place: ICFO ¿ The Institute of Photonic Sciences - Campus Baix Llobregat - Av.Carl Friedrich Gauss, 3 08860 Castelldefels (Barcelona) - SPAIN
    Thesis director: LEWENSTEIN, MACIEJ | DAUPHIN, ALEXANDRE
    Committee:
         PRESIDENT: WEITENBERG, CHRISTOF
         SECRETARI: ASTRAKHARCHIK, GRIGORI
         VOCAL: BERMÚDEZ CARBALLO, ALEJANDRO
    Thesis abstract: The last decades have witnessed impressive technical advances in all the fields of quantum science, including solid-state systems or atomic, molecular, and optical physics, allowing one to control materials at the microscopic scale with a high degree of precision. This development opens the road for the investigation of complex many-body phenomena in quantum materials, which cannot be easily inferred from the behavior of their individual constituents. Indeed, interactions in quantum many-body systems can lead to richer physics compared to the noninteracting case, as they are deeply connected with spontaneous symmetry breaking, quantum correlations, i.e., entanglement, and some collective behaviors. On the one hand, in some cases, the motivation to study such interacting systems is the possibility to synthesize them in the lab, such as for instance with cold atoms in optical lattices. The latter platform can be used as a quantum simulator of systems that were regarded just as toy models in the last century, as it is the case of topological insulators: materials characterized by a global topological invariant leading to protected surface modes. While so far experiments have concentrated their efforts on engineering noninteracting topological insulators, state-of-the art techniques can also be used to study the role of interactions in these systems.In this context, the first goal of this thesis is to investigate novel effects in interaction-induced topological insulators. In the one-dimensional case, we reveal the topological nature of fermionic chains with frustrated interactions, which could be realized with dipolar quantum gases. For the two-dimensional case, we focus on topological Mott insulators, for which we propose an experimental scheme based on Rydberg-dressed atoms. Furthermore, we show that these systems can exhibit rich spatial features intertwined with their topological protection, owing to the interacting nature of the phase. On the other hand, there are some paradigmatic cases, as in high-Tc superconductors, where exotic experimental results clearly point towards the need of finding a microscopic model in a many-body interacting framework. In the particular case of high-Tc superconductors, their complex composition and unknown exact form of intrinsic interactions make it challenging to characterize their rich phase diagram: such materials not only host a high-Tc superconducting phase, but also other exotic phases, such as the strange metal or pseudogap phases. In this regard, the second goal of this thesis is to gain physical insight of the pseudogap phase of cuprate high-Tc superconductors. To this aim, we numerically study the effect of interactions between electrons and bond phonons within a particular Hamiltonian modeling of the system. We show that, by properly accounting for the subtle interplay between electron-electron and electron-phonon interactions, one can indeed numerically reproduce the main experimental features of the pseudogap phase.Finally, the study of collective interaction-induced effects is also needed to analyze the quantum advantage theoretically claimed for some systems. In particular, many-body interactions and entanglement are sometimes regarded as a resource for quantum thermodynamic machines: devices that perform tasks related to refrigeration, heat-to-work conversion, or energy storage. On this basis, the third goal of this thesis is to study fundamental bounds imposed by quantum mechanics to collective charging effects in systems for energy storage, called quantum batteries.
  • LIU, XINYAO: Atomic imaging of complex molecular
    Author: LIU, XINYAO
    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: 02/06/2022
    Reading date: 27/07/2022
    Reading time: 11:00
    Reading place: ICFO ¿ The Institute of Photonic Sciences - Campus Baix Llobregat - Av.Carl Friedrich Gauss, 3 08860 Castelldefels (Barcelona) - SPAIN
    Thesis director: BIEGERT, JENS
    Committee:
         PRESIDENT: GONZÁLEZ FEREZ, ROSARIO
         SECRETARI: LEWENSTEIN, MACIEJ
         VOCAL: GRÄFE, STEFANIE
    Thesis abstract: One of the significant challenges of modern science is to track and image chemical reactions as they occur. The molecular movies, the precise spatiotemporal tracking of changes in their molecular dynamics, will provide a wealth of actionable insights into how nature works. Experimental techniques need to resolve the relevant molecular motions in atomic resolution, which includes (10^(-10) m) spatial dimensions and few- to hundreds of femtoseconds (10^(-15) s) temporal resolution. Laser-induced electron diffraction (LIED), a laser-based electron diffraction technique, images even singular molecular structures with combined sub-atomic picometre and femto-to attosecond spatiotemporal resolution. Here, a laser-driven attosecond electron wave packet scatters the parent¿s ion after photoionization. The measured diffraction pattern of the electrons provides a unique fingerprint of molecular structure. Taking snapshots of molecular dynamics via the LIED technique is proved to be a potent tool to understand the intertwining of molecules and how they react, change, break, bend, etc. This thesis is especially interested in exploiting advanced LIED imaging techniques to retrieve large complex molecular structures. So far, LIED has successfully retrieved molecular information from small gas-phase molecules like oxygen (O2), nitrogen (N2), acetylene (C2H2), carbon disulfide (CS2), ammonia (NH3) and carbonyl sulfide (OCS). Nevertheless, most biology interesting organic molecules typically exist as liquid or solid at room temperature. In order to accomplish the final goal to extract these larger complex molecular structural information, we need to overcome two main challenges: delivering the liquid or solid samples as a gas-phase jet with sufficient gas density in the experiment and developing a new retrieval algorithm to extract the geometrical information from the diffraction pattern. We tested one of the most simple liquid molecules - water H2O in the reaction chamber as a primary step. We traced the variation of H2O+ cation structure under the different electric fields. To solve the problem of unsatisfactory gas density, we present a novel delivery system utilizing Tesla valves that generates more than an order-of-magnitude denser gaseous beam. Machine learning is well qualified to solve difficulties with manifold degrees of freedom. We use convolutional neural networks (CNNs) combined with LIED techniques to enable atomic-resolution imaging of the complex chiral molecule Fenchone (C10H16O).
  • ROMBAUT SEGARRA, JUAN: Multifunctional optical surfaces for optoelectronic devices
    Author: ROMBAUT SEGARRA, JUAN
    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: Temporary seizure
    Deposit date: 25/02/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: PRUNERI, VALERIO
    Committee:
         PRESIDENT: MANNELLI, ILARIA
         SECRETARI: MARTORELL PENA, JORDI
         VOCAL: ST CLAIR, TODD PARRISH
    Thesis abstract: Highly transparent optical surfaces with anti-reflection (AR) and self-cleaning properties have the potential to increase performance in a wide range of applications, such as display screens, photovoltaic cells or sensors. Nature has provided numerous examples of biological systems with interesting functionalities that have high commercial interest, from the broadband and omnidirectional anti-reflection effect created by the tiny nanopillars found on the corneas of moths¿ eyes, to the self-cleaning behaviour of lotus leaves generated by micro-and nanoprotuberances. However, despite intense academic research, replicating such elaborate nanostructures for mass-production remains a major challenge due to the limitations of the existing nanofabrication techniques based on classical optical and e-beam lithography processes. This thesis is devoted to the study of bio-inspired multifunctional nanostructured surfaces with enhanced optical and wetting properties for use in optoelectronic devices. Novel and reliable manufacturing techniques are proposed for patterning organic and inorganic materials with high precision and throughput, aiming to bring this technology out of the laboratory and making it industrially viable. The first part of this study has been centred on glass, as it is one of the most widely used materials for optoelectronic devices. Chapter 3 presents a nanopillar structure created on glass substrates, which provides high anti-reflective properties, enhanced transmission, superhydrophobicity, and high mechanical resistance against external agents. The proposed manufacturing method permits moderate tunability to adapt the structure to the requirements of different applications. The design and optimisation of the fabrication process and a full characterisation of the samples are reported. Chapter 4 describes the combination of two different anti-reflective approaches, state-of-the-art multilayer (ML) anti-reflective coatings and self-cleaning biomimetic nanostructures (NS). The classical ML coating, relying on destructive interference from multiple reflections at layer interfaces is capable of providing excellent AR properties, but with a limited wavelength range and angular acceptance. In addition, it has limited hydrophobicity and self-cleaning properties due to its flat surface. The NS coating can provide broad wavelength and angular AR properties, as well as superhydrophobicity. However, it suffers from mechanical durability issues. In this work, the combination of both methods is presented as an innovative solution, combining greater anti-reflective operational wavelength and angular acceptance, self-cleaning properties, and high mechanical durability. A nanostructured design for transparent oleophobic surfaces is investigated and experimentally demonstrated in Chapter 5. Two new fabrication techniques to create nanocavities on glass are presented. The nanohole structure can repel oil and other low surface tension liquids, and a new wetting model is developed to theoretically explain the mechanism. The porous structure modifies the effective refractive index of the nanostructured layer between the air and the glass, creating an AR effect. The samples present higher transmission, as well as low scattering due to the subwavelength size of the cavities. In addition, the geometry of the surface offers higher mechanical resistance compared to nanopillars, widening the potential applications where it could be used. Finally, in Chapter 6, a new method to nanostructure organic materials with high resolution is presented. Nanostructured thin polyimide films on top of glass surfaces can act as an anti-reflective coating, while adding protection and hydrophobicity. A practical example is demonstrated with transparent electrodes made of Indium Tin Oxide. By covering a surface with nanostructured polyimide, the overall optical response can be improved while its electric properties are protected by the polymeric film.

DOCTORAL DEGREE IN POLYMERS AND BIOPOLYMERS

  • LACRUZ CRUZ, AMADO: ECO-DWOR: ECOlogical finishing agents for Durable Water&Oil-Repellent textiles with advanced functionalities
    Author: LACRUZ CRUZ, AMADO
    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: Article-based thesis
    Deposit date: 31/05/2022
    Reading date: 18/07/2022
    Reading time: 10:30
    Reading place: Sala d'Audiovisuals del Dept. d'Enginyeria Química, ETSEIB, pavelló G, 2a planta, Campus Sud
    Thesis director: MARTINEZ DE ILARDUYA SAEZ DE ASTEASU, DOMINGO
    Committee:
         PRESIDENT: LEIZA RECONDO, JOSÉ RAMÓN
         SECRETARI: BOU SERRA, JORGE
         VOCAL: SARDON MUGURUZA, HARITZ
    Thesis abstract: Fluorinated chemicals, commonly known as per- and polyfluoroalkyt substances (PFASs), are widely used to obtain water-, oil- and stain-repellent texUles. The constant development and optimization of fluorochemicals for textile applications initiated more than five decades ago has resulted in a veryefficient DWOR-technology and texUles with exceptional hydro­ and oleo-phobic properties (DWOR acronym stands for Durable Water and Oil Repellen!). However, PFASs' high mobility, persistence and harmful health effects, has been proved by numerous scientific studies and, therefore, regulation and phase-out of severa! PFASs is being implemented bygovernm ents. At the present time the textile industry lacks suitable alternatives to fluorochemicals with comparable material characteristics.The main goal ofthis work is to design fluorine-free textile finishing agents based on sustainable polymers with low surface-tension functional groups in combination with (nano)materiaIs to confer water- and oil-repellencyto textiles as well as advanced multifunctionalities.Therefore, synergies of new available bio-based building-blocks, polymer synthesis and (nano)materiaIs have been explored to develop new finishing agents able to provide water and oil repellence to fabrics, without using fluorine-containing chemicals.In this work two different chemistries to confer water- and oil-repellence to textiles have been studied. In research line 1, biobased polyurethane-ureas have been developed. Obtained waterborne polyurethane-urea dispersions (WPUD) show good mechanical and thermal properties and therefore were chosen to be coated onto fabrics byknife-coating. In this way we were able to coat one side ofthe fabrics with a continuous polyurethane-urea film, capable of drastically reducing the permeability of the textiles to water and thus conferring remarkable hydrostatic pressure values to the treated fabrics.Therefore, ease offilming ofthe obtained WPUD make them good candidates to substitute PTFE inner membranes in technical fabrics. In research line 2, new fluorine-free waterborne (co)polymethacrytates have been developed. These polymethacrytates offer excellent performance when applied to fabric bythe padding method, i.e., by total immersion ofthe fabric in the finishing liquor, squeezing at controlled speed and pressure, and subsequent drying and curing. Unlike research line 1, here the coatings obtained do not significantly increase the stiffness ofthe fabrics nor significantly reduce their air permeability. This is dueto the fact that the polymethacrytate creates a thin coating on the surface of each individual libre, giving rise to "jacketed libres" instead a continuous film on one ofthe fabric's faces. Thanks to this, highlyhydrophobic breathable fabrics with reasonablygood oleophobic properties againstfattytriglycerides have been achieved. Therefore, these polymethacrytates are good candidates to substitute side-chain perfluorinated polymers in fabric's outer !ayer by more sustainable fluorine-free alternatives. lt is important to highlight that ali the developments reported in this work are stable waterborne formulations able to be applied by standard procedures and facilities in large-scale texUle production, thus reducing its entry barrier to textile finishing industry. Finally, it is worth emphasizing the complementarity of the two developed lines of research, providing the textile sector with an open window to valid, sustainable and fluorine-free solutions to achieve high-performance DWOR finishes
  • VALENTI, SOFIA: Physical properties, relaxation dynamics and applications of polymer solid dispersions
    Author: VALENTI, SOFIA
    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: Temporary seizure
    Deposit date: 30/05/2022
    Reading date: 11/07/2022
    Reading time: 11:00
    Reading place: Sala Polivalent de l'Edifici A, planta baixa, Campus Diagonal-Besòs
    Thesis director: PUIGGALI BELLALTA, JORGE | MACOVEZ, ROBERTO
    Committee:
         PRESIDENT: AFFOUARD, FRÉDÉRIC
         SECRETARI: PÉREZ MADRIGAL, MARIA DEL MAR
         VOCAL: CANGIALOSI, DANIELE
    Thesis abstract: Polymers can have a wide range of application, thanks to the capacity of designing them to meet specific requirements (e.g. mechanical, thermal, optical or electrical). In particular, polymeric materials with high biocompatibility and degradability can be easily prepared, for applications in the biomedical fields as scaffolds for tissue regeneration or matrices for drug delivery. A large number of drugs, in fact, display low solubility and/or poor temporal dissolution profile in aqueous environments. A low solubility, and especially a poor temporal dissolution profile, hinder the bioavailability and thus the implementation of these drugs in pharmaceutical formulations. Besides chemical modification of the drug, also physical strategies are available to enhance bioavailability, such as particle size reduction or amorphization, as well as co-crystal formation or drug dispersion in an appropriate carrier. Amorphous drugs show more solubility and better dissolution profiles (and hence better bioavallability) than crystal phases, in some cases they can be compactad into tablets more effectively than polycrystalline powders, and beneficial effects of amorphous formulations have been reported also in vivo.The amorphous phase is, however, thermodynamically unstable against crystallization and crystalline drug forms dominate the pharmaceutical market for practical and economical reasons. Even so, many drugs with originally poor aqueous solubility have reached the drug development stage, only thanks to its formulation in amorphous phase. One of the ways to improve the dissolution profile of a low-solubility drug and enhance the metastability of its amorphous state, is dispersing it in a polymer excipient with higher water solubility. Such binary mixtures may also allow controlled drug release or even targeted delivery if the dispersion of the drug is carried out in polymers that are only swellable or water-insoluble. lf a polymer is mixed with an inorganic nanofiller, instead of a drug, then the mixture is usually called a polymer nanocomposite. The addition of nanofillers can drastically change and improve the properties of polymers even at low filler content.Nanocomposites can now commercially compete with traditional materials thanks to the great improvements that can be achieved on thermal endurance, flame retardance, liquid and gas impermeability, or targeted electric, electronic and optical properties. While the potential for industrial scale applications of nanocomposites is vast, current applications have been developing ata very slow pace. In many cases, the performance of the rnaterials did not meet the expectations and sorne unexpected drawbacks or flaws were found. Further development of nanocomposites can only be achieved by a specific study of each polymer-filler system, and requires a deep understanding of the interfacial effects between polymer and fillers.While a plethora of studies can be found on small molecules, polymer blends, and polymer solutions, asymmetric binary mixtures (dispersions) of small molecules in polymer matrices have been sornewhat less studied, probably dueto the fact that this type of sample is located at the frontier between molecular physics and chemistry and macromolecular physics, and techniques which are valid for both of them are needed to carry out a comprehensive researcti on these systems. This thesis focuses on binary systems composed by polyrners (macrornolecules) and srnall, organic molecules or inorganic fillers such as carbon nanotubes. We have studied experimentally several distinct molecules (chloramphenicol, diazepam, nordazepam, tetrazepam, curcumin and morniflumate), fillers (carbon nanotubes) and polymers (polylactide, poly(4- hydroxybutyrate), polyurethane anda poly(ester amide)). Different polymer compositions (enantiomeric pure, racemic, or polymer blends) and sample preparation methods, such as film casting and solution or melt-electrospinning, were examined.

DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS

  • CARDOSO DUARTE, AMANDA: Data and methods for a visual understanding of sign languages
    Author: CARDOSO DUARTE, AMANDA
    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: 24/05/2022
    Reading date: 27/06/2022
    Reading time: 16:00
    Reading place: ETSETB- D5-010 link videoconferència: https://meet.google.com/acd-dukb-ywq
    Thesis director: GIRÓ NIETO, XAVIER | TORRES VIÑALS, JORDI
    Committee:
         PRESIDENT: SMEATON, ALAN
         SECRETARI: SAYROL CLOLS, ELISA
         VOCAL NO PRESENCIAL: ROGEZ, GRÉGORY
    Thesis abstract: Signed languages are complete and natural languages used as the first or preferred mode of communication by millions of people worldwide. However, they, unfortunately, continue to be marginalized languages. Designing, building, and evaluating models that work on sign languages presents compelling research challenges and requires interdisciplinary and collaborative efforts. The recent advances in Machine Learning (ML) and Artificial Intelligence (AI) has the power to enable better accessibility to sign language users and narrow down the existing communication barrier between the Deaf community and non-sign language users. However, recent AI-powered technologies still do not account for sign language in their pipelines. This is mainly because sign languages are visual languages, that use manual and non-manual features to convey information, and do not have a standard written form. Thus, the goal of this thesis is to contribute to the development of new technologies that account for sign language by creating large-scale multimodal resources suitable for training modern data-hungry machine learning models and developing automatic systems that focus on computer vision tasks related to sign language that aims at learning better visual understanding of sign languages.Thus, in Part I, we introduce the How2Sign dataset, which is a large-scale collection of multimodal and multiview sign language videos in American Sign Language. In Part II, we contribute to the development of technologies that account for sign languages by presenting in Chapter 4 a framework called Spot-Align, based on sign spotting methods, to automatically annotate sign instances in continuous sign language. We further present the benefits of this framework and establish a baseline for the sign language recognition task on the How2Sign dataset. In addition to that, in Chapter 5 we benefit from the different annotations and modalities of the How2Sign to explore sign language video retrieval by learning cross-modal embeddings. Later in Chapter 6, we explore sign language video generation by applying Generative Adversarial Networks to the sign language domain and assess if and how well sign language users can understand automatically generated sign language videos by proposing an evaluation protocol based on How2Sign topics and English translation.
  • HERBERT, CHRISTOPH JOSEF: Advanced methods for earth observation data synergy for geophysical parameter retrieval
    Author: HERBERT, CHRISTOPH JOSEF
    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: 08/06/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: VALL-LLOSSERA FERRAN, MERCEDES MAGDALENA | CAMPS CARMONA, ADRIANO JOSE
    Committee:
         PRESIDENT: WICKERT, JENS
         SECRETARI: CORBELLA SANAHUJA, IGNASI
         VOCAL: LÓPEZ SÁNCHEZ, JUAN MANUEL
    Thesis abstract: The first part of the thesis focuses on the analysis of relevant factors to estimate the response time between satellite-based and in-situ soil moisture (SM) using a Dynamic Time Warping (DTW). DTW was applied to the SMOS L4 SM, and was compared to in-situ root-zone SM in the REMEDHUS network in Western Spain. The method was customized to control the evolution of time lag during wetting and drying conditions. Climate factors in combination with crop growing seasons were studied to reveal SM-related processes. The heterogeneity of land use was analyzed using high-resolution images of NDVI from Sentinel-2 to provide information about the level of spatial representativity of SMOS data to each in-situ station. The comparison of long-term precipitation records and potential evapotranspiration allowed estimation of SM seasons describing different SM conditions depending on climate and soil properties. The second part of the thesis focuses on data-driven methods for sea ice segmentation and parameter retrieval. A Bayesian framework is employed to segment sets of multi-source satellite data. The Bayesian unsupervised learning algorithm allows to investigate the `hidden link¿ between multiple data. The statistical properties are accounted for by a Gaussian Mixture Model, and the spatial interactions are reflected using Hidden Markov Random Fields. The algorithm segments spatial data into a number of classes, which are represented as a latent field in physical space and as clusters in feature space. In a first application, a two-step probabilistic approach based on Expectation-Maximization and the Bayesian segmentation algorithm was used to segment SAR images to discriminate surface water from sea ice types. Information on surface roughness is contained in the radar backscattering images which can be - in principle - used to detect melt ponds and to estimate high-resolution sea ice concentration (SIC). In a second study, the algorithm was applied to multi-incidence angle TB data from the SMOS L1C product to harness the its sensitivity to thin ice. The spatial patterns clearly discriminate well-determined areas of open water, old sea ice and a transition zone, which is sensitive to thin sea ice thickness (SIT) and SIC. In a third application, SMOS and the AMSR2 data are used to examine the joint effect of CIMR-like observations. The information contained in the low-frequency channels allows to reveal ranges of thin sea ice, and thicker ice can be determined from the relationship between the high-frequency channels and changing conditions as the sea ice ages. The proposed approach is suitable for merging large data sets and provides metrics for class analysis, and to make informed choices about integrating data from future missions into sea ice products. A regression neural network approach was investigated with the goal to infer SIT using TB data from the Flexible Microwave Payload 2 (FMPL-2) of the FSSCat mission. Two models - covering thin ice up to 0.6m and the full-range of SIT - were trained on Arctic data using ground truth data derived from the SMOS and Cryosat-2. This work demonstrates that moderate-cost CubeSat missions can provide valuable data for applications in Earth observation.

DOCTORAL DEGREE IN SUSTAINABILITY

  • BALTÀ SALVADOR, ROSÓ: L'experiència acadèmica i el benestar de l'estudiantat en situació de risc en estudis STEM
    Author: BALTÀ SALVADOR, ROSÓ
    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: 27/05/2022
    Reading date: 29/06/2022
    Reading time: 12:00
    Reading place: ETSECPPB, edifici C1, aula C1-002, Barcelona. UPC
    Thesis director: OLMEDO TORRE, NOELIA | PEÑA CARRERA, MARTA
    Committee:
         PRESIDENT: ESPINACH ORUS, FRANCISCO JAVIER
         SECRETARI: LUSA GARCIA, AMAIA
         VOCAL: CAMARERO FIGUEROLA, MARTA
    Thesis abstract: One of the main goals of the 2030 Agenda for sustainable development is to guarantee quality education for all students, especially the most vulnerable. Engineering studies are a key element in educating and training future generations in the design and development of innovative solutions that contribute to the achievement of the Sustainable Development Goals (SDGs). However, some situations may prevent the provision of quality education for all students. This research explores two of them: (1) students who are part of minority groups, specifically foreign-born students, and (2) learning during an emergency situation. As previous literature has shown, these are two threatening contexts involving multiple factors that can have a negative impact on students, affecting their performance and academic persistence. This thesis aims to provide a better understanding of the factors that intervene in engineering students' educational experience and well-being when they find themselves in these situations to determine how the elements studied can compromise their development and prevent them from benefiting from an equitable and quality education. The research is based on three analytical-descriptive studies, two of them using cross-sectional surveys and one of them using a longitudinal survey. The questionnaires were distributed to undergraduate engineering students at the Universitat Politècnica de Catalunya · BarcelonaTech (UPC). From the data collected, descriptive and inferential statistical methods were used to perform the analysis. The results showed that the risk situations analyzed do indeed have an impact on the well-being and academic experience of the students. Among other detrimental effects, it is worth highlighting the decrease in psychological well-being, such as in students' self-esteem and the feelings of worry, discouragement, discomfort, and vigilance. The situations analyzed also have a significant impact on their learning and academic development, to the point of leading students to drop out of their studies. To address the risks to which students are exposed and mitigate their negative affect, this thesis identifies good practices and recommendations that will help academic institutions develop appropriate support systems.
  • RAMIREZ AGUDELO, NANCY ANDREA: Nature-based solutions for waterfronts reconfigurations: Litoral Besòs, analysis of an urban sustainability transition in the Barcelona metropolitan area
    Author: RAMIREZ AGUDELO, NANCY 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 SUSTAINABILITY
    Department: University Research Institute for Sustainability Science and Technology (IS.UPC)
    Mode: Temporary seizure
    Deposit date: 03/06/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: ROCA BOSCH, ELISABETH | DE PABLO RIBAS, JOAN
    Committee:
         PRESIDENT: ROVIRA BOIXADERAS, MIGUEL ARCANGEL
         SECRETARI: MORATO FARRERAS, JORDI
         VOCAL NO PRESENCIAL: SULEIMAN, LINA
    Thesis abstract: Cities need to respond urgently to societal challenges, such as urbanization, changes in climate, and risk management. These challenges require innovative solutions in urban systems developed with citizens to provide multiple benefits and more inclusive living environments. Nature-based solutions (NBS) are currently attracting the interest of public policy and urban research for addressing these needs, considering the social, ecological, and technological dimensions with a territorial focus. NBS implementation is-an ongoing, broad and local change process that shifts different urban domains and generates impacts and benefits for all citizens. For example, NBS are used in waterfront reconfigurations as alternative practices to address water quality and quantity challenges, among other issues, while promoting ecosystem services and creating new green infrastructure.This thesis analyzes NBS implementation as a strategy (understood as processes, results, and impacts) to address water in peri-urban areas and produce transformative effects. The case study method and the concept of urban sustainability transitions as -fundamental, structural, and multidimensional change- are used for this purpose. The research develops a systematic literature review of NBS implementation experiences globally, which aided in identifying barriers and lessons learned, emphasizing communication and monitoring to facilitate actors¿ participation. Subsequently, a case study in the Barcelona metropolitan area is analyzed in-depth, the Litoral Besòs, through semi-structured interviews with local actors, user surveys, and participant observation in public participatory processes in urban planning. The case study has verified how the NBS implemented have favored transformative shifts of the Litoral Besòs.The NBS as a riverside park and constructed wetlands addressed water problems, enabling the development of reuse technologies, natural capital regeneration, and keeping resources in use, which ultimately is an advancement for a more sustainable urban water management. However, citizens (as frequent users) can play a more significant role in NBS management and scalability. Citizens¿ perceptions, through regular monitoring, could contribute to NBS management while increasing knowledge and awareness about the benefits and biotic management. In addition, by participating in the seafront redevelopment formulation, citizens exposed the need for mediation between the urban sustainability accounts (opposing, non-conflictual, and reinforcing), advocating a more socially just aim in this reconfiguration.The findings show how NBS promote physical changes and environmental improvements, such as multifunctionality and hybridization for place-based transitions. New cultural experiences and practices include citizenship as a direct beneficiary, user, and participant. This shift in multi-actor dynamics is an iterative process, requiring flexibility for long-term urban change. NBS have the potential to support the needed social-ecological-technological transition to urban sustainability. Therefore, NBS, as providers of adaptive capacities, must still overcome some constraints, which makes necessary to favor institutional shifts, more open-ended urban planning practices, and bottom-up management strategies. Finally, the NBS reframe urban issues by highlighting social and climate justice in alternative visions of the future, encouraging more inclusive and thus more resilient urban reconfigurations.Keywords: urban governance; social vulnerability; circular economy; place-based transition; multi-actor dynamics; urban experimentation; problem reframing; visioning importance; Besòs riverside park; Three Chimneys litoral front

DOCTORAL DEGREE IN THERMAL ENGINEERING

  • ÁLVAREZ FARRÉ, XAVIER: A hierarchical parallel implementation model for algebra-based CFD simulations on hybrid supercomputers
    Author: ÁLVAREZ FARRÉ, XAVIER
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN THERMAL ENGINEERING
    Department: Department of Heat Engines (MMT)
    Mode: Normal
    Deposit date: 16/05/2022
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: GOROBETS, ANDREY | OLIVA LLENA, ASENSIO
    Committee:
         PRESIDENT: PASCAU BENITO, ANTONIO
         SECRETARI: PEREZ SEGARRA, CARLOS DAVID
         VOCAL: MOULINEC, CHARLES
    Thesis abstract: Continuous enhancement in hardware technologies enables scientific computing to advance incessantly and reach further aims. Since the start of the global race for exascale high-performance computing (HPC), massively-parallel devices of various architectures have been incorporated into the newest supercomputers, leading to an increasing hybridization of HPC systems. In this context of accelerated innovation, software portability and efficiency become crucial.Traditionally, scientific computing software development is based on calculations in iterative stencil loops (ISL) over a discretized geometry¿the mesh. Despite being intuitive and versatile, the interdependency between algorithms and their computational implementations in stencil applications usually results in a large number of subroutines and introduces an inevitable complexity when it comes to portability and sustainability. An alternative is to break the interdependency between algorithm and implementation to cast the calculations into a minimalist set of kernels.The portable implementation model that is the object of this thesis is not restricted to a particular numerical method or problem. However, owing to the CTTC's long tradition in computational fluid dynamics (CFD) and without loss of generality, this work is targeted to solve transient CFD simulations. By casting discrete operators and mesh functions into (sparse) matrices and vectors, it is shown that all the calculations in a typical CFD algorithm boil down to the following basic linear algebra subroutines: the sparse matrix-vector product, the linear combination of vectors, and the dot product.The proposed formulation eases the deployment of scientific computing software in massively parallel hybrid computing systems and is demonstrated in the large-scale, direct numerical simulation of transient turbulent flows.

ERASMUS MUNDUS DOCTORAL DEGREE IN INFORMATION TECHNOLOGIES FOR BUSINESS INTELLIGENCE

  • HEWASINGHAGE, MODITHA LAKSHAN DHARMASIRI: Physical database design in document stores
    Author: HEWASINGHAGE, MODITHA LAKSHAN DHARMASIRI
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: ERASMUS MUNDUS DOCTORAL DEGREE IN INFORMATION TECHNOLOGIES FOR BUSINESS INTELLIGENCE
    Department: Department of Service and Information System Engineering (ESSI)
    Mode: Change of supervisor
    Deposit date: 04/04/2022
    Reading date: 12/07/2022
    Reading time: 09:00
    Reading place: FIB- Sala d'Actes Manuel Martí Recober - FIB
    Thesis director: ABELLO GAMAZO, ALBERTO | VARGA, JOVAN | ZIMANYI BORRAGEIROS, ESTEBAN
    Committee:
         PRESIDENT: WREMBEL, ROBERT
         SECRETARI: BADIA FLORENSA, ANTONIO
         VOCAL NO PRESENCIAL: ZISSIS, DIMITRIS
    Thesis abstract: NoSQL is an umbrella term used to classify alternate storage systems to the traditional Relational Database Management Systems (RDBMSs). Among these, Document stores have gained popularity mainly due to the semi-structured data storage model and the rich query capabilities. They encourage users to use a data-first approach as opposed to a design-first one. Database design on document stores is mainly carried out in a trial-and-error or ad-hoc rule-based manner instead of a formal process such asnormalization in an RDBMS. However, these approaches could easily lead to a non-optimal design resulting additional costs in the long run.This PhD thesis aims to provide a novel multi-criteria-based approach to database design in document stores. Most of such existing approaches are based on optimizing query performance. However, other factors include storage requirement and complexity of the stored documents specific to each use case. There is a large solution space of alternative designs due to the different combinationsof referencing and nesting of data. Thus, we believe multi-criteria optimization is ideal to solve this problem. To achieve this, weneed to address several issues that will enable us to apply multi-criteria optimization for the data design problem.First, we evaluate the impact of alternate storage representations of semi-structured data. There are multiple and equivalent ways tophysically represent semi-structured data, but there is a lack of evidence about the potential impact on space and query performance. Thus, we embark on the task of quantifying that precisely for document stores. We empirically compare multiple waysof representing semi-structured data, allowing us to derive a set of guidelines for efficient physical database design considering both JSON and relational options in the same palette.Then, we need a formal canonical model that can represent alternative designs. We propose a hypergraph-based approach for representing heterogeneous datastore designs. We extend and formalize an existing common programming interface to NoSQL systems as hypergraphs. We define design constraints and query transformation rules for representative data store types. Next, we propose a simple query rewriting algorithm and provide a prototype implementation together with storage statistics estimator.Next, we require a formal query cost model to estimate and evaluate query performance on alternative document store designs.Document stores use primitive approaches to query processing, such as relying on the end-user to specify the usage of indexes instead of a formal cost model. But we require a reliable approach to compare alternative designs on how they perform on a specific query. For this, we define a generic storage and query cost model based on disk access and memory allocation. As all documentstores carry out data operations in memory, we first estimate the memory usage by considering the characteristics of the storeddocuments, their access patterns, and memory management algorithms. Then, using this estimation and metadata storage size, we introduce a cost model for random access queries. We validate our work on two well-known document store implementations.The results show that the memory usage estimates have an average precision of 91% and predicted costs are highly correlated to the actual execution times. During this work, we also managed to suggest several improvements to document stores.Finally, we implement the automated database design solution using multi-criteria optimization. We introduce an algebra of transformations that can systematically modify a design of our canonical representation. Then, using them, we implement a local search algorithm driven by a loss function that can propose near-optimal designs with high probability. We compare our prototype against an existing document store data design solution. Our proposed designs have better performance and are more compact with less redundancy.

NAUTICAL ENGINEERING, MARINE AND NAVAL RADIOELECTRONICS

  • HENRIQUEZ LARRAZABAL, RICARDO DANIEL: Digital Transformation and Business Models in Maritime Trade Supply Chains
    Author: HENRIQUEZ LARRAZABAL, RICARDO DANIEL
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: NAUTICAL ENGINEERING, MARINE AND NAVAL RADIOELECTRONICS
    Department: Department of Nautical Sciences and Engineering (CEN)
    Mode: Normal
    Deposit date: 07/06/2022
    Reading date: 03/08/2022
    Reading time: pending
    Reading place: pending
    Thesis director: MARTINEZ DE OSÉS, FRANCISCO JAVIER | MARTÍNEZ MARÍN, JESÚS EZEQUIEL
    Committee:
         PRESIDENT: SALAMA BENAZAR, ROSANA
         SECRETARI: RODRIGO DE LARRUCEA, JAIME
         VOCAL: FUENTES MOLINA, IVETTE
    Thesis abstract: This doctoral research explores the inter-relationship between the contemporary phenomena known as digital transformation, and the adoption of certain business models in the context of the maritime trade supply chain industry. Most specifically, it enquires the impact that the former might have on the latter. The question¿s relevance is twofold. On the one hand, the pace of both technological and business innovation has accelerated during the last 15 years, especially for certain industries. On the other hand, while there has been some degree of innovation in maritime trade supply chains, the industry lags behind other economic sectors; still working with technologies, business models and processes that predate the contemporary globalization era. Thus, understanding how and why the adoption of certain technologies might generate new ways of creating, delivering and capturing value in maritime trade supply chains, becomes a significant undertaking from both a theoretical and practical perspective.To address this enquiry, we have conducted four separate studies in this dissertation. In Chapter 2, we conduct a theoretical synthesis in order to provide a general theoretical background for the research conducted in the subsequent chapters. Chapter 3 is mainly concerned with physical flows. We investigate what impact does the adoption of Industry 4.0 technologies by seaports might have on their business models. To define these, we refer to the classification of seaports across a generational ladder: from 1st generation to 5th generation ports; referring as well to the novel construct of Port 4.0, and the commonly used ¿smart port¿ term. In Chapter 4 we turn to information flows. Most specifically, we explore the influence that distributed ledger technology (DLT) ¿most commonly known as blockchain¿ might have on the adoption of sustainable business models in the shipping industry. Chapter 5 focus on financial flows. It presents a design science study on a problem known as the trade finance gap; understood as the difference between the total supply of and demand for trade finance in international trade on a global level. The main question addressed is how to design a new business model that would address the causes behind the said trade finance gap.To conclude, this dissertation explores how digital transformation affects or impacts business models in maritime trade supply chains. It does so, by conducting studies on different contexts, each of them primarily focused on either physical, information or financial flows. From a theoretical perspective, the dissertation provides insights on the interplay between the three flows in maritime trade; with a special focus on how digital transformation, by affecting this interplay, drives or contributes to the adoption of new business models. Most specifically, Industry 4.0 technologies like IoT or DLT improve the way information flows interact with physical and financial flows. From a practical/managerial perspective, the research provides useful insights for business executives and policy makers, on how digital transformation should be faced at the strategic, tactical and operational level. By understanding how new technologies affect the ways in which value is created, delivered and captured, decision makers can design better business models, increasing competitiveness; or implement more adequate policies and strategies. Most importantly, the dissertation aims to serve as a source of ideas for those entrepreneurs who, through their startups, will design and develop innovative use cases and business models for the maritime industry.
  • UYA JUNCADELLA, AFRICA: Vessel Traffic Services, towards e-Navigation. The role of Oceanic VTS in Global Maritime Surveillance
    Author: UYA JUNCADELLA, AFRICA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: NAUTICAL ENGINEERING, MARINE AND NAVAL RADIOELECTRONICS
    Department: Department of Nautical Sciences and Engineering (CEN)
    Mode: Normal
    Deposit date: 25/04/2022
    Reading date: 06/07/2022
    Reading time: 12:00
    Reading place: FNB- Sala Juntes Facultat Nàutica UPC
    Thesis director: MARTINEZ DE OSÉS, FRANCISCO JAVIER
    Committee:
         PRESIDENT: CASTELLS SANABRA, MARCEL·LA
         SECRETARI: MARTÍNEZ MARÍN, JESÚS EZEQUIEL
         VOCAL: CUETO ANCELA, JOSÉ LUIS
    Thesis abstract: This thesis presents the study and analysis of the Vessel Traffic Services (VTS), from its origins to the present, with further evaluation of future trends. Examining the current trend in terms of technologies that are being applied in the maritime sector, the dissertation focuses on the future to draw a new paradigm. This envisages a scenario at a planetary level, following a single global traffic management system, which would create a model of the global VTS Operator. A new assignment is proposed, according to this third dimension, with Port VTS being the first level, the Coastal VTS second, and with the Oceanic VTS projected into the future, which is a substantial proposal. The foundation is based on EU projects, the most ambitious of which, currently underway, being Sea Traffic Management (STM), with a scope greater than Europe, and also on IALA VTS and ENAV Committee Working Groups, concerning the future of VTS. The study includes the reference documentation from the IMO, in resolution format, and that of the IALA, under Standards, Recommendations and Guidelines. From the first recognition of the IMO to the present, the guidelines for VTS have undergone three updates, which are analysed and compared. VTS are considered aids to navigation, AtoN, which contribute to safety of life at sea, safety and efficiency of navigation and protection of the marine environment, and are linked to ship traffic activity. Both their attributions and the implementation of VTS centres have increased over time. In addition to this, the evolution of the tools used by the VTS is examined, from its earliest stages with only two pieces of equipment, the VHF radio, and the radar. The VTS system began by looking at the air traffic model but, later, the maritime nature created necessary differentiation in terms of management and procedures. Digital technologies applied to the maritime sector take air traffic controllers¿ models as a reference, and the current VTS Operator profession will acquire analogies, such as sharing route plans and checking digital inputs. This highly specialised profession is facing the challenges of satellite technology, global interconnection, and the arrival of Maritime Autonomous Surface Ships (MASS). New technologies bring the possibility of sharing information and controlling traffic on a global scale, beyond the territorial sea, and this scenario will make standardisation increasingly necessary throughout the maritime sector. The identification of various models of traffic management, examination of systems operating specifically in the Spanish State and reflection on the diversity that prevails is also included. Based on fieldwork, the thesis determines that the future complexities that will emerge from maritime traffic will require exhaustive risk assessment and analysis. The challenges to be faced involve maritime communications via satellite and digital technology, in the context of `e-Navigation¿ (coined by the IMO), which will provide emerging tools, such as VDES (next generation of AIS), and a planetary-scale information exchange framework for VTS worldwide.

Last update: 24/06/2022 04:45:26.