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Public display of deposited theses

Presentació d'al·legacions a una tesi doctoral en el termini d'exposició pública

In accordance with the Academic Regulations for Doctoral Studies, doctors may request access to a doctoral thesis in deposit for consultation and, if there are, to send to the Permanent Commission of the Doctoral School the observations and allegations that they consider opportune on the content.

 

DOCTORAL DEGREE IN BIOMEDICAL ENGINEERING

  • MATEU SANZ, MIGUEL: Cold Plasma-Derived Oxidative Stress for Osteosarcoma Therapy
    Author: MATEU SANZ, MIGUEL
    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: (CEM)
    Mode: Article-based thesis
    Deposit date: 16/05/2022
    Deposit END date: 27/05/2022
    Thesis director: CANAL BARNILS, CRISTINA | TORNIN CAVIELLES, JUAN
    Committee:
         PRESIDENT: MORA GRAUPERA, JAUME
         SECRETARI: MAS MORUNO, CARLOS
         VOCAL: PRIVAT MALDONADO, ANGELA
    Thesis abstract: This thesis is framed in the ERC Starting Grant Project ¿Atmospheric Pressure plAsma meets biomaterials for bone Cancer HEaling (APACHE)¿. The APACHE Project aims at evaluating plasma technology as therapy against bone cancer. At present, bone sarcomas are one of the cancers with worst prognosis and most difficult treatment. Among the different kinds of bone sarcomas, osteosarcoma (OS) has the highest incidence. Current therapies for OS, based on surgery, chemotherapy and radiotherapy, are not completely effective and present undesirable adverse effects. Cold atmospheric plasmas (CAP), consisting in highly reactive ionized gases, have been demonstrated to induce lethal effects in different kinds of cancers without damaging surrounding tissues. CAP are a source of a high amount of reactive oxygen and nitrogen species (RONS) that affect cancer cells by complex biochemical processes. These RONS are thought to be the main responsible of the effects of plasma in cancer cells, that are significantly more sensitive to them than non- malignant cells. These RONS can induce from cell cycle arrest at low plasma doses, to apoptosis at higher doses, as has been described for other cancers in in vitro and in vivo models. In spite of the knowledge of plasma effects in distinct types of cancer, the available studies about mechanisms involved in anti-tumor effect in OS are still limited. CAP can be used to produce RONS in liquids, known as plasma-conditioned liquids (PCL), that have been demonstrated to produce comparable effects to direct CAP treatment. Accordingly, the aim of this thesis is to investigate the application of this new therapy for OS by the use of PCL as a potential therapy for local treatment. For this purpose, in this PhD Thesis in Chapter 1 first the generation of RONS by CAP in plasma-conditioned culture media (PCM) is investigated and related with the cytotoxic effects induced in OS cells and non-malignant bone precursors. In Chapter 2, the cytotoxic effects of the PCL constituted by Ringer¿s saline are evaluated at selective conditions in different OS cell lines and non-malignant bone precursors as well as in ex vivo mouse tumor tissues. In Chapter 3, the existing knowledge about CAP in OS and current challenges to overcome are reviewed and discussed. Finally, in Chapter 4 the effect of PCL is studied in different OS cultures, in 3D bioengineered tumor models and in an in vivo mouse models, focusing in the evaluation of antioxidant defenses, molecular pathways and the impact on OS subpopulations with stem properties. As main conclusion, we can confirm that PCL have shown efficient agents against OS through to the production of long-lived RONS, which determine the selective cytotoxic effect in OS and non-malignant cells. PCL are able to trigger anti-tumorigenic signaling and apoptotic cell death in OS cells by the induction of oxidative stress. However, insufficient levels of RONS may induce pro-survival factors of stress response in vitro and to be pro-tumorigenic in vivo. Specifically, cancer cells with elevated antioxidant ability, like cancer stem cells, display increased resistance to PCL. We have demonstrated that targeting the STAT3 transcription factor, we can inhibit the expression of antioxidant defenses and the cytotoxic effect of PCL can be enhanced, inducing cell death in OS PCL-resistant and cancer stem cells in vitro and effectively reducing tumor volume in vivo.

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
    Deposit END date: 08/06/2022
    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 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
    Deposit END date: 08/06/2022
    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.
  • 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
    Deposit END date: 31/05/2022
    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 ENVIRONMENTAL ENGINEERING

  • JOU CLAUS, SÒNIA: Diferent approaches to improve groundwater resources management: submarine groundwater discharge and managed aquifer recharge
    Author: JOU CLAUS, SÒNIA
    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: Normal
    Deposit date: 16/05/2022
    Deposit END date: 27/05/2022
    Thesis director: FOLCH SANCHO, ALBERT | RODRIGUEZ ESCALES, PAULA FELICIDAD
    Committee:
         PRESIDENT: MAS PLA, JOSEP
         SECRETARI: SANCHEZ VILA, FRANCISCO JAVIER
         VOCAL: PEDRETTI, DANIELE
    Thesis abstract: Global change is expected to affect significantly the global hydrological behavior, changing mean annual precipitation patterns, increasing length of drought periods, rising evaporation and atmospheric water vapor and decreasing ice cover. All these changes imply significant challenges to find solutions that could contribute to mitigate the effects of global change in groundwater quality and its effect on the environment. In this context, the application of remote sensing in groundwater studies represent a useful technique to complement the information obtained with the traditional methods in hydrogeological studies used for the characterization and quantification of water resources. In the same way, Managed Aquifer Recharge (MAR) represents a feasible solution to deal with future water management challenges promoting the storage of available water in aquifers and improving the recharged water quality. The present dissertation is focused on improving groundwater resources management in two different ways. First, by using remote sensing tools for the characterization of coastal areas and second, by using reactive barriers to improve degradation of contaminants of emerging concern in the context of managed aquifer recharge coupled to the outflow of a waste water treatment plant.Firstly, we evaluate the usefulness of using freely available thermal infrared (TIR) imagery of the Landsat 8 as an exploratory tool for identifying SGD springs worldwide. The use of satellite thermal data as a technique for identifying SGD springs in sea water is based on the identification of thermally anomalous plumes obtained from the thermal contrasts between groundwater and sea surface water. The main goal of this first part of the conducted research is to demonstrate the significant usefulness of Landsat 8 TIR images as an exploratory tool for identifying SGD springs (karts areas) worldwide and discuss the main limiting factors of using this technique in SGD studies. Results show that satellite TIR remote sensing is a useful method for identifying coastal springs in karst aquifers both locally and regionally. However, there are some limiting factors that need to be considered as, technical limitations, geological and hydrogeological characteristics of the studied area, environmental and marine conditions, and coastal geomorphology. Secondly, we present the potential use of satellite chlorophyll (Chl-a) data as a low-cost tool for mapping the spatial and temporal evolution of the ecological influence of SGD in coastal habitats. To distinguish high Chl-a concentrations derived from SGD to those derived from other potential sources, a clustered analysis were applied to Landsat 8 satellite Chl-a data. Results show that satellite Chl-a data offers the possibility to identify and constrain areas where SGD inputs have increased primary productivity and calculate the Chl-a concentration gradient along time induced by SGD. Finally, we investigate the fate of selected UV filters (UVFs) in two MAR systems; one supplemented with a reactive barrier containing clay and vegetable compost, and the other as a reference system. We monitor benzophenone-3 (BP-3) and its transformation products (TPs) (benzophenone-1 (BP-1), 4,4'-dihydroxybenzophenone (4-DHB), 4-hydroxybenzophenone (4-HB) and 2,2'-dihydroxy-4-methoxybenzophenone (DHMB)), benzophenone-4 (BP-4) and avobenzone (AVO) at all involved compartments (water, soil, and biofilm), before and after modifying redox conditions through a pulse of lithium acetate. Results show that the implementation of a reactive barrier in MAR systems improve substantially the degradation extent of UVF, especially of BP-3 and its TPs. The present dissertation contributes to improve groundwater resources management throughout new methodological and technical approaches to deal with the new challenges of today¿s society.

DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING

  • 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
    Deposit END date: 07/06/2022
    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 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
    Deposit END date: 31/05/2022
    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.

DOCTORAL DEGREE IN PHOTONICS

  • 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
    Deposit END date: 08/06/2022
    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
    Deposit END date: 03/06/2022
    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.

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
    Deposit END date: 07/06/2022
    Thesis director: GIRÓ NIETO, XAVIER | TORRES VIÑALS, JORDI
    Committee:
         PRESIDENT: SMEATON, ALAN
         SECRETARI: SAYROL CLOLS, ELISA
         VOCAL: 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.

DOCTORAL DEGREE IN THEORY AND HISTORY OF ARCHITECTURE

  • ARRIBAS SANCHEZ, CRISTINA: Metapostales: la imagen moderna de España a través de las tarjetas postales en el boom desarrollista
    Author: ARRIBAS SANCHEZ, CRISTINA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN THEORY AND HISTORY OF ARCHITECTURE
    Department: (THATC)
    Mode: Normal
    Deposit date: 17/05/2022
    Deposit END date: 30/05/2022
    Thesis director: LAHUERTA ALSINA, JUAN JOSE | PIZZA DE NANNO, ANTONIO
    Committee:
         PRESIDENT: DÍAZ CUYÁS, JOSÉ MARÍA
         SECRETARI: MARÍN VEGA, CELIA
         VOCAL: COSTA VILA, JORGE
    Thesis abstract: In the introduction to the first chapter of her book On Photography, specifically in the well-known text on the fragment of the film Les Carabiniers (1963) by Jean-Luc Godard, Susan Sontag refers to postcards with a certain contemptuous tone within the world of photography. In the text, Sontag refers to the moment when the soldiers return home loaded with postcards, opening our eyes to see photography not as a means of capturing the surroundings, but as a way in which the photo trade takes advantage of the medium to objectify and trivialize those views that, transformed into postcards, can be commercially profitable.Precisely that position of the postcard, apparently only commercial, but also naive, is the starting point of this thesis, which has set itself the objective of placing the postcard on the level and pedestal that, in my opinion, it deserves.The thesis is structured in three chapters, and is materialized in three tourist guides that illustrate, in turn, four albums of postcards.1. The postcardLooking at it from the first decades of the 21st century, we cannot even imagine the great importance and transcendence that a postcard could have had at the beginning of the sixties of the last century, without going any further back. Its documentary value, as well as the visual and communicative information it provided, is unimaginable today. The first chapter shows a journey through the meaning, importance, typologies, historical framework, social uses and transcendence of the postcard-object. 2. ¿Greetings from USA¿ / Saludos desde España.The second chapter focuses on showing the backward situation of Spain, mainly its image, at the end of the fifties, and its evolution throughout the developmentalist stage, as well as the American reality of the same period, which will be referential and decisive in the modernization of our country. This chapter traces a journey along the prototypes of modernity through its images, the new modern monuments, fruit of capitalism and consumption. The image of the United States was disseminated through the country¿s cultural and entertainment industries, including of course ¿although it has not been taken too seriously up to date ¿ postcards. Spain, like the rest of the Western European countries, desired a more comfortable life, with more free time for leisure and consumption, an attitude that provoked, at least in Spain, a drift towards Americanization. 3. Visual analysis of postcards.The third and last chapter focuses on the visual analysis of the front of the postcard: the content, the image, the photography, the graphics, the intentions of its designs, its manipulation, the trend and the insistence on certain patterns. The underdevelopment of the country, and that almost unbridled desire for openness, will multiply and exaggerate a carefree and optimistic image. Precisely the paradoxical duality between the identity of the hitherto Spanish and its modernization is what will result in an image full of disconnections, which originates an almost new graphic genre dominated by Spanishness and the most pop kitsch. It is important to emphasize the generalized and, above all, massive aspect that the postcard represents in the diffusion of the country¿s image: hundreds, thousands, hundreds of thousands of images are printed and sent, recreating with the same visual ¿tics¿ the Spanish reality of the moment.

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
    Deposit END date: 27/05/2022
    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.
  • MOROZOVA, NINA: Development of CFD-based multi-fidelity surrogate models for indoor environmental applications
    Author: MOROZOVA, NINA
    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: 25/05/2022
    Deposit END date: 08/06/2022
    Thesis director: OLIVA LLENA, ASENSIO | TRIAS MIQUEL, FRANCESC XAVIER
    Committee:
         PRESIDENT: SERGENT, ANNE
         SECRETARI: RIGOLA SERRANO, JOAQUIM
         VOCAL: CARRILHO DE GRAÇA, GUILHERME
    Thesis abstract: This thesis presents a methodology for CFD-based multi-fidelity surrogate models for indoor environmental applications. The main idea of this work is to develop a model that has accuracy comparable to CFD simulations but at a considerably lower computational cost. It can perform real-time or faster than real-time simulations of indoor environments using ordinary office computers. This work can be divided into three main parts. In the first part, a rigorous analysis of the feasibility of affordable high-fidelity CFD simulations for indoor environment design and control is carried out. In this chapter, we analyze two representative test cases, which imitate common indoor airflow configurations, on a wide range of different turbulence models and discretization methods to meet the requirements for the computational cost, run-time, and accuracy. We apply the knowledge on the growth in computational power and advances in numerical algorithms in order to analyze the possibility of performing accurate yet affordable CFD simulations on ordinary office computers. The no-model and LES with staggered discretizations studied turbulence models show the best performance. We conclude that high-fidelity CFD simulations on office computers are too slow to be used as a primary tool for indoor environment design and control. Taking into account different laws of computer growth prediction, we estimate the feasibility of high-fidelity CFD on office computers for these applications for the next decades. The second part of this thesis is dedicated to developing a surrogate data-driven model to predict comfort-related flow parameters in a ventilated room. This chapter uses a previously tested ventilated cavity with a heated floor case. The developed surrogate model predicts a set of comfort-related flow parameters, such as the average Nusselt number on the hot wall, jet separation point, average kinetic energy, average enstrophy, and average temperature, which were also comprehensively studied in the previous part of the thesis. The developed surrogate model is based on the gradient boosting regression, chosen due to its accurate performance among four tested machine learning methods. The model inputs are the temperature and velocity values in different locations, which act as a surrogate of the sensor readings. The locations and the number of these sensors were determined by minimizing the prediction error. This model does not require the repetition of CFD simulations to be applied since the structure of the input data imitates sensor readings. Furthermore, the low computational cost of model execution and good accuracy makes it an effective alternative to CFD for applications where rapid predictions of complex flow configurations are required, such as model predictive control. The third part of the thesis is an extension of the surrogate model developed in the second part. In this chapter, we implement a multi-fidelity approach to reduce the computational cost of the training dataset generation. The developed surrogate model is based on Gaussian process regression (GPR), a machine learning approach capable of handling multi-fidelity data. The variable fidelity dataset is constructed using coarse- and fine-grid CFD data with the LES turbulence model. We test three multi-fidelity approaches: GPR trained on both high- and low-fidelity data without distinction, GPR with linear correction, and multi-fidelity GPR or co-cringing. The computational cost and accuracy of these approaches are compared with GPRs based only on high- or low-fidelity data. All of the tested multi-fidelity approaches successfully reduce the computational cost of dataset generation compared to high-fidelity GPR while maintaining the required level of accuracy. The co-cringing approach demonstrates the best trade-off between computational cost and accuracy.

Last update: 25/05/2022 04:30:20.