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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 APPLIED MATHEMATICS

  • BELDA FERRÍN, GUILLEM: Conformal n-dimensional bisection for local refinement of unstructured simplicial meshes
    Author: BELDA FERRÍN, GUILLEM
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN APPLIED MATHEMATICS
    Department: (DECA)
    Mode: Normal
    Deposit date: 14/09/2022
    Deposit END date: 28/09/2022
    Thesis director: ROCA NAVARRO, FRANCISCO JAVIER | RUIZ GIRONÉS, ELOI
    Committee:
         PRESIDENT: LEDOUX, FRANK
         SECRETARI: SARRATE RAMOS, JOSE
         VOCAL: CUETO FELGUEROSO, LUIS
    Thesis abstract: In n-dimensional adaptive applications, conformal simplicial meshes must be locally modified. One systematic local modification is to bisect the prescribed simplices while surrounding simplices are bisected to ensure conformity. Although there are many conformal bisection strategies, practitioners prefer the method known as the newest vertex bisection. This method guarantees key advantages for adaptivity whenever the mesh has a structure called reflectivity. Unfortunately, it is not known (i) how to extract a reflection structure from any unstructured conformal mesh for three or more dimensions. Fortunately, a conformal bisection method is suitable for adaptivity if it almost fulfills the newest vertex bisection advantages. These advantages are almost met by an existent multi-stage strategy in three dimensions. However, it is not known (ii) how to perform multi-stage bisection for more than three dimensions. This thesis aims to demonstrate that n-dimensional conformal bisection is possible for local refinement of unstructured conformal meshes. To this end, it proposes the following contributions. First, it proposes the first 4-dimensional two-stage method, showing that multi-stage bisection is possible beyond three dimensions. Second, following this possibility, the thesis proposes the first n-dimensional multi-stage method, and thus, it answers question (ii). Third, it guarantees the first 3-dimensional method that features the newest vertex bisection advantages, showing that these advantages are possible beyond two dimensions. Fourth, extending this possibility, the thesis guarantees the first n-dimensional marking method that extracts a reflection structure from any unstructured conformal mesh, and thus, it answers question (i). This answer proves that local refinement with the newest vertex bisection is possible in any dimension. Fifth, this thesis shows that the proposed multi-stage method almost fulfills the advantages of the newest vertex bisection. Finally, to visualize four-dimensional meshes, it proposes a simple tool to slice pentatopic meshes. In conclusion, this thesis demonstrates that conformal bisection is possible for local refinement in two or more dimensions. To this end, it proposes two novel methods for unstructured conformal meshes, methods that will enable adaptive applications on n-dimensional complex geometry.

DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION

  • PADILLA MAGAÑA, JESUS FERNANDO: A Virtual Environment to evaluate and predict recovery of Human hand motion Post-stroke
    Author: PADILLA MAGAÑA, JESUS FERNANDO
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION
    Department: Department of Mechanical Engineering (EM)
    Mode: Normal
    Deposit date: 23/09/2022
    Deposit END date: 07/10/2022
    Thesis director: PEÑA PITARCH, ESTEBAN | TICÓ FALGUERA, MARIA NEUS
    Committee:
         PRESIDENT: REYES POZO, GUILLERMO
         SECRETARI: AL OMAR MESNAOUI, ANAS
         VOCAL: UNYÓ SALLENT, CARME
    Thesis abstract: The Action Research Arm Test (ARAT) is a measurement tool to assess post-stroke upper extremities motor function. However, ARAT scoring can be subjective and limited only to determining performance quality. Therefore, in this thesis, we presented a novelty hand motion system to improve the evaluation with the ARAT. The hand motion system is composed of a data glove CyberGlove II®, a Finger force sensing module, and a Graphical User Interface (GUI). In this thesis, three studies were conducted to evaluate whether the hand motion system improved the assessment with the ARAT. Firstly, in Chapter 4, we performed an analysis on healthy subjects using the hand motion system during the performance of the ARAT. We determined the fingertip force and the flexion angles of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of the fingers (index, middle, ring, and little) and carpometacarpal (CMC), MCP, and interphalangeal (IP) for the thumb. The results showed that the flexion angles and the finger force depend on the object size and the type of grasp used (power, grip, or pinch). In addition, an important database of the range of motion of the finger joints and finger forces was obtained. Secondly, Chapter 5 evaluated post-stroke patients with right (RH) and left (LH) hemiparesis to identify joint impairments and compensatory grasping strategies. For this purpose, an experimental study was carried out with 12 patients six months after a stroke with a global ARAT score = 10. The range of motion (ROM) of the finger joints in stroke patients was compared with the data obtained in Chapter 4. Stroke patients with LH and RH showed significantly lower flexion angles in the MCP joints of the Index and Middle fingers than the Control group. However, RH patients showed larger flexion angles in the PIP joints of the Index, Middle, Ring, and Little fingers. In contrast, LH patients showed larger flexion angles in the PIP joints of the Middle and Little fingers. Therefore, the results showed that RH and LH patients used compensatory strategies involving increased flexion at the PIP joints for decreased flexion in the MCP joints. In addition, the hand motion system allows the detection of finger joint impairments in stroke patients that are not visible from ARAT scores. Finally, in Chapter 6, we developed classification models to predict whether activities with similar ARAT scores were performed by a healthy subject or by a subject with stroke. For this purpose, we used three classification algorithms: Support Vector Machine (SVM), Random Forest (RF), and K-N Neighbors (KNN). The results showed that the SVM classifier had the best performance, with a precision of 98.3% and an accuracy of 94.5 %. However, the dataset showed class imbalance and the classification models presented a low recall, especially in the stroke class. Therefore, we implemented class balance using the technique Borderline-SMOTE (BSM). After data balancing, the models showed a significantly higher accuracy, recall, f1-score, and AUC. The SVM classifier showed a higher performance with a precision of 98% and a recall of 97.5% after data balancing. Hence, the results showed that classification models based on human hand motion features combined with BSM achieve higher performance.Therefore, we conclude that integrating the hand motion system during the performance of the ARAT allows for a quantitative, accurate, and sensitive assessment. Furthermore, the proposed method is of clinical relevance as it will help health care professionals to create more specific and effective rehabilitation programs for functional recovery of the hand in patients with stroke and other chronic diseases.Keywords: finger joints; finger force; ARAT; stroke; CyberGlove II; machine learning; hand; rehabilitation
  • WANG, BIN: Modelling and Vibration Control for a Submerged Piezoelectric Cantilever Beam
    Author: WANG, BIN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION
    Department: Institute of Robotics and Industrial Informatics (IRI)
    Mode: Temporary seizure
    Deposit date: 19/09/2022
    Deposit END date: 03/10/2022
    Thesis director: COSTA CASTELLO, RAMON | NA, JING
    Committee:
         PRESIDENT: DORMIDO BENCOMO, SEBASTIÁN
         SECRETARI: BATLLE ARNAU, CARLES
         VOCAL: HE, WEI
    Thesis abstract: In this thesis, the dynamic model for the piezoelectric cantilever beam is build by using partial differential equation (PDE). To facilitate the parameter estimation procedure and the controller design, a simplified control-oriented ordinary differential equation (ODE)-based model is constructed. Adaptive parameter estimation strategies are developed for the system with the first mode and the system with multi-modes respectively. In order to suppress the vibration of the beam, an unknown dynamics estimator (UDE)-based controller is introduced for the beam. To further take into account the unknown parameters, adaptive control is proposed which can online update the parameters. The main contributions of the thesis can be summarized as follows:1. Development of the PDE-based model and the ODE-based model for the submerged piezoelectric cantilever beam. The system is described by both the PDE-based model and ODE-based model. The motion equation of the cantilever beam is build with the help of Hamilton¿s principle. The piezoelectric actuator model is included in the derived PDE and the deflection-strain relationship is presented for the purpose of experimental validation. To make it convenient for parameter estimation, Galerkin method is adopted to convert the PDE to ODE. 2. Adaptive parameter estimation strategy design for the beam with one mode. A new adaptive parameter estimation framework is proposed to online estimate unknown system parameters considering the first vibration mode. To obtain the system states, the Levant exact differentiator via sliding mode technique is constructed. Instead of using the observer/predictor error as in the classical parameter estimation methods, a novel adaptive law which is driven by the parameter estimation error is proposed. 3. Adaptive parameter estimation for the beam with multi-modes by using input and output. In order to cope with multiple vibration modes of the beam, a novel parameter estimation strategy is formulated to identify the beam system. A novel adaptive law is introduced to estimate the unknown system parameters in real time. Specifically, a time-varying gain is designed to handle the effects of regressor to enhance convergence performance and simplify the tuning of learning gains. 4. Development of the UDE-based vibration control for the beam. An estimator based vibration control strategy is introduced to both suppress the vibration and estimate the unknown system dynamics. Different to the function approximation based methods, the proposed control has a simple structure which is more realistic to implement in practice. In the proposed estimator, only one parameter need to be tuned depends on the bandwidth of the filter. The estimated unknown dynamics is compensated into the controller and thus makes the system more robust to unknown external disturbances. The stability and convergence properties of the proposed control is proved by using Lyapunov theory.5. Adaptive control design for the beam. To suppress the vibration of the beam with unknown system parameters, an adaptive control is proposed. By using the parameter estimation error based adaptive law, the unknown system parameters can be online updated. To suppress the vibration of the beam, the adaptive controller is designed and the stability is proved.

DOCTORAL DEGREE IN COMPUTATIONAL AND APPLIED PHYSICS

  • KVASHIN, NIKOLAI: Atomistic study of slip transfer in BCC metals
    Author: KVASHIN, NIKOLAI
    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: 22/09/2022
    Deposit END date: 06/10/2022
    Thesis director: ANENTO MORENO, NAPOLEON | TERENTYEV, DMITRY
    Committee:
         PRESIDENT: MALERBA, LORENZO
         SECRETARI: CATURLA TEROL, MARÍA JOSÉ
         VOCAL NO PRESENCIAL: HARDOUIN DUPARC, OLIVIER
    Thesis abstract: The mechanical properties of the structural materials that are polycrystalline in nature are determined by a variety of physical processes taking place at different time and spatial scales. In these processes, bulk dislocations and grain boundaries (GB) play a significant role. Plastic deformation in these materials is mainly related to dislocation mobility, so the interaction of these defects with other pre-existing defects, such as GB, is a key factor explaining the evolution of properties over time. There are many possible types of GBs, and the behavior of one particular GB interacting with dislocations cannot be predicted and, therefore, must be analyzed individually. Macroscopically, these reac60ns are classified as absorption, transmission or refiecion of islocations. The connection of these reactions with the structure of the CBs, as wetl as with enernal parameters (stress, temperature, etc.) is the purpose of this study.The aim of the work is to predict tie result of the interacton of slip bands with CBs based on the multiscale modeling approach. This work presents a report on tie transferability of dislocations through CBs and on fre role of intrinsic defects at GBs. The main objective of this PhD research is to investigate the role of the GB atomic structure in interaction of GB with dislocations in order to be able to proxide a set of interacåon rules that can be easilytransferred to models dealing with higher time and spatial scales, for example, dislocation dynamics or the finite element method. To study the mechanisms of interaction of dislocation with GB, approach to the atomic level is required, for this reason, the molecular dynamics (MD) modeling method was chosen.This work presents the results of MD modeling conducted to studythe mechanisms of interaction between dislocations and symmetric tilt GBs, since they represent a significant number of interfaces present in real materials. For each GB under consideration, an analysis of the results was carried out, being the output a description of the dependence of the reaction type on temperature and applied stress. The obtained results are used as input data for the second stage of the work, which includes the e)Qansion of the simulation box to three-dimensional modeling to studythe interacton of GB defects with irradiation defects at the interface.As a result of the work, a number of new 'Gluable data have been obtained that gi\.es a new insight on the atomic-scale processes ässociated with the interaction ofGB with dislocations in steels. For insta'nce, it has been disco\.ered the key role of elementarydisconnections in the GB-dislocations interactions. Low critical stress for the elementary disconnections in the {1 12} GB allows it to 'very efficiently experience shear-coupled GB migration. This is the only GB where transmission of the pile-up has been observed, as only one elementary disconnection is enough to transform the Burgers vector of the reacted dislocation, so it is able to glide in the adjacent grain. Athe same 6me, there is no transmission in other studied CBs. The {332} GB can accept sexeral crystal dislocation forming new aynmetric interfaces at the reaction site. While the {1 16} GB, having several disconnections with Burgers vector parallel to the interface, is able to accommodate stresses by splitting the initial reaction product into new GB defects. On the other hand, there are no elementary disconnections associated with the {1 1 1} GB. This GB is the only one studied that does not experience shear-couple GB migration, instead the interface at the reaction is changed by shuffing of two atoms forming new interfaces and allowing the growth of one grain at expenses of the other. The appropriate choice ofGB allowed us to draw conclusions sufficiently general to be used in the development of large-scale models, which are indispensable tools for investigating the long-term evolution of these materials.

DOCTORAL DEGREE IN COMPUTER ARCHITECTURE

  • GUTIÉRREZ TORRE, ALBERTO: Distributed cloud-edge analytics and machine learning for transportation emissions estimation
    Author: GUTIÉRREZ TORRE, ALBERTO
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN COMPUTER ARCHITECTURE
    Department: (DAC)
    Mode: Normal
    Deposit date: 19/09/2022
    Deposit END date: 03/10/2022
    Thesis director: BERRAL GARCÍA, JOSEP LLUÍS | CARRERA PÉREZ, DAVID
    Committee:
         PRESIDENT: VITRIÀ I MARCA, JORDI
         SECRETARI: MUJAL COLILLES, ANNA
         VOCAL: GUIM BERNAT, FRANCESC
    Thesis abstract: In recent years IoT and Smart Cities have become a popular paradigm of computing that is based on network-enabled devices connected providing different functionalities, from sensor measures to domotic actions. With this paradigm, it is possible to provide to the stakeholders near-realtime information of the field, e.g. the current pollution of the city. Along with the mentioned paradigms, Fog Computing enables computation near the sensors where the data is produced, i.e. Edge nodes. This paradigm provides low latency and fault tolerance given the possible independence of the sensor devices. Moreover, pushing this computation enables derived results in a near-realtime fashion.This ability to push the computation to where the data is produced can be beneficial in many situations, however it also requires to include in the Edge the data preparation processes that ensure the fitness for use of the data as the incoming data can be erroneous. Given this situation, Machine Learning can be useful to correct data and also to produce predictions of the future values. Even though there have been studies regarding on the uses of data at the Edge, to our knowledge there is no evaluation of the different modeling situations and the viability of the approach. Therefore, this thesis aims to evaluate the possibility of building a distributed system that ensures the fitness for use of the incoming data through Machine Learning enabled Data Preparation, estimates the emissions and predicts the future status of the city in a near-realtime fashion. We evaluate the viability through three contributions.The first contribution focuses on forecasting in a distributed scenario with road traffic dataset for evaluation. It provides a robust solution to build a central model. This approach is based on Federated Learning, which allows training models at the Edge nodes and then merging them centrally. This way the models in the Edge can be independent but also can be synchronized. The results show the trade-off between accuracy versions training time and a comparison between low-powered devices versus server-class machines. These analyses show that it is viable to use Machine Learning with this paradigm.The second contribution focuses on a particular use case of ship emission estimation. To estimate exhaust emissions data must be correct, which is not always the case. This contribution explores the different techniques available to correct ship registry data and proposes the usage of simple Machine Learning techniques to do imputation of missing or erroneous values. This contribution analyzes the different variables and their relationship to provide the practitioners with guidelines for correction and data treatment. The results show that with classical Machine Learning it is possible to improve the state-of-the-art results.Moreover, as these algorithms are simple enough, they can be used in an Edge device if required.The third contribution focuses on generating new variables from the ones available with a ship trace dataset obtained from the Automatic Identification System (AIS). We use a pipeline of two different methods, a Neural Networks and a clustering algorithm, to group movements into movement patterns or\emph{behaviors}. We test the predicting power of these behaviors to predict ship type, main engine power, and navigational status. The prediction of the main engine power is compared against the standard technique used in ship emission estimation when the ship registry is missing. Our approach was able to detect 45\% of the otherwise undetected emissions if the baseline method was to be used. As ship navigational status is prone to error, the behaviors found are proposed as an alternative variable based in robust data.These contributions build a framework that can distribute the learning processes and that resists network failures in low-powered devices.

DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING

  • ALAVI, SEYED HAMIDREZA: Building Information Modeling for facility managers.
    Author: ALAVI, SEYED HAMIDREZA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING
    Department: (DECA)
    Mode: Normal
    Deposit date: 14/09/2022
    Deposit END date: 28/09/2022
    Thesis director: FORCADA MATHEU, NURIA
    Committee:
         PRESIDENT: POUR RAHIMIAN, FARZAD
         SECRETARI: CASALS CASANOVA, MIQUEL
         VOCAL NO PRESENCIAL: FUERTES CASALS, ALBA
    Thesis abstract: A Decision Support System (DSS) can help facility managers to improve building performance, occupants¿ comfort, and energyefficiency during the Operation and Maintenance (O&M) phase. These DSSs are normally data-intensive and have specific datarequirements. Building Information Modeling (BIM) has the potential to advance and transform facilities O&M by providing facilitymanagers with a digitalized virtual environment that allows them to retrieve, analyze, and process such data. However, theimplementation of BIM in O&M phases is still limited. The majority of issues in the BIM-O&M context lie in the interoperability betweendifferent software that requires different data structures and formats. In a BIM environment, there are issues associated withextracting, storing, managing, integrating, and disseminating data so that interoperability is assured.Considering the aforementioned aspects, the aim of this thesis is to enable interoperability between BIM models and the DSSs forbuilding performance aspects such as building condition, maintenance, and occupants¿ comfort. This integration automatizes thedata transfer process which can assist Facility Management (FM) team in properly establishing the necessary measurements tomoderate the negative consequences on buildings and thereby improve their performance and occupants¿ comfort. The approachcan also provide FM teams with an effective platform for data visualization in a user-friendly manner that can assist in integratingdigital insights into FM decision-making processes and converting them into positive strategic actions. The proposed approach isvalidated in existing software as a case study. It is possible to demonstrate the applicability of this approach by ensuring that itsinteractions and outcomes are feasible using case studies. Case studies also identify how much the task efficiencies are incomparison with the manual method, helping facility managers to optimize operation strategies of buildings in order to enhance theirperformance. Verification tests are also performed on the information exported from a software program.The results demonstrate an efficiency increase in high-quality FM data collection for different kinds of DSS, reducing the time andeffort that the FM team spends on searching for information and entering data. A Dynamo script is designed to allow administratorsto include as much information as they wish in BIM models. Moreover, a novel approach is proposed to create a new category in BIMto assist public and business administrations with managing assets efficiently. In addition, building performance aspects can also beanalyzed using the proposed method of integrating occupants' feedback into BIM models. By implementing the proposed approach,FM teams are able to correctly establish measurements which can be applied to mitigate the negative effects on buildings, thusimproving their performance and enhancing their occupants¿ comfort. Besides, the proposed approach enables BIM to be a moreuseful tool for visualization by using the most appropriate charts and formatting.

DOCTORAL DEGREE IN ELECTRICAL ENGINEERING

  • CORONAS HERRERO, SERGIO: Aportació a l¿anàlisi i gestió tècnica-econòmica dels sistemes de generació distribuïda amb energies renovables i microxarxes. Introducció a la presa de decisions en el context normatiu actual.
    Author: CORONAS HERRERO, SERGIO
    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: Article-based thesis
    Deposit date: 21/09/2022
    Deposit END date: 05/10/2022
    Thesis director: DE LA HOZ CASAS, JORGE | MARTIN CAÑADAS, MARIA ELENA
    Committee:
         PRESIDENT: PALACIN FARRE, PEDRO
         SECRETARI: MONJO MUR, LLUÍS
         VOCAL: TERMES RIFÉ, MONTSERRAT
    Thesis abstract: In recent years, the development of a generation system based on renewable energies has become the backbone of the energy policies of most countries in the world in the search for the decarbonization of the energy sector to contain planet global warming. The remarkable progress achieved in the reconversion of the electricity generation sector worldwide towards a renewable model has been acquired in large part by the public support policies for renewable generation technologies implemented.Spain has not been an exception, but rather a particularly relevant case study due to the numerous legislative changes experienced in the regulation of renewable energies in the last two decades. Specifically, Spain went from being one of the world's leading countries in the promotion of renewable energy sources, especially solar and wind, through the implementation of legal-economic frameworks with high associated economic returns during the first decade of the 2000s, to being one of the first countries to retroactively apply containment measures to reduce the disproportionate development costs that put the financial sustainability of the Spanish electricity sector at risk, giving rise to very unfavourable conditions for renewable assets in the second decade of the 2000s.In this sense, this thesis, presented as a compendium of articles, is developed within the line of research focused on the analysis and synthesis of regulatory frameworks to optimize decision-making in the design and management of energy assets, contributing to the state of the art from three papers published in indexed journals.First of all, this project aims to provide the academy with an exhaustive review of the evolution of solar energy policy in Spain during the period 1998¿2020, through the first review article. Specifically, this study focuses on solar generation technology (photovoltaic and concentrating solar power) that has the potential to become the most abundant energy resource in the world, with Spain having the most abundant solar resource in the entire European Union. This review of the academic literature integrates and evaluates all the relevant information from published research works, as well as form the regulations in force during the period 1998¿2020, allowing readers to understand the importance of energy policies to promote these solar assets.In this line, and in relation to the economic analysis of these assets based on the regulatory frameworks applied, this project through the second paper analyses the impact of regulatory retroactivity on the economic valuation of Spanish concentrating solar power assets in the medium and long term by using a stochastic model, seeking to improve decision-making regarding the design and management of these assets and reduce the impact on investment risk.Finally, once the importance of regulatory frameworks on the economic results of energy assets has been verified, this work addresses in the third paper the definition of a methodology aimed at obtaining simplified models that incorporate all the variables associated with the problem in the energy management model of renewable assets with a long operating life under a high degree of uncertainty. Accordingly, it seeks to solve a real problem by facilitating operational decision-making and the management of renewable assets in the medium and long term, in order to optimize their economic results.The line of work defined and shown with this compendium of articles clearly demonstrates the importance of regulatory frameworks and the need for their incorporation in both economic and energy decision-making. The methodology and results of the thesis are currently applied to the concentrating solar power and photovoltaic assets of the Spanish generation system, improving their optimal and economically efficient management.
  • GARCÍA MUÑOZ, FERNANDO ESTEBAN: Mathematical programming-based models for the distribution networks' decarbonization
    Author: GARCÍA MUÑOZ, FERNANDO ESTEBAN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
    Department: (DEE)
    Mode: Normal
    Deposit date: 23/09/2022
    Deposit END date: 07/10/2022
    Thesis director: CORCHERO GARCIA, CRISTINA | DÍAZ GONZÁLEZ, FRANCISCO
    Committee:
         PRESIDENT: SPERTINO, FILIPPO
         SECRETARI: VILLAFÁFILA ROBLES, ROBERTO
         VOCAL: MELENDEZ FRIGOLA, JOAQUIM
    Thesis abstract: Climate change is pushing to decarbonize worldwide economies and forcing fossil fuel-based power systems to evolve into power systems based mainly on renewable energies sources (RES). Thus, increasing the energy generated fromrenewables in the energy supply mix involves transversal challenges at operational, market, political and social levels due to the stochasticity associated with these technologies and their capacity to generate energy at a small scale close to the consumption point. In this regard, the power generation uncertainty can be handled through battery storage systems (BSS) that have become competitive over the last few years due to a significant price reduction and are a potential alternative to mitigate the technical network problems associated with the intermittency of the renewables, providing flexibility to store/supply energy when is required. On the other hand, the capacity of low-cost generation from small-scale power systems (distributed or decentralized generation (DG)) represents an opportunity for both customers and the power system operators. i.e., customers can generate their energy, reduce their network dependency, and participate actively in eventual local energy markets (LEM), while the power system operator can reduce the system losses and increase the power system quality against unexpected external failures. Nevertheless, incorporating these structures and operational frameworks into distribution networks (DN) requires developing sophisticated tools to support decision-making related to the optimal integration of the distributed energy resources (DER) and assessing the performance of new DNs with high DERs penetration under different operational scenarios.This thesis addresses the distribution networks' decarbonization challenge by developing novel algorithms and applying different optimization techniques through three subtopics. The first axis addresses the optimal sizing and allocation of DGand BSS into a DN from deterministic and stochastic approaches, considering the technical network limitation, the electric vehicle (EV) presence, the users capacity to modify their load consumption, and the DG capability to generate reactive power for voltage stability. Besides, a novel algorithm is developed to solve the deterministic and stochastic models for multiplescenarios providing an accurate DERs capacity that should be installed to decrease the external network dependency. The second subtopic assesses the DN capacity to face unlikely scenarios like primary grid failure or natural disasters preventing the energy supply through a deterministic model that modifies the unbalance DN topology into multiple virtual microgrids (VM)balanced, considering the power supplied by DG and the flexibility provided by the storage devices (SD) and demand response (DR). The third axis addresses the emerging transactive energy (TE) schemes in DNs with high DERs penetrationat a residential level through two stochastic approaches to model a Peer-to-peer (P2P) energy trading. To this end, the capability of a P2P energy trading scheme to operate on different markets as day-ahead, intraday, flexibility, and ancillaryservices (AS) market is assessed, while an algorithm is developed to manage the users' information under a decentralized design.
  • ROMERO DURAN, DAVID: Comportamiento eléctrico de los compuestos de carbono (CFRP). Implicaciones para el modelado y fabricación de palas de aerogenerador con elementos estructurales que incorporan compuestos de CFRP
    Author: ROMERO DURAN, 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 ELECTRICAL ENGINEERING
    Department: (DEE)
    Mode: Normal
    Deposit date: 23/09/2022
    Deposit END date: 07/10/2022
    Thesis director: MONTAÑA PUIG, JUAN | VAN DER VELDE, OSCAR ARNOUD
    Committee:
         PRESIDENT: MARCH NOMEN, VICTOR
         SECRETARI: BOSCH TOUS, RICARDO
         VOCAL: HERMOSO ALAMEDA, BLAS
    Thesis abstract: Carbon fiber reinforced composites (CFRP) have been introduced in a very significant way in all areas of industry and the wind energy sector has been no exception. Due to the size of today's wind turbines and the operating environment in which they are usually found, this sector is facing a major challenge: protecting these structures against atmospheric discharges. Wind turbine blades (WTB) are the most exposed elements to these phenomena and, given the current dimensions and the expected further growth, it is increasingly common for them to incorporate CFRP composite materials. The electrical behavior of these materials and how to integrate them into the lightning protection system (LPS) still have many issues to be resolved.This thesis presents an extensive experimental study through which we wish to provide knowledge in this direction, in order to better understand the behavior of this type of materials both for their subsequent modeling and for their integration in the LPS of a WTB. Thus, in the central chapters (Chapters 4 and 5) of this thesis, a large number of tests and very detailed procedures will be shown, which will allow, later on, to be reproduced and compared.The first part of the experimentation is oriented towards the determination and characterization of the material, given its anisotropic behavior. All the tests and results shown here allow to know the difficulties in the characterization of this type of materials from the electrical point of view and a procedure is proposed which, given the results obtained, is understood to allow to reach a better quality information. At the same time, given the dependence that all these tests show on the electrical connections with this type of materials, a detailed study on the effect of the connections is also carried out.The second experimental part of this work is oriented towards the study of surface connections on composite materials in order to bond them and integrate them with the LPS. In this case, the dependence of the size of the specimens and the type of current injected are taken into account, since not only direct current is used, but also lightning current pulses are injected. In this way, more comprehensive conclusions can be drawn about the behavior of this type of connections with CFRP composite materials.This document is completed with an introduction and motivation for the development of the thesis (Chapter 1), followed by a detailed review of the structure of WTBs, the composite materials used for their fabrication, a review of the protection standard and modeling techniques (Chapter 2). Chapter 3 is devoted to a review of the materials used, the techniques applied to prepare the material for testing and the measurement methods used to obtain the material characteristics.After all the experimental study and its analysis, some contributions and works carried out in relation to this thesis are shown (Chapter 6) and the document ends with the conclusions and proposals for future works (Chapter 7).
  • ZIEGLER, ANDREAS: Possibilities and Limitations of Active Battery Management Systems for Lithium-Ion Batteries
    Author: ZIEGLER, ANDREAS
    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: 23/09/2022
    Deposit END date: 07/10/2022
    Thesis director: MONTESINOS MIRACLE, DANIEL | ACKVA, ANSGAR
    Committee:
         PRESIDENT: ARNDT, BERNHARD
         SECRETARI: DÍAZ GONZÁLEZ, FRANCISCO
         VOCAL: BOHN, GUNTHER
    Thesis abstract: Lithium-Ion Batteries (LIBs) are being used in more and more areas of application. At the same time, their chemical composition and their designs are constantly evolving. Major developments are also taking place in the field of Battery Management Systems (BMSs), which are essential for the safe operation of LIBs. The focus is on intelligent charge redistribution between individual cells, called Active Balancing (AB). This thesis deals with the possibilities and limitations of AB. An empirical long-term experiment provides new insights into the ageing behaviour of batteries that are actively balanced during their entire service life.The main objective of this work is to to demonstrate influences on the ageing behaviour of batteries that are still unknown at present. A literature study shows that previous work in this area is often based on theoretical approaches and rarely has a functional proof through measurement results. Most significant statements from literature are examined. These include the increase in discharge capacity, energy efficiency and service life associated with AB, as well as lower parameter variation of the individual cells installed in the battery.Before starting the empirical experiment, the current state of the art is captured and a universal AB topology is selected from a large number of known systems. The operating behaviour as well as the balancing algorithms are explained in detail in order to be able to understand the influences occurring during the ageing of the batteries. The ageing experiment itself is a comparison test between commercial Passive Balancing (PB) and the novel AB. Two identical battery packs are aged under uniform conditions, but with the two different BMSs mentioned above. At the end of the ageing process, the battery packs are disassembled and the parameters of all individual cells are determined for further investigation.The main contribution of this work is the proof of effects through AB, especially with large battery loads. Both the increase in discharge capacity and the service life are demonstrated. The work shows how parameter variation of individual cells can be made visible during operation. It also presents diagnosis and calculation methods. The energetic efficiency of the batteries cannot be increased, since the self-consumption of the power electronics of the AB system is always higher than with PB. However, the overall efficiency of the battery increases due to an increase in capacity and an extension of the service life. The thesis also shows that with lower battery loads, the use of AB is not beneficial any more or may lead to negative effects. In such applications conventional PB is sufficient. The results obtained during pack ageing are additionally substantiated and extended by the measurement results of the individual cells.At the end of the thesis, all results and contributions are summarised. Suggestions for optimisation as well as further research ideas are presented as a possible starting point for further scientific studies.

DOCTORAL DEGREE IN MARINE SCIENCES

  • BALLESTEROS MASCARELL, AINARA: Pelagia noctiluca (Cnidaria: Scyphozoa) como un modelo de investigación industrial: Mejoras en las técnicas de acuicultura y medidas preventivas contra sus picaduras.
    Author: BALLESTEROS MASCARELL, AINARA
    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: 15/09/2022
    Deposit END date: 29/09/2022
    Thesis director: GILI SARDÁ, JOSEP MARIA | JOURDAN RENE, ERIC
    Committee:
         PRESIDENT: MILISENDA, GIACOMO
         SECRETARI: SALVO, VANESA-SARAH
         VOCAL: BOSCH BELMAR, MARIA DEL MAR
    Thesis abstract: Jellyfish stings cause discomfort to users of the marine environment, who sometimes require medical assistance. Although jellyfish stings are common today, the scientific community remains in disagreement on how to act in first-aid protocols. Most of the recommended compounds are based on empirical knowledge, and they are difficult to transfer to the cosmetic or pharmaceutical industry due to the lack of knowledge of their mechanisms of action.In the Mediterranean Sea, the mauve stinger Pelagia noctiluca (Cnidaria: Scyphozoa) is the most important jellyfish due to its high frequency, abundance, wide distribution and severity of its sting. This jellyfish is the cause of a high number of stings, which is why it is considered a target species in the development of tools for the prevention and mitigation of jellyfish stings. P. noctiluca is one of the few jellyfish with a holoplanktonic life cycle, a peculiarity that has limited its study in different areas of knowledge under controlled conditions.The main objective of this PhD thesis was to inhibit the discharge of P. noctiluca stinging cells (cnidocytes) through active ingredients that could be incorporated into cosmetic products intended to prevent and mitigate the effects of jellyfish stings. As secondary objectives highlighted: expanding knowledge in the biology of P. noctiluca, its aquaculture techniques, and the implication of topical solutions in first-aid protocols.In Chapter 1, the morphological and anatomical characteristics of P. noctiluca were described, including the first cnidome description ¿ set of stinging cells ¿ through growth in aquaculture. Cnidocytes were classified into four nematocyst types: a-isorhiza, A-isorhiza, O-isorhiza, and eurytele; being the types a-isorhiza and eurytele the most important throughout the life cycle, and O-isorhiza and eurytele the main ones involved in its sting.In Chapter 2, the life cycle of P. noctiluca was optimized in aquaculture. Total body diameter, instantaneous growth rate, and survival rate were monitored in the presence of different feeding regimens. For the first time, the third generation of individuals was obtained in the presence and absence of gelatinous prey (Aurelia sp.). In order to improve jellyfish aquaculture techniques, in Chapter 3, the design of an aquarium for the growth of the early life cycle stages in flow-through or closed systems was presented. Its configuration allows changing the mesh screen in situ, adjusting the size of the mesh according to the stages of the cycle, as well as the prey offered.The use of vinegar, a compound widely used as a rinse solution after jellyfish stings, was contraindicated in Chapter 4. This compound triggered the discharge of all types of nematocysts by the tentacle solution assay (TSA). In addition, vinegar did not decrease the hemolytic areas produced after inoculation of the venom in the tentacle skin blood agarose assay (TSBAA). Finally, in Chapter 5, the discharge of P. noctiluca nematocysts was inhibited with hydroxyacetophenone and Symsitive¿ in combination with butylene glycol, two active ingredients widely used in the cosmetics sector. Furthermore, hemolytic areas decreased after the stinging event compared to seawater, a non-inhibitory compound. These compounds were considered of high value because they are also beneficial for treating skin damage, relieving pain and burning sensations; clinical signs and symptoms typical of jellyfish stings.Overall, this PhD thesis provided significant advances in the area of knowledge of the biology of P. noctiluca, aquaculture and management of jellyfish stings.
  • OBIOL PLANA, ALEIX: Return of the marine heterotrophic flagellates: diversy, distribution and gene expression patterns.
    Author: OBIOL PLANA, ALEIX
    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: 21/09/2022
    Deposit END date: 05/10/2022
    Thesis director: MASSANA MOLERA, RAMON
    Committee:
         PRESIDENT: ARNDT, HARTMUT
         SECRETARI: RICHTER, DANIEL
         VOCAL: ALONSO SAEZ, LAURA
         VOCAL NO PRESENCIAL: SÁNCHEZ MARTÍNEZ, OLGA
         VOCAL NO PRESENCIAL: DEL CAMPO GARCIA-RAMOS, JAVIER
    Thesis abstract: Marine heterotrophic flagellates (HF) are very small (2-5 µm) unpigmented protists that are dominant bacterial grazers in the ocean, where they link the transfer of carbon from bacterial cells to higher trophic levels. Through their bacterivorous activity, they also act as nutrient recyclers that allow for regenerated primary production, and they are partially responsible of keeping bacterial abundances in the ocean fairly constant. HFs are widespread throughout the eukaryotic tree of life, ubiquitous in the plankton and display a high functional diversity. During the last decades of the twentieth century, a growing interest in this functional group occurred, and studies were performed to characterize their ecological role. However, this initial attention diminished due to the difficulty to study natural HF species, as they possess few morphological traits for identification and generally remain uncultured.Consequently, HFs have been often neglected in marine surveys, to the extent of becoming one of the most understudied components of the marine microbiome. With the advent of high-throughput sequencing and the reduction of sequencing costs, studying these protists at a high-resolution level became feasible. This thesis represents areturn to the study of HFs using these newly developed tools. We first investigated the distribution patterns of eukaryotic diversity along the water column of the ocean by metagenomics and compared the results with metabarcodingapproaches. This analysis revealed a clear separation of taxonomic groups between pico- (0.2-3 µm) and nanoplanktonic (3-20 µm) fractions, as well as between photic (0-200 m) and aphotic (>200 m) regions. While some groups were not well represented by metabarcoding approaches due to technical biases, HFs were generally notaffected by them. We then studied the diversity and distribution of HFs in the ocean using global metabarcoding datasets. With this, we identified a few dozens of HF species, most of them uncultured, as the dominant in surface and deep ocean regions. Many of these dominant species were present at relatively constant abundances, while others were influenced by temperature or displayed patchy distributions. Finally, we jumped from global patterns to study the gene expression of HFs in natural assemblages growing by bacterivory in unamended incubations. Theobtained results using metatranscriptomics sequencing showed similar functional dynamics between experiments done at different times of a seasonal cycle, with marked differences between incubation times. Genes related to cysteine peptidases as well as some glycoside hydrolases emerged as key components involved in the process of bacterivory. Overall, this thesis returns HFs back to the spotlight and creates a solid foundation on which to perform renewed research on the ecology and functional role of this group.

DOCTORAL DEGREE IN MECHANICAL, FLUIDS AND AEROSPACE ENGINEERING

  • ELMANSY, REDA MOHAMED YOUSYF ABDALLAH: Study of the flow around a square cylinder with an upstream splitter plate
    Author: ELMANSY, REDA MOHAMED YOUSYF ABDALLAH
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN MECHANICAL, FLUIDS AND AEROSPACE ENGINEERING
    Department: Department of Fluid Mechanics (MF)
    Mode: Normal
    Deposit date: 23/09/2022
    Deposit END date: 07/10/2022
    Thesis director: BERGADÀ GRANYÓ, JOSEP MARIA | MELLIBOVSKY ELSTEIN, FERNANDO PABLO
    Committee:
         PRESIDENT: MESEGUER SERRANO, ALVARO
         SECRETARI: PUJOL SAGARO, ANTONI
         VOCAL: HUERA HUARTE, FRANCISCO
    Thesis abstract: This PhD mostly focuses in studding the flow around a square cylinder with an upstream splitter plate and considering different velocity ratios between the upper and lower inlet velocities. The PhD is based in three main studies:1.-The flow instabilities, involving the transition from two dimensional to three dimensional flow, the Hopt, Neimark Sacker bifurcations as well as the road to chaos, all of them were determined as a function of the velocity ratio. A parametric study was also performed involving the instabilities performance as a function of the splitter plate length and the distance splitter plate square cylinder.2.-Two dimensional and full three dimensional CFD-DNS simulations were undertaken to find out the wake topology and aerodynamic performances such as, dynamic lift, drag, pressure and friction coefficients, Strouhal numbers, boundary layer dynamics as well as the different instability modes.3.- Wake past circular cylinder has been investigated to characterize the three-dimensional instability in the transitional regime when the boundary layer over the cylinder surface is laminar and shear layer separating the surface undergoes intermittently unstable displacements which manifests in the form of small time and length scale vortical structures. The wake in this flow regime is modestly turbulent and the streamwise velocity profiles across the flow stream feature typical U-shape profile.

DOCTORAL DEGREE IN NETWORK ENGINEERING

  • MOHAMMADZADEH, NASIBEH: Invoice Factoring through Blockchain Technology
    Author: MOHAMMADZADEH, NASIBEH
    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: 14/09/2022
    Deposit END date: 28/09/2022
    Thesis director: MUÑOZ TAPIA, JOSE LUIS | NOGOORANI, SADEGH DORRI
    Committee:
         PRESIDENT: HERNÁNDEZ GAÑÁN, CARLOS
         SECRETARI: ESPARZA MARTIN, OSCAR
         VOCAL: SILVA CÁRDENAS, CARLOS BERNARDINO
    Thesis abstract: Invoice factoring has been a popular way to provide cash flow for businesses. The primary function of a factoring system is to prevent an invoice from being factored twice. In order to prevent double factoring, many factoring ecosystems use one or several centralized entities to register factoring agreements. However, this puts a lot of power in the hands of these centralized entities and makes it difficult for users to dispute situations in which factoring data is unavailable, wrongly recorded or manipulated by negligence or on purpose.This thesis presents our research around the current problems of invoice factoring and our new solutions to solve this process using the blockchain technology. A public blockchain can keep a permanent, secure, ordered and transparent record of transactions which are then available for everyone at any time to view and verify.In this thesis, we start proposing a base solution, and we gradually enhance it. In the base protocol, we propose an architecture for invoicing registration based on a general blockchain. The blockchain platform builds trust between the parties by executing transactions correctly. We employed a smart contract to complete the registration process, and prevent double factoring. The smart contract provides for auditing and dispute resolution in such a way that privacy is protected and relevant information is alwaysavailable.In the second protocol, we add a relayer to our architecture for easier on-boarding. Only the relayer is required to submit blockchaintransactions, and pay the corresponding fees. Other participants can proxy their transactions through the relayer, and pay the relayer in fiat money. We also enhance our identity management and authentication using the concept of verifiable credentials (VC) in order to better comply with the Know-Your-Customer (KYC) regulation. In fact, in this architecture, participants use their decentralized identifiers (DIDs) and the DIDComm protocol for asynchronous and secure off-chain interactions.In the final protocol, we greatly enhance our smart contract with respect to the conditions it checks before registering an invoice factoring. We integrate non-interactive zero-knowledge proofs and cryptographic commitments into our solution. With these cryptographic tools in place, we can prevent a special type of denial of service (DoS) attack and better verify invoice details withoutcompromising privacy. Our protocols are very efficient in terms of blockchain costs. In particular, we only need one transaction to register an invoice factoring, and most of the details are recorded in low-cost blockchain storage. Our evaluations and comparison with the literature reveals that our protocols are superior to the related works with respect to efficiency, security, privacy, and ease ofuse.

DOCTORAL DEGREE IN PHOTONICS

  • JIMÉNEZ MACHADO, GERARD: Fundamentals of nonlinear interferometers and its use for optical coherence tomography
    Author: JIMÉNEZ MACHADO, GERARD
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN PHOTONICS
    Department: Institute of Photonic Sciences (ICFO)
    Mode: Normal
    Deposit date: 20/09/2022
    Deposit END date: 04/10/2022
    Thesis director: PEREZ TORRES, JUAN
    Committee:
         PRESIDENT: PRUNERI, VALERIO
         SECRETARI: ALONSO GONZALEZ, MIGUEL ANGEL
         VOCAL: GRÄFE, MARKUS
    Thesis abstract: This thesis, mostly experimental, is based on two fundamental pillars: nonlinear interferometers and Optical Coherence Tomography (OCT). Nonlinear interferometers are a class of interferometers that exhibit nonclassical phenomena brought on by nonlinear elements, such as optical parametric amplifiers and parametric down-conversion (PDC) nonlinear crystals. OCT is a non-invasive imaging technique that allows to obtain images with high axial and cross-sectional resolution of a wide variety of samples.The first novel contribution of this thesis is an experimental scheme that combines the two ideas: an OCT scheme based on a nonlinear interferometer. In these new approach the reflectivity of the sample translates in a loss of first-order coherence between two beams, that is the variable that is measured. In addition, it allows probing the sample with a wavelength different from the one that is measured. In this way, the penetration depth in the sample can be enhanced using longer wavelengths while using light at the optimal wavelength for detection.We present and implement two different experimental configurations. The first is a nonlinear interferometer based on induced coherence, or Mandel-type interferometer, that works in the low parametric gain regime of parametric down-conversion (PDC). The results presented here are a proof-of-concept, that can potentially offer new applications for OCT, but that are not meant to substitute traditional OCT systems. The second OCT scheme overcomes some of the limitations of the first scheme discussed above. It is an SU(1,1), or Yurke-type interferometer, that operates in the high parametric gain regime of parametric down-conversion. In addition to taking advantage of the salutary features of this new approach, it also enables obtaining values of power and axial resolution comparable to those of conventional OCT.The second novel contribution of this thesis is related to fundamental aspects at the heart of nonlinear interferometers. We discuss two experiments that study two important concepts behind the idea of induced coherence: quantum distinguishability and parametric amplification (stimulated emission). In the first experiment we propose a new experimental measure of quantum distinguishability and derive a complementarity relation between distinguishability and first-order coherence. In the second experiment, we contribute to the ongoing debate about the true role of quantum distinguishability and stimulated emission in explaining the induced coherence effect. Finally, we put forward theoretically a new scheme to retrieve transverse spatial information of a sample using a nonlinear interferometer, based on projecting the outgoing photons in selected spatial modes. We call this new proposal spatial spectroscopy, and it does not require a physical mechanical scan of the sample. We demonstrate the feasibility of the technique with a simple example. This last contribution constitutes a future proposal to be carried out with nonlinear interferometers, evidencing their great versatility and potential applications in new areas.

DOCTORAL DEGREE IN POLYMERS AND BIOPOLYMERS

  • HODÁSOVÁ, LUDMILA: Polymer-zirconia based ceramic composites produced by 3D-printing
    Author: HODÁSOVÁ, LUDMILA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN POLYMERS AND BIOPOLYMERS
    Department: Department of Chemical Engineering (EQ)
    Mode: Normal
    Deposit date: 21/09/2022
    Deposit END date: 05/10/2022
    Thesis director: FARGAS RIBAS, GEMMA | ARMELIN DIGGROC, ELAINE APARECIDA
    Committee:
         PRESIDENT: FERREIRA MORGADO, JORGE MANUEL
         SECRETARI: JIMENEZ PIQUÉ, EMILIO
         VOCAL: BRAVO LARA, FERNANDO
    Thesis abstract: Zirconia ceramic is widely used in numerous fields, such as electronics, machinery, and biomedical applications, due to its excellent properties as chemical resistance, thermal stability, electrical resistance, toughness, hardness, but also inertness and g biocompatibility. The 3D-printing technology has opened new doors for possible applications of zirconia and also allows for higher complexity of the shapes and structures, even for specimens with designed porosity, which would be until now unimaginable with traditional manufacturing methods like gel casting or cold isostatic pressing. The biocompatibility, inertness, and excellent aesthetic aspects of this ceramic make it also a preferred material for biomedical applications, more specifically in dentistry.However, application in the biomedical field has had some shortcomings, where the high hardness and brittleness of the material could cause discomfort or excessive wear. One of the aims of this thesis was to develop a new hybrid material that would complement the above-mentioned properties of zirconia and at the same time try to mimic the mechanical properties and biocompatibility of natural teeth using a combination of zirconia and acrylate polymer materials, while using additive manufacturing. The first part was focused on the development and manufacturing of such material. The idea of polymer-infiltrated ceramic networks (PICN), where a porous sintered ceramic structure is interpenetrated with a polymer matrix, was followed. The innovation of this technology was based on the 3D-printing of ceramic zirconia (3Y-TZP) scaffolds with designed porosity. After the optimization of the printing process, the 50% zirconia infill was chosen as the most appropriate porosity of the scaffold that was subsequently infiltrated with bisphenol A glycerolate dimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) copolymer. After the successful manufacturing of 3D-printed PICN and the proper infiltration of the copolymer, the physical-chemistry properties of the new material were characterized, as well as its mechanical properties. The bacterial adhesion was evaluated against Gram-negative Escherichia coli and Gram-positive Streptococcus salivarius bacteria lines, revealing, that although such samples do not have antimicrobial properties, they do not promote excessive bacterial growth either. Regarding biocompatibility, the cell assay using human osteoblasts (MG-63) was carried out showing good cell viability.To improve the antimicrobial properties of manufactured PICN, the surface was modified with the adhesion of silver nanoparticles, which were embedded in an enzymatically modified phenolated lignin matrix (Ag@PL NPs), obtained from renewable resources, to avoid metal particle oxidation. The functionalization of the surface of the hybrid material with such Ag NPs allowed the reduction of bacterial growth by 90% on the modified surface. The last part of this thesis focused on the improvement of osseointegration of zirconia surface in vitro. Although it is an inert material, surface modification is required to avoid possible failures of zirconia once implanted in vivo. A polydopamine methacrylate copolymer, which has proved antibiofilm formation properties, was applied to the surface of zirconia. Characterization of the surfaces has proven good viability of theMG-63 cell line and also a great adhesion of the polymeric nanofilm, produced by cold plasma to the surface of zirconia discs. Overall, this thesis describes the 3D printing of PICN structures, which have a macroporous structure for the correct infiltration of the copolymer. The synergy and good adhesion between these materials have given rise to a prototype whose mechanical properties simulate those for natural teeth

DOCTORAL DEGREE IN SUPPLY CHAIN AND OPERATIONS MANAGEMENT

  • AGUILAR GAMARRA, HARRY - NICK: Equilibrado de líneas de montaje en paralelo con estaciones multilínea y dimensionado de buffers
    Author: AGUILAR GAMARRA, HARRY - NICK
    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 SUPPLY CHAIN AND OPERATIONS MANAGEMENT
    Department: Department of Management (OE)
    Mode: Normal
    Deposit date: 22/09/2022
    Deposit END date: 06/10/2022
    Thesis director: PASTOR MORENO, RAFAEL | GARCÍA VILLORIA, ALBERTO
    Committee:
         PRESIDENT: ANDRÉS ROMANO, CARLOS
         SECRETARI: DOMÉNECH LÉGA, BRUNO
         VOCAL: DE CASTRO VILA, RODOLFO
    Thesis abstract: Assembly lines are mass production systems which are relevant in the manufacture of standard and customized products.One of the most elementary optimization problems in this field is the Assembly Line Balancing Problem (ALBP). ALBP consists of assigning a set of tasks to a set of ordered stations, satisfying some specific constraints, in such a way that one or more objectives are optimized.Nowadays, companies dedicated to production usually have more than one assembly line or multiple lines to face demand fluctuations, design reasons, group products in different lines, etc. The use of multiple lines located in parallel has attractedthe interest of researchers in the last years. Parallel assembly lines are two or more lines that, if they are close enough, can be balanced together using shared stations (multi-line stations) between adjacent lines. In a multi-line station, the operatorperforms tasks assigned to his/her station of two adjacent lines in the cycle time of each line.Parallel Assembly Lines Balancing Problem (PALBP) can have lines with different cycle times. As a consequence of working with different cycle times, the systems with multi-line stations may have to produce in batches. In that case, the use of buffersin multi-line stations may be needed. The review of the state-of-the-art of PALBP reveals that no studies consider the use of some type of buffers in the case of production in batches. It should be noted that not considering the need (existence andsizing) of buffers in the PALB with lines with different cycle times can lead to the design of academic solutions that cannot be implemented in the industry.This doctoral thesis deals with the parallel assembly lines balancing problem and buffer sizing (PALBP-B). Precisely, PALBPB consists of a PALB system with multi-line stations and lines with different cycle times, in which there is the possibility of needing buffers. The problem of study in this thesis focuses on the PALBP-B of straight lines and single model.The PALBP-B resolution consists of two (sub)problems that should be solved simultaneously: 1) line balancing: assigning tasks to stations (and its definition as regular or multi-line stations); and 2) buffers sizing in the multi-line stations.The review of the state-of-the-art reveals that the problem presented in this thesis has not been studied in the literature. This implies defining and formalising the PALBP-B. First, the buffer sizing (sub)problem is characterized and defined, and a mixed integer linear programming (MILP) model and two modifications derived from it are presented for its optimal resolution. In addition, non-exact procedures (heuristics and metaheuristic) are also presented to solve real-size instances. Secondly, nonexact procedures (heuristics and metaheuristics) are presented in order to solve the PALBP-B, that is, the line balancing (sub)problem and the buffer sizing (sub)problem (using the procedures developed previously for this purpose) together.All the methods developed to solve the buffer sizing (sub)problem are evaluated via a computational experiment based on a set of instances generated for this purpose. The approximate approaches developed to solve the PALBP-B are evaluated viaan exhaustive computational experiment based on a set of realistic instances from the literature.

DOCTORAL DEGREE IN URBANISM

  • SANDOVAL VÁSQUEZ, JUAN CARLOS: La construcción del territorio de la Amazonía ecuatoriana. Una mirada desde las huellas de las disputas civilizatorias
    Author: SANDOVAL VÁSQUEZ, JUAN CARLOS
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN URBANISM
    Department: Department of Architectural Design (PA)
    Mode: Normal
    Deposit date: 23/09/2022
    Deposit END date: 07/10/2022
    Thesis director: SABATE BEL, JOAQUIN | LLOP TORNE, CARLOS JUAN
    Committee:
         PRESIDENT: SOTOCA GARCIA, ADOLFO
         SECRETARI: HIGUERAS GARCIA, ESTER
         VOCAL: SALTOS GALARZA, WASHINGTON NAPOLEON
    Thesis abstract: This work strives to develop an interpretative reading of the process of configuration of the Amazonian territory of Ecuador, a vast territory with an enormous natural predominance and important biological and cultural diversity. The objective of this thesis is to contribute to the understanding of the construction of this territory, to its relearning of knowledge. The work is based on the idea that the traces in the Amazonian territory show the civilization disputes, the forms of territorial occupation of the indigenous peoples and nationalities have been systematically ignored and underestimated, which have been tried to be changed by imposing other patterns of territorial occupation. Dispersed forms of occupation have been considered a problem that must be corrected by concentrating the population in urban settlements. These logics have remained in tension during the last 500 years in which the particularities of the territory have also produced particular results in the configuration of the Ecuadorian Amazon, a configuration that is currently more drastically marked by new ideas that in practice replicate old habits. In order to understand these processes, the work presents four main chapters. The first one describes a long process of confrontation that began in the 16th century and lasted until the middle of the 20th century, in which a missionary project intends to impose new patterns of territorial occupation on indigenous peoples. The ways of occupying the territory are confronted and, although they are antagonistic, they mutually stimulate each other, concentration and dispersion appear as constants in this process that generally prefigures (not configures) the Amazonian territory we know today. The second chapter explains the existence of an internal colonization project developed by the State, which violently occupied and transformed the region in the second half of the 20th century. In this context, modern Amazonia is configured where the Amazonian cities emerge as a by-product, whose forms show their particularities, as they present their own characteristics as a result of the fusion of the important geographical and natural influences as well as the aftermath of the previous missionary project. The third chapter explains where and how the indigenous population settled, makes a historical approach to their transformations, and explains how these two opposing forms of territorial construction end up complementing each other. The fourth chapter explains the emergence of the "New Amazon" (2007 - 2017), a new regulatory framework and existing economic resources drive several urban projects, which from the State, intend to reverse years of abandonment and poverty, among its objectives is to improve the quality of life of indigenous population and nationalities. However, in practice, the opposite has been done, building projects that obviate the existing specificities, imposing exogenous patterns of territorial occupation that significantly change the ways of living, replicating colonial practices of past centuries. Finally, the work explains, from the ways of inhabiting the territory, how indigenous population continues to face challenges as great as those they faced in colonial times, but also demonstrates their capacity, not only of resistance, but also of adaptation to overcome the challenges.

Last update: 24/09/2022 04:30:26.