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Theses authorised for defence

DOCTORAL DEGREE IN AEROSPACE SCIENCE AND TECHNOLOGY

  • CHEN, JIANLIN: Spacecraft state propagation and orbit determination using jet transport
    Author: CHEN, JIANLIN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN AEROSPACE SCIENCE AND TECHNOLOGY
    Department: Department of Physics (FIS)
    Mode: Change of supervisor
    Deposit date: 16/03/2021
    Reading date: 23/04/2021
    Reading time: 08:00
    Reading place: Seminar room 511, 5th floor of No.3 building, School of Aeronautics, Northwestern Polytechnical University. Videoconferència zoom https://us02web.zoom.us
    Thesis director: MASDEMONT SOLER, JOSEP JOAQUIM | GOMEZ MUNTANÉ, GERARD | YUAN, JIANPING
    Committee:
         PRESIDENT: LI, HENGNIAN
         SECRETARI: ZHENG, ZIXUAN
         VOCAL: LIU, GUIZHONG
         VOCAL: YUE, XIAOKUI
         VOCAL: BAOYIN, HEXI
    Thesis abstract: The motion of space objects is strongly nonlinear and non-integrable since it is not only affected by the Keplerian central gravity of the Earth, but also subjected to some complex perturbations. Either an accurate and efficient closed-form analytical solution or numerical integration solution is hard to obtain due to the rapid time-varying characteristics of the dynamics. As an alternative, some useful methods, such as covariance analysis and unscented transformations, have been developed at the cost of accuracy loss. There is no doubt that Bayesian orbit estimators based on these state transition methods would inherit the weaknesses. That is, the problem is either a bad prediction accuracy or a low computational efficiency. To alleviate this dilemma, a set of nonlinear propagators and estimators have been developed. In particular, this thesis proposes a specific polynomial algebraic software Jet Transport (JT), which enables to perform the precise and efficient Taylor or Chebyshev polynomial algebra and its implementation in nonlinear state propagators and estimators.An efficient polynomial operation tool has been proposed. This tool defines a series of polynomial algebraic manipulation in a modern computer, such as polynomial storage, addition, subtraction, multiplication, division, differentiation, integration, composition, polynomial-based integrators and polynomial evaluation. In overall, the methodology provides an efficient and accurate way to calculate arbitrary order Taylor and Chebyshev polynomials for practical problems defined by nonlinear functions or ordinary differential equations.Efficient and accurate spacecraft trajectory propagations are put forward. An advanced Monte Carlo method is constructed by combining high order polynomial propagators with the polynomial evaluation at real vectors. The former technique employs either Taylor or Chebyshev polynomials to approximate the flow of the dynamics, while the latter one is used to transport state vectors in a neighborhood of an initial state to determine statistical distributions.A JT-based augmented high order extended Kalman filter is proposed (JT-AHEKF). Since the JT-AHEKF filter employs high order Taylor expansions to achieve the a priori prediction of the state and measurement vectors, it enables to extract more nonlinear information from the models, such that both spacecraft trajectories and associated parameters are estimated accurately, even considering large state deviations or sparse measurements. A standard JT-based high order extended Kalman filter is deduced (JT-HEKF) by degrading the JT-AHEKF filter without consideration of parameter estimation.To avoid the pollution of false measurements, three fault-tolerant strategies have been presented for the JT-HEKF filter. These practical strategies are proposed based on either the direct abandon of identified false measurements or the adaptive adjustment of measurement noise covariance matrices using a single scale factor and an adaptive scale matrix.An adaptive order-switching strategy tailored for the JT-HEKF filter (JT-OSHEKF) has been proposed. Although, to a great extent, the JT-HEKF filter reaches a superior balance between the computational accuracy and efficiency, its continuous usage in a whole estimation process can be uneconomic since a JT-HEKF filter might be not necessary at the filter steady stage. A specific algorithm has been designed to dynamically switch the filter order within one single run, making the filtering process even more efficient.To conclude, this thesis proposes a set of nonlinear state propagators and estimators using polynomial expansion techniques, whose high efficiency and accuracy have been tested in propagation and estimation problems involving geosynchronous trajectories. Note that these propagators and filters can be not only applied in practical space missions, but also employed to achieve the state prediction and estimation in general engineering problems.

DOCTORAL DEGREE IN APPLIED MATHEMATICS

  • COSTA MIRADA, NÚRIA: Long-term privacy in electronic voting systems
    Author: COSTA MIRADA, NÚRIA
    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: Department of Mathematics (MAT)
    Mode: Normal
    Deposit date: 08/03/2021
    Reading date: 14/04/2021
    Reading time: 10:00
    Reading place: FME - Videoconferència e-meet: https://meet.google.com/ezh-ckis-phe
    Thesis director: MORILLO BOSCH, MARIA PAZ
    Committee:
         PRESIDENT: RÀFOLS SALVADOR, CARLA
         SECRETARI: HERRANZ SOTOCA, JAVIER
         VOCAL: GUASCH CASTELLÓ, SANDRA
    Thesis abstract: This PhD thesis focuses on lattice-based cryptography and how to apply it to build post-quantum online voting systems. It is the result of the research done by the author at Scytl in close collaboration with Dr. Paz Morillo, from the Department of Applied Mathematics at UPC and Ramiro Martínez, PhD student. As part of her work at the electronic voting company Scytl, the author has participated in the design of several electronic voting systems as well as in their implementation, by providing support to the development team. Nevertheless, all these systems use standard and well-known cryptographic primitives, i.e., not lattice-based primitives, to ensure that the security requirements are fulfilled. Due to this, one of the main challenges of this PhD has been to start researching on a field which was not familiar to the author and contribute to its state of the art. This has allowed the company to enter the post-quantum world by participating in a project which aims to implement a lattice-based online voting system. The thesis has the following contents: an introduction to the lattice theory by describing some of its basic concepts and the computational problems in which the security of lattice-based cryptosystems relies. In this first part it is also described in detail those cryptosystems that are used as building blocks of three new protocols proposed in the thesis: a lattice-based coercion-resistant cast-as-intended protocol, a post-quantum mix-net and a fully post-quantum proof of a shuffle. The former is the lattice version of an existing protocol and allows the voter to check that the vote cast contains the selected voting options. The second and third protocols are the result of the research on lattice-based mix-nets. Two constructions are proposed: the first one allows to demonstrate that a mix-node has permuted and re-encrypted a list of RLWE ciphertexts without modifying them, but it cannot be considered fully post-quantum since the binding property of the commitment scheme relies on classical computational problems. The second one is fully post-quantum since all the cryptographic schemes used for building it, i.e., commitment scheme and zero-knowledge proofs, are based on lattices. Last but not least, for this second proposal a security definition and a proof of security are also provided. Finally, the last part of the thesis consists of building a post-quantum online voting system using as building blocks the protocols already presented and existing lattice-based constructions. This system is considered secure under quantum attacks and provides long-term privacy. It also guarantees vote anonymity, vote authenticity, vote integrity, individual verifiability and receipt-freeness. The algorithms involved in each phase are described in detail as well as the interaction among the participants. An implementation of this system is not given as part of this thesis although a lattice-based online voting system based on that is already being implemented at the company.
  • TOZZI, CATERINA: A theoretical and computational study of the interaction between biomembranes and curved proteins
    Author: TOZZI, CATERINA
    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: 24/03/2021
    Reading date: 30/04/2021
    Reading time: 18:00
    Reading place: FME - Videoconfèrencia e-meet:https://meet.google.com/uwv-crmw-zew
    Thesis director: ARROYO BALAGUER, MARINO
    Committee:
         PRESIDENT: RANGAMANI, PADMINI
         SECRETARI: CAMPELO AUBARELL, FELIX
         VOCAL: PAGONABARRAGA MORA, IGNACIO
    Thesis abstract: Organelles are the smallest functional parts of eukaryotic cells. Among them, some are membrane-bound such as the nucleus, the endoplasmic reticulum, or the Golgi apparatus, each of them with essential biological functions. In order to accomplish cell functions, membranes enclosing these organelles continuously adapt their shapes through the out-of-equilibrium interaction with macro-molecules, notably proteins.During the life of cells, proteins are main actors in membrane bending dynamics since they have the ability to impinge their curvature onto the membrane, and generate transiently highly curved structures, such as tubes and spherical buds. How proteins can remodel the different organelles has been broadly studied in equilibrium, but a clear understanding of the complex chemo-mechanical problem that drives membrane reshaping out-of-equilibrium is still lacking.In the first Part of the thesis we develop a general theoretical and computational framework for the dynamics of curved proteins adhered to lipid membranes. The theory is based on a nonlinear Onsager's principle, a variational method for irreversible thermodynamics. The resulting governing equations and numerical simulations provide a foundation to understand the dynamics of curvature sensing, curvature generation, and more generally membrane curvature mechano-chemistry, as illustrated by a selection of test cases. We show that continuum modeling is a powerful instrument to describe the protein-membrane interaction. However, this model does not account for the orientational order of proteins and its derivation lacks a microscopic basis.To address these limitations, in the second Part of the thesis we develop a mean-field density functional theory to predict the orientational order and evaluate the free-energy of ensembles of elongated and curved objects, such as BAR proteins, on curved membranes. This kind of protein may adopt different states of orientational order, from isotropic to nematic. The theory is tightly coupled to the microscopic properties of the proteins and explains how a density-dependent isotropic-to-nematic transition is modified by the anisotropic underlying curvature of the membrane. This work lays the ground to understand the interplay between the molecular organization of proteins and the membrane shape dynamics. We explore the coexistence of isotropic and nematic phases on differently curved lipid membranes. We explain, both experimentally and through modelling, how a BAR protein binds on differently curved membrane templates and reshapes them based while modifying their microscopic organization. Our results broaden our understanding of the reshaping dynamics by BAR proteins on mechanically constrained membranes, and provide a framework to understand biological responses involving BAR proteins to membrane-mediated mechanical stimuli.

DOCTORAL DEGREE IN ARCHITECTURAL, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY

  • MIRBAGHERI, MAHSA: Urban cemetery biophilic integration for human well-being (An applied case study of Tehran, Iran)
    Author: MIRBAGHERI, MAHSA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN ARCHITECTURAL, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY
    Department: Department of Architectural Technology (TA)
    Mode: Normal
    Deposit date: 25/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: PARDAL MARCH, CRISTINA | ROCA BLANCH, ESTANISLAO
    Committee:
         PRESIDENT: GARCÍA VÁZQUEZ, CARLOS
         SECRETARI: MARTI CASANOVAS, MIQUEL
         VOCAL NO PRESENCIAL: DOS SANTOS FERREIRA DA FONSECA BENTO, PEDRO JOSÉ
    Thesis abstract: Cemeteries are an ancient reality, and while their basic function has not changed, their physical layout as well as the symbolic and emotional role within our societies has undergone profound transformations over time. The Oxford dictionary literally defines cemetery as ¿A large burial ground¿. The meaning in the American heritage dictionary is similar: ¿A place for burying the dead.¿ The definitions of cemetery in both dictionaries significantly mentions the dead and dark side of these spaces. Not only these definitions but also modern zoning legislation on cemeteries deny their role as urban open public green spaces and their potential to contribute to human well-being. Decisions about cemeteries segregation follow two-dimensional land-use urban planning, without considering their relationships with other urban spaces and without a real understanding of human behavior. The usual process of urban development treats cemeteries as isolated singular function urban spaces, not as part of larger urban fabrics. This vision leads to the appearance of urban spaces without any urban design qualities. This research was conceived to investigate the main process of urban cemeteries integration with cities and human daily life by biophilic approaches (based on Iran as a case study). It has the potential to make an important contribution to both academic research and planning decisions on the roles of urban cemeteries in cities and their response to human well-being. The thesis is based on two literature review parts concerning urban design assessment and biophilic applied methods. It highlights the necessity of intervention at different scales (urban planning, urban design, architecture, and landscape design) in order to develop an integration process of cemeteries. The case study of Tehran and references to international cases lead to address the general strategies and guides of this process in detail.

DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION

  • GARCIA LOPEZ, JAVIER: Geometric computer vision meets Deep Learning for autonomous driving applications
    Author: GARCIA LOPEZ, JAVIER
    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: 05/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: MORENO NOGUER, FRANCESC D'ASSIS | AGUDO MARTÍNEZ, ANTONIO
    Committee:
         PRESIDENT: VENTURA ROYO, CARLES
         SECRETARI: SÁNCHEZ RIERA, JORDI
         VOCAL: HERRANZ ARRIBAS, LUIS
    Thesis abstract: This dissertation intends to provide theoretical and practical contributions on the development of deep learning algorithms forautonomous driving applications. The research is motivated by the need of deep neural networks (DNNs) to get a fullunderstanding of the surrounding area and to be executed on real driving scenarios with real vehicles equipped with specifichardware, such as memory constrained (DSP or GPU platforms) or multiple optical sensors, which constraints the algorithm'sdevelopment forcing the designed deep networks to be accurate, with minimum number of operations and low memoryconsumption.The main objective of this thesis is, on one hand, the research in the actual limitations of DL-based algorithms that prevent themof being integrated in nowadays' ADAS (Autonomous Driving System) functionalities, and on the other hand, the design andimplementation of deep learning algorithms able to overcome such constraints to be applied on real autonomous drivingscenarios, enabling their integration in low memory hardware platforms and avoiding sensor redundancy. Deep learning (DL)applications have been widely exploited over the last years but have some weak points that need to be faced and overcame inorder to fully integrate DL into the development process of big manufacturers or automotive companies, like the time needed todesign, train and validate and optimal network for a specific application or the vast knowledge from the required experts to tunehyperparameters of predefined networks in order to make them executable in the target platform and to obtain the biggestadvantage of the hardware resources. During this thesis, we have addressed these topics and focused on the implementationsof breakthroughs that would help in the industrial integration of DL-based applications in the automobile industry.This work has been done as part of the "Doctorat Industrial" program, at the company FICOSA ADAS, and it is because of thepossibilities that developing this research at the company's facilities have brought to the author, that a direct impact of theachieved algorithms could be tested on real scenarios to proof their validity. Moreover, in this work, the author investigates deepin the automatic design of deep neural networks (DNN) based on state-of-the-art deep learning frameworks like NAS (neuralarchitecture search). As stated in this work, one of the identified barriers of deep learning technology in nowadays automobilecompanies is the difficulty of developing light and accurate networks that could be integrated in small system on chips (SoC) orDSP. To overcome this constraint, the author proposes a framework named E-DNAS for the automatic design, training andvalidation of deep neural networks to perform image classification tasks and run on resource-limited hardware platforms. Thisapporach have been validated on a real system on chip by the company Texas Instrumets (tda2x) provided by the company,whose results are published within this thesis. As an extension of the mentioned E-DNAS, in the last chapter of this work theauthor presents a framework based on NAS valid for detecting objects whose main contribution is a learnable and fast way offinding object proposals on images that, on a second step, will be classified into one of the labeled classes.

DOCTORAL DEGREE IN CHEMICAL PROCESS ENGINEERING

  • ABDELALEEM TAHA ZIED, AHMED SHOKRY: A contribution to chemical process operation support: new machine learning and surrogate models based approaches for process optimization, supervision and control
    Author: ABDELALEEM TAHA ZIED, AHMED SHOKRY
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN CHEMICAL PROCESS ENGINEERING
    Department: Department of Chemical Engineering (EQ)
    Mode: Normal
    Deposit date: 05/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: ESPUÑA CAMARASA, ANTONIO
    Committee:
         PRESIDENT: MOULINES, ERIC FRANÇOIS VICTOR
         SECRETARI: GUILLEN GOSALBEZ, GONZALO
         VOCAL: ZIO, ENRICO
    Thesis abstract: In the chemical process industry, the decision-making hierarchy is inherently model-based. The scale and complexity of the considered models (e.g., enterprise, plant or unit model) depend on the decision-making level (e.g., supply-chainmanagement, planning, scheduling, operation) and the allowable time slot (weeks, hours, seconds) within which model simulation runs must be performed and their output is analyzed to support the decision making. The use of high-fidelity models, which include detailed physics-based description of the process, is attracting wide interests of the processengineers. Since, these First Principle Model (FPMs) are able to accurately predict the real behavior of the process, leading to realistic optimal decisions. However, their use is hindered by practical challenges as the high computational time required for their simulation and the unguaranteed reliability of their consistent convergence. The challenges become prohibitive at lower levels of the decision-making hierarchy (i.e., operation), where decisions are required online within time slots ofminutes or seconds entailing lots of simulation runs using such complex and highly nonlinear FPMs. Surrogate modelling techniques are potential solution for these challenges, which relies on developing simplified, but accurate, data-driven or machine learning models using data generated by a FPM simulations, or collected from a real process. Although, there areprogressive developments of surrogate-based methods in the chemical engineering area, they are concentrated in process design and steady-state optimization areas.This Thesis presents a framework for the proper and effective use of surrogate models and machine learning techniques in different phases of the process operation. The objective is to provide efficient methodologies, each supports the decisionmaking in a specific phase of the process operation, namely; steady-state operation optimization, Model Predictive Control (MPC), multivariate system identification and multistep-ahead predictions, dynamic optimization, Fault Detection and Diagnosis (FDD) and soft-sensing. Each developed methodology is designated according to careful State-Of-Art (SOA) review that identifies the gaps and missing requirements to be covered. The SOA, identified gaps and the contributions of each methodology are summarized in Chapter 1 and detailed in the introduction of each of the following chapters.In this context, Chapter 3 presents a surrogate-based methodology for steady-state operation optimization of complex nonlinear chemical processes modelled by black-box functions. Chapter 4 proposes machine learning-basedmethodologies for multiparametric solution of complex operation optimization problems subjected to uncertainty. Chapter 5 presents a data-based multiparametric MPC methodology that enables simple implementations of explicit MPC for nonlinear chemical processes. Chapter 6 proposes a data-driven methodology for multivariate dynamic modelling of nonlinearchemical processes and for multistep-ahead prediction. Chapter 7 suggests a dynamic optimization methodology for solving optimal control problems of complex nonlinear processes based on data-driven dynamic models. Chapter 8 shows a hybrid methodology to improve FDD of chemical processes run under time-varying inputs based on multivariate data-drivendynamic models and classification techniques. Chapter 9 presents data-driven soft-sensing methodologies for batch processes operated under changeable initial conditions. The effectiveness of the developed methodologies is proved by comparing their performances to those of classical solution procedures existing in the SOA, via their applications to different benchmark examples and case studies. The promising results and their sound analysis allowed to publish many papers in top-ranked journals and proceedings, and to present them at several top-ranked international conferences including two Keynote presentations.

DOCTORAL DEGREE IN COMPUTATIONAL AND APPLIED PHYSICS

  • AZNAR LUQUE, ARACELI: Barocaloric effects at first-order phase transitions
    Author: AZNAR LUQUE, ARACELI
    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 Applied Physics (FA)
    Mode: Temporary seizure
    Deposit date: 24/02/2021
    Reading date: 15/04/2021
    Reading time: 11:00
    Reading place: Aula 1.6 Edifici A. EEBE - UPC DIAGONAL-BESÒS - videoconferencia: https://meet.google.com/xdg-tuvk-tjg
    Thesis director: LLOVERAS MUNTANE, POL MARCEL | TAMARIT MUR, JOSE LUIS
    Committee:
         PRESIDENT: VIVES SANTA EULÀLIA, EDUARD
         SECRETARI: MACOVEZ, ROBERTO
         VOCAL: GONZALEZ SILVEIRA, MARTA
    Thesis abstract: Current refrigeration devices, based on vapour-compression cycles, employ refrigerants such as HFCs, which exhibit a global warming potential a thousand times higher than the one produced by CO2,. Furthermore, the increasing middle class, associated with their refrigeration needs, urges for research in new environmentally friendly refrigerant alternatives.Solid-state caloric effects have been proposed as potential alternatives to replace the vapour-compression refrigeration technologies. They may become giant under the cyclic application and removal of an external field which induces changes in entropy and temperature associated with the occurrence of a first-order phase transition. In this work we specifically focus on caloric effects driven by means of hydrostatic pressure (barocaloric effects, BCEs), which allow us to operate with powder compounds, avoiding fatigue upon cycling. Additionally, a wide variety of materials can be used with BC purposes, due to the possibility of working with powdered samples and to the emergence of BCE associated with any transition volume change.In this dissertation we carried out the study of the BC performance of a series of compounds belonging to four different material families: Plastic crystals (PC), hybrid organic-inorganic perovskites (HOIPs), magnetic alloys and a superionic conductor. The election of these materials is not arbitrary, but relies on several features which anticipate good BCEs, such as large transition entropy changes, pressure sensitivity of the transition temperature and small thermal hysteresis. The small hysteresis avoids losses related with the refrigeration cycle and ensures smaller pressures under which reversibility is observed (which at the same time enable smaller applied work to the refrigerant). Finally, other properties must also be taken into account when designing a refrigeration device: Density, thermal conductivity and costs of production. BCEs are determined by means of a combination of quasi-direct and indirect methods. Firstly, we conduct measurements of atmospheric pressure and high-pressure calorimetry (DSC and DTA, respectively), along with experiments of X-ray diffraction and dilatometry. Then, the isobaric entropy curves are constructed, from which by means of curves subtraction the BCEs can be obtained. Additionally, special attention has been put on reversibility, since cyclability is mandatory for a real refrigeration device. Among the family of PC, derivatives from adamantane (1- and 2-adamantanol) and neopentane (neopentylglycol, neopentyl alcohol, pentaglycerine, tris(hydroxymethyl)aminomethane and 2-amino-2-methyl-1,3-propanediol) have been studied. Results for reversible isothermal entropy changes reach colossal values between 300-500 JK-1kg-1 and 150-500 JK-1kg-1 for neopentane and adamantane derivatives, respectively. These values are associated with adiabatic temperature changes among 10-20 K for pressure changes of ~2.5 kbar.The studied HOIPs ([TMA](Mn(N3)3) and [TMA]2(NaFe(N3)6)) exhibit giant values of ~100 J K-1 kg-1 with temperature changes between 15-20 K for pressure changes of ~2 kbar. It is important to highlight the small pressure required in order to obtain reversibility for these compounds, which is about only ~0.1 kbar.Magnetic alloys MnCoGeB0.03, Mn3NiN, Mn3(Zn0.45In0.55)N and Ni50Mn31.5Ti18.5 have been analysed. Nonetheless, only MnCoGeB0.03 and Mn3(Zn0.45In0.55)N show reversibility. They exhibit ~25 J K-1 kg-1 and 4-10 K under pressure changes of ~3 kbar.Finally, AgI, the only superionic conductor studied in this dissertation, reaches ~50 J K-1 kg-1 and ~10 K under pressure changes of 2 kbar. These results become the most outstanding presented in this thesis when normalized by volume.Finally, several figures of merit are presented, in which the studied materials are put into comparison with each other and with other already reported compounds.
  • CASTRILLON CAMACHO, ARJUNA: Estudio de las propiedades fisicas en regiones chocadas en nebulosas planetarias.
    Author: CASTRILLON CAMACHO, ARJUNA
    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: 24/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: JOSE PONT, JORDI | GARCÍA SENZ, DOMINGO
    Committee:
         PRESIDENT: DOMINGUEZ AGUILERA, MARIA INMACULADA
         SECRETARI: SALA CLADELLAS, GLÒRIA
         VOCAL: TRIGO RODRIGUEZ, JOSEP MARIA
    Thesis abstract: Planetary nebulae play a very important role in the chemical evolution of galaxies since they are responsible for returning nuclear-processed material to the interstellar medium. Observations of planetary nebulae are used to determine the chemical abundances present in the interstellar medium and in all galaxies.In this study, the properties and characteristics of the small-scale structures present in planetary nebulae are analyzed. The aim of this work is to understand the evolutionary fate of low and intermediate mass stars. Specifically, this work focuses on the study of episodes known as "jets", which are ejected by the central star of the planetary nebula. The presence of collimated bipolar fluxes and point-symmetry morphologies are commonly observed in planetary nebulae, but the physics of such structures is not yet well understood. With this thesis we want to determine the observational properties of some structures present in planetary nebulae, known as FLIER's/LlS (Fast Low Ionization Emission Regions [FLIERsl and Low Ionization Structures [LIS]).In a first phase, the morphology of a sample of planetary nebulae selected from the HST (Hubble Space Telescope) database is analyzed by applying anisotropic wavelet analysis. Through this analysis, we determined: first, the spatial distribution of the structures of interest (FLIERs/LlS) and their characteristic sizes; second, spectroscopic data with two-dimensional coverage of our sample are obtained. With these data, we can draw maps of physical conditions, such as the excitation and the ionization structure in bow shocks. Through these maps we can show the effects of photoionization due to heating caused by the central star in the areas known as irradiated shocks.All the analyses carried out on the planetary nebulae considered in this work yield conclusive results on the presence of microstructures. The abrupt changes evidenced in the ratios studied (10 Ill]/Ha, [N Il]/Ha) are a clear indication of the presence of microstructures in the regions of irradiated shocks. From the wavelet analysis, the presence of "knots", "jets", "jet-like" and filaments is evidenced in each of the nebulae considered. Additionally, the one-dimensional profiles present a slight spatial shift in each of the spectral lines considered (10 Ill], [N Il], and Ha), which indicates that the structures are symmetrically located with respect to the central star.From the analysis of the protoplanetary nebula CR 618, the movements of the lobes measured in two different time periods are quantified. From this, the parameters of the simulation using the hydrodynamic code created by Raga (2000) are set. We obtained encouraging results in the study of this nebula, allowing us to give an explanation to the proper motions and the morphology of the lobes from the well-collimated bipolar ejection and the precession in the axis of their flow.
  • CIKOJEVI¿, VIKTOR: Ab-initio quantum Monte Carlo study of ultracold atomic mixtures
    Author: CIKOJEVI¿, VIKTOR
    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: Change of supervisor
    Deposit date: 26/02/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: BORONAT MEDICO, JORDI | VRANJES MARKIC, LEANDRA
    Committee:
         PRESIDENT: BULJAN, HRVOJE
         SECRETARI: MASSIGNAN, PIETRO ALBERTO
         VOCAL: SANTOS SANCHEZ, LUIS
    Thesis abstract: The properties of mixtures of Bose-Einstein condensates at T=0 have been investigated using quantum Monte Carlo (QMC) methods and Density Functional Theory (DFT) with the aim of understanding physics beyond the mean-field theory in Bose-Bose mixtures. In particular, quantum liquid droplets with attractive intraspecies and repulsive interspecies attraction were studied, for which we observed significant contributions beyond Lee Huang Yang (LHY) theory that affect the energy, saturation density, and surface tension. The critical atom number in droplets in free space for total number of atoms N between N=30 and N=2000 was obtained. Results of the surface tension for three values of the attractive interspecies interactions are presented. For a homogeneous system, extensive calculations of the equations of state were performed and we report the influence of finite-range effects in beyond-Bogoliubov theory. In systems interacting with a small (large) effective range, we observe repulsive (attractive) beyond-LHY contributions to the energy. For the droplets in a mixture of 39K atoms, which were observed experimentally for the first time, the calculations of equations of state were performed. Combining QMC-built functionals with DFT, the discrepancy in the estimation of critical atom number between the mean-field theory and experimental results was explained by the proper inclusion of the effective range in inter-particle interaction models. The influence of finite-range effects on breathing and quadrupole modes in 39K quantum droplets was investigated. We predicted a significant deviation in the excitation frequencies when entering a more correlated regime. Finally, the phase diagram of repulsive Bose-Bose mixtures in a spherical harmonic trap using Quantum Monte Carlo calculations was studied. Density profiles were obtained reported and we found the occurrence of three phases: separation of condensates in two blobs, fully mixed and shell-separated phase. A comparison with the Gross-Pitaevskii solutions showed a large deviation in the regime of large mass imbalance and strong interactions. We showed the universality in the density profiles with respect to the s-wave scattering length and found numerical evidence for Gross-Pitaevskii scaling present beyond the regime of applicability of Gross-Pitaevskii equations.

DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING

  • ANITORI, GIORGIO: Risk-based highway bridge inspection intervals
    Author: ANITORI, GIORGIO
    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: 25/02/2021
    Reading date: 23/04/2021
    Reading time: 12:00
    Reading place: AULA 002 Edifici C1 Escola de Camins - UPC CAMPUS NORD - C/ Jordi Girona, 1, 3, 08034
    Thesis director: CASAS RIUS, JUAN RAMON
    Committee:
         PRESIDENT: RAMOS SCHNEIDER, GONZALO
         SECRETARI: SILVA CARVALHO CAMPOS MATOS, JOSE ANTONIO
         VOCAL: TANNER, PETER
    Thesis abstract: Infrastructure maintenance programs establish schedules for routine inspections of highway bridges with little consideration of their current conditions. The time interval between two inspections is traditionally set based on experience and on engineering judgment. For example, in the US considerable expenditures are incurred to meet the required biennial routine inspection of all bridges many of which may be in good condition. It is therefore of great interest for the engineering community to develop an approach to control inspection schedules of individual bridges and minimize their associated costs using rational criteria that account for the lower risk of postponing the inspection of bridges that are subject to reduced deterioration mechanisms and low traffic loadings. The implementation of such a risk-based approach would go a long way in helping optimize the limited resources available for maintaining the vast highway infrastructure system. The object of this Ph.D. dissertation is to develop a rational approach for determining a risk-based optimum time interval between bridge inspections. The proposed theoretical approach subsequently serves for proposing a simple procedure that is implementable in routine practice by bridge engineers using easily available bridge-specific data.To illustrate the proposed procedure using actual bridge data, the work uses highway data from the state of New York (NYS) in the United States of America (USA) in the form of Weigh-in-Motion (WIM) truck traffic data and bridge records provided through the National Bridge Inventory (NBI) database. These data are used to develop a theoretical framework able to define the capacity of bridges probabilistically and the risk of bridge failure if a bridge¿s inspection is deferred for a limited period of time.The calculations performed in this dissertation based on data collected in the state of New York are limited to simple span composite steel-concrete superstructures that constitute a large proportion of short to medium span bridges in North America. However, the same concepts can be extended to other types of superstructures and other regions of the world as appropriate data become available.The conclusions of this study include the demonstration of the inadequacy of utilizing a standard two-year inspection interval for all bridges. To overcome this problem a simplified procedure is proposed for an easy practical engineers¿ application.

DOCTORAL DEGREE IN EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS

  • MONTALBAN TURON, CARLOS: Análisis estructural de escaleras para edificios frente a viento y sismo
    Author: MONTALBAN TURON, 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 EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS
    Department: (DECA)
    Mode: Normal
    Deposit date: 14/01/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: BRUFAU NIUBÓ, ROBERTO | GONZALEZ DRIGO, JOSE RAMON
    Committee:
         PRESIDENT: MAÑA REIXACH, FRUCTUOSO
         SECRETARI: MARTÍN SÁIZ, RODRIGO
         VOCAL: DE SOUSA CRUZ, PAULO JORGE
    Thesis abstract: In this PhD Dissertation the structural performance of buildings with stairs submitted to lateral loads, is investigated. Because of the historical neglect of the interaction effects between the main structure and stairs, in professional and scientific practices, the objective is to address the current uncertainty regarding the structural safety of the evacuation exits of buildings, when they face seismic threats. For this reason, solutions are investigated in search of the optimal interaction between the main structure and the stairs. Currently, the project of buildings with stairs is controlled by different types of regulations, to ensure that, in an accidental situation, the stairs are the safest place and route to evacuate the building. However, in front of seismic threats, it is recommended not to stay in areas of the building with stairs, because it has been proven that they are elements highly vulnerable to the effects of the earthquake. The criteria for fire safety and against seismic threats are contradictory. Therefore, the need to rethink the way of designing stairs as well as their interaction with the building structure is confirmed. In an accidental situation (be it due to fire or to earthquake), the integrity of the staircase is essential to ensure a rapid evacuation of and adequate assistance to the users of the building and, for this reason, the structural safety of the evacuation routes should be guaranteed, in front of any accidental situation. In this research, four three dimensions (3D) models have been defined and, in each one of them, a non-linear static analysis has been performed against incremental pushes in the two main directions, which involves eight pushover analyses. Two analysis models correspond to the usual way of analyzing seismic behavior today, that is, without considering the structural presence of the stairs in the calculation model. The other two propose two different stair solutions, which, in these cases, have been modeled as part of the main structure. The research is carried out through three different fields of knowledge, the coordination of which has made it possible to solve a problem of international concern that each year causes the loss of hundreds of humans¿ lives, serious accidents and significant material damage, on all continents of the world. The three main areas of knowledge are: 1) architecture, 2) steel building engineer-ing, and 3) the study of seismic behavior (earthquake engineering). The contribution of this thesis to the problem of the fragility of the stairs could hardly have been made from the specialization in a single area of the three mentioned ones. Through the development, some preestablished impositions in each field of study are questioned and overcome: 1) the function of stairs in architecture, 2) the reason for the bracing system and the external actions that actually act on them and 3) the determining incidence of the stairs on the overall dynamic and seismic behavior of the building (structural dynamics and seis-mology). The main contribution is to offer, for the first time, an architecture project that provides a transversal solution to the three areas of study. Starting from Le Corbusier's definition, "... architecture is the wise, correct and magnificent game of volumes organized under light¿." Here, the parallelism could be nuanced: "... and of the organized masses in the face of acceleration". The scope of this thesis has been to design buildings in which the main structure and the stairs constitute an effective structural type against the effects of vertical (gravity) and horizontal (wind or earthquake) acceleration loads. The results obtained prove that the integration of the essential elements of the architecture (the main structure and the stairs, in this case) allows creating new, safer, more economical and resilient structural types.

DOCTORAL DEGREE IN ENVIRONMENTAL ENGINEERING

  • LI, JUN: Selenium and zinc enriched bioproducts generated from wastewater as micronutrient feed supplements and biofertilizers
    Author: LI, JUN
    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: Change of supervisor
    Deposit date: 18/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: FERRER MARTI, IVET | DU LAING, GIJS
    Committee:
         PRESIDENT: DE SMET, STEFAAN
         SECRETARI: ROUSSEAU, DIEDERIK
         VOCAL NO PRESENCIAL: LIANG, DONGLI
    Thesis abstract: This thesis aimed to explore the potential of Se/Zn-enriched bioproducts produced from wastewater treatment processes by eco-technologies (phytoextraction, bioreduction and microalgae-based systems) as Se/Zn feed supplements and biofertilizers.In the first part, two aquatic plants (Lemna and Azolla) with substantial protein content were applied to evaluate the possibility of Se and Zn bioaccumulation/removal from wastewater while producing micronutrient-enriched dietary proteins (for feed/food supplements) and biofertilizers. High transformation to organic Se forms and accumulation in plants after taking up Se(IV), together with the high protein content and fast growth rate, makes Lemna (also named duckweed later on) and Azolla good candidates for the production of Se- and Zn-enriched biomass, which can be used as crop fertilizers or protein-rich food/feed supplements or ingredients. The second and third parts, respectively, evaluated the valorization potential of the produced micronutrient-enriched duckweed as well as sludge generated in wastewater treatment processes containing single Se or Se combined with Zn as micronutrient biofertilizers. Micronutrient-enriched sludge dominated by the presence of Se in zero oxidation state (Se(0)) was found to be the preferred slow-release Se biofertilizer and an effective Se source to produce Se-enriched beans for Se-deficient populations, as compared to micronutrient-enriched duckweed. On the contrary, the Zn content in the seeds of beans was not successfully improved through the application of micronutrient-enriched biofertilizers in comparison with the control. This could be attributed to the lower Zn amount applied into soils as Se/Zn-enriched biomaterials. The following experiment explored the potential of Se removal in high rate algae ponds (HRAPs) treating domestic wastewater, while producing high-value Se-enriched biomass. Results indicated that the wastewater treatment performance of the HRAPs was effective. The produced Se-enriched microalgae in HRAPs fed with domestic wastewater contained a high content of crude protein (48% of volatile suspended solids), the selenoamino acid selenomethionine (SeMet) (91% of total Se), and the essential amino acid. The production of Se-enriched microalgae in HRAPs may offer a promising alternative for upgrading low-value recovered resources into high-value feed supplements. The last experiment aimed to evaluate the Se-enriched microalgae generated in the previous experiment as a potential biostimulant to enhance plant growth and as a Se biofertilizer to improve the Se content of plants. This study demonstrated that the application of raw Se-enriched microalgae biomass to soil (1-10%, soil application) and its extracts to leaves (1%, foliar spray) enhanced plant growth, which confirmed that Se-enriched microalgae acts as a biostimulant. Besides, a higher Se content in the plant was achieved after the application of Se-enriched microalgae or extracts thereof. This indicated that Se-enriched microalgae can be valorized as a biostimulant and biofertilizer to improve both the seed yields and Se content of beans, leading to a higher market value of the beans.This thesis contributes to offering an environmentally friendly and sustainable way for micronutrient biofortification/ supplementation in Se/Zn-deficient areas, while recovering nutrients from wastewater.

DOCTORAL DEGREE IN GEOTECHNICAL ENGINEERING

  • BARBOZA DE VASCONCELOS, RAMON: A double-porosity formulation for the THM behaviour of bentonite-based materials
    Author: BARBOZA DE VASCONCELOS, RAMON
    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: 03/03/2021
    Reading date: 18/05/2021
    Reading time: 11:00
    Reading place: ETSCCPB - UPC Campus Nord - videoconferència: meet.google.com/fgm-vzzb-jem
    Thesis director: GENS SOLE, ANTONIO | VAUNAT, JEAN
    Committee:
         PRESIDENT: VILLAR GALICIA, MARÍA VICTORIA
         SECRETARI: PRAT CATALAN, PERE
         VOCAL NO PRESENCIAL: LLORET CABOT, MARTI
    Thesis abstract: The thermo-hydro-mechanical (THM) behaviour of expansive clays has been extensively studied in the last decades due to the potential use of bentonites as components of engineered barrier systems (EBS) in deep geological repositories for high-level and long-lived radioactive wastes. Since the early post closure period, the EBS is subjected to changes in temperature, moisture content and stresses due to the coupled THM processes expected to occur in such an environment. The different structural levels found in unsaturated expansive clays requires the use of constitutive models that considers the explicit distinction of these pore-structure levels in their mathematical formulation in order to reproduce the development of the fabric of bentonite materials subjected to the complex THM paths taking place during the lifetime of a nuclear waste repository. A coupled THM formulation that represents the expansive soil as two overlapped but distinct structural media has been developed in the framework of classical and generalized plasticity theories. In such a double-structure approach, the THM behaviour of the expansive soil is characterized by constitutive laws formulated to account for the relevant processes affecting each porous medium and for the interaction mechanisms relating the deformation and the saturation states of the active clay particles to the structural arrangement of the clay aggregates and to the water potential in the larger interconnected pores. In addition, the mechanical response of the porous medium to any THM loading is intrinsically related to the compressibility of the clay minerals. The irreversible changes in the soil fabric are attributed to the loading-collapse (LC) mechanism and to the micro-macro structural coupling (ß-mechanism). Thermal effects are incorporated into the mathematical formulation of the double structure model, which has been implemented in a finite element code (CODE_BRIGHT) able to solve, in a fully coupled way, the system of partial differential equations arising from the governing equations (balance equations). An explicit and robust integration scheme with automatic sub-stepping and error control has been employed to update the stress tensor and the internal (history) variables. The capabilities of the implemented double-porosity model to predict the expected response of expansive clays under isothermal and non-isothermal scenarios have been checked by the performance of constitutive analyses following a number of prescribed THM paths under confined and unconfined conditions. In addition, sensitivity analyses have been carried out in order to verify the dependence of the local expansive response on the initial conditions and on the sequence of load application. Special attention has been placed on the role played by the pore-water mass transfer between the two pore-structure levels in the development of the swelling potential of the expansive porous medium. The performance of the model in reproducing the actual THM behaviour of laboratory-scale tests has also been examined by means of the modelling of the hydration of two heated columns made of granular bentonite materials, selected as potential buffer materials in the construction of engineered barriers. The comparison between the available experimental data and the model results has shown the ability of the current double-porosity formulation to simulate the main observed features of the THM behaviour of the expansive material when subjected to complex loading paths.
  • TARRAGÓ MUNTÉ, DANIEL: Hydraulic fills liquefaction. Effect on quay stability
    Author: TARRAGÓ MUNTÉ, 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 GEOTECHNICAL ENGINEERING
    Department: (DECA)
    Mode: Normal
    Deposit date: 24/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: GENS SOLE, ANTONIO | ALONSO PEREZ DE AGREDA, EDUARDO
    Committee:
         PRESIDENT: GONZALEZ GALINDO, JESUS
         SECRETARI: ARROYO ALVAREZ DE TOLEDO, MARCOS
         VOCAL NO PRESENCIAL: PINEDA, JUBERT
    Thesis abstract: The starting point of this thesis is the failure of part of a quay wall under construction. The quay was divided in two phases, failure affected Phase 1 only. The failure and all the relevant associated information on quay design, construction and monitoring records are described in detail together with the results of a site investigation campaign carried out after the failure. Flow liquefaction of the hydraulic fill emplaced behind the quay wall was the main cause of the failure. The state of the hydraulic fill in the quay area is assessed in the light of the current understanding of the phenomenon and of a number of flow liquefaction criteria. In addition, an elastoplastic constitutive law is described that is capable to simulate the undrained brittleness behaviour that underlies the phenomenon of flow liquefaction. It is a critical-state model that incorporates the concept of state parameter. Subsequent finite element analyses are able to reproduce satisfactorily the behaviour of the quay during construction and the features and circumstances of the failure. Two possible triggering mechanisms are identified that can explain the failure: spontaneous liquefaction, or liquefaction of a limited zone caused by the concurrent construction of an embankment. A parametric study verifies the robustness of the simulation and the dependence of stability on the degree of brittleness of the hydraulic fill. The same type of analysis of quay Phase 2, not involved in the failure, revealed that the margin of safety was small if the hydraulic fill liquefied. Soil improvement measures were implemented and an extensive monitoring system was installed. Construction of quay Phase 2 was completed applying the observational method that involved a continuous check of the monitoring data and its comparison with numerical simulation results. An additional site investigation confirmed that the soil improvement measures had succeeded in removing both the flow and the cyclic liquefaction potential of the hydraulic fill, according to currently accepted criteria. The Phase 1 quay involved in the failure was reconstructed with mainly terrestrial fill with no flow potential liquefaction, as confirmed by the corresponding site investigation. Based on the experience gathered in the case and on the research carried out, an operational scheme dealing with quays constructed with hydraulic fills susceptible to flow liquefaction is proposed. It consists of a protocol to evaluate liquefaction potential of hydraulic fills, the use of a constitutive law capable of simulating flow liquefaction, the implementation of soil improvement measures to reduce flow liquefaction potential and the employment of a monitoring system to control the quay wall behaviour during construction and to provide data for comparison with numerical analyses results.

DOCTORAL DEGREE IN MARINE SCIENCES

  • CALDERON VEGA, FELICITAS: Probabilistic characterization of single and concurrent metocean variables of Mexican coasts with seasonal variability using extreme value theory, with application to reliability of coastal structures.
    Author: CALDERON VEGA, FELICITAS
    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: Article-based thesis
    Deposit date: 16/03/2021
    Reading date: 20/04/2021
    Reading time: 17:00
    Reading place: Escola de Camins - UPC Campus Nord - enllaç públic: https://meet.google.com/yzf-nrnb-qco
    Thesis director: GARCÍA SOTO, ADRIAN DAVID | MÖSSO ARANDA, OCTAVIO CESAR
    Committee:
         PRESIDENT: OCAMPO TORRES, FRANCISCO JAVIER
         SECRETARI: SANCHEZ-ARCILLA CONEJO, AGUSTIN
         VOCAL NO PRESENCIAL: FERRER RODRÍGUEZ, LUIS
    Thesis abstract: This thesis encompasses a set of different subjects related to metocean variables but studied from different perspectives. The metocean variables are mainly significant wave heights and wind velocities and, to a lesser extent, wave periods. The extreme value theory is used to probabilistically characterized the metocean variables by means of the generalized extreme value distribution (GEV). The effect of seasonality is included by considering monthly maxima and using harmonic and subharmonic functions (i.e., time dependency in the GEV model is incorporated). Although Mexican information was not available to this study, the studies are considered applicable to Mexican coasts in the Gulf of Mexico and the Pacific, since available public information from U.S. buoys located in the Atlantic and Pacific oceans relatively close to the Mexican coasts is employed. For the Pacific region, the GEV model accounting for seasonality is applied to data from a buoy (this is reported in an article in the appendix and summarized as a book chapter in the compendium of publications) and comparisons are carried out versus analogous results for buoys in the Gulf of Mexico obtained in a previous study (included also in the appendix). In other part of the thesis (another book chapter in the compendium), but also for the buoy in the Pacific Ocean, a study is carried out to assess the impact of including or excluding an atypical wave height in the seasonality and in future projections (i.e., wave heights associated with given return periods), since an atypically large significant wave heigh was observed for the considered buoy. One more study (an article in the compendium) introduces the wind velocity as a Metocean variable to be characterized with the time-dependent GEV model from data of a buoy in the Gulf of Mexico. This wind velocity is not for monthly maxima, but for the recorded wind velocity which simultaneously occurred with the maximum significant wave heights. This allowed to propose a simplified approach to determined concurrent significant wave heights and associated wind velocities for given return periods, while accounting for seasonality and quantitatively establishing the uncertainty in the correlated metocean variables in question. This proposal can be potentially used for design and engineering purposes, if the metocean are considered as hazards which imposed demands on coastal (and structural) engineering systems. Additionally, the effect of varying the considered time window for the extreme projections is explored. In a final study (also an article in the compendium), an introduction to the reliability of coastal (and also structural) engineering systems is presented; a breakwater is used as case-study. The coastal structure is subjected to the action of wave heights with different wave periods, for which the joint Longuet-Higgins distribution is used, and the overtopping probability of failure is computed by using classical and revisited reliability approaches. Future studies could combine the characterization of metocean variables as time-dependent GEV models and the used reliability approaches to further investigate the reliability of coastal and offshore systems.

DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING

  • BESHARATLOO, HOSSEIN: Micromechanical properties of inorganic multiphase materials
    Author: BESHARATLOO, HOSSEIN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
    Department: (CEM)
    Mode: Article-based thesis
    Deposit date: 03/03/2021
    Reading date: 13/05/2021
    Reading time: 11:00
    Reading place: Escola d'Enginyeria de Barcelona Est - Campus Diagonal-Besòs - videoconferència: https://meet.google.com/yvk-ugwq-gup
    Thesis director: LLANES PITARCH, LUIS MIGUEL | ROA ROVIRA, JOAN JOSEP
    Committee:
         PRESIDENT: RINALDI, ANTONIO
         SECRETARI: JIMENEZ PIQUÉ, EMILIO
         VOCAL: MSAOUBI, RACHID
    Thesis abstract: This thesis is dedicated to understanding the micromechanical properties of multiphase materials which are indispensable in today¿s engineering applications. The mechanical behavior of these materials is dictated by the intrinsic response of each constitutive phase as well as the fashion in which they interact with each other. Therefore, an accurate assessment of both microstructural characteristics and small-scale mechanical properties becomes key for understanding the macroscopic behavior of these materials.Within the above context, the current study is intended to offer a systematic investigation, aiming to assess small-scale mechanical properties of multiphase materials through a protocol based on massive nanoindentation and statistical analysis. It consists of three sequential stages: (1) microstructural characterization, (2) micromechanical evaluation (massive indentation and statistical analysis), (3) correlation between microstructure and mechanical properties using advanced characterization techniques.Microstructural characterization of studied systems was carried out through extensive field emission scanning electron microscopy analysis. This is an essential step for determining testing parameters to be used when implementing massive indentation, particularly penetration depth of performed imprints. Based on the acquired information, massive indentation testing and statistical analysis of experimentally gathered data were implemented to determine the local properties of several unidentified phases. Such data analysis was then complemented by the use of different advanced characterization techniques for deeper inspection of microstructural features. Main goal of this final step was to define the unidentified mechanically distinct phases, based on physically- based correlations between microstructure features and small-scale properties.The proposed and described protocol has been implemented on three different materials: Duplex Stainless Steels (DSS), Polycrystalline cubic Boron Nitride (PcBN) composite and Ti(C,N)-FeNi cermets. They are representative of metal-metal, ceramic- ceramic, and ceramic-metal systems, respectively.Regarding DSS, the influence of the processing route on the local mechanical properties (hardness (H) and elastic modulus (E)) of ¿ and a phases of a DSS was successfully evaluated. Moreover, a novel 2D histogram of hardness and elastic modulus was introduced and validated as an effective tool to correlate microstructure and intrinsic mechanical properties of the constitutive phases of DSSs.PcBN composite consists of cBN particles embedded within a TiN binder. The correlation of relative B/N ratio and local hardness for individual cBN particles was studied, through complementary analysis using electron probe X-ray microanalysis of the data attained using the proposed methodology.The influence of ceramic/metal phase ratio and C addition on the local hardness of Ti(C,N)¿FeNi cermets have been assessed. Regarding the small-scale properties of the constitutive phases, the intrinsic hardness of both Ti(C,N) particles and FeNi binder were determined using the suggested testing procedure.It has been proven that the proposed methodology can be considered as a successful testing protocol for determining small-scale mechanical properties (H and E) of the studied multiphase systems. Nevertheless, successful implementation requires careful consideration of testing parameters used, based on microstructural, residual imprint, and plastic flow length scales.
  • KAMRANI MOGHADAM, MOHAMMAD REZA: Preparation and characterization of reactive extrusion modified PLA/ABS blends and its foams
    Author: KAMRANI MOGHADAM, MOHAMMAD REZA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN MATERIALS SCIENCE AND ENGINEERING
    Department: (CEM)
    Mode: Normal
    Deposit date: 23/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: SANCHEZ SOTO, MIGUEL ANGEL | CAILLOUX, JONATHAN
    Committee:
         PRESIDENT: LÓPEZ MARTÍNEZ, JUAN
         SECRETARI: MASPOCH RULDUA, MARIA LLUÏSA
         VOCAL: CASTILLO LÓPEZ, GERMAN
    Thesis abstract: The current thesis takes place within the context of the projects MAT2016-80045-R "Aplicaciones industriales de compuestos y mezclas basados en REX-PLA" and the project "PLAIABS Blends: Recydability and weight reduction" financially supported by the Ministerio de Economía y Competitividad of the Spanis h Government and SEAT res pectively.The main objective was to improve the properties of poly lactic acid (PLA) in arder to make it suitable for long-lasting applications where emphasis is de\Qted to the reduction of carbon dioxide emissions and the renewable raw materiaIs content. Among the different routes to enhance PLA properties, blending was used, as it is easily scalable bythe industry. Dueto its good balance of properties, ABS was considered a suitable polymer to be used together with PLA However, dueto their immiscibili ty, a coupling agent (ABS-g -MAH) was introduced.Apart of brittl ness, another PLA problem is its relatively easy degradation during process ing. Previous studies of the Group indicated that PLAdegradation could be limited using a multi epoxide reactive agent that a110ids the loss in molecular weight and increases the PLA melt visc osity, which, on the other hand, facilitates processing . Moreover, it was believed that the unreacted chain extender epoxide groups could also form covalent bonding with the coupling agent improving ABS and PLA compatibility.Using foams both the total weight and carbon dioxide generation of components can be diminished. For these reasons, different techniques for physicallyfoaming the blends either during injection (MuCell) or through a batch process were object of research. The effect of the above mentioned chain extender and the effect of a tale filler on the batch-foaming behavior of PLAwas studied.The first step of the research consisted in obtained the base materiaIs by reactive extrusion (REX) at a pilot plant seale (50 kg.). A conventional injection molding process was then employed to obtain standard samples that were used for the thermo­ mechanical characterization ofthe blends.The thermal stabilitywas studied bythe Kissinger 's method. The results showed that it was improved when the amount of ABS-g-MAH was increased. From the DSC analysis, it was found that in comparison to more perfect REX-PLA structures, crystals with a smaller lamellar thickness were formed in the blends. The differences in crystallinitywere small and do not influence the mechanical properties. The presence of ABS in the compositions led to a decrease ofthe blend 's storage modulus. Nonetheless, the ABS phase was found to playthe role of scaffold for the PLA phase that can undergo re­ crystallization, being thus able to support a certain amount of loading during heating.The physical foaming ofthe different injected blends was difficult to be achieved. The optimization ofthe foaming conditions required several triaIs and a large quantityof material. As the amount of each blend was limited, only a partial number of the proposed experiments were possible. The obtained blends contained a few large cells as well as a certain population of small sized cells. Although a complete micro-cellular structure was not achieved, the obtained one was similar to that of previous works found in literature. lt was, however, demonstrated that this technique can be used byindustryto generate lighter components.Batch foaming using CO2 in supercritical conditions resulted in successful foams with cell sizes below 100 microns and very high cell densi ties. In comparison to PLA, dueto its higher viscosity and melt resistance, using REX-PLA resulted in improved level offoaming which prevents from cell coalescence and collapse. The presence of ABS in the blends allowed broadening the range of pressure and temperatures in which foams can be produced. Tale was found to actas a nucleating agent leading to smaller cell sizes and higher cell densities in the foamed blends.

DOCTORAL DEGREE IN MECHANICAL, FLUIDS AND AEROSPACE ENGINEERING

  • REINA GUZMÁN, WASHINGTON SALVATORE: Contribución a la metodología de caracterización dinámica de materiales resilientes para aplicaciones ferroviarias
    Author: REINA GUZMÁN, WASHINGTON SALVATORE
    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 Mechanical Engineering (EM)
    Mode: Normal
    Deposit date: 11/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: ARCOS VILLAMARÍN, ROBERT | CLOT RAZQUIN, ARNAU
    Committee:
         PRESIDENT: CARRASCAL VAQUERO, ISIDRO ALFONSO
         SECRETARI: PÀMIES GÓMEZ, TERESA
         VOCAL: DE ARCAS CASTRO, GUILLERMO
    Thesis abstract: This thesis is focused on the enhancement and development of advanced methodologies for the dynamic characterisation of resilient elements used in railway applications. On the one hand, this thesis proposes several improvements to the application of the indirect method described in ISO 10846 standard for determining the dynamic stiffness of resilient elements using a swept-sine excitation. Within this framework, this work proposes a method that allows to design the swept-sine excitation parameters in order to ensure a predefined maximum error of those estimated frequency response functions that are needed to determine the dynamic stiffness. This method is based on a procedure that uses a numerical simulation of the test-rig and the resilient element of study which allows to predict the error made as a function of the excitation parameters and of the existing background noise, allowing to optimise the test in terms of required time and results quality. The method is then validated experimentally for two case studies: a sample of an elastomeric material and a coil spring. This work has also studied the influence that the experimental setup, the static preload and the dynamic loading have on the estimation of the frequency response functions. On the other hand, this thesis considers the adaptation of an existing in situ methodology to laboratory testing. The methodology allows to determine the dynamic stiffness of an elastic element in a broad frequency range with a single test. This alternative methodology has been validated using the two case studies previously mentioned. By including the improvements made to the indirect method to this methodology, it is possible to obtain a simple and robust method that can take into account the uncertainty related to several effects such as the excitation, the background noise and the experimental setup. Finally, the dynamic stiffness results obtained for both case studies have been compared to the results obtained using standardised methods such as the direct and indirect methods. From these comparisons it can be concluded that the proposed alternative method is the best choice to determine the frequency dependence of the dynamic stiffness, specially at high frequencies, as it allows to perform a broad-band characterisation in a single test and it overcomes the problems induced by the inertia forces found when the direct method is applied at high frequencies.
  • SARABANDI, SOHEIL: Solving the Nearest Rotation Matrix Problem in Three and Four Dimensions with Applications in Robotics
    Author: SARABANDI, SOHEIL
    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: Institute of Robotics and Industrial Informatics (IRI)
    Mode: Normal
    Deposit date: 19/02/2021
    Reading date: 27/04/2021
    Reading time: 11:00
    Reading place: ETSEIB- Defensa per videoconferència per COVID-19 https://meet.google.com/wpr-cukh-mbg
    Thesis director: THOMAS ARROYO, FEDERICO
    Committee:
         PRESIDENT: OTTAVIANO, ERIKA
         SECRETARI: ROS GIRALT, LLUIS
         VOCAL: SALTARÉN PAZMIÑO, ROQUE JACINTO
    Thesis abstract: Since the map from quaternions to rotation matrices is a 2-to-1 covering map, this map cannot be smoothly inverted. As a consequence, it is sometimes erroneously assumed that all inversions should necessarily contain singularities that arise in the form of quotients where the divisor can be arbitrarily small. This misconception was clarified when we found a new division-free conversion method. This result triggered the research work presented in this thesis. At first glance, the matrix to quaternion conversion does not seem to be a relevant problem. Actually, most researchers consider it as a well-solved problem whose revision is not likely to provide any new insight in any area of practical interest. Nevertheless, we show in this thesis how solving the nearest rotation matrix problem in Frobenius norm can be reduced to a matrix to quaternion conversion. Many problems, such as hand-eye calibration, camera pose estimation, location recognition, image stitching etc. require finding the nearest proper orthogonal matrix to a given matrix. Thus, the matrix to quaternion conversion becomes of paramount importance. While a rotation in 3D can be represented using a quaternion, a rotation in 4D can be represented using a double quaternion. As a consequence, the computation of the nearest rotation matrix in 4D, using our approach, essentially follow the same steps as in the 3D case. Although the 4D case might seem of theoretical interest only, we show in this thesis its practical relevance thanks to a little known mapping between 3D displacements and 4D rotations. In this thesis we focus our attention in obtaining closed-form solutions, in particular those that only require the four basic arithmetic operations because they can easily be implemented on microcomputers with limited computational resources. Moreover, closed-form methods are preferable for at least two reasons: they provide the most meaningful answer because they permit analyzing the influence of each variable on the result; and their computational cost, in terms of arithmetic operations, is fixed and assessable beforehand. We have actually derived closed-form methods specifically tailored for solving the hand-eye calibration and the pointcloud registration problems which outperform all previous approaches.

DOCTORAL DEGREE IN NUCLEAR AND IONISING RADIATION ENGINEERING

  • COELLO DE PORTUGAL - MARTINEZ VAZQUEZ, JAIME MARIA: Local Optics Corrections in the HL-LHC
    Author: COELLO DE PORTUGAL - MARTINEZ VAZQUEZ, JAIME MARIA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN NUCLEAR AND IONISING RADIATION ENGINEERING
    Department: Institute of Energy Technologies (INTE)
    Mode: Normal
    Deposit date: 17/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: TOMAS GARCÍA, ROGELIO | KOUBYCHINE MERKULOV, YOURI ALEXANDROVICH
    Committee:
         PRESIDENT: PEREZ RODRIGUEZ, FRANCISCO JOSE
         SECRETARI: CORTES ROSSELL, GUILLEM PERE
         VOCAL: DALENA, BARBARA
    Thesis abstract: In order to increase the performance of particle colliders, it is crucial to make the beam sizes at the collision points as small as possible. This causes an increase of the beam size in the region surrounding the collision points thus enhancing the effect of magnetic errors. These errors must therefore be kept under tight control to ensure the performance and safety of the accelerator.The present thesis studies effects of the expected magnetic errors in the regions around the collision points on the beam optics that determine the beam size in the future High-Luminosity upgrade of the Large Hadron Collider (HL-LHC), a 27 km particle accelerator situated on the French-Swiss border near Geneva, Switzerland. It has become clear in recent years that in correcting the magnetic errors in this region a crucial requirement is an accurate measurement of the beam optics at the collision point. This thesis demonstrates that the technique used traditionally in recent years, called ¿K-modulation¿, is not accurate enough to ensure the performance of the HL-LHC and therefore alternative methods of performing this measurement must be studied.To perform these studies a new automatic optics correction tool has been developed and is presented in this thesis. This new tool allows faster and more systematic calculation of corrections of the magnetic errors around the interaction regions and has been successfully tested during commissioning and experiments in the LHC.Two complementary techniques are proposed in order to improve the accuracy of the determination of the beam sizes at the collision points, namely determining the minimum beam size near the collision point using the ¿phase-advance¿ of the beam oscillations around the accelerator and locating the position of this minimum, the ¿beam waist¿, by displacing it and maximising the collision rate characterized by the collider luminosity. In the thesis these techniques are studied theoretically, and the first results of their experimental validation performed in the LHC are presented.This push for smaller beam sizes at the collision points not only increases the beam sizes in sections around this point but also, though to lesser degree, in the arcs of the accelerator. These regions also become susceptible to smaller magnetic errors. As some regions of the accelerator do not count with adequate corrector magnets alternative solutions are needed. Here we present the first experimental results of an optics correction performed by traversing sextupoles with off-central beam in the LHC as a solution proposal. Another consequence of the growth of the beam sizes in the regions around the collision points is the eventual necessity for larger beam pipes. This is the case for HL-LHC where the magnetic lenses around the collision points are going to be replaced by new ones with the beam pipe of larger diameter. In order to keep the same magnetic strength though a new superconducting technology is going to be used to build these magnets. A downside of this novelty is that it is susceptible to a type of magnetic instability called ¿flux-jumps¿. In the thesis the effect of the flux-jumps on the beam sizes is studied theoretically and concrete predictions using measurements of this effect on the prototypes of the new magnets of the HL-LHC are given. The study is also extrapolated to the Future hadron-hadron Circular Collider (FCC-hh), a proposed 100 km circular collider, in which superconducting magnets of this type are expected to be installed all around its circumference.Finally, the thesis presents a summary of software developments performed during the previously mentioned studies, including a user interface to facilitate the use of the automatic correction tool, a new harmonic analysis program that replaces legacy code and many refactors and rewrites that have significantly eased the development of the optics measurements and corrections programs.

DOCTORAL DEGREE IN PHOTONICS

  • SAEMISCH, LISA CHRISTIN: Large-scale imaging of optical antennas and single molecules
    Author: SAEMISCH, LISA CHRISTIN
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN PHOTONICS
    Department: Institute of Photonic Sciences (ICFO)
    Mode: Normal
    Deposit date: 10/03/2021
    Reading date: 15/04/2021
    Reading time: 15:00
    Reading place: ICFO - Avda. Carl Friedrich Gauss, 3 - videoconferència: http://s.ic.fo/D0Qyj
    Thesis director: VAN HULST, NIEK
    Committee:
         PRESIDENT: NOVOTNY, LUKAS
         SECRETARI: GARCÍA PARAJO, MARÍA
         VOCAL: WERTZ, ESHTER ALEXANDRA
    Thesis abstract: The interaction of light and matter is of crucial importance in fundamental science as well as in high-end technology.Ultimately, this concerns the interaction between a photon and a single quantum system, e.g. the absorption or emission of aphoton by a single molecule. At room temperature this interaction is very inefficient as the absorption cross-section of a molecule is small compared to the wavelength of light, which inhibits many photons from interacting and hence limits theabsorption, emission and scattering of a photon. An equivalent problem, and its solution, is found in our daily lives: small electric circuits (as found e.g. in our smartphones), which radiate very poorly by themselves, are linked to (radio) antennas toradiate and transfer information efficiently. Analogously, antennas working in the visible, so-called nanoantennas, are an effective tool to link matter and light. The strength of the coupling of a single molecule with a nanoantenna depends on many factors: the overlap of the antenna resonance and the molecular absorption/emission spectrum, the molecule¿s dipole orientation, the distance between molecule and nanoantenna, etc. Hence, strong interaction needs rather special conditions, which are hard to engineer. Moreover, to get a full interaction picture, a lot of single molecule encounters with different nanoantennas are needed - on one hand to make a statistically relevant statement including the many different factors and, on the other hand, to be able to observe the rare stronger interactions, that would have stayed hidden in experiments of only afew encounters. The central idea of this thesis is to statistically map and control the interactions of a very large number of single moleculeswith different tailored nanoantennas, to cover the landscape of interaction factors and thus extend the current knowledge of the mutual interaction. For this purpose, a home-built wide-field microscope is combined with a large array of lithographically fabricated nanoantennas, which are all probed by freely diffusing molecules. Thus in time millions of encounters are recorded in parallel.Chapter 2 introduces the necessary knowledge and methodology to understand the research work presented in chapters 3 to 5. Chapter 3 shows super-resolved nanoscale interaction maps of molecules and nanoantennas, linking the strength ofinteraction to the emission polarization and intensity of every encounter. Chapter 4 extends this approach by simultaneously recording the emission fluorescence and spectrum of every single molecule event, revealing strong spectral manipulation.Here, a suppression as well as an extreme enhancement of the vibrational sideband of the used molecule is observed.Additionally, the statistical mapping allows the freely diffusing molecules to encounter rare hotspots of extreme field intensities, enabling the observation of surface-enhanced Raman scattering.Finally, chapter 5 takes the first step in the direction of characterizing the interaction of molecule and nanoantenna with high sensitivity via phase measurements. Here, an interferometric wide-field microscope enables the measurement of the absolute phase of nanoparticles and demonstrates the distinction of different plasmonic and dielectric particles via their phase behavior. Furthermore, we implement a novel two-color excitation method, capable of rapidly identifying two types of nanoparticles in a single-shot image.

DOCTORAL DEGREE IN POLYMERS AND BIOPOLYMERS

  • KERIDOU, INA: Study on Crystallinity, Properties and Degradability of Poly-4-hidroxybutyrate and Related Polyesters
    Author: KERIDOU, INA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN POLYMERS AND BIOPOLYMERS
    Department: Department of Chemical Engineering (EQ)
    Mode: Temporary seizure
    Deposit date: 16/02/2021
    Reading date: 14/04/2021
    Reading time: 11:30
    Reading place: Aula A1.03 Edifici A EEBE - CAMPUS DIAGONAL BESOS - Av. d'Eduard Maristany, 16, 08930 Barcelona - videoconferència: https://meet.google.com/icx-eqyd-eab
    Thesis director: PUIGGALI BELLALTA, JORGE | FRANCO GARCIA, MARIA LOURDES
    Committee:
         PRESIDENT: MEAURIO ARRATE, EMILIANO
         SECRETARI: FERNANDEZ FRANCOS, XAVIER
         VOCAL: REINA LOZANO, JOSE ANTONIO
    Thesis abstract: In the last decades, polymeric biomaterials, due to their advanced physical and mechanical properties, have been used in a vast variety of surgical and pharmaceutical applications. In this thesis, a study on crystallinity, properties, and degradability ofpoly-4-hydroxybutyrate (P4HB), commercially marketed as MonoMax® by B. Braun Surgical S.A.U. as an absorbable monofilament suture, and related polyesters is presented. ·Part of this work has been executed under the collaborative research project established between PSEP (Polímeros Sintéticos. Estructura y Propieda s) research group of Universitat Politécnica de Catalunya and B. Braun Surgical S.A.U. (Center of Excellence far Closur :Technologies) with the principal purpose of evolving ahd investigating polymeric systems with specific biomedical ápplications.This study covers different tapies related to P4HB such as (a) the physical, chemical, thermal and mechanical characterization;(b) the study of the crystallization kinetics; (c) the study of the degradation behavior of P4HB; and (d) the production of nanofibers by the electrospinning technique. Moreover, the work includes a study on blends of two different polyesters: PGA/PCL blends also produced employing the electrospinning technique and biphasic PLA/PA blends.Crystallization was studied under both isothermal and non-isothermal conditions using optical microscopy and differential scanning calorimetry. Furthermore, supplementary experiments performed in a synchrotron radiation facility provided us with further information about the lamellae morphology, crystal structure, and molecular orientation.Hydrolytic and enzymatic degradation of different matrices of P4HB was carried out in different buffered media. The hydrolytic degradation has been studied considerírig media of different pH values and temperatures. Enzymatic degradation has also been evatu ated at physiotogical conditions using two different lipases. The hydrolytic degradation mechanism differs from the enzymatic, where bulk degradation and a random éháin scission are characteristic of samples exposed to hydrolytic media, whereas surface erosion and successive removal of monomer units are charac!eristlc of samples exposed to enzymatic media. Far annealed fibers, small-angle X-ray diffraction studies revealed a supramolecular structure with two different types of !amellar stacks. The spherulitic morphology of the enzymatically degraded films was highlighted by the elimination of the amorphous regions.Nanofibers of PGA/PCL and P4HB were preparad using the electrospinning technique. The PGA/PCL nanofibers were also loaded with pharmacological drugs and Lised as a reinforcing agent of biodegradable polymer matrices. On the other hand, the biologicat performance of P4HB nanofibers was achieved with the incorporation of fibroblast growth factors. Far this purpose, wound healing assay for two different cell lines (e.g., epithelial and fibroblast) were studied.Finally, a study on the blends of PLA and Polyamide 6,1O was carried out to investigate the confinement effect of neighboring polymer domains on the phase separation and the structure and the influence of the disperse phase of polyamide in promotingPLA crystallization.

DOCTORAL DEGREE IN SUSTAINABILITY

  • RUIZ ALMEIDA, ADRIANA: Sustainability of the Agri-food System¿s Characterization with Food Sovereignty Framework and the Evaluation Approach of the Major Threats
    Author: RUIZ ALMEIDA, ADRIANA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN SUSTAINABILITY
    Department: University Research Institute for Sustainability Science and Technology (IS.UPC)
    Mode: Normal
    Deposit date: 03/12/2020
    Reading date: 29/04/2021
    Reading time: 15:00
    Reading place: Aula C2-001 ETSECCPB - UPC Campus Nord - VIDEOCONFERÈNCIA enllaç: https://meet.google.com/mvh-gcwb-mpp
    Thesis director: RIVERA FERRE, MARTA GUADALUPE | ROSAS CASALS, MARTI
    Committee:
         PRESIDENT: CUÉLLAR PADILLA, MAMEM
         SECRETARI: GIL ROIG, JOSE MARIA
         VOCAL NO PRESENCIAL: LOPEZ I GELAT, FELIU
    Thesis abstract: Nowadays, around 690 million undernourished people worldwide, even though the world already produces enough food to feed more than the whole current population. This situation is far from diminishing due to the current COVID-19 worldwide health contingency and other environmental threats, e.g., climate change. This work establishes key parameters to build a sustainable agri-food system that allows characterizing the degree of sustainability of the global agri-food system following the food sovereignty framework. It is divided into three main sections, two of them has a published article. The first one proposes a quantitative methodology that analyzes food systems' functioning at the international level. That section presents a database with 97 indicators distributed into six categories: 1) access to resources; 2) productive models; 3) commercialization; 4) food consumption and the right to food; 5) agrarian policies and civil society organization, and 6) gender. Then, the second section advances the concept of food sovereignty as a conceptual framework to analyze agri-food systems' sustainability following the steps proposed by Jabareen (2009) to build conceptual frameworks. The third section presents a quantitative multivariate assessment of 43 indicators of food sovereignty and 39 indicators of socio-demographic and social well-being and environmental sustainability in 150 countries. Finally, I conclude this dissertation with final remarks and further work on the forthcoming final paper submitted in the first quarter of 2021.
  • SILVA LAYA, SILVIA JOSEFINA: Dinámicas socioecológicas de la producción de durazno bajo el sistema de agricultura familiar periurbana en El Jarillo, Venezuela
    Author: SILVA LAYA, SILVIA JOSEFINA
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: DOCTORAL DEGREE IN SUSTAINABILITY
    Department: (DECA)
    Mode: Article-based thesis
    Deposit date: 27/11/2020
    Reading date: 21/04/2021
    Reading time: 17:00
    Reading place: ETSECCPB - CAMPUS NORD - C/ Jordi Girona, 1, 08034 Barcelona - videoconferència: https://meet.google.com/qrf-iida-kvy
    Thesis director: ALVAREZ DEL CASTILLO, JAVIER | PÉREZ MARTÍNEZ, SIMÓN
    Committee:
         PRESIDENT: GONZALEZ DE MOLINA, MANUEL
         SECRETARI: HAURIE IBARRA, LAIA
         VOCAL NO PRESENCIAL: PENGUE, WALTER
    Thesis abstract: The Jarillo, Venezuelan Mirandina parish, has had an intense agricultural development since the end of the 19th century, the peach occupies one of its main crops since the middle of the last century. They are currently the second production community of this fruit at the national level. Producing families have indiscriminately employed the use of agrochemicals to increase and maintain their productivity, with negative effects on the environment and on human health. There is an appreciation that the economic success produced by producers is unquestionable. A series of problems (ecological, economic and socio-cultural)related to the agricultural development model that is explained from a multidimensional perspective and studied from the perspective of complex systems are combined. An unidisciplinary look used in other works in El Jarillo does not help tounderstand the complexity of the relationships that are woven around the use of agrochemicals to increase agricultural productivity as an essential attribute of the jarrilla family farming system. The objective of this work was to integrate the ecological and social dimensions in a study of the socio-ecological dynamics that are defined between the different elements of the familyfarming system and their levels of analysis, with the purpose of understanding the adaptation and transformation processes that it undergoes The system in relation to the use of agrochemicals. A study of complex systems was designed in which a theoretical model was constructed in a participatory manner where the central process is used in agrochemicals to increase agriculturalproductivity in the family farming system of El Jarillo, Venezuela. Three levels of analysis were defined: local, at farm level (first),regional (second) and national (third). The time scale that was considered for the agro-productive subsystem was influenced by two events that marked the history of El Jarillo as an agricultural producing agricultural zone: a) the incorporation of peaches as the main production item (in the 30s, last century) and b) the adoption of green revolution techniques as the main form ofmanagement in agricultural production (from the 60s, also from the last century). To conceive the model, we first structured an epistemological framework with theoretical bases from a documentary review and then, with a systematic review to define the concept of socio-ecological systems of peri-urban family farming. Then we proposed a methodology of diagnosis, characterization and typification of these systems; as well as energy efficiency compared to monetary efficiency. With the information we model the system and validate it in the community with the families. The system presented a complex structureand dynamic relationships involved in the phenomenon of production. A scenario of technical / Figura 1. Estructura metodológica propuesta para comprender las dinámicas socioecológicas de la producción de durazno bajo el sistema de agricultura familiar periurbana en el Jarillo, Venezuela productive difficulties in ecological management was identified, clearly determined by the use of agrochemicals to increase productivity, control pests and diseases and fertilize the soil (local level). At the national level, thelack of support was identified by the State to promote a transition towards systems that are less harmful to human and environmental health.

DOCTORAL DEGREE IN THERMAL ENGINEERING

  • PAPAKOKKINOS, GIORGOS: Computational modeling ofadsorption packed bed reactorsand solar-driven adsorptioncooling systems
    Author: PAPAKOKKINOS, GIORGOS
    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: 25/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: CASTRO GONZALEZ, JESUS | OLIVA LLENA, ASENSIO
    Committee:
         PRESIDENT: FERNÁNDEZ SEARA, JOSÉ
         SECRETARI: PEREZ SEGARRA, CARLOS DAVID
         VOCAL NO PRESENCIAL: PRIETO GONZÁLEZ, MARIA MANUELA
    Thesis abstract: Environmental concerns regarding climate change and ozone depletion urge for a paradigm shift in the cooling production. The cooling demand exhibits an alarmingly increasing trend, thus its satisfaction in a sustainable manner is imperative. Adsorption cooling systems (ACSs) are a potential candidate for a sustainable future of cooling production, since they can utilize solar energy or waste heat, as well as they can employ substances with zero ozone depletion and global warming potential. The objective of this thesis is to contribute to the investigation and improvement of ACSs, through the development of two computational models - which approach ACSs from different perspectives - and their respective utilization for the conduction of related numerical studies. The first research direction focuses on the design of the adsorption reactor, the most vital component of ACSs. Its geometrical configuration is determinant for the system performance. The reactor design is a crucial task since it creates a dichotomy between the two performance indicators - the Specific Cooling Power (SCP) and the Coefficient of Performance (COP). Individual optimizations based on the SCP and the COP would result in completely opposite geometrical configurations. A computational model for the simulation of adsorption packed bed reactors was developed, capable of simulating any potential reactor geometry. A multi-timestep approach is adopted, resulting in a drastic reduction of the computational cost of the simulations. Verification and validation assessments were performed in order to evaluate the reliability of the model. Two major studies were conducted within this research direction. The first aspires to provide a comparison between five reactor geometries, motivated by the lack of comparability across different studies in the literature. Thirteen cases of each geometry are simulated, by varying the fin thickness, fin length and solid volume fraction. The second study pertains to a thorough investigation of a geometry that remained underexplored hitherto - the hexagonal honeycomb adsorption reactor. A parametric study is conducted with respect to the three dimensions that define the geometry, as well as for various operating conditions.The second research direction is dedicated to the investigation of adsorption cooling systems, and in particular, to their integration within a wider thermal system, a solar-cooled building. Such integration is not straight-forward due to thermal inertia effects and the inherent cyclic operation of ACSs, as well as due to the dependence on an intermittent source and an auxiliary unit, with a clear objective to prioritize solar energy. A numerical model was developed using 1-d models for the adsorption reactors and 0-d models for the evaporator and condenser. The model is validated against experimental results found in the literature. The model is coupled to the generic optimization tool GenOpt, thus allowing the conduction of optimization studies. The ACS model is then coupled to solar collectors and thermal storage models, as well as to a building model. The latter was previously developed in the CTTC laboratory. This coupling results in a comprehensive simulation tool for adsorption-based solar-cooled buildings. A case study for a solar-cooled office is considered, with the objective to investigate the potential of satisfying its cooling demand using solar energy. A control strategy is proposed based on variable cycle duration, using optimized values for the instantaneous operating conditions. The variable cycle duration approach allows to satisfy the cooling demand using significantly less solar collectors or less auxiliary energy input. The potential carbon dioxide emissions avoidance is calculated between 28.1-90.7% with respect to four scenarios of electricity-driven systems of different performance and carbon emission intensity.

ERASMUS MUNDUS DOCTORAL DEGREE IN SIMULATION IN ENGINEERING AND ENTREPRENEURSHIP DEVELOPMENT

  • EL-GHAMRAWY, KARIM MOHAMED SHAKER IBRAHIM: Proper Generalized Decomposition solutions for composite laminates parameterized with fibre orientations for fast computations
    Author: EL-GHAMRAWY, KARIM MOHAMED SHAKER IBRAHIM
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: ERASMUS MUNDUS DOCTORAL DEGREE IN SIMULATION IN ENGINEERING AND ENTREPRENEURSHIP DEVELOPMENT
    Department: (DECA)
    Mode: Change of supervisor
    Deposit date: 10/03/2021
    Reading date: 23/04/2021
    Reading time: 15:00
    Reading place: VIDEOCONFERENCIA Estat alarma Covid-19 - ETSECCPB, aula C2-001 enllaç: meet.google.com/kpb-yurw-yim
    Thesis director: AURICCHIO, FERDINANDO | DIEZ MEJIA, PEDRO | ZLOTNIK MARTINEZ, SERGIO
    Committee:
         PRESIDENT: SACCO, ELIO
         SECRETARI: CUETO PRENDES, ELIAS
         VOCAL NO PRESENCIAL: MARFIA, SONIA
    Thesis abstract: Composite materials are gaining popularity as an alternative to classical materials in many different applications. Moreover, their design is even more flexible due to the potential of additive manufacturing. Thus, one can produce a tailored composite laminate with the optimal values of some design parameters providing the desired mechanical performance. In this context, having a parametric numerical model for the mechanical response of the composite laminate is essential to compute the optimal parameters. Generally, solving a mechanical model using mesh-based techniques in 3D is computationally expensive and at some point it could become infeasible when the problem is multidimensional. Furthermore, if the problem under consideration is an application requiring multiple queries such as optimization, inverse problems,or uncertainty quantification, the direct problem is solved numerous times increasing drastically the computational burden. In the present thesis, the design parameters under consideration are the angles describing the orientation of the reinforcement fibers in different layers or patches of the composite laminates. We present the Tsai-Wu failure criterion as the objective function of the optimization problem. The use of a Model Order Reduction (MOR) technique is advocated to alleviate the mentioned computational burden. Namely, we resort to the Proper Generalized Decomposition (PGD) to obtain the generalized solution of the structure mechanical response. Particularly, we obtain a 3D computational vademecum which provides laminate failure index and safety factor that depend explicitly on the fiber orientation. The PGD vademecum provides also sensitivities for a gradient-based optimization algorithm. The potentiality and efficiency of the presented approach is demonstrated through some numerical tests. Finally, a coupling between the proposed methodology and clustering techniques is presented to enhance the overall performance of the model.

NAUTICAL ENGINEERING, MARINE AND NAVAL RADIOELECTRONICS

  • JURADO GRANADOS, JOEL: Desarrollo e implementación de una formulación utilizando la teoría de mezclas serie/paralelo para la modelización de estructuras navales de materiales compuestos sometidas bajo cargas cíclicas
    Author: JURADO GRANADOS, JOEL
    Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
    Programme: NAUTICAL ENGINEERING, MARINE AND NAVAL RADIOELECTRONICS
    Department: Department of Nautical Sciences and Engineering (CEN)
    Mode: Normal
    Deposit date: 24/03/2021
    Reading date: pending
    Reading time: pending
    Reading place: pending
    Thesis director: MARTINEZ GARCIA, JAVIER | DI CAPUA, DANIEL
    Committee:
         PRESIDENT: PAREDES LÓPEZ, JAIRO ANDRÉS
         SECRETARI: OTERO GRUER, FERMÍN ENRIQUE
         VOCAL: KADIYALA, AJAY KUMAR
    Thesis abstract: The main goal of this thesis is the simulation of the performance of composite naval structures subjected to cyclic loads. The predicted behavior expected is the fatigue life of the composite structure, as well as the fatigue failure mechanisms. This achievement is conducted by coupling the serial/parallel mixing theory and a fatigue damage model. Consequently, the work has the following stages.In first place, a study is conducted in order to identify the failure mechanisms of composites in fatigue and how the different factors affect it, in order to propose a fatigue constitutive model for fibre and matrix. The review uses a constituent materials point of view, thus fatigue performance of fibres and resins are analyzed, as well as their role in each failure mechanisms. In addition, different variables that may affect fatigue behavior are described.Secondly, a numerical procedure for characterizing fibres and matrix is proposed, in order to predict the failure mechanisms in composites subjected to static loads. The procedure defines which experimental tests should be conducted and what material parameters are obtained from them. As a consequence, the material parameters of the constituent materials are defined, obtaining the failure of the composite by the failure of the constituent materials, without pre-defining the expected failure.The next stage is coupling the serial/parallel mixing theory and the fatigue model. The fatigue model modifies the constitutive equation of the components, while the rule of mixtures acts as a constitutive law manager. The fatigue models of fibre and matrix are characterized, assuming that the fatigue behavior of unidirectional laminates is driven by one of the constituents, in function of the loading direction. This methodology is validated for two different composite systems: a carbon epoxy cross-ply laminate and glass/polyester balanced angle-ply laminates.Finally, this numerical methodology is applied to two naval structures: a small section of a container ship and a flexible composite blade of a marine propeller. The two analyses obtain the failure mechanisms of both structures, as well as the ply or plies failing, and the corresponding constituent material causing the failure. One of the fatigue analyses is used in order to propose a simplified method capable of predicting the fatigue initiation in the structure, by only applying a quasi-static analysis. This method is based on comparing the maximum equivalent stress in the components with their SN fatigue curve.

Last update: 14/04/2021 05:14:06.