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

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

Author: FLORES GARCIA, JUAN CARLOS
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN COMPUTATIONAL AND APPLIED PHYSICS
Department: Department of Physics (FIS)
Mode: Normal
Deposit date: 27/04/2022
Reading date: pending
Reading time: pending
Reading place: pending
Thesis director: CALDERON MORENO, JOSE MARIA | CRESPO ARTIAGA, DANIEL
Committee:
     PRESIDENT: BATLLE GELABERT, XAVIER
     SECRETARI: PRADELL CARA, TRINITAT
     VOCAL: MOLERA I MARIMÓN, JUDIT
Thesis abstract: In this thesis, the results ofdifferentcore-shell structures are presented after having been synthesized bythe modified Stober method, results of UV-Vis, SEM, TEM, XRD, among others, are shown, which determined the composition, morphology, and crystalline structure of particles of subm icron and even nanom etric size. Each chapter shows the results of the production and characterization of core-shell structures. Different core-shell structures with a varietyof morphologies were produced using a simple, robust and rapid chem ical m ethod, without the addition of coupling agents or surface modifications of the silica.In the first chapter, SiO2@ core-shell nanospheres ("50±10nm) were prepared, whose silver nanoparticles have sizes of - 4±2 nm in diameter. The preparation route is a modification ofthe Stober method, and im.olves the preparation of homogeneous silica spheres at room temperature, combined with the deposition of silver nanoparticles + in solution, by using water/ethanol mixtures, tetraethyl-orthos ilicate as Si source and silver nitrate as a source in a wet chem ical method in one pot, without the addition of coupling agents or surface modification, leading to the formation of homogeneous core­ shell nanospheres. The preparation and characterization ofSiO2@ core-shell nanospheres and also ofnal<ednanospheres, in the absence of silver, are presented, and the reaction mechanism s for the form ation of core-s hell structures are proposed.The second chapter presents three differ-ent silver nanoshells morphologies, produced on silica spheres using the módified Stober method, previous ly proposed, adding a second supply of silver nanoparticles, which leads to the form ation of silica core-silver nanoshells with silica cores from 50 to 600 nm in diameter and silver shells morphologies ranging from continuous, uniform and smooth layer about 10 nm thick, to rough surfaces of 3-5 nm nanoparticles to sharp spikes-like silver protrusions extending outward from the surface of the silica. We propose reaction mechanisms for the form ation of the different silica-silver core-shell nanostructures.In the third chapter we describe the production of a smooth and uniform silver outer nanoshell with a thickness of - 15 nm on submicrospheric silica, using a rapid and simple one pot chemical route. The reaction mechanisms proposed for the formation of silver nanoshell is the reactivity of silver nanoparticles with surface silanols at high pH, without added coupling¿. agents or surface m odification of silica, leading to the form ation of the continuous and hom ogeneous silver nanoshell on the silica spheres.The fourth chapter reviews the deposition of silver nanoparticles on the surface of silica us ing our simple, robust and fast chemical method without surface modification of silica or added coupling agents. The process was carried out at room temperature, in a single reaction process, using water/methanol mixtures, tetraethyl-orthosilicate as a Si source and silver nanoparticles (NPs). Using EDS, XRD, HRTEM and High Angle Annular Dark Field (HAADF) STEM characterization techniques, we have found the coexistence of silver NPs and silver oxide NPs anchored to the surface of subm icron silica spheres, with NPs predominating sizes around 2-3 nm approximately, and 20 NPs sizes over 1O nm.Each ofthese presented articles describe the preparation and characterization ofthe core-shell SiO2@ structures and propase the reaction mechanisms. Finally, we presented the analysis and conclusion ofthis work.

Author: MACIÀ SORROSAL, SANDRA
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN COMPUTER ARCHITECTURE
Department: (DAC)
Mode: Temporary seizure
Deposit date: 08/04/2022
Reading date: 26/05/2022
Reading time: 11:00
Reading place: FIB - ( https://meet.google.com/tis-ajpk-ogr ) Sala C6-E101 de la FIB
Thesis director: AYGUADÉ PARRA, EDUARD | BELTRAN QUEROL, VICENÇ
Committee:
     PRESIDENT: QUINTANA ORTI, ENRIQUE SALVADOR
     SECRETARI: MARTORELL BOFILL, XAVIER
     VOCAL NO PRESENCIAL: BULL, JONATHAN MARK
Thesis abstract: High-Performance Computing (HPC) evolves vertiginously.Supercomputers are increasingly powerful and complex machines that require deep expertise to be well-exploited.Currently, scientists develop HPC codes using General Purpose Languages (GPLs) and parallel programming models.However, such abstractions are falling short; developing advanced numerical methods and cutting-edge parallelisation strategies requires time, effort and deep computer science expertise, which is unreasonable to expect from other domain scientists.Scientific productivity has become a research challenge.In order to overcome this challenge, computational science demands instruments for practical parallel computations, abstracting scientists from HPC complexities while ensuring the efficient and full exploitation of HPC systems.In this context, Domain-Specific Languages (DSLs) are promising frameworks integrating specific knowledge and capable of automating parts of the code development process.DSLs can become the so-needed productive working environment by decoupling the problem description from the algorithmic implementation.Our task is to push the boundaries of DSLs capabilities and explore their strengths and limitations in HPC environments.We focus on the Computational Fluid Dynamics (CFD) domain to accomplish it.CFD is a field of vast scientific interest and essential for many branches of engineering and industry. Besides its broad applicability, results are obtained from numerical approximations, which can be highly accurate in a reasonable amount of time and investments if CFD codes exploit HPC resources.The object of this thesis is the design and development of Saiph, a DSL for CFD in HPC, exploring the limits of usability, numerical abstraction and automated high-per\-for\-mance.This research provides a high-productivity tool allowing for the direct transcription of CFD problems to generate optimised and mathematically checked code.Saiph provides suitable high-order numerical methods delivering competitive performance and highly accurate and stable results on the numerical side.Moreover, Saiph automatically combines numerical methods, freeing the users from numerical complexities.Finally, the automated use of parallelisation strategies provides high efficient and scalable parallel codes, exploiting current HPC machines at different resource levels.Vectorisation and data-blocking techniques automatically combine with shared and distributed memory parallelisms through fork-join or task-based models and domain decomposition techniques, respectively.We demonstrate the viability and benefits of the DSL, proving it to be a productive and competitive tool for the scientific community.Hence, the DSL philosophy arises as a promising research methodology facing the Exascale era.

Author: ALFARO ARAGÓN, CARLOS ARTURO
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN ELECTRONIC ENGINEERING
Department: Department of Electronic Engineering (EEL)
Mode: Article-based thesis
Deposit date: 02/05/2022
Reading date: pending
Reading time: pending
Reading place: pending
Thesis director: GARCIA DE VICUÑA MUÑOZ DE LA NAVA, JOSE LUIS | GUZMAN SOLA, RAMON
Committee:
     PRESIDENT: FIGUERES AMORÓS, EMILIO
     SECRETARI: CASTILLA FERNANDEZ, MIGUEL
     VOCAL: GARCERÁ SANFELIU, GABRIEL
Thesis abstract: This doctoral thesis focuses on the modeling and control of electrical microgrids and triphasic converters. The starting points of this research work are based on previous work on modeling electrical microgrids working in isolated mode, and on the theoretical basis of control based on the slope method, widely studied in electrical microgrids. In addition, this work is basedon previous work on predictive control applied to three-phase converters, and on the theoretical bases of this type of control widely used in Power Electronics. The main contribution of this doctoral thesis is the deduction of a large-signal mathematicalmodel that describes the dynamics of the active and reactive powers that flow through converters connected in the microgrid.This proposal will make it possible to obtain new control techniques for three-phase converters connected in microgrids, suchas model-based predictive control, for example. It should be noted that the use of this model can be used as a tool to deducethe global stability of the microgrid. The systems treated in this thesis are a three-phase rectifier with a unity power factor anda three-phase microgrid composed of five three-phase inverters.