Doctoral School

Reading date: 10/05/2024

• BENINCA, LETIANE: Multi-objective optimization for social multifamily housing: Minimizing heating and cooling demand
  
  Author: BENINCA, LETIANE
  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: Change of supervisor
  Deposit date: 11/04/2024
  Reading date: 10/05/2024
  Reading time: 13:00
  Reading place: Presencial Sala de Graus ETSAB. Planta Baixa + videoconferència:meet.google.com/cpp-awed-vth
  Thesis director: CRESPO SÁNCHEZ, EVA | PASSUELLO, ANA CAROLINA
  Committee:
       PRESIDENT: DE MOURA FERREIRA DANILEVICZ, ANGELA
       SECRETARI: KAMPOUROPOULOS, KONSTANTINOS
       VOCAL: CÓSTOLA, DANIEL
  Thesis abstract: The field of architecture and engineering is currently experiencing significant changes due to advances in technology and the growing role of Artificial Intelligence. This shift is largely driven by the growing urgency of promoting more efficient buildings, especially considering its substantial impact on global greenhouse gas emissions and energy usage. Consequently, it is becoming important to focus on practical design choices and utilize effective strategies to enhance energy efficiency and overall building performance. This thesis presents a comprehensive approach to optimize the shape, solar orientation, and envelope configuration of social residential buildings in a humid subtropical climate (Koppen classification: Cfa) in the southern region of Brazil. The main objective is to simultaneously minimize both heating and cooling demands, and present optimal performance design and parameter ranges to improve efficiency energy in multifamily buildings. To achieve this, the study utilizes multi-objective optimization techniques with the support of a non-dominated sorting genetic algorithm (NSGA-II). The simulations are conducted using the EnergyPlus while the optimization process is implemented through Python programming. This extensive computational effort involves a total of 480,000 simulations. The results of the optimization process demonstrate that by carefully selecting the optimal solar orientation, significant reductions in energy demand can be achieved. For instance, optimizing the solar orientation alone can lead to energy demand reductions of up to 5% for linear buildings and 11% for H buildings, when linked to the surroundings. Furthermore, when the envelope is properly addressed the energy demand between shapes achieves almost the same value. Moreover, the optimization of the building envelope configuration further enhances energy efficiency, resulting in remarkable reductions in total energy demand. In particular, linear buildings can achieve up to 60% reduction in energy demand, while H buildings reach up to 63% reduction. These findings highlight the potential benefits of considering solar orientation, surrounding shadows, and envelope design simultaneously during the early design stages of a project. The proposed three-phase optimization framework evaluates different parameter alternatives and presents a pratical guidelines to make informed decisions about the most energy-efficient configurations.
  

• GORDON POZUELO, SANDRA: Mechanical integrity of coated PcBN systems: Mechanics and mechanisms involved under service-like conditions
  
  Author: GORDON POZUELO, 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 MATERIALS SCIENCE AND ENGINEERING
  Department: (CEM)
  Mode: Article-based thesis
  Deposit date: 19/02/2024
  Reading date: 10/05/2024
  Reading time: 11:00
  Reading place: EEBE (Escola d'Enginyeria Barcelona Est), Aula A2.14, planta 2, Campus Diagonal-Besòs
  Thesis director: LLANES PITARCH, LUIS MIGUEL | ROA ROVIRA, JOAN JOSEP
  Committee:
       PRESIDENT: MARI, DANIELE
       SECRETARI: FARGAS RIBAS, GEMMA
       VOCAL: BOTERO VEGA, CARLOS ALBERTO
  Thesis abstract: Polycrystalline cubic boron nitride (PcBN) is a composite competitive cutting tool material that excels performance when machining difficult-to-cut materials (e.g. hardened steels, superalloys, etc) due to its exceptional mechanical properties. In practice, PcBNs are coated with a ceramic film to prevent and prolong the onset of tribo-oxidation and abrasive wear. Although there is not a unique consolidated opinion regarding the benefits of coatings in PcBN, most of the bibliography agrees on their use when involving hard turning operations. Most of the research address the tool performance and wear mechanisms, whereas information involving materials science aspects of PcBN and coated PcBN tools, on the basis of understanding microstructure ¿ mechanical properties correlations, is quite limited. In this regard, this thesis focusses on studying hardness, fracture toughness and wear resistance as they are key mechanical properties controlling the mechanical integrity and reliability of the tool, which are related with the contact response, fracture resistance (e.g. premature chipping) and effective tool life, respectively. Four distinct substrates of the coated PcBN grades are studied and first characterized, including the development of characterization and testing protocols. In doing so, focus ion beam tomography and three-dimension (3D) image reconstruction was implemented to study the bulk microstructural characteristics of a PcBN grade with high cBN content and metallic binder. It was found to be a powerful and useful method to gain in-depth knowledge and understanding the microstructural characteristics of PcBN composite materials, additionally to those gathered by conventionally 2D method. The study then focuses on the assessment of the micromechanical properties of PcBN composite materials, as they are known to be key for optimizing their performance through microstructural design. High-speed nanoindentation is successfully implemented to characterize and correlate microstructure with local mechanical properties of such hard and stiff composite materials; where two different methodologies, 1D and 2D Gaussian, are used for statistically deconvoluting the data. It is found that the harder PcBN grade is clearly related with the high cBN content. A scaled-up method was employed to evaluate the contact response of uncoated PcBN grades. The higher cBN content and metallic binder grade, exhibits higher resistance to crack nucleation and a more gradual transition through different damage scenarios due to the concomitant increase of hardness and fracture toughness of this grade. Regarding fracture toughening mechanisms, crack path changes from propagation across the ceramic binder to transgranular fracture through cBN particles, as the cBN content increases. Very interesting, fracture toughness is enhanced by crack interaction with intrinsic sub-grained or twin boundaries within the individual cBN particles as well as by crack deviation through nano cBN particles dispersed in the binder. Afterwards, research was aimed to characterize coated PcBN (with different chemical nature and bias voltage), mainly in terms of coating adhesion strength and mechanical integrity of bulk coated systems as a function of the PcBN substrate microstructural assemblage. Mechanical response of the coated system, assessed by using Rockwell C indentation technique and scratch testing, is strongly dependent on the underneath substrate microstructural assemblage; and therefore, its different intrinsic hardness-toughness correlation. Finally, TiAlN-coated PcBN inserts were used to mill a hardened cold work tool steel. It was proposed as an exploratory study of milling performance of coated PcBN systems to assess the onset of coating failure without involving the emergence of other wear phenomena (e.g. thermally-driven ones).
  

• MAJORAL RAMONEDA, MARC: A Flexible System-on-Chip FPGA Architecture for Prototyping Experimental GNSS Receivers
  
  Author: MAJORAL RAMONEDA, MARC
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS
  Department: Department of Signal Theory and Communications (TSC)
  Mode: Normal
  Deposit date: 03/04/2024
  Reading date: 10/05/2024
  Reading time: 11:00
  Reading place: Edifici C4-Aula 021B (Escola d'Enginyeria de Telecomunicació de Castelldefels)
  Thesis director: FERNANDEZ PRADES, CARLOS | ARRIBAS LÁZARO, JAVIER
  Committee:
       PRESIDENT: CAPARRA, GIANLUCA
       SECRETARI: BARTZOUDIS, NIKOLAOS
       VOCAL: FONT BACH, JOSEP ORIOL
  Thesis abstract: The rapid evolution in satellite navigation technology (GNSS) requires advanced prototyping tools for exploring new signals and developing innovative systems. Prototyping is essential in the design and development process, as it allows researchers to test and refine their ideas before implementing them on a large scale.Prototyping using commercial GNSS receivers poses several challenges. Currently, these receivers are primarily based on application-specific integrated circuits (ASICs), which are characterized by low power consumption, compact dimensions, and low cost, but offer limited flexibility. Although some commercial devices incorporate software-defined radio (SDR) techniques, they often contain proprietary code that restricts reconfiguration through an application programming interface (API) established by the manufacturer.GNSS receivers based on free and open-source software have become very valuable resources in the field of research and development, especially in satellite navigation. These receivers are highly valued for their adaptability and flexibility, allowing researchers to tailor the software to specific experimental needs or develop new signal processing algorithms. However, software-defined receivers tend to be less energy-efficient compared to hardware-based receivers, as they operate on general-purpose processors, which are not optimized for low power consumption.This thesis focuses on the design and development of a low-cost architecture for prototyping experimental GNSS receivers, based on System-on-Chip Field Programmable Gate Arrays (SoC FPGAs). This architecture overcomes the limitations of commercial GNSS receivers in terms of adaptability, flexibility, and reprogramming capacity, and offers improved energy efficiency compared to software-based receivers that rely on general-purpose processors. The strategy consists of combining the versatility of software-defined radio with the intensive parallelism and optimized energy consumption of programmable logic devices, providing the best of both worlds. This fusion allows the development of compact, portable GNSS receivers, thus facilitating the prototyping of embedded devices suitable for field testing. In addition, the GNSS processing core is based on a free and open-source software implementation, which provides detailed access to the signal processing chain and allows unrestricted exploration and modification of the algorithms used.This thesis also presents a design methodology for the development of new prototypes and new GNSS signal processing algorithms based on the proposed SoC FPGA architecture. This methodology places special emphasis on code reuse, a key aspect for reducing development costs and time.The practical applications of this architecture have been demonstrated through three prototypes: a GNSS receiver for low Earth orbit (LEO), a GNSS signal repeater, and a high-sensitivity GNSS receiver.The innovative approach presented in this thesis facilitates the development of experimental prototypes of flexible and portable GNSS receivers and signal generators, suitable for both laboratory experiments and field testing.
  

• ORTI NAVARRO, JOAN: The Surface Defect Identification Problem in The Industry: A Novel Approach with Semantic Segmentation and Generative Adversarial Networks
  
  Author: ORTI NAVARRO, JOAN
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN AUTOMATIC CONTROL, ROBOTICS AND VISION
  Department: Department of Automatic Control (ESAII)
  Mode: Normal
  Deposit date: 18/03/2024
  Reading date: 10/05/2024
  Reading time: 11:00
  Reading place: Sala Actes de la Facultat de Matemàtiques i Estadística (FME), Campus Diagonal Sud, Carrer de Pau Gargallo, 14, 08028 Barcelona
  Thesis director: MORENO NOGUER, FRANCESC D'ASSIS | PUIG CAYUELA, VICENÇ
  Committee:
       PRESIDENT: SERRATOSA CASANELLES, FRANCESC ASSIS
       SECRETARI: GRAU SALDES, ANTONI
       VOCAL: VENTURA ROYO, CARLES
  Thesis abstract: Surface inspection of coated surfaces in the automotive industry, traditionally has been a manual process in charge of keen eye operators in charge of inspecting the whole car body. However, as might be deducted, manual inspections often lack repetitiveness and reliability, very much desired in a such a strict sector. Computer vision tackled this problem with the first automated defect detection systems, pinpointing the defects in the car body and their size. Nevertheless, as these systems are constrained to just detection, the operator is still in charge of properly labelling the defects to rework them correctly. Additionally, there is a lack of traceability between the process and the defects themselves, taking longer to identify the root causes of faulty paint shop facilities.In this thesis, we address the multidisciplinary problem of defect identification in specular surfaces, with two main research lines. In the first one, we developed a novel illumination approach based on indirect diffuse lighting, in contrast with the conventional specular reflection. Together with a high resolution camera, we demonstrated an important improvement in terms of defect recognition with respect to the existing defect detection systems. These results are assessed with specialized auditors from the SEAT Martorell factory.The second research line, oriented to computer vision, explore the possibilities of implementing a deep learning solution for industrial defect identification. We developed a fast and reliable context aggregation model, featuring dilated convolutions and residual connections between opposite layers. This model is then trained following a loss leverage between classification and segmentation, for a smoother training procedure. Additionally, in order to cope the frequent class imbalances in the industrial datasets, we developed a guided-crop image augmentation strategy, based on cropping real defect randomly into non-defective images to generate synthetic new samples. The results state that the combination of this model with this augmentation strategy is able to outperform well-known segmentation models.Eventually, for data scarcity situations, we resorted to image synthesis methods to generate new fake samples. Models like Pix2pix have proven to be able to generate close to real im- ages, helping the segmentation model to converge faster than with the previous guided-crop image augmentation technique. Later, this generative method will be surpassed by a more sophisticated one, which features spatially-adaptive normalization layers that help to synthe- size images even without an encoder. Overall, it demonstrated good capabilities in multiple industrial datasets.
  

Reading date: 14/05/2024

• AGUILAR MORENO, MIGUEL: Liquid-Liquid membrane contactors for sustainable ammonia recovery and valorization: experimental insights, novel approaches and applications
  
  Author: AGUILAR MORENO, MIGUEL
  Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
  Programme: DOCTORAL DEGREE IN CHEMICAL PROCESS ENGINEERING
  Department: Department of Chemical Engineering (EQ)
  Mode: Normal
  Deposit date: 16/04/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: CORTINA PALLAS, JOSE LUIS | VALDERRAMA ANGEL, CESAR ALBERTO
  Committee:
       PRESIDENT: DOSTA PARRAS, JOAN
       SECRETARI: GIBERT AGULLO, ORIOL
       VOCAL: REZAKAZEMI, MASHALLAH
  Thesis abstract: This comprehensive research represents a significant stride in the exploration of innovative strategies aimed at enhancing ammonia recovery within diverse wastewater streams. The study is structured into distinct phases, each addressing crucial aspects of the ammonia recovery process. In the initial phase, the research focuses on augmenting membrane contactor performance, employing coagulation-flocculation (C/F) and aeration as preliminary treatments. The outcomes of this phase demonstrate substantial increases in both the mass transfer coefficient and overall efficiency ofammonia recovery, particularly notable when treating the real sidestream centrate. A pivotal finding underscores the efficacy of dosing aluminum sulphate (Al2(SO4)3) at 30 mg Al+/L in the C/F process, yielding remarkable efficiencies in the removal of chemical oxygen demand (COD), turbidity, and total suspended solids (TSS). Into the second phase, the study delves into the sustainable application of liquid-liquid membrane contactors (LLMC) for ammonia recovery. An array of experimental conditions is meticulously explored, with the results illuminating the considerable impact of replacing the acid washing liquid between steps on the overall performance of the LLMC. Additionally, the study highlights the nuanced relationship between the initial ammonia concentration and the subsequent recovery, providing valuable insights. This phase effectively showcases the potential versatility and efficiency of LLMCs in the valorization of ammonia within wastewater streams. The third and final phase introduces a novel asymmetric hollow fiber liquid-liquid membrane contactor (HF-LLMC) with distinctive selectivity for ammonia over water. The investigation entails a comprehensive examination of various operational parameters, including feed and acid flow rates, mass transfer coefficients, and acid consumption. Notably, the results affirm the high selectivity of the HF-LLMC for ammonia, coupled with minimal water transfer. This establishes the HF-LLMC as a promising technology for the recovery and concentration of ammonium in diluted urban and industrial streams. The amalgamation of these findings, approached with a global perspective, significantly contributes not only to the advancement of sustainable nutrient recovery technologies but also underscores their pragmatic feasibility for implementation within the frameworks of the circular economy and efficient resource management.