Doctoral School

Reading date: 02/07/2024

• ARNAIZ MARTÍNEZ, DAVID MARIANO: Bringing Self-Awareness to the Extreme Edge - A Distributed Approach for Adaptive Energy Management in WSNs Applied to Structural Health Monitoring
  
  Author: ARNAIZ MARTÍNEZ, DAVID MARIANO
  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: Normal
  Deposit date: 21/03/2024
  Reading date: 02/07/2024
  Reading time: 11:00
  Reading place: Defensa: Aula de postgrau, edifici C5, Campus Nord, ETSETB
  Thesis director: ALARCON COT, EDUARDO JOSE | MOLL ECHETO, FRANCESC DE BORJA | VILAJOSANA GUILLEN, XAVIER
  Committee:
       PRESIDENT: CHOWDHURY, KAUSHIK ROY
       SECRETARI: ABADAL CAVALLÉ, SERGI
       VOCAL: DINI, PAOLO
  Thesis abstract: In today's landscape, data are increasingly becoming an invaluable resource to enhance decision-making, enable predictive insights, improving operational efficiency, among numerous other applications. Within the current data-centric mindset, wireless sensors play a facilitator role, allowing the collection of data in a flexible, low-cost, and simple-to-deploy way.One of the ever-pending challenges of wireless sensor node technologies is their limited energy availability, particularly their limited battery life. To extend their battery life, sensor nodes need to use their energy as frugally as possible. The optimal behavior for a sensor node is highly dependent on the varying operation conditions. Thus, to operate optimally, sensor nodes need to incorporate adaptive mechanisms to dynamically adjust their behavior at runtime. These adaptive mechanisms are commonly referred to as Dynamic Energy Management (DEM).Despite the progress made in DEM, commercial sensor nodes continue to mostly operate using static behaviors, wasting energy. The main limitation impeding the widespread adoption of DEM is that it renders the node's behavior dependent on the operating conditions, thereby making the node's behavior unpredictable. In recent years, self-awareness has been proposed as a promising solution to this challenge. Self-aware systems autonomously adjust their behavior at runtime based on their internal and external operating conditions to achieve their operational goals as efficiently as possible. Consequently, while the behavior of a self-aware system may not be known at a given time, these systems provide some level of predictability by complying with their operational goals.This thesis delves into the use of self-awareness at the sensor node level to guide the node's adaptive behavior. The main objective of this thesis is to provide a solid foundation to support future progress in self-aware sensor nodes. In pursuit of this goal, it presents a reference architecture of a self-aware sensor node solving the existing lack of standardization in their design. Additionally, it proposes two self-aware monitoring methods enabling the node to comply with its battery lifetime target while optimizing its energy allocation to maximize its monitoring accuracy. Another key aspect that limits the adoption of self-awareness at the sensor node level is the node's lack of information and computing capabilities to model complex environments, as is usually the case in Structural Health Monitoring (SHM) applications. This thesis tackles this issue by proposing an anomaly-aware monitoring method tailored for SHM applications, which models the local vibration patterns measured by the node to determine the current monitoring requirements for the node. Finally, the thesis ends by exploring how the concept of self-awareness can be extended through the network, enabling the interaction between self-aware sensor nodes and a self-managing monitoring application running in the cloud.
  

• NASR ESFAHANI, KOUROSH: Mathematical modeling of advanced oxidation processes for the efficient wastewater treatment: Integrated Management of advanced oxidation processes and conventional Bio-Processes for the removal of recalcitrant components
  
  Author: NASR ESFAHANI, KOUROSH
  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: 28/03/2024
  Reading date: 02/07/2024
  Reading time: 11:00
  Reading place: Sala Polivalent de l'Edifici I, Planta baixa, Campus Diagonal-Besòs
  Thesis director: PEREZ MOYA, MONTSERRAT | GRAELLS SOBRE, MOISES
  Committee:
       PRESIDENT: PAIS VILAR, VÍTOR JORGE
       SECRETARI: SOLER TURU, LLUIS
       VOCAL: GARCIA MONTAÑO, JULIA
  Thesis abstract: The objective of this thesis is to contribute to the development of mathematical modeling of Advanced Oxidation Processes (AOPs) aimed at the competent treatment of recalcitrant organic compounds in wastewater. In particular, the Ph.D. thesis first focuses on developing mathematical models of AOPs, implementing these models in software tools, and enabling a deeper understanding of the complex nature of these processes through the detailed simulation of the evolution of chemical species along the reaction time for diverse and unexplored scenarios. Hence, these tools are next used for fitting the models to the experimental data obtained in the laboratory in the course of the thesis or reported in the literature. The fitted models are analyzed and refined through sensitivity analysis techniques, and finally, they are validated and their accuracy assessed. Models are mainly used for addressing operational issues, but also design aspects are considered in regard of the simulation of integrated processes using AOPs and conventional biotreatment processes.The thesis specifically addresses the development of a model for AOPs, above all photo-Fenton processes, including flexible H2O2 supply given as a function of time. The model contributes a practical tool aimed at providing model-based simulation for solving the problem of the management of the H2O2 dosage profile of the photo-Fenton process.The thesis also addresses the problem of the pH dependency of the photo-Fenton by modeling the possibility of performing the photo-Fenton process at near-neutral pH. This is studied by considering the use of iron complexing agents such as ethylenediamine disuccinic acid (EDDS). In a subsequent stage, as a step forward in improving photo-Fenton processes, a reported kinetic model of the Fe(3+)-EDDS mediated photo-Fenton process is extended to include the reactions occurring in the absence of H2O2, when EDDS(• 3- )radical generated from the lysis of the Fe(3+)-EDDS complex is responsible for the organic matter degradation. This is achieved by adopting a novel semi-empirical approach based on lumping radical species.Ozonation of wastewater is also studied as a different case of AOPs, focusing in the modeling of ozone decay during the treatment of secondary effluents containing organic matter. This is addressed by proposing a new model, based again in the used of lumped or surrogate concentrations. The ozone model developed is shown to be capable of describing the complex profile of the ozone at different initial concentrations, and has proved accurate to describe the experimental data obtained in the lab, as well as data reported in the literature.The modeling approach adopted in this thesis has also been used to explore integrated processes combining AOPs with other processes, namely conventional biotreatment processes which main acknowledged limitation is the incapacity to remove recalcitrant compounds from wastewaters. The study combined the AOP models developed with standard models such as ASM1 to map the correspondence between the variables employed in each model, and produce the simulation of different scenarios combining these two technologies.As a final remark, the thesis has also addressed the design and development of chemical reactors, particularly prototypes for photo-Fenton processes using 3D-printing. This last study addresses the selection of materials according to different criteria for reactor prototyping and subsequent testing of the chemical suitability of the reactor for carrying out AOPs.
  

• PERARNAU OLLÉ, ENRIC: Design of service-purpose-vehicles through the sense of smell
  
  Author: PERARNAU OLLÉ, ENRIC
  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: Article-based thesis
  Deposit date: 05/06/2024
  Reading date: 02/07/2024
  Reading time: 13:00
  Reading place: Defensa pública a la Sala de conferencies de l'Edifici TR1. (Terrassa)
  Thesis director: CASALS TERRE, JASMINA | FARRÉ LLADÓS, JOSEP
  Committee:
       PRESIDENT: KAUSHIK, AJEET
       SECRETARI: CUSOLA AUMEDES, ORIOL
       VOCAL: WESTERBERG, LARS-GÖRAN
  Thesis abstract: This thesis arose from the need to design new tools that enable a better control of indoor air quality in vehicles. Even though indoor air quality has been widely explored in buildings, this topic has often been overlooked by most automotive manufacturers. In recent years, especially after the COVID-19 pandemic, a better control of in-vehicle air quality has become a prominent need for most customers and operators of vehicle fleets. Traditionally, on-demand ventilation systems have used carbon dioxide (CO2) concentration to regulate indoor air quality. However, within the confined space of vehicles, the concentration of volatile organic compounds (VOCs) can also pose a real risk to the health and comfort of passengers. Therefore, in order to ensure optimal air quality conditions, it seems necessary to complement CO2 detectors with sensors that can effectively monitor VOCs. In the new era of e-mobility and connectivity, vehicles incorporate dozens of sensors in their architecture. Thus, reducing the fabrication and operational costs of new monitoring devices has become a critical requirement to justify their implementation. Recent advancements in micro-fabrication techniques and new materials have enabled the creation of VOCs sensors that are increasingly sensitive, compact, and cost-effective. However, the performance of some of these devices is still conditioned to high energy requirements during operation. In addition, the effectiveness of current gas sensors needs further improvement, so that they not only have high sensitivity, but also a certain degree of selectivity towards multiple VOCs in the environment.This thesis focuses on the design, fabrication, and implementation of a new device for the monitoring of VOCs in vehicles. The results demonstrate the suitability of integrating a gas sensor and a microfluidic channel, which exploit the unique properties of polymers for the sensitive and selective detection of VOCs at ambient temperature. First, this work evaluates the response of a gas sensor coated with single and hybrid polymer films. The addition of carbon nanoparticles within the polymer not only contributes to an increase in the sensitivity and response times of the sensor, but also helps to improve the selectivity of the polymer films. Secondly, this work evaluates the responses of a microfluidic channel for the discretization of VOCs in a mixture. The empirical results obtained in this thesis indicate that polymer thickness is critical in both the sensitivity and selectivity of the different fabricated devices. In general, thicker polymer films help to increase or optimize the performance of both, the gas sensor and the microfluidic channel. Moreover, the chemical compatibility between VOCs and the polymer also proves to be very important in the performance of both devices. For this reason, this work proposes a new methodology, based on the Hansen solubility parameters, which can help assess and predict the response of polymers for VOCs monitoring. Finally, this thesis describes the implementation of an air quality monitoring system that effectively measures CO2 and VOCs levels inside the vehicle cabin. A series of pilot tests validate that VOCs monitoring is relevant to the customer experience and the proper control of indoor air quality in vehicles. Furthermore, these activities contribute to defining how this system should be integrated with the overall vehicle and environment. To the authors knowledge, it is the first time that the devices presented in this thesis have been investigated for their implementation in vehicles, which showcase the originality and potential of this work.
  

Reading date: 03/07/2024

• LEÓN OVIEDO, TAMARA ELIZABETH: Application of bipolar electrodialysis to the generation of alkaline and acidic solutions from concentrated seawater brines from saltworks
  
  Author: LEÓN OVIEDO, TAMARA ELIZABETH
  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: 08/05/2024
  Reading date: 03/07/2024
  Reading time: 12:30
  Reading place: Defensa pública: EEBE (Escola d'Enginyeria Barcelona Est), Sala Polivalent de l'Edifici A, planta baixa, Campus Diagonal-Besòs
  Thesis director: JOFRE CRUANYES, LLUÍS | CORTINA PALLAS, JOSE LUIS
  Committee:
       PRESIDENT: GIBERT AGULLO, ORIOL
       SECRETARI: LICON BERNAL, EDXON EDUARDO
       VOCAL: PAWLOWSKI, SYLWIN
  Thesis abstract: Brines should be treated as waste and disposed accordingly. Nevertheless, brines are typically discharged back into water bodies, thereby affecting the marine environment, soil quality, and groundwater. However, the potential benefits and applications of these brines are worth further investigation. In addition to the high concentration of salt (NaCl), some important elements, such as Critical Raw Materials (e.g. Li, Sr, Ga, Ge) can be found. This has increased interest in using brines as an alternative source for recovering strategic elements, the large content of strong electrolytes (e.g., NaCl and Na2SO4) has opened the possibility of using brines as a source to produce chemical commodities (e.g., strong acid and bases). Specifically , owing to the highly saline nature of brines, they are well-suited for use in electro-membrane processes such as Electrodialysis with Bipolar Membranes (EDBM). EDBM allows for the generation of chemicals from their corresponding salts; the protons and hydroxide ions generated in the bipolar membranes generate, together with the cations and anions removed from the salts , acidic and alkaline solutions, respectively. However, EDBM technology still needs to be improved to reduce the high energy expenses and boost the concentration of products. EDBM remains a non-scale-up technology that requires more research and study to be able to compete with well-established technologies to produce acidic/alkali solutions from brines, including chlor-alkali technology.There fore, it is necessary to investigate mass transfer processes in complex systems such as those involving EDBM with solutions of high salt composition. Additionally, there are a limited number of bipolar membranes and limited information on the behaviour of the membranes in concentrated solutions .In this context, the present thesis aims to carry out an extensive evaluation of the production of acidic and alkaline solutions from brines using EDBM. This involved moving from theoretical proposals based on Computational Fluidic Dynamics (CFO) models to a comprehensive experimental campaign using synthetic brines, in which numerous operational parameters were examined. Two CFO models were introduced using 2-0 geometry, one was time-dependent and the other was not; both aimed to study the mass transpo rt, potential distribution, and water splitting phenomena.The results from both theoretical studies and experiments offered valuable insights into how to enhance the performance of EDBM and make them more competitive with current popular technologies, ultimately leading to the growth and expansion of this technology.
  

• LOPEZ BLANCO, SAMUEL: Current-controlled flash sintering for ultra-fine control of the microstructure of lead-free ferroelectric perovskites.
  
  Author: LOPEZ BLANCO, SAMUEL
  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: Article-based thesis
  Deposit date: 09/05/2024
  Reading date: 03/07/2024
  Reading time: 11:00
  Reading place: Defensa pública a l'Aula 002, Edifici C4, Jordi Girona 1- 3, Campus Nord, Barcelona
  Thesis director: GARCIA GARCIA, JOSE EDUARDO | OCHOA GUERRERO, DIEGO ALEJANDRO
  Committee:
       PRESIDENT: PEREZ MAQUEDA, LUIS ALLAN
       SECRETARI: JIMENEZ PIQUÉ, EMILIO
       VOCAL: BELTRAN MIR, HECTOR
  Thesis abstract: The global environmental crisis imposes the need to perform changes in modern industrial manufacturing systems. In the context of ferroelectric ceramics, it is required to move towards energy efficient sintering methods and eco-friendly materials. Flash sintering emerges as a potential alternative owing to its rapid densification and reduced energy consumption. This technique has been investigated in depth since its discovery in 2010 but it is yet to be fully understood. In this thesis, flash sintering is employed in order to obtain dense environmentally-friendly ferroelectric ceramics. A proper control of the sintering parameters is used to achieve highly controlled microstructures and enhanced functional properties for specific applications. The flash technique is then taken a step further by exploring the current control mode, which proves to grant further dominion over the microstructure. In this work a comprehensive study of sintering parameters in multiple ferroelectric materials, from well-known compositions to complex perovskite-structured systems, is performed in order to accomplish fine microstructure tailoring. The ultimate goal was to demonstrate that flash sintering is an efficient method of obtaining ferroelectric polycrystals with high quality properties that can rival their conventional counterparts while overcoming the aforementioned environmental concerns.