Author: IVANOVA, ANZHELIKA
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 STATISTICS AND OPERATIONS RESEARCH
Department: Department of Statistics and Operations Research (EIO)
Mode: Normal
Deposit date: 16/05/2023
Reading date: pending
Reading time: pending
Reading place: pending
Thesis director: CORCHERO GARCIA, CRISTINA | DOMÍNGUEZ GARCÍA, JOSÉ LUIS
Committee:
     PRESIDENT: KRKOLEVA MATESKA, ALEKSANDRA
     SECRETARI: VILLAFÁFILA ROBLES, ROBERTO
     VOCAL: COMECH MORENO, MARIA PAZ
Thesis abstract: The smart grid concept in distribution networks has risen due to the ICT trend, with the transformation of the network into an active one, incorporating many different smart grid technologies. One of the main components that can allow this to happen is the monitoring system that includes measurement devices, sensors and automation. Due to the topological and electrical characteristics of the distribution networks, the need to reduce costs presents an issue and sensors and automation devices cannot be placed at each point of the network. This causes the network to have unmonitored parts, which leads to the need to optimize the placement of sensors (Phasor Measurement Units) and perform state estimation to ensure the most optimal monitoring and control scheme. The placement of measurement devices such as the PMUs, improves observability and controllability of the distribution network and enables new features of grid operation. These new features should make the network resilient so that the service disruption for the end users after a contingency event is minimized as much as possible. This can be achieved through two main methods, network reconfiguration by modifying the electricity path to isolate the faulty line or equipment, or by allowing islanded/disconnected operation of some parts of the network. The distributed generation aids the islanded operation by providing the needed power supply in the islanded parts of the distribution network. Another important aspect for the Distribution System Operators when reconfiguring the grid to deal with faults is to maintain observability of the network. This means that in following an intentional islanding process, it is important to have monitoring devices in each island, so that the operators do not lose the monitoring and controlling capabilities within the created islands. The approach to solve the previously explained problems depends on the type of distribution network. These can vary in topology depending on the voltage level. Medium voltage distribution networks have predominantly weakly-meshed structures that can be operated in radial mode, whereas low voltage distribution networks have radial structures. This difference in topologies means two different research directions. Therefore, the research in this thesis focuses on the medium-voltage distribution networks. The presented seemingly different problems are strongly interconnected within an active distribution network. As part of this work, the lack of an integrated approach to solving these complex problems has been identified, especially within medium-voltage networks. Therefore, the main contribution of this thesis is to present integrated approaches to solving these problems by: analysing the different solution techniques and testing the relevant ones on the chosen networks, developing processes to assess the interdependence of the different solution techniques and developing a new tool that helps the intentional islanding process after a fault that takes into account the observability of the formed islands. Keywords: optimal PMU placement, state estimation, intentional islanding, medium voltage networks

Author: OJAGHI KAHJOGH, BEHNAM
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: 16/05/2023
Reading date: pending
Reading time: pending
Reading place: pending
Thesis director: ADELANTADO FREIXER, FERRAN | VERIKOUKIS, CHRISTOS
Committee:
     PRESIDENT: PALAU SALVADOR, CARLOS ENRIQUE
     SECRETARI: SANCHEZ GONZALEZ, JUAN
     VOCAL: GELABERT DORAN, XAVIER
Thesis abstract: The main objective of this thesis is to propose solutions for implementing dynamic RAN slicing and Functional Split (FS) along with MEC placements in 5G/B5G. In particular, this thesis is divided into three parts. In the first part (Chapter 3), we model a joint slicing and FS optimization in the 5G RAN with the objectives of optimizing the centralization degree and throughput.In this work, the RAN slicing allowed a customized FS deployment per slice, thus optimizing the available resources, e.g., transport network capacity and Remote Radio Head (RRH) or Central Unit (CU) computational capacity. Next, we present the second part in Chapter 4 by extending the first work by proposing SlicedRAN: service-aware network slicing framework for 5G RAN to create isolated RAN slices based on the service requirements with customized functional splits per slice. The proposed framework investigates the bottlenecks in the capacity of RRHs Fronthaul/Backhaul (FH/BH) network capacity along with a minimum level of Service Level Agreement (SLA) for each slice imposed by the different service types. Finally, in the last part presented in Chapter 5, we investigate dynamic RAN/MEC slicing framework in Open-RAN (O-RAN) architecture to dynamically place the RAN protocol stack of Virtual Network Functions (VNFs) and MEC server per slice. This framework contains the bottlenecks in the capacity of Open-RAN Radio Units (O-RUs), MEC server computation capacity, together with a customized FS per slice, to jointly solve the challenge of operating cost-efficient edge networks and maintaining the served traffic with various QoS criteria. We use a robust Benders decomposition algorithm, which reduces the computation complexity while ensuring an exact and optimal global solution. The proposed algorithm successfully optimizes the joint throughput and system cost in various traffic scenarios while satisfying QoS criteria, as shown by trace-driven simulation results. Hence, in order to determine the right MEC settings for on-demand traffic and alter the MEC type to satisfy the QoS requirements of various User Equipment (UEs) belonging to different slice types, we explore the compute and storage capacity for MEC services such as Enhanced Mobile Broadband (eMBB) and ultra-Reliable and Low-Latency Communications (uRLLC). The overall conclusion of the present findings demonstrates a trade-off between the throughput attained and the cost incurred to the network. As a result, we investigate multi-objective optimization to construct slices while optimizing throughput and decreasing computational cost objectives, and we compare its performance to that of a single objective (maximizing throughput). The findings demonstrate that a throughput increase of up to 160% can be made possible by increasing 78% in the computation cost for a single objective when compared with multi-objective without prioritization. In addition, comparing a single objective with a multi-objective with priority in throughput, it increases throughput by up to 82% and adds 17% to computation costs. Consequently, a single objective of maximizing throughput can result in high throughput at the expense of high cost. It is possible to achieve almost half the amount of throughput using multi-objective with prioritization in throughput, whereas costs can be reduced five-fold.

Author: JIMÉNEZ ROJAS, JORGE IVÁN
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: 11/05/2023
Reading date: 14/06/2023
Reading time: 11:00
Reading place: Institut de Robotica IRI, sala de reunions 8, Campus Sud, Facultat de Matemàtiques i Estadistica (FME), c/ Pau Gargallo, 14, 08028-Barcelona
Thesis director: GRAU SALDES, ANTONI | PADILLA ARANDA, CRISTÓBAL
Committee:
     PRESIDENT: PALACÍN ROCA, JORGE
     SECRETARI: SANFELIU CORTES, ALBERTO
     VOCAL: GUBERMAN, DANIEL
Thesis abstract: Nowadays, mercury-cadmium-telluride (MCT) short-wave infrared (SWIR) detectors are widely used in cutting-edge spacemissions and ground-based telescopes. They take advantage of the fact that the dust and gases in the deep-sky are almosttransparent to most of the infrared spectrum, allowing redshifted light from the farthest and youngest universe to be easilydetected.Despite the maturity of the infrared technology, large focal plane arrays (FPAs) (> 4 million pixels) are still under development. Toadvance in this technology, the H2020-COMPET program funded the ASTEROID project, which aims to develop a largeEuropean-made MCT FPA of 2k x 2k and 15 µm pixel pitch. The key to success for such a breakthrough development relies onthe hybridization reliability between the MCT and the readout electronic circuit (ROIC). This process is performed using indiumbumps but, due to the different coefficient of thermal expansion and the fact that the ASTEROID FPA is operated at 100K, itcauses plastic and elastic deformations in the whole assembly, thus leading to potential hybridization failures.Then, how the temperature and the thermal stress are affecting the performance of a large MCT FPA? To get an answer to thisquestion, two setups were built: a cryo-vacuum setup with capabilities to perform several thermal cycles on the resultingASTEROID FPA and an optical setup designed to illuminate the detector while it is thermally stressed. The FPA under test wasthermally cycled 30 times between 293K and 50K. The cycle starts at room temperature (293K), then the FPA is cooled down to100K, the temperature at which the detector is illuminated and the images captured. Afterward, the FPA is cooled down to 50Kand the cycle ends with the FPA temperature at 293K before starting a new cycle.During the cryo-vacuum setup development, the cryostat temperature stability demanded special attention due to the huge massof the inner parts and the opto-mechanical pieces. After control and thermal simulations, a temperature stability of <0.5 mK wasreached at every stationary setpoint (293K, 100K and 50K) while the temperature slew rate was kept around 0.5 K/min.Concerning the optical setup, it was developed to cover the whole ASTEROID wavelength range with monochromatic light insteps of 10 nm. A quartz-tungsten-halogen (QTH) stabilized lamp was used, which is collimated and single wavelengths wereselected through an astigmatism-corrected Czerny-Turner monochromator. The light was homogenized using a low emissivitygold-coated integration sphere installed at the cryostat entrance window. Inside the cryostat, the optical path was extendedthrough a light baffle and a short-pass filter, both cooled below the detector temperature in order to reduce the thermal radiation.The ASTEROID FPA has been developed using a custom pixel configuration in such a way that two pixel levels are identified:¿blind¿ and ¿active¿. They were spread out and intermingled along the whole FPA forming a kind of ¿chessboard¿ with pixelvalues separated by ~10 kADU. Furthermore, some extra complexity to the clustering process was added due to the FPA has 32output channels, each with a unique offset level. To binarize the images, up to four classification and thresholding algorithmswere tested and compared to each other, to finally select the best one concerning low detection error and the highest success toresolve pixel failures.Finally, the detector degradation due to thermal stress was measured by counting the number of damaged pixels on everythermal cycle during almost one month, demonstrating that the novel ASTEROID FPA and its hybridization process is minimallyaffected by the temperature stress, being the number of damaged pixels negligible.

Author: OUZERI, ADAM AMINE
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: 02/05/2023
Reading date: 14/06/2023
Reading time: 16:30
Reading place: Sala d'Actes de l'FME, Edifici U, Campus Sud
Thesis director: ARROYO BALAGUER, MARINO
Committee:
     PRESIDENT: JOANNY, JEAN FRANÇOIS
     SECRETARI: SAEZ VIÑAS, PABLO
     VOCAL: FOUCHARD, JONATHAN
Thesis abstract: Epithelial monolayers perform a variety of mechanical functions, which include maintaining a cohesive barrier or developing 3D shapes, while undergoing stretches over a wide range of magnitudes and loading rates. To perform these functions, they rely on a hierarchical organization, which spans molecules, cytoskeletal networks, adhesion complexes and junctional networks up to the tissue scale. While the molecular understanding and ability to manipulate cytoskeletal components within cells is rapidly increasing, how these components integrate to control tissue mechanics is far less understood, partly due to the disconnect between theoretical models of subcellular dynamics and those at a tissue scale. To fill this gap, here we propose a formalism bridging active-gel models of the actomyosin cortex and 3D vertex-like models at a tissue scale. We show that this unified framework recapitulates a number of seemingly disconnected epithelial time-dependent phenomenologies, including stress relaxation following stretch/unstretch manoeuvres, active flattening after buckling, pulsatile non-affine contractions, curling, or active superelasticity. We further apply the proposed modelling framework to understand and predict the mechanics and reshaping of 3D epithelia in the context of epithelial domes. More specifically, we examine the effect of size, shape and deformation rate on the mechanics of pressurized cell monolayers. We show how the active viscoelasticity of the actomyosin cortex enables the directed folding of rapidly deflating domes into pre-defined buckling patterns. Overall, the proposed framework systematically connects subcellular cortical dynamics and tissue mechanics, and ties a variety of epithelial phenomenologies to a common sub-cellular origin.

Author: BERTRAN OLLER, ORIOL
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: 18/05/2023
Reading date: pending
Reading time: pending
Reading place: pending
Thesis director: FERNANDEZ GARCIA, DANIEL | RODRIGUEZ ESCALES, PAULA FELICIDAD
Committee:
     PRESIDENT: PEDRETTI, DANIELE
     SECRETARI: SAALTINK, MAARTEN WILLEM
     VOCAL: POOL RAMIREZ, MARIA
Thesis abstract: Groundwater is now under high stress levels and its quality and quantity arise as one of the most interesting and necessary topics our community should address. This doctoral thesis is focused on the quality of the groundwater: from the study of chemical reactions in laboratory experiments, necessary for the biodegradation of harmful organic pollutants to occur, to the design of an engineered method to promote reactions in the field scale. Chemical reactions are induced by the mixing between two different waters, so understanding and predicting this phenomena become crucial to accurately forecast reactive transport and groundwater remediation. Sharp interfaces and heterogeneity in porous media play a significant role in controlling mixing. This thesis aims to investigate the influence of a sharp interface on mixing through laboratory experiments. The experiments were conducted using laboratory columns filled with a bilayer distribution scheme of coarse-fine glass beads, and for comparison, two homogeneous distributions. To examine the distinct characteristics of transport and chemical reactions associated with a sharp interface, the evolution of mass concentration and spatial moments of a colored product across these bilayer systems was studied. This colored product is formed when two colorless reactants are mixed and serves as a direct indicator of mixing. Quantification of this product was achieved through image analysis. The results obtained from these experiments concluded that coarse-to-fine transitions tend to promote and enhance solute reactivity in heterogeneous systems compared to fine-to-coarse transitions, leading to increased reaction rates and mass production. Furthermore, an asymmetrical response in transport was observed through the analysis of higher-order spatial moments of the concentration distributions. Additionally, it was found that analytical solutions based on the advection-dispersion equation successfully matched the actual arrival times recorded by both images and flow outlet samples. However, these solutions failed to simulate the complexities associated with a two-layer reactive transport system that includes an interface.Mixing is an essential phenomenon for chemical reactions to occur and for achieving successful outcomes in the context of in-situ groundwater remediation. However, natural attenuation alone often results in a slow mixing process. Some authors have addressed this issue by employing an Engineered Injection-Extraction (EIE) system. EIE has been proven as an effective method to promote the dilution of treatment solutions, facilitating the mixing between these solutions and the contaminated groundwater. This enhanced mixing facilitates chemical reactions, which, in turn, lead to the biodegradation of pollutants. However, existing studies on the subject have not considered the potential impact of connectivity and preferential flow-paths. Since preferential flow-paths can mainly carry the fluid, limiting the mixing and chemical reactions, neglecting the presence of these high-permeable channels can lead to an overestimation of EIE's capabilities. In this doctoral thesis it has been studied the capabilities of EIE system to dilute a treatment solution in both poorly-connected and highly-connected fields. The approach involves determining an optimal stirring protocol, tailored to each specific medium, which maximizes the mixing process. Metrics are proposed to measure both the extent of mixing and the containment of the treatment solution within the remediation volume. Additionally, particle trajectories are analyzed to assess if preferential flow paths are disrupted. The results obtained from these metrics show that the effectiveness of EIE in enhancing mixing remains consistent, irrespective of the presence of preferential flow paths. This study demonstrates that using EIE with rotating dipoles reduces the uncertainty in remediation outcomes caused by medium heterogeneity.