Doctoral School

Reading date: 28/07/2026

• GARCIA RIVERA, JUAN PABLO: ESTUDIO EXPERIMENTAL DE LA CONFLUENCIA DE LOS RÍOS TOLTÉN Y ALLIPÉN (CHILE): RESULTADOS HIDRODINÁMICOS
  
  Author: GARCIA RIVERA, JUAN PABLO
  Programme: DOCTORAL DEGREE IN CIVIL ENGINEERING
  Department: Barcelona School of Civil Engineering (ETSECCPB)
  Mode: Normal
  Deposit date: 20/05/2026
  Reading date: 28/07/2026
  Reading time: 10:30
  Reading place: UPC Campus Nord, ETSECCPB, C/ Jordi Girona 1-3, edificio C1, Sala 002, Barcelona
  Thesis director: MARTÍN VIDE, JUAN PEDRO | FERRER BOIX, CARLES
  Thesis abstract: This thesis was motivated by the need to understand the hydrodynamic behavior of the confluence of the Toltén and Allipén rivers (Chile), where a bedload measurement campaign was conducted over 90 days in 2013 using a Helley-Smith sampler. During this campaign, gravel and sand transport was recorded with a non-uniform transverse spatial distribution in the measurement section (transect), referred to in this thesis as section 9. However, the lack of simultaneous hydrodynamic measurements prevented the establishment of cause-and-effect relationships between flow and sediment transport distribution.During the field campaign, individual and total flow rates were also recorded, with values ​​between 180 and 900 m³/s. This information served as the basis for developing experimental scenarios in the physical model.The overall objective of this thesis was to understand the hydrodynamic behavior (three-dimensional velocity field) of this confluence in order to identify patterns that can be generalized to confluences with similar characteristics. The physical model was constructed in the Hydraulics Laboratory of the University of Piura (Peru), with a geometric scale of 1:57.9 defined, conditioned by spatial constraints of the model site. The range of flow rates tested in the model varied between 7.7 and 32.8 l/s.The experiments were designed considering different flow combinations, characterized by a Q_tributary/Q_main flow ratio, whose values ​​ranged between 0.33 and 3.97.The experimental campaign included the calibration of triangular weirs for flow control and the definition of boundary conditions through one-dimensional modeling, using information from the prototype.Sixteen cross-sections were measured, with special emphasis on sections 6, 8, 9, and 11, near the reference transect. A total of 1641 three-dimensional velocity measurements (u, v, w) were taken, recorded at 25 Hz for 120 seconds per point, generating more than 3000 data points per measurement.Data processing was performed in Matlab using proprietary algorithms that included correlation and noise filtering (AADV and CADV), application of the Space-Phase Thresholding method, and Wavelet decomposition. The latter allowed the signal to be separated into low-frequency components (pulsations) and high-frequency components (turbulent fluctuations), facilitating a more in-depth analysis of the flow's temporal structure.Additionally, low-frequency pulsations were identified in each measurement; over a 2-minute period, these pulsations were observed to repeat 6 times. The application of dyes visually confirmed these periodic mixing patterns.From the three-dimensional velocity field, different stress components were estimated: Reynolds stress, low-frequency stress, total stress, cross stresses, and near-bottom stresses. The stresses obtained were compared with the critical stress at the onset of movement for a dimensionless Shields parameter of 0.03 (sands and gravels), allowing the identification of potential bed mobilization zones.Finally, the main contribution of this thesis lies in the detailed experimental characterization of the three-dimensional hydrodynamic field at a confluence with morphological unconformity, through the direct measurement of the three instantaneous velocity components and the analysis of their fluctuations. The results obtained provide physical and methodological criteria transferable to the study of river confluences with similar geometric and hydraulic characteristics.
  

• KOMARIZADEH ASL, SEYED MAHYAD: Real-Time Temperature-Compensated Atmospheric Corrosion Monitoring at Low Cost: The CORTEX System and a Validated IoT Framework for Structural Health Monitoring
  
  Author: KOMARIZADEH ASL, SEYED MAHYAD
  Programme: DOCTORAL DEGREE IN CONSTRUCTION ENGINEERING
  Department: Department of Civil and Environmental Engineering (DECA)
  Mode: Normal
  Deposit date: 01/07/2026
  Reading date: 28/07/2026
  Reading time: 11:00
  Reading place: UPC Campus Nord, ETSECCPB, C/ Jordi Girona 1-3, edific C2, Sala 212 (Sala Conferències), Barcelona
  Thesis director: TOSIC, NIKOLA | TURMO CODERQUE, JOSE
  Thesis abstract: Civil infrastructure forms the physical substrate of contemporary economic activity, yet the metallic components of its load-bearing skeleton are continuously deteriorating under atmospheric attack at an annual cost approaching 3 to 4 percent of gross domestic product in every industrialized economy. Despite this scale, approximately 98 percent of the global bridge inventory is currently assessed exclusively through periodic visual inspection rather than continuous instrumented monitoring. Electrical resistance (ER) measurement has been the proven standard for service-condition corrosion monitoring in the petroleum industry for decades, but its adaptation to civil infrastructure has been obstructed by the cost of the dedicated commercial data-acquisition systems required to interrogate the probes, priced between 1,800 and 11,700 US dollars per channel.This dissertation develops and validates a low-cost open-source alternative. The Low-cost Electrical Resistance Ohm analYzer (LEROY), developed in the early phase of the doctoral program, achieved 7 to 30 microohm practical resolution on Arduino-class hardware and was validated against gravimetric mass loss within 3.31 percent over a 125-day accelerated test. The LEROY testing program also quantified why basic Arduino-class hardware cannot handle the temperature dependence of resistance under continuous field conditions and confined such hardware to static readings.Virtually every commercial ACM instrument addresses the temperature problem in hardware, by adding a coated reference probe. The strategy is structurally fragile because the reference probe's thermal mass and surface heat-transfer characteristics differ from those of the exposed active probe, producing phase-dependent compensation errors precisely when temperature is changing most rapidly. The central scientific decision was to address the temperature problem algorithmically: to eliminate the reference probe entirely and reformulate compensation as a real-time firmware operation grounded in the solid-state physics of metallic resistivity. This led to the CORrosion Temperature EXpert (CORTEX) system, the central technical contribution of the dissertation and the subject of European Patent Application EP25382628.CORTEX integrates an 18-bit delta-sigma ADC co-designed with a 156.23 mA precision current source so that one least significant bit corresponds to 0.1 milliohm, a four-wire Kelvin signal path, and an SHT35 digital temperature sensor co-located with the probe. A 12-stage autonomous firmware pipeline executes a real-time temperature compensation algorithm derived from first principles and validated across a 30-test program spanning laboratory, field, and isothermal regimes. The temperature coefficient was confirmed as a stable AISI 1010 material property (mean 0.448 plus or minus 0.007 percent per degree Celsius); the thermal lag was shown to be environment-dependent. Allan deviation analysis per IEEE Std 952-1997 established a field detection limit of 0.038 ± 0.009 μm (3σ). The platform completed 22.4 days of autonomous IoT-enabled field deployment in Barcelona with energy neutrality maintained by a 100 W solar panel.The dissertation closes with an accelerated wet-and-dry cycling campaign per ASTM G44 over 11 days, in which AISI 1010 probes were subjected to alternating immersion in 3.5 weight-percent NaCl electrolyte. The corrosion-progression measurement obtained from the temperature compensation algorithm, after correction for partial-immersion geometry and time-of-wetness scaling, reconciled with the independent ASTM G1 gravimetric mass-loss measurement to within 2.0 percent under ISO 9223 Category CX exposure. The work supports the central claim that a low-cost open-source framework can deliver commercial-grade quantitative atmospheric corrosion monitoring of metallic civil infrastructure.
  

• MONTALÀ PALAU, MONTSERRAT: Resilience in Power Systems: From Technology to System-Level Perspectives
  
  Author: MONTALÀ PALAU, MONTSERRAT
  Programme: DOCTORAL DEGREE IN ELECTRICAL ENGINEERING
  Department: Department of Electrical Engineering (DEE)
  Mode: Normal
  Deposit date: 17/06/2026
  Reading date: 28/07/2026
  Reading time: 10:00
  Reading place: Aula Capella - ETSEIB-UPC
  Thesis director: GOMIS BELLMUNT, ORIOL | CHEAH MAÑÉ, MARC
  Thesis abstract: This thesis is structured around a concept that has recently been linked to electrical systems: resilience. These systems have become fundamental for the functioning of modern societies, and, for this reason, it is necessary to continue transforming them while ensuring their proper operation. This thesis addresses the concept of resilience in electrical systems from two complementary perspectives. The first focuses on the development of a methodology, implemented in an open-source tool, that allows the assessment of the power system resilience and the analysis of how the deployment of different technologies can modify it. The second focuses on specific technologies and is articulated around the concept of ramp rate limit. Regarding the first part, the concept of resilience in electrical systems is relatively recent and has emerged to overcome the limitations of the traditional concept of reliability. Resilience aims to consider a wide range of events that may affect the electrical system, including those with low probability but high impact, and to quantify their consequences in energy, social, and economic terms. Although the concept of resilience has been incorporated into new policies, roadmaps, and technological developments, its measurement and quantification remain a challenge.In this context, the development of resilient electrical systems requires both the collection of data on current systems and the identification of possible future events that may affect them. This makes it necessary to have methodologies capable of integrating and evaluating this information in a coordinated manner. To address this challenge, the thesis proposes a methodology that combines traditional tools for the analysis of electrical systems, such as Optimal Power Flows (OPF), with Geographic Information Systems (GIS). In this approach, resilience is quantified in terms of the total energy at risk in a given power system when exposed to specific hazards. This methodology has been implemented in a tool whose objective is to facilitate its use with basic electrical knowledge, so that it can be used by a wide range of users. As for the second part, the ramp rate limit, adopted by several countries, is defined as a strategy to control the speed of variations in the rate of change of active power from generation plants, mainly wind and photovoltaic solar plants. In addition, since renewable plants may operate without dedicated voltage control and at constant power factor, limiting active power variations also slows down reactive power changes, giving the system additional time to activate alternative voltage control resources.Despite its relevance, the implementation of ramp rate limits continues to represent a challenge for the different agents of the electrical system. In this sense, the thesis proposes a methodology that allows system operators to determine the required ramp rate limit based on system parameters such as inertia, damping, and response time constants. Likewise, a methodology is presented for renewable energy plant developers to design installations that comply with these requirements. Since this often involves the incorporation of energy storage systems, the proposed methodology is flexible and allows the exploration of the use of different storage technologies.Each section includes case studies that have allowed for the validation of the robustness of the developed methodologies and tools, showing how different strategies and technologies affect the resilience and stability of the electrical system.Overall, this doctoral thesis makes a significant contribution to the development of resilient electrical systems, aiming to ensure their proper functioning and, in doing so, to support life and essential activities in contemporary societies.
  

• VILELLA VEGA, MANEL: Enhanced modulation strategies for a high-efficiency energy conversion system for electric vehicles
  
  Author: VILELLA VEGA, MANEL
  Programme: DOCTORAL DEGREE IN ELECTRONIC ENGINEERING
  Department: Department of Electronic Engineering (EEL)
  Mode: Normal
  Deposit date: 22/04/2026
  Reading date: 28/07/2026
  Reading time: 11:00
  Reading place: Sala de Conferències (TR1-085), campus de Terrassa
  Thesis director: ZARAGOZA BERTOMEU, JORDI | BERBEL ARTAL, NÉSTOR
  Thesis abstract: The global transition toward electric vehicles (EVs) has intensified the demand for high-efficiency power electronics. On-Board chargers (OBCs) and bidirectional energy conversion systems are essential to manage the flow between the grid and the vehicle battery. These systems must be compact, lightweight, and capable of high-power density to satisfy modern automotive requirements. In this context, isolated bidirectional DC-DC conversion, specifically the Dual Active Bridge (DAB) converter, has emerged as a key technology due to its inherent galvanic isolation and high performance. To achieve high power density and efficiency, this research utilizes WBG semiconductors, specifically GaN devices, which allow for higher switching frequencies compared to traditional silicon.The primary objective of this doctoral work is to optimise control and modulation techniques to exploit the full potential of GaN semiconductors while mitigating high-frequency operation challenges, such as parasitic effects, thermal management, and EMI. The research is structured around four main contributions.First, the thesis experimentally evaluates a GaN-based non-resonant DAB converter, analysing the trade-offs between switching frequency, efficiency, and EMI. It demonstrates that increasing the switching frequency up to 200 kHz maintains high efficiency while enabling a significant reduction in the size of passive components without compromising electromagnetic compatibility.Secondly, a mathematical quantification of the steady-state DC current in non-resonant DAB converters is introduced. The formulation, which accounts for semiconductor resistance variations and timing mismatches, is validated experimentally and coupled with a closed-loop voltage compensation control strategy to effectively mitigate these parasitic DC currents.Thirdly, a variable frequency modulation is developed to reduce transient surge currents during start-up and load variations. Finally, the thesis explores the modular series-parallel connection of converters to scale the system for different EV battery voltages.
  

• ÁLVAREZ ROBERT, DAVID: On the co-design of runtimes, systems and programming interfaces for HPC
  
  Author: ÁLVAREZ ROBERT, DAVID
  Programme: DOCTORAL DEGREE IN COMPUTER ARCHITECTURE
  Department: Department of Computer Architecture (DAC)
  Mode: Normal
  Deposit date: 25/06/2026
  Reading date: 28/07/2026
  Reading time: 11:30
  Reading place: Sala d'Actes de la FIB, Edifici B6, planta 0, Campus Nord UPC
  Thesis director: BELTRAN QUEROL, VICENÇ
  Thesis abstract: High-performance computing (HPC) platforms are evolving towards increasingly complex architectures: many-core CPUs with multi-level NUMA hierarchies, heterogeneity with multiple classes of accelerators and higher-capacity interconnects. The increasing complexity and variety of resources in these machines make it harder for application programmers to use them efficiently and effectively. As a result, many resources in modern HPC clusters remain underutilized, limiting energy efficiency and the potential throughput of the machine.This thesis argues that addressing these challenges requires co-design across the software stack, from runtime mechanisms and programming interfaces to system-level policies. We first study task-based runtimes and identify opportunities to reduce overheads and improve scalability on many-core machines, introducing novel scheduling and dependency-management techniques that maintain throughput under extreme concurrency. We then tackle programmability and performance in heterogeneous systems, proposing runtime and interface support to better overlap data movement, accelerator offloading, and CPU computation.We also make a case for the effective co-design of applications and programming models through the study of an increasingly common application class: iterative data-flow computations, commonly used in simulations, iterative solvers, and AI. Through this study, we propose specific optimizations for this application class, showing how holistic co-design approaches can lead to significant speedups.Finally, we present the nOS-V library with the goal of improving system-wide utilization through application co-scheduling, and we later apply the same methodology to obtain truly interoperable programming models, enabling multiple runtimes and parallel libraries to coexist within a single application with reduced mutual interference.Overall, the contributions of this thesis provide a set of runtime techniques, programming abstractions, and system mechanisms that jointly improve throughput, efficiency, and composability on next-generation HPC systems.