Doctoral School

Reading date: 07/05/2025

• RODRIGUEZ CALVET DE MAGALHÃES, JOSÉ EDUARDO: Alfred Grenander. Transitional spaces and the mobility infrastructure of Berlin from 1914 to 1930
  
  Author: RODRIGUEZ CALVET DE MAGALHÃES, JOSÉ EDUARDO
  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 DESIGN
  Department: Department of Architectural Design (PA)
  Mode: Normal
  Deposit date: 07/04/2025
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: FERRER FORES, JAIME JOSE
  Thesis abstract: The city of Berlin owes the design of most of its subway stations to the Swedish architect Alfred Grenander, who was the main responsible for this task in the beginning of the 20th century. These subway stations, which can be seen as a ‘specialized building type', contributed to the transformations in the urban fabric progressively shifting the urban connections, at the same time that they provided a specific architectural language, through the creation of transitional spaces and incremental spatial solutions. However, despite the relevance of Grenander’s work in the development of the mobility infrastructure in Berlin, there is a lack of systematic research data in a critical spatial analysis of the stations he designed in the interwar period and the techniques applied on the first modal stations of the city of Berlin. Therefore, this research is structured to provide historical, architectural, and theoretical-critical analyses of the design work of the Swedish architect Alfred Grenander, more concretely the subway stations for the city of Berlin, designed between 1914 and 1930. This timeframe allows to understand the transformations that affected the city urban planning and architecture for the modern period. The research assesses the formal and spatial language in the buildings' interior-exterior with the scenarios and traces left from buildings occupation. Ultimately, the aim is to analyze the transitional spaces in their capacity of transformation and ability to generate or adapt to the city urban tissue.To this end, the research project applies a case study approach on two levels. The first one is a historiographical representation – ‘light’ case studies – corresponding to a systematic documentation an overview of sixty-seven stations designed by Alfred Grenander. The second level is a more comprehensive one and corresponds to an 'in-depth' case study analysis with three morphological region-sectors that comprise a total of five stations, inserted in the city infrastructure. In line with this, the research considers typo-morphological analysis and architecture spatial analysis to develop a thesis on transitional spaces according to the urban and architectural and urban design decisions that affected the definition of the building, in a broader notion of the word ‘station’. The political decisions from the Weimar Republic period and social debates and actions give form to a conceptual basis for this analysis. Therefore, the research builds on the premises for the urban morphology methodologies developed by Conzen (1960), Cannigia and Maffei (1979) and spatial analyses by Vieira de Almeida (1968) and Colin Rowe and Robert Slutsky (1963). The epistemological framework applied to this research follows also a hermeneutic and phenomenological approach, to uncover the different meanings and perspectives from the collected data. Architecture analysis is done in a complex structure of settings from the city cultural production between individuals and its socio-historical context needed to comprehend the momentum of Berlin cultural landscape.
  

• ZHENG, QIANHUI: Planificación de la adaptación al clima extremo en el contexto del cambio climático. La ciudad esponja como elemento clave para la resiliencia
  
  Author: ZHENG, QIANHUI
  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 URBAN AND ARCHITECTURAL MANAGEMENT AND VALUATION
  Department: Department of Architectural Technology (TA)
  Mode: Article-based thesis
  Deposit date: 07/04/2025
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: ROCA CLADERA, JOSE NICASIO | ARELLANO RAMOS, BLANCA ESMARAGDA
  Thesis abstract: Climate change represents an unprecedented challenge for Mediterranean coastal regions, especially for Spain. This doctoral thesis, focused on climate change and its impact on regional extreme events, through systematic and multidimensional scientific research, reveals the complex mechanisms of climate change and its profound effects on ecosystems and urban environments.In the first part of the research, the thesis proposes an innovative method for estimating nocturnal surface temperature. By combining satellite imagery and multiple regression techniques, the study reveals significant characteristics of the urban heat island effect, especially during nighttime. This method not only improves the understanding of urban microclimate but also provides important scientific foundations for urban thermal stress response strategies.Regarding climate classification, the thesis systematically optimizes the existing climate classification system in Spain. The research introduced more geographical and climatic variables and used advanced statistical techniques, such as K-means clustering and spatial regression, significantly improving current building technical standards. The new classification method more accurately reflects the climatic diversity of Spain, providing a more detailed framework for assessing building energy efficiency.Based on high-resolution data from 1971-2022, the study systematically analyzes Spain's climate trends. The research discovered a significant warming trend, especially in maximum temperatures. Simultaneously, notable changes in precipitation patterns were observed, characterized by an overall decrease in precipitation but with an increase in the frequency and intensity of extreme precipitation events. Projections indicate that by 2050, Spain could face a crucial transition towards a semi-arid climate.In flood risk assessment, the study developed an innovative multicriteria evaluation method. Through comprehensive analysis of topographical, hydrological, and land cover factors, the research created detailed flood risk maps, with special emphasis on vulnerable Mediterranean coastal regions. Notably, the reconstruction of the significant flood event in the Valencian Community in 2024, using high-resolution precipitation data and advanced hydrodynamic models, precisely simulated the event's spatio-temporal evolution.Finally, taking the El Poblenou neighborhood in Barcelona as a case study, the thesis systematically evaluated the effectiveness of "sponge city" strategies in mitigating urban flood disasters. The study demonstrated the significant potential of technical innovations such as permeable pavements, rain gardens, and green roofs in reducing urban flood risks, providing a robust practical approach to urban climate adaptation.The research employed an innovative multi-method approach, integrating remote sensing technologies, statistical modeling, geographic information systems, and hydrodynamic analysis. The study not only expands the boundaries of climate change science but also provides scientifically feasible paths for building more resilient and sustainable urban systems.The research results highlight the urgency of implementing mitigation and adaptation measures, especially for Mediterranean coastal regions. Future research will further optimize climate models, improve flood risk assessment methods, and expand the application of "sponge city" strategies.
  

Reading date: 08/05/2025

• COLAUTTI, VIVIANA ELIZABETH: El orden desconcertado. Tensión entre soporte físico y cuadrícula. Lógicas de ocupación en la ciudad de Córdoba, Argentina.
  
  Author: COLAUTTI, VIVIANA 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 URBANISM
  Department: Department of Urbanism, Territory and Landscape (DUTP)
  Mode: Normal
  Deposit date: 10/04/2025
  Reading date: 08/05/2025
  Reading time: pending
  Reading place: pending
  Thesis director: SABATE BEL, JOAQUIN | MOISSET DE ESPANES, INES
  Thesis abstract: This research was born with the firm conviction that the growth and transformation of the city of Córdoba (Argentina) result from a unique dialogue and a complementary relationship between the physical support (that includes topography, rivers, streams, railway lines linked to contour lines) and the geometric order of the grid. These tensions develop in a very particular Latin American historical context that has shaped the city.The transformations of urban growth mainly stem from industrial-productive use (railway) and are located on the edges of natural elements (such as the Suquía river, or the La Cañada stream), or between pericentral neighborhoods. In these neighborhoods, located around its central area, the city shows very diverse grids, marked by unique physical features.The complex order of the city arises from the meeting point of three distinct orders. The abstract order of the grid, the order of the physical support and the temporal historical component. This encounter produces a disconcerting order, characterized by accelerated changes, the coexistence of heterogeneous elements and the loss of memory in undefined and interstitial areas. These areas, located next to clearly ordered areas, are the remnants of the city and cause inequalities in the use of space and strong contrasts in the urban fabric.Our main objective is to detect the occupation logic during the urban transformation processes that result from the tension between the physical support and the grid.The processes of urban growth have determined both the productive destiny of the city of Córdoba and its identity. It is the merging between a geographical dimension and a geometric one, where the growth of the grid triggers the transformation processes. This urbanization process reveals an occupation strategy that involves the transformation of the natural environment into a built environment.The concept of order, understood as an instrument of organization and an articulator between various urban components, has faced tensions all throughout the history of our Latin American cities. Such tensions derive from pre-existing elements and practices, thus shedding light on a permanent counterpoint between order and disorder. The main contribution of this thesis is to reveal the transformation processes that influenced the changes in the city. We/I seek to detect the logic behind growth and the categorization at various scales of urban interstices of the pericentral neighborhoods of Córdoba.The main hypothesis is that the order of the grid, political in origin and related to the subdivision and distribution of the land, adapts to various situations and particular intersections, while simultaneously faces the definite and physical facts of the city; in contrast to the order of the physical support, that transformsg according to the technological advances of the city and that includes the geographical, topographical, geological and structural location of the city in itself. These orders are linked by temporal historical events, giving rise to unique urban forms that reflect local logics of occupation and production, consequently emphasizing the interaction of factors and the convergence of orders that shape urban growth.We propose three methodological stages: critique, inquiry and synthesis. In the critique stage, we characterize the study area, develop questions, and define the study components (physical support and grid). In the inquiry stage, our starting point is the bibliographic and cartographic analysis of the city of Córdoba and the reading and interpretation of drawings, maps, images and data of reality and we seek to perform a process of layered reading with a certain level of abstraction. We use a set of interpretive graphics to detect permanent and emerging elements in urban transformations. In the synthesis stage, we propose a series of possible interpretation instruments.
  

• HOPMAN, JOHANNES AREND: The Checkerboard Problem in Finite Volume Methods: Origins, Solutions, and Applications in Magnetohydrodynamics
  
  Author: HOPMAN, JOHANNES AREND
  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 THERMAL ENGINEERING
  Department: Department of Heat Engines (MMT)
  Mode: Normal
  Deposit date: 10/04/2025
  Reading date: 08/05/2025
  Reading time: 11:00
  Reading place: Sala de conferències del TR5, ESIEAAT (Terrassa)
  Thesis director: RIGOLA SERRANO, JOAQUIM | TRIAS MIQUEL, FRANCESC XAVIER
  Thesis abstract: This thesis addresses the checkerboard problem in collocated Finite Volume Methods (FVM) for incompressible flows, a numerical issue caused by the decoupling of neighboring control volumes when using a collocated pressure-velocity coupling. This decoupling results in non-physical, high-frequency oscillations in the pressure field, which affect the accuracy and stability of Computational Fluid Dynamics (CFD) simulations. The research provides a mathematical analysis, a quantification method, and a numerical framework to mitigate the checkerboarding issue. The study is particularly relevant for magnetohydrodynamics (MHD) at low magnetic Reynolds numbers, where numerical stability and conservation laws are critical.The thesis is structured as follows:Chapter 1 introduces CFD and the FVM approach, the motivation for the study, and the challenges in simulating incompressible flows.Chapter 2 explores the mathematical origins of checkerboarding, highlighting how the wide-stencil Laplacian operator and mesh topology contribute to the issue.Chapter 3 introduces a checkerboard coefficient, which allows real-time quantification of the problem. A novel numerical solver is developed, balancing numerical dissipation with checkerboarding effects.Chapter 4 applies the methodology to MHD flows, incorporating a symmetry-preserving framework and testing it on electromagnetic Taylor-Green vortex and turbulent duct flow cases. The results demonstrate improved accuracy, stability, and conservation of current density.Chapter 5 presents conclusions and future research directions, including potential extensions to higher-order schemes and alternative grid arrangements.The key contributions of this work include:A mathematical understanding of checkerboarding in collocated FVM schemes.A quantification method using the checkerboard coefficient, enabling real-time monitoring.A numerical strategy that dynamically adjusts numerical dissipation to control checkerboarding.The application of these methods to MHD simulations, demonstrating their effectiveness in high-fidelity engineering applications.This research is highly relevant for applications involving complex geometries and conservation laws, such as nuclear fusion research (ITER), metallurgical processes, and electromagnetic flow control. The proposed approach enhances numerical stability while maintaining accuracy and conservation properties, laying the groundwork for future advancements in incompressible flow simulations.
  

• LAUT TURÓN, SERGI: Architecture-aware Sparse Patterns to Accelerate Inverse Preconditioning
  
  Author: LAUT TURÓN, SERGI
  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: Department of Computer Architecture (DAC)
  Mode: Normal
  Deposit date: 10/04/2025
  Reading date: 08/05/2025
  Reading time: pending
  Reading place: pending
  Thesis director: CASAS GUIX, MARC | BORRELL POL, RICARD
  Thesis abstract: This work focuses on improving the efficiency of iterative methods for solving large and sparse linear systems.These problems arise in many fields, including climate modeling, molecular and fluid dynamics, among others.To solve them, iterative methods such as the Conjugate Gradient (CG) and Generalized Minimal Residual (GMRES) methods are widely employed.Their efficiency heavily depends on the choice of preconditioners, which accelerate convergence by improving the numerical properties of the system.Sparse Approximate Inverse (SAI) preconditioners, and their factorized variant (FSAI) for symmetric positive definite systems, are particularly appealing due to their parallel-friendly nature and straightforward application via Sparse Matrix-Vector (SpMV) operations.State-of-the-art SAI and FSAI approaches define their sparsity patterns primarily based on numerical considerations.This work introduces novel architecture-aware preconditioners designed to enhance performance by optimizing the sparse pattern selection process.The first contribution presents the Factorized Sparse Approximate Inverse with Pattern Extension (FSAIE) preconditioner, an optimized version of FSAI tailored for shared memory CPU architectures.FSAIE introduces a cache-aware algorithm that extends sparsity patterns, improving both the numerical effectiveness of FSAI and its computational efficiency.Additionally, a filtering-out strategy is proposed to remove numerically insignificant entries, reducing computational cost without compromising convergence.These techniques enhance data locality in the SpMV kernel by ensuring that extended sparse patterns align with cache-line-sized memory access patterns.The second contribution extends FSAIE to distributed memory CPU environments, introducing the Communication-aware Factorized Sparse Approximate Inverse with Pattern Extension (FSAIE-Comm) preconditioner.FSAIE-Comm incorporates communication-awareness to ensure that the sparse pattern extension does not introduce unnecessary inter-process communication overhead.To prevent load imbalance, an innovative strategy is developed to distribute computational workload more evenly.The third contribution focuses on GPU execution by introducing the GPU-aware Factorized Sparse Approximate Inverse (GFSAI) preconditioner.By structuring the sparse pattern to enhance coalesced memory accesses and exploit GPU-specific architectural characteristics, GFSAI significantly accelerates FSAI computations on GPUs.The final contribution generalizes the architecture-aware preconditioning strategies beyond FSAI by introducing the Communication-aware Sparse Approximate Inverse with Pattern Extension (SAIE-Comm) preconditioner.This approach optimizes SAI for distributed memory environments, similar to FSAIE-Comm, but is adapted for general linear systems where the GMRES solver is preferable over CG.SAIE-Comm highlights the versatility and flexibility of the proposed optimizations, demonstrating that architecture- and communication-aware pattern extensions can be effectively integrated into different preconditioning strategies and solver frameworks.By integrating hardware-aware considerations into preconditioner design, this research advances the state of the art in iterative solvers and contributes to the development of scalable and high-performance numerical methods.The proposed methods achieve substantial improvements in time-to-solution across diverse High-Performance Computing (HPC) architectures, with reductions ranging from 12.94% to 26.43% on five different CPU architectures—Intel Skylake, Power9, Zen 2, A64FX, and Intel Sapphire Rapids—and from 23.83% to 26.07% on two GPU architectures—Volta and Vega20—when applied to representative sparse matrix benchmarks.These results underscore the impact of architecture-aware preconditioning strategies in modern HPC applications, paving the way for more efficient and scalable iterative solvers.