Public display of deposited theses

DOCTORAL DEGREE IN ENVIRONMENTAL ENGINEERING

• HOUCHMAND, LAURA JO: Integrated assessment of passive rooftop strategies and photovoltaic on building energy demand and urban heat island effects under current and future Mediterranean climates
  
  Author: HOUCHMAND, LAURA JO
  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 ENVIRONMENTAL ENGINEERING
  Department: Department of Civil and Environmental Engineering (DECA)
  Mode: Normal
  Deposit date: 08/04/2026
  Deposit END date: 21/04/2026
  Thesis director: GASSO DOMINGO, SANTIAGO | MACARULLA MARTÍ, MARCEL
  Thesis abstract: Climate change mitigation and adaptation are pressing challenges, particular in Mediterranean cities, where rising temperatures, intensifying urban heat island (UHI) effects, increasing cooling demand, and growing water scarcity intersect. Rooftops represent a critical interface for climate-responsive building transformation, as they offer substantial potential for passive strategies, such as cool roofs and green roofs, and active renewable technologies, particularly photovoltaic (PV) systems. Despite extensive research on rooftop technologies, four key knowledge gaps remain: (1) insufficient year-round assessment of the UHI impact of roof-mounted PV systems combined with passive roofing strategies; (2) limited integrated evaluation of green roofs and PV systems considering both building energy demand and urban climate implications; (3) lack of comparative analysis of the impact of passive roofing strategies under projected future Mediterranean climate scenarios on the buildings’ energy demand; and (4) inadequate quantification of the impacts of PV integration with passive roofing strategies on building energy demand under future climate change conditions. This doctoral research addresses these gaps through a structured, simulation-based methodological framework. The work begins with a targeted literature review to establish the scientific context of passive and active rooftop strategies in Mediterranean climates and to define the research questions. Building on these gaps, dynamic building energy simulations are conducted using DesignBuilder with EnergyPlus as the calculation engine. Barcelona (Csa climate classification) serves as the case study location. Current climate conditions are represented by high-resolution Typical Meteorological Year (TMY) data (1975–2021), while future conditions are assessed using morphed TMY files based on the IEA EBC Annex 80 methodology under RCP4.5 and RCP8.5 scenarios for mid-term (2047–2060) and long-term (2087–2100) horizons.A typical Mediterranean roof as basic roof (BR) serves as the reference case and is compared with passive strategies, including a cool roof (CR), a soil roof without vegetation (SR), and extensive green roofs under different irrigation regimes (EGR, EGRmin, EGRmax), as well as their integration with rooftop PV systems. Key performance indicators include convective heat fluxes from roof and PV surfaces (UHI contribution), conductive heat fluxes through the roof and annual heating and cooling demand (building energy demand), as well as PV electricity generation.The findings of this thesis highlight trade-offs between energy efficiency, urban heat, water use, and future climate impacts, emphasizing the need for climate-sensitive, typology-specific rooftop strategies.
  

DOCTORAL DEGREE IN MECHANICAL, FLUIDS AND AEROSPACE ENGINEERING

• BAREA SANCHEZ, GUILLEM: Wall-Bounded Supercritical Fluid Turbulence: Flow Topology & Modal Decomposition
  
  Author: BAREA SANCHEZ, GUILLEM
  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: 13/04/2026
  Deposit END date: 24/04/2026
  Thesis director: JOFRE CRUANYES, LLUÍS
  Thesis abstract: This thesis investigates high-pressure transcritical wall-bounded channel turbulence, focusing on how strong thermophysical-property variations reorganize coherent motions and multiscale flow topologies. As motivated in Chapter 1, the work analyzes Direct Numerical Simulations (DNS) of nitrogen and carbon dioxide across bulk-pressure and wall-temperature pairs that traverse the pseudo-boiling region. To ensure cross-variable and cross-case comparability in these variable-density regimes, Chapter 2 establishes the analysis toolbox and a rigorous inner-product framework utilizing Favre-weighted and compressible-energy (Chu-type) norms.The investigation begins in Chapter 3 by characterizing the multiscale flow topology using invariants of the velocity-gradient tensor. Near the hot, supercritical gas-like wall, topology distributions shift toward outer-layer–like behavior even within the viscous sublayer, marked by an elevated prevalence of vortex-sheet events. Analysis of vorticity transport links these features to baroclinic-type production driven by strong density gradients. At scales comparable to the density-gradient thickness, sheet prevalence decreases and tube-like motions become prominent, highlighting how transcritical thermodynamics reshape the structural hierarchy relative to constant-property channels.To assess energetic coherence, Chapter 4 employs Proper Orthogonal Decomposition (POD) across CO2​ cases spanning laminar to turbulent regimes. Eigenvalue spectra demonstrate that while kinetic-energy-carrying motions admit compact representations, thermodynamic fields (temperature and specific isobaric heat capacity) are characterized by stronger intermittency and localization, requiring higher-dimensional subspaces. Cross-variable analyses reveal pronounced co-organization of hydrodynamic and thermodynamic modes inside pseudo-boiling layers, necessitating multi-variable states for accurate reduced-order descriptions.In the frequency domain, Spectral Proper Orthogonal Decomposition (SPOD) is utilized in Chapter 5 to reveal a coherent-structure scaffold for transcritical turbulence. A robust low-frequency band (f^​≈0.27) persists across operating conditions, manifesting as a wall-attached, streamwise-elongated sheet. Distinct from this universal hydrodynamic feature, a higher-frequency thermal branch appears conditionally at near-critical pressures and large wall-temperature differences, exhibiting compact structures and enhanced thermodynamic activity.Finally, the implications of these findings for modeling are synthesized in Chapter 6. The evidence supports Reduced Order Model (ROM) strategies that integrate thermodynamic variables into the state vector and respect the identified spectral separation. The thesis concludes by outlining pathways for integrating operator-based resolvent analyses with data-driven modes to develop physics-consistent ROMs for high-pressure real-fluid systems.
  

DOCTORAL DEGREE IN SIGNAL THEORY AND COMMUNICATIONS

• MOSAHEBFARD, MOHAMMADREZA: Resource Management in Sliced Converged Optical-Wireless 6G Networks: From Strategic Dimensioning to Dynamic Service Provisioning
  
  Author: MOSAHEBFARD, MOHAMMADREZA
  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: 10/04/2026
  Deposit END date: 23/04/2026
  Thesis director: VERIKOUKIS, CHRISTOS | VARDAKAS, JOHN
  Thesis abstract: The evolution toward the 6th Generation (6G) networks relies on converged optical-wireless infrastructures and virtualization technologies like Network Functions Virtualization (NFV) to support diverse services through Network Slicing. While enabling flexibility, these paradigms introduce profound complexity in managing shared computational and com-municational resources. This thesis addresses this challenge by identifying a fundamental temporal duality in resource management, spanning the strategic need for agile capacity planning to the operational necessity of real-time service provisioning. This complexity is further aggravated by the presence of various network slices, each with distinct Quality of Service (QoS) requirements. To resolve this dichotomy, distinct methodologies are developed within this PhD thesis.To address the strategic domain, where Mobile Virtual Network Operators (MVNOs) require rapid dimensioning tools for flexible resource leasing, this PhD thesis develops a computationally efficient analytical framework based on one-dimensional Markov chains. Uniquely, this model captures resource occupancy at two levels: physical resources governing Service Function Chain (SFC) instantiation, and virtual resources governing user admission. This stratified modeling avoids state-space explosion while accurately calculating admission ratios, achieving relative errors typically below 2% compared to simulations. The framework is applied to determine the minimum resources required to achieve target admission ratios under varying arrival rates, as well as to identify the necessary capacity to meet different target admission rates under constant traffic loads. This capability enables rapid offline dimensioning to guarantee Quality of Service (QoS) thresholds, offering a scalable alternative to time-consuming simulations and resource-exhaustive optimization approaches.Complementing this, the operational challenge of online SFC Embedding (SFCE) is addressed. Recognizing the NP-hardness of the embedding problem with the objective of jointly minimizing holistic power consumption and blocking probability, HORIZON, a novel holistic heuristic designed to optimize Mobile Virtual Network Operator (MVNO) operational efficiency, is developed. It employs a proactive backward placement strategy coupled with power and latency-aware segmental routing, and integrates comprehensive power models for both servers and Reconfigurable Optical Add-Drop Multiplexers (ROADMs). By enforcing strict inter-slice isolation while maximizing intra-slice efficiency, HORIZON achieves power efficiency within 15% of optimal Integer Linear Programming (ILP) bounds under resource-constrained scenarios. Evaluations across four realistic network topologies demonstrate execution times of 10–18 ms per service request (38–67 times faster than optimal solvers), power savings up to 23.6% compared to state-of-the-art heuristics, and negligible blocking rates, enabling MVNOs to minimize OPerational EXpenditure (OPEX) while strictly adhering to Service Level Agreements (SLAs).
  

DOCTORAL DEGREE IN SUSTAINABILITY

• LARVOE, NOAH: FROM FARM TO FORK: THE ROLE OF FARMERS AND CONSUMERS IN PESTICIDE REDUCTION IN EUROPEAN VINEYARDS AND OLIVE GROVES
  
  Author: LARVOE, NOAH
  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 SUSTAINABILITY
  Department: University Research Institute for Sustainability Science and Technology (IS.UPC)
  Mode: Article-based thesis
  Deposit date: 10/04/2026
  Deposit END date: 23/04/2026
  Thesis director: KALLAS CALOT, ZEIN
  Thesis abstract: Sustainability transitions in agri-food systems require coordinated adjustments on both the supply and demand sides of food value chains. In the Mediterranean wine and olive sectors, in which chemical pesticides remain central to pest and disease control, reducing pesticide use in line with the European Union objective of halving synthetic pesticide use by 2030 depends on both consumer support for reduced pesticide products and farmers’ willingness to adopt innovations that make such reductions feasible. This thesis examines whether and under what conditions market demand and farmer behaviour can support pesticide reduction in Mediterranean orchard systems through four empirical studies.The first study analyses consumer preferences for extra virgin olive oil with reduced pesticide use using a reference-dependent contingent valuation survey of 5,091 consumers in France, Greece, Italy, Portugal, and Spain. Approximately 73% of respondents are willing to pay a premium for olive oil produced with a 40% reduction in pesticide use. The estimated mean premiums range from 22% in Italy to 26% in France relative to products produced under standard practices. The second study examines organic wine consumers to estimate the proportion of the organic price premium attributable to the non-use of synthetic pesticides. It employs a reference price-dependent discrete choice experiment (DCE) with 1,070 consumers. The results show that the non-use of synthetic pesticides accounts for 74% of the average reference organic price reported in the study, exceeding the contribution of other organic attributes, while the EU-approved third-party certification generates the highest positive effect. Latent class analysis identifies three consumer segments, namely, awareness-driven, certification-driven, and price-sensitive consumers, which differ systematically in attitudes, knowledge, and purchasing experience. The third study extends the analysis to the conventional wine market using a dynamic reference-dependent DCE with 4,000 consumers in the same countries. The results show that wines produced with a 40% reduction in pesticide use command significant price premiums, ranging from approximately 26% in France to 30% in Italy and Portugal. Consumers’ environmental attitudes, past purchasing prices, and subjective knowledge significantly influence their preferences, although the strength of these effects varies across countries. The fourth study examines farmers’ intentions to adopt pesticide-reducing innovations using data from 16 expert interviews and a structured survey of 354 orchard farmers within an extended theory of planned behaviour framework. Adoption intentions are driven by positive attitudes toward pesticide reduction and favourable perceptions of ease of use, while perceived costs and beliefs in the superior performance of existing practices constitute significant barriers. Subjective norms and perceived behavioural control do not predict adoption intentions. These findings are used to develop a predictive tool that determines the likelihood of a farmer adopting pesticide-reducing innovations. Overall, the findings suggest that consumers can provide economically meaningful incentives for pesticide reduction in viticulture and olive groves, while farmers’ adoption decisions are shaped mainly by attitudes, perceived complexity, and economic considerations. Policy and stakeholder strategies that combine credible certification, targeted information, and support for innovation costs are likely to strengthen the alignment between market demand and farm-level decision-making. This thesis provides an economic and behavioural assessment of how consumers and farmers can contribute to the EU’s Green Deal objective of reducing pesticide use. Further, it outlines priorities for future research, notably market trials, longitudinal studies of farmer adoption behaviour, and integrated assessments of economic and environmental impacts of pesticide reduction