Doctoral School

Reading date: 13/09/2024

• KOSTALAMPROS, IOANNIS - VATISTAS: Post-quantum cryptography acceleration for next generation computers
  
  Author: KOSTALAMPROS, IOANNIS - VATISTAS
  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: 14/06/2024
  Reading date: 13/09/2024
  Reading time: 10:30
  Reading place: Sala E101 - Edifici C6 (FIB) - Campus Nord - Barcelona
  Thesis director: MORETÓ PLANAS, MIQUEL | HERNANDEZ LUZ, CARLES
  Committee:
       PRESIDENT: CANO REYES, JOSE
       SECRETARI: MARTORELL BOFILL, XAVIER
       VOCAL: TSOUTSOURAS, VASILIOS
  Thesis abstract: The security of modern cryptographic schemes relies upon mathematical problems that are assumed to be hard to solve, like the Rivest-Shamir-Adleman (RSA) problem or the discrete logarithm problem over elliptic curves. Using the existing “classical” computers, all known algorithms attempting to solve these problems, would require such a big amount of computational time that will actually make the intercepted data useless by the time the attack finishes.Around 1997, Shor and Grover independently developed efficient quantum-computer algorithms that can give unprecedented speedup on certain mathematical problems. It then became evident that the advent of a large scale quantum computer can jeopardize secure communications. Nevertheless, it is still not clear whether there will exist large scale quantum computers able to break the current public key cryptographic standards. As a preemptive act, the National Institute of Standards and Technology (NIST) announced in 2015 its plans for transitioning to Post-Quantum (PQ) cryptographic algorithmic standards. The widespread adoption of the current standards , calls for further research on the efficiency and security of the PQ standards implementation on modern computing systems.This thesis intends to bridge the gap between the PQ cryptosystems’secure specification and their respectively secure and efficient implementation in advanced computing architectures.We specifically choose the PQ cryptosystem of Classic McEliece (CM), merely due to its long-standing security. CM has withstood attacks with minor modifications since its inception in 1978 and is currently a finalist of the NIST contest and has already been integrated in commercial products like VPN networks.This thesis comprises four main contributions. In the first one we present a hardware/software (HW/SW) co-design acceleration of the CM cryptosystem. The second contribution is geared towards the design and integration of custom designed and monolithic CM accelerators in a RISC-V based SoC. The third contribution strives to further optimize the performance of CM in hardware by introducing an advanced design of a monolithic accelerator for the encryption part of the CM cryptosystem. The final contribution of this thesis is moving away from a monolithic hardware accelerator and investigates the impact of vectorization by an SIMD unit on the CM application.With this thesis, we conclude a study conveyed on the CM cryptosystem, concerning its efficient hardware implementation on modern computing infrastructures. Nevertheless, there are numerous future research directions that could build on the knowledge gained as well as the hardware infrastructure designed in the context of this thesis. As such, we consider the secure implementation and side-channel mitigation on the CM hardware accelerators themselves and the performance evaluation of lightweight hardware implementations of CM.
  

Reading date: 16/09/2024

• BUITRAGO LEIVA, JEIMMY NATALY: Contributions to Eco-Friendly Satellite Lean Design for a Sustainable Space Environment
  
  Author: BUITRAGO LEIVA, JEIMMY NATALY
  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 AEROSPACE SCIENCE AND TECHNOLOGY
  Department: Department of Physics (FIS)
  Mode: Normal
  Deposit date: 10/07/2024
  Reading date: 16/09/2024
  Reading time: 15:00
  Reading place: Sala de juntes. Edifici D4
  Thesis director: CAMPS CARMONA, ADRIANO JOSE
  Committee:
       PRESIDENT: ALIAKBARGOLKAR, ALESSANDRO
       SECRETARI: GUTIERREZ CABELLO, JORGE LUIS
       VOCAL: ULLOA SANDE, CARLOS
  Thesis abstract: Currently, half of the satellites do not reach 20% of their expected lifetime. The possibility of recycling these "zombie satellites" (ZS) with limited capabilities would optimize this on-orbit infrastructure, reducing unnecessary launches and being more cost-effective. A 12U CubeSat costs around €2.5 million to manufacture and launch. In this way, there would be no need to launch new satellites for new missions, resulting in positive environmental and economic impacts. This research proposes an ecological approach to satellite design and operation, integrating space sustainability strategies and green practices within the NewSpace paradigm. For a comprehensive analysis of the satellite lifecycle, eco-friendly and lean manufacturing characteristics need to be integrated. This concept aims to consolidate efforts towards a sustainable space and considers innovative technologies for standard satellites.This doctoral thesis undertakes a research study and practical experiences focused on small satellites, divided into 6 parts with 12 chapters.The first part, with two chapters, introduces space sustainability and the Eco-LeanSat concept, emphasizing a sustainable approach to satellite manufacturing and the reuse of capabilities after failure. It addresses the evolution of smallsat capabilities and institutional efforts to promote sustainability strategies.The second part, comprising two chapters, deals with proposals for reusing satellites that have failed in orbit. Chapter three analyzes the most common failures in smallsats and proposes mission design to reuse these capabilities and prevent them from becoming space debris. Chapter four studies the causes of failures arising from the space environment.The third part proposes agile methodologies, Lean Six Sigma, and Model-Based System Engineering (MBSE) software for satellite manufacturing, applied to NanoSat Lab missions: 3Cat-4 and 3Cat-8, and the Colombian mission 3ColStar. Chapter five applies Lean Six Sigma to the 3Cat-8 mission, identifying bottlenecks and optimizing execution. Chapter six presents the preliminary design of the 3ColStar mission, incorporating MBSE software. Chapter seven develops algorithms for the Attitude Control System in the 3Cat-8 mission. Chapter eight performs thermal analysis of the 3Cat-4 mission.The fourth part, with chapter nine, addresses legal considerations for future sustainable missions, highlighting the lack of specific regulations for satellite reuse in orbit. Chapter ten proposes future studies with a sustainability focus.The fifth part includes appendices of the mentioned chapters, and the sixth part lists publications and other academic activities conducted during the doctoral study
  

• CUNQUERO NAVARRO, MARINA: Use of Advanced Imaging Tools for Assessing the Performance of Novel Therapeutic Techniques for Restoring Vision
  
  Author: CUNQUERO NAVARRO, MARINA
  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 PHOTONICS
  Department: Institute of Photonic Sciences (ICFO)
  Mode: Normal
  Deposit date: 18/07/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: LOZA ALVAREZ, PABLO | MARSAL TERÉS, MARIA
  Committee:
       PRESIDENT: PICAUD, SERGE
       SECRETARI: KRIEG, MICHAEL
       VOCAL: ACCANTO, NICOLO
  Thesis abstract: Studying vision restoration is paramount for addressing degenerative blinding diseases, which significantly impact quality of life and public health. With more than 230M people worldwide affected by moderate to severe vision loss, and an estimated increase in blindness from 38M to 115M by 2050, the urgency for effective treatments is clear. Vision, being the most complex and crucial human sense, relies on an intricate network of structures. Light is captured by photoreceptors in the retina and translated into neural signals processed by the brain, enabling sight. Degenerative diseases often involve the progressive deterioration of photoreceptors, leading to blindness. Currently, there is no cure but various approaches are being researched to restore sight. These include gene and cell therapies targeting diseased tissue, as well as methods like optogenetics and neuroprosthetics to modulate neuron activity and bypass dysfunction. By understanding and manipulating neural activity, scientists aim to restore vision or slow down the degenerative processes.The results of this PhD thesis highlight progress across four areas for vision restoration research. Chapter 2a explores a new retinal implant using biocompatible reduced graphene oxide microelectrodes, demonstrating its ability to record neural signals from retinal tissue and capture light-induced firing patterns in retinal ganglion cells. It also details a protocol for retinal calcium imaging, facilitating future studies combining electrical stimulation with optical techniques. Chapter 2b focuses on adapting an ophthalmoscope for in vivo, single-cell resolution imaging of the retina in rodents, aiming to set the basis for future implementations to monitor the functionality of implanted retinal prostheses. Chapter 3 delves into the potential of human-induced pluripotent stem cell-derived retinal organoids for vision research. Using advanced imaging techniques, researchers successfully observed the formation of distinct retinal cell types within the organoids and identified differences in calcium dynamics between healthy and diseased models. Future work aims to refine MEA recordings and investigate the link between retinal organoid structure and function. Chapter 4 introduces a novel three-photon excitation technique offering deeper brain penetration and higher precision compared to traditional methods. This approach successfully regulates neuronal activity in zebrafish with minimal light exposure, showcasing its potential for revolutionizing the study of neural circuits and development of neuromodulation therapies.Taken together, these advancements across retinal implant design, in vivo monitoring of the retina, studying the potential of patient-derived organoid models, and development of non-invasive three-photon brain stimulation techniques, pave the way for future development of more effective vision restoration therapies.
  

• HUANG, DAWEI: Influence of interfacial bonding behavior on the compressive performance of sprayed mortar reinforced masonry walls
  
  Author: HUANG, DAWEI
  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, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY
  Department: Department of Architectural Technology (TA)
  Mode: Article-based thesis
  Deposit date: 18/07/2024
  Reading date: pending
  Reading time: pending
  Reading place: pending
  Thesis director: ALBAREDA VALLS, ALBERT | PONS VALLADARES, ORIOL
  Committee:
       PRESIDENT: ÜSTÜNDAG, CENK
       SECRETARI: CORNADÓ BARDÓN, CÒSSIMA
       VOCAL NO PRESENCIAL: LIU, PENG
  Thesis abstract: This thesis investigates the adhesion behavior between sprayed mortar and masonry substrates, focusing on the influence of compressive strength, mortar age, and surface roughness on adhesion strength. Through detailed experiments and comprehensive analysis, it seeks to better understand these factors and their impact on rehabilitation techniques for masonry structures. The results of this investigation not only expand theoretical knowledge about the adhesion behavior between mortar and masonry but also provide practical recommendations to improve the durability and effectiveness of retrofitting interventions.Experiments were conducted on samples with different compressive strengths (15 MPa, 30 MPa, and 45 MPa) to assess how these factors affect both tensile and shear adhesion strength. It was observed that the tensile adhesion strength decreases with increasing compressive strength of the masonry due to the brittle nature of high-strength materials. Specifically, masonry with a compressive strength of 15 MPa showed tensile adhesion strength ranging from 0.2 to 1 MPa, while masonry with a compressive strength of 40 MPa showed values concentrated between 0 and 0.1 MPa. This behavior is due to the fact that high-strength masonry tends to fail more abruptly, reducing its capacity to maintain adhesions under tension.On the other hand, the shear adhesion strength showed a positive correlation with compressive strength. Substrates with higher compressive strength provided greater shear capacity due to better mechanical interlocking facilitated by surface roughness. Experimental results demonstrated that the shear adhesion strength was almost double that of the tensile strength, highlighting the importance of surface texture in adhesion performance.The age of the mortar is also a crucial factor. Tests were conducted at 7 and 28 days to evaluate the development of adhesion strength over time. At 7 days, the adhesion strength was relatively low due to the ongoing hydration process and incomplete development of the mortar's mechanical properties. However, at 28 days, the adhesion strength increased significantly as the mortar achieved higher levels of hydration and improved mechanical properties. This underscores the importance of allowing adequate curing time in practical applications to ensure the longevity and effectiveness of reinforced structures.Surface roughness is a determining factor in adhesion strength. We measured roughness using the Joint Roughness Coefficient (JRC) and the arithmetic mean deviation (Ra) to quantify its impact. It was found that rougher surfaces facilitated better mechanical interlocking, improving adhesion strength. This finding highlights the importance of surface preparation in rehabilitation applications, where increasing the substrate's roughness can significantly enhance adhesion performance.The experiments revealed three typical modes of failure: adhesion disconnection, specimen fracture, and adhesion material fracture. Adhesion disconnection occurred when the adhesion strength was weaker than the individual strengths of the mortar and masonry, resulting in a clean separation at the interface without significant damage. Specimen fracture was mainly observed in samples with a fragile surface layer developed during mortar curing. Adhesion material fracture involved the rupture of the adhesion material itself, highlighting the impact of shear stress on adhesion integrity.
  

• SOLA FONT, JOAN: Hipòtesis sobre una línia. Nuclis urbans i estacions a les línies interiors catalanes.
  
  Author: SOLA FONT, JOAN
  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: 15/07/2024
  Reading date: 16/09/2024
  Reading time: 11:30
  Reading place: Defensa pública Presencial (ETSAB. Planta Baixa. Sala de Graus)
  Thesis director: EIZAGUIRRE GARAITAGOITIA, FRANCISCO JAVIER | CROSAS ARMENGOL, CARLES
  Committee:
       PRESIDENT: RUBERT DE VENTOS, MARIA
       SECRETARI: MARTI CASANOVAS, MIQUEL
       VOCAL: SARDÀ FERRAN, JORDI
       VOCAL: GÓMEZ ORDOÑEZ, JOSÉ LUIS
       VOCAL: GARCIA FONTAN, CRISTINA
  Thesis abstract: "Hypothesis on a Line" analyses the impact that the construction of the railway has had on the urban centres along the interior lines of the Catalan network. The integration of a territorial mobility infrastructure into these fragile territories, with their seemingly modest urban heritage, has exerted a prolonged and significant influence from its inception to the present day.In the first part, the thesis focuses on the line from Granollers to Sant Joan de les Abadesses (GRN-SJA) and on eight of the urban centres it connects. This mining railway project, designed by Ildefons Cerdà, highlights the overlap of its ideological and theoretical foundation with its actual construction. Although initially projected for the extraction of coal in Ogassa, the arrival of the train had a significant impact on the towns, paradigmatically reflected in the urban morphology of each of the eight analysed localities. In the second part, the research extends the observation of the railway's impact to a selection of forty-four urban realities in various territories of the Catalan interior railway network.The thesis shows how the reaction of each urban centre is complementary, and sometimes contradictory to its own urban evolution. This evolution shifts from the initial optimism and confidence in progress generated by the railway, through its obsolescence as a communication system, to its current potential as a sustainable means of transport. The introduction of the railway as an external element with strong infrastructural conditions initially creates an urban tension with the station building, influenced by the physical distance and its symbolic value within the context of these towns. This situation brings about a first generation of urban elements: the station square, the station street, and the station neighbourhood. Subsequently, another set of elements will emerge, forming the 'other side' of the track, with facilities of wider territorial scope that contribute to enriching the syntax of contemporary railway urbanity.The set of urban reactions faces the geometric heritage of the railway with the traditional suburban nature of the surrounding urban fabrics. Thus, the local differences of each urban reality are linked by a territorial similarity that makes them common and comparable as part of the same line. The elements constructed over more than a century around this infrastructure display varying degrees of identity, transformation, and opportunity, acquiring greater complexity when viewed from the perspective of the entire railway space. The fragmentary urbanity of the railway invites to reflect on the different degrees of urban belonging and the hypothetical intensification of uses around the station and, by extension, throughout the entire railway urban space.Historically, the railway infrastructure has become an 'implant' that, in some cases, coexists with the urban fabric without generating significant effects around it. In other cases, it has created urban links or 'grafts' in its surroundings. Additionally, the continuity of the railway edges and their transversal capillarity with the nearby urban fabrics define an intermediate space with notable potential for transformation and improvement.Finally, the thesis seeks to demonstrate the ongoing relevance of the accumulated railway urbanity in some of the urban centres it connects, and its potential beyond the station area. From a trans-scalar perspective, it aims to highlight the Catalan interior railway lines as a heritage to be preserved and enhanced in the future.