97828 research outputs found
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Depth Error and Noise Analysis in Multi-frequency Indirect Time-of-Flight Imaging
No full textCompendi d'articles, Doctorat industrialThis PhD thesis investigates the fundamental limitations and performance factors of indirect Time-of-Flight (iToF) camera systems, with a focus on improving phase estimation accuracy and depth reliability. The global objective is to enhance the understanding of error sources in iToF systems and to develop models and methodologies that improve their robustness and precision in both academic and industrial contexts. The research is structured around three main contributions. First, a multi-objective optimization framework is proposed for selecting modulation frequencies in multi-frequency iToF systems. This model simultaneously minimizes phase unwrapping errors and maximizes depth precision, while incorporating constraints such as maximum unambiguous range and frequency limits, adapting to specific application requirements. Thanks to this multi-objective formulation, the proposed optimization model improves the performance over existing methods. Second, the thesis presents a generalized shot noise model for traditional sampling architectures. This model accounts for key system parameters including modulation frequency, signal amplitude, background illumination, integration time and the number of points in the Discrete Fourier Transform. It provides a deeper understanding of noise behaviour. A second order-order error propagation is modelled to get a more accurate phase variance estimation. Third, the analysis is extended to the differential sampling architecture used in commercial sensors, such as those developed by Analog Devices Inc (ADI). This architecture simplifies the analog front-end and removes the DC component of the received light, optimizing the use of the dynamic range of the Analog to Digital Converter. A new shot noise model is derived, showing that phase error is inversely proportional to signal amplitude and directly proportional to background illumination, while remaining independent of the number of points in the Discrete Fourier Transform. Together, these contributions form a unified framework that links frequency design and noise modelling, offering practical tools for optimizing iToF systems. The proposed methodologies have been validated through extensive simulations and experimental data, and have been integrated into the development of next-generation iToF modules at ADI. This work lays the foundation for future research in adaptive frequency selection strategies and enhanced noise mitigation, particularly in environments affected by multipath interference and dynamic scene conditions.Programa de Doctorat en Informàtic
Configuraciones críticas de las (in)seguridades y la violencia en Colombia después de la firma del Acuerdo de Paz con las FARC-EP: transeguridad y tiempo para la paz transicional
No full textLa terminación del conflicto entre el Estado colombiano y las FARC-EP abrió nuevos escenarios de inseguridad y violencia, manteniendo la paz como un asunto intangible e inconcluso. Esta tesis doctoral propone un marco analítico innovador para comprender estas dinámicas y plantear rutas hacia una gobernanza para la paz. Con una metodología ecléctica, se desarrollan conceptos originales sobre la relación entre violencia, crimen, inseguridad y paz. La investigación se guía por la pregunta: ¿cómo se configuran los estadios de la seguridad y la violencia en Colombia tras el Acuerdo de Paz (2017-2022)? Los hallazgos incluyen los conceptos de polipaces, seguridad transicional, transeguridad y paz transicional, útiles para explicar la complejidad del posconflicto. Como conclusión, se formulan propuestas de gobernanza para la paz orientadas a la inclusión territorial, la cohesión social y la desviolentización del país.The end of the armed conflict between the Colombian State and the FARC-EP opened new scenarios of insecurity and violence, leaving peace as an intangible and unfinished endeavor. This doctoral thesis proposes an innovative analytical framework to understand these dynamics and to outline pathways toward governance for peace. Using an eclectic methodology, it develops original concepts on the relationship between violence, crime, insecurity, and peace. The research is guided by the question: How are the stages of security and violence configured in Colombia after the Peace Agreement (2017–2022)? The findings introduce the concepts of polypeaces, transitional security, transecurity, and transitional peace, which contribute to explaining the complexity of the post-conflict context. In conclusion, the thesis formulates proposals for peace governance aimed at fostering territorial inclusion, social cohesion, and the de-violentization of the country.Programa de Doctorat en Estudis Internacionals de Pau, Conflictes i Desenvolupamen
Influence of vehicle–track–bridge–soil interaction on the dynamic behaviour of railway bridges for accurate prediction of their vibratory response
No full textCompendi d'articles, Doctorat internacionalRailway transport has experienced a sustained development in recent decades characterised by increases in the travelling speed and the operating capacity of many railway lines. As these conditions are also expected in the long-term, they pose a significant challenge for the infrastructure, as it will have to withstand more demanding conditions. Thus, a thorough understanding of the train-induced vibration problem in railway bridges is key to ensuring the required levels of quality, safety and reliability in these critical structures. However, their dynamic behaviour is complex and is affected by multiple factors, among which the vehicle–track–bridge–soil interaction is particularly important. For this reason, the main objective of this thesis is to investigate its influence on the dynamic response of railway bridges with the aim of providing deeper insight into the phenomena involved and to achieve more accurate predictions of the bridge performance under operating conditions.Programa de Doctorat en Tecnologies Industrials i Material
Improving heat-to-electricity energy conversion with thermoelectric materials by means of electrochemical strategies
No full textCompendi d'articlesApproximately 72% of global energy consumption is lost in the form of waste heat. Thermoelectric (TE) devices have gained significant attention owing to their potential to transform heat into electricity, thus contributing to mitigate the present energy crisis. The TE performance is evaluated by the figure of merit zT=S2σT/κ, where S denotes the Seebeck coefficient, σ is the electrical conductivity, T represents the absolute temperature, and κ refers the thermal conductivity. Therefore, obtaining a high zT requires a large power factor (PF=S2σ) together with low κ. This thesis explores the enhancement of the PF in PEDOT:PSS, Ag-ZnO composite, bismuth/antimony telluride alloys, and Sb-doped SnO2 through electrochemical strategies. Upon treatment with 4,4'-bipyridine or LiBF4, PEDOT:PSS exhibited over 3 times PF enhancements. Ag-ZnO combined with BMII ionic liquid resulted in a 1.5-fold increase in the PF. Sb-doped SnO2 functionalized with redox molecules produced 2.5-fold PF improvements.Programa de Doctorat en Tecnologies Industrials i Material
La integración de la alfabetización mediática e informacional en el currículum educativo de la Comunitat Valenciana: un análisis de contenido
No full textEn una sociedad cada vez más digitalizada y con amplio acceso a la información, la alfa-betización mediática e informacional (AMI) ha adquirido una relevancia especial en el ámbito educativo. Con la implementación de la LOMLOE y su concreción autonómica, este estudio analiza el grado de integración de la AMI en los currículos de la Comunidad Valenciana. Para ello se ha llevado a cabo un análisis documental de los tres decretos que establecen los currículos de las etapas de Educación Infantil, Primaria y Secundaria Obli-gatoria. Los resultados muestran que las competencias vinculadas a la evaluación crítica de la información y el uso adecuado de formatos diversos son las más destacadas en todas las etapas (áreas AMI 4 y 5). Sin embargo, se observa una presencia limitada de conteni-dos que promuevan activamente la AMI entre estudiantes y ciudadanía, o que profundi-cen en la comprensión de los medios y la comunicación. En cuanto a Educación Secun-daria, esta etapa sobresale con una integración más elevada de las competencias AMI, respondiendo a la necesidad de preparar a los jóvenes para afrontar los desafíos mediáticos actuales. Este estudio ofrece una visión crítica de la aplicación de la AMI en la educación autonómica y establece las bases para reforzar la formación mediática y crítica de una ciudadanía informada.In an increasingly digitalised society with broad access to information, the importance of media and information literacy (MIL) in the educational field has particularly increased. With the enactment of the Organic Law Amending the Organic Law of Education (LOMLOE) and its regional implementation, this study analyses the level of MIL integra-tion in the curricula of the Valencian Community. A documentary analysis of the three Acts establishing the curricula for Early Childhood, Primary, and Secondary Education was carried out. The results show that competencies relating to critical evaluation of infor-mation and appropriate use of diverse formats are the most prominent at all educational stages (AMI areas 4 and 5). However, there is a limited presence of content that actively promotes MIL among students and citizens or deepens understanding of media and com-munication. Secondary education has higher levels of integration of MIL competencies, addressing the need to prepare young people to face current media challenges. This study offers a critical perspective on the application of MIL in regional education and lays the foundation for strengthening media literacy and critical skills to foster an informed and critical citizenry
Flexible combined latent heat and cold storage for dual thermal output with large temperature difference
No full textThe industrial sector confronts the dual imperatives of escalating thermal energy demands and urgent decarbonization objectives. Addressing the critical challenge of simultaneously delivering heating and cooling across large temperature differences (ΔT ≥ 100 °C) in multi-thermal-regime industrial processes, conventional approaches often rely on separate systems and lack demand-responsive capabilities. This experimental study presents a combined heat and cold storage (CHCS) system integrating a cascade heat pump with a latent heat storage unit (PCM90) and a 0 °C ice storage unit on both heating and cooling sides, respectively, through a series-parallel configuration. Four operational modes are developed: baseline charging (CHG) and discharging (DCHG), and flexible dual energy consumer (DEC) and supplier (DES) modes. These modes dynamically couple and decouple components to align with time-variable electricity tariffs while optimizing adaptability. System performance is evaluated through the process-specific and cycle-level coefficient of energy utilization ( and ). Experimental results demonstrate a maximum of 3.15 across complete storage-supply cycles, with baseline charging achieving a peak of 3.24. In DEC mode, the system sustains concurrent heating and cooling loads during phase transitions, while DES mode extends heat supply durations by 32.0–42.0 % and cold supply durations by 22.8–56.2 % through auxiliary thermal supplementation of the heat pump. Collectively, this work establishes a scalable paradigm of simultaneous heating and cooling production and combined heat and cold storage for industrial decarbonization, positioning CHCS as a cornerstone technology for harmonizing large temperature lift thermal delivery
Stimuli-Responsive NHC-based Pincer Complexes for Catalysis
No full textCompendi d'articles, Doctorat internacionalThis Doctoral Thesis demonstrates the potential of supramolecular and anion‑induced redox interactions as effective tools to endow transition metal pincer complexes with adaptive and reversible control over their electronic properties, and consequently over their catalytic behaviour. Systematic studies on Rh(I), Mn(I), and Pd(II) platforms revealed that these interactions can independently modulate the electronic structure and reactivity in a controlled and reversible manner. The incorporation of the NDI moiety transforms the pincer ligand into a multistimuli-responsive unit that mediates communication between external additives—such as halides and polycyclic aromatic hydrocarbons—and the electronic state of the metal centre. This strategy moves beyond static ligand design and introduces a dynamic approach to catalyst tuning, enabling reversible switching between distinct activity states using mild and easily accessible stimuli. Overall, the study highlights supramolecular and redox-active ligand frameworks as versatile platforms for developing next-generation stimulus-responsive catalysts.Programa de Doctorat en Cièncie
Comparative Insights: Fuzzy Clustering Versus Archetypal Analysis in Vector Quantisation for Blosc2
No full textBlosc2 is a high-performance compression library and data format designed for binary data such as numerical arrays, tensors, and other structured types. In this proposal, we aim to develop two new codecs for Blosc2 by leveraging its extensible plugin- based codec framework. Specifically, we propose integrating archetypal analysis (AA) and fuzzy clustering as novel codecs within Blosc2. Our proposal has been assessed by using the Olivetti faces dataset and results have demonstrated that AA outperforms fuzzy clustering in preserving fine-grained data details, achieving substantially higher Structural Similarity Index. These results underscore AA’s capability to capture the complete data distribution, including its extreme values, which is an essential property for achieving high-fidelity compression.Funding for open access charge: CRUE-Universitat Jaume
Microwave-Assisted Synthesis of CsPbBr3 Perovskite Nanocrystals for Optoelectronic Applications Resum de la tesi (Anglès)
No full textCompendi d'articles, Doctorat internacionalPerovskite nanocrystals have emerged as outstanding materials for optoelectronic applications due to their tunable composition, bright emission, and tolerance to defects. Among them, all-inorganic CsPbBr3 nanocrystals exhibit exceptional photoluminescence and stability, making them ideal for next-generation LEDs. However, conventional hot-injection synthesis is complex, energy-intensive, and unsuitable for scale-up. This Ph.D. thesis explores microwave-assisted synthesis as a fast, sustainable alternative, enabling precise control of crystal size and halide composition while achieving high photoluminescence quantum yields after purification. The resulting nanocrystals were successfully integrated into LEDs, showing sharp emission, high efficiency, and excellent luminance. A life cycle assessment revealed that microwave synthesis dramatically reduces energy consumption compared to conventional methods, without compromising material quality. Overall, this work demonstrates that microwave-assisted strategies combine performance and sustainability, offering a scalable route for high-quality CsPbBr3 nanocrystals and advancing their integration into practical optoelectronic technologies.Programa de Doctorat en Cièncie
Laser-synthesized fluorescent carbon quantum dots (CQDs) in liquids: harnessing their potential for biomedical applications
No full textDoctorat internacionalCarbon quantum dots (CQDs) have attracted significant interest for biological, catalytic, and energy applications due to their tunable fluorescence and unique physicochemical properties. Laser-based synthesis in liquids, particularly pulsed laser fragmentation in liquids (PLFL), offers an eco-friendly, scalable, and high-purity method for CQD production, though their practical biomedical applications remain underexplored. This work investigates PLFL-synthesized CQDs and demonstrates their functionality in sensing and drug delivery. CQDs were functionalized with aminophenylboronic acid to create a fluorescence-based, non-enzymatic glucose sensor exhibiting high photostability, a quantum yield of 35%, good selectivity, and a detection limit of 165 μM, with successful performance in saliva samples. Additionally, CQDs were incorporated into biocompatible polymeric nanoparticles for sorafenib delivery, enabling fluorescence tracking, enhanced anticancer efficacy, and strong anti-angiogenic effects in vitro and in vivo. Overall, PLFL-synthesized CQDs show strong promise as multifunctional platforms for biomedical sensing and drug delivery.Programa de Doctorat en Cièncie