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The optical and photovoltaic properties of Si NCs / SiC multilayers (MLs) are investigated using a membrane-based solar cell structure. By removing the Si substrate in the active cell area, the MLs are studied without any bulk Si substrate contribution. The occurrence is confirmed by scanning electron microscopy and light-beam induced current mapping . Optical characterization combined with simulations allows us to determine the absorption within the ML absorber layer, isolated from the other cell stack layers. The results indicate that the absorption at wavelengths longer than 800 nm is only due to the SiC matrix. The measured short-circuit current is significantly lower than that theoretically obtained from absorption within the ML absorber, which is ascribed to losses that limit carrier extraction. The origin of these losses is discussed in terms of the material regions where recombination takes place. Our results indicate that carrier extraction is most efficient from the Si NCs themselves, whereas recombination is strongest in SiC and residual a-Si domains . Together with the observed onset of the external quantum efficiency (EQE) at 700-800 nm, this fact is an evidence of quantum confinement in Si NCs embedded in SiC on device level.

This master thesis explores the integration of Artificial Intelligence (AI) in Environmental, Social, and Governance (ESG) reporting, focusing on its potential to enhance the accuracy, transparency, and efficiency of ESG disclosures. It investigates how AI can transform ESG reporting from a reactive to a proactive tool, enabling companies to better assess and mitigate ESG-related risks. The study examines the perceptions of industry professionals regarding AI's role in ESG, considering factors such as age, education, and professional background. It highlights the significant impact AI can have on sectors like finance, energy, and healthcare, while addressing challenges and ethical concerns. The findings suggest that AI can be a powerful enabler of ESG transparency, but its adoption requires sector-specific adaptations and careful ethical considerations. Future research is recommended to explore long-term effects and deeper ethical issues in AI-driven ESG reporting. Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura Objectius de Desenvolupament Sostenible::16 - Pau, Justícia i Institucions Sòlides

Thermo-economically optimal design = optimal molecule + optimal process + optimal equipment.

Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles::11.6 - Per a 2030, reduir l’impacte ambiental negatiu per capita de les ciutats, amb especial atenció a la qualitat de l’aire, així com a la gestió dels residus municipals i d’altre tipus 2n Premi Domènec Valero 2024 Award-winning

The opportunities and challenges of applying micronutrients (MiNs) in full-scale anaerobic digestion (AD) plants has been reviewed. The review discusses the underlying mechanisms and the role of different micronutrients (Fe, Ni, Co, Mo, Zn, Cu, Se) in the enhancement of AD performance, as well as their environmental and economic implications in full-scale AD systems. Bioavailability is a key factor affecting the effectiveness of micronutrients application on the biochemical aspects of AD. Accordingly, the technical aspects of AD with a direct impact on bioavailability have been identified and critically addressed. Mono-supplementation is not the most favorable strategy to increase micronutrient bioavailability due to limited solubility, formation of insoluble compounds, interaction with other compounds, and specific microbial requirements. Nonetheless, co-supplementation can increase the bioavailability due to the simultaneous synergetic effects of co-micronutrients supplementation on the biochemical aspects of AD. However, the inconsistency of reported lab-scale results and the lack of protocols or guidelines for analyzing the bioavailability of micronutrients limit results interpretation and full-scale application. The environmental and economic implications of these micronutrients are other critical factors that need further research. The economic results showed that the mono-supplementation can be economically favorable when a methane enhancement of 20% is achieved. Co-supplementation of micronutrients is the most economically feasible option since this strategy allows reducing the total dosage of micronutrients when compared with mono-supplementation. The authors are grateful for the scholarship from the TUM SEED Center of the Technical University of Munich, which is part of the DAAD (German Academic Exchange Service) program “exceed” supported by DAAD as well as the German Federal Ministry for Economic Cooperation and Development (BMZ) and in cooperation with the hosting Chair of Urban Water System Engineering of TUM. Sergi Astals is thankful to the Spanish Ministry of Science, Innovation and Universities for his Ramon y Cajal. Peer Reviewed

Pump as turbine (PAT) is a common method of energy recovery, however, vortices are a negative phenom for these units. The objective of this research is to study the effect of vortex motion on the hydraulic loss of pump as turbine, and establishing the correlation mechanism between vortex intensity and turbulence loss. The research method adopts theoretical analysis and model test and numerical simulation. Based on the entropy production theory, the hydraulic loss and the turbulent dissipation in boundary layer induced by vortex motion are studied, revealing the influence of vortices on the energy loss. Results show that the vortex motion can be decomposed into a synchronous component v_sy and a rotational component v_ro, among them, the rotational component v_ro meets to Biot-Savart Law. The turbulent dissipation rate in the boundary layer is closely to the vortex motion, which can characterize the boundary turbulence height. Turbulent flow induced by vortex can propagate in the flow channel of the unit, causing lot of additional hydraulic loss. In the end, a mathematical model between entropy production (Sk) induced by vortex and vortex strength (¿k) was established, indicating that Sk changes with ¿k in the form of a quadratic function.

The primary objective of this paper is to develop a hybrid grey box model that integrates air and thermal dynamics to improve accuracy in both domains. The methodology involved developing four grey box models to estimate ventilation airflows using indoor CO2 concentration data and six thermal models to estimate thermal properties and heat gains using indoor temperature data. To ensure accurate parameterization, measurements of outdoor conditions, occupancy, and HVAC operations were incorporated. The results revealed that models treating infiltration and mechanical ventilation as mutually exclusive (IAQ-3 and IAQ-4) and those integrating ventilation heat gains from estimated airflows (T-6) performed most effectively. This hybrid approach underscores the benefits of incorporating ventilation heat loos or gains, based on airflow estimation derived from indoor air quality (IAQ) models, into thermal modelling, significantly improving accuracy and reducing parameter variability. The findings demonstrate the potential of this methodology for applications in ventilation management and HVAC optimization. By enhancing energy efficiency and improving indoor air quality, this approach supports the development of healthier, more sustainable indoor environments. This research was supported by a predoctoral contract grant (reference no. PRE2021-099606) as part of the research and development project IAQ4EDU (reference no. PID2020-117366RB-I00), funded by MCIN/AEI/10.13039/501100011033/FEDER, and is part of the project BINAFET (reference no. TED2021-130047B-C22), funded by MCIN/AEI/10.13039/501100011033 and by the European Union “NextGenerationEU”/PRTR. Moreover, this study was supported by the Catalan agency AGAUR through its research group support programme (2021 SGR 00341).