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Optimizing Magnetron Performance: a Study on Noise Reduction Techniques and Power Supply Effects
No full text[EN] This undergraduate thesis focuses on optimizing cooking magnetron performance by characterizing its signal noise and identifying main sources to explore its use in particle accelerators. While magnetrons are highly efficient, their noisy and unstable signal limits high-precision applications. Key noise sources include thermal, shot, and flicker noise. The DC power supply ripple causes significant frequency oscillations and contributes to amplitude modulation (AM) noise. Electron angular velocity also generates AM modulation signals.
Noise characterization revealed that increasing power reduces total noise and compresses AM noise. Injection locking significantly improves noise, particularly phase noise, with reductions up to 30 dB near the carrier. It also mitigates frequency oscillations and reduces AM noise near the carrier, though it can worsen it further from the carrier. However, injection locking can also exacerbate the DC supply ripple, complicating measurements. Future work should focus on redesigning the DC supply to filter ripple for magnetron use in particle accelerators
Estimation of longitudinal and transverse stiffness of hemp fibers and their composites using experimental material parameters and invariants
No full textThe use of hemp is becoming increasingly favored due to its low carbonfootprint and biodegradability advantages combined with its low density, highspecific stiffness, and strength. This paper aims to simplify, normalize, and pre-sent published experimental data on the stiffness of long unidirectional hempcomposites to avoid dispersion and to provide new effective stiffness parame-ters for comparison with other composites. Trace normalized values of longitu-dinal, transverse, and shear moduli of untreated and treated long hempcomposites were calculated based on over 100 tensile experimental values nor-malized to a volume fraction of 0.4% for comparison. The trace normalizedlongitudinal stiffness values of untreated and chemically modified hemp com-posites are 0.7 and 0.85, with a coefficient of variation of 4.8% and 6.8%, respec-tively. These are comparable with non-natural composites such as carbon(0.88), Kevlar (0.88) and flax (0.78). Predicting moduli of composites andmicromechanics has been used to obtain back-calculations, leading to anaverage value for hemp fiber of 56.3 GPa longitudinal modulus, 6.8 GPa fortransverse moduli, and 7.4 GPa for shear. The relationship between the longi-tudinal modulus and the U2 parameter was found to be linear, with a ratio of0.42 and 0.48 for hemp and chemically modified composites, respectively. Dueto the limited experimental data available, only preliminary compressionresults are presented.Highlights• Simple estimation of transverse and shear modulus of hemp composites andfibers.• Influence of treatment on the stiffness of hemp composites.• Experimental material properties of hemp composites.• Stiffness comparison between composites at a volume fraction of 0.4%
Tensiones y encuentro con el mercado: Prácticas autogestionarias de las y los jóvenes raperos de Lima Sur, Perú.
No full text468 p.La pesquisa indaga en las prácticas autogestionarias desenvueltas por las y los jóvenes raperos de los distritos del sur de la ciudad de Lima, Perú. Busca recoger evidencias sobre estas prácticas, producidas de manera autónoma y sin demandar la compra o venta de fuerza de trabajo, el pago de salario o la intermediación del mercado; reconstruir los procesos históricos y estructurales que favorecen su insurgencia; y analizar sus características. Asume como hipótesis que estas prácticas autogestionarias son desenvueltas en tensión con el mercado capitalista, es decir, no lo reemplazan y tampoco pueden ser generadas al margen de él; del mismo modo, no responden únicamente a su racionalidad, interesada en ganar y generar beneficios, sino que instituciones como la familia y la comunidad terminan animando otras racionalidades, donde no es demandada la compra o venta de fuerza de trabajo, el pago de salario o la intermediación del mercado; pero donde es posible apreciar el ejercicio de la autonomía y la afirmación de la individualidad
Environmental assessment of a hydrogen supply chain using LOHC system with novel low-PGM catalysts: A life cycle approach
No full textHydrogen has emerged as a key element in the transition to a sustainable energy model. Among hydrogen storage and transport technologies, liquid organic hydrogen carriers (LOHCs) stand out as a promising alternative for
large-scale, long-term use. Catalysts, essential in these systems, are usually composed of platinum group metals (PGMs) over alumina, known for their high cost and scarcity. This study analyzes the overall environmental impact of the LOHC benzyltoluene/perhydro-benzyltoluene-based hydrogen supply chain by means of the life cycle assessment (LCA), focusing on the synthesis processes of novel low-PGM catalysts, which remain underexplored in existing literature. The results identify dehydrogenation as the most impactful step due to significant heat consumption, and highlight the substantial environmental footprint associated with the use of platinum in catalyst production. This research provides crucial insights into the environmental implications of LOHC systems, particularly the role of novel low-PGM catalysts, and offers guidance for their future large-scale applications.This work was supported by the University of the Basque Country (UPV/EHU), Basque Government (Project: IT1554-22) and Clean Hydrogen Partnership [grant agreement number 101111964]. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and Innovation programme, Hydrogen Europe, and Hydrogen Europe research. Grant PID2020-112889RB-I00 funded by: MCIN/AEI/10.13039/501100011033
Wind farm analysis using SailoR diagram-based diagnostics to quantify yaw misalignment correction
No full textThis study introduces a novel application of indices derived from the SailoR diagram for detecting and
correcting yaw misalignment in wind turbines, which involves an original visualization of principal component
analysis. The angular disparity between principal components, visualized as ellipses on the SailoR diagram,
serves as a metric for comparing deviations between anemometers within a designated group (External
Deviation index) and between the turbine’s anemometer and its yaw angle system (Internal Deviation index).
A normalized criterion, incorporating anomalies in power production (Power Bias index), yaw angle, and
absolute angle deviation, is established to compare the error of each turbine relative to its respective
group. By integrating these indices with the general deviation of each turbine, the analysis effectively
discriminates between external and internal error sources and quantifies the magnitude of each deviation. A
case study involving a real wind farm with three distinct turbine groups demonstrates the efficacy of this
integrated methodology as a valuable tool for initial diagnosis, enabling the identification, discrimination
(internal/external), and quantification of yaw misalignment.This study is part of project PID2020-116153RB-I00 fundedby Ministerio de Ciencia e Innovación/Agencia Estatal de InvestigaciónMCIN/AEI/10.13039/501100011033. The authors thankfully acknowl-edge HAZITEK-2023 grant GEDIQUAN ZL-2023/00281 of the BasqueGovernment (Eusko Jaurlaritza).
All the calculations have been carried out in R programming lan-guage (https://www.r-project.org/) and the corresponding SailoR pack-age created by the authors has been also used (https://cran.r-project.org/web/packages/SailoR/index.html)
Analysis of ICT Energy Efficiency Disclosure to Improve Business Management Practices and Its Contribution to the SDGs
No full textAbstract: Purpose: The new global approach to sustainability within the context of the
SDGs is driving a digital transition. However, new technologies bring challenges related to
the energy efficiency of their infrastructures. The aim of this exploratory work is to identify
the companies with best practices in various aspects of the management, disclosure and verification
of the energy efficiency of emerging technologies. Design/methodology/approach:
Using a mixed qualitative and quantitative approach, the Non-Financial Information
Statements of Spanish IBEX 35 companies are assessed. Findings: The results show that
companies disclose non-financial information in relation to the materiality of energy efficiency
and the actions implemented to improve it, but regulatory development is still
required to ensure greater comparability of such information. Originality: To the best of
our knowledge, this is the first study to analyse information on ICT energy sustainability
in the context of Law 11/2008 in Spain, which also includes an analysis of information on
the double materiality of risks and the policies and actions implemented by companies to
manage them. Practical implications: Improving the information disclosed will increase
its usefulness for the internal decision-making of companies, to improve ICT energy efficiency
and SDG. Social implications: Improving the information disclosed will increase its
usefulness for external decision-making by the different stakeholders, as regulators and
other disclosing companies may take these selected companies as an example in each sector
of activity.This research was funded by Consolidated Research Group of the Eusko Jaurlaritza (EJ/GV)—grant number [IT1523-22]
Entre la esperanza y el obstáculo: una mirada cualitativa a las expectativas y realidades de la reinserción social post penitenciaria
Get PDFEl presente Trabajo de Fin de Grado tiene como objetivo analizar las barreras estructurales que dificultan la reinserción social de las personas expresas, centrándose específicamente en tres dimensiones clave: el acceso al empleo, la vivienda y el apoyo familiar o comunitario. Para ello, se realiza un análisis normativo del marco legal europeo y español que regula el proceso de reinserción, contrastado posteriormente con los resultados del trabajo de campo, que ha consistido en dos entrevistas semiestructuradas a internos próximos a salir y a expresos en libertad. Esta investigación no solo profundiza en el impacto del estigma social y la falta de apoyo institucional, sino que también permite reflexionar sobre el papel de las instituciones públicas y privadas en dicho proceso. A partir de los testimonios recogidos y de un enfoque criminológico crítico, se proponen posibles mejoras en las políticas de reinserción que promuevan una integración real y efectiva, conforme al artículo 25.2 de la Constitución español
Reliable Explainability of Deep Learning Spatial-Spectral Classifiers for Improved Semantic Segmentation in Autonomous Driving
Get PDFIntegrating hyperspectral imagery (HSI) with deep neural networks (DNNs) can strengthen the accuracy of intelligent vision systems by combining spectral and spatial information, which is useful for tasks like semantic segmentation in autonomous driving. To advance research in such safety-critical systems, determining the precise contribution of spectral information to complex DNNs' output is needed. To address this, several saliency methods, such as class activation maps (CAM), have been proposed primarily for image classification. However, recent studies have raised concerns regarding their reliability. In this paper, we address their limitations and propose an alternative approach by leveraging the data provided by activations and weights from relevant DNN layers to better capture the relationship between input features and predictions. The study aims to assess the superior performance of HSI compared to 3-channel and single-channel DNNs. We also address the influence of spectral signature normalization for enhancing DNN robustness in real-world driving conditions.This work was partially supported by the University of the Basque Country (UPV-EHU) under grant GIU21/007, by the Basque Government under grants PRE 2023 2 0148 and KK-2023/00090, and by the Spanish Ministry of Science and Innovation under grant PID2020-115375RB-I00
The Biogeography of Soil Bacteria in Australia Exhibits Greater Resistance to Climate Change Than Fungi
No full textSoil microorganisms are crucial to ecosystem health, and their composition and distribution are shaped by a range of environmental factors. However, the effects of accelerating climate change on soil microbiomes remain under-explored. This study examines the continental-scale factors controlling soil microbiomes and evaluates their responses to climate change. We applied machine learning algorithms to analyze the distribution patterns of bacteria and fungi in 1300 Australian topsoil samples. Our results indicate that bacterial distributions align closely with the soil class map, highlighting the dominant impact of soil properties. In contrast, fungal distributions are more strongly associated with temperature gradients, emphasizing the critical role of climate. Climate projections for 2040 suggest a notable southward shift in both bacterial and fungal patterns, particularly around latitude 25° S. Moreover, our findings suggest that fungal biogeography is likely to undergo more pronounced changes, with approximately 24% of Australian topsoils expected to experience significant shifts in fungal community structure, compared to about 19% for bacteria, which appear more resistant. This study emphasizes the diverse vulnerabilities of soil microbial communities and stresses the need to account for microbial dynamics in future land use and management practices.Funding: This work was supported by Australian Government, Department of Agriculture, Fisheries, and Forestry (4-H4T0RYS). We would like to acknowledge the contributions of the Biomes of Australian Soil Environments (BASE) projects and National Geochemical Survey of Australia (NGSA) supported by Australian Government funding. We acknowledge the landowners (be they traditional, private, or business owners) for access to sample sites. The study is supported by Soil Science Challenge Grant 4-H4T0RYS from the Australian Department of Agriculture, Fisheries, and Forestry. Open access publishing facilitated by The University of Sydney, as part of the Wiley - The University of Sydney agreement via the Council of Australian University Librarians. We would like to acknowledge the contributions of the Biomes of Australian Soil Environments (BASE) projects and National Geochemical Survey of Australia (NGSA) supported by Australian Government funding. We acknowledge the landowners (be they traditional, private, or business owners) for access to sample sites. The study is supported by Soil Science Challenge Grant 4\u2010H4T0RYS from the Australian Department of Agriculture, Fisheries, and Forestry. Open access publishing facilitated by The University of Sydney, as part of the Wiley \u2010 The University of Sydney agreement via the Council of Australian University Librarians
Karbono nitruroan eta titanio dioxidoan oinarritutako MOFen ezarpena karbono dioxidoaren erredukziorako
No full textKarbono dioxidoaren (CO₂) biltegiratzea eta berrerabilpena klima-aldaketa arintzeko erronka handienetako bat dira. CO₂ betirako lurpean biltegiratu daitekeen arren, alternatiba bat konposatu kimiko eta erregai baliotsu bihurtzea da katalisi-prozesuen bidez. Metodo horien artean, CO₂ren fotoredukzioa bide jasangarri bat da, eguzki-energia erabiliz karbono-konposatu bihurtzeko. Hala ere, prozesu honen eraginkortasuna nagusiki fotoaktibo gisa erabiltzen diren katalizatzaileen aukeraketaren eta haien egiturazko propietateen araberakoa da.
Karbono nitruroa (C₃N₄) eta titanio dioxidoa (TiO₂) bezalako material fotoaktiboek funtsezko eginkizuna dute CO₂ren fotoredukzioan, katalizatzaile gisa jardunez, argia xurgatu eta erreakzioa erraztuz. Katalisiaren errendimendua hobetzeko, material mesoporotsuak gehitu daitezke CO₂ren xurgapena handitzeko, gainazal-eremu handiagoa eta difusio-bide eraginkorragoak eskainiz. Horrez gain, material hauetan metalezko-organikoen egiturak (MOF) integratzea estrategia eraginkorra da, substratuaren espezifikotasuna, selektibitatea eta eraginkortasun orokorra hobetzeko. MOFak poro handia, egitura doigarria eta gune metaliko aktiboak dituzten materialak dira, eta erreakzio-bideak eraldatu eta CO₂ aktibazioan lagundu dezakete
Hala ere, MOFen eta fotoaktiboen euskarriaren arteko elkarrekintzak eragin nabarmena du egonkortasun estrukturalean, karga-transferentziaren dinamikan eta eraginkortasun katalitikoan. MOFak oso sentikorrak dira hazkuntza-ingurunearen eta interfazean gertatzen diren interakzioen aurrean, eta, ondorioz, euskarri-materialaren hautaketak MOFen portaeran eragina du MOF@euskarri heterojuntzioetan. Azalera-kimika, porositatea eta propietate elektronikoak bezalako faktoreen aldeek karbono nitruroaren eta titanio dioxidoaren gainean MOFen nukleazioa, hazkundea eta katalizatzailearekiko interakzioa baldintzatuko dute, eta, azken batean, CO₂ren fotoredukzioaren jarduera baldintzatuko dute.
Ikerketa honek HKUST-1 MOFa bi euskarri fotoaktibo ezberdinetan haztearen eragina aztertzen du: karbono nitruro grafitiko mesoporotsua (mpg-C₃N₄) eta titanio dioxidoa (TiO₂). Geruzaz geruza gehiketa-metodo bat erabiliz, gainazaleko lotura, interfazean gertatzen den karga-transferentzia eta elkarrekintza katalitikoak aztertzen ditugu CO₂ren fotoredukzioan. Esperimentuak batch sistema itxi batean egiten dira, ura elektroi emaile gisa erabiliz, erreakzio-baldintza kontrolatuetan fotokatalizatzaile-MOF konbinazio ezberdinen errendimendua alderatzeko. HKUST-1 material hauekin nola integratzen den ulertzeak aukera emango du hibrido fotoaktiboak optimizatzeko, CO₂ren bihurtze-eraginkortasuna, produktu-selektibitatea eta epe luzerako egonkortasuna hobetzeko, eguzki-energia bidezko karbono-berrerabilpen teknologiak garatzeko