Donostia International Physics Center
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Desarrollo de recubrimientos autolubricantes para mecanismos espaciales
No full textEl desarrollo de la industria aeroespacial ha llevado a la búsqueda de soluciones innovadoras para garantizar el éxito y la fiabilidad de misiones cada vez más exigentes. Uno de los principales desafíos en este ámbito es la durabilidad de los sistemas tribológicos, ya que la fricción y el desgaste de los componentes mecánicos pueden comprometer el rendimiento de los mecanismos en el espacio. Los recubrimientos Diamon-like carbon (DLC) han surgido como una alternativa prometedora para la autolubricación en condiciones de vacío, reduciendo la fricción y prolongando la vida útil de los sistemas de transmisión en entornos espaciales.
Este trabajo se centra en el desarrollo y caracterización de recubrimientos autolubricantes DLC aplicados sobre sustratos de acero 100Cr6, con el objetivo de mejorar su desempeño tribológico en condiciones similares a las del espacio. Para ello, se ha seguido una metodología estructurada en varias fases, que incluyen la caracterización de los recubrimientos mediante espectroscopía Raman, ensayos de dureza y adhesión, y la evaluación de su rendimiento tribológico mediante pruebas ball on disc en un tribómetro de vacío.
Los resultados obtenidos permiten establecer correlaciones entre la composición química, la microestructura y el comportamiento tribológico de los recubrimientos, identificando aquellos parámetros clave que favorecen la formación de tribofilms autolubricantes. Se ha observado que la presencia de hidrógeno en la matriz DLC influye directamente en sus propiedades mecánicas y tribológicas. En particular, los recubrimientos con un contenido de hidrógeno cercano al 40% muestran una mayor capacidad autolubricante y un mejor rendimiento en aplicaciones espaciales. En contraste, aquellos con menor contenido de hidrógeno presentan una respuesta menos favorable, con un incremento en la fricción y una menor resistencia al desgaste en vacío.
A partir de los resultados obtenidos, se abre la posibilidad de continuar con estudios a nivel de componente, con el fin de evaluar su viabilidad en sistemas reales y avanzar hacia su implementación en futuras misiones espaciales
New York City 2100: Environmental justice implications of future scenarios for addressing extreme heat
No full textClimate-driven hazards, such as extreme heat or precipitation, are threatening the current and future livability of New York City (NYC) and disproportionately affecting low-income communities and communities of color. To envision future climate resilience, government stakeholders and researchers co-produced future scenarios for 2100 in response to climate hazards for NYC during participatory workshops in Fall 2021. A commonly co-produced strategy included urban green infrastructure (UGI) because of its potential to retain runoff and provide cooling benefits. We ask, what are the potential environmental justice implications of ecosystem services provisioned from UGI distribution in the co-produced NYC future scenario compared to a business-as-usual future scenario? To analyze potential outcomes and tradeoffs, we integrated spatially-explicit UGI strategies into simulated land use and cover models. We then assessed two ecosystem services (flood and heat mitigation) using the spatially-explicit tool Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST). We explored potential environmental justice implications by comparing the provision of ecosystem services to sociodemographic indicators within census block groups between scenarios. Presently, ecosystem services are disproportionately lower for communities of color, including predominantly Asian, Black/African-American, and Hispanic/Latino communities. In future scenarios we found ecosystem service provision will decrease within these communities under business-as-usual land development. The future scenario co-produced for extreme heat resilience, however, shows an increase in overall provisioning across NYC, including in neighborhoods with a high proportion of people of color. Our results show that co-produced future scenarios can be used to inform strategic future planning for inclusive adaptation decisions to improve future climate resilience and justice. © 2024 The Author(s)We would like to thank Adam Parris for his collaboration and coorganizing the NYC Climate Adaptation workshop series, Daniela Tagtachian for facilitating the co-production of the NYC 2100 Heat Resilience scenario, and all participants of the workshop series for sharing their insights for future climate resilience. We also acknowledge support for this project from NSF SETS Growing Convergence Research (#1934933) and NATURA (#1927167) projects and the Columbia University E3B department. PHC was supported by the Doctoral INPhINIT–INCOMING program, fellowship code (LCF/BQ/DI22/ 11940028), from “La Caixa” Foundation (ID 100010434)
Crystal structure, magnetic and magnetocaloric properties of the new orthorhombic Y3Co2-type Gd3Co1+xNi1−x solid solution
No full textThis work reports the existence of the new rare-earth intermetallic compound Gd3Co1+xNi1-x (with x = 0.1, 0.2, 0.3, and 0.4) and the investigation of its crystallographic, magnetic, and magnetocaloric properties. Gd3Co1+xNi1-x is a novel solid solution phase that crystallizes in the orthorhombic Y3Co2-type structure [oP20, Pnmm (No. 58)]. It constitutes the first representative of a compound crystallizing in this structural prototype. The research also includes an analysis of the critical behavior associated with the second-order phase transition from a paramagnetic to a ferromagnetic state (PM-FM) detected in the compound. This analysis indicates that short-range order isotropic magnetic interactions are present, consistent with the 3D Heisenberg model. Increasing the Co content leads to a higher Curie temperature (TC), thus, shifting the peak of the magnetic entropy change, while maintaining the overall physical properties. This demonstrates the potential of tuning the working temperature region by modifying the Co/Ni concentration without negatively affecting the magnetocaloric properties. For μ_0 ∆H=5 T, the magnetic entropy change peaks range between 7.81 and 8.40 J kg-1K-1, while the refrigerant capacity values are around 600 J kg-1. These results place this family among the top performing ones in their working temperature region. The scaling relations and the universal curve confirm the second-order nature of the phase transition and validate the calculated critical exponents.Departamento de Educación del Gobierno Vasco (project IT1430-22
Una estatua colosal del foro de Los Bañales (Uncastillo, Zaragoza)
No full textEn las excavaciones realizadas en el foro de Los Bañales de Uncastillo fue localizado un importante programa escultórico localizado en la zona sur del conjunto en una unidad de amortización. El presente trabajo estudia unos fragmentos escultóricos pertene-cientes a una representación de tamaño colosal que se ubicó en el forum de la ciudad. El ta-maño de la escultura contrasta con el exiguo tamaño del foro de Los Bañales, lo que no im-pidió exhibir una estatua de estas dimensiones. Este nuevo ejemplo de escultura colosal en comunidades de tamaño medio y pequeño nos muestra que estas representaciones no fueron exclusivas de las grandes ciudades hispanas.; During the excavations at the forum of Los Bañales de Uncastillo, an important sculptural program was discovered in the southern area of the complex. This paper studies some sculptural fragments belonging to a colossal representation that was located in the city’s forum. The size of the sculpture contrasts with the small size of the forum at Los Bañales, which did not prevent the display of a statue of these dimensions. This new example of colossal sculpture in medium and small-sized communities shows us that these representations were not exclusive to the large cities in Hispania
Matematika baratzean, Matematika baratzearekin
No full textMatematika baratzean, Matematika baratzearekin izeneko iburuxka honetan baratzea testuinguru modura erabiltzen duten hamar jarduera didaktiko eskaintzen dira, Lehen Hezkuntzan matematika lantzeko. Baratzean bertan kokatuz (tokiko ikaskuntza) eta metodologia aktiboak erabiliz, inplementatzeko proposatzen diren jarduera didaktikoen bidez ikasleek ikuspegi eta arrazoibide matematikoak garatu eta aplikatuko dituzte hainbat problema ebazteko. Matematikarekiko ikasleen motibazioa areagotzeaz gain, kontzeptuen ulermen sakonagoa izatea lortu nahi da, errealitatean baratzean gerta daitezkeen prozesu eta jardueren bidez. Finean, matematika arlotik bideratuta, ikaslearen ikaskuntza esanguratsua eta integrala osatu nahi da.
Planteatzen diren matematikako jarduerak inplementatu egin dira Arabako Campuseko baratze ekologikoan bertan, Hezkuntza eta Kirol Fakultateko (UPV/EHU) Lehen Hezkuntzako irakaslegaiekin Matematika eta bere Didaktika II irakasgaian. Era horretan, etorkizuneko maisu-maistrek soinean daramate geroan eskolan abia dezaketen ikas-irakaskuntza metodologia osagarria. Horrez gain, jarduera batzuk eskoletako ikasle eta irakasleekin inplementatu ditugu. Irakasleen esku geratzen da zeintzuk jarduera egin eta zein ordenatan, edota nola moldatu jarduera bakoitza bere egoera eta etapa akademikora. Geroko maisu-maistren formaziorako egokia eta Lehen Hezkuntzako irakasleentzako material baliagarria eta erabilerraza izatea espero dugu.Matematika baratzean, Matematika baratzearekin izeneko iburuxka honetan baratzea testuinguru modura erabiltzen duten hamar jarduera didaktiko eskaintzen dira, Lehen Hezkuntzan matematika lantzeko. Baratzean bertan kokatuz (tokiko ikaskuntza) eta metodologia aktiboak erabiliz, inplementatzeko proposatzen diren jarduera didaktikoen bidez ikasleek ikuspegi eta arrazoibide matematikoak garatu eta aplikatuko dituzte hainbat problema ebazteko. Matematikarekiko ikasleen motibazioa areagotzeaz gain, kontzeptuen ulermen sakonagoa izatea lortu nahi da, errealitatean baratzean gerta daitezkeen prozesu eta jardueren bidez. Finean, matematika arlotik bideratuta, ikaslearen ikaskuntza esanguratsua eta integrala osatu nahi da.
Planteatzen diren matematikako jarduerak inplementatu egin dira Arabako Campuseko baratze ekologikoan bertan, Hezkuntza eta Kirol Fakultateko (UPV/EHU) Lehen Hezkuntzako irakaslegaiekin Matematika eta bere Didaktika II irakasgaian. Era horretan, etorkizuneko maisu-maistrek soinean daramate geroan eskolan abia dezaketen ikas-irakaskuntza metodologia osagarria. Horrez gain, jarduera batzuk eskoletako ikasle eta irakasleekin inplementatu ditugu. Irakasleen esku geratzen da zeintzuk jarduera egin eta zein ordenatan, edota nola moldatu jarduera bakoitza bere egoera eta etapa akademikora. Geroko maisu-maistren formaziorako egokia eta Lehen Hezkuntzako irakasleentzako material baliagarria eta erabilerraza izatea espero dugu.Eskerrak eman nahi dizkiegu Eusko Jaurlaritzari eta Euskal Herriko Unibertsitateari, lan honen finantziazioarekin laguntzeagatik. Eusko Jaurlaritzak “STEAM2Net Ikerkuntza-Hezkuntza Sarea” (HEZKUNTZA23/17) proiektuaren bitartez finantzatu du lana, eta UPV/EHUk Iraunkortasun eta Gizarte Konpromisorako Zuzendaritzaren bitarte
Enhanced hydrogen production reversibility in the MnFe₂O₄-Na₂CO₃ thermochemical cycle via synergistic effect of liquid carbonate and CeO₂ nanoparticles
No full textThis study investigates the addition of 3 wt% of TiO₂, SiO₂, and CeO₂ nanoparticles as an anti-sintering strategy to enhance the reversibility of sodium manganese ferrite for hydrogen production. After preliminary tests, TiO₂ NPs were discarded due to cross-reactivity leading to pronounced sintering. SiO₂ NPs hindered the sintering due to the in-situ formation of NaFeO2,SiO2 solid solution but ultimately resulted in irreversible H₂ production. In contrast, CeO₂ NPs demonstrated high stability and chemical compatibility, stabilizing H₂ production at approximately 50 μmol/g, while the reference mixture monotonically lost reversibility in 5 cycles. Notably, combining CeO₂ NPs with a eutectoid (Na0.93Li0.07)2CO3 mixture enhanced H₂ production to 0.18/0.19 mmol/g. As a result, the H2 produced during the 5th cycle was nearly twenty times that of the reference mixture. This improvement was attributed to a synergistic effect between the formation of liquid carbonate and the anti-sintering and oxygen gateway effect of the CeO2 NPs.This project has received funding from the European Union NextGenerationEU (H2PLAN-KC-2021/00002) and the Department of Economic Development, Sustainability and Environment of the Basque Government H2BASQUE-KK-2021/00054
Vacuum frying as an alternative technique to increase the oxidative stability of sunflower oil. A comprehensive 1H NMR and SPME-GC/MS study focused on oxygenated compounds
No full textThe present study compares the oxidative stability of sunflower oil during vacuum frying (120 °C, low pressure) and conventional frying (170 °C, atmospheric pressure), focusing on the formation of oxygenated oxidation products. To discern between the effects of temperature and reduced concentration of oxygen during vacuum frying, the stability of sunflower oil under atmospheric frying conditions at 120 °C was also evaluated. Oil samples were analysed using Proton Nuclear Magnetic Resonance (1H NMR) and Solid Phase Microextraction (SPME) followed by Gas Chromatography/Mass Spectrometry (GC/MS). Additionally, the percentage of Total Polar Compounds (TPC) and the viscosity were determined. Under vacuum frying conditions, the degradation rate of linoleate was slower than under atmospheric frying conditions. Likewise, the formation of different oxygenated oxidation compounds, including monohydroperoxy- monohydroxy- and monoketo-conjugated-octadecadienoates, Z-monoepoxy-Z-octadecenoates and aldehydes, some of which are potentially harmful, was also delayed. Similarly, the evolution of the TPC percentage and viscosity changes showed a slower rate. These results provide, for the first time, a comprehensive understanding of the effect of vacuum frying on the stability of sunflower oil, highlighting its potential as a promising alternative to conventional frying methods.This work has been supported by the Spanish Ministry of Science, Innovation and Universities (research project PID2021-123521OB-I00 funded by MCIU/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”), as well as by the Basque Government (EJ-GV IT1490-22)
Meat alternative adoption: How climate change concern drives perceived sustainability, naturalness, and taste
No full textConventional livestock production generates high amounts of greenhouse gas emissions, significantly contributing to man-made climate change. Switching to meat alternatives has the potential to curb meat consumption but faces obstacles rooted in consumers’ concerns about unnaturalness, negative health implications, and excessive processing. Drawing on environmental psychology, heuristic processing, consistency theory, and the halo effect, this study develops a conceptual framework on how consumer’s climate concern, by activating climate commitment, not only directly motivates the adoption of meat alternatives, but also triggers perceptual processes, that have a favorable effect on the perception of the attributes of meat alternative products. The theoretical model was tested with an online survey of a US representative sample (N=800). Results show that climate concern positively affects meat alternative adoption by activating climate commitment. Climate commitment, in turn, through the drive for internal consistency and the halo effect, enhances the perceived sustainability, naturalness, and taste of meat alternatives, boosting their acceptance. Findings contribute to the literature by introducing a novel mechanism involving mental shortcuts based on consistency theory and the halo effect, which suggests that consumers align food product perceptions with their environmental goals. These insights offer valuable guidance for policymakers and marketers to design effective interventions promoting more sustainable dietary choices.This work was supported by funding received from the Spanish Government and European Regional Development Fund [Grant PID2021-123686OB-I00 funded by MICIU/AEI/10.13039/501100011033 and by ERDF A way of making Europe], the Basque Government [Grant IT1731-22], and FESIDE Foundation
Balancing robustness and efficiency in embedded DNNs through activation function selection
No full textMachine learning-based embedded systems for safety-critical applications, such as aerospace and autonomous driving, must be robust to perturbations caused by soft errors. As transistor geometries shrink and voltages decrease, modern electronic devices become more susceptible to background radiation, increasing the concern about failures produced by soft errors. The resilience of deep neural networks (DNNs) to these errors depends not only on target device technology but also on model structure and the numerical representation and arithmetic precision of their parameters. Compression techniques like pruning and quantisation, used to reduce memory footprint and computational complexity, alter both model structure and representation, affecting soft error robustness. In this regard, although often overlooked, the choice of activation functions (AFs) impacts not only accuracy and trainability but also compressibility and error resilience. This paper explores the use of bounded AFs to enhance robustness against parameter perturbations, while evaluating their effects on model accuracy, compressibility, and computational load with a technology-agnostic approach. We focus on encoder–decoder convolutional models developed for semantic segmentation of hyperspectral images with application to autonomous driving systems. Experiments are conducted on an AMD-Xilinx's KV260 SoM
Performance of Autistic Adults on Conversational Implicatures: A Comparison of Material and Behavioural Inferences
No full textThis paper compares the performance of autistic and neurotypical participants in discourse-completion tasks that require the identification of two types of particularised conversational implicature. Material implicatures are those in which the inferential relationship from what is said to the implicature can be reconstructed without recourse to descriptions of the speaker's behaviour and the reasons underlying it, while behavioural implicatures do require such descriptions. We hypothesised that autistic participants would perform on a par with neurotypical participants in the material cases, but less well than neurotypicals in the behavioural cases, given that the latter make greater demands on theory of mind. In fact, we found that autistic participants’ performance mirrored that of neurotypicals in both conditions. We note a general tendency in the literature for autistic individuals to perform well on tests of comprehending implicit communication, in contrast to attested and self-reported difficulties in this area. We speculate that this mismatch might be explained in terms of a difference in underlying competence and the performance demands of real-world interactions.This research has been partially supported by project FUNLAT (PID2021-122233OB-I00), funded by MICIU/AEI/10.13039/501100011033 and by “ERDF/EU”, and by the IT1537-22 Research Group (Basque Government)