bluuebunny/crossref_metadata_2025 huggingface dataset:
SINGLE-ELECTRON NANOSUMMER WITH MAJORITY SELECTION
Authors: Melnyk Oleksandr Stepanovych , Viktoriia Oleksandrivna Kozarevych
Published: September 2024

Single-electron devices are a promising technology of digital nanoelectronics, in which a bit of information is encoded by the presence or absence of an electron. In such devices, electron movement occurs due to tunneling or Coulomb blockade processes. The theoretical speed limit of single-electron devices is extremely high, since tunneling is inertialess, and the energy of electron movement is extremely small. As a result, the theoretical speed lim- it of single-electron devices is hundreds of terahertz, and the consumed energy does not exceed one attojoule. The article is devoted to the introduction of a new one-electron full one-bit nanoadder on a five-way majority element for computer modeling and design of highly efficient four-bit adder- subtractors. The developed arithmetic logic devices use the technology of quantum cellular automata. The created nanoadder uses only 231 quantum cells on a crystal with an area of 0, 49 μm2 . Logical operation delays and switching energy density of the cells themselves are significantly reduced compared to existing prototypes. The automated design system QCADdesigner version 2.0.3 synthesizes nanocircuits of full adders and models time diagrams of their performance. The energy of synchronous signals and consumption does not exceed 3,8 ´10-22 J. The results of simulation of single-electron nanoadders confirmed their advantages over the schemes of other developers in all operational parameters and characteristics and stimulate their further development for greater bit rate and number of majority functions.
Extracurricular Management Increasing Understanding of the Holy Scriptures
Authors: Jailani Syahputra Siregar  , Mukti Abdul , Amiruddin Siahaan
Published: September 2024

This research aims to determine extracurricular management to increase understanding of the UPTD holy book. South Labuhanbatu Regency State Elementary School. Methodologically, this research is interactive qualitative research with data collection techniques through document study, interviews and observations. The findings of this study reveal that planning carried out by the South Labuhanbatu Regency Education Office through deliberations/meetings. Organizing is done by developing and delegating tasks professionally and proportionally. It is necessary to delegate tasks so that each element can understand the function of the main tasks and functions because they feel that they have been entrusted with the task so that extracurricular management does not become chaotic and everyone works according to the tasks entrusted. The implementation is carried out by the Regional Government, in this case the South Labuhanbatu Regency Education Service, by providing guidance, direction, advice and motivation. In this case, the leadership always provides good guidance to all related elements, provides positive direction, provides constructive advice, and motivates all related elements, especially school principals and teachers, in carrying out their duties to always be kind. Meanwhile, supervision is carried out by the Regional Government, in this case the South Labuhanbatu Regency Education Service, by monitoring, supervising and evaluating the plans that have been implemented. In this case, the leadership always monitors the implementation of deviant plans. Leaders always evaluate things that are considered not on track. Leaders at every level always go directly into the field to see directly the existing objects.
The Effectiveness of Problem-Based Learning Model Assisted by Augmented Reality Media on The Motivation and Learning Outcomes
Authors: Shiva Febrianto Devardo , Aeni Kurotul
Published: September 2024

Learning Pancasila Education using the conventional model has an impact on low motivation and student learning outcomes in elementary schools. This research aims to determine the effectiveness of the problem-based learning model assisted by augmented reality media reviewed from motivation and learning outcomes of Pancasila education. This research uses a quasi-experimental research method (Quasi-Experimental Design), while the research design used is NonequValent Control Group Design. Data collection was carried out using questionnaire instruments to determine student motivation and multiple choices tests to determine students' Pancasila Education learning outcomes. The research sample was grade 5/B, totaling 21 students as the experimental grade and grade 5/A, totaling 20 students as the control grade. Research data analysis uses difference tests and data effectiveness tests. Results of the difference test with the independent sample t test with a tcount value of 2.882 for learning motivation and 2.483 for learning outcomes. The results of the effectiveness test used a one sample t test with a tcount value of 4.501 for learning motivation and 4.493 learning outcomes. The research conclusion is that the Problem Based Learning (PBL) model assisted by augmented reality (AR) media is effective in terms of motivation and learning outcomes for Pancasila Education.
Optimization of Digital Media Utilization for Anti-Bullying Campaigns Among Generation Z
Authors: Rejekiningsih Triana , Sari Dewi Ika , Qodr Taufiq Subhanul , Ariana Yudi , Sumaryati Sri
Published: September 2024

Digital learning media based on applications are rarely found in anti-bullying education, yet the impact of using such learning tools cannot be underestimated. Therefore, this study aims to develop a digital learning media product based on an application to promote anti-bullying among Generation Z in junior high schools. This research adopts a Research and Development (R&D) approach using the ADDIE model, focusing on the process of producing application-based digital learning media suitable for educational purposes. The research subjects consist of media experts, content experts, and the director of the Children's Care Foundation (KAKAK) in Surakarta. Data collection techniques involved media validation questionnaires, which were then analyzed using percentages and described to provide an overview of the suitability level of this media. The research results show that the average validation results were 88%, while the average results from content were 87%. After validation, this digital media fall into the 'Very Good' qualification. Therefore, based on assessments from media experts, content experts, and the director of the KAKAK Foundation, it is concluded that this application-based digital learning media product is categorized as 'feasible' for use as an alternative learning medium in promoting anti-bullying in junior high schools. The existence of this media is evidently an innovative learning tool that enriches the process of anti-bullying education.
Analisis Perubahan Penggunaan Lahan Menggunakan Citra Sentinel-2 Di Kecamatan Percut Sei Tuan Tahun 2018 - 2022
Authors: Nuel Immanuel Sinabang , Klarita Dwijayanti Waruwu  , Adesiana Sihombing  , Adeline  , Eni Yuniastuti
Published: September 2024

Population growth is a major driver of land cover/use change in general as it leads to economic development, which in turn requires land availability for other land uses, including infrastructure, services, industry and settlements. Using the symbolism of remote sensing satellites to plan land use over large areas is one approach that can be taken. This study aims to analyze land use change in Percut Sei Tuan District, Deli Serdang Regency, North Sumatra in the 2018-2022 period using Sentinel-2 satellite imagery. The method used is visual interpretation of satellite images with the help of ArcGIS software and multi-temporal spatial data comparison analysis. The results showed that there were 8 land use classes, namely water bodies, forests, rice fields, plantations, developed land, open land, clouds, and shrubs. Significant land use change occurred in built-up land which increased by 627 hectares (from 34% to 37% of the total area), while forest area decreased by 521 hectares (from 8% to 5%). These changes indicate land conversion from forest areas and other productive lands to built-up areas, driven by population growth and infrastructure needs. This study concludes that regular monitoring of land use change is necessary to support spatial planning and sustainable land resource management.
Pengembangan Media Pembelajaran Berbasis Design Animaker pada Materi Pengetahuan Dasar Pemetaan, SMA/MA Kelas X
Authors: Ilzam Moch , Sri Astutik  , Era Iswara Pangastuti  , Elan Artono Nurdin  , Asyroful Mujib
Published: September 2024

The rapid and limitless development of information technology marks the era of technology and media. However, the constraint of instructional time often poses a challenge for teachers utilizing technology-based learning media. This research aims to develop and validate a geography learning media based on the Animaker application for high school students, particularly focusing on basic mapping concepts. Using the ADDIE model, the study was conducted at MAN 2 Jember during the academic year 2022/2023, targeting X IPS grade students. Data collection involved student needs surveys, validation of content and media by experts, and student feedback on the learning media. The study developed a video-based geography learning media using Animaker for SMA/MA students, involving a sample of 45 X IPS grade students. The analysis phase included administering student needs surveys, which indicated a majority requirement for learning media. The design of the Animaker application focused on layout, characters, and learning material presentation. Validation by media, content, and educational experts showed valid average scores across all evaluation aspects. Implementation in X IPS 3 and X IPS 4 classes yielded positive student responses, with average ratings of 4.28 for the large group and 4.38 for the small group. Evaluation indicated that the learning media was well-received by students, demonstrating readiness for broader application.
Hubungan Sistem Kepercayaan dan Jenis Pekerjaan dengan Tingkat Partisipasi Nelayan dalam Upacara Adat Sedekah Laut
Authors: Febria Nur Endah Putri  , Ahman Sya  , Cahyadi Setiawan
Published: September 2024

Sea alms are held as a form of community gratitude for the abundant sea products as well as gratitude for the safety provided by Allah SWT in carrying out activities as fishermen. The purpose of this study is to determine the level of belief of the fishing community in the sea alms ceremony, second is to determine the income level of fishermen in Gempolsewu Village, third is to determine the level of participation of fishermen in the sea alms ceremony in Gempolsewu Village and fourth is to determine the relationship of the belief system and type of work to the participation of fishermen in the sea alms ceremony in Gempolsewu Village, Rowosari District. This research utilizes mixed methods research and uses survey techniques for data collection. The results of this study state that the level of belief of the fishing community in the sea alms ceremony is in the high category, the income level of the fishing community is in the medium category, and for the level of fishermen's participation is in the high category. For the relationship between the belief system and type of work, there is no significant relationship between the two variables on the participation of fishermen in the sea alms ceremony in Gempolsewu Village, Rowosari District. The author recommends to further researchers to conduct further research on the relationship of other cultural elements of traditions in Indonesia.
Automated mapping of land cover type within international heterogenous landscapes using Sentinel-2 imagery with ancillary geospatial data
Authors: Lasko Kristofer , O’Neill Francis , Sava Elena
Published: September 2024

A near-global framework for automated training data generation and land cover classification using shallow machine learning with low-density time series imagery does not exist. This study presents a methodology to map nine-class, six-class, and five-class land cover using two dates of a Sentinel-2 granule across seven international sites. The approach uses a series of spectral, textural, and distance decision functions combined with modified ancillary layers to create binary masks from which to generate a balanced set of training data applied to a random forest classifier. For the land cover masks, stepwise threshold adjustments were applied to reflectance, spectral index values, and Euclidean distance layers, with 62 combinations evaluated. Global and regional adaptive thresholds were computed. An annual 95th and 5th percentile NDVI composite was used to provide temporal corrections to the decision functions, and these corrections were compared against the original model. The accuracy assessment found that the regional adaptive thresholds for both the two-date land cover and the temporally corrected land cover could accurately map land cover type within nine-class, six-class, and five-class schemes. Lastly, the five-class and six-class models were compared with a manually labeled deep learning model (Esri), where they performed with similar accuracies. The results highlight performance in line with an intensive deep learning approach, and reasonably accurate models created without a full annual time series of imagery.
The built environment of the US Air Force all-volunteer force : preliminary analysis of building trends
Authors: Morrison Dawn
Published: September 2024

July 1, 2023, marks the 50th anniversary of the beginning of the all-volunteer force (AVF). At this time, buildings, structures, and other elements of the US Air Force’s (USAF) built environment associated specifically with the AVF will be potentially eligible as historic resources under the National Historic Preservation Act (NHPA). The relationship between the AVF and the USAF built environment, however, has not yet been examined, and no historic contexts exist that provide guidance on how to identify and evaluate properties that may be associated with the built environment of the USAF AVF and offer recommendations on management of these properties to assist USAF installations in complying with the NHPA. As a result, it is unclear if, and to what extent, buildings, structures, and other elements associated specifically with the AVF exist that may require management under NHPA. The USAF desires to better understand the relationship between the AVF and the USAF built environment and has requested the Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL) conduct a built-environment analysis of existing USAF real property. This research is intended to support USAF decision-makers in determining if further research is warranted and how best to plan for managing AVF-related buildings, structures, and other built environment elements under NHPA. Results of this analysis indicate a relationship exists between the AVF and the USAF built environment; 42 built-environment feature types with construction rates higher than the overall average during the AVF period are identified.
Prospective Approaches for Artificial Intelligence Integration in Indian School Libraries
Authors:   Librarian, St. Xaviers CMI Public School Bhavnagar Gujarat 364002, R. Jadeja Devyaniba , A. Gohil Jaypalsinh ,   Assistant Professor, Department of Computer Application, Marwadi University, Rajkot, Gujarat 360003, India
Published: September 2024

School libraries play a crucial role in the educational ecosystem, offering a variety of resources and services that contribute significantly to students’ academic success, personal development, and lifelong learning.The integration of Artificial Intelligence (AI) in school libraries brings about several benefits and opportunities, enhancing the overall learning experience for students and streamlining library operations.Libraries are dynamic institutions, and their tools need to evolve to keep pace with technological advancements and changing user expectations. Regular assessments, feedback from users, and collaboration with the broader library community can help identify areas for improvement and guide the development of more effective library science tools.While libraries can function without incorporating AI, certain challenges and limitations may arise in the absence of AI technologies. In this paper, we focus on AI research in the field of library science is essential for leveraging technology to its fullest potential, improving efficiency, enhancing user experiences, and ensuring that libraries remain dynamic and relevant in the digital age. It allows libraries to adapt to changing user needs and technological advancements, ultimately contributing to the overall effectiveness and impact of library services.
Repair of mandrels of a continuous mill through the use of adapters
Authors: Zhuravleva E. V. , Lazko O. M. , Shashkov A. N. , Manyakin A. B.
Published: September 2024

The article describes the repair of mandrels used on a continuous type PQF mill by using adapters made from billets. The starting materials are the tailstocks that have been taken out of service.

The process of repairing the mandrels allows the mandrel to be used in further work until the final regrinding to the last size range of the mandrel diameter.

The technological process of repair begins with turning the surface of the mandrel to the required size, grinding the surface, the process of cutting off the rear part of the mandrel, including the threaded connection. After the tailstock part has been cut off, the tailstock section is replaced with a transition piece manufactured in‑house. The adapter is a part with a fine tapered thread on one side, which is intended for connection to the mandrel, and with an internal thread on the other side, which serves to connect the rear part of the mandrel to the tailstock.

The provided technology will reduce the cost of purchasing new replacement tools by increasing the life cycle of the mandrel, and will reduce the number of mandrels that have become unusable by restoring the tailstock part.
Algorithm for optimization of cold‑rolled pipe rolling routes
Authors: Pilipenko S. V.
Published: September 2024

The relevance of the work is justified by the need to refine the methodology for calculating cold rolling routes, associated with the expansion of factors that need to be taken into account in conducting such calculations. The aim of the work is to develop an algorithm for optimizing the routes of cold rolling of pipes using CRP and CRPR type mills, convenient for implementation in a software product. The paper analyzes the main parameters for optimizing the routes of cold rolling of pipes, factors limiting the field of optimal values of the geometric parameters of the billet‑pipe in each pass. Among the latter, the maximum possible reduction in the cross‑sectional area, the required reduction in the cross‑sectional area in the last pass, the requirement for the nature of the distribution of the reduction value in the cross‑sectional area, in the wall thickness and in the pipe diameter from pass to pass and other parameters are highlighted. The importance of minimizing the number of passes is noted. The main dependencies included in the method for calculating the deformation parameters of the cold rolling route using CRP and CRPR mills are analyzed and highlighted. An algorithm for calculating the route of cold rolling of pipes, with several iteration operations, has been developed. The proposed algorithm allows optimizing the rolling route of pipes made of any grades of steels and alloys, and allows optimizing most parameters, including those affecting the economic parameters of production. Depending on the grade of steel or alloy, some iteration operations can be excluded. The algorithm has been tested in the practice of calculating rolling routes for pipes made of carbon and stainless steels and alloys.
Multiphase Tectonic Processes in the Mesozoic and Formation of Early Regional Geomorphic Pattern in the Qilian Orogenic Belt, Northeastern Tibetan Plateau
Authors: Feng Changhuan , Zheng Wenjun , Zhang Yipeng , Shen Xiaoming , Wang Weitao
Published: September 2024

Conventional orogenic settings are largely confined to plate boundaries and their immediate vicinity. However, there is growing recognition that deformation of the continental lithosphere may extend for considerable distances away from active plate boundaries. The Mesozoic Qilian orogenic belt occupies a key position in East Asia and thus is important to consider when interpreting intracontinental deformation there. To determine when and how the North Qilian orogenic belt developed, multiple sets of samples collected from the Dahuang Mountain of the North Qilian orogenic belt were analyzed for apatite (U-Th)/He and zircon (U-Th)/He thermochronology. The results show that the study area experienced multiphase tectonic exhumation events that took place in the Early-Middle Triassic (250–235 Ma), Middle-Late Jurassic (170–150 Ma), and Early Cretaceous (130–110 Ma). This study reveals that the generation deformation and stress distribution in the Dahuang Mountain fold-fault system have the characteristics of temporal–spatial migration from N to S. Results indicate widespread, continuous exhumation and deposition in the Qilian Mountain due to multiplate interaction since the Mesozoic, persisting till at least late Miocene. Multiphase intracontinental deformation is driven by stresses at plate boundaries, with lithosphere serving as stress pathway.
ANÁLISIS DEL FLUJO TÉRMICO EN TUBERÍAS CON ENFRIAMIENTO ASIMÉTRICO MEDIANTE HEATT®
Authors: Alarcón García Mariano , Luna-Abad Juan Pedro , Seco-Nicolás Manuel
Published: September 2024

Los flujos térmicos en condiciones de contorno asimétrico son frecuentes en todo tipo de conducciones en condiciones reales, dando lugar a distribuciones de temperaturas también asimétricas en el seno del fluido. Ejemplos de esto en instalaciones frigoríficas serían conducciones de frigorífero defectuosamente aisladas a temperaturas negativas, con producción de hielo en una de sus caras, etc. En el presente trabajo se estudia la distribución de temperaturas en el seno de tuberías de líquidos de uso en instalaciones frigoríficas (frigorígenos, frigoríferos u otros productos) sometidas a condiciones térmicas asimétricas en condiciones de flujo laminar. Para ello se hace uso de la herramienta informática de libre uso HEATT®, basada en el Método de Simulación por Redes, que proporciona el mapa térmico en diferentes secciones de la tubería, lo que permite determinar la porción de tubería cuyas condiciones se alejan de las de operación.
OPTIMIZACIÓN EXPERIMENTAL DE PRESIONES DE TRABAJO DE UN CICLO DE AUTOCASCADA R600a/R1150 PARA APLICACIONES DE ULTRA-BAJA TEMPERATURA
Authors: Martinez-Angeles Manel , Nebot Andrés Laura , Calleja-Anta Daniel , Llopis Rodrigo
Published: September 2024

El sistema de autocascada es ampliamente utilizado en aplicaciones de refrigeración de ultra baja temperatura, especialmente para la preservación de muestras médicas y biológicas. Este ciclo funciona con una mezcla compuesta por refrigerantes con puntos normales de ebullición distantes los cuales se fraccionan en el ciclo y crean corrientes con diferentes composiciones. Una con mayor proporción del componente más volátil, dedicada a producir el efecto de enfriamiento. La segunda corriente condensa la primera utilizando un intercambiador de calor de cascada y permite a ésta alcanzar las temperaturas deseadas. Este estudio se centra en la optimización experimental de un ciclo con autocascada (ver Figura 1) que emplea la mezcla R-600a/R-1150 [70/30%] para mantener una temperatura establecida de -80ºC en el espacio refrigerado. La optimización consiste en un ajuste experimental de la presión mediante la modificación de las longitudes de los dos capilares (dispositivos de expansión) del sistema. Se emplea un método teórico-experimental para calcular el COP, la capacidad de enfriamiento y las incertidumbres. Estos resultados, junto con parámetros como el consumo de energía de la planta, el ciclo de trabajo del compresor y el flujo de masa, son factores clave en la selección final de la combinación de capilares.
LAS ALTERNANCIAS TÉRMICAS DURANTE LA CONSERVACIÓN FRIGORÍFICA MODIFICAN EL CONTENIDO DE COMPUESTOS BIOACTIVOS DE NARANJAS SANGUINA
Authors: Valverde Juan Miguel , Espinosa Alicia , Guirao Carrascosa Alberto , Díaz-Mula Huertas María , Martínez-Romero Domingo
Published: September 2024

La naranja sanguina (Citrus sinensis L. Osbeck) cv Sanguinelli forman parte de las variedades con pigmentación roja, tanto en piel como en pulpa, debido al contenido de antocianinas, si bien también mantienen una elevada concentración de carotenoides. Durante la maduración de la naranja en el árbol se produce la síntesis de antocianinas, las cuales dependen de factores genéticos, pero también se ven influenciados por condiciones climáticas, principalmente la temperatura. La bibliografía indica que una mayor diferencia de temperatura entre el día y la noche conduce a una mayor acumulación de antocianinas. El objetivo de este trabajo fue estudiar el efecto del almacenamiento de las naranjas sanguinas en ciclos de 24 horas a 2 ºC y a 20 ºC (24 h 2ºC+24 h 20ºC) y compararlo con una conservación control a 8 ºC, sobre el contenido de los compuestos bioactivos: polifenoles totales, antocianinas y carotenoides. Además, se estudiaron otros parámetros de calidad postcosecha como la pérdida de peso, la firmeza, los sólidos solubles totales, la acidez y el color. Se observó un cambio en la composición de los compuestos bioactivos, los polifenoles totales y las antocianinas aumentaron durante la conservación frigorífica, pero este aumento fue menor en las frutas almacenadas a baja temperatura. Sin embargo, la concentración de carotenoides se mantuvo más elevada en los frutos almacenada a 2 y 20 ºC. Por otro lado, las naranjas tratadas mostraron una mayor pérdida de peso y una reducción de la firmeza. Por tanto, es preciso optimizar los parámetros tiempo-temperatura de los ciclos para mejorar la composición de compuestos bioactivos y minimizar las pérdidas de peso y firmeza durante la conservación frigorífica.
EVOLUCIÓN DE LA TEXTURA DEL CAQUI ALMACENADO EN FRÍO A DOS TEMPERATURAS MEDIANTE IMAGEN HIPERESPECTRAL
Authors: Castillo Girones Salvador , Lopez Chulia Marina , Cubero Setgio , Munera Sandra , Rodriguez Alejandro , Gómez Sanchís Juan , Aleixos Nuria , Blasco Jose
Published: September 2024

Las alteraciones en la textura del caqui durante el almacenamiento pueden influir en la aceptación del consumidor. Por ello, este estudio utilizó imagen hiperespectral para predecir la firmeza de la pulpa y examinar los cambios espectrales de forma no destructiva. 1,750 caquis variedad ‘Rojo Brillante’ de almacenaron a 1 °C y 5 °C durante tres meses. Se adquirieron imágenes (420-1010 nm) de 250 frutas bajo cada condición en la cosecha y cada mes. Posteriormente, se midió con un texturómetro la curva de carga para romper la pulpa. Con ellas, las frutas se clasificaron en tres grupos (Duro, medio y blando) mediante K-Nearest Neighbours. Posteriormente, se extrajo el espectro medio de cada caqui y las muestras se dividieron aleatoriamente en conjunto de entrenamiento (70%) y prueba (30%). Se entrenaron tres modelos predictivos: Análisis Discriminante de Cuadrados Parciales (PLS-DA), Máquina de Vector Soporte (SVM) y XGBoost, que predijeron con precisión superior al 98%. Además, se observaron diferencias notables en los espectros, especialmente en la región del agua (970 nm) debido a la degradación celular, picos de clorofila (680 nm) y carotenoides (475 nm. Por lo tanto, la mejor temperatura para el almacenamiento de caquis fue de 1 °C.
ANALYSIS OF SUITABLE METHODOLOGIES FOR COMPRESSOR MASS FLOW RATE CORRECTION TO OTHER SUPERHEAT LEVELS AND REFRIGERANTS
Authors: Marchante Avellaneda Javier , Ossorio Rubén , Navarro Peris Emilio , Shrestha Som S.
Published: September 2024

This paper investigates the impact of suction conditions and refrigerant on scroll compressor mass flow rate by using calorimeter tests from AHRI-11 and AHRI-21 reports, published by AHRI's Low-GWP Alternative Refrigerants Evaluation program.
Two Copeland scroll compressors (20 and 51 cm3) have been analyzed including different suction conditions (SH = 11K, SH = 22K, Ti = 18ºC) and several refrigerants (R134a, R32, R410A, R404A, etc.). Previous studies have explored response surfaces for energy consumption and mass flow rate variables.
This study aims to expand the analysis by identifying the optimal approach to extrapolate mass flow rate from specific suction conditions to others SH or suction temperature levels and refrigerants. The current compressor characterization standard relies on the 1981 Dabiri correlation to correct compressor mass flow rate with suction conditions. Thus, this study aims to assess the adequacy of this correction and explore alternative correction methods for improved results.
Estudio de los procesos de cambio de fase de PCM encapsulado para el almacenamiento de energía solar térmica en la producción de ACS
Authors: Egea Alberto , Bianqui Cristina , García Alberto , Viedma Antonio , Pérez García José
Published: September 2024

Este estudio tiene como objetivo examinar los procesos de fusión de PCM encapsulado en una cápsula de forma cilíndrica, fabricada en acero inoxidable. Los encapsulados se emplean para almacenamiento de energía térmica para generación de ACS. Tiene un diámetro de 60 mm y una altura de 20 mm. El PCM elegido es la parafina RT35HC, que tiene un punto de fusión alrededor de 35 ºC. Se realizan experimentos en una cámara de ensayos térmicos, colocando la cápsula de forma vertical. La temperatura de dicha cámara se controla mediante un PID. Se lleva a cabo un análisis del campo de temperatura del PCM utilizando termopares. Se ha demostrado que los sensores son capaces de detectar la evolución gradual de la fase líquida del PCM y su acumulación en la parte superior de la cápsula debido a su menor densidad
ANÁLISIS FLUIDO-DINÁMICO DE UNA VITRINA AUTOSERVICIO
Authors: SOTO ARMENDARIZ RICARDO , Rodríguez Antonio , Araiz Miguel , Elosua Ibai , Astrain David
Published: September 2024

Mantener la comida en condiciones óptimas de conservación es importante para su calidad y seguridad alimentaria. En la última etapa de la cadena de suministro se almacena en muebles refrigerados y congelados en supermercados, cuyo consumo energético es una elevada parte de estos.Este estudio aplica la herramienta CFD sobre un mueble horizontal refrigerado abierto. Se emplean boundary conditions sobre los diferentes componentes y secciones del mueble que han permitido obtener un modelo computacional que predice de manera fiable el comportamiento cinético y térmico del mueble. Cumpliendo con el objetivo de entender la distribución de velocidades y temperatura en su interior.Además, se identifica que la fila de paquetes superior (por su elevada temperatura), la rejilla de impulsión (por su influencia en la cortina de aire) y el conducto de admisión (por las pérdidas de carga), son los puntos desfavorables del mueble, es decir, los más perjudiciales para su eficiencia energética. Nuestro modelo computacional permite, en estos puntos, llevar a cabo en un futuro estudios que obtengan mejoras y contribuir a la reducción del consumo energético de este.
Solar cooking intensive experiences in south of Iberian Peninsula and its importance in research planning
Authors: Ruivo Celestino , Macías-Fuentes Francisco Javier
Published: September 2024

The Southern part of the Iberian Peninsula has a great solar energy potential available for domestic and industrial scale applications. Despite this potential, solar cooking has not been widely adopted. Both authors are employed by universities, one as a teacher in the University of Algarve (Portugal) and other as a laboratory technician in the University of Huelva (Spain). They are each passionate about incorporating solar cooking in their daily lives. They both solar cookers frequently, and have advocated their use in their respective countries for many years.  They consider themselves “well contaminated with the solar cooking virus”. They entered the solar cooking world by making and using several types of solar cookers, most of which were low cost devices made from recycled materials, later working on some commercialized units. This extensive experience of solar cookers and on solar cooking has enabled them to develop and optimise different types of solar cookers, and test different cooking vessels.  By contrast, some published authors appear to have had little day to day experience of using solar cookers. Thus, the main goal of this study is to list some important aspects of the practical use and performance of solar cookers that the research community should investigate
LA BANDEJA DE PLÁSTICO ACTIVA CON ACEITES ESENCIALES ENCAPSULADOS MEJORA LA CALIDAD DE LOS ARÁNDANOS FRESCOS REFRIGERADOS
Authors: López Gómez Antonio , Navarro Martínez Alejandra , López Avilés Francisco José , Martínez Hernández Ginés Benito
Published: September 2024

La producción de arándanos (principalmente en la zona de Huelva) en España ha aumentado en la última década debido a las altas propiedades saludables de estos frutos azules. Sin embargo, la baja temperatura óptima para el almacenamiento postcosecha de los arándanos implica elevados costes energéticos durante su conservación y transporte. Sin embargo, los aceites esenciales vegetales (AE) utilizados como tratamientos poscosecha pueden preservar la calidad del producto, lo que puede permitir aumentar la temperatura de ajuste de las cámaras frigoríficas. El envasado activo con AE es una excelente alternativa a los ineficaces tratamientos de lavado con AE (baja solubilidad de los AE en agua, alta sensibilidad de las muestras a los daños mecánicos, eliminación de la capa cerosa natural antimicrobiana de los arándanos, etc.). Por lo tanto, estudiamos la calidad (firmeza, microbiana y sensorial) de los arándanos durante el almacenamiento refrigerado (4 ºC) hasta 7 días utilizando envases activos de AE (con una mezcla encapsulada de AE de carvacrol:AE de orégano:AE de canela, 70:10:20) o envases de plástico comerciales. Los arándanos envasados con envases activos mostraron un 20% más de firmeza que las muestras de control al séptimo día. La carga de levaduras de las muestras dentro del envase activo era 1,1 unidades logarítmicas inferior a la de las muestras de control al cabo de 7 días. En general, los envases activos preservaron mejor la calidad de los arándanos durante el almacenamiento en frío, lo que se correlacionó con las puntuaciones sensoriales de las muestras.
EVALUACIÓN DEL EYECTOR PARA REFRIGERACIÓN A TEMPERATURA ULTRA BAJA (-80 ºC) USANDO REFRIGERANTES NATURALES
Authors: Udroiu Cosmin Mihai , Mota Babiloni Adrián , Giménez Prades Pau , Barragán-Cervera Ángel , Navarro Esbrí Joaquín
Published: September 2024

La necesidad de refrigeración a ultra baja temperatura se ha intensificado en los últimos años tras la aparición de vacunas en respuesta a la pandemia de COVID-19. Las tecnologías actuales para este rango de temperaturas son pocas, con un rendimiento muy bajo y utilizando refrigerantes con un alto potencial de calentamiento atmosférico. Este artículo trata de estudiar la introducción del eyector en ciclos en cascada para la refrigeración a ultra baja temperatura (-80 ºC) y estudiar su implementación tanto en ambas etapas como en una, analizando su comportamiento y resultados. El estudio se lleva a cabo con los refrigerantes R290 en la etapa de alta temperatura y R170 en la etapa de baja temperatura, ya que estos son refrigerantes naturales con un potencial de calentamiento atmosférico muy bajo. Los resultados muestran que el eyector es un componente que provoca mejoras del 21 % en la eficiencia del ciclo cuando se coloca en ambas etapas. Además, emite menos de la mitad (-57.5 %) de CO2e en comparación con los ciclos actuales para este rango de temperaturas.
LOW-TEMPERATURE CALORIMETRIC CHARACTERIZATION OF DEEP EUTECTIC SOLVENTS WITH ADDED WATER
Authors: Molina-García Antonio Diego , Schneider-Teixeira Aline , Martínez-Bartolome Miguel Ángel , De Ancos Begoña
Published: September 2024

Deep eutectic solvents (DES) are combinations of hydrogen bonds donors and acceptors, characterized by significantly lower freezing temperatures than their components.  NADES (with natural, biologically compatible components) are becoming popular for a wide applications variety, for their wide solvent capacities, non-toxicity, biodegradability, and inexpensive components. Applications include new means for bioactive compounds extraction and enzymatic reactions, polymer solubilizing and a variety of physicochemical processes, including those taking place at low temperature. Four DES (β-alanine and DL-malic or citric acid (plus water) and choline chloride and ethylene glycol or glycerol) were investigated by differential scanning calorimetry (DSC) at low temperature. Pure DES behave completely reversibly, proof of physicochemical stability. Alanine-DES present glass transitions between -40 and -80°C. Meanwhile, choline-DES show no thermal events between 0° and -80°C.
Increasing water produce glass transitions in all DES at decreasing temperatures, and devitrifications and freezing events. Choline-DES show no effects up to 20% water. However, alanine-DES show strong water effects, possibly phase separation into different water populations. Calcium alginate-sucrose beads were used as structural model for diffusion systems. Beads were incubated in DES (20 min/20 hours) and their low-temperature properties characterized. Short incubation periods were enough to radically alter their thermal behavior.
HAPPENING: an efficient cascade heat pump system for multifamily buildings
Authors: Corrales Ciganda José Luis , Iturralde Iñarga Jon , Urkola Lekuona Irantzu , Carrera Martin Angel , Urra Mardaraz Iñigo
Published: September 2024

An innovative hybrid heat pump system is presented as a novel solution for multifamily building heating system retrofitting. This system is very efficient on the one hand thanks to its innovative configuration in cascade, minimum thermal losses and on the other hand, the maximization of local solar energy self-consumption due to decoupling generation and consumption and applying smart control strategies. It is aimed at facilitating retrofitting of existing heating systems in multifamily buildings, enabling an efficient decarbonization. Three variations of the system have been designed, installed, and tested in real buildings across Europe, within the H2020 project “HAPPENING”. The project is now under monitoring phase and the preliminary results are positive, demonstrating the high efficiency of the concept
FAN PARAMETER ANALYS OF HEAT PUMP AIR CONDITIONING SYSTEMS WITH DIFFERENT HEAT EXCHANGERS CONFIGURATIONS.
Authors: Gutiérrez Cruz Mario Alberto , Barceló Ruescas Francisco
Published: September 2024

The residential sector accounts for 27% of the EU's total energy consumption, and more than half is used for space conditioning, so improvements in this sector would contribute to achieving the sustainability goals set.
Heat pumps (HP) have been presented as a good solution, as they are systems capable of satisfying air-conditioning needs in a more efficient way than systems based on fossil fuels; moreover, the REPowerEU Communication established the objective of doubling the current HP deployment rate in the next years.
In this sense, designing and optimizing air conditioning systems is crucial. This study presents a method to determine the power and airflow parameters of a fan in a heat pump air conditioning system. The calculation is performed considering the pressure drop associated with the design of the heat exchangers using the IMST-ART simulation tool. This modeling aims to obtain simulations closer to the real behavior under different design conditions for the development of more efficient air conditioning systems
ANÁLISIS EXPERIMENTAL DE LA MEZCLA CO2/R1270 COMO ALTERNATIVA AL CO2 EN UNA INSTALACIÓN FRIGORÍFICA DE CO2 TRANSCRÍTICA.
Authors: Vidan Falomir Francisco , Larrondo Sancho Rafael , Sánchez García-Vacas Daniel , Cabello Lopez Ramon
Published: September 2024

Con la normativa F-Gas, el sector de la refrigeración ha evolucionado hacia refrigerantes naturales más respetuosos con el medioambiente, como el dióxido de carbono (CO2), esta combina propiedades de alta seguridad, alta disponibilidad y bajo coste. Sin embargo, tiene una temperatura crítica relativamente baja (~30,98 ºC), lo que conlleva configuraciones de ciclo complejas para mejorar el rendimiento de la instalación, especialmente en zonas con temperaturas ambiente superiores a 26 ºC. Dado que el coste de estas configuraciones es elevado y/o solamente aplicable en instalaciones con potencias superiores a 20 kW, la ponencia plantea mezclar el CO2 con el R1270 (propileno), para conseguir aumentar la temperatura crítica, y mejorar así las prestaciones de ciclo.
El presente trabajo analiza experimentalmente tres mezclas de CO2/R1270 (91/9 %, 94/6 % y 97/3 % en masa) en una instalación de CO2 transcrítica, con temperaturas de 20 ºC hasta 34 ºC de foco caliente. Los resultados obtenidos trabajando sobre unas condiciones de servicio de media temperatura (demanda a 0 ºC), demostraron mejoras en el COP de hasta el 12,18 % a 34 ºC con 94/6 % de concentración y -14.94 bar en la presión óptima de rechazo de calor.
TOWARDS CARBON-NEUTRAL FISH COLD STORAGE: A SUSTAINABLE APPROACH THROUGH RENEWABLE ENERGY
Authors: Garcia João , Semedo Arian
Published: September 2024

Preserving perishable foods, particularly fish, demands meticulous attention throughout the entire supply chain, from capture to consumption. The critical role of cold storage facilities in maintaining optimal conditions, encompassing temperature and humidity regulation, is indispensable. Nevertheless, these facilities pose a considerable challenge due to their substantial electrical energy consumption, which significantly contributes to operational costs. In addressing this challenge, the implementation of energy-efficient strategies, including the utilization of advanced equipment and real-time monitoring facilitated by automation technologies, becomes imperative. This research investigates an innovative integrated cold storage system situated in Tarrafal, Santiago, Cape Verde, which harmoniously incorporates wind, solar, and tidal energy sources. The primary objectives are to evaluate the energy efficiency, financial viability, and environmental impact across four distinct hypothesis. Hypothesis 1 entails the deployment of two R134a refrigeration units powered by the conventional public grid, while Hypothesis 2 adopts a transcritical CO2 system reliant on grid electricity, Hypothesis 3 integrates CO2 technology with autonomous renewable energy sources and Hypothesis 4 leverages CO2 for refrigeration coupled with seawater heat exchange and autonomous renewable energy generation. The research findings strongly favor Hypothesis 4, demonstrating emissions of 15880 kg CO2eq with an impressive 5-year return on investment. The autonomous electricity production associated with this hypothesis markedly reduces emissions by more than 90%. Despite an initial higher investment, Hypothesis 3 showcases financial viability, contributing significantly to long-term energy sustainability. The autonomous energy production in this scenario results in a noteworthy reduction of more than 600000 kgCO2 compared to conventional systems, underscoring the positive impact of integrating local renewable energy sources.
[ORAL] COMPARATIVA ENTRE EL CICLO DE COMPRESIÓN DE VAPOR SIMPLE Y CON ECONOMIZADOR EN EL RENDIMIENTO ESTACIONAL DE UNA BOMBA DE CALOR AIRE-AGUA
Authors: Ortega Ignacio , Sieres Atienza Jaime , Cerdeira Fernando , Santos José Manuel
Published: September 2024

Este articulo estudia una bomba de calor aire-agua que funciona siguiendo un ciclo de compresión de vapor e incluye un depósito de refrigerante que permite compensar los desbalances de carga de refrigerante derivados de la diferencia de volúmenes internos de los distintos componentes según su modo de funcionamiento. Estas variaciones en la distribución de la carga, así como las variaciones climáticas a las que están expuestas este tipo de máquinas, hacen que la utilización de un sistema con economizador en la que se realiza una inyección de vapor a una presión intermedia sea una alternativa real para la mejora de su rendimiento.
Se realiza por tanto una valoración del efecto que tiene la inyección intermedia de vapor en ensayos normalizados en modo invierno sobre una máquina comercial con R410A como refrigerante, compresor de velocidad variable y válvulas de expansión electrónicas. El uso de un depósito de refrigerante permite obtener un ciclo con dos expansiones, regulando así la presión intermedia a la que se realiza la inyección. El efecto de esta variable se compara con los resultados obtenidos en ensayos a las mismas condiciones, siguiendo un ciclo de compresión de vapor simple, comparando sus respectivos rendimientos estacionales (SCOP).
Influencia de las infiltraciones en la demanda de calefacción en una vivienda unifamiliar aislada
Authors: Vera Alves Ícaro César , Romero Rincón Manuel J. , Martínez Beltrán Pedro J.
Published: September 2024

La permeabilidad al aire de la envolvente térmica juega un papel importante en la caracterización de la demanda de energía y principalmente en las temporadas de frío. Actualmente se emplean ensayos normalizados a presiones de referencia siendo el más común el Blower Door Test a 50 Pa. No obstante, dicha presión no refleja las condiciones reales de uso de la vivienda la cual estará normalmente entre 0-10 Pa y es por ello por lo que se emplean modelos que tratan de simular las infiltraciones en condiciones reales. Actualmente los modelos más empleados son el modelo del factor-N, el modelo de LBL y el modelo de AIM-2. El objetivo de este trabajo se centra en comparar los resultados obtenidos por estos tres modelos en una vivienda real en la cual se realizó un ensayo Blower Door Test, para ello se empleó como herramienta de simulación TRNSYS y se modeló el edificio mediante el type56. Los resultados arrojaron una media de un 17% de influencia en la demanda de calefacción.
PRÁCTICA DOCENTE CON COLECTORES SOLARES FRESNEL PARA LA GENERACIÓN DIRECTA DE VAPOR
Authors: Cazorla-Marín Antonio , Payá-Herrero Jorge , López-Navarro Alejandro
Published: September 2024

En diferentes titulaciones de ingeniería los alumnos adquieren conocimientos de energía solar térmica, incluida energía solar de concentración, pero en pocas ocasiones tienen la oportunidad de ver y analizar en detalle una instalación de este tipo, en condiciones de operación reales. En este trabajo se presenta una práctica de laboratorio basada en una instalación solar térmica de concentración con colectores lineales Fresnel para generación directa de vapor. Durante la práctica, visitarán la instalación, conociendo los diferentes componentes y viéndola en funcionamiento (orientación de los espejos en tiempo real y producción de vapor). Tras esto, analizarán datos de días enteros de operación en un aula informática, siendo capaces de calcular la energía generada por la instalación, el rendimiento de los colectores y el rendimiento de toda la instalación.
Con esta práctica se pretende que los alumnos comprendan el funcionamiento de un tipo de instalación prometedora para producir calor para diferentes procesos en lugares donde no hay acceso a otro tipo de combustibles o como alternativa para descarbonizar el sector industrial, cumpliendo con los Objetivos de Desarrollo Sostenible 1 (Fin de la pobreza), 4 (Educación de calidad), 7 (Energía asequible y no contaminante) y 9 (Industria, innovación e infraestructura).