Thermal characterisation of compact heat exchangers for air heating and cooling in electric vehicles

[EN] The use of air conditioning in all-electric cars reduces their driving range by 33% in average. With the purpose of reducing the energy consumption of the vehicle and optimising the performance of the batteries, the mobile air-conditioning can be integrated with the temperature control system of the powertrain by means of a coolant loop. In such layouts, the air-to-coolant heat exchangers must operate efficiently in both air heating and cooling modes. Dynamic simulation tools comprising the entire thermal system are essential to assess its performance. In this context, fast but accurate models of the system components are required. This paper presents the thermal characterisation of a commercial compact louvered-fin flat-tube heat exchanger (heater core) for this novel application, based on an experimental campaign comprising 279 working points that reflect real air-conditioning (heating and cooling) working conditions. A general methodology to fit a single correlation of the global heat transfer coefficient for both dry and wet working conditions is explained. The semiempirical correlation developed is employed in a single-node model of the heat exchanger that requires minimal computation time. The present model predicts the heat transfer rate with an average deviation of 3.5% in the cases with dehumidification and 1.9% in the cases when the heat exchanger remains dry.This work has been supported by the European Commission under the 7th European Community framework program as part of the ICE project ‘‘MagnetoCaloric Refrigeration for Efficient Electric Air-Conditioning”, Grant Agreement no. 265434. B. Torregrosa-Jaime acknowledges the Spanish Education, Culture and Sport Ministry (Ministerio de Educación, Cultura y Deporte) for receiving the Research Fellowship FPU ref. AP2010-2160.Torregrosa-Jaime, B.; Corberán, JM.; Payá-Herrero, J.; Delamarche, JL. (2017). Thermal characterisation of compact heat exchangers for air heating and cooling in electric vehicles. Applied Thermal Engineering. 115:774-781. https://doi.org/10.1016/j.applthermaleng.2017.01.017S77478111

Assessment of acoustic reciprocity and conservativeness in exhaust aftertreatment systems

[EN] Tightening emission standards limiting gas and aerosol emissions from internal combustion engines have led to the extensive use of exhaust aftertreatment systems (EATS) with different chemical functions as a solution to meet standards requirements. Incidentally, the placement of aftertreatment monolithic devices into the exhaust line also plays a key role on the exhaust noise emission. Their presence disturbs the pattern of the pressure waves and sets the boundary conditions for the silencer design. The impact of the EATS on wave transmission can be analyzed by means of the transmission or scattering matrix. The present work discusses the implications of acoustic reciprocity and conservativeness on the definition of the scattering matrix elements. The fulfillment of these properties in real operating conditions was evaluated against a set of experimental data obtained for several exhaust aftertreatment monolithic bricks in an impulse test rig. The influence of different excitation amplitudes and superimposed mean flows was also considered. Once it was shown that the devices are reciprocal, the need to account for dissipation phenomena was evidenced. Finally, the application of reciprocity and conservativeness together with dissipation provided simple expressions allowing to predict the response of the EATS in the inverse direction, i.e. from outlet to inlet, from the transmission and reflection properties obtained in the direct direction. Thus, the proposed procedure becomes useful to reduce both the required number of tests and the gas dynamics modelling work in methodologies driven to assess the acoustic response of EATS based on the use of experimental and computational tools. (C) 2018 Elsevier Ltd. All rights reserved.This research has been partially supported by FEDER and the Government of Spain through project TRA2016-79185-R. Additionally, the Ph.D. student Enrique José Sanchis has been funded by a grant from Universitat Politècnica de València with reference FPI-2016-S2-1355.Torregrosa, AJ.; Piqueras, P.; Sanchis-Pacheco, EJ.; Guilain, S.; Dubarry, M. (2018). Assessment of acoustic reciprocity and conservativeness in exhaust aftertreatment systems. Journal of Sound and Vibration. 436:46-61. https://doi.org/10.1016/j.jsv.2018.08.032S466143

Exploitation and Processing of Online Information for Annotating and Generating Texts Adapted to the User

La gran cantidad de información disponible en Internet está dificultando cada vez más que los usuarios puedan digerir toda esa información, siendo actualmente casi impensable sin la ayuda de herramientas basadas en las Tecnologías del Lenguaje Humano (TLH), como pueden ser los recuperadores de información o resumidores automáticos. El interés de este proyecto emergente (y por tanto, su objetivo principal) viene motivado precisamente por la necesidad de definir y crear un marco tecnológico basado en TLH, capaz de procesar y anotar semánticamente la información, así como permitir la generación de información de forma automática, flexibilizando el tipo de información a presentar y adaptándola a las necesidades de los usuarios. En este artículo se proporciona una visión general de este proyecto, centrándonos en la arquitectura propuesta y el estado actual del mismo.The great amount of available online information is making increasingly more and more difficult that users can assimilate such as volume of information, being this almost inconceivable without using Human Language Technologies (HLT) tools, for instance, information retrieval systems or automatic summarisers. The interest of this emerging project (and therefore its main goal) is precisely motivated by the need to define and create a HLT-based technological framework, able to process and semantically annotate all this information, allowing also the automatic generation of information, and making the type of information to be presented more flexible by adapting it to the users' needs. This article provides an overview of this project, focusing on the proposed architecture and its current status.Este proyecto ha sido financiado por la Universidad de Alicante a través del proyecto emergente “Explotación y tratamiento de la información disponible en Internet para la anotación y generación de textos adaptados al usuario” (GRE13-15) y su temática se enmarca en el contexto de los proyectos “DIIM2.0: Desarrollo de técnicas Inteligentes e Interactivas de Minería y Generación de Información sobre la Web 2.0” (PROMETEOII/2014/001) financiado por la Generalitat Valenciana y el proyecto “Técnicas de Deconstrucción en la Tecnologías del Lenguaje Humano” (TIN2012-31224) financiado por Ministerio de Economía y Competitividad del Gobierno de España

Frecuencia del consumo de drogas legales: Diferencias de edad en la adolescencia

El consumo de drogas es especialmente relevante por sus efectos negativos sobre la salud psicofísica y el funcionamiento social de los jóvenes. El objetivo de este estudio fue analizar las diferencias de edad respecto a las frecuencias de consumo de alcohol y tabaco en una muestra de 354 escolares (50.85% varones) de 12 a 18 años (M = 14.66; DT = 1.08) que cumplimentaron el Questionnarie about Consume of Alcohol and Tobacco (TNT). Los resultados muestran que el 82.4% de los adolescentes ha consumido bebidas alcohólicas en alguna ocasión y el 25.6% es consumidor actualmente. Respecto al consumo de tabaco, el 40.4% de estudiantes afirma haber fumado en alguna ocasión, siendo consumidores actuales el 8.2%. Asimismo, se hallaron diferencias estadísticamente significativas entre la adolescencia temprana y tardía, observándose un aumento sustancial del consumo actual de ambas sustancias con la edad. Estos resultados resaltan la importancia de la variable edad a la hora de planificar medidas preventivas y de promoción de la salud en población adolescente

Relaxation in non-Markovian models: From static to dynamic heterogeneity

[EN] Glass transition processes have often been explained in terms of wide distributions of relaxation times. By means of a simple stochastic model we here show how dynamic heterogeneity is the key to the emergence of the glass transition. A non-Markovian model representing a small open region of the amorphous material was previously shown to reproduce the time and thermal characteristic behavior of supercooled liquids and glasses. Due to the interaction of the open regions with their environment, the temperature dependence of the equilibrium relaxation times differs from the featureless behavior of the relaxation times of closed regions, whose static disorder does not lead to a glass transition, even with wider distributions of equilibrium relaxation times. The dynamic heterogeneity of the open region produces a glass transition between two different regimes: a faster-thanArrhenius and non-diverging growth of the supercooled liquid relaxation times and an average Arrhenius behavior of the ideal glass. The Kovacs' expansion gap was studied by evaluating the nonequilibrium distribution of relaxation times after the temperature quenches.Funding for open access charge: CRUE-Universitat Polit`ecnica de Val`encia. RSS and JMM acknowledge the Spanish Ministry of Science, Innovations and Universities through the RTI2018-097862-B-C21 Project (including the FEDER financial support). CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER Actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.Torregrosa Cabanilles, C.; Molina Mateo, J.; Sabater I Serra, R.; Meseguer Dueñas, JM.; Gómez Ribelles, JL. (2022). Relaxation in non-Markovian models: From static to dynamic heterogeneity. Journal of Non-Crystalline Solids. 576. https://doi.org/10.1016/j.jnoncrysol.2021.12124512124557

Intelligent information processing to support decision-making

Proyecto emergente centrado en el tratamiento inteligente de información procedente de diversas fuentes tales como micro-blogs, blogs, foros, portales especializados, etc. La finalidad es generar conocimiento a partir de la información semántica recuperada. Como resultado se podrán determinar las necesidades de los usuarios o mejorar la reputación de diferentes organizaciones. En este artículo se describen los problemas abordados, la hipótesis de trabajo, las tareas a realizar y los objetivos parciales alcanzados.This project is focused on intelligent information processing using different sources such as micro-blogs, blogs, forums, specialized websites, etc. The goal is to obtain new knowledge using semantic information. As a result we can determine user requirements or improve organizations reputation. This paper describes the problems faced, working hypothesis, tasks proposed and goals currently achieved

Cen X–3 as seen by MAXI during six years

The aim of this work is to study both light curve and orbital phase spectroscopy of Cen X-3 taking advantage of the MAXI/GSC observation strategy. These studies allow delimiting the stellar wind properties and its interactions with the compact object. From the analysis of the light curve, we have estimated the orbital period of the binary system and also found possible QPOs around a superorbital period of Psuperorb = 220 ± 5 days. Both orbital phase-averaged and phase-resolved spectra were extracted and analysed in the 2.0{20.0 keV energy range. Two models have described spectra satisfactorily, a partial absorbed Comptonization of cool photons on hot electrons plus a power law, and a partial absorbed blackbody plus a power law, both modified by adding Gaussian lines. The high value of the X-ray luminosity in the averaged spectrum indicates that the accretion mode is not only due to the stellar wind.Se pretende estudiar la curva de luz y la espectroscopía en fase orbital de Cen X-3 gracias a la estrategia de observación de MAXI/GSC. Estos estudios permiten delimitar las propiedades del viento estelar y sus interacciones con el objeto compacto. Por medio de este análisis hemos estimado el período orbital del sistema y hemos encontrado posibles QPOs alrededor de un superperíodo orbital de Psuperorb = 220 ± 5 días. Hemos extraído y analizado los espectros medio y en fase orbital en el intervalo 2.0{20.0 keV por medio de dos modelos: una comptonización parcialmente absorbida de fotones fróos en electrones calientes más una ley de potencias y un cuerpo negro parcialmente absorbido más una ley de potencias, ambos modificados por líneas Gaussianas. El alto valor de la luminosidad del espectro medio indica un modo de acreción no debido solamente al viento estelar.This work was supported by the Spanish Ministry of Education and Science project number ESP2017-85691-P

Experimental investigation of the temperatures and performance of a commercial ice-storage tank

[EN] This paper presents the results of an experimental installation with an internal melt-ice-on-coil tank which has a total capacity of 172 kWh. The aim of this work is to analyse the freezing process in a tank with counter-current spiral-shaped coils immersed in around 1855l water. An experimental campaign has been performed with different inlet temperatures and mass flow rates of the heat transfer fluid. This study analyses (i) the chiller performance, (ii) the ice-formation process and (iii) the energy consumption of the installation. Supply temperatures between 2.5 C and 5.2 C have been sufficient to charge the tank without using any nucleating agents. The lowest energy consumption has been achieved for the fastest charging tests.The authors gratefully acknowledge ACCIONA Infraestructuras for the financing support and collaboration. Parts of the experimental results used in this work were collected at Federico II University during the project "Layout d'impianto e metodi di controllo innovativi per la refrigerazione domestica, commerciale e professionale". A.W. Mauro acknowledges the financial support provided by Regione Campania.López-Navarro, A.; Biosca Taronger, J.; Torregrosa-Jaime, B.; Martínez Galván, IO.; Corberán, JM.; Esteban-Matías, JC.; Payá-Herrero, J. (2012). Experimental investigation of the temperatures and performance of a commercial ice-storage tank. International Journal of Refrigeration. 36(4):1310-1318. doi:10.1016/j.ijrefrig.2012.09.008S1310131836

Análisis de Invarianza y Diferencias de Medias Latentes Entre Adolescentes Americanos, Españoles y Chinos Usando la Escala de Ansiedad Social para Adolescentes (SAS-A)

Background: Social anxiety is one of the most prevalent disorders among adolescents (Stein et al., 2017). The main aim of this study was to analyze the equivalence of scores on the Social Anxiety Scale for Adolescents (SAS-A) using structural equation modeling and identify differences in latent means of social anxiety in China, Spain, and the USA. Method: Random sampling was used to recruit participants, which included 536 Chinese (46% girls), 1,178 Spanish (55.3% girls) and 866 North American (55.1% girls) adolescents. The participants’ ages ranged between 14 and 17 years old. Results: The SAS-A three-factor correlated model of social anxiety remained invariant between the Spanish and North American adolescents, but results could not be replicated in the Chinese adolescents [M2 = ΔS-Bχ2 (Δdf, p) = 4732.56 (36, < .01)]. Analyses of latent differences between Spain and the USA showed that Spanish adolescents had higher scores than North Americans for Fear of Negative Evaluation (TS = -9.630; d = .44) and for Social Avoidance and General Anxiety towards people (TS = -2.717; d = .12). Conclusions: The results are interpreted according to the cultural traits of individualism-collectivism and self-construal, and practical implications are discussed.Antecedentes: la ansiedad social es uno de los trastornos con mayor prevalencia en adolescentes (Stein et al., 2017). Así, el propósito principal de este estudio fue analizar la invarianza de la Escala de Ansiedad Social para Adolescentes (SAS-A) mediante un modelo de ecuaciones estructurales y examinar las diferencias de medias latentes en ansiedad social en adolescentes de China, España y EE.UU. Método: los participantes se seleccionaron a través de muestreo aleatorio: 534 chinos (46% chicas), 1.178 españoles (55,3% chicas) y 866 norteamericanos (55,1% chicas), con edades comprendidas entre los 14 y 17 años. Resultados: las puntuaciones del modelo de tres factores correlacionados de ansiedad social de la SAS-A resultaron invariantes entre adolescentes españoles y norteamericanos, pero estos resultados no fueron replicados en adolescentes chinos [M2 = ΔS-Bχ2 (Δdf, p) = 4732.56 (36, < .01)]. El análisis de medias latentes entre España y EE.UU. mostró que los adolescentes españoles manifestaban niveles más altos de Miedo ante las evaluaciones negativas (TS = -9.630; d = .44) y Evitación social y ansiedad general hacia las personas (TS = -2.717; d = .12). Conclusiones: estos hallazgos fueron interpretados atendiendo al de individualismo-colectivismo y las concepciones culturales de la propia persona, analizando sus implicaciones prácticas