Suchergebnisse

A current trend in the evolution of mobile communication networks consists in integrating Non-Terrestrial Networks (NTN) with the Terrestrial ones. One option to implement the NTN part of this hybrid architecture using Unmanned Aerial Vehicles (UAV) that relay the uplink radio signals through optical wireless backhaul links. A good choice for the radio uplink waveform is conventional SC-FDMA, which mitigates the PAPR and enables a longer battery lifetime at the transmitter side. For the optical backhaul link, which is based on low-cost Visible Light Communication (VLC) technology, a non-orthogonal implementation of SC-FDMA is proposed. By doing so, it is possible to improve the end-to-end throughput by reducing the communication bandwidth (to make it fit the LED frequency response), mitigate the effect of light reflections, and increase the energy efficiency in the backhaul link. Since VLC relies on non-coherent IM/DD, the non-orthogonal SC-FDMA waveform must rotate the phase of the IDFT subcarriers, in order to obtain real-valued signal samples at the output. Two strategies for relaying the data in the UAV node are evaluated, namely: Detect-and-Forward and Decode-and-Forward. The first one recovers the modulation part (i.e. partial regeneration), whereas the second one regenerates the transmitted message up to the bit level (i.e., total regeneration). This paper studies the combination of relaying strategy and NB-IoT Modulation and Coding Scheme (MCS) that maximizes the end-to-end throughput at different UAV altitudes. ; Grant numbers : TERESA - Hybrid TERrEstrial/Satellite Air Interface for 5G and Beyond (TEC2017-90093-C3-1-R) and from the Catalan Government under grants 2017-SGR-891 and 2017-SGR-1479 projects.

[EN] This paper presents a study on the flexural behavior of Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC) beams, which included conventional reinforcing bars. The study focuses on critical design aspects, such as concrete shrinkage and cracking implications on the tension-stiffening phenomenon. An experimental program with two different sized flexural reinforced UHPFRC beams was run. Beams were cast and tested in a four-point bending test (4PBT) using UHPFRC with different amounts of fibers: 130 and 160 kg/m(3) (1.66% and 2.00% in vol.) to cover a wide range of strain-softening and strain-hardening constitutive UHPFRC behaviors. A nonlinear finite element model (NLFEM) was developed to validate the mechanical tensile characterization of UHPFRC when applied to reinforced elements. Both shrinkage and tension-stiffening effects were considered to improve the model. After the NLFEM simulation, very reliable results were obtained at both the service and ultimate load levels compared to the experimental ones. Finally, some aspects about the design of reinforced UHPFRC cross-sections under bending forces are addressed and satisfactorily compared to the experimental results. ; This work forms part of Project "BIA2016-78460-C3-1-R" supported by the State Research Agency of Spain and the project "Rethinking coastal defence and Green-energy Service infrastructures through enHancEd-durAbiLity high-performance cement-based materials-ReSHEALience", funded by the European Union Horizon 2020 research and innovation programme under GA No 760824. ; Mezquida-Alcaraz, EJ.; Navarro-Gregori, J.; Martí Vargas, JR.; Serna Ros, P. (2021). Effects of tension stiffening and shrinkage on the flexural behavior of reinforced UHPFRC beams. Case Studies in Construction Materials. 15:1-28. https://doi.org/10.1016/j.cscm.2021.e00746 ; S ; 1 ; 28 ; 15

Las monarquías árabes del golfo Pérsico ocupan una posición preferente en la política exterior de España, debido a su importancia política y económica. La Transición y los primeros Gobiernos democráticos supusieron una profunda renovación de las relaciones internacionales españolas, repercutiendo en la forma de interactuar con las distintas regiones del mundo, incluyendo los regímenes de Oriente Próximo. En el período entre 1976-1996, los ejecutivos de Adolfo Suárez y Felipe González pusieron especial interés en fortalecer vínculos con Arabia Saudí, Omán, Emiratos Árabes Unidos, Qatar, Bahréin y Kuwait, constituyendo unas bilateralidades muy estrechas que se han mantenido durante más de cuarenta años. El conjunto de los seis países sigue teniendo una importancia vital para los intereses y objetivos españoles. ; The Arab monarchies of the Persian Gulf enjoy a preferential position in Spain's foreign policy, due to their political and economic relevance. The Transición period and the first democratic governments involved a profound renewal of Spanish international relations, involving ways of interacting with the different regions worldwide, the Middle East regimes included. In 1976-1996, both Adolfo Suárez and Felipe González focused on strengthening bonds with Saudi Arabia, Oman, United Arab Emirates, Qatar, Bahrain and Kuwait. They established narrow relationships that have been kept up for more than forty years. All those countries still represent an area of vital importance for Spanish interests and objectives. ; Este artículo es resultado de investigaciones realizadas dentro del proyecto: «Crisis y procesos de cambio regional en el norte de África. sus implicaciones para España» (CSO2017-84949-C3-3-P) financiados por el Ministerio de Economía, Industria y Competitividad (MINECO), la Agencia Estatal de Investigación (AEI) y el Fondo Europeo de Desarrollo Regional (FEDER).

Soil microclimate is a potentially important regulator of the composition of plant‐associated fungal communities in climates with significant drought periods. Here, we investigated the spatio‐temporal dynamics of soil fungal communities in a Mediterranean Pinus pinaster forest in relation to soil moisture and temperature. Fungal communities in 336 soil samples collected monthly over 1 year from 28 long‐term experimental plots were assessed by PacBio sequencing of ITS2 amplicons. Total fungal biomass was estimated by analysing ergosterol. Community changes were analysed in the context of functional traits. Soil fungal biomass was lowest during summer and late winter and highest during autumn, concurrent with a greater relative abundance of mycorrhizal species. Intra‐annual spatio‐temporal changes in community composition correlated significantly with soil moisture and temperature. Mycorrhizal fungi were less affected by summer drought than free‐living fungi. In particular, mycorrhizal species of the short‐distance exploration type increased in relative abundance under dry conditions, whereas species of the long‐distance exploration type were more abundant under wetter conditions. Our observations demonstrate a potential for compositional and functional shifts in fungal communities in response to changing climatic conditions. Free‐living fungi and mycorrhizal species with extensive mycelia may be negatively affected by increasing drought periods in Mediterranean forest ecosystems. ; This work was supported by the Spanish Ministry of Economy and Competitivity (MINECO) (grant number AGL2015‐66001‐C3). C.C. received support from the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya through the program of Doctorats Industrials, funded by the European Union and the European Social Fund. J.G.A. was supported by Juan de la Cierva (Grant number IJCI‐2014‐21393) and Ramon y Cajal fellowships (RYC‐2016‐20528) and J.A.B. benefits from the Serra‐Hunter Fellowship.

Car accidents are one of the top ten causes of death and are produced mainly by driver distractions. ADAS (Advanced Driver Assistance Systems) can warn the driver of dangerous scenarios, improving road safety, and reducing the number of traffic accidents. However, having a system that is continuously sounding alarms can be overwhelming or confusing or both, and can be counterproductive. Using the driver"s attention to build an efficient ADAS is the main contribution of this work. To obtain this 'attention value" the use of a Gaze tracking is proposed. Driver"s gaze direction is a crucial factor in understanding fatal distractions, as well as discerning when it is necessary to warn the driver about risks on the road. In this paper, a real-time gaze tracking system is proposed as part of the development of an ADAS that obtains and communicates the driver"s gaze information. The developed ADAS uses gaze information to determine if the drivers are looking to the road with their full attention. This work gives a step ahead in the ADAS based on the driver, building an ADAS that warns the driver only in case of distraction. The gaze tracking system was implemented as a model-based system using a Kinect v2.0 sensor and was adjusted on a set-up environment and tested on a suitable-features driving simulation environment. The average obtained results are promising, having hit ratios between 96.37% and 81.84% ; This work has been supported by the Spanish Government under projects TRA2016-78886-C3-1-R, PID2019-104793RB-C31, RTI2018-096036-B-C22, PEAVAUTO-CM-UC3M and by the Region of Madrid Excellence Program (EPUC3M17)

: The exponential evolution of technology and the growth of the elderly population are two phenomena that will inevitably interact with increasing frequency in the future. This paper analyses scientific literature as a means of furthering progress in sustainable technology for senior living. We carried out a bibliometric analysis of papers published in this area and compiled by the Web of Science (WOS) and Scopus, examining the main participants and advances in the field from 2000 to the first quarter of 2021. The study describes some interesting research projects addressing three different aspects of older adults' daily lives—health, daily activities and wellbeing—and policies to promote healthy aging and improve the sustainability of the healthcare system. It also looks at lines of research into transversal characteristics of technology. Our analysis showed that publications mentioning sustainability technologies for older adults have been growing progressively since the 2000s, but that the big increase in the number of research works in this area took place during the period 2016–2021. These more recent works show a tendency to study those factors that improve healthy aging, ensure the social inclusion of the elderly through technology and prolong the time in which they can live independent lives thanks to smart environments. Current research gaps in the literature are also discussed. ; : This work was funded by the Spanish Ministry of Economy, Industry and Competitiveness, (CSO2017-86747-R) and supported in part by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación, through the Smartlet and H2O Learn Projects under Grants TIN2017-85179-C3-1-R and PID2020-112584RB-C31, and in part by the Madrid Regional Government through the e-Madrid-CM Project under Grant S2018/TCS-4307.

Nowadays, the automatic text summarization is a highly relevant task in many contexts. In particular, query-focused summarization consists of generating a summary from one or multiple documents according to a query given by the user. Additionally, sentiment analysis and opinion mining analyze the polarity of the opinions contained in texts. These two issues are integrated in an approach to produce an opinionated summary according to the user's query. Thereby, the query-focused sentiment-oriented extractive multi-document text summarization problem entails the optimization of different criteria, specifically, query relevance, redundancy reduction, and sentiment relevance. An adaptation of the metaheuristic population-based crow search algorithm has been designed, implemented, and tested to solve this multi-objective problem. Experiments have been carried out by using datasets from the Text Analysis Conference (TAC) datasets. Recall-Oriented Understudy for Gisting Evaluation (ROUGE) metrics and the Pearson correlation coefficient have been used for the performance assessment. The results have reported that the proposed approach outperforms the existing methods in the scientific literature, with a percentage improvement of 75.5% for ROUGE-1 score and 441.3% for ROUGE-2 score. It also has been obtained a Pearson correlation coefficient of +0.841, reporting a strong linear positive correlation between the sentiment scores of the generated summaries and the sentiment scores of the queries of the topics. ; Work supported by Ministerio de Ciencia, Innovación y Universidades - Spain and Agencia Estatal de Investigación - Spain (Projects PID2019-107299GB-I00/AEI/10.13039/501100011033 and MTM2017-86875-C3-2-R), Junta de Extremadura - Spain (Projects GR18090 and GR18108), and European Union (European Regional Development Fund). Jesus M. Sanchez-Gomez is supported by Junta de Extremadura, Spain and European Union. (European Social Fund) under the doctoral fellowship PD18057. ; peerReviewed

GECEM Project (ERC-Starting Grant), ref. 679371, under the European Union's Horizon 2020 Research and Innovation Programme, www.gecem.eu. ; https://www.taylorfrancis.com/chapters/oa-edit/10.4324/9781003168058-18/goods-commodities-spanish-america-bartolom%C3%A9-yun-casalilla?context=ubx&refId=66fbcbb0-1b2e-4236-b63a-2e9eba872783 ; www.gecem.eu ; https://www.gecem.eu/publications/index.html ; This chapter shows that the introduction of Eurasian and African products in Latin America should be understood as one more phase in a longer wave of globalization across Eurasia, which had one of its pillars in the so-called medieval Islamic green revolution, of which Iberia was a cross-roads. Contrary to the model of ecological imperialism established by Crosby, the idea is defended that American globalization also meant the rise of very dynamic and hybrid ecosystems that would produce a new equilibrium and economic growth. The result is a more nuanced and constructive conception of ecological imperialism, which implied, on the other hand, a qualitative leap in the history of humanity that made America the main stage and the laboratory for the long-run development of unsustainable forms of exploitation. The complex mechanisms of diffusion and rejection of those products are also studied to underline how violence is inseparable from commerce or persuasion, as well as to what extent they are linked to deep social structural changes. The outcome is a path to consumerism that differs from the models normally used to understand what happened in Europe and a proposal to understand the history of consumption as inextricably associated with ecological history. ; GECEM Project (ERC-Starting Grant), ref. 679371, Horizon 2020, project hosted at UPO ; GECEM Project (ERC-Starting Grant), ref. 679371, Horizon 2020, project hosted at UPO

We explore alternative descriptions of the charged lepton sector in modular invariant models of lepton masses and mixing angles. In addition to the modulus, the symmetry breaking sector of our models includes ordinary flavons. Neutrino mass terms depend only on the modulus and are tailored to minimize the number of free parameters. The charged lepton Yukawa couplings rely upon the flavons alone. We build modular invariant models at levels 4 and 5, where neutrino masses are described both in terms of the Weinberg operator or through a type I seesaw mechanism. At level 4, our models reproduce the hierarchy among electron, muon and tau masses by letting the weights play the role of Froggatt-Nielsen charges. At level 5, our setup allows the treatment of left and right handed charged leptons on the same footing. We have optimized the free parameters of our models in order to match the experimental data, obtaining a good degree of compatibility and predictions for the absolute neutrino masses and the CP violating phases. At a more fundamental level, the whole lepton sector could be correctly described by the simultaneous presence of several moduli. Our examples are meant to make a first step in this direction. ; This project has received support in part by the MIUR-PRIN project 2015P5SBHT 003 \Search for the Fundamental Laws and Constituents" and by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement Nº 674896 and 690575. The research of F. F. was supported in part by the INFN. The research of J. C. C. was supported by the Spanish MINECO project FPA2016-78220-C3- 1-P, the Junta de Andalucía grant FQM101 and the Spanish MECD grant FPU14.

In this work a comparative study on phytochemical profiles of comfrey root extracts obtained by different extraction approaches has been carried out. Chemical profiles of extracts obtained by supercritical fluid (SFE), pressurized liquid (PLE), and conventional solid/liquid extraction were compared and discussed. Phytochemical composition was assessed by high-performance liquid chromatography coupled with electrospray time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS) identifying 39 compounds reported for the first time in comfrey root, mainly phenolic acids and fatty acids. The influence of different extraction parameters on phytochemical profiles of S. offcinale root was investigated for all applied techniques. PLE and maceration, using alcohol-based solvents (aqueous methanol or ethanol), were shown to be more effcient in the recovery of more polar compounds. Greater numbers of phenolics were best extracted by PLE using 85% EtOH at 63 ºC. The use of SFE and 100% acetone for 30 min enabled good recoveries of nonpolar compounds. SFE using 15% EtOH as a cosolvent at 150 bar produced the best recoveries of a significant number of fatty acids. The main compositional differences between extracts obtained by different extraction techniques were assigned to the solvent type. Hence, these results provided comprehensive approaches for treating comfrey root enriched in different phytochemicals, thereby enhancing its bioaccessibility. ; This work was funded by the project financially supported by the Serbian Ministry of Education, Science and Technological Development (TR 31014), the Andalusian Regional Government Council of Innovation and Science (P11-CTS-7625), the Spanish Ministry of Economy and Competitiveness (MINECO) (AGL2015-67995-C3-2, IJCI-2015-26789, and PTQ-13-06429), and the European Social Fund (FSE) (PTQ-13-06429).

There is an increasing need to control light phase with tailored precision via simple means in both fundamental science and industry. One of the best candidates to achieve this goal are electro-optical materials. In this work, a novel technique to modulate the spatial phase profile of a propagating light beam by means of liquid crystals (LC), electro-optically addressed by indium-tin oxide (ITO) grating microstructures, is proposed and experimentally demonstrated. A planar LC cell is assembled between two perpendicularly placed ITO gratings based on microstructured electrodes. By properly selecting only four voltage sources, we modulate the LC-induced phase profile such that non-diffractive Bessel beams, laser stretching, beam steering, and 2D tunable diffraction gratings are generated. In such a way, the proposed LC-tunable component performs as an all-in-one device with unprecedented characteristics and multiple functionalities. The operation voltages are very low and the aperture is large. Moreover, the device operates with a very simple voltage control scheme and it is lightweight and compact. Apart from the demonstrated functionalities, the proposed technique could open further venues of research in optical phase spatial modulation formats based on electro-optical materials. ; This work was supported by the Comunidad de Madrid and FEDER Program (S2018/NMT-4326), the Ministerio de Economía y Competitividad of Spain (TEC2016-77242-C3-1-R and TEC2016-76021-C2-2-R), the FEDER/Ministerio de Ciencia, Innovación y Universidades and Agencia Estatal de Investigación (RTC2017-6321-1, PID2019-109072RB-C31 and PID2019-107270RB-C21). The authors also acknowledge the support by the Ministry of National Defense of Poland (GBMON/13-995/2018/WAT), Military University of Technology (Grant no. 23-895).

This article belongs to the Special Issue Smart Learning ; In education, several studies have tried to track student persistence (i.e., students' ability to keep on working on the assigned tasks) using di fferent definitions and self-reported data. However, self-reported metrics may be limited, and currently, online courses allow collecting many low-level events to analyze student behaviors based on logs and using learning analytics. These analyses can be used to provide personalized and adaptative feedback in Smart Learning Environments. In this line, this work proposes the analysis and measurement of two types of persistence based on students' interactions in online courses: (1) local persistence (based on the attempts used to solve an exercise when the student answers it incorrectly), and (2) global persistence (based on overall course activity/completion). Results show that there are different students' profiles based on local persistence, although medium local persistence stands out. Moreover, local persistence is highly a ffected by course context and it can vary throughout the course. Furthermore, local persistence does not necessarily relate to global persistence or engagement with videos, although it is related to students' average grade. Finally, predictive analysis shows that local persistence is not a strong predictor of global persistence and performance, although it can add some value to the predictive models. ; This work was partially funded by FEDER/Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación/project Smartlet (TIN2017-85179-C3-1-R), and by the Madrid Regional Government, through the project e-Madrid-CM (S2018/TCS-4307). The latter is also co-financed by the Structural Funds (FSE and FEDER). This work received also partial support by Ministerio de Ciencia, Innovación y Universidades, under an FPU fellowship (FPU016/00526).

This work has been published in Solar Energy 198 (2020) 696–703 (DOI:10.1016/j.solener.2020.02.009). In this work, we report the effect of an ultra-thin Al2O3 layer (down to 3 nm) as interface passivation strategy for the improvement of the performance of Cu2ZnSnS4/CdS based solar cells. After an initial optimization, the Al2O3 deposited by thermal evaporation is proved to improve the properties of the p-n junction. The fabricated devices showed an increment in Voc depending on the composition of the absorber, and an improvement in fill factor (FF) apparently related to the insulation of possible shunt-paths. Also, the impact on other optoelectronic parameters is discussed. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 712949 (TECNIOspring PLUS) and the Government of Catalonia's Agency for Business Competitiveness (ACCIÓ). This research has also been supported by the H2020 Programme under the project INFINITE-CELL (H2020-MSCA-RISE-2017-777968), by the Spanish Ministry of Science, Innovation and Universities under the IGNITE project (ENE2017-87671-C3-1-R), and by the European Regional Development Funds (ERDF, FEDER Programa Competitivitat de Catalunya 2007–2013). Authors from IREC and the University of Barcelona belong to the SEMS (Solar Energy Materials and Systems) Consolidated Research Group of the "Generalitat de Catalunya" (Ref.2017 SGR 862). M.P. thanks the Government of Spain for the Ramon y Cajal Fellowship (RYC-2017-23758). This research was also supported by Consejo Nacional de Ciencia y Tecnología (CONACYT) with the scholarship No. 433146 and with the project CB-CONACYT-255062. Finally, this research was also supported by Programa de Fortalecimiento de la Calidad Educativa (PFCE 2019) and by Project VIEP 2019.

© 2020 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ ; The development of Urban-Scale Energy Modelling (USEM) at district or city level is today the goal of many research groups due to the increased interest in applications such as new strategies for city energy supply/demand, urban development planning, or distribution networks stability. It is believed that the assessment of the true potential for energy savings in a city can be done with computer simulation by considering a holistic analysis of the system. The goal of this paper is to provide a review of the existing USEM tools that aim at modelling the dynamic interaction among energy demand, generation and distribution in a city or district through the interaction of different sub-models. The main characteristics covered by the modelling tools are summarised in two matrices. The present study goes beyond other existing review studies by focusing on multi-domain USEM tools and emphasizing the distinction among the different architectures behind them. ; This work was supported by the research and innovation programme Horizon 2020 of the European Union under the Grant agreement no. 646456 (GrowSmarter); the GEIDI project (ref. TIN2016-78473-C3-3-R) financed by the Ministry of Economy and Competitiveness of Spain; and CC's work was supported by the Grant IJCI-2015-26650 (MICINN). ; Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant ; Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles ; Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant ; Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles ; Postprint (author's final draft)

It has been shown elsewhere that two spatially separated atoms can jointly absorb one photon, whose frequency is equal to the sum of the transition frequencies of the two atoms. We describe this process in the presence of an ensemble of many two-level atoms and show that it can be used to generate spin squeezing and entanglement. This resonant collective process allows us to create a sizable squeezing already at the single-photon limit. It represents a way to generate many-body spin-spin interactions, yielding a two-axis twisting-like interaction among the spins, which is very efficient for the generation of spin squeezing. We perform explicit calculations for ensembles of magnetic molecules coupled to a superconducting coplanar cavities. This system represents an attractive on-chip architecture for the realization of improved sensing. ; D.Z. acknowledges RIKEN for its hospitality and the support by the Spanish Ministerio de Ciencia, Innovaciòn y Universidades within Project No. MAT2017-88358-C3-1-R, the Aragòn Government Project Q-MAD, EU-QUANTERA Project SUMO, and the Fundaciòn BBVA. F.N. is supported in part by: NTT Research, Army Research Office (ARO) (Grant No. W911NF-18-1-0358), Japan Science and Technology Agency (JST) (via the Q-LEAP program, and the CREST Grant No. JPMJCR1676), Japan Society for the Promotion of Science (JSPS) (JSPS-RFBR Grant No. 17-52-50023, and JSPS-FWO Grant No. VS.059.18N), and the Grant No. FQXiIAF19-06 from the Foundational Questions Institute Fund (FQXi), a donor advised fund of the Silicon Valley Community Foundation. S.S. acknowledges the US Army Research Office (ARO) (Grant No. W911NF-19-1-0065). ; Peer reviewed