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  • 1
    Publication Date: 2019
    Description: This paper proposes a new on-site technique for the experimental characterization of small wind systems by emulating the behavior of a wind tunnel facility. Due to the high cost and complexity of these facilities, many manufacturers of small wind systems do not have a well knowledge of the characteristic λ - C p curve of their turbines. Therefore, power electronics converters connected to the wind generator are usually programmed with speed/power control curves that do not optimize the power generation. The characteristic λ - C p curves obtained through the proposed method will help manufacturers to obtain optimized speed/power control curves. In addition, a low cost small wind emulator has been designed. Programmed with the experimental λ - C p curve, it can validate, improve, and develop new control algorithms to maximize the energy generation. The emulator is completed with a new graphic user interface that monitors in real time both the value of the λ - C p coordinate and the operating point on the 3D working surface generated with the characteristic λ - C p curve obtained from the real small wind system. The proposed method has been applied to a small wind turbine commercial model. The experimental results demonstrate that the point of operation obtained with the emulator is always located on the 3D surface, at the same coordinates (rotor speed/wind speed/power) as the ones obtained experimentally, validating the designed emulator.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 2
    Publication Date: 2019
    Description: The purpose of this paper is to explore the presence of spatial and temporal effects on the calls for noise disturbance service reported to the Local Police of València (Spain) in the time period from 2014 to 2015, and investigate how some socio-demographic and environmental variables affect the noise phenomenon. The analysis is performed at the level of València’s boroughs. It has been carried out using a logistic model after dichotomization of the noise incidence variable. The spatial effects consider first- and second-order neighbors. The temporal effects are included in the model by means of one- and two-week temporal lags. Our model confirms the presence of strong spatio-temporal effects. We also find significant associations between noise incidence and specific age groups, socio-economic status, land uses, and recreational activities, among other variables. The results suggest that there is a problem of "social" noise in València that is not exclusively a consequence of coexistence between local residents. External factors such as the increasing number of people on the streets during weekend nights or during summer months severely increase the chances of expecting a noise incident.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by MDPI
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  • 3
    Publication Date: 2019
    Description: One of the major consequences of the digital revolution has been the increase in the use of electronic devices in health services. Despite their remarkable advantages, though, the use of computers and other visual display terminals for a prolonged time may have negative effects on vision, leading to a greater risk of Computer Vision Syndrome (CVS) among their users. In this study, the importance of ocular and visual symptoms related to CVS was evaluated, and the factors associated with CVS were studied, with the help of an algorithm based on regression trees and genetic algorithms. The performance of this proposed model was also tested to check its ability to predict how prone a worker is to suffering from CVS. The findings of the present research confirm a high prevalence of CVS in healthcare workers, and associate CVS with a longer duration of occupation and higher daily computer usage.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI
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  • 4
    Publication Date: 2019
    Description: Latin American immigrants make up 49% of the total immigrant population in Spain, yet little is known about their eye health. The aim of this study is to determine if there are differences in self-perceived eye health, access to eye care specialists, and use of lenses between a sample of Latin American immigrant workers from Colombia and Ecuador, and native-born workers in Spain. We used data from the PELFI cohort (Project for Longitudinal Studies of Immigrant Families). The sample consisted of 179 immigrant workers born in Colombia or Ecuador, and 83 Spanish-born workers. The outcome variables were self-perceived eye health, access to eye specialists, and use of lenses. A descriptive analysis of the sample was carried out, and the prevalence of the three outcome variables in immigrants and natives was calculated and adjusted for explanatory variables. Random effects logistic regression models examined eye health outcomes by workers’ country of birth. Immigrants are less likely to report poor self-perceived eye health than native-born (ORc 0.46; CI 95%, 0.22–0.96). Furthermore, they have less access to specialists (ORc 2.61; CI 95%, 1.32–5.15) and a higher probability of needing lenses but not having them (ORc 14.14; CI 95%, 1.77–112.69). This latter variable remained statistically significant after adjusting for covariates (ORa 34.05; CI 95%, 1.59–729.04). Latin American immigrants may not value the use of lenses, despite eye care specialists indicating that they need them. Eye health education is required to recognize the importance of using lenses according to their visual needs.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by MDPI
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  • 5
    Publication Date: 2019
    Description: Satellite altimeters have been used to monitor river and reservoir water levels, from which water storage estimates can be derived. Inland water altimetry can, therefore, play an important role in continental water resource management. Traditionally, satellite altimeters were designed to monitor homogeneous surfaces such as oceans or ice sheets, resulting in poor performance over small inland water bodies due to the contribution from land contamination in the returned waveforms. The advent of synthetic aperture radar (SAR) altimetry (with its improved along-track spatial resolution) has enabled the measurement of inland water levels with a better accuracy and an increased spatial resolution. This study aimed to retrieve water levels from Level-1B Sentinel-3 data with focus on the minimization of the land contamination over small- to middle-sized water bodies (130 m to 4.5 km), where continuous clean waveforms rarely exist. Three specialized algorithms or retrackers, together with a new waveform portion selection method, were evaluated to minimize land contamination in the waveforms and to select the nadir return associated with the water body being overflown. The waveform portion selection method, with consideration of the Digital Elevation Model (DEM), was used to fit the multipeak waveforms that arise when overflying the continental water bodies, exploiting a subwaveform-based approach to pick up the one corresponding to the nadir. The performances of the proposed waveform portion selection method with three retrackers, namely, the threshold retracker, Offset Center of Gravity (OCOG) retracker and two-step SAR physical-based retracker, were compared. No significant difference was found in the results of the three retrackers. However, waveform portion selection using DEM information great improved the results. Time series of water levels were retrieved for water bodies in the Ebro River basin (Spain). The results show good agreement with in situ measurements from the Ebro Reservoir (approximately 1.8 km wide) and Ribarroja Reservoir (approximately 400 m wide), with unbiased root-mean-square errors (RMSEs) down to 0.28 m and 0.16 m, respectively, depending on the retracker.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by MDPI
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  • 6
    Publication Date: 2019
    Description: A third of the food produced in the world ends up in the rubbish, enough to put an end to world hunger. On the other hand, society is increasingly concerned to bring healthy eating habits. A RFID (radio frequency identification) food management system is designed to palliate the previously described issues in an Internet of Things (IoT) network paradigm. It consists of RFID readers placed on a user’s kitchen furniture, which automatically reads food information. There is no need for direct sight between reader and tag, as it occurs through the barcode technology. As a complement, a multi-platform web application is developed, allowing its users to check the date of food expiration and other detailed information. The application notifies the user when a product is about to expire. It also offers recipes that might be prepared with available foods, thus preventing them from being wasted. The recipes are accompanied by their nutritional information, so that the user can exhaustively monitor what he/she eats. This embedded system may provide economic benefits to the manufacturer, since it allows supermarkets to pay for displaying their products advertised through the application. After system deployment, design conclusions are shown, and future improvement points are indicated.
    Electronic ISSN: 1999-5903
    Topics: Computer Science
    Published by MDPI
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  • 7
    Publication Date: 2019
    Description: This article presents an analysis of the state of the art on the relationship between tourism, sustainability and competitiveness (TSC); moreover, the analysis also includes a focus on tourism destination (TSCD). To that end, information on the publications in these fields from recent years was sourced from the Web of Science database. In addition, the VOSviewer software program was used to enable a more in-depth bibliometric study, allowing the results to be clustered by authors, institutions, countries, and journals. The study carried out revealed that 808 articles have been published on aspects relating to TCS and 409 regarding TSCD. The results obtained underscore the greater scientific output on aspects related to sustainability than on aspects related to competitiveness and also that there has been a significant and exponential increase in both cases in recent years. These three fields of study (tourism, sustainability and competitiveness) are rarely combined in the literature, highlighting the lack of a comprehensive overview of this trinity. The evidence reported here suggest that the trend identified represents a future line of work for the coming years.
    Electronic ISSN: 2071-1050
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 8
    Publication Date: 2019
    Description: This retrospective study evaluates the effect of a telemedicine program developed in the central Catalan region in lowering the environmental footprint by reducing the emission of atmospheric pollutants, thanks to a reduction in the number of hospital visits involving journeys by road. Between January 2018 and June 2019, a total of 12,322 referrals were made to telemedicine services in the primary care centers, avoiding a total of 9034 face-to-face visits. In total, the distance saved was 192,682 km, with a total travel time saving of 3779 h and a total fuel reduction of 11,754 L with an associated cost of €15,664. This represents an average reduction of 3248.3 g of carbon dioxide, 4.05 g of carbon monoxide, 4.86 g of nitric oxide and 3.2 g of sulphur dioxide. This study confirms that telemedicine reduces the environmental impact of atmospheric pollutants emitted by vehicles by reducing the number of journeys made for face-to-face visits, and thus contributing to environmental sustainability.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by MDPI
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