33 research outputs found

    Estimation of photovoltaic potential for electricity self-sufficiency: A study case of military facilities in northwest Spain

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    Renewable energies, including photovoltaic energy, are attracting widespread international attention, in reaction to worsening environmental problems and the diminishing long-term sustainability of fossil fuel energies. In this work, the potential benefits of installing photovoltaic panels on several buildings at the Spanish Naval Military School (Escuela Naval Militar, ENM) of Mar ın are considered. The two salient advantages are significant economic savings from the production and the sale of electricity to the Spanish Electricity Network and achieving selfsufficiency in electricity requirements. Consequently, the main objective of this work is to estimate the energy potential of photovoltaic installations on the roofs of the ENM buildings. This is the first time that a project of this nature and size is presented to the Spanish Navy. To that end, a three-dimensional geographic analysis of the buildings is performed using three freeware software: Trimble SketchUp, Skelion, and Photovoltaic Geographical Information System. An economic study is also conducted to determine the feasibility of the installations, by estimating the Net Present Value of the photovoltaic installation and the Internal Rate of Return associated with the project. Subsequently, a sensitivity analysis that considers the most important parameters for the calculation of the amortization period is reported. The results show that the installation could fulfill the ENM electrical demands and could, in addition, generate significant economic benefits. The conclusions end with a recommendation to consider the merits of the proposed solution.Regional Government of Castilla y Le on (Ref. BU034U16), under European Regional Development Fund, and the Spanish Ministry of Economy, Industry and Competitiveness under the IþD þ i state programme Challenges for the Society (Ref. ENE-2014-54601-R). One of the authors, David Gonz alez Pe~na, thanks Junta de Castilla-Le on for economic support (PIRTU Program, ORDEN EDU/301/2015

    Climas motivacionales, motivación autodeterminada, afectos y burnout en deportistas: enfoque multinivel

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    This study aimed to test a multilevel mediation model that examined the relationship between the per­ceived motivational climate created by coaches at team level and the affects and burnout at individual level, as me­diated by the self-determined motivation. Participants were 745 college athletes from various sports, aged 17 to 28 years old (M = 21.46, DT = 2.14) who completed the instruments that evaluated the study variables (PMCSQ-2, SMS-II, PANAS, and ABQ). The results showed that at the within-team level, self-determined motivation was positively related to positive affect; on the contrary, was negatively related to negative affect and three dimen­sions of burnout. At the between-team level, the percep­tion of the task-involving climate was positively related to self-determined motivation, while the ego-involving climate was negatively related to self-determined moti­vation. Similarly, self-determined motivation was positi­vely related to positive affect and negatively negative af­fect, as well as to the three dimensions of burnout. Both the task-involving climate and ego-involving climates showed an indirect effect on well-being and discomfort through self-determined motivation. It is suggested that coaches generate a task-involving climate to promote the well-being of athletes. ResumenEste estudio tuvo como objetivo poner a prueba un mo­delo de mediación multinivel que examinó las relaciones entre la percepción del clima motivacional generado por los entrenadores a nivel de equipo y los afectos y el burnout a nivel individual, mediados por la motivación autodeterminada. Participaron 745 atletas universitarios de diversos deportes, con edades entre 17 a 28 años (M = 21.46, DT = 2.14) quienes completaron los instrumentos que evaluaban las variables del estudio (PMCSQ-2, SMS-II, PANAS y ABQ). Los resultados mostraron que a nivel individual (nivel intra), la motivación autodeterminada se relacionaba positivamente con el afecto positivo; por el contrario, se relacionaba negativamente con el afecto ne­gativo y las tres dimensiones de burnout. A nivel del equipo (nivel entre), la percepción del clima de implica­ción en la tarea se relacionaba positivamente con la mo­tivación autodeterminada, mientras que el clima de im­plicación en el ego se relacionaba negativamente con la motivación autodeterminada. De manera similar, la mo­tivación autodeterminada se relacionaba positivamente con el afecto positivo y negativamente el afecto nega­tivo, así como con las tres dimensiones del burnout. Tanto el clima de implicación en la tarea como el de im­plicación en el ego mostraron un efecto indirecto sobre el bienestar y el malestar a través de la motivación autode­terminada. Se sugiere a los entrenadores generar un clima de implicación en la tarea para potenciar el bie­nestar de los deportistas.  AbstractThis study aimed to test a multilevel mediation model that examined the relationship between the per­ceived motivational climate created by coaches at team level and the affects and burnout at individual level, as me­diated by the self-determined motivation. Participants were 745 college athletes from various sports, aged 17 to 28 years old (M = 21.46, DT = 2.14) who completed the instruments that evaluated the study variables (PMCSQ-2, SMS-II, PANAS, and ABQ). The results showed that at the within-team level, self-determined motivation was positively related to positive affect; on the contrary, was negatively related to negative affect and three dimen­sions of burnout. At the between-team level, the percep­tion of the task-involving climate was positively related to self-determined motivation, while the ego-involving climate was negatively related to self-determined moti­vation. Similarly, self-determined motivation was positi­vely related to positive affect and negatively negative af­fect, as well as to the three dimensions of burnout. Both the task-involving climate and ego-involving climates showed an indirect effect on well-being and discomfort through self-determined motivation. It is suggested that coaches generate a task-involving climate to promote the well-being of athletes.

    Analysis of solar direct irradiance models under clear-skies: Evaluation of the improvements for locally adapted models

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    Direct solar irradiance has to be determined for the design of many energy applications such as photovoltaic systems and concentration systems, and the generation of solar potential maps for energy use. Knowledge of the accurate values of radiation components in a local area will allow optimal sizing of solar energy conversion systems. The estimated values of direct solar irradiance from models are still necessary at those sites where no measurements are available. In this work, different models used for the estimation of the direct component of solar irradiance are analyzed. First, an evaluation of the performance of eight existing original models was performed from which three were selected. Second, the selected models were calibrated to adapt them to our studied geographical area, which is the important aspect of this work, and an assessment of performance improvements for locally adapted models is reported. Experimental data consisted of hourly horizontal global, direct, and diffuse solar irradiance values, provided by the National Meteorological Agency in Spain (AEMET) for Madrid. Long-term data series, corresponding to a total period of time of 32 years (1980–2011), have been used in this study. Only clear sky models were treated at present. The three selected models were adapted to the specific location of Madrid, and root mean square error (RMSE) and mean-biased error were determined. By comparing the performance in the direct horizontal irradiance estimation from existing original and the corresponding locally adapted models, it is found that the values of RMSE decreased from 9.9% to 5.7% for the Louche model, from 7.8% to 7.4% for the Robledo-Soler model, and finally from 8.8% to 6.7% for the European Solar Radiation Atlas model. Thus, significant improvements can be reached when parametric models are locally adapted. In our case, it is up to approximately 4% for the Louche model. It is expected that calibrated algorithms presented in this work will be applicable to regions of similar climatic characteristics.Spanish Government (grant ENE2011-27511) and the Department of Culture and Education of the Regional Government of Castilla y León, Spain (grant BU358A12-2

    A new diffuse luminous efficacy model for daylight availability in Burgos, Spain

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    The determination of optimal illumination conditions in buildings is of great interest both for reducing energy consumption and for exploiting solar resources with greater efficiency and sustainability. The most commonplace method of estimating daylight is the luminous efficacy approach, using the more widely measured solar irradiance. In this present study, a new model of diffuse luminous efficacy over a horizontal surface is proposed. A comparative study of twenty-two classic models is presented, to obtain diffuse illuminance, using both, the original mathematical models and the adapted models with local coefficients, in order to determine the most suitable models for Burgos, a city located in north-western Spain. With this purpose in mind, twelve models are selected for all sky conditions, five models for modelling clear sky, two for partly cloudy sky, and three for overcast sky. These twenty-two models are then compared with the new model both for all sky conditions and for particular sky conditions (clear, partly cloudy, and overcast). The behaviour of the new model showed greater accuracy than most of the classic models under analysis. Hence, the advantage of the diffuse luminous efficacy model that can be applied both to all sky and to particular sky conditions.Spanish Government (Ministerio de Economía y Competitividad) (ENE2014-54601-R). David González Peña would also like to thank the Junta de Castilla-León for economic support (PIRTU Program, ORDEN EDU/310/2015)

    Freshwater fishes and water status in Mexico: A country-wide appraisal.

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    Mexico is the southernmost country in North America, and extends into Central America, south of the Isthmus of Tehuantepec. The northern half of M´exico is located on the Temperate belt and is arid in character (Nearctic), while the rest is within the Tropical belt (Neotropical). Climate varies from extremely temperate desert in the north, to tropical humid in the south.M´exico has more than 500 freshwater fish species, about 271 of them country endemics, and approximately 48 endemics from binational basins. There are still some 30–40 fish species not yet described. There are 563 fish species colonizing coastal flood plain species. In addition to the numbers of colonizing fishes, the burden of introduced exotics has also been growing. In 1904, only 4 species were recognized as exotics; by 1997 the number had increased to 94, and by 2008 to 11

    Thermodynamics of Mixtures Containing Amines. XV. Liquid–Liquid Equilibria for Benzylamine + CH3(CH2)nCH3 (n = 8, 9, 10, 12, 14)

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    Coexistence curves for the liquid−liquid equilibria (LLE) of 1-phenylmethanamine (benzylamine) + CH3(CH2)nCH3 (n = 8, 9, 10, 12, 14) have been determined using the critical opalescence method by means of a laser scattering technique. All of the LLE curves show an upper critical solution temperature (UCST), which increases with increasing n. For systems including a given n-alkane, the UCST decreases in the sequence aniline > 2-methylaniline (o-toluidine) > benzylamine > N-methylaniline > pyridine. This means that amine−amine interactions become weaker in the same order. Most of the DISQUAC interaction parameters for the aliphatic/amine (a,n) and aromatic/ amine (b,n) contacts previously determined for solutions with aniline, o-toluidine, or N-methylaniline have been used for the representation of the LLE data. Only the first dispersive interaction parameter of the (a,n) contact has been modified. The coordinates of the critical points are correctly represented by the model

    Orientational Effects and Random Mixing in 1-Alkanol + Alkanone Mixtures

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    1-Alkanol + alkanone systems have been investigated through the data analysis of molar excess functions, enthalpies, isobaric heat capacities, volumes and entropies, and using the Flory model and the formalism of the concentrationconcentration structure factor (SCC(0)). The enthalpy of the hydroxyl-carbonyl interactions has been evaluated. These interactions are stronger in mixtures with shorter alcohols (methanol-1-butanol) and 2-propanone or 2-butanone. However, effects related to the self-association of alcohols and to solvation between unlike molecules are of minor importance when compared with those which arise from dipolar interactions. Physical interactions are more relevant in mixtures with longer 1-alkanols. The studied systems are characterized by large structural effects. The variation of the molar excess enthalpy with the alcohol size along systems with a given ketone or with the alkanone size in solutions with a given alcohol are discussed in terms of the different contributions to this excess function. Mixtures with methanol show rather large orientational effects. The random mixing hypothesis is attained to a large extent for mixtures with 1-alkanols ≠ methanol and 2-alkanones. Steric effects and cyclization lead to stronger orientational effects in mixtures with 3-pentanone, 4-heptanone, or cyclohexanone. The increase of temperature weakens orientational effects. Results from SCC(0) calculations show that homocoordination is predominant and support conclusions obtained from the Flory model.Ministerio de Ciencia e Innovación, under Project FIS2010-1695
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