1,720,960 research outputs found
Efficiency of Three Wind Turbines Installed on High Plains Region of Algeria
No full textAbstractA Monthly Weibull parameter k and c and a variance for three stations located in the west of high plains of Algeria (Tiaret, Djelfa and El Bayadh) have been estimated using ten years of weather data. The Weibull parameters have been extrapolated to 45 meters taken as height of wind machine rotor. The corresponding mean cubic speeds of the selected sites and the mean monthly power density have been calculated. The most interesting wind potential is obtained for Tiaret region.Using a cut-in speed and a rated speed of a given generators, with 100kW, 600kW and 850kW of nominal power, the monthly mean usable cubic wind speed for the selected sites has been computed.The results show that a 600kW and 850kW wind machine are quite equivalent, in useful power density sense. The choice of an appropriate wind machine will depend of local energy needs. A big decrease noticed during hot season can be completed by a supply source or solar system
Effect of Tests Norms on the Instantaneous Efficiency of a Plate Solar Collector
No full textAbstractRecent Algerian data have shown that affording conventional energy to some rural areas is as yet very costly. The objective of this paper is to calculate the instantaneous efficiency of a plate solar collector according to two different norms, (EN 12975-2 and ASHRAE). For this purpose, a closed loop test bench was been made in the unit of applied research on renewable energies of Ghardaia (Algeria) according to the considered norms. This site is characterized by an important clarity factor of 0.75. Experimental tests were conducted in order to calibrate the test bench, time constant and to calculate the instantaneous efficiency of the collector according to the two norms. In this work the curves of the instantaneous efficiency according to the two norms (optical efficiency and global thermal losses) were drawn as well as the daily efficiency of the collector
Wind farm feasibility study and site selection in Adrar, Algeria
No full textAbstractWind resources present a promising option to be integrated with the conventional energy sources to match the increased demand of electricity. This paper aims to investigate the possibility to set up a wind farm of 10 MW in Adrar, a region located in the south of the country. Using the wasp software, the wind resources of the zone of interest was performed, it indicates that wind speed reach 8.44 m/s at a height of 80 meters. Then, two sites Kaberten(75 north of Adrar) and Zaouia (80 Km south of Adrar) were selected. The wind farm study show that Aouia present the better performance, it can be expected to achieve from this site a production of 40 GW and a full load hours about 4044h
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Study of a Solar PV-Wind-Battery Hybrid Power System for a Remotely Located Region in the Southern Algerian Sahara: Case of Refrigeration
Full text linkThe present work shows an experimental investigation that uses a combination of solar and wind energy as hybrid system (HPS) for electrical generation under the Algerian Sahara area. The generated electricity has been utilized mainly for cooling and freezing. The system has also integrated a gasoline generator to be more reliable. This system is not linked with conventional energy and is not fixed in one region as it is the case of the military base in the Algerian borders. The cooling load consisted of three containers of 10 m3 each with total electricity consumption of 45 kWh/day, two positive rooms (with an internal temperature of +2°C and an external temperature of 35°C) and one negative room (with an internal temperature of -20°C and an external temperature of 35°C). Measurements included the solar radiation intensity, the ambient temperature and the wind speed was collected from Adrar weather station (a windy place in Algeria) for the year of 2010. To simulate the hybrid power system (HPS) HOMER was used. Emissions and renewable energy generation fraction (RF) of total energy consumption are calculated as the main environmental indicator. The net present cost (NPC) and cost of energy (COE) are calculated for economic evaluation. It is found that, for Adrar climates, the optimum results of HPS show a 50% reduction of emissions with 47% of renewable energy fraction
Using Central Composite Experimental Design to Optimize the Degradation of Tylosin from Aqueous Solution by Photo-Fenton Reaction
Full text linkVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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