1,721,040 research outputs found
A nonlinear dynamics approach for incorporating wind-speed patterns into wind-power project evaluation.
Full text linkWind-energy production may be expanded beyond regions with high-average wind speeds (such as the Midwest U.S.A.) to sites with lower-average speeds (such as the Southeast U.S.A.) by locating favorable regional matches between natural wind-speed and energy-demand patterns. A critical component of wind-power evaluation is to incorporate wind-speed dynamics reflecting documented diurnal and seasonal behavioral patterns. Conventional probabilistic approaches remove patterns from wind-speed data. These patterns must be restored synthetically before they can be matched with energy-demand patterns. How to accurately restore wind-speed patterns is a vexing problem spurring an expanding line of papers. We propose a paradigm shift in wind power evaluation that employs signal-detection and nonlinear-dynamics techniques to empirically diagnose whether synthetic pattern restoration can be avoided altogether. If the complex behavior of observed wind-speed records is due to nonlinear, low-dimensional, and deterministic system dynamics, then nonlinear dynamics techniques can reconstruct wind-speed dynamics from observed wind-speed data without recourse to conventional probabilistic approaches. In the first study of its kind, we test a nonlinear dynamics approach in an application to Sugarland Wind-the first utility-scale wind project proposed in Florida, USA. We find empirical evidence of a low-dimensional and nonlinear wind-speed attractor characterized by strong temporal patterns that match up well with regular daily and seasonal electricity demand patterns
Reduction of transpiration through foliar application of chitosan
No full textIn this study, we investigate the potential of chitosan, a natural beta-1-4-linked glucosamine polymer, to reduce plant
transpiration. Chitosan was applied foliarly to pepper plants and water use was monitored. Peppers were grown in pots
in growth-chambers, where transpiration was measured by weighing pots. In an accompanying field study, water use was
determined by monitoring soil moisture depletion with time domain reflectometry.An automated irrigation system replenished
the water used each day. Plant biomass and yield were determined to calculate biomass-to-water ratios. Differences in canopy
resistance between control and chitosan treated plants were analyzed with the aid of the Penman–Monteith equation. Scanning
electron microscopy (SEM) and histochemical analyses demonstrated that chitosan induced closure of the plant’s stomata,
resulting in decreased transpiration. Foliar application of chitosan reduced water use of pepper plants by 26–43% while
maintaining biomass production and yield. We suggest that chitosan might be an effective antitranspirant to conserve water
use in agricultur
Evaluation of the WEPP model and digital elevation grid size, for simulation of streamflow and sediment yield in a heterogeneous catchment
No full textThe Water Erosion Prediction Project (WEPP) model was tested using data from a detailed study conducted on experimental plots in the Apennines Mountain Range, northern Italy. Runoff, soil water and sediment data, together with weather information, were collected on an hourly basis at the study site. WEPP was first applied to simulate transient surface runoff, soil water and erosion. Two important input parameters, the biomass energy ratio for crop and the effective hydraulic conductivity of surface soil, were calibrated using field-observed runoff, soil water, erosion and plant biomass data. The calibrated model was then used to simulate the hydrologic and erosion impacts of three typical crop rotations, thereby to evaluate their abilities in reducing surface runoff and sediment yield. Results indicated that, with the definition of a restrictive layer at the bottom of the soil profile and the calibration of the two crucial model parameters, WEPP could adequately account for the water balance for the modeled experimental plot. For the study area, continuous corn with a conservation practice that delayed primary and secondary tillages produced low surface runoff and soil erosion, from both field observation and WEPP modeling. However, this mono-cultural practice may lead to accelerated soil-quality degradation. On the other hand, a four-year-rotation, corn–wheat–alfalfa–alfalfa, was predicted to substantially reduce soil erosion and has potential to become a sustainable cropping system under the pedo-climatic settings of the study area
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
Variations 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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