1,720,952 research outputs found
Irradiance simulation of PV system in urban environments: 3D view factor model validation and comparison with ray-tracing methods
No full textWithin the coming years it is expected that PV installations could be established on every possible surface and terrain, within the urban environment. Due to the complex morphology of buildings in urban environments,systems will likely be more susceptible to partial shading compared to other conventional PV systems. In particular bifacial PV modules are highly susceptible to shading since they rely on irradiance on both the front and the back surface. To better estimate the irradiance received by such systems, particularly in urban environments, much research is conducted to develop fast and accurate simulation tools. The research described in this report investigated the different simulation frameworks that have been developed for modeling bi-facial PV systems, and develop a new simulation framework capable of simulating irradiance within urban environments. Available models capable of simulating rear irradiance differ in input variables considered,simulation time required and accuracy of predictions. Empirical models, for example, can result in inaccurate predictions since not all variables affecting rear irradiance are considered. Only the 3D view factor, back-ward and forward ray tracing methods fulfill the requirements to simulate the backside irradiance/irradiation when the aim is to perform simulations in more complex urban environments. Out of the existing simulation models tested, the backward ray tracing model performed within the Radiance software proved to be the fastest simulation tool for modeling yearly irradiation or a single irradiance measurement incident under free horizon conditions. Time of use (TOU) simulations, however, results in longer simulation time for backward ray tracing performed in Radiance, since a ray tracing simulation at each time instance is required. To calculate the irradiance a receiving surface receives in an urban environment a method is worked out based on view factors and ray casting. Within the software Rhinoceros a CAD design of the surrounding environment is created, while the plug-in Grasshopper is used for the ray casting and mathematical calculations. Through a series of sanity checks, it was determined that the developed methods are reliable for calculating irradiance/irradiation when the aim is to perform simulations in more complex urban environments. It was also identified how different sky models can result in large differences in irradiance simulated. Sky models such as Isotropic, Hay and Davis or simplified Perez underestimates the irradiance, when receiving surfaces are tilted in comparison with the Perez luminance distributed sky model. The model was validated using monitoring station measurements and compared with simulations performed with other ray tracing models. DHI, DNI measurements obtained from the Solys 2 are used for replicating the irradiance measured at the dual-axis and single-axis tracker. Since their orientation was fixed throughout the measurement period they are referred to as POA 1 and POA 2 respectively. With POA 1 and 2 having a 90 and 30 degree tilt respectfully and an azimuth of 67 and 180 degree respectfully. Making POA 1 the front/back side of a typical (bifacial) east-west configuration and POA 2 the front of a tilted (bifacial) module. Two measurement days are considered, a fully overcast day and a clear sunny day. For the overcast day, an relative RMSE value of 23.09% and 11.7% are achieved for POA 1 and 2. For both cases the irradiation was mostly underestimated, considering the negative MBE and positive MAE. On the clear sunny day, relative RMSE values of 20.35% and 5.26% are achieved for POA 1 and 2. The model again mostly underestimates on the sunny day. A simple DHI correction with the factor 1 divided over the SVF at the Solys 2 is performed in order to investigate the impact of potentially corrupted DHI measurements on the irradiance simulations. With relative RMSE value of 19.96% and 5.2% recorded for POA 1 and 2 on the overcast day. While on the sunny day relative RMSE values of 19.38% and 3.77% are achieved for POA 1 and 2 respectively. Only slightly changing the model predictions. When compared to ray tracing models the model performs slightly better than the forward ray tracing model. A possible reason why the forward ray tracing was underestimated was proposed to be due too the small aim area used. However increasing the aim area would require a larger number of rays to maintain the same accuracy which results in longer simulations.Possible improvements to the model could be, adding reflected irradiance term on reflecting surfaces and the Perez luminance distribution sky model.Electrical Engineering | Sustainable Energy Technolog
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
- …
