1,720,998 research outputs found
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
Classification and Visualization of Power Quality Disturbance-Events Using Space Vector Ellipse in Complex Plane
No full textThis article proposes a novel algorithm employing space vector ellipse (SVE) in a complex plane to classify and visualize power quality disturbance-events (PQDEs). In the proposed method, at first, the time-domain signal and a reference signal, which are separated by 90°, are mapped in a complex 2D coordinates. Thus, the tip of resultant rotating vector traces an ellipse, from which three parameters, namely, semi-major axis, semi-minor axis and inclination angle, are obtained. Then, the ellipse parameters are exploited to classify and visualize nine types of PQDEs, namely, voltage sag, swell, interruption, harmonic, sag-harmonic, swell-harmonic, notch, flicker and transient. To validate the practicability of the proposed approach, an extensive real-time simulation study is carried out on RTDS platform using a test microgrid network to generate a large number of PQDEs. The test events were successfully classified and visualized in complex plane. Moreover, the noisy and practical signals, recorded by IEEE 1159.2 Working Group, were successfully classified to demonstrate the effectiveness of the proposed method.Full Tex
MPC-based Control Interface Development for Frequency Control Design with PSCAD/MATLAB
No full textFrequency control is crucial for the stable operation of a power system. Among various control methodologies, model predictive control (MPC) is one of the promising methods for frequency control considering the system constraints and uncertainties. Nowadays, the simulation of the detailed bulk system with renewable generators is usually executed in Electromagnetic Transient Simulation Analysis Software (e.g., PSCAD/EMTDC). However, the existing PSCAD-MATLAB interface triggers MATLAB through EMTDC at predetermined intervals suitable for continuous system control instead of discrete MPC-based control. Therefore, this paper developed a PSCAD-MATLAB interface with a corresponding module design for MPC-based frequency control. The effectiveness of the proposed interface is validated through the implementation of MPC-based Fast Frequency Response (FFR) in an IEEE-9 bus system that incorporates the Synchronous Generator (SG) and renewable generators. In addition, the impact of different disturbances and the horizon of prediction and control on frequency recovery performance was investigated. In the end, the stability improvement was achieved through both terminal equality constraints and terminal inequality constraints methods.No Full Tex
A feasibility study of the 1.5-axis tracking model in utility-scale solar PV plants
No full textMany solar tracking technologies have been developed with the aim of improving the energy performance of solar PV installations. Among these, single-axis tracking (SAT) systems give good economic prospect for ground-mounted PV plants but experience inevitable power loss when the trackers diverge from the incident solar irradiance during winter. The 1.5-axis tracking (1.5AT) model is developed in recent years to achieve a balance between the benefits and shortcomings of the SAT and dual-axis tracking (DAT) systems. Despite the anticipated superiority of the 1.5AT, there is a lack of literature on the methodology to analytically study the potential and feasibility of the 1.5AT model, especially from a global perspective. In this paper, a comprehensive feasibility study has been conducted to evaluate the energy performance and shading analysis of the 1.5AT model. The developed methodology serves as a general benchmark to explore the prospects of the 1.5AT model at different geographical locations and seasons. This encourages further research and deployment of the 1.5AT model as a potential alternative to improve the return of investment for various PV system stakeholders.Full Tex
An excessive tap operation evaluation approach for unbalanced distribution networks with high PV penetration
No full textRecently, utility-scale photovoltaic (PV) plants in remote areas are drastically increasing due to abundant and low-priced land. These remote areas are usually connected to zone substations through long weak feeders with open-delta step voltage regulators (SVRs) installed in the middle to regulate downstream voltages. However, frequent PV and load power fluctuations can lead to undesirable voltage variations and hence excessive tap operation issues. Currently, it is not clear about the percentage of responsibility by load or PV fluctuations to excessive tap operations. In this article, a novel method based on line-to-line voltage sensitivity and time series evaluation is proposed to respectively quantify the interactions between PV/load fluctuations and tap operations. The accuracy of this method is firmly validated with the measured data from a real-life unbalanced distribution network with high PV penetration. Further, this proposed method is implemented to statistically quantify the causes of excessive tap operations with half-year field data under the support of the local utility and the PV plant owner. The investigation results can provide valuable insights for utilities to better manage the voltage profiles and tap maintenance for remote distribution networks with high PV penetration.Full Tex
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
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