1,720,956 research outputs found
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
Local and global numerical analysis of a porous screen in free-stream flow
No full textA porous screen in a free-stream flow poses a model system for the analysis of nets, as used in fishing and aquaculture. In such applications, the forces on the net inform operational design and safety choices, whereas the flow past the net relates to the mixing of flow and nutrients in the wake. Most existing analyses of the flow past porous screens are based on experiments or simplified potential flow models. While both methods can lead to insightful results, open questions related to the details of the flow field, viscous effects, and the accuracy of the simplified models remain. To address these questions, we set up and run high-fidelity numerical simulations of the free-stream flow past a two-dimensional model porous screen. The screen is formed by placing a series of solid circular cylinders orthogonal to a free-stream flow. As the number of cylinders is increased, the gaps between them decreases, which increases the solidity of the screen. The use of a free-space domain removes any artificial numerical blockage effects, consistent with a free-stream flow.
Our analysis provides insights in the variation of the mean force coefficients as a function of the screen solidity, as well as their temporal fluctuations and spatial distributions across the screen. Further, we compute the flow rates and mean velocities through the screen gaps, and visualize the local flow field and wake. The results show that the mean value and fluctuations of the drag coefficients increase with the screen solidity. Further, the flow rate through the screen decreases monotonically as the solidity increases. The mean velocity through the screen behaves non-monotonically however, as it first increases and then decreases with screen solidity. Comparing our results to an existing potential model shows that the model predicts the flow rate well. However, the total drag coefficient is significantly lower in the predictions compared to the simulation results, pointing to the need for a better understanding of the pressure jump across the screen.S.M
Recommended from our members
Performance Analysis of a Utility-Scale Wave Energy Converter
Full text linkA six degree of freedom (6DOF) point-absorber wave energy converter (WEC) called LUPA is being developed at Oregon State University. This research focused on analyzing a full- scale LUPA, called LUPA20, to answer the following questions: 1) How does a full-scale WEC perform due to various factors; 2) What are the implications of using a mooring system attached to a WEC; 3) How does a mooring system affect the “optimal” power take-off (PTO) damping coefficient; 4) How does a WEC affect the incoming waves? One of the first parts of this research consisted of conducting an exhaustive power take-off (PTO) damping coefficient search to obtain the “optimal” PTO damping coefficients of LUPA20. Those “optimal” PTO damping coefficients were used to determine the energy production of LUPA20. The results indicate that LUPA20 has an approximate power rating of 96 KW when analyzing the average power results of time domain simulations using a certain range of sea states. To develop a comprehensive LUPA20 model, a mid-water float mooring setup was implemented into the LUPA20 time domain simulations. Simulations were run using various extreme sea states to determine the effects mooring lines might have on LUPA20. The power results indicate the mooring lines have a relatively large effect on the power production. This is evident in the 4.7% difference between the peak power values and the 6.9% difference between the average power values. A PTO damping coefficient sensitivity study was conducted to determine whether the “optimal” PTO damping coefficient change when mooring lines are implemented. The PTO damping coefficient sensitivity study indicated mooring lines do not have a significant effect on the “optimal” PTO damping coefficient. As well as understanding the effects mooring lines have on WEC performance, understanding the effects LUPA20 has on the incoming waves was also studied. A transmission coefficient (K_t) analysis was conducted to determine how much energy LUPA20 is absorbing from the incoming waves. The minimum K_t is 0.84, which indicates LUPA20 can absorb a maximum of approximately 16% of the incoming wave energy
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
Recommended from our members
Wave Energy Converter Archetypes and Power Performance Representation
Full text linkThere is a continuing and increasing need to develop renewable energy technologies that are efficient, cost-effective and produce usable forms of energy. Wave energy converters (WECs) have an opportunity to play a key and significant role in the integration of renewable energy technologies on a commercial scale.
It is estimated that waves off the United States coast could provide ~64% of U.S electricity generation in 2018 [1]. A priority requirement to assist marine energy development is a better understanding what types of WECs are currently being developed and their current associated power production performance estimates.
This report explains the key differences between different WECs and the various power take-off (PTO) systems within then. Overviews of how the WEC operates, basic dimensions of the WEC, and a performance matrix are provided for each WEC archetype. The performance matrices illustrate the amount of power generated based on the significant wave height and the wave energy period, as per the International Electrotechnical Commission TC-114 Technical Specifications
Recommended from our members
Global Wave Energy Testing Sites : Seafloor Bathymetry and Slope
Full text linkA review of global marine energy test sites and associated bathymetric condition
- …
