1,721,179 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
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
LES of Jets and Sprays Injected into Crossflow
Get PDFThe objective of this thesis is to numerically simulate a fluid jet injected into a crossflow of the same or another fluid, respectively. Such flows are encountered in many engineering applications in which cooling or mixing plays an important role, e.g. gas turbine combustors. The jet in crossflow (JICF) is used both for cooling and for injecting liquid fuel into the air stream prior to combustion. The numerical simulations regard three space dimensions and track also the flow dynamics by integrating the governing equations in time. The spatial and the temporal resolution are such that the large-scale flow structures are resolved. Such an approach is referred to as large eddy simulations (LES). The motion of the fuel droplets is treated by Lagrangian particle tracking (LPT) with the stochastic parcel method, along with submodels for evaporation, collision, breakup, and a novel submodel for aerodynamic four-way coupling: The particle drag is corrected depending on relative positions of the particles. Mixture fraction and temperature transport equations are solved to enable the modeling of droplet evaporation and the mixing of the gaseous fuel with ambient air. In the simulations of multiphase JICF, several computed results are shown to be inconsistent with the underlying assumptions of the LPT approach: The magnitude of the Weber numbers indicates that droplets are not spherical in large portions of the flow field in wide ranges of parameters which are relevant for gas turbine operation. The magnitude of the droplet spacing suggests that aerodynamic interaction (indirect four-way coupling) among droplets may be important. The LES with aerodynamic four-way coupling reveals significant effects compared to two-way coupling for monodisperse particles in a dense multiphase flow. For single-phase JICF, the impact of nozzle shape on the large-scale coherent structures and the mixing is studied. Effects of circular, square, and elliptic nozzles and their orientation are considered. It is demonstrated that square and elliptic nozzles with blunt orientation raise turbulence levels significantly. The scalar distribution in a cross-sectional plane is found to be single-peaked for these nozzles whereas circular and the nozzles with pointed orientation show double-peaked scalar distribution. It is the nozzles with a single-peaked distribution which are the better mixers. The differences and similarities of single- and multiphase JICF are compared, and it is demonstrated that the flow field solution for multiphase flow approaches the flow field solution of single-phase flow in the limit of small Stokes numbers
Fast-ion diagnostic in fusion plasmas by velocity-space tomography
No full textVelocity distribution functions of ions in high-performance fusion plasmas can deviate substantially from simple Maxwellian distributions. They can be strongly anisotropic or have local maxima at velocities larger than the thermal velocities. The distribution functions of the fast ions in the plasma are often the key to understanding heating, current drive, and various plasma instabilities. However, the distribution functions are unfortunately not always predictable for plasmas with instabilities. These often cause fast-ion transport that is not fully understood. The measurement of fast-ion velocity distribution functions is therefore crucial to operate high-performance plasmas for eventually harvesting energy. However, until now this measurement could not be done. The velocity-space tomography approach put forward in this thesis allows this measurement, providing a new meeting ground between theory and observation. This allows studies of the behavior of fast ions in fusion plasmas at an unprecedented level of detail.Traditionally fast-ion measurements are presented in terms of spectra of a measured quantity that is particular to each diagnostic, e.g. the power density of radiation, photon or particle count rates, or the times-of-flight in a detector. These spectra in diagnostic measurables are then compared with synthetic spectra based on numerical simulations. The results of such comparisons are often hard to interpret since it is not immediately clear how to attribute any discrepancies between measurements and predictions to the fast-ion distributions. To exploit the rich information about fast ions contained in the spectra by traditional procedures, we need to consider hundreds of measurements, keeping in mind nuisance parameters and the complicated relationships between the measurements and velocity space. Borrowing from usual position-space tomography, velocity-space tomography provides a way to process this wealth of information at once. It provides a 2D image that is straightforward to interpret, is the best useful fit to hundreds of simultaneous measurements, combines data from different diagnostics, shows the fundamental quantity of interest rather than quantities of secondary interest, and accounts for nuisance parameters.Until today measurements by the diagnostics fast-ion D-alpha spectroscopy, collective Thomson scattering, neutron emission spectrometry, gamma-ray spectroscopy, and fast-ion loss detectors installed at the tokamaks ASDEX Upgrade, JET, MAST, DIII-D, and EAST have been interpreted using velocity-space tomography. We have measured strongly non-Maxwellian fast-ion velocity distribution functions in plasmas heated by neutral beam injection and by electromagnetic wave heating in the ion cyclotron range of frequencies. The interaction of energetic particles with plasma instabilities has revealed strong selectivity in velocity space. This has filled gaps in our yet incomplete understanding of the physics of the redistribution of fast ions due sawteeth, neoclassical tearing modes, and Alfvén eigenmodes. Fast-ion densities have been measured for the first time, and first movies following the time evolution of the fast-ion velocity distribution function in plasmas with instabilities have been presented. Velocity-space tomography based on the foreseen set of fast-ion diagnostics at the next-step fusion device ITER has revealed that co-passing and counter-passing particles, which are two out of three major classes of particles in tokamaks, cannot be told apart. An additional detector is now proposed that would allow this distinction.Velocity-space tomography has also revealed the density, drift velocity, and anisotropic temperatures of the thermal ions, has deblurred measurements with fast-ion loss detectors, and has provided a new approach to interpret gamma-ray measurements of runaway electrons. This thesis describes the development of velocity-space tomography and demonstrates its utility for the interpretation of fast-ion measurements.<br/
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
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