1,720,963 research outputs found
Solving the Boltzmann equation in NlogN
No full textIn [33, 32], fast deterministic algorithms based on spectral methods were
derived for the Boltzmann collision operator for a class of interactions including the hard
spheres model in dimension three. These algorithms are implemented for the solution of
the Boltzmann equation in dimension two and three, first for homogeneous solutions, then
for general nonhomogeneous solutions. The results are compared to explicit solutions,
when available, and to Monte-Carlo methods. In particular, the computational cost and
accuracy are compared to those of Monte-Carlo methods as well as to those of previous
spectral methods. Finally, for inhomogeneous solutions, we take advantage of the great
computational efficiency of the method to show an oscillation phenomenon of the entropy
functional in the trend to equilibrium, which was suggested in [16]
Accurate numerical methods for the collisional motion of (heated) granular flows
No full textIn this paper, we extend the spectral method developed in [L. Pareschi, B. Perthame, A Fourier spectral method for homogeneous Boltzmann equations, Trans. Theo. Stat. Phys. 25 (1996) 369-383; L. Pareschi, G. Russo, Numerical solution of the Boltzmann equation I: Spectrally accurate approximation of the collision operator, SIAM J. Numer. Anal. 37 (2000) 1217-1245] to the case of the inelastic Boltzmann equation describing the collisional motion of a granular gas with and without a heating source. The schemes are based on a Fourier representation of the equation in the velocity space and provide a very accurate description of the time evolution of the distribution function. Several numerical results in dimension one to three show the efficiency and accuracy of the proposed algorithms. Some mathematical and physical conjectures are also addressed with the aid of the numerical simulations. © 2004 Elsevier Inc. All rights reserved
A numerical method for the accurate solution of the Fokker-Planck-Landau equation in the nonhomogeneous case
No full textA new approach for the accurate numerical solution of the Fokker-Planck-Landau (FPL) equation has been presented recently in [1, 2]. The method is based on a fast spectral solver for the efficient solution of the collision operator. The use of a suitable explicit Runge-Kutta solver for the time integration of the collision phase permits to avoid excessive small time steps induced by the stiffness of the diffusive collision operator. Here we present the details of a numerical simulation of the relaxation process in a three-dimensional Coulomb gas
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
- …
