1,721,304 research outputs found
A boundary integral formulation for sound scattered by elastic moving bodies
No full textThis paper deals with the acoustic field scattered by elastic bodies in motion. Starting from the Ffowcs Williams and Hawkings equation for porous surfaces, a boundary integral formulation for the acoustic disturbance is derived. For
moving, vibrating bodies impinged by acoustic waves it yields a unified approach for the determination of surface pressure perturbations and sound radiation. The scattered field is determined from the knowledge of the impinging pressure, without requiring the evaluation of its normal derivative over the surface of the scatterer. A boundary element method is
applied for the numerical solution of the integral formulation. The resulting prediction tool is validated through acoustic analysis of stationary rigid and elastic spherical shells, as well as a wing and a vibrating sphere in uniform motion. The
advantages of the proposed sound scattering formulation are discussed
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
An Unsteady Aerodynamic Formulation for Efficient Rotor Tonal Noise Prediction
No full text"An aerodynamic\/aeroacoustic solution methodology for predction of tonal noise emitted by helicopter rotors and propellers is presented. It is particularly suited for configurations dominated by localized, high-frequency inflow velocity fields as those generated by. blade–vortex interactions. The unsteady pressure distributions are determined by the sectional, frequency-domain Küssner–Schwarz formulation, with downwash including the wake inflow velocity predicted by a three-dimensional, unsteady, panel-method formulation suited for the analysis of rotors operating in complex aerodynamic environments. The radiated noise is predicted through solution of the Ffowcs Williams–Hawkings equation. The proposed approach yields a computationally efficient solution procedure that may be particularly useful in preliminary design\/multidisciplinary optimization applications. It is validated through comparisons with solutions that apply the airloads. directly evaluated by the time-marching, panel-method formulation. The results are. provided in terms of blade loads, noise signatures and sound pressure level contours. An estimation of the computational efficiency of the proposed solution process is also presented..
Changing Needs, Sticky Budgets: Evidence from the Geographic Distribution of US Federal Grants
No full textMost US federal grants are allocated through arguably obsolete formulas, leading
fast growing states to contend that they are not receiving their fair share of the
budget. We shed lights on this issue analyzing the allocation of formula and nonformula
grants during the period 1978-2002. We find that states with fast growing
population are penalized in the allocation of formula programs. The estimated
losses are sizeable and heavily concentrated among the three fastest growing states.
Nevertheless, the majority of the US states is on the winning side, thus providing a
plausible explanation for the status quo bias in budgetary formulas
- …
