1,720,973 research outputs found
Forward- and Reverse-Traveling Waves in DP Phenomenology: Does Inverted Direction of Wave Propagation Occur in Classical Models?
No full textDPOAE short and long latency components and the beamforming effect: Experiment and model
No full textThe DPOAEs measured in the ear canal is the vector sum of two different components. The nonlinear and the linear components are characterized by very different group delay so that they can be effectively separated in the time-frequency domain. The two components are differently sensitive to the f2/f1 ratio. In particular, in the case of the nonlinear component, if the ratio approaches unity, due to the increase of the overlap between the f2 and f1 excitation patterns, the generation region becomes wider. The widening of the generation region causes a large negative interference phenomenon, due to the fact that the contribution to the fdp amplitude comes from wavelets with different phase. This behavior cannot be observed in the case of the linearly generated component, because the phase spread is compensated in the forward traveling wave path to the fdp place (beamforming effect). In this study, the result of analytical and numerical modeling are compared to experimental data, showing that the different models are able to reproduce different aspects of the DPOAE generation and transmission phenomenology
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
Active structural-acoustic control on interior noise of a plate-cavity system using FxNLMS algorithm
No full textIn recent years, environmental noise has been attracting increasing attention due to its negative impact on people’s physical and
mental health.One of the promising solutions tomitigate noise is the application of smart structures,whose acoustic performance
is actively controlled. In the presentwork, an Active Structural- Acoustic Control (ASAC) strategy is developed using a plate-cavity
system in order to abate the interior noise in some locations of the cavity. The employed algorithm is the Filtered-x Normalized
Least Mean Squares (FxNLMS), which is typically applied to Active Noise Cancellation (ANC) problems. The peculiarity of this
work is that the control is applied directly to the vibration of the plate, similar to Active Vibration Control (AVC) strategies. The
major innovation in this case is that, instead of evaluating the acoustic benefits due to a vibration reduction, here the sound field is
controlled directly by closing the loop on the acoustic pressure. The algorithm has been implemented in Single-Input Single-Output
(SISO) and Single-Reference Multiple-Output (SRMO) configurations, where the latter is a first step toward a multichannel
architecture. In contrast with many existing applications, here the cross-effects between different actuators are considered in the
implementation of the algorithm, thus improving the performance in the controlled positions. The experimental test bench
adopted for validation is a plate-cavity system called Noise Box, which is made up of a single-layer glass panel and a reinforced
concrete structure, designed to simulate the interior sound field of a vehicle cabin. The plate was instrumented with piezoelectric
patches used as actuators,while condenser microphoneswere used as sensors. First, a numericalmodel of the systemwas created
to develop the control logic. Then, an experimental campaign was carried out to validate the results
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
- …
