1,720,973 research outputs found
Modelling and Control of IRST MEMS microphone
No full textThe need for high quality microphones is rising in many application fields, ranging from consumer electronics to distributed environmental control. In this paper, a new MEMS microphone, is presented and its lumped parameter model derived. In the device developed at IRST-ITC, a square planar silicon membrane is suspended over a rigid, gold-plated backplate by means of four flexural springs. This assembly constitutes a capacitor with a mobile armature, which capacitance varies with the acoustic pressure. By measuring such variations of the capacitance, the information on the acoustic pressure is then obtained. However, the measured capacitance variation is not proportional to the acoustic pressure, especially in presence of large signals, and this results in a distortion, affecting the measured quantities. In this paper, we propose the use of a force re-balancing loop, counteracting the acoustic pressure, which maintains the membrane at its equilibrium position during operation. With this solution, the re-balancing command, generated by a properly designed controller, is proportional to the acoustic pressure. Moreover, since the motion of the membrane is negligible, the non-linear effects are almost cancelled, with major benefits on the distortion, when large signals are applied to the microphone. The effectiveness of the solution proposed is demonstrated by simulation results and experiments
Identification and Validation of a Fractional Order Dynamic Model for a Piezoelectric Tactile Sensor
No full textThis paper presents the identification of a
piezoelectric tactile sensor which aims to give the sense of touch to
humanoid robots. The sensor has been characterized in frequency
domain and the low frequency behavior reveals a non-integer
behavior. A simple model based on the a priori knowledge of the
sensor and the observation of the frequency response has been
hypothesized and a least squares method has been applied to
identify the device. The impulse response has been calculated
using the Mittag-Leffler function and validation in time domain
has been performed. Simulation and experimental results are in
good agreement showing that the identified model, despite its
simplicity, is able to represent properly the tactile sensor
A PhysX-based framework to develop rehabilitation using haptic and virtual reality
No full textThe use of virtual reality with haptic interactions seems quite promising for rehabilitation procedure as it provides several advantages: it is possible to change the experiments in the real world based on the patient disability, to use different devices depending on the target of the rehabilitation, and to record quantitative information during the execution of the training session. To cope with the required flexibility and adaptability, we developed a software framework based on the Model/View/Controller pattern that allows to decouple the different modules composing the application. To reduce the cost, the framework is implemented only through the use of freely available libraries. The efficacy of the framework was proved through the implementation of the software for a prototype application based on a five-bar linkage haptic device. © 2013 IEEE
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
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