1,720,972 research outputs found
Diagnostic of a Flow Process
No full textMany industrial applications, concerning flow process, need to change, maintain or simply monitor the level of liquid in a tank [1-4]. Some key points in designing such control systems derive from the evaluation of some relevant parameters that are difficult to measure, such as outflow coefficients or general leakage coefficients [2]. This paper analyses the possibility of integrating the extended Kalman filter in the control loop in order to determine the parameters influencing the regulator [5-10]. An interesting development of these algorithms is a diagnostic system which can evaluate leakage conditions by monitoring the variation of such parameters and prevent diseases
A diagnostic logic for preventing structural failure in concrete displacing booms
No full textDuring recent decades safety in the workplace has become more and more important. For this reason,
systems for the diagnosis of possible failures represent a particularly attractive solution.
In this paper a healthmonitoring algorithm for a specific kind of construction machinery (concrete displacing
booms) is proposed. It is based on the knowledge of the geometrical and dynamic parameters of the boom,
estimated through a stand-alone self-learning procedure. The proposed algorithm is able to signal alarms
due to the most common failure conditions, such as overload or crack propagation. In detail, the crack propagation
is detected through an Extended Kalman Filter (which identifies the variation of the boom natural
frequencies during its lifetime), while the overload is estimated through force sensors mounted on the actuators.
The results referred to this algorithm, numerically simulated and experimentally reproduced on a specific
test rig, are presented and discussed
Vibration attenuation by means of piezoelectric transducer shunted to synthetic negative capacitance
No full textThis paper deals with vibration attenuation by use of piezo-actuators connected to a Negative Capacitance circuit, generally formed by a synthetic impedance based on operational amplifiers. The goal of this paper is to investigate the means to improve vibration attenuation performances and to avoid instability applying proper choices of the values of the electric elements composing the Negative Capacitance. This is accomplished using an analytic-numerical approach, which furthermore affords a full understanding of this technique. The paper also illustrates the mentioned instability problems at low-frequency and provides indications on how to avoid them. The results this way obtained are finally validated through experimental tests
Characterization and Modelling of the Mechanical and Acoustical Properties of a Pvc Rigid Foam
No full textClosed‐cell cross‐linked PVC foams display high specific strength and stiffness and are frequently used as core of light‐weight sandwich structures, such as inner aircrafts panels. The compressive behaviour of a commercially available foam was investigated under both static and dynamic conditions. An ad‐hoc apparatus was used to obtain tomographic reconstructions during compression; 2D and 3D Digital Image Correlation techniques were used to investigate the topology of the complex microstructure and strain localization phenomena. Finally, a numerical model based on dynamic data was used to predict acoustical damping characteristics of a composite panel made by PVC foam core and aluminium skins
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
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