1,721,007 research outputs found
On approximate system identification with system based orthonormal functions
No full textMechanical Maritime and Materials Engineerin
Advances in data-driven optimization of parametric and non-parametric feedforward control designs with industrial applications
No full textThe performance of many industrial control systems is determined to a large extent by the quality of both setpoint and disturbance feedforward signals. The quality that is required for a high tracking performance is generally not achieved when the controller parameters are determined on the basis of a detailed model of the plant dynamics or manual tuning. This chapter shows that the optimization of the controller parameters by iterative trials, i.e., data-driven, in both parametric and non-parametric feedforward control structures avoids the need for a detailed model of the plant dynamics, achieves optimal controller parameter values, and allows for the adaptation to possible variations in the plant dynamics. Two industrial applications highlight the large benefits of the data-driven optimization approach. The optimization of the feedforward controller parameters in a wafer scanner application leads to extremely short settling times and higher productivity. The optimization of the current amplifier setpoints in a digital light projection (DLP) application leads to nearly constant color rendering performances of the projection system in spite of large changes in the lamp dynamics over its life span
Recovering data from cracked optical discs using Hankel iterative learning control
No full textOptical discs, including Compact Discs (CDs), Digital Versatile Discs (DVDs), and Blu-ray Discs (BDs), can get cracked during storage and usage. Such cracks commonly lead to discontinuities in the data track, potentially preventing reading of the data on the disc. The aim of the present paper is to improve tracking performance of the optical disc drive in the presence of cracks. A Hankel Iterative Learning Control (ILC) algorithm is presented that can perfectly steer the lens during the crack towards the beginning of the track immediately after the crack, i.e., the actuator is steered appropriately during the crack crossing to compensate for the discontinuity in the data track. Experimental results confirm improved reading capabilities of cracked discs. The presented approach potentially enables the recovery of data from cracked discs that were previously considered as unreadable
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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