1,721,002 research outputs found
A comparison of optimal feedback control algorithms for the suppression of microvibrations
No full textModelling of equipment loaded panels for robust control investigations
No full textThis paper develops a modelling technique for equipment load panels which directly produces (adequate) models of the underlying dynamics on which to base robust controller design/evaluations. This technique is based on the use of the Lagrange's equations of motion and the resulting models are verified against those produced by a finite Element Method Model
Robust control of microvibrations
No full textEquipment on-board satellites is often mounted on lightweight panels where microvibrations have to be suppressed to achieve the required level of stability. In the work reported here, attention is restricted to one such mass loaded panel which is an acceptable compromise between problem complexity and the need to gain useful insights as to the benefits (and limitations) of linear active control schemes. The sensors and actuators for the active control scheme to be designed (and eventually implemented) are twin patches of piezoelectric material bonded onto opposite faces of the panel. The use of linear optimal control laws augmented by loop transfer recovery is investigate
LTR control methodologies for microvibrations
No full textMicrovibrations at frequencies between 1 and 1000 Hz generated by on-board equipment can propagate through a satellite's structure and hence significantly reduce the performance of sensitive payloads. This paper describes a Lagrange-Rayleigh-Ritz method for developing models suitable for the design of active control schemes. Here loop transfer recovery (LTR) based controller design methods are employed with this modeling strateg
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
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