1,721,046 research outputs found
Methods for the solution of very large flow-control problems that bypass open-loop model reduction
No full textThe numerical discretization of the Navier-Stokes equations may easily lead to millions, or hundreds of millions, degrees of freedom. For the optimal control of such a problem, one is faced with either the solution of the full Riccati equation, numerically intractable for large systems, or with openloop model reduction, which may fail to capture the dynamics of interest. Here we present recent developments in our group about a third alternative: the Riccati-less solution of the unreduced optimal flow-control problem. These include a minimal-energy control algorithm based on the unstable eigenvectors alone, an iterative algorithm for the feedback kernel when the control is of much lower dimension than the state, and an iterative procedure for the leading eigenvalues and eigenvectors of the direct-adjoint Hamiltonian matrix that bypasses the solution of the Riccati equation
Minimal-energy control feedback for stabilization of bluff-body wakes based on unstable open-loop eigenvalues and left eigenvectors
No full textMinimal-energy control feedback for stabilization of bluff-body wakes based on unstable open-loop eigenvalues and left eigenvectors
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An optimal feedback controller for the reduction of turbulent energy in 3D plane-duct flow
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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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