1,720,961 research outputs found
A penalty-projection algorithm for incompressible fluid-structure interaction
No full textThis paper deals with boundary optimal control problems for the temperature and Navier-Stokes equations, where we propose to transform a boundary optimal control problem into a distributed problem through the lifting function approach of nonhomogeneous boundary conditions. The lifting function approach defines controls in the function spaces which are naturally associated to the volume variables, without stronger regularity requirements. For strong and robust optimization the state-adjoint system must be solved in a coupled way. To this purpose, we propose the use of domain decomposition Vanka-type solvers. With this type of solvers the problem is split into small blocks of finite element subdomains with a small number of degrees of freedom, so that an optimal solution is computed by solving the fully coupled state- adjoint system on each subdomain. We present a numerical study of a class of optimal control problems where temperature is the observed quantity and the control quantity corresponds to the boundary values of the fluid temperature in a portion of the boundary. The control region for the observed quantity is a part of the domain where it is interesting to match a desired temperature value. In a multi-physics framework the desired temperature matching can be achieved by the contribution of different physical mechanisms, involving not only boundary temperature control but also boundary velocity, the overall effect of which is studied. We consider a classical finite element method for the numerical discretization of such problems and we illustrate the results of some test cases for the state, adjoint and control solution, in order to show that candidate boundary controls can be computed in an effective manner
A multilevel domain decomposition solver for monolithic fluid-structure interaction problems
No full textThis paper deals with multilevel domain decomposition techniques inside a multigrid framework to solve fluidstructure interaction (FSI) problems via the Finite Element Method (FEM). The mathematical problem consists of the Navier-Stokes equations in the Arbitrary-Lagrangian-Eulerian (ALE) formulation coupled with a non-linear incompressible structure model (Neo-Hookean). The coupling between the structure and the fluid, due to the important added-mass effect, is enforced within a unique solver. This kind of problem can be tackled efficiently by domain decomposition techniques. The solution strategy presented in this work is to solve several small local subproblems over subdomain patches using Vanka smoothing inside a multigrid algorithm. The results of a benchmark are presented in order to show the potentiality of the proposed solution method in terms of accuracy and efficiency
Review of Split and Unsplit Geometric Advection Algorithms
No full textAn overview of existing split and unsplit Volume-of-Fluid transport algorithms is presented. The emphasis is set on establishing a parallel between both types of algorithms, and their performance regarding accuracy and mass conservation
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
FISSICU platform on CRESCO-ENEA grid for thermal-hydraulic nuclear engineering (CIRTEN Report CERSE-UNIBO RL 1302/2010, XCIRTEN-LP5-004)
No full textThe FISSICU (FISsione/SICUrezza) platform for CFD thermal-hydraulics is set on the CRESCO-ENEA GRID cluster located in Portici. The platform contains codes for microscale, intermediate and system scale simulations for components of nuclear plants and facilities. For direct three-dimensional numerical simulations the platform contains codes such as TRIO_U and SATURNE. At intermediate scale the platform implements codes such as NEPTUNE and for system level CATHARE will be available soon. The platform contains the SALOME application for code coupling and a large number of mesh generators and visualization tools. All the codes run starting from mesh input files with common formats. GMESH and SALOME MESH are open-source reference mesh generators that can be found in the platform together with conversion tools. The output is written in common format and can be visualized through the PARAVIEW application. A brief guide through the platform codes and tools with reference mesh and output formats is presented
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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