1,725,255 research outputs found
RIGID-PLASTIC FINITE-ELEMENT ANALYSIS OF SHEET-METAL FORMING PROCESSES USING A SELECTIVE-MEMBRANE SHELL FORMULATION
No full textIn most sheet-metal forming processes a large part of the deforming material exhibits stretch-dominant characteristics and the bending effect is found to exist only in a limited portion of the total deforming region. Thus the use of shell or continuum elements for the whole region is not economic. A selective membrane/shell (M/S) scheme is proposed which combines the layered degenerated shell elements with membrane elements. In the proposed scheme, membrane elements and layered degenerated shell elements are employed selectively according to the characteristics of the deformation, using the suggested criterion to consider the bending effect. The selective M/S scheme is introduced into rigid-plastic finite-element analysis for plane-strain, axisymmetric and three-dimensional problems. The computational results are then compared with the results of experiment, the comparison showing that with the selective M/S scheme the bending effect can be considered effectively whilst the computational time is reduced significantly
AN IMPROVED METHOD FOR THE APPLICATION OF BLANK-HOLDING FORCE CONSIDERING THE SHEET THICKNESS IN THE DEEP-DRAWING SIMULATION OF PLANAR ANISOTROPIC SHEET
No full textIn the analysis of deep drawing, the tractional distribution due to the blank holding of the flange influences greatly the final deformation of the drawn cup. The tractional boundary conditions are related directly to the thickness distribution developed during the drawing process. However, the tractional boundary conditions are usually assumed by applying uniform nodal forces along the peripheral nodes of the flange. In the present work, the blank-holding force is considered to be distributed as a function of thickness over each node in the flange. During the process, when the nodal thickness in the flange reaches a critical value, the blank-holding force and accordingly the blank-holding traction are distributed such as to be assigned to the corresponding node according to the suggested scheme of thickness consideration. Deep drawing of circular and square cups is analyzed by using the rigid-plastic finite-element method considering planar anisotropy. The method is shown to improve convergence and stability as well as the prediction of ear development
A variable step-size diffusion affine projection algorithm
No full textThis paper presents a new variable step-size diffusion affine projection algorithm (VSS-DAPA) to advance the filter performance of the diffusion affine projection algorithm (DAPA). The proposed VSS strategy is developed for the DAPA, which can solve the distributed estimation problem over diffusion networks well. To obtain the optimal step size reasonably, we seek the update recursion of mean-square deviation (MSD) that is suitable for the DAPA. The step size is optimally given through the minimization for the MSD of the DAPA at each iteration. The derived step size through the MSD minimization improves the filter performance with respect to the convergence and the estimation error in steady state. The results based on simulations demonstrate that the proposed VSS-DAPA performs better than the existing algorithms with a system-identification scenario in diffusion network. Copyright (C) 2015 John Wiley & Sons, Ltd.1110sciescopu
RIGID-PLASTIC FINITE-ELEMENT ANALYSIS OF SHEET-METAL FORMING PROCESSES USING CONTINUOUS CONTACT TREATMENT AND MEMBRANE ELEMENTS INCORPORATING BENDING EFFECTS
No full textAn improved method of contact treatment is developed in which both the FEM (finite element method) mesh and the tool surfaces are described with parametric patches which have C1 continuity or more. The FEM mesh at the current configuration is globally converted into smooth surface patches of net form. A continuous sheet surface normal scheme is devised by using the globally smoothed mesh surface. A robust and efficient contact search algorithm is also developed in connection with the proposed continuous contact treatment. As an improved version of conventional membrane element, the BEAM (abbreviated from Bending Energy Augmented Membrane) element is newly developed based on node spring. In order to verify the effectiveness of the proposed continuous contact treatment and BEAM element, deep drawing processes of complicated parts including actual auto-body panel are analysed. Comparisons with the available experiment and analysis show that the proposed continuous contact treatment in connection with BEAM elements can be effectively applied to the analysis of sheet metal forming processes for arbitrarily curved parts with deformation regions in which the bending effect must be taken into account
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
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
- …
