1,720,963 research outputs found
A NEW FORMULATION FOR THE BOUNDARY ELEMENT ANALYSIS OF HEAT CONDUCTION PROBLEMS WITH NONLINEAR BOUNDARY CONDITIONS
No full textBaranoglu, Besim/0000-0003-2005-050XAn effective numerical method based on the boundary element formulation is presented to solve heat conduction equations which are governed by the Fourier equation, with nonlinear boundary conditions on one or more sections of the prescribed boundary. The solution involves the manipulation of the system matrices of the boundary element method and obtaining a smaller ranked matrix equation in which the unknown is only the temperature difference over the nonlinear boundary condition region. This way, the iterations to deal with the nonlinear conditions are performed faster. After finding the solution over the nonlinear boundary condition region, the solution over the entire boundary is obtained as a post-process through a prescribed relation. An example with a proven exact solution is employed to assess the results.Science Citation Index Expande
Predicting the Topology of the Bending Corner in Bending of Ultra High Strength Steels Through Finite Element Analysis
No full textBaranoglu, Besim/0000-0003-2005-050X; Billur, Eren/0000-0001-9984-3697In bending of plates, unlike the case of sheet metal forming, a 3-D stress state is valid. Moreover, apart from the some very specific cases, the plane strain assumption is not appropriate either. Therefore; bending of thick ultra-high strength steel (UHSS) plates is a deformation process where 3-D stress and strain states exist in general. This study basically focuses on the prediction of the bending corner topology with non-linear finite element analysis method, since the laser-cut edges of the UHSS are particularly prone to edge cracking during bending operation. Within the scope of this study, an experimental set-up is designed which consists of bending tools and a servo mechanical press. The samples were bent by means of this set-up in an air-bending operation up to 90 degrees. This experimental work was followed by optical scanning measurements. And finally, the FEA results and the scanning data were compared in 3-D space. The results showed good correlation. As a future study, the 3-D strain field of the bending corner will be tried to be measured by a professional digital image correlation (DIC) system which could probably give more precise data when combined with the data from FEA.FNSS Defense Systems Co. Inc.; Nurol Makina Sanayi A.S.This contribution presents a certain portion of an internally-funded R&D project of FNSS and Nurol Makina companies. Therefore, the authors would like to thank to managerial boards of FNSS Defense Systems Co. Inc. and Nurol Makina Sanayi A.S. for their financial supports. Thank are also extended to MFCE for the use of their facilities.Conference Proceedings Citation Index - Scienc
Robust and Adaptive Control Design of a Drilling Rig During the Operating Modes
No full textBaranoglu, Besim/0000-0003-2005-050X; Nobahar, Amir/0000-0002-8248-4963;Oil well drilling towers have different operating modes during a real operation, like drilling, tripping, and reaming. Each mode involves certain external disturbances and uncertainties. In this study, using the nonlinear model for the modes of the operation, robust and/or adaptive control systems are designed based on the models. These control strategies include five types of controllers: cascaded proportional-integral-derivative, active disturbance rejection controller, loop shaping, feedback error learning, and sliding mode controller. The study presents the design process of these controllers and evaluates the performances of the proposed control systems to track the reference signal and reject the uncertain forces including the parametric uncertainties and the external disturbances. This comparison is based on the mathematical performance measures and energy consumption. In addition, three architectures are presented to control the weight on bit during drilling process, and also to maintain a preset constant weight on bit, two control approaches are designed and presented.Scientific and Technical Research Council of Turkey (TUBITAK) [115G007]This work was supported by the Scientific and Technical Research Council of Turkey (TUBITAK) under the Grant 115G007
The use of dual reciprocity boundary element method in coupled thermoviscoelasticity
No full textA boundary element formulation is presented in a unified form for the analysis of thermoviscoelasticity problems. The formulation contains the thermoelastic material as a special case. The boundary-only nature of boundary element method is retained through the use of particular integral method; where the particular solutions are evaluated with the aid of dual reciprocity approximation. The proposed formulation can be used in both coupled and uncoupled thermoviscoelasticity analyses, and it permits performing the analysis in terms of fundamental solutions of viscoelastodynamics and diffusion (thermal) equation, and eliminates the need for using the complicated fundamental solutions of coupled thermoviscoelasticity. The formulation is performed in Fourier space where any viscoelastic model can be simulated via the correspondence principle. The determination of the response in time space requires the inversion which can be carried out conveniently by using the fast Fourier transform algorithm. For assessment, some sample problems, both uncoupled and coupled, are considered and whenever possible comparisons are given with the exact data. It is found that the formulation developed in the study, even with the simplest base function proposed in literature, may be used reliably in thermoviscoelasticity analysis, at least, for the problems with finite solution domains
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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