1,720,959 research outputs found
THE PROCESSING OF HYPERBOLOID SURFACES USING WIRE ELECTRICAL DISCHARGE MACHINING – THEORETICAL ASPECTS
Get PDFThe paper presents an original method that can be used for cutting hyperboloid surfaces using wire electrical discharge machining (WEDM). The processing method, which has only been partly revealed by the author in certain relatively low-impact Romanian publications, is now fully delineated in the form of two papers that focus on both the theoretical and practical aspects of the processing of hyperboloid surfaces using wire electrical discharge machining. This paper presents the theoretical facets of the matter, revealing the mathematical aspects that underpin the methods of generating hyperboloid surfaces. The way in which a hyperboloid surface can be materialized for any mathematical equation of a hyperbola, which defines the axial profile of the hyperboloid of revolution that can be generated using wire electrical discharge machining is minutely explained, thus ensuring the availability of all information required by the practical implementation of the processing
THE PROCESSING OF HYPERBOLOID SURFACES USING WIRE ELECTRICAL DISCHARGE MACHINING – PRACTICAL ASPECTS
Get PDFThe paper presents practical aspects of an original method that can be used for cutting hyperboloid surfaces using wire electrical discharge machining (WEDM). The processing method, which has only been partly revealed by the author in certain relatively low-impact Romanian publications, is now fully delineated in the form of two papers that focus on both the theoretical and practical aspects of the processing of hyperboloid surfaces using wire electrical discharge machining. This paper presents the practical aspects of the method of generating hyperboloid surfaces. The numerical and geometric simulation of the generation of hyperboloid surfaces using wire electrical discharge machining is shown, together with the way of programming the processing, certain technological limitations regarding the processing of hyperboloid surfaces, and real-world conclusions concerning the generation of surfaces being processed via wire electrical discharge machining
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
THE PROCESSING OF PLANE COMPLEX CONTOURS USING WIRE ELECTRICAL DISCHARGE MACHINING
Get PDFThe paper presents two original methods that can be used in the case of cutting complex contours using wire electrical discharge machining (WEDM): the osculating circle method and the three-point circle definition method. The expression "complex contour" refers to a contour that comprises random technical curves which cannot be cut using the interpolation equipment of CNC WEDM machines. The two methods proposed approximate the arcs of random technical curves through arcs of a circle and can be implemented in practice on any WEDM machine. Even though they were devised for WEDM processing specifically, the methods proposed can also be used when dealing with the cutting of complex contours using other nonconventional means of processing, such as: LASER cutting, electron- or ion-beam cutting, plasma cutting, and even water jet cutting
AN INNOVATIVE APPROACH TO REDUCING DEEP HOLE SHAPE DEVIATIONS
No full textThe paper presents an innovative method for improving the shape precision of deep cylindrical holes, made by using WEDM (wire electrical discharge machining) technology.
Following the presentation of some general aspects, the mathematical model of the deformation of the middle fibre of the wire electrodes employed in the WEDM manufacturing process is presented in detail. This deformation generates significant distortions in shape, especially when the depth of the holes executed is significant. These distortions can be balanced out by sloping the wire electrode at a convenient angle during the manufacturing process. The principle of improving the shape precision, together with some experimental results, are presented next
AN OVERVIEW OF WIRE ELECTRODE VIBRATIONS ON WEDM
Get PDFThe paper presents the particularities of wire electric discharge machining (WEDM) technology regarding electrode-tool vibration (wire-tool vibration). It shows how the electrode-tool vibrates, as well as the shape of thevibration. The novelty of the approach is also explained, together with an overview of the factors which impact wire electrode processing and which are essential in overcoming the natural complexity of the phenomena involved. To that extent, the presented mathematical model – which uses only slight approximations to allow its study – can successfully be used in practicalimplementations to improve the accuracy of processing through wire electric discharge machining, especially with regard to positional precision and shape of surfaces machined
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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