1,721,172 research outputs found
Multi-criteria geometric optimization problems in Layered Manufacturing (Extended Abstract)
No full text) Jayanth Majhi Ravi Janardan Michiel Smid y Jorg Schwerdt y 1 Introduction Layered Manufacturing (LM) is an exciting new technology which enables complex 3D parts to be built directly from their CAD models, as a stack of 2D layers. It is revolutionizing the field of CAD/CAM because it allows the designer to create rapidly a physical version of the CAD model (literally on the desktop) and to "feel and touch" it, thereby detecting and correcting flaws in the model early on in the design cycle. Moreover, it opens up the possibility of directly building functional parts composed of multiple materials---something that is not possible via conventional manufacturing methods. Figure 1 illustrates a well-known LM process called StereoLithography [11]. The input is a surface triangulation of the CAD model in a format called STL. The STL model is oriented suitably, sliced by horizontal planes, and built vertically, as follows: The laser traces out the contour of each layer on the surfa..
Implementing Dictionaries Using Hashing
No full textIntroduction This chapter is based on Mehlhorn [5]. Many algorithms manipulate sets. For example, a compiler uses a symbol table to keep track of the identifiers that are used in a program. Identifiers are strings of letters and digits. With each identifier, associated information such as type, scope, and address, is stored. As another example, the catalogue of a library maintains, among other things, names of authors. With each author, associated information such as title and ISBN number is stored. Typical operations that have to be supported in such applications are: access(x; S): if x 2 S, then return the information associated with x. Otherwise, report that x is not an element of S. insert(x; S): insert element x into S, i.e., set S := S
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
On the Circumradius of Acute Point Sets
No full textA set of points in IR n is said to be in acute position, if the angle determined by any triple of points is at most equal to ß=2. This paper considers the problem of computing the maximum circumradius of any set of n + 1 points in IR n that is in acute and general position and that has diameter one. It is shown that for n = 3, this maximum circumradius is at most equal to one. For arbitrary n, a lower bound of 1 4 p 2n on the maximum circumradius is proved. 1 Introduction We consider a problem in combinatorial geometry that arose in an attempt to represent finite metric spaces in finite-dimensional Euclidean spaces, and that was posed to the author by Naveen Garg. Let S be a set of points in IR n . This set is said to be in acute position, if the angle determined by any triple of points is at most equal to ß=2. We say that S is in general position, if for every 1 j n \Gamma 1, no j + 2 points of S are contained in a j-dimensional plane. In this paper, we consider the cas..
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
A Plane 1.88-Spanner for Points in Convex Position
Full text linkLet S be a set of n points in the plane that is in convex position. For a real number t>1, we say that a point p in S is t-good if for every point q of S, the shortest-path distance between p and q along the boundary of the convex hull of S is at most t times the Euclidean distance between p and q. We prove that any point that is part of (an approximation to) the diameter of S is 1.88-good. Using this, we show how to compute a plane 1.88-spanner of S in O(n) time, assuming that the points of S are given in sorted order along their convex hull. Previously, the best known stretch factor for plane spanners was 1.998 (which, in fact, holds for any point set, i.e., even if it is not in convex position)
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
Discretized approaches to schematization
No full textFor both the Fréchet distance and the symmetric difference, we show that finding the simple polygon S restricted to a grid that best resembles a simple polygon P is NP-complete, even if: (1) we require that S and P have equal area; (2) we require turns to occur in a specified sequence for the Fréchet distance; (3) we permit S to have holes for the symmetric difference. Compilation copyright © 2017 Michiel Smid Copyright of individual papers retained by authors.All right reserved
Discretized approaches to schematization
Full text linkFor both the Fréchet distance and the symmetric difference, we show that finding the simple polygon S restricted to a grid that best resembles a simple polygon P is NP-complete, even if: (1) we require that S and P have equal area; (2) we require turns to occur in a specified sequence for the Fréchet distance; (3) we permit S to have holes for the symmetric difference. Compilation copyright © 2017 Michiel Smid Copyright of individual papers retained by authors.All right reserved
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