DSpace Collection: Volume 4 Number 3
http://hdl.handle.net/10525/1539
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Teaching Materials Repository
http://hdl.handle.net/10525/1601
Title: Teaching Materials Repository<br/><br/>Authors: Stanchev, Peter; Nisheva-Pavlova, Maria; Geske, John<br/><br/>Abstract: The paper presents results from the development of a methodology and corresponding software tools for building an academic repository.The repository was filled up with gaming material. The repository architecture and key features of the search engine are discussed. The emphasisfalls on solutions of the large set of problems concerning the development ofproper mechanisms for semantics-based search in a digital repository.Fri, 01 Jan 2010 00:00:00 GMTExtension of the C-XSC Library with Scalar Products with Selectable Accuracy
http://hdl.handle.net/10525/1600
Title: Extension of the C-XSC Library with Scalar Products with Selectable Accuracy<br/><br/>Authors: Zimmer, Michael; Krämer, Walter; Bohlender, Gerd; Hofschuster, Werner<br/><br/>Abstract: The C++ class library C-XSC for scientific computing has beenextended with the possibility to compute scalar products with selectable accuracy in version 2.3.0. In previous versions, scalar products have alwaysbeen computed exactly with the help of the so-called long accumulator. Additionally, optimized floating point computation of matrix and vector operations using BLAS-routines are added in C-XSC version 2.4.0. In this articlethe algorithms used and their implementations, as well as some potentialpitfalls in the compilation, are described in more detail. Additionally, thetheoretical background of the employed DotK algorithm and the necessarymodifications of the concrete implementation in C-XSC are briefly explained.Run-time tests and numerical examples are presented as well.Fri, 01 Jan 2010 00:00:00 GMTQuadratic Time Computable Instances of MaxMin and MinMax Area Triangulations of Convex Polygons
http://hdl.handle.net/10525/1599
Title: Quadratic Time Computable Instances of MaxMin and MinMax Area Triangulations of Convex Polygons<br/><br/>Authors: Mirzoev, Tigran; Vassilev, Tzvetalin<br/><br/>Abstract: We consider the problems of finding two optimal triangulations of a convex polygon: MaxMin area and MinMax area. These are thetriangulations that maximize the area of the smallest area triangle in a triangulation, and respectively minimize the area of the largest area trianglein a triangulation, over all possible triangulations. The problem was originally solved by Klincsek by dynamic programming in cubic time [2]. Later,Keil and Vassilev devised an algorithm that runs in O(n^2 log n) time [1]. Inthis paper we describe new geometric findings on the structure of MaxMinand MinMax Area triangulations of convex polygons in two dimensions andtheir algorithmic implications. We improve the algorithm’s running time toquadratic for large classes of convex polygons. We also present experimentalresults on MaxMin area triangulation.Fri, 01 Jan 2010 00:00:00 GMTApproximating the MaxMin and MinMax Area Triangulations using Angular Constraints
http://hdl.handle.net/10525/1598
Title: Approximating the MaxMin and MinMax Area Triangulations using Angular Constraints<br/><br/>Authors: Mark Keil, J; Vassilev, Tzvetalin<br/><br/>Abstract: We consider sets of points in the two-dimensional Euclideanplane. For a planar point set in general position, i.e. no three points collinear,a triangulation is a maximal set of non-intersecting straight line segmentswith vertices in the given points. These segments, called edges, subdivide theconvex hull of the set into triangular regions called faces or simply triangles.We study two triangulations that optimize the area of the individual triangles:MaxMin and MinMax area triangulation. MaxMin area triangulation is thetriangulation that maximizes the area of the smallest area triangle in thetriangulation over all possible triangulations of the given point set. Similarly,MinMax area triangulation is the one that minimizes the area of the largestarea triangle over all possible triangulations of the point set. For a point setin convex position there are O(n^2 log n) time and O(n^2) space algorithmsthat compute these two optimal area triangulations. No polynomial timealgorithm is known for the general case. In this paper we present an approach<br/><br/>Description: * A preliminary version of this paper was presented at XI Encuentros de Geometr´iaComputacional, Santander, Spain, June 2005.Fri, 01 Jan 2010 00:00:00 GMTComputer Networks Security Models - A New Approach for Denial-of-Services Attacks Mitigation
http://hdl.handle.net/10525/1597
Title: Computer Networks Security Models - A New Approach for Denial-of-Services Attacks Mitigation<br/><br/>Authors: Tsvetanov, Tsvetomir<br/><br/>Abstract: Computer networks are a critical factor for the performance of amodern company. Managing networks is as important as managing any otheraspect of the company’s performance and security. There are many tools andappliances for monitoring the traffic and analyzing the network flow security.They use different approaches and rely on a variety of characteristics of thenetwork flows. Network researchers are still working on a common approachfor security baselining that might enable early watch alerts. This researchfocuses on the network security models, particularly the Denial-of-Services(DoS) attacks mitigation, based on a network flow analysis using the flowsmeasurements and the theory of Markov models. The content of the papercomprises the essentials of the author’s doctoral thesis.Fri, 01 Jan 2010 00:00:00 GMTAn Improvement to the Achievement of the Griesmer Bound
http://hdl.handle.net/10525/1596
Title: An Improvement to the Achievement of the Griesmer Bound<br/><br/>Authors: Hamada, Noboru; Maruta, Tatsuya<br/><br/>Abstract: We denoted by nq(k, d), the smallest value of n for which an [n, k, d]q code exists for given q, k, d. Since nq(k, d) = gq(k, d) for all d ≥ dk + 1 for q ≥ k ≥ 3, it is a natural question whether the Griesmer bound is attained or not for d = dk , where gq(k, d) = ∑[d/q^i], i=0,...,k-1, dk = (k − 2)q^(k−1) − (k − 1)q^(k−2). It was shown by Dodunekov [2] and Maruta [9], [10] that there is no [gq(k, dk ), k, dk ]q code for q ≥ k, k = 3, 4, 5 and for q ≥ 2k − 3, k ≥ 6. The purpose of this paper is to determine nq(k, d) for d = dk as nq(k, d) = gq(k, d) + 1 for q ≥ k with 3 ≤ k ≤ 8 except for (k, q) = (7, 7), (8, 8), (8, 9).Fri, 01 Jan 2010 00:00:00 GMTSearch for Wieferich Primes through the use of Periodic Binary Strings
http://hdl.handle.net/10525/1595
Title: Search for Wieferich Primes through the use of Periodic Binary Strings<br/><br/>Authors: Dobeš, Jan; Kureš, Miroslav<br/><br/>Abstract: The result of the distributed computing projectWieferich@Homeis presented: the binary periodic numbers of bit pseudo-length j ≤ 3500 obtainedby replication of a bit string of bit pseudo-length k ≤ 24 and increasedby one are Wieferich primes only for the cases of 1092 or 3510.Fri, 01 Jan 2010 00:00:00 GMT