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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Discrete & computational geometry 19 (1998), S. 1-17 
    ISSN: 1432-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. This paper addresses some fundamental questions concerning perturbations as they are used in computational geometry. How does one define them? What does it mean to compute with them? How can one compute with them? Is it sensible to use them? We define perturbations to be curves, point out that computing with them amounts to computing with limits, and (re)derive some methods of computing with such limits automatically. In principle, a line can always be used as a perturbation curve. We discuss a generic method for choosing such a line that is applicable in many situations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Discrete & computational geometry 3 (1988), S. 281-293 
    ISSN: 1432-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The link center of a simple polygonP is the set of pointsx insideP at which the maximal link-distance fromx to any other point inP is minimized. Here the link distance between two pointsx, y insideP is defined to be the smallest number of straight edges in a polygonal path insideP connectingx toy. We prove several geometric properties of the link center and present an algorithm that calculates this set in timeO(n 2), wheren is the number of sides ofP. We also give anO(n logn) algorithm for finding an approximate link center, that is, a pointx such that the maximal link distance fromx to any point inP is at most one more than the value attained from the true link center.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 16 (1996), S. 464-497 
    ISSN: 1432-0541
    Keywords: Search trees ; Dictionaries ; Randomized data structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We present a randomized strategy for maintaining balance in dynamically changing search trees that has optimalexpected behavior. In particular, in the expected case a search or an update takes logarithmic time, with the update requiring fewer than two rotations. Moreover, the update time remains logarithmic, even if the cost of a rotation is taken to be proportional to the size of the rotated subtree. Finger searches and splits and joins can be performed in optimal expected time also. We show that these results continue to hold even if very little true randomness is available, i.e., if only a logarithmic number of truely random bits are available. Our approach generalizes naturally to weighted trees, where the expected time bounds for accesses and updates again match the worst-case time bounds of the best deterministic methods. We also discuss ways of implementing our randomized strategy so that no explicit balance information is maintained. Our balancing strategy and our algorithms are exceedingly simple and should be fast in practice.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 19 (1997), S. 219-242 
    ISSN: 1432-0541
    Keywords: Key words. Input degeneracy, Efficient perturbations, Algorithm implementation, General-dimensional convex hulls.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. This article defines input perturbations so that an algorithm designed under certain restrictions on the input can execute on arbitrary instances. A syntactic definition of perturbations is proposed and certain properties are specified under which an algorithm executed on perturbed input produces an output from which the exact answer can be recovered. A general framework is adopted for linear perturbations, which are efficient from the point of view of worst-case complexity. The deterministic scheme of Emiris and Canny [1] was the first efficient scheme and is extended in a consistent manner, most notably to the InSphere primitive. We introduce a variant scheme, applicable to a restricted class of algorithms, which is almost optimal in terms of algebraic as well as bit complexity. Neither scheme requires any symbolic computation and both are simple to use as illustrated by our implementation of a convex hull algorithm in arbitrary dimension. Empirical results and a concrete application in robotics are presented.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Steroid Biochemistry 20 (1984), S. 1368 
    ISSN: 0022-4731
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 43 (1987), S. 1218-1219 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 116 (1994), S. 101-109 
    ISSN: 1436-5073
    Keywords: infrared spectroscopy ; infrared reflection spectroscopy ; FT-IR ; conversion coating ; phosphate coating ; galvanized steel ; hopeite ; phosphophyllite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hopeite-type phosphate coatings in which zinc is replaced by other metals like nickel, manganese and magnesium are of great interest as conversion coatings on galvanized steel in the automotive and appliance industries. The analytical characterization of such coatings produced in special processes is not possible by XRD because the different types of hopeite are isomorphic. In this paper it is shown that the kind of metal substitution is responsible for certain specific features in the infrared reflection spectra. Furthermore the structural changes caused by dehydration due to heating of the coatings were studied and differences in the thermal stability of the different coatings thus could be observed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 183 (1961), S. 180-186 
    ISSN: 1432-1459
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung Es wird über eine ungewöhnliche Sippe mit 36 Mitgliedern aus fünf Generationen berichtet mit neurologischen und psychopathologischen Krankheitsbildern, die sich nicht nur in der Familie kombinieren, sondern auch gemeinsam bei mehreren Einzelindividuen zeigen.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Geometriae dedicata 32 (1989), S. 1-12 
    ISSN: 1572-9168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper proves that any set of n points in the plane contains two points such that any circle through those two points encloses at least $$n\left( {1/2 - 1\sqrt {12} } \right) + O(1) \approx n/4 \cdot 7$$ points of the set. The main ingredients used in the proof of this result are edge counting formulas for k-order Voronoi diagrams and a lower bound on the minimum number of semispaces of size at most k.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 439 (1978), S. 95-102 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the Mechanism of Molecular Sieve FormationBy means of chemical methods it is shown that the formation of zeolithic molecular sieves proceeds via the following stages: Precipitation of strongly SiO2 containing amorphous products, having varying compositions and containing high-condensed silicate anions; dissolution of these primary products under formation of low-molecular silicate anions; precipitation of a further intermediary product, having, however, a constant composition and containing low-molecular anions (mono- and disilicate); finally, transformation of this intermediate, partially under a further alteration of the silicate anion type, into the crystalline molecular sieve.
    Notes: Es Wurden die Reaktionen, die bei der Bildung von zeolithischen Molsieben ablaufen, mit Hilfe chemischer Methoden untersucht. Dabei zeigte sich, daß zunächst stark SiO2-haltige Niederschläge schwankender Zusammensetzung Ausfallen, die hochkondensierte Silicationen enthalten. Diese primär gebildeten Niederschläge gehen unter Bildung niedermolekularer Silicationen in Lösung, danach fällt ein Zwischenprodukt mit konstanter Zusammensetzung und niedermolekularen (Mono- bzw. Di-) Silicationen aus. Aus diesem Zwischenprodukt entsteht - z. T. unter erneuter Umwandlung des Silicatanionentyps - das kristalline Molsieb.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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