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  • 1
    Monograph available for loan
    Monograph available for loan
    Cambridge : Cambridge University Press
    Call number: PIK N 076-93-0119
    Type of Medium: Monograph available for loan
    Pages: 578 S.
    Edition: 1. Aufl.
    ISBN: 0521426308 , 0-521-41631-0
    Series Statement: Proceedings of the second world Climate Confrence
    Branch Library: PIK Library
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 63 (1993), S. 402-412 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Übersicht Es werden die Phänomene untersucht, die beim Kontakt elastischer Kugeln unter der Einwirkung von Kräften mit veränderlicher, unidirektionaler Tangentialkomponente mit veränderlichem Vorzeichen und veränderlicher Normal-komponente auftreten. Das Kontaktgesetz beruht auf der von H. Hertz [3] eingeführten Annahme, daß sich beide Körper physikalisch wie elastische Halbräume verhalten. Wir nehmen konstante Spannungsrichtungen im Gleitgebiet an, um mit Hilfe sogenannter Cattaneo-Mindlin-Funktionen das tangentiale Randwertproblem zu lösen. Die Spannungsverteilung der Cattaneo-Mindlin-Theorie [2], [8] ist rotationssymmetrisch und hat einen typischen Knickpunkt am Rand des Haftgebiets an der Stelle ϱ=a 1 *, füra 1 *〈a 1, mit dem Radiusa 1 * des Haftgebiets und dem Radiusa 1 des Kontaktgebiets. Die allgemeine Lösung des tangentialen Kontaktproblems kann als eine Summe von Cattaneo-Mindlin-Funktionen dargestellt werden. Die geeignete Überlagerung von zwei cattaneo-Mindlin-Funktionen ergibt eine neue Cattaneo-Mindlin-Funktion, was die Berechnung der Kraft und der Verschiebung beträchtlich vereinfacht. Wir leiten eine Formel für die Kraft-Verschiebungs-Beziehung bei allgemeinen Belastungsgeschichten her, die durch Differentiation auf die Nachgiebigkeiten von Mindlin & Deresiewicz [9] reduziert werden kann. Im Gegensatz zu Mindlin & Deresiewicz hängt unsere Formel nur von den Punkten momentanen HaftensP i (für 1≦i≦N−1) und von den aktuellen Verschiebungen ξ N und ζ N in tangentialer und normaler Richtung des anfänglichen Kontaktpunktes ab, was die Lösung vereinfacht. Es ermöglicht auch eine Verallgemeinerung für schiefe Belastungsgeschichten mit elliptischen Kontaktgebieten und Tangentialkräften mit veränderlicher Richtung [4]. Schließlich wird ein Algorithmus angegeben, welcher die notwendige Zahl von Cattaneo-Mindlin-Funktionen bestimmt.
    Notes: Summary An investigation is made of the phenomena occurring at the contact of elastic spheres, subjected to forces with varying tangential component, in one direction, with changing sign, and varying normal component. The contact law is based on the assumption, introduced by H. Hertz [3], that both bodies behave physically like elastic half-spaces. We assume constant stress directions in the slip area in order to use so-called Cattaneo-Mindlin functions to solve the tangential boundary value problem. The stress distribution of the Cattaneo-Mindlin theory [2], [8] is rotational symmetric and has a typical break at the border of the stick area at ϱ=a 1 * fora 1 *〈a 1, with the radiusa 1 * of the stick area and the radiusa 1 of the contact area. The general solution of the tangential contact problem can be written as a sum of Cattaneo-Mindlin functions. The appropriate superposition of two Cattaneo-Mindlin functions yields a new Cattaneo-Mindlin function, which simplifies the calculation of the force and the displacement. We will arrive at a formula for the force-displacement relation of general load-histories, which can be reduced to the compliances of Mindlin & Deresiewicz [9] by differentiation. In contrast to Mindlin & Deresiewicz our formula depends only on the points of instantaneous adhesionP i , for 1≦i≦N−1, and the current displacements ξ N , ζ N in tangential and normal direction of the initial contact point, which simplifies the solution. It also allows a generalization for oblique load-histories with elliptical contact areas and tangential forces in varying directions [4]. Finally an algorithm is given, which determines the essential number of Cattaneo-Mindlin functions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 64 (1994), S. 235-248 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Übersicht In diesem Artikel wird der Stoß zweier geometrisch und materiell ähnlicher Kugeln untersucht, welche um die gemeinsame Normale ihres Kontaktgebietes rotieren. Die Lösung des statischen Kontaktproblems, bei welchem die Kugeln durch eine konstante Normalkraft zusammengedrückt und anschließend durch ein monoton steigendes Torsionsmoment um die Kontaktnormale belastet werden, wurde von Lubkin gefunden. Die Überlagerung der Lubkin-Funktionen für unterschiedliche Kontaktgebiete ergibt das allgemeine Kontaktgesetz für eine Folge endlicher Normalverschiebungs-und Torsionsinkremente. Die Drehung am Stoßende erhält man durch numerische Integration der Drallgleichung und des Kontaktgesetzes. Die Nassi-Shneiderman-Diagramme des Kontaktalgorithmus und des Stoßprogramms werden abgebildet. Einige Ergebnisse werden vorgestellt und mit einer asymptotischen Theorie für vollständiges Haften und vollständiges Gleiten verglichen.
    Notes: Summary In this article, the collison of two geometrically and materially similar elastic spheres, which are rotating around the common normal of their contact area, is analysed. The solution of the static problem, when the spheres are pressed together by a constant normal force and are then subjected to a monotonously increasing torsional couple about the contact normal, has been found by Lubkin. Superposition of Lubkin's solutions for varying contact areas yields the general contact law for finite sequences for normal and torsional displacement increments. The torsional rotation at the end of impact is obtained from numerical integration of the angular equation of motion and the contact law. The Nassi-Shneiderman diagrams of the contact algorithm and the impact algorithm are presented. Some results are plotted and compared with an asymptotic theory for complete adhesion and complete sliding in the contact area.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 347 (1990), S. 628-628 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] WHEN palaeontologists or archaeologists discover a rich microvertebrate fauna, they are so concerned with its biochrono-logical and palaeoenvironmental infor-mation content that they forget to ask questions about the origin of these small vertebrates' assemblages, the causes of their death and ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 107 (1994), S. 101-115 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The general solution for tangential loading histories of similar bodies with circular areas of contact is outlined and applied to the tangential impact. Classical numerical methods use an interpolation function for the stress distribution on a set of points and obtain the stress distribution for given displacements by inversion of a linear equation system. Our solution avoids large systems of simultaneous equations and gives exact solutions for loading histories in form of finite, successive displacement increments. The general equations of motion for the impact are derived and applied to the case, where the normal and the tangential equations of impact are uncoupled. The Nassi-Shneiderman diagrams of the contact algorithm and the impact algorithm are presented. The solution is compared with other results from earlier publications. A tangential coefficient of restitution, which determines the behaviour of the bodies after impact, is plotted as a function of two parameters.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 47 (1991), S. 543-549 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Continuous diffuse scattering is noted in electron diffraction patterns from polymethylene compounds such as n-paraffins and polyethylene. In a projection down the chain axes, experimentally produced by solution crystallization, the diffuse scatter in hk0 patterns disappears at low temperature, in accord with a thermal-diffuse-scattering model, which explains the intensity distribution and its temperature dependence. For a projection onto the chain axes, experimentally achieved by epitaxic orientation on benzoic acid crystals, the 0kl, as well as 3D projections, contain diffuse scatter which does not disappear at low termperature. Its origin appears to be due to frozen-in longitudinal chain static displacements, perhaps as much as 0.25 Å, as indicated by a model for this disorder.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biochemistry 62 (1993), S. 255-285 
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The growth-regulating factor MDGI belongs to the fatty acid binding proteins of which the amino acid sequence is known. Starting from hydrodynamic and dichroic measurements which yield estimations about mass, diameter, thickness, and content of α and β structure of the MDGI protein, we used theoretical methods to calculate the structures and electrostatic properties of selected β-chain sequences. The hydrophobic character of possible binding sites for fatty acids is demonstrated by the molecular electrostatic potential and field of this structures. A nonstandard turn element, formed by an H-bridge between polar side chains, Lys-Leu-Gly-Val-Glu, which connects two extended β chains, was found. Bound oleic acid could be able to stabilize such turn structure, which seems to appear also at the entrance of the cavity of two other proteins. The optimization of an oleic acid-turn van der Waals complex results in an interaction energy of about -50 kJ/mol originating mainly from the dispersion term and shows the participation of the four hydrophobic side chains Phe 64, Leu 66, Val 68, and Phe 70. Of these, at least Phe 64 and Phe 70 are known as possible binding sites of fatty acids.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 1990-01-01
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
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