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  • 1
    Electronic Resource
    Electronic Resource
    The separation of viscous jets (1985)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 28 (1985), S. 23-25 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A viscous jet is not usually observed to separate from a sharp edge in the manner expected theoretically. In the present paper the separation of a creeping jet emerging from a tube with a rounded exit is considered. As a separation criterion, in the absence of surface tension, we propose that the traction normal to the nozzle surface drops to zero at the separation point. Boundary-element calculations then show a behavior that agrees with experimental data and with previous finite-element computations. They also permit the Michael condition to be observed at separation, so that the discrepancy between finite-element calculations and theory is removed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865185
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  • 2
    Electronic Resource
    Electronic Resource
    Forest development on Rakata, Panjang and Sertung: Contemporary dynamics (1979–1989) (1992)
    Springer
    GeoJournal 28 (1992), S. 185-199 
    Details
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract Ten years of quantitative studies of forests on Krakatau demonstrate the vegetational difference resulting from multiple successional pathways. Multivariate analysis of the forest data indicates strong statistical separation of forest types within and between the islands. Current rates of forest growth and change within the Krakatau islands are found to vary considerably. The canopy architecture of Panjang and Sertung is observed to have changed dramatically over the past six years while the pace of change on Rakata appears relatively slow, particularly in the uplands. In an area studied in near-coastal, lowland Rakata, seedling recruitment of Neonauclea calycina is poor and its continued status as an overwhelmingly dominant species must be in question. A slightly more diverse forest appears to be developing below about 120 m elevation, in which Dysoxylum gaudichaudianum is an increasingly important component. Disturbance phenomena, ranging from continuing volcanism to individual tree falls, are found to be critical to an understanding of forest development on the islands. Despite the increasing role of Dysoxylum on Rakata our data indicate a continuing divergence of compositional types within the lowland forest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00177232
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  • 3
    Electronic Resource
    Electronic Resource
    Ecological aspects of plant colonisation of the Krakatau Islands (1992)
    Springer
    GeoJournal 28 (1992), S. 201-211 
    Details
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Abstract Species assemblage data from the Krakatau Islands, Indonesia, are presented for the period 1883 to 1989 (including previously unpublished data from the 1989 survey). Since 1934, 16 additional families of higher plants have colonised. Recent arrivals at the family level are mostly of zoochorous species of forest tree, indicating (subject to the effects of disturbance) a continuing increase in potential niche space within the island interiors. The data for Rakata (an uninterrupted prisere) conform to a successional explanation in which identifiable ecological groups of plants exhibit differing colonization and turnover patterns. Animal-dispersed canopy tree species and species which are widespread within the group, exhibit a very low probability of extinction once they have colonized successfully. There are, however, several constraints on the rapid spread of species within the group, in particular those connected to local dispersal (eg lack of large terrestrial mammals). In respect of dispersal to the group, partial survey data for the island of Sebesi from 1921 (revised) and 1989 provides the basis for comment as to the changing biogeographical circumstances of the Sunda Straits and the role of Sebesi as a ‘stepping stone’ island. The varied data discussed in the paper indicates that with the exception of the strand-line, no component of the Krakatau flora or vegetation has yet approached a stable composition. Both floral and faunal diversification are argued to be proximally controlled not only by dispersal opportunities but also by the dynamics of the dominant life-forms of the system, ie, the forest trees. Such hierarchical links, across trophic boundaries, should receive greater recognition in the construction of island biogeographical theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00177233
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  • 4
    Electronic Resource
    Electronic Resource
    The age of the British chalk grassland (1987)
    [s.l.] : Nature Publishing Group
    Nature 329 (1987), S. 434-436 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Willow Garth is a 5-hectare can lying in the Great Wold Valley (grid reference TA 126676) at an altitude of -18 m Ordnance Datum. The woodland is flanked by arable fields which, when ploughed, reveal a patchwork of peaty and sandy deposits. To the north, Willow Garth is bounded by an underfit ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/329434a0
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  • 5
    Electronic Resource
    Electronic Resource
    On the elastic fibre pull-out problem: asymptotic and numerical results (1982)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 33 (1982), S. 251-265 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit geben wir einige asymptotische Ergebnisse für das Ausziehen einer beinahe starren Faser aus einer elastischen Matrix. Die asymptotischen Resultate sind aufO(ε 2) genau, woε=(ln 2l/R)−1 bedeutet, falls die Faser aus einer halbunendlichen Matrix ausgezogen wird. Sie sind aufO(h 2/l 2) genau, falls die Faser aus einer Matrix ausgezogen wird, welche einen Zylinder vom Radiush füllt. Eine Interpolationsformel, die das richtige asymptotische Verhalten fürh/l=0 undh/l → ∞ aufweist, wird vorgeschlagen. Diese asymptotischen Ergebnisse werden durch numerische Methoden mindestens bis geometrische Verhältnisse vonl/R≧9 bestätigt. Wir berichten ebenfalls über eine gewisse numerische Bestätigung eines früheren approximativen Resultats für das Ausziehen einer starren Faser mit einem vergrößerten sphärischen Kopf.
    Notes: Summary In this paper we present some asymptotic results for the pull out of a nearly-rigid fibre from an elastic matrix. The asymptotic results are accurate toO(ε 2), whereε=(ln 2l/R)−1, if the fibre is pull-out from a semi-infinite matrix, and toO(h 2/l 2) if the fibre is pull-out from a matrix contained in a cylindrical container of radiush. Here R andl are the fibre radius and length, respectively. An interpolation formula is suggested which yields correct asymptotic behaviour at bothh/l=0 andh/l → ∞. These asymptotic results are confirmed by numerical methods to at least an aspect ratio ofl/R≧9. We also report some numerical confirmation of a previous approximate result for the pull out of a rigid fibre with an enlarged spherical end.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00944975
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  • 6
    Electronic Resource
    Electronic Resource
    On the steady flow of a Newtonian fluid between two parallel disk (1984)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 35 (1984), S. 912-919 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Zusammenfassung Wir zeigen, daß die ständige Strömung einer viskosen Flüssigkeit von mäßiger Reynoldszahl zwischen zwei parallelen Scheiben eine exakte Lösung hat, die die Form einer Potenzreihe annimmt. Wenn wir diese exakte Lösung anwenden, wird das Zwei-Punkte-Grenzwertproblem für diese Art von Strömung reduziert auf ein nichtlineares algebraisches System, das dann durch eine Optimierungsmethode gelöst werden kann. Angegeben werden Resultate für zwei Einzelfälle: die kontinuierliche Quetschströmung und die Strömung für Koaxialscheiben.
    Notes: Summary We show that the steady flow of a viscous fluid of moderate Reynolds number between two parallel disks has an exact solution which takes the form of a power series. Employing this exact solution the two-point boundary value problem for this class of flow is reduced to a nonlinear algebraic system which is then solved by a standard optimization method. Results are given for two particular cases, the continuous squeezing flow and the coaxial-disk flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00945453
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  • 7
    Electronic Resource
    Electronic Resource
    Viscous flow through corrugated tube by boundary element method (1985)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 36 (1985), S. 475-480 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Zusammenfassung Das Problem der schleichenden Bewegung eines Newton'schen Fluids durch ein Rohr mit sinusförmig gewellter Wand wird mit Hilfe der “Boundary Element”-Methode gelöst. Übereinstimmung mit einer anderen numerischen Methode wird festestellt. Zudem wird gezeigt, daß eine früher gefundene Störungstheorie nur gültig ist wenn die Wellenamplitude klein (〈0.3a) und die Wellenlänge groß (〉3πa) ist (a=mittlerer Rohrradius).
    Notes: Summary The creeping flow of a Newtonian fluid through a sinusoidally-corrugated tube is solved by the Boundary Element Method. Agreement with another numerical method is noted. In addition, it is shown that previous perturbation theory is valid only when the corrugation amplitude is small (〈0.3a) and the wavelength of the corrugation is large (〉3πa), wherea is the mean radius of the tube.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00944637
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  • 8
    Electronic Resource
    Electronic Resource
    Stratified Newtonian and non-Newtonian flow calculations by the boundary element method (1992)
    Springer
    Computational mechanics 10 (1992), S. 345-357 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper stratified Newtonian and viscoelastic flow problems are solved using a direct boundary integral formulation. Both the free surface and fluid/fluid interface geometries are unknown in advance. The technique is tested by comparison with some previously published finite element solutions and found to perform well. The extrusion of Newtonian/ Oldroyd-B and Oldroyd-B/Oldroyd-B fluids is considered in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00364255
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  • 9
    Electronic Resource
    Electronic Resource
    Three dimensional bi-component extrusion simulations by the boundary element method (1995)
    Springer
    Computational mechanics 16 (1995), S. 114-123 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In the present paper the boundary element method is implemented to solve fully three-dimensional bi-component flows of Newtonian fluids. The solution formulation follows that of Tran-Cong and Phan-Thien (1988a). In particular the coextrusion from square and triangular dies is studied with a view to establishing the dependence of the extrudate shape on viscosity ratio, interface shape, feed ratio and die shape. An ad hoc two-layer model is also investigated which may provide the means to predict viscoelastic extrudate shape without performing a full viscoelastic calculation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365865
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  • 10
    Electronic Resource
    Electronic Resource
    Three dimensional bi-component extrusion simulations by the boundary element method (1995)
    Springer
    Computational mechanics 16 (1995), S. 114-123 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  In the present paper the boundary element method is implemented to solve fully three-dimensional bi-component flows of Newtonian fluids. The solution formulation follows that of Tran-Cong and Phan-Thien (1988a). In particular the coextrusion from square and triangular dies is studied with a view to establishing the dependence of the extrudate shape on viscosity ratio, interface shape, feed ratio and die shape. An ad hoc two-layer model is also investigated which may provide the means to predict viscoelastic extrudate shape without performing a full viscoelastic calculation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365865
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