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  • Cell & Developmental Biology  (25,032)
  • Engineering  (12,632)
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  • 1
    Electronic Resource
    Electronic Resource
    Implementation of a lamina-based constitutive relationship for analysing thick compositesWork performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48 (1992)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 35 (1992), S. 1031-1043 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The finite element implementation of a lamina-based elastic constitutive relation appropriate for describing the three-dimensional (3-D) behaviour of fibre composite laminated media is presented. Unconstrained by the two-dimensional restrictions accompanying plate and shell theories, this approach resolves the macro 3-D deformation fields found in 'thick' laminated or filament wound composites without requiring each lamina to be individually discretized to assign material properties. In rectangular isoparametric solid elements where laminae locally parallel an element 'face', the implementation represents 'exactly' the elastic laminate behaviour by replacing the discrete lamina stiffnesses with continuous polynomial moduli functions. Attributable directly to the lamina constitutive relationship used, appropriate for fibre-dominated material systems, the implementation automatically preserves interlaminar continuity of tractions and displacements within each element for laminates assembled from a single lamina type. The order of the effective moduli functions is determined by the element kinematics and by requiring identical net mid-surface elemental forces and moments. In general, this representation substantially reduces the number of stored variables and through-thickness integrations required, and allows 'exact' integration by higher-order Gaussian quadrature. Additionally a single element may span any portion or number of laminae, thus allowing nearly arbitrary meshing and solution resolution. Several numerical examples using 3-D 8-node isoparametric solid elements demonstrate the approach's convergence and overall behaviour.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620350506
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  • 2
    Electronic Resource
    Electronic Resource
    Incomplete factorization for finite element methods (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1101-1109 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An incomplete factorization iterative scheme with ORTHOMIN acceleration is evaluated for three-dimensional finite element applications. Both heat conduction and combined heat and fluid flow are investigated. Computational efficiency is investigated for both linear (8 node) and quadratic (27 node) elements as well as for various degrees of LU Decomposition. The factorization schemes worked well with both types of elements, and a variable factorization scheme, which distributes the level of factorization, performed well on difficult heat and fluid flow problems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620230608
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  • 3
    Electronic Resource
    Electronic Resource
    Finite element methods for geothermal reservoir simulation (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 7 (1983), S. 75-86 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Two finite element algorithms suitable for long term simulation of geothermal reservoirs are presented. Both methods use a diagonal mass matrix and a Newton iteration scheme. The first scheme solves the 2N unsymmetric algebraic equations resulting from the finite element discretization of the equations governing the flow of heat and mass in porous media by using a banded equation solver. The second method, suitable for problems in which the transmissibility terms are small compared to the accumulation terms, reduces the set of N equations for the Newton corrections to a symmetric system. Comparison with finite difference schemes indicates that the proposed algorithms are competitive with existing methods.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610070108
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  • 4
    Electronic Resource
    Electronic Resource
    Finite difference techniques for modelling geothermal reservoirs (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 3 (1979), S. 355-366 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Two finite difference algorithms suitable for long-time simulation of the exploitation of a two-phase geothermal reservoir are presented. One is based on the hopscotch method proposed by Saul'yev1 and analysed further by Gordon2 and Gourlay.3 The other is based on the well-known ADI method. Both methods use a Newton-Raphson iterative technique in order to obtain accurate solutions of the non-linear difference equations involved. Rapid convergence of the iterative schemes occurs both for single-phase and two-phase reservoir problems. One- and two-dimensional model problems are presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610030404
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  • 5
    Electronic Resource
    Electronic Resource
    On modelling the unloading-reloading behaviour of soils (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 2 (1978), S. 87-93 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610020107
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  • 6
    Electronic Resource
    Electronic Resource
    AN IMPLICIT PROJECTION ALGORITHM FOR SIMULTANEOUS FLOW OF PLASTICITY AND DAMAGE IN STANDARD GENERALIZED MATERIALS (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 3065-3082 
    Details
    ISSN: 0029-5981
    Keywords: biomechanics ; damage ; finite element method ; plasticity ; standard generalized material ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Motivated by mechanical analysis of cancellous bone, a 3D constitutive law describing the simultaneous flow of rate-independent plasticity and damage is developed in the framework of thermodynamics of irreversible processes with internal variables. Following the hypothesis of standard generalized materials, a free energy and a dissipation potential are postulated and the associated flow rules derived with the tools of convex analysis. On the computational side, the classical implicit projection (or catching up) algorithm used in plasticity is extended to account for the additional flow of damage. Due to the existence of a dissipation potential, linearization of the incremental algorithm provides a symmetric tangent operator. Numerical resolutions of several boundary value problems and a biomechanical application are presented to illustrate the potential of the constitutive model and demonstrate the quadratic convergence of the algorithm.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Structure of the scales of Dermophis and Microcaecilia (Amphibia: Gymnophiona), and a comparison to dermal ossifications of other vertebrates (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 25-43 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structures of the dermal scales and the cells surrounding the scales in two species of gymnophione amphibians were studied using histochemistry and light, scanning and transmission electron microscopy. Scales are composed of a basal platt of several layers of unmineralized collagenous fibers topped with mineralized squamulae. Squamulae are composed of numerous mineralized globules and mineralized, thick collagen fibers. Mineralization is therefore both spheritic and inotropic. Isolated flattened cells lie on the outer surface of the squamulae and seem to be involved in mineral deposition. Cells that line the basal plate synthesize the collagenous stroma of the plate. Each scale lies in a thin connective tissue pocket, and a large connective tissue pouch includes several scales in each annulus.The similarities of gymnophione scales to elasmoid scales of osteichthyans are largely superficial. Aspects of mineralization and of pocket development differ considerably. There are also similarities, as well as differences, in the gymnophione scales and osteoderms of amphibians and of reptiles. We consider that such dermal structures have arisen many times in diverse lineages of vertebrates, and that these are expressions of properties of dermal collagen to support mineralization by specialized dermal cells. However, we recommend that the term “dermal scale” be used for the mineralized dermal units of osteichthyans and gymnophiones, and “osteoderm” for the dermal structures of frogs and squamates, with the understanding that the terminology recognizes certain convergent attributes of shape and structure, but not of process.
    Additional Material: 36 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052060104
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  • 8
    Electronic Resource
    Electronic Resource
    Structure of the dermal scales in gymnophiona (Amphibia) (1980)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 165 (1980), S. 41-54 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histology and cytology of dermal scales of the gymnophionans Ichthyophis kohtaoensis and Hypogeophis rostratus reveal their structure and the nature of their mineralization.Dermal scales are small flat disks set in pockets in the transverse ridges of the skin. Each pocket contains several scales of various sizes. A ring of “hypomineralization” of varying diameter may occur on scales of a particular dermal pocket but bears no relation to the diameter of these scales.Three different layers form the scales and are seen on sections perpendicular to the surface. The cells of the basal layer lie deepest. Each of the two or three more superficial fibrous layers is composed of bundles of fibres that are oriented in parallel. The orientation varies among layers. The striation of the fiber scales has a periodicity comparable to that of the surrounding dermal fibers. Squamulae form a discontinuous layer on the scale surface and are the only mineralized part of the scale. The minerals are deposited both on the collagen fibers passing from the fibrous layers into the squamulae, and in the interfibrillar spaces. Spherical concretions, either isolated or coalescent, reaching up to 1 μm, are found on the surface of the squamulae.The dermal scales of Gymnophiona present some analogies with those of evolved bony fishes. Their characteristics could make them an original model for the study of mineralization.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051650105
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  • 9
    Electronic Resource
    Electronic Resource
    New data on the structure and the growth of the osteoderms in the reptile Anguis fragilis L. (Anguidae, Squamata) (1985)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 186 (1985), S. 327-342 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light and electron microscopy shows the osteoderms of Anguis fragilis to be small, flat disks located in the dermis along the adult trunk: microradiography established the extent of the mineralization.Each osteoderm coincides exactly with an epidermal fold forming the keratinized scales characteristic of the skin of reptiles.Sections perpendicular to the surface show two mineralized layers differing in histological and histochemical characteristics and in fine structure, although both contain collagen fibrils. The structure of each layer can be related to that of the surrounding dermis.The outer superficial layer located in the loose dermis contains few collagen bundles that form a discontinuous sheet at the upper surface of the osteoderms. This superficial layer appears to be constituted of units separated by furrows and is composed of woven fibered bone.The basal plate comprises stratified lamellae formed of parallel-oriented collagen fibrils; the fibrils of successive lamellae lie at right angles. The densely packed collagen fibrils of the basal plate are distributed similarly to those of the dense dermis within which it lies. This layer exhibits structural and histochemical characteristics of a lamellar bone.The presence of two different layers in the osteoderms of Anguis fragilis may reflect their mode of formation, which consists of the deposit of mineral crystals in the preexisting dermal tissue. This mineralization process, considered as a “metaplastic ossification,” may reflect the potentiality retained by the dermis of reptiles to form mineralized structures.
    Additional Material: 28 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051860309
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  • 10
    Electronic Resource
    Electronic Resource
    A family of efficient extrapolation formulae and their application in mechanics (1998)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 43 (1998), S. 733-753 
    Details
    ISSN: 0029-5981
    Keywords: extrapolation ; series ; sequences ; binomial power series ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The problem of extrapolation based just on a few initial terms of a sequence or series is discussed. Possible regularity of the extrapolation formula is postulated. Binomial power series is regarded as sufficiently regular and several extrapolation formulae using 3, 4, or 5 initial terms and based on binomial power series are derived. They are called the ‘bs-extrapolation formulae’ and compared to other extrapolation algorithms. Good accuracy in many particular cases is stated. Three examples of applications in mechanics are quoted: they consider consecutive FEM-solutions, postbuckling behaviour of an Euler column and optimal plastic design of a plane T-head. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 2 Ill.
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