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  • 1
    Electronic Resource
    Electronic Resource
    Ritz approximations to two-dimensional boundary value problems (1971)
    Springer
    Numerische Mathematik 18 (1971), S. 171-181 
    Details
    ISSN: 0945-3245
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary Various Ritz solutions to the plane strain elasticity and the steady state heat flow boundary value problems for a polygonal domain Ω are considered. Historically, two basic approaches have been used in partitioning Ω into “finite elements”, (i) complete triangulation and (ii) rectangles with boundary triangles. In each case, the Ritz solution is the unique function (or vector of functions) which minimizes an energy functional over a finite dimensional vector spaceS. We consider as choices forS, piecewise linear and cubic functions for complete triangulations; and piecewise bilinear and bicubic functions for the case in which Ω is a union of rectangles and boundary triangles. For the elasticity problem,L 2 convergence of the components of stress and strain is established for each choice of the spaceS. L 2 convergence of the displacement vector is also shown for a wide class of boundary conditions. Convergence of the temperature is proven for the heat flow problem also. Numerical comparisons are made of the Ritz solutions based upon each spaceS of trial functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01436326
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  • 2
    Electronic Resource
    Electronic Resource
    Environmental Impacts of Industrial Energy Systems in the Coastal Zone (1978)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Environment and Resources 3 (1978), S. 395-475 
    Details
    ISSN: 0362-1626
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.eg.03.110178.002143
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  • 3
    Electronic Resource
    Electronic Resource
    Experimental configuration for isentropic compression of solids using pulsed magnetic loading (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 3587-3595 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A capability to produce quasi-isentropic compression of solids using pulsed magnetic loading on the Z accelerator has recently been developed and demonstrated [C. A. Hall, Phys. Plasmas 7, 2069 (2000)]. This technique allows planar, continuous compression of materials to stresses approaching 1.5 Mbar. In initial stages of development, the experimental configuration used a magnetically loaded material cup or disk as the sample of interest pressed into a conductor. This installation caused distortions that limited the ability to attach interferometer windows or other materials to the rear of the sample. In addition, magnetic pressure was not completely uniform over sample dimensions of interest. A new modular configuration is described that improves the uniformity of loading over the sample surface, allows materials to be easily attached to the magnetically loaded sample, and improves the quality of data obtained. Electromagnetic simulations of the magnetic field uniformity for this new configuration will also be presented. Comparisons between data on copper to ∼300 kbar using the old and new experimental configurations will also be made. Results indicate that to within experimental error, the configurations produce similar results in the pressure-volume plane. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1394178
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  • 4
    Electronic Resource
    Electronic Resource
    L ∞-convergence of collocation and galerkin approximations to linear two-point parabolic problems (1974)
    Springer
    Aequationes mathematicae 11 (1974), S. 230-249 
    Details
    ISSN: 1420-8903
    Keywords: 65N35 ; 65N30 ; 35K20 ; 39A35
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Two semidiscrete collocation approximations using smooth cubic splines are developed as approximations to the solution of two-point linear parabolic boundary value problems.L ∞-convergence results are presented for these two approximations as well as the piecewise linear Galerkin approximation. Several computational examples are given to illustrate the convergence results and demonstrate the applicability of the method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01834921
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  • 5
    Electronic Resource
    Electronic Resource
    Interaction of microwave radiation with Turkey sperm (1982)
    Springer
    Radiation and environmental biophysics 20 (1982), S. 145-152 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary Turkey sperm were exposed to 2.45 GHz microwave radiation in a temperature controlled waveguide apparatus. Temperature was maintained at 40.0 ± 0.5° C. The sperm were exposed for 30 min to a specific absorption rate (SAR) of 1, 10, or 50 mW/g. Before and following microwave exposure the following parameters were examined: percentage viability, percentage abnormal sperm, and release of the enzymes lactate hydrogenase (LDH) and glutamic oxalic transaminase (GOT). These parameters were not altered significantly by microwave exposure under the conditions tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323935
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  • 6
    Electronic Resource
    Electronic Resource
    A macro element approach to computing stress intensity factors for three dimensional structures (1979)
    Springer
    International journal of fracture 15 (1979), S. 231-245 
    Details
    ISSN: 1573-2673
    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: Résumé Une technique d'éléments finis à trois dimensions pour le calcul des facteurs d'intensité de contraintes est présentée. Une division en sous-structures est utilisée pour représenter la structure comme une chaîne d'éléments isoparamétriques à 20 noeuds, de telle manière qu'il soit possible d'isoler une région fissurée (ou suivant le cas de ramener à un problème de symétrie une portion de région fissurée) à l'aide d'un simple élément à 20 noeuds. Cette région fissurée est ensuite représentée par le moyen de macro-éléments contenant à priori une haute densité de noeuds au voisinage du front de fissures et qui est compatible avec l'élément standard à 20 noeuds, auquel il aboutit. On ne fait pas appel à des éléments singuliers spéciaux et virtuellement toute géométrie tridimensionnelle de forme arbitraire peut être prise en considération. Pour calculer le facteur d'intensité des contraintes, on recourt à la technique de dérivation de la matrice de rigidité. Les résultats numériques dans le cas d'une plaque fissurée soutiennent bien la comparaison avec les résultats publiés.
    Notes: Abstract A three dimensional finite element technique for calculating stress intensity factors is presented. Sub-structuring is used to model the structure as a catenation of 20-node isoparametric elements so as to isolate a crack region (or depending on problem symmetries a portion of a crack region) by a simple 20 node element. This crack region is then modelled by means of a macro element which contains, a priori, a high density of nodes in the vicinity of the crack front and is compatible with the standard 20 node elements that it abutts. No special singular elements are used and virtually arbitrary three dimensional geometries can be accommodated. The stiffness derivative technique is used to compute the stress intensity factor. Numerical results for a cracked plate compare well with published results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033222
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  • 7
    Electronic Resource
    Electronic Resource
    Pattern and change of a boreal forest landscape in northeastern China (1995)
    Springer
    Water, air & soil pollution 82 (1995), S. 465-476 
    Details
    ISSN: 1573-2932
    Keywords: boreal forest ; China ; deforestation ; fragmentation ; landscape pattern ; patch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We have studied the spatial and temporal patterns of a boreal forest landscape in northeastern China using aerial photographs from 1955 (before logging) through 1980. The primary forest landscape is a complex mosaic of four tree species, and three age classes for each tree species, for a total of eighteen patch types. In addition, the complexity of the primary forest landscape shows great variation in the number, size and areal composition of patches. The forest landscape has been fragmented obviously by deforestation. There is an average increase in patch number from 291.6 to 438.0 patches per 10 000 ha, and an average decrease in patch size from 34.3 to 22.8 ha. Most of the logged areas are small in size, an average of 10.9 ha. The areal composition of different patch types has been changed greatly since the 1950s. The hardwood forest areas (especially) have increased significantly (p=0.05); coniferousLarix gmelinii decreased significantly (p=0.05), andPinus sylvestris var.mongolica remained about the same. The area of old-age class in the dominant species,Larix gmelinii, has decreased significantly (p=0.05). In addition, young and middle age classes of all tree species occupy a larger proportion of the area in 1980 than in 1955. Due to deforestation and recovery, therefore, many of these ecosystems are in early succession stages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01182856
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  • 8
    Electronic Resource
    Electronic Resource
    On a network method for unsteady incompressible fluid flow on triangular grids (1992)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 15 (1992), S. 1383-1406 
    Details
    ISSN: 0271-2091
    Keywords: Incompressible flow ; Co-volume method ; Upwind ; Voronoi tessellation ; Networks ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The dual variable method for Delaunay triangulations is a network-theoretic method that transforms a set of primitive variable finite difference or finite element equations for incompressible flow into an equivalent system which is one-fifth the size of the original. Additionally, it eliminates the pressures from the system and produces velocities that are exactly discretely divergence-free. In this paper new discretizations of the convection term are presented for Delaunay triangulations, the dual variable method is extended to tessellations that contain obstacles, and an efficient algorithm for the solution of the dual variable system is described.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650151203
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of in vitro microwave radiation on the fertilizing capacity of turkey sperm (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 4 (1983), S. 43-54 
    Details
    ISSN: 0197-8462
    Keywords: microwave radiation ; fertilizing capacity ; turkey sperm ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Turkey sperm were exposed to 2.45-GHz microwave radiation in a temperature-controlled waveguide apparatus. Temperature was maintained at either 25 or 40.5 °C. The sperm were exposed for 30 min at a specific absorption rate (SAR) of 10 or 50 mW/g. Following irradiation, the sperm were used to inseminate virgin turkey hens artificially. During the 9 weeks following the single insemination, the following were assessed: mean number of eggs, percentage of fertile eggs, rate of decrease in egg fertility, percentage of hatched eggs, and percentage of early and late deaths. These data demonstrate that, for the conditions used in these experiments, microwave radiation has no effect on the fertilizing capacity of turkey sperm.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250040105
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  • 10
    Electronic Resource
    Electronic Resource
    A CHARACTERISTIC-LIKE METHOD FOR THERMALLY EXPANDABLE FLOW ON UNSTRUCTURED TRIANGULAR GRIDS (1996)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 22 (1996), S. 731-754 
    Details
    ISSN: 0271-2091
    Keywords: thermally expandable flow ; covolume method ; characteristic curve ; Delaunay tessellation ; dual variable method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Finite-difference-like discretizations are developed for the time-dependent Navier-Stokes equations and the thermal energy equation on Delaunay triangulations of the flow domain. The flow is assumed to be thermally expandable; that is, the density varies only with temperature. A characteristic- like (CL) method is used to discretize the temporal and convective terms. The dual variable method reduces the size of the discrete system by a factor of five.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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