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  • 1
    Electronic Resource
    Electronic Resource
    Semiclassical approximations in problems involving double-minimum potentials: A reply (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 5352-5353 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455584
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  • 2
    Electronic Resource
    Electronic Resource
    The interpretation of the neutron inelastic scattering and infrared absorption spectra of chromous acid using the double Morse potential model (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 3375-3380 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The neutron inelastic scattering and infrared absorption spectra of chromous acid are analyzed using a double Morse potential model. The proton tunneling frequency is assigned to a peak at 548 cm−1 and the ||0〉→||2〉 transition to the band at 2050 cm−1 in the neutron inelastic scattering spectrum. These assignments differ from those (viz. ||0〉→||1〉=226 cm−1, ||1〉→||2〉=1650 cm−1) made prior to the availability of the neutron inelastic scattering data. The proton tunneling frequency is thus assigned to a peak of considerably higher frequency. The model calculations also explain the infrared absorption spectrum of deuterated chromous acid and resolve previous discrepancies in the crystallographic data for chromous acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452980
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  • 3
    Electronic Resource
    Electronic Resource
    Geometrical models for the high-frequency dielectric properties of brine saturated sandstones (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 2575-2582 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the MHz–GHz range, geometrical effects associated with platy grains (e.g., clay particles in sandstones) are especially important in determining the complex dielectric function, ε(ω), of rocks. We consider two classes of geometrical models based on rather different pictures for the spatial arrangement of the clay particles. In the bimodal model, spherical and platy grains (with a single aspect ratio) are randomly dispersed throughout the system while in the coated grain consolidation model the platy grains are confined to a thin layer at the pore grain interface. Calculations based on these models are compared with experimental data on five sandstones and the coated grain solidation model is generally found to be in better agreement. In sandstones exhibiting the strongest frequency dependence in ε(ω), we find that a continuous distribution of platy grain aspect ratios is required to obtain a satisfactory fit to the experimental data. Such distributions are easily treated within the coated grain consolidation framework.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341645
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  • 4
    Electronic Resource
    Electronic Resource
    Interfacial transport in porous media: Application to dc electrical conductivity of mortars (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 5898-5908 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A mortar is a composite of inert sand grains surrounded by a porous cement paste matrix. We investigate the electrical conductivity of model mortars that include enhanced electrical conduction in the matrix–sand grain interfacial region. The electrical conductivity is evaluated by a combination of finite element, finite difference, and random walk methods for periodic and disordered models of mortar. Since the effective conductivity within the interfacial zone is often much higher than the bulk matrix conductivity, the qualitative features of transport in these systems is often controlled by the connectivity of the interfacial zone. Special attention is thus given to the geometrical percolation of this zone. A family of effective medium approximations give a good qualitative description of the disordered model's electrical properties. A simple four parameter Padé approximant is found to successfully describe the electrical conductivity of the periodic model over the entire range of parameters studied. Finally, we show that our calculations can be used to obtain a reasonable estimate of the permeability to viscous fluid flow. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360591
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  • 5
    Electronic Resource
    Electronic Resource
    Deep-level transient spectroscopy study of n-type GaAs epitaxial layers grown by close-spaced vapor transport (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1126-1129 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have done a deep-level transient spectroscopy study of deep donor traps existing in n-type GaAs epitaxial layers grown by close-spaced vapor transport. All the samples exhibited a bulk trap having an important concentration ((approximately-greater-than)1014 cm−3), which we have noted ELCS1 and identified with the trap EL12, which was observed in vapor-phase epitaxy materials. Other bulk traps were observed in some samples, but in a weaker concentration (∼1013 cm−3). In other samples, in addition to ELCS1, two more traps were seen; their concentration increased towards the surface. One of them is probably localized near the surface; the other one (ΔEa=0.83 eV, σna=0.8×10−13 cm2) must be identified with the donor trap EL2; it is also present in the bulk, but with a lower concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343049
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  • 6
    Electronic Resource
    Electronic Resource
    Ku-band radiation produced by a relativistic backward wave oscillator (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 1366-1378 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Reported in this paper are the results of an experiment to produce high-power Ku-band (12–18 GHz) microwave radiation from a backward wave oscillator (BWO) driven by a relativistic electron beam. Experimentally measured output power was about 250 MW at 12.5 GHz and 100 MW at 14 GHz. A description of the slow wave structure is given along with theoretical predictions of the vacuum waveguide dispersion relations. The diagnostics to determine the frequency and power of the device are described. Finally, comparisons between the experimentally measured frequency and power, and the analytic and numerical simulations of the BWO are made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336531
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  • 7
    Electronic Resource
    Electronic Resource
    Magnetic resonance, digital image analysis, and permeability of porous media (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1146-1148 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The results of an experimental and theoretical study of consolidated, acid-cleaned fused glass beads are presented. Measurements of the spin-lattice lifetime, permeability, and capillary pressure curves in conjunction with digital analysis of scanning electron microscope images and theoretical modeling lead to a description of this porous material consistent with the fast diffusion picture of nuclear magnetic relaxation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98766
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  • 8
    Electronic Resource
    Electronic Resource
    Image-based models of porous media: Application to Vycor glass and carbonate rocks (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3553-3555 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We develop a new class of three-dimensional geometrical models of porous media based on the smoothing of random white-noise images. With the appropriate choice of smoothing parameters, models of this kind are shown to provide reasonable representations of Vycor glass and crystalline dolomites. Transport and structural properties are found to be in accord with experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105630
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  • 9
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    Electrical and fluid transport in consolidated sphere packs (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-05-09
    Description: We calculate geometrical and transport properties (electrical conductivity, permeability, specific surface area, and surface conductivity) of a family of model granular porous media from an image based representation of its microstructure. The models are based on the packing described by Finney and cover a wide range of porosities. Finite difference methods are applied to solve for electrical conductivity and hydraulic permeability. Two image processing methods are used to identify the pore-grain interface and to test correlations linking permeability to electrical conductivity. A three phase conductivity model is developed to compute surface conductivity associated with the grain-pore interface. Our results compare well against empirical models over the entire porosity range studied. We conclude by examining the influence of image resolution on our calculations.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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