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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 14 (2002), S. 2578-2581 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we numerically investigate the motion of viscoelastic liquids passing through two-dimensional periodic arrays of cylindrical particles using the finite element method. The viscoelastic liquid is modeled by the Chilcott–Rallison version of the finitely extensible, nonlinear elastic (FENE) dumbbell model. The permeability and the viscoelastic stress distribution are studied as functions of the dimensionless relaxation time De and the dimensionless wave number kD, where k=2π/λ is the wave number, λ is the distance between the particles in the flow direction and D is the cylinder diameter. The porosity and D are held fixed. Our simulations show that for a fixed value of De the viscoelastic permeability increases with kD, but, as is the case for Newtonian fluid [Alcocer, Kumar, and Singh, Phys. Rev. E 59, 711 (1999)], this increase is not monotonic. The permeability decreases between kD(approximate)5.0, where it is locally maximum, and kD(approximate)7.7, where it is locally minimum. The difference between the locally maximum and minimum values of permeability increases with increasing De. When De=O(1) the locally minimum value of the permeability is ∼40% smaller than the value at the local maximum. This implies that a substantial change in permeability can be achieved by changing the distance between the particles in the flow direction while keeping De, D, and porosity fixed. © 2002 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 4325-4333 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of signal modulated optical radiation on the Schrödinger wave function has been studied in a quantum well in a n-AlGaAs/GaAs modulation doped field effect transistor (MODFET) and related device characteristics. Partial depletion of the active region of the modulation doped field effect transistor has been considered. At the heterojunction interface two different models for the quantum well has been assumed: (1) a triangular potential well and (2) a modified triangular potential well of finite depth. From the knowledge of frequency dependent Schrödinger wave function sheet concentration of the two-dimensional electron gas, the drain-source current of the MODFET and the transfer characteristics as a function of signal frequency have been evaluated. The frequency dependent current–voltage characteristics are compared with the published theoretical results since no experimental data are available on similar studies. © 2000 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3762-3764 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The analysis of experimental data of magnetomicrowave Kerr effect in MgMn ferrite samples at 9.442 GHz has been carried out using external permeability tensor components which take care of demagnetizing fields more accurately in the theory and is based on the guided wave propagation of the microwave inside the sample. The present analysis gives a better agreement with the experimental data in comparison to our earlier analysis which was based on the free-wave propagation of the microwave. The importance of the image effect in the demagnetizing factor is also discussed.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 4379-4381 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The voltage dependence of dc resistance of polycrystalline GdtY3−tFe5O12 (t=1.0, 1.1, 1.6, and 2.2) is experimentally studied at different temperatures. The data is explained on the basis of Krausse's theory. It is found that gadolinium substitution in YIG does not affect the grain-boundary potential barrier height (φ0). The temperature, however, affects φ0. The parameter z, in Krausse's model, which is found to be temperature independent, increases with the increase in the gadolinium substitution in YIG.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 4186-4188 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magneto microwave Kerr effect (MMKE) in the Voigt configuration is observed, for the first time, on two polycrystalline MgMn ferrite samples at x-band frequency. The experimental data are analyzed on the basis of the MMKE theory suitably modified for Voigt configuration Kerr effect. The values of effective linewidth have also been calculated.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 1404-1404 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 2793-2801 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper a comprehensive model of current conduction in polycrystalline silicon (polysilicon) based on the thermionic-emission-diffusion (TED) theory is developed, and on the basis of this model an expression for the effective majority carrier mobility μeff is derived. This expression is quite general in nature and some thermionic emission (TE) theory based expressions for μeff can be obtained from it straightaway under certain simplifying assumptions. In addition, it helps in understanding the physical significance of the scaling factor used by earlier workers to explain their experimental results. Also, the experimental data on Hall mobility, which we obtained under an ohmic conduction regime in the 300–440 K temperature range for dark and illuminated conditions in lightly doped n-type polysilicon samples of different grain sizes, are presented and are interpreted on the basis of the TED model. Under strong illumination, the Hall mobility μHL was observed to vary with temperature T according to the relation μHL=aT−b, where a depended on grain size and was found to be smaller for the smaller grain size. The dark mobility data fitted well into the TED-based expression for μeff considering the interface states associated with grain boundaries to be localized at Ev+0.63 eV in the band gap. The analysis reveals that, generally, the scaling factor is needed if the effect of diffusion is neglected in comparison with the thermionic emission while in essence it is appreciable to be considered. However, in the TED model, as diffusion contribution in controlling the current transport across the grain-boundary potential barrier is well taken care of, the scaling factor is not required.
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3780-3782 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electric, dielectric permittivity, loss tangent, microwave power absorption, and hysteresis loop parameters were studied on a series of cobalt-substituted lithium titanium ferrites. The experimental results indicate that cobalt substitution affect all these parameters. The observed dispersion in conductivity and dielectric permittivity with frequency and temperature are in accordance with Maxwell–Wagner model while the microwave and hysteresis loop properties can be interpreted with the help of Dionne's exchange isolation model.
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 692-695 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report field-effect measurements of the density-of-states (DOS) distribution in the last-deposited surface of undoped glow-discharge a-(Si,Ge):H alloy films containing up to 15% Ge. Over the energy range investigated (Ef≤E≤Ef+0.4 eV) the DOS exhibits a peak approximately 0.7 eV below Ec, and the total number of midgap states increases monotonically by a factor of 2 with Ge content. No structure specifically attributable to Ge defect states is seen. These results are interpreted in terms of a diphasic microstructural model of the alloy films.
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 3683-3685 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fine grain BaTiO3 thin films with a grain size ranging between 100 and 1000 A(ring) were deposited using the reactive partially ionized beam deposition technique at 550–600 °C. A metal/insulator/metal structure of these materials was fabricated and the dielectric response was measured up to 40 GHz using a network analyzer. It is shown that these films are not ferroelectric. However, these films show a dielectric relaxation in the frequency interval between several MHz and 1 GHz. We propose that this indicates a relaxation mechanism not related to the ferroelectric domain walls. © 1995 American Institute of Physics.
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