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  • Artikel: DFG Deutsche Nationallizenzen  (13)
  • 1990-1994  (13)
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5791-5791 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Near-field scanning optical microscopy (NSOM) has been used to image and record domains in thin-film magneto-optic (MO) materials (e.g., a Co/Pt multilayer). In this technique, a subwavelength-sized source or detector of visible light is placed in close proximity to a sample and raster scanned to read or write data on a scale inaccessible to traditional lens based systems. The technique, therefore, represents a hybridization of conventional magnetic and MO storage technologies. In the imaging mode, resolution of 30–50 nm has been consistently obtained, whereas in the recording mode, domains down to −60 nm have been written reproducibly. Data densities of −45 Gbits/in.2 have been achieved, well in excess of current magnetic and MO methods. A brief analysis of speed and other issues indicates that the technique may represent a viable alternative to these and other methods for anticipated high density data storage needs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3698-3708 
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Departures from thermal (translational), ionization, and excitation equilibrium in an axisymmetric argon plasma jet have been studied by two-dimensional numerical simulations. Electrons, ions, and excited and ground states of neutral atoms are represented as separate chemical species in the mixture. Transitions between excited states, as well as ionization/recombination reactions due to both collisional and radiative processes, are treated as separate chemical reactions. Resonance radiation transport is represented using Holstein escape factors to simulate both the optically thin and optically thick limits. The optically thin calculation showed significant underpopulation of excited species in the upstream part of the jet core, whereas in the optically thick calculation this region remains close to local thermodynamic equilibrium, consistent with previous experimental observations. Resonance radiation absorption is therefore an important effect. The optically thick calculation results also show overpopulations (relative to equilibrium) of excited species and electron densities in the fringes and downstream part of the jet core. In these regions, however, the electrons and ions are essentially in partial local thermodynamic equilibrium with the excited state at the electron temperature, even though the ionized and excited states are no longer in equilibrium with the ground state. Departures from partial local thermodynamic equilibrium are observed in the outer fringes and far downstream part of the jet. These results are interpreted in terms of the local relative time scales for the various physical and chemical processes occurring in the plasma.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 142-144 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Near-field scanning optical microscopy (NSOM) has been used to image and record domains in thin-film magneto-optic (MO) materials. In the imaging mode, resolution of 30–50 nm has been consistently obtained, whereas in the recording mode, domains down to ∼60 nm have been written reproducibly. Data densities of ∼45 Gbits/in.2 have been achieved, well in excess of current magnetic or MO technologies. A brief analysis of speed and other issues indicates that the technique may represent a viable alternative to these and other methods for anticipated high density data storage needs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 129 (1993), S. 0 
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 1432-1084
    Schlagwort(e): Mammography ; Phosphor plates ; Modulation transfer function ; Image contrast
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Mammography and accurate microcalcification detection require very good spatial resolution. We have compared the diagnostic capabilities of reduced-exposure, third-generation, 5 cycles/mm computed radiography (CR) phosphor plates with conventional screen-film in 67 patients. No difference in diagnostic accuracy was detected. The digital characteristics of storage phosphor plates erabled us to study the relationship between contrast and spatial resolution. We developed a computer program to identify a single 100 μm pixel in a digital image and assign various gray levels to that pixel. Using this model, we determined that, for our 5 cycles/mm CR system, the imaged contrast of a 100 μm object was 62% of the original contrast. Current 5 cycles/mm phosphor plate systems cannot adequately detect microcalcifications that approximate 100 μm or smaller unless a magnification technique is used.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Plasma chemistry and plasma processing 10 (1990), S. 473-491 
    ISSN: 1572-8986
    Schlagwort(e): Low-pressure ; ionization (chemical) nonequilibrium ; twotemperature ; plasma jets
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Technik allgemein
    Notizen: Abstract This paper presents a modeling attempt related to low-pressure plasma spraying processes which find increasing applications for materials processing. After a review of the various models for ionization and recombination processes, a two-temperature model for argon plasmas in chemical (ionization) nonequilibrium is established using finite rate chemistry. Results of sample calculations manifest departures from kinetic as well as chemical equilibrium, demonstrating that the conventional models based on the LTE (local thermodynamic equilibrium) assumption cannot provide proper prediction for low-pressure plasma jets.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Plasma chemistry and plasma processing 10 (1990), S. 493-500 
    ISSN: 1572-8986
    Schlagwort(e): Low-pressure ; ionization (chemical) nonequilibrium ; twotemperature ; plasma jets ; k-ε turbulence model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Technik allgemein
    Notizen: Abstract The nonequilibrium behavior of low-pressure, turbulent plasma jets has been tested using the k-ε turbulence model and the model described in the previous paper. It also has been shown that nonequilibrium effects cannot be excluded in the case of turbulent jets.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Plasma chemistry and plasma processing 11 (1991), S. 395-402 
    ISSN: 1572-8986
    Schlagwort(e): Diffusion ; ambipolar diffusion ; multicomponent plasmas
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Technik allgemein
    Notizen: Abstract A recently described self-consistent effective binary diffusion approximation is applied to ambipolar diffusion in a neutral multicomponent plasma in zero magnetic field, where forced diffusion due to the electric field E plays an essential role. The field E is determined by the constraint that the net current flow produced by the diffusion fluxes must be zero. The resulting effective binary diffusion fluxes are the sum of those that would obtain for E=0 and ambipolar correction terms proportional to E. The formulation is .self=consistent with respect to both mass and charge, the net diffusional fluxes of which are both identically zero. The results may be further simplified due to the small mass of the electrons. The effective binary diffusivity De of the electrons no longer appears in the simplified expressions. They are therefore well suited to numerical calculations, where the large value of De, might otherwise have resulted in unacceptable stability or accuracy restrictions. The well-known effective doubling of ion diffusivities due to ambipolar diffusion occurs in simple situations but is not a general feature.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Plasma chemistry and plasma processing 12 (1992), S. 299-325 
    ISSN: 1572-8986
    Schlagwort(e): Thermal plasmas ; plasma processing ; rnulticomponent ; chemistry ; diffusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Technik allgemein
    Notizen: Abstract A comprehensive computational model has been developed Jbr flowing thermal plasmas in the absence of electromagnetic fields, with particular emphasis on plasma jets. The plasma is represented as a rnulticomponent chemicalh, reacting ideal gas with temperature-dependent thermodynamic and transport properties. The plasma flow is governed by the transient compressible Navier-Stokes equations in two or three space dimensions. Turbulence is represented by subgrid-scale and k-ε models. Species diffusion is calculated by an effective binary diffusion approximation, generalized to allow /or ambipolar diffusion of charged species. Ionization, dissociation, recombination, and other chemical reactions are computed by general kinetic and equilibrium chemistry algorithms. Radiation heat loss is currently modeled as a temperature-dependent energy sink. Finite-difference approximations to the governing equations are solved on a rectangular spatial mesh using explicit temporal differencing. Computational inefficiency at low Mach number is avoided br reducing the effective sound speed. The overall computational model is embodied in a new computer code called LAVA. Computational results and comparisons with experimental data are presented Jbr LAVA simulations of a steady-stare axisymmetric argon plasma jet flowing into cold argon.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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