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  • 1
    Electronic Resource
    Electronic Resource
    Low-threshold GaAs/AlGaAs lasers grown on Si by organometallic vapor phase epitaxy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 1114-1115 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-threshold double-heterostructure ridge-waveguide lasers have been fabricated in GaAs/AlGaAs layers grown on Si by organometallic vapor phase epitaxy. The pulsed threshold current of the best ridge-waveguide laser is 50 mA, with differential quantum efficiency of about 9% per facet. Broad-area lasers fabricated on the same wafer have pulsed threshold current densities as low as 300 A/cm2 .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99178
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  • 2
    Electronic Resource
    Electronic Resource
    On the steady simple shear flows of the one-mode Giesekus fluid (1989)
    Springer
    Rheologica acta 28 (1989), S. 13-24 
    Details
    ISSN: 1435-1528
    Keywords: One-modeGiesekus model ; mobility parameter ; Weissenberg number ; Couette flow ; Poiseuille flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Analytical solutions for the plane Couette flow and the plane Poiseuille flow of the one-mode Giesekus fluid without any retardation time have been obtained by considering the domain of definition for each of the two branch solutions which arise due to the presence of the quadratic stress terms in the constitutive equations. For each fixed value of the mobility parametera, the limiting value of the Weissenberg number for the upper branch solution, i.e., the physically realistic solution is determined in terms of the corresponding dimensionless shear stress for the plane Couette flow and in terms of the corresponding dimensionless pressure gradient for the plane Poiseuille flow. In the case of the plane Couette flow, it is shown that fora falling in the range 0≤a≤1/2 only the physically realistic solution exists while for 1/2〈a ≤1 a nonphysical solution coexists with the realistic one. In the case of the plane Poiseuille flow, it is shown that the non-physical solution cannot even exist around the center plane of the channel, and the effects of the mobility parameter and the dimensionless pressure gradient on the flow variables are investigated. Possible extensions of the present approach to other steady simple shear flows with and without the introduction of the retardation time are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01354764
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Zinc electrodeposit morphology under conditions of fluctuating current density (1987)
    Springer
    Journal of applied electrochemistry 17 (1987), S. 91-103 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Previous investigations have shown that particles within a fluidized bed electrode undergo rapid fluctuations in overpotential. This investigation is concerned with the effects of such fluctuations on zinc electrodeposit morphology. Both a fluidized bed electrode and a rotating disc electrode were used, with the latter being driven at either constant or fluctuating current density. The effect of the fluctuations on the morphology of 1-h deposits for neutral and acidic sulphate electrolytes was determined by examination under the scanning electron microscope. Both pure electrolytes and those containing additives (nickel, cobalt, antimony and a commercially available glue) were employed. Wide variation in microstructure was observed with the fluctuations having a marked effect. These results are partly explicable in terms of differing nucleating and growth rates of zinc crystallites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01009135
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  • 4
    Electronic Resource
    Electronic Resource
    Macrocrack interaction with transverse array of microcracks (1988)
    Springer
    International journal of fracture 36 (1988), S. 15-26 
    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 On envisage une formulation générale du problème d'une microfissure se propageant dans une zone où préexistent des microfissures. On se base, pour ce faire, sur une solution simultanée à un système d'intégrales singulières. Diverses méthodes décrites dans la littérature sont passées en revue de manière détaillée, et comparées à l'approche adoptée. Le problème spécifique considéré est celui d'une macrofissure s'approchant d'un “banc” de microfissures transversales, et les résultats sont applicables à l'interprétation des mécanismes de renforcement de la ténacité en présence de microfissures. Ces résultats illustrent les effets différents qui peuvent avoir les types de mise en charge sur le comportement de matériaux comportant des distributions de microfissures transversales ou des empilements de microfissures. La comparaison des résultats numériques avec les données récemment publiées fait apparaitre l'importance de l'exactitude du schéma numérique adopté. En se comparant à certaines données publiées [6], les résultats obtenus se révèlent divergents dans certains cas.
    Notes: Abstract General formulation of a problem involving a macrocrack propagating through an area with microcracks is considered. The applied approach is based on the simultaneous solution of a system of singular integral equations. Several methods described in the literature are discussed in detail and compared with our approach. The specific problem considered represents a macrocrack approaching an infinite transverse array of microcracks. Results can be used for interpretation of the microcrack-toughening mechanisms. Results illustrate the different effects due to loading types in materials with transverse microcrack arrays (stacks of microcracks). Numerical results are compared with data recently appearing in literature and they demonstrate the importance of the accuracy of the numerical scheme employed. Our results differ by a factor in certain cases as compared with data given in [6].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034814
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    Paper (German National Licenses)
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