A simple method for the preparation of sodium and potassium aluminium hydrides

Summary Sodium and potassium aluminium hydrides are readily obtained from aluminium chloride and sodium and potassium hydrides, respectively, using organoaluminium compounds as catalysts for the reaction.     

Optical detection of an electric field in a GaAs/AlGaAs <Emphasis Type="Italic">n</Emphasis>-<Emphasis Type="Italic">i</Emphasis>-<Emphasis Type="Italic">n</Emphasis> heterostructure with double quantum wells

Processes occurring when a static transverse electric field is applied to a GaAs/AlGaAs n-i-n heterostructure with single quantum wells and asymmetric tunnel-coupled double quantum wells have been investigated by optical methods. The difference between the energies of exciton transitions for quantum wells of different widths makes it possible to attribute the observed photoluminescence peaks to particular pairs of wells or particular single quantum wells. The local electric field for each quantum well has been determined in terms of the Stark shift and splitting of exciton lines in a wide range of external voltage. A qualitative model has been proposed to explain the nonmonotonic distribution of the electric field over the depth of the heterostructure.     

Two-dimensional problem concerning the impact of a rigid body onto a thin elastic plate lying on the surface of a compressible fluid

Institute of Mechanics, Academy of Sciences of the UkrSSR, Kiev. Kiev Autorail Institute. Translated from Prikladnaya Mekhanika, Vol. 27, No. 9, pp. 59–66, September, 1991.     

Stability of cylindrical ribbed shells affected by compound loading

Methods of stability analysis for unsupported shells affected by compound loading have been expounded quite thoroughly in the literature [1, 2, 5–7]. In this case both the homogeneous, membrane subcritical state [1, 2, 5] as well as the inhomogeneous moment state [6] are considered. The homogeneous membrane subcritical state assumption [5, 6] is employed in the analysis of ribbed shells. The critical loads are found from equations of mixed-type.Timoshenko Institute of Mechanics, Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 30, No. 1, pp. 33–37, January, 1994.     

Reduced-Stiffness Method in the Theory of Shells

The fundamentals of the reduced-stiffness method, which is used in buckling analysis of reinforced and perfect and imperfect nonreinforced shells, are set out. The method is validated analytically and experimentally. The lower bound determined by this method is very close to the experimental lower bound. Some aspects of the current state and prospects for development and generalization of the method are discussed     

Functional approach to the periodic Anderson model

The method of functional integration is applied to the study of the behavior of the electron subsystem of adsorbed films with a regular structure. The effective action functional is calculated; equations for its parameters have been derived and investigated.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova, Akademii Nauk SSSR, Vol. 180, pp. 44–52, 1990.