Quantitative method for determination of fibre texture in wires I. Principle of method and analytical expression of absorption factor

An X-ray diffraction method is described for the quantitative determination of the fibre texture in cylindrical specimens (wires), which does not require specimen preparation. The integrated intensity of the diffracted radiation from a certain atomic plane is measured in the direction parallel to the plane determined by the axis of the wire and by the direct beam for different orientations of the axis of the wire. These measurements can be carried out in practice using an X-ray counter diffractometer or Weissenberg goniometer. The pole figure is determined from the dependence of the diffracted intensity on the orientation of the wire after correcting the intensities for the absorption of radiation in the specimen. The geometric arrangement enables the absorption factor to be calculated analytically. Its form was verified experimentally by measuring the dependence of the intensity of the 220 reflection on the orientation of the axis of a cylindrical specimen of Al containing randomly oriented crystals.

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The author wishes to thank Z. iký for help in carrying out the measurements and calculations.     

Vapour—liquid equilibrium in binary systems formed by acetonitrile, 2-butanone and 1,2-dichloroethane

Isothermal vapour—liquid equilibria have been determined for 2-butanone + acetonitrile at 333.67 K, and for 2-butanone + 1,2-dichloroethane and acetonitrile + 1,2-dichloroethane at 333.15 K using a dynamic method. The apparatus used in these studies for the precise measurement of complete vapour—liquid equilibrium data is described and the reliability and accuracy of the measured data are considered in terms of the activity coefficients and of the dependences of the molar excess Gibbs energies on composition. Experimental inaccuracies are estimated for statistical treatment of the data both in terms of correlations and in consistency tests.     

Dynamic magnification of the galitzin seismograph excited by shock motion of the ground

A reduced dynamic magnification of the first maximum is derived for the seismograph of B. B. Galitzin during shock motion of the ground represented by the expressionAt ³e^– t     

The crystal structure of ammonium metavanadate

The paper deals with the structure analysis of ammonium metavanadate NH₄VO₃ from photographs obtained with a Weissenberg goniometer using CnKand MoKradiation. The dimensions of the orthorhombic unit cell determined from these photographs of the rotating crystal are a=4.92, b=11.82, c==5.85 Å. A satisfactory space group is Pbcm (D _2h ¹¹ ),with four molecules in the unit cell. The positions of the atoms in the unit cell were determined by means of the Patterson functions P(v, w), P(u, v) and from the projection of the electron density on the (001)plane. An analogy was found with the structure of the metasilicates from the pyroxen group. The oxygen atoms are coordinated tetrahedrally around the vanadium atoms. The tetrahedra VO₄ form infinite chains in the direction of the [001]axis. The VO₄ chains are mutually bonded by means of electrostatic bonds of the NH₄ ions. The splitting of the chains in an aqueous solution is connected with the dissociating and catalytic properties of the ammonium metavanadate.In conclusion we should like to thank the management of the Institute of Technical Physics of the Czechoslovak Academy of Sciences for enabling us to work on this problem.     

Atoms in Boolean powers

We show that the Boolean power of an orthomodular latticeL is atomic if and only if bothL and the underlying Boolean algebraB are atomic. We describe the set of all atoms in the Boolean power.     

One-parameter imbedding techniques for the solution of nonlinear boundary-value problems

A powerful numerical tool for the solution of nonlinear boundary-value problems —the one-parameter imbedding technique—is suggested. The basic principle is more than twenty years old; however, its numerical utilization has had only a few restricted applications up until recent times. The methods are divided into two categories: one- and multi-loop techniques. It is shown that the multi-loop techniques are of correct and incorrect type. Based on correct procedures new iteration techniques may be developed. Numerical solutions of differential equations arising for the one-parameter imbedding methods are presented along with the corresponding iteration techniques. Some typical imbedding procedures are discussed, and practical application of the method is demonstrated on calculated examples.