Structure and properties of TiC-TiNi composites alloyed with iron

The structure, composition, and mechanical properties of iron-alloyed TiC-TiNi composite materials are studied. When the titanium carbide framework is sintered with iron and then impregnated with titanium nickelide, iron atoms are found to diffuse into the matrix and form the B2 structure that is inhomogeneous (gradient) in chemical composition and properties and exhibits various temperatures of martensitic transformation. The latter fact shows up in the broadening of the martensitic transformation hysteresis and its shift toward low temperatures with increasing iron content. At room temperature, the strength properties of gradient-matrix TiC-TiNi composites are shown to increase with iron concentration.     

Modulation of the phase difference between polarization modes in single-mode fibers

Mechanisms of polarization modulation in a single-mode fiber that modulate the phase difference between polarization modes without affecting their amplitudes are considered. A coefficient that characterizes the efficiency of cylindrical piezoceramic modulators and is independent of their resonant properties is introduced. Analytical expressions for this coefficient for different modulation mechanisms are derived. The lateral pressure on the fiber is shown to provide the highest efficiency. For isotropic fibers, a modulator with a squeezing covering, which increases significantly its efficiency, is studied. For anisotropic fibers, the most appropriate way of phase difference modulation is longitudinal extension, in which case the birefringence axes do not have to be matched. In most cases, the measured and predicted efficiencies are in good correspondence.     

Stimulated raman scattering in fiber-optic communication lines

Stimulated Raman scattering (SRS) in a long-distance fiber-optic communication line with wavelength-division multiplexing (WDM) is studied theoretically at a high power of the signal transmitted. A new criterion for determining the SRS threshold is used to calculate the critical input power versus the number of optical channels and frequency separation between them. The theoretical model is verified experimentally. SRS interaction between two channels in a communication line with an SRS amplifier for which the optical waveguide of the line serves as a nonlinear medium is measured.     

Theory of magnetoelectric effect in double-layer ferromagnetic-piezoelectric structures

A theory of magnetoelectric effect in double-layer ferromagnetic-piezoelectric plate-shape structures is presented. Using the material and motion of continuum equations, an expression for the magnetic coefficient is derived in terms of the parameters characterizing the magnetic and piezoelectric phases. It is shown that in the region of electromagnetic resonance there is a considerable increase in the magnetoelectric coefficient value. A relationship is obtained between the ferromagnetic and piezoelectric thicknesses for which the magnetoelectric coefficient is maximal. The coefficients calculated for the structures based on permendure — plumbum zirconate-titanate are given, and the results of calculations are compared to the experimental data.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 3–6, December 2004.     

The Kapitza Effect in Charge-Ordered Layered Crystals

It is shown that the Kapitza effect in charge-ordered layered crystals can be explained for the case of a parallelism of magnetic field and measuring current when the Landau quantization and its effect on the charge-carrier scattering are considered. There is a linear correlation between the magnetic field and longitudinal resistance under the assumption that the scattering of charge carriers by acoustic phonons is dominant, and the band-to-band transitions are suppressed. The relations for the Kapitza coefficient are derived for different degrees of electron gas degeneracy and different values of interaction resulting in layered charge ordering.     

Addition to the Solution of the Problem on the Motion of a Free Nonrelativistic Electron in a Magnetic Field

In addition to the solution of the quantum mechanical problem on the motion of a free electron in a magnetic field, given by L. D. Landau in his pioneering work, this quantum mechanical problem is solved in view of the fact that the sum of the components of the free kinetic energy of an electron along two axes is a periodic quantity varying identically within the boundaries of every Landau energy level. This periodicity is a consequence of the quantized motion of an electron in a plane normal to the direction of the external magnetic field.