Processes in an active layer distinguished by an intimate relation between wave and vibrational phenomena, a field structure that is not fixed, and a variable spectrum are investigated experimentally using an active resonant radio frequency transmission line. Conditions of active-layer emission, mutual and induced synchronization of the autogenerators, and the amplification of the external signal are considered. The experimental data are in agreement with the results of numerical modeling of the processes.
Show AbstractOn the basis of an experimental determination of the three components of the instantaneous-velocity vector in the cross section of turbulent channel flow and analysis of the Reynolds equation, the transverse circulation of liquid in the riparian region of the channel flow is analytically investigated.
Show AbstractA method of automated interpretation of Mossbauer spectra is proposed, consisting in .lncrease in the spectral resolution with subsequent interpretation of the experimental data.
Show AbstractThe method of low-temperature X-ray diffractometry is used to study the crystalline structure of the intermetallide TbFe$_2$ in the magnetically ordered state. It is established that the intermetallide TbFe$_2$ has a rhombohedral structure in the temperature range 5-295 K (spatial group $D_{3d}^{5}$). In the elementary cell of the intermetallide TbFe$_2$ , the terbium atoms occupy the positions 2(c) with coordinates 3/8 + x, 3/8 + x, 3/8 + x and 5/8 - x, 5/8 - x, 5/8 - x. The values of the parameter x are determined, and its dependence on the temperature in the range 5-295 K is studied. Displacement of terbium atoms toward each other along the direction <111> is observed experimentally on cooling from 295 to 5 K.
Show AbstractFor the vertex function of scalar quantum field theory in the ladder approximation, a relation recurrent in the loop number is obtained.
Show AbstractThe evolution of a single-photon packet in a cubic ideal crystal of motionless two-level centers is investigated. It is shown that complete "extinction" of the initial packet by some of the secondary radiation always occurs. For the given quantum-field model, an accurate solution is found, and the long-wave approximation is analyzed in more detail.
Show AbstractThe problem of single-frequency matching of two solid rod waveguides of different cross section for minimum reflection coefficient is considered. Matching may be achieved using a rod of constant cross section, of length $l_0=\lambda _{0}(2n +1)/4$, and of area $S_0=(\rho _{1},c_1,\rho _{2}c_2S_1S_2/\rho ^2c^2)^{1/2}$. If the form of the matching rod is close to cylindrical, the controlling function may be written in the for·m of a linear expression in terms of the small parameter $\Delta = k_0\Delta _x + l_0\Delta _{k}:\tilde{u}_{\Delta} (x)=\Delta \cdot \tilde{u}_1 (x)$, where $k_0 = 2\pi / \lambda _0$. The continuous function $\tilde{u}_1 (x)$ is represented by the polynomial $\sum_{i=0}^{N} a_i x^i$, and N = 2 is chosen. As an example, the matching of rods with an area ratio $S_1 : S_2 = 1:10$ by means of a quarter-wave cylindrical wave and rods of varying cross section is considered.
Show AbstractThe number of excitational jumps over a grid before capture by a trap is calculated for cylindrical lattices of different dimensions modeling a light-collecting pigment matrix. It is shown that the influence of the form of the lattice on the number of excitational jumps before capture by a trap is most clearly expressed when the lattice dimensions are not very large (with M < 100 light collectors). The importance of this conclusion is clear in that the number of light collectors is no more than 50 in some investigations of pigment-protein complexes.
Show AbstractMagnetization processes of films with a cylindrjcal magnetic domain structure are investigated, and a torsional method of measuring the saturation magnetization M$_s$ of these films is discussed. Results of torsion-magnetometer measurements of the induced-anisotropy constant and saturation magnetization of films of ferrite-garnets of various compositions are given.
Show AbstractThe character of the magnetic transition in three samples of dilute ferrites with the spinel structure is studied: Li$_{0.2}$Zn$_{0.6}$Fe$_{2.2}$O$_4$(Li-Zn), Mg$_{1.5}$FeTi$_{0.5}$O$_4$(Mg-Ti), and Ni$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$(Ni-Zn). According to Mossbauer investigations, not only ordered but also disordered spins are present in the first two samples (mictomagnetism), while all the 3d cations are magnetically active in the Ni-Zn sample. Values of the Curie temperature and spontaneous magnetization are determined from the dependence of $\frac{H}{\sigma}(\sigma ^2)$. It is established that in samples including magnetically inactive ions either the relations $(\sigma_s / \sigma_{s_0}^2 = \xi (1-T/\Theta)$ is not satisfied (the Mg-Ti sample has a linear dependence of $\sigma _s/\sigma$ on $T/\Theta$) or the coefficient in the Li-Zn sample is considerably smaller than in the Ni-Zn sample. It is found that it is only in dilute Mg-Ti ferrite that the displacement of the maximum on the curve of ${\left | \chi _{dif} \right |}_{H=const}(T)$ with increase in field $H$ occurs in the direction of lower temperatures, i.e., as in material with ordering of "spin-glass" type. It is concluded that transition from a paramagnetic to a noncollinear ferromagnetic state may occur in dilute ferrites.
Show AbstractUsing a laboratory apparatus which allows the relative intensity of scattered light to be measured at scattering angles of 90° and close to 0°, the optical properties of sea water in various regions of the Mediterranean Sea and the Atlantic Ocean were studied. The profiles of the vertical distribution of the relative light-scattering coefficient and temperature in the given regions correlate with one another.
Show AbstractIt is shown that, in the ferrite MnFeO$_4$ below 240 K, the para process (increase in the true magnetization in strong magnetic fields) is associated with de localization of electrons in the covalent bonds $Mn_{B}^{2+}-Mn_{B}^{2+}$ and $Fe_{B}^{3+}-Fe_{B}^{3+}$. An external magnetic field compressing the 3d shell of the cations breaks the covalent bonds, which leads to disruption of spin pairing in these bonds, and hence to increase in magnetic moment of the cations Mn$_{B}^{2+}$ and Fe$_{B}^{3+}$ in an octahedral sublattice, which is responsible for the magnetic moment in Mn ferrite. It is suggested that the underestimated experimental value of the magnetic moment $n_0$ at the absolute zero in Mn ferrite is basically due to spin pairing of the electrons localized at covalent bonds between cations B.
Show AbstractWithin the framework of the five-dimensional theory of gravitation, electromagnetism, and scalar field, by means of additional space-time measurements, mass formulas describing the mass spectrum of all presently known mesons with high accuracy are obtained.
Show AbstractTheorems of existence in the small and uniqueness of the generalized solution are proven for a one-dimensional system of Vlasov equations, with the condition of absorption for the distribution function at the ends of the interval.
Show AbstractThe dependence of the amplitude and phase of light in the zero order of diffraction on the amplitude of the acoustic wave and the angle of incidence of the light on the interaction region is investigated. The features of the passage of a spatially modulated light wave through an acoustic field are considered. The nonreciporcal effect is investigated.
Show AbstractOn the basis of the addition theorem for generalized spherical functions, the transition matrix for Laplace-series coefficients in rotations of a spherical coordinate system is determined, and the invariance of the normalized exponential dispersion in such a rotation is proven.
Show AbstractThe generational and spectral characteristics of mixed solutions of Rhodamine dyes and oxazine 17 are given, as a function of the concentration of donor and acceptor components and the solvent composition with lamp pumping. Change in these characteristics is associated with the influence of inhomogeneous broadening of the energy states of dye molecules and intercombinational transitions to triplet levels.
Show AbstractThe specific heat of four compounds Fe$_x$Co$_{1-x}$Cl$_2$ is measured in the concentration range x = 0-0.6 and the temperature range 2-27. In these compounds, in which the initial components are laminar antiferromagnets with strong competing anisotropy, the phase diagram and the features of the laws of spin-wave dispersion are investigated.
Show AbstractThe distribution of the magnetization in a plane-parallel layer of a uniaxial ferromagnetic after an orientational phase transition from a state with homogeneous magnetization to a state with a band domain structure accompanying a change in an inclined external field is calculated.
Show AbstractThe spectral parameters of a self-oscillatory system with a resonant circuit of finite mechanical rigidity under the action of natural fluctuations are investigated. It is shown that, in such autogenerators, depending on the self-oscillation power, the spectral characteristics may differ significantly from the traditional form; the generation lines are considerably broadened here, and regions of considerable intensity appear in the spectra of amplitude and frequency fluctuations; in real conditions, this leads to significant reduction in stability of the self-oscillation frequency.
Show AbstractIt is shown that, in conditions of weak localization, the correlational contribution to the conductivity of two-dimensional disordered systems may be proportional to ln$T$ or $p\text{ln}T$, depending on which predominates: the temperature broadening or the inelastic damping.
Show AbstractThe dependence of the shock-ionization rate g on the electric field strength is obtained for the $n$-type alloy Hg$_{0.80}$Cd$_{0.20}$Te at temperatures T = 4.2 and 77 K. It is established that $g$ decreases with increase in temperature. At T = 4.2 K, nonmonotonic variation in $g$ is observed in a longitudinal magnetic field: the initial increase is replaced by a drop.
Show AbstractIt is shown that the region of applicability of the double logarithmic asymptote of the mass operator has an upper bound. In the rainbow-diagram approximation, the true asymptote beyond the limits of this region is found.
Show AbstractThe frequency characteristics of a Thomson generator coupled inductively to a resonance loop of frequency close to a harmonic frequency are investigated theoretically and experimentally. It is shown that the character of the frequency dependence is different for tying at the harmonic frequency and at the fundamental tone; the difference corresponds to an additional phase shift of $\pi/2$. Some mechanisms leading to asymmetry of the frequency curve are considered.
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