Transverse circulation in the riparian region of turbulent channel flow
Transverse circulation in the riparian region of turbulent channel flow
O.N. Mel'nikova, Yu.G. Pyrkin, G.G. Khundzhua
On 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 AbstractInterpreting Mossbauer-experiment data
Interpreting Mossbauer-experiment data
E.N. Terent'ev
A method of automated interpretation of Mossbauer spectra is proposed, consisting in .lncrease in the spectral resolution with subsequent interpretation of the experimental data.
Show AbstractRecurrence relation for the vertex function in the ladder approximation
Recurrence relation for the vertex function in the ladder approximation
V.V. Belokurov, N.I. Usyukina
For the vertex function of scalar quantum field theory in the ladder approximation, a relation recurrent in the loop number is obtained.
Show Abstract"Extinction theorem." A quantum approach
"Extinction theorem." A quantum approach
V. Buzhek (Czechoslovakia), V.I. Grigor'ev, R. Khronek (Czechoslovakia)
The 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 AbstractInhomogeneous matching system for single-mode waveguides
Inhomogeneous matching system for single-mode waveguides
M.N. Zhitnikova, K.V. Chernyshev
The 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 AbstractEnergy migration in photosynthesis for various models of the organization of the light-collecting matrix
Energy migration in photosynthesis for various models of the organization of the light-collecting matrix
E.M. Melikhova, A.K. Kukushkin
The 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 AbstractTorsion-magnetometer investigation of films with a cylindrical magnetic domain structure
Torsion-magnetometer investigation of films with a cylindrical magnetic domain structure
L.M. Korenkova, T.N. Letova, I.M. Saraeva
Magnetization 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 AbstractMagnetic order-disorder transition in highly dilute ferrite-spinels
Magnetic order-disorder transition in highly dilute ferrite-spinels
K.P. Belov, A.N. Goryaga, A.I. Korokev
The 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 AbstractVertical distribution of the scattering properties of water in the active layer of the sea
Vertical distribution of the scattering properties of water in the active layer of the sea
G.P. Petrova, V.S. Solomatin, N.K. Shelkovnikov
Using 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 AbstractPara process in the ferrite MnFe$_2$O$_4$ at low temperatures
Para process in the ferrite MnFe$_2$O$_4$ at low temperatures
K.P. Belov, A.N. Goryaga, V.N. Pronin, L.A. Skipetrova
It 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.
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