Control of small phase arrays to form a prescribed amplitude-phase distribution

Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 9, pp. 1132–1136, September, 1989.     

Low-frequency internal friction in complex composite strands

Conclusion A method was proposed which makes it possible to study the low-frequency internal friction of complex fibers. This method was used to study the internal friction of complex composite fibers based on PCA and PE. We observed a relaxation process which is typical of the composite and is absent in the pure materials.Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 11–15, January–February, 1989.     

Effect of rare-earth oxides on the magnetic properties of anisotropic barium ferrites

The effect of rare-earth oxides on the properties of anisotropic barium ferrites has been studied by x-ray structural and Mössbauer methods. Additions of SrCO₃, as well as SrCO₃ and La₂O₃, SrCO₃ and Pr₆O₁₁, SrCO₃ and Nd₂O₃, SrCO₃ and Sm₂O₃ in amounts of 7.5 mole % Sr and 10 mole % rare-earth element to grade-A barium powder results in the substitution of barium ions by Sr and rare-earth ions; consequently, the energy of magnetic anisotropy changes and the technically important parameters B_r and (BH)_max increase.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 34–39, January, 1989.     

The spectrum of Nd in rare earth orthoaluminates. The trigonal to orthorhombic transition study of the level

Some structural and spectroscopic features of rare earth orthoaluminates are examined.The trigonal→ orthorhombic transition is studied in a series of Nd_xSm_1−xAlO₃ compounds. The evolution of the crystal structure is followed by X-ray analysis and optical absorption. The free ion and crystal field parameters of Nd³⁺ (4f³ configuration) are determined in LuAlO₃:Nd³⁺.The anomaly of the calculated splitting of the levels is slight, but well characterized in NdAlO₃. The spin correlated crystal field and orbitally correlated crystal field models are tested as well as an empirical correction which was proposed earlier.     

The effect of oxygen ordering through controlled exposure to oxygen on the superconductive properties of LaBa2Cu3Oy

In an effort to clarify the role of controlled oxygen exposure in the synthesis of LaBa₂Cu₃O_y samples which achieve zero resistivity above 90 K, we have prepared samples of La(_1+x)Ba(_2–x)Cu₃O_y with x approximately equal to 0 and with y varying between 6.22 and 7.00. We find that for large values of y, 6.88相似文献   

Structural relaxation time for various liquids

The structural relaxation time for series of various liquids (alkanes, aliphatic alcohols, and diols) are calculated from published data on the shear viscosity and the heat of evaporation per unit volume. Liquids having a 3D H-bond network (diols) are characterized by relaxation times one to two orders of magnitudes longer than those typical of liquids without such a network (alkanes and aliphatic alcohols).     

The influence of Na<Superscript>+</Superscript> on the anilinepropylsilica xerogel synthesis by using the fluoride nucleophilic catalyst

Anilinepropylsilica xerogel was obtained by using an appropriate organosilane and tetraethyl orthosilicate as precursor reagents. The gelation was carried out using HF and NaF as catalysts. The presence of Na⁺ (when NaF was used) resulted in a decrease in the final organic content of the materials. This effect was interpreted as an inhibition of the organosilane polycondensation possibly due to the Na⁺ interaction with the SiO^- groups of the hydrolyzed organosilane. The presence of Na⁺ also results in morphological changes in the xerogels.     

On the Physical Origin of Long-Ranged Fluctuations in Fluids in Thermal Nonequilibrium States

Thermodynamic fluctuations in systems that are in nonequilibrium steady states are always spatially long ranged, in contrast to fluctuations in thermodynamic equilibrium. In the present paper we consider a fluid subjected to a stationary temperature gradient. Two different physical mechanisms have been identified by which the temperature gradient causes long-ranged fluctuations. One cause is the presence of couplings between fluctuating fields. Secondly, spatial variation of the strength of random forces, resulting from the local version of the fluctuation-dissipation theorem, has also been shown to generate long-ranged fluctuations. We evaluate the contributions to the long-ranged temperature fluctuations due to both mechanisms. While the inhomogeneously correlated Langevin noise does lead to long-ranged fluctuations, in practice, they turn out to be negligible as compared to nonequilibrium temperature fluctuations resulting from the coupling between temperature and velocity fluctuations.