Variability of coronal structures and ion components in the solar wind

The variations of solar wind ion fluxes of protons and-particles are studied in a wide timescale: from parts of a second to several months. A persistence time of about 60 hours was obtained for the large-scale variations of-particles. Power density spectra of velocity, density and magnetic field were studied in the frequency range from 10^–5 to 10^–3 Hz. Middle-scale fluctuations of both protons and-particles are close to each other and the spectrum for-particles has a somewhat greater slope than that for protons. Estimates of the variations of the flux power density are given in the frequency range from 10^–3 to 3 Hz.Presented at the VII STP-Symposium in the Hague (Netherlands), 1990.     

Phonons in Ge/Si quantum dot structures: influence of growth temperature

In this paper we present the results of a Raman study of Ge/Si quantum dot (QD) superlattices grown with different thicknesses of a Si interlayer and at different substrate temperatures. The built-in strain and atomic intermixing in the QDs are deduced from an analysis of optical phonon frequencies of the QDs obtained from Raman spectra of the structures.     

Rate determining factors in protein model structures

Previous research has shown a strong correlation of protein folding rates to the native state geometry, yet a complete explanation for this dependence is still lacking. Here we study the rate-geometry relationship with a simple statistical physics model, and focus on two classes of model geometries, representing ideal parallel and antiparallel structures. We find that the logarithm of the rate shows an almost perfect linear correlation with the "absolute contact order", but the slope depends on the particular class considered. We discuss these findings in the light of experimental results.     

The influence of transverse structures on the coupling of solid-state lasers

We demonstrate the influence of transverse structures on the coherent coupling of laser modes. From the Maxwell-Bloch equations in the approximation of a finite mode expansion we derive Adler equations for the relative phases. We use an improved model to describe the gain-induced coupling of two non-orthogonal modes of a solid-state laser. Experimental results for some time-dependent experiments are presented and compared with theoretical predictions of our model.     

Using the photopyrometric method for determining temperature fields

A photopyrometric method is described with special emphasis on its practical application. The accuracy of the method is evaluated, the temperature range in which it can be used is determined and, the conditions of its use in gas studies are considered.     

The role of demagnetization factor in determining the ‘true’ value of the Curie temperature

The Curie temperature, T_C, is the temperature above which a material loses its long-range ferromagnetic order. Considering the equation of state of a ferromagnet in the mean-field approximation it has been shown theoretically that the value of the demagnetization factor N has a significant influence on the perceived location of T_C on the temperature scale. A series of precise measurements of magnetization using two differently shaped single crystals of high-purity gadolinium was carried out to prove this result experimentally and develop a procedure leading to the ‘true’ value of T_C.     

Large two-dimensional clusters of equal-area bubbles: The influence of the boundary in determining the minimum-energy configuration

Finite monodisperse two-dimensional clusters of bubbles are shown to behave like a crystal rather than a liquid. They attain their lowest-energy configuration when they find an arrangement close to a hexagonal lattice, as predicted by the Wulff construction. The deviation from hexagonal shape of the bubbles in a cluster and the variation in bubble pressure throughout the structure are calculated. It is shown that the effect of reducing the length of the boundary is negligible, explaining why configurations retaining the structure of the lattice will give the lowest energy.     

The influence of electric-field penetration upon electron distribution in M-I-M structures

The penetration of the electric field into the electrodes can modify the angular distribution of electrons in the basic metal electrode of the sandwich cathode. Electrons obtain additional energy n the normal direction so that the transmission probability of the dielectric potential barrier ncreases. The change of the leakage current can reach the value of tens per cent.     

The influence of temperature on the optical properties of gold nanoparticles

The optical properties of gold nanoparticles in a transparent matrix are studied at temperatures from 300 to 1000 K within the spectral range from 450 nm to 1.5 μm. It is shown that, in the case of small nanoparticles and short wavelengths in the plasmon resonance band, an increase in temperature leads to a decrease in the absorption efficiency factor. The light absorption efficiency factor of gold nanoparticles with a radius exceeding 40 nm increases with increasing temperature in the entire spectral range studied. The single scattering efficiency factor always decreases with increasing temperature. The effects observed are related to a change in the refractive indices of gold and the matrix with comparable contributions. It is shown that results of calculations agree qualitatively with available experimental data. The results are necessary to optimize the composition of the actuators, including gold nanoparticles, in the transparent matrices.     

The influence of finite cavities on the sound insulation of double-plate structures

Lightweight walls are often designed as frameworks of studs with plates on each side--a double-plate structure. The studs constitute boundaries for the cavities, thereby both affecting the sound transmission directly by short-circuiting the plates, and indirectly by disturbing the sound field between the plates. The paper presents a deterministic prediction model for airborne sound insulation including both effects of the studs. A spatial transform technique is used, taking advantage of the periodicity. The acoustic field inside the cavities is expanded by means of cosine-series. The transmission coefficient (angle-dependent and diffuse) and transmission loss are studied. Numerical examples are presented and comparisons with measurement are performed. The result indicates that a reasonably good agreement between theory and measurement can be achieved.     

The influence of breaking of exchange bonds on the Curie temperature

The size effect of magnetically ordered nanoparticles on the Curie temperature is discussed. For a system of Fe₃O₄ nanoparticles with different dispersities, it is demonstrated that the smaller the size of the particles, the larger the thickness of their surface layer, which is characterized by considerable distortions of the regular structure.     

Theoretical split-window algorithms for determining the actual surface temperature

Summary Two split-window strategies for obtaining the actual surface temperature (AST) from an infra-red sensor system are investigated by means of simulations of radiometer signals for a wide range of different geophysical situations. The differences between strategies are closely related to the strong or weak presence of atmospheric effects in the split-window coefficient. It has been demonstrated that the strong presence makes it necessary to know the total atmospheric water vapour as well as the effective emissivities in the two thermal channels for applying the strong split-window method, whereas for the weak presence one only needs to know the emissivities. Simplified algorithms have been obtained from these methods when some of the input data are unknown. Likewise, included for all these algorithms is a rigorous evaluation of their accuracies that takes into account the uncertainties in the emissivity and the noise-equivalent temperature. In this way several algorithms are provided for determining the AST, leaving to the choice of the reader the algorithm that best responds to the required accuracy and the available input data.     

The influence of temperature on superplasticity of Zn-Al-Cd alloy

Experimental results of the study of superplastic behaviour in Zn-0·35 wt. % Al-0·25 wt. % Cd alloy are presented. The attention has been paid to the influence of temperature on stress-strain curves, ductility, strain rate sensitivy parameterm and activation energy of superplastic flow. The best superplastic properties have been established at temperatures T370 K (0·53 T_m): ductilityA=600% and parameterm=0·56. A fast grain growth observed at temperaturesT 380 K has been suggested to be responsible both for the decrease in ductility and parameterm values and for the origin of an anomaly in the decreasing temperature dependence of flow stress. The measurements of activation energy have shown an expected decrease in activation energy at the transition from the non-superplastic region at lower temperatures to the superplastic region at higher temperatures. Significant transient effects after strain rate changes have been observed. The experimental results obtained in the Zn-Al-Cd alloy have been compared with those obtained in binary Zn-1·1 wt. % Al alloy and discussed from the point of view of possible models of structural superplasticity.     

The influence of temperature fields on the orientational relaxation in hybrid liquid-crystal cells

The relaxation of the director field $ \hat n The relaxation of the director field , the velocity field v, and the shear and normal components of the stress tensor in a hybrid liquid-crystal cell with differently heated bounding surfaces is investigated theoretically. The system of nonlinear hydrodynamic equations that describe the director reorientation with allowance made for the field of velocities v induced by the director reorientation, on the one hand, and by the temperature gradient, on the other hand, is solved numerically. The relaxation time and the influence of the velocity field on the relaxation processes are analyzed for a number of hydrodynamic regimes arising in the hybrid liquid-crystal cell under the effect of the temperature field. Original Russian Text ? A.V. Zakharov, A.A. Vakulenko, 2008, published in Fizika Tverdogo Tela, 2008, Vol. 50, No. 3, pp. 557–564.     

The influence of ionic temperature on plasmasphere structure formation

The formation of the three-dimensional structure of the plasmasphere-ionosphere system under the action of ionization/recombination, charge exchange, and field-aligned (along geomagnetic field lines) diffusion of the O⁺ and H⁺ ions was studied by numerical simulation with the use of the global theoretical model of the upper atmosphere of the Earth (UAM). These processes were shown to form a spatially inhomogeneous and nonstationary plasma sheath of the Earth with several large-scale structural total plasma density and ionic composition singularities. A substantial contribution to their formation was made not only by the magnetic field geometry but also by ionic temperature spatial nonuniformity mainly determined by nonlocal heating with photoelectrons. The mechanism of this influence was studied.