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In the mountains of the moist-subtropical zone of Western Transcaucasia seven zones of snowiness are distinguished, depending on the heights from sea level to the tops of mountain ranges. Data are taken from 17 years of snow-avalanche observations. In a legend of a map the quantitative characteristic of the avalanching conditions for each zone is given. Interannual variability of snow depth is up to 100 cm in low mountains and about 600 cm in the middle belt of mountains The inversion of snow accumulation is registered. The frequency cycles of heavy-snow (3–4 years) and of especially heavy-snow (10–12 years) winters are determined. The avalanche danger is provoked not by the total depth of the snow, but by the stormy snowfalls. The particular conditions of creation and development of nival processes are distinguished here: dry avalanches on the crests of mountains, wet avalanches in the middle mountains and slushflows in the low mountains. Despite low avalanche activity, avalanche risk is high due to the factor of unexpectedness.
We present the analysis of BV photometry of BY Cam based on observations carried out in Crimea. The long QPOs in brightness were detected in both high and low brightness states. Their typical periods, equal to 6, 12 and 24 m, are found. The amplitude of the QPOs depends on the phase of Pbeat.
We consider the motion of a spherically-symmetric balloon satellite perturbed by the Earth’s oblateness and solar radiation pressure. For equatorial satellite orbits and neglecting the Earth obliquity, the orbit-averaged equations for eccentricity and longitude of pericenter are integrable in quadratures (Krivov and Getino, 1996). The instability zone associated with the saddle separatrix in the phase space has been found and explored in depth. For semimajor axes about two Earth’s radii, and for area-to-mass ratios in the order of several tens cm2g−1, the amplitude and period of eccentricity oscillations may change nearly twofold under a small change of initial conditions or force parameters. We then restore the actual Earth obliquity of 235 and consider a spatial (non-integrable) problem. Near the saddle separatrix, a stochasticity zone appears that leads to large unpredictable eccentricity variations. The quasirandom motions of space balloons are investigated in terms of two-symbol (0-1) sequences by methods of stochastic celestial mechanics.
This article aims to explore the microfoundations of political support under a nondemocratic regime by investigating the impact of a natural disaster on attitudes toward the government. The research exploits the enormous wildfires that occurred in rural Russia during the summer of 2010 as a natural experiment. The authors test the effects of fires with a survey of almost eight hundred respondents in seventy randomly selected villages. The study finds that in the burned villages there is higher support for the government at all levels. Most counterintuitively, the rise of support for authorities cannot be fully explained by the generous governmental aid. The authors interpret the results by the demonstration effect of the government's performance.
In various biological systems and small scale technological applications particles
transiently bind to a cylindrical surface. Upon unbinding the particles diffuse in the
vicinal bulk before rebinding to the surface. Such bulk-mediated excursions give rise to
an effective surface translation, for which we here derive and discuss the dynamic
equations, including additional surface diffusion. We discuss the time evolution of the
number of surface-bound particles, the effective surface mean squared displacement, and
the surface propagator. In particular, we observe sub- and superdiffusive regimes. A
plateau of the surface mean-squared displacement reflects a stalling of the surface
diffusion at longer times. Finally, the corresponding first passage problem for the
cylindrical geometry is analysed.
Results of finite element analysis of linked two and three scale levels tasks are presented. Fields of components of stress concentration tensor function for several models of unit cells of textile composite materials are presented too. Comparison of experimental and computational results of obtained effective properties was carried out and results of this research are introduced. The basis of this phenomenological approaches was made by Prof. N.S. Bahvalov and Prof. B.E. Pobedriya in 80's and finally this method was renovated by Prof. Yu.I. Dimitrienko at Bauman Moscow State Technical University at «Computational mathematics and mathematical physics» department. Computational procedures and program implementation was made using object-oriented design and C/C++ language by A.P. Sokolov. All computational results have been performed using new-developed distributed high-perfomance software system GCD. Multiscale homogenization method was applied for single macroscopic level of composite construction and several connected microscopic levels. The task of stress-strain determination of composite construction was stated automatically by means of automatically defined plan based on certain computational problems. Architecture of software system and finite-element subsystem were developed too. Several practically important tasks were solved and some of its results are attached.
The UBVRI photometric follow-up of SN 2011fu has been initiated a few days after the explosion, shows a rise followed by steep decay in all bands and shares properties very similar to that seen in case of SN 1993J, with a possible detection of the adiabatic cooling phase at very early epochs. The spectral modeling performed with SYNOW suggests that the early-phase line velocities for H and Fe ii features were ~ 16000 km s−1 and ~ 14000 km s−1, respectively. Studies of rare class of type IIb SNe are important to understand the evolution of the possible progenitors of core-collapse SNe in more details.
If graphene is to be incorporated into transistors, solar cells, and capacitors, a large-scale synthesis of graphene must be devised. This research developed an innovative, simple, and cost-efficient synthesis procedure, dispersing graphene oxide in an ethanol-water solvent and reducing slowly with sodium borohydride (NaBH4). Reducing graphene oxide in 75:25 and 50:50 H2O:ethanol solutions with 15 mmolar NaBH4 produced numerous single-layered reduced graphene oxide sheets >1 μm2, and sometimes even >2 μm2. The quality of these sheets was confirmed by Raman spectroscopy, XRD, TGA, TEM, ED, and HRTEM.
The charge transport and quantum interference effects in low-dimensional mesoscopic carbon networks prepared using self-assembling were investigated.
The mechanism of conduction in low-dimensional carbon networks was found to depend on the annealing temperature of the nitrocellulose precursor. The charge transport mechanism for carbon networks obtained at Tann=750°C was found to be the hopping conductivity in the entire investigated temperature range. The Coulomb gap near the Fermi level in the density of states was observed in the investigated carbon networks. The width of the Coulomb gap was found to be decreased with the annealing temperature of the carbon structures. The crossover from the strong localization to the weak localization regime of the charge transport in the carbon structures, obtained at Tann=950°C and Tann=1150°C, was observed in the temperature range T>100 K and T>20 K, respectively.
The charge transport and quantum interference effects in low-dimensional mesoscopic carbon networks prepared using self-assembling were investigated. The mechanism of conduction in low-dimensional carbon networks was found to depend on the annealing temperature of the nitrocellulose precursor. The charge transport mechanism for carbon networks obtained at Tann=750 0C was found to be the hopping conductivity in the entire investigated temperature range. The Coulomb gap near the Fermi level in the density of states was observed in the investigated carbon networks. The width of the Coulomb gap was found to be decreased with the annealing temperature of the carbon structures. The crossover from the strong localization to the weak localization regime of the charge transport in the carbon structures, obtained at Tann=950 0C and Tann=1150 0C, was observed in the temperature range T>100 K and T>20 K, respectively.
The diffusion of aluminum in silicon carbide during high-temperature A1+ ion implantation was studied using secondary ion mass spectrometry (SIMS). Transmission electron microscopy (TEM) has been used to determine the microstructure of the implanted sample. A 6H-SiC wafer was implanted at a temperature of 1800 °C with 40 keV Al ions to a dose of 2 x 1016 cm-2. It was established that an Al step-like profile starts at the interface between the crystal region and the damaged layer. The radiation enhanced diffusion coefficient of Al at the interface was determined to be Di = 2.8 x 10-12 cm2/s, about two orders of magnitude higher than the thermally activated diffusion coefficient. The Si vacancy-rich near-surface layer formed by this implantation condition is believed to play a significant role in enhanced Al diffusion.
The process of formation of silicon nanoclusters in a silicate matrix by the focused electron beam of high power and their cathodoluminescent properties were studied in this paper. The size of the silicon clusters and their concentration depend on the electron beam power and on the properties of the silicate matrix (density, porosity, composition). In this paper we studied the evolution of cathodoluminescent properties in bulk silicon oxide, porous silicon oxide glass, silicagel (n·SiO2·m·H2O) and opal. The result of the modification of silica is the appearance of the CL bands at 2.3eV in green region, and the bands at 1.4 and 1.1eV. The CL intensity of these bands increases during the interaction with electron beam. The volt-ampere characteristics of the modified areas of the silica are non-linear and depend on the time of the interaction and the power of the electron beam. We relate the appearance of these new CL bands with formation of oxygen-deficit defects and silicon clusters.
Influence of internal mechanical stresses (IMS) and dislocations on conductivity mechanisms and reliability of light emitting diode (LED) and laser InAsPSb/InAs double heterostructures has been investigated. It was shown that the presence of lattice mismatch of layers at p-n-heteroboundaries changes LED conductivity mechanisms the same way as longterm working challenges by current. It was determined that LED degradation has barrier character and is followed by appearance and growth of tunnel current components with power dependence of current from voltage. Reliability and external quantum efficiency decrease with growth of lattice mismatch.
The diffusion of Al in 6H-SiC during high-temperature ion implantation was studied using secondary ion mass spectrometry. A 6H-SiC wafer was implanted with 50 keV Al ions to a dose of 1.4E16 cm−2 in the high temperature range 1300°–1800TC and at room temperature. There are two diffusion regions that can be identified in the Al profiles. At high Al concentrations the gettering related peak and profile broadening are observed. At low Al concentrations, the profiles have a sharp kink and deep penetrating diffusion tails. In the first region, the diffusion coefficient is temperature independent, while in the second it exponentially increases as a function of temperature. The Al redistribution can be explained with the substitutional-interstitial diffusion mechanism.
Epitaxial CdF2 layers, which may be used in light-emitting devices integrated with silicon, were grown by Molecular Beam Epitaxy (MBE). Characterization of the layers by Rutherford Backscattering Spectroscopy (RBS), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) showed that optimal growth temperature lies in the range 60–80°C. The sticking coefficient of CdF2 molecules was found to decrease at temperatures above 100°C. Different modes of misfit strain relaxation were observed above and below that temperature.
The evaluations of the following performances of detectors for design of the radiographic system were carried out by mathematical simulation method and experimentally: sensitivity to absorbed energy, noise level, form of apparatus function for spatial resolution of detectors array.
The results of calculations were used for designing of CdWO4-Si arrays with optimal sizes of scintillator and photodiode for resolution ability. At the given stage the quality of radiation detectors was evaluated by spectroscopic methods. At the bias voltage on photodiode 24 V, the sensitivity of detectors has made up (0,95–1,00) × 10−21 C / eV, noise level - (1,50–1,75) ×10−16 C together with electronic noise. Dynamic range at absorbed energy by separate detector is more than 105, what is sufficient to get required image contrast.
The aim of the study is to discuss the most general aspects of semiconductor devices durability and reliability. The life time of a semiconductor device is related to the defect structure evolution of the crystalline and noncrystalline components involved. The driving force for the evolution of defect device structure is associated with relaxation processes of internal mechanical stresses. In this report the degradational effects in LEDs based on GaAs(Si) have been analyzed. The discussion of the necessity for research on composite materials creation is also included.
To fabricate nanometer-sized Ge dots on Si(100), we have investigated multi-step procedure, involving low temperature deposition of a Ge layer, a sub-monolayer C on a Ge wetting layer, a Ge top layer for three-dimensional (3D) dot formation and post-annealing. Effects of each procedure were discussed on the basis of an atomic force microscope study. 10nm-sized Ge dots with a high number density in the order of 1011 cm−2 were grown on the Si(100) substrate by combining each procedure and optimizing experimental conditions, such as deposition temperature, the C layer thickness and post-annealing temperature.
We report on the results for the diffusion coefficient (D*) of polystyrene (PS) chains near the PS/Silicon interface. The present study employs secondary ion mass spectrometry (SIMS) to examine diffusion from a deuterated marker layer in thin PS films on silicon. The observed SIMS depth profiles are fit to numerical simulations of the diffusion process. The best fit is obtained for a super-linear dependence of D* vs. distance from the silicon wall. A non-trivial time dependence extending over tens of hours is observed for all the models tested.