Russian underwater tunnels in the system of international transportation ways

Sustained world economic development trends characteristic with international trade annual growth rate of 7–8% along with considerable dynamics in the interregional goods circulation sphere on one hand and vast territory of Russia combined with a relatively developed railway network on the other hand provide a unique chance for this country to arrange land transportation routes alternative and competitive in comparison with existing marine routes. Construction of rail tunnels seems to be most efficient means for transportation corridors to cross-wide water areas like Nevelsky Strait (10.5 km) between the mainland and the Sakhalin Island in Russia, Bering Strait (92 km) between Chukotka Peninsula (Russia) and Alaska (USA). The tunnels construction conditions, structures and technologies planned to be used are considered in the paper.     

Microstructures formed by spray freezing of food fats

The spray-freezing of two food fats, tripalmitin (PPP) and cocoa butter (CB) and mixtures thereof, has been modeled experimentally using a novel single droplet freezing apparatus configured so that temperature profiles or samples for microstructure analysis can be obtained. For 2 mm diameter droplets suspended in a cold air flow at temperatures around 2–15°C, initial cooling rates were on the order of 10 K s⁻¹ and the temperature profiles could be correlated directly to DSC data collected at 20 K min⁻¹, indicating that minimal supercooling of the materials occurred in the droplet form. Microstructure analysis confirmed that PPP crystallized preferentially in mixtures, and that the surface structure was very sensitive to storage conditions. The bulk structure was much less sensitive, and the internal microstructure of the PPP droplets revealed distinct nucleation sites, which were absent from the CB: These persisted in the mixtures up to 50 wt%. X-ray analysis indicated that the fats crystallized in their more stable forms, namely, β for PPP and Form V/V1 in CB.     

Quantum Dots-Based Optical Fiber Temperature Sensors Fabricated by Layer-by-Layer

Two types of CdTe quantum dots of different sizes (4 and 5 nm) were successfully deposited on optical fibers using the layer-by-layer electrostatic self-assembly method. The sensors showed a linear and reversible variation of the emission wavelength for a temperature range from 30 degC to 100 degC, with a sensitivity of 0.2 nm/degC     

Contributions of the interior and surface states of charge carriers to the emission spectra of CdS quantum dots in borosilicate glasses

The photoluminescence spectra of CdS quantum dots grown in a borosilicate glass by sol-gel technology are recorded and analyzed. It is shown that the photoluminescence spectra of the samples are related to annihilation of free (interior) excitons in the ground state and excited state. Emission associated with the surface states of the quantum dots is detected in the region around 2.7 eV for the first time. The emission is due to recombination of electrons localized at the surface with heavy holes in the free states of the quantum dots. Resonance excitation of the structures makes it possible to reveal the specific features of the localized surface states responsible for the photoluminescence band. The properties of the band are, to a large extent, similar to the properties of the emission bands of both three-dimensional media (amorphous semiconductors and substitution alloys) and two-dimensional systems (quantum wells and superlattices).     

Electrical characteristics of the ITO/HgInTe photodiodes

Photodiodes designed to be sensitive in the region 0.5–1.7 μm and obtained by vacuum magnetron sputtering of the ITO (SnO₂ + In₂O₃) layer on the surface of the Hg₃In₂Te₆ single crystal are studied. The electrical characteristics, measured at 265–333 K, indicate that the mechanism of charge transport in the diodes under study is thermionic. The current-voltage characteristic and its temperature variations are described quantitatively based on the energy diagram and the found parameters of the heterojunction. Original Russian Text ? L.A. Kosyachenko, I.M. Rarenko, E.F. Sklyarchuk, I.I. German, Sun Weiguo, 2006, published in Fizika i Tekhnika Poluprovodnikov, 2006, Vol. 40, No. 5, pp. 568–571.     

Measurement of target coordinates in three-dimensional bistatic forward-scattering radar

The maximum-likelihood technique is applied to determine the coordinates of moving targets in a three-dimensional bistatic forward-scattering radar. The potential accuracy of the coordinates’ determination is estimated. Simulation results are presented.     

Thomson scattering diagnostic systems in the ITER divertor

A diagnostic array has been developed for studying the operating modes of the divertor in the ITER tokamak-reactor using the Thomson scattering technique. The aim of this study is to measure the spatial profiles of the electron temperature and density. The structure of the diagnostic setup was selected on the basis of a classical diagnostic geometry and the high-resolution LIDAR system, which provide access to different regions of the divertor plasma. A severe radiation environment, limited access to the plasma in the ITER divertor, and a high-dust environment (the divertor plate erosion material) in the divertor volume pose many problems for performing diagnostics under unique conditions having no analogs in the tokamaks that are now in operation. Different methods for protecting optical surfaces from plasma-enriched deposition are proposed and analyzed. The efficiency of these methods has been demonstrated in bench tests. The concept of laser and detector systems and diffraction polychromators capable of operating at different electron temperatures with a lower limit of 1 eV, has been justified and approved.     

An efficient electron-beam-pumped semiconductor laser for the green spectral range based on II–VI multilayer nanostructures

Emission characteristics of an electron-beam-pumped Cd(Zn)Se/ZnMgSSe semiconductor laser are studied. The laser’s active region consists of a set of ten equidistant ZnSe quantum wells containing fractional-monolayer CdSe quantum-dot inserts and a waveguide formed by a short-period superlattice with the net thickness of ～0.65 μm. Lasing occurs at room temperature at a wavelength of 542 nm. Pulsed power as high as 12 W per cavity face and an unprecedentedly high efficiency of ～8.5% are attained for the electron-beam energy of 23 keV.     

Total classes of composition systems of discrete signals in isomorphous Galois fields

It is proposed a rule of total classes of composition systems of discrete frequency signals (CDF-signals) construction in extended Galois fields. It is carried out modeling and research a correlation properties of CDF-signals, and determined their practical attraction.