Matrix mediated alignment of single wall carbon nanotubes in polymer composite films

Alignment of single wall carbon nanotubes (SWNT) in liquid crystalline (LC) polymer matrix imparting orientation to the nanotubes along the nematic director was studied by atomic force microscopy, measurements of electrical conductivity and Raman spectroscopy of the composite in the directions parallel and perpendicular to the nematic director. The composites were prepared through dispersion of SWNT with LC monomer in a common solvent, their alignment in nematic monomer and consequent UV polymerization of the monomer. The anisotropy of electrical and optical properties of the system depends strongly on the concentration of the nanotubes in the range of 1-10% SWNT being especially strong for smaller concentrations and negligible at higher loads. A simple semi-quantitative model is suggested to account for the orientational behavior of nanotubes in nematic matrices. It successfully describes the observed anisotropy of physical properties at microscale (up to 200 μm) in terms of anchoring of the polymer chains to the nanotubes surface and adjustment of the nanotubes orientation to the nematic direction due to such coupling. The increasing disorientation of the nematic domains at higher nanotubes loads is explained as a development of larger number of LC defects induced by the nanotubes in the nematic matrix due to their intrinsic nature of aggregation. The anisotropy of physical properties at macro scale (several millimeters) is much smaller and less dependable on SWNT concentration because differently oriented LC domains effectively wash out the anisotropy.     

Upgrading of a reliable water supply system at the Kola nuclear power plant for service life extension

Measures taken to develop and put into operation three new exterior channels for emergency process water with two additional 60VTs pumping units, which remain operational even during an earthquake and were installed in the second block pumping station, are described. In addition, the three existing 12NDS horizontal pumping units were used as a basis to develop a third channel for the emergency process water. Above-ground water ducts with thermal insulation and heating systems to prevent freezing during the anticipation state, which is the constant state of the emergency system, were laid. As a result of upgrading with the development of three channels, the emergency process water feeding reached an adequately safe level of reliability. __________ Translated from Atomnaya énergiya, Vol. 100, No. 3, pp. 173–177, March, 2006.     

Design of computational processes in hierarchic systems

A suboptimal algorithm of scheduling in hierarchic systems is considered. The algorithm does not practically require the enumeration of possibilities. The results on the efficiency of this algorithm are given based on the random generation of examples.     

Temperature Dependence of the Magnetic Properties of Amorphous Fe-Me-Si-B Alloys

Alloying of amorphous Fe-Me-Si-B metallic compositions with nickel and molybdenum results in a decrease in the values of saturation magnetization in fields with a magnetic intensity of 0.72 MA/m. The same alloying additions decrease the temperature of formation of new magnetic Fe₃B-type phases, which are stable up to 873 ± 5 K.     

Nonequilibrium nonstoichiometry in ionic compounds

Ionic substances under normal conditions are stoichiometric compounds with phase diagrams featuring no homogeneity regions. Crystals grown under nonequilibrium conditions, in particular, under significant centrifugal acceleration, are characterized by nonstoichiometric compositions (e.g., K_2−x Br_1.07). In this way, it is possible to obtain nonequilibrium nonstoichiometric ionic compounds possessing certain homogeneity regions. Nonstoichiometric crystals of KCl, KBr, and KI grown under various accelerations ranging within (1.3–100.0)×10³ g exhibit insignificant variations in the lattice constants and a significant increase in micro-hardness with acceleration.     

Exergy losses in refrigerating systems. A study for performance comparisons in compressor and condenser

A study is carried out to describe irreversibilities in one stage refrigerating process for vapour compression cycle with refrigerant mixtures R-404A, R-410A, R-410B and R-507 as working fluids. They are calculated as exergy losses by an algorithm developed on the basis of thermodynamics. The proposed relationships have been derived from exergy balances on the system components. Emphasis is placed on parameters influencing the losses and the related results are presented through Grassmann diagrams (diagrams of exergy fluxes). Furthermore, detailed information on the variation of cycle's exergy efficiency with evaporating and condensing temperatures is given. Copyright © 2003 John Wiley & Sons, Ltd.     

Reliability Analysis of the Systems with Many States on the Basis of the Algebra of Tuples

A new approach to the modeling and analysis of systems with many states is set out, which makes it possible to perform calculations of probability characteristics of these systems. This approach relies on the algebra of tuples, with the aid of which a system with many states is represented in the form of an aggregate of multiple relations, so that the system proves to be isomorphic to the algebra of sets.     

Fuel‐Consumption‐Minimum‐Based Selection of the Regime of Heating of a Metal by the Main Optimization Method

Consideration is given to the solution of the problem of minimization of fuel consumption in heating a rectangular prism in a continuous furnace.     

Investigation of physical processes in the centrifugal dispersion of materials with high vapor and gas release

We have analyzed the physical processes in a vacuum chamber in the centrifugal dispersion of blanks of D16 and AMg6 aluminum blanks rotating at a rate of 10–80 m/sec with local melting under the action of a stationary electron beam of power density ∼10⁹ W/ m². A method for approximate calculations of melting under flash heating, diffusion, and vapor and gas release into vacuum is proposed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 2, pp. 25–35, March–April, 2007.