Strategic Risk of Drones

Russian Engineering Research - The feasibility of pilotless aerial vehicles (drones) is considered. Their properties are identified and compared with those of piloted vehicles. The strategic risk...     

Assessing the Strategic Efficiency of Aviation Projects

Russian Engineering Research - The strategic efficiency of a project is defined. An approach to assessing the strategic efficiency of projects is outlined. This approach, incorporated in the State...     

Determination of the level of seismic danger and design seismic loads for large hydrotechnical structures

A local network of sensitive high-accuracy seismological stations has to be created for seismological observations near a hydrotechnical structure and on the banks of the storage reservoir. The layout of the network is chosen with allowance for the configuration of the reservoir and for the location of the seismogenerating zone relative to the structure. __________ Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 11, November 2005, pp. 16–26.     

High-Pressure Phase Transition of Hexagonal Alkali Pnictides

High-pressure studies of Li₃P, Na₃Sb, and Na₃Bi at room temperature show that these compounds undergo a reversible transition from a hexagonal phase to a denser, cubic phase. The lattice parameters of the cubic phases are determined at pressures of up to 9.0 GPa.     

New Cubic Phases in the Li–Na–Sb–Bi System

New compounds with the general formula A _x A"_3-x B _y B"_1-y (A, A" = Li, Na; B, B" = Sb, Bi) were prepared in the system Li–Na–Sb–Bi. Na₃Sb_0.5Bi_0.5has a hexagonal structure (Na₃As type, a= 5.415 Å, c= 9.595 Å), and Li₃Sb_0.5Bi_0.5and Li₂NaSb_0.5Bi_0.5have a cubic structure (BiF₃type, a= 6.645 and 6.772 Å, respectively). The phase transitions of alkali-metal pnictides were studied by in situ x-ray diffraction at room temperature and pressures from 10⁵Pa to 9.0 GPa. Li₃Sb and Na₃Sb were each shown to exist in two polymorphs with hexagonal (Na₃As type) and cubic (BiF₃type) structures. At atmospheric pressure, Li₃Sb undergoes an irreversible – phase transition at 650°C, while Na₃Sb undergoes a reversible transformation into a cubic phase at 2.3 GPa and room temperature.     

The effect of the nature and structure of organic components of copper-plating sulfate bath on the electroplating kinetics,structure, and physicomechanical properties of coatings

The rate and kinetics of electrochemical reduction of Cu²⁺ ions in aqueous and aqueous methylpyrrolidone electrolytes are found to depend on the structure of organic additives, which were derivatives of N-(2′-hydroxybenzyl)aniline with electron-donating or electron-withdrawing substituents. An increase in the content of cyclic lactam in the electrolyte is shown to result in the efficiency of all the additives studied, especially Cl-substituted compound. Electron microscopic studies revealed the substantial improvement of the microstructure of deposits obtained from aqueous methylpyrrolidone electrolytes containing aniline derivatives. Tribological and elastic characteristics of the coatings are improved, and microhardness increases in certain cases.     

On some alkali- and alkaline-earth-metal boron nitrides, unsaturated with boron

Three new lithium, magnesium and calcium boron nitrides, namely Ca₆BN₅(L), Mg₆BN₅(H) and Li₃Mg₃B₂N₅(L), were synthesized using a metal nitride–boron nitride sintering technique at low (L) or high (H) pressures. All these new compounds are typical metal boron nitride powders and, like previously known Mg₃BN₃, seem to have the N³⁻ anion in their structures.     

Use of a program package for comparison of radiographic images of tissues during treatment

Repeated courses of laser therapy given to patients with ischemic heart disease, angina of effort class I-IV for 2 years brought about stabilization of coronary insufficiency and improvement of clinical and functional conditions. Microcirculatory picture of the bulbar conjunctiva, coronary reserve improved. The treatment had also a hypotensive effect.