On the calculus of positively constructed formulas for automated theorem proving

The paper deals with an expressive logic language LF and its calculus. Formulas of this language consist of some large-scale structural elements, such as type quantifiers. The language LF contains only two logic symbols—∀ and ∃, which form the set of logic connectives of the language. The logic calculus JF and complete strategy for automated proof search based on a single unary rule of inference are considered. This calculus has a number of other features which lead to the reduction of the combinatorial complexity of finding the deductions in comparison to the known systems for automated theorem proving as the Resolution method and Genzen calculus. Problems of effective implementation of JF as a program system for automated theorem proving are considered.     

Graphene/Half-Metallic Heusler Alloy: A Novel Heterostructure toward High-Performance Graphene Spintronic Devices

Graphene-based vertical spin valves (SVs) are expected to offer a large magnetoresistance effect without impairing the electrical conductivity, which can pave the way for the next generation of high-speed and low-power-consumption storage and memory technologies. However, the graphene-based vertical SV has failed to prove its competence due to the lack of a graphene/ferromagnet heterostructure, which can provide highly efficient spin transport. Herein, the synthesis and spin-dependent electronic properties of a novel heterostructure consisting of single-layer graphene (SLG) and a half-metallic Co₂Fe(Ge_0.5Ga_0.5) (CFGG) Heusler alloy ferromagnet are reported. The growth of high-quality SLG with complete coverage by ultrahigh-vacuum chemical vapor deposition on a magnetron-sputtered single-crystalline CFGG thin film is demonstrated. The quasi-free-standing nature of SLG and robust magnetism of CFGG at the SLG/CFGG interface are revealed through depth-resolved X-ray magnetic circular dichroism spectroscopy. Density functional theory (DFT) calculation results indicate that the inherent electronic properties of SLG and CFGG such as the linear Dirac band and half-metallic band structure are preserved in the vicinity of the interface. These exciting findings suggest that the SLG/CFGG heterostructure possesses distinctive advantages over other reported graphene/ferromagnet heterostructures, for realizing effective transport of highly spin-polarized electrons in graphene-based vertical SV and other advanced spintronic devices.     

Study of radiolysis products in tracks over the distance from the ion trajectory in polyethylene terephthalate and polycarbonate

Latent tracks and track-etched membranes micro- and nanosized entities are promising research objects. The peculiarity of such structures is that they are discrete in nature. As the distance from the track axis increases, the physical and chemical characteristics of these entities change to their original values. The track size also depends on the mass and energy of energetic ions. For example, the maximum size of Kr ions with an energy of 1 to 2 MeV/amu is 50 nm according to preliminary data. Changes in the track area over the distance from the ion trajectory have been studied in this work.     

Measurements of linear dimensions of silicon nanorelief elements with a near-rectangular profile by defocusing the electron probe of a scanning electron microscope

Solitary silicon nanorelief elements with different widths are studied with the use of a scanning electron microscope (SEM). From the video signal curves obtained in the secondary-slow-electron mode of SEM measurements, the dependences of the length of check segments G _p (D _ef) and L _p (D _ef), where D _ef is the effective diameters of the SEM probe, are determined. The dependences are found to be linear for all four solitary protrusions, and as D _ef is increased, the length G _p increases and the length L _p decreases. It is shown that the method of defocusing the SEM electron probe provides a means for determining the linear dimension of nanorelief elements with a near-rectangular profile by extrapolating the linear dependences G _p (D _ef) and L _p (D _ef) to D _ef = 0. It is established that the invariant check segment representative of the linear dimension of a particular relief element is at the level (sl)_aver = 0.80 ± 0.03 for silicon elements with different widths.     

A gas compressor based on a piston-type acoustic resonator

Major differences are pointed out between the design and working principles of a piston acoustic gas compressor and piston-based pumps and compressors. Working forms are given for the amplitude of the gas speed oscillation in the tube and the compressor throughput. The throughput is calculated for a tube of length 3.5 m with internal diameter 0.04 m and piston stroke length of 0.004 m. It exceeds that of a normal piston compressor with the same energy consumption by a factor of 8.     

Reactions of V<Subscript>2</Subscript>O<Subscript>5</Subscript>, Nb<Subscript>2</Subscript>O<Subscript>5</Subscript>, and Ta<Subscript>2</Subscript>O<Subscript>5</Subscript> with AlN

Reactions of vanadium, niobium, and tantalum pentoxides with aluminum nitride have been studied using X-ray diffraction. At temperatures from 1000 to 1600°C, we have identified various V, Nb, and Ta nitrides. The composition of the niobium and tantalum nitrides depends on the reaction temperature. The tendency toward nitride formation becomes stronger in the order V₂O₅ < Ta₂O₅ < Nb₂O₅.     

Basic Technological Features of Production and Performance Evaluation of Proppants Used in Oil and Gas Production by Hydraulic Fracturing

Glass and Ceramics - The results of studies of the structure, phase composition, and mechanical and chemical properties of aluminosilicate, magnesia-quartz, and glass-ceramic proppants (RosProp,...     

A radiographic facility for the 70-GeV proton accelerator of the institute for high energy physics

A radiographic facility for the 70-GeV proton a ccelerator of the Institute for High Energy Physics is described. The available infrastructure in the initial straight part of the injection channel is used in the facility. The 100-mm-diameter lenses of the injection line ar e intended for transportation of the proton beam from the U-70 accelerator to the accelerating—storage complex. The facility has been designed only for an energy of 50 GeVwith a viewfield of 60 mm and used for imaging of samples with an optical density of >300 g/cm² in the presence of some losses in the line. The optical resolution of the facility is 0.25 mm. A set of experiments aimed at multiframe recording of fast processes were conducted on the facility in 2004-2008. Small-sized explosion-proof chambers, as well as the measuring system for monitoring the state of the chamber and environment, were used in the dynamic experiments.