Electrical and thermomechanical properties of materials based on nonstoichiometric titanium carbide prepared by self-propagating high-temperature synthesis

This paper examines the effect of the chemical and phase compositions of nonstoichiometric titanium carbide prepared by self-propagating high-temperature synthesis on the electrical and thermophysical properties of polymer compounds. Doping of titanium carbide with trace amounts of nitrogen raises the conductivity of the polymer compounds. The addition of epoxy to the polymer matrix markedly reduces the thermal expansion of the material. The proposed materials can be used at temperatures of up to 300–350°C.     

X-ray photoelectron study of the MoCl2C30H30 composite

The surface of a MoCl₂C₃₀H₃₀ composite in the form of molybdenum nanoclusters in a polyacetylene matrix, produced by reacting MoCl₅ with C₂H₂ in benzene and toluene, has been studied by X-ray photoelectron spectroscopy before and after Ar⁺ ion milling. The composite actively reacts with atmospheric oxygen and moisture. As a result, the molybdenum clusters on its surface oxidize to molybdenum(V) or molybdenum(VI) oxides or oxychlorides (E _b(Mo 3d _5/2) = 232.3–232.5 eV) during the sample preparation process. The electron binding energy of molybdenum affter surface etching (E _b(Mo 3d _5/2) = 228.5 eV) suggests that the oxidation state of the molybdenum in the composite is 2⁺ or 3⁺. Analysis of the structure of the spectrum of the C 2s electrons of the inner valence molecular orbitals using the energy level diagram of the C₂ molecule suggests that the hydrocarbon matrix of the composite contains, in addition to-CH=CH-CH=CH- conjugate bonds, linear carbyne fragments: -HC=C=CH- or -C≡C-. After etching, the surface layer of the composite contained argon, which might be due to adsorption because of the small particle size of the composite or chemisorption on the surface of the polyacetylene matrix. The composite is stable in a high vacuum of 1.3 × 10⁻⁵ Pa up to 350°C and does not experience charging when exposed to X-rays, which indicates that it has weak dielectric properties.     

Chaotic dynamics of oscillator based on lossless circuit

Equations that describe a new autooscillatory system with chaotic dynamics based on a lossless oscillatory circuit are presented. This system is capable of generating chaotic oscillations with irregular variations in the amplitude (amplitude chaos) at a small change in frequency. Bifurcation diagrams (one- and two-parametric), time series of the oscillatory process, and power spectra of the proposed system are presented.     

Secondary diffraction of diffracted Gaussian beam of laser radiation

The diffraction of a narrow Gaussian beam of laser radiation on mutually perpendicular edges of crossed, superimposed sharp wedge-shaped blades (safety razors) has been studied. The diffraction pattern observed on a flat screen behind the blades comprises a very bright central spot, which exhibits the structure of a “light network” with rectangular cells, and four groups of narrow bright bands that expand from the central spot toward the periphery and form a rectangular cross. The spatial frequency of light-field modulation on the screen can be controlled by varying the distance from the blades to screen.     

Formation of silicon nanocrystals in SiN<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript> film on PET substrates using femtosecond laser pulses

The formation of Si nanoclusters under the action of femtosecond laser pulses in a SiN _x film containing excess silicon has been studied. The initial film was grown by plasmachemical deposition at 100°C on a PET substrate. The pulsed crystallization was effected by a Ti-sapphire laser operating at a wavelength of 800 nm and a pulse duration of about 50 fs. According to the Raman spectroscopy data, the pulsed laser annealing stimulated the accumulation of excess silicon in nanoclusters and their crystallization. The proposed approach can be used for the formation of semiconductor nanocrystals in dielectric films on various plastic (polymer) substrates.     

Inhibitor protection of the steel reinforcement of armored concrete damaged by cracks

For corrosion-electrochemical investigations, we have developed and manufactured original model concrete specimens-cells to identify testing conditions for six reinforcement specimens. We have studied the polarization characteristics of model specimens held in an environment of weak-acid rain, as well as the kinetics and frequency dependences of impedance characteristics. It has been established that, for the rust protection of steel reinforcement, an inhibiting mixture containing equal quantities of sodium molybdate and calcium nitrate is the most efficient. Its inhibiting efficiency is 10 to 12 times as high as the efficiencies of its components separately, which demonstrates the synergetic effect. The mechanism of the synergetic protective action of these inhibitors lies in passing two processes, which mutually strengthen each other, on the metal surface. The addition of inhibitor to the polyurethane injection composition, applied for the repair of armored concrete structures, increases the strength of adherence of reinforcement with concrete, subjected to the long-term action of a corrosive environment, as compared with noninhibited. Using the synergetic effect in developing inorganic inhibiting mixtures, one can reduce significantly the consumption of materials and improve substantially the manufacturability of injection polymeric compositions for the repair of armored concrete structures of long-term operation.     

Approximation of the solution of inverse problem of scattering of electromagnetic waves on plane dielectrics

We propose a method for the determination of the material parameters of dielectric coatings according to the measured values of scattered electromagnetic fields which enables us to introduce an efficient procedure of processing of the data of measurements in the methods of nondestructive testing. As a specific feature of the proposed method for the solution of the formulated inverse problem, we can mention the possibility of reconstruction of piecewise continuous profiles of dielectric permittivity for laminated materials. The procedure of reconstruction is based on the method of integral equations. The solution of the problem is obtained approximately. The measured values of the coefficient of reflection of plane electromagnetic waves are extrapolated to the high-frequency region, which enables us to guarantee higher accuracy of reconstruction of the functions of dielectric permittivity for the analyzed structures.     

Sequence Algebra, Sequence Decision Diagrams and Dynamic Fault Trees

A large attention has been focused on the Dynamic Fault Trees in the past few years. By adding new gates to static (regular) Fault Trees, Dynamic Fault Trees aim to take into account dependencies among events. Merle et al. proposed recently an algebraic framework to give a formal interpretation to these gates.In this article, we extend Merle et al.'s work by adopting a slightly different perspective. We introduce Sequence Algebras that can be seen as Algebras of Basic Events, representing failures of non-repairable components. We show how to interpret Dynamic Fault Trees within this framework. Finally, we propose a new data structure to encode sets of sequences of Basic Events: Sequence Decision Diagrams. Sequence Decision Diagrams are very much inspired from Minato's Zero-Suppressed Binary Decision Diagrams. We show that all operations of Sequence Algebras can be performed on this data structure.