Results of applying the algorithms based on the theory of optimal detection and optimal estimation to analysis of the envelope soliton

The problems on the optimal detection and optimal estimation of envelope soliton parameters have been solved jointly via the quadrature reception method. The expressions for detection characteristics, signal parameter estimates, and relative errors have been derived. It is demonstrated that the false alarm and missing probabilities are usually several percents and the relative errors do not exceed 5–30%. It has been found that the estimated parameters agree well with the real ones if the signal-to-noise ratio is close to unity. The proposed algorithms are shown to have an advantage over the classical and modern spectrum estimation methods when they are employed to reveal the envelope soliton against the background of Gaussian quasiwhite noise.     

Structure,Composition, and Properties of Arc PVD Mo–Si–Al–Ti–Ni–N Coatings

Using an arc physical vapor deposition process, we have produced nanostructured Mo–Si–Al–Ti–Ni–N coatings with a multilayer architecture formed by Mo₂N, AlN–Si₃N₄, and TiN–Ni and a crystallite size on the order of 6–10 nm. We have studied the physicomechanical properties of the coatings and their functional characteristics: wear resistance, adhesion to their substrates, and heat resistance. According to high-temperature (550°C) wear testing and air oxidation (600°C) results, the coatings studied here are wearand heat-resistant under appropriate temperature conditions. Their properties are compared to those of Mo–Si–Al–N coatings.     

Analysis of the Structure of Multilayer Nanocrystalline Coatings Based on Plasma Mass Transfer Parameters Calculated by the Monte Carlo Method

Technical Physics Letters - The results of the simulation of plasma fluxes onto the surface of rotating substrates during the combustion of a vacuum arc of the Cr–Ti–Mo cathode system...     

Radar detection of mini-asteroids

Estimates of the possible early detection of decameter-size space bodies (mini-asteroids) by using the existing non-dedicated and dedicated (space surveillance) radars and also the upcoming radars are presented.     

Heat Resistance,High-Temperature Tribological Characteristics,and Electrochemical Behavior of Arc-PVD Nanostructural Multilayer Ti–Al–Si–N Coatings

The present paper has aimed at studying heat resistance, electrochemical behavior, and tribological characteristics at high temperatures of superhard (~48 ± 2 GPa), multilayered with a modulation period of 17–18 nm, and nanostructured (nc)AlN-(am)Si₃N₄/(nc)TiN coatings obtained with an ion-plasma vacuum arc. The heat resistance of the coatings studied in the temperature range of up to 800°C inclusive was mainly determined by the oxidation of their surface layers without the substrate intrusion. Having a high coefficient of friction from 0.6 at 20°C to 0.8–0.85 at elevated temperatures, the coatings are characterized by virtually no wear, which was confirmed by profilometry measurements of friction zones. The obtained results concerning electrochemical behavior indicate that the Ti–Al–Si–N coatings are highly efficient in the protection of a cutting tool from corrosion in both acidic and alkaline media.     

Hardness,adhesion strength,and tribological properties of adaptive nanostructured ion-plasma vacuum-arc coatings (Ti,Al)N–Mo<Subscript>2</Subscript>N

The properties of nanostructured multilayered coatings of the composition (Ti,Al)N–Mo₂N, which were fabricated by the ion-plasma vacuum-arc deposition (arc-PVD), are investigated. The thickness of coating layers is comparable with the grain size, which is about 30–50 nm. The coating hardness reaches 40 GPa with relative plastic deformation work of about 60%. It is established by measuring scratching that the cohesion destruction character of the coating occurs exclusively according to the plastic deformation mechanism, which evidences its high fracture toughness. The local coating attrition to the substrate takes place under a load on the order of 75 N. The coating friction coefficient in testing conditions according to the “pin-on-disc” layout using the Al₂O₃ counterbody under a load of 5 N is 0.35 and 0.50 at temperatures of 20 and 500°C, respectively. The coating is almost unworn because of the formation of MoO₃ oxide (the Magneli phase) operating as the solid lubricant in the friction zone. An increase in the friction coefficient and noticeable wear are observed with the further increase in the testing temperature, which is associated with the sublimation intensification of MoO₃ from the working surfaces and lowering its operational efficiency as the lubricant.     

Phase composition,structure, and mechanical properties of arc PVD Mo–Si–Al and Mo–Si–Al–N coatings

Using an arc physical vapor deposition process, we have produced nanostructured Mo–Si–Al coatings with a uniform distribution of equiaxed grains 8–12 nm in size and Mo–Si–Al–N coatings with a multilayer structure and a modulation period from 22 to 25 nm. The former coatings consist of MoSi₂ and Mo and the latter consist of Mo2N and amorphous Si₃N₄ and AlN. The hardness of the Mo–Si–Al–N and Mo–Si–Al coatings is 41 and 18 GPa, respectively; they are similar in resistance to elastic deformation; and the Mo–Si–Al–N coating has a considerably higher resistance to plastic deformation. The coatings have roughly identical coefficients of friction (~0.67–0.69 at 20°C and ~0.52–0.56 at 550°C), but the wear resistance of the Mo–Si–Al–N coating is higher by three and two orders of magnitude at 20 and 550°C, respectively. The coatings of the two systems exhibit good adhesion to the substrate and cohesive fracture. Partial wear of the Mo–Si–Al and Mo–Si–Al–N coatings in the course of scratch testing occurs at indentation loads of 80 and 63 N, respectively.     

A Study of the Processes of Structure Formation in Ceramic Coatings by the Kinetic Monte Carlo Method

Technical Physics Letters - The processes of structure formation in arc-PVD Ti–Cr–N coatings are studied by computer simulation methods. A new approach to defining the geometric space...     

Superhard Nanostructured Ceramic–Metal Coatings with a Low Macrostress Level

Technical Physics Letters - The macrostressed state of (Ti,Al)N–Cu and (Ti,Al)N–Ni ceramic–metal coatings obtained by the arc-PVD method has been studied using X-ray diffraction...     

Phase formation in the Ti–Al–Mo–N system during the growth of adaptive wear-resistant coatings by arc PVD

Ti–Al–Mo–N coatings have been grown by arc PVD at different bias voltages, V_b, applied to the substrate and partial pressures of nitrogen reaction gas, p(N₂), in the working chamber. The coatings have a nanocrystalline structure, with an average grain size on the order of 30–40 nm and a layered architecture made up of alternating layers based on a (Ti,Al)N nitride and Mo-containing phases of thickness comparable to the grain size. It has been shown that the phase composition of the coatings depends on V_b and p(N₂): raising the energy of deposited ions by increasing V_b from–120 to–140 V, as well as raising p(N₂) from 0.3 to 0.5 Pa, leads to a more complete molybdenum nitride formation during coating growth, which causes a transition from (Ti,Al)N–Mo–Mo₂N compositions to (Ti,Al)N–Mo₂N. Measurements of the binding energy of Mo 3d photoelectrons in metallic Mo and the Mo₂N nitride by X-ray photoelectron spectroscopy have shown that the transition from the former phase to the latter is accompanied by a negligible energy shift.