Obtaining of Detonation Diamonds from Individual Explosives

Combustion, Explosion, and Shock Waves - A method of obtaining detonation nanodiamonds from tetryl by means of blasting the latter in a water shell with the explosive/water mass ratio of...     

Composition and structure of coatings based on rare-earth zirconates

Coatings based on lanthanum, neodymium, samarium, and gadolinium zirconates have been grown by atmospheric plasma spraying of powders, and their composition and structure have been investigated by scanning electron microscopy, chemical analysis, and X-ray diffraction. The results demonstrate that the chemical composition of the coatings differs from the compositions of the powders they were prepared from. During plasma spraying of Ln₂Zr₂O₇-based powders, the rare-earth oxide vaporizes more rapidly than zirconia. The difference in composition between the powders and coatings decreases as the atomic number of the rare earths increases in going from La to Gd. We have studied the processes that take place in the coatings during heat treatment at a temperature of 1250°C. It has been shown that the major phase in the La₂Zr₂O₇-, Nd₂Zr₂O₇-, and Sm₂Zr₂O₇-based coatings undergoes a defect fluorite–pyrochlore structural phase transition. The La₂Zr₂O₇-based coatings have been found to contain ～5 wt % t-ZrO₂ in addition to the major phase. The Gd₂Zr₂O₇-based coating retained a defect fluorite structure.     

Optical Diagnosis of the Geometry of an Axisymmetric Controlled Nozzle of a Gas-Turbine Engine

Modern aviation industry solves the problem of developing multifunction engines capable of flying both at subsonic and supersonic speeds. An important part in such engines is a variable area nozzle, which allows varying the geometry of the engine exhaust unit and, accordingly, its technical characteristics. This study touches upon an computer vision based optical noncontact method for reconstructing a nozzle shape. The reconstruction requires data recorded by two optical three-dimensional recorders directed toward the inner part of the nozzle when the engine is subjected to ground tests. The diagnosis is complicated by the presence of a hot jet being in the way of the sensor vision, the regime-dependent variation of the nozzle glow brightness, and intense mechanical vibrations. The performed bench tests confirm the efficiency of the proposed method. According to their results, in a low-gas regime, the standard deviation of the diagnosed diameters of the exhaust unit and critical sections for each frame does not exceed 0.3% of the corresponding sizes. The data obtained as a result of this diagnosis can be taken into account when upgrading the exhaust unit of the engine and the thrust control system of a gas turbine engine.

     

Analysis of a conflict between aggregation and interfacenegotiation in Microsoft's Component Object Model

Many software projects today are based on the integration of independently designed software components that are acquired on the market, rather than developed within the projects themselves. A component standard, or integration architecture, is a set of design rules meant to ensure that such components can be integrated in defined ways without undue effort. The rules of a component standard define, among other things, component interoperability and composition mechanisms. Understanding the properties of such mechanisms and interactions between them is important for the successful development and integration of software components, as well as for the evolution of component standards. The paper presents a rigorous analysis of two such mechanisms: component aggregation and dynamic interface negotiation, which were first introduced in Microsoft's Component Object Model (COM). We show that interface negotiation does not function properly within COM aggregation boundaries. In particular, interface negotiation generally cannot be used to determine the identity and set of interfaces of aggregated components. This complicates integration within aggregates. We provide a mediator-based example, and show that the problem is in the sharing of interfaces inherent in COM aggregation     

Phase composition and electrical conductivity of indium tungstate films produced from bilayer structures

Indium tungstate films have been synthesized via oxidation of indium and tungsten layers deposited on crystalline silicon and fused quartz substrates by magnetron sputtering. The structure and electrical properties of the films have been analyzed in relation to the oxidation procedure, which is shown to have a strong effect on the phase composition of the films. The dc conductivity of the films exhibits inverse Arrhenius behavior.     

Effect of Modification of Tetryl Detonation Nanodiamonds on Combustion of Model Paste-Like Propellants

Combustion, Explosion, and Shock Waves - Detonation nanodiamonds (DND) represent a unique material combining the properties of a rather passive diamond core with an active carbon shell. The effect...     

Fundamentals of chemical purification of detonation nanodiamond soot using nitric acid

The paper addresses the chemical purification behavior of detonation nanodiamond soot in the case of using a dilute nitric acid under pressure. The optimal process is found to proceed at 230–240°C, 7–8 MPa, with HNO₃ excess of 200–300% of stoichiometry.     

Phase composition and thermal conductivity of zirconia-based thermal barrier coatings

Atmospheric plasma spraying of powder materials has been used to produce thermal barrier coatings (TBCs) based on ZrO₂ stabilized with 7 wt % Y₂O₃, including coatings doped with neodymium and samarium oxides, for state-of-the-art and next-generation high-temperature gas turbine engines. Doping with neodymium and samarium oxides has been shown to reduce the thermal conductivity of the TBCs by 10–20%. At the same time, changes in the phase composition, crystal structure parameters, and microstructure of the TBCs during heat treatment at the service temperature lead to an increase in the thermal conductivity of all the coatings by 50–70%.