Effect of ball milling parameters on the particle size in nanocrystalline powders

A model describing the mechanical comminution (ball milling) of crystals to nanocrystalline powders is proposed. It is shown that a fraction of the energy deposited in the processed material is spent for the creation of microstresses ?, which slows down the comminution process.     

Role of the Purification Filter in Maintaining Water Coolant Quality in the First Loop of Marine Nuclear Power Systems

The effect of the purification filter for the first-loop water coolant in marine nuclear power systems on maintaining the regulated indicators (pH, ammonia concentration, chlorides, iron, and the total specific activity of radionuclides) at a prescribed level is examined. It is shown that constant operation of the purification system does not guarantee reliable accident-free operation of the nuclear power system. The operating regulations for the system should be changed as follows: purification is used on the removed cooled nuclear power system with small deviations of the content of chloride ions or in the process of stopping the nuclear power system if it is necessary to remove the loop the radionuclies contained in the surface deposits. __________ Translated from Atomnaya Energiya, Vol. 99, No. 5, pp. 372–376, November, 2005.     

Formation and Optical Properties of Locally Strained Ge Microstructures Embedded into Cavities

Semiconductors - The formation of locally strained Ge microstructures (microbridges) on silicon-on-insulator (SOI) substrates embedded into cavities and the results of studies of the optical...     

Effect of Chemical Composition and Structure on the Shape Recovery Temperatures of Titanium Nickelide-Based Alloys

Metallurgist - It is shown that the structure of alloys based on titanium nickelide, obtained by industrial technology, invariably contains titanium-rich phases of type Ti2Ni/Ti4Ni2(O, N), even if...     

Visualization of “cracks” in steel using ferrite-garnet magneto-optical films with easy-plane anisotropy

Results of nondestructive testing of “cracks” in standard steel samples using magneto-optical ferrite-garnet films with the easy-plane anisotropy are given.     

Preparation and microstructure of VC0.875 nanopowder

Nanocrystalline VC_0.875 nonstoichiometric vanadium carbide powder has been prepared by high-energy milling. The crystal structure, microstructure, morphology, and particle size distribution of the starting and milled powders have been studied by X-ray diffraction, laser diffraction, and scanning electron microscopy. The particle size of the VC_0.875 nanopowder has been calculated as a function of milling time in a model of the milling process. Comparison of experimental data and calculation results demonstrates that 10-h milling of vanadium carbide powder with an average particle size 6 μm yields nanopowder 40 to 80 nm in average particle size.     

An experimental investigation and modelling of the thermodynamic properties of isobutane–compressor oil solutions: Some aspects of experimental methodology

This paper presents experimental data for the solubility, density and capillary constant for solutions of natural refrigerant isobutane with commercial mineral compressor oil Azmol over a wide range of temperatures and concentrations. Based on information for the capillary constant, the surface tension of the solutions isobutane/Azmol is determined. The experimental data were obtained in the temperature range from 303 K to 363 K and at pressures up to 1.7 MPa using static methods. The experimental data obtained for the solutions of the natural refrigerant isobutane with the commercial mineral compressor oil Azmol are sufficiently described with the help of correlations based on the theory of thermodynamic similarity. The paper reports variation of the vapor pressure, density, capillary constant and surface tension as a function of concentration for the isobutane/Azmol solutions. The enthalpy of liquid phase of the isobutane/Azmol solutions is calculated. The analysis of the behaviour of the excess thermodynamic functions is carried out. The paper examines experimental and methodical uncertainties in the investigation of thermodynamic properties of the refrigerant/oil solutions (ROS). The influence of the time taken to establish thermodynamic equilibrium in the experimental cell on the uncertainty of the experimental data for gas-saturated mixtures such as ROS is discussed. Information about the changing concentration of refrigerant in the liquid phase of the ROS and in the surface layer of the liquid phase of the ROS at increasing temperature is presented. In addition, the experimental data for the density, surface tension and refractive index of the mineral compressor oil Azmol are reported.     

Design of correlation filters for recognition of linearly distorted objects in linearly degraded scenes

Generalized correlation filters are proposed to improve recognition of a linearly distorted object embedded in a nonoverlapping background when the input scene is degraded with a linear system and additive noise. Several performance criteria defined for the nonoverlapping signal model are used for the design of filters. The derived filters take into account information about an object to be recognized, disjoint background, noise, and linear degradations of the target and the input scene. Computer simulation results obtained with the proposed filters are discussed and compared with those of various correlation filters in terms of discrimination capability, location errors, and tolerance to input noise.     

Impact of gender, age and experience of pilots on general aviation accidents

General aviation (GA) accounts for more than 82% of all air transport-related accidents and air transport-related fatalities in the U.S. In this study, we conduct a series of statistical analyses to investigate the significance of a pilot's gender, age and experience in influencing the risk for pilot errors and fatalities in GA accidents. There is no evidence from the Chi-square tests and logistic regression models that support the likelihood of an accident caused by pilot error to be related to pilot gender. However, evidence is found that male pilots, those older than 60 years of age, and with more experience, are more likely to be involved in a fatal accident.     

The influence of the high-temperature coolant purification system at nuclear power stations equipped with VVER-1000 reactors on the formation of dose burdens

It is shown that the effectiveness of using high-temperature filters for purifying the coolant at nuclear power stations equipped with VVER-1000 reactors is mainly determined by the precipitation constant of activated corrosion products dispersed in the coolant.