Information searches on the internet: Conducting thematic searches

This paper describes a procedure for thematic searches on the Internet, including query generalization, restriction, and decomposition. Query decomposition using semantic indexation schemes is considered.     

Analysis of the Possibility of Using Fuel Based on Reclaimed Uranium in VVÉR Reactors

A current problem is to show that reclaimed uranium can be, in principle, brought into the VVÉR fuel cycle. The possibility of using fuel based on reprocessed uranium in VVÉR is analyzed. The requirements for the initial isotopic composition of test batches of fuel pellets with 4% effective enrichment are determined, the compensation coefficient is calculated, the requirements for monitoring the isotopic composition are determined, and the technlogy for fabricating fuel pellets from relaimed fuel is determined. It is shown that the basic neutron-physical characteristics satisfy the restrictions adopted in the VVÉR-440 and -1000 designs. The effect of radiation on the public and the environment as a result of switching to fuel fabricated from reclaimed uranium is the same as for the standard oxide fuel.     

Polymer composite materials: Technologies and applications

The physicomechanical properties of polymer composites based on aramide fibers that are obtained by the wet-spinning technique with the use of epoxy binders are discussed. The chemical structures of reinforcing fibers and components of epoxy binders; the microstructures, surface structures, and some properties of aramide fibers; and the processes of manufacturing high-strength reinforced composites on their basis are described. Some product samples made of these composites are presented. The investigated reinforcing materials possess high tensile strengths and tensile moduli, which make it possible to obtain products with a high level of operational characteristics on their basis.     

A grinding force model allowing for dulling of abrasive wheel cutting grains in plunge cylindrical grinding

A mathematical model is developed for the grinding force in cylindrical plunge grinding that allows for the grinding conditions, the size of the flank wear land areas formed on the grinding wheel cutting grains, the properties of the work material, and the geometrical parameters of the grinding tool and work surface. A formula is obtained for calculating the stock removal rate as a function of the degree of dulling (glazing) of the grinding wheel. The adequacy of the mathematical model of the grinding force in cylindrical plunge grinding is established.     

Femtosecond laser microstructuring in the bulk of diamond

In this paper we report the fabrication of graphitic microstructures in the bulk of diamond using 120-fs-laser pulses at 800 nm wavelength. Polished plates of single crystal diamond and optical quality polycrystalline CVD diamond were used as samples for 3D microstructuring. Under low fluence conditions and focusing a laser beam into the bulk of diamond plates, multipulse irradiation was found to result in the appearance and continuous growth of a laser-modified (graphitized) region from the focal plane towards the laser beam. Controlling the laser fluence and sample translation velocity (scanning beam velocity) allowed high-aspect-ratio ‘graphitic wires’ – microstructures of a few microns in diameter and several hundred micrometers in length – to be fabricated in the bulk of diamond. Physical processes responsible for the continuous growth of microscopic graphitic regions towards a laser beam are discussed. Results of comparative investigations of graphitic microstructures produced by laser pulses of different durations (120 fs and 300 ps) are presented to show the advantages of ultrashort laser pulses in 3D microstructuring of diamond.     

Information searches on the Internet: Targeted searches

Searching the Internet is not as easy as searching in autonomous systems. This is because of the exceptionally high volume of the informational array, the mixed composition and multi-thematic character of Web documents, the improper indexing of information on certain sites, and the dominant purpose of the Internet. For these reasons, information retrievals from the Web are complicated and not very efficient technically.