EXTENSION OF THE RELATIONAL DATABASE AND ITS ALGEBRA WITH ROUGH SET TECHNIQUES

This paper describes a database model based on the original rough sets theory. Its rough relations permit the representation of a rough set of tuples not definable in terms of the elementary classes, except through use of lower and upper approximations. The rough relational database model also incorporates indiscernibility in the representation and in all the operators of the rough relational algebra. This indiscernibility is based strictly on equivalence classes which must be defined for every attribute domain. There are several obvious applications for which the rough relational database model can more accurately model an enterprise than does the standard relational model. These include systems involving ambiguous, imprecise, or uncertain data. Retrieval over mismatched domains caused by the merging of one or more applications can be facilitated by the use of indiscernibility, and naive system users can achieve greater recall with the rough relational database. In addition, applications inherently “rough” could be more easily implemented and maintained in the rough relational database.     

Calculation of Settlers for Irrigation Systems

Power Technology and Engineering - This article describes a new method for calculating settlers for irrigation systems. The proposed method is based on the results of experimental research and...     

High-field galvanomagnetic properties of compensated metals under electron-surface and intersheet electron-phonon scattering (tungsten)

The field and temperature dependence of the transverse magnetoresistivity and the Hall coefficient for single-crystal tungsten with a resistivity ratio _293K/_4.2K varying from 780 to 80800 are measured at temperatures between 4.2 K and 50 K in magnetic fields up to 150 kOe. The role of the static skin effect and the temperature breakdown in the galvanomagnetic properties of the compensated metals is evaluated through experiments with tungsten. The experimental data shows that the galvanomagnetic properties of the compensated metals in the high magnetic fields are not dependent only on the Fermi surface geometry. A substantial role in their formation is played by the processes of the electron-surface and the intersheet electron-phonon scatterings.     

Filter materials for fine cleaning based on metal fibers

Conclusions Permeable materials based on metallic fibers with porous layers sprayed on by the detonation gas method, in tangential filtering of media with ferromagnetic and abrasive impurities ensure fineness of cleaning 1–2 m with comparatively low hydraulic resistance. The application of a magnetic field to material with sprayed-on layer of magnetic alloy made it possible to increase permeability to ferromagnetic particles by a factor of more than 1.5.Translated from Poroshkovaya Metallurgiya, No. 1(325), pp. 77–80, January, 1990.     

Measurement of neutron emission from Ti and Pd in pressurized D2 gas and D2O electrolysis cells

Experiments using high-efficiency neutron detectors have detected neutron emission from various forms of Pd and Ti metal in pressurized D₂ gas cells and D₂O electrolysis cells. Four independent neutron detectors based on³He gas tubes were used. Both random neutrons (0.05–0.2 n/s) and time-correlated neutron bursts (10–280 n) of 100-s duration were measured using time-correlation counting techniques. The majority of the neutron burst events occurred at –30°C as the samples were warming up from the liquid nitrogen temperature.     

Computed tomographic imaging of the coronary arterial tree-use of local tomography

It has been demonstrated previously (see E.L. Ritman and A.A. Bove, in State of the Art in Quantitative Coronary Arteriography, p.67-78, 1986) that coronary artery anatomy can be visualized using high-speed, volume-scanning X-ray CT (computed tomography). In the current study it is demonstrated that local image reconstruction (i.e. the reconstruction kernel is ~2(+) mm long), as distinct from more conventional global image reconstruction (i.e. 200(+) mm kernel length), has the advantage of reducing the need for operator interactive image processing. In addition, the local reconstruction algorithm eliminates the need for recording the X-ray projection data over the full transaxial extent of the thorax because it requires only the X-ray attenuation data over the region of the heart. This latter aspect reduces the dynamic range requirements for the sensors and could reduce total X-ray exposure.     

Hydrogenation preparation of stock for the oil removal process

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 31–32, February, 1990.