Investigation of mechanical and thermophysical properties of composite materials based on “black binders” with the aim of optimizing the process of their cementing

Optimum conditions for cementing prepared roofing paper are determined and an installation for laying prepared roofing paper as a hydroinsulating roofing carpet is designed.Gomel Polytechnic Institute. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 2, pp. 151–153, August, 1992.     

Studying grain-boundary stresses in copper by the molecular-statics method

Grain-boundary stresses in copper for 60 symmetrical tilt grain boundaries with different orientations of the grain-boundary plane and tilt axis have been calculated by the molecular-statics method with the use of embedded-atom-method potentials of interatomic interaction. It has been established that the grain-boundary stresses are negative for grain boundaries with small excess volumes and increase approximately linearly with a buildup of the excess volume. It has been shown that the increase in grain-boundary stresses is connected with a decrease in the average coordination number of atoms, whereas pairs of closely spaced atoms in the grain-boundary core cause a negative contribution to grain-boundary stresses.     

Application of polyuronides for removing heavy metals from vegetable oils. III. Application of alginic acid, pectic and pectinic acids for demetalization of hydrogenated sunflower oil.

Laboratory experiments have been carried out for the removal of heavy metals from hydrogenated vegetable oils using hydrated polyuronides (degree of swelling from 4 to 12.8 ml/g) such as alginic acid, pectic and pectinic acids. The effect of the type of polyuronide, degree of esterification and oil treatment on the degree of demetalization has been studied. It has been shown that with increase in the degree of esterification of the polyuronide the efficiency of demetalization decreases. The second and third treatment of the hydrogenated oil with pectinic acid resulted in a high degree of heavy metal removal. The possibility of efficient demetalization of hydrogenated oils by treatment with water solutions of pectinic acids has also been demonstrated. The degree of metal ion removal increases with decreasing concentration of pectinic acids in the water solution.     

Specific consumption of liquid biofuels in gasoline fuelled engines

Oxygenated fuels increase fuel consumption due to their low enthalpy of combustion; however, their high antiknock index renders them suitable for use in engines with a high compression rate, increasing their thermal yield. This study evaluated the performance of biorenewable oxygenated fuels (ethanol and isoamyl alcohol) and partially renewable fuels (ETBE: ethyl tert-butyl ether, TAEE: tert-amyl ethyl ether and di-TAE: di-tert-amyl ether) with high degree of purity and in mixtures with automotive gasoline, based on tests with Otto cycle engines. Among the oxygenated fuels evaluated here, di-TAE was found to present the best characteristics of performance, both individually and in mixtures with gasoline.     

Nonlinear dynamics of a plasma torch generated by a laser pulse of large width

Experimental data on the nonlinear dynamics of a plasma torch generated by a laser pulse of large width acting upon a graphite target are presented and discussed. The mushroom shape of the luminous region and the duration of emission observed in experiment are explained by the development of the Richtmyer-Meshkov instability at the carbon plasma-air interface and by the formation of nanoparticles in the plasma expanding into the buffer gas.     

Improving the accuracy of measurements of rotation of the plane of polarization

The feasibility of improving the accuracy of measurement of the angle of rotation of the polarization plane in the application of diffraction methods is investigated. Translated from Izmeritel'naya Tekhnika, No. 4, pp. 32–34, April, 1996.     

Angle measurement by the rolling method

A method of measuring the angle of rotation of the microscope stage of a measuring instrument or of the object being monitored by the method of rolling the measurement disk is proposed. An estimate of the main components of the measurement error is given and methods of reducing it are suggested. Translated from Izmeritel'naya Tekhnika, No. 10, pp. 29–33, October, 1996.     

Artificial abortions in Bulgaria and their prevention

Authors go into one extremely important problem for the family, woman, natality and family planning in Bulgaria. Scarcely during the last years it can be observed a slight reduction of the frequency of induced abortions. The average age of women having an abortion is high--about 30, which shows, that induced abortion is still a method of regulation fertility in intergenetic interval. The rate of those who have induced abortion under the age of 19 in Bulgaria is 7.8 to 53.3%, in Czechoslovakia, 6.7%, in DDR--50.0%, Greece--68%, Hungary--8.9%, Sweden--15.8%. The rate of done again induced abortion is higher, that is a result of bad preventing activities during the first abortion. Similar is the tendency of growing number of unmarried women having an induced abortion, as it is in the other countries: from 16.4% in 1980 to 21.7% in 1987. Bulgaria is on the third place in Europe according to the absolute number of dead cases after abortion (maternity death, after Rumania and USSR). It can be mentioned that in Bulgaria women do not use the most modern and safest devices, medicines for interruption of pregnancy.     

Surface tension nonuniformity effect on fluid distribution in a porous body

Surface forces nonuniformity within the volume of a capillary system for a given structure has been examined in terms of its effect on a wetting fluid distribution. This approach enables the distribution for a porous body with a uniform structure to be quantified using a specific function for the pore volume size distribution. The surface forces nonuniformity effect is illustrated using a fibrous structure impregnated with molten copper.Institute of Materials Science Problems, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, No. 8(368), pp. 66–69, August, 1993.     

Explosion resistance of welded cylindrical titanium shells

Results are provided for an experimental study of the reaction to internal explosive loading of titanium alloy PT-3V welded cylindrical shells filled with air or water. It is established that shell failure develops a strong scale effect in the form of a sharp reduction in explosion resistance with an increase in dimensions. Recommendations are made for weakening the effect of the scale factor and increasing shell explosion resistance. Semi-empirical equations are obtained which are recommended for evaluating explosion deformation parameters for the shell of a cylindrical explosion protection chamber made of titanium alloy.VNIIÉF, Arzamas-16 607200. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 4, pp. 148–156, July–August, 1994.