Investigation of the possibility of γ-background discrimination in a neutron spectrometer with a proportional counter of recoil protons

The possibility of expanding the range of neutron spectrum measurements to lower energies in fields of mixed n-γ radiation via separation of pulses from recoil protons and γ-induced electrons, using the proportional counter developed for neutron spectrometry at the All-Russia Research Institute of Experimental Physics, has been investigated. With the use of a digital oscilloscope, a data set on the shape of counter pulses under irradiation in a field of mixed n-γ radiation (²⁵²Cf) and in a field of γ rays (SOSGI-M set) has been obtained. Mathematical processing of the obtained data set showed a possibility of distinguishing pulses from recoil protons and electrons; hence, for the ²⁵²Cf source, the lower boundary of the neutron spectrometer operating range can be reduced to ≈80 keV.     

Several chemical transformations of N-(β-hydroxyethyl)uracils

Conclusions Several chemical transformations of N-(-hydroxyethyl)uracils were studied, among them reactions with thionyl chloride and dimethyl sulfate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2811–2812, December, 1968.     

Structure and dynamics of a plasma piston in rail-gun accelerators for solid objects

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 145–150, March–April, 1989.     

Ultimate kinematic characteristics of composite solids accelerated by a magnetic field

The present paper considers the ultimate (under heating conditions) kinematic characteristics of composite solid bodies accelerated by unsteady magneticfield pressure. The accelerated sheet comprises two layers: a layer of a composite material consisting of a mixture of two materials with different electrothermal properties and a homogeneous material layer. The electrical properties of the composite layer with the coordinate are varied along the coordinate by changing the volume concentration of its constituent materials. For an exponential magnetic field rise, an analytical solution is obtained for the problem of determining the optimum distribution of the volume concentration of the composite constituents for which there is a maximum increase in the ultimate velocity of the sheet. Numerical simulation showed that the distribution of the volume concentration obtained from analytical relations is also nearly optimal for pulse shapes of the accelerating magnetic field different from exponential ones. The possibility of considerably increasing the ultimate velocity through the use of composite layers compared to the ultimate velocities for the homogeneous materials constituting the composite is shown analytically and numerically.     

Nonequilibrium effects in the filtration of viscoelastic liquids

An experimental investigation was made of nonequilibrium effects with the filtration of viscoelastic petroleums and polymer solutions. A scheme is proposed to explain the effects obtained. A comparison between theoretical dependences and experimental data confirms the proposed scheme of the phenomenon. The filtration of viscoelastic liquids has recently attracted considerable attention. The interest in it is connected with the discovery of well-expressed elastic properties in several high-viscosity petroleums, as well as with the need to explain the laws governing the movement of solutions and polymer melts in a porous medium, with application to industrial chemical equipment and to the injection of polymer solutions into oil-bearing strata with the aim of increasing the yield of petroleum. Among articles devoted to the filtration of viscoelastic liquids, there should be mentioned the fundamental investigation of Marshall and Metzner [1], me theoretical article of Wissler [2], and me review of Savins [3]. Specifically, it is shown in [1] that, as a result of elastic effects, the filtration resistance in a steady-state flow rises in accordance with the relationship 1+A(V/r)² where V is the filtration rate; r is the mean pore radius; is the relaxation time; A is a constant on the order of magnitude of 10. In [1] this increase in the resistance is explained qualitatively by the action of specific, for elastic liquids, normal stresses in contracting and then expanding pore channels. A corresponding calculation (for a flat channel and a determined nonlinear model of a viscoelastic liquid) was made in [2] using the method of perturbation theory.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 76–83, September–October, 1973.