Evaluation of the quality of compacting water-saturated sands by sounding

Various methods of sounding were investigated for evaluating the quality of compacting water-saturated fine and medium sands. A comparative analysis of the data obtained with the data of direct soil sampling was carried out. The given recommendations can be used when preparing the new edition of the building codes for engineering surveys for construction. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 17–20, July–August, 1994     

Propagation of a chemical-reaction wave under UV radiation

The formation and propagation of a photochemical-reaction wave were studied. The condition for propagation is the brightening of reaction products. The wave velocity is in direct proportion to the product of the quantum yield by the light intensity and in inverse proportion to the concentration of an absorbing reagent. The time during which a steady-state regime was reached was estimated. Transition of a photochemical wave to a steady state was analyzed. The influence of a periodic variation of light intensity on wave propagation was studied. Examples of photochemical-reaction waves were considered.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 4, pp. 32–36, July-August, 1996.     

Two–Dimensional Stability of the “Pole” Solutions of the Sivashinsky Equation

The two–dimensional stability of the exact solution of the Sivashinsky equation governing the evolution of a curved flame surface in the hydrodynamic approximation is studied. It is shown that the one–dimensional pole solution of this equation governing a local minimum of the surface is stable with respect to small two–dimensional perturbations. The problem is solved under the assumption that the perturbations are small at a distance from the local minimum. Stable one–dimensional solutions may be used to verify numerical simulation of the surface of a hydrodynamically unstable flame and also to construct two–dimensional solutions of the Sivashinsky equation.     

Characteristics of Microscale Combustion in a Narrow Heated Channel

The characteristics of microscale combustion were investigated by using a microchannel heated by an external source. The inner diameter of the channel was 2 mm, which was slightly smaller than the quenching distance of the stoichiometric methane–air mixture under normal conditions. The effects of the equivalence ratio and the averaged flow velocity on the characteristics of combustion in the microchannel were examined. At a channelwall temperature of 1000°C, flames could be stabilized at equivalence ratios of 0.05–1.9 and mixture velocities up to 150 cm/sec in a Ushaped quartzglass channel. At moderate equivalence ratios and lower velocity conditions within the flammability region, oscillatory combustion was observed. A simple analytical model predicting flame oscillations on the basis of the linear analysis of steady solutions is proposed.     

Linear Accelerator for Multiply-Charged Ions at 8 MeV/nucleon – Injector in the TWA Accelerator Complex

The terawatt accumulator at the Institute of Theoretical and Experimental Physics is in the physical startup phase. A new high-current linear accelerator-injector must be developed to achieve design parameters 10¹¹ particles/sec on target; this injector should give at the entrance of the accelerator ring a heavy-ion beam with current 15–20 mA and energy ~7–8 MeV/nucleon with the required charge-to-mass ratio. To this end, a linear accelerator with rf quadrupole focusing at the working frequency 81 MHz was developed; it will accelerate Al¹¹⁺ or Co²⁵⁺ from a laser source before the synchrotron. The accelerator will consist of two sections. The first section with spatially uniform quadrupole focusing will accelerate the beam up to 1.6 MeV/nucleon. A new structure with rf quadrupole focusing and period length 2 is proposed for the second accelerating section. Preliminary numerical simulation of this structure showed that 7 MeV/nucleon with minimum beam losses and accelerating gradients 3.5 MV/m will be achieved on it. Construction of the first section with spatially uniform quadrupole focusing has begun.