Home – Home – Jornals – Advanced Search

Viscous liquid film flow along an inclined corrugated (sinusoidal) surface has been studied. Calculations were performed using an integral model. The stability of nonlinear steady-state flows to arbitrary perturbations was examined using the Floquet theory. It has been shown that for each type of corrugation there is a critical Reynolds number for which unstable perturbations occur. It has been found that this value greatly depends on the physical properties of the liquid and geometric parameters of the flow. In particular, in the case of film flow down a smooth wall, the critical wave-formation parameter depends only on the angle of inclination of the flow surface. The values of the corrugation parameters (amplitude and period) were obtained for which the film flow down a wavy wall is stable to arbitrary perturbations up to moderate Reynolds numbers. Such parameter values exist for all investigated angles of inclination of the flow surface.

To improve the efficiency of electrical action on metallic shaped-charge jets, it is proposed to use shutdown of the capacitive storage at the time when the voltage on it during passage of an alternating discharge becomes zero. It has been shown that using this expedient eliminates recharging of the capacitive storage and provides better matching between the current pulse and the time of motion of various parts of the shaped-charge jet through the electrode gap. Studies have been conducted using a computational procedure in which the development of magnetohydrodynamic instability of the jet and the dispersion of its material are considered possible physical mechanisms reducing the penetration capability of shaped-charge jets under the action of high current pulses.

The objective of the work is to test a nickel-chrome alloy as a probe tip material for characterization of discharge plasmas. In order to meet the objective, a symmetric triple Langmuir probe diagnostic system and an associated driving circuit are designed and tested in an inductively coupled plasma generated by a 13.56-MHz radio frequency source coupled with an automated impedance match network. This probe is used to measure the electron temperature, electron number density, and ion saturation current as functions of the input power of the radio frequency source and the filling gas pressure. An increasing trend is noticed in the electron temperature and electron number density with an increase in the input power, whilst a decreasing trend is evident in these parameters with an increase in the nitrogen gas pressure. The overall inaccuracies in electron temperature and electron number density measurements are 5-12% and 3-13%, respectively.

The inverse problem of determining the type and parameters of fastening of the pipe ends from the natural frequencies of the pipe flexural vibrations is formulated and solved for the case of fluid flowing through the pipe. The uniqueness of the solution of the problem is proved, and the Tikhonov well-posedness of the problem is shown. A method for solving the inverse problem is proposed, and examples of the solution are given.

This paper presents the results of experimental verification of Sretenskii's linear theory of gravity waves in a container partially filled with water and oscillating horizontally according to the harmonic law. It has been shown that this theory predicts the existence of an infinite ordered countable set of generation modes of unstable waves. It has been experimentally confirmed that the waves are unstable if the container oscillation frequency is equal to the frequency of any odd standing-wave mode. At even eigenfrequencies of container oscillations, the theory predicts wave amplitudes up to a constant term. Experiment has shown that, in this case, the waves are stable and have minimum amplitudes.

Results of an experimental study and numerical simulation of self-oscillations of a supersonic radial jet exhausting from a plane radial nozzle into an ambient space are reported. It is demonstrated that flexural oscillations develop in the jet, leading to its destruction. Feedback ensured by acoustic waves in the gas surrounding the supersonic jet is found to play a key role in the emergence of self-oscillations.

The state of soil microbial complexes of forest ecosystems of Central Siberia, disturbed by cutting, fires, emissions of pollutants and mining was investigated. The most appropriate indicators for early diagnosis of the condition and sustainability assessment of soils were the contents of microbial biomass, the intensity of the basal respiration and microbial metabolic quotient. Recorded time quantitative and structural-taxonomic restructuring of ecological trophic groups of microorganisms exhibited orientation of the elementary soil-biological processes and allowed detail to assess the state of soils of disturbed forest ecosystems. Successions of soil microorganisms reflected stages of plant succession after cutting. Structural and functional changes in the microbial soil complexes marked by only one-two years after cutting of coniferous forests. For the grassy stage in deciduous young stands, there was an increase in soil microbial activity that accompanied the development of the sod process. Microbiological processes were balanced and comparable to the control at the stage of closed 30-year-old stands. Post-fire recovery of the microbial soil complexes was determined by fire severity and by the properties of soils and vegetation succession. Functional activity of microbial soil complexes were recovered in one or two years after a low-intensity fires, whereas after high-intensity fires - was not recovered in eight years. Indicative responses of soil microorganisms in the sustainable impact of aggressive pollutants tundra zone of the Norilsk industrial region were registered at the functional and at the structural level. In areas of moderate and weak disturbances of vegetation, there were quantitative changes, whereas strong disturbances and constant exposure to pollutants marked structural and taxonomic adjustment of microbial soil complexes, disturbed dynamic processes of synthesis-mineralization and reduced adaptive capacity saprophytic microorganisms as to the existence of low temperatures, and to the effects of pollutants. Successional development microorganisms of dumps of different ages defined as properties of soils, surface slope, and the development of vegetation. Reclamation of dumps with the application of topsoil accelerated the development of meadow vegetation and succession microbial complexes.

Piles of rocks represent the diversity of environmental conditions, which is manifested in the difference of forage and cover conditions. The influence of weather conditions is manifested in a greater degree at the initial stage of formation of ecosystems dumps. The research was carried out on the piles of Borodino brown coal mine section from 2005 to 2014. Data analysis showed a positive correlation of moisture in the area and the abundance of rodents that is not observed for insectivores. The method of correlation analysis showed a weak dependence of population dynamics of small mammals to weather conditions. The study used factor analysis, which grouped the values of population density, diversity, dominance, temperatures of summer and spring, coefficient of moisture, indicators of snow in three clusters. The first cluster combined indicators as diversity and abundance of small mammals. The second cluster combined indicators of moisture in the area, such as summer precipitation and snow cover (snow depth and snowmelt period). The third cluster included the total temperature of the spring and summer period. The description of characteristics of the studied objects in three-dimensional space of factors is obtained. It has allowed revealing of the role of individual indicators on the population dynamics of small mammals.

Experimental recultivation plantations were established in 2001-2003 in three areas allocated depending on the degree of exposure to industrial emissions and the state of woody vegetation in the vicinity of the city of Norilsk industrial region. The first object was the control zone of moderate disturbance, where the vegetation is mostly in normal state - east of the town of Talnakh (Listvyanka river area), the second object is located in zone of strong disturbance (Nalednaya river area, 1 km south of the town of Oganer), and third object of the experimental plantations was established in zone of very strong disturbance of vegetation - at Ergalakh river area (10 km south-east of the city of Norilsk). Experimental plantations were created by planting natural plants (wildings) of Picea obovata L., Larix sibirica L., Rosa acicularis L., Junipeus sibirica L., and different species of willow cuttings using different farming techniques to grow them. In 2008, studies were carried out by state (survival, safety, growth rates) of the created recultivation plantations. The studies have revealed species resistant to industrial emissions in Norilsk region. It has been discovered that survival rates and safety of willow plantings created by cuttings depends on planting technology and site properties. The greatest safety and resistance to industrial emissions were woolly willow Salix lanata L. and Salix hastata L.

To conduct complex research, the system of classification of biological objects was developed and adapted for different nature conditions and forms of anthropogenic impacts. The experience of organization of biological investigations at coal mine dumps and gold-mining polygons, pollutant emissions, operating and developing hydropower station reservoirs was used in the work. The general structure of development of the classification schemes of anthropogenic lands is presented with three generalized specific levels distinguished. The form and intensity of the anthropogenic impacts were used for zoning. Spatial extrapolation and forecast of the anthropogenic impacts are made with respect to the geomorphological state and succession’ dynamics of the anthropogenic habitats. Monitoring and resource estimation are carried out by the succession stages. Quantitative estimation of the structure of the anthropogenic lands is made with a use of moderate- and high- resolution satellite data in GIS. Types of mountain recultivations of coal mine dumps determine three post-anthropogenic succession series/classes: erosion, forest, and steppe. They are divided by groups of types depending on succession stage - from juvenile to closed corresponded to the zonal standards. The type shows stage that is determined by the dominant vegetation. For Norilsk anthropogenic region where there is constant pollutants impact, five classes/zones, four groups of types by geomorphological characteristics and two additional indicators which estimate the presence of dead ground vegetation as well as six types by dominant vegetation were defined. Classification scheme of the impact of hydropower station reservoirs is characterized by three levels of generalization for water and coast surfaces. The basin is divided by classes depending on the width and direction of the dominant winds (open, closed), groups of types depending on depth (deep-, shallow-water), types depending on flowage and stagnation. The coastline is divided by classes of constant marginal erosion, periodical impoundment and climate impact, group of types and types by well-known succession series and stages typical for the coast vegetation.