Voronezh State University

About: Voronezh State University is a education organization based out in Voronezh, Russia. It is known for research contribution in the topics: Silicon & Boundary value problem. The organization has 5166 authors who have published 6097 publications receiving 31680 citations. The organization is also known as: VSU & Voronezh University.

The effect of seed coat color grading on height of one-year-old container-grown Scots pine seedlings planted on post-fire site

Abstract: The basis for the present research is an alternative hypothesis about the existence of significant differences between morphometric parameters of Scots pine (Pinus sylvestris L.) seedlings of different color-seed races. The experiment was established by planting of one-year old Scots pine container seedlings under Kolesov's sword. Ten rows in a 90-fold repetition were planted on 24th October 2017 on the site of the left-bank forestry training Voronezh State University of Forestry and Technologies (coordinates of the nodal point: N 51°49'40.3' E 39°21'49.7', altitude 100.8 m asl). Seedlings were produced from the seeds, previously separated based on seed coat color and size, in the nursery by a standard rotation cycle for Scots pine container seedlings. The planted seedlings were measured for height three times during the first growing season after the field planting on a post-fire site. The results show a significant difference in one-year-old container produced Scots pine seedlings height with white seeds producing the highest seedlings after one year growth in the field. Our results indicate the potential use of seed sorting on seed coat color for improvement of both, production of forest reproductive material and reforestation success.

Structural status of technogenic soils and the development of preferential water flows.

Abstract: A technogenic soil (technozem) created on the surface of the former sludge pond of the Lebedinskii iron-ore quarry in the course of land rehabilitation was studied. The upper chernozemic fill in the technozem was underlain by the sandy or loamy layers. The water regime of this soil differed from the water regime of background automorphic natural soils and was characterized by a periodic stagnation of water at the boundary between the two layers. In 20 years, this type of the water regime resulted in the development of a columnar structure in the lower part of the chernozemic layer. The coatings on ped faces in this part of the profile had an increased content of Fe and Ca ions, and the soil texture became coarser under conditions of the alkaline medium. There was no differentiation of the carbon of organic substances and carbonates in the soil profile. Field studies of water flows in this soil with the use of starch label and laboratory experiments on infiltration of salt solutions through the soil columns with determination of ion concentrations in separate portions of the filtrate demonstrated the existence of preferential water flows in the technozem. Rapid infiltration of water through preferential water paths in the chernozemic layer after abundant rainfalls and during the snowmelt season leads to the development of perched water above the textural boundary. Temporary water stagnation in this zone ensures an increased water content in the intraped mass of columnar peds in the lower part of the chernozemic layer.

Relation between resistivity of concrete and corrosion rate of reinforcing bars caused by galvanic cells in the presence of chloride

Abstract: The article presents the experimental study and theoretical analysis of the relationship between the resistivity of the concrete (ρ) and the reinforcement corrosion rate. The corrosion process was simulated using a galvanic sensor. The distance between the galvanic sensor plates and the sizes of the plates are selected in such a way as to simulate the functioning of microcells in the case of corrosion in the presence of chlorides. Tests carried out on bimetallic galvanic sensor embedded in mortar have corroborated a direct proportionality between the rate of corrosion and resistivity of concrete. The role of ohmic resistance in the corrosion process have been estimated by comparing model calculations and experimental results. The hypothesis of ohmic control the corrosion process in case of microcells was rule out. It was suggested that the process of corrosion is governed by the fraction of metallic surface wetted by porous liquid. A form of the equation for the current in a galvanic cell is proposed, taking into account the above model representations. The proposed approach can be used to simulate the corrosion process of reinforcement in concrete and to assess the effect of the saturation of concrete with moisture on the corrosion rate.

On the possibility of representing an acoustic field in shallow water as the sum of normal modes and quasimodes

Abstract: Using the example of a shallow-water acoustic waveguide with a homogeneous water layer of constant thickness H lying on a homogeneous fluid absorbing half-space (bottom), we obtain estimates of distance r from a source, for which it is possible to ignore the continuous spectrum for the mode description of the depth dependence of the intensity of a low-frequency sound field in the bottom layer. We have compared two discrete representations of the field using (1) the total set of normal modes and (2) the total set of normal modes and quasimodes. It is shown that in the case when there is at least one normal mode in the channel, additional allowance for quasimodes makes it possible by an order of magnitude to approximate the boundary of applicability of mode theory and on average establish it at a level of r ~ H or less. We explain the functional dependences of the contribution of the continuous spectrum to the total field on the waveguide parameters and find the conditions of its minimization. We present examples of description of the field in the bottom, where the advantage of using quasimodes at short distances is also demonstrated.