This article concentrates on the issues of radio wave propagation in forest conditions. The issue of representing the forest mass as a heterogeneous structure with a low dielectric constant is considered. Calculation and comparison of radio signal attenuation using several empirical models were carried out. It is shown that empirical models take into account the heterogeneous structure of the forest when moving from free space to the forest.
Keywords: radiowave propagation, wooded area, empirical model, radiowave attenuation, path loss, ground mobile communication, electrodynamic characteristics of a heterogeneous structure
The parameters of the porous structure and the active surface of cobalt catalysts for Fischer-Tropsch synthesis (SFT) prepared by the impregnation method have been studied. Characteristics of composition and porous structure were studied using elemental analysis and the Brunauer-Emmett-Taylor method (BET). The effect of the addition of oxide promoters on the specific surface area, pore volume and pore size of the Co / SiO2 catalyst has been studied.
Keywords: Fischer-Tropsch synthesis, heterogeneous catalyst, promoter, carrier, specific surface area, porous structure, selectivity, activity, dipping method
The parameters of the porous structure and the outer surface of cobalt catalysts for the synthesis of Fischer-Tropsch, promoted by magnesium, prepared by the impregnation method according to moisture capacity, were studied. The effect of polymorphic modification (γ, θ, α) of the carrier on the physicochemical properties of the catalyst Co-Mg / Al2O3 was studied.
Keywords: Fischer-Tropsch synthesis, polymorphic modifications of Al2O3, synthetic motor fuel, catalyst, carrier, elemental analysis, BET method, specific surface, porous structure
Three batches of Co-MxOy / SiO2 catalysts were prepared with different methods of introducing an oxide additive. Physicochemical studies of catalysts by elemental analysis and Brunauer-Emmett-Taylor (BET) methods have been carried out. The effect of additives of oxide promoters and the method of their introduction on the specific surface, volume and pore sizes for Fischer-Tropsch synthesis catalysts were studied.
Keywords: Fischer-Tropsch synthesis, carbon-containing resources, catalyst, active component, silicate carrier, Al2O3 and ZrO2 promoters, elemental analysis, BET method, surface area, volume and pore size
The article analyzes the natural conditions of the Northern latitudes of Russia, where the main reserves of fossil hydrocarbons and metals are concentrated. It is shown that mining requires the development of the road network and artificial structures on the roads. It is noted that the most difficult stage in the construction of bridge structures is the construction of foundations. The types used in the Northern latitudes of foundations are considered, and their positive and negative qualities, such as weight, method of construction and volume of earthworks, are noted. The paper emphasizes the relevance of the problem of maintaining the stability of permafrost soils in seasonal thawing and loss of their bearing capacity. Methods of maintaining the soil in a solid state can be natural and artificial. The methods of thermal stabilization of soils, as well as machinery and equipment used in these conditions.
Keywords: permafrost, road network, bridge, polystyrene, superstructure, pile support, Foundation, thermal insulation screen, heat stabilizer
The dispersion parameters of the active component of cobalt catalysts promoted by nickel for Fischer-Tropsch synthesis by the temperature-programmed hydrogen desorption method (TPD H2) were studied. The influence of the polymorph (γ, θ, α) of the support on the physicochemical properties of the Co-Ni / Al2O3 catalyst was studied.
Keywords: Fischer-Tropsch synthesis, biomass, catalyst, support, Ni promoter, polymorphic Al2O3 modifications, TPD H2 method, active surface, dispersity, cobalt crystallites
This article is dedicated to one of the symbols of Volgograd city, which is the Astrakhanskiy Bridge. We described the history of creation and the technical specifications of the bridge over the Tsaritsa river. After conducting an investigation, some defects in the bridge construction were uncovered. The framework arcs have longitudinal cracks, the protective layer of concrete is destroyed; the longitudinal main reinforcement is exposed and corroded. The protective layer of concrete was removed and the longitudinal main reinforcement was corroded on the longitudinal beams. During operation of the bridge, the defects that decrease load capacity and durability appeared: destruction of the protective layer of concrete on a plate of about 2 square meters. This led to the beginning of corrosion of the lower reinforcement net. Steel brackets, holding the walkway slabs, are heavily corroded; the protective paint coating on them is destroyed over significant lengths. The analysis of detected damage allowed to evaluate their impact on the durability and load capacity of the construction and determine those, who are responsible for its occurrence. It is noted that postponing of repair operations has a negative impact on the state of the bridge.
Keywords: bridge, city symbol, superstructure, roadway plate, defects, arch, bridge system, bearing structures, durability, load capacity
The article presents calculation of the cost of overlappings from LSTK and wooden ones. The floors of the two-storey house with a span and overlap with a span of 12 m were calculated. Calculation of the cost of materials is presented for each option. In conclusion, conclusions were drawn on the rational use of material types for each of the calculated spans.
Keywords: light steel thin-walled structures, LSTK ceiling, wooden flooring, reduced characteristics, effective cross-section, construction
The lack of standards for the calculation of lightweight thin-walled steel structures allowed low-quality producers to save on production, which endangered the people who exploited such buildings. The appearance of normative documents for the calculation of thin-walled structures entails responsibility for the affirmers of these normative documents. In Russia, such norms appeared relatively recently and the purpose of this study was to compare domestic normative methods of calculation with non-significant ones. During the presentation of the study, the concept of a reduced (effective) section of a beam when working on bending was considered. Also, the same stages of the calculation methods were noted, indicating the places where the methods differ in their opinions. The result of this study is a comparison table for the basic geometric characteristic for obtaining the bearing capacity of an effective torque element of resistance. An analysis was carried out and a conclusion was drawn on these values.
Keywords: steel structures, light steel thin-walled structures, thin-walled beams, reduced cross-section, bending work, C-shaped profile, effective cross-section, effective area, effective resistance moment
In this paper, it is proposed to update the values of the bearing capacity of the hinge attachment of the beams to the columns on 2 bolts. A comparative analysis of the bearing capacity of the assembly presented in the 2.440-2 release 1 series and calculated according to modern building codes is carried out. Five calculation formulas were obtained for the five possible limiting states of the node. A table with the values of the limiting forces perceived by the connection is presented. A possible variant of improving the assembly is presented, by including a support table in the work.
Keywords: bearing capacity, metal structures, hinged unit, structural solution, connection of elements, limit state
The paper deals with the use of Markov chains apparatus in problems of forecasting the operational status of non-rigid pavements maintained roads in the network layer. An example of predicting the deterioration of structural indicators for the non-rigid pavement of the existing road section.
Keywords: roads, pavement, forecasting, Markov chain
"The paper analyzes the influence of water pollution Azov-Black Sea water basin polychlorinated aromatic compounds (PAC) on health. The literature and reference material on the conditions of formation of ecologically particularly dangerous polychlorinated compounds (dioxins, furans and biphenyls) and their pathways in the environment - air, natural water, soil, sediments and various tissues of biological organisms (including humans). The types and characteristics of PAS effects on living organisms. The analysis allows to see the additional impact of complex human influence adversely affects the morbidity of the population under the influence of mutagenic, carcinogenic and teratogenic effects of polychlorinated compounds. Recommendations to address environmental health and reduce the risk of dangerous diseases and preservation of the gene pool of humanity."
Keywords: anthropogenic load, Azov-Black Sea water pool, toxicology, polychlorinated aromatic compounds (PAC), dioxins, polychlorinated biphenyls (PCBs), mutagenic, carcinogenic and teratogenic properties, preventive measures
In the absence experimentally confirmed data that chloroform in the water after boiling or sedimentation does not disappear, and only switches to other chemical compounds obvious usefulness boiled, and preferably a distance not less than 6 and not more than 24 hours the water to reduce the negative effect chloroform. The study of drinking water quality on the content of chloroform in water treatment soobruzheny distribution network, monitor the change in the concentration of chloroform as a result of sedimentation and boiling, as well as methods of dealing with organic chlorine compounds in drinking water. The objective of the exclusion of the possibility of formation of organochlorine compounds in drinking water can be achieved most effectively through: reduction of organic compounds in source water due to its pre-cleaning before putting chlorine in it; exclusion from the scheme of drinking water chlorine and chlorine-containing agents.
Keywords: chlororganic compound, chloroform, drinking-water, disinfection of drinking-water
The estimation of water quality in the catchment of the city of Taganrog. To estimate the proportion used combinatorial index of water pollution (UKIZV), consider the dynamics of the main pollutants in the water intake area.
Keywords: MPC, UKIZV, water quality, WPI, critical indicators of water pollution, sulphates
The paper presents the results of theoretical studies of the problem assess the impact of structural features in the design phase in the direction of the acoustic antennas. Consider the generalized algorithm of forming directional characteristics of a special form in the application hydroacoustic problems and solutions of the generalized problem of optimizing the characteristics of antennas and modular design principle. Optimization problem proposed to divide into separate components: optimization of antenna characteristics and optimization of tactical performance speaker system that comprehensively affect the choice of antenna design. The method of constructing an antenna with a pie chart in the horizontal plane when the parametric antenna sector review contains some highly directional converters pumping flat aperture.
Keywords: acoustic antenna, directivity characteristic, sector