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  • Restoration of bearing capacity of reinforced concrete structures in conditions of constant soaking

    Restoration and strengthening of building structures damaged during operation in conditions of constant soaking and aggressive influence of liquids. On the example of the overhaul of the floor structures of the premises and tunnels of the champagne factory "Abrau-Durso" were shown the most effective and technological ways to strengthen the load-bearing structures.

    Keywords: shotcrete, concrete, reinforcement, bearing structures, reinforcement, bearing capacity, shotcrete, reinforcement, corrosion, repair, finishing

  • Strength characteristics of heavy-weight and sand basalt-fiber concretes

    The main features of the technology of continuous basalt fiber production at the «NPO Vulkan» (LLC, Perm, Russia) are given. As raw materials the study has been used CEM I 42,5 N (activity 45,1 MPa), natural sand with a fineness modulus of 2.3, gravel of dense gabbro-igneous rocks (size up to 20 mm), basalt fiber length of 6 mm and diameter 11 microns production "NPO Vulcan" (LLC, Perm, Russia). The results of determining the ultimate strength in compression and bending of fine-grained and heavy concrete without the addition of basalt fiber (control composition) and with the addition of fiber 0.1-0.9% by weight of cement are described. It is shown that the optimal limits of the introduction of fiber into the mixture of sand concrete can be considered 0.1-0.2% by weight of cement, which leads to an increase in compressive strength up to 70% and bending strength up to 35%. A further increase in the fiber content to 0.9% leads to a decrease in compressive strength to 27% compared to the control values.

    Keywords: basalt fiber, sand concrete, heavy-weight concrete, fiber concrete, continuous fiber, optimization, disperse reinforcement

  • Application of simulation models to the IC parameters testing of pulse voltage converters

    The paper reveals data on the development of simulation models of integrated circuit pulse voltage converters for applying in automated measuring equipment used in the tests of integrated circuits. The integrated circuit of switching voltage converter LM2676 was simulated taking into account heat generation and taking into account the mutual influence of crystal temperature on external electrical characteristics as part of a general behavioral model.The authors obtained results and dependences, coinciding with the experimental data and with the SPICE model at the transistor level, that reflects the influence of the crystal temperature on the the chip operation. In addition, the authors consider a possibility of using behavioral models as a source of reference information in the process of testing electronic components.

    Keywords: ATE, integrated circuit (IC) testing, switching voltage converters, behavioral model, VHDL-AMS

  • Fixed-wing UAVs navigation in the presence of wind: a survey

    Innovative organizations have begun to use fixed-wing Unmanned Aerial Vehicles (UAVs) for healthcare delivery since they can fly faster and provide a proper solution in locations with difficult access or unsafe to human life. Moreover, they assure greater utility and better cost effectiveness than manned aircraft. However, the wind affects both the longitudinal and the lateral variables of the fixed-wing UAV contributing to its nonlinear and due to such external disturbances the UAV can fail its mission. Therefore, this review paper discusses on effects of wind disturbances on navigation of fixed-wing UAV. Full nonlinear equations of motion by including the effects of the wind on the fixed-wing UAV performance are developed. Also an overview of different approaches is presented.

    Keywords: Unmanned aerial vehicle, fixed-wing UAV, navigation control, wind disturbances

  • The situational center as the instrument of management of education in the region

    In article the situational centers operating in the territory of Russia in the educational sphere are considered, their classification is offered and need of expansion of functionality of their activity is revealed. The structural model of the innovative situational center within the certain region allowing to carry out processing of big data arrays that will increase efficiency of decision-making process in crisis situations is developed. This model is universal and applicable to any region.

    Keywords: situational center, education, model, region, information systems, management, digitalization, information system

  • Influence of grain composition and technology on the properties of fine-grained fiber-reinforced concrete using volcanic ash

    The composition of fine-grained fiber-reinforced concrete using Portland cement, stone crushing waste, volcanic ash and basalt fiber are considered. It was revealed that with an increase in the ash content in cement, the compressive and flexural strength of fine-grained concrete decreases, and the water absorption increases. Without a significant reduction in the properties of fine concrete, you can enter no more than 10% of volcanic ash.It has been established that with an increase in the content of large fractions of aggregate, the compressive and flexural strength of fine-grained concrete increases as a result of a more compact arrangement of sand grains. The increase in the content of fine sand fractions reduces the strength characteristics of concrete, and increases water absorption. The dependence of the properties of fine-grained fiber-reinforced concrete on the method of mixing the mixture and molding products

    Keywords: portland cement, stone-breaking wastes, volcanic ash, basalt fiber, grain size distribution, fine-grained fiber-reinforced concrete, bending strength and compression, method of mixture preparation, method of molding products

  • Identification of concrete properties in beam type structures with defects based on dynamic methods

    The task of identifying the properties of concrete and the location of damage in the layout structures of the beam type based on the application of experimental vibration analysis is considered. As a simple analysis model, beam constructions are defect-free and with defects. Based on the experimental approach, the model oscillations with shock and vibration excitation are analyzed. Based on analytical modeling, the dynamic modulus of elasticity, the speed of sound in the beam, the location of the defect are calculated. A technique and an example of determining the location of a defect in beam-type structures is presented. The article was published as part of the implementation of the program of the International Forum "Victorious May 1945"

    Keywords: vibration diagnostics, identification, beam type construction, defect, experimental approach, analytical modeling, vibration excitation

  • The use of plates of non-combustible basalt insulation ROCKWOOL for thermal insulation of external walls and increase the plasticity of the facades of buildings

    The possibility of using an effective insulation of rigid slabs of non-combustible basalt insulation ROCKWOOL not only to ensure the thermal properties of the outer walls, but also to improve the plasticity of the facades of buildings, due to the device protruding on the facade of vertical pilasters, horizontal belts, volumetric geometric patterns using the facade system ROCKFACADE. According to the results of the study on this topic, the conclusions are given.

    Keywords: effective insulation, non-combustible mineral wool ROCKWOOL insulation, outer wall, plastic, building facade, pilasters, belt, ROCKFACADE

  • Study of the structure of the contact zone in concretes with combined aggregates

    The results of the investigation of the structure of the concrete, modified by the additive expanding, on the combined aggregate, which is a natural crushed stone mixed with crushed concrete, are presented. The study of the properties and regularities of the formation of the concrete structure is simultaneously a method of controlling their production. Regularities and reasons for the change (decrease) in the quality indices of concretes with a combined aggregate are established. Investigation and normalization of the properties of concretes on combined aggregates will allow using them along with traditional structural concrete.

    Keywords: recycling, combined filler, contact area, structure, defects, durability

  • Comparison of cold hardiness performance of heavy concrete class B35 obtained by vibrating and centrifuging

    By centrifuging it is possible to manufacture a wide range of building structures and products from reinforced concrete. Such products have several advantages, being relevant in modern construction, however, it requires careful compliance and quality control of the process. The frost resistance of concrete is one of the main indicators characterizing the durability of such building structures as reinforced concrete pillars of power transmission lines and contact network. The analysis of the literature and a series of experimental studies in the laboratory. The influence of the technology of manufacturing products from heavy concrete on the indicator of their cold resistance has been identified and determined.

    Keywords: Racks of power transmission poles, racks of supports of the contact network, centrifugation, vibrating, frost resistance, heterogeneity of concrete, variotropy

  • Experience of using blast furnace slag as an artificial foundation for the foundation of a building

    The experience of using blast furnace slag as an artificial foundation of the building foundation is considered. In the process of construction and installation works, the displacement of the columnar foundations was revealed due to changes in the initial properties of the blast-furnace slag. The chemical composition of the slag belonged to the group of inert materials. In fact, after layer-by-layer compaction, the process of disintegration of its initial properties began. The analysis of the conducted studies showed that in the regulatory and scientific literature there are no unambiguous recommendations on the use of this material as the base of buildings and structures. The recommendations that are available relate exclusively to its use in road foundations. From experience it follows: the use of slag in construction is possible, subject to confirmation of its compliance with specific construction conditions.

    Keywords: blast-furnace slag, artificial base, layer-by-layer compaction of the soil, hydraulic activity and inertness, modulus of basicity, calcium oxides, manganese oxides, particle size distribution, inert material, chemical decomposition

  • The use of gentle technologies in the reconstruction of cultural heritage

    The use of benign technologies in the reconstruction of a building that is an object of cultural heritage is analyzed on a concrete example. Conclusions on the use of selected technology

    Keywords: cultural heritage, cultural heritage object, preservation of cultural heritage objects, monument, sparing technologies, restoration, soil, consolidation, foundation, foundation, deformation, inspection

  • Assessment of the impact of low-pressure water storage units on the environment

    The article provides materials for research and assessment of the effect of reservoir hydro-systems on the environment. A detailed analysis of the causes and parameters of the influence of hydroelectric small hydropower stations on the hydrobtological resources of rivers. The results of the study and the assessment of the pollution level of the bottom sediments of the head node of the Kashkhatau HPP are given, which confirmed a slight excess of the permissible concentration level in terms of the content of cadmium and oil products. The main factors influencing the low-pressure reservoirs on the natural environment and on the restoration of fish river resources of small rivers are determined. According to the results of engineering and environmental studies, a comparative characteristic of soil pollution by oil products in relation to the permissible level was established, analyzing the results obtained, it was concluded that the content of oil products in the collected soil samples is within the established standards. A comprehensive assessment of pollution of water resources and soils of coastal water protection zones is given.

    Keywords: reservoir waterworks, small hydropower plant, aquatic and biological resources, solid runoff, river pollution, flood waters, background concentrations, heavy metals, hydraulic structures

  • Analysis and systematization of the causes of bridge structures destruction

    The paper presents the classification of the main causal aspects of the occurrence of catastrophes of large-span bridge structures, given with elements of the analysis of actual examples of the destruction of structures of various types. Also are described the innovative developments applicable in the field.

    Keywords: fatigue failure, bridge, large-span bridge, failure of structures, destruction of bridge structures, accident in construction, resonance, wear, aerodynamics of bridge structures, stiffness beam, bolted joint

  • Compensation of additive temperature error of the Hall transducer

    In the article we discuss temperature errors caused by non-stationary thermal processes in a thin-film Hall transducer. When solving the heat conduction equation we show the significant influence of effects of Peltier and Seebeck on the Hall voltage measurement results in the current switching mode. A new twenty-step switching currents algorithm for the Hall transducer is proposed. In this algorithm the additional voltages are measured at the absence of current through the transducer. From the additional voltages we estimate the contribution of the temperature drift. It was experimentally shown that for the PHE602117 converter the additive temperature error decreases by 30 times in comparison with the four-step algorithm while reducing performance by 20%.

    Keywords: Hall transducer, additive error, Peltier effect, non-stationary processes, thermo-emf., magnetic measurements, current switching