The paper considers the quasi-stationary motion of a viscous compressible fluid in the gap of a thrust bearing with a nonlinear contour of the support surface of the slider. It is assumed that the slider is stationary, and the guide with the molten surface moves in the direction of narrowing the gap at a time-dependent speed. Well-known equations are used for the solution: the equation of motion of a compressible fluid, the equation of continuity, the equation of state and the equation describing the profile of the molten contour of the support ring. The case is considered for the extreme and non-extreme case, that is, when the parameter of the specific heat of melting tends to infinity and vice versa. As a result of an accurate self–similar solution, the main operational characteristics are determined - velocity and pressure fields, load capacity and friction force. The problem of the stability of the movement of the support ring is also solved. The final stage of theoretical calculation methods is numerical analysis.The analysis of its results showed that the modified design of the thrust sliding bearing, taking into account additional factors, has a bearing capacity value exceeding the standard designs by 8-11% in the range of load-speed modes studied. The coefficient of friction is reduced by 9-13%.
Keywords: quasi-stationary flow, extreme case, metal coating, non-standard support profile, hydrodynamic mode, stability of the guide movement
The effect of a zeolite support on the physicochemical properties of cobalt catalysts was studied on a series of samples with zeolites ZSM-5, HY, and NaX. The catalysts were obtained by precipitation followed by mixing the precipitate with a zeolite support. Their properties were characterized by BET, TPR, TPD-H2, IR spectroscopy. The results of the analysis show that the type of zeolite support affects the specific surface area, reduction of deposited cobalt, and the structural properties of the active component of catalytic systems.
Keywords: precipitated catalyst, cobalt, zeolite, dispersion, specific surface area, active component, synthetic fuel, degree of reduction
When developing the final qualifying paper the problem of choosing the optimal structural concept for bearing and enclosing structures. To solve it, normative technical and economic indicators, variant comparison (trial design) and other methods can be used. The objective of the present study, which is carried out as part of the final qualifying paper, is to search for and develop an algorithm that is understandable for practical use for choosing an effective (in terms of specific consumption) structural concept for a steel truss.
Keywords: optimization, specific consumption, cost value, steel truss, steel structure design, STARK ES, analysis of trusses, optimal structural concept, changing the section type, selection of an effective structural concept
The article discusses the basic principles for choosing multi-purpose design solutions for construction production during a forensic construction and technical expertise, and also presents an algorithm for solving problems of this type. Based on the interpretation of the results of theoretical work and the analysis of judicial practice, a method was obtained that can be used in the conduct of judicial construction and technical expertise to solve the problems of choosing design solutions and materials.
Keywords: judicial construction and technical expertise; building production; design solutions; construction expert; mathematical modeling
It was necessary to develop a filter design option for implementing it on an FPGA in conditions of limited FPGA resources and processing time. Options for constructing filters and sequential optimization of the structure for implementation on an FPGA were considered. Two models were built using the Matlab environment, where the results of signal processing with filters were compared for the same parameters. Simulations have shown that the filters are unique.
Keywords: DSP, FIR filter, pipeline, FPGA
The simplest, most reliable and sufficiently accurate method of dosing bulk products is batch dosing by volume using measuring containers. The article considers a mathematical model of a volumetric dispenser. The combination of several methods of regulating the supply of bulk materials during batch dosing is ensured by building an accurate model of the drum dispenser.
Keywords: mathematical model of a drum dispenser, dosing process, friction, dynamic coefficient of friction, static coefficient of friction, bulk material
The object of the research is the utilization heat exchanger. The purpose of the work is to develop a design of a heat exchanger (HA) used to recover the heat of exhaust gases from a gas turbine unit (GTU) with an increased thermal power. In the process of work, the calculation and numerical modeling of the new design of the heat exchanger was carried out. The result of the research was the design of a gas-air heat exchanger, which requires 6.5% less flow rate of the coolant (exhaust gases) compared to the prototype.
Keywords: heat exchanger, heat utilization, energy efficiency of a gas turbine unit, numerical modeling, gas-air heat exchanger
This article considers one of the parts of the development of a device for determining the magnetic characteristics of ferromagnetic materials with a shape memory effect. A functional diagram of the device has been developed. The operation of the device was simulated and the behavior of the shape memory alloy was studied. The error in determining the magnetic characteristics of the FMSF using the magnetizing setup of the developed device did not exceed 0.25%.
Keywords: magnetostrictive materials, basic magnetization curve, magnetic shunt, magnetic flux
The article considers the results of a study aimed at establishing the constants of enzymatic kinetics of biological treatment of domestic wastewater in low-oxygen bioreactors of the circulating type and proposes methods for calculating such structures using the dependences of enzymatic kinetics Michaelis-Menten. The technological mode of operation of the reactor implies a total oxygen regime of not more than 1.1 mg / l at horizontal flow rates of 0.25-0.3 m/s. The efficiency of wastewater treatment is achieved by increasing the mass transfer of oxygen to the sludge mixture and directly into the flocs of activated sludge, as well as due to aerobic granulation by built-in secondary settling tanks.
Keywords: nitrification, denitrification, activated sludge, aeration tank, granular activated sludge, biological treatment, domestic wastewater, low-oxygen treatment method, energy saving, resource saving, ecology
An algorithm is given for carrying out repair work in rooms where devices with ionizing radiation sources are located (inspection points, X-ray machines, computed tomography devices, mammographs, etc.). All stages of the work are considered: the development of documentation, the conduct of examinations, the implementation of construction and installation works, the commissioning of the object (apparatus). Practical recommendations are given on the preparation of the required design and estimate documentation and repair work. The article was written on the basis of completed research work No. 20-147.
Keywords: construction and installation works, repairs, buildings and structures, ionizing radiation sources, X-ray machines, computed tomography devices, expertise
This work is devoted to the problem of the shortcomings of the current regulatory and methodological literature, which complicate the conduct of construction and technical judicial expertise. On the example of the building in Rostov-on-Don, the shortcomings of the normative and methodological literature in the areas of possible use of modern equipment for the inspection of structures are shown. This lack of the necessary normative literature in the field of non-destructive testing is clearly shown. This article shows the difficulties which experts face due to the indicated shortcomings. Conclusions based on the results of the study are made.
Keywords: cconstruction and technical expertise, normative literature, methodical literature, laser scanners, non-destructive control, masonry
An integrated information-measuring system is presented, which includes: a personal computer, special software, a set of sensors, an analog-to-digital and digital-to-analog converter, which makes it possible to investigate corrosion processes. Some possibilities of using modern information technologies in the workshop on physics and electrochemistry are shown. An experiment was carried out to study metal corrosion and its suppression using a traditional installation and a modified one using modern information technologies.
Keywords: software package, metal corrosion, natural experiment, integrated system, information technology
The article is devoted to the problems of the use of building waste in the demolition of houses, as well as substandard products at housing enterprises. The issues of concrete scrap processing, methods of its crushing to obtain materials that can be reused to create reinforced concrete products and structures are considered. Concrete scrap has been investigated for compliance with requirements for large aggregate for construction works. Compositions based on conventional coarse aggregate, concrete scrap and conventional fine aggregate have been developed. For the compositions, the technological characteristics of the concrete mixture are determined, as well as the physical and mechanical characteristics of the concrete at 28 days of age. The use of such compositions for the production of reinforced concrete structures is justified.
Keywords: concrete scrap, secondary crushed stone, concrete, characteristics of concrete scrap, recycling, construction waste, large aggregate from concrete scrap, application of concrete scrap
The article analyzes the experience of creating and testing a professional development program in the field of manufacturing products from micro-and nanopowders. The program is aimed at solving the problem of the qualification deficit experienced by powder metallurgy enterprises, which has become more acute in recent years The educational program was developed by the Volga State Technological University with the support of the RUSNANO Foundation for Infrastructure and Educational Programs and is designed to train engineering personnel in three areas: process engineers who develop technological processes for the production of powder products, design engineers - developers of technological equipment and production personnel who organize and control the production of metal powder products. A special feature of the program is its modular structure, which allows students to choose an individual learning path. The program includes a general professional cycle and three professional modules, the development of which allows you to form the professional competencies required by specialists. One of the modules is implemented remotely using e-learning technology. The advantage of the program is also a focus on practice: it provides a large volume of laboratory and practical classes, as well as practice at specialized enterprises. To assess the effectiveness of the advanced training program and if necessary to adjust it, the program was tested on a pilot group of students. Testing of the program confirmed its effectiveness and the possibility of successful use for professional development of specialists involved in the development and implementation of processes for obtaining products from metal powders.
Keywords: educational program of advanced training, production of powder metallurgy products from micro-and nanopowders, modular structure, distance learning, electronic training course, practice orientation, qualification deficits
The work is devoted to the search for an optimal design solution for columns of a 16-storey monolithic reinforced concrete residential building with a minimum cost of materials. The modern approach to the constructive solution of high-rise buildings assumes multipolarity at the design stage. Meeting modern requirements determined by human needs, durability and functionality of housing and other parameters, the essential importance of economic indicators is also noted. A special approach to the design stage as an attempt to consider in detail the preparatory stage (the choice of the section and class of concrete columns in buildings made of monolithic reinforced concrete) is justified by the relevance of the problem considered in the article.
Keywords: Reinforced concrete columns, frame calculation, Lira-SAPR, concrete class variation, optimal design of reinforced concrete structures, calculation of a 16-storey building