The electrophysical and mechanical properties of a piezoceramic material based on CTS are investigated. A number of features in the behavior of the electrophysical properties of the material in the temperature range located significantly below the low-frequency (1 kHz) maximum of the dielectric constant T_m = 160℃ have been revealed. The obtained results indicate the proximity of the studied material to ferroelectric relaxors, in particular, the low coercive field E_c~5 kVcmcm, the significant dependence of T_m on the frequency and amplitude of the measuring field, as well as the behavior of the velocity of longitudinal ultrasonic waves in this ceramic. It is shown that the elastic properties of this material are very close to ferroelectric relaxors, having a high malleability in a very wide temperature range. At the same time, the squareness of the polarization loops at relatively low temperatures indicates the manifestation of the classical properties of the ferroelectric during the polarization switching processes, and not the "freezing" processes characteristic of ferroelectric relaxors. From the results obtained, it can be established that this composition will be promising for use in the actuators of adaptive optics systems and precision positioning devices due to the high values of piezomodules.
Keywords: PZT system, ferroalloy ceramics, dispersion, polarization, elastic properties, blurred phase transitions, curie temperature, depolarization temperature, ferroelectric relaxor, rhombohedral phase, tetragonal phase
This article presents one of the methods for analyzing the chirality coefficient of a medium depending on such parameters as concentration n, frequency f, dielectric constants of both the container material, the medium itself, and left- and right-handed spirals distributed in this material. As a result of this work, the frequency characteristics of the chirality coefficient were obtained at various concentrations of the container trace elements.
Keywords: chiral medium, Telledzhene element, chirality coefficient, dielectric constant of the medium, magnetic permeability of the medium, spiral structure, metamaterial substrate, bulk concentration, metamaterial, spiral inclusions
The article is devoted to the development of models and algorithms for calculating control (advisory) actions when training operators of technological processes (on the example of reloading processes and, in particular, portal cranes) on computer training complexes (CTC). A complex of models and algorithms is proposed, based on which control actions are calculated regarding discrete crane controls and the possibility of moving the load to a target position with minimization of oscillations at the end point is provided. These models and algorithms use variable parameters of the technological process, described by linguistic variables, and customizable characteristics of crane models and engines, which allows calculating control actions depending on the type of crane, the specifics of the technological process, the training methodology used for operators and other significant factors. Application of the advisory system based on the developed models and algorithms promotes to improve the training process for operators of reloading cranes at CTC and, as a result, to reduce the probability of emergency situations, reduce time and energy costs.
Keywords: computer simulator, reloading processes, portal crane, advisory system, control actions, mathematical modeling, fuzzy logic controller
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