In article the algorithm of calculation of systems with unilateral constraints with the replacement reactions of the supports on the force variables. The calculation algorithm is based on the finite element method in the form of the classical mixed method. The algorithm of search of version of the working constructive scheme is based on the modified "physically obvious" algorithm of design constructively nonlinear systems. The paper describes the features of the resolution system of the algorithm proposed by the authors and provides a flowchart. A comparative analysis with the algorithm of calculation of systems with unilateral constraints, proposed by the authors earlier, as well as some others. The efficiency of the algorithm is tested on numerical examples.The advantages of the proposed algorithm are: The vector of results includes the reaction of the support, which allows you to make a decision to change the design scheme; the calculation takes into account, as an additional loading factor, the size of the displasement in the realized one-way support, which increases the accuracy of the calculation.
Keywords: structural mechanics, single-sided supports, structural nonlinearity, the mixed form of the finite element method
The technology of oil production includes a large number of processes in its cycle; extraction is one of the most energy-intensive processes before distillation of miscella. Analysis of automated extraction control methods determines the optimal process control method, which allows to improve the quality of miscella and save product consumption.
Keywords: automated, miscella, extraction, control, system, analysis, method, flow, solvent, quality
The generalized approach of statistical processing of results of fatigue tests of samples on the basis of a choice of numerical characteristics of parameter of static durability, processing of results of fatigue tests with use of methods of mathematical statistics, construction of a fatigue curve according to the linear regression analysis of mechanical characteristics of materials of designs and machines, definition of parameters of function of distribution of a limit of endurance by results of processing of diagrams of step change of loading is offered.
Keywords: Static strength, cyclic strength, reliability, mechanical properties of materials, endurance limit, mathematical statistics, linear regression analysis, method of step change of load, test planning
The article deals with mathematical modeling of thin-film materials production, based on the solution of multi-criteria optimization problems by convolution criteria. The method of estimation of coefficients in linear convolution is presented. The mathematical model developed by the authors allows to calculate the maximum profit of the enterprise from the production of thin-film materials, taking into account the cost of their production.
Keywords: thin film, substrate, production, mathematical modeling, multi-criteria optimization, convolution of criteria
Based on Dual-Phase-Lag theory a mathematical model of heat transfer in a rod was developed. During the derivation of the differential equation, the modified Fourier law was used. Analysis of the calculation results made it possible to determine the dependence of the optimal rod length on the intensity of heat transfer from its side surface.
Keywords: heat transfer intensification, third kind boundary conditions, temporal nonlocality, Dual-Phase-Lag theory, finite-difference method
A methodology for the study of associative memory devices and systems in the environment of functional-logical modeling MatLab / Simulink and the development tools of programmable logic integrated circuits is proposed. To this end, it is proposed to implement the typing of the representation and modeling of such devices and systems by implementing the characteristics of the representation and organization of network associative structures in the modeling environment.
Keywords: Associative memory devices and systems, functional and logical modeling
The article considers the solution of the problem of determining the dynamic characteristics of the relative humidity sensor, the mathematical model of which was based on the first order aperiodic link. The solution algorithm consists in minimizing the value of the standard mismatch of the approximating function and the set of experimental data. The results of processing experiments with the DHT-22 temperature and humidity sensor are presented. The sensor was placed three times in a medium with high humidity, which allowed to obtain an average experimental transient response. The period of measurement and registration of humidity and temperature was 1.5 seconds. The proposed method of calculating the dynamic parameters of the sensor allowed to determine the value of the time constant and the gain of the aperiodic link for the sensor under study. The obtained dynamic characteristics can be used to form an inverse transfer function for the humidity sensor.
Keywords: capacitive humidity sensor transient response, the sequence of measurements, the time constant, the minimization of the error
The possibility of reducing the excessive strength of self-compacting high-strength concrete for use in general construction was investigated. As a cement for such concrete, a cement-ash binder was studied, part of which was replaced by an inert mineral additive - microquatz, obtained by grinding quartz sand. It was established that the studied additive at a dosage of up to 30% does not allow to reduce the strength of concrete to the values characteristic of general purpose concrete. It has been experimentally shown that the replacement of a part of the binder with microquartz does not significantly affect the initial modulus of elasticity, but significantly reduces the fast-flowing creep
Keywords: high-strength self-compacting concrete, cement-ash binder, inert mineral additive, microquartz, strength, modulus of elasticity, fast-flowing creep
In this paper, the concept of minimal intuitionistic dominating vertex subset of intuitionistic fuzzy graph was considered, and on its basis the notion of a domination set as an invariant of the intuitionistic fuzzy graph was considered. A method and an algorithm for finding all minimal intuitionistic dominating vertex subset and domination set were proposed. This method is the generalization of Maghout’s method for fuzzy graphs. The example of finding the domination set of the intuitionistic fuzzy graph was considered as well. The considered method and algorithm can be used to find other invariants, in particular, externally stable set, intuitionistic base and antibase of the intuitionistic fuzzy graphs.
Keywords: intuitionistic fuzzy set, degree of belonging, degree of non-belonging, fuzzy relation, intuitionistic fuzzy graph, intuitionistic fuzzy graph of the first kind, domination set, algorithm, disjunctive member, adjacency matrix
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
The article presents the algorithm of the step method for determining the limit loads for elastic-plastic rod systems. The development of the iterative process with the hypotheses used is given, taking into account the influence of the moment and longitudinal force on the limit state of individual sections, the lenght of the plastic deformation zones along the lenght of the rod. The advantage of the step-by-step method for determining the limit loads in rod systems in comparison with the "direct method " of A.R.Rzhanitsyn is demonstrated. The functions of forms depending on the type of section in explicit form are defined; the algorithm of tabulation of the form function is developed.
Keywords: slab and pile foundation, settlement of the building,stress-strain state,homogeneous anisotropic analog,finite element method
The paper discusses the integral indicators of the quality or level of contamination of natural waters, allowing for an assessment of their ecological status. It has been established that the criterion for the quality of treated wastewater discharged into a water body is a regulatory allowable discharge, but it is not always possible to calculate it, especially for small rivers characterized by low flow rates of the river runoff compared to the flow of wastewater. An integral indicator is proposed for assessing the level of pollution of wastewater discharged, a formula for calculating it, as well as criteria for assessing the quality of wastewater discharged according to the proposed integral indicator. The method of calculating the integral indicator is based on the assessment of the quality of wastewater discharged in terms of BOD5, dissolved oxygen, and nutrient elements. Using the wastewater discharged from the Novocherkassk wastewater treatment plant as an example, an integral indicator of the level of contamination was calculated, which made it possible to characterize the wastewater discharged as “dirty” and make a conclusion about the need for additional treatment.
Keywords: wastewater, water pollution level, integral indicator of water quality, sewage treatment facilities
The article describes the work of the lattice of the tower on the example of the support of cellular communication. The analysis of the distribution of internal forces in the elements of the lattice tower support, depending on the type of connecting grid, taking into account the direction of the wind load on the face or edge structures.
Keywords: cellular tower, steel tower, lattice tower, lattice, belt, brace, wind load, internal force, stress-strain state, stress
The article deals with the problem of imperfect design of modern bridge structures in Russia, using the example of comparing different forms of a continuous profile of bridges. Examples are given where the use of a curvilinear form would save space on the construction of bridges. A number of calculations and their analysis were carried out, as a result of which we received that the parabolic shape of the longitudinal profile of the bridge is the most efficient and economical
Keywords: construction, bridge, longitudinal profile, slope of the embankment, efficiency, efficiency, transverse profile of the embankment, length, volume
An experimental study of a transistor generator with varicap rearrangement has been carried out. A schematic diagram is given, a brief description of the construction and an experimental technique are given. As the results of the experiment are given: • frequency dependence on control voltage (modulation characteristic) • dependence of power on control voltage (parasitic amplitude modulation) • output spectrum in the 500 MHz band
Keywords: FM signal generator, voltage-controlled oscillator, modulation characteristic, output spectrum, transistor oscillator