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  • Modeling of the low-pass filter

    Results of modeling and a pilot study of a low-pass filter with a cut-off frequency of 4 GHz are given. Modeling of the filter was carried out in MicrowaveOffice application program package. The experiment was made on the vector analyzer of RXA chains. Results of modeling and an experiment conform to the imposed requirements, namely: - cut-off frequency is 4 GHz; - losses in bandwidth no more than 3 dB; - an obstacle on the second harmonic of cut-off frequency not less than 60 dB; - wave resistance of an input and exit of 50 Ohms.

    Keywords: low-pass filter; cut-off frequency; losses in bandwidth; losses in an obstacle band; modeling; experiment

  • The calculation algorithm for systems with unilateral constraints with the replacement reactions of the supports on the force variables

    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

  • Calculation of water flow expenditures on multi-layers sites of rivers

    The article discusses the current problems of calculating the distribution of water flow; the problems of current methods based on solving nonlinear equation systems are identified; proposes a new method for solving problems; analysis of the effectiveness of the proposed method; proposed a way to optimize the simulation calculations.

    Keywords: waterways, water expenditures, modeling

  • Building a physician-customized breast cancer classifier using combined thermometry

    We consider the problem of diagnosing breast cancer on the basis of combined thermometry. Diagnosis is carried out using two-dimensional generalized signs. Each such sign is formed on the basis of two one-dimensional. We propose an algorithm for the formation of sets of such features using tapering ellipses. On the basis of a set of such signs a classifier is built. By varying the semi-axes of the ellipses, the physician can control the sensitivity and specificity of the classifier. The doctor can fix the threshold value of specificity and achieve the maximum value of sensitivity. As a result of computational experiments, we built a family of 300 sets of two-dimensional signs and implemented a classifier customized by the doctor.

    Keywords: combined thermometry, diagnostic algorithms, data analysis, algorithm sensitivity, algorithm specificity, logistic regression, custom classifier, breast screening, mammology

  • Development of a method for controlling miscella concentration

    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

  • About some features of planning and statistical processing of results of fatigue tests of samples.

    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

  • Mathematical modeling of multidimensional optimization of production of thin-film structures by convolution criteria

    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

  • Locally - non-equilibrium heat transfer in а rod with forced convection

    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

  • Methods of functional and logical modeling of associative memory devices and systems

    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

  • Dynamic characteristics of the relative humidity sensor

    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

  • Deformation and strength properties of cement-ash concrete with the addition of microquartz

    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

  • Determination dominating set intuitionistic fuzzy graph

    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

  • The effect of dosage of redispersible powders on the properties of fine-grained concrete after repeated freezing-thawing

    The introduction of RPP to 3% by weight of the dry concrete mixture is accompanied by a decrease in the compressive strength of fine-grained concrete aged from 28 days to 37%, and after 75 cycles of freezing and thawing - up to 46%. The decrease in tensile strength in bending at the age of 28 days was 25%, after 75 cycles - up to 23%. The dependence of the initial modulus of elasticity of concrete on the compressive strength remains virtually unchanged after 75 cycles of freezing and thawing. The dependence of the adhesion of MZB to the concrete base with increasing dosage of RPP is ambiguous. The maximum increase in adhesion to the concrete base after 28 days of curing in NU and after 75 cycles of freezing and thawing was 26%. An increase in RPP dosage to 3% leads to a decrease in the initial elastic modulus of MZB to 26% after 28 days of curing in NU and to 32% after 75 cycles of freezing and thawing.

    Keywords: dry building mixes, redispersible polymer powders, adhesion to the base, elastic modulus, tensile strength, freezing and thawing cycles

  • Organizational structure of construction enterprise management and principles of its formation

    Improving the structure of the management apparatus at modern construction enterprises is a necessity in conditions of increased competition in the market of products and services. The size, conditions of work, organizational and legal forms determine the production structure of construction companies. The growth of production leads to the optimization of the organizational structure of the construction company management, corresponding to its goals and objectives. Therefore, there is an increased need to review the existing management structures of construction organizations, which serve as a new modern socio-economic environment. Optimized organizational structures of construction companies and organizations should be easy to manage and be able to adapt to the changing economic conditions of the modern market.

    Keywords: management apparatus, construction production, organizational structure of management, functional divisions of management apparatus

  • 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