The article is devoted to the study of curves that are not representable by the intersection of two surfaces. In modern architectural practice, they very often depart from classical forms, replacing them with complex surfaces. Recently, there has been the development of such an architectural style as architectural bionics or bio-tech. Faced with the challenges of sustainable development and its impact on the environment, the construction sector faces the necessary need for innovation. Architecture is presented as one of the promising areas of knowledge use based on biological research. And it is able to respond to current environmental problems. Indeed, many species of animals and plants know how to apply adaptation strategies to the environment and its transformations, forming together with it a sustainable ecosystem. Technological advances in very small-scale observation allow for deeper knowledge of how nature works and offer a new source of knowledge and inspiration for architecture.

Keywords: architecture, spatial curves, axonometric projections of curves, narrowed curves, bionics, biomimicry, eco-innovation

Vector fields in ocean acoustics are the fields of particle velocity and power flow density. Vector analysis methods are used for theoretical analysis and classification of singular points in a hydroacoustic waveguide. Modeling of the power flow field is carried out as a product of the pressure fields and the components of the velocity particle field. The fields of pressure and velocity particles are calculated by the method of normal modes. The simulation of the power flow field in hydroacoustic waveguides with different sound velocity profiles and different acoustic properties of the bottom is carried out. Some regularities in the location of singular points are revealed.

Keywords: hydroacoustic waveguide, pressure field, particle velocity field, power flow field, singular points

TThe modeling of the process of distribution of profile oil pipes in a well by means of a cone punch is considered and the determination of the force necessary for its pushing is carried out on this basis. The normal force for one protrusion of the pipe profile was found. The change in the deformation resistance and profile geometry during distribution is taken into account. The optimal taper angle is determined and the geometric parameters of the punch are selected, including the largest and smallest diameters and its length. A numerical example of calculation based on the obtained formulas is given, which shows the technical feasibility of the process.

Keywords: distribution, oil profile pipes, protrusion force, equilibrium equation, deformation resistance, tool geometry, numerical example

The paper considers a mathematical model of the ion-beam etching process. A nonlinear differential equation of first-order ion-beam etching is considered. It has been established that the model equation for ion-beam etching can be reduced to a homogeneous Monge-Ampere equation. Some classes of exact solutions are presented for this equation. A power-law solution is obtained by the method of functional separation of variables, which depends only on a set of constants and does not contain arbitrary functions. Solutions are also found that linearly depend on arbitrary functions of the coordinate variable and the time variable. Assumptions and explicit conditions are formulated on how to select solutions from the families of solutions of the Monge-Ampere equation that correspond to the model process under consideration. A class of nonlinear equations in partial derivatives of the first order is indicated, which can also be reduced to the Monge-Ampere equation. Limitations on the etching rate are established, which allow the ion-beam etching equation to be reduced to a second-order linear hyperbolic equation, for which, by separation of variables, it is possible to obtain a solution in the form of a Fourier series.

Keywords: ion-beam etching equation, Monge-Ampere equation, model solutions, exact solutions

The water-chemical condition of the steam generators (SG) within the established limits are supporting by a purge. The purge is two kinds they are permanent and periodic. The main idea of the purge consists in taking part of the boiler water from the places of the most likely accumulation of sludge, corrosion products, salts, as well as water purification and its subsequent return to the circuit. The further way of boiler water which is taken from SG is the purge expander. The thermal-hydraulic sketch which is shown in the article and considered to be a mathematic model of the purge expander illustrated level changes in dynamic. Also the mathematic model of automatic control system for purge expander level control which includes a fuzzy governor is presented in the article. Both models are realized with use of software for technique system modelling called SimInTech. The technique implementation of level governor in the SG purge expander realized on the base of the standard software and hardware TPTS-EM which is used as grassroots automation for automatic control system in the technological process of NPP having water-water power reactor which power is 1000 megawatt.

Keywords: reactor, purge, steam generator, corrosion, erosion abrasion, heat carrier, purge expander, governor, model, fuzzy logic, level, pressure, consumption

The paper proposes a model of a circuit with a pulsating circulation of a liquid coolant for cooling an oil transformer and investigates the dependence of the heat transfer coefficient on the frequency of the liquid pulsation in the heated circuit. As a result of the experiments, it was found that the pressure amplitude remains practically unchanged up to a frequency of 0.45 Hz, then sharply decreases and at a frequency of 0.9 Hz it is approximately 12.5 kPa. It was also found that in the heated circuit (circuit 1) the temperature difference exceeds the temperature difference in the heating circuit (circuit 2), which is due to the fact that the fluid flow rate in the heating circuit exceeds the flow rate in the heated circuit. The theoretical calculation carried out showed that in the proposed model the heat transfer coefficient reaches its maximum at a pulsation frequency of 0.6 Hz and is 133.675 W/m2K.

Keywords: energy efficiency, oil transformer, heat recovery, heat exchanger, transformer cooling

The paper considers theoretical studies of the deformed state of the nagel joint with claw washers in LVL structures (from the English LVL – Laminated Veneer Lumber). A mathematical model of snow load has been developed. The method of theoretical calculations of creep from the action of periodic load on the basis of previously performed experiments is given.

Keywords: claw washer, LVL, connection, deformation, mathematical model, load, regression equation, humidity, creep

The regulation of the stress-strain state of the floor slab is considered in order to choose the optimal design solution for the frame of a unique building. Three variants of design solutions with varying reinforcement of the plate and cross sections of the vertical elements of the frame are proposed. The numerical experiment was performed by the finite element method using the Lira-CAD software package. To improve the accuracy of the results obtained, calculations were made taking into account the nonlinear operation of materials. The computational model of the floor slab includes physically nonlinear shell finite elements. Nonlinear loading was modeled taking into account the creep of concrete. Based on the results of the calculations, the analysis of the deflections of the floor slab and the consumption of materials was performed. The numerical experiment allowed us to propose an optimal design solution for the frame of a unique building.

Keywords: stress-strain state, finite element method, unique building, physical nonlinearity, deformation law, building frame

The method of numerical calculation of the parameters of the river channel in the arms is given. The method of nonlinear programming for analysis of dissipative systems with concentrated parameters is used. The technique is focused on computer modeling in the environment of engineering package MathCad. The results of the experiment are given.

Keywords: Distribution of water flow, calculation method, multi-node sections of rivers, water flow

The paper considers the problem of bringing vibrations of a flat membrane to rest, controlled by forces applied to the entire area of the membrane and limited in absolute value. Sufficient conditions are given for the initial data of the deviation and velocity of the membrane, under which a complete stop of motion in a finite time is possible. The resting time is also evaluated. The theorem on estimating the eigenfunctions of the Dirichlet problem for the Laplace equation used in the work makes it possible to refine the mentioned sufficient condition in comparison with the work of F.L. Chernousko. In this work, a similar problem is considered, and the method of expanding the unknown control and the corresponding solution in terms of eigenfunctions of the Dirichlet problem for the Laplace equation is also applied. In this paper, the problem of bringing various elastic oscillatory systems with distributed parameters (membrane, rod, plate, etc.) to a state of rest in a finite time is reduced by means of expansion into a Fourier series in the corresponding system of eigenfunctions to the study of the problem of stopping a counting system of pendulums, connected with each other only through the values of external control actions, the sum of the values of which should not exceed in absolute value some given constant. In order to fulfill this limitation, it is necessary to use estimates for the absolute values of the eigenfunctions, normalized in the mean square. In this paper, we use some estimates for the absolute values of eigenfunctions, previously obtained by Eidus D.M. This allows us to refine the results of F.L. Chernousko for sufficient conditions on the initial functions of the oscillatory system, under which we must dampen the oscillations. These conditions consist in the fact that the initial functions belong to Sobolev spaces with certain indices and in the fulfillment of some additional boundary conditions on the boundary of the domain in which the system is defined.

Keywords: control, wave equation, limited distributed force, Fourier method, counting system of harmonic oscillators

The article considers a model for identifying the parameters of an electric motor by the free run-out method by creating a model of acceleration and deceleration processes in the Scilab Xcos environment. The model is based on a simplified model of an electric motor in the form of an aperiodic link of the first order, which is supplemented by a model of a mechanical link connected to the shaft of an electric motor. Taking into account the inertia of electromagnetic processes makes it possible to adequately model the state and parameters of the electric motor. Identification allows you to determine the moment of inertia of the mechanical part of the electric motor. The model is based on a system of differential equations describing the dynamics of the processes of acceleration and braking of an electric motor. The scheme of the model includes blocks for solving a system of differential equations and blocks for calculating an identifiable parameter. Simulation modeling was carried out in the Scilab Xcos environment to evaluate the functionality of the resulting model scheme. The values of the desired moment of inertia are calculated from the beginning to the end of the simulation process, and the correct value is obtained, with the exception of a short section at the beginning of acceleration. The obtained graphical dependences allow us to visually illustrate the process of acceleration and deceleration of an electric motor in the form of transient functions for torques.

Keywords: electric motor, moment of inertia, electromagnetic moment, run-out method, parameter identification, torque, model diagram, transient function

The paper proposes a theoretical model of self-oscillators based on resonant tunneling diodes. Numerical modeling of the synchronization band of the oscillator was carried out on its basis. The effect of spreading resistance and resonator inductance on the synchronization band is analyzed. It is shown that at a low quality factor, as well as taking into account the nonlinearity of the capacitance and auto-bias, the frequency characteristics of the self-oscillator will be asymmetric and the instability regions of synchronous stationary oscillations will have a complex shape.

Keywords: theoretical model, numerical simulation, quality factor of an oscillatory system, synchronization bandwidth, capacitance nonlinearity, auto-bias, frequency characteristics, instability region, spreading resistance, resonator inductance

This article discusses a new method for adjusting the ground speed of a multicopter-type unmanned aerial vehicle and the initial, previously planned trajectory of its movement, taking into account horizontal stationary wind flows. The use of this technique for local rescheduling of the trajectories being worked out makes it possible to reduce the probability of loss of stability and controllability of such a device, as well as to reduce energy costs when driving in conditions of significant winds with an acceptable deviation from the initial trajectory. The developed algorithm is the basis for the synthesis of more accurate algorithms for local correction of the initial trajectory of motion in a complex field of wind speeds. The efficiency of the algorithm is confirmed by the physical correctness of the simulation results.

Keywords: unmanned aerial vehicle, wind load, stability and controllability of the vehicle, local adjustment of the planned trajectory, reduction of energy costs

The results of clinical trials are the main source of information in the implementation of medical activities in accordance with the principles of evidence-based medicine. At the moment, there are no information systems that would allow a doctor to select clinical studies within the framework of nosology that best match the profile of a particular patient, in order to further analyze their results and select therapy. The aim of the study was to improve the existing process of searching for clinical trials by using the prioritization method according to the inclusion criteria set by the doctor during the selection. To achieve this goal, the following tasks were implemented, namely, the process of selecting and searching for clinical trials by doctors was studied and the method of searching for clinical trials by doctors and the allocation of the necessary criteria was worked out. The team of authors proposed an algorithm for searching for clinical trials according to inclusion criteria, which in turn will significantly increase the effectiveness and reduce the time for searching and choosing therapy.

Keywords: clinical studies, criteria search algorithms, criteria search methods, including factors, search for the nearest class, services

Modern methods of determining the parameters of the tool do not take into account all the features of deep loosening, first of all, such important indicators of the quality of soil decompression as the degree of crumbling and the configuration of the loosening zone. Therefore, the search for a solution to the problem of assessing the quality of soil decompression at the design stage, depending on the parameters of the working bodies of the deep miner and the specified physical and mechanical characteristics of the soil is an urgent task. The aim of the work is to develop an algorithm for assessing the influence of the parameters of the upper reformers on the quality of crumbling and the loosening zone based on modern mathematical and simulation modeling technologies. This is achieved by developing a method for determining the parameters of the loosening elements of the deep miner on the basis of modeling the processes of interaction of loosening elements with the soil, taking into account factors that determine the quality of decompression and the energy intensity of the decompression process of the cultivated soil.

Keywords: mathematical modeling, deep loosening, soil loosening elements, calculation algorithm, degree of crumbling

Global Positioning System (GPS) data acquisition devices have proven to be useful tools for collecting real-world motion data. The data collected by these devices provide valuable information when studying the vehicle movement parameters. For vehicle modeling, this data is invaluable for analyzing fuel consumption and vehicle performance. The study presents a methodology for developing the driving cycle of special cars, during which the speed profile of a particular type of vehicle is studied, loaded and processed, and noisy data is filtered for the purity of the experiment. The test data for severe operating conditions are analyzed. A city driving cycle has been developed for a special truck concrete mixer truck in the conditions of the city of Tyumen. Estimated fuel economy of the specified vehicle is estimated.

Keywords: driving cycle, fuel efficiency of concrete mixer truck, noisy data, data filtering, GLONASS/GPS

The testing of technique for modeling the local atomic structure and X-ray absorption spectra for zinc ions in an aqueous solution in the presence of arachidic acid has been adjusted. Models of the local structure of zinc with different coordination geometries are considered: planar, pyramidal, tetrahedral, and octahedral. The cases of increasing distances between the zinc ion and water molecules in the plane and in the axial direction are simulated for octahedral coordination. It has been established that the most probable change in the local structure of the zinc environment in solution in the presence of arachidic acid is the removal of water molecules from zinc ions in the axial position and their further replacement with the formation of a bond with the carboxyl group of arachidic acid.

Keywords: arachidic acid, lipid layer, local atomic structure, X-ray absorption spectroscopy, total external reflection, zinc, biomembrane, finite difference method, monolayer

In industrial production, stacker loaders used for loading and transporting goods packed on pallets are quite widely used in warehouse work. Basically, when performing a loading and transport technological operation, the functionality of the stacker is sufficient. When an obstacle appears or pallets are stacked, additional maneuverability is required, as a result of which the overall performance of the loader is lost. As a result of the conducted research, it was found that when bypassing obstacles and laying pallets, the time spent on maneuvering the chassis is up to 13%, while the utilization factor of the loader-stacker in terms of productivity is 0.7. Numerical modeling of the positioning process of the load-handling body of the loading and transport unit was carried out, on this basis, the design of a loader-stacker with expanded functionality was proposed and developed, in particular, the service area increased due to the use of a tripod manipulator and two guide actuators, which reduces the time of the technological operation of loading and unloading pallets in warehouse work. Geometrical, structural and kinematic parameters of the loader mechanism are calculated.

Keywords: numerical simulation, loader-stacker, service area, lifting body, manipulator, hinges, chassis, structural analysis, geometric analysis, kinematic analysis, executive drive, pallet