The problem of analytical synthesis of the control acceleration of an unmanned aerial vehicle (UAV) of a multirotor type is being solved in relation to a light quadrocopter with a high flight duration. The optimal control is analytically determined for a given minimized quality functional in the form of the minimum time required to transfer the UAV from 

a given initial to a given final position in space. A mathematical model of the movement of the UAV mass center in a given plane relative to the earth's surface is considered. A feature of the proposed technique is the solution of the problem of maximum speed (forced control) based on the consideration of the laws of kinematics of uniformly accelerated motion of a rigid body. For given characteristics of the maximum allowable speed and control acceleration of the UAV, the moments of switching of the control signal are analytically calculated, which can be implemented in the UAV autopilot. This allows, in contrast to classical methods for solving the problem of forced control, to get rid of the need to solve a two-point boundary value problem and consider additional transversality conditions. The computer simulation of the obtained analytical results in the form of processes of changing the control acceleration, as well as the UAV motion parameters, has shown the efficiency of the proposed technique and the prospects for its use at the initial stage of the synthesis of the UAV control system.

The paper presents a theoretical analysis of vibrations of a curvilinear  rod in the form of a loop of low rigidity formed from a quarter of a circle with a constant radius, limited by an angle π/2 < γ < π and two rectilinear rods. It is indicated that in the practice of ultrasonic technology, some types of structures are known in which elastic elements are used as resonators, waveguides, oscillation transformers and instruments for influencing the processed materials. Their use makes it possible to obtain an additional impulse of force in the working area by using the potential energy caused by the action of the elastic properties of such elements. However, insufficient attention has been paid to the theoretical justification of the use of elastic elements in ultrasonic systems. In this regard, the present work is devoted to the theoretical  substantiation of the use of an elastic tool made of a thin rod having the shape of a loop. The diagram and calculation of displacements of the free end of a curved rod under the action of forces directed along the longitudinal axis are given in the paper. It is shown that elastic displacements are caused by a curved shape in the form of an arc of a circle of a curved rod. For comparison, calculation schemes of two types of curved rod with an attached rod are given. In the first case, the free ends of the rectilinear rods, directed vertically downwards, make elastic movements along two coordinates. In the second case, the ends of rectilinear rods directed at a certain angle to the vertical axis and converging at the bottom point due to the symmetry of their location, make vertical movements only along one coordinate. The considered shape of the curved rod can be successfully used as a tool for performing technological tasks in the ultrasonic method of processing holes in brittle materials, spot welding, etc. Such a scheme, in contrast to the traditional ultrasonic treatment scheme based on the use of rectilinear rods, makes it possible to increase the magnitude of the vibration amplitude of the instrument due to elastic displacements of the curved section of the rod of low rigidity. The proposed form will increase the intensity of tool vibrations and increase process productivity and processing accuracy. The resulting calculation formula shows that the amount of elastic displacements of curved rods is affected by the cross-sectional stiffness and the radius of curvature of the curved part, as well as the angle of inclination of the rectilinear rod. The theoretical calculation is supplemented by a comparative experimental study of the Chladni forms for both schemes obtained on the sheet surface using abrasive particles.

The object of the research is thermal spray process for the formation of metal coating from bronze powder in plasma-fuel variant, using direct current (DC) electric arc plasma torch, on steel samples. The aim of the work was to investigate and develop the technology for plasma-fuel spraying of functional coatings (for wear-resistant and antimicrobial applications) on machine-building and medical purpose pieces with increased process capacity and moderate energy consumptions in a comparison with conventional thermal spray technologies with use of inert and oxygen-free gas media. During the study, using experimental and thermodynamic estimation methods, the thermal and chemical parameters of the process under the spraying conditions at ambient pressure were characterized, which made it possible to determine the area of preferred regimes of the developed technology. On the modernized testing unit for plasma spraying of metal powders with power of up to 40 kW, operating using a controlled combination of three types of gases – technical nitrogen and propane-butane (LPG) with compressed air, the measurement and optimization of the operating and constructive/assembling parameters of the system for aluminum bronze coating spraying were established. In this case, the experiments were carried out using the designed fuel intensifier, which is joined with the PP-25 arc plasma torch, as well as additional technological equipment (protective shroud). For samples of the resulting coatings with a thickness of 100 to 450 mm from the bronze material, testing of phase composition and some parameters of the resulting coatings on steel products was carried out. Operating capacity of the proposed process reaches 7–15 kg/h for bronze powder when using a moderate power of the torch – up to 35–40 kW and a limited flow rate of hydrocarbon gas (for example, LPG of the SPBT grade) – 0.1–0.35 kg/h. Analysis of the energy efficiency parameters of the developed technology, as well as its calculated technical characteristics, in a comparison with plasma and combined equipment of a similar purpose, showed that it has an advantage in terms of target indicators, in particular, in terms of energy consumption and total energy efficiency of the spraying unit, not less than 20–30 %. This makes it to proceed later to the stage of application of this technology into production based on a new process for the metal coating formation, in particular with antimicrobial properties, with improved energy efficiency of the process.

To carry out a power calculation of the anti-driveaway device (AD) of lifting cranes operating in the open air, it is necessary to know the conditions that ensure their reliable stop and fixation on rails, as well as kinematic parameters, namely, the speed and acceleration of cranes when they move along the rails under the influence of  the wind force. The considered AD for stopping cranes driven away by the force of the wind uses a tong gripper driven by an eccentric mechanism.The paper presents the calculation of the forces arising during the operation of the tong gripper, considering the possibilities of various types of friction on the contact surfaces both in the absence of lubrication and in its presence.  The calculations of the eccentric mechanism as one of the fundamental mechanisms of the anti-driveaway crane device are presented in the paper. The stronger the wind force, the more due to the kinematic connection of the two mechanisms, when turning the eccentric mechanism, the pressure of the tong mechanism increases on the side faces of the head of the crane rail. The constructive solution of the AD excludes any actions of the personnel and makes it automatic.

Spatial cardan mechanisms designed to transmit rotational motion between shafts, having angular displacement, differ in a variety of design solutions. Cardan gears are an articulation of one or more universal joints and tubular shafts.  They compensate for axial movements, and also transmit torque at constant or variable angles between the connected units. During operation, the cardan transmission must function satisfactorily during the established service life, i. e., meet all the requirements arising from the peculiarities of its use. Therefore, the problem of improving cardan gears, increasing their reliability and ergonomicity on the basis of new design solutions optimized for dynamic parameters, materials used, manufacturing, assembly and operation technologies is relevant for modern technology. The paper presents a systematic approach to the creation of a new generation of cardan gears based on research in the field of operating conditions, materials science, materials technology, optimal design. It is shown that according to the results of the research, a new series of gimbal gears with improved technical characteristics has been created.

The paper considers contact problems for a stamp located at the end of an elastic half-strip without friction under the action of a concentrated force. A practical analogue of this problem is the support zone of a beam or truss on the head of a rectangular column, since the supporting parts of beams or columns have high bending rigidity. The calculation is performed in two stages. At the first stage, the variational-difference method solves the problem of the action of an arbitrarily applied concentrated force on the end of an elastic half-strip. The solution of this problem makes it possible to compose a square matrix of vertical displacements of the points of the end of the half-strip from the action of a single force. At the second stage, the Zhemochkin method solves the contact problem for a stamp arbitrarily located at the end of the elastic half-strip. The coefficients of the canonical equations of the forces method in the Zhemochkin method are based on the previously obtained matrix of vertical displacements of the end points of the elastic half-strip. Three problems for stamps located at the end of an elastic half-strip are considered in the paper. Graphs of the distribution of contact stresses, a plot of bending moments are given and the position of the force causing the translational movement of the stamp located on the edge of the half-strip is determined. The similarity of the obtained is noted with the results for a stamp located on an elastic half-plane.

The paper presents calculations of various design schemes for vibration isolation of a building with a reinforced concrete frame from a source of vibrodynamic exposure located outside it. It is noted that in most studies, the maximum value of the velocity of vertical vibrations of the foundation or soil in front of it is used as a criterion for the risk of damage to load-bearing building structures. The main factors that determine the risk of damage to structures are identified. These include the engineering and geological conditions of the soil at the base of the affected foundations, the degree of damage to the building, the type and design of the building or structure, the vibration frequency, the duration of the vibration, the distance to the vibration source, the type of vibration source, the material of the structure and the type of foundation. Based on the analysis of factors that determine the risk of damage to structures, the parameters of a building or structure that are least sensitive to vibrodynamic effects and have greater operational reliability are identified. It should be with a frame made of reinforced concrete or steel, not damaged, located on foundations of pile-racks in strong, low-moisture coarse sands or hard clays. The proposed design schemes for vibration isolation are mainly based on one of the vibration damping mechanisms in the soil medium – scattering on inhomogeneities. The finite element method has been used as the main tool for theoretical research. The ground medium has been considered as an elastic inertial array bounded by non-reflecting boundaries. The reliability of its application for calculating the development of dynamic processes in the system “oscillation source – propagation medium – oscillation receiver” has been confirmed by verification based on data from small-scale laboratory experiments. The use of the finite element method (FEM) makes it possible to take into account the spatial variability of soil conditions, the properties of materials, the design features of buildings and structures, the magnitude, direction and point of application of the dynamic load, as well as to model and optimize various vibration protection schemes. Seven variants of vibration isolation have been considered: the device of an inertial slab on the surface of the soil medium between the vibration source and the building, the installation of a vertical screen from gas-filled cylinders under pressure, a combination of these methods, the installation of a pile field in the soil medium, the reinforcement of the columnar slab foundations of the building with micropiles, the installation of a ribbed slab on the surface soil environment between the source and receiver of oscillations, the device of a reinforced concrete cage around the foundation-source of oscillations. The effectiveness of each method of vibration isolation has been evaluated by the damping coefficient K, a parameter showing how many times the speed of vertical oscillations of the building foundation decreases. Among the above methods of vibration isolation, two most effective options have been identified: in the form of a horizontal inertial slab of reinforced concrete on the surface of a soil mass (4.5-fold reduction in the rate  of vertical vibrations), and a vertical barrier made of pressurized gas-filled cylinders (reduction in the rate of vertical vibrations by 3.32 times).

The paper investigates the results of solving spatial contact problems on the free support of bending rods (hereinafter referred to as beams) on elastic quarter-space and octant of space. The objectives of the study include determining the stress state of contact pads, obtaining a picture of the distribution of contact stresses over them, and studying the features that arise when solving these contact problems. The main solution method is the method of B. N. Zhemochkin, based on the discretization of contact areas by replacing a continuous contact with a point one. This approach allows us to reduce the contact problem to the calculation of a statically indeterminate system using well-developed methods of structural mechanics. The mathematical model of the contact problems to be solved is built on the assumption of linear elastic (geometric and physical linearity) work of both the bending element and the elastic foundation. Since in the process of deformation the end sections of the beam element can break away from the support areas, the contact problems to be solved belong to the group of contact problems with a previously unknown contact area. The design schemes of such problems are constructively nonlinear, and their calculation is carried out by iterative methods. Based on the results of solving the considered contact problems, it has been found that with a geometrically symmetrical support of the beam element on the left and right on elastic quarter-spaces (space octants) with equal support areas, but different mechanical characteristics, as well as symmetrical loading, the values of support reactions, considering them as resultants of contact stresses on the left and right contact pads, and the coordinates of the points of their application are not equal to each other. The solution of the contact problem leads to a similar result in the case of a bending beam element resting on the elastic quarter-space on one side, and on the edge of the space octant on the other. In addition, a constant torque appears along the entire length of the beam element, indicating that the beam element is in a torsional transverse bending condition.

The paper presents the comparative characteristics of the most common modes of heat and moisture treatment (HMT), their advantages and disadvantages, as well as proposals for optimizing the HMT stages to obtain 

the maximum effect of accelerating concrete hardening through the use of thermal energy. Heat and moisture treatment of concrete is one of the most difficult stages in the technology of prefabricated and monolithic concrete. The basis for the durability of structures, their uninterrupted service during the design period of operation is a properly selected HMT mode, which improves the quality of products and reduces material costs in the form of a reduction in energy costs. Therefore, the still practiced simplified methods for selecting the HMT mode are unacceptable. Only under the condition of strict and scientifically substantiated consideration of a complex of factors influencing the ongoing processes of formation of the structure of cement stone and concrete, and the interaction between them, it is possible to obtain concrete with the required characteristics. Depending on the requirements for the finished material, based on knowledge of the mechanism of heat and mass transfer, rational methods and modes of heat treatment of concrete and reinforced concrete products can be calculated. A variety of HMT modes is due to the desire to reduce the possibility of defects in the concrete structure (for example, modes with a stepped or curvilinear temperature increase, which reduces the temperature gradient across the product section), to reduce energy costs (modes with the exclusion of the isothermal holding stage), etc. In the process of HMT of concrete and reinforced concrete products, a number of chemical and physical transformations of the concrete mixture (concrete) occur, as a result of which various defects in the structure of the material may appear, which worsen its properties (strength, permeability, shrinkage, creep and, in general, durability of concrete). Modern technology for the production of concrete and reinforced concrete products and structures provides for the introduction of various chemical additives,  their effect on the hardening of concrete at elevated temperatures, unfortunately, is not sufficiently reflected in the specialized literature. For example, the duration of the total cycle of concrete HMT when using chemical additives – hardening accelerators can be reduced by reducing the periods of preliminary exposure, temperature rise and the duration of isothermal exposure; and the use of plasticizers, depending on their type and content, can lead to a lengthening of the cycle. It is necessary to have analytical dependencies for calculating HMT modes and a computer model of the concrete hardening process at elevated temperatures.

A rectangular reinforced concrete slab is considered taking into account its physical nonlinearity on a linearly elastic homogeneous base under the action of a vertical external load. The anisotropy and heterogeneity of the slab are due to the properties of reinforced concrete, as well as the formation of cracks from the action of an arbitrary load during operation. The nonlinear problem was solved by the Zhemochkin method using the iterative algorithm of the Ilyushin elastic solution method. The Ritz method (determining the deflections of a slab with a pinched normal) and the Boussinesq solution (determining the displacements of points on the surface of an elastic half-space) were used to determine the coefficients of the resolving equations of the Zhemochkin method. At the first iteration, the slab was calculated as linearly elastic, 

orthotropic, and homogeneous; at subsequent iterations, it was calculated as linearly elastic, anisotropic, and inhomogeneous at each Zhemochkin site. The deflections of the middle surface of the slab from a unit force were determined as a series according to the first five particular Clebsch solutions. Experimental and numerical researches have been carried out. The latter – with the help of the MATHEMATICA computer program. The results obtained showed that the proposed calculation method allows one to accurately describe the distribution of settlements and reactive stresses under the slab. Verification of the methodology for static nonlinear calculation of a rectangular reinforced concrete slab, taking into account its physical nonlinearity, was carried out by comparing the results of calculations of maximum settlement and average pressures under the slab, obtained using the proposed methodology, and the results obtained using the layer-by-layer summation method and modern software systems Lira and PLAXIS 3D.

As it has been shown in part 1 of this paper, modern head lighting, due to  objective design flaws, does not always meet the requirements of existing international  standards, which means a decrease in road safety. To eliminate the previously Multibeam type.  These types of headlights  are currently either undergoing the stage of production tests or are used in extremely limited batches of vehicles in terms of the number of produced units. According with the results of this analysis, recommendations have been formulated for the design of advanced head lighting. The main of these recommendations is the use of single high-power LEDs with total internal reflection reflectors, which will provide a sharp cut-off border with efficient use of the source light flux. To increase the resistance of the headlight to temperature rise, it is proposed to use LEDs or other economical light sources together with phosphor parts. It is shown that adaptability is a useful but optional property of vehicle headlights, since it leads to complicate the design, and this is not always justified. The advantages of the headlight, created taking into account the above recommendations, are described, the main of which are the simplification of its design, reduction in weight and improvement of the thermal parameters of the product.