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The application of heuristic methods in the design of transmissions is investigated. The entire path that the designer passes from the development of the design requirements, then the preliminary design and finally the development of the detailed design is considered. Heuristic methods are divided into three groups according to three design phases. For each phase, one generalized heuristic method that includes all heuristic techniques of the known methods referred to a particular group should be used when designing transmissions. Special attention is paid to the methods that use matrix and graph models. These methods are the most suitable for analyzing complex technical objects. Search for design features that are not used in right-angle gearboxes is performed by the method of creativity enhancement. Using the method of studying the structure of the problem based on the use of matrix and graph models at the phase of preliminary design, it was found that the power split in the bevel stage is possible at an angle between the axes of the bevel gear not equal to 90°. A comparative analysis of the found design with the existing gearbox at the phase of detailed design using the method of evaluating the variants for a design solution is made. Evidence of the effectiveness of heuristic methods is the development of a new gearbox design with better technical characteristics: smaller weight and dimensions. The developed heuristic methods are aimed at solving the tasks of designing transmissions; they can be used by designers, inventors and are interesting for experts in the field of heuristics.

references svetlana Podnebennaya State Higher Educational Institution «Priazovskiy State
Technical University» orciD: http://orcid.org/0000-0002-0878-1492 irina zakharova State Higher Educational Institution «Priazovskiy State Technical University», Mariupol, Ukraine orciD: http://orcid.org/0000-0002-3492-0134 New topologies of single-phase inverter welding supplies with increased power factor are proposed. The need to increase the power factor of welding equipment is dictated by the introduction of modern standards of electromagnetic compatibility of technical equipment. One of the proposed power supplies is built on the basis of a modified forward-current converter, the other is based on a bridge converter. A distinctive feature of the presented power supplies with an increased power factor is the absence of additional inductive power components, a smaller capacity of the smoothing capacitor and a simplified scheme of limiting its charging current. The developed welding power supplies have an increased no-load voltage, which makes it possible to lightly ignite the arc during manual arc welding. Due to the increased power factor, the current consumed from the mains is 30 to 45 % lower than for widely used welding inverters without power factor correction. The presented circuit solutions of the converters allow creating welding inverter power supplies with a high-power factor, having a lower cost and better weight and size characteristics in comparison with professional welding inverters equipped with power factor correctors.
keywords: power factor, welding inverter, welding source, ignition of arc, stabilization of arc burning. Torque flow pumps (TFP) exhibit low indicators of energy efficiency. This is related to the features in the operating process of their flowing part. Given this, improvement of elements of the flowing part of TFP looks promising in terms of increasing their energy efficiency. Taking into account the structure of the pump life cycle cost, the most rational is the improvement of the impeller design without changing its overall dimensions. This will make it possible to increase the TFP efficiency with minimal investment cost.
The study was conducted using the method of experiment planning. This allowed us to rapidly and accurately determine the extent of impact of the selected factors on the pump operating parameters.
As a result of numerical investigation, we established the effect of the examined structural elements of the impeller on the pump parameters. A change in the design of the blade enabled a reduction of hydraulic losses in the inter-vane channels of the impeller. Alignment of the blade installation angle with the angle of a fluid inleakage decreased the resistance of input edge of the pump blade. As a result, hydraulic losses at the input of the impeller were reduced.
The study conducted allowed us to improve efficiency of the torque flow pump by 4-5 %. Adequacy of the results of numerical investigation was confirmed by performing a physical experiment.
keywords: torque flow pump, Turo, impeller, numerical investigation, Ansys CFX, factorial experiment. We determined that viscous flow processes are influenced by composite materials of ethylene-vinyl acetate copolymer that do not sustain combustion and by flame retardant fillers. In the study, ethylene-vinyl acetate copolymer was used. The content of vinyl acetate is 18 % and 28 %; MFI is 2.5 g/10 min or 5 g/10 min. Flame retardant fillers include aluminum oxide trihydrates with an average diameter of particles of 1.5 μm and 3.0 μm; magnesium oxide dihydrates with an average diameter of particles of 3.0 μm and 3.7 μm and hydromagnesite with an average diameter of particles of 1.4 μm.
By using the method of capillary viscosimetry, we defined the following characteristics: melt flow index, shear stress, shear rate, effective viscosity and activation energy of viscous flow. Melt flow index decreases as the concentration of flame retardant fillers increases. The same tendency is observed when using flame retardant fillers with smaller average diameter of particles. Shear stress and effective viscosity, in contrast, increase.
We determined the influence of polymeric matrix, composition and dispersion of flame retardant fillers on the rheological characteristics of polymeric compositions. The use of EVA with melt flow index of 5 g/10 min makes it possible to obtain the filled polymeric compositions with improved rheological properties.
The obtained results might be useful in the process of designing the formulations for polymeric compositions for cable products and for regulating technological indicators during their processing.
keywords: composite materials, fire resistance, ethy lenevinyl acetate copolymer, flame-retardant fillers, rheological properties. Optimization and control of technological parameters in the machining of composite materials is an important task to ensure quality of the manufactured products. Studies are undertaken to solve the given problem using the method of acoustic emission. We considered procedure and results of experimental research into parameters of acoustic emission signals when changing the depth of composite machining. It was determined that increasing the depth of composite material machining did not not affect the character of acoustic radiation. Acoustic emission is continuous. However, there occurs an increase in the mean level of amplitude of the registered emission signal and the magnitude of its variability. We determined statistical amplitude parameters of acoustic emission signals at increasing the depth of composite machining. The data approximation was performed and the mathematical notation derived of the regularities at an increase in the mean level of amplitude, its standard deviation and variance with increasing machining depth. It was established that regularities of the increase in the amplitude parameters of acoustic emission signals were well described by nonlinear functions. It was determined that the most sensitive and informative parameter of the registered acoustic emission signals was a variance in the mean level of amplitudes.
It is shown that the percentage increase in the variance of the mean level of signal amplitude outpaces the percentage increase in the mean level of amplitude and its standard deviation. The obtained patterns could be used for the optimization of technological processes. When conducting machining -to monitor, control and manage the depth of machining a composite with the assigned structure.
keywords: acoustic emission, composite material, signal amplitude, machining, statistical characteristics, cutting depth. The process of formation of the upper part of a raw cotton bundle was examined. We proposed a method for kinematic analysis of mechanisms of the cotton-processing machines, including a mechanical bundling press, and developed an algorithm for its computer implementation. The proposed method makes it possible to obtain equations for determining the kinematic parameters of a mechanism for the formation of the upper part of a cotton bundle at the assigned law of the motion of a drive link, which is the cam. We experimentally studied the possibility of forming the upper part of a bundle with the required density of cotton, which ensures stability of the formed bundle. Taking into account the influence of density of raw cotton in the bundle on the adhesion between waste and cotton, and based on the impact of this on the cleaning effect, we conducted theoretical and experimental research. The study performed allowed us to determine the density of raw cotton in a bundle depending on the time and height of the bundle, and to investigate the influence of waste adhesion on the ginning effect.
keywords: raw cotton, cotton bundle, bundle shape, upper part of a bundle, cam, bundle density, grate, ginning effect, adhesion.