The paper considers the important issue of change in the pressure drop when the seal wears out. An engineering calculation method was developed that allows one to determine how the pressure drop across seals will change during their stepwise wear, depending on the cylinder diameter and pressure ratio. The equivalent clearance of a worn seal was determined experimentally to be 6, 9, and 14 µm for cylinder diameters of 20, 50, and 80 mm, respectively. Based on the results of the numerical experiment, the dependences of the pressure drop on the seals were obtained depending on the number of worn seals and the pressure ratio in the cylinder.
Previously developed combined methods of stray light compensation for time cameras of time-of-flight systems have demonstrated high efficiency in laboratory conditions, but their operation in real livestock buildings faces additional destabilizing factors: rapid changes in illumination (movement of the Sun, switching on/off LED lamps), dustiness of protective optics, and dynamic shadows from animals and personnel, as well as the movement of objects (animals). This paper presents the results of long-term field trials on a dairy farm (120 heads). A unique dataset (ToF + RGB + reference laser scanner) was collected in 12 different lighting scenarios. Based on this data, a physics-informed neural network (PINN) is a deep-learning neural network that takes raw intensity and phase data (224 × 171 pixels) as input and directly reconstructs depth without iteratively solving the inverse problem. The network uses regularization based on the diffusion approximation and the wet film model. After optimization on a Raspberry Pi 5 single-board computer, the processing time of one frame was 8.2 ms (120 fps), which is ten times faster than the previous algorithmic solution. Moreover, the root-mean-square depth error on moving animals is reduced by 72
A technique for the electrodynamic calculation of the effective permeability tensor of 3D magnetic nanocomposites in a model of a nanostructured gyromagnetic medium as a quasi-continuum one has been developed on the basis of solving a quasi-compatible system of equations. Based on the solution of Maxwell’s equations together with the Landau‒Lifshitz equation of motion of the magnetization vector in a ferromagnet, the electrodynamic calculation of components of the effective permeability tensor of a 3D magnetic nanocomposite based on an opal matrix depending on the relative value of the magnetization field has been carried out taking into account the exchange interaction and in the non-exchange approximation.
In this paper, we propose a cathode groove etching structure in which the surface concentration of the p2 region can be increased to the surface concentration of the cathode region in order to enhance the cathode shorts effect of SCR with Ni electrode, and analyze the relationship between the dV/dt capability and cathode groove etching structure parameters of the device. Unlike the Al electrode structure, the limitation of surface concentration of the cathode region in the Ni-electrode SCR is that the surface concentration of the shunt contact cannot be as high as that of the cathode region, and the failure of the shunt contact surface to be an ideal ohmic contact is achieved by cathode groove etching. In a thyristor with Ni electrode, cathode groove etching is used to increase the surface concentration of the p2 region from 1018 to 1020 cm–3.
A unique design for a reciprocating compressor with a flexible piston is proposed and examined, in which the end surface is made of an elastomeric element and capable of deflecting inward. This design, along with eliminating the linear dead volume, further increases the efficiency by means of the volume created by the deformed elastomeric element. The model for calculating the piston compressor’s working process is refined taking into account an increase in the working chamber volume. With the assumed maximum deflection of the elastomeric element (20
The important topic of autonomous operation of a compressor machine is considered. It has been shown that at present, there is not a single branch of the national economy in which compressor machines are not used to one degree or another. It has been shown that cylinder–piston seals are the node that fails most frequently. The goal is to achieve a service life of 60 000 h, which is achieved by installing additional seals on the piston. It shows how many seals need to be installed on a piston to achieve a service life of 60 000 h, depending on the material used, the cylinder diameter, and the pressure ratio in the cylinder.
A mathematical model of the problem of a cylindrical body flow by a supersonic gas flow in the boundary-layer area is considered. Classical difference schemes do not accurately describe the boundary differential problem due to the fact that its solutions allow for areas of large gradients. In this regard, a higher-order difference scheme was constructed and justified on a three-point pattern, which provides an adequate account of the approximation viscosity commensurable with the value of the grid step. A numerical experiment was performed, which allowed the effectiveness of the higher-order scheme to be evaluated.
A method for calculating the radiation characteristics of ozone under conditions of vibrational–rotational nonequilibrium is proposed for use in remote monitoring of the Earth’s atmosphere using aviation systems. The method is based on the use of the classical narrow-band k-distribution model, which includes corrections for disequilibrium. These corrections include vibrational and rotational distribution functions, as well as averaged Boltzmann functions over vibrational and rotational temperatures. To check the method, a series of nonequilibrium calculations were carried out, which were compared with the exact line-by-line method in the spectral range of 500 to 1150 cm–1. The comparison, which was carried out over a wide range of pressures, translational, rotational, and vibrational temperatures, showed good agreement.
The relevance of the study is determined by the fact that in the presence of single and three phase loads, the network mode is almost always asymmetric, which causes additional losses of electricity. The aim of the study is to evaluate methods and develop algorithms for calculating electricity losses from consumers in 0.4 kV networks with single and three phase loads using measurement systems. The tasks of study are analyzing of the graph resulting from daily monitoring of loads by a device for measuring power quality indicators (RESURS UF); determining the coefficient of additional losses that arise when the loads are unbalanced; defining an algorithm of procedures and calculations to reduce electricity losses resulting from unbalanced loads and determining the losses for a 0.4 kV overhead line of standard length 600 m and 15 towers using method of loop currents. The results of the study are the need to monitor loads using smart meters to calculate electricity losses and determine the optimal load balance; an algorithm was developed to reduce electricity losses by balancing loads, which can be generalized to all power supply organizations and analysis of methods for calculating modes of four lines network with a load distributed along the line showed the rationality of using the method of loop currents.
The paper investigates the process of introducing visible and near-infrared optical radiation into a multimode optical fiber through a macrobending region. It has been established that the input coefficient depends significantly on the radiation wavelength, the macrobending radius, and the number of fiber turns. It is shown that decreasing the macrobending radius and increasing the number of turns leads to an increase in the efficiency of radiation input, with the greatest losses observed in the shortwave region of the spectrum. The obtained results allow us to gain a deeper understanding of the mechanism of radiation input through macrobending and can be used in the development of fiber-optic light sensors and other optical devices.
In the paper, the results of a study of collisions between small-sized models and large single droplets have been presented. Methodological experiments have demonstrated the viability of a ballistic stand and developed methods for synchronizing the model’s flight through the measurement section and its photographic recording. Initial data on the characteristics of asymmetric and quasi-symmetric interactions between the model and a single large droplet have been obtained. Several objectives for further research have been formulated.
The article presents the results of a study of changes in the operational properties of AERO 2T and M-5z/20 AERO engine oils under thermal oxidation conditions at temperatures of 150–200°C, simulating the operation of an aircraft rotary piston engine. The effect of topping up fresh oil (up to 20
The development of digital technologies that improve diagnostics and increase the reliability of determining the functional characteristics of agricultural machinery in real time is important and relevant for the technical support of high-power machines. To develop an intelligent system for remote diagnostics of engines of high-power agricultural machinery, a neural network constructor with the ability to use up to ten input and output parameters has been used. An algorithm for a digital remote diagnostics system, a failure prediction model for online monitoring, and a digital platform for diagnosing high-power agricultural machinery have been developed. The developed platform has enabled the acquisition of diagnostic parameters of the internal combustion engine (fuel consumption, engine temperature, and engine speed). These parameters are remotely transmitted as encrypted data to a server via a GPS modem and digitized in a database, where the data is structured and analyzed using a developed artificial neural network model. The decrypted engine diagnostic parameters are sent to the operator, who views graphs of agricultural machinery technical condition parameters and reports on predicting possible internal combustion engine component failures. A method for collecting and storing diagnostic information obtained from monitoring the technical condition of agricultural machinery has been presented, and these data have been processed using a mathematical neural network model. The use of digital technologies in diagnosing equipment using artificial intelligence makes it possible to reduce significantly the labor intensity of operations, evaluate overall machine performance, predict failures, conduct timely maintenance and repairs, and reduce unplanned downtime of energy-intensive agricultural machinery.
The effect of the plasma modification on dyeing of textile materials made from two-component yarns with disperse dyes has been studied. The experimental data confirming the increased efficiency and quality of dyeing after the plasma processing of microfibers are reported. Changes in color fastness to dry and wet rubbing, as well as the fastness after multiple washings, have been examined. It is shown that the plasma processing makes it possible to reduce the amount of dye used while maintaining the high dye quality.
The aim of the work is to evaluate the influence of the concentration of a liquid glass solution (Na2O·nSiO2) on the parameters of plasma-electrolyte spraying and the morphology of hollow SiO2 microspheres. Solutions with SiO2 concentration of 0.1, 0.5, 1.0, and 1.5 mol/L were used simultaneously as an electrolyte and a source of silica. The synthesis was carried out at atmospheric pressure in a tip-ring cell at a constant voltage of 400 V for 10 min, followed by washing and drying of the precipitate. The morphology was analyzed using scanning electron microscopy; size statistics were determined for at least 200 particles for each mode, and wall thickness was determined for 30–50 shell fractures. It has been shown that increasing the concentration leads to an increase in the average particle diameter from 4.5 ± 1.8 to 7.0 ± 2.0 μm and a thickening of the shell from 50 ± 10 to 180 ± 30 nm. The proportion of destroyed shells has a minimum in the range of 0.5–1.0 mol/L (15 ± 4 and 10 ± 3
The effect of combined plasma processing of rabbit skin leather and ethylenediamine-based urethane glycol at the tanning and dyeing stages has been studied. The plasma processing modifies the microstructure of a porous capillary material and increases the collagen reactivity, thereby intensifying the subsequent dyeing of the semi-finished fur product.
The study examined the influence of bore gauge measurement errors on the formation of the number of incorrectly accepted and incorrectly rejected bushing holes under the camshaft journals cylinder blocks of YaMZ engines. The rationality of using the most accurate bore gauge from a range of universal instruments that satisfy the basic conditions for selecting measuring instruments has been scientifically substantiated and practically proven; otherwise, even if the selection condition is met, the percentage of losses increases in the form of sending such expensive parts as cylinder blocks to scrap.
The TACTIC (TeV Atmospheric Cherenkov Telescope with Imaging Camera) is a 4 m imaging atmospheric Cherenkov telescope designed for very high-energy (VHE) gamma-ray observations and has been operational at Mount Abu, India, for over two decades. The telescope’s light collector has recently been upgraded to a tessellated structure comprising 34 spherical mirrors fabricated from single-point diamond-turned aluminum alloy (Al 6061-T6). Each mirror has a diameter of 600 mm and a focal length of 4000 mm. Previously, the telescope employed glass mirrors of the same diameter, which required frequent aluminization due to degradation of reflectivity under prolonged atmospheric exposure. In this work, we present qualification studies of the diamond-turned metallic mirrors to evaluate their optical performance and environmental durability for Cherenkov light collection in the 300–700 nm wavelength range. The characterization includes spot size measurements using the 2f method, surface roughness evaluation, reflectivity assessment, and water ingress testing. Additionally, ray-tracing simulations were performed using ROBAST to estimate the point-spread function (PSF) for all 34 mirrors of the TACTIC telescope. The results demonstrate that the developed mirrors satisfy the required specifications and are suitable for long-term operation under site-specific environmental conditions.
The procedure and sequence of quality assessment of processes of controlling carried out during machine repair are considered. The quality of the process of controlling the intermediate shaft diameter of a ZMZ engine using a caliper gauge was assessed. As a result of mathematical processing of the data, it was revealed that the process of control with a caliper gauge can be considered acceptable. Replacing the micrometer with a caliper gauge will not only improve the accuracy of control, but also significantly reduce the labor intensity of the work, which will ensure the quality of the assembly of the connection of the front journal of the ZMZ engine intermediate shaft with the bushing.
A single-stage plasma-electrolyte method for the synthesis of hollow particles of silicon dioxide (SiO2) from an aqueous solution of liquid glass without the use of solid templates. A contact glow discharge in the electrolyte was maintained by a dc source with smooth regulation of the output voltage in the range of 0–400 V and a current of 0–10 A in an alkaline solution of Na2SiO3 (≈5 g/L SiO2, pH ≈ 12). The morphology of the obtained particles was studied using scanning electron microscopy (SEM). It was found that the main product is hollow spherical particles with a diameter of 0.5–2 µm (D50 ≈ 1.1 µm). Based on SEM images of the destroyed spheres, the shell thickness was estimated to be about 50–120 nm, which corresponds to a relative thickness of t/D ≈ 0.05–0.10. The mechanism of formation of hollow spheres and possible areas of application of the obtained microspheres as lightweight fillers and platforms for subsequent functionalization are discussed.
