Technical Physics最新文献

A method is proposed for calculating an atmospheric plasma torch with gas stabilization. The calculation mainly uses criterion dependencies collected from known sources. These dependencies facilitate the determination of the primary characteristics of the plasma torch to be designed with a reasonable degree of accuracy and ease. A series of calculations determines the geometric dimensions of the plasma torch, working gas consumption, arc parameters (current and voltage), gas dynamic characteristics of the flow, electrode life, heat fluxes to structural elements, thermal stress of structural elements, and the energy (thermal) efficiency of the plasma torch. The cooling system of the plasma torch is calculated, and the costs required to cool its components are determined. The calculation results can be used to design a plasma torch.

We consider the regularities in critical phenomena including fracture of materials, crystallization, combustion, and explosion, as well as sintering of materials as a thermal process. Sintering is widely used for consolidation of particles in machine building articles in such as ceramics, metals, polymers, and cemented carbides. We outline the complex of problems that must be solved for fundamental and applied investigations of processes in the theory of classical phenomena and propose their physical analogs. We propose a model of the process as an important supplement to experiments, which is required for understanding sintering mechanisms as well as for optimization and designing of the process. Basic hypotheses and boundary conditions for the application of models are formulated. We consider the problems of the theory of the laminar–turbulent transition, which require detailed understanding of processes and quantitative models on different scales.

We propose a variant for calculating an atmospheric plasma torch with the gas stabilization and a fixed arc length. In the calculation, predominantly criterion dependences have been used. The proposed variant for calculating the plasma torch parameters is characterized by a more meticulous calculation of cooling of plasma torch components and a slightly modified algorithm for calculating basic parameters. The calculation technique makes it possible to determine the main structural dimensions of the plasma torch with a chosen structure and the main working parameters of the process occurring in it or perform the checking calculation of the plasma torch with known parameters. Based on the resulting sizes and characteristics of processes, more detailed calculations can be performed for separate elements of the structure or processes that are not included in the proposed methodology.

The article presents the results of a study on the efficiency of automation complex for manufacturing the “Body” (housing) parts using the investment casting method with the integration of the KUKA production system. A comparative analysis of options for organizing the technological process has been carried out (traditional with complex automation based on KUKA robots). The study is based on a systems approach, including mathematical and virtual modeling as well as experimental studies on pilot batches of parts. The results of the study demonstrate a significant increase in technological indicators with complex automation: manufacturing accuracy has been increased by 3.5 times, the level of defects has been lowered from 10.5% to 1.2%, and the duration of the production cycle has been reduced by more than 3 times.

A decomposition approach to mathematical modeling of nonlinear microwave devices with a distributed interaction has been developed based on descriptors of nonlinear autonomous blocks with Floquet channels (NABFs) in the form of nonlinear equations connecting the amplitudes of incident and reflected waves at the input cross section of Floquet channels. An iterative method for NABF decomposition has been developed based on the linearization of their descriptors. Using the computational algorithm developed by using the NABF method, the results of mathematical modeling of nonlinear diffraction and interaction of microwaves with nonlinear conducting and dielectric inclusions in striplines have been obtained.

The isobaric heat capacity of samples of industrial molybdenum-containing industrial water runoff formed in the course of epoxidation at the Public Joint Stock Company “Nizhnekamskneftekhim” (Niznnekamsk) is analyzed. The effect of emulsification on the properties of industrial water runoff samples is investigated. The regularities of the change in the drain structure depending on the dilution rate and the ultrasonic modes of ultrasonic action are established. It is shown that emulsification affects the heat capacity of weakly diluted wastewater insignificantly.

The effective scattering surface, i.e., the RCS parameter of the graphene nanoribbon array irradiated by a normally incident terahertz TEM-wave (p-polarization) with applying an perpendicular external magnetic field has been simulated using the CST MWS software package. A numerical investigation has been performed of the ratio of the amplitudes of the horizontal E_x and vertical E_y components of the scattered field at the points of the main lobe cross section of the scattering pattern in the absence and with an external magnetic field. It is shown that as a result of diffraction of a linearly polarized TEM-wave on the graphene nanoribbon array with applied magnetic field, the transmitted and reflected waves have an elliptical polarization (the polarization ellipse being strongly elongated), in contrast to the case of zero external magnetic field, when the transmitted and reflected waves have a linear polarization.

Using the MWS CST software, the diffraction of a TEM-wave (with the p-polarization) normally incident on the grating of graphene nanoribbons (GNRs) under applying a magnetic field in the direction perpendicular to the graphene plane is simulated. With the help of the MWS CST software, numerical analysis of the scattering pattern 3D e-Field in the far-field is performed for the vertical Е_y and horizontal Е_х components of the diffracted field for different values of magnetic induction B₀ at the magnetoplasmon resonance frequencies. The results of calculation of the ratio Е_х/Е_у of the horizontal and vertical components of the diffracted field are obtained at the points of cross section (φ = 0) of the main lobe of the 3D e-Field scattering pattern; it is shown that the variation of the horizontal component Е_х of the diffracted field as a function of magnetic induction B₀, which is due to the gyrotropy of the graphene conductivity and the magnetooptical effects emerging in this case, is demonstrated.

The emergence of jumpwise increases and decreases in the isobaric heat capacity of the ternary mixture of ethanol, rapeseed oil, and heterogeneous catalyst Al₂O₃, which are components for obtaining biodiesel fuel, is substantiated theoretically. Temperature ranges of melting, dissolution, and chemical reaction are revealed.