Technical Physics最新文献

{"title":"Dynamics and Structure of Periodic Flows: Ligaments, Gravity and Acoustic Waves","authors":"Yu. D. Chashechkin, A. A. Ochirov","doi":"10.1134/s1063784224700506","DOIUrl":"https://doi.org/10.1134/s1063784224700506","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The structural components of periodic flows of 2D and 3D viscous incompressible and slightly compressible fluids are classified. The classification is based on the properties of complete solutions to a linearized system, which have been constructed by the methods of the singular perturbation theory. The regular parts of the resulting complete solutions describe waves and singular ones—ligaments (fine components forming the structure of the flows). Dispersion relations have been obtained for different types of periodic flows, which describe proper (surface or internal gravity and acoustic) waves as well as accompanying ligaments. The problems of measuring the dynamics and structure of flows in laboratory and natural conditions are considered. The effect of ligaments on the results of measurements of physical quantities in the fluid flows are estimated.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142216384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two Iterative Methods for Solving a Volumetric Singular Equation for a Nonlinear Diffraction Problem in a Semi-infinite Rectangular Waveguide","authors":"A. O. Lapich, M. Yu. Medvedik","doi":"10.1134/s1063784224700622","DOIUrl":"https://doi.org/10.1134/s1063784224700622","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The goal of this study is to construct a nonlinear electromagnetic field inside a waveguide. We assume that a body is located in a semi-infinite rectangular waveguide and that an electromagnetic field propagates inside the body. Iterative algorithms based on solving a volumetric nonlinear singular integral equation are proposed and described. Numerical results are presented. The boundary value problem for the system of Maxwell’s equations is reduced to a volumetric singular integral equation. An iterative method for creating a nonlinear medium inside the body with a dielectric structure is constructed. The problem is solved numerically. The size of the matrix obtained in the calculation is about 15 000 elements. The internal convergence of the iterative methods are demonstrated. The curves illustrating the field distribution inside the nonlinear body are plotted. A numerical method for finding wavenumbers that make it possible to create a nonlinear field is proposed and implemented.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142216437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of Fundamentals of Calculation and Measuring Techniques in Fluid Dynamics","authors":"Yu. D. Chashechkin","doi":"10.1134/s1063784224700518","DOIUrl":"https://doi.org/10.1134/s1063784224700518","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The logics of contemporary scientific researches includes the requirement of formulation for distinctive determining the branch of science, the physical medium, and methods for solving problems. Flows are studied in two scientific disciplines, vis., engineering mathematics and technical physics. A flowing medium is characterized by equations of state for the Gibbs potential, density, and velocity of sound, as well as kinetic and other physical coefficients. Fluid flows are treated as transport of momentum, energy, and mass, which causes self-consistent changes in other physical quantities. Flows are described by the unified system of fundamental equations for all media (differential form of conservation laws). Calculations are performed in the algebra of complex numbers, where frequency is assumed to be real-valued, while wavenumber is complex-valued. Natural stratifications of the atmosphere and ocean are characterized by the buoyancy parameters. The classification of flow components is based on complete solutions to linearized and weakly nonlinear forms of fundamental equations, which are obtained by the methods of the singular perturbation theory. Regular components of solutions describe flows and waves on the surface of in the bulk of a fluid, while singular solutions describe the fine structure of the medium. In experiments performed on the stands of the Unique Hydrophysical Complex of the Ishlinsky Institute for Problems in Mechanics, Russian Academy of Sciences, upstream perturbations, internal wave fields, wakes with submerged and suspended vortices structured by interfaces and fibers during the motion of a plate, cylinder, and sphere in stratified and homogeneous fluids are singled out. Numerical calculations of a flow past a plate in a wide range of Reynolds numbers, including creeping flows with Re ~ 1 and nonstationary vortex regimes with Re ~ 100 000, are in qualitative agreement with the observations of schlieren patterns of flows in a stratified aqueous medium in the laboratory basin and in wind tunnels. The conditions for the extension of results to flows in natural conditions and problems in metrology in flight regimes are considered shortly.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142216382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computational Modeling of Transformations of Epidemic Waves of BA.2.86/JN.1 SAR-COV-2 Coronavirus Variants on the Basis of Hybrid Oscillators","authors":"A. Yu. Perevaryukha","doi":"10.1134/s1063784224700580","DOIUrl":"https://doi.org/10.1134/s1063784224700580","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract—</h3><p>We are developing a modeling method for oscillating processes in biophysics with discontinuous nonlinearities on the basis of logic of impulse perturbations and equations with a deviating argument. We compared specific variants of development of the epidemic situation in different countries due to regularly updated SAR-CoV-2 strains and discuss methods for modeling specific scenarios for the spread of this infection. The relevance of the development of modeling methods is due to the renewed waves of growth in COVID-19 cases in different regions in 2024 as an unusual variant of a pulsating epidemic process. The next surges of infections in New Zealand are determined by the long hidden presence of strains of the evolutionary leader branch BA.2.86/JN, which managed to split, which surpassed in their binding affinity to cells all the previously dominant Omicron sublines (B.1.1.529, XBB.2.3), and now JN.1 effectively evades vaccine antibodies. Earlier in 2023, XBB strains retained sufficient infectivity with reduced affinity for the ACE2 receptor and a lower replication rate compared to Gamma, but the persistence time of the virus increased. Due to immunization of the population, the trend of virus evolution has changed with an emphasis on the complication of the phylogenetic tree and with the selection of Spike protein variants that provide balanced characteristics for replication and evasion of antibodies. The variability potential in coronavirus proteins is high. Our method for predicting its prospecting mutations in a computational study of epidemic scenarios is necessary for species modified by expanding the set of statuses of individuals in compartmental models. Variants of systems of equations based on SIRS did not describe the resumption of COVID waves in Iran in 2020. Schemes for status transitions are not suitable in fundamental aspects for describing nonlinear oscillatory modes of the epidemic even after including second-order oscillatory equations in the linear SIR scheme. The equations with delay and with threshold effects during bifurcations of cycle generation, developed by the author for decaying COVID waves, take into account that new Omicron lines change the fluctuation modes. The real changes that we revealed in oscillation modes with an increase in repeated cases cannot be described only by restructuring the parameters of the equations with attenuation functions. According to the hospitalization graphs shown to us, in Finland, Wales, and Nepal, it is necessary to restructure the attenuation functions of the COVID waves. We described the aspects of the transitional phases of the modern COVID epidemic using special computational tools based on the nature of their nonlinear oscillations. Our original method for forming a structure for a hybrid model was substantiated on the basis of the choice from a set of right-hand sides of differential equations with heterogeneous delayed contr","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141611958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Features of Numerical Solution of the Maxwell Equations by the FDTD Method in the Homogeneous and Inhomogeneous Formulations","authors":"P. A. Makarov, V. A. Ustyugov","doi":"10.1134/s1063784224700543","DOIUrl":"https://doi.org/10.1134/s1063784224700543","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>We investigate the features of the numerical FDTD solution of the Maxwell equations, formulated as the Cauchy problems for the corresponding homogeneous and inhomogeneous systems of equations. It is shown that for the case of time-limited field sources, the Cauchy problem for an inhomogeneous system is equivalent to the corresponding Cauchy problem for a homogeneous system. The criterion for estimating the correctness of the obtained solution is formulated. The features of the numerical solution of the homogeneous and inhomogeneous Cauchy problems for different forms of initial configurations of electromagnetic fields and setting pulses are analyzed. The necessary and sufficient conditions for correctness of the obtained solutions are formulated.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetoelastic Measurement of Vibration of Downhole Tools","authors":"G. N. Akhobadze","doi":"10.1134/s106378422470052x","DOIUrl":"https://doi.org/10.1134/s106378422470052x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A principle for measurement of the vibration force of a downhole tool based on the use of magnetoelastic characteristics of ferromagnetic materials is proposed. The features of the construction of sensitive elements in the form of inductive and mutually inductive converters of a desired physical parameter are presented. The errors are estimated with respect to optimal cable transmission of information signal. An ultrahigh-frequency approach for calculation of the vibrational force based on varactor frequency tuning is proposed. Aiming at an increase in the efficiency of the measurement of vibration force, several widespread bridge measuring circuits are analyzed with a choice depending on the requirements for measurement accuracy and range of the desired parameter.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Specificities of Throwing the Shell of a Cylindrical Cumulative Charge to the Axis","authors":"E. Yu. Potanina, A. V. Guskov","doi":"10.1134/s1063784224700610","DOIUrl":"https://doi.org/10.1134/s1063784224700610","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A cylindrical shaped charge is a hollow cylindrical liner surrounded by explosive material. Jet formation in cylindrical cumulation is difficult to achieve, but is of interest to researchers due to its features: the high speed of the cumulative jet and the low gradient of jet speeds along the length relative to classical cumulation. To achieve stable jet formation, a two-stage cylindrical charge device has been proposed. The principle of its operation is based on the creation of an overcompressed detonation regime in the internal charge of the explosive. Thus, the speed of throwing the inner shell towards the axis will increase, which will lead to an increase in the angle of collapse of the shell and improved jet formation. A mathematical model of the functioning of such a device is presented, and several options for such shaped charges are considered. From a mathematical point of view, the possibility of functioning of such a device in the overcompressed detonation regime has been proven.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beamforming of Electrically Tunable Plasmonic Graphene Strip Nanoantennas in the Terahertz, Far-Infrared, and Mid-Infrared Ranges","authors":"G. S. Makeeva","doi":"10.1134/s1063784224700609","DOIUrl":"https://doi.org/10.1134/s1063784224700609","url":null,"abstract":"<p><b>Abstract</b>—The purpose of this work is to study, using automated modeling methods, the possibility of scanning in frequency and beamforming of plasmonic graphene strip nanoantennas, which are electrically tunable by varying the chemical potential of graphene in the terahertz (THz), far-, and mid-infrared (IR) ranges. Graphene, which has exceptional electromagnetic, mechanical, electrical, and thermal properties, is promising for reconfigurable THz antennas due to its high conductivity and tunability in the THz range. Modeling of the performances of THz plasmonic graphene strip nanoantennas for various values of chemical potential was carried out using the CST Microwave Studio 2023 software package. The results of modeling the controllability of the reflection coefficients at the input of the nanoantenna and the radiation pattern (RP) at the resonance frequencies of the fundamental mode of surface plasmon-polaritons (SPPs) and the second-order SPP mode were obtained when changing the values of the chemical potential (0.3–0.7 eV) in the THz, far-, mid-IR ranges. It follows from the modeling results that it is possible to tune operating frequencies (frequency scanning) from THz to the far- and mid-IR ranges and form a multibeam RP of reconfigurable graphene strip nanoantennas by changing the chemical potential of graphene (applying an external electric field) without changing their geometry and dimensions.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mathematical Model and Computational Algorithm for Calculating the Effective Electromagnetic Parameters of a Magnetic Nanocomposite","authors":"G. S. Makeeva","doi":"10.1134/s1063784224700592","DOIUrl":"https://doi.org/10.1134/s1063784224700592","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Mathematical models (taking into account the exchange and the boundary conditions) and a computational algorithm for calculating the components of the effective permeability tensor and the effective permittivity of magnetic nanocomposites have been constructed. The results of calculating the effective permeability tensor for a magnetic nanocomposite based on an opal matrix using a model that takes into account the exchange and magnetic-dipole interactions between magnetic nanoparticles are presented.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Building a Model of the Physical Principle of Operation of an Autonomous Locomotive with a Steam Power Unit","authors":"S. G. Postupaeva, A. A. Yakovlev, N. V. Fedorova","doi":"10.1134/s1063784224700531","DOIUrl":"https://doi.org/10.1134/s1063784224700531","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The article discusses the use of the engineering-physical method of exploratory design of an autonomous locomotive with a steam power unit at the stage of constructing a model of the physical principle of operation. The resulting model of the device allows one to display the movement of the working fluid in space and its physical interaction in time.</p>","PeriodicalId":783,"journal":{"name":"Technical Physics","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141611984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}