{"title":"Relationship between Theory of Incompressible Disperse Systems and Theory of Fluidization","authors":"Ya. D. Yankov","doi":"10.3103/S0027133021050058","DOIUrl":"10.3103/S0027133021050058","url":null,"abstract":"<p>This work proposes a mathematical model of dispersed systems with constant number densities of the dispersed and carrier phases (incompressible dispersed system). This model makes it possible to construct a physically meaningful and mathematically correct theory of the movement of bubbles in a boiling (fluidized) layer.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 5","pages":"130 - 135"},"PeriodicalIF":0.3,"publicationDate":"2022-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4753937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the Influence of Surface Forces on Diffusion in Solution at the Initial Section of Liquid Film Development","authors":"A. N. Beloglazkin, V. Ya. Shkadov","doi":"10.3103/S0027133021040038","DOIUrl":"10.3103/S0027133021040038","url":null,"abstract":"<p>The flow of a film of a viscous liquid is considered. The liquid is a weak solution containing a gas phase and a volatile surfactant. The distribution of the latter in the layer is controlled by the diffusion in the liquid volume, the adsorption–desorption processes between the liquid volume and the adsorbed near-surface layer, and the evaporation from the surface into the boundary gaseous medium. The process of the gas phase penetration from the external gas flow is specified by the diffusion inside the film.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 4","pages":"118 - 121"},"PeriodicalIF":0.3,"publicationDate":"2021-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4100142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. V. Aleksandrov, T. B. Aleksandrova, L. L. Cruzado, R. J. A. Escamilla
{"title":"Controlled Transition in a Model of Biomass Dynamics of Root Hemiparasitic Plants","authors":"V. V. Aleksandrov, T. B. Aleksandrova, L. L. Cruzado, R. J. A. Escamilla","doi":"10.3103/S0027133021040026","DOIUrl":"10.3103/S0027133021040026","url":null,"abstract":"<p>The article shows the possibility of solving the problem of the transition between periodic and point attractors in the bistable Rosenzweig–MacArthur model with modifications for the dynamics of root hemiparasitic plants and their hosts.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 4","pages":"111 - 117"},"PeriodicalIF":0.3,"publicationDate":"2021-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4099806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On Short-Wave Instability of One-Dimensional Radiative-Convective Models of Atmosphere in Quasi-Hydrostatic Approximation","authors":"X. Xu","doi":"10.3103/S002713302104004X","DOIUrl":"10.3103/S002713302104004X","url":null,"abstract":"<p>One-dimensional radiative-convective models are widely used for studying long-term climate and the influence of various processes (condensation of water vapor, motion of droplets, and their impacts on radiative fluxes, etc.) on the hydrodynamics of the atmosphere. However, long-term prediction of climate is difficult due to the properties of the systems of equations, i.e., a small short-wave perturbation of the basic solution leads to a local sharp increase in the amplitude of perturbation. In this work, a one-dimensional nonstationary model with quasi-hydrostatic approximation is established and the short-wave instability is analyzed for various approximate models with the quasi-hydrostatic approximation.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 4","pages":"105 - 110"},"PeriodicalIF":0.3,"publicationDate":"2021-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4099805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Bulgakov Problem for a Hyperbolic Equation and Robust Stability","authors":"V. N. Zhermolenko, R. Temoltzi-Ávila","doi":"10.3103/S0027133021040051","DOIUrl":"10.3103/S0027133021040051","url":null,"abstract":"<p>An inhomogeneous wave equation with dissipation in the presence of an external uncertain perturbation is considered. The problem of finding solutions with the maximum possible amplitudes is investigated. A method for solving this problem based on the Fourier method of separating variables and the Bulgakov problem of the maximum deviation of solutions of second-order ordinary differential equations with external uncertain perturbations is proposed. The application of the Fourier method is justified. The robust stability property of the considered wave equation is investigated.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 4","pages":"95 - 104"},"PeriodicalIF":0.3,"publicationDate":"2021-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4100134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Resonance in Multicomponent Linear Systems","authors":"A. A. Lykov, V. A. Malyshev, M. V. Melikian","doi":"10.3103/S0027133021030043","DOIUrl":"10.3103/S0027133021030043","url":null,"abstract":"<p>We consider a system of many point particles with arbitrary quadratic interaction and a harmonic force acting on a single fixed particle. Necessary and sufficient conditions for resonance and uniform boundedness of trajectories are obtained; and for the case of resonance the late time asymptotics for energy maximum of the system is obtained as well.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 3","pages":"88 - 93"},"PeriodicalIF":0.3,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4325045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. V. Aleksandrov, O. V. Aleksandrova, I. A. Kozik, Yu. S. Semenov
{"title":"A Modification of the Hodgkin–Huxley Model and a Mathematical Interpretation of the Principal Neurophysiological ‘‘All-or-None’’ Law","authors":"V. V. Aleksandrov, O. V. Aleksandrova, I. A. Kozik, Yu. S. Semenov","doi":"10.3103/S002713302103002X","DOIUrl":"10.3103/S002713302103002X","url":null,"abstract":"<p>The paper presents the results of simulation with the simplified modified Hodgkin–Huxley model of an afferent primary neuron in the presence of stochastic noise. The transition from the attraction domain of a point attractor like a stable focus to the attraction domain of a periodic attractor and the inverse transition to the attraction domain of the point attractor are considered. Some examples, in which such transitions may be repeatedly alternated, have been obtained as a mathematical interpretation of the principal neurophysiological ‘‘all-or-none’’ law.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 3","pages":"78 - 82"},"PeriodicalIF":0.3,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4325044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. V. Radkevich, O. A. Vasil’eva, M. I. Sidorov, M. E. Stavrovskii
{"title":"On the Raushenbakh Resonance","authors":"E. V. Radkevich, O. A. Vasil’eva, M. I. Sidorov, M. E. Stavrovskii","doi":"10.3103/S0027133021030055","DOIUrl":"10.3103/S0027133021030055","url":null,"abstract":"<p>The author’s method of thermodynamic analysis is used to single out two equations of state for the laminar combustion process: the classical Hugoniot adiabat, which determines the pressure, and the equation of state, which determines the entropy. This allows constructing a new mathematical model of the laminar process of vibrational combustion of a two-component mixture by closing the classical models of continuum mechanics. The model is phenomenological, which requires its verification. For numerical verification, the well-known experimental fact is chosen, the appearance of high-frequency acoustic vibrations described by B.V. Raushenbakh. The conditions for the origin of high-frequency oscillations are obtained in terms of the standard chemical potential. They can substantially disturb the combustion process and may cause a catastrophic break-up of the furnace of the engine structure. A numerical experiment established critical values of the standard chemical potential when high-frequency vibrations lead to destruction.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 3","pages":"65 - 77"},"PeriodicalIF":0.3,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4325729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the Invariant Correspondence between the Symmetric Second-Rank Tensors and the Vector Systems","authors":"D. V. Georgievskii","doi":"10.3103/S0027133021030031","DOIUrl":"10.3103/S0027133021030031","url":null,"abstract":"<p>The possibilities of various representations of high-rank tensors in three-dimensional space using lower-rank tensors, in particular, the representations of second-rank tensors by vector fields, is discussed. The purpose of these representations is a convenient geometric interpretation of certain mechanical properties of objects described by high-rank tensors. An invariant correspondence between symmetric second-rank tensors in three-dimensional space and pairs of vectors from the same space is proposed. On the basis of this correspondence, a geometric interpretation of the action of an isotropic symmetric tensor function of a tensor argument is given.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 3","pages":"83 - 87"},"PeriodicalIF":0.3,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4324061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Wiener Filter and Neural Network Filter for Measuring the Road Profile","authors":"Yu. V. Bolotin, P. A. Egorov","doi":"10.3103/S0027133021020035","DOIUrl":"10.3103/S0027133021020035","url":null,"abstract":"<p>Wiener filter and neural network filter are considered in relation to the problem of measuring the road profile. Road profile is identified using the inertial data from a smartphone rigidly fixed inside a moving car. The effectiveness of the approaches is compared by experimentally driving a car through a series of speed bumps.</p>","PeriodicalId":710,"journal":{"name":"Moscow University Mechanics Bulletin","volume":"76 2","pages":"44 - 49"},"PeriodicalIF":0.3,"publicationDate":"2021-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4110770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}