Academician I. I. ARTOBOLEVSKII
This paper derives linearly enveloping coupler curves for a general four-link ellipsograph whose sliders move along guides at an arbitrary fixed angle, and for an inverse ellipsograph mechanism. Using instantaneous centers of rotation, perpendicular projections, and parametric equations for the corr…
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This paper examines the kinetic energy spectrum of locally homogeneous and isotropic turbulence in an incompressible fluid at wave numbers beyond the Kolmogorov inertial range, where viscous effects become important. Using the vorticity transport equation in a deforming fluid element, it models the …
1. For a prescribed trajectory of motion, the acceleration due to reactive thrust is a given quantity
The paper formulates an optimization problem for the reactive motion of a variable mass body in a gravitational field, assuming constant useful power expenditure. It derives the mass and weight relations for a prescribed thrust acceleration history, showing that minimizing the required initial reser…
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This paper establishes an analogy between plane potential flow of an ideal incompressible fluid and the plane trajectory problem for a material point in a conservative field at fixed energy. Starting from Jacobi’s least action principle, it derives a trajectory equation in terms of the logarithm of …
G. S. BARKHIN and V. T. FOMENKO
This note studies bending and rigidity of pieces of surfaces of positive Gaussian curvature with boundary conditions imposed on the normal curvature and geodesic torsion of the contour. The authors reformulate the Gauss and Codazzi equations for increments of the second fundamental form as a boundar…
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The paper studies the motion of the interface between two immiscible viscous fluids in a narrow slot, emphasizing the role of interfacial tension in Hele-Shaw type flows used to model filtration in porous media. Using potential theory, the pressure field is represented by logarithmic single and doub…
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This paper studies the unsteady boundary-layer flow past a flat plate of a viscous incompressible electrically conducting fluid in a constant transverse magnetic field, assuming negligible induced magnetic field and unit Prandtl number. The magnetohydrodynamic momentum and energy equations are refor…
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This paper examines acoustic instability in the combustion of condensed systems in a one-dimensional tube, motivated by the difficulty of directly measuring the acoustic impedance of a burning surface and by ambiguities in more complex combustion geometries. The authors formulate the linear stabilit…
V. N. VILYUNOV
This paper develops a theoretical treatment of erosive burning, the increase in propellant burning rate caused by turbulent gas flow over a burning surface. Starting from stationary combustion theory, it formulates coupled momentum, heat, and species equations with turbulent transport terms, then de…
Corresponding Member of the Academy of Sciences of the USSR A. V. Pogorelov
This note studies elastic postcritical deformations of cylindrical shells hinged at the edges under uniformly distributed external pressure, focusing on large deflections beyond the scope of linear theory. The analysis approximates the postcritical shell shape by an isometric surface developed from …
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The paper examines the in plane stability of a rectangular elastic strip compressed by uniform pressure on two opposite sides, addressing earlier treatments in which higher order effects were retained in boundary conditions but neglected in equilibrium equations. Using Novozhilov’s equilibrium equat…
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This paper studies exact magnetohydrodynamic motions of a conducting medium with finite electrical conductivity moving parallel to one axis in a plane magnetic field. Starting from the magnetohydrodynamic equations and using a vector potential representation, it derives conditions on the magnetic fi…
L. M. LYAMSHEV
This paper derives integral relations of reciprocity type for acoustic fields in a homogeneous moving gas containing stationary thin elastic bodies such as plates and cylindrical shells. Because ordinary acoustic reciprocity does not generally hold in a moving medium, the analysis formulates two adj…
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This paper analyzes steady radial flow of a viscoplastic medium in the narrow gap between two identical rough parallel disks rotating about a common axis. Using thin-gap approximations for the equilibrium equations and a Bingham-type relation with plastic viscosity and limiting shear stress, it deri…
The motion is assumed to be plane, steady, and irrotational; the liquid is ideal and incompressible.
This paper studies plane, steady, irrotational flows of an ideal incompressible liquid with a free boundary having horizontal asymptotes, focusing on flow over a locally uneven bottom and on solitary waves. The free-boundary problem is transformed by conformal mapping to an infinite strip and reduce…
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This paper develops an averaging approach for nonlinear oscillatory systems governed by Lagrange equations under weak external forces. It first transforms the perturbed Lagrange equations by treating the constants of the unperturbed motion as time-dependent variables, deriving exact evolution equati…
E. V. Stupochenko and I. P. Stakhanov
This paper formulates and analyzes equations for relaxation hydrodynamics in media where local thermodynamic equilibrium is established on a time scale comparable with hydrodynamic variation, as in high-frequency sound or supersonic flows. Introducing a nonequilibrium parameter and a phenomenologica…
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The paper analyzes the elastic stability of a circular cylindrical shell reinforced by uniformly spaced identical rings and subjected to external pressure, with hinged shell edges assumed in the formulation. The authors treat shell spans and rings as separate interacting elements, express displaceme…
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This paper examines the creep of ice and frozen skeletal soils under simple and complex stress states, based on long-duration experiments involving compression, tension, bending, shear, and combined torsion with longitudinal compression. It refines constitutive relations for steady and initial creep…
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The paper develops an approximate dynamic model for plane motion of a compressible plastic medium, replacing incompressibility by a linear relation between stress and strain-rate invariants while retaining the Prandtl-Reuss plasticity and coaxiality conditions. Using compatibility conditions for wea…
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This paper treats the linearized hydrodynamic problem of wave resistance for an arbitrary rigid body moving at constant angular velocity along a horizontal circular path beneath the free surface of an ideal heavy liquid of infinite depth. It derives expressions for the wave velocity potential for mo…
V. E. GUL’, V. V. KOVRIGA, and A. N. KAMENSKII
This study examines how the relaxation behavior of cross-linked butadiene-nitrile rubber vulcanizates can be evaluated during rupture through the rate of spontaneous contraction after failure. Using high-speed cinematography, the authors measured contraction in notched plates and narrow strips of SK…
D. D. IVLEV
This paper examines the construction of constitutive relations between the rate of deformation tensor and the stress tensor for a homogeneous, isotropic, incompressible viscous fluid satisfying Newton’s law in pure shear. Using a potential of deformation rates, including a generalized potential for …
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The paper studies the existence of steady periodic gravity waves of non-small amplitude, extending earlier small-amplitude treatments of Nekrasov’s formulation. By recasting the free-boundary problem as a nonlinear integral equation in a cone and applying the theory of positive operators, it proves …
Corresponding Member of the Academy of Sciences of the USSR L. N. SRETENSKII
This paper summarizes an analytical treatment of the reflection of tsunami-like long waves from a straight shoreline in a rotating basin of constant depth. Starting from the linear long-wave equations with Coriolis terms, the surface elevation is decomposed into steady and unsteady components, and t…
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This paper examines hydrodynamic calculations for flows of gasified liquids when relative permeabilities depend on two parameters rather than on saturation alone. The authors discuss the applicability of permeability data obtained from steady linear filtration to plane-radial and well-system flows, …
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This note develops a general scheme for representing certain axisymmetric unsteady adiabatic motions of a perfect gas as power series in the radial coordinate in spherical coordinates. Using the structure of the gas-dynamic equations, the author shows that, when the leading velocity terms are nonzer…
G. I. BARENBLATT and Yu. P. ZHELTOV
The paper formulates continuum equations for unsteady filtration of a homogeneous fluid in rocks with strongly developed fracturing, where explicit modeling of individual fractures is impractical. It represents the rock as two interacting porous media, a highly permeable fracture system and a lower …
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This paper studies the motion of an incompressible electrically conducting viscous fluid between two parallel porous planes under a constant transverse magnetic field, with injection through one plane and suction through the other. The magnetohydrodynamic equations are reduced to coupled equations f…
F. I. FRANKL’
The paper studies the direct problem of steady flow past a smooth profile by a sonic stream, treated in first approximation by the hodograph method. Starting from earlier inverse constructions and from known solutions for polygonal profiles, it linearizes the boundary conditions for a small perturba…
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The paper analyzes a converging spherical shock wave in a plastic compressible medium under a simplified compression law in which material behind the front reaches a limiting density. Using Lagrangian variables, the author derives equations for motion, pressure, and velocity in a spherical layer wit…
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This paper constructs approximate unsteady transonic potential flows of an ideal gas near the critical section of a Laval nozzle with two symmetry planes. Starting from the standard unsteady transonic equation, the authors introduce a special form of the axial velocity perturbation that reduces the …
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This paper reports field experiments designed to test a continuum model for the dynamic behavior of soft sandy soils under blast loading, where classical elasticity is inadequate. TNT explosions were used to generate centrally and cylindrically symmetric stress waves, with radial and principal stres…
S. V. Vallander
This paper proposes a system of integral kinetic equations for monatomic gases intended to incorporate both intermolecular collisions and boundary interactions with immersed bodies. It defines distribution, internal and boundary birth functions, a free motion probability, and impact transforms for g…
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This note develops aspects of Prager’s theory of ideally hardening media for homogeneous, isotropic, incompressible materials whose response is invariant under stress reversal. It argues, by an extremal work assumption, that the appropriate hardening condition is represented in principal strain spac…
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This paper reports experiments on the limiting load-bearing capacity of annealed thin-walled technically pure nickel tubes subjected to axial tension, torsion, and internal pressure along proportional and complex loading paths. True stresses and strains at limiting load were measured, and limiting s…
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This paper examines postcritical elastic deformations of strictly convex shells, focusing on buckling states in which the shell shape differs substantially from its initial configuration. It argues that bulging in geometrically non-bendable convex shells is well approximated by mirror reflection of …
N. M. MITROKHIN and Yu. I. YAGN
This paper examines systematic deviations from two common assumptions of plasticity under simple loading: similarity of stress and strain deviators and a unique relation between stress intensity and strain intensity independent of stress state. Experiments on annealed technically pure nickel tubular…
The system of equations of spatial unsteady motion of a polytropic gas has the form
The paper studies exact double-wave solutions of the equations for spatial unsteady motion of a polytropic gas, without assuming potential flow. Using a modified method based on common two-dimensional planar level surfaces, it reduces the governing gas-dynamic system to algebraic and differential co…
L. A. DIKII
This paper examines the stability of plane parallel flows of an inviscid fluid, emphasizing that the usual analysis by normal wave solutions is insufficient because such solutions need not form a complete representation of arbitrary perturbations. The author formulates and solves the Cauchy problem …
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This paper formulates Lagrangian statistical characteristics of turbulence and relates them to Eulerian descriptions, with emphasis on turbulent and relative diffusion in incompressible fluids. It discusses probability distributions for particle coordinates and velocities, derives relations between …
Under the assumptions made, the equations of hydrodynamics may be written in the following dimensionless form:
This paper analyzes the steady axisymmetric motion of a compressible, inviscid, weakly conducting gas jet in a prescribed axisymmetric magnetic field, neglecting thermal conductivity, viscosity, charge density, and electric field. Treating the electromagnetic interaction parameter as small, it expan…
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This paper investigates how normal and shear stresses develop during the transition from rest to steady shear flow in a 2 percent aluminum naphthenate gel in vaseline oil. Using a cone and disk rheogoniometric attachment to an elastoviscometer, the authors simultaneously measured tangential and norm…
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This paper analyzes the motion and systematic azimuth deviation of a gyroscopic compass with mercury ballistic vessels when ship rolling is modeled as a stationary random process rather than as a sinusoidal motion. Starting from the linearized compass equations, it derives spectral expressions for t…
G. E. KUZMAK
This paper studies the spatial motion of an axisymmetric rigid body about a fixed point under a restoring moment and small damping moments whose coefficients vary slowly in time. Using the method of model equations, it constructs asymptotic expressions for the nutation angle and precession velocity …
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The paper constructs the Green tensor for the equilibrium problem of a shallow rectangular shell of double curvature under boundary fastening conditions. Using Kilchevskii’s integral-equation method, the authors transform the displacement equations by choosing auxiliary displacements that satisfy th…
Applying to the system of equations (1)
This letter revisits a previously published proof of uniqueness for the symmetric solution of the large deflection problem for a symmetrically loaded circular plate. It notes that the earlier argument, based on the Hildebrandt-Graves theorem, established only local uniqueness, and supplies an additi…
L. I. RUBINSHTEIN
This paper studies a thermoconvective boundary-contact problem with concentrated capacity, motivated by heat injection through a unit well into a thermally anisotropic reservoir. Using Laplace, Carson, and Fourier, Bessel integral transforms, it reduces the governing parabolic equations and contact …
S. M. BELONOSOV
This paper treats the plane elasticity problem for a wedge with prescribed boundary stresses or displacements, formulated in terms of Muskhelishvili complex potentials. By mapping the wedge to a half-plane and applying a one-sided Laplace transform, the boundary-value problem is reduced to an integr…
I. A. URUSOVSKII
This paper analyzes the plane problem of acoustic diffraction by a periodically uneven and inhomogeneous surface with prescribed normal acoustic conductivity. Starting from an integral equation for surface pressure, it derives a finite-difference equation for its Fourier transform, reduces the probl…