Translated papers from the Chinese Preprint site, Chinaxiv
Showing 50 of 15526 papers
Generated abstract The paper studies conditions under which systems of ordinary differential equations with a principal positively homogeneous term admit proper guiding functions in the sense of Krasnosel’skii. It proves a necessary and sufficient criterion for constructing a homogeneous function with a prescribed pos…
Generated abstract An asymptotic method is developed for weakly nonlinear one-dimensional distributed systems with dispersion, aimed at problems of wave propagation and interaction where expansions in normal modes with time-dependent parameters are insufficient. The approach represents multiwave quasiharmonic solution…
Generated abstract This paper studies values of L(1, χD) for real Dirichlet characters when the modulus D is restricted to sparse arithmetic progressions and related sets. Using estimates for double sums with quadratic Dirichlet characters, it derives a main lemma reducing asymptotics for moments of modified L-values …
Generated abstract Marine reflected-wave seismic profiles acquired in 1968 near the southern Kuril Islands are used to examine the structure of the Central Kuril trough, the Vityaz Ridge, and the adjacent slope of the Kuril-Kamchatka trench. Time sections along profiles near Iturup Island are interpreted in comparison…
Generated abstract This paper studies linear equations for functionals involving higher order functional derivatives in normed spaces, with Cauchy data specified at a point. Using Frobenius-type complete integrability conditions, it formulates solvability criteria, including explicit conditions for a second-order equa…
Generated abstract This paper analyzes thermal distortions in solid state laser resonators whose neodymium glass active element has the form of a thin rectangular plate rather than a circular rod. Using thermoelastic relations for a free plate with a symmetric temperature distribution through its thickness, the author…
Generated abstract This note studies coefficient sequences in expansions with respect to seminormalized bases in uniformly convex and uniformly smooth Banach spaces, with special attention to Hilbert spaces. It proves upper and lower norm estimates in terms of sequence norms, derives a stability theorem for bases in u…
Generated abstract This paper studies nonlinear Hammerstein type equations of the form x + BFx = f in a complex Hilbert space, where F is a bounded hemicontinuous monotone nonlinear operator and B is a densely defined closed linear operator not assumed to be bounded or self-adjoint. Using monotonicity and coercivity h…
Generated abstract The paper studies quasistatic boundary value problems in the linear theory of thermo-viscoelasticity with contact-type boundary conditions, using operator notation based on relaxation and creep kernels and the Laplace-Carson transform. It establishes uniqueness under standard positivity conditions o…
Generated abstract This study examines the high-temperature stability of synthetic fluorophlogopite and several isomorphous synthetic micas, a property for which earlier reported limits varied widely. Samples were annealed between 700 and 1300 °C for 70 to 140 hours and analyzed by continuous thermogravimetry, chemica…
Generated abstract This paper studies qualitative stability and instability in the large for a class of discrete amplitude-pulse automatic control systems consisting of a linear difference equation coupled to nonlinear modulators with memory. Using quadratic forms, transfer-function conditions on the unit circle, and …
Generated abstract The paper presents a method for solving systems of linear algebraic equations with symmetric positive definite matrices by interpreting them as Ritz systems for a functional equation in an energy space. It derives an algorithm based on orthonormalizing a corresponding system of vectors, showing that…
Generated abstract This paper examines stresses arising during axisymmetric buckling of thin spherical shell segments, focusing on an experimental check of a previously derived formula relating stress to shell thickness, local bending geometry, and material properties. Instead of measuring stress directly, the study m…
Generated abstract The paper presents an iterative method for constructing cubic and polycubic spline functions by formulating spline interpolation as a boundary value problem for fourth order differential equations with coefficients vanishing at interpolation nodes. After finite difference discretization on a refined…
Generated abstract This paper proves uniqueness for a Tricomi boundary value problem for a class of nonlinear mixed type equations of the form \(y^m u_{xx}+u_{yy}=f(x,y,u)\), where the equation is elliptic in the upper half plane, hyperbolic in the lower half plane, and degenerates on the line \(y=0\). Under continuit…
Generated abstract This paper examines the remote determination of surface soil characteristics from microwave thermal radio emission. Using a model for the radio-brightness temperature of a semi-infinite medium and an empirical approximation of the soil temperature profile, it derives relations between measured brigh…
Generated abstract This paper investigates the orientation dependence of characteristic X-ray spectral line parameters for vanadium atoms in a single crystal of vanadium pentoxide. Using X-ray spectrometry with the crystal as a rotatable anode, the authors measured the spectral position, maximum intensity, half-width,…
Generated abstract This paper reports the synthesis and microscopic characterization of NiAsS formed by nickel diffusion into As-S glass at 450 to 600 degrees C and 30 to 70 kbar. Optical and X-ray analyses identify the product with the gersdorffite structure, while polished sections reveal that the crystallites are n…
Generated abstract This paper proposes a variant of the method of successive approximations for numerical integration of two-dimensional incompressible Prandtl boundary-layer equations with an arbitrary pressure gradient, assuming that a solution exists. The method integrates the momentum equation with respect to the …
Generated abstract This paper proposes and analyzes a continuous-wave carbon dioxide laser in which the usual gas-discharge excitation is replaced by optical pumping from an alkali-metal resonance lamp. The authors describe an excitation chain in which resonant absorption by alkali-metal atoms transfers energy through…
Generated abstract This paper investigates whether a monoenergetic, well collimated proton beam can be used as a diagnostic of turbulent collective oscillations in a plasma. A 50 keV proton beam was passed through the turbulent plasma of a high voltage direct discharge, and time resolved beam broadening was recorded i…
Generated abstract This paper develops analytical expressions for the yield of characteristic X-ray photons emitted into one steradian per incident ionizing particle, as a parameter for comparing primary spectra excited by electrons and secondary spectra excited by X-ray photons. Using excitation-density models that i…
Generated abstract This note studies multiplier transformations that replace the symbol of a pseudodifferential operator by its product with a function depending on frequency and space variables, asking when such transformations preserve boundedness in spaces \(L_p(R^m)\). It introduces function space conditions on th…
Generated abstract The paper studies the first boundary-value problem for a class of quasilinear systems in divergent form, formulated through abstract additive homogeneous operators and variable Orlicz, Sobolev-type spaces. Building on a theorem of Browder and Dubinskii, it introduces structural, coercivity, monotoni…
Generated abstract This paper estimates electron positron pair production when intense focused laser radiation irradiates a dense, initially nonrelativistic plasma. The authors argue that, at attainable laser intensities, pair creation involving electron scattering by nuclei is far more probable than production by int…
Generated abstract This paper investigates how amorphous boundary layers can preserve and transmit structural information from crystal surfaces, focusing on a proposed photoelectret mechanism in selenium films deposited on NaCl cleavage surfaces. Amorphous selenium layers were formed under controlled illumination cond…
Generated abstract This paper gives elementary constructions of universal functions for partial recursive functions using a polynomial pairing-like map on natural numbers. It proves that any partial binary arithmetical operation satisfying three simple identities relative to this polynomial is recursively complete, an…
Generated abstract This paper derives asymptotic formulas for the global error in numerical solutions of Cauchy problems for systems of ordinary differential equations. Under smoothness assumptions on the right-hand side and bounded local and round-off errors, it presents expansions for third- and fourth-order Runge-K…
Generated abstract This paper examines whether a decompression, or density decrease, zone may exist in the upper mantle corresponding to the seismic low-velocity layer, contrary to mantle density models that assume only positive density gradients. It reviews earlier rheological, thermodynamic, and seismological argume…
Generated abstract The paper presents a fitting method for solving the two-dimensional variometric inverse problem of potential theory, aimed at determining the contour of a subsurface body of constant excess density from measured horizontal gravity gradients. The variometric formulation is reduced to a gravimetric in…
Generated abstract This paper analyzes the dynamic buckling of cylindrical fiberglass shells treated as orthotropic under axial impact by a finite striking mass, including the effect of initial geometric imperfections. The authors formulate the problem using nonlinear shell equations, approximate rhomboidal dent shape…
Generated abstract This paper studies polynomial approximation of continuous functions on bounded convex polyhedra in multidimensional Euclidean space, with attention to improved local estimates near vertices. It proves that for a function on a convex polyhedron there are polynomials whose error is controlled by the k…
Generated abstract This paper studies regular differential operators on the basic affine space of a connected semisimple algebraic Lie group over an algebraically closed field of characteristic zero. It introduces a projection-like operation from regular functions on the group to regular functions on the quotient by t…
Generated abstract This paper examines thermo-optical properties of neodymium-activated laser glasses, motivated by thermal gradients in optically pumped glass rods that can distort resonator wavefronts despite high initial optical homogeneity. It presents a direct interferometric method for measuring the thermo-optic…
Generated abstract This paper investigates the origin of hole conductivity in selenium and the role of oxygen impurities in determining carrier type. The authors measure electrical conductivity and thermoelectric emf in amorphous selenium with varying crystallinity and in single crystalline hexagonal selenium before a…
Generated abstract This paper studies differential games in which the payoff is the time required for a controlled trajectory to reach a target set, under restrictions on admissible phase states. The constrained motion is modeled by adding a normal reaction term to the differential inclusion, and the author extends no…
Generated abstract This note studies the optimization of algorithms for numerical differentiation, numerical integration, and interpolation on classes of functions modeled by generalized Sobolev-type Hilbert spaces. Using the functional-analytic principle of minimizing the norm of the corresponding error functional, t…
Generated abstract This paper examines borderline conditions for convergence in the L metric of trigonometric Fourier series and their conjugate series. It constructs a summable periodic function whose integral modulus of continuity, and that of its conjugate function, are both of order 1 divided by log 1 over delta, …
Generated abstract This paper examines electron, phonon interaction in Nd3+ activated Y3Al5O12 crystals through temperature dependent induced emission spectroscopy. The authors analyze how generation energy, line width, wavelength shift, and saturation behavior vary with temperature, comparing experimental data with k…
Generated abstract The paper studies an algebraic representation problem arising in control theory for a controllable linear system with a Hermitian form in the state and input variables. It seeks conditions under which the form can be written as the derivative of a quadratic Lyapunov-type expression plus a quadratic …
Generated abstract This paper studies a differential game of approach in which two players choose constrained controls entering jointly, rather than separately, in the system dynamics. It formulates the problem in the class of mixed approximating strategies, introduces extremal strategies and a modified notion of posi…
Generated abstract The paper proves that the Hilbert parallelepiped, or Hilbert cube, cannot be represented as a countable union of proper closed subsets whose pairwise intersections are weakly infinite-dimensional. The argument develops several auxiliary results on weakly infinite-dimensional spaces, normal adjoining…
Generated abstract The paper reports radio astronomical measurements of right ascensions for Galactic sources of anomalously excited OH emission, motivated by the need to identify OH regions with infrared and other astronomical objects. Observations were made in 1969 with the Large Pulkovo Radio Telescope at 1612 MHz …
Generated abstract This study applies the solubility method to examine isomorphous substitution in yttrium aluminum and yttrium gallium garnets containing neodymium, using a PbF2, PbO, and B2O3 melt as solvent at 1100 °C. Solubility isotherms were obtained for systems involving Y3Al5O12, Y3Ga5O12, Nd3Al5O12, and Nd3Ga…
Generated abstract This note revisits a theorem of M. V. Keldysh and M. A. Lavrentiev concerning boundary behavior of nonconstant harmonic functions attaining their lower limiting value at a boundary point, with implications for uniqueness in the Neumann problem. It extends the result from a three-dimensional parabolo…
Generated abstract The paper studies Darboux problems for a second order hyperbolic equation whose coefficient of the second \(x\)-derivative may vanish on the boundary line, allowing parabolic degeneration. Using a weighted energy identity, an exponential change of unknown, and suitable choices of weights, it proves …
Generated abstract The paper studies uniqueness for the Cauchy problem for general linear partial differential equations with constant coefficients and zero initial data, under growth restrictions imposed only on one spatial half-axis rather than on the whole line. Using the Newton-Puiseux asymptotics of the roots of …
Generated abstract This paper reports spectrophotometric observations of the Earth and its atmosphere made from the Soyuz-7 spacecraft during the October 1969 group flight, extending earlier measurements from Soyuz-5. Using a modified hand-held RSS-2 spectrograph, the authors measured the twilight halo and the spectra…
Generated abstract This note studies boundary behavior of the Poisson integral in a half-space and applies it to the Dirichlet problem for the Laplace equation with very general boundary data. It states several Fatou-type results showing when derivatives and mixed derivatives of the Poisson integral converge to corres…
Generated abstract The paper studies conditions under which topological and metrizable spaces can be compactified or condensed onto compacta, with special attention to points of noncompactness and non-pi-compactness. It shows by examples that compactifiability onto compacta is not determined simply by the correspondin…
