Translated papers from the Chinese Preprint site, Chinaxiv
Showing 50 of 15540 papers
Generated abstract This paper studies the selection of a finite-difference step for numerical computation of derivatives on a uniform grid. It proves an asymptotic expansion for the central kth difference operator, showing that its leading discretization error is proportional to k times the square of the step and to t…
Generated abstract This paper examines the origin of the forbidden neutral oxygen lines at 6300 and 6364 Å in type I supernova spectra, focusing on the supernova in IC 4182. It argues that the observed emission can be explained by fluorescence in an expanding, initially highly ionized hydrogen envelope, analogous to t…
Generated abstract This paper experimentally investigates the initial gas-dynamic expansion and ionization kinetics of plasma produced by focusing a nanosecond neodymium laser pulse on a carbon target in vacuum. Using time-resolved slit streak photography of spectral lines from multiply charged carbon ions, together w…
Generated abstract The paper studies the large-index asymptotic behavior of eigenvalues of convolution integral operators on a finite interval when the Fourier transform of the kernel is a rational function, with particular attention to non-self-adjoint cases where the transform may be complex-valued. Using an analyti…
Generated abstract This paper reports visual observations of the color and brightness structure of the twilight aureole near the Earth’s horizon made from the Soyuz-5 spacecraft in January 1969. The authors describe the vertical sequence of colors under cloudless, continuous cloud, and broken cloud conditions, noting …
Generated abstract The crystal structure of paraoxyacetophenone was investigated by X-ray diffraction in connection with comparisons to benzophenone, which has the same space group but different piezoelectric behavior. Unit-cell parameters, density measurements, and Weissenberg intensity data showed that the orthorhom…
Generated abstract This paper examines apatite-like phases formed in the MeO, Nd2O3, SiO2 systems, where Me is Mg, Ca, or Ba, through heterovalent substitution of Nd3+ by divalent cations. Samples with nominal compositions of the type Me x Nd5-x(SiO4)3Oy were synthesized by prolonged firing at 1450 degrees C and analy…
Generated abstract The paper addresses the observation problem for nonlinear dynamical systems, specifically the determination of unmeasured phase coordinates or initial state values from measured output signals. It proposes embedding the nonlinear system in a parameter-dependent family whose zero-parameter member is …
Generated abstract This paper investigates how Forbush decreases in galactic cosmic rays affect the cosmic-ray-produced layer of the lower ionosphere at altitudes of about 50 to 80 km. Using nighttime long-wave radio absorption observations on the Brașov to Sofia path for 25 April to 12 May 1960, together with cosmic-…
Generated abstract This paper studies the existence of nontrivial positive solutions for nonlinear boundary value problems using cone methods in Banach spaces. It develops an abstract fixed point principle for a positive completely continuous operator satisfying a cone contraction condition and a Bernstein type a prio…
Generated abstract This paper studies time-optimal transitions for linear controlled systems with closed bounded convex control domains and closed convex endpoint sets, extending earlier optimality criteria beyond the case of a strongly stable terminal set and without assuming nondegeneracy. It reviews extremal proces…
Generated abstract This paper compares the acoustic efficiency of several underwater explosive sound sources relevant to marine seismic exploration, with emphasis on how emitted energy is distributed across frequency bands rather than on total acoustic output alone. Using an exponential approximation for shock-wave pr…
Generated abstract The paper studies the topology of classes of elliptic constant coefficient matrix differential operators in the plane, focusing on the connected components of operators satisfying a positivity condition for the associated matrix pencil. It gives a necessary and sufficient criterion, expressed throug…
Generated abstract The paper studies error distributions in linear discriminant analysis for two multivariate normal populations with common covariance when the dimension is comparable to the training sample sizes. It represents the Anderson classification statistic and the associated conditional error probabilities t…
Generated abstract This paper reports measurements of the electrical conductivity of synthetic diamond single crystals doped with aluminum and compares them with undoped crystals synthesized under similar conditions. Using a specially designed temperature-controlled contact apparatus and point-contact rectification te…
Generated abstract Observations of the pulsar MP 0628 were carried out at 86 and 105 MHz with a 12-channel receiving system on the Pushchino East-West radio telescope arm to study its meter-wave radio emission. The measurements show a dispersion measure of 34.36 pc cm-3, substantially larger than an earlier reported v…
Generated abstract This paper studies extremal problems for univalent functions in the class S through the structure of first variations and their associated Hilbert spaces. It introduces a positive bilinear form on variations of an extremal function, relates the second variation of linear coefficient functionals to a…
Generated abstract This paper establishes conditions for localization and uniform convergence of Fourier series associated with arbitrary fundamental systems of functions of the Beltrami operator on multidimensional domains or suitable Riemannian submanifolds. Using previously developed properties of such fundamental …
Generated abstract The paper studies restrictions on the cardinalities of infinite extremally disconnected bicompact spaces and complete Boolean algebras, using Stone duality and cardinal invariants such as type, weight, Suslin number, and algebraic weight. It develops embedding and generation arguments for complete B…
Generated abstract The paper studies when the Wallman compactification of a space coincides with the Ponomarev, Zaitsev compact extension defined via finite intersections of canonically closed sets. It introduces the notion of a seminormal space, a T1 space in which any two disjoint closed sets can be contained in dis…
Generated abstract The paper addresses the problem of constructing the transitive closure of a directed graph more economically than the standard cubic bound, focusing on the acyclic case as a component of a broader reduction for general graphs. It partitions the vertices of an acyclic graph into ranks and expresses t…
Generated abstract This paper studies the distribution in arithmetic progressions of integers of the form p(p′ + a), where p and p′ are primes, for prime moduli D that may grow with the main parameter. Using Vinogradov’s method for estimating trigonometric sums over primes, together with character sums and combinatori…
Generated abstract This paper studies the nonlinear, nonstationary impingement of antiparallel rarefied electron-proton plasma flows in a one-dimensional electrostatic model, with Boltzmann electrons and ions described by the Vlasov equation coupled to Poisson’s equation. A discrete charged-layer numerical method with…
Generated abstract The study investigates the temperature dependence of stimulated and unstimulated currents in polycrystalline cadmium selenide powder photoresistors between 77 and 273 K. Using sandwich-type cells measured in a cryostat after thermal resetting, the authors recorded current-voltage characteristics bef…
Generated abstract This note studies the continuous cohomology of the topological Lie algebra of smooth vector fields on a connected compact orientable smooth manifold. Building on earlier descriptions of the cohomology of formal vector fields, it introduces and analyzes filtrations of the standard cochain complex, as…
Generated abstract This paper examines how molecular anharmonicity affects the apparent vibrational relaxation time during excitation behind shock waves and during deactivation. Using shock tube ultraviolet absorption measurements for a 10 percent oxygen and 90 percent argon mixture and for nitrogen, the authors show …
Generated abstract This paper formulates differential games in mixed strategies for systems governed by ordinary differential equations when a value may fail to exist in pure strategies. Mixed controls are represented by time-dependent distribution functions and Lebesgue, Stieltjes measures on the players’ admissible …
Generated abstract The paper addresses the difficulty of extending maximum likelihood estimation from discrete Gaussian measurement vectors to continuously observed Gaussian processes, where the inverse of a correlation function cannot be used directly as a matrix inverse. It approximates the correlation function by a…
Generated abstract The paper studies lower bounds on the complexity of finite decision procedures for recursively enumerable sets, introducing the notion of effective nonrecursiveness in terms of unbounded recursive lower estimates. It analyzes enumerations of recursively enumerable sets, giving criteria involving reg…
Generated abstract The paper investigates mean values and partial sums of complex multiplicative functions under restrictions on their values at prime powers and on weighted prime sums. Building on Halász’s analytic method, the authors analyze the associated Dirichlet series near the line Re s = 1, establishing an alt…
Generated abstract The paper studies two problems in graph theory: finding minimum weight Hamiltonian circuits in directed and undirected graphs with integer edge or arc weights, and finding minimum edge coverings of graphs. It proposes a simple quadratic time algorithm that first constructs a long path and then inser…
Generated abstract This study examines the nature of chemical bonding in vanadyl complexes incorporated into oxide glasses, using electron paramagnetic resonance and electronic absorption spectra for phosphate, silicate, and borate systems containing vanadium. Interpreting the spectral parameters within molecular-orbi…
Generated abstract This paper examines whether the spatial extent of an earthquake source can be inferred from kinematic seismic data rather than treating the source as a single point hypocenter. The authors propose a procedure based on comparing first arrival time residuals for alternative hypocenters and grouping st…
Generated abstract This note studies inverse polyhedral representations of metric spaces, with emphasis on irreducibility, standardness, and behavior on systems of closed subsets. It extends results of Freudenthal, Isbell, and Pasynkov by proving that every sigma-locally finite system of closed subsets of a complete m…
Generated abstract This paper studies systems of nonlinear integral equations with deviating arguments under measurability, continuity, and boundedness assumptions on the kernels, deviations, and prescribed outside values. It proves compactness of the associated integral operator in a space of continuous vector functi…
Generated abstract This paper studies maximal functions formed from the partial sums of cosine and sine trigonometric series whose coefficients tend to zero and form a quasiconvex sequence. It proves asymptotic estimates for the integrals, away from the origin, of the majorants of these partial sums in terms of tail m…
Generated abstract This paper addresses the problem of measuring gravity from a moving marine base, where inertial accelerations and platform tilts can greatly exceed the gravity increments being sought. It proposes a method using the phase behavior of strongly damped pendulums: discrete gravimeter readings are select…
Generated abstract The paper studies asymptotic formulas for the number of solutions of Waring-type congruences modulo prime powers, especially in cases where such formulas may fail when the number of variables equals the exponent. It replaces the fixed right-hand side by a variable ranging over a short interval and i…
Generated abstract This paper examines the statistical properties of photocurrents produced by multiquantum photoelectric registration of radiation, extending earlier treatments focused on ordinary single-quantum detection. Within a semiclassical framework, it generalizes Mandel’s photoelectron-counting formula to a k…
Generated abstract The paper studies the number of integral solutions to the Thue equation defined by a binary form of degree at least three representing unity. Building on earlier finiteness results of Thue and uniform bounds known mainly for cubic forms, it addresses whether a bound depending only on the degree can …
Generated abstract The paper studies a necessary topological condition for Tikhonov regularizability of approximate solutions to injective equations between metric spaces. It proves that if such a problem is regularizable, then the images under the regularizing operators of any dense subset of the data space form a de…
Generated abstract The paper examines how integral conservation laws in general relativity can be derived from the covariant differential conservation law for a symmetric energy momentum tensor when spacetime admits a group of motions. By contracting the tensor with Killing vectors and applying Green’s formula in a Ri…
Generated abstract This paper examines the role of cementite, Fe3C, in diamond synthesis in the iron, graphite system under high pressure and temperature. The authors compare thermodynamic considerations with experiments at about 60 kbar and 1500 to 1600 degrees, including tests on iron, graphite mixtures of varied co…
Generated abstract This paper studies minimax time-to-encounter differential games for systems with additive controls of two players, using approximation strategies defined through set-valued contingent dynamics. It introduces stability and absorption notions for families of closed sets and constructs extremal strateg…
Generated abstract This paper studies steady finite-amplitude capillary-gravity waves on an ideal incompressible liquid of infinite depth, forced by a periodic pressure distribution on the free surface. Using conformal mapping, Bernoulli’s condition with surface tension, and Dini relations, the boundary-value problem …
Generated abstract This paper derives approximation formulas for the polarizability tensor of a homogeneous dielectric body and for the electrostatic capacitance of a conductor of arbitrary shape. The formulas are expressed through surface integrals over the boundary, with error estimates showing geometric convergence…
Generated abstract The paper develops an asymptotic averaging method for nonsinusoidal waves in arbitrary nonlinear first-order partial differential systems, including cases with slow inhomogeneity, nonstationarity, and possible nonconservative terms. Starting from a family of periodic stationary plane-wave solutions,…
Generated abstract This paper studies the metric classification of decreasing sequences of measurable partitions of Lebesgue spaces, with emphasis on homogeneous dyadic sequences whose finite initial segments are all isomorphic. It introduces the accompanying partition and universal projectors as tools for identifying…
Generated abstract The crystal structure of the double fluoride BaTm2F8, formed in the BaF2, TmF3 system, was determined from single crystal X-ray diffraction data because no structural analogues were known. Using heavy atom methods, Patterson and electron density projections, and least squares refinement, the authors…
Generated abstract This paper examines surface breakdown when gas electrodes contact a solid dielectric or semiconductor, focusing on the transition between discharge along the gas interface and breakdown through the solid. The authors model the gas and solid as parallel conductive paths with strongly nonuniform field…
