Doklady Physics最新文献

Samples of the Murchison meteorite (carbonaceous chondrite, type CM2) were kept isothermally in a specially designed device at temperatures of 200, 500, and 800°C. After the samples cooled down in an inert helium atmosphere, Raman scattering spectra were taken. An increase in the intensity of the G- and D‑lines of graphite was detected depending on the degree of heating. It is shown that using such a characteristic parameter of these lines as the area ratio, S_D/S_G, it is possible to define a geothermometer to determine the maximum temperature of thermal metamorphism of the parent bodies of carbonaceous chondrites. A comparison with the known data for carbonaceous chondrite Allende (CV3), which has experienced a significant thermal metamorphism, is carried out.

The derivation of the equation of static cylindrical bending of a thin plate under the action of pressures on its surface and end edges is given. The reduction over the thickness of the plate is taken into account, the effect of which becomes noticeable at high average pressure. The refined value of the transverse distributed force is used. The dependence of the bending on the average pressure and the rigidity of the supports in the longitudinal direction is considered.

The Fe–0.44%C–1.8%Si–1.3%Mn–0.82%Cr–0.28%Mo steel treated by the quenching–partitioning process showed a product of strength and elongation of 30 GPa % with yield stress of 1350 MPa. Such a combination of high ultimate tensile strength and good ductility is attributed to a high portion of retained austenite (≥20%) transforming to martensite under tension. The high yield stress is provided by carbon supersaturation of austenite and a high dislocation density in this phase.

Several statements of the problems of synthesis of a holographic mask in the form of optimization problems for quality of holographic images are presented. An effective algorithm for the synthesis of holographic masks based on FFT with the complexity O(NlnN), where N is the number of elements of the depicted object, is described. Based on this algorithm, a scalable software package has been developed and implemented that allows synthesizing holographic masks for various lithography applications, including the production of MEMS, MOEMS, and high-end chips. Experimental results are presented.

The worst disturbance problem for an oscillator with quadratic-law damping is stated. The role of the disturbance is played by an external force applied to the oscillator. It is assumed that this force acts in one direction, that the integral of this force with respect to time is given, and that at the initial instant of time the oscillator is resting in the equilibrium position. It is required to find a time history of the disturbing force that maximizes the maximum (with respect to time) of the absolute value of the displacement of the oscillator’s body from the equilibrium position. The worst disturbance from among rectangular pulses under which the disturbing force is constant on the initial time interval and is equal to zero outside of this interval is found and investigated.

An approach to creating compact and miniature infra- and low-frequency vibration isolation systems based on layered composite elastic elements with adjustable negative and quasi-zero stiffness is presented. New problems of modeling the given parameters of the stiffness and bearing capacity of elements of certain geometry under combined loading have been solved by varying the structure, elastic properties, and arrangement of layers and controlling the local mobility of the binder. The correctness of the approach is based on the results of experimental design and research of system models. This approach can qualitatively change the solution of a number of critical problems in vibroacoustics of aviation and other advanced engineering.

The results of study of the behavior of surface plasmon polaritons in the layered structure of a VO₂‒SiO₂-graphene-based hyperbolic metasurface under the influence of an external magnetic field before and at the beginning of the phase transition of vanadium dioxide are presented. As a result of calculations, it is shown how the isofrequency contour of surface plasmons changes taking into account the different direction of the external magnetic field. It is also shown how an external magnetic field affects the direction of static magnetization caused by the inverse Faraday effect. This work can offer additional ways to control the behavior of surface plasmons, as well as become the basis for the study of new self-adjusting structures.

Based on the energy approach to the process of brittle fracture, a new energy criterion for fracture was obtained in the case when an arbitrary normal symmetrical load acts on the surface of an isolated crack.

Based on analysis of the specific features inherent in the trajectory of a charged particle moving in an inhomogeneous electromagnetic wave, the physical processes determining the nature of ponderomotive forces are specified. In particular, the reason for switching the accelerated motion of a particle passing through an electrical field with zero amplitude in the direction perpendicular to the electrical field to deceleration with an increase in the electrical field amplitude is detailed. The effect of the inertial mass on the trajectory of a charged particle moving in an inhomogeneous electromagnetic wave is determined.

A numerical study of two-dimensional cellular detonation of a hydrogen–air mixture in channels of various widths was carried out, and data were obtained on the process of formation of a cellular structure and on the number, shape, and size of cells depending on the channel width. Based on the results of calculations, classification of two-dimensional cellular detonation structures was carried out. This study was carried out at the facilities of the Joint Supercomputer Center, Russian Academy of Sciences. The flow model of a multicomponent reacting mixture was implemented using a customized opensource solver of the OpenFoam framework based on the Kurganov–Tadmor scheme.