Improved Imaging Model in the Presence of Multiplicative Spatially Extended Cloaking Interference

The paper proposes an improved imaging model in the presence of multiplicative spatially extended cloaking interference. The model take into account the effect of multiplicative masking interference. To simplify the calculations of the image brightness in the distorted region the diagram technique is used. Unlike the known ones, the model takes into account the concentration of the distorting medium in a narrow squat layer, the primary reflection of solar radiation from the upper boundary of the distorting layer and subsequent multiple re-reflections of the transmitted radiation of the visible wavelength range from the earth’s surface and the upper boundary of the distorting medium layer. A technique for finding and taking into account the reflection and re-reflection coefficients of radiation to restore distorted images is proposed. The results of experimental studies are presented. For the experiment, the image of the territory of Iraq during the 2003 "Freedom for Iraq" hostilities was selected. Keywords— image, model, multiplicative, extended cloaking interference, spacecraft, reflection, coefficient

Nonlinear surface waves propagating along composite waveguide consisting of nonlinear defocusing media separated by interfaces with nonlinear response

The nonlinear surface waves propagating along the ultra-thin-film layers with nonlinear properties separating three nonlinear media layers are considered. The model based on a stationary nonlinear Schrödinger equation with a nonlinear potential modeling the interaction of a wave with the interface in a short-range approximation is proposed. We concentrated on effects induced by the difference of characteristics of the layers and their two interfaces. The surface waves of three types exist in the system considered. The dispersion relations determining the dependence of surface waves energy on interface intensities and medium layer characteristics are obtained and analyzed. The localization energy is calculated in explicit form for many difference cases. The conditions of the wave localization on dependence of the layer and interface characteristics are derived. The surface waves with definite energies in specific cases existing only in the presence of the interface nonlinear response are found. All results are obtained in an explicit analytical form.

Isothermal Oxidation Behavior of FGH720Li Superalloy at Service Temperatures

The oxidation behavior of FGH720Li(P/M Udimet720Li) superalloy was investigated under static atmosphere in temperature ranging from 600°C to 730°C. The oxidation kinetics, composition and morphology of the oxidation layers were characterized by means of isothermal oxidation tests, X-ray diffraction(XRD), scanning electron microscopy（SEM）and energy dispersive X-ray spectroscopy(EDS). The results showed that the oxidation kinetics curves of FGH720Li superalloy followed the parabolic law. The results of cross-sectional morphology and elemental distribution indicated that the oxidation layer could be divided into three parts：porous Cr2O3 outer layer, dense Cr2O3 medium layer and oxidation affected zone with nail-like Al2O3 inner layer. The oxidation process was primarily controlled by the diffusion of chromium and oxygen through the oxide scale.

RESEARCH OF VIBROREOLOGICAL MODELS OF LAYER OF BULK ENVIRONMENT

Vibration mechanics and vibroreology play an important role in the new section of applied vibration theory formed in recent years - the theory of vibration processes and devices. This theory studies the patterns of excitation and vibration in different mechanical systems; it also includes the theory of machines in which vibration is used to achieve useful goals. Based on the considered models, it was possible to describe the chaotic motion of the bulk medium layer over the vibrating plane. Such movements, well known for liquids, have indeed been observed in the case of a bulk medium, which serves as another confirmation of the possibility of modeling slow motions of a bulk medium during vibration in the form of viscous fluid motions (of course, with the above caveats and additions). When studying the described simplest models, motion (including we are interested in slow motion) can be found by directly using the solution of the problem of vibrotransportation of the body (particles). The value of this approach is determined, however, by the possibility of its application for an approximate solution in more complex cases. In the study of slow motions of bodies interacting with both the forces of dry friction and collisions, these interactions can be modeled by the forces of viscous friction, taking into account the driving vibration force. This leads to the following vibroreological approach to modeling the behavior of the bulk medium in vibrating trays and vessels. Of all the considered models, the most promising is the model of the behavior of the bulk medium under the influence of vibration in the form of a viscous medium.The described models can be used when considering a practically important task of vibration penetration into a free medium.

Backward waves leaving the metamaterial

The medium is composed of plane-parallel monolayers consisting of Huygens elements. In the molecular optics model, expressions are obtained for the reflected field, the field in the medium, and (in the case of a layer of finite thickness) behind the medium. An extinction theorem is considered, and an expression for the refractive index is introduced. Under certain conditions, such a medium can behave like a medium with a unit, zero, or negative real part of the refractive index at a given frequency. The condition for the realization of a magnetic mirror is formulated. In the case of a medium layer of finite thickness, the exit of backward waves outside the medium is shown.