Thermally excited vibrations of aircraft structural elements

This paper considers the axisymmetric transverse vibrations of aircraft nonuniform structural elements that are introduced by a thermal shock. Analytical solutions have been obtained and their numerical analysis has been performed.     

Results of solar observations by the CORONAS-F payload

The CORONAS-F mission experiments and results have been reviewed. The observations with the DIFOS multi-channel photometer in a broad spectral range from 350 to 1500 nm have revealed the dependence of the relative amplitudes of p-modes of the global solar oscillations on the wavelength that agrees perfectly well with the earlier data obtained in a narrower spectral ranges. The SPIRIT EUV observations have enabled the study of various manifestations of solar activity and high-temperature events on the Sun. The data from the X-ray spectrometer RESIK, gamma spectrometer HELICON, flare spectrometer IRIS, amplitude–temporal spectrometer AVS-F, and X-ray spectrometer RPS-1 have been used to analyze the X- and gamma-ray emission from solar flares and for diagnostics of the flaring plasma. The absolute and relative content of various elements (such as potassium, argon, and sulfur) of solar plasma in flares has been determined for the first time with the X-ray spectrometer RESIK. The Solar Cosmic Ray Complex monitored the solar flare effects in the Earth’s environment. The UV emission variations recorded during solar flares in the vicinity of the 120-nm wavelength have been analyzed and the amplitude of relative variations has been determined.     

Precipitation of subrelativistic-energy electrons near the polar boundary of the Earth radiation belt according to the data of measurements on the <Emphasis Type="Italic">Vernov</Emphasis> and <Emphasis Type="Italic">Lomonosov</Emphasis> satellites

The work is devoted to observations of sharp growths of magnetospheric electron fluxes in the vicinity of the polar boundary of the outer radiation belt of the Earth according to the data of measurements on the Vernov and Lomonosov satellites. This precipitation was observed at the high-latitude boundary of the outer radiation belt toward the equator from the isotropization boundary, and can be caused by scattering waves of various physical natures, including electromagnetic and electrostatic waves.     

Numerical scheme of the second order of accuracy for vortex methods for incompressible flow simulation around airfoils

A high-accuracy numerical scheme is proposed for vortex methods of flow simulation around airfoils of arbitrary shape including airfoils with sharp edges, because it does not require the solution continuity on the airfoil.     

Influence of the helicopter flight design speed on the selection of working process parameters for GTE

This paper considers issues of designing a gas-turbine engine in the helicopter system at the early design stages. The optimum and rational values of engine working process parameters at different flight speeds of the flight vehicle (FV) are analyzed. Several characteristics of mathematical models (MM) that form the helicopter–engine system, are described.     

Fuzzy logic rule as a method for making a design decision in rocketry development

The paper provides a method for multi-criteria selection of the optimal structural layout option based on a fuzzy logic inference that allows for uncertainties in engineering and operates with heterogeneous information of the qualitative and quantitative nature for the systems being designed.     

Gamma ray bursts: Short vs. long

Short and long GRBs are thought to be two distinct classes based on their different duration and spectrum. Through the spectral analysis of two similarly selected samples of BATSE short and long GRBs, we show that short GRBs are harder than long events, confirming what found from the comparison of their hardness ratio. However, this spectral diversity seems to be due to a harder low energy spectral component of short GRBs, rather than a (slightly higher) peak energy. Interestingly short GRBs have a spectrum which is similar to the spectrum of the emission of the first 1–2 s of long events. We find evidence that short GRBs are inconsistent with the E_peak–E_iso correlation defined by long bursts while they follow the same E_peak–L_iso correlation of long GRBs. These results, coupled to the similar variability timescale of short events and the first seconds of long ones, suggest that a common (or similar) dissipation mechanism could operate in both classes. The difference in the duration would then be due mainly to the central engine lifetime.     

OSIRIS-REx low-velocity particles during outbound cruise

We analyzed high-angular rate streaks first recorded by OSIRIS-REx’s MapCam during a 2017 search for Earth Trojan asteroids. We interpret them as water-ice particles that translated across the imager’s field of view, originating from the spacecraft itself. Their translation velocities approximated 0.1–1?m/s based on reasonable conclusions about their range. Pursuing several lines of investigation to seek a coherent hypothesis, we conclude that the episodic releases of the water ice particles are associated with spacecraft attitudes that resulted in solar illumination of previously shadowed regions. This correlation suggests that the OSIRIS-REx spacecraft itself possesses micro-climatic zones consisting of hot regions and cold traps that may temporarily potentially pass volatiles back and forth before losing most of them.     

Large-scale flows of viscous incompressible vortical fluid

An exact solution of the Navier - Stokes equations is given that describes the vorticity of a viscous incompressible liquid or gas, dissipative mediums, stationary shear counter-current of continuous vortical medium in the absence of the Coriolis field.