Modeling Pulsar Wind Nebulae

In the last few years, new observations by CHANDRA and XMM have shown that Pulsar Wind Nebulae present complex but similar inner features, with the presence of axisymmetric rings and jets, which are generally referred to as a jet-torus structure. Due to the rapid growth in accuracy and robustness of numerical schemes for relativistic fluid-dynamics, it is now possible to model the flow and magnetic structure of the relativistic plasma responsible for the emission. Recent results have clarified how the jet and rings are formed, suggesting that the morphology is strongly related to the wind properties, so that, in principle, it is possible to infer the conditions in the unshocked wind from the nebular emission. I will review here the current status in the modeling of Pulsar Wind Nebulae, and, in particular, how numerical simulations have increased our understanding of the flow structure, observed emission, polarization and spectral properties. I will also point to possible future developments of the present models.     

Diffusion coefficients of multicomponent combustion product mixture

The behavior of generalized diffusion coefficients and diffusion flows of individual substances in the multicomponent gas mixture is investigated. The combustion products of liquid rocket propellants being used are considered.     

Solar Isotopic Composition as Determined Using Solar Energetic Particles

Solar energetic particles (SEPs) provide a sample of the Sun from which solar composition may be determined. Using high-resolution measurements from the Solar Isotope Spectrometer (SIS) onboard NASA’s Advanced Composition Explorer (ACE) spacecraft, we have studied the isotopic composition of SEPs at energies ≥20 MeV/nucleon in large SEP events. We present SEP isotope measurements of C, O, Ne, Mg, Si, S, Ar, Ca, Fe, and Ni made in 49 large events from late 1997 to the present. The isotopic composition is highly variable from one SEP event to another due to variations in seed particle composition or due to mass fractionation that occurs during the acceleration and/or transport of these particles. We show that various isotopic and elemental enhancements are correlated with each other, discuss the empirical corrections used to account for the compositional variability, and obtain estimated solar isotopic abundances. We compare the solar values and their uncertainties inferred from SEPs with solar wind and other solar system abundances and find generally good agreement.     

On improvement of materials separation accuracy by superimposition of electric fields

In this paper, the existing techniques of electrochemical dimensional machining are considered. The use of an additional current-conducting template makes it possible to improve the accuracy of materials separation with the aid of the electric field superimposed.     

A technique for calculating large deflections of nonshallow elastoplastic shells of revolution under nonaxisymmetric loading

A technique for calculating the geometrically and physically nonlinear stress strain state of nonshallow shells of revolution under the nonaxisymmetric wind-like loading is proposed. The calculation results for a semispherical shell with the central hole and rigidly fixed edges depending on the loading nonaxisymmetry, material characteristics and thickness are presented. We demonstrate not only quantitative but also qualitative influence of taking into account the factor of joint nonlinearity on the process of shell deformation.     

Fractal assessment of microaccelerations at weak damping of natural oscillation in spacecraft elastic elements. II

Making use of the Weierstrass-Mandelbrot fractal function, some problems connected with the adequate assessment of microaccelerations aboard a spacecraft are considered. The ranges of values for the function parameters that make it possible to simulate the quasi-static component of microaccelerations are also determined.     

Ballistics of a nonfragmenting meteor body with allowance made for mass outflow in the non-isothermal atmosphere. I

The paper is devoted to studying the motion of meteor bodies with mass outflow in a planet’s atmosphere, taking into account the non-isothermal character of the latter. Analytical solutions are obtained at the constant parameter of mass outflow in the model of a nonfragmenting meteoroid. A theoretical analysis of the derived regularities of the ballistics of such bodies is presented.     

Theoretical fundamentals for constructing an integrated safety system of airborne ergatic complex operation

The initial statements are formulated and a technique is considered to solve a problem of providing trouble-free airborne ergatic complex (AEC) operation under the action of external disturbances, equipment failure, pilot’s errors and other unfavorable factors.     

Spacecraft “Foton-M” in-flight thermal conditions

The problem of thermal conditions aboard the “Foton-M” spacecraft during its orbital flight is under consideration in this paper. The problem is very acute for performing microgravity experiments onboard of the orbital platform, because on one hand, many experiments need a definite temperature range to be performed, and on the other hand all electrical devices aboard radiate heat. To avoid uncontrolled heating of the environment special heat exchangers are used. To transport heat from different places of the capsule to heat exchanger special fans are installed given definite orientation. All the heat exchange facilities should be designed in advance being adjusted to current capsule loading and heat radiation by equipment. Thus special tools are needed predicting the capsule thermal conditions being function of equipment placement.The present paper introduces a new developed prognostic mathematical model able to forecast temperature distribution inside the capsule with account of fan induced air flows, thermal irradiation by scientific equipment and heat losses due to cooling system.