MHD Simulations of the Dynamics of Sharp Disturbances of the Interplanetary Medium and Comparison with Spacecraft Observations

One-dimensional MHD simulations of solitary sharp and strong disturbances (impulses) of the interplanetary magnetic field and plasma of the homogeneous solar wind were performed. The characteristics of a disturbance of this type, recorded onboard the WIND spacecraft (SC) rather far from the Earth, were taken as initial conditions. The results of numerical experiments simulating the evolution of this disturbance in the moving interplanetary plasma, whose parameters correspond to observations of the WIND and INTERBALL-1 SC, show the efficiency of the computer code developed with the special purpose of investigating low-frequency wave events in the space environment. The calculated characteristics of the impulse resulting from the evolution are in good agreement with parameters of the disturbance recorded by the INTERBALL-1 SC closer to the Earth. In particular, the impulse expands due to imbalance of thermal and magnetic pressures, but keeps its abrupt boundaries. It was demonstrated that stable plasma objects, corresponding to stationary MHD solutions, could really exist in the solar wind plasma for a long time.     

深空通信文件传输协议的交织技术研究

引入喷泉编码技术应用于深空通信,对CCSDS文件传输协议进行改进,提出了一种针对深空环境长时延、高误码率、丢包率大和链路易中断等特点的基于数据包交织的文件传输协议。根据深空通信文件传输的业务需要设计了两种不同的级别概率分布,接收端只需要接收到一定数量的数据包,就能够恢复出整个原始信息,无需或需要很少反馈确认信息。仿真验证交织技术能够简化传输协议,减少文件传输时延,增大系统的吞吐量并保证通信的有效性。
     

Physics of Solar Prominences: I—Spectral Diagnostics and Non-LTE Modelling

This review paper outlines background information and covers recent advances made via the analysis of spectra and images of prominence plasma and the increased sophistication of non-LTE (i.e. when there is a departure from Local Thermodynamic Equilibrium) radiative transfer models. We first describe the spectral inversion techniques that have been used to infer the plasma parameters important for the general properties of the prominence plasma in both its cool core and the hotter prominence-corona transition region. We also review studies devoted to the observation of bulk motions of the prominence plasma and to the determination of prominence mass. However, a simple inversion of spectroscopic data usually fails when the lines become optically thick at certain wavelengths. Therefore, complex non-LTE models become necessary. We thus present the basics of non-LTE radiative transfer theory and the associated multi-level radiative transfer problems. The main results of one- and two-dimensional models of the prominences and their fine-structures are presented. We then discuss the energy balance in various prominence models. Finally, we outline the outstanding observational and theoretical questions, and the directions for future progress in our understanding of solar prominences.     

Flight efficiency of a pulsejet

Problems of the pulsejet flight efficiency dependence on the system parameter periodicity type are considered.     

Exact analytical solutions of a nonlinear nonstationary inverse problem of heat conduction for a body with low heat conduction coefficient

The analytical solution of a nonlinear nonstationary inverse problem of heat conduction for a bodies with low heat conduction coefficients of one-dimensional geometry is presented. The solutions obtained make it possible to restore the boundary conditions rather exactly using the results of heat flux measurements.     

Conditions for exciting the maximal gas vibration amplitude in a combustion chamber of the Helmholtz resonator type

In this paper, we present the results of calculating conditions for gas vibration excitement, sound pressure frequency and level as a function of mixture composition, geometric burner parameters and the resonator throat with constant capacity. We estimate in quantity the parameters influencing a vibration combustion process in the Helmholtz resonator with the inlet multichannel burner which result in the maximum possible gas vibration amplitude value.     

Variation of aircraft GTE turbine disks cyclic life depending on operational factors

Influence of the free air temperature during aircraft takeoff and engine operating time upon the cyclic life of an aircraft GTE turbine disk made from the heat-resistance deformable nickel-base alloy is analyzed and the variation of engine operating parameters in the process of service is taken into account.     

Analysis and parametric synthesis of the air ion counter measurement channel with impulse signal pickup from the aspiration chamber

The measurement channel of the air ion counter with impulse signal pickup from the aspiration chamber is considered. Peculiarities of its functional parts operation are analyzed and restrictions imposed on their parameters are stated. A technique is proposed and a set of equations that allows determining design parameters of the functional counter parts is presented.     

Fatigue life of a plate with an arbitrary-shaped concentrator under low-cycle plane loading

A technique and an algorithm for calculating fatigue life of a plate with a concentrator under complex loading in the low-cycle fatigue region are presented and the life of the plate with different shape concentrators is considered. The local stress strain state is investigated in the framework of plane loading using the finite element method with the aid of the MSC NASTRAN software and the life is evaluated with the use of an integral criterion of the concentrator contour loaded-up condition.     

Choice of optimal parameters of a gasodynamic temperature stratification process in the supersonic gas flow

The results of design analysis of the different factor influence on the gasodynamic temperature flow stratification efficiency in the Leont’ev tube are presented. It is justified that the temperature stratification efficiency can be increased at the expense of using longitudinal ribs on the heat exchange surface in the subsonic flow path, and the parameters determining the process can be optimized.