Multi-criteria analysis of aircraft structures fracture

A novel modular multistep algorithm is proposed for multi-criteria analysis of fracture of aircraft structures with complex geometries. In order to evaluate the algorithm, the crack growth analysis is realized by the following three criteria, namely, the stress intensity factor, the strain energy release rate, and the J-integral. The algorithm implementation by the finite element method is considered and prospects of alternative implementation based on the meshfree methods are assigned.     

A concept of increasing efficiency for ramjet operation

The vortical mixing concept in the ramjet channel is analyzed. The results of simulating the gasodynamic scheme permit the concept of increasing efficiency for ramjet operation to be substantiated.     

寒冷地区农村建筑围护结构热工性能优化及经济性研究

农村建筑热工性能较差,采暖季能耗居高不下。本文通过Dest软件建立模型,对寒冷地区农村建筑不同围护结构下能耗情况进行模拟,并建立P1-P2经济分析模型,以全生命周期费用最小或者净现值最大确定合理的外墙保温层厚度及窗户类型。     

Numerical and Experimental Study of a Hybrid Segmented Air Bearing for an Aircraft Gas Turbine Engine

The bearing capacity of hybrid segmented bearings with different groove systems is compared. The research establishes that the system with a crescent groove has the best characteristics.     

Separation of the Galactic Cosmic Rays and Inner Earth Radiation Belt Contributions to the Daily Dose Onboard the International Space Station in 2005–2011

The DB-8 detectors of the ISS radiation monitoring system (RMS) have operated almost continuously onboard the ISS service module since August 2001 till December 2014. The RMS data obtained were used for the daily monitoring of the radiation environment aboard the station. This paper considers the technique of RMS data analysis that allows one to distinguish the contributions of galactic cosmic rays and the Earth’s inner radiation belt to the daily dose based on the dosimetry data obtained as a result of the station’s passage in areas of the highest geomagnetic latitudes. The paper presents the results of an analysis of the dosimetry data based on this technique for 2005–2011, as well as a comparison with similar results the authors obtained previously using the technique based on an analysis of the dosimetry data obtained during station passages in the area of the South Atlantic Anomaly.     

Application of small-size antennas for estimation of angles of arrival of HF signals scattered by ionospheric irregularities

A modification of the Doppler Interferometry Technique is suggested to enable estimating angles of arrival of comparatively broadband HF signals scattered by random irregularities of the ionospheric plasma with the use of small-size weakly directional antennas. The technique is based on the measurements of cross-spectra phases of the probe radiation recorded at least in three spatially separated points. The developed algorithm has been used to investigate the angular and frequency-time characteristics of HF signals propagating at frequencies above the maximum usable one (MUF) for the direct radio path Moscow-Kharkiv. The received signal spectra show presence of three families of spatial components attributed, respectively, to scattering by plasma irregularities near the middle point of the radio path, ground backscatter signals and scattering of the sounding signals by the intense plasma turbulence associated with auroral activations. It has been shown that the regions responsible for the formation of the third family components are located well inside the auroral oval. The drift velocity and direction of the auroral ionosphere plasma have been determined. The obtained estimates are consistent with the classical conception of the ionospheric plasma convection at high latitudes and do not contradict the results of investigations of the auroral ionosphere dynamics using the SuperDARN network.     

Method of determining the maximum permissible values for diagnostic signs of helicopter transmission units operational status

A method of determining the maximum permissible values for diagnostic signs, being an integral part of health and usage monitoring systems (HUMS) of the helicopter transmission units, has been developed based on a probabilistic approach.