This paper investigates the spatial distributions of electrical current which flows inside the plasma stream generated by a magnetoplasma compressor (MPC). Two different modes of MPC operation with different gas supply scenarios have been applied in the experiments presented here. The first is the operation mode with a pulse injection of xenon into the interelectrode space, and the second is the operation mode with residual helium in the chamber and local injection of xenon directly into the compression zone. The maximum value of the electric current observed outside the MPC channel is 15 ÷ 20% of the total discharge current. Electric current vortices were discovered in the plasma stream. The amplitude of the current in the vortices reaches 50% of the total discharge current. The maximum EUV radiation power was measured in the mode of MPC operation with local xenon injection. Power in the wave range 12.2 ÷ 15.8 nm achieves up to 16 ÷ 18 kW.
Climate change and shrinking of the Aral Sea have significantly affected the region’s temperature variations. Observed interannual changes in Uzbekistan’s air temperature compared to the duration of synoptic weather types (SWT) in Middle Asia were analyzed. Nonparametric Mann–Kendall statistical test and climate trends coefficients were used to identify trend characteristics of observed temperature from 1961–2016 to the baseline period of 1961–1990. The results showed increasing temperature trends average to 1 °C in warm and cold half years over Uzbekistan. The 1991–2016 decadal temperature trend ranged from 0.25 °C/decade in the northwest to 0.52 °C/decade in the center, especially pronounced in the oasis and Aral Sea zones. There were also significant changes in the structure of regional SWT. The main difference in the structure of SWT in Middle Asia relative to the baseline period was expressed in a decrease of cold mass invasion duration from 113.4 to 76.1 days and an increase in low-gradient baric field duration from 65.8 to 134.6 days. The process of anthropogenic warming, which began in Uzbekistan in the 1960s of the twentieth century, has accelerated from the mid-1970s with a higher mean annual air temperature than the baseline period’s climate normals (1961–1990) and is associated with changes in the regional SWT over Middle Asia.
In this article, the method to estimate the range to the beacon in passive search and rescue systems is proposed. The range to the beacon is determined by applying a set of Kalman filters to the bearing measurements with different hypotheses of the beacon motion and subsequent selection of the hypothesis with the minimum sum of residual errors in target range estimation. The expressions for the expectation and standard deviation of the prediction errors are derived and the probability of selection the correct hypothesis is given. The proposed method allows to evaluate the measurement time, required to determine the range to the beacon with probability 0.9…0.95, which agrees well with statistical analysis of multiple data sets.
The method of adaptive nonlinear matching of dynamic ranges of radar signal and imaging device is proposed. The method is intended for use in the onboard remote sensing complexes during formation of radar images of the earth's surface. The method is aimed at increasing the visibility of small objects on the background of the underlying surface in order to simplify the procedures for their detection and identification. The computational complexity of the proposed algorithm makes it possible to use it in real time.
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