Home – Home – Jornals – Avtometriya 2020 number 3

The delay in detecting the position and shape of the plasma confined by a tokamak increases plasma instability and decreases the accuracy of plasma control in the tokamak. In this article, two techniques called periodogram and cross-spectral analysis are used to provide a quantitative approach for computing the time delay between the data obtained by two different coils from one source (plasma fluctuations) in the IR-T1 tokamak. After performing the Fourier transform of the data, the periodogram, square coherency, and phase diagram are plotted in terms of frequency in three different time intervals. In the time interval 29000 < τ < 30000 µ, where the plasma current is almost constant, the average phase shift between the frequency components of the data is obtained by using the phase spectrum analysis. The time delay between the data for the Rogowski and Mirnov coils is observed at the frequency of the highest coherency: τ_d = 1,831 µ.

Two algorithms for determining the coordinates of optical vortices are considered. In one of them, the vortex position is found from the branching of interference fringes, and in the second algorithm, by processing the distribution of gradients of the wave front. It is shown that both algorithms allow recording coordinates with high accuracy; in addition, it is possible to determine displacements of singular points resulting from radiation diffraction Keywords: optical vortices, branch points of interference fringes, local inclinations, Shack-Hartmann sensor

A control algorithm based on required differential equations in terms of deviations is proposed for solving the problem of tracking the desired trajectory in terms of the target position. Route planning is performed on the basis of the authors' method of calculating a plane trajectory consisting of oriented segments of straight lines connected by clothoids. Hardware and software for the automatic flight control are presented. The workability of the control system in the presence of measurement noise and external disturbances is confirmed by results of experiments on indoor quadrotor flight control

A method of setting the vertical by monitoring the measuring beam flare displacement in absolute laser ballistic gravimeters is described. The method is based on video recording of the displacement trajectory of a measuring beam reflected from a corner reflector during free-fall of the body. The magnitude and angle of the measuring beam deflection from the vertical are determined by frame-by-frame processing of the captured video sequence. An experimental verification of the method has shown that the error in setting the vertical is less than 3 • 10^-5 rad

This paper presents the results of numerical studies of the influence of rounding errors on the statistics distribution of statistical hypothesis testing criteria. The effect of rounding on the distribution of statistics of various goodness-of-fit test and homogeneity tests is examined. It is shown that if the rounding errors in analyzed samples are commensurable with the standard deviation of measurement errors, the distributions of test statistics can vary significantly. Under such conditions, the application of tests in data processing systems using classic results can lead to wrong conclusions. Recommendations to solve this problem are proposed

A mathematical model is considered, which allows one to estimate the root-mean-square deviation of beat noise arising in photodetecting of sub-carrier channel signals with QPSK and M-QAM modulation formats. Based on the theory and simulation results, a formula is derived for calculating the spectral distribution of beat noise as a function of the number of signals and the number of modulation formats used

The estimation of the scale parameter of a generalized Weibull probability density function is considered an analyzed by the minimum conditional risk criterion. Optimal estimates are obtained for the envelope intensity of signals reflected from extended objects provided that the intervals in the motion of these objects are independent of random variables. The above estimates are compared with the best unbiased estimate for various loss functions. It is shown that the risk convergence of the best unbiased estimate with the risk of an optimal estimate for the loss function equal to the error modulus is faster than the quadratic loss function. It is noted that optimal estimates for the invariant and power-law loss functions coincide. The lower and upper ε-confidence boundaries are obtained, and conditions under which these estimates correspond to estimates of the Weibull distribution parameter are determined

A method for describing and evaluating the state of a multidimensional dynamic object has been developed, which includes a numerical and analytical representation of the general solution of the differential equation for the dynamic object and its measured output, taking into account the range of admissibility of time values and the initial condition, as well as the uncertainty parameters on the right side of the equation. The required quality of representation is achieved using a family of high-precision reference integral curves (of necessary volume) constructed in advance and the principle of smooth dependence of the solution and measured coordinates in a given admissibility region for a wide class of dynamic objects. The error of the method is estimated, and recommendations for choosing its main parameters are given

In problems of automatic threshold image segmentation by brightness, the important questions are those about the number of brightness classes and, as a result, the required number of thresholds. A solution to the problem of estimating the number of classes in an image is often based on representing its distribution as a mixture of distributions of brightness classes. It is known that this problem (splitting the mixture) has a solution only for certain types of distributions, and, if the distributions of brightness classes are unknown, difficulties arise in its application. In this paper, a nonparametric method for determining the number of classes is presented, based on rank histograms and using the property of local spatial grouping of elements of each brightness class in an image. Comparing the proposed method with various criteria for estimating the number of classes in images shows that the method under consideration is effective

A method of guiding of a solar telescope with a high spatial resolution and an angular field of vision smaller than the angular size of the Solar disk with the use of an auxiliary guiding telescope whose field of vision covers the entire Solar disk and its vicinity is analyzed. Requirements to the guiding telescope resolution, guiding modes, and structural scheme of the guiding process are considered.

An experimental testbed and its automation for studying a heat generator based on Couette -Taylor flows between independently rotating multicylinder rotors is described. The flow structure is investigated using a technique for analyzing the pulsation spectra of the angular moment of resistance to rotation of the heat generator rotors. Methods for recording the generated heat power and studying the frequency characteristics of the flow inhomogeneities in a fluid located in cylindrical slot spaces with moving walls are presented. The developed equipment and measurement techniques make it possible to obtain experimental data on the influence of the heat generator operating modes and the working fluid parameters on the heat energy generation process

The possibility of developing a complex of spasers inside artificially created closed membrane shells (liposomes) is experimentally investigated. Localization of these complexes inside liposomes is confirmed using a scanning confocal microscope. It is demonstrated that, in this case, the spasers retain their performance. As shown by the results, encapsulating spasers into liposomes may turn out to be effective agents of theranostics

This paper describes studies of various schemes for implementing simultaneous mode synchronization and Q-switching of a resonator using a spherical mirror and an acousto-optic modulator (the SMAOM method) of a traveling wave in Nd:YAG laser. The time and energy output characteristics of diode-pumped Nd:YAG laser with SMAOM are presented along with the obtained high-power picosecond tunable radiation in a range of ~620 nm on the basis of cascade frequency conversion of a superluminescent parametric oscillator pumped by such a laser