Vol 55, No 2 (2019)

The monochromator of the Kosmos synchrotron radiation metrology station is discussed. The results of testing the monochromator in the energy range 2000–6000 eV using Si (111) crystals are presented. A spectral resolution ΔE/E = 10⁻⁴ was obtained. A technique for checking the spectral purity of the monochromatic radiation is described. It is shown that the monochromator can be used for spectroscopic measurements in the indicated energy range.

This paper is a continuation of previous studies on the development of X-ray topo-tomography using laboratory equipment. The results on the spatial location of a single polygonal dislocation half-loop in a silicon single crystal were obtained as a result of testing the sensitivity of the X-ray topo-tomo diffractometer. A comparison was made with high-resolution experimental data obtained at the European synchrotron radiation facility (ESRF). The experimental procedure, software, and hardware for 3D reconstruction of the investigated single defect — a polygonal dislocation half-loop — are described.

For correct numerical interpretation of tomographic images, i.e., estimates of the attenuation coefficients of objects, it is important to obtain reconstruction of high quality, which depends directly on the methods of processing experimental data. Data processing flow begins with its preparation for the application of the reconstruction algorithm. The necessary part of data processing contains the subtraction of the black field, normalization considering empty data, and taking logarithm. This part is not sufficient for obtaining high-quality reconstruction when working with real data since it is not ideal. Real data include noise and distortions due to changes in the setup geometrical parameters during the experiment. We have analyzed two possible types of data distortions during experiment and suggested corrections for them. The first one corrects thermal shifts regarding beam decentralization, and the second eliminates the effect of the polychromatic nature of X-ray radiation on the results of tomographic reconstruction. These methods were tested with both real and synthetic data. Both synthetic and real experiments show that suggested methods improve the reconstruction quality. In real experiments, the level of agreement between the automatic parameter adjustment and experts is about 90%.

An intensely developing aspect of advanced microelectronics is microelectromechanical systems (MEMS). The present paper describes various issues associated with the development of a new MEMS clock generator capable of operating at gigahertz frequencies. The main features of generating and supporting forced oscillations of the moving electrode under the action of electrostatic forces are analyzed. A possibility of supporting such oscillations under conditions of high inertial g-loads (up to 10⁶g and more) is demonstrated. A mathematical model of a micro-oscillator is developed, and the basic regimes of its operation are described.

A combined method of object visualization based on analytical and scalar perturbation functions and three-dimensional textures with the use of graphics processing units is proposed. To display the terrain and the change in levels of detail, the same method as that for color textures is applied, and vertex shaders are used in the case of scattered light. A method of real-time visualization of volumetric clouds is described. For this purpose, it is proposed to form three-dimensional textures by means of pre-processing of the cloud structure and volume-oriented visualization.

The paper describes solving the problem of automatic verification of control software in cyber-physical systems created by means of process-oriented programming. A method based on plant simulators is proposed, and its implementation on the basis of the LabVIEW package and Reflex language translator is described.

A machine learning approach for prediction the characteristics of tonal noise formed in a foil flow is tested. Experimental data are used to construct and analyze the mathematical models of pressure amplitude regression and models of classification of regimes of high-level tonal noise coming from the dimensionless parameters of the flow. Different families of algorithms are considered: from linear models to artificial neural networks. It is shown that a gradient boosting model with a determination coefficient 95% is the most accurate for describing and predicting the spectral curves of acoustic pressure on the entire interval of values of amplitudes and characteristic frequencies.