Home – Home – Jornals – Avtometriya 2021 number 3

To improve the operational characteristics of multi-element photodetectors with spatially nonuniform sensitivity, sensitivity equalization based on their calibration is applied which must be repeated from time to time during detector operation due to the temporal drift of its parameters. Specialists are interested in methods of calibration and correction that do not require the use of standard light sources for illumination of the photodetector. The proposed method for evaluating and correcting the nonuniform sensitivity of a scanning photodetector array (PDA) is focused on attenuating the influence of this interference during interframe processing and is based on the analysis of a pair of images formed in the process of mutual displacement of the PDA and the recorded scene. With a known displacement of the images along the columns located in the image overlap zone, an underdetermined system of equations is constructed, which is solved by the least squares method (LSM). A method for correcting the solution error caused by the underdetermination of the system is presented. A numerical experiment has confirmed the effectiveness of the method in application to interframe background suppression and detection of moving small-sized objects.

The method of active jamming suppression based on differences of space-time signals and interferences of spectral characteristics in radiotechnical systems with antenna arrays is proposed. An expression for the spectrum of the space-time signal in antenna arrays is derived. The results of experimental studying of the developed algorithm for different numbers of active jamming sources is presented.

Problems of structural optimization of networks for various purposes are studied in order to obtain the most reliable topologies under conditions of random failures of network elements. Several indicators are considered as reliability, while nodes of the network are subject to failures. To accelerate the search for optimal solutions, an approach is used with a cumulative updating of the network reliability bounds, which makes it possible to cut off insufficiently reliable variants at the early stages. Within the framework of this approach, we propose to evaluate the reliability by the trends for known reliable variants at intermediate stages of optimization. The results of numerical experiments are presented.

The problem of determining the distance from an arbitrary point to the center of an interference band with a known profile from data distorted by random noise is posed. The developed algorithm uses the Wiener-Kolmogorov filtering at the final stage of obtaining the estimate. Numerical simulation shows that the average error of the estimate calculated by the proposed method is smaller by 50-75% than that obtained under the assumption of no noise. The results of the experimental data processing also confirm the effectiveness of the proposed method.

The paper focuses on the methods of dynamic control of nuclear fuel microobjects, both designed and approbated. These methods are based on the reconstruction of spatial geometric properties of microobjects with the usage of the outlines of two-dimensional shadow projections. To describe the microobject dimensions, the overall dimensions and average diameter are taken into consideration. To describe the shape factor, the non-sphericity coefficient is defined as the ratio of the maximum to the minimum overall dimension of an object. The metrological characteristics of the designed control methods are considered.

In this paper, we consider the possibility of using reinforcement learning systems for solving control problems under conditions of a lack of a priori information about the control object. The paper presents a solution to the problem of training the system by the Deep Deterministic Policy Gradient method for objects with a transport delay, as well as a comparison of the efficiency of the proposed solution with the classical method based on PID control, calculated using extended amplitude-phase-frequency characteristics and the Ziegler-Nichols method.

The paper justifies the danger of the contact between the fan impeller blades and the gas turbine engine (GTE) case, determines the factors affecting the radial clearance in flight, identifies the main causes of the contact, analyzes the current means of determining the radial clearance of the GTE, and proposes a technique for detecting the contact between the GTE fan rotor blades and its case in flight based on complex processing of the signals of the fan body vibration and pressure pulsation detectors behind the fan. Implementing an identification technique based on processing of vibration and pressure pulsation signals will improve flight safety, especially for prototype GTEs at the first flight test stages, without the need for additional preparation and installation of complex clearance control systems. This technique can be used to identify the contact when the radial clearance is extremely reduced, which will allow for the timely selection of the mode setback (where possible, at the stage of flight it occurred) to prevent significant damage caused by the contact.

A method of computer simulation of a network device using its digital emulator and creating a digital environment for generating network traffic through it is presented. The emulated objects are represented by a set of functional and interface threads interacting through virtual communication lines, which are shared memory areas. This approach allows one to minimize the time spent on transferring packets between virtual devices of the emulated system and focus attention on the algorithmic component of the simulated device. As an illustration of the method, a computer simulation of the operation of a filtering device for the HTTP protocol as part of an information Web-system is demonstrated.

Time interleaved analog to digital converters (TIADCs) are used when high sampling rates are required. However, TIADCs have offsets such as the sampling time, gain, dc, and phase offsets. Due to these offsets, the reconstructed signal from TIADCs is erroneous. Hence, these offsets should be estimated and then corrected. The proposed work focuses on the estimation and correction of the offsets. For the estimation of offsets, the differential evolution optimization algorithm is used, and the correction is applied using the estimated offsets. The estimation is evaluated by finding the bit error rate (BER) and the signal to noise and distortion ratio (SNDR). The estimation and correction are implemented for 7 and 8-channel TIADCs in an orthogonal frequency division multiplexing (OFDM) system with 4-QPSK modulation. The technique is evaluated by applying monotonic sinusoidal and image signals to the OFDM system.

The value of the limiting specific power of capacitive electrostatic motors with a metal - thin-film ferroelectric structure with a large specific capacity - nanogap - movable electrode is determined. The maximum possible frequency of power conversion for such motors is estimated. Using the previously determined value of the limiting energy density for energy converters based on such structures, it is shown that the limiting power reaches 5· 10⁸ W / kg and exceeds the power of inductive motors by 5 orders of magnitude.

The study is devoted to the development and research of a model of a pulse laser location system without the use of an image intensifier as an external shutter. The system is designed to detect retroreflective objects, including optical and optoelectronic surveillance devices. A description of the hardware and capabilities of the created special software is presented. The results of measuring the dependences of the signal value on the angle of rotation of the retroreflective objects relative to the direction of the optical axis of the pulse laser location system, on the distance to the object, and on the value of the aperture of its lens are presented. The parameters of retroreflection of typical video recording devices in real conditions are determined experimentally. A method is proposed and demonstrated for calculating the maximum detection range of retroreflective objects in the presence of information about their retroreflective index by measuring the informative signal at deliberately shorter ranges with an increased degree of diaphragming.

Specific features of the formation of images of an asymmetric edge of a 3D-object with an absolutely reflective internal surface are analytically investigated from the viewpoint of dimensional inspection. Formulas are derived for calculating fields in images of object faces in ideal and diffraction-limited systems depending on the magnitude of the object bevel с , phase shift ϕ of the wave reflected from the inner surface of the object, and angular aperture 2θ₀ of the coherent projecting optical system. For metallic 3D-objects (ϕ = π) the value of the field in the image of the back face at a point x₁ = c, corresponding to the position of its boundary is found to be negligible if the depth of focus of the system is much smaller than the object thickness. For object bevels с much smaller than the size of the Fresnel zone δd ~ √λd(λ is the light wavelength, and d is the object thickness) and greater than the depth of focus ∆z, the displacement of the intensity profile in the image of the front face is proportional to c/δd and depends on the angle ϕ. With large bevels, when c >> δd and Δz >> d, the displacement of the front face boundary is inversely proportional to c/δd. These displacements can lead to systematic errors of measuring the boundary positions of the 3D-object and should be taken into account in precision dimensional inspection.

The reflection of infrared radiation from diaphragm coatings in photodetector devices: black polymer paint, anodic oxide, etched kovar, suspension of graphite or titanium oxide in cryogen-resistant varnish, and others are investigated. The spectra and integral reflection coefficients of the diaphragm coatings in the wavelength range of 2÷14 microns at the radiation incidence angles of 15 and 45 ^◦ are elucidated. The levels of reflected infrared radiation in the spectral ranges of 3.4-4.8 and 7.5-13.5 microns are also studied in a wide range of angles from 0 to 80° for a radiation incidence angle of about 15°. According to the research results the lowest level of infrared radiation reflection is provided by the coating of a graphite suspension in a cryogen-resistant varnish (developed at the Novosibirsk Branch of the Institute of Semiconductor Physics of the Siberian Branch of the Russian Academy of Sciences “Technological Design Institute of Applied Microelectronics”, Novosibirsk). The integral reflection coefficients for this coating are 3.98% (in the spectral range of 3-5 microns) and 5.69% (in the range of 8-12 microns).

A review of results obtained in recent years by the authors in studying the stability of flows with separation of the laminar boundary layer under the condition of flow modulation in space and time is presented. These results provide an idea about the influence of periodic inhomogeneities of the separation region on the development of its hydrodynamic disturbances and the transition to the turbulent state near the body surface in a low-velocity air flow.

It is revealed that the local equilibrium approximation (algebraic parametrization of triple correlations of turbulent fluctuations of a vertical velocity component) in the problem of a plane momentumless turbulent wake is a differential constraint for a third-order closure model. The results of numerical experiments that confirm the feasibility of the used known algebraic parametrization of this third-order correlation moment are presented.

Implicit finite-volume predictor-corrector algorithms based on the splitting method are proposed for the numerical solution of the Navier-Stokes equations written in integral form for a compressible gas, and the properties of these algorithms are investigated. An economical algorithm for splitting equations into physical processes and spatial variables is considered. Numerical solutions of two-dimensional and spatial fluid dynamics problems are determined and compared with the known computational results. It can be concluded on the basis of the estimates obtained and calculations performed that the proposed algorithms are effective.

Mathematical methods are developed to describe helium sorption by microspheres with a certain dispersion distribution. An analytical solution of the problem is derived and applied to expand the experimental dependences of the degree of helium absorption by microspheres on time into harmonics. As a result, the time characteristics of the sorption process can be analyzed.

Results of numerical simulations of fracture of nanocrystals of the TiAl3 intermetallic compound by the molecular dynamics method are reported. The TiAl3 nanocrystals are subjected to uniaxial tension in a wide range of temperatures (300-1200 K). It is demonstrated that tension of nanocrystals of the TiAl3 intermetallic compound heated approximately up to 1000 K first leads to a phase transition from the crystalline to liquid state, followed by their fracture. Fracture of a heated TiAl3 nanowire is preceded by deformation in the superplasticity regime.

The influence of a quenching air jet on physical and chemical properties and morphology of titanium dioxide, silicon dioxide, and TiO2-SiO2 composite particles synthesized by the single-stage chloride method in a flow-type plasma-chemical reactor is studied. The results of the simulations and analysis of the specimens show that the physical and chemical properties of the powder and the morphology of its particles can be controlled. It is demonstrated that the results of mathematical simulations of the synthesis of TiO2 and SiO2 particles agree well with the experimental data obtained in the study.

The linear and nonlinear stability of two-layer Poiseuille flow in a horizontal channel is considered, and the stability of this flow is compared with the stability of the same flow in a vertical channel. In the first step, the Navier-Stokes equations in both phases are linearized, and the dynamics of periodic perturbations is determined by solving the spectral problem in a wide range of the Reynolds number of the liquid and the gas velocity. The neutral and fastest growing perturbations of the unstable mode are calculated. In the second step, nonlinear wave modes of Poiseuille flow in the horizontal channel are calculated using the full Navier-Stokes equations for both fluids.

The dynamics of death of cardiac muscle cells during the acute phase of myocardial infarction has been studied numerically. The problem is considered in the local and spatially distributed formulations. The adequacy of the mathematical model is confirmed by the quantitatively agreement between the results of numerical solution of the problem and experimental data. The adopted models were used to investigate the trigger mechanism of transition from a favorable scenario for the development of an acute myocardial infarction to a scenario characterized by a rapid increase in the level of myocardial damage on the third - fifth day of myocardial infarction. For these scenarios of the development of a myocardial infarction, the process of demarcation inflammation has been investigated. It has been shown that the results of studies, including evaluations of the effectiveness of cytokine anti-inflammatory therapeutic strategies are consistent with available data of laboratory studies.

Melting of a layer of ice with air bubbles exposed to an artificial thermal radiation source is studied by mathematical modeling within the framework of the one-phase Stefan problem. The radiative part of the problem of radiative-conductive heat transfer in the ice layer is solved numerically by a modified average flux method taking into account the volumetric absorption and scattering of radiation in the medium and the selectivity of the radiation. The anisotropic scattering of radiation by air bubbles is taken into account using a transport approximation. It is shown that the calculation results are in satisfactory agreement with experimental data.

Models of poroelasticity and discrete cracks serve as a basis for a numerical study of filtration in deformable fractured porous media. The influence of the stress-strain state of a medium on its filtration properties is considered. Oil displacement from fractured formations is investigated. It is shown that compressive stresses have a significant impact on the efficiency of oil displacement. Calculations are carried out for three versions of randomly developed systems of cracks with different degrees of coupling.

A computational and experimental analysis of the properties and fundamental features of a turbulent boundary layer on an elongated axisymmetric body of revolution under conditions of an incompressible flow around it at the Reynolds number Re_L = 4.33 x 10⁶ is carried out. It is shown that the experimental values of the local and integral parameters of the boundary layer on the body of revolution are in reasonable agreement with the results of a numerical calculation performed by solving the Reynolds-averaged Navier-Stokes equations using the low-Reynolds version of the k-w SST turbulence model. The data obtained indicate the need for careful contouring of the aft part of the body of revolution in order to minimize losses caused by the bottom drag of the aft end.

The propagation of a short compression pulse in heterogeneous targets containing ceramic inclusions of various sizes is studied numerically. The case of a heterogeneous material with inclusions of macroscopic size is considered. It is shown that during propagation in all targets, the initial shape of the shock pulse evolves to a shape corresponding to an elastic stress-strain state in which its amplitude and length do not depend on the distance traveled. It is found that for heterogeneous materials with large inclusions, the rate of decrease in pulse amplitude is greater than for heterogeneous materials with small inclusions.

Adaptation of a mathematical model of gas diffusion combustion for different flow rates of CO-H₂ and a constant coal flow rate is carried out. It is shown that the results of calculating the main characteristics of the flame are in satisfactory agreement with experimental data and can be used to determine the structure of pulverized coal-gas flow, gas composition, particle and gas temperature, carbon combustion efficiency, etc. The proposed model is suitable for analyzing the stability of coal-gas flame and the transient processes accompanying changes in the mode of supply of the fuel-oxidizer medium

This paper presents a study of the atomization and combustion of coal-water slurry fuel sprayed by a pneumatic nozzle based on the use of wall and cumulative jets and the Coanda effect. The droplet size distribution of coal-water fuel slurry at the nozzle outlet was measured by shadow photography. In the region of fuel ignition, the characteristic droplet size in the flow is 20 μm and the coal particle size is 100 μm. The results of experiments on an uncooled firing stand with an uncooled 5 MW furnace showed the possibility of efficient co-combustion of coal-water slurry fuel and pulverized coal using the developed burner.

A case of two-dimensional motion of thermal waters under the action of two wells comprising a spaced dipole is investigated on the basis of a reservoir model in the form of a heterogeneous structure consisting of disjoint continua, one of which is embedded into the other. Calculations are performed for specific physical parameters of the reservoir and active wells.

A method is proposed to improve the aerodynamic performance of small-sized flying vehicles. The method is based on fundamental gas-dynamic phenomena, such as local separation of the boundary layer accompanied by the formation of the so-called separation bubbles, separation of the turbulent boundary layer, and flow shedding from the leading edge of the airfoil, which alter the entire flow structure around the body. Publications where the relationship of these phenomena is established and those that describe a control method eliminating the adverse consequences of flow separation with the use of a wavy surface of the airfoil are reviewed. The method is simple in implementation and offers many prospects. The area of its applicability are determined, and criteria of optimizing the wavy surface of the airfoil for particular operation conditions are provided. Results of investigations are reported, which show that the use of a wavy surface of wings or blades of flying vehicles can improve their aerodynamic characteristics. Various structural elements of the boundary layer are noted, such as local separation bubbles or a general separation region, and criteria of their emergence are given, which assists in verification of numerical experiments.

The accuracy of numerical calculations of the dynamics of vortex filaments is estimated via the truncation method using the example of the motion of helical vortices. In the case of helical vortices with uniform vorticity distribution in Rankine core, there are two more analytical approaches to solving the problem. These approaches are used to determine the minimum admissible distance between vortex filaments or their elements to ensure the accuracy of calculations when using the truncation method. There is an established error that occurs in the calculations based on the truncation method in the case of convergence of the windings of a helical vortex.

We identify a number of Sextus Empiricus’ skeptical arguments that use assumptions about a holistic nature of the systems, which Sextus considers. All these systems contain mental objects. We construct a general formulation for the holistic assumptions used by Sextus, as well as reveal the specifics of the systems considered by Sextus. We point out the premises which are basic both to Sextus’ approach and modern versions of mental holism (M. Esfeld, etc.). Our interpretation uses the assumption that the intentional objects in Sextus’ arguments under consideration are internal, or mental, objects. In our formalization of Sextus’ statements, we use the notation of propositional attitudes reports with doxastic operators. We also use the assumption that the internal intentional object is an abstract object that encodes its characteristics - in accordance with E. Zalta’s approach to abstract objects.

The article states that the peculiarity of the objective-idealistic component of Descartes' philosophy lied in its theological character, represented by the Christian doctrine. In this component, the subject of attention are two aspects highlighted by Descartes himself - the one which can be perceived by the human mind and the one which is beyond perception. Accordingly, even the article identifies the first as irrationalistic and the second as pretending to be rationalistic. But further thorough analysis of the aspects of the content of Christian ideas about God, which Descartes considered to be accessible to the human mind, revealed their real irrationality, which Descartes himself did not notice.

The article studies how I. Kant’s works influenced the development of concepts in analytical philosophy and considers the evolution of referential categories. It affirms the historical continuity of the ontological metaphysical bases of referential categories in the works of the analytical philosophers (W. Quine, P. Strawson), the independence of the relevant aspects from the epistemological orientation of Kantian philosophy, and the plura-lity of ways by which the lines of Kantianism spreads.

We propose a generalization of David Egan’s structural analogy between Heidegger’s Angst problem and Wittgenstein’s rule-following problem to the case of the problem of hinge propositions, considered by Wittgenstein in his work On certainty . In our view, Wittgenstein’s later philosophy contains the notion of authenticity: the language games as new correct uses of Wittgensteinian rules are authentic. We treat the analogy between Heidegger and Wittgenstein from the point of view of a contextual realism. We also indicate that there are substantial differences in the approaches of the two philosophers.

The article discusses the main characteristics and features of the abduction method, studies the possibilities of using abduction and hybrid combinations of abductive and inductive approaches in modern digital science. It is shown that the complex use of inductive, deductive and abductive methodologies provides greater interaction and synergy in the formulation of new hypotheses and the search for cause-and-effect relationships. It is argued that in digital science, abduction must take into account the quality of big data and the context of big data generation.

The problem of persistence is one of the central problems in modern analytic metaphysics. Nevertheless, little attention has been paid to this topic in the Russian literature. The article concentrates on explication of the main theoretical solutions available within the framework of three-dimensional ontologies of persistence in time. The author analyzes the problem of temporary intrinsics and the available strategies for solving this problem, viz indexicalism and adverbialism. Then, he considers the paradox of constitution. First, the paradox itself is explicated. Second, the identification of the problem that makes the constitutive paradox seem problematic is proposed. Third, two classes of solutions to the paradox are studied: pluralism and monism.

The lack of direct traces of significant anthropogenesis processes requires an appeal to the theory of evolution as well as to epistemology. Productive ideas of the Russian evolutionism make it possible to integrate the opposing directions: neo-Darwinism (synthetic theory of evolution) and the concepts of orthogenesis (or nomogenesis). The principle of multilevel selection is developed in many works where the analysis of selection processes is carried out at the individual, group, and species level. Main drivers of evolution take place not just in organisms and genes but in the interaction of living systems with environmental niches while consolidating the consequences in genetic structures. This basic principle allows to build a corresponding framework of systemic and functionalist concepts. Expanding the nomological scheme of the scientific explanation by K. Hempel it possible to include various indirect data into deductive logical forms. The universal hypothesis takes the form of ‘the provision principle’: a structure as a new sapient trait provides a care. If heterogeneous consequences of a hypothesis of this type are tested and occur to be true, they confirm it. The components of the empirical hypothesis are judgments about the initial conditions and effects: the appearance of a certain sapient trait in a particular period of the anthropogenesis. The combination of theoretical and logical-methodological approaches is used to analyze the morphological sapientization (from Australopithecus to Homo sapiens) and the evolution of language (from social conditions of verbal communication and first proto-words to successive stages of proto-language and full-fledged language development).

Information has many interpretations, but there are strong arguments in favor of the fact that this phenomenon is objective and serves as an indicator of the complexity of the system. One of the bases for classifying its types may be the hierarchy of levels of material organization. Modern society has moved on to the systematic use of mostly physical information. Biological information, which is represented by genetic, nervous, and other signaling processes in organism, also appears to have a physical (in particular electromagnetic) and chemical shell, but is not reduced to the latter, because it expresses the properties of self-preservation and adaptation that are emergent qualities of the living matter. On the other hand, physical information has formed the global information environment, that is the infosphere, which has begun to have biological (stressful, maladaptive) effects on humans. The dual key to managing biological information and overcoming these negative effects is the further deepening of bioknoledge and ecoknowledge, as well as its active conversion into appropriate technologies. In the future, it becomes possible to regulate the information flow of the highest biological level, i.e. the biosphere, as well as to transit to the directed evolution. Since the management of bioinformation processes can directly affect the vital aspects of human life, the development of its strong limiting regulators is expected. They will have both bioethical and biolegal bases and suggest a complex anthropological expertise.

The article argues that according to R. Rorty, the main drawback of the central concept of analytical philosophy - the analysis of meaning-is the lack of continuity of schools and generations. Rorty traces the intermittent development of the analytical movement from G. Frege and B. Russell to the Oxford School of Ordinary language, and then to W. Quine and S. Kripke. The synopsis of the change in the concepts of analysis is presented for Rorty by S. Soames’ final description of the history of analytical philosophy as a change in technical, highly specialized areas related to logic and logical semantics. Rorty believes that this loses the basic value of philosophy-an attempt to describe the relationship between theory and reality.