SCIENCE & EDUCATION

This article deals with increase in accuracy of positional (photo-electric) laser measuring systems. Amplitude instability of laser radiation represents the most significant part of total measurement error. A method for introducing feedback on intensity of laser radiation into the structure of a laser measuring system was proposed; this feedback allows one to stabilize the measuring system parameters. Introduction of this feedback was provided by mounting an additional photoreceiver which registers the reflected laser beam; a signal from the photoreciever is used for correction of information received from the main measuring channel.

This paper considers a mathematical model for estimating resolution measuring properties of an aerialphotosystem developed on the basis of photosensitive devices with charge transfer. The proposed mathematical model which implements an analytical method for estimating resolving power of aerial photosystems based on the theory of linear optoelectronic system allows to obtain assessments of resolving power for various types of aerial photosystems with consideration for their conditions of use.

A study of aerial photosystems that are based on the photosensitive charge-transfer devices was carried out in order to determine the linearity of their units. To estimate the linearity of photosensitive charge-transfer devices the authors used results of a specially developed technique of physical research, which is based on the construction of light characteristics and verification of the superposition principle. It was shown that a photosensitive charge-transfer device is a linear unit within a certain range of brightness. Width of this range was determined by the introduction of the notion - light latitude of a photosensitive charge-transfer device.

The authors proposed and justified a new approach for predicting conditions of an aerospace survey in order to improve its effectiveness. This approach is based on the fact that information on optical characteristics of the atmosphere, the earth's surface brightness, spectral reflectance, as well as exposure parameters of shooting performed in the form of layers of the geographic information system, could be used for solving problems associated with planning an aerospace survey. The basic idea of this work lies in forming a high dynamic layer of the continuous phenomena of geo-information system; this high dynamics is caused by high dynamics of change in meteorological conditions.

This paper deals with a comparative analysis of algorithms for regenerating concentration of gases in complex multicomponent mixtures by means of multispectral laser measurements. Signal processing methods for complex multicomponent mixtures based on the Bayesian assessment of a solution and the projective method are described in this work. The results of the mathematical simulation show that usage of the Bayesian assessment for a solution of the laser gas analysis system of equations allows to solve a problem of regenerating concentration of gases for complex multicomponent mixtures with smaller errors than usage of the projective method. 

Defects in multilayer constructions made of composite polymeric material, for example, defects that occur when the material discontinuities, reduce their performance. Considering a high cost and complexity of manufacturing such products from polymeric composite materials, as well as a high cost of products in which these polymeric items are used, detection of defects during manufacture and exploitation of products appears to be a very crucial task. Therefore, creation and implementation of equipment and methods for reliable detection of defects within a large application domain is reasonable. This paper describes main principles and methods of complexation of information of multi-parameter nondestructive control with the purpose of increasing reliability of detection of defects in complex structures by the example of structures made of polymeric composite materials. The results of developing a method of complexation of nondestructive control methods addressing the formulated problems are presented in this work. These results are based on estimation of the telescoping effect and building a multi-dimensional analogue of the inverse probability method.

The purpose of this paper is to analyze possibilities and select laser sources for onboard laser ranging systems (LLS) of space vehicles designed to locate by a diffusely reflected signal and corner reflectors (CR). Characteristics of semiconductor, solid-state and fiber lasers were presented. Energy evaluation of range capability of onboard LLS in pulsed and continuous radiation modes using lasers of different types was conducted.  It was shown that increase in range capability of onboard LLS by a diffusely reflected signal up to 10 km was provided with the use of fiber lasers, and for the range capability of more than 10 km usage of solid-state lasers was required. Influence of corner reflector parameters on the range capability of LLS was estimated. The obtained results could be used in development of onboard LSS for innovative space vehicles.

The author proposes a method of fitting the Siacci air resistance law which was practically approved to the law of 1943. This law is widely used in the Russian Federation for computing parameters of trajectories of projectiles but doesn’t have an analytic description up until today. In this work a corrective multiplier for the Siacci function was introduced; this factor represents analytical approximation of a sequence of discrete compensation factors in the form of a continuous dependence on the projectile speed (Mach number). As a result, computation of the trajectory parameters with the use of a PC is simplified. An example of using the approximation is also provided.

In order to determine the initial stage of the interacting process between an explosive item and an obstruction, which is the most important for operation of contact target sensors (CTS), the author proposes two approaches to approximation of initial force characteristic of an obstruction; they were a piecewise function and a dependence of the explosive item’s cross sectional area on displacement. In this process, empirical formulas for the full path of an explosive item’s punching-in into an obstruction were used along with some experimentally derived facts. An example of calculating the response of the cluster ammunition element’s CTS was given. The author considers a possibility of using an integrating type of CTS as a means of measuring the explosive item’s speed after piercing an obstruction and filtering the imposed oscillations.

The authors conducted a study based on the use of such methods as IR-spectral ellipsometry and Raman spectroscopy of protective diamond-like coatings (DLC) which are applied on amide-imide resin samples. Within the framework of this investigation the ratio of sp2/sp3 bonds, optical constants, resistivity and thickness of protective diamond-like coatings were determined. The obtained data may appear useful when developing operating practices of coating DLC, as well as determining the relationship between physical and chemical characteristics of coatings (chemical composition, thickness, etc.) and their functional properties (barrier properties against negative space factors).

This article presents a description of a functional principle, a structural scheme and an operation of the technological photometrical equipment designed to determine the time of origin of thermal decomposition and development in polymer composite materials; this decomposition appears during machining of such materials in modes with high temperatures in the area of chip formation and represents one of the major defects of machined surfaces. The proposed equipment developed in Bauman MSTU allows to determine the value of thermal destruction during machining without harming product integrity. This equipment could be used for studying influence of machining conditions on the value of decomposition, for in-process detection and for adaptive control of machining in order to provide the required manufacturing quality.

This paper presents results of a comparative analysis of input signal power of laser systems for target location and ultraviolet vision. It was shown that the spectral band of 300-400 nm is promising for laser systems of the ultraviolet range operating in the earth atmosphere. Within the spectral band of 300-400 nm coefficients of ground reflection have greater values, and coefficients of atmospheric attenuation have smaller values then they do within the spectral band of 200-300 nm. The closer the wavelength gets to the value of 300 nm, the less background sun noise becomes.

A new technology of balancing geared metal resonators of cylindrical Coriolis vibratory gyroscopes (CVG) for strap down inertial navigation systems of low and medium accuracy was proposed. Removal of an unbalanced mass from the teeth surfaces was performed by a high-precision electrochemical method. The proposed balancing algorithm allows to eliminate lower forms of mass defect, one by one or simultaneously, affecting the instrument operation. The algorithm does not require complex calculations when determining the mass removed from the teeth, and it could be used with any number of teeth on the edge of a resonator. The developed technology of balancing can be easily implemented and automated, it does not require expensive equipment.

The author considers application of CCD photodetectors designed to work in the frame accumulation mode for usage in the modes of time-delay and accumulation. A set of matrix and linear CCD photodetectors was determined for the problem of constructing digital cameras of pulsar astronomy processors. A special time diagram of control signals of frame CCD photodetectors, which provides special time-delay and integration mode, was proposed. An algorithm for switching modes of CCD photodetector, which takes into account the transition process, was developed. For the first time modes of time-delay and accumulation were implemented for two types of frame CCD photodetectors. Principles of constructing digital cameras with accumulation changeover, frequency control and frame synchronization were derived. Implementation of digital cameras based on a digital signal processor was presented.

The authors consider application sedimentation from the starting layer, which allows one to record large grains in a test sample, unlike other sedimentation methods. The analyzing method for grain-size composition of powders and particles of geological material was considered from a perspective of transformation of obtained information in a hardware component of a device as the most suitable for algorithmization of processing measured data when using the sedimentation analysis from the starting layer. Special attention was paid to the analysis of discrete values of the accumulative function by the linear method with a possibility of implementing this method as software.

The aim of this work is to optimize parameters of onboard laser ranging systems (LRS) in order to control rendezvous and docking of spacecraft. Systematic analysis of the factors that have to be considered when developing onboard laser ranging systems of spacecraft was carried out. The authors developed a computer program designed to simulate characteristics of onboard laser ranging systems with different values of their parameters. The authors solved the problem of multi-criteria optimization of parameters of laser ranging systems by criteria of maximum range and safe viewing distance. Use of Pareto optimization provides a set of solutions from which developers can choose the most suitable for technical implementation.

This article presents results of development of an automatic segmentation algorithm for fluorescent microscopic images of cell culture preparations in microbiology tasks. The segmentation algorithm is based on the Niblack local adaptive threshold  inarization of cells images in the V channel of the HSV color space, and images of inclusions of intracellular parasites formed with the use of the modified method of color deconvolution. Practical usage of the segmentation algorithm became possible due to the development of the fast algorithm for the Niblack local adaptive binarization. The fast algorithm is based on construction of two integral representations of the original image: a classical integral image and an integral squared image used for quick calculation of local standard deviation of intensity values. The proposed method provides reduction of binarization running time by 5 orders on average. Introduction of the algorithm into microbiological laboratory practice would eliminate the negative impact of fluorescence on doctor’s eyes caused by visual microscopic analysis of cell culture preparations, significantly reduce complexity and time of the analysis of one preparation and increase overall accuracy of the cultural method.

During ammunition exploitation premature actuation and failures may occur. It’s virtually impossible to fully eliminate such potentially dangerous situations. This article provides an analysis of failure reasons based on the experience of WWII; it also describes fuse modernization after the war. If we speak about artillery ammunition, their abnormal performance can occur at different stages of fuse operating: during service exploitation (as a result of a fall during handling); during loading (wrong loading); during ammunition movement inside the weapon bore (as a consequence of ammunition and fuse defects); when moving after flying out. The last case was considered in detail, and the final results of the research were presented by the example of specific fuses used in the army of Russian Federation.

The article describes a method of calculation of electrical admittance values of a low-frequency ultrasonic oscillatory system with a piezoceramic electro-acoustic transducer in interaction with biological tissues with an allowance for geometry and acoustic characteristics in COMSOL Multiphysics. Using this method, values of natural resonance frequencies of longitudinal oscillations and electrical admittance of the system at various geometry of loading were calculated. Possibilities of using the proposed method and a model with simplified geometry under the assumption of isotropy of the elements materials for calculation of natural resonance frequencies of longitudinal oscillations and electrical admittance of the system were also shown.

The authors describe a laser lidar model for remote measurement of instantaneous speed and direction of atmospheric winds. The authors provide the results of experimental studies in the surface layer of the remote correlation laser method for measuring instantaneous wind speed and characteristics of aerosol backscatter coefficient heterogeneities of the atmosphere. It is shown that the measurement of aerosol size heterogeneities and adaptive selection of size measurement framework in accordance with the found criterion can increase determination accuracy of instantaneous wind speed by correlation lidars.