The goal of the study is developing of the methodology of X-ray microanalysis of light elements C, N and O which are jointly present in various minerals and synthetic compounds, including ultrafine diamonds, carbon filamentous fibers, etc. An accelerating voltage of 10 kV high enough to reduce the contribution of the sample surface to the intensity of the lines, and at the same time prevent from the overestimation of the corrections for the line absorption was used. The beam current ranged within 90 - 120 nA. The lines of nitrogen and oxygen are particularly strongly absorbed by carbon. The background intensity is measured near the line. In the region of Kα lines of C and O, the background changes linearly, while for oxygen exhibits a large slope. The shape of continuous X-ray spectrum from the sample at 10 kV in the region of the nitrogen line can be approximated by a polynomial dependence. We used a differential mode of the amplitude discrimination of the signal. It is shown that the position and shape of the carbon line depends on the type of the chemical bond: from covalent (diamond, graphite) to a more ionic bond with oxygen (carbonates). Wide in diamond and graphite Kα lines are shifted in carbonates to the shortwave region and substantially narrowed. An additional maximum appears due to admixing of the wave functions of 2p electrons of carbon to the wave functions of 2s electrons of oxygen. The errors related to the influence of the type of chemical bond on the shape of the spectra can be avoided by the analysis of the integrated intensities. In some cases, the resistance of the samples to the impact of the electron beam is increased by the raster mode of size 5-8 micron or by moving the sample within the area ~100 x 100 pm². Calculation of the concentrations was carried out in the PAP program using B. L. Henke absorption coefficients. Some errors in the correction factors for the line absorption are usually corrected by selecting the absorption coefficients. The detection limit of carbon is 0.10 % wt. and for oxygen in carbonates it ranges within 0.39 - 0.90 % wt., whereas in the samples grown from nano-diamond colloids attains 0.75 wt. %.

A method for determining macro- and microelements in dairy, meat and fish food products and food raw materials by atomic emission spectrometry with microwave plasma generation (MP-AES) has been developed and certified for evaluating their nutritional value and safety. Method MP-AES is rarely used in laboratory practice due to the lack of methodological base for food control. The developed method provides experimental determination of P, Ca, K, Na, Mg, Fe, Zn, Cu, Mn, Cr, Cd, Pb, and Sn, the relative measurement uncertainty for all the elements being 30%. For sample preparation the refined standard (according to GOST 31671) procedure allowed us to eliminate all matrix interferences. The new tehnique provides necessary sensitivity for all aforementioned elements in accordance with the requirements of the regulatory documents. Some limitations in the sensitivity touch on analysis of infant milk formula for Pb and Mn; Cd is recommended to be determined in the products with maximum permitted level less than 0.2 mg/kg. The accuracy of the procedure was proved in analysis of the certified materials and interlab comparing experiment with atomic absorption spectroscopy and spectrophotometric methods. The MP-AES method implements fast procedure of analysis, with high reproducibility and accuracy. Along with low cost of the procedure, all the advantages allow us to consider MP-AES a promissing method of food quality control.

A technique for analysis of secondary tungsten-containing raw materials (tungsten-containing sludge) using inductively coupled plasma atomic emission spectrometry in combination with microwave autoclave sample preparation has been developed. The composition of the acid mixture and algorithm of microwave heating of the autoclave are chosen to provide a complete quantitative transfer of the sample into a convenient analytical form for subsequent ICP-AES determination of the main components (sample heating to 220°C in the acid mixture of NH₄F, HNO₃, and HCl provides a quantitative transfer of the sample components to be determined, into the solution). Analytical lines free from spectral interference were selected to determine Ti, Cr, Fe, Co, Ni, and W We used real industrial samples of secondary raw materials obtained in product manufacture from VK-type hard alloys [solid solution of tungsten carbide grains (WC-phase) in cobalt (Co-phase)], presented in the form of tungsten-containing powders, grinding sludge of solid sintered alloys, dust waste, defective mixtures, waste ventilation systems, and carbide powders. Correctness of the element determination was proved in analysis of ferrotungsten standard samples upon determination of the matrix component (tungsten) and by the methods of additives and sample weight variation upon determination of the alloying elements and impurities. The method of internal standard (with Sc as the element of comparison) was used to improve the precision and accuracy of the tungsten determination. The relative standard deviation was thus reduced from 0.03 to 0.004. The developed precise rapid technique was tested in analysis of industrial samples of secondary tungsten-containing sludge of hard alloys. The technique is recommended to control the composition of the secondary tungsten-containing sludge of hard alloys in a wide range of concentrations.

The results of studying granulometric composition and iron content in wire dry drawing grease are presented. The goal of the study is to estimate the possibility of extending a period of full replacement of grease in rough and intermediate wire drawing. Iron gets into the grease upon drawing both as a part of residual scale oxides and directly from the wire surface. Moreover, a gradual grinding of the grease also degrades the quality of drawing. The grease quality was estimated by two parameters: particle size distribution and iron content. The mass fraction of iron in the dry grease was determined using a specially developed technique. Iron compounds were first dissolved with hydrochloric acid and then separated from fatty acids. The iron content was measured using an optical emission spectrometer with inductively coupled plasma. The granulometric composition was determined by sieving. Test samples were taken from new original grease and from the soap-boxes of medium and coarse drawing machines. The dynamics of iron accumulation and change in the particle size distribution of the grease in the process of wire drawing were assessed proceeding from the results of measurements. The frequency of complete replacement of grease in soap-boxes was evaluated from the view point of the rational use without compromising the production effectiveness of drawing. Recommendations are given regarding decrease in the frequency of partial replacement of the grease in soap boxes in blocks N 4 - 6 in coarse drawing machines and blocks N 5 - 7 in medium drawing machines due to control of iron accumulation.

The results of studying the strain state and depth of dents in K08Yu low-carbon steel plates of small thickness (3-5 mm) using the method of coercimetry are presented. It is known that mechanical stresses and strains that occur in steel rods and base metal of oil and gas pipes have a significant impact on the magnitude of the coercive force (CF) near the sample surface. The effect of plate deformation and geometric dimensions of the dents on the CF magnitude is analyzed using a KM-445.1 coercimeter and tools for stepwise determination of the depth of dents (calipers with a depth gauge, tape measures, metal strip, marker). The calculated differential dependences linking the curvature of the plate with the dent depth are obtained. The intensity of linear strains occurring in the plate is determined. The relations between the coercive force and strain characteristics of plates with different types of collapsing are determined, namely, it is shown that in a plate with a single dent, the value of the coercive force increases monotonically with the depth and intensity of deformations, whereas in a plate with a double dent, there is a complex wave-like dependence of the coercive force magnitude on the depth and intensity of deformations with a characteristic inflection point and the character of the dependence provides a possibility for determination of the size and type of the dent. The proposed analysis of the stress state using the method of coercimetry makes it possible to detect geometric imperfections on the surface of the plates and carry out their non-destructive diagnostics.

The experimental results of testing the operation features of a SF-56 spectrophotometer are presented. Methods for processing the results of measuring the intensity of radiation sources using Maxima and Gnuplot software packages are developed to increase the accuracy of measurements. The use of the Gaussian function in approximation of the emission curve of low-pressure gas lamps for a nominal slit width of 0.3 nm increases the accuracy of determination of the wavelength of the maximum of emission lines by 2.5 times compared to the passport data. However, the effective width of the slit defined as the half-width of the reference line 486 nm (or 656.1 nm) always exceeds the passport values by 15 - 20%, and for a nominal slit of 1 nm by a factor of 1.5. The wavelength of the maximum of the SF-56 reference line (during the measurement time up to 6000 sec) linearly depends on time. The dependence of the reference line intensity on the heating time turned out to be nonlinear and is well approximated by the formula for an oscillator with a damping factor equal to the natural frequency. An analytical expression for the spectrum of the tungsten emission coefficient in the wavelength range of 300 - 1100 nm was derived. The Planck curve for the tungsten emissivity describes the spectrum of the signal of a standard incandescent lamp only in the wavelength range of 300 - 420 nm. The spectral function of the instrument is also determined. It is noted that SF-56 spectrophotometers can be used to measure the spectra of radiation placed in the lighting unit. The presented data can be used both to improve this type of devices, and to improve the accuracy and reliability of measurement results.

Diagnostics of damage to the parts of aircraft engines provides valuable information about the causes of damage and guidelines for developing recommendations for prevention of the flight accidents. The use of the results of diagnostics of turbine blade failures in service and analysis of the operating experience gained upon operation of the aircraft engines are the necessary conditions providing high reliability of turbine blades. The goal of the study is analysis of the in service destruction of the turbine blades of aircraft engines, development of methods of damage diagnostics, evaluation of the blade health and vitality, elucidation of the causes of service failures, development of safety recommendations and implementation measures preventing the destruction of the turbine blades in operation. Methods of fractographic and metallographic analysis as well as computational and experimental methods are used to assess the performance and survivability of the blades. The results of the diagnostics of the service failures of the turbine blades of aircraft engines, methodological aspects of the research in determination of the destructive value of the AC voltage amplitude, identification of the sequence of actions of the prevailing damage mechanisms, determination of a decrease in the safety factor of the fatigue strength and the value of the threshold size of crack-like defects for different levels of vibratory stresses, and determination of the duration of the fatigue crack growth are presented. Methodical approaches thus used and results of the service failure diagnostics allowed us to obtain the new data on loading, workability and survivability of the turbine blades, as well as on the impact of the crack-like defects, the growth rate of fatigue crack in service conditions, elucidate the causes of service failures and specify the recommendations for their prevention.

The results of studying the processes of stress corrosion cracking (SCC) of low-carbon low-alloy steels are presented. It is shown that the use of eddy current method (ECM) allows one to evaluate even small structure changes associated with the processes of the SCC crack nucleation and growth. It is noted that the process of stress corrosion cracking exhibits a two-stage character, which is distinctly displayed in the electromagnetic characteristics. The first stage of the destruction characterizes the processes of accumulation of micro-damages in the material and ends with the formation of one or more cracks having the size of several grains. At the second stage the formation and growth of the macro cracks is accompanied by a rapid change of the electromagnetic characteristics. The dependences of the SCC incubation time on the value of the macroelasticity limit (σ₀) are given. It is noted that an increase in the o0 value entails an increase in the time prior to the formation of the first crack. This can be explained by the fact that the limit of the macroelasticity determines the onset of microplastic flow in the material that actively affects the stress corrosion cracking. An analytical dependence of the SCC incubation period on the value of the macroelasticity limit is obtained using experimental data. The calculation error did not exceed 10%. A parameter is proposed to assess the state of the material prone to SCC which allows detecting the stages of accumulation of micro-damages and exhaustion of a significant part of the material resource before the appearance of multiple surface macro-cracks proceeding from the data of eddy current measurements. It is shown that the eddy current method apart from determination of the macro cracks present on the surface provides identification of the stages of the material destruction under the simultaneous action of corrosive medium and static tensile stresses.

An electronic module of control and data acquisition and transmission “BUPSD 01” has been developed for the IMASh 20-78 test unit which can be used both as a stand-alone control device and in conjunction with a computer. The software has been developed that allows detecting of loads and deformations using sensors, setting the speed of the grasp movement, and carrying out photo and video shooting with simultaneous construction of test schedules. As a result of the deep modernization of the unit developed more than thirty years ago, an almost new testing machine equipped with modern electronics with a wide functionality was obtained. Three stationary control racks and module of video recorder-monitor playback system are replaced with data acquisition and transmission control module, WEB camera and personal computer. Combination of the reliable mechanics (reduction gears, electric motors, grippers), which is part of the original installation with modern electronic equipment and software, allowed using of the unit at a qualitatively new level of research. In a modernized form, the unit is capable of continuous recording of data on loading and deformation into a text file and plotting a process schedule using this information storing it in the file. The video system control the entire test process with a WEB camera mounted on a microscope and record it in a file with the possibility of subsequent playback. Moreover, the system can take photos at any time and save them on the computer. The device has been tested in the study of the samples of metal alloys with various galvanic coatings and polymer composite materials. Information about new characteristics of the studied materials became available now in addition to the mechanical characteristics obtained earlier.

It is shown that the description of the error corridor of the model, obtained under the assumption that the inaccuracy of the source data is specified in the interval form, in contrast to the statistical approach, is given by four functions instead of two and can be represented by linear spline functions, where the first pair of functions describes the error corridor inside the range of change of the input variable in the experiment, and the second pair — outside this range. The problem of analyzing and developing of the methods for approximation of the static characteristics represented as linear splines by smooth functions of the second order is solved. It is also shown that second-order polynomials and implicit functions in the form of conic sections can be successfully used for approximation of linear splines which define the error corridor. A computational experiment was designed within which the criteria determining the accuracy of the solution of the approximation problem were formulated and the areas for placing experimental points on the boundaries of the interval corridor (on the basis of which the coefficients of the approximating functions were calculated) were determined. The developed experiment minimizes the number of calculation points when the specified accuracy of the solution of the approximation problem is ensured. It is shown that when a quadratic function is used for approximation of the boundaries of the interval corridor, the calculations can be carried out for only one of the boundaries with subsequent simplest calculation of the parameters of the other boundary which almost halves the computations. Approximation of the linear splines that define the uncertainty corridor requires the use of no more than 30 experimental points. Comparison of the results showed a slight difference in the criterion values when polynomial or implicit function are used for approximation with a slight advantage of the approximation by a polynomial function.

We consider one of the sequential parametric methods for detection of the so-called “disorder” of a discrete random process, i.e. spontaneous change of its probabilistic characteristics. Among the variety of the algorithms, the most common are those based on modified sequential analysis, usually referred as cumulative sums algorithms (CUSUM-algorithms). The aim of the work is to study the CUSUM-algorithm designed to detect changes in the variance of the Gaussian time series. The initial statement of the problem is formulated. The probabilistic characteristics of the algorithm are studied by the method of simulation experiment. The dependences of the average interval between false alarms and the average delay time in the detection of the disorder on the value of the decisive threshold for different values of the indicator characterizing the value of the variance change in the disorder are obtained. It is shown that the algorithm under consideration is more effective for detecting an increase in the variance compared to the case of its possible decrease. A method for synthesizing the controlling algorithm with the specified probabilistic characteristics is proposed. Study of the stability of the method in relation to the inaccuracy of setting the variance for the initial state without a disorder revealed that even relatively small errors in the value of the variance lead to rather large deviations of the actual probabilistic characteristics of the algorithm from those specified in the synthesis procedure. This poses rather stringent requirements for the number of observations when the variance is estimated from the experimental data. A simplified relation for determination of the sample size required for estimation of the standard deviation with a given permissible relative error at the selected confidence probability is presented. The results of the study can be used in construction of the control cards designed to solve the problems of statistical management of various processes.