Vol 62, No 8 (2019)

The composition of State Primary Standard of the unit of activity of radionuclides, unit of specific activity of radionuclides, and unit of flux of α and β particles and of photons of radionuclide sources GET 6–2016 and its metrological characteristics are presented. Two new standard plants that implement absolute methods of measurement of the specific activity of radionuclides are introduced in GET 6–2016: the method of ratios of triple and majority double coincidences in a liquid scintillator and the 4πγ counting method. Results of international key and auxiliary comparisons that confirm the measurement capabilities of GET 6–2016 are described. Variations of the measurement chain that take into account the capabilities of GET 6–2016 are considered and existing metrological applications of GET 6–2016 that support the required precision of radiometric measurements in atomic energy, science, medicine, radio ecology, defense, and other areas of application are considered.

A fast procedure is proposed for choosing the blur coefficients of kernel functions in a multidimensional nonparametric estimation of the equation of a decision surface for a two-alternative problem of pattern recognition. The decision classification rule meets the maximum likelihood criterion. The theoretical basis of the procedure under consideration is the result of a study of the asymptotic properties of multidimensional nonparametric estimates of the decision function in the problem of recognizing patterns and probability densities of the distribution of random variables in classes. The possibility of using fast procedures for choosing the blur coefficients of kernel estimates of probability densities in the synthesis of non-parametric estimates of the equation of the decision surface between classes is substantiated. The effectiveness of the proposed approach is confirmed by the results of computational experiments.

The problems of increasing the accuracy of numerical differentiation in the measurement model are investigated. We consider the measurements of target characteristics of an object that are not directly measurable, and also the reduction of measurements using the example of determining derivatives and initial parameters in the Cauchy problem. We clarify the relationship between the initial parameters of the differential dependencies and particular solutions of the differential equation of the Cauchy problem at the measurement points of the input quantities of the measurement model. Using the example of determining the derivatives in the Cauchy problem, we note the efficiency of the Lagrangian approximation of the functions of the input and output quantities of the measurement model. It is shown that the maximum accuracy of the approximation of the studied characteristics of the object is attainable using the theory of inverse problems. The following scientific results were obtained: assuming the form of the differential equation for the Cauchy problem, particular solutions of the equation are found; using a polynomial approximation, we compute the function of the measurement model input parameters measured by the sensors; we derive formulas for computing the derivatives of the function of input quantities; by the method of measurement reduction, an approximation grid is determined that minimizes the influence of sensor error. We propose a criterion for estimating the efficiency of solving the measurement reduction problem. Formulas are obtained for estimating the level of error in the derivatives of the function of the input quantities, taking into account the given sensor error. It was shown that the experimental results are consistent with the theoretical ones. The applications for the research results include information-measuring systems for monitoring the status of complex technical objects.

We present the description of an automated hardware-software complex intended for measuring the 3 dB frequency of modulation and evaluation of the quantum efficiency of separate spectral components of the full spectrum of electroluminescence of light-emitting diodes, including the range of low levels of excitation. The principle of operation of this complex is based on measuring the spectrum of radiation of a light-emitting diode with the help of an OceanOptics USB2000+ spectrometer in the signal-accumulation mode in the course of transmission of current pulses with given amplitude and repetition frequency through the light-emitting diode with subsequent selection of separate spectral components from the full spectrum of radiation. We present the results of testing the hardware-software complex performed by measuring, as an example, the frequency characteristics of separate spectral components of the full electroluminescence spectrum of commercial InGaN green light-emitting diodes. The analyzed hardware-software complex can be used for the diagnostics of the quality of light-emitting heterostructures with quantum wells.

The application of atomic-force microscopy for nanoindentation of the surface layer of films of acrylate polymers filled and unfilled with highly dispersed iron powder is examined. The effect of the elasticity of the polymer and of introducing a nanofiller on the nanohardness of the surface layer of the polymer is analyzed. It is shown that the nanohardness of the surface layer of both unfilled and filled polymer films increases as the elasticity of the polymer is reduced. A correlation is observed between an increase in hardness and a reduction in the elasticity of filled polymers.

The features and problems of gem evaluation using “color” as a quality indicator that arise with the control method and the use of the existing GIA, State Registry of Measuring Instruments of the Russian Federation, and World of Color color classifiers are examined. A digital color classifier built on the principles of the Mansell atlas is proposed. The proposed classifier is intended for use in automated devices for instrumental evaluation of the color of gems. Using the example of the scale of green hues of color, the possibility of creating a system of digital standards corresponding to the colorimetric standards of the International Commission on Illumination (CIE) is shown. Requirements are presented for automated devices for instrumental evaluation of gem color.

The influence of errors of form (ovalities) of the base surfaces of a composite axisymmetric body on the size of an adjacent contour was studied. It was proved that ovalities of all bourrelets of a composite axisymmetric body do not render an effect on the accuracy of measurement of the size of entry of this case, although they do affect the entrysize. Errors of the placement of joined tubes of the composite axisymmetric body in the form of displacements or misalignments of axes cause measurement errors of the entry size of the casings that are proportional to the ratio of the distances from the basic prisms to the end faces of tubes vs. the length of the tubes.

We consider the main principles of construction of optoelectronic measuring systems in which the electric power supply of measuring modules is realized with the help of optical emission transmitted through a fiber light-guide. We present various versions of manufacturing of simple photovoltaic converters with a conversion efficiency of up to 50% based on the photodiode assemblies and AlGaAs light-emitting diodes. The factors limiting the power supplied by the optical emission are analyzed. The possibilities of realization of measuring modules based on self-excited generators with resistive and capacitive transducers based on multichannel analog-to-digital converters are presented. The methods aimed at decreasing the energy consumption of the measuring modules are analyzed.

We propose an express method for measuring the thermal diffusivity of the materials of products that does not require cutting out of the samples of special shapes from the homogeneous mass of the product. The method is based on the local heating of the surface by step-function pulses, e.g., by a focused laser beam with simultaneous high-speed thermography performed with the help of a thermal imager. The subsequent processing of a radially symmetric picture of isotherms carried out by using an original software program makes it possible to find the thermal diffusivity of macrohomogeneous materials with an error lower than 10%. As an example, we present the results of measurements of the thermal diffusivity of the ZrO₂:MgO ceramics, PhenoCure Powder composite based on phenol formaldehyde resin, and TPK-5PD polymeric-rubber material.

It is proposed that magnetic information parameters constructed from the parameters of the full magnetic hysteresis loop of steels be used for nondestructive testing of medium-carbon alloy steels. Analytic expressions for calculating the relative error in the determination of the magnetic information parameters are derived and analyzed. The measurement errors of the constituents of the parameters and the errors associated with the mathematical computations are taken into account. It is shown that the errors in the determination of the magnetic information parameters over the potential range of variation of the magnetic properties of steels is several-fold less than the relative error of the measurement of the relaxation magnetic parameters of steels. The use of the magnetic information parameters for nondestructive testing of the hardness of 40Kh steel in the range of hardness of practical importance is considered.

We discuss improving the reliability of measured DC and AC response curves for a bipolar transistor as a function of frequency using the mass-produced 2T937 transistor (Russia) as an example. We describe preparations for measurement and the actual measurements in considerable detail. We provide experimental response curves for the 2T937 transistor. A special test (measurement) board was developed to prevent the measured response curves from being affected in any way by the transistor mount or interface hardware (power buses, soldering leads, matching devices, adapters, etc.). A bare transistor chip was used to eliminate any effect of the transistor package on the results and improve the size and weight specifications of devices using the 2T937 transistor. The transistor chip can be directly mounted to a test board whose topology is used to connect the transistor chip to the device. The microstripline board is designed to enable measurements to be performed in the microwave frequency band using a probe station with standard calibration.

The methods of determination of Be, Cu, Fe, Ni, Si, Ti, and Cd in certified standard samples of magnesium alloys by inductively coupled plasma mass spectrometry (ICP-MS) are discussed. The procedure for dissolving the sample and preparing it for analysis is given. To eliminate spectral interference, a collision-reaction cell was used. An internal standard is selected and the accuracy characteristics of the magnesium alloy analysis method are calculated. The accuracy of the results is confirmed by analyzing a certified standard sample of magnesium alloy.