Measurement Techniques

Methods and devices for measurement of the disperse parameters of aerosols, suspensions, and powderlike materials included in the improved version of GET 163–2010 are described. A comparison of the metrological characteristics of GET 163–2010 before and after improvements have been introduced into the standard is presented. The problem of divergence of the results of measurements obtained by different methods implemented in the working measurement instruments from the results of methods achieved in standard devices is solved.

The need for a systems approach to the study of the robustness of techniques of performing measurements is evaluated. A model of losses of robustness of a measurement method by means of which the complete set of external and internal influencing factors may be identified is proposed based on a process model. Factors responsible for losses of robustness of the first and second kind are identified. Algorithms for identification and analysis of loss factors as well as control of these factors, including the application of Taguchi methods, are evaluated A conception of a complex technique of studying a measurement method on the stage of validation is proposed.

A method of investigation of processes that arise in aggregation of nanoparticles in colloidal solutions based on estimation of variations in the coefficients of rotational diffusion of nanoparticles is proposed. It is shown that rotational diffusion is more sensitive to variations in the dimensions of the particles than is translational diffusion. A comparative estimation of these types of variations is presented and the relative index of aggregation is calculated from the integral values of the autocorrelation function of depolarized dynamic light scattering. Results of numerical simulation of the proposed method and its experimental certification are compared.

This paper describes a measurement-circuit design approach based on switched-capacitor filters, and an analog vibroacoustic signal-matching-and-conversion device. We also develop an adaptive control algorithm for measurement-circuit parameters, and find that analog matching devices can be used advantageously for and monitoring and diagnostics of process status in industrial equipment.

We present the results of development of a prototype of cavity-type model of black body in the form of a graphite ampoule filled with a δMoC–C eutectic alloy of molybdenum with carbon that realizes a high-temperature reference point (HTRP) of 2856 K on the temperature scale. It is shown that the created ampoule may serve as a precision “type-A” optical radiation source. We justify the approaches to the evaluation of the uncertainty components of emissivity of the ampoule cavity equal to 0.9997 with an extended uncertainty of 0.00016 (k = 2) depending on the geometric and physical parameters with the help of numerical algorithms based on the Monte-Carlo method.

We consider a frequency-diaphragm technique of simultaneous standardless measurements of the efficiency of photon detection by two single-photon counters. This technique is based on the well-known scheme of measurements of the efficiency of detection of single photons with the help of photon pairs generated in a nonlinear crystal in the case of spontaneous parametric scattering. As a specific feature of the proposed procedure, we can mention the application of spectrally asymmetric optical channels. An experimental installation aimed at the realization of the proposed procedure in the degenerate mode of spontaneous parametric scattering is described. The results of simultaneous measurements of the detection efficiency of two single-photon counters at a wavelength of 810 nm are presented. The counters are constructed on the basis of SAP-500 silicon avalanche photodiodes with fiber inputs. It is shown that this technique can be also used for measuring the detection efficiency of single-photon counters sensitive in a more long-wave region of the spectrum. As compared with the pure diaphragm scheme, the proposed procedures has advantages in the simplicity and reliability of adjustment.

A method of calibration of devices used to measure energy by means of a calorimeter and reference photodiode is described. Experimental results of the calibration are presented. Through the use of the method, energy meters, photodetector devices, and radiation sources may be calibrated over a range more than 10⁸ times the measured radiant energy with the use of time conversion.

Two-signal and modified two-signal methods for measuring the S-parameters of transistors are examined, along with a method developed for adequate measurement based on these methods. The uncertainty of the last two methods is eliminated. The methods are implemented using a simulator-analyzer for the amplifiers and microwave self-oscillators in measurement channels of the simulator-analyzer that are matched and unmatched to the loads. The range of applicability and the interrelationship of these methods are studied and their advantages and disadvantages are pointed out.

The measurement function is calculated for the modulus of the vibration acceleration vector of three-component vibration transducers by means of a unicomponent calibrating vibration shaker. Two options for defining the measurement function of the modulus of a vector are analyzed: calibrations against one- and three-component reference vibration transducers. Formulas for finding the measurement function of the modulus of the vibration acceleration vector and calculating errors are given. Experimental results that confirmed the theoretical studies are provided.

Mathematical models have been developed for the calculation of measurement errors of the coefficients of the heat conductivity and thermal diffusivity of thermal insulating materials. A technique for selection of the following optimal parameters was created, based on models: duration of the heat pulse and the chief structural dimensions of the measuring device. Optimal conditions for applying the algorithm for processing the experimental data were also defined.

New structural designs of integrating devices by means of which the precision of integration of electrical signals in the range of ultra-low frequencies 2·10^–3–3 Hz may be increased are presented. Practical designs of second-order integrators and their transfer functions are considered. Results of calculations that confirm an increase in the precision of integration of signals by a second-order integrator by comparison with a first-order integrator as a function of the frequency of the device are presented.

It has been shown that methods currently being used for measuring group delay in an antenna in an anechoic chamber are limited in precision due to the effect of residual reflections. A method has been developed to decrease the effect of reflections, with a linear approximation for the effect of a delay on the distance between antennas. The method is based on the assumption that the group delay between the input of the radiating antenna and the output of the receiving antenna in the far-field region depends linearly on the distance between antennas, and the interference caused by the residual reflections is of periodic nature. The method that was developed, compared with the method of determining the delay for a fixed distance that was used previously, made it possible to improve the precision of measurement by a factor of greater than 6.

The methodical features of measuring the power of acoustic radiation of model panels in the field of aerodynamic pressure pulsations are considered. We show the possibility in principle of using intensimetry in the near field of a vibrating surface. We establish the effect of static loading of the panel on the power of its acoustic radiation in the vicinity of the first resonant frequencies. It is shown that the effect decreases with increasing frequency.

Studies have been performed to improve the accuracy of energy measurements of neutron fields and to improve the spectrometric analysis of neutron radiation fields using scintillation detectors. The use of a scintillation detector based on ⁶Li₂O lithium glasses of various diameters and thicknesses for recording neutron radiation energy, 0.4–15·10⁶ eV, is considered. The main characteristics of this scintillation detector and the results of measurements obtained with it are compared with the characteristics and results of measurements of the scintillator using LiI (Eu). Spherical moderators with diameters of 70–300 mm were used for scintillation detector operation.

The article is devoted to the issues of conceptual development of a new generation of electrocardiogram imitators. A mathematical model is proposed for simulating ECG signal considering the variability of biosignal morphology, the presence of various distortions and artefacts, heart rate variability and respiratory modulation of ECG signal. A block diagram of the ECG simulator was designed.