Vol 59, No 11 (2017)

Various methods for interpolation, smoothing, and neural network learning are examined. It is found that none of these methods is universal and absolutely reliable. Hybridization of these methods is recommended. Results are shown from a fuzzy neural network simulation with random location of the learning points and an unknown form of the sample distribution.

The construction of a contactless adaptive vibration sensor based on an externally modulated reflectometer-type fiber-optic transducer is discussed. The sources of measurement error and ways of reducing them are determined. An experimental prototype fiber-optic contactless adaptive vibration sensor and a method for correcting its transfer function are described.

Methods of determining the rate of fall of rain drops are reviewed. A description of an optical rain gauge whose principle of operation is based on the acquisition and analysis of shadowgraphs of particles of precipitation is presented. The error in the determination of the rate of fall of rain drops is estimated and the results of preliminary field measurements of the parameters of drops are presented.

A technique for measuring losses of the cross-sectional area in the metal of hoist ropes made of ferromagnetic steel wire for the purpose of estimating their performance is considered. An analysis of the efficiency of the measurement technique using a mathematical model of a locked-coil rope is performed and the measurement errors determined. Steps to improve the measurement technique are proposed.

Problems that arise in estimation of the mutual delays of signals in distance-measuring difference processing are considered. Based on field tests of similar radio-receiving devices, it is shown that mismatch of the receiving channels may lead to errors of up to several dozen nanoseconds and, as a consequence, significant errors in determining the location of sources of radio emission. A method of adjustment that makes it possible to reduce the error in estimation of delays down to 10 nsec is proposed and experimentally verified.

A comparative study is made of the use of transmission electron microscopy, dynamic light scattering, and acoustic spectroscopy for measuring the sizes of nanoparticles in stable colloidal solutions of Al₂O₃, TiO₂, SiO₂, and ZnO at different concentrations and mean nanoparticle diameters. For solutions containing dendritic agglomerates of nanoparticles along with individual nanoparticles, it is found that acoustic spectroscopy can be used to measure the sizes of individual nanoparticles and dynamic light scattering can be used to measure sizes of objects from a mass of nanoparticles and their agglomerates.

We present the dependence of the mass of commercial oil and petroleum products on the measured parameters – density, volume, measured fluid counter, pressure and temperature in operating and laboratory conditions, the volumetric expansion coefficient under atmospheric and gauge pressures in operating conditions at 15°C. We obtain an expression for the estimation of the relative error of indirect mass measurements of petroleum products. We present results of mass measurements for kerosene, aviation kerosene, and light diesel fuel.

The drawbacks of existing methods of measuring residual stresses are analyzed. Experimental investigations of the influence of external factors and of the structures and physico-mechanical properties of materials on the rate of propagation of ultrasonic waves are presented. Regression relationships are obtained.

We consider a method of transferring the temperature of the triple point of water with an acoustic resonator configuration for measuring the Boltzmann constant. It is shown that the transfer of the temperature of the triple point of water in a resonator using a highly sensitive differentiator does not require the use of absolute means of measurement and implemented with uncertainty limited only by thermal noise. The method enables reducing uncertainty in the temperature transfer when measuring the Boltzmann constant, whose accurate measurement is necessary for transition to a new definition of the unit of temperature.

We propose a microprocessor-based measurement system (MBMS) for measuring the modulus and components of the complex resistance of an individual two-terminal element and the complex resistance of a two-terminal element in a branch of a multiterminal electrical circuit (MTEC) of T type or H type with one and with two points that are inaccessible for connection of the complex resistance of the two-terminal element (CRTTE). We present the block diagram for the microprocessor-based measurement system and results of the study.

Measurement of the frequency dependence of the fluctuation rejection ratio produced by the microcircuits of linear voltage stabilizers by means of a modern oscillograph and generator without the use of special expensive equipment is investigated. The effect of the amplitude of the sinusoidal probe voltage to induce distortion of the form of the output signal of the stabilizer at different frequencies is studied. Questions related to the possible influence of the automatic scanning options and the lay-out and configuration of the printed board as well as the types, ratings, and assembly of the capacitors on the measurement results are considered.

Mathematical simulation is used to estimate the error in ultrasonic-echo measurements of the thickness of objects made of inhomogeneous materials with structural noise and frequency-dependent attenuation of ultrasound taken into account. Empirical formulas are derived for estimating the minimum measurement error.

A phenomenological model is proposed for estimating the changes in the composition of a microscopic volume during low-voltage electron probe x-ray spectral microanalysis. The changes are caused by the thermal effect of the electron probe. Equations are derived which relate the metrological characteristics of low-voltage electron probe x-ray microanalysis to the thermodynamic characteristics of the sample and to the experimental conditions. These results make it possible to choose a priori an analysis mode that avoids errors induced by thermal instability of a test object.