The ratio of NMR frequencies of lithium isotopes was determined: f(⁷Li)/f(⁶Li)=2,6409061846(13) with an error of 4,9·10^–10. We used a spectrometer mode with simultaneous recording of signals from two cores, which allows us to reduce random and systematic errors by an order of magnitude. The ratio of the resonant frequencies of water protons and ⁷Li ions was determined: f(H₂O)/f(⁷Li)=2,557100473(9) with an error of 3,5·10^–9 for solutions with an extremely low concentration of LiOH*H₂O salt in water and at a temperature of 25 °C. Based on the data obtained, the magnetic moments of lithium nuclei were calculated: μ(⁶Li)=0,8220454(25)μ_N; μ(⁷Li)=3,2564171(98)μ_N. The known data on the magnetic moment of the proton and data on the electronic shielding of these nuclei were used. The comparison of experimental data on μ(⁶Li) and μ(⁷Li) with data from theoretical calculations is discussed.

A new solution to the problem of nonlinear parameter estimation is considered. The peculiarity of this problem is that the arguments of a nonlinear function are not only the measurement data and the required parameters, but also supplementary parameters. Supplementary parameters are a priori unknown, but they are necessary only to find optimal estimates of the required parameters. The estimate of the desired parameters is formed according to the point-mass method as a weighted sum of partial estimates obtained for the specified values of supplementary parameters. This solution allows us to eliminate a priori probabilities for supplementary parameters by taking into account additional covariance of weight coefficients and (or) specified partial estimates. The considered approach is effective in solving specified nonlinear estimation problems characterized by low accuracy of available measurement data and (or) their few number

The design and operation principle of a multi-sensor Converter of binary mechanical signals into electrical signals based on a partitioned fiber-optic digital-to-analog Converter with a parallel structure is considered. The digital-to-analog Converter is made from a set of simple and technological (three to five digit) fiber-optic digital-to-analog sections. The advantages of the optical scheme of the proposed Converter in terms of metrological and energy characteristics in comparison with single multi-bit converters are justified. It is shown that by increasing the number of digital-analog sections, it is possible to repeatedly increase the information capacity of a multi-sensor Converter without tightening the requirements for its manufacturing technology and element base. A mathematical model of the proposed Converter is developed that reflects the features of its operation in the mode of sequential time conversion of the input code vectors of individual fiber-optic sections into electrical analogues and the formation of the resulting output code vector.

An analysis of the errors of the measuring optical power divider of laser radiation, which is used to transmit a unit of average power of high-intensity laser radiation and is structurally made in the form of a wedge, is carried out. The error of the division ratio, which affects the accuracy of the unit transmission, is determined. The estimation of the random component of the division coefficient error is carried out and it is shown that the proposed method for its determination, based on the rearrangement of the used measuring instruments, gives the most probable estimate. The error caused by the nonlinearity of the measuring instruments that determine the division coefficient is investigated, and its largest interval is estimated. It is shown that in the case of invariability of the conversion coefficients of the used measuring instruments on the laser radiation power, the method makes it possible to exclude the dependence of the error in determining the division coefficient on the mentioned coefficients, and in another case, to reduce their influence on the transmission error. The possibility of controlling the division factor of the divider by determining the control parameter and its confidence interval when transmitting a unit of radiation power is substantiated; a formula for calculating this interval in each measurement cycle is obtained. It is shown that the value of the parameter and the change in the confidence interval can be used to control the reliability of the transmission of the unit of power to the calibrated measuring instrument in real time.

This article describes the processing technique of measuring phasechronometric information based on the neural networks use. The novelty of the proposed approach lies in the choice of a classification feature and the perceptron algorithm use as an algorithm for binary classification performing. In this article, to assess the concept operability, the simplest binary classification of the lathe operation modes is made: idle or cutting.

The characteristics of non-contact sensors for measuring displacements, deformations, and vibration parameters using processes of various physical nature are compared. Within the framework of the diffuse-mirror reflection model, the efficiency of using optocouplers for developing non-contact vibration displacement sensors is substantiated. The urgent tasks of research and development of sensors using near infrared radiation reflected from the surface of the controlled object are formulated. The research technique based on modern algorithms and means of digital processing of vibrosignals is given. The difficulties of studying the metrological characteristics of sensors in a wide dynamic and frequency ranges using electrodynamic vibration stands are considered. The results of a full-scale study of the basic metrological characteristics of a prototype optoelectronic sensor providing measurements of displacements with an amplitude of up to 5 mm in the frequency range from 0 to 3 kHz are presented. The results of analysis of the amplitude-frequency characteristics of the sensor in the range from 5 Hz to 3 kHz, obtained using two disks made on a 3D printer, are presented. The advantages and disadvantages of non-contact sensors based on infrared optocouplers are given.

Non-contact aerohydrodynamic methods, unlike other non-contact methods, allow highly accurate determination of the viscosity of inhomogeneous and opaque liquids in any industry in the interval of 2–100 Pa·s. The pulsed aerohydrodynamic method was proposed about thirty years ago, and is the most promising of the non-contact methods, but it has not received proper development. The method consists in deforming the surface of a tested liquid with a gas jet and determining the viscosity from the time takes to reach a predetermined degree of deformation from the moment when the gas jet was applied. The paper presents the results of studies of a non-contact aerohydrodynamic device for measuring viscosity with a laser triangulation detector of the liquid surface, the use of which made it possible to fully automate the device and significantly increase the accuracy of viscosity measurements. The aim of the research is to choose the most promising of four possible variants for implementing the device. The choice was made according to criteria, the fulfillment of which ensures a decrease in the sensitivity of the device to influencing quantities, and an increase in the measurement accuracy. A description of the design and principle of operation of the device is given. The results of studies of design parameters influence on the systematic and random components of the measurement error are presented. The relative error in measuring the viscosity of liquids in the interval from 2 to 100 Pa·s does not exceed 2 %. The developed non-contact aerohydrodynamic device is advisable to use in testing of viscous liquids in various industries.

The urgency of the work is caused by that at research of heat conductivity in anisotropic materials is necessary to consider infringement of parallelism between vectors of heat flux and a gradient of temperature. In the previous works at studying heat conductivity of pyrolytic graphites techniques which were applied to isotropic graphites were used. Results of measurement of heat conductivity of pyrolytic graphite of mark UPV-1 in a direction in parallel to a plane of sedimentation are presented. The experimental samples which are heated up by an electric current, represented hollow cylinders at which the plane of sedimentation of pyrolytic graphite has been located along radius. It is offered also heat flux which defined on energy of radiation from an external surface of the sample, and a gradient of temperature to measure along radius, that is strictly in parallel each other. The comparative analysis of experimental data of heat conductivity (in parallel a plane of sedimentation), measured in the given work and resulted in literature sources is brought. The range of the investigated temperatures makes 1900–2950 K and is expanded in area of higher values on 450 K.

In this paper, a practical application variant of the high-temperature spectral thermometry method for controlling the temperature of a dielectric object heated in a high-intensity microwave electromagnetic field is proposed. The advantages of using the spectral pyrometry method over the methods of color and brightness pyrometry when registering high temperatures (from 500 °C and above) are described. The optical fiber cable used in this method, which receives thermal radiation from an object heated in the microwave field, is subject to the negative influence of the electromagnetic field, which leads to its unacceptable heating and failure. To eliminate this phenomenon, a non-standard use of an cutoff waveguide placed not outside, but inside the microwave heating chamber is proposed. It is shown that this solution completely eliminates the negative influence of the electromagnetic field on the fiber optic cable and allows placing the receiving end of the cable in close proximity to the object being heated. The calculation of geometric parameters of the cutoff waveguide for the operating frequency of the electromagnetic field of 2450 MHz is given.

Results of synchronous electric and magnetic fields measurements made by different types of sensors in the frequency range of 0.002–7000 Hz are covered. Different approaches to obtaining the evaluation of sensor noise are considered. The technique of quantitative estimation of level of natural noise of each sensor and characteristics of a natural field on the basis of two- and three-channel scheme of synchronous measurement is given. Comparison of experimental noise estimations with computational ones is given. It is shown that the magnetometer based on magnetomodulation transducer has an unacceptably high level of its self noise for using it in applications related to the measurement of natural geomagnetic field.

The influence of environmental conditions on a sound pressure reproduced by the primary method in the measuring chambers of the Pistonphone in the frequency range from 1 mHz to 250 Hz is estimated. Numerical estimations of influence of environmental conditions on sound pressure in pistonphone measuring chambers are given and special requirements to system of maintenance of required external conditions are specified.