Vol 59, No 7 (2016)

The measurement methods and instrumentation for the national primary standard for the units of relative humidity of gases, molar (volume) fraction, and temperature of the dew point, GET 151-2014, are discussed. The structure of the standard is described. The metrological characteristics of the standard and the results of the international key comparisons CCT-K6 are reported.

The classes of methods for interpolating, filtering, and variational modeling that take measurement noise into account are extended and generalized. The advantages and disadvantages of these methods are pointed out and recommendations are made on the choice of methods for evaluating quality criteria and their control parameters for identification and recovery of geological fields based on the processing of noisy measurement data. Hybrid use of these methods is recommended.

A method for use in data-measurement systems for design and control of long-line networks is described. The model method is based on the numerical inverse Laplace transform in long-line systems. Its application is illustrated for systems with parabolic differential equations and linear coupling.

Thermophysical properties (thermal diffusivity, conductivity and heat capacity) of ferrofluids are investigated by the laser flash method within the interval of magnetic field induction 1.594–3.866 mT while varying the content of added iron powder in the range of 0.1–0.3 g at room temperature.

A method for the measurement of the S-parameters of semiconductor devices by means of a vector network analyzer and probe station in the millimetric range of frequencies is considered. A high level of precision of measurements is achieved through successive elimination of all error sources. Relationships that relate the effective parameters of the measurement system and the maximal error are presented. An experiment is carried out and results compared to analogous studies.

The method of partially depolarized dynamic light scattering is applied to measurements of gold nanorods dimensions in liquids using translational and rotational diffusion coefficients. Compared with the known methods, the new method makes it possible to lower the power of the existing laser radiation and to increase the data set for solving the inverse problem. Nanorod lengths calculated from the diffusion coefficients are in agreement with TEM data. Aspect ratios calculated from extinction spectra in the plasmon resonance domain are in better agreement with TEM.

We describe the operating principle of a two-diode autodyne and the basic methods of non-contact determination of product size. We consider the application features of two-diode autodynes in determining the sizes of products by the Doppler method, as well as a phase method for determining small deviations of the controlled product from a reference sample.

The use of the nuclide ²²⁹Th as a new nuclear-optical frequency standard is studied theoretically. The mechanism for two-photon optical pumping of the 7.6 eV isomer through the optical shell in singly charged ions is examined. The decisive role of the 8s–7s resonance transition is demonstrated. It is shown that the required energy of the two photons is equal to the sum of the energies of the nuclear level and the 7s-state of the atom. The lifetime of the isomer in the singly charged ion is 165 sec.

We present a method of indirect measurement of fluid flow in a pipeline by solving the inverse problem of heat transfer using an exact analytic solution of the quasi-stationary boundary value problem of heat transfer and experimental data on the temperature of the fluid at discrete points along the pipe. The theoretical results are tested in an experimental installation and by a numerical calculation of the temperature using the finite element method.

We consider a method for measuring the thermal emissivity of adiabatic heat radiators. We analyze the conditions for which we can achieve maximum measurement accuracy.

We consider an algorithm for determining the weber-ampere characteristics of electrical devices, based on experimental studies and mathematical modeling. To construct the mathematical model, we used the methods of harmonic balance and simplex-optimization.

The present article considers a method of phase comparison of the instantaneous values of the frequencies of quasi-harmonic signals with slowly varying parameters, based on a parametric algorithm for estimation of the lag angle. It is shown that the errors of the method are comparable with the errors of the classical quadrature heterodyne method in comparing signals with constant frequency difference. The advantage of the proposed method lies in a four-fold reduction in the number of computational operations. The theoretical conclusions are supported by numerical and field experiments.

The question of selecting the pitch of an ultrasonic antenna arrays in order to obtain the maximal signalto-structural noise ratio is considered. The ordinary mode of a linear antenna array, in which one of its elements radiates a signal and the other receives a signal, as well as the synthetic aperture mode, and the SAFT-C mode, in which each element in turn radiates a signal and the others receive the signal, are described. It is shown that the SAFT-C mode produces a four-fold increase in the signal-to-structural noise ratio from that achieved in the other modes.