Correlation of velocities of the waves controlling the thin-plate α-martensite formation and the modulation of the transformation twin structure

For the case of γ-α martensitic transformation (MT) in iron alloys, the concept of transformation twins is developed. As a rule, crystals of α-martensite having the form of thin plates are characterized by a fine twin structure (TS) with interchanging orthogonal directions of main compression axes. An example of the real structures of transformation twins that are not strictly regular is given. It is shown that in dynamic theory of MT the regular TS initiation is associated with coherent propagation of long (ℓ) and short (s) displacement waves belonging to controlling wave process (CWP). An analytical approximation of the dispersion law of s-waves is obtained. The threshold conditions of deformation and the qualitative picture of modulated TS formation are discussed. The correlation of velocities of the waves controlling thin-plate α-martensite crystals formation is established by the example of Fe-30Ni alloy. It is shown that at the real correlation of wave velocities a modulated structure of transformation twins is induced. Such structure contains fragments each of which is connected with the short-wave excited cell. The fragment size is associated with Nbas — the number of layers of the main component inside the TS fragment generated by a single spontaneously activated s-cell. Fragments’ sizes depend on the site of localization of spontaneously appearing s-cell generating the fragment in the area of the CWP front. It is shown that the Nbas value can vary within rather wide limits. Therefore, in contrast to regular TS forming, we should expect repeated s-cells spontaneous excitements for long enough twinned thin-plated crystals. Along with difference of s-and ℓ-waves velocities, consideration of waves (especially s-waves) decay is one more quite determined factor making its contribution into TS modulation. Estimation of this contribution seems to be very actual. © 2017, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved

Method of measurement of electromagnetic radiation from printed circuit board in the near field by spectral-polarization method

© 2017 IEEE. in this paper we propose a technique for estimating the electromagnetic radiation from a printed circuit board in the near field on the basis of the simplest oscillators- Hertz dipoles, the equations for which are well known. This technique makes it possible, at early stages of printed circuit board design, to detect interference emitted from printed circuit board and to estimate their influence on printed circuit board

Use of global ionospheric maps for HF Doppler measurements interpretation

© 2017. The HF Doppler technique, a method of measurement of Doppler frequency shift of ionospheric signal, is one of the well-known and widely used techniques of ionosphere research. It allows investigation of various disturbances in the ionosphere. There are different sources of disturbances in the ionosphere such as geomagnetic storms, solar flashes, meteorological effects and atmospheric waves. The HF Doppler technique allows us to find out the influence of earthquakes, explosions and other processes on the ionosphere, which occurs near the Earth. HF Doppler technique has high sensitivity to small frequency variations and high time resolution but interpretation of results is difficult. In this paper, we attempt to use GPS data for Doppler measurements interpretation. Modeling of Doppler frequency shift variations with use of TEC allows separation of ionosphere disturbances of medium scale

Localization of distributed radiation sources from a printed circuit board in the near field using wavelet transform

© 2018 by IOP Publishing Ltd. In this paper we describe algorithms for localization of distributed radiation sources from a printed circuit board in the near field using wavelet transform. The radiation sources are presented in the form of a set of simple oscillators - Hertz dipoles. Comparison of the two methods of localization for distributed radiation sources using wavelet transform is performed using Tikhonov regularization and LASSO regression. The model examples show that the application of LASSO regression using wavelet transform gives better results

Use of global ionospheric maps for HF Doppler measurements interpretation

© 2017. The HF Doppler technique, a method of measurement of Doppler frequency shift of ionospheric signal, is one of the well-known and widely used techniques of ionosphere research. It allows investigation of various disturbances in the ionosphere. There are different sources of disturbances in the ionosphere such as geomagnetic storms, solar flashes, meteorological effects and atmospheric waves. The HF Doppler technique allows us to find out the influence of earthquakes, explosions and other processes on the ionosphere, which occurs near the Earth. HF Doppler technique has high sensitivity to small frequency variations and high time resolution but interpretation of results is difficult. In this paper, we attempt to use GPS data for Doppler measurements interpretation. Modeling of Doppler frequency shift variations with use of TEC allows separation of ionosphere disturbances of medium scale

Use of global ionospheric maps for HF Doppler measurements interpretation

© 2017. The HF Doppler technique, a method of measurement of Doppler frequency shift of ionospheric signal, is one of the well-known and widely used techniques of ionosphere research. It allows investigation of various disturbances in the ionosphere. There are different sources of disturbances in the ionosphere such as geomagnetic storms, solar flashes, meteorological effects and atmospheric waves. The HF Doppler technique allows us to find out the influence of earthquakes, explosions and other processes on the ionosphere, which occurs near the Earth. HF Doppler technique has high sensitivity to small frequency variations and high time resolution but interpretation of results is difficult. In this paper, we attempt to use GPS data for Doppler measurements interpretation. Modeling of Doppler frequency shift variations with use of TEC allows separation of ionosphere disturbances of medium scale

Optimization of a heralded single-photon source with spatial and temporal multiplexing

© Published under licence by IOP Publishing Ltd. The properties of a heralded single-photon source with temporal and spatial multiplexing are studied with the aim to maximize its efficiency for a given value of the second-order zero-time autocorrelation function. We show that the variable time delay, which is used for temporal multiplexing, can be optimized so that the mean number of photon passes through the switches and the total number of switches are respectively reduced to ∼ log2N and ∼ (1/2)log2N, where N is the temporal multiplexing degree. The total efficiency of such an optimized source is calculated for typical switching losses and the autocorrelation function is calculated in the presence of the detector dark-count noise

Multipulse optical sequences in solid-state photon echo processors

The physical principles of multipulse control of coherent and relaxation processes in solid-state photon echo processors and quantum counters were investigated. The possibility of implementing the technique of narrowing of dipole-broadened spectral lines in optics with the use of multipulse optical sequences (of WAHUHA type) was theoretically considered. © 2007 by Allerton Press, Inc