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

Toward architecturing of metal composites by twist extrusion

The paper presents a new route for realizing the concept of architecturing of composites by severe plastic deformation. The proposed route involves multi-pass twist extrusion of a composite with fibers. The potential of the method is first illustrated by mathematical modeling and then tested through pilot processing of a composite consisting of a copper matrix and a single aluminum fiber. Metallographic analysis revealed an unexpected shape of the fiber after processing. Finite element simulations were performed to understand the evolution of the fiber shape and to optimize the processing regime for achieving improved reinforcements in twist-extruded composites.1165Ysciescopu

Feasibility of needle and syringe programs in Tajikistan distributing low dead space needles

Background In 2012, the World Health Organization recommended that needle and syringe programs offer their clients low dead space insulin syringes with permanently attached needles. However, in many countries, these syringes are not acceptable to a majority of people who inject drugs. This study assessed the feasibility of working with needle and syringe programs to implement the WHO recommendation using low dead space detachable needles. The study also assessed the acceptability of the needles. Methods Two needle and syringe programs in Tajikistan—one in Kulob and one in Khudjand—received 25,000 low dead space detachable needles each. The programs distributed low dead space detachable needles and a marketing flyer that emphasized the relative advantages of the needles. Each program also enrolled 100 participants, and each participant completed a baseline interview and a 2-month follow-up interview. Results At follow-up, 100% of participants reported trying the low dead space detachable needles, and 96% reported that they liked using the needles. Both needle and syringe programs distributed all their needles within the first 60 days of the project indicating use of the needles, even among clients who did not participate in the study. Conclusions This project demonstrates that it is feasible for needle and syringe programs to offer and promote low dead space needles to their clients. The findings indicate that low dead space needles are acceptable to needle and syringe program clients in these Tajikistan cities. To reduce HIV and hepatitis C virus transmission, needle and syringe programs should offer low dead space needles, low dead space insulin syringes in addition to standard needles, and syringes to their clients

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

Pseudobinary Joins of the LiF-BaF2-AIF3 Ternary System

3LiF · AIF3-BaF2 and 3LiF · AIF3-3BaF2 · 2AIF3 pseudobinary joins of the LiF-BaF2-AIF3 ternary system were studied by DTA and XRD. Calculated and experimental eutectic compositions and temperatures are reported

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