A model is presented for the increase in magnetoelectric (ME) coupling in magnetostrictive-piezoelectric bilayers in the electromechanical resonance region. The ME voltage coefficients αE have been ...estimated for transverse field orientations corresponding to minimum demagnetizing fields and maximum αE. We solved the equation of medium motion taking into account the magnetostatic and elastostatic equations, constitutive equations, Hooke's law, and boundary conditions. The resonance enhancement of ME voltage coefficient for the bilayer is obtained at antiresonance frequency. To obtain the inverse ME effect, a pick up coil wound around the sample is used to measure the ME voltage due to the change in the magnetic induction in magnetostrictive phase. The measured static magnetic field dependence of ME voltage has been attributed to the variation in the piezomagnetic coefficient for magnetic layer. The frequency dependence of the ME voltage shows a resonance character due to the longitudinal acoustic modes in piezoelectric layer. The model is applied to specific cases of cobalt ferrite–lead zirconate titanate and nickel–lead zirconate titanate bilayers. Theoretical ME voltage coefficients versus frequency profiles are in agreement with data.
The results of studying microphysical and thermodynamic characteristics of tropical convective clouds are presented. The studies included complex experiments on assessing a possibility of artificial ...precipitation enhancement from clouds in the eastern part of Cuba during 1982–1990 and 2005–2007. More than 400 clouds developing over the island and adjoining sea areas are investigated. It is shown that the microphysical and thermodynamic characteristics of the analyzed clouds are closer to continental than marine clouds, which is caused by the effect of aerosol from the surface layer over the island. Based on the results of coupled radar and aircraft studies, a statistical model of changes in cloud parameters is constructed, and the size of the time window is determined, during which clouds meet the criteria of seedability to enhance precipitation: the first 15–20 minutes after the appearance of the first echo.
Sufficient conditions are found for the applicability of the generalized law of the iterated logarithm for sums of dependent random variables in the case where the sequence of normalizing constants ...is not necessarily nondecreasing.
Data found from an experimental study on the possibility of recycling polymer composites on the example of a fiberglass made from a linen fiberglass and an epoxy vinyl ester binder are presented with ...the aim to remove the polymer matrix and obtain a recovered fiberglass not inferior in its properties to the virgin material. The solvolysis method of the composite in a methyldiethanolamine medium is considered. The solvolysis time and the concentration of alkali metal hydroxide in the reaction medium in relation to the strength of recovered glass fibers is established. The solvolysis at a temperature of 180°С and a catalyst concentration of 5% for 6 h was accepted as the optimal regime. As a result, a regime that allowed us to recover fibers with a tensile strength equal to 92% of that of virgin fibers was determined. The recovered fabrics were studied by a thermal analysis and the scanning electron microscopy. GFRP samples were obtained from the recovered fabrics by the VaRTM method. The flexural strength of composites made from the secondary filler was 8.5% lower than that of the same material based on a virgin fabric.
Fast heating of target material by femtosecond laser pulse (fsLP) with duration
τ
L
∼
40
–
100
fs results in the formation of thermomechanically stressed state. Its unloading may cause frontal ...cavitation of subsurface layer at a depth of 50
nm for Al and 100
nm for Au. The compression wave propagating deep into material hits the rear-side of the target with the formation of rarefaction wave. The last may produce cracks and rear-side spallation. Results of MD simulations of ablation and spallation of Al and Au metals under action fsLP are presented. It is shown that the used EAM potentials (Mishin et al. and our new one) predict the different ablation and spallation thresholds on absorbed fluence in Al: ablation
F
a
=
60
{
65
}
mJ/cm
2and spallation
F
s
=
120
{
190
}
mJ/cm
2, where numbers in brackets {
} show the corresponding values for Mishin potential. The strain rate in spallation zone was
4.3
×
1
0
9
1/s at spallation threshold. Simulated spall strength of Al is 7.4{8.7}
GPa, that is noticeably less than 10.3{14}
GPa obtained from acoustic approximation with the use of velocity pullback on velocity profile of free rear surface. The ablation threshold
F
a
≈
120
mJ/cm
2 and crater depth of 110
nm are obtained in MD simulations of gold with the new EAM potential. They agree well with experiment.
Systems with a focused ion beam, using gas field ion sources, are described. The principles of operation and ways of formation of these sources, in which the effective ionization region is determined ...by sizes of a single atom, are considered in the historical context. The described systems have a wide range of applications, both in the field of scanning ion microscopy in combination with various analytical methods and in the field of high-resolution modification of electrical, optical, magnetic, and other properties of materials. This modification, based on ion-induced changes in the structure of material, is most pronounced in crystalline semiconductors, superconductors, and magnets.
The expression for the conductance of a 1D channel, which has been obtained using the well-known exact solution, is analyzed. It is shown that in the case of strong electron—electron interaction, the ...slowest (linear in frequency) asymptotics of the conductance is determined by the behavior of electron—electron interaction in the region of transition from 1D to 3D motion realized near the impurity.
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