共查询到20条相似文献,搜索用时 921 毫秒
1.
The effect of multiple scattering on the decay of high-energy particles has been studied. The self-consistent method for the
calculation of decay rates of particles undergoing multiple elastic collisions in an equilibrium medium has been developed.
Influence of multiple scattering on the decay rate of a neutral pion in a hadron gas has been studied.
Zh. éksp. Teor. Fiz. 116, 3–10 (July 1999) 相似文献
2.
M. V. Bogatyrenko S. I. Bredikhin 《Journal of Experimental and Theoretical Physics》1997,85(2):381-385
A new effect of illumination on ionic conductivity and activation energy of migration of mobile Ag+ cations in RbAg4I5 superionic crystals has been detected and studied. Reversible changes in the ionic conductivity due to illumination of superionic
crystals are caused by reversible changes in the structure of electronic centers caused by elastic strain around these centers.
The effect of elastic deformation on the process of ionic transport and activation energy for diffusion of mobile silver cations
has been studied. Photostimulated recovery of the ionic conductivity after its change due to preliminary illumination of a
RbAg4I5 superionic crystal with light of wavelength λ≃430 nm has been detected. This recovery of the ionic conductivity is due to excitation of centers in complexes generated
by previous illumination of tested samples.
Zh. éksp. Teor. Fiz. 112, 698–706 (August 1997) 相似文献
3.
A. E. Kovalev M. N. Pavlovskii V. M. Bel’skii V. V. Komissarov 《Technical Physics》2001,46(6):686-689
Profiles of elastoplastic shock waves were experimentally revealed in three rocks, namely, in marble (ρ0=2.68 g/cm3), quartzite (ρ0=2.65 g/cm3), and granite (ρ0=2.63 g/cm3). In all these substances, the splittingof the shock-wave front into a leading elastic precursor and a following plastic
compression wave wererevealed. A diffusion of the front of the elastic precursor and a decrease in its amplitude were found
to occur asthe front propagates through the samples of the substances studied. No sharp decrease in the amplitude of elasticwaves
(yielding “tooth”) was fixed. Pressures in the elastic and plastic compression waves, as well as the waveand mass velocities
and the magnitudes of the relative compression were determined. 相似文献
4.
AbstractThe newly synthesised Ba2Sb4GeS10 compound is notable because of the interesting features of the quaternary Sb-containing materials. The first principle method has been used to determine the physical properties of this compound. In particular, the electronic structure has been analysed using both conventional GGA-PBE and HSE06 functional. The values of the band gap for PBE and HSE06 calculations were 1.324 and 1.84 eV, respectively. The calculated elastic constants were used to predict polycrystalline mechanical properties. The estimated Vickers hardness (2.7 GPa) values show that Ba2Sb4GeS10 is soft matter. Moreover, the vibrational properties of the compound have been studied. The calculation of the elastic constants and phonon dispersion curves indicates that the Ba2Sb4GeS10 compound is stable both mechanically and dynamically. Furthermore, the minimum thermal conductivity and optical properties, such as dielectric functions and energy loss function, have also been discussed in detail in this paper. 相似文献
5.
Abstract This paper suggests a classification of texture in quartzitic rocks. Possible mechanisms of texture formation and their relation to tectonic processes are discussed. A scheme for the experimental varification of some models describing the evolution of deformation structures in geological materials in dependence on various erxternal conditions (high pressures, temperatures, various loadings, etc.) acting on a sample is proposed. To investigate “in situ” the mechanisms of texture formation in rocks, high pressure devices are under construction. They will be built of a special Ti ? Zr alloy, which has zero coherent scattering lenght and therefore is well suited for neutron diffraction investigations. Two different devices are proposed. The first one allows neutron diffraction measurements of sample volumes up to 4 cm3, a hydrostatic pressure of 1, 5 GPa, a temperature of 300° C, and uniaxial compression up to 50 kN. Pressure temperature and axial load are measured inside the chamber. Besides during the experiment, diagrams of load, elastic wave velocities and acoustic emission will be recorded. The second chamber is designed to investigate the mechanisms of texture formation in polycrystal samples (rocks or their imitations) at temperatures up to 800° C and axial compression with a force of up to 150 kN. 相似文献
6.
S. A. Gridnev L. P. Safonova O. N. Ivanov T. N. Davydova 《Physics of the Solid State》1998,40(12):1998-2001
The anomalous changes of the low-frequency elastic and inelastic properties of single-crystal (NH4)2SO4 accompanying the phase transition from the paraelectric to the ferroelectric phase have been studied by the reverse torsion-pendulum
method at 223 K and in the temperature region where the spontaneous polarization changes sign.
Fiz. Tverd. Tela (St. Petersburg) 40, 2202–2205 (December 1998) 相似文献
7.
V. L. Golo Yu. M. Evdokimov E. I. Kats 《Journal of Experimental and Theoretical Physics》1997,85(6):1180-1186
Under certain conditions, mechanical forces can cause an anisotropic molecule like DNA to assume a toroidal spatial structure.
A simple model describing such a behavior is suggested. The model incorporates anisotropic elastic energy and external electrical
forces. The steady-state structures formed by a macromolecule have been studied numerically using this model. There exist
ranges of model parameters, namely, the anisotropy of the elastic tensor, magnitude and orientation of forces, and modulation
periods, where molecules have toroidal, spherical, or extended structures. Estimates of parameters characteristic of these
structures are consistent with experimental data. In particular, the toroidal structure dimension corresponds to experimental
dimensions of toroidal globules produced as a result of so-called PSI condensation of DNA molecules.
Zh. éksp. Teor. Fiz. 112, 2156–2168 (December 1997) 相似文献
8.
Shamsan S. Obaid M. I. Sayyed D. K. Gaikwad H. O. Tekin Y. Elmahroug P. P. Pawar 《辐射效应与固体损伤》2013,168(11-12):900-914
ABSTRACTThe photon attenuation coefficients for the rocks (Feldspathic basalt, Compact basalt, Volcanic rock, Pink granite, Sandstone and Dolerite) have been investigated using MCNPX and Geant4 codes for photon energies 122, 356, 511, 662, 1170, 1275 and 1330 keV. Comparison of the simulation and experimental results of mass attenuation coefficients is presented. The exposure buildup factors also have been calculated with the help of the G-P fitting method. The comparison showed reasonable agreement between the simulated and experimental data for all rocks. The results show that sandstone has the highest mean free path as well as exposure buildup factor which signifies that sandstone requires a larger thickness for protection from photons. 相似文献
9.
ABSTRACTThe iridium is an important metal which has excellent resistance to corrosion at high temperature. L12 intermetallic compounds i.e. Ir3Nb and Ir3Zr, with similar lattice parameters are ideal for working at high temperature. They are fully soluble due to their low lattice misfit. A first-principle investigation into the effect of doping Zr with different concentrations on the electronic structure, mechanical and thermodynamic properties of NbIr3 has been studied to prompt the development of novel high-temperature materials. Nine ZrxNb8?xIr24 compounds are carefully considered. The results show that adding Zr into these compounds can strengthen their structural stability and ductility. Nevertheless, it reduces the elastic modulus and elastic stiffness. Simultaneously, with the increase of Zr content, the thermodynamic properties of these compounds decrease. It is also found that the changes of elastic modulus are mainly attributed to the variations of bonds in these compounds. 相似文献
10.
F. Monroy F. Ortega R.G. Rubio 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(4):745-754
The thermoelastic behaviour of polyvinylacetate monolayers spread on an aqueous subphase has been studied using rheological
data previously published (Monroy et al., Phys. Rev. E 58, 7629 (1998)). The results show fluid-like viscoelastic behaviour well above a transition temperature , while at lower temperatures a soft solid-like behaviour emerges. The correlation between thermodynamic and elastic properties
below can be described in terms of scaling laws.
Received 12 January 1999 and Received in final form 11 June 1999 相似文献
11.
Conical refraction, which is due to the renormalization of the elastic moduli by the effective magnetoelastic interaction
and depends on the static magnetic field, has been experimentally observed in an α-Fe2O3 trigonal easy-plane antiferromagnet in addition to the usual internal conical refraction of transverse elastic waves propagating
along the trigonal C
3 axis. It has been shown that the deviation angle θη of the energy flux from the C
3 axis at the internal conical refraction is independent of the magnetic field applied in the basal plane (H ⊥ C
3) and is a constant determined by the ratio of the elastic moduli C
14 and C
44. The deviation angle of the energy flux at the antiferromagnetic conical refraction increases with the magnetic field and
approaches the value θη at large H values. The results are well described by the theory of this phenomenon developed by E.A. Turov and confirm its basic conclusions. 相似文献
12.
A physical model of shock-wave phenomena in metals irradiated by a femtosecond laser pulse has been developed. The use of
the experimental results (reported in S.I. Ashitkov et al., Pis’ma Zh. Eksp. Teor. Fiz. 92, 568 (2010) [JETP Lett. 92, 516 (2010)] together with the molecular dynamics simulation makes it possible to study the elastic properties of aluminum
crystals at extreme shear stresses comparable in amplitude with the shear modulus. As a result, the elastic Hugoniot adiabat
has been continued to the region of metastable elastic states at very high pressures, which are one or two orders of magnitude
higher than the commonly accepted values for the dynamic elastic limit. It has been shown that the ultrashort elastic shock
wave of superhigh pressure precedes the formation of the known split-shock wave structure consisting of an elastic precursor
and a plastic shock wave. 相似文献
13.
K. V. Samokhin 《JETP Letters》1996,64(8):580-585
The friction dynamics of contacting D-dimensional disordered elastic manifolds, driven by external forces, is studied, and the existence of a zero-temperature
depinning transition below some critical dimensionality is demonstrated for different kinds of elastic response. It is shown
that this model falls into the universality class of single interface depinning in a 2D-dimensional random medium.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 8, 532–537 (25 October 1996)
Published in English in the original Russian Journal. Edited by Steve Torstveit. 相似文献
14.
Abstract The effect of geometrical shape of eroding absolutely rigid particles on the threshold rate of failure has been studied. The Shtaerman–Kilchevsky theory of quasi-static blunt impact, which generalizes the Hertzs classical impact theory, is used for modelling the frictionless contact interaction of an axially-symmetric particle with an elastic half-space. The incubation time fracture criterion is applied for predicting surface fracture. It is shown that there exists a critical value of the particle shape parameter such that for all its lower values, the fracture energy possesses a non-zero minimal value. 相似文献
15.
《Waves in Random and Complex Media》2013,23(4):535-552
AbstractTo study the effect of initial stress on the propagation behavior of Love waves in a layered functionally graded piezoelectric structure, a mathematical model is established. The piezoelectric layer is taken as exponentially graded material where as half-space is taken as simply elastic substratum. The coupled electromechanical field equations are solved analytically to obtain the mechanical displacements and electrical potential functions for the piezoelectric layer and elastic substrate. The dispersion relations are obtained for electrically open and short cases. The higher mode Love wave propagation has been considered. For numerical interpretation of the results, four sets of piezoelectric layer and elastic substrate have been taken into consideration. Graphical representation reveals about the effect of initial stress and the effect of inhomogeneity parameter on the phase velocity against wave number for electrically open and electrically short cases, respectively. 相似文献
16.
A time-resolved femtosecond optical pump-probe setup has been combined with a high hydrostatic pressure apparatus to investigate the pressure dependence of the electron and lattice ultrafast response of silver nanoparticles embedded in a glass. The short time scale measurements shows that the time constant of the electron-phonon energy exchange is unchanged over the studied pressure range (up to 60 kbar). The frequency of the coherent acoustic vibration of the nanoparticles observed on a longer time scale is found to linearly increase with pressure in agreement with the metal elastic property changes. The acoustic mode damping is also found to be modified by pressure, suggesting alteration of the metal-glass interface properties. 相似文献
17.
M. M. Hossain 《Molecular physics》2020,118(3)
ABSTRACTTitanium nitride halides, TiNX (X = F, Cl, Br, I) in the α-phase (orthorhombic) are exciting quasi two-dimensional (2D) electronic systems exhibiting a fascinating series of electronic ground states. Pristine TiNX are semiconductors with varying energy gaps and possess attractive properties for potential applications in optoelectronics, photovoltaics, and thermoelectrics. Alkali metal intercalated TiNCl becomes superconducting at reasonably high temperature. We have revisited the electronic band structure of TiNX using density functional theory (DFT) based calculations. The atomic orbital resolved partial electronic energy densities of states are calculated together with the total density of states (TDOS). The structural and elastic properties have been investigated in details for the first time. The elastic anisotropy has been explored. The optical properties of TiNX are studied for the first time. The Debye temperatures have been calculated and the related thermal and phonon parameters are discussed. The calculated physical parameters are compared with existing theoretical and experimental results and showed fair agreement. TiNX are found to reflect electromagnetic radiation strongly in the mid ultraviolet region. The elastic properties show high degree of anisotropy. The effect of halogen atoms on various structural, elastic, electronic, and thermal properties in TiNX are also discussed in detail. 相似文献
18.
In the present work peculiarities of trajectories and energy losses, ranges and profiles of distribution of low-energy different-mass ions channeling in thin single crystals of metals and semiconductors have been thoroughly studied by computer simulation in binary collision approximation. The character of oscillations of channeled-ion trajectories depending on their energies, aiming points from the axis of a channel, kind of interaction potential, crystal lattice type and temperature has been determined. It has been found that, in the case of light ions even at low energy, the main contribution to energy loss is made by inelastic energy losses, whereas for heavy ions, already at E < 10 keV, elastic energy losses exceed inelastic ones. Profiles of the distribution of channeled ions have been calculated depending on crystal lattice type, kind of ions and their energy. 相似文献
19.
E. G. Sheikin 《Technical Physics》1999,44(2):218-221
A theory of the passage of ions in an amorphous material is developed with elastic and inelastic stopping processes taken
into account. Inelastic stopping of ions is studied in the continuous deceleration approximation. Elastic stopping is studied
with allowance for the discrete character of the change in energy and direction of motion of the ions in elastic scattering
by the target atoms. Integral equations are obtained for the total and projected ion ranges. Expressions are obtained for
the probability of a change in ion energy in elastic and inelastic stopping. Calculations of the projected ranges of Cu and
Ga ions in Si and C targets are performed. The computational results agree well with experiment.
Zh. Tekh. Fiz. 69, 93–97 (February 1999) 相似文献
20.
P.I.C. Teixeira 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(3):471-477
A model is proposed for the reorientation dynamics of a confined nematic liquid crystal elastomer, where the effect of crosslinks
is to couple the director to deformations of the elastic matrix. The model combines the (equilibrium) `neo-classical' theory
of liquid crystal rubber elasticity with the simplest time evolution equations for a system described by two coupled, non-conserved
order parameters. Relaxation from an orientation imposed by an electric field is studied as a function of elastic softness,
starting angle, surface pretilt, and the relative mobilities of director and strain. Most importantly, the absence of a `semi-soft'
elastic threshold changes the long-time behaviour of the effective refractive index of the medium from exponential to inverse
power law decay. Predictions are compatible with recent experimental results by Chang, Chien and Meyer [Phys. Rev. E 56, 595 (1997)].
Received 22 June 1998 相似文献