Non-invasive recordings were made of short-latency auditory evoked potentials (SLAEP) in the bottlenose dolphin
Tursiops truncatus
produced in response to paired pulse sound stimuli (conditioning and ...tes stimuli) delivered through transducers in contact with the acoustic window on the lower jaw. Two types of stimulation were used: monaural (both stimuli through one transducer) and dichotic (conditioning and test stimuli delivered through different transducers, one in contact with the right acoustic window and the other in contact with the left acoustic window). The conditioning and test stimuli had the same characteristics; theinterval between them varied over the range 0.15–10 msec. During monaural stimulation, suppression of the test response was the same over the range of intervals 0.15–0.5 msec; the response was recovered on further increases in the interval. In dichotic stimulation, the most marked suppression of the test response occurred at an interval of 0.5 msec, with recovery of responses at shorter and longer intervals. Complete recovery occurred when the interval was shortened to 0.15 msec and lengthened to 2 msec. The significance of these results for the precedence effect and for dolphin biosonar is discussed.
The derivation of a gas-dynamic model of the radiative conductivity of a weakly ionized gas based on an analysis of the electron kinetics is presented. The gas is formed by the impact ionization of ...rarefied air by fast primary electrons. The distribution function of slow secondary electrons is studied by the local numerical solution of the kinetic equation. The revealed properties of the distribution function are used to derive equations for the concentration, drift velocity, and specific energy of slow electrons.
A mathematical model of the thermomechanical effect of penetrating radiation on a microelectronic product is presented. The model is based on the thermoelasticity equations, which are a consequence ...of the quantum kinetic equations for phonons. Heat transfer is described by the law of conservation of energy and the Cattaneo equation, which takes into account the finiteness of the rate of heat propagation. Lattice vibrations are considered in the approximation of the linear theory of elasticity. In general, the model determines the distribution of temperature, energy flow, strain, and stress. Difference schemes for solving model equations are developed. The efficiency of the developed model is verified by solving the problem of thermal shock.
A physical experiment performed to test a mathematical model for the generation of bremsstrahlung by electrons and the formation of an electromagnetic field during its scattering is considered. ...During the experiment, a high-current electron accelerator irradiates the converter target. The resulting bremsstrahlung generates a flux of emission electrons and an electromagnetic field in a sealed chamber. A mathematical model of the measuring circuit used for the experimental determination of the electric current in the chamber is developed. The results of physical and computational experiments simulating them coincide with satisfactory accuracy. It is established that the necessary condition for confirming the model is to take into account the measuring equipment in the computational experiment and use directly measured values for comparison.
Simulation of Gas Ionization by Fast Electrons Berezin, A. V.; Markov, M. B.; Kosarev, O. S. ...
Mathematical models and computer simulations,
2022/8, Letnik:
14, Številka:
4
Journal Article
Recenzirano
The impact ionization of a rarefied gas by high-energy electrons is considered. An approximate hydrodynamic model of the current density of low-energy secondary electrons formed during impact ...ionization is constructed. The concentration, drift velocity, and specific energy are calculated by an approximate solution of the kinetic equation for secondary electrons. Spatial homogeneity, isotropy of the initial distribution of secondary electrons, coincidence of the direction of their drift and the electric field are assumed. Additional approximations are related to the structure of the distribution function of secondary electrons and cross section averaging. The results of model validation by comparison with direct collision simulation are presented.
The features of the use of technical butane in gas supply systems are considered, cri-teria are established to ensure the presence of excess pressure in the tank. A mathematical model of temperature ...distribution on the reservoir contour has been developed, the tempera-tures of technical butane vapor have been calculated, in the presence of heat exchange elements of gas supply systems with the surrounding soil. The thickness of thermal insulation is justified to ensure an overpressure in the tank. The composition of the gas-air mixture, taking into ac-count the restrictions on the fluctuations in the Wobbe number, ensures the complete combus-tion of the mixture in gas-powered consumer installations.
The processes of charge transfer in semiconductors are considered. A model is constructed based on the quantum kinetic equations for the distribution functions of conduction electrons and holes of ...the valence band in the phase space of coordinates and quasi-momenta. Scattering of charge carriers is modeled by the statistical particle method. The basic processes of electron scattering by lattice defects are considered. The calculations of the electron drift velocity in pure and doped silicon are presented.
The frequency resolving power of hearing (FRP) of the beluga whale
Delphinapterus leucas
was studied as dependent on influence of lasting low-intensity sounds (of the ultrasonic range from –20 to +10 ...dB). Testing of the spectrum ripple-phase reversal was used in conjunction with a noninvasive recording of auditory evoked potentials. FRP parameters were found to depend nonmonotonically on the intensity of the background noise. The resultant adaptation effects can be explained by the fact that, in response to the high-intensity signals, the auditory system sensitivity is reduced to the level optimal for analysis of these signals.
In this paper, we consider the conduction current excited in a silicon obstacle by the action of an external flux of penetrating radiation. We use quantum kinetic equations for distribution functions ...of conduction band electrons and holes of the valence band in the phase space of coordinates and quasi-momentums. Effective masses, densities of states, and group velocities of particles are determined on the base of band theory of a crystal. The approximation of the continuous momentum losses due to scattering on lattice defects is performed. The applicability of the model is validated by the comparison with the experimental data for the electron average-velocity dependence on the electric-field strength and on the velocity of the electron-energy transmission to the lattice. The silicon radiation conductivity excited by a free-electron current is calculated and the compliance of the results with the theoretical estimates is demonstrated.
Depth resolution of spectral ripples was measured in normal humans using a phase-reversal test. The principle of the test was to find the lowest ripple depth at which an interchange of peak and ...trough position (the phase reversal) in the rippled spectrum is detectable. Using this test, ripple-depth thresholds were measured as a function of ripple density of octave-band rippled noise at center frequencies from 0.5 to 8 kHz. The ripple-depth threshold in the power domain was around 0.2 at low ripple densities of 4-5 relative units (center-frequency-to-ripple-spacing ratio) or 3-3.5 ripples/oct. The threshold increased with the ripple density increase. It reached the highest possible level of 1.0 at ripple density from 7.5 relative units at 0.5 kHz center frequency to 14.3 relative units at 8 kHz (5.2 to 10.0 ripple/oct, respectively). The interrelation between the ripple depth threshold and ripple density can be satisfactorily described by transfer of the signal by frequency-tuned auditory filters.