Technical Physics Letters最新文献

Abstract

A method for constructing models of the scenario simulation of special situations in biophysical systems with allowance for the effect of changes in the physics of the Sun is proposed. Tools for representing hybrid computational structures for computer models of scenarios of invasion of species with a high reproductive potential into a new habitat by analogy with physical phase transitions are being intentionally developed. Our analysis shows that the dynamics of population insect invasions has much in common with the development of the modern pandemic: many series of repeated activity outbreaks are observed in both forest pests and new strains of coronavirus. After a long, but false and deceptive, damping, local peaks reappear, as has been observed for the invasive North American Lymantria dispar moth pest. Physical models of oscillators need to be significantly improved, since biosystems are self-regulating. We have formed a calculation scheme from variants of the right-hand sides of differential equations with predicates for their situational switching at the event transformation points. We have simulated the extreme development and analyzed options in the sequence of stages of crisis processes. The developed invasion modeling principle is based on the description of stages and phase changes during the evolution of processes occurring under the dispersal of alien species. We have developed switching schemes for a set of forms for the right-hand sides of the equations correlated with the invasion stages. The modeled process is divided into stages: introduction of a small group of individuals, hidden existence, adaptive takeover of a habitat, population explosion, crisis, and new oscillating equilibrium. There is a hypothesis that changes in the pest population are influenced by the physical effect of cyclic solar activity. Computer-simulation experiments in scenarios for situations of pulsating pest invasions include the factor of periodic changes in the solar constant, for example, in the Hale cycle. The factor of cyclicity of the solar constant, according to the Schatten’s model, has been included in the auxiliary equation of our hybrid system. Using the method for organizing hybrid structures, we have studied the phase variants of the invasive phenomena leading to pulsating outbreaks of the Lymantria dispar pest. Analysis of the hybrid model with a lag argument does not allow us to say that the periodic solar activity is the most important physical factor in triggering pulsating outbreaks. The rates of biota recovery and adaptation of natural enemies are more important factors of triggering the outbreak activity.

Abstract

The modern physics of condensed matter, chemistry, and biology deal with quite a large number of systems that are modeled by 1D and 2D oscillatory double-well potentials of variable topology, the parameters of which can change in an external electric field. In solving quantum problems, an exact analytical solution of the Schrödinger equation can only be obtained for a limited number of models (a well with infinite walls, a quantum oscillator, a hydrogen atom, a cubic parabola potential, a double-well oscillator, and some others). When studying a double-well oscillator potential, which simulates the low-temperature chemical kinetics, tunneling transport in structures with quantum dots (QDs) and quantum molecules and another analytical solution to the Schrödinger equation can only be found under the zero temperature condition and the assumption of the absent interaction of tunneling particles with a medium‒thermostat matrix. If these parameters are taken into account, the Schrödinger equation cannot be solved analytically within the conventional quantum-mechanical approach. In the semiclassical approximation (when the de Broglie wavelength of a tunneling particle is significantly shorter than the subbarrier length), using the instanton method, one can analytically determine the tunneling probability. This was first done by the pioneers of the science of quantum tunneling with dissipation: Acad. of the Russian Academy of Sciences A.I. Larkin, Prof. Yu.N. Ovchinnikov (Landau Institute for Theoretical Physics, Russian Academy of Sciences), and winner of the Nobel Prize in Physics (2003) Prof. A.J. Leggett et al. when modeling Josephson contacts with a cubic parabola potential [1, 2, 11]. A.A. Ovchinnikov, Yu.I. Dakhnovsky, and M.B. Semenov [11] were the first to obtain an analytical solution for a 1D double-well oscillatory potential within this theory when modeling low-temperature chemical reactions as tunnel systems with dissipation.

Abstract

Modern industry requires that the surface layers of bearing components made of ShKh15 steel be modified to increase their service life. This effect is obtained by enhancing the microhardness. Currently, the pulsed plasma flow treatment method is being intensively studied. The applicability of this method to bearing steel is limited by high requirements for the surface roughness of manufactured products. In this work, the effect of pulsed plasma flow treatment modes on the roughness and microhardness of ShKh15 steel at different thermal loads and numbers of pulses is studied. The goal was to determine the optimum treatment parameters for obtaining a combination of the maximum hardening with the minimum roughness change. According to the results obtained, after pulsed plasma flow treatment at certain parameters, a fourfold increase in microhardness can be achieved. In addition, when the melting threshold is reached, the roughness of the samples sharply grows. In addition, a series of experiments has been carried out to determine the impact of a number of pulses on the investigated characteristics. It has been found that, under irradiation of ShKh15 steel by several pulses, an increase in the number of impacts on the material provokes a decrease in the microhardness due to a change in the quantitative ratio between the phases. The roughness index varies within 10‒40%, while the values fluctuate chaotically.

Abstract

The influence of uniaxial elastic strain of the Ni lattice on the intensity of mutual diffusion at a solid–liquid contact of Ni and Al has been studied by the molecular dynamics method. In all the cases under consideration, the intensity of diffusion has been found to increase and decrease upon extension and compression, respectively, which is related to a corresponding change in the free volume affecting to a great extent the diffusion mobility of atoms. It has been established that the intensity of mutual diffusion in the case of the (111) interface orientation relative to the Ni lattice is higher in comparison with the (001) orientation. This difference is explained by the different energies of Ni atoms in the aluminum phase and incorporated in the interface of crystalline nickel for both cases.

Abstract—A specialized isotope mass spectrometer for determining the isotopic ratio of lithium by ERIAD (electrospray with atomization in an ion source) is described. The device uses a Matthauch–Herzog-type mass analyzer with double focusing to use ion beams with a large spread in energy and simultaneous registration of signals of both lithium isotopes (⁶Li and ⁷Li), and a two-channel receiver based on a doublet of microchannel plates. The gas-dynamic interface is built according to the Kontorowitz–Gray scheme; from the gas-dynamic point of view, it is “Jong”, that is, the distance between the nozzle and the skimmer is 4 times the size of the “Mach barrel” at the operating pressure (200 Pa). The device is desktop, its weight does not exceed 20 kg. The measurement time is 1000 s, sample replacement time is 100 s, measurement accuracy is ~0.1%.