scholarly journals Mathematical Modeling on Dynamic Characteristics of the Breakdown Process in Narrow-Gap of SF<sub>6</sub> Based on the FCT Algorithm

2019 ◽  
Vol 10 (09) ◽  
pp. 769-783
Author(s):  
Qiuping Zheng ◽  
Dianchun Zheng
Keyword(s):  
Mathematical Modeling ◽  
Dynamic Characteristics ◽  
Narrow Gap ◽  
Breakdown Process

MATHEMATICAL MODELING OF TEMPERATURE EFFECT ON THE FAN CHART OF MAGNETOABSORPTION SPECTRUM IN SEMICONDUCTORS

2019 ◽  
pp. 104-115
Author(s):  
G. Gulyamov ◽  
U. I. Erkaboev ◽  
A. G. Gulyamov
Keyword(s):  
Mathematical Modeling ◽  
Magnetic Field ◽  
Temperature Dependence ◽  
Density Of States ◽  
Landau Levels ◽  
Joint Density ◽  
Narrow Gap ◽  
Narrow Gap Semiconductors ◽  
Dispersion Law ◽  
The Magnetic Field

The article considers the oscillations of interband magneto-optical absorption in semiconductors with the Kane dispersion law. We have compared the changes in oscillations of the joint density of states with respect to the photon energy for different Landau levels in parabolic and non-parabolic zones. An analytical expression is obtained for the oscillation of the combined density of states in narrow-gap semiconductors. We have calculated the dependence of the maximum photon energy on the magnetic field at different temperatures. A theoretical study of the band structure showed that the magnetoabsorption oscillations decrease with an increase in temperature, and the photon energies nonlinearly depend on a strong magnetic field. The article proposes a simple method for calculating the oscillation of joint density of states in a quantizing magnetic field with the non-quadratic dispersion law. The temperature dependence of the oscillations joint density of states in semiconductors with non-parabolic dispersion law is obtained. Moreover, the article studies the temperature dependence of the band gap in a strong magnetic field with the non-quadratic dispersion law. The method is applied to the research of the magnetic absorption in narrow-gap semiconductors with nonparabolic dispersion law. It is shown that as the temperature increases, Landau levels are washed away due to thermal broadening and density of states turns into a density of states without a magnetic field. Using the mathematical model, the temperature dependence of the density distribution of energy states in strong magnetic fields is considered. It is shown that the continuous spectrum of the density of states, measured at the temperature of liquid nitrogen, at low temperatures turns into discrete Landau levels. Mathematical modeling of processes using experimental values of the continuous spectrum of the density of states makes it possible to calculate discrete Landau levels. We have created the three-dimensional fan chart of magneto optical oscillations of semiconductors with considering for the joint density of energy states. For a nonquadratic dispersion law, the maximum frequency of the absorbed light and the width of the forbidden band are shown to depend nonlinearly on the magnetic field. Modeling the temperature  dependence allowed us to determine the Landau levels in semiconductors in a wide temperature spectrum. Using the proposed model, the experimental results obtained for narrow-gap semiconductors are analyzed. The theoretical results are compared with experimental results.

Modified Reynolds Equation for Aerostatic Porous Radial Bearings With Quadratic Forchheimer Pressure-Flow Assumption

2007 ◽  
Author(s):  
Rodrigo Nicoletti ◽  
Zilda C. Silveira ◽  
Benedito M. Purquerio
Keyword(s):  
Mathematical Modeling ◽  
Porous Medium ◽  
Linear Model ◽  
Dynamic Characteristics ◽  
Reynolds Equation ◽  
Dimensional Parameter ◽  
Pressure Flow ◽  
Darcy Model ◽  
Linear Effects ◽  
Modified Reynolds Equation

The mathematical modeling of aerostatic porous bearings, represented by the Reynolds equation, depends on the assumptions for the flow in the porous medium. One proposes a modified Reynolds equation based on the quadratic Forchheimer assumption, which can be used for both linear and quadratic conditions. Numerical results are compared to those obtained with the linear Darcy model. It is shown that, the non-dimensional parameter Φ, related to non-linear effects, strongly affects the bearing dynamic characteristics, but for values of Φ > 10, the results tend to those obtained with the linear model.

A Review on Active Bearings and Perspectives of Using Them in Rotating Machinery

2014 ◽  
Vol 630 ◽  
pp. 181-187
Author(s):  
Denis Shutin ◽  
Leonid Savin ◽  
Alexander Babin
Keyword(s):  
Mathematical Modeling ◽  
Artificial Intelligence ◽  
Control System ◽  
Motion Control ◽  
Dynamic Characteristics ◽  
Rotating Machinery ◽  
Fluid Film ◽  
Motion Control System ◽  
Fluid Film Bearings ◽  
System Components

The paper examines the issues of improving the rotor units by means of using support units with actively changeable characteristics. An overview of the known solutions related to the use of active bearings in various types of turbomachinery is provided. A closer look is given at the design and features of active radial bearings, the main elements of which are fluid film bearings. The results of mathematical modeling of active hybrid bearings are presented. The prospects of the use of this type of supports to improve the dynamic characteristics of rotating machinery, including reducing vibrations caused by various factors, are analyzed. Promising directions of development of active bearings are considered, which primarily involves the modification of system components and rotor motion control system algorithms, including intelligent technologies and artificial intelligence methods.

scholarly journals Research of dynamic characteristics of self-propelled railcars methods of mathematical modeling.

2014 ◽  
Vol 2014 (4) ◽  
pp. 16-19
Author(s):  
Дмитрий Гончаров ◽  
Dmitriy Goncharov ◽  
Владимир Кобищанов ◽  
Vladimir Kobishchanov ◽  
Дмитрий Антипин ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Computer Simulation ◽  
Solid State ◽  
Dynamic Characteristics

On the basis of solid-state computer simulation of the motion of self-propelled railcars &#34;North&#34; performed research parameters of its chassis dynamics. Verification of the results performed in-situ sea trials.

scholarly journals Development of the basic provisions of designing manipulators of mobile robots of special purpose, adapted for robots with dangerous objects

2021 ◽  
Author(s):  
Oksana Yurchyshyn ◽  
Vasyl Strutinsky ◽  
Oleksandr Kravets
Keyword(s):  
Mathematical Modeling ◽  
Mobile Robots ◽  
Dynamic Characteristics ◽  
Static And Dynamic Characteristics

The concept of development of the theory of design of mobile robots for special purposes has been developed. The influence of road conditions on the accuracy of manipulators has been established. Parameters of static and dynamic characteristics of mobile robots are substantiated by means of mathematical modeling. On this basis, Recommendations have been developed, which develop the main provisions of the theory of designing manipulators of mobile robots for special purposes, adapted to work with hazardous objects.

Representation of Asynchronous Motor Dynamics by Generalized Kloss Characteristics

2013 ◽  
Vol 309 ◽  
pp. 113-120
Author(s):  
Eva Riečičiarová ◽  
Tibor Nánási
Keyword(s):  
Mathematical Modeling ◽  
Steady State ◽  
Dynamic Response ◽  
Dynamic Characteristics ◽  
Asynchronous Motor ◽  
Experimental Results ◽  
Dynamic Conditions ◽  
Linear Dynamic ◽  
Sinusoidal Excitation ◽  
Working Point

The paper presents experimental results and mathematical modeling aimed to describe complex machine aggregates working under dynamic conditions. From parameters obtained experimentally the generalized Kloss characteristics is derived for nominal operational speeds of 1,450 min-1, 1,000 min-1 and 750 min-1 under sinusoidal excitation. The steady-state motion is conveniently reinterpreted as an ellipse centered at the working point. Working point is given as the intersection of moment characteristics of the asynchronous motor with the loading characteristics of DC motor with separate excitation. The results of measurements show, that it is necessary to consider the linear dynamic characteristics especially for dynamic response computations near to the resonance.

scholarly journals Theoretical and experimental study of deep soil compaction with a cone reamer

2021 ◽  
Vol 1 (3) ◽  
pp. 60-70
Author(s):  
Kudratullo Z. Tilloev
Keyword(s):  
Mathematical Modeling ◽  
Dynamic Characteristics ◽  
Soil Compaction ◽  
System Analysis ◽  
Surface Deformation ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Road Surface ◽  
Deep Soil ◽  
The Road

Introduction. The road-building machines and mechanisms are always improved depending on the tasks formed in the specific operating conditions of these machines. One of the problems of road construction in difficult climatic conditions is the lack of ground base strength, which results in road surface deformation during operation and periodic traffic restrictions, increasing the cost of maintenance. The road surface annual repair does not fundamentally solve the problem of the roads’ long-term and reliable performance. This problem can be solved by modernizing, for example, a working body for soil compaction based on a crawler excavator. Research aim is to develop a mathematical model for determining the dynamic characteristics of a cone reamer’s effective design to ensure deep compaction of soil foundations for highways and industrial and civil facilities. Research methodology is based on a system analysis of the basic tracked vehicle, the working body, and the compacted soil. The research methods also include mathematical modeling of the cone working body interaction with the soil. Results reliability is confirmed by comparing the results of numerical modeling and experimental studies. The discrepancy between the obtained results of mathematical modeling and laboratory tests in terms of torque and power does not exceed 7–10%. Conclusions. A method for determining the dynamic characteristics of cone devices is developed, and calculation formulas are derived for determining the tilting moment and torque that are applied to the shaft when compacting soils with different characteristics. Experimental studies have been conducted 70 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 3. 2021 ISSN 0536-1028 that have shown the efficiency of this working body. The developed method for determining the dynamic characteristics of cone devices is experimentally confirmed.

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