Numerical Calculations

2013 ◽  
pp. 73-78
Author(s):  
Andrey Grozin
Keyword(s):  
Numerical Calculations

COMPARISON BETWEEN EXPERIMENTS AND NUMERICAL CALCULATIONS ON S = 1/2 HEISENBERG-XY FERROMAGNETIC CHAINS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1451-C8-1452 ◽  
Author(s):  
K. Kopinga ◽  
J. Emmen ◽  
G. C. de Vries ◽  
L. F. Lemmens ◽  
G. Kamieniarz
Keyword(s):  
Numerical Calculations

The Feasibility of Numerical Calculations of Vias Using the Matrix-Penciled Moment Method

PIERS Online ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 36-40 ◽  
Author(s):  
Hailiang Li ◽  
Yu Tian ◽  
Tong Ling
Keyword(s):  
Moment Method ◽  
Numerical Calculations ◽  
The Matrix

Normal form method in search for periodic solutions of ordinary differential equations. Case of the fourth order

2018 ◽  
pp. 24-34
Author(s):  
V. F. Edneral ◽  
O. D. Timofeevskaya
Keyword(s):  
Normal Form ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Periodic Solutions ◽  
Fourth Order ◽  
Numerical Solutions ◽  
Numerical Calculations ◽  
Computational Time ◽  
Resonant Normal Form ◽  
Normal Form Method

Introduction:The method of resonant normal form is based on reducing a system of nonlinear ordinary differential equations to a simpler form, easier to explore. Moreover, for a number of autonomous nonlinear problems, it is possible to obtain explicit formulas which approximate numerical calculations of families of their periodic solutions. Replacing numerical calculations with their precalculated formulas leads to significant savings in computational time. Similar calculations were made earlier, but their accuracy was insufficient, and their complexity was very high.Purpose:Application of the resonant normal form method and a software package developed for these purposes to fourth-order systems in order to increase the calculation speed.Results:It has been shown that with the help of a single algorithm it is possible to study equations of high orders (4th and higher). Comparing the tabulation of the obtained formulas with the numerical solutions of the corresponding equations shows good quantitative agreement. Moreover, the speed of calculation by prepared approximating formulas is orders of magnitude greater than the numerical calculation speed. The obtained approximations can also be successfully applied to unstable solutions. For example, in the Henon — Heyles system, periodic solutions are surrounded by chaotic solutions and, when numerically integrated, the algorithms are often unstable on them.Practical relevance:The developed approach can be used in the simulation of physical and biological systems.

scholarly journals Experimental and CFD Simulations of the Aerosol Flow in the Air Ventilating the Underground Excavation in Terms of SARS-CoV-2 Transmission

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4743
Author(s):  
Tomasz Janoszek ◽  
Zbigniew Lubosik ◽  
Lucjan Świerczek ◽  
Andrzej Walentek ◽  
Jerzy Jaroszewicz
Keyword(s):  
Numerical Calculations ◽  
Mining Institute ◽  
Ventilation Network ◽  
Underground Excavation ◽  
In Situ Tests ◽  
Ansys Fluent ◽  
Aerosol Emission ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

The paper presents the results of experimental and model tests of transport of dispersed fluid droplets forming a cloud of aerosol in a stream of air ventilating a selected section of the underground excavation. The excavation selected for testing is part of the ventilation network of the Experimental Mine Barbara of the Central Mining Institute. For given environmental conditions, such as temperature, pressure, relative humidity, and velocity of air, the distribution of aerosol droplet changes in the mixture of air and water vapor along the excavation at a distance was measured at 10 m, 25 m, and 50 m from the source of its emission. The source of aerosol emission in the excavation space was a water nozzle that was located 25 m from the inlet (inlet) of the excavation. The obtained results of in situ tests were related to the results of numerical calculations using computational fluid dynamics (CFD). Numerical calculations were performed using Ansys-Fluent and Ansys-CFX software. The dimensions and geometry of the excavation under investigation are presented. The authors describe the adopted assumptions and conditions for the numerical model and discuss the results of the numerical solution.

Terahertz response of dl-alanine: experiment and theory

2021 ◽  
Vol 23 (1) ◽  
pp. 657-665
Author(s):  
T. J. Sanders ◽  
J. L. Allen ◽  
J. Horvat ◽  
R. A. Lewis
Keyword(s):  
Large Scale ◽  
Numerical Calculations ◽  
Molecular Vibrations

Numerical calculations and experiments have identified large-scale molecular vibrations leading to unique terahertz spectral absorptions observed in dl-alanine.

scholarly journals On a possibility of transfer of asteroids from the 2:1 mean motion resonance with Jupiter to the Centaur zone

2021 ◽  
Author(s):  
Kazantsev Anatolii ◽  
Kazantseva Lilia
Keyword(s):  
Terrestrial Planet ◽  
Numerical Calculations ◽  
Asteroid Belt ◽  
Time Interval ◽  
Transfer Time ◽  
Mean Motion ◽  
Resonant Orbits ◽  
Main Asteroid Belt ◽  
Absolute Magnitudes ◽  
Mean Motion Resonance

ABSTRACT The paper analyses possible transfers of bodies from the main asteroid belt (MBA) to the Centaur region. The orbits of asteroids in the 2:1 mean motion resonance (MMR) with Jupiter are analysed. We selected the asteroids that are in resonant orbits with e > 0.3 whose absolute magnitudes H do not exceed 16 m. The total number of the orbits amounts to 152. Numerical calculations were performed to evaluate the evolution of the orbits over 100,000-year time interval with projects for the future. Six bodies are found to have moved from the 2:1 commensurability zone to the Centaur population. The transfer time of these bodies to the Centaur zone ranges from 4,600 to 70,000 yr. Such transfers occur after orbits leave the resonance and the bodies approach Jupiter Where after reaching sufficient orbital eccentricities bodies approach a terrestrial planet, their orbits go out of the MMR. Accuracy estimations are carried out to confirm the possible asteroid transfers to the Centaur region.

scholarly journals Magnetic field amplification in newly-born neutron stars

1996 ◽  
Vol 160 ◽  
pp. 435-436
Author(s):  
H.-J. Wiebicke ◽  
U. Geppert
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Gravitational Collapse ◽  
Dipole Field ◽  
Numerical Calculations ◽  
Selection Effects ◽  
Thermoelectric Effects ◽  
Field Amplification ◽  
Seed Field ◽  
Flux Conservation

AbstractWe present a scenario of magnetic field (MF) evolution of newly-born neutron stars (NSs). Numerical calculations show that in the hot phase of young NSs the MF can be amplified by thermoelectric effects, starting from a moderately strong seed-field. Therefore, there is no need to assume a 1012G dipole field immediately after the gravitational collapse of the supernova (SN) event. The widely accepted scenario for such a field to be produced by flux conservation during the collapse is critically discussed. Instead, it can be generated by amplification and selection effects in the first 104yrs, and by the subsequent fast ohmic decay of higher multipole components, when the NS cools down.

scholarly journals Dynamical Evolution of Globular Clusters After Core Collapse

1985 ◽  
Vol 113 ◽  
pp. 139-160 ◽  
Author(s):  
Douglas C. Heggie
Keyword(s):  
Surface Density ◽  
Globular Clusters ◽  
Stellar System ◽  
Dynamical Evolution ◽  
Theoretical Models ◽  
Numerical Calculations ◽  
Core Collapse ◽  
Density Profiles ◽  
The Core ◽  
Fokker Planck

This review describes work on the evolution of a stellar system during the phase which starts at the end of core collapse. It begins with an account of the models of Hénon, Goodman, and Inagaki and Lynden-Bell, as well as evaporative models, and modifications to these models which are needed in the core. Next, these models are related to more detailed numerical calculations of gaseous models, Fokker-Planck models, N-body calculations, etc., and some problems for further work in these directions are outlined. The review concludes with a discussion of the relation between theoretical models and observations of the surface density profiles and statistics of actual globular clusters.

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