scholarly journals On the modeling of planetary plasma environments by a fully kinetic electromagnetic global model HYB-em

2010 ◽  
Vol 28 (3) ◽  
pp. 743-751 ◽  
Author(s):  
V. Pohjola ◽  
E. Kallio
Keyword(s):  
Magnetic Field ◽  
Kinetic Model ◽  
Electromagnetic Waves ◽  
Dimensional Space ◽  
Spherical Wave ◽  
Three Dimensional ◽  
Magnetized Plasma ◽  
Electromagnetic Model ◽  
The Stability ◽  
Propagation Of Waves

Abstract. We have developed a fully kinetic electromagnetic model to study instabilities and waves in planetary plasma environments. In the particle-in-a-cell (PIC) model both ions and electrons are modeled as particles. An important feature of the developed global kinetic model, called HYB-em, compared to other electromagnetic codes is that it is built up on an earlier quasi-neutral hybrid simulation platform called HYB and that it can be used in conjunction with earlier hybrid models. The HYB models have been used during the past ten years to study globally the flowing plasma interaction with various Solar System objects: Mercury, Venus, the Moon, Mars, Saturnian moon Titan and asteroids. The new stand-alone fully kinetic model enables us to (1) study the stability of various planetary plasma regions in three-dimensional space, (2) analyze the propagation of waves in a plasma environment derived from the other global HYB models. All particle processes in a multi-ion plasma which are implemented on the HYB platform (e.g. ion-neutral-collisions, chemical processes, particle loss and production processes) are also automatically included in HYB-em model. In this brief report we study the developed approach by analyzing the propagation of high frequency electromagnetic waves in non-magnetized plasma in two cases: We study (1) expansion of a spherical wave generated from a point source and (2) propagation of a plane wave in plasma. The analysis shows that the HYB-em model is capable of describing these space plasma situations successfully. The analysis also suggests the potential of the developed model to study both high density-high magnetic field plasma environments, such as Mercury, and low density-low magnetic field plasma environments, such as Venus and Mars.

scholarly journals The Simulation and Optimization of an Electromagnetic Field in a Vertical Continuous Casting Mold for a Large Bloom

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 516
Author(s):  
Lianwang Zhang ◽  
Changjun Xu ◽  
Jiazheng Zhang ◽  
Tao Wang ◽  
Jing Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Continuous Casting ◽  
Electromagnetic Force ◽  
Three Dimensional ◽  
Electromagnetic Stirring ◽  
Current Intensity ◽  
Continuous Casting Mold ◽  
Current Frequency ◽  
Simulation And Optimization ◽  
Electromagnetic Model

The electromagnetic model of a large-bloom continuous casting was established to simulate the magnetic field. The model 3600 digital, high-precision, three-dimensional Gaussian meter was used to measure the internal magnetic field of mold electromagnetic stirring (M-EMS). The distribution of simulated magnetic field was basically consistent with that of the measured magnetic field; the accuracy of electromagnetic stirring model was verified. With the increase of current frequency, the electromagnetic force first increases and then decreases; when the current frequency is 9 Hz, the electromagnetic force reaches its maximum value. A bipolar electromagnetic stirring model is proposed; the influence of current intensity and distance were investigated. With the increase of current intensity of lower mold electromagnetic stirring (M-EMSB), the internal magnetic intensity of upper mold electromagnetic stirring (M-EMSA) gradually increases, and the middle region is gradually filled by magnetic field. With the increase of the distance, the range of the low-intensity magnetic field expands. When the current intensity of the M-EMSB is 320 A, and the distance is 400 mm, an 8 mT uniform magnetic field in the range of 1.2 m is formed. Compared with the traditional continuous casting electromagnetic agitator, the center equiaxial crystal of bipolar electromagnetic agitator increases from 30.3% to 49.5%.

Quaternionic Neural Networks

2009 ◽  
pp. 411-439 ◽  
Author(s):  
Teijiro Isokawa ◽  
Nobuyuki Matsui ◽  
Haruhiko Nishimura
Keyword(s):  
Neural Networks ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Network Models ◽  
Recurrent Network ◽  
Affine Transformations ◽  
Neural Network Models ◽  
Fundamental Properties ◽  
Modern Physics ◽  
The Stability

Quaternions are a class of hypercomplex number systems, a four-dimensional extension of imaginary numbers, which are extensively used in various fields such as modern physics and computer graphics. Although the number of applications of neural networks employing quaternions is comparatively less than that of complex-valued neural networks, it has been increasing recently. In this chapter, the authors describe two types of quaternionic neural network models. One type is a multilayer perceptron based on 3D geometrical affine transformations by quaternions. The operations that can be performed in this network are translation, dilatation, and spatial rotation in three-dimensional space. Several examples are provided in order to demonstrate the utility of this network. The other type is a Hopfield-type recurrent network whose parameters are directly encoded into quaternions. The stability of this network is demonstrated by proving that the energy decreases monotonically with respect to the change in neuron states. The fundamental properties of this network are presented through the network with three neurons.

scholarly journals A Fractional-Order Discrete Noninvertible Map of Cubic Type: Dynamics, Control, and Synchronization

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Xiaojun Liu ◽  
Ling Hong ◽  
Lixin Yang ◽  
Dafeng Tang
Keyword(s):  
Fractional Order ◽  
Initial Conditions ◽  
Dimensional Space ◽  
Equilibrium Points ◽  
Three Dimensional ◽  
State Variables ◽  
Discrete Maps ◽  
The Stability ◽  
Control And Synchronization ◽  
Simultaneous Variation

In this paper, a new fractional-order discrete noninvertible map of cubic type is presented. Firstly, the stability of the equilibrium points for the map is examined. Secondly, the dynamics of the map with two different initial conditions is studied by numerical simulation when a parameter or a derivative order is varied. A series of attractors are displayed in various forms of periodic and chaotic ones. Furthermore, bifurcations with the simultaneous variation of both a parameter and the order are also analyzed in the three-dimensional space. Interior crises are found in the map as a parameter or an order varies. Thirdly, based on the stability theory of fractional-order discrete maps, a stabilization controller is proposed to control the chaos of the map and the asymptotic convergence of the state variables is determined. Finally, the synchronization between the proposed map and a fractional-order discrete Loren map is investigated. Numerical simulations are used to verify the effectiveness of the designed synchronization controllers.

Propagation of electromagnetic waves in circular rods in torsion

1963 ◽  
Vol 255 (1059) ◽  
pp. 389-416 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Induction ◽  
Constitutive Equations ◽  
Electromagnetic Waves ◽  
Linear Functions ◽  
Static Deformation ◽  
Polynomial Functions ◽  
Electric And Magnetic Field ◽  
Speed Of Propagation ◽  
Propagation Of Waves

Invariance considerations are employed to write down constitutive equations governing the propagation of electromagnetic waves in isotropic materials with a centre of symmetry which are subject to a static deformation. It is assumed that the dielectric displacement and magnetic induction vectors are linear functions of the electric and magnetic field intensities, respectively, but are general polynomial functions in the quantities which specify the deformation. The theory is employed to examine propagation along circular cylindrical rods in torsion. Rotating waves are produced whose speed of propagation and rate of rotation depend upon the magnitude of the deformation and the properties of the material. The nature of these waves is examined for the general case where there is no restriction either upon the amount of torsion or upon the magnitude of the effect. When the amount of torsion, or the dependence of the effect upon deformation is small, solutions can be obtained based upon those for the propagation of waves in undeformed materials.

MHD instabilities of a cylindrical plasma with a realistic energy equation

1987 ◽  
Vol 37 (2) ◽  
pp. 175-184 ◽  
Author(s):  
Guidetta Torricelli-Ciamponi ◽  
Vittorio Ciampolini ◽  
Claudio Chiuderi
Keyword(s):  
Magnetic Field ◽  
Time Scales ◽  
Growth Rates ◽  
Thermal Conduction ◽  
Energy Equation ◽  
Magnetized Plasma ◽  
Line Radiation ◽  
Mhd Instabilities ◽  
Solar Plasmas ◽  
The Stability

The influence of a realistic energy equation on the stability of a cylindrical magnetized plasma in a force-free magnetic field is discussed. Thermal conduction, heating and line radiation are included in the treatment. Explicit growth rates for the m = 0 and m = 1 modes are derived and compared with the standard adiabatic or incompressible time-scales. Finally, the relevance of these results for laboratory and solar plasmas is discussed.

CANDU Reactor Space-Time Kinetic Model for Load Following Studies

2010 ◽  
Vol 133 (5) ◽  
Author(s):  
Lingzhi Xia ◽  
Jin Jiang
Keyword(s):  
Kinetic Model ◽  
Neutron Flux ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Space Time ◽  
Reactor Model ◽  
Load Following ◽  
Dimensional Space Time ◽  
Reactor Kinetic ◽  
Reactor Space

This paper presents the development of a three-dimensional space-time neutronic kinetic model of a Canadian deuterium uranium (CANDU) reactor using a modal method. In this method, the reactor space-time neutron flux is synthesized by a time-weighted series of precalculated neutron flux modes. The modes are eigenfunctions of the governing neutron diffusion equation during reference steady-state operation. The xenon effect has also been considered. The reactor model is then implemented within a simulation platform of a CANDU6 reactor regulating system in MATLAB/SIMULINK. A nondimensionalized SIMULINK representation of the reactor kinetic model is established. The behavior of the reactor during load following transients has been simulated using the developed reactor-modeling module. The simulation results prove the efficiency of the model. A three-dimensional neutron flux distribution during transients is represented.

On the stability of parallel flows with parallel magnetic fields

1966 ◽  
Vol 293 (1434) ◽  
pp. 342-358 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Parallel Magnetic Field ◽  
Parallel Flows ◽  
The Mean ◽  
The Stability ◽  
The Magnetic Field ◽  
Parallel Magnetic Fields

The first part of the paper is a physical discussion of the way in which a magnetic field affects the stability of a fluid in motion. Particular emphasis is given to how the magnetic field affects the interaction of the disturbance with the mean motion. The second part is an analysis of the stability of plane parallel flows of fluids with finite viscosity and conductivity under the action of uniform parallel magnetic fields. We show that, in general, three-dimensional disturbances are the most unstable, thus disagreeing with the conclusion of Michael (1953) and Stuart (1954). We show how results obtained for two-dimensional disturbances can be used to calculate the most unstable three-dimensional disturbances and thence we prove that a parallel magnetic field can never completely stabilize a parallel flow.

Convective laser filamentation instability in magnetized plasma

2014 ◽  
Vol 92 (6) ◽  
pp. 504-508 ◽  
Author(s):  
M.S. Bawa’aneh ◽  
Ghada Assayed ◽  
M.R. Said ◽  
S. Al-Awfi
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Amplification Factor ◽  
Magnetized Plasma ◽  
Governing Equations ◽  
Equilibrium Plasma ◽  
Dc Magnetic Field ◽  
Density Values ◽  
Filamentation Instability ◽  
The Magnetic Field

The convective amplification of filamentation instability (FI) of electromagnetic waves traveling along the density ramp of a magnetized plasma is investigated. The generalized amplification factor of the instability in the presence of a DC–magnetic field is derived by obtaining the governing equations of the instability and using the slow-coupling technique to obtain an analytical expression for the amplification factor in weakly magnetized plasma. The result shows enhancement of the convective FI gain by the magnetic field, where the enhancement is stronger for lower equilibrium plasma density values.

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