Two-dimensional resolution in the DOA finding of a single short pulse by the waveform reconstruction technique

2003 ◽  
Vol 86 (12) ◽  
pp. 68-77
Author(s):  
Masanori Ishii ◽  
Takashi Iwasaki
Keyword(s):  
Short Pulse ◽  
Reconstruction Technique ◽  
Two Dimensional

scholarly journals Inverse reconstruction technique based on time-dependent Petschek-type reconnection model: first application to THEMIS magnetotail observations

2009 ◽  
Vol 27 (12) ◽  
pp. 4369-4377
Author(s):  
V. Ivanova ◽  
J. Liu ◽  
S. Kiehas ◽  
V. Semenov ◽  
H. Biernat
Keyword(s):  
Electric Field ◽  
Total Duration ◽  
Time Dependent ◽  
Reconstruction Technique ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Two Dimensional ◽  
Line Position ◽  
Inverse Reconstruction ◽  
Reconnection Model

Abstract. We apply the inverse reconstruction technique based on the two-dimensional time-dependent Petschek-type reconnection model to a dual bipolar magnetic structure observed by THEMIS B probe in the Earth's magnetotail during a substorm on 22 February 2008 around 04:35 UT. The technique exploits the recorded bipolar magnetic field variation as an input and provides the reconnection electric field and the location of the X-line as an output. As a result of the technique application, we get (1) the electric field, reaching ~1.1 mV/m at the maximum and consisting of two successive pulses with total duration of ~6 min, and (2) the approximate X-line position located in the magnetotail between 18 and 20 RE.

scholarly journals Reconstruction of two-dimensional magnetopause structures from Cluster observations: verification of method

2004 ◽  
Vol 22 (4) ◽  
pp. 1251-1266 ◽  
Author(s):  
H. Hasegawa ◽  
B. U. Ö. Sonnerup ◽  
M. W. Dunlop ◽  
A. Balogh ◽  
S. E. Haaland ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Minimum Variance ◽  
Reconstruction Technique ◽  
Current Layer ◽  
Two Dimensional ◽  
Magnetic Islands ◽  
Maximum Variance ◽  
Spacecraft Trajectory ◽  
Shafranov Equation ◽  
Mathematical Techniques

Abstract. A recently developed technique for reconstructing approximately two-dimensional (∂/∂z≈0), time-stationary magnetic field structures in space is applied to two magnetopause traversals on the dawnside flank by the four Cluster spacecraft, when the spacecraft separation was about 2000km. The method consists of solving the Grad-Shafranov equation for magnetohydrostatic structures, using plasma and magnetic field data measured along a single spacecraft trajectory as spatial initial values. We assess the usefulness of this single-spacecraft-based technique by comparing the magnetic field maps produced from one spacecraft with the field vectors that other spacecraft actually observed. For an optimally selected invariant (z)-axis, the correlation between the field components predicted from the reconstructed map and the corresponding measured components reaches more than 0.97. This result indicates that the reconstruction technique predicts conditions at the other spacecraft locations quite well. The optimal invariant axis is relatively close to the intermediate variance direction, computed from minimum variance analysis of the measured magnetic field, and is generally well determined with respect to rotations about the maximum variance direction but less well with respect to rotations about the minimum variance direction. In one of the events, field maps recovered individually for two of the spacecraft, which crossed the magnetopause with an interval of a few tens of seconds, show substantial differences in configuration. By comparing these field maps, time evolution of the magnetopause structures, such as the formation of magnetic islands, motion of the structures, and thickening of the magnetopause current layer, is discussed. Key words. Magnetospheric physics (Magnetopause, cusp, and boundary layers) – Space plasma physics (Experimental and mathematical techniques, Magnetic reconnection)

scholarly journals Resistive MHD reconstruction of two-dimensional coherent structures in space

2010 ◽  
Vol 28 (11) ◽  
pp. 2113-2125 ◽  
Author(s):  
W.-L. Teh ◽  
B. U. Ö. Sonnerup ◽  
J. Birn ◽  
R. E. Denton
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Synthetic Data ◽  
Two Dimensions ◽  
Mhd Equations ◽  
Numerical Code ◽  
Reconstruction Technique ◽  
Two Dimensional ◽  
Geomagnetic Tail ◽  
Spacecraft Spin

Abstract. We present a reconstruction technique to solve the steady resistive MHD equations in two dimensions with initial inputs of field and plasma data from a single spacecraft as it passes through a coherent structure in space. At least two components of directly measured electric fields (the spacecraft spin-plane components) are required for the reconstruction, to produce two-dimensional (2-D) field and plasma maps of the cross section of the structure. For convenience, the resistivity tensor η is assumed diagonal in the reconstruction coordinates, which allows its values to be estimated from Ohm's law, E+v×B=η·j. In the present paper, all three components of the electric field are used. We benchmark our numerical code by use of an exact, axi-symmetric solution of the resistive MHD equations and then apply it to synthetic data from a 3-D, resistive, MHD numerical simulation of reconnection in the geomagnetic tail, in a phase of the event where time dependence and deviations from 2-D are both weak. The resistivity used in the simulation is time-independent and localized around the reconnection site in an ellipsoidal region. For the magnetic field, plasma density, and pressure, we find very good agreement between the reconstruction results and the simulation, but the electric field and plasma velocity are not predicted with the same high accuracy.

scholarly journals Inverse Transient Radiative Analysis in Two-Dimensional Turbid Media by Particle Swarm Optimizations

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Yatao Ren ◽  
Hong Qi ◽  
Qin Chen ◽  
Liming Ruan
Keyword(s):  
Particle Swarm Optimization ◽  
Short Pulse ◽  
Particle Swarm ◽  
Pso Algorithm ◽  
Circular Inclusion ◽  
Turbid Media ◽  
Two Dimensional ◽  
Swarm Optimization ◽  
Time Resolved ◽  
Short Pulse Laser

Three intelligent optimization algorithms, namely, the standard Particle Swarm Optimization (PSO), the Stochastic Particle Swarm Optimization (SPSO), and the hybrid Differential Evolution-Particle Swarm Optimization (DE-PSO), were applied to solve the inverse transient radiation problem in two-dimensional (2D) turbid media irradiated by the short pulse laser. The time-resolved radiative intensity signals simulated by finite volume method (FVM) were served as input for the inverse analysis. The sensitivities of the time-resolved radiation signals to the geometric parameters of the circular inclusions were also investigated. To illustrate the performance of these PSO algorithms, the optical properties, the size, and location of the circular inclusion were retrieved, respectively. The results showed that all these radiative parameters could be estimated accurately, even with noisy data. Compared with the PSO algorithm with inertia weights, the SPSO and DE-PSO algorithm were demonstrated to be more effective and robust, which had the potential to be implemented in 2D transient radiative transfer inverse problems.

Two-dimensional electromagnetic Child–Langmuir law of a short-pulse electron flow

2011 ◽  
Vol 18 (2) ◽  
pp. 023105 ◽  
Author(s):  
S. H. Chen ◽  
L. C. Tai ◽  
Y. L. Liu ◽  
L. K. Ang ◽  
W. S. Koh
Keyword(s):  
Short Pulse ◽  
Electron Flow ◽  
Two Dimensional ◽  
Pulse Electron
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