Time domain dynamics of the asymmetric magnetization reversal in exchange biased bilayers

2005 ◽  
Vol 71 (18) ◽  
Author(s):  
D. M. Engebretson ◽  
W. A. A. Macedo ◽  
Ivan K. Schuller ◽  
P. A Crowell ◽  
C. Leighton
Keyword(s):  
Time Domain ◽  
Magnetization Reversal ◽  
Domain Dynamics

scholarly journals Slow periodic oscillations in time domain dynamics of NO2

2007 ◽  
Vol 126 (7) ◽  
pp. 074301 ◽  
Author(s):  
Michaël Sanrey ◽  
Marc Joyeux
Keyword(s):  
Time Domain ◽  
Periodic Oscillations ◽  
Domain Dynamics

Improving Surface Oscillation Tools Performance Using Time-Domain Dynamics and Torque and Drag Models

2021 ◽  
Author(s):  
Mohamed Mahjoub ◽  
Ngoc-Ha Dao ◽  
Khac-Long Nguyen ◽  
Seif Badri ◽  
Matthew Summersgill ◽  
...  
Keyword(s):  
Time Domain ◽  
Sliding Mode ◽  
Simplified Model ◽  
Full Time ◽  
Surface Oscillation ◽  
Friction Forces ◽  
Substantial Impact ◽  
Rate Of Penetration ◽  
Drag Model ◽  
Domain Dynamics

Abstract Overcoming friction in sliding mode represents a challenging task when drilling an unconventional well with a long lateral section. Among the possible ways to reduce these frictional forces is to use a surface oscillation tool (SOT). By alternating the rotation at surface between the forward and reverse directions, a part of the friction forces is transferred from the axial to tangential direction. Hence, a better transmission of the weight to the drill bit and increased rate of penetration can be achieved. To take full advantage of this tool, an accurate and fast modeling of the influence of its oscillation characteristics is necessary. The SOT is operated at surface by changing its rotation speed and number of wraps in forward and reverse directions. If these characteristics are underestimated, the torsional oscillationsare quickly stopped by the friction moments, and the rate of penetration is not increased enough. However, if they are over estimated, the torsional oscillations can reach the bent motor, and destabilize the tool face orientation (TFO). In this paper, a full time-domain dynamics model and a simplified model coupled with a stiff-string torque and drag model are used to identity the influence length of the SOT, and hence provide an opportunity to optimize its operating parameters. Full and simplified models are compared to each other to ensure their validity. Namely, the effect of the drillstring-wellbore contact distribution is showed to have a substantial impact on the SOT performance. Consequently, it was proved that optimal SOT characteristics Off-Bottom are generally not enough to overcome the friction when drilling. In addition, the torque and drag model is applied to a real case study of an unconventional well with surface and downhole data. It helps provide the driller with a guideline of recommendations on the SOT parameters. These results open some very interesting perspectives in terms of TFO accuracy and slide optimization. The use of modelling in the calibration of the SOT characteristics and the development of the simplified model are both novelties introduced here. This work should lead to significant improvement to extend the length of laterals with steerable mud motor with minimum tortuosity.

Ultrafast Magnetization Reversal Dynamics on A Micrometer-Scale Thin Film Element Studied by Time Domain Imaging

2000 ◽  
Vol 648 ◽  
Author(s):  
B.C. Choi ◽  
G. Ballentine ◽  
M. Belov ◽  
W.K. Hiebert ◽  
M.R. Freeman
Keyword(s):  
Domain Wall ◽  
Time Domain ◽  
Magnetization Reversal ◽  
Switching Time ◽  
Magnetization Vector ◽  
Domain Wall Motion ◽  
Time Resolved ◽  
Imaging Results ◽  
Resonance Frequencies ◽  
The Time Domain

AbstractPicosecond time scale magnetization reversal dynamics in a 15nm thick Ni80Fe20 microstructure (10μm×2μm) is studied using time-resolved scanning Kerr microscopy. The time domain images reveal a striking change in the magnetization reversal mode, associated with the dramatic reduction in switching time when the magnetization vector is pulsed by a longitudinal switching field while a steady transverse biasing field is applied to the sample. According to the time domain imaging results, the abrupt change of the switching time is due to the change in the magnetization reversal mode; i.e., the nucleation dominant reversal process is replaced by domain wall motion if transverse biasing field is applied. Furthermore, magnetization oscillations subsequent to reversal are observed at two distinct resonance frequencies, which sensitively depend on the biasing field strength. The high frequency resonance at f=2 GHz is caused by damped precession of the magnetization vector, whereas another mode at f≈0.8 GHz is observed to arise from domain wall oscillation.

TIME-DOMAIN DYNAMICS OF A THREE-PHASE SLURRY REACTOR

1987 ◽  
Vol 56 (1-6) ◽  
pp. 183-201
Author(s):  
BUM-JONG AHN ◽  
MANUEL LAZARO ◽  
FRANCESC RECASENS
Keyword(s):  
Time Domain ◽  
Slurry Reactor ◽  
Three Phase ◽  
Domain Dynamics

Ultrafast Magnetization Reversal Dynamics Investigated by Time Domain Imaging

2001 ◽  
Vol 86 (4) ◽  
pp. 728-731 ◽  
Author(s):  
B. C. Choi ◽  
M. Belov ◽  
W. K. Hiebert ◽  
G. E. Ballentine ◽  
M. R. Freeman
Keyword(s):  
Time Domain ◽  
Magnetization Reversal ◽  
Ultrafast Magnetization

scholarly journals Time-domain dynamics of reverse saturable absorbers with application to plasmon-enhanced optical limiters

Nanophotonics ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 145-151 ◽  
Author(s):  
Shaimaa I. Azzam ◽  
Alexander V. Kildishev
Keyword(s):  
Time Domain ◽  
Optical Switching ◽  
Rate Equations ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Saturable Absorbers ◽  
Metal Grating ◽  
Full Wave ◽  
Optical Limiters ◽  
Domain Dynamics

AbstractAn advanced full-wave time-domain numerical model for reverse saturable absorption (RSA) is presented and verified. Rate equations describing atomic relaxations and excitation dynamics are coupled to the Maxwell equations by using a Lorentzian oscillator, which models the kinetics-dependent light–matter interactions. The presented novel technique provides a versatile multiphysics framework for designing complex structures and integrating diverse material models that were not previously possible. The multiphysics framework allows capturing the behavior of the RSA materials embedded in artificial photonic nanostructures that cannot be analyzed with established techniques such as the Beer–Lambert law. To showcase the importance of the full-wave RSA analysis coupled to carrier kinetics, we analyze two plasmon-enhanced optical limiters: a metal grating and a Fabry–Perot cavity-like structure where we decrease the unenhanced limiter threshold by a factor of 3 and 13, respectively. This is a promising approach for developing RSA devices operating at reduced illumination levels and thereby significantly expanding their area of applicability to areas such as protective eyewear and automatically dimmed windows. By exploring the dynamic behavior of a given RSA system, this framework will provide critical insights into the design of transformative photonic devices and their complementary optical characterization, and serve as an invaluable utility for guiding the development of synthetic absorbing materials. We believe that our multiphysics models are crucial enabling tools that lay a necessary foundation for the numerical machinery required for the realization and optimization of optical limiting and all-optical switching systems.

scholarly journals Time-domain dynamics of saturation of absorption using multilevel atomic systems

2018 ◽  
Vol 8 (12) ◽  
pp. 3829 ◽  
Author(s):  
Shaimaa I. Azzam ◽  
Alexander V. Kildishev
Keyword(s):  
Time Domain ◽  
Atomic Systems ◽  
Domain Dynamics

scholarly journals Near-Field Imaging and Time-Domain Dynamics of Photonic Topological Edge States in Plasmonic Nanochains

Nano Letters ◽  
2021 ◽  
Author(s):  
Qiuchen Yan ◽  
En Cao ◽  
Quan Sun ◽  
Yutian Ao ◽  
Xiaoyong Hu ◽  
...  
Keyword(s):  
Time Domain ◽  
Near Field ◽  
Edge States ◽  
Near Field Imaging ◽  
Domain Dynamics ◽  
Field Imaging
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