Simulation study of the role of ion kinetics in low- frequency wave train evolution

1995 ◽  
Vol 100 (A2) ◽  
pp. 1779 ◽  
Author(s):  
Bernard J. Vasquez
Keyword(s):  
Simulation Study ◽  
Wave Train ◽  
Low Frequency ◽  
Frequency Wave

scholarly journals Hybrid Simulation Study on Anisotropic Response of Ions to a Low-Frequency Wave in a Field-Reversed Configuration

2019 ◽  
Vol 14 (0) ◽  
pp. 1203064-1203064
Author(s):  
Takahiro URANO ◽  
Toshiki TAKAHASHI ◽  
Akiyoshi HOSOZAWA ◽  
Tomohiko ASAI ◽  
Shigefumi OKADA
Keyword(s):  
Simulation Study ◽  
Low Frequency ◽  
Hybrid Simulation ◽  
Field Reversed Configuration ◽  
Frequency Wave

The Link between Rossby Wave Breakings and Weather Regime Transitions

2011 ◽  
Vol 68 (8) ◽  
pp. 1730-1748 ◽  
Author(s):  
Clio Michel ◽  
Gwendal Rivière
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Western Europe ◽  
Wave Train ◽  
Low Frequency ◽  
The Other ◽  
Western Atlantic ◽  
Frequency Wave ◽  
Weather Regime ◽  
Regime Transitions

Abstract The link between Rossby wave breaking (RWB) and the four wintertime weather regimes over the North Atlantic domain is studied in this paper. Using the 40-yr ECMWF Re-Analysis (ERA-40) data, frequencies of occurrence of anticyclonic and cyclonic wave-breaking (AWB and CWB, respectively) events are computed. Each weather regime has its own characteristic pattern of RWB frequencies. CWB events are found to be most frequent for the Greenland anticyclone weather regime whereas AWB events occur more for the Atlantic ridge and the zonal regimes. Time-lagged composites show that the RWB events characterizing each weather regime occur more often during the formation of the regime rather than during its decay. This suggests a reinforcement of the weather regime by RWB. An exception is the blocking weather regime, which is destroyed by an increase of CWB events south of Greenland. Weather regime transitions are then studied using the low-frequency streamfunction tendency budget. Two types of precursors for the transitions have been identified. One is related to linear propagation of low-frequency transient eddies and the other to nonlinear interactions among the low- and high-frequency transient eddies. The latter has been related to the anomalous frequencies of occurrence of RWB. Two transitions are more precisely analyzed. The transition from blocking to Greenland anticyclone is triggered by a decrease of AWB events over Europe as well as a strong CWB event south of Greenland. The zonal to blocking transition presents evidence of two distinct precursors: one is a low-frequency wave train coming from the subtropical western Atlantic and the other, which occurs later, is characterized by a decrease of AWB and CWB events over western Europe that cannot continue to maintain the westerlies in that region.

The interaction of high-frequency and low-frequency waves in magnetized plasmas

1988 ◽  
Vol 39 (3) ◽  
pp. 369-384 ◽  
Author(s):  
I. V. Relke ◽  
A. M. Rubenchik
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Magnetized Plasmas ◽  
Magnetic Field Fluctuation ◽  
Hamiltonian Description ◽  
Frequency Wave ◽  
Magnetohydrodynamic Waves ◽  
Self Focusing ◽  
Low Frequency Waves

The interaction of high-frequency and low-frequency waves in magnetized plasmas is considered. The narrowness of high-frequency wave packets makes possible a concise Hamiltonian description of the problem. Some concrete problems are studied with the help of the derived equations. The competitive role of scattering in self-consistent density and magnetic-field fluctuation are considered. The self-focusing and solitons of potential plasma waves and magnetohydrodynamic waves are studied.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

scholarly journals High Ripple-Density Resolution for Discriminating Between Rippled and Nonrippled Signals: Effect of Temporal Processing or Combination Products?

2021 ◽  
Vol 25 ◽  
pp. 233121652110101
Author(s):  
Dmitry I. Nechaev ◽  
Olga N. Milekhina ◽  
Marina S. Tomozova ◽  
Alexander Y. Supin
Keyword(s):  
Low Frequency ◽  
Noise Signal ◽  
Density Variation ◽  
Choice Procedure ◽  
Masker Level ◽  
Reference Signals ◽  
Forced Choice Procedure ◽  
The Mean ◽  
Density Resolution

The goal of the study was to investigate the role of combination products in the higher ripple-density resolution estimates obtained by discrimination between a spectrally rippled and a nonrippled noise signal than that obtained by discrimination between two rippled signals. To attain this goal, a noise band was used to mask the frequency band of expected low-frequency combination products. A three-alternative forced-choice procedure with adaptive ripple-density variation was used. The mean background (unmasked) ripple-density resolution was 9.8 ripples/oct for rippled reference signals and 21.8 ripples/oct for nonrippled reference signals. Low-frequency maskers reduced the ripple-density resolution. For masker levels from −10 to 10 dB re. signal, the ripple-density resolution for nonrippled reference signals was approximately twice as high as that for rippled reference signals. At a masker level as high as 20 dB re. signal, the ripple-density resolution decreased in both discrimination tasks. This result leads to the conclusion that low-frequency combination products are not responsible for the task-dependent difference in ripple-density resolution estimates.

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