Low-frequency component electric microfield distributions in plasmas governed by W. Ebeling potential

2021 ◽  
Author(s):  
Sara Kobbi ◽  
Salima Guerricha ◽  
Smaïl Chihi ◽  
Abdallah Bekkouche ◽  
Mohammed Tayeb Meftah
Keyword(s):  
Low Frequency ◽  
Frequency Component

The Lightning Electromagnetic Pulse Coupling Effect Inside the Shielding Enclosure With Penetrating Wire

Frequenz ◽  
2017 ◽  
Vol 71 (11-12) ◽  
Author(s):  
Xue Jiao ◽  
Bo Yang
Keyword(s):  
Electromagnetic Pulse ◽  
Coupling Effect ◽  
Fdtd Method ◽  
Current Source ◽  
Low Frequency ◽  
Frequency Component ◽  
Lightning Current ◽  
Proper Size ◽  
Practical Engineering ◽  
Difference Time

AbstractTo study the lightning electromagnetic pulse (LEMP) coupling and protection problems of shielding enclosure with penetrating wire, we adopt the model with proper size which is close to the practical engineering and the two-step finite-difference time-domain (FDTD) method is used for calculation in this paper. It is shown that the coupling voltage on the circuit lead inside the enclosure increases about 34 dB, when add 1.0 m long penetrating wire at the aperture, comparing with the case without penetrating wire. Meanwhile, the waveform, has the same wave outline as the lightning current source, shows that the penetrating wire brings a large number of low frequency component into the enclosure. The coupling effect in the enclosure will reduce greatly when penetrating wire has electrical connection with the enclosure at the aperture and the coupling voltage increase only about 12 dB than the case without penetrating wire. Moreover, the results show that though the waveguide pipe can reduce the coupling effect brought by the penetrating wire, the exposing part of penetrating wire can increase the coupling when the penetrating wire outside the enclosure is longer than the waveguide pipe and the longer the exposing part is, the stronger the coupling is.

scholarly journals Electron acoustic solitons in the Earth's magnetotail

2004 ◽  
Vol 11 (2) ◽  
pp. 215-218 ◽  
Author(s):  
S. G. Tagare ◽  
S. V. Singh ◽  
R. V. Reddy ◽  
G. S. Lakhina
Keyword(s):  
Electron Beam ◽  
Small Amplitude ◽  
Low Frequency ◽  
Frequency Component ◽  
Magnetized Plasma ◽  
Cold Electron ◽  
Ion Plasma ◽  
Electron Acoustic ◽  
Two Temperature ◽  
Perpendicular Polarization

Abstract. Small amplitude electron - acoustic solitons are studied in a magnetized plasma consisting of two types of electrons, namely cold electron beam and background plasma electrons and two temperature ion plasma. The analysis predicts rarefactive solitons. The model may provide a possible explanation for the perpendicular polarization of the low-frequency component of the broadband electrostatic noise observed in the Earth's magnetotail.

scholarly journals The Tangential Force Affecting the Radial Baffles in a Stirred Vessel: Analysis of the Macro-instability Related Component

10.14311/450 ◽  
2003 ◽  
Vol 43 (4) ◽  
Author(s):  
P. Hasal ◽  
I. Fořt ◽  
J. Kratěna
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Tangential Force ◽  
Low Frequency ◽  
Frequency Component ◽  
Relative Magnitude ◽  
Tangential Component ◽  
Vertical Position ◽  
Total Force ◽  
Rushton Turbine

Experimental data obtained by measuring the tangential component of the force affecting radial baffles in a flat-bottomed cylindrical mixing vessel stirred with a Rushton turbine impeller is analysed. Spectral analysis of the experimental data demonstrated the presence of its macro-instability (MI) related low-frequency component embedded in the total force. Two distinct dimensionless frequencies (both directly proportional to the impeller speed of rotation N) of the occurence of the MI component were detected: a lower frequency of approximately 0.025N and a higher frequency of about 0.085N. The relative magnitude QMI of the MI-related component of the total tangential force was evaluated by a combination of proper orthogonal decomposition (POD) and spectral analysis. The values of magnitude QMI varied in the interval [rom approximately 0.05 to 0.30. The magnitude QMI takes maximum values at low Reynolds number values (in laminar and transitional regions). In the turbulent region (ReM >20000) the QMI value is low and practically constant. The dependence oj the QMI values on vertical position in the vessel is only marginal. The results suggest that the magnitude of the MI component of the force is significantly influenced by the liquid viscosity and density.

scholarly journals Impaired vagal activity to meal in patients with functional dyspepsia and delayed gastric emptying

2017 ◽  
Vol 46 (2) ◽  
pp. 792-801 ◽  
Author(s):  
W-J Guo ◽  
S-K Yao ◽  
Y-L Zhang ◽  
S-Y Du ◽  
H-F Wang ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Gastric Emptying ◽  
Functional Dyspepsia ◽  
Delayed Gastric Emptying ◽  
Low Frequency ◽  
Treatment Method ◽  
Frequency Component ◽  
High Frequency Component ◽  
Vagal Activity ◽  
Nervous Function

Objective This study was performed to investigate impaired vagal activity to meal in patients with functional dyspepsia (FD) with delayed gastric emptying (GE). Methods Eighty-five patients were studied. GE parameters, including those in the overall and proximal stomach, were measured by GE functional tests at the Department of Nuclear Medicine. Autonomic nervous function was tested by spectral analysis of heart rate variability (HRV). The vagal activity and sympathetic activity were analyzed by recording the power in the high-frequency component (HF), low-frequency component (LF), and LF/HF ratio. Results Overall and proximal GE were delayed in 47.2% and 50.9% of the patients, respectively. Spectral analysis of HRV showed that the HF in patients with delayed proximal GE was significantly lower and that the LF/HF ratio was significantly higher than those in patients with normal proximal GE after a meal. Conclusion Delayed proximal GE might be caused by disrupted sympathovagal balance as a result of decreased vagal activity after a meal. Improvement in vagal activity may constitute an effective treatment method for patients with FD.

The Influence of Air-Bearing Surface Geometry on the Dynamics of Sliders

1992 ◽  
Vol 114 (1) ◽  
pp. 26-31 ◽  
Author(s):  
M. Suk ◽  
T. Ishii ◽  
D. Bogy
Keyword(s):  
Surface Defect ◽  
Laser Interferometer ◽  
Low Frequency ◽  
Frequency Component ◽  
Flying Height ◽  
Disk Drives ◽  
Bearing Surface ◽  
Surface Geometry ◽  
Spacing Variation ◽  
Slider Motion

We investigate the influence of crown on slider dynamics during the takeoff stages of disk drives using the multi-channel laser interferometer. We show that a two-dimensional analysis of slider dynamics during takeoff/landing cannot explain all the observed phenomena. We also examine the crown effect on slider motion while it is flying on a thin film disk with a crater-like surface defect. Finally, we measure the spacing variation of the slider as a function of disk speed. It is observed that the initial motion of negative crown sliders during takeoff can be quite similar to positive crown sliders, although the process is quite different. Furthermore, the results suggest that the negative crown sliders may lead to more disk wear due to longer sliding distances. We observed that during steady flying conditions the craterlike surface defect on the disk produced significantly larger motions for negative crown sliders than positive crown sliders. Lastly, we found that both the waveform and magnitude of the low frequency component of the spacing fluctuation is independent of the slider flying height.

Research on Combined Prediction Model for Busy Telephone Traffic

2014 ◽  
Vol 610 ◽  
pp. 789-796
Author(s):  
Jiang Bao Li ◽  
Zhen Hong Jia ◽  
Xi Zhong Qin ◽  
Lei Sheng ◽  
Li Chen
Keyword(s):  
Prediction Model ◽  
Prediction Accuracy ◽  
Low Frequency ◽  
Prediction Method ◽  
Pso Algorithm ◽  
Frequency Component ◽  
Least Square ◽  
High Frequency Component ◽  
Support Vector ◽  
Telephone Traffic

In order to improve the prediction accuracy of busy telephone traffic, this study proposes a busy telephone traffic prediction method that combines wavelet transformation and least square support vector machine (lssvm) model which is optimized by particle swarm optimization (pso) algorithm. Firstly, decompose the pretreatment of busy telephone traffic data with mallat algorithm and get low frequency component and high frequency component. Secondly, reconfigure each component and use pso_lssvm model predict each reconfigured one. Then the busy telephone traffic can be achieved. The experimental results show that the prediction model has higher prediction accuracy and stability.

scholarly journals Influence of the 2015–2016 El Niño on the record-breaking mangrove dieback along northern Australia coast

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Abhik ◽  
Pandora Hope ◽  
Harry H. Hendon ◽  
Lindsay B. Hutley ◽  
Stephanie Johnson ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Multiple Linear Regression Model ◽  
Frequency Component ◽  
Enso Cycle ◽  
Northern Australia ◽  
Climate Conditions

AbstractThis study investigates the underlying climate processes behind the largest recorded mangrove dieback event along the Gulf of Carpentaria coast in northern Australia in late 2015. Using satellite-derived fractional canopy cover (FCC), variation of the mangrove canopies during recent decades are studied, including a severe dieback during 2015–2016. The relationship between mangrove FCC and climate conditions is examined with a focus on the possible role of the 2015–2016 El Niño in altering favorable conditions sustaining the mangroves. The mangrove FCC is shown to be coherent with the low-frequency component of sea level height (SLH) variation related to the El Niño Southern Oscillation (ENSO) cycle in the equatorial Pacific. The SLH drop associated with the 2015–2016 El Niño is identified to be the crucial factor leading to the dieback event. A stronger SLH drop occurred during austral autumn and winter, when the SLH anomalies were about 12% stronger than the previous very strong El Niño events. The persistent SLH drop occurred in the dry season of the year when SLH was seasonally at its lowest, so potentially exposed the mangroves to unprecedented hostile conditions. The influence of other key climate factors is also discussed, and a multiple linear regression model is developed to understand the combined role of the important climate variables on the mangrove FCC variation.

scholarly journals STORM INDUCED PERIODICITIES OF SUSPENDED SAND MOVEMENT

1978 ◽  
Vol 1 (16) ◽  
pp. 105 ◽  
Author(s):  
Jay E. Leonard ◽  
Benno M. Brenninkmeyer
Keyword(s):  
Surf Zone ◽  
Normal Wave ◽  
Low Frequency ◽  
Sediment Concentration ◽  
Frequency Component ◽  
High Frequency Component ◽  
Computational Technique ◽  
Electromagnetic Current ◽  
Discrete Fourier Analysis ◽  
Sediment Movement

An array of electronic sensors was installed on Nauset Light Beach, Cape Cod, Massachusetts, U.S.A., in order to provide a description of the sediment movement during storm conditions. These sensors included two sediment concentration indicators (almometers) which monitor sediment movement as a function of elevation and time, one bidirectional electromagnetic current meter, and a resistive wave staff. Prior field studies performed during "normal" conditions have indicated that surf-zone suspended sediment movement is a low-frequency phenomenon, with the relatively high-frequency component (normal wave period) contributing little to the amount of total sediment transported. Development of a computational technique based upon discrete Fourier analysis and digital filtering called Spectrally Filtered Integration (SFI) provides the calculation and filtering of true units of sediment change in grams-per-liter. Moreover, the SFI technique eliminates the possibility spurious sediment information created by the presence of air bubbles in the water column. Generally, higher-frequency sediment movement is more common during storm conditions than during normal non-storm conditions. This movement is controlled not by the prevailing wave and swell periods, but by a longer period which may be due to water interactions below the surface.

scholarly journals Effect of Acute Mental Stress on Heart Rate and QT Variability in Postmyocardial Infarction Patients

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Damiano Magrì ◽  
Gianfranco Piccirillo ◽  
Raffaele Quaglione ◽  
Annalaura Dell’Armi ◽  
Marilena Mitra ◽  
...  
Keyword(s):  
Acute Stress ◽  
Management Strategies ◽  
Low Frequency ◽  
Frequency Component ◽  
Postmyocardial Infarction ◽  
Increased Risk ◽  
Qt Variability Index ◽  
Qt Variability ◽  
Variability Index

Emotionally charged events are associated with an increased risk of sudden cardiac death (SCD). In this study we assessed RR and QT variability index (QTVI) at baseline during anger recall test (AR). We calculated QTVI from a 5-min ECG recording and from a 10-beats segment around the presumed maximum sympathetic activation in thirty post-myocardial infarction patients under β-blocker therapy and 10 controls underwent. In all groups, the low-frequency component of RR and SBP increased during AR. In all recordings, the QTVI calculated on a 5-min ECG recording and the were higher in patients than in controls (P < 0.05). The QTVI during AR remained unchanged from baseline within each group. Conversely, during AR, the in controls diminished significantly (P < 0.05) from baseline whereas in patients remained unchanged. The inability to buffer an acute stress-induced increase in sympathetic activity could explain why events charged with acute stress are associated with an increased risk of ventricular arrhythmias in this setting of patients and support the role of cognitive behavior stress management strategies.

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