Estimation of Free Core Resonance Parameters Based on Long-Term Strain Observations in the Diurnal Frequency Band

2019 ◽  
Vol 55 (3) ◽  
pp. 389-396 ◽  
Author(s):  
V. K. Milyukov ◽  
A. Amoruso ◽  
L. Crescentini ◽  
A. P. Mironov ◽  
A. V. Myasnikov ◽  
...  
Keyword(s):  
Frequency Band ◽  
Resonance Parameters ◽  
Free Core Resonance

scholarly journals Estimation of free core resonance parameters based on long-term strain observations in the diurnal frequency band

2019 ◽  
pp. 41-50
Author(s):  
V. K. Milyukov ◽  
A. Amoruso ◽  
L. Crescentini ◽  
A. P. Mironov ◽  
A. V. Myasnikov ◽  
...  
Keyword(s):  
Laser Interferometer ◽  
Liquid Core ◽  
Resonant Mode ◽  
Parameter Estimates ◽  
Retrograde Motion ◽  
Tidal Waves ◽  
Superconducting Gravimeters ◽  
Fixed Reference ◽  
Free Core Resonance

The free core nutation (FCN) is one of the Earth’s rotational eigenmodes, which is caused by the retrograde motion of the liquid core relative to the mantle. The FCN period and Q-factor are determined by the elastic properties of the core/mantle boundary (CMB) and their electromagnetic interaction. In the celestial coordinate system, the FCN period is about 430 days; in the Earth-fixed reference frame this effect manifests itself in the form of the free core resonance (FCR) whose frequency falls in the diurnal tidal band. FCR observation requires highly accurate measurement of the amplitudes and phases of the near-diurnal tidal waves. In particular, the parameter estimates for minor waves K1, P1, Ψ1, and Φ1 are critically important for evaluating the FCR effect, i.e., the period and decay of this resonant mode. The progress in the experimental study of FCR is mainly due to the accumulation of the data from superconducting gravimeters and VLBI; at the same time, also the data of the precision laser strainmeters were used. In this work, the FCR effect is studied based on the long-term strain precision records by two European stations: Baksan, Russia (laser interferometer–strainmeter with a measuring armlength of 75 m [Milyukov et al., 2005; 2007] and Gran Sasso, Italy (two perpendicular laser interferometer–strainmeters, BA and BC, each with a measuring armlength of 90 m [Amoruso and Crescentini, 2009]).

Voice Activity Detector (VAD) Based on Long-Term Mel Frequency Band Features

2016 ◽  
pp. 352-358
Author(s):  
Sergey Salishev ◽  
Andrey Barabanov ◽  
Daniil Kocharov ◽  
Pavel Skrelin ◽  
Mikhail Moiseev
Keyword(s):  
Frequency Band ◽  
Voice Activity Detector ◽  
Voice Activity

Induction of long-term oscillations in the γ frequency band by nAChR activation in rat hippocampal CA3 area

Neuroscience ◽  
2015 ◽  
Vol 301 ◽  
pp. 49-60 ◽  
Author(s):  
X. Zhang ◽  
X.Y. Ge ◽  
J.G. Wang ◽  
Y.L. Wang ◽  
Y. Wang ◽  
...  
Keyword(s):  
Frequency Band ◽  
Hippocampal Ca3

scholarly journals Sparsely Wiring Connectivity in the Upper Beta Band Characterizes the Brains of Top Swimming Athletes

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinzhen Pei ◽  
Xiaoying Qi ◽  
Yuzhou Jiang ◽  
Xunzhang Shen ◽  
An-Li Wang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Frequency Band ◽  
Brain Connectivity ◽  
Phase Lag ◽  
Complex Reaction ◽  
Beta Band ◽  
Neural Connections ◽  
The Difference ◽  
The Brain

Human brains are extremely energy costly in neural connections and activities. However, it is unknown what is the difference in the brain connectivity between top athletes with long-term professional trainings and age-matched controls. Here we ask whether long-term training can lower brain-wiring cost while have better performance. Since elite swimming requires athletes to move their arms and legs at different tempos in time with high coordination skills, we selected an eye-hand-foot complex reaction (CR) task to examine the relations between the task performance and the brain connections and activities, as well as to explore the energy cost-efficiency of top athletes. Twenty-one master-level professional swimmers and 23 age-matched non-professional swimmers as controls were recruited to perform the CR task with concurrent 8-channel EEG recordings. Reaction time and accuracy of the CR task were recorded. Topological network analysis of various frequency bands was performed using the phase lag index (PLI) technique to avoid volume conduction effects. The wiring number of connections and mean frequency were calculated to reflect the wiring and activity cost, respectively. Results showed that professional athletes demonstrated better eye-hand-foot coordination than controls when performing the CR task, indexing by faster reaction time and higher accuracy. Comparing to controls, athletes' brain demonstrated significantly less connections and weaker correlations in upper beta frequency band between the frontal and parietal regions, while demonstrated stronger connectivity in the low theta frequency band between sites of F3 and Cz/C4. Additionally, athletes showed highly stable and low eye-blinking rates across different reaction performance, while controls had high blinking frequency with high variance. Elite athletes' brain may be characterized with energy efficient sparsely wiring connections in support of superior motor performance and better cognitive performance in the eye-hand-foot complex reaction task.

Ultra-compact self-diplexing antenna based on quarter-mode substrate integrated waveguide with high isolation

2021 ◽  
pp. 1-6
Author(s):  
Ayman A. Althuwayb
Keyword(s):  
Frequency Band ◽  
Long Term Evolution ◽  
Substrate Integrated Waveguide ◽  
Cross Polarization ◽  
Cavity Resonators ◽  
Frequency Bands ◽  
High Isolation ◽  
Term Evolution ◽  
Better Than

Abstract This article presents the design of an ultra-compact cavity-backed self-diplexing antenna with high isolation employing quarter-mode substrate integrated waveguide (QMSIW). The proposed antenna is constructed by using QMSIW, slot, and two 50Ω feed lines. Two eighth-mode cavity resonators are designed by inserting a slot on the top side of the rectangular substrate integrated waveguide to operate at 2.6 and 4.9 GHz for long-term evolution and public safety band applications, respectively. The proposed design allows to tune any frequency band independently by keeping other bands unaltered. The size of antenna is ultra-compact, due to the use of QMSIW cavity. The isolation between two ports is >35 dB. The antenna achieves 5.34 and 5.68 dBi peak gains at 2.6 and 4.9 GHz, respectively. The efficiency of the antenna is >85% at both frequency bands. The antenna provides more than 20.9 dB front-to-back-ratio and better than 21 dB separation between co-to-cross polarization levels. The designed antenna is validated through fabrication and measurement.

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