scholarly journals Effects of supershear rupture speed on the high-frequency content ofSwaves investigated using spontaneous dynamic rupture models and isochrone theory

2008 ◽  
Vol 113 (B5) ◽  
Author(s):  
A. Bizzarri ◽  
P. Spudich
Keyword(s):  
High Frequency ◽  
Frequency Content ◽  
Dynamic Rupture ◽  
Rupture Speed ◽  
High Frequency Content

Comparison of wavelet continuous transform and signal averaged ECG for high frequency content and late potential detection in healthy individuals

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
D Garcia Iglesias ◽  
J.M Rubin Lopez ◽  
D Perez Diez ◽  
C Moris De La Tassa ◽  
F.J De Cos Juez ◽  
...  
Keyword(s):  
High Frequency ◽  
Classical Method ◽  
Total Power ◽  
Frequency Content ◽  
Healthy Individuals ◽  
Time Frequency ◽  
Qt Intervals ◽  
Long Time ◽  
Power Content ◽  
High Frequency Content

Abstract Introduction The Signal Averaged ECG (SAECG) is a classical method forSudden Cardiac Death (SCD) risk assessment, by means of Late Potentials (LP) in the filtered QRS (fQRS)[1]. But it is highly dependent on noise and require long time records, which make it tedious to use. Wavelet Continuous Transform (WCT) meanwhile is easier to use, and may let us to measure the High Frequency Content (HFC) of the QRS and QT intervals, which also correlates with the risk of SCD [2,3]. Whether the HFC of the QRS and QT measured with the WCT is a possible subrogate of LP, has never been demonstrated. Objective To demonstrate if there is any relationship between the HFC measured with the WCT and the LP analyzed with the SAECG. Methods Data from 50 consecutive healthy individuals. The standard ECG was digitally collected for 3 consecutive minutes. For the WCT Analysis 8 consecutive QT complexes were used and for the SAECG Analysis all available QRS were used. The time-frequency data of each QT complex were collected using the WCT as previously described [3] and the Total, QRS and QT power were obtained from each patient. For the SAECG, bipolar X, Y and Z leads were used with a bidirectional filter at 40 to 250 Hz [1]. LP were defined as less than 0.05 z in the terminal part of the filtered QRS and the duration (SAECG LP duration) and root mean square (SAECG LP Content) of this LP were calculated. Pearson's test was used to correlate the Power content with WCT analysis and the LP in the SAECG. Results There is a strong correlation between Total Power and the SAECG LP content (r=0.621, p<0.001). Both ST Power (r=0.567, p<0.001) and QRS Power (r=0.404, p=0.004) are related with the SAECG LP content. No correlation were found between the Power content (Total, QRS or ST Power) and the SAECG LP duration. Also no correlation was found between de SAECG LP content and duration. Conclusions Total, QRS and ST Power measured with the WCT are good surrogates of SAECG LP content. No correlation were found between WCT analysis and the SAECG LP duration. Also no correlation was found between the SAECG LP content and duration. This can be of high interest, since WCT is an easier technique, not needing long recordings and being less affected by noise. Funding Acknowledgement Type of funding source: None

HIGH-FREQUENCY CONTENT OF SPECIAL RECORDINGS

1965 ◽  
Author(s):  
John H. Healy ◽  
Wayne H. Jackson
Keyword(s):  
High Frequency ◽  
Frequency Content ◽  
High Frequency Content

Broadband seismic over/under sources and their designature-deghosting

Geophysics ◽  
2017 ◽  
Vol 82 (5) ◽  
pp. P61-P73 ◽  
Author(s):  
Lasse Amundsen ◽  
Ørjan Pedersen ◽  
Are Osen ◽  
Johan O. A. Robertsson ◽  
Martin Landrø
Keyword(s):  
Seismic Data ◽  
High Frequency ◽  
Low Frequency ◽  
Point Sources ◽  
High Frequency Side ◽  
Frequency Content ◽  
Source Depth ◽  
Deep Sources ◽  
The Cost ◽  
High Frequency Content

The source depth influences the frequency band of seismic data. Due to the source ghost effect, it is advantageous to deploy sources deep to enhance the low-frequency content of seismic data. But, for a given source volume, the bubble period decreases with the source depth, thereby degrading the low-frequency content. At the same time, deep sources reduce the seismic bandwidth. Deploying sources at shallower depths has the opposite effects. A shallow source provides improved high-frequency content at the cost of degraded low-frequency content due to the ghosting effect, whereas the bubble period increases with a lesser source depth, thereby slightly improving the low-frequency content. A solution to the challenge of extending the bandwidth on the low- and high-frequency side is to deploy over/under sources, in which sources are towed at two depths. We have developed a mathematical ghost model for over/under point sources fired in sequential and simultaneous modes, and we have found an inverse model, which on common receiver gathers can jointly perform designature and deghosting of the over/under source measurements. We relate the model for simultaneous mode shooting to recent work on general multidepth level array sources, with previous known solutions. Two numerical examples related to over/under sequential shooting develop the main principles and the viability of the method.

scholarly journals HIGH FREQUENCY CONTENT OF THE SURFACE ECG CORRELATES WITH THE PRESENCE OF SYMPATHETIC NERVES IN THE VENTRICLES OF THE HEART

2017 ◽  
Vol 69 (11) ◽  
pp. 422
Author(s):  
Larisa G. Tereshchenko ◽  
Golriz Sedaghat ◽  
Ryan Gardner ◽  
Muammar Kabir ◽  
Beth Habecker
Keyword(s):  
High Frequency ◽  
Sympathetic Nerves ◽  
Frequency Content ◽  
Surface Ecg ◽  
High Frequency Content

scholarly journals Standing shock prevents propagation of sparks in supersonic explosive flows

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Jens von der Linden ◽  
Clare Kimblin ◽  
Ian McKenna ◽  
Skyler Bagley ◽  
Hsiao-Chi Li ◽  
...  
Keyword(s):  
Radio Frequency ◽  
High Frequency ◽  
Fluid Dynamic ◽  
Supersonic Jet ◽  
Explosive Eruptions ◽  
Jet Flows ◽  
Frequency Content ◽  
Frequency Regime ◽  
High Frequency Content ◽  
Volcanic Jet

AbstractVolcanic jet flows in explosive eruptions emit radio frequency signatures, indicative of their fluid dynamic and electrostatic conditions. The emissions originate from sparks supported by an electric field built up by the ejected charged volcanic particles. When shock-defined, low-pressure regions confine the sparks, the signatures may be limited to high-frequency content corresponding to the early components of the avalanche-streamer-leader hierarchy. Here, we image sparks and a standing shock together in a transient supersonic jet of micro-diamonds entrained in argon. Fluid dynamic and kinetic simulations of the experiment demonstrate that the observed sparks originate upstream of the standing shock. The sparks are initiated in the rarefaction region, and cut off at the shock, which would limit their radio frequency emissions to a tell-tale high-frequency regime. We show that sparks transmit an impression of the explosive flow, and open the way for novel instrumentation to diagnose currently inaccessible explosive phenomena.

The Effects of Discretization Errors on the High Frequency Content of In-Structure Response Spectra

2016 ◽  
Author(s):  
Greg Mertz ◽  
Robert Spears ◽  
Thomas Houston
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Time History ◽  
Response Spectra ◽  
Frequency Content ◽  
Time Step ◽  
Structure Response ◽  
Time History Response ◽  
Ground Motion Records ◽  
High Frequency Content

The next generation ground motion prediction equations predict significant high frequency seismic input for rock sites in the Central Eastern United States (CEUS). This high frequency motion is transmitted to basemat supported components and may be transmitted to components supported on elevated slabs. The existing ASCE 4 analysis requirements were initially developed based on seismic motions having lower frequencies, typical of ground motions in the Western United States (WUS). The adequacy of the existing ASCE 4 analysis requirements are examined using high frequency CEUS spectral shapes and the potential error inherent in using the existing approach to computing in structure response spectra is quantified. Modifications to reduce potential error in the existing ASCE 4 criteria are proposed. In structure response spectra are typically generated for a subsystem given the time history response of a building region. The building time history response is based on analyses that use either modal time history superposition, direct integration or complex frequency response analysis of the building and supporting soil. Input to the building analyses consist of either real or synthetic discretized ground motion records. The discretized ground motion records are often based on recorded ground motion seeds and are often limited to a 0.005 second time step. Thus the time step of the seed record often limits the frequency content of the problem. Both the building analyses and in structure response spectra subsystem analysis may interpolate the discretized ground motion records to obtain stable results. This interpolation generates errors that are propagated through the analyses used to calculate in structure response spectra. These errors may result in extraneous high frequency content in the in structure response spectra. Errors are quantified by comparison of time history parameters, Fourier components and in structure response spectra.

A Marine Seismic Source with Enhanced Low and Reduced High Frequency Content

2019 ◽  
Author(s):  
G. Baeten ◽  
D. Chavan ◽  
B. Kuvshinov ◽  
F. Ten Kroode ◽  
S. Ronen ◽  
...  
Keyword(s):  
High Frequency ◽  
Seismic Source ◽  
Frequency Content ◽  
Marine Seismic ◽  
High Frequency Content
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