ON THE FREQUENCY CONTENT OF SINGLE PULSES AND PERIODIC WAVES

Quantitative image analysis systems have been used for several years in research and quality control applications in various fields including metallurgy and medicine. The technique has been applied as an extension of subjective microscopy to problems requiring quantitative results and which are amenable to automatic methods of interpretation.Feature extraction. In the most general sense, a feature can be defined as a portion of the image which differs in some consistent way from the background. A feature may be characterized by the density difference between itself and the background, by an edge gradient, or by the spatial frequency content (texture) within its boundaries. The task of feature extraction includes recognition of features and encoding of the associated information for quantitative analysis.Quantitative Analysis. Quantitative analysis is the determination of one or more physical measurements of each feature. These measurements may be straightforward ones such as area, length, or perimeter, or more complex stereological measurements such as convex perimeter or Feret's diameter.

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Self-Reported Frequency, Content, and Functions of Inner Speech

PsycEXTRA Dataset ◽

10.1037/e520602012-202 ◽

2011 ◽

Author(s):

Alain Morin ◽

Bob Uttl ◽

Breanne Hamper

Keyword(s):

Inner Speech ◽

Frequency Content

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Runup Recipe for Periodic Waves on Uniformly Sloping Beaches

Coastal Engineering 1966 ◽

10.1061/9780872620087.022 ◽

1967 ◽

Author(s):

Wm. G. Van Dorn

Keyword(s):

Periodic Waves

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

European Heart Journal ◽

10.1093/ehjci/ehaa946.3447 ◽

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

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Multirate Processing with Selective Subbands and Machine Learning for Efficient Arrhythmia Classification

Sensors ◽

10.3390/s21041511 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1511

Author(s):

Saeed Mian Qaisar ◽

Alaeddine Mihoub ◽

Moez Krichen ◽

Humaira Nisar

Keyword(s):

Machine Learning ◽

Signal Reconstruction ◽

Computational Cost ◽

Machine Learning Techniques ◽

Features Selection ◽

Frequency Content ◽

Fixed Rate ◽

Ecg Signals ◽

Learning Techniques ◽

Multirate Processing

The usage of wearable gadgets is growing in the cloud-based health monitoring systems. The signal compression, computational and power efficiencies play an imperative part in this scenario. In this context, we propose an efficient method for the diagnosis of cardiovascular diseases based on electrocardiogram (ECG) signals. The method combines multirate processing, wavelet decomposition and frequency content-based subband coefficient selection and machine learning techniques. Multirate processing and features selection is used to reduce the amount of information processed thus reducing the computational complexity of the proposed system relative to the equivalent fixed-rate solutions. Frequency content-dependent subband coefficient selection enhances the compression gain and reduces the transmission activity and computational cost of the post cloud-based classification. We have used MIT-BIH dataset for our experiments. To avoid overfitting and biasness, the performance of considered classifiers is studied by using five-fold cross validation (5CV) and a novel proposed partial blind protocol. The designed method achieves more than 12-fold computational gain while assuring an appropriate signal reconstruction. The compression gain is 13 times compared to fixed-rate counterparts and the highest classification accuracies are 97.06% and 92.08% for the 5CV and partial blind cases, respectively. Results suggest the feasibility of detecting cardiac arrhythmias using the proposed approach.

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Periodic waves travelling along an unsmooth boundary via the fractal variational theory

Results in Physics ◽

10.1016/j.rinp.2021.104549 ◽

2021 ◽

pp. 104549

Author(s):

Bo-Rong Zou ◽

Kang-Jia Wang

Keyword(s):

Periodic Waves ◽

Variational Theory

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Tunnel performance during the Puebla-Mexico 19 September 2017 earthquake

Earthquake Spectra ◽

10.1177/8755293020976140 ◽

2020 ◽

Vol 36 (2_suppl) ◽

pp. 288-313

Author(s):

Juan M Mayoral ◽

Gilberto Mosqueda ◽

Daniel De La Rosa ◽

Mauricio Alcaraz

Keyword(s):

Mexico City ◽

Seismic Performance ◽

Urban Areas ◽

Numerical Study ◽

Three Dimensional ◽

Frequency Content ◽

Seismic Performance Evaluation ◽

Ground Deformations ◽

Under Construction ◽

Observed Damage

Seismic performance of tunnels during earthquakes in densely populated areas requires assessing complex interactions with existing infrastructure such as bridges, urban overpasses, and metro stations, including low- to medium-rise buildings. This article presents the numerical study of an instrumented tunnel, currently under construction on stiff soils, located in the western part of Mexico City, during the Puebla-Mexico 19 September 2017 earthquake. Three-dimensional finite difference models were developed using the software FLAC3D. Initially, the static response of the tunnel was evaluated accounting for the excavation technique. Then, the seismic performance evaluation of the tunnel was carried out, computing ground deformations and factors of safety, considering soil nonlinearities. Good agreement was observed between predicted and observed damage during post-event site observations. Once the soundness of the numerical model was established, a numerical study was undertaken to investigate the effect of frequency content in tunnel-induced ground motion incoherence for tunnels built in cemented stiff soils. A series of strong ground motions recorded during normal and subduction events were used in the simulations, considering a return period of 250 years, as recommended in the Mexico City building code. From the results, it was concluded that the tunnel presence leads to important frequency content modification in the tunnel surroundings which can affect low- to mid-rise stiff structures located nearby. This important finding must be taken into account when assessing the seismic risk in highly populated urban areas, such as Mexico City.

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