Long-range hydroacoustic observations of the Monowai Volcanic Centre as a proxy for seasonal variations in sound propagation

2020 ◽  
Author(s):  
Pieter Smets ◽  
Kees Weemstra ◽  
Läslo Evers
Keyword(s):  
Volcanic Activity ◽  
Seasonal Variations ◽  
Cross Correlation ◽  
Sound Propagation ◽  
Signal To Noise Ratio ◽  
Seismic Station ◽  
Volcanic Centre ◽  
Processing Scheme ◽  
Cook Island ◽  
Cross Correlation Analysis

<p>Hydroacoustic activity of the submarine Monowai Volcanic Centre (MVC) is repeatedly observed at two distant triplet hydrophone stations, south of Juan Fernandez Islands (H03S, 9,159km) and north of Ascension Island (H10N, 15,823km). <em>T</em>-phase converted energy recorded at the broadband seismic station Rarotonga on Cook Island (RAR, 1,845km) is used as a reference for the cross-correlation analysis. A detailed processing scheme for the calculation of the daily cross-correlation functions (CCF) of the hydroacoustic and seismic data is provided. Preprocessing is essential to account for the non-identical measurements and sensitivities as well as the different sample rates.<span> </span>Further postprocessing by systematic data selection has to be applied before stacking CCFs in order to account for the non-continuous activity of the MVC source.<span> </span>Daily volcanic activity is determined for the period from 2006 until 2018 using the signal-to-noise ratio of the CCFs assuming sound propagation in the SOFAR channel. Monthly stacked CCFs with clear volcanic activity are used to study seasonal variations in sound propagation between the MVC and the hydrophone stations.<span> </span>In winter, however, a faster than expected signal is observed at H10N which is hypothesized to (partial) propagation through the formed sea ice along the path near Antarctica.</p>

scholarly journals Signal Processing for Parametric Acoustic Sources Applied to Underwater Communication

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5878
Author(s):  
María Campo-Valera ◽  
Ivan Felis-Enguix ◽  
Isidro Villó-Pérez
Keyword(s):  
Cross Correlation ◽  
Sound Propagation ◽  
Signal To Noise Ratio ◽  
Processing Technique ◽  
Underwater Communication ◽  
Carrier Wave ◽  
Acoustic Communications ◽  
Correlation Processing ◽  
Novel Processing ◽  
Special Relevance

For years, in the field of underwater acoustics, a line of research with special relevance for applications of environmental monitoring and maritime security has been developed that explores the possibilities of non-linear phenomena of sound propagation, especially referring to the so-called parametric effect or self-modulation. This article shows the results of using a new modulation technique based on sine-sweep signals, compared to classical modulations (FSK and PSK). For each of these modulations, a series of 16-bit strings of information with different frequencies and durations have been performed, with the same 200 kHz carrier wave. All of them have been tested in the Hydroacoustic Laboratory of the CTN and, through the application of cross-correlation processing, the limitations and improvements of this novel processing technique have been evaluated. This allows reaching better limits in discrimination of bits and signal-to-noise ratio used in underwater parametric acoustic communications.

scholarly journals Theoretical characterisation of strand cross-correlation in ChIP-seq

2020 ◽  
Author(s):  
Hayato Anzawa ◽  
Hitoshi Yamagata ◽  
Kengo Kinoshita
Keyword(s):  
Chromatin Immunoprecipitation ◽  
Cross Correlation ◽  
Simulation Analysis ◽  
Signal To Noise Ratio ◽  
Correlation Coefficients ◽  
Peak Calling ◽  
The Public ◽  
Cross Correlation Analysis ◽  
Maximum Coefficient ◽  
High Consistency

Abstract Background: Strand cross-correlation profiles are used for both peak calling pre-analysis and quality control (QC) in chromatin immunoprecipitation followed by sequencing (ChIP-seq) analysis. Despite its potential for robust and accurate assessments of signal-to-noise ratio (S/N) because of its peak calling independence, it remains unclear what aspects of quality such strand cross-correlation profiles actually measure. Results: We introduced a simple model to simulate the mapped read-density of ChIP-seq and then derived the theoretical maximum and minimum of cross-correlation coefficients between strands. The results suggest that the maximum coefficient of typical ChIP-seq samples is directly proportional to the number of total mapped reads and the square of the ratio of signal reads, and inversely proportional to the number of peaks and the length of read-enriched regions. Simulation analysis supported our results and evaluation using 790 ChIP-seq data obtained from the public database demonstrated high consistency between calculated cross-correlation coefficients and estimated coefficients based on the theoretical relations and peak calling results. In addition, we found that the mappability-bias-correction improved sensitivity, enabling differentiation of maximum coefficients from the noise level. Based on these insights, we proposed virtual S/N (VSN), a novel peak call-free metric for S/N assessment. We also developed PyMaSC, a tool to calculate strand cross-correlation and VSN efficiently. VSN achieved most consistent S/N estimation for various ChIP targets and sequencing read depths. Furthermore, we demonstrated that a combination of VSN and pre-existing peak calling results enable the estimation of the numbers of detectable peaks for posterior experiments and assess peak calling results. Conclusions: We present the first theoretical insights into the strand cross-correlation, and the results reveal the potential and the limitations of strand cross-correlation analysis. Our quality assessment framework using VSN provides peak call-independent QC and will help in the evaluation of peak call analysis in ChIP-seq experiments.

scholarly journals Theoretical characterisation of strand cross-correlation in ChIP-seq

2019 ◽  
Author(s):  
Hayato Anzawa ◽  
Hitoshi Yamagata ◽  
Kengo Kinoshita
Keyword(s):  
Chromatin Immunoprecipitation ◽  
Cross Correlation ◽  
Simulation Analysis ◽  
Signal To Noise Ratio ◽  
Correlation Coefficients ◽  
Peak Calling ◽  
The Public ◽  
Cross Correlation Analysis ◽  
Maximum Coefficient ◽  
High Consistency

Abstract Background: Strand cross-correlation profiles are used for both peak calling pre-analysis and quality control in chromatin immunoprecipitation followed by sequencing (ChIP-seq) analysis. Despite its potential for robust and accurate assessments of signal-to-noise ratio (S/N) of ChIP-seq samples, it remains unclear what aspects of quality such strand cross-correlation profiles actually measure. Results: We introduced a simple model to simulate the mapped read-density of ChIP-seq and then derived the theoretical maximum and minimum of cross-correlation coefficients between strands. The results suggest that the maximum coefficient of typical ChIP-seq samples is directly proportional to the number of total mapped reads and the square of the ratio of signal reads, and inversely proportional to the number of peaks and the length of read-enriched regions. We also developed PyMaSC to efficiently generate strand cross-correlation profiles. Simulation analysis supported our results and evaluation using 790 ChIP-seq data obtained from the public database demonstrated high consistency between calculated cross-correlation coefficients and estimated coefficients based on the theoretical relations and peak calling results. In addition, we found that the mappability-bias-correction improved sensitivity, enabling differentiation of maximum coefficients from the noise level. Conclusions: We present the first theoretical insights into the strand cross-correlation and the results reveal the potential and the limitations of strand cross-correlation analysis. Our work will help in the establishment of better QC metrics using strand cross-correlation.

scholarly journals Theoretical characterisation of strand cross-correlation in ChIP-seq

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Hayato Anzawa ◽  
Hitoshi Yamagata ◽  
Kengo Kinoshita
Keyword(s):  
Chromatin Immunoprecipitation ◽  
Cross Correlation ◽  
Simulation Analysis ◽  
Signal To Noise Ratio ◽  
Correlation Coefficients ◽  
Peak Calling ◽  
The Public ◽  
Cross Correlation Analysis ◽  
Maximum Coefficient ◽  
High Consistency

Abstract Background Strand cross-correlation profiles are used for both peak calling pre-analysis and quality control (QC) in chromatin immunoprecipitation followed by sequencing (ChIP-seq) analysis. Despite its potential for robust and accurate assessments of signal-to-noise ratio (S/N) because of its peak calling independence, it remains unclear what aspects of quality such strand cross-correlation profiles actually measure. Results We introduced a simple model to simulate the mapped read-density of ChIP-seq and then derived the theoretical maximum and minimum of cross-correlation coefficients between strands. The results suggest that the maximum coefficient of typical ChIP-seq samples is directly proportional to the number of total mapped reads and the square of the ratio of signal reads, and inversely proportional to the number of peaks and the length of read-enriched regions. Simulation analysis supported our results and evaluation using 790 ChIP-seq data obtained from the public database demonstrated high consistency between calculated cross-correlation coefficients and estimated coefficients based on the theoretical relations and peak calling results. In addition, we found that the mappability-bias-correction improved sensitivity, enabling differentiation of maximum coefficients from the noise level. Based on these insights, we proposed virtual S/N (VSN), a novel peak call-free metric for S/N assessment. We also developed PyMaSC, a tool to calculate strand cross-correlation and VSN efficiently. VSN achieved most consistent S/N estimation for various ChIP targets and sequencing read depths. Furthermore, we demonstrated that a combination of VSN and pre-existing peak calling results enable the estimation of the numbers of detectable peaks for posterior experiments and assess peak calling results. Conclusions We present the first theoretical insights into the strand cross-correlation, and the results reveal the potential and the limitations of strand cross-correlation analysis. Our quality assessment framework using VSN provides peak call-independent QC and will help in the evaluation of peak call analysis in ChIP-seq experiments.

scholarly journals Comparison of Terrestrial and Lunar Time Scales by Giant Pulsar Impulses

2021 ◽  
Vol 65 (11) ◽  
pp. 1136-1144
Author(s):  
A. E. Rodin ◽  
V. V. Oreshko ◽  
V. A. Fedorova
Keyword(s):  
Time Scales ◽  
Cross Correlation ◽  
Arrival Time ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
The Moon ◽  
Recording Equipment ◽  
Giant Pulses ◽  
Cross Correlation Analysis ◽  
Pulse Arrival

Abstract We have developed a model for the time delay of pulse arrival between stations on the Moon and Earth. Comparison of the lunar and terrestrial time scales is proposed to be carried out by comparing the arrival time moments of giant pulses from pulsars. A method for such a comparison has been developed based on the cross-correlation analysis of the received pulses. Using the example of giant pulses from the pulsar PSR 0531+21, we showed that the error of comparing scales in the case of a high signal-to-noise ratio reaches a sub-discrete level and, thus, is determined by the reception band of the recording equipment.

scholarly journals Theoretical characterisation of strand cross-correlation in ChIP-seq

2020 ◽  
Author(s):  
Hayato Anzawa ◽  
Hitoshi Yamagata ◽  
Kengo Kinoshita
Keyword(s):  
Chromatin Immunoprecipitation ◽  
Cross Correlation ◽  
Simulation Analysis ◽  
Signal To Noise Ratio ◽  
Correlation Coefficients ◽  
Peak Calling ◽  
The Public ◽  
Cross Correlation Analysis ◽  
Maximum Coefficient ◽  
High Consistency

Abstract Background: Strand cross-correlation profiles are used for both peak calling pre-analysis and quality control (QC) in chromatin immunoprecipitation followed by sequencing (ChIP-seq) analysis. Despite its potential for robust and accurate assessments of signal-to-noise ratio (S/N) because of its peak calling independence, it remains unclear what aspects of quality such strand cross-correlation profiles actually measure. Results: We introduced a simple model to simulate the mapped read-density of ChIP-seq and then derived the theoretical maximum and minimum of cross-correlation coefficients between strands. The results suggest that the maximum coefficient of typical ChIP-seq samples is directly proportional to the number of total mapped reads and the square of the ratio of signal reads, and inversely proportional to the number of peaks and the length of read-enriched regions. Simulation analysis supported our results and evaluation using 790 ChIP-seq data obtained from the public database demonstrated high consistency between calculated cross-correlation coefficients and estimated coefficients based on the theoretical relations and peak calling results. In addition, we found that the mappability-bias-correction improved sensitivity, enabling differentiation of maximum coefficients from the noise level. Based on these insights, we proposed virtual S/N (VSN), a novel peak call-free metric for S/N assessment. We also developed PyMaSC, a tool to calculate strand cross-correlation and VSN efficiently. VSN achieved most consistent S/N estimation for various ChIP targets and sequencing read depths. Furthermore, we demonstrated that a combination of VSN and pre-existing peak calling results enable the estimation of the numbers of detectable peaks for posterior experiments and assess peak calling results. Conclusions: We present the first theoretical insights into the strand cross-correlation, and the results reveal the potential and the limitations of strand cross-correlation analysis. Our quality assessment framework using VSN provides peak call-independent QC and will help in the evaluation of peak call analysis in ChIP-seq experiments.

A Study of Clustering for the Enhancement of Image Resolution in Dynamic Photon Emission

2019 ◽  
Author(s):  
S. Chef ◽  
C. T. Chua ◽  
C. L. Gan
Keyword(s):  
Signal To Noise Ratio ◽  
Photon Emission ◽  
Optical Signal ◽  
Image Resolution ◽  
Time Dimension ◽  
Processing Scheme ◽  
3D Space ◽  
Initial Acquisition ◽  
Resolution Limits ◽  
Emission Microscopy

Abstract Limited spatial resolution and low signal to noise ratio are some of the main challenges in optical signal observation, especially for photon emission microscopy. As dynamic emission signals are generated in a 3D space, the use of the time dimension in addition to space enables a better localization of switching events. It can actually be used to infer information with a precision above the resolution limits of the acquired signals. Taking advantage of this property, we report on a post-acquisition processing scheme to generate emission images with a better image resolution than the initial acquisition.

Application of Cross-correlation Analysis Method for Measurement of the Fluid Flow Rate Based on X-ray Radiation

2019 ◽  
Vol 11 (1) ◽  
pp. 01025-1-01025-5 ◽  
Author(s):  
N. A. Borodulya ◽  
◽  
R. O. Rezaev ◽  
S. G. Chistyakov ◽  
E. I. Smirnova ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Correlation Analysis ◽  
Flow Rate ◽  
Cross Correlation ◽  
Fluid Flow Rate ◽  
Analysis Method ◽  
X Ray ◽  
Cross Correlation Analysis ◽  
Correlation Analysis Method
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