Effect of spectral time-lag correlation coefficient and signal averaging on airborne CO 2 DIAL measurements

1997 ◽  
Author(s):  
Avishai Ben-David ◽  
Richard G. Vanderbeek ◽  
Steven W. Gotoff ◽  
Francis M. D'Amico
Keyword(s):  
Correlation Coefficient ◽  
Time Lag ◽  
Signal Averaging ◽  
Time Lag Correlation

scholarly journals The photon-index–time-lag correlation in black hole X-ray binaries

2017 ◽  
Vol 473 (4) ◽  
pp. 4644-4652 ◽  
Author(s):  
Pablo Reig ◽  
Nikolaos D. Kylafis ◽  
Iossif E. Papadakis ◽  
María Teresa Costado
Keyword(s):  
Black Hole ◽  
Time Lag ◽  
X Ray ◽  
Photon Index ◽  
X Ray Binaries ◽  
Time Lag Correlation

scholarly journals Increase in public interest concerning alternative medicine during the COVID-19 pandemic in Indonesia: a Google Trends study

F1000Research ◽  
2021 ◽  
Vol 9 ◽  
pp. 1201
Author(s):  
Dewi Rokhmah ◽  
Khaidar Ali ◽  
Serius Miliyani Dwi Putri ◽  
Khoiron Khoiron
Keyword(s):  
Alternative Medicine ◽  
Public Interest ◽  
Time Lag ◽  
Google Trends ◽  
Rank Test ◽  
Search Term ◽  
Alternative Medicines ◽  
Search Volume ◽  
Relative Search Volume ◽  
Time Lag Correlation

Background: The COVID-19 pandemic has triggered individuals to increase their healthy behaviour in order to prevent transmission, including improving their immunity potentially through the use of alternative medicines. This study aimed to examine public interest on alternative medicine during the COVID-19 pandemic using Google Trends in Indonesia. Methods: Employing a quantitative study, the Spearman rank test was used to analyze the correlation between Google Relative Search Volume (RSV) of various search terms, within the categories of alternative medicine, herbal medicine and practical activity, with COVID-19 cases. In addition, time lag correlation was also investigated. Results: Public interest toward alternative medicine during COVID-19 pandemic in Indonesia is dramatically escalating. All search term categories (alternative medicine, medical herbal, and alternative medicine activities) were positively associated with COVID-19 cases (p<0.05). The terms ‘ginger’ (r=0.6376), ‘curcumin’ (r=0.6550) and ‘planting ginger’ (0.6713) had the strongest correlation. Furthermore, time lag correlation between COVID-19 and Google RSV was also positively significant (p<0.05). Conclusion: Public interest concerning alternative medicine related terms dramatically increased after the first COVID-19 confirmed case was reported in Indonesia. Time lag correlation showed good performance using weekly data. The Indonesian Government will play an important role to provide and monitor information related to alternative medicine in order for the population to receive the maximum benefit.

scholarly journals Jitter Extraction in a Noisy Signal by Fast Fourier Transform and Time Lag Correlation

2018 ◽  
Vol 884 ◽  
pp. 113-121 ◽  
Author(s):  
Gehan Anthonys ◽  
Michael J. Cree ◽  
Lee Streeter
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Time Lag ◽  
Reference Signal ◽  
Clock Signal ◽  
Eye Diagram ◽  
Noisy Signals ◽  
Random Jitter ◽  
Reference Clock ◽  
Time Lag Correlation

Jitter in an electronic signal is any deviation in, or displacement of, the signal in time. This paper investigates on decomposition of two types of jitter, namely, periodic and random jitter in noisy signals. Generally, an oscilloscope generates an eye diagram by overlaying sweeps of different segments of a long data stream driven by the reference clock signal. We use the fast Fourier transform with time lag correlation of the signal since we do not have a clock reference signal and apply this technique to simulated noisy signals. We separately injected a random jitter (of known amount), periodic jitter (with known frequency and amount), and both together to various modulation frequencies of sinusoidal signals. The approach is validated by several experiments with numerous values in jitter parameters. When we separately inject random jitter (5 ps) and periodic jitter (5 ps at 4.37 MHz) to the signal, we obtained the results (4.52±0.25 ps) and (4.93±0.04 ps at 4.40±0.04 MHz), respectively.

scholarly journals Interrelationships between MODIS/Terra remotely sensed snow cover and the hydrometeorology of the Quesnel River Basin, British Columbia, Canada

2009 ◽  
Vol 13 (8) ◽  
pp. 1439-1452 ◽  
Author(s):  
J. Tong ◽  
S. J. Déry ◽  
P. L. Jackson
Keyword(s):  
British Columbia ◽  
Snow Cover ◽  
Correlation Coefficient ◽  
River Basin ◽  
Time Lag ◽  
Spatial Filter ◽  
In Situ Observation ◽  
Cloud Coverage ◽  
Snow Cover Extent

Abstract. A spatial filter (SF) method is adopted to reduce the cloud coverage from the Moderate Resolution Imaging Spectroradiometer (MODIS) 8-day snow products (MOD10A2) between 2000–2007 in the Quesnel River Basin (QRB) of British Columbia, Canada. A threshold of k = 2 cm of snow depth measurements at four in-situ observation stations in the QRB are used to evaluate the accuracy of MODIS snow products MOD10A1, MOD10A2, and SF. Using the MOD10A2 and the SF, the relationships between snow ablation, snow cover extent (SCE), snow cover fraction (SCF), streamflow and climate variability are assessed. Based on our results we are able to draw several interesting conclusions. Firstly, the SF method reduces the average cloud coverage in the QRB from 15% for MOD10A2 to 9%. Secondly, the SF increases the overall accuracy (OA) based on the threshold k = 2 cm by about 2% compared to MOD10A2 and by about 10% compared to MOD10A1 at higher elevations. The OA for the four in-situ stations decreases with elevation with 93.1%, 87.9%, 84.0%, and 76.5% at 777 m, 1265 m, 1460 m, and 1670 m, respectively. Thirdly, an aggregated 1°C rise in average air temperature during spring leads to a 10-day advance in reaching 50% SCF (SCF50%) in the QRB. The correlation coefficient between normalized SCE of the SF and normalized streamflow is −0.84 (p<0.001) for snow ablation seasons. There is a 32-day time lag for snow ablation to impact the streamflow the strongest at the basin outlet. The linear correlation coefficient between SCF50% and 50% normalized accumulated runoff (R50%) attains 0.82 (p<0.01). This clearly demonstrates the strong links that exist between the SCF depletion and the hydrology of this sub-boreal, mountainous watershed.

Detrended Correlogram Method for Non-Stationary Time-Series Analysis

2021 ◽  
pp. 2250012
Author(s):  
G. F. Zebende ◽  
E. F. Guedes
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Correlation Coefficient ◽  
Memory Effect ◽  
Cross Correlation ◽  
Time Lag ◽  
Stationary Time Series ◽  
Time Lags ◽  
Statistical Tool ◽  
Auto Correlation

A correlogram is a statistical tool that is used to check time-series memory by computing the auto-correlation coefficient as a function of the time lag. If the time-series has no memory, then the auto-correlation must be close to zero for any time lag, otherwise if there is a memory, then the auto-correlations must be significantly different from zero. Therefore, based on the robust detrended cross-correlation coefficient, [Formula: see text], we propose the detrended correlogram method in this paper, which will be tested for some time-series (simulated and empirical). This new statistical tool is able to visualize a complete map of the auto-correlation for many time lags and time-scales, and can therefore analyze the memory effect for any time-series.

scholarly journals STOCK RETURN AND TRADING VOLUME IN LQ45 INDEX

2017 ◽  
Vol 10 (02) ◽  
Author(s):  
Clara Constantine ◽  
Kim Sung Suk
Keyword(s):  
Trading Volume ◽  
Stock Return ◽  
Time Lag ◽  
Time Lag Correlation

<p>Penelitian ini berfokus hubungan antara return dan volume perdagangan dengan data harian perusahaan di<br />LQ45. Model GARCH Bivariat digunakan untuk mengamati hubungan antara return dan volume<br />perdagangan. Untuk mengetahui hubungan lebih lanjut antar variabel tersebut, digunakan pendekatan<br />time lag correlation. Untuk verifikasi hubungan tersebut, datanya dibagi menjadi dua kelompok<br />berdasarkan ukuran volume perdagangan dan ukuran perusahaan. Hasilnya menunjukkan bahwa<br />kelompok volume perdagangan hanya menyebabkan Granger kausal ke volume perdangangan, tetapi<br />sebaliknya tidak. Sementara pada kelompok ukuran perusahaan, masing-masing menunjukkan hasil yang<br />berbeda. Pada ukuran perusahaan kecil dan menengah, return dan volume mempunyai dua arah (bilateral)<br />Granger kausal. Namun, tidak ditemukan hubungan kausal bagi ukuran perusahaan besar. Semua<br />kelompok ukuran volume dan kelompok ukuran perusahaan menunjukkan korelasi lag waktu positif,<br />sehingga terdapat efek anti-leverage.<br />Kata kunci: return, volume perdagangan, Bivariat GARCH</p>

scholarly journals Interrelationships between MODIS/Terra remotely sensed snow cover and the hydrometeorology of the Quesnel River Basin, British Columbia, Canada

2009 ◽  
Vol 6 (3) ◽  
pp. 3687-3723 ◽  
Author(s):  
J. Tong ◽  
S. J. Déry ◽  
P. L. Jackson
Keyword(s):  
British Columbia ◽  
Snow Cover ◽  
Correlation Coefficient ◽  
River Basin ◽  
Time Lag ◽  
Spatial Filter ◽  
In Situ Observation ◽  
Cloud Coverage ◽  
Snow Cover Extent

Abstract. A spatial filter (SF) method is adopted to reduce the cloud coverage from the Moderate Resolution Imaging Spectroradiometer (MODIS) 8-day snow products (MOD10A2) between 2000–2007 in the Quesnel River Basin (QRB) of British Columbia, Canada. A threshold of k=2 cm of snow depth measurements at four in-situ observation stations in the QRB are used to evaluate the accuracy of MODIS snow products MOD10A1, MOD10A2, and SF. Based on the MOD10A2 and the SF, the relationships between snow ablation, snow cover extent (SCE), snow cover fraction (SCF), streamflow and climate variability are assessed. Based on our results we are able to draw several interesting conclusions. Firstly, the SF method reduces the average cloud coverage in the QRB from 15% for MOD10A2 to 9%. Secondly, the SF increases the overall accuracy (OA) based on the threshold k=2 cm by about 2% compared to MOD10A2 and by about 10% compared to MOD10A1 at higher elevations. The OA for the four in-situ stations decreases with elevation with 93.1%, 87.9%, 84.0%, and 76.5% at 777 m, 1265 m, 1460 m, and 1670 m, respectively. Thirdly, an aggregated 1°C rise in average air temperature during spring leads to a 10-day advance in reaching 50% SCF (SCF50%) in the QRB. The correlation coefficient between normalized SCE of the SF and normalized streamflow is −0.84 (p<0.001) for snow ablation seasons. There is a 32-day time lag for snow ablation to impact the streamflow the strongest at the basin outlet. The linear correlation coefficient between SCF50% and 50% normalized accumulated runoff (R50%) attains 0.82 (p<0.01). This clearly demonstrates the strong links that exist between the SCF depletion and the hydrology of this sub-boreal, mountainous watershed.

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