Hidden Periodicities Analysis and its Application in Geophysics

2004 ◽  
pp. 187-194
Author(s):  
Zhongjie Xie
Keyword(s):  
Hidden Periodicities

Component statistical analysis of second order hidden periodicities

2014 ◽  
Vol 26 ◽  
pp. 50-70 ◽  
Author(s):  
I. Javorskyj ◽  
D. Dehay ◽  
I. Kravets
Keyword(s):  
Statistical Analysis ◽  
Second Order ◽  
Hidden Periodicities

Design Wind Speeds Using Fast Fourier Transform

2011 ◽  
pp. 1576-1591
Author(s):  
Z.. Ismail ◽  
N. H. Ramli ◽  
Z.. Ibrahim ◽  
T. A. Majid ◽  
G. Sundaraj ◽  
...  
Keyword(s):  
Time Series ◽  
Fourier Transform ◽  
Spectral Density ◽  
Fast Fourier Transform ◽  
Time Series Data ◽  
Absolute Magnitude ◽  
Stationary Pattern ◽  
Wind Speeds ◽  
Hidden Periodicities ◽  
Using Data

In this chapter, a study on the effects of transforming wind speed data, from a time series domain into a frequency domain via Fast Fourier Transform (FFT), is presented. The wind data is first transformed into a stationary pattern from a non-stationary pattern of time series data using statistical software. This set of time series is then transformed using FFT for the main purpose of the chapter. The analysis is done through MATLAB software, which provides a very useful function in FFT algorithm. Parameters of engineering significance such as hidden periodicities, frequency components, absolute magnitude and phase of the transformed data, power spectral density and cross spectral density can be obtained. Results obtained using data from case studies involving thirty-one weather stations in Malaysia show great potential for application in verifying the current criteria used for design practices.

scholarly journals On testing for the presence of hidden periodicities in time series

2015 ◽  
Vol 10 (1) ◽  
pp. 729-737
Author(s):  
Khadidja Bensouici ◽  
Zaher Mohdeb
Keyword(s):  
Time Series ◽  
Hidden Periodicities

The search for hidden periodicities in biological time series revisited

1989 ◽  
Vol 139 (4) ◽  
pp. 487-515 ◽  
Author(s):  
Harold B. Dowse ◽  
John M. Ringo
Keyword(s):  
Time Series ◽  
Biological Time ◽  
Hidden Periodicities

scholarly journals On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

2008 ◽  
Vol 26 (9) ◽  
pp. 2899-2910 ◽  
Author(s):  
V. V. Lobzin ◽  
V. V. Krasnoselskikh ◽  
K. Musatenko ◽  
T. Dudok de Wit
Keyword(s):  
Electric Field ◽  
Shock Front ◽  
Energetic Electron ◽  
Bow Shock ◽  
Langmuir Waves ◽  
Shock Surface ◽  
High Frequency Electric Field ◽  
Earth’S Bow Shock ◽  
Hidden Periodicities ◽  
Field Fluctuations

Abstract. A new method for remote sensing of the quasiperpendicular part of the bow shock surface is presented. The method is based on analysis of high frequency electric field fluctuations corresponding to Langmuir, upshifted, and downshifted oscillations in the electron foreshock. Langmuir waves usually have maximum intensity at the upstream boundary of this region. All these waves are generated by energetic electrons accelerated by quasiperpendicular zone of the shock front. Nonstationary behavior of the shock, in particular due to rippling, should result in modulation of energetic electron fluxes, thereby giving rise to variations of Langmuir waves intensity. For upshifted and downshifted oscillations, the variations of both intensity and central frequency can be observed. For the present study, WHISPER measurements of electric field spectra obtained aboard Cluster spacecraft are used to choose 48 crossings of the electron foreshock boundary with dominating Langmuir waves and to perform for the first time a statistical analysis of nonstationary behavior of quasiperpendicular zone of the Earth's bow shock. Analysis of hidden periodicities in plasma wave energy reveals shock front nonstationarity in the frequency range 0.33 fBi<f<fBi, where fBi is the proton gyrofrequency upstream of the shock, and shows that the probability to observe such a nonstationarity increases with Mach number. The profiles observed aboard different spacecraft and the dominating frequencies of the periodicities are usually different. Hence nonstationarity and/or rippling seem to be rather irregular both in space and time rather than resembling a quasiregular wave propagating on the shock surface.

Determination of Periodic Variations in Sub-Daily GPS Positions of Volcanic Areas

GEOMATICA ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 107-117
Author(s):  
G. Akay ◽  
P. Dare ◽  
R.B. Langley
Keyword(s):  
Ground Deformation ◽  
Gps Data ◽  
Short Term ◽  
Volcanic Processes ◽  
Hidden Periodicities ◽  
Gps Data Processing ◽  
Tidal Constituents ◽  
Low Activity ◽  
Deformation Measurements

Deformation caused by a volcano (e.g., from volcanic activity) can be a good indicator of volcanic processes; ground deformation measurements using geodetic tools can be useful to monitor this movement. This study concentrates on detecting short-term movements occurring during both low activity periods and the eruptive stages of a volcano on the island of Montserrat by using sub-daily (epoch-by-epoch) GPS data processing approaches. The GPS data are obtained from UNAVCO for stations surrounding the Soufrière Hills Volcano during the May 20, 2006, volcanic eruption period and during the Fall 2012 period (a period of lower activity). In order to analyze hidden periodicities within the data, Least Squares Spectral Analysis has been used. Our results show that the sub-daily peaks are located at near diurnal and semidiurnal tidal constituents (K1 and K2) with up to 5 mm amplitude.

scholarly journals ON THE IDENTIFICATION OF SYSTEMS AND THE UNSCRAMBLING OF DATA, I. HIDDEN PERIODICITIES

1965 ◽  
Vol 53 (5) ◽  
pp. 907-910 ◽  
Author(s):  
R. E. Bellman ◽  
H. H. Kagiwada ◽  
R. E. Kalaba
Keyword(s):  
Hidden Periodicities
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