Periodic Oscillation Analysis of Gps Height Time Series Based on HHT

2015 ◽  
pp. 533-544
Author(s):  
Xiaolei Wang ◽  
Qin Zhang ◽  
Lidu Zhao ◽  
Shuangcheng Zhang
Keyword(s):  
Time Series ◽  
Periodic Oscillation ◽  
Oscillation Analysis

scholarly journals Analysing nystagmus waveforms: a computational framework

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Richard V. Abadi ◽  
Ozgur E. Akman ◽  
Gemma E. Arblaster ◽  
Richard A. Clement
Keyword(s):  
Time Series ◽  
Periodic Orbit ◽  
Late Onset ◽  
Periodic Oscillation ◽  
Permutation Entropy ◽  
Entropy Measure ◽  
Unstable Periodic Orbit ◽  
Additional Tool ◽  
Orbit Analysis ◽  
Over Time

AbstractWe present a new computational approach to analyse nystagmus waveforms. Our framework is designed to fully characterise the state of the nystagmus, aid clinical diagnosis and to quantify the dynamical changes in the oscillations over time. Both linear and nonlinear analyses of time series were used to determine the regularity and complexity of a specific homogenous phenotype of nystagmus. Two-dimensional binocular eye movement recordings were carried out on 5 adult subjects who exhibited a unilateral, uniplanar, vertical nystagmus secondary to a monocular late-onset severe visual loss in the oscillating eye (the Heimann-Bielschowsky Phenomenon). The non-affected eye held a central gaze in both horizontal and vertical planes (± 10 min. of arc). All affected eyes exhibited vertical oscillations, with mean amplitudes and frequencies ranging from 2.0°–4.0° to 0.25–1.5 Hz, respectively. Unstable periodic orbit analysis revealed only 1 subject exhibited a periodic oscillation. The remaining subjects were found to display quasiperiodic (n = 1) and nonperiodic (n = 3) oscillations. Phase space reconstruction allowed attractor identification and the computation of a time series complexity measure—the permutation entropy. The entropy measure was found to be able to distinguish between a periodic oscillation associated with a limit cycle attractor, a quasiperiodic oscillation associated with a torus attractor and nonperiodic oscillations associated with higher-dimensional attractors. Importantly, the permutation entropy was able to rank the oscillations, thereby providing an objective index of nystagmus complexity (range 0.15–0.21) that could not be obtained via unstable periodic orbit analysis or attractor identification alone. These results suggest that our framework provides a comprehensive methodology for characterising nystagmus, aiding differential diagnosis and also permitting investigation of the waveforms over time, thereby facilitating the quantification of future therapeutic managements. In addition, permutation entropy could provide an additional tool for future oculomotor modelling.

scholarly journals Development of the homogenized monthly precipitation series during 1910–2014 and its changes in Hunan Province, China

2017 ◽  
Vol 8 (4) ◽  
pp. 791-801 ◽  
Author(s):  
Jiadong Peng ◽  
Yufang Liao ◽  
Yuanhua Jiang ◽  
Jianming Zhang ◽  
Xingren Qi
Keyword(s):  
Time Series ◽  
Abrupt Change ◽  
Linear Trend ◽  
Periodic Oscillation ◽  
Hunan Province ◽  
Monthly Precipitation ◽  
Precipitation Series ◽  
Precipitation Time Series ◽  
Significant Linear Trend ◽  
Complete Precipitation

Abstract Based on the statistical method and the historical evolution of meteorological stations, the precipitation time series for each station in Hunan Province of China during 1910–2014 are tested for their homogeneity and then adjusted. The missing data caused by war and other reasons at the eight meteorological stations which had records before 1950 is filled by interpolation using adjacent observations, and complete precipitation time series since the establishment of stations are constructed. After that, according to the representative analysis of each station in different time periods, the precipitation series of Hunan Province during 1910–2014 are built and changes are analyzed. The results indicate that the annual precipitation has no significant linear trend but has obvious inter-decadal fluctuation during 1910–2014 and a periodic oscillation of 20 years is the most significant. Precipitation in winter (DJF) and summer (JJA) shows a slight wetter trend, and a slight dryer trend in spring (MAM) and autumn (SON). Abrupt change test suggests that annual and seasonal precipitations except for MAM and SON have abrupt ascending changes in the recent 100 years.

scholarly journals Variations in the key hydrological elements of the Yarlung Zangbo River basin

2018 ◽  
Vol 19 (4) ◽  
pp. 1088-1096 ◽  
Author(s):  
Dian Li ◽  
Jia Li ◽  
Linglei Zhang ◽  
Yun Deng ◽  
Yaowen Zhang
Keyword(s):  
Time Series ◽  
River Basin ◽  
Periodic Oscillation ◽  
Monthly Variation ◽  
Middle Section ◽  
Periodic Oscillations ◽  
Yarlung Zangbo River ◽  
Wavelet Variance ◽  
High Level ◽  
Different Time Scales

Abstract Based on the monthly water level, runoff, precipitation and evaporation data from the four main hydrometric stations in the middle section of the Yarlung Zangbo River basin from 1956 to 2000, the periodic oscillations, trends and transformation characteristics at different time-scales are investigated via wavelet analysis. Moreover, the main periods of each time-series are identified by estimating the wavelet variance. The results show that the transformation scales of the monthly variation of the key hydrological elements over the last 44 years were 80–120, 40–70 and 16–24 months and that a high level of consistency was maintained at 16–24 months, where the periodic oscillation was the most significant. In addition, the first and second main periods of all hydrological elements were 18 and 9 months, respectively.

Poyang Lake Region Precipitation Singular Spectrum Analysis

2014 ◽  
Vol 955-959 ◽  
pp. 3006-3010 ◽  
Author(s):  
Jian Ying Wang ◽  
Pan Pan Zhang ◽  
Shu Sen Pang
Keyword(s):  
Time Series ◽  
Spectrum Analysis ◽  
Poyang Lake ◽  
Singular Spectrum Analysis ◽  
Periodic Oscillation ◽  
Jiangxi Province ◽  
Rainfall Time Series ◽  
Lake Area ◽  
Singular Spectrum ◽  
Poyang Lake Area

Poyang Lake is located in the northern part of Jiangxi Province, is one of the important Yangtze River flood storage lakes. Use Mann-Kendall test the trends and mutation of the Poyang Lake area rainfall time series, and use singular spectrum analysis (SSA) method to analyze the time series of periodic oscillation characteristics. The results showed that, the Poyang Lake area rainfall time series no significant upward or downward trend, there are quasi 4-5 years, 8-11 years, 20-year periodicity.

scholarly journals Periodic Oscillation Analysis for a Coupled FHN Network Model with Delays

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Yuanhua Lin
Keyword(s):  
Network Model ◽  
Periodic Oscillation ◽  
Neural System ◽  
Oscillation Analysis

The existence of periodic oscillation for a coupled FHN neural system with delays is investigated. Some criteria to determine the oscillations are given. Simple and practical criteria for selecting the parameters in this network are provided. Some examples are also presented to illustrate the result.

Period Multiplication in a Continuous Time Series of Radio-Frequency DBDs at Atmospheric Pressure

2012 ◽  
Vol 11 (4) ◽  
pp. 1226-1235 ◽  
Author(s):  
Jiao Zhang ◽  
Yanhui Wang ◽  
Dezhen Wang
Keyword(s):  
Time Series ◽  
Radio Frequency ◽  
Atmospheric Pressure ◽  
Model Simulation ◽  
Fluid Model ◽  
Dissipative System ◽  
Period Doubling ◽  
Periodic Oscillation ◽  
Strong Nonlinearity ◽  
Nonlinear Behaviors

AbstractAs a spatially extended dissipative system with strong nonlinearity the radio-frequency (rf) dielectric-barrier discharges (DBDs) at atmospheric pressure possess complex spatiotemporal nonlinear behaviors. In this paper, the time-domain nonlinear behaviors of rf DBD in atmospheric argon are studied numerically by a one-dimensional fluid model. Simulation results show that, under appropriate controlling parameters, the rf DBD can undergo a transition from single-period state to chaos through period doubling bifurcation with increasing discharge time, i.e., the regular periodic oscillation and chaos can coexist in a long time series of the atmospheric-pressure rf DBD. With increasing applied voltage amplitude, the duration of the periodic oscillation reduces gradually and chaotic zone increases, and finally the whole discharge series becomes completely chaotic state. This is different from conventional period doubling route to chaos. Moreover, the spatial characteristics of rf period-doubling discharge and chaos, as well as the parameter range of various discharge behaviors occurring are also investigated in this paper.

scholarly journals Complex variability of Kepler AGN revealed by recurrence analysis

2020 ◽  
Vol 497 (3) ◽  
pp. 3418-3439 ◽  
Author(s):  
R A Phillipson ◽  
P T Boyd ◽  
A P Smale ◽  
M S Vogeley
Keyword(s):  
Time Series ◽  
Light Curve ◽  
Time Scales ◽  
Power Spectra ◽  
Periodic Oscillation ◽  
Light Curves ◽  
Recurrence Analysis ◽  
Spectra Analysis ◽  
Modes Of Variability ◽  
Underlying Processes

ABSTRACT The advent of new time domain surveys and the imminent increase in astronomical data expose the shortcomings of traditional time series analysis (such as power spectra analysis) in characterizing the abundantly varied, complex, and stochastic light curves of Active Galactic Nuclei (AGNs). Recent applications of novel methods from non-linear dynamics have shown promise in characterizing higher modes of variability and time-scales in AGN. Recurrence analysis in particular can provide complementary information about characteristic time-scales revealed by other methods, as well as probe the nature of the underlying physics in these objects. Recurrence analysis was developed to study dynamical trajectories in phase space, which can be constructed from 1D time series such as light curves. We apply the methods of recurrence analysis to two optical light curves of Kepler-monitored AGN. We confirm the detection and period of an optical quasi-periodic oscillation in one AGN, and confirm multiple other time-scales recovered from other methods ranging from 5 to 60 d in both objects. We detect regions in the light curves that deviate from regularity, provide evidence of determinism and non-linearity in the mechanisms underlying one light curve (KIC 9650712), and determine realizations of a linear stochastic process describe the dominant variability in the other light curve (Zwicky 229–015). We discuss possible underlying processes driving the dynamics of the light curves and their diverse classes of variability.

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