The detection and characterization of high frequency and high wavenumber solar oscillations

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National Aeronautics and Space Administration, National Technical Information Service, distributor , [Washington, DC, Springfield, Va
Solar oscillat
Statementby David Neil Fernandes.
Series[NASA contractor report] -- NASA CR-191622., NASA contractor report -- NASA CR-191622.
ContributionsUnited States. National Aeronautics and Space Administration.
The Physical Object
Pagination1 v.
ID Numbers
Open LibraryOL14688946M


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Get this from a library. The detection and characterization of high frequency and high wavenumber solar oscillations. [David Neil Fernandes; United States. National Aeronautics and. -the detection and characterization of high frequency and high wavenumber i solar oscillations] isubmitted a dissertation to the department of physics and the committee on graduate studies of stanford university in partial fulfillment of the requirements for the degree of doctor of philosophy a i by david neil femandus i jume Doppler shift measurements of the Na D(sub 1) absorption line have revealed solar oscillations in a new regime of frequency and wavenumber.

Oscillations of vertical velocities in the temperature minimum and low chromosphere of the Sun are observed with frequencies ranging up to mHz. There is no evidence for chromospheric modes of 3 minute : David Neil Fernandes. The detection and characterization of high frequency and high wavenumber solar : David Neil.

Description The detection and characterization of high frequency and high wavenumber solar oscillations FB2

Fernandes. A novel method called the damped-oscillator oscillator detector (DOOD) has been developed that is capable of very high resolution time-frequency analysis.

DOOD can be adapted for the reliable, automated detection of high frequency oscillations (HFOs) in the by: 1. frequencies of high-degree f-modes are signi—cantly diƒerent from those given by the simple dispersion relation u2\gk. The f-mode peaks in power spectra are distinctly asymmetric, and use of an asym-metric pro—le increases the —tted frequency, bringing it closer to the frequencies computed for a solar Cited by: 1.

Introduction. Precise identification of the epileptogenic tissue can improve the success rate of epilepsy surgery. High frequency oscillations (HFOs) are promising electrographic biomarkers that identify the epileptogenic cortex more accurately than the currently used interictal spikes (Bragin et al.,Worrell et al.,Jirsch et al.,Urrestarazu et al.,Schindler et al Cited by: interictal high-frequency oscillations (HFOs) > 80 Hz.

HFOs are defined as spontaneous EEG events in the fre-quency range between 80 and Hz, consisting of at least four oscillations that clearly stand out from the background activity.1 HFOs are subdivided into ripples ranging from 80 to Hz and fast ripples > Hz.2 For more details onCited by: High-Resolution Frequency-Wavenumber Spectrum Analysis Abstract-The output of an array bfoensors is considered to be a homogeneous random field.

In this case there is a spectral representa- tion for this field, similar to that for stationary random processes, which consists of a superposition of traveling waves. The frequency-File Size: KB. The detection and characterization of high frequency and high wavenumber solar oscillations book Fernandes, P.

Sherrer, T. Tarbell, and A. Title. Observations of high-frequency and high-wavenumber solar oscillations. Very high spatial resolution two-dimensional solar spectroscopy with video CCDs. Astronomy & Astrophysics, –, and M.

Vazquez. Centre-to-limb variation of solar granulation along the. High‐frequency oscillations (HFOs) are a promising biomarker for the epileptogenic zone. It has not been possible, however, to differentiate physiological from pathological HFOs, and baseline rates of HFO occurrence vary substantially across brain by: High-frequency oscillations in a solar active region coronal loop Article in Monthly Notices of the Royal Astronomical Society (2) September with 18 Reads How we measure 'reads'.

About this book Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume This volume provides a comprehensive overview of externally generated ULF waves and transients in the Earth's space environment, including practically all the latest advances as of.

Abstract. High Frequency Oscillations (HFOs, >80 Hz) are events that have been linked to the seizure onset zone (SOZ). Few studies have identified HFOs in noninvasive EEG and MEG signals due to the high signal-to-noise ratio (SNR) required, but Cited by: 2.

Continuing previous work on total solar eclipse data, we provide further obervational evidence for the existence of high-frequency MHD waves in coronal loops. Wavelet analysis is used to identify 21 areas of 4×4 arcsec 2 with periodic intensity oscillations.

The frequency range of these detections was Hz and all last for at least 3. A spectrum of weakly guided waves in the solar atmosphere at frequencies as high as mHz (10 s period) has been detected with high-cadence solar image sequences from the Transition Region and.

Oscillation Detection Algorithm Development Summary Report & Test Plan is the interim report for the Oscillation Detection and Analysis (contract number:work authorization number: TRP) conducted by Pacific Northwest National Laboratory.

The information from this project contributes to PIER’s Energy Systems Integration Program. solar-like oscillations, is hard to explain by chance alone (and hence a candidate detection).

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We apply the method to solar photometry data, whose quality was systematically de- graded to test the performance of the MWPS at low signal-to-noise ratios.

of solar coronal oscillations. Terradas – High frequency oscillations in active regions and sunspots. Muglach – Application of the POD in the study of the solar atmospheric dynamics.

Vecchio – Closing Summary Review. A large number of acoustic frequencies have already been detected, leading to a "seismic" model of the Sun rather close to the actual standard solar models. The core however is not yet well constrained by these observations and frequencies of low degree, low frequency modes which penetrate deeply into the solar core are needed.

We present here a study on the sensitivity of low Cited by: 1. We introduce a new method to detect solar-like oscillations in frequency power spectra of stellar observations, under conditions of very low signal-to-noise ratio.

The Moving-Windowed-Power-Search (MWPS) searches the power spectrum for signatures of excess power, over and above slowly varying (in frequency) background contributions from stellar granulation and shot or instrumental by: 2.

Abstract: Low-frequency inter-area oscillation is a potentially dangerous phenomenon in power systems involving exchange of power among generators in different areas. In this paper, we study the characteristics of inter-area oscillation by analyzing the distribution of the oscillation energy.

First, we introduce equations for the kinetic energy of generators and the potential energy of network Cited by: High-Frequency Oscillations. The first demonstration that gap junctions are involved in the generation of high-frequency oscillations in the hippocampus has been provided by Ylinen et al.

They showed that the anesthetic drug halothane, which also blocks gap junctions, prevented the occurrence of high-frequency oscillations in the CA1. Proc. SPIEOptics in Atmospheric Propagation and Adaptive Systems XX, (12 January ); doi: / High frequency oscillations (HFOs) are a biomarker of epileptogenicity.

Visual marking of HFOs is highly time-consuming and inevitably subjective, making automatic detection necessary.

We compare four existing detectors on the same and baselines Cited by: High-frequency oscillations (HFOs) are EEG field potentials with frequencies higher than 30 Hz; commonly the frequency band between 30 – 70 Hz is denominated the gamma band, but with the discovery of activities at frequencies higher than 70 Hz a variety of terms have been proposed to describe the latter (Gotman and Crone ).In general we may consider that the term HFO encompasses Cited by: Detection of unstable low frequency oscillations based on PMU measurements Abstract: A new algorithm based on wide area measurements and Discrete Wavelet Transform (DFT) to detect the unstable low frequency power swing oscillations of synchronous generators in a power system is.

Abstract We present m-averaged solar p- and f-mode oscillation frequencies over the frequency range nu greater than and less than mHz and the spherical harmonic degree range l greater than or equal to and less than or equal to from full-disk, x pixel, Ca II intensity images collected June with a temporal cadence of 60 s.

the LFO signal is decomposed into a high-resonance component, a low-resonance component and a residual by RSSD. The LFO signal is the output of an underdamped system with high quality factor and high-resonance property at a specific frequency.

The high-resonance component is the denoised LFO signal, and the residual contains most of the by:. Prograde and retrograde sectoral oscillations of the Sun have been observed so as to determine frequency differences produced by rotation.

Oscillations in the frequency Cited by:   High-frequency oscillations (HFOs) have been proposed as a novel marker for epileptogenic tissue, spurring tremendous research interest into the characterization of these transient events.

A wealth of continuously recorded intracranial electroencephalographic (iEEG) data is currently available from patients undergoing invasive monitoring for.quasi-periodic oscillations (QPOs) at and Hz (i.e., with a frequency ratio), several types of low-frequency QPOs, and strong variations on a timescale of a few hundred seconds.

The discovery of high-frequency QPOs in H supports predictions that these QPOs should be more easily observed in high inclination systems.