High Frequency Intensity Fluctuations
نویسندگان
چکیده
Intensity fluctuations were measured during August 2002 near San Diego using 20 and 40 kHz cw and fm signals. Source-receiver separation was 1km; source depths were 10m to 67m; receiver hydrophone depths were 44m to 217m. A 15-element chain of CTD sensors was towed to measure horizontal temperature and salinity with 1m resolution. Comparing the spectra of the acoustic intensity fluctuations and sound speed fluctuations indicate that much of the energy in the oceanic processes occurs at time scales not captured in the acoustic records. (Work supported by ONR Code 321US under the ARL Program)
منابع مشابه
Origin of synchronized low-frequency blood oxygen level-dependent fluctuations in the primary visual cortex.
BACKGROUND AND PURPOSE Low-frequency (<0.08 Hz) fluctuations in spontaneous blood oxygen level-dependent (BOLD) signal intensity show synchronization across anatomically interconnected and functionally specific brain regions, suggesting a neural origin of fluctuations. To determine the mechanism by which high-frequency neural activity results in low-frequency BOLD fluctuations, I obtained measu...
متن کاملMeasurement of Pulsewidth via Correlations in Intensity Fluctuations
We conisder a novel method to measure the width, ∆t, of a pulse of relativistic electrons (a beam pulse), via the correlations in the intensity fluctuations of radiation emitted when the pulse passes through a magnetic field. Since intensity fluctuations appear to be a kind of noise, this technique is somewhat counterinituitive. The measurement is based on synchrotron radiation, whose spectrum ...
متن کاملSubhertz spectral fluctuations from high-density excitons in coupled quantum wells.
In 1994 Butov et al. [Phys. Rev. Lett. 73, 304 (1994)] reported large, extremely low-frequency fluctuations in the luminescence intensity from indirect excitons in a coupled quantum well. We have reproduced these fluctuations in a similar structure. Our observations indicate, however, that the fluctuations are spectral fluctuations rather than intensity fluctuations. We have eliminated several ...
متن کاملSimultaneously suppressing frequency and intensity noise in a Nd:YAG nonplanar ring oscillator by means of the current-lock technique.
We show that frequency and intensity noise in a Nd:YAG laser are correlated to a high degree and can be traced to the same underlying cause, namely, power fluctuations of the pump source. Because of this correlation, simultaneous suppression of frequency and intensity noise by 30 dB is achieved by means of a single actuator, the pump power.
متن کاملExperimental investigation on sound of a centrifugal blower and fluctuating pressure on its volute
The Research has shown that the primary sound source in centrifugal turbomachines is the blade passing frequency noise, which is caused by due to impac rotor exit flow with the volute and the wild pressure fluctuations. In this paper, a centrifugal blower with forward facing blades has been selected and the sound created by it in the output channel has been investigated in different operating c...
متن کامل