High‐amplitude noise elimination and data restoration

Seismic reflection data obtained across the Quebec Appalachians using the VIBROSEIS (trademark Conoco) technique were recorded with parameters that allowed harmonic distortion arrivals to interfere with layered reflections. The data exhibit reflections from layered miogeoclinal rocks dipping eastward beneath the allochthonous rocks of the orogen; the layering appears to terminate beneath the Notre Dame Anticlinorium. However, as the apparent termination of the layers also occurs at the arrival times of high-amplitude noise harmonics, it may have no geological significance. Precambrian Grenville crust, which probably underlies the layered sediments, extends at least as far east as the apparent termination, and may extend much farther. Examination of the Bouguer gravity field in relation to the seismic reflection data shows that a major gravity change is due to density differences that occur considerably west of the eastern limit of Precambrian Grenville crust. The gravity thus shows no correlation with surface structures proposed as suture zones. An actualistic model incorporates subduction of a passive (Atlantic-type) margin beneath an arc terrain during the Ordovician.

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Influence of High-Amplitude Noise on Boundary-Layer Transition to Turbulence

10.21236/ada359230 ◽

1998 ◽

Cited By ~ 9

Author(s):

William S. Saric

Keyword(s):

Boundary Layer ◽

High Amplitude ◽

Boundary Layer Transition ◽

Transition To Turbulence ◽

Layer Transition ◽

Amplitude Noise

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NOISE EFFECTS ON THE ELECTROSENSE-MEDIATED FEEDING BEHAVIOR OF SMALL PADDLEFISH

Fluctuation and Noise Letters ◽

10.1142/s021947750100024x ◽

2001 ◽

Vol 01 (02) ◽

pp. L71-L86 ◽

Cited By ~ 9

Author(s):

DAVID F. RUSSELL ◽

ANNA TUCKER ◽

BARBARA A. WETTRING ◽

ALEXANDER B. NEIMAN ◽

LON WILKENS ◽

...

Keyword(s):

Feeding Behavior ◽

Stochastic Resonance ◽

Sensory Information ◽

High Amplitude ◽

Body Motion ◽

Electrical Noise ◽

Behavioral Experiments ◽

Noise Effects ◽

Amplitude Noise ◽

Spatial Range

Weak electrical noise applied in the water around small paddlefish, Polyodon spathula, increases the spatial range over which they can detect and capture planktonic prey (Daphnia), demonstrating stochastic resonance at the level of an animal's feeding behavior. Here we show that optimal-amplitude (~ 0.5 μ V · cm -1) noise causes a fish to prefer more vertical angles of attack when striking at prey, as revealed in polar graphs. Increased spatial range is also seen in horizontal directions, as outlying shoulders in the probability distribution of horizontal strike distances. High levels of noise increased the distance that approaching prey travelled along the rostrum (an elongated appendage anterior to the head, functioning as an electrosensitive antenna), before the fish first showed a visible fin or body motion in response. There was no significant effect of optimal-amplitude noise on the rate of strikes, although high-amplitude noise reduced the strike rate. The behavioral data were confirmed in neurophysiological experiments demonstrating that stochastic resonance occurs in individual electroreceptors, and in fact occurs at a similar optimal noise level as in behavioral experiments. We conclude that stochastic resonance can be demonstrated in the behavior of animals, and that animals can make use of the increased sensory information available during near-threshold environmental noise.

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Simulations of noise rejection and mantissa‐only recording: An experiment in high‐amplitude noise reduction with COCORP data

Geophysics ◽

10.1190/1.1441946 ◽

1985 ◽

Vol 50 (4) ◽

pp. 709-714 ◽

Cited By ~ 4

Author(s):

Simon L. Klemperer ◽

Larry Brown

Keyword(s):

Noise Reduction ◽

Dynamic Range ◽

Heavy Traffic ◽

Traffic Noise ◽

High Amplitude ◽

Amplitude Noise ◽

Reflection Data ◽

Noise Rejection ◽

Field Noise ◽

Test Individual

Vertical stacking of Vibroseis® sweeps for the purposes of reflection data enhancement and data compression often smears sporadic noise bursts into summed traces with degrading effects. One noisy record can easily nullify the signal enhancement benefits of stacking the remaining good sweeps (e.g., Gimlin and Smith, 1980). This paper compares different methods of noise editing before vertical stacking, as applied to deep seismic data collected by COCORP (Consortium for Continental Reflection Profiling) in conditions of heavy traffic noise. Noise editing is of particular concern in crustal seismic work where weak reflections from great depths are often critical to interpretations. In our test, individual sweeps rather than the field sum of these sweeps were recorded separately on tape. This procedure, single‐sweep recording, allowed four computer simulations: (A) recording with no noise editing; (B) recording with a field noise‐rejection (NRJ) system; (C) using a more optimal NRJ system which was computed using the characteristics of the recorded sweeps and applied after recording; and (D) recording using mantissa‐only (MO) format. In this initial, limited experiment, we found significantly greater noise reduction with both tailored, postrecording NRJ systems and MO format than with the simple field NRJ currently employed by COCORP. Normally, these alternative recording methods are not used, either because they entail excessive tape handling and preprocessing, as in the case of single‐sweep recording and application of postrecording NRJ, or because they entail loss of dynamic range, as with MO format recording. However, this study suggests that in the presence of severe traffic noise the benefits of these alternative techniques may outweigh their drawbacks.

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Quantification of signal and noise in two-way transmitted wavefields to improve well ties in Cooper Basin, Australia

Interpretation ◽

10.1190/int-2013-0129.1 ◽

2014 ◽

Vol 2 (2) ◽

pp. SD19-SD31 ◽

Cited By ~ 5

Author(s):

Chen Qi ◽

Fred Hilterman

Keyword(s):

High Amplitude ◽

Synthetic Seismogram ◽

Time Varying ◽

Multiple Reflections ◽

Seismic Line ◽

Amplitude Noise ◽

Coal Beds ◽

Low Pass ◽

Internal Multiples ◽

Cooper Basin

Permian coal beds at 2400–2900 m depth in Cooper Basin, Australia have normal-incident reflection coefficient values as large as [Formula: see text]. If internal multiples are included in synthetic seismograms, excellent correlations exist between the synthetic seismogram and seismic, even when more than 50 coal beds are present. However, neither the synthetic seismogram nor the seismic tie the well-log lithologic boundaries because the incident wavefield that strikes a lithologic boundary and returns to the surface contains a signal wavelet followed by high-amplitude noise, which are interbed multiple reflections. Because the spectra of the signal and noise coda at a given two-way time normally do not overlap, time-varying Gaussian filters applied to the near-offset stack enhance the signal and suppress the noise coda. After filtering, the apparent time delay of reflections introduced by the coal beds is removed with variable time shifts (time compression), based on the estimated time-varying signal wavelets. The two-step process of low-pass filtering and compression yields seismic events that successfully tie the lithologic boundaries in the borehole, although with limited resolution. Our preliminary tests on a seismic line indicate that the horizon event associated with the base of a 500-m-thick coal sequence is more coherently imaged with our processing than with conventional processing.

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