In Design of an Ocean Bottom Seismometer Sensor: Minimize Vibration Experienced by Underwater Low-Frequency Noise

Ocean Bottom Seismometers (OBS) placed on the seafloor surface are utilized for measuring the ocean bottom seismic waves. The vibration of OBS excited by underwater noise on its surface may interfere with its measured results of seismic waves. In this particular study, an OBS was placed on the seabed, while ray acoustic theory was used to deduce the sound field distribution around the OBS. Then using this information, the analytical expression for the OBS vibration velocity was obtained in order to find various factors affecting its amplitude. The finite element computing software COMSOL Multiphysics® (COMSOL) was used to obtain the vibration response model of the OBS which was exposed to underwater noise. The vibration velocity for the OBS calculated by COMSOL agreed with the theoretical result. Moreover, the vibration velocity of OBS with different densities, shapes, and characters were investigated as well. An OBS with hemispherical shape, consistent average density as that of the seafloor, and a physical structure of double tank has displayed minimum amplitude of vibration velocity. The proposed COMSOL model predicted the impact of underwater noise while detecting the ocean bottom seismic waves with the OBS. In addition, it provides significant help for the design and optimization of an appropriate OBS.

Download Full-text

Experimental Understanding of the Impact of Channel Percolation on Low Frequency Noise Using Transient Enhanced Diffusion of Channel Dopants

2021 5th IEEE Electron Devices Technology & Manufacturing Conference (EDTM) ◽

10.1109/edtm50988.2021.9421039 ◽

2021 ◽

Author(s):

Shuntaro Fujii ◽

Soichi Morita ◽

Tsutomu Miyazaki

Keyword(s):

Low Frequency ◽

Frequency Noise ◽

Low Frequency Noise ◽

Enhanced Diffusion ◽

Transient Enhanced Diffusion ◽

The Impact

Download Full-text

Comparison of the S/N ratios of low-frequency hydrophones and geophones as a function of ocean depth

Bulletin of the Seismological Society of America ◽

10.1785/bssa0710051649 ◽

1981 ◽

Vol 71 (5) ◽

pp. 1649-1659

Author(s):

Thomas M. Brocher ◽

Brian T. Iwatake ◽

Joseph F. Gettrust ◽

George H. Sutton ◽

L. Neil Frazer

Keyword(s):

Nova Scotia ◽

Continental Margin ◽

Low Frequency ◽

Weather Conditions ◽

Ocean Bottom ◽

Ocean Bottom Seismometer ◽

Scotian Shelf ◽

Ocean Bottom Seismometers ◽

Particle Velocities ◽

Refraction Data

abstract The pressures and particle velocities of sediment-borne signals were recorded over a 9-day period by an array of telemetered ocean-bottom seismometers positioned on the continental margin off Nova Scotia. The telemetered ocean-bottom seismometer packages, which appear to have been very well coupled to the sediments, contained three orthogonal geophones and a hydrophone. The bandwidth of all sensors was 1 to 30 Hz. Analysis of the refraction data shows that the vertical geophones have the best S/N ratio for the sediment-borne signals at all recording depths (67, 140, and 1301 m) and nearly all ranges. The S/N ratio increases with increasing sensor depth for equivalent weather conditions. Stoneley and Love waves detected on the Scotian shelf (67-m depth) are efficient modes for the propagation of noise.

Download Full-text

Ceiling Construction Low-Frequency Noise Issues

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.649.277 ◽

2013 ◽

Vol 649 ◽

pp. 277-280

Author(s):

Petra Berková ◽

Pavel Berka

Keyword(s):

Spectral Analysis ◽

Low Frequency ◽

Sound Insulation ◽

Frequency Noise ◽

Low Frequency Noise ◽

Frequency Tone ◽

The Impact ◽

40 Hz

Through the use of a spectral analysis of the source of noise – person’s movement over the ceiling construction – it was found out that in this kind of noise distinctive low-frequency tone components occur (31,5 - 40 Hz) which is beyond the evaluation area of the impact sound insulation of the ceiling construction, s. [2], [3].

Download Full-text

Making maps of cosmic microwave background polarization for B-mode studies: the POLARBEAR example

Astronomy and Astrophysics ◽

10.1051/0004-6361/201629467 ◽

2017 ◽

Vol 600 ◽

pp. A60 ◽

Cited By ~ 6

Author(s):

Davide Poletti ◽

Giulio Fabbian ◽

Maude Le Jeune ◽

Julien Peloton ◽

Kam Arnold ◽

...

Keyword(s):

Cosmic Microwave Background ◽

Time Domain ◽

Power Spectra ◽

Low Frequency ◽

Frequency Noise ◽

Spectrum Estimation ◽

Microwave Background ◽

Polarization Studies ◽

Ordered Data ◽

The Impact

Analysis of cosmic microwave background (CMB) datasets typically requires some filtering of the raw time-ordered data. For instance, in the context of ground-based observations, filtering is frequently used to minimize the impact of low frequency noise, atmospheric contributions and/or scan synchronous signals on the resulting maps. In this work we have explicitly constructed a general filtering operator, which can unambiguously remove any set of unwanted modes in the data, and then amend the map-making procedure in order to incorporate and correct for it. We show that such an approach is mathematically equivalent to the solution of a problem in which the sky signal and unwanted modes are estimated simultaneously and the latter are marginalized over. We investigated the conditions under which this amended map-making procedure can render an unbiased estimate of the sky signal in realistic circumstances. We then discuss the potential implications of these observations on the choice of map-making and power spectrum estimation approaches in the context of B-mode polarization studies. Specifically, we have studied the effects of time-domain filtering on the noise correlation structure in the map domain, as well as impact it may haveon the performance of the popular pseudo-spectrum estimators. We conclude that although maps produced by the proposed estimators arguably provide the most faithful representation of the sky possible given the data, they may not straightforwardly lead to the best constraints on the power spectra of the underlying sky signal and special care may need to be taken to ensure this is the case. By contrast, simplified map-makers which do not explicitly correct for time-domain filtering, but leave it to subsequent steps in the data analysis, may perform equally well and be easier and faster to implement. We focused on polarization-sensitive measurements targeting the B-mode component of the CMB signal and apply the proposed methods to realistic simulations based on characteristics of an actual CMB polarization experiment, POLARBEAR. Our analysis and conclusions are however more generally applicable.

Download Full-text

Relationships between ocean bottom noise and the environment

Bulletin of the Seismological Society of America ◽

10.1785/bssa0840061991 ◽

1994 ◽

Vol 84 (6) ◽

pp. 1991-2007 ◽

Cited By ~ 2

Author(s):

Jeffrey M. Babcock ◽

Barry A. Kirkendall ◽

John A. Orcutt

Keyword(s):

Gravity Waves ◽

Spectral Characteristics ◽

Low Frequency ◽

Environmental Data ◽

Single Frequency ◽

Frequency Noise ◽

Ocean Bottom ◽

Double Frequency ◽

Frequency Peak ◽

Northern Atlantic

Abstract Observations of ocean bottom low-frequency noise and surface environmental data over a period of 27 days in the northern Atlantic during the SAMSON and SWADE experiments reveal how closely related the noise is to meteorological conditions. Double-frequency microseisms produced by nonlinear interactions of storm-induced surface gravity waves are especially evident in the frequency band 0.16 to 0.3 Hz and show a high variability in both amplitude and peak frequencies. Bifurcated at times, the peak that characterizes the microseism band contains local and distant or “teleseismic” components, which are generated at different locations. Weather and storm fetch appear to be the major contributions to the size and shape of microseism spectra. Storm development on the sea surface is associated with progressively lower microseism frequencies along with a concurrent increase in amplitude. The single-frequency microseism peak is a continuous feature and is observed to portray the same time-dependent spectral characteristics as the portion of the double-frequency peak associated with distant storms. Coherence studies confirm that both peaks (single and teleseismic double) originate at a distant source. These peaks are generated at roughly the same location with some storm component over the coastline.

Download Full-text

Low-frequency behaviour of a sound field inside a reverberant room: Measurements and numerical prediction tools

Building Acoustics ◽

10.1177/1351010x19840974 ◽

2019 ◽

Vol 26 (2) ◽

pp. 93-108

Author(s):

Juan Negreira ◽

Anders Sjöström ◽

Dag Glebe

Keyword(s):

Statistical Methods ◽

Lower Limit ◽

Numerical Models ◽

Low Frequency ◽

Sound Field ◽

Frequency Noise ◽

Low Frequency Noise ◽

Prediction Tools ◽

Acoustic Comfort ◽

Frequency Properties

The low-frequency properties of a room (where statistical methods in the standards cannot be applied directly) are often hard to estimate due to strong modal behaviour. The situation gets complicated by the fact that variations in the furnishing can have an impact on the modal patterns and therefore can also influence the results of measurements at certain points, in spite of the room properties being the same. The latter can hinder the achievement of acoustic comfort in dwellings, even if they comply with the current regulations, especially due to the fact that low-frequency noise is left outside the scope, since the standards currently in force do not require measurements below 100 Hz (albeit Sweden set 50 Hz as lower limit). This article aims to study variations of the sound field that results of varying the position of three moderately absorbing boards, which emulate how very sparse furniture can impact the sound field when relocated in the room. Furthermore, the potential of numerical models as prediction tools for such problems is pointed out.

Download Full-text

Low-frequency noise and static analysis of the impact of the TiN metal gate thicknesses on n- and p-channel MuGFETs

Solid-State Electronics ◽

10.1016/j.sse.2010.07.007 ◽

2010 ◽

Vol 54 (12) ◽

pp. 1592-1597 ◽

Cited By ~ 7

Author(s):

M. Rodrigues ◽

J.A. Martino ◽

A. Mercha ◽

N. Collaert ◽

E. Simoen ◽

...

Keyword(s):

Static Analysis ◽

Low Frequency ◽

Frequency Noise ◽

Low Frequency Noise ◽

Metal Gate ◽

Tin Metal ◽

The Impact

Download Full-text

Low Frequency Noise Analysis in Advanced CMOS Devices

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.324.441 ◽

2011 ◽

Vol 324 ◽

pp. 441-444 ◽

Cited By ~ 6

Author(s):

Jalal Jomaah ◽

Majida Fadlallah ◽

Gerard Ghibaudo

Keyword(s):

Experimental Data ◽

Noise Analysis ◽

Low Frequency ◽

Deep Submicron ◽

Electrical Noise ◽

Frequency Noise ◽

Low Frequency Noise ◽

Noise Sources ◽

The Impact ◽

Mobility Fluctuations

A review of recent results concerning the low frequency noise in modern CMOS devices is given. The approaches such as the carrier number and the Hooge mobility fluctuations used for the analysis of the noise sources are illustrated through experimental data obtained on advanced CMOS generations. Furthermore, the impact on the electrical noise of the shrinking of CMOS devices in the deep submicron range is also shown.

Download Full-text