Improving ambient noise cross-correlations in the noisy ocean bottom environment of the Juan de Fuca plate

Science.gov (United States)

Tian, Ye; Ritzwoller, Michael H.

2017-09-01

Ambient noise tomography exploits seismic ground motions that propagate coherently over long interstation distances. Such ground motions provide information about the medium of propagation that is recoverable from interstation cross-correlations. Local noise sources, which are particularly strong in ocean bottom environments, corrupt ambient noise cross-correlations and compromise the effectiveness of ambient noise tomography. Based on 62 ocean bottom seismometers (OBSs) located on Juan de Fuca (JdF) plate from the Cascadia Initiative experiment and 40 continental stations near the coast of the western United States obtained in 2011 and 2012, we attempt to reduce the effects of local noise on vertical component seismic records across the plate and onto US continent. The goal is to provide better interstation cross-correlations for use in ambient noise tomography and the study of ambient noise directionality. As shown in previous studies, tilt and compliance noise are major sources of noise that contaminate the vertical channels of the OBSs and such noise can be greatly reduced by exploiting information on the horizontal components and the differential pressure gauge records, respectively. We find that ambient noise cross-correlations involving OBSs are of significantly higher signal-to-noise ratio at periods greater than 10 s after reducing these types of noise, particularly in shallow water environments where tilt and compliance noise are especially strong. The reduction of tilt and compliance noise promises to improve the accuracy and spatial extent of ambient noise tomography, allowing measurements based on coherently propagating ambient noise to be made at stations in the shallower parts of the JdF plate and at longer periods than in previous studies. In addition such local noise reduction produces better estimates of the azimuthal content of ambient noise.

Spatial Correlation in the Ambient Core Noise Field of a Turbofan Engine

Science.gov (United States)

Miles, Jeffrey Hilton

2012-01-01

An acoustic transfer function relating combustion noise and turbine exit noise in the presence of enclosed ambient core noise is investigated using a dynamic system model and an acoustic system model for the particular turbofan engine studied and for a range of operating conditions. Measurements of cross-spectra magnitude and phase between the combustor and turbine exit and auto-spectra at the turbine exit and combustor are used to show the presence of indirect and direct combustion noise over the frequency range of 0 400 Hz. The procedure used evaluates the ratio of direct to indirect combustion noise. The procedure used also evaluates the post-combustion residence time in the combustor which is a factor in the formation of thermal NOx and soot in this region. These measurements are masked by the ambient core noise sound field in this frequency range which is observable since the transducers are situated within an acoustic wavelength of one another. An ambient core noise field model based on one and two dimensional spatial correlation functions is used to replicate the spatially correlated response of the pair of transducers. The spatial correlation function increases measured attenuation due to destructive interference and masks the true attenuation of the turbine.

Separating underwater ambient noise from flow noise recorded on stereo acoustic tags attached to marine mammals

NARCIS (Netherlands)

Benda-Beckmann, A.M. von; Wensveen, P.J.; Samarra, F.I.P.; Beerens, S.P.; Miller, P.J.O.

2016-01-01

Sound-recording acoustic tags attached to marine animals are commonly used in behavioural studies. Measuring ambient noise is of interest to efforts to understand responses of marine mammals to anthropogenic underwater sound, or to assess their communication space. Noise of water flowing around the

Amplification and Attenuation across USArray using Ambient Noise Wavefront Tracking

KAUST Repository

Bowden, Daniel C.

2017-11-15

As seismic travel-time tomography continues to be refined using data from the vast USArray dataset, it is advantageous to also exploit the amplitude information carried by seismic waves. We use ambient noise cross correlation to make observations of surface-wave amplification and attenuation at shorter periods (8 – 32 seconds) than can be observed with only traditional teleseismic earthquake sources. We show that the wavefront tracking approach of [Lin et al., 2012a] can be successfully applied to ambient noise correlations, yielding results quite similar to those from earthquake observations at periods of overlap. This consistency indicates that the wavefront tracking approach is viable for use with ambient noise correlations, despite concerns of the inhomogeneous and unknown distribution of noise sources. The resulting amplification and attenuation maps correlate well with known tectonic and crustal structure; at the shortest periods, our amplification and attenuation maps correlate well with surface geology and known sedimentary basins, while our longest period amplitudes are controlled by crustal thickness and begin to probe upper mantle materials. These amplification and attenuation observations are sensitive to crustal materials in different ways than travel-time observations and may be used to better constrain temperature or density variations. We also value them as an independent means of describing the lateral variability of observed Rayleigh-wave amplitudes without the need for 3D tomographic inversions.

Development of a low cost method to estimate the seismic signature of a geothermal field form ambient noise analysis.

Energy Technology Data Exchange (ETDEWEB)

Tibuleac, Ileana [Univ. of Nevada, Reno, NV (United States)

2016-06-30

A new, cost effective and non-invasive exploration method using ambient seismic noise has been tested at Soda Lake, NV, with promising results. The material included in this report demonstrates that, with the advantage of initial S-velocity models estimated from ambient noise surface waves, the seismic reflection survey, although with lower resolution, reproduces the results of the active survey when the ambient seismic noise is not contaminated by strong cultural noise. Ambient noise resolution is less at depth (below 1000m) compared to the active survey. In general, the results are promising and useful information can be recovered from ambient seismic noise, including dipping features and fault locations.

Improved surface-wave retrieval from ambient seismic noise by multi-dimensional deconvolution

Science.gov (United States)

Wapenaar, Kees; Ruigrok, Elmer; van der Neut, Joost; Draganov, Deyan

2011-01-01

The methodology of surface-wave retrieval from ambient seismic noise by crosscorrelation relies on the assumption that the noise field is equipartitioned. Deviations from equipartitioning degrade the accuracy of the retrieved surface-wave Green's function. A point-spread function, derived from the same ambient noise field, quantifies the smearing in space and time of the virtual source of the Green's function. By multidimensionally deconvolving the retrieved Green's function by the point-spread function, the virtual source becomes better focussed in space and time and hence the accuracy of the retrieved surface-wave Green's function may improve significantly. We illustrate this at the hand of a numerical example and discuss the advantages and limitations of this new methodology.

Three-component ambient noise beamforming in the Parkfield area

Science.gov (United States)

Löer, Katrin; Riahi, Nima; Saenger, Erik H.

2018-06-01

We apply a three-component beamforming algorithm to an ambient noise data set recorded at a seismic array to extract information about both isotropic and anisotropic surface wave velocities. In particular, we test the sensitivity of the method with respect to the array geometry as well as to seasonal variations in the distribution of noise sources. In the earth's crust, anisotropy is typically caused by oriented faults or fractures and can be altered when earthquakes or human activities cause these structures to change. Monitoring anisotropy changes thus provides time-dependent information on subsurface processes, provided they can be distinguished from other effects. We analyse ambient noise data at frequencies between 0.08 and 0.52 Hz recorded at a three-component array in the Parkfield area, California (US), between 2001 November and 2002 April. During this time, no major earthquakes were identified in the area and structural changes are thus not expected. We compute dispersion curves of Love and Rayleigh waves and estimate anisotropy parameters for Love waves. For Rayleigh waves, the azimuthal source coverage is too limited to perform anisotropy analysis. For Love waves, ambient noise sources are more widely distributed and we observe significant and stable surface wave anisotropy for frequencies between 0.2 and 0.4 Hz. Synthetic data experiments indicate that the array geometry introduces apparent anisotropy, especially when waves from multiple sources arrive simultaneously at the array. Both the magnitude and the pattern of apparent anisotropy, however, differ significantly from the anisotropy observed in Love wave data. Temporal variations of anisotropy parameters observed at frequencies below 0.2 Hz and above 0.4 Hz correlate with changes in the source distribution. Frequencies between 0.2 and 0.4 Hz, however, are less affected by these variations and provide relatively stable results over the period of study.

Ambient noise levels in the Taiwan region

Science.gov (United States)

Liang, W.; Liu, C.; Chen, R.; Huang, B.; Wu, F. T.; Wang, C.

2008-12-01

To characterize the island-wide background seismic noise in Taiwan, we estimate the power spectral density (PSD) at broadband stations of both the BATS (Broadband Array in Taiwan for Seismology) and the TAIGER experiment (Apr. 2006~Apr. 2008) for periods ranging from ~0.2 to 100 seconds. A new approach to calculate the probability density functions of noise power (PDFs, MaNamara and Buland, 2004) is used in this study. The results indicate that the cultural noise at higher frequencies is significant at populated area, which shows diurnal and weekly variation as what we expected. The noise power for microseisms centered at a period of ~5 seconds around the western costal plain show ~20dB higher than what observed at eastern Taiwan. This observation supports the inference that the coastal regions having narrow shelf with irregular coastlines are know to be especially efficient at radiating the predominat microseisms. Results from the linear array across central Taiwan demonstrate that the average noise power is quietest at the eastern Central Range. We have mapped the PDF mode for stations at various periods to see the spatial distribution of ambient noise levels, which could be used as the basic information for future station siting. Temporal variation of noise PSD is also present to provide a quantitative description of the seismic data quality collected by both BATS and TAIGER experiment. Some operational problems like base tilt, sensitivity change can be identified easily as well.

Toward predicting clay landslide with ambient seismic noise

Science.gov (United States)

Larose, E. F.; Mainsant, G.; Carriere, S.; Chambon, G.; Michoud, C.; Jongmans, D.; Jaboyedoff, M.

2013-12-01

Clay-rich pose critical problems in risk management worldwide. The most widely proposed mechanism leading to such flow-like movements is the increase in water pore pressure in the sliding mass, generating partial or complete liquefaction. This solid-to-liquid transition results in a dramatic reduction of mechanical rigidity, which could be detected by monitoring shear wave velocity variations, The ambient seismic noise correlation technique has been applied to measure the variation in the seismic surface wave velocity in the Pont Bourquin landslide (Swiss Alps). This small but active composite earthslide-earthflow was equipped with continuously recording seismic sensors during spring and summer 2010, and then again from fall 2011 on. An earthslide of a few thousand cubic meters was triggered in mid-August 2010, after a rainy period. This article shows that the seismic velocity of the sliding material, measured from daily noise correlograms, decreased continuously and rapidly for several days prior to the catastrophic event. From a spectral analysis of the velocity decrease, it was possible to determine the location of the change at the base of the sliding layer. These results are confirmed by analogous small-scale experiments in the laboratory. These results demonstrate that ambient seismic noise can be used to detect rigidity variations before failure and could potentially be used to predict landslides.

Improved surface?wave retrieval from ambient seismic noise by multi?dimensional deconvolution

NARCIS (Netherlands)

Wapenaar, C.P.A.; Ruigrok, E.N.; Van der Neut, J.R.; Draganov, D.S.

2011-01-01

The methodology of surface?wave retrieval from ambient seismic noise by crosscorrelation relies on the assumption that the noise field is equipartitioned. Deviations from equipartitioning degrade the accuracy of the retrieved surface?wave Green's function. A point?spread function, derived from the

Assessment of ambient noise levels in the urban residential streets of Eastern Alexandria, Egypt.

Science.gov (United States)

Zaki, Gehan R

2012-12-01

Street of Alexandria have numerous unplanned, mixed, and noisy activities that may interfere with public health and comfort. The aim of this study was to assess A-weighted ambient noise levels in urban residential streets of Eastern Alexandria, Egypt, from September 2010 to January 2011, with the objective of recommending corrective actions to minimize high noise levels. A descriptive cross-sectional study was carried out, in which A-weighted ambient noise levels were measured on the basis of 24-h periods, using Ono sokki la-5120--precision integrating sound level meter, from September 2010 to January 2011. The measurements were taken on three streets, which were selected using stratified random sampling. Seven measurement sites, along the three streets under study, were selected by site visits according to predetermined criteria. A-weighted ambient noise levels (LAeq) were the highest [70.7 (24.2) dB] on high-traffic-density and high-human-activity streets followed by streets with moderate and low traffic density and human activity [67.5 (31.3) and 62.8 (38.2) dB], respectively. It varied significantly depending on means of transportation (road traffic, train, and/or tram) and human activities (parking lots, shops, and/or street merchants). The A-weighted ambient noise levels on urban residential streets of Eastern Alexandria, Egypt, exceeded the Egyptian National Standards during the three periods of the day (daytime, evening, and night), except in some relatively quiet locations during the night. Consequently, remedial actions to reduce noise levels were recommended.

Amplification and Attenuation across USArray using Ambient Noise Wavefront Tracking

KAUST Repository

Bowden, Daniel C.; Tsai, Victor C.; Lin, Fan-Chi

2017-01-01

As seismic travel-time tomography continues to be refined using data from the vast USArray dataset, it is advantageous to also exploit the amplitude information carried by seismic waves. We use ambient noise cross correlation to make observations

Ambient noise forecasting with a large acoustic array in a complex shallow water environment.

Science.gov (United States)

Rogers, Jeffrey S; Wales, Stephen C; Means, Steven L

2017-11-01

Forecasting ambient noise levels in the ocean can be a useful way of characterizing the detection performance of sonar systems and projecting bounds on performance into the near future. The assertion is that noise forecasting can be improved with a priori knowledge of source positions coupled with the ability to resolve closely separated sources in bearing. One example of such a system is the large aperture research array located at the South Florida Test Facility. Given radar and Automatic Identification System defined source positions and environmental information, transmission loss (TL) is computed from known source positions to the array. Source levels (SLs) of individual ships are then estimated from computed TL and the pre-determined beam response of the array using a non-negative least squares algorithm. Ambient noise forecasts are formed by projecting the estimated SLs along known ship tracks. Ambient noise forecast estimates are compared to measured beam level data and mean-squared error is computed. A mean squared error as low as 3.5 dB is demonstrated in 30 min forecast estimates when compared to ground truth.

Wind dependence of ambient noise in a biologically rich coastal area.

Science.gov (United States)

Mathias, Delphine; Gervaise, Cédric; Di Iorio, Lucia

2016-02-01

The wind dependence of acoustic spectrum between 100 Hz and 16 kHz is investigated for coastal biologically rich areas. The analysis of 5 months of continuous measurements run in a 10 m deep shallow water environment off Brittany (France) showed that wind dependence of spectral levels is subject to masking by biological sounds. When dealing with raw data, the wind dependence of spectral levels was not significant for frequencies where biological sounds were present (2 to 10 kHz). An algorithm developed by Kinda, Simard, Gervaise, Mars, and Fortier [J. Acoust. Soc. Am. 134(1), 77-87 (2013)] was used to automatically filter out the loud distinctive biological contribution and estimated the ambient noise spectrum. The wind dependence of ambient noise spectrum was always significant after application of this filter. A mixture model for ambient noise spectrum which accounts for the richness of the soundscape is proposed. This model revealed that wind dependence holds once the wind speed was strong enough to produce sounds higher in amplitude than the biological chorus (9 kn at 3 kHz, 11 kn at 8 kHz). For these higher wind speeds, a logarithmic affine law was adequate and its estimated parameters were compatible with previous studies (average slope 27.1 dB per decade of wind speed increase).

Crustal structure of Australia from ambient seismic noise tomography

Science.gov (United States)

Saygin, Erdinc; Kennett, B. L. N.

2012-01-01

Surface wave tomography for Australian crustal structure has been carried out using group velocity measurements in the period range 1-32 s extracted from stacked correlations of ambient noise between station pairs. Both Rayleigh wave and Love wave group velocity maps are constructed for each period using the vertical and transverse component of the Green's function estimates from the ambient noise. The full suite of portable broadband deployments and permanent stations on the continent have been used with over 250 stations in all and up to 7500 paths. The permanent stations provide a useful link between the various shorter-term portable deployments. At each period the group velocity maps are constructed with a fully nonlinear tomographic inversion exploiting a subspace technique and the Fast Marching Method for wavefront tracking. For Rayleigh waves the continental coverage is good enough to allow the construction of a 3D shear wavespeed model in a two stage approach. Local group dispersion information is collated for a distribution of points across the continent and inverted for a 1D SV wavespeed profile using a Neighbourhood Algorithm method. The resulting set of 1D models are then interpolated to produce the final 3D wavespeed model. The group velocity maps show the strong influence of thick sediments at shorter periods, and distinct fast zones associated with cratonic regions. Below the sediments the 3D shear wavespeed model displays significant heterogeneity with only moderate correlation with surface tectonic features. For example, there is no evident expression of the Tasman Line marking the eastern edge of Precambrian outcrop. The large number of available inter-station paths extracted from the ambient noise analysis provide detailed shear wavespeed information for crustal structure across the Australian continent for the first time, including regions where there was no prior sampling because of difficult logistics.

Ambient air pollution, traffic noise and adult asthma prevalence : A BioSHaRE approach

NARCIS (Netherlands)

Cai, Yutong; Zijlema, Wilma L.; Doiron, Dany; Blangiardo, Marta; Burton, Paul R.; Fortier, Isabel; Gaye, Amadou; Gulliver, John; de Hoogh, Kees; Hveem, Kristian; Mbatchou, Stephane; Morley, David W; Stolk, Ronald P.; Elliott, Paul; Hansell, Anna L.; Hodgson, Susan

2017-01-01

We investigated the effects of both ambient air pollution and traffic noise on adult asthma prevalence, using harmonised data from three European cohort studies established in 2006-2013 (HUNT3, Lifelines and UK Biobank). Residential exposures to ambient air pollution (particulate matter with

Upper crustal structure of Madeira Island revealed from ambient noise tomography

Science.gov (United States)

Matos, Catarina; Silveira, Graça; Matias, Luís; Caldeira, Rita; Ribeiro, M. Luísa; Dias, Nuno A.; Krüger, Frank; Bento dos Santos, Telmo

2015-06-01

We present the first image of the Madeira upper crustal structure, using ambient seismic noise tomography. 16 months of ambient noise, recorded in a dense network of 26 seismometers deployed across Madeira, allowed reconstructing Rayleigh wave Green's functions between receivers. Dispersion analysis was performed in the short period band from 1.0 to 4.0 s. Group velocity measurements were regionalized to obtain 2D tomographic images, with a lateral resolution of 2.0 km in central Madeira. Afterwards, the dispersion curves, extracted from each cell of the 2D group velocity maps, were inverted as a function of depth to obtain a 3D shear wave velocity model of the upper crust, from the surface to a depth of 2.0 km. The obtained 3D velocity model reveals features throughout the island that correlates well with surface geology and island evolution.

Ambient noise tomography of Lo'ihi

Science.gov (United States)

McClement, K.; Thurber, C. H.; Teel, A.; Caplan-Auerbach, J.

2012-12-01

Lo'ihi seamount, the youngest volcano in the Hawaiian-Emperor chain, lies approximately 30 km south of Hawai'i Island with its summit still approximately 1 km below sea level. Lo'ihi offers a unique opportunity to study the early formation of a hotspot volcano and can provide insight into the deep internal structure of the other volcanoes that make up the Hawaiian Islands. This study uses Ambient Noise Tomography (ANT) to create a 3D tomographic image of Lo'ihi's S-wave velocity structure from ocean bottom seismometer (OBS) data. ANT has been used in many subaerial studies but has seen very few applications to OBS data. This study uses continuous data recorded in 2010 to 2011 from 12 short-period OBS instruments deployed on and around Lo'ihi. With the farthest distance between stations being just over 30 km, the stations provide a fairly dense coverage mainly for the northern half of the volcano. Following the approach of Masterlark et al. [2010], we computed vertical-vertical and vertical-radial cross-correlations using 97 days of continuous data from the 12 stations to produce the ambient noise Green's functions. From these, dispersion curves were produced over a frequency range from .04 Hz to 0.65 Hz . After a quality control analysis, checkerboard tests were used to determine a suitable cell size for the 2D group velocity inversions. The final step is the inversion of the group velocity dispersion curves to create a 3D Vs model. The 3D Vs image produced through this method does not provide clear evidence of a shallow magma chamber; however, when compared to a previous P-wave velocity (Vp) model [Caplan-Auerbach, 2001], a high Vp/Vs ratio is evident especially at depths from 1 km to 5 km, indicating the presence of highly fractured rock.

Spatial Vertical Directionality and Correlation of Low-Frequency Ambient Noise in Deep Ocean Direct-Arrival Zones

Directory of Open Access Journals (Sweden)

Qiulong Yang

2018-01-01

Full Text Available Wind-driven and distant shipping noise sources contribute to the total noise field in the deep ocean direct-arrival zones. Wind-driven and distant shipping noise sources may significantly and simultaneously affect the spatial characteristics of the total noise field to some extent. In this work, a ray approach and parabolic equation solution method were jointly utilized to model the low-frequency ambient noise field in a range-dependent deep ocean environment by considering their calculation accuracy and efficiency in near-field wind-driven and far-field distant shipping noise fields. The reanalysis databases of National Center of Environment Prediction (NCEP and Volunteer Observation System (VOS were used to model the ambient noise source intensity and distribution. Spatial vertical directionality and correlation were analyzed in three scenarios that correspond to three wind speed conditions. The noise field was dominated by distant shipping noise sources when the wind speed was less than 3 m/s, and then the spatial vertical directionality and vertical correlation of the total noise field were nearly consistent with those of distant shipping noise field. The total noise field was completely dominated by near field wind generated noise sources when the wind speed was greater than 12 m/s at 150 Hz, and then the spatial vertical correlation coefficient and directionality pattern of the total noise field was approximately consistent with that of the wind-driven noise field. The spatial characteristics of the total noise field for wind speeds between 3 m/s and 12 m/s were the weighted results of wind-driven and distant shipping noise fields. Furthermore, the spatial characteristics of low-frequency ambient noise field were compared with the classical Cron/Sherman deep water noise field coherence function. Simulation results with the described modeling method showed good agreement with the experimental measurement results based on the vertical line

Spatial Vertical Directionality and Correlation of Low-Frequency Ambient Noise in Deep Ocean Direct-Arrival Zones

Science.gov (United States)

Yang, Qiulong; Yang, Kunde; Cao, Ran; Duan, Shunli

2018-01-01

Wind-driven and distant shipping noise sources contribute to the total noise field in the deep ocean direct-arrival zones. Wind-driven and distant shipping noise sources may significantly and simultaneously affect the spatial characteristics of the total noise field to some extent. In this work, a ray approach and parabolic equation solution method were jointly utilized to model the low-frequency ambient noise field in a range-dependent deep ocean environment by considering their calculation accuracy and efficiency in near-field wind-driven and far-field distant shipping noise fields. The reanalysis databases of National Center of Environment Prediction (NCEP) and Volunteer Observation System (VOS) were used to model the ambient noise source intensity and distribution. Spatial vertical directionality and correlation were analyzed in three scenarios that correspond to three wind speed conditions. The noise field was dominated by distant shipping noise sources when the wind speed was less than 3 m/s, and then the spatial vertical directionality and vertical correlation of the total noise field were nearly consistent with those of distant shipping noise field. The total noise field was completely dominated by near field wind generated noise sources when the wind speed was greater than 12 m/s at 150 Hz, and then the spatial vertical correlation coefficient and directionality pattern of the total noise field was approximately consistent with that of the wind-driven noise field. The spatial characteristics of the total noise field for wind speeds between 3 m/s and 12 m/s were the weighted results of wind-driven and distant shipping noise fields. Furthermore, the spatial characteristics of low-frequency ambient noise field were compared with the classical Cron/Sherman deep water noise field coherence function. Simulation results with the described modeling method showed good agreement with the experimental measurement results based on the vertical line array deployed near

The effects of music, white noise, and ambient noise on sedation and anxiety in patients under spinal anesthesia during surgery.

Science.gov (United States)

Ilkkaya, Nazan Koylu; Ustun, Faik Emre; Sener, Elif Bengi; Kaya, Cengiz; Ustun, Yasemin Burcu; Koksal, Ersin; Kocamanoglu, Ismail Serhat; Ozkan, Fatih

2014-10-01

To compare effects of music, white noise, and ambient (background) noise on patient anxiety and sedation. Open, parallel, and randomized controlled trial. Seventy-five patients aged 18 to 60 years who were scheduled for surgical procedures under spinal anesthesia were randomly assigned to ambient noise (Group O), white noise (Group B), or music groups (Group M). We evaluated patients' anxiety and sedation levels via the Observer's Assessment of Alertness/Sedation (OAA/S) scale and the State-Trait Anxiety Inventory (STAI) questionnaire. At 5 minutes before surgery, the STAI-State Anxiety Inventory (SA) value was significantly lower in Group M than the other groups. At 30-minute recovery, Group M showed significantly lower STAI-SA values than the other groups. Patient satisfaction was highest in Group M. OAA/S values were not significantly different between groups during any period (P > .05). We suggest that patient-selected music reduces perioperative anxiety and contributes to patient satisfaction during the perioperative period. Copyright © 2014 American Society of PeriAnesthesia Nurses. Published by Elsevier Inc. All rights reserved.

Studies of ambient noise in shallow water environments off Mexico and Alaska: characteristics, metrics and time-synchronization applications

Science.gov (United States)

Guerra, Melania

Sound in the ocean originates from multiple mechanisms, both natural and anthropogenic. Collectively, underwater ambient noise accumulates valuable information about both its sources and the oceanic environment that propagates this noise. Characterizing the features of ambient noise source mechanisms is challenging, but essential, for properly describing an acoustic environment. Disturbances to a local acoustic environment may affect many aquatic species that have adapted to be heavily dependent on this particular sense for survival functions. In the case of marine mammals, which are federally protected, demand exists for understanding such potential impacts, which drives important scientific efforts that utilize passive acoustic monitoring (PAM) tools to inform regulatory decisions. This dissertation presents two independent studies that use PAM data to investigate the characteristics of source mechanisms that dominate ambient noise in two diverse shallow water environments. The study in Chapter 2 directly addresses the concern of how anthropogenic activities can degrade the effectiveness of PAM. In the Alaskan Beaufort Sea, an environment where ambient noise is normally dominated by natural causes, seismic surveys create impulsive sounds to map the composition of the bottom. By inspecting single-sensor PAM data, the spectral characteristics of seismic survey airgun reverberation are measured, and their contribution to the overall ambient noise is quantified. This work is relevant to multiple ongoing mitigation protocols that rely on PAM to acoustically detect marine mammal presence during industrial operations. Meanwhile, Chapter 3 demonstrates that by analyzing data from multiple PAM sensors, features embedded in both directional and omnidirectional ambient noise can be used to develop new time-synchronization processing techniques for aligning autonomous elements of an acoustic array, a tool commonly used in PAM for detecting and tracking marine mammals. Using

Ambient air pollution, traffic noise and adult asthma prevalence: a BioSHaRE approach.

Science.gov (United States)

Cai, Yutong; Zijlema, Wilma L; Doiron, Dany; Blangiardo, Marta; Burton, Paul R; Fortier, Isabel; Gaye, Amadou; Gulliver, John; de Hoogh, Kees; Hveem, Kristian; Mbatchou, Stéphane; Morley, David W; Stolk, Ronald P; Elliott, Paul; Hansell, Anna L; Hodgson, Susan

2017-01-01

We investigated the effects of both ambient air pollution and traffic noise on adult asthma prevalence, using harmonised data from three European cohort studies established in 2006-2013 (HUNT3, Lifelines and UK Biobank).Residential exposures to ambient air pollution (particulate matter with aerodynamic diameter ≤10 µm (PM 10 ) and nitrogen dioxide (NO 2 )) were estimated by a pan-European Land Use Regression model for 2007. Traffic noise for 2009 was modelled at home addresses by adapting a standardised noise assessment framework (CNOSSOS-EU). A cross-sectional analysis of 646 731 participants aged ≥20 years was undertaken using DataSHIELD to pool data for individual-level analysis via a "compute to the data" approach. Multivariate logistic regression models were fitted to assess the effects of each exposure on lifetime and current asthma prevalence.PM 10 or NO 2 higher by 10 µg·m -3 was associated with 12.8% (95% CI 9.5-16.3%) and 1.9% (95% CI 1.1-2.8%) higher lifetime asthma prevalence, respectively, independent of confounders. Effects were larger in those aged ≥50 years, ever-smokers and less educated. Noise exposure was not significantly associated with asthma prevalence.This study suggests that long-term ambient PM 10 exposure is associated with asthma prevalence in western European adults. Traffic noise is not associated with asthma prevalence, but its potential to impact on asthma exacerbations needs further investigation. Copyright ©ERS 2017.

Origin of the chemical noise in ambient mass spectrometry

International Nuclear Information System (INIS)

Yang Shuiping; Zhu Zhiqiang; Huang Longzhu; Zhang Xinglei; Zhu Tenggao; Chen Huanwen

2012-01-01

The instrumental background of ambient mass spectrometry, (API-MS) is analyzed and the possible potential origins of the background noise is identified. According to the mass spectra obtained using the API-MS instruments by different manufacturers, the characteristic fragment ions all indicated that the background noise are resulted from the phthalates such as diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), bis (2-ethylhexyl) phthalate (DEHP), and silicones such as decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). These chemicals are probably released from the polymeric materials used in the ionization sources, such as O-type sealing ring etc. In addition, the instrumental background has to be considered especially during the analysis of phthalate and peptide compounds. (authors)

Noiseonomics: the relationship between ambient noise levels in the sea and global economic trends.

Science.gov (United States)

Frisk, George V

2012-01-01

In recent years, the topic of noise in the sea and its effects on marine mammals has attracted considerable attention from both the scientific community and the general public. Since marine mammals rely heavily on acoustics as a primary means of communicating, navigating, and foraging in the ocean, any change in their acoustic environment may have an impact on their behavior. Specifically, a growing body of literature suggests that low-frequency, ambient noise levels in the open ocean increased approximately 3.3 dB per decade during the period 1950-2007. Here we show that this increase can be attributed primarily to commercial shipping activity, which in turn, can be linked to global economic growth. As a corollary, we conclude that ambient noise levels can be directly related to global economic conditions. We provide experimental evidence supporting this theory and discuss its implications for predicting future noise levels based on global economic trends.

The crustal structure beneath The Netherlands derived from ambient seismic noise

NARCIS (Netherlands)

Yudistira, Tedi; Paulssen, Hanneke; Trampert, Jeannot

2017-01-01

This work presents the first comprehensive 3-D model of the crust beneath The Netherlands. To obtain this model, we designed the NARS-Netherlands project, a dense deployment of broadband stations in the area. Rayleigh and Love wave group velocity dispersion was measured from ambient noise

Ambient noise levels and characterization in Aegean region, Turkey

Science.gov (United States)

Sevim, Fatih; Zor, Ekrem; Açıkgöz, Cem; Tarancıoğlu, Adil

2018-03-01

We assessed the ambient noise level in the Aegean region and analyzed its diurnal variation and its relation to the earthquake detection capability of the Aegean Region Seismic Network (ARSN). We prepared probability density functions (PDFs) for 19 broadband stations in the Aegean region operated by the Earth and Marine Sciences Institute (EMSI) of the Marmara Research Center (MRC) of the Turkish Scientific Research Council (TÜBİTAK). The power spectral densities (PSDs) used to construct PDFs for each station were computed for the periods between 0.02 and 180 s. In addition, we generated noise map of the Aegean region for different periods using the PDFs to assess the origin of the noise. We analyzed earthquake activity in the region and found that there are more local events recorded at night than during the day for each station. This difference is strongly related to diurnal variation of background noise level for the period range mostly covering the frequency range for the local events. We observed daytime noise level 15 to 20 dB higher than that at the nighttime in high frequencies for almost all stations caused by its proximity to settled areas and roads. Additionally, we observed a splitting peak within the Double Frequency (DF) microseism band; it showed a clear noise increase around the short period DF band at all the stations, decreasing inland. This peak may be related to sea waves locally generated in the Aegean Sea. We also identified a prominent increase related to marble saw companies in some stations' noise PDFs.

Optimal filter design for shielded and unshielded ambient noise reduction in fetal magnetocardiography

International Nuclear Information System (INIS)

Comani, S; Mantini, D; Alleva, G; Luzio, S Di; Romani, G L

2005-01-01

The greatest impediment to extracting high-quality fetal signals from fetal magnetocardiography (fMCG) is environmental magnetic noise, which may have peak-to-peak intensity comparable to fetal QRS amplitude. Being an unstructured Gaussian signal with large disturbances at specific frequencies, ambient field noise can be reduced with hardware-based approaches and/or with software algorithms that digitally filter magnetocardiographic recordings. At present, no systematic evaluation of filters' performances on shielded and unshielded fMCG is available. We designed high-pass and low-pass Chebychev II-type filters with zero-phase and stable impulse response; the most commonly used band-pass filters were implemented combining high-pass and low-pass filters. The achieved ambient noise reduction in shielded and unshielded recordings was quantified, and the corresponding signal-to-noise ratio (SNR) and signal-to-distortion ratio (SDR) of the retrieved fetal signals was evaluated. The study regarded 66 fMCG datasets at different gestational ages (22-37 weeks). Since the spectral structures of shielded and unshielded magnetic noise were very similar, we concluded that the same filter setting might be applied to both conditions. Band-pass filters (1.0-100 Hz) and (2.0-100 Hz) provided the best combinations of fetal signal detection rates, SNR and SDR; however, the former should be preferred in the case of arrhythmic fetuses, which might present spectral components below 2 Hz

Ambient seismic noise monitoring of a clay landslide: Toward failure prediction

Science.gov (United States)

Mainsant, Guénolé; Larose, Eric; Brönnimann, Cornelia; Jongmans, Denis; Michoud, Clément; Jaboyedoff, Michel

2012-03-01

Given that clay-rich landslides may become mobilized, leading to rapid mass movements (earthflows and debris flows), they pose critical problems in risk management worldwide. The most widely proposed mechanism leading to such flow-like movements is the increase in water pore pressure in the sliding mass, generating partial or complete liquefaction. This solid-to-liquid transition results in a dramatic reduction of mechanical rigidity in the liquefied zones, which could be detected by monitoring shear wave velocity variations. With this purpose in mind, the ambient seismic noise correlation technique has been applied to measure the variation in the seismic surface wave velocity in the Pont Bourquin landslide (Swiss Alps). This small but active composite earthslide-earthflow was equipped with continuously recording seismic sensors during spring and summer 2010. An earthslide of a few thousand cubic meters was triggered in mid-August 2010, after a rainy period. This article shows that the seismic velocity of the sliding material, measured from daily noise correlograms, decreased continuously and rapidly for several days prior to the catastrophic event. From a spectral analysis of the velocity decrease, it was possible to determine the location of the change at the base of the sliding layer. These results demonstrate that ambient seismic noise can be used to detect rigidity variations before failure and could potentially be used to predict landslides.

First results of cross-correlation analysis of ambient seismic noise from the Hellenic Unified Seismic Network

NARCIS (Netherlands)

Panou, Areti; Paulssen, Hanneke; Hatzidimitriou, Panagiotis

2015-01-01

In this study we present phase velocity maps that were obtained from the cross-correlation analysis of ambient seismic noise recorded in the region of Greece.We used one year (2013) of ambient seismic data obtained from the vertical component of 64 broadband permanent seismological stations that are

Shear-wave velocity of marine sediments offshore Taiwan using ambient seismic noise

Science.gov (United States)

Lin, Yu-Tse; Lin, Jing-Yi; Kuo-Chen, Hao; Yeh, Yi-Chin; Cheng, Win-Bin

2017-04-01

Seismic ambient noise technology has many advantages over the traditional two-station method. The most important one is that noise is happening all the time and it can be widely and evenly distributed. Thus, the Green's Function of any station pair can be obtained through the data cross-correlation process. Many related studies have been performed to estimate the velocity structures based on the inland area. Only a few studies were reported for the marine area due to the relatively shorter recording time of ocean bottom seismometers (OBS) deployment and the high cost of the marine experiment. However, the understanding about the shear-wave velocity (Vs) of the marine sediments is very crucial for the hazard assessment related to submarine landslides, particularly with the growing of submarine resources exploration. In this study, we applied the ambient noise technique to four OBS seismic networks located offshore Taiwan in the aim of getting more information about the noise sources and having the preliminary estimation for the Vs of the marine sediments. Two of the seismic networks were deployed in the NE part of Taiwan, near the Ryukyu subduction system, whereas the others were in the SW area, on the continental margin rich in gas hydrate. Generally, ambient seismic noise could be associated with wind, ocean waves, rock fracturing and anthropogenic activity. In the southwestern Taiwan, the cross-correlation function obtained from two seismic networks indicate similar direction, suggestion that the source from the south part of the network could be the origin of the noise. However, the two networks in the northeastern Taiwan show various source direction, which could be caused by the abrupt change of bathymetry or the volcanic degassing effect frequently observed by the marine geophysical method in the area. The Vs determined from the dispersion curve shows a relatively higher value for the networks in the Okinawa Trough (OT) off NE Taiwan than that in the

The Effects of Ambient Conditions on Helicopter Rotor Source Noise Modeling

Science.gov (United States)

Schmitz, Frederic H.; Greenwood, Eric

2011-01-01

A new physics-based method called Fundamental Rotorcraft Acoustic Modeling from Experiments (FRAME) is used to demonstrate the change in rotor harmonic noise of a helicopter operating at different ambient conditions. FRAME is based upon a non-dimensional representation of the governing acoustic and performance equations of a single rotor helicopter. Measured external noise is used together with parameter identification techniques to develop a model of helicopter external noise that is a hybrid between theory and experiment. The FRAME method is used to evaluate the main rotor harmonic noise of a Bell 206B3 helicopter operating at different altitudes. The variation with altitude of Blade-Vortex Interaction (BVI) noise, known to be a strong function of the helicopter s advance ratio, is dependent upon which definition of airspeed is flown by the pilot. If normal flight procedures are followed and indicated airspeed (IAS) is held constant, the true airspeed (TAS) of the helicopter increases with altitude. This causes an increase in advance ratio and a decrease in the speed of sound which results in large changes to BVI noise levels. Results also show that thickness noise on this helicopter becomes more intense at high altitudes where advancing tip Mach number increases because the speed of sound is decreasing and advance ratio increasing for the same indicated airspeed. These results suggest that existing measurement-based empirically derived helicopter rotor noise source models may give incorrect noise estimates when they are used at conditions where data were not measured and may need to be corrected for mission land-use planning purposes.

Ambient Noise Levels in Acute Neonatal Intensive Care Unit of a Tertiary Referral Hospital

OpenAIRE

Sonia R. B D'Souza; Leslie Edward Lewis; Vijay Kumar; Ramesh Bhat Y; Jayashree Purkayastha; Hari Prakash

2017-01-01

Background: Advances in neonatal care have resulted in improved survival of neonates admitted to the intensive care of the Neonatal Intensive Care Unit (NICU). However, the NCU may be an inappropriate milieu, with presence of overwhelming stimuli, most potent being the continuous presence of noise in the ambience of the NICU. Aim and Objectives: To determine and describe the ambient noise levels in the acute NICU of a tertiary referral hospital. Material and Methods...

3-component beamforming analysis of ambient seismic noise field for Love and Rayleigh wave source directions

Science.gov (United States)

Juretzek, Carina; Hadziioannou, Céline

2014-05-01

Our knowledge about common and different origins of Love and Rayleigh waves observed in the microseism band of the ambient seismic noise field is still limited, including the understanding of source locations and source mechanisms. Multi-component array methods are suitable to address this issue. In this work we use a 3-component beamforming algorithm to obtain source directions and polarization states of the ambient seismic noise field within the primary and secondary microseism bands recorded at the Gräfenberg array in southern Germany. The method allows to distinguish between different polarized waves present in the seismic noise field and estimates Love and Rayleigh wave source directions and their seasonal variations using one year of array data. We find mainly coinciding directions for the strongest acting sources of both wave types at the primary microseism and different source directions at the secondary microseism.

Noiseonomics: The relationship between ambient noise levels in the sea and global economic trends

OpenAIRE

Frisk, George V.

2012-01-01

In recent years, the topic of noise in the sea and its effects on marine mammals has attracted considerable attention from both the scientific community and the general public. Since marine mammals rely heavily on acoustics as a primary means of communicating, navigating, and foraging in the ocean, any change in their acoustic environment may have an impact on their behavior. Specifically, a growing body of literature suggests that low-frequency, ambient noise levels in the open ocean increas...

Music and ambient operating room noise in patients undergoing spinal anesthesia.

Science.gov (United States)

Ayoub, Chakib M; Rizk, Laudi B; Yaacoub, Chadi I; Gaal, Dorothy; Kain, Zeev N

2005-05-01

Previous studies have indicated that music decreases intraoperative sedative requirements in patients undergoing surgical procedures under regional anesthesia. In this study we sought to determine whether this decrease in sedative requirements results from music or from eliminating operating room (OR) noise. A secondary aim of the study was to examine the relationship of response to intraoperative music and participants' culture (i.e., American versus Lebanese). Eighty adults (36 American and 54 Lebanese) undergoing urological procedures with spinal anesthesia and patient-controlled IV propofol sedation were randomly assigned to intraoperative music, white noise, or OR noise. We found that, controlling for ambient OR noise, intraoperative music decreases propofol requirements (0.004 +/- 0.002 mg . kg(-1) . min(-1) versus 0.014 +/- 0.004 mg . kg(-1) . min(-1) versus 0.012 +/- 0.002 mg . kg(-1) . min(-1); P = 0.026). We also found that, regardless of group assignment, Lebanese patients used less propofol as compared with American patients (0.005 +/- 0.001 mg . kg(-1) . min(-1) versus 0.017 +/- 0.003 mg . kg(-1) . min(-1); P = 0.001) and that, in both sites, patients in the music group required less propofol (P noise, intraoperative music decreases propofol requirements of both Lebanese and American patients who undergo urological surgery under spinal anesthesia.

Ambient Seismic Noise Tomography of a Loess High Bank at Dunaszekcső (Hungary)

Czech Academy of Sciences Publication Activity Database

Szanyi, G.; Gráczer, Z.; Györi, E.; Kaláb, Zdeněk; Lednická, Markéta

2016-01-01

Roč. 173, č. 8 (2016), s. 2913-2928 ISSN 0033-4553 Institutional support: RVO:68145535 Keywords : seismic interferometry * ambient noise * group velocity * tomography * landslide * high bank Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.591, year: 2016 http://link.springer.com/article/10.1007/s00024-016-1304-1

Imaging Subsurface Structure of Central Zagros Zone/Iran Using Ambient Noise Tomography

Science.gov (United States)

Vahidravesh, Shaghayegh; Pakzad, Mehrdad, ,, Dr.; Hatami, Mohammad Reza, ,, Dr.

2017-04-01

The Central Zagros zone, of west Iran & east Iraq, is surrounded by many active faults (including Main Zagros Reversed Fault, Main Recent Fault, High Zagros Fault, Zagros Fold, & Thrust Belt). Recent studies show that cross-correlation of a long-term ambient seismic noise data recorded in station-pair, includes important information regarding empirical Green's functions (EGFs) between stations. Hence, ambient seismic noise carries valuable information of the wave propagation path (which can be extracted). The 2D model of surface waves (Rayleigh & Love) velocities for the studied area is obtained by seismic ambient noise tomography (ANT) method. Throughout this research, we use continuous records of all three vertical, radial, and tangential components (obtained by rotation) recorded by IRSC (Iranian Seismological Center) and IIEES (International Institute of Earthquake Engineering) networks for this area of interest. The IRSC & IIEES networks are equipped by SS-1 kinematics and Guralp CMG-3T sensors respectively. Data of 20 stations were used for 12 months from 2014/Nov. to 2015/Nov. The performed data processing is similar to the one, put into words in detail by Bensen et al. (2007) including the processed daily base data. Mean, trend, and instrument response were removed and the data were decimated to 5 sps (sample per second) to reduce the amount of storage space and computational time required. We then applied merge to handle data gaps. One-bit time-domain normalization was also applied to suppress the influence of instrument irregularities and earthquake signals followed by spectral (frequency-domain) normalization between 0.05-0.2 Hz (period 5-20 sec). After cross-correlation (processing step), we perform rms stacking (new approach of stacking) to stack many cross-correlation functions based on the highest energy in a time interval which we accordingly anticipate to receive Rayleigh & Love waves fundamental modes. To evaluate quality of the stacking process

Two-receiver measurements of phase velocity: cross-validation of ambient-noise and earthquake-based observations

NARCIS (Netherlands)

Kästle, Emanuel D.; Soomro, Riaz; Weemstra, C.; Boschi, Lapo; Meier, Thomas

2016-01-01

Phase velocities derived from ambient-noise cross-correlation are compared with phase velocities calculated from cross-correlations of waveform recordings of teleseismic earthquakes whose epicentres are approximately on the station–station great circle. The comparison is conducted both for Rayleigh

Impact of wind on ambient noise recorded by the "13 BB star" seismic array in northern Poland

Science.gov (United States)

Lepore, Simone; Markowicz, Krzysztof; Grad, Marek

2016-04-01

Seismic interferometry and beam forming techniques were applied to ambient noise recorded during January 2014 at the "13 BB star" array, composed of thirteen seismic stations located in northern Poland, with the aim of evaluating the azimuth of noise sources and the velocities of surface waves. After normalizing the raw recordings in time and frequency domain, the spectral characteristics of the ambient noise were studied to choose a frequency band suitable for the waves' retrieval. To get the velocity of surface waves by seismic interferometry, the crosscorrelation between all station pairs was analysed for the vertical and horizontal components in the 0.05-0.1 Hz, 0.1-1 Hz and 1 10 Hz frequency bands. For each pair, the crosscorrelation was applied to one hour recordings extracted from the ambient noise. The obtained traces were calculated for a complete day, and then summed together: the daily results were stacked for the whole January 2014. In the lowest frequency range, most of the energy is located around the 3.0 km/s line, meaning that the surface waves coming from the uppermost mantle will be retrieved. The intermediate frequency range shows most of the energy between the 2.0 km/s and 1.5 km/s lines: consequently, surface waves originating from the crust will be retrieved. In the highest frequency range, the surface waves are barely visible on the crosscorrelation traces, implying that the associated energy is strongly attenuated. The azimuth variation associated to the noise field was evaluated by means of the beam forming method, using the data from the whole array for all the three components. To that, the beam power was estimated in a small range of frequencies every day for the whole month. For each day, one hour long results of beam forming applications were stacked together. To avoid aliasing and near field effects, the minimum frequency was set at 0.05 Hz and the maximum to 0.1 Hz. In this frequency band, the amplitude maximum was sought

Passive detection and localization of fatigue cracking in aluminum plates using Green's function reconstruction from ambient noise.

Science.gov (United States)

Yang, Yang; Xiao, Li; Qu, Wenzhong; Lu, Ye

2017-11-01

Recent theoretical and experimental studies have demonstrated that a local Green's function can be retrieved from the cross-correlation of ambient noise field. This technique can be used to detect fatigue cracking in metallic structures, owing to the fact that the presence of crack can lead to a change in Green's function. This paper presents a method of structural fatigue cracking characterization method by measuring Green's function reconstruction from noise excitation and verifies the feasibility of crack detection in poor noise source distribution. Fatigue cracks usually generate nonlinear effects, in which different wave amplitudes and frequency compositions can cause different nonlinear responses. This study also undertakes analysis of the capacity of the proposed approach to identify fatigue cracking under different noise amplitudes and frequency ranges. Experimental investigations of an aluminum plate are conducted to assess the cross-correlations of received noise between sensor pairs and finally to detect the introduced fatigue crack. A damage index is proposed according to the variation between cross-correlations obtained from the pristine crack closed state and the crack opening-closure state when sufficient noise amplitude is used to generate nonlinearity. A probability distribution map of damage is calculated based on damage indices. The fatigue crack introduced in the aluminum plate is successfully identified and oriented, verifying that a fatigue crack can be detected by reconstructing Green's functions from an imperfect diffuse field in which ambient noise sources exist locally. Copyright © 2017 Elsevier B.V. All rights reserved.

Body Wave and Ambient Noise Tomography of Makushin Volcano, Alaska

Science.gov (United States)

Lanza, F.; Thurber, C. H.; Syracuse, E. M.; Ghosh, A.; LI, B.; Power, J. A.

2017-12-01

Located in the eastern portion of the Alaska-Aleutian subduction zone, Makushin Volcano is among the most active volcanoes in the United States and has been classified as high threat based on eruptive history and proximity to the City of Unalaska and international air routes. In 2015, five individual seismic stations and three mini seismic arrays of 15 stations each were deployed on Unalaska island to supplement the Alaska Volcano Observatory (AVO) permanent seismic network. This temporary array was operational for one year. Taking advantage of the increased azimuthal coverage and the array's increased earthquake detection capability, we developed body-wave Vp and Vp/Vs seismic images of the velocity structure beneath the volcano. Body-wave tomography results show a complex structure with the upper 5 km of the crust dominated by both positive and negative Vp anomalies. The shallow high-Vp features possibly delineate remnant magma pathways or conduits. Low-Vp regions are found east of the caldera at approximately 6-9 km depth. This is in agreement with previous tomographic work and geodetic models, obtained using InSAR data, which had identified this region as a possible long-term source of magma. We also observe a high Vp/Vs feature extending between 7 and 12 km depth below the caldera, possibly indicating partial melting, although the resolution is diminished at these depths. The distributed stations allow us to further complement body-wave tomography with ambient noise imaging and to obtain higher quality of Vs images. Our data processing includes single station data preparation and station-pair cross-correlation steps (Bensen et al., 2007), and the use of the phase weighted stacking method (Schimmel and Gallart, 2007) to improve the signal-to-noise ratio of the cross-correlations. We will show surface-wave dispersion curves, group velocity maps, and ultimately a 3D Vs image. By performing both body wave and ambient noise tomography, we provide a high

The preliminary results: Seismic ambient noise Rayleigh wave tomography around Merapi volcano, central Java, Indonesia

International Nuclear Information System (INIS)

Trichandi, Rahmantara; Yudistira, Tedi; Nugraha, Andri Dian; Zulhan, Zulfakriza; Saygin, Erdinc

2015-01-01

Ambient noise tomography is relatively a new method for imaging the shallow structure of the Earth subsurface. We presents the application of this method to produce a Rayleigh wave group velocity maps around the Merapi Volcano, Central Java. Rayleigh waves group velocity maps were reconstructed from the cross-correlation of ambient noise recorded by the DOMERAPI array which consists 43 broadband seismometers. In the processing stage, we first filtered the observation data to separatethe noise from the signal that dominated by the strong volcanic activities. Next, we cross-correlate the filtered data and stack to obtain the Green’s function for all possible station pairs. Then we carefully picked the peak of each Green’s function to estimate the dispersion trend and appliedMultiple Filter Technique to obtain the dispersion curve. Inter-station group velocity curvesare inverted to produceRayleigh wave group velocity maps for periods 1 to 10 s. The resulted Rayleigh group velocity maps show the interesting features around the Merapi Volcano which generally agree with the previous studies. Merapi-Lawu Anomaly (MLA) is emerged as a relatively low anomaly in our group velocity maps

The preliminary results: Seismic ambient noise Rayleigh wave tomography around Merapi volcano, central Java, Indonesia

Energy Technology Data Exchange (ETDEWEB)

Trichandi, Rahmantara, E-mail: rachmantara.tri@gmail.com [Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, 40132, Bandung (Indonesia); Yudistira, Tedi; Nugraha, Andri Dian [Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Zulhan, Zulfakriza [Earth Science Graduate Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Saygin, Erdinc [Research School of Earth Sciences, The Australian National University, Canberra ACT 0200 (Australia)

2015-04-24

Ambient noise tomography is relatively a new method for imaging the shallow structure of the Earth subsurface. We presents the application of this method to produce a Rayleigh wave group velocity maps around the Merapi Volcano, Central Java. Rayleigh waves group velocity maps were reconstructed from the cross-correlation of ambient noise recorded by the DOMERAPI array which consists 43 broadband seismometers. In the processing stage, we first filtered the observation data to separatethe noise from the signal that dominated by the strong volcanic activities. Next, we cross-correlate the filtered data and stack to obtain the Green’s function for all possible station pairs. Then we carefully picked the peak of each Green’s function to estimate the dispersion trend and appliedMultiple Filter Technique to obtain the dispersion curve. Inter-station group velocity curvesare inverted to produceRayleigh wave group velocity maps for periods 1 to 10 s. The resulted Rayleigh group velocity maps show the interesting features around the Merapi Volcano which generally agree with the previous studies. Merapi-Lawu Anomaly (MLA) is emerged as a relatively low anomaly in our group velocity maps.

Dynamic analysis of the Nova Target Chamber to assess alignment errors due to ambient noise

International Nuclear Information System (INIS)

McCallen, D.B.; Murray, R.C.

1984-01-01

We performed a study to determine the dynamic behavior of the Nova Target Chamber. We conducted a free vibration analysis to determine the natural frequencies of vibration and the corresponding modeshapes of the target chamber. Utilizing the free vibration results, we performed forced vibration analysis to predict the displacements of the chamber due to ambient vibration. The input support motion for the forced vibration analysis was defined by a white noise acceleration spectrum which was based on previous measurements of ground noise near the Nova site. A special purpose computer program was prepared to process the results of the forced vibration analysis. The program yields distances by which the lines of sight of the various laser beams miss the target as a result of ambient vibrations. We also performed additional estimates of miss distance to provide bounds on the results. A description of the finite element model of the chamber, the input spectrum, and the results of the analyses are included

Determination of Rayleigh wave ellipticity using single-station and array-based processing of ambient seismic noise

Science.gov (United States)

Workman, Eli Joseph

We present a single-station method for the determination of Rayleigh wave ellipticity, or Rayleigh wave horizontal to vertical amplitude ratio (H/V) using Frequency Dependent Polarization Analysis (FDPA). This procedure uses singular value decomposition of 3-by-3 spectral covariance matrices over 1-hr time windows to determine properties of the ambient seismic noise field such as particle motion and dominant wave-type. In FPDA, if the noise is mostly dominated by a primary singular value and the phase difference is roughly 90° between the major horizontal axis and the vertical axis of the corresponding singular vector, we infer that Rayleigh waves are dominant and measure an H/V ratio for that hour and frequency bin. We perform this analysis for all available data from the Earthscope Transportable Array between 2004 and 2014. We compare the observed Rayleigh wave H/V ratios with those previously measured by multicomponent, multistation noise cross-correlation (NCC), as well as classical noise spectrum H/V ratio analysis (NSHV). At 8 sec the results from all three methods agree, suggesting that the ambient seismic noise field is Rayleigh wave dominated. Between 10 and 30 sec, while the general pattern agrees well, the results from FDPA and NSHV are persistently slightly higher ( 2%) and significantly higher (>20%), respectively, than results from the array-based NCC. This is likely caused by contamination from other wave types (i.e., Love waves, body waves, and tilt noise) in the single station methods, but it could also reflect a small, persistent error in NCC. Additionally, we find that the single station method has difficulty retrieving robust Rayleigh wave H/V ratios within major sedimentary basins, such as the Williston Basin and Mississippi Embayment, where the noise field is likely dominated by reverberating Love waves.

Epicenter Location of Regional Seismic Events Using Love Wave and Rayleigh Wave Ambient Seismic Noise Green's Functions

Science.gov (United States)

Levshin, A. L.; Barmin, M. P.; Moschetti, M. P.; Mendoza, C.; Ritzwoller, M. H.

2011-12-01

We describe a novel method to locate regional seismic events based on exploiting Empirical Green's Functions (EGF) that are produced from ambient seismic noise. Elastic EGFs between pairs of seismic stations are determined by cross-correlating long time-series of ambient noise recorded at the two stations. The EGFs principally contain Rayleigh waves on the vertical-vertical cross-correlations and Love waves on the transverse-transverse cross-correlations. Earlier work (Barmin et al., "Epicentral location based on Rayleigh wave empirical Green's functions from ambient seismic noise", Geophys. J. Int., 2011) showed that group time delays observed on Rayleigh wave EGFs can be exploited to locate to within about 1 km moderate sized earthquakes using USArray Transportable Array (TA) stations. The principal advantage of the method is that the ambient noise EGFs are affected by lateral variations in structure similarly to the earthquake signals, so the location is largely unbiased by 3-D structure. However, locations based on Rayleigh waves alone may be biased by more than 1 km if the earthquake depth is unknown but lies between 2 km and 7 km. This presentation is motivated by the fact that group time delays for Love waves are much less affected by earthquake depth than Rayleigh waves; thus exploitation of Love wave EGFs may reduce location bias caused by uncertainty in event depth. The advantage of Love waves to locate seismic events, however, is mitigated by the fact that Love wave EGFs have a smaller SNR than Rayleigh waves. Here, we test the use of Love and Rayleigh wave EGFs between 5- and 15-sec period to locate seismic events based on the USArray TA in the western US. We focus on locating aftershocks of the 2008 M 6.0 Wells earthquake, mining blasts in Wyoming and Montana, and small earthquakes near Norman, OK and Dallas, TX, some of which may be triggered by hydrofracking or injection wells.

Linear Array Ambient Noise Adjoint Tomography Reveals Intense Crust-Mantle Interactions in North China Craton

Science.gov (United States)

Zhang, Chao; Yao, Huajian; Liu, Qinya; Zhang, Ping; Yuan, Yanhua O.; Feng, Jikun; Fang, Lihua

2018-01-01

We present a 2-D ambient noise adjoint tomography technique for a linear array with a significant reduction in computational cost and show its application to an array in North China. We first convert the observed data for 3-D media, i.e., surface-wave empirical Green's functions (EGFs) to the reconstructed EGFs (REGFs) for 2-D media using a 3-D/2-D transformation scheme. Different from the conventional steps of measuring phase dispersion, this technology refines 2-D shear wave speeds along the profile directly from REGFs. With an initial model based on traditional ambient noise tomography, adjoint tomography updates the model by minimizing the frequency-dependent Rayleigh wave traveltime delays between the REGFs and synthetic Green functions calculated by the spectral-element method. The multitaper traveltime difference measurement is applied in four-period bands: 20-35 s, 15-30 s, 10-20 s, and 6-15 s. The recovered model shows detailed crustal structures including pronounced low-velocity anomalies in the lower crust and a gradual crust-mantle transition zone beneath the northern Trans-North China Orogen, which suggest the possible intense thermo-chemical interactions between mantle-derived upwelling melts and the lower crust, probably associated with the magmatic underplating during the Mesozoic to Cenozoic evolution of this region. To our knowledge, it is the first time that ambient noise adjoint tomography is implemented for a 2-D medium. Compared with the intensive computational cost and storage requirement of 3-D adjoint tomography, this method offers a computationally efficient and inexpensive alternative to imaging fine-scale crustal structures beneath linear arrays.

Association between ambient noise exposure and school performance of children living in an urban area: a cross-sectional population-based study.

Science.gov (United States)

Pujol, Sophie; Levain, Jean-Pierre; Houot, Hélène; Petit, Rémy; Berthillier, Marc; Defrance, Jérôme; Lardies, Joseph; Masselot, Cyril; Mauny, Frédéric

2014-04-01

Most of the studies investigating the effects of the external noise on children's school performance have concerned pupils in schools exposed to high levels due to aircraft or freeway traffic noise. However, little is known about the consequences of the chronic ambient noise exposure at a level commonly encountered in residential urban areas. This study aimed to assess the relationship between the school performance of 8- to 9-year-old-children living in an urban environment and their chronic ambient noise exposure at home and at school. The children's school performances on the national standardized assessment test in French and mathematics were compared with the environmental noise levels. Children's exposure to ambient noise was calculated in front of their bedrooms (Lden) and schools (LAeq,day) using noise prediction modeling. Questionnaires were distributed to the families to collect potential confounding factors. Among the 746 respondent children, 586 were included in multilevel analyses. On average, the LAeq,day at school was 51.5 dB (SD= 4.5 dB; range = 38-58 dB) and the outdoor Lden at home was 56.4 dB (SD= 4.4 dB; range = 44-69 dB). LAeq,day at school was associated with impaired mathematics score (p = 0.02) or impaired French score (p = 0.01). For a + 10 dB gap, the French and mathematics scores were on average lower by about 5.5 points. Lden at home was significantly associated with impaired French performance when considered alone (p school exposure was considered (p = 0.06). The magnitude of the observed effect on school performance may appear modest, but should be considered in light of the number of people who are potentially chronically exposed to similar environmental noise levels.

A 380pW Dual Mode Optical Wake-up Receiver with Ambient Noise Cancellation.

Science.gov (United States)

Lim, Wootaek; Jang, Taekwang; Lee, Inhee; Kim, Hun-Seok; Sylvester, Dennis; Blaauw, David

2016-06-01

We present a sub-nW optical wake-up receiver for wireless sensor nodes. The wake-up receiver supports dual mode operation for both ultra-low standby power and high data rates, while canceling ambient in-band noise. In 0.18µm CMOS the receiver consumes 380pW in always-on wake-up mode and 28.1µW in fast RX mode at 250kbps.

3D Crust and Uppermost Mantle Structure beneath Tian Shan Region from ambient noise and earthquake surface waves

Science.gov (United States)

Xiao, X.; Wen, L.

2017-12-01

As a typical active intracontinental mountain range in Central Asia, Tian Shan Mt serves as the prototype in studying geodynamic processes and mechanism of intracontinental mountain building. We study 3D crust and the uppermost mantle structure beneath Tian Shan region using ambient noise and earthquake surface waves. Our dataset includes vertical component records of 62 permanent broadband seismic stations operated by the Earthquake Administration of China. Firstly, we calculate two-year stacked Cross-Correlation Functions (CCFs) of ambient noise records between the stations. The CCFs are treated as the Empirical Green's Functions (EGFs) of each station pair, from which we measured phase velocities of fundamental-mode Rayleigh wave in the period of 3-40 s using a frequency-time analysis method. Secondly, we collect surface wave data from tele-seismic events with Mw > 5.5 and depth shallower than 200 km and measure phase velocities of the fundamental-mode of Rayleigh wave in the period of 30-150 s using a two-station method. Finally, we combine the phase velocity measurements from ambient noise and earthquake surface waves, obtain lateral isotropic phase velocity maps at different periods based on tomography and invert a 3D Vsv model of crust and uppermost mantle down to about 150 km using a Monte Carlo Inversion method. We will discuss our inversion results in detail, as well as their implications to the tectonics in the region.

Significance of geological units of the Bohemian Massif, Czech Republic, as seen by ambient noise interferometry

Czech Academy of Sciences Publication Activity Database

Růžek, Bohuslav; Valentová, L.; Gallovič, F.

2016-01-01

Roč. 173, č. 5 (2016), s. 1663-1682 ISSN 0033-4553 R&D Projects: GA ČR GAP210/12/2336; GA MŠk LM2010008 Institutional support: RVO:67985530 Keywords : ambient noise * geological units * Bohemian Massif * velocity model Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.591, year: 2016

Statistics and vertical directionality of low-frequency ambient noise at the North Pacific Acoustics Laboratory site

Science.gov (United States)

Baggeroer, Arthur B.; NPAL Group; Colosi, J. A.; Cornuelle, B. D.; Dushaw, B. D.; Dzieciuch, M. A.; Howe, B. M.; Mercer, J. A.; Munk, W. H.; Spindel, R. C.; Worcester, P. F.

2005-03-01

We examine statistical and directional properties of the ambient noise in the 10-100 Hz frequency band from the NPAL array. Marginal probability densities are estimated as well as mean square levels, skewness and kurtoses in third octave bands. The kurotoses are markedly different from Gaussian except when only distant shipping is present. Extremal levels reached ~150 dB re 1 μ Pa, suggesting levels 60dB greater than the mean ambient were common in the NPAL data sets. Generally, these were passing ships. We select four examples: i) quiescent noise, ii) nearby shipping, iii) whale vocalizations and iv) a micro earthquake for the vertical directional properties of the NPAL noise since they are representative of the phenomena encountered. We find there is modest broadband coherence for most of these cases in their occupancy band across the NPAL aperture. Narrowband coherence analysis from VLA to VLA was not successful due to ambiguities. Examples of localizing sources based upon this coherence are included. kw diagrams allow us to use data above the vertical aliasing frequency. Ducted propagation for both the quiescent and micro earthquake (T phase) are identified and the arrival angles of nearby shipping and whale vocalizations. MFP localizations were modestly successful for nearby sources, but long range ones could not be identified, most likely because of signal mismatch in the MFP replica. .

Characteristics of Love and Rayleigh waves in ambient noise: wavetype ratio, source location and seasonal behavior

Science.gov (United States)

Juretzek, C.; Perleth, M.; Hadziioannou, C.

2015-12-01

Ambient seismic noise has become an important source of signal for tomography and monitoring purposes. Better understanding of the noise field characteristics is crucial to further improve noise applications. Our knowledge about the common and different origins of Love and Rayleigh waves in the microseism bands is still limited. This applies in particular to constraints on source locations and source mechanisms of Love waves. Here, 3-component beamforming is used to distinguish between the differently polarized wave types present in the noise field recorded at several arrays across Europe. The focus lies on frequencies around the primary and secondary microseismic bands. We compare characteristics of Love and Rayleigh wave noise, such as source directions and frequency content. Further, Love to Rayleigh wave ratios are measured at each array, and a dependence on direction is observed. We constrain the corresponding source regions of both wave types by backprojection. By using a full year of data in 2013, we are able to track the seasonal changes in our observations of Love-to-Rayleigh ratio and source locations.

Ambient Sensors

NARCIS (Netherlands)

Börner, Dirk; Specht, Marcus

2014-01-01

This software sketches comprise two custom-built ambient sensors, i.e. a noise and a movement sensor. Both sensors measure an ambient value and process the values to a color gradient (green > yellow > red). The sensors were built using the Processing 1.5.1 development environment. Available under

Characterization of site-effects in the urban area of Canakkale, Turkey, using ambient noise measurements

Science.gov (United States)

Demirci, Alper; Bekler, Tolga; Karagöz, Özlem

2010-05-01

The local site conditions can cause variations in the ground motion during the earthquake events. These local effects can be estimated by Nakamura method (1989) which is based on the analysis and treatment of earth vibration records by calculating the ratio of horizontal spectrum to vertical spectrum (H/V). This approach uses ambient noises and aids to estimate the dynamic soil conditions like fundamental vibration period and soil amplification of the surface layers, to characterize the seismic hazard during earthquakes and to provide detailed information for seismic microzonation in small scale urban areas. Due to these advantages, the method has been frequently used by a great number of seismologists and engineers. In this study, we aimed at explaining the soil conditions in Çanakkale and Kepez basins by using H/V technique. Çanakkale and Kepez (NW, Turkey) have fairly complex tectonic structure and have been exposed to serious earthquake damages in historical and instrumental period. Active faults, which have influence on the Çanakkale and Kepez settlements, are the Yenice-Gönen fault, Saroz-Gaziköy fault and Etili fault. It is well known that, these faults have produced high magnitude earthquakes such as 7.2 in 1912 and 7.3 in 1953. The surface geology of the surveyed area is covered by quaternary aged sediments. Sarıçay river, which originates from the eastern hilly area, accumulates sediment deposits and forms this alluvial basin. Considering the geological conditions, ambient noises were recorded at 88 measurement points which were selected to provide good coverage of the study area. All records were acquired during the midnight (between 1:00 am and 6:00 am) to reduce the artificial effects in the urban area. Taking into account the effects of undesirable traffic and industrial noises in the vicinity of measurements stations, record lengths were chosen in the range of 25-75 minutes with the sampling rate of 100 Hz. Once the required signal processes

Ambient Noise Tomography in Koyna-Warna region.

Science.gov (United States)

Rohilla, S.; Rao, N. P.; Gerstoft, P.; Yao, H.; Fang, H.; Davulluri, S.

2017-12-01

In the present study Ambient Noise tomography has been done in the Koyna-Warna region of western India to decipher the complex structural setting and its linkage to the seismogenesis in this unique Reservoir Triggered Seismicity zone. The 3-D velocity model obtained from the study clearly brings out the lateral and vertical variations of shear velocity in the region down to a depth of about 10 km. In the Koyna region, seismicity distribution along the NNE-SSW trending Donachiwada fault zone is seen coinciding with a low velocity zone between two competent zones with a very high velocity > 4.0 km/s. The seismicity between the Koyna and Warna regions roughly trending NW-SE can be clearly seen in the NE-SW depth sections coinciding with a low velocity zone interspersed between two high velocity zones. The most active seismicity cluster south of the Warna Lake correlates with a near-vertical velocity discontinuity with a contrast of about 0.5 km/s is seen in an EW depth section. The study has helped in delineating the major fault zones of the Koyna-Warna region and enabled understanding the seismogenesis with respect to the structural controls in a RTS enviroment.

APL-UW Deep Water Propagation: Philippine Sea Signal Physics and North Pacific Ambient Noise and NPANL Support

Science.gov (United States)

2014-09-30

involve us in workshops focusing on the impact of ambient noise on the acoustic marine soundscape , and and invite DOS Kauai Linux CPU 294± ≈ 15 286... SoundScapes ” and a planning letter titled “GLOSS: GLobal Ocean SoundScapes : Phase I Connecting the worlds oceans through sound” have been produced in order

Reducing Risk of Noise-Induced Hearing Loss in Collegiate Music Ensembles Using Ambient Technology.

Science.gov (United States)

Powell, Jason; Chesky, Kris

2017-09-01

Student musicians are at risk for noise-induced hearing loss (NIHL) as they develop skills and perform during instructional activities. Studies using longitudinal dosimeter data show that pedagogical procedures and instructor behaviors are highly predictive of NIHL risk, thus implying the need for innovative approaches to increase instructor competency in managing instructional activities without interfering with artistic and academic freedom. Ambient information systems, an emerging trend in human-computer interaction that infuses psychological behavioral theories into technologies, can help construct informative risk-regulating systems. The purpose of this study was to determine the effects of introducing an ambient information system into the ensemble setting. The system used two ambient displays and a counterbalanced within-subjects treatment study design with six jazz ensemble instructors to determine if the system could induce a behavior change that alters trends in measures resulting from dosimeter data. This study assessed efficacy using time series analysis to determine changes in eight statistical measures of behavior over a 9-wk period. Analysis showed that the system was effective, as all instructors showed changes in a combination of measures. This study is in an important step in developing non-interfering technology to reduce NIHL among academic musicians.

Seismic structure of the upper crust in the Albertine Rift from travel-time and ambient-noise tomography - a comparison

Science.gov (United States)

Jakovlev, Andrey; Kaviani, Ayoub; Ruempker, Georg

2017-04-01

Here we present results of the investigation of the upper crust in the Albertine rift around the Rwenzori Mountains. We use a data set collected from a temporary network of 33 broadband stations operated by the RiftLink research group between September 2009 and August 2011. During this period, 82639 P-wave and 73408 S-wave travel times from 12419 local and regional earthquakes were registered. This presents a very rare opportunity to apply both local travel-time and ambient-noise tomography to analyze data from the same network. For the local travel-time tomographic inversion the LOTOS algorithm (Koulakov, 2009) was used. The algorithm performs iterative simultaneous inversions for 3D models of P- and S-velocity anomalies in combination with earthquake locations and origin times. 28955 P- and S-wave picks from 2769 local earthquakes were used. To estimate the resolution and stability of the results a number of the synthetic and real data tests were performed. To perform the ambient noise tomography we use the following procedure. First, we follow the standard procedure described by Bensen et al. (2007) as modified by Boué et al. (2014) to compute the vertical component cross-correlation functions between all pairs of stations. We also adapted the algorithm introduced by Boué et al. (2014) and use the WHISPER software package (Briand et al., 2013) to preprocess individual daily vertical-component waveforms. On the next step, for each period, we use the method of Barmin et al. (2001) to invert the dispersion measurements along each path for group velocity tomographic maps. Finally, we adapt a modified version of the algorithm suggested by Macquet et al. (2014) to invert the group velocity maps for shear velocity structure. We apply several tests, which show that the best resolution is obtained at a period of 8 seconds, which correspond to a depth of approximately 6 km. Models of the seismic structure obtained by the two methods agree well at shallow depth of about

Total annoyance from an industrial noise source with a main spectral component combined with a background noise.

Science.gov (United States)

Alayrac, M; Marquis-Favre, C; Viollon, S

2011-07-01

When living close to an industrial plant, people are exposed to a combination of industrial noise sources and a background noise composed of all the other noise sources in the environment. As a first step, noise annoyance indicators in laboratory conditions are proposed for a single exposure to an industrial noise source. The second step detailed in this paper involves determining total annoyance indicators in laboratory conditions for ambient noises composed of an industrial noise source and a background noise. Two types of steady and permanent industrial noise sources are studied: low frequency noises with a main spectral component at 100 Hz, and noises with a main spectral component in middle frequencies. Five background noises are assessed so as to take into account different sound environments which can usually be heard by people living around an industrial plant. One main conclusion of this study is that two different analyses are necessary to determine total annoyance indicators for this type of ambient noise, depending on the industrial noise source composing it. Therefore, two total annoyance indicators adapted to the ambient noises studied are proposed. © 2011 Acoustical Society of America

Full-Wave Ambient Noise Tomography of the Long Valley Volcanic Region (California)

Science.gov (United States)

Flinders, A. F.; Shelly, D. R.; Dawson, P. B.; Hill, D. P.; Shen, Y.

2017-12-01

In the late 1970s, and throughout the 1990s, Long Valley Caldera (California) experienced intense periods of unrest characterized by uplift of the resurgent dome, earthquake swarms, and CO2 emissions around Mammoth Mountain. While modeling of the uplift and gravity changes support the possibility of new magmatic intrusions beneath the caldera, geologic interpretations conclude that the magmatic system underlying the caldera is moribund. Geophysical studies yield diverse versions of a sizable but poorly resolved low-velocity zone at depth (> 6km), yet whether this zone is indicative of a significant volume of crystal mush, smaller isolated pockets of partial melt, or magmatic fluids, is inconclusive. The nature of this low-velocity zone, and the state of volcano's magmatic system, carry important implications for the significance of resurgent-dome inflation and the nature of associated hazards. To better characterize this low-velocity zone we present preliminary results from a 3D full-waveform ambient-noise seismic tomography model derived from the past 25 years of vertical component broadband and short-period seismic data. This new study uses fully numerical solutions of the wave equation to account for the complex wave propagation in a heterogeneous, 3D earth model, including wave interaction with topography. The method ensures that wave propagation is modeled accurately in 3D, enabling the full use of seismic records. By using empirical Green's functions, derived from ambient noise and modeled as Rayleigh surface waves, we are able to extend model resolution to depths beyond the limits of previous local earthquake studies. The model encompasses not only the Long Valley Caldera, but the entire Long Valley Volcanic Region, including Mammoth Mountain and the Mono Crater/Inyo Domes volcanic chain.

Noise from wind turbines

Energy Technology Data Exchange (ETDEWEB)

Fegeant, Olivier [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Building Sciences

2002-02-01

A rapid growth of installed wind power capacity is expected in the next few years. However, the siting of wind turbines on a large scale raises concerns about their environmental impact, notably with respect to noise. To this end, variable speed wind turbines offer a promising solution for applications in densely populated areas like the European countries, as this design would enable an efficient utilisation of the masking effect due to ambient noise. In rural and recreational areas where wind turbines are sited, the ambient noise originates from the action of wind on the vegetation and about the listener's ear (pseudo-noise). It shows a wind speed dependence similar to that of the noise from a variable speed wind turbine and can therefore mask the latter for a wide range of conditions. However, a problem inherent to the design of these machines is their proclivity to pure tone generation, because of the enhanced difficulty of avoiding structural resonances in the mechanical parts. Pure tones are deemed highly annoying and are severely regulated by most noise policies. In relation to this problem, the vibration transmission of structure-borne sound to the tower of the turbine is investigated, in particular when the tower is stiffened at its upper end. Furthermore, since noise annoyance due to wind turbine is mostly a masking issue, the wind-related sources of ambient noise are studied and their masking potentials assessed. With this aim, prediction models for wind-induced vegetation noise and pseudo-noise have been developed. Finally, closely related to the effect of masking, is the difficulty, regularly encountered by local authorities and wind farm developers, to measure noise immission from wind turbines. A new measurement technique has thus been developed in the course of this work. Through improving the signal-to-noise ratio between wind turbine noise and ambient noise, the new technique yields more accurate measurement results.

Rayleigh wave tomography of the British Isles from ambient seismic noise

Science.gov (United States)

Nicolson, Heather; Curtis, Andrew; Baptie, Brian

2014-08-01

We present the first Rayleigh wave group speed maps of the British Isles constructed from ambient seismic noise. The maps also constitute the first surface wave tomography study of the crust under the British Isles at a relatively high resolution. We computed interferometric, interstation Rayleigh waves from vertical component records of ambient seismic noise recorded on 63 broad-band and short-period stations across the UK and Ireland. Group velocity measurements were made from the resulting surface wave dispersion curves between 5 and 25 s using a multiple phase-matched filter method. Uncertainties in the group velocities were computed by calculating the standard deviation of four dispersion curves constructed by stacking a random selection of daily cross-correlations. Where an uncertainty could not be obtained for a ray path using this method, we estimated it as a function of the interreceiver distance. Group velocity maps were computed for 5-25-s period using the Fast Marching forward solution of the eikonal equation and iterative, linearized inversion. At short and intermediate periods, the maps show remarkable agreement with the major geological features of the British Isles including: terrane boundaries in Scotland; regions of late Palaeozoic basement uplift; areas of exposed late Proterozoic/early Palaeozoic rocks in southwest Scotland, northern England and northwest Wales and, sedimentary basins formed during the Mesozoic such as the Irish Sea Basin, the Chester Basin, the Worcester Graben and the Wessex Basin. The maps also show a consistent low-velocity anomaly in the region of the Midlands Platform, a Proterozoic crustal block in the English Midlands. At longer periods, which are sensitive velocities in the lower crustal/upper mantle, the maps suggest that the depth of Moho beneath the British Isles decreases towards the north and west. Areas of fast velocity in the lower crust also coincide with areas thought to be associated with underplating of the

Assimilation of ambient seismic noise in hydrological models allows estimation of hydraulic conductivity in unsaturated media

Science.gov (United States)

Fores, B.; Champollion, C.; Mainsant, G.; Fort, A.; Albaric, J.

2016-12-01

Karstic hydrosystems represent one of the main water resources in the Mediterranean area but are challenging for geophysical methods. The GEK (Geodesy in Karstic Environment) observatory has been setup in 2011 to study the unsaturated zone of a karstic system in the south of France. The unsaturated zone (the epikarst) is thick and up to 100m on the site. Since 2011, gravity, rainfall and evapotranspiration are monitored. Together, they allow precise estimation of the global water storage changes but lack depth resolution. Surface waves velocity variations, obtained from ambient seismic noise monitoring are used here to overcome this lack. Indeed, velocities depend on saturation and the depths where changes occur can be defined as surface waves are dispersive. From October 2014 to November 2015, two seismometers have been recording noise. Velocity changes at a narrow frequency band (6-8 Hz) have shown a clear annual cycle. Minimum velocity is several months late on precipitations, which is coherent with a slow infiltration and a maximum sensitivity at -40m for these frequencies and this site. Models have been made with the Hydrus-1D software which allows modeling 1D-flow in variably saturated media. With a stochastic sampling, we have researched the underground parameters that reproduce the most the different observations (gravity, evapotranspiration and rainfall, and velocity changes). We show that velocity changes clearly constrain the hydraulic conductivity of the medium. Ambient seismic noise is therefore a promising method to study unsaturated zone which are too deep or too heterogeneous for classic methods.

Classroom Noise and Teachers' Voice Production

Science.gov (United States)

Rantala, Leena M.; Hakala, Suvi; Holmqvist, Sofia; Sala, Eeva

2015-01-01

Purpose: The aim of this study was to research the associations between noise (ambient and activity noise) and objective metrics of teachers' voices in real working environments (i.e., classrooms). Method: Thirty-two female and 8 male teachers from 14 elementary schools were randomly selected for the study. Ambient noise was measured during breaks…

Correlações entre ruído ambiental em sala de aula e voz do professor Correlations between classroom environmental noise and teachers' voice

Directory of Open Access Journals (Sweden)

Rafaela Fernanda Guidini

2012-12-01

Full Text Available OBJETIVO: Identificar se existe correlação entre ruído ambiental no interior da sala de aula, intensidade da voz e presença de alteração vocal em professores. MÉTODOS: Foi realizada medição do ruído ambiental em dez salas de escolas municipais de ensino fundamental. A intensidade das vozes das professoras foi medida durante atividade de ensino. Amostras de vogal prolongada [é] e contagem de 1 a 20 emitidas pelas professoras foram analisadas utilizando escala GRBASI. Os resultados obtidos foram correlacionados. RESULTADOS: A média de ruído ambiental sem a presença das crianças em sala de aula variou de 40 a 51 dB(A e com a presença das crianças de 45 a 65 dB(A. Entre as professoras, houve 70% de ocorrência de vozes alteradas no grau geral (G e 90% com tensão na voz (S, variando entre graus discreto e moderado. Constatou-se variação entre 52 dB(A e 68 dB(A na intensidade da voz das professoras, atingindo 7,48 dB(A acima do nível do ruído ambiental. Houve correlação entre a intensidade vocal das professoras e ruído ambiental na presença das crianças durante a aula. CONCLUSÃO: Os níveis de ruído ambiental em sala de aula são altos e se correlacionam com o aumento da intensidade das vozes das professoras. Embora com alta ocorrência de vozes alteradas, não é possível correlacioná-las com o nível de ruído ambiental.PURPOSE: To explore the existence of correlations between environmental noise in classrooms, voice intensity and teacher's vocal problems. METHODS: Environmental noise was measured in 10 classrooms of municipal elementary schools; the intensity of teachers' voice was measured during teaching practice; teachers' speech samples containing emissions of sustained vowel [é] and counting from 1 to 20 were analyzed using the GRBASI protocol; and the results were tested for correlation. RESULTS: The average of environmental noise varied from 40 to 51 dB(A without the presence of children in the classroom, and

Reorganization of auditory map and pitch discrimination in adult rats chronically exposed to low-level ambient noise

Directory of Open Access Journals (Sweden)

Weimin eZheng

2012-09-01

Full Text Available Behavioral adaption to a changing environment is critical for an animal’s survival. How well the brain can modify its functional properties based on experience essentially defines the limits of behavioral adaptation. In adult animals the extent to which experience shapes brain function has not been fully explored. Moreover, the perceptual consequences of experience-induced changes in the brains of adults remain unknown. Here we show that the tonotopic map in the primary auditory cortex of adult rats living with low-level ambient noise underwent a dramatic reorganization. Behaviorally, chronic noise-exposure impaired fine, but not coarse pitch discrimination. When tested in a noisy environment, the noise-exposed rats performed as well as in a quiet environment whereas the control rats performed poorly. This suggests that noise-exposed animals had adapted to living in a noisy environment. Behavioral pattern analyses revealed that stress or distraction engendered by the noisy background could not account for the poor performance of the control rats in a noisy environment. A reorganized auditory map may therefore have served as the neural substrate for the consistent performance of the noise-exposed rats in a noisy environment.

Rayleigh wave group-velocity across the Dominican Republic and Puerto Rico from ambient noise tomography

Science.gov (United States)

Quiros, D.; Pulliam, J.; Polanco Rivera, E.; Huerfano Moreno, V. A.

2017-12-01

The eastern North America-Caribbean (NA-CAR) plate boundary near the islands of Hispaniola (which is comprised of the Dominican Republic and Haiti) and Puerto Rico is a complex transition zone in which strain is accommodated by two transform fault systems and oblique subduction. In 2013, scientists from Baylor University, the Autonomous University of Santo Domingo, and the Puerto Rico Seismic Network deployed 16 broadband stations on the Dominican Republic to expand the local permanent network. The goal of the Greater Antilles Seismic Program (GrASP) is to combine its data with that from permanent networks in Puerto Rico, Haiti, Cuba, the Cayman Islands, and Jamaica to develop a better understanding of the crust and upper mantle structure in the Northeastern Caribbean (Greater Antilles). One important goal of GrASP is to develop robust velocity models that can be used to improve earthquake location and seismic hazard efforts. In this study, we focus on obtaining Rayleigh wave group velocity maps from ambient noise tomography. By cross-correlating ambient seismic noise recorded at 53 stations between 2010 to present, we obtain Green's functions between 1165 pairs of stations. From these, we obtain dispersion curves by the application of FTAN methods with phase-matched filtering. Selection criteria depend on the signal-to-noise ratio and seasonal variability, with further filtering done by rejecting velocities incompatible with maps produced from overdamped tomographic inversions. Preliminary dispersion maps show strong correlations with large-scale geological and tectonic features for periods between 5 - 20 s, such as the Cordillera Central in both the Dominican Republic and Puerto Rico, the Mona Passage, and the NA-CAR subduction zone. Ongoing efforts focus on including shorter periods in Puerto Rico as its denser station distribution could allow us to retrieve higher resolution group velocity maps.

Environmental resources of selected areas of Hawaii: Climate, ambient air quality, and noise

Energy Technology Data Exchange (ETDEWEB)

Lombardi, D.A.; Blasing, T.J.; Easterly, C.E.; Reed, R.M. [Oak Ridge National Lab., TN (United States); Hamilton, C.B. [Univ. of Tennessee, Knoxville, TN (United States)

1995-03-01

This report has been prepared to make available and archive background scientific data and related information on climate, ambient air quality, and ambient noise levels collected during the preparation of the environmental impact statement (EIS) for Phases 3 and 4 of the Hawaii Geothermal Project (HGP) as defined by the state of Hawaii in its April 1989 proposal to Congress. The US Department of Energy (DOE) published a notice withdrawing its Notice of Intent to prepare the HGP-EIS. Since the state of Hawaii is no longer pursuing or planning to pursue the HGP, DOE considers the project to be terminated. The report presents a general description of the climate add air quality for the islands of Hawaii (henceforth referred to as Hawaii), Maui and Oahu. It also presents a literature review as baseline information on the health effects of sulfide. The scientific background data and related information is being made available for use by others in conducting future scientific research in these areas. This report describes the environmental resources present in the areas studied (i.e., the affected environment) and does not represent an assessment of environmental impacts.

Ambient seismic noise levels: A survey of the permanent and temporary seismographic networks in Morocco, North Africa

Science.gov (United States)

El Fellah, Y.; Khairy Abd Ed-Aal, A.; El Moudnib, L.; Mimoun, H.; Villasenor, A.; Gallart, J.; Thomas, C.; Elouai, D.; Mimoun, C.; Himmi, M.

2013-12-01

Abstract The results, of a conducted study carried out to analyze variations in ambient seismic noise levels at sites of the installed broadband stations in Morocco, North Africa, are obtained. The permanent and the temporary seismic stations installed in Morocco of the Scientific Institute ( IS, Rabat, Morocco), institute de Ciencias de la Tierra Jaume almera (ICTJA, Barcelona, Spain) and Institut für Geophysik (Munster, Germany) were used in this study. In this work, we used 23 broadband seismic stations installed in different structural domains covering all Morocco from south to north. The main purposes of the current study are: 1) to present a catalog of seismic background noise spectra for Morocco obtained from recently installed broadband stations, 2) to assess the effects of experimental temporary seismic vault construction, 3) to determine the time needed for noise at sites to stabilize, 4) to establish characteristics and origin of seismic noise at those sites. We calculated power spectral densities of background noise for each component of each broadband seismometer deployed in the different investigated sites and then compared them with the high-noise model and low-noise Model of Peterson (1993). All segments from day and night local time windows were included in the calculation without parsing out earthquakes. The obtained results of the current study could be used forthcoming to evaluate permanent station quality. Moreover, this study could be considered as a first step to develop new seismic noise models in North Africa not included in Peterson (1993). Keywords Background noise; Power spectral density; Model of Peterson; Scientific Institute; Institute de Ciencias de la Tierra Jaume almera; Institut für Geophysik

Ambient noise tomography across Mount St. Helens using a dense seismic array

KAUST Repository

Wang, Yadong

2017-05-08

We investigated upper crustal structure with data from a dense seismic array deployed around Mount St. Helens for 2 weeks in the summer of 2014. Interstation cross correlations of ambient seismic noise data from the array were obtained, and clear fundamental mode Rayleigh waves were observed between 2.5 and 5 s periods. In addition, higher-mode signals were observed around 2 s period. Frequency-time analysis was applied to measure fundamental mode Rayleigh wave phase velocities, which were used to invert for 2-D phase velocity maps. An azimuth-dependent traveltime correction was implemented to mitigate potential biases introduced due to an inhomogeneous noise source distribution. Reliable phase velocity maps were only obtained between 3 and 4 s periods due to limitations imposed by the array aperture and higher-mode contamination. The phase velocity tomography results, which are sensitive to structure shallower than 6 km depth, reveal an ~10–15% low-velocity anomaly centered beneath the volcanic edifice and peripheral high-velocity anomalies that likely correspond to cooled igneous intrusions. We suggest that the low-velocity anomaly reflects the high-porosity mixture of lava and ash deposits near the surface of the edifice, a highly fractured magmatic conduit and hydrothermal system beneath the volcano, and possibly a small contribution from silicate melt.

Measuring changes in ambient noise levels from the installation and operation of a surge wave energy converter in the coastal ocean

Energy Technology Data Exchange (ETDEWEB)

Haxel, Joe H [Oregon State Univ., Newport, OR (United States); Henkel, Sarah K [Oregon State Univ., Newport, OR (United States)

2017-10-18

Ecosystem impacts resulting from elevated underwater noise levels generated by anthropogenic activities in the coastal ocean are poorly understood and remain difficult to address as a result of a significant gap in knowledge for existing nearshore sound levels. Ambient noise is an important habitat component for marine mammals and fish that use sound for essential functions such as communication, navigation, and foraging. Questions surrounding the amplitudes, frequency distributions, and durations of noise emissions from renewable wave energy conversion (WEC) projects during their construction and operation present concerns for long-term consequences in marine habitats. Oregon’s dynamic nearshore environment presents significant challenges for passive acoustic monitoring that include flow noise contamination from wave orbital motions, turbulence from breaking surf, equipment burial, and fishing pressure from sport and commercial crabbers. This project included 2 techniques for passive acoustic data collection: 1) campaign style deployments of fixed hydrophone lander stations to capture temporal variations in noise levels and 2) a drifting hydrophone system to record spatial variations within the project site. The hydrophone lander deployments were effective and economically feasible for enabling robust temporal measurements of ambient noise levels in a variety of sea state conditions. Limiting factors for the fixed stations included 1) a flow shield mitigation strategy failure in the first deployment resulting in significant wideband data contamination and 2) flow noise contamination of the unshielded sensors restricting valuable analysis to frequencies above 500 Hz for subsequent deployments. Drifting hydrophone measurements were also effective and economically feasible (although logistically challenging in the beginning of the project due to vessel time constraints) providing a spatial distribution of sound levels, comparisons of noise levels in varying levels

Integration of ambient seismic noise monitoring, displacement and meteorological measurements to infer the temperature-controlled long-term evolution of a complex prone-to-fall cliff

Science.gov (United States)

Colombero, C.; Baillet, L.; Comina, C.; Jongmans, D.; Larose, E.; Valentin, J.; Vinciguerra, S.

2018-06-01

Monitoring the temporal evolution of resonance frequencies and velocity changes detected from ambient seismic noise recordings can help in recognizing reversible and irreversible modifications within unstable rock volumes. With this aim, the long-term ambient seismic noise data set acquired at the potentially unstable cliff of Madonna delSasso (NW Italian Alps) was analysed in this study, using both spectral analysis and cross-correlation techniques. Noise results were integrated and compared with direct displacement measurements and meteorological data, to understand the long-term evolution of the cliff. No irreversible modifications in the stability of the site were detected over the monitored period. Conversely, daily and seasonal air temperature fluctuations were found to control resonance frequency values, amplitudes and directivities and to induce reversible velocity changes within the fractured rock mass. The immediate modification in the noise parameters due to temperature fluctuations was interpreted as the result of rock mass thermal expansion and contraction, inducing variations in the contact stiffness along the fractures isolating two unstable compartments. Differences with previous case studies were highlighted in the long-term evolution of noise spectral amplitudes and directivities, due to the complex 3-D fracture setting of the site and to the combined effects of the two unstable compartments.

Long-term exposure to road traffic noise, ambient air pollution, and cardiovascular risk factors in the HUNT and lifelines cohorts.

Science.gov (United States)

Cai, Yutong; Hansell, Anna L; Blangiardo, Marta; Burton, Paul R; de Hoogh, Kees; Doiron, Dany; Fortier, Isabel; Gulliver, John; Hveem, Kristian; Mbatchou, Stéphane; Morley, David W; Stolk, Ronald P; Zijlema, Wilma L; Elliott, Paul; Hodgson, Susan

2017-08-01

Blood biochemistry may provide information on associations between road traffic noise, air pollution, and cardiovascular disease risk. We evaluated this in two large European cohorts (HUNT3, Lifelines). Road traffic noise exposure was modelled for 2009 using a simplified version of the Common Noise Assessment Methods in Europe (CNOSSOS-EU). Annual ambient air pollution (PM10, NO2) at residence was estimated for 2007 using a Land Use Regression model. The statistical platform DataSHIELD was used to pool data from 144 082 participants aged ≥20 years to enable individual-level analysis. Generalized linear models were fitted to assess cross-sectional associations between pollutants and high-sensitivity C-reactive protein (hsCRP), blood lipids and for (Lifelines only) fasting blood glucose, for samples taken during recruitment in 2006-2013. Pooling both cohorts, an inter-quartile range (IQR) higher day-time noise (5.1 dB(A)) was associated with 1.1% [95% confidence interval (95% CI: 0.02-2.2%)] higher hsCRP, 0.7% (95% CI: 0.3-1.1%) higher triglycerides, and 0.5% (95% CI: 0.3-0.7%) higher high-density lipoprotein (HDL); only the association with HDL was robust to adjustment for air pollution. An IQR higher PM10 (2.0 µg/m3) or NO2 (7.4 µg/m3) was associated with higher triglycerides (1.9%, 95% CI: 1.5-2.4% and 2.2%, 95% CI: 1.6-2.7%), independent of adjustment for noise. Additionally for NO2, a significant association with hsCRP (1.9%, 95% CI: 0.5-3.3%) was seen. In Lifelines, an IQR higher noise (4.2 dB(A)) and PM10 (2.4 µg/m3) was associated with 0.2% (95% CI: 0.1-0.3%) and 0.6% (95% CI: 0.4-0.7%) higher fasting glucose respectively, with both remaining robust to adjustment for air/noise pollution. Long-term exposures to road traffic noise and ambient air pollution were associated with blood biochemistry, providing a possible link between road traffic noise/air pollution and cardio-metabolic disease risk. Published on behalf of the European Society of

Accurate Ambient Noise Assessment Using Smartphones

Science.gov (United States)

Zamora, Willian; Calafate, Carlos T.; Cano, Juan-Carlos; Manzoni, Pietro

2017-01-01

Nowadays, smartphones have become ubiquitous and one of the main communication resources for human beings. Their widespread adoption was due to the huge technological progress and to the development of multiple useful applications. Their characteristics have also experienced a substantial improvement as they now integrate multiple sensors able to convert the smartphone into a flexible and multi-purpose sensing unit. The combined use of multiple smartphones endowed with several types of sensors gives the possibility to monitor a certain area with fine spatial and temporal granularity, a procedure typically known as crowdsensing. In this paper, we propose using smartphones as environmental noise-sensing units. For this purpose, we focus our study on the sound capture and processing procedure, analyzing the impact of different noise calculation algorithms, as well as in determining their accuracy when compared to a professional noise measurement unit. We analyze different candidate algorithms using different types of smartphones, and we study the most adequate time period and sampling strategy to optimize the data-gathering process. In addition, we perform an experimental study comparing our approach with the results obtained using a professional device. Experimental results show that, if the smartphone application is well tuned, it is possible to measure noise levels with a accuracy degree comparable to professional devices for the entire dynamic range typically supported by microphones embedded in smartphones, i.e., 35–95 dB. PMID:28430126

Refinements to the method of epicentral location based on surface waves from ambient seismic noise: introducing Love waves

Science.gov (United States)

Levshin, Anatoli L.; Barmin, Mikhail P.; Moschetti, Morgan P.; Mendoza, Carlos; Ritzwoller, Michael H.

2012-01-01

The purpose of this study is to develop and test a modification to a previous method of regional seismic event location based on Empirical Green’s Functions (EGFs) produced from ambient seismic noise. Elastic EGFs between pairs of seismic stations are determined by cross-correlating long ambient noise time-series recorded at the two stations. The EGFs principally contain Rayleigh- and Love-wave energy on the vertical and transverse components, respectively, and we utilize these signals between about 5 and 12 s period. The previous method, based exclusively on Rayleigh waves, may yield biased epicentral locations for certain event types with hypocentral depths between 2 and 5 km. Here we present theoretical arguments that show how Love waves can be introduced to reduce or potentially eliminate the bias. We also present applications of Rayleigh- and Love-wave EGFs to locate 10 reference events in the western United States. The separate Rayleigh and Love epicentral locations and the joint locations using a combination of the two waves agree to within 1 km distance, on average, but confidence ellipses are smallest when both types of waves are used.

3D shear wave velocity structure revealed with ambient noise tomography on a DAS array

Science.gov (United States)

Zeng, X.; Thurber, C. H.; Wang, H. F.; Fratta, D.

2017-12-01

An 8700-m Distributed Acoustic Sensing (DAS) cable was deployed at Brady's Hot Springs, Nevada in March 2016 in a 1.5 by 0.5 km study area. The layout of the DAS array was designed with a zig-zag geometry to obtain relatively uniform areal and varied angular coverage, providing very dense coverage with a one-meter channel spacing. This array continuously recorded signals of a vibroseis truck, earthquakes, and traffic noise during the 15-day deployment. As shown in a previous study (Zeng et al., 2017), ambient noise tomography can be applied to DAS continuous records to image shear wave velocity structure in the near surface. To avoid effects of the vibroseis truck operation, only continuous data recorded during the nighttime was used to compute noise cross-correlation functions for channel pairs within a given linear segment. The frequency band of whitening was set at 5 to 15 Hz and the length of the cross-correlation time window was set to 60 second. The phase velocities were determined using the multichannel analysis of surface waves (MASW) methodology. The phase velocity dispersion curve was then used to invert for shear wave velocity profiles. A preliminarily velocity model at Brady's Hot Springs (Lawrence Livermore National Laboratory, 2015) was used as the starting model and the sensitivity kernels of Rayleigh wave group and phase velocities were computed with this model. As the sensitivity kernel shows, shear wave velocity in the top 200 m can be constrained with Rayleigh wave group and phase velocities in our frequency band. With the picked phase velocity data, the shear wave velocity structure can be obtained via Occam's inversion (Constable et al., 1987; Lai 1998). Shear wave velocity gradually increases with depth and it is generally faster than the Lawrence Livermore National Laboratory (2015) model. Furthermore, that model has limiting constraints at shallow depth. The strong spatial variation is interpreted to reflect the different sediments and

Intérvalo unitario de tiempo de medición para ruido ambiental Unit timing for environmental noise measurements

Directory of Open Access Journals (Sweden)

William A. Giraldo A.

2011-01-01

Full Text Available En las entidades ambientales, los encargados de las mediciones de ruido ambiental y en general todas las personas que de una u otra forma han trabajado en esta temática, en algún momento se han puesto a pensar sobre la representatividad del tiempo unitario de muestreo y la forma de realizar evaluaciones para dar cumplimiento con dicho tiempo, sin que se aumenten considerablemente los costos de medición. En este artículo se plantea una metodología para determinar cómo un intervalo de cierta duración -en este caso, quince (15 minutos- para el muestreo del nivel de presión sonora es representativo para el período de una (1 hora, logrando de esta manera optimizar el uso de los sonómetros "fijos" y proponiendo una estrategia para reducir los costos en las mediciones de ruido ambiental y en general la elaboración de mapas de ruido.The managers of environmental noise measurements in environmental control agencies, or in general every person that work in this subject, have to think on the representativity of the unit measurement time interval, and how to evaluate it in order to get good quality results regarding the unit measurement time without increasing the measurement costs. A methodology for deciding if a certain measuring time interval -in this case, fifteen (15 minutes- is representative of noise pressure levels occurring during one hour, is proposed in this paper. This methodology allows to optimize the use of stationary sound level meters and to propose a strategy for reducing the costs of environmental noise measurements and of the designing of noise maps in general.

Road traffic noise and incident myocardial infarction

DEFF Research Database (Denmark)

Sørensen, Mette; Andersen, Zorana Jovanovic; Nordsborg, Rikke B

2012-01-01

Both road traffic noise and ambient air pollution have been associated with risk for ischemic heart disease, but only few inconsistent studies include both exposures.......Both road traffic noise and ambient air pollution have been associated with risk for ischemic heart disease, but only few inconsistent studies include both exposures....

Shot-noise-limited optical Faraday polarimetry with enhanced laser noise cancelling

International Nuclear Information System (INIS)

Li, Jiaming; Luo, Le; Carvell, Jeff; Cheng, Ruihua; Lai, Tianshu; Wang, Zixin

2014-01-01

We present a shot-noise-limited measurement of optical Faraday rotations with sub-ten-nanoradian angular sensitivity. This extremely high sensitivity is achieved by using electronic laser noise cancelling and phase sensitive detection. Specially, an electronic laser noise canceller with a common mode rejection ratio of over 100 dB was designed and built for enhanced laser noise cancelling. By measuring the Faraday rotation of ambient air, we demonstrate an angular sensitivity of up to 9.0×10 −9  rad/√(Hz), which is limited only by the shot-noise of the photocurrent of the detector. To date, this is the highest angular sensitivity ever reported for Faraday polarimeters in the absence of cavity enhancement. The measured Verdet constant of ambient air, 1.93(3)×10 −9 rad/(G cm) at 633 nm wavelength, agrees extremely well with the earlier experiments using high finesse optical cavities. Further, we demonstrate the applications of this sensitive technique in materials science by measuring the Faraday effect of an ultrathin iron film

Underwater noise from a wave energy converter

DEFF Research Database (Denmark)

Tougaard, Jakob

A recent addition to the anthropogenic sources of underwater noise is offshore wave energy converters. Underwater noise was recorded from the Wavestar wave energy converter located at Hastholm, Denmark (57°7.73´N, 8°37.23´E). The Wavestar is a full-scale test and demonstration converter...... in full operation and start and stop of the converter. Median broad band (10 Hz – 20 kHz) sound pressure level (Leq) was 123 dB re. 1 Pa, irrespective of status of the wave energy converter (stopped, running or starting/stopping). The most pronounced peak in the third-octave spectrum was in the 160 Hz...... significant noise above ambient could be detected above the 250 Hz band. The absolute increase in noise above ambient was very small. L50 third-octave levels in the four bands with the converter running were thus only 1-2 dB above ambient L50 levels. The noise recorded 25 m from the wave energy converter...

Seismic constraints on magma evolution beneath Mount Baekdu (Changbai) volcano from transdimensional Bayesian inversion of ambient noise data

Science.gov (United States)

Kim, Seongryong; Tkalčić, Hrvoje; Rhie, Junkee

2017-07-01

The magmatic process of continental intraplate volcanism (CIV) is difficult to understand due to heterogeneous interactions with the crust and the lithospheric upper mantle. Mount Baekdu (Changbai) volcano (MBV) is one of the prominent CIVs in northeast Asia that has shown a complex history of eruptions and associated magmatic structures. In addition, the relationship between the crustal magmatic structures and upper mantle phenomena are enigmatic due to the lack of consistent seismic constraints for the lithospheric structure. To enhance comprehensive understanding of the MBV magma evolution, we image the lithospheric structure beneath the MBV and surrounding regions using ambient noise data and the following two approaches: (1) multiple measures of ambient noise dispersion are acquired through different methods and (2) a transdimensional Bayesian inversion method is utilized to obtain unbiased results in joint analysis of the multiple data sets. The estimated Earth structure shows a thick crust ( 40 km) and a crustal anomaly with relatively high S wave velocity in the depth range 20-40 km. This type of structure extends to 100 km north from the MBV and is accompanied by the shallow and rapid S wave velocity decrease beneath the mantle lid ( 80 km). Through a comparison with previous P wave models, we interpret this structure as a consequence of compositional partitioning by mafic underplating and overlying cooled felsic layers as a result of fractional crystalization.

Seasonal variation of seismic ambient noise level at King Sejong Station, Antarctica

Science.gov (United States)

Lee, W.; Sheen, D.; Seo, K.; Yun, S.

2009-12-01

The generation of the secondary- or double-frequency (DF) microseisms with dominant frequencies between 0.1 and 0.5 Hz has been explained by nonlinear second-order pressure perturbations on the ocean bottom due to the interference of two ocean waves of equal wavelengths traveling in opposite directions. Korea Polar Research Institute (KOPRI) has been operating a broadband seismic station (KSJ1) at King George Island (KGI), Antarctica, since 2001. Examining the ambient seismic noise level for the period from 2006 to 2008 at KSJ1, we found a significant seasonal variation in the frequency range 0.1-0.5 Hz. Correlation of the DF peaks with significant ocean wave height and peak wave period models indicates that the oceanic infragravity waves in the Drake Passage is a possible source to excite the DF microseisms at KGI. Location of King Sejong Station, Antarctica Seasonal variations of DF peak, significant wave height, and peak wave period

Environmental Resources of Selected Areas of Hawaii: Climate, Ambient Air Quality, and Noise (DRAFT)

Energy Technology Data Exchange (ETDEWEB)

Lombardi, D.A.; Blasing, T.J.; Easterly, C.E.; Hamilton, C.B.

1994-06-01

This report has been prepared to make available and archive background scientific data and related information on climate, ambient air quality, and ambient noise levels collected during the preparation of the environmental impact statement (EIS) for Phases 3 and 4 of the Hawaii Geothermal Project (HGP) as defined by the state of hawaii in its April 1989 proposal to Congress. The US Department of Energy (DOE) published a notice in the Federal Register on May 17, 1994 withdrawing its Notice of Intent of February 14, 1992, to prepare the HGP-EIS. Since the state of Hawaii is no longer pursuing or planning to pursue the HGP, DOE considers the project to be terminated. The report presents a general description of the climate and air quality for the islands of Hawaii (henceforth referred to as Hawaii), Maui, and Oahu. It also presents a literature review as baseline information on the health effects of hydrogen sulfide. the scientific background data and related information is being made available for use by others in conducting future scientific research in these areas. This report describes the environmental resources present in the areas studied (i.e., the affected environment) and does not represent an assessment of environmental impacts.

Automated Processing Workflow for Ambient Seismic Recordings

Science.gov (United States)

Girard, A. J.; Shragge, J.

2017-12-01

Structural imaging using body-wave energy present in ambient seismic data remains a challenging task, largely because these wave modes are commonly much weaker than surface wave energy. In a number of situations body-wave energy has been extracted successfully; however, (nearly) all successful body-wave extraction and imaging approaches have focused on cross-correlation processing. While this is useful for interferometric purposes, it can also lead to the inclusion of unwanted noise events that dominate the resulting stack, leaving body-wave energy overpowered by the coherent noise. Conversely, wave-equation imaging can be applied directly on non-correlated ambient data that has been preprocessed to mitigate unwanted energy (i.e., surface waves, burst-like and electromechanical noise) to enhance body-wave arrivals. Following this approach, though, requires a significant preprocessing effort on often Terabytes of ambient seismic data, which is expensive and requires automation to be a feasible approach. In this work we outline an automated processing workflow designed to optimize body wave energy from an ambient seismic data set acquired on a large-N array at a mine site near Lalor Lake, Manitoba, Canada. We show that processing ambient seismic data in the recording domain, rather than the cross-correlation domain, allows us to mitigate energy that is inappropriate for body-wave imaging. We first develop a method for window selection that automatically identifies and removes data contaminated by coherent high-energy bursts. We then apply time- and frequency-domain debursting techniques to mitigate the effects of remaining strong amplitude and/or monochromatic energy without severely degrading the overall waveforms. After each processing step we implement a QC check to investigate improvements in the convergence rates - and the emergence of reflection events - in the cross-correlation plus stack waveforms over hour-long windows. Overall, the QC analyses suggest that

Spectral Characteristics of Pitot Noise

Science.gov (United States)

Hornung, H. G.; Parziale, N. J.

For experimental studies of transition from laminar to turbulent boundary layer flow it is important to know the ambient noise spectrum in the facility. In supersonic wind tunnels this is often assessed by measuring pitot pressure noise.

Surface-wave tomography of Ireland and surroundings using ambient noise and teleseismic data

Science.gov (United States)

Bonadio, Raffaele; Arroucau, Pierre; Lebedev, Sergei; Meier, Thomas; Schaeffer, Andrew; Licciardi, Andrea; Piana Agostinetti, Nicola

2016-04-01

Ireland's geology is dominated by northeast-southwest structural trends and suture zones, mostly inferred from geological mapping and a few active source seismic experiments. However, their geometry and extent at depth and their continuity across the Irish Sea are still poorly known. Important questions also remain unanswered regarding the thickness and bulk properties of the sedimentary cover at the regional scale, the deformation and flow of the deep crust during the formation of Ireland, the thickness of Ireland's lithosphere today, and the thermal structure and dynamics of the asthenosphere beneath Ireland. In this work, we take advantage of abundant, newly available broadband data from temporary array deployments and permanent seismic networks in Ireland and Great Britain to produce high-resolution models of seismic velocity structure and anisotropy of the lithosphere. We combine Rayleigh and Love phase velocity measurements from waveform cross-correlation using both ambient noise and teleseismic data in order to produce high-quality dispersion curves for periods ranging from 1 to 300 s. The phase velocity measurement procedures are adapted from Meier et al.[2], Lebedev et al.[1] and Soomro et al.[3] and are automated in order to deal with the large amount of data and ensure consistency and reproducibility. For the nearly 200 stations used in this study, we obtain a very large number of dispersion curves from both ambient noise and teleseimic data. Dispersion measurements are then inverted in a tomographic procedure for surface-wave phase velocity maps in a very broad period range. The maps constrain the 3D seismic-velocity structure of the crust and upper mantle underlying Ireland and the Irish Sea. {9} Lebedev, S., T. Meier, R. D. van der Hilst. Asthenospheric flow and origin of volcanism in the Baikal Rift area, Earth Planet. Sci. Lett., 249, 415-424, 2006. Meier, T., K. Dietrich, B. Stockhert, H.P. Harjes, One-dimensional models of shear wave velocity for

Monitoring Instrument Performance in Regional Broadband Seismic Network Using Ambient Seismic Noise

Science.gov (United States)

Ye, F.; Lyu, S.; Lin, J.

2017-12-01

In the past ten years, the number of seismic stations has increased significantly, and regional seismic networks with advanced technology have been gradually developed all over the world. The resulting broadband data help to improve the seismological research. It is important to monitor the performance of broadband instruments in a new network in a long period of time to ensure the accuracy of seismic records. Here, we propose a method that uses ambient noise data in the period range 5-25 s to monitor instrument performance and check data quality in situ. The method is based on an analysis of amplitude and phase index parameters calculated from pairwise cross-correlations of three stations, which provides multiple references for reliable error estimates. Index parameters calculated daily during a two-year observation period are evaluated to identify stations with instrument response errors in near real time. During data processing, initial instrument responses are used in place of available instrument responses to simulate instrument response errors, which are then used to verify our results. We also examine feasibility of the tailing noise using data from stations selected from USArray in different locations and analyze the possible instrumental errors resulting in time-shifts used to verify the method. Additionally, we show an application that effects of instrument response errors that experience pole-zeros variations on monitoring temporal variations in crustal properties appear statistically significant velocity perturbation larger than the standard deviation. The results indicate that monitoring seismic instrument performance helps eliminate data pollution before analysis begins.

Proximity to traffic, ambient air pollution, and community noise in relation to incident rheumatoid arthritis.

Science.gov (United States)

De Roos, Anneclaire J; Koehoorn, Mieke; Tamburic, Lillian; Davies, Hugh W; Brauer, Michael

2014-10-01

The risk of rheumatoid arthritis (RA) has been associated with living near traffic; however, there is evidence suggesting that air pollution may not be responsible for this association. Noise, another traffic-generated exposure, has not been studied as a risk factor for RA. We investigated proximity to traffic, ambient air pollution, and community noise in relation to RA in the Vancouver and Victoria regions of British Columbia, Canada. Cases and controls were identified in a cohort of adults that was assembled using health insurance registration records. Incident RA cases from 1999 through 2002 were identified by diagnostic codes in combination with prescriptions and type of physician (e.g., rheumatologist). Controls were matched to RA cases by age and sex. Environmental exposures were assigned to each member of the study population by their residential postal code(s). We estimated relative risks using conditional logistic regression, with additional adjustment for median income at the postal code. RA incidence was increased with proximity to traffic, with an odds ratio (OR) of 1.37 (95% CI: 1.11, 1.68) for residence ≤ 50 m from a highway compared with residence > 150 m away. We found no association with traffic-related exposures such as PM2.5, nitrogen oxides, or noise. Ground-level ozone, which was highest in suburban areas, was associated with an increased risk of RA (OR = 1.26; 95% CI: 1.18, 1.36 per interquartile range increase). Our study confirms a previously observed association of RA risk with proximity to traffic and suggests that neither noise levels nor traffic-related air pollutants are responsible for this relationship. Additional investigation of neighborhood and individual correlates of residence near roadways may provide new insight into risk factors for RA.

Structure of Suasselkä Postglacial Fault in northern Finland obtained by analysis of ambient seismic noise

Science.gov (United States)

Afonin, Nikita; Kozlovskaya, Elena

2016-04-01

Understanding inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating the continental intraplate seismicity regime. In our study we address this problem using analysis of ambient seismic noise recorded by the temporary DAFNE array in northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä post-glacial fault (SPGF) that was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised the area of about 20 to 100 km and consisted of 8 short-period and 4 broad-band 3-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September, 2011-May, 2013. Recordings of the array have being analyzed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä Gold Mine. As a result, we found several dozens of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green's functions between pairs of stations in the frequency band of 0.1-1 Hz and to calculate correspondent surface wave dispersion curves. After that S-wave velocity models were obtained as a result of dispersion curves inversion using Geopsy software. The results suggest that the area of

Shear-wave velocities beneath the Harrat Rahat volcanic field, Saudi Arabia, using ambient seismic noise analysis

Science.gov (United States)

Civilini, F.; Mooney, W.; Savage, M. K.; Townend, J.; Zahran, H. M.

2017-12-01

We present seismic shear-velocities for Harrat Rahat, a Cenozoic bimodal alkaline volcanic field in west-central Saudi Arabia, using seismic tomography from natural ambient noise. This project is part of an overall effort by the Saudi Geological Survey and the United States Geological Survey to describe the subsurface structure and assess hazards within the Saudi Arabian shield. Volcanism at Harrat Rahat began approximately 10 Ma, with at least three pulses around 10, 5, and 2 Ma, and at least several pulses in the Quaternary from 1.9 Ma to the present. This area is instrumented by 14 broadband Nanometrics Trillium T120 instruments across an array aperture of approximately 130 kilometers. We used a year of recorded natural ambient noise to determine group and phase velocity surface wave dispersion maps with a 0.1 decimal degree resolution for radial-radial, transverse-transverse, and vertical-vertical components of the empirical Green's function. A grid-search method was used to carry out 1D shear-velocity inversions at each latitude-longitude point and the results were interpolated to produce pseudo-3D shear velocity models. The dispersion maps resolved a zone of slow surface wave velocity south-east of the city of Medina spatially correlated with the 1256 CE eruption. A crustal layer interface at approximately 20 km depth was determined by the inversions for all components, matching the results of prior seismic-refraction studies. Cross-sections of the 3D shear velocity models were compared to gravity measurements obtained in the south-east edge of the field. We found that measurements of low gravity qualitatively correlate with low values of shear-velocity below 20 km along the cross-section profile. We apply these methods to obtain preliminary tomography results on the entire Arabian Shield.

Depth and sharpness variations of 410-km and 660-km discontinuities in North China Craton from dense array ambient noise interferometry

Science.gov (United States)

Yao, H.; Feng, J.; Poli, P.; Fang, L.; Wu, Y.

2017-12-01

Recent studies have demonstrated that body waves between pairs of stations can be successfully retrieved from ambient noise cross-correlation at both regional and global scales, although surface waves are the dominant signals. However, it is still difficult to use these retrieved body wave signals to map lateral depth variations of main structural discontinuities or velocity contrasts because of its low signal to noise ratio (SNR). In this research, based on a dense seismic array in eastern North China Craton, reflected P-wave signals from 410-km and 660-km discontinuities can be successfully recovered from ambient noise cross-correlation. To improve SNR of the reflected phases, the cross-correlations are stacked within each bin with the phase-weighted stack (PWS) method. In addition, there exist apparent spatial variations of the relative amplitude ratios between the reflected P410P and P660P phases. The retrieved P410P and P660P phases from stacked correlations reveal lateral variations of both depths and sharpness of the 410-km and 660-km discontinuities along two profiles, which may be related with hot material upwelling and the effect of stagnant Pacific plate in the transition zone beneath North China Craton. The imaging results are generally consistent with the results from teleseismic receiver functions, which demonstrate the possibility of mapping high-resolution topography and sharpness of deep internal discontinuities without earthquake-station geometric limitations. Future joint imaging with both interferometric and passive signals will be better for understanding interface architectures and related dynamic processes of the Earth.

Imaging of upper crustal structure beneath East Java-Bali, Indonesia with ambient noise tomography

Science.gov (United States)

Martha, Agustya Adi; Cummins, Phil; Saygin, Erdinc; Sri Widiyantoro; Masturyono

2017-12-01

The complex geological structures in East Java and Bali provide important opportunities for natural resource exploitation, but also harbor perils associated with natural disasters. Such a condition makes the East Java region an important area for exploration of the subsurface seismic wave velocity structure, especially in its upper crust. We employed the ambient noise tomography method to image the upper crustal structure under this study area. We used seismic data recorded at 24 seismographs of BMKG spread over East Java and Bali. In addition, we installed 28 portable seismographs in East Java from April 2013 to January 2014 for 2-8 weeks, and we installed an additional 28 seismographs simultaneously throughout East Java from August 2015 to April 2016. We constructed inter-station Rayleigh wave Green's functions through cross-correlations of the vertical component of seismic noise recordings at 1500 pairs of stations. We used the Neighborhood Algorithm to construct depth profiles of shear wave velocity (Vs). The main result obtained from this study is the thickness of sediment cover. East Java's southern mountain zone is dominated by higher Vs, the Kendeng basin in the center is dominated by very low Vs, and the Rembang zone (to the North of Kendeng zone) is associated with medium Vs. The existence of structures with oil and gas potential in the Kendeng and Rembang zones can be identified by low Vs.

New Observations of Seismic Group Velocities in the Western Solomon Islands from Cross-Correlation of Ambient Seismic Noise

Science.gov (United States)

Ku, C. S.; You, S. H.; Kuo, Y. T.; Huang, B. S.; Wu, Y. M.; Chen, Y. G.; Taylor, F. W.

2015-12-01

A MW 8.1 earthquake occurred on 1 April 2007 in the western Solomon Islands. Following this event, a damaging tsunami was induced and hit the Island Gizo where the capital city of Western Province of Solomon Islands located. Several buildings of this city were destroyed and several peoples lost their lives during this earthquake. However, during this earthquake, no near source seismic instrument has been installed in this region. The seismic evaluations for the aftershock sequence, the possible earthquake early warning and tsunami warning were unavailable. For the purpose of knowing more detailed information about seismic activity in this region, we have installed 9 seismic stations (with Trillium 120PA broadband seismometer and Q330S 24bit digitizer) around the rupture zone of the 2007 earthquake since September of 2009. Within a decade, it has been demonstrated both theoretically and experimentally that the Green's function or impulse response between two seismic stations can be retrieved from the cross-correlation of ambient noise. In this study, 6 stations' observations which are more complete during 2011/10 ~ 2012/12 period, were selected for the purpose of the cross-correlation analysis of ambient seismic noise. The group velocities at period 2-20 seconds of 15 station-pairs were extracted by using multiple filter technique (MFT) method. The analyzed results of this study presented significant results of group velocities with higher frequency contents than other studies (20-60 seconds in usually cases) and opened new opportunities to study the shallow crustal structure of the western Solomon Islands.

Particulate Matter and Noise Impact Studies of Waste Rock Dump*

African Journals Online (AJOL)

Michael

2016-06-01

Jun 1, 2016 ... (vegetation) among other recommended strategies would control ambient noise ... respiratory system's natural defences and lodge ... Environmental noise monitoring was conducted ..... (1998), “Nocturnal Aircraft Noise and.

Monterey Bay ambient noise profiles using underwater gliders

OpenAIRE

Chandrayadula, Tarun K.; Miller, Chris W.; Joseph, John

2013-01-01

The article of record as published may be found at http://dx.doi.org/10.1121/1.4799131 In 2012, during two separate week-long deployments, underwater gliders outfitted with external hydrophones profiled the upper 100-200 m of the Monterey Bay. The environment contained various noises made by marine mammals, ships, winds, and earthquakes. Unlike hydrophone receivers moored to a fixed location, moving gliders measure noise variability across a wide terrain. However, underwater mobile s...

High-resolution 3-D S-wave Tomography of upper crust structures in Yilan Plain from Ambient Seismic Noise

Science.gov (United States)

Chen, Kai-Xun; Chen, Po-Fei; Liang, Wen-Tzong; Chen, Li-Wei; Gung, YuanCheng

2015-04-01

The Yilan Plain (YP) in NE Taiwan locates on the western YP of the Okinawa Trough and displays high geothermal gradients with abundant hot springs, likely resulting from magmatism associated with the back-arc spreading as attested by the offshore volcanic island (Kueishantao). YP features NS distinctive characteristics that the South YP exhibits thin top sedimentary layer, high on-land seismicity and significant SE movements, relative those of the northern counterpart. A dense network (~2.5 km station interval) of 89 Texan instruments was deployed in Aug. 2014, covering most of the YP and its vicinity. The ray path coverage density of each 0.015 degree cells are greater than 150 km that could provide the robustness assessment of tomographic results. We analyze ambient noise signals to invert a high-resolution 3D S-wave model for shallow velocity structures in and around YP. The aim is to investigate the velocity anomalies corresponding to geothermal resources and the NS geological distinctions aforementioned. We apply the Welch's method to generate empirical Rayleigh wave Green's functions between two stations records of continuous vertical components. The group velocities of thus derived functions are then obtained by the multiple-filter analysis technique measured at the frequency range between 0.25 and 1 Hz. Finally, we implement a wavelet-based multi-scale parameterization technique to construct 3D model of S-wave velocity. Our first month results exhibit low velocity in the plain, corresponding existing sediments, those of whole YP show low velocity offshore YP and those of high-resolution south YP reveal stark velocity contrast across the Sanshin fault. Key words: ambient seismic noises, Welch's method, S-wave, Yilan Plain

Upper crustal structure beneath East Java from ambient noise tomography: A preliminary result

International Nuclear Information System (INIS)

Martha, Agustya Adi; Widiyantoro, Sri; Cummins, Phil; Saygin, Erdinc; Masturyono

2015-01-01

East Java has a fairly complex geological structure. Physiographically East Java can be divided into three zones, i.e. the Southern Mountains zone in the southern part, the Kendeng zone in the middle part, and the Rembang zone in the northern part. Most of the seismic hazards in this region are due to processes in the upper crust. In this study, the Ambient Noise Tomography (ANT) method is used to image the upper crustal structure beneath East Java. We have used seismic waveform data recorded by 8Meteorological, Climatological and Geophysical Agency (BMKG) stationary seismographic stations and 16 portable seismographs installed for 2 to 8 weeks. The data were processed to obtain waveforms fromnoise cross-correlation between pairs of seismographic stations. Our preliminary results indicate that the Kendeng zone, an area of low gravity anomaly, is associated with a low velocity zone. On the other hand, the southern mountain range, which has a high gravity anomaly, is related to a high velocity anomaly as shown by our tomographic images

Upper crustal structure beneath East Java from ambient noise tomography: A preliminary result

Energy Technology Data Exchange (ETDEWEB)

Martha, Agustya Adi [Meteorological, Climatological and Geophysical Agency, Jakarta (Indonesia); Graduate Research on Earthquakes and Active Tectonics, Institut Teknologi Bandung, Bandung (Indonesia); Widiyantoro, Sri [Global Geophysics Group, Institut Teknologi Bandung, Bandung (Indonesia); Center for Disaster Mitigation, Institut Teknologi Bandung, Bandung (Indonesia); Cummins, Phil; Saygin, Erdinc [Research School of Earth Sciences, Australian National University, Canberra (Australia); Masturyono [Meteorological, Climatological and Geophysical Agency, Jakarta (Indonesia)

2015-04-24

East Java has a fairly complex geological structure. Physiographically East Java can be divided into three zones, i.e. the Southern Mountains zone in the southern part, the Kendeng zone in the middle part, and the Rembang zone in the northern part. Most of the seismic hazards in this region are due to processes in the upper crust. In this study, the Ambient Noise Tomography (ANT) method is used to image the upper crustal structure beneath East Java. We have used seismic waveform data recorded by 8Meteorological, Climatological and Geophysical Agency (BMKG) stationary seismographic stations and 16 portable seismographs installed for 2 to 8 weeks. The data were processed to obtain waveforms fromnoise cross-correlation between pairs of seismographic stations. Our preliminary results indicate that the Kendeng zone, an area of low gravity anomaly, is associated with a low velocity zone. On the other hand, the southern mountain range, which has a high gravity anomaly, is related to a high velocity anomaly as shown by our tomographic images.

Crust azimuthal anisotropy beneath the eastern Tibetan Plateau revealed by ambient noise tomography

Science.gov (United States)

Bao, X.; Song, X.

2017-12-01

The continental collision between India and Eurasia in the Cenozoic has resulted in the rise and growth of the vast Tibetan Plateau (TP). Various geodynamic models, such as rigid-block extrusion, continuous deformation, and the mid-lower crustal flow, have been proposed to describe the growth and expansion of eastern Tibet. To better understand the deformation mechanism of the eastern TP, we performed ambient noise tomography using data from permanent and temporary stations and constructed Rayleigh wave azimuthally anisotropic phase-velocity maps at periods from 8 to 30 s, which mainly sample the crustal structure. The dominant direction of fast wave propagation is oriented NW-SE in the northeastern and eastern TP and N-S in the southeastern TP, which is consistent with the trends of main strike-slip faults and the fast polarization directions of SKS waves and suggests vertically coherent deformation. Furthermore, the magnitude of crustal anisotropy is continuous across main strike-slip faults, which contracts with the prediction of rigid-block extrusion model. Taken together, our model supports vertically coherent distributed deformation in the eastern TP.

Structure of the Suasselkä postglacial fault in northern Finland obtained by analysis of local events and ambient seismic noise

Science.gov (United States)

Afonin, Nikita; Kozlovskaya, Elena; Kukkonen, Ilmo; Dafne/Finland Working Group

2017-04-01

Understanding the inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating the continental intraplate seismicity regime. In our study we address this problem using analysis of local seismic events and ambient seismic noise recorded by the temporary DAFNE array in the northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä postglacial fault (SPGF), which was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised an area of about 20 to 100 km and consisted of eight short-period and four broadband three-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September 2011-May 2013. Recordings of the array have being analysed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä gold mine. As a result, we found a number of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single-station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green's functions between pairs of stations in the frequency band of 0.1-1 Hz and to calculate corresponding surface wave dispersion curves. The S-wave velocity models were obtained as a result of dispersion curve inversion. The results suggest that the area of

Radial anisotropy of Northeast Asia inferred from Bayesian inversions of ambient noise data

Science.gov (United States)

Lee, S. J.; Kim, S.; Rhie, J.

2017-12-01

The eastern margin of the Eurasia plate exhibits complex tectonic settings due to interactions with the subducting Pacific and Philippine Sea plates and the colliding India plate. Distributed extensional basins and intraplate volcanoes, and their heterogeneous features in the region are not easily explained with a simple mechanism. Observations of radial anisotropy in the entire lithosphere and the part of the asthenosphere provide the most effective evidence for the deformation of the lithosphere and the associated variation of the lithosphere-asthenosphere boundary (LAB). To infer anisotropic structures of crustal and upper-mantle in this region, radial anisotropy is measured using ambient noise data. In a continuation of previous Rayleigh wave tomography study in Northeast Asia, we conduct Love wave tomography to determine radial anisotropy using the Bayesian inversion techniques. Continuous seismic noise recordings of 237 broad-band seismic stations are used and more than 55,000 group and phase velocities of fundamental mode are measured for periods of 5-60 s. Total 8 different types of dispersion maps of Love wave from this study (period 10-60 s), Rayleigh wave from previous tomographic study (Kim et al., 2016; period 8-70 s) and longer period data (period 70-200 s) from a global model (Ekstrom, 2011) are jointly inverted using a hierarchical and transdimensional Bayesian technique. For each grid-node, boundary depths, velocities and anisotropy parameters of layers are sampled simultaneously on the assumption of the layered half-space model. The constructed 3-D radial anisotropy model provides much more details about the crust and upper mantle anisotropic structures, and about the complex undulation of the LAB.

Potential Impacts of Ambient Noise in the on Marine Mammals

National Research Council Canada - National Science Library

Frisk, George

2003-01-01

The Committee was charged with assessing our state of knowledge of underwater noise and recommending research areas to assist in determining whether noise in the ocean adversely affects marine mammals...

An investigation of time-frequency domain phase-weighted stacking and its application to phase-velocity extraction from ambient noise's empirical Green's functions

Science.gov (United States)

Li, Guoliang; Niu, Fenglin; Yang, Yingjie; Xie, Jun

2018-02-01

The time-frequency domain phase-weighted stacking (tf-PWS) technique based on the S transform has been employed in stacking empirical Green's functions (EGFs) derived from ambient noise data, mainly due to its superior power in enhancing weak signals. Questions such as the induced waveform distortion and the feasibility of phase-velocity extraction are yet to be thoroughly explored. In this study, we investigate these issues by conducting extensive numerical tests with both synthetic data and USArray transportable array (TA) ambient noise data. We find that the errors in the measured phase velocities associated with waveform distortion caused by the tf-PWS depend largely on the way of how the inverse S transform (IST) is implemented. If frequency IST is employed in tf-PWS, the corresponding errors are generally less than 0.1 per cent, sufficiently small that the measured phase velocities can be safely used in regular surface wave tomography. On the other hand, if a time IST is used in tf-PWS, then the extracted phase velocities are systematically larger than those measured from linearly stacked ones, and the discrepancy can reach as much as ˜0.4 per cent at some periods. Therefore, if tf-PWS is used in stacking EGFs, then frequency IST is preferred to transform the stacked S spectra back to the time domain for the stacked EGFs.

Ambient diagnostics

CERN Document Server

Cai, Yang

2014-01-01

Part I. FundamentalsIntroductionWhat is Ambient Diagnostics?Diagnostic ModelsMultimedia IntelligenceCrowd SourcingSoft SensorsScience of SimplicityPersonal DiagnosesBasic AlgorithmsBasic ToolsSummaryProblemsTransformationEarly Discoveries of Heartbeat PatternsTransforms, Features, and AttributesSequential FeaturesSpatiotemporal FeaturesShape FeaturesImagery FeaturesFrequency Domain FeaturesMulti-Resolution FeaturesSummaryProblemsPattern RecognitionSimilarities and DistancesClustering MethodsClassification MethodsClassifier Accuracy MeasuresSummaryProblemsPart II. Multimedia IntelligenceSound RecognitionMicrophone AppsModern Acoustic Transducers (Microphones)Frequency Response CharacteristicsDigital Audio File FormatsHeart Sound SensingLung Sound SensingSnore MeterSpectrogram (STFT)Ambient Sound AnalysisSound RecognitionRecognizing Asthma SoundPeak ShiftFeature CompressionRegroupingNoise IssuesFuture ApplicationsSummaryProblemsColor SensorsColor SensingHuman Color VisionColor SensorsColor Matching ExperimentsC...

Imaging San Jacinto Fault damage zone structure using dense linear arrays: application of ambient noise tomography, Rayleigh wave ellipticity, and site amplification

Science.gov (United States)

Wang, Y.; Lin, F. C.; Allam, A. A.; Ben-Zion, Y.

2017-12-01

The San Jacinto fault is presently the most seismically active component of the San Andreas Transform system in Southern California. To study the damage zone structure, two dense linear geophone arrays (BS and RR) were deployed across the Clark segment of the San Jacinto Fault between Anza and Hemet during winter 2015 and Fall 2016, respectively. Both arrays were 2 km long with 20 m station spacing. Month-long three-component ambient seismic noise data were recorded and used to calculate multi-channel cross-correlation functions. All three-component noise records of each array were normalized simultaneously to retain relative amplitude information between different stations and different components. We observed clear Rayleigh waves and Love waves on the cross-correlations of both arrays at 0.3 - 1 s period. The phase travel times of the Rayleigh waves on both arrays were measured by frequency-time analysis (FTAN), and inverted for Rayleigh wave phase velocity profiles of the upper 500 m depth. For both arrays, we observe prominent asymmetric low velocity zones which narrow with depth. At the BS array near the Hemet Stepover, an approximately 250m wide slow zone is observed to be offset by 75m to the northeast of the surface fault trace. At the RR array near the Anza segment of the fault, a similar low velocity zone width and offset are observed, along with a 10% across-fault velocity contrast. Analyses of Rayleigh wave ellipticity (H/V ratio), Love wave phase travel times, and site amplification are in progress. By using multiple measurements from ambient noise cross-correlations, we can obtain strong constraints on the local damage zone structure of the San Jacinto Fault. The results contribute to improved understanding of rupture directivity, maximum earthquake magnitude and more generally seismic hazard associated with the San Jacinto fault zone.

Natural and anthropogenic ocean noise recorded at long-term and temporary observatories

Science.gov (United States)

Grevemeyer, Ingo; Metz, Dirk; Watts, Anthony B.; Geissler, Wolfram

2017-04-01

Most people worldwide would assume that the oceans are silent. However, a number of natural phenomenon's like ocean waves, wind, lightening, ice noise, earthquakes, and submarine volcanic activity contributes to the ambient ocean noise. During their evolution, marine animals like fish and mammals have adopted in many ways to the acoustic properties of the sea. Yet in recent decades, anthropogenic and hence manmade ocean noise level has risen profoundly. Due to extreme reliance of fish and mammals on underwater sounds for basic life functions, including searching for food or mate and the absence of any mechanism to safeguard them against it, underwater noise pollution may disrupt marine life. The primary sources of low-frequency anthropogenic noise include sounds associated with shipping, military operations, oil and gas exploration and production, and even research activities. Some scientists suggest that today virtually no marine environment is without any noise pollution. Thus, all marine life forms that rely heavily on the integrity of their acoustic habitat may have to adapt to new conditions. Of greatest concern for whales are low-frequency sounds that travel long distances in the ocean. Ship propellers and motors, for instance, produce sound at low frequencies, as do natural and manmade seismic activity. These profound, loud noises reverberate in the deep ocean and can effectively mask or block vital whale communication. However, in general very little is known about the world-wide distribution of ambient ocean noise. Thus, on a global scale and considering the vast areas of the world's oceans, we know virtually nothing about noise levels in different parts of the oceans and how anthropogenic noise contributes to ambient noise. Here, we use hydrophone recordings from the UN's Comprehensive Nuclear-Test-Ban Treaty organization (CTBTO) and ocean-bottom seismometers to provide an assessment of noise in all major basins, including the Pacific, Atlantic and Indian

Noise cancellation in magnetoencephalography and electroencephalography with isolated reference sensors

Science.gov (United States)

Kraus, Jr., Robert H.; Espy, Michelle A.; Matlachov, Andrei; Volegov, Petr

2010-06-01

An apparatus measures electromagnetic signals from a weak signal source. A plurality of primary sensors is placed in functional proximity to the weak signal source with an electromagnetic field isolation surface arranged adjacent the primary sensors and between the weak signal source and sources of ambient noise. A plurality of reference sensors is placed adjacent the electromagnetic field isolation surface and arranged between the electromagnetic isolation surface and sources of ambient noise.

The functions of sound production in the lined seahorse, Hippocampus erectus, and effects of loud ambient noise on its behavior and physiology in captive environments

Science.gov (United States)

Anderson, Paul August

Loud noise in aquaria represents a cacophonous environment for captive fishes. I tested the effects of loud noise on acoustic communication, feeding behavior, courtship behavior, and the stress response of the lined seahorse, Hippocampus erectus. Total Root Mean Square (RMS) power of ambient noise to which seahorses are exposed in captivity varies widely but averages 126.1 +/- 0.8 deciBels with reference to one micropascal (dB re: 1 muPa) at the middle of the water column and 133.7 +/- 1.1 dB at the tank bottom, whereas ambient noise in the wild averages 119.6 +/- 3.5 dB. Hearing sensitivity of H. erectus, measured from auditory evoked potentials, demonstrated maximum spectrum-level sensitivities of 105.0 +/- 1.5 dB and 3.5 x 10-3 + 7.6 x 10-4 m/s2 at 200 Hz; which is characteristic of hearing generalists. H. erectus produces acoustic clicks with mean peak spectrum-level amplitudes of 94.3 +/- 0.9 dB at 232 +/- 16 Hz and 1.5 x 10 -3 +/- 1.9 x 10-4 m/s2 at 265 +/- 22 Hz. Frequency matching of clicks to best hearing sensitivity, and estimates of audition of broadband signals suggest that seahorses may hear conspecific clicks, especially in terms of particle motion. Behavioral investigations revealed that clicking did not improve prey capture proficiency. However, animals clicked more often as time progressed in a courtship sequence, and mates performed more courtship behaviors with control animals than with muted animals, lending additional evidence to the role of clicking as an acoustic signal during courtship. Despite loud noise and the role of clicking in communication, masking of the acoustic signal was not demonstrated. Seahorses exposed to loud noise in aquaria for one month demonstrated physiological, chronic stress responses: reduced weight and body condition, and increased heterophil to lymphocyte ratio. Behavioral alterations were characterized by greater mean and variance of activity among animals housed in loud tanks in the first week, followed by

Low-noise wide-band amplifiers for stochastic beam cooling experiments

International Nuclear Information System (INIS)

Leskovar, B.; Lo, C.C.

1982-01-01

Noise characteristics of the continuous-wave wide-band amplifier systems for stochastic beam cooling experiments are presented. Also, the noise performance, bandwidth capability and gain stability of components used in these amplifiers are summarized and compared in the 100 MHz to 40 GHz frequency range. This includes bipolar and field-effect transistors, parametric amplifier, Schottky diode mixer and maser. Measurements of the noise characteristics and scattering parameters of variety GaAs FETs as a function of ambient temperature are also given. Performance data and design information are presented on a broadband 150-500 MHz preamplifier having noise temperature of approximately 35 0 K at ambient temperature of 20 0 K. An analysis of preamplifier stability based on scattering parameters concept is included

Sources and levels of ambient ocean sound near the Antarctic Peninsula.

Directory of Open Access Journals (Sweden)

Robert P Dziak

Full Text Available Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (Antarctic Peninsula region from 2005 to 2009 to record ambient ocean sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the ocean soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10-20 dB higher in the open, deep ocean of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue (Balaenoptera musculus and fin (B. physalus whales also dominate the long-term spectra records in the 15-28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns, likely due to low coastal traffic and the typically rough weather and sea conditions of the Southern Ocean.

On the Retrieval of the Directional Scattering Matrix from Directional Noise

NARCIS (Netherlands)

Wapenaar, C.P.A.; Thorbecke, J.W.

2013-01-01

The crosscorrelation of ambient acoustic noise observed at two receivers yields the impulse response between these receivers, assuming that the noise field is diffuse. In practical situations the noise field exhibits directionality, which imprints the angle-dependent correlation function. For the

Full-wave Ambient Noise Tomography of Mt Rainier volcano, USA

Science.gov (United States)

Flinders, Ashton; Shen, Yang

2015-04-01

Mount Rainier towers over the landscape of western Washington (USA), ranking with Fuji-yama in Japan, Mt Pinatubo in the Philippines, and Mt Vesuvius in Italy, as one of the great stratovolcanoes of the world. Notwithstanding its picturesque stature, Mt Rainier is potentially the most devastating stratovolcano in North America, with more than 3.5 million people living beneath is shadow in the Seattle-Tacoma area. The primary hazard posed by the volcano is in the form of highly destructive debris flows (lahars). These lahars form when water and/or melted ice erode away and entrain preexisting volcanic sediment. At Mt Rainier these flows are often initiated by sector collapse of the volcano's hydrothermally rotten flanks and compounded by Mt Rainier's extensive snow and glacial ice coverage. It is therefore imperative to ascertain the extent of the volcano's summit hydrothermal alteration, and determine areas prone to collapse. Despite being one of the sixteen volcanoes globally designated by the International Association of Volcanology and Chemistry of the Earth's Interior as warranting detailed and focused study, Mt Rainier remains enigmatic both in terms of the shallow internal structure and the degree of summit hydrothermal alteration. We image this shallow internal structure and areas of possible summit alteration using ambient noise tomography. Our full waveform forward modeling includes high-resolution topography allowing us to accuratly account for the effects of topography on the propagation of short-period Rayleigh waves. Empirical Green's functions were extracted from 80 stations within 200 km of Mt Rainier, and compared with synthetic greens functions over multiple frequency bands from 2-28 seconds.

Full waveform ambient noise tomography of Mount Rainer

Science.gov (United States)

Flinders, A. F.; Shen, Y.

2014-12-01

Mount Rainier towers over the landscape of western Washington, ranking with Fuji-yama in Japan, Mt. Pinatubo in the Philippines, and Mt. Vesuvius in Italy, as one of the great stratovolcanoes of the world. Notwithstanding it's picturesque stature, Mt. Rainier is potentially the most devastating stratovolcano in North America, with more than 3.5 million people living beneath its shadow in the Seattle-Tacoma area. The primary hazard posed by the volcano is in the form of highly destructive volcanic debris flows (lahars). These lahars form when water and/or melted ice erode away and entrain preexisting volcanic sediment. At Mt. Rainier these flows are often initiated by sector collapse of the volcano's hydrothermally rotten flanks and compounded from Mt. Rainier's extensive snow and glacial ice coverage. It is therefore imperative to ascertain the extent of summit hydrothermal alteration within the volcano, and determine areas prone to collapse. Despite being one of the sixteen volcanoes globally designated by the International Association of Volcanology and Chemistry of the Earth's Interior as warranting detailed and focused study, Mt. Rainier remains enigmatic both in terms of shallow internal structure and the degree of summit hydrothermal alteration. We image this shallow internal structure and areas of possible summit alteration using ambient noise tomography. Our full waveform forward modeling includes high-resolution topography, allowing us to accurately account for the effects of topography on the propagation of short-period Rayleigh waves. Empirical Green's functions were extracted from 80 stations within 200 km of Mount Rainier and compared with synthetic greens functions over multiple frequency bands from 2-28 seconds. The preliminary model shows a broad (60 km wide) low shear-wave velocity anomaly in the mid-crust beneath the volcano. The mid-crust low-velocity body extends to the surface beneath the volcano summit in a narrow near-vertical conduit, the

Jet Noise Scaling in Dual Stream Nozzles

Science.gov (United States)

Khavaran, Abbas; Bridges, James

2010-01-01

Power spectral laws in dual stream jets are studied by considering such flows a superposition of appropriate single-stream coaxial jets. Noise generation in each mixing region is modeled using spectral power laws developed earlier for single stream jets as a function of jet temperature and observer angle. Similarity arguments indicate that jet noise in dual stream nozzles may be considered as a composite of four single stream jets representing primary/secondary, secondary/ambient, transition, and fully mixed zones. Frequency filter are designed to highlight spectral contribution from each jet. Predictions are provided at an area ratio of 2.0--bypass ratio from 0.80 to 3.40, and are compared with measurements within a wide range of velocity and temperature ratios. These models suggest that the low frequency noise in unheated jets is dominated by the fully mixed region at all velocity ratios, while the high frequency noise is dominated by the secondary when the velocity ratio is larger than 0.80. Transition and fully mixed jets equally dominate the low frequency noise in heated jets. At velocity ratios less than 0.50, the high frequency noise from primary/bypass becomes a significant contributing factor similar to that in the secondary/ambient jet.

Does ambient noise or hypobaric atmosphere influence olfactory and gustatory function?

Science.gov (United States)

Rahne, Torsten; Köppke, Robert; Nehring, Michael; Plontke, Stefan K; Fischer, Hans-Georg

2018-01-01

Multidimensional food perception is based mainly on gustatory and olfactory function. Recent research has demonstrated that hypobaric pressure impairs gustatory function and that background noise or distracting auditory stimulation impairs olfactory function. Using a hypobaric chamber, the odor identification, discrimination, and thresholds as well as taste identification and threshold scores were measured in 16 healthy male volunteers under normal and hypobaric (6380 ft) conditions using clinically validated tests. In both conditions, background noise was either canceled out or replaced by white noise presentation (70 dB sound pressure level). Olfactory sensitivity for n-butanol and gustatory sensitivity were impaired in a hypobaric atmosphere. White noise did not influence the odor test results. White noise stimulation impaired sensitivity for sour and sweet but not for bitter or salty tastants. We conclude that hypobaric or noisy environments could impair gustatory and olfactory sensitivity selectively for particular tastants and odorants.

Noise problems in coal mining complex- a case discussion

International Nuclear Information System (INIS)

Mishra, Y.; Mitra, H.; Ghosh, S.; Pal, A.K.

1996-01-01

Noise monitoring study was conducted at Moonidih mining complex of Jharia coal-field. The study included monitoring and analysis of ambient as well as workplace noise levels. An attempt has been made to critically analyse the noise situation through octave band analysis, thereby identifying alarming noise frequencies for each noise generating equipment having Leq level more than 90 dBA. A noise model has also been developed to draw noise contours of the entire mining complex. Based on these studies, suitable control measures have been suggested. (author). 6 refs., 3 figs

Impact of Vessel Noise on Oyster Toadfish (Opsanus tau) Behavior and Implications for Underwater Noise Management

Science.gov (United States)

Krahforst, Cecilia S.

Underwater noise and its impacts on marine life are growing management concerns. This dissertation considers both the ecological and social concerns of underwater noise, using the oyster toadfish (Opsanus tau) as a model species. Oyster toadfish call for mates using a boatwhistle sound, but increased ambient noise levels from vessels or other anthropogenic activities are likely to influence the ability of males to find mates. If increased ambient noise levels reduce fish fitness then underwater noise can impact socially valued ecosystem services (e.g. fisheries). The following ecological objectives of the impacts of underwater noise on oyster toadfish were investigated: (1) to determine how noise influences male calling behavior; (2) to assess how areas of high vessel activity ("noisy") and low vessel activity ("quiet") influence habitat utilization (fish standard length and occupancy rate); and (3) to discover if fitness (number of clutches and number of embryos per clutch) is lower in "noisy" compared with "quiet" sites. Field experiments were executed in "noisy" and "quiet" areas. Recorded calls by males in response to playback sounds (vessel, predator, and snapping shrimp sounds) and egg deposition by females ("noisy" vs. "quiet" sites) demonstrated that oyster toadfish are impacted by underwater noise. First, males decreased their call rates and called louder in response to increased ambient noise levels. Second, oyster toadfish selected nesting sites in areas with little or no inboard motorboat activity. Third, male oyster toadfish at "noisy" sites either had no egg clutches on their shelters or the number of embryos per clutch was significantly lower than in the "quiet" areas. Underwater noise and disturbance from vessels are influencing the fitness of the oyster toadfish. The social significance of the growing concerns regarding underwater noise was investigated by identifying dominant themes found within two types of texts: four recent underwater noise

Shallow crustal radial anisotropy beneath the Tehran basin of Iran from seismic ambient noise tomography

Science.gov (United States)

Shirzad, Taghi; Shomali, Z. Hossein

2014-06-01

We studied the shear wave velocity structure and radial anisotropy beneath the Tehran basin by analyzing the Rayleigh wave and Love wave empirical Green's functions obtained from cross-correlation of seismic ambient noise. Approximately 199 inter-station Rayleigh and Love wave empirical Green's functions with sufficient signal-to-noise ratios extracted from 30 stations with various sensor types were used for phase velocity dispersion analysis of periods ranging from 1 to 7 s using an image transformation analysis technique. Dispersion curves extracted from the phase velocity maps were inverted based on non-linear damped least squares inversion method to obtain a quasi-3D model of crustal shear wave velocities. The data used in this study provide an unprecedented opportunity to resolve the spatial distribution of radial anisotropy within the uppermost crust beneath the Tehran basin. The quasi-3D shear wave velocity model obtained in this analysis delineates several distinct low- and high-velocity zones that are generally separated by geological boundaries. High-shear-velocity zones are located primarily around the mountain ranges and extend to depths of 2.0 km, while the low-shear-velocity zone is located near regions with sedimentary layers. In the shallow subsurface, our results indicate strong radial anisotropy with negative magnitude (VSV > VSH) primarily associated with thick sedimentary deposits, reflecting vertical alignment of cracks. With increasing depth, the magnitude of the radial anisotropy shifts from predominantly negative (less than -10%) to predominantly positive (greater than 5%). Our results show a distinct change in radial anisotropy between the uppermost sedimentary layer and the bedrock.

Near-source noise suppression of AMT by compressive sensing and mathematical morphology filtering

Science.gov (United States)

Li, Guang; Xiao, Xiao; Tang, Jing-Tian; Li, Jin; Zhu, Hui-Jie; Zhou, Cong; Yan, Fa-Bao

2017-12-01

In deep mineral exploration, the acquisition of audio magnetotelluric (AMT) data is severely affected by ambient noise near the observation sites; This near-field noise restricts investigation depths. Mathematical morphological filtering (MMF) proved effective in suppressing large-scale strong and variably shaped noise, typically low-frequency noise, but can not deal with pulse noise of AMT data. We combine compressive sensing and MMF. First, we use MMF to suppress the large-scale strong ambient noise; second, we use the improved orthogonal match pursuit (IOMP) algorithm to remove the residual pulse noise. To remove the noise and protect the useful AMT signal, a redundant dictionary that matches with spikes and is insensitive to the useful signal is designed. Synthetic and field data from the Luzong field suggest that the proposed method suppresses the near-source noise and preserves the signal well; thus, better results are obtained that improve the output of either MMF or IOMP.

Understanding the amplitudes of noise correlation measurements

Science.gov (United States)

Tsai, Victor C.

2011-01-01

Cross correlation of ambient seismic noise is known to result in time series from which station-station travel-time measurements can be made. Part of the reason that these cross-correlation travel-time measurements are reliable is that there exists a theoretical framework that quantifies how these travel times depend on the features of the ambient noise. However, corresponding theoretical results do not currently exist to describe how the amplitudes of the cross correlation depend on such features. For example, currently it is not possible to take a given distribution of noise sources and calculate the cross correlation amplitudes one would expect from such a distribution. Here, we provide a ray-theoretical framework for calculating cross correlations. This framework differs from previous work in that it explicitly accounts for attenuation as well as the spatial distribution of sources and therefore can address the issue of quantifying amplitudes in noise correlation measurements. After introducing the general framework, we apply it to two specific problems. First, we show that we can quantify the amplitudes of coherency measurements, and find that the decay of coherency with station-station spacing depends crucially on the distribution of noise sources. We suggest that researchers interested in performing attenuation measurements from noise coherency should first determine how the dominant sources of noise are distributed. Second, we show that we can quantify the signal-to-noise ratio of noise correlations more precisely than previous work, and that these signal-to-noise ratios can be estimated for given situations prior to the deployment of seismometers. It is expected that there are applications of the theoretical framework beyond the two specific cases considered, but these applications await future work.

Underwater Ambient Noise in a Baleen Whale Migratory Habitat Off the Azores

Directory of Open Access Journals (Sweden)

Miriam Romagosa

2017-04-01

Full Text Available Assessment of underwater noise is of particular interest given the increase in noise-generating human activities and the potential negative effects on marine mammals which depend on sound for many vital processes. The Azores archipelago is an important migratory and feeding habitat for blue (Balaenoptera musculus, fin (Balaenoptera physalus and sei whales (Balaenoptera borealis en route to summering grounds in northern Atlantic waters. High levels of low frequency noise in this area could displace whales or interfere with foraging behavior, impacting energy intake during a critical stage of their annual cycle. In this study, bottom-mounted Ecological Acoustic Recorders were deployed at three Azorean seamounts (Condor, Açores, and Gigante to measure temporal variations in background noise levels and ship noise in the 18–1,000 Hz frequency band, used by baleen whales to emit and receive sounds. Monthly average noise levels ranged from 90.3 dB re 1 μPa (Açores seamount to 103.1 dB re 1 μPa (Condor seamount and local ship noise was present up to 13% of the recording time in Condor. At this location, average contribution of local boat noise to background noise levels is almost 10 dB higher than wind contribution, which might temporally affect detection ranges for baleen whale calls and difficult communication at long ranges. Given the low time percentatge with noise levels above 120 dB re 1 μPa found here (3.3% at Condor, we woud expect limited behavioral responses to ships from baleen whales. Sound pressure levels measured in the Azores are lower than those reported for the Mediterranean basin and the Strait of Gibraltar. However, the currently unknown effects of baleen whale vocalization masking and the increasing presence of boats at the monitored sites underline the need for continuous monitoring to understand any long-term impacts on whales.

Impact of noise and air pollution on pregnancy outcomes

NARCIS (Netherlands)

Gehring, Ulrike; Tamburic, Lillian; Sbihi, Hind; Davies, Hugh W.; Brauer, Michael

2014-01-01

Background: Motorized traffic is an important source of both air pollution and community noise. While there is growing evidence for an adverse effect of ambient air pollution on reproductive health, little is known about the association between traffic noise and pregnancy outcomes. Methods: We

Noise-Induced Hearing Loss - A Preventable Disease? Results of a 10-Year Longitudinal Study of Workers Exposed to Occupational Noise.

Science.gov (United States)

Frederiksen, Thomas W; Ramlau-Hansen, Cecilia H; Stokholm, Zara A; Grynderup, Matias B; Hansen, Åse M; Kristiansen, Jesper; Vestergaard, Jesper M; Bonde, Jens P; Kolstad, Henrik A

2017-01-01

To survey current, Danish industrial noise levels and the use of hearing protection devices (HPD) over a 10-year period and to characterise the association between occupational noise and hearing threshold shift in the same period. Furthermore, the risk of hearing loss among the baseline and the follow-up populations according to first year of occupational noise exposure is evaluated. In 2001-2003, we conducted a baseline survey of noise- and hearing-related disorders in 11 industries with suspected high noise levels. In 2009-2010, we were able to follow up on 271 out of the 554 baseline workers (49%). Mean noise levels per industry and self-reported HPD use are described at baseline and follow-up. The association between cumulative occupational noise exposure and hearing threshold shift over the 10-year period was assessed using linear regression, and the risk of hearing loss according to year of first occupational noise exposure was evaluated with logistic regression. Over the 10-year period, mean noise levels declined from 83.9 dB(A) to 82.8 dB(A), and for workers exposed >85 dB(A), the use of HPD increased from 70.1 to 76.1%. We found a weak, statistically insignificant, inverse association between higher ambient cumulative noise exposure and poorer hearing (-0.10 dB hearing threshold shift per dB-year (95% confidence interval (CI): -0.36; 0.16)). The risk of hearing loss seemed to increase with earlier first year of noise exposure, but odds ratios were only statistically significant among baseline participants with first exposure before the 1980s (odds ratio: 1.90, 95% CI: 1.11; 3.22). We observed declining industrial noise levels, increased use of HPD and no significant impact on hearing thresholds from current ambient industrial noise levels, which indicated a successful implementation of Danish hearing conservation programs.

Time-Lapse Monitoring of an Engineering Scaled Excavation at Federal District, Brazil by Passive Ambient NoiseInterferometry

Science.gov (United States)

Cárdenas-Soto, M., Sr.; Hussain, Y.; Martinez-Carvajal, H., Sr.; Martino, S., Sr.; Rocha, M., Sr.

2016-12-01

Understanding the dynamics of stress relief mechanisms that lead to complete material collapse of unstable slopes is challenging. This research is focused on the novel use of Passive Ambient Noise Interferometry (PANI), a new technique that has revolutionized the seismology. In this technique the impulse response or Green function between two sensors is calculated by cross-correlation of the noise rescored at these stations. We applied PANI to monitor the deformational behavior of a prototype field experiment under semi controlled conditions for their use in landsliding early warning systems.The experimental setup consists of a 2 m engineering-scaled excavation,where induced failure was monitored by ambient vibrations propagating in tropical clayey deposits. The experimental setup consisted of dense network of 20 three components short period seismometers (Sercel L4C-3D) installed in three circular arrays with their distances from face of normal slope as 10, 20 and 30 meters, respectively.The frequency response of these seismometers is in range of 2-100 Hz. Recording was done in continuous mode at sampling rate of 1000 Hz with datalogger (RefTek DAS-130/3). Sensors were time synchronized by twenty 130 GPS/01. In this stage, the stress was applied on the one flank of this normal slope dug in the experimental field of University of Brasilia, by a hydraulic jack through a metallic plate. This incremental loading was kept on rising until the slope failure took place. This loading mechanism provided an opportunity to monitoring the changes in Rayleigh wave velocity before, during and after the complete failure. After initial processing, the green function (GF) or impulse response was calculated between each pair of sensors by cross correlation at time step of 4 second. All individual GFs, for entire monitoring period (30 minutes) were stacked to obtained a single reference GF. Stretching (dt/t) in waveform is calculated by subtracting individual GF from average GF, that

Listening to the Deep-Ocean Environment (LIDO): an ESONET Initiative for the Real-Time Monitoring of Geohazards and Marine Ambient Noise

Science.gov (United States)

André, Michel; Favali, Paolo; Piatteli, Paolo; Miranda, Jorge; Waldmann, Christoph; Esonet Lido Demonstration Mission Team

2010-05-01

Understanding the link between natural and anthropogenic processes is essential for predicting the magnitude and impact of future changes of the natural balance of the oceans. Deep-sea observatories have the potential to play a key role in the assessment and monitoring of these changes. ESONET is a European Network of Excellence of deep-sea observatories that includes 55 partners belonging to 14 countries. ESONET NoE is providing data on key parameters from the subsurface down to the seafloor at representative locations that transmit them to shore. The strategies of deployment, data sampling, technological development, standardisation and data management are being integrated with projects dealing with the spatial and near surface time series. LIDO (Listening to the Deep Ocean environment) is one of these projects and proposes to establish a first nucleus of a regional network of multidisciplinary seafloor observatories contributing to the coordination of high quality research in the ESONET NoE by allowing the real-time long-term monitoring of Geohazards and Marine Ambient Noise in the Mediterranean Sea and the adjacent Atlantic waters. Specific activities address the long-term monitoring of earthquakes and tsunamis and the characterisation of ambient noise, marine mammal sounds and anthropogenic sources. The objective of this demonstration mission will be achieved through the extension of the present capabilities of the observatories working in the ESONET key-sites of Eastern Sicily (NEMO-SN1) and of the Gulf of Cadiz (GEOSTAR configured for NEAREST pilot experiment) by installing new sensor equipments related to Bioacoustics and Geohazards, as well as by implementing international standard methods in data acquisition and management.

Noise-driven manifestation of learning in mature neural networks

International Nuclear Information System (INIS)

Monterola, Christopher; Saloma, Caesar

2002-01-01

We show that the generalization capability of a mature thresholding neural network to process above-threshold disturbances in a noise-free environment is extended to subthreshold disturbances by ambient noise without retraining. The ability to benefit from noise is intrinsic and does not have to be learned separately. Nonlinear dependence of sensitivity with noise strength is significantly narrower than in individual threshold systems. Noise has a minimal effect on network performance for above-threshold signals. We resolve two seemingly contradictory responses of trained networks to noise--their ability to benefit from its presence and their robustness against noisy strong disturbances

Motorboat noise impacts parental behaviour and offspring survival in a reef fish.

Science.gov (United States)

Nedelec, Sophie L; Radford, Andrew N; Pearl, Leanne; Nedelec, Brendan; McCormick, Mark I; Meekan, Mark G; Simpson, Stephen D

2017-06-14

Anthropogenic noise is a pollutant of international concern, with mounting evidence of disturbance and impacts on animal behaviour and physiology. However, empirical studies measuring survival consequences are rare. We use a field experiment to investigate how repeated motorboat-noise playback affects parental behaviour and offspring survival in the spiny chromis ( Acanthochromis polyacanthus ), a brooding coral reef fish. Repeated observations were made for 12 days at 38 natural nests with broods of young. Exposure to motorboat-noise playback compared to ambient-sound playback increased defensive acts, and reduced both feeding and offspring interactions by brood-guarding males. Anthropogenic noise did not affect the growth of developing offspring, but reduced the likelihood of offspring survival; while offspring survived at all 19 nests exposed to ambient-sound playback, six of the 19 nests exposed to motorboat-noise playback suffered complete brood mortality. Our study, providing field-based experimental evidence of the consequences of anthropogenic noise, suggests potential fitness consequences of this global pollutant. © 2017 The Authors.

High level white noise generator

International Nuclear Information System (INIS)

Borkowski, C.J.; Blalock, T.V.

1979-01-01

A wide band, stable, random noise source with a high and well-defined output power spectral density is provided which may be used for accurate calibration of Johnson Noise Power Thermometers (JNPT) and other applications requiring a stable, wide band, well-defined noise power spectral density. The noise source is based on the fact that the open-circuit thermal noise voltage of a feedback resistor, connecting the output to the input of a special inverting amplifier, is available at the amplifier output from an equivalent low output impedance caused by the feedback mechanism. The noise power spectral density level at the noise source output is equivalent to the density of the open-circuit thermal noise or a 100 ohm resistor at a temperature of approximately 64,000 Kelvins. The noise source has an output power spectral density that is flat to within 0.1% (0.0043 db) in the frequency range of from 1 KHz to 100 KHz which brackets typical passbands of the signal-processing channels of JNPT's. Two embodiments, one of higher accuracy that is suitable for use as a standards instrument and another that is particularly adapted for ambient temperature operation, are illustrated in this application

High level white noise generator

Science.gov (United States)

Borkowski, Casimer J.; Blalock, Theron V.

1979-01-01

A wide band, stable, random noise source with a high and well-defined output power spectral density is provided which may be used for accurate calibration of Johnson Noise Power Thermometers (JNPT) and other applications requiring a stable, wide band, well-defined noise power spectral density. The noise source is based on the fact that the open-circuit thermal noise voltage of a feedback resistor, connecting the output to the input of a special inverting amplifier, is available at the amplifier output from an equivalent low output impedance caused by the feedback mechanism. The noise power spectral density level at the noise source output is equivalent to the density of the open-circuit thermal noise or a 100 ohm resistor at a temperature of approximately 64,000 Kelvins. The noise source has an output power spectral density that is flat to within 0.1% (0.0043 db) in the frequency range of from 1 KHz to 100 KHz which brackets typical passbands of the signal-processing channels of JNPT's. Two embodiments, one of higher accuracy that is suitable for use as a standards instrument and another that is particularly adapted for ambient temperature operation, are illustrated in this application.

Antarctic ice sheet thickness estimation using the horizontal-to-vertical spectral ratio method with single-station seismic ambient noise

Directory of Open Access Journals (Sweden)

P. Yan

2018-03-01

Full Text Available We report on a successful application of the horizontal-to-vertical spectral ratio (H / V method, generally used to investigate the subsurface velocity structures of the shallow crust, to estimate the Antarctic ice sheet thickness for the first time. Using three-component, five-day long, seismic ambient noise records gathered from more than 60 temporary seismic stations located on the Antarctic ice sheet, the ice thickness measured at each station has comparable accuracy to the Bedmap2 database. Preliminary analysis revealed that 60 out of 65 seismic stations on the ice sheet obtained clear peak frequencies (f0 related to the ice sheet thickness in the H / V spectrum. Thus, assuming that the isotropic ice layer lies atop a high velocity half-space bedrock, the ice sheet thickness can be calculated by a simple approximation formula. About half of the calculated ice sheet thicknesses were consistent with the Bedmap2 ice thickness values. To further improve the reliability of ice thickness measurements, two-type models were built to fit the observed H / V spectrum through non-linear inversion. The two-type models represent the isotropic structures of single- and two-layer ice sheets, and the latter depicts the non-uniform, layered characteristics of the ice sheet widely distributed in Antarctica. The inversion results suggest that the ice thicknesses derived from the two-layer ice models were in good concurrence with the Bedmap2 ice thickness database, and that ice thickness differences between the two were within 300 m at almost all stations. Our results support previous finding that the Antarctic ice sheet is stratified. Extensive data processing indicates that the time length of seismic ambient noise records can be shortened to two hours for reliable ice sheet thickness estimation using the H / V method. This study extends the application fields of the H / V method and provides an effective and independent way to measure

Interaction of salicylate and noise results in mortality of rats.

Science.gov (United States)

Brennan, J F; Jastreboff, P J

1989-08-15

Survival as a function of salicylate dose and the intensity of environmental noise was investigated in 150 adult female pigmented rats. Rats were assigned to groups (n = 6/group) defined by combinations of salicylate levels from 0-(saline) to 300 mg/kg, injected subcutaneously, and noise levels from ambient noise to 98 dB SPL, presented daily for 10-h periods for up to 17 days. Mortality occurred in groups exposed to the higher combinations of salicylate and noise.

Obtaining and Estimating Low Noise Floors in Vibration Sensors

DEFF Research Database (Denmark)

Brincker, Rune; Larsen, Jesper Abildgaard

2007-01-01

For some applications like seismic applications and measuring ambient vibrations in structures, it is essential that the noise floors of the sensors and other system components are low and known to the user. Some of the most important noise sources are reviewed and it is discussed how the sensor...... can be designed in order to obtain a low noise floor. Techniques to estimate the noise floors for sensors are reviewed and are demonstrated on a commercial commonly used sensor for vibration testing. It is illustrated how the noise floor can be calculated using the coherence between simultaneous...

Upper and Middle Crustal Velocity Structure of the Colombian Andes From Ambient Noise Tomography: Investigating Subduction-Related Magmatism in the Overriding Plate

Science.gov (United States)

Poveda, Esteban; Julià, Jordi; Schimmel, Martin; Perez-Garcia, Nelson

2018-02-01

New maps of S velocity variation for the upper and middle crust making up the northwestern most corner of South America have been developed from cross correlation of ambient seismic noise at 52 broadband stations in the region. Over 1,300 empirical Green's functions, reconstructing the Rayleigh wave portion of the seismic wavefield, were obtained after time and frequency-domain normalization of the ambient noise recordings and stacking of 48 months of normalized data. Interstation phase and group velocity curves were then measured in the 6-38 s period range and tomographically inverted to produce maps of phase and group velocity variation in a 0.5° × 0.5° grid. Velocity-depth profiles were developed for each node after simultaneously inverting phase and group velocity curves and combined to produce 3-D maps of S velocity variation for the region. The S velocity models reveal a 7 km thick sedimentary cover in the Caribbean region, the Magdalena Valley, and the Cordillera Oriental, as well as crustal thicknesses in the Pacific and Caribbean region under 35 km, consistent with previous studies. They also display zones of slow velocity at 25-35 km depth under regions of both active and inactive volcanism, suggesting the presence of melts that carry the signature of segmented subduction into the overriding plate. A low-velocity zone in the same depth range is imaged under the Lower Magdalena Basin in the Caribbean region, which may represent either sublithospheric melts ponding at midcrustal levels after breaching through a fractured Caribbean flat slab or fluid migration through major faults within the Caribbean crust.

Time-lapse imaging of fault properties at seismogenic depth using repeating earthquakes, active sources and seismic ambient noise

Science.gov (United States)

Cheng, Xin

2009-12-01

The time-varying stress field of fault systems at seismogenic depths plays the mort important role in controlling the sequencing and nucleation of seismic events. Using seismic observations from repeating earthquakes, controlled active sources and seismic ambient noise, five studies at four different fault systems across North America, Central Japan, North and mid-West China are presented to describe our efforts to measure such time dependent structural properties. Repeating and similar earthquakes are hunted and analyzed to study the post-seismic fault relaxation at the aftershock zone of the 1984 M 6.8 western Nagano and the 1976 M 7.8 Tangshan earthquakes. The lack of observed repeating earthquakes at western Nagano is attributed to the absence of a well developed weak fault zone, suggesting that the fault damage zone has been almost completely healed. In contrast, the high percentage of similar and repeating events found at Tangshan suggest the existence of mature fault zones characterized by stable creep under steady tectonic loading. At the Parkfield region of the San Andreas Fault, repeating earthquake clusters and chemical explosions are used to construct a scatterer migration image based on the observation of systematic temporal variations in the seismic waveforms across the occurrence time of the 2004 M 6 Parkfield earthquake. Coseismic fluid charge or discharge in fractures caused by the Parkfield earthquake is used to explain the observed seismic scattering properties change at depth. In the same region, a controlled source cross-well experiment conducted at SAFOD pilot and main holes documents two large excursions in the travel time required for a shear wave to travel through the rock along a fixed pathway shortly before two rupture events, suggesting that they may be related to pre-rupture stress induced changes in crack properties. At central China, a tomographic inversion based on the theory of seismic ambient noise and coda wave interferometry

Ambient Noise Tomography at Regional and Local Scales in Southern California using Rayleigh Wave Phase Dispersion and Ellipticity

Science.gov (United States)

Berg, E.; Lin, F. C.; Qiu, H.; Wang, Y.; Allam, A. A.; Clayton, R. W.; Ben-Zion, Y.

2017-12-01

Rayleigh waves extracted from cross-correlations of ambient seismic noise have proven useful in imaging the shallow subsurface velocity structure. In contrast to phase velocities, which are sensitive to slightly deeper structure, Rayleigh wave ellipticity (H/V ratios) constrains the uppermost crust. We conduct Rayleigh wave ellipticity and phase dispersion measurements in Southern California between 6 and 18 second periods, computed from multi-component ambient noise cross-correlations using 315 stations across the region in 2015. Because of the complimentary sensitivity of phase velocity and H/V, this method enables simple and accurate resolution of near-surface geological features from the surface to 20km depth. We compare the observed H/V ratios and phase velocities to predictions generated from the current regional models (SCEC UCVM), finding strong correspondence where the near-surface structure is well-resolved by the models. This includes high H/V ratios in the LA Basin, Santa Barbara Basin and Salton Trough; and low ratios in the San Gabriel, San Jacinto and southern Sierra Nevada mountains. Disagreements in regions such as the Western Transverse Ranges, Salton Trough, San Jacinto and Elsinore fault zones motivate further work to improve the community models. A new updated 3D isotropic model of the area is derived via a joint inversion of Rayleigh phase dispersions and H/V ratios. Additionally, we examine azimuthal dependence of the H/V ratio to ascertain anisotropy patterns for each station. Clear 180º periodicity is observed for many stations suggesting strong shallow anisotropy across the region including up to 20% along the San Andreas fault, 15% along the San Jacinto Fault and 25% in the LA Basin. To better resolve basin structures, we apply similar techniques to three dense linear geophone arrays in the San Gabriel and San Bernardino basins. The three arrays are composed by 50-125 three-component 5Hz geophones deployed for one month each with 15-25km

Noise detection during heart sound recording using periodicity signatures

International Nuclear Information System (INIS)

Kumar, D; Carvalho, P; Paiva, R P; Henriques, J; Antunes, M

2011-01-01

Heart sound is a valuable biosignal for diagnosis of a large set of cardiac diseases. Ambient and physiological noise interference is one of the most usual and highly probable incidents during heart sound acquisition. It tends to change the morphological characteristics of heart sound that may carry important information for heart disease diagnosis. In this paper, we propose a new method applicable in real time to detect ambient and internal body noises manifested in heart sound during acquisition. The algorithm is developed on the basis of the periodic nature of heart sounds and physiologically inspired criteria. A small segment of uncontaminated heart sound exhibiting periodicity in time as well as in the time-frequency domain is first detected and applied as a reference signal in discriminating noise from the sound. The proposed technique has been tested with a database of heart sounds collected from 71 subjects with several types of heart disease inducing several noises during recording. The achieved average sensitivity and specificity are 95.88% and 97.56%, respectively

A rapid prototyping system for broadband multichannel active noise and vibration control

NARCIS (Netherlands)

Wesselink, J.M.

2009-01-01

In recent years the need for active and passive noise reduction methods has increased. This is due to an increase in the ambient noise caused by industrialization and the extended use of power tools. The effects of noise on a person can be quite severe and can cause illness and in severe cased lead

Qademah Fault Artificial Ambient Noise Test

KAUST Repository

Hanafy, Sherif M.

2014-01-01

This data set was collected on 7 Dec. 2014 by Sherif and Abdullah. The receiver layout is the same as that of the passive data test at the same location, which is described as follow: 288 receivers are used and arranged as follow - 12 lines, cross-line offset = 10 m - 24 receiver in each line, inline offset = 5 m - Additional 24 receivers are placed at line # 6, where the receiver interval is decreased to 2.5 m. Data Recording: We start recording at 10:10 am and stop recording at 11:25 am. Each record has total of 20 s, with time interval of 0.004 ms and around 2 s overlap between each two successive files. Source: We used a piece of wood attached to a pick-up truck to create the noise; we drove around the array of receivers in a rectangle-shape route during the recording time.

Noise-Induced Hearing Loss – A Preventable Disease? Results of a 10-Year Longitudinal Study of Workers Exposed to Occupational Noise

Science.gov (United States)

Frederiksen, Thomas W.; Ramlau-Hansen, Cecilia H.; Stokholm, Zara A.; Grynderup, Matias B.; Hansen, Åse M.; Kristiansen, Jesper; Vestergaard, Jesper M.; Bonde, Jens P.; Kolstad, Henrik A.

2017-01-01

Aims: To survey current, Danish industrial noise levels and the use of hearing protection devices (HPD) over a 10-year period and to characterise the association between occupational noise and hearing threshold shift in the same period. Furthermore, the risk of hearing loss among the baseline and the follow-up populations according to first year of occupational noise exposure is evaluated. Materials and Methods: In 2001–2003, we conducted a baseline survey of noise- and hearing-related disorders in 11 industries with suspected high noise levels. In 2009–2010, we were able to follow up on 271 out of the 554 baseline workers (49%). Mean noise levels per industry and self-reported HPD use are described at baseline and follow-up. The association between cumulative occupational noise exposure and hearing threshold shift over the 10-year period was assessed using linear regression, and the risk of hearing loss according to year of first occupational noise exposure was evaluated with logistic regression. Results: Over the 10-year period, mean noise levels declined from 83.9 dB(A) to 82.8 dB(A), and for workers exposed >85 dB(A), the use of HPD increased from 70.1 to 76.1%. We found a weak, statistically insignificant, inverse association between higher ambient cumulative noise exposure and poorer hearing (−0.10 dB hearing threshold shift per dB-year (95% confidence interval (CI): −0.36; 0.16)). The risk of hearing loss seemed to increase with earlier first year of noise exposure, but odds ratios were only statistically significant among baseline participants with first exposure before the 1980s (odds ratio: 1.90, 95% CI: 1.11; 3.22). Conclusions: We observed declining industrial noise levels, increased use of HPD and no significant impact on hearing thresholds from current ambient industrial noise levels, which indicated a successful implementation of Danish hearing conservation programs. PMID:29192620

Noise-Induced Hearing Loss – A Preventable Disease? Results of a 10-Year Longitudinal Study of Workers Exposed to Occupational Noise

Directory of Open Access Journals (Sweden)

Thomas W Frederiksen

2017-01-01

Full Text Available Aims: To survey current, Danish industrial noise levels and the use of hearing protection devices (HPD over a 10-year period and to characterise the association between occupational noise and hearing threshold shift in the same period. Furthermore, the risk of hearing loss among the baseline and the follow-up populations according to first year of occupational noise exposure is evaluated. Materials and Methods: In 2001–2003, we conducted a baseline survey of noise- and hearing-related disorders in 11 industries with suspected high noise levels. In 2009–2010, we were able to follow up on 271 out of the 554 baseline workers (49%. Mean noise levels per industry and self-reported HPD use are described at baseline and follow-up. The association between cumulative occupational noise exposure and hearing threshold shift over the 10-year period was assessed using linear regression, and the risk of hearing loss according to year of first occupational noise exposure was evaluated with logistic regression. Results: Over the 10-year period, mean noise levels declined from 83.9 dB(A to 82.8 dB(A, and for workers exposed >85 dB(A, the use of HPD increased from 70.1 to 76.1%. We found a weak, statistically insignificant, inverse association between higher ambient cumulative noise exposure and poorer hearing (−0.10 dB hearing threshold shift per dB-year (95% confidence interval (CI: −0.36; 0.16. The risk of hearing loss seemed to increase with earlier first year of noise exposure, but odds ratios were only statistically significant among baseline participants with first exposure before the 1980s (odds ratio: 1.90, 95% CI: 1.11; 3.22. Conclusions: We observed declining industrial noise levels, increased use of HPD and no significant impact on hearing thresholds from current ambient industrial noise levels, which indicated a successful implementation of Danish hearing conservation programs.

Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight, so ambient light will increase the noise and may even damage them.

CERN Multimedia

Nooren, G.

2004-01-01

Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight , so ambient light will increase the noise and may even damage them.

Stationary-phase integrals in the cross correlation of ambient noise

NARCIS (Netherlands)

Boschi, L.; Weemstra, C.

2015-01-01

The cross correlation of ambient signal allows seismologists to collect data even in the absence of seismic events. “Seismic interferometry” shows that the cross correlation of simultaneous recordings of a random wavefield made at two locations is formally related to the impulse response between

Speech perception in noise in unilateral hearing loss

OpenAIRE

Mondelli, Maria Fernanda Capoani Garcia; dos Santos, Marina de Marchi; José, Maria Renata

2016-01-01

ABSTRACT INTRODUCTION: Unilateral hearing loss is characterized by a decrease of hearing in one ear only. In the presence of ambient noise, individuals with unilateral hearing loss are faced with greater difficulties understanding speech than normal listeners. OBJECTIVE: To evaluate the speech perception of individuals with unilateral hearing loss in speech perception with and without competitive noise, before and after the hearing aid fitting process. METHODS: The study included 30 adu...

Occupational noise exposure and noise-induced hearing loss are associated with work-related injuries leading to admission to hospital.

Science.gov (United States)

Girard, Serge-André; Leroux, Tony; Courteau, Marilene; Picard, Michel; Turcotte, Fernand; Richer, Olivier

2015-04-01

This study focuses on work-related injuries that required admission to hospital in a population of male workers exposed to occupational noise (≥80 dBA) which some displayed a hearing loss due to their exposure. The study population count 46 550 male workers, 1670 (3.6%) of whom incurred at least one work-related injury requiring admission to hospital within a period of 5 years following hearing tests conducted between 1987 and 2005. The noise exposure and hearing loss-related data were gathered during occupational noise-induced hearing loss (NIHL) screening. The hospital data were used to identify all members of the study population who were admitted, and the reason for admission. Finally, access to the death-related data made it possible to identify participants who died during the course of the study. Cox proportional hazards model taking into account hearing status, noise levels, age and cumulative duration of noise exposure at the time of the hearing test established the risk of work-related injuries leading to admission to hospital. For each dB of hearing loss, a statistically significant risk increase was observed (HR=1.01 dB 95% CI 1.006 to 1.01). An association (HR=2.36 95% CI 2.01 to 2.77) was also found between working in an occupational ambient noise ≥100 dBA and the risk of injury. From a safety perspective, this issue is highly relevant; especially when workers are exposed to intense ambient noise and NIHL. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Ambient Field Analysis at Groningen Gas Field

Science.gov (United States)

Spica, Z.; Nakata, N.; Beroza, G. C.

2016-12-01

We analyze continuous ambient-field data at Groningen gas field (Netherlands) through cross-correlation processing. The Groningen array is composed of 75 shallow boreholes with 6 km spacing, which contain a 3C surface accelerometer and four 5-Hz 3C borehole geophones spaced at 50 m depth intervals. We successfully retrieve coherent waves from ambient seismic field on the 9 components between stations. Results show high SNR signal in the frequency range of 0.125-1 Hz, and the ZZ, ZR, RZ, RR and TT components show much stronger wave energy than other components as expected. This poster discuss the different type of waves retrieved, the utility of the combination of borehole and surface observations, future development as well as the importance to compute the 9 components of the Green's tensor to better understand the wave field propriety with ambient noise.

Crustal imaging of western Michoacán and the Jalisco Block, Mexico, from Ambient Seismic Noise

Science.gov (United States)

Spica, Zack; Cruz-Atienza, Víctor M.; Reyes-Alfaro, Gabriel; Legrand, Denis; Iglesias-Mendoza, Arturo

2014-12-01

Detailed crustal imaging of western Michoacán and the Jalisco Block is obtained from ambient noise tomography. Results show a deep and well-delineated volcanic system below the Colima volcano complex, rooting up to ~ 22 km depth, with a shallow magmatic chamber constrained to the first ~ 7 km. A shallow low-velocity system to the south of the Chapala rift and west of the Michoacán-Guanajuato volcanic field merges, underneath the Colima rift, with the Colima volcano system at about 20 km depth, honoring the geometry of the Trans-Mexican Volcanic Belt. For depths greater than ~30 km, low-velocity features become parallel to the slab strike, right beneath the Mascota, Ayutla and Tapalpa volcanic fields, suggesting the presence of the mantle wedge above the Rivera plate. All mentioned low-velocity bodies are spatially correlated with the superficial volcanic activity suggesting their magmatic origin so that, the shallower these bodies, the younger are the associated volcanic deposits. Along the coast, different depths of the uppermost layer of the Rivera and the Cocos plates suggest that the latter plate subducts with an angle ~ 9° steeper than the former.

On the attenuation of the ambient seismic field

International Nuclear Information System (INIS)

Weemstra, C.

2013-01-01

Although myriad applications exploiting the ambient seismic field have been reported to date, comparatively little attention has been paid to its potential to resolve subsurface attenuation. The ambient seismic field, however, may ultimately prove itself an invaluable asset in constraining subsurface attenuation structure. Especially areas with dense seismometer coverage hold great potential. Moreover, since this coverage continues to grow, significant developments may await in the future. Subsurface structure in terms of attenuation is of great importance for many reasons. For example, knowledge of the attenuation structure may aid in predicting ground motions caused by future large earthquakes. From a scientific perspective, a great deal of new information may be extracted, potentially fostering research in related fields (e.g., geodynamics, hydrology). Both from an environmental and economic point of view, inversion of the ambient seismic wavefield for attenuation structure may in the future provide a means to image hydrocarbon reservoirs. In sufficiently diffuse wavefields, simple cross-correlation of long noise time series recorded by two receivers results in the response at one of the receivers as if there was a source at the position of the other. I present a case study that shows that thus retrieved surface waves can be used to recover attenuation beneath an array of ocean-bottom seismometers. Given the small aperture of the seismic survey, this is unprecedented. Unambiguous interpretation of recovered attenuation values is of major importance. Lack of understanding of the effect that preprocessing has on the amplitude of the noise cross-correlation prevents such unambiguous interpretation. I carefully examine the effect spectral whitening has on the noise cross-correlation. Emphasis is given to the dependence of the amplitudes on the length of the time windows employed in the cross-correlation procedure. Short time-window lengths may require an additional

Anatomy of the high-frequency ambient seismic wave field at the TCDP borehole.

OpenAIRE

Hillers , Gregor; Campillo , Michel; Lin , Y.-Y.; Ma , K.F.; Roux , Philippe

2012-01-01

International audience; The Taiwan Chelungpu-fault Drilling Project (TCDP) installed a vertical seismic array between 950 and 1270 m depth in an active thrust fault environment. In this paper we analyze continuous noise records of the TCDP array between 1 and 16 Hz. We apply multiple array processing and noise correlation techniques to study the noise source process, properties of the propagation medium, and the ambient seismic wave field. Diurnal amplitude and slowness patterns suggest that ...

A descriptive study of noise in the neonatal intensive care unit: ambient levels and perceptions of contributing factors.

Science.gov (United States)

Darcy, Ashley E; Hancock, Lauren E; Ware, Emily J

2008-10-01

To examine the baseline acoustic environment in several mid-Atlantic region neonatal intensive care units (NICUs) and investigate the perceived factors contributing to noise levels in these NICUs. Quantitative data were collected from 3 urban, mid-Atlantic level IIIB and level IIIC NICUs. Qualitative data were collected via interview from 2 RNs employed in each of the study NICUs. This was an exploratory descriptive study utilizing a mixed-methods approach. A quantitative method was used for sound-level data collection, and a qualitative method was utilized during interviews with nurses to examine perceptions of factors contributing to noise. Ambient sound levels, measured in decibels, were taken at 5-minute intervals over a 2-hour period during both day and night shifts in a central location at each NICU. In addition, nurses were interviewed using a standardized interview questionnaire, and these interviews were then reviewed to determine themes regarding perceived factors contributing to sound levels. Hourly mean sound levels in each NICU ranged from 53.9 dB to 60.6 dB, with no statistically significant difference between noise levels recorded on day shift versus night shift, and no statistically significant difference among sites. Qualitative data showed that nurses' believed day shift to be louder than night shift and many perceived their own NICU as "pretty quiet." Key contributing factors to increased sound levels were stated as monitors or alarms, performing invasive procedures, presence of family, nurses or doctors giving report or rounds, and ringing phones. Noise levels were found to be above the American Academy of Pediatrics-recommended 45-dB level and often louder than the 50-dB level, which should not be exceeded more than 10% of the time. The recommended impulse maximum of 65 dB was also exceeded. Environmental Protection Agency recommendations for hospitals include sound levels no louder than 35 dB on night shift; this standard was also violated

A descriptive study of noise in the neonatal intensive care unit. Ambient levels and perceptions of contributing factors.

Science.gov (United States)

Darcy, Ashley E; Hancock, Lauren E; Ware, Emily J

2008-06-01

To examine the baseline acoustic environment in several mid-Atlantic region neonatal intensive care units (NICUs) and investigate the perceived factors contributing to noise levels in these NICUs. Quantitative data were collected from 3 urban, mid-Atlantic level IIIB and level IIIC NICUs. Qualitative data were collected via interview from 2 RNs employed in each of the study NICUs. This was an exploratory descriptive study utilizing a mixed-methods approach. A quantitative method was used for sound-level data collection, and a qualitative method was utilized during interviews with nurses to examine perceptions of factors contributing to noise. Ambient sound levels, measured in decibels, were taken at 5-minute intervals over a 2-hour period during both day and night shifts in a central location at each NICU. In addition, nurses were interviewed using a standardized interview questionnaire, and these interviews were then reviewed to determine themes regarding perceived factors contributing to sound levels. Hourly mean sound levels in each NICU ranged from 53.9 dB to 60.6 dB, with no statistically significant difference between noise levels recorded on day shift versus night shift, and no statistically significant difference among sites. Qualitative data showed that nurses' believed day shift to be louder than night shift and many perceived their own NICU as "pretty quiet." Key contributing factors to increased sound levels were stated as monitors or alarms, performing invasive procedures, presence of family, nurses or doctors giving report or rounds, and ringing phones. Noise levels were found to be above the American Academy of Pediatrics--recommended 45-dB level and often louder than the 50-dB level, which should not be exceeded more than 10% of the time. The recommended impulse maximum of 65 dB was also exceeded. Environmental Protection Agency recommendations for hospitals include sound levels no louder than 35 dB on night shift; this standard was also violated

A novel method for the evaluation of polarization and hemisphere coverage of HF radio noise measurement antennas

NARCIS (Netherlands)

Witvliet, Ben A.; van Maanen, Erik; Bentum, Mark J.; Slump, Cornelis H.; Schiphorst, Roel

2015-01-01

In HF (3-30 MHz) communications the ambient electromagnetic background noise or 'radio noise' generally is the limiting factor in reception. Radio noise measurements are needed for spectrum pollution control and to provide reference levels for radio system design. This article discusses the

High resolution Rayleigh wave group velocity tomography in North-China from ambient seismic noise

International Nuclear Information System (INIS)

Fang Lihua; Wu Jianping; Ding Zhifeng; Panza, G.F.

2009-03-01

This study presents the results of the Rayleigh wave group velocity tomography in North-China performed using ambient seismic noise observed at 190 broadband and 10 very broadband stations of the North-China Seismic Array. All available vertical component time-series for the 14 months span between January, 2007 and February, 2008 are cross-correlated to obtain empirical Rayleigh wave Green functions that are subsequently processed, with the multiple filter method, to isolate the group velocity dispersion curves of the fundamental mode of Rayleigh wave. Tomographic maps, with a grid spacing of 0.25 deg. x 0.25 deg., are computed at the periods of 4.5s, 12s, 20s, 28s. The maps at short periods reveal an evident lateral heterogeneity in the crust of North-China, quite well in agreement with known geological and tectonic features. The North China Basin is imaged as a broad low velocity area, while the Taihangshan and Yanshan uplifts and Ordos block are imaged as high velocity zones, and the Quaternary intermountain basins show up as small low-velocity anomalies. The group velocity contours at 4.5s, 12s and 20s are consistent with the Bouguer gravity anomalies measured in the area of the Taihangshan fault, that cuts through the lower crust at least. Most of the historical strong earthquakes (M≥6.0) are located where the tomographic maps show zones with moderate velocity gradient. (author)

Shallow velocity structure above the Socorro Magma Body from ambient noise tomography using the large-N Sevilleta array, central Rio Grande Rift, New Mexico

Science.gov (United States)

Worthington, L. L.; Ranasinghe, N. R.; Schmandt, B.; Jiang, C.; Finlay, T. S.; Bilek, S. L.; Aster, R. C.

2017-12-01

The Socorro Magma Body (SMB) is one of the largest recognized active mid-crustal magma intrusions globally. Inflation of the SMB drives sporadically seismogenic uplift at rates of up to of few millimeters per year. We examine the upper crustal structure of the northern section of the SMB region using ambient noise seismic data collected from the Sevilleta Array and New Mexico Tech (NMT) seismic network to constrain basin structure and identify possible upper crustal heterogeneities caused by heat flow and/or fluid or magma migration to shallower depths. The Sevilleta Array comprised 801 vertical-component Nodal seismic stations with 10-Hz seismometers deployed within the Sevilleta National Wildlife Refuge in the central Rio Grande rift north of Socorro, New Mexico, for a period of 12 days during February 2015. Five short period seismic stations from the NMT network located south of the Sevilleta array are also used to improve the raypath coverage outside the Sevilleta array. Inter-station ambient noise cross-correlations were computed from all available 20-minute time windows and stacked to obtain estimates of the vertical component Green's function. Clear fundamental mode Rayleigh wave energy is observed from 3 to 6 s period. Beamforming indicates prominent noise sources from the southwest, near Baja California, and the southeast, in the Gulf of Mexico. The frequency-time analysis method was implemented to measure fundamental mode Rayleigh wave phase velocities and the resulting inter-station travel times were inverted to obtain 2-D phase velocity maps. One-dimensional sensitivity kernels indicate that the Rayleigh wave phase velocity maps are sensitive to a depth interval of 1 to 8 km, depending on wave period. The maps show (up to 40%) variations in phase velocity within the Sevilleta Array, with the largest variations found for periods of 5-6 seconds. Holocene to upper Pleistocene, alluvial sediments found in the Socorro Basin consistently show lower phase

Assessment of ambient noise levels in the intensive care unit of a university hospital

Directory of Open Access Journals (Sweden)

Hatem O Qutub

2009-01-01

Conclusion : Some sources of environmental noise, such as the use of oxygen, suction equipment or respirators are unavoidable. Nevertheless, hospital ICUs should have measures to minimize the level of exposure to noise in the ICU. Further research in this area might focus on the noise level and other modifiable environmental stress factors in the ICU that affect patients as well as the staff.

Newtonian noise cancellation in tensor gravitational wave detector

International Nuclear Information System (INIS)

Paik, Ho Jung; Harms, Jan

2016-01-01

Terrestrial gravity noise produced by ambient seismic and infrasound fields poses one of the main sensitivity limitations in low-frequency ground-based gravitational-wave (GW) detectors. This noise needs to be suppressed by 3-5 orders of magnitude in the frequency band 10 mHz to 1 Hz, which is extremely challenging. We present a new approach that greatly facilitates cancellation of gravity noise in full-tensor GW detectors. It makes explicit use of the direction of propagation of a GW, and can therefore either be implemented in directional searches for GWs or in observations of known sources. We show that suppression of the Newtonian-noise foreground is greatly facilitated using the extra strain channels in full-tensor GW detectors. Only a modest number of auxiliary, high-sensitivity environmental sensors is required to achieve noise suppression by a few orders of magnitude. (paper)

Single-photoelectron noise reduction in scintillation detectors

International Nuclear Information System (INIS)

Marvin, T.P.

1995-10-01

The 1994--95 search at SLAC for mulicharged particles used four 21 x 21 x 130-cm 3 Bicron 408 scintillation counters to detect a signal at the single-photoelectron level. The competing noise requiring minimization was due to a combination of PM tube (8-inch Thorne EMI 9353KA) afterpulsing and ambient radiation-induced scintillator luminescence. A very slow decay (> 30 μs) component was observed and received particular attention. Efforts to reduce the SPE noise included photomultiplier tube base modifications, detector shielding and cooling, signal amplification, and veto procedures

Anthropogenic noise pollution from pile-driving disrupts the structure and dynamics of fish shoals.

Science.gov (United States)

Herbert-Read, James E; Kremer, Louise; Bruintjes, Rick; Radford, Andrew N; Ioannou, Christos C

2017-09-27

Noise produced from a variety of human activities can affect the physiology and behaviour of individual animals, but whether noise disrupts the social behaviour of animals is largely unknown. Animal groups such as flocks of birds or shoals of fish use simple interaction rules to coordinate their movements with near neighbours. In turn, this coordination allows individuals to gain the benefits of group living such as reduced predation risk and social information exchange. Noise could change how individuals interact in groups if noise is perceived as a threat, or if it masked, distracted or stressed individuals, and this could have impacts on the benefits of grouping. Here, we recorded trajectories of individual juvenile seabass ( Dicentrarchus labrax ) in groups under controlled laboratory conditions. Groups were exposed to playbacks of either ambient background sound recorded in their natural habitat, or playbacks of pile-driving, commonly used in marine construction. The pile-driving playback affected the structure and dynamics of the fish shoals significantly more than the ambient-sound playback. Compared to the ambient-sound playback, groups experiencing the pile-driving playback became less cohesive, less directionally ordered, and were less correlated in speed and directional changes. In effect, the additional-noise treatment disrupted the abilities of individuals to coordinate their movements with one another. Our work highlights the potential for noise pollution from pile-driving to disrupt the collective dynamics of fish shoals, which could have implications for the functional benefits of a group's collective behaviour. © 2017 The Authors.

LTP interferometer-noise sources and performance

International Nuclear Information System (INIS)

Robertson, David; Killow, Christian; Ward, Harry; Hough, Jim; Heinzel, Gerhard; Garcia, Antonio; Wand, Vinzenz; Johann, Ulrich; Braxmaier, Claus

2005-01-01

The LISA Technology Package (LTP) uses laser interferometry to measure the changes in relative displacement between two inertial test masses. The goals of the mission require a displacement measuring precision of 10 pm Hz -1/2 at frequencies in the 3-30 mHz band. We report on progress with a prototype LTP interferometer optical bench in which fused silica mirrors and beamsplitters are fixed to a ZERODUR (registered) substrate using hydroxide catalysis bonding to form a rigid interferometer. The couplings to displacement noise of this interferometer of two expected noise sources-laser frequency noise and ambient temperature fluctuations-have been investigated, and an additional, unexpected, noise source has been identified. The additional noise is due to small amounts of signal at the heterodyne frequency arriving at the photodiode preamplifiers with a phase that quasistatically changes with respect to the optical signal. The phase shift is caused by differential changes in the external optical paths the beams travel before they reach the rigid interferometer. Two different external path length stabilization systems have been demonstrated and these allowed the performance of the overall system to meet the LTP displacement noise requirement

Application of the Spatial Auto-Correlation Method for Shear-Wave Velocity Studies Using Ambient Noise

Science.gov (United States)

Asten, M. W.; Hayashi, K.

2018-05-01

Ambient seismic noise or microtremor observations used in spatial auto-correlation (SPAC) array methods consist of a wide frequency range of surface waves from the frequency of about 0.1 Hz to several tens of Hz. The wavelengths (and hence depth sensitivity of such surface waves) allow determination of the site S-wave velocity model from a depth of 1 or 2 m down to a maximum of several kilometres; it is a passive seismic method using only ambient noise as the energy source. Application usually uses a 2D seismic array with a small number of seismometers (generally between 2 and 15) to estimate the phase velocity dispersion curve and hence the S-wave velocity depth profile for the site. A large number of methods have been proposed and used to estimate the dispersion curve; SPAC is the one of the oldest and the most commonly used methods due to its versatility and minimal instrumentation requirements. We show that direct fitting of observed and model SPAC spectra generally gives a superior bandwidth of useable data than does the more common approach of inversion after the intermediate step of constructing an observed dispersion curve. Current case histories demonstrate the method with a range of array types including two-station arrays, L-shaped multi-station arrays, triangular and circular arrays. Array sizes from a few metres to several-km in diameter have been successfully deployed in sites ranging from downtown urban settings to rural and remote desert sites. A fundamental requirement of the method is the ability to average wave propagation over a range of azimuths; this can be achieved with either or both of the wave sources being widely distributed in azimuth, and the use of a 2D array sampling the wave field over a range of azimuths. Several variants of the method extend its applicability to under-sampled data from sparse arrays, the complexity of multiple-mode propagation of energy, and the problem of precise estimation where array geometry departs from an

Surface wave tomography across the Sorgenfrei-Tornquist Zone, SW Scandinavia, using ambient noise and earthquake data

Science.gov (United States)

Köhler, Andreas; Maupin, Valérie; Balling, Niels

2015-10-01

We produce a S-wave velocity model of the crust and upper mantle around the Sorgenfrei-Tornquist Zone, southern Scandinavia, by analysing ambient seismic noise and earthquake recordings on temporary and permanent regional network stations. In a first step, we perform tomographical inversion of surface wave dispersion data from seismic noise to obtain Rayleigh and Love wave phase-velocity maps from 3 to about 30 s period. Local dispersion curves are then combined with regionally averaged surface wave velocities from earthquake data measured between 15 and about 100 s period. Dispersion curves are jointly inverted for a 3-D model of the S-wave velocity and radial velocity anisotropy by using a combined Monte Carlo and linearized inversion approach. Results reveal significant crustal as well as uppermost mantle velocity variations at all depth levels. Upper crustal structural variations are mainly controlled by the thick sedimentary Danish Basin with both low S-wave velocities and high anisotropy. Despite of the known limited capability of surface wave inversion to constrain interface depths and model parameter trade-offs, obtained Moho depths are in good agreement with previous studies in the region. Marked crustal thinning is clearly revealed beneath the Danish Basin with a narrow transition to the thicker crust in Swedish shield areas. Despite very different crustal and morphological structures, Denmark and southern Norway both have similar well-defined upper-mantle low-velocity zones, interpreted as asthenosphere, starting a depth of about 100 km. Compared with southern Sweden, showing high upper-mantle velocities, characteristic for shields, velocities are reduced by 0.30-0.40 km s-1 (6-8 per cent) at the depth levels of 140-200 km and radial anisotropy of 2-4 per cent is observed. Our study confirms the importance of the Sorgenfrei-Tornquist Zone, as a very deep structural boundary, separating old, thick, cratonic Baltica lithosphere in southern Sweden from

Effect of long-term outdoor air pollution and noise on cognitive and psychological functions in adults.

Science.gov (United States)

Tzivian, Lilian; Winkler, Angela; Dlugaj, Martha; Schikowski, Tamara; Vossoughi, Mohammad; Fuks, Kateryna; Weinmayr, Gudrun; Hoffmann, Barbara

2015-01-01

It has been hypothesized that air pollution and ambient noise might impact neurocognitive function. Early studies mostly investigated the associations of air pollution and ambient noise exposure with cognitive development in children. More recently, several studies investigating associations with neurocognitive function, mood disorders, and neurodegenerative disease in adult populations were published, yielding inconsistent results. The purpose of this review is to summarize the current evidence on air pollution and noise effects on mental health in adults. We included studies in adult populations (≥18 years old) published in English language in peer-reviewed journals. Fifteen articles related to long-term effects of air pollution and eight articles on long-term effects of ambient noise were extracted. Both exposures were separately shown to be associated with one or several measures of global cognitive function, verbal and nonverbal learning and memory, activities of daily living, depressive symptoms, elevated anxiety, and nuisance. No study considered both exposures simultaneously and few studies investigated progression of neurocognitive decline or psychological factors. The existing evidence generally supports associations of environmental factors with mental health, but does not suffice for an overall conclusion about the independent effect of air pollution and noise. There is a need for studies investigating simultaneously air pollution and noise exposures in association mental health, for longitudinal studies to corroborate findings from cross-sectional analyses, and for parallel toxicological and epidemiological studies to elucidate mechanisms and pathways of action. Copyright © 2014 Elsevier GmbH. All rights reserved.

Study on Noise Prediction Model and Control Schemes for Substation

Science.gov (United States)

Gao, Yang; Liu, Songtao

2014-01-01

With the government's emphasis on environmental issues of power transmission and transformation project, noise pollution has become a prominent problem now. The noise from the working transformer, reactor, and other electrical equipment in the substation will bring negative effect to the ambient environment. This paper focuses on using acoustic software for the simulation and calculation method to control substation noise. According to the characteristics of the substation noise and the techniques of noise reduction, a substation's acoustic field model was established with the SoundPLAN software to predict the scope of substation noise. On this basis, 4 reasonable noise control schemes were advanced to provide some helpful references for noise control during the new substation's design and construction process. And the feasibility and application effect of these control schemes can be verified by using the method of simulation modeling. The simulation results show that the substation always has the problem of excessive noise at boundary under the conventional measures. The excess noise can be efficiently reduced by taking the corresponding noise reduction methods. PMID:24672356

South Ilan Plain High-Resolution 3-D S-Wave Velocity from Ambient Noise Tomography

Directory of Open Access Journals (Sweden)

Kai-Xun Chen

2016-06-01

Full Text Available The Ilan Plain in northeastern Taiwan is located at a pivotal point where the Ryukyu trench subduction zone, the northern Taiwan crustal stretching zone, and the ongoing arc-continent collision zone converge. In contrast to the North Ilan Plain, the South Ilan Plain exhibits a thin unconsolidated sedimentary layer with depths ranging from 0 - 1 km, high on-land seismicity and significant SE movements relative to Penghu island. We deployed a dense network of 43 short-period vertical component Texan instruments from June to November 2013 in this study, covering most of the South Ilan Plain and its vicinity. We then used the ambient noise tomography method for simultaneous phase and group Rayleigh wave velocity measurements to invert a high-resolution 3-D S-wave for shallow structures (up to a depth of 2.5 km in the South Ilan Plain. We used the fast marching method for ray tracing to deal with ray bending in an inhomogeneous medium. The resulting rays gradually bend toward high velocity zones with increasing number of iterations. The high velocity zone results are modified by more iterations and the resolutions become higher because ray crossings are proportional to ray densities for evenly distributed stations. The final results agreed well with known sedimentary basement thickness patterns. We observed nearly EW trending fast anomalies beneath the mountainous terrain abutting to the South Ilan Plain. The Chingshui location consistently exhibited a low S-wave velocity zone to a depth of 1.5 km.

Coherent ambient infrasound recorded by the global IMS network

Science.gov (United States)

Matoza, R. S.; Landes, M.; Le Pichon, A.; Ceranna, L.; Brown, D.

2011-12-01

The International Monitoring System (IMS) includes a global network of infrasound arrays, which is designed to detect atmospheric nuclear explosions anywhere on the planet. The infrasound network also has potential application in detection of natural hazards such as large volcanic explosions and severe weather. Ambient noise recorded by the network includes incoherent wind noise and coherent infrasound. We present a statistical analysis of coherent infrasound recorded by the IMS network. We have applied broadband (0.01 to 5 Hz) array processing systematically to the multi-year IMS historical dataset (2005-present) using an implementation of the Progressive Multi-Channel Correlation (PMCC) algorithm in log-frequency space. We show that IMS arrays consistently record coherent ambient infrasound across the broad frequency range from 0.01 to 5 Hz when wind-noise levels permit. Multi-year averaging of PMCC detection bulletins emphasizes continuous signals such as oceanic microbaroms, as well as persistent transient signals such as repetitive volcanic, surf, or anthropogenic activity (e.g., mining or industrial activity). While many of these continuous or repetitive signals are of interest in their own right, they may dominate IMS array detection bulletins and obscure or complicate detection of specific signals of interest. The new PMCC detection bulletins have numerous further applications, including in volcano and microbarom studies, and in IMS data quality assessment.

Monitoring Unstable Glaciers with Seismic Noise Interferometry

Science.gov (United States)

Preiswerk, L. E.; Walter, F.

2016-12-01

Gravity-driven glacier instabilities are a threat to human infrastructure in alpine terrain, and this hazard is likely to increase with future changes in climate. Seismometers have been used previously on hazardous glaciers to monitor the natural englacial seismicity. In some situations, an increase in "icequake" activity may indicate fracture growth and thus an imminent major break-off. However, without independent constraints on unstable volumes, such mere event counting is of little use. A promising new approach to monitor unstable masses in Alpine terrain is coda wave interferometry of ambient noise. While already established in the solid earth, application to glaciers is not straightforward, because the lack of inhomogeneities typically suppresses seismic coda waves in glacier ice. Only glaciers with pervasive crevasses provide enough scattering to generate long codas. This is requirement is likely met for highly dynamic unstable glaciers. Here, we report preliminary results from a temporary 5-station on-ice array of seismometers (corner frequencies: 1 Hz, array aperture: 500m) on Bisgletscher (Switzerland). The seismometers were deployed in shallow boreholes, directly above the unstable tongue of the glacier. In the frequency band 4-12 Hz, we find stable noise cross-correlations, which in principle allows monitoring on a subdaily scale. The origin and the source processes of the ambient noise in these frequencies are however uncertain. As a first step, we evaluate the stability of the sources in order to separate effects of changing source parameters from changes of englacial properties. Since icequakes occurring every few seconds may dominate the noise field, we compare their temporal and spatial occurrences with the cross-correlation functions (stability over time, the asymmetry between causal and acausal parts of the cross-correlation functions) as well as with results from beamforming to assess the influence of these transient events on the noise field.

Mirror Symmetry Breaking and Restoration: The Role of Noise and Chiral Bias

International Nuclear Information System (INIS)

Hochberg, David

2009-01-01

The nonequilibrium effective potential is computed for the Frank model of spontaneous mirror symmetry breaking (SMSB) in chemistry in which external noise is introduced to account for random environmental effects. When these fluctuations exceed a critical magnitude, mirror symmetry is restored. The competition between ambient noise and the chiral bias due to physical fields and polarized radiation can be explored with this potential.

Resonance-enhanced laser-induced plasma spectroscopy: ambient gas effects

International Nuclear Information System (INIS)

Lui, S.L.; Cheung, N.H.

2003-01-01

When performing laser-induced plasma spectroscopy for elemental analysis, the sensitivity could be significantly enhanced if the plume was resonantly rekindled by a dye laser pulse. The extent of the enhancement was found to depend on the ambient gas. Air, nitrogen, helium, argon and xenon at pressures ranging from vacuum to 1 bar were investigated. In vacuum, the analyte signal was boosted because of reduced cooling, but it soon decayed as the plume freely expanded. By choosing the right ambient gas at the right pressure, the expanding plume could be confined as well as thermally insulated to maximize the analyte signal. For instance, an ambient of 13 mbar xenon yielded a signal-to-noise ratio of 110. That ratio was 53 when the pellet was ablated in air, and decreased further to 5 if the dye laser was tuned off resonance

Underwater Noise from a Wave Energy Converter Is Unlikely to Affect Marine Mammals.

Directory of Open Access Journals (Sweden)

Jakob Tougaard

Full Text Available Underwater noise was recorded from the Wavestar wave energy converter; a full-scale hydraulic point absorber, placed on a jack-up rig on the Danish North Sea coast. Noise was recorded 25 m from the converter with an autonomous recording unit (10 Hz to 20 kHz bandwidth. Median sound pressure levels (Leq in third-octave bands during operation of the converter were 106-109 dB re. 1 μPa in the range 125-250 Hz, 1-2 dB above ambient noise levels (statistically significant. Outside the range 125-250 Hz the noise from the converter was undetectable above the ambient noise. During start and stop of the converter a more powerful tone at 150 Hz (sound pressure level (Leq 121-125 dB re 1 μPa was easily detectable. This tone likely originated from the hydraulic pump which was used to lower the absorbers into the water and lift them out of the water at shutdown. Noise levels from the operating wave converter were so low that they would barely be audible to marine mammals and the likelihood of negative impact from the noise appears minimal. A likely explanation for the low noise emissions is the construction of the converter where all moving parts, except for the absorbers themselves, are placed above water on a jack-up rig. The results may thus not be directly transferable to other wave converter designs but do demonstrate that it is possible to harness wave energy without noise pollution to the marine environment.

Underwater Noise from a Wave Energy Converter Is Unlikely to Affect Marine Mammals.

Science.gov (United States)

Tougaard, Jakob

2015-01-01

Underwater noise was recorded from the Wavestar wave energy converter; a full-scale hydraulic point absorber, placed on a jack-up rig on the Danish North Sea coast. Noise was recorded 25 m from the converter with an autonomous recording unit (10 Hz to 20 kHz bandwidth). Median sound pressure levels (Leq) in third-octave bands during operation of the converter were 106-109 dB re. 1 μPa in the range 125-250 Hz, 1-2 dB above ambient noise levels (statistically significant). Outside the range 125-250 Hz the noise from the converter was undetectable above the ambient noise. During start and stop of the converter a more powerful tone at 150 Hz (sound pressure level (Leq) 121-125 dB re 1 μPa) was easily detectable. This tone likely originated from the hydraulic pump which was used to lower the absorbers into the water and lift them out of the water at shutdown. Noise levels from the operating wave converter were so low that they would barely be audible to marine mammals and the likelihood of negative impact from the noise appears minimal. A likely explanation for the low noise emissions is the construction of the converter where all moving parts, except for the absorbers themselves, are placed above water on a jack-up rig. The results may thus not be directly transferable to other wave converter designs but do demonstrate that it is possible to harness wave energy without noise pollution to the marine environment.

Detection capability of the IMS seismic network based on ambient seismic noise measurements

Science.gov (United States)

Gaebler, Peter J.; Ceranna, Lars

2016-04-01

All nuclear explosions - on the Earth's surface, underground, underwater or in the atmosphere - are banned by the Comprehensive Nuclear-Test-Ban Treaty (CTBT). As part of this treaty, a verification regime was put into place to detect, locate and characterize nuclear explosion testings at any time, by anyone and everywhere on the Earth. The International Monitoring System (IMS) plays a key role in the verification regime of the CTBT. Out of the different monitoring techniques used in the IMS, the seismic waveform approach is the most effective technology for monitoring nuclear underground testing and to identify and characterize potential nuclear events. This study introduces a method of seismic threshold monitoring to assess an upper magnitude limit of a potential seismic event in a certain given geographical region. The method is based on ambient seismic background noise measurements at the individual IMS seismic stations as well as on global distance correction terms for body wave magnitudes, which are calculated using the seismic reflectivity method. From our investigations we conclude that a global detection threshold of around mb 4.0 can be achieved using only stations from the primary seismic network, a clear latitudinal dependence for the detection threshold can be observed between northern and southern hemisphere. Including the seismic stations being part of the auxiliary seismic IMS network results in a slight improvement of global detection capability. However, including wave arrivals from distances greater than 120 degrees, mainly PKP-wave arrivals, leads to a significant improvement in average global detection capability. In special this leads to an improvement of the detection threshold on the southern hemisphere. We further investigate the dependence of the detection capability on spatial (latitude and longitude) and temporal (time) parameters, as well as on parameters such as source type and percentage of operational IMS stations.

Combined effects of road traffic noise and ambient air pollution in relation to risk for stroke?

DEFF Research Database (Denmark)

Sørensen, Mette; Lühdorf, Pernille; Ketzel, Matthias

2014-01-01

Exposure to road traffic noise and air pollution have both been associated with risk for stroke. The few studies including both exposures show inconsistent results. We aimed to investigate potential mutual confounding and combined effects between road traffic noise and air pollution in association...... to 2009 were identified in national registers and road traffic noise and air pollution were modeled for all addresses. Analyses were done using Cox regression. A higher mean annual exposure at time of diagnosis of 10µg/m(3) nitrogen dioxide (NO2) and 10dB road traffic noise at the residential address...... was found for combination of high noise and high NO2 (IRR=1.28; 95% CI=1.09-1.52). Fatal stroke was positively associated with air pollution and not with traffic noise. In conclusion, in mutually adjusted models road traffic noise and not air pollution was associated ischemic stroke, while only air...

A modified random decrement technique for modal identification from nonstationary ambient response data only

International Nuclear Information System (INIS)

Lin, Chang Sheng; Chiang, Dar Yun

2012-01-01

Modal identification is considered from response data of structural system under nonstationary ambient vibration. In a previous paper, we showed that by assuming the ambient excitation to be nonstationary white noise in the form of a product model, the nonstationary response signals can be converted into free-vibration data via the correlation technique. In the present paper, if the ambient excitation can be modeled as a nonstationary white noise in the form of a product model, then the nonstationary cross random decrement signatures of structural response evaluated at any fixed time instant are shown theoretically to be proportional to the nonstationary cross-correlation functions. The practical problem of insufficient data samples available for evaluating nonstationary random decrement signatures can be approximately resolved by first extracting the amplitude-modulating function from the response and then transforming the nonstationary responses into stationary ones. Modal-parameter identification can then be performed using the Ibrahim time-domain technique, which is effective at identifying closely spaced modes. The theory proposed can be further extended by using the filtering concept to cover the case of nonstationary color excitations. Numerical simulations confirm the validity of the proposed method for identification of modal parameters from nonstationary ambient response data

Monocrystalline fibres for low thermal noise suspension in advanced gravitational wave detectors

International Nuclear Information System (INIS)

Amico, P; Bosi, L; Gammaitoni, L; Losurdo, G; Marchesoni, F; Mazzoni, M; Parisi, D; Punturo, M; Stanga, R; Toncelli, A; Tonelli, M; Travasso, F; Vetrano, F; Vocca, H

2004-01-01

Thermal noise in mirror suspension will be the most severe fundamental limit to the low-frequency sensitivity of future interferometric gravitational wave detectors. We propose a new type of materials to realize low thermal noise suspension in such detectors. Monocrystalline suspension fibres are good candidates both for cryogenic and for ambient temperature interferometers. Material characteristics and a production facility are described in this paper

Monocrystalline fibres for low thermal noise suspension in advanced gravitational wave detectors

Energy Technology Data Exchange (ETDEWEB)

Amico, P [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Bosi, L [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Gammaitoni, L [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Losurdo, G [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze/Urbino, Florence (Italy); Marchesoni, F [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Mazzoni, M [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze/Urbino, Florence (Italy); Parisi, D [NEST-Dipartimento di Fisica, Universita di Pisa, Pisa (Italy); Punturo, M [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Stanga, R [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze/Urbino, Florence (Italy); Toncelli, A [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Pisa (Italy); Tonelli, M [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Pisa (Italy); Travasso, F [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Vetrano, F [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze/Urbino, Florence (Italy); Vocca, H [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy)

2004-03-07

Thermal noise in mirror suspension will be the most severe fundamental limit to the low-frequency sensitivity of future interferometric gravitational wave detectors. We propose a new type of materials to realize low thermal noise suspension in such detectors. Monocrystalline suspension fibres are good candidates both for cryogenic and for ambient temperature interferometers. Material characteristics and a production facility are described in this paper.

Ambient seismic noise interferometry in Hawai'i reveals long-range observability of volcanic tremor

Science.gov (United States)

Ballmer, Silke; Wolfe, Cecily; Okubo, Paul G.; Haney, Matt; Thurber, Clifford H.

2013-01-01

The use of seismic noise interferometry to retrieve Green's functions and the analysis of volcanic tremor are both useful in studying volcano dynamics. Whereas seismic noise interferometry allows long-range extraction of interpretable signals from a relatively weak noise wavefield, the characterization of volcanic tremor often requires a dense seismic array close to the source. We here show that standard processing of seismic noise interferometry yields volcanic tremor signals observable over large distances exceeding 50 km. Our study comprises 2.5 yr of data from the U.S. Geological Survey Hawaiian Volcano Observatory short period seismic network. Examining more than 700 station pairs, we find anomalous and temporally coherent signals that obscure the Green's functions. The time windows and frequency bands of these anomalous signals correspond well with the characteristics of previously studied volcanic tremor sources at Pu'u 'Ō'ō and Halema'uma'u craters. We use the derived noise cross-correlation functions to perform a grid-search for source location, confirming that these signals are surface waves originating from the known tremor sources. A grid-search with only distant stations verifies that useful tremor signals can indeed be recovered far from the source. Our results suggest that the specific data processing in seismic noise interferometry—typically used for Green's function retrieval—can aid in the study of both the wavefield and source location of volcanic tremor over large distances. In view of using the derived Green's functions to image heterogeneity and study temporal velocity changes at volcanic regions, however, our results illustrate how care should be taken when contamination by tremor may be present.

Evaluation studies of noise and air pollution during festival seasons in India.

Science.gov (United States)

Battalwar, D G; Meshram, S U; Yenkie, M K N; Puri, P J

2012-07-01

The present research work is based on assessment of noise levels and ambient air quality at selected locations during festival seasons in Nagpur city. The noise levels were exceeding the permissible limits almost at every location during the festival period. The huge emissions of smoke arising out bursting of firecrackers have significantly resulted into air pollution; particularly in terms of Sulphur Dioxide (SO2) and Respirable Suspended Particulate Matter (Fine Dust). The immediate effect of increasing noise levels is impairing of hearing that may cause auditory fatigue and finally lead to deafness.

Noise suppression in surface microseismic data by τ-p transform

Science.gov (United States)

Forghani-Arani, Farnoush; Batzle, Mike; Behura, Jyoti; Willis, Mark; Haines, Seth; Davidson, Michael

2013-01-01

Surface passive seismic methods are receiving increased attention for monitoring changes in reservoirs during the production of unconventional oil and gas. However, in passive seismic data the strong cultural and ambient noise (mainly surface-waves) decreases the effectiveness of these techniques. Hence, suppression of surface-waves is a critical step in surface microseismic monitoring. We apply a noise suppression technique, based on the τ — p transform, to a surface passive seismic dataset recorded over a Barnett Shale reservoir undergoing a hydraulic fracturing process. This technique not only improves the signal-to-noise ratios of added synthetic microseismic events, but it also preserves the event waveforms.

Rayleigh waves from correlation of seismic noise in Great Island of Tierra del Fuego, Argentina: Constraints on upper crustal structure

Directory of Open Access Journals (Sweden)

Carolina Buffoni

2018-01-01

Full Text Available In this study, the ambient seismic noise cross-correlation technique is applied to estimate the upper structure of the crust beneath Great Island of Tierra del Fuego (TdF, Argentina, by the analysis of short-period Rayleigh wave group velocities. The island, situated in the southernmost South America, is a key area of investigation among the interaction between the South American and Scotia plates and is considered as a very seismically active one. Through cross-correlating the vertical components of ambient seismic noise registered at four broadband stations in TdF, we were able to extract Rayleigh waves which were used to estimate group velocities in the period band of 2.5–16 s using a time-frequency analysis. Although ambient noise sources are distributed inhomogeneously, robust empirical Green's functions could be recovered from the cross-correlation of 12 months of ambient noise. The observed group velocities were inverted considering a non-linear iterative damped least-squares inversion procedure and several 1-D shear wave velocity models of the upper crust were obtained. According to the inversion results, the S-wave velocity ranges between 1.75 and 3.7 km/s in the first 10 km of crust, depending on the pair of stations considered. These results are in agreement to the major known surface and sub-surface geological and tectonic features known in the area. This study represents the first ambient seismic noise analysis in TdF in order to constraint the upper crust beneath this region. It can also be considered as a successful feasibility study for future analyses with a denser station deployment for a more detailed imaging of structure.

Crustal and upper mantle shear velocities of Iberia, the Alboran Sea, and North Africa from ambient noise and ballistic finite-frequency Rayleigh wave tomography

Science.gov (United States)

Palomeras, I.; Villasenor, A.; Thurner, S.; Levander, A.; Gallart, J.; mimoun, H.

2013-12-01

The complex Mesozoic-Cenozoic Alpine deformation in the western Mediterranean extends from the Pyrenees in northern Spain to the Atlas Mountains in southern Morocco. The Iberian plate was accreted to the European plate in late Cretaceous, resulting in the formation of the Pyrenees. Cenozoic African-European convergence resulted in subduction of the Tethys oceanic plate beneath Europe. Rapid Oligocene slab rollback from eastern Iberia spread eastward and southward, with the trench breaking into three segments by the time it reached the African coast. One trench segment moved southwestward and westward creating the Alboran Sea, floored by highly extended continental crust, and building the encircling Betics Rif mountains comprising the Gibraltar arc, and the Atlas mountains, which formed as the inversion of a Jurassic rift. A number of recent experiments have instrumented this region with broad-band arrays (the US PICASSO array, Spanish IberArray and Siberia arrays, the University of Munster array), which, including the Spanish, Portuguese, and Moroccan permanent networks, provide a combined array of 350 stations having an average interstation spacing of ~60 km. Taking advantage of this dense deployment, we have calculated the Rayleigh waves phase velocities from ambient noise for short periods (4 s to 40 s) and teleseismic events for longer periods (20 s to 167 s). Approximately 50,000 stations pairs were used to measure the phase velocity from ambient noise and more than 160 teleseismic events to measure phase velocity for longer periods. The inversion of the phase velocity dispersion curves provides a 3D shear velocity for the crust and uppermost mantle. Our results show differences between the various tectonic regions that extend to upper mantle depths (~200 km). In Iberia we obtain, on average, higher upper mantle shear velocities in the western Variscan region than in the younger eastern part. We map high upper mantle velocities (>4.6 km/s) beneath the

Binaural noise reduction via cue-preserving MMSE filter and adaptive-blocking-based noise PSD estimation

Science.gov (United States)

Azarpour, Masoumeh; Enzner, Gerald

2017-12-01

Binaural noise reduction, with applications for instance in hearing aids, has been a very significant challenge. This task relates to the optimal utilization of the available microphone signals for the estimation of the ambient noise characteristics and for the optimal filtering algorithm to separate the desired speech from the noise. The additional requirements of low computational complexity and low latency further complicate the design. A particular challenge results from the desired reconstruction of binaural speech input with spatial cue preservation. The latter essentially diminishes the utility of multiple-input/single-output filter-and-sum techniques such as beamforming. In this paper, we propose a comprehensive and effective signal processing configuration with which most of the aforementioned criteria can be met suitably. This relates especially to the requirement of efficient online adaptive processing for noise estimation and optimal filtering while preserving the binaural cues. Regarding noise estimation, we consider three different architectures: interaural (ITF), cross-relation (CR), and principal-component (PCA) target blocking. An objective comparison with two other noise PSD estimation algorithms demonstrates the superiority of the blocking-based noise estimators, especially the CR-based and ITF-based blocking architectures. Moreover, we present a new noise reduction filter based on minimum mean-square error (MMSE), which belongs to the class of common gain filters, hence being rigorous in terms of spatial cue preservation but also efficient and competitive for the acoustic noise reduction task. A formal real-time subjective listening test procedure is also developed in this paper. The proposed listening test enables a real-time assessment of the proposed computationally efficient noise reduction algorithms in a realistic acoustic environment, e.g., considering time-varying room impulse responses and the Lombard effect. The listening test outcome

Ambient Space and Ambient Sensation

DEFF Research Database (Denmark)

Schmidt, Ulrik

The ambient is the aesthetic production of the sensation of being surrounded. As a concept, 'ambient' is mostly used in relation to the music genre 'ambient music' and Brian Eno's idea of environmental background music. However, the production of ambient sensations must be regarded as a central...... aspect of the aesthetization of modern culture in general, from architecture, transport and urbanized lifeforms to film, sound art, installation art and digital environments. This presentation will discuss the key aspects of ambient aesthetization, including issues such as objectlessness...

Crustal surface wave velocity structure of the east Albany-Fraser Orogen, Western Australia, from ambient noise recordings

Science.gov (United States)

Sippl, C.; Kennett, B. L. N.; Tkalčić, H.; Gessner, K.; Spaggiari, C. V.

2017-09-01

Group and phase velocity maps in the period range 2-20 s for the Proterozoic east Albany-Fraser Orogen, Western Australia, are extracted from ambient seismic noise recorded with the 70-station ALFREX array. This 2 yr temporary installation provided detailed coverage across the orogen and the edge of the Neoarchean Yilgarn Craton, a region where no passive seismic studies of this scale have occurred to date. The surface wave velocities are rather high overall (>3 km s-1 nearly everywhere), as expected for exposed Proterozoic basement rocks. No clear signature of the transition between Yilgarn Craton and Albany-Fraser Orogen is observed, but several strong anomalies corresponding to more local geological features were obtained. A prominent, NE-elongated high-velocity anomaly in the northern part of the array is coincident with a Bouguer gravity high caused by the upper crustal metamorphic rocks of the Fraser Zone. This feature disappears towards longer periods, which hints at an exclusively upper crustal origin for this anomaly. Further east, the limestones of the Cenozoic Eucla Basin are clearly imaged as a pronounced low-velocity zone at short periods, but the prevalence of low velocities to periods of ≥5 s implies that the uppermost basement in this area is likewise slow. At longer periods, slightly above-average surface wave velocities are imaged below the Eucla Basin.

Humans, Fish, and Whales: How Right Whales Modify Calling Behavior in Response to Shifting Background Noise Conditions.

Science.gov (United States)

Parks, Susan E; Groch, Karina; Flores, Paulo; Sousa-Lima, Renata; Urazghildiiev, Ildar R

2016-01-01

This study investigates the role of behavioral plasticity in the variation of sound production of southern right whales (Eubalaena australis) in response to changes in the ambient background noise conditions. Data were collected from southern right whales in Brazilian waters in October and November 2011. The goal of this study was to quantify differences in right whale vocalizations recorded in low background noise as a control, fish chorus noise, and vessel noise. Variation in call parameters were detected among the three background noise conditions and have implications for future studies of noise effects on whale sound production.

[The effects of noise on sleep and their possible repercussions on health].

Science.gov (United States)

Muzet, Alain

2006-11-01

Sleep is a physiological recuperative state susceptible to be disturbed or reduced in length under external stimuli, such as noise, one of the most frequent ambient factors. Sleep disturbance is often accompanied by a reduced quality of the following waking period. The health effects of prolonged exposure to noise concern life quality, as expressed subjectively by the sleeper, as well as probable effect on cardiovascular function through a non specific aggression related to stress.

Combined effects of road traffic noise and ambient air pollution in relation to risk for stroke?

Science.gov (United States)

Sørensen, Mette; Lühdorf, Pernille; Ketzel, Matthias; Andersen, Zorana J; Tjønneland, Anne; Overvad, Kim; Raaschou-Nielsen, Ole

2014-08-01

Exposure to road traffic noise and air pollution have both been associated with risk for stroke. The few studies including both exposures show inconsistent results. We aimed to investigate potential mutual confounding and combined effects between road traffic noise and air pollution in association with risk for stroke. In a population-based cohort of 57,053 people aged 50-64 years at enrollment, we identified 1999 incident stroke cases in national registries, followed by validation through medical records. Mean follow-up time was 11.2 years. Present and historical residential addresses from 1987 to 2009 were identified in national registers and road traffic noise and air pollution were modeled for all addresses. Analyses were done using Cox regression. A higher mean annual exposure at time of diagnosis of 10 µg/m(3) nitrogen dioxide (NO2) and 10 dB road traffic noise at the residential address was associated with ischemic stroke with incidence rate ratios (IRR) of 1.11 (95% CI: 1.03, 1.20) and 1.16 (95% CI: 1.07, 1.24), respectively, in single exposure models. In two-exposure models road traffic noise (IRR: 1.15) and not NO2 (IRR: 1.02) was associated with ischemic stroke. The strongest association was found for combination of high noise and high NO2 (IRR=1.28; 95% CI=1.09-1.52). Fatal stroke was positively associated with air pollution and not with traffic noise. In conclusion, in mutually adjusted models road traffic noise and not air pollution was associated ischemic stroke, while only air pollution affected risk for fatal strokes. There were indications of combined effects. Copyright © 2014 Elsevier Inc. All rights reserved.

Microscopic Sources of Paramagnetic Noise on α-Al2O3 Substrates for Superconducting Qubits

Science.gov (United States)

Dubois, Jonathan; Lee, Donghwa; Lordi, Vince

2014-03-01

Superconducting qubits (SQs) represent a promising route to achieving a scalable quantum computer. However, the coupling between electro-dynamic qubits and (as yet largely unidentified) ambient parasitic noise sources has so far limited the functionality of current SQs by limiting coherence times of the quantum states below a practical threshold for measurement and manipulation. Further improvement can be enabled by a detailed understanding of the various noise sources afflicting SQs. In this work, first principles density functional theory (DFT) calculations are employed to identify the microscopic origins of magnetic noise sources in SQs on an α-Al2O3 substrate. The results indicate that it is unlikely that the existence of intrinsic point defects and defect complexes in the substrate are responsible for low frequency noise in these systems. Rather, a comprehensive analysis of extrinsic defects shows that surface aluminum ions interacting with ambient molecules will form a bath of magnetic moments that can couple to the SQ paramagnetically. The microscopic origin of this magnetic noise source is discussed and strategies for ameliorating the effects of these magnetic defects are proposed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

VS of the uppermost crust structure of the Campi Flegrei caldera (southern Italy) from ambient noise Rayleigh wave analysis

Science.gov (United States)

Costanzo, M. R.; Nunziata, C.; Strollo, R.

2017-11-01

Shear wave velocities (VS) are defined in the uppermost 1-2 km of the Campi Flegrei caldera through the non-linear inversion of the group velocity dispersion curves of fundamental-mode Rayleigh waves extracted from ambient noise cross-correlations between two receivers. Noise recordings, three months long, at 12 seismic stations are cross-correlated between all couples of stations. The experiment provided successful results along 54 paths (inter-stations distance), of which 27 sampled a depth > 1 km. VS contour lines are drawn from 0.06 km b.s.l. to 1 km depth b.s.l. and show difference between the offshore (gulf of Pozzuoli and coastline) and the onshore areas. At 0.06 km b.s.l., the gulf of Pozzuoli and the coastline are characterized by VS of 0.3-0.5 km/s and of 0.5-0.7 km/s, respectively. Such velocities are typical of Neapolitan pyroclastic soils and fractured or altered tuffs. The inland shows VS in the range 0.7-0.9 km/s, typical of Neapolitan compact tuffs. Velocities increase with depth and, at 1 km depth b.s.l., velocities lower than 1.5 km/s are still present in the gulf and along the coastline while velocities higher than 1.9 km/s characterize the eastern sector (grossly coincident with the Neapolitan Yellow Tuff caldera rim), the S. Vito plain and the area between Solfatara and SW of Astroni. Such features are much more evident along two cross-sections drawn in the offshore and onshore sectors by integrating our VS models with literature data. Our models join previous noise cross-correlation studies at greater scale at depths of 0.7-0.8 km, hence the picture of the Campi Flegrei caldera is shown up to a depth of 15 km. VS of about 1.7 km/s, corresponding to compression velocities (VP) of about 3 km/s (computed by using the VP/VS ratio resulted in the inversion), are found at depths of 1.1 km, in the centre of the gulf of Pozzuoli, and at a depth of about 0.7 km b.s.l. onshore. An increment of VS velocity ( 1.9-2.0 km/s) is locally observed onshore

Effect of noise on comfort in open-plan offices: application of an assessment questionnaire.

Science.gov (United States)

Perrin Jegen, N; Chevret, P

2017-01-01

Open-plan offices account for 60% of French office workspaces. The noise levels recorded in this type of environment are much lower than those encountered in industrial workplaces. Nevertheless, surveys show that noise is considered by employees as the main source of discomfort. A first questionnaire dedicated to noise discomfort was produced in 2013 and tested on a panel made up of 217 people working in 7 French companies. Today, it also makes it possible to address the issues of fatigue related to ambient sound, but above all, the survey aims to study the differences in how ambient noise is perceived depending on the type of open-plan office. On the basis of that new version, a second survey has been conducted in 23 open-plan offices, making it possible to collect the responses from 617 employees. Most of the results of the first survey have been confirmed, with an increase in the significance of the statistical analyses. Moreover, French Standard NF S 31-199, which is currently being drafted, establishes a typology of open-plan office spaces according to the types of work done in them. Based on this typology, it appears that when dealing with the impact on noise on workers, a distinction has to be made between the types of open plan offices. Practitioner Summary: Surveys conducted in open-plan offices show that noise is considered by employees as the main source of discomfort even if the noise recorded in this type of environment is not hazardous. This work presents the result of a large survey dedicated to noise discomfort conducted in 23 open-plan offices.

Impact of noise and air pollution on pregnancy outcomes.

Science.gov (United States)

Gehring, Ulrike; Tamburic, Lillian; Sbihi, Hind; Davies, Hugh W; Brauer, Michael

2014-05-01

Motorized traffic is an important source of both air pollution and community noise. While there is growing evidence for an adverse effect of ambient air pollution on reproductive health, little is known about the association between traffic noise and pregnancy outcomes. We evaluated the impact of residential noise exposure on small size for gestational age, preterm birth, term birth weight, and low birth weight at term in a population-based cohort study, for which we previously reported associations between air pollution and pregnancy outcomes. We also evaluated potential confounding of air pollution effects by noise and vice versa. Linked administrative health data sets were used to identify 68,238 singleton births (1999-2002) in Vancouver, British Columbia, Canada, with complete covariate data (sex, ethnicity, parity, birth month and year, income, and education) and maternal residential history. We estimated exposure to noise with a deterministic model (CadnaA) and exposure to air pollution using temporally adjusted land-use regression models and inverse distance weighting of stationary monitors for the entire pregnancy. Noise exposure was negatively associated with term birth weight (mean difference = -19 [95% confidence interval = -23 to -15] g per 6 dB(A)). In joint air pollution-noise models, associations between noise and term birth weight remained largely unchanged, whereas associations decreased for all air pollutants. Traffic may affect birth weight through exposure to both air pollution and noise.

A influência do ruído ambiental no desempenho de escolares nos testes de padrão tonal de frequência e padrão tonal de duração Environmental noise influence on student performance in the Frequency Pattern Tests and Duration Pattern Tests

Directory of Open Access Journals (Sweden)

Ludimila Souza Nascimento

2012-06-01

Full Text Available OBJETIVO: caracterizar o desempenho de escolares nos testes de padrão tonal de frequência e padrão tonal de duração no silêncio e na presença de ruído ambiental. METODO: trata-se de estudo experimental transversal, com amostra de conveniência, composta por 70 estudantes, que responderam a um formulário de percepção do ruído ambiental. O nível de ruído da escola foi avaliado com medidor de nível de pressão sonora. Os estudantes foram submetidos à avaliações (fala, motricidade orofacial, linguagem e simplificada do processamento auditivo e distribuídos em dois grupos (G1 sem alteração fonoaudiológica e G2 com alteração fonoaudiológica. Foram realizados também os testes de padrão tonal de frequência e duração (silêncio e ruído. RESULTADOS: o nível médio de pressão sonora da escola variou de 57,2 dB(A na sala de informática a 83,6 dB(A na quadra de esportes. Segundo os estudantes, o que mais interfere em suas atividades é o barulho de conversas durante a aula. Quanto aos testes de padrão tonal de frequência (TPF e duração (TPD, observou-se que a média de acertos no ambiente silencioso foi maior que no ambiente ruidoso. O G1 apresentou melhor desempenho no TPD e TPF que G2. No ruído houve piora no desempenho dos dois grupos (G1 e G2 nos testes. CONCLUSÃO: os níveis de pressão sonora da escola encontram-se elevados e fora do padrão recomendado pelas normas nacionais. No ruído, houve piora no desempenho dos testes nos dois grupos estudados.PURPOSE: to characterize student performance in Frequency Pattern Test (FPT and Duration Pattern Test (DPT in a silent ambient and under noise. METHOD: experimental cross-sectional study, measured in a convenience sample. Survey made up by 70 students who answered a form on their noise perception. School's noise level was evaluated using physical measurements. Students were submitted to previous evaluations (speech, language, and auditory processing and then splinted

3-D Upper-Mantle Shear Velocity Model Beneath the Contiguous United States Based on Broadband Surface Wave from Ambient Seismic Noise

Science.gov (United States)

Xie, Jun; Chu, Risheng; Yang, Yingjie

2018-05-01

Ambient noise seismic tomography has been widely used to study crustal and upper-mantle shear velocity structures. Most studies, however, concentrate on short period (structure on a continental scale. We use broadband Rayleigh wave phase velocities to obtain a 3-D V S structures beneath the contiguous United States at period band of 10-150 s. During the inversion, 1-D shear wave velocity profile is parameterized using B-spline at each grid point and is inverted with nonlinear Markov Chain Monte Carlo method. Then, a 3-D shear velocity model is constructed by assembling all the 1-D shear velocity profiles. Our model is overall consistent with existing models which are based on multiple datasets or data from earthquakes. Our model along with the other post-USArray models reveal lithosphere structures in the upper mantle, which are consistent with the geological tectonic background (e.g., the craton root and regional upwelling provinces). The model has comparable resolution on lithosphere structures compared with many published results and can be used for future detailed regional or continental studies and analysis.

Seismic exploration?scale velocities and structure from ambient seismic noise (>1?Hz)

NARCIS (Netherlands)

Draganov, D.S.; Campman, X.; Thorbecke, J.W.; Verdel, A.; Wapenaar, C.P.A.

2013-01-01

The successful surface waves retrieval in solid?Earth seismology using long?time correlations and subsequent tomographic images of the crust have sparked interest in extraction of subsurface information from noise in the exploration seismology. Subsurface information in exploration seismology is

Seismic exploration-scale velocities and structure from ambient seismic noise (>1 Hz)

NARCIS (Netherlands)

Draganov, D.; Campman, X.; Thorbecke, J.; Verdel, A.; Wapenaar, K.

2013-01-01

The successful surface waves retrieval in solid-Earth seismology using long-time correlations and subsequent tomographic images of the crust have sparked interest in extraction of subsurface information from noise in the exploration seismology. Subsurface information in exploration seismology is

Empirical Green's tensor retrieved from ambient noise cross-correlations at The Geysers geothermal field, Northern California

Science.gov (United States)

Nayak, Avinash; Taira, Taka'aki; Dreger, Douglas S.; Gritto, Roland

2018-04-01

We retrieve empirical Green's functions in the frequency range (˜0.2-0.9 Hz) for interstation distances ranging from ˜1 to ˜30 km (˜0.22 to ˜6.5 times the wavelength) at The Geysers geothermal field, Northern California, from coherency of ambient seismic noise being recorded by a variety of sensors (broad-band, short-period surface and borehole sensors, and one accelerometer). The applied methodology preserves the intercomponent relative amplitudes of the nine-component Green's tensor that allows us to directly compare noise-derived Green's functions (NGFs) with normalized displacement waveforms of complete single-force synthetic Green's functions (SGFs) computed with various 1-D and 3-D velocity models using the frequency-wavenumber integration method and a 3-D finite-difference wave propagation method, respectively. These comparisons provide an effective means of evaluating the suitability of different velocity models to different regions of The Geysers, and assessing the quality of the sensors and the NGFs. In the T-Tangential, R-Radial, Z-Vertical reference frame, the TT, RR, RZ, ZR and ZZ components (first component: force direction, second component: response direction) of NGFs show clear surface waves and even body-wave phases for many station pairs. They are also broadly consistent in phase and intercomponent relative amplitudes with SGFs for the known local seismic velocity structure that was derived primarily from body-wave traveltime tomography, even at interstation distances less than one wavelength. We also find anomalous large amplitudes in TR, TZ, RT and ZT components of NGFs at small interstation distances (≲4 km) that can be attributed to ˜10°-30° sensor misalignments at many stations inferred from analysis of longer period teleseismic waveforms. After correcting for sensor misalignments, significant residual amplitudes in these components for some longer interstation distance (≳8 km) paths are better reproduced by the 3-D velocity

Towards equitable solutions to siting and noise problems in windfarms

International Nuclear Information System (INIS)

Larke, C.; Woodbridge, A.; Hayes, M.

1991-01-01

For windfarming to be a successful long-term business, it is essential that wind developments are good neighbours, and good neighbours do not keep you awake at night. Very low rural ambients of 20-32 dB(A) at turbine cut-in windspeeds and for half the time at operating windspeeds ambients below about 40 dB(A) show a large potential problem. The settlement patterns necessitate a target of 400m distance with no noise nuisance to maintain accessibility to over 2 GW of windsites in Western Britain. At least one manufacturer has produced a turbine meeting this requirement. (author)

The importance of ambient sound level to characterise anuran habitat.

Directory of Open Access Journals (Sweden)

Sandra Goutte

Full Text Available Habitat characterisation is a pivotal step of any animal ecology study. The choice of variables used to describe habitats is crucial and need to be relevant to the ecology and behaviour of the species, in order to reflect biologically meaningful distribution patterns. In many species, acoustic communication is critical to individuals' interactions, and it is expected that ambient acoustic conditions impact their local distribution. Yet, classic animal ecology rarely integrates an acoustic dimension in habitat descriptions. Here we show that ambient sound pressure level (SPL is a strong predictor of calling site selection in acoustically active frog species. In comparison to six other habitat-related variables (i.e. air and water temperature, depth, width and slope of the stream, substrate, SPL had the most important explanatory power in microhabitat selection for the 34 sampled species. Ambient noise was particularly useful in differentiating two stream-associated guilds: torrents and calmer streams dwelling species. Guild definitions were strongly supported by SPL, whereas slope, which is commonly used in stream-associated habitat, had a weak explanatory power. Moreover, slope measures are non-standardized across studies and are difficult to assess at small scale. We argue that including an acoustic descriptor will improve habitat-species analyses for many acoustically active taxa. SPL integrates habitat topology and temporal information (such as weather and hour of the day, for example and is a simple and precise measure. We suggest that habitat description in animal ecology should include an acoustic measure such as noise level because it may explain previously misunderstood distribution patterns.

Rayleigh wave group velocity and shear wave velocity structure in the San Francisco Bay region from ambient noise tomography

Science.gov (United States)

Li, Peng; Thurber, Clifford

2018-06-01

We derive new Rayleigh wave group velocity models and a 3-D shear wave velocity model of the upper crust in the San Francisco Bay region using an adaptive grid ambient noise tomography algorithm and 6 months of continuous seismic data from 174 seismic stations from multiple networks. The resolution of the group velocity models is 0.1°-0.2° for short periods (˜3 s) and 0.3°-0.4° for long periods (˜10 s). The new shear wave velocity model of the upper crust reveals a number of important structures. We find distinct velocity contrasts at the Golden Gate segment of the San Andreas Fault, the West Napa Fault, central part of the Hayward Fault and southern part of the Calaveras Fault. Low shear wave velocities are mainly located in Tertiary and Quaternary basins, for instance, La Honda Basin, Livermore Valley and the western and eastern edges of Santa Clara Valley. Low shear wave velocities are also observed at the Sonoma volcanic field. Areas of high shear wave velocity include the Santa Lucia Range, the Gabilan Range and Ben Lomond Plutons, and the Diablo Range, where Franciscan Complex or Silinian rocks are exposed.

On measuring surface wave phase velocity from station–station cross-correlation of ambient signal

DEFF Research Database (Denmark)

Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie

2012-01-01

We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one met...

Anthropogenic noise compromises the anti-predator behaviour of the European seabass, Dicentrarchus labrax (L.).

Science.gov (United States)

Spiga, Ilaria; Aldred, Nicholas; Caldwell, Gary S

2017-09-15

Anthropogenic noise is a significant pollutant of the world's oceans, affecting behavioural and physiological traits in a range of species, including anti-predator behaviours. Using the open field test, we investigated the effects of recordings of piling and drilling noise on the anti-predator behaviour of captive juvenile European seabass in response to a visual stimulus (a predatory mimic). The impulsive nature of piling noise triggered a reflexive startle response, which contrasted the behaviour elicited by the continuous drilling noise. When presented with the predatory mimic, fish exposed to both piling and drilling noise explored the experimental arena more extensively than control fish exposed to ambient noise. Fish under drilling and piling conditions also exhibited reduced predator inspection behaviour. Piling and drilling noise induced stress as measured by ventilation rate. This study provides further evidence that the behaviour and physiology of European seabass is significantly affected by exposure to elevated noise levels. Copyright © 2017. Published by Elsevier Ltd.

Listening to the Deep: Live monitoring of ocean noise and cetacean acoustic signals

OpenAIRE

André, Michel; Van der Schaar, Mike Connor Roger Malcolm; Zaugg, Serge Alain; Houégnigan, Ludwig; Sánchez, A.M.; Castell, Joan

2011-01-01

The development and broad use of passive acoustic monitoring techniques have the potential to help assessing the large-scale influence of artificial noise on marine organisms and ecosystems. Deep-sea observatories have the potential to play a key role in understanding these recent acoustic changes. LIDO(Listening to the Deep Ocean Environment) is an international project that is allowing the real-time longterm monitoring of marine ambient noise as well as marine mammal sounds at cabled and...

Effects of industrial noise on wildlife : issues and challenges in Alberta

Energy Technology Data Exchange (ETDEWEB)

Burke, D.; Lapka, S. [Alberta Energy and Utilities Board, Calgary, AB (Canada)

2007-07-01

The effects of noise from industrial activities on wildlife was examined with particular reference to the potential impacts of noise on caribou and grizzly bears from the Mackenzie Gas pipeline project. In Alberta, environmental noise requirements for oil and gas production facilities are outlined in the Alberta Energy and Utilities Board (EUB) Noise Control Directive 038. The requirements provide protection for human receptors, but not for wildlife. In order to ensure accurate assessments of the effects that industrial noise is having on wildlife, appropriate study methods must be developed to identify, quantify, and assess wildlife responses to noise. Without this knowledge, noise level thresholds for wildlife species cannot be established. A literature review was presented to demonstrate the range of published information on noise effects on wildlife and to highlight information that is relevant for the development of noise criteria for wildlife. It was concluded that wildlife noise thresholds are unknown, evidence for habituation to industrial facilities is limited, and long-term effects are generally unknown. Preliminary studies do not show any clear indication that observed reactions of wild animals are in response to noise. As such, development of regulatory criteria for wildlife noise control is not recommended at this time. The EUB will continue to keep up to date in wildlife related noise issues and will maintain the existing philosophy to limit noise to 5dB above ambient and to control dBA levels at 1500 m from facility fence lines. 57 refs., 1 fig.

Noise Annoyance in Urban Children: A Cross-Sectional Population-Based Study

Science.gov (United States)

Grelat, Natacha; Houot, Hélène; Pujol, Sophie; Levain, Jean-Pierre; Defrance, Jérôme; Mariet, Anne-Sophie; Mauny, Frédéric

2016-01-01

Acoustical and non-acoustical factors influencing noise annoyance in adults have been well-documented in recent years; however, similar knowledge is lacking in children. The aim of this study was to quantify the annoyance caused by chronic ambient noise at home in children and to assess the relationship between these children′s noise annoyance level and individual and contextual factors in the surrounding urban area. A cross sectional population-based study was conducted including 517 children attending primary school in a European city. Noise annoyance was measured using a self-report questionnaire adapted for children. Six noise exposure level indicators were built at different locations at increasing distances from the child′s bedroom window using a validated strategic noise map. Multilevel logistic models were constructed to investigate factors associated with noise annoyance in children. Noise indicators in front of the child′s bedroom (p ≤ 0.01), family residential satisfaction (p ≤ 0.03) and socioeconomic characteristics of the individuals and their neighbourhood (p ≤ 0.05) remained associated with child annoyance. These findings illustrate the complex relationships between our environment, how we may perceive it, social factors and health. Better understanding of these relationships will undoubtedly allow us to more effectively quantify the actual effect of noise on human health. PMID:27801858

Double-step annealing and ambient effects on phosphorus implanted emitters in silicon

International Nuclear Information System (INIS)

Koji, T.; Tseng, W.F.; Mayer, J.W.; Suganuma, T.

1979-01-01

Emitters of npn silicon bipolar transistors have been made by a phosphorus implantation at 50 keV P + to a dose of 1 x 10 16 cm -2 . This was followed by high temperature processes to reduce lattice disorder, to drive-in the phosphorus atoms, and to form oxide layers. The first process step was carried out by using single- and double-step anneals in various ambients (dry N 2 , dry 0 2 and steam) while the drive-in and oxidation steps were common for all structures. Electrical measurements on emitter/base leakage current, low frequency (popcorn) noise and current gain showed that the annealing ambient had a major influence. The transistors with implanted emitters annealed in a dry N 2 ambient are comparable to commercial ones with thermally-diffused emitters. Transmission electron microscopy observations on samples annealed in steam ambients revealed dislocations extending into the sidewall of the emitter/base junction. This sidewell penetration of dislocations is the main origin of the degradation of the emitter/base junction characteristics. (author)

Gestational diabetes mellitus and exposure to ambient air pollution and road traffic noise

DEFF Research Database (Denmark)

Pedersen, Marie; Olsen, Sjurdur F; Halldorsson, Thorhallur I

2017-01-01

pollution and road traffic noise on GDM in a prospective cohort. Methods: We identified GDM cases from self-reports and hospital records, using two different criteria, among 72,745 singleton pregnancies (1997–2002) from the Danish National Birth Cohort. We modeled nitrogen dioxide (NO2) and noise from road...... traffic (Lden) exposure at all pregnancy addresses. Results: According to the two diagnostic criteria: the Danish clinical guidelines, which was our main outcome, and the WHO standard during recruitment period, a total of 565 and 210 women, respectively, had GDM. For both exposures no risk was evident......: No risk was evident for the common Danish criterion of GDM. NO2 was associated with higher risk for GDM according to the WHO criterion, which might be due to selection bias....

A Near Real-Time Seismic Exploration and Monitoring (i.e., Ambient Seismic Noise Interferometry) Solution Based Upon a Novel "At the Edge" Approach that Leverages Commercially Available Digitizers, Embedded Systems, and an Open-Source Big Data Architecture

Science.gov (United States)

Sepulveda, F.; Thangraj, J. S.; Quiros, D.; Pulliam, J.; Queen, J. H.; Queen, M.; Iovenitti, J. L.

2017-12-01

Seismic interferometry that makes use of ambient noise requires that cross-correlations of data recorded at two or more stations be stacked over a "long enough" time interval that off-axis sources cancel and the estimated inter-station Green's function converges to the actual function. However, the optimal length of the recording period depends on the characteristics of ambient noise at the site, which vary over time and are therefore not known before data acquisition. Data acquisition parameters cannot be planned in ways that will ensure success while minimizing cost and effort. Experiment durations are typically either too long or too short. Automated, in-field processing can provide inter-station Green's functions in near-real-time, allowing for the immediate evaluation of results and enabling operators to alter data acquisition parameters before demobilizing. We report on the design, system integration, and testing of a strategy for the automation of data acquisition, distribution, and processing of ambient noise using industry-standard, widely-available instrumentation (Reftek 130-01 digitizers and 4.5 Hz geophones). Our solution utilizes an inexpensive embedded system (Raspberry Pi 3), which is configured to acquire data from the Reftek and insert it into a big data store called Apache Cassandra. Cassandra distributes and maintains up-to-date copies of the data, through a WiFi network, as defined by tunable consistency levels and replication factors thus allowing for efficient multi-station computations. At regular intervals, data is extracted from Cassandra and is used to compute Green's functions for all receiver pairs. Results are reviewed and progress toward convergence can be assessed. We successfully tested a 20-node prototype of what we call the "Raspberry Pi-Enhanced Reftek" (RaPiER) array at the Soda Lake Geothermal Field in Nevada in June 2017. While intermittent problems with the WiFi network interfered with the real-time data delivery from some

Assessment of noise environment during construction of a major bridge and associated approach road.

Science.gov (United States)

Roy, T K; Mukhopadhyay, A R; Ghosh, S K; Majumder, G

2011-10-01

In this paper a methodology to quantify the noise environment, during a major bridge construction and upgrading approach road connectivity, has been provided. Noise levels were monitored at eleven sites. These eleven sites have been classified into three categories - commercial, residential and silence zones. The study was carried out to measure the ambient noise levels in all the eleven sites falling in the above three categories during both day and night times considering both "working" and "non-working" days. It was found that the mean noise level during night time was more, compared to that during day time for commercial, residential as well as silence zones. The likely causes of more noise during night time have been explored. Appropriate remedial measures have been suggested to reduce the noise levels. In addition, the noise levels in the above three zones have been compared, wherever feasible statistically, with the respective zonal standards. Significance has been found in all the cases. The underlying causes and remedies have been provided.

Anthropogenic noise playback impairs embryonic development and increases mortality in a marine invertebrate

Science.gov (United States)

Nedelec, Sophie L.; Radford, Andrew N.; Simpson, Stephen D.; Nedelec, Brendan; Lecchini, David; Mills, Suzanne C.

2014-07-01

Human activities can create noise pollution and there is increasing international concern about how this may impact wildlife. There is evidence that anthropogenic noise may have detrimental effects on behaviour and physiology in many species but there are few examples of experiments showing how fitness may be directly affected. Here we use a split-brood, counterbalanced, field experiment to investigate the effect of repeated boat-noise playback during early life on the development and survival of a marine invertebrate, the sea hare Stylocheilus striatus at Moorea Island (French Polynesia). We found that exposure to boat-noise playback, compared to ambient-noise playback, reduced successful development of embryos by 21% and additionally increased mortality of recently hatched larvae by 22%. Our work, on an understudied but ecologically and socio-economically important taxon, demonstrates that anthropogenic noise can affect individual fitness. Fitness costs early in life have a fundamental influence on population dynamics and resilience, with potential implications for community structure and function.

Environmental noise levels affect the activity budget of the Florida manatee

Science.gov (United States)

Miksis-Olds, Jennifer L.; Donaghay, Percy L.; Miller, James H.; Tyack, Peter L.

2005-09-01

Manatees inhabit coastal bays, lagoons, and estuaries because they are dependent on the aquatic vegetation that grows in shallow waters. Food requirements force manatees to occupy the same areas in which human activities are the greatest. Noise produced from human activities has the potential to affect these animals by eliciting responses ranging from mild behavioral changes to extreme aversion. This study quantifies the behavioral responses of manatees to both changing levels of ambient noise and transient noise sources. Results indicate that elevated environmental noise levels do affect the overall activity budget of this species. The proportion of time manatees spend feeding, milling, and traveling in critical habitats changed as a function of noise level. More time was spent in the directed, goal-oriented behaviors of feeding and traveling, while less time was spent milling when noise levels were highest. The animals also responded to the transient noise of approaching vessels with changes in behavioral state and movements out of the geographical area. This suggests that manatees detect and respond to changes in environmental noise levels. Whether these changes legally constitute harassment and produce biologically significant effects need to be addressed with hypothesis-driven experiments and long-term monitoring. [For Animal Bioacoustics Best Student Paper Award.

Shear velocity model for the westernmost Mediterranean from ambient noise and ballistic finite-frequency Rayleigh wave tomography

Science.gov (United States)

Palomeras, I.; Villasenor, A.; Thurner, S.; Levander, A.; Gallart, J.; Harnafi, M.

2014-12-01

The westernmost Mediterranean comprises the Iberian Peninsula and Morocco, separated by the Alboran Sea and the Algerian Basin. From north to south this region consists of the Pyrenees, resulting from Iberia-Eurasia collision; the Iberian Massif, which has been undeformed since the end of the Paleozoic; the Central System and Iberian Chain, regions with intracontinental Oligocene-Miocene deformation; the Gibraltar Arc (Betics, Rif and Alboran terranes), resulting from post-Oligocene subduction roll-back; and the Atlas Mountains. We analyzed data from recent broad-band array deployments and permanent stations in the area (IberArray and Siberia arrays, the PICASSO array, the University of Munster array, and the Spanish, Portuguese and Moroccan National Networks) to characterize its lithospheric structure. The combined array of 350 stations has an average interstation spacing of ~60 km. We calculated the Rayleigh waves phase velocities from ambient noise (periods 4 to 40 s) and teleseismic events (periods 20 to 167 s). We inverted the phase velocities to obtain a shear velocity model for the lithosphere to ~200 km depth. Our results correlate well with the surface expression of the main structural units with higher crustal velocity for the Iberian Massif than for the Alpine Iberia and Atlas Mountains. The Gibraltar Arc has lower crustal shear velocities than the regional average at all crustal depths. It also shows an arc shaped anomaly with high upper mantle velocities (>4.6 km/s) at shallow depths (volcanic fields in Iberia and Morocco, indicative of high temperatures at relatively shallow depths, and suggesting that the lithosphere has been removed beneath these areas.

Calling at the highway: The spatiotemporal constraint of road noise on Pacific chorus frog communication.

Science.gov (United States)

Nelson, Danielle V; Klinck, Holger; Carbaugh-Rutland, Alexander; Mathis, Codey L; Morzillo, Anita T; Garcia, Tiffany S

2017-01-01

Loss of acoustic habitat due to anthropogenic noise is a key environmental stressor for vocal amphibian species, a taxonomic group that is experiencing global population declines. The Pacific chorus frog ( Pseudacris regilla ) is the most common vocal species of the Pacific Northwest and can occupy human-dominated habitat types, including agricultural and urban wetlands. This species is exposed to anthropogenic noise, which can interfere with vocalizations during the breeding season. We hypothesized that Pacific chorus frogs would alter the spatial and temporal structure of their breeding vocalizations in response to road noise, a widespread anthropogenic stressor. We compared Pacific chorus frog call structure and ambient road noise levels along a gradient of road noise exposures in the Willamette Valley, Oregon, USA. We used both passive acoustic monitoring and directional recordings to determine source level (i.e., amplitude or volume), dominant frequency (i.e., pitch), call duration, and call rate of individual frogs and to quantify ambient road noise levels. Pacific chorus frogs were unable to change their vocalizations to compensate for road noise. A model of the active space and time ("spatiotemporal communication") over which a Pacific chorus frog vocalization could be heard revealed that in high-noise habitats, spatiotemporal communication was drastically reduced for an individual. This may have implications for the reproductive success of this species, which relies on specific call repertoires to portray relative fitness and attract mates. Using the acoustic call parameters defined by this study (frequency, source level, call rate, and call duration), we developed a simplified model of acoustic communication space-time for this species. This model can be used in combination with models that determine the insertion loss for various acoustic barriers to define the impact of anthropogenic noise on the radius of communication in threatened species

A user-operated test of suprathreshold acuity in noise for adult hearing screening: The SUN (Speech Understanding in Noise) test.

Science.gov (United States)

Paglialonga, Alessia; Tognola, Gabriella; Grandori, Ferdinando

2014-09-01

A novel, user-operated test of suprathreshold acuity in noise for use in adult hearing screening (AHS) was developed. The Speech Understanding in Noise test (SUN) is a speech-in-noise test that makes use of a list of vowel-consonant-vowel (VCV) stimuli in background noise presented in a three-alternative forced choice (3AFC) paradigm by means of a touch sensitive screen. The test is automated, easy-to-use, and provides self-explanatory results (i.e., 'no hearing difficulties', or 'a hearing check would be advisable', or 'a hearing check is recommended'). The test was developed from its building blocks (VCVs and speech-shaped noise) through two main steps: (i) development of the test list through equalization of the intelligibility of test stimuli across the set and (ii) optimization of the test results through maximization of the test sensitivity and specificity. The test had 82.9% sensitivity and 85.9% specificity compared to conventional pure-tone screening, and 83.8% sensitivity and 83.9% specificity to identify individuals with disabling hearing impairment. Results obtained so far showed that the test could be easily performed by adults and older adults in less than one minute per ear and that its results were not influenced by ambient noise (up to 65dBA), suggesting that the test might be a viable method for AHS in clinical as well as non-clinical settings. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ambient seismic noise tomography for exploration seismology at Valhall

Science.gov (United States)

de Ridder, S. A.

2011-12-01

Permanent ocean-bottom cables installed at the Valhall field can repeatedly record high quality active seismic surveys. But in the absence of active seismic shooting, passive data can be recorded and streamed to the platform in real time. Here I studied 29 hours of data using seismic interferometry. I generate omni-directional Scholte-wave virtual-sources at frequencies considered very-low in the exploration seismology community (0.4-1.75 Hz). Scholte-wave group arrival times are inverted using both eikonal tomography and straight-ray tomography. The top 100 m near-surface at Valhall contains buried channels about 100 m wide that have been imaged with active seismic. Images obtained by ASNT using eikonal tomography or straight-ray tomography both contain anomalies that match these channels. When continuous recordings are made in real-time, tomography images of the shallow subsurface can be formed or updated on a daily basis, forming a very low cost near-surface monitoring system using seismic noise.

Attofarad resolution capacitance-voltage measurement of nanometer scale field effect transistors utilizing ambient noise

International Nuclear Information System (INIS)

Gokirmak, Ali; Inaltekin, Hazer; Tiwari, Sandip

2009-01-01

A high resolution capacitance-voltage (C-V) characterization technique, enabling direct measurement of electronic properties at the nanoscale in devices such as nanowire field effect transistors (FETs) through the use of random fluctuations, is described. The minimum noise level required for achieving sub-aF (10 -18 F) resolution, the leveraging of stochastic resonance, and the effect of higher levels of noise are illustrated through simulations. The non-linear ΔC gate-source/drain -V gate response of FETs is utilized to determine the inversion layer capacitance (C inv ) and carrier mobility. The technique is demonstrated by extracting the carrier concentration and effective electron mobility in a nanoscale Si FET with C inv = 60 aF.

Galvanic detection of sulfur dioxide in ambient air at trace levels by anodic oxidation

NARCIS (Netherlands)

Lindqvist, F.

1978-01-01

A continuous method for the measurement of SO2 in ambient air at trace levels is described. The principle of detection is based on the anodic oxidation of SO2 in a galvanic cell. A differential measuring technique with a cell with two anodes and one cathode is used; background and noise current are

Noise exposure and auditory thresholds of German airline pilots: a cross-sectional study.

Science.gov (United States)

Müller, Reinhard; Schneider, Joachim

2017-05-30

The cockpit workplace of airline pilots is a noisy environment. This study examines the hearing thresholds of pilots with respect to ambient noise and communication sound. The hearing of 487 German pilots was analysed by audiometry in the frequency range of 125 Hz-16 kHz in varying age groups. Cockpit noise (free-field) data and communication sound (acoustic manikin) measurements were evaluated. The ambient noise levels in cockpits were found to be between 74 and 80 dB(A), and the sound pressure levels under the headset were found to be between 84 and 88 dB(A).The left-right threshold differences at 3, 4 and 6 kHz show evidence of impaired hearing at the left ear, which worsens by age.In the age groups <40/≥40 years the mean differences at 3 kHz are 2/3 dB, at 4 kHz 2/4 dB and at 6 kHz 1/6 dB.In the pilot group which used mostly the left ear for communication tasks (43 of 45 are in the older age group) the mean difference at 3 kHz is 6 dB, at 4 kHz 7 dB and at 6 kHz 10 dB. The pilots who used the headset only at the right ear also show worse hearing at the left ear of 2 dB at 3 kHz, 3 dB at 4 kHz and at 6 kHz. The frequency-corrected exposure levels under the headset are 7-11 dB(A) higher than the ambient noise with an averaged signal-to-noise ratio for communication of about 10 dB(A). The left ear seems to be more susceptible to hearing loss than the right ear. Active noise reduction systems allow for a reduced sound level for the communication signal below the upper exposure action value of 85 dB(A) and allow for a more relaxed working environment for pilots. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Investigation into the Dependence of Noise Generated By Standing Cars on the Engine Power

Directory of Open Access Journals (Sweden)

Julius Gineika

2012-12-01

Full Text Available Ambient noise harms a number of citizens in Europe. The major sources of environmental noise are that generated by cars in streets, parking lots, railway lines and airports as well as noise from local sources (fans, transformers. According to the methodology for noise measurement, engine testing has been carried out. The conducted analysis has been focused on engine capacity and the distance between vehicles and equipment. Equivalent, maximum and minimum sound levels at different frequencies have been measured accepting that errors may range up to 2 %. Maximum sound level has been reached using the engine of 2000 cm3 petrol capacity. At a half-meter distance, the equivalent sound level reaches 89 dB(A, whereas the noise level decreases moving away from the car. The obtained results of tested cars disclose that according to engine capacity, the majority of the investigated cars are technically faulty and therefore significantly exceed noise levels.Article in Lithuanian

High-resolution surface wave tomography of the European crust and uppermost mantle from ambient seismic noise

Science.gov (United States)

Lu, Yang; Stehly, Laurent; Paul, Anne; AlpArray Working Group

2018-05-01

Taking advantage of the large number of seismic stations installed in Europe, in particular in the greater Alpine region with the AlpArray experiment, we derive a new high-resolution 3-D shear-wave velocity model of the European crust and uppermost mantle from ambient noise tomography. The correlation of up to four years of continuous vertical-component seismic recordings from 1293 broadband stations (10° W-35° E, 30° N-75° N) provides Rayleigh wave group velocity dispersion data in the period band 5-150 s at more than 0.8 million virtual source-receiver pairs. Two-dimensional Rayleigh wave group velocity maps are estimated using adaptive parameterization to accommodate the strong heterogeneity of path coverage. A probabilistic 3-D shear-wave velocity model, including probability densities for the depth of layer boundaries and S-wave velocity values, is obtained by non-linear Bayesian inversion. A weighted average of the probabilistic model is then used as starting model for the linear inversion step, providing the final Vs model. The resulting S-wave velocity model and Moho depth are validated by comparison with previous geophysical studies. Although surface-wave tomography is weakly sensitive to layer boundaries, vertical cross-sections through our Vs model and the associated probability of presence of interfaces display striking similarities with reference controlled-source (CSS) and receiver-function sections across the Alpine belt. Our model even provides new structural information such as a ˜8 km Moho jump along the CSS ECORS-CROP profile that was not imaged by reflection data due to poor penetration across a heterogeneous upper crust. Our probabilistic and final shear wave velocity models have the potential to become new reference models of the European crust, both for crustal structure probing and geophysical studies including waveform modeling or full waveform inversion.

The Effects of Background Noise on the Performance of an Automatic Speech Recogniser

Science.gov (United States)

Littlefield, Jason; HashemiSakhtsari, Ahmad

2002-11-01

Ambient or environmental noise is a major factor that affects the performance of an automatic speech recognizer. Large vocabulary, speaker-dependent, continuous speech recognizers are commercially available. Speech recognizers, perform well in a quiet environment, but poorly in a noisy environment. Speaker-dependent speech recognizers require training prior to them being tested, where the level of background noise in both phases affects the performance of the recognizer. This study aims to determine whether the best performance of a speech recognizer occurs when the levels of background noise during the training and test phases are the same, and how the performance is affected when the levels of background noise during the training and test phases are different. The relationship between the performance of the speech recognizer and upgrading the computer speed and amount of memory as well as software version was also investigated.

Non-stationary least-squares complex decomposition for microseismic noise attenuation

Science.gov (United States)

Chen, Yangkang

2018-06-01

Microseismic data processing and imaging are crucial for subsurface real-time monitoring during hydraulic fracturing process. Unlike the active-source seismic events or large-scale earthquake events, the microseismic event is usually of very small magnitude, which makes its detection challenging. The biggest trouble of microseismic data is the low signal-to-noise ratio issue. Because of the small energy difference between effective microseismic signal and ambient noise, the effective signals are usually buried in strong random noise. I propose a useful microseismic denoising algorithm that is based on decomposing a microseismic trace into an ensemble of components using least-squares inversion. Based on the predictive property of useful microseismic event along the time direction, the random noise can be filtered out via least-squares fitting of multiple damping exponential components. The method is flexible and almost automated since the only parameter needed to be defined is a decomposition number. I use some synthetic and real data examples to demonstrate the potential of the algorithm in processing complicated microseismic data sets.

A reaction cell for ambient pressure soft x-ray absorption spectroscopy

Science.gov (United States)

Castán-Guerrero, C.; Krizmancic, D.; Bonanni, V.; Edla, R.; Deluisa, A.; Salvador, F.; Rossi, G.; Panaccione, G.; Torelli, P.

2018-05-01

We present a new experimental setup for performing X-ray Absorption Spectroscopy (XAS) in the soft X-ray range at ambient pressure. The ambient pressure XAS setup is fully compatible with the ultra high vacuum environment of a synchrotron radiation spectroscopy beamline end station by means of ultrathin Si3N4 membranes acting as windows for the X-ray beam and seal of the atmospheric sample environment. The XAS detection is performed in total electron yield (TEY) mode by probing the drain current from the sample with a picoammeter. The high signal/noise ratio achievable in the TEY mode, combined with a continuous scanning of the X-ray energies, makes it possible recording XAS spectra in a few seconds. The first results show the performance of this setup to record fast XAS spectra from sample surfaces exposed at atmospheric pressure, even in the case of highly insulating samples. The use of a permanent magnet inside the reaction cell enables the measurement of X-ray magnetic circular dichroism at ambient pressure.

Noise thermometer

Energy Technology Data Exchange (ETDEWEB)

Von Brixy, H. [Forschungszentrum Juelich GmbH (Germany); Kakuta, Tsunemi

1996-03-01

The noise thermometry (NT) is a temperature measuring method by which the absolute temperature measurement can be performed with a very high accuracy and without any influence of ambient environments and of the thermal history of its NT sensor (electric resistor). Hence it is quite suitable for application as a standard thermometry to the in-situ temperature calibration of incore thermocouples. The KFA Juelich had played a pioneering role in the development of NT and applied the results successfully to the AVR for testing its feasibility. In this report, all about the NT including its principle, sensor elements and system configurations are presented together with the experiences in the AVR and the results of investigation to apply it to high temperature measurement. The NT can be adopted as a standard method for incore temperature measurement and in situ temperature calibration in the HTTR. (author). 85 refs.

Noise thermometer

International Nuclear Information System (INIS)

Von Brixy, H.; Kakuta, Tsunemi.

1996-03-01

The noise thermometry (NT) is a temperature measuring method by which the absolute temperature measurement can be performed with a very high accuracy and without any influence of ambient environments and of the thermal history of its NT sensor (electric resistor). Hence it is quite suitable for application as a standard thermometry to the in-situ temperature calibration of incore thermocouples. The KFA Juelich had played a pioneering role in the development of NT and applied the results successfully to the AVR for testing its feasibility. In this report, all about the NT including its principle, sensor elements and system configurations are presented together with the experiences in the AVR and the results of investigation to apply it to high temperature measurement. The NT can be adopted as a standard method for incore temperature measurement and in situ temperature calibration in the HTTR. (author). 85 refs

Effect of external pressure environment on the internal noise level due to a source inside a cylindrical tank

Science.gov (United States)

Clevenson, S. A.; Roussos, L. A.

1984-01-01

A small cylindrical tank was used to study the effect on the noise environment within a tank of conditions of atmospheric (sea level) pressure or vacuum environments on the exterior. Experimentally determined absorption coefficients were used to calculate transmission loss, transmissibility coefficients and the sound pressure (noise) level differences in the interior. The noise level differences were also measured directly for the two exterior environments and compared to various analytical approximations with limited agreement. Trend study curves indicated that if the tank transmission loss is above 25 dB, the difference in interior noise level between the vacuum and ambient pressure conditions are less than 2 dB.

FACTORS AFFECTING ROAD TRAFFIC NOISE ANNOYANCE AMONG WHITE-COLLAR EMPLOYEES WORKING IN TEHRAN

Directory of Open Access Journals (Sweden)

*1I. Alimohammadi, 2P. Nassiri, 3M. Azkhosh, 4M. Hoseini

2010-01-01

Full Text Available The effect of personal and attitudinal factors, noise level, hearing status and psychological traits on traffic-related noise annoyance among white-collar employees working in Tehran has been carefully analyzed. This survey has been conducted by interviewing 495 citizens working in non-manufacturing industries in Tehran, using questionnaires, Weinstein noise sensitivity scale, Beck’s depression, Buss and perry’s aggression, Zung’s anxiety, job satisfaction and Eysenc’s personality inventory. These citizens were office workers or store employees. Noise annoyance was determined both by numerical-based questionnaire criterion and by verbal index. Personal information, attitudinal factors and hearing conditions were determined using a general questionnaire. The amount of workplace noise the participants were exposed to was directly measured at their workplaces. It was revealed that among personal factors, age (p=0.030, marital status (p=0.004, residential period (p=0.001 and wealth (p=0.04 were related to noise annoyance. Attitudinal factors including sensitivity to noise (p=0.001, individual’s opinion on the need to control the noise (p=0.000 and individuals’ assessment of the amount of the workplace ambient noise (p= 0.000 were found to have relationship with noise annoyance. No meaningful relationship was seen between the equivalent noise level (p=0.879 and statistical noise level of L90 (p=0.909. The present study revealed that among all effective factors involved in noise annoyance, attitudinal factors had the most significant role in this regard.

Anisotropic full waveform ambient noise and earthquake tomography of the Ontong Java Plateau and surrounding Pacific upper mantle

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Hirsch, A. C.; Savage, B.; Shen, Y.

2017-12-01

The Ontong Java (OJP) and Manihiki plateau (MP) large igneous provinces (LIP) of the Southwest Pacific took shape from a complicated, but poorly understood geological history. Unraveling the formation and deformation of these Pacific LIPs is not straightforward due to limited available data, remote location, and atypical geology. Origin hypotheses include melting of a plume or a fast-spreading triple junction, but distinguishing between these requires a further understanding of 120 Ma of deformation of each LIP. A previous tomographic model of OJP observed highly abnormal Rayleigh shear wave speeds, >4.75km/s, and attributed these to an unusual composition, garnet and clinopyroxene residual from melting pyroxenite entrained within a rising plume. Unfortunately, this model lacks constraints on the horizontally polarized shear wave speeds, SH or Love waves, anisotropy, and attenuation. We therefore perform a transverse-isotropic, scattering-integral, full-waveform tomography between periods of 25 and 200 seconds utilizing both ambient noise empirical Green's functions and seismic data from regional earthquakes. Our tomographic model improves upon previous work using permanent and temporary seismic stations, increased model space, and utilizing three components of seismic data (vertical, radial, and tangential). Included is also an assessment of the anelastic attenuation in the western Pacific using both surface waves and multiple core reflections. Our results will improve the tomographic resolution around OJP and the Pacific upper mantle between 35 and 300 km depth. This improved model will enhance our understanding of the tectonic history of the OJP and MP regions, and the Pacific Indo-Australian plate boundary.

Ambient Seismic Source Inversion in a Heterogeneous Earth: Theory and Application to the Earth's Hum

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Ermert, Laura; Sager, Korbinian; Afanasiev, Michael; Boehm, Christian; Fichtner, Andreas

2017-11-01

The sources of ambient seismic noise are extensively studied both to better understand their influence on ambient noise tomography and related techniques, and to infer constraints on their excitation mechanisms. Here we develop a gradient-based inversion method to infer the space-dependent and time-varying source power spectral density of the Earth's hum from cross correlations of continuous seismic data. The precomputation of wavefields using spectral elements allows us to account for both finite-frequency sensitivity and for three-dimensional Earth structure. Although similar methods have been proposed previously, they have not yet been applied to data to the best of our knowledge. We apply this method to image the seasonally varying sources of Earth's hum during North and South Hemisphere winter. The resulting models suggest that hum sources are localized, persistent features that occur at Pacific coasts or shelves and in the North Atlantic during North Hemisphere winter, as well as South Pacific coasts and several distinct locations in the Southern Ocean in South Hemisphere winter. The contribution of pelagic sources from the central North Pacific cannot be constrained. Besides improving the accuracy of noise source locations through the incorporation of finite-frequency effects and 3-D Earth structure, this method may be used in future cross-correlation waveform inversion studies to provide initial source models and source model updates.

Gestational diabetes mellitus and exposure to ambient air pollution and road traffic noise: A cohort study.

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Pedersen, Marie; Olsen, Sjurdur F; Halldorsson, Thorhallur I; Zhang, Cuilin; Hjortebjerg, Dorrit; Ketzel, Matthias; Grandström, Charlotta; Sørensen, Mette; Damm, Peter; Langhoff-Roos, Jens; Raaschou-Nielsen, Ole

2017-11-01

Road traffic is a main source of air pollution and noise. Both exposures have been associated with type 2 diabetes, but associations with gestational diabetes mellitus (GDM) have been studied less. We aimed to examine single and joint associations of exposure to air pollution and road traffic noise on GDM in a prospective cohort. We identified GDM cases from self-reports and hospital records, using two different criteria, among 72,745 singleton pregnancies (1997-2002) from the Danish National Birth Cohort. We modeled nitrogen dioxide (NO 2 ) and noise from road traffic (L den ) exposure at all pregnancy addresses. According to the two diagnostic criteria: the Danish clinical guidelines, which was our main outcome, and the WHO standard during recruitment period, a total of 565 and 210 women, respectively, had GDM. For both exposures no risk was evident for the common Danish criterion of GDM. A 10-μg/m 3 increase in NO 2 exposure during first trimester was, however, associated with an increased risk of WHO-GDM (adjusted odds ratio (OR)=1.24; 95% confidence interval (CI): 1.03, 1.49). The corresponding OR associated with a 10-dB higher road traffic noise level was 1.15 (0.94 to 1.18). In mutually adjusted models the OR for NO 2 remained similar 1.22 (0.98, 1.53) whereas that for road traffic noise decreased to 1.03 (0.80, 1.32). Significant associations were also observed for exposure averaged over the 2nd and 3rd trimesters and the full pregnancy. No risk was evident for the common Danish criterion of GDM. NO 2 was associated with higher risk for GDM according to the WHO criterion, which might be due to selection bias. Copyright © 2017 Elsevier Ltd. All rights reserved.

Occupational exposure in small and medium scale industry with specific reference to heat and noise

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Lakhwinder Pal Singh

2010-01-01

Full Text Available This study was undertaken to assess heat and noise exposure and occupational safety practices in small and medium scale casting and forging units (SMEs of Northern India. We conducted personal interviews of 350 male workers of these units through a comprehensive questionnaire and collected information on heat and noise exposure, use of protective equipment, sweat loss and water intake, working hour. The ambient wet bulb globe temperature (WBGT index was measured using quest temp 34/36o area heat stress monitor. A-weighted Leq ambient noise was measured using a quest sound level meter "ANSI SI. 43-1997 (R 2002 type-1 model SOUNDPRO SE/DL". We also incorporated OSHA norms for hearing conservation which include - an exchange rate of 5dB(A, criterion level at 90dB(A, criterion time of eight hours, threshold level is equal to 80dB(A, upper limit is equal to 140dB(A and with F/S response rate. Results of the study revealed that occupational heat exposure in melting, casting, forging and punching sections is high compared to ACGIH/NIOSH norms. Ambience noise in various sections like casting / molding, drop forging, cutting presses, punching, grinding and barreling process was found to be more than 90dB(A. About 95% of the workers suffered speech interference where as high noise annoyance was reported by only 20%. Overall, 68% workers were not using any personal protective equipment (PPE. The study concluded that the proportion of SME workers exposed to high level heat stress and noise (60 - 72 hrs/week is high. The workers engaged in forging and grinding sections are more prone to noise induced hearing loss (NIHL at higher frequencies as compared to workers of other sections. It is recommended that there is a strong need to implement the standard of working hours as well as heat stress and noise control measures.

Use of active noise cancellation devices in caregivers in the intensive care unit.

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Akhtar, S; Weigle, C G; Cheng, E Y; Toohill, R; Berens, R J

2000-04-01

Recent development of noise cancellation devices may offer relief from noise in the intensive care unit environment. This study was conducted to evaluate the effect of noise cancellation devices on subjective hearing assessment by caregivers in the intensive care units. Randomized, double-blind. Adult medical intensive care unit and pediatric intensive care unit of a teaching hospital. Caregivers of patients, including nurses, parents, respiratory therapists, and nursing assistants from a medical intensive care unit and pediatric intensive care, were enrolled in the study. Each participant was asked to wear the headphones, functional or nonfunctional noise cancellation devices, for a minimum of 30 mins. Subjective ambient noise level was assessed on a 10-point visual analog scale (VAS) before and during headphone use by each participant. Headphone comfort and the preference of the caregiver to wear the headphone were also evaluated on a 10-point VAS. Simultaneously, objective measurement of noise was done with a sound level meter using the decibel-A scale and at each of nine octave bands at each bedspace. The functional headphones significantly reduced the subjective assessment of noise by 2 (out of 10) VAS points (p noise profiles, based on decibel-A and octave band assessments. Noise cancellation devices improve subjective assessment of noise in caretakers. The benefit of these devices on hearing loss needs further evaluation in caregivers and critically ill patients.

Ambient Modal Testing of the Vestvej Bridge using Random Decrement

DEFF Research Database (Denmark)

Asmussen, J. C.; Brincker, Rune; Rytter, A.

This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...... measurements might have a low signal to noise ratio. Thus, it might be difficult clearly to identify physical modes from the spectral densities. The Random Decrement (RD) technique is another method to perform the data analysis process in the time domain only. It is basically a very simple and very easily...

Ambient Modal Testing of the Vestvej Bridge using Random Decrement

DEFF Research Database (Denmark)

Asmussen, J. C.; Brincker, Rune; Rytter, A.

1998-01-01

This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...... measurements might have a low signal to noise ratio. Thus, it might be difficult clearly to identify physical modes from the spectral densities. The Random Decrement (RD) technique is another method to perform the data analysis process in the time domain only. It is basically a very simple and very easily...

Det Ambiente

DEFF Research Database (Denmark)

Schmidt, Ulrik

Det ambiente er iscenesættelsen af en karakteristisk sanseoplevelse, der er kendetegnet ved fornemmelsen af at være omgivet. I dag bliver begrebet om det ambiente mest anvendt i forbindelse med musikgenren ’ambient musik’. Det ambiente er dog ikke essentielt knyttet til det musikalske, men må...... forstås som et betydeligt bredere fænomen i den moderne æstetiske kultur, der spiller en væsentlig rolle i oplevelsen af moderne transportformer, arkitektur, film, lydkunst, installationskunst og digitale multimedieiscenesættelser. En forståelse af det ambiente er derfor centralt for forståelsen af en...... moderne æstetiseret oplevelseskultur i almindelighed. Da det ambiente ikke hidtil har været gjort til genstand for en mere indgående teoretisk behandling, er der dog stor usikkerhed omkring, hvad fænomenet overhovedet indebærer. Hovedformålet med Det ambiente – Sansning, medialisering, omgivelse er derfor...

More noise, please: How cultural overprinting in the urban environment can be exploited for improved subsurface imaging (Invited)

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Weiss, C. J.

2009-12-01

A long standing issue for geophysical imaging methods revolves around the proper treatment of "noise": Defining what noise is; separating "noise" for "signal"; filtering and suppressing noise; and recently, challenging the prevailing view that noise is a nuisance to see if, instead, it may contribute favorably toward improving subsurface imaging fidelity. This last point is particularly relevant to geophysical imaging in the urban environment where noise sources are abundant, complex, and logistical constraints on geophysical field procedures prohibit a crude "turning up the volume" approach to simply drown out the noise with powerful sources of electromagnetic and seismic energy. In this contribution I explore the concept passive geophysical imaging which uses uncorrelated ambient noise as the source of geophysical imaging energy to be used in the urban environment. Examples will be presented from seismic and ground penetrating radar methods, in addition to new theoretical results bearing on the feasibility of low-frequency electromagnetic induction techniques.

Intelligent Noise Removal from EMG Signal Using Focused Time-Lagged Recurrent Neural Network

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S. N. Kale

2009-01-01

Full Text Available Electromyography (EMG signals can be used for clinical/biomedical application and modern human computer interaction. EMG signals acquire noise while traveling through tissue, inherent noise in electronics equipment, ambient noise, and so forth. ANN approach is studied for reduction of noise in EMG signal. In this paper, it is shown that Focused Time-Lagged Recurrent Neural Network (FTLRNN can elegantly solve to reduce the noise from EMG signal. After rigorous computer simulations, authors developed an optimal FTLRNN model, which removes the noise from the EMG signal. Results show that the proposed optimal FTLRNN model has an MSE (Mean Square Error as low as 0.000067 and 0.000048, correlation coefficient as high as 0.99950 and 0.99939 for noise signal and EMG signal, respectively, when validated on the test dataset. It is also noticed that the output of the estimated FTLRNN model closely follows the real one. This network is indeed robust as EMG signal tolerates the noise variance from 0.1 to 0.4 for uniform noise and 0.30 for Gaussian noise. It is clear that the training of the network is independent of specific partitioning of dataset. It is seen that the performance of the proposed FTLRNN model clearly outperforms the best Multilayer perceptron (MLP and Radial Basis Function NN (RBF models. The simple NN model such as the FTLRNN with single-hidden layer can be employed to remove noise from EMG signal.

Ocean Basin Impact of Ambient Noise on Marine Mammal Detectability, Distribution, and Acoustic Communication

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2015-09-30

soundscapes , and unit of analysis methodology. The study has culminated in a complex analysis of all environmental factors that could be predictors of...regional soundscapes . To build the correlation matrices from ambient sound recordings, the raw data was first converted into a series of sound...sounds. To compare two different soundscape time periods, the correlation matrices for the two periods were then subtracted from each other

The Global Detection Capability of the IMS Seismic Network in 2013 Inferred from Ambient Seismic Noise Measurements

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Gaebler, P. J.; Ceranna, L.

2016-12-01

All nuclear explosions - on the Earth's surface, underground, underwater or in the atmosphere - are banned by the Comprehensive Nuclear-Test-Ban Treaty (CTBT). As part of this treaty, a verification regime was put into place to detect, locate and characterize nuclear explosion testings at any time, by anyone and everywhere on the Earth. The International Monitoring System (IMS) plays a key role in the verification regime of the CTBT. Out of the different monitoring techniques used in the IMS, the seismic waveform approach is the most effective technology for monitoring nuclear underground testing and to identify and characterize potential nuclear events. This study introduces a method of seismic threshold monitoring to assess an upper magnitude limit of a potential seismic event in a certain given geographical region. The method is based on ambient seismic background noise measurements at the individual IMS seismic stations as well as on global distance correction terms for body wave magnitudes, which are calculated using the seismic reflectivity method. From our investigations we conclude that a global detection threshold of around mb 4.0 can be achieved using only stations from the primary seismic network, a clear latitudinal dependence for the detection thresholdcan be observed between northern and southern hemisphere. Including the seismic stations being part of the auxiliary seismic IMS network results in a slight improvement of global detection capability. However, including wave arrivals from distances greater than 120 degrees, mainly PKP-wave arrivals, leads to a significant improvement in average global detection capability. In special this leads to an improvement of the detection threshold on the southern hemisphere. We further investigate the dependence of the detection capability on spatial (latitude and longitude) and temporal (time) parameters, as well as on parameters such as source type and percentage of operational IMS stations.

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Adverse Birth Outcomes.

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Nieuwenhuijsen, Mark J; Ristovska, Gordana; Dadvand, Payam

2017-10-19

Introduction: Three recent systematic reviews suggested a relationship between noise exposure and adverse birth outcomes. The aim of this review was to evaluate the evidence for the World Health Organization (WHO) noise guidelines and conduct an updated systematic review of environmental noise, specifically aircraft and road traffic noise and birth outcomes, such as preterm birth, low birth weight, being small for gestational age and congenital malformations. Materials and methods : We reviewed again all the papers on environmental noise and birth outcomes included in the previous three systematic reviews and conducted a systematic search on noise and birth outcomes to update previous reviews. Web of Science, PubMed and Embase electronic databases were searched for papers published between June 2014 (end date of previous systematic review) and December 2016 using a list of specific search terms. Studies were also screened in the reference list of relevant reviews/articles. Further inclusion and exclusion criteria for the studies provided by the WHO expert group were applied. Risk of bias was assessed according to criteria from the Newcastle-Ottawa quality assessment scale for case-control and cohort studies. Finally, we applied the GRADE principles to our systematic review in a reproducible and appropriate way for judgment about quality of evidence. Results: In total, 14 studies are included in this review, six studies on aircraft noise and birth outcomes, five studies (two with more or less the same population) on road traffic noise and birth outcomes and three related studies on total ambient noise that is likely to be mostly traffic noise that met the criteria. The number of studies on environmental noise and birth outcomes is small and the quality of evidence generally ranges from very low to low, particularly in case of the older studies. The quality is better for the more recent traffic noise and birth outcomes studies. As there were too few studies, we did

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Adverse Birth Outcomes

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Mark J. Nieuwenhuijsen

2017-10-01

Full Text Available Introduction: Three recent systematic reviews suggested a relationship between noise exposure and adverse birth outcomes. The aim of this review was to evaluate the evidence for the World Health Organization (WHO noise guidelines and conduct an updated systematic review of environmental noise, specifically aircraft and road traffic noise and birth outcomes, such as preterm birth, low birth weight, being small for gestational age and congenital malformations. Materials and methods: We reviewed again all the papers on environmental noise and birth outcomes included in the previous three systematic reviews and conducted a systematic search on noise and birth outcomes to update previous reviews. Web of Science, PubMed and Embase electronic databases were searched for papers published between June 2014 (end date of previous systematic review and December 2016 using a list of specific search terms. Studies were also screened in the reference list of relevant reviews/articles. Further inclusion and exclusion criteria for the studies provided by the WHO expert group were applied. Risk of bias was assessed according to criteria from the Newcastle-Ottawa quality assessment scale for case-control and cohort studies. Finally, we applied the GRADE principles to our systematic review in a reproducible and appropriate way for judgment about quality of evidence. Results: In total, 14 studies are included in this review, six studies on aircraft noise and birth outcomes, five studies (two with more or less the same population on road traffic noise and birth outcomes and three related studies on total ambient noise that is likely to be mostly traffic noise that met the criteria. The number of studies on environmental noise and birth outcomes is small and the quality of evidence generally ranges from very low to low, particularly in case of the older studies. The quality is better for the more recent traffic noise and birth outcomes studies. As there were too few

Combined Exposures: An update from the International comission on biological effects of noise

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Tony Leroux

2012-01-01

Full Text Available International Commission on Biological Effects of Noise (ICBEN Team 8 deals with the effects of combined "agents" in the urban and work place settings. Results presented at the ICBEN conference indicate that some pesticides, more specifically the organophosphates, and a wider range of industrial chemicals are harmful to the auditory system at concentrations often found in occupational settings. Effects of occupational noise on hearing are exacerbated by toluene and possibly by carbon monoxide. Several of the chemicals studied found to be potentially toxic not only to hair cells in the cochlea but also to the auditory nerve. In urban environments, team 8 focuses on additive and synergetic effects of ambient stressors. It was argued that noise policies need to pay attention to grey areas with intermediate noise levels. Noteworthy is also stronger reactions to vibrations experienced in the evening and during the night. An innovative event-based model for sound perception was presented.

REVIEW ARTICLE: A comparison of site response techniques using earthquake data and ambient seismic noise analysis in the large urban areas of Santiago de Chile

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Pilz, Marco; Parolai, Stefano; Leyton, Felipe; Campos, Jaime; Zschau, Jochen

2009-08-01

Situated in an active tectonic region, Santiago de Chile, the country's capital with more than six million inhabitants, faces tremendous earthquake risk. Macroseismic data for the 1985 Valparaiso event show large variations in the distribution of damage to buildings within short distances, indicating strong effects of local sediments on ground motion. Therefore, a temporary seismic network was installed in the urban area for recording earthquake activity and a study was carried out aiming to estimate site amplification derived from horizontal-to-vertical (H/V) spectral ratios from earthquake data (EHV) and ambient noise (NHV), as well as using the standard spectral ratio (SSR) technique with a nearby reference station located on igneous rock. The results lead to the following conclusions: (1) The analysis of earthquake data shows significant dependence on the local geological structure with respect to amplitude and duration. (2) An amplification of ground motion at frequencies higher than the fundamental one can be found. This amplification would not be found when looking at NHV ratios alone. (3) The analysis of NHV spectral ratios shows that they can only provide a lower bound in amplitude for site amplification. (4) P-wave site responses always show lower amplitudes than those derived by S waves, and sometimes even fail to provide some frequencies of amplification. (5) No variability in terms of time and amplitude is observed in the analysis of the H/V ratio of noise. (6) Due to the geological conditions in some parts of the investigated area, the fundamental resonance frequency of a site is difficult to estimate following standard criteria proposed by the SESAME consortium, suggesting that these are too restrictive under certain circumstances.

Noise suppression by noise

OpenAIRE

Vilar, J. M. G. (José M. G.), 1972-; Rubí Capaceti, José Miguel

2001-01-01

We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.

Anatomy of the high-frequency ambient seismic wave field at the TCDP borehole

Science.gov (United States)

Hillers, G.; Campillo, M.; Lin, Y.-Y.; Ma, K.-F.; Roux, P.

2012-06-01

The Taiwan Chelungpu-fault Drilling Project (TCDP) installed a vertical seismic array between 950 and 1270 m depth in an active thrust fault environment. In this paper we analyze continuous noise records of the TCDP array between 1 and 16 Hz. We apply multiple array processing and noise correlation techniques to study the noise source process, properties of the propagation medium, and the ambient seismic wave field. Diurnal amplitude and slowness patterns suggest that noise is generated by cultural activity. The vicinity of the recording site to the excitation region, indicated by a narrow azimuthal distribution of propagation directions, leads to a predominant ballistic propagation regime. This is evident from the compatibility of the data with an incident plane wave model, polarized direct arrivals of noise correlation functions, and the asymmetric arrival shape. Evidence for contributions from scattering comes from equilibrated earthquake coda energy ratios, the frequency dependent randomization of propagation directions, and the existence of correlation coda waves. We conclude that the ballistic and scattered propagation regime coexist, where the first regime dominates the records, but the second is weaker yet not negligible. Consequently, the wave field is not equipartitioned. Correlation signal-to-noise ratios indicate a frequency dependent noise intensity. Iterations of the correlation procedure enhance the signature of the scattered regime. Discrepancies between phase velocities estimated from correlation functions and in-situ measurements are associated with the array geometry and its relative orientation to the predominant energy flux. The stability of correlation functions suggests their applicability in future monitoring efforts.

First to Flush: The Effects of Ambient Noise on Songbird Flight Initiation Distances and Implications for Human Experiences with Nature

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Alissa R. Petrelli

2017-06-01

Full Text Available Throughout the world, birds represent the primary type of wildlife that people experience on a daily basis. However, a growing body of evidence suggests that alterations to the acoustic environment can negatively affect birds as well as humans in a variety of ways, and altered acoustics from noise pollution has the potential to influence human interactions with wild birds. Birds respond to approaching humans in a manner analogous to approaching predators, but the context of the interaction can also greatly influence the distance at which a bird initiates flight or escape behavior (i.e., flight initiation distance or FID. Here, we hypothesized that reliance on different sensory modalities to balance foraging and threat detection can influence how birds respond to approaching threats in the presence of background noise. We surveyed 12 songbird species in California and Wyoming and categorized each species into one of three foraging guilds: ground foragers, canopy gleaners, and hawking flycatchers and predicted FIDs to decrease, remain the same and increase with noise exposure, respectively. Contrary to expectations, the canopy gleaning and flycatching guilds exhibited mixed responses, with some species exhibiting unchanged FIDs with noise while others exhibited increased FIDs with noise. However, FIDs of all ground foraging species and one canopy gleaner decreased with noise levels. Additionally, we found no evidence of phylogenetic structure among species' mean FID responses and only weak phylogenetic structure for the relationship between FIDs and noise levels. Although our results provide mixed support for foraging strategy as a predictor of bird response to noise, our finding that most of the species we surveyed have shorter FIDs with increases in noise levels suggest that human observers may be able to approach ground foraging species more closely under noisy conditions. From an ecological perspective, however, it remains unclear whether

Long-termexposure to road traffic noise, ambient air pollution, and cardiovascular risk factors in the HUNT and lifelines cohorts

NARCIS (Netherlands)

Cai, Yutong; Hansell, Anna L.; Blangiardo, Marta; Burton, Paul R.; de Hoogh, Kees; Doiron, Dany; Fortier, Isabel; Gulliver, John; Hveem, Kristian; Mbatchou, Stéphane; Morley, DavidW.; Stolk, Ronald P.; Zijlema, Wilma L.; Elliott, Paul; Hodgson, Susan

2017-01-01

Aims: Blood biochemistry may provide information on associations between road traffic noise, air pollution, and cardiovascular disease risk. We evaluated this in two large European cohorts (HUNT3, Lifelines). Methods and results: Road traffic noise exposure was modelled for 2009 using a simplified

Influence of urban morphology on total noise pollution: multifractal description.

Science.gov (United States)

Ariza-Villaverde, Ana B; Jiménez-Hornero, Francisco J; Gutiérrez De Ravé, Eduardo

2014-02-15

Exposure to ambient noise levels above 65 dB can cause public health problems. The spatial distribution of this kind of pollution is linked to various elements which make up the urban form, such as construction density, the existence of open spaces and the shape and physical position of buildings. Since urban morphology displays multifractal behaviour, the present research studies for the first time the relationship between total noise pollution and urban features, such as street width and building height by means of a joint multifractal spectrum in two neighbourhoods of the city of Cordoba (Andalusia, Spain). According to the results, the joint multifractal spectrum reveals a positive correlation between the total noise pollution and the street width to building height ratio, this being more evident when urban morphology is regular. The information provided by the multifractal analysis completes the description obtained by using urban indexes and landscape metrics and might be useful for urban planning once the linkage between both frameworks has been done. Copyright © 2013 Elsevier B.V. All rights reserved.

Periodismo ambiental

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Lucía Lemos

2015-01-01

Full Text Available Los periodistas toman el tema del medio ambiente cada vez más en serio. El uso de temas relacionados con el medio ambiente, debe estar ligado al análisis socio-económico y a las posibilidades de comunicación y educación de diferentes regiones del mundo. A continuación se presenta un resumen de la situación ambiental, las acciones de prensa y comunicación que se llevan a cabo en América Central (Panamá, El Salvador, Costa Rica y en Sudamérica Brasil,Colombia, Chile, México, y Perú. Se concluye en la necesidad de formar hábitos ecológicos. Los comunicadores deben presentar soluciones a los problemas, fomentar campañas comunes, compartir información y velar por el ambiente ambiente para que las generaciones futuras no tengan que perecer.

Radiation and noise exposures elicit biological and behavioural effects in the rat

International Nuclear Information System (INIS)

Trivedi, A.; Michaud, D.S.; Ferrarotto, C.; Keith, S.E.; Miller, S.M.; Bowers, W.J.; Kumarathsan, P.

2003-01-01

The presence of radiation and noise is ubiquitous in a living environment. Therefore, the effect of these sources alone and together on the body has the potential for public health consequences. We have examined the physiological and behavioural effects of separate and combined exposures to radiation and noise in adult male Sprague-Dawley rats. For three weeks animals were exposed to the following conditions: 1) daily exposure to x-rays (cumulative whole body dose = 5Gy); 2) random intermittent noise band-limited between 400Hz-20 kHz; 2 h/day 90 dB lin and 3) combined exposures. Control animals were housed under ambient noise conditions (∼ 55-60 dBA) and sham-exposed to x-rays. The mean body weight gain (initial avg. ∼ 250g) appeared to be affected by the treatments; control (88g); noise (76g); radiation (60g) and noise/radiation (43g). Compared to control and noise only animals, plasma levels of 8-hydroxy-2'-deoxyguanosine increased significantly in animals exposed to both radiation alone and radiation with noise, while big-endothelin-1 was significantly reduced in both groups exposed to radiation. There were no noticeable changes in the levels of adrenocorticotrophic hormone and the variability in plasma norepinephrine and epinephrine precluded conclusions with respect to changes in sympathetic activity. No groups showed any consistent changes in plasma levels of interleukin-1, corticotrophin releasing hormone or urocortin. Plasma corticosterone increased in animals exposed to only noise, but this hormone was significantly reduced in animals exposed to only radiation. Behavioural endpoints revealed that startle amplitude (105dB) was highest in animals exposed to only noise and lowest in animals exposed to both noise and radiation, compared to the control animals. These results suggest that radiation exposure might alter systems activated by stressor exposure and/or act independently to influence health outcomes

Ambient seismic noise as an interesting indirect cue for the Cerithidea decollata migrations

Science.gov (United States)

Pazzi, Veronica; Lotti, Alessia

2017-04-01

Presence or absence of water, food availability, capability of avoiding predation, and body temperature are constantly changing according to the tidal excursion. In fact, more than the diurnal light-dark variation, tide is shaping the whole intertidal animal life. Therefore, physiological and behavioural systems exist to reduce the stress that the intertidal fauna may face during the unsuitable tidal phase. Cerithidea decollata is a common western Indian Ocean mangrove gastropod. It feeds on the ground at low tide, and climbs the trees two/three hours before the water arrival to avoid submersion. In spite of the irregular East African tidal pattern, it also regularly settles on trunks roughly 40 cm above the maximum level of the incoming tide. Migrations usually take place about twice a day unless at Neap Tide, when snails may remain on the dry ground. Past experiments showed that a biological clock cannot account for water level foreseeing, nor direct visual cues or chemical information from the water itself or from previous migrations have been detected. On the other hand, tidal gravity variations can be felt by the snails. Moreover, other indirect cues could be hypothesize related to a) the oceanic waves reaching the coast and the barrier reef (seismic noise), or b) the changes in ground resistivity (self potential) caused by the sea water moving close. To verify these hypotheses, an integrated geophysical survey (single-station seismic noise and self potential survey) was carried out at Mida Creek (Kenya) to characterize the local seismic wavefield in terms of its amplitude and to measure the temporal variations of the electric potential field. Final goal was to verify whether a correlation exists between the time evolution of these phenomena and the snail movements. Here we present the first results of the seismic noise measurements. Data were acquired by means of a single station all-in-one 3-directional 24-bit digital tromometer equipped with 4.5 Hz

Influence of traffic-related noise and air pollution on self-reported fatigue.

Science.gov (United States)

Jazani, Reza Khani; Saremi, Mahnaz; Rezapour, Tara; Kavousi, Amir; Shirzad, Hadi

2015-01-01

A growing body of evidence suggests that exposure to environmental pollutions is related to health problems. It is, however, questionable whether this condition affects working performance in occupational settings. The aim of this study is to determine the predictive value of age as well as traffic related air and noise pollutions for fatigue. 246 traffic officers participated in this study. Air pollution data were obtained from the local Air Quality Control Company. A sound level meter was used for measuring ambient noise. Fatigue was evaluated by the MFI-20 questionnaire. The general and physical scales showed the highest, while the reduced activity scale showed the lowest level of fatigue. Age had an independent direct effect on reduced activity and physical fatigue. The average of daytime equivalent noise level was between 71.63 and 88.51 dB(A). In the case of high noise exposure, older officers feel more fatigue than younger ones. Exposure to PM10 and O3 resulted in general and physical fatigue. Complex Interactions between SO2, CO and NO2 were found. Exposure to noise and some components of air pollution, especially O3 and PM10, increases fatigue. The authorities should adopt and rigorously implement environmental protection policies in order to protect people.

The Influence of Changing Sea Conditions on Shipping Noise, Including Effects of Wind, Fish and Climate Change

NARCIS (Netherlands)

Ainslie, M.A.; Jong, C.A.F. de

2011-01-01

Early human interest in ambient noise in the sea, especially during and after the Second World War, resulted from its effect on limiting the performance of military search sonar [Urick 1983]. While that interest continues, it is now accompanied by non-military uses of underwater sound, such as

Pileup noise behavior and corrections in the ATLAS EMCal

CERN Document Server

Seneca, Jordan Anders Leo

2017-01-01

In this note, the pile-up influence on the energy resolution of the ATLAS LAr EMCal expected until the end of run 2 is explored, with the supercluster algorithm. The pile-up noise is extracted for various η-regions and electron energies, and found to match the expected behavior. An attempt is then made at improving the energy resolution using the ambient energy density and pileup tracks using two methods for finding correlations. The corrections yield no significant improvement to the energy resolution due to small correlations.

Effects of measurement noise on modal parameter identification

International Nuclear Information System (INIS)

Dorvash, S; Pakzad, S N

2012-01-01

In the past decade, much research has been conducted on data-driven structural health monitoring (SHM) algorithms with use of sensor measurements. A fundamental step in this SHM application is to identify the dynamic characteristics of structures. Despite the significant efforts devoted to development and enhancement of the modal parameter identification algorithms, there are still substantial uncertainties in the results obtained in real-life deployments. One of the sources of uncertainties in the results is the existence of noise in the measurement data. Depending on the subsequent application of the system identification, the level of uncertainty in the results and, consequently, the level of noise contamination can be very important. As an effort towards understanding the effect of measurement noise on the modal identification, this paper presents parameters that quantify the effects of measurement noise on the modal identification process and determine their influence on the accuracy of results. The performance of these parameters is validated by a numerically simulated example. They are then used to investigate the accuracy of identified modal properties of the Golden Gate Bridge using ambient data collected by wireless sensors. The vibration monitoring tests of the Golden Gate Bridge provided two synchronized data sets collected by two different sensor types. The influence of the sensor noise level on the accuracy of results is investigated throughout this work and it is shown that high quality sensors provide more accurate results as the physical contribution of response in their measured data is significantly higher. Additionally, higher purity and consistency of modal parameters, identified by higher quality sensors, is observed in the results. (paper)

A neural network for noise correlation classification

Science.gov (United States)

Paitz, Patrick; Gokhberg, Alexey; Fichtner, Andreas

2018-02-01

We present an artificial neural network (ANN) for the classification of ambient seismic noise correlations into two categories, suitable and unsuitable for noise tomography. By using only a small manually classified data subset for network training, the ANN allows us to classify large data volumes with low human effort and to encode the valuable subjective experience of data analysts that cannot be captured by a deterministic algorithm. Based on a new feature extraction procedure that exploits the wavelet-like nature of seismic time-series, we efficiently reduce the dimensionality of noise correlation data, still keeping relevant features needed for automated classification. Using global- and regional-scale data sets, we show that classification errors of 20 per cent or less can be achieved when the network training is performed with as little as 3.5 per cent and 16 per cent of the data sets, respectively. Furthermore, the ANN trained on the regional data can be applied to the global data, and vice versa, without a significant increase of the classification error. An experiment where four students manually classified the data, revealed that the classification error they would assign to each other is substantially larger than the classification error of the ANN (>35 per cent). This indicates that reproducibility would be hampered more by human subjectivity than by imperfections of the ANN.

An experimental test of noise-dependent voice amplitude regulation in Cope's grey treefrog (Hyla chrysoscelis).

Science.gov (United States)

Love, Elliot K; Bee, Mark A

2010-09-01

One strategy for coping with the constraints on acoustic signal reception posed by ambient noise is to signal louder as noise levels increase. Termed the 'Lombard effect', this reflexive behaviour is widespread among birds and mammals and occurs with a diversity of signal types, leading to the hypothesis that voice amplitude regulation represents a general vertebrate mechanism for coping with environmental noise. Support for this evolutionary hypothesis, however, remains limited due to a lack of studies in taxa other than birds and mammals. Here, we report the results of an experimental test of the hypothesis that male grey treefrogs increase the amplitude of their advertisement calls in response to increasing levels of chorus-shaped noise. We recorded spontaneously produced calls in quiet and in the presence of noise broadcast at sound pressure levels ranging between 40 dB and 70 dB. While increasing noise levels induced predictable changes in call duration and rate, males did not regulate call amplitude. These results do not support the hypothesis that voice amplitude regulation is a generic vertebrate mechanism for coping with noise. We discuss the possibility that intense sexual selection and high levels of competition for mates in choruses place some frogs under strong selection to call consistently as loudly as possible.

Effects of background noise on total noise annoyance

Science.gov (United States)

Willshire, K. F.

1987-01-01

Two experiments were conducted to assess the effects of combined community noise sources on annoyance. The first experiment baseline relationships between annoyance and noise level for three community noise sources (jet aircraft flyovers, traffic and air conditioners) presented individually. Forty eight subjects evaluated the annoyance of each noise source presented at four different noise levels. Results indicated the slope of the linear relationship between annoyance and noise level for the traffic noise was significantly different from that of aircraft and of air conditioner noise, which had equal slopes. The second experiment investigated annoyance response to combined noise sources, with aircraft noise defined as the major noise source and traffic and air conditioner noise as background noise sources. Effects on annoyance of noise level differences between aircraft and background noise for three total noise levels and for both background noise sources were determined. A total of 216 subjects were required to make either total or source specific annoyance judgements, or a combination of the two, for a wide range of combined noise conditions.

Maximizing noise energy for noise-masking studies.

Science.gov (United States)

Jules Étienne, Cédric; Arleo, Angelo; Allard, Rémy

2017-08-01

Noise-masking experiments are widely used to investigate visual functions. To be useful, noise generally needs to be strong enough to noticeably impair performance, but under some conditions, noise does not impair performance even when its contrast approaches the maximal displayable limit of 100 %. To extend the usefulness of noise-masking paradigms over a wider range of conditions, the present study developed a noise with great masking strength. There are two typical ways of increasing masking strength without exceeding the limited contrast range: use binary noise instead of Gaussian noise or filter out frequencies that are not relevant to the task (i.e., which can be removed without affecting performance). The present study combined these two approaches to further increase masking strength. We show that binarizing the noise after the filtering process substantially increases the energy at frequencies within the pass-band of the filter given equated total contrast ranges. A validation experiment showed that similar performances were obtained using binarized-filtered noise and filtered noise (given equated noise energy at the frequencies within the pass-band) suggesting that the binarization operation, which substantially reduced the contrast range, had no significant impact on performance. We conclude that binarized-filtered noise (and more generally, truncated-filtered noise) can substantially increase the energy of the noise at frequencies within the pass-band. Thus, given a limited contrast range, binarized-filtered noise can display higher energy levels than Gaussian noise and thereby widen the range of conditions over which noise-masking paradigms can be useful.

Active Noise Control for Dishwasher noise

Science.gov (United States)

Lee, Nokhaeng; Park, Youngjin

2016-09-01

The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.

A First Layered Crustal Velocity Model for the Western Solomon Islands: Inversion of Measured Group Velocity of Surface Waves using Ambient Noise Cross-Correlation

Science.gov (United States)

Ku, C. S.; Kuo, Y. T.; Chao, W. A.; You, S. H.; Huang, B. S.; Chen, Y. G.; Taylor, F. W.; Yih-Min, W.

2017-12-01

Two earthquakes, MW 8.1 in 2007 and MW 7.1 in 2010, hit the Western Province of Solomon Islands and caused extensive damage, but motivated us to set up the first seismic network in this area. During the first phase, eight broadband seismic stations (BBS) were installed around the rupture zone of 2007 earthquake. With one-year seismic records, we cross-correlated the vertical component of ambient noise recorded in our BBS and calculated Rayleigh-wave group velocity dispersion curves on inter-station paths. The genetic algorithm to invert one-dimensional crustal velocity model is applied by fitting the averaged dispersion curves. The one-dimensional crustal velocity model is constituted by two layers and one half-space, representing the upper crust, lower crust, and uppermost mantle respectively. The resulted thickness values of the upper and lower crust are 6.4 and 14.2 km, respectively. Shear-wave velocities (VS) of the upper crust, lower crust, and uppermost mantle are 2.53, 3.57 and 4.23 km/s with the VP/VS ratios of 1.737, 1.742 and 1.759, respectively. This first layered crustal velocity model can be used as a preliminary reference to further study seismic sources such as earthquake activity and tectonic tremor.

Towards a practical Johnson noise thermometer for long-term measurements in harsh environments

International Nuclear Information System (INIS)

Greenen, Adam; Pearce, Jonathan; Cruickshank, David; Bramley, Paul

2015-01-01

The impact of mechanical and chemical changes in conventional sensors such as thermocouples and resistance thermometers can be avoided by instead using temperature sensors based on fundamental thermometry. A prime example of this is Johnson noise thermometry, which is based on measurement of the fluctuations in the voltage of a resistor arising from thermal motion of charge carriers - i.e. the 'Johnson noise'. A Johnson noise thermometer never needs calibration and is insensitive to the condition of the sensor material. It is therefore ideally suited to long-term temperature measurements in harsh environments, such as nuclear reactor coolant circuits, in-pile measurements, nuclear waste management and storage, and severe accident monitoring. There have been a number of previous attempts to develop a Johnson noise thermometer for the nuclear industry, but none have reached commercial exploitation because of technical problems in practical implementation. The main challenge is to extract the tiny Johnson noise signal from ambient electrical noise influences, both from the internal amplification electronics, and from external electrical noise sources. Recent advances in electronics technology and digital signal processing techniques have opened up new possibilities for developing a viable, practical Johnson noise thermometer. We describe a project funded by the UK Technology Strategy Board (now Innovate UK) 'Developing the nuclear supply chain' call, currently underway, to develop a practical Johnson noise thermometer that makes use of innovative electronics for ultralow noise amplification and signal processing. The new electronics technology has the potential to help overcome the problems encountered with previous attempts at constructing a practical Johnson noise thermometer. An outline of the new developments is presented, together with an overview of the current status of the project. (authors)

Noise levels of neonatal high-flow nasal cannula devices--an in-vitro study.

Science.gov (United States)

König, Kai; Stock, Ellen L; Jarvis, Melanie

2013-01-01

Excessive ambient noise levels have been identified as a potential risk factor for adverse outcome in very preterm infants. Noise level measurements for continuous positive airway pressure (CPAP) devices demonstrated that these constantly exceed current recommendations. The use of high-flow nasal cannula (HFNC) as an alternative non-invasive ventilation modality has become more popular in recent years in neonatal care. To study noise levels of two HFNC devices commonly used in newborns. As a comparison, noise levels of a continuous flow CPAP device were also studied. In-vitro study. The noise levels of two contemporary HFNC devices (Fisher & Paykel NHF™ and Vapotherm Precision Flow®) and one CPAP device (Dräger Babylog® 8000 plus) were measured in the oral cavity of a newborn manikin in an incubator in a quiet environment. HFNC flows of 4-8 l/min and CPAP pressures of 4-8 cm H2O were applied. The CPAP flow was set at 8 l/min as per unit practice. Vapotherm HFNC generated the highest noise levels, measuring 81.2-91.4 dB(A) with increasing flow. Fisher & Paykel HFNC noise levels were between 78.8 and 81.2 dB(A). The CPAP device generated the lowest noise levels between 73.9 and 77.4 dB(A). Both HFNC devices generated higher noise levels than the CPAP device. All noise levels were far above current recommendations of the American Academy of Pediatrics. In light of the long duration of non-invasive respiratory support of very preterm infants, less noisy devices are required to prevent the potentially adverse effects of continuing excessive noise exposure in the neonatal intensive care unit. Copyright © 2013 S. Karger AG, Basel.

Towards a practical Johnson noise thermometer for long-term measurements in harsh environments

Energy Technology Data Exchange (ETDEWEB)

Greenen, Adam; Pearce, Jonathan [National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, (United Kingdom); Cruickshank, David; Bramley, Paul [Metrosol Limited, Plum Park Estate, Watling Street, Paulerspury, Northamptonshire, NN12 6LQ, (United Kingdom)

2015-07-01

The impact of mechanical and chemical changes in conventional sensors such as thermocouples and resistance thermometers can be avoided by instead using temperature sensors based on fundamental thermometry. A prime example of this is Johnson noise thermometry, which is based on measurement of the fluctuations in the voltage of a resistor arising from thermal motion of charge carriers - i.e. the 'Johnson noise'. A Johnson noise thermometer never needs calibration and is insensitive to the condition of the sensor material. It is therefore ideally suited to long-term temperature measurements in harsh environments, such as nuclear reactor coolant circuits, in-pile measurements, nuclear waste management and storage, and severe accident monitoring. There have been a number of previous attempts to develop a Johnson noise thermometer for the nuclear industry, but none have reached commercial exploitation because of technical problems in practical implementation. The main challenge is to extract the tiny Johnson noise signal from ambient electrical noise influences, both from the internal amplification electronics, and from external electrical noise sources. Recent advances in electronics technology and digital signal processing techniques have opened up new possibilities for developing a viable, practical Johnson noise thermometer. We describe a project funded by the UK Technology Strategy Board (now Innovate UK) 'Developing the nuclear supply chain' call, currently underway, to develop a practical Johnson noise thermometer that makes use of innovative electronics for ultralow noise amplification and signal processing. The new electronics technology has the potential to help overcome the problems encountered with previous attempts at constructing a practical Johnson noise thermometer. An outline of the new developments is presented, together with an overview of the current status of the project. (authors)

Spatial Statistics of Deep-Water Ambient Noise; Dispersion Relations for Sound Waves and Shear Waves

Science.gov (United States)

2015-09-30

bi-linear hydrophone 8 array to locate biological sound sources on a coral reef ”, J. Acoust. Soc. Am. 137, 30-41 (2015) [published, refereed]. 3...Friedlander, A. K. Gregg, S. A. Sandin and M. J. Buckingham, “The origins of ambient biological sound from coral reef ecosystems in the Line Islands...descending under gravity and, after releasing a drop weight at a pre-assigned depth, returning to the surface under buoyancy. Throughout the descent and

Locating scatterers while drilling using seismic noise due to tunnel boring machine

Science.gov (United States)

Harmankaya, U.; Kaslilar, A.; Wapenaar, K.; Draganov, D.

2018-05-01

Unexpected geological structures can cause safety and economic risks during underground excavation. Therefore, predicting possible geological threats while drilling a tunnel is important for operational safety and for preventing expensive standstills. Subsurface information for tunneling is provided by exploratory wells and by surface geological and geophysical investigations, which are limited by location and resolution, respectively. For detailed information about the structures ahead of the tunnel face, geophysical methods are applied during the tunnel-drilling activity. We present a method inspired by seismic interferometry and ambient-noise correlation that can be used for detecting scatterers, such as boulders and cavities, ahead of a tunnel while drilling. A similar method has been proposed for active-source seismic data and validated using laboratory and field data. Here, we propose to utilize the seismic noise generated by a Tunnel Boring Machine (TBM), and recorded at the surface. We explain our method at the hand of data from finite-difference modelling of noise-source wave propagation in a medium where scatterers are present. Using the modelled noise records, we apply cross-correlation to obtain correlation gathers. After isolating the scattered arrivals in these gathers, we cross-correlate again and invert for the correlated traveltime to locate scatterers. We show the potential of the method for locating the scatterers while drilling using noise records due to TBM.

Atmosphere and Ambient Space

DEFF Research Database (Denmark)

Schmidt, Ulrik

Atmosphere and Ambient Space This paper explores the relation between atmosphere and ambient space. Atmosphere and ambient space share many salient properties. They are both ontologically indeterminate, constantly varying and formally diffuse and they are both experienced as a subtle, non......-signifying property of a given space. But from a certain point of view, the two concepts also designate quite dissimilar experiences of space. To be ’ambient’ means to surround. Accordingly, ambient space is that space, which surrounds something or somebody. (Gibson 1987: 65) Since space is essentially...... of a surrounding character, all space can thus be described as having a fundamentally ambient character. So what precisely is an ambient space, then? As I will argue in my presentation, ambient space is a sensory effect of spatiality when a space is experienced as being particularly surrounding: a ‘space effect...

Licenciamento ambiental e sustentabilidade

Directory of Open Access Journals (Sweden)

Marcelo Macedo Valinhas

2011-12-01

Full Text Available A sustentabilidade está apoiada principalmente nas dimensões econômica, ambiental e social. No entanto, sem a dimensão política ela não se constrói. Um dos principais instrumentos de comando e controle da política nacional de meio ambiente, o licenciamento ambiental é um processo contínuo de gestão ambiental pública e privada. Analisou-se o processo de licenciamento ambiental como acoplamento estrutural entre os sistemas social, econômico e ambiental. Apesar da constatação de críticas aos mecanismos de comando e controle dos últimos anos, foi verificado que o Estado do Rio de Janeiro tem buscado integrar a política ambiental do Estado à gestão ambiental privada e que esta integração busca atender às demandas dos sistemas sociais e econômicos para as questões ambientais. Em linhas gerais, este caminho segue as estratégias e ações propostas na Agenda 21 brasileira.

[Intervention to reduce the impact of light and noise on sleep in an emergency department observation area].

Science.gov (United States)

Villamor Ordozgoiti, Alberto; Priu Parra, Inmaculada; España Salvador, María Carmen; Torres Valdés, Constancia; Bas Ciutad, María Pilar; Ponce Quílez, María Rosa

2017-02-01

To study quality of patient rest before and after an intervention to reduce nighttime light and noise in the emergency department observation area of an urban hospital. Quasi-experimental study in 2 groups before and after the intervention in the observation area of the Hospital Clínic de Barcelona. We administered a questionnaire about the quality of nighttime rest to assess the effect of light and noise on sleep. Light and noise were reduced by means of structural changes to the environment and through the introduction of protocols to modify how care plans were carried out at night. Fifty nurses participated in the pre-intervention study and 371 in the post-intervention study. Seventy-two percent and 91.37% of the patients reported resting well before and after the intervention, respectively (P< .001). Factors like pain, nursing care, or daytime naps do not affect sleep quality. Nighttime rest in emergency department observation areas is affected by ambient light and noise more than by other variables. Reducing light and noise at night can measurably improve patients' rest.

Practical Ranges of Loudness Levels of Various Types of Environmental Noise, Including Traffic Noise, Aircraft Noise, and Industrial Noise

Directory of Open Access Journals (Sweden)

Sabine A. Janssen

2011-05-01

Full Text Available In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a noise signal varies considerably with the shape of the frequency spectrum of the noise signal. In particular the bandwidth of the spectrum has a large effect on the loudness level, due to the effect of critical bands in the human hearing system. The low-frequency content of the spectrum also has an effect on the loudness level. In this note the relation between loudness level and A-weighted sound level is analyzed for various environmental noise spectra, including spectra of traffic noise, aircraft noise, and industrial noise. From loudness levels calculated for these environmental noise spectra, diagrams are constructed that show the relation between loudness level, A‑weighted sound level, and shape of the spectrum. The diagrams show that the upper limits of the loudness level for broadband environmental noise spectra are about 20 to 40 phon higher than the lower limits for narrowband spectra, which correspond to the loudness levels of pure tones. The diagrams are useful for assessing limitations and potential improvements of environmental noise control methods and policy based on A-weighted sound levels.

Saúde Ambiental: uma Análise dos Resultados das Conferências Nacionais de Meio Ambiente, Saúde e Saúde Ambiental

Directory of Open Access Journals (Sweden)

Maria Beatriz Maury de Carvalho

2010-08-01

Full Text Available A representação nas políticas públicas do conceito de saúde ambiental, como expressão do equilíbrio da rede de conexões entre a sociedade humana e a natureza é discutida neste trabalho, no intuito de demonstrar o status quo da saúde ambiental nas políticas públicas no país. Primeiro foi traçado o histórico da “ambientalização na saúde”, do conceito de saúde ambiental e da institucionalização das políticas ambientais e de saúde ambiental no âmbito dos Ministérios do Meio Ambiente e da Saúde. As interações entre as políticas de Saúde e de Meio Ambiente para a efetivação de uma Política Nacional de Saúde Ambiental e as intersecções dos resultados das Conferências Nacionais de Saúde, Meio Ambiente e Saúde Ambiental foram analisadas; concluindo- se com os avanços conseguidos pelos dois setores, os desafios para a articulação intersetorial e a participação social para a construção de políticas públicas de saúde ambiental.

EUDP project 'Low noise airfoil' - Final report

Energy Technology Data Exchange (ETDEWEB)

Bertagnolio, F. (ed.)

2012-06-15

Tunnel as the high ambient noise levels largely overwhelmed the signal of interest. Finally, a new airfoil design was proposed based on a design concept including noise reduction. The new airfoil proved to perform better aerodynamically but noise reduction were not as important as expected, mainly due to the inaccuracy of the simplified flow model used in the design algorithm. (Author)

Det ambiente

DEFF Research Database (Denmark)

Schmidt, Ulrik

Om begrebet "det ambiente", der beskriver, hvad der sker, når vi fornemmer baggrundsmusikkens diskrete beats, betragter udsigten gennem panoramavinduet eller tager 3D-brillerne på og læner os tilbage i biografsædet. Bogen analyserer, hvorfan ambiente oplevelser skabes, og hvilke konsekvenser det...

Road traffic noise: self-reported noise annoyance versus GIS modelled road traffic noise exposure.

Science.gov (United States)

Birk, Matthias; Ivina, Olga; von Klot, Stephanie; Babisch, Wolfgang; Heinrich, Joachim

2011-11-01

self-reported road traffic noise annoyance is commonly used in epidemiological studies for assessment of potential health effects. Alternatively, some studies have used geographic information system (GIS) modelled exposure to road traffic noise as an objective parameter. The aim of this study was to analyse the association between noise exposure due to neighbouring road traffic and the noise annoyance of adults, taking other determinants into consideration. parents of 951 Munich children from the two German birth cohorts GINIplus and LISAplus reported their annoyance due to road traffic noise at home. GIS modelled road traffic noise exposure (L(den), maximum within a 50 m buffer) from the noise map of the city of Munich was available for all families. GIS-based calculated distance to the closest major road (≥10,000 vehicles per day) and questionnaire based-information about family income, parental education and the type of the street of residence were explored for their potential influence. An ordered logit regression model was applied. The noise levels (L(den)) and the reported noise annoyance were compared with an established exposure-response function. the correlation between noise annoyance and noise exposure (L(den)) was fair (Spearman correlation r(s) = 0.37). The distance to a major road and the type of street were strong predictors for the noise annoyance. The annoyance modelled by the established exposure-response function and that estimated by the ordered logit model were moderately associated (Pearson's correlation r(p) = 0.50). road traffic noise annoyance was associated with GIS modelled neighbouring road traffic noise exposure (L(den)). The distance to a major road and the type of street were additional explanatory factors of the noise annoyance appraisal.

Pedagogía ambiental y didáctica ambiental como fundamentos del currículo para la formación ambiental

OpenAIRE

Julio César Tovar-Gálvez

2013-01-01

Se trata el problema de la fundamentación del currículo para la formación ambiental en la educación superior, frente a lo cual es necesario construir los conceptos de pedagogía ambiental y de didáctica ambiental. El marco teórico permite definir las categorías "lo pedagógico" y "lo didáctico", a partir de lo cual se analiza la literatura y con ello definir pedagogía ambiental y didáctica ambiental. El estado del arte permite establecer que existen dos sustentos teóricos: a) uno que se cimenta...

Judgments of aircraft noise in a traffic noise background

Science.gov (United States)

Powell, C. A.; Rice, C. G.

1975-01-01

An investigation was conducted to determine subjective response to aircraft noise in different road traffic backgrounds. In addition, two laboratory techniques for presenting the aircraft noise with the background noise were evaluated. For one technique, the background noise was continuous over an entire test session; for the other, the background noise level was changed with each aircraft noise during a session. Subjective response to aircraft noise was found to decrease with increasing background noise level, for a range of typical indoor noise levels. Subjective response was found to be highly correlated with the Noise Pollution Level (NPL) measurement scale.

Broadband ship noise and its potential impacts on Indo-Pacific humpback dolphins: Implications for conservation and management.

Science.gov (United States)

Liu, Mingming; Dong, Lijun; Lin, Mingli; Li, Songhai

2017-11-01

Ship noise pollution has raised considerable concerns among regulatory agencies and cetacean researchers worldwide. There is an urgent need to quantify ship noise in coastal areas and assess its potential biological impacts. In this study, underwater broadband noise from commercial ships in a critical habitat of Indo-Pacific humpback dolphins was recorded and analyzed. Data analysis indicated that the ship noise caused by the investigated commercial ships with an average length of 134 ± 81 m, traveling at 18.8 ± 2.5 km/h [mean ± standard deviation (SD), n = 21] comprises mid-to-high components with frequencies approaching and exceeding 100 kHz, and the ship noise could be sensed auditorily by Indo-Pacific humpback dolphins within most of their sensitive frequency range. The contributions of ship noise to ambient noise were highest in two third-octave bands with center frequencies of 8 and 50 kHz, which are within the sensitive hearing range of Indo-Pacific humpback dolphins and overlap the frequency of sounds that are biologically significant to the dolphins. It is estimated that ship noise in these third-octave bands can be auditorily sensed by and potentially affect the dolphins within 2290 ± 1172 m and 848 ± 358 m (mean ± SD, n = 21), respectively.

Types for BioAmbients

Directory of Open Access Journals (Sweden)

Sara Capecchi

2010-02-01

Full Text Available The BioAmbients calculus is a process algebra suitable for representing compartmentalization, molecular localization and movements between compartments. In this paper we enrich this calculus with a static type system classifying each ambient with group types specifying the kind of compartments in which the ambient can stay. The type system ensures that, in a well-typed process, ambients cannot be nested in a way that violates the type hierarchy. Exploiting the information given by the group types, we also extend the operational semantics of BioAmbients with rules signalling errors that may derive from undesired ambients' moves (i.e. merging incompatible tissues. Thus, the signal of errors can help the modeller to detect and locate unwanted situations that may arise in a biological system, and give practical hints on how to avoid the undesired behaviour.

Influence of Traffic Vehicles Against Ground Fundamental Frequency Prediction using Ambient Vibration Technique

Science.gov (United States)

Kamarudin, A. F.; Noh, M. S. Md; Mokhatar, S. N.; Anuar, M. A. Mohd; Ibrahim, A.; Ibrahim, Z.; Daud, M. E.

2018-04-01

Ambient vibration (AV) technique is widely used nowadays for ground fundamental frequency prediction. This technique is easy, quick, non-destructive, less operator required and reliable result. The input motions of ambient vibration are originally collected from surrounding natural and artificial excitations. But, careful data acquisition controlled must be implemented to reduce the intrusion of short period noise that could imply the quality of frequency prediction of an investigated site. In this study, investigation on the primary noise intrusion under peak (morning, afternoon and evening) and off peak (early morning) traffic flows (only 8 meter from sensor to road shoulder) against the stability and quality of ground fundamental frequency prediction were carried out. None of specific standard is available for AV data acquisition and processing. Thus, some field and processing parameters recommended by previous studies and guideline were considered. Two units of 1 Hz tri-axial seismometer sensor were closely positioned in front of the main entrance Universiti Tun Hussein Onn Malaysia. 15 minutes of recording length were taken during peak and off peak periods of traffic flows. All passing vehicles were counted and grouped into four classes. Three components of ambient vibration time series recorded in the North-South: NS, East-West: EW and vertical: UD directions were automatically computed into Horizontal to Vertical Spectral Ratio (HVSR), by using open source software of GEOPSY for fundamental ground frequency, Fo determination. Single sharp peak pattern of HVSR curves have been obtained at peak frequencies between 1.33 to 1.38 Hz which classified under soft to dense soil classification. Even identical HVSR curves pattern with close frequencies prediction were obtained under both periods of AV measurement, however the total numbers of stable and quality windows selected for HVSR computation were significantly different but both have satisfied the requirement

Theory and simulation of ion noise in microwave tubes

Science.gov (United States)

Manheimer, W. M.; Freund, H. P.; Levush, B.; Antonsen, T. M.

2001-01-01

Since there is always some ambient gas in electron beam devices, background ionization is ubiquitous. For long pulse times, the electrostatic potentials associated with this ionization can reach significant levels and give rise to such observed phenomena as phase noise in microwave tubes. This noise is usually associated with the motion of ions in the device; therefore, it is called ion noise. It often manifests itself as a slow phase fluctuation on the output signal. Observations of noise in microwave tubes such as coupled-cavity traveling wave tubes (CC-TWTs) and klystrons have been discussed in the literature. In this paper, a hybrid model is discussed in which the electron beam is described by the beam envelope equation, and the ions generated by beam ionization are treated as discrete particles using the one-dimensional equations of motion. The theoretical model provides good qualitative as well as reasonable quantitative insight into the origin of ion noise phenomena. The numerical results indicate that the model reproduces the salient features of the phase oscillations observed experimentally. That is, the scaling of the frequency of the phase oscillations with gas pressure in the device and the sensitive dependence of the phase oscillations on the focusing magnetic field. Two distinct time scales are observed in simulation. The fastest time scale oscillation is related to the bounce motion of ions in the axial potential wells formed by the scalloping of the electron beam. Slower sawtooth oscillations are observed to correlate with the well-to-well interactions induced by the ion coupling to the electron equilibrium. These oscillations are also correlated with ion dumping to the cathode or collector. As a practical matter, simulations indicate that the low frequency oscillations can be reduced significantly by using a well-matched electron beam propagating from the electron gun into the interaction circuit.

Theory and simulation of ion noise in microwave tubes

International Nuclear Information System (INIS)

Manheimer, W.M.; Freund, H.P.; Levush, B.; Antonsen, T.M. Jr.

2001-01-01

Since there is always some ambient gas in electron beam devices, background ionization is ubiquitous. For long pulse times, the electrostatic potentials associated with this ionization can reach significant levels and give rise to such observed phenomena as phase noise in microwave tubes. This noise is usually associated with the motion of ions in the device; therefore, it is called ion noise. It often manifests itself as a slow phase fluctuation on the output signal. Observations of noise in microwave tubes such as coupled-cavity traveling wave tubes (CC-TWTs) and klystrons have been discussed in the literature. In this paper, a hybrid model is discussed in which the electron beam is described by the beam envelope equation, and the ions generated by beam ionization are treated as discrete particles using the one-dimensional equations of motion. The theoretical model provides good qualitative as well as reasonable quantitative insight into the origin of ion noise phenomena. The numerical results indicate that the model reproduces the salient features of the phase oscillations observed experimentally. That is, the scaling of the frequency of the phase oscillations with gas pressure in the device and the sensitive dependence of the phase oscillations on the focusing magnetic field. Two distinct time scales are observed in simulation. The fastest time scale oscillation is related to the bounce motion of ions in the axial potential wells formed by the scalloping of the electron beam. Slower sawtooth oscillations are observed to correlate with the well-to-well interactions induced by the ion coupling to the electron equilibrium. These oscillations are also correlated with ion dumping to the cathode or collector. As a practical matter, simulations indicate that the low frequency oscillations can be reduced significantly by using a well-matched electron beam propagating from the electron gun into the interaction circuit

Acoustic noise improves motor learning in spontaneously hypertensive rats, a rat model of attention deficit hyperactivity disorder.

Science.gov (United States)

Söderlund, Göran B W; Eckernäs, Daniel; Holmblad, Olof; Bergquist, Filip

2015-03-01

The spontaneously hypertensive (SH) rat model of ADHD displays impaired motor learning. We used this characteristic to study if the recently described acoustic noise benefit in learning in children with ADHD is also observed in the SH rat model. SH rats and a Wistar control strain were trained in skilled reach and rotarod running under either ambient noise or in 75 dBA white noise. In other animals the effect of methylphenidate (MPH) on motor learning was assessed with the same paradigms. To determine if acoustic noise influenced spontaneous motor activity, the effect of acoustic noise was also determined in the open field activity paradigm. We confirm impaired motor learning in the SH rat compared to Wistar SCA controls. Acoustic noise restored motor learning in SH rats learning the Montoya reach test and the rotarod test, but had no influence on learning in Wistar rats. Noise had no effect on open field activity in SH rats, but increased corner time in Wistar. MPH completely restored rotarod learning and performance but did not improve skilled reach in the SH rat. It is suggested that the acoustic noise benefit previously reported in children with ADHD is shared by the SH rat model of ADHD, and the effect is in the same range as that of stimulant treatment. Acoustic noise may be useful as a non-pharmacological alternative to stimulant medication in the treatment of ADHD. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

A generalized formulation for noise-based seismic velocity change measurements

Science.gov (United States)

Gómez-García, C.; Brenguier, F.; Boué, P.; Shapiro, N.; Droznin, D.; Droznina, S.; Senyukov, S.; Gordeev, E.

2017-12-01

The observation of continuous seismic velocity changes is a powerful tool for detecting seasonal variations in crustal structure, volcanic unrest, co- and post-seismic evolution of stress in fault areas or the effects of fluid injection. The standard approach for measuring such velocity changes relies on comparison of travel times in the coda of a set of seismic signals, usually noise-based cross-correlations retrieved at different dates, and a reference trace, usually a averaged function over dates. A good stability in both space and time of the noise sources is then the main assumption for reliable measurements. Unfortunately, these conditions are often not fulfilled, as it happens when ambient-noise sources are non-stationary, such as the emissions of low-frequency volcanic tremors.We propose a generalized formulation for retrieving continuous time series of noise-based seismic velocity changes without any arbitrary reference cross-correlation function. We set up a general framework for future applications of this technique performing synthetic tests. In particular, we study the reliability of the retrieved velocity changes in case of seasonal-type trends, transient effects (similar to those produced as a result of an earthquake or a volcanic eruption) and sudden velocity drops and recoveries as the effects of transient local source emissions. Finally, we apply this approach to a real dataset of noise cross-correlations. We choose the Klyuchevskoy volcanic group (Kamchatka) as a case study where the recorded wavefield is hampered by loss of data and dominated by strongly localized volcanic tremor sources. Despite the mentioned wavefield contaminations, we retrieve clear seismic velocity drops associated with the eruptions of the Klyuchevskoy an the Tolbachik volcanoes in 2010 and 2012, respectively.

Exposure to air pollution and noise from road traffic and risk of congenital anomalies in the Danish National Birth Cohort

DEFF Research Database (Denmark)

Pedersen, Marie; Garne, Ester; Hansen-Nord, Nete

2017-01-01

BACKGROUND: Ambient air pollution has been associated with certain congenital anomalies, but few studies rely on assessment of fine-scale variation in air quality and associations with noise from road traffic are unexplored. METHODS: Among 84,218 liveborn singletons (1997-2002) from the Danish...... associated with these subgroups of anomalies as well as with an increased OR for orofacial cleft anomalies (1.17, 0.94-1.47). Inverse associations for several both air pollution and noise were observed for atrial septal defects (0.85, 0.68-1.04 and 0.81, 0.65-0.99, respectively). CONCLUSIONS: Residential...... road traffic exposure to noise or air pollution during pregnancy did not seem to pose a risk for development of congenital anomalies....

An Application of Reassigned Time-Frequency Representations for Seismic Noise/Signal Decomposition

Science.gov (United States)

Mousavi, S. M.; Langston, C. A.

2016-12-01

Seismic data recorded by surface arrays are often strongly contaminated by unwanted noise. This background noise makes the detection of small magnitude events difficult. An automatic method for seismic noise/signal decomposition is presented based upon an enhanced time-frequency representation. Synchrosqueezing is a time-frequency reassignment method aimed at sharpening a time-frequency picture. Noise can be distinguished from the signal and suppressed more easily in this reassigned domain. The threshold level is estimated using a general cross validation approach that does not rely on any prior knowledge about the noise level. Efficiency of thresholding has been improved by adding a pre-processing step based on higher order statistics and a post-processing step based on adaptive hard-thresholding. In doing so, both accuracy and speed of the denoising have been improved compared to our previous algorithms (Mousavi and Langston, 2016a, 2016b; Mousavi et al., 2016). The proposed algorithm can either kill the noise (either white or colored) and keep the signal or kill the signal and keep the noise. Hence, It can be used in either normal denoising applications or in ambient noise studies. Application of the proposed method on synthetic and real seismic data shows the effectiveness of the method for denoising/designaling of local microseismic, and ocean bottom seismic data. References: Mousavi, S.M., C. A. Langston., and S. P. Horton (2016), Automatic Microseismic Denoising and Onset Detection Using the Synchrosqueezed-Continuous Wavelet Transform. Geophysics. 81, V341-V355, doi: 10.1190/GEO2015-0598.1. Mousavi, S.M., and C. A. Langston (2016a), Hybrid Seismic Denoising Using Higher-Order Statistics and Improved Wavelet Block Thresholding. Bull. Seismol. Soc. Am., 106, doi: 10.1785/0120150345. Mousavi, S.M., and C.A. Langston (2016b), Adaptive noise estimation and suppression for improving microseismic event detection, Journal of Applied Geophysics., doi: http

Data based ambient lighting control

NARCIS (Netherlands)

2012-01-01

In controlling an ambient lighting element, a category of data being rendered by a host is identified, ambient lighting data associated with the identified category is retrieved, and the retrieved ambient lighting data is rendered in correspondence with the rendered data. The retrieved ambient

Biotecnologia Ambiental. Aplicacions biotecnològiques a la millora del medi ambient

OpenAIRE

Blanch i Gisbert, Anicet

2010-01-01

La biotecnología ambiental comprende el conjunto de actividades tecnológicas que facilitan la comprensión y la gestión de los sistemas biológicos en el medio ambiente, con el fin de proveer productos y servicios. Actualmente, la gestión del medio ambiente y de sus recursos naturales no se comprende si no se realiza de manera sostenible. Los avances científicos y tecnológicos le están permitiendo a la biotecnología ambiental, el desarrollo de nuevas herramientas y aplicaciones con los que resp...

The future is 'ambient'

Science.gov (United States)

Lugmayr, Artur

2006-02-01

The research field of ambient media starts to spread rapidly and first applications for consumer homes are on the way. Ambient media is the logical continuation of research around media. Media has been evolving from old media (e.g. print media), to integrated presentation in one form (multimedia - or new media), to generating a synthetic world (virtual reality), to the natural environment is the user-interface (ambient media), and will be evolving towards real/synthetic undistinguishable media (bio-media or bio-multimedia). After the IT bubble was bursting, multimedia was lacking a vision of potential future scenarios and applications. Within this research paper the potentials, applications, and market available solutions of mobile ambient multimedia are studied. The different features of ambient mobile multimedia are manifold and include wearable computers, adaptive software, context awareness, ubiquitous computers, middleware, and wireless networks. The paper especially focuses on algorithms and methods that can be utilized to realize modern mobile ambient systems.

Bedload transport from spectral analysis of seismic noise near rivers

Science.gov (United States)

Hsu, L.; Finnegan, N. J.; Brodsky, E. E.

2010-12-01

Channel change in rivers is driven by bedload sediment transport. However, the nonlinear nature of sediment transport combined with the difficulty of making direct observations in rivers at flood hinder prediction of the timing and magnitude of bedload movement. Recent studies have shown that spectral analysis of seismic noise from seismometers near rivers illustrate a correlation between the relative amplitude of high frequency (>1 Hz) seismic noise and conditions for bedload transport, presumably from the energy transferred from clast collisions with the channel. However, a previous study in the Himalayas did not contain extensive bedload transport or discharge measurements, and the correspondence of seismic noise with proxy variables such as regional hydrologic and meteorologic data was not exact. A more complete understanding of the relationship between bedload transport and seismic noise would be valuable for extending the spatial and temporal extent of bedload data. To explore the direct relationship between bedload transport and seismic noise, we examine data from several seismic stations near the Trinity River in California, where the fluvial morphodynamics and bedload rating curves have been studied extensively. We compare the relative amplitude of the ambient seismic noise with records of water discharge and sediment transport. We also examine the noise at hourly, daily, and seasonal timescales to determine other possible sources of noise. We report the influence of variables such as local river slope, adjacent geology, anthropogenic noise, and distance from the river. The results illustrate the feasibility of using existing seismic arrays to sense radiated energy from processes of bedload transport. In addition, the results can be used to design future seismic array campaigns to optimize information about bedload transport. This technique provides great spatial and temporal coverage, and can be performed where direct bedload measurements are difficult or

Towards New Ambient Light Systems: a Close Look at Existing Encodings of Ambient Light Systems

Directory of Open Access Journals (Sweden)

Andrii Matviienko

2015-10-01

Full Text Available Ambient systems provide information in the periphery of a user’s attention. Their aim is to present information as unobtrusively as possible to avoid interrupting primary tasks (e.g. writing or reading. In recent years, light has been used to create ambient systems to display information. Examples of ambient light systems range from simple notification systems such as displaying messages or calendar event reminders, to more complex systems such as focusing on conveying information regarding health activity tracking. However, for ambient light systems, there is a broad design space that lacks guidelines on when to make use of light displays and how to design them. In this paper we provide a systematic overview of existing ambient light systems over four identified information classes derived from 72 existing ambient light systems. The most prominent encoding parameters among the surveyed ambient light systems are color, brightness, and their combination. By analyzing existing ambient light systems, we provide a first step towards developing guidelines for designing future ambient light systems.

Direct-reading dial for noise temperature and noise resistance

DEFF Research Database (Denmark)

Diamond, J.M.

1967-01-01

An attenuator arrangement for a noise generator is described. The scheme permits direct reading of both noise resistance and noise temperature¿the latter with a choice of source resistance.......An attenuator arrangement for a noise generator is described. The scheme permits direct reading of both noise resistance and noise temperature¿the latter with a choice of source resistance....

Noise frame duration, masking potency and whiteness of temporal noise.

Science.gov (United States)

Kukkonen, Heljä; Rovamo, Jyrki; Donner, Kristian; Tammikallio, Marja; Raninen, Antti

2002-09-01

Because of the limited contrast range, increasing the duration of the noise frame is often the only option for increasing the masking potency of external, white temporal noise. This, however, reduces the high-frequency cutoff beyond which noise is no longer white. This study was conducted to determine the longest noise frame duration that produces the strongest masking effect and still mimics white noise on the detection of sinusoidal flicker. Contrast energy thresholds (E(th)) were measured for flicker at 1.25 to 20 Hz in strong, purely temporal (spatially uniform), additive, external noise. The masking power of white external noise, characterized by its spectral density at zero frequency N0, increases with the duration of the noise frame. For short noise frame durations, E(th) increased in direct proportion to N0, keeping the nominal signal-to-noise ratio [SNR = (E(th)/N0)(0.5)] constant at threshold. The masking effect thus increased with the duration of the noise frame and the noise mimicked white noise. When noise frame duration and N0 increased further, the nominal SNR at threshold started to decrease, indicating that noise no longer mimicked white noise. The minimum number of noise frames per flicker cycle needed to mimic white noise decreased with increasing flicker frequency from 8.3 at 1.25 Hz to 1.6 at 20 Hz. The critical high-frequency cutoff of detection-limiting temporal noise in terms of noise frames per signal cycle depends on the temporal frequency of the signal. This is opposite to the situation in the spatial domain and must be taken into consideration when temporal signals are masked with temporal noise.

Direct Signal-to-Noise Quality Comparison between an Electronic and Conventional Stethoscope aboard the International Space Station

Science.gov (United States)

Marshburn, Thomas; Cole, Richard; Ebert, Doug; Bauer, Pete

2014-01-01

Introduction: Evaluation of heart, lung, and bowel sounds is routinely performed with the use of a stethoscope to help detect a broad range of medical conditions. Stethoscope acquired information is even more valuable in a resource limited environments such as the International Space Station (ISS) where additional testing is not available. The high ambient noise level aboard the ISS poses a specific challenge to auscultation by stethoscope. An electronic stethoscope's ambient noise-reduction, greater sound amplification, recording capabilities, and sound visualization software may be an advantage to a conventional stethoscope in this environment. Methods: A single operator rated signal-to-noise quality from a conventional stethoscope (Littman 2218BE) and an electronic stethoscope (Litmann 3200). Borborygmi, pulmonic, and cardiac sound quality was ranked with both stethoscopes. Signal-to-noise rankings were preformed on a 1 to 10 subjective scale with 1 being inaudible, 6 the expected quality in an emergency department, 8 the expected quality in a clinic, and 10 the clearest possible quality. Testing took place in the Japanese Pressurized Module (JPM), Unity (Node 2), Destiny (US Lab), Tranquility (Node 3), and the Cupola of the International Space Station. All examinations were conducted at a single point in time. Results: The electronic stethoscope's performance ranked higher than the conventional stethoscope for each body sound in all modules tested. The electronic stethoscope's sound quality was rated between 7 and 10 in all modules tested. In comparison, the traditional stethoscope's sound quality was rated between 4 and 7. The signal to noise ratio of borborygmi showed the biggest difference between stethoscopes. In the modules tested, the auscultation of borborygmi was rated between 5 and 7 by the conventional stethoscope and consistently 10 by the electronic stethoscope. Discussion: This stethoscope comparison was limited to a single operator. However, we

Active noise control in a duct to cancel broadband noise

Science.gov (United States)

Chen, Kuan-Chun; Chang, Cheng-Yuan; Kuo, Sen M.

2017-09-01

The paper presents cancelling duct noises by using the active noise control (ANC) techniques. We use the single channel feed forward algorithm with feedback neutralization to realize ANC. Several kinds of ducts noises including tonal noises, sweep tonal signals, and white noise had investigated. Experimental results show that the proposed ANC system can cancel these noises in a PVC duct very well. The noise reduction of white noise can be up to 20 dB.

Ambient Dried Aerogels

Science.gov (United States)

Jones, Steven M.; Paik, Jong-Ah

2013-01-01

A method has been developed for creating aerogel using normal pressure and ambient temperatures. All spacecraft, satellites, and landers require the use of thermal insulation due to the extreme environments encountered in space and on extraterrestrial bodies. Ambient dried aerogels introduce the possibility of using aerogel as thermal insulation in a wide variety of instances where supercritically dried aerogels cannot be used. More specifically, thermoelectric devices can use ambient dried aerogel, where the advantages are in situ production using the cast-in ability of an aerogel. Previously, aerogels required supercritical conditions (high temperature and high pressure) to be dried. Ambient dried aerogels can be dried at room temperature and pressure. This allows many materials, such as plastics and certain metal alloys that cannot survive supercritical conditions, to be directly immersed in liquid aerogel precursor and then encapsulated in the final, dried aerogel. Additionally, the metalized Mylar films that could not survive the previous methods of making aerogels can survive the ambient drying technique, thus making multilayer insulation (MLI) materials possible. This results in lighter insulation material as well. Because this innovation does not require high-temperature or high-pressure drying, ambient dried aerogels are much less expensive to produce. The equipment needed to conduct supercritical drying costs many tens of thousands of dollars, and has associated running expenses for power, pressurized gasses, and maintenance. The ambient drying process also expands the size of the pieces of aerogel that can be made because a high-temperature, high-pressure system typically has internal dimensions of up to 30 cm in diameter and 60 cm in height. In the case of this innovation, the only limitation on the size of the aerogels produced would be in the ability of the solvent in the wet gel to escape from the gel network.

Underwater noise from three types of offshore wind turbines: estimation of impact zones for harbor porpoises and harbor seals.

Science.gov (United States)

Tougaard, Jakob; Henriksen, Oluf Damsgaard; Miller, Lee A

2009-06-01

Underwater noise was recorded from three different types of wind turbines in Denmark and Sweden (Middelgrunden, Vindeby, and Bockstigen-Valar) during normal operation. Wind turbine noise was only measurable above ambient noise at frequencies below 500 Hz. Total sound pressure level was in the range 109-127 dB re 1 microPa rms, measured at distances between 14 and 20 m from the foundations. The 1/3-octave noise levels were compared with audiograms of harbor seals and harbor porpoises. Maximum 1/3-octave levels were in the range 106-126 dB re 1 microPa rms. Maximum range of audibility was estimated under two extreme assumptions on transmission loss (3 and 9 dB per doubling of distance, respectively). Audibility was low for harbor porpoises extending 20-70 m from the foundation, whereas audibility for harbor seals ranged from less than 100 m to several kilometers. Behavioral reactions of porpoises to the noise appear unlikely except if they are very close to the foundations. However, behavioral reactions from seals cannot be excluded up to distances of a few hundred meters. It is unlikely that the noise reaches dangerous levels at any distance from the turbines and the noise is considered incapable of masking acoustic communication by seals and porpoises.

CONDITION ASSESSMENT OF SUBJECTIVE COMFORT AND THE REACTIONS OF THE POPULATION IN THE URBAN CONTEXT OF EXPOSURE TO NOISE

Directory of Open Access Journals (Sweden)

NICA-BADEA Delia

2012-05-01

Full Text Available The paper considers this issue matters as of interference noise of the ordinary activity of the population owing to its cause and its presence in all departments of life. Noise pollution is a major problem in all countries where we are witnessing a phenomenon of magnification levels of noise having effects more or less aggressive about comfort and even health. Are presented arguments relating to the characterization of noise as a risk factor in the induction of pathologies such as: auditory disorders, hypertension, ischemic heart disease aggravation, discomfort, sleep disorders and decreasing school performance in children. For the evaluation and management of ambient noise has developed a study aimed at assessing the state of comfort and subjective reactions of residents in order to fundamentarii measures for reducing the levels of exposure and prevention of the effects of population exposed to noise in the street. In areas with heavy traffic confirm the existence of risk perception of 56% of the people who accuse the discomfort caused by noise in homes during the day and during the night rate is 40%. The age groups most affected are 51-65 years and over 65 years old, because they spend most of the time period in the home.

Crustal structure and Seismic Hazard studies in Nigeria from ambient noise and earthquakes

Science.gov (United States)

Kadiri, U. A.

2016-12-01

The crust, upper Mantle and seismic hazard studies have been carried out in Nigeria using noise and earthquake data. The data were acquired from stations in Nigeria and international Agencies. Firstly, known depths of sediments in the Lower Benue Trough (LBT) were collected from wells; Resonance frequency (Fo) and average shear-wave velocities (Vs) were then computed using Matlab. Secondly, average velocities were estimated from noise cross-correlation along seismic stations. Thirdly, the moho depths beneath Ife, Kaduna and Nsukka stations were estimated, as well as Vp/Vs ratio using 2009 earthquake with epicenter in Nigeria. Finally, Statistical and Probabilistic Seismic Hazard Assessment (PSHA) were used to compute seismic hazard parameters in Nigeria and its surroundings. The results showed that, soils on the LBT with average shear wave velocity of about 5684m/s would experience more amplification in case of an earthquake, compared to the basement complex in Nigeria. The Vs beneath the seismic stations in Nigeria were also estimated as 288m/s, 1019m/s, 940.6m/s and 255.02m/s in Ife, Nsukka, Awka, and Abakaliki respectively. The average velocity along the station paths was 4.5km/secs, and the Vp, Vs for depths 100-500km profile in parts of South West Nigeria increased from about 5.83-6.42Km/sec and 3.48-6.31km/s respectively with Vp/Vs ratio decreasing from 1.68 to 1.02. Statistical analysis revealed a trend of increasing earthquake occurrence along the Mid-Atlantic Ridge and tending to West African region. The analysis of PSHA shows the likelihood of earthquakes with different magnitudes occurring in Nigeria and other parts West Africa in future. This work is aimed at addressing critical issues regarding sites effect characterization, improved earthquake location and robust seismic hazards assessment for planning in the choice of sites for critical facilities in Nigeria. Keywords: Sediment thickness, Resonance Frequency, Average Velocity, Seismic Hazard, Nigeria

Detection of very long period solar free oscillations in ambient seismic array noise

Science.gov (United States)

Caton, R.; Pavlis, G. L.; Thomson, D. J.; Vernon, F.

2017-12-01

For nearly two decades long-period seismologists have been aware that the Earth's free oscillations are in a constant state of excitement, even in the absence of large earthquakes. This phenomenon is now called the "Earth's hum," and much research has been done to determine what generates this hum. Here we examine a hypothesis first put forward by Thomson et al. in 2007 that a portion of the hum's energy comes from the sun. They hypothesized that solar free oscillations couple into the solid Earth, likely through electromagnetic processes, and produce signals that are observable in the frequency domain. If this is true, then at least some measurement of helioseismic oscillations may be possible using relatively cheap, ground-based instruments rather than spacecraft. In this project we attempt to improve upon previous studies by producing spectra from seismic arrays, rather than a single station. We use data from two arrays: The Homestake Mine 3D array in Lead, SD, and the Pinyon Flats array, which has seismometers in boreholes drilled into bedrock. Both have exceptionally low noise levels at ultra long periods and show easily visible earth tides on horizontal component data filtered to below the microseism band. In the Homestake data, below 500 μHz we have found evidence of what we suggest may be closely spaced solar g-mode lines. Such modes are produced by a density inversion at the top of the solar core. There is no sign of these modes in the Pinyon Flats data, but we find this is likely due to the signal-to-noise ratio of those data, which is significantly lower than Homestake. Significance tests of bands below 500 μHz indicate with probability levels as high as 40σ that these lines are not the result of random processes. Critical examination of our processing steps for sources of bias indicate that the observed line structure is not a processing artifact.

Long-period noise source inversion in a 3-D heterogeneous Earth

Science.gov (United States)

Sager, K.; Ermert, L. A.; Afanasiev, M.; Boehm, C.; Fichtner, A.

2017-12-01

We have implemented a new method for ambient noise source inversion that fully honors finite-frequency wave propagation and 3-D heterogeneous Earth structure.Here, we present results of its first application to the Earth's long-period background signal, the hum, in a period band of around 120 - 300 s. In addition to being a computationally convenient test case, the hum is also the topic of ongoing research in its own right, because different physical mechanisms have been proposed for its excitation. The broad patterns of this model for South and North hemisphere winter are qualitatively consistent with previous long-term studies of the hum sources; however, thanks to methodological improvements, the iterative refinement, and the use of a comparatively extensive dataset, we retrieve a more detailed model in certain locations. In particular, our results support findings that the dominant hum sources are focused along coasts and shelf areas, particularly in the North hemisphere winter, with a possible though not well-constrained contribution of pelagic sources. Additionally, our findings indicate that hum source locations in the ocean, tentatively linked to locally high bathymetry, are important contributors particularly during South hemisphere winter. These results, in conjunction with synthetic recovery tests and observed cross-correlation waveforms, suggest that hum sources are rather narrowly concentrated in space, with length scales on the order of few hundred kilometers. Future work includes the extension of the model to spring and fall season and to shorter periods, as well as its use in full-waveform ambient noise inversion for 3-D Earth structure.

CUIDADO AMBIENTAL E RESPONSABILIDADE: POSSÍVEL DIÁLOGO ENTRE PSICOLOGIA AMBIENTAL E LOGOTERAPIA

Directory of Open Access Journals (Sweden)

Diogo Arnaldo Corrêa

2016-05-01

Full Text Available O cuidado ambiental vem sendo marcado pela tônica da conservação e da promoção da sustentabilidade. A premente necessidade de um dado compromisso e educação ambiental e de condutas pró-ambientais vem sendo defendida em vários contextos: na mídia, nas políticas públicas, por meio de campanhas sazonais. Todavia, pouco se descreve acerca do sentido presente nos modos de cuidado configurados a partir da inter-relação pessoa-ambiente. Nesta perspectiva, este estudo objetivou promover um possível diálogo a partir das contribuições da Psicologia Ambiental e da Logoterapia visando aproximar a noção de cuidado ambiental, delineada pela Psicologia Ambiental, à ideia de responsabilidade, como defendida pela Logoterapia, por meio de uma revisão bibliográfica. As articulações propositadas corroboraram, portanto, para acenar que a relação pessoa-ambiente pode ser arraigada em qualidade se a responsabilidade é reconhecida em sua propriedade de potencial humano, o que pode favorecer na emergência do sentido das atitudes e condutas pró-ambientais e explicitar o caráter de tarefa única e irrepetível inerente à vida.

Distribution of flux-pinning energies in YBa2Cu3O(7-delta) and Bi2Sr2CaCu2O(8+delta) from flux noise

Science.gov (United States)

Ferrari, M. J.; Johnson, Mark; Wellstood, Frederick C.; Clarke, John; Mitzi, D.

1990-01-01

The spectral density of the magnetic flux noise measured in high-temperature superconductors in low magnetic fields scales approximately as the inverse of the frequency and increases with temperature. The temperature and frequency dependence of the noise are used to determine the pinning energies of individual flux vortices in thermal equilibrium. The distribution of pinning energies below 0.1 eV in YBa(2)Cu(3)O(7-delta) and near 0.2 eV in Bi(2)Sr(2)CaCu(2)O(8+delta). The noise power is proportional to the ambient magnetic field, indicating that the vortex motion is uncorrelated.

Sounds and Noises. A Position Paper on Noise Pollution.

Science.gov (United States)

Chapman, Thomas L.

This position paper focuses on noise pollution and the problems and solutions associated with this form of pollution. The paper is divided into the following five sections: Noise and the Ear, Noise Measurement, III Effects of Noise, Acoustics and Action, and Programs and Activities. The first section identifies noise and sound, the beginnings of…

Vessel noise cuts down communication space for vocalizing fish and marine mammals.

Science.gov (United States)

Putland, Rosalyn L; Merchant, Nathan D; Farcas, Adrian; Radford, Craig A

2018-04-01

Anthropogenic noise across the world's oceans threatens the ability of vocalizing marine species to communicate. Some species vocalize at key life stages or whilst foraging, and disruption to the acoustic habitat at these times could lead to adverse consequences at the population level. To investigate the risk of these impacts, we investigated the effect of vessel noise on the communication space of the Bryde's whale Balaenoptera edeni, an endangered species which vocalizes at low frequencies, and bigeye Pempheris adspersa, a nocturnal fish species which uses contact calls to maintain group cohesion while foraging. By combining long-term acoustic monitoring data with AIS vessel-tracking data and acoustic propagation modelling, the impact of vessel noise on their communication space was determined. Routine vessel passages cut down communication space by up to 61.5% for bigeyes and 87.4% for Bryde's whales. This influence of vessel noise on communication space exceeded natural variability for between 3.9 and 18.9% of the monitoring period. Additionally, during the closest point of approach of a large commercial vessel, communication space of both species was reduced by a maximum of 99% compared to the ambient soundscape. These results suggest that vessel noise reduces communication space beyond the evolutionary context of these species and may have chronic effects on these populations. To combat this risk, we propose the application or extension of ship speed restrictions in ecologically significant areas, since our results indicate a reduction in sound source levels for vessels transiting at lower speeds. © 2017 John Wiley & Sons Ltd.

Passive monitoring of a sea dike during a tidal cycle using sea waves as a seismic noise source

Science.gov (United States)

Joubert, Anaëlle; Feuvre, Mathieu Le; Cote, Philippe

2018-05-01

Over the past decade, ambient seismic noise has been used successfully to monitor various geological objects with high accuracy. Recently, it has been shown that surface seismic waves propagating within a sea dike body can be retrieved from the cross-correlation of ambient seismic noise generated by sea waves. We use sea wave impacts to monitor the response of a sea dike during a tidal cycle using empirical Green's functions. These are obtained either by cross-correlation or deconvolution, from signals recorded by sensors installed linearly on the crest of a dike. Our analysis is based on delay and spectral amplitude measurements performed on reconstructed surface waves propagating along the array. We show that localized variations of velocity and attenuation are correlated with changes in water level as a probable consequence of water infiltration inside the structure. Sea dike monitoring is of critical importance for safety and economic reasons, as internal erosion is generally only detected at late stages by visual observations. The method proposed here may provide a solution for detecting structural weaknesses, monitoring progressive internal erosion, and delineating areas of interest for further geotechnical studies, in view to understanding the erosion mechanisms involved.

Noise-induced hearing loss: a recreational noise perspective.

Science.gov (United States)

Ivory, Robert; Kane, Rebecca; Diaz, Rodney C

2014-10-01

This review will discuss the real-world risk factors involved in noise-induced hearing loss as a result of common and popular recreational activities prone to mid and high levels of noise exposure. Although there are currently no interventional measures available to reverse or mitigate preexisting hearing loss from noise, we discuss the vital importance of hearing loss prevention from noise exposure avoidance and reduction. Despite a seeming understanding of the effects of noise exposure from various recreational activities and devices, a large percentage of the general public who is at risk of such noise-induced hearing loss still chooses to refrain from using hearing protection instruments. While occupational exposures pose the greatest traditional risk to hearing conservation in selected workers, recreational risk factors for noise-induced hearing loss may be more insidious in overall effect given the indifferent attitude of much of the general public and particularly our youths toward hearing protection during recreational activities. Active counseling regarding the consequences of excessive noise exposure and the potential benefits to hearing from usage of hearing protection instruments is critical to providing best possible care in the hearing health professions.

Ambient vibrations of unstable rock slopes - insights from numerical modeling

Science.gov (United States)

Burjanek, Jan; Kleinbrod, Ulrike; Fäh, Donat

2017-04-01

The recent events in Nepal (2015 M7.8 Gorkha) and New Zealand (2016 M7.8 Kaikoura) highlighted the importance of earthquake-induced landslides, which caused significant damages. Moreover, landslide created dams present a potential developing hazard. In order to reduce the costly consequences of such events it is important to detect and characterize earthquake susceptible rock slope instabilities before an event, and to take mitigation measures. For the characterisation of instable slopes, acquisition of ambient vibrations might be a new alternative to the already existing methods. We present both observations and 3D numerical simulations of the ambient vibrations of unstable slopes. In particular, models of representative real sites have been developed based on detailed terrain mapping and used for the comparison between synthetics and observations. A finite-difference code has been adopted for the seismic wave propagation in a 3D inhomogeneous visco-elastic media with irregular free surface. It utilizes a curvilinear grid for a precise modeling of curved topography and local mesh refinement to make computational mesh finer near the free surface. Topographic site effects, controlled merely by the shape of the topography, do not explain the observed seismic response. In contrast, steeply-dipping compliant fractures have been found to play a key role in fitting observations. Notably, the synthetized response is controlled by inertial mass of the unstable rock, and by stiffness, depth and network density of the fractures. The developed models fit observed extreme amplification levels (factors of 70!) and show directionality as well. This represents a possibility to characterize slope structure and infer depth or volume of the slope instability from the ambient noise recordings in the future.

GSpecDisp: A matlab GUI package for phase-velocity dispersion measurements from ambient-noise correlations

Science.gov (United States)

Sadeghisorkhani, Hamzeh; Gudmundsson, Ólafur; Tryggvason, Ari

2018-01-01

We present a graphical user interface (GUI) package to facilitate phase-velocity dispersion measurements of surface waves in noise-correlation traces. The package, called GSpecDisp, provides an interactive environment for the measurements and presentation of the results. The selection of a dispersion curve can be done automatically or manually within the package. The data are time-domain cross-correlations in SAC format, but GSpecDisp measures phase velocity in the spectral domain. Two types of phase-velocity dispersion measurements can be carried out with GSpecDisp; (1) average velocity of a region, and (2) single-pair phase velocity. Both measurements are done by matching the real part of the cross-correlation spectrum with the appropriate Bessel function. Advantages of these two types of measurements are that no prior knowledge about surface-wave dispersion in the region is needed, and that phase velocity can be measured up to that period for which the inter-station distance corresponds to one wavelength. GSpecDisp can measure the phase velocity of Rayleigh and Love waves from all possible components of the noise correlation tensor. First, we briefly present the theory behind the methods that are used, and then describe different modules of the package. Finally, we validate the developed algorithms by applying them to synthetic and real data, and by comparison with other methods. The source code of GSpecDisp can be downloaded from: https://github.com/Hamzeh-Sadeghi/GSpecDisp

Practical ranges of loudness levels of various types of environmental noise, including traffic noise, aircraft noise, and industrial noise

NARCIS (Netherlands)

Salomons, E.M.; Janssen, S.A.

2011-01-01

In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a

Preceding weak noise sharpens the frequency tuning and elevates the response threshold of the mouse inferior collicular neurons through GABAergic inhibition.

Science.gov (United States)

Wang, Xin; Jen, Philip H-S; Wu, Fei-Jian; Chen, Qi-Cai

2007-09-05

In acoustic communication, animals must extract biologically relevant signals that are embedded in noisy environment. The present study examines how weak noise may affect the auditory sensitivity of neurons in the central nucleus of the mouse inferior colliculus (IC) which receives convergent excitatory and inhibitory inputs from both lower and higher auditory centers. Specifically, we studied the frequency sensitivity and minimum threshold of IC neurons using a pure tone probe and a weak white noise masker under forward masking paradigm. For most IC neurons, probe-elicited response was decreased by a weak white noise that was presented at a specific gap (i.e. time window). When presented within this time window, weak noise masking sharpened the frequency tuning curve and increased the minimum threshold of IC neurons. The degree of weak noise masking of these two measurements increased with noise duration. Sharpening of the frequency tuning curve and increasing of the minimum threshold of IC neurons during weak noise masking were mostly mediated through GABAergic inhibition. In addition, sharpening of frequency tuning curve by the weak noise masker was more effective at the high than at low frequency limb. These data indicate that in the real world the ambient noise may improve frequency sensitivity of IC neurons through GABAergic inhibition while inevitably decrease the frequency response range and sensitivity of IC neurons.

Effects of a traffic noise background on judgements of aircraft noise

Science.gov (United States)

Powell, C. A.; Rice, C. G.

1974-01-01

A study was conducted in which subjects judged aircraft noises in the presence of road traffic background noise. Two different techniques for presenting the background noises were evaluated. For one technique, the background noise was continuous over the whole of a test session. For the other, the background noise was changed with each aircraft noise. A range of aircraft noise levels and traffic noise levels were presented to simulate typical indoor levels.

Evaluation of noise pollution in oil extracting region of Lavan and the effect of noise enclosure on noise abatement

Directory of Open Access Journals (Sweden)

F. Golbabaei

2007-09-01

Full Text Available Background and aims   Overexposure to industrial noise pollution induce hearing loss workers. Occupational hearing loss may cause interference whit oral communication, so it may  increase the risk of occupational accidents in workplace as well as affects whit social activities.  This study was conducted on Lavan Island, are of oil extracting regions in the south of Iran. The  object of this study was to evaluate noise pollution and determining the effect of noise enclosure  on noise abatement.   Methods   The noise sources were recognized and noise pressure level was measured by CEL- 440. Noise dose of the exposed workers in high level noise area were measured by CEL 272.   Results   Major noise sources were gas turbines, diesel generators, compressors, fans and gas containing pips, noise contour map revealers that noise level were higher than the recommended national exposure limit. The results of workers noise dose show that their noise exposure were  higher than the recommended value, (p<0.001. Finally, by using the results of noise frequency  analysis of different noise sources, the noise pressure level of each sources was determined in   terms of enclosing them.   Conclusion   By enclosing the noise sources, noise pressure levels can be lowered douse to  acceptable levels but limitation of applying enclosure should be regarded.  

Noise cancellation properties of displacement noise free interferometer

International Nuclear Information System (INIS)

Sato, Shuichi; Kawamura, Seiji; Nishizawa, Atsushi; Chen Yanbei

2010-01-01

We have demonstrated the practical feasibility of a displacement- and frequency-noise-free laser interferometer (DFI) by partially implementing a recently proposed optical configuration using bi-directional Mach-Zehnder interferometers (MZIs). The noise cancellation efficiency was evaluated by comparing the displacement noise spectrum of the MZIs and the DFI, demonstrating up to 50 dB of noise cancellation. In addition, the possible extension of DFI as QND device is explored.

Retrieving robust noise-based seismic velocity changes from sparse data sets: synthetic tests and application to Klyuchevskoy volcanic group (Kamchatka)

Science.gov (United States)

Gómez-García, C.; Brenguier, F.; Boué, P.; Shapiro, N. M.; Droznin, D. V.; Droznina, S. Ya; Senyukov, S. L.; Gordeev, E. I.

2018-05-01

Continuous noise-based monitoring of seismic velocity changes provides insights into volcanic unrest, earthquake mechanisms and fluid injection in the sub-surface. The standard monitoring approach relies on measuring travel time changes of late coda arrivals between daily and reference noise cross-correlations, usually chosen as stacks of daily cross-correlations. The main assumption of this method is that the shape of the noise correlations does not change over time or, in other terms, that the ambient-noise sources are stationary through time. These conditions are not fulfilled when a strong episodic source of noise, such as a volcanic tremor for example, perturbs the reconstructed Green's function. In this paper we propose a general formulation for retrieving continuous time series of noise-based seismic velocity changes without the requirement of any arbitrary reference cross-correlation function. Instead, we measure the changes between all possible pairs of daily cross-correlations and invert them using different smoothing parameters to obtain the final velocity change curve. We perform synthetic tests in order to establish a general framework for future applications of this technique. In particular, we study the reliability of velocity change measurements versus the stability of noise cross-correlation functions. We apply this approach to a complex dataset of noise cross-correlations at Klyuchevskoy volcanic group (Kamchatka), hampered by loss of data and the presence of highly non-stationary seismic tremors.

Pedagogía ambiental y didáctica ambiental: tendencias en la educación superior

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Julio César Tovar-Gálvez

2017-01-01

Full Text Available El artículo aborda el problema del currículo de educación ambiental en la educación superior, para lo que se centra en los conceptos pedagogía ambiental y didáctica ambiental. La metodología consiste en realizar un estado del arte para identificar las tendencias existentes sobre pedagogía ambiental y didáctica ambiental, para desde allí diseñar una encuesta que es dirigida a profesores y estudiantes de programas con formación en lo ambiental, de algunas universidades en Bogotá, con el objetivo de identificar sus opiniones como expertos en lo ambiental. Los resultados muestran un especial énfasis en las tendencias sobre la complejidad, pero así mismo plantean la posibilidad de múltiples modelos según los contextos y necesidades.

Masking potency and whiteness of noise at various noise check sizes.

Science.gov (United States)

Kukkonen, H; Rovamo, J; Näsänen, R

1995-02-01

The masking effect of spatial noise can be increased by increasing either the rms contrast or check size of noise. In this study, the authors investigated the largest noise check size that still mimics the effect of white noise in grating detection and how it depends on the bandwidth and spatial frequency of a grating. The authors measured contrast energy thresholds, E, for vertical cosine gratings at various spatial frequencies and bandwidths. Gratings were embedded in two-dimensional spatial noise. The side length of the square noise checks was varied in the experiments. The spectral density, N(0,0), of white spatial noise at zero frequency was calculated by multiplying the noise check area by the rms contrast of noise squared. The physical signal-to-noise ratio at threshold [E/N(0,0)]0.5 was initially constant but then started to decrease. The largest noise check that still produced a constant physical signal-to-noise ratio at threshold was directly proportional to the spatial frequency. When expressed as a fraction of grating cycle, the largest noise check size depended only on stimulus bandwidth. The smallest number of noise checks per grating cycle needed to mimic the effect of white noise decreased from 4.2 to 2.6 when the number of grating cycles increased from 1 to 64. Spatial noise can be regarded as white in grating detection if there are at least four square noise checks per grating cycle at all spatial frequencies.

POLÍTICA PÚBLICA AMBIENTAL Y AMBIENTE EN EL VALLE DEL CAUCA, 1991-2010

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Álvaro Quiceno Martínez

2010-01-01

Full Text Available La política pública ambiental en el Valle del Cauca, a partir de 1991, va en contravía de la conservación ambiental al enfatizar en el crecimiento económico, la generación de plusvalía y la ampliación de la tasa de ganancia. Para la realización de esta investigación se adoptó como herramienta metodológica la revisión bibliográfica. Se halló que la política pública ambiental en el Valle se ha orientado a subsidiar monetaria, ecológica, ambiental y socialmente al sector cañicultor. Se concluye que dicha política ha contribuido al desequilibrio ecológico y al deterioro ambiental.

Ambiente e justiça: sobre a utilidade do conceito de racismo ambiental no contexto brasileiro

OpenAIRE

Silva, Lays Helena Paes e

2013-01-01

A ideia de crise ambiental suscita discussões a respeito de distintas concepções de natureza e de ambiente e das disputas simbólicas e materiais neste meio. Uma concepção que toma sociedade e ambiente como pares inseparáveis levou à emergência, nos Estados Unidos, de movimentos que introduziram conceitos como justiça ambiental e racismo ambiental. No Brasil, surgiram movimentos e estudos focados nas mesmas bandeiras de luta e nos mesmos conceitos. Considerando as especificidades do racismo no...

Performance of FHWA model for predicting traffic noise: a case study of metropolitan city, Lucknow (India

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J. B. Srivastava

2009-09-01

Full Text Available Industrial and transport activities are the two major sources of noise pollution in any metropolitan city. Lucknow city, the capital of the largest populated state Uttar Pradesh in India has an area of 310 sq. km and is rapidly growing as a commercial, industrial and trading centre of northern India. The population of Lucknow city as per census 2001 is 22.45 Lacs. It is expected that by the year 2021 it will make 45 Lacs. The total vehicle population in Lucknow city on 31 March 2008, was nearly 1 million with almost 80% two wheelers, 12% cars, 1.36% three wheelers, 0.45% buses etc. A study was carried out to assess the existing status of noise levels and its impacts on the environment with a possibility of further expansion of the city. Ambient noise levels were measured at different locations selected on the basis of land use such as silence, heavy traffic and residential and commercial zones. It was found that noise levels at all selected locations were much higher (75–90 dB than the prescribed limits. The observed traffic volume and data on road geometry were used to predict noise levels using Federal Highway Administration Agency (FHWA model and the calculated noise levels were compared with the observed levels for checking the suitability of this model for predicting the future levels. It was established that the results obtained by FHWA model were very close to the observed noise levels and that the model was suitable to be used for other similar metropolitan cities in India.

Non-Markovian noise

International Nuclear Information System (INIS)

Fulinski, A.

1994-01-01

The properties of non-Markovian noises with exponentially correlated memory are discussed. Considered are dichotomic noise, white shot noise, Gaussian white noise, and Gaussian colored noise. The stationary correlation functions of the non-Markovian versions of these noises are given by linear combinations of two or three exponential functions (colored noises) or of the δ function and exponential function (white noises). The non-Markovian white noises are well defined only when the kernel of the non-Markovian master equation contains a nonzero admixture of a Markovian term. Approximate equations governing the probability densities for processes driven by such non-Markovian noises are derived, including non-Markovian versions of the Fokker-Planck equation and the telegrapher's equation. As an example, it is shown how the non-Markovian nature changes the behavior of the driven linear process

Ambient Vibrations Measurements and 1D Site Response Modelling as a Tool for Soil and Building Properties Investigation

Directory of Open Access Journals (Sweden)

Sebastiano Imposa

2018-03-01

Full Text Available The safety of historic buildings heritage is an important task that becomes more substantial when the buildings are directed to educational purposes. The present study aims at evaluating the dynamic features of the Benedettini complex, an historic monastery located in downtown Catania, which is at present the headquarters of the humanistic studies department of the University of Catania. Both the building’s complex response to a seismic input and the soil-to-structure interaction were investigated using ambient noise recordings. The results point out a multiple dynamic behaviour of the monastery structure that shows several oscillation modes, whereas the identification of a single natural frequency can be observed in some sites where the structure can more freely oscillate. This observation is also confirmed by the variability of computed damping values that appear linked to the different rigidity of the structure, as a function of the either the longitudinal or transversal orientation of the investigated structural elements. Moreover, the comparison between the building’s fundamental period and spectral ratios frequencies, which were obtained from free field ambient noise measurements located outside the monastery, outline the presence of potential resonance effects between the site and structure during a seismic event. Numerical modelling of the local seismic response confirms the obtained experimental site frequencies, setting into evidence that higher amplification factors are reached in the same frequency range characterizing the building.

Distribution of flux-pinning energies in YBa2Cu3O7-δ and Bi2Sr2CaCu2O8+δ from flux noise

International Nuclear Information System (INIS)

Ferrari, M.J.; Johnson, M.; Wellstood, F.C.; Clarke, J.; Mitzi, D.; Rosenthal, P.A.; Eom, C.B.; Geballe, T.H.; Kapitulnik, A.; Beasley, M.R.

1990-01-01

The spectral density of the magnetic flux noise measured in high-temperature superconductors in low magnetic fields scales approximately as the inverse of the frequency and increases with temperature. We use the temperature and frequency dependence of the noise to determine the pinning energies of individual flux vortices in thermal equilibrium. The distribution of pinning energies peaks below 0.1 eV in YBa 2 Cu 3 O 7-δ and near 0.2 eV in Bi 2 Sr 2 CaCu 2 O 8+δ . The noise power is proportional to the ambient magnetic field, indicating that the vortex motion is uncorrelated

Crustal structure beneath Liaoning province and the Bohai Sea and its adjacent region in China based on ambient noise tomography

Science.gov (United States)

Pang, Guang-hua; Feng, Ji-Kun; Lin, Jun

2017-02-01

The velocity structure of the crust beneath Liaoning province and the Bohai sea in China was imaged using ambient seismic noise recorded by 73 regional broadband stations. All available three-component time series from the 12-month span between January and December 2013 were cross-correlated to yield empirical Green's functions for Rayleigh and Love waves. Phase-velocity dispersion curves for the Rayleigh waves and the Love waves were measured by applying the frequency-time analysis method. Dispersion measurements of the Rayleigh wave and the Love wave were then utilized to construct 2D phase-velocity maps for the Rayleigh wave at 8-35 s periods and the Love wave at 9-32 s periods, respectively. Both Rayleigh and Love phase-velocity maps show significant lateral variations that are correlated well with known geological features and tectonics units in the study region. Next, phase dispersion curves of the Rayleigh wave and the Love wave extracted from each cell of the 2D Rayleigh wave and Love wave phase-velocity maps, respectively, were inverted simultaneously to determine the 3D shear wave velocity structures. The horizontal shear wave velocity images clearly and intuitively exhibit that the earthquake swarms in the Haicheng region and the Tangshan region are mainly clustered in the transition zone between the low- and high-velocity zones in the upper crust, coinciding with fault zones, and their distribution is very closely associated with these faults. The vertical shear wave velocity image reveals that the lower crust downward to the uppermost mantle is featured by distinctly high velocities, with even a high-velocity thinner layer existing at the bottom of the lower crust near Moho in central and northern the Bohai sea along the Tanlu fault, and these phenomena could be caused by the intrusion of mantle material, indicating the Tanlu fault could be just as the uprising channel of deep materials.

Noise-induced annoyance from transportation noise: short-term responses to a single noise source in a laboratory.

Science.gov (United States)

Kim, Jaehwan; Lim, Changwoo; Hong, Jiyoung; Lee, Soogab

2010-02-01

An experimental study was performed to compare the annoyances from civil-aircraft noise, military-aircraft noise, railway noise, and road-traffic noise. Two-way within-subjects designs were applied in this research. Fifty-two subjects, who were naive listeners, were given various stimuli with varying levels through a headphone in an anechoic chamber. Regardless of the frequency weighting network, even under the same average energy level, civil-aircraft noise was the most annoying, followed by military-aircraft noise, railway noise, and road-traffic noise. In particular, penalties in the time-averaged, A-weighted sound level (TAL) of about 8, 5, and 5 dB, respectively, were found in the civil-aircraft, military-aircraft, and railway noises. The reason could be clarified through the high-frequency component and the variability in the level. When people were exposed to sounds with the same maximum A-weighted level, a railway bonus of about 3 dB was found. However, transportation noise has been evaluated by the time-averaged A-weighted level in most countries. Therefore, in the present situation, the railway bonus is not acceptable for railway vehicles with diesel-electric engines.

Near-ambient solid polymer fuel cell

Science.gov (United States)

Holleck, G. L.

1993-01-01

Fuel cells are extremely attractive for extraterrestrial and terrestrial applications because of their high energy conversion efficiency without noise or environmental pollution. Among the various fuel cell systems the advanced polymer electrolyte membrane fuel cells based on sulfonated fluoropolymers (e.g., Nafion) are particularly attractive because they are fairly rugged, solid state, quite conductive, of good chemical and thermal stability and show good oxygen reduction kinetics due to the low specific adsorption of the electrolyte on the platinum catalyst. The objective of this program is to develop a solid polymer fuel cell which can efficiently operate at near ambient temperatures without ancillary components for humidification and/or pressurization of the fuel or oxidant gases. During the Phase 1 effort we fabricated novel integral electrode-membrane structures where the dispersed platinum catalyst is precipitated within the Nafion ionomer. This resulted in electrode-membrane units without interfacial barriers permitting unhindered water diffusion from cathode to anode. The integral electrode-membrane structures were tested as fuel cells operating on H2 and O2 or air at 1 to 2 atm and 10 to 50 C without gas humidification. We demonstrated that cells with completely dry membranes could be self started at room temperature and subsequently operated on dry gas for extended time. Typical room temperature low pressure operation with unoptimized electrodes yielded 100 mA/cm(exp 2) at 0.5V and maximum currents over 300 mA/cm(exp 2) with low platinum loadings. Our results clearly demonstrate that operation of proton exchange membrane fuel cells at ambient conditions is feasible. Optimization of the electrode-membrane structure is necessary to assess the full performance potential but we expect significant gains in weight and volume power density for the system. The reduced complexity will make fuel cells also attractive for smaller and portable power supplies and as

Environmental noise and noise modelling-some aspects in Malaysian development

International Nuclear Information System (INIS)

Leong, Mohd Salman; Mohd Shafiek bin Hj Yaacob

1994-01-01

Environmental noise is of growing concern in Malaysia with the increasing awareness of the need for an environmental quality consistent with improved quality of life. While noise is one of the several elements in an Environmental Impact Assessment report, the degree of emphasis in the assessment is not as thorough as other aspects in the EIA study. The measurements, prediction (if at all any), and evaluation tended to be superficial. The paper presents a summary of correct noise descriptors and annoyance assessment parameters appropriate for the evaluation of environmental noise. The paper further highlights current inadequacies in the Environmental Quality Act for noise pollution, and annoyance assessment. Some examples of local noise pollution are presented. A discussion on environmental noise modelling is presented. Examples illustrating environmental noise modelling for a mining operation and a power station are given. It is the authors' recommendation that environmental noise modelling be made mandatory in all EIA studies such that a more definitive assessment could be realised

Annoyance of low frequency noise and traffic noise

DEFF Research Database (Denmark)

Mortensen, F.R.; Poulsen, Torben

2001-01-01

The annoyance of different low frequency noise sources was determined and compared to the annoyance from traffic noise. Twenty-two subjects participated in laboratory listening tests. The sounds were presented by loudspeakers in a listening room and the spectra of the low frequency noises were...

Shear wave velocity structure of the Anatolian Plate and surrounding regions using Ambient Noise Tomography

Science.gov (United States)

Delph, J. R.; Beck, S. L.; Zandt, G.; Biryol, C. B.; Ward, K. M.

2013-12-01

The Anatolian Plate consists of various lithospheric terranes amalgamated during the closure of the Tethys Ocean, and is currently extruding to the west in response to a combination of the collision of the Arabian plate in the east and the roll back of the Aegean subduction zone in the west. We used Ambient Noise Tomography (ANT) at periods structure of the Anatolian Plate. We computed a total of 13,779 unique cross-correlations using one sample-per-second vertical component broadband seismic data from 215 stations from 8 different networks over a period of 7 years to compute fundamental-mode Rayleigh wave dispersion curves following the method of Benson et al. (2007). We then inverted the dispersion data to calculate phase velocity maps for 11 periods from 8 s - 40 s throughout Anatolia and the Aegean regions (Barmin et al. 2001). Using smoothed Moho values derived from Vanacore et al. (2013) in our starting models, we inverted our dispersion curves using a linear least-squares iterative inversion scheme (Herrmann & Ammon 2004) to produce a 3-D shear-wave velocity model of the crust and uppermost mantle throughout Anatolia and the Aegean. We find a good correlation between our seismic shear wave velocities and paleostructures (suture zones) and modern deformation (basin formation and fault deformation). The most prominent crustal velocity contrasts occur across intercontinental sutures zones, resulting from the juxtaposition of the compositionally different basements of the amalgamated terranes. At shallow depths, seismic velocity contrasts correspond closely with surficial features. The Thrace, Cankiri and Tuz Golu basins, and accretionary complexes related to the closure of the Neotethys are characterized by slow shear wave velocities, while the Menderes and Kirsehir Massifs, Pontides, and Istanbul Zone are characterized by fast velocities. We find that the East Anatolia Plateau has slow shear-wave velocities, as expected due to high heat flow and active

Evaluating noise abatement measures using strategic noise maps

NARCIS (Netherlands)

Borst, H.C.; Miedema, H.M.E.; Laan, W.P.N. van der; Lohman, W.J.A.

2006-01-01

Noise annoyance due to transportation is widespread in industrialized countries and in urban areas in the developing countries. The European Noise Directive (END) requires an assessment of the noise situation as well as the formulation of action plans for the reduction of the number of people

Environmental Noise Exposure On Occupants In Naturally Ventilated Open-Plan Offices Case Of Selected Offices In Kumasi Ghana

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Koranteng

2015-08-01

Full Text Available The design of buildings in public educational institutions in Ghana predominantly adopts open-plan offices that are naturally ventilated with the aid of operable windows for reasons such as achieving adaptable spaces improved social climate and effective ventilation. However adoption of open-plan naturally ventilated offices in these educational institutions expose occupants to noise that emanates indoors and from outdoor sources which can interfere with and impede work performance. The study aimed at assessing noise exposure levels and occupants satisfaction with noise level in selected naturally ventilated open-plan offices in Ghana. The study employed an empirical assessment of the noise levels in and around three of the office buildings using a PCE222 Digital Sound Level Meter and a survey involving interviews to assess workers satisfaction of noise levels of the open-plan offices at the Kwame Nkrumah University of Science and Technology in Kumasi. The results show that mean outdoor noise levels for offices ranged from 11 per cent below to 5 per cent above the WHO permissible limits while mean indoor noise levels exceeded the limit by between 20-40 per cent during the course of the day. In spite of the high levels of noise occupants generally considered the overall noise level in their offices as acceptable. Likewise the results indicate that there are no significant differences in occupants exposure to noise from their various sitting positions in an office space and floor levels in an office building. The paper recommends strategies to manage and improve ambient noise quality within naturally ventilated open-plan office spaces in Ghana. The study will be of relevance as a useful guide to organizations and policy makers concerned with built environmental issues.

Noise annoys: effects of noise on breeding great tits depend on personality but not on noise characteristics

NARCIS (Netherlands)

Naguib, M.; Van Oers, K.; Braakhuis, A.; Griffioen, M.; De Goede, P.; Waas, J.R.

2013-01-01

Anthropogenic noise can have serious implications for animals, especially when they communicate acoustically. Yet, the impacts of noise may depend not only on noise characteristics but also on an individual's coping style or personality. We tested whether noise is more disturbing if it masks

Noise Configuration and fault zone anisotropy investigation from Taiwan Chelungpu-fault Deep Borehole Array

Science.gov (United States)

Hung, R. J.; Ma, K. F.; Song, T. R. A.; Nishida, K.; Lin, Y. Y.

2016-12-01

The Taiwan Chelungpu-fault Drilling Project was operated to understand the fault zone characteristics associated with the 1999 Chichi earthquake. Seven Borehole Seismometers (TCDPBHS) were installed through the identified fault zone to monitor the micro-seismic activities, as well as the fault-zone seismic structure properties. To understand the fault zone anisotropy and its possible temporal variations after the Chichi earthquake, we calculated cross-correlations of the noise at different stations to obtain cross correlation functions (CCFs) of the ambient noise field between every pair of the stations. The result shows that TCDP well site suffers from complex wavefield, and phase traveltime from CCF can't provide explicit result to determine the dominated wavefield. We first analyze the power density spectra and probability density functions of this array. We observe that the spectra show diurnal variation in the frequency band 1-25 Hz, suggesting human-generated sources are dominated in this frequency band. Then, we focus on the particle motion analysis at each CCF. We assume one component at a station plays as a visual source and compute the CCF tensor in other station components. The particle motion traces show high linearity which indicate that the dominated wavefield in our study area is body wave signals with the azimuth approximate to 60° from north. We also analyze the Fourier spectral amplitudes by rotating every 5 degrees in time domain to search for the maximum background energy distribution. The result shows that the spectral amplitudes are stronger at NE-SW direction, with shallow incident angles which are comparable with the CCF particle motion measurement. In order to obtain higher resolution about the dominated wavefield in our study area, we also used beamforming from surface station array to validate our results from CCF analysis. In addition to the CCF analysis to provide the noise configuration at the TCDPBHS site for further analysis on

Association of long-term exposure to community noise and traffic-related air pollution with coronary heart disease mortality.

Science.gov (United States)

Gan, Wen Qi; Davies, Hugh W; Koehoorn, Mieke; Brauer, Michael

2012-05-01

In metropolitan areas, road traffic is a major contributor to ambient air pollution and the dominant source of community noise. The authors investigated the independent and joint influences of community noise and traffic-related air pollution on risk of coronary heart disease (CHD) mortality in a population-based cohort study with a 5-year exposure period (January 1994-December 1998) and a 4-year follow-up period (January 1999-December 2002). Individuals who were 45-85 years of age and resided in metropolitan Vancouver, Canada, during the exposure period and did not have known CHD at baseline were included (n = 445,868). Individual exposures to community noise and traffic-related air pollutants, including black carbon, particulate matter less than or equal to 2.5 μm in aerodynamic diameter, nitrogen dioxide, and nitric oxide, were estimated at each person's residence using a noise prediction model and land-use regression models, respectively. CHD deaths were identified from the provincial death registration database. After adjustment for potential confounders, including traffic-related air pollutants or noise, elevations in noise and black carbon equal to the interquartile ranges were associated with 6% (95% confidence interval: 1, 11) and 4% (95% confidence interval: 1, 8) increases, respectively, in CHD mortality. Subjects in the highest noise decile had a 22% (95% confidence interval: 4, 43) increase in CHD mortality compared with persons in the lowest decile. These findings suggest that there are independent effects of traffic-related noise and air pollution on CHD mortality.

Salud ambiental: conceptos y actividades

Directory of Open Access Journals (Sweden)

Gonzalo A. Ordóñez

2000-03-01

Full Text Available La finalidad del trabajo es aportar información y propuestas conceptuales que faciliten la tarea de quienes tienen a su cargo la sistematización institucional de la salud ambiental. Se hace un análisis de la noción de "ambiente" para la cual se sugiere una definición, y se examina el lugar de la salud ambiental en el contexto de los problemas ambientales y sus vertientes "verde" y "azul". Se examinan denominaciones equivalentes de salud ambiental y se introducen los servicios de salud ambiental. Se proporcionan varias definiciones y se da la oficial de salud ambiental adoptada por la OMS en Sofía, Bulgaria (1993. A continuación se transcriben las áreas básicas que a la salud ambiental le han asignado diversas organizaciones o reuniones, como la OPS, la OMS, el Programa 21 y otros. A partir de aquí se construye un repertorio bastante completo de áreas y subáreas y se encuentra que todos los listados son, en realidad, una reunión asistemática de tres tipos de constituyentes: determinantes (factores o hechos de la realidad física, procesos (conjuntos de intervenciones y funciones (conjuntos de acciones de gestión, los cuales pueden enfocarse matricialmente y llevan a individualizar actividades de los servicios de salud ambiental. Se proponen unas reglas de operación que permiten, en una especie de álgebra, construir expresiones para especificar con precisión las actividades y sus agregados. De este modo se logra disponer de un lenguaje simbólico común que puede ayudar a la intercomunicación, enseñanza e investigación en el ámbito de la salud ambiental.

Ambient and Wake Turbulence Measurements at Marine Energy Sites from a Five Beam AD2CP

Science.gov (United States)

Guerra, M. A.; Thomson, J. M.

2016-02-01

Ambient turbulence at hydrokinetic energy sites is a key input for turbine design and for their performance determination. Added turbulence from rotating blades to the flow affects the environment surrounding the turbine and has an impact in turbine array distribution. We present two approaches of turbulence measurements: stationary and drifting. Stationary measurements allow for time and frequency analysis of turbulent velocities, while drifting measurements give a spatial characterization of turbulence. For both approaches we used the new five beam Nortek Signature AD2CP. This instrument captures turbulent flow along the water column at high sampling rates (8 Hz) with low Doppler noise level; the use of five beams also makes it possible to fully calculate the Reynolds Stresses. Both sets of measurements require Doppler noise removal for consistent results. Stationary measurements of ambient turbulence were carried out in Admiralty Inlet, WA, in May 2015. The Signature was deployed up looking on a sea spider tripod in a 50 m depth tidal channel during two tidal cycles. This data set allowed us to characterize the turbulence in terms of spectra and Reynolds Stresses in order to evaluate the turbulent kinetic energy balance along the water column and to compare results to other tidal energy sites with similar characteristics where turbulence measurements were taken as well. Drifting measurements of ambient and wake turbulence were conducted in the vicinity of the ORPC RivGen® turbine deployed on the Kvichak River in Alaska in July 2015. The Signature was mounted down looking onboard an anchor buoy equipped with two GPS data receivers for georefference. The cross-sectional river span was covered by releasing the drifter at different positions across the river. More than 300 drifts were performed to spatially characterize turbulence before and after turbine's deployment and grid connection. Results indicate an increased turbulent wake extending up to 75 m downstream

Listening to the Deep: live monitoring of ocean noise and cetacean acoustic signals.

Science.gov (United States)

André, M; van der Schaar, M; Zaugg, S; Houégnigan, L; Sánchez, A M; Castell, J V

2011-01-01

The development and broad use of passive acoustic monitoring techniques have the potential to help assessing the large-scale influence of artificial noise on marine organisms and ecosystems. Deep-sea observatories have the potential to play a key role in understanding these recent acoustic changes. LIDO (Listening to the Deep Ocean Environment) is an international project that is allowing the real-time long-term monitoring of marine ambient noise as well as marine mammal sounds at cabled and standalone observatories. Here, we present the overall development of the project and the use of passive acoustic monitoring (PAM) techniques to provide the scientific community with real-time data at large spatial and temporal scales. Special attention is given to the extraction and identification of high frequency cetacean echolocation signals given the relevance of detecting target species, e.g. beaked whales, in mitigation processes, e.g. during military exercises. Copyright © 2011. Published by Elsevier Ltd.

The effects of noise reduction technologies on the acceptance of background noise.

Science.gov (United States)

Lowery, Kristy Jones; Plyler, Patrick N

2013-09-01

Directional microphones (D-Mics) and digital noise reduction (DNR) algorithms are used in hearing aids to reduce the negative effects of background noise on performance. Directional microphones attenuate sounds arriving from anywhere other than the front of the listener while DNR attenuates sounds with physical characteristics of noise. Although both noise reduction technologies are currently available in hearing aids, it is unclear if the use of these technologies in isolation or together affects acceptance of noise and/or preference for the end user when used in various types of background noise. The purpose of the research was to determine the effects of D-Mic, DNR, or the combination of D-Mic and DNR on acceptance of noise and preference when listening in various types of background noise. An experimental study in which subjects were exposed to a repeated measures design was utilized. Thirty adult listeners with mild sloping to moderately severe sensorineural hearing loss participated (mean age 67 yr). Acceptable noise levels (ANLs) were obtained using no noise reduction technologies, D-Mic only, DNR only, and the combination of the two technologies (Combo) for three different background noises (single-talker speech, speech-shaped noise, and multitalker babble) for each listener. In addition, preference rankings of the noise reduction technologies were obtained within each background noise (1 = best, 3 = worst). ANL values were significantly better for each noise reduction technology than baseline; and benefit increased significantly from DNR to D-Mic to Combo. Listeners with higher (worse) baseline ANLs received more benefit from noise reduction technologies than listeners with lower (better) baseline ANLs. Neither ANL values nor ANL benefit values were significantly affected by background noise type; however, ANL benefit with D-Mic and Combo was similar when speech-like noise was present while ANL benefit was greatest for Combo when speech spectrum noise was

MODIFICANDO O AMBIENTE ESCOLAR ATRAVÉS DO PROJETO MEIO AMBIENTE: CULTIVANDO E CONHECENDO AS PLANTAS

Directory of Open Access Journals (Sweden)

Letícia Caroline Lopes

2011-07-01

Full Text Available O presente trabalho intitulado “MODIFICANDO O AMBIENTE ESCOLAR ATRAVÉS DO PROJETO MEIO AMBIENTE: CULTIVANDO E CONHECENDO AS PLANTAS” tem como desígnio apresentar o desenvolvimento do projeto “meio ambiente: cultivando e conhecendo as plantas”, no qual teve como proposta sensibilizar os alunos sobre a importância e preservação do meio ambiente através da prática e modificação do ambiente escolar, onde procurou-se utilizar materiais reciclados, tais como, garrafas pet, pneus velhos, carreteis de fios de eletricidade, e também mudas de arvore, plantas e hortaliças. Desta forma buscou se utilizar da criatividade dos envolvidos no processo para a transformação do ambiente escolar seco e vazio, para uma ambiente alegre, e acolhedor. O projeto foi elaborado pelas professoras da Extensão Betel, e aplicado em parceria com acadêmicos do sexto semestre do curso de Licenciatura em Pedagogia da Universidade do Estado do Mato Grosso (UNEMAT, campus de Sinop. Tendo como proposta a interdisciplinaridade, o projeto foi divido em três eixos orientados pelas professoras Edneuza Alves Trugillo, Sinóvia Rauber e Mariza Kreinner, abrangendo assim alunos e professoras de duas turmas de 2º Ano do Ensino Fundamental, e acadêmicos e professores da Universidade, os eixos foram arborização, jardinagem e horta, onde teve a duração de aproximadamente dois meses. A finalização das práticas obteve resultados satisfatórios e objetivos alcançados, tanto pela sensibilização dos alunos sobre a preservação e importância do meio-ambiente, quanto pela prática de intervenção pelos acadêmicos envolvidos no processo, que em coletividade conseguiram modificar o ambiente escolar através do objetivo do projeto, meio-ambiente, proporcionando assim um enriquecimento na formação acadêmica enquanto práticas pedagógicas.

Community noise

Science.gov (United States)

Bragdon, C. R.

Airport and community land use planning as they relate to airport noise reduction are discussed. Legislation, community relations, and the physiological effect of airport noise are considered. Noise at the Logan, Los Angeles, and Minneapolis/St. Paul airports is discussed.

Educação ambiental na escola: a perspectiva estudantil sobre o meio ambiente e a propaganda ambiental na internet

Directory of Open Access Journals (Sweden)

Fernanda Reis de Pinho Tavares

2005-01-01

Full Text Available Este trabalho visa mostrar as idéias dos estudantes sobre um tema - a propaganda - refletindo como ela se insere na questão ambiental. Também abordamos como os alunos percebem questões como as relações, empresa, meio ambiente e sociedade. Foi realizado em uma oficina de Educação Ambiental, em uma escola particular de Lagoa Santa - MG, durante os meses de junho e julho de 2004. Analisaram-se sites de diversas empresas e ONG's (Organizações Não Governamentais. Em sua maioria os estudantes conseguiram posicionar-se criticamente em relação às entidades investigadas.

Noise Estimation and Quality Assessment of Gaussian Noise Corrupted Images

Science.gov (United States)

Kamble, V. M.; Bhurchandi, K.

2018-03-01

Evaluating the exact quantity of noise present in an image and quality of an image in the absence of reference image is a challenging task. We propose a near perfect noise estimation method and a no reference image quality assessment method for images corrupted by Gaussian noise. The proposed methods obtain initial estimate of noise standard deviation present in an image using the median of wavelet transform coefficients and then obtains a near to exact estimate using curve fitting. The proposed noise estimation method provides the estimate of noise within average error of +/-4%. For quality assessment, this noise estimate is mapped to fit the Differential Mean Opinion Score (DMOS) using a nonlinear function. The proposed methods require minimum training and yields the noise estimate and image quality score. Images from Laboratory for image and Video Processing (LIVE) database and Computational Perception and Image Quality (CSIQ) database are used for validation of the proposed quality assessment method. Experimental results show that the performance of proposed quality assessment method is at par with the existing no reference image quality assessment metric for Gaussian noise corrupted images.

Report on inter-noise 99; Inter-noise 99 sanka hokok

Energy Technology Data Exchange (ETDEWEB)

Koike, H. [Japan Automobile Research Institute Inc., Tsukuba (Japan)

2000-04-01

Inter-Noise (International Congress on Noise Control Engineering) is a society on noise/vibration and the control technology. Inter-Noise 99 was held on December 6, 7 and 8, 1999, at Fort Lauderdale, Florida, the U.S. The theme was Noise Control in the New Millennium. The number of the participants registered was 555 (151 from the U.S., 89 from Japan, 248 from European countries, and 69 from Asian/other countries). Dr. Harold Marshall gave a keynote lecture titled Noise Control by Design in the 21st Century - An Architectural Acoustic Perspective. From a standpoint of architectural acoustics, he stated the perspective, subjects, and course of the technical development pertaining to technologies needed in the 21st century. The papers read are mostly from the following fields: measuring technology, military exercise noise, modeling, forecast and simulation, aerodynamic/underwater sound, etc. In the session on the tire noise where the author read a paper, 14 papers were read. The number of the papers read was more than that in 1998, probably influenced by the tire noise regulation in Europe and Japan. (translated by NEDO)

Noise frame duration, masking potency and whiteness of temporal noise

OpenAIRE

Kukkonen, Helja; Rovamo, Jyrki; Donner, Kristian; Tammikallio, Marja; Raninen, Antii

2002-01-01

PURPOSE. Because of the limited contrast range, increasing the duration of the noise frame is often the only option for increasing the masking potency of external, white temporal noise. This, however, reduces the high-frequency cutoff beyond which noise is no longer white. This study was conducted to determine the longest noise frame duration that produces the strongest masking effect and still mimics white noise on the detection of sinusoidal flicker. \\ud \\ud METHODS. Contrast energy thresho...

Noise

Science.gov (United States)

Noise is all around you, from televisions and radios to lawn mowers and washing machines. Normally, you ... sensitive structures of the inner ear and cause noise-induced hearing loss. More than 30 million Americans ...

Multi-Gas analysis of ambient air using FTIR spectroscopy over Mexico City

Energy Technology Data Exchange (ETDEWEB)

Grutter, Michel [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico (UNAM), Mexico, D.F. (Mexico)

2003-01-01

A Fourier Transform Infrared (FTIR) spectrometer was used to analyze the composition of ambient air at a specific site in Mexico City metropolitan area. A continuous flow of air was passed through a multi-pass cell and the absorption spectra were collected over a period of two weeks. Quantitative analysis was performed by means of the classical-least square (CLS) method using synthetically generated spectra as references and calibration sources. Ambient levels of CO, CO{sup 2}, CH{sub 4} and N{sub 2}O are reported with a time resolution of five minutes for September 2001, showing interesting results in their diurnal patterns. Comments on the precision, detection limits and signal to noise of the instrument are included for the evaluation of this technique. Water concentrations were estimated and compared with those obtained with a relative humidity sensor. The technique of extractive FTIR for ambient trace gas monitoring was utilized in Mexico for the fist time and some potential applications are given. [Spanish] Se utilizo un espectrometro en el infrarrojo por transformadas de Fourier (FTIR) para analizar la composicion de aire ambiente en un sitio de la zona metropolitana de la Ciudad de Mexico. Para ello se introdujo un flujo constante de aire a una celda de gases de paso multiple y se colectaron los espectros durante un periodo de dos semanas. Para el analisis cuantitativo, se aplico el metodo clasico de minimos cuadrados (CLS) utilizando espectros sinteticos como referencias y fuentes de calibracion. Se observaron patrones interesantes en los niveles ambientales de CO, CO{sup 2}, CH{sub 4} y N{sub 2}O, los cuales son reportados con una resolucion temporal de cinco minutos para el mes de septiembre del 2001. En la evaluacion de esta tecnica se incluyen comentarios sobre la precision, los limites de deteccion, asi como de la relacion senal/ruido del instrumento. Se estimaron concentraciones de vapor de agua a traves de sus absorciones en el infrarrojo y se

COMPLEJIDAD AMBIENTAL: PROPUESTAS ÉTICAS EMERGENTES DEL PENSAMIENTO AMBIENTAL LATINOAMERICANO

Directory of Open Access Journals (Sweden)

Noguera de Echeverri Ana Patricia

2008-07-01

Full Text Available En este artículo, se recogen las propuestas ético ambientales más importantes de la Escuela de Pensamiento Ambiental Latinoamericano, que ha ido construyéndose desde hace 30 años. Se destacan autores de primera línea en el campo de la construcción de Pensamiento Ambiental filosófico, como el Filósofo y Pensador Colombiano, de trascendencia latinoamericana, Augusto Ángel Maya, quien plantea la posibilidad de construir una Filosofía Ambiental Ético estética, dado que la Filosofía Moderna ha sido Metafísica, aún en sus corrientes empiristas, positivistas y neopositivistas. Se destaca la obra de Enrique Leff, mexicano, que propone los conceptos de Complejidad y Saber Ambiental, como puntos de partida de una ética en la educación, la ciencia y la tecnología, dentro de unas relaciones sistémicas y holísticas. Igualmente la propuesta ético estética compleja de Julio Carrizoza, colombiano, se hace presente en este ensayo, como una propuesta política fundamental ante problemas colombianos como son la violencia y la exclusión. Las propuestas de Filósofos colombianos de gran importancia en el campo de la Filosofía Política y Moral, que han desembocado en la propuesta de una Ética Ambiental, Pública y Comunicativa, como es el caso de Guillermo Hoyos Vásquez y de otros pensadores tanto de Colombia como de otros países latinoamericanos, se presentan en este espacio, con el fin de recoger de manera crítica nuestras ideas acerca de la posibilidad de una ética ambiental, es decir una ética descentrada, sin sujeto y sin objeto, una ética sistémica, donde los valores se construyen en las relaciones y donde la intricada trama de la vida, que ha venido construyéndose desde hace más de 2.500 millones de años, y de la cual somos meros hilos, pasa de ser objeto a ser valor primero en su más genuino sentido.

The role of Urbis' noise and noise effects maps in local policy

NARCIS (Netherlands)

Borst, H.C.

2001-01-01

An important aspect of the EU noise policy is mapping of noise and noise effects and the formulation of noise action plans. In the Netherlands, due to the new policy on noise (MIG), the municipalities will be responsible for the formulation of a local noise policy. An instrument for the assessment

Det ambientes fænomenologi

DEFF Research Database (Denmark)

Walther-Hansen, Mads

2014-01-01

Det ambiente: sansning, medialisering, omgivelse er et aktuelt og ambitiøst værk. Bogen skildrer hvordan ambiente fænomener har fået en stigende betydning i den moderne verden, og redegør for måden hvorpå det ambiente virker ind på hele vores oplevelseskultur. Det er en levende, uprætentiøs og frem...

Study of environmental noise in a BWR plant like the Nuclear Power Plant Laguna Verde; Estudio de ruido ambiental en una planta BWR como la Central Nuclear Laguna Verde

Energy Technology Data Exchange (ETDEWEB)

Tijerina S, F.; Cruz G, M.; Amador C, C., E-mail: francisco.tijerina@cfe.gob.mx [Comision Federal de Electricidad, Central Nucleoelectrica Laguna Verde, Subgerencia de Ingenieria, Carretera Cardel-Nautla Km. 42.5, Alto Lucero, Veracruz (Mexico)

2013-10-15

In all industry type the health costs generated by the noise are high, because the noise can cause nuisance and to harm the capacity to work when causing tension and to perturb the concentration, and in more severe cases to reach to lose the sense of the hearing in the long term. The noise levels in the industry have been designated for the different types of use like residential, commercial, and industrial and silence areas. The noise can cause accidents when obstructing the communications and alarm signs. For this reason the noise should be controlled and mitigated, at a low level as reasonably is possible, taking into account that the noise is an acoustic contamination. The present study determines a bases line of the environmental noise levels in a nuclear power plant BWR-5 as Laguna Verde, (like reference) to be able to determine and to give pursuit to the possible solutions to eliminate or to limit the noise level in the different job areas. The noise levels were registered with a meter of integrative noise level (sonometer) and areas of noise exposure levels mapping the general areas in the buildings were established, being the registered maximum level of 96.94 dba in the building of the Reactor-elevation 0.65 m under the operation conditions of Extended Power Up rate (EPU) of 120% PTN. Knowing that the exposition to noises and the noise dose in the job place can influence in the health and in the safety of the workers, are extensive topics that they should be analyzed for separate as they are: to) the effects in the health of the exposure to the noise, b) how measuring the noise, c) the methods and technologies to combat and to control the noise in the industry by part of engineering area and d) the function of the industrial safety bodies as delegates of the health and safety in the task against the noise in the job. (author)

Noise in Optical Amplifiers

DEFF Research Database (Denmark)

Jeppesen, Palle

1997-01-01

Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived.......Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived....

Persuasion in Ambient Intelligence

NARCIS (Netherlands)

Kaptein, M.C.; Markopoulos, P.; Ruyter, de B.E.R.; Aarts, E.H.L.

2010-01-01

Although the field of persuasive technologies has lately attracted a lot of attention, only recently the notion of ambient persuasive technologies was introduced. Ambient persuasive technologies can be integrated into every aspect of life, and as such have greater persuasive power than the

The sound of high winds. The effect of atmospheric stability on wind turbine sound and microphone noise

International Nuclear Information System (INIS)

Van den Berg, G.P.

2006-01-01

In this thesis issues are raised concerning wind turbine noise and its relationship to altitude dependent wind velocity. The following issues are investigated: what is the influence of atmospheric stability on the speed and sound power of a wind turbine?; what is the influence of atmospheric stability on the character of wind turbine sound?; how widespread is the impact of atmospheric stability on wind turbine performance: is it relevant for new wind turbine projects; how can noise prediction take this stability into account?; what can be done to deal with the resultant higher impact of wind turbine sound? Apart from these directly wind turbine related issues, a final aim was to address a measurement problem: how does wind on a microphone affect the measurement of the ambient sound level?

Evaluation of noise pollution in urban traffic hubs—Noise maps and measurements

International Nuclear Information System (INIS)

Fiedler, Paulo Eduardo Kirrian; Zannin, Paulo Henrique Trombetta

2015-01-01

A study was made of some of the main traffic hubs in a Latin American metropolis, in order to determine the presence or absence of noise by means of noise measurements and acoustic mapping. To characterize noise in the evaluated road stretches, 232 measurements were taken at different points. The Predictor software package was used for the noise mapping calculations. Noise sensitive areas, e.g., hospitals, were identified in the evaluated road stretches. Noise maps were calculated for two hospitals, showing the current levels of noise that reach their facades. Hypothetical scenarios were simulated by making changes in the composition of traffic and total number of vehicles, and an assessment was made of the potential influence of these modifications in reducing the noise levels reaching the facades of the buildings in question. The simulations indicated that a 50% reduction in total traffic flow, or a 50% reduction in heavy vehicle traffic flow, would reduce the noise levels by about 3 dB(A). - Highlights: • Evaluation of noise pollution in urban traffic hubs • Street systems • Environmental noise impacts • Noise mapping

Evaluation of noise pollution in urban traffic hubs—Noise maps and measurements

Energy Technology Data Exchange (ETDEWEB)

Fiedler, Paulo Eduardo Kirrian; Zannin, Paulo Henrique Trombetta, E-mail: paulo.zannin@pesquisador.cnpq.br

2015-02-15

A study was made of some of the main traffic hubs in a Latin American metropolis, in order to determine the presence or absence of noise by means of noise measurements and acoustic mapping. To characterize noise in the evaluated road stretches, 232 measurements were taken at different points. The Predictor software package was used for the noise mapping calculations. Noise sensitive areas, e.g., hospitals, were identified in the evaluated road stretches. Noise maps were calculated for two hospitals, showing the current levels of noise that reach their facades. Hypothetical scenarios were simulated by making changes in the composition of traffic and total number of vehicles, and an assessment was made of the potential influence of these modifications in reducing the noise levels reaching the facades of the buildings in question. The simulations indicated that a 50% reduction in total traffic flow, or a 50% reduction in heavy vehicle traffic flow, would reduce the noise levels by about 3 dB(A). - Highlights: • Evaluation of noise pollution in urban traffic hubs • Street systems • Environmental noise impacts • Noise mapping.

Environmental noise exposure, early biological risk and mental health in nine to ten year old children: a cross-sectional field study

Directory of Open Access Journals (Sweden)

Stansfeld Stephen A

2011-05-01

Full Text Available Abstract Background Previous research suggests that children born prematurely or with a low birth weight are more vulnerable to the mental health effects of ambient neighbourhood noise; predominantly road and rail noise, at home. This study used data from the Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH study to see if this finding extends to aircraft and road traffic noise at school. Methods Children and their parents from schools around three European airports were selected to represent a range of aircraft and road traffic noise exposure levels. Birth weight and gestation period were merged to create a dichotomous variable assessing 'early biological risk'. Mental health was assessed using the Strengths and Difficulties Questionnaire (SDQ. Complete data were available for 1900 primary school children. Results Children who were 'at risk' (i.e. low birth weight or premature birth were rated as having more conduct problems and emotional symptoms and poorer overall mental health than children not at risk. However, there was no interaction between aircraft or road traffic noise exposure at school and early biological risk. Conclusions Data from the RANCH study suggests that children with early biological risk are not more vulnerable to the effects of aircraft or road traffic noise at school on mental health than children without this risk; however they are more likely to have mental ill-health.

Adaptive EMG noise reduction in ECG signals using noise level approximation

Science.gov (United States)

Marouf, Mohamed; Saranovac, Lazar

2017-12-01

In this paper the usage of noise level approximation for adaptive Electromyogram (EMG) noise reduction in the Electrocardiogram (ECG) signals is introduced. To achieve the adequate adaptiveness, a translation-invariant noise level approximation is employed. The approximation is done in the form of a guiding signal extracted as an estimation of the signal quality vs. EMG noise. The noise reduction framework is based on a bank of low pass filters. So, the adaptive noise reduction is achieved by selecting the appropriate filter with respect to the guiding signal aiming to obtain the best trade-off between the signal distortion caused by filtering and the signal readability. For the evaluation purposes; both real EMG and artificial noises are used. The tested ECG signals are from the MIT-BIH Arrhythmia Database Directory, while both real and artificial records of EMG noise are added and used in the evaluation process. Firstly, comparison with state of the art methods is conducted to verify the performance of the proposed approach in terms of noise cancellation while preserving the QRS complex waves. Additionally, the signal to noise ratio improvement after the adaptive noise reduction is computed and presented for the proposed method. Finally, the impact of adaptive noise reduction method on QRS complexes detection was studied. The tested signals are delineated using a state of the art method, and the QRS detection improvement for different SNR is presented.

The Assessment of Noise Exposure and Noise Annoyance at a Petrochemical Company

Directory of Open Access Journals (Sweden)

S. Farhang Dehghan

2013-12-01

.Conclusion: Based on the obtained results of investigating the noise level (objective exposure as well as the noise annoyance (subjective exposure at the studied company, it is necessary to adopt the management –technical noise reduction measures at manufacturing sectors as the personal noise exposure and environmental noise exposure and also noise personal exposure of administrative staff can be decreased.

Noise pollution resources compendium

Science.gov (United States)

1973-01-01

Abstracts of reports concerning noise pollution are presented. The abstracts are grouped in the following areas of activity: (1) sources of noise, (2) noise detection and measurement, (3) noise abatement and control, (4) physical effects of noise and (5) social effects of noise.

Solar noise storms

CERN Document Server

Elgaroy, E O

2013-01-01

Solar Noise Storms examines the properties and features of solar noise storm phenomenon. The book also presents some theories that can be used to gain a better understanding of the phenomenon. The coverage of the text includes topics that cover the features and behavior of noise storms, such as the observable features of noise storms; the relationship between noise storms and the observable features on the sun; and ordered behavior of storm bursts in the time-frequency plane. The book also covers the spectrum, polarization, and directivity of noise storms. The text will be of great use to astr

Variations of local seismic response in Benevento (Southern Italy) using earthquakes and ambient noise recordings

Science.gov (United States)

Improta, Luigi; di Giulio, Giuseppe; Rovelli, Antonio

The city of Benevento (Southern Italy) has been repeatedly struck by large historical earthquakes. A heterogeneous geologic structure and widespread soft soil conditions make the estimation of site effects crucial for the seismic hazard assessment of the city. From 2000 until 2004, we installed seismic stations to collect earthquake data over zones with different geological conditions. Despite the high level of urban noise, we recorded more than 150 earthquakes at twelve sites. This data set yields the first, well documented experimental evidence for weak to moderate local amplifications. We investigated site effects primarily by the classical spectral ratio technique (CSR) using a rock station placed on the Benevento hill as reference. All sites in the Calore river valley and in the eastern part of the Benevento hill show a moderate high-frequency (f > 4 Hz) amplification peak. Conversely, sites in the Sabato river valley share weak-to-moderate amplification in a wide frequency band (from 1-2 to 7-10 Hz), without evident frequency peaks. Application of no-reference-site techniques to earthquake and noise data confirms the results of the CSRs in the sites of the Calore river valley and of the eastern part of the Benevento hill, but fails in providing indications for site effects in the Sabato river valley, being the H/V ratios nearly flat. One-dimensional modeling indicates that the ground motion amplification can be essentially explained in terms of a vertically varying geologic structure. High-frequency narrow peaks are caused by the strong impedance contrast existing between near-surface soft deposits and stiff cemented conglomerates. Conversely, broad-band amplifications in the Sabato river valley are likely due to a more complex layering with weak impedance contrasts both in the shallow and deep structure of the valley.

Low noise constant current source for bias dependent noise measurements

International Nuclear Information System (INIS)

Talukdar, D.; Bose, Suvendu; Bardhan, K. K.; Chakraborty, R. K.

2011-01-01

A low noise constant current source used for measuring the 1/f noise in disordered systems in ohmic as well as nonohmic regime is described. The source can supply low noise constant current starting from as low as 1 μA to a few tens of milliampere with a high voltage compliance limit of around 20 V. The constant current source has several stages, which can work in a standalone manner or together to supply the desired value of load current. The noise contributed by the current source is very low in the entire current range. The fabrication of a low noise voltage preamplifier modified for bias dependent noise measurements and based on the existing design available in the MAT04 data sheet is also described.

Algorithms in ambient intelligence

NARCIS (Netherlands)

Aarts, E.H.L.; Korst, J.H.M.; Verhaegh, W.F.J.; Weber, W.; Rabaey, J.M.; Aarts, E.

2005-01-01

We briefly review the concept of ambient intelligence and discuss its relation with the domain of intelligent algorithms. By means of four examples of ambient intelligent systems, we argue that new computing methods and quantification measures are needed to bridge the gap between the class of

Proceedings of the 2009 spring noise conference : noise awareness : supporting sound partnerships

International Nuclear Information System (INIS)

2009-01-01

This conference provided a forum for industry, government, public, academics and acoustical professionals to discuss innovations in environmental and occupational noise identification, measurement, regulation and control. In addition to raising awareness about expanding noise issues, the conference objectives were to promote responsible industrial development and to identify strategies for reducing workplace noise exposure. The papers focused on research, developments and case studies and highlighted current issues and advancements in technology and software. Speakers from around the world discussed topics ranging from occupational noise issues to low frequency. The 8 sessions were entitled: (1) plenary session, (2) architecture, community planning and public health: effects of noise and noise control, (3) modeling, measurement and technology; (4) noise awareness and education: public, occupational and industrial, (5) regulations and economics: bylaws, legislation and the economics of noise control; (6) student papers, (7) vibration, industrial noise, transportation noise and occupational noise control, and (8) lunch speakers. The conference featured 46 presentations, of which 19 have been catalogued separately for inclusion in this database. refs., tabs., figs.

Noise in strong laser-atom interactions: Phase telegraph noise

International Nuclear Information System (INIS)

Eberly, J.H.; Wodkiewicz, K.; Shore, B.W.

1984-01-01

We discuss strong laser-atom interactions that are subjected to jump-type (random telegraph) random-phase noise. Physically, the jumps may arise from laser fluctuations, from collisions of various kinds, or from other external forces. Our discussion is carried out in two stages. First, direct and partially heuristic calculations determine the laser spectrum and also give a third-order differential equation for the average inversion of a two-level atom on resonance. At this stage a number of general features of the interaction are able to be studied easily. The optical analog of motional narrowing, for example, is clearly predicted. Second, we show that the theory of generalized Poisson processes allows laser-atom interactions in the presence of random telegraph noise of all kinds (not only phase noise) to be treated systematically, by means of a master equation first used in the context of quantum optics by Burshtein. We use the Burshtein equation to obtain an exact expression for the two-level atom's steady-state resonance fluorescence spectrum, when the exciting laser exhibits phase telegraph noise. Some comparisons are made with results obtained from other noise models. Detailed treatments of the effects ofmly jumps, or as a model of finite laser bandwidth effects, in which the laser frequency exhibits random jumps. We show that these two types of frequency noise can be distinguished in light-scattering spectra. We also discuss examples which demonstrate both temporal and spectral motional narrowing, nonexponential correlations, and non-Lorentzian spectra. Its exact solubility in finite terms makes the frequency-telegraph noise model an attractive alternative to the white-noise Ornstein-Uhlenbeck frequency noise model which has been previously applied to laser-atom interactions

Sistemas de gestión ambiental normalizados

OpenAIRE

Fronti de García, Luisa; Pahlen, Ricardo José María; D’Onofrio, Paula Alejandra

2004-01-01

La contabilidad ambiental presupone la existencia de un sistema de gestión ambiental. Dentro del sistema integral de la organización, el sistema de gestión ambiental permite la obtención de información oportuna y segura. Podríamos definir el sistema de gestión ambiental de un ente como el conjunto de medidas destinadas a prevenir el impacto negativo de las actividades del ente sobre el medio ambiente. El sistema de gestión ambiental (SGA) es aquella parte del sistema de gestión total que incl...

Background Noise Reduction Using Adaptive Noise Cancellation Determined by the Cross-Correlation

Science.gov (United States)

Spalt, Taylor B.; Brooks, Thomas F.; Fuller, Christopher R.

2012-01-01

Background noise due to flow in wind tunnels contaminates desired data by decreasing the Signal-to-Noise Ratio. The use of Adaptive Noise Cancellation to remove background noise at measurement microphones is compromised when the reference sensor measures both background and desired noise. The technique proposed modifies the classical processing configuration based on the cross-correlation between the reference and primary microphone. Background noise attenuation is achieved using a cross-correlation sample width that encompasses only the background noise and a matched delay for the adaptive processing. A present limitation of the method is that a minimum time delay between the background noise and desired signal must exist in order for the correlated parts of the desired signal to be separated from the background noise in the crosscorrelation. A simulation yields primary signal recovery which can be predicted from the coherence of the background noise between the channels. Results are compared with two existing methods.

Classical noise, quantum noise and secure communication

International Nuclear Information System (INIS)

Tannous, C; Langlois, J

2016-01-01

Secure communication based on message encryption might be performed by combining the message with controlled noise (called pseudo-noise) as performed in spread-spectrum communication used presently in Wi-Fi and smartphone telecommunication systems. Quantum communication based on entanglement is another route for securing communications as demonstrated by several important experiments described in this work. The central role played by the photon in unifying the description of classical and quantum noise as major ingredients of secure communication systems is highlighted and described on the basis of the classical and quantum fluctuation dissipation theorems. (review)

Contabilidade ambiental o passaporte para a competitividade

Directory of Open Access Journals (Sweden)

Maria Elisabeth Pereira Kraemer

2002-03-01

Full Text Available Como todos os problemas ambientais provocaram grandes danos irreversíveis, que incidiram e incidem agora em todos os países subdesenvolvidos e desenvolvidos, nasce, então, como necessidade imperiosa, introduzir nos nossos sistemas econômicos a Contabilidade Ambiental, pois as organizações, até alguns anos atrás, preocupavam-se apenas com a eficiência dos sistemas produtivos. Chegamos a "era da revolução ambiental", e o ambiente não somente aparece como um conjunto de problemas relativos ao controle da contaminação, mas representa um custo no crescimento econômico. Neste sentido, o contador precisa de uma formação que se estenda além dos limites das técnicas e dos procedimentos. É necessário acrescentar o registro contábil do meio ambiente, dada a velocidade de sua afetação e a influência do mundo atual na utilização e disposição dos recursos naturais. Deve ser considerado como um dos princípios contábeis, onde é um desafio para a contabilidade. Precisa ser considerada como uma ciência contábil integrada, pois com a ciência ecológica e outras ciências são responsáveis pela natureza onde devem ser aplicados critérios de proteção ambiental, demonstrando que os recursos naturais constituem nosso principal capital. Partindo dessa premissa é que este trabalho está enfocando os seguintes tópicos: Responsabilidade Social da Empresa; A Empresa e o Meio Ambiente; Gestão Ambiental; Sistema de Gestão Ambiental; Ações para Preservar o Meio Ambiente - O Protocolo Verde, A Contabilidade, Custos Ambientais, Ativo Ambiental, Passivo Ambiental, Patrimônio Ambiental, Contabilidade Ambiental e Contabilidade Ambiental - o Passaporte para a Competitividade.

Relaxometry imaging of superparamagnetic magnetite nanoparticles at ambient conditions

Science.gov (United States)

Finkler, Amit; Schmid-Lorch, Dominik; Häberle, Thomas; Reinhard, Friedemann; Zappe, Andrea; Slota, Michael; Bogani, Lapo; Wrachtrup, Jörg

We present a novel technique to image superparamagnetic iron oxide nanoparticles via their fluctuating magnetic fields. The detection is based on the nitrogen-vacancy (NV) color center in diamond, which allows optically detected magnetic resonance (ODMR) measurements on its electron spin structure. In combination with an atomic-force-microscope, this atomic-sized color center maps ambient magnetic fields in a wide frequency range from DC up to several GHz, while retaining a high spatial resolution in the sub-nanometer range. We demonstrate imaging of single 10 nm sized magnetite nanoparticles using this spin noise detection technique. By fitting simulations (Ornstein-Uhlenbeck process) to the data, we are able to infer additional information on such a particle and its dynamics, like the attempt frequency and the anisotropy constant. This is of high interest to the proposed application of magnetite nanoparticles as an alternative MRI contrast agent or to the field of particle-aided tumor hyperthermia.

Turbine airfoil with ambient cooling system

Science.gov (United States)

Campbell, Jr, Christian X.; Marra, John J.; Marsh, Jan H.

2016-06-07

A turbine airfoil usable in a turbine engine and having at least one ambient air cooling system is disclosed. At least a portion of the cooling system may include one or more cooling channels configured to receive ambient air at about atmospheric pressure. The ambient air cooling system may have a tip static pressure to ambient pressure ratio of at least 0.5, and in at least one embodiment, may include a tip static pressure to ambient pressure ratio of between about 0.5 and about 3.0. The cooling system may also be configured such that an under root slot chamber in the root is large to minimize supply air velocity. One or more cooling channels of the ambient air cooling system may terminate at an outlet at the tip such that the outlet is aligned with inner surfaces forming the at least one cooling channel in the airfoil to facilitate high mass flow.

Definition of 1992 Technology Aircraft Noise Levels and the Methodology for Assessing Airplane Noise Impact of Component Noise Reduction Concepts

Science.gov (United States)

Kumasaka, Henry A.; Martinez, Michael M.; Weir, Donald S.

1996-01-01

This report describes the methodology for assessing the impact of component noise reduction on total airplane system noise. The methodology is intended to be applied to the results of individual study elements of the NASA-Advanced Subsonic Technology (AST) Noise Reduction Program, which will address the development of noise reduction concepts for specific components. Program progress will be assessed in terms of noise reduction achieved, relative to baseline levels representative of 1992 technology airplane/engine design and performance. In this report, the 1992 technology reference levels are defined for assessment models based on four airplane sizes - an average business jet and three commercial transports: a small twin, a medium sized twin, and a large quad. Study results indicate that component changes defined as program final goals for nacelle treatment and engine/airframe source noise reduction would achieve from 6-7 EPNdB reduction of total airplane noise at FAR 36 Stage 3 noise certification conditions for all of the airplane noise assessment models.

Rating environmental noise on the basis of noise maps

NARCIS (Netherlands)

Miedema, H.M.E.; Borst, H.C.

2006-01-01

A system that rates noise on the basis of noise maps has been developed which is based on empirical exposure-response relationships, so that effects in the community will be lower if the system gives a better rating. It is consistent with noise metrics and effect endpoint chosen in the EU, i.e., it

Yesterday's noise - today's signal

International Nuclear Information System (INIS)

Serdula, K.J.

1978-01-01

Plant performance can be improved by noise analysis. This paper describes noise characteristics, imposed noise and response functions, a case history of cost benefits derived from application of noise analysis techniques, areas for application of noise analysis techniques with special reference to the Gentilly-1 nuclear generating station, and the validity of noise measurement results. (E.C.B.)

Noise suppression in duct

International Nuclear Information System (INIS)

Ahmed, A.; Barfeh, M.A.G.

2001-01-01

In air-conditioning system the noise generated by supply fan is carried by conditioned air through the ductwork. The noise created in ductwork run may be transmission, regenerative and ductborne. Transmission noise is fan noise, regenerative noise is due to turbulence in flow and ductborne noise is the noise radiating from duct to surroundings. Some noise is attenuated in ducts also but if noise level is high then it needs to be attenuated. A simple mitre bend can attenuate-noise. This principle is extended to V and M-shape ducts with inside lining of fibreglass, which gave maximum attenuation of 77 dB and 62 dB respectively corresponding to 8 kHz frequency as compared to mitre, bend giving maximum 18 dB attenuation. Sound level meter measured sound levels with octave band filter and tests were conducted in anechoic room. A V-shape attenuator can be used at fan outlet and high frequency noise can be minimized greatly. (author)

Wide-band CMOS low-noise amplifier exploiting thermal noise canceling

OpenAIRE

Bruccoleri, F.; Klumperink, Eric A.M.; Nauta, Bram

2004-01-01

Known elementary wide-band amplifiers suffer from a fundamental tradeoff between noise figure (NF) and source impedance matching, which limits the NF to values typically above 3 dB. Global negative feedback can be used to break this tradeoff, however, at the price of potential instability. In contrast, this paper presents a feedforward noise-canceling technique, which allows for simultaneous noise and impedance matching, while canceling the noise and distortion contributions of the matching d...

Combat aircraft noise

Science.gov (United States)

Sgarbozza, M.; Depitre, A.

1992-04-01

A discussion of the characteristics and the noise levels of combat aircraft and of a transport aircraft in taking off and landing are presented. Some methods of noise reduction are discussed, including the following: operational anti-noise procedures; and concepts of future engines (silent post-combustion and variable cycle). Some measurement results concerning the noise generated in flight at great speeds and low altitude will also be examined. Finally, the protection of the environment of French air bases against noise will be described and the possibilities of regulation examined.

Ambient Air Quality Data Inventory

Data.gov (United States)

U.S. Environmental Protection Agency — The Office of Air and Radiation's (OAR) Ambient Air Quality Data (Current) contains ambient air pollution data collected by EPA, other federal agencies, as well as...

Listen to the noise: noise is beneficial for cognitive performance in ADHD.

Science.gov (United States)

Söderlund, Göran; Sikström, Sverker; Smart, Andrew

2007-08-01

Noise is typically conceived of as being detrimental to cognitive performance. However, given the mechanism of stochastic resonance, a certain amount of noise can benefit performance. We investigate cognitive performance in noisy environments in relation to a neurocomputational model of attention deficit hyperactivity disorder (ADHD) and dopamine. The Moderate Brain Arousal model (MBA; Sikström & Söderlund, 2007) suggests that dopamine levels modulate how much noise is required for optimal cognitive performance. We experimentally examine how ADHD and control children respond to different encoding conditions, providing different levels of environmental stimulation. Participants carried out self-performed mini tasks (SPT), as a high memory performance task, and a verbal task (VT), as a low memory task. These tasks were performed in the presence, or absence, of auditory white noise. Noise exerted a positive effect on cognitive performance for the ADHD group and deteriorated performance for the control group, indicating that ADHD subjects need more noise than controls for optimal cognitive performance. The positive effect of white noise is explained by the phenomenon of stochastic resonance (SR), i.e., the phenomenon that moderate noise facilitates cognitive performance. The MBA model suggests that noise in the environment, introduces internal noise into the neural system through the perceptual system. This noise induces SR in the neurotransmitter systems and makes this noise beneficial for cognitive performance. In particular, the peak of the SR curve depends on the dopamine level, so that participants with low dopamine levels (ADHD) require more noise for optimal cognitive performance compared to controls.

High-Speed Vessel Noises in West Hong Kong Waters and Their Contributions Relative to Indo-Pacific Humpback Dolphins (Sousa chinensis

Directory of Open Access Journals (Sweden)

Paul Q. Sims

2012-01-01

Full Text Available The waters of West Hong Kong are home to a population of Indo-Pacific humpback dolphins (Sousa chinensis that use a variety of sounds to communicate. This area is also dominated by intense vessel traffic that is believed to be behaviorally and acoustically disruptive to dolphins. While behavioral changes have been documented, acoustic disturbance has yet to be shown. We compared the relative sound contributions of various high-speed vessels to nearby ambient noise and dolphin social sounds. Ambient noise levels were also compared between areas of high and low traffic. We found large differences in sound pressure levels between high traffic and no traffic areas, suggesting that vessels are the main contributors to these discrepancies. Vessel sounds were well within the audible range of dolphins, with sounds from 315–45,000 Hz. Additionally, vessel sounds at distances ≥100 m exceeded those of dolphin sounds at closer distances. Our results reaffirm earlier studies that vessels have large sound contributions to dolphin habitats, and we suspect that they may be inducing masking effects of dolphin sounds at close distances. Further research on dolphin behavior and acoustics in relation to vessels is needed to clarify impacts.

Multispectral Analysis of Surface Wave (MASW) Analysis of Near-Surface Structure at Brady Hot Springs from Active Source and Ambient Noise Using a 8700-meter Distributed Acoustic Sensing (DAS) Array

Science.gov (United States)

Wang, H. F.; Lord, N. E.; Zeng, X.; Fratta, D.; Feigl, K. L.; Team, P.

2016-12-01

The Porotomo research team deployed 8700-meters of Distributed Acoustic Sensing (DAS) cable in a shallow trench on the surface and 400 meters down a borehole at Brady Hot Springs, Nevada in March 2016. The goal of the experiment was to detect changes in geophysical properties associated with hydrologic changes. The DAS cable occupied a natural laboratory of 1500-by-500-by-400-meters overlying a commercial, geothermal field operated by Ormat Technologies. The DAS cable was laid out in three parallel zig-zag lines with line segments approximately 120-meters in length. A large Vibroseis truck (T-Rex) provided the seismic source with a sweep frequency between 5 and 80 Hz over 20 seconds. Over the 15 days of the experiment, the Vibroseis truck re-occupied approximately 250 locations outside and within the array days while changes were made in water reinjection from the power plant into wells in the field. At each source location, one vertical and two orthogonal horizontal modes were excited. Dispersion curves were constructed using MASW and a Vibroseis source location approximately in line with each DAS cable segment or from ambient noise correlation functions. Representative fence diagrams of S-wave profiles were constructed by inverting the dispersion curves obtained for several different line segments.

An environment-adaptive management algorithm for hearing-support devices incorporating listening situation and noise type classifiers.

Science.gov (United States)

Yook, Sunhyun; Nam, Kyoung Won; Kim, Heepyung; Hong, Sung Hwa; Jang, Dong Pyo; Kim, In Young

2015-04-01

In order to provide more consistent sound intelligibility for the hearing-impaired person, regardless of environment, it is necessary to adjust the setting of the hearing-support (HS) device to accommodate various environmental circumstances. In this study, a fully automatic HS device management algorithm that can adapt to various environmental situations is proposed; it is composed of a listening-situation classifier, a noise-type classifier, an adaptive noise-reduction algorithm, and a management algorithm that can selectively turn on/off one or more of the three basic algorithms-beamforming, noise-reduction, and feedback cancellation-and can also adjust internal gains and parameters of the wide-dynamic-range compression (WDRC) and noise-reduction (NR) algorithms in accordance with variations in environmental situations. Experimental results demonstrated that the implemented algorithms can classify both listening situation and ambient noise type situations with high accuracies (92.8-96.4% and 90.9-99.4%, respectively), and the gains and parameters of the WDRC and NR algorithms were successfully adjusted according to variations in environmental situation. The average values of signal-to-noise ratio (SNR), frequency-weighted segmental SNR, Perceptual Evaluation of Speech Quality, and mean opinion test scores of 10 normal-hearing volunteers of the adaptive multiband spectral subtraction (MBSS) algorithm were improved by 1.74 dB, 2.11 dB, 0.49, and 0.68, respectively, compared to the conventional fixed-parameter MBSS algorithm. These results indicate that the proposed environment-adaptive management algorithm can be applied to HS devices to improve sound intelligibility for hearing-impaired individuals in various acoustic environments. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Prewhitening for Rank-Deficient Noise in Subspace Methods for Noise Reduction

DEFF Research Database (Denmark)

Hansen, Per Christian; Jensen, Søren Holdt

2005-01-01

A fundamental issue in connection with subspace methods for noise reduction is that the covariance matrix for the noise is required to have full rank, in order for the prewhitening step to be defined. However, there are important cases where this requirement is not fulfilled, e.g., when the noise...... has narrow-band characteristics, or in the case of tonal noise. We extend the concept of prewhitening to include the case when the noise covariance matrix is rank deficient, using a weighted pseudoinverse and the quotient SVD, and we show how to formulate a general rank-reduction algorithm that works...... also for rank deficient noise. We also demonstrate how to formulate this algorithm by means of a quotient ULV decomposition, which allows for faster computation and updating. Finally we apply our algorithm to a problem involving a speech signal contaminated by narrow-band noise....

BWR noise spectra and application of noise analysis to FBR

International Nuclear Information System (INIS)

Nomura, T.

1975-01-01

Work related to noise analysis, in Tokyo Shibaura Electric Co. Ltd. (Toshiba) and Nippon Atomic Industry Group Co. Ltd. (NAIG) for the past several years is reviewed. After considering the Japan-United States Seminar on Reactor Noise Analysis in 1968, other subjects discussed were boiling water reactor noise analysis and work in relation to FBR. Parts of these are related to each other. For example, boiling detection and temperature fluctuations are problems pertinent to both fields. As the main problems in zero-power-reactor noise are now basically understood, only a brief description of the experiments involving the advanced two detector method is made. Focus is rather placed on the area of power plant noise. (author)

La Educación Ambiental una herramienta clave de la Gestión Ambiental

Directory of Open Access Journals (Sweden)

María josé Esteves Ivanissevich

2013-06-01

Full Text Available Entendemos que el objeto de la educación ambiental no es el ambiente como tal, sino nuestra relación con él; la multiplicidad y diversidad de objetivos y la necesidad de anclar la intervención en cada contexto específico, hace de ésta una tarea inmensa y compleja. La provincia del Chubut registra desde el año 1999 un historial importante. Éste trabajo, toma lo realizado en la temática de eliminación de bolsas de polietileno en los espacios públicos, de forma interinstitucional y en ámbitos educativo formal y no formal. Con la hipótesis de que la educación ambiental constituye un instrumento de política ambiental preventivo atendiendo los problemas que afecten o pudieran afectar al ambiente; nos planteamos como objetivos: construir una ciudadanía ambientalmente responsable; Impulsar la formación y capacitación de docentes y actores sociales con una mirada ambiental; Contribuir a la conservación ambiental disponiendo de las nuevas tecnologías. La metodología se sustenta en una concepción que hace eje en el aumento de la participación de la sociedad. Desde el ámbito formal se trabajó durante el 2007-2011 con capacitaciones presenciales y a distancia, para docentes de nivel inicial y primario (434 capacitados, en forma conjunta con el Ministerio de Educación. El equipo de trabajo consta de cuatro profesionales del Ministerio de Ambiente y la colaboración de especialistas según el lugar y la temática. En el ámbito no formal se realizaron charlas y talleres con la comunidad (5826 capacitados; comunicación extrainstitucional por medios masivos de comunicación; campañas ambientales, trabajando en forma conjunta con organismos municipales, provinciales, no gubernamentales y privados. Se cubrieron 28 localidades en todo el territorio provincial. Se abarcó un gran número de docentes, quedando el trabajo con directores y supervisores, para pensar en la inclusión de las temáticas como los residuos sólidos urbanos, en el

Damping Identification of Bridges Under Nonstationary Ambient Vibration

Directory of Open Access Journals (Sweden)

Sunjoong Kim

2017-12-01

Full Text Available This research focuses on identifying the damping ratio of bridges using nonstationary ambient vibration data. The damping ratios of bridges in service have generally been identified using operational modal analysis (OMA based on a stationary white noise assumption for input signals. However, most bridges are generally subjected to nonstationary excitations while in service, and this violation of the basic assumption can lead to uncertainties in damping identification. To deal with nonstationarity, an amplitude-modulating function was calculated from measured responses to eliminate global trends caused by nonstationary input. A natural excitation technique (NExT-eigensystem realization algorithm (ERA was applied to estimate the damping ratio for a stationarized process. To improve the accuracy of OMA-based damping estimates, a comparative analysis was performed between an extracted stationary process and nonstationary data to assess the effect of eliminating nonstationarity. The mean value and standard deviation of the damping ratio for the first vertical mode decreased after signal stationarization. Keywords: Damping, Operational modal analysis, Traffic-induced vibration, Nonstationary, Signal stationarization, Amplitude-modulating, Bridge, Cable-stayed, Suspension

Noise Gating Solar Images

Science.gov (United States)

DeForest, Craig; Seaton, Daniel B.; Darnell, John A.

2017-08-01

I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO

Evaluación Ambiental Estratégica y Auditoría Contable Ambiental como Instrumentos para la Optimización de la Política Pública Ambiental en el Brasil

Directory of Open Access Journals (Sweden)

Gardênia Maria Braga de Carvalho

2014-01-01

Full Text Available La política ambiental es un conjunto de directrices, objetivos e instrumentos de acción que el poder público utiliza para producir efectos deseables sobre el medio ambiente. Algunos de esos instrumentos aunque no están institucionalizados, como la Evaluación Ambiental Estratégica (AAE, que objetiva desarrollar un estudio macro de los impactos causados al medio ambiente y a la comunidad; y la Auditoría Contable Ambiental (ACA, que consiste en la confrontación de las informaciones de los informes ambientales y contables. Así, se cuestiona: a ¿qué problemas generados por la ausencia de la AAE y de la ACA en la política ambiental brasileira? b ¿cómo la inserción de la AAE y de la ACA contribuiría para la solución de los problemas específicos detectados? Este artículo tiene como objetivo demostrar que existe una laguna en la política ambiental por desconsideración de esos instrumentos. El referencial teórico fue construido teniendo como base la contabilidad ambiental, auditoría ambiental y política pública. Se utilizó como método el análisis descriptivo en relación a sus objetivos, siendo realizada una pesquisa bibliográfica y exploratoria sobre los temas: políticas públicas, AAE y ACA. Se concluye que es necesaria la institucionalización de la AAE y de la ACA, en la fase inicial y final, respectivamente, del proceso de instalación y acompañamiento de emprendimientos impactantes al medio ambiente, pues el hecho de no ser compulsorios, revelaron una laguna en la política ambiental, tornándola frágil.

Microseismic noise in the Saint Peter and Saint Paul Archipelago, equatorial Atlantic

Science.gov (United States)

de Queiroz, Daniel É.; do Nascimento, Aderson F.; Schimmel, Martin

2017-12-01

Microseismic noise, also known as ambient seismic noise, are continuous vibrations mostly composed of Rayleigh waves pervasively recorded in the mili Hertz to 1 Hz frequency range. Their precise source mechanisms are under investigations and related to atmospheric perturbations and ocean gravity waves. Our purpose is to show the behavior of the microseismic noise recorded in the Saint Peter and Saint Paul Archipelago (SPSPA) with respect to wind intensity and ocean waves height in this region, between the North and South Atlantic Ocean. We have recorded both primary microseisms (PM) 0.04-0.12 Hz and the secondary microseisms (SM) 0.12-0.4 Hz during almost four years (2012-2015) and we used frequency, temporal, spatial and statistical correlation analysis to do qualitative and quantitative analysis with respect to wind speed intensity and significant wave height for the same periods. The results indicate a good correlation between the PM and the SM noise in the region particularly during the winter in the Northern Hemisphere and a poor correlation during the summer. We have also shown that probably most of the PM are generated in the SPSPA itself. We note that the intensity of SM recorded in SPSPA appears to have a seasonal behavior with the summer and winter in the Northern Hemisphere, and seems to influence the correlation between the PM and the SM, suggesting that the sources of the PM and the SM are not related to the same atmospheric event and from different places. PM generation would occur near the SPSPA whilst the SM would have distant sources towards the North Atlantic.

Noise sensitivity and reactions to noise and other environmental conditions

NARCIS (Netherlands)

Miedema, H.M.E.; Vos, H.

2003-01-01

This article integrates findings from the literature and new results regarding noise sensitivity. The new results are based on analyses of 28 combined datasets (N=23 038), and separate analyses of a large aircraft noise study (N=10939). Three topics regarding noise sensitivity are discussed, namely,

Adaptive noise cancellation

International Nuclear Information System (INIS)

Akram, N.

1999-01-01

In this report we describe the concept of adaptive noise canceling, an alternative method of estimating signals corrupted by additive noise of interference. The method uses 'primary' input containing the corrupted signal and a 'reference' input containing noise correlated in some unknown way with the primary noise, the reference input is adaptively filtered and subtracted from the primary input to obtain the signal estimate. Adaptive filtering before subtraction allows the treatment of inputs that are deterministic or stochastic, stationary or time variable. When the reference input is free of signal and certain other conditions are met then noise in the primary input can be essentially eliminated without signal distortion. It is further shown that the adaptive filter also acts as notch filter. Simulated results illustrate the usefulness of the adaptive noise canceling technique. (author)

Critical Low-Noise Technologies Being Developed for Engine Noise Reduction Systems Subproject

Science.gov (United States)

Grady, Joseph E.; Civinskas, Kestutis C.

2004-01-01

NASA's previous Advanced Subsonic Technology (AST) Noise Reduction Program delivered the initial technologies for meeting a 10-year goal of a 10-dB reduction in total aircraft system noise. Technology Readiness Levels achieved for the engine-noise-reduction technologies ranged from 4 (rig scale) to 6 (engine demonstration). The current Quiet Aircraft Technology (QAT) project is building on those AST accomplishments to achieve the additional noise reduction needed to meet the Aerospace Technology Enterprise's 10-year goal, again validated through a combination of laboratory rig and engine demonstration tests. In order to meet the Aerospace Technology Enterprise goal for future aircraft of a 50- reduction in the perceived noise level, reductions of 4 dB are needed in both fan and jet noise. The primary objectives of the Engine Noise Reduction Systems (ENRS) subproject are, therefore, to develop technologies to reduce both fan and jet noise by 4 dB, to demonstrate these technologies in engine tests, and to develop and experimentally validate Computational Aero Acoustics (CAA) computer codes that will improve our ability to predict engine noise.

Phenomenon of entropic stochastic resonance with asymmetric dichotomous noise and white noise

International Nuclear Information System (INIS)

Guo, Feng; Li, Shao-Fu; Cheng, Xiao-Feng

2012-01-01

The entropic stochastic resonance (ESR) in a confined system subject to asymmetric dichotomous noise, white noise, and a periodic square-wave signal is investigated. Under the adiabatic approximation condition, by use of the properties of the dichotomous noise, we obtain the expression of the output signal-to-noise ratio (SNR) based on two-state theory. The SNR is shown to be a nonmonotonic function of the strength and asymmetry of the dichotomous noise, the intensity of the white noise, and the amplitude of the square-wave signal. The SNR varies non-monotonically with increases in the parameters of the confined structure. The influence of the correlation rate of the dichotomous noise and the frequency of the external constant force on the SNR is also discussed.

When noise is beneficial for sensory encoding: Noise adaptation can improve face processing.

Science.gov (United States)

Menzel, Claudia; Hayn-Leichsenring, Gregor U; Redies, Christoph; Németh, Kornél; Kovács, Gyula

2017-10-01

The presence of noise usually impairs the processing of a stimulus. Here, we studied the effects of noise on face processing and show, for the first time, that adaptation to noise patterns has beneficial effects on face perception. We used noiseless faces that were either surrounded by random noise or presented on a uniform background as stimuli. In addition, the faces were either preceded by noise adaptors or not. Moreover, we varied the statistics of the noise so that its spectral slope either matched that of the faces or it was steeper or shallower. Results of parallel ERP recordings showed that the background noise reduces the amplitude of the face-evoked N170, indicating less intensive face processing. Adaptation to a noise pattern, however, led to reduced P1 and enhanced N170 amplitudes as well as to a better behavioral performance in two of the three noise conditions. This effect was also augmented by the presence of background noise around the target stimuli. Additionally, the spectral slope of the noise pattern affected the size of the P1, N170 and P2 amplitudes. We reason that the observed effects are due to the selective adaptation of noise-sensitive neurons present in the face-processing cortical areas, which may enhance the signal-to-noise-ratio. Copyright © 2017 Elsevier Inc. All rights reserved.

Croatian Experience in Road Traffic Noise Management - Concrete Noise Barriers

Directory of Open Access Journals (Sweden)

Ahac Saša

2014-07-01

Full Text Available The paper gives an overview of concrete noise barrier application in several EU countries and in Croatia. It describes a process of introducing different noise protection solutions on Croatian market in the phase of intensive motorway construction in recent years. Namely, an extensive motorway network has been constructed in Croatia in the last 10 years. Following the process of motorway construction, noise protection walls have also been erected. Usage of different building materials and installation processes as well as variations in building expenditures has led to a comparative analysis of several types of noise protection solutions (expanded clay, wood fibre including a new eco-innovative product RUCONBAR, which incorporates rubber granules from recycled waste tyres to form a porous noise absorptive layer.

Intensidade de ruído em hospital de 222 leitos na 18ª Regional de Saúde - PR Noise level in a 222 bed hospital in the 18th health region - PR

Directory of Open Access Journals (Sweden)

Marcelo Henrique Otenio

2007-04-01

Full Text Available A poluição sonora ambiental torna-se hoje onipresente e beira o intolerável. Nos hospitais, os avanços tecnológicos trazem, como conseqüência, níveis de ruído potencialmente danosos. Muito do ruído no hospital provém mais de dentro, do que de fora desse ambiente, sendo as principais causas de ruído em Unidade de Terapia Intensiva, por exemplo, os equipamentos e a conversação entre a equipe hospitalar. O objetivo deste trabalho foi avaliar o nível de ruído nos diversos ambientes hospitalares, em Hospital de 222 leitos na 18ª RS de Saúde - PR. MATERIAIS E MÉTODOS: Conduziu-se, em março de 2005 no período de 24 horas, em dez setores. Forma de Estudo: Aferição do nível de ruído ambiental utilizando um Decibelímetro modelo 1350. RESULTADOS: O nível de ruído encontrado em nosso estudo apresentou média total de 63,7 dB(A, que excede os valores máximos permitidos de 45 dB recomendados pela Associação Brasileira de Normas Técnicas (1987. CONCLUSÃO: Nos setores analisados, o nível de ruído encontrado neste está consideravelmente acima do recomendado. A equipe hospitalar deve estar consciente do ruído e dos efeitos deste, para que possa atuar de maneira mais efetiva na redução da poluição sonora, beneficiando assim a função laborativa dos profissionais e recuperação dos pacientes.Environment noise pollution is common place today, at intolerable levels. In hospitals, technological developments have, as a consequence, potentially harmful noise levels. Much of the hospital noise comes from inside, rather than outside, and the major source of such noise is the Intensive Care Unit, for example equipment and hospital staff talk. Our goal with the present study was to investigate the noise level present in the different hospital environments, within a 222 bed hospital located at the 18th health zone, PR. MATERIALS AND METHODS: The study was carried out in March, 2005, during a period of 24 hours, in tem different

Elimination of noise peak for signal processing in Johnson noise thermometry development

International Nuclear Information System (INIS)

Hwang, I. G.; Moon, B. S.; Jeong, J. E.; Jeo, Y. H.; Kisner, Roger A.

2003-01-01

The internal and external noise is the most considering obstacle in development of Johnson Noise Thermometry system. This paper addresses an external noise elimination issue of the Johnson Noise Thermometry system which is underway of development in collaboration between KAERI and ORNL. Although internal random noise is canceled by Cross Power Spectral Density function, a continuous wave penetrating into the electronic circuit is eliminated by the difference of peaks between Johnson signal and external noise. The elimination logic using standard deviation of CPSD and energy leakage problem in discrete CPSD function are discussed in this paper

Effects of road traffic background noise on judgments of individual airplane noises. Ph.D. Thesis

Science.gov (United States)

Powell, C. A.

1979-01-01

Two laboratory experiments were conducted to investigate the effects of road-traffic background noise on judgments of individual airplane flyover noises. In the first experiment, 27 subjects judged a set of 16 airplane flyover noises in the presence of traffic-noise sessions of 30-min duration consisting of the combinations of 3 traffic-noise types and 3 noise levels. In the second experiment, 24 subjects judged the same airplane flyover noises in the presence of traffic-noise sessions of 10-min duration consisting of the combinations of 2 traffic-noise types and 4 noise levels. In both experiments the airplane noises were judged less annoying in the presence of high traffic-noise levels than in the presence of low traffic-noise levels.

Low voltage excess noise and shot noise in YBCO bicrystal junctions

DEFF Research Database (Denmark)

Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.

2002-01-01

The spectral density of background noise emitted by symmetric bicrystal YBaCuO Josephson junctions on sapphire substrates have been measured by a low noise cooled HEMT amplifier for bias voltages up to V approximate to 50 mV. At relatively low voltages V noise rise has been...... registered. At large bias voltages V > 30 mV a clear dependence of noise power. exactly coinciding to the asymptote of the Schottky shot noise function, has been observed for the first time. Experimental results are discussed in terms of multiple Andreev reflections which may take place in d...

Imaging of Upper-Mantle Upwelling Beneath the Salton Trough, Southern California, by Joint Inversion of Ambient Noise Dispersion Curves and Receiver Functions

Science.gov (United States)

Klemperer, S. L.; Barak, S.

2016-12-01

We present a new 2D shear-wave velocity model of the crust and upper-mantle across the Salton Trough, southern California, obtained by jointly inverting our new dataset of receiver functions and our previously published Rayleigh-wave group-velocity model (Barak et al., G-cubed, 2015), obtained from ambient-noise tomography. Our results show an upper-mantle low-velocity zone (LVZ) with Vs ≤4.2 km/s extending from the Elsinore Fault to the Sand Hills Fault, that together bracket the full width of major San Andreas dextral motion since its inception 6 Ma b.p., and underlying the full width of low topography of the Imperial Valley and Salton Trough. The lateral extent of the LVZ is coincident with the lateral extent of an upper-mantle anisotropic region interpreted as a zone of SAF-parallel melt pockets (Barak & Klemperer, Geology, 2016). The shallowest part of the LVZ is 40 km depth, coincident with S-receiver function images. The western part of the LVZ, between the Elsinore and San Jacinto faults (the region of greatest modern dextral slip), appears to continue to significantly greater depth; but a puzzling feature of our preliminary models is that the eastern part of the LVZ, from the San Jacinto Fault to the Sand Hills Fault, appears to be underlain by more-normalvelocity upper mantle (Vs ≥ 4.5 km/s) below 75 km depth. We compare our model to the current SCEC community models CVM-H and CVM-S, and to P-wave velocity models obtained by the active-source Salton Sea Imaging Project (SSIP). The hypothesized lower-crustal low-velocity zone beneath the Salton Trough in our previous model (Barak et al., G-cubed, 2015), there interpreted as a region of partial melt, is not supported by our new modeling. Melt may be largely absent from the lower crust of the Salton trough; but appears required in the upper mantle at depths as shallow as 40 km.

Indirect Combustion Noise: Noise Generation by Accelerated Vorticity in a Nozzle Flow

Directory of Open Access Journals (Sweden)

Nancy Kings

2010-09-01

Full Text Available The noise generation by accelerated vorticity waves in a nozzle flow was investigated in a model experiment. This noise generation mechanism belongs, besides entropy noise, to the indirect combustion noise phenomena. Vorticity as well as entropy fluctuations, originating from the highly turbulent combustion zone, are convected with the flow and produce noise during their acceleration in the outlet nozzle of the combustion chamber. In the model experiment, noise generation of accelerated vorticity fluctuations was achieved. The vorticity fluctuations in the tube flow were produced by injecting temporally additional air into the mean flow. As the next step, a parametric study was conducted to determine the major dependencies of the so called vortex noise. A quadratic dependency of the vortex noise on the injected air amount was found. In order to visualise and classify the artificially generated vorticity structures, planar velocity measurements have been conducted applying Particle Image Velocimetry (PIV.

Development of Active Noise Control System for Quieting Transformer Noise

Energy Technology Data Exchange (ETDEWEB)

Lee, Bok Kyu; Song, Seik Young; Choi, Huo Yul [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Yun, Dae Hea; Lee, Hyuk Jae [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)

1997-12-31

The passive noise control technique made use of sound-absorbing or soundproofing materials, so it required a large area and high cost for installation and had a drawback of poor performance at low frequency. Compared to this, the Active Noise Control attenuates noise sound pressure by using secondary source which has same performance ay low-frequency. Furthermore, it is able to save space and expenses. - research on adaptive algorithms - evaluation of global attenuation of the control - computer simulation - real-time Active Noise Control System Hardware Implementation - ANC system setting in the noisy area.