WorldWideScience

Sample records for ambient noise

  1. Ambient noise near the sea-route

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Ambient noise data measured in an experiment conducted in shallow water near a sea-route were analyzed. It was observed that, at low frequency, the horizontal correlation has an obvious difference from that predicted by the classical ambient noise model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different times verify that the proposed model can be used to forecast the ambient noise field in shallow water near the sea-route.

  2. Ambient noise near the sea-route

    Institute of Scientific and Technical Information of China (English)

    HE Li; LI ZhengLin; PENG ZhaoHui

    2009-01-01

    Ambient noise data measured in an experiment conducted in shallow water near a sea-route were analyzed. It was observed that, at low frequency, the horizontal correlation has an obvious difference from that predicted by the classical ambient noise model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different times verify that the proposed model can be used to forecast the ambient noise field in shal-low water near the sea-route.

  3. Ocean Ambient Noise Measurement and Theory

    CERN Document Server

    Carey, William M

    2011-01-01

    This book develops the theory of ocean ambient noise mechanisms and measurements, and also describes general noise characteristics and computational methods.  It concisely summarizes the vast ambient noise literature using theory combined with key representative results.  The air-sea boundary interaction zone is described in terms of non-dimensional variables requisite for future experiments.  Noise field coherency, rare directional measurements, and unique basin scale computations and methods are presented.  The use of satellite measurements in these basin scale models is demonstrated.  Finally, this book provides a series of appendices giving in-depth mathematical treatments.  With its complete and careful discussions of both theory and experimental results, this book will be of the greatest interest to graduate students and active researchers working in fields related to ambient noise in the ocean.

  4. Ambient Noise Tomography of the British Isles

    Science.gov (United States)

    Nicolson, H. J.; Curtis, A.; Baptie, B.

    2009-12-01

    In recent years, surface wave tomography using empirical Green’s functions computed via the ambient noise interferometry method has become an established approach to lithospheric imaging problems. To date, ambient noise tomography has been successfully applied to seismometer arrays in the United States, Australia, Iceland, China, South Africa, Europe and the Tibetan Plateau. The basis of the ambient seismic interferometry method is that, by cross-correlating noise data between two seismic stations and stacking over a long enough time period, one can approximate the Green’s Function that would have been recorded at one of the stations if the other had actually been a source. Consequently, one of the main advantages of ambient noise interferometry is that traditional seismic sources such as earthquakes or ballistics are not required; therefore it is ideal for application to seismically quiescent areas such as the British Isles. The British Isles are an archipelago located adjacent to the Eurasian continental shelf in a typically intra-plate setting, formed by a complex amalgamation of several terranes. These range from Laurentian north of the Highland Boundary fault to Avalonian south of the Iapetus Suture and evidence of the regions turbulent geological past can be inferred from its lithospheric structure. Previous studies of the structure of the British Isles considered relatively few seismic stations and/or were limited to using offshore shots, quarry blasts or teleseismic earthquakes as seismic energy sources. We have applied the ambient noise tomography method to noise data recorded on approximately 100 broadband and short period seismometers, including many new stations, in the British Isles and mainland Europe. This dense coverage of the British Isles allows us to image the crust and upper mantle velocity structure with a horizontal resolution in the region of 100km across the North Sea and 30km in the mainland United Kingdom. Here we present the first

  5. Broadband Finite Frequency Ambient Noise Tomography

    Science.gov (United States)

    Zhao, K.; Yang, Y.; Luo, Y.; Xie, J.

    2015-12-01

    Ambient noise tomography (ANT) has become a popular method to study the crustal and uppermost mantle structure of the earth in recent years due to its exclusive capability to extract short-period surface wave signals. Most of ANT are based on ray theory that assumes interstation surface waves from ambient noise are mainly sensitive to a narrow zone alone the ray path from one station to the other. Recently, many studies have demonstrated that long-period Rayleigh wave signal with high SNR can be obtained from cross-correlation of ambient noise data and could be used to do long period surface ware tomography. In order to obtain accurate phase velocity maps using long period surface waves from ambient noise, frequency effects must be considered in tomography. In this study, we investigate the feasibility of finite frequency ANT by calculating 2-D phase sensitivity kernel based on Born approximation. In calculating 2D sensitivity kernels for empirical Green's functions extracted from cross-correlations between a pair of stations, one station is regarded as receiver and the other as virtual source. Based on the 2D finite frequency sensitivity kennels, we develop a finite frequency ambient noise tomography method to construct Rayleigh wave phase velocity maps. To demonstrate the feasibility of our developed method, we apply the method to empirical Green's functions extracted from cross-correlations of USArray noise data to construct phase velocity maps at 20-150 sec periods. Our resulting phase velocity maps are very similar to earthquake-based phase velocity maps with almost zero means and 20-30 m/s stand deviations of differences. Major tectonic features in USA are well revealed in our phase velocity maps.

  6. 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.

  7. Horizontal Correlation of Ambient Noise near a Sea Route

    Institute of Scientific and Technical Information of China (English)

    HE Li; LI Zheng-Lin; ZHANG Ren-He; PENG Zhao-Hui

    2008-01-01

    Ambient noise data measured in an experiment conducted near the sea route are analysed.It is found that at low frequency,the measured horizontal correlation coeffients at different separations oscillate much larger than that predicted by the classical ambient noise model.The theoretical analyses show that the observed phenomenon is mainly caused by windy noise together with the discrete shipping noise nearby.An ambient noise model is proposed to include the effects caused by both the noise sources and can be used to forecast the ambient noise field neara sea route.

  8. Ambient noise spectral properties in the north area of Xisha

    Institute of Scientific and Technical Information of China (English)

    DA Lianglong; WANG Chao; HAN Mei; ZHANG Lin

    2014-01-01

    Ambient noise is very important in the prediction system of a sonar performance, because it determines the detection ranges always in a passive sonar and usually in an active sonar. In the uncertainty issue for the so-nar performance, it is necessary to know this factor’s statistical characteristics that are only obtained by data processing from the underwater ambient noise measurements. Broad-band ambient noise signals from 16 hydrophones were amplified and recorded for 2 min every 1 h. The results show that the ambient noise is essentially depth independent. The cross correlation of the ambient noise levels (1, 6 and 12 h average) with a wind speed is presented. It was found that the correlation is excellent on the upper frequency band and the noise levels correlate better with high wind speed than with low wind speed.

  9. Cross-correlations of ambient noise recorded by accelerometers.

    Science.gov (United States)

    Rábade García, S. E.; Ramirez-Guzman, L.

    2014-12-01

    We investigate the ambient noise cross-correlations obtained by using properly corrected accelerometric recordings, and determine velocity structure in central Mexico based on a dispersion analysis. The data used comprise ten months of continuous recordings - from April 2013 to January 2014 - of ambient seismic noise at stations operated by the National Seismological Service of Mexico and the Engineering Strong Ground Motion Network of the National Autonomous University of Mexico (UNAM). The vertical component of ambient noise was base-line corrected, filtered, and properly integrated before extracting Green's functions (GF), which were compared successfully against GF obtained using recordings from broadband velocity sensors. In order to obtain dispersion curves, we estimated group and phase velocities applying the FTAN analysis technique and obtained s-wave velocity profiles at selected regions. We conclude and highlight that the use of widely deployed accelerographs to conduct regional studies using ambient noise tomography is feasible

  10. Geoacoustic inversion of ambient noise: A simple method.

    NARCIS (Netherlands)

    Harrison, C.H.; Simons, D.G.

    2002-01-01

    The vertical directionality of ambient noise is strongly influenced by seabed reflections. Therefore, potentially, geoacoustic parameters can be inferred by inversion of the noise. In this approach, using vertical array measurements, the reflection loss is found directly by comparing the upward- wit

  11. Ambient noise levels and detection threshold in Norway

    Science.gov (United States)

    Demuth, Andrea; Ottemöller, Lars; Keers, Henk

    2016-07-01

    Ambient seismic noise is caused by a number of sources in specific frequency bands. The quantification of ambient noise makes it possible to evaluate station and network performance. We evaluate noise levels in Norway from the 2013 data set of the Norwegian National Seismic Network as well as two temporary deployments. Apart from the station performance, we studied the geographical and temporal variations, and developed a local noise model for Norway. The microseism peaks related to the ocean are significant in Norway. We, therefore, investigated the relationship between oceanic weather conditions and noise levels. We find a correlation of low-frequency noise (0.125-0.25 Hz) with wave heights up to 900 km offshore. High (2-10 Hz) and intermediate (0.5-5 Hz) frequency noise correlates only up to 450 km offshore with wave heights. From a geographic perspective, stations in southern Norway show lower noise levels for low frequencies due to a larger distance to the dominant noise sources in the North Atlantic. Finally, we studied the influence of high-frequency noise levels on earthquake detectability and found that a noise level increase of 10 dB decreases the detectability by 0.5 magnitude units. This method provides a practical way to consider noise variations in detection maps.

  12. Masking of Wind Turbine Noise: Influence of wind turbulence on ambient noise fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Fegeant, Olivier

    2002-07-01

    In the issue of noise annoyance generated by wind turbines, masking by ambient noise is of great importance. At wind turbine sites, the main source of ambient noise arises from the wind blowing on the vegetation. However, natural wind can barely be described as a steady flow and 'lulls' and 'gusts' are words used to describe its unsteady component. This latter, also called wind turbulence, may affect the masking effect, as the wind turbine may become audible during short laps of time of low wind speed, that is of low ambient noise. The aim of the present report is to study the influence of wind turbulence on ambient noise fluctuations. It is shown that these latter are governed not only by the turbulence intensity, but also by its temporal and spatial structure. This report provides some elements of atmospheric turbulence as well as techniques for the simulation of turbulent wind fields. Simulation results are given that illustrate how the standard deviation of the vegetation noise can vary as function of the canopy size and turbulence spatial patterns. Finally, ambient noise fluctuations and their statistical descriptions are also discussed, based on both theoretical considerations and empirical results.

  13. Robust seismic velocity change estimation using ambient noise recordings

    CERN Document Server

    Daskalakis, E; Garnier, J; Melis, N S; Papanicolaou, G; Tsogka, C

    2016-01-01

    We consider the problem of seismic velocity change estimation using ambient noise recordings. Motivated by [23] we study how the velocity change estimation is affected by seasonal fluctuations in the noise sources. More precisely, we consider a numerical model and introduce spatio-temporal seasonal fluctuations in the noise sources. We show that indeed, as pointed out in [23], the stretching method is affected by these fluctuations and produces misleading apparent velocity variations which reduce dramatically the signal to noise ratio of the method. We also show that these apparent velocity variations can be eliminated by an adequate normalization of the cross-correlation functions. Theoretically we expect our approach to work as long as the seasonal fluctuations in the noise sources are uniform, an assumption which holds for closely located seismic stations. We illustrate with numerical simulations and real measurements that the proposed normalization significantly improves the accuracy of the velocity chang...

  14. When ambient noise impairs parent-offspring communication.

    Science.gov (United States)

    Lucass, Carsten; Eens, Marcel; Müller, Wendt

    2016-05-01

    Ambient noise has increased in extent, duration and intensity with significant implications for species' lives. Birds especially, because they heavily rely on vocal communication, are highly sensitive towards noise pollution. Noise can impair the quality of a territory or hamper the transmission of vocal signals such as song. The latter has significant fitness consequences as it may erode partner preferences in the context of mate choice. Additional fitness costs may arise if noise masks communication between soliciting offspring and providing parents during the period of parental care. Here, we experimentally manipulated the acoustic environment of blue tit (Cyanistes caeruleus) families within their nest boxes with playbacks of previously recorded highway noise and investigated the consequences on parent-offspring communication. We hypothesized that noise interferes with the acoustic cues of parental arrival and vocal components of offspring begging. As such we expected an increase in the frequency of missed detections, when nestlings fail to respond to the returning parent, and a decrease in parental provisioning rates. Parents significantly reduced their rate of provisioning in noisy conditions compared to a control treatment. This reduction is likely to be the consequence of a parental misinterpretation of the offspring hunger level, as we found that nestlings fail to respond to the returning parent more frequently in the presence of noise. Noise also potentially masks vocal begging components, again contributing to parental underestimation of offspring requirements. Either way, it appears that noise impaired parent-offspring communication is likely to reduce reproductive success. PMID:26986090

  15. Shear velocity of the Rotokawa geothermal field using ambient noise

    Science.gov (United States)

    Civilini, F.; Savage, M. K.; Townend, J.

    2014-12-01

    Ambient noise correlation is an increasingly popular seismological technique that uses the ambient seismic noise recorded at two stations to construct an empirical Green's function. Applications of this technique include determining shear velocity structure and attenuation. An advantage of ambient noise is that it does not rely on external sources of seismic energy such as local or teleseismic earthquakes. This method has been used in the geothermal industry to determine the depths at which magmatic processes occur, to distinguish between production and non-production areas, and to observe seismic velocity perturbations associated with fluid extraction. We will present a velocity model for the Rotokawa geothermal field near Taupo, New Zealand, produced from ambient noise cross correlations. Production at Rotokawa is based on the "Rotokawa A" combined cycle power station established in 1997 and the "Nga Awa Purua" triple flash power plant established in 2010. Rotokawa Joint Venture, a partnership between Mighty River Power and Tauhara North No. 2 Trust currently operates 174 MW of generation at Rotokawa. An array of short period seismometers was installed in 2008 and occupies an area of roughly 5 square kilometers around the site. Although both cultural and natural noise sources are recorded at the stations, the instrument separation distance provides a unique challenge for analyzing cross correlations produced by both signal types. The inter-station spacing is on the order of a few kilometers, so waves from cultural sources generally are not coherent from one station to the other, while the wavelength produced by natural noise is greater than the station separation. Velocity models produced from these two source types will be compared to known geological models of the site. Depending on the amount of data needed to adequately construct cross-correlations, a time-dependent model of velocity will be established and compared with geothermal production processes.

  16. A high-resolution ambient seismic noise model for Europe

    Science.gov (United States)

    Kraft, Toni

    2014-05-01

    In the past several years, geological energy technologies receive growing attention and have been initiated in or close to urban areas. Some of these technologies involve injecting fluids into the subsurface (e.g., oil and gas development, waste disposal, and geothermal energy development) and have been found or suspected to cause small to moderate sized earthquakes. These earthquakes, which may have gone unnoticed in the past when they occurred in remote sparsely populated areas, are now posing a considerable risk for the public acceptance of these technologies in urban areas. The permanent termination of the EGS project in Basel, Switzerland after a number of induced ML~3 (minor) earthquakes in 2006 is one prominent example. It is therefore essential to the future development and success of these geological energy technologies to develop strategies for managing induced seismicity and keeping the size of induced earthquake at a level that is acceptable to all stakeholders. Most guidelines and recommendations on induced seismicity published since the 1970ies conclude that an indispensable component of such a strategy is the establishment of seismic monitoring in an early stage of a project. This is because an appropriate seismic monitoring is the only way to detect and locate induced microearthquakes with sufficient certainty to develop an understanding of the seismic and geomechanical response of the reservoir to the geotechnical operation. In addition, seismic monitoring lays the foundation for the establishment of advanced traffic light systems and is therefore an important confidence building measure towards the local population and authorities. Due to this development an increasing number of seismic monitoring networks are being installed in densely populated areas with strongly heterogeneous, and unfavorable ambient noise conditions. This poses a major challenge on the network design process, which aims to find the sensor geometry that optimizes the

  17. Analysis of acoustic ambient noise in Monterey Bay, California.

    OpenAIRE

    Elles, Christopher Jacob.

    1982-01-01

    Approved for public release; distribution is unlimited Magnetic tape recordings, made in 1980 and 1981 by previous investigators using sonobuoys, of acoustic ambient noise in the south-eastern parts of Monterey Bay for various stations under various surf conditions, were analyzed. A computer program was developed and used with sonobuoy calibration data to correct :raw-data" to absolute sound pressure levels. The variation of omnidirectional levels with range from the beach as a function ...

  18. Ambient noise and the design of begging signals

    OpenAIRE

    Marty L. Leonard; Horn, Andrew G

    2005-01-01

    The apparent extravagance of begging displays is usually attributed to selection for features, such as loud calls, that make the signal costly and hence reliable. An alternative explanation, however, is that these design features are needed for effective signal transmission and reception. Here, we test the latter hypothesis by examining how the begging calls of tree swallow (Tachycineta bicolor) nestlings and the response to these calls by parents are affected by ambient noise. In a field stu...

  19. Depth Profiling Ambient Noise in the Deep Ocean

    Science.gov (United States)

    Barclay, David Readshaw

    Deep Sound is an un-tethered, free-falling acoustic platform designed to profile the ambient noise field in the ocean from the surface to a pre-programmed depth, at which point a ballast weight is dropped and the instrument returns to the surface under its own buoyancy. Three iterations of the instrument, Mk I, II and III, have been designed, built and tested, the first two rated to descend to 9 km and the third to a full ocean depth of 11 km. During a deployment of the instrument, vertically and horizontally spaced hydrophones continuously record the ambient noise pressure time series over a large bandwidth (5 Hz -- 40 kHz), returning the power spectral density, vertical and horizontal coherence as a function of depth. Deep Sound Mk I and Mk II have been deployed down to 9 km depth in the Mariana Trench and Mk I has descended three times to 5 km, 5.5 km and 6 km in the Philippine Sea. The data reported here examines the depth-dependence of the power spectrum, vertical coherence and directionality of rain and wind noise in the Philippine Sea. Acoustic estimates of rainfall rates and wind speeds are made from the surface to 5.5 km and 6 km respectively and compared to surface meteorological measurements. The depth-dependence of the accuracy of these estimates is relatively small and found to improve with depth. A coherence fitting procedure is employed to return ambient noise directionality and provide information on the spatial variability of an overhead rainstorm. With moderate 7-10 m/s winds, downward propagating noise from directly overhead dominates the noise field directionality from the surface to 6 km. Using the wind generated surface noise and the depth dependence of the spectral slope over the band 1 -- 10 kHz, the frequency dependence of the absorption due to sea water is estimated and used to infer a mean water column value of pH.

  20. Robust seismic velocity change estimation using ambient noise recordings

    Science.gov (United States)

    Daskalakis, E.; Evangelidis, C. P.; Garnier, J.; Melis, N. S.; Papanicolaou, G.; Tsogka, C.

    2016-06-01

    We consider the problem of seismic velocity change estimation using ambient noise recordings. Motivated by Zhan et al., we study how the velocity change estimation is affected by seasonal fluctuations in the noise sources. More precisely, we consider a numerical model and introduce spatio-temporal seasonal fluctuations in the noise sources. We show that indeed, as pointed out by Zhan et al., the stretching method is affected by these fluctuations and produces misleading apparent velocity variations which reduce dramatically the signal to noise ratio of the method. We also show that these apparent velocity variations can be eliminated by an adequate normalization of the cross-correlation functions. Theoretically we expect our approach to work as long as the seasonal fluctuations in the noise sources are uniform, an assumption which holds for closely located seismic stations. We illustrate with numerical simulations in homogeneous and scattering media that the proposed normalization significantly improves the accuracy of the velocity change estimation. Similar behaviour is also observed with real data recorded in the Aegean volcanic arc. We study in particular the volcano of Santorini during the seismic unrest of 2011-2012 and observe a decrease in the velocity of seismic waves which is correlated with GPS measured elevation.

  1. 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.

  2. Ambient Noise Tomography of central Java, with Transdimensional Bayesian Inversion

    Science.gov (United States)

    Zulhan, Zulfakriza; Saygin, Erdinc; Cummins, Phil; Widiyantoro, Sri; Nugraha, Andri Dian; Luehr, Birger-G.; Bodin, Thomas

    2014-05-01

    Delineating the crustal structure of central Java is crucial for understanding its complex tectonic setting. However, seismic imaging of the strong heterogeneity typical of such a tectonically active region can be challenging, particularly in the upper crust where velocity contrasts are strongest and steep body wave ray-paths provide poor resolution. We have applied ambient noise cross correlation of pair stations in central Java, Indonesia by using the MERapi Amphibious EXperiment (MERAMEX) dataset. The data were collected between May to October 2004. We used 120 of 134 temporary seismic stations for about 150 days of observation, which covered central Java. More than 5000 Rayleigh wave Green's function were extracted by cross-correlating the noise simultaneously recorded at available station pairs. We applied a fully nonlinear 2D Bayesian inversion technique to the retrieved travel times. Features in the derived tomographic images correlate well with previous studies, and some shallow structures that were not evident in previous studies are clearly imaged with Ambient Noise Tomography. The Kendeng Basin and several active volcanoes appear with very low group velocities, and anomalies with relatively high velocities can be interpreted in terms of crustal sutures and/or surface geological features.

  3. 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.

  4. Infrasonic ambient noise interferometry from correlations of microbaroms

    Science.gov (United States)

    Haney, M.M.

    2009-01-01

    We show that microbaroms, continuous infrasound fluctuations resulting from the interaction of the ocean with the atmosphere, have long-range correlation properties that make it possible to estimate the impulse response between two microphones from passive recordings. The processing is analogous to methods employed in the emerging field of ambient noise seismology, where the random noise source is the ocean coupling with the solid Earth (microseisms) instead of the atmosphere (microbaroms). We find that time-dependent temperature fields and temperature inversions determine the character of infrasonic impulse responses at Fourpeaked Volcano in Alaska. Applications include imaging and monitoring the gross structure of the Earth's atmospheric boundary layer. Copyright 2009 by the American Geophysical Union.

  5. Origin of the chemical noise in ambient mass spectrometry

    International Nuclear Information System (INIS)

    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)

  6. Investigating a deep geothermal reservoir using ambient noise correlation

    Science.gov (United States)

    Lehujeur, Maximilien; Vergne, Jérôme; Schmittbuhl, Jean; Maggi, Alessia

    2014-05-01

    Knowledge of the geological structures and their evolution in time is necessary to understand and predict the behavior of geothermal reservoirs. In this study, we focus on the site of Rittershoffen (North East of France), next to the site of Soultz-sous-Forêts (GEIE-EMC), where a geothermal plant is about to be installed (ECOGI project). An Enhanced Geothermal System (EGS) will be established at ~3000m depth using a combination of 2 wells. Our objective is to characterize the reservoir (~10 km2 large / 3 km deep) through the estimation of the seismic velocities as a function of space and time in order to follow the reservoir life during the exploitation period. Several studies over the past 10 years have shown that correlation of seismic noise between seismic receivers can be used to infer the medium properties and follow their evolution in time. Conversely to the use of individual micro seismic events, ambient noise provides continuous information, and does not require knowledge of seismic source locations. The analyzed data come from a permanent network of short period velocimeters extending on a radius of 15 km around the two geothermal sites. Additionally, two temporary small-aperture arrays have been deployed in the area. Within the frequency range used in this study (0.2 to 5 Hz), the ambient noise has a composite origin. A careful analysis of this noise is performed in order to measure dispersion characteristics of surface waves between each pair of receivers. The inversion of these dispersion curves provides a preliminary velocity model which is in good agreement with the sonic measurements performed in the borehole. Some preliminary results will be shown about temporal variability of the coda of the correlation functions and the ability to monitor temporal variations in the reservoir.

  7. Estimating correlations of neighbouring frequencies in ambient seismic noise

    Science.gov (United States)

    Liu, Xin; Ben-Zion, Yehuda

    2016-08-01

    Extracting accurate empirical Green's functions from the ambient seismic noise field requires the noise to be fully diffuse and that different frequency components are not correlated. Calculating a matrix of correlation coefficients of power spectral samples can be used to estimate deviations from a fully diffuse random noise field in the analysed frequency range. A fully diffuse field has correlations only in a narrow region around the diagonal of the matrix, with frequency resolution inversely proportional to length of the used time window. Analysis of low-frequency data (0.005-0.6 Hz) recorded by three broad-band stations of the southern California seismic network reveals three common types of correlations, manifested in the correlation coefficient matrix as square, diagonal halo and correlated stripes. Synthetic calculations show that these types of signatures in the correlation coefficient matrix can result from certain combinations of cross-frequency correlated random components and diffuse field. The analysis of observed data indicates that the secondary microseismic peak around 0.15 Hz is correlated with its neighbouring frequencies, while the primary peak around 0.06 Hz is more diffuse. This suggests that the primary and secondary peaks may be associated with somewhat different physical origins. In addition, significant correlation of frequencies below that of the primary microseismic peak suggests that the very low frequencies noise is less scattered during propagation. The power spectra recorded by a station close to the edge of the Los Angeles basin is higher compared to data recorded by stations outside the basin perhaps because of enhanced basin reverberations and/or closer proximity to the ocean. This and other regional variations should be tested further using data from many more stations.

  8. Single-station monitoring of volcanoes using seismic ambient noise

    Science.gov (United States)

    De Plaen, Raphael S. M.; Lecocq, Thomas; Caudron, Corentin; Ferrazzini, Valérie; Francis, Olivier

    2016-08-01

    Seismic ambient noise cross correlation is increasingly used to monitor volcanic activity. However, this method is usually limited to volcanoes equipped with large and dense networks of broadband stations. The single-station approach may provide a powerful and reliable alternative to the classical "cross-station" approach when measuring variation of seismic velocities. We implemented it on the Piton de la Fournaise in Reunion Island, a very active volcano with a remarkable multidisciplinary continuous monitoring. Over the past decade, this volcano has been increasingly studied using the traditional cross-correlation technique and therefore represents a unique laboratory to validate our approach. Our results, tested on stations located up to 3.5 km from the eruptive site, performed as well as the classical approach to detect the volcanic eruption in the 1-2 Hz frequency band. This opens new perspectives to successfully forecast volcanic activity at volcanoes equipped with a single three-component seismometer.

  9. Trans-dimensional ambient noise tomography of the northeast Asia

    Science.gov (United States)

    Kim, Seongryong; Tkalčić, Hrvoje; Rhie, Junkee; Chen, Youlin

    2016-04-01

    A trans-dimensional and hierarchical Bayesian tomography is performed to estimate spatial variations of shear wave velocity and provide the uncertainty in the northeast Asia region from the ambient noise data. The method accounts for irregular data distribution and sensitivity using adaptive partition property of Voronoi cells. Importantly, the number of basis functions used to parameterise the Earth model in the inversion and the level of data noise are implicitly balanced by the information contained in the data (and treated as free parameters in the inversions). Thereby more reliable models and their rigorous uncertainties are estimated by avoiding over- or under-estimation and explicit regularisation. We measure Rayleigh wave phase and group velocity (8-70 s) for available inter-station paths between more than 300 broadband stations. The obtained group and phase velocity maps reveal characteristic features beneath the former (East Sea also known as Japan Sea) and the current back-arc (Okinawa trough) regions, where relatively high and low velocities are estimated at intermediate (20-40 s) and longer periods (50-60 s), respectively. We observe that the low velocity anomalies extend to beneath intraplate volcanoes in the northeast China and the Korean Peninsula. Based on the depth sensitivity of surface wave dispersions and previous geological evidences, we argue that the intraplate volcanism in this region might be influenced by sub-lithospheric processes related to the subduction of the Pacific and Philippine Sea plates.

  10. Regional Ambient Noise Tomography in the Eastern Alps of Europe

    Science.gov (United States)

    Behm, Michael; Nakata, Nori; Bokelmann, Götz

    2016-08-01

    We present results from ambient noise tomography applied to temporary seismological stations in the easternmost part of the Alps and their transition to the adjacent tectonic provinces (Vienna Basin, Bohemian Massif, Southern Alps, Dinarides). By turning each station into a virtual source, we recover surface waves in the frequency range between 0.1 and 0.6 Hz, which are sensitive to depths of approximately 2-15 km. The utilization of horizontal components allows for the analysis of both Rayleigh and Love waves with comparable signal-to-noise ratio. Measured group wave dispersion curves between stations are mapped to local cells by means of a simultaneous inverse reconstruction technique. The spatial reconstruction for Love-wave velocities fails in the central part of the investigated area, and we speculate that a heterogeneous noise source distribution is the cause for the failure. Otherwise, the obtained group velocity maps correlate well with surface geology. Inversion of Rayleigh-wave velocities for shear-wave velocities along a vertical N-S section stretching from the Bohemian Massif through the Central Alps to the Southern Alps and Dinarides reveals a mid-crustal low-velocity anomaly at the contact between the Bohemian Massif and the Alps, which shows a spatial correlation with the P-wave velocity structure and the low-frequency component of the magnetic anomaly map. Our study is validated by the analysis of resolution and accuracy, and we further compare the result to shear-wave velocity models estimated from other active and passive experiments in the area.

  11. Ambient Noise Tomography of the Huatung Basin Offshore Eastern Taiwan

    Science.gov (United States)

    Liu, Ruo-Shan; Huang, Tzu-Ying; Chen, Ying-Nien; Chen, Chin-Wu

    2016-04-01

    The island of Taiwan is a young and active orogenic belt resulting from the oblique subduction and collision between the Eurasian Plate and the Philippine Sea Plate, where the Philippine Sea Plate is converging northwesterly toward the Eurasian Plate at a rate of 81 mm/year. In Southern Taiwan, the Eurasian Plate is subducting eastward beneath the Philippine Sea Plate along the Manila Trench. Offshore northeastern Taiwan, on the other hand, the Philippine Sea Plate is subducting northward beneath the Eurasian Plate along the Ryukyu Trench. Between the Ryukyu Trench and Luzon Arc lies the Huatung Basin, a 4000 m deep ocean basin in the westernmost part of the western Philippine Sea Basin. The intertwined tectonic processes result in complex geological structures of Taiwan, from surface to the crust and uppermost mantle. Previous seismic tomographic studies have suggested the effects of collision and subduction on the tectonic structures beneath Taiwan, but the details remain elusive, especially in the crustal depth range, due to limited station coverage and earthquake sources. Recently, ambient noise analysis fills the gap by offering high resolution tomographic model at crustal depths, derived from frequency-dependent Rayleigh wave measurements using noise cross-correlations. A most recent ambient noise tomography of Taiwan has revealed the presence of distinct layered deformation pattern throughout the crust, indicating integrated effect of collision and subduction on the evolution of Taiwan orogeny. However, this study used only land station and thus did not resolve structure in the surrounding region of the island. In our work, we aim to expand such analysis to offshore eastern Taiwan, taking advantage of the data from an OBS network as part of the recent TAIGER experiment. We integrate the data of OBS with that of selected land stations along the east coast, deriving Rayleigh wave Green functions from cross-correlation between all available station pairs. We

  12. A Complexity-Based Approach for the Detection of Weak Signals in Ocean Ambient Noise

    Directory of Open Access Journals (Sweden)

    Shashidhar Siddagangaiah

    2016-03-01

    Full Text Available There are numerous studies showing that there is a constant increase in the ocean ambient noise level and the ever-growing demand for developing algorithms for detecting weak signals in ambient noise. In this study, we utilize dynamical and statistical complexity to detect the presence of weak ship noise embedded in ambient noise. The ambient noise and ship noise were recorded in the South China Sea. The multiscale entropy (MSE method and the complexity-entropy causality plane (C-H plane were used to quantify the dynamical and statistical complexity of the measured time series, respectively. We generated signals with varying signal-to-noise ratio (SNR by varying the amplification of a ship signal. The simulation results indicate that the complexity is sensitive to change in the information in the ambient noise and the change in SNR, a finding that enables the detection of weak ship signals in strong background ambient noise. The simulation results also illustrate that complexity is better than the traditional spectrogram method, particularly effective for detecting low SNR signals in ambient noise. In addition, complexity-based MSE and C-H plane methods are simple, robust and do not assume any underlying dynamics in time series. Hence, complexity should be used in practical situations.

  13. Understanding the dynamics of a geyser using seismic ambient noise

    Science.gov (United States)

    Cros, Estelle; Roux, Philippe; Vandemeulebrouck, Jean; Kedar, Sharon

    2010-05-01

    Old Faithful Geyser in Yellowstone National Park, Wyoming, is one of the most studied geysers in the world. The predictability, the repeatability and the short time lag, ~1.5 hour, between 2 eruptions make the study convenient. The surface expression of the geyser is a 4m high, 60m wide mound with an approximately 2m x 1m opening at the top, which permits to deploy a dense network of sensors closed to the orifice. In 1992, Sharon Kedar deployed 96 vertical geophones in a tight grid over the geyser's dome. The geophones recorded the ambient seismic noise during an entire eruptive cycle, including a short period of quiet seismic activity. The survey was completed by seven shots carried out with a sledge hammer. The signal consists in a series of impulsive events, most likely due to bubble collapse in boiling water areas inside the geyser's plumbing system. The aim of this study is to locate the sources of these events. We revisited a 10 minutes-long data set from S. Kedar's records and processed the signal using a Matched Field Processing (MFP) algorithm derived from ocean acoustics. The cross-correlation of the signals recorded by the 96 geophones showed a great level of coherency between the sensors, which is a pre-requisite to use MFP. This method introduced in geophysics by Capon is based on comparing forward modelling solutions of the wave equation in a grid search with acquired data, measured on an array of motion sensors. The process consists in placing a test source at each point of the grid search, computing the acoustic field corresponding at all the elements of the array and then correlating this modelled field with the data. The correlation is maximum when the candidate point source is co-located with the true point source. We used both linear (Bartlett) and non linear (MVDR : Minimum Variance Distorsionless) processors. The MFP processor was performed either incoherently from the raw ambient noise data or coherently from the cross-correlated traces

  14. Anisotropic Tomography of Portugal (West Iberia) from ambient seismic noise

    Science.gov (United States)

    Silveira, Graça; Stutzmann, Éléonore; Schimmel, Martin; Dias, Nuno; Kiselev, Sergey; Custódio, Susana; Dundar, Suleyman

    2016-04-01

    Located on the western Iberian Peninsula, Portugal constitutes a key area for accretionary terrane and basin research, providing the best opportunity to probe a crustal formation shaped by the Paleozoic Variscan orogeny followed by the Mesozoic-Cenozoic extensions. The geology of Portugal documents a protracted history from Paleozoic basement formation to the Mesozoic opening of the North Atlantic Ocean. The inheritance of such complex geologic history is yet to be fully determined, playing an important role in the current geodynamic framework influencing, for example, the observed regional seismicity. The physical properties of its crust have largely remained undetermined so far, with unevenly distributed knowledge on the spatial distributions of a detailed crustal structure. Also, the deep seismic reflection/refraction surveys conducted in Western Iberia do not provide a clear picture of the regional characteristics of the crust. Using Seismic Broad Band observations from a dense temporary deployment, conducted between 2010 and 2012 in the scope of the WILAS project and covering the entire Portuguese mainland, we computed a 3D anisotropic model from ambient seismic noise. The dispersion measurements were computed for each station pair using empirical Green's functions generated by cross-correlating one-day-length seismic ambient-noise records. After dispersion analysis, group velocity measurements were regionalized to obtain 2D anisotropic tomographic images. 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 anisotropic model, using a bayesian approach. A simulated annealing method, in which the number of splines that describes the model, is adapted within the inversion. The models are jointly interpreted with the models gathered from Ps receiver functions as well as with the regional seismicity, enabling to obtain a more detailed picture of the crustal

  15. Recommended noise criteria for siting industrial facilities near residential communities with extremely low ambient sound levels

    Science.gov (United States)

    Hessler, David M.

    2005-09-01

    Noise limits or criteria in many residential communities are based on an allowable increase in level above the prevailing ambient sound level, usually on the order of 3 to 5 dBA. The theory is that such a small increase results in masking of the new or existing intruding facility noise by the environmental ambient sound. However, many facilities are planned for installation or already exist in remote and very quiet ambient environments with residual levels as low as 25 dBA during the day or nighttime. This paper summarizes a study conducted to determine appropriate criteria in such remote and quiet areas where little or no noise masking will occur from ambient sources. The paper discusses both audible noise measured by the A-weighted level, low frequency noise characterized by the C-weighted level and tonal noise.

  16. Ambient noise tomography of the East African Rift in Mozambique

    Science.gov (United States)

    Domingues, Ana; Silveira, Graça; Ferreira, Ana M. G.; Chang, Sung-Joon; Custódio, Susana; Fonseca, João F. B. D.

    2016-03-01

    Seismic ambient noise tomography is applied to central and southern Mozambique, located in the tip of the East African Rift (EAR). The deployment of MOZART seismic network, with a total of 30 broad-band stations continuously recording for 26 months, allowed us to carry out the first tomographic study of the crust under this region, which until now remained largely unexplored at this scale. From cross-correlations extracted from coherent noise we obtained Rayleigh wave group velocity dispersion curves for the period range 5-40 s. These dispersion relations were inverted to produce group velocity maps, and 1-D shear wave velocity profiles at selected points. High group velocities are observed at all periods on the eastern edge of the Kaapvaal and Zimbabwe cratons, in agreement with the findings of previous studies. Further east, a pronounced slow anomaly is observed in central and southern Mozambique, where the rifting between southern Africa and Antarctica created a passive margin in the Mesozoic, and further rifting is currently happening as a result of the southward propagation of the EAR. In this study, we also addressed the question concerning the nature of the crust (continental versus oceanic) in the Mozambique Coastal Plains (MCP), still in debate. Our data do not support previous suggestions that the MCP are floored by oceanic crust since a shallow Moho could not be detected, and we discuss an alternative explanation for its ocean-like magnetic signature. Our velocity maps suggest that the crystalline basement of the Zimbabwe craton may extend further east well into Mozambique underneath the sediment cover, contrary to what is usually assumed, while further south the Kaapval craton passes into slow rifted crust at the Lebombo monocline as expected. The sharp passage from fast crust to slow crust on the northern part of the study area coincides with the seismically active NNE-SSW Urema rift, while further south the Mazenga graben adopts an N-S direction

  17. Ambient seismic noise tomography of Jeju Island, South Korea

    Science.gov (United States)

    Lee, S. J.; Rhie, J.; Kim, S.; Kang, T. S.; Kim, Y.

    2015-12-01

    Jeju Island, formed by Cenozoic basaltic eruptions, is an island off the southern coast of the Korean Peninsula. This volcanic island is far from the plate boundaries and the fundamental cause of the volcanic activity in this region is not understood well. To understand the origin of the island, resolving the detailed seismic velocity structures is crucial. Therefore, we applied ambient noise tomography to study the velocity structures of the island. Continuous waveform data recorded at 20 temporary and 3 permanent broad-band seismic stations are used. The group and phase velocity dispersion curves of the fundamental mode Rayleigh waves are extracted from cross-correlograms for 253 station pairs by adopting multiple filter technique. The fast marching method and the subspace method are jointly applied to construct 2-D group and phase velocity maps for periods ranging between 1 and 15 s. 1-D shear wave velocity models and their uncertainties are estimated by the Bayesian technique. The optimal number of the layers are determined at the end of the burn-in period based on the Bayesian Information Criteria (BIC). Final 3-D velocity model of the island is constructed by compiling 1-D models. In our 3-D model, a distinct low velocity anomaly appears beneath Mt. Halla from surface to about 6 km depth. The surficial extent of the anomaly is more or less consistent with the surface geologic feature of the third-stage basaltic eruption reported by previous studies but the vertical extension of the anomaly is not well constrained. To improve the velocity model, especially enhance the vertical resolution of the anomaly, we will apply joint analysis of the surface wave dispersions and teleseismic receiver functions. The improved model will provide more information to infer the tectonic or volcanic implications of the anomaly and unravel the origin of the strange volcanic island in South Korea.

  18. The Effects of Ambient Conditions on Helicopter Harmonic Noise Radiation: Theory and Experiment

    Science.gov (United States)

    Greenwood, Eric; Sim, Ben W.; Boyd, D. Douglas, Jr.

    2016-01-01

    The effects of ambient atmospheric conditions, air temperature and density, on rotor harmonic noise radiation are characterized using theoretical models and experimental measurements of helicopter noise collected at three different test sites at elevations ranging from sea level to 7000 ft above sea level. Significant changes in the thickness, loading, and blade-vortex interaction noise levels and radiation directions are observed across the different test sites for an AS350 helicopter flying at the same indicated airspeed and gross weight. However, the radiated noise is shown to scale with ambient pressure when the flight condition of the helicopter is defined in nondimensional terms. Although the effective tip Mach number is identified as the primary governing parameter for thickness noise, the nondimensional weight coefficient also impacts lower harmonic loading noise levels, which contribute strongly to low frequency harmonic noise radiation both in and out of the plane of the horizon. Strategies for maintaining the same nondimensional rotor operating condition under different ambient conditions are developed using an analytical model of single main rotor helicopter trim and confirmed using a CAMRAD II model of the AS350 helicopter. The ability of the Fundamental Rotorcraft Acoustics Modeling from Experiments (FRAME) technique to generalize noise measurements made under one set of ambient conditions to make accurate noise predictions under other ambient conditions is also validated.

  19. Ambient Noise Surface Wave Tomography for Geotechnical Monitoring Using "Large N" Distributed Acoustic Sensing

    Science.gov (United States)

    Ajo Franklin, J. B.; Lindsey, N.; Martin, E. R.; Wagner, A. M.; Robertson, M.; Bjella, K.; Gelvin, A.; Ulrich, C.; Wu, Y.; Freifeld, B. M.; Daley, T. M.; Dou, S.

    2015-12-01

    Surface wave tomography using ambient noise sources has found broad application at the regional scale but has not been adopted fully for geotechnical applications despite the abundance of noise sources in this context. The recent development of Distributed Acoustic Sensing (DAS) provides a clear path for inexpensively recording high spatial resolution (survey as well as direct-push data on ice content. We also compare vintages of ambient noise DAS data to evaluate the short-term repeatability of the technique in the face of changing noise environments. The resulting dataset demonstrates the utility of using DAS for real-time shear-modulus monitoring in support of critical infrastructure.

  20. Investigation of ambient seismic noise using seismic interferometry in western Montana

    Science.gov (United States)

    Krzywosz, Natalia

    Passive seismic interferometry is a process by which ambient noise data recorded at different seismic stations can be cross-correlated to estimate Green's functions. In the past, both surface waves and body waves have successfully been extracted by cross-correlation of ambient noise data on both regional and global scales. In this study, I have generated Matlab code to simulate an application of seismic interferometry on a synthetic model with pre-defined layers and p-wave velocities. For areas with known velocity models, the Matlab code produced in this study can be used to generate synthetic seismograms, and model the effects of cross-correlation on receiver responses. In order to develop a general understanding of the ambient noise wavefield in western Montana, a spectral analysis program was developed in Matlab. This program is used to process ambient noise data from the Transportable Array (TA) Seismographic Network, and to generate its power spectral density plots and probability density functions. The detailed spectral analysis provides some insight to the ambient noise sources, and their energy distribution throughout western Montana. In addition, an attempt was made to preprocess ambient noise data from the TA array in Matlab for later use. Although preprocessing of the data was successful, limitations in computing power and time, allowed for temporal stacking of only one month of data. The one month period was not long enough to produce Green's functions which contain coherent body waves.

  1. Retrieving surface waves from ambient seismic noise using seismic interferometry by multidimensional deconvolution

    NARCIS (Netherlands)

    Van Dalen, Karel N.; Mikesell, T. Dylan; Ruigrok, Elmer N.; Wapenaar, Kees

    2015-01-01

    Retrieving virtual source surface waves from ambient seismic noise by cross correlation assumes, among others, that the noise field is equipartitioned and the medium is lossless. Violation of these assumptions reduces the accuracy of the retrieved waves. A point-spread function computed from the sam

  2. Periodic changes in ambient noise: possible causes and implications for long term prediction

    NARCIS (Netherlands)

    Ainslie, M.A.

    2013-01-01

    Periodic changes in ambient noise have been observed on various timescales. Available long term measurements of periodic noise fluctuations are reviewed, with particular emphasis on those exhibiting periodicity appearing to coincide with that of the Sun. Evidence is offered supporting the suggestion

  3. Developments in ambient noise analysis for the characterization of dynamic response of slopes to seismic shaking

    Science.gov (United States)

    Del Gaudio, Vincenzo; Wasowski, Janusz

    2016-04-01

    In the last few decades, we have witnessed a growing awareness of the role of site dynamic response to seismic shaking in slope failures during earthquakes. Considering the time and costs involved in acquiring accelerometer data on landslide prone slopes, the analysis of ambient noise offers a profitable investigative alternative. Standard procedures of ambient noise analysis, according to the technique known as HVNR or Nakamura's method, were originally devised to interpret data under simple site conditions similar to 1D layering (flat horizontal layering infinitely extended). In such cases, conditions of site amplification, characterized by a strong impedance contrast between a soft surface layer and a stiff bedrock, result in a single pronounced isotropic maximum of spectral ratios between horizontal and vertical component of ambient noise. However, previous studies have shown that the dynamic response of slopes affected by landslides is rather complex, being characterized by multiple resonance peaks with directional variability, thus, the use of standard techniques can encounter difficulties in providing reliable information. A new approach of data analysis has recently been proposed to exploit the potential of information content of Rayleigh waves present in ambient noise, with regard to the identification of frequency and orientation of directional resonance. By exploiting ground motion ellipticity this approach can also provide information on vertical distribution of S-wave velocity, which controls site amplification factors. The method, based on the identification of Rayleigh wave packets from instantaneous polarization properties of ambient noise, was first tested using synthetic signals in order to optimize the data processing system. Then the improved processing scheme is adopted to re-process and re-interpret the ambient noise data acquired on landslide prone slopes around Caramanico Terme (central Italy), at sites monitored also with accelerometer

  4. 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.

  5. Ambient awareness: From random noise to digital closeness in online social networks

    OpenAIRE

    Levordashka, Ana; Utz, Sonja

    2016-01-01

    Ambient awareness refers to the awareness social media users develop of their online network in result of being constantly exposed to social information, such as microblogging updates. Although each individual bit of information can seem like random noise, their incessant reception can amass to a coherent representation of social others. Despite its growing popularity and important implications for social media research, ambient awareness on public social media has not been studied empiricall...

  6. Imaging the Jakarta Basin with Seismic Ambient Noise

    Science.gov (United States)

    Saygin, Erdinc; Cummins, Phil; Pandhu, Rakhindro; Murjaya, Jaya; Irsyam, Masyhur; Pranata, Bayu

    2014-05-01

    Jakarta, the capital of Indonesia, is one of the most populous cities in the world with a population over 28 million including the metro area. In July 2012, 8 short period and broadband seismic stations were deployed progressively to record seismic noise at 36 different locations in Jakarta for a duration of 31 days. The recorded seismic noise is then cross-correlated between the simultaneously operated stations for retrieving the inter-station Green's functions. The traveltimes of Rayleigh wave Green's functions measured at different periods are later inverted with nonlinear tomography. The results mark the presence of a very low velocity body due to the alluvial deposits, which cover most of the Jakarta area. In October 2013, we deployed 52 broadband stations across Jakarta with a typical station spacing of 2 km for a duration of 4 months. We divide the city to 3 sectors, which each area was covered by a dense deployment each subsequent month. The recorded noise is used in high-resolution 2D Bayesian tomography to map the 2D seismic velocity model of the city. The resulting models will be used in estimating the seismic amplification and other seismic hazards of the city.

  7. Spatial coherences of the sound pressure and the particle velocity in underwater ambient noise

    Institute of Scientific and Technical Information of China (English)

    YAN Jin; LUO Xianzhi; HOU Chaohuan

    2007-01-01

    The spatial coherences were investigated between the sound pressure and the three orthogonal components of the particle velocity in underwater ambient noise. Based on the ray theory, integral expression was derived for the spatial coherence matrix of the sound pressure and the particle velocity in a stratified ocean with dipole noise sources homogenously distributed on the surface. The integrand includes a multiplying factor of the vertical directivity of the noise intensity, and the layered ocean environment affects the spatial coherences via this directivity factor. For a shallow water environment and a semi-infinite homogenous medium, the coherence calculation results were given. It was showed that the sound speed profile and the sea bottom could not be neglected in determining the spatial coherences of the ambient noise vector field.

  8. On the accuracy of long-period Rayleigh waves extracted from ambient noise

    Science.gov (United States)

    Xie, Jun; Yang, Yingjie; Ni, Sidao

    2016-07-01

    The aim of this paper is to assess the accuracy of the long-period (50-250 s) surface waves extracted from cross-correlation functions (CCF) of ambient noise. First, we compare waveforms of Empirical Green's functions (EGF) converted from CCF with their synthetics, and also compare seismograms from a ground truth earthquake with their synthetics, through numerical simulations using a common 3-D model. We then quantify the accuracy of EGFs by comparing two sets of time-shifts between the observed waveforms and the synthetics: one set for the ground truth earthquake and the other set for EGFs. Second, we compare Rayleigh wave phase velocity dispersion measurements from ambient noise and those from earthquake data in both global and regional studies. Through these comparisons, we conclude that both the dispersion curves and waveforms from noise data are consistent with their counterparts from earthquake data in the long-period band. The long-period surface waves from ambient noise are as accurate as those from earthquake data, and can be included in both global and regional ambient noise tomography and provide complementary data to constrain the lithospheric and asthenospheric structures.

  9. Impact of wind on ambient noise recorded by seismic array in northern Poland

    Science.gov (United States)

    Lepore, Simone; Markowicz, Krzysztof; Grad, Marek

    2016-06-01

    Seismic interferometry and beam-forming techniques were applied to the ambient noise recorded during January 2014 at the `13 BB star' array composed of thirteen seismic stations located in northern Poland. The circular and symmetric geometry of the array allowed the evaluation of the azimuths of noise sources and the velocities of recovered surface waves with a good reliability. After having pre-processed the raw records of the ambient noise in time- and frequency-domain, we studied the associated power spectral density to identify the frequency bands suitable for the recovery of the surface waves. Then the cross-correlation was performed between all the station pairs of the array to retrieve the Green's function, from which the velocity range of the surface waves can be determined. Making use of that analysis, the direction of the noise wavefield was linked to the maximum amplitude of the beam-power, estimated by the mixing in the frequency-domain of all the corresponding noise records. The results were related day by day to the mean wind velocity around Europe at 10 m above ground level obtained from global surveys carried out during the same month. Significant correlation between the direction of maximum beam-power associated to the ambient noise recorded at `13 BB star' and the average wind velocity was found.

  10. Ambient noise during rough weather and cyclones in the shallow Bay of Bengal

    Science.gov (United States)

    Sanjana, M. C.; Latha, G.; Thirunavukkarasu, A.

    2014-07-01

    This paper presents ambient noise analysis during rough weather, using time series measurements from an automated noise measurement system in the shallow southwest Bay of Bengal during October-November 2010. The period witnessed low-pressure events including depressions and cyclones, with JAL cyclone passing close to the measurement site. The time series noise level shows a shift in mid-October, after which deep depressions and cyclones formed, with an average increase of 5-10 dB in the lower band and 2-3 dB in the higher band of frequencies. Furthermore, correlation between noise level and wave height (data from wave rider buoy deployed at the site) for sea state scale 3 and above shows good correlation with an increase in noise level with increase in wave height, the effect being most pronounced at 0.5 kHz. The noise captured during JAL was analysed to identify the spectrum components due to convective precipitation and heavy wind/wave activity and shows anomalously high levels during the crossing of the cyclone. Rain noise spectra from the rain bands associated with the wall of the cyclone are reported. This has been correlated with radar reflectivity measurements to ascertain the presence of rain, and discriminate between convective and stratiform types. Also, vertical directionality pattern of ambient noise during JAL showed clearly distinct surface contributions. On the whole, knowledge of ambient noise fields during high sea states and precipitation is useful in optimizing SONAR performance. The findings at the study site have been compared with measurements from other shallow water locations during rough weather.

  11. The life cycle of a sudden stratospheric warming from infrasonic ambient noise observations

    NARCIS (Netherlands)

    Smets, P.S.M.; Evers, L.G.

    2014-01-01

    A method is presented to study the life cycle of a SSW using infrasonic ambient noise observations. The potential of infrasound is shown to provide the missing observations required by numerical weather prediction to better resolve the upper atmosphere. The 2009 major SSW is reanalyzed using the Eve

  12. Sub-bottom profiling with ambient noise measured on a drifting vertical array

    NARCIS (Netherlands)

    Harrison, C.H.; Schippers, P.; Snellen, M.; Weterings, A.

    2005-01-01

    The angle and frequency dependent reflective properties of the seabed can be determined from beam-steered ambient noise measurements on a vertical array of hydrophones. From the up-to-down ratio the beam-smeared modulus square of the plane wave reflection coefficient is obtained. Geo-acoustic parame

  13. Monitoring southwest Greenland's ice sheet melt with ambient seismic noise.

    Science.gov (United States)

    Mordret, Aurélien; Mikesell, T Dylan; Harig, Christopher; Lipovsky, Bradley P; Prieto, Germán A

    2016-05-01

    The Greenland ice sheet presently accounts for ~70% of global ice sheet mass loss. Because this mass loss is associated with sea-level rise at a rate of 0.7 mm/year, the development of improved monitoring techniques to observe ongoing changes in ice sheet mass balance is of paramount concern. Spaceborne mass balance techniques are commonly used; however, they are inadequate for many purposes because of their low spatial and/or temporal resolution. We demonstrate that small variations in seismic wave speed in Earth's crust, as measured with the correlation of seismic noise, may be used to infer seasonal ice sheet mass balance. Seasonal loading and unloading of glacial mass induces strain in the crust, and these strains then result in seismic velocity changes due to poroelastic processes. Our method provides a new and independent way of monitoring (in near real time) ice sheet mass balance, yielding new constraints on ice sheet evolution and its contribution to global sea-level changes. An increased number of seismic stations in the vicinity of ice sheets will enhance our ability to create detailed space-time records of ice mass variations. PMID:27386524

  14. Body Waves Revealed by Spatial Stacking on Long-Term Cross-Correlation of Ambient Noise

    Institute of Scientific and Technical Information of China (English)

    Kai Wang; Yinhe Luo; Kaifeng Zhao; Limeng Zhang

    2014-01-01

    ABSTRCT: Theoretical and experimental studies indicate that complete Green’s Function can be retrieved from cross-correlation in a diffuse field. High SNR (signal-to-noise ratio) surface waves have been extracted from cross-correlations of long-duration ambient noise across the globe. Body waves, not extracted in most of ambient noise studies, are thought to be more difficult to retrieve from regular ambient noise data processing. By stacking cross-correlations of ambient noise in 50 km inter-station distance bins in China, western United States and Europe, we observed coherent 20–100 s core phases (ScS, PKIKPPKIKP, PcPPKPPKP) and crustal-mantle phases (Pn, P, PL, Sn, S, SPL, SnSn, SS, SSPL) at distances ranging from 0 to 4 000 km. Our results show that these crustal-mantle phases show diverse characteristics due to different substructure and sources of body waves beneath different regions while the core phases are relatively robust and can be retrieved as long as stations are available. Further analysis indicates that the SNR of these body-wave phases depends on a compromise between stacking fold in spatial domain and the coherence of pre-stacked cross-correlations.Spatially stacked cross-correlations of seismic noise can provide new virtual seismograms for paths that complement earthquake data and that contain valuable information on the structure of the Earth. The extracted crustal-mantle phases can be used to study lithospheric heterogeneities and the robust core phases are significantly useful to study the deep structure of the Earth, such as detecting fine heterogeneities of the core-mantle boundary and constraining differential rotation of the inner core.

  15. A perspective on 30 years of progress in ambient noise: Source mechanisms and the characteristics of the sound field

    Science.gov (United States)

    Cato, Douglas H.

    2012-11-01

    The last 30 years has seen substantial progress in ocean ambient noise research, particularly in understanding the mechanisms of sound generation by the sources of ambient noise, the way in which the noise field is affected by sound propagation, and improvements in quantifying the relationship between noise and environmental parameters. This has led to significant improvements in noise prediction. Activity was probably strongest in the 1980s and 1990s, as evident, for example, in the Sea Surface Sound conferences and their published proceedings (four over 10 years). Although much of the application has been to sonar, there has also been interest in using ambient noise to measure properties of the environment and in its significance to marine life. There have been significant changes in the ambient noise itself over the last 30 years. The contribution from human activities appears to have increased, particularly that due to increases in shipping numbers. Biological noise has also increased with the significant increases in populations of some whale species following the cessation of broad scale whaling in the 1960s and early 1970s. Concern about the effects of noise on marine animals as well as the way they exploit the noise has led to renewed interest in ambient noise.

  16. Spatial variability of the ambient noise field associated with the Marginal Ice Zone and its relationship to environmental parameters

    OpenAIRE

    Biggs, Kristian Pedersen

    1988-01-01

    Approved for public release; distribution is unlimited During the month of July 1987 an acoustical experiment was conducted by the United States Naval Research Laboratory (NRL) in the East Greenland Sea Marginal Ice Zone (MIZ) . Ambient noise "hot spots" or concentrated areas of relatively high noise levels were found along the ice edge using a towed array. Ambient noise levels were obtained on 27 and 28 July using AN/SSQ-57A and AN/SSQ-57XN5 calibrated sonobuoys . The ...

  17. Stress Monitoring Potential of Ambient Noise Interferometry in Deep Mine Environments

    Science.gov (United States)

    Dales, P.; Audet, P.; Mercier, J. P.; de Beer, W.; Pascu, A.

    2015-12-01

    Understanding the response of the rock mass to mining is of key importance for the planning of mine operations as well as assessing and mitigating the seismic risk. For decades, studies have shown that passive source tomography, also called local earthquake tomography, can provide information on the rock mass response through the estimation of the temporal variation and 3D distribution (spatio-temporal variations) of stress. The spatio-temporal resolution afforded by passive source tomography depends on the seismicity rate and the location of microseismic events. In a mine, seismicity is not stationary, i.e. the locus and rate of seismicity vary with time, thus limiting the spatio-temporal resolution of this technique. Recent developments in the field of ambient noise seismic interferometry (Green's function retrieval from ambient noise) provide hints that continuous recordings of ambient vibrations collected around mines could be used to obtain information on the evolution and 3D distribution of the stress in the rock mass by providing measures of seismic travel times between pairs of sensors. In contrast to passive source tomography that relies on the distribution of seismic events, the resolution afforded by ambient noise interferometry tomography depends solely on the locations of sensors and the frequency content of the ambient noise. We present preliminary results which focus on the temporal stability of the estimated Green's functions, the effect of mine infrastructure on signal quality and preliminary methods to quantify stress changes in the rock mass. In addition, we present the adopted processing scheme built on the Apache Spark engine and demonstrate its effectiveness in parallelizing the computationally intensive cross-correlation routines.

  18. Crustal Structure of the Pakistan Himalayas from Ambient Noise and Seismic Rayleigh Wave Inversion

    Science.gov (United States)

    Li, A.

    2007-05-01

    The western Himalayan syntaxi is a unique feature resulted from the India-Asia collision and its formation remains poorly understood. To image crustal structure in the western syntaxi, we analyze Rayleigh waves from ambient seismic noise and earthquake data recorded during the Pakistan Broadband Seismic Experiment. The Pakistan experiment included 9 broadband stations with an aperture of ~200 km and operated from September to December in 1992. We compute cross-correlations of ambient noise data on an hourly base and stack all the cross-correlations for 70 days to produce the estimated Green functions. Power spectrum analysis shows that the dominant energy is from 0.15 to 0.25 Hz and from 0.05 to 0.07 Hz, consistent with the well-know background seismic noise. A phase with large amplitude appears at near zero time on almost all stacked cross- correlations and its origin is not clear to us at this moment. Rayleigh waves can be clearly observed for station pairs at the distance of 80 km and larger but are contaminated by the near zero time phase at shorter station spacing. Rayleigh wave phase velocities at periods of 4 to 15 s will be produced from the ambient noise data. Using regional and teleseismic earthquakes, we expect to obtain Rayleigh wave dispersions at periods from 15 to 50 s. The phase velocities from both datasets will be inverted for crustal thickness and shear-wave structure beneath the Pakistan Himalayas.

  19. A survey of models for the prediction of ambient ocean noise: Circa 1995

    Energy Technology Data Exchange (ETDEWEB)

    Doolittle, R.

    1996-01-01

    The state of the art of model development for application to computer studies of undersea search systems utilizing acoustics is surveyed in this document. Due to the demands for surveillance of submarines operating in ocean basins, the development of noise models for application in deep oceans is fairly advanced and somewhat generic. This is due to the deep sound channel, discovered during World War II, which when present allows for long-range sound propagation with little or no interaction with the bottom. Exceptions to this channel, also well understood, are found in both the high latitudes where the sound is upward refracting and in tropical ocean areas with downward refracting sound transmission. The controlling parameter is the sound speed as a function of depth within the ocean, the sound speed profile. When independent of range, this profile may be converted to a noise-versus-depth profile with well-validated consequences for deep-ocean ambient noise. When considering ocean areas of shallow water, the littoral regions, the idea of a genenic ocean channel advisedly is abandoned. The locally unique nature of both the noise production mechanisms and of the channel carrying the sound, obviates the generic treatment. Nevertheless, idealizations of this case exist and promote the understanding if not the exact predictability of the statistics of shallow water ambient noise. Some examples of these models are given in this document.

  20. Retrieval of Moho-reflected shear wave arrivals from ambient seismic noise

    OpenAIRE

    Zhan, Zhongwen; Ni, Sidao; Helmberger, Don V.; Clayton, Robert W.

    2010-01-01

    Theoretical studies on ambient seismic noise (ASN) predict that complete Green's function between seismic stations can be retrieved from cross correlation. However, only fundamental mode surface waves emerge in most studies involving real data. Here we show that Moho-reflected body wave (SmS) and its multiples can be identified with ASN for station pairs near their critical distances in the short period band (1–5 s). We also show that an uneven distribution of noise sources, such as mining ac...

  1. pSIN: A scalable, Parallel algorithm for Seismic INterferometry of large-N ambient-noise data

    Science.gov (United States)

    Chen, Po; Taylor, Nicholas J.; Dueker, Ken G.; Keifer, Ian S.; Wilson, Andra K.; McGuffy, Casey L.; Novitsky, Christopher G.; Spears, Alec J.; Holbrook, W. Steven

    2016-08-01

    Seismic interferometry is a technique for extracting deterministic signals (i.e., ambient-noise Green's functions) from recordings of ambient-noise wavefields through cross-correlation and other related signal processing techniques. The extracted ambient-noise Green's functions can be used in ambient-noise tomography for constructing seismic structure models of the Earth's interior. The amount of calculations involved in the seismic interferometry procedure can be significant, especially for ambient-noise datasets collected by large seismic sensor arrays (i.e., "large-N" data). We present an efficient parallel algorithm, named pSIN (Parallel Seismic INterferometry), for solving seismic interferometry problems on conventional distributed-memory computer clusters. The design of the algorithm is based on a two-dimensional partition of the ambient-noise data recorded by a seismic sensor array. We pay special attention to the balance of the computational load, inter-process communication overhead and memory usage across all MPI processes and we minimize the total number of I/O operations. We have tested the algorithm using a real ambient-noise dataset and obtained a significant amount of savings in processing time. Scaling tests have shown excellent strong scalability from 80 cores to over 2000 cores.

  2. Waveform modeling and inversion of ambient noise cross-correlation functions in a coastal ocean environment.

    Science.gov (United States)

    Zang, Xiaoqin; Brown, Michael G; Godin, Oleg A

    2015-09-01

    Theoretical studies have shown that cross-correlation functions (CFs) of time series of ambient noise measured at two locations yield approximations to the Green's functions (GFs) that describe propagation between those locations. Specifically, CFs are estimates of weighted GFs. In this paper, it is demonstrated that measured CFs in the 20-70 Hz band can be accurately modeled as weighted GFs using ambient noise data collected in the Florida Straits at ∼100 m depth with horizontal separations of 5 and 10 km. Two weighting functions are employed. These account for (1) the dipole radiation pattern produced by a near-surface source, and (2) coherence loss of surface-reflecting energy in time-averaged CFs resulting from tidal fluctuations. After describing the relationship between CFs and GFs, the inverse problem is considered and is shown to result in an environmental model for which agreement between computed and simulated CFs is good.

  3. Explore Seismic Velocity Change Associated with the 2010 Kaohsiung Earthquake by Ambient Noise Tomography

    Science.gov (United States)

    Ku, Chin-Shang; Wu, Yih-Min; Huang, Bor-Shouh; Huang, Win-Gee; Liu, Chun-Chi

    2016-04-01

    A ML 6.4 earthquake occurred on 4 March 2010 in Kaohsiung, the southern part of Taiwan, this shallow earthquake is the largest one of that area in the past few years. Some damages occurred on buildings and bridges after the earthquake, obvious surface deformation up to few cm was observed and the transportation including road and train traffic was also affected near the source area. Some studies about monitoring the velocity change induced by the big earthquake were carried out recently, most of studies used cross-correlation of the ambient noise-based method and indicated velocity drop was observed immediately after the big earthquake. However, this method is not able to constrain the depth of velocity change, and need to assume a homogeneous seismic velocity change during the earthquake. In this study, we selected 25 broadband seismic stations in the southern Taiwan and time period is from 2009/03 to 2011/03. Then we explored the velocity change associated with the 2010 Kaohsiung earthquake by applying ambient noise tomography (ANT) method. ANT is a way of using interferometry to image subsurface seismic velocity variations by using surface wave dispersions extracted from the ambient noise cross-correlation of seismic station-pairs, then the 2-D group velocity map with different periods could be extracted. Compare to ambient noise-based cross-correlation analysis, we estimated sensitivity kernel of dispersion curves and converted 2-D group velocity map from "with the period" to "with the depth" to have more constraints on the depth of velocity change. By subtracting shear velocity between "before" and "after" the earthquake, we could explore velocity change associated with the earthquake. Our result shows velocity reduction about 5-10% around the focal depth after the 2010 Kaohsiung earthquake and the post-seismic velocity recovery was observed with time period increasing, which may suggest a healing process of damaged rocks.

  4. 4-D imaging and monitoring of the Solfatara crater (Italy) by ambient noise tomography

    Science.gov (United States)

    Pilz, Marco; Parolai, Stefano; Woith, Heiko; Gresse, Marceau; Vandemeulebrouck, Jean

    2016-04-01

    Imaging shallow subsurface structures and monitoring related temporal variations are two of the main tasks for modern geosciences and seismology. Although many observations have reported temporal velocity changes, e.g., in volcanic areas and on landslides, new methods based on passive sources like ambient seismic noise can provide accurate spatially and temporally resolved information on the velocity structure and on velocity changes. The success of these passive applications is explained by the fact that these methods are based on surface waves which are always present in the ambient seismic noise wave field because they are excited preferentially by superficial sources. Such surface waves can easily be extracted because they dominate the Greeńs function between receivers located at the surface. For real-time monitoring of the shallow velocity structure of the Solfatara crater, one of the forty volcanoes in the Campi Flegrei area characterized by an intense hydrothermal activity due to the interaction of deep convection and meteoric water, we have installed a dense network of 50 seismological sensing units covering the whole surface area in the framework of the European project MED-SUV (The MED-SUV project has received funding from the European Union Seventh Framework Programme FP7 under Grant agreement no 308665). Continuous recordings of the ambient seismic noise over several days as well as signals of an active vibroseis source have been used. Based on a weighted inversion procedure for 3D-passive imaging using ambient noise cross-correlations of both Rayleigh and Love waves, we will present a high-resolution shear-wave velocity model of the structure beneath the Solfatara crater and its temporal changes. Results of seismic tomography are compared with a 3-D electrical resistivity model and CO2 flux map.

  5. On the Use of Infrasonic Ambient Noise in Imaging the Atmosphere

    Science.gov (United States)

    Evers, L. G.; Fricke, J.; Smets, P. S. M.; Assink, J. D.

    2015-12-01

    To retrieve information on the wind and temperature in the (upper) atmosphere, determinsitic transient signals, like those from volcanoes, can be used. Both the traveltime and the slowness of the signals can be translated to variations in the wind and temperature structure along the source-receiver trajectory. In such a case, ground-truth about the source location and sometimes orgin time are necessary to restrict the analysis. However, sources with such a ground-truth are limited to certain geographical locations and have a sparse temporal availability. It is therefore attractive to use the ambient noise field, which is continuously present from a variety of directions. In theory, the cross correlation of the ambient noise field between two receivers should reveal the acoustic lag time between these receivers. With a known distance between the receivers, this lag time can be translated to the acoustic velocity which in turn is a function of the wind and temperature. In this presentation, the theory and results of this so-called ambient noise interferometry will be shown.

  6. Preliminary Ambient Noise and Seismic Interferometry Analysis of the Laguna del Maule Volcanic Field, Chile

    Science.gov (United States)

    Wespestad, C.; Thurber, C. H.; Bennington, N. L.; Zeng, X.; Cardona, C.; Keranen, K. M.; Singer, B. S.

    2015-12-01

    Laguna del Maule Volcanic Field is a large, restless, youthful rhyolitic system in the Southern Andes of Chile. We present a preliminary examination of ambient noise data at this site from 12 University of Wisconsin and 6 OVDAS (Southern Andean Volcano Observatory) broadband seismometers for a 3 month period. Ambient noise tomography seeks to correlate pairs of stations, with one station acting as a virtual source and the other a receiver, generating empirical Green's functions between each pair. The noise correlation functions (NCFs) were computed for day-long and hour-long windows, then the final NCFs were obtained from stacking each time window set. The hour-long NCFs converged more rapidly, so this time window was chosen for use in later stages. This study used phase weighted stacking of the NCFs instead of linear stacking in order to achieve a better signal to noise ratio (SNR), although linearly stacked Green's functions were also created to confirm the improvement. Phase weighted stacking can detect signals with weak amplitudes much more clearly than linear stacking by finding coherence of signals in multiple frequency bins and down-weighting the importance of amplitude for correlation (Schimmel and Gallart, 2007). The Frequency-Time Analysis Technique was utilized to measure group velocity, and initial results show it to be about 2 km/s on average. Fluctuations of the average velocity between different station pairs across this dense array will provide a preliminary indication of the location and size of the magma system. This study also applied seismic interferometry using ambient noise to determine temporal changes in seismic velocity occurring at Laguna del Maule. Initial results show temporal changes in seismic velocity correlated to seasonal changes in the hydrologic cycle (rain, snow pack, snow melt, etc.). Current work focuses on identifying changes in seismic velocity associated with ongoing volcanic processes.

  7. Ocean acoustic remote sensing using ambient noise: results from the Florida Straits

    Science.gov (United States)

    Brown, M. G.; Godin, O. A.; Zang, X.; Ball, J. S.; Zabotin, N. A.; Zabotina, L. Y.; Williams, N. J.

    2016-07-01

    Noise interferometry is the process by which approximations to acoustic Green's functions, which describe sound propagation between two locations, are estimated by cross-correlating time series of ambient noise measured at those locations. Noise-interferometry-based approximations to Green's functions can be used as the basis for a variety of inversion algorithms, thereby providing a purely passive alternative to active-source ocean acoustic remote sensing. In this paper we give an overview of results from noise interferometry experiments conducted in the Florida Straits at 100 m depth in December 2012, and at 600 m depth in September/October 2013. Under good conditions for noise interferometry, estimates of cross-correlation functions are shown to allow one to perform advanced phase-coherent signal processing techniques to perform waveform inversions, estimate currents by exploiting non-reciprocity, perform time-reversal/back-propagation calculations and investigate modal dispersion using time-warping techniques. Conditions which are favourable for noise interferometry are identified and discussed.

  8. Ambient awareness: From random noise to digital closeness in online social networks

    Science.gov (United States)

    Levordashka, Ana; Utz, Sonja

    2016-01-01

    Ambient awareness refers to the awareness social media users develop of their online network in result of being constantly exposed to social information, such as microblogging updates. Although each individual bit of information can seem like random noise, their incessant reception can amass to a coherent representation of social others. Despite its growing popularity and important implications for social media research, ambient awareness on public social media has not been studied empirically. We provide evidence for the occurrence of ambient awareness and examine key questions related to its content and functions. A diverse sample of participants reported experiencing awareness, both as a general feeling towards their network as a whole, and as knowledge of individual members of the network, whom they had not met in real life. Our results indicate that ambient awareness can develop peripherally, from fragmented information and in the relative absence of extensive one-to-one communication. We report the effects of demographics, media use, and network variables and discuss the implications of ambient awareness for relational and informational processes online. PMID:27375343

  9. Characterizing waveform uncertainty due to ambient noise for the Global Seismic Network

    Science.gov (United States)

    Guandique, J. A.; Burdick, S.; Lekic, V.

    2015-12-01

    Ambient seismic noise is the vibration present on seismograms not due by any earthquake or discrete source. It can be caused by trees swaying in the wind or trucks rumbling on the freeway, but the main source of noise is the microseism caused by ocean waves. The frequency content and amplitude of seismic noise varies due to weather, season, and the location of a station, among other factors. Because noise affects recordings of earthquake waveforms, better understanding it could improve the detection of small earthquakes, reduce false positives in earthquake early warning, and quantify uncertainty in waveform-based studies In this study, we used two years of 3-component accelerograms from stations in the GSN. We eliminate days with major earthquakes, aggregate analysis by month, and calculate the mean power spectrum for each component and the transfer function between components. For each power spectrum, we determine the dominant frequency and amplitude of the primary (PM) and secondary (SM) microseisms which appear at periods of ~14s and ~7s, as well as any other prominent peaks. The cross-component terms show that noise recorded on different components cannot be treated as independent. Trends in coherence and phase delay suggest directionality in the noise and information about in which modes it propagates. Preliminary results show that the noise on island stations exhibits less monthly variability, and its PM peaks tend to be much weaker than the SM peaks. The continental stations show much less consistent behavior, with higher variability in the PM peaks between stations and higher frequency content during winter months. Stations that are further inland have smaller SM peaks compared to coastal stations, which are more similar to island stations. Using these spectra and cross-component results, we develop a method for generating realistic 3-component seismic noise and covariance matrices, which can be used across various seismic applications.

  10. Rayleigh Wave Tomography of Mid-Continent Rift (MCR) using Earthquake and Ambient Noise Data

    Science.gov (United States)

    Aleqabi, G. I.; Wiens, D.; Wysession, M. E.; Shen, W.; van der Lee, S.; Revenaugh, J.; Frederiksen, A. W.; Darbyshire, F. A.; Stein, S. A.; Jurdy, D. M.; Wolin, E.; Bollmann, T. A.

    2015-12-01

    The structure of the North American Mid-Continent Rift Zone (MCRZ) is examined using Rayleigh waves from teleseismic earthquakes and ambient seismic noise recorded by the Superior Province Rifting EarthScope Experiment (SPREE). Eighty-four broadband seismometers were deployed during 2011-2013 in Minnesota and Wisconsin, USA, and Ontario, CA, along three lines; two across the rift axis and the third along the rift axis. These stations, together with the EarthScope Transportable Array, provided excellent coverage of the MCRZ. The 1.1 Ga Mesoproterozoic failed rift consists of two arms, buried under post-rifting sedimentary formations that meet at Lake Superior. We compare two array-based tomography methods using teleseismic fundamental mode Rayleigh waves phase and amplitude measurements: the two-plane wave method (TPWM, Forsyth, 1998) and the automated surface wave phase velocity measuring system (ASWMS, Jin and Gaherty, 2015). Both array methods and the ambient noise method give relatively similar results showing low velocity zones extending along the MCRZ arms. The teleseismic Rayleigh wave results from 18 - 180 s period are combined with short period phase velocity results (period 8-30 s) obtained from ambient noise by cross correlation. Phase velocities from the methods are very similar at periods of 18-30 where results overlap; in this period range we use the average of the noise and teleseismic results. Finally the combined phase velocity curve is inverted using a Monte-Carlo inversion method at each geographic point in the model. The results show low velocities at shallow depths (5-10 km) that are the result of very deep sedimentary fill within the MCRZ. Deeper-seated low velocity regions may correspond to mafic underplating of the rift zone.

  11. Local Ambient Seismic Noise Survey in Dixie Valley, NV for Engineered Geothermal System Favorability Assessment

    Science.gov (United States)

    Tibuleac, I. M.; Iovenitti, J. L.; von Seggern, D. H.; Sainsbury, J.

    2013-12-01

    The primary objective of this study is to develop and test the seismic component of a calibrated exploration method that integrated geological, geophysical, and geochemical data to identify potential drilling targets for Engineered Geothermal Systems (EGS). In exploring for EGS sites, the selection criteria identified by the AltaRock Energy, Inc. (AltaRock) and University of Nevada, Reno teams are, in order of importance, (1) temperature greater than 200C at 1.5 km depth, (2) rock type at the depth of interest (porous rocks at 1-3 km); and (3) favorable stress regime (tensional environment). To improve spatial resolution, a dense seismic array (21 three-component, broadband sensors, with an overall array aperture of 45km) was installed in two deployments in Dixie Valley, NV, each deployment having a three-month duration Ambient seismic noise and signal were used to retrieve inter-station and same-station Green's Functions (GFs), to be used for subsurface imaging. We used ambient seismic noise interferometry to extract GFs from crosscorrelation of continuous records. An innovative aspect of the seismic work was estimating the receiver functions beneath the stations using noise auto-correlation which was used to image the substructure. We report results of applying the technique to estimate a P/S velocity model from the GF surface wave components and from the GF body-wave reflection component, retrieved from ambient noise and signal cross-correlation and auto-correlation beams. We interpret our results in terms of temperature, pressure and rock composition. The estimated seismic velocity model capability to infer temperature is statistically assessed, in combination with other geophysical technique results.

  12. 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

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

    International Nuclear Information System (INIS)

    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

  14. 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.

  15. 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.

  16. Tracking velocity changes from ambient noise and repeating airgun shots in Tenerife

    Science.gov (United States)

    Volk, M. F.; Bean, C. J.; Lokmer, I.; Perez, N. M.; Ibanez, J. M.

    2015-12-01

    Green's functions can be recovered through the cross correlation of ambient seismic noise. These Green's functions can be used to image the subsurface or for monitoring geological settings where we expect rapid seismic velocity changes (e.g. volcanoes, reservoirs). The criterion for the successful recovery of the Green's functions is that the wavefields used for the cross correlation are diffuse. This assumption is fulfilled if either the noise sources are uniformly distributed around the receivers or the scattering in the medium is high enough to mitigate any source directivity. The locations of the noise sources are usually unknown and they change with time. Therefore, apparent changes in seismic wave velocity can be observed which are caused by temporal and spatial changes in the noise source location.In order to investigate these apparent changes in the Green's functions we undertook an experiment in Tenerife. The experiment was running for 3 months. A small airgun, with exactly known source position, was used as an active source. It was shooting every 15 minutes and several seismic stations laterally and vertically distributed around the airgun recorded the active shots. Coincident to the active shots seismic noise was recorded. Therefore apparent velocity changes measured through the cross correlation of noise can be compared to velocity changes recovered from the repetitive shots. This gives us the opportunity to distinguish between apparent changes due to changes in the noise sources and real velocity changes in the medium. In addition barometric pressure, temperature, rain fall and humidity were recorded in order to avoid misinterpretation of the velocity changes caused by weather fluctuations.

  17. Effect of earthquakes on ambient noise surface wave tomography in upper-mantle studies

    Science.gov (United States)

    Yanovskaya, Tatiana; Koroleva, Tatiana; Lyskova, Eugenia

    2016-05-01

    Application of the ambient noise surface wave tomography method (ANT) for determination of the upper-mantle structure requires data on long-periodic noise (T > 40 s). The ANT technique implies that noise sources are distributed almost uniformly over the surface. This is practically true for short-periodic noise, however, it is not so in the case of long periods. In this paper we show that the main contribution to noise at long periods is caused by signals from earthquakes. In some cases, they may strongly distort noise cross-correlation. This leads to an incorrect determination of surface wave velocity dispersion curves. To minimize such a distortion we propose two means: (1) to use records of noise for the periods when there is no clustering of earthquakes, such as aftershocks of strong events; (2) to stack cross-correlation functions for a period of at least three years in order to achieve sufficient uniformity of earthquake locations. Validity of this approach is demonstrated by ANT results for Europe. Tomographic reconstruction of Rayleigh wave group velocities for 10-100 s measured along interstation paths was carried out in a central part of Western Europe where resolving power of the data was the highest. Locally averaged dispersion curves were inverted to vertical S-wave velocity sections in this area. The results correspond closely to known features of the structure of the region, namely: strong difference of the crust and upper-mantle structure at the opposite sides from the Tornquist-Teisseyre Line down to ˜ 250 km, penetration of high-velocity material of East European Platform lithosphere under Carpathians, as well as penetration of low-velocity asthenospheric layer from the Carpathian region towards the northeast.

  18. Frequency Content of Ambient Seismic Noise in North-Central Illinois

    Science.gov (United States)

    Higuera-Diaz, I. C.; Carpenter, P. J.

    2004-12-01

    High and low-frequency ground motion vibration measurements were made in DeKalb and Kane Counties, Illinois, to characterize different sources of seismic noise and determine directions and magnitude of motion produced by each source. The Seismic Analysis Code 2000 (SAC2000) was used to process seismic noise data recorded with a low-frequency digital system,, earthquake records downloaded from the WILBER Web site, and noise data recorded by an engineering seismograph with high-frequency geophones. Power-spectral density estimates were computed from an autocorrelation series in most cases. Using the power density spectra routine of SAC2000, selecting autocorrelation windows of 20 s for the low-frequency data and 2 s for the high-frequency data, we have found distinctive seismic noise peaks among the different sites, regardless of the background noise level. The earthquake low-frequency data showed a microseism peak at a frequency of 0.2 Hz for stations located in the Midwestern U.S. Microseism peak frequency did not decrease with increasing distance from Lake Michigan, suggesting the lake is not the primary source of the microseisms, which may be generated in ocean basins. Ambient ground motion recorded by the Northern Illinois University seismic station with a 2 Hz natural period seismometer exhibited peaks around 0.8 and 2.2 Hz. Ground motion from trains, traffic, air-conditioning units and water pumping equipment was recorded with an engineering seismograph. Vertical geophones of natural frequency 2, 8, and 50 Hz were used, as well as a 4.5 Hz horizontal geophone. Train noise exhibits strong peaks in the 5-10 Hz range, both for the vertical and horizontal geophones. Noise peaks at 25, 60, 90 and 115 Hz are probably related to traffic, electrical transformers, and air-conditioning units. Measurements made near a sewage treatment plant in DeKalb showed peaks at 10, 30, 93, and 109 Hz, probably related to pumping and mechanical equipment. Seismic noise collected

  19. High-resolution surface-wave tomography from ambient seismic noise.

    Science.gov (United States)

    Shapiro, Nikolai M; Campillo, Michel; Stehly, Laurent; Ritzwoller, Michael H

    2005-03-11

    Cross-correlation of 1 month of ambient seismic noise recorded at USArray stations in California yields hundreds of short-period surface-wave group-speed measurements on interstation paths. We used these measurements to construct tomographic images of the principal geological units of California, with low-speed anomalies corresponding to the main sedimentary basins and high-speed anomalies corresponding to the igneous cores of the major mountain ranges. This method can improve the resolution and fidelity of crustal images obtained from surface-wave analyses. PMID:15761151

  20. Detecting seasonal variations in seismic velocities within Los Angeles basin from correlations of ambient seismic noise.

    OpenAIRE

    Ueli, Meier; Brenguier, Florent; M. Shapiro, N.

    2010-01-01

    International audience We analyze 3 years of continuous seismic records from broadband stations of the Caltech Regional Seismic Network (CI) in vicinity of the Los Angeles basin. Using correlations of ambient seismic noise, relative velocity variations in the order of 0.1 % can be measured between all inter-station pairs. It is the first time that such an extensive study between 861 inter-station pairs over such a large area has been carried out. We perform these measurements using the 'st...

  1. Crustal structure of Mexico and surrounding regions from seismic ambient noise tomography

    OpenAIRE

    Gaite, Beatriz; Iglesias, Arturo; Villaseñor, Antonio; Herraiz Sarachaga, Miguel; Pacheco, Javier F.

    2012-01-01

    Using continuous seismic data from newly available broadband stations in Mexico and Central America we have obtained group and phase velocity maps of fundamental mode Rayleigh wave for the region. These new maps have been calculated for periods between 8 and 60 s from cross-correlations of seismic ambient noise between 100 broadband stations, and stacked for 30 months from 2006 to 2008. The tomographic inversion of the obtained dispersion measurements has been carried out on a 1°× 1° grid, re...

  2. Nonlinear Dynamics of an Ambient Noise Driven Array of Coupled Graphene Nanostructured Devices for Energy Harvesting

    Directory of Open Access Journals (Sweden)

    El Aroudi A.

    2014-01-01

    Full Text Available Nonlinearities have been shown to play an important role in increasing the extracted energy of energy harvesting devices at the macro and micro scales. Vibration-based energy harvesting on the nano scale has also received attention. In this paper, we characterize the nonlinear dynamical behavior of an array of three coupled strained nanostructured graphene for its potential use in energy harvesting applications. The array is formed by three compressed vibrating membrane graphene sheet subject to external vibrational noise excitation. We present the continuous time dynamical model of the system in the form of a double-well three degree of freedom system. Random vibrations are considered as the main ambient energy source for the system and its performances in terms of the probability density function, RMS or amplitude value of the position, FFT spectra and state plane trajectories are presented in the steady state non-equilibrium regime when the noise level is considered as a control parameter.

  3. Effects of noise from non-traffic-related ambient sources on sleep: Review of the literature of 1990-2010

    OpenAIRE

    Sarah Omlin; Bauer, Georg F.; Mark Brink

    2011-01-01

    This article reviews the literature about the effects of specific non-traffic-related ambient noise sources on sleep that appeared in the last two decades. Although everybody is faced with noise of non-traffic and non-industry origin (e.g. sounds made by neighbors, talk, laughter, music, slamming doors, structural equipment, ventilation, heat pumps, noise from animals, barking dogs, outdoor events etc.), little scientific knowledge exists about its effects on sleep. The findings of the presen...

  4. New developments in ambient noise analysis to characterise the seismic response of landslide prone slopes

    Directory of Open Access Journals (Sweden)

    V. Del Gaudio

    2013-04-01

    Full Text Available We report on new developments in the application of ambient noise analysis applied to investigate the dynamic response of landslide prone slopes to seismic shaking with special attention to the directional resonance phenomena recognised in previous studies. Investigations relying on the calculation of horizontal-to-vertical noise spectral ratio (HVNR were carried out in the area of Caramanico Terme (central Italy where an ongoing accelerometer monitoring on slopes with different characteristics offers the possibility of validation of HVNR analysis. The noise measurements, carried out in different times to test the result repeatability, revealed that sites affected by response directivity persistently show major peaks with a common orientation consistent with the resonance direction inferred from accelerometer data. At sites where directivity is absent, the HVNR peaks do not generally show a preferential orientation, with rare exceptions that could be linked to the presence of temporarily active sources of polarised noise. The observed spectral ratio amplitude variations can be related to temporal changes in site conditions, which can hinder the recognition of main resonance frequencies. Therefore, it is recommended to conduct simultaneous measurements at nearby sites within the same study area and to repeat measurements at different times in order to distinguish significant systematic polarisation caused by site specific response directivity from polarisation controlled by properties of noise sources. Furthermore, an analysis of persistence in noise recordings of signals with systematic directivity showed that only a~portion of recordings contains wave trains having a clear polarisation representative of site directional resonance. Thus a careful selection of signals for HVNR analysis is needed for a correct characterisation of site directional properties.

  5. 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 music decreases propofol requirements of both Lebanese and American patients who undergo urological surgery under spinal anesthesia. PMID:15845676

  6. Ambient Noise and Teleseismic Signals Recorded by Ocean-Bottom Seismometers Offshore Eastern Taiwan

    Directory of Open Access Journals (Sweden)

    Ching-Ren Lin

    2010-01-01

    Full Text Available Broadband records from ocean-bottom seismometers deployed in the Okinawa trough and the Huatung basin were analyzed to provide seafloor noise characteristics and the detection thresholds for teleseismic body and surface waves. Ambient noise levels on the horizontal components are 10 - 40 dB higher than on the vertical component, with the sensor seated on the surface of the sediment. On the vertical components, infragravity waves are 10 - 30 dB more energetic at the shallower Okinawa trough sites (≤ 2000 m depth than at the deeper Huatung basin site (~4700 m. From 0.03 to 0.2 Hz, the Huatung basin noise levels are comparable to that of the broadband stations in Taiwan on a quiet day. The microseism peaks (~0.2 - 0.5 Hz of OBSs reach or exceed the high noise model of continental stations. At regional distances Mw 6.5 is required for recording prominent Rayleigh waves if the source radiation is unfavorable, but 6.2 is sufficient for a favorable focal mecha¬nism.mecha¬nism. Several tens to over one hundred high-fidelity P, Pdiff and PKP waveforms have been recorded per year by OBSs at high corner frequency of 0.1 Hz with a minimum Mw 5.3 - 6.0. The number of recording drops to less than 5 per year at 1 Hz with Mw ≥ 6.4 and distances less than _

  7. Documenting and Assessing Dolphin Calls and Ambient and Anthropogenic Noise Levels via PAM and a SPL Meter.

    Science.gov (United States)

    Dudzinski, Kathleen M; Melillo-Sweeting, Kelly; Gregg, Justin D

    2016-01-01

    Song Meter SM2M marine recorders were deployed to document dolphin calls and ambient and anthropogenic noise. Recordings from Bimini were split into 2-h segments; no segment was without dolphin calls. At Dolphin Encounters, average noise levels ranged from 110 to 125 dB; the highest source level was 147.98 dB re 1 μPa at 1 m. Average ambient-noise levels documented at 4 sites in Guam were below 118 dB re 1 μPa at 1 m. These data were compared with values from a custom-built sound pressure level (SPL) meter and confirm that the SM2M recorder is a useful tool for assessing animal calls and ambient and anthropogenic noise levels.

  8. Documenting and Assessing Dolphin Calls and Ambient and Anthropogenic Noise Levels via PAM and a SPL Meter.

    Science.gov (United States)

    Dudzinski, Kathleen M; Melillo-Sweeting, Kelly; Gregg, Justin D

    2016-01-01

    Song Meter SM2M marine recorders were deployed to document dolphin calls and ambient and anthropogenic noise. Recordings from Bimini were split into 2-h segments; no segment was without dolphin calls. At Dolphin Encounters, average noise levels ranged from 110 to 125 dB; the highest source level was 147.98 dB re 1 μPa at 1 m. Average ambient-noise levels documented at 4 sites in Guam were below 118 dB re 1 μPa at 1 m. These data were compared with values from a custom-built sound pressure level (SPL) meter and confirm that the SM2M recorder is a useful tool for assessing animal calls and ambient and anthropogenic noise levels. PMID:26610966

  9. Ambient noise tomography with non-uniform noise sources and low aperture networks: case study of deep geothermal reservoirs in northern Alsace, France

    Science.gov (United States)

    Lehujeur, Maximilien; Vergne, Jérôme; Maggi, Alessia; Schmittbuhl, Jean

    2016-10-01

    We developed and applied a method for ambient noise surface wave tomography that can deal with noise cross-correlation functions governed to first order by a non-uniform distribution of the ambient seismic noise sources. The method inverts the azimuthal distribution of noise sources that are assumed to be far from the network, together with the spatial variations of the phase and group velocities on an optimized irregular grid. Direct modeling of the two-sided noise correlation functions avoids dispersion curve picking on every station pair and minimizes analyst intervention. The method involves station pairs spaced by distances down to a fraction of a wavelength, thereby bringing additional information for tomography. After validating the method on synthetic data, we applied it to a set of long-term continuous waveforms acquired around the geothermal sites at Soultz-sous-Forêts and Rittershoffen (Northern Alsace, France). For networks with limited aperture, we show that taking the azimuthal variations of the noise energy into account has significant impact on the surface wave dispersion maps. We obtained regional phase and group velocity models in the 1-7 s period range, which is sensitive to the structures encompassing the geothermal reservoirs. The ambient noise in our dataset originates from two main directions, the northern Atlantic Ocean and the Mediterranean Sea, and is dominated by the first Rayleigh wave overtone in the 2 - 5 s period range.

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

    Science.gov (United States)

    Szanyi, Gyöngyvér; Gráczer, Zoltán; Győri, Erzsébet; Kaláb, Zdeněk; Lednická, Markéta

    2016-05-01

    High loess banks along the right side of the Danube in Hungary are potential subjects of landslides. Small scale ambient seismic noise tomography was used at the Dunaszekcső high bank. The aim of the study was to map near surface velocity anomalies since we assume that the formation of tension cracks—which precede landslides—are represented by low velocities. Mapping Rayleigh wave group velocity distribution can help to image intact and creviced areas and identify the most vulnerable sections. The study area lies at the top of the Castle Hill of Dunaszekcső, which was named after Castellum Lugio, a fortress of Roman origin. The presently active head scarp was formed in April 2011, and our study area was chosen to be at its surroundings. Cross-correlation functions of ambient noise recordings were used to retrieve the dispersion curves, which served as the input of the group velocity tomography. Phase cross-correlation and time-frequency phase weighted stacking was applied to calculate the cross-correlation functions. The average Rayleigh wave group velocity at the high loess bank was found to be 171 ms^{-1} . The group velocity map at a 0.1 s period revealed a low-velocity region, whose location coincides with a highly creviced area, where slope failure takes place along a several meter wide territory. Another low velocity region was found, which might indicate a previously unknown loosened domain. The highest velocities were observed at the supposed remnants of Castellum Lugio.

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

    Science.gov (United States)

    Szanyi, Gyöngyvér; Gráczer, Zoltán; Győri, Erzsébet; Kaláb, Zdeněk; Lednická, Markéta

    2016-08-01

    Loess high banks along the right side of the Danube in Hungary are potential subjects of landslides. Small scale ambient seismic noise tomography was used at the Dunaszekcső high bank. The aim of the study was to map near surface velocity anomalies since we assume that the formation of tension cracks—which precede landslides—are represented by low velocities. Mapping Rayleigh wave group velocity distribution can help to image intact and creviced areas and identify the most vulnerable sections. The study area lies at the top of the Castle Hill of Dunaszekcső, which was named after Castellum Lugio, a fortress of Roman origin. The presently active head scarp was formed in April 2011, and our study area was chosen to be at its surroundings. Cross-correlation functions of ambient noise recordings were used to retrieve the dispersion curves, which served as the input of the group velocity tomography. Phase cross-correlation and time-frequency phase weighted stacking was applied to calculate the cross-correlation functions. The average Rayleigh wave group velocity at the loess high bank was found to be 171 ms^{-1}. The group velocity map at a 0.1 s period revealed a low-velocity region, whose location coincides with a highly creviced area, where slope failure takes place along a several meter wide territory. Another low velocity region was found, which might indicate a previously unknown loosened domain. The highest velocities were observed at the supposed remnants of Castellum Lugio.

  12. Correction of phase velocity bias caused by strong directional noise sources in high-frequency ambient noise tomography: a case study in Karamay, China

    Science.gov (United States)

    Wang, Kai; Luo, Yinhe; Yang, Yingjie

    2016-05-01

    We collect two months of ambient noise data recorded by 35 broad-band seismic stations in a 9 × 11 km area (1-3 km station interval) near Karamay, China, and do cross-correlation of noise data between all station pairs. Array beamforming analysis of the ambient noise data shows that ambient noise sources are unevenly distributed and the most energetic ambient noise mainly comes from azimuths of 40°-70°. As a consequence of the strong directional noise sources, surface wave components of the cross-correlations at 1-5 Hz show clearly azimuthal dependence, and direct dispersion measurements from cross-correlations are strongly biased by the dominant noise energy. This bias renders that the dispersion measurements from cross-correlations do not accurately reflect the interstation velocities of surface waves propagating directly from one station to the other, that is, the cross-correlation functions do not retrieve empirical Green's functions accurately. To correct the bias caused by unevenly distributed noise sources, we adopt an iterative inversion procedure. The iterative inversion procedure, based on plane-wave modeling, includes three steps: (1) surface wave tomography, (2) estimation of ambient noise energy and biases and (3) phase velocities correction. First, we use synthesized data to test the efficiency and stability of the iterative procedure for both homogeneous and heterogeneous media. The testing results show that: (1) the amplitudes of phase velocity bias caused by directional noise sources are significant, reaching ˜2 and ˜10 per cent for homogeneous and heterogeneous media, respectively; (2) phase velocity bias can be corrected by the iterative inversion procedure and the convergence of inversion depends on the starting phase velocity map and the complexity of the media. By applying the iterative approach to the real data in Karamay, we further show that phase velocity maps converge after 10 iterations and the phase velocity maps obtained using

  13. Ambient seismic noise tomography of SW Iberia integrating seafloor- and land-based data

    Science.gov (United States)

    Corela, Carlos; Silveira, Graça; Matias, Luís; Schimmel, Martin; Geissler, Wolfram

    2016-04-01

    We used ambient seismic noise recorded by 24 broadband ocean bottom seismometers (OBS-BB) deployed in in the Gulf of Cadiz during the EC funded NEAREST project and seven broadband land stations located in the South of Portugal to image the sedimentary and crustal structure beneath the Eastern Atlantic and SW Iberia. We computed ambient noise cross-correlations to obtain empirical Green's functions (EGFs) between all station pairs, and using both sort of sensors, namely seismometers and hydrophones. Despite the great difference between the crustal structure below beneath OBSs and land stations and the recording conditions, we were able to compute high signal-to-noise ratio EGFs, by applying a linear cross-correlation with a running absolute mean average time normalization, followed by a time-frequency phase weighted stack. Dispersion analysis was then applied to the EGFs, between 4 and 20s period. The obtained 395 reliable group velocity dispersion curves, between all station pairs, allowed mapping the lateral variation of Rayleigh wave group velocities, as a function of period. Finally, dispersion curves extracted from each cell of the 2D group velocity maps were inverted, as a function of depth, to obtain the 3D distribution of the shear-wave velocities. The 3-D shear wave velocity model, computed from joint inversion of OBS and land stations data allowed to estimate the thickness of sediments and crust and the Moho depth. Although, we could perceive the impact of the spatial gap between OBSs and land stations, our model displays a good correlation with the main geological features. The main results on the sedimentary layer thickness and on the Moho depth are in agreement with the model proposed by other studies using observations from multi-beam bathymetry and seismic profiling, thus confirming that, not only that ambient noise tomography is a valuable tool to image oceanic domains, but also that we can integrate seafloor- and land-based stations. Publication

  14. Effects of noise from non-traffic-related ambient sources on sleep: Review of the literature of 1990-2010

    Directory of Open Access Journals (Sweden)

    Sarah Omlin

    2011-01-01

    Full Text Available This article reviews the literature about the effects of specific non-traffic-related ambient noise sources on sleep that appeared in the last two decades. Although everybody is faced with noise of non-traffic and non-industry origin (e.g. sounds made by neighbors, talk, laughter, music, slamming doors, structural equipment, ventilation, heat pumps, noise from animals, barking dogs, outdoor events etc., little scientific knowledge exists about its effects on sleep. The findings of the present extensive literature search and review are as follows: Only a small number of surveys, laboratory and field studies about mainly neighborhood, leisure and animal noise have been carried out. Most of them indicate that ambient noise has some effect on human sleep. However, a quantitative meta-analysis and comparison is not possible due to the small number of studies available and at times large differences in quality.

  15. Effects of noise from non-traffic-related ambient sources on sleep: review of the literature of 1990-2010.

    Science.gov (United States)

    Omlin, Sarah; Bauer, Georg F; Brink, Mark

    2011-01-01

    This article reviews the literature about the effects of specific non-traffic-related ambient noise sources on sleep that appeared in the last two decades. Although everybody is faced with noise of non-traffic and non-industry origin (e.g. sounds made by neighbors, talk, laughter, music, slamming doors, structural equipment, ventilation, heat pumps, noise from animals, barking dogs, outdoor events etc.), little scientific knowledge exists about its effects on sleep. The findings of the present extensive literature search and review are as follows: Only a small number of surveys, laboratory and field studies about mainly neighborhood, leisure and animal noise have been carried out. Most of them indicate that ambient noise has some effect on human sleep. However, a quantitative meta-analysis and comparison is not possible due to the small number of studies available and at times large differences in quality. PMID:21768734

  16. Ice berg cracking events as identified from underwater ambient noise measurements in the shallow waters of Ny-Alesund, Arctic

    Science.gov (United States)

    Ashokan, M.; Latha, G.; Thirunavukkarasu, A.; Raguraman, G.; Venkatesan, R.

    2016-06-01

    This paper presents the work carried out on the analysis of preliminary underwater ambient noise measurements in the shallow waters of Kongsfjorden fjord, Arctic in the summer season, in which the ice berg cracking noise is identified. In the summer period, the melting of ice cover is fast and hence the ice bergs are free to move and float in the ocean. Underwater ambient noise has been acquired in the Kongsfjorden fjord, Arctic sea on 19th July 2015 at 5 m water depth, where the ocean depth is 50 m. Due to the tensile cracks at the surface of the sea ice by thermal expansion, ice berg calving and bobbing occurred near the experiment site. Analysis of power spectra shows that ice berg calving noise falls in the frequency band 100 Hz-500 Hz and the ice berg bobbing noise falls in the frequency band 200 Hz-400 Hz.

  17. Optimization of Ambient Noise Cross-Correlation Imaging Across Large Dense Array

    Science.gov (United States)

    Sufri, O.; Xie, Y.; Lin, F. C.; Song, W.

    2015-12-01

    Ambient Noise Tomography is currently one of the most studied topics of seismology. It gives possibility of studying physical properties of rocks from the depths of subsurface to the upper mantle depths using recorded noise sources. A network of new seismic sensors, which are capable of recording continuous seismic noise and doing the processing at the same time on-site, could help to assess possible risk of volcanic activity on a volcano and help to understand the changes in physical properties of a fault before and after an earthquake occurs. This new seismic sensor technology could also be used in oil and gas industry to figure out depletion rate of a reservoir and help to improve velocity models for obtaining better seismic reflection cross-sections. Our recent NSF funded project is bringing seismologists, signal processors, and computer scientists together to develop a new ambient noise seismic imaging system which could record continuous seismic noise and process it on-site and send Green's functions and/or tomography images to the network. Such an imaging system requires optimum amount of sensors, sensor communication, and processing of the recorded data. In order to solve these problems, we first started working on the problem of optimum amount of sensors and the communication between these sensors by using small aperture dense network called Sweetwater Array, deployed by Nodal Seismic in 2014. We downloaded ~17 day of continuous data from 2268 one-component stations between March 30-April 16 2015 from IRIS DMC and performed cross-correlation to determine the lag times between station pairs. The lag times were then entered in matrix form. Our goal is to selecting random lag time values in the matrix and assuming all other elements of the matrix either missing or unknown and performing matrix completion technique to find out how close the results from matrix completion technique would be close to the real calculated values. This would give us better idea

  18. 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

  19. Seismic tomography and ambient noise reflection interferometry on Reykjanes, SW Iceland

    Science.gov (United States)

    Jousset, Philippe; Verdel, Arie; Ágústsson, Kristján; Blanck, Hanna; Franke, Steven; Metz, Malte; Ryberg, Trond; Weemstra, Cornelius; Hersir, Gylfi; Bruhn, David

    2016-04-01

    Recent advances in volcano-seismology and seismic noise interferometry have introduced new processing techniques for assessing subsurface structures and controls on fluid flow in geothermal systems. We present tomographic results obtained from seismic data recorded around geothermal reservoirs located both on-land Reykjanes, SW-Iceland and offshore along Reykjanes Ridge. We gathered records from a network of 234 seismic stations (including 24 Ocean Bottom Seismometers) deployed between April 2014 and August 2015. In order to determine the orientation of the OBS stations, we used Rayleigh waves planar particle motions from large magnitude earthquakes. This method proved suitable using the on-land stations: orientations determined using this method with the orientations measured using a giro-compass agreed. We obtain 3D velocity images from two fundamentally different tomography methods. First, we used local earthquakes to perform travel time tomography. The processing includes first arrival picking of P- and S- phases using an automatic detection and picking technique based on Akaike Information Criteria. We locate earthquakes by using a non-linear localization technique, as a priori information for deriving a 1D velocity model. We then computed 3D velocity models of velocities by joint inversion of each earthquake's location and lateral velocity anomalies with respect to the 1D model. Our models confirms previous models obtained in the area, with enhanced details. Second, we performed ambient noise cross-correlation techniques in order to derive an S velocity model, especially where earthquakes did not occur. Cross-correlation techniques involve the computation of cross- correlation between seismic records, from which Green's functions are estimated. Surface wave inversion of the Green's functions allows derivation of an S wave velocity model. Noise correlation theory furthermore shows that zero-offset P-wave reflectivity at selected station locations can be

  20. Crustal velocity structure of Central and Eastern Turkey from ambient noise tomography

    Science.gov (United States)

    Warren, Linda M.; Beck, Susan L.; Biryol, C. Berk; Zandt, George; Özacar, A. Arda; Yang, Yingjie

    2013-09-01

    In eastern Turkey, the ongoing convergence of the Arabian and African plates with Eurasia has resulted in the westward extrusion of the Anatolian Plate. To better understand the current state and the tectonic history of this region, we image crust and uppermost mantle structure with ambient noise tomography. Our study area extends from longitudes of 32° to 44°E. We use continuous data from two temporary seismic deployments, our 2006-2008 North Anatolian Fault Passive Seismic Experiment and the 1999-2001 Eastern Turkey Seismic Experiment, as well as from additional seismographs in the region. We compute daily cross-correlations of noise records between all station pairs and stack them over the entire time period for which they are available, as well as in seasonal subsets, to obtain interstation empirical Green's functions. After selecting interstation cross-correlations with high signal-to-noise ratios and measuring interstation phase velocities, we compute phase velocity maps at periods ranging from 8 to 40 s. At all periods, the phase velocity maps are similar for winter and summer subsets of the data, indicating that seasonal variations in noise sources do not bias our results. Across the study area, we invert the phase velocity estimates for shear velocity as a function of depth. The shear velocity model, which extends to 50 km depth, highlights tectonic features apparent at the surface: the Eastern Anatolian Plateau is a prominent low-velocity anomaly whereas the Kirşehir Massif has relatively fast velocities. There is a large velocity jump across the Inner Tauride Suture/Central Anataolian Fault Zone throughout the crust whereas the North Anatolian Fault does not have a consistent signature. In addition, in the southeastern part of our study area, we image a high velocity region below 20 km depth which may be the northern tip of the underthrusting Arabian Plate.

  1. Seismic Tomography Around the Eastern Edge of the Alps From Ambient-Noise-Based Rayleigh Waves

    Science.gov (United States)

    Zigone, Dimitri; Fuchs, Florian; Kolinsky, Petr; Gröschl, Gidera; Apoloner, Maria-Theresia; Qorbani, Ehsan; Schippkus, Sven; Löberich, Eric; Bokelmann, Götz; AlpArray Working Group

    2016-04-01

    Inspecting ambient noise Green's functions is an excellent tool for monitoring the quality of seismic data, and for swiftly detecting changes in the configuration of a seismological station. Those Green's functions readily provide stable information about structural variations near the Earth's surface. We apply the technique to a network consisting of about 40 broadband stations in the area of the Easternmost Alps, in particular those operated by the University of Vienna (AlpArrayAustria) and the Vienna University of Technology. Those data are used to estimate Green's functions between station pairs; the Green's function consist mainly of surface waves, and we use them to investigate crustal structure near the Eastern edge of the Alps. To obtain better signal-to-noise ratios in the noise correlation functions, we adopt a procedure using short time windows (2 hr). Energy tests are performed on the data to remove effects of transient sources and instrumental problems. The resulting 9-component correlation tensor is used to make travel time measurements on the vertical, radial and transverse components. Those measurements can be used to evaluate dispersion using frequency-time analysis for periods between 5-30 seconds. After rejecting paths without sufficient signal-to-noise ratio, we invert the velocity measurements using the Barmin et al. (2001) approach on a 10 km grid size. The obtained group velocity maps reveal complex structures with clear velocity contrasts between sedimentary basins and crystalline rocks. The Bohemian Massif and the Northern Calcareous Alps are associated with fast-velocity bodies. By contrast, the Vienna Basin presents clear low-velocity zones with group velocities down to 2 km/s at period of 7 s. The group velocities are then inverted to 3D images of shear wave speeds using the linear inversion method of Herrmann (2013). The results highlight the complex crustal structure and complement earthquake tomography studies in the region. Updated

  2. Towards a global-scale ambient noise cross-correlation data base

    Science.gov (United States)

    Ermert, Laura; Fichtner, Andreas; Sleeman, Reinoud

    2014-05-01

    We aim to obtain a global-scale data base of ambient seismic noise correlations. This database - to be made publicly available at ORFEUS - will enable us to study the distribution of microseismic and hum sources, and to perform multi-scale full waveform inversion for crustal and mantle structure. Ambient noise tomography has developed into a standard technique. According to theory, cross-correlations equal inter-station Green's functions only if the wave field is equipartitioned or the sources are isotropically distributed. In an attempt to circumvent these assumptions, we aim to investigate possibilities to directly model noise cross-correlations and invert for their sources using adjoint techniques. A data base containing correlations of 'gently' preprocessed noise, excluding preprocessing steps which are explicitly taken to reduce the influence of a non-isotropic source distribution like spectral whitening, is a key ingredient in this undertaking. Raw data are acquired from IRIS/FDSN and ORFEUS. We preprocess and correlate the time series using a tool based on the Python package Obspy which is run in parallel on a cluster of the Swiss National Supercomputing Centre. Correlation is done in two ways: Besides the classical cross-correlation function, the phase cross-correlation is calculated, which is an amplitude-independent measure of waveform similarity and therefore insensitive to high-energy events. Besides linear stacks of these correlations, instantaneous phase stacks are calculated which can be applied as optional weight, enhancing coherent portions of the traces and facilitating the emergence of a meaningful signal. The _STS1 virtual network by IRIS contains about 250 globally distributed stations, several of which have been operating for more than 20 years. It is the first data collection we will use for correlations in the hum frequency range, as the STS-1 instrument response is flat in the largest part of the period range where hum is observed, up to a

  3. Monitoring seismic velocity changes caused by the 2014 Northern Aegean earthquake using continuous ambient noise records

    Science.gov (United States)

    Evangelidis, Christos; Daskalakis, Emmanouil; Tsogka, Chrysoula

    2016-04-01

    The 24 May 2014 Northern Aegean earthquake (6.9 Mw), an event on the Northern Aegean Trough (NAT), ruptured on two different fault segments with a total ruptured length of ~100 km. For the second delayed segment, rupture propagated eastward from the hypocenter for ˜65 km with a supershear velocity (5.5 km/s). Low-aftershock seismicity on the supershear segment implies a simple and linear fault geometry there. An effort to monitor temporal seismic velocity changes across the ruptured area of the Northern Aegean earthquake is underway. In recent years, neighboring seismic broadband stations near active faults have been successfully used to detect such changes. The crosscorrelation functions (CCF) of ambient noise records between stations yields the corresponding traveltimes for those inter-station paths. Moreover, the auto-correlation functions (ACF) at each station produce the seismic responce for a coincident source and receiver position. Possible temporal changes of the measured traveltimes from CCFs and ACFs correspond to seismic velocity changes. Initially, we investigate the characteristics and sources of the ambient seismic noise as recorded at permanent seismic stations installed around NAT at the surrounding islands and in mainland Greece and Turkey. The microseismic noise levels show a clear seasonal variation at all stations. The noise levels across the double frequency band (DF; period range 4-8 s) reflect the local sea-weather conditions within a range of a few hundred kilometers. Three years of continuous seismic records framing the main shock have been analysed from ~15 stations within a radius of 100 km from the epicentre. We observe a clear decrease of seismic velocities most likely corresponding to the co-seismic shaking. The spatial variation of this velocity drop is imaged from all inter-station paths that correspond to CCF measurements and for station sites that correspond to ACF measurements. Thus, we explore a possible correlation between co

  4. MSNoise: a Python Package for Monitoring Seismic Velocity Changes using Ambient Seismic Noise

    Science.gov (United States)

    Lecocq, Thomas; Caudron, Corentin; Brenguier, Florent

    2014-05-01

    We present MSNoise, a complete software suite to compute relative seismic velocity changes under a seismic network, using ambient seismic noise. The whole is written in Python, from the monitoring of data archives, to the production of high quality figures. All steps have been optimized to only compute the necessary steps and to use 'job'-based processing. All steps can be changed by matching the in/outs. MSNoise exposes an API for communication with the data archive and the database. We present a validation of the software on a dataset acquired during the UnderVolc project on the Piton de la Fournaise Volcano, La Réunion Island, France, for which precursory relative changes of seismic velocity are visible for three eruptions betwee 2009 and 2011. MSNoise is available on http://www.msnoise.org

  5. Structure of the Los Angeles Basin from ambient noise and receiver functions

    Science.gov (United States)

    Ma, Yiran; Clayton, Robert W.

    2016-09-01

    A velocity (Vs) and structure model is derived for the Los Angeles Basin, California based on ambient-noise surface wave and receiver-function analysis, using data from a low-cost, short-duration, dense broad-band survey (LASSIE) deployed across the basin. The shear wave velocities show lateral variations at the Compton-Los Alamitos and the Whittier Faults. The basement beneath the Puente Hills-San Gabriel Valley shows an unusually high velocity (˜4.0 km s-1) and indicates the presence of schist. The structure of the model shows that the basin is a maximum of 8 km deep along the profile and that the Moho rises to a depth of 17 km under the basin. The basin has a stretch factor of 2.6 in the centre grading to 1.3 at the edges and is in approximate isostatic equilibrium.

  6. Investigating Near Surface S-Wave Velocity Properties Using Ambient Noise in Southwestern Taiwan

    Directory of Open Access Journals (Sweden)

    Chun-Hsiang Kuo

    2015-01-01

    Full Text Available Ambient noise is typically used to estimate seismic site effects and velocity profiles instead of earthquake recordings, especially in areas with limited seismic data. The dominant Horizontal to Vertical Spectral Ratio (HVSR frequency of ambient noise is correlated to Vs30, which is the average S-wave velocity in the top 30 m. Vs30 is a widely used parameter for defining seismic amplification in earthquake engineering. HVSR can detect the vertical discontinuity of velocities, that is, the interfaces between hard bedrock and soft sediments. In southwestern Taiwan most strong motion stations are located in the plains and show a dominant frequency lower than 3 Hz. Several stations near the coast have low dominant frequencies of less than 1 Hz. The dominant frequencies are higher than 4 Hz at piedmont stations. The stations in the mountains with dominant frequencies over 8 Hz are typically located on very hard sites. This study analyzed the HVSR characteristics under different seismic site conditions considering the Vs30 from previous study (Kuo et al. 2012. The result implies that HVSRs are a better tool than Vs30 to classify the sites where bedrock is deeper than 30 m. Furthermore, we found a linear correlation between Vs30 and dominant HVSR frequency which could be used as a proxy of Vs30. The Vs30 map in this area was derived using the Engineering Geological Database for Taiwan Strong Motion Instrumentation Program (EGDT. The comparable distribution pattern between the dominant frequency and Vs30 demonstrate that HVSR can recognize S-wave velocity properties at the shallow subsurface.

  7. Crustal Structure beneath the Rwenzori Region of the Albertine Rift using Ambient-Noise Tomography

    Science.gov (United States)

    Kaviani, A.; Paul, A.; Rumpker, G.

    2015-12-01

    In this study we investigate the crustal structure beneath the Rwenzori region by analyzing a 1-year ambient-noise data set recorded by a network of 33 broadband seismic stations that have operated between September 2009 and August 2011. The Rwenzori region, located between the Democratic Republic of Congo and Uganda, is part of the western (Albertine) branch of the East African Rift System (EARS). The region of study is situated between the Albert Rift and the Edward Rift segments and covers an area of approximately 120 km by 50 km. The main objective of the seismological experiment was to address the questions of the uplift of the Rwenzori Mountains in an extensional regime and the absence of a crustal root beneath the mountain range. Any model proposed to address these questions requires the knowledge of the structure of the Rwenzori horst and surrounding rift shoulders. Previous results from local travel-time tomography revealed the presence of low-velocity anomalies in the upper crust beneath the mountain range relative to higher velocities in the surrounding shoulders. However, since the stations used in the previous study only covered the northern part of the region, the resolution of the models proposed by the body-wave tomography was very low beneath the Rwenzori Mountains. Hence, the limits of the Rwenzori horst at depth relative to the rift shoulders are still poorly known. The main objective of our ambient-noise tomography (ANT) is to provide an explanation for the building of Rwenzori Mountains. Due to the small aperture of the seismological network, we are mainly interested in the shallow crustal structure including the boundaries between the central Rwenzori horst and the surrounding rift shoulders as well as the variations in the thickness of the sedimentary basins. We expect that the ANT images will be able to delineate the boundaries between the main tectonic features including the limits of the Rwenzori horst at depth.

  8. Subsurface Characterization Beneath the Coso Geothermal Field by Ambient Noise Tomography

    Science.gov (United States)

    Ritzwoller, M. H.; Yang, Y.; Levshin, A. L.; Barmin, M. P.; Jones, C. H.

    2009-12-01

    The Coso Geothermal Area has been the subject of numerous geophysical studies over the past 30 years. Various seismological techniques have been applied to evaluate the regional stress distribution, velocity and attenuation structure of the subsurface. None of these studies has imaged subsurface shear velocity using surface waves generated either by local micro-earthquakes or by regional or teleseismic earthquakes, nor have any used interferometric methods based on ambient noise. In this study, we apply an interferometic method based on ambient seismic noise aimed at imaging the shallow shear velocity structure beneath the Coso Geothermal Area. Data are from a PASSCAL experiment deployed between 1998 and 2000 and regional broad-band seismometers operated by CalTech. Cross-correlations are performed between each pair of the COSO PASSCAL and CalTech stations for 15 months from March 1999 to May 2000. After compensating for or correcting instrumental irregularities and selecting reliable Rayleigh wave dispersion measurements from the inter-station cross-correlations, we obtain about 300 measurement paths as the basis for surface wave tomography at periods from 3 to 10 sec. Uncertainties of both group and phase velocity measurements are estimated using the variations among the dispersion curves from one-month cross-correlations in different months. The resulting dispersion maps reveal low group and phase velocities in the COSO volcanic field, especially at 3 sec period for group velocities, and high velocities to the east of the COSO volcanic field. The velocity variations are consistent with surface geological features, which encourages future inversion for 3-D shear velocity structure in the top 15 km of the crust.

  9. 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.

  10. 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.

  11. The uppermost crust structure of Ischia (southern Italy) from ambient noise Rayleigh waves

    Science.gov (United States)

    Strollo, R.; Nunziata, C.; Iannotta, A.; Iannotta, D.

    2015-05-01

    Ambient noise measurements were performed at the island of Ischia (southern Italy) along alignments of 2.4-7 km by using two three-component seismic stations. Synchronous noise recordings of 2-20 h were cross-correlated over 20-30 s windows, stacked and iteratively band-pass filtered to enhance the dispersive wave trains. Frequency time analysis was performed on the vertical and radial components of cross-correlations and the fundamental-mode Rayleigh wave group velocity was obtained. Validation of the dispersion data was possible with those obtained from an earthquake recording along a close path. The non-linear inversion of average Rayleigh wave group velocity dispersion curves along 13 paths (receiver inter-distances) allowed the definition of shear wave velocity models in the uppermost 1-2 km of the crust. The correlation of VS profiles vs. depth and drilling stratigraphy allowed to attribute VS lower than 1 km/s to tuffs and VS of 1.41 km/s to very fractured lavas. Higher VS are found in the central area of the island, in correspondence of the resurgent area. The top of the trachytic lava basement, with VS of 2.2-2.4 km/s and density of 2.3 g/cm3 is about 0.6-0.7 km deep b.s.l. in the centre of Ischia, below altered, very fractured lava or thermally altered tuff.

  12. Upper crustal structure of central Java, Indonesia, from transdimensional seismic ambient noise tomography

    Science.gov (United States)

    Zulfakriza, Z.; Saygin, E.; Cummins, P. R.; Widiyantoro, S.; Nugraha, A. D.; Lühr, B.-G.; Bodin, T.

    2014-04-01

    Delineating the crustal structure of central Java is crucial for understanding its complex tectonic setting. However, seismic imaging of the strong heterogeneity typical of such a tectonically active region can be challenging, particularly in the upper crust where velocity contrasts are strongest and steep body wave ray paths provide poor resolution. To overcome these difficulties, we apply the technique of ambient noise tomography (ANT) to data collected during the Merapi Amphibious Experiment (MERAMEX), which covered central Java with a temporary deployment of over 120 seismometers during 2004 May-October. More than 5000 Rayleigh wave Green's functions were extracted by cross-correlating the noise simultaneously recorded at available station pairs. We applied a fully non-linear 2-D Bayesian probabilistic inversion technique to the retrieved traveltimes. Features in the derived tomographic images correlate well with previous studies, and some shallow structures that were not evident in previous studies are clearly imaged with ANT. The Kendeng Basin and several active volcanoes appear with very low group velocities, and anomalies with relatively high velocities can be interpreted in terms of crustal sutures and/or surface geological features.

  13. 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

  14. Direct ambient noise tomography for 3-D near surface shear velocity structure: methodology and applications

    Science.gov (United States)

    Yao, H.; Fang, H.; Li, C.; Liu, Y.; Zhang, H.; van der Hilst, R. D.; Huang, Y. C.

    2014-12-01

    Ambient noise tomography has provided essential constraints on crustal and uppermost mantle shear velocity structure in global seismology. Recent studies demonstrate that high frequency (e.g., ~ 1 Hz) surface waves between receivers at short distances can be successfully retrieved from ambient noise cross-correlation and then be used for imaging near surface or shallow crustal shear velocity structures. This approach provides important information for strong ground motion prediction in seismically active area and overburden structure characterization in oil and gas fields. Here we propose a new tomographic method to invert all surface wave dispersion data for 3-D variations of shear wavespeed without the intermediate step of phase or group velocity maps.The method uses frequency-dependent propagation paths and a wavelet-based sparsity-constrained tomographic inversion. A fast marching method is used to compute, at each period, surface wave traveltimes and ray paths between sources and receivers. This avoids the assumption of great-circle propagation that is used in most surface wave tomographic studies, but which is not appropriate in complex media. The wavelet coefficients of the velocity model are estimated with an iteratively reweighted least squares (IRLS) algorithm, and upon iterations the surface wave ray paths and the data sensitivity matrix are updated from the newly obtained velocity model. We apply this new method to determine the 3-D near surface wavespeed variations in the Taipei basin of Taiwan, Hefei urban area and a shale and gas production field in China using the high-frequency interstation Rayleigh wave dispersion data extracted from ambient noisecross-correlation. The results reveal strong effects of off-great-circle propagation of high-frequency surface waves in these regions with above 30% shear wavespeed variations. The proposed approach is more efficient and robust than the traditional two-step surface wave tomography for imaging complex

  15. Crustal Structure of the Northern Chilean Forearc from Ambient Noise Tomography

    Science.gov (United States)

    Comte, D.; Carrizo, D.; Roecker, S. W.; Peyrat, S.; Arriaza, R.; Chi, R. K.; Baeza, S.

    2015-12-01

    In addition to being an excellent venue for investigating the tectonics of the Andean margin, northern Chile is of particular interest to seismologists because of its potential for an imminent megathrust earthquake. Such events often trigger destructive seismic activity in the populated forearc, as demonstrated for example in the aftermath of the 2010 Maule event. To investigate the nature of deformation in the forearc, we generated high resolution images of the subsurface from Rayleigh wave dispersion curves derived from cross correlation of ambient noise. The ambient noise data were recorded over a period of three years by 60 stations from three different networks of broad band stations. Because of the proximity of the stations to the Pacific Ocean, we estimated the bias in the estimated Green's functions caused by the asymmetry of the noise distribution using a technique based on that described by Yao and van der Hilst (2009). Our results suggest that this bias can be as large as 5% for some station pairs. The unbiased times are then used to refine phase velocity maps, from which we derived transit times to generate a 3D image of shear wavespeed (Vs) from the surface to about 50 km depth. To first order, low-Vs anomalies correlate well with the geometry of the Atacama Bench Structure (western foreland basin) where leaching processes are related to large incisions in the Atacama Desert (north of 19ºS). In addition, high Vs anomalies correlate with the locations of fossil magmatic arcs developed as trench-parallel belts from the coast to the Altiplano. For example, high Vs correlates with the Jurassic-Cretaceous magmatic arc along the coast, the Paleocene-Oligocene magmatic arc in the central depression, and the Eocene-Oligocene magmatic arc in the Frontal Cordillera. A continuous seismic anomaly of low-Vs, located between 15 - 25 km depth, may be evidence of a weak and/or hydrated zone within the lower continental crust, related to slab-linked upper plate

  16. Feasibility of retrieving time-lapse reflection signals using ambient-noise seismic interferometry at Ketzin, Germany

    NARCIS (Netherlands)

    Boullenger, B.; Verdel, A.; Paap, B.; Draganov, D.S.

    2015-01-01

    Ambient-noise seismic interferometry (ANSI) applied to passive body-wave measurements retrieves an estimate of the reflection response as if from a source at a receiver position. Often, the limited compliance with theoretical assumptions causes erroneous absolute amplitudes of the retrieved physical

  17. Studying CO2 storage with ambient-noise seismic interferometry: A combined numerical feasibility study and field-data example for Ketzin, Germany

    NARCIS (Netherlands)

    Boullenger, B.; Verdel, A.; Paap, B.; Thorbecke, J.W.; Draganov, D.S.

    2015-01-01

    Seismic interferometry applied to ambient-noise measurements allows the retrieval of the seismic response between pairs of receivers. We studied ambient-noise seismic interferometry (ANSI) to retrieve time-lapse reflection responses from a reservoir during CO2 geologic sequestration, using the case

  18. Seismic local site effects characterization in the Andarax River Valley (SE Spain) from ambient seismic noise

    Science.gov (United States)

    Carmona, Enrique; García-Jerez, Antonio; Luzón, Francisco; Sánchez-Martos, Francisco; Sánchez-Sesma, Francisco J.; Piña, José

    2014-05-01

    This work is focused on the characterization of seismic local effects in the Low Andarax River Valley (SE Spain). The Low Andarax River valley is located in an active seismic region, with the higher seismic hazard values in Spain. The landform is composed mainly by sedimentary materials which increase its seismic hazard due to the amplification of the seismic inputs and spectral resonances. We study seismic local effects in the Low Andarax River by analyzing the Horizontal-to-Vertical Spectral Ratio (HVSR) of ambient noise records. The noise data were recorded during two field campaigns in 2012 and 2013. There have been a total of 374 noise measurements with 15 and 30 minutes duration. The acquisition was performed with a Digital Broadband Seismometer Guralp CMG-6TD. The distance between measurements was about 200 meters, covering an area around 40 km2. There have been 6 significant peak frequencies between 0.3 Hz and 5 Hz. It was possible to find interesting areas with similar spectral peaks that coincide with zones with similar microgravimetric anomalies at the alluvial valley. It is also observed a decrease in the frequency peaks from West to East suggesting increased sediment layer. We also compute the soil models at those sites where geotechnical information is available, assuming that the seismic noise is diffuse. We invert the HVSR for these places using horizontally layered models and in the imaginary part the Green functions at the source. It is observed that the S wave velocity inverted models are consistent with the known geotechnical information obtained from drilled boreholes. We identify the elastodynamic properties of the limestone-dolomite materials with a formation of phyllites and quartzite that form the basement of the depression, and those properties of the Miocene and Pliocene detrital deposits (marls, sandy silts, sands and conglomerates) that fill the valley. These results together with the observed resonant frequencies along the Andarax

  19. Comparison between two methods for forward calculation of ambient noise H/V spectral ratios

    Science.gov (United States)

    Garcia-Jerez, A.; Luzón, F.; Sanchez-Sesma, F. J.; Santoyo, M. A.; Albarello, D.; Lunedei, E.; Campillo, M.; Iturrarán-Viveros, U.

    2011-12-01

    The analysis of horizontal-to-vertical spectral ratios of ambient noise (NHVSR) is a valuable tool for seismic prospecting, particularly if both a dense spatial sampling and a low-cost procedure are required. Unfortunately, the computation method still lacks of a unanimously accepted theoretical basis and different approaches are currently being used for inversion of the ground structure from the measured H/V curves. Two major approaches for forward calculation of NHVSRs in a layered medium are compared in this work. The first one was developed by Arai and Tokimatsu (2004) and recently improved by Albarello and Lunedei (2011). It consists of a description of the wavefield as generated by Far Surface point Forces (FSF method). The second one is based on the work of Sánchez-Sesma et al. (2011) who consider ambient noise as a Diffuse WaveField (DWF method), taking advantage of the proportionality between its Fourier-transformed autocorrelation (power spectrum) and the imaginary part of the Green function when source and receiver are the same. In both methods, the NHVSR is written as (PH/PV)1/2, where PH and PV are the horizontal and vertical power spectra. In the FSF method these quantities are given by PV∝⊙m(1+1/2χm2α2)(ARm/kRm)2 PH∝⊙m{(1+1/2χm2α2)(ARm/kRm)2χm2+1/2α2(ALm/kLm)2} where kRm, χm and ARm are wavenumber, ellipticity and medium response of the m-th Rayleigh wave mode; kLm and ALm correspond to the m-th Love wave mode and α is the horizontal-to-vertical load ratio of the ambient noise sources. Some common factors are omitted in the expressions of PV and PH. On the other hand, the DWF method deals with the full wavefield including both surface and body waves. In order to make the comparison easier, and taking into account that surface waves are often the dominant components in wide spectral ranges, body wave contributions are neglected here. In this case, the PH and PV power spectra for the DWF method are reduced to the simple expressions: PV

  20. 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

  1. Structure of the North Anatolian Fault Zone from the Autocorrelation of Ambient Seismic Noise

    Science.gov (United States)

    Taylor, George; Rost, Sebastian; Houseman, Gregory

    2016-04-01

    In recent years the technique of cross-correlating the ambient seismic noise wavefield at two seismometers to reconstruct empirical Green's Functions for the determination of Earth structure has been a powerful tool to study the Earth's interior without earthquakes or man-made sources. However, far less attention has been paid to using auto-correlations of seismic noise to reveal body wave reflections from interfaces in the subsurface. In principle, the Green's functions thus derived should be comparable to the Earth's impulse response to a co-located source and receiver. We use data from a dense seismic array (Dense Array for Northern Anatolia - DANA) deployed across the northern branch of the North Anatolian Fault Zone (NAFZ) in the region of the 1999 magnitude 7.6 Izmit earthquake in western Turkey. The NAFZ is a major strike-slip system that extends ~1200 km across northern Turkey and continues to pose a high level of seismic hazard, in particular to the mega-city of Istanbul. We construct body wave images for the entire crust and the shallow upper mantle over the ~35 km by 70 km footprint of the 70-station DANA array. Using autocorrelations of the vertical component of ground motion, P-wave reflections can be retrieved from the wavefield to constrain crustal structure. We show that clear P-wave reflections from the crust-mantle boundary (Moho) can be retrieved using the autocorrelation technique, indicating topography on the Moho on horizontal scales of less than 10 km. Offsets in crustal structure can be identified that seem to be correlated with the surface expression of the northern branch of the fault zone, indicating that the NAFZ reaches the upper mantle as a narrow structure. The southern branch has a less clear effect on crustal structure. We also see evidence of several discontinuities in the mid-crust in addition to an upper mantle reflector that we interpret to represent the Hales discontinuity.

  2. Ambient noise H/V spectral ratio in site effects estimation in Fateh jang area, Pakistan

    Institute of Scientific and Technical Information of China (English)

    S.M.Talha Qadri; Bushra Nawaz; S.H.Sajjad; Riaz Ahmad Sheikh

    2015-01-01

    Local geology or local site effect is a crucial component while conducting seismic risk assessment studies.Investigations made by utilization of ambient noise are an effective tool for local site estimation.The present study is conducted to perform site response analysis at 13 different sites within urban settlements of Fateh jang area (Pakistan).The aim of this study was achieved by utilizing Nakamura method or H/V spectral ratio method.Some important local site parameters,e.g.,the fundamental frequencies f0 of soft sediments,amplitudes A0 of corresponding H/V spectral ratios,and alluvium thicknesses over 13 sites within the study area,were measured and analyzed.The results show that the study area reflects low fundamental frequency f0.The fundamental frequencies of the sediments are highly variable and lie in a range of 0.6-13.0 Hz.Similarly,amplification factors at these sites are in the range of 2.0-4.0.

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

    International Nuclear Information System (INIS)

    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

  4. 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.

  5. Tomographic Imaging of Jakarta Area from Cross-correlation of Seismic Ambient Noise

    Science.gov (United States)

    Pranata, B.; Saygin, E.; Cummins, P. R.; Widiyantoro, S.; Nugraha, A. D.; Harjadi, P.; Suhardjono, S.

    2012-12-01

    Seismic imaging of sediment thickness of Jakarta is crucial where Jakarta city is currently being rapidly developed with major installations and high-rise structures being constructed at a fast pace. Therefore, information of surface geology and surface sediment thickness for Jakarta city is urgently required in order to mitigate the effects of earthquake hazards in the future. Because of this need, we deployed 36 broadband and shortperiod stations across Jakarta to record seismic ambient noise. We apply cross-correlation method to the simultaneously recorded data to retrieve interstation Green's functions. We measure group velocity dispersion of the retrieved Green's functions by applying narrowband filters. Dispersion measurements are then inverted with a nonlinear tomographic technique to image the shallow structure of Jakarta and its surrounding regions. Preliminary results from tomographic maps show low velocities dominantly located in central, west and north Jakarta. While the highest rate obtained is between stations in South Jakarta. This conforms with the known geological conditions in which the structure of sedimentary cover in northern Jakarta is thicker than the southern part.

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

    International Nuclear Information System (INIS)

    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)

  7. ambiental

    Directory of Open Access Journals (Sweden)

    Roque Leal Salcedo

    2008-01-01

    Full Text Available El derecho internacional ambiental es un conocimiento de carácter transversal, que entre otras consideraciones refleja las preocupaciones de la sociedad por la implementación de un modelo de desarrollo sustentable para el respeto a las reglas del medio natural que garantizan la integridad y renovación de los sistemas naturales. El presente artículo enfoca esta visión a través del análisis de material documental revisado, entre ellos tratados internacionales que permiten distinguir el desarrollo del derecho internacional ambiental y el papel de Organización de las Naciones Unidas (ONU, en el propósito común del derecho individual y colectivo de disfrutar de una vida, un ambiente seguro, sano y ecológicamente equilibrado. En función a estas disertaciones las consideraciones finales exponen parte de la visión que ha estructurado la ONU y que representan un aporte considerable en el fomento de la conciencia mundial sobre la necesidad de establecer vínculos entre las naciones para el continuo desarrollo de esta rama del derecho.

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

    OpenAIRE

    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 part of the Hellenic Unified Seismic Network. Inter-station istances between these stations ranged from 60 to 840 km and the number of station pairs was 2054. All signals were corrected for instru...

  9. Illumination of Geology and Recent Tectonic History in Idaho and Oregon from Persistent Scattering Extracted from Ambient Noise

    Science.gov (United States)

    Panning, M. P.; Russo, R. M.; Bremner, P. M.; Hongsresawat, S.; Mocanu, V. I.; Stanciu, A. C.; Torpey, M. E.; VanDecar, J. C.

    2014-12-01

    In the last decade, ambient noise techniques have revolutionized the ability to image crustal structure by allowing calculation of empirical Green's functions between stations through cross-correlation of noise records. Even with very long records, however, the resulting Green's functions still have noise in the sense of energy that cannot be simply modeled as the impulse response of a virtual source at the location of one station recorded at the other. Thanks to the extremely high quality and densely-spaced deployment of broadband sensors by the IDaho-ORegion (IDOR) flexible array deployment from 2011-2013 in western Idaho and eastern Oregon, we have identified signals in ambient noise cross-correlograms consistent with cross-correlated energy from persistent seismic scatterers near or within the seismic array. By using cross-correlograms from all available pairs of the 86 broadband sensors of the IDOR array and the permanent stations within the footprint of the array, BMO and HLID, we employ a Kirchoff-like stacking technique to image likely locations for such persistent scattering, which we call scattering intensity. The resulting scattering intensity maps show the highest scattering intensity correlated with the distribution of feeder dikes for the Columbia River Basalts, while the lowest scattering intensity is correlated with relatively undeformed regions of the Idaho Batholith. Overall, patterns of scattering intensity are clearly related with the surface geology and tectonic history of the region. This technique represents a new tool for extracting yet more information from the apparent noise in the signals extracted from ambient noise.

  10. Joint inversion of teleseismic and ambient noise Rayleigh waves for phase velocity maps, an application to Iceland

    Science.gov (United States)

    Harmon, Nicholas; Rychert, Catherine A.

    2016-08-01

    We present a method for joint inversion of teleseismic and ambient noise Rayleigh wave data for phase velocity maps from 18 to 50 s period. We adapt the two-plane wave method for teleseismic data to include ambient noise phase data. We apply the method to data from Iceland's ICEMELT and HOTSPOT arrays. Checkerboard tests show that the joint inversion improves phase velocity model recovery over methods that use the data sets independently, particularly at 18 s period. The addition of ambient noise data also extends resolution to shallower depths and shorter periods in comparison to previous teleseismic results beneath Iceland. We show there are significant differences in the phase velocity maps from the joint approach in comparison to other approaches, for instance, using only teleseismic data, only ambient noise data, or the mean of the two. The difference in phase velocities in turn affects the resulting shear velocity models. The advantage of the joint inversion is that it produces a single phase velocity map that satisfies both data sets simultaneously. Our phase velocity maps show a transition from low velocities centered beneath the main volcanic centers in Iceland at 18-25 s period, primarily crustal depths, to a low-velocity region that traces the rift zones from the Reykjanes Ridge in the south to the Kolbeinsey Ridge in the north at 29-50 s period, greater depths. These results are consistent with previous studies, although with an extended and improved region of resolution, which extends further into the Atlantic and Arctic Ocean.

  11. 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.

  12. Extraction of Stoneley and acoustic Rayleigh waves from ambient noise on ocean bottom observations

    Science.gov (United States)

    Tonegawa, T.; Fukao, Y.; Takahashi, T.; Obana, K.; Kodaira, S.; Kaneda, Y.

    2013-12-01

    In the interferometry, the wavefield propagating between two positions can be retrieved by correlating ambient noise recorded on the two positions. This approach is useful for applying to various kinds of wavefield, such as ultrasonic, acoustic (ocean acoustic), and also seismology. Off the Kii Peninsula, Japan, more than 150 short-period (4.5 Hz) seismometers, in which hydrophone is also cosited, had been deployed for ~2 months on 2012 by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) as a part of 'Research concerning Interaction Between the Tokai, Tonankai and Nankai Earthquakes' funded by Ministry of Education, Culture, Sports, Science and Technology, Japan. In this study, correlating ambient noise recorded on the sensors and hydrophones, we attempt to investigate characteristics of wavefield relative to the ocean, sediment, and solid-fluid boundary. The observation period is from Sep. 2012 to Dec. 2012. Station spacing is around 5 km. For 5 lines off the Kii Peninsula, the 30-40 seismometers are distributed at each line. Sampling interval is 200 Hz for both seismometer and hydrophone. The vertical component is just used in this study for correlation analysis. The instruments are located at 100-4800 m in water depth. In the processing for the both records, we applied a bandpass filter of 1-3 Hz, replaced the amplitude to zero if it exceeds a value that was set in this study, and took one-bit normalization. We calculated cross-correlation function (CCF) by using continuous records with a time length of 600 s, stacked the CCFs over the whole observation period. As a result of the analysis for hydrophone, a strong peak can be seen in the CCF for pairs of stations where the separation distance is ~5 km. Although the peak emerges in the CCFs for the separation distance up to 10 km, it disappears in the case that two stations are greater than 15 km separated. As a next approach, along a line off the Kii Peninsula, we aligned CCFs for two stations with

  13. Anisotropic Rayleigh wave tomography of Northeast China using ambient seismic noise

    Science.gov (United States)

    Liu, Zhikun; Huang, Jinli; Yao, Huajian

    2016-07-01

    The ambient noise data recorded by 249 seismic stations in the permanent and temporary networks in Northeast China are used to invert for the isotropic phase velocity and azimuthal anisotropy of Rayleigh waves in the period band 5-50 s. The inversion results reflect the structure from the shallow crust to upper mantle up to approximately 120 km depth. Beneath the Songliao basin, both the fast direction in shallow crust and strike of a low-velocity anomaly in the middle crust are NNE-SSW, which is coincident with the main tectonic trend of the (Paleo) Pacific tectonic domain. This indicates that the rifting of the Songliao basin is influenced by the subduction of (Paleo) Pacific plate. The upper mantle of Songliao block (except the central area of Songliao basin) to the west of Mudanjiang fault, and the east of the North-South Gravity Lineament, is characterized by high-velocity and weak anisotropy up to approximately ​120 km depth. We infer that there is delamination of lithospheric mantle beneath the Songliao block. Obvious N-S, NE-SW, and E-W trending fast directions are found in the lithospheric mantles of the east, west, and south sides of Songliao block, respectively, which coincide with the strikes of the Paleozoic tectonic in these areas. This suggests that the frozen-in anisotropic fabric in the lithospheric mantle can be used to indicate the historical deformation of the lithosphere. In the northern margin of the North China Craton, the spatial variations of phase velocity and azimuthal anisotropy are more dramatic than those in Northeast China blocks, which indicates that the lithosphere of the North China Craton has experienced more complicated tectonic evolution than that of the Northeast China blocks.

  14. Crustal structure of the Newer Volcanics Province, SE Australia, from ambient noise tomography

    Science.gov (United States)

    Jiang, Chengxin; Yang, Yingjie; Rawlinson, Nicholas; Griffin, William L.

    2016-06-01

    Intraplate volcanism is a widespread phenomenon, and is generally regarded to be independent of plate tectonics. The Newer Volcanics Province (NVP) of SE Australia represents the most recent (and arguably still active) intraplate volcanism on the Australian continent, and has been postulated to originate from the combined effect of localized shear flow and edge-driven convection. In this study, we adopt ambient noise tomography and Monte-Carlo inversion methods to construct the first local-scale 3D crustal Vs model of the NVP region with a resolution of ~ 35 km. The model displays distinct crustal velocity features near the eastern and western margins of the NVP, which may point to the existence of a lithosphere-scale plumbing system for the migration of melt associated with the boundary between the Delamerian Orogen and the Lachlan Orogen, which underlies the NVP. In particular, exceptionally high velocities are observed in the middle crust of the Delamerian Orogen, and are best explained by buried magmatic arcs. This interpretation is consistent with a subduction-accretion origin for the Delamerian Orogen. Trans-lithospheric faults might have developed during the accretion processes, providing possible pathways for the migration of NVP magmas to the crust and surface. Our 3D model also images small localized velocity reductions in the lower crust at the region where the two distinct lithospheric units meet. The low velocity zone is spatially correlated with the top of a prominent lithosphere-scale low-resistivity zone (10-30 Ωm), which we interpret to represent intruded magmatic sills with small proportions of melt remaining.

  15. Continent-arc collision in the Banda Arc imaged by ambient noise tomography

    Science.gov (United States)

    Porritt, Robert W.; Miller, Meghan S.; O'Driscoll, Leland J.; Harris, Cooper W.; Roosmawati, Nova; Teofilo da Costa, Luis

    2016-09-01

    The tectonic configuration of the Banda region in southeast Asia captures the spatial transition from subduction of Indian Ocean lithosphere to subduction and collision of the Australian continental lithosphere beneath the Banda Arc. An ongoing broadband seismic deployment funded by NSF is aimed at better understanding the mantle and lithospheric structure in the region and the relationship of the arc-continent collision to orogenesis. Here, we present results from ambient noise tomography in the region utilizing this temporary deployment of 30 broadband instruments and 39 permanent stations in Indonesia, Timor Leste, and Australia. We measure dispersion curves for over 21,000 inter-station paths resulting in good recovery of the velocity structure of the crust and upper mantle beneath the Savu Sea, Timor Leste, and the Nusa Tenggara Timur (NTT) region of Indonesia. The resulting three dimensional model indicates up to ∼25% variation in shear velocity throughout the plate boundary region; first-order velocity anomalies are associated with the subducting oceanic lithosphere, subducted Australian continental lithosphere, obducted oceanic sediments forming the core of the island of Timor, and high velocity anomalies in the Savu Sea and Sumba. The structure in Sumba and the Savu Sea is consistent with an uplifting forearc sliver. Beneath the island of Timor, we confirm earlier inferences of pervasive crustal duplexing from surface mapping, and establish a link to underlying structural features in the lowermost crust and uppermost mantle that drive upper crustal shortening. Finally, our images of the volcanic arc under Flores, Wetar, and Alor show high velocity structures of the Banda Terrane, but also a clear low velocity anomaly at the transition between subduction of oceanic and continental lithosphere. Given that the footprint of the Banda Terrane has previously been poorly defined, this model provides important constraints on tectonic reconstructions that

  16. Dynamic characteristics of an active coastal spreading area using ambient noise measurements—Anchor Bay, Malta

    Science.gov (United States)

    Galea, Pauline; D'Amico, Sebastiano; Farrugia, Daniela

    2014-11-01

    Anchor Bay and surrounding regions are located on the northwest coast of the island of Malta, Central Mediterranean. The area is characterized by a coastal cliff environment having an outcropping layer of hard coralline limestone (UCL) resting on a thick (up to 50 m) layer of clays and marls (Blue Clay, BC). This configuration gives rise to coastal instability effects, in particular lateral spreading phenomena and rock falls. Previous and ongoing studies have identified both lateral spreading rates and vertical motions of several millimetres per year. The area is an interesting natural laboratory as coastal detachment processes in a number of different stages can be identified and are easily accessible. We investigate the site dynamic characteristics of this study area by recording ambient noise time-series at more than 30 points, over an area of 0.07 km2, using a portable three-component seismograph. The time-series are processed to give both horizontal-to-vertical spectral ratio graphs (H/V) as well as frequency-dependent polarisation analysis. The H/V graphs illustrate and quantify aspects of site resonance effects due both to underlying geology as well as to mechanical resonance of partly or wholly detached blocks. The polarization diagrams indicate the degree of linearity and predominant directions of vibrational effects. H/V curves closer to the cliff edge show complex responses at higher frequencies, characteristic of the dynamic behaviour of individual detached blocks. Particle motion associated with the higher frequencies shows strongly directional polarization and a high degree of linearity at well-defined frequencies, indicative of normal-mode vibration. The stable plateau areas, on the other hand, show simple, single-peak H/V curves representative of the underlying stratification and no predominant polarization direction. These results, which will be compared with those from other experiments in the area, have important implications for the

  17. Ice shelf structure derived from dispersion curve analysis of ambient seismic noise, Ross Ice Shelf, Antarctica

    Science.gov (United States)

    Diez, A.; Bromirski, P. D.; Gerstoft, P.; Stephen, R. A.; Anthony, R. E.; Aster, R. C.; Cai, C.; Nyblade, A.; Wiens, D. A.

    2016-05-01

    An L-configured, three-component short period seismic array was deployed on the Ross Ice Shelf, Antarctica during November 2014. Polarization analysis of ambient noise data from these stations shows linearly polarized waves for frequency bands between 0.2 and 2 Hz. A spectral peak at about 1.6 Hz is interpreted as the resonance frequency of the water column and is used to estimate the water layer thickness below the ice shelf. The frequency band from 4 to 18 Hz is dominated by Rayleigh and Love waves propagating from the north that, based on daily temporal variations, we conclude were generated by field camp activity. Frequency-slowness plots were calculated using beamforming. Resulting Love and Rayleigh wave dispersion curves were inverted for the shear wave velocity profile within the firn and ice to ˜150 m depth. The derived density profile allows estimation of the pore close-off depth and the firn-air content thickness. Separate inversions of Rayleigh and Love wave dispersion curves give different shear wave velocity profiles within the firn. We attribute this difference to an effective anisotropy due to fine layering. The layered structure of firn, ice, water and the seafloor results in a characteristic dispersion curve below 7 Hz. Forward modelling the observed Rayleigh wave dispersion curves using representative firn, ice, water and sediment structures indicates that Rayleigh waves are observed when wavelengths are long enough to span the distance from the ice shelf surface to the seafloor. The forward modelling shows that analysis of seismic data from an ice shelf provides the possibility of resolving ice shelf thickness, water column thickness and the physical properties of the ice shelf and underlying seafloor using passive-source seismic data.

  18. 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.

  19. Crustal structure of the Pannonian-Carpathian region, Central Europe, from ambient noise tomography

    Science.gov (United States)

    Ren, Y.; Stuart, G. W.; Houseman, G. A.; Carpathian Basins Project Working Group

    2010-12-01

    The Pannonian Basin of Central Europe is a major extensional basin surrounded by the Carpathian Mountains. During the evolution of the Carpathian-Pannonian region, extension of the crust and lithosphere created several inter-related basins of which the Pannonian basin is the largest. Imaging the seismic velocity structure of the crust and the upper mantle may help us understand the structure and geodynamic evolution of this part of central Europe. Here, we use ambient noise tomography to investigate the crust and uppermost mantle structure in the region. We have collected and processed continuous data from 56 temporary stations deployed in the Carpathian Basins Project (CBP) for 16 months (2005-2007) and 41 permanent broadband stations; this dataset enables the most well-resolved images of the S-wave structure of the region yet obtained. We computed the cross-correlation between vertical component seismograms from pairs of stations and stacked the correlated waveforms over 1-2 years to estimate the Rayleigh wave Green’s function. Frequency-time analysis is used to measure the group velocity dispersion curves, which are then inverted for the group velocity maps. Our 4-10 s group velocity maps exhibit low velocity anomalies which clearly defined the major sediment depo-centers in the Carpathian region. A broad low velocity anomaly in the center of the 5 s group velocity map can be associated with the Pannonian Basin, whereas an anomaly in the southeastern region is related to the Moesian platform. Further east, the Vienna Basin can also be seen on our maps. A fast anomaly in the central region can be associated with the Mid-Hungarian line. At periods from 18 to 24 seconds, group velocities become increasingly sensitive to crustal thickness. The maps also reveal low-velocity anomalies associated with the Carpathians. The low velocity anomalies are probably caused by deeper crustal roots beneath the mountain ranges which occur due to isostatic compensation. CBP

  20. Fine Crustal Structure in the Northwestern Iranian Plateau Revealed by Ambient Noise Tomography

    Science.gov (United States)

    Jiang, Mingming; Chen, Ling; Talebian, Morteza; Ghods, Abdolreza; Ai, Yinshuang; Sobouti, Farhad; He, Yumei; Motaghi, Khalil; Chen, Qi-Fu; Lyv, Yan; Xiao, Wenjiao

    2016-04-01

    Detailed information about the crustal and lithospheric structures is crucial for understanding the geodynamics processes of continental collision and subsequent mountain building. Being at the initial stage of continental collision, the Iranian Plateau has not been well studied due to the lack of high-resolution, robust images of the crustal and lithospheric structures. Along the Zagros Orogen in the NW part of the Iranian Plateau the Arabian Plate has collided with the Eurasian Plate since about 30 Ma ago, whereas in the Makran region to the southeast oceanic subduction underneath the Eurasian Plate is still an ongoing process. For better understanding the geodynamic processes from subduction to collision, we planned to deploy multiple dense seismic arrays sampling regions at different tectonic stages in the Iranian Plateau. Up to now, we have finished the first seismic array observation in NW Iran. Based on the high quality data recorded, we conduct ambient noise tomography to investigate the fine crustal structure of the area from the south of the Zagros to the coast of the Southern Caspian Sea. Our results revel a salient decoupling between the upper crust and lower crust in the Zagros. The upper crust is slow, likely due to the effects of thick sediments, and displays a consistent anisotropy pattern with a NW-SE fast shear-wave direction, which is proximately parallel to the strike of the Zagros Orogen. The middle to lower crust, on the other hand, shows low-to-high velocity variations with depth and anisotropic fabrics trending to NE-SW, which is perpendicular to the strike of the orogen. Combined with the imaging results from receiver functions, we suggest that the collision between the Arabian and Eurasian Plates has caused strong crustal deformation and localized thickening of the lower crust beneath the Zagros. We also find a high velocity anomaly in the lower crust beneath the Alborz Mountain, isolated from the low velocities beneath the central Iran

  1. Highly variable structure along the Banda arc imaged by ambient noise tomography

    Science.gov (United States)

    Porritt, R. W.; Miller, M. S.; O'Driscoll, L.; Harris, C. W.; Roosmawati, N.

    2015-12-01

    The tectonic configuration of the Banda region in southeast Asia captures the spatial transition from subduction of Indian Ocean lithosphere to subduction and collision of the Australian continental lithosphere beneath the Timor Sea, which can be considered as the temporal transition of the initiation of continental collision. An ongoing broadband seismic deployment funded by NSF is aimed at better understanding the mantle and lithospheric structure in the region and the relationship of the arc-continent collision to orogenesis. Here, we present results from ambient noise tomography in the region utilizing this temporary deployment of 30 broadband instruments and 38 permanent stations in Indonesia and Australia. Despite having only a year of data from the new experiment and about 2.5 years of data in total, we are already able to measure stable dispersion curves for several paths resulting in good recovery for the Savu Sea, Timor Leste, and the Nusa Tenggara Timur (NTT) region of Indonesia. The resulting initial three dimensional shear velocity model indicates significant lateral heterogeneity along the plate boundary. The model contains clear anomalies associated with the subducting oceanic lithosphere, subducted Australian continental lithosphere, and perhaps delaminated oceanic sediments forming the core of the island of Timor. In this initial 3D model, the subducted lithosphere appears to shallow under the islands of Timor and Sumba relative its position beneath to the Savu Sea where oceanic or transitional lithosphere is being subducted. Additionally, a low velocity anomaly associated with the island of Timor from near the surface to ~8 km depth is observed. Under the island of Sumba, a high velocity anomaly is observed between 10 and 20 km depths. These differences may reflect variation in the stage of subduction along strike, compositional variations, or the influences of subducting seamounts such as the Scott Plateau. Finally, we observe localized low

  2. 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

  3. 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...... pollution affected risk for fatal strokes. There were indications of combined effects....... 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...

  4. Time-lapse CO2 monitoring using ambient-noise seismic interferometry: a feasibility study from Ketzin, Germany

    Science.gov (United States)

    Boullenger, Boris; Verdel, Arie; Paap, Bob; Thorbecke, Jan; Draganov, Deyan

    2015-04-01

    Seismic interferometry applied to ambient-noise measurements allows retrieval of the Green's function between two seismic receivers, by cross-correlating their recordings, as if from a source at one of the receivers. We propose to use ambient-noise seismic interferometry (ANSI) to retrieve reflection data. The time-lapse differences between different vintages of the retrieved data may help characterize property changes within a geologic reservoir with varying CO2 saturation. We test the feasibility of this time-lapse passive seismic method with numerical experiments based on the CO2-storage site of Ketzin, Germany. Ambient-noise recordings from Ketzin exhibit significant passive body-wave energy (from natural tremors or induced seismicity in the vicinity of the reservoir), which is advantageous to retrieve reflections with ANSI. The ANSI numerical experiments aim to understand what the requirements are for the recorded body-wave noise to retrieve the time-lapse reflection signal caused by an increase of CO2 saturation in the reservoir. For this purpose, we design two velocity scenarios at Ketzin: a base scenario before the injection of CO2, and a repeat scenario corresponding to a P-wave velocity decline in the reservoir by 20 percent. For both scenarios, we simulate passive seismic experiments of body-wave noise recordings that may take several days or months to record in the field. The passive recordings are obtained by modelling global (direct wave, internal and surface multiples) transmission responses from band-limited subsurface noise sources, randomly triggered in space and time. The time-lapse reflection signal is obtained by taking the differences between the base and the repeat retrieved reflection data (virtual common-shot gathers). We found that the time-lapse signal is still recovered with ANSI even if the base and repeat retrieved reflection data are partially polluted with artifacts. This means that uneven illumination of the array does not

  5. Extracting the Group Velocity of Rayleigh Waves from the Cross Correlation of the Ambient Seismic Noise Between Two Seismic Stations

    Institute of Scientific and Technical Information of China (English)

    Jin Xing; Li Jun; Lin Shu; Zhou Zhengrong; Kang Lanchi; Ou Yiping

    2008-01-01

    This paper uses the 8 broad-band stations' microseism data recorded by the Seismic Monitoring Network of Fujian Province to calculate the vertical correlation coefficient between two stationsat intervals of 5 minutes. According to the time intervals technique we obtain the different coefficients and then add the correlative coefficients. Depending on this, we extract the group velocity of Rayleigh waves from the cross correlation of the ambient seismic noise between two seismic stations and figure out the group velocity' spatial distribution. The results show that the signal noise ratio (SNR) increases proportionally to the superposition times, but the results from different days are similar to one another. Synchronously, the arrival-time is also stable and there is no obvious change when coming across typhoons. It is found the velocity of the surface wave is 2.9~3. 1km/s in Fujian Province, which is close to the observationally attained value.

  6. 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.

  7. High Spatial Density Ambient Noise Tomography at the El Jefe Geyser, Chile

    Science.gov (United States)

    Hakso, A. W.; Seats, K.

    2015-12-01

    The El Jefe geyser in the Atacama Desert, Chile has been the subject of study to better understand processes of heat transport and eruption mechanisms in geyser systems (Munoz-Saez et al., 2015). Existing seismological literature on geyser and volcanic systems is predominantly focused on seismicity generated in the eruptive process (Benoit and McNutt, 1997; O'Brien et al., 2011). In contrast, this study leverages seismic noise in the repose period to generate an approximation to the Green's function for each receiver pair, known as noise correlation functions (NCFs). A dense seismic array of 51 geophones spaced at 2-10 meter intervals recorded several days of data at a spatial scale and frequency range approximately two orders of magnitude removed from prior seismic interferometry studies. While eruptions of the El Jefe geyser impose a transient signal on a diffuse background noise, a regular eruption interval of 132.52.5 seconds (Munoz-Saez et al., 2015) allows for reliable removal of seismic energy associated with the eruption, improving the azimuthal distribution of noise across the array. The approach to generating noise correlation functions closely follows the methodology of Seats and Lawrence (2014). Moveout of at least two phases of energy is apparent in the calculated NCFs, suggesting that multiple phases of seismic energy may be present in the noise, moving coherently across the array.

  8. 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.

  9. 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 tho

  10. Imaging fluid channels within the NW Bohemia/Vogtland region using ambient seismic noise and MFP analysis

    Science.gov (United States)

    Umlauft, Josefine; Flores Estrella, Hortencia; Korn, Michael

    2016-04-01

    Presently ongoing geodynamic processes within the intracontinental lithospheric mantle give rise to different natural phenomena in the NW Bohemia/Vogtland region, among others: earthquake swarms, mineral springs and degassing zones of mantle-derived fluids (mofettes). Their interaction mechanisms and relations are not yet fully understood, therefore they are intensively studied using geophysical, geological and biological approaches. We focus on the investigation of near-surface channels that conduct mantle-originating fluids as well as CO2 near the Earth's surface. We aim at the detection, imaging and characterization of the fluid channel structure as well as the observation of their temporal and spatial variability. The Hartoušov Mofette Field within the Cheb Basin (NW Bohemia/Vogtland region) is a key site to study fluid flow as it is characterized by strong surface degassing of CO2. On this field, we applied the noise source localization method Matched Field Processing (MFP) considering the fluid flow as seismic noise source. Within multiple campaigns, we measured ambient seismic noise in continous mode during the night to avoid cultural noise generated by human activity. We used arrays of about 30 randomly distributed stations with 1 to 4 ha extent. We compared the surface position of the MFP output with punctual CO2 flux measurements performed by Nickschick et al. (2015) and observed a strong relation between high CO2 flux values and the position of the MFP maxima. Additionally, we observed surface indicators for CO2 degassing on the same positions of the MFP predicted noise sources: wet and dry mofettes accompanied by bog cotton, bug traps and brown to yellow coloured grass. The MFP maxima can be followed into the subsoil to image the fluid channel structure down to 50 m depth. We analyzed the influence of the array size on the vertical and horizontal MFP resolution as well as the temporal and spatial variability of the flow activity.

  11. Resolution for a local earthquake arrival time and ambient seismic noise tomography around the Eyjafjallajökull volcano

    Science.gov (United States)

    Benediktsdóttir, Á.; Gudmundsson, Ö.; Tryggvason, A.; Bödvarsson, R.; Brandsdóttir, B.; Vogfjörd; K.; Sigmundsson, F.

    2012-04-01

    The explosive summit eruption of Eyjafjallajökull volcano from 14 April to end of May 2010 was preceded by an effusive flank eruption of the volcano (at Fimmvörðuháls) March 20th - April 12th. These eruptions culminated 18 years of recurrent volcanic unrest in the area, with extensive seismicity and high deformation rates since beginning of January 2010. A national network of seismic stations in Iceland (the SIL network), operated by he Icelandic Meteorological Office, monitored the precursors and development of the eruptions, in real time. We analyse a seismic dataset available from SIL stations in the vicinity of the eruption area, as well as data from additional portable stations that were deployed during a period of unrest in 1999 and just before and during the eruptions in 2010. The SIL system detected and located 2328 events between early March and late May 2010 in the area around Eyjafjallajökull. Here we present a preliminary evaluation of resolution for a local earthquake arrival time tomography. Adding the portable stations to the pre-existing SIL data set is crucial in order to identify more seismic events and improve the data coverage for tomography. We also present a resolution analysis for Ambient Seismic Noise Tomography (ASNT) in the area. In this method ambient seismic noise, recorded at two seismic stations, is cross-correlated. This band-limited approximation of the Green's function between two stations is used to estimate surface wave velocities. The fundamental assumptions underlying this method is that the noise is constructed from a randomly distributed wavefield, but this may be violated by volcanic tremor during the eruptions. We evaluate the robustness of inter-station correlograms as a function of time during the unrest period as well as their frequency content for evaluation of depth resolution. The results can be compared to constraints on magma movements inside the volcano based on interpretation of crustal deformation and

  12. 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 usu

  13. Crustal properties in the continuum Baltic Shield-Scandinavian Mountains from seismic ambient noise and magnetotelluric analysis

    Science.gov (United States)

    Ben Mansour, Walid; England, Richard W.; Fishwick, Stewart; Köhler, Andreas; Moorkamp, Max; Ottemøller, Lars; Smirnov, Maxim

    2016-04-01

    The Scandinavian passive margin is a good example of a region where a Precambrian shield is directly in contact with a younger mountain belt. Located along the Atlantic coast, the Scandinavian mountains, formed 440 Ma ago, show high peaks (> 1 km from the sea level) due to an uplift event 12 Ma ago. This topography contrasts strongly with the low topography of the Baltic shield (around 500 m from the sea level). If the mountain shows high topography compared to the shield, P-receiver functions analysis indicates that the Moho is deeper beneath the shield than beneath the orogenic belt. This result is surprising, as simple crustal isostasy would produce the opposite result. It is therefore likely that there is further variation in crustal and lithospheric properties between the shield and the mountain belt. In this perspective, several geophysical experiments (SCANLIPS2, POLENET-LAPNET, SCANLIPS3D, Norwegian National Seismic Network) have been deployed in the region in order to better understand the lateral variation in the crustal properties. From these different seismic arrays, we used the technique of ambient noise cross correlation in order to reconstruct the Rayleigh wave Green's function (R-R and Z-Z components) and produced a new Vs model of the upper crust in the transition between the Scandinavian mountains and Baltic Shield. In addition of this study, a magnetotelluric survey was done in the framework of MaSCa (MAgnetotellurics in the SCandes) project between 2011 and 2013 in the same area of broadband seismic network (Northern Scandinavia Mountains and the Baltic Shield). This project shows higher resistivity in the crust beneath the Baltic shield than beneath the orogenic belt. The results of this study are used in a joint inversion with seismic ambient noise in order to improve existing models. We used the multi objective genetic algorithms (GA) to inverse in the same time seismological data (receiver functions and dispersion curves from seismic ambient

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

    Science.gov (United States)

    Gokirmak, Ali; Inaltekin, Hazer; Tiwari, Sandip

    2009-08-19

    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 DeltaC(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. PMID:19636094

  15. 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

  16. Contribution of seasonal presence of cetaceans, earthquakes, drifting icebergs and anthropogenic activity to the ambient noise level in the Southern Indian Ocean

    Science.gov (United States)

    Tsang-Hin-Sun, Eve; Royer, Jean-Yves

    2015-04-01

    Assessing the ambient sound level in the oceans is essential for a better understanding of the interactions between the ecosystem and anthropogenic activities. Ambient noise studies conducted in the North Pacific and Atlantic oceans, have shown that since the 60's oceanic noise level increases with the ship traffic, even if potential impacts of shipping noise on the ecosystem is not yet fully understood. However long-term acoustic records for the Indian Ocean are still limited. Here we present long-term statistics on the ambient sound in the Southern Indian Ocean basin based on 2 years of data collected at 5 widely distributed autonomous hydrophones. The data consist of single hydrophone spectra (10-100 Hz in 1-Hz bins) averaged using Welch's method over 200 s. Spectral probability distributions of the ambient sound level are analyzed in order to identify the main sound sources and their geographical and time variability. The mean sound level within the array is 10 to 20 dB lower than in other oceans, revealing a weaker influence of shipping on the Southern Indian Ocean noise budget. Seismic events are evenly distributed in time and space and mostly contribute to the general low-frequency background noise. Periodic signals are mainly associated with the seasonal presence of 3 types of blue whales and fin whales whose signatures are easily identified at target frequencies. Winter lows and summer highs of the ambient noise levels are also well correlated with ice volume variations. Icebergs are found to be a major sound source, strongly contributing to seasonal variations even at northernmost sites of the array. Although anthropogenic factors do not seem to dominate the noise spectrum, shipping sounds are present north and east of the array. Observed higher sound levels are consistent with the proximity of major traffic lanes.

  17. Data analysis results of the second sea trial of ambient noise imaging with acoustic lens in 2014: Two-dimensional target images affected by direction of field of view and spatial noise distribution

    Science.gov (United States)

    Mori, Kazuyoshi; Ogasawara, Hanako; Tsuchiya, Takenobu; Endoh, Nobuyuki

    2016-07-01

    An aspherical lens with an aperture diameter of 1.0 m has been designed and fabricated to develop a prototype system for ambient noise imaging (ANI). A sea trial of silent target detection using the prototype ANI system was conducted under only natural ocean ambient noise at Uchiura Bay in November 2010. It was verified that targets are successfully detected under natural ocean ambient noise, mainly generated by snapping shrimps. Recently, we have built a second prototype ANI system using an acoustic lens with a two-dimensional (2D) receiver array with 127 elements corresponding to a field of view (FOV) spanning 15° horizontally by 9° vertically. In this study, we investigated the effects of the direction of the FOV and the spatial noise distribution on the 2D target image obtained by ANI. Here, the noise sources in front of the target are called “front light”, and those at the rear of the target are called “back light”. The second sea trial was conducted to image targets arranged in the FOV and measure the positions of noise sources at Uchiura Bay in November 10–14, 2014. For front light, the pixel values in the on-target directions were greater than those in other directions owing to the dominant target scatterings. Reversely, for back light, the pixel values in the on-target directions were lower than those in other directions owing to the dominant direct noises such as “silhouette”.

  18. 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.

  19. Preliminary Results of Crustal Structure beneath the Wabash Valley Seismic Zone Using Teleseismic Receiver Functions and Ambient Noise Tomography

    Science.gov (United States)

    Zhu, L.; Aziz Zanjani, A.; Hu, S.; Liu, Y.; Herrmann, R. B.; Conder, J. A.

    2015-12-01

    As part of a on-going EarthScope FlexArray project, we deployed 45 broadband seismographs in a 300-km-long linear profile across the Wabash Valley Seismic Zone (WVSZ). Here we present preliminary results of crustal structure beneath WVSZ based on teleseismic receiver functions and ambient noise tomography. We combined waveform data of the temporary stations in 2014 with those of permanent seismic stations and the transportable array stations in our study area since 2011. We found 656 teleseismic events with clear P-wave signals and obtained 2657 good-quality receiver functions of 84 stations using a time-domain iterative deconvolution method. We estimated crustal thickness and Vp/Vs ratio beneath each station using the H-κ stacking method. A high-resolution crustal structural image along the linear profile was obtained using the Common-Conversion-Point (CCP) stacking method. We also measured Rayleigh-wave phase and group velocities from 5 to 50 s by cross-correlating ambient noises between stations and did joint-inversion of receiver functions and surface wave dispersions for S-velocity structures beneath selected stations. The results show that the average crustal thickness in the region is 47 km with a gentle increase of crustal thickness from southeast to northwest. A mid-crustal interface is identified in the CCP image that also deepens from 15 km in the southeastern end to >20 km in the northwest. The CCP image shows that the low-velocity sedimentary layer along the profile is broad and is thickest (~10 km) near the center of the Wabash Valley. Beneath the center of the Valley there is a 40-km-wide positive velocity discontinuity at a depth of 40 km in the lower crust that might be the top of a rift pillow in this failed continental rift. Further results using 3D joint inversion and CCP migration will be presented at the meeting.

  20. Natural Migration of Scattered Surface Waves from Correlated Ambient Noise: Applications on Long Beach Array and US-Array

    Science.gov (United States)

    AlTheyab, A.; Workman, E. J.; Lin, F. C.; Schuster, G. T.

    2014-12-01

    Correlation of ambient seismic noise gives traces that are an approximation to the time-derivative of the Green's function between two recording stations. These empirical Greens functions often contain the incident surface-waves and backscattered waves, which can be migrated to image near-surface discontinuities and scatterers. Traditional migration approaches require an approximation of the near-surface velocity field and proper modeling of elastic waves to estimate the Green's functions from the source and receiver positions to every image-point. With dense passive seismic array acquisition and ambient noise cross-correlations, each station can be considered as both a virtual source and a receiver and near-surface scatterers can be imaged across the array using only the empirical Green's functions. This new imaging approach is referred to as natural migration because the Green's functions needed for migration are naturally estimated from the crosscorrelograms of recorded traces. The advantages of natural migration are that it does not require estimation of the near-surface velocity or modeling of elastic waves. In addition, natural migration simultaneously images both low- and higher-order scattering and mode converted waves. The disadvantage is that the image resolution is dependent on the distribution of seismic receivers. To validate this concept, natural migration is applied to crosscorrelograms of passive data recorded by the Long Beach array and the USArray. The resulting migration images highlight known discontinuities from tomography and correlate to prominent geological boundaries at two very different scales: (1) tectonic scale such as the edge of the Atlantic Plain Province in southeastern US and (2) regional scale structure in Long Beach, California. The migration images can be used along with tomography methods to improve structure sharpness in a model construction.

  1. Imaging the Yellowstone Magmatic System Using Multi-Component Ambient Noise Cross-Correlation and Tomography

    Science.gov (United States)

    Farrell, J.; Lin, F. C.

    2015-12-01

    We present a new S-wave velocity model for the Yellowstone magmatic system derived from the inversion of Rayleigh- and Love-wave phase velocity measurements from periods from 6 to 35 s. All available data from 2007-2014 within and near the Yellowstone region was downloaded for the USArray TA network (TA), the Yellowstone Seismic Network (WY), the NOISY array (Z2), the USGS Intermountain West network (IW), the Plate Boundary Observatory Borehole Seismic Network (PB), and the USGS National Seismic Network (US). For each station, we perform daily noise pre-processing (temporal normalization and spectrum whitening) simultaneously for all three components before multi-component noise cross-correlations are calculated. Results for both Rayleigh- and Love-wave phase velocity inversions clearly show the low velocity anomaly associated with the upper-crustal magma reservoir seen previously using body wave tomography. In addition, low-velocity anomalies associated with sediment-filled basins are visible in Wyoming. Short period low Love-wave velocities are seen along the Snake River Plain, the track of the Yellowstone hotspot likely related to the shallow sediment layer. Based on the surface wave phase velocity maps, we invert for a 3D S-wave crustal model. The resulting model will be compared to previous, but spatially limited, body wave S-wave models as well as recent body wave P-wave velocity models to better constrain Vp/Vs ratios as well as the melt fraction of the magma chamber. Preliminary results using amplitude information of noise cross-correlations to calculate Rayleigh-wave ellipticity, or Rayleigh-wave H/V (horizontal to vertical) amplitude ratios to better constrain the shallow velocity structure will also be discussed.

  2. Seismic ambient noise H/V spectral ratio using the ACA (autocorrelations of coda of autocorrelations) approach

    Science.gov (United States)

    Sanchez-Sesma, F. J.; Piña, J.; Campillo, M.; Luzón, F.; García-Jerez, A.; Albarello, D.; Lunedei, E.

    2012-12-01

    The seismic ambient noise horizontal-to-vertical spectral ratios (NHVSR) are valuable for microzonation, and seismic prospecting. This is particularly true for low-cost dense spatial sampling projects. Arai and Tokimatsu (2004) proposed to use average energy densities to compose the ratios. It means that H/V comes from the square root of the ratio of averages. On the other hand, a popular approach makes the average of spectral ratios. For ergodic processes peak values are usually the same using these two approaches. Sometimes however, the observations are insufficient and computed values for low frequencies display large variability and the corresponding H/V estimates may be inaccurate. The bias caused by localized sources may be the source of errors in the estimates. In this work we propose to compute the NHVSR using the Autocorrelations of Coda of Autocorrelations. This ACA approach is inspired in the work by Stehly et al. (2008). They used the Correlations of Coda of Correlations (C3) to isotropize the field. In our ACA approach the whole time series, say of 30 minutes, for each component is autocorrelated and the averages of the spectral density of selected windows (late coda windows are eliminated) are then improved estimates of directional energy densities. The computation of NHVSR using ACA appears more stable and free of transient effects. It remains to establish how this may be accounted for in forward calculation of H/V spectral ratios for models like a layered medium (e.g. Sánchez-Sesma et al., 2011; Albarello and Lunedei, 2011). This will require further scrutiny. References. Albarello, D. & E. Lunedei (2011). Structure of ambient vibration wavefield in the frequency range of engineering interest ([0.5, 20] Hz): insights from numerical modelling. Near Surface Geophysics 9, 543-559. Arai, H. & K. Tokimatsu (2004). S-wave velocity profiling by inversion of microtremor H/V spectrum, Bull. Seismol. Soc. Am. 94, 53-63. Sánchez-Sesma, F. J., M. Rodr

  3. A 3D Seismic Velocity Model Offshore Southern California from Ambient Noise Tomography of the ALBACORE OBS Array

    Science.gov (United States)

    Kohler, M. D.; Bowden, D. C.; Tsai, V. C.; Weeraratne, D. S.

    2015-12-01

    The Pacific-North America plate boundary in Southern California extends far west of the coastline, and a 12-month ocean bottom seismometer (OBS) array spanned the western side of the plate boundary to image lithospheric seismic velocities. Velocities are modeled through stacked cross correlations of ambient noise data. Twelve months of continuous data were used from 22 OBS stations and ~30 coastal and island Southern California Seismic Network stations. Particular attention has been paid to improving signal-to-noise ratios in the noise correlations with OBS stations by removing the effects of instrument tilt and infragravity waves. Different applications of preprocessing techniques allow us to distinguish the fundamental and first higher order Rayleigh modes, especially in deep water OBS pairs where the water layer dominates crustal sensitivity of the fundamental mode. Standard time domain and frequency domain methods are used to examine surface wave dispersion curves for group and phase velocities between 5 and 50 second periods, and these are inverted for 3D velocity structure. The results define the transition in three dimensions from continental lithospheric structure in the near-shore region to oceanic structure west of the continental borderland. While the most prominent features of the model relate to thinning of the crust west of the Patton Escarpment, other notable anomalies are present north-to-south throughout the continental borderland and along the coast from the Los Angeles Basin to the Peninsular Ranges. The velocity model will help describe the region's tectonic history, as well as provide new constraints for determination of earthquake relocations and rupture styles.

  4. Validation of S-wave Velocity beneath the Ise Bay, Central Japan, Using Continuous Short-period Ambient Noise Data

    Science.gov (United States)

    Hayashida, T.; Yoshimi, M.; Horikawa, H.

    2014-12-01

    We have applied seismic interferometry to three-component ambient noise data recorded around the Ise bay area, central Japan, to validate published three-dimensional S-wave velocity models. For the bay area, detailed seismic velocity structure models have been constructed based on P-wave reflection surveys. There is no direct information on the S-wave velocities beneath the bay and the parameters are assigned by reference to those in a land area. We used one-year continuous data from 20 permanent stations of the NIED Hi-net (High-sensitivity seismograph network) to obtain stacked cross-correlation functions (CCFs) of ambient noise between station pairs that cross the bay. The CCFs were calculated, using one-hour data in the radial-radial (R-R), transverse-transverse (T-T) and vertical-vertical (Z-Z) directions for time lags of ±500s. Horizontal distances between the stations range form 15 km to 103 km. Although the Hi-net stations deploy seismometers with the natural period of 1 s, we found that the yearly stacked CCFs for selected 101 Hi-net station pairs are comparable with those derived from neighboring broadband seismic stations in the frequency range between 0.1 and 0.5 Hz, by deconvolving the instrument response. The CCFs shows clear Rayleigh waves from all directions in the R-R and Z-Z components, and clear Love waves in the T-T component with reasonable signal-to-noise ratios. The derived group velocities and waveforms of the wave trains are variable in the higher frequency range (> 0.2 Hz), indicating deep sedimentary basin beneath the bay. We compared obtained group velocities with theoretical ones to find systematic differences between the expected structure model from the CCFs and the published models in the northwest part of the bay, while the agreements are generally good for many other station pairs. This result indicates that the seismic interferometry technique provides valuable information for validation and improvement of a velocity structure

  5. 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 ...

  6. Surface-wave array tomography in SE Tibet from ambient seismic noise and two-station analysis: I - Phase velocity maps

    NARCIS (Netherlands)

    Yao, H.; Hilst, R.D. van der; Hoop, M.V. de

    2006-01-01

    Empirical Green’s functions (EGFs) between pairs of seismographs can be estimated from the time derivative of the long-time cross-correlation of ambient seismic noise. These EGFs reveal velocity dispersion at relatively short periods, which can be used to resolve structures in the crust and uppermos

  7. Comparison of Ambient Noise From Two Station Designs, Evaluating USArray's Transportable and Flexible Arrays in the Pacific Northwest

    Science.gov (United States)

    Pfeifer, M.; Alvarez, M.; Woodward, R.; Yang, Z.

    2009-12-01

    ambient noise level? Both vault systems are designed to minimize noise from either cultural, electronic or environmental sources. In the case for the TA vault, a 2 meter deep hole is dug using heavy excavation equipment with over a square meter of concrete used for a base and Earth coupling. A deeper vault is known to reduce the diurnal temperature fluctuations that are a major source of noise for the broadband sensor. The standard FA vault is typically less than 1 meter deep dug by hand with approximately 1/10 square meter of concrete as a base. The construction materials and the seismic equipment for both these vaults are otherwise equivalent. We propose the following explanation for the difference in noise levels as a function of frequency and sensor component. The deeper TA vault is more stable with respect tilt which reduces the diurnal and seasonal temperature changes resulting in quieter horizontal data. The general location of TA stations near cultural noise sources such as roadways and population centers contribute to the elevated high frequency noise as compared to FA stations that are often located in very remote locations.

  8. Monitoring southwest Greenland’s ice sheet melt with ambient seismic noise

    Science.gov (United States)

    Mordret, Aurélien; Mikesell, T. Dylan; Harig, Christopher; Lipovsky, Bradley P.; Prieto, Germán A.

    2016-01-01

    The Greenland ice sheet presently accounts for ~70% of global ice sheet mass loss. Because this mass loss is associated with sea-level rise at a rate of 0.7 mm/year, the development of improved monitoring techniques to observe ongoing changes in ice sheet mass balance is of paramount concern. Spaceborne mass balance techniques are commonly used; however, they are inadequate for many purposes because of their low spatial and/or temporal resolution. We demonstrate that small variations in seismic wave speed in Earth’s crust, as measured with the correlation of seismic noise, may be used to infer seasonal ice sheet mass balance. Seasonal loading and unloading of glacial mass induces strain in the crust, and these strains then result in seismic velocity changes due to poroelastic processes. Our method provides a new and independent way of monitoring (in near real time) ice sheet mass balance, yielding new constraints on ice sheet evolution and its contribution to global sea-level changes. An increased number of seismic stations in the vicinity of ice sheets will enhance our ability to create detailed space-time records of ice mass variations. PMID:27386524

  9. Evaluating models of the US Continental Crust using Ambient Noise Datasets: A Transdimensional Approach

    Science.gov (United States)

    Olugboji, T. M.; Lekic, V.; Gao, C.; McDonough, W. F.

    2015-12-01

    Seismological information on crustal structure, when combined with other geophysical, petrological and geochemical constraints, provides our best insight into the structure and composition of Earth's continental crust. Traditionally, published models of the continental crust (e.g. Vp profiles) constrained by seismic reflection, refraction experiments and (or) receiver functions are used to infer the thickness and lithology of the upper, middle, and lower crust. In order to be most useful, however, inferences of crustal structure and composition made using seismological models as data need to be presented alongside their uncertainties. Quantifying this uncertainty is the challenge. In this work, we use the transdimensional hierarchical Bayesian inverse (THBI) approach to construct phase velocity maps for surface waves (5s - 40s), while quantifying uncertainties in the phase velocities (model variance and co-variance), as well as data noise (which can affect the model results), all without having to make a-priori choices of model parameterization or regularization. We show that phase velocity maps constructed with THBI are comparable to those from linear, least-squares inversion at long wavelengths, though differences are present across length-scales. Average phase dispersion curves extracted from our maps are statistically significantly different from predictions from a selection of global and regional crustal models (e.g., CRUST1.0 and NACR14), particularly in the western USA and across major sedimentary basins. These model-data inconsistencies suggest that tectonic regionalization and averaging can introduce significant errors into the crustal models. We also preview a second stage analysis where we use the phase-dispersion curves (and their uncertainties) as data to constrain 1-D velocity profiles (with radial anisotropy) across distinct geological provinces in the continental US. We demonstrate, again using the THBI approach, the consequences of more accurate

  10. Geophysical Investigations on Malta (Central Mediterranean) using Ambient Noise: Assessing Array Performance and Influence of a Thick Low Velocity Layer.

    Science.gov (United States)

    Farrugia, D.; Paolucci, E.; D'Amico, S.; Galea, P. M.

    2014-12-01

    The use of microtremors to obtain shear wave velocity (Vs) profiles of the subsurface is becoming a widespread approach due to its various advantages. Noise measurements were carried out at four sites on Malta (Central Mediterranean). Array techniques were first tested in an area where a ≈45 m layer of soft Blue Clay (BC) overlies the harder limestone. Three array configurations (two arrays of 17 geophones in an L-shape and circle respectively and one 42 geophone array in an L-shape) were tested and processed using the f-k and two SPAC techniques: Modified and Extended SPAC. No significant difference was observed in the dispersion curve from the two short arrays despite having different shapes. However, a significant variation was observed between the dispersion curve from the long and short arrays in the low frequency part. A joint inversion, using two direct search methods, of the dispersion and the H/V curve was then used to obtain the Vs profile for the site, with most of the profiles being in agreement both in terms of velocity and depth. A study was also conducted at three other sites on Malta where hard Upper Coralline Limestone (UCL) overlies the soft BC creating a velocity inversion in the soil profile. The shape of the effective dispersion curves obtained using ESAC show both an inverse dispersive trend and normal dispersion. This shape is tentatively explained in terms of the presence of higher mode Rayleigh waves. A Genetic Algorithm approach was then used to jointly invert the H/V and Rayleigh wave dispersion curve. It was observed that the BC velocity was higher when overlain by a large thickness of UCL. This could be linked to the effective pressure caused by the hard UCL, making the BC more compact, and having a higher velocity. The theoretical implications of a prominent low-velocity layer on site amplification and the interpretation of ambient noise data are investigated and discussed.

  11. 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 th

  12. Ambient Noise Tomography of Southern California Images Dipping San Andreas-Parallel Structure and Low-Velocity Salton Trough Mantle

    Science.gov (United States)

    Barak, S.; Klemperer, S. L.; Lawrence, J. F.

    2014-12-01

    Ambient noise tomography (ANT) images the entire crust but does not depend on the spatial and temporal distribution of events. Our ANT high-resolution 3D velocity model of southern California uses 849 broadband stations, vastly more than previous studies, and four years of data, 1997-1998, 2007, and 2011, chosen to include our own broadband Salton Seismic Imaging Project, a 40-station transect across the Salton Trough, as well as other campaign stations in both Mexico and the U.S.A., and permanent stations. Our shear-wave model has 0.05° x 0.05° lateral and 1 km vertical blocks. We used the Harvard Community Velocity Model (CVM-H) as the initial model for the inversion. We show significant differences relative to the CVM-H model, especially in the lower crust and upper mantle. We observe prominent low-velocity anomalies in the upper mantle under the Salton Buttes and Cerro Prieto geothermal fields, indicating high-temperatures and possibly partial-melt. Similar low-velocity zones have been previously observed along the Gulf of California. We also observe vertical to gradually dipping lateral velocity contrasts in the lower crust under the southern part of the San Andreas Fault. The east to northeast dip may represent crustal fabric sheared by movement of the Pacific plate under the North American plate prior to the initiation of transform motion.

  13. Response of hydrothermal system to stress transients at Lassen Volcanic Center, California, inferred from seismic interferometry with ambient noise

    Science.gov (United States)

    Taira, Taka'aki; Brenguier, Florent

    2016-10-01

    Time-lapse monitoring of seismic velocity at volcanic areas can provide unique insight into the property of hydrothermal and magmatic fluids and their temporal variability. We established a quasi real-time velocity monitoring system by using seismic interferometry with ambient noise to explore the temporal evolution of velocity in the Lassen Volcanic Center, Northern California. Our monitoring system finds temporal variability of seismic velocity in response to stress changes imparted by an earthquake and by seasonal environmental changes. Dynamic stress changes from a magnitude 5.7 local earthquake induced a 0.1 % velocity reduction at a depth of about 1 km. The seismic velocity susceptibility defined as ratio of seismic velocity change to dynamic stress change is estimated to be about 0.006 MPa-1, which suggests the Lassen hydrothermal system is marked by high-pressurized hydrothermal fluid. By combining geodetic measurements, our observation shows that the long-term seismic velocity fluctuation closely tracks snow-induced vertical deformation without time delay, which is most consistent with an hydrological load model (either elastic or poroelastic response) in which surface loading drives hydrothermal fluid diffusion that leads to an increase of opening of cracks and subsequently reductions of seismic velocity. We infer that heated-hydrothermal fluid in a vapor-dominated zone at a depth of 2-4 km range is responsible for the long-term variation in seismic velocity[Figure not available: see fulltext.

  14. Inversion of ambient seismic noise HVSR to evaluate velocity and structural models of the Lower Tagus Basin, Portugal

    Science.gov (United States)

    Borges, J. F.; Silva, H. G.; Torres, R. J. G.; Caldeira, B.; Bezzeghoud, M.; Furtado, J. A.; Carvalho, J.

    2016-07-01

    During its history, several significant earthquakes have shaken the Lower Tagus Valley (Portugal). These earthquakes were destructive; some strong earthquakes were produced by large ruptures in offshore structures located southwest of the Portuguese coastline, and other moderate earthquakes were produced by local faults. In recent years, several studies have successfully obtained strong-ground motion syntheses for the Lower Tagus Valley using the finite difference method. To confirm the velocity model of this sedimentary basin obtained from geophysical and geological data, we analysed the ambient seismic noise measurements by applying the horizontal to vertical spectral ratio (HVSR) method. This study reveals the dependence of the frequency and amplitude of the low-frequency (HVSR) peaks (0.2-2 Hz) on the sediment thickness. We have obtained the depth of the Cenozoic basement along a profile transversal to the basin by the inversion of these ratios, imposing constraints from seismic reflection, boreholes, seismic sounding and gravimetric and magnetic potentials. This technique enables us to improve the existing three-dimensional model of the Lower Tagus Valley structure. The improved model will be decisive for the improvement of strong motion predictions in the earthquake hazard analysis of this highly populated basin. The methodology discussed can be applied to any other sedimentary basin.

  15. 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.

  16. New constraints on the magmatic system beneath Newberry Volcano from the analysis of active and passive source seismic data and ambient noise

    Science.gov (United States)

    Heath, Benjamin Allen

    Using joint P-wave seismic tomography, receiver functions, and ambient noise we image the magmatic structure beneath Newberry Volcano, located near Bend, Oregon. Use of active source and teleseismic events in a joint tomographic inversion provides the ray crossings necessary to resolve a low velocity body around 4 km depth. Receiver functions show large lateral heterogeneity and are consistent with the location of a low velocity body derived from the tomography but require a larger low velocity anomaly. Ambient noise autocorrelations are used to image a low velocity reflector, located at ~3 km depth, shallower than the imaged low velocity body recovered using tomography and receiver functions. Ultimately, our results reveal a magma chamber at 3-4 km depth beneath Newberry caldera, with an overlying partially molten sill at ~3 km depth. These results show the usefulness of dense seismometer deployments over volcanoes.

  17. 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

  18. Azimuthal anisotropy within the crust and uppermost mantle of southeastern China from both ambient noise and teleseismic earthquake Rayleigh wave tomography

    Science.gov (United States)

    Xie, J.; Quan, Z. L.; Lin, F.; Shen, W.; Zheng, Y.; Yang, Y.; Ritzwoller, M. H.

    2011-12-01

    The recent deployment of the Chinese Seismic Array provides the opportunity to investigate both the isotropic and anisotropic structure of southeastern China, a region that remains rather poorly studied with the latest high resolution surface wave tomography. Here we present estimates of Rayleigh waves azimuthal anisotropy obtained from ambient noise and earthquake tomography based on 2-years of data observed at 380 broad-band stations with a average spacing less than 100 km in the southeastern China. We also present a 3-D model of shear wave azimuthally anisotropy in the crust and uppermost mantle. In order to obtain reliable surface wave measurements, we first perform quality control on these stations that have been accumulated from 18 different provincial networks. There are ten different types of seismometers with five different corner frequencies ranging from periods of 20s to 360s. Using ambient noise and earthquake signals, we identify phase and amplitude response problems for stations and correct them when we can; otherwise we discard the station. With the corrected data, reliable Empirical Green's functions (EGFs) between each station pair are then obtained from the time derivative of the 2-year cross-correlation of ambient seismic noise between 8 sec and 40 sec period, totally more than 70,000 inter-station paths. In addition, about 600 earthquakes with Ms>5 are available during these two years. We apply the eikonal tomography method to the ambient noise data set and Helmholtz tomography method to the earthquake data set (25 - 50 sec period). This generates both isotropic and anisotropic dispersion maps that are sensitive to the crust and into the uppermost mantle. Using the Rayleigh wave dispersion results, local anisotropy dispersion curves are constructed and then inverted for Vsv anisotropy in the crust and uppermost mantle. The result provides insight into the tectonic connection between the rapidly deforming crust of southeastern Tibet, the stable

  19. 3D ambient noise tomography across the Taiwan Strait: the structure of a magma-poor rifted margin

    Science.gov (United States)

    Kuo-Chen, Hao; Chen, Kai-Xun; Brown, Dennis; Li, Qiusheng; Ye, Zhuo; Liang, Wen-Tzong; Wang, Chien-Ying; Yao, Huajian

    2016-04-01

    Rifting along southeastern Eurasia in the Late Cenozoic led to the formation of a magma-poor rifted margin facing the South China Sea to the southeast and the Philippine Sea to the east. Further rifting along the outer part of the margin during the Middle to Late Miocene was accompanied by an extensive episode of intraplate flood volcanism that formed the Penghu Archipelago. Previous geophysical studies in the area of the Strait have focused primarily on the shallow structures of the rift basins and the depth to the Moho. In this study, we present the results of a joint Chinese and Taiwanese 3D ambient noise tomography study from which we calculate the regional-scale 3D S-wave structure of the Taiwan Strait. The S-wave model shows a thinning of the crust beneath the rift basins where, locally, thin high-velocity layers suggest the presence of intrusive bodies. The rift basins and, along the west coast of Taiwan, the foreland basin are imaged as c. 5 to 10 km thick low velocity zones that extend eastward beneath the Taiwan mountain belt. In the upper 10 km of the crust, the basaltic rocks of the Penghu Archipelago are imaged as a high velocity zone that, with depth, becomes a relatively low velocity zone. We interpret this low velocity zone in the lower crust and upper mantle beneath the Penghu Archipelago to image a thermal anomaly related to the still cooling magma feeding system and the melt reservoir area that fed the flood basalts at the surface.

  20. Ambient noise tomography of the Cameroon Volcanic Line and Northern Congo craton: new constraints on the structure of the lithosphere

    Science.gov (United States)

    Guidarelli, M.; Aoudia, A.

    2016-03-01

    We investigate the lithospheric structure of Cameroon inverting Rayleigh waves obtained from the cross-correlation of ambient seismic noise. We correlate seismic records between 32 broad-band stations and we obtain good quality Rayleigh waves for 310 interstation paths. We measure group velocity dispersion curves from the reconstructed Rayleigh waves in the period range 10-35 s and we invert the group velocities for tomographic images. After the tomography the group velocities are then inverted, together with longer period group velocity measurements from existing literature, to compute a 3-D S-wave velocity model of the Cameroon lithosphere down to 100 km depth. Our results provide an unprecedented mapping of the physical properties of the different crustal units and their correlations with surface geology, as well as with mantle lithospheric variations. The Cameroon Volcanic Line (CVL) appears as a segmented feature exhibiting different physical properties along strike. The active Mt Cameroon volcano is underlain by very low velocities, unlike the other segments of the CVL. The along-strike variations in crustal structure suggest that lateral heterogeneities in lithospheric thickness and physical properties have influenced the location and distribution of magmatism. The crust beneath the Central African Shear Zone exhibits a sizeable low velocity anomaly. The lithosphere beneath Cameroon is characterised by a heterogeneous crust with a relatively constant thickness and a low velocity uppermost mantle at the edge of the Congo Craton. Our results favour processes combining small-scale upwelling at the edge of a thick lithosphere and reactivation of Precambrian basement structures to explain the distribution of Holocene-Recent magmatism and plateau uplift. Our results also indicate that Mt Cameroon and surroundings areas are the most at risk zones for magmatic activity during this stage of CVL development.

  1. 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

  2. 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.

  3. Preliminary Results From the CAUGHT Experiment: Investigation of the North Central Andes Subsurface Using Receiver Functions and Ambient Noise Tomography

    Science.gov (United States)

    Ryan, J. C.; Ward, K. M.; Porter, R. C.; Beck, S. L.; Zandt, G.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2011-12-01

    Altiplano and portions of the Eastern Cordillera, and at approximately 40 under the sub-Andes and westernmost edge of the Beni basin. Unlike previous studies farther south, we do not see an increased crustal thickness beneath the Eastern Cordillera. The CAUGHT station coverage is also ideal for Ambient Noise Tomography (ANT) to investigate the seismic shear wave velocities in the upper crust (McQuarrie, N., Barnes, J., and Ehlers, T.A., 2008, Geometric, kinematic and erosional history of the central Andean Plateau (15-17°S), northern Bolivia: Tectonics, v. 27, TC3007, doi:10.1029/2006TC002054.

  4. Enhanced Rayleigh waves tomography of Mexico using ambient noise cross-correlations (C1) and correlations of coda of correlations (C3)

    Science.gov (United States)

    Spica, Z. J.; Perton, M.; Calo, M.; Cordoba-Montiel, F.; Legrand, D.; Iglesias, A.

    2015-12-01

    Standard application of the seismic ambient noise tomography considers the existence of synchronous records at stations for green's functions retrieval. More recent theoretical and experimental observations showed the possibility to apply correlation of coda of noise correlation (C3) to obtain green's functions between stations of asynchronous seismic networks making possible to dramatically increase databases for imagining the Earth's interior. However, this possibility has not been fully exploited yet, and right now the data C3 are not included into tomographic inversions to refine seismic structures. Here we show for the first time how to incorporate the data of C1 and C3 to calculate dispersion maps of Rayleigh waves in the range period of 10-120s, and how the merging of these datasets improves the resolution of the structures imaged. Tomographic images are obtained for an area covering Mexico, the Gulf of Mexico and the southern U.S. We show dispersion maps calculated using both data of C1 and the complete dataset (C1+C3). The latter provide new details of the seismic structure of the region allowing a better understanding of their role on the geodynamics of the study area. The resolving power obtained in our study is several times higher than in previous studies based on ambient noise. This demonstrates the new possibilities for imaging the Earth's crust and upper mantle using this enlarged database.

  5. 3D shallow structures in the Baogutu area, Karamay, determined by eikonal tomography of short-period ambient noise surface waves

    Science.gov (United States)

    Xu, Hongrui; Luo, Yinhe; Chen, Chao; Xu, Yixian

    2016-06-01

    Eikonal tomography based on ambient noise data is one of the most effective methods to reveal shallow earth structures. By tracking surface wave phase fronts, constructing travel time surfaces, and computing the gradients of travel time surfaces to generate phase velocity maps, eikonal tomography avoids the ray tracing and matrix construction and inversion in the traditional surface wave tomography methods. In this study, we collect continuous ambient noise data recorded by a dense seismic array in Karamay, Xinjiang to construct a 3D model of shallow structures using eikonal tomography. The seismic array consists of 35 stations with shortest interstation distance close to 1 km. 890 empirical surface wave Green's functions (EGFs) between each station pair are retrieved by cross-correlating one or two months of continuous ambient noise data. From these EGFs, surface wave travel times in the frequency range of 1.8 to 4.0 Hz are measured by a frequency-time analysis technique (FTAN). Then, eikonal tomography is adopted to construct Rayleigh wave phase velocity maps and estimate the phase velocity uncertainties. Finally, we invert the obtained phase velocity dispersion curves for 1D shear velocity profiles and then assemble these 1D profiles to construct a 3D shear velocity model. Major velocity features of our 3D model are correlated well with the known geological features. A shallow east-west velocity discontinuity is observed, which clearly reflects the lithological change between Baogutu formation (C1b) and Xibeikulasi formation (C1x) of lower Carboniferous system. Low shear velocities are observed beneath the location of porphyry copper deposit (V), possibly related to stockwork fracture and hydrothermal brecciation developed during the intrusion of deep magma in forming the deposit.

  6. Resolving Rupture Directivity of Moderate Strike-Slip Earthquakes in Sparse Network with Ambient Noise Location: A Case Study with the 2011 M5.6 Oklahoma Earthquake

    Science.gov (United States)

    He, X.; Ni, S.

    2015-12-01

    Earthquake rupture directivity is essential for improving reliability of shakemap and understanding seismogenic processes by resolving the ruptured fault. Compared with field geological survey and InSAR technique, rupture directivity analysis based on seismological data provides rapid characterization of the rupture finiteness parameters or is almost the only way for resolving ruptured fault for earthquakes weaker than M5. In recent years, ambient seismic noise has been widely used in tomography and as well as earthquake location. Barmin et al. (2011) and Levshin et al. (2012) proposed to locate the epicenter by interpolating the estimated Green's functions (EGFs) determined by cross-correlation of ambient noise to arbitrary hypothetical event locations. This method does not rely on an earth model, but it requires a dense local array. Zhan et al. (2011) and Zeng et al. (2014) used the EGFs between a nearby station and remote stations as calibration for 3D velocity structure and then obtained the centroid location. In contrast, the hypocenter can be determined by P wave onsets. When assuming unilateral rupture, we can resolve the rupture directivity with relative location of the centroid location and hypocenter. We apply this method to the 2011 M5.6 Oklahoma earthquake. One M4.8 foreshock and one M4+ aftershock are chosen as reference event to calibrate the systematic bias of ambient noise location. The resolved rupture plane strikes southwest-northeast, consistent with the spatial distribution of aftershocks (McNamara et al., 2015) and finite fault inversion result (Sun et al., 2014). This method works for unilaterally ruptured strike-slip earthquakes, and more case studies are needed to test its effectiveness.

  7. Dynamic characteristics of a coastal area of lateral spreading using ambient noise time series - Anchor Bay, Malta

    Science.gov (United States)

    Galea, Pauline; D'Amico, Sebastiano; Farrugia, Daniela

    2013-04-01

    Anchor Bay and surrounding regions are located on the northwest coast of the island of Malta, Central Mediterranean. The area is characterized by a coastal cliff environment having an outcropping layer of hard coralline limestone (UCL) resting on a thick (up to 50m) layer of clays and marls (Blue Clay, BC). This configuration gives rise to a number of processes leading to coastal instability, in particular lateral spreading phenomena and rock falls. Previous and ongoing studies have identified both lateral spreading rates and vertical motions of up to 27mm per year (Mantovani et al, 2012). The area is an interesting natural laboratory as coastal detachment processes in a number of different stages can be identified and are easily accessible. We investigate the site dynamic characteristics of this study area by recording ambient noise time series (20 minutes long) at over 20 points, over an area of 0.07 km2, using a portable 3-component seismograph (Tromino ) The time series are processed to give both horizontal-to-vertical spectral ratio graphs (HVSR) as well as frequency-dependent polarisation analysis as proposed by Burjanek (2011, 2012). The HVSR graphs illustrate and quantify aspects of site resonance effects due both to underlying geology as well as to mechanical resonance of partly or wholly detached boulders or blocks. The polarization diagrams indicate predominant directions of vibrational effects. Results from this study show an unambiguous distinction between the behavior of "stable" areas, away from the cliff edges, the region of the unstable cliff edge and the actual rockfall areas. Stable regions are characterized by a single and pronounced HVSR resonance peak at around 1.5Hz that are characteristic of all other areas in the Maltese islands having the same underlying geological sequence, while HVSR curves closer to the cliff edge show more complex responses at higher frequencies characteristic of the dynamic behavior of individual detached blocks

  8. 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.

  9. Qualificação e quantificação da exposição sonora ambiental em uma unidade de terapia intensiva geral Qualification and quantification of ambient noise exposure in a general intensive care unit

    Directory of Open Access Journals (Sweden)

    Raquel Paganini Pereira

    2003-12-01

    Full Text Available Os níveis de ruído hospitalares encontram-se excessivamente elevados, especialmente no ambiente de UTI, em decorrência dos inúmeros alarmes e equipamentos, além da conversação da própria equipe hospitalar. Diante disso, esse ambiente, que deveria ser silencioso e tranqüilo, torna-se ruidoso, transformando-se em um grande fator de estresse e podendo gerar distúrbios fisiológicos e psicológicos tanto nos pacientes como nos funcionários dessa unidade. OBJETIVO: O objetivo deste estudo foi verificar o nível de pressão sonora equivalente em uma UTI geral, procurando estabelecer o período de maior exposição e comparando os resultados com as recomendações nacionais e internacionais. FORMA DE ESTUDO: Estudo observacional. MATERIAL E MÉTODO: Medição do ruído ambiental da UTI do Hospital São Paulo através do analisador de ruído modelo 2260 (Brüel & Kjaer, em período total de 6.000 minutos e aferições a cada 27 segundos, configurado da seguinte forma: tempo de resposta rápido (Fast, medindo em decibel o nível de pressão sonora e usando a ponderação em freqüência A, de setembro de 2001 a junho de 2002 e sem o conhecimento dos funcionários do setor. RESULTADOS: O nível de pressão sonora equivalente (Leq apresentou média de 65,36 dB(A variando de 62,9 a 69,3 dB(A. Durante o período diurno a média do Leq foi de 65,23 dB(A e para o período noturno, 63,89 dB(A. O L FMax encontrado foi de 108,4 dB(A e o L FMin de 40 dB(A. CONCLUSÕES: O nível de ruído encontrado nessa UTI está acima do recomendado pela literatura em todos os períodos analisados. Dessa forma, as fontes produtoras de ruído excessivo precisam ser melhor identificadas para que possam ser tomadas as devidas medidas para atenuação desse ruído e tornar esse ambiente um local mais silencioso, beneficiando a função laborativa dos profissionais e a recuperação dos pacientes.Noise levels in hospitals are excessively high, especially in the ICU

  10. A methodological approach towards high-resolution surface wave imaging of the San Jacinto Fault Zone using ambient-noise recordings at a spatially dense array

    Science.gov (United States)

    Roux, Philippe; Moreau, Ludovic; Lecointre, Albanne; Hillers, Gregor; Campillo, Michel; Ben-Zion, Yehuda; Zigone, Dimitri; Vernon, Frank

    2016-08-01

    We present a new technique for deriving detailed information on seismic velocities of the subsurface material from continuous ambient noise recorded by spatially dense seismic arrays. This method uses iterative double beamforming between various subarrays to extract surface wave contributions from the ambient-noise data in complex environments with unfavourable noise-source distributions. The iterative double beamforming extraction makes it possible to retrieve large amounts of Rayleigh wave traveltime information in a wide frequency band. The method is applied to data recorded by a highly dense Nodal array with 1108 vertical geophones, centred on the damage zone of the Clark branch of the San Jacinto Fault Zone south of Anza, California. The array covers a region of ˜650 × 700 m2, with instrument spacing of 10-30 m, and continuous recording at 500 samples s-1 over 30 d in 2014. Using this iterative double beamforming on subarrays of 25 sensors and cross-correlations between all of the station pairs, we separate surface waves from body waves that are abundant in the raw cross-correlation data. Focusing solely on surface waves, maps of traveltimes are obtained at different frequencies with unprecedented accuracy at each point of a 15-m-spacing grid. Group velocity inversions at 2-4 Hz reveal depth and lateral variations in the structural properties within and around the San Jacinto Fault Zone in the study area. This method can be used over wider frequency ranges and can be combined with other imaging techniques, such as eikonal tomography, to provide unprecedented detailed structural images of the subsurface material.

  11. A system for ocean ambient noise measurement based on subsurface buoy%基于潜标的海洋环境噪声测量系统

    Institute of Scientific and Technical Information of China (English)

    吕云飞; 张殿伦; 邹吉武; 兰华林; 孙大军

    2009-01-01

    This paper aims to design the system of ocean ambient noise measurement, the system is deployed with subsurface buoy, low frequency ambient noise of shallow water is measured by vector hydrophone. Vector hydrophone measures pressure and all three orthogonal components of particle velocity at a single point in space,the measured signal is preprocessed and sampled, the sampled data can be self-stored in subsurface buoy or transmitted to shore station by buoy. The method of noise measurement is discussed, the results of the sea trials show that the system is feasible and reliable.%对海洋环境噪声测量系统技术进行了研究,设计和实现了一种基于潜标的海洋环境噪声测量系统,并进行了海上试验.该系统采用潜标的布放方式,利用矢量水听器测量浅海海洋环境噪声场的低频噪声.矢量水听器同步测量声场空间一点处的声压和质点振速三个正交分量, 测量信号经预处理后,对信号进行数模变换,得到的噪声数据可以在潜标中自记录或通过水面浮标传输到岸站存储.对噪声测量方法进行的分析和海上试验的结果表明,该系统稳定可靠,能正确地拾取海洋环境噪声.

  12. Your attention please: increasing ambient noise levels elicits a change in communication behaviour in humpback whales (Megaptera novaeangliae).

    Science.gov (United States)

    Dunlop, Rebecca A; Cato, Douglas H; Noad, Michael J

    2010-08-22

    High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background noise. Humpback whale communication signals comprise two different types: vocal signals, and surface-generated signals such as 'breaching' or 'pectoral slapping'. We found that humpback whales gradually switched from primarily vocal to primarily surface-generated communication in increasing wind speeds and background noise levels, though kept both signal types in their repertoire. Vocal signals have the advantage of having higher information content but may have the disadvantage of loosing this information in a noisy environment. Surface-generated sounds have energy distributed over a greater frequency range and may be less likely to become confused in periods of high wind-generated noise but have less information content when compared with vocal sounds. Therefore, surface-generated sounds may improve detection or enhance the perception of vocal signals in a noisy environment. PMID:20392731

  13. Your attention please: increasing ambient noise levels elicits a change in communication behaviour in humpback whales (Megaptera novaeangliae)

    OpenAIRE

    Dunlop, Rebecca A.; Cato, Douglas H.; Noad, Michael J.

    2010-01-01

    High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background ...

  14. Thermal conductivity of silver loaded conductive epoxy from cryogenic to ambient temperature and its application for precision cryogenic noise measurements

    Science.gov (United States)

    Amils, Ricardo I.; Gallego, Juan Daniel; Sebastián, José Luis; Muñoz, Sagrario; Martín, Agustín; Leuther, Arnulf

    2016-06-01

    The pressure to increase the sensitivity of instrumentation has pushed the use of cryogenic Low Noise Amplifier (LNA) technology into a growing number of fields. These areas range from radio astronomy and deep space communications to fundamental physics. In this context manufacturing for cryogenic environments requires a proper thermal knowledge of the materials to be able to achieve adequate design behavior. In this work, we present experimental measurements of the thermal conductivity of a silver filled conductive epoxy (EPO-TEK H20E) which is widely used in cryogenic electronics applications. The characterization has been made using a sample preparation which mimics the practical use of this adhesive in the fabrication of cryogenic devices. We apply the data obtained to a detailed analysis of the effects of the conductive epoxy in a monolithic thermal noise source used for high accuracy cryogenic microwave noise measurements. In this application the epoxy plays a fundamental role since its limited thermal conductivity allows heating the chip with relatively low power. To our knowledge, the cryogenic thermal conductivity data of this epoxy has not been reported before in the literature in the 4-300 K temperature range. A second non-conductive epoxy (Gray Scotch-Weld 2216 B/A), also widely used in cryogenic applications, has been measured in order to validate the method by comparing with previous published data.

  15. Shallow Velocity Structure of Tapachula Town (chiapas, Mexico) from Joint Inversion of Array and H/v Spectral Ratio of Ambient Noise

    Science.gov (United States)

    Navarro, M.; Vidal, F.; García-Jerez, A.; Alguacil, G.; Ruíz-Sibaja, A.; Aguirre, J.; Cárdenas, R.

    2013-05-01

    The shallow geological structure of Tapachula town has been estimated applying an association of the spatial autocorrelation (SPAC) method and the horizontal-to-vertical spectral ratio (HVSR, Nakamura 1989) method for ambient noise. Regular pentagonal arrays with radii up to 24 m have been employed for velocity computation. The measurements were carried out at six open spaces. Vertical components of ground motion, excited by ambient noise, were recorded at the surface. Five high-sensitivity sensors surrounding a sixth central sensor with same characteristics were used. All the records were analysed by using an implementation of the SPAC method (Aki, 1957). The phase-velocity of the Rg-wave was computed for each frequency from the correlation coefficient. The frequencies of the obtained curves ranged from 2.7 to 16.5 Hz and the phase velocity values varied between 226 and 594 m s-1. Nakamura's method was applied to determine the ground predominant period in the center of such arrays. The predominant period values vary in the 0.2-0.8 s range. Inversions of the S-wave velocity profiles corresponding to the six array sites have been achieved by using dispersion curves derived from SPAC and HVSR shapes. In order to classify the top shallow structure of Tapachula town, following the characterization of site adopted in several seismic codes (e.g. NEHRP 1994, Eurocode-8), the average shear-wave velocity of the upper 30 m (VS30) has been calculated. The results show differences between central part of the town and the peripheral zones close to both rivers rounding the city.

  16. Comparison of ground truth location of earthquake from InSAR and from ambient seismic noise: A case study of the 1998 Zhangbei earthquake

    Science.gov (United States)

    Xie, Jun; Zeng, Xiangfang; Chen, Weiwen; Zhan, Zhongwen

    2011-04-01

    Because ambient seismic noise provides estimated Green's function (EGF) between two sites with high accuracy, Rayleigh wave propagation along the path connecting the two sites is well resolved. Therefore, earthquakes which are close to one seismic station can be well located with calibration extracting from EGF. We test two algorithms in locating the 1998 Zhangbei earthquake, one algorithm is waveform-based, and the other is traveltime-based. We first compute EGF between station ZHB (a station about 40 km away from the epicenter) and five IC/IRIS stations. With the waveform-based approach, we calculate 1D synthetic single-force Green's functions between ZHB and other four stations, and obtain traveltime corrections by correlating synthetic Green's functions with EGFs in period band of 10-30 s. Then we locate the earthquake by minimizing the differential travel times between observed earthquake waveform and the 1D synthetic earthquake waveforms computed with focal mechanism provided by Global CMT after traveltime correction from EGFs. This waveform-based approach yields a location which error is about 13 km away from the location observed with InSAR. With the traveltime-based approach, we begin with measuring group velocity from EGFs as well as group arrival time on observed earthquake waveforms, and then locate the earthquake by minimizing the difference between observed group arrival time and arrival time measured on EGFs. This traveltime-based approach yields accuracy of 3 km, Therefore it is feasible to achieve GT5 (ground truth location with accuracy 5 km) with ambient seismic noises. The less accuracy of the waveform-based approach was mainly caused by uncertainty of focal mechanism.

  17. Small-Scale Trial for Evaluating Directional Resolution of Single Spherical Biconcave Acoustic Lens in Designing of Ambient Noise Imaging System

    Science.gov (United States)

    Mori, Kazuyoshi; Ogasawara, Hanako; Nakamura, Toshiaki

    2008-05-01

    Ambient noise imaging (ANI) is the revolutionary idea of detecting objects by using natural ocean background noise. From the analysis results obtained by the finite difference time domain (FDTD) method in our previous studies, it was supposed that a spherical biconcave lens with an aperture diameter of 2.0 m has a sufficient directional resolution (for example, the beam width is 1° at 60 kHz) for realizing an ANI system. In this study, to confirm the analysis results, we performed a small-scale trial of one-fifth space in a water tank. The lens, made of acrylic resin, has an aperture diameter of 400 mm and a radius of curvature of 500 mm. A burst pulse of 25 cycles at 300 kHz, whose frequency increases 5 times, was radiated from the sound source. The sound pressure after passage through the acoustic lens was measured by moving the receiver around the image point. Results show that the shapes of -3 dB areas are similar to the FDTD analysis results at small incidence angles. It was verified that this lens has a sufficient directional resolution for use in the ANI system, because -3 dB areas do not overlap each other.

  18. NOISE REGULATION

    OpenAIRE

    Cristina Voican; Constantin Stanescu

    2012-01-01

    Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. After the watershed passage of the United States Noise Control Act of 1972, other local and state governments passed further regulations. Although the UK and Japan enacted national laws in 1960 and 1967 respectively, these laws were not at all comprehensive or fully enforceable as to address generally rising ambient noise, enforceable...

  19. Ambiente urbano e percepção da poluição sonora Urban environment and perception to noise pollution

    Directory of Open Access Journals (Sweden)

    Adriana Bender Moreira de Lacerda

    2005-12-01

    Full Text Available A presente pesquisa avaliou a percepção da população de uma grande cidade em relação à poluição sonora (ruído urbano. Buscou-se identificar quais fontes sonoras são percebidas com maior freqüência pela população e quais reações psico-sociais relacionadas ao ruído urbano são identificados por ela. Foi utilizado um questionário composto de questões fechadas, abrangendo aspectos demográficos e aspectos psico-sociais referentes ao ruído ambiental. Oitocentos e noventa e dois (892 indivíduos participaram da pesquisa. As principais fontes de ruído citadas pelos moradores como causadoras de incômodo foram: 1 o tráfego de veículos (67 %, 2 os vizinhos (33%, 3 o barulho de sirenes (23%, 4 o barulho de animais (21% e 5 o barulho gerado pela construção civil (21 %. As principais reações psico-sociais foram: 1 irritabilidade (55%, 2 baixa concentração (28%, 3 insônia (20% e 4 dor de cabeça (19%. Os resultados obtidos coincidem com dados obtidos em pesquisas desenvolvidas na Europa, EUA e no Brasil, de que a poluição sonora ambiental influencia a qualidade de vida da população, gerando reações psico-sociais importantes, como: 1 irritabilidade e 2 insônia. Estes podem estar na base de outras doenças (disfunções cardiovasculares, podendo interferir na saúde e no bem estar dos indivíduos em particular e de uma população urbana como um todo, gerando um problema de saúde pública.The present study investigated the psychosocial complaints related to urban noise among the population of Curitiba. We used a questionnaire of closed-set questions to collect data on demographics and psychosocial reactions to environmental noise when subjects are at home. Eight hundred and ninety-two individuals (892 participated of the study. The main noise sources associated with discomfort or annoyance were traffic noise (67%, neighbors (33%, sirens (23%, animals (21%, and construction (21%. The main psychosocial complaints were

  20. 3D-ambient noise Rayleigh wave tomography of Snæfellsjökull volcano, Iceland

    Science.gov (United States)

    Obermann, Anne; Lupi, Matteo; Mordret, Aurélien; Jakobsdóttir, Steinunn S.; Miller, Stephen A.

    2016-05-01

    From May to September 2013, 21 seismic stations were deployed around the Snæfellsjökull volcano, Iceland. We cross-correlate the five months of seismic noise and measure the Rayleigh wave group velocity dispersion curves to gain more information about the geological structure of the Snæfellsjökull volcano. In particular, we investigate the occurrence of seismic wave anomalies in the first 6 km of crust. We regionalize the group velocity dispersion curves into 2-D velocity maps between 0.9 and 4.8 s. With a neighborhood algorithm we then locally invert the velocity maps to obtain accurate shear-velocity models down to 6 km depth. Our study highlights three seismic wave anomalies. The deepest, located between approximately 3.3 and 5.5 km depth, is a high velocity anomaly, possibly representing a solidified magma chamber. The second anomaly is also a high velocity anomaly east of the central volcano that starts at the surface and reaches approximately 2.5 km depth. It may represent a gabbroic intrusion or a dense swarm of inclined magmatic sheets (similar to the dike swarms found in the ophiolites), typical of Icelandic volcanic systems. The third anomaly is a low velocity anomaly extending up to 1.5 km depth. This anomaly, located directly below the volcanic edifice, may be interpreted either as a shallow magmatic reservoir (typical of Icelandic central volcanoes), or alternatively as a shallow hydrothermal system developed above the cooling magmatic reservoir.

  1. Low shear velocity in a normal fault system imaged by ambient noise cross correlation: The case of the Irpinia fault zone, Southern Italy

    Science.gov (United States)

    Vassallo, Maurizio; Festa, Gaetano; Bobbio, Antonella; Serra, Marcello

    2016-06-01

    We extracted the Green's functions from cross correlation of ambient noise recorded at broadband stations located across the Apennine belt, Southern Italy. Continuous records at 26 seismic stations acquired for 3 years were analyzed. We found the emergence of surface waves in the whole range of the investigated distances (10-140 km) with energy confined in the frequency band 0.04-0.09 Hz. This phase reproduces Rayleigh waves generated by earthquakes in the same frequency range. Arrival time of Rayleigh waves was picked at all the couples of stations to obtain the average group velocity along the path connecting the two stations. The picks were inverted in separated frequency bands to get group velocity maps then used to obtain an S wave velocity model. Penetration depth of the model ranges between 12 and 25 km, depending on the velocity values and on the depth of the interfaces, here associated to strong velocity gradients. We found a low-velocity anomaly in the region bounded by the two main faults that generated the 1980, M 6.9 Irpinia earthquake. A second anomaly was retrieved in the southeast part of the region and can be ascribed to a reminiscence of the Adria slab under the Apennine Chain.

  2. Crustal and upper mantle S-wave velocity structures across the Taiwan Strait from ambient seismic noise and teleseismic Rayleigh wave analyses

    Science.gov (United States)

    Huang, Y.; Yao, H.; Wu, F. T.; Liang, W.; Huang, B.; Lin, C.; Wen, K.

    2013-12-01

    Although orogeny seems to have stopped in western Taiwan large and small earthquakes do occur in the Taiwan Strait. Limited studies have focused on this region before and were barely within reach for comprehensive projects like TAICRUST and TAIGER for logistical reasons; thus, the overall crustal structures of the Taiwan Strait remain unknown. Time domain empirical Green's function (TDEGF) from ambient seismic noise to determine crustal velocity structure allows us to study an area using station pairs on its periphery. This research aims to resolve 1-D average crustal and upper mantle S-wave velocity (Vs) structures alone paths of several broadband station-pairs across the Taiwan Strait; 5-120 s Rayleigh wave phase velocity dispersion data derived by combining TDEGF and traditional surface wave two-station method (TS). The average Vs structures show significant differences in the upper 15 km as expected. In general, the highest Vs are observed in the coastal area of Mainland China and the lowest Vs appear along the southwest offshore of the Taiwan Island; they differ by about 0.6-1.1 km/s. For different parts of the Strait, the Vs are lower in the middle by about 0.1-0.2 km/s relative to those in the northern and southern parts. The overall crustal thickness is approximately 30 km, much thinner and less variable than under the Taiwan Island.

  3. Imaging hydrothermal systems associated with oceanic ridge: ambient noise and travel-time tomographies in the Reykjanes high-temperature area, SW-Iceland.

    Science.gov (United States)

    Jousset, Philippe; Ágústsson, Kristjan; Verdel, Arie; Blanck, Hanna; Franke, Steven; Specht, Sebastian; Stefánsson, Stefán; Tryggvason, Hörður; Erbas, Kemal; Deon, Fiorenza; Erlendsson, Ögmundur; Guðnason, Egill; Hersir, Gylfi; Ryberg, Trond; Halldórsdóttir, Sæunn; Weemstra, Cornelius; Bruhn, David; Flovenz, Ólafur; Friðleifsson, Ómar

    2015-04-01

    Analogue outcrops of hydrothermal fossil systems and simulating pressure/temperature conditions in the laboratory are classical methods for assessing supercritical conditions in magmatic environments. Scientific drilling is used when Earth surface sampled rocks cannot sufficiently explain past geological processes and when geophysical imaging does not sufficiently explain observed phenomena. However, our understanding of structural and dynamic characteristics of geothermal systems can be improved through application of advanced and/or innovative exploration technologies. Unlike resistivity imaging, active and passive seismic techniques have rarely been used in volcanic geothermal areas, because processing techniques were not adapted to geothermal conditions. Recent advances in volcano-seismology have introduced new processing techniques for assessing subsurface structures and controls on fluid flow in geothermal systems. We present here preliminary analyses of seismic records around a geothermal reservoir located both on-land and offshore along the Reykjanes Ridge, SW-Iceland. We deployed 214 on-land stations and 24 Ocean Bottom Seismometers since April 2014. We analyse more than 6 months of part of those records. We present first results of both travel-time tomography and ambient noise tomography and we discuss briefly implications for geothermal exploration in volcanic contexts.

  4. Seasonal changes of the ambient noise recorded by the "13 BB star" array in northern Poland within the Trans European Suture Zone

    Science.gov (United States)

    Lepore, Simone; Grad, Marek

    2016-04-01

    The variations in the azimuth of ambient noise sources, as well as the coherence of the average velocity of surface waves arrivals, were evaluated by applying beam forming and seismic interferometry techniques to the recordings carried out during 2014 at the "13 BB star" array composed of thirteen broadband seismic stations located in northern Poland within the Trans European Suture Zone. The evaluation of the beam power for the whole array each five days for the horizontal and vertical components led to the estimation of the azimuth variation of noise sources during the entire 2014. Fifty days represent a reasonable period to observe seasonal variations of the azimuth in time. The analysis of the azimuths makes evident the strongest beam power associated to noise does not show a preferred direction. The azimuth is predominantly fluctuating between the North Sea and the Baltic Sea: nevertheless, secondary sources like the Atlantic Sea, the Mediterranean Sea and the Black Sea were also noticed. To put in evidence the seasonal variations, the amplitude associated to the principal source was evaluated for the three components. It shows high values in January, March, April, July, August and November, whereas it is low in the remaining months. The analysis of the crosscorrelation between all the station pairs, obtained from the stacking of daily traces for January, April and September 2014 in the 0.1 1 Hz frequency band, allowed the estimation of precise values of velocities of surface waves. The best resolution to retrieve the surface waves is achieved in April, whereas in January and September several higher modes are still present in the traces. The fastest arrivals of surface waves are between ~7 s at ~20 km distance and ~40 s at ~120 km with an average velocity of ~3 km/s. The second group of arrivals is located between ~10 s at ~20 km distance and ~60 s at ~120 km: accordingly, the average velocity is ~2 km/s. The third group of arrivals, between ~13 s at 20 km

  5. S-wave velocities down to 1 km below the Peteroa volcano, Argentina, obtained from surface waves retrieved by means of ambient-noise seismic interferometry

    Science.gov (United States)

    Lepore, Simone; Gomez, Martin; Draganov, Deyan

    2015-04-01

    The main force driving the tectonics in South America is the subduction of the Nazca Plate below the South American plate. The subduction process generated numerous volcanoes in both Chile and Argentina, of which the majority is concentrated along the Chilean Argentine border. The recent explosive eruptions of some volcanoescaused concern of the population in both countries. At the beginning of 2012, a large temporary array was installed in the Malargüe region, Mendoza, Argentina, with the purpose of imaging the subsurface and monitoring the tectonic activity. The array was deployed until the end of 2012 to record continuously ambient noise and the local, regional, and global seismicity. It consisted of 38 seismic stations divided in two sub arrays, namely the PV array of six stations located on the east flank of the Peteroa volcano, and the T array of thirty two stations spread out on a plateau just north east of the town of Malargüe. Here,the focus will be on the PV array, which has a patch-like shape. Due to the intra-station distances, we chose to use for surface-wave retrieval the bands 0.8 Hz ÷ 4.0 Hz, 10 Hz ÷ 25 Hz. At the investigated area, most of the year there is little anthropogenic noise, which normally dominates frequencies above 1 Hz, meaning that the selected frequency bands can be used for surface-wave retrieval from noise. Using beamforming, we showed that for these bands, the noise is illuminating the stations from the west. This means that a correct surface-wave arrivals can be retrieved for station pairs oriented in that direction. Because of this, we used for retrieval only such station pairs. We cross-correlated the recordings on the vertical components and retrieved Rayleigh waves. By manual picking, we estimated for both bands velocity dispersion curves from the retrieved surface-wave arrivals. The curves were then inverted to obtain the velocity structure under the stations. The obtained S wave velocity depth profiles for the 10 Hz

  6. Constraints on temporal velocity variations associated with an underground gas storage in the Gulf of Valencia using earthquake and seismic ambient noise data

    Science.gov (United States)

    Ugalde, Arantza; Gaite, Beatriz; Villaseñor, Antonio

    2016-04-01

    During September 2013, the injection of the base gas in a depleted oil reservoir used as an underground natural gas storage (CASTOR) caused a sudden seismic activity increase in the eastern coast of Spain. As a result, a compact cluster of more than 550 earthquakes with magnitudes mbLg > 0.7 were located in the shallow offshore area of the Gulf of Valencia during two months. The strongest event, having a magnitude of Mw=4.2, was followed by two Mw=4.1 events the day after and took place once the gas injection activities had finished. Using the seismic data recorded by permanent stations at more than 25 km from the injection well, we applied coda wave interferometry to monitor changes in seismic velocity structure between similar earthquakes. Then we solved for a continuous function of velocity changes with time by combining observations from all the closely located earthquake sources. The rate of repeating events allowed measurements of relative velocity variations for about 30 days on a daily scale. To extend the analysis in time, we also processed the continuous data using the autocorrelation of band-pass filtered ambient seismic noise. A 10-day average was required to achieve a sufficient signal-to-noise ratio in the 0.2-0.5 Hz and 0.5-1 Hz frequency bands. We quantified the time lags between two traces in the frequency and time domains by means of the Moving Window Cross Spectral Analysis and a Dynamic Time Warping technique, respectively. Injection of fluids in geologic formations causes variations in seismic velocities associated to changes in fluid saturation, increase in pore pressure or opening or enlargement of cracks due to the injection process. Time delays associated with stress changes caused by moderate to large earthquakes have also been established. In this work, we found no velocity changes during the gas injection period nor on the occasion of the Mw 4.2 earthquake. The sensitivity of the method is dependent on the seismic network geometry and

  7. Mechanics of underwater noise

    CERN Document Server

    Ross, Donald

    1976-01-01

    Mechanics of Underwater Noise elucidates the basic mechanisms by which noise is generated, transmitted by structures and radiated into the sea. Organized into 10 chapters, this book begins with a description of noise, decibels and levels, significance of spectra, and passive sonar equation. Subsequent chapters discuss sound waves in liquids; acoustic radiation fundamentals; wind-generated ocean ambient noise; vibration isolation and structural damping; and radiation by plate flexural vibrations. Other chapters address cavitation, propeller cavitation noise, radiation by fluctuating-force (dipo

  8. The characteristic analysis of ambient sea noise spectrum based on submersible buoy%基于潜标测量的海洋环境噪声谱特性分析

    Institute of Scientific and Technical Information of China (English)

    笪良龙; 王超; 卢晓亭; 韩梅; 邓小花

    2014-01-01

    利用海洋环境噪声测量潜标系统对南海典型海域开展了为期3个月的海洋环境噪声测量,16通道海洋环境噪声测量系统每小时测量两分钟噪声信号。数据处理结果表明,800~5000 Hz范围内,噪声谱与风速相关性最好,且风速越大相关性越好,噪声谱与风速的相关性好于与浪高的相关性。风关噪声谱级在海水中部基本不随接收深度发生变化,但由于测量水听器阵长度未能覆盖整个水深,因此未给出海面和海底处谱级变化规律。在400 Hz以上的高频段整个风速范围内噪声谱级都随风速发生变化,且噪声谱级与对数风速具有很好的线性关系。%Ambient sea-noise data were collected for three month period ,using submersible buoy system in the South China Sea .Broad-band ambient-noise signals from the sixteen hydrophones were amplified and recorded for 2min every 1h .The results of data processing show a strong wind dependence in the upper frequency bands from ap-proximately 800 Hz to 5 kHz ,and the greater the wind speed ,the better the correlation .The noise is correlated more with wind speed than with wave height . The wind-generated spectrum level producing virtually constant noise intensity in the midwater ,however ,due to the length of the hydrophone failed to cover the entire depth ,the distribution of the noise at the near-surface and near-bottom unable to given .In the frequencies above 400 Hz am-bient-noise spectrum level ranged with the entire wind speeds .In addition it was found that the ambient-noise spec-trum shown to be linearly dependent upon the logarithm of wind speed .

  9. The Structure of the Crust and Uppermost Mantle Beneath the Central Andes from Ambient Noise Tomography: Imaging the Neogene to Modern Batholith

    Science.gov (United States)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Porter, R. C.; Wagner, L. S.; Minaya, E.; Tavera, H.

    2012-12-01

    The Central Andes of southern Peru, Bolivia, and northern Chile (between ~10°S and ~35°S) comprise the largest orogenic plateau in the world associated with abundant arc volcanism, the Central Andean Plateau (CAP). The goal of this continental-scale Ambient Noise Tomography (ANT) project is to incorporate broadband seismic data from ~20 seismic networks deployed incrementally in the Central and Southern Andes from May 1994 through March 2012, to image the vertically polarized shear-wave velocity (Vsv) structure of the CAP. First-order correlations with our shallow results (~5 km) and the morphotectonic provinces as well as subtler geological features indicate our results are robust. Our major results include mapping a pervasive mid-crustal low-velocity zone (images do not resolve a high conductivity anomaly across our low-velocity zone as expected in the presence of aqueous fluids or large interconnected zones of partial melt. Therefore, we dismiss them as likely explanations for our imaged low-velocity body outside of the APVC location. Working under the hypothesis that voluminous ignimbrites are the surface expression of batholith formation at depth as exemplified by the APVC, we combine our results with the locations of known Neogene ignimbrite eruptive centers and negative isostatic residual gravity anomalies and suggest the 3.25 km/s shear-wave velocity contour at 15 km depth generally outlines the extent of a Neogene to modern batholith, with isolated pockets of partial melt where velocities dip below 3.0 km/s. A velocity of 3.25 km/s at this pressure and temperature regime is too low for an isotropic granitic composition and must be explained without invoking significant partial melt. Previous work in Tibet, a region with thick crust analogous to the CAP, suggests a zone of mid-crustal radial anisotropy may separate horizontally and vertically polarized shear-wave velocities by as much as 20%. The effective isotropic shear velocity may be ~10% faster than

  10. Inversion of H/V in layered media from seismic ambient noise based on the diffuse field theory and on improved calculation of Green functions

    Science.gov (United States)

    Sánchez-Sesma, Francisco J.; Piña, José; García-Jerez, Antonio; Luzón, Francisco; Perton, Mathieu

    2014-05-01

    The microtremor H/V spectral ratio (MHVSR) is widely used to assess the dominant frequency of soil sites. Measurements are relatively simple as only one station is needed. It has been recently proposed a theoretical basis linking ambient noise vibrations with diffuse field theory. In this theory the directional energy density computed as the average spectral density of motion at a point, is proportional to the imaginary part of Green function at the observation point. Appropriate normalization is crucial to make the experimental spectral ratios closer to the theoretical counterpart. According to this theory the square of H/V is twice the ratio ImG11 / ImG33, where ImG11 and ImG33 are the imaginary part of Green functions at the load point for horizontal and vertical components, respectively. In order to efficiently compute the imaginary part of Green's functions in a layered medium we start from an integral on the complex k plane and, using Harkrider's nomenclature, separate formulae for body-, Rayleigh-, and Love-wave components to the spectral densities are obtained. Then the poles allow for integration using the Cauchy residue theorem plus some contributions from branch integrals. It is possible to isolate pseudo reflections from ImG11 and thus constrain the inversion of soil profile. We assess ImG11 removing the influence of illumination spectrum using the H/V spectral ratio and an estimate of ImG33 (from an a priori model) by means of ImG11=0.5(H/V )2*ImG33. It has been found that ImG33 is less sensitive to details of stratigraphy. In fact, the Poisson ratio of the uppermost layer controls the slope in high frequency. With the obtained model ImG33 can be updated and the estimate of ImG11 will be improved. ACKNOWLEDGEMENTS. This research has been partially supported by DGAPA-UNAM under Project IN104712, by the MINECO research project CGL2010-16250, Spain, by the EU with FEDER, and the AXA Research Fund.

  11. 环境噪音对鸟类鸣声的影响及鸟类的适应对策%Impacts of ambient noise on bird song and adaptation strategies of birds

    Institute of Scientific and Technical Information of China (English)

    季婷; 张雁云

    2011-01-01

    For the animals living in the areas with high level ambient noise, their call signals could be overlapped with the frequency, amplitude , and temporal characters of the noise , making the spread efficiency of the animals acoustic signals decreased. Birds mainly rely on their songs for communication. The lower level spread efficiency of their acoustic signal will impact their individual recognition, mate selection, territorial defense, population density, community structure, and so on. This paper summarized the impacts of ambient noise, including urban noise and natural noise, on bird song and the adaptation strategies of birds, pointed out the concerns of these impacts in urbanization, and prospected the possible hotspots in the future research.%在高噪音环境中生存的动物,发出的声信号会与噪声的频率、振幅和时间等重叠,使动物声信号的传播效率降低.鸟类主要靠鸣声通讯,鸣声传播效率下降会影响鸟类个体间识别、配偶关系、领域防卫、种群密度、群落结构等.本文综述了城市噪音、自然噪音等环境噪声对鸟类鸣声的影响以及鸟类的适应对策,提出在城市化进程中要关注噪音对鸟类的影响,并展望了本领域今后可能的研究热点.

  12. Development of a low cost method to estimate the seismic signature of a geothermal field from ambient seismic noise analysis, Authors: Tibuleac, I. M., J. Iovenitti, S. Pullammanapallil, D. von Seggern, F.H. Ibser, D. Shaw and H. McLahlan

    Science.gov (United States)

    Tibuleac, I. M.; Iovenitti, J. L.; Pullammanappallil, S. K.; von Seggern, D. H.; Ibser, H.; Shaw, D.; McLachlan, H.

    2015-12-01

    A new, cost effective and non-invasive exploration method using ambient seismic noise has been tested at Soda Lake, NV, with promising results. Seismic interferometry was used to extract Green's Functions (P and surface waves) from 21 days of continuous ambient seismic noise. With the advantage of S-velocity models estimated from surface waves, an ambient noise seismic reflection survey along a line (named Line 2), although with lower resolution, reproduced the results of the active survey, when the ambient seismic noise was not contaminated by strong cultural noise. Ambient noise resolution was less at depth (below 1000m) compared to the active survey. Useful information could be recovered from ambient seismic noise, including dipping features and fault locations. Processing method tests were developed, with potential to improve the virtual reflection survey results. Through innovative signal processing techniques, periods not typically analyzed with high frequency sensors were used in this study to obtain seismic velocity model information to a depth of 1.4km. New seismic parameters such as Green's Function reflection component lateral variations, waveform entropy, stochastic parameters (Correlation Length and Hurst number) and spectral frequency content extracted from active and passive surveys showed potential to indicate geothermal favorability through their correlation with high temperature anomalies, and showed potential as fault indicators, thus reducing the uncertainty in fault identification. Geothermal favorability maps along ambient seismic Line 2 were generated considering temperature, lithology and the seismic parameters investigated in this study and compared to the active Line 2 results. Pseudo-favorability maps were also generated using only the seismic parameters analyzed in this study.

  13. Spectral ratios of ambient noise based on the diffuse field theory: Improved inversion of H/V in layered media using analytical properties of Green functions

    Science.gov (United States)

    Sanchez-Sesma, F. J.; Perton, M.; Piña, J.; Luzón, F.; Garcia-Jerez, A.; Rodriguez-Castellanos, A.

    2013-12-01

    It is well know the popularity of H/V spectral ratio to extract the dominant frequency of soil sites for microzonation studies (Nakamura, 1989). It is relatively easy to make measurements as only one station is needed. Despite its success, this approach had not solid theoretical basis until a proposal to link ambient noise vibrations with diffuse field theory was made (Sánchez-Sesma et al, 2011a). Based on this theory the average spectral density of a given motion of a point, also called directional energy density (Perton et al, 2009), is proportional to the imaginary part of Green function precisely at the observation point. The proportionality implies that vector components are all multiplied by the current spectral level of the diffuse illumination. Appropriate normalization is crucial to make the experimental spectral ratios closer to the theoretical counterpart. According to this theory the square of H/V is twice the ratio of ImG11 and ImG33, where ImG11 and ImG33 are the imaginary part of Green functions at the load point for horizontal and vertical components, respectively. From ImG11 it could be possible through Fourier analysis to extract pseudo reflections and thus constrain the inversion of soil profile. We propose to assess ImG11 removing the influence of illumination spectrum using the H/V spectral ratio and an estimate of ImG33 (obtained from a priori model) by means of ImG11=0.5(H/V)2*ImG33. It has been found that ImG33 is less sensitive to details of stratigraphy. In fact, the most relevant property is the Poisson ratio of the uppermost layer which controls the slope in high frequency (Sánchez-Sesma et al, 2011b). Pseudo-reflection seismograms are thus obtained from Fourier transform, back to time domain, of i{ImG11-ImG11HSS}, where ImG11HSS is the imaginary part of Green functions at the load point for horizontal load at the surface of a half-space with the properties of the uppermost layer. With the obtained model ImG33 can be updated and the

  14. 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.

  15. Development and research of shallow water ambient noise database%潜水环境噪声数据库设计与开发

    Institute of Scientific and Technical Information of China (English)

    方鹏

    2015-01-01

    随着人类水下活动和实验行为的增多,越来越多的应用需要借助水声探测技术和水声通信技术,而在潜水环境中,环境噪声是以上技术的重要制约因素。因而,了解相应海域的环境噪声特性并建立环境噪声数据库,将有助于该海域的航运、测绘、通信等水声技术的应用与发展。本文针对以上需求,提出一种噪声建模方法,并根据该方法设计和研究相应的潜水环境噪声数据库。实验证明本文提出的方法具有一定的可行性。%Along with the increase in human activities and underwater experimental behavior, more and more applications need to use acoustic detection technology and underwater acoustic communication technology, and in the diving environment, environmental noise is one of the important restriction factor to the technology above. Therefore, to understand the corresponding environmental noise characteristics of waters and establishing database of environmental noise, would help surveying and mapping, navigation, communication etc. with application and development of underwater acoustic technology. In view of the above requirements, this paper puts forward a kind of noise modeling method, and research the method of design and research the corresponding diving database of environmental noise. Finally this paper gives the experimental verification, and demonstrates that the proposed method has certain feasibility.

  16. Ambient seismic noise tomography reveals a hidden caldera and its relation to the Tarutung pull-apart basin at the Sumatran Fault Zone, Indonesia

    Science.gov (United States)

    Ryberg, Trond; Muksin, Umar; Bauer, Klaus

    2016-07-01

    We analyzed the noise recordings of a short-period seismic network to derive a shallow crustal S-wave velocity model at the Sumatra Fault in Northern Sumatra, Indonesia. By correlating the noise of 40 seismic stations' recording for 9 months, we could recover Rayleigh waves from vertical component recordings with sufficient signal-to-noise ratio. Group velocities of the Rayleigh waves could be determined in the period range from 0.71 to 4.4 s. These group velocities were used to invert for 2D group velocity maps at specific periods. Finally, the derived group velocity maps were inverted for a 3D S-wave velocity model. This model shows a region of a strong velocity decrease off the Great Sumatran Fault Zone, at the northeastern margin of the young Tarutung pull-apart basin. This observed low velocity block coincides with a caldera-like morphological feature which is interpreted as the surface expression of a hidden volcanic caldera. Considering the surface manifestations of geothermal activity around this anomaly, we conclude that the caldera is still acting as a heat source. On the other hand, the weak morphological expression at the surface indicates a certain age of the caldera which might be older than the Tarutung pull-apart basin. The findings provide important constraints on general concepts for the formation of pull-apart basins along the Sumatran fault and their relation to volcanism.

  17. The challenge of localizing vehicle backup alarms: Effects of passive and electronic hearing protectors, ambient noise level, and backup alarm spectral content

    Directory of Open Access Journals (Sweden)

    Khaled A Alali

    2011-01-01

    Full Text Available A human factors experiment employed a hemi-anechoic sound field in which listeners were required to localize a vehicular backup alarm warning signal (both a standard and a frequency-augmented alarm in 360-degrees azimuth in pink noise of 60 dBA and 90 dBA. Measures of localization performance included: (1 percentage correct localization, (2 percentage of right--left localization errors, (3 percentage of front-rear localization errors, and (4 localization absolute deviation in degrees from the alarm′s actual location. In summary, the data demonstrated that, with some exceptions, normal hearing listeners′ ability to localize the backup alarm in 360-degrees azimuth did not improve when wearing augmented hearing protectors (including dichotic sound transmission earmuffs, flat attenuation earplugs, and level-dependent earplugs as compared to when wearing conventional passive earmuffs or earplugs of the foam or flanged types. Exceptions were that in the 90 dBA pink noise, the flat attenuation earplug yielded significantly better accuracy than the polyurethane foam earplug and both the dichotic and the custom-made diotic electronic sound transmission earmuffs. However, the flat attenuation earplug showed no benefit over the standard pre-molded earplug, the arc earplug, and the passive earmuff. Confusions of front-rear alarm directions were most significant in the 90 dBA noise condition, wherein two types of triple-flanged earplugs exhibited significantly fewer front-rear confusions than either of the electronic muffs. On all measures, the diotic sound transmission earmuff resulted in the poorest localization of any of the protectors due to the fact that its single-microphone design did not enable interaural cues to be heard. Localization was consistently more degraded in the 90 dBA pink noise as compared with the relatively quiet condition of the 60 dBA pink noise. A frequency-augmented backup alarm, which incorporated 400 Hz and 4000 Hz components

  18. Ambiente urbano e percepção da poluição sonora Urban environment and perception to noise pollution

    OpenAIRE

    Adriana Bender Moreira de Lacerda; Cristiana Magni; Thais Catalani Morata; Jair Mendes Marques; Paulo Henrique Trombetta Zannin

    2005-01-01

    A presente pesquisa avaliou a percepção da população de uma grande cidade em relação à poluição sonora (ruído urbano). Buscou-se identificar quais fontes sonoras são percebidas com maior freqüência pela população e quais reações psico-sociais relacionadas ao ruído urbano são identificados por ela. Foi utilizado um questionário composto de questões fechadas, abrangendo aspectos demográficos e aspectos psico-sociais referentes ao ruído ambiental. Oitocentos e noventa e dois (892) indivíduos par...

  19. 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...

  20. Velocity variations associated with the large 2010 eruption of Merapi volcano, Java, retrieved from seismic multiplets and ambient noise cross-correlation

    Science.gov (United States)

    Budi-Santoso, Agus; Lesage, Philippe

    2016-07-01

    We present a study of the seismic velocity variations that occurred in the structure before the large 2010 eruption of Merapi volcano. For the first time to our knowledge, the technique of coda wave interferometry is applied to both families of similar events (multiplets) and to correlation functions of seismic noise. About half of the seismic events recorded at the summit stations belong to one of the ten multiplets identified, including 120 similar events that occurred in the last 20 hr preceding the eruption onset. Daily noise cross-correlation functions (NCF) were calculated for the six pairs of short-period stations available. Using the stretching method, we estimate time-series of apparent velocity variation (AVV) for each multiplet and each pair of stations. No significant velocity change is detected until September 2010. From 10 October to the beginning of the eruption on 26 October, a complex pattern of AVV is observed with amplitude of up to ±1.5 per cent. Velocity decrease is first observed from families of deep events and then from shallow earthquakes. In the same period, AVV with different signs and chronologies are estimated from NCF calculated for various station pairs. The location in the horizontal plane of the velocity perturbations related with the AVV obtained from NCF is estimated by using an approach based on the radiative transfer approximation. Although their spatial resolution is limited, the resulting maps display velocity decrease in the upper part of the edifice in the period 12-25 October. After the eruption onset, the pattern of velocity perturbations is significantly modified with respect to the previous one. We interpret these velocity variations in the framework of a scenario of magmatic intrusion that integrates most observations. The perturbation of the stress field associated with the magma migration can induce both decrease and increase of the seismic velocity of rocks. Thus the detected AVVs can be considered as precursors of

  1. Noise suppression by noise

    OpenAIRE

    Vilar, J. M. G.; 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.

  2. 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...

  3. Application of the energy reassignment method to measure accurate Rayleigh and Love wave group velocities from ambient seismic noise cross-correlations

    Science.gov (United States)

    Witek, M.; Kang, T. S.; van der Lee, S.

    2015-12-01

    We have collected three-component data from 122 Korean accelerometer stations for the month of December in 2014. We apply similar techniques described by Zha et al. (2013) to retrieve accurate station orientation angles, in order to rotate the horizontal component data into the radial and transverse frame of reference, and for subsequent measurement of Love wave group velocity dispersion. We simultaneously normalize all three components of a daily noise record via the frequency-time normalization (FTN) method. Each component is divided by the average signal envelope in an effort to retain relative amplitude information between all three components. Station orientations are found by a grid search for the orientation azimuth which maximizes the coherency between the radial-vertical cross-correlation and the Hilbert transformed vertical-vertical cross-correlation. After measuring orientation angles, we cross-correlate and rotate the data. Typically, the group velocity dispersion curves are measured using the frequency time analysis technique (FTAN), effectively producing spectrograms with significant uncertainty in the time-frequency plane. The spectrogram approach retains only the amplitude information of the short-time Fourier transform (STFT). However, Kodera et al (1976) show that by taking into account the phase information, the concepts of instantaneous frequency and group-time delay can be used to compute the first moment of the signal power in the frequency and time domains. During energy reassignment, the signal power calculated using the STFT at a point (t0,f0t_0, f_0) is reassigned to the location of the first moment (t^g,f^ihat{t}_g,hat{f}_i), where t^ghat{t}_g is the group-time delay and f^ihat{f}_i is the instantaneous frequency. We apply the method of energy reassignment to produce precise Rayleigh and Love wave group velocity measurements in the frequency range 0.1 - 1.0 Hz. Tests on synthetic data show more accurate retrieval of group velocities at

  4. 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...

  5. 3-D Shear Wave Velocity Model of Mexico and South US: Bridging Seismic Networks with Ambient Noise Cross-Correlations (C1) and Correlation of Coda of Correlations (C3).

    Science.gov (United States)

    Spica, Zack; Perton, Mathieu; Calò, Marco; Legrand, Denis; Córdoba Montiel, Francisco; Iglesias, Arturo

    2016-07-01

    This work presents an innovative strategy to enhance the resolution of surface wave tomography obtained from ambient noise cross-correlation (C1) by bridging asynchronous seismic networks through the correlation of coda of correlations (C3). Rayleigh wave group dispersion curves show consistent results between synchronous and asynchronous stations. Rayleigh wave group travel times are inverted to construct velocity-period maps with unprecedented resolution for a region covering Mexico and the southern United States. The resulting period maps are then used to regionalize dispersion curves in order to obtain local 1-D shear velocity models (VS) of the crust and uppermost mantle in every cell of a grid of 0.4°. The 1-D structures are obtained by iteratively adding layers until reaching a given misfit, and a global tomography model is considered as an input for depths below 150 km. Finally, a high-resolution 3-D VS model is obtained from these inversions. The major structures observed in the 3-D model are in agreement with the tectonic-geodynamic features and with previous regional and local studies. It also offers new insights to understand the present and past tectonic evolution of the region.

  6. 3-D shear wave velocity model of Mexico and South US: bridging seismic networks with ambient noise cross-correlations (C1) and correlation of coda of correlations (C3)

    Science.gov (United States)

    Spica, Zack; Perton, Mathieu; Calò, Marco; Legrand, Denis; Córdoba-Montiel, Francisco; Iglesias, Arturo

    2016-09-01

    This work presents an innovative strategy to enhance the resolution of surface wave tomography obtained from ambient noise cross-correlation (C1) by bridging asynchronous seismic networks through the correlation of coda of correlations (C3). Rayleigh wave group dispersion curves show consistent results between synchronous and asynchronous stations. Rayleigh wave group traveltimes are inverted to construct velocity-period maps with unprecedented resolution for a region covering Mexico and the southern United States. The resulting period maps are then used to regionalize dispersion curves in order to obtain local 1-D shear velocity models (VS) of the crust and uppermost mantle in every cell of a grid of 0.4°. The 1-D structures are obtained by iteratively adding layers until reaching a given misfit, and a global tomography model is considered as an input for depths below 150 km. Finally, a high-resolution 3-D VS model is obtained from these inversions. The major structures observed in the 3-D model are in agreement with the tectonic-geodynamic features and with previous regional and local studies. It also offers new insights to understand the present and past tectonic evolution of the region.

  7. Smooth bumps in H/V curves over a broad area from single-station ambient noise recordings are meaningful and reveal the importance of Q in array processing: The Boumerdes (Algeria) case

    Science.gov (United States)

    Guillier, B.; Chatelain, J.-L.; Hellel, M.; Machane, D.; Mezouer, N.; Ben Salem, R.; Oubaiche, E. H.

    2005-12-01

    Single-station H/V curves from ambient noise recordings in Boumerdes (Algeria) show smooth bumps around 1 and 3 Hz. A complementary microtremor study, based on two 34 and 134-meter aperture arrays, evidences that these bumps are indeed real peaks produced by two strong VS contrasts at 37 and 118 meters depth, strongly smoothed by very high S-wave attenuation in the two sedimentary layers. These two H/V bumps, observed over a broad area, are meaningful and reveal the importance of Q in S-wave velocity modeling from microtremor array data processing. It also appears that Tertiary rocks should be, at least in some cases, taken into account, together with the Quaternary sediments, to explain single-station H/V frequency peaks, and therefore that considering only the first 30 m of soil for VS amplification evaluation, as usually recommended, sometimes leads to flaky results by artificially eliminating non-explained low-frequency peaks from the analysis.

  8. Synchronized pulsed LED algorithm for ambient infrared noise minimization in FTIR-based multi-touch systems%基于同步脉冲光源的抗环境红外FTIR多点触摸算法

    Institute of Scientific and Technical Information of China (English)

    李江晨; 徐小维; 韩君佩; 胡昱; 邹雪城

    2013-01-01

      多点触摸技术已应用在生活的诸多方面,带来了人机交互上的巨大便利。在多种新型的基于视觉的多点触摸技术中FTIR技术是极具潜力的优势技术,但是该技术会受环境红外噪声干扰,不能有效识别日光环境下的手指触点信号。针对环境红外噪声干扰的问题,提出了一种基于同步脉冲光源的相邻帧差算法(SPLA)使得FTIR技术具有良好的抗环境红外噪声的特点,可在日光环境中有效识别手指触点。同时还构建了嵌入同步脉冲光源的多点触摸硬件平台,实现了SPLA算法,并进行了大量的触摸实验。实验结果表明,相比于传统的背景差算法,SPLA算法的触点对比度提高了将近3.5倍,可以准确地识别出触摸点。鉴于硬件实现的通用性,SPLA算法还可应用到其他多点触摸平台,具有较强的可移植性。%The multi-touch technology has been widely used in various aspects of the every-day life, and has brought tremendous convenience during the process of the human-computer interaction. Among many new vision-based implementation methods for the multi-touch function, the frustrated total internal reflection (FTIR) method is one of the most promising one with unique advantages. However, the FTIR-based multi-touch implementation is sensitive to the ambient infrared noise and it currently can only be used in the dark environment. In this paper, a synchronized pulsed LED algorithm was proposed, namely SPLA, which could effectively improve the sensitivity of the FTIR-based multi-touch implementation in the normal ambient lighting environment. Based on the SPLA, a FTIR-based multi-touch platform was implemented . The experimental results show that the proposed SPLA increases the contrast of the blobs (touch points) by 3.5 times compared with the conventional methods. Because of similar hardware structure, the proposed SPLA can be also extended to minimize the ambient noise for

  9. THE ACOUSTIC CONTAMINATION OF SCHOOL ENVIRONMENT DUE TO URBAN NOISES IN THE FEDERAL DISTRICT, BRASIL = A CONTAMINAÇÃO ACÚSTICA DE AMBIENTES ESCOLARES DEVIDO AOS RUÍDOS URBANOS NO DISTRITO FEDERAL, BRASIL

    Directory of Open Access Journals (Sweden)

    Alexandre Eniz

    2006-01-01

    Full Text Available Urban noises are more and more presents in our daily life, invading residences, work places, leisure locations, hospitals and schools, becoming a potential harm to social interaction, communication, behavior, school performance, health etc. The main objective of this work was to analyze and quantify the environmental noise in ten schools of the basic education in District Federal, Brazil. The adopted parameter was the equivalent sound pressure level Leq (A, which was evaluated according to the sound level measures following the standard established by Brazilian Association of echnical Regulations (ABNT. The background noise was measured during holidays and during regular class periods. The study detected that half of the schools researched are being “contaminated” with noise from aircraft, road traffic, trucks, advertising vehicles, motorcycles, buses among other sources, with limits outside the recommended by law. In 90% of the evaluated schools, the noise levels observed during the activities are above of the maximum values recommended for the acoustic comfort of a school. These are buildings ill-located in the city and therefore “exposed” to levels that are above of recommended by the norms. The results show a critical situation indicating the urgent need of actions with the objective of mitigating this severe type of pollution. = Os ruídos urbanos estão cada vez mais presentes em nosso cotidiano, invadindo residências, locais de trabalho, de lazer, hospitais e escolas, podendo prejudicar as relações sociais, a comunicação, o comportamento, o rendimento escolar, a saúde etc. O objetivo principal deste trabalho foi analisar e quantificar o ruído ambiental em dez escolas do Ensino Fundamental e Médio no Distrito Federal. O parâmetro adotado foi o nível de pressão sonora equivalente Leq (A, avaliado por medidores de pressão sonora, segundo as normas estabelecidas pela Associação Brasileira de NormasTécnicas (ABNT. O ru

  10. Ambient Gestures

    OpenAIRE

    Karam, Maria; Hare, Jonathon; Lewis, Paul; schraefel, m.c.

    2006-01-01

    We present Ambient Gestures, a novel gesture-based system designed to support ubiquitous ‘in the environment’ interactions with everyday computing technology. Hand gestures and audio feedback allow users to control computer applications without reliance on a graphical user interface, and without having to switch from the context of a non-computer task to the context of the computer. The Ambient Gestures system is composed of a vision recognition software application, a set of gestures to be p...

  11. Noise blind test

    OpenAIRE

    H. Cadet

    2006-01-01

    In the aim of characterizing site condition for seismic risk, the microtremor or ambient noise studies have been developed. The main objective of this blind test is to check of the reliability of results, to observe the user subjectivity (array choice, parameters that are user depend) in the noise recordings analyze. Noise records were analysed on single-station with H/V method and with several sensors for array method to determine the dispersion characteristics of the surface-wave part of th...

  12. Ambient Noise Tomography of the Central India

    Directory of Open Access Journals (Sweden)

    Abhay P. Singh,

    2011-05-01

    Full Text Available In the recent years, earthquakes have been used in understanding the Earth. The travel times of the body waves; P and S waves, the dispersion of the group and phase velocities of the surface waves and the information derived from the normal modes of the Earth gave information to extract the structure of the Earth’s interior.

  13. Ambient noise levels in the chemotherapy clinic

    OpenAIRE

    Dana K Gladd; Saunders, Gabrielle H.

    2011-01-01

    Many of the drugs used for chemotherapy treatments are known to be ototoxic, and can result in permanent hearing threshold shifts. The degree of ototoxic damage can be influenced by many factors including dosage, duration of exposure, genetics, and coadministration with other ototoxic agents. Cisplatin is known for its ototoxic effects on hearing thresholds, particularly in the high frequencies. Recent studies have indicated a synergistic relationship between Cisplatin administration and mode...

  14. Noise Pollution

    Science.gov (United States)

    ... Overview » Title IV - Noise Pollution Title IV - Noise Pollution The 1990 Clean Air Act Amendments added a ... abatement 7642 Authorization of appropriations What is Noise Pollution? The traditional definition of noise is “unwanted or ...

  15. 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)

  16. 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

  17. Extracting information from noise

    OpenAIRE

    Baptie, Brian

    2010-01-01

    Seismic waves created by sources such as wind, the ocean and human activity propagate inside the Earth all the time. Such waves are often regarded as ‘noise’ by seismologists, however, they travel through the Earth in exactly the same way as those waves from earthquakes. Recent advances in theory have shown that ambient noise recorded at two seismic stations can be combined to provide information about the properties of the Earth between the two stations. This is known as seism...

  18. ENVIRONMENTAL LAW APPLICABLE TO URBAN NOISE POLLUTION: A STUDY ON THE STANDARDS AND DISCIPLINERY DIRECTIVES = LEGISLAÇÃO AMBIENTAL APLICÁVEL À POLUIÇÃO SONORA URBANA: UM ESTUDO DAS NORMAS E DIRETRIZES DISCIPLINARES

    OpenAIRE

    Nivar Gobbi; Patricia Satie Mochizuki; Adriano Bressane; Marcelo Diniz Carvalho

    2008-01-01

    A factor contributing to increasing urban degradation is noise pollution, discussed on this study in relation to the applicable Federal Brazilian legislation with the aim of contributing to inform the actions of decision makers who seek to recover quality of life that has been compromised by noise and protect their cities from this problem. The result is a compilation of solutions for the principal causes of urban noise conflicts. = Diante da crescente degradação dos cenários urbanos vem se d...

  19. Snowmobile noise

    OpenAIRE

    Liikonen, Larri; Alanko, Mikko; Jokinen, Sirpa; Niskanen, Ilkka; Virrankoski, Lauri

    2007-01-01

    Planning snowmobiling routes and considering the possible need for off-road traffic restrictions requires that the noise impact of snowmobile traffic is known. The objective of this report was to take off-road readings in order to determine snowmobile noise emissions and the spread of noise from snowmobile routes into the environment. Based on the readings taken, it can be said that the noise zones created by snowmobile traffic are quite narrow at current traffic levels. Noise pollution ca...

  20. Industrial Noise

    OpenAIRE

    Mehran zolfaghari

    1996-01-01

    Various risk factors in industrial environments can affect hearing status and healthy in today’s modern society. Noise control and hearing conservation program is very crucial in preventing workers exposed to high levels of noise in the work places. In the current article we are going to discuss issues such as industrial noise control, noise characteristics and standards and techniques for noise control. Then the methods for individual hearing conservation and medical care will be described i...

  1. Adaptive noise

    OpenAIRE

    Viney, Mark; Reece, Sarah E.

    2013-01-01

    In biology, noise implies error and disorder and is therefore something which organisms may seek to minimize and mitigate against. We argue that such noise can be adaptive. Recent studies have shown that gene expression can be noisy, noise can be genetically controlled, genes and gene networks vary in how noisy they are and noise generates phenotypic differences among genetically identical cells. Such phenotypic differences can have fitness benefits, suggesting that evolution can shape noise ...

  2. THE ACOUSTIC CONTAMINATION OF SCHOOL ENVIRONMENT DUE TO URBAN NOISES IN THE FEDERAL DISTRICT, BRASIL = A CONTAMINAÇÃO ACÚSTICA DE AMBIENTES ESCOLARES DEVIDO AOS RUÍDOS URBANOS NO DISTRITO FEDERAL, BRASIL

    OpenAIRE

    Alexandre Eniz; Sérgio Luiz Garavelli

    2006-01-01

    Urban noises are more and more presents in our daily life, invading residences, work places, leisure locations, hospitals and schools, becoming a potential harm to social interaction, communication, behavior, school performance, health etc. The main objective of this work was to analyze and quantify the environmental noise in ten schools of the basic education in District Federal, Brazil. The adopted parameter was the equivalent sound pressure level Leq (A), which was evaluated according to t...

  3. CNOSSOS-EU: Development of a common environmental noise assessment method in the European Union; CNOSSOS-EU: desarrollo de un metodo comun de evaluacion del ruido ambiental en la Union Europea

    Energy Technology Data Exchange (ETDEWEB)

    Aspuru Soloaga, I.; Segues Echazarreta Segues, F.

    2011-07-01

    This article presents the main aspects of the work undertaken in the development of the common european method of environmental noise assessment CNOSSOS-EU. It summarizes the design, structure and content, and the methodological basis on which it is based. Taking into account the experience gained in the first round of strategic noise mapping, some conclusions are settled about its applications for the third round, and tits implications for the Spanish case. (Author) 9 refs.

  4. Unjust noise

    OpenAIRE

    Paul Voice

    2009-01-01

    In this paper I argue that noise is a significant source of social harm and thoseharmed by noise often suffer not merely a misfortune but an injustice. I arguethat noise is a problem of justice in two ways; firstly, noise is a burden of socialcooperation and so the question of the distribution of this burden arises. And,secondly, some noises, although burdensome, are nevertheless just becausethey arise from practices that are ‘reasonable’. I offer a number of distinctions,between necessary an...

  5. ENVIRONMENTAL LAW APPLICABLE TO URBAN NOISE POLLUTION: A STUDY ON THE STANDARDS AND DISCIPLINERY DIRECTIVES = LEGISLAÇÃO AMBIENTAL APLICÁVEL À POLUIÇÃO SONORA URBANA: UM ESTUDO DAS NORMAS E DIRETRIZES DISCIPLINARES

    Directory of Open Access Journals (Sweden)

    Nivar Gobbi

    2008-01-01

    Full Text Available A factor contributing to increasing urban degradation is noise pollution, discussed on this study in relation to the applicable Federal Brazilian legislation with the aim of contributing to inform the actions of decision makers who seek to recover quality of life that has been compromised by noise and protect their cities from this problem. The result is a compilation of solutions for the principal causes of urban noise conflicts. = Diante da crescente degradação dos cenários urbanos vem se destacando a Poluição Sonora, discutida nesse estudo no contexto da Legislação Federal aplicável, visando contribuir com a atuação de gestores que buscam restabelecer a qualidade de vida comprometida pelo ruído e, sobretudo, objetivam prevenir suas cidades contra esse problema. Como resultado, foi reunido um amplo e abrangente conjunto de soluções legislativas contemplando as principais causas de conflitos sonoros urbanos.

  6. Feminizing noise

    OpenAIRE

    Thompson, Marie

    2014-01-01

    Marie will explore the relationship between constructions of femininity and noise, which is understood here as an affective transformative force, rather than simply as unwanted sound. She will suggest that ‘feminine’ noises are often deemed negative; not because of what they mean, but as a result of the transformations they threaten to induce. Marie will raise questions around essentialism – does talking of a feminine or feminized noise require us to adopt an essentialist position, or can an ...

  7. Noise Traders

    OpenAIRE

    James Dow; Gary Gorton

    2006-01-01

    Noise traders are agents whose theoretical existence has been hypothesized as a way of solving certain fundamental problems in Financial Economics. We briefly review the literature on noise traders. The is an entry for The New Palgrave: A Dictionary of Economics, 2nd Edition (Palgrave Macmillan: New York), edited by Steven N. Durlauf and Lawrence E. Blume, forthcoming in 2008.

  8. Aircraft Noise

    Science.gov (United States)

    Michel, Ulf; Dobrzynski, Werner; Splettstoesser, Wolf; Delfs, Jan; Isermann, Ullrich; Obermeier, Frank

    Aircraft industry is exposed to increasing public pressure aiming at a continuing reduction of aircraft noise levels. This is necessary to both compensate for the detrimental effect on noise of the expected increase in air traffic and improve the quality of living in residential areas around airports.

  9. Uso de ardósia na construção de celas de maternidade para suínos: II - ambiente térmico e avaliação dos ruídos Use of slate to built swine nursery cells: II - thermal environment and noise evaluation

    Directory of Open Access Journals (Sweden)

    Jaqueline de O. Castro

    2013-02-01

    Full Text Available Este trabalho teve o objetivo de avaliar o ambiente térmico e o ruído em celas de maternidade para suínos com divisórias de alvenaria ou com rochas de ardósia. Para as medidas das variáveis de conforto térmico e de ruídos, utilizaram-se de termômetros e decibelímetro. No interior das celas e para a análise estatística, foram usados doze matrizes e cento e trinta e nove leitões, distribuídos em delineamento em blocos casualizados, em esquema de parcelas subdivididas. Os resultados mostraram que, no período da manhã, em ambos os tratamentos, as condições de conforto térmico foram mais adequadas para as matrizes, enquanto no período da tarde, mais adequadas para os leitões; com relação ao ruído, este foi menor nas celas de alvenaria. De forma geral, o ambiente no interior das celas construídas em ardósia apresentou umidade relativa mais baixa, e ITGU e temperatura mais elevada que as celas construídas em alvenaria. O nível de ruídos permaneceu dentro dos limites considerados ideais para suínos em ambos os tratamentos.The aim of the present study was to evaluate the thermal environment and noise levels in swine farrowing cells built with masonry or slate. Thermometers and sound level meter equipment were used to measure the thermal comfort variables. Inside the cells and for the statistical analysis, twelve sows and one hundred thirty-nine piglets were used, distributed in a randomized blocks design in a split-plot arrangement. The results showed that in the morning, in both treatments, the thermal comfort conditions were more suitable for sows, while in the afternoon it was more suitable for piglets. The noise was lower in the masonry cells. Overall, the environment inside in the cells built with slate presented lower relative humidity and, higher BGHI and temperature than those built with masonry. The noise level remained within the thresholds considered as ideal for swine in both treatments.

  10. Intermittent Noise Induces Physiological Stress in a Coastal Marine Fish.

    Directory of Open Access Journals (Sweden)

    Tye A Nichols

    Full Text Available Anthropogenic noise in the ocean has increased substantially in recent decades, and motorized vessels produce what is likely the most common form of underwater noise pollution. Noise has the potential to induce physiological stress in marine fishes, which may have negative ecological consequences. In this study, physiological effects of increased noise (playback of boat noise recorded in the field on a coastal marine fish (the giant kelpfish, Heterostichus rostratus were investigated by measuring the stress responses (cortisol concentration of fish to increased noise of various temporal dynamics and noise levels. Giant kelpfish exhibited acute stress responses when exposed to intermittent noise, but not to continuous noise or control conditions (playback of recorded natural ambient sound. These results suggest that variability in the acoustic environment may be more important than the period of noise exposure for inducing stress in a marine fish, and provide information regarding noise levels at which physiological responses occur.

  11. Intermittent Noise Induces Physiological Stress in a Coastal Marine Fish.

    Science.gov (United States)

    Nichols, Tye A; Anderson, Todd W; Širović, Ana

    2015-01-01

    Anthropogenic noise in the ocean has increased substantially in recent decades, and motorized vessels produce what is likely the most common form of underwater noise pollution. Noise has the potential to induce physiological stress in marine fishes, which may have negative ecological consequences. In this study, physiological effects of increased noise (playback of boat noise recorded in the field) on a coastal marine fish (the giant kelpfish, Heterostichus rostratus) were investigated by measuring the stress responses (cortisol concentration) of fish to increased noise of various temporal dynamics and noise levels. Giant kelpfish exhibited acute stress responses when exposed to intermittent noise, but not to continuous noise or control conditions (playback of recorded natural ambient sound). These results suggest that variability in the acoustic environment may be more important than the period of noise exposure for inducing stress in a marine fish, and provide information regarding noise levels at which physiological responses occur. PMID:26402068

  12. Psicologia do Ambiente

    OpenAIRE

    Antunes, Dalila; Bernardo, Fátima; Palma-Oliveira, José-Manuel

    2011-01-01

    Na aplicação da Psicologia à área do AMBIENTE importa em primeiro lugar definir o que se entende, neste contexto, por ambiente. O conceito é entendido como toda a envolvente que rodeia o ser humano. Referimo-nos pois ao espaço físico e aos estímulos que nele existem (som, ar, paisagem…), dirigindo-se a Psicologia do Ambiente ao estudo e intervenção sobre a forma como o ambiente influencia o indivíduo ou grupos, e sobre o modo como o comportamento dos indivíduos e grupos influenciam o ambiente...

  13. 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...

  14. Chasing Noise

    OpenAIRE

    Mendel, Brock; Shleifer, Andrei

    2012-01-01

    We present a simple model in which rational but uninformed traders occasionally chase noise as if it were information, thereby amplifying sentiment shocks and moving prices away from fundamental values. We fill a theoretical gap in the literature by showing conditions under which noise traders can have an impact on market equilibrium disproportionate to their size in the market. The model offers a partial explanation for the surprisingly low market price of financial risk in the Spring of 2007.

  15. Crackling Noise

    OpenAIRE

    Sethna, James P.; Dahmen, Karin A.; Christopher R Myers

    2001-01-01

    Crackling noise arises when a system responds to changing external conditions through discrete, impulsive events spanning a broad range of sizes. A wide variety of physical systems exhibiting crackling noise have been studied, from earthquakes on faults to paper crumpling. Because these systems exhibit regular behavior over many decades of sizes, their behavior is likely independent of microscopic and macroscopic details, and progress can be made by the use of very simple models. The fact tha...

  16. Noise Bubbles

    OpenAIRE

    Mario Forni; Luca Gambetti; Marco Lippi; Luca Sala

    2014-01-01

    We introduce noisy information into a standard present value stock price model. Agents receive a noisy signal about the structural shock driving future dividend variations. The resulting equilibrium stock price includes a transitory component — the "noise bubble" — which can be responsible for boom and bust episodes unrelated to economic fundamentals. We propose a non-standard VAR procedure to estimate the structural shock and the "noise" shock, their impulse response functions and the bubble...

  17. Nível de ruído no ambiente de trabalho do professor de educação física em aulas de ciclismo indoor Nivel de ruido en el ambiente de trabajo del profesor de educación física en aulas de ciclismo indoor Level of noise at the workplace environment among physical education teachers in indoor bike classes

    Directory of Open Access Journals (Sweden)

    Alexandre Palma

    2009-04-01

    Full Text Available OBJETIVO: Analisar o nível de ruído no ambiente de trabalho do professor de educação física durante as aulas de ciclismo indoor e sua associação com alguns aspectos da saúde. MÉTODOS: Estudo transversal conduzido com 15 professores de educação física de diferentes academias de ginástica, na cidade do Rio de Janeiro (RJ, em 2007. As características do processo e da organização do trabalho e as queixas de saúde relatadas pelos professores foram coletadas por meio de questionário padronizado. Para verificação dos transtornos psiquiátricos menores foi usado o SRQ-20 (Self-Report Questionnaire. As medidas de pressão sonora foram realizadas em um aparelho portátil. O nível de pressão foi medido em dB(A no nível equivalente de energia em diferentes pontos da sala e momentos da aula. As análises estatísticas utilizadas foram a ANOVA, o qui-quadrado e a correlação de Pearson. RESULTADOS: Os níveis de pressão sonora variaram entre 74,4 dB(A e 101,6 dB(A. Os valores médios encontrados durante as aulas foram: a aquecimento (média= 88,45 dB(A; b parte principal (média= 95,86 dB(A; e, fechamento (média= 85,12 dB(A. O ruído de fundo apresentou o valor médio de 66,89 dB(A. Houve diferenças significativas (pOBJETIVO: Analizar el nivel de ruido en el ambiente de trabajo del profesor de educación física durante las aulas de ciclismo indoor y su asociación con algunos aspectos de la salud. MÉTODOS: Estudio transversal conducido con 15 profesores de educación física de diferentes academias de ejercicio, en la ciudad de Río de Janeiro (Sureste de Brasil, en 2007. Las características del proceso y de la organización de trabajo y los reclamos de salud relatados por los profesores fueron colectados por medio de cuestionario estandarizado. Para verificar los trastornos psiquiátricos menores fue usado el SRQ-20 (Self Report Questionnaire. Las medidas de presión sonora fueron realizadas en un aparato portátil. El nivel de

  18. 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.

  19. Road traffic noise and incident myocardial infarction: a prospective cohort study

    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....

  20. Noise-free magnetoencephalography recordings of brain function

    Energy Technology Data Exchange (ETDEWEB)

    Volegov, P; Matlachov, A; Mosher, J; Espy, M A; Kraus, R H Jr. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2004-05-21

    Perhaps the greatest impediment to acquiring high-quality magnetoencephalography (MEG) recordings is the ubiquitous ambient magnetic field noise. We have designed and built a whole-head MEG system using a helmet-like superconducting imaging surface (SIS) surrounding the array of superconducting quantum interference device (SQUID) magnetometers used to measure the MEG signal. We previously demonstrated that the SIS passively shields the SQUID array from ambient magnetic field noise, independent of frequency, by 25-60 dB depending on sensor location. SQUID 'reference sensors' located on the outside of the SIS helmet measure ambient magnetic fields in very close proximity to the MEG magnetometers while being nearly perfectly shielded from all sources in the brain. The fact that the reference sensors measure no brain signal yet are located in close proximity to the MEG sensors enables very accurate estimation and subtraction of the ambient field noise contribution to the MEG sensors using an adaptive algorithm. We have demonstrated total ambient noise reduction factors in excess of 10{sup 6} (>120 dB). The residual noise for most MEG SQUID channels is at or near the intrinsic SQUID noise floor, typically 2-3 f T Hz{sup -1/2}. We are recording MEG signals with greater signal-to-noise than equivalent EEG measurements.

  1. Noise-free magnetoencephalography recordings of brain function

    Science.gov (United States)

    Volegov, P.; Matlachov, A.; Mosher, J.; Espy, M. A.; Kraus, R. H., Jr.

    2004-05-01

    Perhaps the greatest impediment to acquiring high-quality magnetoencephalography (MEG) recordings is the ubiquitous ambient magnetic field noise. We have designed and built a whole-head MEG system using a helmet-like superconducting imaging surface (SIS) surrounding the array of superconducting quantum interference device (SQUID) magnetometers used to measure the MEG signal. We previously demonstrated that the SIS passively shields the SQUID array from ambient magnetic field noise, independent of frequency, by 25-60 dB depending on sensor location. SQUID 'reference sensors' located on the outside of the SIS helmet measure ambient magnetic fields in very close proximity to the MEG magnetometers while being nearly perfectly shielded from all sources in the brain. The fact that the reference sensors measure no brain signal yet are located in close proximity to the MEG sensors enables very accurate estimation and subtraction of the ambient field noise contribution to the MEG sensors using an adaptive algorithm. We have demonstrated total ambient noise reduction factors in excess of 106 (>120 dB). The residual noise for most MEG SQUID channels is at or near the intrinsic SQUID noise floor, typically 2-3 f T Hz-1/2. We are recording MEG signals with greater signal-to-noise than equivalent EEG measurements.

  2. Improving Gabor Noise

    OpenAIRE

    Lagae, Ares; Lefebvre, Sylvain; Dutré, Philip

    2011-01-01

    We have recently proposed a new procedural noise function, Gabor noise, which offers a combination of properties not found in existing noise functions. In this paper, we present three significant improvements to Gabor noise: (1) an isotropic kernel for Gabor noise, which speeds up isotropic Gabor noise with a factor of roughly two, (2) an error analysis of Gabor noise, which relates the kernel truncation radius to the relative error of the noise, and (3) spatially varying Gabor noise, which e...

  3. Relativistic Noise

    OpenAIRE

    Kapusta, Joseph; Mueller, Berndt; Stephanov, Misha

    2012-01-01

    The relativistic theory of hydrodynamic fluctuations, or noise, is derived and applied to high energy heavy ion collisions. These fluctuations are inherent in any space-time varying system and are in addition to initial state fluctuations. We illustrate the effects with the boost-invariant Bjorken solution to the hydrodynamic equations. Long range correlations in rapidity are induced by propagation of sound modes. The magnitude of these correlations are directly proportional to the viscositie...

  4. Skewed Noise

    OpenAIRE

    David Dillenberger; Uzi Segal

    2013-01-01

    Experimental evidence suggests that individuals who face an asymmetric distribution over the likelihood of a specific event might actually prefer not to know the exact value of this probability. We address these findings by studying a decision maker who has recursive, non-expected utility preferences over two-stage lotteries. For a binary lottery that yields the better outcome with probability p, we identify noise around p with a compound lottery that induces a probability distribution over t...

  5. 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 evalu

  6. 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...

  7. 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....

  8. Low noise road surfaces

    OpenAIRE

    Bolčina, Matjaž

    2014-01-01

    Noise is everywhere. Noise is a sound that makes people stressful and irritate. It often couses sleep disorders and also health problems like different cardiovascular disorders, hearing loss…In most cases traffic noise is the most disturbing. There are different ways to prevent people from traffic noise like building noise barriers and insulation of facades. However noise barriers and insulation of facades do not prevent noise formation, but are lowering existing noise. Another disadvantage i...

  9. 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.

  10. Nonequilibrium Spin Noise and Noise of Susceptibility

    OpenAIRE

    Schad, Pablo; Narozhny, Boris N.; Schön, Gerd; Shnirman, Alexander

    2014-01-01

    We analyze out-of-equilibrium fluctuations in a driven spin system and relate them to the noise of spin susceptibility. In the spirit of the linear response theory we further relate the noise of susceptibility to a $4$-spin correlation function in equilibrium. We show that, in contrast to the second noise (noise of noise), the noise of susceptibility is a direct measure of non-Gaussian fluctuations in the system. We develop a general framework for calculating the noise of susceptibility using...

  11. Temporal variations in Global Seismic Stations ambient noise power levels

    Science.gov (United States)

    Ringler, A.T.; Gee, L.S.; Hutt, C.R.; McNamara, D.E.

    2010-01-01

    Recent concerns about time-dependent response changes in broadband seismometers have motivated the need for methods to monitor sensor health at Global Seismographic Network (GSN) stations. We present two new methods for monitoring temporal changes in data quality and instrument response transfer functions that are independent of Earth seismic velocity and attenuation models by comparing power levels against different baseline values. Our methods can resolve changes in both horizontal and vertical components in a broad range of periods (∼0.05 to 1,000 seconds) in near real time. In this report, we compare our methods with existing techniques and demonstrate how to resolve instrument response changes in long-period data (>100 seconds) as well as in the microseism bands (5 to 20 seconds).

  12. Inverting seismic noise cross-correlations for noise source distribution: A step towards reducing source-induced bias in seismic noise interferometry

    Science.gov (United States)

    Ermert, Laura; Afanasiev, Michael; Sager, Korbinian; Gokhberg, Alexey; Fichtner, Andreas

    2016-04-01

    We report on the ongoing development of a new inversion method for the space- and time-dependent power spectral density distribution of ambient seismic noise sources. The method, once complete, will mainly serve two purposes: First, it will allow us to construct more realistic forward models for noise cross-correlation waveforms, thereby opening new possibilities for waveform imaging by ambient noise tomography. Second, it may provide new insights about the properties of ambient noise sources, complementing studies based on beamforming or numerical modeling of noise based on oceanographic observations. To invert for noise sources, we consider surface wave signal energy measurements on the 'causal' (station A to B) and on the 'acausal' (station B to A) correlation branch, and the ratio between them. These and similar measurements have proven useful for locating noise sources using cross-correlations in several past studies. The inversion procedure is the following: We construct correlation forward models based on Green's functions from a spectral element wave propagation code. To construct these models efficiently, we use source-receiver reciprocity and assume spatial uncorrelation of noise sources. In such a setting, correlations can be calculated from a pre-computed set of Green's functions between the seismic receivers and sources located at the Earth's surface. We then calculate spatial sensitivity kernels for the noise source distribution with respect to the correlation signal energy measurements. These in turn allow us to construct a misfit gradient and optimize the source distribution model to fit our observed cross-correlation signal energies or energy ratios. We will present the workflow for calculation of the forward model and sensitivity kernels, as well as results for both forward modeling and kernels for an example data set of long-period noise or 'hum' at a global scale. We will also provide an outlook on the noise source inversion considering the

  13. Recent and long-term occupational noise exposure and salivary cortisol level

    DEFF Research Database (Denmark)

    Stokholm, Zara Ann; Hansen, Åse Marie; Grynderup, Matias Brødsgaard;

    2014-01-01

    -term occupational noise exposure and cortisol level measured off work to assess a possible sustained HPA-axis effect. We included 501 industrial, finance, and service workers who were followed for 24h during work, leisure, and sleep. Ambient occupational noise exposure levels were recorded every 5s by personal...... and estimated the noise level at the ear. Salivary cortisol concentration was measured at 20.00h, the following day at awakening, and 30min after awakening on average 5, 14 and 14.5h after finishing work. The mean ambient noise exposure level was 79.9dB(A) [range: 55.0-98.9] and the mean estimated level...... observed no statistically significant exposure response relation between recent, or long-term ambient occupational noise exposure level and any cortisol parameter off work. This was neither the case for recent noise level at the ear. To conclude, neither recent nor long-term occupational noise exposure...

  14. Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit

    International Nuclear Information System (INIS)

    A low noise, low power consumption, compact, ambient temperature signal amplifier for a Cadmium Zinc Telluride (CZT) radiation detector is disclosed. The amplifier can be used within a larger system (e.g., including a multi-channel analyzer) to allow isotopic analysis of radionuclides in the field. In one embodiment, the circuit stages of the low power, low noise amplifier are constructed using integrated circuit (IC) amplifiers , rather than discrete components, and include a very low noise, high gain, high bandwidth dual part preamplification stage, an amplification stage, and an filter stage. The low noise, low power consumption, compact, ambient temperature amplifier enables the CZT detector to achieve both the efficiency required to determine the presence of radionuclides and the resolution necessary to perform isotopic analysis to perform nuclear material identification. The present low noise, low power, compact, ambient temperature amplifier enables a CZT detector to achieve resolution of less than 3% full width at half maximum at 122 keV for a Cobalt-57 isotope source. By using IC circuits and using only a single 12 volt supply and ground, the novel amplifier provides significant power savings and is well suited for prolonged portable in-field use and does not require heavy, bulky power supply components. 9 figs

  15. Ambient oxygen promotes tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Ho Joong Sung

    Full Text Available Oxygen serves as an essential factor for oxidative stress, and it has been shown to be a mutagen in bacteria. While it is well established that ambient oxygen can also cause genomic instability in cultured mammalian cells, its effect on de novo tumorigenesis at the organismal level is unclear. Herein, by decreasing ambient oxygen exposure, we report a ∼50% increase in the median tumor-free survival time of p53-/- mice. In the thymus, reducing oxygen exposure decreased the levels of oxidative DNA damage and RAG recombinase, both of which are known to promote lymphomagenesis in p53-/- mice. Oxygen is further shown to be associated with genomic instability in two additional cancer models involving the APC tumor suppressor gene and chemical carcinogenesis. Together, these observations represent the first report directly testing the effect of ambient oxygen on de novo tumorigenesis and provide important physiologic evidence demonstrating its critical role in increasing genomic instability in vivo.

  16. Mujer y medio ambiente

    OpenAIRE

    Zuluaga Sánchez, Gloria Patricia

    1998-01-01

    El debate sobre mujer y medio ambiente es bastante nuevo y, por lo tanto, aun no hay consenso sobre como abordarlo, ni análisis muy profundos sobre la interacción de estas dos problemáticas tan complejas y que además atraviesan las demás temáticas. Con ello no se quiere negar el importante aporte que se ha hecho en tal sentido, por parte de colectividades y de algunas personas. Selene Herculano y Jacqueline Pitanguy (1993), mencionan que el medio ambiente no es una categoría específica y que ...

  17. La radioactividad ambiental

    Directory of Open Access Journals (Sweden)

    Rafael Núñez-Lagos Roglá

    2011-01-01

    Full Text Available Se explican los conceptos fundamentales relacionados con la radiactividad y se utilizan para describir la radiactividad ambiental. Se explican también los isótopos de largo periodo y las principales familias radioactivas junto con la radiación cósmica y los radionucleidos cosmogénicos.

  18. Inhibitory noise

    Directory of Open Access Journals (Sweden)

    Alain Destexhe

    2010-03-01

    Full Text Available Cortical neurons in vivo may operate in high-conductance states, in which the major part of the neuron's input conductance is due to synaptic activity, sometimes several-fold larger than the resting conductance. We examine here the contribution of inhibition in such high-conductance states. At the level of the absolute conductance values, several studies have shown that cortical neurons in vivo are characterized by strong inhibitory conductances. However, conductances are balanced and spiking activity is mostly determined by fluctuations, but not much is known about excitatory and inhibitory contributions to these fluctuations. Models and dynamic-clamp experiments show that, during high-conductance states, spikes are mainly determined by fluctuations of inhibition, or by inhibitory noise. This stands in contrast to low-conductance states, in which excitatory conductances determine spiking activity. To determine these contributions from experimental data, maximum likelihood methods can be designed and applied to intracellular recordings in vivo. Such methods indicate that action potentials are indeed mostly correlated with inhibitory fluctuations in awake animals. These results argue for a determinant role for inhibitory fluctuations in evoking spikes, and do not support feed-forward modes of processing, for which opposite patterns are predicted.

  19. Noise and Hearing Protection

    Science.gov (United States)

    ... Meeting Calendar Find an ENT Doctor Near You Noise and Hearing Protection Noise and Hearing Protection Patient ... it is. How can I tell if a noise is dangerous? People differ in their sensitivity to ...

  20. Noise-Measuring Method

    DEFF Research Database (Denmark)

    Diamond, J. M.

    1965-01-01

    A noise-measuring method based on the use of a calibrated noise generator and an output meter with a special scale is described. The method eliminates the effect of noise contributions occurring in the circuits following the device under test.......A noise-measuring method based on the use of a calibrated noise generator and an output meter with a special scale is described. The method eliminates the effect of noise contributions occurring in the circuits following the device under test....

  1. 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...

  2. 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...

  3. NIF Ambient Vibration Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Noble, C.R.; Hoehler, M.S., S.C. Sommer

    1999-11-29

    LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B.

  4. NIF Ambient Vibration Measurements

    International Nuclear Information System (INIS)

    LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B

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

    OpenAIRE

    Julius Gineika; Raimondas Grubliauskas

    2012-01-01

    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 frequencie...

  6. Ocean noise in the tropical and subtropical Pacific Ocean.

    Science.gov (United States)

    Sirović, Ana; Wiggins, Sean M; Oleson, Erin M

    2013-10-01

    Ocean ambient noise is well studied in the North Pacific and North Atlantic but is poorly described for most of the worlds' oceans. Calibrated passive acoustic recordings were collected during 2009-2010 at seven locations in the central and western tropical and subtropical Pacific. Monthly and hourly mean power spectra (15-1000 Hz) were calculated in addition to their skewness, kurtosis, and percentile distributions. Overall, ambient noise at these seven sites was 10-20 dB lower than reported recently for most other locations in the North Pacific. At frequencies 200 Hz with higher levels recorded in the winter than in the summer. Several species of baleen whales, humpback (Megaptera novaeangliae), blue (Balaenoptera musculus), and fin (B. physalus) whales, also contributed seasonally to ambient noise in characteristic frequency bands. PMID:24116406

  7. Can Noise Kill People?

    Institute of Scientific and Technical Information of China (English)

    刘玲娣

    2007-01-01

    Someone is singing next door,but you feel unhappy because her singing is just making a noise.We know that too much noise makes people feel terrible. Scientists are still trying to find out more about noise,but already it is known that a noise of over 85 decibels can make some people tired and anxious.

  8. Immersion Into Noise

    OpenAIRE

    Nechvatal, Joseph

    2011-01-01

    Joseph Nechvatal's Immersion Into Noise investigates multiple aspects of cultural noise by applying our audio understanding of noise to the visual, architectual and cognative domains. The author takes the reader through phenomenal aspects of the art of noise into algorithmic and network contexts, beginning in the Abside of the Grotte de Lascaux.

  9. Noise, Health, and Architecture.

    Science.gov (United States)

    Beranek, Leo L.

    There is reasonable agreement that hearing impairment is related to noise exposure. This hearing loss due to noise is considered a serious health injury, but there is still difficulty in delineating the importance of noise related to people's general non-auditory well-being and health. Beside hearing loss, noise inhibits satisfactory speech…

  10. Ambiente il nostro futuro

    OpenAIRE

    Canigiani, Franca

    2016-01-01

    L’ambiente è il quadro di vita, la casa comune, il patrimonio di base delle società umane – scriveva un indimenticabile maestro della geografia italiana: Giuseppe Barbieri. Due gli avvenimenti che nel 2015 hanno segnato il passo dell’umanità sulla strada di una più matura coscienza ambientale, fino a comprendere che è necessario e urgente prendersi cura della Terra: primo, la pubblicazione della lettera enciclica di papa Francesco, Laudato si’ sulla cura della casa comune, straordinario saggi...

  11. AOX y medio ambiente.

    OpenAIRE

    Riva Juan, Mª del Carmen; López Ribas, David

    1996-01-01

    Los productos organohalogenados son muy utilizados por la industria y su presencia en el medio ambiente está siendo controlada. En los últimos años se han desarrollado varias técnicas de detección, siendo desde finales de los 80 los AOX (adsorbable organic halogens) uno de los parámetros sobre los que se han realizado más estudios. En muchos paises de la Unión Europea y en E.E.U.U. de América, la presencia de compuestos organohalogenados en aguas continentales y suelos está legislada indicand...

  12. Arquitectura y medio ambiente

    OpenAIRE

    Saura Carulla, Magdalena

    2003-01-01

    La arquitectura y la planificación son el resultado de una integración ponderada de conocimientos técnicos y una multiplicidad de aspectos relacionados con el conocimiento natural y social. En este trabajo el autor propone, desde el ámbito de las ciencias del medio ambiente, diversos planteamientos teóricos y prácticos relacionados con la arquitectura y el urbanismo. El conocimiento de la naturaleza de los sistemas naturales y de los sistemas ecosociales permite al diseñador aplicar un marco ...

  13. Noise sustained propagation: Local versus global noise

    OpenAIRE

    Locher, M.; Chatterjee, N.; Marchesoni, F.; Ditto, W. L.; Hunt, E. R.

    2000-01-01

    We expand on prior results on noise supported signal propagation in arrays of coupled bistable elements. We present and compare experimental and numerical results for kink propagation under the influence of local and global fluctuations. As demonstrated previously for local noise, an optimum range of global noise power exists for which the medium acts as a reliable transmission ``channel''. We discuss implications for propagation failure in a model of cardiac tissue and present a general theo...

  14. Noise reduction of dental drill noise

    OpenAIRE

    Rotter, KRGR; Atherton, MA; Kaymak, E; Millar, BJ

    2008-01-01

    Dental drills produce a characteristic noise that is uncomfortable for patients and is also known to be harmful to dentists under prolonged exposure. It is therefore desirable to protect the patient and dentist whilst allowing two-way communication, which will require a headphone - type system. Re-establishing good communication between the dentist and patient will be achieved through a combination of three noise cancellation technologies, namely, Passive Noise Control (PNC), Adaptive Filteri...

  15. Active noise cancellation algorithms for impulsive noise

    OpenAIRE

    Li, Peng; Yu, Xun

    2012-01-01

    Impulsive noise is an important challenge for the practical implementation of active noise control (ANC) systems. The advantages and disadvantages of popular filtered-X least mean square (FXLMS) ANC algorithm and nonlinear filtered-X least mean M-estimate (FXLMM) algorithm are discussed in this paper. A new modified FXLMM algorithm is also proposed to achieve better performance in controlling impulsive noise. Computer simulations and experiments are carried out for all three algorithms and th...

  16. Ambient air pollution and annoyance responses from pregnant women

    Science.gov (United States)

    Llop, Sabrina; Ballester, Ferran; Estarlich, Marisa; Esplugues, Ana; Fernández-Patier, Rosalia; Ramón, Rosa; Marco, Alfredo; Aguirre, Amelia; Sunyer, Jordi; Iñiguez, Carmen; INMA-Valencia cohort

    ObjectivesTo describe the degree of annoyance caused by air pollution and noise in pregnant women in a birth cohort; to determine the modifying factors and their relation with exposure to ambient nitrogen dioxide (NO 2). MethodsThe study population was 855 pregnant women in Valencia, Spain. Annoyance caused by air pollution and noise, and explanatory factors were obtained from 786 pregnant women through a questionnaire. NO 2 levels were determined combining measurements at 93 points within the area of study and using geostatistical techniques (kriging). ResultsIn all 7.9% of the women reported high annoyance caused by air pollution and 13.1% high annoyance caused by noise. There was a significant difference in the degree of annoyance due to both air pollution and noise depending on the area where the women lived and their working status. The degree of annoyance correlated better with measured NO 2 at the municipality level (air pollution: r=0.53; noise: r=0.44) than at the individual level (air pollution and noise: r=0.21). On multivariate analysis, being a housewife, higher NO 2 levels and high traffic density were associated with higher degrees of annoyance. ConclusionsThere was a high percentage of women who perceived medium-high annoyance due to noise and air pollution. Annoyance caused by environmental pollutants could lead to some psychological effects, which impair the quality of life, or even physiological ones, which affect prenatal development.

  17. Perception of Noise by Emergency Department Nurses

    Directory of Open Access Journals (Sweden)

    John Graneto

    2013-09-01

    Full Text Available Introduction: Noise in the emergency department (ED may be perceived to be high by both patients and nurses alike. This increased noise level is hypothesized to be responsible for communication interference and subsequent disruption of complex procedures and decision-making. The objective of this study is to quantify ambient noise level in an ED while obtaining coincident subjective surveys from nurses in the assessment of actual versus perceived noise.Methods: Data collected from surveys of ED nurses on each of 3 different dates revealed that sound levels within the selected ED were consistently at or below 70 decibels (dB of sound as measured by a sound level meter. This level of sound is of the same decibel of normal conversation at a 3-5 foot distance. Nurses surveyed overwhelmingly rated noise as “low” or “not loud” irrespective of a variance (though predominantly within a 10 dB range in actual sound decibel measurements.Results: Years of experience of work within emergency departments proved the most consistent predictor of nurses’ opinions on the frequency with which noise levels within the ED were louder than they should be, with more experienced nurses all ranking noise levels as “frequently” or “always” louder than they should be.Conclusion: Individual variance existed in how nurses felt that noise level affected work function. ED nurses��� perception of noise is perceived to be low and generally not interfering with their cognitive function. [West J Emerg Med. 2013;14(5:547–550.

  18. Study on noise prediction model and control schemes for substation.

    Science.gov (United States)

    Chen, Chuanmin; 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.

  19. A comparison of two methods of assessing low frequency noise

    Energy Technology Data Exchange (ETDEWEB)

    Patching, Richard [Patching Associates Acoustical Engineering Ltd (Canada)], email: rpatching@patchingassociates.com

    2011-07-01

    Noise levels are usually measured with varying weighting scales to better adjust to human hear sensibility and these scales are assumed to be inherently appropriate. But this can become a problem when assessing low frequency noise from industrial facilities, and for that matter, Alberta provincial regulations and Canadian federal regulations use different criteria. This paper compares the two methods, and their limits relative to low frequency noise assessment. Alberta noise assessment regulations are based on an absolute permissible sound level, incorporating the ambient noise and added noise from industrial facilities. The Health Canada approach uses a day-night sound level and the criterion for noise annoyance is expressed in terms of the percentage of people highly annoyed by this noise level. Both methods assess low frequency noise the same way, by differentiating the measured A and C-weighted noise levels. And both methods are hard to implement in the design stage of a project for lack of noise information from the manufacturers.

  20. Crisis ambiental y cristianismo

    Directory of Open Access Journals (Sweden)

    Felipe Cárdenas

    2008-01-01

    Full Text Available En el artículo se identifican y reconocen algunas opciones que se pueden desarrollar en el cristianismo en relación con la problemática ambiental. Se aborda el dilema bíblico suscitado por interpretaciones antiecológicas y ecológicas. Con base en una lectura de la Biblia, de testimonios cristianos, y en una rememoria de estructuras institucionales, como la parroquia, se analiza el valor que tiene el mensaje cristiano en lo referido a la mitigación de la crisis ambiental.This article identifies and recognizes some options that can be developed in Christianity in relation to the environmental problem. It starts by analyzing the biblical dilemma provoked by both ecological and antiecological interpretations. Based on a reading of the Bible, testimonies from Christians and with a rememory of institutional structures, like the parish, the valué of the Christian message for mitigating the environmental crisis is analyzed.

  1. Health effects of noise traffic: Beyond 'discomfort'

    Directory of Open Access Journals (Sweden)

    Julio Díaz Jiménez

    2015-12-01

    Full Text Available Noise in the workplace has traditionally been linked to both auditory and non-auditory disorders in people exposed. Recently the noise around airports has been linked to di erent pathologies, primarily cardiovascular-related. In recent years, environmental noise in large cities, due, to a large extent, to tra c, has been linked to various cardiovascular and respiratory diseases, and even to diabetes. In this article, in addition to giving a brief description of studies linking ambient noise and morbidity and of the di erent biological mechanisms involved that may explain these associations, we present the results of a series of studies which link by means of time-series analysis link tra c noise in the city of Madrid and daily mortality for cardiovascular, respiratory and diabetes-related reasons in the group of 65+ year-olds, as well as the annual mortality attributable to tra c noise in Madrid and its comparison with that attributable to PM2.5.

  2. 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.

  3. Types for BioAmbients

    CERN Document Server

    Capecchi, Sara; 10.4204/EPTCS.19.7

    2010-01-01

    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.

  4. 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

  5. Ocean ambient sound south of Bermuda and Panama Canal traffic.

    Science.gov (United States)

    Širović, Ana; Hildebrand, John A; McDonald, Mark A

    2016-05-01

    Comparisons of current and historic ocean ambient noise levels are rare, especially in the North Atlantic. Recent (2013-2014) monthly patterns in ocean ambient sound south of Bermuda were compared to those recorded at the same location in 1966. Additionally, trends in ocean traffic, in particular, Panama Canal traffic, over this time were also investigated. One year of ocean ambient noise measurements were collected in 1966 using cabled, omnidirectional hydrophones at the U.S. Navy Tudor Hill Laboratory in Bermuda, and repeat measurements were collected at the same location from June 2013-May 2014 using a High-frequency Acoustic Recording Package. Average monthly pressure spectrum levels at 44 Hz increased 2.8 ± 0.8 dB from 1966 to 2013, indicating an average increase of 0.6 dB/decade. This low level of increase may be due to topographic shielding at this site, limiting it to only southern exposure, and the limit in the number of ship transits through the Panama Canal, which did not change substantially during this time. The impending expansion of the Canal, which will enable the transit of larger ships at twice the current rate, is likely to lead to a substantial increase in ocean ambient sound at this location in the near future.

  6. Ocean ambient sound south of Bermuda and Panama Canal traffic.

    Science.gov (United States)

    Širović, Ana; Hildebrand, John A; McDonald, Mark A

    2016-05-01

    Comparisons of current and historic ocean ambient noise levels are rare, especially in the North Atlantic. Recent (2013-2014) monthly patterns in ocean ambient sound south of Bermuda were compared to those recorded at the same location in 1966. Additionally, trends in ocean traffic, in particular, Panama Canal traffic, over this time were also investigated. One year of ocean ambient noise measurements were collected in 1966 using cabled, omnidirectional hydrophones at the U.S. Navy Tudor Hill Laboratory in Bermuda, and repeat measurements were collected at the same location from June 2013-May 2014 using a High-frequency Acoustic Recording Package. Average monthly pressure spectrum levels at 44 Hz increased 2.8 ± 0.8 dB from 1966 to 2013, indicating an average increase of 0.6 dB/decade. This low level of increase may be due to topographic shielding at this site, limiting it to only southern exposure, and the limit in the number of ship transits through the Panama Canal, which did not change substantially during this time. The impending expansion of the Canal, which will enable the transit of larger ships at twice the current rate, is likely to lead to a substantial increase in ocean ambient sound at this location in the near future. PMID:27250138

  7. Noise monitoring and modeling on four lanning of national highways corridor.

    Science.gov (United States)

    Devi, P Shiyamala; Rosaline, G Vimala

    2012-10-01

    Noise emitted from traffic contributes to about 55% of total noise pollution in India. This paper is an effort of a research conducted to quantify and analyze the traffic noise emissions along the Salem-Namakkal NH 7 corridor with an ultimate objective of setting up a traffic noise model based on the traffic noise conditions of Indian cities. Noise levels and other variables have been measured in 15 locations to develop a statistical regression model based on A-weighted equivalent noise level for Indian road conditions. The ambient noise levels recorded represent the higher noise levels prevailing along the NH 7 corridor. The Receptor Oriented Technique adopted proves to be helpful in characterizing the ambient noise levels along the study area. The newly developed road traffic noise model can be effectively used as a decision support tool for predicting equivalent noise levels in the cities of India. The present analysis also reveals that the magnitude of noise levels has an increasing trend due to the increased traffic flow and presents the attention needed for minimization. The mitigation measures and the future evaluations are discussed.

  8. Ambient mass spectrometry imaging

    DEFF Research Database (Denmark)

    Janfelt, Christian; Nørgaard, Asger W

    2012-01-01

    Easy ambient sonic spray ionization (EASI) and desorption electrospray ionization (DESI) were used for imaging of a number of samples, including sections of rat brain and imprints of plant material on porous Teflon. A novel approach termed Displaced Dual-mode Imaging was utilized for the direct...... comparison of the two methods: Images were recorded with the individual rows alternating between EASI and DESI, yielding a separate image for each technique recorded under perfectly similar conditions on the same sample. EASI works reliably for imaging of all samples, but the choice of spray solvent and flow...... rate is more critical in tissue imaging with EASI than with DESI. The overall sensitivity of EASI is, in general, slightly lower than that of DESI, and the representation of the dynamic range is different in images of the two techniques for some samples. However, for abundant compounds, EASI works well...

  9. MEIO AMBIENTE E DESENVOLVIMENTO

    OpenAIRE

    Suely Salgueiro Chacon; Daniel Rodriguez de Carvalho Pinheiro; Francisco Correia de Oliveira; Elizabeth Castelo Branco de Souza

    2009-01-01

    O objetivo deste artigo é resgatar elementos para subsidiar uma reflexão crítica sobre o modelo de desenvolvimento econômico prevalente na sociedade e as relações com o meio ambiente, sob a ameaça que ronda o destino da espécie humana, conforme afirmação de Lovelock (2006, p. 20) sobre o conceito de desenvolvimento sustentável: “uma ideia adorável se a tivéssemos aplicado 200 anos atrás, quando havia um bilhão de pessoas no mundo. Agora é tarde demais. Não há mais espaço para nenhum tipo de d...

  10. Reforma constitucional y ambiente

    Directory of Open Access Journals (Sweden)

    Teodoro Bustamante

    2013-09-01

    Full Text Available América Latina está atravesada por una ola de reformas constitucionales. Sus causas, las expectativas que ellas despiertan, los riesgos que se han asociado al proceso de lucha política en su entorno, son temas de un análisis fundamentalmente político; pero hay algunos aspectos en los cuales ese debate tiene una directa repercusión sobre el tema ambiental. En el caso del Ecuador, esto se refleja en el hecho de que una de las innovaciones que se proponen, se refieren a una nueva forma de abordar los temas ambientales, básicamente se establecen Derechos de la Naturaleza.

  11. Nível de ruído no ambiente de trabalho do professor de educação física em aulas de ciclismo indoor Nivel de ruido en el ambiente de trabajo del profesor de educación física en aulas de ciclismo indoor Level of noise at the workplace environment among physical education teachers in indoor bike classes

    OpenAIRE

    Alexandre Palma; Ubirajara A de O Mattos; Marcelo Nunes de Almeida; Giselle Estrella Martins Coelho de Oliveira

    2009-01-01

    OBJETIVO: Analisar o nível de ruído no ambiente de trabalho do professor de educação física durante as aulas de ciclismo indoor e sua associação com alguns aspectos da saúde. MÉTODOS: Estudo transversal conduzido com 15 professores de educação física de diferentes academias de ginástica, na cidade do Rio de Janeiro (RJ), em 2007. As características do processo e da organização do trabalho e as queixas de saúde relatadas pelos professores foram coletadas por meio de questionário padronizado. P...

  12. CCN activation of ambient and "synthetic ambient" urban aerosol

    Science.gov (United States)

    Burkart, Julia; Reischl, Georg; Steiner, Gerhard; Bauer, Heidi; Leder, Klaus; Kistler, Magda; Puxbaum, Hans; Hitzenberger, R.

    2013-05-01

    In this study, the Cloud Condensation Nuclei (CCN) activation properties of the urban aerosol in Vienna, Austria, were investigated in a long term (11 month) field study. Filter samples of the aerosol below 100 nm were taken in parallel to these measurements, and later used to generate "synthetic ambient" aerosols. Activation parameters of this "synthetic ambient" aerosol were also obtained. Hygroscopicity parameters κ [1] were calculated both for the urban and the "synthetic ambient" aerosol and also from the chemical composition. Average κ for the "synthetic ambient" aerosol ranged from 0.20 to 0.30 with an average value of 0.24, while the κ from the chemical composition of this "synthetic ambient" aerosol was significantly higher (average 0.43). The full results of the study are given elsewhere [2,3].

  13. NASA propeller noise research

    Science.gov (United States)

    Greene, G. C.

    1980-01-01

    The research in propeller noise prediction, noise/performance optimization, and interior reduction is described. Selected results are presented to illustrate the status of the technology and the direction of future research.

  14. Modeling deep ocean shipping noise in varying acidity conditions.

    Science.gov (United States)

    Udovydchenkov, Ilya A; Duda, Timothy F; Doney, Scott C; Lima, Ivan D

    2010-09-01

    Possible future changes of ambient shipping noise at 0.1-1 kHz in the North Pacific caused by changing seawater chemistry conditions are analyzed with a simplified propagation model. Probable decreases of pH would cause meaningful reduction of the sound absorption coefficient in near-surface ocean water for these frequencies. The results show that a few decibels of increase may occur in 100 years in some very quiet areas very far from noise sources, with small effects closer to noise sources. The use of ray physics allows sound energy attenuated via volume absorption and by the seafloor to be compared.

  15. Coupling Reduces Noise

    OpenAIRE

    Kia, Behnam; Kia, Sarvenaz; Lindner, John. F.; Sinha, Sudeshna; Ditto, William L.

    2014-01-01

    We demonstrate how coupling nonlinear dynamical systems can reduce the effects of noise. For simplicity we investigate noisy coupled map lattices. Noise from different lattice nodes can diffuse across the lattice and lower the noise level of individual nodes. We develop a theoretical model that explains this observed noise evolution and show how the coupled dynamics can naturally function as an averaging filter. Our numerical simulations are in excellent agreement with the model predictions.

  16. Nonlinear noise cancellation

    OpenAIRE

    Strauch, Paul E

    1997-01-01

    Noise or interference is often assumed to be a random process. Conventional linear filtering, control or prediction techniques are used to cancel or reduce the noise. However, some noise processes have been shown to be nonlinear and deterministic. These nonlinear deterministic noise processes appear to be random when analysed with second order statistics. As nonlinear processes are widespread in nature it may be beneficial to exploit the coherence of the nonlinear deterministic no...

  17. Noise in electromigrated nanojunctions

    OpenAIRE

    Wheeler, P. J.; Chen, Ruoyu; Natelson, D.

    2013-01-01

    Noise measurements are a probe beyond simple electronic transport that can reveal additional information about electronic correlations and inelastic processes. Here we report noise measurements in individual electromigrated nanojunctions, examining the evolution from the many channel regime to the tunneling regime, using a radio frequency technique. While we generally observe the dependence of noise on bias expected for shot noise, in approximately 12% of junction configurations we find discr...

  18. Noise and Neuronal Heterogeneity

    OpenAIRE

    Barber, Michael J.; Ristig, Manfred L.

    2010-01-01

    We consider signal transaction in a simple neuronal model featuring intrinsic noise. The presence of noise limits the precision of neural responses and impacts the quality of neural signal transduction. We assess the signal transduction quality in relation to the level of noise, and show it to be maximized by a non-zero level of noise, analogous to the stochastic resonance effect. The quality enhancement occurs for a finite range of stimuli to a single neuron; we show how to construct network...

  19. Noise in mesoscopic physics

    OpenAIRE

    Martin, Thierry

    2005-01-01

    This is a course on noise which covers some of the scattering theory for normal metals, Hanbury Brown and Twiss analogs for noise correlations with electrons, noise correlations in superconducting/normal metal junctions. Entanglement in such NS systems is described with a criterion for violating Bell inegalities. The last section is devoted to the perturbative derivation of noise in a particular one dimensional correlated electron system (Luttinger liquid): edge states in the fractional quant...

  20. Filtering Solid Gabor Noise

    OpenAIRE

    Lagae, Ares; Drettakis, George

    2011-01-01

    Solid noise is a fundamental tool in computer graphics. Surprisingly, no existing noise function supports both high-quality anti-aliasing and continuity across sharp edges. In this paper we show that a slicing approach is required to preserve continuity across sharp edges, and we present a new noise function that supports anisotropic filtering of sliced solid noise. This is made possible by individually filtering the slices of Gabor kernels, which requires the proper treatment of phase. This ...

  1. Characteristics of USB noise

    Science.gov (United States)

    Gibson, J. S.; Searle, N.

    1976-01-01

    An extensive series of noise measurements, for a variety of geometric and operational parameters, was made on models of upper surface blowing (USB) powered lift systems. The data obtained were analyzed and the effects and trends of parametric variation defined. The behavior and nature of USB noise and the design of USB systems with low noise characteristics is examined.

  2. Noise at the Interface

    DEFF Research Database (Denmark)

    Prior, Andrew

    2011-01-01

    The notion of noise occupies a contested territory, in which it is framed as pollution and detritus even as it makes its opposite a possibility - noise is always defined in opposition to something else, even if this ‘other’ is not quite clear. This paper explores noise in the context of ‘the...

  3. Core Noise - Increasing Importance

    Science.gov (United States)

    Hultgren, Lennart S.

    2011-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system-level noise metrics for the 2015, 2020, and 2025 timeframes; turbofan design trends and their aeroacoustic implications; the emerging importance of core noise and its relevance to the SFW Reduced-Perceived-Noise Technical Challenge; and the current research activities in the core-noise area, with additional details given about the development of a high-fidelity combustor-noise prediction capability as well as activities supporting the development of improved reduced-order, physics-based models for combustor-noise prediction. The need for benchmark data for validation of high-fidelity and modeling work and the value of a potential future diagnostic facility for testing of core-noise-reduction concepts are indicated. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The SFW Reduced-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. This reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. Noise generated in the jet engine core, by sources such as the compressor, combustor, and turbine, can be a significant contribution to the overall noise signature at low-power conditions, typical of approach flight. At high engine power during takeoff, jet and fan noise have traditionally dominated over core noise. However, current design trends and expected technological advances in engine-cycle design as well as noise-reduction methods are likely to reduce non-core noise even at engine-power points higher than approach. In addition, future low-emission combustor

  4. Validating Firewalls in Mobile Ambients

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Hansen, René Rydhof;

    1999-01-01

    The ambient calculus is a calculus of computation that allows active processes (mobile ambients) to move between sites. A firewall is said to be protective whenever it denies entry to attackers not possessing the required passwords. We devise a polynomial time algorithm for rejecting proposed...

  5. Foro Ambiental : CEDENMA, Asamblea Constituyente

    Directory of Open Access Journals (Sweden)

    Anne-Lise Naizot

    2013-09-01

    Full Text Available Resumen de la Mesa redonda: Orientaciones de la nueva Constitución ecuatoriana en materia ambiental: ¿avances o retrocesos en relación con el marco político y filosófico ambiental vigente en algunos países de la región?

  6. Low-noise amplifier

    OpenAIRE

    V. B. Gulkov; A. S. Makarenko

    2012-01-01

    The mixture of signal and noise processing device is considered in this article. It contains two channels: the main channel (MC) contains the mixture of signal and noise, and compensation channel (CC) that extracts just a noise from the mixture. The feature of the processing circuit is that the mixture samples are formed by short impulses at the moments of passing signal through zero. Further antiphase noise is set in the channels, adder by which the noise is removed from mixture is set on th...

  7. Compression by Noise Equalization

    OpenAIRE

    Jähne, Bernd

    2013-01-01

    For any relation of the noise variance with the gray value, a nonlinear transform h(g) can be applied so that the variance of the transformed signal h is constant. The number of bits required to represent the noise-equalized signal is in good approximation equal to the maximum signal/noise ratio (SNRmax). Thus the noise-equalized signal of any imaging sensor with a full-well capacity of less than 2^16 can be represented by only 8 bit or less with only a slight increase in the overall noise le...

  8. 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....

  9. Decreasing the uncertainty of atomic clocks via real-time noise distinguish

    CERN Document Server

    Dong, Richang; Wei, Rong; Wang, Wenli; Zou, Fan; Du, Yuanbo; Chen, Tingting; Wang, Yuzhu

    2016-01-01

    The environmental perturbation on atoms is the key factor restricting the performance of atomic frequency standards, especially in long term scale. In this letter, we demonstrate a real-time noise distinguish operation of atomic clocks. The operation improves the statistical uncertainty by about an order of magnitude of our fountain clock which is deteriorated previously by extra noises. The frequency offset bring by the extra noise is also corrected. The experiment proves the real-time noise distinguish operation can reduce the contribution of ambient noises and improve the uncertainty limit of atomic clocks.

  10. New Neural Procedure for Extraction of Parameters of Microwave FET Noise Models

    Directory of Open Access Journals (Sweden)

    N. Ivković

    2013-11-01

    Full Text Available A neural netwok based procedure for extraction of parameters of microwave FET noise models is proposed in this paper. The procedure is illustrated on the Pospieszalski’s noise model. A neural network is trained to predict the equivalent drain noise temperature for given values of the intrinsic circuit elements, intrinsic noise parameters, ambient temperature and frequency. In this way, the repeated extraction procedures in microwave circuit simulators are avoided. The presented approach is validated on a specific HEMT device noise modeling. The results are compared with the results obtained for the model parameters extracted by using the standard optimization based extraction procedures.

  11. A normalized data-reusing least-mean-square algorithm of noise cancellation for magnetocardiography

    Institute of Scientific and Technical Information of China (English)

    Kong Xiang-Yan; Wang Hui-Wu; Tian Ye; Huang Xu-Guang; Zhang Li-Hua; Ren Yu-Feng; Chen Geng-Hua; Yang Qian-Sheng

    2004-01-01

    An adaptive filter based on Data-Reusing Least-Mean-Square algorithm has been proposed and applied in magnetocardiography (MCG) to suppress ambient noise. Numerical simulation studies indicate that the adaptive filter is a powerful noise suppresser for correlated interferences, especially for those with amplitude changing and time delay.Also the filter has a wide frequency bandwidth. With this filter, the signal-to-noise ratio of an MCG is improved to the intrinsic noise level. The periodic average method for further improvement of the noise level in MCG is also discussed.

  12. Potential Uses of Anthropogenic Noise as a Source of Information in Animal Sensory and Communication Systems.

    Science.gov (United States)

    Stansbury, Amanda; Deecke, Volker; Götz, Thomas; Janik, Vincent M

    2016-01-01

    Although current research on the impact of anthropogenic noise has focused on the detrimental effects, there is a range of ways by which animals could benefit from increased noise levels. Here we discuss two potential uses of anthropogenic noise. First, local variations in the ambient-noise field could be used to perceive objects and navigate within an environment. Second, introduced sound cues could be used as a signal for prey detection or orientation and navigation. Although the disadvantages of noise pollution will likely outweigh any positive effects, it is important to acknowledge that such changes may benefit some species. PMID:26611074

  13. Magnetic flux noise in copper oxide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, M.J.

    1991-11-01

    Magnetic flux noise and flux creep in thin films and single crystals of YBa{sub 2}Cu{sub 3}O{sub 7-x}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}, Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub x}, and TlCa{sub 2}Ba{sub 2}Cu{sub 3}O{sub x} are measured with a superconducting quantum interference device (SQUID). The noise power spectrum generally scales as 1/f (f is frequency) from 1 Hz to 1 kHz, increases with temperature, and decreases in higher-quality films. It is proportional to the magnetic field B in which the sample is cooled, at least in the range 0.1 mT < B < 3 mT. A model of thermally activated vortex motion is developed which explains the dependence of the noise on frequency, temperature, current, and applied magnetic field. The pinning potential is idealized as an ensemble of double wells, each with a different activation energy separating the two states. From the noise measurements, this model yields the distribution of pinning energies in the samples, the vortex hopping distance, the number density of mobile vortices, and the restoring force on a vortex at a typical pinning site. The distribution of pinning energies in YBa{sub 2}Cu{sub 3}O{sub 7-x} shows a broad peak below 0.1 eV. The small ambient magnetic field, and the detection of noise even in the absence of a driving force, insure that the measured pinning energies are characteristic of isolated vortices near thermal equilibrium. The observed vortex density in fields much less than 0.1 mT is too large to be explained by the ambient field, suggesting a mechanism intrinsic to the sample which produces trapped vortices.

  14. Low-noise amplifier

    Directory of Open Access Journals (Sweden)

    V. B. Gulkov

    2012-11-01

    Full Text Available The mixture of signal and noise processing device is considered in this article. It contains two channels: the main channel (MC contains the mixture of signal and noise, and compensation channel (CC that extracts just a noise from the mixture. The feature of the processing circuit is that the mixture samples are formed by short impulses at the moments of passing signal through zero. Further antiphase noise is set in the channels, adder by which the noise is removed from mixture is set on the cannels output. Study of the described device was carried out for simulated AM signal and white Gaussian noise in simulation environment Matlab. The results are shown, that device reduces noise by 16 dB of power.

  15. Nuclear Spin Noise and STM Noise Spectroscopy

    OpenAIRE

    Balatsky, A. V.; Fransson, J.; Mozyrsky, D.; Manassen, Yishay

    2006-01-01

    We consider fluctuations of the electronic spin due to coupling to nuclear spin. Noise spectroscopy of an electronic spin can be revealed in the Scanning Tunnelling Microscope (STM). We argue that the noise spectroscopy of electronic spin can reveal the nuclear spin dynamics due to hyperfine coupling. Tunnelling current develops satellites of the main lines at Larmor frequency and at zero frequency due to hyperfine coupling. We also address the role of the rf field that is at or near the reso...

  16. Aspectos computacionais do ambiente IMAGUS

    OpenAIRE

    Raabe, André Luís Alice; Giraffa, Lúcia Maria Martins

    2000-01-01

    Este artigo apresenta a descrição do ambiente IMAGUS enfatizando aspectos da implementação do protótipo do ambiente. O IMAGUS permite a construção de materiais com fins pedagógicos que se utilizam de vídeos acessado via Internet. O protótipo foi desenvolvido para validar a arquitetura proposta para o ambiente. São apresentadas as soluções a nível de modelagem e a implementação do protótipo baseada na utilização da interface Java Media Framework

  17. Urban Noise Protection

    Science.gov (United States)

    Jäcker-Cüppers, Michael

    Noise belongs to the severest environmental impairments in towns, with road traffic being the most annoying noise source. The reduction of these impairments and the precaution against new noise impacts is an important task of the communities. However, many of the potential abatement measures are not in the responsibility of the communities. In most European countries, noise emission regulations for road and rail vehicles and outdoor machinery are nowadays enforced by the European Union. Noise reception limits are generally enforced by national laws. Therefore, efficient noise abatement in towns has to be coordinated with the regional, national and supranational, i.e. European noise policy. The most important fields of action for the urban noise abatement are the roads, railways and airports with heavy traffic. For the avoidance of health risks due to noise here short-term reductions are needed, which can generally be achieved only by a combination of measures for which different stakeholders are responsible. This underlines the importance of integrated and coordinated noise abatement concepts.

  18. Measuring and interpreting the mechanical thermal noise spectrum in a MEMS

    Science.gov (United States)

    Rocha, L. A.; Cretu, E.; Wolffenbuttel, R. F.

    2005-07-01

    The meta-stability of the pull-in displacement of an electrostatically operated parallel plate micromechanical structure is used for the capacitive measurement of the mechanical-thermal noise spectrum in a MEMS. Pull-in time depends on force and is not affected by the input-referred noise of the readout circuit. Repeatedly bringing the microstructure to pull-in while measuring the pull-in time followed by FFT enables the measurement of the mechanical noise spectrum with a non-mechanical noise level set primarily by the resolution of the time measurement. The white noise level is found to be in agreement with the theory on damping. The 1/f noise spectrum is found to be independent of ambient gas pressure with a 1/f noise-white noise cross-over frequency at 0.007 Hz for a 1 bar gas pressure and is reproducible for devices fabricated in the same process and the same run.

  19. 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.

  20. 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. PMID:26611036

  1. Industrial wideband noise reduction for hearing aids using a headset with adaptive-feedback active noise cancellation.

    Science.gov (United States)

    Lin, J H; Li, P C; Tang, S T; Liu, P T; Young, S T

    2005-11-01

    High-intensity noises are a health hazard for industrial workers, and hearing protection is necessary to prevent hearing loss. Passive methods, such as ear muffs, are ineffective against low-frequency noise. Moreover, many hearing-impaired workers must wear hearing aids to enable communication at their workplace, and such aids can amplify ambient noise. To overcome this problem, the present study developed a headset equipped with a digital signal processing system to implement adaptive-feedback active noise cancellation (AFANC) to reduce low-frequency noise. The proposed AFANC headset was effective against wideband industrial noise, with a maximum noise spectrum power reduction of 30 dB. Furthermore, when used with a hearing aid, it improved the speech signal-to-noise ratio by up to 14 dB. These results suggest that a headset with AFANC would be useful for hearing protection in workplaces with high levels of low-frequency industrial noise, especially for hearing-impaired workers. PMID:16594300

  2. Adaptive noise cancellation

    CERN Document Server

    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.

  3. Mitigation of calorimeter noise.

    Energy Technology Data Exchange (ETDEWEB)

    Santi, P. A. (Peter A.); Bracken, D. S. (David S.); Smith, M. K. (Morag K.)

    2004-01-01

    One of the main factors that limit the sensitivity of calorimeters is the noise in the calorimeter response. A previous study into the sources of noise in a Wheatstone bridge calorimeter used by Department of Energy (DOE) facilities has shown that the control system for maintaining the water bath at a constant temperature was an important contributor to the noise in the system. In order to minimize the contribution that the control system makes to the noise in the calorimeter response, a new control system for the calorimeter has been developed. An experimental and analytical study has been performed to determine the effectiveness of this new control system in reducing the response noise in a Wheatstone bridge calorimeter. The results of this study are presented along with their implications for future work in minimizing the equilibrium noise of calorimeters.

  4. Word Identification in Noise

    OpenAIRE

    Pisoni, David B.

    1996-01-01

    Speech intelligibility has traditionally been measured by presenting words mixed in noise to listeners for identification at several different signal-to-noise ratios. The words are produced in isolation or in sentence contexts where the predictability of specific items can be varied. Psychometric functions are typically obtained relating signal-to-noise ratio to percent correct recognition. Error analyses are often carried out by examining response confusions to construct similarity spaces fo...

  5. Multidimensional Speckle Noise Model

    OpenAIRE

    Fàbregas Xavier; López-Martínez Carlos; Pottier Eric

    2005-01-01

    One of the main problems of SAR imagery is the presence of speckle noise, originated by the inherent coherent nature of this type of systems. For one-dimensional SAR systems it has been demonstrated that speckle can be considered as a multiplicative noise term. Nevertheless, this simple model cannot be exported when multidimensional SAR imagery is addressed. This paper is devoted to present the latest advances into the definition of a multidimensional speckle noise model which does not depen...

  6. Nuclear spin noise imaging

    OpenAIRE

    Müller, Norbert; Jerschow, Alexej

    2006-01-01

    NMR images were obtained from the proton spin noise signals of a water-containing phantom, which was placed in the highly tuned, low-noise resonant circuit of a cryogenically cooled NMR probe in the presence of systematically varied magnetic field gradients. The spatially resolved proton spin density was obtained from the raw signal by a modified projection–reconstruction protocol. Although spin noise imaging is inherently less sensitive than conventional magnetic resonance imaging, it afford...

  7. Aircrafts' taxi noise emission

    OpenAIRE

    Asensio Rivera, César; Pagán Muñoz, Raúl; López Navarro, Juan Manuel

    2008-01-01

    During planning stages, when noisy activity has not been implanted or while evaluating operation changes, it is necessary to find an environmental noise mapping prediction tool for future scenarios. When an activity is already implanted, it is possible to measure noise emissions, but this is expensive, so prediction tools can also be useful. Because of these reasons, for the last 10 years, as a response to the increasing concern for noise pollution in developed countries, several simulation m...

  8. Acceptable noise level

    DEFF Research Database (Denmark)

    Olsen, Steen Østergaard; Nielsen, Lars Holme; Lantz, Johannes;

    2012-01-01

    The acceptable noise level (ANL) is used to quantify the amount of background noise that subjects can accept while listening to speech, and is suggested for prediction of individual hearing-aid use. The aim of this study was to assess the repeatability of the ANL measured in normal-hearing subjec...... using running Danish and non-semantic speech materials as stimuli and modulated speech-spectrum and multi-talker babble noises as competing stimuli....

  9. Toward Forecasting Volcanic Eruptions using Seismic Noise

    CERN Document Server

    Brenguier, Florent; Campillo, Michel; Ferrazzini, Valerie; Duputel, Zacharie; Coutant, Olivier; Nercessian, Alexandre

    2007-01-01

    During inter-eruption periods, magma pressurization yields subtle changes of the elastic properties of volcanic edifices. We use the reproducibility properties of the ambient seismic noise recorded on the Piton de la Fournaise volcano to measure relative seismic velocity variations of less than 0.1 % with a temporal resolution of one day. Our results show that five studied volcanic eruptions were preceded by clearly detectable seismic velocity decreases within the zone of magma injection. These precursors reflect the edifice dilatation induced by magma pressurization and can be useful indicators to improve the forecasting of volcanic eruptions.

  10. Partially informed noise traders

    OpenAIRE

    Aase, Knut K.; Bjuland, Terje; Øksendal, Bernt

    2012-01-01

    The single auction equilibrium of Kyle’s (1985) is studied, in which noise traders may be partially informed, or alternatively they can be manipulated. Unlike Kyle’s assumption that the quantity traded by the noise traders is independent of the asset value, we assume that the noise traders are able to correlate their trade with the true price. This has several implications for the equilibrium, one being that the informed trader’s expected profits decrease as the noise traders’ ability to corr...

  11. On 1/f Noise

    OpenAIRE

    Li, Ming; Zhao, Wei

    2012-01-01

    Due to the fact that 1/f noise gains the increasing interests in the field of biomedical signal processing and living systems, we present this introductive survey that may suffice to exhibit the elementary and the particularities of 1/f noise in comparison with conventional random functions. Three theorems are given for highlighting the particularities of 1/f noise. The first says that a random function with long-range dependence (LRD) is a 1/f noise. The secondindicates that a heavy-tailed r...

  12. Noise through Quantum Pumps

    OpenAIRE

    Polianski, M. L.; Vavilov, M. G.; Brouwer, P.W.

    2002-01-01

    We study the current noise through an unbiased quantum electron pump and its mesoscopic fluctuations for arbitrary temperatures and beyond the bilinear response. In the bilinear regime, we find the full distributions of the noise power and the current-to-noise ratio for a chaotic quantum dots with single-channel and many-channel ballistic point contacts. For a dot with many-channel point contacts we also calculate the ensemble-averaged noise at arbitrary temperature and pumping strength. In t...

  13. Landing gear noise attenuation

    Science.gov (United States)

    Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)

    2011-01-01

    A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

  14. 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.

  15. Noise and Health: How does noise affect us?

    NARCIS (Netherlands)

    Miedema, H.M.E.

    2001-01-01

    Noise annoyance is a primary indication that noise is a problem, and by itself noise annoyance means that the quality of life is adversely affected. Results from noise annoyance research are presented that make possible a detailed evaluation of noise exposures with respect to the annoyance induced.

  16. 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…

  17. 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...

  18. Enhancement of the low-intensity noise generator efficiency

    Directory of Open Access Journals (Sweden)

    A. F. Yanenko

    2013-07-01

    Full Text Available Introduction. The low-intensity noise generators of millimeter wavelength range find wide application in the engineering, biological appliance and therapy procedures due to the simplicity, reliability and efficiency at treatment of pain syndromes in the different branches of practical medicine. Design of the low-intensity noise generator. The features of low-intensity noise generator are electromagnetic waves generation by means of the radiation source (working substance that has a temperature more or less of the environment ambient temperature. Structurally the radiation source is made as a millimeter range waveguide matched load. It is enclosed and heat-insulated. One of basic lacks of similar noise generators is small initial power. Authors have proposed two variant of the noise generator power increasing. Their experimental stud-ies results and choice of natural origin (minerals materials prompt are undertaken for the working substance of thermal generator and more effective construction of cool element of-fers. Enhancement of the noise generator power. Utilization of mineral (for example, nephrite as working substance provides the double increase of noise initial signal power in comparison with standard material – ferroepoxide usually used in microwave technique. The multi-layered construction of Peltier element provides the value of working substance temperature in range 20-30оС accordingly increases power of negative electromagnetic stream. Conclusion. Thus the proposed low-intensity noise generator design provides greater efficiency at its use in the engineering, biological appliance and therapy procedures of practical medicine.

  19. MOWER ATTACHMENT NOISE

    OpenAIRE

    Mosdzianowski, G.

    1990-01-01

    The noise produced by grass mowing attachments fitted to small tractors and combining a number of rotary blades with a total cutting width of up to 120 cm was investigated. The paper develops a noise reduction concept based on an analysis of sound sources.

  20. Noise-induced linearisation

    OpenAIRE

    Dykman, Mark; Luchinsky, D. G.; Mannella, R.; McClintock, Peter V. E.; Short, H. E.; Stein, N. D.; Stocks, N. G.

    1994-01-01

    It is found that the response of a nonlinear dynamical system can be linearised, and its frequency dispersion diminished, by the addition of external noise of sufficient intensity. Taking as an example an overdamped bistable system driven by a low-frequency periodic field, this noise-induced linearisation is investigated through analogue electronic experiments. The wider implications are considered.

  1. Mediality is Noise

    DEFF Research Database (Denmark)

    Prior, Andrew

    This PhD is concerned with the use of noise as a material within media arts practice, especially in ‘post-digital’ contexts such as glitch electronica, glitch art and uses of old media. It examines the relationship between informational culture and noise, exploring the ways in which the structuring...

  2. Acceptable noise level

    DEFF Research Database (Denmark)

    Olsen, Steen Østergaard; Nielsen, Lars Holme; Lantz, Johannes;

    2012-01-01

    The acceptable noise level (ANL) is used to quantify the amount of background noise that subjects can accept while listening to speech, and is suggested for prediction of individual hearing-aid use. The aim of this study was to assess the repeatability of the ANL measured in normal-hearing subjects...

  3. Noise Pollution, Teachers' Edition.

    Science.gov (United States)

    O'Donnell, Patrick A.; Lavaroni, Charles W.

    One of three in a series about pollution, this teacher's guide for a unit on noise pollution is designed for use in junior high school grades. It offers suggestions for extending the information and activities contained in the textual material for students. Chapter 1 discusses the problem of noise pollution and involves students in processes of…

  4. EDA noise analysis

    International Nuclear Information System (INIS)

    Using orCAD Pspice EDA software, the circuit simulation and the analysis such as transient analysis, noise analysis, temperature analysis, are made for charge-sensitive preamplifier. By calculation and comparison, the result shows circuit noise responses according to the temperature changes. (authors)

  5. Low-noise gallium-arsenide field-effect transistor preamplifiers for stochastic beam cooling systems

    International Nuclear Information System (INIS)

    The present noise performance, bandwidth capability and gain stability of bipolar and field-effect transistors, parametric amplifier, Schottky diode mixer and maser are summarized and compared in the 100 MHz to 40 GHz frequency range for stochastic beam cooling systems. Stability factor of GaAs FET's as a function of ambient temperature is presented and discussed. Performance data of several low-noise wide-band cryogenically cooled preamplifiers are presented including one with a noise figure of 0.35 dB over a bandwidth range of 150500 MHz operating at ambient temperature of 200K. Also, data are given on a broadband 1-2 GHz preamplifier having a noise figure of approximately 0.2 dB. The gain, operating noise temperature, stability, gain nonuniformity and phase-shift as function of frequency of interest for beam cooling systems are discussed

  6. The spatial structure of underwater noise due to shipping activities in the Celtic Sea

    Science.gov (United States)

    Chen, Feng; Shapiro, Georgy; Thain, Richard

    2014-05-01

    Underwater noise is now classed as pollution alongside chemical pollution and marine litter (MSFD, 2012). Underwater noise from man-made sources arises from a number of sources including shipping activities. There are numerous examples of sound-induced effects recorded for various marine mammals, either in controlled situations, or opportunistically (MSFD-GES, 2012). Broad or narrow band continuous sounds, as well as pulses, have been documented to cause effects ranging from slight behaviour change, to activity disruption, avoidance or abandonment of preferred habitat (see Clark et al., 2009). Underwater ambient noise generated by shipping activities has increased significantly over the past decades (e.g. Mcdonald et al., 2006). Noise from shipping is a major contributor to the ambient noise levels in ocean, particularly at low (

  7. EXTRACTING MODAL PARAMETERS FROM STRUCTURES UNDERGOING AMBIENT EXCITATION

    Institute of Scientific and Technical Information of China (English)

    华宏星; 陈之炎; 傅志方; 李中付; 宋汉文

    2001-01-01

    On Line Parameter Identification Technique (OLPIT) was presented according to ambient excitation characteristics and the response cross-correlation function that is a sum of decaying sinusoids of the same form as the impulse response function of the original system. OLPIT is a new method of identification modal parameters from response of structures under ambient excitation. OLPIT is different from NExT (natural excitation technique) based on ITD method in four aspects: ① The algorithm is improved by the singular-value decomposition (SVD). ② Multi-value of br in the Ibrahim Time Domain (ITD) is avoided. ③ OLPIT is used in both SIMO (single input, multi-output) and MIMO (multi input, multi-output). ④ The precision of modal parameter identificatioin is improved. The simulation studies demonstrate that the method is effective in identifying complex modes even with close frequencies and is robust to measurement noise.

  8. Research on strategy marine noise map based on i4ocean platform: Constructing flow and key approach

    Science.gov (United States)

    Huang, Baoxiang; Chen, Ge; Han, Yong

    2016-02-01

    Noise level in a marine environment has raised extensive concern in the scientific community. The research is carried out on i4Ocean platform following the process of ocean noise model integrating, noise data extracting, processing, visualizing, and interpreting, ocean noise map constructing and publishing. For the convenience of numerical computation, based on the characteristics of ocean noise field, a hybrid model related to spatial locations is suggested in the propagation model. The normal mode method K/I model is used for far field and ray method CANARY model is used for near field. Visualizing marine ambient noise data is critical to understanding and predicting marine noise for relevant decision making. Marine noise map can be constructed on virtual ocean scene. The systematic marine noise visualization framework includes preprocessing, coordinate transformation interpolation, and rendering. The simulation of ocean noise depends on realistic surface. Then the dynamic water simulation gird was improved with GPU fusion to achieve seamless combination with the visualization result of ocean noise. At the same time, the profile and spherical visualization include space, and time dimensionality were also provided for the vertical field characteristics of ocean ambient noise. Finally, marine noise map can be published with grid pre-processing and multistage cache technology to better serve the public.

  9. Ambiente juvenil: discurso ambiental entre jóvenes universitarios

    OpenAIRE

    Quinn-Anderson, William C.

    2008-01-01

    Esta tesis pretende hacer una aportación al conocimiento del medio ambiente del occidente de México, específicamente de la zona metropolitana de Guadalajara, a partir del estudio de la cultura ambiental manifestada en el discurso de los jóvenes universitarios del ITESO. La apuesta es que puede ser provechoso considerar dentro del concepto de “medio ambiente” no solamente componentes bióticos y abióticos, sino también elementos socioculturales como cultura y significado. Es evidente que hay in...

  10. Size-dependent physiological responses of shore crabs to single and repeated playback of ship noise.

    Science.gov (United States)

    Wale, Matthew A; Simpson, Stephen D; Radford, Andrew N

    2013-04-23

    Anthropogenic noise has fundamentally changed the acoustics of terrestrial and aquatic environments, and there is growing empirical evidence that even a single noise exposure can affect behaviour in a variety of vertebrate organisms. Here, we use controlled experiments to investigate how the physiology of a marine invertebrate, the shore crab (Carcinus maenas), is affected by both single and repeated exposure to ship-noise playback. Crabs experiencing ship-noise playback consumed more oxygen, indicating a higher metabolic rate and potentially greater stress, than those exposed to ambient-noise playback. The response to single ship-noise playback was size-dependent, with heavier crabs showing a stronger response than lighter individuals. Repeated exposure to ambient-noise playback led to increased oxygen consumption (probably due to handling stress), whereas repeated exposure to ship-noise playback produced no change in physiological response; explanations include the possibility that crabs exhibited a maximal response on first exposure to ship-noise playback, or that they habituated or become tolerant to it. These results highlight that invertebrates, like vertebrates, may also be susceptible to the detrimental impacts of anthropogenic noise and demonstrate the tractability for more detailed investigations into the effects of this pervasive global pollutant.

  11. Conhecimento, interdisciplinaridade e Psicologia Ambiental

    Directory of Open Access Journals (Sweden)

    Ombretta Romice

    2005-01-01

    Full Text Available Responde às questões - como os métodos da Psicologia Ambiental devem ser discutidos em um enquadramento interdisciplinar; a Psicologia Ambiental pede alguma abordagem metodológica especial; como a intervenção ambiental é determinada pela interdisciplinaridade; quais são estas disciplinas e como elas se relacionam entre si - baseando-se em experiências profissionais como orientador em um projeto com comunidade, com habitação popular e exclusão social em vários países da Europa, e como consultora. Conclui que as abordagens usadas pelas diferentes profissões são muito separadas, e que apenas metas comuns não são suficientes, sendo também necessários um treino conjunto e identidade de valores.

  12. Substation noise screening tool

    Energy Technology Data Exchange (ETDEWEB)

    Maybee, Nigel; Everton, Pascal [HFP Acoustical Consultants Corp. (Canada)], email: nigel.maybee@hfpacoustical.com; Chow, Vincent [Altalink Management Ltd. (Canada)], email: Vincent.Chow@AltaLink.ca

    2011-07-01

    Alberta noise regulations require energy-related facilities to conduct predictions on sound levels, especially for large and medium noise sources. This is usually done with well-known modelling software, but that can be disadvantageous when assessing the noise impact of smaller noise sources, such as transformer substations. This paper focuses on the development of a spreadsheet substation noise screening tool to assess the noise impact of a small transformer substation with precision and ease-of-use. Three aspects must be considered: transformer sound levels, which can be provided by the manufacturer or extracted from accepted sound level references; sound power calculations, which depend on the substation size and operating regime; and sound propagation calculations, which take into account the distance of the receptor from the substation and sound absorption by the air and ground. Comparison of results obtained with this tool with results generated by standard sound modelling software shows the utility, accuracy and ease-of-use of this screening method for assessing the noise impact of transformer substations.

  13. Noise and Hearing Loss Prevention

    Science.gov (United States)

    ... Follow us on Twitter Noise Manufacturing Construction SafeInSound Noise and Hearing Loss on the NIOSH Science Blog ... Topics Publications and Products Programs Contact NIOSH NIOSH NOISE AND HEARING LOSS PREVENTION Recommend on Facebook Tweet ...

  14. Ambient cosmology and spacetime singularities

    CERN Document Server

    Antoniadis, Ignatios

    2015-01-01

    We present a new approach to the issues of spacetime singularities and cosmic censorship in general relativity. This is based on the idea that standard 4-dimensional spacetime is the conformal infinity of an ambient metric for the 5-dimensional Einstein equations with fluid sources. We then find that the existence of spacetime singularities in four dimensions is constrained by asymptotic properties of the ambient 5-metric, while the non-degeneracy of the latter crucially depends on cosmic censorship holding on the boundary.

  15. Ambient cosmology and spacetime singularities

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, Ignatios [Bern University, Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern (Switzerland); Ecole Polytechnique, Palaiseau (France); Cotsakis, Spiros [CERN, Theory Division, Department of Physics, Geneva 23 (Switzerland); National Technical University, School of Applied Mathematics and Physical Sciences, Athens (Greece)

    2015-01-01

    We present a new approach to the issues of spacetime singularities and cosmic censorship in general relativity. This is based on the idea that standard 4-dimensional spacetime is the conformal infinity of an ambient metric for the 5-dimensional Einstein equations with fluid sources. We then find that the existence of spacetime singularities in four dimensions is constrained by asymptotic properties of the ambient 5-metric, while the non-degeneracy of the latter crucially depends on cosmic censorship holding on the boundary. (orig.)

  16. Medio ambiente y responsabilidad social

    OpenAIRE

    Roa Buitrago, Rosa Isabel

    2012-01-01

    Las organizaciones, dentro de los procesos de responsabilidad social y con el fin de mejorar la calidad de vida de las comunidades que impactan, han optado por proteger y preservar el medio ambiente de acuerdo a ciertos protocolos y normas internacionales que generan una cultura al respecto. Este cuaderno de investigación aborda la norma ISO 26000, la cual asume el tema de la Responsabilidad Social Empresarial (RSE) en materia de medio ambiente y es una guía para ser implementada en las orga...

  17. Los estudios sobre el ambiente y la ciencia ambiental

    Directory of Open Access Journals (Sweden)

    Amelia Nancy Giannuzzo

    2010-03-01

    Full Text Available La existencia de la ciencia ambiental es reconocida en libros, revistas de publicación científica y carreras de grado y posgrado. Sin embargo, se desconoce su existencia en forma literal o indirecta, al no ser considerado su aporte, por ejemplo, en los planteos referidos sobre la ciencia y la tecnología de la sustentabilidad. En este trabajo se presentan estos antecedentes, relacionándolos con el objetivo del mismo, que es el de aportar a la dilucidación de la existencia y conformación de la ciencia ambiental. Para esto, se analiza la relación de las disciplinas con la dimensión compleja del ambiente como objeto de estudio y aspectos metodológicos derivados. A los fines de aportar al esclarecimiento conceptual, se identifican las distintas acepciones de ambiente comúnmente referidas en la bibliografía. Además, se discuten aspectos relacionados de multidisciplinariedad, interdisciplinariedad y transdisciplinariedad, y sobre el status epistémico de la ciencia ambiental. Se concluye que una mayor precisión conceptual embasada en un marco compartido por las disciplinas que estudian el ambiente, incluida la ciencia ambiental, y los distintos actores involucrados en las problemáticas ambientales, favorecerá el refinamiento de las metodologías tendientes a disminuir la fragmentación de las investigaciones concernientes y las aplicaciones para su resolución.The existence of an environmental science is recognized in books, journals of science as well as in undergraduate and graduate studies. Its existence, however, is unknown either literally or indirectly when, for instance, its contribution to topics connected to the science and technology of sustainability is not considered. This background is presented in this paper and connected to its objective, which is to elucidate the existence and structure of the environmental science. To this goal, I analyse the relationship of the disciplines with the complex dimension of the environment

  18. Constructing a global noise correlation database

    Science.gov (United States)

    Ermert, L. A.; Fichtner, A.; Sleeman, R.

    2013-12-01

    We report on the ongoing construction of an extensive global-scale database of ambient noise cross-correlation functions spanning a frequency range from seismic hum to oceanic microseisms (roughly 2 mHz to 0.2 Hz). The database - ultimately to be hosted by ORFEUS - will be used to study the distribution of microseismic and hum sources, and to perform multiscale full waveform inversion for crustal and mantle structure. To build the database, we acquire continuous time series data from permanent and temporary networks hosted mostly at IRIS and ORFEUS. We process and correlated the time series using a fully parallelised tool based on the Python package Obspy. Processing follows two main flows: We obtain both classical cross-correlation functions and phase cross-correlation functions. Phase cross-correlation is an amplitude-independent measure of waveform similarity. Either type of correlation can be used for the inversions. We stack individual time windows linearly. Additionally, we calculate the stack of instantaneous phases of the analytic cross-correlation signal, which can be included as optional processing step. Multiplying the linear stack by the phase stack downweights those parts of the linear stack that show little phase coherency. Thus, it accelerates the emergence of weak coherent signals, which is of particular importance for the processing of data from recently deployed or temporary stations that have only been recording for a short time. Obtaining and processing data for such a massive database requires considerable computational resources, offered by the Swiss National Supercomputing Centre (CSCS) in the form of HPC clusters specifically designed for large-scale data analysis. The data set will be made available to the scientific community via ORFEUS. By separately providing classical cross-correlation, phase cross-correlation and instantaneous phase stack, the database will offer relative flexibility for application in further studies. Many current

  19. Noise: sound reactive fashion

    OpenAIRE

    Paiva, André; Catarino, André P.; Cabral, Isabel; Carvalho, Helder

    2015-01-01

    Sound and noise have an important influence in our daily lives. They can positively or negatively change our quality of life. Given the idea that it is harder to ignore what we see, rather than what we hear, the team developed a garment that senses environmental noise and shows it through lighting, to make people aware of the noise around them. The garment chosen was a jacket, with a deliberately provocative design. It is the authors’ intention to study the integration of lighting in garments...

  20. Controlled Noise Seismology

    KAUST Repository

    Hanafy, Sherif M.

    2015-08-19

    We use controlled noise seismology (CNS) to generate surface waves, where we continuously record seismic data while generating artificial noise along the profile line. To generate the CNS data we drove a vehicle around the geophone line and continuously recorded the generated noise. The recorded data set is then correlated over different time windows and the correlograms are stacked together to generate the surface waves. The virtual shot gathers reveal surface waves with moveout velocities that closely approximate those from active source shot gathers.

  1. Hypermedicalization in White Noise.

    Science.gov (United States)

    Benson, Josef

    2015-09-01

    The Nazis hijacked Germany's medical establishment and appropriated medical language to hegemonize their ideology. In White Noise, shifting medical information stifles the public into docility. In Nazi Germany the primacy of language and medical authority magnified the importance of academic doctors. The muddling of identities caused complex insecurities and the need for psychological doubles. In White Noise, Professor Gladney is driven by professional insecurities to enact a double in Murray. Through the manipulation of language and medical overreach the U.S., exemplified in the novel White Noise, has become a hypermedicalized society where the spirit of the Hippocratic Oath has eroded. PMID:24458659

  2. Quantum phase slip noise

    Science.gov (United States)

    Semenov, Andrew G.; Zaikin, Andrei D.

    2016-07-01

    Quantum phase slips (QPSs) generate voltage fluctuations in superconducting nanowires. Employing the Keldysh technique and making use of the phase-charge duality arguments, we develop a theory of QPS-induced voltage noise in such nanowires. We demonstrate that quantum tunneling of the magnetic flux quanta across the wire yields quantum shot noise which obeys Poisson statistics and is characterized by a power-law dependence of its spectrum SΩ on the external bias. In long wires, SΩ decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at T →0 . The quantum coherent nature of QPS noise yields nonmonotonous dependence of SΩ on T at small Ω .

  3. Photon shot noise

    OpenAIRE

    Beenakker, C. W. J.; Patra, M.

    1999-01-01

    A recent theory is reviewed for the shot noise of coherent radiation propagating through a random medium. The Fano factor P/I (the ratio of the noise power and the mean transmitted current) is related to the scattering matrix of the medium. This is the optical analogue of Buttiker's formula for electronic shot noise. Scattering by itself has no effect on the Fano factor, which remains equal to 1 (as for a Poisson process). Absorption and amplification both increase the Fano factor above the P...

  4. Noise upon the Sinusoids

    DEFF Research Database (Denmark)

    Jensen, Karl Kristoffer

    2005-01-01

    Sinusoids are used for making harmonic and other sounds. In order to having life in the sounds and adding a wide variety of noises, irregularities are inserted in the frequency and amplitudes. A simple and intuitive noise model is presented, consisting of a low-pass filtered noise, and having...... control for strength and bandwidth. The noise is added on the frequency and amplitudes of the sinusoids, and the resulting irregularity’s (jitter and shimmer) bandwidth is derived. This, together with an overview of investigation methods of the jitter and shimmer results in an analysis of the necessary...... samplerate of the shimmer and jitter. A harmonic model introduces individual and common irregularity, and adds a correlation control. The model has been implemented in max/msp and used in contemporary music compositions....

  5. Noise upon the sinusoids

    DEFF Research Database (Denmark)

    Jensen, Karl Kristoffer

    2005-01-01

    Sinusoids are used for making harmonic and other Sounds. In order to having life in the sounds and adding a wide variety of noises, irregularities are inserted in the frequency and amplitudes. A simple and intuitive noise model is presented, consisting of a low-pass filtered noise, and having...... control for strength and bandwidth. The noise is added on the frequency and amplitudes of the sinusoids, and the resulting irregularity's (jitter and shimmer) bandwidth is derived. This, together with an overview of investigation methods of the jitter and shimmer results in an analysis of the necessary...... samplerate of the shimmer and jitter. A harmonic model introduces individual and common irregularity, and adds a correlation control. The model has been implemented in max/msp and used in contemporary Music compositions....

  6. Conservative Noise Filters

    Directory of Open Access Journals (Sweden)

    Mona M.Jamjoom

    2016-05-01

    Full Text Available Noisy training data have a huge negative impact on machine learning algorithms. Noise-filtering algorithms have been proposed to eliminate such noisy instances. In this work, we empirically show that the most popular noise-filtering algorithms have a large False Positive (FP error rate. In other words, these noise filters mistakenly identify genuine instances as outliers and eliminate them. Therefore, we propose more conservative outlier identification criteria that improve the FP error rate and, thus, the performance of the noise filters. With the new filter, an instance is eliminated if and only if it is misclassified by a mutual decision of Naïve Bayesian (NB classifier and the original filtering criteria being used. The number of genuine instances that are incorrectly eliminated is reduced as a result, thereby improving the classification accuracy.

  7. Geometry And Quantum Noise

    CERN Document Server

    Barbon, Jose L F

    2014-01-01

    We study the fine structure of long-time quantum noise in correlation functions of AdS/CFT systems. Under standard assumptions of quantum chaos for the dynamics and the observables, we estimate the size of exponentially small oscillations and trace them back to geometrical features of the bulk system. The noise level is highly suppressed by the amount of dynamical chaos and the amount of quantum impurity in the states. This implies that, despite their missing on the details of Poincare recurrences, `virtual' thermal AdS phases do control the overall noise amplitude even at high temperatures where the thermal ensemble is dominated by large AdS black holes. We also study EPR correlations and find that, in contrast to the behavior of large correlation peaks, their noise level is the same in TFD states and in more general highly entangled states.

  8. Occupational Noise Exposure

    Science.gov (United States)

    ... the ear drum and are transmitted to the middle and inner ear. In the middle ear three small bones called the malleus (or ... quiet area). Restricting worker presence to a suitable distance away from noisy equipment. Controlling noise exposure through ...

  9. Noise and Neuronal Heterogeneity

    CERN Document Server

    Barber, Michael J

    2010-01-01

    We consider signal transaction in a simple neuronal model featuring intrinsic noise. The presence of noise limits the precision of neural responses and impacts the quality of neural signal transduction. We assess the signal transduction quality in relation to the level of noise, and show it to be maximized by a non-zero level of noise, analogous to the stochastic resonance effect. The quality enhancement occurs for a finite range of stimuli to a single neuron; we show how to construct networks of neurons that extend the range. The range increases more rapidly with network size when we make use of heterogeneous populations of neurons with a variety of thresholds, rather than homogeneous populations of neurons all with the same threshold. The limited precision of neural responses thus can have a direct effect on the optimal network structure, with diverse functional properties of the constituent neurons supporting an economical information processing strategy that reduces the metabolic costs of handling a broad...

  10. TERCEIRO SETOR E MEIO AMBIENTE

    OpenAIRE

    Melo, Marina Félix de

    2012-01-01

    Objetivamos discutir, brevemente, como têm se dado as discussões sobre o Terceiro Setor brasileiro e, particularmente, sobre as ONGs que atuam em defesa do meio ambiente, levantando questionamentos acerca das limitações enfrentadas pelo Terceiro Setor neste contexto

  11. Shape analysis for mobile ambients

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Nielson, Flemming

    2001-01-01

    The ambient calculus is a calculus of computation that allows active processes to move between sites. We present an analysis inspired by state-of-the-art pointer analyses that safely and accurately predicts which processes may turn up at what sites during the execution of a composite system...

  12. Abstract Interpretation of Mobile Ambients

    DEFF Research Database (Denmark)

    Hansen, René Rydhof; Jensen, J. G.; Nielson, Flemming;

    1999-01-01

    We demonstrate that abstract interpretation is useful for analysing calculi of computation such as the ambient calculus (which is based on the p-calculus); more importantly, we show that the entire development can be expressed in a constraint-based formalism that is becoming exceedingly popular...

  13. Shape analysis for Mobile Ambients

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Nielson, Flemming

    2000-01-01

    The ambient calculus is a calculus of computation that allows active processes to move between sites. We present an analysis inspired by state-of-the-art pointer analyses that safety and accurately predicts which processes may turn up at what sites during the execution of a composite system...

  14. La crisis del medio ambiente

    Directory of Open Access Journals (Sweden)

    Juan Carlos Quintero Vélez

    2013-07-01

    Full Text Available Este artículo, introducción al tema del medio ambiente, pretende proporcionar conceptos básicos para analizar y dimensionar el impacto que genera el hombre sobre los sistemas que soportan la vida. Para entender estos problemas, es indispensable partir de un análisis básico de la relación entre el hombre actual, su medio ambiente, sus necesidades y sus actividades. El autor revisa los antecedentes, las causas y las consecuencias de la crisis ambiental internacional, e intenta dar explicación a la problemática nacionalen este campo, y establecer los puntos más críticos en Colombia. Finalmente, con base en los parámetros establecidos por el gobierno, se presenta el concepto de“desarrollo sostenible" como modelo que interrelaciona los procesos económicos, sociales y tecnológicos con el medio ambiente.

  15. Digital identity in ambient environments

    NARCIS (Netherlands)

    Schouten, Ben; Ambekar, Onkar

    2006-01-01

    Embedded systems and ambient technology enable users to interact at any time and anywhere. In the BASIS project for identity management, CWI investigates transparent biometrics in home environments. Possible application areas are user profiling for shopping , listening to one's favourite music and o

  16. Noise Secured Internet

    OpenAIRE

    Barbosa, Geraldo A.

    2005-01-01

    This work shows how a secure Internet can be implemented through a fast key distribution system that uses physical noise to protect the transmitted information. Starting from a shared random sequence $K_0$ between two (or more) users, longsequences $R$ of random bits can be shared. The signals sent over the Internet are deterministic but have a built-in Nature-made uncertainty that protects the shared sequences. After privacy amplification the shared $R$ random bits --encrypted by noise-- are...

  17. Nonequilibrium spin noise spectroscopy

    OpenAIRE

    Li, Fuxiang; Pershin, Yuriy V.; Slipko, Valeriy A.; Sinitsyn, Nikolai A.

    2013-01-01

    Spin Noise Spectroscopy (SNS) is an experimental approach to obtain correlators of mesoscopic spin fluctuations in time by purely optical means. We explore the information that this technique can provide when it is applied to a weakly non-equilibrium regime when an electric current is driven through a sample by an electric field. We find that the noise power spectrum of conducting electrons experiences a shift, which is proportional to the strength of the spin-orbit coupling for electrons mov...

  18. Noise in Biology

    OpenAIRE

    Tsimring, Lev S

    2014-01-01

    Noise permeates biology on all levels, from the most basic molecular, sub-cellular processes to the dynamics of tissues, organs, organisms, and populations. The functional roles of noise in biological processes can vary greatly. Along with standard, entropy-increasing effects of producing random mutations, diversifying phenotypes in isogenic populations, limiting information capacity of signaling relays, it occasionally plays more surprising constructive roles by accelerating the pace of evol...

  19. Gravitational Wave Confusion Noise

    OpenAIRE

    Cornish, Neil J.

    2003-01-01

    One of the greatest challenges facing gravitational wave astronomy in the low frequency band is the confusion noise generated by the vast numbers of unresolved galactic and extra galactic binary systems. Estimates of the binary confusion noise suffer from several sources of astrophysical uncertainty, such as the form of the initial mass function and the star formation rate. There is also considerable uncertainty about what defines the confusion limit. Various ad-hoc rules have been proposed, ...

  20. ENDOGENOUS NOISE TRADERS

    OpenAIRE

    Salomonsson, Marcus

    2006-01-01

    We construct a parsimonious model of a financial market where the marginal investor is an endogenous noise trader. Such a trader anticipates that future shocks may force him to exit his position. In compensation he requires a higher return. We show that the original seller of the asset pays the required return. This can only be optimal if the seller has access to an investment opportunity that gives a sufficiently high return, compared to the noise trader's investment opportunities. We also s...

  1. Noise Stabilized Random Attractor

    OpenAIRE

    Finn, J.M.; Tracy, E. R.; Cooke, W. E.; Richardson, A. S.

    2005-01-01

    A two dimensional flow model is introduced with deterministic behavior consisting of bursts which become successively larger, with longer interburst time intervals between them. The system is symmetric in one variable x and there are bursts on either side of x = 0, separated by the presence of an invariant manifold at x = 0. In the presence of arbitrarily small additive noise in the x direction, the successive bursts have bounded amplitudes and interburst intervals. This system with noise is ...

  2. Active road noise reduction

    OpenAIRE

    Vraničar, Primož

    2012-01-01

    Theoretical principle of noise cancellation can be realized in the ideal studio conditions, but when the experiment is put into actual space and realized, we can see that the sound only partly cancels itself, on some frequencies more and on some less. However, in construction engineering we are not only dealing with certain frequencies but with frequency spectrums, if not with the whole frequency field. It is relatively hard to control the noise in traffic. We are dealing with a larger freque...

  3. Gas plant environmental noise

    International Nuclear Information System (INIS)

    In September 1988, the Energy Resources Conservation Board which regulates the Alberta oil and gas industry tightened its environmental noise guidelines by a factor of 10. New nighttime maximum permissible noise levels as low as 40 dBA are now enforceable in rural areas. The directive is retroactively applicable upon residential complaints and necessitated the use of radical innovations for industry to comply. Details are presented of noise and noise parameters, acoustic fields, dissipation, absorption and diffraction. Major sources of gas plant noise are engine and turbine exhausts, air coolers and cooling towers, purge blowers for electric motors, piping and valves, and flares. Attenuation techniques include silencers, berms and dykes, acoustic lagging and housing, variable speed drives, and stack induced air draft cooler. Recommendations for noise abatement include: house all rotating equipment in acoustically lined buildings; muffle engine exhausts and purge blower vents with reactive silencers where possible; choose electric over engine driven equipment; keep a good mix of engine speeds, fan speeds, and blade counts to reduce tonal spikes; don't rely on berms or dykes; choose water cooling towers over aerial coolers and fit aerial coolers with variable speed drive fans; experiment with stack induced draft coolers where water cooling is not an option; and use process speed valves where possible over bypass valving. 18 figs

  4. Active noise control primer

    CERN Document Server

    Snyder, Scott D

    2000-01-01

    Active noise control - the reduction of noise by generating an acoustic signal that actively interferes with the noise - has become an active area of basic research and engineering applications. The aim of this book is to present all of the basic knowledge one needs for assessing how useful active noise control will be for a given problem and then to provide some guidance for designing, setting up, and tuning an active noise-control system. Written for students who have no prior knowledge of acoustics, signal processing, or noise control but who do have a reasonable grasp of basic physics and mathematics, the book is short and descriptive. It leaves for more advanced texts or research monographs all mathematical details and proofs concerning vibrations, signal processing and the like. The book can thus be used in independent study, in a classroom with laboratories, or in conjunction with a kit for experiment or demonstration. Topics covered include: basic acoustics; human perception and sound; sound intensity...

  5. Noise composed of multiplication of two dichotomous noises

    Institute of Scientific and Technical Information of China (English)

    Li Jing-Hui

    2008-01-01

    In this paper, we introduce a noise which is composed of multiplication of two dichotomous noises, and derive the probability density and the statistical properties of this noise. The obtained results can help study the resonant activation phenomenon, the phenomenon of stochastic resonance, the transport of particles, and the nonequilibrium (phase) transition for the systems driven by this noise.

  6. Aircraft noise - Different ways to monitor the noise load

    Science.gov (United States)

    Bekebrede, G.

    Measures taken by the Dutch government to reduce aircraft-noise disturbances including the establishment of noise zones in which subsequent building is forbidden, while already existing homes are provided with noise insulation are discussed. To ensure accurate noise monitoring, the following recommendations were made by the NLR: (1) regular noise load calculations, utilizing aircraft noise and performance data, the air traffic mix, and flight route information; (2) flight track monitoring, performed by a computerized Flight Track and Aircraft Noise Monitoring System which identifies all aircraft deviating from the prescribed track (i.e., flying over congested regions); and (3) actual noise monitoring, to guard the noise level at a specific noise-sensitive area in close proximity to the airfield, such as a hospital.

  7. Noise Control and Noise Evaluation in Aircraft Engines

    OpenAIRE

    石井, 達哉; Ishii, Tatsuya

    2002-01-01

    Aircraft engine noise emitted for example by the jet exhaust, fan, compressor, turbine and combustor is the predominant factor in total aircraft noise during take-off and landing. As a result of enormous efforts to alleviate engine noise, noise levels have been improved by more than 20 dB compared to the first generation of airliners. However, the growing volume of air transport means that further noise reduction is still required. With this background, we decided to concentrate on two techni...

  8. Reducing environmental noise impacts: A USAREUR noise management program handbook

    Science.gov (United States)

    Feather, Timothy D.; Shekell, Ted K.

    1991-06-01

    Noise pollution is a major environmental problem faced by the U.S. Army in Europe. Noise-related complaints from German citizens can escalate into intense political issues in German communities. This in turn hampers efficient operation of military training and often times threatens the Army's mission. In order to remedy these problems, USAREUR has developed a noise management program. A successful noise management program will limit the impact of unavoidable noise on the populace. This report, a component of the noise management program, is a reference document for noise management planning. It contains guidelines and rules-of-thumb for noise management. This document contains procedures which operation and training level personnel can understand and apply in their day to day noise management planning. Noise mitigation tips are given. Basic technical information that will aid in understanding noise mitigation is provided along with noise management through land use planning. Noise management for specific components of the military community, (airfields, base operations, training areas, and housing and recreation areas) are addressed. The nature of noise generated, means of noise abatement at the source, path, and receiver (both physical and organizational/public relations methods), and a case study example are described.

  9. Historical Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Historical Ambient Air Quality Data Inventory contains measured and estimated data on ambient air pollution for use in assessing air quality, assisting in...

  10. Noise and Function

    CERN Document Server

    Weinstein, Steven

    2016-01-01

    Noise is widely understood to be something that interferes with a signal or process. Thus, it is generally thought to be destructive, obscuring signals and interfering with function. However, early in the 20th century, mechanical engineers found that mechanisms inducing additional vibration in mechanical systems could prevent sticking and hysteresis. This so-called "dither" noise was later introduced in an entirely different context at the advent of digital information transmission and recording in the early 1960s. Ironically, the addition of noise allows one to preserve information that would otherwise be lost when the signal or image is digitized. As we shall see, the benefits of added noise in these contexts are closely related to the phenomenon which has come to be known as stochastic resonance, the original version of which appealed to noise to explain how small periodic fluctuations in the eccentricity of the earth's orbit might be amplified in such a way as to bring about the observed periodic transiti...

  11. Airport noise and teratogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Edmonds, L.D.; Layde, P.M.; Erickson, J.D.

    1979-07-01

    It has been suggested that exposure to high-noise levels near major airports may cause increased incidence of birth defects in the offspring of parents residing near these airports. Using data gathered in Metropolitan Atlanta during 1970 to 1972, we compared the rates of seventeen categories of defects in high- and low-noise census tracts. No significant differences were observed. However, when we subdivided the category of central nervous system defects into several subcategories of specific defects, we noted a significantly increased incidence of spina bifida without hydrocephalus in the high-noise areas. Because of the small number of cases associated with this finding we did a matched case-control study using all cases of central nervous system defects born during the years 1968 to 1976. No significantly increased risk for residents in the high-noise areas was noted in this study. It is our opinion that noise or other factors associated with residence near airports are unlikely to be important environmental teratogens.

  12. Extraaural effects of noise

    Energy Technology Data Exchange (ETDEWEB)

    Marth, E.; Gruber, M.; Koeck, M.; Moese, J.R.; Gallasch, E.; Fueger, G.F.

    This study investigates the effects of a short-term exposition (15 sec) to an indifferent, broad spectrum of noise. Noise levels were set at 85 dB(A) and 110 dB(A). Stress mediators and compensatory mechanisms were studied in 30 test persons. The study was particularly concerned with the metabolic processes providing energy for fight or flight reactions. Most importantly triglycerides are hydrolysed in order to be able to produce the fatty acids that are released. This catabolism is a function of an ACTH-activated lipase. In 93% of the person tested, triglycerides decreased by 7 to 40% of the initial concentration. Blood sugar reaction can be described in two phases: Initially, there was a slight increase in the blood sugar concentration; at higher noise levels, it was followed by a slight decrease. This behaviour was even more characteristic of the insulin concentration. At 85 dB(A), no significant difference concentration was found compared with the levels previous to noise exposition. At 110 dB(A), there was a significant decrease in the insulin level. Vaso constriction of the peripheral blood vessels is a useful parameter for the stress caused by noise. This was shown by registering the finger pulse during the test.

  13. Structural lubricity under ambient conditions

    Science.gov (United States)

    Cihan, Ebru; İpek, Semran; Durgun, Engin; Baykara, Mehmet Z.

    2016-01-01

    Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (∼4,000–130,000 nm2) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold–graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro- and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions. PMID:27350035

  14. Fiscalidad ambiental (curso 2011-2012)

    OpenAIRE

    Gil Maciá, Lorenzo

    2012-01-01

    Tema fiscalidad ambiental. 1. Necesidad económica y jurídica de la protección del medio ambiente. 2. Características, naturaleza y clasificación de los tributos ambientales. 3. Competencias tributarias en el ámbito estatal, autonómico y local. 4. La fiscalidad ambiental en la legislación fiscal española. 5. Perspectivas de futuro en materia de imposición ambiental.

  15. Traffic noise and cardiovascular disease

    OpenAIRE

    Selander, Jenny

    2010-01-01

    Traffic noise is an increasing problem in urban areas worldwide, but health effects in relation to traffic noise exposure are not well understood. Several studies show that noise may give rise to acute stress reactions, possibly leading to cardiovascular effects, but the evidence is limited on cardiovascular risks associated with traffic noise exposure. Cardiovascular effects have been indicated for other environmental stressors such as occupational noise exposure and job ...

  16. Monitoring of Noise During Ganeshotsav

    OpenAIRE

    Mrs. P. Saler; Mr. Satyasheel Vibhute

    2011-01-01

    Sound is a form of energy emitted by a vibrating body causing change in pressure of the surrounding elastic medium through which energy is transmitted. Noise has been defined as unwanted sound. Noise is a disturbance to the human environment which is escalating at a high rate. There are numerous effects of noise on human and environment due to the increase in noise pollution slowly, insensibly; we seem to accept noise and the physiological and psychological deterioration that accompanies it a...

  17. Lower Hearing Threshold by Noise

    Institute of Scientific and Technical Information of China (English)

    龙长才; 邵峰; 张燕萍; 秦佑国

    2004-01-01

    We demonstrate that noise can be a benefit factor that enables us to hear weaker signals. We measured the hearing thresholds of subjects for pure tone in different noise levels. The results show that pure tone thresholds with noise of some levels are lower than that without noise. The largest down-shift of the threshold by noise among the examined subjects is 5. 7dB, and the smallest is 1.7dB.

  18. Hypermedia in the Ambient Wood

    OpenAIRE

    Weal, Mark J; Michaelides, Danius T.; Thompson, Mark K.; De Roure, David C

    2003-01-01

    The Ambient Wood project, carried out as part of the Equator IRC, set out to provide an augmented learning experience for children in an outdoor environment. Using a variety of devices, the children gathered information about the woodland habitats performing basic scientific enquiry and hypothesis testing. In this paper we describe the supporting information infrastructure used in the project, focusing on how hypermedia tools and techniques were used to structure and deliver the information t...

  19. Crumpling under an ambient pressure

    OpenAIRE

    Lin, Y C; Wang, Y. L.; Liu, Y; Hong, T.M.

    2008-01-01

    A pressure chamber is designed to study the crumpling process under an ambient force. The compression force and its resulting radius for the ball obey a power law with an exponent that is independent of the thickness and initial size of the sheet. However, the exponent is found to be material-dependent and less than the universal value, 0.25, claimed by the previous simulations. The power law behavior disappears at high pressure when the compressibility drops discontinuously, which is suggest...

  20. 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.

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

    Science.gov (United States)

    Dziak, Robert P; Bohnenstiehl, DelWayne R; Stafford, Kathleen M; Matsumoto, Haruyoshi; Park, Minkyu; Lee, Won Sang; Fowler, Matt J; Lau, Tai-Kwan; Haxel, Joseph H; Mellinger, David K

    2015-01-01

    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. PMID:25875205

  2. 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.

  3. Estrategia para la sustentabilidad ambiental

    Directory of Open Access Journals (Sweden)

    Cecilia Erbiti

    2006-01-01

    Full Text Available En el contexto de los postulados conceptuales y metodológicos de la planificación estratégica y de sustentabilidad ambiental, el objetivo de esta investigación es describir el proceso de formulación del Plan de Ordenamiento Territorial del Municipio de Tandil (POTM y analizar su potencialidad para avanzar hacia la sustentabilidad ambiental del sistema. Los resultados de la misma muestran que el POTM no sólo prioriza principios, objetivos y estrategias que materializan las diferentes manifestaciones de la sustentabilidad (económica, social, ecológica y política, sino que la totalidad del Plan se fundamenta en el concepto de desarrollo sostenible y, con ello, se establecen prioridades de actuación que posibilitarán la gestión ambiental urbana. Si bien el POTM muestra una gran potencialidad para avanzar hacia la sustentabilidad del territorio, la implementación y cumplimiento del mismo constituye un fuerte desafío para las autoridades de aplicación.

  4. 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

  5. Ambient Vibration Test on Reinforced Concrete Bridges

    Directory of Open Access Journals (Sweden)

    Idris Nurul Shazwin

    2016-01-01

    Full Text Available An investigation was carried out to determine dynamic characteristic of reinforced concrete (RC bridges by using ambient vibration test (AVT. The ambient vibration sources on bridges may come from traffic, wind, wave motion and seismic events. AVT describes the dynamic characteristics of the bridge and ground by measuring the natural frequencies using highly sensitive seismometer sensor. This test is beneficial due to light weight equipment and smaller number of operator required, cheap and easy to be handled. It is able to give a true picture of the bridge dynamic behavior without any artificial force excitation when vibration data is recorded. A three-span reinforced concrete bridge located in Sri Medan, Batu Pahat, Johor was measured by using microtremor equipment consist of three units of 1 Hz eigenfrequency passive sensors used in this test was performed in normal operating condition without excitation required from any active sources or short period noise perturbations. Ten measurements were conducted on the bridge deck and ten measurements on the ground surface in order to identify the natural frequencies of the bridge. Several peak frequencies were identified from three components of Fourier Amplitude Spectra (FAS in transverse (North-South, longitudinal (East-West and vertical (Up-Down direction as well as squared average Horizontal to Vertical Spectral Ratio (HVSR of ground response, computed by using Geopsy software. From the result, it was expected the bridge have five vibration modes frequencies in the range of 1.0 Hz and 7.0 Hz with the first two modes in the transverse and longitudinal direction having a frequency 1.0 Hz, the third mode is 2.2 Hz in transverse direction, fourth and fifth mode is 5.8 Hz and 7.0 Hz. For ground natural frequencies are in range 1.0 Hz to 1.3 Hz for North-South direction and 1.0 Hz to 1.6 Hz for East-West direction. Finally the results are compared with several empirical formulas for simple

  6. ECG De-noising

    DEFF Research Database (Denmark)

    Kærgaard, Kevin; Jensen, Søren Hjøllund; Puthusserypady, Sadasivan

    2015-01-01

    Electrocardiogram (ECG) is a widely used noninvasive method to study the rhythmic activity of the heart and thereby to detect the abnormalities. However, these signals are often obscured by artifacts from various sources and minimization of these artifacts are of paramount important. This paper...... proposes two adaptive techniques, namely the EEMD-BLMS (Ensemble Empirical Mode Decomposition in conjunction with the Block Least Mean Square algorithm) and DWT-NN (Discrete Wavelet Transform followed by Neural Network) methods in minimizing the artifacts from recorded ECG signals, and compares...... their performance. These methods were first compared on two types of simulated noise corrupted ECG signals: Type-I (desired ECG+noise frequencies outside the ECG frequency band) and Type-II (ECG+noise frequencies both inside and outside the ECG frequency band). Subsequently, they were tested on real ECG recordings...

  7. Road Traffic Noise

    Science.gov (United States)

    Beckenbauer, Thomas

    Road traffic is the most interfering noise source in developed countries. According to a publication of the European Union (EU) at the end of the twentieth century [1], about 40% of the population in 15 EU member states is exposed to road traffic noise at mean levels exceeding 55 dB(A). Nearly 80 million people, 20% of the population, are exposed to levels exceeding 65 dB(A) during daytime and more than 30% of the population is exposed to levels exceeding 55 dB(A) during night time. Such high noise levels cause health risks and social disorders (aggressiveness, protest, and helplessness), interference of communication and disturbance of sleep; the long- and short-term consequences cause adverse cardiovascular effects, detrimental hormonal responses (stress hormones), and possible disturbance of the human metabolism (nutrition) and the immune system. Even performance at work and school could be impaired.

  8. Shot Noise in Graphene

    OpenAIRE

    DiCarlo, L.; Williams, J.R.; Zhang, Yiming; McClure, D. T.; Marcus, C. M.

    2007-01-01

    We report measurements of current noise in single- and multi-layer graphene devices. In four single-layer devices, including a p-n junction, the Fano factor remains constant to within +/-10% upon varying carrier type and density, and averages between 0.35 and 0.38. The Fano factor in a multi-layer device is found to decrease from a maximal value of 0.33 at the charge-neutrality point to 0.25 at high carrier density. These results are compared to theoretical predictions for shot noise in balli...

  9. Community response to noise

    Directory of Open Access Journals (Sweden)

    Takashi Yano

    2012-01-01

    Full Text Available Activities from 2008 to 2011 by ICBEN community response to noise team were summarized. That is, individual community-based indexes such as community tolerance Level, Zuricher Fluglarm Index (ZFI and Frankfurter Fluglarm Index (FFI/FNI were newly proposed, differences in railway bonus between Europe and Asia were discussed by a Swedish survey, socio-acoustic surveys were reported from developing countries, and annoyance equivalents and dominant source models were proposed as the adequate combined noise model. Furthermore, not only negative, but also positive aspects of sound were discussed as soundscape studies. Finally, seven items were listed as future team activities.

  10. Noise Source Location Optimization

    Directory of Open Access Journals (Sweden)

    Ed O’Keefe

    1994-01-01

    Full Text Available This article describes a method to determine locations of noise sources that minimize modal coupling in complex acoustic volumes. Using the acoustic source scattering capabilities of the boundary element method, predictions are made of mode shape and pressure levels due to various source locations. Combining knowledge of the pressure field with a multivariable function minimization technique, the source location generating minimum pressure levels can be determined. The analysis also allows for an objective comparison of “best/worst” locations. The technique was implemented on a personal computer for the U.S. Space Station, predicting 5–10 dB noise reduction using optimum source locations.

  11. Noise detection during heart sound recording using periodicity signatures

    International Nuclear Information System (INIS)

    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

  12. Phase-Sensitive Noise Suppression in a Photoacoustic Sensor based on Acoustic Circular Membrane Modes

    CERN Document Server

    Lassen, Mikael; Balslev-Harder, David; Petersen, Jan C

    2014-01-01

    A photoacoustic (PA) sensor based on higher order acoustic modes is demonstrated. The PA sensor is designed to enhance the gas-detection performance and simultaneously suppress ambient noise sources (e.g. flow noise, electrical noise and external acoustic noise). Two microphones are used and positioned such that the PA signals are ($\\pi$) out of phase. Ambient acoustic noise are approximately in the same phase and will be subtracted and thus improve the SNR. In addition, by placing the gas in- and outlets so that the gas flows through the node of the first higher order membrane mode the coupling of flow noise is approximately 20 dB lower compared with flow through the fundamental mode at 5 L/min. The noise reduction and thus the increase in sensitivity is demonstrated by measuring vibrational lines of methanol and methane using a broadband interband cascade laser emitting radiation at 3.38 $\\mu$m. A signal-to-noise improvement of 20 (26 dB) using higher order modes are demonstrated compared with the fundament...

  13. Experimental Characterization of Wind Turbine Blade Aerodynamic Noise

    Science.gov (United States)

    Ingemanson, Megan Lynn

    Wind turbine noise at low frequencies less than 300Hz is not only annoying to humans but has been proven to cause serious health issues. Additionally, animals are severely affected by wind turbines because a small increase in ambient noise (as is produced by wind turbines) significantly reduces their listening ability. In an attempt to better understand and characterize the aerodynamic noise of wind turbine blades, experimental testing was completed on PowerWorks 100kW and GudCraft WG700 blade specimens in the University of California, Davis Transportation Noise Control Center's anechoic chamber. Experimental testing and data analysis proved approximately 4.0dB to 6.0dB was produced due to the blades' geometric design for both blade specimens at low frequencies. This noise was maximized at the blades' leading edge along the central portion of the blades' radius. Theoretical prediction models have been used to determine that, for typical wind speeds and low frequencies, noise generated due to the tip passing frequency is clearly predominant.

  14. How to Evaluate the Electric Noise in a Cell Membrane?

    Science.gov (United States)

    Bier, M.

    2006-05-01

    There has been considerable public anxiety about possible health effects of electromagnetic radiation emitted by high voltage power lines. Power frequencies (60 Hz in the US, 50 Hz in many other countries) are sufficiently slow for the associated electric fields to distribute themselves across the highly resistive cell membranes. To assess the ambient power frequency fields, researchers have compared the voltage that these fields induce across cell membranes to the strength of the electric noise that the membranes generate themselves through Brownian motion. However, there has been disagreement among researchers on how to evaluate this equilibrium membrane electric noise. I will review the different approaches and present an {ITALIC ab initio} modeling of membrane electric fields. I will show that different manifestations of Brownian noise lead to an electric noise intensity that is many times larger than what conventional estimates have yielded. Next, the legitimacy of gauging a nonequilibrium external signal against internal equilibrium noise is questioned and a more meaningful criterion is proposed. Finally, an estimate will be derived of the nonequilibrium noise intensity due to the driven ion traffic through randomly opening and closing ion channels.

  15. Noise sources and noise suppression in CMOS imagers

    Science.gov (United States)

    Pain, Bedabrata; Cunningham, Thomas J.; Hancock, Bruce R.

    2004-01-01

    Mechanisms for noise coupling in CMOS imagers are complex, since unlike a CCD, a CMOS imager has to be considered as a full digital-system-on-a-chip, with a highly sensitive front-end. In this paper, we analyze the noise sources in a photodiode CMOS imager, and model their propagation through the signal chain to determine the nature and magnitude of noise coupling. We present methods for reduction of noise, and present measured data to show their viability. For temporal read noise reduction, we present pixel signal chain design techniques to achieve near 2 electrons read noise. We model the front-end reset noise both for conventional photodiode and CTIA type of pixels. For the suppression of reset noise, we present a column feedback-reset method to reduce reset noise below 6 electrons. For spatial noise reduction, we present the design of column signal chain that suppresses both spatial noise and power supply coupling noise. We conclude by identifying problems in low-noise design caused by dark current spatial distribution.

  16. Nonlinear Elasticity in a Deforming Ambient Space

    Science.gov (United States)

    Yavari, Arash; Ozakin, Arkadas; Sadik, Souhayl

    2016-07-01

    In this paper, we formulate a nonlinear elasticity theory in which the ambient space is evolving. For a continuum moving in an evolving ambient space, we model time dependency of the metric by a time-dependent embedding of the ambient space in a larger manifold with a fixed background metric. We derive both the tangential and the normal governing equations. We then reduce the standard energy balance written in the larger ambient space to that in the evolving ambient space. We consider quasi-static deformations of the ambient space and show that a quasi-static deformation of the ambient space results in stresses, in general. We linearize the nonlinear theory about a reference motion and show that variation of the spatial metric corresponds to an effective field of body forces.

  17. Spin Hall noise

    NARCIS (Netherlands)

    Kamra, A.; Witek, F.P.; Meyer, S.; Huebl, H.; Geprägs, S.; Gross, R.; Bauer, G.E.W.; Goennenwein, S.T.B.

    2014-01-01

    We measure the low-frequency thermal fluctuations of pure spin current in a platinum film deposited on yttrium iron garnet via the inverse spin Hall effect (ISHE)-mediated voltage noise as a function of the angle α between the magnetization and the transport direction. The results are consistent wit

  18. Exploring Noise: Sound Pollution.

    Science.gov (United States)

    Rillo, Thomas J.

    1979-01-01

    Part one of a three-part series about noise pollution and its effects on humans. This section presents the background information for teachers who are preparing a unit on sound. The next issues will offer learning activities for measuring the effects of sound and some references. (SA)

  19. Low-noise gallium-arsenide field-effect transistor preamplifiers for stochastic beam-cooling systems

    International Nuclear Information System (INIS)

    The present noise performance, bandwidth capability and gain stability of bipolar and field-effect transistors, parametric amplifier, Schottky diode mixer and maser are summarized and compared in the 100 MHz to 40 GHz frequency range for stochastic beam cooling systems. Stability factor of GaAs FET's as a function of ambient temperature is presented and discussed. Performance data of several low-noise wide-band cryogenically cooled preamplifiers are presented including one with a noise figure of 0.35 dB over a bandwidth range of 150 to 500 MHz operating at ambient temperature of 200K. Also, data are given on a broadband 1 to 2 GHz preamplifier having a noise figure of approximately 0.2 dB. The gain, operating noise temperature, stability, gain nonuniformity and phase-shift as function of frequency of interest for beam cooling systems are discussed

  20. Hidrogeología ambiental

    OpenAIRE

    Auge, Miguel

    2004-01-01

    La finalidad de este libro es introducir a aquellos que trabajan en agua subterránea, en una temática relativamente moderna pero que en los últimos 15 a 20 años, ha concentrado la mayor demanda laboral de geólogos en los países desarrollados del Hemisferio Norte. En el tomo I se analiza la relación del agua subterránea con el ambiente, tratando especialmente, el origen, las características, y los procesos de contaminación. Se describe la relación agua superficial-subterránea y su incidencia e...

  1. Pediatria ambiental: um tema emergente

    Directory of Open Access Journals (Sweden)

    Patricia M. Valenzuela

    2011-04-01

    Full Text Available OBJETIVO: Revisar os artigos mais relevantes sobre a pediatria ambiental, seus efeitos potenciais para a saúde e, especialmente, seus avanços na prevenção. FONTES DOS DADOS: Foi realizada uma pesquisa utilizando as bases de dados MEDLINE/PubMed e SciELO. Foram revisados artigos de 1990 a 2010, além de capítulos de livros relacionados à pediatria ambiental. SÍNTESE DOS DADOS: Há uma variedade significativa de fatores que tornam as crianças altamente vulneráveis à exposição a riscos ambientais, associados principalmente ao consumo comparativamente maior de água, comida e ar por parte da criança, em relação ao seu peso corporal. De acordo com a Organização Mundial de Saúde, mais de 3 milhões de crianças menores de 5 anos morrem devido a doenças relacionadas ao meio ambiente. Aproximadamente 30-40% das doenças pediátricas estão relacionadas a fatores ambientais. As crianças estão constantemente expostas a vários riscos ambientais para a saúde, dentre os quais se destacam: água contaminada, falta de condições adequadas de saneamento, poluição do ar, vetores de doenças, perigos químicos, injúrias e acidentes. CONCLUSÕES: Atualmente, os pediatras são desafiados a tratar das necessidades de saúde ligadas à pediatria ambiental. A história pediátrica deve ser mais abrangente, acrescentando-se questões pontuais que ajudem a identificar potenciais riscos ambientais. A conscientização e o entendimento sobre os efeitos nocivos das várias condições ambientais e o conhecimento sobre as medidas de prevenção relacionadas resultarão em intervenções oportunas e adequadas que melhorarão a saúde e o desenvolvimento das nossas crianças.

  2. Responsabilidades municipales en materia ambiental

    OpenAIRE

    Ignacio Pichardo Pagaza

    2009-01-01

    Los municipios tienen una responsabilidad directa, inmediata e ineludible hacia el medio ambiente que hasta hace pocos años no reconocían como pri mor dial sino como una función secundaria. Hoy es más que una obligación jurídica, es un compromiso so cial del nivel de gobierno más cercano a la sociedad. Este trabajo reflexiona en torno a las responsabilidades que la Constitución política impone de manera exclusiva a los municipios y que por su naturaleza tienen efectos directos en el medio amb...

  3. Noise synthesis for the Virtual Community Noise Simulator

    OpenAIRE

    Arntzen, M.

    2013-01-01

    Aircraft noise imposes restrictions on possible growth of airports. Noise mitigation measures can be based long-term predictive models but would benefit from high-fidelity simulation of the audible effects. To this end the NLR uses its Virtual Community Noise Simulator (VCNS). Several modelling steps and an application will be demonstrated in this article as to show the promising future of aircraft noise synthesis.

  4. 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...

  5. Annoyance of low frequency noise and traffic noise

    DEFF Research Database (Denmark)

    Mortensen, Frank Rysgaard; Poulsen, Torben

    2000-01-01

    The annoyance of different low frequency noise sources was determined and compared to the annoyance from traffic noise. Twenty-two test 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...

  6. 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,

  7. The Traffic Noise Index: A Method of Controlling Noise Nuisance.

    Science.gov (United States)

    Langdon, F. J.; Scholes, W. E.

    This building research survey is an analysis of the social nuisance caused by urban motor ways and their noise. The Traffic Noise Index is used to indicate traffic noises and their effects on architectural designs and planning, while suggesting the need for more and better window insulation and acoustical barriers. Overall concern is for--(1)…

  8. 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 harmfu

  9. Noise-Induced Hearing Loss

    Science.gov (United States)

    ... Home » Health Info » Hearing, Ear Infections, and Deafness Noise-Induced Hearing Loss On this page: What is ... I find additional information about NIHL? What is noise-induced hearing loss? Every day, we experience sound ...

  10. Fast High-Quality Noise

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Wyvill, Geoff

    2007-01-01

    At the moment the noise functions available in a graphics programmer's toolbox are either slow to compute or they involve grid-line artifacts making them of lower quality. In this paper we present a real-time noise computation with no grid-line artifacts or other regularity problems. In other words......, we put a new tool in the box that computes fast high-quality noise. In addition to being free of artifacts, the noise we present does not rely on tabulated data (everything is computed on the fly) and it is easy to adjust quality vs. quantity for the noise. The noise is based on point rendering (like...... spot noise), but it extends to more than two dimensions. The fact that it is based on point rendering makes art direction of the noise much easier....

  11. Cancellation technique of external noise inside a magnetically shielded room used for biomagnetic measurements

    Science.gov (United States)

    Kandori, Akihiko; Miyashita, Tsuyoshi; Tsukada, Keiji

    2000-05-01

    First-order gradiometers inside a magnetically shielded room (MSR) were used to cancel magnetic-field noise. However, the magnetic field inside a MSR is distorted when the amount of external noise is large. This distortion is caused by the low-pass filter property of the MSR. Therefore, the time constants of the frequency-dependent attenuation of the MSR vary spatially and this variation must be taken into account. To investigate noise cancellation, we used a multichannel superconducting quantum interference device consisting of four gradiometers measuring a source signal and two gradiometers as a reference. To compensate for the different magnitudes of the gradiometer wave forms, which differed because of slight differences in their pickup-coil cancel rates, we calculated a fitting parameter. The noise-cancellation method consisted of two processes: reduction of ambient noise caused by the differences in the cancel rate of the gradiometers and a gradient magnetic field inside the MSR, and cancellation of wave-form distortion caused by the spatial variation of the time constants inside the MSR. This cancellation method provides additional attenuation of over 20-30 dB in addition to the balance (>46 dB) of a first-order gradiometer. However, the remaining noise, especially a spike (<2 pT) at the beginning of a large ambient noise step, could not be completely canceled. This noise was caused by the slight difference between the time constants at the reference sensor position and at the signal sensor position. Except for this noise spike, however, the noise cancellation enabled clear magnetocardiogram wave forms to be measured without being affected by strong external noise.

  12. 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.

  13. How CANMET tests noise pollution

    Energy Technology Data Exchange (ETDEWEB)

    Savich, M.U.

    1983-07-01

    The paper describes a noise control program that CANMET has developed to protect miners from permanent hearing loss. Studies at a uranium mine at Elliot Lake were used to reach three objectives: first to identify main underground job categories by noise exposure index; second to measure cyclical noise; and third to establish the effectiveness of ear muffs used in mines. Some of the data obtained is included. Several recommendations for noise control are made.

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

    OpenAIRE

    Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie; Ekström, Göran; Zunino, Andrea; Giardini, Domenico

    2013-01-01

    International audience 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 method involves the time-domain cross-correlation of signal recorded at different stations; the other is based on frequency-domain cross-correlation, and requires finding the ze...

  15. 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.

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

    Science.gov (United States)

    Salomons, Erik M; Janssen, Sabine A

    2011-06-01

    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 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. PMID:21776205

  17. Low-frequency noise complaints

    DEFF Research Database (Denmark)

    Pedersen, Christian Sejer; Møller, Henrik; Persson-Waye, Kerstin

    2006-01-01

    In Denmark and in other industrialized countries there are cases where people complain about annoying low-frequency or infrasonic noise in their homes. Besides noise annoyance people often report other adverse effects such as insomnia, headache, lack of concentration etc. In many cases the noise...

  18. 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 noi

  19. Weak localization of photon noise

    NARCIS (Netherlands)

    Scalia, Paolo S.; Muskens, Otto L.; Lagendijk, Ad

    2013-01-01

    We present an experimental study of coherent backscattering (CBS) of photon noise from multiple scattering media. We use a pseudothermal light source with a microsecond coherence time to produce a noise spectrum covering a continuous transition, from wave fluctuations to shot noise over several MHz.

  20. Ex / Noise / CERN / Deerhoof

    CERN Multimedia

    CERN, SM18,

    2015-01-01

    Indie rockers Deerhoof battled with the noise of CERN’s magnet test facilities on 30 August 2015. The band visited CERN at the invitation of ATLAS physicist James Beacham, whose pilot project Ex/Noise/CERN collides experimental music artists with experimental particle physics. Credits: -Producer- CERN Video Productions James Beacham François Briard -Director- Noemi Caraban -Camera- Yann Krajewski Piotr Traczyk Noemi Caraban -Crane operator- Antonio Henrique Jorge-Costa -Live recording at CERN- Mixing at Rec studio/Geneva By Serge Morattel -Infography- Daniel Dominguez Noemi Caraban -Deerhoof- John Dieterich Satomi Matsuzaki Ed Rodriguez Greg Saunier w/Deron Pulley SPECIAL THANKS TO: Michal Strychalski Marta Bajko Maryline Charrondiere Luca Bottura Christian Giloux Rodrigue Faes Mariane Catallon Georgina Hobgen Hailey Reissman Marine Bass

  1. The IDC Seismic, Hydroacoustic and Infrasound Global Low and High Noise Models

    Science.gov (United States)

    Brown, David; Ceranna, Lars; Prior, Mark; Mialle, Pierrick; Le Bras, Ronan J.

    2014-03-01

    The International Data Centre (IDC) in Vienna, Austria, is determining, as part of automatic processing, sensor noise levels for all seismic, hydroacoustic, and infrasound (SHI) stations in the International Monitoring System (IMS) operated by the Provisional Technical Secretariat of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). Sensor noise is being determined several times per day as a power spectral density (PSD) using the Welch overlapping method. Based on accumulated PSD statistics a probability density function (PDF) is also determined, from which low and high noise curves for each sensor are extracted. Global low and high noise curves as a function of frequency for each of the SHI technologies are determined as the minimum and maximum of the individual station low and high noise curves, respectively, taken over the entire network of contributing stations. An attempt is made to ensure that only correctly calibrated station data contributes to the global noise models by additionally considering various automatic detection statistics. In this paper global low and high noise curves for 2010 are presented for each of the SHI monitoring technologies. Except for a very slight deviation at the microseism peak, the seismic global low noise model returns identically the Peterson (1993) NLNM low noise curve. The global infrasonic low noise model is found to agree with that of Bowman et al. (2005, 2007) but disagrees with the revised results presented in Bowman et al. (2009) by a factor of 2 in the calculation of the PSD. The global hydroacoustic low and high noise curves are found to be in quantitative agreement with Urick's oceanic ambient noise curves for light to heavy shipping. Whale noise is found to be a feature of the hydroacoustic high noise curves at around 15 and 25 Hz.

  2. Noise characterization for LISA

    OpenAIRE

    Sylvestre, Julien; Tinto, Massimo

    2003-01-01

    We consider the general problem of estimating the inflight LISA noise power spectra and cross-spectra, which are needed for detecting and estimating the gravitational wave signals present in the LISA data. For the LISA baseline design and in the long wavelength limit, we bound the error on all spectrum estimators that rely on the use of the fully symmetric Sagnac combination ($\\zeta$). This procedure avoids biases in the estimation that would otherwise be introduced by the presence of a stron...

  3. Probabilistic noise reduction

    OpenAIRE

    Hansen, James A.; Smith, Leonard A

    2011-01-01

    State estimation is an important factor in the production of accurate forecasts. Great effort isexpended in reducing the noise inherent in observations, to produce a ‘‘best’’ estimate of thetrue system state. But noisy observations necessitate a probabilistic, not a deterministic,approach to state estimation. A state’s probabilistic description is rarely Gaussian, and requiresinformation beyond variance magnitude; the correct distribution is restricted by the underlyingstructure of the system...

  4. Stochastic noise in translation

    OpenAIRE

    Stefaniuk, Adam; Racle, Julien; Hatzimanikatis, Vassily

    2011-01-01

    Translation lies at the heart of every living organism, it is the process synthesizing the proteins, a main component in the cells. Earlier studies have considered protein synthesis as mainly initiation limited, modeling it as a first-order reaction with respect to free ribosomes and mRNA. In such studies, the noise is therefore coming from initiation phase only. We have previously studied a continuous deterministic model for translation, taking into account the ribosome elongation and a poss...

  5. Sonic Crystal Noise Barriers

    OpenAIRE

    Chong, Yung

    2012-01-01

    An alternative road traffic noise barrier using an array of periodically arranged vertical cylinders known as a Sonic Crystal (SC) is investigated. As a result of multiple (Bragg) scattering, SCs exhibit a selective sound attenuation in frequency bands called band gaps or stop bands related to the spacing and size of the cylinders. Theoretical studies using Plane Wave Expansion (PWE), Multiple Scattering Theory (MST) and Finite Element Method (FEM) have enabled study of the performance of SC ...

  6. Dynamical decoupling noise spectroscopy

    OpenAIRE

    Alvarez, Gonzalo A.; Suter, Dieter

    2011-01-01

    Decoherence is one of the most important obstacles that must be overcome in quantum information processing. It depends on the qubit-environment coupling strength, but also on the spectral composition of the noise generated by the environment. If the spectral density is known, fighting the effect of decoherence can be made more effective. Applying sequences of inversion pulses to the qubit system, we generate effective filter functions that probe the environmental spectral density. Comparing d...

  7. Noise induced Hopf bifurcation

    OpenAIRE

    Shuda, I. A.; Borysov, S S; A.I. Olemskoi

    2008-01-01

    We consider effect of stochastic sources upon self-organization process being initiated with creation of the limit cycle induced by the Hopf bifurcation. General relations obtained are applied to the stochastic Lorenz system to show that departure from equilibrium steady state can destroy the limit cycle in dependence of relation between characteristic scales of temporal variation of principle variables. Noise induced resonance related to the limit cycle is found to appear if the fastest vari...

  8. Higher moments of noise

    OpenAIRE

    Reulet, Bertrand

    2005-01-01

    In this article we present simple approaches to the calculation of P(i) (the probability distribution of current fluctuations) in a tunnel junction, and to the effect of the environment on noise measurements in terms of the modification of P. We do not provide rigorous calculations, but simple considerations that bear the essential ingredients of the phenomena. We also discuss the effect of a finite measurement bandwidth. We report experimental results of the first measurement of the third mo...

  9. Thermal noise engines

    OpenAIRE

    Kish, Laszlo B.

    2010-01-01

    Electrical heat engines driven by the Johnson-Nyquist noise of resistors are introduced. They utilize Coulomb's law and the fluctuation-dissipation theorem of statistical physics that is the reverse phenomenon of heat dissipation in a resistor. No steams, gases, liquids, photons, combustion, phase transition, or exhaust/pollution are present here. In these engines, instead of heat reservoirs, cylinders, pistons and valves, resistors, capacitors and switches are the building elements. For the ...

  10. Noise Phobia in Dog

    Directory of Open Access Journals (Sweden)

    Mangle

    Full Text Available Fear of thunderstorms and other forms of noise phobia are common problems in dogs. Administering medications along with changing the pet’s environment, and using behavior modification techniques can help ease the fear. Above all, do not give your pet any attention or reward when he is showing signs of fear; this will only reinforce the fearful behavior. [Veterinary World 2008; 1(11.000: 351-352

  11. Spin Hall noise

    OpenAIRE

    Kamra, A.; Witek, F.P.; Meyer, S.; Huebl, H.; Geprägs, S.; Gross, R.; Bauer, G. E. W.; Goennenwein, S. T. B.

    2014-01-01

    We measure the low-frequency thermal fluctuations of pure spin current in a Platinum film deposited on yttrium iron garnet via the inverse spin Hall effect (ISHE)-mediated voltage noise as a function of the angle $\\alpha$ between the magnetization and the transport direction. The results are consistent with the fluctuation dissipation theorem in terms of the recently discovered spin Hall magnetoresistance (SMR). We present a microscopic description of the $\\alpha$ dependence of the voltage no...

  12. Community response to noise

    OpenAIRE

    Takashi Yano; Truls Gjestland; Soogab Lee

    2012-01-01

    Activities from 2008 to 2011 by ICBEN community response to noise team were summarized. That is, individual community-based indexes such as community tolerance Level, Zuricher Fluglarm Index (ZFI) and Frankfurter Fluglarm Index (FFI/FNI) were newly proposed, differences in railway bonus between Europe and Asia were discussed by a Swedish survey, socio-acoustic surveys were reported from developing countries, and annoyance equivalents and dominant source models were proposed as the adequate co...

  13. PeaceKeeper: Augmenting the Awareness and Communication of Noise Pollution in Student Dormitories

    DEFF Research Database (Denmark)

    Lanng, Henrik; Lykkegaard,, Anders; Thornholm, Søren;

    . To address this challenge, we explore how to augment the awareness and communication of environmental noise among dorm residents through an ambient awareness system: PeaceKeeper. We describe the initial design, implementation and concept validation of PeaceKeeper with two students living in contiguous rooms...

  14. Road traffic noise and incident myocardial infarction: a prospective cohort study

    NARCIS (Netherlands)

    Sørensen, M.; Andersen, Z.J.; Nordsborg, R.B.; Jensen, S.; Lillelund, K.G.; Beelen, R.M.J.; Schmidt, E.B.; Tjønneland, A.; Overvad, K.; Raaschou-Nielsen, O.

    2012-01-01

    BACKGROUND 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. METHODS In a population-based cohort of 57 053 people aged 50 to 64 years at enrolment in 1993-1997, we identified 1600 ca

  15. Aircraft noise prediction

    Science.gov (United States)

    Filippone, Antonio

    2014-07-01

    This contribution addresses the state-of-the-art in the field of aircraft noise prediction, simulation and minimisation. The point of view taken in this context is that of comprehensive models that couple the various aircraft systems with the acoustic sources, the propagation and the flight trajectories. After an exhaustive review of the present predictive technologies in the relevant fields (airframe, propulsion, propagation, aircraft operations, trajectory optimisation), the paper addresses items for further research and development. Examples are shown for several airplanes, including the Airbus A319-100 (CFM engines), the Bombardier Dash8-Q400 (PW150 engines, Dowty R408 propellers) and the Boeing B737-800 (CFM engines). Predictions are done with the flight mechanics code FLIGHT. The transfer function between flight mechanics and the noise prediction is discussed in some details, along with the numerical procedures for validation and verification. Some code-to-code comparisons are shown. It is contended that the field of aircraft noise prediction has not yet reached a sufficient level of maturity. In particular, some parametric effects cannot be investigated, issues of accuracy are not currently addressed, and validation standards are still lacking.

  16. Turbine airfoil with ambient cooling system

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Predicateμ-Calculus for Mobile Ambients

    Institute of Scientific and Technical Information of China (English)

    Hui-Min Lin

    2005-01-01

    Ambient logics have been proposed to describe properties for mobile agents which may evolve over time as well as space. This paper takes a predicate-based approach to extending an ambient logic with recursion, yielding a predicate t-calculus in which fixpoint formulas are formed using predicate variables. An algorithm is developed for model checking finite-control mobile ambients against formulas of the logic, providing the first decidability result for model checking a spatial logic with recursion.

  18. 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 fr...

  19. Military aviation noise:noise-induced hearing impairment and noise protection

    OpenAIRE

    Kuronen, P. (Pentti)

    2004-01-01

    Abstract This research on military aviation noise was conducted because the personnel working with military aircraft were concerned about noise induced hearing damage. In addition, comprehensive data on hearing impairments and occupational exposure of military pilots in the Finnish Air Force was not available. Moreover, data on the effects of overflight noise of military jets was necessary for the evaluation of noise induced hearing deteriorations of members of the ...

  20. Noise-induced coherent switch

    Institute of Scientific and Technical Information of China (English)

    YUAN ZhanJiang; ZHANG Jiadun; ZHOU TianShou

    2008-01-01

    Taking the famous genetic toggle switch as an example, we numerically investigated the effect of noise on bistability. We found that extrinsic noise resulting from stochastic fluctuations in synthesis and degradation rates and from the environmental fluctuation in gene regulatory processes can induce coherent switch, and that there is an optimal noise intensity such that the noise not only can induce this switch, but also can amplify a weak input signal. In addition, we found that the intrinsic noise introduced through the Poisson τ-leap algorithm cannot induce such a switch.

  1. Noise-induced coherent switch

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Taking the famous genetic toggle switch as an example,we numerically investigated the effect of noise on bistability.We found that extrinsic noise resulting from stochastic fluctuations in synthesis and degradation rates and from the environmental fluctuation in gene regulatory processes can induce coherent switch,and that there is an optimal noise intensity such that the noise not only can induce this switch,but also can amplify a weak input signal.In addition,we found that the intrinsic noise introduced through the Poisson τ-leap algorithm cannot induce such a switch.

  2. Noise-Mediated Generalized Synchronization

    Institute of Scientific and Technical Information of China (English)

    CHEN Yue-Hua; WU Zhi-Yuan; YANG Jun-Zhong

    2007-01-01

    @@ We investigate a drive-response system by considering the impacts of noise on generalized synchronization (GS).It is found that a small amount of noise can turn the system from desynchronization to the GS state in the resonant case no matter how noise is injected into the system. In the non-resonant case, noise with intensity in a certain range is helpful in building GS only when the noise is injected to the driving system. The mechanism behind the observed phenomena is discussed.

  3. Measurements techniques for transportation noise

    Energy Technology Data Exchange (ETDEWEB)

    Brambilla, G

    2001-07-01

    The noise from transport systems (roads, railways and aircraft) are increasing more and more both in space and in time and, therefore, they are still the major factor responsible for environmental noise pollution. The population exposed to transport noise is also increasing, and the corresponding health effects on people (i.e. annoyance and sleep disturbance) become more severe. Due to this current situation international and national legislation has been issued and implemented to reduce the harmful effects of such noise. This paper describes the techniques prescribed by recent Italian legislation to measure road, railway and aircraft noise. (author)

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

    OpenAIRE

    Sabine A. Janssen; Salomons, Erik M.

    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 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 o...

  5. Noise in the operating room

    DEFF Research Database (Denmark)

    Hasfeldt-Hansen, Dorthe; Lærkner, Eva Ann; Birkelund, Regner

    2010-01-01

    Because noise is a general stressor, noise in the OR should be avoided whenever possible. This article presents the results of a review of the research literature on the topic of noise in the OR. A systematic literature search was conducted. Eighteen relevant articles were identified...... to equipment and staff behavior. The main effect of noise on staff performances is related to impaired communication, resulting in a negative effect on patient safety. The literature on patients’ perception of noise is both limited and inconsistent, and more research on this topic is needed....

  6. Ambient temperature signalling in plants.

    Science.gov (United States)

    Wigge, Philip A

    2013-10-01

    Plants are exposed to daily and seasonal fluctuations in temperature. Within the 'ambient' temperature range (about 12-27°C for Arabidopsis) temperature differences have large effects on plant growth and development, disease resistance pathways and the circadian clock without activating temperature stress pathways. It is this developmental sensing and response to non-stressful temperatures that will be covered in this review. Recent advances have revealed key players in mediating temperature signals. The bHLH transcription factor PHYTOCHROME INTERACTING FACTOR4 (PIF4) has been shown to be a hub for multiple responses to warmer temperature in Arabidopsis, including flowering and hypocotyl elongation. Changes in chromatin state are involved in transmitting temperature signals to the transcriptome. Determining the precise mechanisms of temperature perception represents an exciting goal for the field.

  7. Noise levels at critical points in the municipality of Guadalajara, Jalisco, Mexico

    Science.gov (United States)

    Figueroa, Arturo; Garcia, Jesus; Macias, Jorge; Orozco, Martha; Garcia, Javier; Delgadillo, Alan

    2002-11-01

    Studies of acoustic conditions are planning tools on which we can diagnose the problem of noise pollution in the cities. The first study on noise pollution made in the city was made by the University of Guadalajara in 1995 and updated in 1998 covering with measuring points the city center. This paper discusses the problem of noise pollution by motor vehicles at critical points and covers a total of 105 points. The study also analyzes the problem of noise pollution base on the community annoyance from which a regulation policy should derive. Results of the study show that the most critical points are located within zone 1 (center) where Leq levels within the range of 70-85 dB were found. Such levels exceed by far the international standard of 65 dB as recommended for ambient noise by the World Health Organization.

  8. Measured Aperture-Array Noise Temperature of the Mark II Phased Array Feed for ASKAP

    CERN Document Server

    Chippendale, A P; Beresford, R J; Hampson, G A; Shaw, R D; Hayman, D B; Macleod, A; Forsyth, A R; Hay, S G; Leach, M; Cantrall, C; Brothers, M L; Hotan, A W

    2015-01-01

    We have measured the aperture-array noise temperature of the first Mk. II phased array feed that CSIRO has built for the Australian Square Kilometre Array Pathfinder telescope. As an aperture array, the Mk. II phased array feed achieves a beam equivalent noise temperature less than 40 K from 0.78 GHz to 1.7 GHz and less than 50 K from 0.7 GHz to 1.8 GHz for a boresight beam directed at the zenith. We believe these are the lowest reported noise temperatures over these frequency ranges for ambient-temperature phased arrays. The measured noise temperature includes receiver electronics noise, ohmic losses in the array, and stray radiation from sidelobes illuminating the sky and ground away from the desired field of view. This phased array feed was designed for the Australian Square Kilometre Array Pathfinder to demonstrate fast astronomical surveys with a wide field of view for the Square Kilometre Array.

  9. Relationship between container ship underwater noise levels and ship design, operational and oceanographic conditions

    Science.gov (United States)

    McKenna, Megan F.; Wiggins, Sean M.; Hildebrand, John A.

    2013-05-01

    Low-frequency ocean ambient noise is dominated by noise from commercial ships, yet understanding how individual ships contribute deserves further investigation. This study develops and evaluates statistical models of container ship noise in relation to design characteristics, operational conditions, and oceanographic settings. Five-hundred ship passages and nineteen covariates were used to build generalized additive models. Opportunistic acoustic measurements of ships transiting offshore California were collected using seafloor acoustic recorders. A 5-10 dB range in broadband source level was found for ships depending on the transit conditions. For a ship recorded multiple times traveling at different speeds, cumulative noise was lowest at 8 knots, 65% reduction in operational speed. Models with highest predictive power, in order of selection, included ship speed, size, and time of year. Uncertainty in source depth and propagation affected model fit. These results provide insight on the conditions that produce higher levels of underwater noise from container ships.

  10. 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.

  11. Signal recognition by frogs in the presence of temporally fluctuating chorus-shaped noise.

    Science.gov (United States)

    Vélez, Alejandro; Bee, Mark A

    2010-10-01

    The background noise generated in large social aggregations of calling individuals is a potent source of auditory masking for animals that communicate acoustically. Despite similarities with the so-called "cocktail-party problem" in humans, few studies have explicitly investigated how non-human animals solve the perceptual task of separating biologically relevant acoustic signals from ambient background noise. Under certain conditions, humans experience a release from auditory masking when speech is presented in speech-like masking noise that fluctuates in amplitude. We tested the hypothesis that females of Cope's gray treefrog (Hyla chrysoscelis) experience masking release in artificial chorus noise that fluctuates in level at modulations rates characteristic of those present in ambient chorus noise. We estimated thresholds for recognizing conspecific advertisement calls (pulse rate=40-50 pulses/s) in the presence of unmodulated and sinusoidally amplitude modulated (SAM) chorus-shaped masking noise. We tested two rates of modulation (5 Hz and 45 Hz) because the sounds of frog choruses are modulated at low rates (e.g., less than 5-10 Hz), and because those of species with pulsatile signals are additionally modulated at higher rates typical of the pulse rate of calls (e.g., between 15-50 Hz). Recognition thresholds were similar in the unmodulated and 5-Hz SAM conditions, and 12 dB higher in the 45-Hz SAM condition. These results did not support the hypothesis that female gray treefrogs experience masking release in temporally fluctuating chorus-shaped noise. We discuss our results in terms of modulation masking, and hypothesize that natural amplitude fluctuations in ambient chorus noise may impair mating call perception.

  12. Measurement and Characterization of Helicopter Noise at Different Altitudes

    Science.gov (United States)

    Watts, Michael E.; Greenwood, Eric; Stephenson, James

    2016-01-01

    This paper presents an overview of a flight test campaign performed at different test sites whose altitudes ranged from 0 to 7000 feet above mean sea level (AMSL) between September 2014 and February 2015. The purposes of this campaign were to: investigate the effects of altitude variation on noise generation, investigate the effects of gross weight variation on noise generation, establish the statistical variability in acoustic flight testing of helicopters, and characterize the effects of transient maneuvers on radiated noise for a medium-lift utility helicopter. In addition to describing the test campaign, results of the acoustic effects of altitude variation for the AS350 SD1 and EH-60L aircraft are presented. Large changes in acoustic amplitudes were observed in response to changes in ambient conditions when the helicopter was flown at constant indicated airspeed and gross weight at the three test sites. However, acoustic amplitudes were found to scale with ambient pressure when flight conditions were defined in terms of the non-dimensional parameters, such as the weight coefficient and effective hover tip Mach number.

  13. 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.

  14. Quantum Noise Locking

    OpenAIRE

    McKenzie, Kirk; Mikhailov, Eugeniy; Goda, Keisuke; Lam, Ping Koy; Grosse, Nicolai; Gray, Malcolm B.; Mavalvala, Nergis; McClelland, David E.

    2005-01-01

    Quantum optical states which have no coherent amplitude, such as squeezed vacuum states, can not rely on standard readout techniques to generate error signals for control of the quadrature phase. Here we investigate the use of asymmetry in the quadrature variances to obtain a phase-sensitive readout and to lock the phase of a squeezed vacuum state, a technique which we call noise locking (NL). We carry out a theoretical derivation of the NL error signal and the associated stability of the squ...

  15. Noise hazard course

    CERN Multimedia

    2003-01-01

    A 1/2 day course to promote awareness of the risks incurred by noise at the work place and recommendations to settle them. Next course Wednesday 24th September 2003. Costs are covered by TIS, Jacques Coillard from Bureau Véritas will present the course. Registration is obligatory. For more information and to enrol on this course go to the safety section of Human Resources Training and Development web pages, or contact : Ana-Paula Bernardes/TIS-GS (71385) or e-mail Ana-Paula.Bernardes@cern.ch

  16. Noise hazard course

    CERN Multimedia

    2003-01-01

    A 1/2 day course to promote awareness of the risks incurred by noise at the work place and recommendations to settle them. Next course Wednesday 24th September 2003. Costs are covered by TIS, Jacques Coillard from Bureau Véritas will present the course. Registration is obligatory. For more information and to enrol on this course go to the safety section of Human Resources Training and Development web pages, or contact: Ana-Paula Bernardes/TIS-GS (71385) or e-mail Ana-Paula.Bernardes@cern.ch

  17. Low noise constant current source for bias dependent noise measurements

    International Nuclear Information System (INIS)

    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.

  18. Oscillator PM Noise Reduction From Correlated AM Noise.

    Science.gov (United States)

    Hati, Archita; Nelson, Craig W; Howe, David A

    2016-03-01

    We demonstrate a novel technique for reducing the phase modulation (PM) noise of an oscillator in a steady-state condition as well as under vibration. It utilizes correlation between PM noise and amplitude modulation (AM) noise that can originate from the oscillator's loop components. A control voltage proportional to the correlated AM noise is generated and utilized in a feedforward architecture to correct for the steady state as well as the vibration-induced PM noise. An improvement of almost 10-15 dB in PM noise is observed over one decade of offset frequencies for a 635-MHz quartz-MEMS oscillator. This corresponds to more than a factor of five reductions in vibration sensitivity.

  19. Identification of Modal Parameters with Linear Structure under Non-stationary Ambient Excitation

    Institute of Scientific and Technical Information of China (English)

    续秀忠; 华宏星; 李中付; 陈兆能

    2004-01-01

    Empirical mode decomposition (EMD) is proposed to identify linear structure under non-stationary excitation,and non-white noise coefficient is introduced under the assumption of random signals consisting of white noise and non-white noise signals. The cross-correlation function of response signal is decomposed into mode functions and residue by EMD method. The identification technique of the modal parameters of single freedom degree is applied to each mode function to obtain natural frequencies, damping ratios and mode shapes. The results of identification of the five-degree freedom linear system demonstrate that the proposed method is effective in identifying the parameters of linear structures under non-stationary ambient excitation.

  20. Monitoring of Noise During Ganeshotsav

    Directory of Open Access Journals (Sweden)

    Mrs. P. Saler

    2011-09-01

    Full Text Available Sound is a form of energy emitted by a vibrating body causing change in pressure of the surrounding elastic medium through which energy is transmitted. Noise has been defined as unwanted sound. Noise is a disturbance to the human environment which is escalating at a high rate. There are numerous effects of noise on human and environment due to the increase in noise pollution slowly, insensibly; we seem to accept noise and the physiological and psychological deterioration that accompanies it as an inevitable part of our lives. Althoughattempts have been made to regulate noise pollution by setting standards for some of the major sources of noise, we often are unable to monitor them. One such source of noise in India is celebration of festival and especially in Maharashtra, the biggest festival- Ganeshostav. The way noise levels are increasing year by year during this festival, it seems we enjoy these sounds, though it has harmful effects on Human Health and Environment. This paper focuses on study of noise pollution during Ganesh Festival and also its other causes and effects.