WorldWideScience

Sample records for wind-generated ambient noise

  1. Acoustic ambient noise recorder

    Digital Repository Service at National Institute of Oceanography (India)

    Saran, A.K.; Navelkar, G.S.; Almeida, A.M.; More, S.R.; Chodankar, P.V.; Murty, C.S.

    with a robust outfit that can withstand high pressures and chemically corrosion resistant materials. Keeping these considerations in view, a CMOS micro-controller-based marine acoustic ambient noise recorder has been developed with a real time clock...

  2. Ambient Noise Characteristics During the Sheba Experiment

    National Research Council Canada - National Science Library

    Shaw, Ronald

    2000-01-01

    The ambient noise data recorded by two free-drifting buoys during the 1997-98 SHEBA experiment presented a unique opportunity to gauge the noise field of the Arctic Ocean in a unique and changing environment...

  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. Towards full waveform ambient noise inversion

    Science.gov (United States)

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

    2018-01-01

    In this work we investigate fundamentals of a method—referred to as full waveform ambient noise inversion—that improves the resolution of tomographic images by extracting waveform information from interstation correlation functions that cannot be used without knowing the distribution of noise sources. The fundamental idea is to drop the principle of Green function retrieval and to establish correlation functions as self-consistent observables in seismology. This involves the following steps: (1) We introduce an operator-based formulation of the forward problem of computing correlation functions. It is valid for arbitrary distributions of noise sources in both space and frequency, and for any type of medium, including 3-D elastic, heterogeneous and attenuating media. In addition, the formulation allows us to keep the derivations independent of time and frequency domain and it facilitates the application of adjoint techniques, which we use to derive efficient expressions to compute first and also second derivatives. The latter are essential for a resolution analysis that accounts for intra- and interparameter trade-offs. (2) In a forward modelling study we investigate the effect of noise sources and structure on different observables. Traveltimes are hardly affected by heterogeneous noise source distributions. On the other hand, the amplitude asymmetry of correlations is at least to first order insensitive to unmodelled Earth structure. Energy and waveform differences are sensitive to both structure and the distribution of noise sources. (3) We design and implement an appropriate inversion scheme, where the extraction of waveform information is successively increased. We demonstrate that full waveform ambient noise inversion has the potential to go beyond ambient noise tomography based on Green function retrieval and to refine noise source location, which is essential for a better understanding of noise generation. Inherent trade-offs between source and structure

  5. Ambient Noise in an Urbanized Tidal Channel

    Science.gov (United States)

    Bassett, Christopher

    In coastal environments, when topographic and bathymetric constrictions are combined with large tidal amplitudes, strong currents (> 2 m/s) can occur. Because such environments are relatively rare and difficult to study, until recently, they have received little attention from the scientific community. However, in recent years, interest in developing tidal hydrokinetic power projects in these environments has motivated studies to improve this understanding. In order to support an analysis of the acoustic effects of tidal power generation, a multi-year study was conducted at a proposed project site in Puget Sound (WA) are analyzed at a site where peak currents exceeded 3.5 m/s. From these analyses, three noise sources are shown to dominate the observed variability in ambient noise between 0.02-30 kHz: anthropogenic noise from vessel traffic, sediment-generated noise during periods of strong currents, and flow-noise resulting from turbulence advected over the hydrophones. To assess the contribution of vessel traffic noise, one calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site in northern Admiralty Inlet. The variability in spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband and M-weighted sound pressure levels is driven largely by vessel traffic. Within the one-year study period, at least one AIS transmitting vessel is present in the study area 90% of the time and over 1,363 unique vessels are recorded. A noise budget for vessels equipped with AIS transponders identifies cargo ships, tugs, and passenger vessels as the largest contributors to noise levels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessel types yields a cumulative probability density function of broadband sound pressure

  6. Ambient noise analysis of deep ocean measurements

    Science.gov (United States)

    Gaul, Roy D.; Knobles, David P.; Wittenborn, A. F.

    2004-05-01

    In October 1975 a measurement exercise designated CHURCH OPAL was done in the northeast Pacific Ocean to assess undersea acoustic noise and propagation phenomena. In 2003 the 10 days of deep ocean multiple hydrophone recordings during CHURCH OPAL were recovered and digitized. This paper presents results previously reported but unavailable for general distribution. The earlier work is augmented with more complete and detailed analyses using modern analytical techniques. Particular attention is given to statistical characterization of ambient noise within and beneath the deep sound channel in relation to distant shipping and local wind speed. [Work supported by ONR.

  7. Radial anisotropy ambient noise tomography of volcanoes

    Science.gov (United States)

    Mordret, Aurélien; Rivet, Diane; Shapiro, Nikolai; Jaxybulatov, Kairly; Landès, Matthieu; Koulakov, Ivan; Sens-Schönfelder, Christoph

    2016-04-01

    The use of ambient seismic noise allows us to perform surface-wave tomography of targets which could hardly be imaged by other means. The frequencies involved (~ 0.5 - 20 s), somewhere in between active seismic and regular teleseismic frequency band, make possible the high resolution imaging of intermediate-size targets like volcanic edifices. Moreover, the joint inversion of Rayleigh and Love waves dispersion curves extracted from noise correlations allows us to invert for crustal radial anisotropy. We present here the two first studies of radial anisotropy on volcanoes by showing results from Lake Toba Caldera, a super-volcano in Indonesia, and from Piton de la Fournaise volcano, a hot-spot effusive volcano on the Réunion Island (Indian Ocean). We will see how radial anisotropy can be used to infer the main fabric within a magmatic system and, consequently, its dominant type of intrusion.

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

    Science.gov (United States)

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

    2018-01-23

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

  9. Wind Generators and Market Power

    DEFF Research Database (Denmark)

    Misir, Nihat

    Electricity production from wind generators holds significant importance in European Union’s 20% renewable energy target by 2020. In this paper, I show that ownership of wind generators affects market outcomes by using both a Cournot oligopoly model and a real options model. In the Cournot...... oligopoly model, ownership of the wind generators by owners of fossil-fueled (peakload) generators decreases total peakload production and increases the market price. These effects increase with total wind generation and aggregate wind generator ownership. In the real options model, start up and shut down...

  10. Wind Generators and Market Power

    DEFF Research Database (Denmark)

    Misir, Nihat

    Electricity production from wind generators holds significant importance in European Union’s 20% renewable energy target by 2020. In this paper, I show that ownership of wind generators affects market outcomes by using both a Cournot oligopoly model and a real options model. In the Cournot...... oligopoly model, ownership of the wind generators by owners of fossil-fueled (peakload) generators decreases total peakload production and increases the market price. These effects increase with total wind generation and aggregate wind generator ownership. In the real options model, start up and shut down...... price thresholds are significantly higher when the monopolist at the peakload level owns both types of generators. Furthermore, when producing electricity with the peakload generator, the monopolist can avoid facing prices below marginal cost by owning a certain share of the wind generators....

  11. Ambient noise in large rivers (L).

    Science.gov (United States)

    Vračar, Miodrag S; Mijić, Miomir

    2011-10-01

    This paper presents the results of hydroacoustic noise research in three large European rivers: the Danube, the Sava, and the Tisa. Noise in these rivers was observed during a period of ten years, which includes all annual variation in hydrological and meteorological conditions (flow rate, speed of flow, wind speed, etc.). Noise spectra are characterized by wide maximums at frequencies between 20 and 30 Hz, and relatively constant slope toward higher frequencies. Spectral level of noise changes in time in relatively wide limits. At low frequencies, below 100 Hz, the dynamics of noise level is correlated with the dynamics of water flow and speed. At higher frequencies, noise spectra are mostly influenced by human activities on river and on riverbanks. The influence of wind on noise in rivers is complex due to the annual variation of river surface. The influence of wind is less pronounced than in oceans, seas, and lakes. © 2011 Acoustical Society of America

  12. Ambient noise levels and detection threshold in Norway.

    Science.gov (United States)

    Demuth, Andrea; Ottemöller, Lars; Keers, Henk

    2016-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Qiulong Yang

    2018-01-01

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

  14. Global-scale Full Waveform Ambient Noise Inversion

    Science.gov (United States)

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

    2017-12-01

    In earthquake tomography, modern tomographic methods exploit waveforms for the benefit of improved resolution. However, these techniques cannot be applied to noise correlation functions without knowing the distribution of noise sources. To overcome this limitation, we develop a method - referred to as full waveform ambient noise inversion - that is valid for arbitrary noise source distributions in both space and frequency, accounts for 3D heterogeneous and attenuating media and the full seismic wave propagation physics. The fundamental idea is to drop the principle of Green function retrieval, which is the basis for current noise tomographic studies, and to establish correlation functions as self-consistent observables in seismology. Based on a synthetic study in 2D, investigating the prerequisites for a joint inversion for noise sources and Earth structure, we extend the open-source waveform modelling and inversion package Salvus (http://salvus.io). It allows us to compute correlation functions in 3D media with heterogeneous noise sources at the surface and the corresponding sensitivity kernels for the distribution of noise sources and Earth structure. We present sensitivity kernels for different cross-correlation time lags and various noise source distributions, and study the effect of 3D heterogeneous Earth structure. For a validation of full waveform ambient noise inversion, we apply it to a global dataset focusing on the Earth's hum period band.

  15. Eastern Arctic ambient noise on a drifting vertical array.

    Science.gov (United States)

    Ozanich, Emma; Gerstoft, Peter; Worcester, Peter F; Dzieciuch, Matthew A; Thode, Aaron

    2017-10-01

    Ambient noise in the eastern Arctic was studied from April to September 2013 using a 22 element vertical hydrophone array as it drifted from near the North Pole (89° 23'N, 62° 35'W) to north of Fram Strait (83° 45'N, 4° 28'W). The hydrophones recorded for 108 min/day on six days per week with a sampling rate of 1953.125 Hz. After removal of data corrupted by non-acoustic transients, 19 days throughout the transit period were analyzed. Noise contributors identified include broadband and tonal ice noises, bowhead whale calling, seismic airgun surveys, and earthquake T phases. The bowhead whale or whales detected are believed to belong to the endangered Spitsbergen population, and were recorded when the array was as far north as 86° 24'N. Median power spectral estimates and empirical probability density functions along the array transit show a change in the ambient noise levels corresponding to seismic survey airgun occurrence and received level at low frequencies and transient ice noises at high frequencies. Median power for the same periods across the array shows that this change is consistent in depth. The median ambient noise for May 2013 was among the lowest of the sparse reported observations in the eastern Arctic but comparable to the more numerous observations of western Arctic noise levels.

  16. The persistent signature of tropical cyclones in ambient seismic noise

    Science.gov (United States)

    Gualtieri, Lucia; Camargo, Suzana J.; Pascale, Salvatore; Pons, Flavio M. E.; Ekström, Göran

    2018-02-01

    The spectrum of ambient seismic noise shows strong signals associated with tropical cyclones, yet a detailed understanding of these signals and the relationship between them and the storms is currently lacking. Through the analysis of more than a decade of seismic data recorded at several stations located in and adjacent to the northwest Pacific Ocean, here we show that there is a persistent and frequency-dependent signature of tropical cyclones in ambient seismic noise that depends on characteristics of the storm and on the detailed location of the station relative to the storm. An adaptive statistical model shows that the spectral amplitude of ambient seismic noise, and notably of the short-period secondary microseisms, has a strong relationship with tropical cyclone intensity and can be employed to extract information on the tropical cyclones.

  17. The persistent signature of tropical cyclones in ambient seismic noise

    KAUST Repository

    Gualtieri, Lucia

    2017-12-28

    The spectrum of ambient seismic noise shows strong signals associated with tropical cyclones, yet a detailed understanding of these signals and the relationship between them and the storms is currently lacking. Through the analysis of more than a decade of seismic data recorded at several stations located in and adjacent to the northwest Pacific Ocean, here we show that there is a persistent and frequency-dependent signature of tropical cyclones in ambient seismic noise that depends on characteristics of the storm and on the detailed location of the station relative to the storm. An adaptive statistical model shows that the spectral amplitude of ambient seismic noise, and notably of the short-period secondary microseisms, has a strong relationship with tropical cyclone intensity and can be employed to extract information on the tropical cyclones.

  18. Accurate Ambient Noise Assessment Using Smartphones

    Science.gov (United States)

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

    2017-01-01

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

  19. Accurate Ambient Noise Assessment Using Smartphones.

    Science.gov (United States)

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

    2017-04-21

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

  20. Ambient Seismic Noise Tomography of Southern Norway

    Science.gov (United States)

    Köhler, Andreas; Weidle, Christian; Maupin, Valerie

    2010-05-01

    The noise cross-correlation technique is especially useful in regions like southern Norway since local seismicity is rare and teleseismic records are not able to resolve the upper crust. Within the TopoScandiaDeep project, which aims to investigate the relation between surface topography and lithosphere-asthenosphere structure, we process seismic broadband data from the temporary MAGNUS network in Southern Norway. The receivers were recording 20 months of continuous data between September 2006 and June 2008. Additionally, permanent stations of the National Norwegian Seismic Network, NORSAR and GSN stations in the region are used. After usual preprocessing steps (filtering, prewhitening, temporal normalization), we compute 820 cross-correlation functions from 41 receivers for three month time windows. Evaluation of the azimuthal and temporal variation of signal to noise ratios and f-k analysis of NORSAR array data shows that the dominant propagation direction of seismic noise is south-west to north, corresponding well to the Norwegian coast line. During summer months, the signal to noise ratios decrease and the azimuthal distribution becomes smoother. Time-frequency analysis is applied to measure Rayleigh and Love wave group velocity dispersion curves between each station pair for each three-month correlation stack. The mean and variance of all dispersion curves is computed for each path. After rejection of low-quality data using a signal to noise ratio, minimum wavelength and velocity variance criterion, we obtain a large number of reliable velocity estimates (about 600) for periods between 2 and 15 seconds, which we invert for group velocity maps at respective periods. At all inverted periods, we find positive and negative velocity anomalies for Rayleigh and Love waves that correlate very well with local surface geology. While higher velocities (+5%) can be associated with the Caledonian nappes in the central part of southern Norway, the Oslo Graben is reflected

  1. Evidence of Non-extensivity in Earth's Ambient Noise

    Science.gov (United States)

    Koutalonis, Ioannis; Vallianatos, Filippos

    2017-12-01

    The study of ambient seismic noise is one of the important scientific and practical research challenges, due to its use in a number of geophysical applications. In this work, we describe Earth's ambient noise fluctuations in terms of non-extensive statistical physics. We found that Earth's ambient noise increments follow the q-Gaussian distribution. This indicates that Earth's ambient noise's fluctuations are not random and present long-term memory effects that could be described in terms of Tsallis entropy. Our results suggest that q values depend on the time length used and that the non-extensive parameter, q, converges to value q → 1 for short-time windows and a saturation value of q ≈ 1.33 for longer ones. The results are discussed from the point of view of superstatistics introduced by Beck [Contin Mech Thermodyn 16(3):293-304, 2004] and connects the q values with the system's degrees of freedom. Our work indicates that the converged (maximum) value is q = 1.33 and is related to 5 degrees of freedom.

  2. Qademah Fault Artificial Ambient Noise Test

    KAUST Repository

    Hanafy, Sherif M.

    2014-01-01

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

  3. 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.

  4. Amplification and Attenuation across USArray using Ambient Noise Wavefront Tracking

    KAUST Repository

    Bowden, Daniel C.

    2017-11-15

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

  5. 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

  6. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Monitoring and imaging the atmosphere with infrasonic ambient noise correlations

    Science.gov (United States)

    Haney, Matthew; Evers, Laslo

    2010-05-01

    The existence of widespread infrasonic ambient noise (e.g., microbaroms) opens up the possibility of investigating atmospheric acoustic structure with new techniques designed for continuous stochastic signals. This is in contrast to classical approaches that use deterministic signals (e.g., explosions) with clear phase arrivals. Here, we review some recent advances in the monitoring and imaging of the atmosphere derived from analysis of continuous infrasound noise. From two microbarometers located at Fourpeaked Volcano in Alaska, we observe coherent arrivals in cross-correlations of ambient noise in the microbarom band (0.2-0.5 Hz) at time lags that agree well with speeds expected for a direct infrasound wave in the atmosphere (300-340 m/s). A striking example of the dependence of the ambient noise correlations on atmospheric conditions is evident from a comparison with temperature and wind data measured on nearby ocean buoys. Application of the multiple-filter technique reveals that the group velocity of the infrasound wave is dispersive, with higher group velocities at lower frequencies. This supports the existence of a low-level atmospheric waveguide at Fourpeaked Volcano during the time period under study. We invert the observed time-dependent group velocity dispersion curves for average sound speed profiles as a function of time. The inverted sound speed profiles show that a time-dependent, surface-based inversion layer became stronger over a period of 24 hours, with a colder, denser, and lower sound speed layer moving between the stations. This layer is imaged in the lower 2 km of the atmosphere and demonstrates the sensitivity of ambient noise correlations to the atmospheric boundary layer. Independent analysis of meteorological data in and around Fourpeaked volcano from the same time period supports the results derived from the infrasound ambient noise correlations. We also show examples of ambient noise correlations from time periods of normal temperature

  8. Three-component ambient noise beamforming in the Parkfield area

    Science.gov (United States)

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

    2018-02-01

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

  9. An intelligent subsurface buoy design for measuring ocean ambient noise

    Science.gov (United States)

    Li, Bing; Wang, Lei

    2012-11-01

    A type of ultra-low power subsurface buoy system is designed to measure and record ocean ambient noise data. The buoy utilizes a vector hydrophone (pass band 20Hz-1.2kHz) and a 6-element vertical hydrophone array (pass band 20Hz-2kHz) to measure ocean ambient noise. The acoustic signals are passed through an automatically modified gain, a band pass filter, and an analog-to-digital (A/D) conversion module. They are then stored in high-capacity flash memory. In order to identify the direction of noise source, the vector sensor measuring system has integrated an electric-magnetic compass. The system provides a low-rate underwater acoustic communication system which is used to report the buoy state information and a high-speed USB interface which is used to retrieve the recorded data on deck. The whole system weighs about 125kg and can operate autonomously for more than 72 hours. The system's main architecture and the sea-trial test results are provided in this paper.

  10. Ambient noise levels and characterization in Aegean region, Turkey

    Science.gov (United States)

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

    2018-03-01

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

  11. Ambient noise levels and characterization in Aegean region, Turkey

    Science.gov (United States)

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

    2017-12-01

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

  12. Noise Model Analysis and Estimation of Effect due to Wind Driven Ambient Noise in Shallow Water

    Directory of Open Access Journals (Sweden)

    S. Sakthivel Murugan

    2011-01-01

    Full Text Available Signal transmission in ocean using water as a channel is a challenging process due to attenuation, spreading, reverberation, absorption, and so forth, apart from the contribution of acoustic signals due to ambient noises. Ambient noises in sea are of two types: manmade (shipping, aircraft over the sea, motor on boat, etc. and natural (rain, wind, seismic, etc., apart from marine mammals and phytoplanktons. Since wind exists in all places and at all time: its effect plays a major role. Hence, in this paper, we concentrate on estimating the effects of wind. Seven sets of data with various wind speeds ranging from 2.11 m/s to 6.57 m/s were used. The analysis is performed for frequencies ranging from 100 Hz to 8 kHz. It is found that a linear relationship between noise spectrum and wind speed exists for the entire frequency range. Further, we developed a noise model for analyzing the noise level. The results of the empirical data are found to fit with results obtained with the aid of noise model.

  13. 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.

  14. Ambient noise tomography of Eyjafjallajökull volcano, Iceland

    Science.gov (United States)

    Benediktsdóttir, Ásdís; Gudmundsson, Ólafur; Brandsdóttir, Bryndís; Tryggvason, Ari

    2017-11-01

    We present a shear-velocity model for the Eyjafjallajökull stratovolcano, based on ambient seismic noise tomography applied to seven months of data from six permanent stations and 10 temporary seismic stations, deployed during and after the 2010 volcanic unrest. Vertical components of noise were cross correlated resulting in 30 robust phase-velocity dispersion curves between 1.6 and 6.5 s in period, displaying a ± 20% variation in phase velocity beneath the volcano. The uneven distribution of noise sources, evaluated using signal-to-noise ratios, was estimated to cause less than 2% error in most curves. Sensitivity kernels showed resolution down to 10 km and the lateral resolution of the resulting phase-velocity maps was about 5 km. The model reveals east-west oriented high-velocity anomalies due east and west of the caldera. Between these a zone of lower velocity is identified, coinciding with the location of earthquakes that occurred during the summit eruption in April 2010. A shallow, southwest elongated low-velocity anomaly is located 5 km southwest of the caldera. The limited depth resolution of the shear-velocity model precludes detection of melt within the volcano.

  15. Thirty years of progress in applications and modeling of ocean ambient noise

    Science.gov (United States)

    Siderius, Martin; Buckingham, Michael J.

    2012-11-01

    Ambient noise in the ocean is a stochastic process, which traditionally was considered to be a nuisance, since it reduced the detectability of sonar signals of interest. However, over the last thirty years, it has come to be recognized that the ambient noise itself contains useful information about the ocean and ocean processes. To extract the information, various inversion procedures have been developed, based upon which a number of practical applications of the ambient noise have evolved. Since naturally generated ambient noise is always present in the ocean, it has the advantage of being non-invasive and non-damaging to marine life, including marine mammals. In this article, a summary of the commonly encountered ambient noise models is offered, along with the associated inversion procedures, and some of the more recent applications of the ambient noise are highlighted.

  16. DESIGN ASPECTS OF A RESIDENTIAL WIND GENERATOR

    Directory of Open Access Journals (Sweden)

    C. BRAD

    2017-03-01

    Full Text Available In this paper we present some aspects about the design of a small permanent magnet wind generator with axial magnetic flux often used in residential wind turbine. There are summarised the main steps of the magnetic and electric calculations with applications to a particular case: 0.6 kVA wind generator. The axial flux wind generator design starts with the characteristics of the rare earths permanent magnet existing on the market.

  17. Body Wave and Ambient Noise Tomography of Makushin Volcano, Alaska

    Science.gov (United States)

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

    2017-12-01

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

  18. Transdimensional, hierarchical, Bayesian inversion of ambient seismic noise: Australia

    Science.gov (United States)

    Crowder, E.; Rawlinson, N.; Cornwell, D. G.

    2017-12-01

    We present models of crustal velocity structure in southeastern Australia using a novel, transdimensional and hierarchical, Bayesian inversion approach. The inversion is applied to long-time ambient noise cross-correlations. The study area of SE Australia is thought to represent the eastern margin of Gondwana. Conflicting tectonic models have been proposed to explain the formation of eastern Gondwana and the enigmatic geological relationships in Bass Strait, which separates Tasmania and the mainland. A geologically complex area of crustal accretion, Bass Strait may contain part of an exotic continental block entrained in colliding crusts. Ambient noise data recorded by an array of 24 seismometers is used to produce a high resolution, 3D shear wave velocity model of Bass Strait. Phase velocity maps in the period range 2-30 s are produced and subsequently inverted for 3D shear wave velocity structure. The transdimensional, hierarchical Bayesian, inversion technique is used. This technique proves far superior to linearised inversion. The inversion model is dynamically parameterised during the process, implicitly controlled by the data, and noise is treated as an inversion unknown. The resulting shear wave velocity model shows three sedimentary basins in Bass Strait constrained by slow shear velocities (2.4-2.9 km/s) at 2-10 km depth. These failed rift basins from the breakup of Australia-Antartica appear to be overlying thinned crust, where typical mantle velocities of 3.8-4.0 km/s occur at depths greater than 20 km. High shear wave velocities ( 3.7-3.8 km/s) in our new model also match well with regions of high magnetic and gravity anomalies. Furthermore, we use both Rayleigh and Love wave phase data to to construct Vsv and Vsh maps. These are used to estimate crustal radial anisotropy in the Bass Strait. We interpret that structures delineated by our velocity models support the presence and extent of the exotic Precambrian micro-continent (the Selwyn Block) that was

  19. Ambient and at-the-ear occupational noise exposure and serum lipid levels

    DEFF Research Database (Denmark)

    Arlien-Søborg, Mai C; Schmedes, Astrid S; Stokholm, Z A

    2016-01-01

    -the-ear occupational noise exposure and serum levels of total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and triglycerides when accounting for well-established predictors of lipid levels. METHODS: This cross-sectional study included 424 industrial workers and 84 financial...... workers to obtain contrast in noise exposure levels. They provided a serum sample and wore portable dosimeters that every 5-s recorded ambient noise exposure levels during a 24-h period. We extracted measurements obtained during work and calculated the full-shift mean ambient noise level. For 331 workers...... who kept a diary on the use of a hearing protection device (HPD), we subtracted 10 dB from every noise recording obtained during HPD use and estimated the mean full-shift noise exposure level at the ear. RESULTS: Mean ambient noise level was 79.9 dB (A) [range 55.0-98.9] and the mean estimated level...

  20. Ambient Noise Tomography in Koyna-Warna region.

    Science.gov (United States)

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

    2017-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-06-30

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

  2. Circadian Rhythm of Ambient Noise Off the Southeast Coast of India

    Science.gov (United States)

    Kannan, R.; Latha, G.; Prashanthi Devi, M.

    An ambient noise system consisting of a vertical linear hydrophone array was deployed in the shallow waters off Chennai, southeast coast of India from 1 August to 16 September 2013 to record ambient ocean noise of frequencies up to 10kHz. Biological sounds, which are broadband, short duration signals resulting from Terapon theraps, a native species, are a prominent feature of the ocean soundscape. Terapon activity peaks at 8pm and 11pm, and its presence is not observed after 12 midnight in both the months. In the other period, the ambient noise fluctuation is due to wind and vessel traffic. Hence, the present study focuses on the description of the ambient noise fluctuation over two 12h periods, i.e., 12 midnight-12 noon considered as period I, and 12 noon-12 midnight as period II in order to show the circadian rhythm of ambient noise. In this study area, Terapon vocalization reached 25dB above the ambient noise level and it dominates the short-term spectra records in the 0.4-4kHz range. All Terapon signals had daily patterns of sound production with highest levels of activity after dusk during the study period. The result shows that the circadian rhythm of ambient noise is mainly of biological sound generated by Terapon and it is reported first time in the shallow waters off the southeast coast of India.

  3. Wind generator with electronic variable-speed drives

    Energy Technology Data Exchange (ETDEWEB)

    David, A.; Buchheit, N.; Jakobsen, H.

    1996-12-31

    Variable speed drives have been inserted between the network and the generator on certain recent wind power facilities. They have the following advantages: the drive allows the wind generator to operate at low speed with a significant reduction in acoustic noise, an important point if the facilities are sited near populated areas; the drive optimizes energy transfer, providing a gain of 4 to 10 %; the drive can possibly replace certain mechanical parts (the starting system and it in some cases, the reduction gear); the drive not only provides better transient management in relation to the network for less mechanical stress on the wind generator, it is also able to control reactive power. One commercial drive design sold by several manufacturers has already been installed on several wind generators with outputs of between 150 and 600 kw. In addition, such a solution is extremely well suited to mixed renewable energy systems. This design uses two inverse rectifier type converters and can therefore exchange energy in both directions. The equivalent drive with a single IGBT converter on the motor side and a diode converter on the network side is the solution most widely adopted throughout industry (with more than 50, 000 units installed in France per year). It still remains to be seen whether such a solution could be profitable in wind generator application (since the cost of the drive is quite high). This technical analysis is more destined for the converter-machine assembly specialists and is presented in this document, paying particular attention as it does to the modelling of the `wind energy - generator - drive - network` assembly, the associated drive command and control strategies and the simulations obtained during various transients. A 7.5 kW test bed has been installed in the Laboratoire d`Electronique de Puissance de Clamart, enabling tests to be carried out which emulate the operation of a wind generator.

  4. 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.

  5. The influence of ambient noise on maternal behavior in a Bornean sun bear (Helarctos malayanus euryspilus).

    Science.gov (United States)

    Owen, Megan A; Hall, Suzanne; Bryant, Lisa; Swaisgood, Ronald R

    2014-01-01

    Anthropogenic noise has become a pervasive feature of both marine and terrestrial habitats worldwide. While a comprehensive understanding of the biologically significant impacts of noise on wildlife is lacking, concerns regarding its influence persist. Noise is also a common feature in the zoological setting, and much can be learned regarding the species-typical response to ambient noise by studying animals in captivity. Here we correlate behavioral and vocal patterns in a Bornean sun bear (Helarctos malayanus euryspilus) mother and cub with ambient noise levels during the 6-month post-partum period. We hypothesized that loud ambient noise would be correlated with changes in behavior, and predicted that noise would be negatively correlated with maternal care behavior, potentially masking cub vocalizations or providing a distraction to the mother. Contrary to expectation, we found that the mother spent significantly more time attending to her cub (P=0.03) on loud days. We also found that she tended to spend less time feeding (P=0.08); however her time spent resting was not affected. The cub was approximately twice as vocal on loud days, although these results were not statistically significant (humming: P=0.10; squawks/cries: P=0.14). Taken together, these results suggest that the behavioral response to ambient noise may have potential energetic costs, and as a result efforts should be made to reduce ambient noise exposure during the post-partum period. © 2013 Wiley Periodicals, Inc.

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

    Directory of Open Access Journals (Sweden)

    Sonia R. B D'Souza

    2017-10-01

    Full Text Available Background: Advances in neonatal care have resulted in improved survival of neonates admitted to the intensive care of the Neonatal Intensive Care Unit (NICU. However, the NCU may be an inappropriate milieu, with presence of overwhelming stimuli, most potent being the continuous presence of noise in the ambience of the NICU. Aim and Objectives: To determine and describe the ambient noise levels in the acute NICU of a tertiary referral hospital. Material and Methods: The ambient noise, in this study was the background sound existing in the environment of the acute NICU of a tertiary referral hospital in South India. The ambient noise levels were analyzed by an audiologist and acoustical engineer using a standardized and calibrated Sound Level Meter (SLM i.e., the Hand Held Analyzer type 2250, Brüel and Kjær, Denmark on a weighted frequency A and reported as dB (A. Results: The ambient noise levels were timed measurements yielded by the SLM in terms of L eq, L as well as L exceeded the standard A 10 Aeqmax levels (Leq< 45 dB, L ≤ 50 dB, and Lmax ≤ 65 10 dB.The L eq ranged from 59.4 to 62.12 dB A. A Ventilators with alarms caused the maximum amount of ambient noise yielding a L Sound Pressure Level AF (SPL of 82.14 dB A. Conclusion: The study has found high levels of ambient noise in the acute NICU. Though there are several measures to reduce the ambient noise levels in the NICU, it is essential to raise awareness among health care personnel regarding the observed ambient noise levels and its effects on neonates admitted to the NICU.

  7. Potential Impacts of Ambient Noise in the on Marine Mammals

    National Research Council Canada - National Science Library

    Frisk, George

    2003-01-01

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

  8. Wind Generation Feasibility Study in Bethel, AK

    Energy Technology Data Exchange (ETDEWEB)

    Tom Humphrey, YKHC; Lance Kincaid, EMCOR Energy & Technologies

    2004-07-31

    This report studies the wind resources in the Yukon-Kuskokwim Health Corporation (YKHC) region, located in southwestern Alaska, and the applicability of wind generation technologies to YKHC facilities.

  9. Rayleigh wave tomography in North-China from ambient seismic noise

    OpenAIRE

    Fang, Lihua

    2010-01-01

    2008/2009 The theory and methodology of ambient noise tomography has been studied and applied to North-China successfully. Continuous vertical-component seismograms, spanning the period from January 1, 2007 to February 28, 2008 recorded by 190 broadband stations and 10 very broadband stations, have been used. The cross correlation technique has been applied to ambient noise data recorded by North-China Seismic Array for each station pairs of the array. Rayleigh wave group ve...

  10. 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.

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  12. Ambient-noise tomography of Katla volcano, south Iceland

    Science.gov (United States)

    Jeddi, Zeinab; Gudmundsson, Olafur; Tryggvason, Ari

    2017-11-01

    A shear-wave velocity model of subglacial Katla volcano, southern Iceland, has been developed using ambient seismic noise tomography based on data from a temporary network operating between May 2011 and August 2013 and permanent stations around the volcano. Phase-velocity dispersion curves were obtained using cross-correlations of vertical components of 136 station pairs and non-linearly inverted for phase-velocity maps between 1.7 and 7.5 s. Local dispersion curves were inverted for shear-velocity variation with depth using a grid search imposing a fixed ice layer at the top. The resulting one-dimensional (1-D) velocity models were combined to obtain a pseudo three-dimensional (3-D) model with estimated lateral resolution of 8 km and depth resolution varying from close to 1 km near the surface to about 8 km at 10 km depth. Shear wave velocities are generally higher within the Katla central volcano than in its surroundings. The most striking feature of the model is a high-velocity anomaly beneath the caldera at > 6 km depth interpreted to be due to cumulates resulting from differentiation of shallower magma intrusions and remelting of subsiding upper crust. No shallow low-velocity anomaly is resolved beneath the central caldera, but a low-velocity region is found at 2-4 km depth beneath the western half of the caldera. VP/VS ratios, estimated from average velocity-depth profiles from surface-wave data and higher frequency P-wave data, are anomalously high (> 1.9) compared to average Icelandic crust, particularly in the top 2-3 km. This is argued not to be an artifact due to lateral refraction or topography. Instead, this anomaly could be explained as an artifact caused by velocity dispersion due to attenuation and a difference in frequency content, and possibly to a degree by the compositional difference between the transalkalic Fe-Ti basalts of Katla and average tholeiitic Icelandic crust.

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

    Science.gov (United States)

    Tian, Ye; Ritzwoller, Michael H.

    2017-09-01

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

  14. Electrical and noise characteristics of graphene field-effect transistors: ambient effects, noise sources and physical mechanisms.

    Science.gov (United States)

    Rumyantsev, S; Liu, G; Stillman, W; Shur, M; Balandin, A A

    2010-10-06

    We fabricated a large number of single and bilayer graphene transistors and carried out a systematic experimental study of their low-frequency noise characteristics. Special attention was given to determining the dominant noise sources in these devices and the effect of aging on the current-voltage and noise characteristics. The analysis of the noise spectral density dependence on the area of graphene channel showed that the dominant contributions to the low-frequency electronic noise come from the graphene layer itself rather than from the contacts. Aging of graphene transistors due to exposure to ambient conditions for over a month resulted in substantially increased noise, attributed to the decreasing mobility of graphene and increasing contact resistance. The noise spectral density in both single and bilayer graphene transistors either increased with deviation from the charge neutrality point or depended weakly on the gate bias. This observation confirms that the low-frequency noise characteristics of graphene transistors are qualitatively different from those of conventional silicon metal-oxide-semiconductor field-effect transistors.

  15. Spatial correlation in the ambient core noise field of a turbofan engine.

    Science.gov (United States)

    Miles, Jeffrey Hilton

    2012-06-01

    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 NO(x) 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.

  16. Improving Seismic Velocity Models with Constraints from Autocorrelation of Ambient Seismic Noise and Signal

    Science.gov (United States)

    2016-03-24

    AFRL-RV-PS- AFRL-RV-PS- TR-2016-0098 TR-2016-0098 IMPROVING SEISMIC VELOCITY MODELS WITH CONSTRAINTS FROM AUTOCORRELATION OF AMBIENT SEISMIC ...TYPE Final Report 3. DATES COVERED (From - To) 24 Apr 2014 – 24 Mar 2016 4. TITLE AND SUBTITLE Improving Seismic Velocity Models with Constraints from...Autocorrelation of Ambient Seismic Noise and Signal 5a. CONTRACT NUMBER FA9453-14-C-0214 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62601F 6

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

    Science.gov (United States)

    Frisk, George V

    2012-01-01

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

  18. Self-organizing map and its application in the analysis of ambient noise characteristics

    Science.gov (United States)

    Meng, Chunxia; Li, Guijuan; Che, Shuwei; Bai, Jin

    2017-01-01

    The Self-organizing map (SOM) is an unsupervised neural network based on competitive learning, and can solve the problem that the center of clustering is unknown. SOM's theory and the implementation of algorithm are studied in this paper. Simulating example is given to approve the feasibility of SOM in characteristic assessment for multivariate sample. The Ambient sea noise measurement is made in August 2014 on some sea of China. The total source level was forecasted using "ROSS formula" and the sailing information. The statistical variability of broadband ambient noise at frequencies between 20Hz and 31.5 kHz is obtained using SOM. The comparison between measured sound pressure and forecasting pressure is given, and the preliminary analysis of the relationship between ambient noise level and vessels is carried out. The results provide the technical reference to understand the temporal and spatial statistical variability of ambient noise, and are an efficient tool in assessing the potential effect of shipping noise on marine mammals in the special sea area.

  19. ARE660 Wind Generator: Low Wind Speed Technology for Small Turbine Development

    Energy Technology Data Exchange (ETDEWEB)

    Robert W. Preus; DOE Project Officer - Keith Bennett

    2008-04-23

    This project is for the design of a wind turbine that can generate most or all of the net energy required for homes and small businesses in moderately windy areas. The purpose is to expand the current market for residential wind generators by providing cost effective power in a lower wind regime than current technology has made available, as well as reduce noise and improve reliability and safety. Robert W. Preus’ experience designing and/or maintaining residential wind generators of many configurations helped identify the need for an improved experience of safety for the consumer. Current small wind products have unreliable or no method of stopping the wind generator in fault or high wind conditions. Consumers and their neighbors do not want to hear their wind generators. In addition, with current technology, only sites with unusually high wind speeds provide payback times that are acceptable for the on-grid user. Abundant Renewable Energy’s (ARE) basic original concept for the ARE660 was a combination of a stall controlled variable speed small wind generator and automatic fail safe furling for shutdown. The stall control for a small wind generator is not novel, but has not been developed for a variable speed application with a permanent magnet alternator (PMA). The fail safe furling approach for shutdown has not been used to our knowledge.

  20. Effects of bladdered fish on ambient noise measurements close to the port of Rotterdam

    NARCIS (Netherlands)

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

    2011-01-01

    Ambient noise in the frequency range 25 Hz to 80 kHz was measured at a site close to the Port of Rotterdam in September 2008, before construction began of a port extension known as ‘Maasvlakte 2’ [http://www.maasvlakte2.com/en/index/], and in September-October 2009 (during construction). Day-night

  1. Horizontal Directionality of Ambient Sea Noise in the North Pacific Ocean

    Science.gov (United States)

    1976-05-01

    interpreting the horizontal directionalit- of the ambient noise shown in figures 11, 12" and 13. This location was in the transpacific shipping lanes...types of errors encountered when determining horizontal arrival angles for the beam response data. The first is due to the angular nature of both the

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

    Czech Academy of Sciences Publication Activity Database

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

    2016-01-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

    2016-01-01

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

  4. 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

  5. The crustal structure beneath The Netherlands derived from ambient seismic noise

    NARCIS (Netherlands)

    Yudistira, Tedi; Paulssen, Hanneke; Trampert, Jeannot

    2017-01-01

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

  6. The crustal structure beneath the Netherlands inferred from ambient seismic noise

    NARCIS (Netherlands)

    Yudistira, T.

    2015-01-01

    A 3-D shear velocity model of the crust beneath the Netherlands is determined from fundamental mode Rayleigh and Love wave group measurements derived from ambient seismic noise recordings. The data are obtained from a temporary array of broad-band seismometers in and around the Netherlands (the

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

    Science.gov (United States)

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

    2014-10-01

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

  8. High ambient noise levels in Vadodara City, India, affected by urbanization.

    Science.gov (United States)

    Singh, Neha; Dhiman, Hitesh; Shaikh, Sadaf; Shah, Purvish; Sarkar, Roma; Patel, Shashin

    2016-12-01

    The present research was conducted to study the urbanization of Vadodara city and to monitor the ambient noise level in the industrial, commercial, residential and silence zones of the city. A settlement map created by unsupervised classification for the land use and land cover study of Vadodara city clearly shows the increasing pattern of urbanization in its central part, which may be the result of urban sprawl due to migration of people from the rural to the urban areas. The fluctuation in ambient noise level was recorded using an A-weighted sound level meter in all the four zones of Vadodara city for 3 h at regular intervals of 15 min on 3 consecutive days at the same time. The results showed the highest equivalent noise level of 93.7 dBA in the commercial zone followed by 85.5 dBA in the industrial zone, 73.2 dBA in silence zone, and 70.2 dBA in the residential zone. The values of noise level were high in all the zones of the city increasing remarkably over the prescribed limit given in the Noise Pollution (Control and Regulation) Rules, 2000. Continuous exposure to such high level of noise may lead to detrimental effect on people.

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

    Science.gov (United States)

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

    2017-11-01

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

  10. 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.

  11. Icequakes and ambient noise sources detected by a geophone array at the Kaskawulsh glacier

    Science.gov (United States)

    Aso, N.; Tsai, V. C.; Schoof, C.; Whiteford, A.; Flowers, G. E.

    2015-12-01

    Both sliding and meltwater drainage processes of glaciers are expected to generate seismic signals. The confluence of the North and Central arms of the Kaskawulsh glacier in the Yukon Territory is an especially attractive place to study such phenomena not only because of the confluence but also because a nearby ice-dammed lake fills and drains rapidly every summer. We analyzed geophone data from nine stations at the Kaskawulsh glacier during the summer of 2014 to detect and locate icequakes and ambient noise sources. We first detected icequakes automatically by picking arrivals. Then we located events using differential arrival times between stations obtained precisely by cross-correlations, and also applied a double-difference relocation technique. During the 1-month observation period, we found 183 events that clustered near the medial moraine. More icequakes are observed from midnight to noon, potentially due to lower noise levels. These events are distributed on a dipping plane sub-parallel to the glacier flow direction. The depths below the surface range from 200m on the shallower side to 500m on the deeper side. This structure may correspond to the basal slope of the medial moraine and implies that these icequake signals come from either shear basal sliding or an englacial splay fault. We also determined ambient noise source locations for each 1-hour record sequence using the same process as for the icequakes. We located 31 sequences, among which more sequences were observed in the afternoon, possibly related to melting of the glacier. Most of the ambient noise sequences were located in two vertical clusters, with each cluster potentially corresponding to a crevasse or a moulin. We interpret this ambient noise as being produced by meltwater drainage. In both analyses, we find that inter-station differential arrival times obtained by cross-correlations provide effective information to locate sliding or meltwater drainage processes.

  12. Frequency Dependent Polarization Analysis of Ambient Seismic Noise Recorded at Broadband Seismometers

    Science.gov (United States)

    Koper, K.; Hawley, V.

    2010-12-01

    Analysis of ambient seismic noise is becoming increasingly relevant to modern seismology. Advances in computational speed and storage have made it feasible to analyze years and even decades of continuous seismic data in short amounts of time. Therefore, it is now possible to perform longitudinal studies of station performance in order to identify degradation or mis-installation of seismic equipment. Long-term noise analysis also provides insight into the evolution of the ocean wave climate, specifically whether the frequency and intensity of storms have changed as global temperatures have changed. Here we present a new approach to polarization analysis of seismic noise recorded by three-component seismometers. Essentially, eigen-decomposition of the 3-by-3 Hermitian spectral matrix associated with a sliding window of data is applied to yield various polarization attributes as a function of time and frequency. This in turn yields fundamental information about the composition of seismic noise, such as the extent to which it is polarized, its mode of propagation, and the direction from which it arrives at the seismometer. The polarization attributes can be viewed as function of time or binned over 2D frequency-time space to deduce regularities in the ambient noise that are unbiased by transient signals from earthquakes and explosions. We applied the algorithm to continuous data recorded in 2009 by the seismic station SLM, located in central North America. A rich variety of noise sources was observed. At low frequencies (3 Hz), Rayleigh-type energy was again dominant, in the form of Rg waves created by nearby cultural activities. Analysis of the time dependence of noise power shows that a frequency range of at least 0.02-1.0 Hz (much larger than the microseism band) is sensitive to annual, meteorologically induced sources of noise. We are currently applying our technique to selected seismometers from USArray and the University of Utah Seismic Network.

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

    Science.gov (United States)

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

    2005-12-01

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

  14. 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.

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  16. Vertical line array measurements of ambient noise in the North Pacific.

    Science.gov (United States)

    Farrokhrooz, Mehdi; Wage, Kathleen E; Dzieciuch, Matthew A; Worcester, Peter F

    2017-03-01

    Shipping noise and wind are the dominant sources of ocean noise in the frequency band between 20 and 500 Hz. This paper analyzes noise in that band using data from the SPICEX experiment, which took place in the North Pacific in 2004-2005, and compares the results with other North Pacific experiments. SPICEX included vertical arrays with sensors above and below the surface conjugate depth, facilitating an analysis of the depth dependence of ambient noise. The paper includes several key results. First, the 2004-05 noise levels at 50 Hz measured in SPICEX had not increased relative to levels measured by Morris [(1978). J. Acoust. Soc. Am. 64, 581-590] at a nearby North Pacific site three decades earlier, but rather were comparable to those levels. Second, at 50 Hz the noise below the conjugate depth decreases at a rate of -9.9 dB/km, which is similar to the rate measured by Morris and much less than the rate measured by Gaul, Knobles, Shooter, and Wittenborn [(2007). IEEE J. Ocean. Eng. 32, 497-512] for the CHURCH OPAL experiment. Finally, the paper describes the seasonal trends in noise over the year-long time series of the measurements.

  17. Upper crustal structure of Madeira Island revealed from ambient noise tomography

    Science.gov (United States)

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

    2015-06-01

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

  18. Ocean Basin Impact of Ambient Noise on Marine Mammal Detectability, Distribution, and Acoustic Communication - YIP

    Science.gov (United States)

    2014-09-30

    Detectability, Distribution, and Acoustic Communication - YIP Jennifer L. Miksis-Olds Applied Research Laboratory The Pennsylvania State University...5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Pennsylvania State University,Applied Research Laboratory ,PO...0039 to David Bradley titled “Ambient Noise Analysis from Selected CTBTO Hydroacoustic Sites”. Patterns and trends of ocean sound observed in this

  19. Ambient Noise Tomography Applied to Nodal Data Sets in Induced Seismicity Regions

    Science.gov (United States)

    Sufri, O.; DeShon, H. R.; Ogwari, P.; Hayward, C.; Magnani, M. B.

    2017-12-01

    We present results of ambient noise tomography performed using nodal datasets with different array apertures and geometries deployed in northern Texas and northern Oklahoma to capture induced earthquakes. We show that ambient noise tomography techniques can be performed on small aperture, oddly shaped array datasets. In northern Texas, the nodal data was collected on 10 Hz single-component vertical sensors that were deployed from the collaboration between SMU and Nodal Seismic. The data was acquired between 25 February and 8 March 2014. First, we compute the cross-correlation between the geophone pairs, which are used as Green's functions to perform ambient noise tomography, and find acceptable results between 0.3-1.0 seconds. We compute the phase velocities for these periods and invert the phase velocities to obtain shear wave velocity structure for up to depths of 200 meters underneath the array. The small aperture of the array (2.6 km x 2.92 km) limits depth resolution. The resulting shear wave velocity model is then used as a shallow velocity constraint to improve double-difference local earthquake tomography using the earthquake data from a co-located local seismic network. We present tomography results aimed at resolving 3D velocity heterogeneity associated with the 2013-2015 Azle-Reno induced earthquake sequence. These techniques are also applied to conduct ambient noise tomography in northern Oklahoma using the IRIS Wavefield Community Experiment data. This data was acquired between 23 June and 20 July 2016 from a larger (6 km x 14 km) aperture array consisting of 5 Hz 3-component nodes. Because the aperture of Wavefield network was larger than the north Texas array, we expect to resolve shear velocity to greater depth and provide 3D information on near surface velocity heterogeneity, and possibly resolve faulting associated with earthquakes beneath the array.

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

    Science.gov (United States)

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

    2016-02-01

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

  1. The Effects of Ambient Conditions on Helicopter Rotor Source Noise Modeling

    Science.gov (United States)

    Schmitz, Frederic H.; Greenwood, Eric

    2011-01-01

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

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

    Science.gov (United States)

    Levordashka, Ana; Utz, Sonja

    2016-07-01

    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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  4. 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.

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

    Science.gov (United States)

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

    2017-04-01

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

  6. Design Optimization and Evaluation of Different Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, Hui

    2008-01-01

    With rapid development of wind power technologies and significant growth of wind power capacity installed worldwide, various wind generator systems have been developed and built. The objective of this paper is to evaluate various wind generator systems by optimization designs and comparisons...... and power electronic converter are presented; design optimizations of the investigated wind generator systems are developed with an improved genetic algorithm. Next, the optimization designs are implemented of various wind generator systems at 0.75-MW, 1.5-MW, 3.0-MW, 5.0-MWand 10MW, respectively....... In this paper, seven variable speed constant frequency (VSCF) wind generator systems are investigated, namely permanent magnet synchronous generators with the direct-driven (PMSG_DD), the single-stage gearbox (PMSG_1G) and three-stage gearbox (PMSG_3G) concepts, doubly fed induction generators with the three...

  7. Lightweight MgB2 superconducting 10 MW wind generator

    Science.gov (United States)

    Marino, I.; Pujana, A.; Sarmiento, G.; Sanz, S.; Merino, J. M.; Tropeano, M.; Sun, J.; Canosa, T.

    2016-02-01

    The offshore wind market demands a higher power rate and more reliable turbines in order to optimize capital and operational costs. The state-of-the-art shows that both geared and direct-drive conventional generators are difficult to scale up to 10 MW and beyond due to their huge size and weight. Superconducting direct-drive wind generators are considered a promising solution to achieve lighter weight machines. This work presents an innovative 10 MW 8.1 rpm direct-drive partial superconducting generator using MgB2 wire for the field coils. It has a warm iron rotor configuration with the superconducting coils working at 20 K while the rotor core and the armature are at ambient temperature. A cooling system based on cryocoolers installed in the rotor extracts the heat from the superconducting coils by conduction. The generator's main parameters are compared against a permanent magnet reference machine, showing a significant weight and size reduction. The 10 MW superconducting generator concept will be experimentally validated with a small-scale magnetic machine, which has innovative components such as superconducting coils, modular cryostats and cooling systems, and will have similar size and characteristics as the 10 MW generator.

  8. Integration of wind generation forecasts. Volume 2

    International Nuclear Information System (INIS)

    Ahlstrom, M.; Zavadil, B.; Jones, L.

    2005-01-01

    WindLogics is a company that specializes in atmospheric modelling, visualization and fine-scale forecasting systems for the wind power industry. A background of the organization was presented. The complexities of wind modelling were discussed. Issues concerning location and terrain, shear, diurnal and interannual variability were reviewed. It was suggested that wind power producers should aim to be mainstream, and that variability should be considered as intrinsic to fuel supply. Various utility operating impacts were outlined. Details of an Xcel NSP wind integration study were presented, as well as a studies conducted in New York state and Colorado. It was concluded that regulations and load following impacts with wind energy integration are modest. Overall impacts are dominated by costs incurred to accommodate wind generation variability and uncertainty in the day-ahead time frame. Cost impacts can be reduced with adjustments to operating strategies, improvements in wind forecasting and access to real-time markets. Details of WindLogic's wind energy forecast system were presented, as well as examples of day ahead and hour ahead forecasts and wind speed and power forecasts. Screenshots of control room integration, EMS integration and simulations were presented. Details of a utility-scale wind energy forecasting system funded by Xcel Renewable Development Fund (RDF) were also presented. The goal of the system was to optimize the way that wind forecast information is integrated into the control room environment. Project components were outlined. It was concluded that accurate day-ahead forecasting can lead to significant asset optimization. It was recommended that wind plants share data, and aim to resolve issues concerning grid codes and instrumentation. refs., tabs., figs

  9. 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.

  10. Deriving Deep Ocean Temperature Changes From the Ambient Acoustic Noise Field

    Science.gov (United States)

    Sambell, K.; Evers, L. G.; Snellen, M.

    2016-12-01

    Passively deriving the deep ocean temperature is a challenge. However, knowledge about changes in the deep ocean temperature are important in relation to climate change. In-situ observations are are and satellite observations are hardly applicable. Low-frequency sound waves of a few hertz can penetrate the deep oceans over long distances. As their propagation is temperature dependent, these waves contain valuable information that can be used for temperature monitoring. In this study, the use of interferometry is demonstrated by applying this technique to ambient noise measured at two hydrophone arrays located near Robinson Crusoe Island in the South Pacific Ocean. The arrays are separated by 40 km and are located at a depth of 800 m. Both arrays consist of three hydrophones with an interstation distance of 2 km. It is shown that the acoustic velocity, and with this the temperature variation, can be derived from measured hydro-acoustic data. Furthermore, the findings are supported by ocean models that describe the propagation of sound between the hydrophone arrays. This study shows the potential of using the ambient noise field for temperature monitoring in the deep ocean.

  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. Uppermost mantle and crustal structure at Tristan da Cunha derived from ambient seismic noise

    Science.gov (United States)

    Ryberg, T.; Geissler, W. H.; Jokat, W.; Pandey, S.

    2017-08-01

    According to classical plume theory, the Tristan da Cunha hotspot, located ∼400 km east off the Mid-Atlantic Ridge, is thought to have played a major role in the rifting while creating an aseismic Walvis Ridge during and after the breakup of the South Atlantic margins. Volcanic activity on the Tristan da Cunha Island shows that the hotspot might still be there influencing the upper mantle and crustal structure. In this study we present ambient noise data from 24 broadband OBS around Tristan da Cunha and a seismic station on Nightingale Island, which provide first constraints on the crustal and uppermost mantle structure around the island. By combining ambient noise techniques, dispersion curve analysis of Rayleigh waves, 2D tomographic inversion of travel times and 3D depth inversion of dispersion data we derived a 3D VS velocity model around the archipelago of Tristan da Cunha. The model shows an isolated, vertically sharp bounded thickened and modified crust beneath the islands surrounded by thin oceanic crust (feeding system/magmatic underplating, respectively. The observed simple and localized volcanic structure, embedded in a rather homogeneous crust and upper mantle indicates only minor and very localized magmatic overprinting of the existing lithosphere by the Tristan da Cunha hotspot. The uppermost mantle S wave velocity beneath nearby seamounts and to the SW of the islands is also slow and could indicate a thermal influence from a deeper source, whereas the Tristan da Cunha Fracture Zone shows no signs of modification.

  13. On the effect of topography on short-period ambient noise tomography

    Science.gov (United States)

    Köhler, A.; Weidle, C.; Maupin, V.

    2012-04-01

    Due to the increasing popularity of using empirical Green's functions obtained from ambient seismic noise, more and more regional tomographical studies based on short-periods surface waves are published. Results could potentially be biased in mountainous regions where topography is not small compared to the wavelength and penetration depth of the considered waves. We investigate the effect of topography on the propagation of short-period (3-10 seconds) Rayleigh waves empirically by means of synthetic data using a spectral element code and a 3-D model with real topography. We show that topography along a profile through the studied area can result in an underestimation of phase velocities of up to about 0.7% at the shortest investigated period (3 seconds). Contrary to the expectation that this bias results from the increased surface distance along topography, we find that this error can be estimated by local topographic contrasts in the vicinity of the receiver alone. We discuss and generalize our results by considering topographic profiles through other mountain ranges and find that southern Norway is a good proxy to assess the topography effect. Nevertheless, topographic bias on phase velocity measurements is in general not large enough to produce a significant effect on ambient noise tomographies.

  14. On the effect of topography on surface wave propagation in the ambient noise frequency range

    Science.gov (United States)

    Köhler, Andreas; Weidle, Christian; Maupin, Valérie

    2012-04-01

    Due to the increasing popularity of analyzing empirical Green's functions obtained from ambient seismic noise, more and more regional tomographical studies based on short-period surface waves are published. Results could potentially be biased in mountainous regions where topography is not small compared to the wavelength and penetration depth of the considered waves. We investigate the effect of topography on the propagation of short-period Rayleigh waves empirically by means of synthetic data using a spectral element code and a 3-D model with real topography. We show that topography along a profile through the studied area can result in an underestimation of phase velocities of up to about 0.7% at the shortest investigated period (3 s). Contrary to the expectation that this bias results from the increased surface distance along topography, we find that this error can be estimated by local topographic contrasts in the vicinity of the receiver alone. We discuss and generalize our results by considering topographic profiles through other mountain ranges and find that southern Norway is a good proxy to assess the topography effect. Nevertheless, topographic bias on phase velocity measurements is in general not large enough to significantly affect recovered velocity variations in the ambient noise frequency range.

  15. Potential of ambient seismic noise techniques to monitor the St. Gallen geothermal site (Switzerland)

    Science.gov (United States)

    Obermann, A.; Kraft, T.; Larose, E.; Wiemer, S.

    2015-06-01

    The failures of two recent deep geothermal energy projects in Switzerland (Basel, 2006; St. Gallen, 2013) have again highlighted that one of the key challenges for the successful development and operation of deep underground heat exchangers is to control the risk of inducing potentially hazardous seismic events. In St. Gallen, after an injection test and two acid injections that were accompanied by a small number of micro-earthquakes (MLkick). The "killing" procedures that had to be initiated following standard drilling procedures led to a ML3.5 earthquake. With ambient seismic noise cross correlations from nine stations, we observe a significant loss of waveform coherence that we can horizontally and vertically constrain to the injection location of the fluid. The loss of waveform coherence starts with the onset of the fluid injections 4 days prior to the gas kick. We interpret the loss of coherence as a local perturbation of the medium. We show how ambient seismic noise analysis can be used to assess the aseismic response of the subsurface to geomechanical well operations and how this method could have helped to recognize the unexpected reservoir dynamics at an earlier stage than the microseismic response alone, allowed.

  16. Potential of ambient seismic noise techniques to monitor injection induced subsurface changes

    Science.gov (United States)

    Obermann, A.; Kraft, T.; Wiemer, S.

    2015-12-01

    The failures of two recent deep geothermal energy projects in Switzerland (Basel, 2006; St. Gallen, 2013) have again highlighted that one of the key challenges for the successful development and operation of deep underground heat exchangers is to control the risk of inducing potentially hazardous seismic events. In St. Gallen, after an injection test and two acid injections that were accompanied by a small number of micro-earthquakes (ML kick). The "killing" procedures that had to be initiated following standard drilling procedures led to a ML3.5 earthquake. With ambient seismic noise cross correlations from nine stations, we observe a significant loss of waveform coherence that we can horizontally and vertically constrain to the injection location of the fluid. The loss of waveform coherence starts with the onset of the fluid injections 4 days prior to the gas kick. We interpret the loss of coherence as a local perturbation of the medium. We show how ambient seismic noise analysis can be used to assess the aseismic response of the subsurface to geomechanical well operations and how this method could have helped to recognize the unexpected reservoir dynamics at an earlier stage than the microseismic response alone, allowed.

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

    Science.gov (United States)

    Powell, Jason; Chesky, Kris

    2017-09-01

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

  18. Ambient noise as the new source for urban engineering seismology and earthquake engineering: a case study from Beijing metropolitan area

    Science.gov (United States)

    Liu, Lanbo; Chen, Qi-fu; Wang, Weijun; Rohrbach, Eric

    2014-02-01

    In highly populated urban centers, traditional seismic survey sources can no longer be properly applied due to restrictions in modern civilian life styles. The ambient vibration noise, including both microseisms and microtremor, though are generally weak but available anywhere and anytime, can be an ideal supplementary source for conducting seismic surveys for engineering seismology and earthquake engineering. This is fundamentally supported by advanced digital signal processing techniques for effectively extracting the useful information out from the noise. Thus, it can be essentially regarded as a passive seismic method. In this paper we first make a brief survey of the ambient vibration noise, followed by a quick summary of digital signal processing for passive seismic surveys. Then the applications of ambient noise in engineering seismology and earthquake engineering for urban settings are illustrated with examples from Beijing metropolitan area. For engineering seismology the example is the assessment of site effect in a large area via microtremor observations. For earthquake engineering the example is for structural characterization of a typical reinforced concrete high-rise building using background vibration noise. By showing these examples we argue that the ambient noise can be treated as a new source that is economical, practical, and particularly valuable to engineering seismology and earthquake engineering projects for seismic hazard mitigation in urban areas.

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

    Science.gov (United States)

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

    2017-12-01

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

  20. Retrieval of Body-Wave Reflections Using Ambient Noise Interferometry Using a Small-Scale Experiment

    Science.gov (United States)

    Dantas, Odmaksuel Anísio Bezerra; do Nascimento, Aderson Farias; Schimmel, Martin

    2018-02-01

    We report the retrieval of body-wave reflections from noise records using a small-scale experiment over a mature oil field. The reflections are obtained by cross-correlation and stacking of the data. We used the stacked correlograms to create virtual source-to-receiver common shot gathers and are able to obtain body-wave reflections. Surface waves that obliterate the body-waves in our noise correlations were attenuated following a standard procedure from active source seismics. Further different strategies were employed to cross-correlate and stack the data: classical geometrical normalized cross-correlation (CCGN), phase cross-correlation (PCC), linear stacking**** and phase weighted stacking (PWS). PCC and PWS are based on the instantaneous phase coherence of analytic signals. The four approaches are independent and reveal the reflections; nevertheless, the combination of PWS and CCGN provided the best results. Our analysis is based on 2145 cross-correlations of 600 s data segments. We also compare the resulted virtual shot gathers with an active 2D seismic line near the passive experiment. It is shown that our ambient noise analysis reproduces reflections which are present in the active seismic data.

  1. 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

  2. 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

  3. Association between ambient noise exposure, hearing acuity, and risk of acute occupational injury.

    Science.gov (United States)

    Cantley, Linda F; Galusha, Deron; Cullen, Mark R; Dixon-Ernst, Christine; Rabinowitz, Peter M; Neitzel, Richard L

    2015-01-01

    This study aimed to examine the associations between acute workplace injury risk, ambient noise exposure, and hearing acuity, adjusting for reported hearing protection use. In a cohort of 9220 aluminum manufacturing workers studied over six years (33 300 person-years, 13 323 person-jobs), multivariate mixed effects models were used to estimate relative risk (RR) of all injuries as well as serious injuries by noise exposure category and hearing threshold level (HTL) adjusting for recognized and potential confounders. Compared to noise exposure was associated with elevated risk in a monotonic and statistically significant exposure-response pattern for all injuries and serious injuries with higher risk estimates observed for serious injuries [82-84.99 dBA: RR 1.26, 95% confidence interval (95% CI) 0.96-1.64; 85-87.99 dBA: RR 1.39, 95% CI 1.05-1.85; ≥88 dBA: RR 2.29, 95% CI 1.52-3.47]. Hearing loss was associated with increased risk for all injuries, but was not a significant predictor of risk for the subset of more serious injuries. Compared to those without hearing loss, workers with HTL ≥25 dB had 21% increased all injury risk (RR 1.21, 95% CI 1.09-1.33) while those with HTL 10-24.99 dB had 6% increased risk (RR 1.06, 95% CI 1.00-1.13). Reported hearing protection type did not predict injury risk. Noise exposure levels as low as 85 dBA may increase workplace injury risk. HTL was associated with increased risk for all, but not the subset of serious, injuries. Additional study is needed both to confirm the observed associations and explore causal pathways.

  4. 3D shear wave velocity structure revealed with ambient noise tomography on a DAS array

    Science.gov (United States)

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

    2017-12-01

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

  5. Alternative methods of modeling wind generation using production costing models

    International Nuclear Information System (INIS)

    Milligan, M.R.; Pang, C.K.

    1996-08-01

    This paper examines the methods of incorporating wind generation in two production costing models: one is a load duration curve (LDC) based model and the other is a chronological-based model. These two models were used to evaluate the impacts of wind generation on two utility systems using actual collected wind data at two locations with high potential for wind generation. The results are sensitive to the selected wind data and the level of benefits of wind generation is sensitive to the load forecast. The total production cost over a year obtained by the chronological approach does not differ significantly from that of the LDC approach, though the chronological commitment of units is more realistic and more accurate. Chronological models provide the capability of answering important questions about wind resources which are difficult or impossible to address with LDC models

  6. Magmatism on rift flanks: Insights from ambient noise phase velocity in Afar region

    Science.gov (United States)

    Korostelev, Félicie; Weemstra, Cornelis; Leroy, Sylvie; Boschi, Lapo; Keir, Derek; Ren, Yong; Molinari, Irene; Ahmed, Abdulhakim; Stuart, Graham W.; Rolandone, Frédérique; Khanbari, Khaled; Hammond, James O. S.; Kendall, J. M.; Doubre, Cécile; Ganad, Ismail Al; Goitom, Berhe; Ayele, Atalay

    2015-04-01

    During the breakup of continents in magmatic settings, the extension of the rift valley is commonly assumed to initially occur by border faulting and progressively migrate in space and time toward the spreading axis. Magmatic processes near the rift flanks are commonly ignored. We present phase velocity maps of the crust and uppermost mantle of the conjugate margins of the southern Red Sea (Afar and Yemen) using ambient noise tomography to constrain crustal modification during breakup. Our images show that the low seismic velocities characterize not only the upper crust beneath the axial volcanic systems but also both upper and lower crust beneath the rift flanks where ongoing volcanism and hydrothermal activity occur at the surface. Magmatic modification of the crust beneath rift flanks likely occurs for a protracted period of time during the breakup process and may persist through to early seafloor spreading.

  7. 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

  8. Rayleigh wave tomography of the British Isles from ambient seismic noise

    Science.gov (United States)

    Nicolson, Heather; Curtis, Andrew; Baptie, Brian

    2014-08-01

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

  9. 3D basin structure of the Santa Clara Valley constrained by ambient noise tomography

    Science.gov (United States)

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

    2017-12-01

    The basin structure is an important factor controls the intensity and duration of ground shaking due to earthquake. Thus it is important to study the basin structure for better understanding seismic hazard and also improving the earthquake preparedness. An active source seismic survey is the most appropriate method to determine the basin structure in detail but its applicability, especially in urban areas, is limited. In this study, we tested the potential of an ambient noise tomography, which can be a cheaper and more easily applicable method compared to a traditional active source survey, to construct the velocity model of the basin. Our testing region is the Santa Clara Valley, which is one of the major urban sedimentary basins in the States. We selected this region because continuous seismic recordings and well defined velocity models are available. Continuous seismic recordings of 6 months from short-period array of Santa Clara Valley Seismic Experiment are cross-correlated with 1 hour time window. And the fast marching method and the subspace method are jointly applied to construct 2-D group velocity maps between 0.2 - 4.0 Hz. Then, shear wave velocity model of the Santa Clara Valley is calculated up to 5 km depth using bayesian inversion technique. Although our model cannot depict the detailed structures, it is roughly comparable with the velocity model of the US Geological Survey, which is constrained by active seismic surveys and field researches. This result indicate that an ambient noise tomography can be a replacement, at least in part, of an active seismic survey to construct the velocity model of the basin.

  10. 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.

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

    Science.gov (United States)

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

    2017-12-01

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

  12. 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.

  13. 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.

  14. 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.

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

    Science.gov (United States)

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

    2017-12-01

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

  16. Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise.

    Science.gov (United States)

    Chaves, Esteban J; Schwartz, Susan Y

    2016-01-01

    In subduction zones, elevated pore fluid pressure, generally linked to metamorphic dehydration reactions, has a profound influence on the mechanical behavior of the plate interface and forearc crust through its control on effective stress. We use seismic noise-based monitoring to characterize seismic velocity variations following the 2012 Nicoya Peninsula, Costa Rica earthquake [M w (moment magnitude) 7.6] that we attribute to the presence of pressurized pore fluids. Our study reveals a strong velocity reduction (~0.6%) in a region where previous work identified high forearc pore fluid pressure. The depth of this velocity reduction is constrained to be below 5 km and therefore not the result of near-surface damage due to strong ground motions; rather, we posit that it is caused by fracturing of the fluid-pressurized weakened crust due to dynamic stresses. Although pressurized fluids have been implicated in causing coseismic velocity reductions beneath the Japanese volcanic arc, this is the first report of a similar phenomenon in a subduction zone setting. It demonstrates the potential to identify pressurized fluids in subduction zones using temporal variations of seismic velocity inferred from ambient seismic noise correlations.

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

    KAUST Repository

    Wang, Yadong

    2017-05-08

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

  18. 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

  19. Analysis of ambient noise in Yalova, Turkey: discrimination between artificial and natural excitations

    Science.gov (United States)

    Yalcinkaya, Esref; Tekebas, Serhat; Pinar, Ali

    2013-07-01

    Ambient noise measurements acquired in Yalova, which was highly damaged during the 1999 Izmit earthquake, are analyzed to explore the site characteristics. The region of Yalova is governed by complex geological and geomorphological structures consisting of river beds extending from the mountains to the sea, ridges between them, plains in front of them with different size, and the sea coast. As a result of these shallow geological features, the H/V curves exhibit complex patterns. Clear peaks in the H/V curves, which can be interpreted as reliable site resonance frequency, are observed only at about half of the measurement sites. At the remaining sites industrial peaks, broad peaks, or flat responses dominate the spectral ratio graphs. We observed that man-made noises generated by marble cutting machines in Hersek delta mask the site resonance frequencies or can be misinterpreted as a resonance frequency. In total, we identified three anthropogenic noise sources at fundamental frequencies of 1.3, 1.5, and 1.7 Hz along with their two- and threefold harmonics. The parts of H/V curves showing unusual low scattering can be a clue to identify anthropogenic effects. In the assessment of H/V curves, the site location and the similarity of the near surface geology were taken into account. The Laledere plain with thick and soft sediment sequence surprisingly displays flat responses due to a possible low impedance contrast. The Ciftlikkoy and Hacimehmet plains exhibit clear resonance peaks at nearly 1 Hz possessing the largest amplitudes. These sites experienced the highest damage in Yalova during the Izmit earthquake. In contrast, the Cinarcik region which was also exposed to high damage, do not show any obvious amplifications on the H/V curves. Generally, the H/V curves for valley and ridge sites in Yalova reveals a resonance peak at approximately 1 Hz and almost flat curves, respectively. However, several sites on the ridges and valleys portray different patterns.

  20. Ambient noise tomography of Ecuador: Fore- and back-arc velocity structure and radial anisotropy

    Science.gov (United States)

    Lynner, C.; Beck, S. L.; Porritt, R.; Meltzer, A.; Alvarado, A. P.; Gabriela, P.; Ruiz, M. C.; Hoskins, M.; Stachnik, J.; Rietbrock, A.; Leon-Rios, S.; Regnier, M. M.; Agurto-Detzel, H.; Font, Y.; Charvis, P.

    2017-12-01

    In northern South America, the oceanic Nazca plate subducts beneath the South American continent, giving rise to the high mountains of the northern Andes. The Ecuador subduction zone has a history of large megathrust earthquakes, most recently the Mw=7.8 April 16, 2016, Pedernales earthquake. The volcanic arc in Ecuador is broad with active volcanoes along both the western and eastern cordilleras. Many of these volcanoes surround the city of Quito putting millions of people at risk. A recent international broadband aftershock deployment was conducted for approximately one year after the Pedernales mainshock and this data combined with a sub-set of data from from the permanent IGEPN national network provide an ideal data set to use for ambient noise tomography (ANT) to constrain absolute Vsh and Vsv across Ecuador. ANT studies use noise-generated surface wave dispersion measurements to invert for 3D shear velocity in the crust. Having a precise understanding of crustal velocity structure is necessary to advance a number of projects, including better earthquake locations of the April 16, 2016 Pedernales-earthquake aftershock sequence and identifying large-scale partial melt zones associated with the active volcanic arc. The majority of ANT studies use only Rayleigh waves to constrain Vsv structure. Initial Rayleigh wave ANT results, using periods between 8 and 40 seconds, show a fast phase velocities for the forearc and much slower phase velocities for the high elevation volcanic arc. Including Love wave dispersion measurements can improve overall crustal velocity models, as well as provide constraints on radial anisotropy. Radial anisotropy can develop in a variety of ways but most typically arises from the deformation-induced alignment of anisotropic minerals. Radial anisotropy, therefore, can inform on patterns of ductile crustal flow. Strong radial anisotropy at mid-crustal depths from ANT has already been observed south of Ecuador, in the Central Andean Plateau

  1. Ambient noise causes independent changes in distinct spectro-temporal features of echolocation calls in horseshoe bats.

    Science.gov (United States)

    Hage, Steffen R; Jiang, Tinglei; Berquist, Sean W; Feng, Jiang; Metzner, Walter

    2014-07-15

    One of the most efficient mechanisms to optimize signal-to-noise ratios is the Lombard effect - an involuntary rise in call amplitude due to ambient noise. It is often accompanied by changes in the spectro-temporal composition of calls. We examined the effects of broadband-filtered noise on the spectro-temporal composition of horseshoe bat echolocation calls, which consist of a constant-frequency component and initial and terminal frequency-modulated components. We found that the frequency-modulated components became larger for almost all noise conditions, whereas the bandwidth of the constant-frequency component increased only when broadband-filtered noise was centered on or above the calls' dominant or fundamental frequency. This indicates that ambient noise independently modifies the associated acoustic parameters of the Lombard effect, such as spectro-temporal features, and could significantly affect the bat's ability to detect and locate targets. Our findings may be of significance in evaluating the impact of environmental noise on echolocation behavior in bats. © 2014. Published by The Company of Biologists Ltd.

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  3. Directionality analysis and Rayleigh wave tomography of ambient seismic noise in southern Norway

    Science.gov (United States)

    Köhler, Andreas; Weidle, Christian; Maupin, Valérie

    2011-01-01

    We process seismic broad-band data from southern Norway by cross correlation of ambient seismic noise in view of getting a better image of the crustal structure in the area. The main data set sterns from the temporary MAGNUS network which operated continuously from 2006 September to 2008 June. Additionally, data from permanent stations of the National Norwegian Seismic Network, the NORSAR array and GSN stations in the region are used. We compute vertical component cross-correlation functions using 41 receivers for 3-month time windows. Evaluation of the azimuthal and temporal variation of signal-to-noise ratios (SNRs) and f-k analysis of data from NORSAR array between 3 and 25 s period shows that the dominant source areas of seismic noise are located to the west and north of the network during most of the measurement time, which corresponds well to the Norwegian coast line. During summer months, the SNRs decrease but the azimuthal distribution becomes more uniform between 7 and 12 s period, suggesting a more diffuse character of the wavefield. Primary ocean microseisms above 12 s show different dominant source azimuths during this time period compared to the winter months. Time-frequency analysis is applied to measure Rayleigh wave group velocity dispersion curves between each station pair for each 3-month correlation stack and the mean and variance of all dispersion curves is computed for each path. After rejection of low-quality data, a careful analysis shows that the group velocities are not biased by noise directionality. We invert the data for group velocity maps at period bands between 3 and 25 s. At short periods, we find an average Rayleigh wave group speed of about 3 km s-1 and velocity anomalies that correlate very well with local surface geology. While higher velocities (+5 per cent) can be associated with the Caledonian nappes in the central part of southern Norway, the Oslo Graben is reflected by negative velocity anomalies (-3 to -5 per cent). At

  4. Market protocols in ERCOT and their effect on wind generation

    International Nuclear Information System (INIS)

    Sioshansi, Ramteen; Hurlbut, David

    2010-01-01

    Integrating wind generation into power systems and wholesale electricity markets presents unique challenges due to the characteristics of wind power, including its limited dispatchability, variability in generation, difficulty in forecasting resource availability, and the geographic location of wind resources. Texas has had to deal with many of these issues beginning in 2002 when it restructured its electricity industry and introduced aggressive renewable portfolio standards that helped spur major investments in wind generation. In this paper we discuss the issues that have arisen in designing market protocols that take account of these special characteristics of wind generation and survey the regulatory and market rules that have been developed in Texas. We discuss the perverse incentives some of the rules gave wind generators to overschedule generation in order to receive balancing energy payments, and steps that have been taken to mitigate those incentive effects. Finally, we discuss more recent steps taken by the market operator and regulators to ensure transmission capacity is available for new wind generators that are expected to come online in the future. (author)

  5. Maximal Ambient Noise Levels and Type of Voice Material Required for Valid Use of Smartphones in Clinical Voice Research.

    Science.gov (United States)

    Lebacq, Jean; Schoentgen, Jean; Cantarella, Giovanna; Bruss, Franz Thomas; Manfredi, Claudia; DeJonckere, Philippe

    2017-09-01

    Smartphone technology provides new opportunities for recording standardized voice samples of patients and transmitting the audio files to the voice laboratory. This drastically improves the achievement of baseline designs, used in research on efficiency of voice treatments. However, the basic requirement is the suitability of smartphones for recording and digitizing pathologic voices (mainly characterized by period perturbations and noise) without significant distortion. In a previous article, this was tested using realistic synthesized deviant voice samples (/a:/) with three precisely known levels of jitter and of noise in all combinations. High correlations were found between jitter and noise to harmonics ratio measured in (1) recordings via smartphones, (2) direct microphone recordings, and (3) sound files generated by the synthesizer. In the present work, similar experiments were performed (1) in the presence of increasing levels of ambient noise and (2) using synthetic deviant voice samples (/a:/) as well as synthetic voice material simulating a deviant short voiced utterance (/aiuaiuaiu/). Ambient noise levels up to 50 dB A are acceptable. However, signal processing occurs in some smartphones, and this significantly affects estimates of jitter and noise to harmonics ratio when formant changes are introduced in analogy with running speech. The conclusion is that voice material must provisionally be limited to a sustained /a/. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  6. Crustal thickness across the Trans-European Suture Zone from ambient noise autocorrelations

    Science.gov (United States)

    Becker, G.; Knapmeyer-Endrun, B.

    2018-02-01

    We derive autocorrelations from ambient seismic noise to image the reflectivity of the subsurface and to extract the Moho depth beneath the stations for two different data sets in Central Europe. The autocorrelations are calculated by smoothing the spectrum of the data in order to suppress high amplitude, narrow-band signals of industrial origin, applying a phase autocorrelation algorithm and time-frequency domain phase-weighted stacking. The stacked autocorrelation results are filtered and analysed predominantly in the frequency range of 1-2 Hz. Moho depth is automatically picked inside uncertainty windows obtained from prior information. The processing scheme we developed is applied to data from permanent seismic stations located in different geological provinces across Europe, with varying Moho depths between 25 and 50 km, and to the mainly short period temporary PASSEQ stations along seismic profile POLONAISE P4. The autocorrelation results are spatially and temporarily stable, but show a clear correlation with the existence of cultural noise. On average, a minimum of six months of data is needed to obtain stable results. The obtained Moho depth results are in good agreement with the subsurface model provided by seismic profiling, receiver function estimates and the European Moho depth map. In addition to extracting the Moho depth, it is possible to identify an intracrustal layer along the profile, again closely matching the seismic model. For more than half of the broad-band stations, another change in reflectivity within the mantle is observed and can be correlated with the lithosphere-asthenosphere boundary to the west and a mid-lithospheric discontinuity beneath the East European Craton. With the application of the developed autocorrelation processing scheme to different stations with varying crustal thicknesses, it is shown that Moho depth can be extracted independent of subsurface structure, when station coverage is low, when no strong seismic sources are

  7. A seismic waves velocity model for Gran Canaria Island from ambient noise correlations

    Science.gov (United States)

    García-Jerez, Antonio; Almendros, Javier; Martínez-Arévalo, Carmen; de Lis Mancilla, Flor; Luzón, Francisco; Carmona, Enrique; Martín, Rosa; Sánchez, Nieves

    2014-05-01

    We have analysed continuous ambient seismic noise recorded by a temporary array in Gran Canaria (Canary Islands, Spain) in order to find a velocity model for the top few kilometers. The SISTEVOTENCAN-IGN seismic array consisted of five broadband stations surrounding a sixth central one placed close to Pico de las Nieves, at the center of the island. The array had a radius of 12-14 km, with interstation distances ranging from 10 to 27 km. This network was operative from December 2009 to November 2011. The Green's functions between the 15 pairs of stations have been estimated in the time domain by stacking cross-correlations of 60-s time windows for the whole recording period (~2 years). The effects of several processing adjustments such as 1-bit normalization and spectral whitening are discussed. We observe significant differences (mainly in amplitude) between causal and acausal parts of the estimated Green's functions, which can be associated to an uneven distribution of the seismic noise sources. The application of a phase-matched filter based on an average dispersion curve allowed the effective reduction of some spurious early arrivals and the selection of fundamental-mode Rayleigh wave pulses, making possible an automatic extraction of their group velocities. Then, Rayleigh-wave dispersion curves were retrieved for the set of paths by using frequency-time analysis (FTAN) as well as by following the procedure described by Herrin and Goforth (1977, BSSA) based on the iterative fitting of a phase-matched filter which optimally undisperses the signal. Reliable curves were obtained from 1 s to 6-7 s with group velocities ranging between 1.5 and 2.2 km/s. Some lateral variations in velocity have been detected in spite of the limited spatial coverage and path density, which substantially restricted the resolution. A mean S-wave velocity model has been inverted for this area down to ~3 km.

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

    Science.gov (United States)

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

    2017-12-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

  10. Investigation of surge protective devices operation of a wind generator

    International Nuclear Information System (INIS)

    Dimitrov, D.; Vasileva, M.

    2008-01-01

    The interest to the investments in a wind energetics increases in the last years. The wind energetics is the fastest developing direction in the energetics in global scale. The wind energy is more attractive because its prices are lower in comparison of the other technologies for generating energy. The right choice of the surge protective devices has the important meaning on building and exploitation of the wind generators. The aim of this paper is investigation of the surge protective devices operation when they are installation to a wind generator. (authors)

  11. Environmental Impact Assessment of Wind Generators in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Vladimír Lapčík

    2008-11-01

    Full Text Available The article summarizes author´s experience with environmental impact assessment in branch of wind generators. The introductorypart of paper describes legislative obligations of the Czech Republic in frame of fulfilling the European Union´s limits in branch ofrenewable energy resources utilization. Next part of paper deals with analysis of impacts of wind generators on the environment.The final part of paper deals with experience with implementation of the environmental impact assessment process (pursuant to the ActNo. 100/2001 Coll. in the field of wind power in the Czech Republic.

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

    Science.gov (United States)

    Bao, X.; Song, X.

    2017-12-01

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  14. Environmental seismology: What can we learn on earth surface processes with ambient noise?

    Science.gov (United States)

    Larose, Eric; Carrière, Simon; Voisin, Christophe; Bottelin, Pierre; Baillet, Laurent; Guéguen, Philippe; Walter, Fabian; Jongmans, Denis; Guillier, Bertrand; Garambois, Stéphane; Gimbert, Florent; Massey, Chris

    2015-05-01

    Environmental seismology consists in studying the mechanical vibrations that originate from, or that have been affected by external causes, that is to say causes outside the solid Earth. This includes for instance the coupling between the solid Earth and the cryosphere, or the hydrosphere, the anthroposphere and the specific sources of vibration developing there. Environmental seismology also addresses the modifications of the wave propagation due to environmental forcing such as temperature and hydrology. Recent developments in data processing, together with increasing computational power and sensor concentration have led to original observations that allow for the development of this new field of seismology. In this article, we will particularly review how we can track and interpret tiny changes in the subsurface of the Earth related to external changes from modifications of the seismic wave propagation, with application to geomechanics, hydrology, and natural hazard. We will particularly demonstrate that, using ambient noise, we can track 1) thermal variations in the subsoil, in buildings or in rock columns; 2) the temporal and spatial evolution of a water table; 3) the evolution of the rigidity of the soil constituting a landslide, and especially the drop of rigidity preceding a failure event.

  15. Magmatism on rift flanks: insights from Ambient-Noise Phase-velocity in Afar region

    Science.gov (United States)

    Korostelev, Félicie; Weemstra, Cornelis; Leroy, Sylvie; Boschi, Lapo; Ren, Yong; Ahmed, Abdulhakim; Keir, Derek; Stuart, Graham W.; Rolandone, Frédérique; Khanbari, Khaled; Hammond, James O. S.; Kendall, J. Michael; Doubre, Cécile; Ganad, Ismail Al

    2015-04-01

    During the breakup of continent in the presence of magma, strain is commonly assumed to initially occur by border faulting, and progressively migrate in space and time towards axial magma intrusion. Magmatic processes near the rift flanks are commonly ignored. We present phase-velocity maps of the crust and uppermost mantle of the conjugate margins of the southern Red Sea (Afar and Yemen) using ambient noise tomography to constrain crustal modification during breakup. Our images show that the low seismic velocities characterize not only upper crust beneath the axial volcanic systems, but also both upper and lower crust beneath rift flanks where ongoing volcanism and hydrothermal activity occurs at the surface. The results show that magmatic modification of the crust beneath rift flanks likely occurs for a protracted period of time during the breakup process, and may persist through to early seafloor spreading. Since ongoing flank magmatism during breakup impacts the thermal evolution of the lithosphere, it has implications for the subsidence history of the rift.

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

    International Nuclear Information System (INIS)

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

    2009-03-01

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

  17. The crustal structure beneath The Netherlands derived from ambient seismic noise

    Science.gov (United States)

    Yudistira, Tedi; Paulssen, Hanneke; Trampert, Jeannot

    2017-11-01

    This work presents the first comprehensive 3-D model of the crust beneath The Netherlands. To obtain this model, we designed the NARS-Netherlands project, a dense deployment of broadband stations in the area. Rayleigh and Love wave group velocity dispersion was measured from ambient noise cross-correlations. Azimuthally anisotropic group velocity maps were then constructed and the isotropic part was used to determine a shear wave speed model that includes the effects of radial anisotropy. Employing the Neighbourhood Algorithm for the depth inversion, we obtained probabilistic estimates of the radially anisotropic model parameters. We found that the variations in the thickness of the top layer largely match the transition from sediments of Permian age to those of Carboniferous age. Regions of high faulting density such as the West Netherlands Basin and Roer Valley Graben are recognized in our model by their negative radial anisotropy (VSH - VSV Love wave group velocity data at periods of around 20 s show evidence for azimuthal anisotropy with a NW-SE fast direction. This anisotropy is likely related to NW-SE rock fabric in the lower crust thought to originate from the Caledonian deformation.

  18. Crustal Structure of the Gulf of Aden Continental Margins, from Afar to Oman, by Ambient Noise Seismic Tomography

    Science.gov (United States)

    Korostelev, F.; Weemstra, C.; Boschi, L.; Leroy, S. D.; Ren, Y.; Stuart, G. W.; Keir, D.; Rolandone, F.; Ahmed, A.; Al Ganad, I.; Khanbari, K. M.; Doubre, C.; Hammond, J. O. S.; Kendall, J. M.

    2014-12-01

    Continental rupture processes under mantle plume influence are still poorly known although extensively studied. The Gulf of Aden presents volcanic margins to the west, where they are influenced by the Afar hotspot, and non volcanic margins east of longitude 46° E. We imaged the crustal structure of the Gulf of Aden continental margins from Afar to Oman to evaluate the role of the Afar plume on the evolution of the passive margin and its extent towards the East. We use Ambient Noise Seismic Tomography to better understand the architecture and processes along the Gulf of Aden. This recent method, developed in the last decade, allows us to study the seismic signal propagating between two seismic stations. Ambient Noise Seismic Tomography is thus free from artifacts related to the distribution of earthquakes. We collected continuous records from about 200 permanent or temporary stations since 1999 to compute Rayleigh phase velocity maps over the Gulf of Aden.

  19. High Power Wind Generator Designs with Less or No PMs

    DEFF Research Database (Denmark)

    Boldea, Ion; Tutelea, Lucian; Blaabjerg, Frede

    2014-01-01

    The recent steep increase in high energy permanent magnet (PM) price (above 130$/kg and more) triggered already strong R&D efforts to develop wind generators with less PMs (less weight in NdFeB magnets/kW or the use of ferrite PMs) or fully without PMs. All these by optimizing existing dc excited...

  20. Phase spectral composition of wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    A study of the composition of the phase spectra of wind generated ocean surface waves is carried out using wave records collected employing a ship borne wave recorder. It is found that the raw phase spectral estimates could be fitted by the Uniform...

  1. Interpretation of nonlinearity in wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    This study attempts to resolve a mix-up between a physical process and its mathematical interpretation in the context of wind waves on ocean surface. Wind generated wave systems, are conventionally interpreted as a result of interaction of a number...

  2. Study of site effect using mining induced seismic events and ambient noise from Karviná region

    Czech Academy of Sciences Publication Activity Database

    Kaláb, Zdeněk; Lyubushin, A. A.

    2008-01-01

    Roč. 5, č. 2 (2008), s. 105-113 ISSN 1214-9705. [Polish-Czech-Slovakian Symposium on Mining and Environmental Geophysics/31./. Janov nad Nisou, 24.09.2007-27.09.2007] R&D Projects: GA ČR GA105/07/0878 Institutional research plan: CEZ:AV0Z30860518 Keywords : mining induced seismic event * ambient noise * frequency analysis Subject RIV: DC - Siesmology, Volcanology, Earth Structure http://www.irsm.cas.cz

  3. Seismic site characterization of the Kastelli (Kissamos) Basin in northwest Crete (Greece): Assessments using ambient noise recordings

    OpenAIRE

    Moisidi, M; Vallianatos, F; Kershaw, S; Collins, P

    2015-01-01

    Crete is actively seismic and site response studies are needed for estimating local site conditions subjected to seismic activity. In order to collect basic data, we performed ambient noise recordings to estimate the site response of the surface and near subsurface structure of the small-scale Kastelli Basin in northwest Crete. The spatial horizontal to vertical spectral ratios (HVSR) resonance pattern of the investigated sites in the centre of the Basin consists of either one or two peaks di...

  4. 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

  5. The Plumbing System Feeding the Lusi Eruption Revealed by Ambient Noise Tomography

    Science.gov (United States)

    Fallahi, Mohammad Javad; Obermann, Anne; Lupi, Matteo; Karyono, Karyono; Mazzini, Adriano

    2017-10-01

    Lusi is a sediment-hosted hydrothermal system featuring clastic-dominated geyser-like eruption behavior in East Java, Indonesia. We use 10 months of ambient seismic noise cross correlations from 30 temporary seismic stations to obtain a 3-D model of shear wave velocity anomalies beneath Lusi, the neighboring Arjuno-Welirang volcanic complex, and the Watukosek fault system connecting the two. Our work reveals a hydrothermal plume, rooted at a minimum 6 km depth that reaches the surface at the Lusi site. Furthermore, the inversion shows that this vertical anomaly is connected to the adjacent volcanic complex through a narrow ( 3 km wide) low velocity corridor slicing the survey area at a depth of 4-6 km. The NE-SW direction of this elongated zone matches the strike of the Watukosek fault system. Distinct magmatic chambers are also inferred below the active volcanoes. The large-scale tomography features an exceptional example of a subsurface connection between a volcanic complex and a solitary erupting hydrothermal system hosted in a hydrocarbon-rich back-arc sedimentary basin. These results are consistent with a scenario where deep-seated fluids (e.g., magmas and released hydrothermal fluids) flow along a region of enhanced transmissivity (i.e., the Watukosek fault system damage zone) from the volcanic arc toward the back arc basin where Lusi resides. The triggered metamorphic reactions occurring at depth in the organic-rich sediments generated significant overpressure and fluid upwelling that is today released at the spectacular Lusi eruption site.

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

    Science.gov (United States)

    Gaebler, Peter J.; Ceranna, Lars

    2016-04-01

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

  7. Crustal Seismic Vs and Vs anisotropy of Northeast Japan Revealed by Ambient Noise Tomography

    Science.gov (United States)

    Chen, K. X.; Gung, Y.; Kuo, B. Y.; Huang, T. Y.

    2017-12-01

    We present 3D crustal models of Vs and Vs azimuthal anisotropy of the Tohoku region, Japan. We employ the Welch's method to derive the empirical Green's functions (EGF) of Rayleigh waves from one year of continuous records of 123 short-period stations of the dense high-sensitivity seismograph network (Hi-net). We compute EGFs for about 4000 station pairs with interstation distance less than 300 km. For each qualified EGF, we measure the dispersion in the period range from 3 to 16 seconds. We then construct the models by using a wavelet-based multi-scale inversion technique. In the resulting models, characteristics of Vs variations and Vs azimuthal anisotropy are closely related to surface geology, Quaternary volcano activities, and plate motions. For the Vs variations in the shallow crust (well correlated to the volcano belt. For the Vs anisotropy, the strength and the patterns of fast polarization directions (FPD) are depth-dependent. In the shallow crust, the anisotropy is strong, and are dominated by the typical orogeny parallel anisotropy, with FPDs parallel to the main strikes of the mountain range. While in the lower crust, the FPDs are generally parallel to the absolute plate motion. Interestingly, the distribution of PFDs is rather chaotic and strength of anisotropy is weak in the middle crust ( 8 - 20 km). We propose that the weak and random anisotropy in this layer is likely related to the presence of magma reservoirs beneath the volcano belt, as the associated active volcanism may cause the destruction of the alignment of crustal fabrics Key words: Tohoku, ambient noise, seismic anisotropy, surface wave tomography, volcano activities

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

    Science.gov (United States)

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

    2013-12-01

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

  9. Variability in ambient noise levels and call parameters of North Atlantic right whales in three habitat areas.

    Science.gov (United States)

    Parks, Susan E; Urazghildiiev, Ildar; Clark, Christopher W

    2009-02-01

    The North Atlantic right whale inhabits the coastal waters off the east coasts of the United States and Canada, areas characterized by high levels of shipping and fishing activities. Acoustic communication plays an important role in the social behavior of these whales and increases in low-frequency noise may be leading to changes in their calling behavior. This study characterizes the ambient noise levels, including both natural and anthropogenic sources, and right whale upcall parameters in three right whale habitat areas. Continuous recordings were made seasonally using autonomous bottom-mounted recorders in the Bay of Fundy, Canada (2004, 2005), Cape Cod Bay, (2005, 2006), and off the coast of Georgia (2004-2005, 2006-2007). Consistent interannual trends in noise parameters were found for each habitat area, with both the band level and spectrum level measurements higher in the Bay of Fundy than in the other areas. Measured call parameters varied between habitats and between years within the same habitat area, indicating that habitat area and noise levels alone are not sufficient to predict variability in call parameters. These results suggest that right whales may be responding to the peak frequency of noise, rather than the absolute noise level in their environment.

  10. 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.

  11. Renewable energy and sustainable communities: Alaska's wind generator experience.

    Science.gov (United States)

    Konkel, R Steven

    2013-01-01

    In 1984, the Alaska Department of Commerce and Economic Development (DCED) issued the State's first inventory/economic assessment of wind generators, documenting installed wind generator capacity and the economics of replacing diesel-fuel-generated electricity. Alaska's wind generation capacity had grown from hundreds of installed kilowatts to over 15.3 megawatts (MW) by January 2012. This article reviews data and conclusions presented in "Alaska's Wind Energy Systems; Inventory and Economic Assessment" (1). (Alaska Department of Commerce and Economic Development, S. Konkel, 1984). It provides a foundation and baseline for understanding the development of this renewable energy source. Today's technologies have evolved at an astonishing pace; a typical generator in an Alaska wind farm now is likely rated at 1.5-MW capacity, compared to the single-kilowatt (kW) machines present in 1984. Installed capacity has mushroomed, illustrated by Unalakleet's 600-kW wind farm dwarfing the original three 10-kW machines included in the 1984 inventory. Kodiak Electric had three 1.5-MW turbines installed at Pillar Mountain in 2009, with three additional turbines of 4.5-MW capacity installed in 2012. Utilities now actively plan for wind generation and compete for state funding. State of Alaska energy policy provides the context for energy project decision-making. Substantial renewable energy fund (REF) awards--$202,000,000 to date for 227 REF projects in the first 5 cycles of funding--along with numerous energy conservation programs--are now in place. Increasing investment in wind is driven by multiple factors. Stakeholders have interests both in public policy and meeting private investment objectives. Wind generator investors should consider project economics and potential impacts of energy decisions on human health. Specifically this article considers: changing environmental conditions in remote Alaska villages, impacts associated with climate change on human health, progress in

  12. Renewable energy and sustainable communities: Alaska's wind generator experience†

    Directory of Open Access Journals (Sweden)

    R. Steven Konkel

    2013-08-01

    Full Text Available Background . In 1984, the Alaska Department of Commerce and Economic Development (DCED issued the State's first inventory/economic assessment of wind generators, documenting installed wind generator capacity and the economics of replacing diesel-fuel-generated electricity. Alaska's wind generation capacity had grown from hundreds of installed kilowatts to over 15.3 megawatts (MW by January 2012. Method . This article reviews data and conclusions presented in “Alaska's Wind Energy Systems; Inventory and Economic Assessment” (1. (Alaska Department of Commerce and Economic Development, S. Konkel, 1984. It provides a foundation and baseline for understanding the development of this renewable energy source. Results . Today's technologies have evolved at an astonishing pace; a typical generator in an Alaska wind farm now is likely rated at 1.5-MW capacity, compared to the single-kilowatt (kW machines present in 1984. Installed capacity has mushroomed, illustrated by Unalakleet's 600-kW wind farm dwarfing the original three 10-kW machines included in the 1984 inventory. Kodiak Electric had three 1.5-MW turbines installed at Pillar Mountain in 2009, with three additional turbines of 4.5-MW capacity installed in 2012. Utilities now actively plan for wind generation and compete for state funding. Discussion . State of Alaska energy policy provides the context for energy project decision-making. Substantial renewable energy fund (REF awards – $202,000,000 to date for 227 REF projects in the first 5 cycles of funding – along with numerous energy conservation programs – are now in place. Increasing investment in wind is driven by multiple factors. Stakeholders have interests both in public policy and meeting private investment objectives. Wind generator investors should consider project economics and potential impacts of energy decisions on human health. Specifically this article considers: a. changing environmental conditions in remote Alaska

  13. Renewable energy and sustainable communities: Alaska's wind generator experience†

    Science.gov (United States)

    Konkel, R. Steven

    2013-01-01

    Background In 1984, the Alaska Department of Commerce and Economic Development (DCED) issued the State's first inventory/economic assessment of wind generators, documenting installed wind generator capacity and the economics of replacing diesel-fuel-generated electricity. Alaska's wind generation capacity had grown from hundreds of installed kilowatts to over 15.3 megawatts (MW) by January 2012. Method This article reviews data and conclusions presented in “Alaska's Wind Energy Systems; Inventory and Economic Assessment” (1). (Alaska Department of Commerce and Economic Development, S. Konkel, 1984). It provides a foundation and baseline for understanding the development of this renewable energy source. Results Today's technologies have evolved at an astonishing pace; a typical generator in an Alaska wind farm now is likely rated at 1.5-MW capacity, compared to the single-kilowatt (kW) machines present in 1984. Installed capacity has mushroomed, illustrated by Unalakleet's 600-kW wind farm dwarfing the original three 10-kW machines included in the 1984 inventory. Kodiak Electric had three 1.5-MW turbines installed at Pillar Mountain in 2009, with three additional turbines of 4.5-MW capacity installed in 2012. Utilities now actively plan for wind generation and compete for state funding. Discussion State of Alaska energy policy provides the context for energy project decision-making. Substantial renewable energy fund (REF) awards – $202,000,000 to date for 227 REF projects in the first 5 cycles of funding – along with numerous energy conservation programs – are now in place. Increasing investment in wind is driven by multiple factors. Stakeholders have interests both in public policy and meeting private investment objectives. Wind generator investors should consider project economics and potential impacts of energy decisions on human health. Specifically this article considers:changing environmental conditions in remote Alaska villages,impacts associated

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

    DEFF Research Database (Denmark)

    Sørensen, Mette; Lühdorf, Pernille; Ketzel, Matthias

    2014-01-01

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

  15. Modeling and Parameter Estimation of a Small Wind Generation System

    Directory of Open Access Journals (Sweden)

    Carlos A. Ramírez Gómez

    2013-11-01

    Full Text Available The modeling and parameter estimation of a small wind generation system is presented in this paper. The system consists of a wind turbine, a permanent magnet synchronous generator, a three phase rectifier, and a direct current load. In order to estimate the parameters wind speed data are registered in a weather station located in the Fraternidad Campus at ITM. Wind speed data were applied to a reference model programed with PSIM software. From that simulation, variables were registered to estimate the parameters. The wind generation system model together with the estimated parameters is an excellent representation of the detailed model, but the estimated model offers a higher flexibility than the programed model in PSIM software.

  16. Issues and regulatory requirements for the connection of wind generation

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez Alvarez, J.M. [National University of San Juan (Argentina)], E-mail: jgimenez@unsj.edu.ar; Gomez Targarona, J.C. [National University of Rio Cuarto, Cordoba (Argentina). Electric Power Systems Protection Institute (IPSEP)], E-mail: jcgomez@ing.unrc.edu.ar

    2009-07-01

    Pollution problems such as greenhouse effect as well as the high value and volatility of fuel prices have forced and accelerated the development and use of renewable energy sources. In this work a complete revision of wind generation is presented. In the first part a brief history of the wind energy developments is detailed. Next, some commentaries related to the present and future state are made. Then, a revision of the modern structures of wind generation is realized. In fourth place it is included a brief comparison between small and big size turbines. Then, different types of energy storage are mentioned. Finally regulatory aspects are discussed, respect to the treatment of the technical problems. (author)

  17. Exploration of dispatch model integrating wind generators and electric vehicles

    International Nuclear Information System (INIS)

    Haque, A.N.M.M.; Ibn Saif, A.U.N.; Nguyen, P.H.; Torbaghan, S.S.

    2016-01-01

    Highlights: • A novel business model for the BRPs is analyzed. • Imbalance cost of wind generation is considered in the UC-ED model. • Smart charging of EVs is included into the UC-ED problem to mitigate the imbalance cost. • Effects of smart charging on generation cost, CO 2 emissions and total network load are assessed. - Abstract: In recent years, the share of renewable energy sources (RES) in the electricity generation mix has been expanding rapidly. However, limited predictability of the RES poses challenges for traditional scheduling and dispatching mechanisms based on unit commitment (UC) and economic dispatch (ED). This paper presents an advanced UC-ED model to incorporate wind generators as RES-based units alongside conventional centralized generators. In the proposed UC-ED model, an imbalance cost is introduced reflecting the wind generation uncertainty along with the marginal generation cost. The proposed UC-ED model aims to utilize the flexibility of fleets of plug-in electric vehicles (PEVs) to optimally compensate for the wind generation uncertainty. A case study with 15 conventional units and 3 wind farms along with a fixed-sized PEV fleet demonstrates that shifting of PEV fleets charging at times of high wind availability realizes generation cost savings. Nevertheless, the operational cost saving incurred by controlled charging appears to diminish when dispatched wind energy becomes considerably larger than the charging energy of PEV fleets. Further analysis of the results reveals that the effectiveness of PEV control strategy in terms of CO 2 emission reduction is strongly coupled with generation mix and the proposed control strategy is favored in cases where less pollutant-based plants like nuclear and hydro power are profoundly dominant.

  18. Operations model for utilities using wind-generator arrays

    Science.gov (United States)

    Schlueter, R. A.; Park, G. L.; Dorsey, J.; Lotfalian, M.; Shayanfar, A.

    1981-05-01

    The effects that various combinations of wind regime, array configuration and penetrations, and system characteristics have on system variables such as area control error, frequency, interchange power and spinning reserve are discussed. The characteristics of the combinations causing system operating stress or operating problems are denoted and methods for estimating effects on a simplified and on a detailed simulation basis are reported. Methods for reducing operating problems are suggested and involve array configurations, penetration, unit commitment and dispatch changes, and wind generator controls.

  19. A community small-scale wind generation project in Peru

    OpenAIRE

    Ferrer Martí, Laia; Garwood, Anna; Chiroque, José; Escobar, Rafael; Coello, Javier; Castro, Miguel

    2010-01-01

    Electrification systems based on renewable energy have proven to be suitable for providing decentralized electricity to isolated communities. Electricity generated through wind power is one of the technical options available, although infrequently used to date. This article aims to describe the main aspects of technical design, implementation and management of the first small-scale community wind generation project for rural electrification in Peru. This project took place in t...

  20. Auditory map reorganization and pitch discrimination in adult rats chronically exposed to low-level ambient noise

    Science.gov (United States)

    Zheng, Weimin

    2012-01-01

    Behavioral adaption to a changing environment is critical for an animal's survival. How well the brain can modify its functional properties based on experience essentially defines the limits of behavioral adaptation. In adult animals the extent to which experience shapes brain function has not been fully explored. Moreover, the perceptual consequences of experience-induced changes in the brains of adults remain unknown. Here we show that the tonotopic map in the primary auditory cortex of adult rats living with low-level ambient noise underwent a dramatic reorganization. Behaviorally, chronic noise-exposure impaired fine, but not coarse pitch discrimination. When tested in a noisy environment, the noise-exposed rats performed as well as in a quiet environment whereas the control rats performed poorly. This suggests that noise-exposed animals had adapted to living in a noisy environment. Behavioral pattern analyses revealed that stress or distraction engendered by the noisy background could not account for the poor performance of the control rats in a noisy environment. A reorganized auditory map may therefore have served as the neural substrate for the consistent performance of the noise-exposed rats in a noisy environment. PMID:22973201

  1. 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

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

    Science.gov (United States)

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

    2018-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Miriam Romagosa

    2017-04-01

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

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

    Science.gov (United States)

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

    2014-08-01

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

  5. Generation Expansion Planning Considering Integrating Large-scale Wind Generation

    DEFF Research Database (Denmark)

    Zhang, Chunyu; Ding, Yi; Østergaard, Jacob

    2013-01-01

    necessitated the inclusion of more innovative and sophisticated approaches in power system investment planning. A bi-level generation expansion planning approach considering large-scale wind generation was proposed in this paper. The first phase is investment decision, while the second phase is production...... optimization decision. A multi-objective PSO (MOPSO) algorithm was introduced to solve this optimization problem, which can accelerate the convergence and guarantee the diversity of Pareto-optimal front set as well. The feasibility and effectiveness of the proposed bi-level planning approach and the MOPSO...

  6. Reactive power management of power networks with wind generation

    CERN Document Server

    Amaris, Hortensia; Ortega, Carlos Alvarez

    2012-01-01

    As the energy sector shifts and changes to focus on renewable technologies, the optimization of wind power becomes a key practical issue. Reactive Power Management of Power Networks with Wind Generation brings into focus the development and application of advanced optimization techniques to the study, characterization, and assessment of voltage stability in power systems. Recent advances on reactive power management are reviewed with particular emphasis on the analysis and control of wind energy conversion systems and FACTS devices. Following an introduction, distinct chapters cover the 5 key

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

    Science.gov (United States)

    Kim, Seongryong; Tkalčić, Hrvoje; Rhie, Junkee

    2017-07-01

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

  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. Design of High Performance Permanent-Magnet Synchronous Wind Generators

    Directory of Open Access Journals (Sweden)

    Chun-Yu Hsiao

    2014-11-01

    Full Text Available This paper is devoted to the analysis and design of high performance permanent-magnet synchronous wind generators (PSWGs. A systematic and sequential methodology for the design of PMSGs is proposed with a high performance wind generator as a design model. Aiming at high induced voltage, low harmonic distortion as well as high generator efficiency, optimal generator parameters such as pole-arc to pole-pitch ratio and stator-slot-shoes dimension, etc. are determined with the proposed technique using Maxwell 2-D, Matlab software and the Taguchi method. The proposed double three-phase and six-phase winding configurations, which consist of six windings in the stator, can provide evenly distributed current for versatile applications regarding the voltage and current demands for practical consideration. Specifically, windings are connected in series to increase the output voltage at low wind speed, and in parallel during high wind speed to generate electricity even when either one winding fails, thereby enhancing the reliability as well. A PMSG is designed and implemented based on the proposed method. When the simulation is performed with a 6 Ω load, the output power for the double three-phase winding and six-phase winding are correspondingly 10.64 and 11.13 kW. In addition, 24 Ω load experiments show that the efficiencies of double three-phase winding and six-phase winding are 96.56% and 98.54%, respectively, verifying the proposed high performance operation.

  10. Wind Generation Participation in Power System Frequency Response: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, Vahan; Zhang, Yingchen

    2017-01-01

    The electrical frequency of an interconnected power system must be maintained close its nominal level at all times. Excessive under- and overfrequency excursions can lead to load shedding, instability, machine damage, and even blackouts. There is a rising concern in the electric power industry in recent years about the declining amount of inertia and primary frequency response (PFR) in many interconnections. This decline may continue due to increasing penetrations of inverter-coupled generation and the planned retirements of conventional thermal plants. Inverter-coupled variable wind generation is capable of contributing to PFR and inertia with a response that is different from that of conventional generation. It is not yet entirely understood how such a response will affect the system at different wind power penetration levels. The modeling work presented in this paper evaluates the impact of wind generation's provision of these active power control strategies on a large, synchronous interconnection. All simulations were conducted on the U.S. Western Interconnection with different levels of instantaneous wind power penetrations (up to 80%). The ability of wind power plants to provide PFR - and a combination of synthetic inertial response and PFR - significantly improved the frequency response performance of the system.

  11. Analysis of the levels of ambient noise present in the Colonia Auditorium (October 2001)

    Science.gov (United States)

    Jalisco, Zapopan; Palafox, Lourdes; Orozco, Martha; Rodriguez, Erika

    2002-11-01

    The study area is located in the city of Guadalajara, defined by: delimited in the north by the Gonzlez Gallo street; in the south by the Anillo Perifrico street; in the east by Avenida Mezquitan; and in the west by Avenida Alcalde. There were 38 measurement points outside the auditorium and 25 inside. A poll was conducted among the neighbors and visitors in both areas, getting 70 replies. Noise levels were between 41-101 dB(A) on the outside, average Leq on the outside was 64.5 dB(A), and inside was 80.15 dB(A). The conclusion is that the whole area is affected by traffic noise, as well by the huge number of visitors, the electric games, and the electric generators that supply energy to them. On the outside 21 points were above 65 dB(A), which means that 55% were above the average; on the inside, 100% were above 65 dB(A). Thus the neighbors are exposed to high noise levels due to the festivities during October. The biggest problem, however, is the noise exposure of the workers inside the auditorium, due to music, games, people, and electric generators.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Background: Road traffic is a main source of air pollution and noise. Both exposures have been associated with type 2 diabetes, but associations with gestational diabetes mellitus (GDM) have been studied less. Objectives: We aimed to examine single and joint associations of exposure to air pollut...

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

    Science.gov (United States)

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

    2017-11-01

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

  14. Understanding the formation of the Ontong Java Plateau through joint ambient noise earthquake tomography and laboratory modeling

    Science.gov (United States)

    Covellone, B. M.; Szwaja, S.; Savage, B. K.; Shen, Y.; Kincaid, C. R.

    2013-12-01

    Current knowledge of the Ontong Java Plateau (OJP) comes from a broad range of research disciplines. Despite decades of work, numerous hypotheses on the origin of the OJP do not fully address all of the geophysical and geochemical observations. A more complete image of the current lower crust and upper mantle seismic structure beneath the plateau will provide a link between the plateau's 120 Ma complex history and it's formation. We investigate the anomalous wave speed structure underlying the OJP using an iterative, full-waveform, joint ambient noise and earthquake tomography approach. A 3-dimensional wave speed model is determined from ambient noise data at periods between 25 and 200 seconds. Data from over 100 earthquakes, recorded between 1990 and 2012, are then added to the inversion to improve data coverage and model resolution. The combination of datasets allows us to best exploit the limited station distribution in the Pacific, resulting in resolution better than 5-degrees beneath the plateau and extending to depths greater than 350 km. To improve our sense of expected deformation patterns for sub-plateau mantle through geologic time, a set of laboratory models were run where OJP residuum viscosity is changed relative to the ambient fluid. Models focus on the interaction between OJP residuum and the rollback-driven flow associated with passage of the Tonga subduction system to the south. Model results show dramatic thinning and extraction of the southern portion of sub-OJP fluid due to subduction induced torroidal flows. Significant distortion of the sub-OJP material over roughly the last 40 Ma is predicted in cases where residuum is either stronger or weaker than ambient fluid. The results of this work confirm an anomalously slow mantle beneath the OJP extending to depths greater than 300 km and provide high-resolution images constraining the magnitude and dimensions of wave speed anomalies that can be used to determine thermal and compositional variations

  15. 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 ...

  16. Output power control of two coupled wind generators

    Directory of Open Access Journals (Sweden)

    A Boukhelifa

    2016-09-01

    Full Text Available In this paper we are interested to the power control of two wind generators coupled to the network through power converters. Every energy chain conversion is composed of a wind turbine, a gearbox, a Double Fed Induction Generator (DFIG, two PWM converters and a DC bus. The power exchange and the DC voltage are controlled by the use of proportional integral correctors. For our study, initially we have modeled all the components of the one system energy conversion, and then we have simulated its behavior using Matlab/Simulink. In another part of this paper we present the analysis of the interaction and the powerflow between the two aerogenerators following a disturbance due to wind speed on every turbine. Also we have considered a connection fault to the DC bus. In each case the assessment of power brought into play is checked. Simulation tests are established.

  17. Transient Stability Enhancement of the Power System with Wind Generation

    Directory of Open Access Journals (Sweden)

    Ashwani Kumar Chandel

    2011-08-01

    Full Text Available Transient stability analysis of a power system with wind generation has been addressed in this paper. The effects of automatic voltage regulators, power system stabilizers, and static synchronous compensators on transient stability of a power system are investigated. Various simulation results show that addition of power system stabilizer and static synchronous compensators reduce the rotor angle oscillations. However, the static synchronous compensator shows better damping characteristics and improves the stability of the wind integrated system. It has been established that the static synchronous compensator damps out the speed oscillations in the shaft of the constant speed wind turbine. A transient impact index has been proposed to prove that the static compensator damps out the rotor oscillations.

  18. Batteries for storage of wind-generated energy

    Science.gov (United States)

    Schwartz, H. J.

    1973-01-01

    Cost effectiveness characteristics of conventional-, metal gas-, and high energy alkali metal-batteries for wind generated energy storage are considered. A lead-acid battery with a power density of 20 to 30 watt/hours per pound is good for about 1500 charge-discharge cycles at a cost of about $80 per kilowatt hour. A zinc-chlorine battery that stores chlorine as solid chlorine hydrate at temperatures below 10 C eliminates the need to handle gaseous chlorine; its raw material cost are low and inexpensive carbon can be used for the chlorine electrode. This system has the best chance to replace lead-acid. Exotic alkali metal batteries are deemed too costly at the present stage of development.

  19. Optimization of Multibrid Permanent-Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, H.; Polinder, H.

    2009-01-01

    This paper investigates the cost-effective ranges of gearbox ratios and power ratings of multibrid permanent-magnet (PM) wind generator systems by using a design optimization method. First, the analytical model of a multibrid wind turbine concept consisting of a single-stage gearbox and a three......-phase radial-flux PM synchronous generator with a back-to-back power converter is presented. The design optimization is adopted with a genetic algorithm forminimizing generator system cost. To demonstrate the effectiveness of the developed electromagnetic design model, the optimization results of a 500-k......W direct-drive PM generator and a 1.5-MW multibrid PM generator with various gear ratios are, respectively, compared with those from other methods. Then, the optimal design approach is further employed for a range from 750 kW up to 10 MW. The optimization results of PM generator systems including direct...

  20. Interconnector capacity allocation in offshore grids with variable wind generation

    DEFF Research Database (Denmark)

    Schröder, Sascha Thorsten

    2013-01-01

    its generation flows only to the high-price market. Granting the high-price market income for wind generation as the opposite design option reduces congestion rents. Otherwise, compensation measures through support schemes or different balancing responsibilities may be discussed....... with onshore installations to reduce balancing demand. This is not necessarily the case if the interconnector capacity is sold through implicit or explicit auctions. Different design options are discussed and quantified for a number of examples based on Danish, Dutch, German and Norwegian power markets....... It is concluded that treating offshore generation as a single price zone within the interconnector reduces the wind operator’s ability to pool it with other generation. Furthermore, a single offshore price zone between two markets will always receive the lower spot market price of the neighbouring zones, although...

  1. Low cost infrastructure solutions for small embedded wind generators

    Energy Technology Data Exchange (ETDEWEB)

    Robb, C.

    2003-07-01

    This report gives details of a project to demonstrate novel economic solutions to increase the potential for installing small-scale embedded wind generator systems at many UK sites which have so far been dismissed as too difficult. Details are given of the first phase of the study which examined current solutions to infrastructure problems and potential techniques. The use of drilled rock anchor foundations to minimise the need for delivery of ready-mix concrete to wind turbine sites, and the use of a winch and A-frame system for erecting a wind turbine to avoid the use of cranes are discussed. The demonstration of the installation of a 50kW wind turbine on the Isle of Luing in Scotland where there is no access for cranes or larger vehicles in the second phase of the project is described. The potential for the use of these techniques on larger wind turbines is considered.

  2. The Impact of Offshore Wind Turbines on Underwater Ambient Noise Levels

    OpenAIRE

    Glegg, Stewart

    2015-01-01

    The underwater sound levels generated by offshore wind turbine farms is a concern because of the possible environmental impact on marine mammals. This paper will consider how sound generated by a wind turbine is transmitted into a shallow water channel. It is shown that the underwater sound levels can be calculated for a typical offshore wind turbine by using the theory of Chapman and Ward (1990) combined with aeroacoustic models of trailing edge noise on the wind turbine blades. A procedure ...

  3. Crustal structure determined from ambient noise tomography near the magmatic centers of the Coso region, southeastern California

    Science.gov (United States)

    Yang, Yingjie; Ritzwoller, Michael H.; Jones, Craig H.

    2011-02-01

    We apply seismic ambient noise tomography to image and investigate the shallow shear velocity structure beneath the Coso geothermal field and surrounding areas. Data from a PASSCAL experiment operated within the Coso geothermal field between 1998 and 2000 and surrounding broadband stations from the Southern California Seismic Network are acquired and processed. Daily cross correlations of ambient noise between all pairs of stations that overlapped in time of deployment were calculated and then stacked over the duration of deployment. Phase velocities of Rayleigh waves between 3 and 10 s periods are measured from the resulting cross correlations. Depending on the period, between about 300 and 600 reliable phase velocity measurements are inverted for phase velocity maps from 3 to 10 s periods, which in turn are inverted for a 3-D shear velocity model beneath the region. The resulting 3-D model reveals features throughout the region that correlate with surface geology. Beneath the Coso geothermal area shear velocities are generally depressed, a prominent low-velocity anomaly is resolved clearly within the top 2 km, no significant anomaly is seen below about 14 km depth, and a weakly resolved anomaly is observed between 6 and 12 km depth. The anomaly in the top 2 km probably results from geothermal alteration in the shallow subsurface, no magmatic body is imaged beneath 14 km depth, but the shear velocity anomaly between 6 and 12 km may be attributable to partial melt. The thickness and amplitude of the magma body trade off in the inversion and are ill determined. Low velocities in the regions surrounding Coso at depths near 7 km underlie areas with Miocene to recent volcanism, suggesting that some magmatic processing of the crust could be focused near this depth.

  4. 4-D permafrost thaw observations from ambient road traffic noise and a very dense distributed fiber optic sensing array

    Science.gov (United States)

    Lindsey, N.; Dou, S.; Martin, E. R.; Wagner, A. M.; Ajo Franklin, J. B.

    2017-12-01

    How does frozen soil thaw? The answer to this question affects hydrology, ecology, climate, and human infrastructure. We are using the local ambient noise field from a road recorded on a distributed fiber optic acoustic sensing (DAS) array to monitor the evolution in seismic parameters related to the top-down permafrost thaw process in the upper 10 m. Our field experiment demonstrates the advantages of "Large N" ambient noise studies using DAS, particularly to probe near surface critical zone dynamics. Over 60 days beginning in August 2016, we made continuous seismic recordings with a >4000 channel trenched fiber optic DAS dataset above a controlled permafrost warming demonstration experiment in Fairbanks, AK. The warming experiment accelerated the state of permafrost degradation by approximately two decades in a small 15 m x 20 m area, deepening the permafrost table from 4 m to 5.5 m. Continuous seismic DAS recording of high frequency surface waves (5-30 Hz) generated by vehicles traveling along a nearby road enables our investigation of hypothesized shear wave speed and attenuation changes, which lab measurements suggest may result from decreasing shear modulus and increasing saturation. We develop daily auto- and crosscorrelation function estimates using combinations of horizontal inline, collinear, and crossline DAS sensor orientations and vertical component geophone data, and then invert for maps of Love and Rayleigh wave speed that are sensitive to the upper 30 m. Many issues related to the accuracy, stability, and repeatability of the recovered empirical Green's tensor, as well as the sensitivity of the DAS sensor network will be considered.

  5. Crustal and uppermantle velocity structure of the northern Korean Peninsula constrained by ambient noise cross-correlations

    Science.gov (United States)

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

    2014-12-01

    The seismic velocity structure of the northern Korean Peninsula has not been well known because available seismic data observed inside the region is very rare. Therefore, constructing a one-dimensional (1-D) reference velocity model will be a meaningful first step to understand the detailed velocity structure and also the tectonic evolution of the region. In this study, we use two-year long (2010-2011) ambient noise data recorded by three component broadband seismometers of KIGAM, KMA, F-net, and IRIS networks surrounding the study area. Ambient noise cross-correlations are calculated for station pairs sampling the study area. Multiple filter technique is applied to measure group and phase velocity dispersions of the fundamental mode Rayleigh and Love waves for period ranges between 5 and 70 s, which are sensitive to shear wave velocities in the crust and uppermost mantle. Recently developed inversion method using the Bayesian technique is applied to estimate 1-D models of shear wave velocities and corresponding uncertainties. Combined with the Markov chain Monte Carlo (MCMC) technique, the posterior probability density is evaluated for given data and the prior. Boundaries, velocities, and anisotropy parameters of layers are searched together on the assumption of the layered half-space model. The used method automatically adjusts the number of layers and degree of data fitting by the Bayesian Information Criterion (BIC) estimation and scaling of the data-covariance matrix, respectively. The estimated anisotropic S-wave velocity model in the crust and upper-mantle can help to investigate tectonic processes of the region. For practical use, our velocity model for the Northern Korean Peninsula can be useful to enhance monitoring power of the underground nuclear tests in given area.

  6. Wind Generator & Biomass No-draft Gasification Hybrid

    Science.gov (United States)

    Hein, Matthew R.

    The premise of this research is that underutilized but vast intermittent renewable energy resources, such as wind, can become more market competitive by coupling with storable renewable energy sources, like biomass; thereby creating a firm capacity resource. Specifically, the Midwest state of South Dakota has immense wind energy potential that is not used because of economic and logistic barriers of electrical transmission or storage. Coupling the state's intermittent wind resource with another of the state's energy resources, cellulosic non-food biomass, by using a wind generator and no-draft biomass gasification hybrid system will result in a energy source that is both firm and storable. The average energy content of common biomass feedstock was determined, 14.8 MJ/kg (7.153 Btu/lb), along with the assumed typical biomass conversion efficiency of the no-draft gasifier, 65%, so that an average electrical energy round trip efficiency (RTE) of 214% can be expected (i.e. One unit of wind electrical energy can produce 2.14 kWh of electrical energy stored as syngas.) from a wind generator and no-draft biomass gasification system. Wind characteristics are site specific so this analysis utilizes a synthetic wind resource to represent a statistically sound gross representation of South Dakota's wind regime based on data from the Wind Resource Assessment Network (WRAN) locations. A synthetic wind turbine generated from common wind turbine power curves and scaled to 1-MW rated capacity was utilized for this analysis in order to remove equipment bias from the results. A standard 8,760-hour BIN Analysis model was constructed within HOMER, powerful simulation software developed by the National Renewable Energy Laboratory (NREL) to model the performance of renewable power systems. It was found that the optimum configuration on a per-megawatt-transmitted basis required a wind generator (wind farm) rated capacity of 3-MW with an anticipated annual biomass feedstock of 26,132 GJ

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

    Science.gov (United States)

    Pazzi, Veronica; Lotti, Alessia

    2017-04-01

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

  8. Variations of local seismic response in Benevento (Southern Italy) using earthquakes and ambient noise recordings

    Science.gov (United States)

    Improta, Luigi; di Giulio, Giuseppe; Rovelli, Antonio

    The city of Benevento (Southern Italy) has been repeatedly struck by large historical earthquakes. A heterogeneous geologic structure and widespread soft soil conditions make the estimation of site effects crucial for the seismic hazard assessment of the city. From 2000 until 2004, we installed seismic stations to collect earthquake data over zones with different geological conditions. Despite the high level of urban noise, we recorded more than 150 earthquakes at twelve sites. This data set yields the first, well documented experimental evidence for weak to moderate local amplifications. We investigated site effects primarily by the classical spectral ratio technique (CSR) using a rock station placed on the Benevento hill as reference. All sites in the Calore river valley and in the eastern part of the Benevento hill show a moderate high-frequency (f > 4 Hz) amplification peak. Conversely, sites in the Sabato river valley share weak-to-moderate amplification in a wide frequency band (from 1-2 to 7-10 Hz), without evident frequency peaks. Application of no-reference-site techniques to earthquake and noise data confirms the results of the CSRs in the sites of the Calore river valley and of the eastern part of the Benevento hill, but fails in providing indications for site effects in the Sabato river valley, being the H/V ratios nearly flat. One-dimensional modeling indicates that the ground motion amplification can be essentially explained in terms of a vertically varying geologic structure. High-frequency narrow peaks are caused by the strong impedance contrast existing between near-surface soft deposits and stiff cemented conglomerates. Conversely, broad-band amplifications in the Sabato river valley are likely due to a more complex layering with weak impedance contrasts both in the shallow and deep structure of the valley.

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

    Science.gov (United States)

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

    2017-12-01

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

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

    Science.gov (United States)

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

    2014-04-01

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

  11. Estimation of time varying system parameters from ambient response using improved Particle-Kalman filter with correlated noise

    Science.gov (United States)

    Sen, Subhamoy; Crinière, Antoine; Mevel, Laurent; Cerou, Frederic; Dumoulin, Jean

    2017-04-01

    within a PF environment that estimates the parameters. This facilitates employing relatively less expensive linear KF for linear state estimation problem while costly PF is employed only for parameter estimation. Additionally, the proposed algorithm also takes care of those systems for which system and measurement noises are not uncorrelated as it is commonly idealized in standard filtering algorithms. As an example, for mechanical systems under ambient vibration it happens when acceleration response is considered as measurement. Thus the process and measurement noise in these system descriptions are obviously correlated. For this, an improved description for the Kalman gain is developed. Further, to enhance the consistency of particle filtering based parameter estimation involving high dimensional parameter space, a new temporal evolution strategy for the particles is defined. This strategy aims at restricting the solution from diverging (up to the point of no return) because of an isolated event of infeasible estimation which is very much likely especially when dealing with high dimensional parameter space.

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

    Science.gov (United States)

    Kadiri, U. A.

    2016-12-01

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

  13. Performance evaluation of stand alone hybrid PV-wind generator

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, M. N. M.; Saharuddin, N. Z.; Sulaima, M. F.; Jali, Mohd Hafiz; Bukhari, W. M.; Bohari, Z. H. [Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya, 76100 Melaka (Malaysia); Yahaya, M. S. [Faculty of Engineering Technology, Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya, 76100 Melaka (Malaysia)

    2015-05-15

    This paper presents the performance evaluation of standalone hybrid system on Photovoltaic (PV)-Wind generator at Faculty of Electrical Engineering (FKE), UTeM. The hybrid PV-Wind in UTeM system is combining wind turbine system with the solar system and the energy capacity of this hybrid system can generate up to charge the battery and supply the LED street lighting load. The purpose of this project is to evaluate the performance of PV-Wind hybrid generator. Solar radiation meter has been used to measure the solar radiation and anemometer has been used to measure the wind speed. The effectiveness of the PV-Wind system is based on the various data that has been collected and compared between them. The result shows that hybrid system has greater reliability. Based on the solar result, the correlation coefficient shows strong relationship between the two variables of radiation and current. The reading output current followed by fluctuate of solar radiation. However, the correlation coefficient is shows moderate relationship between the two variables of wind speed and voltage. Hence, the wind turbine system in FKE show does not operate consistently to produce energy source for this hybrid system compare to PV system. When the wind system does not fully operate due to inconsistent energy source, the other system which is PV will operate and supply the load for equilibrate the extra load demand.

  14. Fuzzy logic based variable speed wind generation system

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, M.G. [Sao Paulo Univ., SP (Brazil). Escola Politecnica. PMC - Mecatronica; Bose, B.K. [Tennessee Univ., Knoxville, TN (United States). Dept. of Electrical Engineering; Spiegel, Ronal J. [Environmental Protection Agency, Research Triangle Park, NC (United States). Air and Energy Engineering Research Lab.

    1996-12-31

    This work demonstrates the successful application of fuzzy logic to enhance the performance and control of a variable speed wind generation system. A maximum power point tracker control is performed with three fuzzy controllers, without wind velocity measurement, and robust to wind vortex and turbine torque ripple. A squirrel cage induction generator feeds the power to a double-sided PWM converter system which pumps the power to a utility grid or supplies to an autonomous system. The fuzzy logic controller FLC-1 searches on-line the generator speed so that the aerodynamic efficiency of the wind turbine is optimized. A second fuzzy controller FLC-2 programs the machine flux by on-line search so as to optimize the machine-converter system wind vortex. Detailed analysis and simulation studies were performed for development of the control strategy and fuzzy algorithms, and a DSP TMS320C30 based hardware with C control software was built for the performance evaluation of a laboratory experimental set-up. The theoretical development was fully validated and the system is ready to be reproduced in a higher power installation. (author) 7 refs., 3 figs., 1 tab.

  15. Performance evaluation of stand alone hybrid PV-wind generator

    Science.gov (United States)

    Nasir, M. N. M.; Saharuddin, N. Z.; Sulaima, M. F.; Jali, Mohd Hafiz; Bukhari, W. M.; Bohari, Z. H.; Yahaya, M. S.

    2015-05-01

    This paper presents the performance evaluation of standalone hybrid system on Photovoltaic (PV)-Wind generator at Faculty of Electrical Engineering (FKE), UTeM. The hybrid PV-Wind in UTeM system is combining wind turbine system with the solar system and the energy capacity of this hybrid system can generate up to charge the battery and supply the LED street lighting load. The purpose of this project is to evaluate the performance of PV-Wind hybrid generator. Solar radiation meter has been used to measure the solar radiation and anemometer has been used to measure the wind speed. The effectiveness of the PV-Wind system is based on the various data that has been collected and compared between them. The result shows that hybrid system has greater reliability. Based on the solar result, the correlation coefficient shows strong relationship between the two variables of radiation and current. The reading output current followed by fluctuate of solar radiation. However, the correlation coefficient is shows moderate relationship between the two variables of wind speed and voltage. Hence, the wind turbine system in FKE show does not operate consistently to produce energy source for this hybrid system compare to PV system. When the wind system does not fully operate due to inconsistent energy source, the other system which is PV will operate and supply the load for equilibrate the extra load demand.

  16. Performance evaluation of stand alone hybrid PV-wind generator

    International Nuclear Information System (INIS)

    Nasir, M. N. M.; Saharuddin, N. Z.; Sulaima, M. F.; Jali, Mohd Hafiz; Bukhari, W. M.; Bohari, Z. H.; Yahaya, M. S.

    2015-01-01

    This paper presents the performance evaluation of standalone hybrid system on Photovoltaic (PV)-Wind generator at Faculty of Electrical Engineering (FKE), UTeM. The hybrid PV-Wind in UTeM system is combining wind turbine system with the solar system and the energy capacity of this hybrid system can generate up to charge the battery and supply the LED street lighting load. The purpose of this project is to evaluate the performance of PV-Wind hybrid generator. Solar radiation meter has been used to measure the solar radiation and anemometer has been used to measure the wind speed. The effectiveness of the PV-Wind system is based on the various data that has been collected and compared between them. The result shows that hybrid system has greater reliability. Based on the solar result, the correlation coefficient shows strong relationship between the two variables of radiation and current. The reading output current followed by fluctuate of solar radiation. However, the correlation coefficient is shows moderate relationship between the two variables of wind speed and voltage. Hence, the wind turbine system in FKE show does not operate consistently to produce energy source for this hybrid system compare to PV system. When the wind system does not fully operate due to inconsistent energy source, the other system which is PV will operate and supply the load for equilibrate the extra load demand

  17. 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

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

    Science.gov (United States)

    Cheng, Xin

    2009-12-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

  1. Shallow structure of Deception Island, Antarctica, from correlations of ambient seismic noise on a set of dense seismic arrays

    Science.gov (United States)

    Luzón, F.; Almendros, J.; García-Jerez, A.

    2011-05-01

    We investigated the shallow velocity structure of Deception Island volcano, Antarctica, using correlations of ambient seismic noise. We selected long records of noise obtained by eight seismic arrays deployed along the inner coast of Deception during the period 2003-2005. Using these data, we calculated average dispersion curves and estimated local 1-D velocity models for the array sites. The combination of these profiles allowed us to obtain a comprehensive model of the shallow velocity structure of the island. The volcano is composed of relatively soft layers of pyroclastic deposits and sediments extending to a depth of about 400 m, with different degrees of compaction. Two layers with thicknesses of about 100 and 300 m and S-wave velocities of around 0.2-0.8 and 0.7-1.1 km s-1, respectively, can be differentiated. The deeper structure is highly variable in terms of wave velocities and layer depths. Although the resolving capabilities are reduced for these layers, the larger S-wave velocities in the range 1.3-2.8 km s-1 indicate that they can be associated with pre-caldera structures and products. There are substantial differences between the different models, which can be spatially related to heterogeneities in the volcano structure. The lowest S-wave velocities may be related to the alterations produced by hydrothermal activity near the surface. On the contrary, the largest velocities occur near the caldera border, revealing the presence of compact materials at shallow depths. Sharp lateral variations can also be observed in the northwest of the bay, which points to the presence of NW-SE faults and/or strong velocity gradients.

  2. Polarization Analysis of Ambient Seismic Noise Green's Functions for Monitoring Glacial State

    Science.gov (United States)

    Fry, B.; Horgan, H. J.; Levy, R. H.; Bertler, N. A. N.

    2017-12-01

    Analysis of continuously recorded background seismic noise has emerged as a powerful technique to monitor changes within the Earth. In a process analogous to Einstein's 'Brownian motion', seismic energy enters the Earth through a variety of mechanisms and then is dissipated through scattering processes or through a semi-random distribution of sources. Eventually, in stratified media, some of this energy assembles itself in coherent packets and propagates as seismic surface waves. Through careful analysis of these waves as recorded by two seismic stations over a short period of time, we can reconstruct Empirical Green's Functions (EGF). EGF are sensitive to the material through which the waves are travelling between the two stations. They can thus provide 4D estimates of material properties such as seismic velocity and anisotropy. We specifically analyze both the bulk velocity and the complex phase of these EGF to look for subtle changes in velocity with direction of propagation as well as the nature of particle polarization and ellipticity. These characteristics can then be used as a proxy for contemporaneous stress and strain or 'inherited' strain. Similar approaches have proven successful in mapping stresses and strain in the crust, on plate interface faults, volcanoes, and on glaciers and the Greenland ice sheet. We will present results from applying this approach to continuous broadband data recorded on the West Antarctic Ice Sheet through the Polenet project. Our results suggest that we can reconstruct EGF at least between frequencies of 300mHz and 50mHz for time periods, providing information about the contemporary state of ice and underlying lithosphere on a seasonal or annual basis. Our primary goals are determining glacial state by linking wave propagation to material fabric on micro (crystal orientation) and macro (strain marker) scales and well as rebound processes in the lithosphere during glacial loading and unloading. We will present our current

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

    Science.gov (United States)

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

    2017-11-01

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

  4. 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

  5. The seismic wave speed structure of the Ontong Java Plateau determined from joint ambient noise and earthquake waveform data

    Science.gov (United States)

    Covellone, B. M.; Savage, B. K.; Shen, Y.

    2014-12-01

    The Ontong Java Plateau (OJP) represents the result of a significant event in the Earth's geologic history. Limited geophysical and geochemical data, as well as the plateau's relative isolation in the Pacific Ocean, have made interpretation of the modern day geologic structure and its 120 Ma formation history difficult. Here we present the highest resolution images to date of the wave speed structure of the OJP region. We use an iterative finite-frequency tomography methodology and a unique data set that combines empirical Green's functions extracted from ambient noise and earthquake waveforms. The uniqueness and combination of datasets allow us to best exploit the limited station distribution in the Pacific and image wave speed structures between 35 km and greater than 250 km into the Earth. We image a region of fast shear wave speeds, greater than 4.75 km/s, that extends to greater than 100 km beneath the plateau. The wave speeds are similar to as observed in cratonic environments and are consistent with a compositional anomaly likely a result of eclogite entrainment during the plateau's formation.

  6. 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.

  7. Near-bottom hydrophone measurements of ambient noise and sperm whale vocalizations in the northern Gulf of Mexico

    Science.gov (United States)

    Newcomb, Joal; Fisher, Robert; Field, Robert; Turgut, Altan; Ioup, George; Ioup, Juliette; Rayborn, Grayson; Kuczaj, Stan; Caruthers, Jerald; Goodman, Ralph; Sidorovskaia, Natalia

    2002-05-01

    Three bottom-moored hydrophones, 50 m above the bottom, were placed on a downslope line, ending at the largest concentration of sperm whale sightings in the northern Gulf of Mexico, in 600 m, 800 m, and 1000 m water depths. These depths were chosen after upslope propagation modeling, using historical databases, showed transmission losses greater than 110 dB at hydrophones near the bottom in water shallower than 600 m for a 500 m deep source at the 1000 m contour. These autonomously recording hydrophones were environmental acoustic recording system (EARS) buoys obtained from the Naval Oceanographic Office. They were capable of recording signals up to 5500 Hz continuously for 36 days and were deployed from July 17 through August 21. During this period a major marine mammal exercise was being conducted at the surface by the Minerals Management Service and the National Marine Fisheries Service, with other government and university scientists, in which temporary acoustic recording devices were attached to the whales and the whales were monitored by a surface towed array. Our near-bottom measurements of ambient noise and sperm whale vocalizations are discussed and compared to those surface and on-whale measurements. [Research supported by ONR.

  8. Crustal and uppermost mantle structure of southern Norway: results from surface wave analysis of ambient seismic noise and earthquake data

    Science.gov (United States)

    Köhler, Andreas; Weidle, Christian; Maupin, Valérie

    2012-12-01

    We use ambient seismic noise and earthquake recordings on a temporary regional network in southern Norway to produce Rayleigh and Love wave phase velocity maps from 3 to 67 s period. Local dispersion curves are then jointly inverted for a 3-D shear wave velocity model of the region. We perform a two-step inversion approach. First, a direct search, Monte Carlo algorithm is applied to find best fitting isotropic velocity depth profiles. Those profiles are then used as initial models for a linearised inversion which takes into account radial anisotropy in the shear wave structure. Results reveal crustal as well as uppermost mantle structures in the studied region. Velocity anomalies in the upper crust are rather small in amplitude and can in most parts be related to surface geology in terms of rock densities. Old tectonic units like the Oslo Graben (300-240 Ma) and the Caledonian nappes (440-410 Ma) are clearly imaged. Furthermore, we find clear indications for localized crustal anisotropy of about 3 per cent. Despite generally poor resolution of interface depths in surface wave inversion, we find lateral variation of crustal thickness in agreement with previous studies. We are able to confirm and locate the transition from a slow lithospheric upper mantle underneath southern Norway to a fast shield-like mantle towards Sweden.

  9. Time-Lapse Monitoring with 4D Seismic Coda Waves in Active, Passive and Ambient Noise Data

    Science.gov (United States)

    Lumley, D. E.; Kamei, R.; Saygin, E.; Shragge, J. C.

    2017-12-01

    The Earth's subsurface is continuously changing, due to temporal variations in fluid flow, stress, temperature, geomechanics and geochemistry, for example. These physical changes occur at broad tectonic and earthquake scales, and also at very detailed near-surface and reservoir scales. Changes in the physical states of the earth cause time-varying changes in the physical properties of rocks and fluids, which can be monitored with natural or manmade seismic waves. Time-lapse (4D) seismic monitoring is important for applications related to natural and induced seismicity, hydrocarbon and groundwater reservoir depletion, CO2 sequestration etc. An exciting new research area involves moving beyond traditional methods in order to use the full complex time-lapse scattered wavefield (4D coda waves) for both manmade active-source 3D/4D seismic data, and also to use continuous recordings of natural-source passive seismic data, especially (micro) earthquakes and ocean ambient noise. This research involves full wave-equation approaches including waveform inversion (FWI), interferometry, Large N sensor arrays, "big data" information theory, and high performance supercomputing (HPC). I will present high-level concepts and recent data results that are quite spectacular and highly encouraging.

  10. Three-dimensional S-wave velocity model of the Bohemian Massif from Bayesian ambient noise tomography

    Science.gov (United States)

    Valentová, Lubica; Gallovič, František; Maierová, Petra

    2017-10-01

    We perform two-step surface wave tomography of phase-velocity dispersion curves obtained by ambient noise cross-correlations in the Bohemian Massif. In the first step, the inter-station dispersion curves were inverted for each period (ranging between 4 and 20 s) separately into phase-velocity maps using 2D adjoint method. In the second step, we perform Bayesian inversion of the set of the phase-velocity maps into an S-wave velocity model. To sample the posterior probability density function, the parallel tempering algorithm is employed providing over 1 million models. From the model samples, not only mean model but also its uncertainty is determined to appraise the reliable features. The model is correlated with known main geologic structures of the Bohemian Massif. The uppermost low-velocity anomalies are in agreement with thick sedimentary basins. In deeper parts (4-20 km), the S-wave velocity anomalies correspond, in general, to main tectonic domains of the Bohemian Massif. The exception is a stable low-velocity body in the middle of the high-velocity Moldanubian domain and high-velocity body resembling a promontory of the Moldanubian into the Teplá-Barrandian domain. The most pronounced (high-velocity) anomaly is located beneath the Eger Rift that is a part of a Tertiary rift system across Europe.

  11. High penetration wind generation impacts on spot prices in the Australian national electricity market

    International Nuclear Information System (INIS)

    Cutler, Nicholas J.; Boerema, Nicholas D.; MacGill, Iain F.; Outhred, Hugh R.

    2011-01-01

    This paper explores wind power integration issues for the South Australian (SA) region of the Australian National Electricity Market (NEM) by assessing the interaction of regional wind generation, electricity demand and spot prices over 2 recent years of market operation. SA's wind energy penetration has recently surpassed 20% and it has only a limited interconnection with other regions of the NEM. As such, it represents an interesting example of high wind penetration in a gross wholesale pool market electricity industry. Our findings suggest that while electricity demand continues to have the greatest influence on spot prices in SA, wind generation levels have become a significant secondary influence, and there is an inverse relationship between wind generation and price. No clear relationship between wind generation and demand has been identified although some periods of extremely high demand may coincide with lower wind generation. Periods of high wind output are associated with generally lower market prices, and also appear to contribute to extreme negative price events. The results highlight the importance of electricity market and renewable policy design in facilitating economically efficient high wind penetrations. - Highlights: → In South Australia (SA) wind generation is having an influence on market prices. → Little or no correlation is found between wind generation and demand. → Wind farms in SA are receiving a lower average price than in other States. → The results highlight the importance of appropriate electricity market design.

  12. Low-Cost Superconducting Wire for Wind Generators: High Performance, Low Cost Superconducting Wires and Coils for High Power Wind Generators

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-01-01

    REACT Project: The University of Houston will develop a low-cost, high-current superconducting wire that could be used in high-power wind generators. Superconducting wire currently transports 600 times more electric current than a similarly sized copper wire, but is significantly more expensive. The University of Houston’s innovation is based on engineering nanoscale defects in the superconducting film. This could quadruple the current relative to today’s superconducting wires, supporting the same amount of current using 25% of the material. This would make wind generators lighter, more powerful and more efficient. The design could result in a several-fold reduction in wire costs and enable their commercial viability of high-power wind generators for use in offshore applications.

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

    Science.gov (United States)

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

    2018-04-01

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

  14. 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

  15. Ambient noise tomography reveals basalt and sub-basalt velocity structure beneath the Faroe Islands, North Atlantic

    Science.gov (United States)

    Sammarco, Carmelo; Cornwell, David G.; Rawlinson, Nicholas

    2017-11-01

    Ambient noise tomography is applied to seismic data recorded by a portable array of seismographs deployed throughout the Faroe Islands in an effort to illuminate basalt sequences of the North Atlantic Igneous Province, as well as underlying sedimentary layers and Precambrian basement. Rayleigh wave empirical Green's functions between all station pairs are extracted from the data via cross-correlation of long-term recordings, with phase weighted stacking implemented to boost signal-to-noise ratio. Dispersion analysis is applied to extract inter-station group travel-times in the period range 0.5-15 s, followed by inversion for period-dependent group velocity maps. Subsequent inversion for 3-D shear wave velocity reveals the presence of significant lateral heterogeneity (up to 25%) in the crust. Main features of the final model include: (i) a near-surface low velocity layer, interpreted to be the Malinstindur Formation, which comprises subaerial compound lava flows with a weathered upper surface; (ii) a sharp velocity increase at the base of the Malinstindur Formation, which may mark a transition to the underlying Beinisvørð Formation, a thick laterally extensive layer of subaerial basalt sheet lobes; (iii) a low velocity layer at 2.5-7.0 km depth beneath the Beinisvørð Formation, which is consistent with hyaloclastites of the Lopra Formation; (iv) an upper basement layer between depths of 5-9 km and characterized by S wave velocities of approximately 3.2 km/s, consistent with low-grade metamorphosed sedimentary rocks; (v) a high velocity basement, with S wave velocities in excess of 3.6 km/s. This likely reflects the presence of a crystalline mid-lower crust of Archaean continental origin. Compared to previous interpretations of the geological structure beneath the Faroe Islands, our new results point to a more structurally complex and laterally heterogeneous crust, and provide constraints which may help to understand how continental fragments are rifted from the

  16. A statistical assessment of seismic models of the U.S. continental crust using Bayesian inversion of ambient noise surface wave dispersion data

    Science.gov (United States)

    Olugboji, T. M.; Lekic, V.; McDonough, W.

    2017-07-01

    We present a new approach for evaluating existing crustal models using ambient noise data sets and its associated uncertainties. We use a transdimensional hierarchical Bayesian inversion approach to invert ambient noise surface wave phase dispersion maps for Love and Rayleigh waves using measurements obtained from Ekström (2014). Spatiospectral analysis shows that our results are comparable to a linear least squares inverse approach (except at higher harmonic degrees), but the procedure has additional advantages: (1) it yields an autoadaptive parameterization that follows Earth structure without making restricting assumptions on model resolution (regularization or damping) and data errors; (2) it can recover non-Gaussian phase velocity probability distributions while quantifying the sources of uncertainties in the data measurements and modeling procedure; and (3) it enables statistical assessments of different crustal models (e.g., CRUST1.0, LITHO1.0, and NACr14) using variable resolution residual and standard deviation maps estimated from the ensemble. These assessments show that in the stable old crust of the Archean, the misfits are statistically negligible, requiring no significant update to crustal models from the ambient noise data set. In other regions of the U.S., significant updates to regionalization and crustal structure are expected especially in the shallow sedimentary basins and the tectonically active regions, where the differences between model predictions and data are statistically significant.

  17. Structure of magma reservoirs beneath Merapi and surrounding volcanic centers of Central Java modeled from ambient noise tomography

    Science.gov (United States)

    Koulakov, Ivan; Maksotova, Gulzhamal; Jaxybulatov, Kayrly; Kasatkina, Ekaterina; Shapiro, Nikolai M.; Luehr, Birger-G.; El Khrepy, Sami; Al-Arifi, Nassir

    2016-10-01

    We present a three-dimensional model of the distribution of S-wave velocity in the upper crust to a depth of 20 km beneath Central Java based on the analysis of seismic ambient noise data recorded by more than 100 seismic stations in 2004 associated with the MERAMEX project. To invert the Rayleigh wave dispersion curves to construct 2-D group-velocity maps and 3-D distributions of S-wave velocity, we have used a new tomographic algorithm based on iterative linearized inversion. We have performed a series of synthetic tests that demonstrate significantly higher resolution in the upper crust with this model compared to the local earthquake travel-time tomography (LET) model previously applied for the same station network. Beneath the southern flank of Merapi, we identify a large low-velocity anomaly that can be split into two layers. The upper layer reflects the ˜1 km thick sedimentary cover of volcanoclastic deposits. The deeper anomaly at depths of ˜4-8 km may represent a magma reservoir with partially molten rock that feeds several volcanoes in Central Java. Beneath the Merapi summit, we observe another low-velocity anomaly as deep as 8 km that may be associated with the active magma reservoir that feeds the eruptive activity of Merapi. In the southern portion of the study area, in the lower crust, we identify a low-velocity anomaly that may represent the top of the pathways of volatiles and melts ascending from the slab that was previously inferred from the LET model results. We observe that this anomaly is clearly separate from the felsic magma reservoirs in the upper crust.

  18. 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.

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

    Science.gov (United States)

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

    2017-02-01

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

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

  2. Surface wave group velocity in the Osaka sedimentary basin, Japan, estimated using ambient noise cross-correlation functions

    Science.gov (United States)

    Asano, Kimiyuki; Iwata, Tomotaka; Sekiguchi, Haruko; Somei, Kazuhiro; Miyakoshi, Ken; Aoi, Shin; Kunugi, Takashi

    2017-08-01

    Inter-station cross-correlation functions estimated using continuous ambient noise or microtremor records were used to extract the seismic wave propagation characteristics of the Osaka sedimentary basin, Japan. Temporary continuous observations were conducted at 15 sites in the Osaka basin between 2011 and 2013. The data were analyzed using seismic interferometry. The target period range was 2-8 s. Cross-correlations between all of the possible station pairs were calculated and stacked to produce a year-long data set, and Rayleigh wave signals in the vertical and radial components and Love wave signals in the transverse component were identified from the results. Simulation of inter-station Green's functions using the finite difference method was conducted to check the performance of the current three-dimensional velocity structure model. The measured time lag between the observed and theoretical Green's functions was less than 2 s for most station pairs, which is less than the wave period of interest in the target frequency range. Group velocity tomography was applied to group delay times estimated by means of multiple filter analysis. The estimated group velocities for longer periods of 5-8 s exhibited spatial variation within the basin, which is consistent with the bedrock depth distribution; however, the group velocities for shorter periods of 2-3 s were almost constant over the studied area. The waveform and group velocity information obtained by seismic interferometry analysis can be useful for future reconstruction of a three-dimensional velocity structure model in the Osaka basin.[Figure not available: see fulltext.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-10-18

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

  4. Wind-generator influence to the power quality in the coupling point to the distribution network

    Directory of Open Access Journals (Sweden)

    Kostić Branka B.

    2011-01-01

    Full Text Available The paper presents the results of analysis of wind-generator and their influence to the power quality parameters in the coupling point to the distribution network. The specified results should be used as a starting point for distribution system operators (DSO for issuing permit for connecting renewable sources, mainly for wind-generators. As the case study, the results of measurements at the only one wind generator installed in Serbia, near town of Tutin, are used. The cases of wind-generator start and stop during low wind and consequently smaller value of the energy delivered to the network are particularly analyzed. Taking into consideration that law regulations in this field are not yet defined, EU standards and guidelines are used along with the newly adopted Technical recommendation No. 16 of Public Enterprise Electric Power Industry of Serbia.

  5. Influence of the characteristic and installation site of wind generator on quantity of produced energy

    International Nuclear Information System (INIS)

    Palge, V.; Lepa, J.; Tamm, T.

    2002-01-01

    In Estonia, especially in inland the wind speed is rather low. According to the Master thesis of Tonis Tamm the opportunities of use of several types of wind generators are analysed. It is found out, that the wind generator, beginning to produce energy at wind speed 2 m/s can in such conditions produce about four times more electricity energy than such having 'cut-in' wind speed 4 m/s. (author)

  6. 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.

  7. 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

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

    Science.gov (United States)

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

    2017-08-01

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

  9. 3D structures of crust and uppermost mantle and azimuthal anisotropy in Tibet and surrounding regions from ambient noise tomography

    Science.gov (United States)

    Yang, Y.; Zheng, Y.; Ritzwoller, M. H.

    2010-12-01

    Tibet is our planet’s natural laboratory for studying how continents interact and deform in response to the collision between the Indian and the Eurasian plates. Although numerous seismic studies of Tibet have been performed, there remain fundamental disagreements in first-order questions about crustal deformation; e.g., whether the crust deforms coherently vertically or is perhaps coupled to the mantle. The reason is that existing models either do not model the crust effectively or only model the crust beneath parts of Tibet due to limitations in the distribution of seismic stations. In this study, we have applied ambient noise tomography (ANT) to data from FDSN stations, several temporary US PASSCAL installations and the Chinese provincial networks in and around Tibet during 2003 to 2009. Inter-station Rayleigh wave dispersion curves are measured from cross correlations of vertical components. These dispersion measurements are used to invert for isotropic phase velocity maps and azimuthal anisotropy of Rayleigh waves. Major basins, including Tarim, Qadaim and Sichuan, are all well delineated by slow phase velocities at short periods (8-15 sec). Crustal thinning from Tibet to the surrounding regions is manifest as a phase velocity increase at periods from 25 to 40 sec. Resulting phase velocity maps are further inverted for 3D Vs structures of crust and uppermost mantle. Low velocities are observed across most of the Tibetan Plateau at the depth range of 20-50 km. In southeastern Tibet, low velocities extend to the Yunnan Plateau while, in northeastern Tibet, low velocities are confined to the Plateau region and there is no low velocity existing beneath the Qingling Orogen between the Ordos Block and the Sichuan Basin in the crust and uppermost mantle. Prominent high velocities are observed in the middle and lower crust and in the uppermost mantle beneath the Tarim Basin, the Ordos Block and the Sichuan Basin. Patterns of Rayleigh wave azimuthal anisotropy at

  10. 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 (<30 km depth). ANT will be used to estimate the depth of basins in the northern Altiplano, and aid in constraining the upper crustal shear wave velocities for improved migration of receiver functions to depth. 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.

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  12. The Effects of Ambient Shipping Noise on the Performance of Single and Multiple Channel Moment Detectors for Unknown Transient Signals

    National Research Council Canada - National Science Library

    Pflug, Lisa

    1998-01-01

    ...) detector in both the Gaussian noise and the measured noise. Although the application of one-dimensional passband filters before the moment calculations improves the performance of all three detectors, it induces additional detection gain for the higher order moment detectors.

  13. Impact of wind generation on the operation and development of the UK electricity systems

    International Nuclear Information System (INIS)

    Strbac, Goran; Shakoor, Anser; Pudjianto, Danny; Black, Mary; Bopp, Thomas

    2007-01-01

    Although penetration of wind generation may displace a significant amount of energy produced by large conventional plant, there are issues associated with the extent to which wind generation will be able to replace the capacity and flexibility of conventional generating plant. This is important since wind power is variable, so it will be necessary to retain a significant proportion of conventional plant to ensure security of supply especially under conditions of high demand and low wind. Hence, the capacity value of wind generation will be limited as it will not be possible to displace conventional generation capacity on a ''megawatt for megawatt'' basis. Wind power is variable and not easy to predict, hence various forms of additional reserves will be needed to maintain the balance between supply and demand at all times. Additionally, if the majority of wind generation plant is located in Scotland and the North of England, reinforcement of the transmission network will be needed to accommodate the increases in the north-south flow of electricity. In this paper an assessment of the costs and benefits of wind generation on the UK electricity system is carried out, assuming different levels of wind power capacity. Overall, it is concluded that the system will be able to accommodate significant increases in wind power generation with relatively small increases in overall costs of supply, about 5% of the current domestic electricity price in case of 20% energy produced by wind power. (author)

  14. 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.

  15. Trading wind generation from short-term probabilistic forecasts of wind power

    DEFF Research Database (Denmark)

    Pinson, Pierre; Chevallier, Christophe; Kariniotakis, Georges

    2007-01-01

    Due to the fluctuating nature of the wind resource, a wind power producer participating in a liberalized electricity market is subject to penalties related to regulation costs. Accurate forecasts of wind generation are therefore paramount for reducing such penalties and thus maximizing revenue...... participation. Such strategies permit to further increase revenues and thus enhance competitiveness of wind generation compared to other forms of dispatchable generation. This paper formulates a general methodology for deriving optimal bidding strategies based on probabilistic forecasts of wind generation....... Despite the fact that increasing accuracy in spot forecasts may reduce penalties, this paper shows that, if such forecasts are accompanied with information on their uncertainty, i.e., in the form of predictive distributions, then this can be the basis for defining advanced strategies for market...

  16. Combined hydro-wind generation bids in a pool-based electricity market

    International Nuclear Information System (INIS)

    Angarita, Jorge L.; Usaola, Julio; Martinez-Crespo, Jorge

    2009-01-01

    Present regulatory trends are promoting the direct participation of wind energy in electricity markets. The final result of these markets sets the production scheduling for the operation time, including a power commitment from the wind generators. However, wind resources are uncertain, and the final power delivered usually differs from the initial power committed. This imbalance produces an overcost in the system, which must be paid by those who produce it, e.g., wind generators among others. As a result, wind farm revenue decreases, but it could increase by allowing wind farms to submit their bids to the markets together with a hydro generating unit, which may easily modify its production according to the expected imbalance. This paper presents a stochastic optimization technique that maximizes the joint profit of hydro and wind generators in a pool-based electricity market, taking into account the uncertainty of wind power prediction. (author)

  17. Estimating the impact of wind generation and wind forecast errors on energy prices and costs in Ireland

    OpenAIRE

    Swinand, Gregory P; O'Mahoney, Amy

    2014-01-01

    This paper studies the impact of wind generation on system costs and prices in Ireland. The need to mitigate climate change, achieve renewables energy targets, and use renewable sources of energy means that many countries are considering greater levels of wind generation in their power generation mix. The overall impact of wind generation on system costs and performance has only been studied recently, and often with limited actual data from power systems with increased wind penetration. The p...

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

    Directory of Open Access Journals (Sweden)

    Alissa R. Petrelli

    2017-06-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

  1. Annoyance rating of wind turbine noise

    International Nuclear Information System (INIS)

    Iredale, R.A.

    1992-01-01

    This paper proposes a simple criterion for noise limitation of wind turbines: 'The La A50 from a Wind Farm should not exceeding the L A50 of the wind generated background plus 5dB at any place of potential complaint'. This criterion is then examined and developed in the light of experience to date with turbine noise complaint and procedures. (author)

  2. Power control for direct-driven permanent magnet wind generator system with battery storage.

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient.

  3. Incorporation of a Wind Generator Model into a Dynamic Power Flow Analysis

    Directory of Open Access Journals (Sweden)

    Angeles-Camacho C.

    2011-07-01

    Full Text Available Wind energy is nowadays one of the most cost-effective and practical options for electric generation from renewable resources. However, increased penetration of wind generation causes the power networks to be more depend on, and vulnerable to, the varying wind speed. Modeling is a tool which can provide valuable information about the interaction between wind farms and the power network to which they are connected. This paper develops a realistic characterization of a wind generator. The wind generator model is incorporated into an algorithm to investigate its contribution to the stability of the power network in the time domain. The tool obtained is termed dynamic power flow. The wind generator model takes on account the wind speed and the reactive power consumption by induction generators. Dynamic power flow analysis is carried-out using real wind data at 10-minute time intervals collected for one meteorological station. The generation injected at one point into the network provides active power locally and is found to reduce global power losses. However, the power supplied is time-varying and causes fluctuations in voltage magnitude and power fl ows in transmission lines.

  4. Simulation of an Underwater Acoustic Communication Channel Characterized by Wind-Generated Surface Waves and Bubbles

    NARCIS (Netherlands)

    Dol, H.S.; Colin, M.E.G.D.; Ainslie, M.A.; Walree, P.A. van; Janmaat, J.

    2013-01-01

    Abstract—Sea-surface scattering by wind-generated waves and bubbles is regarded to be the main nonplatform related cause of the time variability of shallow acoustic communication channels. Simulations for predicting the quality of acoustic communication links in such channels thus require adequate

  5. Simulation of an Underwater Acoustic Communication Channel Characterized by Wind-Generated Surface Waves and Bubbles

    NARCIS (Netherlands)

    Dol, H.S.; Ainslie, M.A.; Colin, M.E.G.D.; Janmaat, J.

    2012-01-01

    Sea surface scattering by wind-generated waves and bubbles is regarded to be the main nonplatform-related cause of the time variability of shallow acoustic communication channels. Simulations for predicting the quality of acoustic communication links in such channels thus require adequate modelling

  6. Wind generator based on cascade connection of two asynchronized synchronous machines

    International Nuclear Information System (INIS)

    Dzhagarov, N.; Dzhagarova, Yu.

    2000-01-01

    A model of a wind generator with two asynchronized synchronous machines presented and different regimes are investigated. The analysis shows that the suggested scheme of a brushless generator works and has more advantages (reliability, easy for operation) in comparison with the known ones

  7. Power Control for Direct-Driven Permanent Magnet Wind Generator System with Battery Storage

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient. PMID:25050405

  8. FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM

    Science.gov (United States)

    The paper describes a variable-speed wind generation system where fuzzy logic principles are used to optimize efficiency and enhance performance control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which either pump...

  9. Operational performance of the Avispa-IIE wind generator in microhybrid systems

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Galarza, Raul; Mejia Neri, Fortino [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1997-12-31

    The purpose of this paper is to make a general analysis over the operational performance of the Avispa-IIE wind generator in an Solar-Eolic hybrid installation, at an eco-tourist resort. This work was performed through the monitor of the wind generator and the system itself throughout a year, for the acquisition taking the variables of interest and operational parameters that might allow to characterize and to evaluate the general behavior of the system. Herein are the principals characteristics of the wind generator; its performance curve, the basic configuration of the installation and the control philosophy; Likewise, some technical and human problems which arise during the operation of the system are included, the implementation of improvements in the wind generator and the general results acquired during the time of operation of the wind generator in the cited installations. [Espanol] El proposito de este articulo es el hacer un analisis general del comportamiento operacional del aerogenerador Avispa-IIE en una instalacion hibrida Solar-Eolica en un lugar de veraneo eco-turistico. Este trabajo ha sido llevado a cabo mediante el monitor del aerogenerador y el sistema mismo por espacio de un ano, para la adquisicion de las variables de interes y de los parametros operacionales que pudieran servir para caracterizar y evaluar el comportamiento general del sistema. Aqui se incluyen las caracteristicas principales del aerogenerador; su curva de comportamiento, la configuracion basica de la instalacion y la filosofia del control. De la misma manera se incluyen algunos problemas tecnicos y humanos que se originan durante la operacion del sistema y la puesta en practica de las mejoras del aerogenerador y los resultados generales adquiridos durante el tiempo de operacion del aerogenerador en las instalaciones citadas.

  10. Assessing the value of wind generation in future carbon constrained electricity industries

    International Nuclear Information System (INIS)

    Vithayasrichareon, Peerapat; MacGill, Iain F.

    2013-01-01

    This paper employs a novel Monte-Carlo based generation portfolio assessment tool to explore the implications of increasing wind penetration and carbon prices within future electricity generation portfolios under considerable uncertainty. This tool combines optimal generation mix techniques with Monte Carlo simulation and portfolio analysis methods to determine expected overall generation costs, associated cost uncertainty and expected CO 2 emissions for different possible generation portfolios. A case study of an electricity industry with coal, Combined Cycle Gas Turbines (CCGT), Open Cycle Gas Turbines (OCGT) and wind generation options that faces uncertain future fossil-fuel prices, carbon pricing, electricity demand and plant construction costs is presented to illustrate some of the key issues associated with growing wind penetrations. The case study uses half-hourly demand and wind generation data from South Eastern Australia, and regional estimates of new-build plant costs and characteristics. Results suggest that although wind generation generally increases overall industry costs, it reduces associated cost uncertainties and CO 2 emissions. However, there are some cases in which wind generation can reduce the overall costs of generation portfolios. The extent to which wind penetration affects industry expected costs and uncertainties depends on the level of carbon price and the conventional technology mix in the portfolios. - Highlights: ► A probabilistic portfolio analysis tool to assess generation portfolios with wind power. ► Explore the impacts of wind penetrations and carbon prices under uncertainties. ► Wind generation increases overall portfolio costs but reduces cost risks and emissions. ► The value of wind power depends on the carbon price and the technology mix. ► Complex interactions between wind penetration level and carbon pricing.

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

    Science.gov (United States)

    Jakovlev, Andrey; Kaviani, Ayoub; Ruempker, Georg

    2017-04-01

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

  12. Three essays on the effect of wind generation on power system planning and operations

    Science.gov (United States)

    Davis, Clay Duane

    While the benefits of wind generation are well known, some drawbacks are still being understood as wind power is integrated into the power grid at increasing levels. The primary difference between wind generation and other forms of generation is the intermittent, and somewhat unpredictable, aspect of this resource. The somewhat uncontrollable aspect of wind generation makes it important to consider the relationship between this resource and load, and also how the operation of other non-wind generation resources may be affected. The three essays that comprise this dissertation focus on these and other important issues related to wind generation; leading to an improved understanding of how to better plan for and utilize this resource. The first essay addresses the cost of increased levels of installed wind capacity from both a capacity planning and economic dispatch perspective to arrive at the total system cost of installing a unit of wind capacity. This total includes not only the cost of the wind turbine and associated infrastructure, but also the cost impact an additional unit of wind capacity has on the optimal mix and operation of other generating units in the electricity supply portfolio. The results of the model showed that for all wind expansion scenarios, wind capacity is not cost-effective regardless of the level of the wind production tax credit and carbon prices that were considered. Larger levels of installed wind capacity result in reduced variable cost, but this reduction is not able to offset increases in capital cost, as a unit of installed wind capacity does not result in an equal reduction in other non-wind capacity needs. The second essay develops a methodology to better handle unexpected short term fluctuations in wind generation within the existing power system. The methodology developed in this essay leads to lower expected costs by anticipating and planning for fluctuations in wind generation by focusing on key constraints in the system. The

  13. Joint inversion of teleseismic P waveforms and surface-wave group velocities from ambient seismic noise in the Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Růžek, Bohuslav; Plomerová, Jaroslava; Babuška, Vladislav

    2012-01-01

    Roč. 56, č. 1 (2012), s. 107-140 ISSN 0039-3169 R&D Projects: GA ČR GA205/07/1088; GA AV ČR IAA300120709; GA MŠk LM2010008 Institutional research plan: CEZ:AV0Z30120515 Keywords : receiver function * seismic noise * joint inversion * Bohemian Massif * velocity structure Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.975, year: 2012

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

    Science.gov (United States)

    Yan, Peng; Li, Zhiwei; Li, Fei; Yang, Yuande; Hao, Weifeng; Bao, Feng

    2018-03-01

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

  16. Effect of broadband-noise masking on the behavioral response of a harbor porpoise (Phocoena phocoena) to 1-s duration 6-7 kHz sonar up-sweeps.

    Science.gov (United States)

    Kastelein, Ronald A; Steen, Nele; de Jong, Christ; Wensveen, Paul J; Verboom, Willem C

    2011-04-01

    Naval sonar systems produce signals which may affect the behavior of harbor porpoises, though their effect may be reduced by ambient noise. To show how natural ambient noise influences the effect of sonar sweeps on porpoises, a porpoise in a pool was exposed to 1-s duration up-sweeps, similar in frequency range (6-7 kHz) to those of existing naval sonar systems. The sweep signals had randomly generated sweep intervals of 3-7 s (duty cycle: 19%). Behavioral parameters during exposure to signals were compared to those during baseline periods. The sessions were conducted under five background noise conditions: the local normal ambient noise and four conditions mimicking the spectra for wind-generated noise at Sea States 2-8. In all conditions, the sweeps caused the porpoise to swim further away from the transducer, surface more often, swim faster, and breathe more forcefully than during the baseline periods. However, the higher the background noise level, the smaller the effects of the sweeps on the surfacing behavior of the porpoise. Therefore, the effects of naval sonar systems on harbor porpoises are determined not only by the received level of the signals and the hearing sensitivity of the animals but also by the background noise.

  17. Surface wave imaging of the weakly extended Malawi Rift from ambient-noise and teleseismic Rayleigh waves from onshore and lake-bottom seismometers

    Science.gov (United States)

    Accardo, N. J.; Gaherty, J. B.; Shillington, D. J.; Ebinger, C. J.; Nyblade, A. A.; Mbogoni, G. J.; Chindandali, P. R. N.; Ferdinand, R. W.; Mulibo, G. D.; Kamihanda, G.; Keir, D.; Scholz, C.; Selway, K.; O'Donnell, J. P.; Tepp, G.; Gallacher, R.; Mtelela, K.; Salima, J.; Mruma, A.

    2017-06-01

    Located at the southernmost sector of the Western Branch of the East African Rift System, the Malawi Rift exemplifies an active, magma-poor, weakly extended continental rift. To investigate the controls on rifting, we image crustal and uppermost mantle structure beneath the region using ambient-noise and teleseismic Rayleigh-wave phase velocities between 9 and 100 s period. Our study includes six lake-bottom seismometers located in Lake Malawi (Nyasa), the first time seismometers have been deployed in any of the African rift lakes. Noise levels in the lake are lower than that of shallow oceanic environments and allow successful application of compliance corrections and instrument orientation determination. Resulting phase-velocity maps reveal slow velocities primarily confined to Lake Malawi at short periods (T 25 s), a prominent low-velocity anomaly exists beneath the Rungwe Volcanic Province at the northern terminus of the rift basin. Estimates of phase-velocity sensitivity indicates these low velocities occur within the lithospheric mantle and potentially uppermost asthenosphere, suggesting that mantle processes may control the association of volcanic centres and the localization of magmatism. Beneath the main portion of the Malawi Rift, a modest reduction in velocity is also observed at periods sensitive to the crust and upper mantle, but these velocities are much higher than those observed beneath Rungwe.

  18. Improving Low Voltage Ride Through Capability of Wind Generators Using Dynamic Voltage Restorer

    Science.gov (United States)

    Sivasankar, Gangatharan; Suresh Kumar, Velu

    2014-08-01

    The increasing wind power integration with power grid has forced the situation to improve the reliability of wind generators for stable operation. One important problem with induction generator based wind farm is its low ride through capability to the grid voltage disturbance. Any disturbance such as voltage dip may cause wind farm outages. Since wind power contribution is in predominant percentage, such outages may lead to stability problem. The proposed strategy is to use dynamic voltage controller (DVR) to compensate the voltage disturbance. The DVR provides the wind generator the ability to remain connected in grid and improve the reliability. The voltage dips due to symmetrical and unsymmetrical faults are considered for analysis. The vector control scheme is employed for fault compensation which uses software phase locked loop scheme and park dq0 transformation technique. Extensive simulation results are included to illustrate the control and operation of DVR.

  19. Robust optimization-based DC optimal power flow for managing wind generation uncertainty

    Science.gov (United States)

    Boonchuay, Chanwit; Tomsovic, Kevin; Li, Fangxing; Ongsakul, Weerakorn

    2012-11-01

    Integrating wind generation into the wider grid causes a number of challenges to traditional power system operation. Given the relatively large wind forecast errors, congestion management tools based on optimal power flow (OPF) need to be improved. In this paper, a robust optimization (RO)-based DCOPF is proposed to determine the optimal generation dispatch and locational marginal prices (LMPs) for a day-ahead competitive electricity market considering the risk of dispatch cost variation. The basic concept is to use the dispatch to hedge against the possibility of reduced or increased wind generation. The proposed RO-based DCOPF is compared with a stochastic non-linear programming (SNP) approach on a modified PJM 5-bus system. Primary test results show that the proposed DCOPF model can provide lower dispatch cost than the SNP approach.

  20. Models for Numerical Evaluation of Variable Speed Different Wind Generator Systems

    DEFF Research Database (Denmark)

    Li, Hui; Chen, Zhe; Polinder, H.

    2007-01-01

    -effective wind conversion system among the various possible configurations. The aim of this project is to evaluate the suitable cost- effective wind generator systems by using the optimization designs and the numerical comparison. The research report is made of two parts, one focus on the design models......, the analytical models include the wind turbine power characteristics; the single/threestage gearbox and the power electronic converter for possible wind turbine concepts are described. Finally, the electromagnetic design models of the investigated generator topologies are presented, including the squirrel cage...... induction generator (SCIG), the doubly-fed induction generator (DFIG), the electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). Numerical evaluation with optimized design and comparison of variable speed wind generator systems by using the presented models...

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

    Science.gov (United States)

    Sadeghisorkhani, Hamzeh; Gudmundsson, Ólafur; Tryggvason, Ari

    2018-01-01

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

  2. A comparative investigation of three PM-less MW power range wind generator topologies

    DEFF Research Database (Denmark)

    Bratiloveanu, Catalin-Rauti; Traian Cosmin Anghelus, Dumitru; Boldea, I.

    2012-01-01

    investigates by quasi 2D-FEM two dc stator polarized (to increase machine side PWM converter voltage utilization, that is to reduce peak kVA ratings and costs of the machine side PWM converter) directly-driven switched reluctance generators (one with circumferential field and one with transverse flux (with......-less topology are required before declaring them fit for industrial wind generators....

  3. Rating Requirements of the UPQC to Integrate the FSIG Type Wind Generation to the Grid

    OpenAIRE

    Jayanti, N.; Basu, Malabika; Conlon, Michael; Gaughan, Kevin

    2009-01-01

    The ability of wind generation to remain connected to the grid in the event of system faults and dynamic reactive power compensation are two aspects of grid integration, which have received particular attention. The wind driven, fixed-speed induction generator (FSIG) on its own fails to fulfil these requirements of grid integration. The application of a unified power quality conditioner (UPQC) to overcome the grid integration problems of the FSIG is investigated. The role of the UPQC in enhan...

  4. An experimental study of the surface elevation probability distribution and statistics of wind-generated waves

    Science.gov (United States)

    Huang, N. E.; Long, S. R.

    1980-01-01

    Laboratory experiments were performed to measure the surface elevation probability density function and associated statistical properties for a wind-generated wave field. The laboratory data along with some limited field data were compared. The statistical properties of the surface elevation were processed for comparison with the results derived from the Longuet-Higgins (1963) theory. It is found that, even for the highly non-Gaussian cases, the distribution function proposed by Longuet-Higgins still gives good approximations.

  5. Small wind generators for battery charging in Peru and Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    Dunnett, S. [Intermediate Technology Development Group, Rugby (United Kingdom)

    2000-07-01

    The Intermediate Technology Development Group (ITDG) have developed a small wind generator (SWG) intended primarily for battery charging in Peru and Sri Lanka. The project is funded mainly by the Department for International Development (DfID) and aims to provide rural households and communities who do not have access to mains electricity with a form of electrification. This paper reports on progress to date and is correct at the time of going to press, but subsequent changes to specifications may occur. (Author)

  6. A Fault Diagnostic Method for Position Sensor of Switched Reluctance Wind Generator

    DEFF Research Database (Denmark)

    Wang, Chao; Liu, Xiao; Liu, Hui

    2016-01-01

    Fast and accurate fault diagnosis of the position sensor is of great significance to ensure the reliability as well as sensor fault tolerant operation of the Switched Reluctance Wind Generator (SRWG). This paper presents a fault diagnostic scheme for a SRWG based on the residual between the estim...... conditions. The results provide a feasible theoretical and technical basis for the effective condition monitoring and predictive maintenance of SRWG....

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

    Science.gov (United States)

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

    2017-12-01

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

  8. Capacity Value of PV and Wind Generation in the NV Energy System

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Shuai; Diao, Ruisheng; Samaan, Nader A.; Etingov, Pavel V.

    2014-03-21

    Calculation of photovoltaic (PV) and wind power capacity values is important for estimating additional load that can be served by new PV or wind installations in the electrical power system. It also is the basis for assigning capacity credit payments in systems with markets. Because of variability in solar and wind resources, PV and wind generation contribute to power system resource adequacy differently from conventional generation. Many different approaches to calculating PV and wind generation capacity values have been used by utilities and transmission operators. Using the NV Energy system as a study case, this report applies peak-period capacity factor (PPCF) and effective load carrying capability (ELCC) methods to calculate capacity values for renewable energy sources. We show the connection between the PPCF and ELCC methods in the process of deriving a simplified approach that approximates the ELCC method. This simplified approach does not require generation fleet data and provides the theoretical basis for a quick check on capacity value results of PV and wind generation. The diminishing return of capacity benefit as renewable generation increases is conveniently explained using the simplified capacity value approach.

  9. 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

  10. A Trial for Detecting the Temporal Variation in Seismic Velocity Accompanied by a Slow Slip Event using Seismic Interferometry of Ambient Noise

    Science.gov (United States)

    Uemura, Miyuu; Ito, Yoshihiro; Ohta, Kazuaki; Hino, Ryota; Shinohara, Masanao

    2017-04-01

    Seismic interferometry is one of the most effective techniques to detect temporal variations in seismic velocity before or after a large earthquake. Some previous studies have been reported on seismic velocity reduction due to the occurrence of large earthquakes (e.g., Wegler et al., 2009; Yamada et al., 2010) as well as preceding them (e.g., Lockner et al., 1977; Yoshimitsu et al., 2009). However, there have only been a few studies thus far which attempt to detect seismic velocity changes associated with slow slip events (SSEs). In this study, we focus on applying seismic interferometry to ambient noise data from ocean bottom seismometers (OBSs) deployed near a subduction zone. Between the end of January 2011 and the largest foreshock occurring on March 9th that precedes the March 11, 2011 Tohoku-Oki earthquake, SSEs and low-frequency tremors were detected offshore Miyagi Prefecture (Ito et al., 2013, 2015; Katakami et al., 2016). We applied our seismic interferometry analysis using ambient noise to recordings from 17 OBS stations that were installed in the vicinity of the 2011 Tohoku-Oki earthquake source region, and only considered the recordings from before that major earthquake. All the OBSs are short-period seismometers with three components which have an eigenfrequency of 4.5 Hz. These OBSs were deployed offshore Miyagi Prefecture between November 2010 and April 2011. Before proceeding with the seismic interferometry analysis, we needed to estimate the two horizontal components of the original deployment orientation for 13 OBSs in (we could not estimate them for 4 OBSs). To obtain the OBS orientation, we used particle orbits of some direct P waves from selected tectonic earthquakes, in order to extract one vertical and two horizontal components. Then, the seismic interferometry analysis consisted of the following steps. First, we applied a band-pass filter of 0.25-2.0 Hz and one-bit technique to the ambient noise signal. Second, we calculated auto

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

    Science.gov (United States)

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

    2013-12-01

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

  12. Integrating ambient noise with GIS for a new perspective on volcano imaging and monitoring: The case study of Mt. Etna

    Science.gov (United States)

    Guardo, R.; De Siena, L.

    2017-11-01

    The timely estimation of short- and long-term volcanic hazard relies on the availability of detailed 3D geophysical images of volcanic structures. High-resolution seismic models of the absorbing uppermost conduit systems and highly-heterogeneous shallowest volcanic layers, while particularly challenging to obtain, provide important data to locate feasible eruptive centres and forecast flank collapses and lava ascending paths. Here, we model the volcanic structures of Mt. Etna (Sicily, Italy) and its outskirts using the Horizontal to Vertical Spectral Ratio method, generally applied to industrial and engineering settings. The integration of this technique with Web-based Geographic Information System improves precision during the acquisition phase. It also integrates geological and geophysical visualization of 3D surface and subsurface structures in a queryable environment representing their exact three-dimensional geographic position, enhancing interpretation. The results show high-resolution 3D images of the shallowest volcanic and feeding systems, which complement (1) deeper seismic tomography imaging and (2) the results of recent remote sensing imaging. The study recovers a vertical structure that divides the pre-existing volcanic complexes of Ellittico and Cuvigghiuni. This could be interpreted as a transitional phase between the two systems. A comparison with recent remote sensing and geological results, however, shows that anomalies are generally related to volcano-tectonic structures active during the last 17 years. We infer that seismic noise measurements from miniaturized instruments, when combined with remote sensing techniques, represent an important resource to monitor volcanoes in unrest, reducing the risk of loss of human lives and instrumentation.

  13. Engineering geological zonation of a complex landslide system through seismic ambient noise measurements at the Selmun Promontory (Malta)

    Science.gov (United States)

    Iannucci, Roberto; Martino, Salvatore; Paciello, Antonella; D'Amico, Sebastiano; Galea, Pauline

    2018-01-01

    The cliff slope of the Selmun Promontory, located in the Northern part of the island of Malta (Central Mediterranean Sea) close to the coastline, is involved in a landslide process as exhibited by the large block-size talus at its bottom. The landslide process is related to the geological succession outcropping in the Selmun area, characterised by the over-position of a grained limestone on a plastic clay, that induces a lateral spreading phenomenon associated with detachment and collapse of different-size rock blocks. The landslide process shapes a typical landscape with a stable plateau of stiff limestone bordered by an unstable cliff slope. The ruins of Għajn Ħadid Tower, the first of the thirteen watchtowers built in 1658 by the Grand Master Martin de Redin, stand out on the Selmun Promontory. The conservation of this important heritage site, already damaged by an earthquake which struck the Maltese Archipelago on October 12th 1856, is currently threatened by a progressive retreat of the landslide process towards the inland plateau area. During 2015 and 2016, field surveys were carried out to derive an engineering geological model of the Selmun Promontory. After a high-resolution geomechanical survey, the spatial distribution of the joints affecting the limestone was obtained. At the same time, 116 single-station noise measurements were carried out to cover the inland and edge plateau zones as well as the clayey slope area. The obtained 1-hour time histories were analysed through the horizontal to vertical spectral ratio (HVSR) technique, as well as polarity and ellipticity analysis of particle motion to define the local seismic response in zones having different stability conditions, i.e. related to the presence of unstable rock blocks characterised by different vibrational modes. The results obtained confirm the suitability of passive seismic geophysical techniques for zoning landslide hazard in case of rock slopes and demonstrate the relevance of

  14. Characterisation of Large Disturbance Rotor Angle and Voltage Stability in Interconnected Power Networks with Distributed Wind Generation

    OpenAIRE

    Meegahapola, Lasantha; Littler, Timothy

    2015-01-01

    Wind generation in highly interconnected power networks creates local and centralised stability issues based on their proximity to conventional synchronous generators and load centres. This paper examines the large disturbance stability issues (i.e. rotor angle and voltage stability) in power networks with geographically distributed wind resources in the context of a number of dispatch scenarios based on profiles of historical wind generation for a real power network. Stability issues have be...

  15. Potential for increased wind-generated electricity utilization using heat pumps in urban areas

    International Nuclear Information System (INIS)

    Waite, Michael; Modi, Vijay

    2014-01-01

    Highlights: • Large-scale wind power and increased electric heat pumps were evaluated. • A deterministic model of wind power and electricity demand was developed. • Sub-models for space heating and domestic hot water demand were developed. • Increased use of heat pumps can improve the viability of large-scale wind power. • Larger wind power capacity can meet a target utilization rate with more heat pumps. - Abstract: The U.S. has substantial wind power potential, but given wind’s intermittent availability and misalignment with electricity demand profiles, large-scale deployment of wind turbines could result in high electricity costs due to energy storage requirements or low utilization rates. While fuel switching and heat pumps have been proposed as greenhouse gas (GHG) emissions and energy reduction strategies at the building scale, this paper shows that heat pump adoption could have additional system-wide benefits by increasing the utilization of wind-generated electricity. A model was developed to evaluate the effects of coupling large-scale wind power installations in New York State with increased use of electric heat pumps to meet a portion of space heating and domestic hot water (DHW) demands in New York City. The analysis showed significant increases in wind-generated electricity utilization with increased use of heat pumps, allowing for higher installed capacity of wind power. One scenario indicates that 78.5% annual wind-generated electricity utilization can be achieved with 3 GW of installed wind power capacity generated electricity equal to 20% of existing NYC annual electricity demand; if 20% of space heating and DHW demands are provided by heat pumps, the 78.5% utilization rate can be achieved with an increase of total wind power capacity to 5 GW. Therefore, this integrated supply–demand approach could provide additional system-wide emissions reductions

  16. Determining the impact of wind on system costs via the temporal patterns of load and wind generation

    International Nuclear Information System (INIS)

    Davis, Clay D.; Gotham, Douglas J.; Preckel, Paul V.; Liu, Andrew L.

    2013-01-01

    Ambitious targets have been set for expanding electricity generation from renewable sources, including wind. Expanding wind power impacts needs for other electricity generating resources. As states plan for increasing levels of wind generation in their portfolio of generation resources it is important to consider how this intermittent resource impacts the need for other generation resources. A case study for Indiana estimates the value of wind capacity and demonstrates how to optimize its level and the levels of other generation resources. Changes are driven by temporal patterns of wind power output and load. System wide impacts are calculated for energy, capacity, and costs under multiple wind expansion scenarios which highlight the geographic characteristics of a systems portfolio of wind generation. The impacts of carbon prices, as proposed in the Bingaman Bill, are considered. Finally, calculations showing the effect increasing levels of wind generation will have on end use Indiana retail rates are included. - Highlights: • We estimate the value of wind capacity. • We determine wind generation's impact on the optimal mix of non-wind generation. • Optimal levels of wind and non-wind generation are determined. • We consider the impact of a carbon price on the optimal mix of resources. • The impact of additional wind capacity on Indiana residential rates is calculated

  17. Rotor Position Estimation for Switched Reluctance Wind Generator Using Extreme Learning Machine

    DEFF Research Database (Denmark)

    Wang, Chao; Liu, Xiao; Chen, Zhe

    2014-01-01

    Switched reluctance generator (SRG) is becoming more and more attractive in wind energy applications mainly because of its high fault tolerant ability and high reliability. The position sensor is one of the vulnerable points of the SRG when exposed to harsh environments such as offshore where many...... Reluctance Wind Generator (SRWG) based on Extreme Learning Machine (ELM) which could build a nonlinear mapping between flux linkage-current and rotor position. The learning data are derived from magnetization curves of the SRWG which are obtained from Finite Element Analysis (FEA) of an SRG with 8/6 stator...

  18. Loss Minimizing Operation of Doubly Fed Induction Generator Based Wind Generation Systems Considering Reactive Power Provision

    DEFF Research Database (Denmark)

    Baohua, Zhang; Hu, Weihao; Chen, Zhe

    2014-01-01

    The paper deals with control techniques for minimizing the operating loss of doubly fed induction generator based wind generation systems when providing reactive power. The proposed method achieves its goal through controlling the rotor side q-axis current in the synchronous reference frame....... The formula for the control reference is explicitly deduced in this paper considering the losses of the generator, the power electronic devices and the filter. Three control strategies are compared with the proposed method under different wind speeds and different reactive power references. The simulation...

  19. Analytical Derivation of Electrical-Side Maximum Power Line for Wind Generators

    Directory of Open Access Journals (Sweden)

    Sergei Kolesnik

    2017-09-01

    Full Text Available In order to enhance the maximum power point tracking (MPPT speed of solar generators, offline calculated maximum power line (MPL is often used as a feed-forward signal added to the output of MPPT controller. MPL is nonlinear static electrical characteristic of renewable energy generators connecting all the maximum power points for given temperature. In this letter, electrical side MPL is derived for a typical wind turbine generator (WTG. It is shown that MPLs of solar and wind generators possess similar structure, supporting the similarity between the two energy conversion processes.

  20. Coordinated control of wind generation and energy storage for power system frequency regulation

    Science.gov (United States)

    Baone, Chaitanya Ashok

    Large-scale centralized synchronous generators have long been the primary actors in exercising active power and frequency control, and much of the existing grid control framework is predicated upon their dynamic terminal characteristics. Important among these characteristics is the inertia of such generators. These play key roles in determining the electromechanical stability of the electric power grid. Modern wind generator systems are partially or fully connected to the grid through power electronic interfaces, and hence do not present the same level of inertial coupling. The absence of inertial frequency response from modern wind generator systems is a topic of growing concern in power engineering practice, as the penetration of wind generation is expected to grow dramatically in the next few years. Solutions proposed in the literature have sought to address this problem by seeking to mimic the inherent inertial response characteristics of traditional synchronous generators via control loops added to wind generators. Recent literature has raised concerns regarding this approach, and the work here will further examine its shortcomings, motivating approaches that seek to optimally design for the characteristics of the equipment exercising the control, rather than forcing new technologies to mimic the characteristics of synchronous machines. In particular, this work will develop a new approach to power system frequency regulation, with features suited to distributed energy storage devices such as grid-scale batteries and wind turbine speed and blade pitch control. The dynamic characteristics of these new technologies are treated along with existing mechanisms, such as synchronous machine governor control, to develop a comprehensive multi-input control design approach. To make the method practically feasible for geographically distributed power systems, an observer-based distributed control design utilizing phasor measurement unit (PMU) signals along with local

  1. Floating wind generators offshore wind farm: Implications for structural loads and control actions

    International Nuclear Information System (INIS)

    Garcia, E.; Morant F, Quiles E.; Correcher, A.

    2009-01-01

    This paper describes the work currently carried out in the design of floating wind generators and their involvement in the future development of power generation in marine farms in depths exceeding 20 m. We discuss the main issues to be taken into account in the design of floating platforms, including the involvement of structural loads they bear. Also from a standpoint of control engineering are discussed strategies to reduce structural loads such a system to ensure adequate durability and therefore ensuring their economic viability. Finally, the abstract modeling tools for floating wind turbines that can be used in both structural design and the design of appropriate control algorithms

  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. Low Voltage Ride-through in DFIG Wind Generators by Controlling the Rotor Current without Crowbars

    Directory of Open Access Journals (Sweden)

    Jaime Rodríguez Arribas

    2014-01-01

    Full Text Available Among all the different types of electric wind generators, those that are based on doubly fed induction generators, or DFIG technology, are the most vulnerable to grid faults such as voltage sags. This paper proposes a new control strategy for this type of wind generator, that allows these devices to withstand the effects of a voltage sag while following the new requirements imposed by grid operators. This new control strategy makes the use of complementary devices such as crowbars unnecessary, as it greatly reduces the value of currents originated by the fault. This ensures less costly designs for the rotor systems as well as a more economic sizing of the necessary power electronics. The strategy described here uses an electric generator model based on space-phasor theory that provides a direct control over the position of the rotor magnetic flux. Controlling the rotor magnetic flux has a direct influence on the rest of the electrical variables enabling the machine to evolve to a desired work point during the transient imposed by the grid disturbance. Simulation studies have been carried out, as well as test bench trials, in order to prove the viability and functionality of the proposed control strategy.

  4. Design and analysis of a flux intensifying permanent magnet embedded salient pole wind generator

    Science.gov (United States)

    Guo, Yujing; Jin, Ping; Lin, Heyun; Yang, Hui; Lyu, Shukang

    2018-05-01

    This paper presents an improved flux intensifying permanent magnet embedded salient pole wind generator (FI-PMESPWG) with mirror symmetrical magnetizing directions permanent magnet (PM) for improving generator's performances. The air-gap flux densities, the output voltage, the cogging torque and the d- and q-axis inductances of FI-PMESPWG are all calculated and analyzed by using the finite element method (FEM). To highlight the advantages of the proposed FI-PMESPWG, an original permanent magnet embedded salient pole wind generator (PMESPWG) model is adopted for comparison under the same operating conditions. The calculating results show that the air-gap flux densities of FI-PMESPWG are intensified with the same magnet amounts because the PMs are set in a form of V shape in each pole. The difference between d-axis inductance and q-axis inductance of the proposed FI-PMESPWG is reduced. Thus, the output power of the proposed FI-PMESPWG reaches a higher value than that of the original PMESPWG at the same current phase angle. The cogging torque is diminished because the flux path is changed. All the analysis results indicate that the electromagnetic characteristics of the proposed FI-PMESPWG are significantly better than that of the original PMESPWG.

  5. Greener corona discharge for enhanced wind generation with a simple dip-coated carbon nanotube decoration

    Science.gov (United States)

    Wu, Yishan; Li, Jun; Ye, Jianchun; Chen, Xiaohong; Li, Huili; Huang, Sumei; Zhao, Ran; Ou-Yang, Wei

    2017-10-01

    Corona discharge-induced wind (CDIW) has been widely utilized in production lines in the food and semiconductor industries and in indoor devices such as electrostatic precipitators. Some ozone is inevitably emitted, posing serious health risks to respiratory system and lung function of a human being. In this work, a greener corona discharge with enhanced wind generation for a needle-to-cylinder discharge structure is demonstrated using a simple dip-coating method to attach carbon nanotubes (CNTs) to the discharge electrode of a stainless steel needle. Compared with a conventional discharge electrode without CNT decoration, the velocity of the CDIW is greatly enhanced, the onset voltage is lowered, the energy conversion efficiency is greatly improved and the concentration of generated ozone is much reduced, making this easy method of CNT decoration a promising candidate for greener corona discharge systems. In addition, several impact factors for improved performance are discussed mathematically and phenomenologically, providing an insight into the corona discharge and wind generation.

  6. Crustal and uppermost mantle S-wave velocity below the East European Craton in northern Poland from the inversion of ambient-noise records

    Science.gov (United States)

    Lepore, Simone; Polkowski, Marcin; Grad, Marek

    2018-02-01

    The P-wave velocities (V p) within the East European Craton in Poland are well known through several seismic experiments which permitted to build a high-resolution 3D model down to 60 km depth. However, these seismic data do not provide sufficient information about the S-wave velocities (V s). For this reason, this paper presents the values of lithospheric V s and P-wave-to-S-wave velocity ratios (V p/V s) calculated from the ambient noise recorded during 2014 at "13 BB star" seismic array (13 stations, 78 midpoints) located in northern Poland. The 3D V p model in the area of the array consists of six sedimentary layers having total thickness within 3-7 km and V p in the range 1.85.3 km/s, a three-layer crystalline crust of total thickness 40 km and V p within 6.15-7.15 km/s, and the uppermost mantle, where V p is about 8.25 km/s. The V s and V p/V s values are calculated by the inversion of the surface-wave dispersion curves extracted from the noise cross correlation between all the station pairs. Due to the strong velocity differences among the layers, several modes are recognized in the 0.021 Hz frequency band: therefore, multimodal Monte Carlo inversions are applied. The calculated V s and V p/V s values in the sedimentary cover range within 0.992.66 km/s and 1.751.97 as expected. In the upper crust, the V s value (3.48 ± 0.10 km/s) is very low compared to the starting value of 3.75 ± 0.10 km/s. Consequently, the V p/V s value is very large (1.81 ± 0.03). To explain that the calculated values are compared with the ones for other old cratonic areas.

  7. San Andreas Fault dip, Peninsular Ranges mafic lower crust and partial melt in the Salton Trough, Southern California, from ambient-noise tomography

    Science.gov (United States)

    Barak, Shahar; Klemperer, Simon L.; Lawrence, Jesse F.

    2015-11-01

    We use ambient-noise tomography to improve CVM-H11.9, a community velocity model of southern California. Our new 3-D shear-velocity model with 0.05° x 0.05° lateral and 1 km vertical blocks reveals new structure beneath the San Andreas Fault (SAF), Peninsular Ranges batholith (PRB), southern Sierra Nevada batholith (SNB), and the Salton Trough (ST). We use 4 years of data recorded on 849 broadband stations, vastly more than previous studies and including our own broadband Salton Seismic Imaging Project, a 40 station transect across the ST, as well as other campaign stations in both Mexico and the United States. Mean lower crust and upper mantle wave speeds (3.6 km/s at 20 km, 4.2 km/s at 40 km) are low by global standards. Across the SAF, southeast of San Gorgonio Pass, we observe vertical to steeply dipping lateral velocity contrasts that extend beneath the Moho. Beneath the western PRB and westernmost southern SNB, we observe relatively high shear velocities (≥3.8 km/s) in the lower crust that we interpret as the mafic roots of the overlying arc. Relatively high-velocity upper mantle (up to ˜4.5 km/s) may be part of the intact arc, or possibly a remnant of the Farallon plate. Beneath the ST, we observe zones of low shear-velocity in the lower crust and upper mantle which permit up to ˜4.5% melt in the lower crust and up to ˜6% melt in the upper mantle, depending on the assumed composition and pore geometry. Our results preclude the existence of older continental crust beneath the ST and support the creation of new crust beneath the ST.

  8. Techno-economic evaluation of hybrid energy storage technologies for a solar–wind generation system

    International Nuclear Information System (INIS)

    Ren, L.; Tang, Y.; Shi, J.; Dou, J.; Zhou, S.; Jin, T.

    2013-01-01

    Highlights: ► The techno-economic feasibility of four ESSs is studied. ► The hybrid ESS applied on a renewable energy generation system is feasible. ► From the technical and economic viewpoint, case 3 is the optimal hybrid ESS. -- Abstract: Huazhong University of Science and Technology is planning to establish a hybrid solar–wind generation dynamic simulation laboratory. Energy storage technologies will be vital to this system for load leveling, power quality control and stable output. In this paper, the technical feasibility of energy storage technologies for renewable intermittent sources like wind and solar generation is analyzed. Furthermore, the different combination modes of energy storage technologies are proposed. The involved energy storage technologies include superconducting magnetic energy storage systems (SMESs), flywheels (FWs), electrochemical super-capacitors (SCs) and redox flow batteries (RFBs). Based on that, the economic analysis of hybrid energy storage technologies is conducted

  9. Comparative study of a small size wind generation system efficiency for battery charging

    Directory of Open Access Journals (Sweden)

    Mayouf Messaoud

    2013-01-01

    Full Text Available This paper presents an energetic comparison between two control strategies of a small size wind generation system for battery charging. The output voltage of the direct drive PMSG is connected to the battery through a switch mode rectifier. A DC-DC boost converter is used to regulate the battery bank current in order to achieve maximum power from the wind. A maximum powertracking algorithm calculates the current command that corresponds to maximum power output of the turbine. The DC-DC converter uses this current to calculate the duty cycle witch is necessary to control the pulse width modulated (PWM active switching device (IGPT. The system overview and modeling are presented including characteristics of wind turbine, generator, batteries, power converter, control system, and supervisory system. A simulation of the system is performed using MATLAB/SIMULINK.

  10. Power Maximization Control of Variable Speed Wind Generation System Using Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Morimoto, Shigeo; Nakamura, Tomohiko; Takeda, Yoji

    This paper proposes the sensorless output power maximization control of the wind generation system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. The generator torque is suitably controlled according to the generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control method, where the information of wind velocity is not required. Moreover, the maximum available generated power is obtained by the optimum current vector control. The current vector of PMSG is optimally controlled according to the generator speed and the required torque in order to minimize the losses of PMSG considering the voltage and current constraints. The proposed wind power generation system can be achieved without mechanical sensors such as a wind velocity detector and a position sensor. Several experimental results show the effectiveness of the proposed control method.

  11. Empirical Analysis of the Variability of Wind Generation in India: Implications for Grid Integration

    Energy Technology Data Exchange (ETDEWEB)

    Phadke, Amol; Abhyankar, NIkit; Rao, Poorvi

    2014-06-17

    We analyze variability in load and wind generation in India to assess its implications for grid integration of large scale wind projects using actual wind generation and load data from two states in India, Karnataka and Tamil Nadu. We compare the largest variations in load and net load (load ?wind, i.e., load after integrating wind) that the generation fleet has to meet. In Tamil Nadu, where wind capacity is about 53percent of the peak demand, we find that the additional variation added due to wind over the current variation in load is modest; if wind penetration reaches 15percent and 30percent by energy, the additional hourly variation is less than 0.5percent and 4.5percent of the peak demand respectively for 99percent of the time. For wind penetration of 15percent by energy, Tamil Nadu system is found to be capable of meeting the additional ramping requirement for 98.8percent of the time. Potential higher uncertainty in net load compared to load is found to have limited impact on ramping capability requirements of the system if coal plants can me ramped down to 50percent of their capacity. Load and wind aggregation in Tamil Nadu and Karnataka is found to lower the variation by at least 20percent indicating the benefits geographic diversification. These findings suggest modest additional flexible capacity requirements and costs for absorbing variation in wind power and indicate that the potential capacity support (if wind does not generate enough during peak periods) may be the issue that has more bearing on the economics of integrating wind

  12. The seismic ambient noise spectral ratio H/V under de diffuse field approach for simple layered models: Asymptotic behavior for low and high frequencies

    Science.gov (United States)

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

    2013-05-01

    The possibility of retrieving the elastodynamic Green's tensor between two points within an elastic medium from time-domain correlation of ambient noise recorded at such sites was duly confirmed in the pioneering seismic experiments by Campillo and Paul (2003) and Shapiro and Campillo (2004). Afterwards, several theoretical works on this subject have been conducted for simple models showing that such a possibility implies the condition of diffuse wavefield which requires isotropy of the illumination or the fulfillment of certain relationships between the energies of different types of waves (derived from the energy equipartition principle). In this work we examine the reliability of the usual assumptions that emerge from the Diffuse Field Approach (DFA). In particular we deal with the wavefield composition in applications regarding the passive seismic prospecting. We revise briefly the more general formulation of the DFA for full wavefield (FW). In this case the contribution of each wave to the horizontal-and vertical power spectra at surface are analyzed for a simple elastic waveguide (for instance the continental crust-upper mantle interface). Special attention is paid to their compositions at low-and high-frequencies, obtaining the relative powers of each surface wave (SW) type by means of a semi-analytical analysis. We found for some simple models that if body waves are removed from the analysis, the high-frequency horizontal asymptote of the H/V spectral ratio decreases slightly (from 1.33 for FW to around 1.14 for SW) and shows dependence on both the Poisson's ratio of the crust and the S-wave velocity contrast (while FW-H/V asymptote depends on the former only). Experimental tests for a broad band network deployed at SW Pyrenees edge provide H/V curves compatible with any of these values in the band 0.2-1Hz, approximately, supporting the applicability of the DFA approximation. Coexistence of multiple SW-modes produces distortion in the amplitude of both

  13. Spatio-temporal changes in seismic velocity associated with the 2000 activity of Miyakejima volcano as inferred from cross-correlation analyses of ambient noise

    Science.gov (United States)

    Anggono, Titi; Nishimura, Takeshi; Sato, Haruo; Ueda, Hideki; Ukawa, Motoo

    2012-12-01

    Miyakejima volcano, Japan, showed strong and interesting volcanic activities in 2000 with the occurrence of dike intrusions, caldera formation and a large amount of gas emission. To understand temporal changes of the volcanic structure associated with this activity, we apply ambient noise correlation analyses to the seismic records of five seismic stations at Miyakejima volcano from July 1999 to December 2002. We calculate cross-correlation functions (CCFs) for eight available station pairs at frequency bands of 0.4-0.8 Hz and 0.8-1.6 Hz, and retrieve the Rayleigh waves propagating with a group velocity of about 1.0 km/s. Comparing CCFs obtained for each day with the reference CCFs that are calculated from a few months of data, we estimate seismic velocity changes before and after the 2000 activity. Results at the two frequency bands show seismic velocity increase and decrease. Shallow structure at the volcanic edifice on the flanks experienced a seismic velocity increase up to 3.3%. On the other hand, the regions located close to the collapsed caldera show a seismic velocity decrease down to 2.3%. To understand the mechanisms that may introduce these seismic velocity increase and decrease, we examine several possible mechanisms of the velocity changes: stress changes due to volcanic pressure sources and caldera formation, and topographic changes. By using the deflation sources previously determined from GPS data, we calculate the stresses at depths of 0 km and 1 km at the volcano. The results suggest that the seismic velocity increases observed at seismic paths on the volcanic flank are explained by the compression caused by the deflation sources associated with magma activity in 2000. Stress sensitivities of the seismic velocity changes are estimated to be 1.5 × 10- 2 to 2.2 × 10- 2 MPa- 1 and 4.6 × 10- 3 to 2.4 × 10- 2 MPa- 1 at frequency bands of 0.4-0.8 Hz and 0.8-1.6 Hz, respectively, which are in the range of the previously reported results. Our three

  14. 3-D structure of the crust and uppermost mantle at the junction between the Southeastern Alps and External Dinarides from ambient noise tomography

    Science.gov (United States)

    Guidarelli, Mariangela; Aoudia, Abdelkrim; Costa, Giovanni

    2017-12-01

    We use ambient noise tomography to investigate the crust and the uppermost mantle structure beneath the junction between the Southern Alps, the Dinarides and the Po Plain. We obtained Rayleigh wave empirical Green's functions from cross-correlation of vertical component seismic recordings for three years (2010-2012) using stations from networks in Italy, Slovenia, Austria, Croatia, Serbia and Switzerland. We measure group and phase velocity dispersion curves from the reconstructed Rayleigh waves in the period range 5-30 and 8-37 s, respectively, and we invert the surface wave velocities for tomographic images on a grid of 0.1° × 0.1°. After the tomography, the group velocities are then inverted to compute the 3-D shear wave velocity model of the crust and the upper mantle beneath the region. Our shear wave velocity model provides the 3-D image of the structure in the region between Northeastern Italy, Slovenia and Austria. The velocity variations at shallow depths correlate with known geological and tectonic domains. We find low velocities below the Po Plain, the northern tip of the Adriatic and the Pannonian Basin, whereas higher velocities characterize the Alpine chain. The vertical cross-sections reveal a clear northward increase of the crustal thickness with a sharp northward dipping of the Moho that coincides at the surface with the leading edge of the Alpine thrust front adjacent to the Friuli Plain in Northeastern Italy. This geometry of the Moho mimics fairly well the shallow north dipping geometry of the decollement inferred from permanent GPS velocity field where high interseismic coupling is reported. From the northern Adriatic domain up to the Idrija right lateral strike-slip fault system beneath Western Slovenia, the crustal thickness is more uniform. Right across Idrija fault, to the northeast, and along its strike, we report a clear change of the physical properties of the crust up to the uppermost mantle as reflected by the lateral distribution

  15. Spatio-temporal changes of seismic velocity at Miyakejima volcano associated with the 2000 eruption based on the cross-correlation analyses of ambient seismic noise records

    Science.gov (United States)

    Anggono, T.; Nishimura, T.; Sato, H.; Ueda, H.; Ukawa, M.

    2009-12-01

    Miyakejima Island is located about 170 km to the south of Tokyo, Japan. The 2000 activity started with a small submarine eruption in late June 2000, which accompanied earthquake swarms. A caldera was formed from July to August and had a diameter of about 1.6 km. Since then the volcanic gas was effused and the activity continued for more than four years. We analyze the ambient seismic noise recorded from July 1999 to December 2002 at four NIED seismic stations to study the volcano structure behavior associated with this volcanic activity. The continuous records are sampled at frequency of 100 Hz with an A/D resolution of 16-bit. We apply cross-correlation analyses to the continuous records of vertical component of short period seismometers (1 s) for every possible pair of stations. Before calculating the cross-correlation function (CCF), we bandpass filter the data using three-order Butterworth filter with frequency bands 0.4 - 0.8 Hz and 0.8 - 1.6 Hz. We calculate the CCFs with 60 s window length, and then stack for one day data. The observed CCFs are symmetric at both negative and positive lag times; this means that the distribution of noise sources is quite homogeneous surrounding the Miyakejima Island. We define a reference Green’s function (RGF) for every station pair by stacking the CCFs for about 10 months in 2002 during which no major instrumental errors were found. Once RGF is defined for each station pair, we calculate the cross-correlation coefficient between the RGF and the CCFs of each day, and select “good” CCFs that have cross-correlation coefficient larger than 0.7 and lag time smaller than +/- 0.5 s. We pick travel times of the maximum amplitude of the wave packets at positive and negative lag times, which correspond to the travel time of Rayleigh waves between two stations, from the RGF and the “good” CCFs of each day. To estimate the changes in the medium, we calculate the average travel time difference for periods July 1999 - May 2000

  16. Can we trace the eastern Gondwanan margin in Australia? New perspectives from transdimensional inversion of ambient noise for 3D shear velocity structure

    Science.gov (United States)

    Pilia, S.; Rawlinson, N.; Direen, N. G.

    2013-12-01

    Although the notion of Rodinia is quite well accepted in the geoscience community, the location and nature of the eastern continental margin of the Gondwana fragment in Australia is still vague and remains one of the most hotly debated topics in Australian geology. Moreover, most post-Rodinian reconstructions models choose not to tackle the ';Tasmanian challenge', and focus only on the tectonic evolution of mainland southeast Australia, thereby conveniently ignoring the wider tectonic implications of Tasmania's complex geological history. One of the chief limitations of the tectonic reconstructions in this region is a lack of information on Paleozoic (possibly Proterozoic) basement structures. Vast Mesozoic-Cainozoic sedimentary and volcanic cover sequences obscure older outcrops and limit the power of direct observational techniques. In response to these challenges, our effort is focused on ambient seismic noise for imaging 3D crustal shear velocity structure using surface waves, which is capable of illuminating basement structure beneath younger cover. The data used in this study is sourced from the WOMBAT transportable seismic array, which is compounded by around 650 stations spanning the majority of southeastern Australia, including Tasmania and several islands in Bass Strait. To produce the highest quality Green's functions, careful processing of the data has been performed, after which group velocity dispersion measurements have been carried out using a frequency-time analysis method on the symmetric component of the empirical Green's functions (EGFs). Group dispersion measurements from the EGFs have been inverted using a novel hierarchical, transdimensional, Bayesian algorithm to obtain Rayleigh-wave group velocity maps at different periods from 2 to 30 s. The new approach has several advantages in that the number and distribution of model parameters are implicitly controlled by the data, in which the noise is treated as unknown in the inversion. This

  17. Incipient Stator Insulation Fault Detection of Permanent Magnet Synchronous Wind Generators Based on Hilbert–Huang Transformation

    DEFF Research Database (Denmark)

    Wang, Chao; Liu, Xiao; Chen, Zhe

    2014-01-01

    Incipient stator winding fault in permanent magnet synchronous wind generators (PMSWGs) is very difficult to be detected as the fault generated variations in terminal electrical parameters are very weak and chaotic. This paper simulates the incipient stator winding faults at different degree...

  18. A Control Approach and Supplementary Controllers for a Stand-Alone System with Predominance of Wind Generation

    Directory of Open Access Journals (Sweden)

    Tiago Lukasievicz

    2018-02-01

    Full Text Available This paper proposes a control approach and supplementary controllers for the operation of a hybrid stand-alone system composed of a wind generation unit and a conventional generation unit based on synchronous generator (CGU. The proposed controllers allow the islanded or isolated operation of small power systems with predominance of wind generation. As an advantage and a paradigm shift, the DC-link voltage of the wind unit is controlled by means of a conventional synchronous generator connected to the AC grid of the system. Two supplementary controllers, added to a diesel generator (DIG and to a DC dump load (DL, are proposed to control the DC-link voltage. The wind generation unit operates in V-f control mode and the DIG operates in PQ control mode, which allows the stand-alone system to operate either in wind-diesel (WD mode or in wind-only (WO mode. The strong influence of the wind turbine speed variations in the DC-link voltage is mitigated by a low-pass filter added to the speed control loop of the wind turbine. The proposed control approach does not require the use battery bank and ultra-capacitor to control the DC-link voltage in wind generation units based on fully rated converter.

  19. Effects of voltage unbalance and system harmonics on the performance of doubly fed induction wind generators

    Science.gov (United States)

    Kiani, Morgan Mozhgan

    Inherent difficulties in management of electric power in the presence of an increasing demand for more energy, non-conventional loads such as digital appliances, and non-sustainable imported fossil fuels has initiated a multi-folded effort by many countries to restructure the way electric energy is generated, dispatched, and consumed. Smart power grid is the manifestation of many technologies that would eventually transforms the existing power grid into a more flexible, fault resilient, and intelligent system. Integration of distributed renewable energy sources plays a central role in successful implementation of this transformation. Among the renewable options, wind energy harvesting offers superior engineering and economical incentives with minimal environmental impacts. Doubly fed induction generators (DFIG) have turned into a serious contender for wind energy generators due to their flexibility in control of active and reactive power with minimal silicon loss. Significant presence of voltage unbalance and system harmonics in finite inertia transmission lines can potentially undermine the reliability of these wind generators. The present dissertation has investigated the impacts of system unbalances and harmonics on the performance of the DFIG. Our investigation indicates that these effects can result in an undesirable undulation in the rotor shaft which can potentially invoke mechanical resonance, thereby causing catastrophic damages to the installations and the power grid. In order to remedy the above issue, a control solution for real time monitoring of the system unbalance and optimal excitation of the three phase rotor currents in a DFIG is offered. The optimal rotor currents will create appropriate components of the magneto-motive force in the airgap that will actively compensate the undesirable magnetic field originated by the stator windings. Due to the iterative nature of the optimization procedure, field reconstruction method has been incorporated

  20. Model of analysis of maximum loads in wind generators produced by extreme winds

    International Nuclear Information System (INIS)

    Herrera – Sánchez, Omar; Schellong, Wolfgang; González – Fernández, Vladimir

    2010-01-01

    The use of the wind energy by means of the wind turbines in areas of high risk of occurrence of Hurricanes comes being an important challenge for the designers of wind farm at world for some years. The wind generator is not usually designed to support this type of phenomena, for this reason the areas of high incidence of tropical hurricanes of the planning are excluded, that which, in occasions disables the use of this renewable source of energy totally, either because the country is very small, or because it coincides the area of more potential fully with that of high risk. To counteract this situation, a model of analysis of maxims loads has been elaborated taken place the extreme winds in wind turbines of great behavior. This model has the advantage of determining, in a chosen place, for the installation of a wind farm, the micro-areas with higher risk of wind loads above the acceptable for the standard classes of wind turbines. (author)

  1. Smart pitch control strategy for wind generation system using doubly fed induction generator

    Science.gov (United States)

    Raza, Syed Ahmed

    A smart pitch control strategy for a variable speed doubly fed wind generation system is presented in this thesis. A complete dynamic model of DFIG system is developed. The model consists of the generator, wind turbine, aerodynamic and the converter system. The strategy proposed includes the use of adaptive neural network to generate optimized controller gains for pitch control. This involves the generation of controller parameters of pitch controller making use of differential evolution intelligent technique. Training of the back propagation neural network has been carried out for the development of an adaptive neural network. This tunes the weights of the network according to the system states in a variable wind speed environment. Four cases have been taken to test the pitch controller which includes step and sinusoidal changes in wind speeds. The step change is composed of both step up and step down changes in wind speeds. The last case makes use of scaled wind data collected from the wind turbine installed at King Fahd University beach front. Simulation studies show that the differential evolution based adaptive neural network is capable of generating the appropriate control to deliver the maximum possible aerodynamic power available from wind to the generator in an efficient manner by minimizing the transients.

  2. Analysis And Synthesis Of Model Reference Controller For Variable Speed Wind Generators Inertial Support

    Science.gov (United States)

    Bećirović, Elvisa; Osmić, Jakub; Kušljugić, Mirza; Perić, Nedjeljko

    2015-01-01

    Model Reference Controller (MRC) for contribution of Variable Speed Wind Generators (VSWG) in inertial response of Electrical Power System (EPS) is presented and analyzed in this paper. MRC is synthesized based on a model of Generating Unit With non-Reheat Steam Turbine (GUNRST) thus enabling VSWG to emulate GUNRST response during the initial stage of dynamic frequency response ie inertial phase. Very important property of conventional steam generating units is that its contribution to inertial phase response is independent from the initial generating power. By using MRC in VSWG it is accomplished that in most common wind speed region (3-12 m/s) VSWG inertial support is almost independent from wind speed. Since in most EPSs VSWG replaces conventional steam generators, application of MRC algorithm provides that the characteristics of EPS in terms of inertial response are preserved, regardless of the growing trend of introducing VSWG. Evaluation analysis of the proposed MRC is performed on modified nine bus power system when VSWG with MRC is connected to one of the power system buses.

  3. Ambient diagnostics

    CERN Document Server

    Cai, Yang

    2014-01-01

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

  4. Options to Improve the Quality of Wind Generation Output Forecasting with the Use of Available Information as Explanatory Variables

    Directory of Open Access Journals (Sweden)

    Rafał Magulski

    2015-06-01

    Full Text Available Development of wind generation, besides its positive aspects related to the use of renewable energy, is a challenge from the point of view of power systems’ operational security and economy. The uncertain and variable nature of wind generation sources entails the need for the for the TSO to provide adequate reserves of power, necessary to maintain the grid’s stable operation, and the actors involved in the trading of energy from these sources incur additional of balancing unplanned output deviations. The paper presents the results of analyses concerning the options to forecast a selected wind farm’s output exercised by means of different methods of prediction, using a different range of measurement and forecasting data available on the farm and its surroundings. The analyses focused on the evaluation of forecast errors, and selection of input data for forecasting models and assessment of their impact on prediction quality improvement.

  5. A doubly-fed induction generator-based wind generation system with quasi-sine rotor injection

    Science.gov (United States)

    Yuvarajan, S.; Fan, Lingling

    Wind generating systems use doubly-fed induction generators (DFIGs) to achieve high conversion efficiency and to reduce the installation cost. The paper proposes and analyzes a simple DFIG-based wind generation system in which the excitation power is obtained from a photovoltaic (PV) panel and battery. The proposed scheme is suitable for small wind power systems for which a complex field orientation control is not justified. It can be used for stand-alone operation and also grid-tied operation. The rotor of the DFIG is applied with a quasi-sine wave instead of a sine wave. The operation and harmonic characteristics of the scheme are established using analysis, simulation, and experimentation. The details of the control circuit are given along with the experimental waveforms of voltages and currents and frequency spectra. The total harmonic distortion in the output current is found to be around 8%.

  6. Effect of wind generation system types on Micro-Grid (MG) fault performance during both standalone and grid connected modes

    International Nuclear Information System (INIS)

    Kamel, Rashad M.

    2014-01-01

    Highlights: • This paper evaluated the effects of different wind system types on fault performance of Micro-Grid. • Both standalone and grid connected modes are considered. • The MG earthing system configuration is taken in consideration. - Abstract: Recently, there are three wind generation (WG) system types. The first type is called Fixed Speed Wind Generation (FSWG) system, which employs squirrel cage induction generators. Double Fed Induction Generator (DFIG) is utilized in the second type. The third type is called Full Converter Wind Generation (FCWG) system, which is interfaced with Micro-Grid (MG) through a back to back converter. During fault occurrence, each WG has its performance and characteristics which are determined by the generator physical characteristics and the MG earthing system configuration. For some WG types, the fault current depends also on the control algorithm of the power converter. The main target of this paper is to investigate and estimate how the fault performance of MG during both standalone and grid-connected modes is influenced by the type of WG. It is found during standalone mode that the type of the employed WG has a dominant impact on the MG performance under fault disturbance. On the contrary, the type of the employed WG has a negligible effect on the MG fault performance during grid-connected mode. This is because the main grid contributes most of the fault current. Effects of earthing system type on MG performance are highlighted

  7. Design and construction of the small wind generator called “AR-SF-500” for the ore milling to a laborator y scale

    OpenAIRE

    Romero Baylón, Alfonso; UNMSM; Flores Chávez, Silvana; UNMSM; Pacheco, Werner; UNMSM

    2014-01-01

    The small wind generator called “AR-SFWP- 500” has a dynamo that generated a potency of 500 watts, which characterize for having in its internal structure, the called “permanent magnet” for working with small wind generators, such as employing in rural zones, where there is a lack of electric energy. In this sense, the purpose of the paper, treats explaining the process of design and construction of the Small Wind Generator AR-SFWP- 500, whose principle of functioning is based in transform th...

  8. Classroom Noise and Teachers' Voice Production

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2017-12-01

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

  10. 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...

  11. The impact of increased interconnection on electricity systems with large penetrations of wind generation: A case study of Ireland and Great Britain

    DEFF Research Database (Denmark)

    Denny, E.; Tuohy, A.; Meibom, Peter

    2010-01-01

    interconnection for the island of Ireland with large penetrations of wind generation. The results suggest that increased interconnection should reduce average prices in Ireland, and the variability of those prices. The simulations also suggest that while increased interconnection may reduce carbon dioxide...... emissions in Ireland, Great Britain would experience an increase in emissions, resulting in total emissions remaining almost unchanged. The studies suggest that increased interconnection would not reduce excess wind generation. This is because under unit commitment techniques which incorporate wind power...

  12. An overview of wind energy, taking into consideration several imporatn issues, including an analisys of regulatory requirements for the connection of wind generation into the power system

    OpenAIRE

    Gimenez Alvarez, Juan Manuel; SCHWEICKARDT, GUSTAVO; GÓMEZ TARGARONA, JUAN CARLOS

    2012-01-01

    Pollution problems such as greenhouse effect as well as the high value and volatility of fuel prices have forced and accelerated the development and use of renewable energy sources. In this work a complete revision of wind generation is presented. In the first part a brief history of the wind energy developments is detailed. Next, some commentaries related to the present and future state are made. Then, a revision of the modern structures of wind generation is realized. In fourth place it is ...

  13. Long-term exposure to ambient air pollution and traffic noise and incident hypertension in seven cohorts of the European study of cohorts for air pollution effects (ESCAPE).

    Science.gov (United States)

    Fuks, Kateryna B; Weinmayr, Gudrun; Basagaña, Xavier; Gruzieva, Olena; Hampel, Regina; Oftedal, Bente; Sørensen, Mette; Wolf, Kathrin; Aamodt, Geir; Aasvang, Gunn Marit; Aguilera, Inmaculada; Becker, Thomas; Beelen, Rob; Brunekreef, Bert; Caracciolo, Barbara; Cyrys, Josef; Elosua, Roberto; Eriksen, Kirsten Thorup; Foraster, Maria; Fratiglioni, Laura; Hilding, Agneta; Houthuijs, Danny; Korek, Michal; Künzli, Nino; Marrugat, Jaume; Nieuwenhuijsen, Mark; Östenson, Claes-Göran; Penell, Johanna; Pershagen, Göran; Raaschou-Nielsen, Ole; Swart, Wim J R; Peters, Annette; Hoffmann, Barbara

    2017-04-01

    We investigated whether traffic-related air pollution and noise are associated with incident hypertension in European cohorts. We included seven cohorts of the European study of cohorts for air pollution effects (ESCAPE). We modelled concentrations of particulate matter with aerodynamic diameter ≤2.5 µm (PM2.5), ≤10 µm (PM10), >2.5, and ≤10 µm (PMcoarse), soot (PM2.5 absorbance), and nitrogen oxides at the addresses of participants with land use regression. Residential exposure to traffic noise was modelled at the facade according to the EU Directive 2002/49/EC. We assessed hypertension as (i) self-reported and (ii) measured (systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg or intake of BP lowering medication (BPLM). We used Poisson regression with robust variance estimation to analyse associations of traffic-related exposures with incidence of hypertension, controlling for relevant confounders, and combined the results from individual studies with random-effects meta-analysis. Among 41 072 participants free of self-reported hypertension at baseline, 6207 (15.1%) incident cases occurred within 5-9 years of follow-up. Incidence of self-reported hypertension was positively associated with PM2.5 (relative risk (RR) 1.22 [95%-confidence interval (CI):1.08; 1.37] per 5 µg/m³) and PM2.5 absorbance (RR 1.13 [95% CI:1.02; 1.24] per 10 - 5m - 1). These estimates decreased slightly upon adjustment for road traffic noise. Road traffic noise was weakly positively associated with the incidence of self-reported hypertension. Among 10 896 participants at risk, 3549 new cases of measured hypertension occurred. We found no clear associations with measured hypertension. Long-term residential exposures to air pollution and noise are associated with increased incidence of self-reported hypertension. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For Permissions, please email: journals.permissions@oup.com.

  14. Noise suppression by noise

    OpenAIRE

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

    2001-01-01

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

  15. Applications of wind generation for power system frequency control, inter-area oscillations damping and parameter identification

    Science.gov (United States)

    Wilches-Bernal, Felipe

    Power systems around the world are experiencing a continued increase in wind generation as part of their energy mix. Because of its power electronics interface, wind energy conversion systems interact differently with the grid than conventional generation. These facts are changing the traditional dynamics that regulate power system behavior and call for a re-examination of traditional problems encountered in power systems like frequency response, inter-area oscillations and parameter identification. To address this need, realistic models for wind generation are necessary. The dissertation implements such models in a MATLAB-based flexible environment suited for power system research. The dissertation continues with an analysis of the frequency response of a test power system dependent mainly on a mode referred to as the frequency regulation mode. Using this test system it is shown that its frequency regulation capability is reduced with wind penetration levels of 25% and above. A controller for wind generation to restore the frequency response of the system is then presented. The proposed controller requires the WTG to operate in a deloaded mode, a condition that is obtained through pitching the wind turbine blades. Time simulations at wind penetration levels of 25% and 50% are performed to demonstrate the effectiveness of the proposed controller. Next, the dissertation evaluates how the inter-area oscillation of a two-machine power system is affected by wind integration. The assessment is performed based on the positioning of the WTG, the level of wind penetration, and the loading condition of the system. It is determined that integrating wind reduces the damping of the inter-area mode of the system when performed in an area that imports power. For this worst-case scenario, the dissertation proposes two controllers for wind generation to improve the damping of the inter-area mode. The first controller uses frequency as feedback signal for the active power control

  16. Wind Generation Feasibility Study for Sac & Fox Tribe of the Mississippi in Iowa (Meskwaki Nation)

    Energy Technology Data Exchange (ETDEWEB)

    Lasley, Larry C. [Sac & Fox Tribe of the Mississippi in Iowa

    2013-03-19

    Wind Generation Feasibility Study prepared by Wind Utility Consulting, PC and Preliminary Environmental Documentation Report prepared by Snyder & Associates.

  17. Classroom Noise and Teachers' Voice Production.

    Science.gov (United States)

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

    2015-10-01

    The aim of this study was to research the associations between noise (ambient and activity noise) and objective metrics of teachers' voices in real working environments (i.e., classrooms). Thirty-two female and 8 male teachers from 14 elementary schools were randomly selected for the study. Ambient noise was measured during breaks in unoccupied classrooms and, likewise, the noise caused by pupils' activity during lessons. Voice samples were recorded before and after a working day. Voice variables measured were sound pressure level (voice SPL), fundamental frequency, jitter, shimmer, and the tilt of the sound spectrum slope (alpha ratio). The ambient noise correlated most often with the fundamental frequency of men and voice SPL, whereas activity noise correlated with the alpha ratio and perturbation values. Teachers working in louder ambient noise spoke more loudly before work than those working in lower noise levels. Voice variables generally changed less during work among teachers working in loud activity noise than among those working in lower noise levels. Ambient and activity noises affect teachers' voice use. Under loud ambient noise teachers seem to speak habitually loudly, and under loud activity noise teachers' ability to react to loading deteriorates.

  18. Can we use the q-Gaussian of ambient noise fluctuations as a vulnerability index? A case study in Cultural Heritage buildings

    Science.gov (United States)

    Vallianatos, Filippos; Koutalonis, Ioannis; Moisidi, Margarita; Chatzopoulos, Georgios

    2018-05-01

    In this work we study in terms of Tsallis statistical mechanics the properties of microtremors' fluctuations in two church bell towers, which are monuments of cultural heritage, in the city of Chania (Crete, Greece). We have shown that fluctuations of ambient vibrations recordings in the Church tower bells follow a q-Gaussian distribution. The behavior of Tsallis q parameter with the level (high) of the measuring point within the tower and the amplification factors at that points as extracted from horizontal-to-vertical (HVSR) spectral ratios are presented and discussed. Since q decreases as the amplification factor increases, we could suggest q as a vulnerability index, where, as q decreases approaching unity, then the structural system is getting more vulnerable. The latter approach suggests that introducing ideas of Tsallis statistics could be useful in characterizing extremely complex processes as that governed the estimation of seismic vulnerability in which a multidisciplinary approach is required.

  19. Challenges, problems and possible solutions in wind generator systems from the aspect of forecast, planning and delivery of wind energy

    International Nuclear Information System (INIS)

    Giovski, Nikola

    2014-01-01

    The fundamental difficulties of integrating wind energy into the power system arise from its large temporal variability and limited predictability. That's why the integration of wind power presents major challenge for today's operating and planning practices of the power system operators. Accurate predictions of the possible wind power output, in time intervals relevant for creating schedules for production and exchange capacity, allows to system operators and dispatching personnel more efficient power system management. Despite the challenges and problems that arise due to integration of wind power into power systems, which need to be solved or reduced, wind power has its advantages that should be utilized. The effective integration of wind power plants into the transmission grid should allow them to represent the backbone of future energy systems. Modern wind generators represent production units that have the ability to participate in the management of energy systems e.g. in the regulation of frequency, voltage and other network operating requirements. This paper provides a brief overview of global experiences with the challenges, problems and possible solutions that appear in wind generator systems from the aspect of forecasting, planning and delivery of wind energy. (author)

  20. Wind-generated Electricity in China: Decreasing Potential, Inter-annual Variability and Association with Changing Climate.

    Science.gov (United States)

    Sherman, Peter; Chen, Xinyu; McElroy, Michael B

    2017-11-24

    China hosts the world's largest market for wind-generated electricity. The financial return and carbon reduction benefits from wind power are sensitive to changing wind resources. Wind data derived from an assimilated meteorological database are used here to estimate what the wind generated electricity in China would have been on an hourly basis over the period 1979 to 2015 at a geographical resolution of approximately 50 km × 50 km. The analysis indicates a secular decrease in generating potential over this interval, with the largest declines observed for western Inner Mongolia (15 ± 7%) and the northern part of Gansu (17 ± 8%), two leading wind investment areas. The decrease is associated with long-term warming in the vicinity of the Siberian High (SH), correlated also with the observed secular increase in global average surface temperatures. The long-term trend is modulated by variability relating to the Pacific Decadal Oscillation (PDO) and the Arctic Oscillation (AO). A linear regression model incorporating indices for the PDO and AO, as well as the declining trend, can account for the interannual variability of wind power, suggesting that advances in long-term forecasting could be exploited to markedly improve management of future energy systems.

  1. 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......, dehierarchization, ubiquity and the production of unfocused sensations in contrast to the conventional notion of the aesthetic experience as a focused contemplation of a stationary object....

  2. Design of DC-DC Converter and its Control for a Wind Generation System Connected to an Isolated Load

    Directory of Open Access Journals (Sweden)

    Carlos A. Ramírez Gómez

    2013-11-01

    Full Text Available A method to design a Buck converter and its control, which are associated to a wind generation system that is feeding an isolated load, is presented in this paper. To design the converter a Thevenin equivalent is deduced, which represents the behavior of the wind turbine, the permanent magnet synchronous generator, and the rectifier. The design of the converter elements guarantees input/output voltages and inductor current ripples of 5 % or less. The output voltage control is developed with a proportional-integral-derivative controller and as design criteria a damping of 0,707 and cutoff frequency of 1/5 converter commutation frequency are selected. The designed controller regulates the output voltage faced load perturbations and wind speed variations. 

  3. Near surface structure of the North Anatolian Fault Zone near 30°E from Rayleigh and Love wave tomography using ambient seismic noise.

    Science.gov (United States)

    Taylor, G.; Rost, S.; Houseman, G. A.; Hillers, G.

    2017-12-01

    By utilising short period surface waves present in the noise field, we can construct images of shallow structure in the Earth's upper crust: a depth-range that is usually poorly resolved in earthquake tomography. Here, we use data from a dense seismic array (Dense Array for Northern Anatolia - DANA) deployed across the North Anatolian Fault Zone (NAFZ) in the source 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 obtain maps of group velocity variation using surface wave tomography applied to short period (1- 6 s) Rayleigh and Love waves to construct high-resolution images of SV and SH-wave velocity in the upper 5 km of a 70 km x 35 km region centred on the eastern end of the fault segment that ruptured in the 1999 Izmit earthquake. The average Rayleigh wave group velocities in the region vary between 1.8 km/s at 1.5 s period, to 2.2 km/s at 6 s period. The NAFZ bifurcates into northern and southern strands in this region; both are active but only the northern strand ruptured in the 1999 event. The signatures of both the northern and southern branches of the NAFZ are clearly associated with strong gradients in seismic velocity that also denote the boundaries of major tectonic units. This observation implies that the fault zone exploits the pre-existing structure of the Intra-Pontide suture zone. To the north of the NAFZ, we observe low S-wave velocities ( 2.0 km/s) associated with the unconsolidated sediments of the Adapazari basin, and blocks of weathered terrigenous clastic sediments. To the south of the northern branch of the NAFZ in the Armutlu block, we detect higher velocities ( 2.9 km/s) associated with a shallow crystalline basement, in particular a block of metamorphosed schists and marbles that bound the northern branch of the NAFZ.

  4. Efficiency of small wind generator powered water pumping systems; Rendimento de unidade de bombeamento de agua acionada por gerador eolico de pequeno porte

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Mendeleyev Guerreiro; Carvalho, Paulo Cesar Marques de; Costa, Levy Ferreira [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Engenharia Eletrica; Borges Neto, Manuel Rangel [Centro Federal de Educacao Tecnologica de Petrolina (CEFET), PE (Brazil)

    2008-07-01

    The present paper aims to evaluate the efficiency of a small wind generator powered water pumping system; the generator is a permanent magnet generator of 1 kw of axial flow, using three fiber glass blades with 2.46 m diameter. The used centrifugal pump is connected to a 0.5 c v motor, three-phase, frequency of 60 Hz, rotational speed of 3450 rpm. For the efficiency evaluation a shell anemometer, a flow and pressure sensor were used, connected to a data logger to the collection and storage of the data. An energy analyzer was also used to collect the current, voltage and power generated from the wind generator. (author)

  5. Noise thermometer

    International Nuclear Information System (INIS)

    Von Brixy, H.; Kakuta, Tsunemi.

    1996-03-01

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

  6. Noise thermometer

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-03-01

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

  7. 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...

  8. 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...

  9. An Examination of AC/HVDC Power Circuits for Interconnecting Bulk Wind Generation with the Electric Grid

    Directory of Open Access Journals (Sweden)

    Daniel Ludois

    2010-06-01

    Full Text Available The application of high voltage dc (HVDC transmission for integrating large scale and/or off-shore wind generation systems with the electric grid is attractive in comparison to extra high voltage (EHV ac transmission due to a variety of reasons. While the technology of classical current sourced converters (CSC using thyristors is well established for realization of large HVDC systems, the technology of voltage sourced converters (VSC is emerging to be an alternative approach, particularly suitable for multi-terminal interconnections. More recently, a more modular scheme that may be termed ‘bridge of bridge’ converters (BoBC has been introduced to realize HVDC systems. While all these three approaches are functionally capable of realizing HVDC systems, the converter power circuit design trade-offs between these alternatives are not readily apparent. This paper presents an examination of these topologies from the point of view of power semiconductor requirements, reactive component requirements, operating losses, fault tolerance, multi-terminal operation, modularity, complexity, etc. Detailed analytical models will be used along with a benchmark application to develop a comparative evaluation of the alternatives that maybe used by wind energy/bulk transmission developers for performing engineering trade-off studies.

  10. 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)

  11. Wind Generated Ocean Waves

    DEFF Research Database (Denmark)

    Frigaard, Peter

    2001-01-01

    Book review: I. R. Young, Elsevier Ocean Engineering Series, Vol 2. Elsevier Science, Oxford, UK, 1999, 306 pages, hardbound, ISBN 0-08-043317-0, Dfl. 275,00 (US$ 139.50)......Book review: I. R. Young, Elsevier Ocean Engineering Series, Vol 2. Elsevier Science, Oxford, UK, 1999, 306 pages, hardbound, ISBN 0-08-043317-0, Dfl. 275,00 (US$ 139.50)...

  12. Periodismo ambiental

    Directory of Open Access Journals (Sweden)

    Lucía Lemos

    2015-01-01

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

  13. ANALYSIS OF MONTE CARLO SIMULATION SAMPLING TECHNIQUES ON SMALL SIGNAL STABILITY OF WIND GENERATOR- CONNECTED POWER SYSTEM

    Directory of Open Access Journals (Sweden)

    TEMITOPE RAPHAEL AYODELE

    2016-04-01

    Full Text Available Monte Carlo simulation using Simple Random Sampling (SRS technique is popularly known for its ability to handle complex uncertainty problems. However, to produce a reasonable result, it requires huge sample size. This makes it to be computationally expensive, time consuming and unfit for online power system applications. In this article, the performance of Latin Hypercube Sampling (LHS technique is explored and compared with SRS in term of accuracy, robustness and speed for small signal stability application in a wind generator-connected power system. The analysis is performed using probabilistic techniques via eigenvalue analysis on two standard networks (Single Machine Infinite Bus and IEEE 16–machine 68 bus test system. The accuracy of the two sampling techniques is determined by comparing their different sample sizes with the IDEAL (conventional. The robustness is determined based on a significant variance reduction when the experiment is repeated 100 times with different sample sizes using the two sampling techniques in turn. Some of the results show that sample sizes generated from LHS for small signal stability application produces the same result as that of the IDEAL values starting from 100 sample size. This shows that about 100 sample size of random variable generated using LHS method is good enough to produce reasonable results for practical purpose in small signal stability application. It is also revealed that LHS has the least variance when the experiment is repeated 100 times compared to SRS techniques. This signifies the robustness of LHS over that of SRS techniques. 100 sample size of LHS produces the same result as that of the conventional method consisting of 50000 sample size. The reduced sample size required by LHS gives it computational speed advantage (about six times over the conventional method.

  14. Characterization of an Outdoor Ambient Radio Frequency Environment

    Science.gov (United States)

    2016-02-16

    TYPE Final 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Test Operations Procedure (TOP) 06-2-595 Characterization of an Outdoor Ambient ...DTIC), AD No.: 14. ABSTRACT This TOP provides procedures to characterize an ambient radio frequency (RF) environment (sometimes referred to as...spectrum analyzer, ambient RF noise floor, RF interference 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18

  15. Model/data comparison of typhoon-generated noise

    International Nuclear Information System (INIS)

    Wang Jing-Yan; Li Feng-Hua

    2016-01-01

    Ocean noise recorded during a typhoon can be used to monitor the typhoon and investigate the mechanism of the wind-generated noise. An analytical expression for the typhoon-generated noise intensity is derived as a function of wind speed. A “bi-peak” structure was observed in an experiment during which typhoon-generated noise was recorded. Wind speed dependence and frequency dependence were also observed in the frequency range of 100 Hz–1000 Hz. The model/data comparison shows that results of the present model of 500 Hz and 1000 Hz are in reasonable agreement with the experimental data, and the typhoon-generated noise intensity has a dependence on frequency and a power-law dependence on wind speed. (special topic)

  16. Noise Pollution

    Science.gov (United States)

    ... Us Share Clean Air Act 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 ...

  17. Modeling and Maximum Power Point Tracking Control of Wind Generating Units Equipped with Permanent Magnet Synchronous Generators in Presence of Losses

    Directory of Open Access Journals (Sweden)

    Andrea Bonfiglio

    2017-01-01

    Full Text Available This paper focuses on the modeling of wind turbines equipped with direct drive permanent magnet synchronous generators for fundamental frequency power system simulations. Specifically, a procedure accounting for the system active power losses to initialize the simulation starting from the load flow results is proposed. Moreover, some analytical assessments are detailed on typical control schemes for fully rated wind turbine generators, thereby highlighting how active power losses play a fundamental role in the effectiveness of the wind generator control algorithm. Finally, the paper proposes analytical criteria to design the structure and the parameters of the regulators of the wind generator control scheme. Simulations performed with Digsilent Power Factory validated the proposed procedure, highlighting the impact of active power losses on the characterization of the initial steady state and that the simplifying assumptions done in order to synthesize the controllers are consistent with the complete modeling performed by the aforementioned power system simulator.

  18. Stochastic Prediction of Wind Generating Resources Using the Enhanced Ensemble Model for Jeju Island’s Wind Farms in South Korea

    OpenAIRE

    Deockho Kim; Jin Hur

    2017-01-01

    Due to the intermittency of wind power generation, it is very hard to manage its system operation and planning. In order to incorporate higher wind power penetrations into power systems that maintain secure and economic power system operation, an accurate and efficient estimation of wind power outputs is needed. In this paper, we propose the stochastic prediction of wind generating resources using an enhanced ensemble model for Jeju Island’s wind farms in South Korea. When selecting the poten...

  19. Co-generation of hydrogen from nuclear and wind: the effect on costs of realistic variations in wind generation. Paper no. IGEC-1-094

    International Nuclear Information System (INIS)

    Miller, A.I.; Duffey, R.B.

    2005-01-01

    Can electricity from high-capacity nuclear reactors be blended with the variable output of wind turbines to produce electrolytic hydrogen competitively? To be competitive with alternative sources, hydrogen produced by conventional electrolysis requires low-cost electricity (likely <2.5 cents US/kW.h). One approach is to operate interruptibly, allowing an installation to sell electricity when the grid price is high and to make hydrogen when it is low. Our previous studies show that this could be cost-competitive using nuclear power generator producing electricity around 3 cents US/kW.h. Although similar unit costs are projected for wind-generated electricity, idleness of the electrolysis facility due to the variability of wind-generated electricity imposes a significant cost penalty. This paper reports on ongoing work on the economics of blending electricity from nuclear and wind sources by using wind-generated power, when available, to augment the current through electrolysis equipment that is primarily nuclear-powered - a concept we call NuWind. A voltage penalty accompanies the higher current. A 10% increase in capital cost for electrolysis equipment to enable it to accommodate the higher rate of hydrogen generation is still substantially cheaper than the capital cost of wind-dedicated electrolysis. Real-time data for electricity costs have been combined with real-time wind variability. The variability in wind fields between sites was accommodated by assigning average wind speeds that produced an average electricity generation from wind of between 32 and 42% of peak capacity, which is typical of the expectations for superior wind-generation sites. (author)

  20. Maintaining stability of standalone Micro-Grid by employing electrical and mechanical fault ride through techniques upon fixed speed wind generation systems

    International Nuclear Information System (INIS)

    Kamel, Rashad M.

    2013-01-01

    Highlights: • This paper presented two fault ride through techniques for fixed speed wind systems. • The first technique is implemented by inserting a series resistance with the terminals of wind generator. • Second technique is performed by adapting the gear ratio to spill some mechanical power. - Abstract: This study presents two different Fault Ride Through (FRT) techniques to keep and restore stability of Fixed Speed Wind Generation system (FSWGs) installed in standalone Micro-Grid (MG). The first technique is an electrical FRT and is implemented by inserting a series resistance with the terminals of FSWGs during fault to maintain reasonable value of terminal voltage and consequently help stability restoration. The second controller is a mechanical FRT controller and is performed by change the gear ratio of wind generation systems to spill part of extracted mechanical power and consequently improving stability issue. Obtained results proved that each controller able to maintain the stability of FSWGs under the most severe disturbance conditions (400 ms three phase fault at FSWGs terminals). The first controller is faster than the second controller in restoring FSWGs stability. Superior results and performances are obtained when the two FRT techniques are employed simultaneously. Without employing any one of the two FRT techniques, FSWGs is not able to maintain or restore its stability after fault clearing. Consequently, MG will lose one of its micro-sources and cannot keep its stability during the standalone mode, unless load shedding strategy is activated. The two proposed controllers are simple, effective, and economical attractive

  1. The impact of increased interconnection on electricity systems with large penetrations of wind generation. A case study of Ireland and Great Britain

    International Nuclear Information System (INIS)

    Denny, E.; Tuohy, A.; Keane, A.; Flynn, D.; O'Malley, M.; Meibom, P.; Mullane, A.

    2010-01-01

    Increased interconnection has been highlighted as potentially facilitating the integration of wind generation in power systems by increasing the flexibility to balance the variable wind output. This paper utilizes a stochastic unit commitment model to simulate the impacts of increased interconnection for the island of Ireland with large penetrations of wind generation. The results suggest that increased interconnection should reduce average prices in Ireland, and the variability of those prices. The simulations also suggest that while increased interconnection may reduce carbon dioxide emissions in Ireland, Great Britain would experience an increase in emissions, resulting in total emissions remaining almost unchanged. The studies suggest that increased interconnection would not reduce excess wind generation. This is because under unit commitment techniques which incorporate wind power forecasts in the scheduling decisions, wind curtailment is minimal even with low levels of interconnection. As would be expected an increase in interconnection should improve system adequacy considerably with a significant reduction in the number of hours when the load and reserve constraints are not met. (author)

  2. A study to solve the variability of wind generation through integration of large-scale hydraulic generation; Um estudo para resolver a variabilidade da geracao eolica atraves da integracao em larga escala com geracao hidraulica

    Energy Technology Data Exchange (ETDEWEB)

    Emmerik, Emanuel Leonardus van; Steinberger, Johann Michael; Aredes, Mauricio [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEE/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Eletrica

    2010-07-01

    The optimal deployment of wind generation with the hydro generation is being investigated as a viable option to assist in resolving the constraints coming ahead as a consequence of the tendency of recovery in the Brazilian Amazon basin for expansion of generating facilities. It is in the validity of this research that this work is focused. The value is shown of feasibility studies of using water power generation to offset the variability of wind generation when it is deployed on a large scale. Preliminary results are presented for the variability of wind generation at various cycles, the variability of the availability of hydropower. (author)

  3. Combustion noise

    Science.gov (United States)

    Strahle, W. C.

    1977-01-01

    A review of the subject of combustion generated noise is presented. Combustion noise is an important noise source in industrial furnaces and process heaters, turbopropulsion and gas turbine systems, flaring operations, Diesel engines, and rocket engines. The state-of-the-art in combustion noise importance, understanding, prediction and scaling is presented for these systems. The fundamentals and available theories of combustion noise are given. Controversies in the field are discussed and recommendations for future research are made.

  4. 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.

  5. 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...

  6. Incorporation of a wind generator model into a dynamic power flow analysis; Incorporacion de un modelo de generador eolico al analisis de flujos dinamicos de potencia

    Energy Technology Data Exchange (ETDEWEB)

    Angeles Camacho, C.; Banuelos Ruedas, F. [Instituto de Ingenieria, Universidad Nacional Autonoma de Mexico (Mexico)]. E-mail: cangelesc@iingen.unam.mx; fbanuelosr@iingen.unam.mx

    2011-07-15

    Wind energy is nowadays one of the most cost-effective and practical options for electric generation from renewable resources. However, increased penetration of wind generation causes the power networks to be more depend on, and vulnerable to, the varying wind speed. Modeling is a tool which can provide valuable information about the interaction between wind farms and the power network to which they are connected. This paper develops a realistic characterization of a wind generator. The wind generator model is incorporated into an algorithm to investigate its contribution to the stability of the power network in the time domain. The tool obtained is termed dynamic power flow. The wind generator model takes on account the wind speed and the reactive power consumption by induction generators. Dynamic power flow analysis is carried-out using real wind data at 10-minute time intervals collected for one meteorological station. The generation injected at one point into the network provides active power locally and is found to reduce global power losses. However, the power supplied is time-varying and causes fluctuations in voltage magnitude and power flows in transmission lines. [Spanish] La energia eolica es hoy en dia una de las opciones mas efectivas y practicas para la generacion de electricidad a partir de energias renovables. Sin embargo, el incremento de la penetracion de energia eolica provoca que los sistemas de potencia se vuelvan mas dependientes y vulnerables a las variaciones de la velocidad del viento. El modelado es una herramienta que provee informacion valiosa de la interaccion dinamica entre las turbinas eolicas y las redes de potencia a las que se conectan. El presente articulo desarrolla una caracterizacion realista de un modelo de la turbina eolica. El modelo de la turbina eolica se incorpora a un algoritmo para el analisis de su contribucion a la estabilidad de una red electrica en el dominio del tiempo. La herramienta obtenida se conoce como flujos

  7. Minimizing noise-temperature measurement errors

    Science.gov (United States)

    Stelzried, C. T.

    1992-01-01

    An analysis of noise-temperature measurement errors of low-noise amplifiers was performed. Results of this analysis can be used to optimize measurement schemes for minimum errors. For the cases evaluated, the effective noise temperature (Te) of a Ka-band maser can be measured most accurately by switching between an ambient and a 2-K cooled load without an isolation attenuator. A measurement accuracy of 0.3 K was obtained for this example.

  8. High level white noise generator

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  9. High level white noise generator

    Science.gov (United States)

    Borkowski, Casimer J.; Blalock, Theron V.

    1979-01-01

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

  10. Noise Protection

    Science.gov (United States)

    1980-01-01

    Environmental Health Systems puts forth an increasing effort in the U.S. to develop ways of controlling noise, particularly in industrial environments due to Federal and State laws, labor union insistence and new findings relative to noise pollution impact on human health. NASA's Apollo guidance control system aided in the development of a noise protection product, SMART. The basis of all SMART products is SMART compound a liquid plastic mixture with exceptional energy/sound absorbing qualities. The basic compound was later refined for noise protection use.

  11. Assessment of wind energy potential and cost estimation of wind-generated electricity at hilltops surrounding the city of Maroua in Cameroon

    Science.gov (United States)

    Kaoga, Dieudonné Kidmo; Bogno, Bachirou; Aillerie, Michel; Raidandi, Danwe; Yamigno, Serge Doka; Hamandjoda, Oumarou; Tibi, Beda

    2016-07-01

    In this work, 28 years of wind data, measured at 10m above ground level (AGL), from Maroua meteorological station is utilized to assess the potential of wind energy at exposed ridges tops of mountains surrounding the city of Maroua. The aim of this study is to estimate the cost of wind-generated electricity using six types of wind turbines (50 to 2000 kW). The Weibull distribution function is employed to estimate Weibull shape and scale parameters using the energy pattern factor method. The considered wind shear model to extrapolate Weibull parameters and wind profiles is the empirical power law correlation. The results show that hilltops in the range of 150-350m AGL in increments of 50, fall under Class 3 or greater of the international system of wind classification and are deemed suitable to outstanding for wind turbine applications. A performance of the selected wind turbines is examined as well as the costs of wind-generated electricity at the considered hilltops. The results establish that the lowest costs per kWh are obtained using YDF-1500-87 (1500 kW) turbine while the highest costs are delivered by P-25-100 (90 kW). The lowest costs (US) per kWh of electricity generated are found to vary between a minimum of 0.0294 at hilltops 350m AGL and a maximum of 0.0366 at hilltops 150m AGL, with corresponding energy outputs that are 6,125 and 4,932 MWh, respectively. Additionally, the matching capacity factors values are 38.05% at hilltops 150m AGL and 47.26% at hilltops 350m AGL. Furthermore, YDF-1500-87 followed by Enercon E82-2000 (2000 kW) wind turbines provide the lowest cost of wind generated electricity and are recommended for use for large communities. Medium wind turbine P-15-50 (50 kW), despite showing the best coefficients factors (39.29% and 48.85% at hilltops 150 and 350m AGL, in that order), generates electricity at an average higher cost/kWh of US0.0547 and 0.0440 at hilltops 150 and 350m AGL, respectively. P-15-50 is deemed a more advantageous option

  12. Ambient environment in the coal mining complexes

    International Nuclear Information System (INIS)

    Singh, V.K.

    1998-01-01

    Environment is all pervading and therefore associated with all individuals. The ambient environment with respect to any activity lies a little outside and the receiving body outside the active zone denotes ambient environment. Basically, air quality and noise level are two physical ingredients whose assessment gives an idea of impact on the ambience. Though largely blamed for polluted conditions, the general ambient conditions in the coal fields do not show a tardy image. Being a low level dispersion industry, its impact remains concentrated in the active core zone. This has been brought out here. The paper presents the status of air quality, and noise level in some coal fields in India. It also discloses a brighter future and sustainable development due to increased concern for environment. (author)

  13. An inexpensive sensor for noise.

    Science.gov (United States)

    Hallett, Laura; Tatum, Marcus; Thomas, Geb; Sousan, Sinan; Koehler, Kirsten; Peters, Thomas

    2018-02-08

    Noise is a pervasive workplace hazard that varies spatially and temporally. The cost of direct-reading instruments for noise hampers their use in a network. The objectives for this work were to (1) develop an inexpensive noise sensor (noise sensors for use in an inexpensive sensor network. The inexpensive noise sensor consists of an electret condenser microphone, an amplifier circuit, and a microcontroller with a small form factor (28 mm by 47 mm by 9 mm) than can be operated as a stand-alone unit. Laboratory tests were conducted to evaluate 50 of the new sensors at 5 sound levels: (1) ambient sound in a quiet office; (2) a pink noise test signal from 65 to 85 dBA in 10 dBA increments; and (3) 94 dBA using a SLM calibrator. Ninety-four percent of the noise sensors (n = 46) were within ± 2 dBA of the SLM for sound levels from 65 dBA to 94 dBA. As sound level increased, bias decreased, ranging from 18.3% in the quiet office to 0.48% at 94 dBA. Overall bias of the sensors was 0.83% across the 75 dBA to 94 dBA range. These sensors are available for a variety of uses and can be customized for many applications, including incorporation into a stationary sensor network for continuous monitoring of noise in manufacturing environments.

  14. Environmental Noise

    Science.gov (United States)

    Rumberg, Martin

    Environmental noise may be defined as unwanted sound that is caused by emissions from traffic (roads, air traffic corridors, and railways), industrial sites and recreational infrastructures, which may cause both annoyance and damage to health. Noise in the environment or community seriously affects people, interfering with daily activities at school, work and home and during leisure time.

  15. 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.

  16. 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.

  17. Long-term Self-noise Estimates of Seismic Sensors From a High-noise Vault

    Science.gov (United States)

    Hicks, S. P.; Goessen, S.; Hill, P.; Rietbrock, A.

    2017-12-01

    To understand the detection capabilities of seismic stations and for reducing biases in ambient noise imaging, it is vital to assess the contribution of instrument self-noise to overall site noise. Self-noise estimates typically come from vault installations in continental interiors with very low ambient noise levels. However, this approach restricts the independent assessment of self-noise by individual end-users to assess any variations in their own instrument pools from nominal specifications given by manufacturers and from estimations given in comparative test papers. However, the calculation method should be adapted to variable installation conditions. One problem is that microseism noise can contaminate self-noise results caused by instrument misalignment errors or manufacturing limits; this effect becomes stronger where ambient noise is higher. Moreover, due to expected stochastic and time-varying sensor noise, estimates based on hand-picking small numbers of data segments may not accurately reflect true self-noise. We report on results from a self-noise test experiment of Güralp seismic instruments (3T, 3ESPC broadband seismometers, Fortis strong motion accelerometer) that were installed in the sub-surface vault of the Eskdalemuir Seismic Observatory in Scotland, UK over the period October 2016-August 2017. Due to vault's proximity to the ocean, secondary microseism noise is strong, so we efficiently compute the angle of misalignment that maximises waveform coherence with a reference sensor. Self-noise was calculated using the 3-sensor correlation technique and we compute probability density functions of self-noise to assess its spread over time. We find that not correcting for misalignments as low as 0.1° can cause self-noise to be artificially higher by up to 15 dB at frequencies of 0.1-1 Hz. Our method thus efficiently removes the effect of microseism contamination on self-noise; for example, it restores the minimum noise floor for a 360s - 50 Hz 3T to

  18. 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.

  19. Impact of noise on hearing amongst commercial motor bike riders in ...

    African Journals Online (AJOL)

    The ambient noise level and noise-induced hearing impairment (NIHI) in 200 motorbike riders from six motorbike parks were evaluated. All were males aged between 20- 62 years. Subjects were sampled using a cluster sampling technique. Parameters measured were environmental noise using the noise meter (peters) ...

  20. Method for measuring self-noise of vector hydrophones

    Science.gov (United States)

    Li, Zhi; Chen, Hongjuan

    2017-09-01

    The Vector Hydrophone (VH) is widely used to remotely detect underwater targets. Accurately measuring the self-noise of the VH provides an important basis for evaluating the performance of the detection system in which it is utilized, since the ability to acquire weak signals is determined by the VH self-noise level. To accurately measure the VH self-noise level in actual working conditions, the Dual-channel Transfer Function Method (DTFM) is proposed to reduce ambient background noise interference. In this paper, the underlying principles of DTFM in reducing ambient background noise is analyzed. The numerical simulations to determine the influence of ambient background noise, and the sensitivity difference of the two VHs on the measurement results are studied. The results of measuring the VH self-noise level in a small laboratory water tank by using DTMF indicate that ambient background noise interference can be reduced effectively by employing DTMF, more accurate self-noise level can be obtained as well. The DTMF provides an effective method for accurately measuring the self-noise level of VHs and also provides technical support for the practical application of the VH in underwater acoustics.

  1. Noise-Induced Hearing Loss - A Preventable Disease?

    DEFF Research Database (Denmark)

    Frederiksen, Thomas W.; Ramlau-Hansen, Cecilia H.; Stokholm, Zara A.

    2017-01-01

    statistically significant among baseline participants with first exposure before the 1980s (odds ratio: 1.90, 95% CI: 1.11; 3.22). CONCLUSIONS: We observed declining industrial noise levels, increased use of HPD and no significant impact on hearing thresholds from current ambient industrial noise levels, which...... insignificant, inverse association between higher ambient cumulative noise exposure and poorer hearing (-0.10 dB hearing threshold shift per dB-year (95% confidence interval (CI): -0.36; 0.16)). The risk of hearing loss seemed to increase with earlier first year of noise exposure, but odds ratios were only...

  2. Drone noise

    Science.gov (United States)

    Tinney, Charles; Sirohi, Jayant; University of Texas at Austin Team

    2017-11-01

    A basic understanding of the noise produced by single and multirotor drones operating at static thrust conditions is presented. This work acts as an extension to previous efforts conducted at The University of Texas at Austin (Tinney et al. 2017, AHS Forum 73). Propeller diameters ranging from 8 inch to 12 inch are examined for configurations comprising an isolated rotor, a quadcopter configuration and a hexacopter configuration, and with a constant drone pitch of 2.25. An azimuthal array of half-inch microphones, placed between 2 and 3 hub-center diameters from the drone center, are used to assess the acoustic near-field. Thrust levels, acquired using a six degree-of-freedom load cell, are then used to correlate acoustic noise levels to aerodynamic performance for each drone configuration. The findings reveal a nearly logarithmic increase in noise with increasing thrust. However, for the same thrust condition, considerable noise reduction is achieved by increasing the number of propeller blades thereby reducing the blade passage frequency and both the thickness and loading noise sources that accompany it.

  3. Adaptive Suppression of Noise in Voice Communications

    Science.gov (United States)

    Kozel, David; DeVault, James A.; Birr, Richard B.

    2003-01-01

    A subsystem for the adaptive suppression of noise in a voice communication system effects a high level of reduction of noise that enters the system through microphones. The subsystem includes a digital signal processor (DSP) plus circuitry that implements voice-recognition and spectral- manipulation techniques. The development of the adaptive noise-suppression subsystem was prompted by the following considerations: During processing of the space shuttle at Kennedy Space Center, voice communications among test team members have been significantly impaired in several instances because some test participants have had to communicate from locations with high ambient noise levels. Ear protection for the personnel involved is commercially available and is used in such situations. However, commercially available noise-canceling microphones do not provide sufficient reduction of noise that enters through microphones and thus becomes transmitted on outbound communication links.

  4. Output Power Smoothing and Voltage Regulation of a Fixed Speed Wind Generator in the Partial Load Region Using STATCOM and a Pitch Angle Controller

    Directory of Open Access Journals (Sweden)

    Kanasottu Anil Naik

    2017-12-01

    Full Text Available The output power and terminal voltage of the fixed speed induction generator fluctuate in the partial load region where the wind speed is below the rated vale, resulting in fluctuations in the grid frequency and voltage. In this paper, a novel pitch angle control strategy has developed by introducing an exponential moving average (EMA concept from which the controller reference power (signal can be set for below-rated wind speeds. Therefore, the employed pitch angle controller together with static synchronous compensator (STATCOM, named the unified voltage and pitch angle controller (UVPC, addresses the objective of smoothing the output power and terminal voltage regulation of a wind generator, subjected to below-rated wind speed variations. Moreover, an interval type-2 fuzzy logic technique has incorporated in the pitch angle controller design, since it is more efficient in handling the uncertainties in membership functions and rules than its traditional fuzzy logic counterparts. Simulation results clearly show that the proposed UVPC effectively smoothens out the generator output power and also regulates the terminal voltage at its constant magnitude.

  5. A robust predictive current controller for healthy and open-circuit faulty conditions of five-phase BLDC drives applicable for wind generators and electric vehicles

    International Nuclear Information System (INIS)

    Salehi Arashloo, Ramin; Salehifar, Mehdi; Romeral, Luis; Sala, Vicent

    2015-01-01

    Highlights: • Model predictive deadbeat control of generator stator phase currents. • Fault tolerant control of five-phase BLDC generator. • Control of stator phase currents under normal and open-circuit faulty conditions. • MATLAB simulation and experimental verification of proposed control method. • Verification of robustness and fast respond of proposed controlling method. - Abstract: Fault tolerant control of five-phase brushless direct current (BLDC) machines is gaining more importance in high-safety applications such as offshore wind generators and automotive industries. In many applications, traditional controllers (such as PI controllers) are used to control the stator currents under faulty conditions. These controllers have good performance with dc signals. However, in the case of missing one or two of the phases, appropriate reference currents of these machines have oscillatory dynamics both in phase- and synchronous-reference frames. Non-constant nature of these reference values requires the implication of fast current controllers. In this paper, model predictive deadbeat controllers are proposed to control the stator currents of five-phase BLDC machines under normal and faulty conditions. Open circuit fault is considered for both one and two stator phases, and the behaviour of proposed controlling method is evaluated. This evaluation is generally focused on first, sensitivity of proposed controlling method and second, its speed in following reference current values under transient states. Proposed method is simulated and is verified experimentally on a five-phase BLDC drive

  6. Passive Acoustic Thermometry Using Low-Frequency Deep Water Noise

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Passive Acoustic Thermometry Using Low-Frequency Deep... thermometry using Cross-correlation processing of deep water ambient noise. OBJECTIVE Our previous research effort has demonstrated that coherent... thermometry using low-frequency deep water ambient noise recorded on the global IMS- CTBTO network Results from this study are expected to help guide the

  7. 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.

  8. 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

  9. 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...

  10. Automated Processing Workflow for Ambient Seismic Recordings

    Science.gov (United States)

    Girard, A. J.; Shragge, J.

    2017-12-01

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

  11. 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....

  12. Impact of noise and air pollution on pregnancy outcomes

    NARCIS (Netherlands)

    Gehring, Ulrike|info:eu-repo/dai/nl/304831344; 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

  13. An atmospheric turbulence model for spatiotemporal variability of geographically-diverse, aggregated wind-generated electricity to accelerate wide-scale wind energy deployment (Invited)

    Science.gov (United States)

    Lundquist, J. K.; Handschy, M.

    2013-12-01

    During the year 2012, the cumulative wind power capacity installed in the United States could provide roughly 4.4% of electricity demand. Although the wind resource can provide many times over the entire US electrical needs, and costs for onshore wind deployment are continually dropping, the variability of the wind represents one of the greatest remaining barriers to wide-scale wind deployment. This study focuses on the nature of this variability. We quantify the axiom 'geographic diversity reduces variability' (of wind generation) by relating resource variability characteristics to the well-understood physical phenomena of turbulence in the Earth's atmosphere. Many existing studies focus on datasets of a few years' duration in a particular geographic area; such results are difficult to generalize. Our approach builds on the fundamental nonlinear characteristics of turbulence in the atmosphere to characterize wind speed and power generation correlations between wind plants from local to continental scales. The resulting general principles enable estimation of the benefits of geographic aggregation absent detailed site-specific historical data, thereby enabling more efficient transmission grid models, expediting transmission plans, and providing a framework for evaluating the requirements and benefits of electric storage at higher wind penetrations. To validate these general principles, we compare them to observed inter-station correlations in a number of wind-speed data sets, including a 40-year Canadian dataset that spans the continent of North America, as well as shorter-duration datasets in smaller regions within the United States. This presentation will present general rules for the dependence of correlation between wind turbines on separation and time scale. We suggest these general rules could help shift renewable integration planning from simulation towards optimization.

  14. Plug-in hybrid electric vehicles as a way to maximize the integration of variable renewable energy in power systems: The case of wind generation in northeastern Brazil

    International Nuclear Information System (INIS)

    Soares MC Borba, Bruno; Szklo, Alexandre; Schaeffer, Roberto

    2012-01-01

    Several studies have proposed different tools for analyzing the integration of variable renewable energy into power grids. This study applies an optimization tool to model the expansion of the electric power system in northeastern Brazil, enabling the most efficient dispatch of the variable output of the wind farms that will be built in the region over the next 20 years. The expected combined expansion of wind generation with conventional inflexible generation facilities, such as nuclear plants and run-of-the-river hydropower plants, poses risks of future mismatch between supply and demand in northeastern Brazil. Therefore, this article evaluates the possibility of using a fleet of plug-in hybrid electric vehicles (PHEVs) to regularize possible energy imbalances. Findings indicate that a dedicated fleet of 500 thousand PHEVs in 2015, and a further 1.5 million in 2030, could be recharged overnight to take advantage of the surplus power generated by wind farms. To avoid the initial costs of smart grids, this article suggests, as a first step, the use of a governmental PHEV fleet that allows fleet managers to control battery charging times. Finally, the study demonstrates the advantages of optimizing simultaneously the power and transport sectors to test the strategy suggested here. -- Highlights: ► We evaluated the use of plug-in hybrid electric vehicles (PHEV) to regularize possible energy imbalances in northeastern Brazil. ► This imbalance might result from the large-scale wind power penetration along with conventional inflexible power plants in the region. ► We adapted the MESSAGE optimization tool to the base conditions of the Brazilian power system. ► 500 thousand PHEVs in 2015 and 1.5 million in 2030 could be recharged taking advantage of wind energy surplus.

  15. The future is 'ambient'

    Science.gov (United States)

    Lugmayr, Artur

    2006-02-01

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

  16. Occupational Noise Exposure

    Science.gov (United States)

    ... Safety and Health Topics / Occupational Noise Exposure Occupational Noise Exposure This page requires that javascript be enabled ... interprets the signal as sound. x What is noise? Noise and vibration are both fluctuations in the ...

  17. 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....

  18. Yesterday's noise - today's signal

    International Nuclear Information System (INIS)

    Serdula, K.J.

    1978-01-01

    Plant performance can be improved by noise analysis. This paper describes noise characteristics, imposed noise and response functions, a case history of cost benefits derived from application of noise analysis techniques, areas for application of noise analysis techniques with special reference to the Gentilly-1 nuclear generating station, and the validity of noise measurement results. (E.C.B.)

  19. Noise Abatement

    Science.gov (United States)

    1983-01-01

    SMART, Sound Modification and Regulated Temperature compound, is a liquid plastic mixture with exceptional energy and sound absorbing qualities. It is derived from a very elastic plastic which was an effective noise abatement material in the Apollo Guidance System. Discovered by a NASA employee, it is marketed by Environmental Health Systems, Inc. (EHS). The product has been successfully employed by a diaper company with noisy dryers and a sugar company with noisy blowers. The company also manufactures an audiometric test booth and acoustical office partitions.

  20. Licenciamento ambiental e sustentabilidade

    Directory of Open Access Journals (Sweden)

    Marcelo Macedo Valinhas

    2011-12-01

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

  1. Quantum Noise

    International Nuclear Information System (INIS)

    Beenakker, C W J

    2005-01-01

    Quantum Noise is advertised as a handbook, and this is indeed how it functions for me these days: it is a book that I keep within hand's reach, ready to be consulted on the proper use of quantum stochastic methods in the course of my research on quantum dots. I should point out that quantum optics, the target field for this book, is not my field by training. So I have much to learn, and find this handbook to be a reliable and helpful guide. Crispin Gardiner previously wrote the Handbook of Stochastic Methods (also published by Springer), which provides an overview of methods in classical statistical physics. Quantum Noise, written jointly with Peter Zoller, is the counterpart for quantum statistical physics, and indeed the two books rely on each other by frequent cross referencing. The fundamental problem addressed by Quantum Noise is how the quantum dynamics of an open system can be described statistically by treating the environment as a source of noise. This is a general problem in condensed matter physics (in particular in the context of Josephson junctions) and in quantum optics. The emphasis in this book in on the optical applications (for condensed matter applications one could consult Quantum Dissipative Systems by Ulrich Weiss, published by World Scientific). The optical applications centre around the interaction of light with atoms, where the atoms represent the open system and the light is the noisy environment. A complete description of the production and detection of non-classical states of radiation (such as squeezed states) can be obtained using one of the equivalent quantum stochastic formulations: the quantum Langevin equation for the field operators (in either the Ito or the Stratonovich form), the Master equation for the density matrix, or the stochastic Schroedinger equation for the wave functions. Each formulation is fully developed here (as one would expect from a handbook), with detailed instructions on how to go from one to the other. The

  2. Jet Noise Scaling in Dual Stream Nozzles

    Science.gov (United States)

    Khavaran, Abbas; Bridges, James

    2010-01-01

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

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

    NARCIS (Netherlands)

    Wesselink, J.M.

    2009-01-01

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

  4. On the Retrieval of the Directional Scattering Matrix from Directional Noise

    NARCIS (Netherlands)

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

    2013-01-01

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

  5. Underwater noise from a wave energy converter

    DEFF Research Database (Denmark)

    Tougaard, Jakob

    in full operation and start and stop of the converter. Median broad band (10 Hz – 20 kHz) sound pressure level (Leq) was 123 dB re. 1 Pa, irrespective of status of the wave energy converter (stopped, running or starting/stopping). The most pronounced peak in the third-octave spectrum was in the 160 Hz...... band during start and stop of the converter, attributed to the hydraulic pump responsible for lifting and lowering the absorbers. Less pronounced, but still statistically significant differences were seen in the bands 125, 160, 200 and 250 Hz when operation and ambient were compared. No statistically...... significant noise above ambient could be detected above the 250 Hz band. The absolute increase in noise above ambient was very small. L50 third-octave levels in the four bands with the converter running were thus only 1-2 dB above ambient L50 levels. The noise recorded 25 m from the wave energy converter...

  6. Underwater Noise Modeling in Lithuanian Area of the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Donatas Bagočius

    2017-09-01

    Full Text Available Along with rising awareness of public and scientific societies about environmental and ecological impacts of underwater noise, the need for underwater noise modelling in the shallow Lithuanian area of Baltic Sea emerged. Marine Strategy Framework Directive issues regarding underwater noise indicators refers to possibility of evaluation of Good Environmental State using underwater noise measurements as well as possibility to model underwater noise. Main anthropogenic underwater noise contributor in the Seas is the shipping lanes as known due to date, with no exclusion of Lithuanian Baltic Sea area. In this manuscript, it is presented the methods of development of simplistic underwater ambient noise model purposed for computation of underwater soundscape in shallow area of the Lithuanian Baltic Sea.

  7. Bayesian Ambient Noise Inversion for Geoacoustic Uncertainty Estimation

    Science.gov (United States)

    2013-09-30

    are generally not available for non-linear problems, Markov chain Monte Carlo ( MCMC ) methods are used to sample from this distribution.4 In this...APPROACH Traditional investigation of seabed sediment properties has relied heavily on direct measurements, such as core sampling and geo-probes...for numerical estimation of the posterior probability density (PPD) over the geoacoustic parameters of interest: Since analytical solutions for the PPD

  8. Noise and Hearing Protection

    Science.gov (United States)

    ... ENTCareers Marketplace 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 ...

  9. 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.

  10. 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....

  11. An investigation of ambient gameplay

    OpenAIRE

    Eyles, Mark

    2012-01-01

    Inspired by Brian Eno's ambient music, which is persistent and supports different levels of engagement, this research explores ambient gameplay in computer, video and pervasive games. Through the creation of original games containing ambient gameplay and looking for ambient gameplay in existing commercial games, this research focuses on gameplay that supports a range of depths of player engagement. This research is not concerned with ambient intelligent environments or other technologies that...

  12. Ambient oxygen promotes tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Ho Joong Sung

    2011-05-01

    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.

  13. El ambiente social

    Directory of Open Access Journals (Sweden)

    Henry Granada

    2001-01-01

    Full Text Available Con el título de« Ambiente Social» se quiere enfatizar que el concepto de Ambiente no se agota en lo ecológico (físico-biótico. Así mismo, dentro lo psicosocial, la noción de territorio adquiere importancia y otorga significación a la «experiencia ambiental», ya que abre ventanas hacia la comprensión de actividades como el ordenamiento territorial y a la mediación de las dimensiones psicológica, social y cultural del espacio. Finalmente, aunque el ordenamiento del territorio suele enfocarse desde los componentes sociopolíticos y económicos con el ánimo de planificación, el componente psicosocial traduce aspectos del ordenamiento dentro de la vida cotidiana y relaciona nociones como identidad y arraigo, entre otras.

  14. Ambiente, patrimonio y turismo

    OpenAIRE

    Mantero, Juan Carlos

    2003-01-01

    El tema de la conferencia asignado por los responsables del Tercer Congreso Latinoamericano de Investigación Turística supuso asumir la problemática de la interacción ambiente patrimonio turismo para realizar una reflexión que a partir de la definición de tales nociones permitiera acceder a una reflexión respecto de su significación cultural en la comunidad. El patrimonio de la comunidad comprende el ambiente e incluye la naturaleza y la cultura, del ayer y del presente, en su dimensión tangi...

  15. Active Noise Control for Dishwasher noise

    Science.gov (United States)

    Lee, Nokhaeng; Park, Youngjin

    2016-09-01

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

  16. Non-Markovian noise

    International Nuclear Information System (INIS)

    Fulinski, A.

    1994-01-01

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

  17. assessment of noise pollutio noise pollutio noise pollution

    African Journals Online (AJOL)

    eobe

    1DEPARTMENT OF WATER RESOURCES ... challenges. Symptoms of short or long periods exposure to noise include auditory effects such auditory fatigue and hearing loss, and indirect n auditory effects such as speech interfere .... ASSESSMENT OF NOISE POLLUTION FROM SAWMILL ACTIVITIES IN ILORIN, NIGERIA.

  18. assessment of noise pollutio noise pollutio noise pollution

    African Journals Online (AJOL)

    eobe

    This study examine. This study examined noise pollution pollution pollution from sawmillin from sawmillin using HD600 digital data l using HD600 digital data logging sound level me ogging sound level me designed to elicit noise related information. The res sawmills was 58.1 sawmills was 58.1-64.86 dB(A) while machine ...

  19. Meio ambiente e literatura

    Directory of Open Access Journals (Sweden)

    Marli de Oliveira Fantini Scarpelli

    2007-06-01

    Full Text Available Este artigo busca reconhecer alguns pontos de tangência entre os romances Vidas secas, de Graciliano Ramos, As cidades invisíveis, de Italo Calvino, e Grande sertão: veredas, de Guimarães Rosa, sobretudo no que respeita às relações modalizantes entre literatura e meio ambiente. Em meio à diversidade temática das obras indicadas, subjaz o tema da consciência ambiental, que, nas últimas décadas, vem recebendo a crescente adesão não apenas de ambientalistas, mas também de intelectuais, políticos, escritores. O foco na degradação ambiental, no alerta implícito acerca das precárias condições de vida futura em nosso planeta revela um dos nucleares e contundentes problemas a desafiar a agenda contemporânea. Nesse sentido, revela-se paradigmático o “lugar-sertão” rosiano, que, ao difundir seu território, seus valores e denúncias, patenteia uma concepção ambiental inovadora e reticular, em estreito diálogo com as atuais pesquisas interdisciplinares sobre o tema, as quais deveriam doravante guardar, em seu horizonte de expectativa, os paradigmas, as perspectivas e os equacionamentos que alicerçam as artes em geral e a literatura em particular.

  20. Advancing Environmental Noise Pollution Analysis in Urban Areas by Considering the Variation of Population Exposure in Space and Time

    Science.gov (United States)

    Freire, S.; Gomes, N.

    2013-05-01

    Ambient noise is a subtle form of pollution in large urban areas, degrading human health and well-being. In Europe, directives require that urban environmental noise be measured and mapped for the main periods of the daily cycle. Subsequent analyses of human exposure to noise in those periods is usually conducted using resident (i.e., nighttime) population from the census and assuming constant densities within the enumeration units. However, population distribution and densities vary considerably from night to day in metropolitan areas, and disregard for that process results in gross misestimation of exposure to ambient noise in the daytime period. This study considers the spatio-temporal variation of population distribution in assessing exposure to ambient noise in a major urban area, the city of Lisbon, Portugal. Detailed and compatible day- and nighttime population distribution maps were used, developed by means of "intelligent dasymetric mapping". After categorizing noise levels in existing maps in each period, classified according to current legislation, human exposure to ambient noise was assessed with temporally matching population surfaces. Population exposure to noise in 2000 and 2009 was compared and further analyzed in regards to main source of noise, i.e. road traffic vs. aircraft.. Results show that human exposure to noise shifts substantially in time and space, with a significant increase in exposed population from the nighttime to daytime period, especially in the higher noise levels. This is due to the combined effects of the daily variation of noise patterns and population distribution.

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

    NARCIS (Netherlands)

    Witvliet, Ben A.; van Maanen, Erik; Bentum, Marinus Jan; Slump, Cornelis H.; Schiphorst, Roelof

    2015-01-01

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

  2. 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.

  3. Study on Noise Prediction Model and Control Schemes for Substation

    Science.gov (United States)

    Gao, Yang; Liu, Songtao

    2014-01-01

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

  4. Aviation noise effects

    Science.gov (United States)

    Newman, J. S.; Beattie, K. R.

    1985-03-01

    This report summarizes the effects of aviation noise in many areas, ranging from human annoyance to impact on real estate values. It also synthesizes the findings of literature on several topics. Included in the literature were many original studies carried out under FAA and other Federal funding over the past two decades. Efforts have been made to present the critical findings and conclusions of pertinent research, providing, when possible, a bottom line conclusion, criterion or perspective. Issues related to aviation noise are highlighted, and current policy is presented. Specific topic addressed include: annoyance; Hearing and hearing loss; noise metrics; human response to noise; speech interference; sleep interference; non-auditory health effects of noise; effects of noise on wild and domesticated animals; low frequency acoustical energy; impulsive noise; time of day weightings; noise contours; land use compatibility; and real estate values. This document is designed for a variety of users, from the individual completely unfamiliar with aviation noise to experts in the field.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  6. Indicadores de salud ambiental

    Directory of Open Access Journals (Sweden)

    Manuel Posada de la Paz

    2004-12-01

    Full Text Available Esta ponencia presenta una visión general del proyecto de Indicadores de Salud Ambiental, coordinado por la OMS a nivel internacional y liderado por el Centro de Investigación sobre el Síndrome del Aceite Tóxico y Enfermedades Raras (CISATER en España. En ella se describen los objetivos del proyecto, las gestiones realizadas y los resultados obtenidos durante la fase de viabilidad de este proyecto. El proyecto consiste en el establecimiento de un sistema de información sobre salud ambiental que permita desarrollar una vigilancia de los factores ambientales determinantes de los estados de salud, realizar comparaciones internacionales, elaborar políticas de acción, así como facilitar la comunicación con la ciudadanía. La OMS desarrolló una metodología para el desarrollo de estos indicadores dentro del marco conceptual de información ambiental DPSEEA (Fuerzas impulsoras, Presión, Estado, Exposición, Efecto, Acción y seleccionó un total de 55 indicadores (que incluyen 168 variables sobre 10 áreas de la salud ambiental. Durante la fase de viabilidad se predijo que podrían obtenerse el 89% de los indicadores. Sin embargo la recolección de los datos supuso muchas dificultades debido a la incompatibilidad de algunas variables en los sistemas de información españoles con las variables definidas por la OMS. A nivel de gestión del proyecto, la mayor dificultad radica en la disparidad de responsabilidades en materia de medio ambiente y salud entre las instituciones españolas. Además de la aportación técnica a la salud ambiental en España, un valor añadido de este proyecto ha sido el establecimiento de líneas de colaboración estrechas con los responsables de los diferentes Ministerios implicados.

  7. 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...

  8. 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

  9. Planejamento ambiental do turismo

    OpenAIRE

    Clauciana Schmidt Bueno de Moraes

    2002-01-01

    O planejamento ambiental municipal através da metodologia elaborada nesta pesquisa visa contribuir para a adequação das características físico-ambientais, sócio-econômicas, político-administrativas e histórico-culturais do município relacionado com as atividades turísticas. Neste sentido, a conscientização voltada para a conservação através da educação ambiental se torna indispensável para organizar o espaço turístico, direcionado à importância de uma satisfação das necessidades das gerações ...

  10. Helicopter Noise And Noise Abatement Procedures

    Directory of Open Access Journals (Sweden)

    Borivoj Galović

    2004-03-01

    Full Text Available The helicopter generated noise at and around the airports islower than the noise generated by aeroplanes, since their numberof operations, i. e. the number of takeoffs and landings ismuch lower than the takeoffs and landings of the aeroplanes.Out of some hundred operations a day, helicopters participatewith approximately 15%, but the very impact of noise is by nomeans negligible, since the number of helicopter flights aboveurban areas is constantly increasing.This paper attempts to analyse this phenomenon and thetype of helicopter generated noise, its negative impacts, to explainthe flight procedures and the operative procedures duringtakeoff, landing and overflight of helicopters in operations inthe vicinity and outside airports, as well as the methods of measuringand determining the limit of noise [eve~ and the resultingproblems.

  11. MEIO AMBIENTE E DESENVOLVIMENTO

    Directory of Open Access Journals (Sweden)

    Suely Salgueiro Chacon

    2009-12-01

    Full Text Available 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 desenvolvimento. A humanidade tem que regredir”. Este artigo apresenta a evolução do conceito de desenvolvimento econômico sob a ótica da sustentabilidade, e interliga temas como: o ambientalismo, aglutinador de distintos pensamentos sobre as relações entre a sociedade e a natureza; o movimento ambiental, a fundamentar a disseminação do conceito de desenvolvimento sustentável, e a gestão ambiental, abordada como prática orientada pelo conceito de desenvolvimento sustentável.

  12. Noise Radar Technology Basics

    National Research Council Canada - National Science Library

    Thayaparan, T; Wernik, C

    2006-01-01

    .... In this report, the basic theory of noise radar design is treated. The theory supports the use of noise waveforms for radar detection and imaging in such applications as covert military surveillance and reconnaissance...

  13. NASA Jet Noise Research

    Science.gov (United States)

    Henderson, Brenda

    2016-01-01

    The presentation highlights NASA's jet noise research for 2016. Jet-noise modeling efforts, jet-surface interactions results, acoustic characteristics of multi-stream jets, and N+2 Supersonic Aircraft system studies are presented.

  14. Noise Gating Solar Images

    Science.gov (United States)

    DeForest, Craig; Seaton, Daniel B.; Darnell, John A.

    2017-08-01

    I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO

  15. Noise Reduction Techniques

    Science.gov (United States)

    Hallas, Tony

    There are two distinct kinds of noise - structural and color. Each requires a specific method of attack to minimize. The great challenge is to reduce the noise without reducing the faint and delicate detail in the image. My most-used and favorite noise suppression is found in Photoshop CS 5 Camera Raw. If I cannot get the desired results with the first choice, I will use Noise Ninja, which has certain advantages in some situations that we will cover.

  16. Salud ambiental: conceptos y actividades

    OpenAIRE

    Gonzalo A. Ordóñez

    2000-01-01

    La finalidad del trabajo es aportar información y propuestas conceptuales que faciliten la tarea de quienes tienen a su cargo la sistematización institucional de la salud ambiental. Se hace un análisis de la noción de "ambiente" para la cual se sugiere una definición, y se examina el lugar de la salud ambiental en el contexto de los problemas ambientales y sus vertientes "verde" y "azul". Se examinan denominaciones equivalentes de salud ambiental y se introducen los servicios de salud ambient...

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

    Science.gov (United States)

    Krahforst, Cecilia S.

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

  18. Equation for Combustion Noise

    Science.gov (United States)

    Liu, T. M.

    1982-01-01

    Mathematical relationship derived for interactions between turbulent flame and combustion noise. Relationship is rigorous theoretical correlation of combustion noise and combustion process. Establishes foundation for acoustic measurements as tool for investigating structure of turbulent flames. Mathematical relationship is expected to aid researchers in field of noise generated by combustion.

  19. Introductory guide to noise

    CSIR Research Space (South Africa)

    Ferreira, T.M

    1973-01-01

    Full Text Available The difference between sound and noise varies from one human being to another. Noise, then, is simply unwanted sound and to understand how it can be combatted we must know more about its nature. A guide of acceptable levels of noise are investigated....

  20. 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...

  1. Investigation of Noise Pollution in Restaurants in Morogoro ...

    African Journals Online (AJOL)

    The assessment of the present status of sound levels in seven restaurants at Morogoro municipality was studied. The indoor and outdoor ambient noise levels were measured twice a day, thrice a week for a period of two months by using digital sound level meter. In addition, questionnaires survey was used to assess ...

  2. Investigation of Noise Pollution in Restaurants in Morogoro ...

    African Journals Online (AJOL)

    MICHAEL

    ABSTRACT: The assessment of the present status of sound levels in seven restaurants at Morogoro municipality was studied. The indoor and outdoor ambient noise levels were measured twice a day, thrice a week for a period of two months by using digital sound level meter. In addition, questionnaires survey was used to ...

  3. Modelling traffic noise level on roadside traders at Wurukum market ...

    African Journals Online (AJOL)

    The model indicates high level of ambient noise which was attributed to intensive market activities from the background. The model was checked using Chi square test at 5% level of significance and coefficient of determin ation (R 2 =0.7216) which gave satisfactory results. A strategy of relocation and splitting the market ...

  4. Active noise control in a duct to cancel broadband noise

    Science.gov (United States)

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

    2017-09-01

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

  5. Classical noise, quantum noise and secure communication

    International Nuclear Information System (INIS)

    Tannous, C; Langlois, J

    2016-01-01

    Secure communication based on message encryption might be performed by combining the message with controlled noise (called pseudo-noise) as performed in spread-spectrum communication used presently in Wi-Fi and smartphone telecommunication systems. Quantum communication based on entanglement is another route for securing communications as demonstrated by several important experiments described in this work. The central role played by the photon in unifying the description of classical and quantum noise as major ingredients of secure communication systems is highlighted and described on the basis of the classical and quantum fluctuation dissipation theorems. (review)

  6. 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....

  7. Optical Johnson noise thermometry

    Science.gov (United States)

    Shepard, R. L.; Blalock, T. V.; Maxey, L. C.; Roberts, M. J.; Simpson, M. L.

    1989-01-01

    A concept is being explored that an optical analog of the electrical Johnson noise may be used to measure temperature independently of emissivity. The concept is that a laser beam may be modulated on reflection from a hot surface by interaction of the laser photons with the thermally agitated conduction electrons or the lattice phonons, thereby adding noise to the reflected laser beam. If the reflectance noise can be detected and quantified in a background of other noise in the optical and signal processing systems, the reflectance noise may provide a noncontact measurement of the absolute surface temperature and may be independent of the surface's emissivity.

  8. Ambient og intelligent teknologi

    DEFF Research Database (Denmark)

    Andersen, Peter Bøgh

     Dette notat handler om hvordan humanistisk og samfundsfaglig forskning i øjeblikket nyttiggøres ved udformning af IKT-anvendelser, der er indlejret i vor dagligdag i den forstand, at de indgår som et element i de aktiviteter, vi foretager på arbejdet eller i fritiden. Sådanne anvendelser kaldes ...... undertiden ambiente – noget der omslutter os på alle sider. Rapporten peger også på virkemidler som kan forbedre og øge en humanistisk og samfundsfaglig forskningsindsats....

  9. El periodismo ambiental

    OpenAIRE

    Grinberg, Miguel

    2008-01-01

    La problemática ambiental no posee una presencia estructurada en los medios de comunicación social de la Argentina. No encabeza secciones permanentes en los diarios de circulación nacional, donde es considerada parte de la información general. Y aparece como sección estable en muy pocos diarios provinciales. Surge episódicamente en la TV abierta o por cable, y en la radio, cuando hay catástrofes naturales (sequías o inundaciones), accidentes industriales y conflictos políticos o sectoriales r...

  10. Noise suppression in duct

    International Nuclear Information System (INIS)

    Ahmed, A.; Barfeh, M.A.G.

    2001-01-01

    In air-conditioning system the noise generated by supply fan is carried by conditioned air through the ductwork. The noise created in ductwork run may be transmission, regenerative and ductborne. Transmission noise is fan noise, regenerative noise is due to turbulence in flow and ductborne noise is the noise radiating from duct to surroundings. Some noise is attenuated in ducts also but if noise level is high then it needs to be attenuated. A simple mitre bend can attenuate-noise. This principle is extended to V and M-shape ducts with inside lining of fibreglass, which gave maximum attenuation of 77 dB and 62 dB respectively corresponding to 8 kHz frequency as compared to mitre, bend giving maximum 18 dB attenuation. Sound level meter measured sound levels with octave band filter and tests were conducted in anechoic room. A V-shape attenuator can be used at fan outlet and high frequency noise can be minimized greatly. (author)

  11. 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.

  12. Active3 noise reduction

    International Nuclear Information System (INIS)

    Holzfuss, J.

    1996-01-01

    Noise reduction is a problem being encountered in a variety of applications, such as environmental noise cancellation, signal recovery and separation. Passive noise reduction is done with the help of absorbers. Active noise reduction includes the transmission of phase inverted signals for the cancellation. This paper is about a threefold active approach to noise reduction. It includes the separation of a combined source, which consists of both a noise and a signal part. With the help of interaction with the source by scanning it and recording its response, modeling as a nonlinear dynamical system is achieved. The analysis includes phase space analysis and global radial basis functions as tools for the prediction used in a subsequent cancellation procedure. Examples are given which include noise reduction of speech. copyright 1996 American Institute of Physics

  13. Active noise cancellation algorithms for impulsive noise.

    Science.gov (United States)

    Li, Peng; Yu, Xun

    2013-04-01

    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 the results are presented and analyzed. The results show that the FXLMM and modified FXLMM algorithms are more robust in suppressing the adverse effect of sudden large amplitude impulses than FXLMS algorithm, and in particular, the proposed modified FXLMM algorithm can achieve better stability without sacrificing the performance of residual noise when encountering impulses.

  14. Dioxinas y medio ambiente

    Directory of Open Access Journals (Sweden)

    María Teresa Frejo Moya

    2011-12-01

    Full Text Available Con el término genérico dioxinas se designa al grupo de las dibenzo-p-dioxinas policloradas (PCDD y de los dibenzofuranos policlorados (PCDF, representantes típicos de los compuestos orgánicos persistentes (COPs. Se obtienen como productos secundarios no deseados de diversos procesos industriales en los que se emplea cloro en alguna de sus etapas. Las dioxinas han centrado en la última década una parte importante de la investigación médica en salud ambiental debido a su notable toxicidad, ya que son las sustancias químicas peligrosas más potentes creadas por el hombre, afectando al sistema nervioso e inmunitario, estando implicadas en la aparición de distintos tipos de cáncer y provocando la aparición de alteraciones hormonales, clasificándose actualmente como disruptores endocrinos. Por otra parte, su persistencia en el medio ambiente, resistencia a la degradación, bioacumulación y capacidad de transporte atmosférico entre las diversas fases medioambientales hace que sean considerados actualmente como compuestos peligrosos para el ser humano.

  15. 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.

  16. Impact of noise and air pollution on pregnancy outcomes.

    Science.gov (United States)

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

    2014-05-01

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

  17. Tritium monitoring system for near ambient measurements

    International Nuclear Information System (INIS)

    Falter, K.G.; Bauer, M.L.

    1992-01-01

    This paper describes the current status of research on an improved tritium measurement system at the Oak Ridge National Laboratory (ORNL) for the U.S. Navy. Present tritium-in-air monitoring systems installed by the Navy can reliably measure to less than 10 μCi/m 3 , but medical and safety issues are pushing measurement needs to below 1 μCi/m 3 , which is equivalent to 1-10 nCi/ml in liquid samples, using calcium metal converter. A significant effort has been expended over the past 10 years by the Navy RADIAC Development Program at ORNL on various schemes to improve the detection of tritium in both air and liquid at near ambient levels. One such scheme includes a liquid flow-through system based on an NE102 sponge scintillator with dual photomultiplier tubes for tube noise rejection

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

    Science.gov (United States)

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

    2017-09-15

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

  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. 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.

  1. Ambient Volatility of Triethyl Phosphate

    Science.gov (United States)

    2017-08-01

    AMBIENT VOLATILITY OF TRIETHYL PHOSPHATE ECBC-TR-1476 James H. Buchanan John J. Mahle RESEARCH AND...2017 2. REPORT TYPE Final 3. DATES COVERED (From - To) Oct 2016 – Jan 2017 4. TITLE: Ambient Volatility of Triethyl Phosphate 5a. CONTRACT...humidity on TEPO volatility is nearly as predicted by Raoult’s law, that is, vapor pressure suppression is proportional to ambient relative humidity. An

  2. Viewpoint-based ambient occlusion.

    Science.gov (United States)

    González, Francisco; Sbert, Mateu; Feixas, Miquel

    2008-01-01

    A new ambient occlusion technique builds a channel between various viewpoints and an object's polygons, providing the information needed to create an occlusion map with multiple application possibilities.

  3. Adaptive noise cancellation

    International Nuclear Information System (INIS)

    Akram, N.

    1999-01-01

    In this report we describe the concept of adaptive noise canceling, an alternative method of estimating signals corrupted by additive noise of interference. The method uses 'primary' input containing the corrupted signal and a 'reference' input containing noise correlated in some unknown way with the primary noise, the reference input is adaptively filtered and subtracted from the primary input to obtain the signal estimate. Adaptive filtering before subtraction allows the treatment of inputs that are deterministic or stochastic, stationary or time variable. When the reference input is free of signal and certain other conditions are met then noise in the primary input can be essentially eliminated without signal distortion. It is further shown that the adaptive filter also acts as notch filter. Simulated results illustrate the usefulness of the adaptive noise canceling technique. (author)

  4. 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...

  5. 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...... using running Danish and non-semantic speech materials as stimuli and modulated speech-spectrum and multi-talker babble noises as competing stimuli....

  6. Road traffic noise: annoyance, sleep disturbance, and public health implications.

    Science.gov (United States)

    Kim, Minho; Chang, Seo I; Seong, Jeong C; Holt, James B; Park, Tae H; Ko, Joon H; Croft, Janet B

    2012-10-01

    The WHO has recognized environmental noise as harmful pollution that causes adverse psychosocial and physiologic effects (i.e., annoyance and sleep disturbance) on human health. In Europe, noise-related health studies have been actively conducted, but the U.S. has lagged behind in this research field. This research predicted ambient levels of road traffic noise for a highly urbanized area: Fulton County GA. Assessment was made of noise impacts on the population, focusing on annoyance and sleep disturbance. All the data sets were collected during 2009-2011, and data analysis was performed in 2010-2011. The study used a sound-propagation model for noise-level prediction and derived noise-impact indicators for annoyance and sleep disturbance from exposure-response models. Then, annoyed and sleep-disturbed populations were predicted with the use of each noise-impact indicator. It was predicted that 109,967 people would be at risk of being highly annoyed, with 19,621 people at risk for high sleep disturbance for Fulton County GA. Noise-impact indicators such as the percentage of those who were highly annoyed and who had high levels of sleep disturbance were expected to be valuable metrics to compare noise equity among urban communities. Many residents of the greater Atlanta area may be exposed to noise levels that put them at risk of being highly annoyed or having high levels of sleep disturbance. These results, if generalized to other urban areas with high levels of road traffic, indicate that it may be important for the public's health to update existing noise-related policies or develop new ones to control and abate noise concerns in urban communities. Published by Elsevier Inc.

  7. 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.

  8. Noise in biological circuits.

    Science.gov (United States)

    Simpson, Michael L; Cox, Chris D; Allen, Michael S; McCollum, James M; Dar, Roy D; Karig, David K; Cooke, John F

    2009-01-01

    Noise biology focuses on the sources, processing, and biological consequences of the inherent stochastic fluctuations in molecular transitions or interactions that control cellular behavior. These fluctuations are especially pronounced in small systems where the magnitudes of the fluctuations approach or exceed the mean value of the molecular population. Noise biology is an essential component of nanomedicine where the communication of information is across a boundary that separates small synthetic and biological systems that are bound by their size to reside in environments of large fluctuations. Here we review the fundamentals of the computational, analytical, and experimental approaches to noise biology. We review results that show that the competition between the benefits of low noise and those of low population has resulted in the evolution of genetic system architectures that produce an uneven distribution of stochasticity across the molecular components of cells and, in some cases, use noise to drive biological function. We review the exact and approximate approaches to gene circuit noise analysis and simulation, and review many of the key experimental results obtained using flow cytometry and time-lapse fluorescent microscopy. In addition, we consider the probative value of noise with a discussion of using measured noise properties to elucidate the structure and function of the underlying gene circuit. We conclude with a discussion of the frontiers of and significant future challenges for noise biology. (c) 2009 John Wiley & Sons, Inc.

  9. 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...

  10. 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…

  11. 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.

  12. 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...

  13. 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 fir...... are semantically sound, and we demonstrate that each process admits a least analysis....

  14. 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?

  15. Underwater Noise from a Wave Energy Converter is unlikely to Affect Marine Mammals

    DEFF Research Database (Denmark)

    Tougaard, Jakob

    2015-01-01

    (Leq) in third-octave bands during operation of the converter were 106–109 dB re. 1 μPa in the range 125–250 Hz, 1–2 dB above ambient noise levels (statistically significant). Outside the range 125–250 Hz the noise from the converter was undetectable above the ambient noise. During start and stop...... were so low that they would barely be audible to marine mammals and the likelihood of negative impact from the noise appears minimal. A likely explanation for the low noise emissions is the construction of the converter where all moving parts, except for the absorbers themselves, are placed above water...

  16. Noise in miniature microphones.

    Science.gov (United States)

    Thompson, Stephen C; LoPresti, Janice L; Ring, Eugene M; Nepomuceno, Henry G; Beard, John J; Ballad, William J; Carlson, Elmer V

    2002-02-01

    The internal noise spectrum in miniature electret microphones of the type used in the manufacture of hearing aids is measured. An analogous circuit model of the microphone is empirically fit to the measured data and used to determine the important sources of noise within the microphone. The dominant noise source is found to depend on the frequency. Below 40 Hz and above 9 kHz, the dominant source is electrical noise from the amplifier circuit needed to buffer the electrical signal from the microphone diaphragm. Between approximately 40 Hz and 1 kHz, the dominant source is thermal noise originating in the acoustic flow resistance of the small hole pierced in the diaphragm to equalize barometric pressure. Between approximately 1 kHz and 9 kHz, the noise originates in the acoustic flow resistances of sound entering the microphone and propagating to the diaphragm. To further reduce the microphone internal noise in the audio band requires attacking these sources. A prototype microphone having reduced acoustical noise is measured and discussed.

  17. Effects of traffic noise

    Energy Technology Data Exchange (ETDEWEB)

    Gottlob, D.

    1986-02-01

    One of the main sources of noise is road traffic. In 1984 there were over 25 million cars, 1.2 million lorries, 1.3 million motor cycles and 1.6 million mopeds using our roads. Opinion polls showed that 21% of the population felt that they were affected by traffic noise as a nuisance factor. An outline of the effects of this noise on the affected population is given, illustrated by diagrams. Details about noise emissions (drive-past level) of the different types of vehicles in city traffic are stated and the effects of noise described. The author goes into the nuisance effect (noise is not a physical factor, but a psychosocial one), changes in behaviour (ways of speaking, reduction of stress on households in proportion to rising income and higher educational levels) and the consequences for health (the reaction of the body to noise is primarily a consequence of the psychosomatic organisation of ow bodies). In conclusion, the author deals with the subjective efficiency of noise protection measures. (HWJ).

  18. 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...

  19. 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...

  20. Noise from wind turbines

    International Nuclear Information System (INIS)

    Andersen, B.; Jakobsen, J.

    1992-11-01

    Based on a previous project concerning the calculation of the amount of noise emanating from wind turbine arrays, this one examines the subject further by investigating whether there could be significant differences in the amount of noise made by individual wind turbines in an array, and whether the noise is transmitted in varying directions - so that when it is carried in the same direction as the wind blows it would appear to be louder. The aim was also to determine whether the previously used method of calculation lacked precision. It was found that differences in noise niveaux related to individual wind turbines were insignificant and that noise was not so loud when it was not borne in the direction of the wind. It was necessary to change the method of calculation as reckoning should include the influence of the terrain, wind velocity and distance. The measuring and calculation methods are exemplified and the resulting measurements are presented in detail. (AB)

  1. Noise from wind turbines

    International Nuclear Information System (INIS)

    Andersen, B.; Larsen, P.

    1993-01-01

    Denmark has 3200 wind turbines with an installed maximum capacity of 418MW. The most important Danish research projects into wind turbine noise and the main results are listed. These date from 1983. Two comprehensive studies are currently in progress. The first is an analytical and empirical investigation of aerodynamic noise from wind turbine rotors and has so far dealt mainly with tip noise. The measurement method, using a hard board mounted microphone on the ground near the turbine, is described. Four different tip designs have been tested. Some examples of reference sound power level spectra for three of the designs are presented. During the past two years a computerbased data acquisition system has been used for real-time determination of sound power levels. The second study, which has just commenced, is on annoyance from wind turbine noise. It will include noise measurements, masking calculations and a social survey on the perceived nuisance. (UK)

  2. [Urban noise pollution].

    Science.gov (United States)

    Chouard, C H

    2001-07-01

    Noise is responsible for cochlear and general damages. Hearing loss and tinnitus greatly depend on sound intensity and duration. Short-duration sound of sufficient intensity (gunshot or explosion) will not be described because they are not currently encountered in our normal urban environment. Sound levels of less than 75 d (A) are unlikely to cause permanent hearing loss, while sound levels of about 85 d (A) with exposures of 8 h per day will produce permanent hearing loss after many years. Popular and largely amplified music is today one of the most dangerous causes of noise induced hearing loss. The intensity of noises (airport, highway) responsible for stress and general consequences (cardiovascular) is generally lower. Individual noise sensibility depends on several factors. Strategies to prevent damage from sound exposure should include the use of individual hearing protection devices, education programs beginning with school-age children, consumer guidance, increased product noise labelling, and hearing conservation programs for occupational settings.

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

    Science.gov (United States)

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

    2017-01-01

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

  4. Analytical Methods for Energy Diversity and Security. Portfolio Optimization in the Energy Sector: A Tribute to the work of Dr. Shimon Awerbuch. Chapter 7. The role of wind generation in enhancing Scotland's energy diversity and security

    International Nuclear Information System (INIS)

    Jansen, J.C.; Beurskens, L.W.M.

    2008-11-01

    This volume aims at professionals in academia, industry and government interested in the rapidly evolving area at the nexus between energy and climate change policy. The cutting-edge international contributions allow for a wide coverage of the topic. Energy Diversity and Security focuses on the consideration of financial risk in the energy sector. It describes how tools borrowed from financial economic theory, in particular mean-variance portfolio theory, can provide insights on the costs and benefits of diversity, and thus inform investment decision making in conditions of uncertainty. It gives the reader an in-depth understanding of how to manage risk at a time when the world's focus is on this area. The book provides insights from leading authorities in the area of energy security. It gives readers abundant, rigorous analysis and guidance at a critical time in facing the twin challenges of energy security and climate change. The book also highlights the role of clean energy technology in moving towards future diverse and intelligent electricity systems. In this chapter attention is paid to the role of wind generation in enhancing Scotland's energy diversity and security

  5. Cryogenic ultra-low-noise SiGe transistor amplifier.

    Science.gov (United States)

    Ivanov, B I; Trgala, M; Grajcar, M; Il'ichev, E; Meyer, H-G

    2011-10-01

    An ultra-low-noise one-stage SiGe heterojunction bipolar transistor amplifier was designed for cryogenic temperatures and a frequency range of 10 kHz-100 MHz. A noise temperature T(N) ≈ 1.4 K was measured at an ambient temperature of 4.2 K at frequencies between 100 kHz and 100 MHz for a source resistance of ~50 Ω. The voltage gain of the amplifier was 25 dB at a power consumption of 720 μW. The input voltage noise spectral density of the amplifier is about 35 pV/√Hz. The low noise resistance and power consumption makes the amplifier suitable for readout of resistively shunted DC SQUID magnetometers and amplifiers.

  6. Effects of noise frequency on performance and annoyance. M.S. Thesis - Georgia Inst. of Tech.

    Science.gov (United States)

    Key, K. F.

    1979-01-01

    Using a complex psychomotor task performed for 50 minutes in the presence of low frequency noise, high frequency noise, or ambient noise, annoyance ratings were obtained for noises of various frequencies by the method of magnitude estimation. The results suggest that high frequency noise affects female performance to a greater extent than male performance. Contrasted to these performance effects, the sexes did not differ in their annoyance ratings. A monotonically increasing relationship between annoyance and noise frequency was found (except for a decrease in annoyance at 8,000 Hz). It is concluded that both performance and annoyance responses may need to be assessed in certain situations to adequately describe human reaction to noise.

  7. Work zone noise levels at Aarti steel plant, Orissa and its attenuation in far field.

    Science.gov (United States)

    Kerketta, S; Dash, P K; Narayan, L T P

    2009-09-01

    The outdoor noise levels from the various work places of the integrated steel plant were measured. The average noise level (L(eqst)) at the outdoor was found between 59-84 dBA. The combined noise level (L(eq)) of the plant was 90 dBA and 92 dBA on 1.12.2006 and 1612.2006, respectively. The noise levels in the far fields were found between 43-70 dBA for daytime and meet the noise quality for industrial (75 dBA) area and residential (55 dBA) areas. Maximum attenuation of 47-49 dBA of noise level was found at worker's colony and may be attributed mainly to the ground absorption. As the air quality standards of the area in respect of noise in the ambient is tending to increase, engineering control measures suggested to the noisiest equipments for better economically viable and higher payback period.

  8. Effects of background noise on total noise annoyance

    Science.gov (United States)

    Willshire, K. F.

    1987-01-01

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

  9. Salud ambiental: conceptos y actividades

    Directory of Open Access Journals (Sweden)

    Ordóñez Gonzalo A.

    2000-01-01

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

  10. Salud ambiental: conceptos y actividades

    Directory of Open Access Journals (Sweden)

    Gonzalo A. Ordóñez

    2000-03-01

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

  11. Towards equitable solutions to siting and noise problems in windfarms

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  12. Noise and Hearing Loss Prevention

    Science.gov (United States)

    ... message, please visit this page: About CDC.gov . NOISE AND HEARING LOSS PREVENTION Language: English (US) Español ( ... when hazardous noise levels cannot be adequately reduced. Noise and Hearing Loss on the NIOSH Science Blog ...

  13. Publicidade e ambiente: alguns contornos

    OpenAIRE

    Almeida Jr.,Antonio Ribeiro de; Andrade,Thales Novaes de

    2007-01-01

    O presente artigo trata da importância da publicidade na construção social do debate ambiental. Os estudos sobre mídia e ambiente geralmente focam o conteúdo de jornais e programas televisivos, mas nas últimas décadas a publicidade passou a chamar a atenção dos estudiosos sobre o tema. O trabalho procurou discutir a importância do fenômeno do consumo no mundo moderno, e os efeitos sentidos na área ambiental. A seguir são discutidos alguns aspectos do aprimoramento do discurso publicitário no ...

  14. Handbook Of Noise And Vibration

    International Nuclear Information System (INIS)

    1995-12-01

    This book is about noise and vibration. The first chapter has explanations of noise such as basic of sound, influence of noise, assessment of noise, measurement of prevention of noise and technology, case of noise measurement and soundproof. The second chapter describes vibration with outline, theory of vibration, interpretation of vibration, measurement for reduction of vibration, case of design of protection against vibration. It deals with related regulation and method of measurement.

  15. Ambient Monitoring Technology Information Center (AMTIC)

    Science.gov (United States)

    This site contains information on ambient air quality monitoring programs, monitoring methods, quality assurance and control procedures, and federal regulations related to ambient air quality monitoring.

  16. 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.

  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. Fluctuations of offshore wind generation: Statistical modelling

    DEFF Research Database (Denmark)

    Pinson, Pierre; Christensen, Lasse E.A.; Madsen, Henrik

    2007-01-01

    The magnitude of power fluctuations at large offshore wind farms has a significant impact on the control and management strategies of their power output. If focusing on the minute scale, one observes successive periods with smaller and larger power fluctuations. It seems that different regimes yi...

  19. Global potential for wind-generated electricity.

    Science.gov (United States)

    Lu, Xi; McElroy, Michael B; Kiviluoma, Juha

    2009-07-07

    The potential of wind power as a global source of electricity is assessed by using winds derived through assimilation of data from a variety of meteorological sources. The analysis indicates that a network of land-based 2.5-megawatt (MW) turbines restricted to nonforested, ice-free, nonurban areas operating at as little as 20% of their rated capacity could supply >40 times current worldwide consumption of electricity, >5 times total global use of energy in all forms. Resources in the contiguous United States, specifically in the central plain states, could accommodate as much as 16 times total current demand for electricity in the United States. Estimates are given also for quantities of electricity that could be obtained by using a network of 3.6-MW turbines deployed in ocean waters with depths <200 m within 50 nautical miles (92.6 km) of closest coastlines.

  20. Wind Generation on Winnebago Tribal Lands

    Energy Technology Data Exchange (ETDEWEB)

    Multiple

    2009-09-30

    The Winnebago Wind Energy Study evaluated facility-scale, community-scale and commercial-scale wind development on Winnebago Tribal lands in northeastern Nebraska. The Winnebago Tribe of Nebraska has been pursuing wind development in various forms for nearly ten years. Wind monitoring utilizing loaned met towers from NREL took place during two different periods. From April 2001 to April 2002, a 20-meter met tower monitored wind data at the WinnaVegas Casino on the far eastern edge of the Winnebago reservation in Iowa. In late 2006, a 50-meter tower was installed, and subsequently monitored wind data at the WinnaVegas site from late 2006 through late 2008. Significant challenges with the NREL wind monitoring equipment limited the availability of valid data, but based on the available data, average wind speeds between 13.6 – 14.3 miles were indicated, reflecting a 2+/3- wind class. Based on the anticipated cost of energy produced by a WinnaVegas wind turbine, and the utility policies and rates in place at this time, a WinnaVegas wind project did not appear to make economic sense. However, if substantial grant funding were available for energy equipment at the casino site, and if either Woodbury REC backup rates were lower, or NIPCO was willing to pay more for wind power, a WinnaVegas wind project could be feasible. With funding remaining in the DOE-funded project budget,a number of other possible wind project locations on the Winnebago reservation were considered. in early 2009, a NPPD-owned met tower was installed at a site identified in the study pursuant to a verbal agreement with NPPD which provided for power from any ultimately developed project on the Western Winnebago site to be sold to NPPD. Results from the first seven months of wind monitoring at the Western Winnebago site were as expected at just over 7 meters per second at 50-meter tower height, reflecting Class 4 wind speeds, adequate for commercial development. If wind data collected in the remaining months of the twelve-month collection period is consistent with that collected in the first seven months, the Western Winnebago site may present an interesting opportunity for Winnebago. Given the distance to nearby substations, and high cost of interconnection at higher voltage transmission lines, Winnebago would likely need to be part of a larger project in order to reduce power costs to more attractive levels. Another alternative would be to pursue grant funding for a portion of development or equipment costs, which would also help reduce the cost of power produced. The NREL tower from the WinnaVegas site was taken down in late 2008, re-instrumented and installation attempted on the Thunderway site south of the Winnebago community. Based on projected wind speeds, current equipment costs, and the project’s proximity to substations for possible interconnection, a Thunderway community-scale wind project could also be feasible.

  1. Comunicadores para la informaclon ambiental

    Directory of Open Access Journals (Sweden)

    Luz Marina Cabrera Morillo

    2013-07-01

    Full Text Available La Red Colombiana de Formación Ambiental en convenio con la Corporación Autónoma de los Valles del Sinú y del San Jorge y con el apoyo del Politécnico Grancolombiano, desarrolló un diplomado en Periodismo Ambiental en la ciudad de Montería, Departamento de Córdoba. La experiencia que ha contribuido a fortalecer la construcción de la cultura ambiental en la región; le ha permitido mayor visibilidad a los proyectos de la Corporación y facilitado la participación ciudadana. Este documento presenta el contexto de la formación de los comunicadores para la información ambiental, las características del diplomado y establece algunos de los logros alcanzados.

  2. Acoustics Noise Test Cell

    Data.gov (United States)

    Federal Laboratory Consortium — The Acoustic Noise Test Cell at the NASA/Caltech Jet Propulsion Laboratory (JPL) is located adjacent to the large vibration system; both are located in a class 10K...

  3. Alien Noise Cancellation

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Full FEXT Cancellation. Expectation Maximization based Algorithms. Partial Cancellation. Optimal Choice of what to Cancel and what not to! Alien Noise Cancellation. Efficient Crosstalk channel estimation. In addition:

  4. Airframe noise prediction evaluation

    Science.gov (United States)

    Yamamoto, Kingo J.; Donelson, Michael J.; Huang, Shumei C.; Joshi, Mahendra C.

    1995-01-01

    The objective of this study is to evaluate the accuracy and adequacy of current airframe noise prediction methods using available airframe noise measurements from tests of a narrow body transport (DC-9) and a wide body transport (DC-10) in addition to scale model test data. General features of the airframe noise from these aircraft and models are outlined. The results of the assessment of two airframe prediction methods, Fink's and Munson's methods, against flight test data of these aircraft and scale model wind tunnel test data are presented. These methods were extensively evaluated against measured data from several configurations including clean, slat deployed, landing gear-deployed, flap deployed, and landing configurations of both DC-9 and DC-10. They were also assessed against a limited number of configurations of scale models. The evaluation was conducted in terms of overall sound pressure level (OASPL), tone corrected perceived noise level (PNLT), and one-third-octave band sound pressure level (SPL).

  5. Approximations to camera sensor noise

    Science.gov (United States)

    Jin, Xiaodan; Hirakawa, Keigo

    2013-02-01

    Noise is present in all image sensor data. Poisson distribution is said to model the stochastic nature of the photon arrival process, while it is common to approximate readout/thermal noise by additive white Gaussian noise (AWGN). Other sources of signal-dependent noise such as Fano and quantization also contribute to the overall noise profile. Question remains, however, about how best to model the combined sensor noise. Though additive Gaussian noise with signal-dependent noise variance (SD-AWGN) and Poisson corruption are two widely used models to approximate the actual sensor noise distribution, the justification given to these types of models are based on limited evidence. The goal of this paper is to provide a more comprehensive characterization of random noise. We concluded by presenting concrete evidence that Poisson model is a better approximation to real camera model than SD-AWGN. We suggest further modification to Poisson that may improve the noise model.

  6. Expected Seismicity and the Seismic Noise Environment of Europa

    Science.gov (United States)

    Panning, Mark P.; Stähler, Simon C.; Huang, Hsin-Hua; Vance, Steven D.; Kedar, Sharon; Tsai, Victor C.; Pike, William T.; Lorenz, Ralph D.

    2018-01-01

    Seismic data will be a vital geophysical constraint on internal structure of Europa if we land instruments on the surface. Quantifying expected seismic activity on Europa both in terms of large, recognizable signals and ambient background noise is important for understanding dynamics of the moon, as well as interpretation of potential future data. Seismic energy sources will likely include cracking in the ice shell and turbulent motion in the oceans. We define a range of models of seismic activity in Europa's ice shell by assuming each model follows a Gutenberg-Richter relationship with varying parameters. A range of cumulative seismic moment release between 1016 and 1018 Nm/yr is defined by scaling tidal dissipation energy to tectonic events on the Earth's moon. Random catalogs are generated and used to create synthetic continuous noise records through numerical wave propagation in thermodynamically self-consistent models of the interior structure of Europa. Spectral characteristics of the noise are calculated by determining probabilistic power spectral densities of the synthetic records. While the range of seismicity models predicts noise levels that vary by 80 dB, we show that most noise estimates are below the self-noise floor of high-frequency geophones but may be recorded by more sensitive instruments. The largest expected signals exceed background noise by ˜50 dB. Noise records may allow for constraints on interior structure through autocorrelation. Models of seismic noise generated by pressure variations at the base of the ice shell due to turbulent motions in the subsurface ocean may also generate observable seismic noise.

  7. Emergency department noise: mental activation or mental stress?

    Science.gov (United States)

    Folscher, Lindy-Lee; Goldstein, Lara Nicole; Wells, Mike; Rees, David

    2015-06-01

    Healthcare professionals working in emergency medicine are often exposed to noisy environments. We determined if there is any difference in cognitive task performance required for clinical decision-making of healthcare professionals in a quiet compared with noisy environment and to assess the subjective experience of participants with regard to performance in a noisy environment. This was a prospective cross-over study conducted at three academic hospitals in Johannesburg, South Africa. 41 doctors involved in the emergency management of patients were administered six matched and prevalidated medical questions over a 30-min period. Each doctor completed half of the questions with exposure to ambient noise (range 40-52 dB(A)) and the other half with exposure to pre-recorded background emergency department noise at 80-85 dB(A). The questions were completed in alternating quiet and noise: half of the physicians answered the odd questions in noise and half answered even numbered questions in noise. Each question was scored out of 10 and the time taken to complete each question was recorded. Overall median test scores in quiet and noise were 18.5/30 and 20/30 (p=0.2), respectively; time for test completion was longer in quiet (836 s in quiet and 819 s in noise (p=0.006)). While there was no statistically significant difference in task performance, 65% of the doctors found the noise distracting with 88% experiencing varying degrees of stress. Performance of mental tasks is maintained during noise exposure but noise exposure is associated with significant degrees of self-reported distress. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  8. Noise Abatement Materials

    Science.gov (United States)

    1986-01-01

    A former NASA employee who discovered a kind of plastic that soaked up energy, dampened vibrations, and was a good noise abatement material, founded a company to market noise deadening adhesives, sheets, panels and enclosures. Known as SMART products, they are 75-80% lighter than ordinary soundproofing material and have demonstrated a high degree of effectiveness. The company, Varian Associates, makes enclosures for high voltage terminals and other electronic system components, and easily transportable audiometric test booths.

  9. Evaluation of noise in a neonatal unit at a university hospital

    Directory of Open Access Journals (Sweden)

    Ariadne Pinheiro Nazario

    2015-05-01

    Full Text Available Objective: To identify and measure the main sources of noise, to determine the levels of ambient noise and to know the perception of employees about noise in a Neonatal Unit. Material and method: A quantitative study developed in a Neonatal Unit School Hospital, Paraná, Brazil, conducted in three steps: identification of the main sources of noise and subsequent measure; interview with the multidisciplinary team about the perception of noise in the unit; and dimensioning noise ambient for two non-consecutive weeks. Results: The main sources of noise were: monitor and equipment alarms, open water faucets, trash can lids, among others. The mean of the two weeks period was: Leq 44.4 dB, Lmax 104.5 dB, Lmin 40 dB and Lpeak 144.8 dB. Employees acknowledged that intense noise is prejudicial to them and to babies. Conclusion: It was found that the mean value of the noise is within the recommended, but with very high levels of Lpeak and Lmax.

  10. 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...

  11. Near-ambient solid polymer fuel cell

    Science.gov (United States)

    Holleck, G. L.

    1993-01-01

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

  12. Magnetic flux noise in copper oxide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, Mark Joseph [Univ. of California, Berkeley, CA (United States)

    1991-11-01

    Magnetic flux noise and flux creep in thin films and single crystals of YBa2Cu3O7-x, Bi2Sr2CaCu2O8+x, Tl2Ca2Ba2Cu3Ox, and TlCa2Ba2Cu3Ox 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 YBa2Cu3O7-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.

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

    Science.gov (United States)

    Weiss, C. J.

    2009-12-01

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

  14. A neural network for noise correlation classification

    Science.gov (United States)

    Paitz, Patrick; Gokhberg, Alexey; Fichtner, Andreas

    2018-02-01

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

  15. Noise sensitivity and sleep disturbance

    NARCIS (Netherlands)

    Laszlo, H.E.; Janssen, S.A.; Babisch, W.; Hansell, A.L.

    2012-01-01

    It has been shown that noise induced health effects are strongly related to non-acoustical factors such as noise sensitivity. It is a stable personality trait and it can be conceptualised as a causal pathway confounder and/or effect modifier between noise and health. Furthermore noise sensitivity

  16. 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...... and categorized as follows: noise levels, noise sources, staff performances, and patient’s perception of noise. Each study was assessed according to the strength of the evidence and the quality of the study. Noise levels in the OR in general exceed recommended levels, and the noise sources are related...... 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....

  17. Resistive Switching Assisted by Noise

    OpenAIRE

    Patterson, G. A.; Fierens, P. I.; Grosz, D. F.

    2013-01-01

    We extend results by Stotland and Di Ventra on the phenomenon of resistive switching aided by noise. We further the analysis of the mechanism underlying the beneficial role of noise and study the EPIR (Electrical Pulse Induced Resistance) ratio dependence with noise power. In the case of internal noise we find an optimal range where the EPIR ratio is both maximized and independent of the preceding resistive state. However, when external noise is considered no beneficial effect is observed.

  18. Evaluation of the susceptibility to pitting corrosion of steel api 5L x42 exposed to solutions containing chloride ions and CO{sub 2} by electrochemical noise measurements; Evaluacion de la susceptibilidad a la corrosion por picado del acero api 5l x42 expuesto a un ambiente con cloruros y CO{sub 2} mediante la tecnica de ruido electroquimico

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Ballesteros, D.; Rodriguez-Vanegas, N.; Anteliz, C.; Sarmiento Klapper, H.

    2011-07-01

    The concentration of chloride ions and the partial pressure of CO{sub 2} play an important role in the degradation of low-carbon steels used for the construction of pipelines in oil and gas industry. In order to evaluate the susceptibility of carbon steel API 5L X42 to pitting corrosion electrochemical noise and linear polarization resistance measurements were carried out in aqueous solutions containing chloride ions and CO{sub 2}. The concentration of chloride ions was varied between, 10000 and 18000 ppm, and the CO{sub 2} partial pressure between 10 psi and 18 psi. Experimental results pointed out that the formation of protective layer, consisting mainly of FeCO{sub 3}, depends on the partial pressure of CO{sub 2} in the system. Nevertheless, the stability of this layer was considerably affected by increasing the concentration of chloride ions causing that localized corrosion has taken place in some areas of the surface of API 5L X42, which were detected by electrochemical noise technique. (Author) 10 refs.

  19. Engineering out the noise.

    Science.gov (United States)

    Yankaskas, Kurt; Fischer, Raymond; Spence, Jesse; Komrower, Jeffrey

    2017-06-01

    The US Navy, through an Office of Naval Research (ONR) lead effort on Noise Induced Hearing Loss (NIHL), is investigating methods and techniques to mitigate hearing loss for the crews and warfighters. Hearing protection is a viable and increasingly popular method of reducing hearing exposure for many ship crew members; however, it has limitations on comfort and low frequency effectiveness. Furthermore, Personal Hearing Protection (PHP) is often used improperly. Proper vessel planning, programmatic changes and advances in noise control engineering can also have significant impacts by inherently reducing noise exposure through ship design and use of noise control treatments. These impacts go beyond hearing loss mitigation since they can improve quality of life onboard vessels and provide enhanced warfighter performance. Such approaches also can be made to work in the lower frequency range where hearing protection is not as effective. This paper describes non-hearing protection methods being implemented to mitigate and control noise within the US Navy and US Marine Corps. These approaches reflect the latest changes to Mil-Std 1474E, Appendix F. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. 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.