WorldWideScience

Sample records for high background noise

  1. Background Noise Distribution before and afterHigh-Resolution Processing in Ship-borne Radar

    Institute of Scientific and Technical Information of China (English)

    ZHANGZhong

    2005-01-01

    When high-resolution algorithm is applied in ship-borne radar~ high-resolution algorithm's nonlinearity and distributional characteristics before highresolution processing determine background clutter's distributional characteristics after high-resolution and detector design afterwards. Because background noise before high-resolution has physical significance, the statistical model of first-order Bragg lines and second order components of sea clutter is put forward. Then by using higher-order cumulative quantity's statistical verification of actually measured data, it is concluded that background noise before high-resolution conforms to normal distribution in ship-borne radar. The non-linearity of high-resolution algorithm determines that background noise after high-resolution processing conforms to non-normal distribution. Non-normal distributed clutter mainly include Weibull, Lognormal and K clutter. Rayleigh clutter can be seen as special case of Weibull clutter. These clutter have differently statistical characteristics and can be discriminated by clutter characteristics recognition. The numerical domain's distribution after high-resolution processing is determined by improved minimum entropy clutter characteristics recognition method based on rule AIC, namely two-parameter domain scanning method. This identification method has higher recognition rate. It is verified that background noise after high-resolution by pre-whitenedMUSIC conforms to lognormal distribution.

  2. High background noise shapes selective auditory filters in a tropical cricket.

    Science.gov (United States)

    Schmidt, Arne K D; Riede, Klaus; Römer, Heiner

    2011-05-15

    Because of call frequency overlap and masking interference, the airborne sound channel represents a limited resource for communication in a species-rich cricket community like the tropical rainforest. Here we studied the frequency tuning of an auditory neuron mediating phonotaxis in the rainforest cricket Paroecanthus podagrosus, suffering from strong competition, in comparison with the same homologous neuron in two species of European field crickets, where such competition does not exist. As predicted, the rainforest species exhibited a more selective tuning compared with the European counterparts. The filter reduced background nocturnal noise levels by 26 dB, compared with only 16 and 10 dB in the two European species. We also quantified the performance of the sensory filter under the different filter regimes by examining the representation of the species-specific amplitude modulation of the male calling song, when embedded in background noise. Again, the filter of the rainforest cricket performed significantly better in terms of representing this important signal parameter. The neuronal representation of the calling song pattern within receivers was maintained for a wide range of signal-to-noise ratios because of the more sharply tuned sensory system and selective attention mechanisms. Finally, the rainforest cricket also showed an almost perfect match between the filter for sensitivity and the peripheral filter for directional hearing, in contrast to its European counterparts. We discuss the consequences of these adaptations for intraspecific acoustic communication and reproductive isolation between species.

  3. BACKGROUND NOISE LEVELS IN STUDIOS AND AUDITORIA

    OpenAIRE

    James, A.

    1990-01-01

    The specification of background noise levels for auditoria must strike a balance between the lowest possible noise level from services and the need for some "masking" of extraneous sources. Studios are often designed to provide a suitable level of masking, using either aerodynamic or electronically-generated white noise. Data on noise levels in a large number of auditoria have been examined to determine whether a similar process is applicable to these. A wide range of seemingly arbitrary desi...

  4. Urban background noise mapping: the general model

    NARCIS (Netherlands)

    Wei, W.; Botteldooren, D.; Renterghem, T. van; Hornikx, M.; Forssen, J.; Salomons, E.; Ogren, M.

    2014-01-01

    Surveys show that inhabitants of dwellings exposed to high noise levels benefit from having access to a quiet side. However, current practice in noise prediction often underestimates the noise levels at a shielded façade. Multiple reflections between façades in street canyons and inner yards are com

  5. Urban background noise mapping: the general model

    NARCIS (Netherlands)

    Wei, W.; Botteldooren, D.; Renterghem, T. van; Hornikx, M.; Forssen, J.; Salomons, E.; Ogren, M.

    2014-01-01

    Surveys show that inhabitants of dwellings exposed to high noise levels benefit from having access to a quiet side. However, current practice in noise prediction often underestimates the noise levels at a shielded façade. Multiple reflections between façades in street canyons and inner yards are com

  6. A method of background noise cancellation for SQUID applications

    Energy Technology Data Exchange (ETDEWEB)

    He, D F [Iwate Industrial Promotion Center, Morioka 020-0045 (Japan); Yoshizawa, M [Faculty of Engineering, Iwate University, Morioka 020-8551 (Japan)

    2003-12-01

    When superconducting quantum inference devices (SQUIDs) operate in low-cost shielding or unshielded environments, the environmental background noise should be reduced to increase the signal-to-noise ratio. In this paper we present a background noise cancellation method based on a spectral subtraction algorithm. We first measure the background noise and estimate the noise spectrum using fast Fourier transform (FFT), then we subtract the spectrum of background noise from that of the observed noisy signal and the signal can be reconstructed by inverse FFT of the subtracted spectrum. With this method, the background noise, especially stationary inferences, can be suppressed well and the signal-to-noise ratio can be increased. Using high-T{sub C} radio-frequency SQUID gradiometer and magnetometer, we have measured the magnetic field produced by a watch, which was placed 35 cm under a SQUID. After noise cancellation, the signal-to-noise ratio could be greatly increased. We also used this method to eliminate the vibration noise of a cryocooler SQUID.

  7. Speech recognition in natural background noise.

    Directory of Open Access Journals (Sweden)

    Julien Meyer

    Full Text Available In the real world, human speech recognition nearly always involves listening in background noise. The impact of such noise on speech signals and on intelligibility performance increases with the separation of the listener from the speaker. The present behavioral experiment provides an overview of the effects of such acoustic disturbances on speech perception in conditions approaching ecologically valid contexts. We analysed the intelligibility loss in spoken word lists with increasing listener-to-speaker distance in a typical low-level natural background noise. The noise was combined with the simple spherical amplitude attenuation due to distance, basically changing the signal-to-noise ratio (SNR. Therefore, our study draws attention to some of the most basic environmental constraints that have pervaded spoken communication throughout human history. We evaluated the ability of native French participants to recognize French monosyllabic words (spoken at 65.3 dB(A, reference at 1 meter at distances between 11 to 33 meters, which corresponded to the SNRs most revealing of the progressive effect of the selected natural noise (-8.8 dB to -18.4 dB. Our results showed that in such conditions, identity of vowels is mostly preserved, with the striking peculiarity of the absence of confusion in vowels. The results also confirmed the functional role of consonants during lexical identification. The extensive analysis of recognition scores, confusion patterns and associated acoustic cues revealed that sonorant, sibilant and burst properties were the most important parameters influencing phoneme recognition. . Altogether these analyses allowed us to extract a resistance scale from consonant recognition scores. We also identified specific perceptual consonant confusion groups depending of the place in the words (onset vs. coda. Finally our data suggested that listeners may access some acoustic cues of the CV transition, opening interesting perspectives for

  8. Background noise spectra of global seismic stations

    Energy Technology Data Exchange (ETDEWEB)

    Wada, M.M.; Claassen, J.P.

    1996-08-01

    Over an extended period of time station noise spectra were collected from various sources for use in estimating the detection and location performance of global networks of seismic stations. As the database of noise spectra enlarged and duplicate entries became available, an effort was mounted to more carefully select station noise spectra while discarding others. This report discusses the methodology and criteria by which the noise spectra were selected. It also identifies and illustrates the station noise spectra which survived the selection process and which currently contribute to the modeling efforts. The resulting catalog of noise statistics not only benefits those who model network performance but also those who wish to select stations on the basis of their noise level as may occur in designing networks or in selecting seismological data for analysis on the basis of station noise level. In view of the various ways by which station noise were estimated by the different contributors, it is advisable that future efforts which predict network performance have available station noise data and spectral estimation methods which are compatible with the statistics underlying seismic noise. This appropriately requires (1) averaging noise over seasonal and/or diurnal cycles, (2) averaging noise over time intervals comparable to those employed by actual detectors, and (3) using logarithmic measures of the noise.

  9. Measurement of Acceptable Noise Level with Background Music.

    Science.gov (United States)

    Ahn, Hyun-Jung; Bahng, Junghwa; Lee, Jae Hee

    2015-09-01

    Acceptable noise level (ANL) is a measure of the maximum background noise level (BNL) that a person is willing to tolerate while following a target story. Although researchers have used various sources of target sound in ANL measures, a limited type of background noise has been used. Extending the previous study of Gordon-Hickey & Moore (2007), the current study determined the effect of music genre and tempo on ANLs as possible factors affecting ANLs. We also investigated the relationships between individual ANLs and the familiarity of music samples and between music ANLs and subjective preference. Forty-one participants were seperated into two groups according to their ANLs, 29 low-ANL listeners and 12 high-ANL listeners. Using Korean ANL material, the individual ANLs were measured based on the listeners' most comfortable listening level and BNL. The ANLs were measured in six conditions, with different music tempo (fast, slow) and genre (K-pop, pop, classical) in a counterbalanced order. Overall, ANLs did not differ by the tempo of background music, but music genre significantly affected individual ANLs. We observed relatively higher ANLs with K-pop music and relatively lower ANLs with classical music. This tendency was similar in both low-ANL and high-ANL groups. However, the subjective ratings of music familiarity and preference affected ANLs differently for low-ANL and high-ANL groups. In contrast to the low-ANL listeners, the ANLs of the high-ANL listeners were significantly affected by music familiarity and preference. The genre of background music affected ANLs obtained using background music. The degree of music familiarity and preference appears to be associated with individual susceptibility to background music only for listeners who are greatly annoyed by background noise (high-ANL listeners).

  10. Interdependent processing and encoding of speech and concurrent background noise.

    Science.gov (United States)

    Cooper, Angela; Brouwer, Susanne; Bradlow, Ann R

    2015-05-01

    Speech processing can often take place in adverse listening conditions that involve the mixing of speech and background noise. In this study, we investigated processing dependencies between background noise and indexical speech features, using a speeded classification paradigm (Garner, 1974; Exp. 1), and whether background noise is encoded and represented in memory for spoken words in a continuous recognition memory paradigm (Exp. 2). Whether or not the noise spectrally overlapped with the speech signal was also manipulated. The results of Experiment 1 indicated that background noise and indexical features of speech (gender, talker identity) cannot be completely segregated during processing, even when the two auditory streams are spectrally nonoverlapping. Perceptual interference was asymmetric, whereby irrelevant indexical feature variation in the speech signal slowed noise classification to a greater extent than irrelevant noise variation slowed speech classification. This asymmetry may stem from the fact that speech features have greater functional relevance to listeners, and are thus more difficult to selectively ignore than background noise. Experiment 2 revealed that a recognition cost for words embedded in different types of background noise on the first and second occurrences only emerged when the noise and the speech signal were spectrally overlapping. Together, these data suggest integral processing of speech and background noise, modulated by the level of processing and the spectral separation of the speech and noise.

  11. Countermeasure against blinding attacks on low-noise detectors with a background-noise-cancellation scheme

    Science.gov (United States)

    Lee, Min Soo; Park, Byung Kwon; Woo, Min Ki; Park, Chang Hoon; Kim, Yong-Su; Han, Sang-Wook; Moon, Sung

    2016-12-01

    We developed a countermeasure against blinding attacks on low-noise detectors with a background-noise-cancellation scheme in quantum key distribution (QKD) systems. Background-noise cancellation includes self-differencing and balanced avalanche photon diode (APD) schemes and is considered a promising solution for low-noise APDs, which are critical components in high-performance QKD systems. However, its vulnerability to blinding attacks has been recently reported. In this work, we propose a countermeasure that prevents this potential security loophole from being used in detector blinding attacks. An experimental QKD setup is implemented and various tests are conducted to verify the feasibility and performance of the proposed method. The obtained measurement results show that the proposed scheme successfully detects occurring blinding-attack-based hacking attempts.

  12. Measurement of Acceptable Noise Level with Background Music

    OpenAIRE

    Ahn, Hyun-Jung; Bahng, Junghwa; Lee, Jae Hee

    2015-01-01

    Background and Objectives Acceptable noise level (ANL) is a measure of the maximum background noise level (BNL) that a person is willing to tolerate while following a target story. Although researchers have used various sources of target sound in ANL measures, a limited type of background noise has been used. Extending the previous study of Gordon-Hickey & Moore (2007), the current study determined the effect of music genre and tempo on ANLs as possible factors affecting ANLs. We also investi...

  13. Auditory intensity processing: Effect of MRI background noise.

    Science.gov (United States)

    Angenstein, Nicole; Stadler, Jörg; Brechmann, André

    2016-03-01

    Studies on active auditory intensity discrimination in humans showed equivocal results regarding the lateralization of processing. Whereas experiments with a moderate background found evidence for right lateralized processing of intensity, functional magnetic resonance imaging (fMRI) studies with background scanner noise suggest more left lateralized processing. With the present fMRI study, we compared the task dependent lateralization of intensity processing between a conventional continuous echo planar imaging (EPI) sequence with a loud background scanner noise and a fast low-angle shot (FLASH) sequence with a soft background scanner noise. To determine the lateralization of the processing, we employed the contralateral noise procedure. Linearly frequency modulated (FM) tones were presented monaurally with and without contralateral noise. During both the EPI and the FLASH measurement, the left auditory cortex was more strongly involved than the right auditory cortex while participants categorized the intensity of FM tones. This was shown by a strong effect of the additional contralateral noise on the activity in the left auditory cortex. This means a massive reduction in background scanner noise still leads to a significant left lateralized effect. This suggests that the reversed lateralization in fMRI studies with loud background noise in contrast to studies with softer background cannot be fully explained by the MRI background noise.

  14. Interaction of Working Memory, Compressor Speed and Background Noise Characteristics

    DEFF Research Database (Denmark)

    Ohlenforst, Barbara; MacDonald, Ewen; Souza, Pamela

    Previous studies have shown that individuals with poor working memory perform worse in speech recognition tests when fast compression release time is applied. However, it is not clear why this effect occurs only when modulations are present in the background noise. This study explored...... the relationship between working memory capacity, compression release time and characteristics of the background noise. This relationship is important to understand because the majority of everyday listening situations involve modulated noise. The investigation was carried out by testing two groups of older adults...... with similar degrees of mild-­‐to-­‐moderate sensorineural loss but different working memory abilities. The two groups were tested in their ability to understand a speech signal presented within a modulated background noise, processed with slow and fast compression. The extent of background noise modulation...

  15. The effects of background white noise on memory performance in inattentive school children

    Directory of Open Access Journals (Sweden)

    Sikström Sverker

    2010-09-01

    Full Text Available Abstract Background Noise is typically conceived of as being detrimental for cognitive performance; however, a recent computational model based on the concepts of stochastic resonance and dopamine related internal noise postulates that a moderate amount of auditive noise benefit individuals in hypodopaminergic states. On the basis of this model we predicted that inattentive children would be enhanced by adding background white noise while attentive children's performance would deteriorate. Methods Fifty-one secondary school pupils carried out an episodic verbal free recall test in two noise conditions. In the high noise condition, verb-noun sentences were presented during auditory background noise (white noise, 78 dB, and in the low noise condition sentences were presented without noise. Results Exposure to background noise improved performance for inattentive children and worsened performance for attentive children and eliminated episodic memory differences between attentive and inattentive school children. Conclusions Consistent with the model, our data show that cognitive performance can be moderated by external background white noise stimulation in a non-clinical group of inattentive participants. This finding needs replicating in a larger sample using more noise levels but if replicated has great practical applications by offering a non-invasive way to improve school results in children with attentional problems.

  16. Background noise model development for seismic stations of KMA

    Science.gov (United States)

    Jeon, Youngsoo

    2010-05-01

    The background noise recorded at seismometer is exist at any seismic signal due to the natural phenomena of the medium which the signal passed through. Reducing the seismic noise is very important to improve the data quality in seismic studies. But, the most important aspect of reducing seismic noise is to find the appropriate place before installing the seismometer. For this reason, NIMR(National Institution of Meteorological Researches) starts to develop a model of standard background noise for the broadband seismic stations of the KMA(Korea Meteorological Administration) using a continuous data set obtained from 13 broadband stations during the period of 2007 and 2008. We also developed the model using short period seismic data from 10 stations at the year of 2009. The method of Mcmara and Buland(2004) is applied to analyse background noise of Korean Peninsula. The fact that borehole seismometer records show low noise level at frequency range greater than 1 Hz compared with that of records at the surface indicate that the cultural noise of inland Korean Peninsula should be considered to process the seismic data set. Reducing Double Frequency peak also should be regarded because the Korean Peninsula surrounded by the seas from eastern, western and southern part. The development of KMA background model shows that the Peterson model(1993) is not applicable to fit the background noise signal generated from Korean Peninsula.

  17. Data series subtraction with unknown and unmodeled background noise

    CERN Document Server

    Vitale, Stefano; Dolesi, Rita; Ferroni, Valerio; Hueller, Mauro; Vetrugno, Daniele; Weber, William Joseph; Audley, Heather; Danzmann, Karsten; Diepholz, Ingo; Hewitson, Martin; Korsakova, Natalia; Ferraioli, Luigi; Gibert, Ferran; Karnesis, Nikolaos; Nofrarias, Miquel; Inchauspe, Henri; Plagnol, Eric; Jennrich, Oliver; McNamara, Paul W; Armano, Michele; Thorpe, James Ira; Wass, Peter

    2014-01-01

    LISA Pathfinder (LPF), ESA's precursor mission to a gravitational wave observatory, will measure the degree to which two test-masses can be put into free-fall, aiming to demonstrate a residual relative acceleration with a power spectral density (PSD) below 30 fm/s$^2$/Hz$^{1/2}$ around 1 mHz. In LPF data analysis, the measured relative acceleration data series must be fit to other various measured time series data. This fitting is required in different experiments, from system identification of the test mass and satellite dynamics to the subtraction of noise contributions from measured known disturbances. In all cases, the background noise, described by the PSD of the fit residuals, is expected to be coloured, requiring that we perform such fits in the frequency domain. This PSD is unknown {\\it a priori}, and a high accuracy estimate of this residual acceleration noise is an essential output of our analysis. In this paper we present a fitting method based on Bayesian parameter estimation with an unknown frequ...

  18. Musical experience limits the degradative effects of background noise on the neural processing of sound.

    Science.gov (United States)

    Parbery-Clark, Alexandra; Skoe, Erika; Kraus, Nina

    2009-11-11

    Musicians have lifelong experience parsing melodies from background harmonies, which can be considered a process analogous to speech perception in noise. To investigate the effect of musical experience on the neural representation of speech-in-noise, we compared subcortical neurophysiological responses to speech in quiet and noise in a group of highly trained musicians and nonmusician controls. Musicians were found to have a more robust subcortical representation of the acoustic stimulus in the presence of noise. Specifically, musicians demonstrated faster neural timing, enhanced representation of speech harmonics, and less degraded response morphology in noise. Neural measures were associated with better behavioral performance on the Hearing in Noise Test (HINT) for which musicians outperformed the nonmusician controls. These findings suggest that musical experience limits the negative effects of competing background noise, thereby providing the first biological evidence for musicians' perceptual advantage for speech-in-noise.

  19. Elimination of the Background Noise of the Decoded Image in Fresnel Zone Plate Scanning Holography

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A method of digitally high pass filtering in frequency domain is proposed to eliminate the background noise of the decoded image in Fresnel zone plate scanning holography. The high pass filter is designed as a circular stop, which should be suitable to suppressing the background noise significantly and remain much low frequency information of the object. The principle of high pass filtering is that the Fourier transform of the decoded image is multiplied with the high pass filter. Thus the frequency spectrum of the decoded image without the background noise is achieved. By inverse Fourier transform of the spectrum of the decoded image after multiplying operation, the decoded image without the background noise is obtained. Both of the computer simulations and the experimental results show that the contrast and the signal-to-noise ratio of the decoded image are significantly improved with digital filtering.

  20. Background noise cancellation for improved acoustic detection of manatee vocalizations

    Science.gov (United States)

    Yan, Zheng; Niezrecki, Christopher; Beusse, Diedrich O.

    2005-06-01

    The West Indian manatee (Trichechus manatus latirostris) has become endangered partly because of an increase in the number of collisions with boats. A device to alert boaters of the presence of manatees, so that a collision can be avoided, is desired. A practical implementation of the technology is dependent on the hydrophone spacing and range of detection. These parameters are primarily dependent on the manatee vocalization strength, the decay of the signal's strength with distance, and the background noise levels. An efficient method to extend the detection range by using background noise cancellation is proposed in this paper. An adaptive line enhancer (ALE) that can detect and track narrow band signals buried in broadband noise is implemented to cancel the background noise. The results indicate that the ALE algorithm can efficiently extract the manatee calls from the background noise. The improved signal-to-noise ratio of the signal can be used to extend the range of detection of manatee vocalizations and reduce the false alarm and missing detection rate in their natural habitat. .

  1. History Document Image Background Noise and Removal Methods

    Directory of Open Access Journals (Sweden)

    Ganchimeg.G

    2015-12-01

    Full Text Available It is common for archive libraries to provide public access to historical and ancient document image collections. It is common for such document images to require specialized processing in order to remove background noise and become more legible. Document images may be contaminated with noise during transmission, scanning or conversion to digital form. We can categorize noises by identifying their features and can search for similar patterns in a document image to choose appropriate methods for their removal. In this paper, we propose a hybrid binarization approach for improving the quality of old documents using a combination of global and local thresholding. This article also reviews noises that might appear in scanned document images and discusses some noise removal methods.

  2. The method of narrow-band audio classification based on universal noise background model

    Science.gov (United States)

    Rui, Rui; Bao, Chang-chun

    2013-03-01

    Audio classification is the basis of content-based audio analysis and retrieval. The conventional classification methods mainly depend on feature extraction of audio clip, which certainly increase the time requirement for classification. An approach for classifying the narrow-band audio stream based on feature extraction of audio frame-level is presented in this paper. The audio signals are divided into speech, instrumental music, song with accompaniment and noise using the Gaussian mixture model (GMM). In order to satisfy the demand of actual environment changing, a universal noise background model (UNBM) for white noise, street noise, factory noise and car interior noise is built. In addition, three feature schemes are considered to optimize feature selection. The experimental results show that the proposed algorithm achieves a high accuracy for audio classification, especially under each noise background we used and keep the classification time less than one second.

  3. Study of the background noise in microwave GaAsFET devices

    Energy Technology Data Exchange (ETDEWEB)

    Serrano S, A. (Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, B.C. (Mexico))

    1984-01-01

    One of the most important properties of the gallium arsenide field effect transistor is its low noise figure in the microwave frequency range (approx. 1 dB, 4 GHz). The applications of this device in components and systems in the high frequency range require analysis of background noise in terms of basic static and dynamic properties of the device. The purpose of this paper is to review GaAsFET noise properties; from this review, a description of precise noise measurement techniques is made. Some experimental and theoretical results on the minimum noise figure are shown for several GaAsFET devices.

  4. Exploring the Relationship Between Working Memory, Compressor Speed, and Background Noise Characteristics

    DEFF Research Database (Denmark)

    Ohlenforst, Barbara; Souza, Pamela E.; MacDonald, Ewen

    2016-01-01

    to elicit such an effect is unknown. This study expanded on previous study by exploring the effect of background noise modulations in relation to compression speed and working memory ability, using a range of signal to noise ratios. Design: Twenty-six older participants between ages 61 and 90 years were...... grouped by high or low working memory according to their performance on a reading span test. Speech intelligibility was measured for low-context sentences presented in background noise, where the noise varied in the extent of amplitude modulation. Simulated fast- or slowacting compression amplification...... group behaved in the opposite way and performed better under slow compression compared with fast compression. There was also a significant effect of the extent of amplitude modulation in the background noise, such that the magnitude of the score difference (fast versus slow compression) depended...

  5. Effect of background noise on neuronal coding of interaural level difference cues in rat inferior colliculus

    Science.gov (United States)

    Mokri, Yasamin; Worland, Kate; Ford, Mark; Rajan, Ramesh

    2015-01-01

    Humans can accurately localize sounds even in unfavourable signal-to-noise conditions. To investigate the neural mechanisms underlying this, we studied the effect of background wide-band noise on neural sensitivity to variations in interaural level difference (ILD), the predominant cue for sound localization in azimuth for high-frequency sounds, at the characteristic frequency of cells in rat inferior colliculus (IC). Binaural noise at high levels generally resulted in suppression of responses (55.8%), but at lower levels resulted in enhancement (34.8%) as well as suppression (30.3%). When recording conditions permitted, we then examined if any binaural noise effects were related to selective noise effects at each of the two ears, which we interpreted in light of well-known differences in input type (excitation and inhibition) from each ear shaping particular forms of ILD sensitivity in the IC. At high signal-to-noise ratios (SNR), in most ILD functions (41%), the effect of background noise appeared to be due to effects on inputs from both ears, while for a large percentage (35.8%) appeared to be accounted for by effects on excitatory input. However, as SNR decreased, change in excitation became the dominant contributor to the change due to binaural background noise (63.6%). These novel findings shed light on the IC neural mechanisms for sound localization in the presence of continuous background noise. They also suggest that some effects of background noise on encoding of sound location reported to be emergent in upstream auditory areas can also be observed at the level of the midbrain. PMID:25865218

  6. Effect of background noise on neuronal coding of interaural level difference cues in rat inferior colliculus.

    Science.gov (United States)

    Mokri, Yasamin; Worland, Kate; Ford, Mark; Rajan, Ramesh

    2015-07-01

    Humans can accurately localize sounds even in unfavourable signal-to-noise conditions. To investigate the neural mechanisms underlying this, we studied the effect of background wide-band noise on neural sensitivity to variations in interaural level difference (ILD), the predominant cue for sound localization in azimuth for high-frequency sounds, at the characteristic frequency of cells in rat inferior colliculus (IC). Binaural noise at high levels generally resulted in suppression of responses (55.8%), but at lower levels resulted in enhancement (34.8%) as well as suppression (30.3%). When recording conditions permitted, we then examined if any binaural noise effects were related to selective noise effects at each of the two ears, which we interpreted in light of well-known differences in input type (excitation and inhibition) from each ear shaping particular forms of ILD sensitivity in the IC. At high signal-to-noise ratios (SNR), in most ILD functions (41%), the effect of background noise appeared to be due to effects on inputs from both ears, while for a large percentage (35.8%) appeared to be accounted for by effects on excitatory input. However, as SNR decreased, change in excitation became the dominant contributor to the change due to binaural background noise (63.6%). These novel findings shed light on the IC neural mechanisms for sound localization in the presence of continuous background noise. They also suggest that some effects of background noise on encoding of sound location reported to be emergent in upstream auditory areas can also be observed at the level of the midbrain.

  7. Reproduction of Realistic Background Noise for Testing Telecommunications Devices

    DEFF Research Database (Denmark)

    Gil Corrales, Juan David; Song, Wookeun; MacDonald, Ewen

    2015-01-01

    A method for reproduction of sound, based on crosstalk cancellation using inverse filters, was implemented in the context of testing telecommunications devices. The effect of the regularization parameter, number of loudspeakers, type of background noise, and a technique to attenuate audible...... artifacts, were investigated. The quality of the reproduced sound was evaluated both objectively and subjectively with respect to the reference sounds, at points where telecommunications devices would be potentially placed around the head. The highest regularization value gave the best results...

  8. 混合噪声下正弦参数估计互高阶谱MUSIC方法%Music Method of Cross High Order Spectrum for Sinusoidal Parameter Estimation on Hybrid Noise Background

    Institute of Scientific and Technical Information of China (English)

    兰华; 石要武; 金晟; 贾清泉; 敖丽敏

    2001-01-01

    Takes one dimension diagonal slice of cross high order accumulation as statistical element to demonstrate for the first time that cross high order accumulation is able to depress noncorrelative noises and correlative gauss noises. Signal vector space and noise vector space are established through characteristic decomposition, and a novel spectrum analysis method-cross high order spectrum MUSIC method is deduced to estimate sinusoidal parameters on background of hybrid noises. Simulation shows that on case of almost no pre-knowledge about noises, this method exhibits good spectrum estimating differentiability and stability. For low signal to noise ratio level is acceptable, this method is more applicable to practice.%采用互高阶累积量(互四阶累积量)的一维对角切片为统计量,首次证明了互高阶累积量可以有效地抑制非相关噪声和高斯噪声,并在建立互高阶累积量的Yule-Walker方程的基础上,通过特征分解,建立了信号矢量空间与噪声矢量空间,首次提出了混合噪声背景下正弦参数估计互高阶谱MUSIC方法。仿真结果说明,该方法在几乎不需要有色噪声的先验信息的条件下,具有良好的谱估计的分辨率和谱估计的稳定性。与其他方法比较,该方法抗干扰性更强,其信噪比工作门限低,特别适合于工程应用。

  9. Intelligent background noise reduction technology in cable fault locator using the magneto-acoustic synchronous method

    Science.gov (United States)

    Mi, JianWei; Huang, JiFa; Fang, XiaoLi; Fan, LiBin

    2017-01-01

    The magneto-acoustic synchronous method has found wide application in accurate positioning of power cable fault due to its advantages of high accuracy and strong ability to reject interference. In the view of principle, the magneto-acoustic synchronous method needs to detect the discharge sound signal and electromagnetic signal emitted from the fault point, but the discharge sound signal is easy to be interfered by the ambient noise around and the magnetic sound synchronization. Therefore, it is challenging to quickly and accurately detect the fault location of cable especially in strong background noise environment. On the other hand, the spectral subtraction is a relatively traditional and effective method in many intelligent background noise reduction technologies, which is characterized by a relatively small computational cost and strong real-time performance. However, its application is limited because the algorithm displays poor performance in low Signal to Noise Ratio (SNR) environment. Aiming at the shortcoming of the spectral subtraction that de-noising effect is weak in low SNR environment, this paper proposes an improved spectral subtraction combining the magnetic sound synchronous principle and analyzing the properties of discharging sound. This method can accurately estimate noise in real time and optimize the performance of the basic spectral subtraction thus solving the problem that the magneto-acoustic synchronous method is unsatisfactory for positioning cable fault in the strong background noise environment.

  10. 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.

  11. The Effect of Background Music and Background Noise on the Task Performance of Introverts and Extraverts

    Science.gov (United States)

    Cassidy, Gianna; MacDonald, Raymond A. R.

    2007-01-01

    The study investigated the effects of music with high arousal potential and negative affect (HA), music with low arousal potential and positive affect (LA), and everyday noise, on the cognitive task performance of introverts and extraverts. Forty participants completed five cognitive tasks: immediate recall, free recall, numerical and delayed…

  12. The Effect of Background Music and Background Noise on the Task Performance of Introverts and Extraverts

    Science.gov (United States)

    Cassidy, Gianna; MacDonald, Raymond A. R.

    2007-01-01

    The study investigated the effects of music with high arousal potential and negative affect (HA), music with low arousal potential and positive affect (LA), and everyday noise, on the cognitive task performance of introverts and extraverts. Forty participants completed five cognitive tasks: immediate recall, free recall, numerical and delayed…

  13. Influence of background noise on the performance in the odor sensitivity task: effects of noise type and extraversion.

    Science.gov (United States)

    Seo, Han-Seok; Hähner, Antje; Gudziol, Volker; Scheibe, Mandy; Hummel, Thomas

    2012-10-01

    Recent research demonstrated that background noise relative to silence impaired subjects' performance in a cognitively driven odor discrimination test. The current study aimed to investigate whether the background noise can also modulate performance in an odor sensitivity task that is less cognitively loaded. Previous studies have shown that the effect of background noise on task performance can be different in relation to degree of extraversion and/or type of noise. Accordingly, we wanted to examine whether the influence of background noise on the odor sensitivity task can be altered as a function of the type of background noise (i.e., nonverbal vs. verbal noise) and the degree of extraversion (i.e., introvert vs. extrovert group). Subjects were asked to conduct an odor sensitivity task in the presence of either nonverbal noise (e.g., party sound) or verbal noise (e.g., audio book), or silence. Overall, the subjects' mean performance in the odor sensitivity task was not significantly different across three auditory conditions. However, with regard to the odor sensitivity task, a significant interaction emerged between the type of background noise and the degree of extraversion. Specifically, verbal noise relative to silence significantly impaired or improved the performance of the odor sensitivity task in the introvert or extrovert group, respectively; the differential effect of introversion/extraversion was not observed in the nonverbal noise-induced task performance. In conclusion, our findings provide new empirical evidence that type of background noise and degree of extraversion play an important role in modulating the effect of background noise on subjects' performance in an odor sensitivity task.

  14. Fabry–Perot interferometer as a solar background noise suppressor: application to daytime lidar

    Directory of Open Access Journals (Sweden)

    Karnam Raghunath

    2012-06-01

    Full Text Available Continuous atmospheric probing by a lidar is a requirement for many applications. However, due to high solar background noise during the daytime, lidar operations are mostly restricted to night-time. While many techniques are in practice, like reducing the receiver field of view, changing the view angle, introducing a narrow band Interference Filter (IF, these are applied to circumvent problems, rather than to suppress the noise. Using a Fabry-Perot interferometer as a narrow passband filter for solar background noise suppression is a known technique, and its potential is exploited in our system. An optical-fiber-coupled lidar system with its transmitter injection seeded was developed and has been operated during the daytime at Gadanki (13.6˚N, 79.2˚ E. The signal-to-noise ratio of the return signal is used as the performance indicator, to evaluate the improvements. Signal-to-noise ratios with and without the Fabry-Perot interferometer are measured with near identical test set-ups. The signal-to-noise ratio enhancement factor is ca. 4, in agreement with the theoretical value. The performance is compared when the receiver fields of view are changed.

  15. Nonparametric VSS-APA based on precise background noise power estimate

    Institute of Scientific and Technical Information of China (English)

    昊翔; 赖晓翰; 陈隆道; 蔡忠法

    2015-01-01

    The adaptive algorithm used for echo cancellation (EC) system needs to provide 1) low misadjustment and 2) high convergence rate. The affine projection algorithm (APA) is a better alternative than normalized least mean square (NLMS) algorithm in EC applications where the input signal is highly correlated. Since the APA with a constant step-size has to make compromise between the performance criteria 1) and 2), a variable step-size APA (VSS-APA) provides a more reliable solution. A nonparametric VSS-APA (NPVSS-APA) is proposed by recovering the background noise within the error signal instead of cancelling the a posteriori errors. The most problematic term of its variable step-size formula is the value of background noise power (BNP). The power difference between the desired signal and output signal, which equals the power of error signal statistically, has been considered the BNP estimate in a rough manner. Considering that the error signal consists of background noise and misalignment noise, a precise BNP estimate is achieved by multiplying the rough estimate with a corrective factor. After the analysis on the power ratio of misalignment noise to background noise of APA, the corrective factor is formulated depending on the projection order and the latest value of variable step-size. The new algorithm which does not require any a priori knowledge of EC environment has the advantage of easier controllability in practical application. The simulation results in the EC context indicate the accuracy of the proposed BNP estimate and the more effective behavior of the proposed algorithm compared with other versions of APA class.

  16. Distinguishing Hypertrophic Cardiomyopathy-Associated Mutations from Background Genetic Noise

    Science.gov (United States)

    Kapplinger, Jamie D.; Landstrom, Andrew P.; Bos, J. Martijn; Salisbury, Benjamin A.; Callis, Thomas E.; Ackerman, Michael J.

    2014-01-01

    Despite the significant progress that has been made in identifying disease-associated mutations, the utility of the Hypertrophic Cardiomyopathy (HCM) genetic test is limited by a lack of understanding of the background genetic variation inherent to these sarcomeric genes in seemingly healthy subjects. This study represents the first comprehensive analysis of genetic variation in 427 ostensibly healthy individuals for the HCM genetic test using the “Gold Standard” Sanger sequencing method validating the background rate identified in the publically available exomes. While mutations are clearly over-represented in disease, a background rate as high as ~5% among healthy individuals prevents diagnostic certainty. To this end, we have identified a number of estimated predictive value-based associations including gene-specific, topology, and conservation methods generating an algorithm aiding in the probabilistic interpretation of an HCM genetic test. PMID:24510615

  17. A Low-Noise Germanium Ionization Spectrometer for Low-Background Science

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, Craig E.; Colaresi, Jim; Collar, Juan I.; Fast, James E.; Hossbach, Todd W.; Orrell, John L.; Overman, Cory T.; Scholz, Bjorn; Vandevender, Brent A.; Yocum, K. Michael

    2016-12-01

    Recent progress on the development of very low energy threshold high purity germanium ionization spectrometers has produced an instrument of 1.2 kg mass and excellent noise performance. The detector was installed in a low-background cryostat intended for use in a low mass, WIMP dark matter direct detection search. The integrated detector and low background cryostat achieved noise performance of 98 eV full-width half-maximum of an input electronic pulse generator peak and gamma-ray energy resolution of 1.9 keV full-width half-maximum at the 60Co gamma-ray energy of 1332 keV. This Transaction reports the thermal characterization of the low-background cryostat, specifications of the newly prepared 1.2 kg p-type point contact germanium detector, and the ionization spectroscopy – energy resolution and energy threshold – performance of the integrated system.

  18. Auditory nerve representation of a complex communication sound in background noise.

    Science.gov (United States)

    Simmons, A M; Schwartz, J J; Ferragamo, M

    1992-05-01

    A population study of auditory nerve responses in the bullfrog, Rana catesbeiana, analyzed the relative contributions of spectral and temporal coding in representing a complex, species-specific communication signal at different stimulus intensities and in the presence of background noise. At stimulus levels of 70 and 80 dB SPL, levels which approximate that received during communication in the natural environment, average rate profiles plotted over fiber characteristic frequency do not reflect the detailed spectral fine structure of the synthetic call. Rate profiles do not change significantly in the presence of background noise. In ambient (no noise) and low noise conditions, both amphibian papilla and basilar papilla fibers phase lock strongly to the waveform periodicity (fundamental frequency) of the synthetic advertisement call. The higher harmonic spectral fine structure of the synthetic call is not accurately reflected in the timing of fiber firing, because firing is "captured" by the fundamental frequency. Only a small number of fibers synchronize preferentially to any harmonic in the call other than the first, and none synchronize to any higher than the third, even when fiber characteristic frequency is close to one of these higher harmonics. Background noise affects fiber temporal responses in two ways: It can reduce synchronization to the fundamental frequency, until fiber responses are masked; or it can shift synchronization from the fundamental to the second or third harmonic of the call. This second effect results in a preservation of temporal coding at high noise levels. These data suggest that bullfrog eighth nerve fibers extract the waveform periodicity of multiple-harmonic stimuli primarily by a temporal code.

  19. Estimation of background noise level on seismic station using statistical analysis for improved analysis accuracy

    Science.gov (United States)

    Han, S. M.; Hahm, I.

    2015-12-01

    We evaluated the background noise level of seismic stations in order to collect the observation data of high quality and produce accurate seismic information. Determining of the background noise level was used PSD (Power Spectral Density) method by McNamara and Buland (2004) in this study. This method that used long-term data is influenced by not only innate electronic noise of sensor and a pulse wave resulting from stabilizing but also missing data and controlled by the specified frequency which is affected by the irregular signals without site characteristics. It is hard and inefficient to implement process that filters out the abnormal signal within the automated system. To solve these problems, we devised a method for extracting the data which normally distributed with 90 to 99% confidence intervals at each period. The availability of the method was verified using 62-seismic stations with broadband and short-period sensors operated by the KMA (Korea Meteorological Administration). Evaluation standards were NHNM (New High Noise Model) and NLNM (New Low Noise Model) published by the USGS (United States Geological Survey). It was designed based on the western United States. However, Korean Peninsula surrounded by the ocean on three sides has a complicated geological structure and a high population density. So, we re-designed an appropriate model in Korean peninsula by statistically combined result. The important feature is that secondary-microseism peak appeared at a higher frequency band. Acknowledgements: This research was carried out as a part of "Research for the Meteorological and Earthquake Observation Technology and Its Application" supported by the 2015 National Institute of Meteorological Research (NIMR) in the Korea Meteorological Administration.

  20. Chaotic system for the detection of periodic signals under the background of strong noise

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    We propose a method to study the chaotic system for the detection of periodic signals in the presence of strong background noise. The numerical experiments indicate that the chaotic system constructed from the modified Duffing-Holmes equation is sensitive to the weak periodic signal mixed with noise, and it has certain immunity to noise. The signal to noise ratio for the system can reach to about -91 dB.

  1. Background Noise Acceptance and Personality Factors Involved in Library Environment Choices by College Students

    Science.gov (United States)

    Gordon-Hickey, Susan; Lemley, Trey

    2012-01-01

    For decades, academic libraries made efforts to provide study environments differing in acoustic environment. The present study aimed to provide an evidence basis for this practice by comparing background noise acceptance and personality factors of two groups of college-aged students self identified as preferring quiet or background noise when…

  2. THE CHAOTIC DETECTION OF PERIODIC SHORT-IMPULSE SIGNALS UNDER STRONG NOISE BACKGROUND

    Institute of Scientific and Technical Information of China (English)

    Li Yue; Yang Baojun

    2002-01-01

    The periodic short-impulse signals under strong noise background are successfully detected with a special chaotic system invented by the authors. Simulation experiments show that the chaotic system is very sensitive to periodic short-impulse signals submerged by strong noise background, and it can effectively restrain any zero-mean noise. The system has a stable working-detection limit of -83dB.

  3. Impact of background noise and sentence complexity on cognitive processing demands

    DEFF Research Database (Denmark)

    Wendt, Dorothea; Dau, Torsten; Hjortkjær, Jens

    2015-01-01

    in 19 normal-hearing participants while processing sentences that were either syntactically simple or complex and presented in either high- or low-level background noise. Furthermore, the participants were asked to rate the subjectively perceived difficulty of sentence comprehension. The results showed......Speech comprehension in adverse listening conditions requires cognitive processingdemands. Processing demands can increase with acoustically degraded speech but also depend on linguistic aspects of the speech signal, such as syntactic complexity. In the present study, pupil dilations were recorded...... that increasing noise levels had a greater impact on the perceived difficulty than sentence complexity. In contrast, the processing of complex sentences resulted in greater and more prolonged pupil dilations. The results suggest that while pupil dilations may correlate with cognitive processing demands, acoustic...

  4. Impact of background noise and sentence complexity on cognitive processing effort

    DEFF Research Database (Denmark)

    Wendt, Dorothea; Dau, Torsten; Hjortkjær, Jens

    2015-01-01

    Speech comprehension in adverse listening conditions requires cognitive pro- cessing demands. Processing demands can increase with acoustically degraded speech but also depend on linguistic aspects of the speech signal, such as syntactic complexity. In the present study, pupil dilations were...... showed that increasing noise levels had a greater impact on the perceived difficulty than sentence complexity. In contrast, the processing of complex sentences resulted in greater and more prolonged pupil dilations. The results suggest that while pupil dilations may correlate with cognitive processing...... recorded in 19 normal-hearing participants while processing sentences that were either syntactically simple or complex and presented in either high- or low-level background noise. Furthermore, the participants were asked to rate the sub- jectively perceived difficulty of sentence comprehension. The results...

  5. Assessment of speech intelligibility in background noise and reverberation

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo

    impairment. In this thesis, two sentence-based tests for speech intelligibility in Danish were developed. The first test is the Conversational Language Understanding Evaluation (CLUE), which is based on the principles of the original American-English Hearing in Noise Test (HINT). The second test......, to measure whether the intelligibility of the test-word depends on the reverberation added to a surrounding speech carrier. It has been shown that the intelligibility of a reverberant test-word increases when the same amount of reverberation is also added to the carrier. In the literature, this observation......'s acoustic-phonetic properties. The evidence of the extrinsic compensation mechanism is therefore questionable. Overall, the results from the present study may contribute to the development of future speech intelligibility tests in Danish and other languages. The two developed sentence tests are expected...

  6. Weak lensing at the limit of the sky background noise

    CERN Document Server

    Mellier, Y

    1996-01-01

    Recent weak lensing observations have pushed the use of 4 meter-class telescopes to the limits of their capabilities with exposure times exceeding several hours. The leading idea is that the surface density of faint galaxies up to very faint magnitude ($B > 28-30$) raises continuously thus potentially offering a dense template of distant sources whose intensity contrast is at the sky noise level. In complement to the Peter Schneider's presentation on dark matter search from weak lensing (this conference), we review some of these recent advances in weak lensing analysis based on this extreme faint population of galaxies in order to explore: the dark matter distribution on large scales, the redshift ditribution of lensed sources at very large distance, and eventually the values of cosmological parameters. For each observational topic we will briefly discuss these new methods as compare to more classical lensing studies as well as the possible VLT scientific impact in the domain.

  7. High Octane Fuel: Terminal Backgrounder

    Energy Technology Data Exchange (ETDEWEB)

    Moriarty, Kristi [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-02-11

    The Bioenergy Technologies Office of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy sponsored a scoping study to assess the potential of ethanol-based high octane fuel (HOF) to reduce energy consumption and greenhouse gas emissions. When the HOF blend is made with 25%-40% ethanol by volume, this energy efficiency improvement is potentially sufficient to offset the reduced vehicle range often associated with the decreased volumetric energy density of ethanol. The purpose of this study is to assess the ability of the fuel supply chain to accommodate more ethanol at fuel terminals. Fuel terminals are midstream in the transportation fuel supply chain and serve to store and distribute fuels to end users. While there are no technical issues to storing more ethanol at fuel terminals, there are several factors that could impact the ability to deploy more ethanol. The most significant of these issues include the availability of land to add more infrastructure and accommodate more truck traffic for ethanol deliveries as well as a lengthy permitting process to erect more tanks.

  8. The impact of musicianship on the cortical mechanisms related to separating speech from background noise.

    Science.gov (United States)

    Zendel, Benjamin Rich; Tremblay, Charles-David; Belleville, Sylvie; Peretz, Isabelle

    2015-05-01

    Musicians have enhanced auditory processing abilities. In some studies, these abilities are paralleled by an improved understanding of speech in noisy environments, partially due to more robust encoding of speech signals in noise at the level of the brainstem. Little is known about the impact of musicianship on attention-dependent cortical activity related to lexical access during a speech-in-noise task. To address this issue, we presented musicians and nonmusicians with single words mixed with three levels of background noise, across two conditions, while monitoring electrical brain activity. In the active condition, listeners repeated the words aloud, and in the passive condition, they ignored the words and watched a silent film. When background noise was most intense, musicians repeated more words correctly compared with nonmusicians. Auditory evoked responses were attenuated and delayed with the addition of background noise. In musicians, P1 amplitude was marginally enhanced during active listening and was related to task performance in the most difficult listening condition. By comparing ERPs from the active and passive conditions, we isolated an N400 related to lexical access. The amplitude of the N400 was not influenced by the level of background noise in musicians, whereas N400 amplitude increased with the level of background noise in nonmusicians. In nonmusicians, the increase in N400 amplitude was related to a reduction in task performance. In musicians only, there was a rightward shift of the sources contributing to the N400 as the level of background noise increased. This pattern of results supports the hypothesis that encoding of speech in noise is more robust in musicians and suggests that this facilitates lexical access. Moreover, the shift in sources suggests that musicians, to a greater extent than nonmusicians, may increasingly rely on acoustic cues to understand speech in noise.

  9. Background noise levels and correlation with ship traffic in the Gulf of Catania

    Science.gov (United States)

    Viola, Salvatore; Buscaino, Giuseppa; Caruso, Francesco; Chierici, Francesco; Embriaco, Davide; Favali, Paolo; Giovanetti, Gabriele; Grammauta, Roasario; Larosa, Giuseppina; Pavan, Gianni; Pellegrino, Carmelo; Pulvirenti, Sara; Riccobene, Giorgio; Sciacca, Virginia; Simeone, Francesco; Beranzoli, Laura; Marinaro, Giuditta

    2015-04-01

    In the last decades the growing interest in the evaluation of the underwater acoustic noise for studies in the fields of geology, biology and high-energy physics is driving the scientific community to collaborate towards a multidisciplinary approach to the topic. In June 2012 in the framework of the European project EMSO, a multidisciplinary underwater observatory, named NEMO-SN1, was installed 25 km off-shore the port of Catania, at a depth of 2100 m and operated until May 2013 by INFN (Istituto Nazionale di Fisica Nucleare) and INGV (Istituto Nazionale di Geofisica e Vulcanologia). NEMO-SN1 hosted aboard geophysical, oceanographic and acoustic sensors: among these a seismic hydrophone model SMID DT-405D(V). In this work, conducted within the activity of the SMO project, the results on the evaluation of the underwater acoustic pollution in the Gulf of Catania through SMID DT-405D(V) recordings are presented. The seismic hydrophone provided a data set of about 11 months of continuous (24/7) recordings. Underwater sounds have been continuously digitized at a sampling frequency of 2 kHz and the acquired data have been stored in 10min long files for off-line analysis. To describe one-year background noise levels, the mean integrated acoustic noise was measured every second (sampling frequency 2000, NFFT 2048) in the 1/3 octave bands with centre frequency 63 Hz and for each 10 minutes-long file the 5th, the 50th and the 98th percentiles were calculated. Measured noise was correlated with the shipping traffic in the area, thanks to the data provided by an AIS receiver installed at the INFN-Laboratori Nazionali del Sud. An acoustic noise increment was measured in coincidence with the passing of crafts in the area and it was possible to identify the characteristic spectrum of each ship. A simple model for the estimation of the acoustic noise induced by the ships passing through the area was developed. The model was applied by using AIS data acquired during the operation

  10. Background noise analysis in urban airport surroundings of Brazilian cities, Congonhas Airport, São Paulo

    Directory of Open Access Journals (Sweden)

    Fabio Scatolini

    Full Text Available ABSTRACT OBJECTIVE To perform a quantitative analysis of the background noise at Congonhas Airport surroundings based on large sampling and measurements with no interruption. METHODS Measuring sites were chosen from 62 and 72 DNL (day-night-level noise contours, in urban sites compatible with residential use. Fifteen sites were monitored for at least 168 hours without interruption or seven consecutive days. Data compilation was based on cross-reference between noise measurements and air traffic control records, and results were validated by airport meteorological reports. Preliminary diagnoses were established using the standard NBR-13368. Background noise values were calculated based on the Sound Exposure Level (SEL. Statistic parameters were calculated in one-hour intervals. RESULTS Only four of the fifteen sites assessed presented aircraft operations as a clear cause for the noise annoyance. Even so, it is possible to detect background noise levels above regulation limits during periods of low airport activity or when it closes at night. CONCLUSIONS All the sites monitored showed background noise levels above regulation limits between 7:00 and 21:00. In the intervals between 6:00-6:59 and 21:00-22:59 the noise data, when analyzed with the current airport operational characteristics, still allow the development of additional mitigating measures.

  11. Effects of Background Noise on Cortical Encoding of Speech in Autism Spectrum Disorders

    Science.gov (United States)

    Russo, Nicole; Zecker, Steven; Trommer, Barbara; Chen, Julia; Kraus, Nina

    2009-01-01

    This study provides new evidence of deficient auditory cortical processing of speech in noise in autism spectrum disorders (ASD). Speech-evoked responses (approximately 100-300 ms) in quiet and background noise were evaluated in typically-developing (TD) children and children with ASD. ASD responses showed delayed timing (both conditions) and…

  12. Quantum noise properties of CT images with anatomical textured backgrounds across reconstruction algorithms: FBP and SAFIRE

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, Justin, E-mail: justin.solomon@duke.edu [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Samei, Ehsan [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Departments of Biomedical Engineering and Electrical and Computer Engineering, Pratt School of Engineering, Duke University, Durham, North Carolina 27705 (United States)

    2014-09-15

    Purpose: Quantum noise properties of CT images are generally assessed using simple geometric phantoms with uniform backgrounds. Such phantoms may be inadequate when assessing nonlinear reconstruction or postprocessing algorithms. The purpose of this study was to design anatomically informed textured phantoms and use the phantoms to assess quantum noise properties across two clinically available reconstruction algorithms, filtered back projection (FBP) and sinogram affirmed iterative reconstruction (SAFIRE). Methods: Two phantoms were designed to represent lung and soft-tissue textures. The lung phantom included intricate vessel-like structures along with embedded nodules (spherical, lobulated, and spiculated). The soft tissue phantom was designed based on a three-dimensional clustered lumpy background with included low-contrast lesions (spherical and anthropomorphic). The phantoms were built using rapid prototyping (3D printing) technology and, along with a uniform phantom of similar size, were imaged on a Siemens SOMATOM Definition Flash CT scanner and reconstructed with FBP and SAFIRE. Fifty repeated acquisitions were acquired for each background type and noise was assessed by estimating pixel-value statistics, such as standard deviation (i.e., noise magnitude), autocorrelation, and noise power spectrum. Noise stationarity was also assessed by examining the spatial distribution of noise magnitude. The noise properties were compared across background types and between the two reconstruction algorithms. Results: In FBP and SAFIRE images, noise was globally nonstationary for all phantoms. In FBP images of all phantoms, and in SAFIRE images of the uniform phantom, noise appeared to be locally stationary (within a reasonably small region of interest). Noise was locally nonstationary in SAFIRE images of the textured phantoms with edge pixels showing higher noise magnitude compared to pixels in more homogenous regions. For pixels in uniform regions, noise magnitude was

  13. THE CHAOTIC DETECTION OF PERIODIC SHORT—IMPULSE SIGNALS UNDER STRONG NOISE BACKGROUND

    Institute of Scientific and Technical Information of China (English)

    LiYue; YangBaojun

    2002-01-01

    The periodic short-impulse signals under strong noise background are successfully detected with a special chaotic system invented by the authors.Simulation experiments show that the chaotic system is very sensitive to periodic shor-impulse signals submerged by strong noise background,and it can effectively restrain any zero-mean nose.The system has a stable working-detection limit of -83dB.

  14. Fast High-Quality Noise

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Wyvill, Geoff

    2007-01-01

    At the moment the noise functions available in a graphics programmer's toolbox are either slow to compute or they involve grid-line artifacts making them of lower quality. In this paper we present a real-time noise computation with no grid-line artifacts or other regularity problems. In other wor...

  15. Objective Measures of Listening Effort: Effects of Background Noise and Noise Reduction

    Science.gov (United States)

    Sarampalis, Anastasios; Kalluri, Sridhar; Edwards, Brent; Hafter, Ervin

    2009-01-01

    Purpose: This work is aimed at addressing a seeming contradiction related to the use of noise-reduction (NR) algorithms in hearing aids. The problem is that although some listeners claim a subjective improvement from NR, it has not been shown to improve speech intelligibility, often even making it worse. Method: To address this, the hypothesis…

  16. Objective Measures of Listening Effort: Effects of Background Noise and Noise Reduction

    Science.gov (United States)

    Sarampalis, Anastasios; Kalluri, Sridhar; Edwards, Brent; Hafter, Ervin

    2009-01-01

    Purpose: This work is aimed at addressing a seeming contradiction related to the use of noise-reduction (NR) algorithms in hearing aids. The problem is that although some listeners claim a subjective improvement from NR, it has not been shown to improve speech intelligibility, often even making it worse. Method: To address this, the hypothesis…

  17. English vowel identification in quiet and noise: effects of listeners' native language background

    Science.gov (United States)

    Jin, Su-Hyun; Liu, Chang

    2014-01-01

    Purpose: To investigate the effect of listener's native language (L1) and the types of noise on English vowel identification in noise. Method: Identification of 12 English vowels was measured in quiet and in long-term speech-shaped noise and multi-talker babble (MTB) noise for English- (EN), Chinese- (CN) and Korean-native (KN) listeners at various signal-to-noise ratios (SNRs). Results: Compared to non-native listeners, EN listeners performed significantly better in quiet and in noise. Vowel identification in long-term speech-shaped noise and in MTB noise was similar between CN and KN listeners. This is different from our previous study in which KN listeners performed better than CN listeners in English sentence recognition in MTB noise. Discussion: Results from the current study suggest that depending on speech materials, the effect of non-native listeners' L1 on speech perception in noise may be different. That is, in the perception of speech materials with little linguistic cues like isolated vowels, the characteristics of non-native listener's native language may not play a significant role. On the other hand, in the perception of running speech in which listeners need to use more linguistic cues (e.g., acoustic-phonetic, semantic, and prosodic cues), the non-native listener's native language background might result in a different masking effect. PMID:25400538

  18. Background Noise Removal in Ultrasonic B-scan Images Using Iterative Statistical Techniques

    NARCIS (Netherlands)

    Wells, I.; Charlton, P. C.; Mosey, S.; Donne, K. E.

    2008-01-01

    The interpretation of ultrasonic B-scan images can be a time-consuming process and its success depends on operator skills and experience. Removal of the image background will potentially improve its quality and hence improve operator diagnosis. An automatic background noise removal algorithm is prop

  19. The Effects of Background Noise on Dichotic Listening to Consonant-Vowel Syllables

    Science.gov (United States)

    Sequeira, Sarah Dos Santos; Specht, Karsten; Hamalainen, Heikki; Hugdahl, Kenneth

    2008-01-01

    Lateralization of verbal processing is frequently studied with the dichotic listening technique, yielding a so called right ear advantage (REA) to consonant-vowel (CV) syllables. However, little is known about how background noise affects the REA. To address this issue, we presented CV-syllables either in silence or with traffic background noise…

  20. Asymptotics of high order noise corrections

    CERN Document Server

    Sondergaard, N; Pálla, G; Voros, A; Sondergaard, Niels; Vattay, Gabor; Palla, Gergely; Voros, Andre

    1999-01-01

    We consider an evolution operator for a discrete Langevin equation with a strongly hyperbolic classical dynamics and noise with finite moments. Using a perturbative expansion of the evolution operator we calculate high order corrections to its trace in the case of a quartic map and Gaussian noise. The leading contributions come from the period one orbits of the map. The asymptotic behaviour is investigated and is found to be independent up to a multiplicative constant of the distribution of noise.

  1. Dolphins adjust species-specific frequency parameters to compensate for increasing background noise.

    Science.gov (United States)

    Papale, Elena; Gamba, Marco; Perez-Gil, Monica; Martin, Vidal Martel; Giacoma, Cristina

    2015-01-01

    An increase in ocean noise levels could interfere with acoustic communication of marine mammals. In this study we explored the effects of anthropogenic and natural noise on the acoustic properties of a dolphin communication signal, the whistle. A towed array with four elements was used to record environmental background noise and whistles of short-beaked common-, Atlantic spotted- and striped-dolphins in the Canaries archipelago. Four frequency parameters were measured from each whistle, while Sound Pressure Levels (SPL) of the background noise were measured at the central frequencies of seven one-third octave bands, from 5 to 20 kHz. Results show that dolphins increase the whistles' frequency parameters with lower variability in the presence of anthropogenic noise, and increase the end frequency of their whistles when confronted with increasing natural noise. This study provides the first evidence that the synergy among SPLs has a role in shaping the whistles' structure of these three species, with respect to both natural and anthropogenic noise.

  2. A model of functional brain connectivity and background noise as a biomarker for cognitive phenotypes: application to autism.

    Directory of Open Access Journals (Sweden)

    Luis García Domínguez

    Full Text Available We present an efficient approach to discriminate between typical and atypical brains from macroscopic neural dynamics recorded as magnetoencephalograms (MEG. Our approach is based on the fact that spontaneous brain activity can be accurately described with stochastic dynamics, as a multivariate Ornstein-Uhlenbeck process (mOUP. By fitting the data to a mOUP we obtain: 1 the functional connectivity matrix, corresponding to the drift operator, and 2 the traces of background stochastic activity (noise driving the brain. We applied this method to investigate functional connectivity and background noise in juvenile patients (n = 9 with Asperger's syndrome, a form of autism spectrum disorder (ASD, and compared them to age-matched juvenile control subjects (n = 10. Our analysis reveals significant alterations in both functional brain connectivity and background noise in ASD patients. The dominant connectivity change in ASD relative to control shows enhanced functional excitation from occipital to frontal areas along a parasagittal axis. Background noise in ASD patients is spatially correlated over wide areas, as opposed to control, where areas driven by correlated noise form smaller patches. An analysis of the spatial complexity reveals that it is significantly lower in ASD subjects. Although the detailed physiological mechanisms underlying these alterations cannot be determined from macroscopic brain recordings, we speculate that enhanced occipital-frontal excitation may result from changes in white matter density in ASD, as suggested in previous studies. We also venture that long-range spatial correlations in the background noise may result from less specificity (or more promiscuity of thalamo-cortical projections. All the calculations involved in our analysis are highly efficient and outperform other algorithms to discriminate typical and atypical brains with a comparable level of accuracy. Altogether our results demonstrate a promising potential of

  3. Optimizing an infrasound sensor network for measuring acoustic background noise and its inversion for stratospheric winds

    Science.gov (United States)

    Marcillo, O. E.; Arrowsmith, S.

    2013-12-01

    We demonstrate the design of an infrasound network (and the associated analysis) for measuring and inverting low-frequency acoustic background noise (microbaroms) for stratospheric winds. We developed a mathematical framework for the inversion of local stratospheric winds using microbaroms, and found theoretical constraints on the optimum sensor network topology. Based on these results, we deployed, over the winter months (January to March, 2013), a prototype sensor network comprising six infrasound stations separated between 5 and 70 km; the initial analysis shows periods of very high coherency (suitable for our inversion) lasting several hours with associated tropospheric and low stratospheric celerities. We are analyzing the coherency between signals with distance and relative azimuth. Following this pilot study, we are designing a denser sensor network further optimized to capture microbaroms and planning for its validation using independent measurements.

  4. 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.

  5. Intrinsic noise of a superheated droplet detector for neutron background measurements in massively shielded facilities

    Science.gov (United States)

    Fernandes, Ana C.; Morlat, Tomoko A.; Felizardo, Miguel; Kling, Andreas; Marques, José G.; Prudêncio, Maria I.; Marques, Rosa; Carvalho, Fernando P.; Roche, Ignácio Lázaro; Girard, Thomas A.

    2017-09-01

    Superheated droplet detectors are a promising technique to the measurement of low-intensity neutron fields, as detectors can be rendered insensitive to minimum ionizing radiations. We report on the intrinsic neutron-induced signal of C2ClF5 devices fabricated by our group that originate from neutron- and alpha-emitting impurities in the detector constituents. The neutron background was calculated via Monte Carlo simulations using the MCNPX-PoliMi code in order to extract the recoil distributions following neutron interaction with the atoms of the superheated liquid. Various nuclear techniques were employed to characterise the detector materials with respect to source isotopes (238U, 232Th and 147Sm) for the normalisation of the simulations and also light elements (B, Li) having high (α, n) neutron production yields. We derived a background signal of 10-3 cts/day in a 1 liter detector of 1-3 wt.% C2ClF5, corresponding to a detection limit in the order of 10-8 n cm-2s-1. Direct measurements in a massively shielded underground facility for dark matter search have confirmed this result. With the borosilicate detector containers found to be the dominant background source in current detectors, possibilities for further noise reduction by 2 orders of magnitude based on selected container materials are discussed.

  6. Auditory-neurophysiological responses to speech during early childhood: Effects of background noise.

    Science.gov (United States)

    White-Schwoch, Travis; Davies, Evan C; Thompson, Elaine C; Woodruff Carr, Kali; Nicol, Trent; Bradlow, Ann R; Kraus, Nina

    2015-10-01

    Early childhood is a critical period of auditory learning, during which children are constantly mapping sounds to meaning. But this auditory learning rarely occurs in ideal listening conditions-children are forced to listen against a relentless din. This background noise degrades the neural coding of these critical sounds, in turn interfering with auditory learning. Despite the importance of robust and reliable auditory processing during early childhood, little is known about the neurophysiology underlying speech processing in children so young. To better understand the physiological constraints these adverse listening scenarios impose on speech sound coding during early childhood, auditory-neurophysiological responses were elicited to a consonant-vowel syllable in quiet and background noise in a cohort of typically-developing preschoolers (ages 3-5 yr). Overall, responses were degraded in noise: they were smaller, less stable across trials, slower, and there was poorer coding of spectral content and the temporal envelope. These effects were exacerbated in response to the consonant transition relative to the vowel, suggesting that the neural coding of spectrotemporally-dynamic speech features is more tenuous in noise than the coding of static features-even in children this young. Neural coding of speech temporal fine structure, however, was more resilient to the addition of background noise than coding of temporal envelope information. Taken together, these results demonstrate that noise places a neurophysiological constraint on speech processing during early childhood by causing a breakdown in neural processing of speech acoustics. These results may explain why some listeners have inordinate difficulties understanding speech in noise. Speech-elicited auditory-neurophysiological responses offer objective insight into listening skills during early childhood by reflecting the integrity of neural coding in quiet and noise; this paper documents typical response

  7. A high speed digital noise generator

    Science.gov (United States)

    Obrien, J.; Gaffney, B.; Liu, B.

    In testing of digital signal processing hardware, a high speed pseudo-random noise generator is often required to simulate an input noise source to the hardware. This allows the hardware to be exercised in a manner analogous to actual operating conditions. In certain radar and communication environments, a noise generator operating at speeds in excess of 60 MHz may be required. In this paper, a method of generating high speed pseudo-random numbers from an arbitrarily specified distribution (Gaussian, Log-Normal, etc.) using a transformation from a uniform noise source is described. A noise generator operating at 80 MHz has been constructed. Different distributions can be readily obtained by simply changing the ROM set. The hardware and test results will be described. Using this approach, the generation of pseudo-random sequences with arbitrary distributions at word rates in excess of 200 MHz can be readily achieved.

  8. Adaptive V/UV Speech Detection Based on Characterization of Background Noise

    Directory of Open Access Journals (Sweden)

    F. Beritelli

    2009-01-01

    Full Text Available The paper presents an adaptive system for Voiced/Unvoiced (V/UV speech detection in the presence of background noise. Genetic algorithms were used to select the features that offer the best V/UV detection according to the output of a background Noise Classifier (NC and a Signal-to-Noise Ratio Estimation (SNRE system. The system was implemented, and the tests performed using the TIMIT speech corpus and its phonetic classification. The results were compared with a nonadaptive classification system and the V/UV detectors adopted by two important speech coding standards: the V/UV detection system in the ETSI ES 202 212 v1.1.2 and the speech classification in the Selectable Mode Vocoder (SMV algorithm. In all cases the proposed adaptive V/UV classifier outperforms the traditional solutions giving an improvement of 25% in very noisy environments.

  9. Vibration transfers to measure the performance of vibration isolated platforms on site using background noise excitation

    NARCIS (Netherlands)

    Segerink, F.B.; Korterik, J.P.; Offerhaus, H.L.

    2011-01-01

    This article demonstrates a quick and easy way of quantifying the performance of a vibration-isolated platform. We measure the vibration transfer from floor to table using background noise excitation from the floor. As no excitation device is needed, our setup only requires two identical sensors (in

  10. Distinguishing Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia-Associated Mutations From Background Genetic Noise

    NARCIS (Netherlands)

    Kapplinger, Jamie D.; Landstrom, Andrew P.; Salisbury, Benjamin A.; Callis, Thomas E.; Pollevick, Guido D.; Tester, David J.; Cox, Moniek G. P. J.; Bhuiyan, Zahir; Bikker, Hennie; Wiesfeld, Ans C. P.; Hauer, Richard N. W.; van Tintelen, J. Peter; Jongbloed, Jan D. H.; Calkins, Hugh; Judge, Daniel P.; Wilde, Arthur A. M.; Ackerman, Michael J.

    2011-01-01

    Objectives The aims of this study were to determine the spectrum and prevalence of "background genetic noise" in the arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC) genetic test and to determine genetic associations that can guide the interpretation of a positive test result. Backgr

  11. Electromagnetic Compatibility (EMC) and Noise Background Testing for Double Chooz PMT System

    Energy Technology Data Exchange (ETDEWEB)

    Cepero, J. R.; Encabo Fernandez, F. J.; Pepe, I.; Verdugo, A.

    2009-05-21

    The Double Chooz PMT system is a HV/signal splitter. In this report is presented an electromagnetic compatibility and background noise testing for the Double Chooz PMT system. It was possible to proceed the EMC testing on different grounding configurations of PMT splitter due to its special PCB design, endowed of jumping points and a metal box ground electrode. (Author)

  12. The High Price of Noise Exposure

    Science.gov (United States)

    ... Issues Hearing Disorders The High Price of Noise Exposure Past Issues / Fall 2008 Table of Contents For ... on both loudness and time—the longer the exposure, the more likely the damage. In addition, the ...

  13. The Effect of Background Noise on the Word Activation Process in Nonnative Spoken-Word Recognition.

    Science.gov (United States)

    Scharenborg, Odette; Coumans, Juul M J; van Hout, Roeland

    2017-08-07

    This article investigates 2 questions: (1) does the presence of background noise lead to a differential increase in the number of simultaneously activated candidate words in native and nonnative listening? And (2) do individual differences in listeners' cognitive and linguistic abilities explain the differential effect of background noise on (non-)native speech recognition? English and Dutch students participated in an English word recognition experiment, in which either a word's onset or offset was masked by noise. The native listeners outperformed the nonnative listeners in all listening conditions. Importantly, however, the effect of noise on the multiple activation process was found to be remarkably similar in native and nonnative listening. The presence of noise increased the set of candidate words considered for recognition in both native and nonnative listening. The results indicate that the observed performance differences between the English and Dutch listeners should not be primarily attributed to a differential effect of noise, but rather to the difference between native and nonnative listening. Additional analyses showed that word-initial information was found to be more important than word-final information during spoken-word recognition. When word-initial information was no longer reliably available word recognition accuracy dropped and word frequency information could no longer be used suggesting that word frequency information is strongly tied to the onset of words and the earliest moments of lexical access. Proficiency and inhibition ability were found to influence nonnative spoken-word recognition in noise, with a higher proficiency in the nonnative language and worse inhibition ability leading to improved recognition performance. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  14. CS2 analysis in presence of non-Gaussian background noise - Effect on traditional estimators and resilience of log-envelope indicators

    Science.gov (United States)

    Borghesani, P.; Antoni, J.

    2017-06-01

    Second-order cyclostationary (CS2) analysis has become popular in the field of machine diagnostics and a series of digital signal processing techniques have been developed to extract CS2 components from the background noise. Among those techniques, squared envelope spectrum (SES) and cyclic modulation spectrum (CMS) have gained popularity thanks to their high computational efficiency and simple implementation. The effectiveness of CMS and SES has been previously quantified based on the hypothesis of Gaussian background noise and has led to statistical tests for the presence of CS2 peaks in squared envelope spectra and cyclic modulation spectra. However a recently established link of CMS with SES and of SES with kurtosis has exposed a potential weakness of those indicators in the case of highly leptokurtic background noise. This case is often present in practice when the machine is subjected to highly impulsive phenomena, either due to harsh operating conditions or to electric noise generated by power electronics and captured by the sensor. This study investigates and quantifies for the first time the effect of leptokurtic noise on the capabilities of SES and CMS, by analysing three progressively harsh situations: high kurtosis, infinite kurtosis and alpha-stable background noise (for which even first and second-order moments are not defined). Then the resilience of a recently proposed family of CS2 indicators, based on the log-envelope, is verified analytically, numerically and experimentally in the case of highly leptokurtic noise.

  15. Optimal cosmic microwave background map-making in the presence of cross-correlated noise

    Science.gov (United States)

    de Gasperis, G.; Buzzelli, A.; Cabella, P.; de Bernardis, P.; Vittorio, N.

    2016-08-01

    Aims: We present an extension of the ROMA map-making algorithm for the generation of optimal cosmic microwave background polarization maps. The new code allows for a possible cross-correlated noise component among the detectors of a CMB experiment. A promising application is the forthcoming LSPE balloon-borne experiment, which is devoted to the accurate observation of CMB polarization at large angular scales. Methods: We generalized the noise covariance matrix in time domain to account for all the off-diagonal terms due to the detector cross-talk. Hence, we performed preliminary forecasts of the LSPE-SWIPE instrument. Results: We found that considering the noise cross-correlation among the detectors results in a more realistic estimate of the angular power spectra. In particular, the extended ROMA algorithm has provided a considerable reduction of the spectra error bars. We expect that this improvement could be crucial in constraining the B-mode polarization at the largest scales.

  16. Assessing speech perception in children with language difficulties: effects of background noise and phonetic contrast.

    Science.gov (United States)

    Vance, Maggie; Martindale, Nicola

    2012-02-01

    Deficits in speech perception are reported for some children with language impairments. This deficit is more marked when listening against background noise. This study investigated the speech perception skills of young children with and without language difficulties. A speech discrimination task, using non-word minimal pairs in an XAB paradigm, was presented to 20 5-7-year-old children with language difficulties and 33 typically-developing (TD) children aged between 4- to 7-years. Stimuli were presented in quiet and in background noise (babble), and stimuli varied in phonetic contrasts, differing in either place of articulation or presence/absence of voicing. Children with language difficulties performed less well than TD children in all conditions. There was an interaction between group and noise condition, such that children with language difficulties were more affected by the presence of noise. Both groups of children made more errors with one voicing contrast /s z/ and there was some indication that children with language difficulties had proportionately greater difficulty with this contrast. Speech discrimination scores were significantly correlated with language scores for children with language difficulties. Issues in developing material for assessment of speech discrimination in children with LI are discussed.

  17. White-throated sparrows alter songs differentially in response to chorusing anurans and other background noise.

    Science.gov (United States)

    Lenske, Ariel K; La, Van T

    2014-06-01

    Animals can use acoustic signals to attract mates and defend territories. As a consequence, background noise that interferes with signal transmission has the potential to reduce fitness, especially in birds that rely on song. While much research on bird song has investigated vocal flexibility in response to urban noise, weather and other birds, the possibility of inter-class acoustic competition from anurans has not been previously studied. Using sound recordings from central Ontario wetlands, we tested if white-throated sparrows (Zonotrichia albicolis) make short-term changes to their singing behaviour in response to chorusing spring peepers (Pseudacris crucifer), as well as to car noise, wind and other bird vocalizations. White-throated sparrow songs that were sung during the spring peeper chorus were shorter with higher minimum frequencies and narrower bandwidths resulting in reduced frequency overlap. Additionally, sparrows were less likely to sing when car noise and the vocalizations of other birds were present. These patterns suggest that birds use multiple adjustment strategies. This is the first report to demonstrate that birds may alter their songs differentially in response to different sources of noise. This article is part of a Special Issue entitled: insert SI title.

  18. Effect of scanner acoustic background noise on strict resting-state fMRI

    Directory of Open Access Journals (Sweden)

    C. Rondinoni

    2013-04-01

    Full Text Available Functional MRI (fMRI resting-state experiments are aimed at identifying brain networks that support basal brain function. Although most investigators consider a ‘resting-state' fMRI experiment with no specific external stimulation, subjects are unavoidably under heavy acoustic noise produced by the equipment. In the present study, we evaluated the influence of auditory input on the resting-state networks (RSNs. Twenty-two healthy subjects were scanned using two similar echo-planar imaging sequences in the same 3T MRI scanner: a default pulse sequence and a reduced “silent” pulse sequence. Experimental sessions consisted of two consecutive 7-min runs with noise conditions (default or silent counterbalanced across subjects. A self-organizing group independent component analysis was applied to fMRI data in order to recognize the RSNs. The insula, left middle frontal gyrus and right precentral and left inferior parietal lobules showed significant differences in the voxel-wise comparison between RSNs depending on noise condition. In the presence of low-level noise, these areas Granger-cause oscillations in RSNs with cognitive implications (dorsal attention and entorhinal, while during high noise acquisition, these connectivities are reduced or inverted. Applying low noise MR acquisitions in research may allow the detection of subtle differences of the RSNs, with implications in experimental planning for resting-state studies, data analysis, and ergonomic factors.

  19. Removing 1/f noise stripes in cosmic microwave background anisotropy observations

    Science.gov (United States)

    Maino, D.; Burigana, C.; Górski, K. M.; Mandolesi, N.; Bersanelli, M.

    2002-05-01

    Removal of systematic effects is crucial in present and future CMB experiments mapping large fraction of the sky. Accurate CMB measurements ask for multi-feed array instruments observing the sky with a redundant scanning strategy covering the same sky region on different time scales and with different detectors for a better control of systematic effects. We investigate the capability to suppress 1/f noise features in Time Ordered Data (TOD) by using the destriping technique described in Maino et al. (1999), under realistic assumptions for crossing condition between different scan circles and sky signal fluctuations on small angular scales. We perform, as a working case, PLANCK-LFI simulated observations with few arcminutes pixel size convolved with LFI beam resolutions. In the noiseless case for crossing condition based on pixels with side larger than the input one, the destriping algorithm inserts extra-noise in the final map of the order of ~ mu K in rms and few mu K in peak-to-peak amplitude at 30 GHz. However including instrumental noise (white and 1/f noise) in the TOD, the impact of the sky signal on the destriping is found to be very small. In addition, for crossing condition based on pixels with side half of the one of the final map (typically ~ 1/3 of the FWHM), we find only a small improvement ( ~ 1% level) in the destriping quality with respect to the case when crossings are searched on pixels with same size of the final map one. We can conclude that the receiver noise is the driver for destriping quality. We extend the analysis to high values of the knee frequency and find that, although significantly suppressed by destriping, the residual additional noise rms is ~ 31% larger than the pure white noise rms at fk = 1 Hz which could be a critical issue in the extraction of CMB angular power spectrum. We verified that the approximation of the 1/f noise on averaged scan circles as a single baseline still works well even for these high values of the knee

  20. Regulation of Cortical Dynamic Range by Background Synaptic Noise and Feedforward Inhibition.

    Science.gov (United States)

    Khubieh, Ayah; Ratté, Stéphanie; Lankarany, Milad; Prescott, Steven A

    2016-08-01

    The cortex encodes a broad range of inputs. This breadth of operation requires sensitivity to weak inputs yet non-saturating responses to strong inputs. If individual pyramidal neurons were to have a narrow dynamic range, as previously claimed, then staggered all-or-none recruitment of those neurons would be necessary for the population to achieve a broad dynamic range. Contrary to this explanation, we show here through dynamic clamp experiments in vitro and computer simulations that pyramidal neurons have a broad dynamic range under the noisy conditions that exist in the intact brain due to background synaptic input. Feedforward inhibition capitalizes on those noise effects to control neuronal gain and thereby regulates the population dynamic range. Importantly, noise allows neurons to be recruited gradually and occludes the staggered recruitment previously attributed to heterogeneous excitation. Feedforward inhibition protects spike timing against the disruptive effects of noise, meaning noise can enable the gain control required for rate coding without compromising the precise spike timing required for temporal coding.

  1. The Reconstructing of Low Signal-noise Ratio Single Ion Channel Signal from Patch-clamp Recordings Sampled in the Colored Background Noise

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The single ion channel signal is an ionic current that can be recorded by the patch clamp technique. Hidden Markov model(HMM)algorithm has been used to convert the low signal-noise ra-tio (SNR) noisy recording into an idealized quantal one in the case of white background noise. The traditional HMM algorithm is extended and adapted to the colored background noise.A new algorithm called EHMM (Extended HMM) algorithm is proposed,and mainly validated by simulati-on.Results show that it's effective.

  2. Lung sounds auscultation technology based on ANC-ICA algorithm in high battlefield noise environment

    Institute of Scientific and Technical Information of China (English)

    牛海军; 冯安吉; 万明习; 白培瑞

    2003-01-01

    AIM:To explore the more accurate lung sounds auscultation technology in high battlefield noise environment.METHODS: In this study, we restrain high background noise using a new method-adaptive noise canceling based on independent component analysis (ANC-ICA), the method, by incorporating both second-order and higher-order statistics can remove noise components of the primary input signal based on statistical independence.RESULTS:The algorithm retained the local feature of lung sounds while eliminating high background noise, and performed more effectively than the conventional LMS algorithm.CONCLUSION:This method can cancel high battlefield noise of lung sounds effectively thus can help diagnose lung disease more accurately.

  3. Notionally steady background noise acts primarily as a modulation masker of speech.

    Science.gov (United States)

    Stone, Michael A; Füllgrabe, Christian; Moore, Brian C J

    2012-07-01

    Stone et al. [J. Acoust. Soc Am. 130, 2874-2881 (2011)], using vocoder processing, showed that the envelope modulations of a notionally steady noise were more effective than the envelope energy as a masker of speech. Here the same effect is demonstrated using non-vocoded signals. Speech was filtered into 28 channels. A masker centered on each channel was added to the channel signal at a target-to-background ratio of -5 or -10 dB. Maskers were sinusoids or noise bands with bandwidth 1/3 or 1 ERB(N) (ERB(N) being the bandwidth of "normal" auditory filters), synthesized with Gaussian (GN) or low-noise (LNN) statistics. To minimize peripheral interactions between maskers, odd-numbered channels were presented to one ear and even to the other. Speech intelligibility was assessed in the presence of each "steady" masker and that masker 100% sinusoidally amplitude modulated (SAM) at 8 Hz. Intelligibility decreased with increasing envelope fluctuation of the maskers. Masking release, the difference in intelligibility between the SAM and its "steady" counterpart, increased with bandwidth from near-zero to around 50 percentage points for the 1-ERB(N) GN. It is concluded that the sinusoidal and GN maskers behaved primarily as energetic and modulation maskers, respectively.

  4. Olfactory Performance Can Be Influenced by the Presentation Order, Background Noise, and Positive Concurrent Feedback.

    Science.gov (United States)

    Walliczek-Dworschak, Ute; Pellegrino, Robert; Lee, Shangwa; Hummel, Cornelia; Hähner, Antje; Hummel, Thomas

    2016-10-01

    Sniffin' Sticks have become a popular procedure to measure overall olfactory functionality with 3 subtest: phenyl ethyl alcohol threshold test (T), discrimination (D), and identification (I). However, several procedural components specified by the original paper have not been tested nor has the impact of deviations been measured. The aim of the present work was to measure olfactory performance under modified testing procedures. First, the reverse order of subtests (IDT) was compared with more standard practices (TDI). Next, the possible impact of background noise and positive concurrent feedback were assessed. A total of 120 individuals participated in the study where the 3 conditional experiments, each involving 40 participants, were completed. Testing procedures that reversed the presentation order of subtests (I->D->T) scored a significantly lower overall TDI score than standard testing order with the threshold subtest being the most influenced. Additionally, nonverbal background noise lowered overall olfactory performance while concurrent feedback modulated threshold performance. These results emphasize the importance of testing parameters where olfactory perception and tasks may be modulated by adaptation and attentional distraction, respectively. This study helped furthermore to demonstrate that the investigated 3 deviations from the standard procedure revealed a significant impact on the performance outcome in olfactory assessment using the Sniffin' Sticks.

  5. Speech-in-Noise Perception Deficit in Adults with Dyslexia: Effects of Background Type and Listening Configuration

    Science.gov (United States)

    Dole, Marjorie; Hoen, Michel; Meunier, Fanny

    2012-01-01

    Developmental dyslexia is associated with impaired speech-in-noise perception. The goal of the present research was to further characterize this deficit in dyslexic adults. In order to specify the mechanisms and processing strategies used by adults with dyslexia during speech-in-noise perception, we explored the influence of background type,…

  6. Speech understanding in background noise with the two-microphone adaptive beamformer BEAM in the Nucleus Freedom Cochlear Implant System.

    Science.gov (United States)

    Spriet, Ann; Van Deun, Lieselot; Eftaxiadis, Kyriaky; Laneau, Johan; Moonen, Marc; van Dijk, Bas; van Wieringen, Astrid; Wouters, Jan

    2007-02-01

    This paper evaluates the benefit of the two-microphone adaptive beamformer BEAM in the Nucleus Freedom cochlear implant (CI) system for speech understanding in background noise by CI users. A double-blind evaluation of the two-microphone adaptive beamformer BEAM and a hardware directional microphone was carried out with five adult Nucleus CI users. The test procedure consisted of a pre- and post-test in the lab and a 2-wk trial period at home. In the pre- and post-test, the speech reception threshold (SRT) with sentences and the percentage correct phoneme scores for CVC words were measured in quiet and background noise at different signal-to-noise ratios. Performance was assessed for two different noise configurations (with a single noise source and with three noise sources) and two different noise materials (stationary speech-weighted noise and multitalker babble). During the 2-wk trial period at home, the CI users evaluated the noise reduction performance in different listening conditions by means of the SSQ questionnaire. In addition to the perceptual evaluation, the noise reduction performance of the beamformer was measured physically as a function of the direction of the noise source. Significant improvements of both the SRT in noise (average improvement of 5-16 dB) and the percentage correct phoneme scores (average improvement of 10-41%) were observed with BEAM compared to the standard hardware directional microphone. In addition, the SSQ questionnaire and subjective evaluation in controlled and real-life scenarios suggested a possible preference for the beamformer in noisy environments. The evaluation demonstrates that the adaptive noise reduction algorithm BEAM in the Nucleus Freedom CI-system may significantly increase the speech perception by cochlear implantees in noisy listening conditions. This is the first monolateral (adaptive) noise reduction strategy actually implemented in a mainstream commercial CI.

  7. What is the influence of background noise and exercise on the listening levels of iPod users?

    Science.gov (United States)

    Hodgetts, William; Szarko, Ryan; Rieger, Jana

    2009-12-01

    The widespread use of portable listening devices (PLDs) has increased concern about the potential for hearing impairment caused by their use. The current study investigated the effects of external noise and exercise on the use of PLDs. The 24 participants listened to the same song on an iPod during rest-in-quiet, rest-in-noise, and exercise-in-noise conditions. Preferred listening levels (PLLs) were recorded and participants' maximum noise doses were calculated. Participants selected significantly higher listening levels in both noise conditions than in the quiet condition. The variability of volume selection was reduced significantly in the noise conditions. The maximum daily noise dose would have been exceeded by seven participants in the rest-in-noise condition and by eight in the exercise-in-noise condition compared to one participant in the rest-in-quiet condition. These results indicated that increased background noise causes individuals to increase the volume on their PLDs to potentially dangerous levels and that increased noise alone was not the only factor affecting the participants as the addition of exercise induced even further increases in PLLs.

  8. Background electromagnetic noise characterization: the role of external and internal Earth sources

    Directory of Open Access Journals (Sweden)

    Antonio Meloni

    2015-07-01

    Full Text Available The Earth is surrounded by the ionosphere and magnetosphere that can roughly be seen schematically as two concentric shells. These two composed and inhomogeneous structured shells around the Earth selectively affect electromagnetic (EM waves propagation. Both ionosphere and magnetosphere interact also with particles and waves coming from external sources, generating electromagnetic phenomena that in turn might become sources of EM waves. Conversely, EM waves generated inside the ionosphere remain confined at various altitudes in this region, up to a so-called critical frequency limit, depending on frequency, EM waves can escape out of the ionosphere and magnetosphere or get through. The EM waves generated inside the magnetospheric cavity mainly originate as a result of the electrical activity in the atmosphere. It is well known that also man-made sources, now widely spread on Earth, are a fundamental source of EM waves; however, excluding certain frequencies employed in power distribution and communication, man-made noise can be dominant only at local scale, near their source. According to recent studies, EM waves are also generated in the Earth’s lithosphere; these waves were sometimes associated with earthquake activity showing, on the Earth’s surface, intensities that are generally orders of magnitude below the background EM noise. In this review paper, we illustrate EM waves of natural origin and discuss their characterization in order to try discriminate those of lithospheric origin detectable at or near the Earth’s surface.

  9. Implications of conspecific background noise for features of blue tit, Cyanistes caeruleus , communication networks at dawn

    DEFF Research Database (Denmark)

    Poesel, Angelika; Dabelsteen, Torben; Pedersen, Simon Boel

    2007-01-01

    Abstract  Communication among animals often comprises several signallers and receivers within the signal's transmission range. In such communication networks, individuals can extract information about differences in relative performance of conspecifics by eavesdropping on their signalling...... interactions. In songbirds, information can be encoded in the timing of signals, which either alternate or overlap, and both male and female receivers may utilise this information when engaging in territorial interactions or making reproductive decisions, respectively. We investigated how conspecific...... background noise at dawn may overlay and possibly constrain the perception of such singing patterns. We simulated a small communication network of blue tits, Cyanistes caeruleus, at dawn in spring. Two loudspeakers simulated a singing interaction which was recorded from four different receiver positions...

  10. Removing 1/f noise stripes in cosmic microwave background anisotropy observations

    CERN Document Server

    Maino, D; Górski, K M; Mandolesi, N; Bersanelli, M

    2002-01-01

    Removal of systematic effects is crucial in present and future CMB experiments mapping large fraction of the sky. Accurate CMB measurements ask for multi-feed array instruments observing the sky with a redundant scanning strategy covering the same region of the sky on different time scales and with different detectors for a better control of systematic effects. We investigate here the capability to suppress 1/f noise features in Time Ordered Data (TOD) by using the destriping technique described in Maino et al. (1999), under realistic assumptions for crossing condition between different scan circles and sky signal fluctuations on small angular scales. We consider as working case, Planck-LFI simulated observations with few arminutes pixel size convolved with LFI beam resolutions. We also extend the analysis to high values of the knee-frequency and found a residual additional noise rms ~31% larger than the pure white noise rms at fk=1 Hz which could be a critical issue in the extraction of the CMB angular power...

  11. Noise from high speed maglev systems: Noise sources, noise criteria, preliminary design guidelines for noise control, and recommendations for acoustical test facility for maglev research

    Science.gov (United States)

    Hanson, C. E.; Abbot, P.; Dyer, I.

    1993-01-01

    Noise levels from magnetically-levitated trains (maglev) at very high speed may be high enough to cause environmental noise impact in residential areas. Aeroacoustic sources dominate the sound at high speeds and guideway vibrations generate noticeable sound at low speed. In addition to high noise levels, the startle effect as a result of sudden onset of sound from a rapidly moving nearby maglev vehicle may lead to increased annoyance to neighbors of a maglev system. The report provides a base for determining the noise consequences and potential mitigation for a high speed maglev system in populated areas of the United States. Four areas are included in the study: (1) definition of noise sources; (2) development of noise criteria; (3) development of design guidelines; and (4) recommendations for a noise testing facility.

  12. Noise of Embedded High Aspect Ratio Nozzles

    Science.gov (United States)

    Bridges, James E.

    2011-01-01

    A family of high aspect ratio nozzles were designed to provide a parametric database of canonical embedded propulsion concepts. Nozzle throat geometries with aspect ratios of 2:1, 4:1, and 8:1 were chosen, all with convergent nozzle areas. The transition from the typical round duct to the rectangular nozzle was designed very carefully to produce a flow at the nozzle exit that was uniform and free from swirl. Once the basic rectangular nozzles were designed, external features common to embedded propulsion systems were added: extended lower lip (a.k.a. bevel, aft deck), differing sidewalls, and chevrons. For the latter detailed Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) simulations were made to predict the thrust performance and to optimize parameters such as bevel length, and chevron penetration and azimuthal curvature. Seventeen of these nozzles were fabricated at a scale providing a 2.13 inch diameter equivalent area throat." ! The seventeen nozzles were tested for far-field noise and a few data were presented here on the effect of aspect ratio, bevel length, and chevron count and penetration. The sound field of the 2:1 aspect ratio rectangular jet was very nearly axisymmetric, but the 4:1 and 8:1 were not, the noise on their minor axes being louder than the major axes. Adding bevel length increased the noise of these nozzles, especially on their minor axes, both toward the long and short sides of the beveled nozzle. Chevrons were only added to the 2:1 rectangular jet. Adding 4 chevrons per wide side produced some decrease at aft angles, but increased the high frequency noise at right angles to the jet flow. This trend increased with increasing chevron penetration. Doubling the number of chevrons while maintaining their penetration decreased these effects. Empirical models of the parametric effect of these nozzles were constructed and quantify the trends stated above." Because it is the objective of the Supersonics Project that

  13. Music is as distracting as noise: the differential distraction of background music and noise on the cognitive test performance of introverts and extraverts.

    Science.gov (United States)

    Furnham, Adrian; Strbac, Lisa

    2002-02-20

    Previous research has found that introverts' performance on complex cognitive tasks is more negatively affected by distracters, e.g. music and background television, than extraverts' performance. This study extended previous research by examining whether background noise would be as distracting as music. In the presence of silence, background garage music and office noise, 38 introverts and 38 extraverts carried out a reading comprehension task, a prose recall task and a mental arithmetic task. It was predicted that there would be an interaction between personality and background sound on all three tasks: introverts would do less well on all of the tasks than extraverts in the presence of music and noise but in silence performance would be the same. A significant interaction was found on the reading comprehension task only, although a trend for this effect was clearly present on the other two tasks. It was also predicted that there would be a main effect for background sound: performance would be worse in the presence of music and noise than silence. Results confirmed this prediction. These findings support the Eysenckian hypothesis of the difference in optimum cortical arousal in introverts and extraverts.

  14. The impact of different background noises: effects on cognitive performance and perceived disturbance in employees with aided hearing impairment and normal hearing.

    Science.gov (United States)

    Hua, Håkan; Emilsson, Magnus; Kähäri, Kim; Widén, Stephen; Möller, Claes; Lyxell, Björn

    2014-10-01

    Health care professionals frequently meet employees with hearing impairment (HI) who experience difficulties at work. There are indications that the majority of these difficulties might be related to the presence of background noise. Moreover, research has also shown that high-level noise has a more detrimental effect on cognitive performance and self-rated disturbance in individuals with HI than low-level noise. The purpose of this study was to examine the impact of different types of background noise on cognitive performance and perceived disturbance (PD) in employees with aided HI and normal hearing. A mixed factorial design was conducted to examine the effect of noise in four experimental conditions. A total of 40 participants (21 men and 19 women) were recruited to take part in the study. The study sample consisted of employees with HI (n = 20) and normal hearing (n = 20). The group with HI had a mild-moderate sensorineural HI, and they were all frequent hearing-aid users. The current study was conducted by using four general work-related tasks (mental arithmetic, orthographic decoding, phonological decoding, and serial recall) in four different background conditions: (1) quiet, (2) office noise at 56 dBA, (3) daycare noise at 73.5 dBA, and (4) traffic noise at 72.5 dBA. Reaction time and the proportion of correct answers in the working tasks were used as outcome measures of cognitive performance. The Borg CR-10 scale was used to assess PD. Data collection occurred on two separate sessions, completed within 4 wk of each other. All tasks and experimental conditions were used in a counterbalanced order. Two-way analysis of variance with repeated measures was performed to analyze the results. To examine interaction effects, pairwise t-tests were used. Pearson correlation coefficients between reaction time and proportion of correct answers, and cognitive performance and PD were also calculated to examine the possible correlation between the different variables. No

  15. Effects of background noise on inter-trial phase coherence and auditory N1-P2 responses to speech stimuli.

    Science.gov (United States)

    Koerner, Tess K; Zhang, Yang

    2015-10-01

    This study investigated the effects of a speech-babble background noise on inter-trial phase coherence (ITPC, also referred to as phase locking value (PLV)) and auditory event-related responses (AERP) to speech sounds. Specifically, we analyzed EEG data from 11 normal hearing subjects to examine whether ITPC can predict noise-induced variations in the obligatory N1-P2 complex response. N1-P2 amplitude and latency data were obtained for the /bu/syllable in quiet and noise listening conditions. ITPC data in delta, theta, and alpha frequency bands were calculated for the N1-P2 responses in the two passive listening conditions. Consistent with previous studies, background noise produced significant amplitude reduction and latency increase in N1 and P2, which were accompanied by significant ITPC decreases in all the three frequency bands. Correlation analyses further revealed that variations in ITPC were able to predict the amplitude and latency variations in N1-P2. The results suggest that trial-by-trial analysis of cortical neural synchrony is a valuable tool in understanding the modulatory effects of background noise on AERP measures.

  16. Method of recognizing the high-speed railway noise barriers based on the distance image

    Science.gov (United States)

    Ma, Le; Shao, Shuangyun; Feng, Qibo; Liu, Bingqian; Kim, Chol Ryong

    2016-10-01

    The damage or lack of the noise barriers is one of the important hidden troubles endangering the safety of high-speed railway. In order to obtain the vibration information of the noise barriers, the online detection systems based on laser vision were proposed. The systems capture images of the laser stripe on the noise barriers and export data files containing distance information between the detection systems on the train and the noise barriers. The vibration status or damage of the noise barriers can be estimated depending on the distance information. In this paper, we focused on the method of separating the area of noise barrier from the background automatically. The test results showed that the proposed method is in good efficiency and accuracy.

  17. An investigation of cognitive test performance across conditions of silence, background noise and music as a function of neuroticism.

    OpenAIRE

    Reynolds, J.; McClelland, A; Furnham, A.

    2013-01-01

    The present study investigates the role of trait neuroticism on cognitive performance under distraction. Seventy participants were given a personality test and then undertook a number of different cognitive tasks in silence, in the presence of popular music and in background noise. It was predicted that performance on a general intelligence test, a test of abstract reasoning, and a mental arithmetic task would be adversely affected by background sounds. It was predicted that neuroticism would...

  18. An investigation of cognitive test performance across conditions of silence, background noise and music as a function of neuroticism

    OpenAIRE

    Reynolds, James; McClelland, Alastair; Furnham, Adrian

    2013-01-01

    The present study investigates the role of trait neuroticism on cognitive performance under distraction. Seventy participants were given a personality test and then undertook a number of different cognitive tasks in silence, in the presence of popular music and in background noise. It was predicted that performance on a general intelligence test, a test of abstract reasoning, and a mental arithmetic task would be adversely affected by background sounds. It was predicted that neuroticism would...

  19. Analysis of external noise spectrum of high-speed railway

    Institute of Scientific and Technical Information of China (English)

    邓永权; 肖新标; 何宾; 金学松

    2014-01-01

    A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteristics considered here include identifying the exterior main sources and their locations, their frequency components including the Doppler effect due to the noise sources moving at high speed, the sound field intensity around the train in high-speed operation, the sound radiation path out of the train, and the pressure level and frequency components of the noise at the measuring points specified by the International Organization for Standardization(ISO). The characteristics of the high-speed train exterior noise of the high speed railways in operation were introduced. The advanced measuring systems and their principles for clearly indentifying the exterior noise sources were discussed in detail. Based on the concerned noise results measured at sites, a prediction model was developed to calculate the sound level and the characteristics of the exterior noise at any point where it is difficult to measure and to help to make the exterior noise spectrums. This model was also verified with the test results. The verification shows that there is a good agreement between the theoretical and experimental results.

  20. The effects of background noise on the neural responses to natural sounds in cat primary auditory cortex

    Directory of Open Access Journals (Sweden)

    Omer Bar-Yosef

    2007-11-01

    Full Text Available Animal vocalizations in natural settings are invariably accompanied by an acoustic background with a complex statistical structure. We have previously demonstrated that neuronal responses in primary auditory cortex of halothane-anesthetized cats depend strongly on the natural background. Here, we study in detail the neuronal responses to the background sounds and their relationships to the responses to the foreground sounds. Natural bird chirps as well as modifications of these chirps were used. The chirps were decomposed into three components: the clean chirps, their echoes, and the background noise. The last two were weaker than the clean chirp by 13 and 29 dB on average respectively. The test stimuli consisted of the full natural stimulus, the three basic components, and their three pairwise combinations. When the level of the background components (echoes and background noise presented alone was sufficiently loud to evoke neuronal activity, these background components had an unexpectedly strong effect on the responses of the neurons to the main bird chirp. In particular, the responses to the original chirps were more similar on average to the responses evoked by the two background components than to the responses evoked by the clean chirp, both in terms of the evoked spike count and in terms of the temporal pattern of the responses. These results suggest that some of the neurons responded specifically to the acoustic background even when presented together with the substantially louder main chirp, and may imply that neurons in A1 already participate in auditory source segregation.

  1. An investigation of cognitive test performance across conditions of silence, background noise and music as a function of neuroticism.

    Science.gov (United States)

    Reynolds, James; McClelland, Alastair; Furnham, Adrian

    2014-01-01

    The present study investigates the role of trait neuroticism on cognitive performance under distraction. Seventy participants were given a personality test and then undertook a number of different cognitive tasks in silence, in the presence of popular music and in background noise. It was predicted that performance on a general intelligence test, a test of abstract reasoning, and a mental arithmetic task would be adversely affected by background sounds. It was predicted that neuroticism would be negatively correlated with performance on the mental arithmetic task but only when the individuals were working in the presence of background sound. Stable vs. unstable participant's performance on a mental arithmetic task during noise was significantly higher as predicted. The results provided partial support for the hypotheses and are discussed with respect to previous findings in the literature on personality (particularly introversion-extraversion) and distraction on cognitive task performance. Limitations are noted.

  2. Study on low-phase-noise optoelectronic oscillator and high-sensitivity phase noise measurement system.

    Science.gov (United States)

    Hong, Jun; Liu, An-min; Guo, Jian

    2013-08-01

    An analytic model for an injection-locked dual-loop optoelectronic oscillator (OEO) is proposed and verified by experiments in this paper. Based on this theoretical model, the effect of injection power on the single-sideband phase noise of the OEO is analyzed, and results suggest that moderate injection is one key factor for a balance between phase noise and spur for OEO. In order to measure superlow phase noise of OEOs, a cross-correlation measurement system based on the fiber delay line is built, in which high linear photodetector and low-phase-noise amplifier are used to improve systematic sensitivity. The cross-correlation measurement system is validated by experiments, and its noise floor for the X band is about -130 dBc/Hz at 1 kHz and -168 dBc/Hz at 10 kHz after a cross correlation of 200 times.

  3. Research on Aerodynamic Noise Reduction for High-Speed Trains

    Directory of Open Access Journals (Sweden)

    Yadong Zhang

    2016-01-01

    Full Text Available A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD/Ffowcs Williams-Hawkings (FW-H acoustic analogy. An analysis of noise reduction methods based on the main noise sources was performed. An aerodynamic noise model for a full-scale high-speed train, including three coaches with six bogies, two inter-coach spacings, two windscreen wipers, and two pantographs, was established. Several low-noise design improvements for the high-speed train were identified, based primarily on the main noise sources; these improvements included the choice of the knuckle-downstream or knuckle-upstream pantograph orientation as well as different pantograph fairing structures, pantograph fairing installation positions, pantograph lifting configurations, inter-coach spacings, and bogie skirt boards. Based on the analysis, we designed a low-noise structure for a full-scale high-speed train with an average sound pressure level (SPL 3.2 dB(A lower than that of the original train. Thus, the noise reduction design goal was achieved. In addition, the accuracy of the aerodynamic noise calculation method was demonstrated via experimental wind tunnel tests.

  4. What will Europa sound like? Modeling seismic background noise due to tidal cracking events

    Science.gov (United States)

    Panning, M. P.; Stähler, S. C.; Huang, H. H.; Vance, S.; Kedar, S.; Lorenz, R. D.; Pike, W. T.

    2016-12-01

    Seismology is a powerful tool for illuminating internal structure and dynamics in planetary bodies. With the plan for a Europa lander next decade, we have the opportunity to place a seismometer on the surface and greatly increase our knowledge of internal structure of the ocean world. In order to maximize return from such an instrument, we need to understand both predicted signals and noise. Instrument noise can be quantified well on Earth, but estimating the ambient noise of a planetary body is significantly more challenging. For Europa, we make an initial range of estimates of ambient noise due to ongoing tidally induced events within the ice shell. We estimate a range of cumulative moment releases based on tidal dissipation energy, and then create an assumed Gutenberg-Richter relationship (e.g. Golombek et al., 1992). We then use this relationship to generate random realizations of event catalogs with a length of 1 day, including all events down to a moment magnitude of -1, and generate continuous 3 component seismic records from these catalogs using a spectral element method (Instaseis/AxiSEM, van Driel et al., 2015). The seismic data are calculated using a range of thermodynamically self-consistent layered models of Europa structure, varying ice shell thickness and attenuation (e.g. Cammarano et al., 2006). The noise records are then used to define overall spectral characteristics of the noise and to test methods to take advantage of the ambient noise, such as autocorrelation techniques. Ambient noise characteristics are also compared with candidate instrument noise models which may be included in future Europa missions. F. Cammarano, V. Lekic, M. Manga, M.P. Panning, and B.A. Romanowicz (2006), "Long-period seismology on Europa: 1. Physically consistent interior models," J. Geophys. Res., 111, E12009, doi: 10.1029/2006JE002710. M. van Driel, L. Krischer, S.C. Stähler, K. Hosseini, and T. Nissen-Meyer (2015), "Instaseis: instant global seismograms based on a

  5. The protective effect of moderate noisy backgrounds for certain period on hearing after exposure to a traumatic noise in guinea pig

    Directory of Open Access Journals (Sweden)

    Xiao-hua WANG

    2013-03-01

    Full Text Available Objective  To investigate the protective effect of moderate noisy backgrounds on guinea pig's hearing after an exposure to a traumatic noise. Methods  Thirty guinea pigs were randomly divided into five groups (6 each. Animals in group A, B, C and D were subjected to noise of 84 decibels sound pressure level (dB SPL for 4, 8, 24 and 0 hour respectively after a traumatic exposure of 110 dB SPL, and those in group E were kept in quiet environment. Distortion product oto-acoustic emission (DPOAE amplitudes were determined on 1 day prior, and 1 and 7 days after noise exposure. Blood plasma was obtained to determine the contents of malondialdehyde (MDA and the activities of hemocuprein (SOD and nitricoxide synthase (NOS at the end of the experiment. Results  Noise-induced hearing loss was caused in group D after a traumatic exposure. At the 1st and 7th day after exposure, DPOAE amplitudes were higher in group A and B than in group D, especially at high frequencies, while no significant difference was observed between group C and D. At the 7th day after exposure, the activity of SOD lowered, while the content of MDA increased in group A and B as compared with group E (P<0.05. The content of MDA in group A increased as compared with group D (P<0.05. Conclusion  After the traumatic noise-exposure, the recovery of noise-induced hearing loss, especially the high-frequency hearing loss could be motivated when exposed to noise at 84 dB SPL for 4 or 8 hours.

  6. Impact of Background Noise and Sentence Complexity on Processing Demands during Sentence Comprehension

    DEFF Research Database (Denmark)

    Wendt, Dorothea; Dau, Torsten; Hjortkjær, Jens

    2016-01-01

    Speech comprehension in adverse listening conditions can be effortful even when speech is fully intelligible. Acoustical distortions typically make speech comprehension more effortful, but effort also depends on linguistic aspects of the speech signal, such as its syntactic complexity...... and less by syntactic complexity. Conversely, pupil dilations increased with syntactic complexity but only showed a small effect of the noise level. Participants with higher WMC showed increased pupil responses in the higher-level noise condition but rated sentence comprehension as being less effortful...

  7. Noise of high-performance aircraft at afterburner

    Science.gov (United States)

    Tam, Christopher K. W.; Parrish, Sarah A.

    2015-09-01

    The noise from a high-performance aircraft at afterburner is investigated. The main objective is to determine whether the dominant noise components are the same or similar to those of a hot supersonic laboratory jet. For this purpose, measured noise data from F-22A Raptors are analyzed. It is found, based on both spectral and directivity data, that there is a new dominant noise component in addition to the usual turbulent mixing noise. The characteristic features of the new noise component are identified. Measured data indicates that the new noise component is observed only when the rate of fuel burn of the engine is increased significantly above that of the intermediate power setting. This suggests that the new noise component is combustion related. The possibility that it is indirect combustion noise generated by the passage of hot spots from the afterburner through the nozzle of the jet is investigated. Because flow and temperature data were not measured in the F-22A engine tests, to provide support to the proposition, numerical simulations of indirect combustion noise generation due to the passing of an entropy wave pulse (a hot spot) through a military-style nozzle are carried out. Sound generation is observed at the front and at the back of the pulse. This creates a fast and a slow acoustic wave as the sound radiates out from the nozzle exit. Quantitative estimates of the principal directions of acoustic radiation due to the emitted fast and slow acoustic waves are made. It is found that there are reasonably good agreements with measured data. To estimate the intensity level (IL) of the radiated indirect combustion noise, a time-periodic entropy wave train of 15 percent temperature fluctuation is used as a model of the hot spots coming out of the afterburner. This yields an IL of 175.5 dB. This is a fairly intense noise source, well capable of causing the radiation of the new jet noise component.

  8. Overcoming High Energy Backgrounds at Pulsed Spallation Sources

    CERN Document Server

    Cherkashyna, Nataliia; DiJulio, Douglas D.; Khaplanov, Anton; Pfeiffer, Dorothea; Scherzinger, Julius; Cooper-Jensen, Carsten P.; Fissum, Kevin G.; Ansell, Stuart; Iverson, Erik B.; Ehlers, Georg; Gallmeier, Franz X.; Panzner, Tobias; Rantsiou, Emmanouela; Kanaki, Kalliopi; Filges, Uwe; Kittelmann, Thomas; Extegarai, Maddi; Santoro, Valentina; Kirstein, Oliver; Bentley, Phillip M.

    2015-01-01

    Instrument backgrounds at neutron scattering facilities directly affect the quality and the efficiency of the scientific measurements that users perform. Part of the background at pulsed spallation neutron sources is caused by, and time-correlated with, the emission of high energy particles when the proton beam strikes the spallation target. This prompt pulse ultimately produces a signal, which can be highly problematic for a subset of instruments and measurements due to the time-correlated properties, and different to that from reactor sources. Measurements of this background have been made at both SNS (ORNL, Oak Ridge, TN, USA) and SINQ (PSI, Villigen, Switzerland). The background levels were generally found to be low compared to natural background. However, very low intensities of high-energy particles have been found to be detrimental to instrument performance in some conditions. Given that instrument performance is typically characterised by S/N, improvements in backgrounds can both improve instrument pe...

  9. Research on Aerodynamic Noise Reduction for High-Speed Trains

    OpenAIRE

    Yadong Zhang; Jiye Zhang; Tian Li; Liang Zhang; Weihua Zhang

    2016-01-01

    A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H)...

  10. Research on Aerodynamic Noise Reduction for High-Speed Trains

    OpenAIRE

    Yadong Zhang; Jiye Zhang; Tian Li; Liang Zhang; Weihua Zhang

    2016-01-01

    A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H)...

  11. 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 ...

  12. Assessment of rural soundscapes with high-speed train noise.

    Science.gov (United States)

    Lee, Pyoung Jik; Hong, Joo Young; Jeon, Jin Yong

    2014-06-01

    In the present study, rural soundscapes with high-speed train noise were assessed through laboratory experiments. A total of ten sites with varying landscape metrics were chosen for audio-visual recording. The acoustical characteristics of the high-speed train noise were analyzed using various noise level indices. Landscape metrics such as the percentage of natural features (NF) and Shannon's diversity index (SHDI) were adopted to evaluate the landscape features of the ten sites. Laboratory experiments were then performed with 20 well-trained listeners to investigate the perception of high-speed train noise in rural areas. The experiments consisted of three parts: 1) visual-only condition, 2) audio-only condition, and 3) combined audio-visual condition. The results showed that subjects' preference for visual images was significantly related to NF, the number of land types, and the A-weighted equivalent sound pressure level (LAeq). In addition, the visual images significantly influenced the noise annoyance, and LAeq and NF were the dominant factors affecting the annoyance from high-speed train noise in the combined audio-visual condition. In addition, Zwicker's loudness (N) was highly correlated with the annoyance from high-speed train noise in both the audio-only and audio-visual conditions. © 2013.

  13. Effects of Age-Related Hearing Loss and Background Noise on Neuromagnetic Activityfrom Auditory Cortex

    Directory of Open Access Journals (Sweden)

    Claude eAlain

    2014-01-01

    Full Text Available Aging is often accompanied by hearing loss, which impacts how sounds are processed and represented along the ascending auditory pathways and within the auditory cortices. Here, we assess the impact of mild binaural hearing loss on the older adults’ ability to both process complex sounds embedded in noise and segregate a mistuned harmonic in an otherwise periodic stimulus. We measured auditory evoked fields (AEFs using magnetoencephalography while participants were presented with complex tones that had either all harmonics in tune or had the third harmonic mistuned by 4 or 16% of its original value. The tones (75 dB sound pressure level, SPL were presented without, with low (45 dBA, SPL or with moderate (65 dBA SPL Gaussian noise. For each participant, we modeled the AEFs with a pair of dipoles in the superior temporal plane. We then examined the effects of hearing loss and noise on the amplitude and latency of the resulting source waveforms. In the present study, results revealed that similar noise-induced increases in N1m were present in older adults with and without hearing loss. Our results also showed that the P1m amplitude was larger in the hearing impaired than normal-hearing adults. In addition, the object-related negativity (ORN elicited by the mistuned harmonic was larger in hearing impaired listeners. The enhanced P1m and ORN amplitude in the hearing impaired older adults suggests that hearing loss increased neural excitability in auditory cortices, which could be related to deficits in inhibitory control.

  14. A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement.

    Science.gov (United States)

    Zhou, Haijun; Yang, Wenhai; Li, Zhixiu; Li, Xuefeng; Zheng, Yaohui

    2014-01-01

    We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO4 laser at 1064 nm with coherent output. The measured shot noise of 50 μW laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearities for both DC and AC amplifications in the laser power range between 12.5 μW and 1.52 mW.

  15. A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Haijun; Yang, Wenhai; Li, Zhixiu; Li, Xuefeng; Zheng, Yaohui, E-mail: yhzheng@sxu.edu.cn [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China)

    2014-01-15

    We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO{sub 4} laser at 1064 nm with coherent output. The measured shot noise of 50 μW laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearities for both DC and AC amplifications in the laser power range between 12.5 μW and 1.52 mW.

  16. Long-term ELF background noise measurements, the existence of window regions, and applications to earthquake precursor emission studies

    Science.gov (United States)

    Dea, Jack Y.; Hansen, Peder M.; Boerner, Wolfgang-M.

    1993-04-01

    A Low Frequency Monitoring Network has been under development at Naval Command, Control and Ocean Surveillance Center (NCCOSC), Research, Development, Test and Evaluation Division (RDT & E), San Diego, CA, for the last 2 years. Originally developed to monitor space vehicle induced signatures in the 5-12 Hz region, the network now includes monitoring of anomolous broadband signals in the 0.1-20 Hz region that often precede the occurrence of nearby earthquakes. Observations of such events have led to a hypothesis that geological signals are normally present in the ULF (ultra-low frequency, less than 3 Hz) and ELF (extremely low frequency, 3-3000 Hz) bands in addition to the generally accepted signals from micropulsations and lightning discharges. In Southern California, the geological signals are best observed in the 'polarimetric window' regions of (i) 2-5 Hz using horizontally oriented magnetic sensors and, (ii) 2-20 Hz using vertically oriented magnetic sensors. To determine the significance of anomalous events, we conducted a statistical study of the background noise levels. Observations of daily records over a span of several months indicated that the background level in the 1-20 Hz region is stationary. Stationarity is not true below 1 Hz. The APD (amplitude probability density) of 2-12 Hz signals was found to be surprisingly close to a Gaussian distribution. These two results indicated that a determination of long-term averages and variances would be meaningful. Long-term averages and variances were obtained and were used to develop alert-level criteria. Typical deviations over the course of several hours are 1 to 2 dB. The alert-level criteria are used as input parameters in our Automated Monitoring System (AMS), a computerized monitoring and real-time analysis system. The alert levels warn the operator when unusual events are occurring. High alert-levels in conjunction with the fulfilment of several other conditions often presage the occurrence of an

  17. High frequency microseismic noise as possible earthquake precursor

    Directory of Open Access Journals (Sweden)

    Ivica Sović

    2013-08-01

    Full Text Available Before an earthquake occurs, microseismic noise in high frequency (HF range, i.e. 2-25 Hz, is being generated during preparation process. These signals change the microseismic noise and, consequently, the spectrum of microseismic noise. Time variation of spectra recorded at the same seismological station could imply the change of the state of noise source. We propose the image moment analysis approach to objectively compare microseismic noise spectra. The result could be used for earthquake precursor identification. Expected spectra change is in HF range, so the analysis has been limited to the shallow tectonic earthquakes with epicenters close, up to 15 km, the seismological stations. The method has been tested post festum using four earthquakes in Dinarides which satisfied condition for epicentral distance. The spectra were calculated for noise recorded in time intervals of 10 days before and 6 to 10 days after the earthquakes. Affine moment invariants were calculated for noise spectra which were treated as the input objects. Spectra of the first five days in the series were referent spectra. The classification parameters were Euclidean distances between referent spectra and the spectra for all days in the series, including referent ones. The results have shown that the spectra of the microseismic noise become noticeably different than the other spectra in time intervals one or two days before an earthquake.

  18. High-resolution noise radar using slow ADC

    Science.gov (United States)

    Lukin, Konstantin; Vyplavin, Pavlo; Zemlyanyi, Oleg; Lukin, Sergiy; Palamarchuk, Volodymyr

    2011-06-01

    Conventional digital signal processing scheme in noise radars has some limitations related to combination of high resolution and high dynamic range. Those limitations are caused by a tradeoff in performance of currently available ADCs: the faster is ADC the smaller is its depth (number of bits) available. Depth of the ADC determines relation between the smallest and highest observable signals and thus limits its dynamic range. In noise radar with conventional processing the sounding and reference signals are to be digitized at intermediate frequency band and to be processed digitally. The power spectrum bandwidth of noise signal which can be digitized with ADC depends on its sampling rate. The bandwidth of radar signal defines range resolution of any radar: the wider the spectrum the better the resolution. Actually this is the main bottleneck of high resolution Noise Radars: conventional processing doesn't enable to get both high range resolution and high dynamic range. In the paper we present a way to go around this drawback by changing signal processing ideology in noise radar. We present results of our consideration and design of high resolution Noise Radar which uses slow ADCs. The design is based upon generation of both probing and reference signals digitally and realization of their cross-correlation in an analog correlator. The output of the correlator is a narrowband signal that requires rather slow ADC to be sampled which nowadays may give up to 130 dB dynamic range.

  19. The role of binary mask patterns in automatic speech recognition in background noise.

    Science.gov (United States)

    Narayanan, Arun; Wang, DeLiang

    2013-05-01

    Processing noisy signals using the ideal binary mask improves automatic speech recognition (ASR) performance. This paper presents the first study that investigates the role of binary mask patterns in ASR under various noises, signal-to-noise ratios (SNRs), and vocabulary sizes. Binary masks are computed either by comparing the SNR within a time-frequency unit of a mixture signal with a local criterion (LC), or by comparing the local target energy with the long-term average spectral energy of speech. ASR results show that (1) akin to human speech recognition, binary masking significantly improves ASR performance even when the SNR is as low as -60 dB; (2) the ASR performance profiles are qualitatively similar to those obtained in human intelligibility experiments; (3) the difference between the LC and mixture SNR is more correlated to the recognition accuracy than LC; (4) LC at which the performance peaks is lower than 0 dB, which is the threshold that maximizes the SNR gain of processed signals. This broad agreement with human performance is rather surprising. The results also indicate that maximizing the SNR gain is probably not an appropriate goal for improving either human or machine recognition of noisy speech.

  20. CT urography in the urinary bladder: To compare excretory phase images using a low noise index and a high noise index with adaptive noise reduction filter

    Energy Technology Data Exchange (ETDEWEB)

    Takeyama, Nobuyuki; Hayashi, Takaki (Dept. of Radiology, Showa Univ. Fujigaoka Hospital, Yokohama (Japan)), email: momiji@mtc.biglobe.ne.jp; Ohgiya, Yoshimitsu (Dept. of Radiology, Showa Univ. School of Medicine, Tokyo (Japan)) (and others)

    2011-07-15

    Background: Although CT urography (CTU) is widely used for the evaluation of the entire urinary tract, the most important drawback is the radiation exposure. Purpose: To evaluate the effect of a noise reduction filter (NRF) using a phantom and to quantitatively and qualitatively compare excretory phase (EP) images using a low noise index (NI) with those using a high NI and postprocessing NRF (pNRF). Material and Methods: Each NI value was defined for a slice thickness of 5 mm, and reconstructed images with a slice thickness of 1.25 mm were assessed. Sixty patients who were at high risk of developing bladder tumors (BT) were divided into two groups according to whether their EP images were obtained using an NI of 9.88 (29 patients; group A) or an NI of 20 and pNRF (31 patients; group B). The CT dose index volume (CTDI{sub vol}) and the contrast-to-noise ratio (CNR) of the bladder with respect to the anterior pelvic fat were compared in both groups. Qualitative assessment of the urinary bladder for image noise, sharpness, streak artifacts, homogeneity, and the conspicuity of polypoid or sessile-shaped BTs with a short-axis diameter greater than 10 mm was performed using a 3-point scale. Results: The phantom study showed noise reduction of approximately 40% and 76% dose reduction between group A and group B. CTDI{sub vol} demonstrated a 73% reduction in group B (4.6 +- 1.1 mGy) compared with group A (16.9 +- 3.4 mGy). The CNR value was not significantly different (P = 0.60) between group A (16.1 +- 5.1) and group B (16.6 +- 7.6). Although group A was superior (P < 0.01) to group B with regard to image noise, other qualitative analyses did not show significant differences. Conclusion: EP images using a high NI and pNRF were quantitatively and qualitatively comparable to those using a low NI, except with regard to image noise

  1. Background Radiation Measurements at High Power Research Reactors

    CERN Document Server

    Ashenfelter, J; Baldenegro, C X; Band, H R; Barclay, G; Bass, C D; Berish, D; Bowden, N S; Bryan, C D; Cherwinka, J J; Chu, R; Classen, T; Davee, D; Dean, D; Deichert, G; Dolinski, M J; Dolph, J; Dwyer, D A; Fan, S; Gaison, J K; Galindo-Uribarri, A; Gilje, K; Glenn, A; Green, M; Han, K; Hans, S; Heeger, K M; Heffron, B; Jaffe, D E; Kettell, S; Langford, T J; Littlejohn, B R; Martinez, D; McKeown, R D; Morrell, S; Mueller, P E; Mumm, H P; Napolitano, J; Norcini, D; Pushin, D; Romero, E; Rosero, R; Saldana, L; Seilhan, B S; Sharma, R; Stemen, N T; Surukuchi, P T; Thompson, S J; Varner, R L; Wang, W; Watson, S M; White, B; White, C; Wilhelmi, J; Williams, C; Wise, T; Yao, H; Yeh, M; Yen, Y -R; Zhang, C; Zhang, X

    2016-01-01

    Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including $\\gamma$-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

  2. Background radiation measurements at high power research reactors

    Energy Technology Data Exchange (ETDEWEB)

    Ashenfelter, J. [Wright Laboratory, Department of Physics, Yale University, New Haven, CT 06520 (United States); Balantekin, B. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Baldenegro, C.X. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Band, H.R. [Wright Laboratory, Department of Physics, Yale University, New Haven, CT 06520 (United States); Barclay, G. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bass, C.D. [Department of Chemistry and Physics, Le Moyne College, Syracuse, NY 13214 (United States); Berish, D. [Department of Physics, Temple University, Philadelphia, PA 19122 (United States); Bowden, N.S., E-mail: nbowden@llnl.gov [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Bryan, C.D. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Cherwinka, J.J. [Physical Sciences Laboratory, University of Wisconsin, Madison, WI 53706 (United States); Chu, R. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Classen, T. [Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Davee, D. [Department of Physics, College of William and Mary, Williamsburg, VA 23187 (United States); Dean, D.; Deichert, G. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Dolinski, M.J. [Department of Physics, Drexel University, Philadelphia, PA 19104 (United States); Dolph, J. [Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Dwyer, D.A. [Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Fan, S. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); and others

    2016-01-11

    Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

  3. Noise Measurements of High Aspect Ratio Distributed Exhaust Systems

    Science.gov (United States)

    Bridges, James E.

    2015-01-01

    This paper covers far-field acoustic measurements of a family of rectangular nozzles with aspect ratio 8, in the high subsonic flow regime. Several variations of nozzle geometry, commonly found in embedded exhaust systems, are explored, including bevels, slants, single broad chevrons and notches, and internal septae. Far-field acoustic results, presented previously for the simple rectangular nozzle, showed that increasing aspect ratio increases the high frequency noise, especially directed in the plane containing the minor axis of the nozzle. Detailed changes to the nozzle geometry generally made little difference in the noise, and the differences were greatest at low speed. Having an extended lip on one broad side (bevel) did produce up to 3 decibels more noise in all directions, while extending the lip on the narrow side (slant) produced up to 2 decibels more noise, primarily on the side with the extension. Adding a single, non-intrusive chevron, made no significant change to the noise, while inverting the chevron (notch) produced up to 2decibels increase in the noise. Having internal walls (septae) within the nozzle, such as would be required for structural support or when multiple fan ducts are aggregated, reduced the noise of the rectangular jet, but could produce a highly directional shedding tone from the septae trailing edges. Finally, a nozzle with both septae and a beveled nozzle, representative of the exhaust system envisioned for a distributed electric propulsion aircraft with a common rectangular duct, produced almost as much noise as the beveled nozzle, with the septae not contributing much reduction in noise.

  4. Effect of Background Noise on the Photon Statistics of Triggered Single Molecules

    Institute of Scientific and Technical Information of China (English)

    XIAO Lian-Tuan; ZHAO Yan-Ting; HUANG Tao; ZHAO Jian-Ming; YIN Wang-Bao; JIA Suo-Tang

    2004-01-01

    @@ We theoretically derive exact expressions for Mandel's Q parameter of the triggered single molecular source, which is inferred from the probabilities PRS(n) using the recorded of each photon detection event based on Hanbury Brown and Twiss detection. The real triggered source is recognized as an ideal single photon source with a Poissonian statistics background. How to decease the background and to increase the efficiency are discussed. It is established that the sub-Poissonian statistics formation can be determined by comparing the measured QRS of the real single triggered molecular with QC of the Poissonian source containing the same mean photons. By this method, we also give an efficient way to measure signal-to-background ratios of triggered single photons.

  5. Contribution of resolved and unresolved harmonic regions to brainstem speech-evoked responses in quiet and in background noise

    Directory of Open Access Journals (Sweden)

    M. Laroche

    2011-03-01

    Full Text Available Speech auditory brainstem responses (speech ABR reflect activity that is phase-locked to the harmonics of the fundamental frequency (F0 up to at least the first formant (F1. Recent evidence suggests that responses at F0 in the presence of noise are more robust than responses at F1, and are also dissociated in some learning-impaired children. Peripheral auditory processing can be broadly divided into resolved and unresolved harmonic regions. This study investigates the contribution of these two regions to the speech ABR, and their susceptibility to noise. We recorded, in quiet and in background white noise, evoked responses in twelve normal hearing adults in response to three variants of a synthetic vowel: i Allformants, which contains all first three formants, ii F1Only, which is dominated by resolved harmonics, and iii F2&F3Only, which is dominated by unresolved harmonics. There were no statistically significant differences in the response at F0 due to the three variants of the stimulus in quiet, nor did the noise affect this response with the Allformants and F1Only variants. On the other hand, the response at F0 with the F2&F3Only variant was significantly weaker in noise than with the two other variants (p<0.001. With the response at F1, there was no difference with the Allformants and F1Only variants in quiet, but was expectedly weaker with the F2&F3Only variant (p<0.01. The addition of noise significantly weakened the response at F1 with the F1Only variant (p<0.05, but this weakening only tended towards significance with the Allformants variant (p=0.07. The results of this study indicate that resolved and unresolved harmonics are processed in different but interacting pathways that converge in the upper brainstem. The results also support earlier work on the differential susceptibility of responses at F0 and F1 to added noise.

  6. EXTRAGALACTIC VERY HIGH ENERGY GAMMA-RAY BACKGROUND

    Energy Technology Data Exchange (ETDEWEB)

    Neronov, A. [ISDC Data Center for Astrophysics, Chemin d' Ecogia 16, CH-1290 Versoix (Switzerland); Semikoz, D. V. [APC, 10 rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France)

    2012-09-20

    We study the origin of the extragalactic diffuse gamma-ray background using the data from the Fermi telescope. To estimate the background level, we count photons at high Galactic latitudes |b| > 60 Degree-Sign . Subtracting photons associated with known sources and the residual cosmic-ray and Galactic diffuse backgrounds, we estimate the extragalactic gamma-ray background (EGB) flux. We find that the spectrum of EGB in the very high energy band above 30 GeV follows the stacked spectrum of BL Lac objects. Large Area Telescope data reveal the positive (1 + z) {sup k}, 1 < k < 4 cosmological evolution of the BL Lac source population consistent with that of their parent population, Fanaroff-Riley type I radio galaxies. We show that EGB at E > 30 GeV could be completely explained by emission from unresolved BL Lac objects if k {approx_equal} 3.

  7. MDT Performance in a High Rate Background Environment

    CERN Document Server

    Aleksa, Martin; Hessey, N P; Riegler, W

    1998-01-01

    A Cs137 gamma source with different lead filters in the SPS beam-line X5 has been used to simulate the ATLAS background radiation. This note shows the impact of high background rates on the MDT efficiency and resolution for three kinds of pulse shaping and compares the results with GARFIELD simulations. Furthermore it explains how the performance can be improved by time slewing corrections and double track separation.

  8. The impact of simulated MRI scanner background noise on visual attention processes as measured by the EEG.

    Science.gov (United States)

    Kobald, S Oliver; Getzmann, Stephan; Beste, Christian; Wascher, Edmund

    2016-06-21

    Environmental noise is known to affect personal well-being as well as cognitive processes. Besides daily life, environmental noise can also occur in experimental research settings, e.g. when being in a magnetic resonance scanner. Scanner background noise (SBN) might pose serious confounds for experimental findings, even when non-auditory settings are examined. In the current experiment we tested if SBN alters bottom-up and top-down related processes of selective visual attention mechanisms. Participants completed two blocks of a visual change detection task, one block in silence and one block under SBN exposure. SBN was found to decrease accuracy in measures of visual attention. This effect was modulated by the temporal occurrence of SBN. When SBN was encountered in the first block, it prevented a significant improvement of accuracy in the second block. When SBN appeared in the second block, it significantly decreased accuracy. Neurophysiological findings showed a strong frontal positivity shift only when SBN was present in the first block, suggesting an inhibitory process to counteract the interfering SBN. Common correlates of both top-down and bottom-up processes of selective visual attention were not specifically affected by SBN exposure. Further research appears necessary to entirely rule out confounds of SBN in assessing visual attention.

  9. The impact of simulated MRI scanner background noise on visual attention processes as measured by the EEG

    Science.gov (United States)

    Kobald, S. Oliver; Getzmann, Stephan; Beste, Christian; Wascher, Edmund

    2016-01-01

    Environmental noise is known to affect personal well-being as well as cognitive processes. Besides daily life, environmental noise can also occur in experimental research settings, e.g. when being in a magnetic resonance scanner. Scanner background noise (SBN) might pose serious confounds for experimental findings, even when non-auditory settings are examined. In the current experiment we tested if SBN alters bottom-up and top-down related processes of selective visual attention mechanisms. Participants completed two blocks of a visual change detection task, one block in silence and one block under SBN exposure. SBN was found to decrease accuracy in measures of visual attention. This effect was modulated by the temporal occurrence of SBN. When SBN was encountered in the first block, it prevented a significant improvement of accuracy in the second block. When SBN appeared in the second block, it significantly decreased accuracy. Neurophysiological findings showed a strong frontal positivity shift only when SBN was present in the first block, suggesting an inhibitory process to counteract the interfering SBN. Common correlates of both top-down and bottom-up processes of selective visual attention were not specifically affected by SBN exposure. Further research appears necessary to entirely rule out confounds of SBN in assessing visual attention. PMID:27324456

  10. Educational Background and High School Maths Teachers ‘Specialism

    Directory of Open Access Journals (Sweden)

    Lin. Wang

    2009-10-01

    Full Text Available Teachers’ Specialism is a world development trend and fashion, but also the needs and the direction of teacher education reform. After the latest curriculum reform, the educational reform and development of math,teachers have become universally concentrated and thoughtful in the field of mathematical education. The study adopting questionnaires and telephone interviews carried out a sample survey to 59 common high school math teachers from 3 provinces, and analyzed the connection between math teachers’ specialism and educational background by the statistical analysis tool SPSS quantitatively and qualitatively. The study shows that both mathematical science knowledge and mathematical educational skills have an obvious connection with the educational background, while there’s little connection between mathematical educational knowledge and the educational background. The study points out a relevant strategy which high school math teachers should attach the same important to pre-job training and post-job training

  11. Seeking Solution: High-Performance Computing for Science. Background Paper.

    Science.gov (United States)

    Congress of the U.S., Washington, DC. Office of Technology Assessment.

    This is the second publication from the Office of Technology Assessment's assessment on information technology and research, which was requested by the House Committee on Science and Technology and the Senate Committee on Commerce, Science, and Transportation. The first background paper, "High Performance Computing & Networking for…

  12. An ultra-low noise, high-voltage piezo driver

    CERN Document Server

    Pisenti, N C; Reschovsky, B J; Barker, D S; Campbell, G K

    2016-01-01

    We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switching noise, yielding a total RMS noise of $\\approx 100\\mu$V (1 Hz--100 kHz). A low-voltage ($\\pm 10$V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both repeatable setpoints and sophisticated control logic, and the circuit consumes less than 150mA at $\\pm 15$V.

  13. Quantum dot amplifiers with high output power and low noise

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2003-01-01

    Quantum dot semiconductor optical amplifiers have been theoretically investigated and are predicted to achieve high saturated output power, large gain, and low noise figure. We discuss the device dynamics and, in particular, show that the presence of highly inverted barrier states does not limit ...

  14. Hearing Protection for High-Noise Environments

    Science.gov (United States)

    2009-12-31

    based on a modified form of the volumetric Lippmann- Schwinger integral equation, adapted to the treatment of high-contrast problems. It utilizes a...the reformulation of the conventional Lippmann- Schwinger (L-S) equations which we developed in the case of acoustics (Reference 2 in Section 6). By

  15. Precise muon drift tube detectors for high background rate conditions

    CERN Document Server

    Engl, Albert; Dünnweber, Wolfgang

    The muon spectrometer of the ATLAS-experiment at the Large H adron Collider consists of drift tube chambers, which provide the precise m easurement of trajec- tories of traversing muons. In order to determine the moment um of the muons with high precision, the measurement of the position of the m uon in a single tube has to be more accurate than σ ≤ 100 m. The large cross section of proton-proton-collisions and th e high luminosity of the accelerator cause relevant background of neutrons and γ s in the muon spectrome- ter. During the next decade a luminosity upgrade [1] to 5 10 34 cm − 2 s − 1 is planned, which will increase the background counting rates consider ably. In this context this work deals with the further development of the existing drift chamber tech- nology to provide the required accuracy of the position meas urement under high background conditions. Two approaches of improving the dri ft tube chambers are described: • In regions of moderate background rates a faster and more lin ear ...

  16. Noise of High Performance Aircraft at Afterburner

    Science.gov (United States)

    2016-05-04

    Mathematics Florida State University Email: tam@math.fsu.edu Grant Monitor Dr. John Spyropoulous Email: John.Spyropoulous@jsf.mil...of equations (1) and (2). Obviously, the computed spectrum is unacceptable. It is overwhelmed by spurious high frequency oscillations. Figure 2...reasoning suggests that we may, as a first approximation, insert a boxcar window function in the integral of equation (4). That is, equation (4) is

  17. High Capacity and Resistance to Additive Noise Audio Steganography Algorithm

    Directory of Open Access Journals (Sweden)

    Haider Ismael Shahadi

    2011-09-01

    Full Text Available Steganography is the art of message hiding in a cover signal without attracting attention. The requirements of the good steganography algorithm are security, capacity, robustness and imperceptibility, all them are contradictory, therefore, satisfying all together is not easy especially in audio cover signal because human auditory system (HAS has high sensitivity to audio modification. In this paper, we proposed a high capacity audio steganography algorithm with good resistance to additive noise. The proposed algorithm is based on wavelet packet transform and blocks matching. It has capacity above 35% of the input audio file size with acceptable signal to noise ratio. Also, it is resistance to additive Gaussian noise to about 25 db. Furthermore, the reconstruction of actual secret messages does not require the original cover audio signal.

  18. Seismic survey in southeastern Socorro Island: Background noise measurements, seismic events, and T phases

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, Raul W [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, D.F. (Mexico); Galindo, Marta [Comprehensive Nuclear-Test-Ban Treaty Organization, IMS, Vienna (Austria); Pacheco, Javier F; Iglesias, Arturo; Teran, Luis F [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, D.F. (Mexico); Barreda, Jose L; Coba, Carlos [Facultad de Ingenieria, Benemerita Universidad Autonoma de Puebla, Puebla (Mexico)

    2005-01-15

    We carried out a seismic survey and installed five portable, broadband seismometers in the southeastern corner of Socorro Island during June 1999. Power spectral densities for all five sites were relatively noisy when compared to reference curves around the world. Power spectral densities remain constant regardless of the time of day, or the day of the week. Cultural noise at the island is very small. Quiet and noisy sites were identified to determine the best location of the T phase station to be installed jointly by the Universidad Nacional Autonoma de Mexico and the Comprehensive Nuclear-Test-Ban Treaty Organization. During the survey six earthquakes were recorded at epicentral distances between 42 km and 2202 km, with magnitudes between 2.8 and 7.0. Two small earthquakes (M{sub c} = 2.8 and 3.3) occurred on the Clarion Fracture Zone. The four largest and more distant earthquakes produced T waves. One T wave from an epicenter near the coast of Guatemala had a duration of about 100 s and a frequency content between 2 and 8 Hz, with maximum amplitude at about 4.75 Hz. The Tehuacan earthquake of June 15, 1999 (M{sub w} = 7.0) produced arrivals of P {yields} T and S {yields} T waves, with energy between 2 Hz and 3.75 Hz. The earthquake occurred inland within the subducted Cocos plate at a depth of 60 km; a significant portion of the path was continental. Seismic P and S waves probably propagated upward in the subducted slab, and were converted to acoustic energy at the continental slope. Total duration of the T phase is close to 500 s and reaches its maximum amplitude about 200 s after the P {yields} T arrival. The T wave contains energy at frequencies between 2 and 10 Hz and reaches its maximum amplitude at about 2.5 Hz. T phases were also recorded from two earthquakes in Guerrero, Mexico and in the Rivera Fracture Zone. [Spanish] En junio de 1999 instalamos cinco sismometros portatiles de banda ancha en el sureste de la Isla Socorro. Se encontro que las densidades

  19. How to coadd images? II. A coaddition image that is optimal for any purpose in the background dominated noise limit

    CERN Document Server

    Zackay, Barak

    2015-01-01

    Image coaddition is one of the most basic operations that astronomers perform. In Paper~I, we presented the optimal ways to coadd images in order to detect faint sources and to perfrom flux measurements under the assumption that the noise is approximately Gaussian. Here, we build on these results and derive from first principles a coaddition technique which is optimal for any hypothesis testing and measurement (e.g., source detection, flux or shape measurements and star/galaxy separation), in the background-noise-dominated case. This method has several important properties. The pixels of the resulting coadd image are uncorrelated. This image preserves all the information (from the original individual images) on all spatial frequencies. Any hypothesis testing or measurement that can be done on all the individual images simultaneously, can be done on the coadded image without any loss of information. The PSF of this image is typically as narrow, or narrower than the PSF of the best image in the ensemble. Moreov...

  20. Noise of High-Performance Aircraft at Afterburner

    Science.gov (United States)

    2015-07-11

    50 ft. from the jet exit by the inverse-square law. The data was acquired at four engine power settings. But only data at 3 power settings are found...8217 ’ ’ ’ ’ 10u f/f- J I 1 I I III, 10’ Figure 10. The two similarity spectra of turbulent mixing noise of high-speed jets . In a previous work ...Vibration, Vol. 352, 103-128, 2015), it was found that when the engine was operating at intermediate power, the jet noise of the engine consisted of

  1. High dimensional matrix estimation with unknown variance of the noise

    CERN Document Server

    Klopp, Olga

    2011-01-01

    We propose a new pivotal method for estimating high-dimensional matrices. Assume that we observe a small set of entries or linear combinations of entries of an unknown matrix $A_0$ corrupted by noise. We propose a new method for estimating $A_0$ which does not rely on the knowledge or an estimation of the standard deviation of the noise $\\sigma$. Our estimator achieves, up to a logarithmic factor, optimal rates of convergence under the Frobenius risk and, thus, has the same prediction performance as previously proposed estimators which rely on the knowledge of $\\sigma$. Our method is based on the solution of a convex optimization problem which makes it computationally attractive.

  2. "EFFECTS OF HIGH-SPEED DRILL NOISE ON DENTISTS’ HEARING "

    Directory of Open Access Journals (Sweden)

    F.Akbakhanzadeh

    1978-11-01

    Full Text Available The study deals with noise problems associated with the use of air-turbine drills in dental practice. Noise level measurements were made on various types of dental handpieces, when operated free running and when used to cut tooth tissue. Hearing acuity tests were also undertaken in 12 randomly selected dental surgeons who have been using these drills for a number of years. The results indicate that although the danger to hearing from high speed drills is small, the possibility of hazardous effects-at least, for susceptible ears- is not excluded.

  3. Fast Impulse Noise Removal from Highly Corrupted Images

    CERN Document Server

    Hosseini, Hossein

    2011-01-01

    In this paper, we suggest a general model for the fixed-valued impulse noise and propose a two-stage method for high density noise suppression while preserving the image details. In the first stage, we apply an iterative impulse detector, exploiting the image entropy, to identify the corrupted pixels and then employ an Adaptive Iterative Mean filter (AIM) to restore them. The filter is adaptive in terms of the number of iterations, which is different for each noisy pixel, according to their Euclidean distance from the nearest uncorrupted pixel. Experimental results show that the AIM filter is fast and outperforms the best existing techniques in both objective and subjective performance measures.

  4. Radiation Response of Emerging High Gain, Low Noise Detectors

    Science.gov (United States)

    Becker, Heidi N.; Farr, William H; Zhu, David Q.

    2007-01-01

    Data illustrating the radiation response of emerging high gain, low noise detectors are presented. Ionizing dose testing of silicon internal discrete avalanche photodiodes, and 51-MeV proton testing of InGaAs/InAlAs avalanche photodiodes operated in Geiger mode are discussed.

  5. Proceedings of the 1987 national conference on noise control engineering: High technology for noise control

    Energy Technology Data Exchange (ETDEWEB)

    Tichy, J.; Hayek, S.

    1987-01-01

    This book consists of nine sections, each containing several papers. The section titles are: Emission: Noise Sources; Physical Phenomena; Noise Control Elements; Vibration: Generation, Transmission, Isolation and Reduction; Immission: Physical Aspects of Environmental Noise; Immission: Effects of Noise; Analysis; Requirements; and Biomedical Uses of Acoustics.

  6. High-Energy Neutron Backgrounds for Underground Dark Matter Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu [Syracuse Univ., NY (United States)

    2016-01-01

    Direct dark matter detection experiments usually have excellent capability to distinguish nuclear recoils, expected interactions with Weakly Interacting Massive Particle (WIMP) dark matter, and electronic recoils, so that they can efficiently reject background events such as gamma-rays and charged particles. However, both WIMPs and neutrons can induce nuclear recoils. Neutrons are then the most crucial background for direct dark matter detection. It is important to understand and account for all sources of neutron backgrounds when claiming a discovery of dark matter detection or reporting limits on the WIMP-nucleon cross section. One type of neutron background that is not well understood is the cosmogenic neutrons from muons interacting with the underground cavern rock and materials surrounding a dark matter detector. The Neutron Multiplicity Meter (NMM) is a water Cherenkov detector capable of measuring the cosmogenic neutron flux at the Soudan Underground Laboratory, which has an overburden of 2090 meters water equivalent. The NMM consists of two 2.2-tonne gadolinium-doped water tanks situated atop a 20-tonne lead target. It detects a high-energy (>~ 50 MeV) neutron via moderation and capture of the multiple secondary neutrons released when the former interacts in the lead target. The multiplicity of secondary neutrons for the high-energy neutron provides a benchmark for comparison to the current Monte Carlo predictions. Combining with the Monte Carlo simulation, the muon-induced high-energy neutron flux above 50 MeV is measured to be (1.3 ± 0.2) ~ 10-9 cm-2s-1, in reasonable agreement with the model prediction. The measured multiplicity spectrum agrees well with that of Monte Carlo simulation for multiplicity below 10, but shows an excess of approximately a factor of three over Monte Carlo prediction for multiplicities ~ 10 - 20. In an effort to reduce neutron backgrounds for the dark matter experiment SuperCDMS SNO- LAB, an active neutron veto was developed

  7. Normal-hearing and hearing-impaired subjects' ability to just follow conversation in competing speech, reversed speech, and noise backgrounds.

    Science.gov (United States)

    Hygge, S; Rönnberg, J; Larsby, B; Arlinger, S

    1992-02-01

    The performance on a conversation-following task by 24 hearing-impaired persons was compared with that of 24 matched controls with normal hearing in the presence of three background noises: (a) speech-spectrum random noise, (b) a male voice, and (c) the male voice played in reverse. The subjects' task was to readjust the sound level of a female voice (signal), every time the signal voice was attenuated, to the subjective level at which it was just possible to understand what was being said. To assess the benefit of lipreading, half of the material was presented audiovisually and half auditorily only. It was predicted that background speech would have a greater masking effect than reversed speech, which would in turn have a lesser masking effect than random noise. It was predicted that hearing-impaired subjects would perform more poorly than the normal-hearing controls in a background of speech. The influence of lipreading was expected to be constant across groups and conditions. The results showed that the hearing-impaired subjects were equally affected by the three background noises and that normal-hearing persons were less affected by the background speech than by noise. The performance of the normal-hearing persons was superior to that of the hearing-impaired subjects. The prediction about lipreading was confirmed. The results were explained in terms of the reduced temporal resolution by the hearing-impaired subjects.

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

    Science.gov (United States)

    Kraft, Toni

    2014-05-01

    measurement precision (i.e. earthquake location), while considering this extremely complex boundary condition. To solve this problem I have developed a high-resolution ambient seismic noise model for Europe. The model is based on land-use data derived from satellite imagery by the EU-project CORINE in a resolution of 100x100m. The the CORINE data consists of several land-use classes, which, besides others, contain: industrial areas, mines, urban fabric, agricultural areas, permanent corps, forests and open spaces. Additionally, open GIS data for highways, and major and minor roads and railway lines were included from the OpenStreetMap project (www.openstreetmap.org). This data was divided into three classes that represent good, intermediate and bad ambient conditions of the corresponding land-use class based on expert judgment. To account for noise propagation away from its source a smoothing operator was applied to individual land-use noise-fields. Finally, the noise-fields were stacked to obtain an European map of ambient noise conditions. A calibration of this map with data of existing seismic stations Europe allowed me to estimate the expected noise level in actual ground motion units for the three ambient noise condition classes of the map. The result is a high-resolution ambient seismic noise map, that allows the network designer to make educated predictions on the expected noise level for arbitrary location in Europe. The ambient noise model was successfully tested in several network optimization projects in Switzerland and surrounding countries and will hopefully be a valuable contribution to improving the data quality of microseismic monitoring networks in Europe.

  9. Ultra High Energy Comic Rays in the Cosmic Microwave Background

    CERN Document Server

    Hwang, W-Y Pauchy

    2011-01-01

    We consider the propagation of ultra high energy cosmic rays (UHECR), for energies greater than E > 10^{14} eV but less than E < 10^{26} eV, in the cosmic medium of the Cosmic Microwave Background (CMB). We find that the CMB plays a pivot role in this energy range. As example, the observed "knee(s)" and the "ankle" could be understood in reasonable terms. What we may observe at energy near 10^{25} eV (W^\\pm bursts or Z^0 bursts) is also briefly discussed.

  10. Passenger comfort on high-speed trains: effect of tunnel noise on the subjective assessment of pressure variations.

    Science.gov (United States)

    Sanok, Sandra; Mendolia, Franco; Wittkowski, Martin; Rooney, Daniel; Putzke, Matthias; Aeschbach, Daniel

    2015-01-01

    When passing through a tunnel, aerodynamic effects on high-speed trains may impair passenger comfort. These variations in atmospheric pressure are accompanied by transient increases in sound pressure level. To date, it is unclear whether the latter influences the perceived discomfort associated with the variations in atmospheric pressure. In a pressure chamber of the DLR-Institute of Aerospace Medicine, 71 participants (M = 28.3 years ± 8.1 SD) rated randomised pressure changes during two conditions according to a crossover design. The pressure changes were presented together with tunnel noise such that the sound pressure level was transiently elevated by either +6 dB (low noise condition) or +12 dB (high noise condition) above background noise level (65 dB(A)). Data were combined with those of a recent study, in which identical pressure changes were presented without tunnel noise (Schwanitz et al., 2013, 'Pressure Variations on a Train - Where is the Threshold to Railway Passenger Discomfort?' Applied Ergonomics 44 (2): 200-209). Exposure-response relationships for the combined data set comprising all three noise conditions show that pressure discomfort increases with the magnitude and speed of the pressure changes but decreases with increasing tunnel noise. Practitioner Summary: In a pressure chamber, we systematically examined how pressure discomfort, as it may be experienced by railway passengers, is affected by the presence of tunnel noise during pressure changes. It is shown that across three conditions (no noise, low noise (+6 dB), high noise (+12 dB)) pressure discomfort decreases with increasing tunnel noise.

  11. High-Temperature Liners for Broadband Noise Reduction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Core noise will become a larger component of engine noise overall, as more efficient design trends of fan and jet noise reduction technologies are implemented. The...

  12. Passive control of rotorcraft high-speed impulsive noise

    Science.gov (United States)

    Szulc, O.; Doerffer, P.; Tejero, F.

    2016-10-01

    A strong, normal shock wave, terminating a local supersonic area located at the tip of a helicopter blade, not only limits the aerodynamic performance, but also constitutes an origin of the High-Speed Impulsive (HSI) noise. The application of a passive control device (a shallow cavity covered by a perforated plate) just beneath the interaction region weakens the compression level, thus reducing the main source of the HSI noise. The numerical investigation based on the URANS approach and Bohning/Doerffer (BD) transpiration law (SPARC code) confirms a large potential of the new method. Two exemplary implementations, adapted to model helicopter rotors tested at NASA Ames facility in transonic conditions: Caradonna-Tung (lifting, transonic hover) and Caradonna-Laub-Tung (non-lifting, high-speed forward flight), demonstrate the possible gains in terms of the reduction of acoustic pressure fluctuations in the near-field of the blade tip. The CFD results are validated against the experimental data obtained for the reference configurations (no control), while the analysis of the passive control arrangement is based on a purely numerical research. The normal shock wave is effectively eliminated by the wall ventilation exerting a positive impact on the generated level of the HSI noise.

  13. Design & Implementation of High Switching & Low Phase Noise Frequency Synthesizer

    Directory of Open Access Journals (Sweden)

    Ali M. N. Hassan

    2006-01-01

    Full Text Available This research describes the design & implementation of frequency synthesizer using single loop Phase lock loop with the following specifications: Frequency range (1.5 – 2.75 GHz,Step size (1 MHz, Switching time 36.4 µs, & phase noise @10 kHz = -92dBc & spurious -100 dBc The development in I.C. technology provide the simplicity in the design of frequency synthesizer because it implements the phase frequency detector(PFD , prescalar & reference divider in single chip. Therefore our system consists of a single chip contains (low phase noise PFD, charge pump, prescalar & reference divider, voltage controlled oscillator , loop filter & reference oscillator. The single chip is used to provide the following properties :•Low power consumptionSmall size, light weight.Flexibility in selecting crystal oscillator frequencies to fit into the system frequency planning.•High reliability.The application of this synthesizer in frequency hopping systems, satellite communications & radar because it has high switching speed ,low phase noise & low spurious level.

  14. High-Tc SQUIDs: Noise and applications

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hsiao-Mei [Univ. of Houston, TX (United States)

    2001-08-01

    A major challenge in the design and operation of high transition temperature (Tc ) Superconducting Quantum Interference Devices (SQUIDs) is their potential to exhibit substantially higher levels of noise at low frequency f when exposed to earth’s magnetic field. To investigate this problem, we studied the noise of high-Tc SQUIDs, directly coupled magnetometers and multilayer magnetometers in both static and changing magnetic fields. The directly coupled magnetometer consists of a dc SQUID connected to a large area pickup loop in parallel. The multilayer magnetometer involves a multiturn flux transformer inductively coupled to a dc SQUID on a separate substrate. All the devices are made of thin films of the high-Tc superconductor YBa2Cu3O7-δ, patterned into 4 μm linewidths. After cooling in a magnetic field, the devices showed no increase in 1/f noise for fields up to threshold values well above the earth’s magnetic field. The devices were also cooled in a magnetic field that was subsequently turned off. The 1/f noise of bare SQUIDs was unchanged for fields up to 12 μT. The addition of the flux transformer containing flux dams increased the sensitivity to magnetic field by a factor of 43 while reducing the threshold field only moderately, to 5 μT. This result implies that the multilayer magnetometer can be rotated in the earth’s magnetic field through an angle of up to 26o without increasing the low frequency noise. The results of these studies were incorporated into a 5-channel high-Tc magnetocardiography system involving two first-derivative SQUID gradiometers and three reference SQUIDs. Each planar gradiometer consists of a directly coupled SQUID magnetometer inductively coupled to the smaller coil of an asymmetric, two-loop flux transformer. The reference SQUIDs are patterned into 4 μm lines. The outputs of the five channels were subtracted in software to form a second-derivative gradiometer. Its

  15. An investigation of community noise in high-rise residential environments.

    Science.gov (United States)

    Alam, Sheikh Mahbub; Eang, Lee Siew; Tan, Alan; Tiong, Tan Sze

    2010-06-01

    High-rise dwellers in Singapore are often subjected to several community noise sources in close proximity. These include food center, children playground, soccer playground, basketball playground, waste disposal truck, etc. A scientific and reliable approach is required for evaluation of the community noise and its impact on high-rise dwellers. A comprehensive noise survey by a cluster sampling technique, conducted among 522 households in five residential towns in Singapore, showed that community noise was one of the prime sources of noise in a high-rise residential environment. From a subjective noise survey, undertaken concurrent with objective noise measurements, a mean outdoor noise level of 59 dBA was established as an acceptable noise level in the indoor environment. To investigate the level of noise exposure from different community noise sources, software modeling and simulations were carried out. The predicted results were validated with field measured data at five 16 story residential buildings. Analysis of noise exposure data showed that except for waste disposal truck, noise exposure due to other community noise sources (building distance of 15 m) were within the established acceptable noise level. A factor analysis of the survey data identified the key factors related to the disturbance due to community noise sources.

  16. Noise Simulations of the High-Lift Common Research Model

    Science.gov (United States)

    Lockard, David P.; Choudhari, Meelan M.; Vatsa, Veer N.; O'Connell, Matthew D.; Duda, Benjamin; Fares, Ehab

    2017-01-01

    The PowerFLOW(TradeMark) code has been used to perform numerical simulations of the high-lift version of the Common Research Model (HL-CRM) that will be used for experimental testing of airframe noise. Time-averaged surface pressure results from PowerFLOW(TradeMark) are found to be in reasonable agreement with those from steady-state computations using FUN3D. Surface pressure fluctuations are highest around the slat break and nacelle/pylon region, and synthetic array beamforming results also indicate that this region is the dominant noise source on the model. The gap between the slat and pylon on the HL-CRM is not realistic for modern aircraft, and most nacelles include a chine that is absent in the baseline model. To account for those effects, additional simulations were completed with a chine and with the slat extended into the pylon. The case with the chine was nearly identical to the baseline, and the slat extension resulted in higher surface pressure fluctuations but slightly reduced radiated noise. The full-span slat geometry without the nacelle/pylon was also simulated and found to be around 10 dB quieter than the baseline over almost the entire frequency range. The current simulations are still considered preliminary as changes in the radiated acoustics are still being observed with grid refinement, and additional simulations with finer grids are planned.

  17. Background field coils for the High Field Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Zbasnik, J.P.; Cornish, D.N.; Scanlan, R.M.; Jewell, A.M.; Leber, R.L.; Rosdahl, A.R.; Chaplin, M.R.

    1980-09-22

    The High Field Test Facility (HFTF), presently under construction at LLNL, is a set of superconducting coils that will be used to test 1-m-o.d. coils of prototype conductors for fusion magnets in fields up to 12 T. The facility consists of two concentric sets of coils; the outer set is a stack of Nb-Ti solenoids, and the inner set is a pair of solenoids made of cryogenically-stabilized, multifilamentary Nb/sub 3/Sn superconductor, developed for use in mirror-fusion magnets. The HFTF system is designed to be parted along the midplane to allow high-field conductors, under development for Tokamak fusion machines, to be inserted and tested. The background field coils were wound pancake-fashion, with cold-welded joints at both the inner and outer diameters. Turn-to-turn insulation was fabricated at LLNL from epoxy-fiberglass strip. The coils were assembled and tested in our 2-m-diam cryostat to verify their operation.

  18. High signal-to-noise ratio quantum well bolometer materials

    Science.gov (United States)

    Wissmar, Stanley; Höglund, Linda; Andersson, Jan; Vieider, Christian; Savage, Susan; Ericsson, Per

    2006-09-01

    Novel single crystalline high-performance temperature sensing materials (quantum well structures) have been developed for the manufacturing of uncooled infrared bolometers. SiGe/Si and AlGaAs/GaAs quantum wells are grown epitaxially on standard Si and GaAs substrates respectively. The former use holes as charge carriers utilizing the discontinuities in the valence band structure, whereas the latter operate in a similar manner with electrons in the conduction band. By optimizing parameters such as the barrier height (by variation of the germanium/aluminium content respectively) and the fermi level E f (by variation of the quantum well width and doping level) these materials provide the potential to engineer layer structures with a very high temperature coefficient of resistance, TCR, as compared with conventional thin film materials such as vanadium oxide and amorphous silicon. In addition, the high quality crystalline material promises very low 1/f-noise characteristics promoting an outstanding signal to noise ratio and well defined and uniform material properties, A comparison between the two (SiGe/Si and AlGaAs/GaAs) quantum well structures and their fundamental theoretical limits are discussed and compared to experimental results. A TCR of 2.0%/K and 4.5%/K have been obtained experimentally for SiGe/Si and AlGaAs/GaAs respectively. The noise level for both materials is measured as being several orders of magnitude lower than that of a-Si and VOx. These uncooled thermistor materials can be hybridized with read out circuits by using conventional flip-chip assembly or wafer level adhesion bonding. The increased bolometer performance so obtained can either be exploited for increasing the imaging system performance, i. e. obtaining a low NETD, or to reduce the vacuum packaging requirements for low cost applications (e.g. automotive).

  19. Radioactivity in the groundwater of a high background radiation area.

    Science.gov (United States)

    Shabana, E I; Kinsara, A A

    2014-11-01

    Natural radioactivity was measured in groundwater samples collected from 37 wells scattered in an inhabited area of high natural background radiation, in a purpose of radiation protection. The study area is adjacent to Aja heights of granitic composition in Hail province, Saudi Arabia. Initial screening for gross α and gross β activities showed levels exceeded the national regulation limits set out for gross α and gross β activities in drinking water. The gross α activity ranged from 0.17 to 5.41 Bq L(-)(1) with an average value of 2.15 Bq L(-)(1), whereas gross β activity ranged from 0.48 to 5.16 Bq L(-)(1), with an average value of 2.60 Bq L(-)(1). The detail analyses indicated that the groundwater of this province is contaminated with uranium and radium ((226)Ra and (228)Ra). The average activity concentrations of (238)U, (234)U, (226)Ra and (228)Ra were 0.40, 0.77, 0.29 and 0.46 Bq L(-)(1), respectively. The higher uranium content was found in the samples of granitic aquifers, whereas the higher radium content was found in the samples of sandstone aquifers. Based on the obtained results, mechanism of leaching of the predominant radionuclides has been discussed in detail.

  20. A high resolution, low background fast neutron spectrometer

    CERN Document Server

    Abdurashitov, J N; Kalikhov, A V; Matushko, V L; Shikhin, A A; Yants, V E; Zaborskaia, O S; Adams, J M; Nico, J S; Thompson, A K

    2002-01-01

    We discuss the possibility to create a spectrometer of full absorption based on liquid scintillator doped with enriched sup 6 Li. Of specific interest, the spectrometer will have energy resolution estimated to lie in the range 5-10% for 14 MeV neutrons. It will be sensitive to fluxes from 10 sup - sup 4 to 10 sup 6 cm sup - sup 2 s sup - sup 1 above a threshold of 1 MeV in a gamma-background of up to 10 sup 4 s sup - sup 1. The detector's efficiency will be determined by the volume of the scintillator only (approx 3 l) and is estimated to be 0.2-10%. The main reason for the poor resolution of an organic scintillator based spectrometer of full absorption is a non-linear light-yield of the scintillator for recoil protons. The neutron energy is occasionally distributed among recoil protons, and due to non-linear light-yield the total amount of light from all recoil protons ambiguously determines the initial neutron energy. The high-energy resolution will be achieved by compensation of the non-linear light-yield ...

  1. Detecting high-$z$ galaxies in the Near Infrared Background

    CERN Document Server

    Yue, Bin; Helgason, Kári

    2015-01-01

    Emission from high-$z$ galaxies must unquestionably contribute to the Near-InfraRed Background (NIRB). However, this contribution has so far proven difficult to isolate even after subtracting resolved galaxies to deep levels. Remaining NIRB fluctuations are dominated by unresolved low-redshift galaxies on small angular scales, and by an unidentified component of unclear origin on large scales ($\\approx 1000"$). In this paper, by analyzing mock maps generated from semi-numerical simulations and empirically determined $L_{\\rm UV} - M_{\\rm h}$ relations, we find that fluctuations associated with galaxies at $5 < z < 10$ amount to several percent of the unresolved NIRB flux. We investigate the properties of this component for different survey areas and limiting magnitudes. In all cases, we show that this signal can be efficiently, and most easily at small angular scales, isolated by cross-correlating the source-subtracted NIRB with Lyman Break Galaxies (LBGs) detected in the same field by {\\tt HST} surveys....

  2. Effects of high combustion chamber pressure on rocket noise environment

    Science.gov (United States)

    Pao, S. P.

    1972-01-01

    The acoustical environment for a high combustion chamber pressure engine was examined in detail, using both conventional and advanced theoretical analysis. The influence of elevated chamber pressure on the rocket noise environment was established, based on increase in exit velocity and flame temperature, and changes in basic engine dimensions. Compared to large rocket engines, the overall sound power level is found to be 1.5 dB higher, if the thrust is the same. The peak Strouhal number shifted about one octave lower to a value near 0.01. Data on apparent sound source location and directivity patterns are also presented.

  3. Combined effect of noise and vibration produced by high-speed trains on annoyance in buildings.

    Science.gov (United States)

    Lee, Pyoung Jik; Griffin, Michael J

    2013-04-01

    The effects of noise and vibration on annoyance in buildings during the passage of a nearby high-speed train have been investigated in a laboratory experiment with recorded train noise and 20 Hz vibration. The noises included the effects of two types of façade: windows-open and windows-closed. Subjects were exposed to six levels of noise and six magnitudes of vibration, and asked to rate annoyance using an 11-point numerical scale. The experiment consisted of four sessions: (1) evaluation of noise annoyance in the absence of vibration, (2) evaluation of total annoyance from simultaneous noise and vibration, (3) evaluation of noise annoyance in the presence of vibration, and (4) evaluation of vibration annoyance in the absence of noise. The results show that vibration did not influence ratings of noise annoyance, but that total annoyance caused by combined noise and vibration was considerably greater than the annoyance caused by noise alone. The noise annoyance and the total annoyance caused by combined noise and vibration were associated with subject self-ratings of noise sensitivity. Two classical models of total annoyance due to combined noise sources (maximum of the single source annoyance or the integration of individual annoyance ratings) provided useful predictions of the total annoyance caused by simultaneous noise and vibration.

  4. Reducing the Effects of Background Noise during Auditory Functional Magnetic Resonance Imaging of Speech Processing: Qualitative and Quantitative Comparisons between Two Image Acquisition Schemes and Noise Cancellation

    Science.gov (United States)

    Blackman, Graham A.; Hall, Deborah A.

    2011-01-01

    Purpose: The intense sound generated during functional magnetic resonance imaging (fMRI) complicates studies of speech and hearing. This experiment evaluated the benefits of using active noise cancellation (ANC), which attenuates the level of the scanner sound at the participant's ear by up to 35 dB around the peak at 600 Hz. Method: Speech and…

  5. Reducing the Effects of Background Noise during Auditory Functional Magnetic Resonance Imaging of Speech Processing: Qualitative and Quantitative Comparisons between Two Image Acquisition Schemes and Noise Cancellation

    Science.gov (United States)

    Blackman, Graham A.; Hall, Deborah A.

    2011-01-01

    Purpose: The intense sound generated during functional magnetic resonance imaging (fMRI) complicates studies of speech and hearing. This experiment evaluated the benefits of using active noise cancellation (ANC), which attenuates the level of the scanner sound at the participant's ear by up to 35 dB around the peak at 600 Hz. Method: Speech and…

  6. Passive ultrasonics using sub-Nyquist sampling of high-frequency thermal-mechanical noise.

    Science.gov (United States)

    Sabra, Karim G; Romberg, Justin; Lani, Shane; Degertekin, F Levent

    2014-06-01

    Monolithic integration of capacitive micromachined ultrasonic transducer arrays with low noise complementary metal oxide semiconductor electronics minimizes interconnect parasitics thus allowing the measurement of thermal-mechanical (TM) noise. This enables passive ultrasonics based on cross-correlations of diffuse TM noise to extract coherent ultrasonic waves propagating between receivers. However, synchronous recording of high-frequency TM noise puts stringent requirements on the analog to digital converter's sampling rate. To alleviate this restriction, high-frequency TM noise cross-correlations (12-25 MHz) were estimated instead using compressed measurements of TM noise which could be digitized at a sampling frequency lower than the Nyquist frequency.

  7. High-Fidelity Simulation of Turbofan Noise Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Broadband fan noise ? closely tied to turbulent flow on and around the fan blades ? represents a key challenge to the noise reduction community due to the...

  8. High Precision Cosmology with the Cosmic Background Radiation

    Science.gov (United States)

    Farhang, Marzieh

    In this thesis we investigate the two cosmic epochs of inflation and recombination, through their imprints on the temperature and polarization anisotropies of the cosmic microwave background radiation. To probe the early universe we develop a map-based maximum-likelihood estimator to measure the amplitude of inflation-induced gravity waves, parametrized by r, from the cosmic microwave background (CMB) polarization maps. Being optimal by construction, the estimator avoids E-B mixing, a possible source of contamination in the tiny B-mode detection, the target of many current and near future CMB experiments. We explore the leakage from the E- to the B-mode of polarization by using this estimator to study the linear response of the B-mode signal at different scales to variations in the E- mode power. Similarly, for various observational cases, we probe the dependence of r measurement on the signal from different scales of E and B polarization. The estimator is used to make forecasts for Spider-like and Planck-like experimental specifications and to investigate the sky-coverage optimization of the Spider-like case. We compare the forecast errors on r to the results from a similar multipole-based estimator which, by ignoring the mode-mixing, sets a lower limit on the achievable error on r. We find that an experiment with Spider-like specifications with fsky ˜ 0:02--0:2 could place a 2sigma r ≈ 0:014 bound (˜ 95% CL), which rises to 0:02 with an ℓ-dependent foreground residual left over from an assumed efficient component separation. For the Planck-like survey, a Galaxy-masked ( fsky = 0:75) sky would give 2sigmar ≈ 0:015, rising to ≈ 0:05 with the foreground residuals. We also use a novel information-based framework to compare how different generations of CMB experiments reveal information about the early universe, through their measurements of r. We also probe the epoch of recombination by investigating possible fluctuations in the free electron fraction Xe

  9. Similarity spectra analysis of high-performance jet aircraft noise.

    Science.gov (United States)

    Neilsen, Tracianne B; Gee, Kent L; Wall, Alan T; James, Michael M

    2013-04-01

    Noise measured in the vicinity of an F-22A Raptor has been compared to similarity spectra found previously to represent mixing noise from large-scale and fine-scale turbulent structures in laboratory-scale jet plumes. Comparisons have been made for three engine conditions using ground-based sideline microphones, which covered a large angular aperture. Even though the nozzle geometry is complex and the jet is nonideally expanded, the similarity spectra do agree with large portions of the measured spectra. Toward the sideline, the fine-scale similarity spectrum is used, while the large-scale similarity spectrum provides a good fit to the area of maximum radiation. Combinations of the two similarity spectra are shown to match the data in between those regions. Surprisingly, a combination of the two is also shown to match the data at the farthest aft angle. However, at high frequencies the degree of congruity between the similarity and the measured spectra changes with engine condition and angle. At the higher engine conditions, there is a systematically shallower measured high-frequency slope, with the largest discrepancy occurring in the regions of maximum radiation.

  10. Anomalously high noise levels in a fibre Bragg grating semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Kurnosov, V D; Kurnosov, K V [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2015-01-31

    Taking into account gain nonlinearity allows one to obtain anomalously high noise levels in a fibre Bragg grating laser diode. This paper examines the effect of the gain nonlinearity due to spectral hole burning on noise characteristics. (lasers)

  11. Failing to Get the Gist of What’s Being Said: Background Noise Impairs Higher Order Cognitive Processing

    Directory of Open Access Journals (Sweden)

    John Everett Marsh

    2015-05-01

    Full Text Available A dynamic interplay is known to exist between auditory processing and human cognition. For example, prior investigations of speech-in-noise have revealed there is more to learning than just listening: Even if all words within a spoken list correctly heard in noise, later memory for those words is typically impoverished. At such low signal-to-noise ratios when listeners could identify words, those participants could not necessarily remember those words. These investigations supported a view that there is a gap between the intelligibility of speech and memory for that speech. Here, the notion was that this gap between speech intelligibility and memorability is a function of the extent to which the spoken message seizes limited immediate memory resources (e.g., Kjellberg, Ljung, & Hallman, 2008. Accordingly, the more difficult the processing of the spoken message, the less resources are available for elaboration, storage, and recall of that spoken material. However, it was not previously known how increasing that difficulty affected the memory processing of semantically rich spoken material. This investigation showed that noise impairs higher levels of cognitive analysis. A variant of the Deese-Roediger-McDermott procedure that encourages semantic elaborative processes was deployed. On each trial, participants listened to a 36-item list comprising 12 words blocked by each of 3 different themes. Each of those 12 words (e.g., bed, tired, snore… was associated with a critical lure theme word that was not presented (e.g., sleep. Word lists were either presented without noise or at a signal-to-noise ratio of 5 decibels upon an A-weighting. Noise reduced false recall of the critical words, and decreased the semantic clustering of recall. Theoretical and practical implications are discussed.

  12. Noise reduction in muon tomography for detecting high density objects

    CERN Document Server

    Benettoni, M; Bonomi, G; Calvagno, G; Calvini, P; Checchia, P; Cortelazzo, G; Cossutta, L; Donzella, A; Furlan, M; Gonella, F; Pegoraro, M; Garola, A Rigoni; Ronchese, P; Squarcia, S; Subieta, M; Vanini, S; Viesti, G; Zanuttigh, P; Zenoni, A; Zumerle, G

    2013-01-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. A new and innovative method is presented in this paper to handle the density fluctuations (noise) of reconstructed images, that are a known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect in short times high density materials, such as lead, when surrounded by light or medium density material. A comparison with algorithms published in literature is also presented.

  13. Noise reduction in muon tomography for detecting high density objects

    Science.gov (United States)

    Benettoni, M.; Bettella, G.; Bonomi, G.; Calvagno, G.; Calvini, P.; Checchia, P.; Cortelazzo, G.; Cossutta, L.; Donzella, A.; Furlan, M.; Gonella, F.; Pegoraro, M.; Rigoni Garola, A.; Ronchese, P.; Squarcia, S.; Subieta, M.; Vanini, S.; Viesti, G.; Zanuttigh, P.; Zenoni, A.; Zumerle, G.

    2013-12-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented.

  14. Nature of the Background Ultraviolet Radiation Field at High Redshifts

    Indian Academy of Sciences (India)

    Archana Samantaray; Pushpa Khare

    2000-06-01

    We have tried to determine the flux of the ultraviolet background radiation field from the column density ratios of various ions in several absorption systems observed in the spectra of QSOs. We find that in most cases the flux is considerably higher than what has been estimated to be contributed by the AGNs. The excess flux could originate locally in hot stars. In a few cases we have been able to show that such galactic flux can only contribute a part of the total required flux. The results suggest that the background gets a significant contribution from an unseen QSO population.

  15. Parametric merging of MEG and fMRI reveals spatiotemporal differences in cortical processing of spoken words and environmental sounds in background noise.

    Science.gov (United States)

    Renvall, Hanna; Formisano, Elia; Parviainen, Tiina; Bonte, Milene; Vihla, Minna; Salmelin, Riitta

    2012-01-01

    There is an increasing interest to integrate electrophysiological and hemodynamic measures for characterizing spatial and temporal aspects of cortical processing. However, an informative combination of responses that have markedly different sensitivities to the underlying neural activity is not straightforward, especially in complex cognitive tasks. Here, we used parametric stimulus manipulation in magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) recordings on the same subjects, to study effects of noise on processing of spoken words and environmental sounds. The added noise influenced MEG response strengths in the bilateral supratemporal auditory cortex, at different times for the different stimulus types. Specifically for spoken words, the effect of noise on the electrophysiological response was remarkably nonlinear. Therefore, we used the single-subject MEG responses to construct parametrization for fMRI data analysis and obtained notably higher sensitivity than with conventional stimulus-based parametrization. fMRI results showed that partly different temporal areas were involved in noise-sensitive processing of words and environmental sounds. These results indicate that cortical processing of sounds in background noise is stimulus specific in both timing and location and provide a new functionally meaningful platform for combining information obtained with electrophysiological and hemodynamic measures of brain function.

  16. Adaptive iterated function systems filter for images highly corrupted with fixed - Value impulse noise

    Science.gov (United States)

    Shanmugavadivu, P.; Eliahim Jeevaraj, P. S.

    2014-06-01

    The Adaptive Iterated Functions Systems (AIFS) Filter presented in this paper has an outstanding potential to attenuate the fixed-value impulse noise in images. This filter has two distinct phases namely noise detection and noise correction which uses Measure of Statistics and Iterated Function Systems (IFS) respectively. The performance of AIFS filter is assessed by three metrics namely, Peak Signal-to-Noise Ratio (PSNR), Mean Structural Similarity Index Matrix (MSSIM) and Human Visual Perception (HVP). The quantitative measures PSNR and MSSIM endorse the merit of this filter in terms of degree of noise suppression and details/edge preservation respectively, in comparison with the high performing filters reported in the recent literature. The qualitative measure HVP confirms the noise suppression ability of the devised filter. This computationally simple noise filter broadly finds application wherein the images are highly degraded by fixed-value impulse noise.

  17. A HIGH STABILITY, LOW NOISE RF DISTRIBUTION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, Dorel

    2002-08-20

    Next generation linear colliders require high stability, low noise distribution of RF phase and timing signals. We describe a fiber-optics system that transmits phase at 357MHz, at a 1500nm wavelength, over a distance of 15 kilometers. Phase length errors in the transmission fiber are measured using the phase of the signal reflected from the fiber end. Corrections are performed by controlling the temperature of a 6-kilometer fiber spool placed in series with the main transmission fiber. This system has demonstrated a phase stability better than 10 femtoseconds per degree C, per kilometer, an improvement of a factor of >2000 relative to un-stabilized fiber. This system uses standard low cost telecom fiber and components.

  18. Noise calculation model and analysis of high-gain readout circuits for CMOS image sensors

    Science.gov (United States)

    Kawahito, Shoji; Itoh, Shinya

    2008-02-01

    A thermal noise calculation model of high-gain switched-capacitor column noise cancellers for CMOS image sensors is presented. In the high-gain noise canceller with a single noise cancelling stage, the reset noise of the readout circuits dominates the noise at high gain. Using the double-stage architecture using a switched-capacitor gain stage and a sample-and-hold stage using two sampling capacitors, the reset noise of the gain stage can be cancelled. The resulting input referred thermal noise power of high-gain double-stage switched-capacitor noise canceller is revealed to be proportional to (g_a/g_s)/GC_L where g_a, G and C_L are the transconductance, gain and output capacitance of the amplifier, respectively, and g_s is the output conductance of an in-pixel source follower. An important contribution of the proposed noise calculation formula is the inclusion of the influence of the transconductance ratio of the amplifier to that of the source follower. For low-noise design, it is important that the transconductance of the amplifier used in the noise canceller is minimized under the condition of meeting the required response time of the switched capacitor amplifier which is inversely proportional to the cutoff angular frequency.

  19. Adaptive Cancellation of Background Noise of Fiber Optic Vector Sensor System%光纤矢量水听器系统本底噪声的自适应抵消

    Institute of Scientific and Technical Information of China (English)

    吴艳群; 罗洪; 胡正良; 熊水东; 胡永明

    2011-01-01

    Background noise is one of the most important properties for the interferometric fiber optic vector sensor systems, which limits the systems' application of the detection of the long distance and low frequency targets. To reduce the background noise, a noise suppression scheme based on an adaptive noise canceller is proposed. A pressure insensitive reference fiber optic Michelson interferometer is added as a reference sensor, whose structural parameters are the same as those of the sensing fiber optic interferometers. Then the background noises of the pressure or acceleration signal, which are highly correlated with the reference signal, can be cancelled by the normalized least root mean square error algorithm. The results of a lake trial show that the scheme can effectively reduce both the background noise of the pressure and the accelerometer channels, which can suppress the 50 Hz multiples of the electromagnetic interference by 15~25 dB, and the flat phase noise above 500 Hz by about 3 dB.%本底噪声是制约干涉型光纤矢量水听器系统在低频远距离目标探测领域中应用的重要因素之一.为降低系统的本底噪声,提出了一种基于自适应噪声抵消的降噪方法.在光学系统中增加一个与传感迈克耳孙干涉仪结构参数相等的对声压不敏感的参考干涉仪作为参考通道,以获得由光源与电路等共同噪声源引入到各干涉仪的高相关噪声.然后,使用归一化均方根误差的自适应算法分别对声压及加速度信号中与参考信号高相关的噪声部分进行抵消.湖试数据的分析结果表明,该方案能够有效降低系统本底噪声,其中对电磁干扰带来的50 Hz倍频信号的抑制能力高达15~25 dB,对500 Hz以上的平坦噪声谱的抑制为3 dB左右.

  20. The Galker test of speech reception in noise; associations with background variables, middle ear status, hearing, and language in Danish preschool children.

    Science.gov (United States)

    Lauritsen, Maj-Britt Glenn; Söderström, Margareta; Kreiner, Svend; Dørup, Jens; Lous, Jørgen

    2016-01-01

    We tested "the Galker test", a speech reception in noise test developed for primary care for Danish preschool children, to explore if the children's ability to hear and understand speech was associated with gender, age, middle ear status, and the level of background noise. The Galker test is a 35-item audio-visual, computerized word discrimination test in background noise. Included were 370 normally developed children attending day care center. The children were examined with the Galker test, tympanometry, audiometry, and the Reynell test of verbal comprehension. Parents and daycare teachers completed questionnaires on the children's ability to hear and understand speech. As most of the variables were not assessed using interval scales, non-parametric statistics (Goodman-Kruskal's gamma) were used for analyzing associations with the Galker test score. For comparisons, analysis of variance (ANOVA) was used. Interrelations were adjusted for using a non-parametric graphic model. In unadjusted analyses, the Galker test was associated with gender, age group, language development (Reynell revised scale), audiometry, and tympanometry. The Galker score was also associated with the parents' and day care teachers' reports on the children's vocabulary, sentence construction, and pronunciation. Type B tympanograms were associated with a mean hearing 5-6dB below that of than type A, C1, or C2. In the graphic analysis, Galker scores were closely and significantly related to Reynell test scores (Gamma (G)=0.35), the children's age group (G=0.33), and the day care teachers' assessment of the children's vocabulary (G=0.26). The Galker test of speech reception in noise appears promising as an easy and quick tool for evaluating preschool children's understanding of spoken words in noise, and it correlated well with the day care teachers' reports and less with the parents' reports. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. Effect of low light and high noise on behavioural activity, physiological indicators of stress and production in laying hens.

    Science.gov (United States)

    O'connor, E A; Parker, M O; Davey, E L; Grist, H; Owen, R C; Szladovits, B; Demmers, T G M; Wathes, C M; Abeyesinghe, S M

    2011-12-01

    1. Commercial laying hens are commonly housed in noisy and dim environments, yet relatively little is known about whether these conditions, particularly in combination, have any effect on welfare or egg production. 2. The study was designed to investigate whether chronic exposure to continuous noise (60 dB(A) vs. 80 dB(A)) and/or light intensity (150 lux vs. 5 lux) during the critical period of coming into lay (16-24 weeks of age) influenced behaviour (activity, resting and feather maintenance), physiological stress (plasma corticosterone and heterophil to lymphocyte ratio) and production (number and weight of eggs laid) in laying hens. 3. Hens in the low light pens were less active and preened and dust-bathed more than those housed in 150 lux; hens in the high noise pens rested more frequently than those in quieter pens. 4. There was no evidence that chronic exposure to low light or high noise caused appreciable physiological stress but egg production was affected by these conditions. Hens kept in pens with low light or high noise laid fewer eggs per day than those kept in high light or low noise pens. These effects were additive, so that the fewest eggs were laid by hens subject to both low light and high noise. 5. These results show that low light intensity and continual high background noise have a detrimental effect on egg production in the early laying phase as well as influencing the time allocated to different behaviours. However there was no strong evidence for a physiological stress response to either of these conditions or their combination.

  2. 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

  3. Comparison of Two Dose-response Relationship of Noise Exposure Evaluation Results with High Frequency Hearing Loss

    Institute of Scientific and Technical Information of China (English)

    Hua Zhang; Nan Li; Qiu-Ling Yang; Wei Qiu; Liang-Liang Zhu; Li-Yuan Tao; Robert I Davis

    2015-01-01

    Background:Complex noise and its relation to hearing loss are difficult to measure and evaluate.In complex noise measurement,individual exposure results may not accurately represent lifetime noise exposure.Thus,the mean LAeq,8 h values of individuals in the same workgroup were also used to represent LAeq,8h in our study.Our study aimed to explore whether the mean exposure levels of workers in the same workgroup represented real noise exposure better than individual exposure levels did.Methods:A cross-sectional study was conducted to establish a model for cumulative noise exposure (CNE) and hearing loss in 205 occupational noise-exposed workers who were recruited from two large automobile manufacturers in China.We used a personal noise dosimeter and a questionnaire to determine the workers' occupational noise exposure levels and exposure times,respectively.A qualified audiologist used standardized audiometric procedures to assess hearing acuity after at least 16 h of noise avoidance.Results:We observed that 88.3% of workers were exposed to more than 85 dB(A) of occupational noise (mean:89.3 ± 4.2 dB(A)).The personal CNE (CNEp) and workgroup CNE (CNEg) were 100.5 ± 4.7 dB(A) and 100.5 ± 2.9 dB(A),respectively.In the binary logistic regression analysis,we established a regression model with high-frequency hearing loss as the dependent variable and CNE as the independent variable.The Wald value was 5.014 with CNEp as the independent variable and 8.653 with CNEg as the independent variable.Furthermore,we found that the figure for CNEg was more similar to the stationary noise reference than CNEp was.The CNEg model was better than the CNEp model.In this circumstance,we can measure some subjects instead of the whole workgroup and save manpower.Conclusions:In a complex noise environment,the measurements of average noise exposure level of the workgroup can improve the accuracy and save manpower.

  4. Comparison of Two Dose-response Relationship of Noise Exposure Evaluation Results with High Frequency Hearing Loss

    Directory of Open Access Journals (Sweden)

    Hua Zhang

    2015-01-01

    Full Text Available Background: Complex noise and its relation to hearing loss are difficult to measure and evaluate. In complex noise measurement, individual exposure results may not accurately represent lifetime noise exposure. Thus, the mean L Aeq,8 h values of individuals in the same workgroup were also used to represent L Aeq,8 h in our study. Our study aimed to explore whether the mean exposure levels of workers in the same workgroup represented real noise exposure better than individual exposure levels did. Methods: A cross-sectional study was conducted to establish a model for cumulative noise exposure (CNE and hearing loss in 205 occupational noise-exposed workers who were recruited from two large automobile manufacturers in China. We used a personal noise dosimeter and a questionnaire to determine the workers′ occupational noise exposure levels and exposure times, respectively. A qualified audiologist used standardized audiometric procedures to assess hearing acuity after at least 16 h of noise avoidance. Results: We observed that 88.3% of workers were exposed to more than 85 dB(A of occupational noise (mean: 89.3 ± 4.2 dB(A. The personal CNE (CNEp and workgroup CNE (CNEg were 100.5 ± 4.7 dB(A and 100.5 ± 2.9 dB(A, respectively. In the binary logistic regression analysis, we established a regression model with high-frequency hearing loss as the dependent variable and CNE as the independent variable. The Wald value was 5.014 with CNEp as the independent variable and 8.653 with CNEg as the independent variable. Furthermore, we found that the figure for CNEg was more similar to the stationary noise reference than CNEp was. The CNEg model was better than the CNEp model. In this circumstance, we can measure some subjects instead of the whole workgroup and save manpower. Conclusions: In a complex noise environment, the measurements of average noise exposure level of the workgroup can improve the accuracy and save manpower.

  5. Large Fluctuations in the High-Redshift Metagalactic Ionizing Background

    CERN Document Server

    D'Aloisio, Anson; Davies, Frederick B; Furlanetto, Steven R

    2016-01-01

    Recent observations have shown that the scatter in opacities among coeval segments of the Lyman-alpha forest increases rapidly at z > 5. In this paper, we assess whether the large scatter can be explained by fluctuations in the ionizing background in the post-reionization intergalactic medium. We find that matching the observed scatter at z ~ 5.5 requires a short spatially averaged mean free path of 3 shorter than direct measurements at z ~ 5.2. We argue that such rapid evolution in the mean free path is difficult to reconcile with our measurements of the global H I photoionization rate, which stay approximately constant over the interval z ~ 4.8 - 5.5. However, we also show that measurements of the mean free path at z > 5 are likely biased towards higher values by the quasar proximity effect. This bias can reconcile the short values of the mean free path that are required to explain the large scatter in opacities. We discuss the implications of this scenario for cosmological reionization. Finally, we invest...

  6. Quantum 1/f Noise in High Technology Applications Including Ultrasmall Structures and Devices

    Science.gov (United States)

    1992-07-14

    Noise in Physical Systems and III Int. Conf. on 1/f Noise, Montpellier, May 17-20, 1983, V.M. Savelli, G. Lecoy and J.P. Nougier Editors, North...Handel, ’Any Particle Represented by a Coherent State Exhibits 1/f Noise" in "Noise in Physical Systems and 1/f Noise’, edited by M. Savelli, G. Lecoy and...218-225. [491 M.B. Bloch, J.C. Ho, C.S. Stone , A. Syed and F.L Walls, "Stability of High Quality Quartz Crystal Oscillators: an Update", Proc. 43rd

  7. High Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Noise mitigation for subsonic transports is a continuing high priority, and recent work has identified successful exhaust mixing enhancement devices that have...

  8. High Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Noise mitigation for subsonic transports is a continuing high priority, and recent work has identified successful exhaust mixing enhancement devices (chevrons) that...

  9. Noise Reduction in High-Throughput Gene Perturbation Screens

    Science.gov (United States)

    Motivation: Accurate interpretation of perturbation screens is essential for a successful functional investigation. However, the screened phenotypes are often distorted by noise, and their analysis requires specialized statistical analysis tools. The number and scope of statistical methods available...

  10. On the (In)Efficiency of the Cross-Correlation Statistic for Gravitational Wave Stochastic Background Signals with Non-Gaussian Noise and Heterogeneous Detector Sensitivities

    CERN Document Server

    Lionel, Martellini

    2015-01-01

    Under standard assumptions including stationary and serially uncorrelated Gaussian gravitational wave stochastic background signal and noise distributions, as well as homogenous detector sensitivities, the standard cross-correlation detection statistic is known to be optimal in the sense of minimizing the probability of a false dismissal at a fixed value of the probability of a false alarm. The focus of this paper is to analyze the comparative efficiency of this statistic, versus a simple alternative statistic obtained by cross-correlating the \\textit{squared} measurements, in situations that deviate from such standard assumptions. We find that differences in detector sensitivities have a large impact on the comparative efficiency of the cross-correlation detection statistic, which is dominated by the alternative statistic when these differences reach one order of magnitude. This effect holds even when both the signal and noise distributions are Gaussian. While the presence of non-Gaussian signals has no mate...

  11. Factors Affecting Noise Levels of High-Speed Handpieces

    Science.gov (United States)

    2012-06-01

    office communication and increase patient anxiety. Purpose: To determine if three noise-reducing techniques utilized in larger scale , non- dental...hearing loss may cause confusion, fear, and loneliness , and that sometimes hearing loss is accompanied by dizziness, which would be a handicap in the...employee noise exposures equal or exceed an 8- hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or

  12. Educational Background and High School Maths Teachers ‘Specialism

    OpenAIRE

    Lin Wang(Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology (KIT), D-76128 Karlsruhe, Germany); Chang-huan. Feng

    2009-01-01

    Teachers’ Specialism is a world development trend and fashion, but also the needs and the direction of teacher education reform. After the latest curriculum reform, the educational reform and development of math,teachers have become universally concentrated and thoughtful in the field of mathematical education. The study adopting questionnaires and telephone interviews carried out a sample survey to 59 common high school math teachers from 3 provinces, and analyzed the connection between math...

  13. Refraction of high frequency noise in an arbitrary jet flow

    Science.gov (United States)

    Khavaran, Abbas; Krejsa, Eugene A.

    1994-01-01

    Refraction of high frequency noise by mean flow gradients in a jet is studied using the ray-tracing methods of geometrical acoustics. Both the two-dimensional (2D) and three-dimensional (3D) formulations are considered. In the former case, the mean flow is assumed parallel and the governing propagation equations are described by a system of four first order ordinary differential equations. The 3D formulation, on the other hand, accounts for the jet spreading as well as the axial flow development. In this case, a system of six first order differential equations are solved to trace a ray from its source location to an observer in the far field. For subsonic jets with a small spreading angle both methods lead to similar results outside the zone of silence. However, with increasing jet speed the two prediction models diverge to the point where the parallel flow assumption is no longer justified. The Doppler factor of supersonic jets as influenced by the refraction effects is discussed and compared with the conventional modified Doppler factor.

  14. A genetically encoded, high-signal-to-noise maltose sensor

    Energy Technology Data Exchange (ETDEWEB)

    Marvin, Jonathan S.; Schreiter, Eric R.; Echevarría, Ileabett M.; Looger, Loren L. (Puerto Rico); (HHMI)

    2012-10-23

    We describe the generation of a family of high-signal-to-noise single-wavelength genetically encoded indicators for maltose. This was achieved by insertion of circularly permuted fluorescent proteins into a bacterial periplasmic binding protein (PBP), Escherichia coli maltodextrin-binding protein, resulting in a four-color family of maltose indicators. The sensors were iteratively optimized to have sufficient brightness and maltose-dependent fluorescence increases for imaging, under both one- and two-photon illumination. We demonstrate that maltose affinity of the sensors can be tuned in a fashion largely independent of the fluorescent readout mechanism. Using literature mutations, the binding specificity could be altered to moderate sucrose preference, but with a significant loss of affinity. We use the soluble sensors in individual E. coli bacteria to observe rapid maltose transport across the plasma membrane, and membrane fusion versions of the sensors on mammalian cells to visualize the addition of maltose to extracellular media. The PBP superfamily includes scaffolds specific for a number of analytes whose visualization would be critical to the reverse engineering of complex systems such as neural networks, biosynthetic pathways, and signal transduction cascades. We expect the methodology outlined here to be useful in the development of indicators for many such analytes.

  15. Methodology for 1/f noise parameter extraction for high-voltage MOSFETs

    Science.gov (United States)

    Mavredakis, Nikolaos; Pflanzl, Walter; Seebacher, Ehrenfried; Bucher, Matthias

    2015-01-01

    This paper proposes a detailed low frequency noise (LFN) parameter extraction method for high-voltage (HV) MOSFETs at low (50 mV) and medium (3 V) drain biases. In Vd = 3 V region, noise coming from the channel is dominant while in linear region there is an extra contribution of noise from the drift region part especially for long-channel devices in strong inversion region. Flicker noise of 50 V and 20 V N- and P-channel HV-MOSFETs was measured over a large current range from weak to strong inversion, making possible the extraction of the noise parameters related to the different noise contributions, such as mobility fluctuations in low current regime, carrier number fluctuations and Coulomb scattering in medium and high current regime. In some cases, series resistance noise contribution especially at high current is apparent as well. The parameter extraction procedure is devised for a recently established charge-based flicker noise model for HV-MOSFETs. Noise parameters related to the carrier number fluctuation effect in the gate oxide extension in drift region are also extracted in high current regime of long-channel devices under low drain bias condition. The frequency exponent AF related to the slope of the measured noise spectra is also extracted. Measurements and analysis include both long as well as short N- and P-channel HV-MOSFETs.

  16. High temperature internal friction measurements of 3YTZP zirconia polycrystals. High temperature background and creep

    OpenAIRE

    Simas, P.; Castillo-Rodríguez, Miguel; Nó, M. L.; De-Bernardi, S.; Gómez-García, D.; Domínguez-Rodríguez, Alejandro; San Juan, J.

    2014-01-01

    This work focuses on the high-temperature mechanic properties of a 3 mol % yttria zirconia polycrystals (3YTZP), fabricated by hot-pressureless sintering. Systematic measurements of mechanical loss as a function of temperature and frequency were performed. An analytical method, based on the generalised Maxwell rheological model, has been used to analyse the high temperature internal friction background (HTB). This method has been previously applied to intermetallic compounds...

  17. High Speed Research Noise Prediction Code (HSRNOISE) User's and Theoretical Manual

    Science.gov (United States)

    Golub, Robert (Technical Monitor); Rawls, John W., Jr.; Yeager, Jessie C.

    2004-01-01

    This report describes a computer program, HSRNOISE, that predicts noise levels for a supersonic aircraft powered by mixed flow turbofan engines with rectangular mixer-ejector nozzles. It fully documents the noise prediction algorithms, provides instructions for executing the HSRNOISE code, and provides predicted noise levels for the High Speed Research (HSR) program Technology Concept (TC) aircraft. The component source noise prediction algorithms were developed jointly by Boeing, General Electric Aircraft Engines (GEAE), NASA and Pratt & Whitney during the course of the NASA HSR program. Modern Technologies Corporation developed an alternative mixer ejector jet noise prediction method under contract to GEAE that has also been incorporated into the HSRNOISE prediction code. Algorithms for determining propagation effects and calculating noise metrics were taken from the NASA Aircraft Noise Prediction Program.

  18. Noise in a coupling electromagnetic detecting system for high frequency gravitational waves

    Institute of Scientific and Technical Information of China (English)

    Li Jin; Li Fang-Yu; Zhong Yuan-Hong

    2009-01-01

    This paper discusses the basic categories of noise in detecting high frequency gravitational waves in the microwave band (~0.1-10 GHz), which contain shot noise from the laser and the thermal radiation photons, thermal noise from statistical fluctuation of the thermal photons and fluctuation of the temperature, radiation press noise on the fractal membrane, the noise caused by the scattering of the Gaussian Beam (GB) in the detecting tube and noise in the microwave radiometers. The analysis shows that a reasonable signal-to-noise ratio may be achieved for a detecting device with the fixed power of GB (105 W), only when the temperature of the environment is no more than T=l K, and the optimal length of the microwave radiometers is about 0.3 m.

  19. Design of noise barrier inspection system for high-speed railway

    Science.gov (United States)

    Liu, Bingqian; Shao, Shuangyun; Feng, Qibo; Ma, Le; Cholryong, Kim

    2016-10-01

    The damage of noise barriers will highly reduce the transportation safety of the high-speed railway. In this paper, an online inspection system of noise barrier based on laser vision for the safety of high-speed railway is proposed. The inspection system, mainly consisted of a fast camera and a line laser, installed in the first carriage of the high-speed CIT(Composited Inspection Train).A Laser line was projected on the surface of the noise barriers and the images of the light line were received by the camera while the train is running at high speed. The distance between the inspection system and the noise barrier can be obtained based on laser triangulation principle. The results of field tests show that the proposed system can meet the need of high speed and high accuracy to get the contour distortion of the noise barriers.

  20. Noise estimation Algorithms for Speech Enhancement in highly non-stationary Environments

    Directory of Open Access Journals (Sweden)

    Anuradha R Fukane

    2011-03-01

    Full Text Available A noise estimation algorithm plays an important role in speech enhancement. Speech enhancement for automatic speaker recognition system, Man-Machine communication, Voice recognition systems, speech coders, Hearing aids, Video conferencing and many applications are related to speech processing. All these systems are real world systems and input available for these systems is only the noisy speech signal, before applying to these systems we have to remove the noise component from noisy speech signal means enhanced speech signal can be applied to these systems. In most speech enhancement algorithms, it is assumed that an estimate of noise spectrum is available. Noise estimate is critical part and it is important for speech enhancement algorithms. If the noise estimate is too low then annoying residual noise will be available and if the noise estimate is too high then speech will get distorted and loss intelligibility. This paper focus on the different approaches of noise estimation. Section I introduction, Section II explains simple approach of Voice activity detector (VAD for noise estimation, Section III explains different classes of noise estimation algorithms, Section IV explains performance evaluation of noise estimation algorithms, Section V conclusion.

  1. The impact of compression of speech signal, background noise and acoustic disturbances on the effectiveness of speaker identification

    Science.gov (United States)

    Kamiński, K.; Dobrowolski, A. P.

    2017-04-01

    The paper presents the architecture and the results of optimization of selected elements of the Automatic Speaker Recognition (ASR) system that uses Gaussian Mixture Models (GMM) in the classification process. Optimization was performed on the process of selection of individual characteristics using the genetic algorithm and the parameters of Gaussian distributions used to describe individual voices. The system that was developed was tested in order to evaluate the impact of different compression methods used, among others, in landline, mobile, and VoIP telephony systems, on effectiveness of the speaker identification. Also, the results were presented of effectiveness of speaker identification at specific levels of noise with the speech signal and occurrence of other disturbances that could appear during phone calls, which made it possible to specify the spectrum of applications of the presented ASR system.

  2. Correlation of Electrical Noise with Non-radiative Current for High Power QWLs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The characteristics of low-frequency electrical noise, voltage-current (V-I) and electrical derivation for 980nm InGaAsP/InGaAs/GaAs high power double quantum well lasers(DQWLs) are measured under different conditions. The correlation of the low-frequency electrical noise with surface non-radiative current of devices is discussed. The results indicate the low-frequency electrical noise of 980nm DQWLs with high power is mainly 1/f noise and has good relation with the device surface current at low injection.

  3. Noise reduction of high-power supercontinuum sources by back seeding

    DEFF Research Database (Denmark)

    Moselund, Peter Morten; Frosz, Michael Henoch; Thomsen, Carsten L.

    2009-01-01

    We investigate noise reduction in seeded supercontinuum generation at powers above the supercontinuum generation threshold and show that seeding of supercontinuum is also beneficial at high pump powers.......We investigate noise reduction in seeded supercontinuum generation at powers above the supercontinuum generation threshold and show that seeding of supercontinuum is also beneficial at high pump powers....

  4. Design of a high performance low aerodynamic noise axial flow fan

    OpenAIRE

    2007-01-01

    The project starts with a description of the main sources of noise in an axial flow fan for concluding that the thing we should avoid is the trailing edge noise. After that the formulas for designing a fan and an aerodynamics background are presented. Once we get the results of these formulas a low noise optimization is carried on for leading us to a table of results where the main characteristics of design for our fan are obtained. After these tables the design of the fan is obtained with Pr...

  5. Low-noise moisture meter with high-speed LED techniques

    Science.gov (United States)

    Aikio, Rami; Lindström, Hannu; Suopajärvi, Pekka; Malinen, Jouko; Mäntylä, Markku

    2010-04-01

    Near infrared (NIR) spectroscopy can provide inexpensive, rapid and contact-free chemical content measurements for on-line, hand-held and laboratory applications. Traditionally multiwavelength NIR analyzers are based on incandescent lamp light sources with rotating filter wheels, even though designs relying on lamp technology and moving parts mean larger size, require frequent maintenance and eventually limit measurement speed of the system. Today, optical power and available wavelength range of LEDs enable their use in chemical content analyzers. In this publication, a paper moisture meter with high speed LED techniques is presented. A prototype developed at VTT utilizes an extended InGaAs detector to measure diffuse reflection at four NIR wavelengths ranging from 1.2 to 2.1 μm. Source LED currents are amplitude modulated with fixed sinusoidal frequencies. Optical signals at each wavelength are demodulated from the detector signal using real-time digital lock-in detection method on an FPGA. Moisture content is calculated and displayed on the embedded platform. The design allows very high speed operation, where the result is updated every 1 ms. Performance of the prototype system was studied by measuring a set of known sealed paper samples. Paper moisture measurement accuracy was 0.14, repeatability 0.01 and 2σ noise 0.04 moisture percent. Laboratory tests showed that channel crosstalk after detection is below background noise level. The measured signal-to-noise ratios per channel were 70 - 85 dB when all LEDs were on. The overall performance equals the level of incandescent lamp based on-line moisture meters currently in use in paper mill and process automation. The developed system forms a good basis also for other content measurements.

  6. Evaluation and Analysis of Noise Level at High-Traffic Locations in Gusau, Nigeria

    Directory of Open Access Journals (Sweden)

    Jacob O. Ebozoje

    2013-12-01

    Full Text Available The measurement of noise levels at high-traffic intersections of Gusau town is reported in this work. Five high-traffic locations tagged LOC-A, LOC-B, LOC-C, LOC-D and LOC-E were selected and evaluated at different periods of the day using an MS6700 IEC 651, ANSI.Si.4 Type-2 Sound Level meter. Result analyses indicates that LOC-C has the highest noise level with LNP = 95 and TNI = 94, while LOC-B has the lowest noise level with LNP = 82 and TNI = 67. These noise levels imply that Gusau metropolis has an unacceptable noise level, well above the globally recommended levels of 60-65 dB(A and the national recommended level of 82 dB(A. The paper therefore makes recommendations on minimizing these intolerable noise levels with consequences for environmental and human health in the study location.

  7. Real-time detection of small and dim moving objects in IR video sequences using a robust background estimator and a noise-adaptive double thresholding

    Science.gov (United States)

    Zingoni, Andrea; Diani, Marco; Corsini, Giovanni

    2016-10-01

    We developed an algorithm for automatically detecting small and poorly contrasted (dim) moving objects in real-time, within video sequences acquired through a steady infrared camera. The algorithm is suitable for different situations since it is independent of the background characteristics and of changes in illumination. Unlike other solutions, small objects of any size (up to single-pixel), either hotter or colder than the background, can be successfully detected. The algorithm is based on accurately estimating the background at the pixel level and then rejecting it. A novel approach permits background estimation to be robust to changes in the scene illumination and to noise, and not to be biased by the transit of moving objects. Care was taken in avoiding computationally costly procedures, in order to ensure the real-time performance even using low-cost hardware. The algorithm was tested on a dataset of 12 video sequences acquired in different conditions, providing promising results in terms of detection rate and false alarm rate, independently of background and objects characteristics. In addition, the detection map was produced frame by frame in real-time, using cheap commercial hardware. The algorithm is particularly suitable for applications in the fields of video-surveillance and computer vision. Its reliability and speed permit it to be used also in critical situations, like in search and rescue, defence and disaster monitoring.

  8. High Temperature Supersonic Jet Noise - Fundamental Studies and Control using Advanced Actuation Methods

    Science.gov (United States)

    2016-08-24

    decades, however methods of measurably controlling -reducing jet noise in an efficient and robust manner remain evasive. Previous research has shown...2016 1-May-2013 30-Apr-2016 High Temperature Supersonic Jet Noise - Fundamental Studies and Control using Advanced Actuation Methods The views...and Control using Advanced Actuation Methods Report Title Understanding and controlling jet noise has been the focus of analytical, computational and

  9. Model of small-scale self-focusing and spatial noise in high power laser driver

    Institute of Scientific and Technical Information of China (English)

    HU; Wei(胡巍); FU; Xiquan(傅喜泉); YU; Song; (喻松); GUO; Hong(郭弘)

    2002-01-01

    A linearization model was used to analyze the laser beam propagation in a high power laser driver and the influence of the small-scale self-focusing and spatial phase noise on beam quality in disk amplifiers. The quantitative relations between intensities of spatial phase noise, B-integral, and beam intensity contrast in near field are given explicitly. A spectrum specification of phase noise has been obtained by setting a limit to the contrast of an output beam.

  10. How to COAAD Images. II. A Coaddition Image that is Optimal for Any Purpose in the Background-dominated Noise Limit

    Science.gov (United States)

    Zackay, Barak; Ofek, Eran O.

    2017-02-01

    Image coaddition is one of the most basic operations that astronomers perform. In Paper I, we presented the optimal ways to coadd images in order to detect faint sources and to perform flux measurements under the assumption that the noise is approximately Gaussian. Here, we build on these results and derive from first principles a coaddition technique that is optimal for any hypothesis testing and measurement (e.g., source detection, flux or shape measurements, and star/galaxy separation), in the background-noise-dominated case. This method has several important properties. The pixels of the resulting coadded image are uncorrelated. This image preserves all the information (from the original individual images) on all spatial frequencies. Any hypothesis testing or measurement that can be done on all the individual images simultaneously, can be done on the coadded image without any loss of information. The PSF of this image is typically as narrow, or narrower than the PSF of the best image in the ensemble. Moreover, this image is practically indistinguishable from a regular single image, meaning that any code that measures any property on a regular astronomical image can be applied to it unchanged. In particular, the optimal source detection statistic derived in Paper I is reproduced by matched filtering this image with its own PSF. This coaddition process, which we call proper coaddition, can be understood as the maximum signal-to-noise ratio measurement of the Fourier transform of the image, weighted in such a way that the noise in the entire Fourier domain is of equal variance. This method has important implications for multi-epoch seeing-limited deep surveys, weak lensing galaxy shape measurements, and diffraction-limited imaging via speckle observations. The last topic will be covered in depth in future papers. We provide an implementation of this algorithm in MATLAB.

  11. High temperature sensor/microphone development for active noise control

    Science.gov (United States)

    Shrout, Thomas R.

    1993-01-01

    The industrial and scientific communities have shown genuine interest in electronic systems which can operate at high temperatures, among which are sensors to monitor noise, vibration, and acoustic emissions. Acoustic sensing can be accomplished by a wide variety of commercially available devices, including: simple piezoelectric sensors, accelerometers, strain gauges, proximity sensors, and fiber optics. Of the several sensing mechanisms investigated, piezoelectrics were found to be the most prevalent, because of their simplicity of design and application and, because of their high sensitivity over broad ranges of frequencies and temperature. Numerous piezoelectric materials are used in acoustic sensors today; but maximum use temperatures are imposed by their transition temperatures (T(sub c)) and by their resistivity. Lithium niobate, in single crystal form, has the highest operating temperature of any commercially available material, 650 C; but that is not high enough for future requirements. Only two piezoelectric materials show potential for use at 1000 C; AlN thin film reported to be piezoactive at 1150 C, and perovskite layer structure (PLS) materials, which possess among the highest T(sub c) (greater than 1500 C) reported for ferroelectrics. A ceramic PLS composition was chosen. The solid solution composition, 80% strontium niobate (SN) and 20% strontium tantalate (STa), with a T(sub c) approximately 1160 C, was hot forged, a process which concurrently sinters and renders the plate-like grains into a highly oriented configuration to enhance piezo properties. Poled samples of this composition showed coupling (k33) approximately 6 and piezoelectric strain constant (d33) approximately 3. Piezoactivity was seen at 1125 C, the highest temperature measurement reported for a ferroelectric ceramic. The high temperature piezoelectric responses of this, and similar PLS materials, opens the possibility of their use in electronic devices operating at temperatures up to

  12. High Order Wavelet-Based Multiresolution Technology for Airframe Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a novel, high-accuracy, high-fidelity, multiresolution (MRES), wavelet-based framework for efficient prediction of airframe noise sources and...

  13. A mathematical analysis of nuclear intensity dynamics for Mig1-GFP under consideration of bleaching effects and background noise in Saccharomyces cerevisiae.

    Science.gov (United States)

    Frey, Simone; Sott, Kristin; Smedh, Maria; Millat, Thomas; Dahl, Peter; Wolkenhauer, Olaf; Goksör, Mattias

    2011-01-01

    Fluorescence microscopy is an imaging technique that provides insights into signal transduction pathways through the generation of quantitative data, such as the spatiotemporal distribution of GFP-tagged proteins in signaling pathways. The data acquired are, however, usually a composition of both the GFP-tagged proteins of interest and of an autofluorescent background, which both undergo photobleaching during imaging. We here present a mathematical model based on ordinary differential equations that successfully describes the shuttling of intracellular Mig1-GFP under changing environmental conditions regarding glucose concentration. Our analysis separates the different bleaching rates of Mig1-GFP and background, and the background-to-Mig1-GFP ratio. By applying our model to experimental data, we can thus extract the Mig1-GFP signal from the overall acquired signal and investigate the influence of kinase and phosphatase on Mig1. We found a stronger regulation of Mig1 through its kinase than through its phosphatase when controlled by the glucose concentration, with a constant (de)phosphorylation rate independent of the glucose concentration. By replacing the term for decreasing excited Mig1-GFP concentration with a constant, we were able to reconstruct the dynamics of Mig1-GFP, as it would occur without bleaching and background noise. Our model effectively demonstrates how data, acquired with an optical microscope, can be processed and used for a systems biology analysis of signal transduction pathways.

  14. Noise levels in an urban Asian school environment

    OpenAIRE

    Chan, Karen M.K.; Chi Mei Li; Ma, Estella P.M.; Yiu, Edwin M.L.; Bradley McPherson

    2015-01-01

    Background noise is known to adversely affect speech perception and speech recognition. High levels of background noise in school classrooms may affect student learning, especially for those pupils who are learning in a second language. The current study aimed to determine the noise level and teacher speech-to-noise ratio (SNR) in Hong Kong classrooms. Noise level was measured in 146 occupied classrooms in 37 schools, including kindergartens, primary schools, secondary schools and special...

  15. Design and evaluation of modelocked semiconductor lasers for low noise and high stability

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Christiansen, Lotte Jin;

    2005-01-01

    We present work on design of monolithic mode-locked semiconductor lasers with focus on the gain medium. The use of highly inverted quantum wells in a low-loss waveguide enables both low quantum noise, low-chirped pulses and a large stability region. Broadband noise measurements are performed...

  16. High phase noise tolerant pilot-tone-aided DP-QPSK optical communication systems

    DEFF Research Database (Denmark)

    Zhang, Xu; Pang, Xiaodan; Deng, Lei

    2012-01-01

    In this paper we experimentally demonstrate a novel, high phase-noise tolerant, optical dual polarization (DP) quadrature phase-shift keying (QPSK) communication system based on pilot-tone-aided phase noise cancellation (PNC) algorithm. Vertical cavity surface emitting lasers (VCSELs...

  17. Theoretical analysis of quantum dot amplifiers with high saturation power and low noise figure

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2002-01-01

    Semiconductor quantum dot amplifiers are predicted to exhibit superior characteristics such as high gain, and output power and low noise. The analysis provides criteria and design guidelines for the realization of high quality amplifiers.......Semiconductor quantum dot amplifiers are predicted to exhibit superior characteristics such as high gain, and output power and low noise. The analysis provides criteria and design guidelines for the realization of high quality amplifiers....

  18. Ground-roll noise extraction and suppression using high-resolution linear Radon transform

    Science.gov (United States)

    Hu, Yue; Wang, Limin; Cheng, Feng; Luo, Yinhe; Shen, Chao; Mi, Binbin

    2016-05-01

    Ground-roll is a main type of strong noises in petroleum seismic exploration. Suppression of this kind of noise is essential to improve the signal-to-noise ratio of seismic data. In the time-offset (t-x) domain, the ground-roll noise and the effective waves (e.g., direct waves, reflections) overlap with each other in terms of time and frequency, which make it difficult to suppress ground roll noise in exploration seismic data. However, significant different features shown in the frequency-velocity (f-v) domain make it possible to separate ground roll noise and effective waves effectively. We propose a novel method to separate them using high-resolution linear Radon transform (LRT). Amplitude and phase information is preserved during the proposed quasi-reversible transformation. The reversibility and linearity of LRT provide a foundation for ground-roll noise suppression in the f-v domain. We extract the energy of ground-roll noise in the f-v domain, and transform the extracted part back to the t-x domain to obtain the ground-roll noise shot gather. Finally, the extracted ground-roll noise is subtracted from the original data arithmetically. Theoretical tests and a real world example have been implemented to illustrate that the ground-roll noise suppression can be achieved with negligible distortion of the effective signals. When compared with the adaptive ground-roll attenuation method and the K-L transform method, the real world example shows the superiority of our method in suppressing the ground-roll noise and preserving the amplitude and phase information of effective waves.

  19. Study of the neutron background noise generated by muons in the Edelweiss-2 experiment; Etude du bruit de fond neutron induit par les muons dans l'experience EDELWEISS-2

    Energy Technology Data Exchange (ETDEWEB)

    Chabert, L

    2004-07-01

    This thesis contributes to the Edelweiss experiment whose aim is to detect interactions between neutralinos and target nuclei. Bolometers used in Edelweiss combine the detection of phonons with the detection of electric charges generated by the energy deposition. This double detection enables us to discard background signals due to electronic interactions and soon detection sensitivity of the experiment will be limited by the neutron background noise due to residual cosmic muons. This work is dedicated to a detailed study of muon inelastic interactions and the consequent production of neutrons. Simulations show that the expected neutron flux is so high that the direct detection of muons is required in order to link it to the neutron signal issued by the bolometer. Results from simulations show that plastic scintillators might be the main components of the muon detector.

  20. Flicker noise in high-speed p-i-n photodiodes

    CERN Document Server

    Rubiola, E; Yu, N; Maleki, L; Rubiola, Enrico; Salik, Ertan; Yu, Nan; Maleki, Lute

    2005-01-01

    The microwave signal at the output of a photodiode that detects a modulated optical beam contains the phase noise phi(t) and the amplitude noise alpha(t) of the detector. Beside the white noise, which is well understood, the spectral densities S_phi(f) and S_alpha(f) show flicker noise, proportional to 1/f. We report on the measurement of the phase and amplitude noise of high-speed p-i-n photodiodes. The main result is that the flicker coefficient of the samples is approximately 1E-12 rad^2/Hz (-120dB) for phase noise, and approximately 1E-12 Hz^-1 (-120dB) for amplitude noise. These values could be observed only after solving a number of experimental problems and in a protected environment. By contrast, in ordinary conditions insufficient EMI isolation, and also insufficient mechanical isolation, are responsible for additional noise to be taken in. This suggests that if package and EMC are revisited, applications can take the full benefit from the surprisingly low noise of the p-i-n photodiodes.

  1. Common mode noise modeling and its suppression in ultra-high efficiency full bridge boost converter

    DEFF Research Database (Denmark)

    Makda, Ishtiyaq Ahmed; Nymand, Morten; Madawala, Udaya

    2013-01-01

    In this paper, common mode noise modeling of low-voltage high-current isolated full bridge boost dc-dc converters intended for fuel cell application is presented. Due to the tightly coupled primary and secondary windings of the transformer, such converter has inherently large capacitive coupling...... between input and output which is normally associated with high common mode noise generation. In this work, common mode noise sources in the converter are identified, and a common mode noise model is developed. Based on the established noise model, a practical CM filter is designed to comply...... with the CISPR-A requirements. Finally, a 3kW dc-dc converter including filters has been built and tested to verify the theoretical model. Experimental results confirm the theoretical analysis of the converter....

  2. "Gaining Power through Education": Experiences of Honduran Students from High Poverty Backgrounds

    Science.gov (United States)

    Mather, Peter C.; Zempter, Christy; Ngumbi, Elizabeth; Nakama, Yuki; Manley, David; Cox, Haley

    2017-01-01

    This is a study of students from high-poverty backgrounds attending universities in Honduras. Based on a series of individual and focus group interviews, the researchers found students from high-poverty backgrounds face numerous practical challenges in persisting in higher education. Despite these challenges, participants succeeded due to a…

  3. High-speed helicopter rotor noise - Shock waves as a potent source of sound

    Science.gov (United States)

    Farassat, F.; Lee, Yung-Jang; Tadghighi, H.; Holz, R.

    1991-01-01

    In this paper we discuss the problem of high speed rotor noise prediction. In particular, we propose that from the point of view of the acoustic analogy, shocks around rotating blades are sources of sound. We show that, although for a wing at uniform steady rectilinear motion with shocks the volume quadrupole and shock sources cancel in the far field to the order of 1/r, this cannot happen for rotating blades. In this case, some cancellation between volume quadrupoles and shock sources occurs, yet the remaining shock noise contribution is still potent. A formula for shock noise prediction is presented based on mapping the deformable shock surface to a time independent region. The resulting equation is similar to Formulation 1A of Langley. Shock noise prediction for a hovering model rotor for which experimental noise data exist is presented. The comparison of measured and predicted acoustic data shows good agreement.

  4. Comparative Studies on Low Noise Greases Operating under High Temperature Oxidation Conditions

    Institute of Scientific and Technical Information of China (English)

    Xiong Chunhua; Mi Hongying; Feng Qiang; Wu Baojie

    2014-01-01

    Oxidation induction time (OIT) testing by differential scanning calorimetry (DSC) was used to evaluate the oxidation resistance of lubricating greases. Under the high temperature condition, bearing noise was detected when grease passed the initial stable stage of oxidation. The chemical and physical structure of grease samples before and after high tem-perature oxidation were also analyzed by FT-IR spectrometry and scanning electron microscopy (SEM), then the effects of oxidation at high temperature on bearing noise were investigated. It is found out that for lithium greases, oxidation of base oil and thickener is the main reason responsible for the increasing bearing noise. As regards the polyurea greases, the change of ifber microstructure at high temperature is the main reason for the increasing bearing noise.

  5. Very High Gain and Low Noise Near Infrared Single Photon Counting Detectors and Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Amplification Technologies Inc ("ATI") proposes to develop the enabling material and device technology for the design of ultra low noise, high gain and low...

  6. Ultra-low Noise, High Bandwidth, 1550nm HgCdTe APD Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Voxtel Inc. proposes to optimize the design of a large area, 1.55?m sensitive HgCdTe avalanche photodiode (APD) that achieves high gain with nearly no excess noise....

  7. High Order Wavelet-Based Multiresolution Technology for Airframe Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An integrated framework is proposed for efficient prediction of rotorcraft and airframe noise. A novel wavelet-based multiresolution technique and high-order...

  8. High Pressure Air Jet in the Endoscopic Preparation Room: Risk of Noise Exposure on Occupational Health

    OpenAIRE

    King-Wah Chiu; Lung-Sheng Lu; Cheng-Kun Wu

    2015-01-01

    After high-level disinfection of gastrointestinal endoscopes, they are hung to dry in order to prevent residual water droplets impact on patient health. To allow for quick drying and clinical reuse, some endoscopic units use a high pressure air jet (HPAJ) to remove the water droplets on the endoscopes. The purpose of this study was to evaluate the excessive noise exposure with the use of HPAJ in endoscopic preparation room and to investigate the risk to occupational health. Noise assessment w...

  9. 1/f noise in forward biased high voltage 4H-SiC Schottky diodes

    Science.gov (United States)

    Shabunina, Eugenia I.; Levinshtein, Michael E.; Shmidt, Natalia M.; Ivanov, Pavel A.; Palmour, John W.

    2014-06-01

    The 1/f noise has been investigated for the first time at 300 and 77 K in high-quality 4H-SiC Schottky diodes. It is shown that, at 77 K, the dependence of the spectral noise density on current, SI(I), differs fundamentally between the cases of the current flowing through the main part of the diode with a comparatively high barrier and the current flowing through the nano-sized patches with a comparatively low barrier.

  10. Background and Scattered-Light Subtraction in the High-Resolution Echelle Modes of the Space Telescope Imaging Spectrograph

    Science.gov (United States)

    Howk, J. Christopher; Sembach, Kenneth R.

    2000-05-01

    We present a simple, effective approach for estimating the on-order backgrounds of spectra taken with the highest resolution modes of the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. Our scheme for determining the on-order background spectrum for STIS E140H and E230H observations uses moderate-order polynomial fits to the interorder scattered light visible in the two-dimensional STIS MAMA images. We present a suite of high-resolution STIS spectra to demonstrate that our background-subtraction routine produces the correct overall zero point as judged by the small residual flux levels in the centers of strongly saturated interstellar absorption lines. Although there are multiple sources of background light in STIS echelle mode data, this simple approach works very well for wavelengths longward of Lyα (λ>~1215 Å). At shorter wavelengths, the smaller order separation and generally lower signal-to-noise ratios of the data can reduce the effectiveness of our background estimation procedure. Slight artifacts in the background-subtracted spectrum can be seen in some cases, particularly at wavelengths of B2B and the GHRS first-order G160M observations of the early-type star HD 218915. We find no significant differences between the GHRS data and the STIS data reduced with our method in either case. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

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

    Science.gov (United States)

    Hakso, A. W.; Seats, K.

    2015-12-01

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

  12. High Resolution Viscosity Measurement by Thermal Noise Detection

    Directory of Open Access Journals (Sweden)

    Felipe Aguilar Sandoval

    2015-11-01

    Full Text Available An interferometric method is implemented in order to accurately assess the thermal fluctuations of a micro-cantilever sensor in liquid environments. The power spectrum density (PSD of thermal fluctuations together with Sader’s model of the cantilever allow for the indirect measurement of the liquid viscosity with good accuracy. The good quality of the deflection signal and the characteristic low noise of the instrument allow for the detection and corrections of drawbacks due to both the cantilever shape irregularities and the uncertainties on the position of the laser spot at the fluctuating end of the cantilever. Variation of viscosity below 0.03 mPa·s was detected with the alternative to achieve measurements with a volume as low as 50 µL.

  13. Development of low read noise high conversion gain CMOS image sensor for photon counting level imaging

    Science.gov (United States)

    Seo, Min-Woong; Kawahito, Shoji; Kagawa, Keiichiro; Yasutomi, Keita

    2016-05-01

    A CMOS image sensor with deep sub-electron read noise and high pixel conversion gain has been developed. Its performance is recognized through image outputs from an area image sensor, confirming the capability of photoelectroncounting- level imaging. To achieve high conversion gain, the proposed pixel has special structures to reduce the parasitic capacitances around FD node. As a result, the pixel conversion gain is increased due to the optimized FD node capacitance, and the noise performance is also improved by removing two noise sources from power supply. For the first time, high contrast images from the reset-gate-less CMOS image sensor, with less than 0.3e- rms noise level, have been generated at an extremely low light level of a few electrons per pixel. In addition, the photon-counting capability of the developed CMOS imager is demonstrated by a measurement, photoelectron-counting histogram (PCH).

  14. Electro-optic comb based real time ultra-high sensitivity phase noise measurement system for high frequency microwaves.

    Science.gov (United States)

    Kuse, N; Fermann, M E

    2017-06-06

    Recent progress in ultra low phase noise microwave generation indispensably depends on ultra low phase noise characterization systems. However, achieving high sensitivity currently relies on time consuming averaging via cross correlation, which sometimes even underestimates phase noise because of residual correlations. Moreover, extending high sensitivity phase noise measurements to microwaves beyond 10 GHz is very difficult because of the lack of suitable high frequency microwave components. In this work, we introduce a delayed self-heterodyne method in conjunction with sensitivity enhancement via the use of higher order comb modes from an electro-optic comb for ultra-high sensitivity phase noise measurements. The method obviates the need for any high frequency RF components and has a frequency measurement range limited only by the bandwidth (100 GHz) of current electro-optic modulators. The estimated noise floor is as low as -133 dBc/Hz, -155 dBc/Hz, -170 dBc/Hz and -171 dBc/Hz without cross correlation at 1 kHz, 10 kHz, 100 kHz and 1 MHz Fourier offset frequency for a 10 GHz carrier, respectively. Moreover, since no cross correlation is necessary, RF oscillator phase noise can be directly suppressed via feedback up to 100 kHz frequency offset.

  15. High-impedance NbSi TES sensors for studying the cosmic microwave background radiation

    Science.gov (United States)

    Nones, C.; Marnieros, S.; Benoit, A.; Bergé, L.; Bideaud, A.; Camus, P.; Dumoulin, L.; Monfardini, A.; Rigaut, O.

    2012-12-01

    Precise measurements of the cosmic microwave background (CMB) are crucial in cosmology because any proposed model of the universe must account for the features of this radiation. The CMB has a thermal blackbody spectrum at a temperature of 2.725 K, i.e. the spectrum peaks in the microwave range frequency of 160.2 GHz, corresponding to a 1.9-mm wavelength. Of all CMB measurements that the scientific community has not yet been able to perform, the CMB B-mode polarization is probably the most challenging from the instrumental point of view. The signature of primordial gravitational waves, which give rise to a B-type polarization, is one of the goals in cosmology today and amongst the first objectives in the field. For this purpose, high-performance low-temperature bolometric cameras, made of thousands of pixels, are currently being developed by many groups, which will improve the sensitivity to B-mode CMB polarization by one or two orders of magnitude compared to the Planck satellite HFI detectors. We present here a new bolometer structure that is able to increase the pixel sensitivities and to simplify the fabrication procedure. This innovative device replaces delicate membrane-based structures and eliminates the mediation of phonons: the incoming energy is directly captured and measured in the electron bath of an appropriate sensor and the thermal decoupling is achieved via the intrinsic electron-phonon decoupling of the sensor at very low temperature. Reported results come from a 204-pixel array of NbxSi1-x transition edge sensors with a meander structure fabricated on a 2-inch silicon wafer using electron-beam co-evaporation and a cleanroom lithography process. To validate the application of this device to CMB measurements, we have performed an optical calibration of our sample in the focal plane of a dilution cryostat test bench. We have demonstrated a light absorption close to 20% and an optical noise equivalent power of about 7×10-16 W/√Hz, which is highly

  16. MEMS microphone innovations towards high signal to noise ratios (Conference Presentation) (Plenary Presentation)

    Science.gov (United States)

    Dehé, Alfons

    2017-06-01

    After decades of research and more than ten years of successful production in very high volumes Silicon MEMS microphones are mature and unbeatable in form factor and robustness. Audio applications such as video, noise cancellation and speech recognition are key differentiators in smart phones. Microphones with low self-noise enable those functions. Backplate-free microphones enter the signal to noise ratios above 70dB(A). This talk will describe state of the art MEMS technology of Infineon Technologies. An outlook on future technologies such as the comb sensor microphone will be given.

  17. Jet noise of high aspect-ratio rectangular nozzles with application to pneumatic high-lift devices

    Science.gov (United States)

    Munro, Scott Edward

    Circulation control wings are a type of pneumatic high-lift device that have been extensively researched as to their aerodynamic benefits. However, there has been little research into the possible airframe noise reduction benefits. The key element of noise is the jet noise associated with the jet sheet emitted from the blowing slot. This jet sheet is essentially a high aspect-ratio rectangular jet. This study directly compared far-field noise emissions from a state-of-the-art circulation control wing high lift configuration, and a conventional wing also configured for high lift. Results indicated that a circulation control wing had a significant acoustic advantage over a conventional wing for identical lift performance. A high aspect-ratio nozzle was fabricated to study the general characteristics of high aspect-ratio jets with aspect ratios from 100 to 3000. The results of this study provided the basic elements in understanding how to reduce the noise from a circulation control wing. High aspect-ratio nozzle results showed that the jet noise of this type of jet was proportional to the 8th power of the jet velocity. It was also found that the jet noise was proportional to the slot height to the 3/2 power and slot width to the 1/2 power. Fluid dynamic experiments were also performed on the high aspect-ratio nozzle. Single hot-wire experiments indicated that the jet exhaust from the high aspect-ratio nozzle was similar to a 2-d turbulent jet. Two-wire space-correlation experiments were performed to attempt to find a relationship between the slot height of the jet and the length-scale of the flow noise generating turbulence structure. The turbulent eddy convection velocity was also calculated, and was found to vary with the local centerline velocity, and also as a function of the frequency of the eddy.

  18. High-order noise analysis for low dose iterative image reconstruction methods: ASIR, IRIS, and MBAI

    Science.gov (United States)

    Do, Synho; Singh, Sarabjeet; Kalra, Mannudeep K.; Karl, W. Clem; Brady, Thomas J.; Pien, Homer

    2011-03-01

    Iterative reconstruction techniques (IRTs) has been shown to suppress noise significantly in low dose CT imaging. However, medical doctors hesitate to accept this new technology because visual impression of IRT images are different from full-dose filtered back-projection (FBP) images. Most common noise measurements such as the mean and standard deviation of homogeneous region in the image that do not provide sufficient characterization of noise statistics when probability density function becomes non-Gaussian. In this study, we measure L-moments of intensity values of images acquired at 10% of normal dose and reconstructed by IRT methods of two state-of-art clinical scanners (i.e., GE HDCT and Siemens DSCT flash) by keeping dosage level identical to each other. The high- and low-dose scans (i.e., 10% of high dose) were acquired from each scanner and L-moments of noise patches were calculated for the comparison.

  19. Design and validation of the high performance and low noise CQU-DTU-LN1 airfoils

    DEFF Research Database (Denmark)

    Cheng, Jiangtao; Zhu, Wei Jun; Fischer, Andreas

    2014-01-01

    with the blade element momentum theory, the viscous-inviscid XFOIL code and an airfoil self-noise prediction model, an optimization algorithm has been developed for designing the high performance and low noise CQU-DTU-LN1 series of airfoils with targets of maximum power coefficient and low noise emission......This paper presents the design and validation of the high performance and low noise Chong Qing University and Technical University of Denmark LN1 (CQU-DTU-LN1) series of airfoils for wind turbine applications. The new design method uses target characteristics of wind turbine airfoils in the design...... emission between the CQU-DTU-LN118 airfoil and the National Advisory Committee for Aeronautics (NACA) 64618 airfoil, which is used in modern wind turbine blades, are carried out. Copyright © 2013 John Wiley & Sons, Ltd....

  20. Sources of high frequency seismic noise: insights from a dense network of ~250 stations in northern Alsace (France)

    Science.gov (United States)

    Vergne, Jerome; Blachet, Antoine; Lehujeur, Maximilien

    2015-04-01

    Monitoring local or regional seismic activity requires stations having a low level of background seismic noise at frequencies higher than few tenths of Hertz. Network operators are well aware that the seismic quality of a site depends on several aspects, among them its geological setting and the proximity of roads, railways, industries or trees. Often, the impact of each noise source is only qualitatively known which precludes estimating the quality of potential future sites before they are tested or installed. Here, we want to take advantage of a very dense temporary network deployed in Northern Alsace (France) to assess the effect of various kinds of potential sources on the level of seismic noise observed in the frequency range 0.2-50 Hz. In September 2014, more than 250 seismic stations (FairfieldNodal@ Zland nodes with 10Hz vertical geophone) have been installed every 1.5 km over a ~25km diameter disc centred on the deep geothermal sites of Soultz-sous-Forêts and Rittershoffen. This region exhibits variable degrees of human imprints from quite remote areas to sectors with high traffic roads and big villages. It also encompasses both the deep sedimentary basin of the Rhine graben and the piedmont of the Vosges massif with exposed bedrock. For each site we processed the continuous data to estimate probability density functions of the power spectral densities. At frequencies higher than 1 Hz most sites show a clear temporal modulation of seismic noise related to human activity with the well-known variations between day and night and between weekdays and weekends. Moreover we observe a clear evolution of the spatial distribution of seismic noise levels with frequency. Basically, between 0.5 and 4 Hz the geological setting modulates the level of seismic noise. At higher frequencies, the amplitude of seismic noise appears mostly related to the distance to nearby roads. Based on road maps and traffic estimation, a forward approach is performed to model the induced

  1. Coherent Dual Comb Spectroscopy at High Signal to Noise

    CERN Document Server

    Coddington, I; Newbury, N R

    2010-01-01

    Two frequency combs can be used to measure the full complex response of a sample in a configuration which can be alternatively viewed as the equivalent of a dispersive Fourier transform spectrometer, infrared time domain spectrometer, or a multiheterodyne laser spectrometer. This dual comb spectrometer retains the frequency accuracy and resolution inherent to the comb sources. We discuss, in detail, the specific design of our coherent dual-comb spectrometer and demonstrate the potential of this technique by measuring the first overtone vibration of hydrogen cyanide, centered at 194 THz (1545 nm). We measure the fully normalized, complex response of the gas over a 9 THz bandwidth at 220 MHz frequency resolution yielding 41,000 resolution elements. The average spectral signal-to-noise ratio (SNR) is 2,500 for both the fractional absorption and the phase, with a peak SNR of 4,000 corresponding to a fractional absorption sensitivity of 0.025% and phase sensitivity of 250 microradians. As the spectral coverage of ...

  2. High-frequency audiometry: A means for early diagnosis of noise-induced hearing loss

    OpenAIRE

    Amir H Mehrparvar; Seyyed J Mirmohammadi; Abbas Ghoreyshi; Abolfazl Mollasadeghi; Ziba Loukzadeh

    2011-01-01

    Noise-induced hearing loss (NIHL), an irreversible disorder, is a common problem in industrial settings. Early diagnosis of NIHL can help prevent the progression of hearing loss, especially in speech frequencies. For early diagnosis of NIHL, audiometry is performed routinely in conventional frequencies. We designed this study to compare the effect of noise on high-frequency audiometry (HFA) and conventional audiometry. In a historical cohort study, we compared hearing threshold and prevalence...

  3. Component-based model to predict aerodynamic noise from high-speed train pantographs

    Science.gov (United States)

    Latorre Iglesias, E.; Thompson, D. J.; Smith, M. G.

    2017-04-01

    At typical speeds of modern high-speed trains the aerodynamic noise produced by the airflow over the pantograph is a significant source of noise. Although numerical models can be used to predict this they are still very computationally intensive. A semi-empirical component-based prediction model is proposed to predict the aerodynamic noise from train pantographs. The pantograph is approximated as an assembly of cylinders and bars with particular cross-sections. An empirical database is used to obtain the coefficients of the model to account for various factors: incident flow speed, diameter, cross-sectional shape, yaw angle, rounded edges, length-to-width ratio, incoming turbulence and directivity. The overall noise from the pantograph is obtained as the incoherent sum of the predicted noise from the different pantograph struts. The model is validated using available wind tunnel noise measurements of two full-size pantographs. The results show the potential of the semi-empirical model to be used as a rapid tool to predict aerodynamic noise from train pantographs.

  4. On the bremsstrahlung background correction to the high-energy Compton spectroscopy

    Indian Academy of Sciences (India)

    S Mathur; B L Ahuja

    2005-07-01

    A methodology for bremsstrahlung (BS) background correction to extract a true Compton profile in high-energy Compton scattering experiments is presented. The BS background profiles for Hg, computed within the Born approximation, are estimated for different values of incident energy. It is seen for the first time that the BS background contribution in high-energy Compton profile experiments like those employing third generation synchrotron radiation sources comes out to be significant and non-linear. Further, it is found that the incorporation of BS correction in data reduction of such an experiment performed on Hg at 662 keV energy helps in reconciliation of theory and experiment.

  5. Minimum Climb to Cruise Noise Trajectories Modeled for the High Speed Civil Transport

    Science.gov (United States)

    Berton, Jeffrey J.

    1998-01-01

    The proposed U.S. High Speed Civil Transport (HSCT) will revolutionize commercial air travel by providing economical supersonic passenger service to destinations worldwide. Unlike the high-bypass turbofan engines that propel today's subsonic airliners, HSCT engines will have much higher jet exhaust speeds. Jet noise, caused by the turbulent mixing of high-speed exhaust with the surrounding air, poses a significant challenge for HSCT engine designers. To resolve this challenge, engineers have designed advanced mixer rejector nozzles that reduce HSCT jet noise to airport noise certification levels by entraining and mixing large quantities of ambient air with the engines' jet streams. Although this works well during the first several minutes of flight, far away from the airport, as the HSCT gains speed and climbs, poor ejector inlet recovery and ejector ram drag contribute to poor thrust, making it advantageous to turn off the ejector. Doing so prematurely, however, can cause unacceptable noise levels to propagate to the ground, even when the aircraft is many miles from the airport. This situation lends itself ideally to optimization, where the aircraft trajectory, throttle setting, and ejector setting can be varied (subject to practical aircraft constraints) to minimize the noise propagated to the ground. A method was developed at the NASA Lewis Research Center that employs a variation of the classic energy state approximation: a trajectory analysis technique historically used to minimize climb time or fuel burned in many aircraft problems. To minimize the noise on the ground at any given throttle setting, high aircraft altitudes are desirable; but the HSCT may either climb quickly to high altitudes using a high, noisy throttle setting or climb more slowly at a lower, quieter throttle setting. An optimizer has been programmed into NASA's existing aircraft and noise analysis codes to balance these options by dynamically choosing the best altitude-velocity path and

  6. A novel SWIR detector with an ultra-high internal gain and negligible excess noise

    Science.gov (United States)

    Mohseni, H.; Memis, O. G.; Kong, S. C.; Katsnelson, A.; Wu, W.

    2007-10-01

    Short wave infrared (SWIR) imaging systems have several advantages due to the spectral content of the nightglow and better discrimination against camouflage. Achieving single photon detection sensitivity can significantly improve the image quality of these systems. However, the internal noise of the detector and readout circuits are significant barriers to achieve this goal. One can prove that the noise limitations of the readout can be alleviated, if the detector exhibits sufficiently high internal gain. Unfortunately, the existing detectors with internal gain have a very high noise as well. Here we present the recent results from our novel FOcalized Carrier aUgmented Sensor (FOCUS). It utilizes very high charge compression into a nano-injector, and subsequent carrier injection to achieve high quantum efficiency and high sensitivity at short infrared at room temperature. We obtain internal gain values exceeding several thousand at bias values of less than 1 volt. The current responsivity at 1.55 μm is more than 1500 A/W, and the noise equivalent power (NEP) is less that 0.5 x10 -15 W/Hz 1/2 at room temperature. These are significantly better than the performance of the existing room temperature devices with internal gain. Also, unlike avalanche-based photodiodes, the measured excess noise factor for our device is near unity, even at very high gain values. The stable gain of the device combined with the low operating voltage are unique advantages of this technology for high-performance SWIR imaging arrays.

  7. Surrogate Based Optimization of Aerodynamic Noise for Streamlined Shape of High Speed Trains

    Directory of Open Access Journals (Sweden)

    Zhenxu Sun

    2017-02-01

    Full Text Available Aerodynamic noise increases with the sixth power of the running speed. As the speed increases, aerodynamic noise becomes predominant and begins to be the main noise source at a certain high speed. As a result, aerodynamic noise has to be focused on when designing new high-speed trains. In order to perform the aerodynamic noise optimization, the equivalent continuous sound pressure level (SPL has been used in the present paper, which could take all of the far field observation probes into consideration. The Non-Linear Acoustics Solver (NLAS approach has been utilized for acoustic calculation. With the use of Kriging surrogate model, a multi-objective optimization of the streamlined shape of high-speed trains has been performed, which takes the noise level in the far field and the drag of the whole train as the objectives. To efficiently construct the Kriging model, the cross validation approach has been adopted. Optimization results reveal that both the equivalent continuous sound pressure level and the drag of the whole train are reduced in a certain extent.

  8. Calculation Model for the Propagation of Audible Noise from High Voltage Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    LI Xuebao; CUI Xiang; LU Tiebing; HE Jiamei

    2013-01-01

    Audible noise from high voltage transmission lines' corona discharge has become one of the decisive factors affecting design of high voltage transmission lines,thus it is very important to study the spatial propagation characteristics of audible noise for its accurate prediction.A calculation model for the propagation of audible noise is presented in this paper,which is based on the basic equation of the sound wave and can involve the influences of the atmosphere absorption and ground effects.The effects of different ground impedances and the atmospheric attenuation on the distribution of sound pressure level are discussed in this paper.The results show that the atmospheric absorption may increase the attenuation of the audible noise,and the ground surface affects both the amplitude and phase of the sound.The spatial distribution fluctuates considering the ground effects.The atmospheric attenuation and the ground effect are closely related to the frequency of the noise.In the frequency range of the audible noise,the influence of atmospheric attenuation on the spatial propagation characteristics is more obvious in high frequency while ground has significant influences in low frequency.

  9. High Bypass Ratio Jet Noise Reduction and Installation Effects Including Shielding Effectiveness

    Science.gov (United States)

    Thomas, Russell H.; Czech, Michael J.; Doty, Michael J.

    2013-01-01

    An experimental investigation was performed to study the propulsion airframe aeroacoustic installation effects of a separate flow jet nozzle with a Hybrid Wing Body aircraft configuration where the engine is installed above the wing. Prior understanding of the jet noise shielding effectiveness was extended to a bypass ratio ten application as a function of nozzle configuration, chevron type, axial spacing, and installation effects from additional airframe components. Chevron types included fan chevrons that are uniform circumferentially around the fan nozzle and T-fan type chevrons that are asymmetrical circumferentially. In isolated testing without a pylon, uniform chevrons compared to T-fan chevrons showed slightly more low frequency reduction offset by more high frequency increase. Phased array localization shows that at this bypass ratio chevrons still move peak jet noise source locations upstream but not to nearly the extent, as a function of frequency, as for lower bypass ratio jets. For baseline nozzles without chevrons, the basic pylon effect has been greatly reduced compared to that seen for lower bypass ratio jets. Compared to Tfan chevrons without a pylon, the combination with a standard pylon results in more high frequency noise increase and an overall higher noise level. Shielded by an airframe surface 2.17 fan diameters from nozzle to airframe trailing edge, the T-fan chevron nozzle can produce reductions in jet noise of as much as 8 dB at high frequencies and upstream angles. Noise reduction from shielding decreases with decreasing frequency and with increasing angle from the jet inlet. Beyond an angle of 130 degrees there is almost no noise reduction from shielding. Increasing chevron immersion more than what is already an aggressive design is not advantageous for noise reduction. The addition of airframe control surfaces, including vertical stabilizers and elevon deflection, showed only a small overall impact. Based on the test results, the best

  10. The current-voltage and noise properties of high temperature superconductor SNS and grain boundary junctions

    CERN Document Server

    McGordon, A

    1999-01-01

    transport that was dominated by the interlayer material, but supercurrent transport that could be due to pinhole shorts. In addition, both geometries, especially the sandwich junction, showed large amounts of normal state noise making these junctions unsuitable for device applications. The effect of shining laser light onto a junction was investigated. The effects on the I-V characteristic were unobservable with the experimental resolution available. The effect of the light on the critical current noise of the junction was to reduce the noise peak slightly when compared to the unilluminated case- the reduction was of the order of 10%, comparable with experimental resolution. The study of the noise from Josephson Junctions is an intense field of research. Despite this, no clear picture of the current transport in these devices has emerged. Without the detailed understanding of the mechanisms of current transport in High Temperature Superconductor junctions, the design of superconducting electronics will not mo...

  11. Optimum Climb to Cruise Noise Trajectories for the High Speed Civil Transport

    Science.gov (United States)

    Berton, Jeffrey J.

    2003-01-01

    By entraining large quantities of ambient air into advanced ejector nozzles, the jet noise of the proposed High Speed Civil Transport (HSCT) is expected to be reduced to levels acceptable for airport-vicinity noise certification. Away from the airport, however, this entrained air is shut off and the engines are powered up from their cutback levels to provide better thrust for the climb to cruise altitude. Unsuppressed jet noise levels propagating to the ground far from the airport are expected to be high. Complicating this problem is the HSCT's relative noise level with respect to the subsonic commercial fleet of 2010, which is expected to be much quieter than it is today after the retirement of older, louder, domestic stage II aircraft by the year 2000. In this study, the classic energy state approximation theory is extended to calculate trajectories that minimize the climb to cruise noise of the HSCT. The optimizer dynamically chooses the optimal altitude velocity trajectory, the engine power setting, and whether the ejector should be stowed or deployed with respect to practical aircraft climb constraints and noise limits.

  12. High Density Impulse Noise Detection using Fuzzy C-means Algorithm

    Directory of Open Access Journals (Sweden)

    Isha Singh

    2016-01-01

    Full Text Available A new technique for detecting the high density impulse noise from corrupted images using Fuzzy C-means algorithm is proposed. The algorithm is iterative in nature and preserves more image details in high noise environment. Fuzzy C-means is initially used to cluster the image data. The application of Fuzzy C-means algorithm in the detection phase provides an optimum classification of noisy data and uncorrupted image data so that the pictorial information remains well preserved. Experimental results show that the proposed algorithm significantly outperforms existing well-known techniques. Results show that with the increase in percentage of noise density, the performance of the algorithm is not degraded. Furthermore, the varying window size in the two detection stages provides more efficient results in terms of low false alarm rate and miss detection rate. The simple structure of the algorithm to detect impulse noise makes it useful for various applications like satellite imaging, remote sensing, medical imaging diagnosis and military survillance. After the efficient detection of noise, the existing filtering techniques can be used for the removal of noise.Defence Science Journal, Vol. 66, No. 1, January 2016, pp. 30-36, DOI: http://dx.doi.org/10.14429/dsj.66.8722

  13. Behavioral and plasma monoamine responses to high-speed railway noise stress in mice

    Directory of Open Access Journals (Sweden)

    Guoqing Di

    2013-01-01

    Full Text Available Studies have reported that railway noise causes stress responses. To evaluate the effects of high-speed railway (HSR noise on behaviors and plasma monoamines. Institute of cancer research mice were exposed to previously recorded HSR noise for 53 days. The noise was arranged according to the HSR′s 24-h traffic number and adjusted to a day-night equivalent continuous A-weighted sound pressure level (Ldn of 70 dB (A. The open field test (OFT and the light/dark box test were applied to observe mice behaviors. High performance liquid chromatography-fluorimetric detection was performed to determine the concentrations of plasma norepinephrine (NE, dopamine (DA, serotonin (5-hydroxytryptamine, 5-HT. Data were analyzed by two-way analysis of variance using SPSS 16.0. After 53 days of noise exposure, center time and the frequency of line crossing of the exposed mice decreased significantly in the OFT compared with the control group. Meanwhile, transitions and the time spent in the lit compartment of the exposed group decreased significantly in the light/dark box test. After 40 days of HSR noise exposure, the concentrations of plasma DA of the exposed group were significantly higher than those of the control group, while the plasma NE and 5-HT concentrations showed no significant difference between the two groups. The behavioral tests indicate that 70 dB (A HSR noise can result in anxiety-like behaviors in mice. The physiological results show that plasma DA is more sensitive to HSR noise compared with NE and 5-HT.

  14. Measured and calculated noise reduction of rail dampers and absorption plates on a high speed slab track

    NARCIS (Netherlands)

    Dittrich, M.G.; Graafland, F.; Eisses, A.R.; Nijhof, M.J.J.

    2015-01-01

    Rail dampers and sound absorbing plates have been tested on a high speed railway slab track in a walled cutting at a noise sensitive location. Their noise reduction has been determined from pass-by measurements during service and predicted using BEM calculations. The cutting depth, noise barrier hei

  15. A DFB Fiber Laser Sensor System with Ultra-High Resolution and Its Noise Analysis

    Institute of Scientific and Technical Information of China (English)

    Hao Xiao; Fang Li; Jun He; Yu-Liang Liu

    2008-01-01

    A distributed feedback fiber laser (DFB FL) sensor system with ultra-high resolution is described. The sensor is made by writing distributed feedback structures into a high gain active fiber, and the system employs an unbalanced Michelson interferometer to translate laser wavelength shifts induced by weak measurands into phase shifts. A digital phase generated carrier demodulation scheme is introduced to achieve ultra-high resolution interrogation. A detailed noise analysis of the system is presented, and it is shown that the system resolution is limited by the frequency noise of the DFB FL.

  16. A label-free fluorescence strategy for selective detection of nicotinamide adenine dinucleotide based on a dumbbell-like probe with low background noise.

    Science.gov (United States)

    Chen, Xuexu; Lin, Chunshui; Chen, Yiying; Wang, Yiru; Chen, Xi

    2016-03-15

    In this work we developed a novel label-free fluorescence sensing approach for the detection of nicotinamide adenine dinucleotide (NAD(+)) based on a dumbbell-like DNA probe designed for both ligation reaction and digestion reaction with low background noise. SYBR Green I (SG I), a double-helix dye, was chosen as the readout fluorescence signal. In the absence of NAD(+), the ligation reaction did not occur, but the probe was digested to mononucleotides after the addition of exonuclease I (Exo I) and exonuclease I (Exo III), resulting in a weak fluorescence intensity due to the weak interaction between SG I and mononucleotides. In the presence of NAD(+), the DNA probe was ligated by Escherichia coli DNA ligase, blocking the digestion by Exo I and Exo III. As a result, SG I was intercalated into the stem part of the DNA dumbbell probe and fluorescence enhancement was achieved. This method was simple in design, fast to operate, with good sensitivity and selectivity which could discriminate NAD(+) from its analogs.

  17. Analysis of the Characteristics of the Background Noise from a Nuclear Explosion Monitoring%核爆次声背景噪声信号特征分析

    Institute of Scientific and Technical Information of China (English)

    青建华; 程先友; 庞新良

    2013-01-01

    Infrasound monitoring is one of the four monitoring technologies stipulated in " The Comprehensive Nuclear-Test-Ban Treaty".According to the interest in the understanding of background noise during nuclear explosion infrasound monitoring,the discussion is concentrated on the infrasound caused by earthquake,volcanic eruption,lightning,gale and so on.It's very important to understand these characteristics for developing nuclear explosion infrasound monitoring.%核爆炸次声监测技术是《全面禁止核试验条约》规定的监测技术手段之一,主要用来监测大气层中的核爆炸.根据核爆次声监测对背景噪声信号影响的关注,重点介绍了地震、火山喷发、闪电、大风等非核爆次声信号的特征,了解这些特征对于开展核爆次声监测有益.

  18. 强噪声背景下的微弱信号检测新方法%New Method of Weak Signal Detection with Strong Noise Background

    Institute of Scientific and Technical Information of China (English)

    韦艳冰; 陆绮荣; 黄彬; 高冬美

    2011-01-01

    A new method for weak signal detection with strong noise background is proposed. A scheme which combines hardware with software for realization of this method is designed. In this method, the signals are detected and processed using the classical instrument magnifying technique and single-chip microcomputer control. By means of virtual instrumentation simulation and display, this design provides effective methods to detect μA-level weak signal in pyroelectric infrared detector. Through the experiment of artificial low-frequency weak-signal detection, the system fully reveals its practicality and superiority in the field of weak signal detection.%提出新的强噪声背景下的微弱信号检测方法,设计一种硬件与软件相结合的实现方案.采用经典的仪表放大技术和单片机控制技术对数据进行检测和处理,并通过虚拟仪器技术仿真和显示,为解决热释电红外探测器中μA级微弱信号的检测提供了十分有效的方法.最后通过对模拟低频微弱信号的检测实验,充分显示该系统在微弱信号检测方面的实用性和优越性.

  19. High Dynamic Range RF Front End with Noise Cancellation and Linearization for WiMAX Receivers

    Directory of Open Access Journals (Sweden)

    J.-M. Wu

    2012-06-01

    Full Text Available This research deals with verification of the high dynamic range for a heterodyne radio frequency (RF front end. A 2.6 GHz RF front end is designed and implemented in a hybrid microwave integrated circuit (HMIC for worldwide interoperability for microwave access (WiMAX receivers. The heterodyne RF front end consists of a low-noise amplifier (LNA with noise cancellation, an RF bandpass filter (BPF, a downconverter with linearization, and an intermediate frequency (IF BPF. A noise canceling technique used in the low-noise amplifier eliminates a thermal noise and then reduces the noise figure (NF of the RF front end by 0.9 dB. Use of a downconverter with diode linearizer also compensates for gain compression, which increases the input-referred third-order intercept point (IIP3 of the RF front end by 4.3 dB. The proposed method substantially increases the spurious-free dynamic range (DRf of the RF front end by 3.5 dB.

  20. Attitudes, Values and Background of High School Journalists Compared with the Media Elite.

    Science.gov (United States)

    Johnson, Sammye

    To compare attitudes, values, and background of high school journalists with those of the media elite (journalists already working in the media), a survey was administered to 132 public and private high school students attending the Trinity University Journalism Institute during June 5-9, 1983. These students were the editors of their newspapers,…

  1. Measurement of high-power microwave pulse under intense electromagnetic noise

    Indian Academy of Sciences (India)

    Amitava Roy; S K Singh; R Menon; D Senthil Kumar; R Venkateswaran; M R Kulkarni; P C Saroj; K V Nagesh; K C Mittal; D P Chakravarthy

    2010-01-01

    KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator (VIRCATOR) device. HPM power measurements were carried out using a transmitting–receiving system in the presence of intense high frequency (a few MHz) electromagnetic noise. Initially, the diode detector output signal could not be recorded due to the high noise level persisting in the ambiance. It was found that the HPM pulse can be successfully detected using wide band antenna, RF cable and diode detector set-up in the presence of significant electromagnetic noise. Estimated microwave peak power was ∼ 59.8 dBm (∼ 1 kW) at 7 m distance from the VIRCATOR window. Peak amplitude of the HPM signal varies on shot-to-shot basis. Duration of the HPM pulse (FWHM) also varies from 52 ns to 94 ns for different shots.

  2. An ultra-low noise, high-voltage piezo-driver.

    Science.gov (United States)

    Pisenti, N C; Restelli, A; Reschovsky, B J; Barker, D S; Campbell, G K

    2016-12-01

    We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250 V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switching noise, yielding a total root-mean-square noise of ≈100 μV (1 Hz-100 kHz). A low-voltage (±10 V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both repeatable setpoints and sophisticated control logic, and the circuit consumes less than 150 mA at ±15 V.

  3. An ultra-low noise, high-voltage piezo-driver

    Science.gov (United States)

    Pisenti, N. C.; Restelli, A.; Reschovsky, B. J.; Barker, D. S.; Campbell, G. K.

    2016-12-01

    We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250 V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switching noise, yielding a total root-mean-square noise of ≈100 μV (1 Hz-100 kHz). A low-voltage (±10 V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both repeatable setpoints and sophisticated control logic, and the circuit consumes less than 150 mA at ±15 V.

  4. Automotive Interior Noise Reduction in High Frequency Using Statistical Energy Analysis

    Institute of Scientific and Technical Information of China (English)

    CHEN Xin; WANG Deng-feng; ZHU Lei; MA Zheng-dong

    2009-01-01

    Statistical energy analysis (SEA) is an effective method for predicting high frequency vibro-acoustic performance of automobiles. A full vehicle SEA model is presented for interior noise reduction. It is composed of a number of subsystems based on a 3D model with all parameters for each subsystem. The excitation inputs are measured through road tests in different conditions, including inputs from the engine vibration and the sound pressure of the engine bay. The accuracy in high frequency of SEA model is validated, by comparing the analysis results with the testing pressure level data at driver's right ear. Noise contribution and sensitivity of key subsystems are analyzed. Finally, the effectiveness of noise reduction is verified. Based on the SEA model, an approach combining test and simulation is proposed for the noise vibration and harshness (NVH) design in vehicle development. It contains building the SEA model, testing for subsystem parameter identification, validating the simulation model, identifying subsystem power inputs, analyzing the design sensitivity. An example is given to demonstrate the interior noise reduction in high frequency.

  5. Corona noise model of high-voltage AC transmission lines and engineering applications

    Institute of Scientific and Technical Information of China (English)

    Wu Jiuhui; Di Zelong

    2013-01-01

    In order to predict the levels of corona noise from high-voltage alternating current (AC) transmission lines,the mechanism of corona noise and the corresponding theoretical prediction model are investigated.On the basis of Drude model,the motion of positive and negative ions produced by high-voltage corona is analyzed,and the mechanism of corona noise is discovered.The theoretical prediction model is put forward by using Kirchhoff formula,which is verified by the well agreement between our result and others',considering the case of three-phase single lines.Moreover,the calculation results show that for both single and bundled lines,the sound pressure level of the typical frequency,i.e.twice the power frequency,attenuates slowly and leads to an obviously interferential phenomenon near the transmission lines,but the level of the bundled lines is smaller than that of the single ones under the same transmission voltage.Based on the mechanism of corona noise and the prediction model,it is obvious that bundled lines and/or increased line radius can be adopted to reduce corona noise in the practical engineering applications effectively.This model can also provide a theoretical guidance for the high-volt-age AC transmission line design.

  6. Phase noise measurement of high-power fiber amplifiers

    Institute of Scientific and Technical Information of China (English)

    Hu Xiao; Xiaolin Wang; Yanxing Ma; Bing He; Pu Zhou; Jun Zhou; Xiaojun Xu

    2011-01-01

    We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique. Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density.Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an amplifier, whereas the high frequency components related to laser power affect the control bandwidth. The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9 kHz under the output power of 25,55, 125, and 180W, respectively. The approximately linear relationship between the control bandwidth and laser power needs to be further investigated.%@@ We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique.Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density.Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an am-plifier, whereas the high frequency components related to laser power affect the control bandwidth.The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9kHz under the output power of 25, 55, 125, and 180 W, respectively.The approximately linear relationship between the control bandwidth and laser power needs to be further investigated.

  7. High-frequency hearing thresholds: effects of age, occupational ultrasound and noise exposure.

    Science.gov (United States)

    Maccà, Isabella; Scapellato, Maria Luisa; Carrieri, Mariella; Maso, Stefano; Trevisan, Andrea; Bartolucci, Giovanni Battista

    2015-02-01

    It has been suggested that high-frequency audiometry (HFA) could represent a useful preventive measure in exposed workers. The aim was to investigate the effects of age, ultrasound and noise on high-frequency hearing thresholds. We tested 24 industrial ultrasound-exposed subjects, 113 industrial noise-exposed subjects and 148 non-exposed subjects. Each subject was tested with both conventional-frequency (0.125-8 kHz) and high-frequency (9-18 kHz) audiometry. The hearing threshold at high frequency deteriorated as a function of age, especially in subjects more than 30 years old. The ultrasound-exposed subjects had significantly higher hearing thresholds than the non-exposed ones at the high frequencies, being greatest from 10 to 14 kHz. This hearing loss was already significantly evident in subjects with exposure frequencies 4 and 6 kHz and at the high frequency of 14 kHz. After stratification for age, there was a significant difference between the two groups at 9-10 and 14-15 kHz only for those under 30 years of age. Multivariate analysis indicated that age was the primary predictor, and noise and ultrasound exposure the secondary predictors of hearing thresholds in the high-frequency range. The results suggest that HFA could be useful in the early diagnosis of noise-induced hearing loss in younger groups of workers (under 30 years of age).

  8. Required changes in emission standards for high-frequency noise in power systems

    Energy Technology Data Exchange (ETDEWEB)

    Lundmark, C.M.; Larsson, E.O.A. [Lulea Univ. of Technology, Skelleftea (Sweden); Bollen, M.H.J. [STRI AB, Ludvika (Sweden)

    2006-07-01

    This paper discusses some recent developments that make the existing standards on the emission of high-frequency noise in power systems due for reconsideration. It is shown that it is possible for an equipment to remain below the emission limits while at the same time the disturbance level increases beyond what was intended by the standard document. Further, the change from analog to digital communication and the use of communication via the power system, make that the permitted disturbance levels need to be reconsidered. This paper also contains an example of measured high-frequency noise and proposes a framework for re-coordination of emission and immunity levels. (Author)

  9. Low-frequency suppression of random-telegraph-noise spectra in high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ashkenazy, V.D. (Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)); Jung, G. (Department of Physics, Ben Gurion University of the Negev, 84105 Beer-Sheva (Israel) Instytut Fizuki, Polish Academy of Sciences, 02668 Warszawa (Poland)); Khalfin, I.B. (Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)); Shapiro, B.Y. (Jack and Pearl Resnik Institute of Advanced Technology, Bar-Ilan University, 52100, Ramat Gan (Israel) Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel))

    1995-01-01

    Interaction of the random-telegraph-noise signals with pinned Abrikosov vortices in granular high-temperature superconductors is investigated. It is shown that the low-frequency part of random-noise spectra is suppressed due to interaction of Abrikosov vortices with pinning centers at low magnetic fields and/or due to mutual interactions of vortices in an Abrikosov lattice at high magnetic fields. Values of characteristic frequencies below which spectra are suppressed are evaluated for various experimental configurations including a typical experimental thin-film strip geometry. It is shown that characteristic frequencies and the functional dependence of the low-frequency part of the noise spectra strongly depend on the external magnetic field.

  10. High-power and low-intensity noise laser at 1064  nm.

    Science.gov (United States)

    Guiraud, Germain; Traynor, Nicholas; Santarelli, Giorgio

    2016-09-01

    We have developed a single-frequency, narrow-linewidth (Δνlaser operating at 1064 nm with a high output power (50 W). The laser is based on an ytterbium-doped fiber master oscillator power amplifier architecture with an output beam at the diffraction limit. An output power of 50 W is obtained with two amplification stages using a 50 mW diode laser seeder. We have carefully studied the relative intensity noise at each amplification stage. The detrimental effect due to stimulated Brillouin scattering on residual amplitude noise has been observed on the high-power booster stage. After careful optimization, this laser exhibits low intensity noise with a RMS value equal to 0.012% (1 kHz/10 MHz) at 50 W.

  11. An Analysis of Background Factors of School Non-Attendance in Junior High School Students

    OpenAIRE

    神田,信彦; 大木, 桃代

    2001-01-01

    This study explored the background effect of school non-attendance in junior high school students. Two hundred ninety-eight junior high school students completed a questionaire. It was consist of perceived control scale for children and items about their feelings for parents, classmates, teachers, classes, and so on. The results were as follows:(1)Desire for school non-attendance was controlled with High perceived control, perceived affective support from families and friends, and a feeling o...

  12. Intelligibility of speech in noise at high presentation levels: effects of hearing loss and frequency region.

    Science.gov (United States)

    Summers, Van; Cord, Mary T

    2007-08-01

    These experiments examined how high presentation levels influence speech recognition for high- and low-frequency stimuli in noise. Normally hearing (NH) and hearing-impaired (HI) listeners were tested. In Experiment 1, high- and low-frequency bandwidths yielding 70%-correct word recognition in quiet were determined at levels associated with broadband speech at 75 dB SPL. In Experiment 2, broadband and band-limited sentences (based on passbands measured in Experiment 1) were presented at this level in speech-shaped noise filtered to the same frequency bandwidths as targets. Noise levels were adjusted to produce approximately 30%-correct word recognition. Frequency bandwidths and signal-to-noise ratios supporting criterion performance in Experiment 2 were tested at 75, 87.5, and 100 dB SPL in Experiment 3. Performance tended to decrease as levels increased. For NH listeners, this "rollover" effect was greater for high-frequency and broadband materials than for low-frequency stimuli. For HI listeners, the 75- to 87.5-dB increase improved signal audibility for high-frequency stimuli and rollover was not observed. However, the 87.5- to 100-dB increase produced qualitatively similar results for both groups: scores decreased most for high-frequency stimuli and least for low-frequency materials. Predictions of speech intelligibility by quantitative methods such as the Speech Intelligibility Index may be improved if rollover effects are modeled as frequency dependent.

  13. High pressure air jet in the endoscopic preparation room: risk of noise exposure on occupational health.

    Science.gov (United States)

    Chiu, King-Wah; Lu, Lung-Sheng; Wu, Cheng-Kun

    2015-01-01

    After high-level disinfection of gastrointestinal endoscopes, they are hung to dry in order to prevent residual water droplets impact on patient health. To allow for quick drying and clinical reuse, some endoscopic units use a high pressure air jet (HPAJ) to remove the water droplets on the endoscopes. The purpose of this study was to evaluate the excessive noise exposure with the use of HPAJ in endoscopic preparation room and to investigate the risk to occupational health. Noise assessment was taken during 7 automatic endoscopic reprocessors (AERs) and combined with/without HPAJ use over an 8-hour time-weighted average (TWA). Analytical procedures of the NIOSH and the ISO for noise-induced hearing loss were estimated to develop analytic models. The peak of the noise spectrum of combined HPAJ and 7 AERs was significantly higher than that of the 7 AERs alone (108.3 ± 1.36 versus 69.3 ± 3.93 dBA, P risk of hearing loss (HL > 2.5 dB) was 2.15% at 90 dBA, 11.6% at 95 dBA, and 51.3% at 100 dBA. The odds ratio was 49.1 (95% CI: 11.9 to 203.6). The noise generated by the HPAJ to work over TWA seriously affected the occupational health and safety of those working in an endoscopic preparation room.

  14. Noise levels in an urban Asian school environment.

    Science.gov (United States)

    Chan, Karen M K; Li, Chi Mei; Ma, Estella P M; Yiu, Edwin M L; McPherson, Bradley

    2015-01-01

    Background noise is known to adversely affect speech perception and speech recognition. High levels of background noise in school classrooms may affect student learning, especially for those pupils who are learning in a second language. The current study aimed to determine the noise level and teacher speech-to-noise ratio (SNR) in Hong Kong classrooms. Noise level was measured in 146 occupied classrooms in 37 schools, including kindergartens, primary schools, secondary schools and special schools, in Hong Kong. The mean noise levels in occupied kindergarten, primary school, secondary school and special school classrooms all exceeded recommended maximum noise levels, and noise reduction measures were seldom used in classrooms. The measured SNRs were not optimal and could have adverse implications for student learning and teachers' vocal health. Schools in urban Asian environments are advised to consider noise reduction measures in classrooms to better comply with recommended maximum noise levels for classrooms.

  15. Effects of high-frequency emphasis and compression time constants on speech intelligibility in noise.

    Science.gov (United States)

    van Toor, Thijs; Verschuure, Hans

    2002-10-01

    The objectives of the study were to evaluate the effect of different settings with regard to speech intelligibility in noise both objectively and subjectively and thus determine a favoured setting of compression time parameters, pre-set program (high-frequency emphasis) or combination for each individual user in a prospective study. Another objective was to evaluate the relationship between patient characteristics (e.g. slope of hearing loss) and favoured settings. In total, 38 subjects divided over five audiological centres were fitted with the Philips Spaceline D71-40 BTE digital hearing aid. Subjects were asked to compare three predefined compression algorithms with different time constants, slow (indicated by the manufacturer as AVC), intermediate (NORMAL) and fast (SYLLABIC) over two 4-week periods using the intermediate setting in both comparisons and randomizing over the fast and slow conditions. A randomization determined whether a subject started with the comfort-oriented pre-set program (AUTO) or the speech intelligibility-oriented setting with high-frequency emphasis (SPIN). In a third 4-week period, the pre-sets AUTO and SPIN were compared using the setting of the compression time constants that gave the best results during the first two periods. Comparisons were made using a standard speech-in-noise test with three types of noise: continuous speaker noise, modulated ICRA-4 noise, and car noise. The patients were also asked to fill in a Dutch translation and adaptation of the APHAB questionnaire to indicate their impression of performance. The results indicate that no compression algorithm, pre-set or combination is favoured overall. The largest improvement in speech-in-noise scores was found with syllabic compression. The advantageous effect of high-frequency emphasis after optimization of compression timing is small. The APHAB showed that users tend to prefer the SPIN setting. We found no relationship between favoured compression or pre-set and the

  16. $\\gamma$-Ray Absorption at High Redshifts and the $\\gamma$-Ray Background

    CERN Document Server

    Stecker, F W

    1997-01-01

    We present results of a calculation of absorption of 10-500 GeV gamma-rays at high redshifts. This calculation requires the determination of the high- redshift evolution of the full spectral energy distribution of the intergalactic photon field. For this, we have primarily followed the recent analysis of Fall, Charlot and Pei. We give our results for the gamma-ray opacity as a function of redshift out to a redshift of 3. We then give predicted gamma-ray spectra for selected blazars and also extend our results on the background from unresolved blazars to an energy of 500 GeV. Absorption effects are predicted to significantly steepen the background spectrum above 20 GeV. Our absorption calculations can be used to place limits on the redshifts of gamma-ray bursts. Our background calculations can be used to determine the observability of multi-GeV lines from dark matter neutralino particles.

  17. Design of low noise airfoil with high aerodynamic performance for use on small wind turbines

    Institute of Scientific and Technical Information of China (English)

    Taehyung; KIM; Seungmin; LEE; Hogeon; KIM; Soogab; LEE

    2010-01-01

    Wind power is one of the most reliable renewable energy sources and internationally installed capacity is increasing radically every year.Although wind power has been favored by the public in general,the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased.Low noise wind turbine design is becoming more and more important as noise is spreading more adverse effect of wind turbine to public.This paper demonstrates the design of 10 kW class wind turbines,each of three blades,a rotor diameter 6.4 m,a rated rotating speed 200 r/min and a rated wind speed 10 m/s.The optimized airfoil is dedicated for the 75% spanwise position because the dominant source of a wind turbine blade is trailing edge noise from the outer 25% of the blade.Numerical computations are performed for incompressible flow and for Mach number at 0.145 and for Reynolds numbers at 1.02×106 with a lift performance,which is resistant to surface contamination and turbulence intensity.The objectives in the design process are to reduce noise emission,while sustaining high aerodynamic efficiency.Dominant broadband noise sources are predicted by semi-empirical formulas composed of the groundwork by Brooks et al.and Lowson associated with typical wind turbine operation conditions.During the airfoil redesign process,the aerodynamic performance is analyzed to reduce the wind turbine power loss.The results obtained from the design process show that the design method is capable of designing airfoils with reduced noise using a commercial 10 kW class wind turbine blade airfoil as a basis.Therefore,the new optimized airfoil showing 2.9 dB reductions of total sound pressure level(SPL) and higher aerodynamic performance are achieved.

  18. Designing high-impedance/low-noise superinductances for quantum electronics

    Science.gov (United States)

    Pop, Ioan; Minev, Zlatko; Masluk, Nicholas; Kamal, Archana; Devoret, Michel

    2012-02-01

    Superinductances are essential circuit elements which enable the suppression of charge fluctuations in superconducting fluxonium qubits [1] and in other Josephson junction devices [2]. Commonly implemented as an array of Josephson junctions, superinductances have two main limitations. Firstly, the spurious capacitive coupling of the chain islands to ground lowers the plasma frequency of the chain, and consequently limits the operational bandwidth. Secondly, coherent quantum phase-slips (CQPS) [3] in the Josephson junction chain induce time dependent inductance fluctuations via the Aharonov-Casher effect [4]. We present the application of a novel lithographic technique [5] which enables the fabrication of arrays with optimal junction-capacitance to ground-capacitance ratio. We also present new superinductance designs which topologically suppress the CQPS, allowing the implementation of practically phase-slip free high inductance Josephson junction.[4pt] [1] Manucharyan et al., Science, 326 (2009)[0pt] [2] Guichard and Hekking, PRB, 81 (2010)[0pt] [3] Matveev et al. PRL, 89 (2002)[0pt] [4] Pop et al., arXiv:1105.6204 and Manucharyan et al., arXiv:1012.1928[0pt] [5] Lecocq et al., Nanotechnology, 22 (2011)

  19. High-Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement

    Science.gov (United States)

    Quackenbush, Todd R.; McKillip, Robert M., Jr.

    2011-01-01

    One of key NASA goals is to develop and integrate noise reduction technology to enable unrestricted air transportation service to all communities. One of the technical priorities of this activity has been to account for and reduce noise via propulsion/airframe interactions, identifying advanced concepts to be integrated with the airframe to mitigate these noise-producing mechanisms. An adaptive geometry chevron using embedded smart structures technology offers the possibility of maximizing engine performance while retaining and possibly enhancing the favorable noise characteristics of current designs. New high-temperature shape memory alloy (HTSMA) materials technology enables the devices to operate in both low-temperature (fan) and high-temperature (core) exhaust flows. Chevron-equipped engines have demonstrated reduced noise in testing and operational use. It is desirable to have the noise benefits of chevrons in takeoff/landing conditions, but have them deployed into a minimum drag position for cruise flight. The central feature of the innovation was building on rapidly maturing HTSMA technology to implement a next-generation aircraft noise mitigation system centered on adaptive chevron flow control surfaces. In general, SMA-actuated devices have the potential to enhance the demonstrated noise reduction effectiveness of chevron systems while eliminating the associated performance penalty. The use of structurally integrated smart devices will minimize the mechanical and subsystem complexity of this implementation. The central innovations of the effort entail the modification of prior chevron designs to include a small cut that relaxes structural stiffness without compromising the desired flow characteristics over the surface; the reorientation of SMA actuation devices to apply forces to deflect the chevron tip, exploiting this relaxed stiffness; and the use of high-temperature SMA (HTSMA) materials to enable operation in the demanding core chevron environment

  20. Turbulent Flow Physics and Noise in High Reynolds Number Compressible Jets

    Science.gov (United States)

    Glauser, Mark

    2016-11-01

    In this talk I will present a snapshot of our ongoing research in high Reynolds number turbulent compressible jets. The high speed axisymmetric jet work (Mach 0.6 - 1.1) has been jointly performed with Spectral Energies LLC through AFRL support and involves 10 kHz and large window PIV data extracted from the near field jet plume, simultaneously sampled with near field pressure and far field noise. We have learned from the simultaneously sampled 10 kHz PIV near field plume and far field noise data, using POD/OID and Wavelet filtering, that there are certain "loud" velocity modes that have low averaged turbulent kinetic energy content but strongly correlate with the far field noise. From the large window PIV data obtained at Mach 1.0 and 1.1, specific POD modes were found to contain important physics of the problem. For example, the large-scale structure of the jet, shock-related fluctuations, and turbulent mixing regions of the flow were isolated through POD. By computing cross correlations, particular POD modes were found to be related to particular noise spectra. I will conclude with a description of our complex nozzle work which uses the multi-stream supersonic single expansion rectangular nozzle (SERN) recently installed in our large anechoic chamber at SU. This work is funded from both AFOSR (joint with OSU with a primary focus on flow physics) and Spectral Energies LLC (via AFRL funds with a focus on noise). Particular emphasis will be on insight gained into this complex 3D flow field (and its relationship to the far field noise) from applications of POD, Wavelet filtering and DMD to various numerical (LES) and experimental (PIV, high speed schlieren, near and far field pressure) data sets, at a core nozzle Mach number of 1.6 and a second stream Mach number of 1.0.

  1. Discrimination against Students with Foreign Backgrounds: Evidence from Grading in Swedish Public High Schools

    Science.gov (United States)

    Hinnerich, Bjorn Tyrefors; Höglin, Erik; Johannesson, Magnus

    2015-01-01

    We rigorously test for discrimination against students with foreign backgrounds in high school grading in Sweden. We analyse a random sample of national tests in the Swedish language graded both non-blindly by the student's own teacher and blindly without any identifying information. The increase in the test score due to non-blind grading is…

  2. High-resolution varve studies in Baldeggersee (Switzerland): Project overview and limnological background data

    NARCIS (Netherlands)

    Wehrli, B.; Lotter, A.F.; Schaller, T.; Sturm, M.

    1997-01-01

    This introduction to a series of high-resolution varve studies in Baldeggersee provides both an overview of the different subprojects as well as background information on relevant limnologial trends. The project was based on a new method of in-situ freezing of unconsolidated surficial

  3. Discrimination against Students with Foreign Backgrounds: Evidence from Grading in Swedish Public High Schools

    Science.gov (United States)

    Hinnerich, Bjorn Tyrefors; Höglin, Erik; Johannesson, Magnus

    2015-01-01

    We rigorously test for discrimination against students with foreign backgrounds in high school grading in Sweden. We analyse a random sample of national tests in the Swedish language graded both non-blindly by the student's own teacher and blindly without any identifying information. The increase in the test score due to non-blind grading is…

  4. The Capacity of Finite-State Channels in the High-Noise Regime

    CERN Document Server

    Pfister, Henry D

    2010-01-01

    This paper considers the derivative of the entropy rate of a hidden Markov process with respect to the observation probabilities. The main result is a compact formula for the derivative that can be evaluated easily using Monte Carlo methods. It is applied to the problem of computing the capacity of a finite-state channel (FSC) and, in the high-noise regime, the formula has a simple closed-form expression that enables series expansion of the capacity of a FSC. This expansion is evaluated for a binary-symmetric channel under a (0,1) run-length limited constraint and an intersymbol-interference channel with Gaussian noise.

  5. High levels of sound pressure: acoustic reflex thresholds and auditory complaints of workers with noise exposure

    Directory of Open Access Journals (Sweden)

    Alexandre Scalli Mathias Duarte

    2015-08-01

    Full Text Available INTRODUCTION: The clinical evaluation of subjects with occupational noise exposure has been difficult due to the discrepancy between auditory complaints and auditory test results. This study aimed to evaluate the contralateral acoustic reflex thresholds of workers exposed to high levels of noise, and to compare these results to the subjects' auditory complaints.METHODS: This clinical retrospective study evaluated 364 workers between 1998 and 2005; their contralateral acoustic reflexes were compared to auditory complaints, age, and noise exposure time by chi-squared, Fisher's, and Spearman's tests.RESULTS: The workers' age ranged from 18 to 50 years (mean = 39.6, and noise exposure time from one to 38 years (mean = 17.3. We found that 15.1% (55 of the workers had bilateral hearing loss, 38.5% (140 had bilateral tinnitus, 52.8% (192 had abnormal sensitivity to loud sounds, and 47.2% (172 had speech recognition impairment. The variables hearing loss, speech recognition impairment, tinnitus, age group, and noise exposure time did not show relationship with acoustic reflex thresholds; however, all complaints demonstrated a statistically significant relationship with Metz recruitment at 3000 and 4000 Hz bilaterally.CONCLUSION: There was no significance relationship between auditory complaints and acoustic reflexes.

  6. Distribution of background equivalent static wind load on high-rise buildings

    Institute of Scientific and Technical Information of China (English)

    Jianguo ZHANG; Ming GU

    2009-01-01

    In this paper, the along-wind and cross-wind fluctuating load distributions along the height of high-rise buildings and their correlations are obtained through simultaneous pressure measurements in a wind tunnel.Some typical methods proposed in some relative litera-tures, i.e., load-response correlation (LRC), and quasi-mean load (QML) and gust load envelope (GLE) methods,are verified in terms of their accuracy in describing the background equivalent static wind load distribution on high-rise buildings. Based on the results, formulae of the distribution of background equivalent static load on high-rise buildings with typical shapes are put forward. It is shown that these formulae are of high accuracy and practical use.

  7. High Degree Cubature Federated Filter for Multisensor Information Fusion with Correlated Noises

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    2016-01-01

    Full Text Available This paper proposes an improved high degree cubature federated filter for the nonlinear fusion system with cross-correlation between process and measurement noises at the same time using the fifth-degree cubature rule and the decorrelated principle in its local filters. The master filter of the federated filter adopts the no-reset mode to fuse local estimates of local filters to generate a global estimate according to the scalar weighted rule. The air-traffic maneuvering target tracking simulations are performed between the proposed filter and the fifth-degree cubature federated filter. Simulations results demonstrate that the proposed filter not only can achieve almost the same accuracy as the fifth-degree cubature federated filter with independent white noises, but also has superior performance to the fifth-degree cubature federated filter while the noises are cross-correlated at the same time.

  8. An integrated low 1/f noise and high-sensitivity CMOS instrumentation amplifier for TMR sensors

    Science.gov (United States)

    Gao, Zhiqiang; Luan, Bo; Zhao, Jincai; Liu, Xiaowei

    2017-03-01

    In this paper, a very low 1/f noise integrated Wheatstone bridge magnetoresistive sensor ASIC based on magnetic tunnel junction (MTJ) technology is presented for high sensitivity measurements. The present CMOS instrumentation amplifier employs the gain-boost folded-cascode structure based on the capacitive-feedback chopper-stabilized technique. By chopping both the input and the output of the amplifier, combined with MTJ magnetoresistive sensitive elements, a noise equivalent magnetoresistance 1 nT/Hz1/2 at 2 Hz, the equivalent input noise spectral density 17 nV/Hz1/2(@2Hz) is achieved. The chip-scale package of the TMR sensor and the instrumentation amplifier is only about 5 mm × 5 mm × 1 mm, while the whole DC current dissipates only 2 mA.

  9. Beyond noise: using temporal ICA to extract meaningful information from high-frequency fMRI signal fluctuations during rest

    Directory of Open Access Journals (Sweden)

    Roland Norbert Boubela

    2013-05-01

    Full Text Available Analysis of resting-state networks using fMRI usually ignores high-frequencyfluctuations in the BOLD signal – be it because of low TR prohibiting the analysis offluctuations with frequencies higher than 0.25 Hz (for a typical TR of 2 s, or becauseof the application of a bandpass filter (commonly restricting the signal to frequencieslower than 0.1 Hz. While the standard model of convolving neuronal activity with ahemodynamic response function suggests that the signal of interest in fMRI is characterized by slow fluctuation, it is in fact unclear whether the high-frequency dynamics of the signal consists of noise only. In this study, 10 subjects were scanned at 3 T during 6 minutes of rest using a multiband EPI sequence with a TR of 354 ms to critically sample fluctuations of up to 1.4 Hz. Preprocessed data were high-pass filtered to include only frequencies above 0.25 Hz, and voxelwise whole-brain temporal ICA (tICA was used to identify consistent high-frequency signals. The resulting components include physiological background signal sources, most notably pulsation and heartbeat components, that can be specifically identified and localized with the method presented here. Perhaps more surprisingly, common resting-state networks like the default-mode network also emerge as separate tICA components. This means that high frequency oscillations sampled with a rather T1-weighted contrast still contain specific information on these resting-state networks to consistently identify them, not consistent with the commonly held view that these networks operate on low-frequency fluctuations alone. Consequently, the use of bandpass filters in resting-state data analysis should be reconsidered, since this step eliminates potentially relevant information. Instead, more specific methods for the elimination of physiological background signals, for example by regression of physiological noise components, might prove to be viable alternatives.

  10. Low-frequency noise in high-{Tc} superconductor Josephson junctions, SQUIDs, and magnetometers

    Energy Technology Data Exchange (ETDEWEB)

    Miklich, A.H.

    1994-05-01

    Design and performance of high-T{sub c} dc superconducting quantum interference devices (SQUEDs), junctions that comprise them, and magnetometers made from them are described, with attention to sources of 1/f noise. Biepitaxial junctions are found to have large levels of critical current fluctuations which make them unsuitable for low-noise SQUIDS; this suggests a poorly connected interface at the grain boundary junction. SQUIDs from bicrystal junctions have levels of critical current noise controllable using bias current reversal techniques which leave the noise white down to frequencies of a few Hz. A SQUID with an energy resolution of 1.5{times}10{sup {minus}30} J Hz{sup {minus}1} at 1 Hz is reported. Magnetometers in which a (9 mm){sup 2} pickup loop is directly coupled to a SQUID body have achieved field resolutions of 93 fT Hz{sup {minus}1/2} down to frequencies below I Hz, improving to 39 fT Hz{sup {minus}1/2} at 1 Hz with the addition of a 50mm-diameter single-turn flux transformer. Poor coupling to pickup loop makes it difficult to satisfy competing goals of high field resolution and small detector size necessary for multichannel biomagnetic imaging. Improved coupling is demonstrated by the use of multiturn-input-coil flux transformers, and a resolution of 35 fT Hz{sup {minus}1/2} in the white noise region is reported with a (10 mm){sup 2} pickup loop. However, additional 1/f noise from processed multilayer structures in the transformer limits the resolution at 1 Hz to 114 fT Hz{sup {minus}1/2}. High-T{sub c} SQUIDs exhibit additional 1/f noise when cooled in a nonzero static magnetic field because of additional flux vortices trapped in the film, with the noise power at 1 Hz typically increasing by a factor of 10--20 in a field of 0.05mT (0.5 G). Finally, a SQUID-based voltmeter with a resolution of 9.2 pV.Hz{sup {minus}1/2} at 10 Hz (24 pV Hz{sup {minus}1/2} at 1 Hz) is described.

  11. Highly-efficient noise-assisted energy transport in classical oscillator systems

    CERN Document Server

    León-Montiel, R de J

    2013-01-01

    Photosynthesis is a biological process that involves the highly-efficient transport of energy captured from the sun to a reaction center, where conversion into useful biochemical energy takes place. Even though one can always use a quantum perspective to describe any physical process, since everything follows the laws of Quantum Mechanics, is the use of quantum theory imperative to explain this high efficiency? Several theoretical studies suggest that the high efficiency can only be understood as a result of the interplay between the quantum coherent evolution of the photosynthetic system, and noise introduced by its surrounding environment. Notwithstanding, we show here that noise-assisted highly-efficient energy transport can be found as well in purely classical systems; therefore, we might conclude that high efficiency energy transfer in photosynthetic systems could also be anticipated by classical models, without the need to resorting to quantum effects. Strikingly, the wider scope of applicability of the...

  12. Low noise and high CMRR front-end amplifier dedicated to portable EEG acquisition system.

    Science.gov (United States)

    Chebli, Robert; Sawan, Mohamad

    2013-01-01

    This paper concerns the design and implementation of a fully integrated low noise and high CMRR rail-to-rail preamplifier dedicated to EEG acquisition channel. The preamplification technique is based on two complementary CMOS True Logarithmic Amplifier (TLA) stages connected in parallel. The TLA largely amplifies small amplitude of EEG signals, and moderately the large amplitude ones created during epileptic. A chopper stabilization technique is used to filter the 1/ƒ noise and the DC offset voltage of the input CMOS transistors and to increase the common-mode rejection ratio (CMRR). Due to the TLA structure, a high CMRR and high power supply rejection ratio are achieved and the signal-to-noise ratio (of the channel is better enhanced). To snugly fit the ADC input window to the EEG signal magnitude a new programming gain approach is implemented. Also, a chopper spike filter is used to cancel the spike voltages generated by the charge injections of modulator/demodulator switches. The proposed preamplifier is implemented in 0.18 µm CMOS technology. Post-layout simulation results exhibit 253 dB @50/60 Hz as CMRR, 500 nVrms @100 Hz as input-referred noise while consuming 55 µA from a 1.8 V supply.

  13. Improvement in Background Error Covariances Using Ensemble Forecasts for Assimilation of High-Resolution Satellite Data

    Institute of Scientific and Technical Information of China (English)

    Seung-Woo LEE; Dong-Kyou LEE

    2011-01-01

    Satellite data obtained over synoptic data-sparse regions such as an ocean contribute toward improving the quality of the initial state of limited-area models. Background error covariances are crucial to the proper distribution of satellite-observed information in variational data assimilation. In the NMC (National Meteorological Center) method, background error covariances are underestimated over data-sparse regions such as an ocean because of small differences between different forecast times. Thus, it is necessary to reconstruct and tune the background error covariances so as to maximize the usefulness of the satellite data for the initial state of limited-area models, especially over an ocean where there is a lack of conventional data.In this study, we attempted to estimate background error covariances so as to provide adequate error statistics for data-sparse regions by using ensemble forecasts of optimal perturbations using bred vectors.The background error covariances estimated by the ensemble method reduced the overestimation of error amplitude obtained by the NMC method. By employing an appropriate horizontal length scale to exclude spurious correlations, the ensemble method produced better results than the NMC method in the assimilation of retrieved satellite data. Because the ensemble method distributes observed information over a limited local area, it would be more useful in the analysis of high-resolution satellite data. Accordingly, the performance of forecast models can be improved over the area where the satellite data are assimilated.

  14. Fluctuations in the High-Redshift Lyman-Werner and Lyman-alpha Radiation Backgrounds

    CERN Document Server

    Holzbauer, Lauren N

    2011-01-01

    We use a new method to model fluctuations of the Lyman-Werner (LW) and Lyman-alpha radiation backgrounds at high redshift. At these early epochs the backgrounds are symptoms of a universe newly lit with its first stars. LW photons (11.5-13.6 eV) are of particular interest because they dissociate molecular hydrogen, the primary coolant in the first minihalos. By using a variation of the halo model, we efficiently generate power spectra for any choice of radiation background. We find that the LW power spectrum typically traces the matter power spectrum at large scales but turns over at the scale corresponding to the effective `horizon' of LW photons (~100 comoving Mpc), unless the sources are extremely rare. The series of horizons that characterize the Lyman-alpha flux profile shape the fluctuations of that background in a similar fashion, though those imprints are washed out once one considers fluctuations in the brightness temperature of the 21-cm signal. The Lyman-alpha background strongly affects the redshi...

  15. Development of Low-Noise High Value Chromium Silicide Resistors for Cryogenic Detector Applications

    Science.gov (United States)

    Jhabvala, Murzy; Babu, Sachi; Monroy, Carlos; Darren, C.; Krebs, Carolyn A. (Technical Monitor)

    2001-01-01

    Extremely high sensitivity detectors, such as silicon bolometers are required in many NASA missions for detection of photons from the x-ray to the far infrared regions. Typically, these detectors are cooled to well below the liquid helium (LHe) temperature (4.2 K) to achieve the maximum detection performance. As photoconductors, they are generally operated with a load resistor and a pre-set bias voltage, which is then coupled to the input gate of a source-follower Field Effect Transistor (FET) circuit. It is imperative that the detector system signal to noise performance be limited by the noise of the detector and not by the noise of the external components. The load resistor value is selected to optimize the detector performance. These two criteria tend to be contradictory in that these detectors require load resistors in the hundreds of megaohms, which leads to a higher Johnson noise. Additionally, the physical size of the resistor must be small for device integration as required by such missions as the NASA High Resolution Airborne Wide-Band Camera (HAWC) instrument and the Submillimeter High Angular Resolution Camera (SHARC) for the Caltech Submillimeter Observatory (CSO). We have designed, fabricated and characterized thin film resistors using a CrSi/TiW/Al metal system on optical quality quartz substrates. The resistor values range from 100 megaohms to over 650 megaohms and are Johnson noise limited at LHe temperatures. The resistor film is sputtered with a sheet resistance ranging from 300 ohms to 1600 ohms and the processing sequence developed for these devices allows for chemically fine tuning the sheet resistance in-situ. The wafer fabrication process was of sufficiently high yield (>80%) providing clusters of good resistors for integrated multiple detector channels, a very important feature in the assembly of these two instruments.

  16. High temporal resolution mapping of seismic noise sources using heterogeneous supercomputers

    Science.gov (United States)

    Gokhberg, Alexey; Ermert, Laura; Paitz, Patrick; Fichtner, Andreas

    2017-04-01

    Time- and space-dependent distribution of seismic noise sources is becoming a key ingredient of modern real-time monitoring of various geo-systems. Significant interest in seismic noise source maps with high temporal resolution (days) is expected to come from a number of domains, including natural resources exploration, analysis of active earthquake fault zones and volcanoes, as well as geothermal and hydrocarbon reservoir monitoring. Currently, knowledge of noise sources is insufficient for high-resolution subsurface monitoring applications. Near-real-time seismic data, as well as advanced imaging methods to constrain seismic noise sources have recently become available. These methods are based on the massive cross-correlation of seismic noise records from all available seismic stations in the region of interest and are therefore very computationally intensive. Heterogeneous massively parallel supercomputing systems introduced in the recent years combine conventional multi-core CPU with GPU accelerators and provide an opportunity for manifold increase and computing performance. Therefore, these systems represent an efficient platform for implementation of a noise source mapping solution. We present the first results of an ongoing research project conducted in collaboration with the Swiss National Supercomputing Centre (CSCS). The project aims at building a service that provides seismic noise source maps for Central Europe with high temporal resolution (days to few weeks depending on frequency and data availability). The service is hosted on the CSCS computing infrastructure; all computationally intensive processing is performed on the massively parallel heterogeneous supercomputer "Piz Daint". The solution architecture is based on the Application-as-a-Service concept in order to provide the interested external researchers the regular access to the noise source maps. The solution architecture includes the following sub-systems: (1) data acquisition responsible for

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

    Science.gov (United States)

    Wang, K.; Luo, Y.; Yang, Y.

    2016-12-01

    with results from geology surveys than those based on uncorrected ones. As ambient noise in high frequency band (>1Hz) is mostly related to human activities or climate events, both of which have strong directivity, the iterative approach demonstrated here helps improve the accuracy and resolution of ANT in imaging shallow earth structures.

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

    Science.gov (United States)

    Wang, Kai; Luo, Yinhe; Yang, Yingjie

    2016-05-01

    corrected interstation dispersion measurements are more consistent with results from geology surveys than those based on uncorrected data. As ambient noise in high-frequency band (>1 Hz) is mostly related to human activities or climate events, both of which have strong directivity, the iterative approach demonstrated here helps improve the accuracy and resolution of ANT in imaging shallow earth structures.

  19. An extremely simple method for fabricating 3D protein microarrays with an anti-fouling background and high protein capacity.

    Science.gov (United States)

    Lin, Zhifeng; Ma, Yuhong; Zhao, Changwen; Chen, Ruichao; Zhu, Xing; Zhang, Lihua; Yan, Xu; Yang, Wantai

    2014-07-21

    Protein microarrays have become vital tools for various applications in biomedicine and bio-analysis during the past decade. The intense requirements for a lower detection limit and industrialization in this area have resulted in a persistent pursuit to fabricate protein microarrays with a low background and high signal intensity via simple methods. Here, we report on an extremely simple strategy to create three-dimensional (3D) protein microarrays with an anti-fouling background and a high protein capacity by photo-induced surface sequential controlled/living graft polymerization developed in our lab. According to this strategy, "dormant" groups of isopropyl thioxanthone semipinacol (ITXSP) were first introduced to a polymeric substrate through ultraviolet (UV)-induced surface abstraction of hydrogen, followed by a coupling reaction. Under visible light irradiation, the ITXSP groups were photolyzed to initiate surface living graft polymerization of poly(ethylene glycol) methyl methacrylate (PEGMMA), thus introducing PEG brushes to the substrate to generate a full anti-fouling background. Due to the living nature of this graft polymerization, there were still ITXSP groups on the chain ends of the PEG brushes. Therefore, by in situ secondary living graft cross-linking copolymerization of glycidyl methacrylate (GMA) and polyethylene glycol diacrylate (PEGDA), we could finally plant height-controllable cylinder microarrays of a 3D PEG network containing reactive epoxy groups onto the PEG brushes. Through a commonly used reaction of amine and epoxy groups, the proteins could readily be covalently immobilized onto the microarrays. This delicate design aims to overcome two universal limitations in protein microarrays: a full anti-fouling background can effectively eliminate noise caused by non-specific absorption and a 3D reactive network provides a larger protein-loading capacity to improve signal intensity. The results of non-specific protein absorption tests

  20. High finesse external cavity VCSELs: from very low noise lasers to dual frequency lasers

    Science.gov (United States)

    Baili, Ghaya; Alouini, Medhi; Morvan, Loic; Bretenaker, Fabien; Sagnes, Isabelle; Garnache, Arnaud; Dolfi, Daniel

    2011-01-01

    Low noise-level optical sources are required for numerous applications such as microwave photonics, fiber-optic sensing and time/frequency references distribution. In this paper, we demonstrate how inserting a SC active medium into a centimetric high-Q external cavity is a simple way to obtain a shot-noise-limited laser source over a very wide frequency bandwidth. This approach ensures, with a compact design, a sufficiently long photon lifetime to reach the oscillation-relaxation- free class-A regime. This concept has been illustrated by inserting a 1/2-VCSEL in an external cavity including an etalon filter. A -156dB/Hz relative intensity noise level is obtained over the 100 MHz to 18 GHz bandwidth of interest. This is several orders of magnitude better than the noise, previously observed in VCSELs, belonging to the class-B regime. The optimization, in terms of noise, is shown to be a trade-off between the cavity length and the laser mode filtering. The transition between the class-B and class-A dynamical behaviors is directly observed by continuously controlling the photon lifetime is a sub-millimetric to a centimetric cavity length. It's proven that the transition occurs progressively, without any discontinuity. Based on the same laser architecture, tunable dual-frequency oscillation is demonstrated by reducing the polarized eigenstates overlap in the gain medium. The class-A dynamics of such a laser, free of relaxation oscillations, enables to suppress the electrical phase noise in excess, usually observed in the vicinity of the beat note. An original technique for jitter reduction in mode-locked VECSELs is also investigated. Such lasers are needed for photonic analog to digital converters.

  1. High-frequency audiometry: a means for early diagnosis of noise-induced hearing loss.

    Science.gov (United States)

    Mehrparvar, Amir H; Mirmohammadi, Seyyed J; Ghoreyshi, Abbas; Mollasadeghi, Abolfazl; Loukzadeh, Ziba

    2011-01-01

    Noise-induced hearing loss (NIHL), an irreversible disorder, is a common problem in industrial settings. Early diagnosis of NIHL can help prevent the progression of hearing loss, especially in speech frequencies. For early diagnosis of NIHL, audiometry is performed routinely in conventional frequencies. We designed this study to compare the effect of noise on high-frequency audiometry (HFA) and conventional audiometry. In a historical cohort study, we compared hearing threshold and prevalence of hearing loss in conventional and high frequencies of audiometry among textile workers divided into two groups: With and without exposure to noise more than 85 dB. The highest hearing threshold was observed at 4000 Hz, 6000 Hz and 16000 Hz in conventional right ear audiometry, conventional left ear audiometry and HFA in each ear, respectively. The hearing threshold was significantly higher at 16000 Hz compared to 4000. Hearing loss was more common in HFA than conventional audiometry. HFA is more sensitive to detect NIHL than conventional audiometry. It can be useful for early diagnosis of hearing sensitivity to noise, and thus preventing hearing loss in lower frequencies especially speech frequencies.

  2. High Resolution DOA Estimation Using Unwrapped Phase Information of MUSIC-Based Noise Subspace

    Science.gov (United States)

    Ichige, Koichi; Saito, Kazuhiko; Arai, Hiroyuki

    This paper presents a high resolution Direction-Of-Arrival (DOA) estimation method using unwrapped phase information of MUSIC-based noise subspace. Superresolution DOA estimation methods such as MUSIC, Root-MUSIC and ESPRIT methods are paid great attention because of their brilliant properties in estimating DOAs of incident signals. Those methods achieve high accuracy in estimating DOAs in a good propagation environment, but would fail to estimate DOAs in severe environments like low Signal-to-Noise Ratio (SNR), small number of snapshots, or when incident waves are coming from close angles. In MUSIC method, its spectrum is calculated based on the absolute value of the inner product between array response and noise eigenvectors, means that MUSIC employs only the amplitude characteristics and does not use any phase characteristics. Recalling that phase characteristics plays an important role in signal and image processing, we expect that DOA estimation accuracy could be further improved using phase information in addition to MUSIC spectrum. This paper develops a procedure to obtain an accurate spectrum for DOA estimation using unwrapped and differentiated phase information of MUSIC-based noise subspace. Performance of the proposed method is evaluated through computer simulation in comparison with some conventional estimation methods.

  3. Designing acoustics for linguistically diverse classrooms: Effects of background noise, reverberation and talker foreign accent on speech comprehension by native and non-native English-speaking listeners

    Science.gov (United States)

    Peng, Zhao Ellen

    The current classroom acoustics standard (ANSI S12.60-2010) recommends core learning spaces not to exceed background noise level (BNL) of 35 dBA and reverberation time (RT) of 0.6 second, based on speech intelligibility performance mainly by the native English-speaking population. Existing literature has not correlated these recommended values well with student learning outcomes. With a growing population of non-native English speakers in American classrooms, the special needs for perceiving degraded speech among non-native listeners, either due to realistic room acoustics or talker foreign accent, have not been addressed in the current standard. This research seeks to investigate the effects of BNL and RT on the comprehension of English speech from native English and native Mandarin Chinese talkers as perceived by native and non-native English listeners, and to provide acoustic design guidelines to supplement the existing standard. This dissertation presents two studies on the effects of RT and BNL on more realistic classroom learning experiences. How do native and non-native English-speaking listeners perform on speech comprehension tasks under adverse acoustic conditions, if the English speech is produced by talkers of native English (Study 1) versus native Mandarin Chinese (Study 2)? Speech comprehension materials were played back in a listening chamber to individual listeners: native and non-native English-speaking in Study 1; native English, native Mandarin Chinese, and other non-native English-speaking in Study 2. Each listener was screened for baseline English proficiency level, and completed dual tasks simultaneously involving speech comprehension and adaptive dot-tracing under 15 acoustic conditions, comprised of three BNL conditions (RC-30, 40, and 50) and five RT scenarios (0.4 to 1.2 seconds). The results show that BNL and RT negatively affect both objective performance and subjective perception of speech comprehension, more severely for non

  4. Low-Noise Free-Running High-Rate Photon-Counting for Space Communication and Ranging

    Science.gov (United States)

    Lu, Wei; Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Merritt, Scott

    2016-01-01

    We present performance data for low-noise free-running high-rate photon counting method for space optical communication and ranging. NASA GSFC is testing the performance of two types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We successfully measured real-time communication performance using both the 2 detected-photon threshold and logic AND-gate coincidence methods. Use of these methods allows mitigation of dark count, after-pulsing and background noise effects without using other method of Time Gating The HgCdTe APD array routinely demonstrated very high photon detection efficiencies (50) at near infrared wavelength. The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output. NASA GSFC has tested both detectors for their potential application for space communications and ranging. We developed and compare their performances using both the 2 detected photon threshold and coincidence methods.

  5. Application of sound intensity and partial coherence to identify interior noise sources on the high speed train

    Science.gov (United States)

    Fan, Rongping; Su, Zhongqing; Meng, Guang; He, Caichun

    2014-06-01

    In order to provide a quieter riding environment for passengers, sound quality refinement of rail vehicle is a hot issue. Identification of interior noise sources is the prerequisite condition to reduce the interior noise on high speed train. By considering contribution of noise sources such as rolling noise, mechanical equipment noise, structure-borne noise radiated by car body vibration to the interior noise, the synthesized measurement of sound intensity, sound pressure levels and vibration have been carried out in four different carriages on high speed train. The sound intensity and partial coherence methods have been used to identify the most significant interior noise sources. The statistical analysis results of sound intensity near window and floor on four carriages indicate that sound intensity near floor is higher than that near window at three traveling speeds. Ordinary and partial coherent analysis of vibro-acoustical signals show that the major internal noise source is structural-borne sound radiated by floor vibration. These findings can be utilized to facilitate the reduction of interior noise in the future.

  6. 高速列车透射噪声与结构噪声的分离%High speed train transmission noise and structural noise separation

    Institute of Scientific and Technical Information of China (English)

    纳跃跃; 谢翀

    2013-01-01

    高速列车噪声是影响车内旅客舒适度和铁路沿线居民生活质量的重要因素,如何有效的降低噪声是高速列车设计者们所关心的问题之一.研究表明,高速列车的车内噪声由透射噪声与结构噪声组成,如何有效的从车内噪声中分离出这两种噪声成分将为列车的减振降噪设计提供一定的指导作用.本文以高速列车实车噪声数据为研究对象,首先运用多种数字信号处理的方法对高速列车噪声数据进行了分析,总结了高速列车噪声的主要特点;然后通过对列车静止时和运行时的噪声透射情形分别进行建模和分析,指出可以利用车体的频响特性作为反映车体隔声性能的声学参数,并提出了一种计算频响特性的简便算法;最后,利用该算法从实车噪声数据中计算出了车体的频响特性,并在此基础上实现了透射噪声与结构噪声的分离.%High speed train noise level is an important factor with respect to passenger comfort and life quality of residents along the railway.How to attenuate the noise level is an important research direction that train designers care about.Studies show that train interior noise is consist of transmission noise and structural noise.Separating these two kinds of components from their overall observations will provide further guide to high speed train noise reduction design.The research is based on the real-world high speed train noise data.First,data are analyzed by different digital signal processing methods and some basic properties of the train noise signal are concluded.Then,by modeling and analyzing the noise transmission circumstances when train is stationary and moving,train body frequency response is used to measure the noise insulation quality,and an algorithm is proposed to calculate the frequency response conveniently.At last,train body frequency response is calculated according to the real-world train noise data via the proposed algorithm

  7. High critical temperature superconducting quantum interference device magnetometer with feedforward active noise control system for magnetocardiographic measurement in unshielded circumstances

    Energy Technology Data Exchange (ETDEWEB)

    Mizukami, A.; Nishiura, H.; Sakuta, K.; Kobayashi, T

    2003-10-15

    Magnetocardiographic (MCG) measurement in unshielded environment for practical use requires to suppress the environmental magnetic noise. We have designed the high critical temperature superconducting quantum interference device (High-T{sub c} SQUID) magnetometer with feedforward active noise control (ANC) system to suppress the environmental magnetic noise. The compensatory system consisted of two SQUID magnetometers, a digital signal processor (DSP) and the coil wound around the input magnetometer. The DSP calculated the output data to minimize the environmental noise from the input and reference date and then the coil generated the magnetic field to cancel the environmental noise. This method achieved the effective noise attenuation below 100 Hz about 40 dB. MCG measurement in unshielded environment was also performed.

  8. Effect of high energy electron irradiation on low frequency noise in 4H-SiC Schottky diodes

    Science.gov (United States)

    Kozlovski, V. V.; Lebedev, A. A.; Levinshtein, M. E.; Rumyantsev, S. L.; Palmour, J. W.

    2017-03-01

    The low-frequency noise in high voltage Ni/4H-SiC Schottky diodes irradiated with high energy (0.9 MeV) electrons was studied in the frequency range from 1 Hz to 50 kHz, temperature interval 295-410 K, and irradiation dose Φ from 0.2 × 1016 cm-2 to 7 × 1016 cm-2. The noise amplitude was found monotonically increasing with the irradiation dose. With the irradiation dose increase, the noise spectra on the linear part of the current voltage characteristic transform from the 1/f noise to the generation recombination noise of at least two trap levels. One of these levels can be classified as Z1/2 with the capture cross section determined from the noise measurements to be ˜10-15 cm2.

  9. Large Aperture "Photon Bucket" Optical Receiver Performance in High Background Environments

    Science.gov (United States)

    Vilnrotter, Victor A.; Hoppe, D.

    2011-01-01

    The potential development of large aperture groundbased "photon bucket" optical receivers for deep space communications, with acceptable performance even when pointing close to the sun, is receiving considerable attention. Sunlight scattered by the atmosphere becomes significant at micron wavelengths when pointing to a few degrees from the sun, even with the narrowest bandwidth optical filters. In addition, high quality optical apertures in the 10-30 meter range are costly and difficult to build with accurate surfaces to ensure narrow fields-of-view (FOV). One approach currently under consideration is to polish the aluminum reflector panels of large 34-meter microwave antennas to high reflectance, and accept the relatively large FOV generated by state-of-the-art polished aluminum panels with rms surface accuracies on the order of a few microns, corresponding to several-hundred micro-radian FOV, hence generating centimeter-diameter focused spots at the Cassegrain focus of 34-meter antennas. Assuming pulse-position modulation (PPM) and Poisson-distributed photon-counting detection, a "polished panel" photon-bucket receiver with large FOV will collect hundreds of background photons per PPM slot, along with comparable signal photons due to its large aperture. It is demonstrated that communications performance in terms of PPM symbol-error probability in high-background high-signal environments depends more strongly on signal than on background photons, implying that large increases in background energy can be compensated by a disproportionally small increase in signal energy. This surprising result suggests that large optical apertures with relatively poor surface quality may nevertheless provide acceptable performance for deep-space optical communications, potentially enabling the construction of cost-effective hybrid RF/optical receivers in the future.

  10. Highly Efficient Noise-Assisted Energy Transport in Classical Oscillator Systems

    Science.gov (United States)

    León-Montiel, R. de J.; Torres, Juan P.

    2013-05-01

    Photosynthesis is a biological process that involves the highly efficient transport of energy captured from the Sun to a reaction center, where conversion into useful biochemical energy takes place. Using a quantum description, Rebentrost et al. [New J. Phys. 11, 033003 (2009)] and Plenio and Huelga [New J. Phys. 10, 113019 (2008)] have explained this high efficiency as the result of the interplay between the quantum coherent evolution of the photosynthetic system and noise introduced by its surrounding environment. Even though one can always use a quantum perspective to describe any physical process, since everything follows the laws of quantum mechanics, is the use of quantum theory imperative to explain this high efficiency? Recently, it has been shown by Eisfeld and Briggs [Phys. Rev. E 85, 046118 (2012)] that a purely classical model can be used to explain main aspects of the energy transfer in photosynthetic systems. Using this approach, we demonstrate explicitly here that highly efficient noise-assisted energy transport can be found as well in purely classical systems. The wider scope of applicability of the enhancement of energy transfer assisted by noise might open new ways for developing new technologies aimed at enhancing the efficiency of a myriad of energy transfer systems, from information channels in microelectronic circuits to long-distance high-voltage electrical lines.

  11. The high speed low noise multi-data processing signal process circuit research of remote sensing

    Science.gov (United States)

    Su, Lei; Jiang, Haibin; Dong, Wang

    2013-08-01

    The high speed, low noise and integration characteristic are the main technology and the main development directions on the signal process circuit of the image sensor, especially in high resolution remote sensing. With these developments, the high noise limiting circuits, high speed data transfer system and the integrated design of the signal process circuit become more and more important. Therefore the requirement of the circuit system simulation is more and more important during the system design and PCB board design process. A CCD signal process circuit system which has the high speed, low noise and several selectable operate modes function was designed and certificated in this paper, during the CCD signal process circuit system design, simulation was made which include the signal integrity and the power integrity. The important devices such as FPGA and the DDR2 device were simulated, using the power integrity simulation the sensitive power planes of the FPGA on the PCB was modified to make the circuit operate more stabilize on a higher frequency. The main clock path and the high speed data path of the PCB board were simulated with the signal integrity. All the simulation works make the signal process circuit system's image's SNR value get higher and make the circuit system could operate well on higher frequency. In the board testing process, the PCB time diagrams were listed on the testing chapter and the wave's parameter meets the request. The real time diagram and the simulated result of the PCB board was listed respectively. The CCD signal process circuit system's images' SNR (Signal Noise Ratio) value, the 14bit AFE slew rate and the data transfer frequency is listed in the paper respective.

  12. Development of a high-fidelity noise prediction and propagation model for noise generated from wind turbines

    DEFF Research Database (Denmark)

    Debertshäuser, Harald; Shen, Wen Zhong; Zhu, Wei Jun

    2015-01-01

    technique for any kind of flow conditions. We investigated laminar/ turbulent inflow, as well as wind shear and yaw of the 2.3 MW NM80 wind turbine. The turbulent case shows higher noise levels than the laminar one. Yaw changes the directivity from a dipole characteristic to an oval shape, inclined...

  13. Low Complexity DFT-Domain Noise PSD Tracking Using High-Resolution Periodograms

    NARCIS (Netherlands)

    Heusdens, R.; Hendriks, R.C.; Jensen, J.; Kjems, U.

    2009-01-01

    Although most noise reduction algorithms are critically dependent on the noise power spectral density (PSD), most procedures for noise PSD estimation fail to obtain good estimates in nonstationary noise conditions. Recently, a DFT-subspace-based method was proposed which improves noise PSD estimatio

  14. Low Complexity DFT-Domain Noise PSD Tracking Using High-Resolution Periodograms

    NARCIS (Netherlands)

    Heusdens, R.; Hendriks, R.C.; Jensen, J.; Kjems, U.

    2009-01-01

    Although most noise reduction algorithms are critically dependent on the noise power spectral density (PSD), most procedures for noise PSD estimation fail to obtain good estimates in nonstationary noise conditions. Recently, a DFT-subspace-based method was proposed which improves noise PSD

  15. Noise caused by semiconductor lasers in high-speed fiber-optic links

    DEFF Research Database (Denmark)

    Olsen, C. M.; Stubkjær, Kristian; Olesen, H.

    1989-01-01

    Theoretical and experimental results are presented for the signal-to-noise (S/N) ratio caused by mode partition noise, intensity noise, and reflection-induced noise in optical data links. Under given conditions an additional noise source with a S /N ratio of 20 dB will cause a power penalty of 1 d...

  16. Modeling high signal-to-noise ratio in a novel silicon MEMS microphone with comb readout

    Science.gov (United States)

    Manz, Johannes; Dehe, Alfons; Schrag, Gabriele

    2017-05-01

    Strong competition within the consumer market urges the companies to constantly improve the quality of their devices. For silicon microphones excellent sound quality is the key feature in this respect which means that improving the signal-to-noise ratio (SNR), being strongly correlated with the sound quality is a major task to fulfill the growing demands of the market. MEMS microphones with conventional capacitive readout suffer from noise caused by viscous damping losses arising from perforations in the backplate [1]. Therefore, we conceived a novel microphone design based on capacitive read-out via comb structures, which is supposed to show a reduction in fluidic damping compared to conventional MEMS microphones. In order to evaluate the potential of the proposed design, we developed a fully energy-coupled, modular system-level model taking into account the mechanical motion, the slide film damping between the comb fingers, the acoustic impact of the package and the capacitive read-out. All submodels are physically based scaling with all relevant design parameters. We carried out noise analyses and due to the modular and physics-based character of the model, were able to discriminate the noise contributions of different parts of the microphone. This enables us to identify design variants of this concept which exhibit a SNR of up to 73 dB (A). This is superior to conventional and at least comparable to high-performance variants of the current state-of-the art MEMS microphones [2].

  17. Dynamic Adaptive Median Filter (DAMF for Removal of High Density Impulse Noise

    Directory of Open Access Journals (Sweden)

    Punyaban Patel

    2012-10-01

    Full Text Available This paper proposes a novel adaptive filtering scheme to remove impulse noise from images. The scheme replaces the corrupted test pixel with the median value of non-corrupted neighboring pixels selected from a window dynamically. If the number of non-corrupted pixels in the selected window is not sufficient, a window of next higher size is chosen. Thus window size is automatically adapted based on the density of noise in the image as well as the density of corruption local to a window. As a result window size may vary pixel to pixel while filtering. The scheme is simple to implement and do not require multiple iterations. The efficacy of the proposed scheme is evaluated with respect to subjective as well as objective parameters on standard images on various noise densities. Comparative analysis reveals that the proposed scheme has improved performance over other schemes, preferably in high density impulse noise cases. Further, the computational overhead is also less as compared its competent scheme.

  18. High intensity interior aircraft noise increases the risk of high diastolic blood pressure in Indonesian Air Force pilots

    Directory of Open Access Journals (Sweden)

    Minarma Siagian

    2009-12-01

    Full Text Available Aim: To analyze the effects of aircraft noise, resting pulse rate, and other factors on the risk of high diastolic blood pressure (DBP in Indonesian Air Force pilots.Methods: A nested case-control study was conducted using data extracted from annual medical check-ups indoctrination aerophysiologic training records at the Saryanto Aviation and Aerospace Health Institute (LAKESPRA in Jakarta from January 2003 – September 2008. For analysis of DBP: the case group with DBP ≥ 90 mmHg were compared with contral group with DBP < 79 mmHG. One case matched to 12 controls.Results: Out of 567 pilots, 544 (95.9% had complete medical records. For this analysis there were 40 cases of high DBP and 480 controls for DBP. Pilots exposed to aircraft noise 90-95 dB rather than 70-80 dB had a 2.7-fold increase for high DBP [adjusted odds ratio (ORa = 2.70; 95% confi dence interval (CI = 1.05-6.97]. Pilots with resting pulse rates of ≥ 81/minute rather than ≤ 80/minute had a 2.7-fold increase for high DBP (ORa = 2.66; 95% CI = 1.26-5.61. In terms of total fl ight hours, pilots who had 1401-11125 hours rather than 147-1400 hours had a 3.2-fold increase for high DBP (ORa = 3.18; 95% CI = 1.01-10.03.Conclusion: High interior aircraft noise, high total flight hours,  and high resting pulse rate, increased risk for high DBP. Self assessment of resting pulse rate can be used to control the risk of high DBP. (Med J Indones 2009; 276: 276-82Keywords: diastolic blood pressure, aircraft noise, resting pulse rate, military pilots

  19. High-frequency Audiometry Hearing on Monitoring of Individuals Exposed to Occupational Noise: A Systematic Review.

    Science.gov (United States)

    Antonioli, Cleonice Aparecida Silva; Momensohn-Santos, Teresa Maria; Benaglia, Tatiana Aparecida Silva

    2016-07-01

    The literature reports on high-frequency audiometry as one of the exams used on hearing monitoring of individuals exposed to high sound pressure in their work environment, due to the method́s greater sensitivity in early identification of hearing loss caused by noise. The frequencies that compose the exam are generally between 9 KHz and 20KHz, depending on the equipment. This study aims to perform a retrospective and secondary systematic revision of publications on high-frequency audiometry on hearing monitoring of individuals exposed to occupational noise. This systematic revision followed the methodology proposed in the Cochrane Handbook, focusing on the question: "Is High-frequency Audiometry more sensitive than Conventional Audiometry in the screening of early hearing loss individuals exposed to occupational noise?" The search was based on PubMed data, Base, Web of Science (Capes), Biblioteca Virtual em Saúde (BVS), and in the references cited in identified and selected articles. The search resulted in 6059 articles in total. Of these, only six studies were compatible with the criteria proposed in this study. The performed meta-analysis does not definitively answer the study's proposed question. It indicates that the 16 KHz high frequency audiometry (HFA) frequency is sensitive in early identification of hearing loss in the control group (medium difference (MD = 8.33)), as well as the 4 KHz frequency (CA), this one being a little less expressive (MD = 5.72). Thus, others studies are necessary to confirm the HFA importance for the early screening of hearing loss on individuals exposed to noise at the workplace.

  20. On the Contribution of Active Galactic Nuclei to the High-Redshift Metagalactic Ionizing Background

    CERN Document Server

    D'Aloisio, Anson; McQuinn, Matthew; Trac, Hy; Shapiro, Paul R

    2016-01-01

    Motivated by the claimed detection of a large population of faint active galactic nuclei (AGN) at high redshift, recent studies have proposed models in which AGN contribute significantly to the z > 4 H I ionizing background. In some models, AGN are even the chief sources of reionization. If correct, these models would make necessary a complete revision to the standard view that galaxies dominated the high-redshift ionizing background. It has been suggested that AGN-dominated models can better account for two recent observations that appear to be in conflict with the standard view: (1) large opacity variations in the z ~ 5.5 H I Lyman-alpha forest, and (2) slow evolution in the mean opacity of the He II Lyman-alpha forest. Large spatial fluctuations in the ionizing background from the brightness and rarity of AGN may account for the former, while the earlier onset of He II reionization in these models may account for the latter. Here we show that models in which AGN emissions source >~ 50 % of the ionizing bac...

  1. High Background Ozone Events in the Houston-Galveston-Brazoria Area: Effects from Central American Fires

    Science.gov (United States)

    Lei, R.; Wang, S. C.; Yang, S.; Wang, Y.; Talbot, R. W.

    2016-12-01

    The policy-relevant background (PRB) ozone is defined by the U.S. Environmental Protection Agency (EPA) as the surface ozone mixing ratio that would occur over the U.S. without North American anthropogenic emission influences. PRB ozone over the Houston-Galveston-Brazoria (HGB) area may be affected by foreign sources due to its unique geographical location and meteorology. Our monitoring data revealed several high ozone events over HGB area which might be caused by Central American fire during the years of 2013-2015. To qualify the effects from Central American fire, we estimated the US, Central American and worldwide background over HGB area during those events using the GEOS-Chem global 3-D model. Anomalies in fire emissions leading to high PRB ozone were mapped through spatiotemporal sampling of the Fire INventory from NCAR (FINN) along background trajectories of air masses affecting the HGB area prior to and during the selected high PRB ozone days. Daily HGB PRB ozone estimated by researchers at the Texas Commission on Environmental Quality (TCEQ) was used as the data source to validate model results. Results showed that contribution of emission from Central American to HGB PRB ozone could be tripled during fire events compared to non-impacted fire days. Besides fire emissions from Central American, different types of meteorological events (e.g., cold fronts and thunderstorms) and high local photochemical production (e.g., heat waves and stagnation) are also found associated with high PRB ozone in HGB area during these events. Thus we imply that synthetic contribution from foreign sources and local meteorology to HGB PRB ozone warrants further investigated.

  2. High-fidelity Simulation of Jet Noise from Rectangular Nozzles . [Large Eddy Simulation (LES) Model for Noise Reduction in Advanced Jet Engines and Automobiles

    Science.gov (United States)

    Sinha, Neeraj

    2014-01-01

    This Phase II project validated a state-of-the-art LES model, coupled with a Ffowcs Williams-Hawkings (FW-H) far-field acoustic solver, to support the development of advanced engine concepts. These concepts include innovative flow control strategies to attenuate jet noise emissions. The end-to-end LES/ FW-H noise prediction model was demonstrated and validated by applying it to rectangular nozzle designs with a high aspect ratio. The model also was validated against acoustic and flow-field data from a realistic jet-pylon experiment, thereby significantly advancing the state of the art for LES.

  3. A low noise, high thermal stability, 0.1 K test facility for the Planck HFI bolometers

    Science.gov (United States)

    Paine, C. G.; Bock, J. J.; Hristov, V. V.; Lange, A. E.

    2002-05-01

    We are developing a facility which will be used to characterize the bolometric detectors for Planck, an ESA mission to investigate the Cosmic Microwave Background. The bolometers operate at 0.1 K, employing neutron-transmutation doped (NTD) Ge thermistors with resistances of several megohms to achieve NEPs˜1×10-17 W Hz-1/2. Characterization of the intrinsic noise of the bolometers at frequencies as low as 0.010 Hz dictates a test apparatus thermal stability of 40 nK Hz-1/2 to that frequency. This temperature stability is achieved via a multi-stage isolation and control geometry with high resolution thermometry implemented with NTD Ge thermistors, JFET source followers, and dedicated lock-in amplifiers. The test facility accommodates 24 channels of differential signal readout, for measurement of bolometer V(I) characteristics and intrinsic noise. The test facility also provides for modulated radiation in the submillimeter band incident on the bolometers, for measurement of the optical speed-of-response; this illumination can be reduced below detectable limits without interrupting cryogenic operation. A commercial Oxford Instruments dilution refrigerator provides the cryogenic environment for the test facility.

  4. High-frequency noise in FDSOI MOSFETs: a Monte Carlo investigation

    Science.gov (United States)

    Rengel, Raul; Mateos, Javier; Pardo, Daniel; Gonzalez, Tomas; Martin, Maria Jesus; Dambrine, Gilles; Danneville, Francois; Raskin, Jean-Pierre

    2003-05-01

    Due to the enormous industrial interest of the SOI MOSFET technology, a proper understanding of the physics underlying the behavior of these devices is necessary in order to optimize their high frequency performance. In this work, we study the static, dynamic and noise characteristics of FDSOI MOSFET"s by means of numerical simulations validated by comparison with experimental data. For this purpose, we use a 2D Ensemble Monte Carlo simulator, taking into account, in an appropriate manner, the physical topology of a fabricated 0.25 μm gate-length FDSOI transistor. Important effects appearing in real transistors, such as surface charges, contact resistances, impact ionization phenomena and extrinsic parasitics are included in the simulation. This allows to accurately reproduce the experimental behavior of static and dynamic parameters (output and transference characteristics, gm/ID ratio, capacitances, etc.). Moreover, results are explained by means of internal quantities such as concentration, velocity or energy of carriers. The results of the Monte Carlo simulations for the typical four noise parameters (NFmin, Gass, Rn, Gamma opt) of the 0.25 μm FDSOI MOSFET also show an exceptional agreement with experimental data. Once the reliability of the simulator has been confirmed, a full study of the noise characteristics of the device (noise sources, drain spectral densities, α, β and C parameters, etc.) is performed. Taking advantage of the possibilities of the Monte Carlo method as a pseudo-experimental approach, the influence on these noise characteristics of the variation of some geometry parameters (i.e., downscaling the gate length, thickness of the active layer or inclusion of HALO regions) is evaluated an interpreted in terms of microscopic transport processes.

  5. A method for improving the signal-to-noise ratio in IUE high-dispersion spectra

    Science.gov (United States)

    Welty, Daniel E.

    1988-01-01

    The flat-fielding technique was used to reduce fixed pattern noise in high dispersion IUE spectra, producing improvements in S/N of typically 40 percent compared with un-flat-fielded summed spectra. Weak spectral features may be more reliably identified. Such improvements are noted for specially obtained multiply-exposed images and for singly-exposed images taken from the IUE archives. However it is unclear if the technique is usable or as effective for all spectra.

  6. The Influence of High-Frequency Envelope Information on Low-Frequency Vowel Identification in Noise.

    Directory of Open Access Journals (Sweden)

    Wiebke Schubotz

    Full Text Available Vowel identification in noise using consonant-vowel-consonant (CVC logatomes was used to investigate a possible interplay of speech information from different frequency regions. It was hypothesized that the periodicity conveyed by the temporal envelope of a high frequency stimulus can enhance the use of the information carried by auditory channels in the low-frequency region that share the same periodicity. It was further hypothesized that this acts as a strobe-like mechanism and would increase the signal-to-noise ratio for the voiced parts of the CVCs. In a first experiment, different high-frequency cues were provided to test this hypothesis, whereas a second experiment examined more closely the role of amplitude modulations and intact phase information within the high-frequency region (4-8 kHz. CVCs were either natural or vocoded speech (both limited to a low-pass cutoff-frequency of 2.5 kHz and were presented in stationary 3-kHz low-pass filtered masking noise. The experimental results did not support the hypothesized use of periodicity information for aiding low-frequency perception.

  7. Air flow patterns and noise analysis inside high speed angular contact ball bearings

    Institute of Scientific and Technical Information of China (English)

    翟强; 闫柯; 张优云; 朱永生; 王亚泰

    2015-01-01

    The vortex formed around the rolling ball and the high pressure region formed around the ball−raceway contact zone are the principle factors that barricades the lubricant entering the bearing cavity, and further causes improper lubrication. The investigation of the air phase flow inside the bearing cavity is essential for the optimization of the oil−air two-phase lubrication method. With the revolutionary reference frame describing the bearing motion, a highly precise air phase flow model inside the angular contact ball bearing cavity was build up. Comprehensive factors such as bearing revolution, ball rotation, and cage structure were considered to investigate the influences on the air phase flow and heat transfer efficiency. The aerodynamic noise was also analyzed. The result shows that the ball spinning leads to the pressure rise and uneven pressure distribution. The air phase velocity, pressure and cage heat transfer efficiency increase as the revolving speed increases. The operating noise is largely due to the impact of the high speed external flow on the bearing. When the center of the oil−air outlet fixes near the inner ring, the aerodynamic noise is reduced. The position near the inner ring on the bigger axial side is the ideal position to fix the lubricating device for the angular contact ball bearing.

  8. Levels of thoron and progeny in high background radiation area of southeastern coast of Odisha, India.

    Science.gov (United States)

    Ramola, R C; Gusain, G S; Rautela, B S; Sagar, D V; Prasad, G; Shahoo, S K; Ishikawa, T; Omori, Y; Janik, M; Sorimachi, A; Tokonami, S

    2012-11-01

    Exposure to radon, (222)Rn, is assumed to be the most significant source of natural radiation to human beings in most cases. It is thought that radon and its progeny are major factors that cause cancer. The presence of thoron, (220)Rn, was often neglected because it was considered that the quantity of thoron in the environment is less than that of radon. However, recent studies have shown that a high thoron concentration was found in some regions and the exposure to (220)Rn and its progeny can equal or several time exceed that of (220)Rn and its progeny. The results of thoron and its progeny measurements in the houses of high background radiation area (HBRA) of the southeastern coast of Odisha, India presented here. This area is one of the high background radiation areas in India with a large deposit of monazite sand which is the probable source of thoron. Both active and passive methods were employed for the measurement of thoron and its progeny in cement, brick and mud houses in the study area. Thoron concentration was measured using RAD-7 and Raduet. A CR-39 track detector was employed for the measurement of environmental thoron progeny, both in active and passive modes. Thoron and its progeny concentrations were found to be comparatively high in the area. A comparison between the results obtained with various techniques is presented in this paper.

  9. The efficiency of reading around learned backgrounds

    Science.gov (United States)

    Eckstein, Miguel P.; Pham, Binh T.; Abbey, Craig K.; Zhang, Yani

    2006-03-01

    Most metrics of medical image quality typically treat all variability components of the background as a Gaussian noise process. This includes task based model observers (non-prewhitening matched filter without and with an eye filter, NPW and NPWE; Hotelling and Channelized Hotelling) as well as Fourier metrics of medical image quality based on the noise power spectra. However, many investigators have observed that unlike many of the models/metrics, physicians often can discount signal-looking structures that are part of the normal anatomic background. This process has been referred to as reading around the background or noise. The purpose of this paper is to develop an experimental framework to systematically study the ability of human observers to read around learned backgrounds and compare their ability to that of an optimal ideal observer which has knowledge of the background. We measured human localization performance of one of twelve targets in the presence of a fixed background consisting of randomly placed Gaussians with random contrasts and sizes, and white noise. Performance was compared to a condition in which the test images contained only white noise but with higher contrast. Human performance was compared to standard model observers that treat the background as a Gaussian noise process (NPW, NPWE and Hotelling), a Fourier-based prewhitening matched filter, and an ideal observer. The Hotelling, NPW, NPWE models as well as the Fourier-based prewhitening matched filter predicted higher performance for the white noise test images than the background plus white noise. In contrast, ideal and human performance was higher for the background plus white noise condition. Furthermore, human performance exceeded that of the NPW, NPWE and Hotelling models and reached an efficiency of 19% relative to the ideal observer. Our results demonstrate that for some types of images human signal localization performance is consistent with use of knowledge about the high order

  10. The analysis of reference background noise of f luxgate magnetometer GM4 at Hongshan Seismic Station%红山地震台磁通门磁力仪GM4参考背景噪声分析

    Institute of Scientific and Technical Information of China (English)

    王静; 胡秀娟; 罗娜; 李细顺; 王利兵; 宋昭; 畅国平

    2015-01-01

    This article analyzes preliminarily the data of reference background noise,which is chosen from GM4-1 fluxgate magnetometer instrument and GM4-2 fluxgate magnetometer instrument during the year of 2009 to 2013 at Hongshan Seismic Station. The result shows that the reference background noise of two instruments annual variation trend is consistent,and magnetic declination component changes with the seasons obviously,horizontal component and vertical component is not obvious. In addition,the background noise GM4-2 fluxgate magnetometer′s each component is more than that of GM4-1 fluxgate magnetometer instrument,which is caused by itself through the analysis by comparison.%选取红山地震台2009—2013年磁通门磁力仪 GM4-1和 GM4-2的参考背景噪声数据进行分析。结果显示:两套仪器背景噪声年变化趋势一致,其中 D 分量背景噪声随季节变化明显,H 分量、Z 分量不明显。另外,GM4-2仪各分量背景噪声值较高,认为是其自身原因引起的。

  11. Noise control of a flow around a cylinder using high-frequency dielectric barrier discharge plasma actuators

    Science.gov (United States)

    Kopiev, V. F.; Belyaev, I. V.; Zaytsev, M. Yu.; Kazansky, P. N.; Kopiev, V. A.; Moralev, I. A.

    2015-03-01

    The effect of high-frequency dielectric barrier discharge plasma actuators on the noise of a flow around a circular cylinder is experimentally studied. It is shown that the plasma actuators are able to reduce the vortex noise of a cylinder within the range of velocities typical for aeroacoustic applications.

  12. Eating disorder and depressive symptoms in urban high school girls from different ethnic backgrounds.

    Science.gov (United States)

    Bisaga, Katarzyna; Whitaker, Agnes; Davies, Mark; Chuang, Shirley; Feldman, Judith; Walsh, B Timothy

    2005-08-01

    This study examined ethnic group differences in the rates of eating disorder symptoms (EDS) and depressive disorder symptoms (DDS) with respect to ethnic identity, relative body weight, and abnormal eating behaviors among adolescent girls. A district-wide sample of high school girls (N = 1445) from different ethnic backgrounds was surveyed. EDS were assessed with the Eating Attitudes Test-26, abnormal eating behaviors with the Eating Behaviors Survey, and DDS with the Short Mood and Feelings Questionnaire. Two dimensions of ethnic identity, ethnic identity achievement and other group orientation, were assessed with Multi-Group Ethnic Identity Measure. Hispanic and non-Hispanic white girls had the highest and African-American (AA) and Caribbean girls the lowest rates of EDS. Asian girls reported the highest and AA girls the lowest rates of DDS. Early dieting was associated with EDS and DDS in Caribbean, non-Hispanic white, and mixed background girls. Relative body weight was related to EDS in all ethnic groups except in non-Hispanic white and mixed background girls. The authors did not find an effect of ethnic identity achievement on psychopathology, but there was an effect of other group orientation on both EDS and DDS. Clinicians should inquire about EDS and DDS in girls of all ethnic groups. Prevention efforts to delay unsupervised dieting may protect adolescent girls from the development of EDS and DDS.

  13. A High Spectral Resolution Observation of the Soft X-ray Diffuse Background with Thermal Detectors

    CERN Document Server

    McCammon, D; Apodaca, E; Tiest, W B; Cui, W; Deiker, S W; Galeazzi, M; Juda, M; Lesser, A; Mihara, T; Morgenthaler, J P; Sanders, W T; Zhang, J; Figueroa-Feliciano, E; Kelley, R L; Moseley, S H; Mushotzky, R F; Porter, F S; Stahle, C K; Szymkowiak, A E

    2002-01-01

    A high spectral resolution observation of the diffuse X-ray background in the 60 - 1000 eV energy range has been made using an array of thirty-six 1 mm^2 micro-calorimeters flown on a sounding rocket. Detector energy resolution ranged from 5-12 eV FWHM, and a composite spectrum of ~ 1 steradian of the background centered at l = 90, b = +60 was obtained with a net resolution of ~ 9 eV. The target area includes bright 1/4 keV regions, but avoids Loop I and the North Polar Spur. Lines of C VI, O VII, and O VIII are clearly detected with intensities of 5.4 +/- 2.3, 4.8 +/- 0.8, and 1.6 +/- 0.4 photons cm^-2 s^-1 sr^-1, respectively. The oxygen lines alone account for a majority of the diffuse background observed in the ROSAT R4 band that is not due to resolved extragalactic discrete sources. We also have a positive detection of the Fe-M line complex near 70 eV at an intensity consistent with previous upper limits that indicate substantial gas phase depletion of iron. We include a detailed description of the instr...

  14. Study of the CMS RPC detector performance in high radiation background conditions

    CERN Document Server

    Miguel Colin, Osvaldo

    2017-01-01

    The RPC system at the CMS Detector is operating successfully from beginning of the data taking. The high instantaneous luminosity causes an extremely high flux of ionizing particles. The long period of operation (Run1 and Run2) in a huge radiation background conditions, gives the opportunity to study the operation capability of the RPCs and also to predict a data-driven extrapolation about the expecting particle rates at HL LHC (High Luminosity) scenario. The obtained results in terms of measured rate, currents and integrated charged will be presented in the poster. When it is possible they will be compared to the relevant results obtained from the dedicated study where a set of test chambers have been irradiated at GIF++ laboratory setup.

  15. Constraints on the Extragalactic Background Light from Very High Energy Gamma-Ray Observations of Blazars

    OpenAIRE

    Finke, Justin D.; Razzaque, Soebur

    2009-01-01

    The extragalactic background light (EBL) from the infrared to the ultraviolet is difficult to measure directly, but can be constrained with a variety of methods. EBL photons absorb gamma-rays from distant blazars, allowing one to use blazar spectra from atmospheric Cherenkov telescopes (ACTs) to put upper limits on the EBL by assuming a blazar source spectrum. Here we apply a simple technique, similar to the one developed by Schroedter (2005), to the most recent very-high energy (VHE) gamma-r...

  16. Annoyance and activity disturbance induced by high-speed railway and conventional railway noise: a contrastive case study.

    Science.gov (United States)

    Di, Guo-Qing; Lin, Qi-Li; Li, Zheng-Guang; Kang, Jian

    2014-03-07

    High-speed railway (HR, Electrified railway with service speed above 200 km/h.) noise and conventional railway (CR, Electrified railway with service speed under 200 km/h.) noise are different in both time and frequency domain. There is an urgent need to study the influence of HR noise and consequently, develop appropriate noise evaluation index and limits for the total railway noise including HR and CR noise. Based on binaural recording of HR and CR noises in a approximate semi-free field, noise annoyance and activity disturbance induced by maximal train pass-by events in China were investigated through laboratory subjective evaluation. 80 students within recruited 102 students, 40 males and 40 females, 23.9 ± 2.1 years old, were finally selected as the subjects. After receiving noise stimulus via headphone of a binaural audio playback system, subjects were asked to express the annoyance or activity disturbance due to railway noise at a 0-100 numerical scale. The results show that with the same annoyance rating (A) or activity disturbance rating (D), the A-weighted equivalent sound pressure level (LAeq) of CR noise is approximately 7 dB higher than that of HR noise. Linear regression analysis between some acoustical parameters and A (or D) suggests that the coefficient of determination (R2) is higher with the instantaneous fast A-weighted sound pressure level (LAFmax) than that with LAeq. A combined acoustical parameter, LHC = 1.74LAFmax + 0.008LAFmax(Lp-LAeq), where Lp is the sound pressure level, was derived consequently, which could better evaluate the total railway noise, including HR and CR noise. More importantly, with a given LHC, the noise annoyance of HR and CR noise is the same. Among various acoustical parameters including LHC and LAeq, A and D have the highest correlation with LHC. LHC has been proved to be an appropriate index to evaluate the total railway noise, including both HR and CR. However, it should be pointed out that this study provides

  17. Signal and noise of Diamond Pixel Detectors at High Radiation Fluences

    CERN Document Server

    Tsung, Jieh-Wen; Hügging, Fabian; Kagan, Harris; Krüger, Hans; Wermes, Norbert

    2012-01-01

    CVD diamond is an attractive material option for LHC vertex detectors because of its strong radiation-hardness causal to its large band gap and strong lattice. In particular, pixel detectors operating close to the interaction point profit from tiny leakage currents and small pixel capacitances of diamond resulting in low noise figures when compared to silicon. On the other hand, the charge signal from traversing high energy particles is smaller in diamond than in silicon by a factor of about 2.2. Therefore, a quantitative determination of the signal-to-noise ratio (S/N) of diamond in comparison with silicon at fluences in excess of 10$^{15}$ n$_{eq}$ cm$^{-2}$, which are expected for the LHC upgrade, is important. Based on measurements of irradiated diamond sensors and the FE-I4 pixel readout chip design, we determine the signal and the noise of diamond pixel detectors irradiated with high particle fluences. To characterize the effect of the radiation damage on the materials and the signal decrease, the chang...

  18. Quantum limited noise figure operation of high gain erbium doped fiber amplifiers

    DEFF Research Database (Denmark)

    Lumholt, Ole; Povlsen, Jørn Hedegaard; Schüsler, Kim;

    1993-01-01

    powers below -5 dBm, and an improvement of 2.0 dB with a simultaneous gain increase of 4.1 dB is measured relative to a gain-optimized fiber. The optimum isolator location is evaluated for different pump and signal wavelengths in both an Al/Er-doped and a Ge/Er-doped fiber, for pump and signal power......Performance improvements obtained by using an isolator as an amplified-spontaneous-emission-suppressing component within erbium-doped fibers are evaluated. Simultaneous high-gain and near-quantum-limited noise figures can be obtained by such a scheme. The noise figure improves for input signal...... variations and different pump configurations. In all cases the optimum isolator position lies within 10-37% of the total fiber length for small signal operation...

  19. Longitudinal type-line optimization of high-speed train for low aerodynamic noise

    Institute of Scientific and Technical Information of China (English)

    肖友刚; 杨群; 孙亮; 时彧

    2014-01-01

    The basic head shape of high-speed train is determined by its longitudinal type-line (LTL), so it is crucial to optimize its aerodynamic performance. Based on the parametric modeling of LTL constructed by non-uniform relational B-spline (NURBS) and the fluctuation pressure obtained by large eddy simulation (LES), the Kriging surrogate model (KSM) of LTL was constructed for low aerodynamic noise, and the accuracy of the KSM was improved gradually by adding the sample point with maximum expected improvement (EI) and the optimal point from optimization. The optimal objective was searched with genetic algorithm (GA). The results show that the total fluctuation pressure level (FPL) of the optimal LTL can be 8.7 dB less than that of original one, and the shape optimization method is feasible for low aerodynamic noise design.

  20. Effects of Noise and Absorption on High Frequency Measurements of Acoustic-Backscatter from Fish

    Directory of Open Access Journals (Sweden)

    Masahiko Furusawa

    2015-01-01

    Full Text Available Quantitative echosounders operating at multiple frequencies (e.g., 18, 38, 70, 120, 200, 333, and 710 kHz are often used to observe fish and zooplankton and identify their species. At frequencies above 100 kHz, the absorption attenuation increases rapidly and decreases the signal-to-noise ratio (SNR. Also, incomplete compensation for the attenuation may result in measurement error. This paper addresses the effects of the attenuation and noise on high frequency measurements of acoustic backscatter from fish. It is shown that measurements of a fish with target strength of −40 dB at 200 m depth are limited by SNR to frequencies up to about 100 kHz. Above 100 kHz, absorption coefficients must be matched to local environmental conditions.

  1. Depict noise-driven nonlinear dynamic networks from output data by using high-order correlations

    CERN Document Server

    Chen, Yang; Chen, Tianyu; Wang, Shihong; Hu, Gang

    2016-01-01

    Many practical systems can be described by dynamic networks, for which modern technique can measure their output signals, and accumulate extremely rich data. Nevertheless, the network structures producing these data are often deeply hidden in these data. Depicting network structures by analysing the available data turns to be significant inverse problems. On one hand, dynamics are often driven by various unknown facts, called noises. On the other hand, network structures of practical systems are commonly nonlinear, and different nonlinearities can provide rich dynamic features and meaningful functions of realistic networks. So far, no method, both theoretically or numerically, has been found to systematically treat the both difficulties together. Here we propose to use high-order correlation computations (HOCC) to treat nonlinear dynamics; use two-time correlations to treat noise effects; and use suitable basis and correlator vectors to unifiedly depict all dynamic nonlinearities and topological interaction l...

  2. A High Input Impedance Low Noise Integrated Front-End Amplifier for Neural Monitoring.

    Science.gov (United States)

    Zhou, Zhijun; Warr, Paul A

    2016-12-01

    Within neural monitoring systems, the front-end amplifier forms the critical element for signal detection and pre-processing, which determines not only the fidelity of the biosignal, but also impacts power consumption and detector size. In this paper, a novel combined feedback loop-controlled approach is proposed to compensate for input leakage currents generated by low noise amplifiers when in integrated circuit form alongside signal leakage into the input bias network. This loop topology ensures the Front-End Amplifier (FEA) maintains a high input impedance across all manufacturing and operational variations. Measured results from a prototype manufactured on the AMS 0.35 [Formula: see text] CMOS technology is provided. This FEA consumes 3.1 [Formula: see text] in 0.042 [Formula: see text], achieves input impedance of 42 [Formula: see text], and 18.2 [Formula: see text] input-referred noise.

  3. Noise Pollution and Health Effects

    Directory of Open Access Journals (Sweden)

    Geravandi

    2015-01-01

    Full Text Available Background Noise pollution is of particular importance due to the physical and psychological effects on humans. Noise is a stressor that affects the autonomic nervous system and the endocrine system. Noise is also a threat to marine and terrestrial ecosystems. Health risks from noise are correlated with road traffic. In other words, noise health effects are the health consequences of elevated sound levels. Objectives This study aims to determine the effect of noise pollution (near roadways on health issues in Ahvaz, Iran. Materials and Methods In this cross-sectional study, equivalent sound pressure level were measured by sound level meters TES-1353 in 75 locations around 4 roadways, which had a high load of traffic in Ahvaz City during day time. During the study, 820 measurements were recorded at measuring stations, for 7 days per week with 1-hour interval between each measurement. Statistical analysis was carried out by SPSS software. Results According to the research findings, the equivalent sound pressure levels in all stations were 76.28 ± 3.12 dB (Mean ± SD. According to sound measurements and the survey questionnaire, noise pollution is higher than EPA (US Environmental Protection Agency and Iran standard level. Based on result of this study the worst noise health effects were the nervousness and sleep quality during 2012. Conclusions According to the results of this study, with increasing load of traffic, there is an increasing need for proper consideration plans to control noise pollution and prevent its effects.

  4. Variations in voice level and fundamental frequency with changing background noise level and talker-to-listener distance while wearing hearing protectors: A pilot study

    DEFF Research Database (Denmark)

    Bouserhal, Rachel E.; MacDonald, Ewen; Falk, Tiago H.;

    2016-01-01

    concern for people wearing hearing protection devices (HPD). Although practical, radio communication is cumbersome, as it does not distinguish designated receivers. A smarter radio communication protocol must be developed to alleviate this problem. Thus, it is necessary to model speech production in noise...... while wearing HPDs. Such a model opens the door to radio communication systems that distinguish receivers and offer more efficient communication between persons wearing HPDs. Design: This paper presents the results of a pilot study aimed to investigate the effects of occluding the ear on changes...... in voice level and fundamental frequency in noise and with varying talker-to-listener distance. Study sample: Twelve participants with a mean age of 28 participated in this study. Results: Compared to existing data, results show a trend similar to the open ear condition with the exception of the occluded...

  5. Variations in voice level and fundamental frequency with changing background noise level and talker-to-listener distance while wearing hearing protectors: A pilot study.

    Science.gov (United States)

    Bouserhal, Rachel E; Macdonald, Ewen N; Falk, Tiago H; Voix, Jérémie

    2016-01-01

    Speech production in noise with varying talker-to-listener distance has been well studied for the open ear condition. However, occluding the ear canal can affect the auditory feedback and cause deviations from the models presented for the open-ear condition. Communication is a main concern for people wearing hearing protection devices (HPD). Although practical, radio communication is cumbersome, as it does not distinguish designated receivers. A smarter radio communication protocol must be developed to alleviate this problem. Thus, it is necessary to model speech production in noise while wearing HPDs. Such a model opens the door to radio communication systems that distinguish receivers and offer more efficient communication between persons wearing HPDs. This paper presents the results of a pilot study aimed to investigate the effects of occluding the ear on changes in voice level and fundamental frequency in noise and with varying talker-to-listener distance. Twelve participants with a mean age of 28 participated in this study. Compared to existing data, results show a trend similar to the open ear condition with the exception of the occluded quiet condition. This implies that a model can be developed to better understand speech production for the occluded ear.

  6. Low-noise multichannel ASIC for high count rate X-ray diffractometry applications

    Energy Technology Data Exchange (ETDEWEB)

    Szczygiel, R. [AGH University of Science and Technology, Department of Measurement and Instrumentation, al. Mickiewicza 30, Krakow (Poland)], E-mail: robert.szczygiel@agh.edu.pl; Grybos, P.; Maj, P. [AGH University of Science and Technology, Department of Measurement and Instrumentation, al. Mickiewicza 30, Krakow (Poland); Tsukiyama, A.; Matsushita, K.; Taguchi, T. [Rigaku Corporation, 3-9-12 Matsubara-cho, Akishima-shi, Tokyo (Japan)

    2009-08-01

    RG64 is a 64-channel ASIC designed for the silicon strip detector readout and optimized for high count rate X-ray imaging applications. In this paper we report on the test results referring to the RG64 noise level, channel uniformity and the operation with a high rate of input signals. The parameters of the RG64-based diffractometry system are compared with the ones based on the scintillation counter. Diffractometry measurement results with silicon strip detectors of different strip lengths and strip pitch are also presented.

  7. Evaluation of High Level Environmental Background Radiation Areas and its Variation in Ramsar

    Directory of Open Access Journals (Sweden)

    Tayyeb Allahverdi Pourfallah

    2012-03-01

    Full Text Available Introduction The exposure of human beings to ionizing radiation from natural sources is a continuing and inescapable feature of life on earth. For most individuals, this exposure exceeds that from all man-made sources combined. Materials and Methods In this study, the annual effective dose in high level environmental background radiation areas (HLEBRAs of northern city of Ramsar in Iran was determined. For dosimetry, a gamma radiation dosimeter was used. Measurements were performed in more than 90 points in five districts with HLEBR around and near hot springs. Results In some areas, the annual effective dose from outdoor external gamma radiation in HLEBRAs (30 mSv/y exceeded the annual effective dose limit for radiation workers. Our results are evident that the population dose from normal background radiation in HLEBRAs is 200 times higher than corresponding values in Ramsar sea shore. To estimate the cosmic ray contribution, dose measurements were performed on the sea surface one km off the sea shore. Conclusion The observed differences over locations and measured doses between this study and the others revealed the dynamic nature of this phenomenon, and necessitate performing the periodic studies in these areas. Moreover, cytogenetic and immunologic researches for studying the long term effects of these high level environmental radiations on the residents of these HLEBRAs are necessary.

  8. Conditioning the γ spectrometer for activity measurement at very high background

    Institute of Scientific and Technical Information of China (English)

    YAN Wei-Hua; ZHANG Li-Guo; ZHANG Zhao; XIAO Zhi-Gang

    2012-01-01

    The application of a high purity Germanium (HPGe) γ spectrometer in determining the fuel element burnup in a future reactor is studied.The HPGe detector is exposed by a 60Co source with varying irradiation rate from 10× 103 s-1 to 150× 103 s-1 to simulate the input counting rate in real reactor environment.A 137Cs and a 152Eu source are positioned at given distances to generate a certain event rate in the detector with the former being proposed as a labeling nuclide to measure the burnup of a fuel element.It is shown that both the energy resolution slightly increasing with the irradiation rate and the passthrough rate at high irradiation level match the requirement of the real application.The influence of the background is studied in the different parameter sets used in the specially developed procedure of background subtraction.It is demonstrated that with the typical input irradiation rate and 137Cs intensity relevant to a deep burnup situation,the precision of the 137Cs counting rate in the current experiment is consistently below 2.8%,indicating a promising feasibility of utilizing an HPGe detector in the burnup measurement in future bed-like reactors.

  9. Enhanced trigger for the NIFFTE fissionTPC in presence of high-rate alpha backgrounds

    Science.gov (United States)

    Bundgaard, Jeremy; Niffte Collaboration

    2015-10-01

    Nuclear physics and nuclear energy communities call for new, high precision measurements to improve existing fission models and design next generation reactors. The Neutron Induced Fission Fragment Tracking experiment (NIFFTE) has developed the fission Time Projection Chamber (fissionTPC) to measure neutron induced fission with unrivaled precision. The fissionTPC is annually deployed to the Weapons Neutron Research facility at Los Alamos Neutron Science Center where it operates with a neutron beam passing axially through the drift volume, irradiating heavy actinide targets to induce fission. The fissionTPC was developed at the Lawrence Livermore National Laboratory's TPC lab, where it measures spontaneous fission from radioactive sources to characterize detector response, improve performance, and evolve the design. To measure 244Cm, we've developed a fission trigger to reduce the data rate from alpha tracks while maintaining a high fission detection efficiency. In beam, alphas from 239Pu are a large background when detecting fission fragments; implementing the fission trigger will greatly reduce this background. The implementation of the cathode fission trigger in the fissionTPC will be presented along with a detailed study of its efficiency.

  10. Thunderstorms as probable reason of high background neutron fluxes on L<1.2

    Science.gov (United States)

    Bratolyubova-Tsulukidze, L.; Grachev, E.; Grigoryan, O.; Kunitsyn, V.; Kuzhevskiy, B.; Nechaev, O.; Usanova, M.

    In this paper we analyze the neutron emission observations made in the experiment onboard MIR orbital station (1991), ISS (2002) and Colibri-2002 satellite (2002) at the altitude of 400 km. The helium discharge detectors made it possible to detect neutrons with energies ranging from 0.25eV to 1.9MeV. The spatial distribution of high background neutron fluxes has a longitude dependence. These events have been observed at -200 ... 600 and 1350 ...1800 ...- 1350 longitudinal intervals. The most intensive fluxes near the geomagnetic equator were registered in the African region. They are not found to be associated with increases of proton fluxes (Ep >50MeV). As a statistical set, the events appear to coincide with the most active region of atmospheric weather. In this paper we assess the possibility that the occurrence of high background neutron fluxes in the African region is connected with lightning discharges. To observe neutron emission at the altitude of 400 km ~101 0 neutrons are required to be produced by lightning discharge. These theoretical predictions suggest cloud charge values of about 250-300 Coulomb.

  11. Anderson Localization in high temperature QCD: background configuration properties and Dirac eigenmodes

    CERN Document Server

    Cossu, Guido

    2016-01-01

    We investigate the properties of the background gauge field configurations that act as disorder for the Anderson localization mechanism in the Dirac spectrum of QCD at high temperatures. We compute the eigenmodes of the M\\"obius domain-wall fermion operator on configurations generated for the $SU(3)$ gauge theory with two flavors of fermions, in the temperature range $[0.9,1.9]T_c$. We identify the source of localization of the eigenmodes with gauge configurations that are self-dual and support negative fluctuations of the Polyakov loop $P_L$, in the high temperature sea of $P_L\\sim 1$. The dependence of these observations on the boundary conditions of the valence operator is studied. We also investigate the spatial overlap of the left-handed and right-handed projected eigenmodes in correlation with the localization and the corresponding eigenvalue. We discuss an interpretation of the results in terms of monopole-instanton structures.

  12. Classification of high-energy antiprotons on electrons background based on calorimeter data in PAMELA experiment

    Science.gov (United States)

    Dunaeva, O. A.; Alekseev, V. V.; Bogomolov, Yu V.; Lukyanov, A. D.; Malakhov, V. V.; Mayorov, A. G.; Rodenko, S. A.

    2017-01-01

    In modern experimental physics a heterogeneous coordinate-sensitive calorimeters are widely used due to their good characteristics and possibilities to obtain a three-dimensional information of particles interactions. Especially it is important at high-energies when electromagnetic or hadron showers are arise. We propose a quit efficient method to identify antiprotons (positrons) with energies more than 10 GeV on electron (proton) background by calorimeter of such kind. We construct the AdaBoost classifier and SVM to separate particles into two classes, different combinations of energy release along reconstructed particle trajectory were used as feature vector. We test a preliminary version of the method on a calorimeter of the PAMELA magnetic spectrometer. For high-energy particles we got a good quality of classification: it lost about 5 · 10‑2 of antiprotons, and less than 4 · 10‑4 of electrons were classified to antiproton class.

  13. Fast cavity-enhanced atom detection with low noise and high fidelity

    Science.gov (United States)

    Goldwin, J.; Trupke, M.; Kenner, J.; Ratnapala, A.; Hinds, E.A.

    2011-01-01

    Cavity quantum electrodynamics describes the fundamental interactions between light and matter, and how they can be controlled by shaping the local environment. For example, optical microcavities allow high-efficiency detection and manipulation of single atoms. In this regime, fluctuations of atom number are on the order of the mean number, which can lead to signal fluctuations in excess of the noise on the incident probe field. Here we demonstrate, however, that nonlinearities and multi-atom statistics can together serve to suppress the effects of atomic fluctuations when making local density measurements on clouds of cold atoms. We measure atom densities below 1 per cavity mode volume near the photon shot-noise limit. This is in direct contrast to previous experiments where fluctuations in atom number contribute significantly to the noise. Atom detection is shown to be fast and efficient, reaching fidelities in excess of 97% after 10 μs and 99.9% after 30 μs. PMID:21829180

  14. Validation and application of an high-order spectral difference method for flow induced noise simulation

    KAUST Repository

    Parsani, Matteo

    2011-09-01

    The main goal of this paper is to develop an efficient numerical algorithm to compute the radiated far field noise provided by an unsteady flow field from bodies in arbitrary motion. The method computes a turbulent flow field in the near fields using a high-order spectral difference method coupled with large-eddy simulation approach. The unsteady equations are solved by advancing in time using a second-order backward difference formulae scheme. The nonlinear algebraic system arising from the time discretization is solved with the nonlinear lowerupper symmetric GaussSeidel algorithm. In the second step, the method calculates the far field sound pressure based on the acoustic source information provided by the first step simulation. The method is based on the Ffowcs WilliamsHawkings approach, which provides noise contributions for monopole, dipole and quadrupole acoustic sources. This paper will focus on the validation and assessment of this hybrid approach using different test cases. The test cases used are: a laminar flow over a two-dimensional (2D) open cavity at Re = 1.5 × 10 3 and M = 0.15 and a laminar flow past a 2D square cylinder at Re = 200 and M = 0.5. In order to show the application of the numerical method in industrial cases and to assess its capability for sound field simulation, a three-dimensional turbulent flow in a muffler at Re = 4.665 × 10 4 and M = 0.05 has been chosen as a third test case. The flow results show good agreement with numerical and experimental reference solutions. Comparison of the computed noise results with those of reference solutions also shows that the numerical approach predicts noise accurately. © 2011 IMACS.

  15. Noise suppression by noise

    OpenAIRE

    Vilar, J. M. G.; Rubí Capaceti, José Miguel

    2001-01-01

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

  16. High-Lift Propeller Noise Prediction for a Distributed Electric Propulsion Flight Demonstrator

    Science.gov (United States)

    Nark, Douglas M.; Buning, Pieter G.; Jones, William T.; Derlaga, Joseph M.

    2017-01-01

    Over the past several years, the use of electric propulsion technologies within aircraft design has received increased attention. The characteristics of electric propulsion systems open up new areas of the aircraft design space, such as the use of distributed electric propulsion (DEP). In this approach, electric motors are placed in many different locations to achieve increased efficiency through integration of the propulsion system with the airframe. Under a project called Scalable Convergent Electric Propulsion Technology Operations Research (SCEPTOR), NASA is designing a flight demonstrator aircraft that employs many "high-lift propellers" distributed upstream of the wing leading edge and two cruise propellers (one at each wingtip). As the high-lift propellers are operational at low flight speeds (take-off/approach flight conditions), the impact of the DEP configuration on the aircraft noise signature is also an important design consideration. This paper describes efforts toward the development of a mulit-fidelity aerodynamic and acoustic methodology for DEP high-lift propeller aeroacoustic modeling. Specifically, the PAS, OVERFLOW 2, and FUN3D codes are used to predict the aerodynamic performance of a baseline high-lift propeller blade set. Blade surface pressure results from the aerodynamic predictions are then used with PSU-WOPWOP and the F1A module of the NASA second generation Aircraft NOise Prediction Program to predict the isolated high-lift propeller noise source. Comparisons of predictions indicate that general trends related to angle of attack effects at the blade passage frequency are captured well with the various codes. Results for higher harmonics of the blade passage frequency appear consistent for the CFD based methods. Conversely, evidence of the need for a study of the effects of increased azimuthal grid resolution on the PAS based results is indicated and will be pursued in future work. Overall, the results indicate that the computational

  17. Noise Affects Performance on the Montreal Cognitive Assessment.

    Science.gov (United States)

    Dupuis, Kate; Marchuk, Veronica; Pichora-Fuller, M Kathleen

    2016-09-01

    We investigated the effect of background noise on performance on the Montreal Cognitive Assessment (MoCA). Two groups of older adults (one with clinically normal hearing, one with hearing loss) and a younger adult group with clinically normal hearing were administered two versions of the MoCA under headphones in low and high levels of background noise. Intensity levels used to present the test were customized based on the hearing abilities of participants with hearing loss to yield a uniform level of difficulty across listeners in the high-level noise condition. Both older groups had poorer MoCA scores in noise than the younger group. Importantly, all participants had poorer MoCA scores in the high-noise (M = 22.7/30) compared to the low-noise condition (M = 25.7/30, p noise in the test environment should be considered when cognitive tests are conducted and results interpreted, especially when testing older adults.

  18. Ppb-level H2S detection for SF6 decomposition based on a fiber-amplified telecommunication diode laser and a background-gas-induced high-Q photoacoustic cell

    Science.gov (United States)

    Yin, Xukun; Dong, Lei; Wu, Hongpeng; Ma, Weiguang; Zhang, Lei; Yin, Wangbao; Xiao, Liantuan; Jia, Suotang; Tittel, Frank K.

    2017-07-01

    A ppb-level hydrogen sulfide (H2S) gas sensor for sulfur hexafluoride (SF6) decomposition analysis was developed by means of a background-gas-induced high-Q differential photoacoustic cell (PAC) and a fiber-amplified telecommunication diode laser. The watt-level excitation laser power compensates the sensitivity loss as a result of using a low cost, near-IR laser source. The differential design with a large cylindrical resonator diameter allows the PAC to accommodate the high power beam and maintain a low noise level output. The theory of background-gas-induced high-Q PAC is provided and was verified experimentally. A H2S detection limit (1σ) of 109 ppb in a SF6 buffer gas was achieved for an averaging time of 1 s, which corresponds to a normalized noise equivalent absorption coefficient of 2.9 × 10-9 cm-1 W Hz-1/2.

  19. Ingestion of polonium ((210)Po) via dietary sources in high background radiation areas of south India.

    Science.gov (United States)

    Arunachalam, Kantha Deivi; Baskaran, Kamesh Viswanathan; Rao, D D; Sathyapriya, R; Annamalai, Sathesh Kumar; Kuruva, Jaya Krishna; Hari, Shanmugamsundaram

    2014-10-01

    To study the distribution of Polonium ((210)Po) activity in dietary sources in the high background radiation zone of Puttetti in southern Tamil Nadu. (210)Po was analyzed in the food materials consumed by the male and female individual representatives living in the high background areas by 24-h Duplicate Diet Study (DDS) and Market Basket Study (MBS). The MBS was performed by collecting the food samples such as, cereals, fruits, leafy vegetables, roots and tubers, other vegetables, fish, meat and milk grown in the high background radiation zone of southern Tamil Nadu as a part of baseline study in this region. The DDS was done by collecting the food materials consumed including the beverages in 24 h from different age groups of male and female individuals living in the village of Puttetti. The intake and ingestion dose of the radionuclide (210)Po was estimated. The average concentration of (210)Po in DDS (n = 33) was found to be 74 mBq.kg(- 1) of fresh weight. The MBS was collected based on food consumption representing more than 85-95% of annual supply, and were divided into eight food groups. The average concentration of (210)Po in the eight food groups namely leafy vegetables was 2176 mBq.kg(- 1) (n = 3), vegetables 55 mBq.kg(- 1) (n = 10), roots and tubers 251 mBq.kg(- 1) (n = 4), fruits 65 mBq.kg(- 1) (n = 5), fish 345 mBq.kg(- 1) (n = 2), meat food 117 mBq.kg(- 1) (n = 3), milk 20 mBq.kg(- 1) (n = 1) and cereal 290 (n = 1) mBq.kg(- 1) of fresh weight, respectively. The annual intake and ingestion dose due to (210)Po was estimated by DDS and MBS in adults, adolescents and children. The overall results showed that the MBS was moderately higher than the DDS in all age groups. Moreover, a DDS approach may even be more realistic, as cooked foodstuffs are used for dietary exposure assessment. The study confirms that the current levels of (210)Po do not pose a significant radiological risk to the local inhabitants.

  20. Thermal Infrared Sky Background for a High-Arctic Mountain Observatory

    CERN Document Server

    Steinbring, Eric

    2016-01-01

    Nighttime zenith sky spectral brightness in the 3.3 to 20 micron wavelength region is reported for an observatory site nearby Eureka, on Ellesmere Island in the Canadian High Arctic. Measurements derive from an automated Fourier-transform spectrograph which operated continuously there over three consecutive winters. During that time the median through the most transparent portion of the Q window was 460 Jy/square-arcsec, falling below 32 Jy/square-arcsec in N band, and to sub-Jansky levels by M and shortwards; reaching only 36 mJy/square-arcsec within L. Nearly six decades of twice-daily balloonsonde launches from Eureka, together with contemporaneous meteorological data plus a simple model allows characterization of background stability and extrapolation into K band. This suggests the study location has dark skies across the whole thermal infrared spectrum, typically sub-200 micro-Jy/square-arcsec at 2.4 microns. That background is comparable to South Pole, and more than an order of magnitude less than estim...

  1. Thermal Infrared Sky Background for a High-Arctic Mountain Observatory

    Science.gov (United States)

    Steinbring, Eric

    2017-01-01

    Nighttime zenith sky spectral brightness in the 3.3-20 μm wavelength region is reported for an observatory site nearby Eureka on Ellesmere Island in the Canadian High Arctic. Measurements are derived from an automated Fourier-transform spectrograph that operated there continuously over three consecutive winters. During that time, the median through the most transparent portion of the Q window was 460 {Jy} {{arcsec}}-2, falling below 32 {Jy} {{arcsec}}-2 in the N band, and to sub-Jansky levels by M and shortward, reaching only 36 {mJy} {{arcsec}}-2 within L. Nearly six decades of twice-daily balloonsonde launches from Eureka, together with contemporaneous meteorological data plus a simple model, allows characterization of background stability and extrapolation into K band. This suggests that the study location has dark skies across the whole thermal infrared spectrum, typically sub-200 μ {Jy} {{arcsec}}-2 at 2.4 μm. That background is comparable to South Pole and more than an order of magnitude less than estimates for the best temperate astronomical sites, all at much higher elevation. Considerations relevant to future facilities, including for polar transient surveys, are discussed.

  2. Observation of the Fundamental Nyquist Noise Limit in an Ultra-High $Q$-Factor Cryogenic Bulk Acoustic Wave Cavity

    CERN Document Server

    Goryachev, Maxim; van Kann, Frank; Galliou, Serge; Tobar, Michael E

    2014-01-01

    Thermal Nyquist noise fluctuations of high-$Q$ Bulk Acoustic Wave (BAW) cavities have been observed at cryogenic temperatures with a DC Superconducting Quantum Interference Device (SQUID) amplifier. High $Q$ modes with bandwidths of few tens of milliHz produce thermal fluctuations with a Signal-To-Noise ratio of up to 23dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high ($Q>10^8$ at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.

  3. High Intensity Pressure Noise Transmission in Human Ear: A Three Dimensional Simulation Study

    Science.gov (United States)

    Hawa, Takumi; Gan, Rong; Leckness, Kegan

    2015-03-01

    High intensity pressure noise generated by explosions and jet engines causes auditory damage and hearing loss of the military service personals, which are the most common disabilities in the veterans. Authors have investigated the high intensity pressure noise transmission from the ear canal to middle ear cavity. A fluid-structure interaction with a viscoelastic model for the tympanic membrane (TM) as well as the ossicular chain has been considered in the study. For the high intensity pressure simulation the geometry of the ear was based on a 3D finite element (FE) model of the human ear reported by Gan et al. (Ann Biomed Eng 2004). The model consists of the ear canal, TM, ossicular chain, and the middle ear cavity. The numerical approach includes two steps: 1) FE based finite-volume method simulation to compute pressure distributions in the ear canal and the middle ear cavity using CFX; and 2) FE modeling of TM and middle ear ossicles in response to high intensity sound using multi-physics analysis in ANSYS. The simulations provide the displacement of the TM/ossicular chain and the pressure fields in the ear canal and the middle ear cavity. These results are compared with human temporal bone experimental data obtained in our group. This work was supported by DOD W81XWH-14-1-0228.

  4. 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.

  5. Characterization of a high-temperature superconducting bearing for use in a cosmic microwave background polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R [Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Hanany, Shaul [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Matsumura, Tomotake [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Johnson, Bradley [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Jones, Terry [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2005-02-01

    We have previously presented a design for a cosmic microwave background (CMB) polarimeter in which a cryogenically cooled half-wave plate rotates by means of a high-temperature superconducting (HTS) bearing. Here, a prototype bearing, consisting of a commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured its coefficient of friction and vibrational property as a function of several parameters, including temperature between 15 and 83 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm and ambient pressure of {approx}10{sup -7} Torr. We concluded that the low rotational drag of the HTS bearing would allow rotations for long periods with minimal input power and negligible wear and tear, thus making this technology suitable for a future satellite mission.

  6. Characterization of a high-temperature superconducting bearing for use in a cosmic microwave background polarimeter

    Science.gov (United States)

    Hull, John R.; Hanany, Shaul; Matsumura, Tomotake; Johnson, Bradley; Jones, Terry

    2005-02-01

    We have previously presented a design for a cosmic microwave background (CMB) polarimeter in which a cryogenically cooled half-wave plate rotates by means of a high-temperature superconducting (HTS) bearing. Here, a prototype bearing, consisting of a commercially available ring-shaped permanent magnet and an array of YBCO bulk HTS material, has been constructed. We measured its coefficient of friction and vibrational property as a function of several parameters, including temperature between 15 and 83 K, rotation frequency between 0.3 and 3.5 Hz, levitation distance between 6 and 10 mm and ambient pressure of {\\sim }10^{- 7} Torr. We concluded that the low rotational drag of the HTS bearing would allow rotations for long periods with minimal input power and negligible wear and tear, thus making this technology suitable for a future satellite mission.

  7. A low noise and high precision linear power supply with thermal foldback protection

    Science.gov (United States)

    Carniti, P.; Cassina, L.; Gotti, C.; Maino, M.; Pessina, G.

    2016-05-01

    A low noise and high precision linear power supply was designed for use in rare event search experiments with macrobolometers. The circuit accepts at the input a "noisy" dual supply voltage up to ±15 V and gives at the output precise, low noise, and stable voltages that can be set between ±3.75 V and ±12.5 V in eight 1.25 V steps. Particular care in circuit design, component selection, and proper filtering results in a noise spectral density of 50 nV / √{ Hz } at 1 Hz and 20 nV / √{ Hz } white when the output is set to ±5 V. This corresponds to 125 nV RMS (0.8 μV peak to peak) between 0.1 Hz and 10 Hz, and 240 nV RMS (1.6 μV peak to peak) between 0.1 Hz and 100 Hz. The power supply rejection ratio (PSRR) of the circuit is 100 dB at low frequency, and larger than 40 dB up to high frequency, thanks to a proper compensation design. Calibration allows to reach a precision in the absolute value of the output voltage of ±70 ppm, or ±350 μV at ±5 V, and to reduce thermal drifts below ±1 ppm/∘C in the expected operating range. The maximum peak output current is about 6 A from each output. An original foldback protection scheme was developed that dynamically limits the maximum output current to keep the temperature of the output transistors within their safe operating range. An add-on card based on an ARM Cortex-M3 microcontroller is devoted to the monitoring and control of all circuit functionalities and provides remote communication via CAN bus.

  8. Imaging the lithospheric structure of the High Lava Plains, Oregon with ambient noise tomography

    Science.gov (United States)

    Hanson-Hedgecock, S.; Wagner, L. S.; Fouch, M. J.

    2010-12-01

    We use ambient noise tomography (ANT) to image the 3-D structure of the crust and uppermost mantle beneath the High Lava Plains, Oregon using data from ~300 broadband stations of the High Lava Plains seismic experiment and the EarthScope/USArray Transportable Array (TA). The High Lava Plains consists of WNW progressive silicic volcanism, beginning ~14.5 Ma near the Owyhee Plateau and continuing to ~1.5 Ma in outpourings near the Newberry caldera. Superimposed basaltic volcanism has occurred along the hotspot since ~10.5 Ma. The Snake River Plain’s volcanism has been associated with a Yellowstone hot spot due to its alignment with North American plate motion, but the High Lava Plains volcanism does not have a comparably straightforward explanation. Recent results from a surface wave tomographic study of the Yellowstone/Snake River Plains (YSRP) reveal a discrete low velocity anomaly in the upper mantle that shallows to the northeast, consistent with plate motion over a stationary heat source. The same study shows a discontinuous low velocity anomaly beneath the High Lava Plains, indicating a less continuous east to west heat source along the HLP volcanic track. To better resolve the shallow velocity structure beneath the High Lava Plains, ANT is used to determine phase velocity maps at periods of <8s to 40s. At periods between 20 and 40s the ambient noise phase velocity maps complement the surface wave tomographic results and provide additional constraints on velocity structure. ANT has improved lateral resolution, compared to traditional surface wave tomography, because of the more homogenous azimuthal content of ambient noise. Vertical resolution of shallower crustal structures is also improved; ANT is able to resolve velocity structures at periods below 20s. Lastly, the dense station spacing of the combined HLP and TA dataset allows the shallow structure of the High Lava Plains to be imaged in more detail than previous ANT studies that focused on the entire

  9. Using Subspace Method to Improve the Speech Quality in a Colored Noise Background%用子空间提高有色噪声背景下的语音质量

    Institute of Scientific and Technical Information of China (English)

    武奕峰; 贾海蓉; 郭欣

    2015-01-01

    Aiming at the problem of the decline of speech quality resulted from the interfer‐ence of the surrounding colored noise environment ,an algorithm is proposed in this paper to im‐prove the speech quality as well as the auditory perception ,and to reduce the users’ auditory fa‐tigue .The algorithm obtains updated optimal eigenvalue estimation equations through the simul‐taneous diagonalization of noise eigenvalue by real‐time tracking using non‐stationary noise esti‐mation and signal eigenvalue .In addition ,the noisy speech is processed by wiener filter in order to further eliminate the colored noise .Experimental results show that ,in the background of different decibel colored noise ,the new algorithm has apparently improved the speech signal‐to‐noise ratio and reduced the musical residual noise compared with the traditional subspace algorithm .%针对在语音通信过程中,纯净语音信号经常受到周围有色噪声环境干扰导致语音质量下降的问题,提出了一种用子空间提高语音质量,改善听觉感知度,降低用户听觉疲劳感的算法。该算法通过用非平稳噪声估计方法实时跟踪噪声信号的特征值,对跟踪的噪声和信号进行对角化;为了进一步消除有色噪声,对带噪语音再次进行维纳滤波处理,最后获得更新的最优特征值估计方程。实验结果表明,在信噪比不同的工厂噪声等有色噪声背景下,与传统子空间的算法相比,经过新算法的语音信噪比得到了明显的提高,且有效地降低了音乐噪声。

  10. Application of High Order X-LMS Filter for Active Noise Control

    Directory of Open Access Journals (Sweden)

    N.V.K.Mahalakshmi

    2014-06-01

    Full Text Available In this paper active noise is controlled by using higher order X-LMS (least mean square filter. This technique is based on X-NLMS (normalized least mean square, also known as traditional acoustic noise cancellation (ANC scheme. It cancels the wideband noise from the corrupted speech signal. The active noise reducing headphone is probably the most successful application of active control of sound – the technology of cancelling sound with sound i.e., by using anti-noise signal. This report presents an outlined technical review of noise cancellation in headphones. The principles of passive noise attenuation are presented after which active attenuation is introduced showing how the two complement the attenuation performance. In real-time environment, the number of different applications in which adaptive techniques are being successfully used that are echo cancellation, equalization of dispersive channels, system identification, signal enhancement, noise cancelling and control.

  11. Fermi-LAT high-z active galactic nuclei and the extragalactic background light

    Science.gov (United States)

    Armstrong, Thomas; Brown, Anthony M.; Chadwick, Paula M.

    2017-10-01

    Observations of distant gamma-ray sources are hindered by the presence of the extragalactic background light (EBL). In order to understand the physical processes that result in the observed spectrum of sources, it is imperative that a good understanding of the EBL is included. In this work, an investigation into the imprint of the EBL on the observed spectra of high-redshift Fermi-LAT active galactic nuclei is presented. By fitting the spectrum below ˜10 GeV, an estimation of the unabsorbed intrinsic source spectrum is obtained; by applying this spectrum to data up to 300 GeV, it is then possible to derive a scaling factor for different EBL models. A second approach uses five sources (PKS 0426-380, 4C +55.17, Ton 116, PG 1246+586 and RBS 1432) that were found to exhibit very high energy (VHE) emission (Eγ > 100 GeV). Through Monte Carlo simulations, it is shown that the observation of VHE photons, despite the large distances of these objects, is consistent with current EBL models. Many of these sources would be observable with the upcoming ground-based observatory, the Cherenkov Telescope Array, leading to a better understanding of the EBL.

  12. A LOW NOISE, HIGH-SPEED COMPENSATED CMOS OP-AMP DESIGN TECHNIQUE

    Directory of Open Access Journals (Sweden)

    SOUMYA SHATAKSHI PANDA

    2013-01-01

    Full Text Available In this paper, we have proposed a new methodology for the design of low frequency, low noise and high speed compensated CMOS op-amp which specifies open loop circuit parameters to obtain enhanced gain, settling time and closed loop stability. The op-amp which we have designed consists of an Operational Transconductance Amplifier (OTA followed by an output buffer. The OTA design involves the use of a continuous-time Common mode feedback circuit which maintains the output common voltage at the required level while maximizing the output swing and the desired compensation is done with a capacitor connected between the input and output of the buffer. The low noise high speed Op-Amp is designed using 180nm CMOS technology and exhibits 88 dB DC gain. For a parallel combination of 2 pF and 1 kΩ load, the unity gain frequency and phase margin are found to be 251 MHz and 37o respectively. Under the same load condition, the proposed compensation method results in a roughly 1.8 times increase in unity gain frequency i.e 392 MHz and a 33o improvement in the phase marginas compared to the conventional approach.

  13. Improved energy resolution of highly segmented HPGe detectors by noise reduction

    Energy Technology Data Exchange (ETDEWEB)

    Wiens, A.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Hess, H.; Pascovici, Gh.; Reiter, P. [Institut fuer Kernpyhsik, Koeln (Germany); Bazzacco, D.; Farnea, E.; Michelagnoli, C.; Recchia, F. [INFN, Sezione di Padova, Padova (Italy); Collaboration: for the AGATA Collaboration

    2013-04-15

    Built-in redundancies in highly segmented high-purity Ge detectors are exploited to increase the energy resolution of these semiconductor devices for detection of electromagnetic radiation in the X-ray and {gamma}-ray regime. The information of the two electronically decoupled independent measurements, the cathode and the anode electrodes, provides an improved signal-to-noise ratio through a combination of the individually measured signals performed on an event-by-event basis. The average energy resolution values of the AGATA triple cluster detector for an energy deposition of 60keV was measured to be 1.1 keV (FWHM) for the 36 segments and 1.2 keV for the core. The averaged signals of the core and the segments show an improved resolution value of 0.87 keV which is close to the expected theoretical limit. At higher {gamma}-ray energy the averaging technique allows for an enhanced energy resolution with a FWHM of 2.15keV at 1.3MeV. By means of the position sensitive operation of AGATA a new value for the Fano factor was determined and the noise contributions to the FWHM of a {gamma}-ray peak separated. (orig.)

  14. Harmonic Retrieval Embedded in Hybrid Colored Noise: a Novel Pisarenko Method Based on Cross-high-order Cumulant

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Spectral estimation method is an effective method in the case of parameter estimation of sinusoid signal in noises.It always applies cross-spectral estimation theory and high-order self-spectral estimation methods up to now.Yule-Walker equation based on cross-fourth-order cumulant is developed and Pisarenko method is provided in this paper.Simulation results show that the method is effective to retrieve sinusoid signal frequencies from hybrid colored noises and has good performance.

  15. Development of a shock noise prediction code for high-speed helicopters - The subsonically moving shock

    Science.gov (United States)

    Tadghighi, H.; Holz, R.; Farassat, F.; Lee, Yung-Jang

    1991-01-01

    A previously defined airfoil subsonic shock-noise prediction formula whose result depends on a mapping of the time-dependent shock surface to a time-independent computational domain is presently coded and incorporated in the NASA-Langley rotor-noise prediction code, WOPWOP. The structure and algorithms used in the shock-noise prediction code are presented; special care has been taken to reduce computation time while maintaining accuracy. Numerical examples of shock-noise prediction are presented for hover and forward flight. It is confirmed that shock noise is an important component of the quadrupole source.

  16. Reducing Magnetic Noise of an Unmanned Aerial Vehicle for High-Quality Magnetic Surveys

    Directory of Open Access Journals (Sweden)

    Boris Sterligov

    2016-01-01

    Full Text Available The use of light and ultralight unmanned aerial vehicles (UAVs for magnetic data acquisition can be efficient for resolving multiple geological and engineering tasks including geological mapping, ore deposits’ prospecting, and pipelines’ monitoring. The accuracy of the aeromagnetic data acquired using UAV depends mainly on deviation noise of electric devices (engine, servos, etc.. The goal of this research is to develop a nonmagnetic unmanned aerial platform (NUAP for high-quality magnetic surveys. Considering parameters of regional and local magnetic survey, a fixed-wing UAV suits geological tasks better for plain area and copter type for hills and mountains. Analysis of the experimental magnetic anomalies produced by a serial light fixed-wing UAV and subsequent magnetic and aerodynamic modeling demonstrates a capacity of NUAP with internal combustion engine carrying an atomic magnetic sensor mounted on the UAV wings to facilitate a high-quality magnetic survey.

  17. Method to Produce Flexible Ceramic Thermal Protection System Resistant to High Aeroacoustic Noise

    Science.gov (United States)

    Sawko, Paul M. (Inventor); Calamito, Dominic P. (Inventor); Jong, Anthony (Inventor)

    1997-01-01

    A method of producing a three dimensional angle interlock ceramic fiber which is stable to high aeroacoustic noise of about 170 decibels and to high temperatures of about 2500 F is disclosed. The method uses multiple separate strands of a ceramic fiber or ceramic tow suitable for weaving having multiple warp fibers and multiple fill fibers woven with a modified fly-shuttle loom or rapier shuttleless loom which has nip rolls, a modified fabric advancement mechanism and at least eight harnesses in connection with a Dobby pattern chain utilizing sufficient heddles for each warp fiber and a reed which accommodates at least 168 ends per inch. The method produces a multilayered top fabric, rib fabric and single-layered bottom fabric.

  18. ACCURATE DETECTION OF HIGH-SPEED MULTI-TARGET VIDEO SEQUENCES MOTION REGIONS BASED ON RECONSTRUCTED BACKGROUND DIFFERENCE

    Institute of Scientific and Technical Information of China (English)

    Zhang Wentao; Li Xiaofeng; Li Zaiming

    2001-01-01

    The paper first discusses shortcomings of classical adjacent-frame difference. Sec ondly, based on the image energy and high order statistic(HOS) theory, background reconstruction constraints are setup. Under the help of block-processing technology, background is reconstructed quickly. Finally, background difference is used to detect motion regions instead of adjacent frame difference. The DSP based platform tests indicate the background can be recovered losslessly in about one second, and moving regions are not influenced by moving target speeds. The algorithm has important usage both in theory and applications.

  19. High-fidelity two-qubit gates via dynamical decoupling of local 1 /f noise at the optimal point

    Science.gov (United States)

    D'Arrigo, A.; Falci, G.; Paladino, E.

    2016-08-01

    We investigate the possibility of achieving high-fidelity universal two-qubit gates by supplementing optimal tuning of individual qubits with dynamical decoupling (DD) of local 1 /f noise. We consider simultaneous local pulse sequences applied during the gate operation and compare the efficiencies of periodic, Carr-Purcell, and Uhrig DD with hard π pulses along two directions (πz /y pulses). We present analytical perturbative results (Magnus expansion) in the quasistatic noise approximation combined with numerical simulations for realistic 1 /f noise spectra. The gate efficiency is studied as a function of the gate duration, of the number n of pulses, and of the high-frequency roll-off. We find that the gate error is nonmonotonic in n , decreasing as n-α in the asymptotic limit, α ≥2 , depending on the DD sequence. In this limit πz-Urhig is the most efficient scheme for quasistatic 1 /f noise, but it is highly sensitive to the soft UV cutoff. For small number of pulses, πz control yields anti-Zeno behavior, whereas πy pulses minimize the error for a finite n . For the current noise figures in superconducting qubits, two-qubit gate errors ˜10-6 , meeting the requirements for fault-tolerant quantum computation, can be achieved. The Carr-Purcell-Meiboom-Gill sequence is the most efficient procedure, stable for 1 /f noise with UV cutoff up to gigahertz.

  20. High-Redshift Star Formation in a Time-Dependent Lyman-Werner Background

    CERN Document Server

    Visbal, Eli; Terrazas, Bryan; Bryan, Greg L; Barkana, Rennan

    2014-01-01

    The first generation of stars produces a background of Lyman-Werner (LW) radiation which can photo-dissociate molecular hydrogen, increasing the mass of dark matter halos required to host star formation. Previous studies have determined the critical mass required for efficient molecular cooling with a constant LW background. However, the true background is expected to increase rapidly at early times. Neglecting this evolution could underestimate star formation in small halos that may have started to cool in the past when the LW intensity was much lower. Background evolution is a large source of uncertainty in pre-reionization predictions of the cosmological 21cm signal, which can be observed with future radio telescopes. To address this, we perform zero-dimentional one-zone calculations that follow the density, chemical abundances, and temperature of gas in the central regions of dark matter halos, including hierarchical growth and an evolving LW background. We begin by studying the physics of halos subjected...

  1. A Flat Universe from High-Resolution Maps of the Cosmic MicrowaveBackground Radiation

    Energy Technology Data Exchange (ETDEWEB)

    de Bernardis, P.; Ade, P.A.R.; Bock, J.J.; Bond, J.R.; Borrill,J.; Boscaleri, A.; Coble, K.; Crill, B.P.; De Gasperis, G.; Farese, P.C.; Ferreira, P.G.; Ganga, K.; Giacometti, M.; Hivon, E.; Hristov, V.V.; Iacoangeli, A.; Jaffe, A.H.; Lange, A.E.; Martinis, L.; Masi, S.; Mason,P.; Mauskopf, P.D.; Melchiorri, A.; Miglio, L.; Montroy, T.; Netterfield,C.B.; Pascale, E.; Piacentini, F.; Pogosyan, D.; Prunet, S.; Rao, S.; Romeo, G.; Ruhl, J.E.; Scaramuzzi, F.; Sforna, D.; Vittorio, N.

    2000-04-28

    The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K Cosmic Microwave Background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole {ell}{sub peak} = (197 {+-} 6), with an amplitude DT{sub 200} = (69 {+-} 8){mu}K. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favored by standard inflationary scenarios.

  2. Radio-loud AGNs at high redshifts and the cosmic microwave background

    CERN Document Server

    Ghisellini, G; Tavecchio, F; Haardt, F; Sbarrato, T

    2013-01-01

    We discuss how the interaction between the electrons in a relativistic jet and the Cosmic Microwave Background (CMB) affects the observable properties of radio-loud AGN at early epochs. At high z the magnetic energy density in the radio lobes of powerful radio-loud quasars can be exceeded by the energy density of the CMB (because of its (1+z)^4 dependance). In this case, relativistic electrons cool preferentially by scattering off CMB photons, rather than by synchrotron. Thus, sources sharing the same intrinsic properties have different extended radio and X-ray luminosities when located at different z: more distant sources are less luminous in radio and more luminous in X-rays than their closer counterparts. Instead, in compact regions where the local magnetic field still exceeds the CMB in terms of energy density, synchrotron radiation would be unaffected by the presence of the CMB. Such regions include the compact inner jet and the so-called hot spots in the radio lobes. The decrease in radio luminosity is ...

  3. High-impedence NbSi TES sensors for studying the cosmic microwave background radiation

    CERN Document Server

    Nones, Claudia; Benoit, Alain; Bergé, Laurent; Bideau, Aurelien; Camus, Philippe; Dumoulin, Louis; Monfardini, Alessandro; Rigaut, Olivier

    2012-01-01

    Precise measurements of the cosmic microwave background (CMB) are crucial in cosmology, because any proposed model of the universe must account for the features of this radiation. Of all CMB measurements that the scientific community has not yet been able to perform, the CMB B-mode polarization is probably the most challenging from the instrumental point of view. The signature of primordial gravitational waves, which give rise to a B-type polarization, is one of the goals in cosmology today and amongst the first objectives in the field. For this purpose, high-performance low-temperature bolometric cameras, made of thousands of pixels, are currently being developed by many groups, which will improve the sensitivity to B-mode CMB polarization by one or two orders of magnitude compared to the Planck satellite HFI detectors. We present here a new bolometer structure that is able to increase the pixel sensitivities and to simplify the fabrication procedure. This innovative device replaces delicate membrane-based s...

  4. Low background high efficiency radiocesium detection system based on positron emission tomography technology

    Science.gov (United States)

    Yamamoto, Seiichi; Ogata, Yoshimune

    2013-09-01

    After the 2011 nuclear power plant accident at Fukushima, radiocesium contamination in food became a serious concern in Japan. However, low background and high efficiency radiocesium detectors are expensive and huge, including semiconductor germanium detectors. To solve this problem, we developed a radiocesium detector by employing positron emission tomography (PET) technology. Because 134Cs emits two gamma photons (795 and 605 keV) within 5 ps, they can selectively be measured with coincidence. Such major environmental gamma photons as 40K (1.46 MeV) are single photon emitters and a coincidence measurement reduces the detection limit of radiocesium detectors. We arranged eight sets of Bi4Ge3O12 (BGO) scintillation detectors in double rings (four for each ring) and measured the coincidence between these detectors using PET data acquisition system. A 50 × 50 × 30 mm BGO was optically coupled to a 2 in. square photomultiplier tube (PMT). By measuring the coincidence, we eliminated most single gamma photons from the energy distribution and only detected those from 134Cs at an average efficiency of 12%. The minimum detectable concentration of the system for the 100 s acquisition time is less than half of the food monitor requirements in Japan (25 Bq/kg). These results show that the developed radiocesium detector based on PET technology is promising to detect low level radiocesium.

  5. Low background high efficiency radiocesium detection system based on positron emission tomography technology

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi; Ogata, Yoshimune [Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya 461-8673 (Japan)

    2013-09-15

    After the 2011 nuclear power plant accident at Fukushima, radiocesium contamination in food became a serious concern in Japan. However, low background and high efficiency radiocesium detectors are expensive and huge, including semiconductor germanium detectors. To solve this problem, we developed a radiocesium detector by employing positron emission tomography (PET) technology. Because {sup 134}Cs emits two gamma photons (795 and 605 keV) within 5 ps, they can selectively be measured with coincidence. Such major environmental gamma photons as {sup 40}K (1.46 MeV) are single photon emitters and a coincidence measurement reduces the detection limit of radiocesium detectors. We arranged eight sets of Bi{sub 4}Ge{sub 3}O{sub 12} (BGO) scintillation detectors in double rings (four for each ring) and measured the coincidence between these detectors using PET data acquisition system. A 50 × 50 × 30 mm BGO was optically coupled to a 2 in. square photomultiplier tube (PMT). By measuring the coincidence, we eliminated most single gamma photons from the energy distribution and only detected those from {sup 134}Cs at an average efficiency of 12%. The minimum detectable concentration of the system for the 100 s acquisition time is less than half of the food monitor requirements in Japan (25 Bq/kg). These results show that the developed radiocesium detector based on PET technology is promising to detect low level radiocesium.

  6. Fluctuations in radiation backgrounds at high redshift and the first stars

    Science.gov (United States)

    Holzbauer, Lauren Nicole

    The first stars to light up our universe are as yet unseen, but there have been many attempts to elucidate their properties. The characteristics of these stars (`Population/Pop III' stars) that we do know lie mostly within theory; they formed out of metal-free hydrogen and helium gas contained in dark matter minihalos at redshifts z 20-30. The extent to which Pop III star formation reached into later times is unknown. Current and near future instruments are incapable of resolving individual Pop III stars. Consequently, astronomers must devise creative means with which to indirectly predict and measure and their properties. In this thesis, we will investigate a few of those means. We use a new method to model fluctuations of the Lyman-Werner (LW) and Lyman-alpha radiation backgrounds at high redshift. At these early epochs the backgrounds are symptoms of a universe newly lit with its first stars. LW photons (11.5-13.6 eV) are of particular interest because they dissociate molecular hydrogen, the primary coolant in the first minihalos that is necessary for star formation. By using a variation of the `halo model', which describes the spatial distribution and clustering of halos, we can efficiently generate power spectra for these backgrounds. Spatial fluctuations in the LW and (indirectly) the Lyman-alpha BG can tell us about the transition from primordial star formation to a more metal-enriched mode that marks the beginning of the second generation of stars in our Universe. The Near Infrared Background (NIRB) has for some time been considered a potential tool with which to indirectly observe the first stars. Ultraviolet (UV) emission from these stars is redshifted into the NIR band, making the NIRB amenable for hunting Pop III stellar signatures. There have been several measurements of the NIRB and subsequent theoretical studies attempting to explain them in recent years. Though controversial, residual levels of the mean NIRB intensity and anisotropies have been

  7. Experimental test of the background rejection, through imaging capability, of a highly segmented AGATA germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Doncel, M., E-mail: doncel@usal.e [Laboratorio de Radiaciones Ionizantes, Universidad de Salamanca (Spain); Recchia, F. [INFN sezione di Padova, Padova (Italy); Quintana, B. [Laboratorio de Radiaciones Ionizantes, Universidad de Salamanca (Spain); Gadea, A. [IFIC Valencia, Valencia (Spain); INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Farnea, E. [INFN sezione di Padova, Padova (Italy)

    2010-10-21

    The development of highly segmented germanium detectors as well as the algorithms to identify the position of the interaction within the crystal opens the possibility to locate the {gamma}-ray source using Compton imaging algorithms. While the Compton-suppression shield, coupled to the germanium detector in conventional arrays, works also as an active filter against the {gamma} rays originated outside the target, the new generation of position sensitive {gamma}-ray detector arrays has to fully rely on tracking capabilities for this purpose. In specific experimental conditions, as the ones foreseen at radioactive beam facilities, the ability to discriminate background radiation improves the sensitivity of the gamma spectrometer. In this work we present the results of a measurement performed at the Laboratori Nazionali di Legnaro (LNL) aiming the evaluation of the AGATA detector capabilities to discriminate the origin of the {gamma} rays on an event-by-event basis. It will be shown that, exploiting the Compton scattering formula, it is possible to track back {gamma} rays coming from different positions, assigning them to specific emitting locations. These imaging capabilities are quantified for a single crystal AGATA detector.

  8. In situ electrochemical impedance and noise measurements of corroding stainless steel in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Macak, Jan [Power Engineering Department, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)]. E-mail: macakj@vscht.cz; Sajdl, Petr [Power Engineering Department, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Kucera, Pavel [Power Engineering Department, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Novotny, Radek [Institute for Energy, Joint Research Centre, 1755ZG Petten (Netherlands); Vosta, Jan [Power Engineering Department, Institute of Chemical Technology Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2006-04-25

    An in situ corrosion study of austenitic stainless steel 08CH18N10T in high temperature water was performed. The material under study is used in the construction of steam generator of PWR (pressurized water reactor) nuclear power stations and is similar to AISI 321 stainless steel. In situ 300-h tests were performed under autoclave conditions at 280 deg. C and 8 MPa and consisted of impedance measurements, polarization measurements and electrochemical noise measurements. The experiments were performed in deionised water with the pH adjusted to 9.5, in the presence/absence of chlorides. An additional modification of corrosivity was achieved by changing oxygen concentration. A detailed analysis of the impedance data is presented identifying in the impedance spectra contributions of oxide, corrosion reaction, double layer and diffusion process. A good agreement was found between corrosion data from electrochemical impedance spectroscopy (EIS) and that from electrochemical noise (EN) measurements. It was confirmed that the oxide response cannot be attributed to the overall oxide layer but only to the part corresponding to the space charge layer, thus indicating the semi-conductive character of the oxide.

  9. Human exposure to high natural background radiation: what can it teach us about radiation risks?

    Energy Technology Data Exchange (ETDEWEB)

    Hendry, Jolyon H; Sohrabi, Mehdi; Burkart, Werner [Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna (Austria); Simon, Steven L [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD (United States); Wojcik, Andrzej [Institute of Nuclear Chemistry and Technology, Warsaw (Poland); Cardis, Elisabeth [Centre for Research in Environmental Epidemiology (CREAL), Municipal Institute of Medical Research (IMIM-Hospital del Mar) and CIBER Epidemiologia y Salud Publica - CIBERESP, Barcelona (Spain); Laurier, Dominique; Tirmarche, Margot [Radiobiology and Epidemiology Department, Radiological and Human Health Division, Institute for Radiological Protection and Nuclear Safety, Fontenay-aux-Roses (France); Hayata, Isamu [National Institute of Radiological Sciences, Chiba (Japan)], E-mail: jhendry2002uk@yahoo.com

    2009-06-01

    Natural radiation is the major source of human exposure to ionising radiation, and its largest contributing component to effective dose arises from inhalation of {sup 222}Rn and its radioactive progeny. However, despite extensive knowledge of radiation risks gained through epidemiologic investigations and mechanistic considerations, the health effects of chronic low-level radiation exposure are still poorly understood. The present paper reviews the possible contribution of studies of populations living in high natural background radiation (HNBR) areas (Guarapari, Brazil; Kerala, India; Ramsar, Iran; Yangjiang, China), including radon-prone areas, to low dose risk estimation. Much of the direct information about risk related to HNBR comes from case-control studies of radon and lung cancer, which provide convincing evidence of an association between long-term protracted radiation exposures in the general population and disease incidence. The success of these studies is mainly due to the careful organ dose reconstruction (with relatively high doses to the lung), and to the fact that large-scale collaborative studies have been conducted to maximise the statistical power and to ensure the systematic collection of information on potential confounding factors. In contrast, studies in other (non-radon) HNBR areas have provided little information, relying mainly on ecological designs and very rough effective dose categorisations. Recent steps taken in China and India to establish cohorts for follow-up and to conduct nested case-control studies may provide useful information about risks in the future, provided that careful organ dose reconstruction is possible and information is collected on potential confounding factors.

  10. Human exposure to high natural background radiation: what can it teach us about radiation risks?

    Science.gov (United States)

    Hendry, Jolyon H; Simon, Steven L; Wojcik, Andrzej; Sohrabi, Mehdi; Burkart, Werner; Cardis, Elisabeth; Laurier, Dominique; Tirmarche, Margot; Hayata, Isamu

    2009-06-01

    Natural radiation is the major source of human exposure to ionising radiation, and its largest contributing component to effective dose arises from inhalation of (222)Rn and its radioactive progeny. However, despite extensive knowledge of radiation risks gained through epidemiologic investigations and mechanistic considerations, the health effects of chronic low-level radiation exposure are still poorly understood. The present paper reviews the possible contribution of studies of populations living in high natural background radiation (HNBR) areas (Guarapari, Brazil; Kerala, India; Ramsar, Iran; Yangjiang, China), including radon-prone areas, to low dose risk estimation. Much of the direct information about risk related to HNBR comes from case-control studies of radon and lung cancer, which provide convincing evidence of an association between long-term protracted radiation exposures in the general population and disease incidence. The success of these studies is mainly due to the careful organ dose reconstruction (with relatively high doses to the lung), and to the fact that large-scale collaborative studies have been conducted to maximise the statistical power and to ensure the systematic collection of information on potential confounding factors. In contrast, studies in other (non-radon) HNBR areas have provided little information, relying mainly on ecological designs and very rough effective dose categorisations. Recent steps taken in China and India to establish cohorts for follow-up and to conduct nested case-control studies may provide useful information about risks in the future, provided that careful organ dose reconstruction is possible and information is collected on potential confounding factors.

  11. Noise characteristics of CT perfusion imaging: how does noise propagate from source images to final perfusion maps?

    Science.gov (United States)

    Li, Ke; Chen, Guang-Hong

    2016-03-01

    Cerebral CT perfusion (CTP) imaging is playing an important role in the diagnosis and treatment of acute ischemic strokes. Meanwhile, the reliability of CTP-based ischemic lesion detection has been challenged due to the noisy appearance and low signal-to-noise ratio of CTP maps. To reduce noise and improve image quality, a rigorous study on the noise transfer properties of CTP systems is highly desirable to provide the needed scientific guidance. This paper concerns how noise in the CTP source images propagates to the final CTP maps. Both theoretical deviations and subsequent validation experiments demonstrated that, the noise level of background frames plays a dominant role in the noise of the cerebral blood volume (CBV) maps. This is in direct contradiction with the general belief that noise of non-background image frames is of greater importance in CTP imaging. The study found that when radiation doses delivered to the background frames and to all non-background frames are equal, lowest noise variance is achieved in the final CBV maps. This novel equality condition provides a practical means to optimize radiation dose delivery in CTP data acquisition: radiation exposures should be modulated between background frames and non-background frames so that the above equality condition is satisïnAed. For several typical CTP acquisition protocols, numerical simulations and in vivo canine experiment demonstrated that noise of CBV can be effectively reduced using the proposed exposure modulation method.

  12. High-Frequency Transcranial Random Noise Stimulation Enhances Perception of Facial Identity.

    Science.gov (United States)

    Romanska, Aleksandra; Rezlescu, Constantin; Susilo, Tirta; Duchaine, Bradley; Banissy, Michael J

    2015-11-01

    Recently, a number of studies have demonstrated the utility of transcranial current stimulation as a tool to facilitate a variety of cognitive and perceptual abilities. Few studies, though, have examined the utility of this approach for the processing of social information. Here, we conducted 2 experiments to explore whether a single session of high-frequency transcranial random noise stimulation (tRNS) targeted at lateral occipitotemporal cortices would enhance facial identity perception. In Experiment 1, participants received 20 min of active high-frequency tRNS or sham stimulation prior to completing the tasks examining facial identity perception or trustworthiness perception. Active high-frequency tRNS facilitated facial identity perception, but not trustworthiness perception. Experiment 2 assessed the spatial specificity of this effect by delivering 20 min of active high-frequency tRNS to lateral occipitotemporal cortices or sensorimotor cortices prior to participants completing the same facial identity perception task used in Experiment 1. High-frequency tRNS targeted at lateral occipitotemporal cortices enhanced performance relative to motor cortex stimulation. These findings show that high-frequency tRNS to lateral occipitotemporal cortices produces task-specific and site-specific enhancements in face perception.

  13. Background observations on the SMM high energy monitor at energies greater than 10 MeV

    Science.gov (United States)

    Forrest, D. J.

    1989-01-01

    The background rate in any gamma ray detector on a spacecraft in near-earth orbit is strongly influenced by the primary cosmic ray flux at the spacecraft's position. Although the direct counting of the primary cosmic rays can be rejected by anticoincident shields, secondary production cannot be. Secondary production of gamma rays and neutrons in the instrument, the spacecraft, and the earth's atmospheric are recorded as background. A 30 day data base of 65.5 second records has been used to show that some of the background rates observed on the Gamma Ray Spectrometer can be ordered to a precision on the order of 1 percent This ordering is done with only two parameters, namely the cosmic ray vertical cutoff rigidity and the instrument's pointing angle with respect to the earth's center. This result sets limits on any instrumental instability and also on any temporal or spatial changes in the background radiation field.

  14. The functions of culture background knowledge in improving English reading in high school

    Institute of Scientific and Technical Information of China (English)

    乌日乐

    2014-01-01

    This paper argues that by strengthening awareness of students 'background knowledge can improve students'reading results .By testing ex-periments, surveys, all the data collected were analyzed . Experimental tests and surveys which are carried out in all the students . And contrast the Chinese culture and foreign culture;through all of the things found background knowledge can promote the sustainable develop -ment of the students'English reading , so there are many important practical significances and values to explore .

  15. Qualifying plasma diagnostics for a high power microwave background of ECRH heated discharges

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, M.; Baldzuhn, J.; Endler, M.; Laux, M.; Zhang, D.; Laqua, H.P.; Noke, F.; Purps, F.; Ewert, K. [Max-Planck Institut fur Plasmaphysik, EURATOM Association, D-17491 Greifswald (Germany); Oosterbeek, J.W. [Technische Universiteit Eindhoven, Den Doelch 2, 5612 AZ Eindhoven (Netherlands); Jimenez, R. [Associacion EURATOM/CIEMAT, av. Complutense 22, 28040, Madrid (Spain)

    2011-07-01

    Microwave background radiation resulting from multiple reflected unabsorbed ECRH / ECCD power may cause severe problems for microwave absorbing in-vessel components such as gaskets, bellows, windows, isolators and cable insulations in particular during long pulse operation. For qualifying in-vessel components of W7-X in the environment of an isotropic 140 GHz radiation the Microwave Stray Radiation Launch facility, MISTRAL is operated at IPP. Power flux densities of 10-40 kW/m{sup 2} are obtained with a pulsed power gyrotron launching the microwave via a corrugated transmission line and a vacuum window to the MISTRAL vessel. The focus of the program was on cable isolations as required e.g. for in-vessel magnetic diagnostics. Sufficient shielding is obtained in nearly closed metal pipes only. Cryo pumps require a temperature < 12 K where Hydrogen desorption starts. The cryo pumps are usually shielded from plasma radiation by so called chevron structures. It is investigated whether coating of these chevrons with a microwave absorbing layer yields a sufficient reduction of the stray radiation level to ensure cryo pump operation. Diagnostic windows have been tested also. Although the temperature rise even of uncooled ZnSe and quartz windows at 10 kW/m{sup 2} is uncritical with respect to damage the associated refractive index changes may be too high for some diagnostic purposes e.g. for interferometry. A possible shielding are meshes or {mu}W absorbing coatings. Integrated diagnostic mock-ups such as for the diamagnetic loop, the inner Rogowski coils, Mirnov coils and the bolometer head also have been tested

  16. High Prevalence of Smoking in the Roma Population Seems to Have No Genetic Background.

    Science.gov (United States)

    Fiatal, Szilvia; Tóth, Réka; Moravcsik-Kornyicki, Ágota; Kósa, Zsigmond; Sándor, János; McKee, Martin; Ádány, Róza

    2016-12-01

    The prevalence of smoking in Romani of both genders is significantly higher than in the general population. Our aim was to determine whether a genetic susceptibility contributes to the high prevalence of smoking among Roma in a study based on data collected from cross-sectional surveys. Twenty single nucleotide polymorphisms known to be closely related to smoking behavior were investigated in DNA samples of Hungarian Roma (N = 1273) and general (N = 2388) populations. Differences in genotype and allele distribution were investigated. Genetic risk scores (GRSs) were generated to estimate the joint effect of single nucleotide polymorphisms in genes COMT, CHRNA3/4/5, CYP2A6, CTNNA3, DRD2, MAOA, KCNJ6, AGPHD1, ANKK1, TRPC7, GABRA4, and NRXN1. The distribution of scores in study populations was compared. Age, gender, and body mass index were considered as confounding factors. Difference in allele frequencies between the study populations remained significant for 16 polymorphisms after multiple test correction (p smoking behavior of the Roma population could not be accounted for by genetic susceptibility; therefore, interventions aimed at smoking prevention and cessation should focus on cultural and environmental factors. This is the first study designed to determine whether genetic background exists behind the harmful behavior of the smoking of the Roma population. Although the frequencies of susceptible and protective alleles strongly differ between the Hungarian Roma and general populations, it is shown that calculated GRSs being significantly higher in the general population, which do not support the hypothesis on the genetic susceptibility of the Roma population. Interventions aimed at smoking cessation in the Roma population should preferentially target cultural and environmental factors. © The Author 2016. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e

  17. Multilocus spacer analysis revealed highly homogeneous genetic background of Asian type of Borrelia miyamotoi.

    Science.gov (United States)

    Mukhacheva, Tatyana A; Salikhova, Irina I; Kovalev, Sergey Y

    2015-04-01

    Borrelia miyamotoi, a member of the relapsing fever group borreliae, was first isolated in Japan and subsequently found in Ixodes ticks in North America, Europe and Russia. Currently, there are three types of B. miyamotoi: Asian or Siberian (transmitted mainly by Ixodes persulcatus), European (Ixodesricinus) and American (Ixodesscapularis and Ixodespacificus). Despite the great genetic distances between B. miyamotoi types, isolates within a type are characterised by an extremely low genetic variability. In particular, strains of B. miyamotoi of Asian type, isolated in Russia from the Baltic sea to the Far East, have been shown to be identical based on the analysis of several conventional genetic markers, such as 16S rRNA, flagellin, outer membrane protein p66 and glpQ genes. Thus, protein or rRNA - coding genes were shown not to be informative enough in studying genetic diversity of B. miyamotoi within a type. In the present paper, we have attempted to design a new multilocus technique based on eight non-coding intergenic spacers (3686bp in total) and have applied it to the analysis of intra-type genetic variability of В. miyamotoi detected in different regions of Russia and from two tick species, I. persulcatus and Ixodespavlovskyi. However, even though potentially the most variable loci were selected, no genetic variability between studied DNA samples was found, except for one nucleotide substitution in two of them. The sequences obtained were identical to those of the reference strain FR64b. Analysis of the data obtained with the GenBank sequences indicates a highly homogeneous genetic background of B. miyamotoi from the Baltic Sea to the Japanese Islands. In this paper, a hypothesis of clonal expansion of B. miyamotoi is discussed, as well as possible mechanisms for the rapid dissemination of one B. miyamotoi clone over large distances.

  18. Noise-free high-efficiency photon-number-resolving detectors

    CERN Document Server

    Rosenberg, D; Miller, A J; Nam, S W; Rosenberg, Danna; Lita, Adriana E.; Miller, Aaron J.; Nam, Sae Woo

    2005-01-01

    High-efficiency optical detectors that can determine the number of photons in a pulse of monochromatic light have applications in a variety of physics studies, including post-selection-based entanglement protocols for linear optics quantum computing and experiments that simultaneously close the detection and communication loopholes of Bell's inequalities. Here we report on our demonstration of fiber-coupled, noise-free, photon-number-resolving transition-edge sensors with 88% efficiency at 1550 nm. The efficiency of these sensors could be made even higher at any wavelength in the visible and near-infrared spectrum without resulting in a higher dark-count rate or degraded photon-number resolution.

  19. Annoyance to Noise Produced by a Distributed Electric Propulsion High-Lift System

    Science.gov (United States)

    Rizzi, Stephen A.; Palumbo, Daniel L.; Rathsam, Jonathan; Christian, Andrew; Rafaelof, Menachem

    2017-01-01

    A psychoacoustic test was performed using simulated sounds from a distributed electric propulsion aircraft concept to help understand factors associated with human annoyance. A design space spanning the number of high-lift leading edge propellers and their relative operating speeds, inclusive of time varying effects associated with motor controller error and atmospheric turbulence, was considered. It was found that the mean annoyance response varies in a statistically significant manner with the number of propellers and with the inclusion of time varying effects, but does not differ significantly with the relative RPM between propellers. An annoyance model was developed, inclusive of confidence intervals, using the noise metrics of loudness, roughness, and tonality as predictors.

  20. Modeling of low- and high-frequency noise by slow and fast fluctuators

    Science.gov (United States)

    Nesterov, Alexander I.; Berman, Gennady P.

    2012-05-01

    We study the dynamics of dephasing in a quantum two-level system by modeling both 1/f and high-frequency noise by random telegraph processes. Our approach is based on a so-called spin-fluctuator model in which a noisy environment is modeled by a large number of fluctuators. In the continuous limit we obtain an effective random process (ERP) that is described by a distribution function of the fluctuators. In a simplified model, we reduce the ERP to the two (slow and fast) ensembles of fluctuators. Using this model, we study decoherence in a superconducting flux qubit and we compare our theoretical results with the available experimental data. We demonstrate good agreement of our theoretical predictions with the experiments. Our approach can be applied to many quantum systems, such as biological complexes, semiconductors, superconducting, and spin qubits, where the effects of interaction with the environment are essential.

  1. Microstructures and Crackling Noise of AlxNbTiMoV High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Shu Ying Chen

    2014-02-01

    Full Text Available A series of high entropy alloys (HEAs, AlxNbTiMoV, was produced by a vacuum arc-melting method. Their microstructures and compressive mechanical behavior at room temperature were investigated. It has been found that a single solid-solution phase with a body-centered cubic (BCC crystal structure forms in these alloys. Among these alloys, Al0.5NbTiMoV reaches the highest yield strength (1,625 MPa, which should be attributed to the considerable solid-solution strengthening behavior. Furthermore, serration and crackling noises near the yielding point was observed in the NbTiMoV alloy, which represents the first such reported phenomenon at room temperature in HEAs.

  2. Modeling of Low and High Frequency Noise by Slow and Fast Fluctuators

    CERN Document Server

    Nesterov, Alexander I

    2012-01-01

    We study the dynamics of dephasing in a quantum two-level system by modeling both $1/f$ and high-frequency noise by random telegraph processes. Our approach is based on a so-called spin-fluctuator model in which a noisy environment is modelled by a large number of fluctuators. In the continuous limit we obtain an effective random process (ERP) that is described by a distribution function of the fluctuators. In a simplified model, we reduce the ERP to the two (slow and fast) effective fluctuators. Using this model, we study decoherence in a superconducting flux qubit and we compare our theoretical results with the available experimental data. We demonstrate good agreement of our theoretical predictions with the experiments. Our approach can be applied to many quantum systems, such as photosynthetic complexes, semiconductors, and superconducting and spin qubits, where the effects of interaction with the environment are essential.

  3. Prevalence of high frequency hearing loss consistent with noise exposure among people working with sound systems and general population in Brazil: A cross-sectional study

    Directory of Open Access Journals (Sweden)

    Trevisani Virgínia FM

    2008-05-01

    Full Text Available Abstract Background Music is ever present in our daily lives, establishing a link between humans and the arts through the senses and pleasure. Sound technicians are the link between musicians and audiences or consumers. Recently, general concern has arisen regarding occurrences of hearing loss induced by noise from excessively amplified sound-producing activities within leisure and professional environments. Sound technicians' activities expose them to the risk of hearing loss, and consequently put at risk their quality of life, the quality of the musical product and consumers' hearing. The aim of this study was to measure the prevalence of high frequency hearing loss consistent with noise exposure among sound technicians in Brazil and compare this with a control group without occupational noise exposure. Methods This was a cross-sectional study comparing 177 participants in two groups: 82 sound technicians and 95 controls (non-sound technicians. A questionnaire on music listening habits and associated complaints was applied, and data were gathered regarding the professionals' numbers of working hours per day and both groups' hearing complaint and presence of tinnitus. The participants' ear canals were visually inspected using an otoscope. Hearing assessments were performed (tonal and speech audiometry using a portable digital AD 229 E audiometer funded by FAPESP. Results There was no statistically significant difference between the sound technicians and controls regarding age and gender. Thus, the study sample was homogenous and would be unlikely to lead to bias in the results. A statistically significant difference in hearing loss was observed between the groups: 50% among the sound technicians and 10.5% among the controls. The difference could be addressed to high sound levels. Conclusion The sound technicians presented a higher prevalence of high frequency hearing loss consistent with noise exposure than did the general population, although

  4. A full-spectrum analysis of high-speed train interior noise under multi-physical-field coupling excitations

    Science.gov (United States)

    Zheng, Xu; Hao, Zhiyong; Wang, Xu; Mao, Jie

    2016-06-01

    High-speed-railway-train interior noise at low, medium, and high frequencies could be simulated by finite element analysis (FEA) or boundary element analysis (BEA), hybrid finite element analysis-statistical energy analysis (FEA-SEA) and statistical energy analysis (SEA), respectively. First, a new method named statistical acoustic energy flow (SAEF) is proposed, which can be applied to the full-spectrum HST interior noise simulation (including low, medium, and high frequencies) with only one model. In an SAEF model, the corresponding multi-physical-field coupling excitations are firstly fully considered and coupled to excite the interior noise. The interior noise attenuated by sound insulation panels of carriage is simulated through modeling the inflow acoustic energy from the exterior excitations into the interior acoustic cavities. Rigid multi-body dynamics, fast multi-pole BEA, and large-eddy simulation with indirect boundary element analysis are first employed to extract the multi-physical-field excitations, which include the wheel-rail interaction forces/secondary suspension forces, the wheel-rail rolling noise, and aerodynamic noise, respectively. All the peak values and their frequency bands of the simulated acoustic excitations are validated with those from the noise source identification test. Besides, the measured equipment noise inside equipment compartment is used as one of the excitation sources which contribute to the interior noise. Second, a full-trimmed FE carriage model is firstly constructed, and the simulated modal shapes and frequencies agree well with the measured ones, which has validated the global FE carriage model as well as the local FE models of the aluminum alloy-trim composite panel. Thus, the sound transmission loss model of any composite panel has indirectly been validated. Finally, the SAEF model of the carriage is constructed based on the accurate FE model and stimulated by the multi-physical-field excitations. The results show

  5. Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Jannis Lübbe

    2013-01-01

    Full Text Available The noise of the frequency-shift signal Δf in noncontact atomic force microscopy (NC-AFM consists of cantilever thermal noise, tip–surface-interaction noise and instrumental noise from the detection and signal processing systems. We investigate how the displacement-noise spectral density dz at the input of the frequency demodulator propagates to the frequency-shift-noise spectral density dΔf at the demodulator output in dependence of cantilever properties and settings of the signal processing electronics in the limit of a negligible tip–surface interaction and a measurement under ultrahigh-vacuum conditions. For a quantification of the noise figures, we calibrate the cantilever displacement signal and determine the transfer function of the signal-processing electronics. From the transfer function and the measured dz, we predict dΔf for specific filter settings, a given level of detection-system noise spectral density dzds and the cantilever-thermal-noise spectral density dzth. We find an excellent agreement between the calculated and measured values for dΔf. Furthermore, we demonstrate that thermal noise in dΔf, defining the ultimate limit in NC-AFM signal detection, can be kept low by a proper choice of the cantilever whereby its Q-factor should be given most attention. A system with a low-noise signal detection and a suitable cantilever, operated with appropriate filter and feedback-loop settings allows room temperature NC-AFM measurements at a low thermal-noise limit with a significant bandwidth.

  6. Characterization of High-Power Rocket and Jet Noise Using Near-Field Acoustical Holography

    OpenAIRE

    2010-01-01

    Structural fatigue, hearing damage, and community disturbances are all consequences of rocket and jet noise, especially as they become more powerful. Noise-reduction schemes require accurate characterization of the noise sources within rocket plumes and jets. Nearfield acoustical holography (NAH) measurements were made to visualize the sound field in the jet exhaust region of an F-22 Raptor. This is one of the largest-scale applications of NAH since its development in the 1980s. A scan-based ...

  7. Visual recovery in cortical blindness is limited by high internal noise.

    Science.gov (United States)

    Cavanaugh, Matthew R; Zhang, Ruyuan; Melnick, Michael D; Das, Anasuya; Roberts, Mariel; Tadin, Duje; Carrasco, Marisa; Huxlin, Krystel R

    2015-01-01

    Damage to the primary visual cortex typically causes cortical blindness (CB) in the hemifield contralateral to the damaged hemisphere. Recent evidence indicates that visual training can partially reverse CB at trained locations. Whereas training induces near-complete recovery of coarse direction and orientation discriminations, deficits in fine motion processing remain. Here, we systematically disentangle components of the perceptual inefficiencies present in CB fields before and after coarse direction discrimination training. In seven human CB subjects, we measured threshold versus noise functions before and after coarse direction discrimination training in the blind field and at corresponding intact field locations. Threshold versus noise functions were analyzed within the framework of the linear amplifier model and the perceptual template model. Linear amplifier model analysis identified internal noise as a key factor differentiating motion processing across the tested areas, with visual training reducing internal noise in the blind field. Differences in internal noise also explained residual perceptual deficits at retrained locations. These findings were confirmed with perceptual template model analysis, which further revealed that the major residual deficits between retrained and intact field locations could be explained by differences in internal additive noise. There were no significant differences in multiplicative noise or the ability to process external noise. Together, these results highlight the critical role of altered internal noise processing in mediating training-induced visual recovery in CB fields, and may explain residual perceptual deficits relative to intact regions of the visual field.

  8. Ultrahigh Energy Cosmic Rays, The Diffuse High Energy Gamma Ray Background and Anti-protons

    CERN Document Server

    Eichler, David; Gavish, Eyal

    2016-01-01

    Theories for the origin of ultrahigh energy cosmic rays (UHECR) may imply a significant diffuse background in secondary $\\gamma$-rays from the pair cascads the UHECR initiate when interacting with background light. It is shown that, because the spectrum of these secondary $\\gamma$-rays is softer than the measured diffuse $\\gamma$-ray background in the 10-1000 GeV range, the addition of a hard component from the decay of TeV dark matter particles, subject to the implied constraints on its parameters, improves the fit. It is further argued that any compact astrophysical source of $\\bar p$s is unlikely to be as strong as decay of TeV dark matter particles, given bounds set by neutrino observations. The diffuse $\\gamma$-ray background presently sets the strongest lower bound on the lifetime of TeV dark matter particles, and hence on attendant anti-proton production, and further identification of other contributors to this background will further tighten these constraints.

  9. Development of an underground low background instrument for high sensitivity measurements

    Science.gov (United States)

    Sala, E.; Hahn, I. S.; Kang, W. G.; Kim, G. W.; Kim, Y. D.; Lee, M. H.; Leonard, D. S.; Park, Su Yeon

    2016-05-01

    The Center for Underground Physics has developed in collaboration with CANBERRA a low background instrument composed of 14 HPGe detectors divided in two arrays facing each other. The performance and the background of a single detector of the array have been studied in order to improve the array final configuration. An accurate material selection, through the measurements of building material samples and Monte Carlo simulations based on Geant4, has been performed to reach the lowest possible intrinsic background. Alternative materials and configurations have been considered for the final design of the array simulating the expected intrinsic background of the instrument considering the needed changes. The expected sensitivity of the improved array configuration, concerning the low background material selection for rare events physics experiments, has been evaluated through Monte Carlo simulations considering 232Th concentration in a Copper sample. Since the array can also be used for rare decays searches, the expected sensitivity on the 156Dy resonant double electron capture has thus been calculated.

  10. Effect of Two Advanced Noise Reduction Technologies on the Aerodynamic Performance of an Ultra High Bypass Ratio Fan

    Science.gov (United States)

    Hughes, Christoper E.; Gazzaniga, John A.

    2013-01-01

    A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot Low-Speed Wind Tunnel to investigate two new advanced noise reduction technologies in support of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project. The goal of the experiment was to demonstrate the noise reduction potential and effect on fan model performance of the two noise reduction technologies in a scale model Ultra-High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two novel noise reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed at modifying the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator interaction. For the Over-the-Rotor acoustic treatment, two noise reduction configurations were investigated. The results showed that the two noise reduction technologies, Over-the-Rotor and Soft Vanes, were able to reduce the noise level of the fan model, but the Over-the-Rotor configurations had a significant negative impact on the fan aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75 to 8.75 percent, depending on configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the Soft Vanes showed that there was no measurable change in the corrected fan thrust and a 1.8 percent loss in corrected stator vane thrust, which resulted in a total net thrust loss of approximately 0.5 percent compared with the baseline reference stator vane set.

  11. New decision-based trimmed median filter for high-density salt-and-pepper noise removal in images

    Science.gov (United States)

    Vijaykumar, Vaithiyam Rengarajan; Santhanamari, Guru

    2014-05-01

    A new switching-based trimmed median filter to remove high-density salt-and-pepper noise in digital images is proposed. Initially, a 3×3 sliding window is applied on each pixel in the noisy image. The minimum- and maximum-intensity values are trimmed, and the noisy pixels are detected based on the predefined threshold value. In the filtering stage, the noisy pixels are replaced by median value of uncorrupted pixels in the trimmed array. At very high noise density, if all the pixels in the sliding window are corrupted, then the proposed algorithm replaces noisy pixels by the midpoint of recently processed pixels. The experimental results for various test images show that the performance of the proposed algorithm is superior to the existing algorithms, namely SMF, WMF, CWMF, AMF, DBA, and MDBUTMF in terms of visual quality and edge preservation, even at noise levels as high as 95%.

  12. Effect of external classroom noise on schoolchildren's reading and mathematics performance: correlation of noise levels and gender.

    Science.gov (United States)

    Papanikolaou, M; Skenteris, N; Piperakis, S M

    2015-02-01

    The present study investigated the effect of low, medium, and high traffic road noise as well as irrelevant background speech noise on primary school children's reading and mathematical performance. A total of 676 participants (324 boys, 47.9% and 352 girls, 52.1%) of the 4th and 5th elementary classes participated in the project. The participants were enrolled in public primary schools from urban areas and had ages ranging from 9 to 10 years and from. Schools were selected on the basis of increasing levels of exposure to road traffic noise and then classified into three categories (Low noise: 55-66 dB, Medium noise: 67-77 dB, and High noise: 72-80 dB). We measured reading comprehension and mathematical skills in accordance with the national guidelines for elementary education, using a test designed specifically for the purpose of this study. On the one hand, children in low-level noise schools showed statistically significant differences from children in medium- and high-level noise schools in reading performance (plevel noise schools differed significantly from children in high-level noise schools but only in mathematics performance (p=0.001). Girls in general did better in reading score than boys, especially in schools with medium- and high-level noise. Finally the levels of noise and gender were found to be two independent factors.

  13. Pattern recognition of $^{136}$Xe double beta decay events and background discrimination in a high pressure Xenon TPC

    CERN Document Server

    Cebrian, S; Gomez, H; Herrera, D C; Iguaz, F J; Irastorza, I G; Luzon, G; Segui, L; Tomas, A

    2013-01-01

    High pressure gas detectors offer advantages for the detection of rare events, where background reduction is crucial. For the neutrinoless double beta decay of 136Xe a high pressure xenon gas Time Projection Chamber (TPC) combines a good energy resolution and a detailed topological information of each event. The ionization topology of the double beta decay event of 136Xe in gaseous xenon has a characteristic shape defined by the two straggling electron tracks ending up in two higher ionization charge density blobs. With a properly pixelized readout, this topological information is invaluable to perform powerful background discrimination. In this study we carry out detailed simulations of the signal topology, as well as the competing topologies from gamma events that typically compose the background at these energies. We define observables based on graph theory concepts and develop automated discrimination algorithms which reduce the background level in around three orders of magnitude while keeping signal eff...

  14. Development of High Pressure Xe Scintillation Proportional Counter for Experiments in "Low-Background" Physics

    OpenAIRE

    Akimov, D.Yu.; Burenkov, A. A; Churakov, D. L.; Kuzichev, V. F.; Morgunov, V. L.; Smirnov, G. N.; Solovov, V.N.

    1997-01-01

    Characteristics of a scintillation proportional counter with WLS fiber optics readout is described. The possibility of detection of the proportional scintillation signal produced by the single electron of primary ionization is shown. The counter can be applied for the experiments in "low--background" physics which require a low energy threshold.

  15. Low-Background Experiments with High Pressure Gas Scintillation Proportional Detector

    OpenAIRE

    Akimov, D.Yu.; Burenkov, A. A; Kuzichev, V. F.; Morgunov, V. L.; Solovov, V.N.

    1997-01-01

    A scintillation proportional counter with wavelength shifting fiber readout filled with Xe or Kr under a pressure of up to 20 atm is proposed for the low-background experiments on search for dark matter of the Universe and 2K-decay of 78 Kr.

  16. Role of Family Background, Student Behaviors, and School-Related Beliefs in Predicting High School Dropout

    Science.gov (United States)

    Parr, Alyssa K.; Bonitz, Verena S.

    2015-01-01

    The authors' purpose was to test a parsimonious model derived from social cognitive career theory (R. W. Lent, S. D. Brown, & G. Hackett, 1994) and expectancy value theory (J. S. Eccles & A. Wigfield, 2002) that integrates groups of variables (demographic background, student behaviors, and school-related beliefs) with the goal of…

  17. Combined Effects of High-Speed Railway Noise and Ground Vibrations on Annoyance.

    Science.gov (United States)

    Yokoshima, Shigenori; Morihara, Takashi; Sato, Tetsumi; Yano, Takashi

    2017-07-27

    The Shinkansen super-express railway system in Japan has greatly increased its capacity and has expanded nationwide. However, many inhabitants in areas along the railways have been disturbed by noise and ground vibration from the trains. Additionally, the Shinkansen railway emits a higher level of ground vibration than conventional railways at the same noise level. These findings imply that building vibrations affect living environments as significantly as the associated noise. Therefore, it is imperative to quantify the effects of noise and vibration exposures on each annoyance under simultaneous exposure. We performed a secondary analysis using individual datasets of exposure and community response associated with Shinkansen railway noise and vibration. The data consisted of six socio-acoustic surveys, which were conducted separately over the last 20 years in Japan. Applying a logistic regression analysis to the datasets, we confirmed the combined effects of vibration/noise exposure on noise/vibration annoyance. Moreover, we proposed a representative relationship between noise and vibration exposures, and the prevalence of each annoyance associated with the Shinkansen railway.

  18. High-frequency noise modeling of Si(Ge) bipolar transistors

    NARCIS (Netherlands)

    Vitale, F.

    2014-01-01

    The design and the optimization of electronic systems often requires a detailed knowledge of the inherent noise generated within semiconductor active devices, constituting the core of such systems. Examples of applications in which noise is a key issue include receiver front-ends in radiofrequency (

  19. Integrated covariance estimation using high-frequency data in the presence of noise

    DEFF Research Database (Denmark)

    Voev, Valeri; Lunde, Asger

    2007-01-01

    We analyze the effects of nonsynchronicity and market microstructure noise on realized covariance type estimators. Hayashi and Yoshida (2005) propose a simple estimator that resolves the problem of nonsynchronicity and is unbiased and consistent for the integrated covariance in the absence of noise...

  20. Reflection seismic imaging of a hydraulically conductive fracture zone in a high noise area, Forsmark, Sweden

    Science.gov (United States)

    Juhlin, C.; Stephens, M. B.; Cosma, C.

    2007-05-01

    High resolution reflection seismic methods have proven to be useful tools for locating fracture zones in crystalline rock. Siting of potential high-level nuclear waste repositories is a particularly important application of these methods. By using small explosive sources (15-75 grams), high resolution images of the sub-surface have been obtained in the depth range 100 m to 2 km in Sweden, Canada and elsewhere. Although ambient noise conditions in areas such as the Fennoscandian and Canadian shields are generally low, industrial noise can be high in some areas, particularly at potential sites suitable for repositories, since these are often close to existing infrastructure. In addition, the presence of this infrastructure limits the choice of sources available to the geophysicist. Forsmark, located about 140 km north of Stockholm, is one such potential site where reflection seismics have been carried out. Existing infrastructure includes nuclear reactors for power generation and a low- level waste repository. In the vicinity of the reactors, it was not possible to use an explosive source due to permitting restrictions. Instead, a VIBSIST system consisting of a tractor mounted hydraulic hammer was used in the vicinity of the reactors. By repeatedly hitting the pavement, without breaking it, at predefined sweeps and then stacking the signals, shot records comparable to explosive data could be generated. These shot records were then processed using standard methods to produce stacked sections along 3 profiles within the reactor area. Clear reflections are seen in the uppermost 600 m along 3 of these profiles. Correlation of crossing profiles shows that the strongest reflection (B8) is generated by a gently east-southeast dipping interface. Prior to construction of the reactors, several boreholes were drilled to investigate the bedrock in the area. One of these boreholes was located close to where two of the profiles cross. Projection of the B8 reflection into the

  1. Neutron detection in a high gamma-ray background with EJ-301 and EJ-309 liquid scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Stevanato, L., E-mail: luca.stevanato@pd.infn.it [Dipartimento di Fisica ed Astronomia dell' Universita di Padova, Fisica ' Galileo Galilei' , Via Marzolo 8, I-35131 Padova (Italy); Cester, D. [Dipartimento di Fisica ed Astronomia dell' Universita di Padova, Fisica ' Galileo Galilei' , Via Marzolo 8, I-35131 Padova (Italy); Nebbia, G. [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Viesti, G. [Dipartimento di Fisica ed Astronomia dell' Universita di Padova, Fisica ' Galileo Galilei' , Via Marzolo 8, I-35131 Padova (Italy)

    2012-10-21

    Using a fast digitizer, the neutron-gamma discrimination capability of the new liquid scintillator EJ-309 is compared with that obtained using standard EJ-301. Moreover the capability of both the scintillation detectors to identify a weak neutron source in a high gamma-ray background is demonstrated. The probability of neutron detection is PD=95% at 95% confidence level for a gamma-ray background corresponding to a dose rate of 100 {mu}Sv/h.

  2. Lineshape spectroscopy with a very high resolution, very high signal-to-noise crystal spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Beiersdorfer, P.; Magee, E. W.; Brown, G. V.; Chen, H.; Emig, J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hell, N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Dr. Remeis-Sternwarte & ECAP, Universität Erlangen-Nürnberg, 96049 Bamberg (Germany); Bitter, M.; Hill, K. W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Allan, P.; Brown, C. R. D.; Hill, M. P.; Hoarty, D. J.; Hobbs, L. M. R.; James, S. F. [Directorate of Research and Applied Science, AWE plc, Reading RG7 4PR (United Kingdom)

    2016-06-15

    We have developed a high-resolution x-ray spectrometer for measuring the shapes of spectral lines produced from laser-irradiated targets on the Orion laser facility. The instrument utilizes a spherically bent crystal geometry to spatially focus and spectrally analyze photons from foil or microdot targets. The high photon collection efficiency resulting from its imaging properties allows the instrument to be mounted outside the Orion chamber, where it is far less sensitive to particles, hard x-rays, or electromagnetic pulses than instruments housed close to the target chamber center in ten-inch manipulators. Moreover, Bragg angles above 50° are possible, which provide greatly improved spectral resolution compared to radially viewing, near grazing-incidence crystal spectrometers. These properties make the new instrument an ideal lineshape diagnostic for determining plasma temperature and density. We describe its calibration on the Livermore electron beam ion trap facility and present spectral data of the K-shell emission from highly charged sulfur produced by long-pulse as well as short-pulse beams on the Orion laser in the United Kingdom.

  3. High-speed imaging, acoustic features, and aeroacoustic computations of jet noise from Strombolian (and Vulcanian) explosions

    Science.gov (United States)

    Taddeucci, J.; Sesterhenn, J.; Scarlato, P.; Stampka, K.; Del Bello, E.; Pena Fernandez, J. J.; Gaudin, D.

    2014-05-01

    High-speed imaging of explosive eruptions at Stromboli (Italy), Fuego (Guatemala), and Yasur (Vanuatu) volcanoes allowed visualization of pressure waves from seconds-long explosions. From the explosion jets, waves radiate with variable geometry, timing, and apparent direction and velocity. Both the explosion jets and their wave fields are replicated well by numerical simulations of supersonic jets impulsively released from a pressurized vessel. The scaled acoustic signal from one explosion at Stromboli displays a frequency pattern with an excellent match to those from the simulated jets. We conclude that both the observed waves and the audible sound from the explosions are jet noise, i.e., the typical acoustic field radiating from high-velocity jets. Volcanic jet noise was previously quantified only in the infrasonic emissions from large, sub-Plinian to Plinian eruptions. Our combined approach allows us to define the spatial and temporal evolution of audible jet noise from supersonic jets in small-scale volcanic eruptions.

  4. Full-scale tests of reflective noise-reducing devices for balconies on high-rise buildings.

    Science.gov (United States)

    Ishizuka, Takashi; Fujiwara, Kyoji

    2013-08-01

    In the present report, the noise-shielding efficiency of balconies with ceiling-mounted reflectors on the façades of high-rise buildings is examined through full-scale field measurements. The reflectors are designed to reflect direct and diffracted waves incident on the balcony ceiling outside the balcony. Field measurements are conducted to investigate the performance of the reflectors on intermediate floors of a high-rise dwelling adjacent to a railway. The reflectors reduce railway noise by approximately 5 dB, in A-weighted sound pressure level, compared to an ordinary balcony. The noise-shielding efficiency of a balcony equipped with reflectors is greater than that of an absorbing balcony.

  5. Statistical-noise reduction in correlation analysis of high-energy nuclear collisions with event-mixing

    CERN Document Server

    Ray, R L

    2016-01-01

    The error propagation and statistical-noise reduction method of Reid and Trainor for two-point correlation applications in high-energy collisions is extended to include particle-pair references constructed by mixing two particles from all event-pair combinations within event subsets of arbitrary size. The Reid-Trainor method is also applied to other particle-pair mixing algorithms commonly used in correlation analysis of particle production from high-energy nuclear collisions. The statistical-noise reduction, inherent in the Reid-Trainor event-mixing procedure, is shown to occur for these other event-mixing algorithms as well. Monte Carlo simulation results are presented which verify the predicted degree of noise reduction. In each case the final errors are determined by the bin-wise particle-pair number, rather than by the bin-wise single-particle count.

  6. Aerodynamic noise characterization of a full-scale wind turbine through high-frequency surface pressure measurements

    DEFF Research Database (Denmark)

    Bertagnolio, Franck; Aagaard Madsen, Helge; Bak, Christian;

    2015-01-01

    The aim of this work is to investigate and characterize the high-frequency surface pressure fluctuations on a full-scale wind turbine blade and in particular the influence of the atmospheric turbulence. As these fluctuations are highly correlated to the sources of both turbulent inflow noise...... wind turbine with a 80 m diameter rotor as well as measurements of an airfoil section tested in a wind tunnel. The turbine was extensively equipped in order to monitor the local inflow onto the rotating blades. Further a section of the 38 m long blade was instrumented with 50 microphones flush......-mounted relative to the blade surface. The measurements of surface pressure spectra are compared with the results of two engineering models for trailing edge noise and for turbulent inflow noise. The measured pressure fluctuations are related to the local inflow angle and are also compared to measurements...

  7. Statistical-noise reduction in correlation analysis of high-energy nuclear collisions with event-mixing

    Energy Technology Data Exchange (ETDEWEB)

    Ray, R.L., E-mail: ray@physics.utexas.edu; Bhattarai, P.

    2016-06-11

    The error propagation and statistical-noise reduction method of Reid and Trainor for two-point correlation applications in high-energy collisions is extended to include particle-pair references constructed by mixing two particles from all event-pair combinations within event subsets of arbitrary size. The Reid–Trainor method is also applied to other particle-pair mixing algorithms commonly used in correlation analysis of particle production from high-energy nuclear collisions. The statistical-noise reduction, inherent in the Reid–Trainor event-mixing procedure, is shown to occur for these other event-mixing algorithms as well. Monte Carlo simulation results are presented which verify the predicted degree of noise reduction. In each case the final errors are determined by the bin-wise particle-pair number, rather than by the bin-wise single-particle count.

  8. Cosmic Infrared Background Fluctuations and Zodiacal Light

    CERN Document Server

    Arendt, Richard G; Moseley, S H; Mather, J

    2016-01-01

    We have performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution, or from IRAC observations of high latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field, at low ecliptic latitude where the zodiacal light intensity varies by factors of $\\sim2$ over the range of solar elongations at which the field can be observed. We find that the white noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that ...

  9. Efficient Data Averaging for Spin Noise Spectroscopy in Semiconductors

    CERN Document Server

    Müller, Georg M; Hübner, Jens; Oestreich, Michael

    2010-01-01

    Spin noise spectroscopy (SNS) is the perfect tool to investigate electron spin dynamics in semiconductors at thermal equilibrium. We simulate SNS measurements and show that ultrafast digitizers with low bit depth enable sensitive, high bandwidth SNS in the presence of strong optical background shot noise. The simulations reveal that optimized input load at the digitizer is crucial for efficient spin noise detection while the bit depth influences the sensitivity rather weakly.

  10. High power and ultra-low-noise photodetector for squeezed-light enhanced gravitational wave detectors.

    Science.gov (United States)

    Grote, Hartmut; Weinert, Michael; Adhikari, Rana X; Affeldt, Christoph; Kringel, Volker; Leong, Jonathan; Lough, James; Lück, Harald; Schreiber, Emil; Strain, Kenneth A; Vahlbruch, Henning; Wittel, Holger

    2016-09-05

    Current laser-interferometric gravitational wave detectors employ a self-homodyne readout scheme where a comparatively large light power (5-50 mW) is detected per photosensitive element. For best sensitivity to gravitational waves, signal levels as low as the quantum shot noise have to be measured as accurately as possible. The electronic noise of the detection circuit can produce a relevant limit to this accuracy, in particular when squeezed states of light are used to reduce the quantum noise. We present a new electronic circuit design reducing the electronic noise of the photodetection circuit in the audio band. In the application of this circuit at the gravitational-wave detector GEO 600 the shot-noise to electronic noise ratio was permanently improved by a factor of more than 4 above 1 kHz, while the dynamic range was improved by a factor of 7. The noise equivalent photocurrent of the implemented photodetector and circuit is about 5μA/Hz above 1 kHz with a maximum detectable photocurrent of 20 mA. With the new circuit, the observed squeezing level in GEO 600 increased by 0.2 dB. The new circuit also creates headroom for higher laser power and more squeezing to be observed in the future in GEO 600 and is applicable to other optics experiments.

  11. 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.

  12. Instrumentation for high accuracy noise characterisation of front-end devices in detector applications

    Energy Technology Data Exchange (ETDEWEB)

    Re, V. [Pavia Univ. (Italy). Ist. di Elettronica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy); Svelto, F. [Pavia Univ. (Italy). Ist. di Elettronica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy)

    1995-11-01

    The paper describes the instrumentation that was developed for the noise characterisation of field-effect and bipolar transistors. Very accurate measurements of the series noise spectral density in the frequency range 100mHz-100MHz and of the equivalent noise charge at processing times ranging from 10ns to 10{mu}s are made possible. A review of results on various device types shows how these data are used in view of applications to a broad range of experimental conditions in elementary particle and nuclear physics. (orig.).

  13. Integrated covariance estimation using high-frequency data in the presence of noise

    DEFF Research Database (Denmark)

    Voev, Valeri; Lunde, Asger

    2007-01-01

    . When noise is present, however, we find that this estimator is biased, and show how the bias can be corrected for. Ultimately, we propose a subsampling version of the bias-corrected estimator which improves its efficiency. Empirically, we find that the usual assumption of a martingale price process...... plus an independently and identically distributed (i.i.d.) noise does not describe the dynamics of the observed price process across stocks, which confirms the practical relevance of our general noise specification and the estimation techniques we propose.Finally, a simulation experiment is carried out...

  14. Turbulent-PSO-Based Fuzzy Image Filter With No-Reference Measures for High-Density Impulse Noise.

    Science.gov (United States)

    Chou, Hsien-Hsin; Hsu, Ling-Yuan; Hu, Hwai-Tsu

    2013-02-01

    Digital images are often corrupted by impulsive noise during data acquisition, transmission, and processing. This paper presents a turbulent particle swarm optimization (PSO) (TPSO)-based fuzzy filtering (or TPFF for short) approach to remove impulse noise from highly corrupted images. The proposed fuzzy filter contains a parallel fuzzy inference mechanism, a fuzzy mean process, and a fuzzy composition process. To a certain extent, the TPFF is an improved and online version of those genetic-based algorithms which had attracted a number of works during the past years. As the PSO is renowned for its ability of achieving success rate and solution quality, the superiority of the TPFF is almost for sure. In particular, by using a no-reference Q metric, the TPSO learning is sufficient to optimize the parameters necessitated by the TPFF. Therefore, the proposed fuzzy filter can cope with practical situations where the assumption of the existence of the "ground-truth" reference does not hold. The experimental results confirm that the TPFF attains an excellent quality of restored images in terms of peak signal-to-noise ratio, mean square error, and mean absolute error even when the noise rate is above 0.5 and without the aid of noise-free images.

  15. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock.

    Science.gov (United States)

    François, B; Calosso, C E; Danet, J M; Boudot, R

    2014-09-01

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be -42, -100, -117 dB rad(2)/Hz and -129 dB rad(2)/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10(-14) at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

  16. A 6 GHz high power and low phase noise VCO using an InGaP/GaAs HBT

    Institute of Scientific and Technical Information of China (English)

    王显泰; 申华军; 金智; 陈延湖; 刘新宇

    2009-01-01

    A 6 GHz voltage controlled oscillator (VCO) optimized for power and noise performance was designed and characterized. This VCO was designed with the negative-resistance (Neg-R) method, utilizing an InGaP/GaAs hetero-junction bipolar transistor in the negative-resistance block. A proper output matching network and a high Q stripe line resonator were used to enhance output power and depress phase noise. Measured central frequency of the VCO was 6.008 GHz. The tuning range was more than 200 MHz. At the central frequency, an output power of 9.8 dBm and phase noise of -122.33 dBc/Hz at 1 MHz offset were achieved, the calculated RF to DC efficiency was about 14%, and the figure of merit was -179.2 dBc/Hz.

  17. High accuracy measurement of low-frequency noise in front-end p-channel FETs

    Energy Technology Data Exchange (ETDEWEB)

    Re, V. [Pavia Univ. (Italy). Ist. di Elettronica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy); Svelto, F. [Pavia Univ. (Italy). Ist. di Elettronica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy)

    1995-11-01

    The paper describes the instrumentation that was developed to allow series noise spectral analysis on field effect transistors. Analog interfaces between the device under test and commercial available analysers, working in the frequency range 100mHz-100kHz, have been designed and realised. The intrinsic noise contribution of the interface is estimated to be 1nV/{radical}(Hz) at 100mHz and 50pV/{radical}(Hz) beyond 1kHz. The basic idea is to amplify the noise of the device under test through a capacitive feedback loop, which is theoretically noiseless. The paper is focused on the design and the performances of the interface for the noise characterisation of p-channel FETs. (orig.).

  18. A High Performance Approach to Local Active Noise Reduction in Noisy Cabins Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft cabin is noisy and uncomfortable. Sometimes, the noise level can exceed 80 dBA. There are 2 challenges to meet the above needs. One is to generate an...

  19. Unstructured, High-Order Scheme Module with Low Dissipation Flux Difference Splitting for Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorough understanding of aircraft airframe and engine noise mechanisms and the subsequent acoustic propagation to the farfield is necessary to develop and evaluate...

  20. Non-Linear Noise Contributions in Highly Dispersive Optical Transmission Systems

    Science.gov (United States)

    Matera, Francesco

    2016-01-01

    This article reports an analytical investigation, confirmed by numerical simulations, about the non-linear noise contribution in single-channel systems adopting generic modulation-detection formats in long links with both managed and unmanaged dispersion compensation and its impact in system performance. This noise contribution is expressed in terms of a pulse non-linear interaction length and permits a simple calculation of the Q-factor. Results point out the dependence of this non-linear noise on the number of amplifiers spans, N, according to the adopted chromatic dispersion compensation scheme, the modulation-detection format, and the signal baud rate. It is also shown how the effects of polarization multiplexing can be taken into account and how this single-channel non-linear noise contribution can be used in a wavelength-division multiplexing (WDM) environment.

  1. High Sensitivity Pulsed Laser Vibrometer for Aircraft Interior Noise Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an innovative pulsed laser vibrometer technology for the monitoring of interior noise inside an aircraft. The optical speckle-tolerant nature of the...

  2. Characteristics of atmospheric carbon monoxide at a high-mountain background station in East Asia

    Science.gov (United States)

    Ou-Yang, Chang-Feng; Lin, Neng-Huei; Lin, Chia-Ching; Wang, Sheng-Hsiang; Sheu, Guey-Rong; Lee, Chung-Te; Schnell, Russell C.; Lang, Patricia M.; Kawasato, Taro; Wang, Jia-Lin

    2014-06-01

    Atmospheric CO were monitored at the Lulin Atmospheric Background Station (LABS) with an elevation of 2862 m AMSL from April 2006 to April 2011 by the in-situ non-dispersive infrared (NDIR) spectrometer and weekly flask sample collections via collaboration with NOAA/ESRL/GMD. In general very coherent results were observed between the two datasets, despite a slight difference between the two. A distinct seasonal pattern of CO was noticed at the LABS with a springtime maximum and a summertime minimum, which was predominately shaped by the long-range transport of biomass burning air masses from Southeast Asia and oceanic influences from the Pacific, respectively. Diurnal cycles were also observed at the LABS, with a maximum in late afternoon and a minimum in early morning. The daytime CO maximum was most likely caused by the up-slope transport of lower elevation air. After filtering out the possibly polluted data points from the entire dataset with a mathematic procedure, the mean background CO level at the LABS was assessed as 129.3 ± 46.6 ppb, compared to 149.0 ± 72.2 ppb prior to the filtering. The cluster analysis of the backward trajectories revealed six possible source regions, which shows that air masses originating from the Westerly Wind Zone were dominated in spring and winter resulting in higher CO concentrations. As a contrast, the oceanic influences from the Pacific were found mostly in summer, contributing a lower seasonal CO concentration throughout a year.

  3. The influences of low frequency noise on mental performance

    Directory of Open Access Journals (Sweden)

    J. Hatami

    2008-01-01

    Full Text Available AbstractBackground and Purpose: Although the evolution of industrial systems toward digital technologies decreased the exposure to high levels of noise, it has created some problems encountered with low level and provoking noise (low frequency noise. In the present work, the mental performance of students exposed to low frequency and reference noises at low and high levels (45 & 65 dB were studied. Additionally, other factors such as annoyance, sensitivity to low frequency noise and hearing status of participants were considered.Materials and Methods: After generating low frequency and reference noises required for the study, a pilot study was conducted. Then, 54 students participated in the main study after preliminary tests. Their mental performances were evaluated with standard psychological tests while they were exposed to low frequency and reference noises at 45 and 65 dBA.Results: The results showed that noise annoyance and low frequency noise sensitivity do not have a significant correlation with age and sex. The results also revealed that, low frequency noise at 65 dB can decrease concentration (P=0.003 and increase response time (P=0.039 of performance in comparison with low frequency noise at 45 dB. On the other hand, reference noise at 65 dB can increase speed (P<0.001 of performance in comparison with reference noise at 45 dB.Conclusion: Low frequency noise can reduce the mental performance and increase its response time.Key words: Low Frequency Noise, Reference Noise, Noise Annoyance, Mental PerformanceJ Mazand Univ Med Sci 2008; 18(63: 55-65(Persian

  4. Spectral characteristics of high-latitude raw 40 MHz cosmic noise signals

    Science.gov (United States)

    Hall, Chris M.

    2016-08-01

    Cosmic noise at 40 MHz is measured at Ny-Ålesund (79° N, 12° E) using a relative ionospheric opacity meter ("riometer"). A riometer is normally used to determine the degree to which cosmic noise is absorbed by the intervening ionosphere, giving an indication of ionisation of the atmosphere at altitudes lower than generally monitored by other instruments. The usual course is to determine a "quiet-day" variation, this representing the galactic noise signal itself in the absence of absorption; the current signal is then subtracted from this to arrive at absorption expressed in decibels (dB). By a variety of means and assumptions, it is thereafter possible to estimate electron density profiles in the very lowest reaches of the ionosphere. Here however, the entire signal, i.e. including the cosmic noise itself, will be examined and spectral characteristics identified. It will be seen that distinct spectral subranges are evident which can, in turn, be identified with non-Gaussian processes characterised by generalised Hurst exponents, α. Considering all periods greater than 1 h, α ≈ 24, an indication of fractional Brownian motion, whereas for periods greater than 1 day α ≈ 0.9 - approximately pink noise and just in the domain of fractional Gaussian noise. The results are compared with other physical processes, suggesting that absorption of cosmic noise is characterised by a generalised Hurst exponent ≈ 1.24 and thus non-persistent fractional Brownian motion, whereas generation of cosmic noise is characterised by a generalised Hurst exponent ≈ 1. The technique unfortunately did not result in clear physical understanding of the ionospheric phenomena, and thus, in this respect, the application was not successful; the analysis could, however, be used as a tool for instrument validation.

  5. Numerical prediction of flow induced noise in free jets of high Mach numbers

    OpenAIRE

    Schönrock, Olaf

    2009-01-01

    A direct aeroacoustic simulation methodology is developed on the basis of the numerical schemes implemented in the commercial tool ANSYS CFX. The focus lies upon the efficient and direct numerical prediction of the flow-induced noise generated by natural gas and pneumatic applications. The respective compressed gas related components are characterized by tiny supersonic gas jets, strong noise emissions, poor accessibility by measurement techniques and excessive simulation costs in particular...

  6. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system

    Science.gov (United States)

    Liu, Jinzhen; Qiao, Xiaoyan; Wang, Mengjun; Zhang, Weibo; Li, Gang; Lin, Ling

    2014-05-01

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  7. Computationally efficient algorithm for high sampling-frequency operation of active noise control

    Science.gov (United States)

    Rout, Nirmal Kumar; Das, Debi Prasad; Panda, Ganapati

    2015-05-01

    In high sampling-frequency operation of active noise control (ANC) system the length of the secondary path estimate and the ANC filter are very long. This increases the computational complexity of the conventional filtered-x least mean square (FXLMS) algorithm. To reduce the computational complexity of long order ANC system using FXLMS algorithm, frequency domain block ANC algorithms have been proposed in past. These full block frequency domain ANC algorithms are associated with some disadvantages such as large block delay, quantization error due to computation of large size transforms and implementation difficulties in existing low-end DSP hardware. To overcome these shortcomings, the partitioned block ANC algorithm is newly proposed where the long length filters in ANC are divided into a number of equal partitions and suitably assembled to perform the FXLMS algorithm in the frequency domain. The complexity of this proposed frequency domain partitioned block FXLMS (FPBFXLMS) algorithm is quite reduced compared to the conventional FXLMS algorithm. It is further reduced by merging one fast Fourier transform (FFT)-inverse fast Fourier transform (IFFT) combination to derive the reduced structure FPBFXLMS (RFPBFXLMS) algorithm. Computational complexity analysis for different orders of filter and partition size are presented. Systematic computer simulations are carried out for both the proposed partitioned block ANC algorithms to show its accuracy compared to the time domain FXLMS algorithm.

  8. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinzhen; Li, Gang; Lin, Ling, E-mail: linling@tju.edu.cn [State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People' s Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin (China); Qiao, Xiaoyan [College of Physics and Electronic Engineering, Shanxi University, Shanxi (China); Wang, Mengjun [School of Information Engineering, Hebei University of Technology, Tianjin (China); Zhang, Weibo [Institute of Acupuncture and Moxibustion China Academy of Chinese Medical Sciences, Beijing (China)

    2014-05-15

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  9. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system.

    Science.gov (United States)

    Liu, Jinzhen; Qiao, Xiaoyan; Wang, Mengjun; Zhang, Weibo; Li, Gang; Lin, Ling

    2014-05-01

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  10. Hybrid CFD/FEM-BEM simulation of cabin aerodynamic noise for vehicles traveling at high speed

    Institute of Scientific and Technical Information of China (English)

    WANG; YiPing; ZHEN; Xin; WU; Jing; GU; ZhengQi; XIAO; ZhenYi; YANG; Xue

    2013-01-01

    Flow passing a vehicle may lead to the increase of the cabin interior noise level through a variety of mechanisms. These mechanisms include vibrations caused by aerodynamic excitations and reradiation from the glass panels, exterior noise trans-mitted and leaked through door seals including gaps and glass edge, and transmission of airborne noise generated by the interaction of flow with body panels. It is of vital importance to predict both the flow fields and the acoustic sources around the ve-hicle to accurately assess the impact of wind induced noise inside the cabin. In the present study, an unstructured segregated finite volume model was used to calculate the flow fields in which a hexahedron grid is used to simplify the vehicle geometry.A large eddy simulation coupled with a wall function model was applied to predict the exterior transient flow fields. The mean flow quantities were thus calculated along the symmetry plane and the vehicle’s side windows. A coupled FEM/BEM method was used to compute the vehicle’s interior noise level. The total contribution of the interior noise level due to the body panels of the vehicle was subsequently analyzed.

  11. Jet-Surface Interaction Noise from High-Aspect Ratio Nozzles: Test Summary

    Science.gov (United States)

    Brown, Clifford; Podboy, Gary

    2017-01-01

    Noise and flow data have been acquired for a 16:1 aspect ratio rectangular nozzle exhausting near a simple surface at the NASA Glenn Research Center as part of an ongoing effort to understand, model, and predict the noise produced by current and future concept aircraft employing a tightly integrated engine airframe designs. The particular concept under consideration in this experiment is a blended-wing-body airframe powered by a series of electric fans exhausting through slot nozzle over an aft deck. The exhaust Mach number and surface length were parametrically varied during the test. Far-field noise data were acquired for all nozzle surface geometries and exhaust flow conditions. Phased-array noise source localization data and in-flow pressure data were also acquired for a subset of the isolated (no surface) and surface configurations; these measurements provide data that have proven useful for modeling the jet-surface interaction noise source and the surface effect on the jet-mixing noise in round jets. A summary of the nozzle surface geometry, flow conditions tested, and data collected are presented.

  12. Large Eddy Simulation of Airfoil Self-Noise at High Reynolds Number

    Science.gov (United States)

    Kocheemoolayil, Joseph; Lele, Sanjiva

    2015-11-01

    The trailing edge noise section (Category 1) of the Benchmark Problems for Airframe Noise Computations (BANC) workshop features five canonical problems. No first-principles based approach free of empiricism and tunable coefficients has successfully predicted trailing edge noise for the five configurations to date. Our simulations predict trailing edge noise accurately for all five configurations. The simulation database is described in detail, highlighting efforts undertaken to validate the results through systematic comparison with dedicated experiments and establish insensitivity to grid resolution, domain size, alleatory uncertainties such as the tripping mechanism used to force transition to turbulence and epistemic uncertainties such as models for unresolved near-wall turbulence. Ongoing efforts to extend the predictive capability to non-canonical configurations featuring flow separation are summarized. A novel, large-span calculation that predicts the flow past a wind turbine airfoil in deep stall with unprecedented accuracy is presented. The simulations predict airfoil noise in the near-stall regime accurately. While the post-stall noise predictions leave room for improvement, significant uncertainties in the experiment might preclude a fair comparison in this regime. We thank Cascade Technologies Inc. for providing access to the CharLES toolkit - a massively-parallel, unstructured large eddy simulation framework.

  13. Characterization of gaseous detectors at the CERN Gamma Irradiation Facility: GEM performance in presence of high background radiation

    CERN Document Server

    AUTHOR|(CDS)2097588

    Muon detection is an efficient tool to recognize interesting physics events over the high background rate expected at the Large Hadron Collider (LHC) at CERN. The muon systems of the LHC experiments are based on gaseous ionization detectors. In view of the High-Luminosity LHC (HL-LHC) upgrade program, the increasing of background radiation could affect the gaseous detector performance, especially decreasing the efficiency and shortening the lifetime through ageing processes. The effects of charge multiplication, materials and gas composition on the ageing of gaseous detectors have been studied for decades, but the future upgrade of LHC requires additional studies on this topic. At the CERN Gamma Irradiation Facility (GIF++), a radioactive source of cesium-137 with an activity of 14 TBq is used to reproduce reasonably well the expected background radiation at HL-LHC. A muon beam has been made available to study detector performance. The characterization of the beam trigger will be discussed in the present w...

  14. Study on spatial resolution of micromegas as a neutron detector under condition of high neutron flux and γ ray background

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-Xin; ZHANG Yi; WANG Ji-Jin; HU Bi-Tao

    2009-01-01

    In this paper Micromegas has been designed to detect neutrons. The simulation of the spatial reso-lution of Micromegas as neutron detector is carried out by GEANT4 toolkit. The neutron track reconstruction method based on the time coincidence technology is employed in the present work. The influence of the flux of incident 14 MeV neutron and high gamma background on the spatial resolution is carefully studied. Our results show that the spatial resolution of the detector is sensitive to the neutron flux, but insensitive to the intensity of γ background if the neutron track reconstruction method proposed by our group is used. The γ insensitivity makes it possible for us to use the Micromegas detector under condition which has high γ-rays background.

  15. Adaptive response of blood lymphocytes of inhabitants residing in high background radiation areas of ramsar- micronuclei, apoptosis and comet assays.

    Science.gov (United States)

    Mohammadi, Shahla; Taghavi-Dehaghani, Mahnaz; Gharaati, Mohammad R; Masoomi, Reza; Ghiassi-Nejad, Mehdi

    2006-11-01

    The hot springs in certain areas of Ramsar contain (226)Ra and (222)Rn. The effects of natural radiation on the inhabitants of these areas and the inhabitant's radiosensitivity or adaptive responses were studied. One group of volunteers from areas with high natural background radiation and another group from areas with normal background radiation were chosen as the case and control group respectively. The frequency of micronuclei, apoptosis, and DNA damage in peripheral blood mononuclear cells were measured following gamma irradiation (4 Gy). The incidence of micronuclei in the case group was significantly lower than that in the control group while their frequency of apoptosis was higher (P sites, the individuals in the case group are more sensitive and susceptible to DNA damage. The results of micronuclei, apoptosis and repair studies suggest that an adaptive response might be induced in people residing in areas with high background radiation.

  16. Acceptable noise level

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  17. Hawkes process model with a time-dependent background rate and its application to high-frequency financial data

    Science.gov (United States)

    Omi, Takahiro; Hirata, Yoshito; Aihara, Kazuyuki

    2017-07-01

    A Hawkes process model with a time-varying background rate is developed for analyzing the high-frequency financial data. In our model, the logarithm of the background rate is modeled by a linear model with a relatively large number of variable-width basis functions, and the parameters are estimated by a Bayesian method. Our model can capture not only the slow time variation, such as in the intraday seasonality, but also the rapid one, which follows a macroeconomic news announcement. By analyzing the tick data of the Nikkei 225 mini, we find that (i) our model is better fitted to the data than the Hawkes models with a constant background rate or a slowly varying background rate, which have been commonly used in the field of quantitative finance; (ii) the improvement in the goodness-of-fit to the data by our model is significant especially for sessions where considerable fluctuation of the background rate is present; and (iii) our model is statistically consistent with the data. The branching ratio, which quantifies the level of the endogeneity of markets, estimated by our model is 0.41, suggesting the relative importance of exogenous factors in the market dynamics. We also demonstrate that it is critically important to appropriately model the time-dependent background rate for the branching ratio estimation.

  18. Probing the High-Redshift Universe Using Fluctuations in the Cosmic Microwave and Infrared Backgrounds

    Science.gov (United States)

    Smidt, Joseph Michael

    Background (CIB) continues to be one of the best probes of physics at the early stages of the universe. If the CMB were a purely Gaussian field, all statistical information would be contained in the power spectrum or two-point correlation function. However, non-Gaussianities ensure that new physics may be extracted from higher n-point correlation functions including the bispectrum and trispectrum of the CMB. In this thesis discuss new estimators we have formulated to probe primordial non-Gaussianity in the bispectrum and trispectrum of CMB data and the constraints we have made using WMAP data while discussing implications for inflationary models. I discuss how these same methods may be used to probe CMB Lensing. Finally, I discuss how upcoming measurements of near and far-infrared CIB fluctuations may be used to constrain the redshift of reionization and clustering of various populations of galaxies. Some preliminary results involving CANDELS, Spitzer SDWFS, CIBER and Herschel datasets is presented.

  19. ATLAS MDT chamber behaviour after neutron irradiation and in a high rate background

    Energy Technology Data Exchange (ETDEWEB)

    Branchini, Paolo; Di Luise, Silvestro; Graziani, Enrico [Dipartimento di Fisica, Universita di Rome Tre and INFN Sezione di Roma Tre, Rome (Italy); Mazzotta, Concetta; Meoni, Evelin; Morello, Gianfranco [Dipartimento di Fisica, Universita della Calabria and INFN Gruppo Collegato di Cosenza, Cosenza (Italy); Passeri, Antonio; Petrucci, Fabrizio [Dipartimento di Fisica, Universita di Rome Tre and INFN Sezione di Roma Tre, Rome (Italy); Policicchio, Antonio [Dipartimento di Fisica, Universita della Calabria and INFN Gruppo Collegato di Cosenza, Cosenza (Italy)], E-mail: antonio.policicchio@cern.ch; Salvatore, Daniela; Schioppa, Marco [Dipartimento di Fisica, Universita della Calabria and INFN Gruppo Collegato di Cosenza, Cosenza (Italy)

    2007-10-21

    Many of the physics processes of interest at the Large Hadron Collider (LHC) will involve muon production in the final state. The Monitored Drift Tube (MDT) chambers, the precision tracking elements of the ATLAS muon spectrometer, are the main tools for the muon identification and measurement. They will operate in the harsh LHC background environment, mainly due to low energy photons and neutrons which will dominate the counting rate in most areas of the spectrometer, where an overall maximum counting rate of 500Hz/cm{sup 2} is expected. The upgrade to Super-LHC will involve fluxes ten times higher. To study the behaviour of MDT chambers under massive neutron irradiation at the level of Super-LHC, a test was performed at the 'Tapiro' Neutron Facility of the ENEA 'La Casaccia' Research Center.

  20. Noise levels of dental equipment used in dental college of Damascus University

    OpenAIRE

    Mhd. Loutify Qsaibati; Ousama Ibrahim

    2014-01-01

    Background: In dental practical classes, the acoustic environment is characterized by high noise levels in relation to other teaching areas. The aims of this study were to measure noise levels produced during the different dental learning clinics, by equipments used in dental learning areas under different working conditions and by used and brand new handpieces under different working conditions. Materials and Methods: The noise levels were measured by using a noise level meter with a mic...

  1. A low noise, high thermal stability, 0.1 K test facility for the Planck HFI bolometers

    OpenAIRE

    2002-01-01

    We are developing a facility which will be used to characterize the bolometric detectors for Planck, an ESA mission to investigate the Cosmic Microwave Background. The bolometers operate at 0.1 K, employing neutron-transmutation doped (NTD) Ge thermistors with resistances of several megohms to achieve NEPs~1×10^(–17) W Hz^(–1/2). Characterization of the intrinsic noise of the bolometers at frequencies as low as 0.010 Hz dictates a test apparatus thermal stability of 40 nK Hz^(–1/2) to that fr...

  2. High-Resolution Dual-Comb Spectroscopy with Ultra-Low Noise Frequency Combs

    Science.gov (United States)

    Hänsel, Wolfgang; Giunta, Michele; Beha, Katja; Perry, Adam J.; Holzwarth, R.

    2017-06-01

    Dual-comb spectroscopy is a powerful tool for fast broad-band spectroscopy due to the parallel interrogation of thousands of spectral lines. Here we report on the spectroscopic analysis of acetylene vapor in a pressurized gas cell using two ultra-low noise frequency combs with a repetition rate around 250 MHz. Optical referencing to a high-finesse cavity yields a sub-Hertz stability of all individual comb lines (including the virtual comb lines between 0 Hz and the carrier) and permits one to pick a small difference of repetition rate for the two frequency combs on the order of 300 Hz, thus representing an optical spectrum of 100 THz (˜3300 \\wn) within half the free spectral range (125 MHz). The transmission signal is derived straight from a photodetector and recorded with a high-resolution spectrum analyzer or digitized with a computer-controlled AD converter. The figure to the right shows a schematic of the experimental setup which is all fiber-coupled with polarization-maintaining fiber except for the spectroscopic cell. The graph on the lower right reveals a portion of the recorded radio-frequency spectrum which has been scaled to the optical domain. The location of the measured absorption coincides well with data taken from the HITRAN data base. Due to the intrinsic linewidth of all contributing comb lines, each sampling point in the transmission graph corresponds to the probing at an optical frequency with sub-Hertz resolution. This resolution is maintained in coherent wavelength conversion processes such as difference-frequency generation (DFG), sum-frequency generation (SFG) or non-linear broadening (self-phase modulation), and is therefore easily transferred to a wide spectral range from the mid infrared up to the visible spectrum.

  3. Absorption of High Energy $\\gamma$ Rays by Interactions With Starlight Photons in Extragalactic Space at High Redshifts and the High Energy $\\gamma$-Ray Background

    CERN Document Server

    Salamon, M H

    1998-01-01

    We calculate the absorption of 10-500 GeV gamma-rays at high redshifts. This calculation requires the determination of the high-redshift evolution of the intergalactic starlight photon field, including its IR-UV spectral energy distribution. To estimate this evolution, we have followed a recent analysis of Fall, Charlot and Pei which gives results consistent with recent data. We give our results for the gamma-ray opacity as a function of redshift out to a redshift of 3. We also give predicted gamma-ray spectra for selected blazars and give an extragalactic unresolved blazar background spectrum up to 500 GeV. Our results indicate that this background should steepen significantly above 20 GeV owing to intergalactic absorption. Future observations of this steepening would provide a test for the blazar background origin hypothesis. We have used our results to discuss upper limits on the redshifts of gamma-ray bursts. We note that the 17 Feb. 1994 burst observed by EGRET must have originated at a redshift less tha...

  4. Constraining Dark Matter and Ultra-High Energy Cosmic Ray Sources with Fermi-LAT Diffuse Gamma Ray Background

    CERN Document Server

    Kalashev, Oleg

    2016-01-01

    We use the recent measurement of the isotropic $\\gamma$-ray background (IGRB) by Fermi LAT and analysis of the contribution of unresolved point $\\gamma$-ray sources to IGRB to build constraints on the models of ultra-high cosmic rays (UHECR) origin. We also calculate the minimal expected diffuse $\\gamma$-ray flux produced by UHECR interactions with an interstellar photon background. Finally, for the subclass of dark matter (DM) models with decaying weakly interacting massive particles (WIMP), we build constraints on the particle decay time using minimal expected contributions to the IGRB from unresolved point $\\gamma$-ray sources and UHECR.

  5. Lip-reading aids word recognition most in moderate noise: a Bayesian explanation using high-dimensional feature space.

    Directory of Open Access Journals (Sweden)

    Wei Ji Ma

    Full Text Available Watching a speaker's facial movements can dramatically enhance our ability to comprehend words, especially in noisy environments. From a general doctrine of combining information from different sensory modalities (the principle of inverse effectiveness, one would expect that the visual signals would be most effective at the highest levels of auditory noise. In contrast, we find, in accord with a recent paper, that visual information improves performance more at intermediate levels of auditory noise than at the highest levels, and we show that a novel visual stimulus containing only temporal information does the same. We present a Bayesian model of optimal cue integration that can explain these conflicts. In this model, words are regarded as points in a multidimensional space and word recognition is a probabilistic inference process. When the dimensionality of the feature space is low, the Bayesian model predicts inverse effectiveness; when the dimensionality is high, the enhancement is maximal at intermediate auditory noise levels. When the auditory and visual stimuli differ slightly in high noise, the model makes a counterintuitive prediction: as sound quality increases, the proportion of reported words corresponding to the visual stimulus should first increase and then decrease. We confirm this prediction in a behavioral experiment. We conclude that auditory-visual speech perception obeys the same notion of optimality previously observed only for simple multisensory stimuli.

  6. Using the Crab Nebula as a high precision calibrator for Cosmic Microwave Background polarimeters

    CERN Document Server

    Kaufman, Jonathan; Leon, David

    2016-01-01

    The polarization of the Cosmic Microwave Background (CMB) provides a plethora of information about the early universe. Most notably, gravitational waves from the Inflationary epoch (the leading explanation of the origin of the universe) create a unique CMB polarization $B$-mode signal. An unambiguous detection of the inflationary $B$-mode signal would be a window into the physics of the universe as it was $10^{-36}$ seconds after the Big Bang, at energy scales many orders of magnitude larger than what the LHC can produce. However, there are several instrumental and astrophysical sources that can obfuscate the inflationary $B$-mode signal. One of the most difficult parameters to calibrate for CMB telescopes is the absolute orientation of the antenna's polarization sensitive axis. A miscalibration of the polarization orientation rotates the much brighter $E$-mode signal, producing a false $B$-mode signal. The current best uncertainty on polarization orientation in the CMB community is $0.5^\\circ$, set from extr...

  7. Extracting Near-Field Structures Related to Noise Production in High Speed Jet

    Science.gov (United States)

    Kan, Pinqing; Lewalle, Jacques; Syracuse University Team

    2015-11-01

    Jet noise research started with Lighthill's seminal work on aerodynamic sound in 1952. The current consensus is that jet noise has two main kinds of sources, the large turbulent structures and the fine-scale turbulence. Coherent structures and the noise they produce are the focus of this paper because they offer better odds for control and they are associated with the most energetic part of the acoustic spectrum. We develop an algorithm using cross-correlation, continuous wavelet and pattern recognition techniques to search for near-field (NF) structures associated with far-field (FF) acoustic noise at aft angles. An experimental data is analyzed which measured a cold circular jet of Mach 0.6 (Low et al. 2013). The events identified are short wave packets in the time-frequency domain, distorted by ambient perturbations. The statistics of the event properties, including intermittency, frequency and magnitude are consistent with observations from other researchers. We investigate the localization and time sequencing of the events and use ensemble average to bring out the distinct structures associated to noise production. The filtered signals including / excluding the events are compared and the results are further tested using synthetic and randomized signals. This work has been funded by Spectral Energies LLC through an Air Force Research Lab SBIR, an AFOSR Grant and Syracuse University.

  8. High Resolution Flicker-Noise-Free Frequency Measurements of Weak Microwave Signals

    CERN Document Server

    Creedon, Daniel L; Ivanov, Eugene N; Hartnett, John G

    2011-01-01

    Amplification is usually necessary when measuring the frequency instability of microwave signals. In this work, we develop a flicker noise free frequency measurement system based on a common or shared amplifier. First, we show that correlated flicker phase noise can be cancelled in such a system. Then we compare the new system with the conventional by simultaneously measuring the beat frequency from two cryogenic sapphire oscillators with parts in 10^15 fractional frequency instability. We determine for low power, below -80 dBm, the measurements were not limited by correlated noise processes but by thermal noise of the readout amplifier. In this regime, we show that the new readout system performs as expected and at the same level as the standard system but with only half the number of amplifiers. We also show that, using a standard readout system, the next generation of cryogenic sapphire oscillators could be flicker phase noise limited when instability reaches parts in 10^16 or better

  9. Nonlinear modeling of low-to-high-frequency noise up-conversion in microwave electron devices

    Science.gov (United States)

    Filicori, Fabio; Traverso, Pier A.; Florian, Corrado

    2003-05-01

    Measurement-based, circuit-oriented non-linear noise modeling of microwave electron devices is still an open field of research, since existing approaches are not always suitable for the accurate prediction of low-frequency noise up-conversion to RF, which represents an essential information for the non-linear circuit analyses performed in the CAD of low phase-noise oscillators. In this paper a technology-independent, empirical approach to the modeling of noise contributions at the ports of electron devices, operating under strongly non-linear conditions, is proposed. Details concerning the analytical formulation of the model, which is derived by considering randomly time-varying perturbations in the basic equations of an otherwise conventional charge-controlled non-linear model, are presented, along with a discussion about the measurement techniques devoted to its experimental characterization. An example of application of the proposed Charge-Controlled Non-linear Noise (CCNN) model is considered in the case of a HBT transistor. Techniques devoted to the implementation of the obtained model in the framework of commercial CAD tools for circuit analysis and design are provided as well.

  10. Animation of natural scene by virtual eye-movements evokes high precision and low noise in V1 neurons.

    Science.gov (United States)

    Baudot, Pierre; Levy, Manuel; Marre, Olivier; Monier, Cyril; Pananceau, Marc; Frégnac, Yves

    2013-01-01

    Synaptic noise is thought to be a limiting factor for computational efficiency in the brain. In visual cortex (V1), ongoing activity is present in vivo, and spiking responses to simple stimuli are highly unreliable across trials. Stimulus statistics used to plot receptive fields, however, are quite different from those experienced during natural visuomotor exploration. We recorded V1 neurons intracellularly in the anaesthetized and paralyzed cat and compared their spiking and synaptic responses to full field natural images animated by simulated eye-movements to those evoked by simpler (grating) or higher dimensionality statistics (dense noise). In most cells, natural scene animation was the only condition where high temporal precision (in the 10-20 ms range) was maintained during sparse and reliable activity. At the subthreshold level, irregular but highly reproducible membrane potential dynamics were observed, even during long (several 100 ms) "spike-less" periods. We showed that both the spatial structure of natural scenes and the temporal dynamics of eye-movements increase the signal-to-noise ratio by a non-linear amplification of the signal combined with a reduction of the subthreshold contextual noise. These data support the view that the sparsening and the time precision of the neural code in V1 may depend primarily on three factors: (1) broadband input spectrum: the bandwidth must be rich enough for recruiting optimally the diversity of spatial and time constants during recurrent processing; (2) tight temporal interplay of excitation and inhibition: conductance measurements demonstrate that natural scene statistics narrow selectively the duration of the spiking opportunity window during which the balance between excitation and inhibition changes transiently and reversibly; (3) signal energy in the lower frequency band: a minimal level of power is needed below 10 Hz to reach consistently the spiking threshold, a situation rarely reached with visual dense

  11. Animation of natural scene by virtual eye-movements evokes high precision and low noise in V1 neurons

    Directory of Open Access Journals (Sweden)

    Pierre eBaudot

    2013-12-01

    Full Text Available Synaptic Noise is thought to be a limiting factor for computational efficiency in the Brain. In visual cortex (V1, ongoing activity is present in vivo, and spiking responses to simple stimuli are highly unreliable across trials. Stimulus statistics used to plot receptive fields, however, are quite different from those experienced during natural visuomotor exploration. We recorded V1 neurons intracellularly in the anaesthetized and paralyzed cat and compared their spiking and synaptic responses to full field natural images animated by simulated eye-movements to those evoked by simpler (grating or higher dimensionality statistics (dense noise. In most cells, natural scene animation was the only condition where high temporal precision (in the 10-20 ms range was maintained during sparse and reliable activity. At the subthreshold level, irregular but highly reproducible membrane potential dynamics were observed, even during long (several 100 ms spike-less periods. We showed that both the spatial structure of natural scenes and the temporal dynamics of eye-movements increase the signal-to-noise ratio by a non linear amplification of the signal combined with a reduction of the subthreshold contextual noise. These data support the view that the sparsening and the time precision of the neural code in V1 may depend primarily on three factors: 1 broadband input spectrum: the bandwidth must be rich enough for recruiting optimally the diversity of spatial and time constants during recurrent processing; 2 tight temporal interplay of excitation and inhibition: conductance measurements demonstrate that natural scene statistics narrow selectively the duration of the spiking opportunity window during which the balance between excitation and inhibition changes transiently and reversibly; 3 signal energy in the lower frequency band: a minimal level of power is needed below 10 Hz to reach consistently the spiking threshold, a situation rarely reached with visual

  12. The prediction of noise and installation effects of high-subsonic dual-stream jets in flight

    Science.gov (United States)

    Saxena, Swati

    Both military and civil aircraft in service generate high levels of noise. One of the major contributors to this noise generated from the aircraft is the jet engine exhaust. This makes the study of jet noise and methods to reduce jet noise an active research area with the aim of designing quieter military and commercial aircraft. The current stringent aircraft noise regulations imposed by the Federal Aviation Administration (FAA) and other international agencies, have further raised the need to perform accurate jet noise calculations for more reliable estimation of the jet noise sources. The main aim of the present research is to perform jet noise simulations of single and dual-stream jets with engineering accuracy and assess forward flight effects on the jet noise. Installation effects such as caused by the pylon are also studied using a simplified pylon nozzle configuration. Due to advances in computational power, it has become possible to perform turbulent flow simulations of high speed jets, which leads to more accurate noise predictions. In the present research, a hybrid unsteady RANS-LES parallel multi-block structured grid solver called EAGLEJet is written to perform the nozzle flow calculations. The far-field noise calculation is performed using solutions to the Ffowcs Williams and Hawkings equation. The present calculations use meshes with 5 to 11 million grid points and require about three weeks of computing time with about 100 processors. A baseline single stream convergent nozzle and a dual-stream coaxial convergent nozzle are used for the flow and noise analysis. Calculations for the convergent nozzle are performed at a high subsonic jet Mach number of Mj = 0.9, which is similar to the operating conditions for commercial aircraft engines. A parallel flow gives the flight effect, which is simulated with a co-flow Mach number, Mcf varying from 0.0 to 0.28. The grid resolution effects, statistical properties of the turbulence and the heated jet effects

  13. Nighttime aircraft noise impairs endothelial function and increases blood pressure in patients with or at high risk for coronary artery disease.

    Science.gov (United States)

    Schmidt, Frank; Kolle, Kristoffer; Kreuder, Katharina; Schnorbus, Boris; Wild, Philip; Hechtner, Marlene; Binder, Harald; Gori, Tommaso; Münzel, Thomas

    2015-01-01

    Epidemiological studies suggest the existence of a relationship between aircraft noise exposure and increased risk for myocardial infarction and stroke. Patients with established coronary artery disease and endothelial dysfunction are known to have more future cardiovascular events. We therefore tested the effects of nocturnal aircraft noise on endothelial function in patients with or at high risk for coronary artery disease. 60 Patients (50p 1-3 vessels disease; 10p with a high Framingham Score of 23%) were exposed in random and blinded order to aircraft noise and no noise conditions. Noise was simulated in the patients' bedroom and consisted of 60 events during one night. Polygraphy was recorded during study nights, endothelial function (flow-mediated dilation of the brachial artery), questionnaires and blood sampling were performed on the morning after each study night. The mean sound pressure levels L eq(3) measured were 46.9 ± 2.0 dB(A) in the Noise 60 nights and 39.2 ± 3.1 dB(A) in the control nights. Subjective sleep quality was markedly reduced by noise from 5.8 ± 2.0 to 3.7 ± 2.2 (p aircraft noise markedly impairs endothelial function in patients with or at risk for cardiovascular disease. These vascular effects appear to be independent from annoyance and attitude towards noise and may explain in part the cardiovascular side effects of nighttime aircraft noise.

  14. Using the Crab Nebula as a high precision calibrator for cosmic microwave background polarimeters

    Science.gov (United States)

    Kaufman, Jonathan; Leon, David; Keating, Brian

    2016-03-01

    The polarization of the cosmic microwave background (CMB) provides a plethora of information about the early universe. Most notably, gravitational waves from the Inflationary epoch (the leading explanation of the origin of the universe) create a unique CMB polarization B-mode signal. An unambiguous detection of the Inflationary B-mode signal would be a window into the physics of the universe as it was 10-36s after the Big Bang, at energy scales many orders of magnitude larger than what the LHC can produce. However, there are several instrumental and astrophysical sources that can obfuscate the Inflationary B-mode signal. One of the most difficult parameters to calibrate for CMB telescopes is the absolute orientation of the antenna’s polarization sensitive axis. A miscalibration of the polarization orientation rotates the much brighter E-mode signal, producing a false B-mode signal. The current best uncertainty on polarization orientation in the CMB community is 0.5∘, set from extrapolating IRAM measurements of the Crab Nebula supernova remnant at 90 GHz to 150 GHz, where the CMB signals peak. This accuracy is not sufficient to convincingly detect B-modes predicted by currently allowable models of Inflation. We suggest to precisely measure the Crab Nebula’s polarization, which can be calibrated absolutely to 0.1∘ from measurements of the polarized emission of Mars, and use these data to calibrate current and upcoming CMB experiments. In addition to Inflationary B-modes, more precise calibration will allow us to better constrain the sum of the neutrino masses and set limits on exotic physics such as parity violation through cosmic polarization rotation.

  15. Double-pass ytterbium-doped fiber amplifier with high gain coefficient and low noise figure

    Institute of Scientific and Technical Information of China (English)

    Anting Wang(王安廷); Meishu Xing(邢美术); Guanghui Chen(陈光辉); Wenkui Yang(杨文奎); Hai Ming(明海); Jianping Xie(谢建平); Yunxia Wu(吴云霞)

    2003-01-01

    We have proposed and demonstrated a double-pass ytterbium-doped fiber amplifier using an optical circulator and a fiber Bragg grating as reflector. When the signal has passed through the ytterbium-doped fiber once, it reflects off a 0.2-nm passive fiber Bragg grating filter. This reduces amplified spontaneous emission (ASE) noise from the first pass. The input signal light is amplified both forward and backward through ytterbium-doped fiber. With this double-pass configuration, 1053.15-nm unsaturated signal gain of 28 dB, gain coefficient of 1.1 dB/mW, and noise figure of less than 4 dB are achieved at 977-nm pump power of 68 mW. It is also found that this double-pass configure provides enhancing gain coefficient and improving noise figure by comparison with single-pass configuration.

  16. A Modified Decision Based Mean Median Algorithm for Removal of High Density Salt and Pepper Noise

    Directory of Open Access Journals (Sweden)

    Jitender Kumar

    2014-03-01

    Full Text Available This paper presents a modified decision based mean median filter for removal of salt and pepper noise in gray scale images. This is a computationally efficient filtering technique. It is implemented in two steps: In the first step, noisy pixels are identified and in the second step, the proposed algorithm is applied only on noisy pixels. The noise free pixels are not modified, which helps in retaining the image features. Experimental results show that the proposed algorithm performs better than various recent denoising methods in terms of PSNR, IEF and MSE.

  17. RADIU-226 CONTENT IN SOIL OF THE HIGH NATURAL BACKGROUND RADIATION AREA OF RAMSAR (IRAN

    Directory of Open Access Journals (Sweden)

    B.Khademi

    1978-11-01

    Full Text Available The existence of a high natural radiation area in the northern part of Iran (Ramsar is proved. Ra 226 in soil is measured. The results are: minimum 23.5 pCi/g and maximum 999 pCi/g soil. Environmental radioactivity is from 0.1 to 5 mr/h.

  18. Assessment of Noise Exposure and Noise Annoyance in a Steel Factory

    Directory of Open Access Journals (Sweden)

    Leila Ibrahimi Ghavam Abadi

    2016-09-01

    Full Text Available Background Noise pollution is one of the most important risk factors in industrial settings. This study aimed to assess noise exposure and noise-induced annoyance among workers of a steel factory. Methods This cross-sectional study was conducted on 70 healthy male participants (33 office employees and 37 production line workers in a steel plant. Results The results showed that 24.24% of employees in office areas and 54% of blue-collar workers had high noise annoyance. Also, noise levels in two parts of steel factory and percentage of responds by participants that felt highly annoyed showed a significant relationship (P < 0.05. Feeling of discomfort was a major complaint that was stated by office employees (%59 and blue-collar workers (%38. Conclusions The findings of this investigation have clearly revealed that employees in both parts of steel factory are annoyed by noise. A higher noise level resulted in higher noise annoyance in the exposed workers. The need for implementing noise conservation program was established.

  19. Analytical study of interior noise control by fuselage design techniques on high-speed, propeller-driven aircraft

    Science.gov (United States)

    Revell, J. D.; Balena, F. J.; Koval, L. R.

    1980-01-01

    The acoustical treatment mass penalties required to achieve an interior noise level of 80 dBA for high speed, fuel efficient propfan-powered aircraft are determined. The prediction method used is based on theory developed for the outer shell dynamics, and a modified approach for add-on noise control element performance. The present synthesis of these methods is supported by experimental data. Three different sized aircraft are studied, including a widebody, a narrowbody and a business sized aircraft. Noise control penalties are calculated for each aircraft for two kinds of noise control designs: add-on designs, where the outer wall structure cannot be changed, and advanced designs where the outer wall stiffness level and the materials usage can be altered. For the add-on designs, the mass penalties range from 1.7 to 2.4 percent of the takeoff gross weight (TOGW) of the various aircraft, similar to preliminary estimates. Results for advanced designs show significant reductions of the mass penalties. For the advanced aluminum designs the penalties are 1.5% of TOGW, and for an all composite aircraft the penalties range from 0.74 to 1.4% of TOGW.

  20. Investigating optimal technique in the presence of motor system noise: application to the double layout somersault dismount on high bar.

    Science.gov (United States)

    Hiley, Michael J; Yeadon, Maurice R

    2016-01-01

    Minimising joint torque is often used as an optimisation criterion when investigating human movement. Alternatively, an aspect of performance may be chosen to be maximised when investigating sporting movements. The aim of the study was to optimise the technique in the backward giant circle prior to a double layout somersault dismount from the high bar using various criteria to determine which best characterised the technique adopted by a gymnast. Ten recorded gymnast trials were used to determine bar release parameters and the level of noise in the gymnast's movements. A computer simulation model of a gymnast and bar was used to optimise giant circle technique under three criteria: minimising joint torques, maximising the release window and maximising success in the presence of motor system noise. Local and global optimisations of technique were performed using the three criteria starting from the average technique of the 10 recorded trials. All global optimum solutions diverged from the gymnast's technique. The local optimum for maximising success in the presence of noise had a success rate comparable with the global optimum (98% vs. 100%, respectively). It is concluded that the gymnast's technique is characterised by maximising success despite operating with motor system noise.

  1. Background data for modulus mapping high-performance polyethylene fiber morphologies.

    Science.gov (United States)

    Strawhecker, Kenneth E; Sandoz-Rosado, Emil J; Stockdale, Taylor A; Laird, Eric D

    2017-02-01

    The data included here provides a basis for understanding "Interior morphology of high-performance polyethylene fibers revealed by modulus mapping" (K.E. Strawhecker, E.J. Sandoz-Rosado, T.A. Stockdale, E.D. Laird, 2016) [1], in specific: the multi-frequency (AMFM) atomic force microscopy technique and its application to ultra-high-molecular-weight Polyethylene (UHMWPE) fibers. Furthermore, the data suggests why the Hertzian contact mechanics model can be used within the framework of AMFM theory, simple harmonic oscillator theory, and contact mechanics. The framework is first laid out followed by data showing cantilever dynamics, force-distance spectra in AC mode, and force-distance in contact mode using Polystyrene reference and UHMWPE. Finally topography and frequency shift (stiffness) maps are presented to show the cases where elastic versus plastic deformation may have occurred.

  2. Natural radionuclide and radiological assessment of building materials in high background radiation areas of Ramsar, Iran.

    Science.gov (United States)

    Bavarnegin, Elham; Moghaddam, Masoud Vahabi; Fathabadi, Nasrin

    2013-04-01

    Building materials, collected from different sites in Ramsar, a northern coastal city in Iran, were analyzed for their natural radionuclide contents. The measurements were carried out using a high resolution high purity Germanium (HPGe) gamma-ray spectrometer system. The activity concentration of (226)Ra, (232)Th, and (40)K content varied from below the minimum detection limit up to 86,400 Bqkg(-1), 187 Bqkg(-1), and 1350 Bqkg(-1), respectively. The radiological hazards incurred from the use of these building materials were estimated through various radiation hazard indices. The result of this survey shows that values obtained for some samples are more than the internationally accepted maximum limits and as such, the use of them as a building material pose significant radiation hazard to individuals.

  3. Background data for modulus mapping high-performance polyethylene fiber morphologies

    Directory of Open Access Journals (Sweden)

    Kenneth E. Strawhecker

    2017-02-01

    Full Text Available The data included here provides a basis for understanding “Interior morphology of high-performance polyethylene fibers revealed by modulus mapping” (K.E. Strawhecker, E.J. Sandoz-Rosado, T.A. Stockdale, E.D. Laird, 2016 [1], in specific: the multi-frequency (AMFM atomic force microscopy technique and its application to ultra-high-molecular-weight Polyethylene (UHMWPE fibers. Furthermore, the data suggests why the Hertzian contact mechanics model can be used within the framework of AMFM theory, simple harmonic oscillator theory, and contact mechanics. The framework is first laid out followed by data showing cantilever dynamics, force-distance spectra in AC mode, and force-distance in contact mode using Polystyrene reference and UHMWPE. Finally topography and frequency shift (stiffness maps are presented to show the cases where elastic versus plastic deformation may have occurred.

  4. Masking of earthquake triggering behavior by a high background rate and implications for epidemic-type aftershock sequence inversions

    Science.gov (United States)

    Touati, S.; Naylor, M.; Main, I. G.; Christie, M.

    2011-03-01

    We examine the effects of the spontaneous background event rate and aftershock triggering characteristics on the temporal statistics of seismicity in the epidemic-type aftershock sequence model. Recent work has shown that the earthquake interevent time distribution is generally bimodal: a superposition of a gamma component from triggered aftershocks at short time intervals and an exponential component at longer intervals from spontaneous events and the overlapping of independent aftershock sequences. The relative size of these two components varies between catalogs, so there is no simple, universal scaling; at the extreme of high spontaneous rate, e.g., in large regions, the high probability of temporally overlapping aftershock sequences causes the exponential component to dominate. Here we further explore the effects of both the spontaneous rate and the aftershock triggering parameters. We show that the analytical theory of Saichev and Sornette (2007), although valid under their assumptions, gives the impression of a more "universal" behavior if used outside its stated range of applicability. We also show that within the high-overlap (high-spontaneous rate) regime, a maximum likelihood inversion of the model's temporal parameters is both less accurate and biased; specifically, the background rate is systematically overestimated. This has implications on the suitable range of region sizes for which parameter inversion may be reliable and must therefore be taken into account in any inversion for temporal variations in background rate in time-dependent hazard calculation.

  5. Survey of Gamma Dose and Radon Exhalation Rate from Soil Surface of High Background Natural Radiation Areas in Ramsar, Iran

    Directory of Open Access Journals (Sweden)

    Rouhollah Dehghani

    2013-09-01

    Full Text Available Background: Radon is a radioactive gas and the second leading cause of death due to lung cancer after smoking. Ramsar is known for having the highest levels of natural background radiation on earth. Materials and Methods: In this research study, 50 stations of high radioactivity areas of Ramsar were selected in warm season of the year. Then gamma dose and radon exhalation rate were measured.Results: Results showed that gamma dose and radon exhalation rate were in the range of 51-7100 nSv/hr and 9-15370 mBq/m2s, respectively.Conclusion: Compare to the worldwide average 16 mBq/m2s, estimated average annual effective of Radon exhalation rate in the study area is too high.

  6. KamLAND-PICO dark matter search project Low background test by highly radiopure NaI(Tl)

    Science.gov (United States)

    Fushimi, Kenichi; Ejiri, Hiroyasu; Hazama, Ryuta; Ikeda, Haruo; Imagawa, Kyoshiro; Inoue, Kunio; Kozlov, Alexandre; Orito, Reiko; Shima, Tatsushi; Takemoto, Yasuhiro; Umehara, Saori; Yasuda, Kensuke; KamLAND-PICO Collaboration

    2014-09-01

    KamLAND-PICO aims to search for WIMPs dark matter by means of highly radiopure NaI(Tl) scintillator. The impurities in NaI(Tl) has been successfully reduced by chemical processing of raw NaI(Tl) powder. The intensity of alpha ray was observed and the contamination in 210Pb has been dramatically reduced to about 60 μBq/kg. The present status of low background measurement will be reported.

  7. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2017-01-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  8. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2017-01-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  9. Non-Linear Dynamical Classification of Short Time Series of the Rössler System in High Noise Regimes

    Science.gov (United States)

    Lainscsek, Claudia; Weyhenmeyer, Jonathan; Hernandez, Manuel E.; Poizner, Howard; Sejnowski, Terrence J.

    2013-01-01

    Time series analysis with delay differential equations (DDEs) reveals non-linear properties of the underlying dynamical system and can serve as a non-linear time-domain classification tool. Here global DDE models were used to analyze short segments of simulated time series from a known dynamical system, the Rössler system, in high noise regimes. In a companion paper, we apply the DDE model developed here to classify short segments of encephalographic (EEG) data recorded from patients with Parkinson’s disease and healthy subjects. Nine simulated subjects in each of two distinct classes were generated by varying the bifurcation parameter b and keeping the other two parameters (a and c) of the Rössler system fixed. All choices of b were in the chaotic parameter range. We diluted the simulated data using white noise ranging from 10 to −30 dB signal-to-noise ratios (SNR). Structure selection was supervised by selecting the number of terms, delays, and order of non-linearity of the model DDE model that best linearly separated the two classes of data. The distances d from the linear dividing hyperplane was then used to assess the classification performance by computing the area A′ under the ROC curve. The selected model was tested on untrained data using repeated random sub-sampling validation. DDEs were able to accurately distinguish the two dynamical conditions, and moreover, to quantify the changes in the dynamics. There was a significant correlation between the dynamical bifurcation parameter b of the simulated data and the classification parameter d from our analysis. This correlation still held for new simulated subjects with new dynamical parameters selected from each of the two dynamical regimes. Furthermore, the correlation was robust to added noise, being significant even when the noise was greater than the signal. We conclude that DDE models may be used as a generalizable and reliable classification tool for even small segments of noisy data. PMID

  10. Non-linear Dynamical Classification of Short Time Series of the Rössler System in High Noise Regimes

    Directory of Open Access Journals (Sweden)

    Claudia eLainscsek

    2013-11-01

    Full Text Available Time series analysis with delay differential equations (DDEs reveals nonlinear properties of the underlying dynamical system and can serve as a non-linear time-domain classification tool. Here global DDE models were used to analyze short segments of simulated time series from a known dynamical system, the Rössler system, in high noise regimes. In a companion paper, we apply the DDE model developed here to classify short segments of encephalographic (EEG data recorded from patients with Parkinson's disease and healthy subjects. Nine simulated subjects in each of two distinct classes were generated by varying the bifurcation parameter b and keeping the other two parameters (a and c of the Rössler system fixed. All choices of b were in the chaotic parameter range. We diluted the simulated data using white noise ranging from 10dB to -30dB signal-to-noise ratios (SNR. Structure selection was supervised by selecting the number of terms, delays, and order of nonlinearity of the model DDE model that best linearly separated the two classes of data. The distances d from the linear dividing hyperplane was then used to assess the classification performance by computing the area A' under the ROC curve. The selected model was tested on untrained data using repeated random sub-sampling validation. DDEs were able to accurately distinguish the two dynamical conditions, and moreover, to quantify the changes in the dynamics. There was a significant correlation between the dynamical bifurcation parameter b of the simulated data and the classification parameter d from our analysis. This correlation still held for new simulated subjects with new dynamical parameters selected from each of the two dynamical regimes. Furthermore, the correlation was robust to added noise, being significant even when the noise was greater than the signal. We conclude that DDE models may be used as a generalizable and reliable classification tool for even small segments of noisy data.

  11. Investigations for low noise cooling by means of a pulse tube cooler for highly sensitive SQUID magnetometers from high temperature superconductors

    CERN Document Server

    Lienerth, C

    2000-01-01

    110fT/[Root]Hz at 10 Hz. For the discret peaks at the working frequency the vibration compensation is capable of reducing the cooler-generated peaks in the field noise spectrum by a factor of the order of 4. This noise level is low enough for applications such as nondestructive evaluation of materials. For identifying the origin of the remaining disturbances, one has to consider in addition to the residual vibrations also temperature oscillations and oscillating fields from eddy current at the SQUID location. The commercial acceptance of superconducting applications is closely associated with the availability of appropriate cryocoolers that enable continuous operation without the need to re-fill liquid cryogens. For cooling of highly-sensitive HT-SQUID sensors the cryocooler has to meet rather severe demands concerning interference from the cooler itself. In particular, cooler-generated noise from electromagnetic interference (EMI), mechanical vibrations and temperature fluctuations should be below the intrin...

  12. A new method of reconstructing very-high-energy gamma-ray spectra: the Template Background Spectrum

    CERN Document Server

    Fernandes, M V; Kosack, K; Raue, M; Rowell, G

    2014-01-01

    Very-high-energy (VHE, E>0.1 TeV) gamma-ray emission regions with angular extents comparable to the field-of-view of current imaging air-Cherenkov telescopes (IACT) require additional observations of source-free regions to estimate the background contribution to the energy spectrum. This reduces the effective observation time and deteriorates the sensitivity. A new method of reconstructing spectra from IACT data without the need of additional observations of source-free regions is developed. Its application is not restricted to any specific IACT or data format. On the basis of the template background method, which defines the background in air-shower parameter space, a new spectral reconstruction method from IACT data is developed and studied, the Template Background Spectrum (TBS); TBS is tested on published H.E.S.S. data and H.E.S.S. results. Good agreement is found between VHE gamma-ray spectra reported by the H.E.S.S. collaboration and those re-analysed with TBS. This includes analyses of point-like sourc...

  13. A high-efficiency, low-noise power solution for a dual-channel GNSS RF receiver

    Science.gov (United States)

    Jian, Shi; Taishan, Mo; Jianlian, Le; Yebing, Gan; Chengyan, Ma; Tianchun, Ye

    2012-08-01

    A high-efficiency low-noise power solution for a dual-channel GNSS RF receiver is presented. The power solution involves a DC—DC buck converter and a followed low-dropout regulator (LDO). The pulse-width-modulation (PWM) control method is adopted for better noise performance. An improved low-power high-frequency PWM control circuit is proposed, which halves the average quiescent current of the buck converter to 80 μA by periodically shutting down the OTA. The size of the output stage has also been optimized to achieve high efficiency under a light load condition. In addition, a novel soft-start circuit based on a current limiter has been implemented to avoid inrush current. Fabricated with commercial 180-nm CMOS technology, the DC—DC converter achieves a peak efficiency of 93.1% under a 2 MHz working frequency. The whole receiver consumes only 20.2 mA from a 3.3 V power supply and has a noise figure of 2.5 dB.

  14. 强噪声暴露后不同持续时间中等水平噪声暴露对豚鼠听力的保护作用研究%The protective effect of moderate noisy backgrounds for certain period on hearing after exposure to a traumatic noise in guinea pig

    Institute of Scientific and Technical Information of China (English)

    王晓花; 章建程; 王艳军; 周宏元; 徐灵活; 胡家庆

    2013-01-01

    Objective To investigate the protective effect of moderate noisy backgrounds on guinea pig's hearing after an exposure to a traumatic noise. Methods Thirty guinea pigs were randomly divided into five groups (6 each). Animals in group A, B, C and D were subjected to noise of 84 decibels sound pressure level (dB SPL) for 4, 8, 24 and 0 hour respectively after a traumatic exposure of 110 dB SPL, and those in group E were kept in quiet environment. Distortion product oto-acoustic emission (DPOAE) amplitudes were determined on 1 day prior, and 1 and 7 days after noise exposure. Blood plasma was obtained to determine the contents of malondialdehyde (MDA) and the activities of hemocuprein (SOD) and nitricoxide synthase (NOS) at the end of the experiment. Results Noise-induced hearing loss was caused in group D after a traumatic exposure. At the 1st and 7th day after exposure, DPOAE amplitudes were higher in group A and B than in group D, especially at high frequencies, while no significant difference was observed between group C and D. At the 7th day after exposure, the activity of SOD lowered, while the content of MDA increased in group A and B as compared with group E (P<0.05). The content of MDA in group A increased as compared with group D (P<0.05). Conclusion After the traumatic noise-exposure, the recovery of noise-induced hearing loss, especially the high-frequency hearing loss could be motivated when exposed to noise at 84 dB SPL for 4 or 8 hours.%目的 探讨强噪声暴露后中等水平噪声环境对豚鼠听力的保护作用.方法 30只雄性健康白化种红目豚鼠随机分为5组,每组6只.A、B、C和D组分别于110dB SPL白噪声暴露4h后继续84dB SPL噪声暴露4、8、24、0h;E组为空白对照,不施加噪声暴露.噪声暴露前1d、暴露后1d和7d进行3次畸变产物耳声发射(DPOAE)测定.测试完毕后,取血浆测试超氧化物歧化酶(SOD)、丙二醛(MDA)含量及一氧化氮合酶(NOS)活力.结果 强噪声暴露后,D组

  15. Multiple testing issues in discriminating compound-related peaks and chromatograms from high frequency noise, spikes and solvent-based nois in LC-MS data sets

    NARCIS (Netherlands)

    Nyangoma, S.O.; Van Kampen, A.A.; Reijmers, T.H.; Govorukhina, N.I; van der Zee, A.G.; Billingham, I.J; Bischoff, Rainer; Jansen, R.C.

    2007-01-01

    Multiple testing issues in discriminating compound-related peaks and chromatograms from high frequency noise, spikes and solvent-based noise in LC-MS data sets.Nyangoma SO, van Kampen AA, Reijmers TH, Govorukhina NI, van der Zee AG, Billingham LJ, Bischoff R, Jansen RC. University of Birmingham. Liq

  16. A Spectral Feature of High-Redshift Gamma-Ray Bursts Probing the Earliest Starlight Background Radiation

    CERN Document Server

    Dai, Z G

    2002-01-01

    Gamma-ray bursts (GRBs) and their afterglows at high redshifts have been widely believed to be detectable. Here we analyze a new feature of the MeV spectra of high-redshift GRBs, which is unlikely to appear in low-redshift GRBs. We generally discuss high-energy emission above a few decades of GeV due to synchrotron self-Compton scattering in the internal shock model. Our discussion seems to be supported by the high-energy spectra of several low-redshift GRBs. However, if GRBs originate at high redshifts (e.g., $z\\ge 6$), such photons cannot be detected because they may collide with cosmic optical and ultraviolet background photons, leading to electron/positron pair production. We show that inverse-Compton scattering of the resulting electron/positron pairs off cosmic microwave background photons will produce an additional multi-MeV component, resulting thus in a spectral "bump". We also derive the scattered photon spectrum of such a bump, $\

  17. Users' manual for the Langley high speed propeller noise prediction program (DFP-ATP)

    Science.gov (United States)

    Dunn, M. H.; Tarkenton, G. M.

    1989-01-01

    The use of the Dunn-Farassat-Padula Advanced Technology Propeller (DFP-ATP) noise prediction program which computes the periodic acoustic pressure signature and spectrum generated by propellers moving with supersonic helical tip speeds is described. The program has the capacity of predicting noise produced by a single-rotation propeller (SRP) or a counter-rotation propeller (CRP) system with steady or unsteady blade loading. The computational method is based on two theoretical formulations developed by Farassat. One formulation is appropriate for subsonic sources, and the other for transonic or supersonic sources. Detailed descriptions of user input, program output, and two test cases are presented, as well as brief discussions of the theoretical formulations and computational algorithms employed.

  18. FROST: a low-noise high-rate photon counting ASIC for X-ray applications

    Energy Technology Data Exchange (ETDEWEB)

    Prest, M. E-mail: prest@ts.infn.it; Vallazza, E.; Chiavacci, M.; Mariani, R.; Motto, S.; Neri, M.; Scantamburlo, N.; Arfelli, F.; Conighi, A.; Longo, R.; Olivo, A.; Pani, S.; Poropat, P.; Rashevsky, A.; Rigon, L.; Tromba, G.; Castelli, E

    2001-04-01

    FRONTier RADiography is an R and D project to assess the feasibility of digital mammography with Synchrotron Radiation at the ELETTRA Light Source in Trieste. In order to reach an acceptable time duration of the exam, a fast- and low-noise photon counting ASIC has been developed in collaboration with Aurelia Microelettronica, called Frontrad ReadOut SysTem. It is a multichannel counting system, each channel being made of a low-noise charge-sensitive preamplifier optimized for X-ray energy range (10-100 keV), a CR-RC{sup 2} shaper, a discriminator and a 16-bit counter. In order to set the discriminator threshold, a set of a global 6-bit DAC and a local (per channel) 3-bit DAC has been implemented within the ASIC. We report on the measurements done with the 8-channel prototype chip and the comparison with the simulation results.

  19. Noise properties of high-quality step-edge YBCO Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Foley, C.P.; Lam, S.; Sloggett, J.; Savvides, N; Katsaros, A. [CSIRO, Lindfield, NSW (Australia). Division of Applied Physics; Hao, L.; Macfarlane, J.C.; Pegrum, C.M. [University of Strathclyde, Glasgow (United Kingdom). Department of Physics and Applied Physics; Kuznik, J. [Czech Academy of Science, Prague (Czech Republic).

    1996-12-31

    Full text: We report the results of noise and other measurements on YBCO step-edge Josephson junctions whose morphology closely approaches the ideal of a homogeneous tilt angle grain boundary. The junctions exhibit near-perfect resistively-shunted-junction (RSJ) current voltage characteristics and magnetic field dependence. Excess noise in the junctions was comparable to the best bicrystal types previously measured, the normalised amplitude of the critical current fluctuations, S{sub i}{sup 1/2}, being less than 1x10{sub -4} Hz{sub -}1{sub /2} at 1 Hz and 77 K. S{sub i}{sup 1/2} was found to be independent of temperature and also independent of magnetic field provided the zero-field critical current was used for normalisation

  20. Improved background rejection in neutrinoless double beta decay experiments using a magnetic field in a high pressure xenon TPC

    CERN Document Server

    Renner, J; Hernando, J A; Imzaylov, A; Monrabal, F; Muñoz, J; Nygren, D; Gomez-Cadenas, J J

    2015-01-01

    We demonstrate that the application of an external magnetic field could lead to an improved background rejection in neutrinoless double-beta (0nbb) decay experiments using a high pressure xenon (HPXe) TPC. HPXe chambers are capable of imaging electron tracks, a feature that enhances the separation between signal events (the two electrons emitted in the 0nbb decay of 136Xe) and background events, arising chiefly from single electrons of kinetic energy compatible with the end-point of the 0nbb decay (Qbb ). Applying an external magnetic field of sufficiently high intensity (in the range of 0.5-1 Tesla for operating pressures in the range of 5-15 atmospheres) causes the electrons to produce helical tracks. Assuming the tracks can be properly reconstructed, the sign (direction) of curvature can be determined at several points along these tracks, and such information can be used to separate signal (0nbb) events containing two electrons producing a track with two different directions of curvature from background (s...